A cold heading die for high-precision processing of a bolt and a cold heading process thereof

Abstract

The application relates to the field of bolt manufacturing and discloses a cold heading die for high-precision processing of bolts, which comprises a movable die component and a fixed die component, the fixed die component comprises a fixed column shell, an upper end cover is arranged at the upper opening end of the fixed column shell, a coaxial upper mounting groove is arranged on the end face of the upper end cover, a lower avoiding hole is coaxially arranged at the groove bottom of the upper mounting groove, a bracket is sleeved in the upper mounting groove, a bracket groove matched with the shape of a blank bolt head is arranged on the upper surface of the bracket, a penetrating hole is arranged at the groove bottom of the bracket groove, a third spring is arranged between the bracket and the groove bottom of the upper mounting groove, a tooth plate is radially slidably arranged in the fixed column shell, the side of the tooth plate facing the axis of the fixed column shell is arranged as a curved surface, and thread rolling is arranged on the curved surface, a plurality of tooth plates are arrayed along the circumferential direction of the fixed column shell, the curved surfaces of all the tooth plates can form a complete cylindrical outer surface, and the cylindrical outer surface is coaxial with the fixed column shell.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bolt manufacturing, in particular to the field of bolt cold heading, and particularly relates to a cold heading die for high-precision processing of bolts and a cold heading process thereof. BACKGROUND

[0002] A thread cold heading machine is a high-efficiency cold forming equipment for mass production of threaded fasteners (such as bolts, screws, studs, etc.), which realizes high-efficiency and high-precision thread forming through cold heading + thread rolling, and its cold heading process includes shearing a wire rod into a preset length to obtain a blank, heading the blank into a preset shape, and thread rolling the blank, wherein the thread quality obtained by rolling is one of the important factors affecting the production precision of the fastener.

[0003] In the prior art, the blank is sent between a plurality of thread rolling wheels of a thread rolling machine, and through the rotation of the thread rolling wheels, the blank is driven to rotate and axially feed, and at the same time, the tooth profile of the thread rolling wheel continuously extrudes the surface of the blank to form a thread. This method has some disadvantages, for example: on the one hand, the thread rolling wheel is generally 2-3, and when used, if the blank is not calibrated, it has a taper and diameter fluctuation, so that the roundness deviation of the thread after rolling is easy to occur, and in addition, the uneven pressure of the thread rolling wheel also easily causes the roundness deviation, which may cause local deformation or ovalization; on the one hand, when used, the blank is directly subjected to cold plastic deformation according to the set requirements, that is, the thread is formed in one step, without a gradual process, and since the cold plastic deformation belongs to chipless machining, the material is not cut off, but only displaced and redistributed, so that the material is directly subjected to large plastic deformation, which easily affects the final thread quality; on the one hand, when processing the thread, it is generally necessary to spray lubricant to the processing area, but the thread rolling machine is generally open or has a shell outside, and this method cannot make the sprayed lubricant act between the thread rolling wheel and the blank to the greatest extent, and the utilization rate of the lubricant is low.

[0004] Based on the above, the present application provides a cold heading die for high-precision processing of bolts and a cold heading process thereof. SUMMARY

[0005] To solve the problems mentioned in the background, the present application provides a cold heading die for high-precision processing of bolts and a cold heading process thereof.

[0006] To achieve the above technical purposes, the technical solutions adopted by the present application are as follows.

[0007] A cold heading die for high-precision processing of bolts, comprising a movable die member and a fixed die member.

[0008] The fixed mold member comprises a fixed column shell arranged vertically, the upper end of the fixed column shell is open and provided with an upper end cover, the lower end is closed, the end face of the upper end cover is coaxially provided with an upper mounting groove, the groove bottom of the upper mounting groove is coaxially provided with a lower avoiding hole, a bracket is sleeved in the upper mounting groove, the upper surface of the bracket is provided with a bracket groove matched with the shape of the blank bolt head, the groove bottom of the bracket groove is provided with a through hole, and the third spring is arranged between the bracket and the groove bottom of the upper mounting groove;

[0009] The inside of the fixed column shell is radially slidably provided with a die plate, the side of the die plate facing the axis of the fixed column shell is arranged as an arc surface, and the arc surface is provided with a rolling thread, a plurality of die plates are arranged in the circumferential direction of the fixed column shell, and the arc surfaces of all the die plates can form a complete cylindrical outer cylindrical surface coaxial with the fixed column shell;

[0010] The fixed mold member further comprises a driving assembly for driving the die plate to move with the downward movement of the movable mold member.

[0011] Further, the side of the die plate away from the axis of the fixed column shell is arranged as an inclined surface one, and the distance between the inclined surface one and the axis of the fixed column shell decreases from bottom to top;

[0012] The driving assembly comprises a push seat slidably arranged in the fixed column shell in the vertical direction, the side of the push seat facing the axis of the fixed column shell is arranged as an inclined surface two, the inclined surface one and the inclined surface two are attached and form a sliding connection in the inclined direction of the inclined surface one, the number of push seats corresponds to the number of die plates, the upper surface of the push seat is provided with a convex rod, the upper end of the convex rod protrudes out of the fixed column shell, and all the convex rods are connected through a fixed ring.

[0013] Further, the movable mold member comprises an outer pressure column coaxially located above the fixed column shell, the lower end face of the outer pressure column is coaxially provided with a lower mounting groove, and the groove bottom of the lower mounting groove is coaxially provided with an upper mounting hole;

[0014] The upper mounting hole is coaxially installed with a rotating shaft and a connecting piece and a coil spring is arranged therebetween, when the relative displacement between the outer pressure column and the rotating shaft occurs, the rotating shaft can be driven to rotate through the connecting piece.

[0015] Further, the upper end of the rotating shaft is provided with a insertion slot, one end of the coil spring is connected with the upper mounting hole, and the other end is inserted into the insertion slot.

[0016] Further, the connecting piece comprises a spiral convex strip arranged on the hole wall of the upper mounting hole and a spiral sliding groove arranged on the outer cylindrical surface of the rotating shaft, and the spiral convex strip is located in the spiral sliding groove.

[0017] Further, the lower end of the rotating shaft is coaxially provided with a limiting ring column, a first spring is arranged between the upper end of the limiting ring column and the groove bottom of the lower mounting groove, the lower end surface of the rotating shaft is coaxially provided with a spline groove, a plug shaft is arranged in the spline groove, and the lower end of the plug shaft is arranged in a shape matched with the internal hexagonal hole of the bolt head of the blank;

[0018] The blank is sent into the fixed mold member, the bolt head of the blank is supported by the support, the lower end of the plug shaft is first inserted into the internal hexagonal hole of the bolt head of the blank during the descending process of the outer pressing column, then the outer pressing column continues to descend, the second spring is compressed, and when the compression amount of the second spring reaches the maximum, the lower end of the limiting ring column is in contact with the groove opening of the upper mounting groove, and at the same time, the lower end of the outer pressing column is in contact with the upper end of the fixed ring.

[0019] Further, the plug shaft is arranged in the spline groove through the spline, and when the relative displacement occurs between the plug shaft and the rotating shaft, the power connection is maintained between the plug shaft and the rotating shaft through the spline, and the second spring is arranged between the plug shaft and the groove bottom of the spline groove.

[0020] Further, the lower closed end of the fixed column shell is coaxially provided with a ring groove, a lower end cover is arranged at the groove opening of the ring groove, a piston is sleeved in the ring groove, a fourth spring is arranged between the piston and the lower end cover, a connecting rod is arranged at the bottom of the push seat, and the lower end of the connecting rod extends into the ring groove and is connected with the piston;

[0021] A first channel is arranged in the fixed column shell, a connecting hole in communication with the first channel is arranged at the groove wall of the ring groove, a first one-way valve is arranged in the first channel, and the first one-way valve is used for allowing the lubricant in the ring groove to flow into the first channel in one direction;

[0022] An inlet is arranged on the lower end cover, a second one-way valve is arranged at the inlet, and the second one-way valve is used for allowing the external lubricant to flow into the ring groove in one direction;

[0023] An outlet is coaxially arranged at the end surface of the lower end cover, an output pipe is arranged at the lower hole opening of the outlet, and the outlet is in communication with the thread processing area;

[0024] A second channel is arranged in the push seat, the area between the arc surfaces of the plurality of toothed plates is named as the thread processing area, and the second channel is used for realizing the communication between the first channel and the thread processing area.

[0025] A cold heading process of a cold heading die for high-precision processing of a bolt includes the following steps:

[0026] Step one: the blank is sent into the fixed mold member, and the bolt head of the blank is supported by the support;

[0027] Step two: drive the outer pressure column to move down, during the moving down process, the lower end of the shaft is inserted into the inner hexagonal hole of the blank bolt head first, then the outer pressure column continues to move down, the second spring is compressed, when the compression amount of the second spring reaches the maximum, the lower end of the limiting ring column contacts with the notch of the upper mounting groove, at the same time, the lower end of the outer pressure column contacts with the upper end of the fixed ring;

[0028] Step three: the outer pressure column continues to move down and pushes the fixed ring to move down together, so that the tooth plate gradually closes to form a complete cylindrical outer surface, that is, the rolling thread on the tooth plate arc surface gradually extrudes the blank, at the same time, the outer pressure column moving down can make the rotating shaft rotate through the connecting member, the rotating shaft rotates with the shaft and the blank, the blank rotates and moves down at the same time, the thread processing is realized by gradually extruding the blank through the rolling thread and rotating and moving down of the blank;

[0029] At the same time, the push seat moves down with the piston, so as to push the lubricant in the ring groove, the lubricant flows into the thread processing area through the connecting hole, the first one-way valve, the first channel and the second channel in turn, and the lubrication purpose is realized, the lubricated lubricant flows downward under the action of gravity, and is output outward through the outlet and the output pipe.

[0030] Compared with the prior art, the present application has the beneficial effects that:

[0031] The present application gradually extrudes the blank through the rolling thread on the tooth plate arc surface, and rotates and moves down of the blank, so as to realize the processing of the thread, which has the advantages that: 1, after the processing of the thread is completed, the bolt screw part of the blank is located in the complete cylindrical outer surface, so that the coaxial correction purpose can be achieved, the coaxiality of the bolt screw part is ensured, so that the first problem mentioned in the background art is solved; 2, during the thread processing, the rolling thread gradually extrudes the blank, that is, the thread on the blank is not formed in one step, but has a circulating and progressive extrusion and deformation process of plastic, therefore, compared with the one-step method, the thread processed by the present application has higher quality, and the second problem mentioned in the background art is solved; 3, during the thread processing of the present application, the tooth plate is gradually closed, therefore, the lubricant can smoothly flow into the rolling thread and be distributed at each position of the rolling thread, the lubrication effect is better, and the lubricant can be maximized at the thread processing position, the utilization rate of the lubricant is higher, that is, less lubricant can achieve the desired lubrication effect during processing, and the third problem mentioned in the background art is solved. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The structure of the present application Figure 1 ;

[0033] Figure 2 The structure of the present application Figure 2 ;

[0034] Figure 3 is a sectional view of the present application;

[0035] Figure 4 is a sectional view of the movable die member;

[0036] Figure 5 is a partial exploded view of the movable die member;

[0037] Figure 6 is a whole sectional view of the fixed die member;

[0038] Figure 7 is a partial sectional view of the fixed die member Figure 1 ;

[0039] Figure 8 is a partial sectional view of the fixed die member Figure 2 ;

[0040] Figure 9 is a schematic view of the push seat and the tooth plate.

[0041] Reference signs in the drawings are:

[0042] 100, movable die member; 101, outer pressure column; 1011, lower mounting groove; 1012, upper mounting hole; 1013, helical protrusion; 102, rotating shaft; 1021, helical sliding groove; 1022, spline groove; 103, coil spring; 104, limit ring column; 105, first spring; 106, insertion shaft; 107, second spring; 200, fixed die member; 201, fixed column shell; 2011, upper end cover; 2012, upper mounting groove; 2013, lower avoiding hole; 2014, ring groove; 2015, lower end cover; 2016, connecting hole; 2017, first channel; 2018, first one-way valve; 202, tooth plate; 203, push seat; 2031, protruding rod; 2032, fixed ring; 2033, second channel; 204, support seat; 205, third spring; 206, top rod; 207, piston; 208, fourth spring. DETAILED DESCRIPTION

[0043] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined purposes, the specific embodiments, structures, features and effects according to the present application are described in detail as follows in combination with the drawings and preferred embodiments.

[0044] In the drawings of the present application, a refers to a bolt.

[0045] The present application realizes thread processing by cold heading, and one of the cores is the cold heading die used for thread processing.

[0046] Example 1

[0047] Refer toFigures 1-9 The utility model provides a cold heading die for high-precision bolt processing, which comprises a movable die component 100 and a fixed die component 200, and in use, a blank is fed into the fixed die component 200, and then the movable die component 100 is driven to move downward, and during the downward movement, the thread of the blank is processed through the cooperation between the movable die component 100 and the fixed die component 200.

[0048] The fixed die component 200 comprises a fixed column shell 201 arranged vertically.

[0049] With reference to Figures 6-9 The fixed die component 200 comprises a fixed column shell 201 arranged vertically.

[0050] The upper end of the fixed column shell 201 is open and provided with an upper end cover 2011, and the lower end is closed; the end face of the upper end cover 2011 is coaxially provided with an upper mounting groove 2012, and the groove bottom of the upper mounting groove 2012 is coaxially provided with a lower avoiding hole 2013; a bracket 204 is sleeved in the upper mounting groove 2012, and the shape of the bracket 204 is consistent with the shape of the bolt head of the blank, that is, the upper surface of the bracket 204 is provided with a bracket groove in a hexagonal shape, and the groove bottom of the bracket groove is provided with a through hole for avoiding the bolt shank of the blank, so that the bracket 204 places the bolt head of the blank through the bracket groove and limits the movement of the blank along the radial direction; and the bracket 204 and the upper mounting groove 2012 are provided with a third spring 205.

[0051] The inside of the fixed column shell 201 is radially slidably provided with a die plate 202, the side of the die plate 202 facing the axis of the fixed column shell 201 is arranged as an arc surface, and the arc surface is provided with a rolling thread; the die plate 202 is arranged in an array along the circumferential direction of the fixed column shell 201, and the arc surfaces of all the die plates 202 can form a complete cylindrical outer cylindrical surface, and the cylindrical outer cylindrical surface has a complete rolling thread, and the cylindrical outer cylindrical surface is coaxial with the fixed column shell 201.

[0052] The fixed mold member 200 further comprises a driving assembly for driving the movement of the toothed plate 202. Specifically, the side of the toothed plate 202 away from the axis of the fixed column shell 201 is provided with an inclined surface I, and the distance between the inclined surface I and the axis of the fixed column shell 201 decreases from bottom to top. The driving assembly comprises a push seat 203 slidingly arranged in the fixed column shell 201 in the vertical direction. The side of the push seat 203 toward the axis of the fixed column shell 201 is provided with an inclined surface II. The inclined surface I and the inclined surface II are attached and constitute a sliding connection in the inclined direction of the inclined surface I. Therefore, when the push seat 203 moves downward, the toothed plate 202 can be pushed to move close to the axis of the fixed column shell 201. When the adjacent toothed plates 202 are attached to each other, the complete cylindrical outer surface mentioned above is formed. Conversely, when the push seat 203 moves upward, the toothed plate 202 can be pulled to move away from the axis of the fixed column shell 201. The push seat 203 is correspondingly provided with a plurality of push rods 2031 on the upper surface. The upper ends of the push rods 2031 extend out of the fixed column shell 201 through the upper end cover 2011. All the push rods 2031 are connected by a fixed ring 2032. The movement of the push seat 203 is driven by driving the fixed ring 2032.

[0053] The movable mold member 100:

[0054] Referring to Figure 4 With Figure 5 , the movable mold member 100 comprises an outer pressure column 101 coaxially located above the fixed column shell 201. The lower end surface of the outer pressure column 101 is coaxially provided with a lower mounting groove 1011. The groove bottom of the lower mounting groove 1011 is coaxially provided with an upper mounting hole 1012.

[0055] A rotating shaft 102 is coaxially mounted in the upper mounting hole 1012 and a linkage and a coil spring 103 are arranged therebetween. The upper end of the rotating shaft 102 is provided with a slot. One end of the coil spring 103 is connected with the upper mounting hole 1012, and the other end is inserted into the slot. Therefore, when the rotating shaft 102 moves with reference to the coil spring 103, the coil spring 103 still maintains the connection with the rotating shaft 102. When the relative displacement occurs between the outer pressure column 101 and the rotating shaft 102, the rotating shaft 102 can be driven to rotate by the linkage. Specifically, the linkage comprises a spiral protrusion 1013 arranged on the hole wall of the upper mounting hole 1012 and a spiral sliding groove 1021 arranged on the outer surface of the rotating shaft 102. The spiral protrusion 1013 is located in the spiral sliding groove 1021. Preferably, the pitch of the spiral protrusion 1013 and the spiral sliding groove 1021 is relatively large. Therefore, when the relative displacement occurs between the outer pressure column 101 and the rotating shaft 102, the rotating shaft 102 can be rotated by the cooperation of the spiral protrusion 1013 and the spiral sliding groove 1021.

[0056] The lower end of the rotating shaft 102 is coaxially provided with a limiting ring column 104, and the upper end of the limiting ring column 104 is provided with a first spring 105 between the groove bottom of the lower mounting groove 1011.

[0057] The lower end surface of the rotating shaft 102 is coaxially provided with a spline groove 1022, the spline groove 1022 is provided with a plug shaft 106 through spline, and when the relative displacement occurs between the plug shaft 106 and the rotating shaft 102, the power connection is kept between the two through spline, and the second spring 107 is provided between the plug shaft 106 and the groove bottom of the spline groove 1022.

[0058] The lower end of the plug shaft 106 is provided with a shape matched with the internal hexagonal hole of the blank bolt head.

[0059] The blank is sent into the fixed mold member 200, the bolt head of the blank is supported by the bracket 204, then the outer pressing column 101 is driven to move downward through the existing hydraulic technology, in the process of moving downward, the lower end of the plug shaft 106 is first inserted into the internal hexagonal hole of the bolt head of the blank, then the outer pressing column 101 continues to move downward, the second spring 107 is compressed, when the compression amount of the second spring 107 reaches the maximum, the lower end of the limiting ring column 104 contacts with the slot of the upper mounting groove 2012, at the same time, the lower end of the outer pressing column 101 contacts with the upper end of the fixed ring 2032.

[0060] Then, the outer pressing column 101 continues to move downward, the outer pressing column 101 pushes the fixed ring 2032 to move downward together, so that the tooth plate 202 is gradually closed to form a complete cylindrical outer cylindrical surface, that is, the rolling thread on the arc surface of the tooth plate 202 gradually extrudes the blank, at the same time, the rotating shaft 102 is rotated through the linkage, the rotating shaft 102 rotates with the plug shaft 106 and the blank, because of the existence of the rolling thread, therefore, the blank rotates and moves downward at the same time, that is, the rolling thread on the arc surface of the tooth plate 202 gradually extrudes the blank, plus the blank rotates and moves downward at the same time, so as to realize the processing of the thread, the advantages are: 1, after the processing of the thread is completed, the bolt screw part of the blank is located in the complete cylindrical outer cylindrical surface, therefore, the coaxial correction purpose can be achieved, the coaxiality of the bolt screw part is ensured, so as to solve the first problem mentioned in the background art; 2, during the thread processing, the rolling thread gradually extrudes the blank, that is, the thread on the blank is not formed in one step, but has a circulating and progressive extrusion and plastic deformation process, therefore, compared with the one-step method, the thread quality processed by the present scheme is higher, and the problem 2 mentioned in the background art is solved.

[0061] In addition, during the thread processing, when the blank rotates and moves downward at the same time, the second spring 107 continuously releases the elastic force, so that the plug shaft 106 continuously inserts into the internal hexagonal hole of the bolt head of the blank, and the action of the blank rotating and moving downward at the same time can be smoothly continued.

[0062] In the preferred embodiment, referring to Figure 6 After the thread processing, a top hole can be coaxially arranged at the lower closed end of the fixed column shell 201, and a top rod 206 is arranged in the top hole. The top rod 206 is a telescopic rod structure, for example, an electric telescopic rod. The blank is pushed out through the top rod 206, which facilitates the output of the processed blank.

[0063] Embodiment two

[0064] In the thread processing of embodiment one, a lubricant needs to be sprayed to the processing position. Therefore, embodiment two is proposed.

[0065] Referring to Figures 6-9 The lower closed end of the fixed column shell 201 is coaxially provided with an annular groove 2014, and the annular groove 2014 is provided with a lower end cover 2015 at the groove opening. A piston 207 is sleeved in the annular groove 2014, and a fourth spring 208 is arranged between the piston 207 and the lower end cover 2015. The bottom of the push seat 203 is provided with a connecting rod, and the lower end of the connecting rod extends into the annular groove 2014 and is connected with the piston 207. Therefore, the movement of the push seat 203 drives the piston 207 to move.

[0066] The first channel 2017 is arranged in the fixed column shell 201, and the groove wall of the annular groove 2014 is provided with a connecting hole 2016 in communication with the first channel 2017. The first one-way valve 2018 is arranged in the first channel 2017, and is used to allow the lubricant in the annular groove 2014 to flow into the first channel 2017 in one direction.

[0067] The lower end cover 2015 is provided with an inlet, and a second one-way valve is arranged at the inlet. The second one-way valve is used to allow the lubricant outside to flow into the annular groove 2014 in one direction, for example, the lubricant is injected into the inlet through peristaltic pump, water pump or other technologies. Further, the diameter of the top hole mentioned above is larger than the diameter of the top rod 206. The end face of the lower end cover 2015 is coaxially provided with an outlet, and a sleeve is arranged in the outlet through a support. The top rod 206 is sleeved in the sleeve. The lower hole of the outlet is further provided with an output pipe, and the output pipe is provided with an avoiding hole for avoiding the top rod 206. The outlet is in communication with the top hole. Therefore, the used lubricant can be outputted outside through the top hole, the outlet and the output pipe. The inlet and the second one-way valve are not shown in the figure.

[0068] The second channel 2033 is arranged in the push seat 203, and the area between the arc surfaces of the plurality of tooth plates 202 is named as the thread processing area. The second channel 2033 is used to realize the communication between the first channel 2017 and the thread processing area.

[0069] Working process of embodiment two:

[0070] During the thread processing, the push seat 203 moves downward, and the piston 207 moves downward together, so as to push the lubricant in the ring groove 2014, and the lubricant flows into the thread processing area through the connecting hole 2016, the first one-way valve 2018, the first channel 2017 and the second channel 2033 in sequence, so as to achieve the lubricating purpose. The lubricant flows downward under the action of gravity, and is outputted outward through the top hole, the outlet and the output pipe. In addition, the lubricant can be supplemented into the ring groove 2014 through the existing peristaltic pump, water pump and the like.

[0071] It should be noted that, referring to Figure 7 , the beginning situation is shown, and as the push seat 203 moves downward, the second channel 2033 is in communication with the thread processing area.

[0072] As known from the above, during the thread processing, the lubricant can be maximized to act on the thread processing position, and the utilization rate of the lubricant is higher, that is, during the processing, less lubricant can achieve the desired lubricating effect, so as to solve the third problem mentioned in the background art. In addition, since the die plate 202 is gradually closed during the thread processing of the present scheme, the lubricant can smoothly flow into the rolled thread and be distributed at each position of the rolled thread, so that the lubricating effect is better.

[0073] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, change, equivalent change and modification of the above embodiments according to the technical essence of the present application, which does not depart from the technical solution of the present application, still belongs to the scope of the technical solution of the present application.

Claims

1. A cold heading die for high-precision bolt machining, characterized in that, The die assembly comprises a fixed die member and a movable die member; The fixed die member comprises a fixed column shell arranged vertically, the upper end of the fixed column shell is open and provided with an upper end cover, the lower end is closed, the end face of the upper end cover is coaxially provided with an upper mounting groove, the groove bottom of the upper mounting groove is coaxially provided with a lower avoiding hole, a bracket is sleeved in the upper mounting groove, the upper surface of the bracket is provided with a bracket groove matched with the shape of the blank bolt head, the groove bottom of the bracket groove is provided with a through hole, the bracket and the groove bottom of the upper mounting groove are provided with a third spring; The inside of the fixed column shell is radially slidably provided with a die plate, the side of the die plate facing the axis of the fixed column shell is arranged as an arc surface and the arc surface is provided with a rolling thread, a plurality of die plates are arranged in the circumferential direction of the fixed column shell, and the arc surfaces of all the die plates can form a complete cylindrical outer cylindrical surface coaxial with the fixed column shell; The fixed die member further comprises a driving assembly for driving the die plate to move with the downward movement of the movable die member; The driving assembly comprises a push seat slidably arranged in the fixed column shell in the vertical direction; The movable die member comprises an outer pressure column coaxially located above the fixed column shell, the lower end face of the outer pressure column is coaxially provided with a lower mounting groove, and the groove bottom of the lower mounting groove is coaxially provided with an upper mounting hole; A rotating shaft is coaxially installed in the upper mounting hole and a linkage and a coil spring are arranged therebetween, when the outer pressure column and the rotating shaft are relatively displaced, the rotating shaft is driven to rotate through the linkage; The lower closed end of the fixed column shell is coaxially provided with an annular groove, the annular groove is provided with a lower end cover at the groove opening, a piston is sleeved in the annular groove, a fourth spring is arranged between the piston and the lower end cover, the bottom of the push seat is provided with a connecting rod, the lower end of the connecting rod extends into the annular groove and is connected with the piston; A first channel is arranged in the fixed column shell, the groove wall of the annular groove is provided with a connecting hole in communication with the first channel, a first one-way valve is arranged in the first channel, and the first one-way valve is used to make the lubricant in the annular groove flow into the first channel in one direction; An inlet is arranged on the lower end cover, a second one-way valve is arranged at the inlet, and the second one-way valve is used to make the external lubricant flow into the annular groove in one direction; The end face of the lower end cover is coaxially provided with an outlet, the lower opening of the outlet is provided with an output pipe, and the outlet is in communication with a thread processing area; A second channel is arranged in the push seat, the area between the arc surfaces of the plurality of die plates is named as a thread processing area, and the second channel is used to realize the communication between the first channel and the thread processing area.

2. The cold heading die for high-precision machining of a bolt according to claim 1, characterized by The side of the die plate away from the axis of the fixed column shell is arranged as an inclined surface one, the distance between the inclined surface one and the axis of the fixed column shell decreases from bottom to top; The side of the push seat facing the axis of the fixed column shell is arranged as an inclined surface two, the inclined surface one and the inclined surface two are attached and form a sliding connection in the inclined direction of the inclined surface one, the push seat is provided with a plurality of corresponding die plates, the upper surface of the push seat is provided with a convex rod, the upper end of the convex rod extends out of the fixed column shell, and all the convex rods are connected through a fixed ring.

3. The cold heading die for high-precision machining of a bolt according to claim 1, characterized by The upper end of the rotating shaft is provided with a slot, one end of the coil spring is connected with the upper mounting hole and the other end is inserted into the slot.

4. The cold heading die for high-precision machining of a bolt according to claim 1, characterized by The linkage comprises a spiral protrusion arranged on the hole wall of the upper mounting hole and a spiral sliding groove arranged on the outer cylindrical surface of the rotating shaft, and the spiral protrusion is located in the spiral sliding groove.

5. The cold heading die for high-precision machining of a bolt according to claim 1, characterized by The lower end of the rotating shaft is coaxially provided with a limiting ring column, the upper end of the limiting ring column and the groove bottom of the lower mounting groove are provided with a first spring, the lower end of the rotating shaft is coaxially provided with a spline groove, the spline groove is provided with a plug shaft, the lower end of the plug shaft is provided with a shape matched with the inner hexagonal hole of the blank bolt head; The blank is sent into the fixed mold member, the bolt head of the blank is supported by the bracket, the lower end of the plug shaft is first inserted into the inner hexagonal hole of the bolt head of the blank during the downward movement of the outer pressing column, then the outer pressing column continues to move downward, the second spring is compressed, when the compression amount of the second spring reaches the maximum, the lower end of the limiting ring column contacts the groove opening of the upper mounting groove, and at the same time, the lower end of the outer pressing column contacts the upper end of the fixed ring.

6. The cold heading die for high-precision machining of a bolt according to claim 5, characterized by The spline groove is provided with a plug shaft through spline, and when the plug shaft and the rotating shaft are relatively displaced, they are dynamically connected through the spline. The second spring is arranged between the plug shaft and the groove bottom of the spline groove.

7. A cold heading process for a cold heading die for high-precision machining of a bolt according to claim 5, characterized by, The method comprises the following steps: Step one: the blank is sent into the fixed mold member, the bolt head of the blank is supported by the bracket; Step two: the outer pressing column is driven to move downward, during the downward movement, the lower end of the plug shaft is first inserted into the inner hexagonal hole of the bolt head of the blank, then the outer pressing column continues to move downward, the second spring is compressed, when the compression amount of the second spring reaches the maximum, the lower end of the limiting ring column contacts the groove opening of the upper mounting groove, and at the same time, the lower end of the outer pressing column contacts the upper end of the fixed ring; Step three: the outer pressing column continues to move downward and pushes the fixed ring to move downward together, so that the tooth plate gradually closes to form a complete cylindrical outer surface, i.e. the rolling thread on the tooth plate arc surface gradually extrudes the blank, at the same time, the downward movement of the outer pressing column can make the rotating shaft rotate through the linkage, the rotating shaft rotates with the plug shaft and the blank, the blank rotates and moves downward at the same time, the thread processing is realized by gradually extruding the blank through the rolling thread and rotating and moving downward of the blank; At the same time, the push seat moves downward with the piston, so as to push the lubricant in the ring groove, the lubricant flows into the thread processing area through the connecting hole, the first one-way valve, the first channel and the second channel in turn, and the lubrication purpose is realized, the lubricated lubricant flows downward under the action of gravity, and is output outward through the outlet and the output pipe.

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