Batch production process of SBW gear

Abstract

The invention discloses a batch production process of SBW gears, and relates to the technical field of fine blanking processes, and the process comprises the following steps: transformation of a hydraulic system of a fine blanking machine, deep drawing forming of a gear appearance wrinkle part, full-bright stamping of a tooth shape, composite forming of double-sided bulges, design of an inner hole finish machining tool and optimization of a heat treatment process. Double-face protrusion forming is achieved through a composite progressive die, a tooth-shaped full-bright shear face is completed in combination with a special deep drawing die and a fine blanking technology, and the machining precision of an inner hole is guaranteed through a profiling clamping tool. According to the technology, a cold forming technology is adopted to replace traditional hot working, the material utilization rate is increased to 85% or above, the product precision reaches the tooth profile precision + / -0.03 mm, the coaxiality is smaller than 0.04 mm, the hardness HRC is 57-65, the production process is energy-saving and environmentally friendly, and the technology is suitable for the batch production requirement in the field of automobile intellectualization.

Description

Technical Field

[0001] The invention relates to the technical field of fine blanking technology, and in particular to a batch production process of SBW gears. Background Art

[0002] SBW gears are the core transmission components of the electronic shift-by-wire system, and their performance directly affects the smoothness of shifting and the life of the system. The current mainstream production processes include hot forging and cutting, but there are the following defects: Low material utilization rate: The material utilization rate of hot forging process is only 50%-60%, and cutting process produces a lot of waste chips; Insufficient precision: deformation after hot forging and heat treatment leads to fluctuations in tooth profile accuracy (more than ±0.05mm) and coaxiality out of tolerance (>0.06mm); High energy consumption: Hot forging requires high temperature heating, and energy consumption accounts for more than 30% of production costs; Poor surface quality: The roughness of the cutting tooth surface Ra is greater than 1.6μm, and the proportion of bright band is less than 90%, which reduces the fatigue life of the gear.

[0003] The prior art proposes to use fine blanking technology to improve the tooth profile accuracy, but does not solve the problems of double-sided protrusion composite forming and inner hole coaxiality control, and does not optimize the mold life. Therefore, there is an urgent need for a SBW gear production process that takes into account high precision, high material utilization and low energy consumption. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a mass production process for SBW gears, which can realize the forming of the special structure of SBW gears through an efficient stamping process, meet the performance requirements of the product, and take into account the production process requirements of high precision, high material utilization and low energy consumption.

[0005] One of the above-mentioned invention objects of the present invention is achieved through the following technical solutions: A batch production process of SBW gears, characterized in that it includes the following steps: S1: Raw material preparation: Select high-quality plates that meet specific mechanical property requirements, use a metallographic analyzer to test the raw material microstructure to ensure that it meets the standards, and use cutting equipment to cut according to the SBW gear size specifications, and control the cutting size deviation within ±0.2mm; S2: Design and manufacturing of stamping dies: Based on the precise tooth shape and structure of the SBW gear, CAE analysis is used to optimize the drawing coefficient and perform three-dimensional modeling of the stamping die to ensure that the dimensional accuracy of the die cavity and core is within ±[3-6]μm; S3: Deep drawing of the wrinkled part of the gear shape: Based on CAE analysis, the drawing coefficient and die structure are optimized, and the outer edge wrinkles of the gear are formed step by step through a special drawing die. The radius of the male and female dies is controlled to be ≤0.2mm, and the drawing clearance is 8%-10% of the plate thickness; S4: Tooth profile full bright stamping: Using fine stamping die, on the basis of the original three-way force of main blanking force, blank holding force and anti-pushing force of fine stamping machine, the fourth hydraulic oil circuit and the fifth hydraulic oil circuit are added to meet the multi-force system requirements of compound fine stamping die, and the die gap is set to 0.5%-1% of the plate thickness, the blank holding force is 20%-30% of the blanking force, and the anti-pushing force is 10%-15% of the blanking force, so as to achieve a bright zone ratio of ≥95% on the tooth shear surface; S5: Double-sided convex composite forming: The plate is sequentially extruded, flattened, and reversely extruded through a composite progressive die, with the extrusion height controlled to be 1.2-1.5 times the plate thickness, and the flattening strength to be 80%-90% of the material yield strength; S6: Inner hole finishing: Use contour clamping fixture, the clamping surface is contour matched with the tooth profile, the clamping force accuracy is ≤0.5N, and the airtight detection device is used to ensure the clamping coaxiality is <0.04mm; S7: Heat treatment process: Carburizing and quenching or gas nitriding treatment is performed on the gears, the carburizing layer depth is 0.2-0.4mm, the compound layer thickness is 0.007-0.02mm, and the deformation after heat treatment is less than 0.05mm.

[0006] On the basis of the original hydraulic system, by adding a hydraulic oil circuit, the output of the fourth hydraulic pressure and the fifth hydraulic pressure is realized, so that the hydraulic system of the fine blanking machine can provide the fourth hydraulic pressure and the fifth hydraulic pressure for the hydraulic cylinder in the fine blanking die, meeting the requirements of the compound fine blanking die for multiple force systems.

[0007] When designing the mold, we rely on CAE analysis software to analyze the shape deformation, stress distribution, fracture risk, etc. during the deep drawing process. Through the analysis results, we optimize the stamping process and mold structure to make the mold debugging process more economical and efficient, which can greatly save the cost of mold testing and shorten the development cycle of stamping molds.

[0008] The fine blanking process can achieve full brightness of the stamping shear surface. When designing the fine blanking process, the corresponding blanking clearance, die edge shape, fine blanking force and other fine blanking parameters are designed according to the shape contour of the product.

[0009] The three-dimensional forming of the plate is achieved through the processes of extrusion-flattening-reverse extrusion, replacing the hot forming technology-hot forging or casting. The products produced have high precision and high material utilization rate. The cold forming technology replaces the hot forming technology, which can reduce energy consumption and be more energy-saving and environmentally friendly.

[0010] The use of special tooling for contour clamping can ensure that the tooth shape is not deformed, there is no indentation on the tooth surface, and the accuracy of the inner hole finishing is stable during the fine machining of the inner hole. An airtight inspection device is added to the tooling to prevent abnormal operations such as biased clamping and incorrect clamping position.

[0011] The heat treatment process can greatly enhance the performance stability of gears and meet the requirements of use.

[0012] Specifically, in step S1, the utilization rate of the fine blanking machine is ≥85%, and the output pressure range of the fourth hydraulic oil circuit and the fifth hydraulic oil circuit is 10-20 MPa.

[0013] Specifically, the corner radius of the concave die of the drawing die in step S2 is R≤0.2mm, the corner radius of the punch is R≤0.15mm, the number of drawing times is determined by CAE simulation, and the fracture risk coefficient is ≤1.2.

[0014] Specifically, the contoured clamping tooling in step S5 is made of cemented carbide, with a surface roughness Ra≤0.4 μm and an airtight detection pressure deviation≤5%.

[0015] In summary, the beneficial technical effects of the present invention are: 1. Through the combination of compound progressive die and fine blanking technology, the tooth profile is fully bright sheared (bright band accounts for ≥95%), the surface roughness Ra≤0.4μm, and the fatigue life of the gear is significantly improved; the cold forming process replaces the traditional hot processing, the material utilization rate is increased from 50%-60% of the traditional process to more than 85%, and the energy consumption of a single piece is reduced by 40%; 2. Use contoured clamping fixtures and airtight detection devices to ensure that the coaxiality of the inner hole processing is less than 0.04mm, avoiding the loss of precision caused by clamping deviation; optimize the heat treatment process parameters, the carburizing layer depth is 0.2-0.4mm, the deformation after heat treatment is less than 0.05mm, and the hardness reaches HRC57-65, meeting the high durability requirements of the automotive wire-controlled shift system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the metallographic diagram of existing domestic products; Figure 2 It is a metallographic diagram of the process product of the present invention. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0018] A batch production process of SBW gears comprises the following steps: S1: Raw material preparation: Select high-quality plates that meet specific mechanical property requirements, use a metallographic analyzer to test the raw material microstructure to ensure that it meets the standards, and use cutting equipment to cut according to the SBW gear size specifications, and control the cutting size deviation within ±0.2mm; S2: Design and manufacturing of stamping dies: Based on the precise tooth shape and structure of the SBW gear, CAE analysis is used to optimize the drawing coefficient and perform three-dimensional modeling of the stamping die to ensure that the dimensional accuracy of the die cavity and core is within ±[3-6]μm; S3: Deep drawing of the wrinkled part of the gear shape: Based on CAE analysis, the drawing coefficient and die structure are optimized, and the outer edge wrinkles of the gear are formed step by step through a special drawing die. The radius of the male and female dies is controlled to be ≤0.2mm, and the drawing clearance is 8%-10% of the plate thickness; S4: Tooth profile full bright stamping: Using fine stamping die, on the basis of the original three-way force of main blanking force, blank holding force and anti-pushing force of fine stamping machine, the fourth hydraulic oil circuit and the fifth hydraulic oil circuit are added to meet the multi-force system requirements of compound fine stamping die, and the die gap is set to 0.5%-1% of the plate thickness, the blank holding force is 20%-30% of the blanking force, and the anti-pushing force is 10%-15% of the blanking force, so as to achieve a bright zone ratio of ≥95% on the tooth shear surface; S5: Double-sided convex composite forming: The plate is sequentially extruded, flattened, and reversely extruded through a composite progressive die, with the extrusion height controlled to be 1.2-1.5 times the plate thickness, and the flattening strength to be 80%-90% of the material yield strength; S6: Inner hole finishing: Use contour clamping fixture, the clamping surface is contour matched with the tooth profile, the clamping force accuracy is ≤0.5N, and the airtight detection device is used to ensure the clamping coaxiality is <0.04mm; S7: Heat treatment process: Carburizing and quenching or gas nitriding treatment is performed on the gears, the carburizing layer depth is 0.2-0.4mm, the compound layer thickness is 0.007-0.02mm, and the deformation after heat treatment is less than 0.05mm.

[0019] Specifically, in step S1, the utilization rate of the fine blanking machine is ≥85%, and the output pressure range of the fourth and fifth hydraulic oil circuits is 10-20 MPa.

[0020] Specifically, the corner radius of the concave die of the drawing die in step S2 is R≤0.2mm, the corner radius of the punch is R≤0.15mm, the number of drawing times is determined by CAE simulation, and the fracture risk coefficient is ≤1.2.

[0021] Specifically, the contoured clamping tooling in step S5 is made of cemented carbide, with a surface roughness Ra≤0.4 μm and an airtight detection pressure deviation≤5%.

[0022] Reference Figure 1 and Figure 2, Figure 1 This is the metallographic diagram of existing domestic products. Figure 2 This is the metallographic diagram of the product of the process of the present invention. During the high-speed precision blanking process of the metal sheet, the three-dimensional compressive stress state is used to suppress the generation of material cracks. At the same time, the rapid shear deformation causes the austenite grains to undergo violent plastic flow, resulting in a significant increase in dislocation density. Figure 1 As shown, the austenite grains formed by the fine blanking process of the present invention are small in size and arranged in a direction, and the substructure in the shear band is obvious. This high-density dislocation structure effectively hinders the migration of austenite grain boundaries and inhibits the recrystallization process.

[0023] In contrast, hot forging processes involve high temperature plastic deformation ( Figure 2 ), the austenite structure shows typical dynamic recrystallization characteristics. Since the deformation temperature is higher than the recrystallization temperature, the grains achieve structural homogenization through the nucleation-growth mechanism to form equiaxed austenite grains. However, the higher thermal activation energy during hot forging causes some grains to grow abnormally, and the grain boundary straightening trend is obvious, such as Figure 2 Coarse austenite grains of 100-150 μm can be seen in some local areas.

[0024] By comparison, it can be seen that the ultrafine austenite structure (average grain size 2-5μm) obtained by the fine blanking process of the present invention through severe shear deformation at room temperature has a grain boundary strengthening effect that increases the material hardness by about 30%, and the texture orientation formed by multi-directional compressive stress improves the wear resistance; while the hot forging process can obtain uniform equiaxed grains (average size 20-50μm), but the coarse grains cause its fatigue resistance to be 15%-20% lower than that of the fine blanking parts. The fine blanking parts produced by the fine blanking process of the present invention are more suitable for high-precision and high-wear-resistant working conditions, meeting the high durability requirements of the automotive wire-controlled shift system.

[0025] The following is a comparison of parameters between the products using the process of the present invention and foreign products and existing domestic products.

[0026] It can be seen from the above table that the process products of the present invention reach or exceed foreign products in key indicators such as tooth profile accuracy (IT6), surface roughness (Ra0.4), coaxiality (<0.04mm), etc., and are significantly better than existing domestic products.

[0027] The following is a comparison of parameters between the process of the present invention and the domestic traditional process:

[0028] It can be seen from the above table that the traditional process is relatively simple in equipment pressure and mold design, resulting in low efficiency and insufficient precision. The present invention achieves higher precision (relative flattening amount 65%) and fewer processes (flattening once) through a composite mold structure, multi-force system equipment and smaller mold gap.

[0029] The working principle of this embodiment is: on the basis of the original hydraulic system, by adding a hydraulic oil circuit, the output of the fourth hydraulic pressure and the fifth hydraulic pressure is realized, so that the hydraulic system of the fine punching machine can provide the fourth hydraulic pressure and the fifth hydraulic pressure for the hydraulic cylinder in the fine punching mold, thereby meeting the requirements of the composite fine punching mold for multiple force systems.

[0030] When designing the mold, we rely on CAE analysis software to analyze the shape deformation, stress distribution, fracture risk, etc. during the deep drawing process. Through the analysis results, we optimize the stamping process and mold structure to make the mold debugging process more economical and efficient, which can greatly save the cost of mold testing and shorten the development cycle of stamping molds.

[0031] The fine blanking process can achieve full brightness of the stamping shear surface. When designing the fine blanking process, the corresponding blanking clearance, die edge shape, fine blanking force and other fine blanking parameters are designed according to the shape contour of the product.

[0032] The three-dimensional forming of the plate is achieved through the processes of extrusion-flattening-reverse extrusion, replacing the hot forming technology-hot forging or casting. The products produced have high precision and high material utilization rate. The cold forming technology replaces the hot forming technology, which can reduce energy consumption and be more energy-saving and environmentally friendly.

[0033] The use of special tooling for contour clamping can ensure that the tooth shape is not deformed, there is no indentation on the tooth surface, and the accuracy of the inner hole finishing is stable during the fine machining of the inner hole. An airtight inspection device is added to the tooling to prevent abnormal operations such as biased clamping and incorrect clamping position.

[0034] The heat treatment process can greatly enhance the performance stability of gears and meet the requirements of use.

[0035] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A batch production process of SBW gears, characterized by: The following steps are included: S1: Raw material preparation: Select high-quality plates that meet specific mechanical property requirements, use a metallographic analyzer to test the raw material microstructure to ensure that it meets the standards, and use cutting equipment to cut according to the SBW gear size specifications, and control the cutting size deviation within ±0.2mm; S2: Design and manufacturing of stamping dies: Based on the precise tooth shape and structure of the SBW gear, CAE analysis is used to optimize the drawing coefficient and perform three-dimensional modeling of the stamping die to ensure that the dimensional accuracy of the die cavity and core is within ±[3-6]μm; S3: Deep drawing of the wrinkled part of the gear shape: Based on CAE analysis, the drawing coefficient and die structure are optimized, and the outer edge wrinkles of the gear are formed step by step through a special drawing die. The radius of the male and female dies is controlled to be ≤0.2mm, and the drawing clearance is 8%-10% of the plate thickness; S4: Tooth profile full bright stamping: Using fine stamping die, on the basis of the original three-way force of main blanking force, blank holding force and anti-pushing force of fine stamping machine, the fourth hydraulic oil circuit and the fifth hydraulic oil circuit are added to meet the multi-force system requirements of compound fine stamping die, and the die gap is set to 0.5%-1% of the plate thickness, the blank holding force is 20%-30% of the blanking force, and the anti-pushing force is 10%-15% of the blanking force, so as to achieve a bright zone ratio of ≥95% on the tooth shear surface; S5: Double-sided convex composite forming: The plate is sequentially extruded, flattened, and reversely extruded through a composite progressive die, with the extrusion height controlled to be 1.2-1.5 times the plate thickness, and the flattening strength to be 80%-90% of the material yield strength; S6: Inner hole finishing: Use contour clamping fixture, the clamping surface is contour matched with the tooth profile, the clamping force accuracy is ≤0.5N, and the airtight detection device is used to ensure the clamping coaxiality is <0.04mm; S7: Heat treatment process: Carburizing and quenching or gas nitriding treatment is performed on the gears, the carburizing layer depth is 0.2-0.4mm, the compound layer thickness is 0.007-0.02mm, and the deformation after heat treatment is less than 0.05mm.

2. A batch production process of SBW gears according to claim 1, characterized in that: In step S1, the utilization rate of the fine blanking machine is ≥85%, and the output pressure range of the fourth and fifth hydraulic oil circuits is 10-20 MPa.

3. The mass production process of SBW gears according to claim 1, characterized in that: The corner radius of the concave die of the drawing die in step S2 is R≤0.2mm, the corner radius of the punch is R≤0.15mm, the number of drawing times is determined by CAE simulation, and the fracture risk coefficient is ≤1.

2.

4. The mass production process of SBW gears according to claim 1, characterized in that: The contoured clamping fixture in step S5 is made of cemented carbide, with a surface roughness Ra≤0.4μm and an airtight detection pressure deviation≤5%.

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