Progressive die stamping forming process, die and product of rear end cover

Abstract

This invention relates to a progressive die stamping process for a rear end cover, characterized by the following sequential steps: S01 The strip material is fed in by a floating pin, the upper die assembly is guided downward by a precision ball bearing inner guide post and guide sleeve, the strip material is pressed down by the strip material under the action of the strip material back plate, and the guide pin punch punches guide pin holes through the strip material back plate and the strip material plate; S02 The cutting punch removes excess strip material and leaves an arc-shaped extension block outline, the arc-shaped extension block outline being located at a position offset from the window, forming an offset connecting material structure. In the forming operation of small windows, this invention simplifies the traditional three-step method of "punching + deep drawing + secondary punching" to a two-step method of "pre-punching + deep drawing", using finite element simulation to accurately predict material flow, avoiding secondary punching on the already formed inclined surface, reducing process difficulty, and simplifying the mold structure; in the forming operation of large windows, this invention adopts a two-step method of "first tearing laterally, then cutting laterally", first tearing and flattening the material.

Description

Technical Field

[0001] This invention belongs to the field of metal stamping technology, specifically relating to a progressive die stamping process, mold, and product for a rear end cap. Background Technology

[0002] As a common covering and positioning component in mechanical or electrical equipment, the rear end cover is usually stamped using progressive dies or single-operation dies. The finished rear end cover body often has multiple window structures for purposes such as installation of functional modules, wiring, heat dissipation, or positioning.

[0003] However, in terms of structural design, the windows of existing rear cover mostly adopt the same size specifications, or even if there are size differences, there is a lack of differentiated and modular layout considerations for different functional modules, which limits the integration and functional expandability of the rear cover in the whole machine.

[0004] Furthermore, in terms of forming process, regardless of whether the window size is the same, the existing process generally adopts a one-time punching method to complete the window forming. Simply put, the punching is performed directly on the curved surface or side wall after deep drawing or shaping. Due to the uneven force on the punch and the severe shearing of the material during the punching process, a large number of burrs are easily generated on the edge of the window, and even defects such as material brittleness and edge chipping are caused, which seriously affect the cross-sectional quality, structural strength and subsequent assembly accuracy of the product. In addition, the waste generated by one-time punching is irregular in shape, which can easily cause mold blockage, further affecting production efficiency and mold life. Summary of the Invention

[0005] To achieve the above objectives, the first aspect of the present invention provides a progressive die stamping process for a rear end cap, comprising the following steps performed sequentially:

[0006] S01 The strip is lifted and fed in by the floating pin. The upper mold assembly is guided downward by the precision ball inner guide post and guide sleeve. The stripper plate presses down on the strip under the action of the stripper plate back plate. The guide pin punch passes through the stripper plate back plate and the stripper plate to punch the guide pin hole.

[0007] S02 The cutting punch removes excess material strip and leaves an arc-shaped extension block outline. The arc-shaped extension block outline is located at a position that is offset from the window, forming an offset connecting material structure.

[0008] S03 pre-punching punch punches two small side windows in a plane.

[0009] S04 The tearing punch partially tears the strip in a predetermined area to facilitate material flow and deformation during deep drawing;

[0010] The S05 drawing punch assembly performs multiple drawing operations. During the first drawing, a nitrogen spring provides pressure to press the strip onto the strip, forming a lid-shaped body. At the same time, the pre-punched hole deforms into a small side window required for the product under the drawing action. The ejector pin and guide post help maintain the alignment accuracy between the upper and lower die assemblies during the drawing process. The unloading rod is used to balance local pressure.

[0011] S06 Shaping punch corrects the shape of the main body;

[0012] The S07 lateral tearing punch tears the large window area on the side. After tearing, it works with the lower template to flatten the torn part and preform the boundary outline of the large window.

[0013] The S08 side window punch punches out two large windows at once. During punching, the floating pin and the stripper plate together hold the workpiece to prevent deformation.

[0014] S09 Deburring punch removes burrs from the edges of windows;

[0015] The S10 forming punch shapes the bearing seat of the product. The bearing seat has a diameter of 13.5mm and is used for press-fitting the bearing.

[0016] S11 The cutting punch cuts off the jamming point between the workpiece and the material strip;

[0017] The S12 pre-cutting punch cuts upwards, leaving only a small connection between the workpiece and the strip.

[0018] After the S13 mold is opened, the upper mold assembly moves upward, the stripper plate separates from the workpiece, the feeder feeds forward one step, and the ejector punch set at the end of the lower mold plate cuts off the small number of connections, so that the workpiece is completely separated from the strip and the workpiece is ejected.

[0019] Preferably, the S03 pre-punching punch punches two small side windows in the pre-punching holes on the plane. The shape of the pre-punching holes is analyzed by AUTOFORM simulation and combined with the correction of the punching hole shape.

[0020] Preferably, the multiple drawing operations in S05 are five drawing operations, with the drawing depth increasing each time and the radius (R) angle gradually decreasing.

[0021] Preferably, the protrusion forming structure fixed in the upper mold assembly simultaneously forms the through protrusion at the top and the annular inner edge.

[0022] Preferably, the arc-shaped extension block outline reserved in S02 is gradually formed into an outwardly extending arc-shaped extension block by the arc-shaped forming structure fixed in the upper mold assembly and the lower mold assembly during the multiple drawing processes in S05 and the shaping process in S06.

[0023] A second aspect of the present invention provides a progressive die for implementing the progressive die stamping process, comprising an upper die assembly and a lower die assembly disposed opposite to each other:

[0024] The upper mold assembly includes: an upper mold base, an upper pad plate and an upper clamping plate fixedly below the upper mold base in sequence; a stripper plate backing plate is connected to the lower left side of the upper clamping plate via a hook, a stripper plate is fixedly connected to the lower part of the stripper plate backing plate, a nitrogen spring is installed between the upper mold base, the upper pad plate and the upper clamping plate, and a guide post is fixed on the upper mold base, the guide post passing through the upper pad plate, the upper clamping plate, the stripper plate backing plate and the stripper plate in sequence;

[0025] The lower mold assembly includes: a lower mold base, a lower back plate fixed to the lower mold base, a lower pad plate fixed to the lower back plate, and a lower template plate fixed to the lower pad plate; the lower template plate is provided with multiple lifting pins for supporting and floating the material strip; a lower pad block is provided below the lower mold base; ejector pins are provided on the lower mold base; and two sets of force relief rods are provided on the lower mold base; and...

[0026] The upper mold base is provided with a precision ball bearing inner guide post, and a guide sleeve that mates with the precision ball bearing inner guide post is provided between the lower mold plate and the lower pad.

[0027] Preferably, the upper die assembly is provided with multiple punches distributed at different workstations. The punches include: guide pin punch, cutting punch, pre-punching punch, tearing punch, drawing punch group, shaping punch, side tearing punch, side window punch, pressing punch, cutting point punch, pre-cutting punch, and part ejection punch.

[0028] A third aspect of the present invention provides a rear end cap product manufactured using a progressive die stamping process, comprising:

[0029] The main body is shaped like an inverted pot lid;

[0030] Multiple windows are arranged around the main body, including two large windows and two small windows. The two large windows are arranged opposite each other, and the two small windows are arranged opposite each other, with the large windows and small windows alternating.

[0031] An arc-shaped extension block is positioned offset from all the windows and extends outwards;

[0032] A protrusion is provided on the top of the main body, and the center of the protrusion is vertically continuous.

[0033] Preferably, there are four arc-shaped extension blocks, which are respectively arranged on both sides of the large window.

[0034] Preferably, the top of the protrusion extends inward to have an annular inner edge.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] The rear cover of this invention has two types of windows, large and small, arranged alternately, for connecting functional modules and running auxiliary lines, respectively, to realize modular assembly and functional expansion, significantly improving the integration of the whole machine and the convenience of maintenance. The top is provided with a cylindrical protrusion with an annular inner edge to realize axial limiting and sealing of bearings, shafts or cables, ensuring stable operation of moving or connected parts.

[0037] The progressive die of this invention uses precision ball bearing inner guide pillars, with the clearance controlled at the micrometer level, to achieve high guiding accuracy and wear resistance, ensuring consistency in small punches, windows and other workstations;

[0038] In the forming operation of small windows, this invention simplifies the traditional three-step method of "punching + drawing + secondary punching" to a two-step method of "pre-punching + drawing". It uses finite element simulation to accurately predict material flow, avoids secondary punching on the already formed inclined surface, reduces process difficulty, and simplifies mold structure.

[0039] The present invention adopts a two-step method of "first tearing laterally, then punching laterally" in the forming operation of large windows. First, the material is torn and flattened to pre-form the boundary and release stress, and then the final punching is completed, which significantly reduces burrs, tears and chipping, and improves the quality of the window cross section.

[0040] The large-window punching in this invention only removes a small amount of regular material bridges, and the waste is in a regular sheet shape without curling or deformation, which facilitates smooth discharge and avoids mold blockage.

[0041] The present invention employs a two-step separation process of "pre-cutting + cutting" during part production. First, it pre-cuts upward to retain a small number of connection points, and then cuts downward completely, which significantly reduces the burr height during final separation and improves the cross-sectional quality.

[0042] This invention achieves continuous stamping throughout the entire process by rationally arranging multiple punches, including guide pins, cutting, pre-punching, tearing, deep drawing, shaping, lateral tearing, side window punching, pressing, cutting point, pre-cutting, and part ejection, from flat sheet material to finished product rear end cover. This eliminates the need for intermediate handling or secondary positioning, significantly improving production efficiency and product consistency. Attached Figure Description

[0043] Figure 1 This is a three-dimensional structural diagram of the rear end cover in this invention;

[0044] Figure 2 This is a cross-sectional view of the rear end cover in this invention;

[0045] Figure 3 This is another perspective view of the rear end cover in this invention;

[0046] Figure 4 This is a diagram showing the mold opening state of the progressive die in this invention;

[0047] Figure 5 This is a diagram showing the mold closing state of the progressive die in this invention;

[0048] Figure 6 This is a schematic diagram showing the layout of each punch in this invention;

[0049] Figure 7 This is a flowchart of the preparation process of the present invention.

[0050] The diagram is labeled as follows: 1-Main body, 2-Large window, 3-Small window, 4-Arc-shaped extension block, 5-Protrusion, 6-Annular inner edge;

[0051] 10-Upper mold assembly, 101-Upper mold base, 102-Upper pad, 103-Upper clamping plate, 104-Hook, 105-Stripper plate back plate, 106-Stripper plate, 107-Nitrogen spring, 108-Guide post, 109-Precision ball inner guide post;

[0052] 11-Lower mold assembly, 111-Lower mold base, 112-Lower back plate, 113-Lower pad plate, 114-Lower template, 115-Floating pin, 116-Lower pad block, 117-Ejector pin, 118-Unloading rod, 119-Guide sleeve;

[0053] 20-Guide pin punch, 21-Cutting punch, 22-Pre-punching punch, 23-Tearing punch, 24-Drawing punch set, 25-Shaping punch, 26-Side tearing punch, 27-Side window punch, 28-Flash pressing punch, 29-Flash pressing and shaping punch, 30-Cut point punch, 31-Pre-cutting punch, 32-Ejection punch. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Example 1

[0056] like Figures 1 to 3The rear end cover shown is manufactured using a progressive die stamping process. It includes a main body 1, which is shaped like an inverted pot lid and primarily serves to cover, position, and protect internal components while also withstanding certain mechanical loads and environmental influences. It can be made of high-strength stainless steel, galvanized steel sheet, or aluminum alloy sheet, all of which have good stamping performance. The main body 1 has two large windows 2 and two small windows 3 arranged circumferentially. The two large windows 2 are positioned opposite each other, and the two small windows 3 are also positioned opposite each other, with the large windows 2 and small windows 3 alternating. The large windows 2 are used for functional modules or connector interfaces to pass through, enabling external connection and heat dissipation for electrical or mechanical components. The small windows 3 are used for auxiliary circuits, positioning pins, or detection... The probes pass through, and the two work together to achieve modular assembly and functional expansion, improving the integration and maintenance convenience of the rear cover in the whole machine; the main body 1 has an arc-shaped extension block 4 located at the position where the windows are staggered and near the large window 2, which is mainly used to enhance the local structural strength, provide lateral mounting ears or fix wire harness buckles, and optimize stress distribution without increasing the overall outline, avoiding cracks during the stamping process; the top of the main body 1 has a cylindrical protrusion 5, which is used to accommodate the passage and positioning of bearings, shafts or cable harnesses, and the top of the protrusion 5 extends inward with an annular inner edge, which is used to axially limit, prevent detachment or seal the parts passing through the protrusion 5, and ensure the stable operation of moving or connected parts.

[0057] Example 2

[0058] like Figures 4 to 6 The progressive die for preparing a rear end cap includes an upper die assembly 10 and a lower die assembly 11 arranged opposite to each other. Through the continuous closing and opening operations of the upper die assembly 10 and the lower die assembly 11, the strip is sequentially subjected to processes such as punching, drawing, forming, shaping, punching, and separation, so as to achieve continuous, efficient and high-precision preparation of the rear end cap.

[0059] The upper mold assembly 10 includes: an upper mold base 101, an upper pad 102 and an upper clamping plate 103 fixedly below the upper mold base 101 in sequence. The upper pad 102 is used to buffer the stamping reaction force, and the upper clamping plate 103 is used to fix various punches and inserts. A stripper plate 106 back plate 105 is connected to the lower left side of the upper clamping plate 103 via a hook 104. The stripper plate 106 is fixedly connected below the back plate 105. The stripper plate 106 peels the strip from the punch when the mold is opened, preventing the strip from sticking to the upper mold. The hook 104 provides suspension and limiting functions, and also allows the stripper plate 106 to be compressed and floated relative to the upper clamping plate 103 when the mold is closed.

[0060] A nitrogen spring 107 is installed between the upper die holder 101, the upper pad 102, and the upper clamping plate 103. The piston rod of the nitrogen spring 107 acts on the back plate 105 or the stripper plate 106 to provide a stable, balanced, and adjustable pressing force. Compared with ordinary springs, the nitrogen spring 107 has the characteristics of large initial pressure, small pressure change during the stroke, and long fatigue life. It can maintain the pressing state of the stripper plate 106 on the strip at all times during high-speed stamping, which significantly improves the forming accuracy and mold stability.

[0061] The lower die assembly 11 includes: a lower die base 111, a lower back plate 112 fixed on the lower die base 111, a lower pad plate 113 fixed on the lower back plate 112, and a lower template 114 fixed on the lower pad plate 113; wherein, the lower back plate 112 and the lower pad plate 113 jointly bear the stamping load to prevent the lower template 114 from collapsing or deforming locally, and the lower template 114 is provided with a plurality of lifting pins 115 for supporting and floating the strip material to ensure that the strip material is lifted smoothly and fed smoothly between processes, avoiding scratches or jamming; a lower pad block 116 is provided below the lower die base 111 to raise the lower die assembly 11 to adapt to the closing height of the punch press and to provide material discharge space for the lower die.

[0062] As described above, a guide post 108 is fixed on the upper mold base 101. The guide post 108 passes through the upper pad 102, the upper clamping plate 103, the stripper plate 106, the back plate 105, and the stripper plate 106 in sequence. It is used to ensure that the upper mold assembly 10 is aligned with the lower mold assembly 11 during the movement and to prevent off-center loading. Correspondingly, an ejector pin 117 is also provided on the lower mold base 111 to eject the stamped workpiece or waste material from the lower mold when the mold is opened, so as to facilitate material dropping or blowing out.

[0063] The lower die holder 111 is equipped with two sets of stress relief rods 118. One set of stress relief rods 118 is located below the horizontal position of the drawing punch group 24. During the drawing process, it absorbs the peak impact load and prevents the drawing punch from hard impacting the lower die, which could lead to chipping or breakage. The other set is located below the horizontal position of the forming punch 25. During the forming process, it balances the local back pressure and avoids the forming punch 25 from generating excessive reverse deformation force on the strip, thus ensuring dimensional stability after forming. Both sets of stress relief rods 118 can be made of polyurethane columns and their stiffness can be adjusted independently according to the stamping load.

[0064] Furthermore, the precision ball bearing inner guide post 108 adopts a ball cage structure, with the clearance controlled at the micron level. This enables extremely high guiding accuracy and wear resistance during high-speed stamping, significantly reducing the relative runout between the upper and lower dies, thereby ensuring the forming consistency of precision stations such as small punches, irregular windows, and lateral tearing.

[0065] Furthermore, the upper die assembly 10 is provided with multiple punches, which are distributed at different workstations and arranged sequentially according to the material feeding direction. The punches include:

[0066] A guide pin punch 20 is used to punch guide holes on the strip material and cooperate with guide pins to achieve precise positioning between each station; a cutting punch 21 is used to rough cut the shape of the strip material, determine the boundary of the process step, and reduce the material flow resistance during subsequent forming; a pre-punching punch 22 is used to pre-punch small windows 3 before deep drawing; a tearing punch 23 is used to locally tear specific areas to form material separation or pre-forming features, creating conditions for subsequent window forming; a deep drawing punch group 24 includes multiple steps or different diameters to gradually draw the flat strip material into a pre-formed shape of a lid-shaped main body 1 and a cylindrical protrusion 5; a shaping punch 25 is used to refine the outline, bottom rounded corners, and protrusion 5 features of the deep-drawn main body 1, correct springback, and ensure dimensional accuracy; A lateral tearing punch 2623, using a wedge structure, performs tearing or cutting action on the side of the strip to form a pre-opening or separation area for the window; a side window punch 27, in conjunction with a wedge drive mechanism, punches the window area to ultimately form the complete outline of the large window 2; a burr-flattening punch 28, used to flatten or trim burrs and flashes generated after punching or tearing, improving the surface quality of the window and edges; a cutting point punch 30, used to cut at the connection point between the workpiece and the strip, separating the workpiece from the strip; a pre-cutting punch 31, used to pre-separate or partially cut the outer edge of the workpiece before final ejection, reducing the impact load on the ejection punch; and an ejection punch that completely punches the rear end cap workpiece, after all processes have been completed, out of the strip. 32

[0067] In summary, through the reasonable arrangement and coordinated work of each punch, the progressive die in this embodiment can complete the entire stamping process from flat material to the final rear end cover in one feeding process, without the need for intermediate handling or secondary positioning, which greatly improves production efficiency and product consistency.

[0068] Example 3

[0069] like Figures 1 to 7 The progressive die stamping process shown includes the following steps performed sequentially:

[0070] S01 The strip is lifted and fed in by the floating pin 115. The upper mold assembly 10 is guided downward by the precision ball inner guide post 108 and the guide sleeve. The stripper plate 106 presses the strip under the action of the stripper plate 106 back plate 105. The guide pin punch 20 passes through the stripper plate 106 back plate 105 and stripper plate 106 to punch guide pin holes.

[0071] S02 The cutting punch 21 removes excess material strip and leaves the outline of the arc-shaped extension block 4. The outline of the arc-shaped extension block 4 is located at a position that is offset from the window, forming an offset connecting material structure.

[0072] S03 Pre-punching punch 22 punches two small side windows in a plane.

[0073] S04 Tear punch 23 partially tears the strip in a predetermined area to facilitate material flow and deformation during deep drawing;

[0074] S05 The deep drawing punch assembly 24 performs multiple deep drawing operations. During the first deep drawing, the nitrogen spring 107 provides a pressure force to make the stripping plate 106 press the strip to form a pot lid-shaped body 1. At the same time, the pre-punched hole is deformed into a small side window required by the product under the deep drawing action. The ejector pin 117 and the guide post 108 help maintain the alignment accuracy of the upper die assembly 10 and the lower die assembly 11 during the deep drawing process. The unloading rod 118 is used to balance local pressure.

[0075] S06 Shaping punch 25 corrects the shape of body 1;

[0076] S07 Lateral tearing punch 2623 performs lateral tearing on the side window 2 area. After tearing, it cooperates with the lower template 114 to flatten the torn part and preform the boundary contour of the large window 2.

[0077] S08 The side window punch 27 punches out two large windows 2 at once. During punching, the floating pin 115 and the stripper plate 106 together clamp the workpiece to prevent deformation.

[0078] S09 Deburring punch 28 removes burrs from window edges;

[0079] The S10 forming punch 25 shapes the bearing seat of the product, which has a diameter of 13.5mm and is used for press-fitting the bearing.

[0080] S11 The 30-point cutting punch cuts off the jamming point between the workpiece and the material strip;

[0081] S12 pre-cutting punch 31 punches upwards, leaving only a small amount of connection between the workpiece and the strip;

[0082] After the mold opens (S13), the upper mold assembly 10 moves upward, the stripper plate 106 separates from the workpiece, the feeder feeds forward one step, and the ejector punch at the end of the lower mold plate 114 cuts off the small number of connections, so that the workpiece is completely separated from the strip and the workpiece is ejected.

[0083] Example 4

[0084] like Figures 1 to 7The progressive die stamping process for manufacturing a rear end cap is shown. Specifically, the metal strip is lifted and fed into the stamping area by the floating pin 115. The upper die assembly 10 is driven by the press slide and guided smoothly downward by the precision ball inner guide post 108 and the guide sleeve. The stripper plate 106 is driven by the stripper plate 106 back plate 105 to contact and press the strip first. Then, the guide pin punch 20 passes through the stripper plate 106 back plate 105 and the stripper plate 106 to precisely punch guide pin holes on the strip, ensuring the step accuracy of subsequent processes.

[0085] The cutting punch 21 removes the excess portion on both sides of the strip while reserving the outline of the arc-shaped extension block 4. This outline is located at a position that is offset from all windows, forming a "staggered connecting structure". This structure can significantly reduce waste generation, improve material utilization, and ensure the overall stability of the strip during the deep drawing process.

[0086] The pre-punching punch 22 punches two small side windows on a flat surface. It should be noted that in traditional processes, after deep drawing, a second punching is often performed on the windows on the sidewalls or inclined surfaces. At this time, the punch is subjected to uneven force and is difficult to position, which can easily produce burrs, deformation, or even cracks. This embodiment simplifies the traditional three-step method of "punching + deep drawing + secondary punching" into a two-step method of "pre-punching + deep drawing", reducing the number of processes and mold stations. By using the AUTOFORM finite element simulation analysis system, the flow law, thickness distribution change, and stress-strain path of the material in the subsequent deep drawing process are simulated to accurately predict the morphological evolution trend of the pre-punched holes after three-dimensional deformation. This ensures that after multiple deep drawing processes, the pre-punched holes can naturally extend, stretch, and finally form the target shape of the small side windows required by the product. The complex process of secondary punching on the already formed inclined or curved surface in the prior art is moved forward and transformed into a pre-punching operation in a flat state, thereby avoiding secondary punching on the already formed inclined surface, reducing the process difficulty, and simplifying the mold structure.

[0087] The tearing punch 23 tears the material strip in a predetermined area, releasing local stress concentration during the deep drawing process through controlled material separation, thereby guiding the material to flow orderly into the deep drawing area and reducing the risk of tearing or wrinkling.

[0088] The drawing punch assembly 24 performs multiple drawing operations, specifically five times, with each drawing depth increasing and the radius (R) angle gradually decreasing. During the first drawing operation, the nitrogen spring 107 provides a stable clamping force, causing the stripper plate 106 to tightly press the strip, initially forming the lid-shaped main body 1. Simultaneously, the aforementioned pre-punched holes gradually deform into the small side windows required for the product under circumferential tensile stress. The ejector pin 117 and guide post 108 assist in maintaining the alignment accuracy of the upper and lower dies during this process, while the unloading rod 118 is used to balance the off-center load caused by material thickness fluctuations or local pressure differences.

[0089] Furthermore, during the second drawing process, the protrusion 5 forming structure fixed in the upper die assembly 10 works synchronously to form the through protrusion 5 at the top and the annular inner edge, providing a basis for subsequent bearing seat shaping.

[0090] Example 5

[0091] like Figures 1 to 7 The progressive die stamping process for preparing the rear end cover is shown. It should be noted that the existing technology for punching the large window 2 mainly adopts the method of first punching and then drawing, or vertical punching on the already formed side wall. The former will cause severe deformation of the window; the latter has a complex mold structure, is difficult to remove waste, and is prone to tearing and burrs. Therefore, this embodiment adopts a two-step method of first tearing laterally and then punching laterally. The tearing process is used to pre-form and release stress, so as to achieve high-quality and low-burr window forming.

[0092] Specifically, the lateral tearing punch 2623 tears the side window 2 area laterally, and immediately cooperates with the lower template 114 to flatten the flipped material, pre-forming the boundary contour of the large window 2, providing a flat and tear-free boundary condition for subsequent complete punching of the window; the side window punch 27 punches out two large windows 2 at once. During the punching process, the floating pin 115 and the stripper plate 106 jointly clamp the workpiece to prevent deformation of the workpiece due to the punching force; the burr-removing punch 28 then removes the burrs and burrs remaining on the edge of the window; the shaping punch 25 precisely shapes the bearing position of the product, with a final diameter of 13.5mm, for subsequent bearing pressing and riveting; the clamping punch 30 cuts the clamping point between the workpiece and the strip, achieving partial separation.

[0093] In other words, S08 is a side punching process performed on the side wall after stress relief and boundary preforming, following the pretreatment of S07. Although the side punching structure is used, S07 takes on the main work, and S08 has a smaller punching force and a longer die life. During this process, the floating pin 115 and the stripper plate 106 are clamped together at the moment of punching, providing strong local support for the inner and outer surfaces of the workpiece to prevent deformation. Finally, a rear end cover with small burrs and high window precision is obtained.

[0094] Moreover, since the S07 tearing process has pre-separated most of the material at the window boundary and flattened the flange, S08 only needs to remove a small amount of connecting material bridges. Therefore, the waste generated is small and regular geometric pieces with regular contours and no curling or deformation. It can be smoothly discharged through the waste hole of the lower mold, effectively avoiding mold failure caused by waste blockage.

[0095] Subsequently, the pre-cutting punch 31 adopts an upward punching structure, punching from bottom to top, so that the workpiece and the strip retain only a few connection points. This design of pre-cutting first and then cutting can significantly reduce the burr height during final separation and improve the cross-sectional quality.

[0096] After the mold is opened, the upper mold assembly 10 moves upward, the stripper plate 106 automatically separates from the workpiece, the feeder moves forward one step, and the part ejector punch set at the end of the lower mold plate 114 adopts a downward cutting structure to cut off the small number of connection points remaining after pre-cutting in one go, so that the workpiece is completely separated from the strip, and the part is ejected by gravity or air blowing, completing the entire progressive stamping process.

[0097] Example 6

[0098] In the above-mentioned S02, the arc-shaped extension block 4 outline reserved is formed by the arc-shaped forming structure fixed in the upper mold assembly 10 and the corresponding insert of the lower mold assembly 11 gradually cooperating and forming during the multiple drawing processes in S05 and the shaping process in S06. Finally, an arc-shaped extension block 4 that extends stably to the outside is formed, which serves as a material carrier and is also retained as a functional or assembly structural feature in the finished product.

[0099] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0100] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A progressive die stamping process for a rear end cap, characterized in that, The following steps are performed sequentially: S01 The strip is lifted and fed in by the floating pin. The upper mold assembly is guided downward by the precision ball inner guide post and guide sleeve. The stripper plate presses down on the strip under the action of the stripper plate back plate. The guide pin punch passes through the stripper plate back plate and the stripper plate to punch the guide pin hole. S02 The cutting punch removes excess material strip and leaves an arc-shaped extension block outline. The arc-shaped extension block outline is located at a position that is offset from the window, forming an offset connecting material structure. S03 pre-punching punch punches two small side windows in a plane. S04 The tearing punch partially tears the strip in a predetermined area to facilitate material flow and deformation during deep drawing; The S05 drawing punch assembly performs multiple drawing operations. During the first drawing, a nitrogen spring provides pressure to press the strip onto the strip, forming a lid-shaped body. At the same time, the pre-punched hole deforms into a small side window required for the product under the drawing action. The ejector pin and guide post help maintain the alignment accuracy between the upper and lower die assemblies during the drawing process. The unloading rod is used to balance local pressure. S06 Shaping punch corrects the shape of the main body; The S07 lateral tearing punch tears the large window area on the side. After tearing, it works with the lower template to flatten the torn part and preform the boundary outline of the large window. The S08 side window punch punches out two large windows at once. During punching, the floating pin and the stripper plate together hold the workpiece to prevent deformation. S09 Deburring punch removes burrs from the edges of windows; The S10 forming punch shapes the bearing seat of the product. The bearing seat has a diameter of 13.5mm and is used for press-fitting the bearing. S11 The cutting punch cuts off the jamming point between the workpiece and the material strip; The S12 pre-cutting punch cuts upwards, leaving only a small connection between the workpiece and the strip. After the S13 mold is opened, the upper mold assembly moves upward, the stripper plate separates from the workpiece, the feeder feeds forward one step, and the ejector punch set at the end of the lower mold plate cuts off the small number of connections, so that the workpiece is completely separated from the strip and the workpiece is ejected.

2. The progressive die stamping process according to claim 1, characterized in that, The S03 pre-punching punch punches two small side windows in the pre-punching holes on the plane. The shape of the pre-punching holes is analyzed by AUTOFORM simulation and combined with the correction of the punching hole shape.

3. The progressive die stamping process according to claim 1, characterized in that, The multiple drawing operations mentioned in S05 refer to five drawing operations, with the drawing depth increasing each time and the radius (R) angle gradually decreasing.

4. The progressive die stamping process according to claim 1, characterized in that, During the second drawing process, the protrusion forming structure fixed in the upper die assembly simultaneously forms the through protrusion at the top and the annular inner edge in S05.

5. The progressive die stamping process according to claim 1, characterized in that, The arc-shaped extension block outline reserved in S02 is gradually formed into an outwardly extending arc-shaped extension block by the arc-shaped forming structure fixed in the upper mold assembly and the lower mold assembly during the multiple drawing processes in S05 and the shaping process in S06.

6. A progressive die for implementing the method of any one of claims 1-5, comprising an upper die assembly and a lower die assembly disposed opposite to each other, characterized in that: The upper mold assembly includes: an upper mold base, an upper pad plate and an upper clamping plate fixedly below the upper mold base in sequence; a stripper plate backing plate is connected to the lower left side of the upper clamping plate via a hook, a stripper plate is fixedly connected to the lower part of the stripper plate backing plate, a nitrogen spring is installed between the upper mold base, the upper pad plate and the upper clamping plate, and a guide post is fixed on the upper mold base, the guide post passing through the upper pad plate, the upper clamping plate, the stripper plate backing plate and the stripper plate in sequence; The lower mold assembly includes: a lower mold base, a lower back plate fixed to the lower mold base, a lower pad plate fixed to the lower back plate, and a lower template plate fixed to the lower pad plate; the lower template plate is provided with multiple lifting pins for supporting and floating the material strip; a lower pad block is provided below the lower mold base; ejector pins are provided on the lower mold base; and two sets of force relief rods are provided on the lower mold base; and... The upper mold base is provided with a precision ball bearing inner guide post, and a guide sleeve that mates with the precision ball bearing inner guide post is provided between the lower mold plate and the lower pad.

7. The progressive die stamping die according to claim 6, characterized in that, The upper die assembly is equipped with multiple punches distributed at different workstations. The punches include: guide pin punch, cutting punch, pre-punching punch, tearing punch, drawing punch group, shaping punch, side tearing punch, side window punch, burr pressing punch, snipping punch, pre-cutting punch, and part ejection punch.

8. A rear end cap product manufactured using the method described in any one of claims 1-5, characterized in that, include: The main body is shaped like an inverted pot lid; Multiple windows are arranged around the main body, including two large windows and two small windows. The two large windows are arranged opposite each other, and the two small windows are arranged opposite each other, with the large windows and small windows alternating. An arc-shaped extension block is positioned offset from all the windows and extends outwards; A protrusion is provided on the top of the main body, and the center of the protrusion is vertically continuous.

9. The rear end cover according to claim 8, characterized in that, There are four arc-shaped extension blocks, which are respectively set on both sides of the large window.

10. The rear end cover according to claim 8, characterized in that, The top of the protrusion extends inward and has an annular inner edge.

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