annotation
Introduction
1. General part
2. Design part
3.1.7 Block control
3.2.3 Degreasing model blocks
3.2.4 Application of ceramic coating
3.2.5 Drying blocks
3.2.6 Removing model mass
3.2.7 Calcination of shell molds
3.2.8 Regeneration of ceramic coating
3.2.9 Molding of shells in a flask
3.3 Justification for choosing an alloy for a given casting
3.3.1 General approaches to alloy selection
3.3.2 Mechanical and casting properties of the alloy
3.4 Melting and pouring of alloy
3.5 Cooling
3.6 Cleaning the casting from ceramics
3.6.1 Punching molds and beating ceramics
3.6.2 Cutting off the gating system
3.6.3 Blowing the casting with electrocorundum
3.7 Cutting and welding of defects, cleaning
3.8 Quality control of castings
3.8.1 Control of the chemical composition of the alloy
4. Organization of equipment and accessories repair service
5. Calculation of workshop area
6. Warehousing
6.1 Calculation of warehouse space
7. Organization of cargo flows in the workshop
8. Construction part
8.1 Building structural elements
9. Organizational and economic part
9.1 Technical level of production
9.2 Organization of production and management
9.4 Calculation of the wage fund for workshop personnel
9.5 Calculation of the cost of fixed assets
9.6 Calculation of additional capital costs
9.7 Calculation of material costs
9.8 Calculation of energy costs
9.9 Shop cost estimate
9.10 Production cost estimate
9.11 Main technical and economic indicators
9.12 Calculation of the economic efficiency of introducing new equipment and technology
10. Safety and environmental friendliness of the project
10.1 Ensuring workplace safety
10.2 Identification and analysis of hazardous and harmful production factors
10.2.2 Organization of ventilation
10.2.3 Organization of heating of production and office premises
10.2.4 Organization of industrial lighting
10.2.5 Noise and vibration
10.3 Measures to reduce the harmful effects of the considered HFPFs
10.4 Calculation of dust load
10.5 Ventilation calculation
Special part of the final qualifying work
Introduction
11. Review of literature sources
11.1 Pistol-type syringes for pressing in the model composition
11.2 Installation with a gear pump for preparing the model composition and making models
11.3 Pneumatic table press
11.4 Installation for pressing in model mass
11.5 Syringe machine model 659A
11.6 Conclusion of the literature review
11.7 Modernization of the installation for pressing model mass
11.7.1 Description of the operation of the modernized installation for pressing model mass
11.8 Analytical calculation of the device’s operating process
11.8.1 Compressed air consumption for pressing one mold
11.8.2 Selection of gear pump
11.8.3 Calculation of heating elements
Conclusion
List of used literature
annotation
This paper presents a project for an investment casting workshop with a capacity of 120 tons per year.
The explanatory note of the project includes: the general part, the design part, the technological part, the construction part, the organizational and economic part, a description of the warehouse, the organization of cargo flows in the workshop and the labor protection section.
The general part describes issues such as: selection and justification of the production method and process manufacturability; purpose and characteristics of the designed workshop with a flow diagram of the technological process; workshop production program; modes and funds of operating time of equipment and workers.
The design part addresses the following issues: analysis of the manufacturability of the part design; development of technology for producing LPVM castings; development of the drawing "Elements of a casting mold"; calculating the gating system; development of a casting drawing, design of a model mold; assessment of the economic feasibility of the developed technology and calculation of the yield, metal utilization rate, and workpiece utilization rate.
The technological part includes: transport and technological diagram of the workshop; description of processes, equipment, technologies and production program of various departments of the workshop: melting and casting, heat-cutting, casting control laboratories, repair service of the workshop.
The construction part provides the rationale for the construction of premises for the areas and the unification of the building elements used in the arrangement of the workshop.
The organizational and economic part presents an economic assessment of the designed workshop, revealing such issues as: organization of production and management, calculation of the number of workshop personnel by category, calculation of wage funds, calculation of the need for working capital, calculation of material costs, calculation of production costs, calculation of cost estimates for the maintenance and operation of equipment, calculation of estimates of general workshop costs, estimates of production costs, calculation of the cost per unit of production, technical and economic indicators of the designed workshop.
The following issues are considered: organizing the workshop's warehouse facilities, organizing cargo flows in the workshop, and labor protection.
project workshop casting part casting
Introduction
In this work, we are developing a technology for producing a casting of the “Matrix” part . A justification is made for the manufacturability of the design and the method of production of the casting. In 1940-1942. The development of the lost-wax casting method began. This is mainly due to the need to produce aircraft gas turbine engine (GTE) blades from difficult-to-process heat-resistant alloys. At the end of the 40s, the production of various small, mainly steel castings using lost wax models, was mastered, for example, for motorcycles, hunting rifles, sewing machines, as well as drilling and metal-cutting tools. As the process developed and improved, the design of lost wax castings made became more complex. In the early 60s, large solid-cast rotors with a bandage ring were already manufactured from heat-resistant nickel-based alloys. The modern period of development of lost wax casting production is characterized by the creation of large mechanized and comprehensively automated workshops designed for mass and serial production of castings. The most appropriate method of casting such parts is lost wax casting, since the castings have a high degree of configurative accuracy and are as close to the parts as possible. Metal waste in chips for cast workpieces is 1.5-2 times less than for parts made from rolled products. Cast billets have a lower cost than other types of billets. The industrial application of this method ensures the production of complex-shaped castings weighing from several grams to tens of kilograms from any foundry alloys with walls whose thickness in some cases is less than 1 mm, with a roughness from Rz = 20 μm to Ra = 1.25 μm (GOST 2789-73) and increased dimensional accuracy (up to 9-10 qualifications according to GOST 26645-88). Casting can produce workpieces of almost any complexity with minimal processing allowances. This is a very important advantage, since reducing cutting costs reduces the cost of products and reduces metal consumption. Since the “Matrix” has a complex geometric shape, which is difficult and impractical to obtain by mechanical processing, and the casting material is difficult to process, therefore the workpiece must be obtained with a minimum allowance, it is produced by investment casting. It is not advisable to use any other method. The disadvantage of this type of casting is the low mechanization and automation of technological processes. The purpose of this work is to develop a technology for producing the “Matrix” casting using lost wax casting. 1. General part
1.1 Workshop production program
The production program of a foundry shop is calculated on the basis of the given workshop capacity in tons of suitable castings, the selected range of castings and their quantity per standard machine set. The designed investment casting shop has an annual capacity of 120 tons, the range of castings selected is 6 types: Table 1.1 - Parameters of selected parts Name Weight of part, kg Weight ex., kg Pieces. per product Weight per product, kg Die 1218118 Frame 2543143 Punch 1620120 Ring 4060160 Flange 3560160 Bearing housing 4275175 Total: 170276276 Number of castings to complete the annual program: Where M- annual capacity of the workshop, t; Casting weight, t; ki- number of castings per product, pcs. Number of castings per product: where - defects of machine shops, 5% (from casting to product)); α
salary- casting for spare parts, 10% of casting for the product. Weight of castings per product: Number of castings for spare parts: Mass of castings for spare parts: Number of castings for defective machine shops: Mass of castings for scrap in machine shops: The calculation results are shown in table 1.2 Based on the data from the workshop's production program, a metal balance is compiled, which in turn is the production program of the smelting department. The metal balance for the workshop is calculated using the following formulas: Weight of sprues according to the program: where is the weight of the casting with the gating system, i.e. Mass of castings for technologically inevitable defects: where is a technologically inevitable casting defect, % Mass of castings for technological losses: where is the percentage of technological losses associated with transportation and casting of metal, as well as with equipment changeover Mass of liquid metal: Mass of burnt metal: where is the loss of charge elements during smelting, %; Metal filling: The calculation results are shown in Table 1.3 To calculate the production program of the lost wax casting departments, it is determined how many products within the technological process must be manufactured, taking into account all technological losses. To take into account technologically inevitable defects and losses, technological loss coefficients are introduced, which are calculated by department and take into account losses and defects not only for operations in the department, but also for all subsequent operations. Number of model blocks per program: Number of models in the block. Weight of model composition per model: where is the density of the model composition and casting material, g/cm3. Weight of the model composition per block: where is the volume of the gating system and model riser, dm3. Weight of model composition per program: Number of model blocks per program, taking into account losses: Where R4
= 1.42 - coefficient of technological losses for the production of model blocks. Number of model personnel per program, taking into account losses: Number of shells per program, taking into account losses: Where R3
= 1,2 -
coefficient of technological losses for the manufacture of molds. Amount of suspension per program, taking into account losses: Where Vf- volume of the shell mold, m3, Brsus = 0.5% - losses during the production of the suspension. Number of casting blocks per program, taking into account losses: Where R2
= 0,6 -
coefficient of technological losses for the production of casting blocks. Number of castings per program, taking into account losses: Where R1
= 1,1 -
coefficient of technological losses during cutting and finishing of castings. Weight of castings per program, taking into account losses: Metal loading per program taking into account losses: Where α
y, tp -
the total percentage of waste and technological losses. The calculation results are given in Appendix A, in tables 1 and 2.
1.2 Workshop structure. Transport and technological scheme
The entire technological process of manufacturing castings, from receiving models to shipping finished castings, is carried out in one workshop. The workshop consists of four main production divisions: .Model; 2.Department for the production of shell molds; .Melting and pouring; .Obrubnoe. The premises of a foundry for the production of investment castings include: production, auxiliary and storage facilities. The auxiliary department consists of areas for the preparation of the charge, the preparation of the refractory mass, waste removal, repair services of the shop mechanic and power engineer, a transformer and pumping station, ventilation and dust removal units, control panels, instrumental and workshop laboratories. Warehouses of the casting shop for lost wax models: model mass, molds, refractories, shop mechanics and power engineers, finished castings, storerooms for auxiliary materials. 1.3 Working hours and time funds
In the designed investment casting workshop, a parallel mode of operation of the workshop is used (all technological operations for the manufacture of a product occur in parallel to each other). The range of parts is shown in Table 1.1. In accordance with the Labor Code, the working week for workers at machine-building plants, including foundries, is 40 hours, with a shift duration of 8 hours, and on holidays - 7 hours. When designing, three types of annual operating time funds for equipment and workers are used: ) calendar FTo= 365× 24=8760 hours ) nominal Fn,
which is the time (in hours) during which work can be performed according to the accepted regime, without taking into account inevitable losses; ) valid Fd, determined by excluding from the nominal fund the inevitable losses of time for normally organized production. With a 40 hour work week Fnis 3698 hours when working in two shifts, 5547 hours when working in three shifts. For determining Fdoperation of equipment from Fnconditionally exclude the time spent by equipment under scheduled repairs established by the standards of the system of scheduled preventive maintenance. Equipment downtime caused by deficiencies in production organization for external reasons, when determining Fdare not taken into account. All design work is carried out relatively Fdoperation of equipment and workers. The operating mode of the designed workshop must correspond to the operating mode of the enterprise. This workshop is designed to operate in two and three shifts. The results of calculating time funds for the designed workshop are given in Tables 9.1 and 9.2. When calculating the working time fund of one worker, in addition to the three above-mentioned time funds, the so-called effective time fund is used, which takes into account the loss of working time associated with leaves (regular, administrative, study, illness, due to childbirth), as well as with various government duties. Calculation Fefone worker is presented in Table 9.3. 2. Design part
2.1 Justification of the production method
It is either impossible to produce many parts of modern machines, apparatus and devices by mechanical processing, or it is very time-consuming and expensive. Foundry comes to the rescue. A cast part can be produced by various methods: sand casting, chill casting, shell casting, lost wax casting. The choice of casting method is determined by the nature of the production of the part: individual, serial, mass. The most appropriate method of all the above methods for manufacturing a part is lost wax casting, since only with this casting method is it possible to obtain a part: made of heat-resistant alloy with a directional (monocrystalline) structure; with high surface cleanliness and precision. The industrial application of this method ensures the production from any casting alloys of complex-shaped castings weighing from several grams to tens of kilograms, with walls whose thickness in some cases is less than 1 mm, with a roughness from Rz = 20 μm to Ra = 1.25 μm ( GOST 2789 -73) and increased dimensional accuracy (up to 9 -10th qualification). Due to the chemical inertness and high fire resistance of mold shells, suitable for heating to temperatures exceeding the melting point of the poured alloy, it is possible to effectively use directional crystallization methods and control the solidification process to obtain hermetic, durable thin-walled precision castings, or single-crystal parts with high performance properties. The indicated capabilities of the method make it possible to bring the castings as close as possible to the finished part, and in some cases to obtain a finished part, the additional processing of which is not required. As a result, the labor intensity and cost of manufacturing products are sharply reduced, the consumption of metal and tools is reduced, energy resources are saved, and the need for highly qualified workers, equipment, fixtures, and production space is reduced. Lost wax castings are made from almost all foundry alloys: carbon and alloy steels, corrosion-resistant, heat-resistant and heat-resistant steels and alloys, cast iron, non-ferrous alloys, etc. Due to the fact that the “Matrix” is made of ZhS6U alloy and has large dimensions, the only rational way to manufacture it today is investment casting. 2.2 Analysis of manufacturability of part design
Manufacturability of a casting is understood as compliance of its design with the requirements of foundry production. Lost wax casting is a method of making castings by filling one-time molds with molten metal, obtained from one-time lost-wax (dissolved, burnt-out) models and subjected to calcination at high temperatures before pouring. The development of a technological process for manufacturing a casting begins with an analysis of the manufacturability of the part design. A technologically advanced part design is one that allows the production of a casting that meets the requirements for accuracy, surface roughness and physical and mechanical properties of the metal and quality at the lowest production costs. The manufacturability assessment is as follows: ) checking the wall thickness of the casting in all sections; ) checking the uniformity of the cross-section in various places of the structure; ) analysis of casting configuration. The wall thickness is checked to determine whether the part can be produced by investment casting. The smallest casting wall thickness that can be made in a casting is 0.5...0.7 mm. In the “Matrix” casting under consideration, the wall thickness is 70 mm, which is an acceptable thickness. According to this indicator, the part is technologically advanced. The reason for making a casting using the lost wax casting method is its serial production, reducing the labor intensity and cost of manufacturing the product. 2.3 Development of technology for producing LPVM castings
Figure 2.1 - General flow diagram of the technological process 2.3.1 Design of the drawing “Elements of a casting mold”
The drawing is prepared in accordance with GOST 31125-88 "Rules for graphic execution of mold elements and alloys .
According to these rules, the drawing of the mold elements is performed on a workpiece card or on a copy of the part drawing. The inscription "Elements of a casting mold" is placed above the main inscription of the drawing. The gating system is depicted on the scale of the drawing with a complex thin line. If the location is close and it is necessary to depict the gating system to scale, then it is allowed to depict it without taking into account the scale. Allowances for machining are depicted with a solid thin line. We apply allowances to the thinnest surfaces to strengthen the casting. Casting accuracy is regulated by GOST 26645-88. The amount of allowance for machining is set on the basis of this GOST, depending on the tolerance and dimensions of the casting for processing each element. The accuracy class of castings for dimensions and allowance depends on the method of casting the casting (5-6-5-4 GOST 26645-85). We assign allowances only to those surfaces that are subsequently subjected to mechanical processing. 2.3.2 Selecting the type and calculating the gating-feeding system
The gating-feeding system (GFS) serves to ensure the filling of the casting mold with metal at an optimal speed, excluding the formation of underfills and non-metallic inclusions in the casting, and to compensate for volumetric shrinkage during the period of solidification of the casting to obtain metal of a given density in it. LPS must also meet the requirements for manufacturability in the manufacture of models, molds and castings. It is necessary to strive to reduce LPS, since their excessive development leads to excessive consumption of metal, overestimation of labor costs, and low efficiency of use of equipment and space. When choosing a LPS design, it is necessary to strive to comply with the following fundamental provisions aimed at obtaining suitable castings and the cost-effectiveness of their production: ) ensure the principle of directional solidification, i.e. sequential solidification from the thinnest parts of the casting through its massive units to the profit, which should harden last; ) the longest walls and thin edges should be oriented vertically in the form, i.e. most favorable for their quiet and reliable filling; ) create conditions for economical and mechanized production of castings, including: unification of types of sizes of casting materials and their elements, taking into account the effective use of tooling, existing technological equipment, furnaces; the possibility of using model blocks and molds with metal frames; ease of execution and minimal amount of machining when cutting off castings and subsequent manufacturing of parts from them. According to the classification, there are seven types of LPS: with a central riser, with a horizontal collector, with a vertical collector and others. For the part under study, we select a type VI system (upper profit). This profit represents a reservoir of metal above the main thermal unit of the casting, obtained in a single mold. Metal is poured into the profit from a ladle. The concentration of the hottest melt in the upper part of the profit leads to the creation of a temperature gradient in the mold that is most favorable for feeding the casting. Due to this, distinguished by its high feeding capacity, the upper profit reliably ensures the production of dense metal from large, highly loaded cast parts. In the drawing, we draw the gating system with a solid thin line. The sections of the elements of the gating system are placed on the drawing field; they are not hatched. For each section of gating system elements, it is allowed to indicate the cross-sectional area in square centimeters, the number of sections and their total area. 2.3.3 Calculation of batteries using the inscribed sphere method
The diameter of the sphere inscribed in the upper node is determined from the casting drawing. To ensure complete filling of the mold, the largest diameter of the sphere is selected and is: at = 70mm. The profit margin is calculated using the following formulas: § Thickness (diameter): w = (1.1,2) xD at = (1.1.2) x70=70.84mm Let's take a w =70mm. § Width: w =a w =70mm. § Height: w = (0.2.0.5) xD at = (0.2.0.5) x70=14.35mm Let's take h w =20mm. § Bottom base thickness: P =k 1xD at =1.55x70=108mm, where k 1=1.55 - coefficient reflecting the nature and magnitude of alloy shrinkage. § Bottom base width: P =a P =108mm; § Cone apex angle: a =10.15° .
§ Profit Height: ¢ n = (2.5.3) xD at = (2.5.3) x70=175.210mm. We accept h ¢ n = 180mm. § Profit range: d =k 3xD U =2.5x70=175mm, where k 3=2.5 - coefficient reflecting the nature and amount of shrinkage of the alloy. 2.3.4 Development of a casting drawing
The casting drawing is made on the basis of the drawing of the casting mold elements. It contains technical requirements and all data necessary for the manufacture, inspection and acceptance of the casting. When drawing a casting, all allowances and tolerances are taken into account, indicating their values, in accordance with GOST 26645-88. Allowances are assigned for machining and shrinkage of the alloy. The internal contour of the processed surfaces, as well as holes, depressions and recesses that are not made in casting, is drawn with a solid thin line. Remains of feeders, vents, washers, risers and profits, if they are not completely removed in the foundry, are drawn with a thin line. When cutting with a cutter, disk cutter, saw, etc. The cutting line is made with a continuous thin line; during fire cutting - a solid wavy line. 2.3.5 Model mold design
A mold is a mold for making lost wax models. They must meet the following basic requirements: ensure the production of models with the specified accuracy and surface cleanliness; have a minimum number of connectors while ensuring convenient and quick removal of models; have devices for removing air from working cavities; be technologically advanced in production, durable and easy to use. For serial and mass production of castings, it is recommended to make molds according to the standard, from metal low-melting alloys. In such molds, up to several thousand models can be produced with satisfactory accuracy. The mold is designed based on the casting drawing, which is compiled from the part drawing. The drawing indicates the mold parting plane, processing allowances, base surface, metal supply location, dimensions of the gating system elements (usually feeders), and technical requirements for the casting. There is not yet a method for calculating the cavity of molds that would guarantee the production of castings with dimensions corresponding to the drawing. Depending on the technology adopted, the shrinkage of the model composition and metal varies, and the expansion of the shell shape changes. The change in these values depends on the model composition, the material of the mold, the method of compacting the filler, the type and temperature of the metal being poured, as well as on the geometric shape of the part itself and its location in the casting block. The form-forming surfaces of molds produced on metal-cutting machines must be polished. The mating surfaces of the molds (butts), the surface of pins, bushings, pads and other moving parts should be made with a roughness of Ra = 0.8-0.4 microns; surfaces forming the gating system, with Ra = 1.6-0.8 µm; the remaining non-working parts of the molds can be made with Rz = 40-10 microns. For the “Matrix” part, a single-cavity aluminum mold with a vertical connector was designed. 2.3.6 Assessment of the economic feasibility of the developed technology
When designing a technological process, it is necessary to assess the economic feasibility, i.e. make a rough assessment of the developed technology based on the rational use of metal. It is known: the weight of the casting is 18 kg, the weight of the gating-feeding system is 40 kg, The weight of the part according to the drawing is 12 kg. Yield: where Qex is the weight of the casting, kg. m. - weight of liquid metal per casting: , ( 2.3.6.2)
where Ql. With. - weight of the gating-feeding system, kg. VG =18/ (18+ 40) *100% = 31%.
Workpiece utilization rate: , (2.3.6.3)
where Qdet -
weight of the part according to the drawing, kg. KIZ= 12/18 =
0,66.
Metal utilization rate: , (2.3.6.4)
where Qн. R. - rate of metal consumption per part (casting): , (2.3.6.5)
where gop is the mass of irretrievable losses and unused waste, kg: n. R.= 20;
KIM = 18/20 =0,9
The result was: the yield was 31%, the workpiece utilization factor was 0.66, and the metal utilization factor was 0.9. Based on the obtained values, we can conclude that the developed technological process is economically feasible based on the rational use of metal. 3. Matrix casting manufacturing technology
3.1 Model manufacturing technology
3.1.1 Preparation of starting materials
In the conditions of this production, for the manufacture of models, a model composition is used, the starting materials of which are: grade A granulated carbide GOST 2081 (hereinafter referred to as urea), model composition ZGV - 101, regenerated model mass (hereinafter referred to as regenerate). The properties of the model composition are subject to a set of requirements that depend on the configuration, size and purpose of the casting, the required dimensional accuracy, type of production, the adopted technological option for the process of manufacturing mold shells, requirements for the level of mechanization and economic indicators of production. The properties of this model composition sufficiently ensure the production of high-quality models with simultaneous manufacturability of the composition (ease of preparation, ease of use, possibility of disposal). Preparation of urea. Urea crushing. Pour the urea from the bag into the chest, then crush it with a hammer into pieces no larger than 20 ´ 20´ 20mm. Grinding of urea. Pour the urea into the VM-50 vibrating mill with a scoop. Open the cooling valve of the vibration mill, press the “on” button. and grind for 30-50 minutes. At the end of the process, press the “stop” button and close the cooling valve of the vibrating mill. Drying urea. Pour urea into the container with a scoop, the height of the bulk layer is no more than 15 cm. Place the container with urea in a drying cabinet and dry it at a temperature of 60 - 80 ° From 2 hours, no less, with exhaust ventilation and air recirculation turned on. The drying mode is controlled using a potentiometer KSPZ GOST7164, operating in automatic mode. The urea is naturally cooled to room temperature. Containers with dried urea are stored in a drying cabinet. Sieving of urea. The urea is loaded into the runners with a scoop and crushed for 10 - 15 minutes. Place a container under the groove of the vibrating sieve, then load the crushed urea with a scoop into the sieve and turn it on by pressing the “Start” button. After sifting the urea, press the “Stop” button of the vibrating machine. The sifted urea is poured into a container and placed in a drying cabinet. Grinding and sifting of urea is carried out immediately before the process of preparing the model mass. Preparation of the model composition of ZGV - 101. Turn on the heating of the oven by opening the steam supply valve. The steam pressure according to the pressure gauge should be 0.1 mPa (1 kgf/cm 2). Load the model composition into the oven, maximum load 40 kg or no more than 3/4 of the volume of the oven bath. Then the model composition is brought to complete melting, stirring occasionally with a spatula. When complete melting of the model composition is achieved, its temperature is measured with a thermometer. Temperature should be 80 - 100 ° C. At the end of the process, the steam pressure is reduced to 0.04 - 0.05 mPa (0.4 - 0.5 kgf/cm 2), closing the steam valve. Notes: The preparation of the model regenerate is carried out in the same way, the model composition ZGV - 101 and the regenerate are prepared in different ovens, unused molten model composition may be stored in an oven at a steam pressure of no more than 0.05 mPa (0.5 kgf/cm 2),
It is allowed, if necessary, to prepare the model composition of ZGV - 101 with the addition of 1 %(by weight of the composition) triethanolamine at a temperature of 90 - 100 ° With thorough mixing for 10 - 15 minutes. 3.1.2 Preparation of model mass MV
Preliminary preparation of the model composition consists of alternately melting the components and then submitting them to the operation of preparing a paste-like composition. To obtain this casting, the most appropriate are model compositions of the 1st group. Model compositions of other groups have a number of disadvantages: they have a high drop point, wettability by suspension and a high expansion coefficient when heated, high viscosity, etc. We will use the model mass ZGV-101, as it most fully meets the requirements. Models made from model mass ZGV-101 are durable, heat-resistant, precise, with a hard and clean surface; when stored in a dry place, they retain surface quality and dimensional accuracy well. To prepare the model mass of MV, the model composition ZGV - 101 and urea are used. The ratio of the model composition of ZGV is 101 and urea 1: 1 by weight. for elements of the gating system, the MV model mass is prepared from model regenerate, The model mass from ZGV-101 and from the model regenerate is prepared in different thermostats. Sequence of the process. Turn on the thermostat with glycerin heating. The index of the potentiometer KSP - 3 is set to a temperature of 75 - 80 ° C. The melt of the model composition is stirred in the furnace with a spatula to ensure the complete disappearance of unmelted pieces and sediment. Place the bucket at the toe of the stove, tilt the stove by turning the lever and fill it with the model composition. Then the bucket with its contents is weighed and the result is recorded on a piece of paper. Pour the melt into the thermostat, avoiding spillage, and weigh the empty bucket, also recording the result. The amount of model composition is calculated. If necessary (if the amount of model composition poured into the thermostat is not enough), repeat the operation. The recommended amount of model composition poured into the thermostat is 8-12 kg, but not more than 14 kg. Measure the temperature of the model composition with a thermometer. The melt temperature before loading urea should be 75 - 85 ° WITH. Urea is loaded into a pre-weighed empty bucket with a scoop. Weigh the bucket with urea and load the measured amount with a scoop into the thermostat bath in 2 or 3 steps, mixing the mass with a spatula after each load. Place the stirrer over the thermostat bath and lower it by pressing the “Down” button until the blades are completely submerged. Close the thermostat with a lid and turn on the stirrer. Stir the mixture over its entire height until a homogeneous mass is obtained. Lumps of urea are not allowed in the finished model mass. Mixing time 20 - 30 minutes. Due to the high requirements for dimensional accuracy and surface quality of the casting, the quality of the starting materials is systematically monitored and the properties of the model composition are checked. They control strength, ductility, hardness, heat resistance, softening, melting, ignition, boiling points, viscosity, density, ash content, fluidity, volumetric and linear shrinkage, expansion when heated, surface quality of models or special samples. 3.1.3 Selection, calculation, characteristics of equipment and technology for preparing model mass
To prepare the model mass, we use the installation model PB 1646, the characteristics of which are given in Table 3.1 Table 3.1 - Technical characteristics of the installation model PB 1646: Parameters Highest productivity, l/h63 Highest pressure in the oil pipeline, MPa1 Temperature of the model mass at the outlet, ˚С70-80 Air content in the model mass, %0-20 Water temperature in the pumping-heating station, ˚С40-90 Steam pressure, MPa0.11-0.14 Steam temperature , ˚С100-110Consumption: steam, kg/h compressed air, m 3/h of water, m 3/h 25 0.5 1 Heater power, kW24 Installed power, kW34.1 Overall dimensions, mm: length width height 1100 900 1300 Weight, kg500 Рр=38324.24/ (1812*20) =1.06; R h = 1,06/2 = 0,53.
That. the required number of installations for preparing the model composition is 2. 3.1.4 Making a part model
The process of making models in molds includes preparing the mold, introducing the model composition into its cavity, holding the model until hardening, disassembling the mold and removing the model, as well as cooling the model to the temperature of the production room. Requirements for molds. Molds are allowed to be used if they have an issued passport with a conclusion on their suitability. Before starting work, check the condition of the mold; its working parts should not have nicks, deep marks or other defects that worsen the geometry and appearance of the model. The clamping devices must be in good working order. Residues of the model composition are not allowed on the forming surfaces and parting planes of the mold. Before work, lubricate the working cavities of the mold using a brush with a lubricant of the following composition: etheraldehyde fraction (hereinafter referred to as EAF) - 95 - 97%, castor oil - 3 - 5%. It is necessary to take into account that excessive lubrication deteriorates the quality of the surface of the models. The mold is assembled in strict sequence for this type. The clamps must be tightened tightly, using keys if necessary. The temperature of the mold has an important, often decisive influence on the quality of the models. Before starting work, molds are usually heated by introducing a model composition into them. In this case, the first (one or two) models are sent for remelting. The optimal temperature of the mold depends on the properties of the composition and shape of the models. For this model composition it is within 22 - 28º C. Fluctuations in the temperature of the mold cause a decrease in the dimensional accuracy of the models, and its low temperature increases the internal stresses in the models and leads to warping and cracking in them. During disassembly to remove models and assemble molds, they usually do not have time to cool to the optimal temperature. Therefore, forced cooling is used by immersing them in water or blowing them. Pressing in the model composition. Pressing of the MV model composition is carried out using pneumatic presses. The assembled mold is installed on the press table so that the filling hole is under the pneumatic press rod. Next, a glass is selected for pressing the model composition depending on the volume of the model, or according to the instructions in the detailed technology. The stroke of the rod should ensure that the mold is filled with a minimum remainder of the model composition (hereinafter referred to as press residue) in the glass. Lubricate the punch and glass with lubricant, place the glass on the plate, and load the model composition into it with a scoop from a thermostat or holding furnace. The temperature of the model composition is maintained within 60 - 85 ° C using the KSPZ potentiometer. During the work, the model composition is periodically mixed with a mechanical mass mixer. Place a glass with a portion of the model composition on the filling hole, insert a punch into the glass and press it. Pressure aging is done. Next, the pressure is removed, the glass is removed, the punch is pulled out and the press residue is removed. Pressing of the model mass is carried out using M31 pneumatic presses The required amount of equipment is calculated using the formula: Where Q- annual volume of work performed on this type of equipment, pcs.; Fd - actual annual equipment operating time, h; INR -
calculated productivity (10% less than the nameplate); RH- unevenness coefficient; for mass production: H
= 1 - 1,2; RR = ( 130933.7·1) / (2030·20) = 1.22; The intensity of equipment use relative to the actual time available is regulated by the load factor Rh,
it must be within Rh = 1,22/2 =0,61.
That. required number of presses: 2 pieces. Table 3.2 - Technical characteristics of the M31 pneumatic press Parameters Highest productivity: number of pressings per hour 250 Mass extrusion force, Pa (1-4) - 10 5Maximum pressing volume, l10 Mold compression force, kg1300 Outlet temperature of model composition, ˚С70 Installed power, kW1.5 Cylinder diameter, mm175 Piston stroke, mm150 Overall dimensions, mm: length width height 1010 590 1556 Weight, kg1750 3.1.5 Control of models and their finishing
Finishing of models and preparing them for assembly is carried out jointly by monitoring their quality. Models should be cleaned and their quality controlled only after they have been kept until completely cooled - at least 5 hours. Cracks, non-welds, non-fills, sink marks, warping and other gross defects are not allowed on the models. Burrs and flash on models are removed along the mold parting planes with a knife. Defects and roughness on the surfaces of the casting model are rubbed with a hot knife and a clean napkin, using the model composition: ceresin 50 - 80%, petroleum jelly 20 - 50%. An electric stove is used to heat the knives. On the model, it is allowed to repair single defects in the form of air bubbles, weight marks, scratches, small non-through cracks, etc. model composition KPTs - 1b, without violating the dimensions of the casting model. To remove crumbs, wipe the model with gauze or a napkin and blow with compressed air. 3.1.6 Assembling model blocks
Select the necessary elements of the gating system for assembling the block according to detailed technology. Models are assembled into blocks using a photo reference or sketch according to the instructions using a “spider”. Check the presence of cast part numbers (stamps). The casting serial number and alloy grade are written with a needle on the model, gating system (profit) and on the sample for chemical analysis. In the profit, air vents are made to remove air from the cavity of the model block during air-ammonia drying. To increase adhesion to the profitability of the frame model, a mesh is applied with a needle (the depth of the groove is approximately 1 mm, the mesh size is less than 30 ´ 30mm approximately). Assemble the block onto the “spider” using a soldering iron according to the sketch of the detailed technology, a control sample for assembling the block. If necessary, solder joints are coated with model composition KPTs-1b using a brush. Undercuts on blocks, cracks, cavities, gaps in soldering areas, smudges of the model composition and damage from a hot soldering iron are not allowed. When soldering a model, it is necessary to clean the soldering area, making smooth transitions from the feeder to the model. A sample is soldered to the gating system for chemical analysis, according to detailed technology. The material index is indicated on all elements of the gating system using a scriber. The assembled block is blown with compressed air and wiped with a dry cloth to remove crumbs from the surface. Next, a holding period is required to completely cool all parts of the model block to the temperature of the production room. The assembled unlined block is stored for no more than 7 days. 3.1.7 Block control
They check by external inspection the quality and correct assembly of the model block according to sketches and photo standards. A mandatory check also includes checking the quality of gluing of gating system elements to the model visually. Cracks, gaps, leaks, and sinkholes are not allowed here. Check the presence and correctness of material index markings on the part and on all elements of the gating system. 3.2 Ceramic shell manufacturing technology
A casting mold is a tool for processing molten metal in order to obtain castings with specified dimensions, surface roughness, structure and properties. The basis of the lost wax casting method is the shell: one-piece, hot, non-gas-forming, gas-permeable, rigid, with a smooth contact surface, precise. Two types of shells are known depending on the method of their manufacture: multilayer, obtained by applying a suspension followed by sprinkling and drying, and two-layer, obtained by electrophoresis. This technology uses a multilayer shell. The surface of the model block is moistened with the suspension by dipping and immediately sprinkled with granular material. The suspension adheres to its surface and accurately reproduces the configuration; the granular material is introduced into the layer of suspension, wetted by it, fixes the suspension on the surface of the block, creates the skeleton of the shell and thickens it. 3.2.1 Preparation of starting materials
3.2.1.1 Preparation of hydrolyzed ethyl silicate
Source materials: § Ethyl silicate 40 GOST 26376-80; § Solvent - ethyl alcohol (head fraction); § Hydrochloric acid - GOST 3118-77; § Distilled water; § Acetic acid. 1. Hydrolysis of ETS Hydrolysis -This is the process of replacing the ethoxyl groups contained in ethyl silicate (C 2N 5O) hydroxyl (OH) contained in water. Ethyl silicate is subjected to hydrolysis to give it the properties of a binder. Hydrolysis is accompanied by polycondensation (the combination of different or identical molecules into one with the formation of polymers and the release of the simplest substance) (C 2H 5O) 4+H 2O=Si(C 2H 5O) 3OH+C 2H 5OH Table 3.3 - Composition of hydrolyzed ETS -40
ETS -401 lGOST 26371 -74 EAF1.15 lOST 18 -121-80 N 2About 80 ml- HCl40 mlGOST 3118 -72
Hydrolysis of ethyl silicate to obtain binder solutions is carried out with an acidified solution of water in alcohol or acetone, since ethyl silicate and water dissolve well in them. To accelerate the hydrolysis reaction, acids are used, most often hydrochloric acid HCl. Typically, hydrolyzed ethyl silicate solution (ESS) contains 0.2 -0.3% HCl. Sequence of the process. Preparation of acidified water: a measured amount of acid is poured into distilled water and mixed. Add acidified solvent water in an amount » 10% of the total amount of solvent and mix thoroughly. Pour into hydrolyzer ½ part of ETS-40, turn on stirring and pour in ½ part of acidified water. The mixture is stirred for 8.10 minutes. Pour into hydrolyzer ½ part of the total amount of solvent intended for diluting ETS-40 and the remaining part of the original ETS-40. Stir for 2.3 minutes. Pour the remainder of the acidified water into the hydrolyzer, and stir the mixture for 8.15 minutes. The rest of the solvent is poured in, the mixture is stirred for 10.15 minutes. Turn off the hydrolyzer. Total hydrolysis time 35.40 minutes, hydrolysis temperature » 45 ° C. Pour the hydrolyzate into polished containers and cool to room temperature .
The shelf life of the hydrolyzate is no more than 3 days from the date of its manufacture. The hydrolyzate must provide the following indicators: 2 = 18¸ 22 %= 0,18¸ 0,24 %
Viscosity - 9,5¸ 11.5 centistokes. The viscosity of the hydrolyzate is checked before issuing for use. 3.2.1.2 Preparation of distensilimanite
The resulting distensilimanite is calcined in electrically heated chamber furnaces at 950 -1000 ° C for 3 hours. The height of the poured layer in the pan is 120 -130 mm. The calcined distensilimanite concentrate is sifted through a sieve. The calcination mode is recorded on the diagram. Distensilimanite is monitored for the content of unbound iron. Allowed content is from 0.09 to 1.0%.