Flange shaft cold upsetting forming die and cold upsetting die set

Abstract

The application provides a flange shaft cold upsetting forming die and a cold upsetting die set, which comprises a main die and a punch die arranged oppositely. The main die comprises a main die sleeve, a first forming die assembly, a second forming die assembly and a spring seat arranged in sequence in the main die sleeve, and the first forming die assembly and the second forming die assembly form a die cavity. A first elastic element is arranged between the first forming die assembly and the second forming die assembly. The spring seat is arranged at an end of the second forming die assembly away from the first forming die assembly, and a second elastic element is arranged in the spring seat. The second elastic element keeps an axial gap between the second forming die assembly and the spring seat in a natural state. A ejection mechanism is arranged at an end of the main die away from the punch die, and a ejector pin of the ejection mechanism extends into the die cavity. The first elastic element and the second elastic element are arranged to realize delayed forming, avoid folding defects caused by metal flow and improve the forming quality of the expansion part.

Description

Technical Field

[0001] This invention belongs to the field of cold heading mold technology, specifically relating to a flange shaft cold heading forming mold and a cold heading mold assembly. Background Technology

[0002] Flange shafts are common mechanical transmission components, widely used in automobiles, construction machinery, and other fields. The flange shaft involved in this invention has a special structure: a flange is located in the middle, and a thicker expansion portion is located at one end, with transition steps formed at both ends of the expansion portion. This structure is used for mounting bearings, seals, or as a positioning stop.

[0003] Cold heading is a highly efficient metal forming method. Existing cold heading dies typically employ an integral master die structure, meaning a cavity with the same shape as the finished product is machined inside a single die core. During cold heading, the die presses the blank into the die cavity, forcing the metal to flow simultaneously towards the flange, the expansion section, and multiple steps. Because the steps at both ends of the expansion section are relatively close together, folds or cracks can easily occur at the step transitions when the metal is filled simultaneously. The expansion section has a large volume, requiring a large upsetting force, while the step areas require precise control of the metal flow rate, making it difficult to balance both aspects simultaneously.

[0004] Therefore, there is an urgent need for a flange cold heading die and cold heading die set that can improve metal flow and increase forming accuracy. Summary of the Invention

[0005] Purpose of the invention: In order to overcome the above shortcomings, the present invention provides a flange cold heading forming die and a cold heading die assembly, which can realize the step-by-step sequential forming of flanges, improve metal flow, and increase forming accuracy and die life.

[0006] Technical Solution: To achieve the above objectives, this invention provides a flange cold heading forming die, comprising a main die and a punch die arranged opposite to each other. The main die includes a main die sleeve, within which a first forming die assembly, a second forming die assembly, and a spring seat are sequentially arranged. The first forming die assembly and the second forming die assembly close together to form a die cavity. A first elastic element is provided between the first forming die assembly and the second forming die assembly, applying an elastic force to the first forming die assembly and the second forming die assembly to separate them, thereby maintaining an axial clearance in their natural state. The spring seat is located at the end of the second forming die assembly away from the first forming die assembly, and a second elastic element is provided within the spring seat. The second elastic element maintains an axial clearance between the second forming die assembly and the spring seat in their natural state. An ejector mechanism is provided at the end of the main die away from the punch die, and an ejector pin of the ejector mechanism extends into the die cavity.

[0007] This invention achieves delayed forming by incorporating a first elastic element and a second elastic element. The forming process includes: a first stage, where the die presses down to compress the first elastic element, and the first forming die assembly and the second forming die assembly close together to form a closed mold cavity; a second stage, where the die presses down further to compress the second elastic element, the second forming die assembly moves downward as a whole, the blank is axially compressed by the ejector pin, and the material begins to flow radially, initially filling the expansion portion; a third stage, the punch compresses the material from top to bottom, creating compression that forces the material to fill the mold cavity, thus fully forming the expansion portion. This step-by-step forming method avoids folding defects caused by metal flow and improves the forming quality of the expansion portion.

[0008] Furthermore, in the aforementioned flange cold heading die, the elastic force of the second elastic element is greater than that of the first elastic element.

[0009] Furthermore, in the aforementioned flange cold heading die, the first forming die assembly includes an upper die core composed of multiple die segments, and a first movable sleeve fitted around the outer side of the upper die core. The outer periphery of the upper die core is inverted conical, and the inner hole of the first movable sleeve has a conical surface that mates with the outer periphery of the upper die core. The first movable sleeve can slide axially relative to the main die sleeve. Spring holes are provided on adjacent sides of the die segments of the upper die core, and springs are installed in the spring holes, so that when the upper die core moves axially relative to the first movable sleeve, the multiple die segments of the upper die core radially close or open. The top end of the first elastic element abuts against the bottom end of the upper die core.

[0010] Furthermore, in the aforementioned flange cold heading die, the second forming die assembly includes a second movable sleeve. The second movable sleeve has a through groove for placing the first elastic element and a groove for installing the lower die core, which is disposed opposite to the upper die core. A pad is provided on the side of the second movable sleeve away from the first forming die assembly, and the lower end of the first elastic element abuts against the top surface of the pad.

[0011] Furthermore, in the aforementioned flange cold heading die, a guide post is connected to the bottom surface of the pad block, and the second elastic element is sleeved on the outer periphery of the guide post. The guide post guides and prevents bending of the second elastic element, ensuring stable compression of the second elastic element.

[0012] Furthermore, in the aforementioned flange cold heading die, the spring seat is provided with a countersunk hole for accommodating the second elastic element. The top end of the second elastic element extends out of the countersunk hole and abuts against the bottom surface of the pad block. The countersunk hole is used to position and guide the second elastic element, preventing displacement and ensuring its stability.

[0013] Furthermore, in the aforementioned flange cold heading forming mold, the ejection mechanism includes an inner sliding sleeve fitted around the outer periphery of the ejector pin, and an outer sliding sleeve fitted around the outer periphery of the inner sliding sleeve. The top end of the outer sliding sleeve is connected to the main mold sleeve, the inner sliding sleeve and the outer sliding sleeve are slidably connected, and the ejector pin is slidably connected within a through cavity provided along the axis of the inner sliding sleeve. The inner sliding sleeve includes a sliding sleeve body and a limiting ring located at the bottom end of the sliding sleeve body. A spring is fitted around the outer periphery of the sliding sleeve body, with both ends of the spring abutting against the limiting ring and the bottom end of the outer sliding sleeve, respectively. The lower end of the ejector pin is opposite to the striker of the cold heading machine. During the forming process, the ejector pin is struck by the striker and moves upward, participating in the forming process. At the same time, the inner sliding sleeve can dynamically move with the ejector pin to meet the requirements of long-stroke ejection.

[0014] Furthermore, in the aforementioned flange cold heading die, the die includes a die sleeve, and the die sleeve has a first sliding cavity and a second sliding cavity along its axis. The first sliding cavity contains a die assembly, which includes a support sleeve and a die core disposed within the support sleeve. The second sliding cavity contains a punch assembly, which includes a punch sleeve, a punch, and a punch pad disposed within the punch sleeve, with the punch pad abutting against the top of the punch. The support sleeve and the die core have a through cavity for the punch to pass through, and the lower end of the punch is slidably disposed within the through cavity.

[0015] Furthermore, in the aforementioned flange cold heading die, the end of the die core facing the main die is provided with a cavity for accommodating the pre-headed hexagonal flange, and the cavity is connected to the through cavity. The cavity is used to pre-position the hexagonal flange of the workpiece, improving the forming accuracy.

[0016] A cold heading die assembly includes a first cold heading die, a second cold heading die, a third cold heading die, a fourth cold heading die, a fifth cold heading die, and a sixth cold heading die arranged sequentially. The sixth cold heading die is the aforementioned flange shaft cold heading forming die.

[0017] As can be seen from the above technical solution, the present invention has the following beneficial effects: ①The flange cold heading forming mold and cold heading mold assembly of the present invention avoid the folding defects of metal by step-by-step delayed forming, thereby improving the forming quality.

[0018] ② In the first forming die assembly, when the upper die core, composed of multiple die segments, moves relative to the first movable sleeve, under the pressure of the die, the upper die core moves downward relative to the first movable sleeve. The first movable sleeve forces the multiple die segments to radially close, forming a complete cavity. The conical fit ensures the radial position of the upper die core, improving the concentricity of the cavity and forming accuracy. When the die is opened, the first movable sleeve moves upward, and the small spring in the spring hole causes the die segments to open radially, facilitating the removal of the workpiece with the central expansion portion.

[0019] ③ The inner sliding sleeve can move dynamically with the ejector pin, so that the ejector pin is always supported, ensuring the stability of the ejector pin and meeting the requirements of long stroke ejection.

[0020] ④ The cold heading die set contains six stations, of which the sixth station uses the aforementioned die, enabling continuous cold heading at multiple stations with high production efficiency. Attached Figure Description

[0021] Figure 1 This is an axial sectional view of the flange cold heading die of the present invention; Figure 2 This is an axial sectional view of the main mold; Figure 3 This is an axial sectional view of the die; Figure 4 This is an axial sectional view of the cold heading die assembly of the present invention; Figure 5 This is a process diagram of the cold heading die assembly of the present invention.

[0022] In the diagram: 1. Main mold; 11. Main mold sleeve; 13. First forming mold assembly; 131. Upper mold core; 132. First movable sleeve; 14. Second forming mold assembly; 141. Second movable sleeve; 1411. Through groove; 1412. Groove; 142. Lower mold core; 143. Pad; 144. Guide post; 15. Spring seat; 152. Countersunk hole; 16. First elastic element; 151. Second elastic element; 2. Punch; 21. Punch sleeve; 211. First slide cavity; 212. Second slide cavity; 22. Support sleeve; 23. Punch core; 232. Through cavity; 2321. Cavity; 24. Punch sleeve; 25. Punch; 26. Punch pad; 3. 1. Ejection mechanism; 31. Ejector pin; 32. Inner sliding sleeve; 321. Sliding sleeve body; 322. Limiting ring; 33. Outer sliding sleeve; 100. First cold heading mold; 101. First pre-heading part; 102. Reduction end; 200. Second cold heading mold; 201. Second pre-heading part; 202. First pre-heading section; 300. Third cold heading mold; 301. Third pre-heading part; 302. Second pre-heading section; 400. Fourth cold heading mold; 401. Fourth pre-heading part; 402. Hexagonal section; 500. Fifth cold heading mold; 501. Fifth pre-heading part; 502. Hexagonal flange; 600. Sixth cold heading mold; 601. Finished flange shaft; 602. Expansion section. Detailed Implementation Example

[0023] like Figure 1The flange cold heading die shown includes a main die 1 and a punch 2 arranged opposite to each other. The main die 1 includes a main die sleeve 11, which is cylindrical. Inside the main die sleeve 11, a first forming die assembly 13, a second forming die assembly 14, and a spring seat 15 are arranged sequentially along the axis. The first forming die assembly 13 and the second forming die assembly 14 close together to form a die cavity. A first elastic element 16 is provided between the first forming die assembly 13 and the second forming die assembly 14, and the first elastic element 16 applies an elastic force to the first forming die assembly 13 and the second forming die assembly 14 to separate them. The spring seat 15 is located at the end of the second forming die assembly 14 away from the first forming die assembly 13, and a second elastic element 151 is provided inside the spring seat 15. The second elastic element 151 maintains an axial gap between the second forming die assembly 14 and the spring seat 15 in its natural state. An ejector mechanism 3 is provided at the end of the main die 1 away from the punch 2, and the ejector pin 31 of the ejector mechanism 3 extends into the die cavity.

[0024] This invention achieves delayed forming by incorporating a first elastic element and a second elastic element. The forming process includes: a first stage, where the die presses down to compress the first elastic element, and the first forming die assembly and the second forming die assembly close together to form a closed mold cavity; a second stage, where the die presses down further to compress the second elastic element, and the second forming die assembly retracts as a whole. Simultaneously, the movement of the die and the mold cavity causes axial compression of the blank, and the material begins to flow radially, initially filling the expansion portion; a third stage, where the punch continues to press down, squeezing the material from top to bottom, forcing the material to fill the mold cavity, and completely forming the expansion portion. This step-by-step forming method avoids folding defects caused by metal flowing in multiple directions simultaneously, improving the forming quality of the expansion portion.

[0025] In this embodiment, both the first elastic element 16 and the second elastic element 151 are compression springs, and the elastic force of the second elastic element 151 is greater than the elastic force of the first elastic element 16.

[0026] like Figure 2The flange cold heading die shown includes a first forming die assembly 13 comprising an upper die core 131 composed of multiple die segments, and a first movable sleeve 132 fitted around the outer side of the upper die core 131. Each of the multiple die segments of the upper die core 131 has a spring hole on an adjacent side, and a small spring is installed within each spring hole. The outer periphery of the upper die core 131 is inverted conical (i.e., the diameter is larger at the end near the die and smaller at the end near the ejection). The inner hole of the first movable sleeve 132 has a conical surface that mates with the outer periphery of the upper die core 131. When the upper die core 131 moves downward, the conical surface of the first movable sleeve 132 forces the multiple die segments of the upper die core 131 to radially close, forming a closed, complete cavity. When the upper die core 131 moves upward, the small springs within the spring holes force the multiple die segments of the upper die core 131 to radially open, facilitating the removal of the workpiece. The outer circle of the first movable sleeve 132 is clearance-fitted with the inner hole of the main die sleeve 11, allowing the first movable sleeve 132 to slide axially relative to the main die sleeve 11. The top of the first elastic element 16 abuts against the bottom of the upper mold core 131.

[0027] In this embodiment, the second forming die assembly 14 includes a second movable sleeve 141. The second movable sleeve 141 has a through groove 1411 near the die 2 for placing the first elastic element 16, and a groove 1412 for mounting the lower die core 142. The lower die core 142 is disposed opposite to the upper die core 131. A pad 143 is fixedly connected to the side of the second movable sleeve 141 away from the first forming die assembly 13, and the lower end of the first elastic element 16 abuts against the top surface of the pad 143. The die core 142 and the upper die core 131 are disposed opposite to each other, forming a die cavity for forming the flange shaft expansion portion 602.

[0028] In this embodiment, the bottom surface of the pad 143 is connected to the guide post 144, and the second elastic element 151 is sleeved on the outer periphery of the guide post 144.

[0029] In this embodiment, the spring seat 15 is provided with a countersunk hole 152 for accommodating the second elastic element 151, and the top end of the second elastic element 151 extends out of the countersunk hole 152 and abuts against the bottom surface of the pad block 143.

[0030] In this embodiment, the ejection mechanism 3 includes an inner sliding sleeve 32 sleeved around the outer periphery of the ejector pin 31, and an outer sliding sleeve 33 sleeved around the outer periphery of the inner sliding sleeve 32. The upper end of the outer sliding sleeve 33 is fixedly connected to the lower end of the main mold sleeve 11, the inner hole of the inner sliding sleeve 32 is slidably engaged with the outer sliding sleeve 33, and the ejector pin 31 is slidably connected to the through cavity provided along the axis of the inner sliding sleeve 32. The inner sliding sleeve 32 includes a sliding sleeve body 321 and a limiting ring 322 provided at the bottom end of the sliding sleeve body 321. A spring is sleeved around the outer periphery of the sliding sleeve body 321, the upper end of the spring abuts against the bottom end of the outer sliding sleeve 33, and the lower end of the spring abuts against the upper end face of the limiting ring 322. When not struck by the ejector pin, the ejector pin 31 is in its lowest position. The lower end of the ejector pin 31 is opposite to the ejector pin of the cold heading machine (not shown in the figure). After mold separation, the ejector pin strikes the ejector pin 31, ejecting the finished product. Meanwhile, the inner sliding sleeve 32 can move dynamically with the ejector pin 31. That is, when the ejector pin 31 moves upward, the inner sliding sleeve 32 slides upward synchronously within the outer sliding sleeve 33, and the spring is compressed. After the ejector pin retracts, the spring pushes the inner sliding sleeve 32 to reset downward, which meets the long stroke ejection requirement and ensures the guiding accuracy of the ejector pin.

[0031] like Figure 3 The flange cold heading die shown includes a die 2 comprising a die sleeve 21, with a first sliding cavity 211 and a second sliding cavity 212 along its axis. The first sliding cavity 211 contains a die assembly, which includes a support sleeve 22 and a die core 23 disposed within the support sleeve 22. The second sliding cavity 212 contains a punch assembly, which includes a punch sleeve 24, a punch 25, and a punch pad 26 disposed within the punch sleeve 24. The punch pad 26 abuts against the top of the punch 25. The support sleeve 22 and the die core 23 have a through cavity 232 through which the punch 25 passes, and the lower end of the punch 25 is slidably disposed within the through cavity 232.

[0032] In this embodiment, the die core 23 is provided with a cavity 2321 for accommodating the hexagonal flange of the pre-forged part at one end facing the main die 1, and the cavity 2321 is connected to the through cavity 232.

[0033] For ease of understanding, the following motion directions are defined: the direction in which the punch 2 moves towards the main die 1 is "downward" or "forward," and the opposite is "upward" or "reverse." The flange shaft to be formed has the following characteristics: a hexagonal flange 502 in the middle, and a relatively thick expansion part 602 at one end, with a first step and a second step respectively at both ends of the expansion part. The working process of this invention is as follows: First stage: The die 2 moves downwards, and the cavity 2321 of the die core 23 first contacts the fifth pre-forged part 501, wrapping and positioning the hexagonal flange 502 and pushing it downwards. The die 2 continues to press down, and the support sleeve 22 contacts the top surface of the upper die core 131 and begins to compress the upper die core 131. The upper die core 131 overcomes the elastic force of the first elastic element 16 and moves downwards, and the first movable sleeve 132 forces the upper die core 131 to radially close. When the die 2 presses down until the upper die core 131 and the lower die core 142 are completely fitted, the mold cavity closes, forming a closed cavity consistent with the shape of the flange shaft expansion part. During this process, because the elastic force of the second elastic element 151 is greater than that of the first elastic element 16, the second elastic element 151 has not yet been compressed, and the second forming die assembly 14 remains stationary.

[0034] Second stage: After the mold cavity is closed, the motion resistance inside the main mold 1 increases. The punch 2 continues to press down, and the pressure is transmitted to the pad block 143 through the already closed upper mold core 131 and lower mold core 142, thereby compressing the second elastic element 151.

[0035] At this time, the second molding die assembly 14 moves downward as a whole. The upper die core 131 and the first movable sleeve 132 are also forced to move downward synchronously. The fifth pre-forged part 501, which is enclosed in the mold cavity, is subjected to the squeezing force of the ejector pin 31, and the material is forced to flow laterally into the mold cavity, starting to fill the contour of the expansion part. The expansion part 602 is initially formed, but is not yet completely filled.

[0036] When the second elastic element 151 is compressed until the bottom surface of the pad 143 contacts the top surface of the spring seat 15, the punch 25 continues to move downward to press the top of the fifth pre-forged part 501, and the material flows further, filling all corners of the mold cavity, so that the expansion part 602 is fully formed.

[0037] Then, the main mold 1 separates from the punch 2, the punch 2 retracts upward, the first elastic element 16 and the second elastic element 151 reset successively, the first forming mold assembly 13 separates from the second forming mold assembly 14, and the multiple mold lobes of the upper mold core 131 open radially. The striker of the cold heading machine pushes the lower end of the ejector pin 31, the ejector pin 31 moves upward to push the formed flange shaft out of the mold cavity, the inner sliding sleeve 32 slides upward synchronously, and the spring is compressed. After ejection is completed, the striker retracts, the spring pushes the inner sliding sleeve 32 and the ejector pin 31 downward to reset, waiting for the next forming cycle.

[0038] like Figure 4-5 The cold heading die assembly shown includes a first cold heading die 100, a second cold heading die 200, a third cold heading die 300, a fourth cold heading die 400, a fifth cold heading die 500, and a sixth cold heading die 600 arranged sequentially. The sixth cold heading die 600 is the aforementioned flange shaft cold heading forming die.

[0039] The first cold heading die 100 is used to reduce the diameter of the lower end of the billet to form a reduced diameter end 102, forming a first pre-headed part 101; the second cold heading die 200 is used to perform upper diameter reduction pre-heading on the first pre-headed part 101 to form a second pre-headed part 201 having a first pre-headed portion 202; the third cold heading die 300 is used to reduce the diameter at both ends of the second pre-headed part 201 and shape the first pre-headed portion 202 to form a third pre-headed part 301 having a second pre-headed portion 302; The fourth cold heading die 400 is used to shape the second pre-heading portion 302 of the third pre-heading part 301 to form the fourth pre-heading part 401 with a hexagonal portion 402; the fifth cold heading die 500 is used to further shape the hexagonal portion 402 to form the fifth pre-heading part 501 with a hexagonal flange 502; the sixth cold heading die 600 is used to shape the lower end rod portion of the fifth pre-heading part 501 to obtain the flange shaft finished product 601 with an expansion portion 602.

[0040] In this embodiment, the workpieces are automatically transferred between the cold heading dies via a clamping mechanism. The clamping mechanism is driven by the feeding system of the cold heading machine and transfers the workpieces from the previous station to the next station according to a set sequence. The first cold heading die 100 to the fifth cold heading die 500 can adopt conventional cold heading die structures in the prior art, and their specific structures will not be described in detail here.

[0041] The above embodiments are exemplary and are intended to illustrate the technical concept and features of the present invention, so that those skilled in the art can understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A cold heading forming die for a flange shaft, characterized in that: The system includes a main mold (1) and a punch (2) arranged opposite to each other; the main mold (1) includes a main mold sleeve (11), and a first forming mold assembly (13), a second forming mold assembly (14) and a spring seat (15) are sequentially arranged inside the main mold sleeve (11). The first forming mold assembly (13) and the second forming mold assembly (14) close together to form a mold cavity; a first elastic element (16) is provided between the first forming mold assembly (13) and the second forming mold assembly (14), and the first elastic element (16) provides force to the first forming mold assembly (13) and the second forming mold assembly (14). The molding die assembly (14) is subjected to an elastic force that separates them from each other; the spring seat (15) is located at the end of the second molding die assembly (14) away from the first molding die assembly (13), and the spring seat (15) is provided with a second elastic element (151), which makes the second molding die assembly (14) and the spring seat (15) maintain an axial gap in their natural state; the main die (1) is provided with an ejector mechanism (3) at the end away from the punch (2), and the ejector pin (31) of the ejector mechanism (3) extends into the mold cavity.

2. The flange cold heading forming die according to claim 1, characterized in that: The elastic force of the second elastic element (151) is greater than that of the first elastic element (16).

3. The flange cold heading forming die according to claim 1, characterized in that: The first molding die assembly (13) includes an upper die core (131) composed of multiple die segments, and a first movable sleeve (132) sleeved on the outside of the upper die core (131); the outer periphery of the upper die core (131) is inverted conical, and the inner hole of the first movable sleeve (132) has a conical surface that matches the outer periphery of the upper die core (131); the first movable sleeve (132) can slide axially relative to the main die sleeve (11), and spring holes are provided on the adjacent sides of the die segments of the upper die core (131), and small springs are provided in the spring holes; the top end of the first elastic element (16) abuts against the bottom end of the upper die core (131).

4. The flange cold heading forming die according to claim 3, characterized in that: The second molding die assembly (14) includes a second movable sleeve (141), which has a through groove (1411) for placing the first elastic element (16) and a groove (1412) for installing the lower die core (142), which is disposed opposite to the upper die core (131); a pad (143) is provided on the side of the second movable sleeve (141) away from the first molding die assembly (13), and the lower end of the first elastic element (16) abuts against the top surface of the pad (143).

5. The flange cold heading forming die according to claim 4, characterized in that: The bottom surface of the pad (143) is connected to a guide post (144), and the second elastic element (151) is sleeved on the outer periphery of the guide post (144).

6. The flange cold heading forming die according to claim 4, characterized in that: The spring seat (15) is provided with a countersunk hole (152) for accommodating a second elastic element (151), the top of the second elastic element (151) extending out of the countersunk hole (152) and abutting against the bottom surface of the pad (143).

7. The flange cold heading forming die according to claim 1, characterized in that: The ejection mechanism (3) includes an inner sliding sleeve (32) sleeved on the outer periphery of the ejector pin (31) and an outer sliding sleeve (33) sleeved on the outer periphery of the inner sliding sleeve (32); the top end of the outer sliding sleeve (33) is connected to the main mold sleeve (11), the inner sliding sleeve (32) and the outer sliding sleeve (33) are slidably connected, and the ejector pin (31) is slidably connected in the through cavity provided along the axis of the inner sliding sleeve (32); the inner sliding sleeve (32) includes a sliding sleeve body (321) and a limiting ring (322) provided at the bottom end of the sliding sleeve body (321), and a spring is sleeved on the outer periphery of the sliding sleeve body (321), and the two ends of the spring abut against the limiting ring (322) and the bottom end of the outer sliding sleeve (33) respectively.

8. The flange cold heading forming die according to claim 1, characterized in that: The die (2) includes a die sleeve (21), and the die sleeve (21) is provided with a first sliding cavity (211) and a second sliding cavity (212) along the axis. The first sliding cavity (211) is provided with a die assembly, which includes a support sleeve (22) and a die core (23) provided in the support sleeve (22). The second sliding cavity (212) is provided with a punch assembly, which includes a punch sleeve (24), a punch (25) and a punch pad (26) provided in the punch sleeve (24), and the punch pad (26) abuts against the top of the punch (25). The support sleeve (22) and the die core (23) are provided with a through cavity (232) through which the punch (25) passes, and the lower end of the punch (25) is slidably provided in the through cavity (232).

9. The flange cold heading forming die according to claim 8, characterized in that: The die core (23) has a cavity (2321) at one end facing the main die (1) for accommodating the hexagonal flange of the pre-forged part, and the cavity (2321) is connected to the through cavity (232).

10. A cold heading die assembly, characterized in that: It includes a first cold heading mold (100), a second cold heading mold (200), a third cold heading mold (300), a fourth cold heading mold (400), a fifth cold heading mold (500), and a sixth cold heading mold (600) arranged in sequence; the sixth cold heading mold (600) is the flange shaft cold heading forming mold according to any one of claims 1-9.

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