Rotor cup housing bearing chamber bearing hole periphery R angle forming local material thickening process

Abstract

The application discloses a kind of rotor cup machine shell bearing chamber bearing hole periphery R angle forming local material thickening process, by pre-stretching, main stretching, pre-punching bearing hole, back to mound and shrinkage back mound, final stretching finishing these six steps are completed.The application process optimizes the distribution regulation and control of metal flow in the plastic deformation process of stretching forming material and controls the quantitative flow of material, realizes the integral thickening of the material in the bearing chamber area, realizes the accurate control of material flow, thereby realizes the directional thickening of local material, and the shell product prepared is locally increased in thickness by more than one time of the original material thickness at the bearing hole periphery R angle of bearing chamber, while ensuring that the wall thickness of bearing chamber is only slightly thinned, to ensure that the rotor cup machine shell is completed and the forming quality is improved, and the product reaches higher mechanical strength, dimensional accuracy and surface quality.

Description

Technical Field

[0001] This invention relates to the manufacture of rotary motor housings, and in particular to a process for locally thickening the material of rotor cup housings. Background Technology

[0002] In rotating electric motor design, the rotor cup housing, as a key component that bears the bearings and transmits torque, directly affects the operational stability and service life of the motor due to the strength and precision of the radius (R) stretch forming of its bearing housing. Traditional manufacturing processes for the rotor cup housing bearing housing typically employ integral forging to increase the material thickness in certain areas of the housing, or machine local shaft parts of the bearing housing and then weld them to the housing to achieve localized material thickening, thereby ensuring the strength and service life of the rotor cup.

[0003] In recent years, research on rotor system performance optimization has shown that precise control of material mechanical properties has a significant effect on suppressing torque pulsation and reducing vibration (i.e., increasing the thickness of local materials in the housing and ensuring the uniformity of thickness can guarantee the stable operation and service life of rotating motors). Against this backdrop, directional thickening of the radius (R-angle) material around the bearing housing has become an effective way to improve the fatigue resistance of components. While the technology of thickening and stretching the radius material using stamping and integral forming can effectively improve the operational stability and load-bearing capacity of rotating machinery, it also faces defects such as uneven material flow, susceptibility to cracking and deformation, which affect product quality and performance.

[0004] As attached Figure 1 As shown, in conventional stretch forming processes, the thickness of the flange plane is typically increased. This is achieved by setting the stretch gap and the radius (R) angles of the punch and die to ensure directional material flow until the flange plane is thickened. Usually, the material thickness of the flange plane increases, but the bearing housing wall thickness decreases. (See attached diagram) Figure 2 As shown, bearing housing thickening technology typically employs a stacked material stretching technique. This technique can effectively increase the wall thickness of the bearing housing. However, due to the stacked structure, the bearing housing wall is not a single, integral structure, and gaps exist. Therefore, this process is suitable for applications involving small motor housings with low torque and low speed. Furthermore, due to the limitations of the process structure, the outer layer material becomes significantly thinner. Although it involves the superposition of two layers of material thickness, it cannot achieve a localized doubling of the material thickness. It is evident that the above-mentioned stamping technology has many drawbacks and limitations in the process of localized material stretching and thickening. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a process for locally thickening the material around the R-angle of the bearing hole in the rotor cup housing bearing chamber, thereby increasing the material thickness of the housing bearing chamber at the R-angle around the bearing hole while ensuring limited reduction in the wall thickness of the bearing chamber, thus guaranteeing the structural strength, dimensional accuracy, and surface quality of the housing product.

[0006] Technical solution: A process for locally thickening the R-angle around the bearing hole of a rotor cup housing bearing chamber, comprising the following steps:

[0007] S10: Pre-stretching;

[0008] S101: A circular flat plate is stretched to form a first cylinder with a tapered top and an open bottom; the inner diameter of the upper and lower sides of the tapered part is R20, and the outer diameter of the bottom opening part is R12.

[0009] S102: The top middle of the first cylinder is stretched inward to form a second cylinder. The inner diameter of the bottom R-angle of the second cylinder is R8, the inner diameter of the R-angle of the transition part between the top of the second cylinder and the first cylinder is R10, the inner diameter of the R-angle of the lower side of the tapered part at the top of the first cylinder is R16, and the outer diameter of the R-angle of the opening part at the bottom of the first cylinder is R12.

[0010] S20: Main tension;

[0011] While keeping the outer diameter of the first cylinder constant, the second cylinder continues to be stretched inward in multiple stages, gradually reducing its inner and outer diameters. The inner diameter of the top R-angle of the second cylinder formed after the first reverse stretch is R8, the outer diameter is R11.5, and the height of the second cylinder remains unchanged in subsequent reverse stretches. However, the inner diameter of the bottom R-angle of the second cylinder is gradually reduced from R8 to R5, thereby ensuring the uniformity of the wall thickness of the second cylinder without increasing the stretching height. The inner diameter R8 of the top R-angle of the second cylinder serves as the reference point for subsequent local material thickening.

[0012] S30: Pre-punched bearing bore;

[0013] A round hole is punched in the middle of the bottom of the second cylinder as a pre-punch hole for forming the bearing chamber. At the same time, the top plane of the first cylinder is shaped so that part of the material flowing back to the top surface of the first cylinder in S20 is squeezed to the R-corner of the bottom opening of the first cylinder through the shaping.

[0014] S40: Bearing hole flanging and stretching after flanging;

[0015] S401: While straightening the bottom plane of the round hole, the outer diameter and inner diameter of the second cylinder are reduced and the height is shortened. The top of the second cylinder is formed with a concave mold to form an inner diameter of R8. The material flow causes the outer diameter to shrink from R11.5 to R8, realizing the first thickening of the R angle around the bearing hole.

[0016] S402: Continue to stretch the second cylinder to reduce its outer and inner diameters and increase its height. The top of the second cylinder is formed with a die to create an inner diameter of R8. The material flow causes the outer diameter to shrink from R8 to R5, thus achieving a second thickening of the R-angle around the bearing hole.

[0017] S50: Back pier and narrow hole back pier;

[0018] S501: While keeping the outer and inner diameters of the second cylinder unchanged, the height of the second cylinder is increased, and the inner diameter of the R-angle of the top of the second cylinder is formed by a concave die. The material flow causes the outer diameter to shrink from R5 to R1.5, thus achieving the third thickening of the R-angle around the bearing hole.

[0019] S502: Continue to increase the height of the second cylinder and reduce the outer and inner diameters of the second cylinder. The top of the second cylinder is formed with a concave die to form an inner diameter of R8. The material flow causes the outer diameter to shrink from R1.5 to R1, thus achieving the fourth thickening of the R angle around the bearing hole.

[0020] S60: Final pull finishing;

[0021] The product undergoes final stretching and finishing to shape the outer diameter of the first cylinder, the height of the second cylinder, and the top plane of the first cylinder to conform to the design dimensions.

[0022] Furthermore, in S101, the thickness of the circular flat plate is 3.5mm, and it is made of DC04 cold-rolled plate, which is stretched with a tensile coefficient of 0.68 and a stretching gap of 1.1 times the material thickness.

[0023] Furthermore, in S10 and S20, the R-angle is set by the mold to ensure the inner and outer diameters of the R-angle formed by the product.

[0024] Furthermore, in S20, stretching is performed with a tensile coefficient of 0.8 and a stretching gap of 1.1 times the material thickness.

[0025] Furthermore, in S20, an upper mold push block with a contoured surface is provided, and the contoured surface acts on the top plane of the first cylinder.

[0026] Furthermore, in both S401 and S402, a height limiting device is installed inside the mold to ensure the forming height of the second cylinder.

[0027] Furthermore, in S60, S601 performs final stretching on the product, stretching the outer diameter of the first cylinder and the height of the second cylinder to meet the design dimensions. During the stretching process, the unevenness caused by some material flowing back to the top surface of the first cylinder in S50 is shaped into a flat surface. S602 performs fine finishing on the product, so that the outer and inner diameters of the first cylinder, the top plane of the first cylinder, and the outer and inner diameters of the second cylinder meet the design dimensions of the housing product.

[0028] Furthermore, after S60 is completed, the edges are trimmed, chamfered, and deburred to complete the shaping of other aspects of the product.

[0029] Beneficial effects: The process optimization of this invention optimizes the distribution and control of metal flow during the plastic deformation of the material in stretch forming, and controls the quantitative flow of the material to achieve integrated thickening of the material in the bearing chamber area. It achieves precise control of material flow, thereby achieving localized directional thickening of the material. The resulting housing product has a local material thickness at the R-angle around the bearing hole in the bearing chamber that is more than doubled compared to the original material thickness. At the same time, it ensures that the wall thickness of the bearing chamber is only slightly reduced, so as to ensure the completion of the rotor cup housing and improve the forming quality. The product achieves higher mechanical strength, dimensional accuracy, and surface quality. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the thickening of the flange surface of the housing in a conventional stretch forming process.

[0031] Figure 2 This is a schematic diagram of the thickening of the bearing chamber wall in the stacking and stretching technology;

[0032] Figure 3 A schematic diagram of the structure at the R-angle around the bearing hole in the bearing chamber opening of the housing product of this application, using conventional stretch forming process.

[0033] Figure 4 This is a schematic diagram of the structure of the housing product of this application, which uses the extrusion process of adding pressure ribs to the inner R-angle at the R-angle of the bearing hole at the bearing chamber opening;

[0034] Figure 5 This is a schematic diagram of the molding process of the casing product under the process of the present invention;

[0035] Figure 6 This is a schematic diagram of the mold structure for process S201 (mold closed).

[0036] Figure 7 This is a schematic diagram of the mold structure for process S204 (in the mold-open state).

[0037] Figure 8 This is a schematic diagram of the S30 process for punching a circular hole in the middle of the bottom of the second cylinder.

[0038] Figure 9 This is a schematic diagram of the mold structure for process S401. Detailed Implementation

[0039] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0040] The rotor cup housing product required for this invention uses DC04 cold-rolled steel plate as raw material. It is a deep-drawing material with advantages such as low yield strength, moderate tensile strength, and high elongation. It is manufactured using a 3.5mm thick circular flat plate as blank. The material around the bearing hole of the housing bearing chamber is thickened to more than 7.5mm in some areas. The outer diameter of the product is 111.6mm, the height is 61mm, the bearing hole diameter is 11.96mm, and the tolerance zone is only 0.05mm. The dimensional accuracy of the forming is high, and there are requirements for the product's contour, total runout, and other geometric tolerances, as well as dynamic balancing tests on the finished product. Because the outer diameter of the product is large and the diameter of the bearing hole is small, the ratio of the bearing hole diameter to the outer diameter of the housing is large (close to 1:10). If conventional stretching forming process is used, it is difficult for the raw material to flow to the bearing hole. Usually, multiple processes are used to gradually stretch and form the bearing hole, but the material thickness of the outer wall of the bearing hole will become thinner, and the purpose of thickening will not be achieved.

[0041] The structural characteristics of the rotor cup housing product required for this invention are as follows: Figure 3 As shown, if conventional stretch forming processes are used, the material at the radius (R) corner around the bearing hole will increase, even while maintaining the inner R corner size. The stretching and back-building process cannot meet the requirement of doubling the local material thickness, and problems such as insufficient material flow and uneven material thickness distribution in the cross-section will occur. This is because localized material thickening exacerbates stress concentration, especially in the R corner transition area, where even minor machining defects or process deviations can lead to premature failure. (See attached diagram.) Figure 4 As shown, if a pressing rib is added to the inner side of the R-corner around the bearing hole through the extrusion process, it will not be able to meet the requirements of the drawing for the inner R-corner profile and the local material thickness.

[0042] The present invention relates to a process for locally thickening the material at the R-angle of the bearing hole periphery in the rotor cup housing bearing chamber. This process aims to increase the material thickness at the R-angle periphery of the bearing hole in the rotor cup housing bearing chamber through integrated molding, while ensuring only a slight reduction in the bearing chamber wall thickness. (See attached diagram.) Figure 5 As shown, the process mainly consists of six steps: pre-stretching, main stretching, pre-punching of bearing holes, back-bearing and back-bearing of shrinkage holes, and final stretching and finishing.

[0043] S10: Pre-stretching.

[0044] S101: Using 3.5mm thick DC04 cold-rolled steel sheet as raw material, a circular flat blank is used as the blank for stretching. The stretching coefficient is 0.68, and the stretching gap is 1.1 times the material thickness. After stretching, it is formed into a first cylinder with a tapered top and an open bottom. The outer diameter of the first cylinder is 137.8mm, the height is about 56mm, and the depth is 52mm. The inner diameter of the upper and lower sides of the tapered part is R20, and the outer diameter of the bottom opening is R12.

[0045] S102: The top center of the first cylinder is stretched inward in the opposite direction to form the second cylinder, which is used as pre-storage material for the subsequent bearing chamber; the outer diameter of the first cylinder is 137.8mm and the height is 50.84mm, the outer diameter of the second cylinder is 59.59mm, the inner diameter is 52.6mm and the depth is 22mm, the inner diameter of the bottom R-angle of the second cylinder is R8, the inner diameter of the R-angle at the transition part between the top of the second cylinder and the first cylinder is R10, the inner diameter of the R-angle on the lower side of the tapered part at the top of the first cylinder is R16, and the outer diameter of the R-angle at the opening part at the bottom of the first cylinder is R12.

[0046] The inner diameter of the second cylinder is formed with a large radius R10 at the top using a concave die and with a large radius R8 at the bottom using a convex die. This facilitates material flow and minimizes the amount of material thinning.

[0047] The two stretching processes of S10 are the preliminary stretching and forming of the rotor cup housing and the preparatory process for stretching and storing the bearing chamber.

[0048] S20: Main tension.

[0049] While maintaining the outer diameter of the first cylinder at 137.8 mm, the second cylinder undergoes multi-stage inward reverse stretching to gradually reduce its inner and outer diameters (i.e., the inner and outer diameters of the bearing bore in the bearing housing). The stretching coefficient is 0.8, and the stretching gap is 1.1 times the material thickness. Through four reverse stretching processes S201-S204, the outer diameter of the second cylinder is gradually reduced to 27.4 mm, and the inner diameter is gradually reduced to 20.4 mm. After stretching in process S201, the height of the formed first cylinder is 51.2 mm, and the height of the second cylinder is 21.5 mm. The inner diameter of the top R-angle of the formed second cylinder is R8, and the outer diameter is R11.5, which remains unchanged during stretching processes S202-S204. However, the inner diameter of the bottom R-angle of the second cylinder is reduced from R8 in process S201 to R5.

[0050] S20 achieves controllable plastic deformation of the material in localized areas through multi-stage stretching, forming a specific R-angle structure with curvature conforming to the design concept. In conventional processes, S20 is typically achieved by gradually reducing the diameter while increasing the stretching height. This is because, under the principle of constant material volume, as the diameter decreases, the material flows towards the height, inevitably increasing the height—hence the use of a process that reduces the diameter while increasing the height. However, as seen through the four reverse stretching processes S201-S204, while reducing the diameter of the second cylinder, the stretching height in each process remains unchanged at 21.5mm. The advantage of this is that it maintains the uniformity of the wall thickness of the material around the bearing hole without increasing the stretching height, avoiding the material thinning phenomenon that occurs in conventional processes due to increased stretching height.

[0051] S20 forms the inner diameter R8 of the R-angle at the top of the second cylinder using a concave die. This is the required dimension for the housing product. This dimension remains unchanged in all subsequent processes. It serves as a reference point for the local material thickening of the R-angle around the bearing hole of the rotor cup housing bearing chamber. Based on this, the contour requirements of the finished product can be guaranteed after the material is thickened at the R-angle.

[0052] Appendix Figure 6 The diagram shown is a schematic of the mold structure for process S201 (mold closed). (Attached) Figure 7 The diagram shows the mold structure for process S204 (open mold state). In S204, an upper mold pusher with a contoured surface is installed on the mold, making the molding process rely on the dynamic matching between the contoured surface and the material flow, achieving a relatively consistent molding force in both the radial and tangential directions. During this process, a small portion of material flows back to the top surface of the housing. This is mainly achieved by using the pressure of the press in conjunction with the contoured surface to apply localized strong pressure to the backflowing material, forcing it to flow towards the top of the bearing hole, thus providing an auxiliary effect of thickening the radius (R-angle).

[0053] S30: Pre-punched bearing bore.

[0054] An 8mm diameter hole is punched in the center of the bottom of the second cylinder as a pre-punch hole for forming the bearing chamber, preparing for the flanging forming in S40. Simultaneously, the top plane of the first cylinder is shaped, causing some material that flowed back to the top surface of the first cylinder in S20 to be squeezed to the R-corner of the bottom opening of the first cylinder through shaping, improving the flatness of the top surface and establishing a planar reference for subsequent forming. After S30, the height of the first cylinder is slightly reduced to 51.1mm, and the inner diameter of the R-corner at the top of the second cylinder is R8, and the outer diameter is R11.5.

[0055] S40: Bearing hole flanging and stretching after flanging.

[0056] S401: While straightening the bottom plane of the round hole, the outer diameter of the second cylinder is reduced to 22.2mm, the inner diameter is reduced to 16.2mm, and the height is shortened to 18.5mm. The top of the second cylinder is formed with a concave mold to form an inner diameter of R8. The material flow causes the outer diameter to be reduced to R8.

[0057] In a conventional flanging and straightening process, the flat material changes from a horizontal to an axially vertical state, and the bottom flat material increases in height after being flanged and compressed by the flanging punch. However, through... Figure 5 As can be seen in the S401 process, after forming in the S401 process, the inner diameter of the flange becomes smaller, and the height of the bearing hole is shortened from 21.5mm in the S30 process to 18.5mm. This result is achieved by adding a height limiting device inside the mold. First, the flange action is completed, and then the increased flange height is constrained by the height limiting device inside the mold to form a fixed height.

[0058] Combined with appendix Figure 9 As shown, when the upper push block of the mold contacts the upper surface of the product, it forcibly squeezes the material in the bearing hole. Under the strong pressure of the press, the material is enclosed by both the flanging die and the flanging punch. The material that is flanged and pulled up flows into the cavity (i.e., the gap outside the R-angle at the top of the second cylinder) under the combined action of the height limiting device inside the mold and the press. At this time, the R-angle changes, and the outer diameter of the R-angle decreases from R11.5 in the S30 process to R8, realizing the first thickening of the R-angle around the bearing hole.

[0059] In this process, the mold structure design is combined with material flow, and the material thickening mechanism is the result of the combined effects of mechanical loading, mold cavity geometric constraints, and material properties. The initial local thickening of the radius (R-angle) is achieved through pressure, forming path, and process parameters.

[0060] S402: Continue to stretch the second cylinder, so that the outer diameter of the second cylinder is reduced to 19mm, the inner diameter is reduced to 13mm, and the height is increased to 20.5mm. The top of the second cylinder is formed with a concave die to form an inner diameter of R8, and the material flow causes the outer diameter to be reduced to R5.

[0061] pass Figure 5 As seen in process S402, the bearing hole height has increased from 18.5mm in process S30 to 20.5mm. This is achieved by adding a height limiting device inside the mold, allowing the bearing hole height to be stretched and increased by 2.0mm while the inner diameter is reduced. Because after the pre-punching of the bearing hole in process S30, as shown in the attached... Figure 8 As shown, there is a radius (R) around the circular hole. During the straightening and flanging process in step S401, when the material changes from horizontal to vertical, there will be a mark at the original transition R-angle, which cannot meet the design requirement of Rz6.3 for the inner wall surface roughness of the bearing hole. Therefore, in step S402, the excess material is bidirectionally distributed, allowing some material to flow to the gap outside the R-angle at the top of the second cylinder using the same method as step S401. This achieves a second thickening of the R-angle around the bearing hole. At the same time, the height limiting device inside the mold is set to allow some material to be stretched and elongated to flow, filling the mark on the inner wall of the bearing hole and making the inner wall smoother, thus meeting the design surface roughness requirements.

[0062] S50: Back pier and narrow hole back pier.

[0063] S501: While keeping the outer diameter of the second cylinder unchanged at 19mm and the inner diameter unchanged at 13mm, the height of the second cylinder is reduced to 18.5mm, and the top of the second cylinder is formed with a concave mold to form an inner diameter of R8. The material flow causes the outer diameter to shrink to R1.5.

[0064] The S501 process needs to be optimized to match the actual material thickness and deformation degree of the product formed in the S402 process. The clearance setting of the die and punch ensures a good fit between the product and the die. Because the S501 process is set so that the inner and outer diameters of the bearing hole do not change, and the dimensions remain the same as in the S402 process, only the height of the bearing hole is re-pressed using the pressure of the press, reducing the height from 20.5mm to 18.5mm. Since the inner and outer diameters of the bearing hole are constrained by the die cavity, the material cannot flow radially. Under the strong pressure of the press, the material is squeezed and flows to the outer gap of the R-angle at the top of the second cylinder, where the outer diameter of the R-angle is squeezed to approximately R1.5, achieving a third thickening of the R-angle around the bearing hole. However, at this point, the inner diameter of the bearing hole (13mm) has not reached the design size, so the thickening of the R-angle has not yet met the minimum wall thickness requirement.

[0065] S502: The height of the second cylinder is reduced to 16.8mm, the outer diameter of the second cylinder is reduced to 18mm, the inner diameter is reduced to 12mm, the top of the second cylinder is formed with a concave mold to form an inner diameter of R8, and the material flow causes the outer diameter to be reduced to R1.

[0066] By setting the punch diameter to 12.0mm and the die diameter to the bearing chamber design size of 18.0mm, the bearing hole diameter is reduced to 12.0mm through punch size reduction. Then, the bearing chamber height is increased by press pressure, ensuring the bearing hole inner diameter basically meets the design size requirements. Simultaneously, some material is squeezed and flows to the outer gap of the R-angle at the top of the second cylinder, further reducing the R-angle outer diameter to approximately R1, achieving the fourth thickening of the bearing hole's perimeter R-angle. After the S502 process, the bearing hole inner diameter and the surrounding R-angle material thickening have initially met the product design requirements.

[0067] S60: Final pull finishing.

[0068] S601: Perform final stretching on the product, stretching the first cylinder to an outer diameter of 111.2mm, and simultaneously reshape the top plane of the first cylinder to increase the height of the second cylinder to the designed size of 18mm.

[0069] Because the force of the back-piling in processes S501 and S502 is relatively large, some excess material returns to the top plane of the first cylinder, resulting in a serious unevenness on the top surface. After process S502, the bearing chamber height of 16.8mm did not reach the design size of 18mm. Therefore, in process S601, while forming the outer diameter of the product, the top plane is also flattened. After flattening, the height of the bearing chamber is increased again and restored to 18mm.

[0070] S602: Perform fine finishing on the product so that the outer and inner diameters of the first cylinder, the top plane of the first cylinder, and the outer and inner diameters of the second cylinder meet the design dimensions of the casing product.

[0071] After the S602 process is completed, the thickening of the radius (R) around the bearing bore in the bearing housing is finished.

[0072] S70: Edge trimming, chamfering, and deburring.

[0073] The product is finished by performing three processes, S701-S703, to cut edges, chamfer, and deburr, thereby completing the shaping of other aspects of the product and completing the finished product of this application.

[0074] This invention optimizes the distribution and quantitative flow control of metal flow during the plastic deformation process of stretch forming, achieving integrated material thickening in the bearing chamber region. This precise control of material flow enables localized directional material thickening, resulting in a housing product where the material thickness at the R-angle around the bearing bore in the bearing chamber is more than double the original thickness. Simultaneously, the bearing chamber wall thickness is only slightly reduced, ensuring the rotor cup housing is successfully manufactured and improving forming quality. The product achieves higher mechanical strength, dimensional accuracy, and surface quality. Details are as follows:

[0075] 1. The main stretching step adopts a variable strain rate control strategy, which is different from the conventional process of reducing the diameter and increasing the stretching height. Instead, the stretching height is not changed while the diameter of the bearing chamber is gradually reduced. This achieves the goal of filling the concave mold cavity with material without thinning the material during stretching, and ensures the uniformity of the wall thickness of the material around the bearing hole. In the overall process of this invention, this step ensures the uniformity of the stretching thickness of the bearing hole material in the initial stage, laying a good foundation for meeting the dynamic balance test of the finished product.

[0076] 2. To address the issue of uneven material flow during the thickening process in traditional processes, a dynamic compensation strategy based on strain field distribution is proposed. In the bearing hole flanging and post-flanging stretching steps, an in-mold height limiting device is set in the mold. In the back-up and shrinkage hole back-up steps, an elastic compensation structure is formed by setting the gap between the die and punch of the mold. This allows for real-time adjustment of the contact pressure distribution during the forming process, guiding the material to flow directionally towards the gap outside the R-angle around the bearing hole.

[0077] 3. The overall process design of this invention comprehensively considers the material's yield strength, plastic deformation limit, and thermodynamic properties, given that a blank thickness of 3.5mm is considered relatively thick. This ensures that the R-corner structure meets dimensional requirements while possessing sufficient mechanical performance redundancy. The initial stretching outer diameter is designed to be 137.8mm. Based on this, various forming steps for thickening the bearing hole material are performed. Because the mold parts need to withstand enormous radial tensile and tangential compressive stresses during the material thickening process, high strength and hardness requirements are placed on the mold parts. Initially, a large-diameter stretching punch is used to stretch the first cylinder as a carrier for the localized material thickening of the bearing chamber. This ensures that the mold parts have sufficient strength, guaranteeing the continuous implementation of the mold forming scheme during the stress process of multiple processes. Finally, after the R-corner material thickening is completed, the remaining processes are carried out. If the material around the bearing hole is thickened and stretched after the outer diameter is formed, the lower punch has a small diameter and insufficient strength during the continuous forming process of the bearing chamber. This will lead to the core cracking or micro-deformation during the continuous stress process of multiple processes. If this process defect occurs, it is irreversible and will cause the entire process design to fail. Therefore, the overall process design of this invention reasonably matches the forming sequence.

[0078] 4. The present invention combines process technology with mold structure design, providing a complete technical solution for the precision forming of rotor cup housings. Using a 1250-ton press as the main equipment, and employing a multi-station robotic arm to transfer the mold, automated continuous production is achieved, offering advantages such as high production efficiency, safe and reliable production process, and low energy consumption. Optimizing the composite process of stretching and local thickening reduces energy loss from multiple stamping passes, resulting in a more than 25% reduction in forming energy consumption compared to traditional technologies.

Claims

1. A rotor cup housing bearing chamber bearing hole peripheral R angle forming local material thickening process, characterized in that Includes the following steps: S10: Pre-stretching; S101: A circular flat plate is stretched to form a first cylinder with a tapered top and an open bottom; the inner diameter of the upper and lower sides of the tapered part is R20, and the outer diameter of the bottom opening part is R12. S102: The top middle of the first cylinder is stretched inward to form a second cylinder. The inner diameter of the bottom R-angle of the second cylinder is R8, the inner diameter of the R-angle of the transition part between the top of the second cylinder and the first cylinder is R10, the inner diameter of the R-angle of the lower side of the tapered part at the top of the first cylinder is R16, and the outer diameter of the R-angle of the opening part at the bottom of the first cylinder is R12. S20: Main tension; While keeping the outer diameter of the first cylinder constant, the second cylinder continues to be stretched inward in multiple stages, gradually reducing its inner and outer diameters. The inner diameter of the top R-angle of the second cylinder formed after the first reverse stretch is R8, the outer diameter is R11.5, and the height of the second cylinder remains unchanged in subsequent reverse stretches. However, the inner diameter of the bottom R-angle of the second cylinder is gradually reduced from R8 to R5, thereby ensuring the uniformity of the wall thickness of the second cylinder without increasing the stretching height. The inner diameter R8 of the top R-angle of the second cylinder serves as the reference point for subsequent local material thickening. S30: Pre-punched bearing bore; A round hole is punched in the middle of the bottom of the second cylinder as a pre-punch hole for forming the bearing chamber. At the same time, the top plane of the first cylinder is shaped so that part of the material flowing back to the top surface of the first cylinder in S20 is squeezed to the R-corner of the bottom opening of the first cylinder through the shaping. S40: Bearing hole flanging and stretching after flanging; S401: While straightening the bottom plane of the round hole, the outer diameter and inner diameter of the second cylinder are reduced and the height is shortened. The top of the second cylinder is formed with a concave mold to form an inner diameter of R8. The material flow causes the outer diameter to shrink from R11.5 to R8, realizing the first thickening of the R angle around the bearing hole. S402: Continue to stretch the second cylinder to reduce its outer and inner diameters and increase its height. The top of the second cylinder is formed with a die to create an inner diameter of R8. The material flow causes the outer diameter to shrink from R8 to R5, thus achieving a second thickening of the R-angle around the bearing hole. S50: Back pier and narrow hole back pier; S501: While keeping the outer and inner diameters of the second cylinder unchanged, the height of the second cylinder is increased, and the inner diameter of the R-angle of the top of the second cylinder is formed by a concave die. The material flow causes the outer diameter to shrink from R5 to R1.5, thus achieving the third thickening of the R-angle around the bearing hole. S502: Continue to increase the height of the second cylinder and reduce the outer and inner diameters of the second cylinder. The top of the second cylinder is formed with a concave die to form an inner diameter of R8. The material flow causes the outer diameter to shrink from R1.5 to R1, thus achieving the fourth thickening of the R angle around the bearing hole. S60: Final pull finishing; The product undergoes final stretching and finishing to shape the outer diameter of the first cylinder, the height of the second cylinder, and the top plane of the first cylinder to conform to the design dimensions.

2. The rotor cup housing bearing compartment bearing bore periphery R angle formation partial material thickening process of claim 1 wherein: In S101, the thickness of the circular flat plate is 3.5mm. It is made of DC04 cold-rolled plate and stretched with a tensile coefficient of 0.68 and a stretching gap of 1.1 times the material thickness.

3. The local material thickening process for forming the R-angle around the bearing hole of the rotor cup housing bearing chamber according to claim 1, characterized in that: In S10 and S20, the R-angle is set by the mold to ensure the inner and outer diameters of the R-angle formed by the product.

4. The local material thickening process for forming the R-angle around the bearing hole of the rotor cup housing bearing chamber according to claim 1, characterized in that: In S20, stretching is performed with a tensile coefficient of 0.8 and a stretching gap of 1.1 times the material thickness.

5. The process for locally thickening the material around the bearing hole of the rotor cup housing bearing chamber according to claim 1, characterized in that: In S20, an upper mold push block with a contoured surface is provided, and the contoured surface acts on the top plane of the first cylinder.

6. The local material thickening process for forming the R-angle around the bearing hole of the rotor cup housing bearing chamber according to claim 1, characterized in that: In both S401 and S402, a height limiting device is set inside the mold to ensure the forming height of the second cylinder.

7. The local material thickening process for forming the R-angle around the bearing hole of the rotor cup housing bearing chamber according to claim 1, characterized in that: In S60, S601 performs final stretching of the product, stretching the outer diameter of the first cylinder and the height of the second cylinder to meet the design dimensions. During the stretching process, the unevenness caused by some material flowing back to the top surface of the first cylinder in S50 is shaped into a flat surface. S602 performs fine finishing of the product, so that the outer and inner diameters of the first cylinder, the top plane of the first cylinder, and the outer and inner diameters of the second cylinder meet the design dimensions of the casing product.

8. The process for locally thickening the material around the bearing hole of the rotor cup housing bearing chamber according to claim 1, characterized in that: After S60 is completed, the edges are trimmed, chamfered, and deburred to complete the other aspects of the product forming.

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