CN114433818A - Low-pressure casting method and device for thin-wall complex aluminum alloy gearbox shell - Google Patents
Low-pressure casting method and device for thin-wall complex aluminum alloy gearbox shell Download PDFInfo
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- 238000005266 casting Methods 0.000 title claims abstract description 123
- 238000000034 method Methods 0.000 title claims abstract description 37
- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 23
- 238000001816 cooling Methods 0.000 claims abstract description 20
- 238000007711 solidification Methods 0.000 claims abstract description 10
- 230000008023 solidification Effects 0.000 claims abstract description 10
- 239000000956 alloy Substances 0.000 claims description 50
- 229910045601 alloy Inorganic materials 0.000 claims description 49
- 239000011550 stock solution Substances 0.000 claims description 38
- 239000002994 raw material Substances 0.000 claims description 36
- 238000002844 melting Methods 0.000 claims description 24
- 230000008018 melting Effects 0.000 claims description 24
- 238000007670 refining Methods 0.000 claims description 18
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 12
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 12
- 238000007872 degassing Methods 0.000 claims description 12
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- 239000007788 liquid Substances 0.000 claims description 9
- 239000007789 gas Substances 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 7
- 229910052786 argon Inorganic materials 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 6
- 238000005429 filling process Methods 0.000 claims description 6
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 239000011162 core material Substances 0.000 description 50
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D18/00—Pressure casting; Vacuum casting
- B22D18/04—Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
- B22D15/02—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor of cylinders, pistons, bearing shells or like thin-walled objects
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D18/00—Pressure casting; Vacuum casting
- B22D18/08—Controlling, supervising, e.g. for safety reasons
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Abstract
The invention discloses a low-pressure casting method and a low-pressure casting device for a thin-wall complex aluminum alloy gearbox shell, which belong to the technical field of automobile accessory manufacturing, and comprise a dead head, a sand core, a pouring gate and a loose core, wherein the sand core is provided with a cylindrical feeding channel, the pouring gate is provided with an inner runner, the pouring gate and the sand core are connected through the matching of the cylindrical feeding channel and the inner runner, the inner runner is communicated with a bolt column of a casting, the loose core is arranged at the outer side of the pouring gate and the sand core, the loose core is connected with an external pushing hydraulic cylinder, and an upper die, the invention adopts the sand core with an internal runner, the loose core is partially heated, the local part is cooled by a cooling pin, and the boss of the flange bolt adopts a comprehensive means of riser feeding, thereby realizing the sequential solidification of the casting in the low-pressure casting process, and solving the problems of great difference of the wall thickness of the casting, complex structure, poor forming and shrinkage porosity of the product.
Description
Technical Field
The invention relates to a casting method and a casting device, in particular to a low-pressure casting method and a low-pressure casting device for a thin-wall complex aluminum alloy gearbox shell, and belongs to the technical field of automobile part manufacturing.
Background
The existing transmission case matched with the car engine is relatively simple in structure because of low load and small size and is mainly produced by aluminum alloy high-pressure casting; the rear shell of the automatic gearbox for the heavy truck has large size and high load, and can meet the requirements only by using alloy materials with higher mechanical strength and heat treatment strengthening, and the rear shell of the automatic gearbox for the heavy truck has large size and thin wall: the product has the external dimension of 562 by 451 by 308mm, the wall thickness of the total side wall is 5.5mm, the product has a complex structure, the local wall thickness is not uniform, the casting has thermal junctions with the wall thickness of 38-59mm at different positions, and the shrinkage defect is easily formed.
The invention provides a casting mold and a casting process of a gearbox casing in the patent with the application number of CN109175306A, a casting system of a gravity casting mold is welded on the basis of the original mold, a pouring channel water inlet communicated with a casting cavity is arranged on a lower mold, the casting mold is improved to be provided with a connecting part of a low-pressure casting machine, and the improved low-pressure casting mode can effectively solve the problem that products are leaked and scrapped due to shrinkage porosity and shrinkage cracks at the transition position of rapid thickness change of the gearbox casing wall in the casting process.
The invention provides a casting method of a rear shell of a gearbox, which is disclosed in the patent with the application number of CN110449556A, and aims at a part with concentrated heat collection of a casting (a chiller is arranged at the joint of a reinforcing rib and a boss on the side surface of the casting) to design a chiller for chilling, so that the casting is sequentially solidified, casting defects are reduced, the problems that a heat joint is easily formed at the joint of the reinforcing rib and the boss on the casting, the casting is not easily sequentially solidified, and the casting has casting defects are effectively solved, and under the action of the chiller, the positions of the casting defects are sequentially solidified to form a compact structure, crystal grains at the position are refined, and the mechanical performance of the casting is improved.
The two patents of the invention both improve the forming method of the casting, but the part with thick wall thickness of the product has a plurality of shrinkage porosity defects, because the product has a complex structure and the wall thicknesses at different positions are greatly different, a common pouring system is adopted, the normal sequential solidification cannot be ensured, and the position with large wall thickness can generate thermal junctions to generate the shrinkage porosity defects.
The flange bolt boss of the gearbox shell has the defect of shrinkage porosity, if the pouring gate is arranged on the end face of a bearing hole of the gearbox shell, the flange bolt boss is located at the topmost end of the casting, and due to the fact that the thickness of the flange bolt boss is about 28mm, and the thickness of the connecting wall below the flange bolt boss is 5.5mm, simulation shows that a simple pouring system cannot be formed and solidified from top to bottom sequentially, and a thermal section is easily generated at the thick part of the flange bolt boss. In addition, the height of the gearbox shell is 308mm, the shrinkage defect of a flange bolt boss is difficult to solve by arranging an inner runner at the sprue,
bosses with the height of about 32-36mm are arranged in 4 reaction pin holes in the inner cavity of the gearbox shell, simulation shows that a thermal node is easy to generate in the gearbox shell to form a shrinkage porosity defect,
the bolt column has the shrinkage porosity defect, the wall thickness of the connection wall between the bolt column and the bearing hole of the gearbox shell is 5.5mm, simulation shows that the 5.5mm thin wall position is easy to solidify in advance during solidification, the feeding of a sprue to the bolt column is blocked, a thermal node is formed in the bolt column to cause the shrinkage porosity defect,
the wall thickness of each part of the end surface of the gate of the transmission case is different from the center of the gate by 72-306mm, simulation shows that a simple gate cannot meet feeding effect, and a thermal node is easily formed at the part with large wall thickness, so that shrinkage porosity is caused.
Therefore, a low-pressure casting method and a low-pressure casting device for a thin-wall complex aluminum alloy gearbox shell are provided.
Disclosure of Invention
The invention aims to solve the problems and provide a low-pressure casting method and a low-pressure casting device for a thin-wall complex aluminum alloy gearbox shell.
The invention realizes the purpose through the following technical scheme, and the low-pressure casting device for the thin-wall complex aluminum alloy gearbox shell comprises a dead head, a sand core, a pouring gate and a loose core, wherein a cylindrical feeding channel is formed in the sand core, an inner runner is arranged on the pouring gate, the inner runner is distributed along the shape of the pouring gate, the pouring gate and the sand core are connected through the matching of the cylindrical feeding channel and the inner runner, and the inner runner is communicated with a bolt column of a casting.
The core pulling device comprises a pouring gate, a sand core, a core pulling head, a core pulling hydraulic cylinder, an upper die, a lower die, a core pulling mold, a pouring gate, a riser and the sand core, wherein the core pulling mold is arranged on the pouring gate and the outer side of the sand core, the core pulling hydraulic cylinder is connected with an external pushing hydraulic cylinder, and the upper die, the lower die, the core pulling mold, the pouring gate, the riser and the sand core jointly form a casting forming mold.
Preferably, the molding surface of the sand core is provided with a coating for demolding the casting, and the coating is specifically an alcohol-based coating of HA1135 in Shanghai Europe.
By adopting the scheme, the sand core with the surface sprayed with the paint is utilized to form the external shape of the gearbox shell, and the appearance is ensured to be consistent with the forming roughness of the metal mold.
Preferably, the outer wall of the sand core is in the shape-following wave pattern.
By adopting the above scheme, adopt the wave line of following the shape, reduced the weight of psammitolite, increased the heating area of system core in-process, can reduce the curing time of system core process, improve system core efficiency, also increased the carminative area of psammitolite in the casting process simultaneously, resin is heated and is outgassed in the reduction psammitolite material, immerses the risk of foundry goods.
Preferably, the sand core is provided with a cooling pin, the cooling pin is embedded in the upper die, and the cooling pin is a water-cooling pipe.
By adopting the scheme, the sand core with the built-in internal flow channel is utilized, the core-pulling part is heated, the local part is cooled by the cooling pin, and the boss of the flange bolt adopts a comprehensive means of riser feeding, so that the sequential solidification of the casting in the low-pressure casting process is comprehensively and thoroughly realized, and the problems of great difference of the wall thickness of the casting, complex structure, and easy generation of poor forming and shrinkage porosity defects of the product are solved.
A low-pressure casting method for a thin-wall complex aluminum alloy gearbox shell comprises the following steps:
1) assembling and preheating a casting device, namely assembling the upper die, the lower die, the core pulling and the sand core of the casting device, wherein the assembling is to fix the upper die and the lower die of a die on a 800 kg low-pressure casting machine, the core pulling is installed on a guide rail around the lower die, the upper die, the lower die and the core pulling of the die are preheated before casting, the preheating temperature of the upper die and the lower die of the die is not less than 350 ℃, and the core pulling temperature is not less than 250 ℃;
2) the method comprises the steps of raw material proportioning, melting and purifying, selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then drying an aluminum melting furnace, then putting the prepared alloy raw materials into the aluminum melting furnace for melting at 780-790 ℃, transferring the molten raw materials into a low-pressure heat-preserving furnace for refining, degassing and slagging after the raw materials are melted, degassing for 2 times by adopting high-purity argon gas for 15min each time, and refining to obtain an alloy stock solution;
3) injecting an alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a riser tube, conveying the alloy stock solution subjected to refining and impurity removal treatment into the mold through the riser tube, filling a mold cavity with the alloy stock solution from bottom to top under certain pressure, solidifying and forming under the pressure, performing the processes of liquid lifting, primary mold filling, secondary mold filling, pressurizing, pressure maintaining and pressure releasing in the mold cavity filling process, and refluxing the residual alloy solution in the riser tube into the low-pressure heat preservation furnace after pressure releasing.
Preferably, in step 3, feeding heads are arranged on flange bolt bosses of the gearbox shell to form a solidification sequence from bottom to top, and a hot spot at the thick part of the flange bolt boss is introduced into the feeding heads, so that the alloy stock solution is finally contracted in the feeding heads.
Preferably, in the step 3, bosses with the height of about 32-36mm are arranged in 4 reaction pin holes in the inner cavity of the gearbox shell, simulation shows that a thermal node is easily generated inside to form shrinkage porosity defects, and cooling pins are arranged above the 4 reaction pin holes in the inner cavity.
Preferably, in the step 3, the thickness of the connecting wall between the bolt column and the bearing hole of the gearbox shell is 5.5mm, simulation shows that the 5.5mm thin wall is easy to solidify in advance when the connecting wall is solidified, the feeding of the gate to the bolt column is blocked, a thermal link is formed in the bolt column, the shrinkage porosity defect is caused, the inner runner arranged at the gate is connected with the lower part of the bolt column for feeding, and the inner runner is arranged in the sand core.
Preferably, in step 3, the large wall thickness part at each position of the gate end surface of the transmission housing is far away from the center of the gate, simulation shows that a simple gate cannot meet the feeding effect, a thermal node is easily formed at the large wall thickness part to cause shrinkage porosity defect, and an inner runner is designed on the gate to enhance the feeding effect.
The beneficial effects of the invention are:
1. the invention utilizes the sand core with the surface sprayed with the paint to form the external shape of the gearbox shell, and ensures that the appearance is consistent with the forming roughness of the metal mold.
2. The bolt columns at different height positions of the gearbox shell are fed by the internal runner built in the sand core, and the local thermal junctions in the bolt columns are introduced into the internal runner, so that the problem of local shrinkage porosity of the bolt columns is solved, and meanwhile, the bolt columns are far away from the center of the pouring gate, so that the internal runner is designed and connected between the center of the pouring gate and the internal runner built in the sand core to ensure the feeding effect of the internal runner built in the sand core. The connecting inner runner is mainly formed by lower die metal instead of sand cores, the sand cores are light and thin, on one hand, the solidification time in the core making process is reduced, the core making efficiency is improved, on the other hand, the gas forming amount of the sand cores is also reduced, and the risk that gas enters the casting to generate pinholes and air holes is reduced. In addition, the inner runner designed on the sprue solves the problem of shrinkage porosity of large wall thickness parts at each position of the end surface of the sprue of the casting.
3. The sand core adopts the conformal raised grains outside the sand core, so that the weight of the sand core is reduced, the heating area in the core making process is increased, the curing time in the core making process can be reduced, the core making efficiency is improved, the exhaust area of the sand core in the casting process is increased, and the risk that resin in a sand core material is heated, outgas and is immersed into a casting is reduced.
4. The invention comprehensively adopts the sand core with the built-in inner runner, the core-pulling part is heated, the local part is cooled by the cooling pin, and the flange bolt boss adopts the comprehensive means of riser feeding, thereby comprehensively and thoroughly realizing the sequential solidification of the casting in the low-pressure casting process, and solving the problems of great difference of the wall thickness of the casting, complex structure, and easy generation of poor forming and shrinkage porosity defects of the product.
Drawings
FIG. 1 is a schematic view of a casting apparatus according to the present invention.
FIG. 2 is a schematic bottom view of the casting apparatus of the present invention.
Fig. 3 is a schematic view of the structure of the sand core and the gate in the present invention.
Fig. 4 is a schematic view showing the entire construction of the casting apparatus of the present invention.
FIG. 5 is a schematic view of a gate structure according to the present invention.
FIG. 6 is an X-ray inspection of the finished casting of the present invention.
In the figure: 1. the casting device comprises a riser, 2 parts of a sand core, 2-1 parts of a coating, 2-2 parts of a conformal raised grain, 3 parts of a sprue, 3-1 parts of an inner runner, 4 parts of a cooling pin, 5 parts of a casting, 5-1 parts of a bolt column, 6 parts of a loose core, 6-1 parts of a heating pipe, 7 parts of a cylindrical feeding channel.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Please refer to fig. 1-6.
Example 1
A low-pressure casting device for a thin-wall complex aluminum alloy gearbox shell comprises a riser 1, a sand core 2, a pouring gate 3 and a loose core 6, wherein a cylindrical feeding channel 7 is formed in the sand core 2, an inner runner 3-1 is arranged on the pouring gate 3, the inner runner 3-1 is distributed along the shape of the pouring gate 3, the problem of shrinkage porosity of large wall thickness parts at each position of the end face of the pouring gate of a casting is solved through the inner runner designed on the pouring gate 3, the pouring gate 3 and the sand core 2 are connected through the cylindrical feeding channel 7 and the inner runner 3-1 in a matched mode, and the inner runner 3-1 is communicated with a bolt column 5-1 of the casting 5.
The core pulling 6 is arranged at the outer side of the pouring gate 3 and the sand core 2, the core pulling 6 is connected with an external pushing hydraulic cylinder, and the upper die, the lower die, the core pulling 6, the pouring gate 3, the riser 1 and the sand core 2 jointly form a forming die of the casting 5 (the upper die and the lower die are both basic dies in the existing casting device and are not shown in the figure).
As a technical optimization scheme of the invention, as shown in figure 3, a coating 2-1 for demoulding a casting 5 is arranged on the forming surface of the sand core 2, and the coating 2-1 is specifically an alcohol-based coating of HA1135 in Shanghai European district.
When the invention is practically used, the sand core 2 with the surface sprayed with the paint 2-1 is used for forming the external shape of the gearbox shell, and the appearance is ensured to be consistent with the roughness formed by a metal mold.
As a technical optimization scheme of the invention, as shown in figure 2, the outer wall of the sand core 2 adopts conformal raised grains 2-2.
When the invention is practically used, the conformal raised grains 2-2 are adopted, the weight of the sand core 2 is reduced, the heating area in the core making process is increased, the curing time in the core making process can be reduced, the core making efficiency is improved, meanwhile, the exhaust area of the sand core 2 in the casting process is increased, and the risk that resin in the material of the sand core 2 is heated, outgassed and immersed into a casting 5 is reduced.
As a technical optimization scheme of the invention, as shown in fig. 1 and 4, a cooling pin 4 is arranged on a sand core 2, the cooling pin 4 is inlaid in an upper die and is not arranged on the sand core, a casting is positioned at the bottom of the upper die and is positioned at the top of the sand core, the cooling pin 4 is specifically a water cooling pipe, and a heating pipe 6-1 is arranged in a core-pulling 6.
When the invention is practically used, the loose core 6 is partially heated, the local part is cooled by the cooling pin 4, and the flange bolt boss adopts a comprehensive means of feeding by the riser 1, so that the sequential solidification of the casting 5 in the low-pressure casting process is completely realized, and the problems of great wall thickness difference, complex structure, and easy generation of poor forming and shrinkage porosity defects of the casting 5 are solved.
A low-pressure casting method for a thin-wall complex aluminum alloy gearbox shell comprises the following steps:
1) assembling and preheating a casting device, namely assembling an upper die, a lower die, a core pulling 6 and a sand core 2 of the casting device, wherein the assembling is to fix the upper die and the lower die of the die on a 800 kg low-pressure casting machine, the core pulling 6 is installed on a guide rail around the lower die, the upper die, the lower die and the core pulling 6 of the die are preheated before casting, the preheating temperature of the upper die and the lower die of the die is not lower than 350 ℃, the core pulling temperature is not lower than 250 ℃, a riser 1, a sprue 3 and a casting 5 are all formed by matching alloy stock solution with the die and the sand core 2, and the casting 5 is formed under the matching of the upper die, the lower die, the core pulling 6, the sprue 3, the riser 1 and the sand core 2;
2) the method comprises the steps of raw material proportioning, melting and purifying, selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then drying an aluminum melting furnace, then putting the prepared alloy raw materials into the aluminum melting furnace for melting at 780-790 ℃, transferring the molten raw materials into a low-pressure heat-preserving furnace for refining, degassing and slagging after the raw materials are melted, degassing for 2 times by adopting high-purity argon gas for 15min each time, and refining to obtain an alloy stock solution;
3) injecting an alloy stock solution, connecting a low-pressure holding furnace containing the alloy stock solution with a mold through a liquid lifting pipe, conveying the alloy stock solution subjected to refining and impurity removal treatment into the mold through the liquid lifting pipe, filling a mold cavity with the alloy stock solution from bottom to top under certain pressure, solidifying and forming under the pressure, performing the processes of liquid lifting, primary mold filling, secondary mold filling, pressurizing, pressure maintaining and pressure relieving in the mold cavity filling process, and refluxing the residual alloy solution in the liquid lifting pipe into the low-pressure holding furnace after pressure relief;
example 2
A low-pressure casting method for a thin-wall complex aluminum alloy gearbox shell comprises the following steps:
1) assembling and preheating a casting device, namely assembling an upper die, a lower die, a core pulling 6 and a sand core 2 of the casting device, wherein the assembling is to fix the upper die and the lower die of the die on a 800 kg low-pressure casting machine, the core pulling 6 is installed on a guide rail around the lower die, the upper die, the lower die and the core pulling 6 of the die are preheated before casting, the preheating temperature of the upper die and the lower die of the die is not lower than 350 ℃, the core pulling temperature is not lower than 250 ℃, a riser 1, a sprue 3 and a casting 5 are all formed by matching alloy stock solution with the die and the sand core 2, and the casting 5 is formed under the matching of the upper die, the lower die, the core pulling 6, the sprue 3, the riser 1 and the sand core 2;
2) the method comprises the steps of raw material proportioning, melting and purifying, selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then drying an aluminum melting furnace, then putting the prepared alloy raw materials into the aluminum melting furnace for melting at 780-790 ℃, transferring the molten raw materials into a low-pressure heat-preserving furnace for refining, degassing and slagging after the raw materials are melted, degassing for 2 times by adopting high-purity argon gas for 15min each time, and refining to obtain an alloy stock solution;
3) injecting an alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a riser tube, conveying the alloy stock solution subjected to refining and impurity removal treatment into the mold through the riser tube, filling a mold cavity with the alloy stock solution from bottom to top under certain pressure, solidifying and forming under the pressure, performing a liquid lifting-primary filling-secondary filling-pressurizing-pressure maintaining-pressure releasing process in the mold cavity filling process, and refluxing the residual alloy solution in the riser tube into the low-pressure heat preservation furnace after pressure releasing;
as a technical optimization scheme of the invention, in step 3, feeding heads 1 are arranged on flange bolt bosses of a gearbox shell to form a solidification sequence from bottom to top, and a thermal node at the thick part of the flange bolt bosses is introduced into the feeding heads 1, so that alloy stock solution is finally contracted in the feeding heads 1.
Example 3
A low-pressure casting method for a thin-wall complex aluminum alloy gearbox shell comprises the following steps:
1) assembling and preheating a casting device, namely assembling an upper die, a lower die, a core pulling 6 and a sand core 2 of the casting device, wherein the assembling is to fix the upper die and the lower die of the die on a 800 kg low-pressure casting machine, the core pulling 6 is installed on a guide rail around the lower die, the upper die, the lower die and the core pulling 6 of the die are preheated before casting, the preheating temperature of the upper die and the lower die of the die is not lower than 350 ℃, the core pulling temperature is not lower than 250 ℃, a riser 1, a sprue 3 and a casting 5 are all formed by matching alloy stock solution with the die and the sand core 2, and the casting 5 is formed under the matching of the upper die, the lower die, the core pulling 6, the sprue 3, the riser 1 and the sand core 2;
2) the method comprises the steps of raw material proportioning, melting and purifying, selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then drying an aluminum melting furnace, then putting the prepared alloy raw materials into the aluminum melting furnace for melting at 780-790 ℃, transferring the molten raw materials into a low-pressure heat-preserving furnace for refining, degassing and slagging after the raw materials are melted, degassing for 2 times by adopting high-purity argon gas for 15min each time, and refining to obtain an alloy stock solution;
3) injecting an alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a riser tube, conveying the alloy stock solution subjected to refining and impurity removal treatment into the mold through the riser tube, filling a mold cavity with the alloy stock solution from bottom to top under certain pressure, solidifying and forming under the pressure, performing a liquid lifting-primary filling-secondary filling-pressurizing-pressure maintaining-pressure releasing process in the mold cavity filling process, and refluxing the residual alloy solution in the riser tube into the low-pressure heat preservation furnace after pressure releasing;
as a technical optimization scheme of the invention, in the step 3, bosses with the height of about 32-36mm are arranged in 4 reaction pin holes in the inner cavity of the gearbox shell, simulation shows that thermal junctions are easily generated in the inner part to form shrinkage porosity defects, and cooling pins 4 are arranged above the 4 reaction pin holes in the inner cavity.
Example 4
A low-pressure casting method for a thin-wall complex aluminum alloy gearbox shell comprises the following steps:
1) assembling and preheating a casting device, namely assembling an upper die, a lower die, a core pulling 6 and a sand core 2 of the casting device, wherein the assembling is to fix the upper die and the lower die of a die on a 800 kg low-pressure casting machine, the core pulling 6 is installed on a guide rail around the lower die, the upper die, the lower die and the core pulling 6 of the die are preheated before casting, the preheating temperature of the upper die and the lower die of the die is more than or equal to 350 ℃, the core pulling temperature is more than or equal to 250 ℃, a riser 1, a pouring gate 3 and a casting 5 are all formed by matching alloy stock solution with the die and the sand core 2, and the casting 5 is formed under the matching of the upper die, the lower die, the core pulling 6, the pouring gate 3, the riser 1 and the sand core 2;
2) the method comprises the steps of raw material proportioning, melting and purifying, selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then drying an aluminum melting furnace, then putting the prepared alloy raw materials into the aluminum melting furnace for melting at 780-790 ℃, transferring the molten raw materials into a low-pressure heat-preserving furnace for refining, degassing and slagging after the raw materials are melted, degassing for 2 times by adopting high-purity argon gas for 15min each time, and refining to obtain an alloy stock solution;
3) injecting an alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a riser tube, conveying the alloy stock solution subjected to refining and impurity removal treatment into the mold through the riser tube, filling a mold cavity with the alloy stock solution from bottom to top under certain pressure, solidifying and forming under the pressure, performing a liquid lifting-primary filling-secondary filling-pressurizing-pressure maintaining-pressure releasing process in the mold cavity filling process, and refluxing the residual alloy solution in the riser tube into the low-pressure heat preservation furnace after pressure releasing;
as a technical optimization scheme of the invention, in the step 3, the thickness of a connecting wall between a bolt column 5-1 of a gearbox shell and a bearing hole is 5.5mm, simulation shows that the 5.5mm thin wall is easy to solidify in advance when the connecting wall is solidified, the feeding of a sprue 3 to the bolt column 5-1 is blocked, a thermal node is formed in the bolt column 5-1 to cause shrinkage porosity defect, an inner runner 3-1 arranged at the sprue 3 is connected with the lower part of the bolt column 5-1 for feeding, and the inner runner 3-1 is arranged in a sand core 2.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (9)
1. The utility model provides a complicated aluminum alloy gearbox casing low pressure casting device of thin wall which characterized in that: the casting device comprises a riser (1), a sand core (2), a pouring gate (3) and a loose core (6), wherein a cylindrical feeding channel (7) is formed in the sand core (2), an inner runner (3-1) is arranged on the pouring gate (3), the inner runner (3-1) is distributed along the shape of the pouring gate (3), the pouring gate (3) and the sand core (2) are connected through the matching of the cylindrical feeding channel (7) and the inner runner (3-1), and the inner runner (3-1) is communicated with a bolt column (5-1) of a casting (5);
the core pulling die is characterized in that the core pulling head (6) is arranged on the pouring gate (3) and the outer side of the sand core (2), the core pulling head (6) is connected with an external pushing hydraulic cylinder, and an upper die, a lower die, the core pulling head (6), the pouring gate (3), the riser (1) and the sand core (2) jointly form a forming die of a casting (5).
2. The low-pressure casting device for the thin-wall complex aluminum alloy gearbox shell according to claim 1, characterized in that: and a coating (2-1) for demolding the casting (5) is arranged on the molding surface of the sand core (2), and the coating (2-1) is specifically an alcohol-based coating.
3. The low-pressure casting device for the thin-wall complex aluminum alloy gearbox shell according to claim 1, characterized in that: the outer wall of the sand core (2) adopts conformal raised grains (2-2).
4. The low-pressure casting device for the thin-wall complex aluminum alloy gearbox shell according to claim 1, characterized in that: the sand core (2) is provided with a cooling pin (4), the cooling pin (4) is embedded in the upper die, and the cooling pin (4) is specifically a water-cooling pipe.
5. The low-pressure casting device for the thin-wall complex aluminum alloy gearbox shell according to claim 1, characterized in that: a heating pipe (6-1) is arranged in the loose core (6).
6. The low-pressure casting method for the thin-wall complex aluminum alloy gearbox shell according to any one of claims 1 to 5, characterized by comprising the following steps of:
1) assembling and preheating a casting device, namely assembling the upper die, the lower die, the core pulling (6) and the sand core (2) of the casting device, wherein the assembling is to fix the upper die and the lower die of the die on a 800 kg low-pressure casting machine, the core pulling (6) is installed on a guide rail around the lower die, the upper die, the lower die and the core pulling (6) of the die are preheated before casting, the preheating temperature of the upper die and the lower die of the die is not less than 350 ℃, and the core pulling temperature is not less than 250 ℃;
2) the method comprises the steps of raw material proportioning, melting and purifying, selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then drying an aluminum melting furnace, then putting the prepared alloy raw materials into the aluminum melting furnace for melting at 780-790 ℃, transferring the molten raw materials into a low-pressure heat-preserving furnace for refining, degassing and slagging after the raw materials are melted, degassing for 2 times by adopting high-purity argon gas for 15min each time, and refining to obtain an alloy stock solution;
3) injecting an alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a riser tube, conveying the alloy stock solution subjected to refining and impurity removal treatment into the mold through the riser tube, filling a mold cavity with the alloy stock solution from bottom to top under certain pressure, solidifying and forming under the pressure, performing the processes of liquid lifting, primary mold filling, secondary mold filling, pressurizing, pressure maintaining and pressure releasing in the mold cavity filling process, and refluxing the residual alloy stock solution in the riser tube into the low-pressure heat preservation furnace after pressure releasing.
7. The low-pressure casting method for the thin-wall complex aluminum alloy gearbox shell according to claim 6, characterized by comprising the following steps of: in the step 3, feeding heads (1) are arranged on bosses of flange bolts of the gearbox shell to form a solidification sequence from bottom to top, and a hot spot at the thick part of the boss of the flange bolt is introduced into the feeding head (1) to finally shrink the alloy stock solution in the feeding head (1).
8. The low-pressure casting method for the thin-wall complex aluminum alloy gearbox shell according to claim 6, characterized by comprising the following steps of: in the step 3, bosses with the height of about 32-36mm are arranged in 4 reaction pin holes in the inner cavity of the gearbox shell, and cooling pins (4) are arranged above the 4 reaction pin holes in the inner cavity.
9. The low-pressure casting method for the thin-wall complex aluminum alloy gearbox shell according to claim 6, characterized by comprising the following steps of: in the step 3, the thickness of a connecting wall between a transmission case bolt column (5-1) and a bearing hole is 5.5mm, the lower part of the inner runner (3-1) connecting bolt column (5-1) arranged at the pouring gate (3) is subjected to feeding, and the inner runner (3-1) is arranged in the sand core (2).
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| CN114433818B (en) | 2024-05-10 |
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