A cold heading forming die for a core rod nail head

Abstract

The utility model provides a kind of core rod nail head cold heading forming die, it is related to metal processing technical field, the core rod nail head cold heading forming die includes outer sleeve, upper die core and lower die core, outer sleeve has the assembly cavity of axial through, upper die core and lower die core are embedded in assembly cavity and with outer sleeve interference fit, upper die core has the first cavity of axial through, lower die core has the second cavity of axial through, the inner diameter of second cavity is less than the inner diameter of first cavity, lower die core and upper die core abut, the inner edge of the end of lower die core is projected to the inner wall of upper die core and forms first limiting step. The core rod nail head cold heading forming die proposed in the utility model can effectively eliminate the surface defect at core rod nail head.

Description

Technical Field

[0001] This utility model relates to the field of metal processing technology, and in particular to a cold heading mold for core rod nail heads. Background Technology

[0002] Cold heading is a metal forming process that uses cold plastic deformation. It is mainly used to manufacture fasteners or other shaft parts with complex structures and high precision requirements. Compared to traditional machining methods such as turning and milling, which require multiple steps, cold heading can directly form complex structures by applying high pressure to wire through a die. Traditional cutting processes result in a material utilization rate of only 25% to 35%, while cold heading can achieve over 85%, significantly reducing raw material consumption.

[0003] Cold heading dies are core tools in metal plastic forming. They withstand ultra-high pressure at room temperature, extruding wire at high speed into fasteners or other parts through a precision cavity. Existing cold heading dies lack venting structures. During the metal extrusion process, some air cannot escape, resulting in insufficient filling of the precision cavity with metal material. Consequently, the surface of the cold-headed parts has defects and fails to meet process requirements. When cold heading blind rivets, the deformation at the rivet head is not uniform, and the material filling is insufficient, leading to the rivet head dimensions not meeting requirements.

[0004] In addition, the existing cold heading dies have a short lifespan. After a period of cold heading operation, the machine needs to be stopped to replace the cold heading dies, which not only seriously affects production efficiency but also increases the cost of die consumption, leading to an increase in the overall production cost of fasteners.

[0005] In view of this, based on years of experience in production and design in this and related fields, the inventor has designed a cold heading mold for core rod nail heads through repeated experiments in order to solve the problems existing in the prior art. Utility Model Content

[0006] The purpose of this utility model is to provide a cold heading mold for core rod nail heads, which can effectively eliminate surface defects at the core rod nail heads.

[0007] To achieve the above objectives, this utility model proposes a cold heading forming mold for core rod heads. The mold includes an outer sleeve, an upper mold core, and a lower mold core. The outer sleeve has an axially penetrating assembly cavity. The upper mold core and the lower mold core are both embedded in the assembly cavity and are interference-fitted with the outer sleeve. The upper mold core has an axially penetrating first cavity, and the lower mold core has an axially penetrating second cavity. The inner diameter of the second cavity is smaller than the inner diameter of the first cavity. The lower mold core abuts against the upper mold core, and the inner edge of the end of the lower mold core protrudes from the inner wall of the upper mold core, forming a first limiting step.

[0008] As described above, in the cold heading die for core rod heads, the outer sleeve has a first outer sleeve body and a second outer sleeve body. The first outer sleeve body has a first through cavity that extends axially. The first through cavity includes a first segment and a second segment. The inner diameter of the first segment is smaller than the inner diameter of the second segment and forms a second limiting step. The second outer sleeve body passes through the second segment and abuts against the second limiting step. The second outer sleeve body has a second through cavity that extends axially. The upper die core is embedded in the first segment and has an interference fit with the first outer sleeve body. The lower die core is embedded in the second through cavity and has an interference fit with the second outer sleeve body.

[0009] In the cold heading mold for core rod nails as described above, there is a gap between the outer wall of the second outer sleeve and the inner wall of the first outer sleeve.

[0010] As described above, in the cold heading mold for core rod heads, the inner diameter of the second outer sleeve is smaller than the inner diameter of the first segment, the inner edge of the end of the second outer sleeve protrudes from the inner wall of the first outer sleeve and forms a third limiting step, the end of the lower mold core is flush with the third limiting step, and the end of the upper mold core abuts against both the third limiting step and the end of the lower mold core.

[0011] The cold heading mold for core rod nail heads described above includes a stress dispersion structure at the first limiting step.

[0012] In the cold heading mold for core rod head as described above, the stress dispersion structure is a transition boss protruding toward the first cavity.

[0013] The cold heading die for the core rod head as described above, wherein the first cavity has a first draft taper.

[0014] The cold heading die for the core rod head as described above, wherein the second cavity has a second draft taper, and the first draft taper is greater than the second draft taper.

[0015] The cold heading die for the core rod head as described above, wherein the upper die core is an alloy steel upper die core and the lower die core is an alloy steel lower die core.

[0016] The cold heading die for the core rod head as described above, wherein the surfaces of the upper core and the lower core are covered with a nitrided layer.

[0017] Compared with the prior art, the present invention has the following features and advantages:

[0018] This utility model proposes a cold heading mold for mandrel heads, used for cold heading of mandrel heads. The mold has a separate upper and lower mold core. The head portion of the mandrel head is cold-headed in the first cavity of the upper mold core, and the mandrel portion is cold-headed in the second cavity of the lower mold core. During metal extrusion forming, air can be discharged along the gap between the upper and lower mold cores, allowing the metal to be fully filled in both cavities. This effectively eliminates surface defects at the mandrel head, thus meeting the requirements of the cold heading process. Simultaneously, the separate structure of the upper and lower mold cores effectively reduces stress concentration on the lower end face of the mandrel head portion, effectively extending the service life of the cold heading mold. Attached Figure Description

[0019] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, under the guidance of this invention, can select various possible shapes and proportions to implement this invention according to specific circumstances.

[0020] Figure 1 This is a schematic diagram of the structure of the cold heading mold for the core rod nail head of this utility model.

[0021] Explanation of reference numerals in the attached figures

[0022] 100. Cold heading mold for core rod nail heads; 10. Outer casing;

[0023] 11. First outer casing; 111. Second limiting step;

[0024] 12. Second outer casing; 121. Third limiting step;

[0025] 20. Upper mold core; 21. First cavity;

[0026] 30. Lower mold core; 31. Second cavity;

[0027] 40. First limiting step; α. First draft taper;

[0028] β, the second draft taper. Detailed Implementation

[0029] The details of this utility model can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of this utility model described herein are for illustrative purposes only and should not be construed as limiting the utility model in any way. Under the teachings of this utility model, those skilled in the art can conceive of any possible modifications based on this utility model, and these should all be considered to fall within the scope of this utility model.

[0030] Unless otherwise defined, the directions such as up, down, left, and right mentioned in this document refer to those shown in this utility model. Figure 1 The directions of up, down, left, and right are used as a reference, and will be explained here.

[0031] like Figure 1 As shown, this utility model proposes a cold heading mold 100 for core rod nail heads. The cold heading mold 100 for core rod nail heads includes an outer sleeve 10, an upper mold core 20, and a lower mold core 30. The outer sleeve 10 has an axially penetrating assembly cavity. The upper mold core 20 and the lower mold core 30 are both embedded in the assembly cavity and are interference-fitted with the outer sleeve 10. The upper mold core 20 has an axially penetrating first cavity 21, and the lower mold core 30 has an axially penetrating second cavity 31. The inner diameter of the second cavity 31 is smaller than the inner diameter of the first cavity 21. The lower mold core 30 abuts against the upper mold core 20, and the inner edge of the end of the lower mold core 30 protrudes from the inner wall of the upper mold core 20 and forms a first limiting step 40.

[0032] The present invention proposes a cold heading mold 100 for cold heading of mandrel heads. This mold 100 has a separate upper mold core 20 and a lower mold core 30. The head portion of the mandrel head is cold-headed in the first cavity 21 of the upper mold core 20, and the mandrel portion is cold-headed in the second cavity 31 of the lower mold core 30. During the metal extrusion process, air can be discharged along the gap between the upper mold core 20 and the lower mold core 30, allowing the metal to be fully filled in both the first and second cavities 21. This effectively eliminates surface defects at the mandrel head, thus meeting the requirements of the cold heading process. Simultaneously, the separate structure of the upper mold core 20 and the lower mold core 30 effectively reduces stress concentration on the lower end face of the mandrel head, effectively extending the service life of the cold heading mold 100.

[0033] In an optional embodiment of this utility model, the outer sleeve 10 has a first outer sleeve body 11 and a second outer sleeve body 12. The first outer sleeve body 11 has an axially penetrating first through cavity, which includes a first segment and a second segment. The inner diameter of the first segment is smaller than the inner diameter of the second segment, forming a second limiting step 111. The second outer sleeve body 12 passes through the second segment and abuts against the second limiting step 111. The second outer sleeve body 12 has an axially penetrating second through cavity. The upper mold core 20 is embedded in the first segment and has an interference fit with the first outer sleeve body 11. The lower mold core 30 is embedded in the second through cavity and has an interference fit with the second outer sleeve body 12. With the above structure, the outer sleeve 10 also adopts a split structure. The first outer sleeve body 11 applies radial pressure to the upper mold core 20, and the second outer sleeve body 12 applies radial pressure to the lower mold core 30. Different radial pressures can be provided to the upper mold core 20 and the lower mold core 30 according to the requirements of the cold heading process, effectively extending the service life of the upper mold core 20 and the lower mold core 30.

[0034] In an optional embodiment, a gap exists between the outer wall of the second outer sleeve 12 and the inner wall of the first outer sleeve 11. This gap allows air in the first cavity 21 and the second cavity 31 to escape more quickly, ensuring that the metal is fully filled in both cavities.

[0035] In one optional embodiment of this utility model, the first outer sleeve 11, the second outer sleeve 12, the upper mold core 20, and the lower mold core 30 are coaxially arranged.

[0036] In an optional embodiment, the inner diameter of the second outer sleeve 12 is smaller than that of the first segment. The inner edge of the end of the second outer sleeve 12 protrudes from the inner wall of the first outer sleeve 11 and forms a third limiting step 121. The end of the lower mold core 30 is flush with the third limiting step 121, and the end of the upper mold core 20 abuts against the third limiting step 121 and the end of the lower mold core 30, respectively. With the above structure, the first outer sleeve 11 fixes the second outer sleeve 12 through the second limiting step 111, and the second outer sleeve 12 forms a precise fit with the upper mold core 20 through the third limiting step 121, which improves the assembly accuracy of the core rod head cold heading mold 100 and extends the service life of the core rod head cold heading mold 100.

[0037] In one optional embodiment of this utility model, the upper mold core 20 and the lower mold core 30 are thermally assembled into the outer sleeve 10.

[0038] In one optional embodiment of this utility model, a stress dispersion structure is provided at the first limiting step 40 to avoid stress concentration and extend the service life of the mold.

[0039] In an optional example of this embodiment, the stress-dispersing structure is a transition boss protruding toward the first cavity 21.

[0040] In an optional embodiment of this invention, the first cavity 21 has a first draft taper α to achieve zero-damage demolding of the nail head and extend the life of the upper mold core 20.

[0041] In one optional embodiment of this implementation, the second cavity 31 has a second draft taper β, and the first draft taper α is greater than the second draft taper β, so as to achieve zero-damage demolding of the core rod and extend the life of the lower mold core 30.

[0042] In one optional example, the first draft taper α is 8 to 12 degrees, and the second draft taper β is 1 to 3 degrees.

[0043] Preferably, the first draft taper α is 10 degrees and the second draft taper β is 2 degrees.

[0044] In one optional embodiment of this utility model, the upper mold core 20 is an alloy steel upper mold core, and the lower mold core 30 is an alloy steel lower mold core.

[0045] In an optional example of this embodiment, the upper mold core 20 and the lower mold core 30 are made of SKH9 alloy steel.

[0046] In one optional embodiment of this utility model, the surfaces of the upper mold core 20 and the lower mold core 30 are respectively covered with a nitriding layer, and the hardness of the nitriding layer reaches HRC60 or above, which effectively improves the wear resistance and fatigue resistance of the upper mold core 20 and the lower mold core 30.

[0047] The cold heading mold 100 for core rod nail heads proposed in this utility model has an upper mold core 20 and a lower mold core 30, a first outer sleeve 11 and a second outer sleeve 12 forming a split structure, which can effectively improve the service life of the cold heading mold 100 for core rod nail heads.

[0048] The average lifespan of the cold heading die 100 for core rods proposed in this utility model can reach 13,000 to 15,000 core rods continuously, and the lifespan can be increased by 50% to 62%.

[0049] The cold heading die 100 for core rod nail heads proposed in this utility model can improve the continuity of the cold heading process, reduce the time for changing shapes, and reduce the manufacturing cost of core rods.

[0050] The detailed explanations of the above embodiments are intended only to explain the present invention so as to facilitate a better understanding of the present invention. However, these descriptions should not be construed as limiting the present invention for any reason. In particular, the various features described in different embodiments can be arbitrarily combined with each other to form other embodiments. Unless there is an explicit description to the contrary, these features should be understood to be applicable to any embodiment, and not limited to the described embodiments.

Claims

1. A cold heading forming die for a core pin nail head, characterized by, The cold heading die for the core rod head includes an outer sleeve, an upper die core, and a lower die core. The outer sleeve has an axially penetrating assembly cavity. The upper die core and the lower die core are both embedded in the assembly cavity and are interference-fitted with the outer sleeve. The upper die core has an axially penetrating first cavity, and the lower die core has an axially penetrating second cavity. The inner diameter of the second cavity is smaller than the inner diameter of the first cavity. The lower die core abuts against the upper die core, and the inner edge of the end of the lower die core protrudes from the inner wall of the upper die core, forming a first limiting step.

2. A cold header die for forming a stem peg head as defined in claim 1, wherein, The outer sleeve has a first outer sleeve body and a second outer sleeve body. The first outer sleeve body has a first through cavity that extends axially. The first through cavity includes a first segment and a second segment. The inner diameter of the first segment is smaller than the inner diameter of the second segment and forms a second limiting step. The second outer sleeve body passes through the second segment and abuts against the second limiting step. The second outer sleeve body has a second through cavity that extends axially. The upper mold core is embedded in the first segment and is interference-fitted with the first outer sleeve body. The lower mold core is embedded in the second through cavity and is interference-fitted with the second outer sleeve body.

3. A cold header die for forming a stem peg head as defined in claim 2, wherein, There is a gap between the outer wall of the second outer casing and the inner wall of the first outer casing.

4. The core pin stud head cold upset forming die of claim 2 wherein, The inner diameter of the second outer sleeve is smaller than the inner diameter of the first segment. The inner edge of the end of the second outer sleeve protrudes from the inner wall of the first outer sleeve and forms a third limiting step. The end of the lower mold core is flush with the third limiting step, and the end of the upper mold core abuts against both the third limiting step and the end of the lower mold core.

5. The core pin stud head cold upset forming die of claim 1 wherein, A stress-dispersing structure is provided at the first limiting step.

6. A cold header die for forming a stem peg head as defined in claim 5, wherein, The stress-dispersing structure is a transition boss that protrudes toward the first cavity.

7. The cold heading die for core rod heads as described in claim 1, characterized in that, The first cavity has a first draft taper.

8. A cold header die for forming a stem peg head as defined in claim 7, wherein, The second cavity has a second draft taper, and the first draft taper is greater than the second draft taper.

9. The core pin stud head cold upset forming die of claim 1 wherein, The upper mold core is an alloy steel upper mold core, and the lower mold core is an alloy steel lower mold core.

10. The core pin stud head cold upset forming die of claim 1 wherein, The surfaces of the upper mold core and the lower mold core are covered with a nitrided layer.

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