Processing method of crown-shaped bearing retainer

Abstract

The machining method comprises the steps that a round material piece is punched on a base material, in the discharging process, a positioning hole is synchronously punched in the middle of the round material piece, and the positioning hole is configured to limit rotation of the material piece when matched with an adaptive positioning structure; the round material sheet is stretched into a bowl-shaped material sheet comprising a round bottom wall and an annular side wall, the positioning hole is located in the middle of the round bottom wall, and the annular side wall extends in the axial direction of the round bottom wall; a plurality of side holes distributed at equal intervals are formed in the annular side wall in a stamping mode in the circumferential direction, the side holes are integrally circular, and an opening is formed in the free end of the annular side wall; the edge of the side hole is folded outwards in the radial direction of the annular side wall to form a turned edge, the inner surface of the turned edge is in a spherical surface shape, then a pocket hole is formed, and convex parts are formed on the two sides of the pocket hole; a round area with the preset diameter is cut off from the middle of the round bottom wall. According to the method, the material utilization rate is remarkably increased, the process stability, the cage forming precision and the anti-fatigue performance are improved, and the fracture risk is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of bearing processing, and particularly relates to a processing method for a crown-shaped bearing cage. Background Art

[0002] A bearing cage is an important component of a bearing, which partially wraps and isolates all rolling elements, guides the rolling elements to roll and holds them between the inner ring and the outer ring of the bearing. There are various types and structures of bearing cages, including a crown-shaped bearing cage. As Figure 2 shown, the existing crown-shaped bearing cage includes an annular main body 11 and a plurality of convex portions 12. The plurality of convex portions 12 are circumferentially and equidistantly connected to the outer edge of the main body 11 and protrude axially. Pocket holes 13 for restricting balls are formed between adjacent convex portions 12. The edges of the pocket holes 13 are radially turned outwards, aiming to expand the area of the inner surface and limit the balls through the flanging. The crown-shaped bearing cage is a core component of a precision rolling bearing, and the accuracy of its pocket holes directly affects the load distribution, frictional loss and noise level of the bearing.

[0003] The traditional processing method of the crown-shaped bearing cage adopts the process of "blanking - stretching - flanging - bottom cutting". Among them, as Figure 1 shown, in the blanking process, a planar blank 10 similar to a petal shape is blanked from a base material. A plurality of radially extending convex portions are circumferentially and equally spaced on the blank. In the stretching process, the originally radially extending convex portions are stretched into axially extending ones, and pocket holes are formed between adjacent convex portions. In the flanging process, the edges of the pocket holes are radially turned outwards. In the bottom cutting process, the middle region of the blank is cut off according to a preset diameter, so that the contour of the crown-shaped bearing cage is basically formed. However, this processing method has the following defects: punching the petal-shaped blank generates a large amount of scrap, and the material utilization rate is relatively low, even less than 50%. Moreover, the special-shaped nesting increases the complexity of the die; there are mainly two ways of stretching the convex portions, namely stretching one by one and synchronous stretching. It is difficult to ensure the stretching consistency in the way of stretching one by one, and it is easy to cause the deviation of the spherical shape of the pocket hole due to material springback and requires secondary correction; the way of synchronously stretching all convex portions has high requirements for the structure and control of the stretching die, poor process stability, and easy fracture of the material fiber direction; manual positioning is relied on between multiple processes, and the cumulative error causes uneven circumferential distribution of the convex portions, ultimately resulting in poor forming quality of the cage; direct stretching causes stress concentration at the root of the convex portions, and the fatigue crack propagation rate is fast, which is not conducive to extending the service life. Summary of the Invention

[0004] The present application provides a processing method for a crown-shaped bearing cage to solve the technical problems existing in the prior art.

[0005] The technical solution adopted by the present application is as follows:

[0006] A processing method for a crown-shaped bearing cage, the crown-shaped bearing cage comprising a circular main body and a plurality of convex portions, the plurality of convex portions being circumferentially and equidistantly connected to the outer edge of the main body and protruding axially, and a pocket for restricting balls being formed between adjacent convex portions, the edge of the pocket being radially turned outwards. The method comprises: S1 blanking, punching out a circular blank on a base material, and during the blanking process, simultaneously stamping a positioning hole in the middle of the circular blank, the positioning hole being configured to restrict the rotation of the blank when cooperating with a matching positioning structure; S2 stretching, stretching the circular blank into a bowl-shaped blank comprising a circular bottom wall and an annular side wall, the positioning hole being located in the middle of the circular bottom wall, and the annular side wall extending axially along the circular bottom wall; S3 punching, stamping a plurality of equally spaced side holes in the annular side wall in the circumferential direction, the side holes being circular as a whole and having an opening provided at the free end of the annular side wall; S4 flanging the side edge, turning the edge of the side hole outwards in the radial direction of the annular side wall to form a flange, the inner surface of the flange being spherical, thereby forming a pocket, and convex portions being formed on both sides of the pocket; S5 bottom cutting, cutting out a circular area with a preset diameter in the middle of the circular bottom wall.

[0007] In this technical solution, through the process path of integrally blanking and stretching a circular blank into a bowl shape, step-by-step punching and side edge flanging, and finally bottom cutting, the complex deformation process of directly stretching a traditional petal-shaped blank is replaced. The stamping process of the circular blank is more regular, and the material utilization rate is significantly improved. At the same time, the precise positioning of the positioning hole can penetrate multiple processes or even the entire process, ensuring the concentricity and circumferential uniform distribution accuracy of steps such as stretching, punching, and side edge flanging, reducing the cumulative error caused by multiple positioning in different ways, and improving the process stability and the forming accuracy of the cage. By first stretching the bowl-shaped structure, punching side holes, and separately flanging the side edge, controlling the deformation step by step, the risk of tolerance accumulation is further reduced, and the spherical accuracy of the pocket is improved. The standard punching die can be used for blanking the circular blank in this method, which simplifies the die design, is easier to realize automatic feeding and positioning, reduces the maintenance cost, and improves the production efficiency, being suitable for large-scale manufacturing. Compared with the traditional process of directly stretching the convex portion from the radial direction to the axial direction, in this method, through bowl-shaped stretching, the material flow of the annular side wall is more uniform, stress concentration is reduced, the anti-fatigue performance of the cage is improved, and the fracture risk is reduced.

[0008] In the S1 blanking process, a circular blank and a positioning hole are formed on the base material through a compound punching die. The compound punching die comprises an upper punch and a lower die, a lower punch is arranged in the lower die, and a waste hole adapted to the lower punch is arranged in the upper punch; the upper punch moves downwards to be combined with the lower die, the upper punch applies a downward punching force to the base material, thereby punching out a circular blank. At the same time, the lower punch moves upwards into the waste hole, applying an upward punching force to the base material, thereby stamping a positioning hole.

[0009] In this technical solution, the downward blanking force and the upward blanking force acting in opposite directions apply forces synergistically. During the process of simultaneously punching the circular blank and the positioning hole, dynamic stress balance and energy collaborative utilization are achieved. The design of the reverse force system makes the internal stress distribution of the material more uniform, effectively reduces the maximum stress peak value, effectively inhibits the warping of the blank, and at the same time, part of the blanking shear energy is converted into tensile plastic deformation energy, reducing the total stamping energy consumption by a certain proportion.

[0010] A counter-pressure die is provided inside the lower female die. The lower female die, the counter-pressure die, and the lower punch are nested in sequence from the outside to the inside. In the S1 blanking process, the counter-pressure die and the upper punch clamp the base material together. The counter-pressure die applies an upward counter-pressure to the base material. The counter-pressure is less than the downward blanking force. The counter-pressure die and the upper punch move downward synchronously, and the resultant force of the downward blanking force and the counter-pressure punches out the circular blank.

[0011] In this technical solution, the counter-pressure die and the upper punch move synergistically. The counter-pressure die provides a counter-pressure to assist in punching the circular blank, balancing the material stress at the moment of blanking, and the resultant force direction of the counter-pressure and the downward blanking force is controllable, making the blanking fracture surface of the circular blank flatter, reducing burrs and warping deformation, ensuring the flatness of the circular blank. This punching action method with multiple force sources can more accurately complete the forming of the circular blank and improve the forming quality.

[0012] The composite blanking die includes a positioning pressure plate. The positioning pressure plate is provided with pressing teeth surrounding the upper punch. When the upper punch punches, the pressing teeth press the edge of the circular blank.

[0013] In this technical solution, the pressing teeth of the positioning pressure plate press the edge of the circular blank during blanking, forming a "blank-holding ring" effect. It can not only apply a downward pressure to the blank, but also apply a lateral pressure using its tooth shape structure, restricting the lateral flow of the material during blanking, forcing the material to gather towards the center, compensating for the thinning trend of the cylinder wall thickness during the stretching process, reducing edge tearing or micro-cracks caused by the shear force, and improving the blanking quality. Through the combined action of the blank-holding force of the pressing teeth, the downward blanking force of the upper punch, and the counter-pressure of the counter-pressure die, it is ensured that the blank remains stable during blanking, thereby obtaining a high-quality shear surface.

[0014] In the S2 stretching process, the circular blank is stretched into a bowl-shaped blank using a multi-stage progressive stretching process. The multi-stage progressive stretching process specifically includes: the first-stage stretching: pre-stretching the circular blank into a conical structure with an obtuse angle between the circular bottom wall and the annular side wall; the second-stage stretching: further stretching the conical structure into a bowl-shaped structure with the circular bottom wall and the annular side wall perpendicular, realizing the axial extension of the annular side wall along the circular bottom wall; the third-stage stretching: locally shaping the annular side wall of the bowl-shaped structure to eliminate wrinkles.

[0015] In this technical solution, the multi-stage progressive stretching process controls the deformation amount in stages, from a plane to an obtuse cone and then to a vertical bowl shape, so that the material fibers are gradually extended rather than stretched violently at one time. The obtuse cone can better disperse the stress during the stretching process and avoid the risk of rupture of the annular side wall due to excessive thinning; eliminating side wall wrinkles can improve the surface quality of the bowl-shaped sheet and reduce stress concentration in subsequent punching and flanging.

[0016] The S3 punching process adopts a split punching mold, which includes an outer mold, an inner mold and a punch needle. The outer mold has a cavity matching the outer contour of the bowl-shaped sheet, the diameter of the inner mold is smaller than the inner diameter of the annular side wall, the inner mold is provided with a positioning protrusion adapted to the positioning hole, the punch needle is arranged in the outer mold and can move radially along the annular side wall, and the punch needle head is a conical structure; during punching, the circular bottom wall and the annular side wall of the bowl-shaped sheet are respectively abutted against the inner wall of the outer mold cavity, the inner mold is inserted into the bowl-shaped sheet and clamps the circular bottom wall with the outer mold, the positioning protrusion is plug-fitted with the positioning hole to limit the rotation of the bowl-shaped sheet, and the punch needle penetrates the annular side wall from the outside to the inside to form a side hole. During the stamping process, the inner surface of the cavity is completely fitted with the outer wall of the bowl-shaped sheet, forming a rigid support, which provides reaction support for the inward force of the punch needle, avoiding the overall concave of the annular side wall. The inner die is close to the circular bottom wall to prevent the circular bottom wall material from arching up when punching the side hole, avoiding the distortion of the annular side wall. The inner die and the outer die cooperate to form a clamp to fix the position of the bowl-shaped sheet and inhibit the flow of material. The conical tip of the punch needle first pierces the annular side wall, gradually expanding the perforation and reducing the instantaneous impact force. The annular side wall is gradually cut rather than torn all at once, reducing the tendency to shrink.

[0017] In the present technical solution, the outer die of the split punching die matches the outer contour of the bowl-shaped sheet, and the inner die is plugged into the positioning hole through the positioning protrusion to achieve two-way clamping and fixation during punching, limiting the axial displacement and circumferential rotation of the bowl-shaped sheet, and when the punch needle penetrates the annular side wall, the outer die and the inner die cooperate to limit the radial deformation of the annular side wall, reducing the circumferential distribution angle error of the side hole, ensuring the consistency of the side hole, and the conical punch needle head helps to reduce the blanking resistance and reduce the burr height of the side hole edge, thereby reducing the pre-processing amount of the subsequent flanging process.

[0018] The inner mold is rotatable by being driven by a servo motor. When the servo motor drives the inner mold to rotate, the inner mold synchronously drives the bowl-shaped sheet to rotate in the cavity through the cooperation between the positioning protrusion and the positioning hole. During stamping, the servo motor drives the inner mold and the bowl-shaped sheet to rotate intermittently at a preset angle, so that the parts to be punched on the annular side wall correspond to the punching needle in turn, so that the punching needle punches the annular side wall in turn to form side holes.

[0019] In this technical solution, the servo motor drives the inner mold and the bowl-shaped sheet to rotate intermittently. Combining with the step-by-step punching strategy, it forms the punching operation of the punching pins in sequence, which can be applied to the precision machining of thin-walled or high-hardness materials, and also helps to simplify the structure of the split punching die. At the same time, it ensures the circumferential uniform distribution accuracy of the side holes through rotational positioning and avoids cumulative deviation.

[0020] In the S4 side-turning process, a ball-head spinning tool is used. The ball-head spinning tool includes a spherical head that matches the target curvature of the flanging. During flanging, the spherical head rotates and advances from the inside to the outside on the inner side of the bowl-shaped sheet towards the side hole, and radially folds the edge of the side hole to form a spherical pocket hole.

[0021] In this technical solution, the ball-head spinning tool flanges from the inside to the outside. By using the progressive extrusion of the spherical head on the material at the edge of the side hole, it forms a spherical pocket hole that matches the curvature of the ball. Compared with traditional stamping flanging, it helps to reduce the surface roughness of the inner surface of the pocket hole, reduce the friction coefficient of the contact surface of the ball, and avoid cracking of the outer-turned edge.

[0022] In the S4 side-turning process, after the formation of the pocket hole, a rolling strengthening process is added. The inner wall of the pocket hole is rolled to cause plastic deformation of the material on the inner wall of the pocket hole.

[0023] In this technical solution, through the cold work hardening effect, the rolling strengthening process refines the surface grains of the material on the inner wall of the pocket hole, improves the hardness, and at the same time eliminates the residual tensile stress after flanging and prolongs the fatigue life, which meets the long-term reliability requirements of the cage for high-speed bearings.

[0024] In the S5 bottom-cutting process, a laser cutting process is used. The specific laser cutting process is as follows: the laser cutting head cuts the middle area of the circular bottom wall along a preset circular path. During the cutting process, an inert gas is sprayed into the cutting area to cool the edge of the cut. After cutting is completed, deburring treatment is performed on the cut.

[0025] In this technical solution, the laser cutting process removes the circular bottom surface through non-contact thermal melting. The width of the cut is small, and the deformation amount is reduced compared with mechanical punching. The inert gas cooling avoids oxidation of the cut. After deburring, it can be directly assembled, which helps to reduce the post-processing working hours.

[0026] Due to the adoption of the above technical solution, the technical effects achieved by this application are as follows: By means of the process path of integrally blanking and stretching a circular blank into a bowl shape, step-by-step punching and flanging, and finally bottom cutting, the complex deformation process of directly stretching a traditional petal-shaped blank is replaced. The stamping process of the circular blank is more regular, and the material utilization rate is significantly improved. At the same time, the accurate positioning of the positioning holes throughout multiple processes or even the entire process can be utilized to ensure the concentricity and circumferential uniform distribution accuracy of steps such as stretching, punching, and flanging, reduce the cumulative error caused by multiple positioning in different ways, and improve the process stability and the forming accuracy of the cage. By first stretching the bowl-shaped structure, punching side holes, and flanging separately, the deformation is controlled step by step, further reducing the risk of tolerance accumulation and improving the spherical surface accuracy of the pocket holes. The circular blank can be blanked by using a standard punching die in this method, which simplifies the die design, makes it easier to achieve automatic feeding and positioning, reduces the maintenance cost, and improves the production efficiency, being suitable for large-scale manufacturing. Compared with the traditional process of directly stretching the convex part from the radial direction to the axial direction, in this method, through bowl-shaped stretching, the material flow of the annular side wall is more uniform, stress concentration is reduced, the anti-fatigue performance of the cage is improved, and the fracture risk is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of this application and form a part of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0028] Figure 1 is the process flow chart of the traditional processing method of the crown-shaped bearing cage provided by this application;

[0029] Figure 2 is the structural schematic diagram of the crown-shaped bearing cage provided by this application;

[0030] Figure 3 is the structural schematic diagram of punching out a circular blank on a base material on the composite blanking die provided by this application;

[0031] Figure 4 is the process flow chart of the processing method of the crown-shaped bearing cage provided by this application;

[0032] Figure 5 is the structural schematic diagram of the outer die of the split punching die provided by this application;

[0033] Figure 6 is the assembly drawing of the inner die and the servo motor of the split punching die provided by this application;

[0034] Figure 7 is the structural schematic diagram of the split punching die for stamping a bowl-shaped blank.

[0035] List of components and reference numerals:

[0036] 11 Main body, 12 convex part, 13 pocket hole;

[0037] 20 Base material, 21 circular sheet, 22 positioning hole, 23 circular bottom wall, 24 annular side wall, 25 bowl-shaped sheet, 26 side hole, 27 flanging;

[0038] 31 Upper punch, 32 lower die, 33 lower punch, 34 waste hole, 35 counter-pressure die, 36 positioning pressure plate, 37 blank-holding teeth, 38 upper die holder, 39 lower die holder;

[0039] 41 Outer die, 411 cavity, 42 inner die, 421 positioning convex part, 43 punch pin, 44 servo motor. Specific embodiments

[0040] In order to more clearly illustrate the overall concept of the present application, the following will be described in detail by way of examples in conjunction with the accompanying drawings of the specification.

[0041] In the following description, many specific details are set forth in order to fully understand the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0042] In the present application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description of reference terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0043] Different from Figure 1 the traditional processing method shown, the present application provides a method for processing a crown-shaped bearing cage. As Figure 2 shown, the crown-shaped bearing cage includes a circular ring-shaped main body 11 and a plurality of convex parts 12. The plurality of convex parts 12 are circumferentially and equidistantly connected to the outer edge of the main body 11 and protrude axially. The pockets 13 for restricting the ball bearings are formed between adjacent convex parts 12, and the edges of the pockets 13 are radially turned outwards. Refer to Figures 3 to 7 shown, the method includes:

[0044] S1 Blanking: Punch out a circular blank 21 on the base material 20. During the blanking process, a positioning hole 22 is simultaneously punched in the middle of the circular blank 21. The positioning hole 22 is configured to restrict the rotation of the blank when cooperating with a matching positioning structure.

[0045] S2 Stretching: Stretch the circular blank 21 into a bowl-shaped blank 25 including a circular bottom wall 23 and an annular side wall 24. The positioning hole 22 is located in the middle of the circular bottom wall 23, and the annular side wall 24 extends along the axial direction of the circular bottom wall 23.

[0046] S3 Punching holes: Punch a plurality of equally spaced side holes 26 along the circumferential direction on the annular side wall 24. The side holes 26 are integrally circular and have openings at the free ends of the annular side wall 24 (one axial end of the annular side wall 24 is connected to the circular bottom wall 23, and the other axial end is the free end).

[0047] S4 Flanging the side: Turn the edges of the side holes 26 outward along the radial direction of the annular side wall 24 to form flanges 27. The inner surface of the flanges 27 is spherical, thereby forming a pocket hole 13, and convex portions 12 are formed on both sides of the pocket hole 13.

[0048] S5 Bottom cutting: Cut out a circular area with a preset diameter in the middle of the circular bottom wall 23. The preset diameter is determined according to the actual required cage specifications, applications, etc.

[0049] As Figure 4 shown are the structural changes in each step during the processing of the circular blank 21, and finally the profile of the crown-type bearing cage is formed.

[0050] In this technical solution, through the process path of integrally blanking, stretching into a bowl shape, step-by-step punching and flanging the side, and finally bottom cutting of the circular blank 21, it replaces the complex deformation process of directly stretching the traditional petal-shaped blank. The stamping process of the circular blank 21 is more regular, and the material utilization rate is significantly improved. At the same time, the precise positioning of the positioning hole 22 throughout multiple processes or even the entire process can be utilized to ensure the concentricity and circumferential uniform distribution accuracy of steps such as stretching, punching, and flanging the side, reducing the cumulative error caused by multiple positioning in different ways, and improving the process stability and the forming accuracy of the cage. By first stretching the bowl-shaped structure, punching the side holes 26, and separately flanging the side, controlling the deformation step by step, the risk of tolerance accumulation is further reduced, and the spherical accuracy of the pocket hole 13 is improved. The circular blank 21 can be blanked using a standard punching die in this method, which simplifies the die design, makes it easier to achieve automatic feeding and positioning, reduces the maintenance cost, improves the production efficiency, and is suitable for large-scale manufacturing. Compared with the traditional process of directly stretching the convex portion from the radial direction to the axial direction, in this method, through the bowl-shaped stretching, the material flow of the annular side wall 24 is more uniform, reducing stress concentration, improving the anti-fatigue performance of the cage, and reducing the risk of fracture. The shape of the positioning hole 22 is not limited, and it is preferably set as a non-circular hole to facilitate the positioning structure to restrict the rotation of the blank after plugging.

[0051] In a preferred embodiment, the S1 blanking process is implemented in a compound blanking die, and a circular blank 21 and a positioning hole 22 are formed on the base material 20 through the compound blanking die. As Figure 3 shown, the compound blanking die includes an upper punch 31, a lower die 32 and a positioning pressure plate 36. A lower punch 33 is arranged in the lower die 32. A waste hole 34 adapted to the lower punch 33 is arranged in the upper punch 31. A counter-pressure die 35 is arranged in the lower die 32. The lower die 32, the counter-pressure die 35 and the lower punch 33 are nested in sequence from outside to inside. The positioning pressure plate 36 is provided with a flanging tooth 37 surrounding the upper punch 31. Specifically, the upper punch 31 and the positioning pressure plate 36 can be arranged on the upper die base 38, and the lower die 32, the counter-pressure die 35 and the lower punch 33 are arranged on the lower die base 39. The upper die base 38 can move up and down to realize combination or separation from the lower die base 39. The movement of each module in the compound blanking die can be driven by a hydraulic mechanism.

[0052] In a preferred embodiment, the S3 punching process adopts a split punching die, as Figure 5 , Figure 6 and Figure 7As shown, the split punching die includes an outer die 41, an inner die 42 and a punch pin 43. The outer die 41 has a cavity 411 matching the outer contour of the bowl-shaped sheet 25. The diameter of the inner die 42 is smaller than the inner diameter of the annular side wall 24. The inner die 42 is provided with a positioning convex portion 421 adapted to the positioning hole 22. The axial dimension of the positioning convex portion 421 is consistent with the thickness of the circular bottom wall 23. The punch pin 43 is arranged in the outer die 41 and can move radially along the annular side wall 24. The head of the punch pin 43 is a conical structure. The inner die 42 is driven by a servo motor 44 to be rotatable. When the servo motor 44 drives the inner die 42 to rotate, the inner die 42 synchronously drives the bowl-shaped sheet 25 to rotate in the cavity 411 through the cooperation of the positioning convex portion 421 and the positioning hole 22 (the rotation angle each time is the included angle between adjacent side holes 26). Specifically, the outer die 41 and the inner die 42 can be respectively arranged on two die bases. The outer die 41 is located above the inner die 42, and the opening of the cavity 411 faces downward. The bowl-shaped sheet 25 can be pre-positioned on the inner die 42. When the two die bases are combined, the outer die 41 and the inner die 42 clamp the bowl-shaped sheet 25. To facilitate the servo motor 44 to drive the inner die 42 and the bowl-shaped sheet 25 to rotate, the servo motor 44 can be arranged to be liftable. Further, the inner die 42 and the bowl-shaped sheet 25 can be driven to move downward a certain distance in advance, so that the bowl-shaped sheet 25 rotates after moving away from the outer die 41, and then moves upward to be clamped after rotation, avoiding the frictional resistance of the outer die 41 on the bowl-shaped sheet 25 affecting its rotation and also avoiding mutual wear between the two. Since the diameter of the inner die 42 is smaller than the inner diameter of the annular side wall 24, a stamping avoidance space for the punch pin 43 to penetrate the annular side wall 24 is formed between the inner die 42 and the bowl-shaped sheet 25 after the inner die 42 enters the bowl-shaped sheet 25. The movement of each module in the split punching die can be driven by a hydraulic mechanism.

[0053] In a preferred embodiment, a ball head spinning tool is used in the S4 flanging side process. The ball head spinning tool includes a spherical head matching the target curvature of the flange 27. The S5 bottom cutting process uses a laser cutting machine. Specifically, a suitable and mature ball head spinning tool and laser cutting machine can be selected in the market according to actual processing requirements.

[0054] The following unfolds a specific embodiment of this method:

[0055] S1 blanking process: As Figure 3As shown, prepare a suitable base material and place it on the lower die holder 39 of the compound blanking die. The upper die holder 38 and the lower die holder 39 are combined. Then, driven by the hydraulic mechanism, the upper punch 31 moves downward and the lower punch 33 moves upward. At the same time, the counter-pressure die 35 cooperates with the upper punch 31 to clamp the base material and move downward synchronously. Under the combined action of the upper blanking force (F1), the lower blanking force (F2), and the counter-pressure force (F3), a circular blank 21 is blanked, and a positioning hole 22 is formed in the middle thereof. During this process, the flanging teeth 37 of the positioning pressing plate 36 always press the edge of the circular blank 21 to form a flanging force (F4), ensuring that the blanked blank has a regular shape and accurate dimensions.

[0056] S2 Stretching process: Transfer the circular blank 21 with the positioning hole 22 obtained from blanking to the stamping and stretching equipment. The stamping and stretching equipment preferably uses two sets of dies. The male and female dies of one set of dies are used to stretch the circular blank 21 into a conical structure, and the male and female dies of the other set of dies are used to stretch the conical structure into a bowl-shaped blank 25. Operate in sequence according to the steps of the multi-stage progressive stretching process. First, perform the first-stage stretching. The equipment applies a pulling force to the circular blank 21 through the corresponding die, gradually deforming it into a conical structure with an obtuse angle between the circular bottom wall 23 and the annular side wall 24. Then, perform the second-stage stretching to further change the shape of the blank into a bowl-shaped structure with the circular bottom wall 23 and the annular side wall 24 perpendicular. Finally, perform the third-stage stretching to locally shape the annular side wall 24 of the bowl-shaped structure. Specifically, an outward convex arc surface opposite to the direction of the fold depression can be set through the shaping die, and the fold depression area is extruded by the outward convex arc surface to eliminate the folds, and finally a bowl-shaped blank 25 that meets the requirements is obtained.

[0057] S3 Punching process: As Figure 7 shown, place the bowl-shaped blank 25 in the split punching die, make the circular bottom wall 23 and the annular side wall 24 of the bowl-shaped blank 25 respectively fit the inner wall of the cavity 411 of the outer die 41, accurately insert the positioning convex portion 421 of the inner die 42 into the positioning hole 22 of the blank, clamp the circular bottom wall 23 by the inner die 42 and the outer die 41, then start the hydraulic press for driving the punch pin 43 to move back and forth and the servo motor 44 for driving the inner die 42 to rotate. Drive the inner die 42 to rotate intermittently at a preset angle through the servo motor 44. Each time it rotates, make the area of the side hole 26 to be punched correspond to the position where the punch pin 43 is located, then stop rotating, and the punch pin 43 penetrates the annular side wall 24 from the outside to the inside to form a side hole 26. Perform such cyclic operations until a plurality of side holes 26 evenly distributed in the circumferential direction are punched on the annular side wall 24.

[0058] S4 flanging process: the bowl-shaped sheet 25 after punching is placed on the workbench of the flanging process 27, and a ball-head spinning tool is used to rotate and push the spherical head of the tool from the inside to the outside toward the side hole 26 inside the bowl-shaped sheet 25, and radially fold the edge of the side hole 26 to form a spherical pocket 13, and then use a rolling device to roll the inner wall of the pocket 13 to cause the material to undergo plastic deformation and strengthen the structure of the pocket 13.

[0059] S5 bottom cutting process: Place the workpiece that has completed the previous process on the workbench of the laser cutting equipment, set the cutting path of the laser cutting head, and start cutting. During the cutting process, spray inert gas into the cutting area for cooling. After the cutting is completed, deburr the incision to finally obtain the formed crown-shaped bearing cage. Subsequently, heat treatment, polishing and other processes can be continued to form a complete crown-shaped bearing cage product.

[0060] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0061] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A processing method for a crown-shaped bearing cage, the crown-shaped bearing cage comprising an annular main body and a plurality of convex portions, the plurality of convex portions being circumferentially and equidistantly connected to the outer edge of the main body and protruding axially, and a pocket for restricting balls being formed between adjacent convex portions, the edge of the pocket being radially turned outwards, characterized in that, The method includes: S1 Blanking: Punch out circular blanks on the base material. During the blanking process, a positioning hole is simultaneously punched in the middle of the circular blank. The positioning hole is configured to restrict the rotation of the blank when cooperating with a matching positioning structure. S2 Stretching: Stretch the circular blank into a bowl-shaped blank including a circular bottom wall and an annular side wall. The positioning hole is located in the middle of the circular bottom wall, and the annular side wall extends along the axial direction of the circular bottom wall. S3 Punching holes: Punch a plurality of equally spaced side holes along the circumferential direction on the annular side wall. The side holes are integrally circular and have openings at the free ends of the annular side wall. S4 Flanging the side edges: Turn the edges of the side holes outwards along the radial direction of the annular side wall to form flanges. The inner surface of the flanges is spherical, thereby forming pocket holes, and convex parts are formed on both sides of the pocket holes. S5 Bottom cutting: Cut out a circular area with a preset diameter in the middle of the circular bottom wall.

2. The method for machining a crown-shaped bearing cage according to claim 1, characterized in that In the S1 blanking process, a circular blank and a positioning hole are formed on the base material through a compound punching die. The compound punching die includes an upper punch and a lower die. A lower punch is provided in the lower die, and a waste hole adapted to the lower punch is provided in the upper punch. The upper punch moves downward to close the die with the lower die. The upper punch applies a downward punching force to the base material to punch out the circular blank. At the same time, the lower punch moves upward into the waste hole and applies an upward punching force to the base material to punch out the positioning hole.

3. The method for machining a crown-shaped bearing cage according to claim 2, characterized in that A counter-pressure die is provided in the lower die. The lower die, the counter-pressure die, and the lower punch are nested in sequence from the outside to the inside. In the S1 blanking process, the counter-pressure die and the upper punch clamp the base material together. The counter-pressure die applies an upward counter-pressure to the base material. The counter-pressure is less than the punching force. The counter-pressure die and the upper punch move downward synchronously, so that the resultant force of the punching force and the counter-pressure punches out the circular blank.

4. The method for machining a crown-shaped bearing cage according to claim 2, characterized in that The compound punching die includes a positioning pressing plate. The positioning pressing plate is provided with pressing teeth surrounding the upper punch. When the upper punch punches, the pressing teeth press the edge of the circular blank.

5. The method for machining a crown-shaped bearing cage according to claim 1, characterized in that In the S2 stretching process, a multi-stage progressive stretching process is used to stretch the circular blank into a bowl-shaped blank. The multi-stage progressive stretching process specifically includes: The first-stage stretching: Pre-stretch the circular blank into a conical structure with an obtuse angle between the circular bottom wall and the annular side wall. The second-stage stretching: Further stretch the conical structure into a bowl-shaped structure with the circular bottom wall and the annular side wall perpendicular, realizing the axial extension of the annular side wall along the circular bottom wall. The third-stage stretching: Locally shape the annular side wall of the bowl-shaped structure to eliminate wrinkles.

6. The method for machining a crown-shaped bearing cage according to claim 1, characterized in that The S3 punching process uses a split punching die. The split punching die includes an outer die, an inner die, and a punch pin. The outer die has a cavity that matches the outer contour of the bowl-shaped blank. The diameter of the inner die is smaller than the inner diameter of the annular side wall. The inner die is provided with a positioning convex portion adapted to the positioning hole. The punch pin is disposed within the outer die and can move radially along the annular side wall. The head of the punch pin is a conical structure. During stamping, the circular bottom wall and the annular side wall of the bowl-shaped blank are respectively abutted against the inner wall of the cavity of the outer die. The inner die is inserted into the bowl-shaped blank and clamps the circular bottom wall with the outer die. The positioning convex portion is inserted and engaged with the positioning hole to limit the rotation of the bowl-shaped blank. The punch pin penetrates the annular side wall from outside to inside to form a side hole.

7. The method for machining a crown-shaped bearing cage according to claim 6, wherein the inner die is driven by a servo motor to be rotatable. When the servo motor drives the inner die to rotate, the inner die synchronously drives the bowl-shaped blank to rotate within the cavity through the cooperation of the positioning convex portion and the positioning hole. During stamping, the servo motor drives the inner die and the bowl-shaped blank to rotate intermittently at a preset angle, so that the parts to be punched on the annular side wall are sequentially aligned with the punch pin, and the punch pin punches the side holes on the annular side wall in sequence.

8. The method for machining a crown-shaped bearing cage according to claim 1, wherein the S4 flanging side process uses a ball head spinning tool. The ball head spinning tool includes a spherical head that matches the flanging target curvature. During flanging, the spherical head rotates and advances from the inside to the outside on the inner side of the bowl-shaped blank towards the side hole, and radially folds the edge of the side hole to form a spherical pocket hole.

9. The method for machining a crown-shaped bearing cage according to claim 8, wherein in the S4 flanging side process, after the pocket hole is formed, a rolling strengthening process is added, and the inner wall of the pocket hole is rolled to cause plastic deformation of the material on the inner wall of the pocket hole.

10. The method for machining a crown-shaped bearing cage according to claim 1, wherein the S5 bottom cutting process uses a laser cutting process. The laser cutting process is specifically as follows: the laser cutting head cuts the middle area of the circular bottom wall along a preset circular path. During the cutting process, an inert gas is sprayed into the cutting area to cool the edge of the cut. After the cutting is completed, the cut is deburred.

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