Production process of aluminum transmission gearbox shell part

Abstract

The invention relates to the technical field of automobile part manufacturing, in particular to a production process of an aluminum transmission gearbox shell part, which comprises the following process steps: a cold chamber die-casting machine injects molten aluminum into a die of the transmission gearbox shell part for die-casting formation to obtain a die-casting blank part; the die-casting blank is placed in a lower die positioning area of an oil pressure punching machine, the oil pressure punching machine is started, a water gap in the outer side of the die-casting blank is removed, and a die-casting piece is obtained; the belt sander is used for polishing cinder ladles on the peripheral edges of the die casting; the CNC machine tool is started to conduct drilling machining on the polished die casting; the die casting is hung on a hanging tool and fed into a shot blasting device, and burrs on the die casting are removed after shot blasting treatment; sequentially carrying out ultrasonic cleaning and passivating treatment on the deburred die casting to obtain a semi-finished product of the transmission gearbox shell; and spraying powder on the semi-finished product of the transmission gearbox shell part, and baking and curing to obtain a finished product of the transmission gearbox shell part.

Description

Technical Field

[0001] This invention relates to the technical field of automotive parts manufacturing, and in particular to a manufacturing process for an aluminum transmission gearbox housing. Background Technology

[0002] In recent years, the automotive industry has developed rapidly. As a key component of the automotive powertrain, the performance and quality of the transmission are crucial to the overall performance of the vehicle. The transmission gearbox housing, as an important part of the transmission, must not only provide reliable support and protection for internal components but also meet various requirements such as lightweighting and high strength. Aluminum, due to its low density, high strength, and good heat dissipation, has gradually become an ideal choice for manufacturing transmission gearbox housings.

[0003] An aluminum transmission gearbox housing (see reference) Figure 1 The device includes a bottom shell 1, on which a mounting base 2 and multiple mounting posts 3 are provided. The mounting base 2 is provided with a first mounting groove 21 and a second mounting groove 22, which are perpendicular to each other. The first mounting groove 21 is provided with a concentric circular stepped structure. The gearbox housing parts produced by traditional manufacturing processes have obvious defects. Simple cleaning is not enough to guarantee the cleanliness and protection of the product, resulting in insufficient surface cleaning of the housing parts, which affects the passivation effect. The product surface has uneven passivation problems, which further affects the effect of subsequent powder coating and curing, and affects the quality and service life of the aluminum gearbox housing parts.

[0004] Therefore, developing a manufacturing process for aluminum transmission gearbox housings to address the problem of uneven passivation in existing technologies, which affects the subsequent powder coating and curing effect, has become an important issue that urgently needs to be addressed. Summary of the Invention

[0005] To address the technical problem of uneven passivation on the product surface in existing manufacturing processes, which affects the subsequent powder coating and curing effect, and to further improve the quality of transmission gearbox housing parts, this application provides a manufacturing process for aluminum transmission gearbox housing parts.

[0006] A manufacturing process for an aluminum transmission gearbox housing includes the following steps: S1: The cold chamber die casting machine injects molten aluminum into the mold of the gearbox housing part and die-casts it to obtain a die-cast blank; S2: Place the die-cast blank into the lower die positioning area of ​​the hydraulic press, and after clamping it stably, start the hydraulic press to remove the sprue on the outside of the die-cast blank to obtain the die-cast part; S3: The belt sander grinds the slag pockets around the perimeter of the die casting. S4: Start the CNC machine tool to drill the first mounting slot of the die-cast part after S3 grinding; S5: Hang the die-cast parts processed in S4 on the hanger, send the hanger into the shot blasting device, and after shot blasting, use tools to remove the burrs on the die-cast parts. S6: The die-cast parts that have been deburred in S5 are sequentially subjected to ultrasonic cleaning, rinsing, passivation treatment, rinsing and drying to obtain a semi-finished product of the gearbox housing. S7: The semi-finished transmission gearbox housing is powder-coated and baked to cure, thus obtaining the finished transmission gearbox housing.

[0007] Through the above technical solution, in step S1, molten aluminum is injected into a mold using a cold chamber die-casting machine to form a die-cast blank, ensuring the initial forming quality of the gearbox housing and guaranteeing basic structural integrity. In step S2, the die-cast blank is placed in a hydraulic press to remove the sprue, resulting in a more regular shape and providing a good foundation for subsequent processing. In step S3, a belt abrasive is used to grind the slag pockets around the die-cast part, making the surface smoother and reducing surface defects. In step S4, drilling is performed using a CNC machine tool to precisely form the required holes on the die-cast part. The holes are designed to meet assembly and usage requirements; Step S5 involves shot blasting and deburring the die casting to make its surface smoother, improving its surface quality and corrosion resistance; Step S6 involves ultrasonic cleaning, rinsing, passivation, rinsing, and drying to effectively remove impurities and oil from the die casting surface, while forming a uniform and dense passivation film on the outer casing surface, further laying the foundation for powder coating and curing, resulting in a semi-finished transmission gearbox outer casing; In Step S7, the semi-finished transmission gearbox outer casing is powder coated and baked to cure, finally yielding the finished transmission gearbox outer casing.

[0008] The manufacturing process of this application involves a series of consecutive steps, including die casting, sprue cleaning, grinding, drilling, shot blasting, surface treatment, and powder coating curing, forming a complete production process for aluminum transmission gearbox housing parts. By performing multi-step cleaning treatment on the surface of the aluminum transmission gearbox housing parts, a uniform and dense passivation film can be formed on the surface of the product, which improves the effect of powder coating curing and enhances the corrosion resistance and service life of the product.

[0009] Further, S1 includes the following steps: S11: Clean the mold cavity of the gearbox housing component, and spray punch lubricant and mold release agent into the mold cavity in sequence; S12: Molten aluminum at 650℃±20℃ is injected into the mold through an injection punch and held under a pressure of 80-120MPa. The injection filling time is 4-6s, the holding time is 10-15s, and the mold preheating temperature is 180-250℃. S13: After cooling, open the mold and remove the die-cast blank.

[0010] Through the above technical solutions, cleaning the mold cavity before die casting can effectively remove impurities and residues, providing a clean environment for the subsequent die casting process and preventing impurities from mixing into the molten aluminum and affecting the quality of the die-cast blank. Secondly, spraying the punch lubricant can reduce the friction between the injection punch and the mold, ensuring smooth injection of molten aluminum into the mold and extending the service life of the injection punch. The release agent helps to open the mold smoothly after die casting, allowing the die-cast blank to be removed intact from the mold, reducing the occurrence of mold sticking, and improving production efficiency and product quality. Injecting molten aluminum at 650℃±20℃ into the mold under a boosted pressure of 80-120MPa, the molten aluminum in this temperature range has good fluidity and filling properties, which can fully fill all corners of the mold, ensuring the forming quality of the die-cast blank and reducing adverse phenomena such as cold shuts, watermarks, shrinkage, and depressions. Furthermore, after cooling, the die-cast blank is opened and removed, completing the die casting process and providing a foundation for subsequent processing.

[0011] Further, S2 includes the following steps: S21: Remove slag pockets from the edges of the die-cast blank; S22: Cleaning impurities on the upper and lower molds of the hydraulic press by spraying with an air gun; S23: Place the die-cast blank after S21 into the lower die positioning area of ​​the hydraulic press. After it is clamped and stabilized, start the hydraulic press. The upper die shearing edge cooperates with the lower die to remove the sprue from the edge of the die-cast blank. After the upper die springs up, take out the die-cast part. The surface roughness of the cut surface is 4.2≤Ra≤6.3μm.

[0012] Through the above technical solution, in step S2, the slag bag on the edge of the die-cast blank is first removed, which removes excess waste material and makes the shape of the die-cast part closer to the final product form, reducing the amount of subsequent processing. The upper and lower dies of the hydraulic press are cleaned by air gun spraying to avoid impurities from damaging the die-cast blank during the stamping process and to ensure the surface quality of the die-cast part. The treated die-cast blank is placed in the positioning area of ​​the lower die of the hydraulic press. After it is clamped and stabilized, the hydraulic press is started. The upper die shearing edge cooperates with the lower die to remove the sprue on the edge of the die-cast blank. The surface roughness of the removed surface is controlled to be 4.2≤Ra≤6.3μm, which makes the sprue removal area flat and smooth, which is beneficial to subsequent processing and product assembly.

[0013] Furthermore, in step S3, the grinding wheel surface of the belt sander is perpendicular to the grinding surface of the die-cast part. The belt sander has a mesh size of 80-100 mesh, and the belt is made of alumina. The surface roughness of the grinding surface is 0.5μm≤Ra≤1.6μm.

[0014] Through the above technical solution, in step S3, the grinding wheel surface of the belt abrasive machine is perpendicular to the grinding surface of the die casting, ensuring that the texture direction of the grinding surface is consistent, reducing the problem of distortion and deformation caused by over-grinding. At the same time, the grinding wheel of the belt abrasive machine is 80-100 grit, and an alumina belt is used for grinding. The hardness of alumina matches that of the aluminum gearbox housing, which can make the surface roughness of the grinding surface 0.5μm≤Ra≤1.6μm. The slag pockets on the four edges of the die casting are ground more evenly, improving the grinding effect, effectively removing burrs and unevenness in the slag pockets, ensuring the dimensional accuracy and surface finish of the die casting, and improving the overall quality of the product.

[0015] Further, S4 includes the following steps: S41: Cleaning CNC machine tools by spraying with an air gun; S42: Place the die-cast part that has been polished in S3 into the clamping and positioning area of ​​the CNC machine tool. After the die-cast part is clamped by the pneumatic switch plate of the CNC machine tool, start the CNC machine tool to perform drilling to form a shaft hole in the first mounting groove of the die-cast part. S43: After drilling is completed, remove the machined die casting and inspect the shaft hole, wherein the diameter of the shaft hole is 22.5mm ± 0.1mm.

[0016] Through the above technical solution, step S41, cleaning the CNC machine tool with an air gun ensures the machine tool is in a clean working state, reducing the impact of impurities on drilling accuracy and guaranteeing the quality of subsequent drilling. Secondly, step S42 places the polished die-cast part into the clamping and positioning area, clamps it with a pneumatic switch plate, and then drills it, ensuring the stability of the die-cast part during the drilling process and forming a precise shaft hole in the first mounting groove. Finally, step S43 inspects the drilled shaft hole to ensure its diameter is 22.5mm ± 0.1mm, guaranteeing the dimensional accuracy of the hole position and facilitating subsequent use and assembly. Step S4 is set before product passivation or powder coating to avoid damage to the already treated surface caused by drilling, preventing coating damage, scratches, and other problems, thus ensuring good surface performance and stability of the product.

[0017] Further, S5 includes the following steps: S51: Use tools such as files to pre-treat the die castings processed in S4 to remove burrs and flash from the inside and outside of the die castings. S52: Place the die-cast parts processed in S51 on the hanger, and send the hanger into the shot blasting device. Multiple die-cast parts are spaced apart and do not contact each other.

[0018] S53: Start the shot blasting device, adjust the frequency converter to 30-31HZ, adjust the shot blasting time to 6 minutes, and the diameter range of the shot blasting sand is 0.3mm-0.5mm.

[0019] S54: After shot blasting, the die casting is subjected to secondary treatment using tools such as files to remove burrs and flash from the surface of the die casting.

[0020] Through the above technical solutions, in step S51, pre-treating the processed die-cast parts with tools such as files removes internal and external burrs and flash, providing a good foundation for subsequent shot blasting. In step S52, placing the pre-treated die-cast parts at intervals and without contact with each other on a hanger before feeding them into the shot blasting device ensures that each die-cast part surface receives uniform shot blasting treatment, avoiding mutual obstruction that affects the shot blasting effect and improving the surface quality of the die-cast parts. In step S53, during shot blasting, the frequency converter is adjusted to 30-31 Hz, the shot blasting time is 6 minutes, and the diameter range used is 0.3 mm. Shot blasting sand of 0.5 mm can achieve good surface roughness and cleanliness of die castings, providing better surface conditions for subsequent passivation treatment. This helps the passivation film to adhere more evenly and firmly, and also allows the powder to better bond with the die casting surface during subsequent powder spraying, improving the uniformity and adhesion of powder spraying and enhancing the overall quality of the product. The die castings after shot blasting in S54 undergo a secondary treatment to remove surface burrs and flash, which can further ensure that the die casting surface is free of burrs and flash, providing a good foundation for subsequent cleaning, passivation, powder spraying and other processes.

[0021] Further, S6 includes the following steps: S61: Place the die castings after deburring in S5 into the ultrasonic cleaning line, and the die castings should not block or stack each other. S62: The die-cast parts pass through the ultrasonic first cleaning tank, ultrasonic spray zone one, ultrasonic spray zone two, ultrasonic second cleaning tank and ultrasonic drying zone of the ultrasonic cleaning line in sequence. S63: Place the cleaned die-cast parts into the passivation frame, and lift the passivation frame into the passivation tank for passivation treatment; S64: After rinsing the passivated die-cast parts, place them in a baking device and dry them at 90-100℃ to obtain a semi-finished product of the gearbox housing.

[0022] Through the above technical solution, the deburred die-cast parts are placed in the ultrasonic cleaning line without obstructing or stacking each other, ensuring that all parts of the die-cast parts fully contact the cleaning medium and guaranteeing the cleaning effect. Furthermore, the die-cast parts sequentially pass through the first ultrasonic cleaning tank, the first ultrasonic spray zone, the second ultrasonic spray zone, the second ultrasonic cleaning tank, and the ultrasonic drying zone, enabling comprehensive cleaning of the die-cast parts and further facilitating subsequent passivation and improving the passivation effect. Furthermore, the spray solution in the ultrasonic spray zone 1 is composed of low-foaming isomeric alcohol polyoxyethylene ether, citric acid, benzotriazole and deionized water.

[0023] Through the above technical solution, the alkaline degreasing agent in the first ultrasonic cleaning tank can effectively remove oil stains from the surface of the die-cast parts, making the surface cleaner. Then, it enters the first ultrasonic spray zone. The spray liquid in the first ultrasonic spray zone is composed of low-foaming isomeric alcohol polyoxyethylene ether, citric acid, benzotriazole and deionized water, which can further remove residual impurities and slight oxide layers on the surface. While achieving secondary degreasing, it can also deeply penetrate the transition area between the curved surface and the flat surface of the product, thoroughly cleaning the surface of the outer shell and providing a good foundation for subsequent film formation.

[0024] Furthermore, the spray solution in the ultrasonic spray zone II is composed of γ-aminopropyltriethoxysilane solution, acetic acid, and deionized water; the passivating agent in the passivation tank is composed of cerium nitrate, fluorozirconic acid, hydrofluoric acid, and deionized water.

[0025] Using the above technical solution, the die-cast parts, after passing through the ultrasonic spray zone one, enter the ultrasonic spray zone two. The ultrasonic spray zone two consists of γ-aminopropyltriethoxysilane solution, acetic acid, and deionized water, which helps form a uniform protective film on the surface of the die-cast parts. This forms a monolayer on the surface of the die-cast parts, unifying the surface energy of the planar and curved surfaces, enhancing the surface corrosion resistance, and improving the adhesion between the surface and the passivation film. This lays the foundation for the uniform spreading of the subsequent passivation solution. Finally, rinsing and drying remove residual cleaning solution and moisture. After passing through the ultrasonic cleaning line, the die-cast parts are placed... Passivation is achieved by placing the aluminum in a passivation bath. The passivating agent forms a dense zirconium-cerium composite oxide film on the aluminum surface, resulting in a high-quality semi-finished product of the transmission gearbox housing. This ensures that the passivation film on the semi-finished product is uniform and consistent. Furthermore, the coating is less likely to peel off at the transition areas between curved and flat surfaces, as well as between curved and flat surfaces, after ultrasonic vibration. The pass rate is 100%, significantly reducing the defect rate. This solves the passivation problem in the transition area between curved and flat surfaces of the transmission gearbox housing, providing a good foundation for subsequent processing and use.

[0026] Further, S7 includes the following steps: S71: The semi-finished product of the gearbox housing is cleaned of surface impurities by a flame gun, wherein the flame gun moves at a speed of 150-200 mm / s; S72: The semi-finished transmission gearbox housing part after processing in S71 is moved into the powder spraying chamber. The spray gun is 200-300mm away from the semi-finished transmission gearbox housing part to achieve uniform powder spraying. The powder used is black sand texture powder, and the powder flow rate is controlled at 3.5-4.5g / s. S73: After the semi-finished gearbox housing part is powder coated, it is transferred to a baking device to achieve curing, thereby obtaining the finished gearbox housing part. The baking temperature range is 180℃-230℃.

[0027] The above technical solution utilizes a flame gun to clean the surface impurities of the semi-finished transmission gearbox housing component. This method precisely and comprehensively removes surface impurities, preventing residual impurities from affecting subsequent powder coating. Maintaining a distance of 200-300mm between the flame gun and the semi-finished component, using black textured powder, and controlling the powder flow rate to 3.5-4.5g / s ensures uniform powder adhesion to the surface of the semi-finished component due to the passivation layer and silane coupling agent. This prevents localized powder accumulation or exposed substrate, guaranteeing uniformity and consistency in powder coating. The powder-coated semi-finished component is then transferred to a baking device for curing within a temperature range of 180℃-230℃. This allows the powder to fully melt and firmly adhere to the surface of the housing component, further enhancing the uniformity and strength of the powder coating layer, improving the overall powder coating quality of the finished transmission gearbox housing component, and extending the product's service life.

[0028] Furthermore, the process steps of the manufacturing process also include S8, in which the finished gearbox housing part is provided with a plurality of first threaded holes, second threaded holes, third threaded holes and fourth threaded holes by drilling and threading. The first threaded hole is located at the end of the mounting base away from the shaft hole, the second threaded hole is located at the top of the mounting base, the third threaded hole is located at the top of the mounting post, and the fourth threaded hole is located on the surface of the bottom shell.

[0029] Through the above technical solution, the CNC machine tool can be used to drill and thread the finished gearbox housing, which can accurately produce the first, second, third and fourth threaded holes. These threaded holes of different specifications can meet a variety of installation and connection requirements, making the gearbox housing more flexible and adaptable when assembled with other components, enhancing the product's versatility and compatibility, improving the product's applicability in different application scenarios, and ensuring that the gearbox can operate stably and reliably.

[0030] In summary, this application includes at least the following beneficial technical effects: In step S1, the use of a cold chamber die-casting machine to inject molten aluminum into a mold to form a die-cast blank ensures the initial forming quality of the gearbox housing and guarantees basic structural integrity; Step S2, placing the die-cast blank into a hydraulic press to remove the sprue, makes the die-cast part more regular in shape, providing a good foundation for subsequent processing; Step S3, using a belt sander to grind the slag pockets around the die-cast part, makes the surface of the die-cast part smoother and reduces surface defects; Step S4, drilling using a CNC machine tool, accurately forms the required holes on the die-cast part, meeting assembly and usage requirements; Step S5, first pressing... Shot blasting and deburring of the castings make the surface of the die castings smoother, improving their surface quality and corrosion resistance. Step S6 involves ultrasonic cleaning, rinsing, passivation, rinsing, and drying, which effectively removes impurities and oil stains from the surface of the die castings. Simultaneously, a uniform and dense passivation film is formed on the surface of the outer casing, further laying the foundation for powder coating and curing in step S7, resulting in a semi-finished transmission gearbox outer casing. In step S7, the semi-finished transmission gearbox outer casing is powder-coated and baked for curing, improving the powder coating and curing effect, ultimately yielding the finished transmission gearbox outer casing. This solves the technical problem of uneven passivation in the transition area between the planar and curved structures of the transmission gearbox outer casing. Attached Figure Description

[0031] Figure 1 This is a first structural schematic diagram of the aluminum transmission gearbox housing component of the present invention; Figure 2 This is a second structural schematic diagram of the aluminum transmission gearbox housing component of the present invention.

[0032] Explanation of reference numerals in the attached figures: 1. Bottom shell; 2. Mounting base; 21. First mounting groove; 22. Second mounting groove; 23. Shaft hole; 3. Mounting post; 4. First threaded hole; 5. Second threaded hole; 6. Third threaded hole; 7. Fourth threaded hole. Detailed Implementation

[0033] The following is combined with Figure 1-2 The technical solutions in the embodiments of the present invention will be described in detail.

[0034] This invention provides a manufacturing process for an aluminum transmission gearbox housing, comprising the following steps: S1: The cold chamber die casting machine injects molten aluminum into the mold of the gearbox housing part for die casting to obtain a die casting blank.

[0035] Specifically, S1 includes the following steps: S11: Clean the mold cavity of the gearbox housing part, and spray the punch lubricant and release agent into the mold cavity in sequence; S12: Inject molten aluminum at 650℃±20℃ into the mold through the injection punch, and hold it under a pressure of 80-120MPa, wherein the injection filling time is 4-6s, the holding time is 10-15s, and the preheating temperature of the mold is 180-250℃; S13: After cooling, open the mold and take out the die-cast blank.

[0036] S2: Place the die-casting blank into the lower die positioning area of ​​the hydraulic press, and start the hydraulic press after it is clamped and stabilized to remove the sprue on the outside of the die-casting blank and obtain the die-casting part.

[0037] Specifically, S2 includes the following steps: S21: Remove slag from the edge of the die-cast blank; S22: Clean the impurities on the upper and lower molds of the hydraulic press by air gun spraying; S23: Place the die-cast blank treated in S21 into the positioning area of ​​the lower mold of the hydraulic press, and after it is clamped and stabilized, start the hydraulic press. The upper mold shearing edge cooperates with the lower mold to cut off the sprue on the edge of the die-cast blank. After the upper mold pops up, take out the die-cast part. The surface roughness of the cut surface is 4.2μm≤Ra≤6.3μm.

[0038] S3: The belt sander grinds the slag pockets around the perimeter of the die casting.

[0039] Specifically, in S3, the grinding wheel surface of the belt abrasive is perpendicular to the grinding surface of the die casting. The belt abrasive has a mesh size of 80-100, and the belt is made of alumina. The surface roughness is 0.5μm≤Ra≤1.6μm.

[0040] S4: Start the CNC machine tool to drill the first mounting slot of the die-cast part after S3 grinding.

[0041] Specifically, S4 includes the following steps: S41: Clean the CNC machine tool by spraying with an air gun; S42: Place the die-cast part polished in S3 into the clamping and positioning area of ​​the CNC machine tool, and after clamping the die-cast part by the pneumatic switch plate of the CNC machine tool, start the CNC machine tool to perform drilling, and drill a shaft hole 23 coaxial with the first mounting groove 21 in the first mounting groove 21 of the die-cast part; S43: After the drilling is completed, take out the processed die-cast part and check the shaft hole, wherein the diameter of the shaft hole is 22.5mm±0.1mm.

[0042] S5: Hang the die-cast part processed in S4 on the hanger, send the hanger into the shot blasting device, and after shot blasting, use tools to remove the burrs on the die-cast part.

[0043] Specifically, S5 includes the following steps: S51: Pre-treat the die-cast parts processed in S4 using tools such as files to remove burrs and sharp edges from the inside and outside of the die-cast parts; S52: Place the die-cast parts treated in S51 on a hanger, and send the hanger into the shot blasting device, wherein multiple die-cast parts are spaced apart and do not contact each other; S53: Start the shot blasting device, adjust the frequency converter to 30-31HZ, adjust the shot blasting time to 6-8 minutes, and the diameter of the shot blasting sand is in the range of 0.3mm-0.5mm; S54: After shot blasting, perform a secondary treatment on the die-cast parts using tools such as files to remove burrs and sharp edges from the surface of the die-cast parts.

[0044] In S51, firstly, the burrs and flash in the first mounting groove 21 of the die casting are removed by a pneumatic punching and flashing fixture; secondly, the operator removes the burrs and flash on the outside of the mounting base 2 of the die casting, the burrs and flash remaining after punching in the first mounting groove 21, the burrs and flash in the second mounting groove 22, the burrs and flash on the four periphery of the bottom shell 1, and the burrs and flash protruding on the orifice end of the mounting post 3 in sequence using a file.

[0045] S6: The die-cast parts that have been deburred in S5 are sequentially subjected to ultrasonic cleaning, rinsing, passivation treatment, rinsing and drying to obtain a semi-finished product of the gearbox housing. Specifically, S6 includes the following steps: S61: Place the die-cast parts, after deburring in S5, into the ultrasonic cleaning line, ensuring that the die-cast parts do not obstruct or overlap each other; S62: Pass the die-cast parts sequentially through the ultrasonic first cleaning tank, ultrasonic spray zone one, ultrasonic spray zone two, ultrasonic second cleaning tank, and ultrasonic drying zone of the ultrasonic cleaning line; S63: Place the cleaned die-cast parts into a passivation frame, lift the passivation frame, and move it into the passivation tank for passivation treatment; S64: After rinsing the passivated die-cast parts, place them in a baking device for drying at 90-100℃ to obtain a semi-finished product of the gearbox housing.

[0046] To further improve the cleaning effect on die-cast parts, the ultrasonic first cleaning tank contains an alkaline degreasing agent solution, which includes sodium hydroxide, sodium carbonate, sodium silicate, and polyoxyethylene ether surfactants. Preferably, the alkaline degreasing agent solution consists of 2%-3% sodium hydroxide, 4%-5% sodium carbonate, 2%-3% sodium silicate, 2%-2.5% polyoxyethylene octylphenol ether, and deionized water. The pH value of the ultrasonic first cleaning tank is controlled within the range of 10-12, the temperature within the range of 50-55℃, and the ultrasonic frequency within the range of 28-30kHz. The die-cast parts are cleaned in the ultrasonic first cleaning tank for 8 minutes. Sodium hydroxide and sodium carbonate provide degreasing ability, polyoxyethylene octylphenol ether enhances oil emulsification, and sodium silicate prevents secondary adhesion of dirt and has weak corrosion to the aluminum substrate. It can efficiently remove oil stains from die-cast parts and improve the cleaning effect of the ultrasonic first cleaning tank.

[0047] The spray solution in the ultrasonic spray zone one includes a low-foaming surfactant and a weakly acidic additive. Preferably, the spray solution in the ultrasonic spray zone one consists of 1%-2% by mass of low-foaming isomeric alcohol polyoxyethylene ether, 2%-3% by mass of citric acid, 0.3%-0.5% by mass of benzotriazole, and deionized water. The pH value of the spray solution in the ultrasonic spray zone one is controlled within the range of 5.5-6.5, the temperature range is 40-45℃, and the treatment time is 3-5 minutes. Among them, the low-foaming isomeric alcohol polyoxyethylene ether can reduce spray foam, citric acid neutralizes residual alkali, and benzotriazole forms a protective film to prevent over-corrosion spots from appearing on the aluminum surface, thereby further improving the cleaning effect.

[0048] The spray solution in the second ultrasonic spray zone includes γ-aminopropyltriethoxysilane (KH-550) and deionized water. Preferably, the spray solution in the second ultrasonic spray zone consists of 1.5%-2.5% γ-aminopropyltriethoxysilane solution, 0.3%-0.5% acetic acid, and the remainder deionized water. The pH value of the spray solution in the second ultrasonic spray zone is controlled within the range of 4.5-5.5, the temperature range is 40-45℃, and the treatment time is 3-5 minutes. In this process, the silane molecules in the γ-aminopropyltriethoxysilane solution hydrolyze and combine with the hydroxyl groups on the aluminum surface to form a uniform pre-film layer, providing a good adhesion substrate for the subsequent passivation film.

[0049] The second ultrasonic cleaning tank contains deionized water. The die-cast parts sequentially pass through the first ultrasonic cleaning tank, the first ultrasonic spray zone, the second ultrasonic spray zone, the second ultrasonic cleaning tank, and the ultrasonic drying zone of the ultrasonic cleaning line before entering the passivation tank. The coordinated steps of the ultrasonic cleaning line further improve the cleaning effect of the die-cast parts, enabling deep penetration into the transition areas between curved and flat surfaces and between curved and flat surfaces. This unifies the surface energy of the flat and curved surfaces of the die-cast parts, enhances the surface corrosion resistance, and improves the adhesion between the surface and the passivation film, providing a good foundation for the subsequent formation of the passivation film.

[0050] The passivating agent in the passivation tank consists of 0.5%-1.0% cerium nitrate, 0.8%-1.2% fluorozirconic acid, 0.3%-0.5% hydrofluoric acid, and deionized water. The passivation process is carried out at a pH of 4-4.5 and a temperature of 40-45℃, with the die-cast parts immersed for 6-8 minutes. The passivating agent forms a dense zirconium-cerium composite oxide film on the aluminum surface. After passivation, the parts are rinsed with deionized water for 2-5 minutes and then placed in a hot air circulating oven and dried at 90℃-100℃ for 30 minutes. This yields a semi-finished product of a gearbox housing with a clean surface and satisfactory corrosion resistance, laying the foundation for subsequent powder coating operations and further improving the adhesion of the powder coating.

[0051] S7: The semi-finished gearbox housing is powder-coated and baked to cure, thus obtaining the finished gearbox housing.

[0052] Specifically, S7 includes the following steps: S71: The semi-finished transmission gearbox housing part is cleaned of surface impurities by a blowtorch, wherein the blowtorch moving speed is 150-200mm / s; S72: The semi-finished transmission gearbox housing part after S71 is moved into the powder coating chamber, the blowtorch is 200-300mm away from the semi-finished transmission gearbox housing part to achieve uniform powder coating, wherein the powder coating uses black sandblasted powder, and the powder flow rate is controlled at 3.5-4.5g / s; S73: After the semi-finished transmission gearbox housing part is powder coated, it is moved into the baking device to achieve curing, thereby obtaining the finished transmission gearbox housing part, wherein the baking temperature range is 180℃-230℃.

[0053] S8: The finished gearbox housing has multiple first threaded holes 4, second threaded holes 5, third threaded holes 6 and fourth threaded holes 7 through drilling and threading. The first threaded hole 4 is located at the end of the mounting base 2 away from the shaft hole 23, the second threaded hole 5 is located at the top of the mounting base 2, the third threaded hole 6 is located at the top of the mounting post 3, and the fourth threaded hole 7 is located on the surface of the bottom shell 1.

[0054] Specifically, the first threaded hole 4 has a diameter of 6mm and a thread depth of 15mm; the second threaded hole 5 has a diameter of 4mm and a thread depth of 8mm; the third threaded hole 6 has a diameter of 5mm and a thread depth of 8mm; and the fourth threaded hole 7 is a through hole with a diameter of 4mm.

[0055] The following uses specific application examples and comparative models to demonstrate the effectiveness: Application Example 1 The finished transmission gearbox housing component in this application example is manufactured using the following process: Step 1: Clean the mold cavity of the gearbox housing component, and spray the punch lubricant and release agent into the mold cavity in sequence; inject molten aluminum at 650℃ into the mold through the injection punch, and hold it under a pressure of 100MPa, wherein the injection filling time is 6s, the holding time is 15s, and the mold preheating temperature is 180℃; after cooling, open the mold and remove the die-cast blank.

[0056] Step 2: Remove slag from the edges of the die-cast blank; clean the impurities on the upper and lower dies of the hydraulic press using an air gun; place the treated die-cast blank into the lower die positioning area of ​​the hydraulic press, and after it is clamped and stabilized, start the hydraulic press. The upper die shearing edge engages with the lower die to cut off the sprue from the edge of the die-cast blank. After the upper die springs up, remove the die-cast part. The surface roughness of the die-cast part is 4.5μm.

[0057] Step 3: The belt abrasive machine grinds the slag pockets around the four edges of the die casting. The grinding wheel of the belt abrasive machine is perpendicular to the grinding surface of the die casting. The belt abrasive machine has a mesh size of 80 and uses alumina belt. The surface roughness of the grinding surface of the die casting is 0.5μm.

[0058] Step 4: Clean the CNC machine tool with an air gun; place the polished die-cast part from S3 into the clamping and positioning area of ​​the CNC machine tool, and clamp the die-cast part with the pneumatic switch plate of the CNC machine tool. Then start the CNC machine tool to perform drilling. Drill a shaft hole coaxial with the first mounting groove in the first mounting groove of the die-cast part; after drilling is completed, take out the processed die-cast part and check the shaft hole, wherein the diameter of the shaft hole is 22.5mm.

[0059] Step 5: Pre-treat the die-cast parts after drilling using tools such as files to remove burrs and sharp edges from both the inside and outside of the die-cast parts; place the treated die-cast parts on a hanger and send the hanger into the shot blasting device; start the shot blasting device, adjust the frequency converter to 30HZ, adjust the shot blasting time to 6 minutes, and the diameter of the shot blasting sand to a range of 0.3mm-0.5mm; after shot blasting, use tools such as files to perform a secondary treatment on the die-cast parts to remove burrs and sharp edges from the surface of the die-cast parts.

[0060] Step Six: Place the die-cast parts processed in Step Five into the ultrasonic cleaning line, ensuring that the die-cast parts do not obstruct or overlap each other; the die-cast parts sequentially pass through the ultrasonic cleaning line's first ultrasonic cleaning tank, ultrasonic spray zone one, ultrasonic spray zone two, ultrasonic second cleaning tank, and ultrasonic drying zone; place the cleaned die-cast parts into the passivation frame, lift the passivation frame, and move it into the passivation tank for passivation treatment; after passivation, rinse the die-cast parts for 2 minutes, then place them in the baking device for drying at 100℃ to obtain the semi-finished product of the gearbox housing.

[0061] The alkaline degreasing agent solution in the ultrasonic first cleaning tank consists of 3% sodium hydroxide, 5% sodium carbonate, 2% sodium silicate, 2% polyoxyethylene octylphenol ether (Tesco Chemical (Hubei) Co., Ltd.), and deionized water. The pH value of the ultrasonic first cleaning tank is controlled within the range of 10, the temperature is 55℃, the ultrasonic frequency is 28kHz, and the cleaning time is 8 minutes.

[0062] The spray solution in the ultrasonic spray zone consists of 2% low-foaming isomeric alcohol polyoxyethylene ether, 2% citric acid, 0.3% benzotriazole, and deionized water. The pH value of the spray solution in the ultrasonic spray zone is controlled within the range of 5.5, the temperature is 40℃, and the treatment time is 5 minutes. The low-foaming isomeric alcohol polyoxyethylene ether used is C13 isomeric alcohol polyoxyethylene ether (IT1308, Jining Fangyu Chemical Co., Ltd.).

[0063] The spray solution in the second ultrasonic spray zone consists of a 1.5% (w / w) γ-aminopropyltriethoxysilane solution, a 0.5% (w / w) acetic acid solution, and deionized water. The pH value of the spray solution in the second ultrasonic spray zone is controlled within the range of 5.5, the temperature is 40℃, and the treatment time is 5 minutes. The γ-aminopropyltriethoxysilane solution is KH550 (Wuhan Smike Biotechnology Co., Ltd.).

[0064] The second ultrasonic cleaning tank contains deionized water, and the temperature in the ultrasonic drying zone is 100℃.

[0065] The passivating agent in the passivation tank consists of 0.5% cerium nitrate, 0.8% fluorozirconic acid, 0.3% hydrofluoric acid, and deionized water. The pH value ranges from 4.5, the temperature ranges from 40℃, and the immersion time for the die-cast parts is 6 minutes.

[0066] Step 7: The semi-finished transmission gearbox housing part is cleaned of surface impurities using a blowtorch, with the blowtorch moving at a speed of 150-200 mm / s. The treated semi-finished transmission gearbox housing part is then moved into a powder coating chamber, with the blowtorch 200-300 mm away from the semi-finished part to achieve uniform powder coating. Black textured powder is used, and the powder flow rate is controlled at 3.5-4.5 g / s. After powder coating, the semi-finished transmission gearbox housing part is moved into a baking device at a baking temperature of 200℃ for curing, resulting in the finished transmission gearbox housing part.

[0067] Comparative Example 1 The difference between the production process of Comparative Example 1 and Application Example 1 is that the spray solution in the ultrasonic spray zone 2 is composed of 1.5% by mass of γ-glycidyl etheroxypropyltrimethoxysilane solution, 0.5% by mass of acetic acid and deionized water.

[0068] Comparative Example 2 The difference between the production process of Comparative Example 2 and Application Example 1 is that the passivating agent in the passivation tank consists of 1.3% by mass of cerium nitrate, 0.3% by mass of hydrofluoric acid, and deionized water.

[0069] Comparative Example 3 The difference between the production process of Comparative Example 3 and Application Example 1 is that the passivating agent in the passivation tank consists of 1.3% by mass of fluorozirconic acid, 0.3% by mass of hydrofluoric acid, and deionized water.

[0070] Test and Results Analysis The finished transmission gearbox housing parts produced using the manufacturing processes of Application Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were subjected to adhesion tests, specifically referring to the cross-cut adhesion test GB / T9286-1998, which specifies the standard for adhesion where the material falls off after being cut into squares. The lower the grade, the better the adhesion.

[0071] The cross-cut adhesion test result of the transmission gearbox housing part produced in Comparative Example 1 is level 2, the cross-cut adhesion test result of the transmission gearbox housing part produced in Comparative Example 2 is level 1, the cross-cut adhesion test result of the transmission gearbox housing part produced in Comparative Example 2 is level 1, and the cross-cut adhesion test result of the transmission gearbox housing part produced in Application Example 1 is level 0. It can be seen that the powder adhesion of the transmission gearbox housing part produced by the process of this application is higher.

[0072] In addition, samples were randomly selected from the products in Application Example 1 and Comparative Examples 1-3, with 10 samples selected for each. The samples were treated with ultrasonic vibration at a frequency of 35 kHz for 30 minutes. Compared to Comparative Examples 1-3, the finished transmission gearbox housing parts produced in Application Example 1 showed that the coating at the transitions between curved and flat surfaces, as well as between curved and curved surfaces, was less prone to peeling after ultrasonic vibration, resulting in a 100% pass rate. In contrast, the transmission gearbox housing parts produced in Comparative Examples 1-3 showed coating peeling defects at the transitions between curved and flat surfaces, as well as between curved and curved surfaces, in 20-30% of the finished products, resulting in a product pass rate of only 70-80%.

[0073] This further illustrates that the combined action of γ-aminopropyltriethoxysilane and the passivating agent in the application example forms a uniform passivation layer on the surface of the housing component, effectively solving the problem of easy coating peeling in the transition areas between curved and flat surfaces and between curved surfaces on the surface structure of the housing component, thus improving the quality of the transmission gearbox housing component.

[0074] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A manufacturing process for an aluminum transmission gearbox housing, characterized in that: The process includes the following steps: S1: The cold chamber die casting machine injects molten aluminum into the mold of the gearbox housing part and die-casts it to obtain a die-cast blank; S2: Place the die-cast blank into the lower die positioning area of ​​the hydraulic press, and after clamping it stably, start the hydraulic press to remove the sprue on the outside of the die-cast blank to obtain the die-cast part; S3: The belt sander grinds the slag pockets around the perimeter of the die casting. S4: Start the CNC machine tool to drill the first mounting slot of the die-cast part after S3 grinding; S5: Hang the die-cast parts processed in S4 on the hanger, send the hanger into the shot blasting device, and after shot blasting, use tools to remove the burrs on the die-cast parts. S6: The die-cast parts that have been deburred in S5 are sequentially subjected to ultrasonic cleaning, rinsing, passivation treatment, rinsing and drying to obtain a semi-finished product of the gearbox housing. S7: The semi-finished transmission gearbox housing is powder-coated and baked to cure, thus obtaining the finished transmission gearbox housing.

2. The manufacturing process of an aluminum transmission gearbox housing according to claim 1, characterized in that: S1 includes the following steps: S11: Clean the mold cavity of the gearbox housing component, and spray punch lubricant and mold release agent into the mold cavity in sequence; S12: Molten aluminum at 650℃±20℃ is injected into the mold through an injection punch and held under a pressure of 80-120MPa. The injection filling time is 4-6s, the holding time is 10-15s, and the mold preheating temperature is 180-250℃. S13: After cooling, open the mold and remove the die-cast blank.

3. The manufacturing process of an aluminum transmission gearbox housing according to claim 1, characterized in that: S2 includes the following steps: S21: Remove slag pockets from the edges of the die-cast blank; S22: Cleaning impurities on the upper and lower molds of the hydraulic press by spraying with an air gun; S23: Place the die-cast blank after S21 into the lower die positioning area of ​​the hydraulic press. After it is clamped and stabilized, start the hydraulic press. The upper die shearing edge cooperates with the lower die to remove the sprue from the edge of the die-cast blank. After the upper die springs up, take out the die-cast part. The surface roughness of the cut surface is 4.2μm≤Ra≤6.3μm.

4. The manufacturing process of an aluminum transmission gearbox housing according to claim 1, characterized in that: In step S3, the grinding wheel surface of the belt sander is perpendicular to the grinding surface of the die-cast part. The belt sander has a mesh size of 80-100 mesh, and the belt is made of alumina. The surface roughness of the grinding surface is 0.5μm≤Ra≤1.6μm.

5. The manufacturing process of an aluminum transmission gearbox housing according to claim 1, characterized in that: S4 includes the following steps: S41: Cleaning CNC machine tools by spraying with an air gun; S42: Place the die-cast part after grinding in S3 into the clamping and positioning area of ​​the CNC machine tool. After the die-cast part is clamped by the pneumatic switch plate of the CNC machine tool, start the CNC machine tool to perform drilling. Drill a shaft hole coaxial with the first mounting groove in the first mounting groove of the die-cast part. S43: After drilling is completed, remove the machined die casting and inspect the shaft hole, wherein the diameter of the shaft hole is 22.5mm ± 0.1mm.

6. The manufacturing process of an aluminum transmission gearbox housing according to claim 1, characterized in that: S5 includes the following steps: S51: Use tools such as files to pre-treat the die castings processed in S4 to remove burrs and flash from the inside and outside of the die castings. S52: Place the die-cast parts processed in S51 on the hanger, and send the hanger into the shot blasting device. Multiple die-cast parts are spaced apart and do not contact each other. S53: Start the shot blasting device, adjust the frequency converter to 30-31HZ, adjust the shot blasting time to 6-8 minutes, and the diameter of the shot blasting sand is 0.3mm-0.5mm; S54: After shot blasting, the die casting is subjected to secondary treatment using tools such as files to remove burrs and flash from the surface of the die casting.

7. The manufacturing process of an aluminum transmission gearbox housing according to claim 1, characterized in that: S6 includes the following steps: S61: Place the die castings after deburring in S5 into the ultrasonic cleaning line, and the die castings should not block or stack each other. S62: The die-cast parts pass through the ultrasonic first cleaning tank, ultrasonic spray zone one, ultrasonic spray zone two, ultrasonic second cleaning tank and ultrasonic drying zone of the ultrasonic cleaning line in sequence. S63: Place the cleaned die-cast parts into the passivation frame, and lift the passivation frame into the passivation tank for passivation treatment; S64: After rinsing the passivated die-cast parts, place them in a baking device and dry them at 90-100℃ to obtain a semi-finished product of the gearbox housing.

8. The manufacturing process of an aluminum transmission gearbox housing according to claim 1, characterized in that: S7 includes the following steps: S71: The semi-finished product of the gearbox housing is cleaned of surface impurities by a flame gun, wherein the flame gun moves at a speed of 150-200 mm / s; S72: The semi-finished transmission gearbox housing part after processing in S71 is moved into the powder spraying chamber. The spray gun is 200-300mm away from the semi-finished transmission gearbox housing part to achieve uniform powder spraying. The powder used is black sand texture powder, and the powder flow rate is controlled at 3.5-4.5g / s. S73: After the semi-finished gearbox housing part is powder coated, it is transferred to a baking device to achieve curing, thereby obtaining the finished gearbox housing part. The baking temperature range is 180℃-230℃.

9. The manufacturing process of an aluminum transmission gearbox housing according to claim 7, characterized in that: The spray solution in the ultrasonic spray zone 1 is composed of low-foaming isomeric alcohol polyoxyethylene ether, citric acid, benzotriazole and deionized water.

10. The manufacturing process of an aluminum transmission gearbox housing according to claim 7, characterized in that: The spray solution in the ultrasonic spray zone II consists of γ-aminopropyltriethoxysilane solution, acetic acid, and deionized water, while the passivation agent in the passivation tank consists of cerium nitrate, fluorozirconic acid, hydrofluoric acid, and deionized water.

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