Cold heading die set for a seat swivel pin

Abstract

The utility model discloses a cold heading die set for seat rotating pin, including material breaking subassembly and five groups of cold heading die, first cold heading die forms double -end conical surface and chamfer, second cold heading die transforms conical surface into circular table, third cold heading die processes multistage conical table and cylinder end, fourth cold heading die forms convex and diameter -enlarging conical table, fifth cold heading die completes end circular table, arc groove, convex part and chamfer part. Adopt multistation stage cold heading, avoid single -time deformation too big, through die, die cavity and forming feature accurate matching control tolerance, realize complex structure high -precision forming, need not secondary processing, improve material utilization and product mechanical performance, guarantee batch production consistency.

Description

Technical Field

[0001] This utility model relates to the technical field of cold heading mold assembly, specifically to a cold heading mold assembly for a seat rotating pin. Background Technology

[0002] Seat swivel pins are crucial connecting components in products such as automobiles and office chairs, enabling seat angle adjustment and locking functions. To meet complex assembly and functional requirements, these swivel pins are often designed with irregular shapes such as multi-steps, conical surfaces, and non-circular ends. Manufacturing these irregular structures using traditional machining methods like turning and milling suffers from low material utilization, low production efficiency, and the risk of cutting away metal flow lines, leading to reduced product fatigue strength. Therefore, a technical solution is urgently needed that can improve production efficiency and save costs while ensuring product quality. Utility Model Content

[0003] Purpose of the utility model: In order to overcome the above shortcomings, the purpose of this utility model is to provide a cold heading mold assembly for seat rotating pins, which gradually forms the complex geometric features of the rotating pins through a multi-station cold heading process, thereby achieving efficient and high-precision production, while improving material utilization and product mechanical properties.

[0004] Technical Solution: This utility model provides a cold heading die assembly for a seat rotating pin, comprising: a first cold heading die, which is used to cold head a cylindrical blank into a first cold heading part; at a first end of the first cold heading part along its axial direction, a first conical surface is formed by cold heading using the first cold heading die, and the first conical surface and the side surface of the cylinder are transitioned through a chamfer structure; at the other end of the first cold heading part along its axial direction, a second conical surface and a third conical surface are formed by cold heading using the first cold heading die and are coaxially connected in sequence, and the second conical surface and the third conical surface are smoothly connected through a conical surface. The system comprises: a first cold-forged part and a second cold-forged part; a second cold-forged die, used to cold-forge the first conical surface into a first frustum, and cold-forging the second and third conical surfaces into frustums of cones; and a third cold-forged die, used to cold-forge the second cold-forged part into a third cold-forged part, used to cold-forge the first frustum into a cylindrical end, a second frustum of cone, a third frustum of cone, and a fourth frustum of cone, arranged sequentially from top to bottom, with the lower end face of the cylindrical end connected to the small base face of the second frustum of cone. The large base of the second truncated cone is connected to the small base of the third truncated cone, the large base of the third truncated cone is connected to the large base of the fourth truncated cone, and the small base of the fourth truncated cone is connected to the central cylinder of the third cold-forged part; a fourth cold-forging die is used to cold-forge the third cold-forged part into a fourth cold-forged part, the fourth cold-forging die cold-forges the cylindrical end and the second truncated cone into a first protrusion, cold-forges the third truncated cone into a fifth truncated cone, the diameter of the large base of the fifth truncated cone is larger than the diameter of the large base of the third truncated cone, cold-forges the fourth truncated cone into a sixth truncated cone, the fifth truncated cone... The large base of the platform is connected to the large base of the sixth truncated cone, the diameter of the large base of the sixth truncated cone is larger than the diameter of the large base of the fourth truncated cone, and the small base of the sixth truncated cone is connected to the central cylinder of the fourth cold-forged part; the fifth cold-forging die is used to cold-forge the fourth cold-forged part into a finished product, the fifth cold-forging die cold-forges the first protrusion, the fifth truncated cone, and the sixth truncated cone into end truncated cones, wherein the upper surface of the end truncated cone is cold-forged into three arc grooves along the outer edge, the upper surface of the end truncated cone is cold-forged into the first protrusion and the second protrusion, and the small base of the truncated cone is cold-forged into a chamfered part. The process employs a phased cold heading process, with each step focusing on optimizing only the local structure. This avoids excessive deformation during a single processing step and allows for precise control of dimensional tolerances for features such as truncated cones, cylindrical ends, and arc grooves. It is suitable for ensuring product consistency during mass production. All structures are directly formed through cold heading, eliminating the need for additional secondary processing such as cutting and grinding, thus shortening the production process and reducing material waste.

[0005] Furthermore, a cold heading die assembly for a seat rotating pin according to this application further includes a cutting assembly, which comprises a cutting seat with an upper opening and a cutting part. The cutting seat has a cutting cavity for accommodating the bar stock, and the cutting part is used to cut the bar stock in the cutting cavity into cylindrical blanks. The cutting cavity has a radial limiting effect on the bar stock, and in conjunction with the cutting part, cuts the bar stock into cylindrical blanks of a fixed length.

[0006] Furthermore, in this application, a cold heading die assembly for a seat rotating pin includes a first upper die and a first lower die. The first upper die is disposed above the first lower die. The first upper die includes a first upper die shell, on which a first upper punch is disposed. The shape of the end of the first upper punch near the first lower die corresponds to the upper end face of the first cold-headed part. A first upper die core is embedded in the side of the first upper die shell near the first lower die. The first upper die core is sleeved on the first upper punch, and a first upper die core cavity is provided on the first upper die core. The shape of the upper part of the side wall of the cavity corresponds to the first conical surface; the first lower die includes a first lower die shell, on which a first lower punch is provided, the first lower punch is positioned directly opposite the first upper punch, the shape of the end of the first lower punch near the first upper die corresponds to the lower end face of the first cold-forged part, a first lower die core is provided on the side of the first lower die shell near the first upper die, the first lower punch is provided on the first lower die core, a first lower die core cavity is provided on the first lower die core, and the shape of the bottom of the side wall of the first lower die core cavity corresponds to the second conical surface and the third conical surface. The shape of the end of the first upper punch near the lower die perfectly corresponds to the upper surface of the first cold-forged part, directly acting on the upper surface of the blank to cold-forge it into a shape that conforms to the design. The upper die core is embedded in the upper die shell and fitted outside the first upper punch. The upper part of the cavity sidewall precisely matches the first conical surface of the first cold-forged part, constraining the deformation direction of the upper side of the blank during cold forging, ensuring the formation of the first conical surface, and ensuring precise chamfer transition between the first conical surface and the cylindrical side through the cavity structure. The first lower punch... The head is positioned directly opposite the first upper punch, with the shape of its end near the upper die corresponding to the lower end face of the first cold-forged part. It forms an upper and lower pressure with the upper punch, and directly shapes the lower end face of the blank. The lower die core is located on the side of the lower die shell near the upper die, and the first lower punch passes through it. The shape of the bottom of the side wall of its cavity matches the second and third conical surfaces of the first cold-forged part, constraining the deformation of the lower side of the blank, ensuring the coaxiality of the two conical surfaces and the smooth transition of the conical surface, and providing a precise basic blank shape for the subsequent cold-forging process.

[0007] Furthermore, in this application, a cold heading die assembly for a seat rotating pin includes a second cold heading die comprising a second upper die and a second lower die. The second upper die is disposed above the second lower die and includes a second upper die shell. A second upper punch is disposed on the second upper die shell, and the shape of the end of the second upper punch near the second lower die corresponds to the upper end face of the second cold-headed part. The second lower die includes a second lower die shell, and a second lower punch is disposed on the second lower die shell, with the second lower punch positioned directly opposite the second upper punch. The shape of the head near the second upper die corresponds to the lower end face of the second cold-forged part. A second lower die core A is provided on the side of the second lower die shell near the second upper die, and a second lower die core A cavity is provided on the second lower die core A. The second cold-forged part passes through the second lower die core A cavity. The shape of the middle side wall of the second lower die core A cavity corresponds to the side ring surface of the first frustum. A second lower die core B is provided below the second lower die core A, and a second lower die core B cavity is provided on the second lower die core B. The bottom shape of the side wall of the second lower die core B cavity corresponds to the frustum of a cone. The second lower die core A and its cavity A are located on the side of the lower die shell near the upper die, and the shape of the middle side wall of its cavity precisely matches the side ring surface of the first frustum of a cone of the second cold-forged part. When the first cold-forged part enters cavity A, the sidewall in the middle of cavity A constrains the deformation of the upper side of the blank, transforming the original first conical surface cold-forging into a regular first truncated cone. This ensures the critical dimensions of the truncated cone, such as its taper and diameter. The second lower die core B and cavity B are located below cavity A. The bottom shape of its cavity sidewall corresponds to the truncated cone of the second cold-forged part, constraining the deformation of the lower side of the blank. This integrates the original combination of the second and third conical surfaces of the first cold-forged part into a single truncated cone, ensuring its coaxiality and smooth connection with the upper first truncated cone. The second lower punch is positioned directly opposite the second upper punch. The shape of its end near the upper die corresponds to the lower end face of the second cold-forged part, creating an upward and downward pressure with the upper punch. This provides the necessary pressure for cold forging and directly shapes the lower end face of the blank, ensuring structural matching between the lower end face and the truncated cone.

[0008] Furthermore, in this application, a cold heading die assembly for a seat rotating pin includes a third cold heading die comprising a third upper die and a third lower die. The third upper die is disposed above the third lower die. The third upper die includes a third upper die shell, on which a third upper punch is inserted. The shape of the end of the third upper punch near the third lower die corresponds to the upper end face of the third cold-headed part. A third upper die core is embedded on the side of the third upper die shell near the third lower die. The third upper die core is fitted onto the third upper punch, and the shape of the end of the third upper die core near the third upper punch corresponds to the cylindrical end. A third upper die cavity is provided on the third upper die core, and the shape of the middle part of the side wall of the third upper die cavity corresponds to the shape of a second truncated cone. Correspondingly, the shape of the lower part of the side wall of the third upper mold cavity where it connects with the third lower mold corresponds to the third truncated cone; the third lower mold includes a third lower mold shell, on which a third lower punch is inserted, the third lower punch being positioned directly opposite the third upper punch, the shape of the end of the third lower punch near the third upper mold corresponding to the lower end face of the third cold-forged part, a third lower mold core is provided on the side of the third lower mold shell near the third upper mold, the third lower punch is inserted on the third lower mold core, a third lower mold core cavity is provided on the third lower mold core, the shape of the upper part of the side wall of the third lower mold core cavity where it connects with the upper mold corresponds to the fourth truncated cone, and the shape of the bottom of the side wall of the third lower mold core cavity corresponds to the truncated cone.The third upper punch is inserted into the third upper die shell. Its end near the lower die corresponds perfectly to the upper surface of the third cold-forged part, directly acting on the upper surface of the blank. Cold forging forms the designed upper surface shape and provides pressure support for the upper structure. The third upper die core is embedded in the upper die shell near the lower die and fitted onto the outside of the third upper punch. Its shape near the punch end precisely matches the cylindrical end, directly constraining the deformation of the top of the blank during cold forging, ensuring the dimensional accuracy of the cylindrical end's diameter, height, etc. The shape of the middle part of the side wall of the third upper die cavity corresponds to the second truncated cone, constraining the deformation of the upper side of the blank and cold-forging the corresponding area into a second truncated cone with a preset taper. The shape of the lower part of the side wall where it connects to the lower die corresponds to the third truncated cone, further constraining the deformation of the middle side of the blank, forming the third truncated cone, and ensuring its connection with the second truncated cone (the large base of the second truncated cone connects to the small base of the third truncated cone). The third lower punch is positioned directly opposite the third upper punch, passing through the third lower die shell and the third lower die core. The shape of its end near the upper die corresponds to the lower end face of the third cold-forged part, forming an upper and lower pressure with the upper punch. This provides cold-forging pressure and directly shapes the lower end face of the blank, ensuring the matching of the lower end face with the bottom structure. The third lower die core and its cavity are located on the side of the lower die shell near the upper die. The shape of the upper part of its cavity sidewall, where it connects with the upper die, corresponds to the fourth truncated cone, constraining the deformation of the lower side of the blank to form the fourth truncated cone and ensuring its connection with the third truncated cone (the large bottom surface of the third truncated cone connects with the large bottom surface of the fourth truncated cone). The shape of the bottom of the cavity sidewall corresponds to the truncated cone (supported by the basic structure of the second cold-forged part), limiting the lower part of the blank and ensuring the stability of the overall structure.

[0009] Furthermore, in this application, a cold heading die assembly for a seat rotating pin includes a fourth cold heading die comprising a fourth upper die and a fourth lower die. The fourth upper die is disposed above the fourth lower die. The fourth upper die includes a fourth upper die shell, on which a fourth upper punch is inserted. The shape of the end of the fourth upper punch near the fourth lower die corresponds to the upper end face of the fourth cold-headed part. A fourth upper die core is embedded on the side of the fourth upper die shell near the fourth lower die. The fourth upper die core is fitted onto the fourth upper punch. The fourth upper die core has a fourth upper die cavity. The sidewall shape of the fourth upper die cavity corresponds to the first protrusion. The lower part of the sidewall of the fourth upper die cavity... The shape of the part that connects with the fourth lower die corresponds to the shape of the fourth cold-forged part; the fourth lower die includes a fourth lower die shell, on which a fourth lower punch is provided. The fourth lower punch is positioned directly opposite the fourth upper punch. The shape of the end of the fourth lower punch near the fourth upper die corresponds to the lower end face of the fourth cold-forged part. A fourth lower die core is provided on the side of the fourth lower die shell near the fourth lower die. The fourth lower punch passes through the fourth lower die core. A fourth die core cavity is provided on the fourth lower die core. The shape of the bottom side wall of the fourth die core cavity corresponds to a truncated cone. The shape of the upper part of the side wall of the fourth die core cavity where it connects with the fourth upper die corresponds to a sixth truncated cone. The fourth upper punch passes through the fourth upper die shell. Its end near the lower die perfectly corresponds to the upper surface of the fourth cold-forged part, directly acting on the upper surface of the blank. Under cold-forging pressure, it shapes the upper surface and provides pressure support for the deformation of the upper structure. The fourth upper die core is embedded in the upper die shell near the lower die and fitted onto the outside of the fourth upper punch. The shape of its chamber sidewall precisely matches the first protrusion. During cold forging, the chamber sidewall constrains the upper part of the blank (the cylindrical end of the original third cold-forged part + ...). The deformation direction of the second truncated cone is used to integrate it into a single first protrusion during cold forging, ensuring the protrusion's contour, size, and surface flatness. The lower part of the upper mold cavity sidewall, where it connects to the lower mold, matches the corresponding area of ​​the fourth cold-forged part, forming a connection point with upper and lower constraints. This ensures the coaxiality and connection stability of the first protrusion and the lower structure (fifth truncated cone). The fourth lower punch is positioned directly opposite the fourth upper punch, passing through the fourth lower mold shell and the fourth lower mold core. Its end near the upper mold corresponds to the lower end face of the fourth cold-forged part, forming an upper and lower pressure against the upper punch. This provides the pressure required for cold forging and directly shapes the lower end face of the blank, ensuring the lower end face... In terms of matching with the bottom structure (frustum conical), the fourth lower die core is located on the side of the lower die shell near the upper die. The shape of the bottom of its cavity sidewall corresponds to the frustum conical (the basic structure inherited from the third cold-forged part), which limits the lower part of the blank and ensures the stability of the bottom structure. The shape of the upper part of the sidewall where it connects with the upper die corresponds to the sixth frustum conical, which constrains the deformation of the lower part of the blank (the "fourth frustum conical" of the original third cold-forged part), so that its cold-forged diameter is expanded to the sixth frustum conical (the diameter is larger than the original fourth frustum conical). At the same time, the shape of the cavity controls its taper and its connection relationship with the upper fifth frustum conical (the large bottom surface of the fifth frustum conical connects with the large bottom surface of the sixth frustum conical).

[0010] Furthermore, in this application, a cold heading die assembly for a seat rotating pin includes a fifth cold heading die comprising a fifth upper die and a fifth lower die. The fifth upper die is disposed above the fifth lower die. The fifth upper die includes a fifth upper die shell, and a fifth upper die core is embedded in the fifth upper die shell near the fifth lower die. The fifth upper die core has three arc-shaped protrusions for cold heading three arc grooves on the upper surface of the end cylindrical platform. The fifth lower die includes a fifth lower die shell, and a fifth lower punch passes through the fifth lower die shell, with the fifth lower punch facing the fifth upper die. The fifth lower punch is configured such that its shape near the fifth upper die corresponds to the lower end face of the finished product. A fifth lower die core is located on the side of the fifth lower die shell near the fifth upper die, and the fifth lower punch passes through it. The fifth lower die core has a fifth die core cavity, the bottom sidewall of which corresponds to the chamfered portion, and the upper radial sidewall of which corresponds to the end frustum. The upper axial sidewall of the fifth die core cavity has two recesses that descend axially, corresponding to the first and second protrusions respectively. The fifth upper die core is embedded in the fifth upper die shell near the lower die and has three arc-shaped protrusions that precisely match the three equally spaced arc grooves on the upper surface of the end frustum of the finished product. During cold heading, the arc-shaped protrusion directly acts on the corresponding area at the end of the fourth cold-headed part. The material is squeezed by pressure to form three equally divided arc grooves, ensuring that the position (equal division along the outer edge), curvature, depth and other detailed parameters of the arc grooves meet the design requirements, thus completing the forming of the key end features. The shape of the upper radial sidewall corresponds to the end frustum, constraining the radial deformation of the blank end. The first protrusion, fifth frustum and sixth frustum of the fourth cold-headed part are integrated and cold-headed into a regular end frustum, ensuring the overall dimensions of the frustum such as diameter and height. The upper axial sidewall has two recesses along the axial direction downward, corresponding to the first and second protrusions of the finished product, respectively. During cold heading, the material deformation is accommodated by the space of the recesses, so that two pre-defined protrusions are formed on the upper surface of the end frustum, ensuring the contour and positional accuracy of the protrusions. The shape of the bottom sidewall corresponds to the chamfer, constraining the deformation of the lower end of the blank (the end of the small bottom surface of the original frustum), cold-heading it into a smooth chamfer, eliminating sharp edges, and meeting the assembly safety requirements.

[0011] As can be seen from the above technical solution, this utility model has the following beneficial effects: 1. The cold heading mold assembly for seat rotating pins described in this utility model uses a multi-station, staged cold heading process combined with precise blank cutting of a material cutting component. This breaks down the complex irregular structure of the rotating pin into a series of localized forming processes. This avoids dimensional deviations caused by excessive deformation in a single processing step. Furthermore, by precisely matching each mold core, mold cavity, and forming feature, the dimensional tolerances of each structure are strictly controlled, ultimately achieving high-precision forming of complex geometric features while ensuring product consistency during mass production. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the forming process of each stage of a cold heading die assembly for a seat rotating pin according to the present invention. Figure 2 This is a cross-sectional view of a cold heading die assembly for a seat rotating pin according to the present invention. Figure 3 This is a cross-sectional view of the first cold heading die in a cold heading die assembly for a seat rotating pin according to the present invention. Figure 4 This is a cross-sectional view of the second cold heading die in a cold heading die assembly for a seat rotating pin according to this utility model; Figure 5 This is a cross-sectional view of the third cold heading die in a cold heading die assembly for a seat rotating pin according to this utility model; Figure 6 This is a cross-sectional view of the fourth cold heading die in a cold heading die assembly for a seat rotating pin according to this utility model; Figure 7 This is a cross-sectional view of the fifth cold heading die in a cold heading die assembly for a seat rotating pin according to this utility model; Figure 8 This is a schematic diagram of the process flow for a cold heading mold assembly for a seat rotating pin according to the present invention.

[0013] Explanation of reference numerals in the instruction manual: 1-First cold heading die, 11-First upper die, 111-First upper die shell, 112-First upper punch, 113-First upper die core, 1130-First upper die core cavity, 12-First lower die, 121-First lower die shell, 122-First lower punch, 123-First lower die core, 1230-First lower die core cavity; 2-Second cold heading die, 21-Second upper die, 211-Second upper die shell, 212-Second upper punch, 22-Second lower die, 221-Second lower die shell, 222-Second lower punch, 223-Second lower die core A, 2230-Second lower die core A cavity, 224-Second lower die core B, 2240-Second lower die core B cavity; 3-Third cold heading die, 31-Third upper die, 311-Third upper die shell, 312-Third upper punch, 313-Third upper die core, 3130-Third upper die cavity, 32-Third lower die, 321-Third lower die shell, 322-Third lower punch, 323-Third lower die core, 3230-Third lower die core cavity; 4-Fourth cold heading die, 41-Fourth upper die, 411-Fourth upper die shell, 412-Fourth upper punch, 413-Fourth upper die core, 4130-Fourth upper die cavity, 42-Fourth lower die, 421-Fourth lower die shell, 422-Fourth lower punch, 423-Fourth lower die core, 4230-Fourth die core cavity; 5-Fifth cold heading die, 51-Fifth upper die, 511-Fifth upper die shell, 512-Fifth upper die core, 52-Fifth lower die, 521-Fifth lower die shell, 522-Fifth lower punch, 523-Fifth lower die core, 5230-Fifth die core cavity; 6-Material cutting assembly, 61-Material cutting seat, 610-Material cutting cavity, 62-Material cutting section; 7-Cylindrical blank, 710-First cold-forged part, 711-First conical surface, 712-Second conical surface, 713-Third conical surface, 720-Second cold-forged part, 721-First frustum, 722-Frustum, 730-Third cold-forged part, 731-Cylindrical end, 732-Second frustum, 733-Third frustum, 734-Fourth frustum, 740-Fourth cold-forged part, 741-First protrusion, 742-Fifth frustum, 743-Sixth frustum, 750-Finished product, 751-End frustum, 7511-Arc groove, 7512-First protrusion, 7513-Second protrusion, 752-Chamfer. Detailed Implementation

[0014] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0015] Example 1 like Figure 1-8 As shown, this embodiment takes the mass production of automotive seat pivot pins as an example. The specific processing flow and the assembly method of each component are as follows: 1. Cutting process: Obtaining standard cylindrical blanks First, the cutting assembly 6 is activated, feeding the metal bar to be processed into the cutting cavity 610 of the cutting seat 61. The cutting cavity 610 radially limits the bar, ensuring that the bar's axis coincides with the reference axis of the subsequent cold heading process. Then, the cutting part 62 is controlled to cut the bar along the preset cutting position, obtaining a cylindrical blank 7 of uniform length. The dimensions of the cylindrical blank 7 perfectly match the blank specifications required for the subsequent cold heading process, laying the foundation for high-precision forming.

[0016] 2. First cold heading process: The cylindrical blank 7 is transferred to the processing station of the first cold heading die 1. The first cold heading die 1 consists of a first upper die 11 and a first lower die 12. The first upper die 11 is located on the upper end of the first lower die 12, and the two are coaxially arranged. The first upper mold 11 has a first upper punch 112 inserted inside the first upper mold shell 111. The first upper mold core 113, which is embedded in the first upper mold shell 111 near the first lower mold 12, is fitted outside the first upper punch 112, and the first upper mold core 113 has a first upper mold core cavity 1130. The first lower mold 12 has a first lower punch 122 inserted inside the first lower mold shell 121. The first lower punch 122 is directly opposite the first upper punch 112. The first lower mold shell 121 has a first lower mold core 123 on the side of the first lower mold shell 121 near the first upper mold 11. The first lower punch 122 is inserted into the first lower mold core 123, and the first lower mold core 123 has a first lower mold core cavity 1230.

[0017] The first cold heading die 1 is activated, the first upper punch 112 moves downward and the first lower punch 122 moves upward, applying cold heading pressure to the cylindrical blank 7. Under the constraint of the upper side wall of the first upper die cavity 1130, a first conical surface 711 is formed at the upper end of the cylindrical blank 7, and the first conical surface 711 and the side of the cylinder are smoothly transitioned through a chamfer structure; under the constraint of the bottom side wall of the first lower die cavity 1230, a second conical surface 712 and a third conical surface 713 are formed at the lower end of the cylindrical blank 7, which are coaxially connected in sequence, and the second conical surface 712 and the third conical surface 713 are smoothly transitioned through a conical surface, thus obtaining the first cold-headed part 710.

[0018] 3. Second cold heading process: The first cold-forged part 710 is transferred to the processing station of the second cold-forged die 2. The second cold-forged die 2 includes a second upper die 21 and a second lower die 22. The second upper die 21 is located on the upper end of the second lower die 22. A second upper punch 212 is inserted into the second upper die shell 211 of the second upper die 21. The shape of the end of the second upper punch 212 near the second lower die 22 matches the upper end face of the second cold-forged part 720 to be formed. A second lower punch 222 is inserted into the second lower die shell 221 of the second lower die 22. The second lower punch 222 is directly opposite the second upper punch 212, and the shape of the end of the second lower punch 222 near the second upper die 21 matches the lower end face of the second cold-forged part 720. The second lower mold shell 221 has a second lower mold core A223 on the side near the second upper mold 21. The second lower mold core A223 has a second lower mold core A cavity 2230. The second lower mold core B224 is located below the second lower mold core A223. The second lower mold core B224 has a second lower mold core B cavity 2240.

[0019] The second cold heading die 2 is activated, and the second upper punch 212 and the second lower punch 212 move towards each other to apply pressure. The first conical surface 711 of the first cold heading part 710 is cold heading into a first frustum 721 under the constraint of the middle side wall of the cavity 2230 of the second lower die core A; the second conical surface 712 and the third conical surface 713 of the first cold heading part 710 are integrated and cold heading into a single frustum 722 under the constraint of the bottom side wall of the cavity 2240 of the second lower die core B, finally obtaining the second cold heading part 720.

[0020] 4. Third cold heading process: The second cold-forged part 720 is transferred to the processing station of the third cold-forging die 3. The third cold-forging die 3 consists of a third upper die 31 and a third lower die 32. The third upper die 31 is located on the upper end of the third lower die 32. The third upper die 31 has a third upper die shell 311 inside which a third upper punch 312 is inserted. The shape of the end of the third upper punch 312 near the third lower die 32 matches the upper end face of the third cold-forged part 730. The third upper die shell 311 has a third upper die core 313 embedded on the side near the third lower die 32. The third upper die core 313 is fitted onto the third upper punch 312. The shape of the end of the third upper die core 313 near the third upper punch 312 matches the cylindrical end 731 to be formed. The third upper die core 313 has a third upper die cavity 3130. The shape of the middle part of the side wall of the third upper die cavity 3130 matches the second truncated cone 732. The shape of the lower part of the side wall where it connects with the third lower die 32 matches the third truncated cone 733.

[0021] The third lower die 32 has a third lower punch 322 inside the third lower die shell 321. The third lower punch 322 is directly opposite the third upper punch 312, and the shape of the end of the third lower punch 322 near the third upper die 31 matches the lower end face of the third cold-forged part 730. The third lower die shell 321 has a third lower die core 323 on the side near the third upper die 31. The third lower punch 322 passes through the third lower die core 323. The third lower die core 323 has a third lower die core cavity 3230. The shape of the upper part of the side wall of the third lower die core cavity 3230 where it connects with the upper die matches the fourth truncated cone 734, and the shape of the bottom of the side wall matches the truncated cone 722.

[0022] The third cold heading die 3 is activated, and the third upper punch 312 and the third lower punch 322 apply pressure to each other. Under the constraint of the third upper mold core 313 and the third upper mold cavity 3130, the first truncated cone 721 of the second cold-forged part 720 is gradually formed into a cylindrical end 731, a second truncated cone 732, and a third truncated cone 733 arranged sequentially from top to bottom. The lower end face of the cylindrical end 731 is connected to the small bottom face of the second truncated cone 732, and the large bottom face of the second truncated cone 732 is connected to the small bottom face of the third truncated cone 733. At the same time, under the constraint of the third lower mold core cavity 3230, the area above the truncated cone 722 of the second cold-forged part 720 is formed into a fourth truncated cone 734. The large bottom face of the third truncated cone 733 is connected to the large bottom face of the fourth truncated cone 734, and the small bottom face of the fourth truncated cone 734 is connected to the middle cylinder of the third cold-forged part 730, thus obtaining the third cold-forged part 730.

[0023] 5. Fourth cold heading process: The third cold-forged part 730 is transferred to the processing station of the fourth cold-forging die 4. The fourth cold-forging die 4 includes a fourth upper die 41 and a fourth lower die 42, with the fourth upper die 41 located on top of the fourth lower die 42. The fourth upper die 41 has a fourth upper die shell 411 inside which a fourth upper punch 412 is inserted. The shape of the end of the fourth upper punch 412 near the fourth lower die 42 matches the upper end face of the fourth cold-forged part 740. The fourth upper die shell 411 has a fourth upper die core 413 embedded on the side near the fourth lower die 42. The fourth upper die core 413 is fitted onto the fourth upper punch 412. The fourth upper die core 413 has a fourth upper die cavity 4130. The shape of the side wall of the fourth upper die cavity 4130 matches the first protrusion 741. The shape of the lower part of the side wall where it connects with the fourth lower die 42 matches the corresponding area of ​​the fourth cold-forged part 740.

[0024] The fourth lower die 42 has a fourth lower punch 422 inside the fourth lower die shell 421. The fourth lower punch 422 is directly opposite the fourth upper punch 412, and the shape of the end of the fourth lower punch 422 near the fourth upper die 41 matches the lower end face of the fourth cold-forged part 740. The fourth lower die shell 421 has a fourth lower die core 423 on the side near the fourth lower die 42. The fourth lower punch 422 passes through the fourth lower die core 423. The fourth lower die core 423 has a fourth die core cavity 4230. The bottom shape of the side wall of the fourth die core cavity 4230 matches the truncated cone 722, and the shape of the upper part of the side wall where it connects with the fourth upper die 41 matches the sixth truncated cone 743.

[0025] The fourth cold heading die 4 is activated, and the fourth upper punch 412 and the fourth lower punch 422 apply pressure to each other. Under the constraint of the fourth upper mold cavity 4130, the cylindrical end 731 and the second truncated cone 732 of the third cold-forged part 730 are integrated into the first protrusion 741 by cold forging; the third truncated cone 733 of the third cold-forged part 730 is expanded by cold forging into the fifth truncated cone 742, and the diameter of the large bottom surface of the fifth truncated cone 742 is larger than the diameter of the large bottom surface of the third truncated cone 733; the fourth truncated cone 734 of the third cold-forged part 730 is expanded by cold forging into the sixth truncated cone 743, the diameter of the large bottom surface of the sixth truncated cone 743 is larger than the diameter of the large bottom surface of the fourth truncated cone 734, and the large bottom surface of the fifth truncated cone 742 is connected to the large bottom surface of the sixth truncated cone 743, and the small bottom surface of the sixth truncated cone 743 is connected to the middle cylinder of the fourth cold-forged part 740, thus obtaining the fourth cold-forged part 740.

[0026] 6. Fifth cold heading process: The fourth cold-forged part 740 is transferred to the processing station of the fifth cold-forged die 5. The fifth cold-forged die 5 consists of a fifth upper die 51 and a fifth lower die 52, with the fifth upper die 51 located on top of the fifth lower die 52. The fifth upper mold shell 511 of the fifth upper mold 51 has a fifth upper mold core 512 embedded on the side near the fifth lower mold 52. The fifth upper mold core 512 has three arc-shaped protrusions for forming the arc groove 7511. The fifth lower mold shell 521 of the fifth lower mold 52 has a fifth lower punch 522 inserted inside. The fifth lower punch 522 is directly opposite the fifth upper mold core 512, and the shape of the end of the fifth lower punch 522 near the fifth upper mold 51 matches the lower end face of the finished product 750. The fifth lower mold shell 521 has a fifth lower mold core 523 on the side near the fifth upper mold 51. The fifth lower punch 522 is inserted into the fifth lower mold core 523. The fifth lower mold core 523 has a fifth mold core cavity 5230. The bottom sidewall shape of the fifth mold core cavity 5230 matches the chamfered part 752, and the upper radial sidewall matches the end frustum 751. The upper axial sidewall is provided with two recesses along the axial direction downward, which are respectively matched with the first protrusion 7512 and the second protrusion 7513.

[0027] Start the fifth cold heading die 5, and the fifth upper die core 512 and the fifth lower punch 522 apply pressure to each other. The first protrusion 741, the fifth truncated cone 742, and the sixth truncated cone 743 of the fourth cold-forged part 740 are integrated and cold-forged into an end truncated cone 751 under the constraint of the upper radial sidewall of the fifth mold cavity 5230. At the same time, the three arc-shaped protrusions of the fifth upper mold 512 are cold-forged into three equally spaced arc grooves 7511 on the upper surface of the end truncated cone 751. The two recesses on the upper axial sidewall of the fifth mold cavity 5230 are formed into the first protrusion 7512 and the second protrusion 7513 on the upper surface of the end truncated cone 751. In addition, the small bottom end of the truncated cone 722 of the fourth cold-forged part 740 is cold-forged into a chamfered part 752 under the constraint of the bottom sidewall of the fifth mold cavity 5230, finally obtaining the finished seat rotating pin 750.

[0028] This embodiment achieves high-precision forming of the complex structure of the seat rotating pin through the above six processes, utilizing the synergistic effect of the material cutting component 6 and five sets of cold heading dies, without any secondary processing, effectively ensuring product consistency and mechanical performance during mass production.

[0029] The above embodiments are exemplary and are intended to illustrate the technical concept and features of this utility model, so that those skilled in the art can understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the scope of protection of this utility model.

Claims

1. A cold heading die assembly for a seat rotating pin, characterized in that: include: The first cold heading die (1) is used to cold head the cylindrical blank (7) into the first cold heading part (710). At the first end of the first cold-forged part (710) along the axial direction, a first conical surface (711) is formed by cold forging with a first cold forging die (1), and the first conical surface (711) and the cylindrical side are transitioned by a chamfer structure; At the other end of the first cold-forged part (710) along the axial direction, a second conical surface (712) and a third conical surface (713) are formed by cold forging with the first cold forging die (1) and are connected coaxially in sequence. The second conical surface (712) and the third conical surface (713) are smoothly transitioned through the conical surface. The second cold heading die (2) is used to cold heading the first cold heading part (710) into the second cold heading part (720). The second cold heading die (2) cold heading the first conical surface (711) into the first frustum (721), and cold heading the second conical surface (712) and the third conical surface (713) into the frustum (722). The third cold heading die (3) is used to cold heading the second cold heading part (720) into the third cold heading part (730). The third cold heading die (3) cold-heads the first frustum (721) into a cylindrical end (731), a second frustum (732), a third frustum (733), and a fourth frustum (734). The cylindrical end (731), the second frustum (732), the third frustum (733), and the fourth frustum (734) are arranged sequentially from top to bottom. The lower end face of the cylindrical end (731) is connected to the small bottom face of the second frustum (732). The large bottom face of the second frustum (732) is connected to the small bottom face of the third frustum (733). The large bottom face of the third frustum (733) is connected to the large bottom face of the fourth frustum (734). The small bottom face of the fourth frustum (734) is connected to the central cylinder of the third cold-headed part (730). The fourth cold heading die (4) is used to cold heading the third cold heading part (730) into the fourth cold heading part (740). The fourth cold heading die (4) cold heading the cylindrical end (731) and the second truncated cone (732) into the first protrusion (741), and cold heading the third truncated cone (733) into the fifth truncated cone (742). The diameter of the large base of the fifth truncated cone (742) is larger than that of the third truncated cone (733). The large bottom diameter of the fifth truncated cone (733) is used to cold-forge the fourth truncated cone (734) into the sixth truncated cone (743). The large bottom surface of the fifth truncated cone (742) is connected to the large bottom surface of the sixth truncated cone (743). The large bottom diameter of the sixth truncated cone (743) is larger than the large bottom diameter of the fourth truncated cone (734). The small bottom surface of the sixth truncated cone (743) is connected to the central cylinder of the fourth cold-forged part (740). The fifth cold heading die (5) is used to cold heading the fourth cold heading part (740) into a finished product (750). The fifth cold heading die (5) cold heading the first protrusion (741), the fifth truncated cone (742), and the sixth truncated cone (743) into an end truncated cone (751), wherein the upper surface of the end truncated cone (751) is cold heading into three arc grooves (7511) along the outer edge, the upper surface of the end truncated cone (751) is cold heading into a first protrusion (7512) and a second protrusion (7513), and the small bottom end of the truncated cone (722) is cold heading into a chamfered part (752).

2. The cold heading die assembly for a seat rotating pin according to claim 1, characterized in that, It also includes: a cutting assembly (6), which includes: a cutting seat (61) with an upper opening and a cutting part (62). The cutting seat (61) is provided with a cutting cavity (610) for accommodating the bar, and the cutting part (62) is used to cut the bar in the cutting cavity (610) into cylindrical blanks (7).

3. A cold heading die assembly for a seat rotating pin according to claim 2, characterized in that, The first cold heading die (1) includes a first upper die (11) and a first lower die (12). The first upper die (11) is located on the upper end of the first lower die (12). The first upper die (11) includes a first upper die shell (111). A first upper punch (112) is provided on the first upper die shell (111). The shape of the end of the first upper punch (112) near the first lower die (12) corresponds to the upper end face of the first cold heading part (710). A first upper die core (113) is embedded on the side of the first upper die shell (111) near the first lower die (12). The first upper die core (113) is sleeved on the first upper punch (112). A first upper die core cavity (1130) is provided on the first upper die core (113). The shape of the upper part of the side wall of the first upper die core cavity (1130) corresponds to the first conical surface (711). The first lower die (12) includes a first lower die shell (121), on which a first lower punch (122) is provided. The first lower punch (122) is positioned directly opposite the first upper punch (112). The shape of the end of the first lower punch (122) near the first upper die (11) corresponds to the lower end face of the first cold-forged part (710). A first lower die core (123) is provided on the side of the first lower die shell (121) near the first upper die (11). The first lower punch (122) passes through the first lower die core (123). A first lower die core cavity (1230) is provided on the first lower die core (123). The shape of the bottom side wall of the first lower die core cavity (1230) corresponds to the second conical surface (712) and the third conical surface (713).

4. A cold heading die assembly for a seat rotating pin according to claim 3, characterized in that, The second cold heading die (2) includes a second upper die (21) and a second lower die (22). The second upper die (21) is located on the upper end of the second lower die (22). The second upper die (21) includes a second upper die shell (211). A second upper punch (212) is provided on the second upper die shell (211). The shape of the end of the second upper punch (212) near the second lower die (22) corresponds to the upper end face of the second cold heading part (720). The second lower die (22) includes a second lower die shell (221), on which a second lower punch (222) is provided. The second lower punch (222) is positioned directly opposite the second upper punch (212). The shape of the end of the second lower punch (222) near the second upper die (21) corresponds to the lower end face of the second cold-forged part (720). A second lower die core A (223) is provided on the side of the second lower die shell (221) near the second upper die (21). The second lower die core A (223) is provided with... There is a second lower die cavity A (2230), and the second cold-forged part (720) passes through the second lower die cavity A (2230). The shape of the middle side wall of the second lower die cavity A (2230) corresponds to the side ring surface of the first truncated cone (721). A second lower die cavity B (224) is provided below the second lower die cavity A (223), and a second lower die cavity B (2240) is provided on the second lower die cavity B (224). The bottom shape of the side wall of the second lower die cavity B (2240) corresponds to the truncated cone (722).

5. A cold heading die assembly for a seat rotating pin according to claim 4, characterized in that, The third cold heading die (3) includes a third upper die (31) and a third lower die (32). The third upper die (31) is located above the third lower die (32). The third upper die (31) includes a third upper die shell (311). A third upper punch (312) is inserted through the third upper die shell (311). The shape of the end of the third upper punch (312) near the third lower die corresponds to the upper end face of the third cold heading part (730). A third upper die core (313) is embedded on the side of the third upper die shell (311) near the third lower die (32). The third upper die core (313) is fitted onto the third upper punch (312). The shape of the end of the third upper die core (313) near the third upper punch (312) corresponds to the cylindrical end (731). The third upper mold core (313) is provided with a third upper mold cavity (3130). The shape of the middle part of the side wall of the third upper mold cavity (3130) corresponds to the shape of the second truncated cone (732). The shape of the lower part of the side wall of the third upper mold cavity (3130) where it connects with the third lower mold (32) corresponds to the shape of the third truncated cone (733). The third lower die (32) includes a third lower die shell (321), on which a third lower punch (322) is provided. The third lower punch (322) is positioned opposite the third upper punch (312). The shape of the end of the third lower punch (322) near the third upper die (31) corresponds to the lower end face of the third cold-forged part (730). A third lower die core (323) is provided on the side of the third lower die shell (321) near the third upper die (31). The third lower punch (322) is provided on the third lower die core (323). A third lower die core cavity (3230) is provided on the third lower die core (323). The shape of the upper part of the side wall of the third lower die core cavity (3230) where it connects with the upper die corresponds to the fourth truncated cone (734). The shape of the bottom of the side wall of the third lower die core cavity (3230) corresponds to the truncated cone (722).

6. A cold heading die assembly for a seat rotating pin according to claim 5, characterized in that, The fourth cold heading die (4) includes a fourth upper die (41) and a fourth lower die (42). The fourth upper die (41) is located above the fourth lower die (42). The fourth upper die (41) includes a fourth upper die shell (411). A fourth upper punch (412) is provided on the fourth upper die shell (411). The shape of the end of the fourth upper punch (412) near the fourth lower die corresponds to the upper end face of the fourth cold heading part (740). The fourth upper die shell (411) A fourth upper die core (413) is embedded near the side of the fourth lower die (42). The fourth upper die core (413) is sleeved on the fourth upper punch (412). The fourth upper die core (413) is provided with a fourth upper die cavity (4130). The side wall shape of the fourth upper die cavity (4130) corresponds to the first protrusion (741). The shape of the lower part of the side wall of the fourth upper die cavity (4130) where it connects with the fourth lower die (42) corresponds to the fourth cold-forged part (740). The fourth lower die (42) includes a fourth lower die shell (421), on which a fourth lower punch (422) is mounted. The fourth lower punch (422) is positioned directly opposite the fourth upper punch (412). The shape of the end of the fourth lower punch (422) near the fourth upper die (41) corresponds to the lower end face of the fourth cold-forged part (740). The side of the fourth lower die shell (421) near the fourth lower die (42) A fourth lower die core (423) is provided, and a fourth lower punch (422) is provided on the fourth lower die core (423). A fourth die core cavity (4230) is provided on the fourth lower die core (423). The bottom shape of the side wall of the fourth die core cavity (4230) corresponds to the truncated cone (722), and the shape of the upper part of the side wall of the fourth die core cavity (4230) where it connects with the fourth upper die (41) corresponds to the sixth truncated cone (743).

7. A cold heading die assembly for a seat rotating pin according to claim 5, characterized in that, The fifth cold heading die (5) includes a fifth upper die (51) and a fifth lower die (52). The fifth upper die (51) is located on the upper end of the fifth lower die (52). The fifth upper die (51) includes a fifth upper die shell (511). The fifth upper die shell (511) has a fifth upper die core (512) embedded on the side near the fifth lower die (52). The fifth upper die core (512) has three arc-shaped protrusions for cold heading three arc grooves (7511) on the upper surface of the end frustum (751). The fifth lower die (52) includes a fifth lower die shell (521), on which a fifth lower punch (522) is provided. The fifth lower punch (522) is positioned directly opposite the fifth upper die core (512). The shape of the end of the fifth lower punch (522) near the fifth upper die (51) corresponds to the lower end face of the finished product (750). The fifth lower die shell (521) is provided with a fifth lower die core (523) on the side near the fifth upper die (51). It is installed on the fifth lower mold core (523), and the fifth lower mold core (523) is provided with a fifth mold core cavity (5230). The bottom side wall shape of the fifth mold core cavity (5230) corresponds to the chamfered part (752). The upper radial side wall of the fifth mold core cavity (5230) corresponds to the end frustum (751). The upper axial side wall of the fifth mold core cavity (5230) is provided with two recesses along the axial direction downward, which correspond to the first protrusion (7512) and the second protrusion (7513) respectively.

Images