The motto of the congress truly reflects the significant role of foundry production and development machine-building complex Russia. The share of cast parts on average accounts for 50-70% of the mass (in machine tool industry up to 90%) and 20-22% of the cost of machines.

As a rule, cast parts bear high loads in machines and mechanisms and determine their operational reliability, accuracy and durability. Therefore, increased demands are currently placed on the quality of castings.

The concept of “High-quality casting” combines a set of requirements for cast parts used in machines and mechanisms of various industries. The main requirements are: strength and performance characteristics, geometric and dimensional accuracy, surface cleanliness, marketable condition, minimum allowances for machining.

The process of obtaining a high-quality casting consists of two main technological complexes: obtaining a high-quality melt and preparing a casting mold. However, even with high-quality implementation These technological processes can result in defective castings when pouring the alloy into a mold and cooling the casting in contact with the mold material. Therefore, the technological cycle for producing a cast part is long and responsible.

The first technological complex consists of the following technological methods: preparation of charge materials and melting them in a melting unit, thermal and temporary processing of the melt in a furnace, out-of-furnace processing of the melt (modification, refining) and pouring it into a casting mold.

The second complex: preparation of molding and core mixtures, production of molds and cores, assembly of molds and supplying them for pouring (in the manufacture of molds from sand-clay and cold-hardening mixtures) or production of metal molds for chill casting, injection molding, centrifugal casting etc. After pouring, hardening and cooling in the mold, the processes of knocking out, cleaning, heat treatment, and priming of the castings are carried out.

Despite the use of a large number of technological methods and a significant list of materials, foundry and auxiliary equipment for the production of high-quality castings, foundry production in Russia occupies a leading position among other procurement industries of the machine-building complex such as welding and forge. Only foundry production makes it possible to produce shaped blanks with complex configurations and geometries with internal cavities made of ferrous and non-ferrous alloys, weighing from a few grams to 200 tons.

Foundry production is the most knowledge-intensive, energy-intensive and material-intensive production. During development theoretical foundations technological processes, the basic sciences are applied: physics, chemistry, physical chemistry, hydraulics, mathematics, materials science, thermodynamics and other applied sciences.

To produce 1 ton of suitable castings, 1.2-1.7 tons of metal charge materials, ferroalloys, modifiers are required, processing and preparation of 3-5 tons of molding sands (for casting in sand-clay molds), 3-4 kg of binding materials (for casting into molds from CTS) and paints. Electricity consumption when melting ferrous and non-ferrous alloys in electric furnaces ranges from 500 to 700 kW/hour. In the cost of casting, energy costs and fuel are 50-60%, the cost of materials is 30-35%.

Advances in science, the development of new technological processes, materials and equipment have made it possible over the past 10 years to increase the mechanical and operational characteristics of alloys by 20%, increase dimensional and geometric accuracy, reduce machining allowances, and improve marketability.

Improving the quality of casting is inextricably linked with increasing productivity, automation and mechanization of technological processes, economic and environmental indicators. Therefore, during the construction of new and reconstruction of old foundries and factories, the choice of technological processes and equipment is made based on the type of alloy, the mass and range of castings, the volume of production of castings, technical requirements to castings of technical, economic and environmental indicators.

To develop perspectives and strategy further development foundry production requires an assessment of its condition in Russia as a whole and separately in various industries, determining the prospects for the development of priority industries and, on their basis, determining the prospects for the development of ferrous and non-ferrous alloys, technological processes and equipment.

Let's consider current state foundry production in Russia.

In 2015, 104.1 million tons of castings from ferrous and non-ferrous alloys were produced worldwide. The production volumes of cast billets from ferrous and non-ferrous alloys in countries around the world are presented in Fig. 1.

Rice. 1

According to experimental estimates, there are currently about 1,100 operating foundries in Russia, which produced 3.8 million tons of castings in 2016, and about 90 enterprises that produce equipment and materials for foundry production.

The distribution of foundries and factories in Russia by capacity is presented in Fig. 2.

Rice. 2 Distribution of foundries and plants by capacity, 1000 t/year and %

Currently in Russia the main number of foundries (70%) with a capacity of up to 5 thousand tons per year.

The dynamics of production of castings from ferrous and non-ferrous alloys in the period from 1985 to 2016 are presented in Table 1.

Table 1

Dynamics of casting production and development prospects until 2020

Years	1985	1990	2000	2005	2010	2014	2015	2016	2020
Production of castings in million tons, incl. from:	18,5	13,4	4,85	7,6	3,9	4,1	4,0	3,8	5,0
Cast iron	12,9	9,3	3,5	5,2	2,9	2,9	2,6	2,2	2,6
Become	3,1	3,24	0,96	1,3	0,6	0,7	0,9	1,0	1,4
Non-ferrous alloys	2,5	0,86	0,39	1,1	0,4	0,5	0,5	0,6	1,0

In Fig. Figure 3 shows the dynamics of development of casting production over the past 12 years and prospects until 2020.

The main reasons for the sharp decline in casting production volumes in the period from 1985 to 2010 were:

1. Privatization. Many factories (about 30%) were abandoned, equipment and communications were cut up and scrapped, including the “Tsentrolit” factories, which produced about 1.5 million tons of castings.

2. General economic and technical crisis. Lack of laws, a chain of mutual non-payments, overstocking of finished products at enterprises, lack of working capital, wage arrears.

3. High lending rates, high taxes and customs duties.

4. High prices for energy, materials, low wage and etc.

Therefore, from 1985 to 2010, the volume of production of cast billets decreased by 4.7 times.

In the second period from 2005 to 2016, these reasons that were destroying the foundry industry were supplemented by the fashionable thesis “Everything that can be bought, does not need to be produced.”

As a result, currently the bulk of equipment not only in foundry production, but also in metallurgy, utilities, agriculture and other industries is purchased abroad. In this formulation of the question, castings are not in demand. The process of bankruptcy and liquidation of foundries and factories continues. Thus, from 1985 to the present, the number of foundries and factories has decreased from 2500 to 1200, i.e. by 52%, average load existing foundries account for 42%.

By 2020, we can expect an increase in casting production due to the development oil and gas industry, railway, defense, aerospace and other industries. It is mainly predicted that there will be an increase in the production of castings from steel, high-strength cast iron, aluminum, titanium and magnesium alloys, and a decrease in imports of foundry equipment due to import substitution.

Over the past 5 years, production volumes of steel castings increased by 14.2%, castings from non-ferrous alloys - by 15%, and cast iron decreased by 24%. In the long term from 2016 to 2020. assumed (according to expert assessment) growth in the production of castings to 5 million tons due to import substitution of the production of castings from non-ferrous alloys (aluminium, magnesium, titanium, special), automotive components, steel castings for valve making, oil and gas industry, railway transport, increasing production volumes of domestic equipment and related materials for various industries.

The dynamics of production volumes in Russia of castings, equipment and materials are shown in Table 2.

table 2

Dynamics of production volumes in Russia of castings, equipment and materials

Years	2012	2016	2020
Production of castings, %	82	90	96
Equipment production, %	30	35	45
Production of materials,%	70	80	85

Domestic foundry equipment is mainly produced at the following enterprises: Siblitmash JSC, Dalenergomash JSC - Amurlitmash, Litmashpribor LLC, Unirep-service LLC, Tebova-Nur LLC, AKS Plant LLC, Toledo LLC. Melting equipment is produced by: LLC SKB "Sibelektorotherm", LLC "NPF Komter", LLC "Reltek", CJSC "Nakal-Industrial Furnaces", Novozybkovsky Electrical Equipment Plant, Saratov Plant "Elektorterm-93", LLC "Electrotechnology", Yekaterinburg and LLC "Kurai" Ufa.

However, they do not fully satisfy the needs of foundries and factories. Therefore, about 65% of foundry equipment is purchased abroad, in countries such as Germany, Italy, China, Japan, Turkey, the Czech Republic, etc.

Currently, the following equipment is not produced in Russia:

• automatic and mechanized high-performance lines for the production of flask and non-flask molds from raw sand-clay and cold-hardening mixtures;
• machines for making molds from sand-clay mixtures with flask sizes from 400*500 mm to 1200*1500 mm.
• machine for making casting cores using hot and cold tooling;
• equipment for painting foundry molds;
• batch and continuous mixers for the production of chemical mixtures with a capacity of more than 10 t/hour.
• chilling machines and low pressure casting machines;
• centrifugal casting machines;
• medium frequency induction furnaces with a capacity of more than 6 tons for smelting cast iron and steel:
• equipment for the regeneration of chemical mixtures;
• Equipment for heat treatment castings

Therefore, during the planned period it will be necessary to purchase foundry equipment and related technologies.

It should be noted that individual species equipment produced in Russia is inferior to foreign equipment in quality, and in some cases, in cost.

Resolution No. 9 of January 14, 2017 prohibits the purchase of equipment that is not produced in Russia. However, prohibition alone cannot solve the issues of producing high-quality equipment. It is necessary to determine a list of the main factories - manufacturers of foundry equipment and provide them with financial assistance to modernize production.

In 2016, imports of equipment and spare parts from all countries of the world amounted to about 500 million US dollars. Compared to 2015, equipment imports decreased by 9%.

According to expert assessment, existing factories today do not have enough capacity to produce the equipment required by the foundry industry. It is necessary to build new production facilities equipped with modern technological equipment or to retrain factories in other industries, in particular factories in the machine tool industry.

Cast parts made of ferrous and non-ferrous alloys are widely used in various industries. Each industry imposes corresponding specific requirements for castings in terms of nomenclature, mechanical and operational properties, type of alloy, weight of castings, and, accordingly, by type of technological processes and equipment.

The production of castings by industry is shown in Fig. 3.

The production of castings from ferrous and non-ferrous alloys is shown in Fig. 4.

Distribution of casting production volumes by technological production processes in Fig. 5.

Rice. 3.

Rice. 4. Production of castings from ferrous and non-ferrous alloys by industry, %

Rice. 5.

Over the past 5 years, more than 160 foundries have been completely or partially reconstructed. Promising technological processes are being widely mastered: melting casting alloys in induction and electric arc furnaces, increasing the share of production of castings from high-strength cast iron, magnesium and aluminum and titanium alloys, manufacturing molds and cores of their cold-hardening mixtures, modeling foundry processes using numerical, including 3D- technologies.

IN last years The production volumes of castings from aluminum and magnesium alloys have increased, which in some cases replace castings from cast iron and steel. Applying modern methods By refining, modifying, microalloying and degassing, high strength characteristics of alloys up to 450–500 MPa can be obtained.

The production volumes of cast billets from non-ferrous alloys (according to experimental estimates) are given in Table. 3

Alloy type	Production of castings, thousand tons/%
Total non-ferrous alloys	600/100
From aluminum alloys, including ingots	440/73,3
Made from magnesium alloys	30/5,0
Their copper alloys	80/13,3
Made from titanium alloys	20/3,4
Nickel alloys	10/1,6
And other alloys	20/3,4

For smelting ferrous alloys promising technologies are melting in electric arc and induction furnaces, providing a stably specified chemical composition and temperature for out-of-furnace processing using refining and modified methods.

From 2010 to 2016 The volume of cast iron smelting in induction furnaces and the duplex process increased by 30%. It should be taken into account that the increase in production volumes of electric smelting of cast iron is carried out not only by replacing cupola furnaces with induction furnaces, but also by closing foundries with cupola smelting of cast iron.

The transition to electric melting of cast iron made it possible to increase the production of castings from high-strength cast iron by 12.5%.

Accordingly, the average composition of charge materials during the smelting of cast iron in various smelting units also changed. The amount of steel and cast iron scrap in the charge increased by 15% and the amount of pig foundry and pig iron decreased by 28%.

Methods for producing casting molds and cores play an important role in obtaining high-quality castings. Dynamic methods for compacting casting molds from cold-hardening mixtures are promising. Currently, the production of molds from ASG is 60%, from CTS - 40%. Over the past 5 years, the production of molds for their chemical engineering has increased by 11%.

Thus, the most promising directions development of foundry production are:

Melting of ferrous alloys in medium frequency induction furnaces and arc furnaces of alternating and direct current;

• Creation and production modern equipment for the manufacture of casting molds and cores:
• Development of production of castings from high-strength cast iron and castings from aluminum, magnesium, titanium, and special alloys;
• Construction of new and reconstruction of old foundries for the production of foundry equipment, consolidation of foundries and mergers into corporations.

Modernization of foundry production is closely related to personnel training. Without training specialists of a new generation, it is impossible to create and master new technologies aimed at improving product quality and increasing labor productivity.

The experience of recent years shows that the training of personnel (engineers, technicians, workers) must begin with the school family. The level of training in schools is significantly lower than the level of requirements that are imposed on school graduates upon admission to higher educational institutions.

Interest on the part of young people in studying at a university for a foundry specialty has noticeably decreased, and the prestige of technical work is sharply decreasing. It is necessary to return to the methodology of training engineers at universities, distributing specialists among the country's enterprises with the provision of social benefits.

All scientific activity is concentrated in the foundry departments of universities, which are not provided with modern research equipment and teaching aids.

In recent years, the number of foundry departments has sharply decreased; the process of merging foundry departments with the departments of welding, metallurgy, and materials science is underway. The connection between science and production is broken; there is no close connection between universities and enterprises regarding the preparation and use of bachelors. As a result, only 30% of foundry department graduates work in their specialty, and foundry enterprises do not have highly qualified specialists.

Currently, about 350 thousand people work in the foundry industry, including workers - 92%, economists and managers - 3%, engineers - 4.8%, scientific workers— 0.2% (Fig. 6.)

Rice. 6.

In this regard, the training of teaching staff cannot be excluded. Today, the training of specialists often lags behind the development of production.

The modernization and reconstruction of foundries continues slowly on the basis of new environmentally friendly technological processes and materials, progressive equipment, ensuring the production of high-quality castings that meet international standards.

However, some examples of partial modernization of foundry production do not meet international standards, the pace of improvement in the quality of castings and the increase in labor productivity. Today it is necessary to build flexible production facilities that ensure the continuity of the equipment technological chain and the possibility of its changeover when producing a wide range of castings.

It is necessary to develop a strategy and tactics for the development of foundry production in Russia for the next 10-15 years. Considering the intersectoral nature of foundry production, it should be developed by highly qualified specialists with rich practical experience with the active support of the Government of the Russian Federation.

Each branch of the machine-building complex has its own characteristics regarding the use of cast blanks from ferrous and non-ferrous alloys, the mechanical and operational properties of castings, the use of cast blanks from ferrous and ferrous and non-ferrous alloys, the mechanical and operational properties of castings, the use of technological processes and equipment for the production of castings, weight and nomenclature of cast parts, type of production (small-scale, serial, mass), etc.

Therefore, at the first stage, it is necessary to create working groups and analyze the existing production of cast billets by industry and determine the prospects for their development until 2020 and 2030.

Based on these data, it will be possible to determine priority industries, production volumes of castings from ferrous and non-ferrous alloys, and the need for equipment and materials.

In parallel, it is necessary to develop a strategy for the development of foundry engineering and personnel training. It is necessary to determine the production and technological capabilities of the production of foundry equipment at existing plants, to determine the list of equipment that is subject to import substitution, and which must be purchased abroad within the specified time frame of the strategy.

Therefore, developing a strategy for the development of foundry production in Russia is a complex, intersectoral and complex task that requires certain time and financing. In the absence of clear data on the needs of castings: “how many”, “what” and “to whom”, a foundry development strategy cannot be developed and successfully implemented.

To realize the prospects for the development of foundry production within the framework of the strategy, it is necessary:

1. Create Federal science Center for foundry production to coordinate scientific activities, communicate academic science with Ministries, Universities and factories.
2. Create a foundry production department within the structure of the Ministry of Industry and Trade of the Russian Federation and equip it with specialists with the responsibility of coordinating the technical and technological activities of foundry enterprises in various industries, developing new technological processes, equipment and materials, improving the qualifications of engineers, middle managers and workers.
3. Create research and production centers at the foundry departments of the country's universities and equip them with modern technological equipment, instruments and specialists.
4. Construction of new or modernization of old machine-building plants, including machine tools for the manufacture of foundry equipment. provide them with the necessary funding.
5. Renew the State annual reporting of foundry enterprises for the production and purchase of products (equipment, materials, castings, (for alloys).
6. Recommend that the Ministry of Education and Science assign the status of acutely shortage specialties in the “Foundry” profile and resume engineering training in universities.
7. Pay attention to activities public organizations and give them appropriate powers and financial support, taking into account the experience of BRICS foundry associations with the Government.
8. Establish a professional holiday “Foundryman’s Day” on the first Sunday of June.

We hope that through the joint efforts of scientists, researchers, enterprise managers, foundry specialists, public organizations with the active support of the Government of the Russian Federation, it will be possible to significantly increase the competitiveness of Russian foundry production at the global level.

I. A. Dibrov, professor, Doctor of Technical Sciences, President of the Russian Association of Foundry Workers, Honored Metallurgist of the Russian Federation, Chief Editor magazine "Foundryman of Russia"

It's called casting technological process obtaining parts from liquid metal in foundry molds. A casting mold is an element that has an internal cavity that forms a part when filled with straightened metal. After the metal has cooled and solidified, the mold is destroyed or opened and a part with a given configuration and required dimensions is removed (Fig. 13.1). Products obtained by this method are called castings. The production of products by casting is called foundry.

Foundry production is one of the most important industries in mechanical engineering. Cast billets are consumed by most sectors of the national economy. The weight of cast parts in machines is:

Rice. 13.1. The design of the mold and casting is on average 40-80%, and the cost and labor intensity of their production is approximately 25% of the total costs of the product.

The method of producing parts by casting is cheaper compared to forging and stamping, since cast blanks are closest in size and configuration to finished parts, and the volume of their machining is less than on blanks produced by other methods. Casting produces castings of very complex configurations, especially hollow ones, which cannot be made by forging, stamping or other mechanical processing from rolled or pressed material, for example, cylinder blocks, machine beds, turbine blades, gear wheels, gas and water fittings and much more. The weight of cast parts is not limited - from several grams to tens of tons. Only casting can produce products from various alloys, any size, complexity and weight, for relatively a short time, with fairly high mechanical and operational properties.

Foundries in which foundry production is carried out are classified depending on the alloy used, casting production technology, weight of castings, etc. (Fig. 13.2).

Based on the type of alloy (metal) used, workshops are distinguished: iron foundries, steel castings and non-ferrous castings.

In iron foundries, castings are made from gray, high-strength, malleable and other types of cast iron.

In steel casting shops, castings are made from cast steels: carbon, structural, heat-resistant, special steels, etc.

Non-ferrous casting shops use metals and alloys such as aluminum, copper, magnesium, zinc, titanium, bronze, brass, etc.

Based on the weight and dimensions of the casting, foundry shops can be classified as light, medium, large, heavy and especially heavy weight, or according to another classification - small, medium or large-sized casting shops.

By type of casting, foundry production is classified into sand-clay casting and special casting.

Under special types Castings include chill casting (permanent metal molds), centrifugal casting, lost-wax casting (precision casting), burn-out casting, high- or low-pressure casting, cork casting, etc.

The most common method in foundry production is casting in sand-clay molds. Foundry molds are made from molding sands. The main components of molding sands are sand and clay, which is why this type is still

Rice. 13.2. The main groupings of casting foundries are called “earth casting”. Earth casting accounts for over 75% of the total production of castings. They are one-time molds because removing the casting requires their destruction. To obtain each subsequent part, it is necessary to make a new mold. The process of making a mold is called molding.

Molding sands are intended for the production of casting molds, and core sands are used for making cores. Molding and core mixtures must be pliable to produce a distinct imprint; fireproof - to withstand high temperatures of the poured metal; durable - to withstand the pressure of the metal being poured; gas-permeable, i.e. capable of allowing emitted gases to pass through, as well as non-stick, capable of not sintering with the straightened metal.

The rods are in even more difficult conditions. Therefore, core mixtures have higher properties than molding mixtures.

When molding, special devices are used, the set of which is called a model kit and flasks.

A model kit is made for each part separately, based on its configuration and dimensions. It consists of a model, gating system elements and a sub-model plate. If there are cavities or holes in the design of the part, then the kit also includes core boxes.

The model is designed to form the outer contour of a part in a mold. It is manufactured with casting slopes, allowances for subsequent processing and metal shrinkage.

A gating system is a set of channels that supply molten metal into the mold cavity.

A model plate is a device designed for installing a model and a gating system.

The core box is designed for the manufacture of cores that form the internal contour of the part cavity.

The flasks are rigid frames in which the casting mold is held during its transportation and pouring with metal.

As for casting alloys, only those metals and alloys that have good casting properties are used in foundry production: high fluidity, low shrinkage and low tendency to segregation.

Fluidity is the ability of a metal to fill mold cavities.

Shrinkage is the property of metals to decrease in size as they cool.

Liquation is the heterogeneity in the chemical composition of different parts of the casting.

Foundry production is one of the most organizationally and technically complex machine-building processes. The organization of foundries, which has a large amount of initial data, is a labor-intensive and complex process. However, standard designs of the main sections of foundries with a set of equipment, standard technology and production organization have been developed.

The basis for the design of the workshop and all its departments is the workshop program.

Methods for making castings, their features and scope of application are shown in table. 13.1.

Foundries are usually located in separate buildings.

Frame-type buildings are designed for foundries. The supporting frame consists of columns mounted on foundations and connected by beams and trusses. Column trusses and the trusses resting on them form transverse frames, which are connected in the longitudinal direction by foundation strapping beams, crane beams. Such a building provides effective mechanical ventilation, aeration and lighting.

The foundation, columns, walls and ceilings form the load-bearing frame of the building, which takes on all the loads. The roof covering depends on the type of building covering, the climatic conditions of the area and the internal conditions of the room. The most commonly used are rolled multilayer roofs made of waterproof materials, which are laid over a layer of insulation using bitumen mastic. Since buildings have many spans, it is necessary to arrange internal water drainage through funnels in the roof and risers into the storm drain. The roof is built according to the lantern type. The type of lanterns for industrial buildings is assigned in accordance with the technological, sanitary and hygienic requirements and climatic conditions of the construction area. Lanterns installed on the roof of industrial buildings are divided into light, aeration and light-aeration, and according to their location relative to the spans - into strip and spot. For the central climate zone in rooms with large heat releases, light-aeration double-sided lanterns with vertical glazing are used.

At the stage of developing a feasibility study and when drawing up assignments for designing a foundry, it is necessary to take into account:

• 1) availability of access roads, including railways;
• 2) the presence of significant energy resources;
• 3) predominant wind direction;
• 4) the presence of treatment facilities and storage areas for production waste;
• 5) remoteness from machining shops, etc.

For the right choice type of buildings, heating and ventilation systems, as well as load-bearing and enclosing structures, during technical surveys it is necessary to collect meteorological data: air temperature and humidity, wind speed, amount of rainfall, soil freezing depth, etc.

Table 13.1

Methods for making castings, their features and scope 1

Methods for making castings	Casting weight, t	Material
One-time forms
Hand molding: in soil with top			Beds, machine bodies, frames, cylinders, hammer heads, traverses
according to the template			Castings in the form of bodies of rotation (gears, rings, disks, pipes, pulleys, flywheels, boilers, cylinders)
in large flasks		Steel, grey, malleable and ductile iron, non-ferrous metals and alloys	Beds, headstocks, gearboxes, cylinder blocks
in removable flasks with cores made of a fast-setting mixture			GM K beds, automatic bolt-setting machines, scissors; allows you to reduce allowances by 25-30% and the labor intensity of machining by 20-25%
in soil with a top flask and a facing layer of a quick-hardening mixture			Chabots, frames, cylinders; allows you to reduce the labor intensity of workpiece manufacturing and machining by reducing allowances by 10-18%
in the rods			Castings with a complex ribbed surface (cylinder heads and blocks, guides)
open in the soil			Castings that do not require machining (plates, linings)

1 Handbook of mechanical engineering technologist. URL: http://stehmash.narod.ru/stmlstrl2tabl.htm

Methods for making castings	Casting weight, t	Material	Scope and feature of the method
in small and medium flasks			Handles, gears, washers, bushings, levers, couplings, covers
Machine molding: in large flasks			Headstocks, supports, bodies of small beds
in small and medium flasks			Gears, bearings, couplings, flywheels; allows you to produce castings of increased precision with low surface roughness
Shell casting: sand-resin			Critical shaped castings in large-scale and mass production
chemical hardening thin-walled (10-20 mm)		Steel, cast iron and non-ferrous alloys	Critical shaped small and medium castings
chemical hardening thick-walled (50-150 mm thick)			Large castings (stamping hammer beds, rolling mill chocks)
liquid glass shell		Carbon and corrosion-resistant steels, cobalt, chromium and aluminum alloys, brass	Precision castings with low surface roughness in mass production
lost wax casting		High alloy steels and alloys (except alkali metals, reacting with silica of the facing layer)	Turbine blades, valves, nozzles, gears, cutting tools, instrument parts. Ceramic rods allow the production of castings with a thickness of 0.3 mm and holes with a diameter of up to 2 mm
dissolvable casting		Titanium, heat-resistant steels	Turbine blades, instrument parts. Salt models reduce surface roughness
frozen casting			Thin-walled castings (minimum machine thickness 0.8 mm, hole diameter up to 1 mm)

Methods for making castings	Casting weight, t	Material	Scope and feature of the method
casting using gas-filled models		Any alloys	Small and medium castings (levers, bushings, cylinders, housings)
Multiple forms
Casting into molds: plaster			Large and medium castings in mass production
sand-cement
brick
fireclay-quartz
clayey
graphite
stone
metal-ceramic and ceramic
Chill casting: with horizontal, vertical and combined parting plane	7 (cast iron), 4 (steel), 0.5 (non-ferrous metals and alloys)	Steel, cast iron, non-ferrous metals and alloys	Shaped castings in large-scale and mass production (pistons, housings, discs, feed boxes, slides)
casting with lined mold		Austenitic and ferritic steel	Hydraulic turbine impeller blades, crankshafts, axle boxes, axle box covers and other large thick-walled castings
Injection molding: on machines with horizontal and vertical compression chambers		Magnesium, aluminum, zinc and lead-tin alloys, steel	Castings of complex configuration (tees, elbows, electric motor rings, instrument parts, engine block)
using vacuum		Copper alloys	Dense castings of simple shape
centrifugal casting on machines with a rotation axis: vertical			Castings of the type of bodies of rotation (rims, gears, tires, wheels, flanges, pulleys, flywheels), two-layer workpieces (cast iron-bronze, steel-cast iron) at /: d

Methods for making castings	Casting weight, t	Material	Scope and feature of the method
horizontal		Cast iron, steel, bronze, etc.	Pipes, sleeves, bushings, axles with /:d >1
inclined (tilt angle 3-6°)			Pipes, shafts, ingots
vertical, not coinciding with the geometric axis of the casting			Shaped castings that are not bodies of rotation (levers, forks, brake pads)
Stamping of liquid alloys:		Non-ferrous alloys	Ingots, shaped castings with deep cavities (turbine blades, fittings high pressure)
with crystallization under piston pressure		Cast iron and non-ferrous alloys	Massive and thick-walled castings without gas holes and porosity; it is possible to obtain compacted blanks from non-casting materials (pure aluminum)
squeeze casting	Panels up to 1000x 2500 mm thick	Magnesium and aluminum alloys	Large-sized castings, including ribbed ones
vacuum suction		Copper-based alloys	Small castings such as rotation bodies (bushings, sleeves)
sequentially directed crystallization		Non-ferrous alloys	Castings with wall thickness up to 3 mm and length up to 3000 mm
low pressure casting		Cast iron, aluminum alloys	Thin-walled castings with a wall thickness of 2 mm at a height of 500-600 mm (cylinder heads, pistons, liners)
continuous	Pipes with a diameter of 300-1000 mm

FOUNDRY, one of the technological processes for producing a product by filling a pre-prepared mold with molten metal, in which the metal hardens. The importance of foundry production in mechanical engineering is characterized by the fact that more than 75% by weight of all parts of machines and tools are cast. The production of parts by casting is not only a simple and therefore cheap method, but often with very complex designs and large dimensions of the parts - it is the only one. The foundry process can also produce products from metals that cannot be forged. In foundry production, machine parts are manufactured individually, in batches, and in some cases in mass quantities.

Foundry materials are: casting materials (cast iron, steel, copper and its alloys, aluminum and its alloys, etc.); molding materials (sand, clay, etc.); auxiliary materials: fuel, refractory materials, fluxes, etc. The main operations in foundry production are as follows: 1) preparation of molding earth, 2) making a mold (molding), 3) melting metal, 4) assembling and pouring the mold, 5) releasing the casting from molds (knocking out), 6) casting cleaning (cutting, cleaning and trimming), 7) heat treatment (annealing or complete heat treatment).

Making molds (molding). In foundry production, the following are used: temporary molds, mainly made of clay and sand, and permanent metal molds, Ch. arr. of steel. During solidification, the metal decreases in volume (shrinkage phenomenon), so the mold is made larger in size than the product by the amount of shrinkage. The phenomenon of shrinkage affects the strength of the casting, and sometimes even its integrity, when, for example, the molding mass (rods) surrounded by liquid metal is too strong and unyielding, and the casting metal contracts as it solidifies. Therefore, in temporary molds, the molding compound must be used. pliable; with permanent molds, it is necessary (depending on the rate of solidification of the metal) to throw out products from them in a timely manner, which is achieved by very precise (in time) action of the appropriate mechanisms.

Constant forms were developed by Ch. arr. for casting non-ferrous metals having a low melting point, and partly for cast iron; For steel, permanent forms are rarely used, since it is very difficult (even for cast iron) to select a metal that can withstand repeated heating and cooling. Casting into permanent molds with metal cones of aluminum alloys has become especially widespread. Permanent molds include the so-called long-life molds, proposed and patented by Holley Carburettor Co., Detroit. They are made from very durable fire-resistant material. The whole difficulty of making these forms lies in finding the appropriate material (kaolin, magnesia, bauxite) and connecting it well with the cast iron shell. The surface of the refractory layer can be adjusted until it wears out, after which the refractory layer is applied again. Cast iron and other metals (except steel) are cast into such molds. There is no bleaching of the cast iron and the casting is well processed.

Temporary molds are made using models or templates, which are an exact copy of the casting (increased by the amount of shrinkage), and flasks - rectangular or square (less often round) boxes without a bottom or lid. The flasks serve to give strength to the molding material and to use as little molding soil as possible during molding. Much less often, molding is done in the soil without flasks or with only one upper flask.

Schematically, the process of making molds is as follows. 1) Half of the model is placed on a sub-model plate (Fig. 1). 2) The lower half of the flask is placed on the slab and covered with a few mm of model soil (Fig. 2), lightly compacted around the model (in most cases by hand); after this, filling soil is poured into the flask (to the top or more), which is then compacted b. or m. greatly depending on the size and nature of the casting; the form is ventilated (pierced in several places with a hairpin).

3) The filled flask is turned over together with the model board (Fig. 3); the fake board is removed; The surface of the lower flask is sprinkled with separating sand. 4) On the lower half of the model, place the upper half of the model, covered with a layer of model sand, and the upper flask (Fig. 4), into which the sprue and butt models are placed (Fig. 5). 5) After compacting the filling soil, the flasks are separated and the models are removed from each half. 6) A rod is inserted into the lower mold freed from the model (Fig. 6), which is prepared separately. 7) The lower flask with the rod is covered with the upper flask (Fig. 7); the assembled flasks are loaded, i.e., a weight is placed on the upper flask to protect it from floating when the mold is filled with liquid metal.

Methods for filling flasks with molding material and compacting it are shown in Fig. 8.

Molding machines are divided into three main types: pressing, shaking and sand-throwing. Each molding machine is equipped with devices for releasing the model from the flask. The main methods for releasing the model from the flasks are shown in Fig. 9.

In accordance with the methods for releasing models from flasks, molding machines are also divided into subgroups: 1) machines with lifting flasks, 2) machines with a rotating plate and 3) machines with a broaching plate.

In fig. 10 shows an ordinary pressing (with manual pressing from below) molding machine; in fig. Figure 11 shows one of the newest types of shaking-press machines of the Nichols system, operating with compressed air.

The model plate of this machine is mounted on the model B holder; the flask (not shown in the diagram) is connected either to the model plate or to frame E, which serves as a support for the flask. Place valve handle N to the right. Shaking occurs; in this case, the air passes inside piston B under piston A, which carries the model plate. The lifting of the piston is controlled automatically by raising the windows F by the lower edge of the piston. Through these windows, air flows into piston B and into the atmosphere. During shaking, the traverses H with the pressing block stand above the flask.

Then the valve handle N is turned to the left. Then the air goes through another wire under piston B and lifts both pistons with the model plate, frames D and E and a shaken flask filled with sand and presses the latter against the press block, which is how compaction is achieved. Turn handle N again to the middle position, which opens the outlet of the press cylinder. Both pistons A and B, the model holder D with the model plate and the frame E supporting the flask fall down, and in addition to the press piston B, round rods G serve as guides. During movement, the rods G are stopped by pawls C at a known height so that frame E with the finished shape stops while B-A-D system with the model plate continue moving down; in this case, the model is pulled out of the mold. After pumping out the traverse with the press block, it is easy to remove the mold. To ensure precise vertical movement of the model D holder, there are four guide rods M in the shaking table. The rods G in the lower position are immersed in an oil bath, as well as the guides M, in order to ensure good lubrication and a smooth fall of the frame E, for which purpose the pawl C is turned to the right by moving the foot lever. On the frame E you can attach a broaching plate, on which the flask is already placed like this , so that with a tall model with steep walls, work using the pulling method. In both cases, a vibrator on frame D helps remove the model. In fig. Figure 12 shows one of the many designs of a sand blower - the latest molding machine, which simultaneously fills the flask with molding earth and compacts the latter by the action of centrifugal force.

The molding material is transferred via an elevator to a shaking chute, then to a belt, which transfers it to the sand thrower head; here the earth is picked up by a rapidly rotating bucket of the working head, which cuts off a portion of the earth from the total amount and, with enormous speed (12-18 m/sec), directs the earth into the flask, where it is compacted. The main advantage of the sand blower compared to other types of molding machines is that it is not associated with a certain size of the flask, as is the case in other molding machines, and therefore only the sand blower solves the problem of mechanizing the work of filling the flasks with molding material and compacting the latter in foundries, where individual work predominates. In addition, the sand blower has extremely high productivity.

The internal outlines of a part, voids, etc. are obtained using rods or cones, which are prepared separately from the molds in the so-called. core boxes. Since during the pouring process the cones are in most cases surrounded by molten metal, the issue of proper ventilation becomes extremely important: the gas permeability of the cones must be significantly higher than the gas permeability of the form itself. In fig. Figure 13 shows a drawing of a core (half of a core box).

To increase the gas permeability of the rod, a wax cord (cement) is placed inside it, the wax of which will melt during drying, leaving so. free passage for gas. To increase the resistance of the rod to the action of a column of molten metal, the rod is equipped with a special metal frame. For the production of such critical and complex castings, such as car blocks, radiators, etc., the so-called. oil rods, which are prepared in most cases from pure quartz sand with the addition of various binders for binding; Of these, linseed oil should be considered the best, but bean oil, maize oil, molasses, dextrin, gluten, etc. are also used. With the help of cones, you can obtain not only the internal, but also the external outline of the part ( flaskless molding). Many factories in America use this method, omitting all forming work and replacing it with core work, which does not require particularly skilled labor.

The manufactured forms are dusted with finely ground coal or graphite, or painted with a specially made mass ( beluga or paint), which is a very liquid mixture of refractory clay, flour and glue; When finishing molds for iron casting, fine graphite or coke is added to such a mass. Smoothing the surface of the mold with a smoothing iron is prohibited. After finishing, the mold is either placed in the dryer (more often) and collected for pouring, or (less often) it enters the pouring process in a raw form - wet casting. Drying of molds for different metals is carried out at different temperatures: for steel 500-600°C, for cast iron 200-300°C, for non-ferrous metals 150-250°C. Permanent and long-term molds are always slightly heated before casting (up to 75-100°C); then, for subsequent castings, on the contrary, they are cooled so that their temperature does not exceed 75-100°C. Particular care should be given to the issue of drying the rods, for which continuous dryers are successfully used, which make it possible to regulate the drying temperature within strictly defined limits with a fluctuation of ±5°C. Since the wet mold is more pliable than the dry one, often many castings that fail in the dry form succeed in the wet form. However, the green form requires special attention to the composition of the molding mass (large porosity is needed to remove not only gases released from the metal, but also water vapor) and proper compaction of the form. Do not over-compact (“ring”) and do not fill the molding mass too loosely (otherwise the liquid metal will wash away the walls of the mold) - a task that can only be solved by a very experienced worker.

Melting metal. Casting materials must have the following properties: a) fluidity, i.e. the ability of molten metal to fill the mold; b) minimal shrinkage, i.e. the ability of the casting to retain its shape; c) the least tendency to segregation; d) possibly low melting point. Almost all industrial metals(with the exception of aluminum) in their pure form do not satisfy these conditions: for example, iron has a very high melting point and has insignificant fluidity and high shrinkage; copper, although it does not have a very high melting point, but due to its excessively high tendency to dissolve gases, obtaining dense, bubble-free castings is very difficult and requires special conditions to avoid defective castings. Admixtures of other metals and metalloids to the base metal (iron, copper, etc.) significantly improve casting qualities in the sense of lowering the melting point, reducing the shrinkage coefficient, etc. An admixture of carbon to iron in an amount of 1.7% or higher lowers the temperature iron melting from 1528°C to 1135°C, shrinkage coefficient - from 2% to 1%; an admixture of zinc or tin to copper and aluminum significantly improves their casting qualities. Aluminum-copper and aluminum-silicon alloys have the best casting qualities. Steel for castings is used in two types: with a C content of 0.15 to 0.18% (tensile strength 36 kg/mm ​​2) and from 0.30 to 0.35% (54 kg/mm ​​2); Mn< 0,6-0,8%, Si < 0,20%; S и Р обыкновенно менее 0,05%. Этот состав обеспечивает плотность отливки. Специальные стали для литья применяются редко. В табл. 1 приводятся наиболее употребительные литейные сплавы алюминия.

To obtain a casting of the required qualities at the lowest cost, you need to know under what conditions the casting will work, what qualities will be required from it, and what changes will occur in the metal when it is remelted. Based on this, a calculation of the charge is made. In addition to the initial casting materials, the charge also includes foundry waste (grues, spurs, rejected castings, splashes from casting ladles, etc.) and scrap metal.

Below is an example of a numerical calculation of a charge (according to Moldenka) of acid-resistant gray cast iron (Table 2).

It is required to calculate the mixture of the following composition: 3.25% C, 1.53% Si, 1.25% Mn, 0.20% P, 0.05% S. For the calculation, certain values ​​of element loss during melting in a cupola furnace are taken. The task is to determine the relative quantities in which the cast irons of the groups must be mixedI,II and III to obtain a mixture of composition (in%): 1.82 Si, 1.91 Mn, 0.1 P, 0.016 S.

To do this, on the M axesn-Si (Fig. 14) we set aside the corresponding contents of Si and Mn; By connecting the points corresponding to the three cast irons (foundry lines 4, 5 and 6), we see that the point of the average composition of the required mixture is located inside the triangle I-II-III, which indicates the possibility of preparing the required mixture from these 3 types of cast iron. We connect the vertices of the triangle I-II-III to point O and continue the straight lines IO,IIO and IIIO until they intersect with the opposite sides of the triangle at points a, b and c.

Then we take an arbitrary straight line O 2 O 1 (Fig. 15), divided into 100 equal parts (100%), and at the ends of this straight line we draw straight lines 0 2 K and 0 1 L, parallel to each other, at an arbitrary angle. From point O 1, lay off the segments O 1 l, O 1 lI, O 1 III, equalO.I.OII, OIII. In the same way, from point O 2 we lay off straight lines O 2 a, O 2b and O 2 c, respectively equal to Oa, Ob and Os. Connecting points a with I, b withII and c with III, we will immediately read on the straight line O 2 O 1 that cast iron I should be taken 34%, cast ironII - 51% and cast iron III - 15%. Consequently, every 150 kg of charge will consist of 34 kg of cast iron I, 51 kg of cast iron II, 15 kg of cast iron III; 30 kg of your own scrap and 20 kg of purchased scrap.

For melting various metals, furnaces of various designs are used: for melting steel - open-hearth furnaces (acidic and basic), small Bessemer furnaces (for example, Tropenas, Robert); cast iron - cupola furnaces, reverberatory furnaces and crucible installations; for aluminum, copper and their alloys - various designs crucible, flame and electric furnaces. The cupola melting process is the most economical and therefore the most common; the use of crucibles is limited by the high cost of the process and the extreme inconvenience of producing castings (for example, steel shaped castings) from crucibles. Flame furnaces for non-ferrous casting are inconvenient because the oxidizing effect of the flame spoils the quality of the metal, and the metal oxides released in the room have a harmful effect on the health of workers; in addition, it is required that the pouring temperature of non-ferrous metals be within very narrow, predetermined limits (for example, for aluminum 700 ± 20 ° C). Recently, electric furnaces have become widespread various systems for melting ch. arr. steel and non-ferrous metals. The main advantage of electric furnaces is their indifference to the chemical reactions that take place during smelting, and, as a result, cleaner metal; then the ability to regulate, within a very wide range, the degree of overheating of the metal, its lower waste, etc. To melt cast iron, the use of electricity is much more expensive than melting in cupola furnaces, and therefore is relatively rare and only in the form of a combined process: cupola-electric furnace or cupola-furnace. Bessemer-electric furnace, in accordance with special requirements, presented by production. When melting non-ferrous metals in electric furnaces, the waste is reduced: for example, the waste of brass in crucibles is 4-6%, in electric furnaces 0.5-1.5%. In table Table 3 shows comparative data on the cost of melting 1 ton of brass in crucibles and electric furnaces of the Ajax system.

Casting technique. The supply of molten metal to the mold is one of the most important operations in foundry production; metal, perfectly composed (by analysis), molten and deoxidized according to all the best instructions, b. spoiled by inept putting it into shape. First of all, it is necessary to ensure that the stream of metal entering the mold is continuous and completely fills the channels supplying the metal to the mold. To do this, it is necessary to correctly calculate the mutual ratio of the cross sections of the gate, slag catcher and feeders (Fig. 16); So, with a gate diameter of 20 mm, the cross-sectional area of ​​the gate = 315 mm 2, the area of ​​the slag catcher should be taken smaller, namely 255 mm 2, and the sum of the areas of the feeders should not exceed 170 mm 2.

In fig. 17-22 show examples of correct and incorrect installations of gates, slag traps and feeders.

Fig. 17, 18 and 19 give examples correct installation, fig. 20 - incorrect installation because the cross-section of the sprue is too small and during casting the metal will not completely fill the slag trap, as a result of which slag will fall into the mold and spoil the casting. In fig. Figure 21 shows an incorrect installation: the sprue is placed directly above the feeder, the slag directly enters the mold. In fig. 22 the sprue is shifted and placed directly above the feeder, the slag falls into the mold. To avoid shrinkage cavities, two stops are placed in steel castings. Profits in steel castings take up about 25-30% of the weight of the casting. Small steel castings, cast iron (except for very critical ones) and non-ferrous castings are cast without profit. Filling molds requires some skill. Metal cannot be poured into the sprue with interruptions in the flow. In some cases, when high pressure is required, they try to direct a stream of steel from the ladle directly into the sprue, thus creating. strike of steel. The pouring of steel is considered complete when the metal appears in profit. At this point, in large castings, it is preferable to add metal in the margins, rather than through the sprue. That. a hot profit is created, feeding the casting (while reducing the volume of solidifying metal) from above, but not from below (which is harmful). It is recommended to deoxidize the finished metal with silica spigel before release. This additive makes the metal calmer and it pours well. Shrinkage cavities form in the thickest parts of the castings. The common view that the presence of shrinkage bubbles in castings reduces the strength of the metal is not always correct: a bubble enclosed in the metal is a sphere (like a dome) with regularly arranged crystals and exhibits significant resistance to destruction, especially crushing. Forging this bubble by forging forms a fold, the presence of which certainly weakens the metal. To avoid the formation of shrinkage bubbles, centrifugal casting and pressure casting are used.

Centrifugal casting involves introducing molten metal into a rapidly rotating metal mold, where centrifugal force causes it to adhere to the outer surface of the rotating mold. That. you can prepare a variety of bodies of rotation. The operating diagram of a centrifugal casting machine is shown in Fig. 23.

The form is cylinder A. By means of handle C, form A can be made. moved back (on the drawing - to the right). A piston at the end of the spindle with a cooling ribbed surface F forms the rear wall of the mold. At the beginning of the casting, mold A is pressed completely tightly against body B, after which ladle B filled with molten metal is rolled into mold D, which is simultaneously set into rotation. By turning handwheel E, molten metal is poured into the mold. As soon as the metal hardens, mold A is moved to the right onto the piston, which squeezes out the casting. The method of centrifugal casting in the manufacture of cast iron pipes has become particularly widespread. The material from which molds for centrifugal castings are prepared is selected especially carefully depending on the operating conditions of the centrifugal casting machine. For molds with a high degree of heating, cast iron, due to its tendency to grow (increase in volume with repeated heating), is not recommended; the use of steel gives better results. Molds without lining, heated or cooled by water, can be made of steel, but their service life is short. Therefore, it is preferable to make molds from nichrome (60% Ni and 40% Cr) or from Becket metal, as well as from an alloy of the following composition: 80% Ni and 20% Cr. This alloy can withstand prolonged and repeated temperature loads in excess of 1370°C. The essential requirement is that steel molds do not have cavities closer than 3 mm from the inner surface of the mold, and that this surface is completely smooth; The wall thickness is chosen so that during casting the mold does not heat up above the critical point of the given metal.

In injection molding, molten metal is injected under high pressure into a metal mold, resulting in parts that are so precisely sized that they require no further processing. machining. This represents particularly significant benefits for the mass production of small parts requiring high precision (eg meter parts, small machine parts). The most important industrial alloys for die casting are zinc, aluminum and, to some extent, copper alloys. In table Table 4 shows the characteristics of various alloys used for injection moldings.

The machines used for injection molding are divided into two main groups. 1) For alloys with a low melting point, piston machines are used (Fig. 24).

The liquid metal bath contains a pump driven by a lever or compressed air. When the piston moves down, the metal is pressed into the mold through the nozzle. Piston machines for alloys with a higher melting point (aluminum, etc.) turned out to be unsuitable: the metal hardens between the piston and the cylinder walls, which causes frequent cleaning and a sharp increase in overhead costs. 2) For refractory alloys, therefore, machines are used (Figs. 25 and 26) equipped with a special scoop (gooseneck), which, with the help of a special device, each time captures a strictly required portion of the metal; the metal is exposed to compressed air only in this scoop on a relatively small surface, thereby avoiding excessive oxidation of the metal.

Knocking out castings. The quickest release of the poured product from the molds has a significant impact on its integrity. It should also be borne in mind that a hot casting can easily be deformed by an awkward blow when being released from the mold. It is especially important to quickly release the central bumps of castings. For this purpose, when cones are made, part of the frame, which is the skeleton of the cone, is brought out through the “sign” so that after pouring with a sledgehammer, the cone can easily be knocked out along this protruding part and thereby allow the casting to contract freely during its further cooling.

The operation of knocking out flasks in modern foundries is completely mechanized. The simplest device for this purpose is to have a vibrator suspended from a pneumatic lift using a special device. attached to the flask, which at the same time rises slightly; After this, the vibrator is activated, and after a few seconds the flask is emptied. With another method of knocking out, the flasks are placed on a grid, which is set into an oscillatory motion with the help of cams; the earth from the flasks falls through the bars. To prevent hot soil from falling onto the soil conveyor belt in too large a mass, two feed rollers are installed under the grate, which evenly feed it onto the conveyor. Knocking out the rods is done either manually, or using a high-pressure water jet, or on specially designed pneumatic vibrator machines (Fig. 27) of the Stoney system.

Castings from the trolley are installed in special machine holders using an air lift located at each machine. Then the vibrator is activated, and the rods are knocked out for 3-6 seconds.

Casting cleaning. When removed from the mold, the casting has a number of bosses (sprues, thrusts and protrusions), which are unnecessary according to the product drawing, but necessary during production. The earth adhering to the casting, the sprues and the thrusts are removed by cutting off, and the profits by cutting off. A cleaned casting with profits is called black, and without profits - trimmed, or clean. Cast iron b. hours are left without pruning. Cleaning castings in some cases encounters difficulties, for example, during metal explosions, a “clog” occurs in the casting if the torn mass is not carried to the profit or vent; if the sprue is positioned incorrectly, the cutter can break out the sprue with the casting process; in this case, it is better to send the casting with the sprue for trimming; when removing deep cones, it is very difficult to select a thin cone from a long pipe; in this case, shifting the frame during the solidification of the metal can not only help maintain the integrity of the casting, but also facilitate knockout. Cleaning the outer surface of castings from burnt earth is carried out in modern foundries in rotating drums or with a stream of sand in sandblasting machines and chambers. The first method is mainly common in America, the second - in Europe. The disadvantage of the method of cleaning castings in ordinary drums is the large expenditure of labor and time for manual loading and unloading. A significant simplification is obtained if continuous drums are used instead of ordinary drums (Fig. 28).

The drum has internal and external cavities. The castings enter the internal cavity of the rotating drum from the right side. Hardened cast-iron sprockets enter there from the outer cavity through special slots. By moving slowly towards the opposite end of the drum, the casting has time to clean itself. Before reaching the end of the drum, the cast iron sprockets fall through small slots from the inner to the outer cavity of the drum, from where they are transmitted through spiral guides to the head of the drum. Castings that are more complex, when cleaning in drums one could be afraid of a large percentage of defects due to breakage and which are subject to significant mechanical processing, are cleaned in continuous sandblasting chambers. The method of hydraulic cleaning of castings, first successfully used at the Allis Chalmers Co. plant, turned out to be very successful. (Millwaukee): Cleaning time has been reduced from hours to minutes. The device is used for cleaning turbine wheels, gasometer cylinders and similar heavy castings. Cleaning of castings is carried out in a closed concrete chamber (Fig. 29), located in the middle of the casting room.

The internal dimensions of the chamber are 10370x18725x6100 mm. The thickness of the concrete walls is 305 mm. To protect the walls from the eroding effect of water, they are covered with steel plates. Inside the chamber there are two turntables with a diameter of 3050 mm (lifts 100 tons) and 6100 mm (300 tons). Both circles rotate on ball bearings and are driven by 25 and 35 HP motors. The service room is located in one of the corners of the chamber. There are 2 devices installed with three nozzles located at equal heights. Nozzles m.b. placed at any height. The nozzle for the larger table has a diameter of 27 mm, for the smaller one - 16 mm. The pump with a capacity of 3500 l/min is driven by a 300 HP motor. With two simultaneously operating nozzles, the water pressure is 28 atm. The dirt resulting from cleaning settles in two receptacles under the floor, from which it is continuously removed using an elevator. The earth is separated from the water, brought to 7% humidity and put back into production. The advantage of this cleaning method is its low cost, complete absence of dust, and also the fact that the rod frames do not deteriorate and can be used again.

Heat treatment. After cleaning, the casting is sometimes subjected to heat treatment. Cast steel and malleable cast iron must be annealed. Regarding cast iron, it has now been proven that it can. subjected to heat treatment similar to steel, and the ferrite-graphite-cementite structure of cast iron transforms into a pearlite-graphite structure with an increase in mechanical properties (elongation up to 8%, tensile strength up to 40-45 kg/mm ​​2). Heat treatment is especially facilitated by casting cast iron into permanent molds. Bronze casting can also be used in many cases. improved by heat treatment. Aluminum casting is always hardened at 500±10°C and tempered at 140±10°C.

Basic principles of foundry design. When designing a new foundry, you first have to take into account the location of the main metalworking shops and choose a location for the foundry in such a way as to be able to most easily and cheaply deliver castings to the processing shops. Foundry work program determined with the most accurate details possible, both in quantitative and weight terms, and in dimensional terms, which will make it possible to select the most suitable equipment for a given case and the most appropriate technological process. The foundry calculation scheme in this case is reduced to the following. Having a precise program of work, they compile an album of moldings, which will give the basic principles for organizing individual operations of the technological process and the number of flasks required for production and their types, as well as the required amount of molding materials, and therefore the power of the agricultural device. Having received it like this. arr. approximate data on the consumption of raw materials, on the size of the required space, begin to clarify individual operations of the production process, its possible mechanization as a whole or in individual parts. Various options for calculating the relative position of individual foundry shops will make it possible to most expediently resolve the issue of organizing a given production process. If the program does not m.b. defined with b. or with acceptable accuracy, then it is necessary to calculate the main and auxiliary workshops of the foundry using the so-called coefficients. In fig. 30 shows the usual types of foundry buildings;

fig. A - gray cast iron foundry for individual casting; B - malleable cast iron foundry with installation of flame furnaces; B - shaped steel foundry with open hearth furnace department; G - shaped steel with converters; D - steel foundry with electric furnaces.

Occupational hazards and safety precautions. All production processes taking place in foundries are associated with the occurrence of certain occupational hazards. Thus, during the preparation and processing of molding materials, knocking out, cutting and cleaning of castings, a huge amount of dust is generated (from 20 to 180 mg/m3). Proper ventilation must be installed to control dust pollution; Particularly favorable in this regard is the use of a hydraulic method for cleaning castings. During molding work, in cases where molding is carried out on the foundry floor, workers are forced to keep their body bent, often in a very unnatural position, which can lead to curvature of the skeletal bones. These hazards are eliminated during work on molding machines. Low temperature in foundries winter time(often below 0°C), high dampness, always cold and often frozen earthen floors cause frequent colds among molders, especially rheumatism. When servicing melting machines, workers are exposed to the harmful effects of sudden temperature fluctuations. When casting, molten metals release harmful gases. From the latest highest value have the following: carbon monoxide, sulfur dioxide and zinc oxide. The concentration of CO in the air of foundries fluctuates on average within the range of 0.03-0.05 mg/l, reaching 0.21-0.32 mg/l at certain moments of casting above the flasks. (The Institute of Occupational Safety and Health has set a standard of 0.02 mg/l.) The amount of sulfur dioxide (SO 2) in the air of foundries, depending on the type of metal and coke used, reaches 0.045-0.15 mg/l (standard 0.02- 0.04 mg/l). Inhalation of zinc oxide vapors in copper foundries causes attacks of foundry fever in workers. When manually filling the charge into melting machines, when pouring metal into flasks manually, extremely high muscle tension is observed, which, due to high temperature work causes severe sweating. These hazards are eliminated by the use of conveyors, mechanization of loading furnaces and transport, as well as pneumatic knocking out of flasks.

The largest number of accidents in iron and copper foundries occurs from burns from molten and hot metal during manual handling or delivery. Especially serious consequences entails contact of molten metal or slag with moisture (explosions). To eliminate these phenomena, it is necessary to have smooth paths made of brick, concrete, reinforced concrete, etc. in places not occupied by molding, and the main passage should be. not already 2 m; d.b. the flow of people with empty ladles and molten metal is correctly organized; places where castings and slag are poured must be dry; buckets d.b. well dried and heated; Ladle casings should have small holes to remove vapors from the coating, etc. Workers handling molten metal should b. equipped with proper protective clothing, goggles, respirators, etc., and the shirt should not be tucked into pants and pants into boots, and the brim of the hat should not be tucked into pants. bent down. Hand molding is accompanied by a large number of pins on the iron pins present in the old molding soil. The remedy is to pass the earth through a magnetic separator. When carrying ladles with molten metal, their center of gravity must be below the axis of rotation (up to 50 mm) to avoid tipping over. All chains, ropes and rockers must be tested to full load at least once every 2 months and thoroughly inspected at least once every 2 weeks. All machines must be equipped with reliable guards for hazardous areas.

To legally regulate working conditions in foundries, the People's Commissariat of Labor issued a number of mandatory decrees. This primarily includes the “Safety Rules for Work in Iron and Copper Foundries”; resolutions on limiting the use of labor of women and adolescents in the most harmful and hazardous work in foundries; decisions on shortened working hours and additional leave for certain categories of workers (copper foundries, sandblasters, etc.).

Federal State Educational Institution of Higher Professional Education "Ural Federal University named after the first President of Russia B.N. Yeltsin"

Institute of Materials Science and Metallurgy

Department of Foundry and Hardening Technologies

Lecture notes on the discipline "Foundry"

Lecture 1

Basic concepts of foundry production

Lecture outline

1. The concept of foundry production.

2. Brief historical overview of the development of foundry production. The role of Russian scientists in development scientific foundations and organization of production of castings and ingots.

3. Classification of casting alloys and their areas of application.

It is impossible to imagine modern life without metals. Metals are the basis of technical progress, the foundation of the material culture of all mankind. But metal becomes useful to a person only when products are made from it. There are three main types of production of metal products. These are foundry, metal forming and metal cutting. The course "Foundry" is devoted to the first type of metalworking.

This lecture notes discusses in sufficient detail the theoretical foundations of foundry production, in addition, it describes the technological processes for producing various products and the equipment and tools used in this process.

Lecture notes are devoted to the foundry production of ferrous and non-ferrous metals. It outlines the fundamentals of the theory, technological processes and equipment designed to produce castings in various ways (in one-time sand-clay molds, lost-wax molds, in a mold, under pressure, etc.).

When presenting the material, the main attention is paid to the consideration of the physical and physico-chemical essence of the processes of a particular technology, the design features of equipment, the purpose of technological modes, the equipment used and automation equipment.

Along with the presentation of specific material for each technological method of producing blanks, special attention is paid to the main bottlenecks, problems of technological processes, analysis of ways and means of solving them to obtain products of a given quality and achieve high production efficiency; Based on the same approach, the prospects for the development of each process are considered.

Foundry concept

The essence of foundry production comes down to obtaining liquid, i.e. heated above the melting point, an alloy of the required composition and quality and pouring it into a pre-prepared mold. After cooling, the metal hardens and retains the configuration of the cavity into which it was poured. Thus, to make a casting, you must:

1) determine the materials that need to be introduced into the charge for smelting, calculate them, prepare these materials (cut them into pieces, weigh out the required amount of each component); load materials into the melting furnace;

2) carry out melting - obtain liquid metal of the required temperature, fluidity, proper chemical composition, without non-metallic inclusions and gases, capable of forming a fine-crystalline structure without defects with sufficiently high mechanical properties upon solidification;

3) before the end of melting, prepare casting molds (for pouring metal into them) that are capable of withstanding the high temperature of the metal, its hydrostatic pressure and the erosive effect of the jet, without breaking, and also capable of passing gases released from the metal through pores or channels;

4) release the metal from the furnace into the ladle and deliver it to the casting molds; fill the casting molds with liquid metal, avoiding interruptions in the flow and preventing slag from entering the mold;

5) after the metal has hardened, open the molds and remove the castings from them; PRODUCTION

6) separate from the casting all the sprues (metal frozen in the sprue channels), as well as the ridges and burrs formed (due to poor-quality pouring or molding);

7) clean the castings from particles of molding or core sand;

8) carry out quality control and size control of castings.

Currently, the largest number of castings are produced in one-time (sand) molds, made from a molding mixture consisting of quartz sand, refractory clay and special additives. After the metal has hardened, the mold is destroyed and the casting is removed. In addition to one-time ones, semi-permanent molds are used, made of highly refractory materials (chamotte, graphite, etc.), they are used to fill several dozen (50–200) castings, and permanent molds are metal, they are used to produce several hundreds, and sometimes thousands castings until the mold wears out. The choice of casting mold depends on the nature of production, the type of metal being poured, and the requirements for casting.

A brief historical overview of the development of foundry production. The role of Russian scientists in the development of scientific foundations and organization of production of castings and ingots

Foundry is one of the most ancient forms of metalworking art with which humanity has become acquainted. Numerous archaeological finds discovered during excavations of mounds in various points of our country indicate that in Ancient Rus' Copper and bronze castings were produced in fairly large quantities (bowlers, arrowheads, jewelry - earrings, wrists, rings, hats, etc.). During the excavations, surviving forges and furnaces, stone molds were discovered that were used for casting hollow axes, rings, bracelets, metal beads, crosses, etc. However, most of the castings found in Ancient Rus' were obtained by casting from a wax model.

The method of making the model was original: a pattern was woven from wired cords, representing a copy of the future product; Clay was applied to this wax model until a sufficiently strong mold was obtained; after drying, the mold was calcined, the wax was melted, and the cords burned out; metal was poured into the resulting cavity; after cooling, a casting of complex shapes was obtained.

In the 11th century In Rus', local production centers arose for the casting of church (copper crosses, bells, icons, candlesticks, etc.) and household (kettles, washstands, etc.) items. In addition to Kyiv and Novgorod the Great, Ustyug Veliky and Tver became major centers for the production of copper-cast products. The Tatar invasion caused stagnation that lasted until the middle of the 14th century, after which the rise of foundry production began. This is explained by the fact that a centralized large state was created, in connection with which cities began to develop and weapons were required, now firearms. They switched from the production of welded cannons to cast bronze ones, cast bells, and created copper foundry workshops for artistic casting. By the middle of the sixteenth century. Moscow artillery occupied quantitatively first place among the artillery of European states.

The Peter the Great era represented a leap in the development of foundry production. Large Tula and Kaluga factories were created by Nikita Demidov and Ivan Batashov. The first steel castings were produced in the second half of the 19th century. almost simultaneously in various European countries. In Russia they were made in 1866 from crucible steel at the Obukhov plant. However, the quality of the castings turned out to be low, since the casting properties of steel were significantly inferior to those of cast iron. Thanks to the work of Russian metallurgists A.S. Lavrova and N.V. Kalakutsky, who explained the phenomena of segregation and presented the mechanism of occurrence of shrinkage and gas cavities, and also developed measures to combat them, the advantages of steel castings were fully revealed. Therefore, the shaped castings obtained by A.A. Iznoskov from open-hearth steel at the Sormovo plant in 1870 turned out to be of such high quality that they were demonstrated at an exhibition in St. Petersburg.

After release scientific works the founder of metallography D.K. Chernov, who created the science of transformations in alloys, their crystallization, structure and properties, began to use heat treatment, which improved the quality of steel casting. The theory of metallurgical processes was introduced in higher school by A.A. Baikov in 1908 at the St. Petersburg Polytechnic Institute. In the period from 1927 to 1941. There is an unprecedented growth in industry for former Russia, and the largest mechanized factories are being built. Foundries are being built and put into operation, operating in a continuous flow mode, with a high degree of mechanization, with conveyors, with an annual output of up to 100 thousand tons of castings.

At the same time, research work is carried out, theories of work processes and methods for calculating foundry equipment are created. A scientific school of the Moscow Higher Technical School is being formed, founded and headed by prof. N.P. Aksenov.

The widespread use of foundry production is explained by its great advantages over other methods of producing blanks (forging, stamping). Casting can produce workpieces of almost any complexity with minimal processing allowances.

In addition, the production of castings is much cheaper than, for example, the production of forgings. The development of foundry production to this day has taken place in two directions:

1) development of new casting alloys and metallurgical processes;

2) improvement of technology and mechanization of production.

Great progress has been made in the field of studying and improving the mechanical and technological properties of gray cast iron - the most common and cheapest casting alloys. Special types of casting are becoming increasingly widespread and improved: chill casting, pressure casting, shell molding, lost-wax casting, etc., ensuring the production of accurate castings and, therefore, reducing the cost of cutting processing.

Classification of casting alloys and their areas of application

On average, cast parts account for about 50% of the mass of machines and mechanisms, and their cost reaches 20–25% of the cost of the machines. Depending on the method of producing cast billets, alloys are divided into cast and deformed. Casting alloys are either prepared from initial components (charge materials) directly in foundry, or are obtained from metallurgical plants in finished form and are only melted before being poured into foundry molds. In both the first and second cases, individual elements during the smelting process can oxidize (burn out), volatilize at elevated temperatures (sublimate), enter into chemical interaction with other components or with the furnace lining and turn into slag.

To restore the required composition of the alloy, the loss of individual elements in it is compensated by introducing into the melt special additives (ligatures, ferroalloys) prepared at metallurgical enterprises. Alloys contain, in addition to the alloying element, the base metal of the alloy, so they are more easily and completely absorbed by the melt than a pure alloying element. When melting alloys of non-ferrous metals, master alloys are used: copper-nickel, copper-aluminum, copper-tin, aluminum-magnesium, etc.

When casting ferrous alloys, ferroalloys (ferrosilicon, ferromanganese, ferrochrome, ferrotungsten, etc.) are widely used to introduce alloying elements, as well as to deoxidize the melt. During the deoxidation process, the elements contained in ferroalloys act as reducing agents: they combine with the oxygen of the oxide dissolved in the melt, reduce the metal, and, having oxidized, they themselves turn into slag. Purification (refining) of the melt by deoxidation helps to significantly improve the quality of the cast metal, increasing its strength and ductility. A number of alloys, as well as non-metallic materials (salts, etc.) are used as modifiers, which, when introduced into a cast alloy in small quantities, significantly affect its structure and properties, for example, they refine the grain and help increase the strength of the metal. Thus, to obtain high-strength cast iron, modification with magnesium is used.

The main quality criteria for cast metal are mechanical properties, structure indicators, heat resistance, wear resistance, corrosion resistance, etc., specified in the technical requirements.

Alloys are usually divided, like metals, primarily into ferrous and non-ferrous, the latter also including light alloys. Alloys are divided into groups depending on which metal is the base of the alloy.

The most important groups of alloys are the following:

cast irons and steels – alloys of iron with carbon and other elements;

aluminum alloys with various elements;

magnesium alloys with various elements;

bronze and brass are alloys of copper with various elements.

Currently, alloys of the first group are most widely used, i.e. ferrous alloys: about 70% of all castings by weight are made from cast iron and about 20% from steel. The remaining groups of alloys account for a relatively small part of the total mass of castings.

The chemical composition of an alloy distinguishes between the main elements (for example, iron and carbon in cast iron and steel), permanent impurities, the presence of which is due to the production process of the alloy, and random impurities that have entered the alloy due to one reason or another. Harmful impurities in steel and cast iron include sulfur, phosphorus, ferrous oxide, hydrogen, nitrogen and non-metallic inclusions. Harmful impurities in copper alloys are cuprous oxide, bismuth and, in some of them, phosphorus. Admixtures of aluminum and iron sharply worsen the properties of tin bronze, and in aluminum bronze, on the contrary, tin. Aluminum alloys should have a limited iron content, and magnesium alloys should also have a limited content of copper, nickel and silicon. Gases and non-metallic inclusions in all alloys are harmful impurities.

The requirements for each casting alloy are specific, but there are a number of general requirements:

1. the composition of the alloy must ensure that the specified properties of the casting are obtained (physical, chemical, physicochemical, mechanical, etc.);

2. the alloy must have good casting properties - high fluidity, non-saturation with gases and the formation of non-metallic inclusions, low and stable shrinkage during solidification and cooling, non-propensity for segregation and the formation of internal stresses and cracks in castings;

3. the alloy should be as simple as possible in composition, easy to prepare, not contain toxic components, and not emit highly polluting substances during melting and pouring environment products;

4. the alloy must be technologically advanced not only in the manufacture of castings, but also in all subsequent operations of obtaining finished parts (for example, during cutting, heat treatment, etc.);

5. the alloy must be economical: contain as little as possible the number of expensive components, have minimal losses when processing its waste (sprues, scrap).

Test questions and assignments

1. What is the history of the development of foundry production in Russia?

2. What is the role of Russian scientists in the development of scientific foundations and organization of production of castings from alloys of ferrous and non-ferrous metals?

3. What are the methods for producing castings?

4. What molds can be used to produce shaped castings?

5. How are casting alloys classified?

6. What are the requirements for casting alloys?

7. List the main areas of application of casting alloys.

8. What is the essence of foundry technology?

Business meetings were held in the Urals in September Dutch companies with the Russians potential partners. The partnership was proposed for various industries: metallurgy, mechanical engineering, Agriculture, food industry. The crisis disasters that affected the Urals, like all regions of the Russian Federation, did not frighten European industrialists. And this is a good sign!

Despite the fact that the Urals are in decline today, we need to think about the future, says Marina Bogdanova, business development manager at GEMCO CAST METAL TECHNOLOGY. - When the economy starts to develop again, it may already be too late. In Russia, the foundry industry is represented mainly by foundries that are part of machine-building and other manufacturing corporations and holdings, and relatively a small amount independent foundries. In this situation, foundry production for the company as a whole is often perceived as auxiliary, and therefore “eating up” the company’s funds. Hence the residual sign of capital investment in development. Over the course of decades, this approach has led to almost universal moral and technical obsolescence of equipment and technologies. Point-by-point attempts to improve and modernize do not give the desired effect.

As a result, in the industry as a whole we have high-cost, inefficient, poorly organized production, which weighs heavily on the shoulders of companies. Meanwhile, everything should be the other way around. Foundry production is a business where you can and should make money. How to make this possible? Naturally, serious capital investments are required. But besides this, and no less important, we need a highly professional approach to mastering such tools. Purchasing new equipment is not everything; here you need to solve a complex of problems. Namely, the choice of equipment should be optimal, so as not to spend extra money on excess capacity, and at the same time not create a shortage of capacity. It is necessary to build an optimal production scheme, optimally organize manufacturing process. This will significantly reduce costs, make it possible to recoup capital investments within 4-5 years, and bring production to the level of an independent business that brings good profit. Today, the winner in the market is the one who offers high quality at a low price. However, this task is not an easy one. GEMCO, which has a staff of professionals who have accumulated relevant experience and knowledge, knows how to achieve such a combination.

Marina, what, first of all, does a production worker really care about: profit or quality?

This issue cannot be divided. These two concepts depend on each other. They are inseparable. If a company produces low quality products, what are the benefits? we're talking about? The owner of the company can increase quality, at the initial stage at a loss, and establish himself. Or maybe lower it, but there is a risk of losing customers. The profitability of an enterprise depends on sales volume. You made a successful batch, they bought it from you - you have proven yourself. This is how business connections are built. Quality - reputation - sales - benefits .

Russia has long been among the countries where any activity is specific. This requires a special approach. However, the Dutch are no strangers - they know how to professionally and effectively remove Russian company to the leaders.

What tools does the company offer to solve problems in foundry production?

Our company is engaged in foundry production: ferrous and non-ferrous. The activities of GEMCO CAST METAL TECHNOLOGY are divided into three components. Engineering: includes the development of a foundry project and the stages of its implementation. Contracting: general contracting. Foundry consulting, which can be operational or strategic. Operating is marketing research according to customers, comparative analysis production efficiency. This may include technical and commercial audits required for mergers and acquisitions. Operations consulting involves developing methods to improve production. When an enterprise has been operating for a certain time, it is necessary to periodically monitor production efficiency.

It comes back to strategic planning, the absence of which our entrepreneurs often sin. In this case, precisely calculated technical and economic aspects are simply necessary. After all, in order to get the expected result, you need to act correctly at each stage.

Marina, your company is called unique. For what?

There are companies on the market that provide only engineering, or only consulting, or specializing in the supply of equipment. What makes GEMCO unique is what we provide A complex approach. And our customers will confirm to you our accuracy and responsibility.

Tell us your step-by-step approach to the project

First, you need to consider aspects of the future project that the company is going to release. Based on them, a production concept is made, the technical part is drawn up and preliminary layout is carried out. Then the project begins to fill up necessary equipment according to needs. There is no point in installing equipment that cannot support production volumes or that will not be used 100%.

Next, we calculate resource costs: how much gas, water, energy, raw materials are needed, how many people should service the line. This is the concept. After completing the above work, we calculate how much the entire project will cost.

For example, what specific advantage can you give to the customer’s company?

For example, creating a team. It is very important. If a company does not have a team, it is doomed to failure. Uniting technologists, metallurgists, and working operators is not an easy matter. Let's say the company used long time“casting into the ground” technology and management decided to introduce New Product. And for this we need another technology that has not yet been mastered. It is we who will carry out the transfer of technology: we will select personnel for professional requirements, we will define the responsibilities for each team member, train and, most importantly, monitor the implementation of the process.

What is the current state of the foundry industry in the Netherlands?

To answer this question, you need to trace the situation ten years ago. During this period of time, major changes occurred. Some businesses closed, many were moved to new locations. Over the past 10 years, there has been a tendency to concentrate on narrow-range products. Now in Russia the same topic is just beginning. There are many such industries in the Russian Federation. Now the attitude towards foundry production is as auxiliary, as ballast, but everything must change.

In the Netherlands, the crisis is almost over. This is not to say that everything is great, because... there are problems that require solutions. Many companies have suspended operations. And, interestingly, part of the vacated market has already been occupied. Roughly, everything will return to normal in about two years. But for Russia the time frame is longer. And if we knew the answer to the question “When will the crisis end?” - they wouldn’t tell it to anyone, but use it for themselves. In the Netherlands this is several months, for Russia it is years. There are still banking problems and bureaucratic barriers, but it is the task of the state to create conditions. in which people wanted to do something.

You held meetings with Ural businessmen, but now the situation is so unstable. Do you think today is the time for new projects?

There is a concentration of such companies in Chelyabinsk, but today a serious modernization of production is needed. Management understands this and is working in this direction. Unfortunately, the process takes longer than we would like.

GEMCO CAST METAL TECHNOLOGY's early activities were related to the manufacture of equipment for foundries, but practice has shown that it is necessary to focus on intellectual activity. There is such a thing in business - finding your niche. We found her. It is important that there are people who will help you professionally understand the issues of using the most economically and technically effective production solutions, carry out the optimal selection of equipment, determine the technological process and movement of materials, and effectively use investment capital. I would like to emphasize that we will provide a realistic overview of the required investment and project timeline; We will give an objective definition of the price level of products and financial indicators.