CN114433818B - 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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- CN114433818B CN114433818B CN202210159525.4A CN202210159525A CN114433818B CN 114433818 B CN114433818 B CN 114433818B CN 202210159525 A CN202210159525 A CN 202210159525A CN 114433818 B CN114433818 B CN 114433818B
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- 238000005266 casting Methods 0.000 title claims abstract description 119
- 238000000034 method Methods 0.000 title claims abstract description 26
- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 16
- 239000000956 alloy Substances 0.000 claims description 43
- 229910045601 alloy Inorganic materials 0.000 claims description 42
- 239000002994 raw material Substances 0.000 claims description 36
- 239000011550 stock solution Substances 0.000 claims description 32
- 239000007788 liquid Substances 0.000 claims description 24
- 238000001816 cooling Methods 0.000 claims description 23
- 238000002844 melting Methods 0.000 claims description 18
- 230000008018 melting Effects 0.000 claims description 18
- 238000004321 preservation Methods 0.000 claims description 18
- 238000007670 refining Methods 0.000 claims description 18
- 238000007711 solidification Methods 0.000 claims description 14
- 230000008023 solidification Effects 0.000 claims description 14
- 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
- 239000011248 coating agent Substances 0.000 claims description 9
- 238000000576 coating method Methods 0.000 claims description 9
- 230000009471 action Effects 0.000 claims description 7
- 238000003723 Smelting Methods 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 6
- 238000005429 filling process Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims description 3
- 230000002093 peripheral effect Effects 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 239000011162 core material Substances 0.000 description 49
- 230000007547 defect Effects 0.000 description 17
- 238000004088 simulation Methods 0.000 description 10
- 238000005457 optimization Methods 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 230000003031 feeding effect Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
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- 239000003973 paint Substances 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
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Classifications
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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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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
Abstract
The invention discloses a low-pressure casting method and a device for a thin-wall complex aluminum alloy gearbox shell, belonging to the technical field of automobile part manufacture.
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 gearbox shell matched with the car engine is relatively simple in structure due to lower load and smaller size, and is mainly produced by adopting aluminum alloy high-pressure casting; because the rear shell of the automatic gearbox for the heavy truck is large in size and high in load, the requirements can be met only by using alloy materials with higher mechanical strength and heat treatment strengthening, and the product with large size and thin wall is manufactured: the overall dimension of the product is 562 x 451 x 308mm, the wall thickness of the overall side wall is 5.5mm, the product is complex in structure, the local wall thickness is uneven, the cast is in different positions, hot joints with the wall thickness of 38-59mm exist, shrinkage porosity defects are easy to form, due to the fact that the product is complex in structure and the wall thicknesses in different positions are different greatly, normal sequential solidification cannot be guaranteed by adopting a common pouring system, and the hot joints can occur in positions with large wall thickness to generate the shrinkage porosity defects.
The invention patent with the application number of CN109175306A provides a casting mould and a casting process of a gearbox body, a casting system of the gravity casting mould is repair welded on the basis of the original mould, a runner water inlet communicated with a casting cavity is arranged on a lower mould, the improved casting mould is provided with a connecting part of a low-pressure casting machine, and the improved low-pressure casting mode can effectively solve the problem that the product is leaked and scrapped due to shrinkage porosity and shrinkage cracking of the gearbox wall at the transition part of rapid thickness change in the casting process.
In the invention patent with the application number of CN110449556A, a casting method of a rear shell of a gearbox is provided, chill is designed for a concentrated part of heat collection of a casting (the joint of a reinforcing rib and a boss on the side surface of the casting is provided with the chill), so that sequential solidification of the casting is realized, casting defects are reduced, the problem that a joint of the reinforcing rib and the boss on the casting is easy to form a hot joint, the casting is difficult to be sequentially solidified, the casting is caused to have casting defects is solved, the sequential solidification of the defective position of the casting is realized under the action of the chill, a compact structure is formed, grains at the position are thinned, and the mechanical property of the casting is improved.
Both the above two patents improve the forming method of castings, but at the thick wall thickness part of the product, a plurality of shrinkage porosity defects exist, and due to the fact that the product is complex in structure and the wall thickness at different positions is quite different, a common pouring system is adopted, normal sequential solidification cannot be ensured, and at the position with large wall thickness, hot spots can occur, so that the shrinkage porosity defects are generated.
If the pouring gate is arranged on the end face of the bearing hole of the gearbox shell, the flange bolt boss is positioned at the topmost end of the casting, the thickness of the flange bolt boss is about 28mm, the wall thickness of the lower connection is 5.5mm, and simulation show that a simple pouring system cannot be sequentially solidified from top to bottom, so that a hot joint is easily generated at the thick and large part of the flange bolt boss. In addition, the height of the gearbox shell is 308mm, the shrinkage porosity defect of the flange bolt boss is difficult to be solved by arranging an inner runner at a pouring gate,
Bosses with the height of about 32-36mm are arranged in 4 reaction pin holes in the inner cavity of the gearbox shell, and simulation shows that hot spots are easy to generate in the interior to form shrinkage cavity defects,
The shrinkage porosity defect of the bolt column, the wall thickness of the connection between the bolt column and the bearing hole of the gearbox shell is 5.5mm, simulation shows that the wall thickness position of 5.5mm is easy to solidify in advance during solidification, the feeding of the bolt column by the pouring gate is blocked, a hot joint is formed in the bolt column, the shrinkage porosity defect is caused,
The large-wall-thickness parts of the end face of the gate of the gearbox housing are not equal to each other and are 72-306mm away from the center of the gate, and simulation shows that a simple gate cannot meet the feeding effect, and hot joints are easy to form at the large-wall-thickness parts, so that shrinkage porosity defects are caused.
Therefore, we propose a low-pressure casting method and device for a thin-wall complex aluminum alloy gearbox shell.
Disclosure of Invention
The invention aims to solve the problems by providing a low-pressure casting method and device for a thin-wall complex aluminum alloy gearbox shell, which adopt a built-in inner runner sand core, core-pulling parts are heated, cooling pins are adopted for cooling locally, flange bolt bosses adopt a comprehensive means of riser feeding, sequential solidification of castings in the low-pressure casting process is comprehensively and thoroughly realized, and the problems that the thickness of the castings is greatly different, the structure is complex, and poor forming and shrinkage porosity are easy to occur in the products are solved.
The invention realizes the aim through the following technical scheme that the low-pressure casting device for the thin-wall complex aluminum alloy gearbox shell comprises a riser, a sand core, a gate and a loose core, wherein a cylindrical feeding channel is formed in the sand core, an inner runner is arranged on the gate, the inner runner is distributed along the shape of the gate, the 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 is characterized in that the core pulling device is arranged at the outer side of the pouring gate and the sand core, the core pulling device is connected with an external pushing hydraulic cylinder, and the upper die, the lower die, the core pulling device, the pouring gate, the riser and the sand core jointly form a forming die of the casting.
Preferably, the molding surface of the sand core is provided with a coating for demolding castings, and the coating is specifically an alcohol-based coating of the Shanghai European area Aiha 1135.
By adopting the scheme, the sand core with the surface sprayed with the paint is utilized to form the outer shape of the gearbox shell, so that the appearance is ensured to be consistent with the roughness formed by the metal mold.
Preferably, the outer wall of the sand core adopts conformal wave patterns.
Through adopting above-mentioned scheme, adopt along with shape wave line, reduced the weight of psammitolite, increased the heated area of core making in-process, can reduce the curing time of core making process, improve core making efficiency, also increased the carminative area of psammitolite in the casting process simultaneously, reduced the resin in the psammitolite material and heated the gas generation, the risk of immersion foundry goods.
Preferably, the sand core is provided with a cooling pin, the cooling pin is inlaid in the upper die, and the cooling pin is specifically a water cooling pipe.
By adopting the scheme, the built-in inner runner sand core is utilized, the core pulling part is heated, the cooling pin is adopted for cooling locally, the flange bolt boss adopts the comprehensive means of riser feeding, the sequential solidification of the casting in the low-pressure casting process is comprehensively and thoroughly realized, the problems of great difference of wall thickness of the casting, complex structure and easy generation of poor forming and shrinkage porosity defects of the product are solved.
A casting method of a low-pressure casting device 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 upper die and the lower die of a die are fixed on a 800 kg low-pressure casting machine, the core pulling is arranged 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, and the preheating temperature of the upper die and the lower die of the die is more than or equal to 350 ℃, and the core pulling temperature is more than or equal to 250 ℃;
2) Raw material proportioning, melting and purifying treatment, namely selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then baking an aluminum melting furnace, putting the prepared alloy raw materials into the aluminum melting furnace for smelting at 780-790 ℃, transferring the raw materials into a low-pressure heat preservation furnace for refining and degassing and deslagging after the raw materials are melted, and carrying out degassing for 2 times by adopting high-purity argon for 15 minutes each time to realize refining to obtain alloy stock solution;
3) The method comprises the steps of injecting alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a liquid lifting pipe, conveying the alloy stock solution subjected to refining impurity removal treatment into the mold through the liquid lifting pipe, filling a mold cavity from bottom to top under the action of certain pressure, solidifying and forming under the pressure, and carrying out liquid lifting, primary filling, secondary filling, pressurizing, pressure maintaining and pressure relief on the mold cavity filling process, wherein residual alloy solution in the liquid lifting pipe flows back into the low-pressure heat preservation furnace after pressure relief.
Preferably, in the step 3, a feeding riser is arranged on the flange bolt boss of the gearbox housing, a solidification sequence from bottom to top is formed, and a hot joint at a thick and large part of the flange bolt boss is introduced into the riser, so that alloy stock solution is finally contracted in the riser.
Preferably, in step 3, bosses with a height of about 32-36mm are arranged in 4 reaction pin holes in the inner cavity of the gearbox shell, simulation shows that hot spots are easy to generate in the inner cavity to form shrinkage cavity defects, and cooling pins are arranged above the 4 reaction pin holes in the inner cavity.
Preferably, in step 3, the wall thickness of the connection between the bolt column of the gearbox housing and the bearing hole is 5.5mm, and simulation shows that the thin-wall position of 5.5mm is easy to solidify in advance during solidification, so that the feeding of the bolt column by the pouring gate is blocked, a hot joint is formed in the bolt column, shrinkage cavity defect is caused, the inner runner arranged at the pouring gate is fed under the connection bolt column, and the inner runner is arranged in the sand core.
Preferably, in step 3, the large-wall-thickness part of the end face of the gate of the gearbox housing is far from the center of the gate, and simulation shows that a simple gate cannot meet the feeding effect, hot knots are easily formed at the large-wall-thickness part, shrinkage porosity is caused, and an inner runner is designed on the gate to strengthen the feeding effect.
The beneficial effects of the invention are as follows:
1. The invention uses 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 roughness formed by the metal mold.
2. According to the invention, the inner runner arranged in the sand core is utilized to feed the bolt columns positioned at different height positions of the gearbox shell, the local hot spots in the bolt columns are led into the inner runner, the problem of local shrinkage of the bolt columns is solved, and meanwhile, the inner runner is designed and connected between the gate center and the inner runner arranged in the sand core in order to ensure the feeding effect of the inner runner arranged in the sand core because the bolt columns are far away from the gate center. The connecting inner runner is mainly formed by lower die metal, is not formed by a sand core, is small in weight and thin, reduces curing time in the core making process, improves core making efficiency on one hand, reduces gas generation amount of the sand core on the other hand, and reduces risks of pinholes and air holes caused by gas immersed in castings. In addition, through the inner runner designed on the pouring gate, the shrinkage problem of the large wall thickness parts of the end face of the pouring gate of the casting is solved.
3. The sand core adopts the shape-following wavy patterns outside, so that the weight of the sand core is reduced, the heated area in the core manufacturing process is increased, the curing time in the core manufacturing process can be reduced, the core manufacturing efficiency is improved, the air exhaust area of the sand core in the casting process is increased, and the risks of heating and air generation of resin in the sand core material and immersing into castings are reduced.
4. According to the invention, the sand core with the built-in inner runner is comprehensively adopted, the core-pulling part is heated, the cooling pin is locally adopted for cooling, the flange bolt boss adopts the comprehensive means of riser feeding, sequential solidification of the casting in the low-pressure casting process is comprehensively and thoroughly realized, and the problems that the thickness of the casting is greatly different, the structure is complex, and the product is easy to produce poor formation and shrinkage porosity are solved.
Drawings
FIG. 1 is a schematic view of a casting apparatus according to the present invention.
Fig. 2 is a schematic view of the bottom structure 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 overall structure of the casting apparatus of the present invention.
FIG. 5 is a schematic view of the gate structure of the present invention.
FIG. 6 is an X-ray inspection of a finished casting according to the present invention.
In the figure: 1. riser, 2, sand core, 2-1, paint, 2-2, follow-up raised grain, 3, pouring gate, 3-1, inner runner, 4, cooling pin, 5, casting, 5-1, bolt column, 6, loose core, 6-1, heating pipe, 7 and cylinder feeding channel.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the 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 gate 3 and a core pulling 6, wherein a cylindrical feeding channel 7 is formed in the sand core 2, an inner runner 3-1 is arranged on the gate 3, the inner runner 3-1 is distributed along the shape of the gate 3, the problem of shrinkage porosity of large wall thickness parts at all positions of the end face of a casting gate is solved through an inner runner designed on the gate 3, the 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 6 is arranged at the outer sides 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 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 FIG. 3, the molding surface of the sand core 2 is provided with a coating 2-1 for demolding a casting 5, and the coating 2-1 is specifically an alcohol-based coating of Shanghai European area Aiha 1135.
When the invention is practically used, the sand core 2 of the surface spray coating 2-1 is used for forming the outer shape of the gearbox shell, so that 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 fig. 2, the outer wall of the sand core 2 adopts conformal corrugation 2-2.
When the invention is practically used, the shape-following wavy patterns 2-2 are adopted, so that the weight of the sand core 2 is reduced, the heated 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 2 in the casting process is increased, and the risks of heating and gas generation of resin in the sand core 2 material and immersing into the casting 5 are reduced.
As a technical optimization scheme of the invention, as shown in figures 1 and 4, a cooling pin 4 is arranged on a sand core 2, the cooling pin 4 is inlaid in an upper die, a casting is arranged at the bottom of the upper die and 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 in actual use, the core-pulling 6 is partially heated and is partially cooled by the cooling pin 4, the flange bolt boss adopts the comprehensive means of feeding the riser 1, the sequential solidification of the casting 5 in the low-pressure casting process is comprehensively and thoroughly realized, and the problems of great wall thickness difference of the casting 5, complex structure and easy generation of poor forming and shrinkage porosity defects of the product are solved.
A casting method of a low-pressure casting device 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 upper die and the lower die of the die are fixed on a 800 kg low-pressure casting machine, the core pulling 6 is arranged 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 of the upper die and the core pulling 6 of the die is more than or equal to 250 ℃, a riser 1, a pouring gate 3 and a casting 5 are formed by matching alloy stock solutions through the die and the sand core 2, and the casting 5 is formed by matching the upper die, the lower die, the core pulling 6, the pouring gate 3, the riser 1 and the sand core 2;
2) Raw material proportioning, melting and purifying treatment, namely selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then baking an aluminum melting furnace, putting the prepared alloy raw materials into the aluminum melting furnace for smelting at 780-790 ℃, transferring the raw materials into a low-pressure heat preservation furnace for refining and degassing and deslagging after the raw materials are melted, and carrying out degassing for 2 times by adopting high-purity argon for 15 minutes each time to realize refining to obtain alloy stock solution;
3) The method comprises the steps of injecting alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a liquid lifting pipe, conveying the alloy stock solution subjected to refining impurity removal treatment into the mold through the liquid lifting pipe, filling a mold cavity from bottom to top under the action of certain pressure, solidifying and forming under the pressure, and carrying out liquid lifting, primary filling, secondary filling, pressurizing, pressure maintaining and pressure releasing on the mold cavity filling process, wherein residual alloy solution in the liquid lifting pipe flows back into the low-pressure heat preservation furnace after pressure releasing;
example 2
A casting method of a low-pressure casting device 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 upper die and the lower die of the die are fixed on a 800 kg low-pressure casting machine, the core pulling 6 is arranged 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 of the upper die and the core pulling 6 of the die is more than or equal to 250 ℃, a riser 1, a pouring gate 3 and a casting 5 are formed by matching alloy stock solutions through the die and the sand core 2, and the casting 5 is formed by matching the upper die, the lower die, the core pulling 6, the pouring gate 3, the riser 1 and the sand core 2;
2) Raw material proportioning, melting and purifying treatment, namely selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then baking an aluminum melting furnace, putting the prepared alloy raw materials into the aluminum melting furnace for smelting at 780-790 ℃, transferring the raw materials into a low-pressure heat preservation furnace for refining and degassing and deslagging after the raw materials are melted, and carrying out degassing for 2 times by adopting high-purity argon for 15 minutes each time to realize refining to obtain alloy stock solution;
3) The method comprises the steps of injecting alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a liquid lifting pipe, conveying the alloy stock solution subjected to refining impurity removal treatment into the mold through the liquid lifting pipe, filling a mold cavity from bottom to top under the action of certain pressure, solidifying and forming under the pressure, and carrying out liquid lifting, primary filling, secondary filling, pressurizing, pressure maintaining and pressure releasing on the mold cavity filling process, wherein residual alloy solution in the liquid lifting pipe flows back into the low-pressure heat preservation furnace after pressure releasing;
In step 3, a feeding head 1 is arranged on a flange bolt boss of a gearbox shell to form a solidification sequence from bottom to top, and a hot joint at a thick and large part of the flange bolt boss is introduced into the feeding head 1 to finally shrink alloy stock solution in the feeding head 1.
Example 3
A casting method of a low-pressure casting device 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 upper die and the lower die of the die are fixed on a 800 kg low-pressure casting machine, the core pulling 6 is arranged 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 of the upper die and the core pulling 6 of the die is more than or equal to 250 ℃, a riser 1, a pouring gate 3 and a casting 5 are formed by matching alloy stock solutions through the die and the sand core 2, and the casting 5 is formed by matching the upper die, the lower die, the core pulling 6, the pouring gate 3, the riser 1 and the sand core 2;
2) Raw material proportioning, melting and purifying treatment, namely selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then baking an aluminum melting furnace, putting the prepared alloy raw materials into the aluminum melting furnace for smelting at 780-790 ℃, transferring the raw materials into a low-pressure heat preservation furnace for refining and degassing and deslagging after the raw materials are melted, and carrying out degassing for 2 times by adopting high-purity argon for 15 minutes each time to realize refining to obtain alloy stock solution;
3) The method comprises the steps of injecting alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a liquid lifting pipe, conveying the alloy stock solution subjected to refining impurity removal treatment into the mold through the liquid lifting pipe, filling a mold cavity from bottom to top under the action of certain pressure, solidifying and forming under the pressure, and carrying out liquid lifting, primary filling, secondary filling, pressurizing, pressure maintaining and pressure releasing on the mold cavity filling process, wherein residual alloy solution in the liquid lifting pipe flows back 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 and simulation show that hot spots are easy to generate 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 casting method of a low-pressure casting device 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 upper die and the lower die of the die are fixed on a 800 kg low-pressure casting machine, the core pulling 6 is arranged 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 of the upper die and the core pulling 6 of the die is more than or equal to 250 ℃, a riser 1, a pouring gate 3 and a casting 5 are formed by matching alloy stock solutions through the die and the sand core 2, and the casting 5 is formed by matching the upper die, the lower die, the core pulling 6, the pouring gate 3, the riser 1 and the sand core 2;
2) Raw material proportioning, melting and purifying treatment, namely selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then baking an aluminum melting furnace, putting the prepared alloy raw materials into the aluminum melting furnace for smelting at 780-790 ℃, transferring the raw materials into a low-pressure heat preservation furnace for refining and degassing and deslagging after the raw materials are melted, and carrying out degassing for 2 times by adopting high-purity argon for 15 minutes each time to realize refining to obtain alloy stock solution;
3) The method comprises the steps of injecting alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a liquid lifting pipe, conveying the alloy stock solution subjected to refining impurity removal treatment into the mold through the liquid lifting pipe, filling a mold cavity from bottom to top under the action of certain pressure, solidifying and forming under the pressure, and carrying out liquid lifting, primary filling, secondary filling, pressurizing, pressure maintaining and pressure releasing on the mold cavity filling process, wherein residual alloy solution in the liquid lifting pipe flows back into the low-pressure heat preservation furnace after pressure releasing;
As a technical optimization scheme of the invention, in the step 3, the wall thickness of the connection between the bolt column 5-1 of the gearbox shell and the bearing hole is 5.5mm, simulation shows that the thin-wall position of 5.5mm is easy to solidify in advance during solidification, the feeding of the bolt column 5-1 by the pouring gate 3 is blocked, a hot joint is formed in the bolt column 5-1, shrinkage porosity defect is caused, an inner runner 3-1 arranged at the pouring gate 3 is connected with the lower part of the bolt column 5-1 for feeding, and the inner runner 3-1 is arranged in the 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 characteristics 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 disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in detail below, and that the embodiments described in the examples may be combined as appropriate to form other embodiments that will be apparent to those skilled in the art.
Claims (2)
1. A low-pressure casting device for a thin-wall complex aluminum alloy gearbox shell is characterized in that: the casting mold comprises an upper mold, a lower mold, a riser (1), a sand core (2), a gate (3) and a core pulling (6), wherein a cylindrical feeding channel (7) is formed in the sand core (2), an inner runner (3-1) is arranged on the gate (3), the inner runner (3-1) is distributed along the shape of the gate (3), the gate (3) and the sand core (2) are connected through the cylindrical feeding channel (7) and the inner runner (3-1) in a matched manner, and the inner runner (3-1) is communicated with a bolt column (5-1) of a gearbox casing casting (5);
the loose core (6) is arranged on the outer sides of the pouring gate (3) and the sand core (2), the loose core (6) is connected with an external pushing hydraulic cylinder, and the upper die, the lower die, the loose core (6), the pouring gate (3), the riser (1) and the sand core (2) jointly form a forming die of the gearbox casing casting (5);
The molding surface of the sand core (2) is provided with a coating (2-1) for demolding a gearbox shell casting (5), and the coating (2-1) is an alcohol-based coating;
the outer wall of the sand core (2) adopts conformal wave patterns (2-2);
a cooling pin (4) is arranged on the sand core (2), the cooling pin (4) is embedded in the upper die, and the cooling pin (4) is a water cooling pipe;
a heating pipe (6-1) is arranged in the core pulling (6);
a feeding riser is arranged on a flange bolt boss of a casting of the gearbox shell, a solidification sequence from bottom to top is formed, and a hot joint at a thick and large part of the flange bolt boss is introduced into the feeding riser, so that alloy stock solution is finally contracted in the feeding riser;
bosses with the height of 32-36mm are arranged in 4 reaction pin holes in the inner cavity of the gearbox shell casting, and cooling pins (4) are arranged above the 4 reaction pin holes in the inner cavity;
The wall thickness of the connection between the gearbox casing casting bolt column (5-1) and the bearing hole is 5.5mm, the inner runner (3-1) arranged at the gate (3) is connected with the lower part of the bolt column (5-1) for feeding, and the inner runner (3-1) is arranged in the sand core (2).
2. The casting method of the low-pressure casting device for the thin-wall complex aluminum alloy gearbox shell according to claim 1, comprising the following steps:
1) Assembling and preheating a casting device, namely assembling an upper die, a lower die, a riser (1), a gate (3), a core pulling (6) and a sand core (2) of the casting device, wherein the upper die and the lower die are fixed on a 800 kg low-pressure casting machine, the core pulling (6) is arranged on a peripheral guide rail of the lower die, the upper die, the lower die and the core pulling (6) are preheated before casting, and the preheating temperature of the upper die and the lower die is more than or equal to 350 ℃, and the core pulling temperature is more than or equal to 250 ℃;
2) Raw material proportioning, melting and purifying treatment, namely selecting corresponding raw materials according to actual requirements, proportioning and mixing the raw materials, then baking an aluminum melting furnace, putting the prepared raw materials into the aluminum melting furnace for smelting at 780-790 ℃, transferring the raw materials into a low-pressure heat preservation furnace for refining and degassing and deslagging after the raw materials are melted, and carrying out degassing for 2 times by adopting high-purity argon for 15 minutes each time to realize refining to obtain alloy stock solution;
3) The method comprises the steps of injecting alloy stock solution, connecting a low-pressure heat preservation furnace containing the alloy stock solution with a mold through a liquid lifting pipe, conveying the alloy stock solution subjected to refining impurity removal treatment into a forming mold through the liquid lifting pipe, filling a mold cavity from bottom to top under the action of certain pressure, solidifying and forming under the pressure, and carrying out liquid lifting, primary filling, secondary filling, pressurizing, pressure maintaining and pressure releasing on the mold cavity in the filling process, wherein residual alloy stock solution in the liquid lifting pipe flows back into the low-pressure heat preservation furnace after pressure releasing.
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| CN114433818A (en) | 2022-05-06 |
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