A cold heading method

Abstract

The present application discloses a cold heading method, the steps of which include: performing a first punching on a second intermediate obtained after shearing and positioning and grooving the upper and lower bottom surfaces to obtain a third intermediate, performing a second punching on the third intermediate through the cold heading machine to obtain a fourth intermediate, performing equal-diameter stretching on the fourth intermediate through the cold heading machine to obtain a fifth intermediate, and performing shape correction on the fifth intermediate through the cold heading machine to form the slender pipe fitting. By performing a first punching and a second punching on the blank to obtain an axially-shaped intermediate with two outer diameter sizes and a counterbore at the bottom, and performing equal-diameter stretching and then correction on the intermediate after the second punching by using the counterbore, the present application changes the existing upset forging process and realizes the preparation of the slender pipe fitting.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of mechanical processing, and more particularly, the present invention relates to a cold heading method. Background Art

[0002] Cold heading machine is a special equipment used for batch production of nuts, bolts and other fasteners. It can use the plastic deformation characteristics of metal itself at room temperature to perform forming operations such as upsetting and extrusion on metal blanks through dies. However, in the existing technology, the application of cold heading machine for the preparation of slender pipes faces challenges. The main reasons are as follows:

[0003] When the length of the pipe increases, if the traditional method of downward upsetting from the top of the blank is used to prepare the slender pipe, the front punch needs to move from the top of the blank to the bottom, which requires a slender front punch. However, the slender front punch is difficult to prepare, and it is difficult to ensure the coaxiality of the slender pipe using this upsetting method. At the same time, the front punch is prone to breakage during the downward movement of the front punch, which hinders the preparation process.

[0004] In view of this, how to use a cold heading machine to prepare slender pipes has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0005] In order to solve one or more of the above-mentioned technical problems, the present invention provides a cold heading method.

[0006] According to a first aspect of the present invention, a cold heading method is provided, which is applied to the preparation of a slender pipe with an inner diameter of 1.9-2.1 mm, an outer diameter of 3.95-4.05 mm, and a length of 25-40 mm, characterized in that the steps include:

[0007] Punching the second intermediate body obtained after shearing and positioning slotting once to obtain a third intermediate body, wherein the third intermediate body includes a first large diameter section having a first countersunk hole and a first small diameter section coaxially connected to the first large diameter section;

[0008] The third intermediate is subjected to secondary punching by the cold heading machine to obtain a fourth intermediate, wherein the fourth intermediate comprises a second large diameter section formed by extending the first large diameter section, a second small diameter section formed by extending the first small diameter section, a second countersunk hole formed in the second large diameter section and extended by the first countersunk hole, and a third countersunk hole formed in the second small diameter section and connected to the second countersunk hole, wherein the diameter of the third countersunk hole is smaller than the diameter of the second countersunk hole;

[0009] The fourth intermediate is subjected to equal-diameter stretching by the cold heading machine to obtain a fifth intermediate, wherein the fifth intermediate includes a rod-shaped structure and a sizing sinkhole formed within the rod-shaped structure and jointly formed by the third sinkhole and the reduced-diameter second sinkhole;

[0010] The fifth intermediate is subjected to shape correction by the cold heading machine to form the slender pipe fitting.

[0011] The second intermediate obtained after shearing and positioning and grooving the upper and lower bottom surfaces is subjected to a first punching to obtain a third intermediate, wherein the third intermediate includes a first large-diameter section having a first sinkhole and a first small-diameter section coaxially connected to the first large-diameter section;

[0012] The third intermediate is subjected to a second punching by the cold heading machine to obtain a fourth intermediate, wherein the fourth intermediate includes a second large-diameter section formed by extending the first large-diameter section, a second small-diameter section formed by extending the first small-diameter section, a second sinkhole formed within the second large-diameter section and formed by extending the first sinkhole, and a third sinkhole formed within the second small-diameter section and communicating with the second sinkhole, and the diameter of the third sinkhole is smaller than the diameter of the second sinkhole;

[0013] The fourth intermediate is subjected to equal-diameter stretching by the cold heading machine to obtain a fifth intermediate, wherein the fifth intermediate includes a rod-shaped structure and a sizing sinkhole formed within the rod-shaped structure and jointly formed by the third sinkhole and the reduced-diameter second sinkhole;

[0014] The fifth intermediate is subjected to shape correction by the cold heading machine to form the slender pipe fitting.

[0015] In one possible way, the cold heading machine uses a third front punching rod, a third die body, and a third rear punching rod to perform a first punching on the second intermediate. The third rear punching rod is embedded in the third die body, a third die cavity is formed between the third die body and the third rear punching rod, the third front punching rod is provided with a first-order support rod for forming the first sinkhole, and the third die cavity includes a first small-diameter cavity wall for forming the first small-diameter section and a first large-diameter cavity wall for forming the first large-diameter section;

[0016] The step of subjecting the second intermediate obtained after shearing and positioning and grooving the upper and lower bottom surfaces to a first punching to obtain the third intermediate includes:

[0017] Driving the third front punching rod to move so that the second intermediate in the third die cavity is cold-pressed and formed to obtain the third intermediate;

[0018] Driving the third rear punching rod to push the third intermediate out of the third die cavity.

[0019] One possible way is that the cold heading machine uses a fourth front punch bar, a fourth die body and a fourth rear punch bar to perform secondary punching on the third intermediate body. The fourth rear punch bar is embedded in the fourth die body, and a fourth die cavity is formed between the fourth die body and the fourth rear punch bar. The fourth front punch bar has a second-order strut for forming the second counterbore and the third counterbore. The fourth die cavity includes a second small-diameter cavity wall for forming the second small-diameter section and a second large-diameter cavity wall for forming the second large-diameter section;

[0020] The step of performing secondary punching on the third intermediate body through the cold heading machine to obtain the fourth intermediate body includes:

[0021] Driving the fourth front punch bar to perform cold pressing on the third intermediate body in the fourth die cavity to obtain the fourth intermediate body;

[0022] Driving the fourth rear punch bar to push the fourth intermediate body out of the fourth die cavity.

[0023] One possible way is that the cold heading machine uses a fifth front punch bar, a fifth die body and a fifth rear punch bar to perform equal-diameter stretching on the fourth intermediate body. The fifth front punch bar has a first strut portion for forming the sizing counterbore. The fifth die cavity includes a first constant-diameter section, a second constant-diameter section with a radial dimension not less than that of the first constant-diameter section, and a reduced-diameter section connecting the first constant-diameter section and the second constant-diameter section;

[0024] The step of performing equal-diameter stretching on the fourth intermediate body through the cold heading machine using the third counterbore to obtain the fifth intermediate body includes:

[0025] Driving the fifth front punch bar to move until it abuts against the third counterbore;

[0026] Driving the fifth front punch bar to push the fourth intermediate body placed in the second constant-diameter section to form the fifth intermediate body;

[0027] Driving the fifth rear punch bar to move to push the fifth intermediate body out of the fifth die cavity;

[0028] During the process of driving the fifth front punch bar to push the fourth intermediate body placed in the second constant-diameter section until the fifth front punch bar moves to the bottom of the second constant-diameter section to form the fifth intermediate body, the fifth rear punch bar is located below the second constant-diameter section, and the reduced-diameter section squeezes and contracts the second large-diameter section of the fourth intermediate body.

[0029] One possible way is that the step of performing shape correction on the fifth intermediate body through the cold heading machine to form the slender pipe fitting includes:

[0030] Invert the fifth intermediate and perform straightening treatment on it using a cold heading machine to form a sixth intermediate, where the sixth intermediate includes a pipe fitting structure with an internal plugging.

[0031] Use the cold heading machine to punch out the plugging to form the slender pipe fitting.

[0032] In one possible way, the cold heading machine uses a sixth forward punch rod, a sixth die body, and a sixth rear punch rod to perform straightening treatment on the inverted fifth intermediate. The sixth die body and the sixth rear punch rod form a sixth die cavity. The sixth forward punch rod is provided with a second rod portion for forming the plugging, and the sixth die cavity is used for forming the pipe fitting structure.

[0033] The step of inverting the fifth intermediate and performing straightening treatment on it using a cold heading machine to form a sixth intermediate includes:

[0034] Drive the sixth forward punch rod to perform cold pressing on the fifth intermediate inverted in the sixth die cavity, and use the second rod portion to form the plugging to form the sixth intermediate.

[0035] Drive the sixth forward punch rod to push the sixth intermediate out of the sixth die cavity.

[0036] In one possible way, the cold heading machine uses a seventh forward punch rod provided with a channel, a seventh die body, and a seventh rear punch rod to punch out the plugging, and uses a support assembly coaxial with the seventh rear punch rod, a thimble arranged in a through hole of the support assembly, and a push rod assembly located above the support assembly to demold the slender pipe fitting. The seventh die body and the seventh rear punch rod form a seventh die cavity.

[0037] The step of using the cold heading machine to punch out the plugging to form the slender pipe fitting includes:

[0038] Drive the seventh forward punch rod to move downward so that the plugging is discharged from the channel.

[0039] Drive the thimble to move so that the push rod assembly moves axially along the seventh rear punch rod to push out the slender pipe fitting.

[0040] In one possible way, before the step of performing a first punching on the second intermediate obtained by passing the sheared columnar blank through a cold heading machine to obtain a third intermediate, the method further includes:

[0041] Perform upsetting treatment on the target blank sheared by the cold heading machine to form a first intermediate. A first chamfer is provided on a first end face of the first intermediate, and a first positioning groove is provided on a second end face of the first intermediate.

[0042] Invert the first intermediate body, and use a cold heading machine to perform grooving treatment on the first intermediate body to form a second intermediate body. The second intermediate body includes a second positioning groove provided on the first end face and a third positioning groove provided on the second end face. A second chamfer is formed around the second positioning groove.

[0043] In one possible way, the cold heading machine uses a first die body, a first front punch rod, and a first back punch rod to perform upsetting treatment on the sheared target blank. The first die body and the first back punch rod form a first die cavity. The bottom of the cavity wall of the first die cavity has a first conical surface for forming the first chamfer, and the pressing end of the first front punch rod has a first convex platform for forming the first positioning groove.

[0044] The steps of performing upsetting and grooving treatment on the sheared target blank by the cold heading machine to form the first intermediate body include:

[0045] Drive the first front punch rod to push the sheared target blank placed in the first die cavity, and obtain the first intermediate body through cold pressing.

[0046] Drive the first back punch rod to push the first intermediate body out of the first die cavity.

[0047] In one possible way, in the step of inverting the first intermediate body and using a cold heading machine to perform grooving treatment on the first intermediate body to form a second intermediate body, the cold heading machine uses a second die body, a second front punch rod, and a second back punch rod to perform grooving treatment on the first intermediate body. The second die body and the second back punch rod form a second die cavity. The pressing end of the second front punch rod is provided with a second convex platform for forming the second positioning groove and the second chamfer, and the bottom of the cavity wall of the second die cavity is provided with a second conical surface for forming the third positioning groove.

[0048] The process of performing upsetting and grooving treatment on the sheared target blank by the cold heading machine to form the first intermediate body includes:

[0049] Drive the second front punch rod to push the first intermediate body placed in the second die cavity, and form the second intermediate body through cold pressing.

[0050] Drive the second back punch rod to push the second intermediate body out of the second die cavity.

[0051] In this application, by sequentially performing primary punching and secondary punching on the blank, a shaft-shaped intermediate body with two outer diameter sizes and a counterbore at the bottom is obtained. After equal-diameter stretching and straightening of the intermediate body after secondary punching using the counterbore, the existing upsetting and forging process is changed to realize the preparation of slender pipe fittings. Description of the Drawings

[0052] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features, and advantages of the exemplary embodiments of the present invention will become readily understood. In the drawings, several embodiments of the present invention are shown in an exemplary rather than restrictive manner, and the same or corresponding reference numerals denote the same or corresponding parts, wherein:

[0053] Figure 1 It is a flowchart of a cold heading method provided by an embodiment of the present invention;

[0054] Figure 2(a) is a sectional view of the third intermediate body of an embodiment of the present invention;

[0055] Figure 2(b) shows a sectional view of the cold heading machine for preparing the third intermediate body shown in Figure 2(a);

[0056] Figure 3(a) is a sectional view of the fourth intermediate body of an embodiment of the present invention;

[0057] Figure 3(b) shows a sectional view of the cold heading machine for preparing the fourth intermediate body shown in Figure 3(a);

[0058] Figure 4(a) is a sectional view of the fifth intermediate body of an embodiment of the present invention;

[0059] Figure 4(b) shows a sectional view of the cold heading machine for preparing the fifth intermediate body shown in Figure 4(a);

[0060] Figure 5(a) is a sectional view of the sixth intermediate body of an embodiment of the present invention;

[0061] Figure 5(b) shows a sectional view of the cold heading machine for preparing the sixth intermediate body shown in Figure 5(a);

[0062] Figure 6(a) is a sectional view of the slender pipe fitting of an embodiment of the present invention;

[0063] Figure 6(b) shows a sectional view of the cold heading machine for preparing the slender pipe fitting shown in Figure 6(a);

[0064] Figure 7 It is a schematic diagram of a cold heading method shown in the present invention;

[0065] Figure 8 It is another flowchart of the cold heading method shown in the present invention;

[0066] Figure 9(a) is a sectional view of the target blank after shearing of an embodiment of the present invention;

[0067] Figure 9(b) shows a sectional view of the cold heading machine for preparing the target blank after shearing shown in Figure 9(a);

[0068] Figure 10(a) is a sectional view of the first intermediate body of an embodiment of the present invention;

[0069] Figure 10(b) shows a cross-sectional view of a cold heading machine for preparing the first intermediate shown in Figure 10(a);

[0070] Figure 11(a) is a cross-sectional view of the second intermediate of an embodiment of the present invention;

[0071] Figure 11(b) shows a cross-sectional view of a cold heading machine for preparing the second intermediate shown in Figure 11(a);

[0072] Description of reference numerals:

[0073] 10. First intermediate; 11. First positioning groove; 12. First chamfer; 13. First front punching rod; 14. First rear punching rod; 15. First die cavity; 16. First boss; 17. First conical surface; 18. First die body; 20. Second intermediate; 21. Second positioning groove; 22. Second chamfer; 23. Third positioning groove; 24. Second front punching rod; 25. Second rear punching rod; 26. Second die body; 27. Second die cavity; 28. Second boss; 29. Second conical surface; 30. Third intermediate; 31. First counterbore; 32. First small diameter section; 33. First large diameter section; 34. Third rear punching rod; 35. Third die body; 36. First order support rod; 37. Third die cavity; 371. First large diameter cavity wall; 372. First small diameter cavity wall; 38. Third front punching rod; 40. Fourth intermediate; 41. Second small diameter section; 42. Second counterbore; 43. Second large diameter section; 44. Third counterbore; 45. Fourth front punching rod; 46. Second order support rod; 47. Fourth die body; 48. Fourth die cavity; 481. Second large diameter cavity wall; 482. Second small diameter cavity wall; 49. Fourth rear punching rod; 50. Fifth intermediate; 51. Rod-shaped structure; 52. Sizing counterbore; 53. Fifth front punching rod; 54. First support rod part; 55. Fifth die cavity; 551. First constant diameter section; 552. Reducing diameter section; 553. Second constant diameter section; 56. Fifth die body; 57. Fifth rear punching rod; 60. Sixth intermediate; 61. Pipe fitting structure; 62. Plug; 63. Sixth front punching rod; 64. Second support rod part; 65. Sixth die body; 66. Sixth die cavity; 67. Sixth rear punching rod; 70. Elongated pipe fitting; 71. Seventh front punching rod; 71a. Channel; 72. Seventh rear punching rod; 73. Seventh die body; 74a. First cushion block; 74b. Second cushion block; 74. Support assembly; 75. Thimble; 76. Through hole; 77a. Three-hole middle piece; 77b. Single-hole middle piece; 77. Push rod assembly; 78. Seventh die cavity. Detailed implementation manners

[0074] Next, in combination with the accompanying drawings in the embodiments of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present disclosure.

[0075] A cold heading machine is a special equipment dedicated to mass-producing fasteners such as nuts and bolts. It can use the plastic deformation characteristics of the metal itself at room temperature to perform forming operations such as upsetting and extrusion on the metal blank through a mold. However, in the prior art, for the preparation of slender pipe fittings, the application of the cold heading machine faces challenges, mainly for the following reasons:

[0076] When the length of the pipe fitting increases, if the traditional downward upsetting method from the top of the blank is used to prepare the slender pipe fitting, the forward punch needs to move from the top of the blank to the bottom. This upsetting method is difficult to ensure the coaxiality of the slender pipe fitting. At the same time, during the downward movement of the forward punch, it is easy to break, resulting in the obstruction of the preparation process.

[0077] To solve the above problems, the present application provides a cold heading method, which is applied to the preparation of slender pipe fittings. The inner diameter of the slender pipe fitting is 1.9 - 2.1 mm, the outer diameter is 3.95 - 4.05 mm, and the length is 25 - 40 mm. To achieve the preparation of the slender pipe fitting, refer to Figure 1 , specifically including the following steps:

[0078] S102: Perform a first punching on the second intermediate body obtained after shearing and positioning and grooving the upper and lower bottom surfaces to obtain a third intermediate body.

[0079] Specifically, the third intermediate body 30 includes a first large-diameter section 33 and a first small-diameter section 32, and the first large-diameter section 33 and the first small-diameter section 32 are coaxially connected. The first large-diameter section 33 has a first counterbore 31.

[0080] In other words, the third intermediate body 30 is composed of two pipe fittings with different radii. As can be seen from Figure 2(a), the radius of the upper pipe fitting of the third intermediate body 30 is greater than that of the lower pipe fitting, and the upper pipe fitting of the third intermediate body 30 is provided with a counterbore (i.e., the first counterbore 31).

[0081] Through the above method, the first punching is achieved.

[0082] S104: Perform a second punching on the third intermediate body through a cold heading machine to obtain a fourth intermediate body.

[0083] Referring to Fig. 3(a), specifically, in this step, the fourth intermediate 40 includes a second large-diameter section 43 and a second small-diameter section 41. The second large-diameter section 43 is formed by extending the first large-diameter section 33 of the third intermediate 30 shown in Fig. 2(a) above. The second small-diameter section 41 is formed by extending the first small-diameter section 32 of the third intermediate 30 shown in Fig. 2(a) above. In addition, the fourth intermediate 40 further includes a second counterbore 42 and a third counterbore 44. The second counterbore 42 is formed by extending the first counterbore 31 shown in Fig. 2(a) above, and the second counterbore 42 is formed within the aforementioned second large-diameter section 43 and communicates with the third counterbore 44. The third counterbore 44 is formed within the second small-diameter section 41. As can be seen from Fig. 3(a), the diameter of the third counterbore 44 is smaller than the diameter of the second counterbore 42.

[0084] In this application, no specific limitations are made herein regarding the radii of the second counterbore 42, the third counterbore 44, the second large-diameter section 43, and the second small-diameter section 41.

[0085] S106: The fourth intermediate is subjected to equal-diameter stretching through a cold heading machine using the third counterbore to obtain a fifth intermediate.

[0086] In this application, referring to Fig. 4(a), the fifth intermediate 50 includes a rod-shaped structure 51 and a sizing counterbore 52. The sizing counterbore 52 is formed within the rod-shaped structure 51 and is jointly formed by the third counterbore 44 and the reduced-diameter second counterbore 42 in Fig. 3(a).

[0087] Combined with the above, the fourth intermediate 40 includes a second counterbore 42 and a third counterbore 44. Pressure is applied at the third counterbore 44 of the fourth intermediate 40 to longitudinally stretch the third intermediate 30. The sizes of the second counterbore 42 and the second large-diameter section gradually become smaller, and finally a rod-shaped structure 51 with a counterbore at the bottom is obtained. Referring to Fig. 4(a), each cross-section of the rod-shaped structure 51 has the same outer diameter size and inner diameter size.

[0088] S108: The fifth intermediate is subjected to shape correction through a cold heading machine to form an elongated pipe fitting.

[0089] Based on the above, by performing shape correction on the fifth intermediate, the elongated pipe fitting can be prepared.

[0090] In this application, by performing a first punching and a second punching on the blank, a shaft-shaped intermediate with two outer diameter sizes and a counterbore at the bottom is obtained. After equal-diameter stretching and correction of the intermediate after the second punching using the counterbore, the existing upsetting forging process is changed to achieve the preparation of the elongated pipe fitting.

[0091] The following will specifically elaborate on the steps of S102 to S108 above:

[0092] In S102: In the step of performing a first punching on the second intermediate 20 obtained after shearing and positioning slotting to obtain the third intermediate 30, referring to FIGS. 2(a) and 2(b), it can be seen that the cold heading machine uses the third front punching rod 38, the third die body 35, and the third rear punching rod 34 to perform a first punching on the second intermediate 20. A first-order support rod 36 is provided at the bottom of the third front punching rod 38, and the first-order support rod 36 is used to form the first counterbore 31.

[0093] The third rear punching rod 34 is embedded in the third die body 35, and a third die cavity 37 is formed between the third die body 35 and the third rear punching rod 34. In order to be able to form the first large-diameter section 33 and the first small-diameter section 32, the third die cavity 37 includes a first small-diameter cavity wall 372 channel and a first large-diameter cavity wall 371. During the cold pressing process, the first large-diameter cavity wall 371 is specifically used to form the first large-diameter section 33, and the first small-diameter cavity wall 372 is specifically used to form the first small-diameter section 32.

[0094] In some embodiments, first, the third front punching rod 38 is driven to move so that the second intermediate 20 located in the third die cavity 37 deforms. At this time, under the action of the third die body 35, the second intermediate placed in the third die cavity 37 is extruded and deformed. Specifically, the third front punching rod 38 moves downward to form the first counterbore 31. The blank outside the first counterbore 31 radially diffuses to form the aforementioned third intermediate 30.

[0095] At this time, the third intermediate 30 is still in the third die cavity 37. In order to separate the third intermediate 30 from the third die cavity 37, at this time, the third rear punching rod 34 is driven to move upward to push the third intermediate 30 out of the third die cavity 37. Thus, a first punching process is completed.

[0096] It should be noted that the above steps of the first punching are only one achievable method provided by this application, and those skilled in the art performing a first punching on the blank by referring to other methods are also included in the protection scope of this application.

[0097] Continuing to refer to FIG. 2(b), in order to achieve the positioning of the blank, in still some other embodiments, a convex platform matching the positioning groove on the upper surface of the second intermediate 20 is provided at the bottom of the aforementioned third front punching rod 38, and a convex platform matching the positioning groove on the lower surface of the second intermediate 20 is provided at the top of the third rear punching rod 34. By using the cooperation of the convex platform and the positioning groove, the positioning of the second intermediate 20 can be achieved, improving the precision of cold pressing.

[0098] In S104: In the step of performing a second punching on the third intermediate 30 through a cold heading machine to obtain the fourth intermediate 40, in some embodiments, referring to FIGS. 2(b) and 3(b), it can be seen that the cold heading machine uses the fourth front punching rod 45, the fourth die body 47, and the fourth rear punching rod 49 to perform a second punching on the third intermediate 30.

[0099] Combined with Fig. 3(b), it can be seen that the fourth post-punching rod 49 is embedded in the fourth die body 47, and a fourth die cavity 48 is formed between the fourth die body 47 and the fourth post-punching rod 49. The fourth pre-punching rod 45 and the second-order support rod 46 are provided, and the second-order support rod 46 is specifically used for forming the second counterbore 42 and the third counterbore 44. The fourth die cavity 48 includes a second small-diameter cavity wall 482 and a second large-diameter cavity wall 481. The second small-diameter cavity wall 482 is used for forming the second small-diameter section 41, and the second large-diameter cavity wall 481 is used for forming the second large-diameter section 43.

[0100] In this step, first, the fourth pre-punching rod 45 is driven to perform cold pressing on the third intermediate body 30 in the fourth die cavity 48, and the fourth intermediate body 40 is obtained.

[0101] When the fourth pre-punching rod 45 moves downward, under the action of the second-order support rod 46, the fourth die cavity 48 extends the first counterbore 31 of the third intermediate body 30 shown in Fig. 3(a) to form the second counterbore 42, and the third intermediate body 30 forms the third counterbore 44 under the action of the second-order support rod 46. Under the action of the downward movement of the fourth pre-punching rod 45, the third intermediate body 30 of the fourth die cavity 48 is along the radial outer edge, and under the action of the second small-diameter cavity wall 482 and the second large-diameter cavity wall 481, the second large-diameter section 43 and the second small-diameter section 41 are respectively formed, and thus the fourth intermediate body 40 is obtained.

[0102] When the fourth intermediate body 40 is formed, at this time the fourth intermediate body 40 is still in the fourth die cavity 48. In order to realize the demolding of the fourth intermediate body 40, the sixth pre-punching rod 63 is driven to push the sixth intermediate body out of the sixth die cavity 66.

[0103] On the basis of the foregoing embodiment, referring to Fig. 3(b), positioning grooves are provided on both the upper and lower bottom surfaces in the second intermediate body 20 after grooving, and in the foregoing step of one-time punching, the existence of its positioning grooves is not affected. Thus, it can be seen that positioning grooves are provided on both the upper and lower bottom surfaces of the third intermediate body 30.

[0104] Based on this, in some other embodiments, a boss is provided on the fourth pre-punching rod 45 that cooperates with the positioning groove on the upper surface of the third intermediate body 30, and a boss is provided on the fourth post-punching rod 49 that cooperates with the positioning groove on the lower surface of the third intermediate body 30. By using the cooperation of the boss and the positioning groove, the positioning of the third intermediate body 30 can be realized, and the precision of cold pressing is improved.

[0105] In step S106: In the step of obtaining the fifth intermediate body 50 by equal-diameter stretching of the fourth intermediate body through a cold heading machine using the third counterbore, referring to Fig. 4(a) and Fig. 4(b), in some embodiments, the cold heading machine uses the fifth pre-punching rod 53, the fifth die body 56 and the fifth post-punching rod 57 to perform equal-diameter stretching on the fourth intermediate body 40.

[0106] The fifth forward punch 53 has a first rod portion 54 which is specifically used for forming a sizing counterbore 52. The fifth cavity 55 includes a first constant-diameter section 551, a second constant-diameter section 553, and a reduced-diameter section 552. The reduced-diameter section 552 is located between the first constant-diameter section 551 and the second constant-diameter section 553 and connects the first constant-diameter section 551 and the second constant-diameter section 553. The radial dimension of the second constant-diameter section 553 is not less than that of the first constant-diameter section 551.

[0107] In this step, first, the fifth forward punch 53 is driven downward until it abuts against the third counterbore 44.

[0108] Then, the fifth forward punch 53 is driven to push the fourth intermediate body 40 placed in the second constant-diameter section 553. The fourth intermediate body 40 moves downward. During this process, the fifth backward punch 57 is located below the second constant-diameter section 553. The reduced-diameter section 552 squeezes and contracts the second large-diameter section 43 of the fourth intermediate body 40 to form a rod-shaped structure 51, and the first rod portion 54 of the fifth forward punch 53 is used to form a sizing counterbore 52. Through this step, equal-diameter stretching is achieved, and the fifth intermediate body 50 is formed.

[0109] It should be noted that during this process, the fifth backward punch 57 is located below the second constant-diameter section 553 and does not contact the fourth intermediate body 40.

[0110] At this time, the fifth intermediate body 50 is still located in the fifth cavity 55. By driving the fifth backward punch 57 upward to push the fifth intermediate body 50 out of the fifth cavity 55, demolding of the fifth intermediate body 50 can be achieved.

[0111] Based on the foregoing, referring to Fig. 4(b), after positioning and grooving, positioning grooves can be provided on the upper and lower surfaces of the second intermediate body 20. Combining the foregoing steps, positioning grooves are provided on both the upper and lower surfaces of the fifth intermediate body 50 on the premise that the existence of the positioning grooves is not affected by the first punching and the second punching.

[0112] Based on this, in some other embodiments, a boss matching the positioning groove located on the upper surface of the fourth intermediate body 40 is provided on the fifth forward punch 53, and a boss matching the positioning groove located on the lower surface of the fourth intermediate body 40 is provided on the fifth backward punch 57. By using the cooperation of the boss and the positioning groove, positioning of the fourth intermediate body 40 can be achieved, and the precision of cold pressing forming is improved.

[0113] In this way, when preparing a slender pipe fitting, it is not necessary to prepare a slender forward punch, and it is easy to ensure the coaxiality of the slender pipe fitting, and the forward punch is not easily broken during the cold pressing forming process.

[0114] In step S108: shaping the fifth intermediate through a cold heading machine to form an elongated pipe fitting, in order to improve the coaxiality of the elongated pipe fitting, referring to FIGS. 4(a), 5(a) and 5(b), first execute S108a: invert the fifth intermediate 50, at this time the sizing counterbore 52 located at the bottom of the fifth intermediate 50 is flipped to the top of the fifth intermediate 50, and at this time, perform straightening treatment with a cold heading machine to form the sixth intermediate 60. Specifically, the sixth intermediate 60 includes a pipe fitting structure 61 with an internal plug 62.

[0115] Through this step, that is, re-straightening the obtained sixth intermediate 60, the coaxiality of the elongated pipe fitting is improved.

[0116] After obtaining the sixth intermediate 60, execute S108b: use a cold heading machine to punch out the plug to form an elongated pipe fitting.

[0117] Through this step, the waste of the elongated sixth intermediate 60 is discharged, and the preparation of the elongated pipe fitting is realized.

[0118] Specifically, referring to FIG. 5(b), in S108a, the cold heading machine uses a sixth front punch 63, a sixth die body 65 and a sixth rear punch 67 to perform straightening treatment on the inverted fifth intermediate. The sixth die body 65 and the sixth rear punch 67 form a sixth die cavity 66. The sixth rear punch 67 and the sixth die body 65 together form the sixth die cavity 66. The sixth front punch 63 is provided with a second support rod portion 64, and this second support rod portion 64 is used to form the plug 62.

[0119] In this step, first, drive the sixth front punch 63 to cold press the fifth intermediate 50 inverted in the sixth die cavity 66. Under the extrusion of the sixth front punch 63, use the second support rod portion 64 to form the plug 62 to form the sixth intermediate 60. At this time, the sixth intermediate 60 is still in the sixth die cavity 66. Drive the sixth front punch 63 to push out the sixth intermediate shown in FIG. 5(a) from the sixth die cavity 66, and then the sixth intermediate 60 can be obtained.

[0120] Through the above method, the fifth intermediate 50 can be further corrected, and the coaxiality of the elongated pipe fitting is improved.

[0121] Referring to FIGS. 5(a) and 6(b), in step S108b: using a cold heading machine to punch out the plug to form an elongated pipe fitting, first place the sixth intermediate in the seventh die body 73. The cold heading machine uses a seventh front punch 71 to punch out the plug 62. Specifically, the seventh front punch is provided with a channel 71a. When the seventh front punch 71 moves downward, the channel 71 discharges the excess waste to obtain the elongated pipe fitting shown in FIG. 6(a). Separate the elongated pipe fitting shown in 5(a) from the seventh die cavity 78, and then the elongated pipe fitting shown in 6(a) can be obtained.

[0122] It should be noted that the seventh die cavity 78 is formed by the seventh back punch 72 and the seventh die body 73.

[0123] In some embodiments, the height of the head of the back punch is relatively high. At this time, if the back punch is used alone to push out the slender pipe fitting, it is easy for the slender pipe fitting to be sleeved around the rod head, and the separation of the slender pipe fitting from the rod head cannot be achieved.

[0124] To solve this problem, the cold heading machine uses a support assembly, a thimble, and a push rod assembly to demold the slender pipe fitting.

[0125] Specifically, the support assembly 74 is wrapped around the seventh back punch 72 and is coaxial with the seventh back punch 72. The support assembly 74 is provided with a through hole 76. A thimble 75 is arranged in the through hole 76. A screw rod (not shown in the figure) can be arranged inside the thimble 75 so that the thimble 75 can move axially along the through hole 76. A push rod assembly 77 is arranged on the support assembly 74.

[0126] After the seventh front punch punches out the plug 62, the screw rod is used to drive the aforementioned thimble 75 to move in the channel, and then drive the push rod assembly 77 to push the slender pipe fitting in Fig. 6(a) to move, so that the slender pipe fitting is separated from the rod head of the seventh back punch, realizing demolding in the case of a relatively high rod head of the back punch.

[0127] Combined with Fig. 6(b), exemplarily, the support assembly 74 includes a first cushion block 74a and a second cushion block 74b. The first cushion block 74a is located below the seventh die body 73 and is provided with a through hole 76. The second cushion block 74b is located between the first cushion block 74a and the seventh die body 73. The push rod assembly includes a three-hole middle piece 77a and a single-hole middle piece 77b. The three-hole middle piece 77a is located below the single-hole middle piece 77b and is used to push out the slender rod member in Fig. 6(a).

[0128] When the thimble moves, it drives the three-hole middle piece and the single-hole middle piece to move, and then demolds the slender rod member.

[0129] It can be seen that in this embodiment, in the step of using a cold heading machine to punch out the plug to form a slender pipe fitting in S108b, first, drive the seventh front punch to move downward so that the plug 62 shown in Fig. 5(a) is discharged from the channel, and then drive the thimble to move so that the push rod assembly moves axially along the seventh back punch to push out the slender pipe fitting.

[0130] Through the above implementation manner, demolding can be achieved in the case of a relatively high rod head of the back punch.

[0131] Referring to Figure 7 and Figure 8 , another cold heading method provided by the embodiment of the present application specifically includes the following steps:

[0132] S202: Upset the target blank after shearing by a cold heading machine to form a first intermediate.

[0133] Specifically, referring to Fig. 10(a), a first chamfer 12 is provided on the first end face of the first intermediate 10, and a first positioning groove 11 is provided on the second end face of the first intermediate 10.

[0134] To obtain the first intermediate 10, it is necessary to shear the target blank using the die shown in Fig. 9(b) to obtain the blank shown in Fig. 9(a).

[0135] Then, referring to Fig. 10(b), the cold heading machine uses the first die body 18, the first front punch 13 and the first back punch 14 to upset the sheared target blank. The first die body 18 and the first back punch 14 form a first die cavity 15. The bottom of the cavity wall of the first die cavity 15 has a first conical surface 17, and the first conical surface 17 is specifically used to form the aforementioned first chamfer 12. The first front punch 13 has a first boss 16, and the first boss 16 is specifically used to form the first positioning groove 11.

[0136] Finally, drive the first front punch 13 to push the sheared target blank placed in the first die cavity 15, and obtain the first intermediate through cold pressing. At this time, under the action of the first front punch 13 and the first die cavity 15, the first intermediate is formed. Finally, drive the first back punch 14 to push the first intermediate out of the first die cavity 15, and the first intermediate 10 can be obtained.

[0137] S204: Invert the first intermediate, and use a cold heading machine to perform grooving treatment on the second end face of the first intermediate to form a second intermediate.

[0138] Specifically, referring to Fig. 11(a), the second intermediate 20 includes a second positioning groove 21 provided on the first end face and a third positioning groove 23 provided on the second end face. A second chamfer 22 is provided around the second positioning groove 21.

[0139] In this step, the cold heading machine uses the second die body 26, the second front punch 24 and the second back punch 25 to perform grooving treatment on the first intermediate 10 in Fig. 10(a). The second die body 26 and the first back punch 14 form a second die cavity 27. A second boss 28 is provided at the pressing end of the second front punch 24, and the second boss 28 is used to form the second positioning groove 21 and the second chamfer 22. A second conical surface 29 is provided at the bottom of the cavity wall of the second die cavity 27, and the second conical surface 29 is used to form the third positioning groove 23.

[0140] Specifically, to obtain the second positioning body 20, first, drive the second forward punch rod 24 to push the first intermediate body placed in the second die cavity 27. At this time, under the action of the second forward punch rod 24 and the second die cavity 27, the second intermediate body 20 is formed by cold pressing. Then, drive the first backward punch rod 14 to push the first intermediate body shown in Fig. 10(a) out of the second die cavity 27.

[0141] By upsetting the blank and then grooving it, the pre-treatment of the sheared blank can reduce the burrs of the sheared blank and improve the flatness of the blank.

[0142] S206: Punch the second intermediate body obtained after shearing and positioning and grooving the upper and lower bottom surfaces once to obtain the third intermediate body.

[0143] S208: Punch the third intermediate body twice through a cold heading machine to obtain the fourth intermediate body.

[0144] S210: Equal-diameter stretch the fourth intermediate body 40 through a cold heading machine to obtain the fifth intermediate body.

[0145] S212: Shape-correct the fifth intermediate body 50 through a cold heading machine to form a slender pipe fitting.

[0146] Regarding the steps of S206 to S212, please refer to the aforementioned S102 to S108. The beneficial effects can be specifically referred to S102 to S108 and will not be elaborated here.

[0147] On the basis of all the foregoing embodiments, in this application, all the die bodies can be made of alloy materials, that is, the first die body to the seventh die body are all made of alloy materials. In this way, it is possible to prevent the blank from wearing the die body during the upsetting forging process.

[0148] This application has the following beneficial effects:

[0149] 1. By punching the blank once and twice, an axially intermediate body with two outer diameter sizes and a counterbore at the bottom is obtained. After equal-diameter stretching and straightening the intermediate body after the second punching using the counterbore, the preparation of a slender pipe fitting is realized by changing the existing upsetting forging process.

[0150] 2. Upset the blank and then groove it. The pre-treatment of the sheared blank can reduce the burrs of the sheared blank and improve the flatness of the blank.

[0151] 3. When demolding the slender pipe fitting, use the ejector pin to drive the push rod assembly to move, preventing the slender pipe fitting from covering the rod head of the backward punch rod during demolding.

[0152] In the foregoing description of the present application, unless otherwise clearly specified and defined, terms such as "fixed", "installed", "connected" or "coupled" should be understood in a broad sense. For example, with respect to the term "connected", it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, or it can be the communication inside two elements or the interaction relationship between two elements. Therefore, unless otherwise clearly defined in the present application, those skilled in the art can understand the specific meanings of the above terms in the present invention according to specific circumstances.

[0153] Based on the foregoing description of the present application, those skilled in the art can also understand the following terms used, such as "upper", "lower", "front", "rear", "left", "right", "length", "width", "thickness", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", etc. Terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the drawings of the present application. They are only for the purpose of facilitating the description of the solution of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the devices or elements involved must have the specific orientation, be constructed and operated in the specific orientation. Therefore, the above terms of orientation or positional relationships cannot be understood or interpreted as limitations on the solution of the present invention.

[0154] In addition, terms such as "first" or "second" used in the present application to refer to numbers or ordinals are only for descriptive purposes and cannot be understood as explicitly or implicitly indicating relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically defined.

[0155] Although multiple embodiments of the present invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art can envision many variations, alterations, and alternative ways without departing from the spirit and scope of the present invention. It should be understood that various alternatives to the embodiments of the present invention described herein may be employed in practicing the present invention. The appended claims are intended to define the scope of the present invention and thus cover equivalents or alternatives within the scope of these claims.

Claims

1. A cold heading method, characterized in that, The cold heading method is used for the preparation of slender pipe fittings with an inner diameter of 1.9 - 2.1 mm, an outer diameter of 3.95 - 4.05 mm, and a length of 25 - 40 mm. It is characterized in that the steps include: Performing a first punching on the second intermediate obtained after shearing and positioning and grooving the upper and lower bottom surfaces to obtain a third intermediate. Wherein, the third intermediate includes a first large-diameter section having a first counterbore and a first small-diameter section coaxially connected to the first large-diameter section; Performing a second punching on the third intermediate through a cold heading machine to obtain a fourth intermediate. Wherein, the fourth intermediate includes a second large-diameter section formed by extending the first large-diameter section, a second small-diameter section formed by extending the first small-diameter section, a second counterbore formed in the second large-diameter section and extended from the first counterbore, and a third counterbore formed in the second small-diameter section and communicating with the second counterbore, and the diameter of the third counterbore is smaller than the diameter of the second counterbore; Performing equal-diameter stretching on the fourth intermediate through the cold heading machine to obtain a fifth intermediate. Wherein, the fifth intermediate includes a rod-shaped structure and a sizing counterbore formed in the rod-shaped structure and jointly formed by the third counterbore and the reduced-diameter second counterbore; Performing shape correction on the fifth intermediate through the cold heading machine to form the slender pipe fitting; The cold heading machine uses a fifth front punch, a fifth die body, and a fifth rear punch to perform equal-diameter stretching on the fourth intermediate. The fifth front punch has a first rod portion for forming the sizing counterbore. The fifth die cavity includes a first constant-diameter section, a second constant-diameter section with a radial dimension not less than that of the first constant-diameter section, and a reduced-diameter section connecting the first constant-diameter section and the second constant-diameter section; The step of performing equal-diameter stretching on the fourth intermediate through the cold heading machine using the third counterbore to obtain the fifth intermediate includes: Driving the fifth front punch to move until it abuts against the third counterbore; Driving the fifth front punch to push the fourth intermediate placed in the second constant-diameter section to form the fifth intermediate; Driving the fifth rear punch to move to push the fifth intermediate out of the fifth die cavity; During the process of driving the fifth front punch to push the fourth intermediate placed in the second constant-diameter section until the fifth front punch moves to the bottom of the second constant-diameter section to form the fifth intermediate, the fifth rear punch is located below the second constant-diameter section, and the reduced-diameter section squeezes and contracts the second large-diameter section of the fourth intermediate.

2. The cold heading method according to claim 1, characterized in that The cold heading machine uses a third front punch, a third die body, and a third rear punch to perform a first punching on the second intermediate. The third rear punch is embedded in the third die body, and a third die cavity is formed between the third die body and the third rear punch. The third front punch is provided with a first-order rod for forming the first counterbore. The third die cavity includes a first small-diameter cavity wall for forming the first small-diameter section and a first large-diameter cavity wall for forming the first large-diameter section; The step of performing a first punching on the second intermediate obtained after shearing and positioning and grooving the upper and lower bottom surfaces to obtain the third intermediate includes: Drive the third forward punch rod to move, so as to cold press and form the second intermediate in the third die cavity and obtain the third intermediate; Drive the third backward punch rod to push out the third intermediate from the third die cavity.

3. The cold heading method according to claim 1, characterized in that The cold heading machine uses a fourth forward punch rod, a fourth die body and a fourth backward punch rod to perform secondary punching on the third intermediate. The fourth backward punch rod is embedded in the fourth die body, and a fourth die cavity is formed between the fourth die body and the fourth backward punch rod. The fourth forward punch rod has a second-order support rod for forming the second counterbore and the third counterbore. The fourth die cavity includes a second small-diameter cavity wall for forming the second small-diameter section and a second large-diameter cavity wall for forming the second large-diameter section; The step of performing secondary punching on the third intermediate through the cold heading machine to obtain the fourth intermediate includes: Drive the fourth forward punch rod to cold press and form the third intermediate in the fourth die cavity and obtain the fourth intermediate; Drive the fourth backward punch rod to push out the fourth intermediate from the fourth die cavity.

4. The cold heading method according to claim 1, characterized in that, The step of performing shape correction on the fifth intermediate through the cold heading machine to form the slender pipe fitting includes: Invert the fifth intermediate and perform straightening treatment with a cold heading machine to form a sixth intermediate, and the sixth intermediate includes a pipe fitting structure with an internal plug; Use the cold heading machine to punch out the plug to form the slender pipe fitting.

5. The cold heading method according to claim 4, characterized in that The cold heading machine uses a sixth forward punch rod, a sixth die body and a sixth backward punch rod to perform straightening treatment on the inverted fifth intermediate. The sixth die body and the sixth backward punch rod form a sixth die cavity. The sixth forward punch rod is provided with a second rod portion for forming the plug, and the sixth die cavity is used for forming the pipe fitting structure; The step of inverting the fifth intermediate and performing straightening treatment with a cold heading machine to form a sixth intermediate includes: Drive the sixth forward punch rod to cold press and form the fifth intermediate inverted in the sixth die cavity, and use the second rod portion to form the plug to form the sixth intermediate; Drive the sixth forward punch rod to push out the sixth intermediate from the sixth die cavity.

6. The cold heading method according to claim 4, characterized in that, The cold heading machine uses a seventh forward punch rod provided with a channel, a seventh die body, and a seventh backward punch rod to punch out the plug, and uses a support assembly coaxial with the seventh backward punch rod, a thimble disposed in a through hole of the support assembly, and a push rod assembly located above the support assembly to demold the slender pipe fitting. The seventh die body and the seventh backward punch rod form a seventh die cavity; The step of using the cold heading machine to punch out the plug to form the slender pipe fitting includes: Drive the seventh forward punch rod to move downward so that the plug is discharged from the channel; Drive the thimble to move so that the push rod assembly moves axially along the seventh backward punch rod to push out the slender pipe fitting.

7. The cold heading method according to any one of claims 1 to 6, characterized in that, Before the step of performing primary punching on the second intermediate obtained after shearing and positioning and grooving the upper and lower bottom surfaces to obtain the third intermediate, the method further includes: The target blank after being sheared by a cold heading machine is upset to form a first intermediate body. A first chamfer is provided on the first end face of the first intermediate body, and a first positioning groove is provided on the second end face of the first intermediate body. The first intermediate body is inverted, and the cold heading machine is used to perform grooving treatment on the first intermediate body to form a second intermediate body. The second intermediate body includes a second positioning groove provided on the first end face and a third positioning groove provided on the second end face. The second chamfer surrounds the second positioning groove.

8. The cold heading method according to claim 7, characterized in that The cold heading machine uses a first die body, a first front punch rod, and a first rear punch rod to perform upsetting treatment on the sheared target blank. The first die body and the first rear punch rod form a first die cavity. The bottom of the cavity wall of the first die cavity has a first conical surface for forming the first chamfer, and the pressing end of the first front punch rod of the die has a first convex platform for forming the first positioning groove. The step of performing upsetting treatment on the sheared target blank by the cold heading machine to form a first intermediate body includes: Driving the first front punch rod to push the sheared target blank placed in the first die cavity, and obtaining the first intermediate body through cold pressing forming. Driving the first rear punch rod to push the first intermediate body out of the first die cavity.

9. The cold heading method according to claim 8, wherein In the step of inverting the first intermediate body and using the cold heading machine to perform grooving treatment on the first intermediate body to form a second intermediate body, the cold heading machine uses a second die body, a second front punch rod, and a second rear punch rod to perform grooving treatment on the first intermediate body. The second die body and the second rear punch rod form a second die cavity. The pressing end of the second front punch rod is provided with a second convex platform for forming the second positioning groove and the second chamfer, and the bottom of the cavity wall of the second die cavity is provided with a second conical surface for forming the third positioning groove. The process of performing upsetting treatment on the sheared target blank by the cold heading machine to form a first intermediate body includes: Driving the second front punch rod to push the first intermediate body placed in the second die cavity, and forming the second intermediate body through cold pressing forming. Driving the second rear punch rod to push the second intermediate body out of the second die cavity.

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