SU1470423A1 - Method of investment-pattern casting - Google Patents

Abstract

The invention relates to the production of castings according to removable models. The purpose of the invention is to increase the productivity of castings due to the intensification of shell calcination operations, cooling castings and cleaning them from ceramics and increasing the hardness of metal castings and reducing the depth of metal decarburization of metal castings. After applying the suspension, the shell is sprinkled with a waste of the graphitization of electrode products (OPGEL) based on silicon and its dioxide with a content of 20 ... 40 wt.% Silicon carbide. The shell is also formed into a large fraction of OPGEL. The thermal conductivity of OPGEP is 0.7 ... 1.16 W / (m ^. K), the grain size for sprinkling the first layer of the form is 0.1 ... 0.315 mm, for the second and subsequent 0.315 ... 1.5 mm, and for support filler 6 ... 10 mm. Due to the high thermal conductivity, low bulk weight (630-800 kg / m ³ ) and black color, the calcination of the molds and the cooling of the metal are intensified. The creation in the form of a protective atmosphere reduces the decarburization of castings, and rapid cooling increases their hardness, OPGEL is formed by co-firing of quartz sand and coke at 2973 ... 3273 K for 10 ... 12 days. 4 tab.

Description

the main product of the graphitization process and increases the waste of castings in gas shells.

The thermal conductivity of the OPGEL used as the material of the cake and the supporting filler is O, 70 ... 1.16 W / (m K) and is provided with all components of the waste. OPGEP

less than 6 mm thick, reduces the gas permeability of the supporting filler, particles larger than 10.0 mm are not used, since they cannot provide a dense uniform gap;

The increase in labor productivity is achieved by reducing the cycle of the calcination of the shells and the intensification of

with a thermal conductivity of less than 0.7 W / (m K) of the cooling of castings, reduced, provides a high heating rate and cooling of the shells, and thermal conductivity of more than 1.16 W / (m-k) leads to the appearance of a defect in the castings underfilling. The waste of the graphitization process 5 of the electrode product is a mixture of sintered powder particles and black dust. The black color of the shell and the reference filler and the structure of the shell, created by the grain of the new composition at temperatures of calcining and pouring, contributes to the intensification of heat transfer.

The waste of the graphitization process, used as a dusting material, is well wetted by the bonding agent based on ethyl silicate and water glass. OPGEP is a porous material with a weight of kg / m.

The use of 0.1… O, 315 mm grains for the first layer 30 is due to the following: a grain size less than 0.1 mm does not provide sufficient strength for the cladding layer of the form due to the cracking of the shell: Pu dried. Grain particles of more than 0.315 mm reduce the quality of the surface of castings and their accuracy. The choice for the second and subsequent layers of the particle size of dusting material O, 315 ... 1.5 mm is associated with the condition of ensuring minimum porosity at the contact of the layers; particles larger than 1.5 mm increase the contact porosity, which leads to a decrease in the strength of the shape less than 0.315 mm do not provide reinforcement to the slurry layer, which leads to its destruction due to the formation of cracks. The particle size of the dusting material is 1.5-5.5 mm due to the requirements for the support layers of the form: particles less than 1.5 mm do not provide high heat resistance, particles more than 5.3 mm are not retained by the binder on the surface of the form .. JJ

The fractional composition of the reference, filler 6.0 ... 10, O mm provides high thermal conductivity and gas permeability. Use of particles

35

, 40

45

50

nor the duration of the operation of picking and cleaning castings from ceramics. The burden of calcination of shells on the basis of OPGEL in the reference opacifier OPGEP decreases from 4.0 to 1.0 ... 2.5 hours due to the rapid and uniform progress of the obolochkov forms

V.

OPGES as dusting and support filler significantly reduces the cooling time of castings after pouring, since at temperatures above 973 K radiant heat transfer plays a decisive role in heat transfer. The structure of the form-shell and supporting filler with pores that increase in size from the coated layers to the filler by choosing a rational grain composition of the dusting material provides for the creation of a directional and intense heat flux from the edges metal-form. High heat removal rate ensures fast metal crystallization. The metal practically does not penetrate into the pores of the shell, since the intensely cooling surface of the mold loses its fluidity. Castings obtained by the proposed method have high dimensional accuracy and a clean, non-stick surface. After the castings are cooled, the ceramics from 9 of their surface is removed on the embossed grating. Leaching is only necessary to remove ceramics from the holes. Since the final material and the reference filler, the OPGEP is calcined for a long time in the course of graphitization at temperatures significantly higher than the temperature / g of calcining and pouring the shell forms and the chemical composition is close to the composition of the hardened binder, there are no sintering processes, ceramics in cavities castings do not contain sparingly soluble in alkali compounds and are removed within 2 ... 3 hours.

cooling castings, reduce

nor the duration of the operation of the knockout and cleaning of castings from ceramics. The burden of calcination of shells on the basis of OPGEL in the reference opacifier OPGEP decreases from 4.0 to 1.0 ... 2.5 hours due to fast and uniform heating of the obolochkov forms

V.

OPGEP as dusting and support filler significantly reduces the cooling time of castings after pouring, since, at temperatures above 973 K, radiative heat transfer plays a decisive role in heat transfer. The structure of the form-shell and supporting filler with pores that increase in size from the coated layers to the filler by choosing a rational grain composition of the dusting material ensures the creation of a directional and intense heat flux from the metal-form interface. High heat removal rate ensures fast metal crystallization. The metal practically does not penetrate into the pores of the shell, since the intensely cooling surface of the mold loses its fluidity. Castings obtained by the proposed method have high dimensional accuracy and a clean, non-stick surface. After the castings are cooled, ceramics with 90% of their surface is removed on a knockout grid. Leaching is only necessary to remove ceramics from the holes. Since the conventional material and the reference filler (OPGEP) is calcined for a long time in the process of graphitization at temperatures much higher than the temperature / g of calcining and pouring the shell forms, and by chemical composition it is close to the composition of the hardened binder, sintering processes are absent, there are no ceramic in the cavity x castings do not contain sparingly soluble in alkali compounds and are removed within 2 ... 3 hours.

51470423

Due to intensive heat removal

The test results are given

From the casting with the shell and the supporting filler, a significant decrease or complete elimination of the decarbonized layer, grinding of the casting grain, which leads to an increase in hardness, wear resistance of the casting surface, and an increase in their service life, is achieved. In addition, heat-resistant materials and electricity are saved, as the length of the conveyors in the calcination and cooling zones is reduced.

The use of OPGEP provides recycling of graphitization process waste, the number of which reaches 100,000 tons annually.

The method is carried out as follows.

On the model. Castings of a complex configuration, the coating layer was applied successively using ethyl silicate suspension of the following composition,%: Ethyl silicate-40 9.85 Ethyl alcohol 9.79 Solvent acid 0.29 Water 1.96

The viscosity of the suspension for the first layer according to VZ-4, for the second, third and fourth 60. Drying each layer for 3 hours, t 20–22 ° C and humidity 70–80%. The chemical and fractional compositions of obshochnogo material are given in table. one.

After removal - shell models are molded with vibration into the filler.

The composition of the filler is given in table. 2

The heating rate of the molds during calcination and the cooling rate of the castings are determined using a set of chromel-aluminum thermocouples connected to a KSP-4 instrument with automatic recording.

Simultaneously with the mold shells, standard samples are made for strength testing, gas permeability table. 3

The duration of the casting, cooling and cleaning of the castings from ceramics, as well as the quality of the castings, depending on the method of their manufacture, are determined by standard, 10-d methods and are given in Table. four.

The method allows to reduce the process of making castings with one

15 applauded to improve the quality of pouring. The cost of castings is reduced due to the use of the base material and the reference filler of a cheaper material - process waste.

20 graphitization of electrode products.

At the same time, the waste disposal problem is solved.

Formula, and. acquisitions

25

A method of manufacturing castings on removable models, including the manufacture of shell molds by layering a slurry, sprinkling each layer with a heat-conducting material, calcining and pouring into the supporting filler, characterized in that, in order to increase the productivity of casting manufacturing due to the intensification of operations calcining the shells, cooling the buildings of castings and cleaning them out of ceramics and increasing the hardness of the metal of the castings and reducing the depth of the bezugle40 birth of the metal of the castings as dusting material of the base and the reference filler use the waste of the process of graphitization of electrode products based on silicon and its dioxide with

45 with a content of 20 ... 40 wt.% Silicon carbide, while the waste has a thermal conductivity of about, 70 ... 1.16 W / (m K) and grain sizes for the first layer to be 0.1 ... .. 0.315 mm, for the second

JJJin Irl W.H Dt 1 CiXlJTlTl .Chi l --J “. .- y- -,

cements and heat resistance in limestone and subsequent layers O, 315 ... 1.5 mm,

---. x 4 4-nrvtfr rT / TTU L T OrfCin -.- l () N

nym methods.

and for the reference filler 6 ... 10 m

The test results are given

in tab. 3

The duration of the operations of calcining, cooling and cleaning the castings from ceramics, as well as the quality of the castings produced, depending on the method of their manufacture, are determined by standard methods and are given in Table. four.

The method allows to reduce the process of making castings with one-.

Increased quality pouring. The cost of castings is reduced due to the use of cheaper material as core material and reference filler - process waste

graphitization of electrode products.

At the same time, the waste disposal problem is solved.

Formula, and. acquisitions

A method of manufacturing castings on removable models, including the manufacture of shell molds by layering a suspension, coating each layer with a heat-conducting material, calcining and pouring into a supporting filler, characterized in that, in order to improve the performance of the manufacture of castings due to the intensification of calcination operations shells, cooling of buildings of castings and their cleaning from ceramics and increasing the hardness of metal of castings and reducing the depth of decarburization of metal of castings, as a dusting material and filler used and the reference exhaust electrode graphitization process products based on silicon dioxide and

content of 20 ... 40 wt.% silicon carbide, while the waste has a thermal conductivity of about, 70 ... 1.16 W / (m K) and grain sizes for the first coating layer 0.1 .. ..0.315 mm for the second

J ". .- y- -,

and subsequent layers Oh, 315 ... 1.5 mm,

and subsequent layers Oh, 315 ... 1.5 mm,

---. x 4 4-nrvtfr rT / TTU L T OrfCin -.- l () N

and for the reference filler 6 ... 10 mm.

Waste of the graphite process- 20 of the electrode products

five

four

fations

That 19

80

0.70 0.315 0.315 0.315

Table color

10 3

T a l c a 3

Claims (1)

Claim A method of manufacturing castings according to removable models, including the manufacture of a shell mold by layer-by-layer application of a suspension, sprinkling of each layer with heat-conducting material, calcining and pouring in a support filler, characterized in that, in order to increase the productivity of manufacturing castings by intensifying the operations of calcining the shells, cooling the castings and their cleaning from ceramics and increasing the hardness of metal castings and reducing the depth of decarburization of metal castings, as a coating material and op The filler uses waste from the graphitization process of electrode products based on silicon and its dioxide with a content of 20 ... 40 wt.% silicon carbide, while the waste has a thermal conductivity of 0.70 ... 1.16 W / (mK) and dimensions grains for the first coating layer 0.1 ... 0.315 mm, for the second and subsequent layers 0.315 ... 1.5 mm, and for the support filler 6 ... 10 mm. Table 1 Shell manufacturing option Layer Material ----------- _; --------------- (full composition of the total, wt.% ' Thermal conductivity of bulk material Fractional composition by layers, mm silicon carbide silicon and its dioxide Waste of the graphitization process - 20 electrode products 80 0.70 0.315 0.315 0.315 I Table 2 Manufacturing option - ¹ dalia otlmzok Material of support filler _w Grain size of a naughty filler, mm 1 Nenovamot b 2 Waste of grafatacni process; 8 3 Well 10 4 s Table 3 Variant of prepared shells Accuracy, MPa, reg, K at a pace * Gas-permeable BONE ’after proc * Diva * NIN Heat resistance. from · 273 1173 »Deformation 1 4.7 6.1 1.5 6.2 2 5.1 6.7. 1.7 7.4 3 5.3 6.9 1.6 7.5 4 5.3 6.7 1.5 7.3 Table 4 Production Option from * lmvokh The speed of heating the shells, K / min Calcination duration,. h Duration of cooling castings, I The area. ceramic coated castings, X after knocking out   after 2 culprit bottom of the Garde cue * wife post from * nivka to * mn heat treatment * work a 1 16 2.5 5.8 12 0 0.25 42 2 18 2.3 5.6 10 0 0.20 42 3 19 1.4 . 5,4 10 0 0.16 45 4 20 1.4 5.2 10 0 0.1 48