A cold heading forming die for bolt machining

Abstract

The present application relates to cold upsetting processing technical field, specifically to a kind of cold upsetting forming die for bolt processing, cold upsetting forming die for bolt processing includes punch and main mould, punch is used to provide cold upsetting pressure;Main mould is used as the support when bolt cold upsetting, and inside from bottom to top successively inserts and installs forming die bushing, support sleeve, sliding sleeve, top pressure block, forming die bushing is used as the die of bolt end cold upsetting forming;Multiple petal type die core structure is provided in the inside of sliding sleeve, and multiple petal type die core structure includes multiple split die core;Top pressure block is connected by guide assembly and main mould, under the action of guide assembly, top pressure block can rotate relative to main mould around its own axis, top pressure block is connected by synchronous assembly and sliding sleeve, under the action of synchronous assembly, top pressure block can synchronously drive sliding sleeve to rotate, so that top pressure block can drive multiple petal type die core structure relative to bolt rotation, so that the protrusion formed between adjacent split die core can be cut off, guarantee the surface quality of bolt.

Description

Technical Field

[0001] This invention relates to the field of cold heading technology, and in particular to a cold heading forming die for bolt processing. Background Technology

[0002] Cold heading is a typical room-temperature plastic forming process. Its core principle is to apply external force to metal wire (or coil) using a high-pressure mold, causing it to undergo plastic deformation under the mold's constraint, thereby obtaining a workpiece with a preset shape and size. This process is widely used in the mass production of fasteners such as bolts due to its advantages such as no machining required, high material utilization, and excellent workpiece mechanical properties.

[0003] In the cold heading process of bolts, a multi-station continuous processing layout is usually adopted to achieve the gradual forming from wire to finished bolt (such as head forming and shank finishing). For bolts with special structures (such as bolts with steps), the forming process must meet the dimensional accuracy and shape requirements of specific parts. Therefore, in the last cold heading station, the cold heading die is usually equipped with a multi-lobed core structure. The multi-lobed core structure includes multiple circumferentially arranged lobed cores that can slide radially. This allows the multi-lobed core structure to both contract to create a narrow neck in the final bolt and expand to facilitate the bolt's removal from the cold heading die. Related technologies, such as Chinese Patent CN110238339B, disclose a cold heading device for double-step triangular threaded bolts, which utilizes the above principle in its opening and closing die core and shell.

[0004] However, after multiple uses of the segmented mold core, since the segmented mold cores are independently set, gaps will appear on the contact surfaces of adjacent segmented mold cores due to wear. As a result, under the high pressure of cold heading, the bolt blank will be squeezed into the gap between adjacent segmented mold cores, causing a protrusion to form on the surface of the bolt blank, which affects the surface forming quality. Summary of the Invention

[0005] Therefore, it is necessary to provide a cold heading die for bolt processing to address the problem of poor surface forming quality in the current bolt cold heading process.

[0006] The above objectives are achieved through the following technical solutions:

[0007] A cold heading die for bolt processing includes a punch and a main die, which are arranged vertically, with the punch located above the main die.

[0008] Among them, the die can move in the vertical direction; a die ejector pin is vertically inserted in the die, which can move synchronously with the die in the vertical direction, slide elastically relative to the die in the vertical direction, and form a stop with the bolt head.

[0009] The main mold contains, from bottom to top, a forming mold sleeve, a support sleeve, a sliding sleeve, and an ejector block. The forming mold sleeve serves as the mold for cold heading the bolt end. A main mold ejector pin is vertically inserted inside the forming mold sleeve, capable of moving vertically and forming a stop with the bolt end. The support sleeve is fitted onto the forming mold sleeve and can slide elastically vertically. The sliding sleeve can slide synchronously with the support sleeve vertically and also rotate relative to the support sleeve around its own axis. A multi-lobed mold core structure is synchronously rotated inside the sliding sleeve. It can form a stop engagement with both the sliding sleeve and the top pressure block, and can slide vertically relative to the sliding sleeve. It includes multiple segmented die cores, which are arranged circumferentially and can all slide radially. The top pressure block can slide vertically and can form a stop engagement with the punch. It is connected to the main die through a guide component. Under the action of the guide component, the top pressure block can rotate relative to the main die around its own axis. The top pressure block is connected to the sliding sleeve through a synchronization component. Under the action of the synchronization component, the top pressure block can synchronously drive the sliding sleeve to rotate.

[0010] Furthermore, the guide assembly includes a first slide groove and a fixing protrusion. The first slide groove is formed on the inner side wall of the main mold and includes a first vertical section, an inclined section and a second vertical section. The first vertical section and the second vertical section both extend in the vertical direction and are offset in the circumferential and vertical directions. The inclined section is inclined and connected between the first vertical section and the second vertical section. The fixing protrusion is provided on the top pressure block and is slidably inserted into the first slide groove.

[0011] Furthermore, the synchronization component includes an arc groove and a guide rod. The arc groove is formed on the support sleeve, and a second sliding groove is formed on each of the two opposite sidewalls of the groove. The second sliding groove extends in the vertical direction. The guide rod is vertically set on the top pressure block and inserted into the arc groove. Two sliding protrusions are inserted into the guide rod. The two sliding protrusions are arranged opposite each other and are arranged in the radial direction of the support sleeve. They are slidably inserted into the two second sliding grooves respectively. A first elastic element is connected between the two sliding protrusions. Under the action of the first elastic element, the two sliding protrusions tend to move away from each other.

[0012] Furthermore, an adjusting seat is inserted into the inner wall of the sliding sleeve, and the adjusting seat can slide radially along the sliding sleeve; an arc groove is formed between the sliding sleeve and the adjusting seat; the arc groove has a tapered structure along its extension direction; there are multiple pairs of second sliding grooves, and the multiple pairs of second sliding grooves are arranged at intervals along the extension direction of the arc groove.

[0013] Furthermore, a second elastic element connects the ejector pin and the die, and under the action of the second elastic element, the ejector pin tends to slide downward.

[0014] Furthermore, the second elastic element is a second compression spring, which is sleeved on the ejector pin of the die.

[0015] Furthermore, a third elastic element connects the support sleeve and the main mold. Under the action of the third elastic element, the support sleeve tends to slide upward. A fourth elastic element is also inserted into the main mold. The fourth elastic element can form a stop fit with the support sleeve, and under the action of the fourth elastic element, the support sleeve tends to slide upward.

[0016] Furthermore, the third elastic element is a spring rod, which is vertically positioned.

[0017] Furthermore, the fourth elastic element is a disc spring assembly, which includes multiple disc springs stacked vertically.

[0018] Furthermore, the cold heading die for bolt processing also includes a first drive element configured to provide a driving force for the die to move vertically.

[0019] The beneficial effects of this invention are:

[0020] This invention relates to a cold heading die for bolt processing. It comprises a punch and a main die, with a forming die, a support sleeve, a sliding sleeve, and a top pressure block inserted within the main die. The sliding sleeve has a multi-lobed core structure on its inner side, and guide and synchronization components that cooperate with the top pressure block. During the cold heading process of the bolt, the rotatable nature of the sliding sleeve, top pressure block, and multi-lobed core structure, combined with the action of the guide and synchronization components, allows the top pressure block to drive the multi-lobed core structure to rotate relative to the bolt via the sliding sleeve. This shears away any protrusions formed between adjacent core lobes, thus ensuring the surface forming quality of the bolt.

[0021] Furthermore, by setting multiple pairs of adjusting seats and second sliding grooves, and setting arc grooves between the sliding sleeve and the adjusting seat, and utilizing the characteristic that the arc grooves are tapered along the extension direction, when gaps appear due to wear caused by relative sliding between the segmented mold core and the sliding sleeve, the position of the sliding protrusion is switched by rotating the top pressure block, so that the sliding protrusion and the second sliding groove closer to the small end of the arc groove cooperate, thereby ensuring that the segmented mold core and the sliding sleeve are always tightly fitted, ensuring that the adjacent segmented mold cores are always tightly fitted when the multi-segmented mold core structure shrinks, and reducing the generation of bolt surface protrusions due to loose fit. Attached Figure Description

[0022] Figure 1 A three-dimensional structural schematic diagram of a cold heading die for bolt processing provided in an embodiment of the present invention;

[0023] Figure 2 This is a front view structural schematic diagram of a cold heading forming die for bolt processing provided in an embodiment of the present invention;

[0024] Figure 3 for Figure 2 Sectional view along the AA direction;

[0025] Figure 4 A three-dimensional sectional view of a cold heading die for bolt processing provided in an embodiment of the present invention. Figure 1 ;

[0026] Figure 5 A top view of a cold heading die for bolt processing provided in an embodiment of the present invention;

[0027] Figure 6 for Figure 5 Sectional view along the BB direction;

[0028] Figure 7 for Figure 6 A magnified schematic diagram of the structure at point Y in the middle;

[0029] Figure 8 A three-dimensional sectional view of a cold heading die for bolt processing provided in an embodiment of the present invention. Figure 2 ;

[0030] Figure 9 This is a cross-sectional view of a cold heading die for bolt processing provided in an embodiment of the present invention.

[0031] Figure 10 An exploded view of a cold heading die for bolt processing provided in an embodiment of the present invention;

[0032] Figure 11 A three-dimensional structural schematic diagram of a multi-lobed core structure of a cold heading die for bolt processing provided in an embodiment of the present invention;

[0033] Figure 12 An exploded view of the multi-lobed core structure of a cold heading die for bolt processing provided in an embodiment of the present invention;

[0034] Figure 13 A three-dimensional structural schematic diagram of the sliding sleeve of a cold heading forming die for bolt processing provided in an embodiment of the present invention;

[0035] Figure 14 This is an exploded view of the sliding sleeve of a cold heading die for bolt processing provided in an embodiment of the present invention.

[0036] Figure 15 This is a three-dimensional structural diagram of the top pressure block, sliding sleeve and guide rod of the cold heading die for bolt processing provided in an embodiment of the present invention;

[0037] Figure 16 for Figure 15 A schematic diagram of the cross-sectional structure;

[0038] Figure 17 for Figure 16 A magnified schematic diagram of the structure at point Z in the middle.

[0039] in:

[0040] 1. Die; 101. Upper housing; 102. Ejector sleeve; 103. Die ejector pin; 1031. First ring; 104. Second compression spring;

[0041] 2. Main mold; 201. Lower shell; 2011. Upper end cover; 2012. Lower end cover; 202. Molding mold sleeve; 203. Support sleeve; 2031. Second ring; 2032. Third ring; 204. Sliding sleeve; 2041. Fourth ring; 2042. Protruding stop; 2043. Limiting bolt; 2044. Adjusting seat; 205. Top pressure block; 2051. Raised part; 206. Main mold ejector pin; 207. Spring rod; 208. Disc spring assembly; 209. Multi-lobed Mold core structure; 2091, segmented mold core; 20911, third slide groove; 2092, limiting pin; 2093, fourth compression spring; 210, guide assembly; 2101, first slide groove; 21011, first vertical section; 21012, inclined section; 21013, second vertical section; 2102, fixed protrusion; 211, synchronization assembly; 2111, arc groove; 21111, second slide groove; 2112, guide rod; 2113, sliding protrusion; 2114, first compression spring. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0043] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0044] In the existing cold heading process for bolts, each segmented die core 2091 is independently assembled, and adjacent segmented die cores 2091 rely solely on their assembly surfaces for sealing. During long-term, repeated synchronous contraction and expansion movements, the contact surfaces of adjacent segmented die cores 2091 gradually fail due to continuous friction and wear, creating gaps between them. Under the high pressure of cold heading, the bolt blank material, in a state of plastic deformation, seeps into these gaps due to the high-pressure extrusion. After the bolt is formed and demolded, the material that has seeped into the gaps forms excess protrusions on the bolt blank surface. These protrusions not only damage the bolt's appearance but also cause the dimensional accuracy of critical parts of the bolt to exceed allowable limits, severely affecting the bolt's forming quality and subsequent performance.

[0045] Based on this, embodiments of the present invention provide a cold heading forming die for bolt processing, which is particularly suitable for cold heading bolts with special structures (such as bolts with steps), and of course, it is also suitable for cold heading other rod-shaped workpieces with stepped structures.

[0046] Specifically, refer to Figures 1 to 17 The cold heading die for bolt processing is configured to include a punch 1 and a main die 2, which are arranged vertically, with the punch 1 located above the main die 2.

[0047] The die 1 is capable of moving vertically to facilitate the application of cold heading pressure. To facilitate the application of driving force for the vertical movement of the die 1, the cold heading die for bolt processing is configured to include a first driving component. The first driving component can be configured as a first hydraulic cylinder, which is positioned above the die 1 with its output shaft facing downwards and fixed to the top of the die 1 to facilitate the vertical movement of the die 1.

[0048] The die 1 includes an upper housing 101, which is a cylindrical structure with an open bottom. A pressure sleeve 102 is threaded into the bottom of the upper housing 101. The pressure sleeve 102 is annular. A die ejector pin 103 is vertically inserted into the die 1. The base of the die ejector pin 103 is a round rod structure. The die ejector pin 103 and the pressure sleeve 102 form a sliding fit. The ejector pin 103 can extend downward from the pressure sleeve 102 and can form a stop fit with the bolt head. A first ring 1031 is coaxially sleeved on the die ejector pin 103 near the middle. The first ring 1031 is annular and forms a sliding fit with the upper housing 101. It can also form a stop fit with the pressure sleeve 102, which helps to limit the downward sliding limit position of the die ejector pin 103. A second elastic element connects the ejector pin 103 and the die 1. Under the action of the second elastic element, the ejector pin 103 tends to slide downwards. The second elastic element can be a second compression spring 104, which is sleeved on the ejector pin 103, so that the ejector pin 103 can serve as the axial support for the second compression spring 104. The second compression spring 104 is located above the first ring 1031, and its upper and lower ends are respectively located at the inner top of the upper housing 101 and the top of the first ring 1031. Initially, under the action of the second compression spring 104, the ejector pin 103 is stopped at the top of the top pressure sleeve 102 by the first ring 1031, so that the ejector pin 103 can move synchronously with the die 1 in the vertical direction.

[0049] The main mold 2 includes a lower housing 201, which is a cylindrical structure with open top and bottom. An upper end cap 2011, which is annular, is threaded onto the top of the lower housing 201. A top pressure sleeve 102 is positioned inside the upper end cap 2011 during use and slides in contact with it. From bottom to top, the main mold 2 contains a forming mold sleeve 202, a support sleeve 203, a sliding sleeve 204, and a top pressure block 205. The forming mold sleeve 202 is vertically positioned and serves as a mold for cold-forging bolt ends. To facilitate the installation of the forming mold sleeve 202, a lower end cap 2012, which is annular, is threaded onto the bottom of the lower housing 201. The bottom end of the forming mold sleeve 202 is threaded onto the lower end cap 2012.

[0050] A main mold ejector pin 206 is vertically inserted into the forming mold sleeve 202. The main mold ejector pin 206 can move vertically and can form a stop with the end of the bolt, so that it can serve as a bottom support during cold heading of the bolt and can also push the bolt out of the main mold 2 after the bolt cold heading is completed. In order to facilitate the driving force for the main mold ejector pin 206 to move vertically, the cold heading forming mold for bolt processing is configured to also include a second driving component. The second driving component can be any one of a pneumatic cylinder, a second hydraulic cylinder, or an electric cylinder. Taking the second driving component as a second hydraulic cylinder as an example, the second hydraulic cylinder is located below the main mold 2, with the output shaft facing upward, and is fixed to the bottom of the main mold ejector pin 206, so as to drive the main mold ejector pin 206 to move vertically.

[0051] The support sleeve 203 is fitted onto the molding die sleeve 202 and can slide elastically in the vertical direction; the support sleeve 203 has a ring-shaped structure. To facilitate the elastic sliding of the support sleeve 203 in the vertical direction, a third elastic element is connected between the support sleeve 203 and the main die 2. Under the action of the third elastic element, the support sleeve 203 has a tendency to slide upward; the third elastic element can be a spring rod 207, which has a rod-shaped part and a third compression spring. The rod-shaped part is vertically arranged and located between the support sleeve 203 and the lower end cover 2012, with its upper and lower ends respectively inserted into the bottom of the support sleeve 203 and the top of the lower end cover 2012. The third compression spring is fitted onto the rod-shaped part, with its upper and lower ends respectively located at the bottom of the support sleeve 203 and the top of the lower end cover 2012. Under the action of the third compression spring, the support sleeve 203 has a tendency to slide upward. To ensure that the support sleeve 203 is subjected to uniform force, multiple spring rods 207 can be provided, and the multiple spring rods 207 are evenly arranged along the circumference of the forming mold sleeve 202.

[0052] The system is also configured to insert a fourth elastic element within the main mold 2. This fourth elastic element can form a stop engagement with the support sleeve 203, and under the action of the fourth elastic element, the support sleeve 203 tends to slide upwards. The fourth elastic element can be configured as a disc spring assembly 208, which includes multiple disc springs stacked vertically. Initially, the top of the disc spring assembly 208 and the bottom of the support sleeve 203 are spaced apart.

[0053] The sliding sleeve 204 has a ring-shaped structure and can slide vertically synchronously with the support sleeve 203, and can also rotate relative to the support sleeve 203 around its own axis. To achieve the movable connection between the sliding sleeve 204 and the support sleeve 203, a second ring 2031 is coaxially arranged on the top of the support sleeve 203, and a third ring 2032 is coaxially arranged on the inner peripheral wall of the top of the second ring 2031. A first annular groove is formed between the bottom of the third ring 2032, the inner peripheral wall of the second ring 2031, and the top of the support sleeve 203. On the outer peripheral wall of the sliding sleeve 204, a second annular groove is coaxially formed near the bottom, and a fourth ring 2041 is formed on the sliding sleeve 204. The fourth ring 2041 is rotatably inserted into the first annular groove, and the third ring 2032 is rotatably inserted into the second annular groove, so that the sliding sleeve 204 can slide vertically synchronously with the support sleeve 203, and can also rotate relative to the support sleeve 203 around its own axis.

[0054] A multi-lobed mold core structure 209 is synchronously rotated on the inner side of the sliding sleeve 204. The multi-lobed mold core structure 209 can form a stop engagement with both the sliding sleeve 204 and the top pressure block 205, and can slide vertically relative to the sliding sleeve 204. It includes multiple segmented mold cores 2091, arranged circumferentially and each capable of radial sliding. For example, if the multi-lobed mold core structure 209 includes four segmented mold cores 2091, these four segmented mold cores are arranged circumferentially along the sliding sleeve 204 and each can slide radially along the sliding sleeve 204. When the multi-lobed mold core structure 209 is fully retracted, it has a frustum shape, is vertically positioned, and is wider at the top than at the bottom, with a cylindrical through hole in the middle. Bolts pass through this through hole during use, allowing the bolt to be inserted into the multi-lobed mold core structure 209. 09. Clamping: Limiting pins 2092 and fourth compression springs 2093 are horizontally arranged between adjacent segmented mold cores 2091. The limiting pins 2092 and fourth compression springs 2093 are both perpendicular to the segmented mold cores 2091 and arranged in the vertical direction. The limiting pins 2092 are used to restrict the rotation of the segmented mold cores 2091. The fourth compression springs 2093 are in a stored state when the multi-segmented mold core structure 209 contracts, which facilitates the subsequent expansion of the multi-segmented mold core structure 209.

[0055] The inner wall of the sliding sleeve 204 is conical, wider at the top and narrower at the bottom, and forms a sliding fit with the segmented mold core 2091. When the segmented mold core 2091 slides downward relative to the sliding sleeve 204, under the conical fit, the segmented mold core 2091 moves inward, the fourth compression spring 2093 is compressed, and the multi-lobed mold core structure 209 contracts, making it easier to clamp the bolt. When the segmented mold core 2091 slides upward relative to the sliding sleeve 204, under the action of the fourth compression spring 2093, the segmented mold core 2091 moves outward, and the multi-lobed mold core structure 209 expands, making it easier to release the bolt. Four stop protrusions 2042 are provided on the bottom inner conical surface of the sliding sleeve 204. The four stop protrusions 2042 are evenly arranged in the circumferential direction and can respectively form a stop engagement with the segmented mold core 2091, which facilitates limiting the downward sliding limit position of the segmented mold core 2091 on the sliding sleeve 204, while ensuring that the multi-segment mold core structure 209 can form a stop engagement with the sliding sleeve 204.

[0056] To achieve synchronous rotation of the sliding sleeve 204 and the multi-lobed mold core structure 209, a third groove 20911 is formed between the outer conical surfaces of adjacent segmented mold cores 2091. The third groove 20911 extends along the generatrix direction of the multi-lobed mold core structure 209. Four limiting bolts 2043 are inserted into the circumferential sidewall of the sliding sleeve 204. The four limiting bolts 2043 are evenly arranged circumferentially and alternate with the stop protrusions 2042. The limiting bolts 2043 extend radially along the sliding sleeve 204 and extend inward beyond the inner conical surface of the sliding sleeve 204. The limiting bolts 2043 are slidably inserted into the third groove 20911. When the multi-lobed mold core structure 209 is fully retracted, the adjacent segmented mold cores 2091 clamp the limiting bolts 2043, enabling the sliding sleeve 204 and the multi-lobed mold core structure 209 to rotate synchronously.

[0057] The top pressure block 205 can slide vertically and forms a sliding fit with the lower housing 201. The base of the top pressure block 205 is a ring-shaped structure, horizontally positioned, with a raised portion 2051 at the bottom center. Initially, the raised portion 2051 abuts against the top of the segmented mold core 2091, forming a stop fit between the top pressure block 205 and the multi-segment mold core structure 209. The bottom end of the top pressure sleeve 102 is located below the bottom of the upper housing 101, allowing the bottom end of the top pressure sleeve 102 to abut against the top of the top pressure block 205, facilitating a stop fit between the top pressure block 205 and the die 1. During use, the bolt passes through the central through hole of the top pressure block 205. The inner diameter of the top pressure sleeve 102 is larger than the diameter of the central through hole of the top pressure block 205, creating a hole-like structure with a larger upper diameter and a smaller lower diameter between the top pressure sleeve 102 and the top pressure block 205, facilitating the placement of the bolt head.

[0058] The top pressing block 205 is connected to the main mold 2 through the guide component 210. Under the action of the guide component 210, the top pressing block 205 can rotate relative to the main mold 2 around its own axis.

[0059] Specifically, the guide component 210 is configured to include a first slide groove 2101 and a fixing protrusion 2102. The first slide groove 2101 is formed on the inner side wall of the main mold 2, specifically located on the inner peripheral wall of the lower housing 201 and near the top. The first slide groove 2101 includes a first vertical section 21011, an inclined section 21012, and a second vertical section 21013. Both the first vertical section 21011 and the second vertical section 21013 extend in the vertical direction and are staggered in the circumferential and vertical directions. The first vertical section 21011 is specifically located above the second vertical section 21013. The inclined section 21012 is inclined and connected between the first vertical section 21011 and the second vertical section 21013. The fixing protrusion 2102 is provided on the top pressing block 205, specifically located on the outer peripheral wall of the top pressing block 205, and is slidably inserted into the first slide groove 2101. Initially, the fixed protrusion 2102 is located within the first vertical section 21011. During the sliding process of the top pressing block 205, when the fixed protrusion 2102 slides within the first vertical section 21011, the top pressing block 205 only slides without rotating. When the fixed protrusion 2102 slides within the inclined section 21012, the top pressing block 205 slides and rotates simultaneously. When the fixed protrusion 2102 slides within the second vertical section 21013, the top pressing block 205 only slides without rotating.

[0060] More specifically, in order to improve the stability of the top pressing block 205 when rotating relative to the main mold 2 around its own axis, the guide component 210 is configured to include a number of equal and multiple first sliding grooves 2101 and fixed protrusions 2102. The multiple first sliding grooves 2101 are arranged circumferentially, and the multiple fixed protrusions 2102 are arranged circumferentially and are respectively slidably inserted into the multiple first sliding grooves 2101.

[0061] The top pressure block 205 is connected to the sliding sleeve 204 through the synchronization component 211. Under the action of the synchronization component 211, the top pressure block 205 can synchronously drive the sliding sleeve 204 to rotate.

[0062] Specifically, the synchronization component 211 is configured to include an arc groove 2111 and a guide rod 2112. The arc groove 2111 is formed on the support sleeve 203, specifically located at the top of the support sleeve 203, and has an arc-shaped structure. The center of the arc groove 2111 coincides with the axis of the support sleeve 203. Two second sliding grooves 21111 are formed on the two opposite sidewalls of the arc groove 2111, and the second sliding grooves 21111 extend vertically. The guide rod 2112 is vertically set on the top pressure block 205, specifically located at the bottom of the top pressure block 205, and inserted into the arc groove 2111. Two sliding protrusions 2113 are inserted into the guide rod 2112. The two sliding protrusions 2113 are arranged opposite each other and are arranged along the radial direction of the support sleeve 203, and are slidably inserted into the two second sliding grooves 21111 respectively. A first elastic element is connected between the two sliding protrusions 2113. Under the action of the first elastic element, the two sliding protrusions 2113 tend to move away from each other. The first elastic element can be set as a first compression spring 2114. When the top pressing block 205 slides, it synchronously drives the guide rod 2112 to slide; when the guide rod 2112 slides, it synchronously drives the sliding protrusion 2113 to slide along the second sliding groove 21111, avoiding motion interference. When the top pressing block 205 rotates, it synchronously drives the guide rod 2112 to rotate; when the guide rod 2112 rotates, it synchronously drives the sliding sleeve 204 to rotate through the snap-fit ​​between the sliding protrusion 2113 and the second sliding groove 21111; when the sliding sleeve 204 rotates, the adjacent segmented mold core 2091 clamps the limiting bolt 2043, so that the multi-segment mold core structure 209 can be synchronously driven to rotate.

[0063] More specifically, in order to improve the stability of the top pressure block 205 and the sliding sleeve 204 when rotating synchronously, the synchronization component 211 is configured to include an equal number of arc grooves 2111 and guide rods 2112, with the arc grooves 2111 arranged circumferentially and the guide rods 2112 arranged circumferentially.

[0064] Before cold heading, the bolt is first moved from top to bottom with its head facing upwards, so that the shank of the bolt passes through the central through hole of the top pressure block 205, and the head of the bolt stops at the top of the top pressure block 205.

[0065] During the cold heading process, the first hydraulic cylinder is activated first, and its output shaft extends, simultaneously driving the die 1 to move downwards. When the top sleeve 102 and top block 205 stop, the die ejector pin 103 and the bolt head also stop. As the die 1 continues to move downwards, under the pushing force of the top sleeve 102 and die ejector pin 103, the top block 205 and the bolt slide downwards together, and the fixing protrusion 2102 simultaneously slides downwards along the first vertical section 21011. Under the push of the top pressure block 205, the segmented mold core 2091 slides downward relative to the sliding sleeve 204. Under the cooperation of the conical surface, the segmented mold core 2091 moves inward, the fourth compression spring 2093 is compressed, and the multi-lobed mold core structure 209 contracts. When the fixed protrusion 2102 slides to the bottom end of the first vertical section 21011, the segmented mold core 2091 and the stop protrusion 2042 stop, the multi-lobed mold core structure 209 contracts completely, and clamps the shank of the bolt.

[0066] As the die 1 continues to move downward, under the pushing force of the top sleeve 102 and the die ejector pin 103, the top block 205 and the bolt continue to slide downward together. Simultaneously, the top block 205 drives the sliding sleeve 204 to slide downward through the stop engagement between the split die core 2091 and the stop protrusion 2042. Simultaneously, the sliding sleeve 204 drives the support sleeve 203 to slide downward through the insertion engagement between the first annular groove and the fourth ring 2041, and the insertion engagement between the second annular groove and the third ring 2032. The spring rod 207 is simultaneously compressed. Simultaneously, the fixed protrusion 2102 switches from the first vertical section 21011 to the inclined section 21012 and slides along the inclined section 21012, synchronously driving the top pressing block 205 to rotate. The top pressing block 205 synchronously drives the guide rod 2112 to rotate, and the guide rod 2112 synchronously drives the sliding sleeve 204 to rotate through the snap-fit ​​between the sliding protrusion 2113 and the second sliding groove 21111. Since the adjacent segmented mold core 2091 clamps the limiting bolt 2043, it can synchronously drive the multi-segment mold core structure 209 to rotate. When the fixed protrusion 2102 slides to the bottom end of the inclined section 21012, the support sleeve 203 and the disc spring assembly 208 stop, and the end of the bolt is inserted into the forming mold sleeve 202 and pushed by the main mold ejector pin 206.

[0067] As the die 1 continues to move downward, under the push of the top sleeve 102, the support sleeve 203, sliding sleeve 204, top block 205, and multi-lobed mold core structure 209 slide downward together, simultaneously compressing the first spring rod 207 and disc spring assembly 208. Simultaneously, supported by the main die ejector pin 206, the bolt end remains stationary, the die ejector pin 103 slides upward, the second compression spring 104 compresses, and simultaneously compresses the bolt downward, causing the bolt end to be formed within the forming mold sleeve 202. At this time, under the high pressure of cold heading, the bolt blank material, in a state of plastic deformation, will seep into the gap between adjacent segmented mold cores 2091 due to the high-pressure extrusion. Simultaneously, the fixing protrusion 2102 switches from the inclined section 21012 to the second vertical section 21013 and slides along the second vertical section 21013. When the fixing protrusion 2102 slides to the bottom of the second vertical section 21013, the bolt cold heading is completed.

[0068] Then the output shaft of the first hydraulic cylinder retracts, simultaneously activating the second drive cylinder. The output shaft of the second drive cylinder extends, and under the combined action of the spring rod 207 and the disc spring assembly 208, the support sleeve 203, sliding sleeve 204, top pressure block 205, multi-lobed mold core structure 209, and bolt slide upwards together, repeating the above process in reverse. When the fixed protrusion 2102 slides within the inclined section 21012, it synchronously drives the top pressure block 205 to rotate, and the top pressure block 205 synchronously drives the guide rod 2112 to rotate, and the guide rod 2112 synchronously passes through... The snap-fit ​​between the sliding protrusion 2113 and the second sliding groove 21111 drives the sliding sleeve 204 to rotate. Since the adjacent segmented mold cores 2091 clamp the limiting bolt 2043, the multi-segment mold core structure 209 can be rotated synchronously. At the same time, under the clamping of the punch ejector pin 103 and the main mold ejector pin 206, the bolt cannot rotate. Therefore, the multi-segment mold core structure 209 rotates relative to the bolt, thereby shearing off the protrusion formed between the adjacent segmented mold cores 2091, thus ensuring the surface forming quality of the bolt.

[0069] In a further embodiment, the segmented mold core 2091 is brought closer to the sliding sleeve 204 by the conical surface engagement between them. After long-term operation, the contact surface between the segmented mold core 2091 and the sliding sleeve 204 will wear due to sliding friction, which may cause the segmented mold core 2091 to be unable to fully approach each other, making it easier to generate gaps and making it easier for protrusions to form on the bolt.

[0070] Based on this, in the cold heading forming mold for bolt processing provided in the embodiment of the present invention, an adjusting seat 2044 is inserted into the inner side wall of the sliding sleeve 204, and the adjusting seat 2044 can slide radially along the sliding sleeve 204; an arc groove 2111 is formed between the sliding sleeve 204 and the adjusting seat 2044; the arc groove 2111 has a tapered structure along the extension direction; there are multiple pairs of second sliding grooves 21111, and the multiple pairs of second sliding grooves 21111 are arranged at intervals along the extension direction of the arc groove 2111.

[0071] During the cold heading process, when the contact surface between the segmented mold core 2091 and the sliding sleeve 204 is worn due to sliding friction, and the sliding protrusion 2113 slides downward along the inclined section 21012, the guide rod 2112 tends to slide along the arc groove 2111 towards the larger end. At this time, the rotational resistance of the sliding sleeve 204 is small, so that the guide rod 2112 can drive the sliding sleeve 204 to rotate synchronously through the snap-fit ​​between the sliding protrusion 2113 and the second sliding groove 21111. When the sliding protrusion 2113 slides upward along the inclined section 21012, the guide rod 2112 tends to slide towards the smaller end along the arc groove 2111. At this time, under the clamping of the die ejector pin 103 and the main die ejector pin 206, the bolt cannot rotate, resulting in a large rotational resistance of the multi-lobed mold core structure 209, which in turn results in a large rotational resistance of the sliding sleeve 204. This allows the guide rod 2112 to slide towards the smaller end along the arc groove 2111. Subsequently, through the cooperation of the sliding protrusion 2113 and the second sliding groove 21111 closer to the smaller end of the arc groove 2111, the segmented mold core 2091 and the sliding sleeve 204 are always tightly fitted, ensuring that the adjacent segmented mold cores 2091 are always tightly fitted when the multi-lobed mold core structure 209 shrinks, reducing the generation of bolt surface protrusions due to loose fit.

[0072] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A cold heading forming die for bolt working, characterized by, It includes a punch and a main die, which are arranged vertically, with the punch located above the main die; Among them, the die can move in the vertical direction; a die ejector pin is vertically inserted in the die, which can move synchronously with the die in the vertical direction, slide elastically relative to the die in the vertical direction, and form a stop with the bolt head. The main mold contains, from bottom to top, a forming mold sleeve, a support sleeve, a sliding sleeve, and an ejector block. The forming mold sleeve serves as the mold for cold heading the bolt end. The inner wall of the sliding sleeve is conical, wider at the top and narrower at the bottom. A main mold ejector pin is vertically inserted inside the forming mold sleeve, capable of moving vertically and forming a stop with the bolt end. The support sleeve is fitted onto the forming mold sleeve and can slide elastically vertically. The sliding sleeve can slide synchronously with the support sleeve vertically and also rotate relative to the support sleeve around its own axis. A multi-lobed mold core is synchronously rotated inside the sliding sleeve. The multi-lobed die core structure can form a stop engagement with both the sliding sleeve and the top pressing block, and can slide vertically relative to the sliding sleeve. It includes multiple lobed die cores arranged circumferentially, each of which can slide radially. The top pressing block can slide vertically and can form a stop engagement with the punch. It is connected to the main die through a guide component. Under the action of the guide component, the top pressing block can rotate relative to the main die around its own axis. The top pressing block is connected to the sliding sleeve through a synchronization component. Under the action of the synchronization component, the top pressing block can synchronously drive the sliding sleeve to rotate. The guiding component includes a first groove and a fixed protrusion. The first groove is formed on the inner sidewall of the main mold and includes a first vertical section, an inclined section, and a second vertical section. Both the first and second vertical sections extend vertically and are staggered in the circumferential and vertical directions. The inclined section is inclined and connects the first and second vertical sections. The fixed protrusion is set on the top pressure block and slidably inserted into the first groove. The synchronization component includes an arc groove and a guide rod. The arc groove is formed on the support sleeve, and a second groove is formed on each of the two opposite sidewalls of the arc groove. The second groove extends vertically. The guide rod is vertically set on the top pressure block and inserted into the arc groove. Two sliding protrusions are inserted into the guide rod. The two sliding protrusions are arranged opposite each other and along the radial direction of the support sleeve, and are slidably inserted into the two second grooves respectively. A first elastic element connects the two sliding protrusions. Under the action of the first elastic element, the two sliding protrusions tend to move away from each other.

2. The cold heading die for bolt processing according to claim 1, characterized in that, An adjusting seat is inserted into the inner wall of the sliding sleeve, and the adjusting seat can slide along the radial direction of the sliding sleeve; an arc groove is formed between the sliding sleeve and the adjusting seat; the arc groove has a tapered structure along its extension direction; there are multiple pairs of second sliding grooves, and the multiple pairs of second sliding grooves are arranged at intervals along the extension direction of the arc groove.

3. The cold heading die for bolt processing according to claim 1, characterized in that, A second elastic element connects the ejector pin and the die. Under the action of the second elastic element, the ejector pin tends to slide downward.

4. The cold heading die for bolt processing according to claim 3, characterized in that, The second elastic element is a second compression spring, which is sleeved on the ejector pin of the die.

5. The cold heading die for bolt processing according to claim 1, characterized in that, A third elastic element connects the support sleeve and the main mold. Under the action of the third elastic element, the support sleeve tends to slide upward. A fourth elastic element is also inserted in the main mold. The fourth elastic element can form a stop with the support sleeve, and under the action of the fourth elastic element, the support sleeve tends to slide upward.

6. The cold heading die for bolt processing according to claim 5, characterized in that, The third elastic element is a spring rod, which is set vertically.

7. The cold heading die for bolt processing according to claim 6, characterized in that, The fourth elastic element is a disc spring assembly, which includes multiple disc springs stacked vertically.

8. The cold heading die for bolt processing according to claim 1, characterized in that, The cold heading die for bolt processing also includes a first drive element configured to provide a driving force for vertical movement of the die.

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