Cold Heading Dies and Cold Heading Forming Processes

Abstract

The present invention relates to the technical field of bolt cold heading processing and forming, and in particular to a cold heading die and a cold heading forming process. The cold heading die includes a moving die sleeve, a static die sleeve, a punch assembly, and a waste material pushing-out assembly. A toothed machining hole is formed inside the static die sleeve, and a cutting edge is provided at an end of an edge of the toothed machining hole close to the moving die sleeve; the punch assembly is arranged in the moving die sleeve, and a part of the punch assembly within at least a predetermined distance is adapted to the toothed machining hole, and the moving die sleeve can move relative to the static die sleeve to drive the punch assembly to enter and exit the toothed machining hole; the waste material pushing-out assembly includes a connecting seat and a plurality of pushing pins connected to the connecting seat, and the connecting seat can move along the moving die sleeve so that the pushing pins can enter and exit the tooth gap. The cold heading forming process uses the cold heading die. The cold heading die and the cold heading forming process can timely push out the waste material after the toothed head is formed, making it possible to cold head form the toothed head and meeting the requirements for mass production of toothed heads.

Description

Technical Field

[0001] The present invention relates to the technical field of cold heading processing and forming of bolts, and particularly relates to a cold heading die and a cold heading forming process. Background Art

[0002] For bolts with a toothed head, due to the complex structure of the toothed head and high dimensional accuracy requirements, etc., in the related art, generally, the toothed head is processed by milling and precision extrusion methods, with low production efficiency, and both the processing equipment and die costs are relatively high, thus it is difficult to meet the requirements of mass-producing toothed heads. Summary of the Invention

[0003] The first object of the present invention is to provide a cold heading die to solve, to a certain extent, the technical problem that the prior art is difficult to meet the requirements of mass-producing toothed heads.

[0004] The second object of the present invention is to provide a cold heading forming process to solve, to a certain extent, the technical problem that the prior art is difficult to meet the requirements of mass-producing toothed heads.

[0005] To achieve the above objects, the present invention provides the following technical solutions;

[0006] Based on the above first object, the cold heading die provided by the present invention is used for processing bolts with a toothed head, and includes a moving die sleeve, a stationary die sleeve, a punch assembly, and a waste material pushing-out assembly;

[0007] A toothed machining hole is formed inside the stationary die sleeve, and a cutting edge is provided at an end of an edge of the toothed machining hole close to the moving die sleeve;

[0008] The punch assembly is arranged in the moving die sleeve, the punch assembly protrudes from the moving die sleeve towards the toothed machining hole by a predetermined distance, the predetermined distance is not less than the target thickness of the toothed head, and at least a part of the punch assembly within the predetermined distance is adapted to the toothed machining hole;

[0009] The moving die sleeve can move relative to the stationary die sleeve to drive the punch assembly in and out of the toothed machining hole;

[0010] The waste material pushing-out assembly includes a connecting seat and a plurality of push pins connected to the connecting seat, and the plurality of push pins correspond one by one to a plurality of tooth gaps on the outer side wall of the punch assembly;

[0011] The connecting seat is movably connected to the moving die sleeve, and the connecting seat can move along the moving die sleeve so that the push pins can move in and out of the tooth gaps.

[0012] In any of the above technical solutions, optionally, the punch assembly includes a separator and a punch body;

[0013] A first mounting through hole is provided inside the movable die sleeve, and the waste ejection assembly and the separator are sequentially arranged on the punch body in the first mounting through hole, the punch body is located on a side of the separator close to the static die sleeve, and the connecting seat is located on a side of the separator away from the static die sleeve;

[0014] The separator is fixedly mounted in the first mounting through hole, one end of the punch body extends into the first mounting through hole and is connected to the separator, and the other end of the punch body extends out of the first mounting through hole by a predetermined distance, and the outer surface of the punch body is adapted to the inner surface of the tooth-shaped processing hole;

[0015] The separator is provided with communication holes corresponding to the gaps between the teeth, and the communication holes connect the two sides of the separator;

[0016] The plurality of push pins pass through the plurality of connecting holes and extend into the inter-tooth gaps in a one-to-one correspondence. The connecting seat is movably disposed in the first mounting through hole to drive the push pins to move in the inter-tooth gaps.

[0017] In any of the above technical solutions, optionally, the connecting seat includes a sliding seat body and a push-pull handle;

[0018] The plurality of push pins are connected to one end of the slide body facing the partition seat, one end of the push-pull handle is connected to one end of the slide body facing away from the partition seat, and the other end of the push-pull handle extends out of the first mounting through hole.

[0019] In any of the above technical solutions, optionally, the length of the push pin is not less than the sum of the lengths of the punch body and the partition seat.

[0020] In any of the above technical solutions, optionally, the cutting edge forms a predetermined angle with the axis of the tooth-shaped processing hole, and the end of the cutting edge close to the movable mold sleeve is farther from the axis of the tooth-shaped processing hole than the end of the cutting edge away from the movable mold sleeve.

[0021] In any of the above technical solutions, optionally, the predetermined angle is 60-80°;

[0022] And / or, the projection distance of the cutting edge on the axis of the static die sleeve is not less than 1 mm.

[0023] In any of the above technical solutions, optionally, the cold heading die further includes a forming portion and a support sleeve;

[0024] A second mounting through hole is formed inside the static mold sleeve, and the forming portion is arranged in the second mounting through hole;

[0025] A positioning hole is formed inside the support sleeve to match the circumferential side wall of the bolt to be upset;

[0026] The tooth-shaped processing hole is formed inside the forming portion, at least a portion of the outer surface of the support sleeve is adapted to the tooth-shaped processing hole, and the support sleeve can at least move the predetermined distance along the tooth-shaped processing hole.

[0027] In any of the above technical solutions, optionally, the cold heading die further includes a limiting portion and an elastic reset mechanism;

[0028] The limiting portion is arranged in the second mounting through hole and is located on a side of the forming portion away from the movable mold sleeve;

[0029] The support sleeve includes a support portion and a stop portion, the support portion is adapted to the tooth-shaped processing hole, the stop portion is connected to an end of the support portion away from the movable mold sleeve, the stop portion is located between the forming portion and the limiting portion and can abut against the forming portion;

[0030] The elastic restoring mechanism is supported between the limiting portion and the stopping portion, and applies an elastic restoring force toward the forming portion to the stopping portion.

[0031] In any of the above technical solutions, optionally, the cold heading die further includes a material taking push rod;

[0032] The positioning hole passes through the supporting portion and the stopping portion;

[0033] The limiting portion is provided with a through hole communicating with the positioning hole, one end of the material taking push rod passes through the through hole and extends into the positioning hole, and the other end of the material taking push rod extends out of the second mounting through hole;

[0034] And / or, the end surface of the static die sleeve facing the dynamic die sleeve is coated with a hard alloy wear-resistant coating.

[0035] Based on the above second object, the present invention provides a cold heading process for processing a bolt with a toothed head, and the cold heading process specifically comprises the following steps:

[0036] cutting the wire blank to form a first stepped blank, wherein the cross-sectional area of the first stepped blank is larger than the cross-sectional area of the toothed head bolt;

[0037] Pre-shrinking the screw portion of the first step-shaped billet to obtain a second step-shaped billet, wherein the cross-sectional area of the second step-shaped billet is reduced by 20-30% compared with the cross-sectional area of the first step-shaped billet;

[0038] Perform a primary upsetting on the second stepped blank to obtain a third stepped blank, and the head height of the second stepped blank is reduced compared to the height of the second stepped blank;

[0039] Perform a secondary upsetting on the height of the third stepped blank to obtain a fourth stepped blank. The head height of the third stepped blank is 1.5 - 1.8 times the head height of the fourth stepped blank, and the head diameter of the third stepped blank is 0.75 - 0.8 times the head diameter of the fourth stepped blank;

[0040] Perform chamfer upsetting and blank diameter upsetting on the screw part of the fourth stepped blank to obtain the to - be - upset - tooth bolt;

[0041] Use the cold - heading die described in any of the above - mentioned technical solutions to perform tooth forming on the head of the to - be - upset - tooth bolt.

[0042] Adopting the above - mentioned technical solution, the beneficial effects of the present invention are:

[0043] The cold - heading die provided by the present invention includes a moving die sleeve, a static die sleeve, a punch assembly, and a waste - material pushing - out assembly. A tooth - shaped processing hole is formed inside the static die sleeve, and a cutting edge is provided at the end of the edge of the tooth - shaped processing hole close to the moving die sleeve. Thus, when the to - be - upset - tooth bolt is pressed into the tooth - shaped processing hole, the cutting edge can cut the head of the to - be - upset - tooth bolt at the position corresponding to the edge of the tooth - shaped processing hole. After the cutting edge cuts along the entire length direction of the head of the to - be - upset - tooth bolt, a bolt with a tooth - shaped head squeezed into the tooth - shaped processing hole can be obtained. The punch assembly is arranged in the moving die sleeve, and the punch assembly protrudes from the moving die sleeve towards the tooth - shaped processing hole by a predetermined distance. The predetermined distance is not less than the target thickness of the tooth - shaped head, and at least the part within the predetermined distance of the punch assembly is adapted to the tooth - shaped processing hole. The moving die sleeve can move relative to the static die sleeve to drive the punch assembly in and out of the tooth - shaped processing hole, so that the cutting edge can continuously cut the head of the bolt through the extrusion action of the punch assembly on the to - be - upset - tooth bolt. The waste - material pushing - out assembly includes a connecting seat and a plurality of push pins connected to the connecting seat. The plurality of push pins correspond one - to - one to the plurality of tooth - space gaps on the outer sidewall of the punch assembly. The connecting seat is movably connected to the moving die sleeve, and the connecting seat can move along the moving die sleeve to enable the push pins to move in and out of the tooth - space gaps. As the punch assembly enters the tooth - shaped processing hole, the tooth - shaped processing hole can squeeze the waste material into the tooth - space gaps of the punch assembly. After the tooth - shaped head is formed, the waste material can be pushed out from the tooth - space gaps through the waste - material pushing - out assembly, so that the punch assembly can cooperate with other components of the cold - heading die to perform the next tooth - shaped head forming operation. Since this cold - heading die can discharge waste while forming the tooth - shaped head and can timely push out the waste from the cold - heading die after the tooth - shaped head is formed, it makes the cold - heading forming of the tooth - shaped head possible, and thus can meet the requirements of mass - producing tooth - shaped heads.

[0044] The cold heading forming process provided by the present invention adopts the above-mentioned cold heading die, and thus can achieve all the beneficial effects of the above-mentioned cold heading die. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0046] Figure 1 Structural schematic diagram of the cold heading die provided in the first embodiment of the present invention in the working state;

[0047] Figure 2 Structural schematic diagram of the moving die sleeve of the cold heading die provided in the first embodiment of the present invention and other internal parts;

[0048] Figure 3 Structural schematic diagram of the moving die sleeve of the cold heading die provided in the first embodiment of the present invention;

[0049] Figure 4 For Figure 3 right view;

[0050] Figure 5 Structural schematic diagram of the punch body of the cold heading die provided in the first embodiment of the present invention;

[0051] Figure 6 For Figure 5 right view;

[0052] Figure 7 Structural schematic diagram of the forming part of the cold heading die provided in the first embodiment of the present invention;

[0053] Figure 8 For Figure 7 cross-sectional view taken along the A-A section;

[0054] Figure 9 Structural schematic diagram of the support sleeve of the cold heading die provided in the first embodiment of the present invention;

[0055] Figure 10 Change process of the bolt structure formed by the cold heading forming process provided in the second embodiment of the present invention;

[0056] Figure 11 For Figure 10 top view;

[0057] Figure 12 Structural schematic diagram of the linear blank used in the cold heading forming process provided in the second embodiment of the present invention.

[0058] Icon: 1 - static die sleeve; 10 - second guide sleeve; 2 - moving die sleeve; 20 - first guide sleeve; 21 - first mounting through hole; 3 - punch assembly; 30 - punch body; 31 - tooth gap; 32 - separating seat; 33 - connecting threaded hole; 4 - waste pushing-out assembly; 40 - ejector pin; 41 - slide body; 42 - push-pull handle; 5 - forming part; 50 - tooth-shaped machining hole; 51 - cutting edge; 52 - predetermined angle; 53 - projection distance; 6 - support sleeve; 60 - support part; 61 - stop part; 62 - positioning hole; 7 - elastic reset mechanism; 8 - limiting part; 80 - through hole; 9 - blank pick-up push rod; 100 - wire blank; 101 - first stepped blank; 102 - second stepped blank; 103 - third stepped blank; 104 - fourth stepped blank; 105 - bolt to be upset-toothed; 106 - waste Detailed implementation mode

[0059] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0060] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0061] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0062] Embodiment 1

[0063] The cold heading die provided in this embodiment is used for cold heading and forming the tooth shape of the head of a bolt.

[0064] SeeFigures 1 to 9 In combination with Figures 10 to 12 As shown, the cold heading die provided in this embodiment is used to process bolts with a toothed head. The cold heading die includes a moving die sleeve 2, a stationary die sleeve 1, a punch assembly 3, and a waste ejecting assembly 4.

[0065] In the following, the above components of the cold heading die will be specifically described.

[0066] A toothed machining hole 50 is formed inside the stationary die sleeve 1. A cutting edge 51 is provided at an end of the edge of the toothed machining hole 50 close to the moving die sleeve 2. Among them, the edge includes both the edge extending radially along the toothed machining hole 50 and the edge extending circumferentially along the toothed machining hole 50. In addition, the cutting edge 51 can be formed by a cemented carbide coating, or a sharp cutting edge 51 is obtained after machining the edge of the toothed machining hole 50.

[0067] The punch assembly 3 is arranged in the moving die sleeve 2. The punch assembly 3 protrudes from the moving die sleeve 2 towards the toothed machining hole 50 by a predetermined distance. The predetermined distance is not less than the target thickness of the toothed head. At least a part of the punch assembly 3 within the predetermined distance is adapted to the toothed machining hole 50; the moving die sleeve 2 can move relative to the stationary die sleeve 1 to drive the punch assembly 3 in and out of the toothed machining hole 50. Specifically, during the process of heading the toothed bolt 105, first place the cold heading bolt to be processed in the stationary die sleeve 1, and then the punch assembly 3 moves close to the stationary die sleeve 1 with the moving die sleeve 2 until the punch assembly 3 extends into the toothed machining hole 50 and pushes the toothed bolt 105 to be headed into the toothed machining hole 50. As the toothed bolt 105 to be headed is pushed in, the cutting edge 51 cuts the head of the toothed bolt 105 to be headed, so that the head of the toothed bolt 105 to be headed forms teeth.

[0068] The thickness of the punch assembly 3 and the length extending into the toothed machining hole 50 are not less than the thickness of the head of the toothed bolt 105 to be headed, so as to ensure that the cutting edge 51 cuts through the toothed bolt 105 to be headed in the thickness direction of the head of the toothed bolt 105 to be headed.

[0069] The waste ejecting assembly 4 includes a connecting seat and a plurality of ejector pins 40 connected to the connecting seat. The connecting seat plays a role in fixedly installing the ejector pins 40. The plurality of ejector pins 40 correspond one by one to a plurality of tooth gaps 31 on the outer side wall of the punch assembly 3. The connecting seat is movably connected to the moving die sleeve 2. The connecting seat can move along the moving die sleeve 2. Thus, by moving the connecting seat along the moving die sleeve 2, the ejector pins 40 can move in and out of the tooth gaps 31. That is, when it is necessary to eject the waste 106, move the connecting seat towards the direction of the stationary die sleeve 1, and the ejector pins 40 can be inserted into the tooth gaps 31. After the waste 106 is ejected, move the connecting seat away from the direction of the stationary die sleeve 1, and the ejector pins 40 can be withdrawn from the tooth gaps 31, so that the punch assembly 3 can perform the next toothed head processing.

[0070] In the cold heading die of this embodiment, the punch assembly 3 includes a separating seat 32 and a punch body 30.

[0071] A first installation through hole 21 is formed inside the moving die sleeve 2. The waste pushing component 4, the separating seat 32 and the punch body 30 are sequentially arranged in the first installation through hole 21. The punch body 30 is located on the side of the separating seat 32 close to the stationary die sleeve 1, and the connecting seat is located on the side of the separating seat 32 away from the stationary die sleeve 1. Thus, the punch body 30 and the waste pushing component 4 are separated by the separating seat 32, avoiding the interference of the waste pushing component 4 with the movement of the punch body 30 when the waste 106 does not need to be pushed out.

[0072] The separating seat 32 is fixedly installed in the first installation through hole 21. One end of the punch body 30 extends into the first installation through hole 21 and is connected to the separating seat 32. The separating seat 32 can also provide the functions of supporting and positioning for the punch body 30. The other end of the punch body 30 extends out of the first installation through hole 21 by a predetermined distance, and the predetermined distance is not less than the thickness of the head of the bolt 105 to be upset with teeth. The outer surface of the punch body 30 is adapted to the inner surface of the tooth-shaped machining hole 50, so that not only can the punch body 30 extend into the tooth-shaped machining hole 50, but also it can provide uniform and comprehensive support for the head of the bolt 105 to be upset with teeth, avoiding the head of the bolt 105 to be upset with teeth from tilting towards the side of the moving die sleeve 2 under the action of the cutting force, thus ensuring the forming quality of the tooth-shaped head of the bolt 105 to be upset with teeth.

[0073] The separating seat 32 is provided with communication holes corresponding to the tooth gaps 31 one by one, and the communication holes communicate the two sides of the separating seat 32.

[0074] Optionally, both the separating seat 32 and the moving die sleeve 2 are provided with connecting threaded holes 33, so that the connecting bolts can fixedly connect the separating seat 32 and the punch body 30 and fixedly connect the separating seat 32 and the moving die sleeve 2 through the connecting threaded holes 33.

[0075] A plurality of ejector pins 40 respectively pass through the plurality of communication holes and extend into the tooth gaps 31. The connecting seat is movably arranged in the first installation through hole 21 to drive the ejector pins 40 to move in the tooth gaps 31. After the pushing operation is completed, the plurality of ejector pins 40 withdraw from the tooth gaps 31 of the punch assembly 3, but do not withdraw from the communication holes, so that the waste pushing component 4 can be circumferentially positioned through the communication holes. There is no need to align the communication holes with the ejector pins 40 for each pushing operation. Through the positioning and holding action of the communication holes, the alignment step is omitted, and the time required for pushing is shortened.

[0076] In an optional solution of this embodiment, the connecting base includes a slide body 41 and a push-pull handle 42; multiple push pins 40 are connected to the end of the slide body 41 facing the partition seat 32, one end of the push-pull handle 42 is connected to the end of the slide body 41 facing away from the partition seat 32, and the other end of the push-pull handle 42 extends out of the first mounting hole 21. The push-pull handle 42 provides a structural foundation for holding the connecting base to move the slide body 41, and the slide body 41 provides a fixed mounting base for the push pins 40.

[0077] Optionally, a scale is provided on the push-pull handle 42 so that the operator can understand the distance the push pin 40 is pushed or pulled through the scale on the push-pull handle 42 .

[0078] Optionally, a first guide sleeve 20 is provided in the first mounting hole 21, the first guide sleeve 20 and the partition seat 32 are abutted against each other, and the outer peripheral side wall of the slide body 41 is adapted to the inner peripheral side wall of the first guide sleeve 20 to guide the reciprocating movement of the slide body 41, that is, the waste ejection assembly 4.

[0079] In an optional solution of this embodiment, the length of the push pin 40 is not less than the sum of the lengths of the punch body 30 and the separator 32, so that as much waste material 106 as possible can be pushed out of the punch body 30. Furthermore, the length of the push pin 40 is greater than the sum of the lengths of the punch body 30 and the separator 32, so as to ensure that the waste material 106 can be completely pushed out of the punch body 30, further shortening the time required to push out the waste material 106.

[0080] In an optional solution of this embodiment, specifically, the cutting edge 51 corresponding to the outer ring edge is the first cutting edge, the cutting edge 51 corresponding to the inner ring edge is the second cutting edge, and the cutting edges 51 corresponding to the two radial edges connected to the first cutting edge are the third and fourth cutting edges, respectively. The cutting edge 51 forms a predetermined angle 52 with the axis of the tooth-shaped processing hole 50, and the end of the cutting edge 51 closer to the movable mold sleeve 2 is farther from the axis of the tooth-shaped processing hole 50 than the end of the cutting edge 51 farther from the movable mold sleeve 2. In other words, the third and fourth cutting edges each form a predetermined angle 52 with the axis of the tooth-shaped processing hole 50, the first cutting edge is farther from the axis of the tooth-shaped processing hole 50 than the second cutting edge, and the first cutting edge is closer to the movable mold sleeve 2 than the second cutting edge.

[0081] It is worth emphasizing that although the outer ring size of the head of the to-be-upset bolt 105 is equal to the outer ring size of the target tooth-shaped head, the head of the to-be-upset bolt 105 will expand during the cutting process, and the cutting edge 51 corresponding to the outer ring edge will also participate in the cutting, cutting off the excess caused by the expansion, which can improve the final yield of the tooth-shaped head.

[0082] In an optional solution of this embodiment, the predetermined angle 52 is 60-80°.

[0083] In an alternative solution of this embodiment, the projection distance 53 of the cutting edge 51 on the axis of the static die sleeve 1 is not less than 1 mm.

[0084] By defining the predetermined angle 52 and the projection distance 53, the forward pressure on the cutting edge 51 can be effectively relieved, the service life of the cold heading die can be effectively extended, and the stability of the cutting performance of the cutting edge 51 can be improved.

[0085] In an alternative solution of this embodiment, the cold heading die further includes a forming part 5 and a support sleeve 6.

[0086] A second installation through hole 80 is formed inside the static die sleeve 1, and the forming part 5 is arranged inside the second installation through hole 80; a positioning hole 62 adapted to the circumferential side wall of the bolt 105 to be upset is formed inside the support sleeve 6; a tooth profile machining hole 50 is formed inside the forming part 5, and at least part of the outer surface of the support sleeve 6 is adapted to the tooth profile machining hole 50, and the support sleeve 6 can move along the tooth profile machining hole 50 by a predetermined distance at least. Specifically, the rod part of the bolt 105 to be upset is arranged inside the positioning hole 62, and the support sleeve 6 is movably and correspondingly arranged inside the tooth profile machining hole 50, so that the support sleeve 6 can provide radial and circumferential positioning for the movement of the bolt 105 to be upset along the tooth profile machining hole 50, ensuring stable and continuous machining of the head of the bolt 105 to be upset exposed outside the support sleeve 6, and avoiding the occurrence of irregular tooth profile machining due to the skew of the bolt 105 to be upset relative to the tooth profile machining hole 50.

[0087] In an alternative solution of this embodiment, the cold heading die further includes a limiting part 8 and an elastic reset mechanism 7.

[0088] The limiting part 8 is arranged inside the second installation through hole 80 and is located on the side of the forming part 5 away from the moving die sleeve 2. The support sleeve 6 includes a support part 60 and a stop part 61. The support part 60 is adapted to the tooth profile machining hole 50, and the stop part 61 is connected to one end of the support part 60 away from the moving die sleeve 2. The stop part 61 is located between the forming part 5 and the limiting part 8 and can abut against the forming part 5, so that the stroke range of the stop part 61 is between the forming part 5 and the limiting part 8, and at the same time, the stroke range of the support sleeve 6 is limited. The distance between the forming part 5 and the limiting part 8 is not less than the thickness of the head of the bolt 105 to be upset.

[0089] The elastic reset mechanism 7 is supported between the limiting part 8 and the stopping part 61, and applies an elastic reset force towards the forming part 5 to the stopping part 61. Thus, when the punch assembly 3 extends into the tooth-shaped processing hole 50, the elastic reset mechanism 7 is compressed as the support sleeve 6 moves towards the limiting part 8. Until the tooth shaping is completed, the punch assembly 3 is pushed out of the tooth-shaped processing hole 50, and the support sleeve 6 loses the pressure towards the elastic reset mechanism 7. Thus, under the action of the elastic reset force of the elastic reset mechanism 7, it returns to its original position, that is, the automatic reset of the support sleeve 6 is realized.

[0090] Optionally, the elastic reset mechanism 7 can be a metal spring, a silica gel spring or a gas spring, etc.

[0091] Optionally, a second guide sleeve 10 is further arranged in the second installation through hole 80. Both ends of the second guide sleeve 10 are respectively abutted against the forming part 5 and the limiting part 8. The inner surface of the second guide sleeve 10 is adapted to the outer surface of the stopping part 61 to guide the reciprocating movement of the stopping part 61, that is, the support sleeve 6.

[0092] In the optional solution of this embodiment, the cold heading die further includes a blank taking push rod 9; the positioning hole 62 penetrates through the supporting part 60 and the stopping part 61; the limiting part 8 is provided with a through hole 80 communicated with the positioning hole 62. One end of the blank taking push rod 9 passes through the through hole 80 and extends into the positioning hole 62, and the other end of the blank taking push rod 9 extends out of the second installation through hole 80.

[0093] In the optional solution of this embodiment, the end face of the static die sleeve 1 facing the moving die sleeve 2 is coated with a cemented carbide wear-resistant coating to extend the service life of the static die sleeve 1.

[0094] Optionally, the material of the cemented carbide wear-resistant coating is titanium nitride.

[0095] Embodiment Two

[0096] Embodiment Two provides a cold heading forming process. This embodiment uses the cold heading die of Embodiment One. The technical features of the cold heading die disclosed in Embodiment One are also applicable to this embodiment, and the technical features of the cold heading die already disclosed in Embodiment One will not be described repeatedly.

[0097] Combined with Figure 1 and Figure 9 and referring to Figure 10 and up to Figure 12 As shown, the cold heading forming process provided in this embodiment specifically includes the following steps:

[0098] Step S700, cutting the wire blank 100 to form a first stepped blank 101, and the cross-sectional area of the first stepped blank 101 is larger than the cross-sectional area of the tooth-shaped head bolt.

[0099] Step S710, pre-shrinking the screw portion of the first stepped blank 101 to obtain a second stepped blank 102, wherein the cross-sectional area of the second stepped blank 102 is reduced by 20-30% compared to the cross-sectional area of the first stepped blank 101;

[0100] Step S720: pre-upsetting the second stepped blank 102 to obtain a third stepped blank 103. The height of the head of the third stepped blank 103 is lower than that of the second stepped blank 102.

[0101] Step S730: The third stepped blank 103 is pre-upset twice to obtain a fourth stepped blank 104. The height of the head of the third stepped blank 103 is 1.5-1.8 times the height of the head of the fourth stepped blank 104. The diameter of the head of the third stepped blank 103 is 0.75-0.8 times the diameter of the head of the fourth stepped blank 104.

[0102] Step S740, performing chamfering and upsetting on the screw portion of the fourth stepped blank 104 and upsetting the blank diameter to obtain the bolt 105 to be upset;

[0103] In step S750 , the cold heading die provided in the first embodiment is used to perform tooth forming on the head of the toothed bolt 105 to be forged.

[0104] In this embodiment, in step S710, by cutting the wire blank 100, the initial upsetting ratio of the subsequent upsetting steps S720 and S7230 can be reduced, thereby reducing the difficulty of upsetting. Optionally, the cross-sectional area of the wire blank 100 is 1.2-1.3 times the cross-sectional area of the first stepped blank 101. In order to ensure that the final bolt with a toothed head can meet the quality requirements, it is necessary to ensure that the volume of the wire blank 100 is equal to the volume of the final formed bolt. Specifically, as Figure 12 , the wire blank 100 is a rod of equal diameter, and its radius is D, as shown in FIG. Figure 10 As shown, the diameter of the head of the first stepped blank 101 is D, and the diameter of the stem is reduced; the minimum diameter of the head of the second stepped blank 102 is D, and the diameter of the rest of the head is increased.

[0105] The upsetting steps of steps S720 and S730 make the head height and head diameter of the fourth step-shaped blank 104 equal to the target height and target outer diameter of the toothed head of the bolt. Figure 10 As shown, in step S720, after upsetting, the diameter of the head of the third stepped blank 103 is D1, and a round cap protrusion is formed at one end of the head away from the stem. The thickness after upsetting is H. In step S730, upsetting is continued, the thickness is reduced to H1, and the round cap protrusion is upset flat, resulting in a fourth stepped blank 104 with a head diameter of D2.

[0106] The bolt is finish - machined through step S740 to form a transition shoulder with a diameter of d between the rod part and the head, which is beneficial to protecting the cold - heading die in step S750.

[0107] Through step S750, tooth - shape machining is performed on the head of the bolt, so that the outer - ring diameter of the head remains at D2, and the inner - ring diameter of the head is D3.

[0108] The cold - heading forming process in this embodiment has the advantages of the cold - heading die in Embodiment 1, and the advantages of the cold - heading die disclosed in Embodiment 1 will not be repeated here.

[0109] Finally, it should be noted that: the above - mentioned embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent substitution on some or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. In addition, those skilled in the art can understand that although some of the embodiments described herein include certain features included in other embodiments but not other features, the combination of the features of different embodiments means that it is within the scope of the present invention and forms different embodiments. For example, any one of the claimed embodiments can be used in any combination. The information disclosed in this background - art section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art known to those skilled in the art.

Claims

1. A cold heading die for machining bolts with a toothed head, characterized in that, The cold heading die comprises a movable die sleeve, a static die sleeve, a punch assembly and a waste ejection assembly; A tooth-shaped processing hole is formed inside the static die sleeve, and a cutting edge is provided at the end of the edge of the tooth-shaped processing hole close to the movable die sleeve; The punch assembly is disposed on the movable die sleeve, the punch assembly protruding from the movable die sleeve toward the tooth-shaped processing hole by a predetermined distance, the predetermined distance being no less than a target thickness of the tooth-shaped head, and at least a portion of the punch assembly within the predetermined distance being adapted to the tooth-shaped processing hole; The movable die sleeve is movable relative to the static die sleeve to drive the punch assembly to enter and exit the tooth-shaped processing hole; The waste ejection assembly includes a connecting seat and a plurality of ejection pins connected to the connecting seat, wherein the plurality of ejection pins correspond one to one with the plurality of inter-tooth gaps on the outer side wall of the punch assembly; The connecting seat is movably connected to the movable mold sleeve, and the connecting seat can move along the movable mold sleeve so that the ejector pin can enter and exit the gap between the teeth; The punch assembly includes a separator and a punch body; A first mounting through hole is provided inside the movable die sleeve, and the waste ejection assembly, the partition seat, and the punch body are sequentially arranged in the first mounting through hole, the punch body is located on a side of the partition seat close to the static die sleeve, and the connecting seat is located on a side of the partition seat away from the static die sleeve; The separator is fixedly mounted in the first mounting through hole, one end of the punch body extends into the first mounting through hole and is connected to the separator, and the other end of the punch body extends out of the first mounting through hole by a predetermined distance, and the outer surface of the punch body is adapted to the inner surface of the tooth-shaped processing hole; The separator is provided with communication holes corresponding to the gaps between the teeth, and the communication holes connect the two sides of the separator; The plurality of push pins pass through the plurality of communicating holes in a one-to-one correspondence and extend into the inter-tooth gaps. The connecting seat is movably disposed in the first mounting through hole to drive the push pins to move in the inter-tooth gaps. The connecting seat includes a sliding seat body and a push-pull handle; A plurality of push pins are connected to one end of the slide body facing the partition seat, one end of the push-pull handle is connected to one end of the slide body facing away from the partition seat, and the other end of the push-pull handle extends out of the first mounting through hole; The length of the push pin is not less than the sum of the lengths of the punch body and the partition seat.

2. The cold heading die according to claim 1, characterized in that, The cutting edge forms a predetermined angle with the axis of the tooth-shaped processing hole, and the end of the cutting edge close to the movable mold sleeve is farther from the axis of the tooth-shaped processing hole than the end of the cutting edge away from the movable mold sleeve.

3. The cold heading die according to claim 2, characterized in that, The predetermined angle is 60-80°; And / or, the projection distance of the cutting edge on the axis of the static die sleeve is not less than 1 mm.

4. The cold heading die according to claim 1, characterized in that, Also includes a forming portion and a support sleeve; A second mounting through hole is formed inside the static mold sleeve, and the forming portion is arranged in the second mounting through hole; A positioning hole is formed inside the support sleeve to match the circumferential side wall of the bolt to be upset; The tooth-shaped processing hole is formed inside the forming portion, a portion of the outer surface of the support sleeve is adapted to the tooth-shaped processing hole, and the support sleeve can at least move the predetermined distance along the tooth-shaped processing hole.

5. The cold heading die according to claim 4, characterized in that, It also includes a limiting portion and an elastic reset mechanism; The limiting portion is arranged in the second mounting through hole and is located on a side of the forming portion away from the movable mold sleeve; The support sleeve includes a support portion and a stop portion, the support portion is adapted to the tooth-shaped processing hole, the stop portion is connected to an end of the support portion away from the movable mold sleeve, the stop portion is located between the forming portion and the limiting portion and can abut against the forming portion; The elastic restoring mechanism is supported between the limiting portion and the stopping portion, and applies an elastic restoring force toward the forming portion to the stopping portion.

6. The cold heading die according to claim 5, characterized in that, Also includes a reclaim push rod; The positioning hole passes through the supporting portion and the stopping portion; The limiting portion is provided with a through hole communicating with the positioning hole, one end of the material taking push rod passes through the through hole and extends into the positioning hole, and the other end of the material taking push rod extends out of the second mounting through hole; And / or, the end surface of the static die sleeve facing the dynamic die sleeve is coated with a hard alloy wear-resistant coating.

7. A cold heading forming process for machining bolts with toothed heads, characterized in that, The cold heading forming process specifically includes the following steps: cutting the wire blank to form a first stepped blank, wherein the cross-sectional area of the first stepped blank is larger than the cross-sectional area of the toothed head bolt; Pre-shrinking the screw portion of the first step-shaped billet to obtain a second step-shaped billet, wherein the cross-sectional area of the second step-shaped billet is reduced by 20-30% compared with the cross-sectional area of the first step-shaped billet; The second step-shaped blank is pre-upset to obtain a third step-shaped blank, wherein the head height of the third step-shaped blank is lower than that of the second step-shaped blank; The third step-shaped blank is subjected to secondary pre-upsetting to obtain a fourth step-shaped blank, wherein the head height of the third step-shaped blank is 1.5-1.8 times the head height of the fourth step-shaped blank, and the head diameter of the third step-shaped blank is 0.75-0.8 times the head diameter of the fourth step-shaped blank; The screw portion of the fourth step-shaped blank is subjected to chamfering and upsetting as well as blank diameter upsetting to obtain a bolt to be upset; The cold heading die according to any one of claims 1 to 6 is used to perform tooth shaping on the head of a bolt to be headed.

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