Cold heading method

Abstract

The invention discloses a cold heading method which comprises the following steps: performing primary punching on a second intermediate obtained by shearing and positioning and slotting the upper and lower bottom surfaces to obtain a third intermediate, performing secondary punching on the third intermediate through a cold heading machine to obtain a fourth intermediate, and performing secondary punching on the fourth intermediate to obtain a fifth intermediate. And the fourth intermediate is subjected to equal-diameter stretching through the cold header to obtain a fifth intermediate, the fifth intermediate is subjected to shape correction through the cold header, and the slender pipe fitting is formed. According to the method, the blank is subjected to primary punching and secondary punching, the shaft-shaped intermediate with the two outer diameter sizes and the counter bores in the bottom is obtained, the intermediate subjected to secondary punching is subjected to equal-diameter stretching through the counter bores and then is corrected, an existing upsetting process is changed, and preparation of the long and thin pipe fitting is achieved.

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 comprises a rod-shaped structure, and a sizing countersink formed in the rod-shaped structure and composed of the third countersink and the second countersink with a reduced diameter;

[0010] The fifth intermediate is subjected to shape correction by the cold heading machine to form the elongated tube.

[0011] Punching the second intermediate body obtained after shearing and positioning and slotting the upper and lower bottom surfaces 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;

[0012] 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;

[0013] The fourth intermediate is subjected to equal diameter stretching by the cold heading machine to obtain a fifth intermediate, wherein the fifth intermediate comprises a rod-shaped structure, and a sizing countersink formed in the rod-shaped structure and composed of the third countersink and the second countersink with a reduced diameter;

[0014] The fifth intermediate is subjected to shape correction by the cold heading machine to form the elongated tube.

[0015] One possible way is that the cold heading machine uses a third front punch, a third die body, and a third rear punch to punch the second intermediate body once, the third rear punch is embedded in the third die body, 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 support rod for forming the first countersunk hole, and the third die cavity includes a first small-diameter cavity wall for forming the first small-diameter segment and a first large-diameter cavity wall for forming the first large-diameter segment;

[0016] The step of punching the second intermediate obtained after shearing and positioning and slotting the upper and lower bottom surfaces to obtain the third intermediate comprises:

[0017] driving the third front punch to move, so as to cold-press the second intermediate in the third mold cavity and obtain the third intermediate;

[0018] The third back punch is driven to push the third intermediate body out of the third mold cavity.

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

[0020] The step of subjecting the third intermediate to secondary punching through the cold heading machine to obtain the fourth intermediate comprises:

[0021] driving the fourth front punch to cold-press the third intermediate in the fourth die cavity to obtain the fourth intermediate;

[0022] The fourth back punch is driven to push the fourth intermediate body out of the fourth mold cavity.

[0023] One possible way is that the cold heading machine uses a fifth front punch, a fifth die body and a fifth rear punch to perform isodiametric stretching on the fourth intermediate body, the fifth front punch has a first support rod portion for forming the sizing countersunk hole, and the fifth die cavity includes a first constant diameter section, a second constant diameter section having a radial dimension not less than 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 subjecting the fourth intermediate to isodiametric stretching through the cold heading machine using the third countersunk hole to obtain the fifth intermediate comprises:

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

[0026] driving the fifth forward plunger to push the fourth intermediate body disposed in the second constant diameter section to form the fifth intermediate body;

[0027] driving the fifth back punch to move so as to push the fifth intermediate body out of the fifth die cavity;

[0028] The fifth front punch is driven to push the fourth intermediate body placed in the second constant diameter section until the fifth front punch moves to the bottom of the second constant diameter section. During the process of forming the fifth intermediate body, 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 body.

[0029] In one possible manner, the step of correcting the shape of the fifth intermediate by the cold heading machine to form the elongated tube comprises:

[0030] Inverting the fifth intermediate and performing a correction process using a cold heading machine to form a sixth intermediate, wherein the sixth intermediate includes a pipe structure with an inner plug;

[0031] The cold heading machine is used to punch out the plugging to form the elongated tube.

[0032] One possible way is that the cold heading machine uses a sixth front punch, a sixth die body and a sixth rear punch to perform a correction process on the inverted fifth intermediate, the sixth die body and the sixth rear punch form a sixth die cavity, the sixth front punch is provided with a second support rod portion for forming the plugging, and the sixth die cavity is used to form the pipe structure;

[0033] The step of inverting the fifth intermediate and performing a correction process with a cold heading machine to form a sixth intermediate comprises:

[0034] driving the sixth front punch to invert the fifth intermediate body in the sixth die cavity for cold press forming, and using the second support rod portion to form the plugging to form the sixth intermediate body;

[0035] The sixth forward punch is driven to push the sixth intermediate body out of the sixth mold cavity.

[0036] One possible way is that the cold heading machine uses a seventh front punch provided with a channel, a seventh die body, and a seventh rear punch to punch out the blockage, and uses a support assembly coaxial with the seventh rear punch, an ejector pin provided in a through hole of the support assembly, and a push rod assembly located above the support assembly to demould the elongated tube, and the seventh die body and the seventh rear punch form a seventh die cavity;

[0037] The step of using the cold heading machine to punch out the plugging to form the elongated tube comprises:

[0038] driving the seventh forward plunger to move downward to allow the blockage to be ejected from the passage;

[0039] The ejector pin is driven to move so that the push rod assembly moves axially along the seventh rear punch to push out the elongated tube.

[0040] One possible way is that before the step of punching the second intermediate obtained by passing the sheared columnar blank through a cold heading machine to obtain the third intermediate, the method further comprises:

[0041] The target blank sheared by the cold heading machine is subjected to upsetting treatment to form a first intermediate body, wherein a first end surface of the first intermediate body is provided with a first chamfer, and a second end surface of the first intermediate body is provided with a first positioning groove;

[0042] The first intermediate body is inverted, and a cold heading machine is used to perform a groove processing on the first intermediate body to form a second intermediate body, wherein the second intermediate body includes a second positioning groove arranged on the first end surface and a third positioning groove arranged on the second end surface, and the second positioning groove is surrounded by a second chamfer.

[0043] One possible way is that the cold heading machine uses a first die body, a first front punch and a first rear punch to perform a roughening process on the target blank after shearing, the first die body and the first rear punch 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 top pressing end of the first die front punch has a first boss for forming the first positioning groove;

[0044] The step of roughening and grooving the target blank after shearing by the cold heading machine to form a first intermediate comprises:

[0045] driving the first front punch to push the target blank placed in the first die cavity after shearing, and obtaining the first intermediate by cold pressing;

[0046] The first back punch is driven to push the first intermediate body out of the first mold cavity.

[0047] One possible way is that in the step of inverting the first intermediate body and performing a slotting process on the first intermediate body by using a cold heading machine to form a second intermediate body, the cold heading machine uses a second die body, a second front punch and a second rear punch to perform a slotting process on the first intermediate body, the second die body and the second rear punch form a second die cavity, the pressing end of the second front punch is provided with a second boss for forming a 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 roughening and grooving the target blank after shearing by the cold heading machine to form a first intermediate includes:

[0049] driving the second front punch to push the first intermediate body placed in the second mold cavity to form the second intermediate body by cold pressing;

[0050] The second back punch is driven to push the second intermediate body out of the second mold cavity.

[0051] The present application performs primary punching and secondary punching on the blank in sequence to obtain an axial intermediate having two outer diameters and a countersunk hole at the bottom, and corrects the intermediate after the secondary punching by equal-diameter stretching using the countersunk hole, thereby changing the existing upsetting process and realizing the preparation of slender pipe fittings. BRIEF 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 accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0053] Figure 1 A flow chart of a cold heading method provided by an embodiment of the present invention;

[0054] FIG2( a) is a cross-sectional view of a third intermediate of an embodiment of the present invention;

[0055] FIG2( b ) shows a cross-sectional view of a cold heading machine for preparing the third intermediate shown in FIG2( a );

[0056] FIG3( a) is a cross-sectional view of a fourth intermediate of an embodiment of the present invention;

[0057] FIG3( b ) shows a cross-sectional view of a cold heading machine for preparing the fourth intermediate body shown in FIG3( a );

[0058] FIG4( a) is a cross-sectional view of a fifth intermediate body according to an embodiment of the present invention;

[0059] FIG4( b ) shows a cross-sectional view of a cold heading machine for preparing the fifth intermediate body shown in FIG4( a );

[0060] FIG5( a) is a cross-sectional view of a sixth intermediate of an embodiment of the present invention;

[0061] FIG5( b ) shows a cross-sectional view of a cold heading machine for preparing the sixth intermediate body shown in FIG5( a );

[0062] FIG6( a) is a cross-sectional view of an elongated tube according to an embodiment of the present invention;

[0063] FIG6( b ) shows a cross-sectional view of a cold heading machine for preparing the elongated tube shown in FIG6( a );

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

[0065] Figure 8 A flow chart of another cold heading method shown in the present invention;

[0066] FIG9( a) is a cross-sectional view of a target blank after shearing according to an embodiment of the present invention;

[0067] FIG9( b ) shows a cross-sectional view of a cold heading machine for preparing the sheared target blank shown in FIG9( a );

[0068] FIG10( a) is a cross-sectional view of a first intermediate body according to an embodiment of the present invention;

[0069] FIG10( b ) shows a cross-sectional view of a cold heading machine for preparing the first intermediate body shown in FIG10( a );

[0070] FIG11( a) is a cross-sectional view of a second intermediate body according to an embodiment of the present invention;

[0071] FIG11( b ) shows a cross-sectional view of a cold heading machine for preparing the second intermediate body shown in FIG11( a );

[0072] Description of reference numerals:

[0073] 10. First intermediate body; 11. First positioning groove; 12. First chamfer; 13. First front punch; 14. First rear punch; 15. First die cavity; 16. First boss; 17. First cone; 18. First die body; 20. Second intermediate body; 21. Second positioning groove; 22. Second chamfer; 23. Third positioning groove; 24. Second front punch; 25. Second rear punch; 26. Second die body; 27. Second die cavity; 28. Second boss; 29. ​​Second cone ; 30, third intermediate body; 31, first countersunk hole; 32, first small diameter section; 33, first large diameter section; 34, third rear punch; 35, third mold body; 36, first-order support rod; 37, third mold cavity; 371, first large diameter cavity wall; 372, first small diameter cavity wall; 38, third front punch; 40, fourth intermediate body; 41, second small diameter section; 42, second countersunk hole; 43, second large diameter section; 44, third countersunk hole; 45, fourth front punch; 46, second-order support rod; 4 7. Fourth mold body; 48. Fourth mold cavity; 481. Second large diameter cavity wall; 482. Second small diameter cavity wall; 49. Fourth rear punch; 50. Fifth intermediate body; 51. Rod-shaped structure; 52. Sizing countersunk hole; 53. Fifth front punch; 54. First support rod; 55. Fifth mold cavity; 551. First constant diameter section; 552. Reduced diameter section; 553. Second constant diameter section; 56. Fifth mold body; 57. Fifth rear punch; 60. Sixth intermediate body; 61. Pipe fitting structure; 6 2. Blocking; 63. Sixth front punch; 64. Second support rod; 65. Sixth mold body; 66. Sixth mold cavity; 67. Sixth rear punch; 70. Slender pipe; 71. Seventh front punch; 71a. Channel; 72. Seventh rear punch; 73. Seventh mold body; 74a. First cushion block; 74b. Second cushion block; 74. Support assembly; 75. Ejector pin; 76. Through hole; 77a. Three-hole middle plate; 77b. Single-hole middle plate; 77. Push rod assembly; 78. Seventh mold cavity. DETAILED DESCRIPTION

[0074] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0075] 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:

[0076] When the length of the pipe increases, if the traditional method of upsetting from the top of the billet downward is used to prepare the slender pipe, the front punch needs to move from the top of the billet to the bottom. This upsetting method is difficult to ensure the coaxiality of the slender pipe. At the same time, the front punch is prone to breakage during the downward movement of the front punch, which hinders the preparation process.

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

[0078] S102: Punching the second intermediate obtained after shearing and positioning and slotting the upper and lower bottom surfaces to obtain a third intermediate.

[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 pipes with different radii. Combined with Figure 2(a), it can be seen that the radius of the upper pipe of the third intermediate body 30 is greater than the radius of the lower pipe, and the upper pipe of the third intermediate body 30 is provided with a countersunk hole (i.e., the first countersunk hole 31).

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

[0082] S104: The third intermediate is subjected to secondary punching by a cold heading machine to obtain a fourth intermediate.

[0083] Referring to FIG. 3(a), specifically, in this step, the fourth intermediate body 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 body 30 shown in FIG. 2(a). The second small diameter section 41 is formed by extending the first small diameter section 32 of the third intermediate body 30 shown in FIG. 2(a). In addition, the fourth intermediate body 40 also includes a second countersunk hole 42 and a third countersunk hole 44, the second countersunk hole 42 is formed by extending the first countersunk hole 31 shown in FIG. 2(a), and the second countersunk hole 42 is formed in the second large diameter section 43 and is connected to the third countersunk hole 44. The third countersunk hole 44 is formed in the second small diameter section 41. Referring to FIG. 3(a), it can be seen that the diameter of the third countersunk hole 44 is smaller than the diameter of the second countersunk hole 42.

[0084] In the present application, no specific limitation is made on 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 by a cold heading machine using the third countersunk hole to obtain a fifth intermediate.

[0086] In the present application, referring to FIG. 4( a ), the fifth intermediate body 50 includes a rod-like structure 51 and a sizing countersunk hole 52 . The sizing countersunk hole 52 is formed in the rod-like structure 51 and is composed of the third countersunk hole 44 in FIG. 3( a ) and the second countersunk hole 42 with a reduced diameter.

[0087] In combination with the above, the fourth intermediate body 40 includes a second countersunk hole 42 and a third countersunk hole 44. When pressure is applied to the third countersunk hole 44 of the fourth intermediate body 40, the third intermediate body 30 is longitudinally stretched, and the size of the second countersunk hole 42 and the second large diameter section gradually decreases, and finally a rod-shaped structure 51 with a countersunk hole at the bottom is obtained. Referring to FIG. 4(a), each cross section of the rod-shaped structure 51 has the same outer diameter and inner diameter.

[0088] S108: The fifth intermediate is subjected to shape correction by a cold heading machine to form a slender pipe.

[0089] Based on the foregoing, it can be known that the elongated tube can be prepared by correcting the shape of the fifth intermediate.

[0090] The present application obtains an axial intermediate having two outer diameters and a countersunk hole at the bottom by punching the blank once and twice, and corrects the intermediate after the secondary punching by equal-diameter stretching using the countersunk hole, thereby changing the existing upsetting process and realizing the preparation of slender pipe fittings.

[0091] The following will specifically describe the steps S102 to S108:

[0092] In step S102: punching the second intermediate body 20 obtained after shearing and positioning grooving to obtain the third intermediate body 30, it can be seen from Figure 2(a) and Figure 2(b) that the cold heading machine uses a third front punch rod 38, a third mold body 35, and a third rear punch rod 34 to punch the second intermediate body 20 once, and a first-order support rod 36 is provided at the bottom of the third front punch rod 38, and the first-order support rod 36 is used to form the first countersunk hole 31.

[0093] The third back punch 34 is embedded in the third mold body 35, and a third mold cavity 37 is formed between the third mold body 35 and the third back punch 34. In order to form the first large diameter section 33 and the first small diameter section 32, the third mold 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, the third front punch 38 is first driven to move so that the second intermediate body 20 in the third die cavity 37 is deformed. At this time, under the action of the third die body 35, the second intermediate body 20 in the third die cavity 37 is squeezed and deformed. Specifically, the third front punch 38 moves downward to form the first counterbore 31. The blank outside the first counterbore 31 diffuses radially to form the aforementioned third intermediate body 30.

[0095] At this time, the third intermediate body 30 is still in the third mold cavity 37. In order to separate the third intermediate body 30 from the third mold cavity 37, the third back punch 34 is driven upward to push the third intermediate body 30 out of the third mold cavity 37, thereby completing a punching process.

[0096] It should be noted that the above-mentioned single punching step is only one feasible method provided in the present application. Those skilled in the art may refer to other methods to punch the blank once, which are also included in the protection scope of the present application.

[0097] Continuing with reference to FIG. 2( b ), in order to achieve positioning of the blank, in some other embodiments, a boss is provided at the bottom of the third front punch 38 for matching with the positioning groove located on the upper surface of the second intermediate body 20, and a boss is provided at the top of the third rear punch 34 for matching with the positioning groove located on the lower surface of the second intermediate body 20. By utilizing the matching of the boss and the positioning groove, the positioning of the second intermediate body 20 can be achieved, thereby improving the accuracy of cold pressing.

[0098] In step S104: performing secondary punching on the third intermediate 30 by a cold heading machine to obtain a fourth intermediate 40, in some embodiments, in combination with Figure 2(b) and 3(b)It can be seen that the cold heading machine uses the fourth front punch 45 , the fourth die body 47 and the fourth rear punch 49 to perform secondary punching on the third intermediate body 30 .

[0099] Combining FIG. 3( b ), it can be seen that the fourth rear punch 49 is embedded in the fourth mold body 47, and a fourth mold cavity 48 is formed between the fourth mold body 47 and the fourth rear punch 49. The fourth front punch 45 has a second-stage support rod 46, and the second-stage support rod 46 is specifically used to form the second counterbore 42 and the third counterbore 44. The fourth mold cavity 48 includes a second small-diameter cavity wall 482 and a second large-diameter cavity wall 481, and the second small-diameter cavity wall 482 is used to form the second small-diameter section 41, and the second large-diameter cavity wall 481 is used to form the second large-diameter section 43.

[0100] In this step, first, the fourth front punch 45 is driven to cold-press the third intermediate body 30 in the fourth mold cavity 48 to obtain the fourth intermediate body 40 .

[0101] When the fourth front punch 45 moves downward, under the action of the second-stage support rod 46, the fourth mold cavity 48 extends the first counterbore 31 of the third intermediate body 30 shown in FIG. 3(a) to form a second counterbore 42, and the third intermediate body 30 forms a third counterbore 44 under the action of the second-stage support rod 46. Under the action of the fourth front punch 45 moving downward, the third intermediate body 30 of the fourth mold cavity 48 forms a second large diameter section 43 and a second small diameter section 41 along the radial outer edge, respectively, under the action of the second small diameter cavity wall 482 and the second large diameter cavity wall 481, thereby obtaining the fourth intermediate body 40.

[0102] After the fourth intermediate body 40 is formed, the fourth intermediate body 40 is still in the fourth mold cavity 48 . In order to demold the fourth intermediate body 40 , the sixth front punch 63 is driven to push the sixth intermediate body out of the sixth mold cavity 66 .

[0103] On the basis of the aforementioned embodiment, referring to FIG. 3( b ), after slotting, positioning grooves are provided on the upper and lower bottom surfaces of the second intermediate body 20 , and the presence of the positioning grooves is not affected in the aforementioned single punching step. It can be seen that positioning grooves are provided on the upper and lower bottom surfaces of the third intermediate body 30 .

[0104] Based on this, in some further embodiments, a boss that cooperates with the positioning groove located on the upper surface of the third intermediate body 30 is provided on the fourth front punch 45, and a boss that cooperates with the positioning groove located on the lower surface of the third intermediate body 30 is provided on the fourth rear punch 49. By utilizing the cooperation of the boss and the positioning groove, the third intermediate body 30 can be positioned, thereby improving the accuracy of cold pressing.

[0105] In step S106: using the third countersunk hole to perform isodiametric stretching on the fourth intermediate body through a cold heading machine to obtain a fifth intermediate body 50, referring to Figures 4(a) and 4(b), in some embodiments, the cold heading machine uses a fifth front punch 53, a fifth mold body 56 and a fifth rear punch 57 to perform isodiametric stretching on the fourth intermediate body 40.

[0106] The fifth front punch 53 has a first support rod portion 54, and the first support rod portion 54 is specifically used to form the sizing countersunk hole 52. The fifth mold cavity 55 includes a first constant diameter section 551, a second constant diameter section 553 and a reduced diameter section 552, and 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 the radial dimension of the first constant diameter section 551.

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

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

[0109] It is worth noting that, during this process, the fifth rear 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 mold cavity 55 , and the fifth back punch 57 is driven to move upward to push the fifth intermediate body 50 out of the fifth mold cavity 55 , thereby achieving demolding of the fifth intermediate body 50 .

[0111] Based on the above, referring to Figure 4(b), after positioning grooves are formed, positioning grooves can be provided on the upper and lower surfaces of the second intermediate body 20. Combined with the above steps, positioning grooves are provided on the upper and lower surfaces of the fifth intermediate body 50, provided that the first punching and the second punching do not affect the existence of the positioning grooves.

[0112] Based on this, in some further embodiments, a boss that cooperates with the positioning groove located on the upper surface of the fourth intermediate body 40 is provided on the fifth front punch 53, and a boss that cooperates with the positioning groove located on the lower surface of the fourth intermediate body 40 is provided on the fifth rear punch 57. By utilizing the cooperation of the boss and the positioning groove, the fourth intermediate body 40 can be positioned, thereby improving the accuracy of cold pressing.

[0113] In this way, it is not necessary to prepare a slender front punch rod when preparing a slender tube, and it is easy to ensure the coaxiality of the slender tube, and the front punch rod is not easy to break during the cold pressing process.

[0114] In step S108: correcting the shape of the fifth intermediate by a cold heading machine to form a slender tube, in order to improve the coaxiality of the slender tube, refer to Figure 4(a) , 5(a) 5(b), firstly, S108a is performed: the fifth intermediate body 50 is inverted, and the sizing counterbore 52 at the bottom of the fifth intermediate body 50 is flipped to the top of the fifth intermediate body 50, and then a cold heading machine is used to perform a correction process to form a sixth intermediate body 60. Specifically, the sixth intermediate body 60 includes a pipe structure 61 having an inner plug 62.

[0115] Through this step, the sixth intermediate body 60 obtained above is reshaped again, thereby improving the coaxiality of the slender tube.

[0116] After the sixth intermediate 60 is obtained, S108b is executed: the plug is punched out by a cold heading machine to form a slender pipe.

[0117] Through this step, the waste of the elongated sixth intermediate body 60 is discharged, thereby achieving the preparation of the elongated tube.

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

[0119] In this step, first, the sixth front punch 63 is driven to invert the fifth intermediate 50 in the sixth mold cavity 66 for cold pressing, and under the extrusion of the sixth front punch 63, the second support rod 64 is used to form a plug 62 to form the sixth intermediate 60. At this time, the sixth intermediate 60 is still in the sixth mold cavity 66, and the sixth front punch 63 is driven to push the sixth intermediate shown in Figure 5 (a) out of the sixth mold cavity 66, so that the sixth intermediate 60 can be obtained.

[0120] By means of the above method, the fifth intermediate body 50 can be further corrected, thereby improving the coaxiality of the slender tube.

[0121] 5(a) and 6(b), in S108b: using a cold heading machine to punch out the seal to form a slender tube, firstly, the sixth intermediate is placed in the seventh mold body 73, and the cold heading machine uses the seventh front punch rod 71 to punch out the seal 62. Specifically, the seventh front punch rod is provided with a channel 71a. When the seventh front punch rod 71 moves downward, the channel 71 discharges excess waste to obtain the slender tube shown in FIG6(a). The slender tube shown in 6(a) is separated from the seventh mold cavity 78 to obtain the slender tube shown in 6(a).

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

[0123] In some embodiments, the head of the back punch is relatively high. In this case, if the back punch is used alone to push out the slender tube, the slender tube will easily fit around the rod head, making it impossible to separate the slender tube from the rod head.

[0124] To solve this problem, the cold heading machine uses a support assembly, an ejector pin, and a push rod assembly to demould the slender pipe.

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

[0126] After the seventh front punch pushes out the seal 62, the screw is used to drive the aforementioned ejector pin 75 to move in the channel, thereby driving the push rod assembly 77 to push the slender tube in Figure 6 (a) to move, and the slender tube is separated from the head of the seventh rear punch, thereby realizing demoulding when the head of the rear punch is relatively high.

[0127] As shown in FIG6(b), illustratively, the support assembly 74 includes a first cushion block 74a and a second cushion block 74b, wherein the first cushion block 74a is located below the seventh mold 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 mold body 73, and the push rod assembly includes a three-hole middle piece 77a and a single-hole middle piece 77b, wherein 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 of FIG6(a).

[0128] When the ejector moves, the three-hole middle piece and the single-hole middle piece are driven to move, thereby demoulding the slender rod.

[0129] It can be seen that in this embodiment, in the step S108b of using a cold heading machine to punch out the seal to form a slender tube, first, the seventh front punch is driven to move downward to allow the seal 62 shown in Figure 5(a) to be discharged from the channel, and then the ejector pin is driven to move so that the push rod assembly moves axially along the seventh rear punch to push out the slender tube.

[0130] Through the above implementation, demoulding can be achieved when the height of the back punch head is relatively high.

[0131] Reference Figure 7 as well as Figure 8 Another cold heading method provided in the embodiment of the present application specifically comprises the following steps:

[0132] S202: The target blank sheared by the cold heading machine is subjected to a roughening treatment to form a first intermediate.

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

[0134] In order to obtain the first intermediate body 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 FIG10(b), the cold heading machine uses the first die body 18, the first front punch 13 and the first rear punch 14 to perform a roughening process on the target blank after shearing. The first die body 18 and the first rear 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, the first front punch 13 is driven to push the target blank after shearing placed in the first die cavity 15, and the first intermediate is obtained by cold pressing. At this time, the first intermediate is formed under the action of the first front punch 13 and the first die cavity 15. Finally, the first back punch 14 is driven 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 body, and use a cold heading machine to perform a groove process on the second end surface of the first intermediate body to form a second intermediate body.

[0138] Specifically, referring to FIG. 11( a ), the second intermediate body 20 includes a second positioning groove 21 disposed on the first end surface and a third positioning groove 23 disposed on the second end surface, and a second chamfer 22 is disposed 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 rear punch 25 to perform a groove process on the first intermediate body 10 of Figure 10 (a), and the second die body 26 and the first rear punch 14 form a second die cavity 27. The top pressing end of the second front punch 24 is provided with a second boss 28, and the second boss 28 is used to form the second positioning groove 21 and the second chamfer 22. The bottom of the cavity wall of the second die cavity 27 is provided with a second conical surface 29, and the second conical surface 29 is used to form a third positioning groove 23.

[0140] Specifically, in order to obtain the second positioning body 20, first, the second front punch 24 is driven to push the first intermediate body placed in the second mold cavity 27. At this time, under the action of the second front punch 24 and the second mold cavity 27, the second intermediate body 20 is formed by cold pressing. Then, the first rear punch 14 is driven to push the first intermediate body shown in Figure 10 (a) out of the second mold cavity 27.

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

[0142] S206: Punching the second intermediate obtained after shearing and positioning and slotting the upper and lower bottom surfaces to obtain a third intermediate.

[0143] S208: The third intermediate is subjected to secondary punching by a cold heading machine to obtain a fourth intermediate.

[0144] S210: The fourth intermediate 40 is subjected to equal-diameter stretching by a cold heading machine to obtain a fifth intermediate.

[0145] S212: The fifth intermediate body 50 is subjected to shape correction by a cold heading machine to form a slender tube.

[0146] Regarding steps S206 to S212, please refer to the aforementioned S102 to S108. The beneficial effects thereof may be specifically referred to S102 to S108, which will not be described in detail here.

[0147] On the basis of all the aforementioned embodiments, in the present application, all the dies can be made of alloy materials, that is, the first to seventh dies are all made of alloy materials, which can prevent the blank from wearing the die during the upsetting process.

[0148] This application has the following beneficial effects:

[0149] 1. The blank is punched once and twice to obtain an axial intermediate with two outer diameters and a countersunk hole at the bottom. The intermediate after the secondary punching is corrected by equal-diameter stretching using the countersunk hole. The preparation of slender pipe fittings is achieved by changing the existing upsetting process.

[0150] 2. Upsetting the blank and then slotting it, pre-treating the sheared blank can reduce the burrs of the sheared blank and improve the flatness of the blank.

[0151] 3. When demolding the slender tube, use the ejector pin to push the push rod assembly to prevent the slender tube from covering the rod head of the back punch during demolding.

[0152] In the above description of the present application, unless otherwise clearly specified and limited, the terms "fixed", "installed", "connected" or "connected" and the like should be understood in a broad sense. For example, with regard to the term "connection", 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 a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of 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 the specific circumstances.

[0153] According to the above description of the present application, those skilled in the art may also understand that the terms used below, such as "upper", "lower", "front", "back", "left", "right", "length", "width", "thickness", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", etc., which indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the drawings of the present application, and are only for the purpose of facilitating the explanation of the scheme of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the device or element involved must have the specific orientation, be constructed and operate in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms cannot be understood or interpreted as limitations on the scheme of the present invention.

[0154] In addition, the terms "first" or "second" used in this application to refer to numbers or ordinals are only used for descriptive purposes and cannot be understood as explicitly or implicitly indicating relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, the meaning of "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 may conceive of many changes, modifications, and alternatives without departing from the thought and spirit of the present invention. It should be understood that in the process of practicing the present invention, various alternatives to the embodiments of the present invention described herein may be adopted. The appended claims are intended to define the scope of protection of the present invention, and therefore 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 to prepare 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, and is characterized in that the steps include: Punching the second intermediate body obtained after shearing and positioning and slotting the upper and lower bottom surfaces 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; 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; The fourth intermediate is subjected to equal diameter stretching by the cold heading machine to obtain a fifth intermediate, wherein the fifth intermediate comprises a rod-shaped structure, and a sizing countersink formed in the rod-shaped structure and composed of the third countersink and the second countersink with a reduced diameter; The fifth intermediate is subjected to shape correction by the cold heading machine to form the elongated tube.

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 punch the second intermediate body once, the third rear punch is embedded in the third die body, 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 support rod for forming the first countersunk hole, and the third die cavity includes a first small-diameter cavity wall for forming the first small-diameter segment and a first large-diameter cavity wall for forming the first large-diameter segment; The step of punching the second intermediate obtained after shearing and positioning and slotting the upper and lower bottom surfaces to obtain the third intermediate comprises: driving the third front punch to move, so as to cold-press the second intermediate in the third mold cavity and obtain the third intermediate; The third back punch is driven to push the third intermediate body out of the third mold cavity.

3. The cold heading method according to claim 1, characterized in that: The cold heading machine uses a fourth front punch, a fourth die body and a fourth rear punch to perform secondary punching on the third intermediate body, the fourth rear punch is embedded in the fourth die body, a fourth die cavity is formed between the fourth die body and the fourth rear punch, the fourth front punch has a second-order support rod for forming the second countersunk hole and the third countersunk hole, and 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 subjecting the third intermediate to secondary punching through the cold heading machine to obtain the fourth intermediate comprises: driving the fourth front punch to cold-press the third intermediate in the fourth die cavity to obtain the fourth intermediate; The fourth back punch is driven to push the fourth intermediate body out of the fourth mold cavity.

4. The cold heading method according to claim 1, characterized in that: The cold heading machine uses a fifth front punch, a fifth die body and a fifth rear punch to perform isodiametric stretching on the fourth intermediate body, the fifth front punch has a first support rod portion for forming the sizing countersunk hole, and the fifth die cavity includes a first constant diameter section, a second constant diameter section having a radial dimension not less than 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 subjecting the fourth intermediate to isodiametric stretching through the cold heading machine using the third countersunk hole to obtain the fifth intermediate comprises: Driving the fifth front punch to move until it abuts against the third counterbore; driving the fifth forward plunger to push the fourth intermediate body disposed in the second constant diameter section to form the fifth intermediate body; driving the fifth back punch to move so as to push the fifth intermediate body out of the fifth die cavity; The fifth front punch is driven to push the fourth intermediate body placed in the second constant diameter section until the fifth front punch moves to the bottom of the second constant diameter section. During the process of forming the fifth intermediate body, 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 body.

5. The cold heading method according to claim 1, characterized in that: The step of correcting the shape of the fifth intermediate by the cold heading machine to form the elongated tube comprises: Inverting the fifth intermediate and performing a correction process using a cold heading machine to form a sixth intermediate, wherein the sixth intermediate includes a pipe structure with an inner plug; The cold heading machine is used to punch out the plugging to form the elongated tube.

6. The cold heading method according to claim 5, characterized in that: The cold heading machine uses a sixth front punch, a sixth die body and a sixth rear punch to perform a correction process on the inverted fifth intermediate body, the sixth die body and the sixth rear punch form a sixth die cavity, the sixth front punch is provided with a second support rod portion for forming the plugging, and the sixth die cavity is used to form the pipe structure; The step of inverting the fifth intermediate and performing a correction process with a cold heading machine to form a sixth intermediate comprises: driving the sixth front punch to invert the fifth intermediate body in the sixth die cavity for cold press forming, and using the second support rod portion to form the plugging to form the sixth intermediate body; The sixth forward punch is driven to push the sixth intermediate body out of the sixth mold cavity.

7. The cold heading method according to claim 5, characterized in that: The cold heading machine uses a seventh front punch provided with a channel, a seventh die body, and a seventh rear punch to punch out the blockage, and uses a support assembly coaxial with the seventh rear punch, an ejector pin provided in a through hole of the support assembly, and a push rod assembly located above the support assembly to demould the elongated tube, and the seventh die body and the seventh rear punch form a seventh die cavity; The step of using the cold heading machine to punch out the plugging to form the elongated tube comprises: driving the seventh forward plunger to move downward to allow the blockage to be ejected from the passage; The ejector pin is driven to move so that the push rod assembly moves axially along the seventh rear punch to push out the elongated tube.

8. The cold heading method according to any one of claims 1 to 7, characterized in that: Before the step of punching the second intermediate obtained by passing the sheared columnar blank through a cold heading machine to obtain a third intermediate, the method further comprises: The target blank sheared by the cold heading machine is subjected to upsetting treatment to form a first intermediate body, wherein a first end surface of the first intermediate body is provided with a first chamfer, and a second end surface of the first intermediate body is provided with a first positioning groove; The first intermediate body is inverted, and a cold heading machine is used to perform a groove processing on the first intermediate body to form a second intermediate body, wherein the second intermediate body includes a second positioning groove arranged on the first end surface and a third positioning groove arranged on the second end surface, and the second positioning groove is surrounded by a second chamfer.

9. The cold heading method according to claim 8, characterized in that: The cold heading machine uses a first die body, a first front punch and a first rear punch to perform a roughening process on the target blank after shearing, the first die body and the first rear punch 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 top pressing end of the first die front punch has a first boss for forming the first positioning groove; The step of roughening and grooving the target blank after shearing by the cold heading machine to form a first intermediate comprises: driving the first front punch to push the target blank placed in the first die cavity after shearing, and obtaining the first intermediate by cold pressing; The first back punch is driven to push the first intermediate body out of the first mold cavity.

10. The cold heading method according to claim 8, characterized in that: In the step of inverting the first intermediate body and performing a slotting process on the first intermediate body by using a cold heading machine to form a second intermediate body, the cold heading machine uses a second die body, a second front punch and a second rear punch to perform a slotting process on the first intermediate body, the second die body and the second rear punch form a second die cavity, the pressing end of the second front punch is provided with a second boss for forming a 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 roughening and grooving the target blank after shearing by the cold heading machine to form a first intermediate includes: driving the second front punch to push the first intermediate body placed in the second mold cavity to form the second intermediate body by cold pressing; The second back punch is driven to push the second intermediate body out of the second mold cavity.

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