Sand mold casting process suitable for aluminum alloy shell of high-power electric transmission device
The sand core of the hollow structure is manufactured through three-dimensional molding software design and 3DP printing, combining lock rod tightening and high-pressure water gun cleaning, and solving the difficulty of sand core positioning and process hole repair during casting and molding of the aluminum alloy shell of the high-power electric transmission device. The problem of this paper improves the structural compactness and mechanical properties of the castings, ensuring the cleanliness and airtightness of the water-cooled channel.
Patent Information
- Application Number
- CN202411411447.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-10
- Publication Date
- 2025-01-14
AI Technical Summary
During the casting process of the aluminum alloy shell of high-power electric transmission device, there are problems such as inaccurate positioning of the sand core, difficult welding of casting process holes, air holes, pinholes and shrinkage defects, resulting in low tissue density and mechanical properties. Moreover, the sand core is difficult to clean, which affects the air tightness and the cleanliness of the water-cooled channel.
The casting system and retracting system are designed using three-dimensional molding software, and the castings are accelerated by cold iron, and the riser is set to solve local thickness problems. The process simulation is carried out through MAGMA software; the sand core with hollow structure is manufactured by 3DP printing and the exhaust is designed. The holes and through holes are combined with the lock rod to tighten the sand type, and the vibration sand drop and high-pressure water gun are used to clean the holes, and the process holes are roughly processed and repaired to solve the above problems.
Improve the structural tightness and mechanical properties of the castings, ensure the molding integrity and dimensional accuracy of the sand core, reduce the complexity of process hole repair welding, ensure the cleanliness of the water-cooled channel and the air-tightness of the castings, and meet the product Design requirements.
Smart Images
Figure CN119304124A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of sand casting technology, and in particular relates to a sand casting technology suitable for an aluminum alloy housing of a high-power electric transmission device. Background Art
[0002] With the development of transmission technology, special vehicles have evolved from traditional mechanical transmission to electric transmission or electromechanical composite transmission. As a key component of the electric transmission device, the aluminum alloy shell is usually designed with complex water cooling channels inside to cool the motor during operation. The aluminum alloy shell serves as the outer wall of the water cooling system of the electric transmission device and is equipped with other components. It is required that there should be no water seepage or deformation during operation. In addition, the high-power electric transmission device equipped on special vehicles has greater power than the electric transmission device of household new energy vehicles, and the working environment is more severe, so higher requirements are placed on its tissue density and mechanical properties.
[0003] Since the water-cooling channel inside the aluminum alloy shell is nearly closed, the sand core forming the inner cavity of the casting is almost surrounded by the high-temperature aluminum alloy liquid during the filling and solidification process. The sand core produces a large amount of gas in the high-temperature environment, which is easy to invade the aluminum alloy liquid, resulting in pores, pinholes, and shrinkage defects in the casting, and the internal structure is not dense, resulting in the air tightness failing to meet the design requirements after processing. At the same time, due to the structural characteristics of the nearly closed water-cooling channel inside the aluminum alloy shell, if the process hole is not opened on the casting during the casting process design, the sand core cannot be effectively positioned, and the dimensional accuracy of the casting cannot be guaranteed. There is also great difficulty in cleaning the sand core inside the casting blank. After the sand is shaken off, it is difficult to clean the sand core inside the casting only through the process hole, and the cleanliness of the water-cooling channel cannot be guaranteed. The repair welding of the casting process hole is also one of the difficulties in the casting production of aluminum alloy shells. If the product is not to leak in the later stage, the opened process hole must be welded full, but it is difficult to ensure that the welding slag does not fall into the water-cooling channel during the welding process. Therefore, there are still many technical difficulties in the casting process of the aluminum alloy shell of the high-power electric transmission device. Summary of the invention
[0004] In view of the technical problems existing in the casting process of the aluminum alloy shell of the existing high-power electric transmission device, such as inaccurate sand core positioning and difficulty in welding the process holes of the casting, the present invention provides a sand casting process suitable for the aluminum alloy shell of the high-power electric transmission device, which effectively solves the casting defects and improves the quality of the casting.
[0005] The technical solution adopted by the present invention is as follows: A sand casting process suitable for an aluminum alloy shell of a high-power electric transmission device. According to the structural characteristics of the aluminum alloy shell of the high-power electric transmission device, a pouring system, a shrinkage feeding system and a chiller of the casting are designed by using three-dimensional modeling software; chillers are arranged on the inner and outer surfaces of the aluminum alloy shell to accelerate the cooling speed of the casting during solidification, so as to solve the problem of pinhole defects caused by gas precipitation in aluminum liquid during the solidification process of the casting; a riser is arranged on the upper end surface of the aluminum alloy shell to solve the problem of shrinkage feeding in locally thick and large parts of the casting; MAGMA software is used to simulate and optimize the casting process, so as to determine the best casting process plan.
[0006] Furthermore, the best casting process is the sand gravity casting process, and its sand mold assembly includes 4 sand molds and 3 sand cores, sand mold-1#, sand mold-2#, sand mold-3#, sand mold-4#, sand core-1#, sand core-2#, and sand core-3#. The 4 sand molds are assembled together through positioning bosses to form the outer contour of the casting and the pouring system; sand core-1# and sand core-2# are both positioned on sand core-2# through core heads; sand core-3# is installed on sand mold-4# through positioning grooves to form a complete sand mold assembly.
[0007] Furthermore, the sand mold-1# is used for forming the casting pouring system, and a ceramic filter is installed on the cross runner, which is used to filter out the oxidized slag inclusions in the aluminum liquid during the casting pouring to purify the aluminum liquid.
[0008] Furthermore, sand core-1# is used to form the water-cooling channel of the aluminum alloy shell. It is a hollow structure with several φ1mm exhaust holes inside. The exhaust holes surround the sand core and lead to the sand mold through the core head. Due to its unique structure, sand core-1# needs to be printed by 3DP; φ3~5mm exhaust holes are punched in the corresponding parts of sand mold-1#, sand mold-2# and sand core-1# core head to connect the sand core-1# exhaust holes with the outside. At the same time, sand core-1# uses the process holes opened on the lower end face of the casting as a support point to ensure that it has sufficient supporting strength when installed on sand mold-2#.
[0009] Furthermore, locking rod grooves are provided on both sides of the four sand molds, namely, sand mold-1#, sand mold-2#, sand mold-3#, and sand mold-4#. After the aluminum alloy shell sand mold assembly is assembled, the sand mold is fastened with a threaded locking rod to prevent the sand mold from shifting during the sand mold transportation and pouring process, thereby facilitating the boxless molding adopted in the present invention.
[0010] Furthermore, the sand gravity casting process includes molding and core making, core assembly, smelting, pouring, cleaning, processing of process holes and process blocks, and process hole repair welding, which specifically includes the following steps: Step 1, modeling and core making: use 3DP printing to make sand core-1#, use furan resin sand manual modeling to make sand mold-1#, sand mold-2#, sand mold-3#, sand mold-4#, sand core-2#, sand core-3#; first apply a layer of alcohol-based paint on the sand core and sand mold cavity, and then apply a layer of water-based paint; then bake at 80~90℃ for 12~14h, and cool with the furnace; Step 2, core assembly: first assemble sand mold-2# onto sand mold-1#, then assemble sand core-1#, sand core-2#, and sand mold-3# onto sand mold-2# in sequence, assemble sand mold-4# onto sand mold-3#, and then assemble sand core-3# onto sand mold-4#, and finally use a threaded locking rod to fasten the assembled sand mold; Step 3, smelting: when the temperature of ZL114A alloy liquid is 710-720°C, 0.4%-0.6% AlSr10 master alloy of ZL114A alloy liquid is used for modification; when the temperature rises to 720-730°C, argon gas is used for rotary purification for 10-15 minutes; and when the temperature drops to 710-720°C, 0.4%-0.6% TCB alloy of ZL114A alloy liquid is added for refinement treatment; Step 4, pouring: pouring the ZL114A alloy liquid at a temperature of 690-700°C; Step 5, cleaning: first use vibration to shake off the sand mold, then place the casting with sand core at a temperature of 400-500°C, bake for 4-5 hours, cool with the furnace, clean the casting with a high-pressure water gun, and finally use an endoscope to check whether the water channel inside the aluminum alloy shell is clean; Step 6, machining process holes and process blocks: rough machining the process holes of the casting, and at the same time machining the process blocks, process holes and process blocks. The surface roughness is required to reach Ra6.3 after machining, and the fitting tolerance is interference fit; Step 7, process hole repair welding: first drive the process block into the process hole to form a tight fit, and then use ZL114A special aluminum alloy welding wire for repair welding to fill the process hole.
[0011] The beneficial effects of the present invention are: 1. The present invention adopts 3DP printing process to manufacture the sand core required for forming the water cooling channel inside the aluminum alloy shell, which ensures the integrity and dimensional accuracy of the sand core molding; the sand core is designed as a hollow structure by 3DP printing, and several φ1mm exhaust holes are distributed inside, and a tool is used to drill a φ3-5mm through hole at the sand mold part corresponding to the core head of the sand core, so that the sand core exhaust hole can penetrate inside and outside the sand mold, so as to solve the exhaust problem of the sand core during the casting process; 2. The present invention opens the process hole on the lower end surface of the aluminum alloy shell, which can not only provide better support for the sand core, but also the lower end surface is a machined plane, which can effectively reduce the workload of cleaning and grinding the process hole after repair welding.
[0012] 3. When smelting ZL114A aluminum alloy in the present invention, after completing the modification and rotation purification, TCB alloy (such as 0.5wt.%) is added for refinement treatment, which not only refines the grains of the aluminum alloy, improves the fluidity of the alloy liquid, and improves the structural density of the casting, but also improves the mechanical properties of the casting.
[0013] 4. When cleaning the casting, the present invention first uses the method of vibrating sand removal to clean the sand mold and sand core outside the casting, and then uses the method of baking sand removal to clean the sand core inside the casting, thereby solving the problem that the sand core of the aluminum alloy shell of the high-power electric transmission device is difficult to clean.
[0014] 5. When plugging the process hole of the casting, the present invention first processes the process hole and the process block, then drives the process block into the process hole, and finally performs repair welding to plug the process hole. Instead of using the traditional method of directly repairing the process hole by repair welding, the problem of welding slag dripping into the inner cavity of the casting and blocking the water cooling channel when welding and plugging the process hole of the casting can be effectively solved.
[0015] In short, the process of the present invention reduces the casting defects of the aluminum alloy housing of high-power electric transmission and improves the quality of castings. The castings produced meet the product design requirements and have excellent quality after flaw detection, water pressure test, bench test and sports car test. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a schematic diagram of the structure of the aluminum alloy shell.
[0017] Figure 2 It is a structural schematic diagram of the aluminum alloy shell sand mold assembly in a loosened state; In the figure: 1. Sand mold-1#, 2. Sand mold-2#, 3. Sand mold-3#, 4-Sand mold-4#, 5. Sand core-1#, 6. Sand core-2#, 7. Sand core-3#.
[0018] Figure 3 It is a structural schematic diagram of the aluminum alloy shell sand mold assembly in the assembled state.
[0019] Figure 4 This is a schematic diagram of the structure of aluminum alloy shell sand mold-1#.
[0020] Figure 5 This is a schematic diagram of the structure of aluminum alloy shell sand mold-2#.
[0021] Figure 6 This is a schematic diagram of the structure of aluminum alloy shell sand mold-3#.
[0022] Figure 7 This is a schematic diagram of the structure of aluminum alloy shell sand mold-4#.
[0023] Figure 8 This is a schematic diagram of the structure of aluminum alloy shell sand core-1#.
[0024] Fig. 9 This is a schematic diagram of the structure of aluminum alloy shell sand core-2#.
[0025] Fig.10 This is a schematic diagram of the structure of aluminum alloy shell sand core-3#. DETAILED DESCRIPTION
[0026] The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited thereto.
[0027] The sand casting process of the present invention, which is applicable to the aluminum alloy housing of a high-power electric transmission device, includes molding and core making, core assembly, smelting, pouring, cleaning, processing of process holes and process blocks, and process hole repair welding. The specific operation steps are as follows: Step 1, molding and core making: use 3DP printing to make sand core-1#, and use furan resin sand manual molding to make sand mold-1#, sand mold-2#, sand mold-3#, sand mold-4#, sand core-2#, and sand core-3#; first apply a layer of alcohol-based coating on the sand core and sand mold cavity, and then apply a layer of water-based coating; then place it at a temperature of 80~90℃ and bake it for 12h, and cool it with the furnace.
[0028] Step 2, core assembly: first assemble sand mold-2# on sand mold-1#, then assemble sand core-1#, sand core-2#, and sand mold-3# on sand mold-2# in sequence, assemble sand mold-4# on sand mold-3#, and then assemble sand core-3# on sand mold-4#, and finally use a threaded locking rod to tighten the assembled sand mold.
[0029] Step 3, smelting: when the temperature of ZL114A alloy liquid is 710-720°C, 0.5% of AlSr10 master alloy by weight of ZL114A alloy liquid is used for modification; when the temperature rises to 720-730°C, argon gas is used for rotary purification for 10 minutes; and then when the temperature drops to 710-720°C, 0.5% of TCB alloy by weight of ZL114A alloy liquid is added for refinement treatment.
[0030] Step 4, pouring: pouring the ZL114A alloy liquid at a temperature of 690-700°C.
[0031] Step 5, cleaning: first use vibration to shake off the sand mold, then place the casting with sand core at a temperature of 400-500℃, bake for 4-5 hours, cool with the furnace, clean the casting with a high-pressure water gun, and finally use an endoscope to check whether the water channel inside the aluminum alloy shell is clean.
[0032] Step 6, machining process holes and process blocks: Rough-machine the process holes of the castings, and at the same time machine the process blocks. After the process holes and process blocks are machined, the surface roughness must reach Ra6.3, and the fitting tolerance is interference fit.
[0033] Step 7, process hole repair welding: first drive the process block into the process hole to form a tight fit, and then use ZL114A special aluminum alloy welding wire for repair welding to fill the process hole.
Claims
1. A sand casting process suitable for aluminum alloy housing of high-power electric transmission device, characterized in that: According to the structural characteristics of the aluminum alloy shell of the high-power electric transmission device, the pouring system, shrinkage feeding system and chiller of the casting are designed using 3D modeling software. Chills are set on the inner and outer surfaces of the aluminum alloy shell, and risers are set on the upper end surface of the aluminum alloy shell. MAGMA software is used to simulate and optimize the casting process to determine the best casting process plan.
2. The sand casting process for aluminum alloy housing of high-power electric transmission device according to claim 1 is characterized in that: The optimal casting process scheme is a sand mold gravity casting process, and its sand mold assembly includes 4 sand molds and 3 sand cores, sand mold-1#, sand mold-2#, sand mold-3#, sand mold-4#, sand core-1#, sand core-2#, and sand core-3#; the 4 sand molds are assembled together through positioning bosses to form the outer contour of the casting and the pouring system; the sand core-1# and sand core-2# are both positioned on the sand core-2# through the core head; the sand core-3# is installed on the sand mold-4# through the positioning groove to form a complete sand mold assembly.
3. The sand casting process for aluminum alloy housing of high-power electric transmission device according to claim 2 is characterized in that: The sand mold-1# is used for forming a casting pouring system, and a ceramic filter is installed on the cross runner.
4. The sand casting process for aluminum alloy housing of high-power electric transmission device according to claim 2 is characterized in that: The sand core-1# is used to form the water-cooling channel of the aluminum alloy shell. It is a hollow structure with several φ1mm exhaust holes inside. The exhaust holes surround the sand core and lead to the sand mold through the core head. Sand core-1# is printed by 3DP; φ3~5mm exhaust holes are punched at the corresponding positions of sand mold-1#, sand mold-2# and sand core-1# core head to connect the sand core-1# exhaust holes with the outside. At the same time, sand core-1# uses the process hole opened on the lower end face of the casting as a support point.
5. The sand casting process for aluminum alloy housing of high-power electric transmission device according to claim 2 is characterized in that: The four sand molds, sand mold-1#, sand mold-2#, sand mold-3#, and sand mold-4#, are all provided with locking rod grooves on both sides. After the aluminum alloy shell sand mold assembly is assembled, the sand mold is fastened with a threaded locking rod to prevent the sand mold from shifting during the sand mold transportation and pouring process.
6. The sand casting process for aluminum alloy housing of high-power electric transmission device according to claim 2 is characterized in that: The sand gravity casting process includes molding and core making, core assembly, smelting, pouring, cleaning, processing process holes and process blocks, and process hole repair welding, which specifically includes the following steps: Step 1, modeling and core making: use 3DP printing to make sand core-1#, use furan resin sand manual modeling to make sand mold-1#, sand mold-2#, sand mold-3#, sand mold-4#, sand core-2#, sand core-3#; first apply a layer of alcohol-based paint on the sand core and sand mold cavity, and then apply a layer of water-based paint; then bake at 80~90℃ for 12~14h, and cool with the furnace; Step 2, core assembly: first assemble sand mold-2# onto sand mold-1#, then assemble sand core-1#, sand core-2#, and sand mold-3# onto sand mold-2# in sequence, assemble sand mold-4# onto sand mold-3#, and then assemble sand core-3# onto sand mold-4#, and finally use a threaded locking rod to fasten the assembled sand mold; Step 3, smelting: when the temperature of ZL114A alloy liquid is 710-720°C, 0.4%-0.6% AlSr10 master alloy of ZL114A alloy liquid is used for modification; when the temperature rises to 720-730°C, argon gas is used for rotary purification for 10-15 minutes; and when the temperature drops to 710-720°C, 0.4%-0.6% TCB alloy of ZL114A alloy liquid is added for refinement treatment; Step 4, pouring: pouring the ZL114A alloy liquid at a temperature of 690-700°C; Step 5, cleaning: first use vibration to shake off the sand mold, then place the casting with sand core at a temperature of 400-500°C, bake for 4-5 hours, cool with the furnace, clean the casting with a high-pressure water gun, and finally use an endoscope to check whether the water channel inside the aluminum alloy shell is clean; Step 6, machining process holes and process blocks: rough machining the process holes of the casting, and at the same time machining the process blocks, process holes and process blocks. The surface roughness is required to reach Ra6.3 after machining, and the fitting tolerance is interference fit; Step 7, process hole repair welding: first drive the process block into the process hole to form a tight fit, and then use ZL114A special aluminum alloy welding wire for repair welding to fill the process hole.