Cold heading device for thin automobile parts

Abstract

The utility model discloses a cold heading device for thin automobile parts, which comprises a first cold heading module, a second cold heading module, a third cold heading module, a fourth cold heading module, a fifth cold heading module and a sixth cold heading module which are sequentially arranged, and the fourth cold heading module comprises a first upper die frame (1) and a first lower die frame (2) which are split. A lower extrusion face (3) is formed at the end of the first lower die frame (2), a lower positioning groove (4) is formed in the lower extrusion face (3), and a lower pressing rod (5) is fixedly connected to the middle of the first lower die frame (2). An upper extrusion face (6) is formed at the end of the first upper die frame (1), an upper positioning groove (7) is formed in the upper extrusion face (6), an upper pressing rod (8) is connected to the middle of the first upper die frame (1) in a sliding mode, and a first elastic piece (9) is connected between the upper pressing rod (8) and the first upper die frame (1). The forming stability and the machining precision of the metal cover plate during cold heading treatment can be improved.

Description

Technical Field

[0001] The utility model relates to a cold heading device, in particular to a cold heading device for thin automobile accessories. Background Art

[0002] In the processing of auto parts, cold heading process is often needed to process the bar material, so that the bar material can form a cold-headed part with a specific shape and structure after cold heading, and cooperate with subsequent processing to form a finished accessory, thereby improving the processing efficiency of auto parts and reducing its processing cost. For auto parts such as square head combination nuts and round head combination nuts, since a metal cover plate with a thickness of 1 to 2 mm will be formed at the end, the current cold heading equipment will first form a cover plate blank with a thickness of more than 2 mm at the end of the blank during processing, and then use the mold to extrude the cover plate blank from both sides, so that the cover plate blank is flattened to the specified thickness under the extrusion and expanded outward, thereby forming the corresponding cover plate structure.

[0003] However, the defect of the cold heading process is that in order to ensure the forming effect of the blank after flattening, the manufacturer needs to open a corresponding forming cavity in the middle of the mold so that the blank can completely fill the forming cavity after unfolding to achieve a metal cover of specified shape and size. However, on the one hand, the cover blank is limited by the pre-treatment process and cannot guarantee the complete accuracy of its shape, size and weight, resulting in incomplete filling or excessive overflow of the forming cavity due to the error of the metal amount during the flattening and unfolding process of the cover blank, thus affecting the forming stability and dimensional accuracy of the metal cover. On the other hand, since the fluidity of the metal decreases with the decrease of thickness, when the cover blank is expanded to the surroundings under the action of extrusion, the expansion effect of the cover blank around the four sides cannot be completely consistent, that is, there will be too much metal on one side of the cover blank to cause material accumulation, and too little metal on the other side of the cover blank cannot be fully expanded, resulting in roundness and concentricity problems of the metal cover after forming; in severe cases, some areas of the cover plate may even be unable to be unfolded in time due to excessive accumulation of material, resulting in fragmentation, reducing the yield rate of automotive parts. Moreover, due to the limitations of processing costs and equipment accuracy, it is difficult for manufacturers to ensure the forming effect of subsequent processes by improving the processing accuracy of the blanks during pre-processing.

[0004] Therefore, when processing automotive parts with metal cover plates, existing cold heading equipment will have problems of poor processing stability and low processing accuracy. Utility Model Content

[0005] The utility model aims to provide a cold heading device for thin automobile parts, which can improve the forming stability and processing accuracy of metal cover plates during cold heading treatment.

[0006] The technical solution of the utility model: a cold heading device for thin automobile parts comprises a first cold heading die set, a second cold heading die set, a third cold heading die set, a fourth cold heading die set, a fifth cold heading die set and a sixth cold heading die set which are arranged in sequence, wherein the fourth cold heading die set comprises a split first upper die frame and a first lower die frame, the end of the first lower die frame forms a lower extrusion surface, a lower positioning groove is arranged on the lower extrusion surface, and a lower pressing rod is fixedly connected to the middle of the first lower die frame; the end of the first upper die frame forms an upper extrusion surface, an upper positioning groove is arranged on the upper extrusion surface, an upper pressing rod is slidably connected to the middle of the first upper die frame, and a first elastic member is connected between the upper pressing rod and the first upper die frame;

[0007] The fourth cold heading die set extrude the cover plate blank from the upper and lower sides of the cover plate blank through the upper extrusion surface and the lower extrusion surface respectively, so that the cover plate blank is flattened and unfolded outward under the extrusion action; the lower positioning groove and the upper positioning groove are used to limit the unfolding position of the cover plate blank, so that the cover plate blank completely fills the lower positioning groove and the upper positioning groove after unfolding and overflows outward, thereby forming a step portion;

[0008] The first cold heading die set, the second cold heading die set and the third cold heading die set are used to cold heading the cylindrical accessory blank in sequence, so that the end of the accessory blank is formed into a cover plate blank around the cold heading, and the middle of the two ends of the accessory blank are respectively formed with an upper groove and a lower groove;

[0009] The fifth cold heading die set is used to punch holes in the accessory blank, thereby removing waste material between the upper groove and the lower groove and forming a through hole in the middle of the accessory blank;

[0010] The sixth cold heading die set is used to trim the cover plate blank, thereby removing the step portions around the cover plate blank.

[0011] In the aforementioned cold heading device for thin automotive accessories, a limit block slidably connected to the first upper die frame is provided on the inner side of the upper pressure rod, the inner side of the limit block is in contact with the first elastic member, and a limit step for limiting the limit block is provided in the middle of the first upper die frame; when the first upper die frame and the first lower die frame are in a fully pressed state, the lower pressure rod and the upper pressure rod respectively squeeze the upper groove and the lower groove from both ends, so that the outer ends of the upper groove and the lower groove form an oblique mouth.

[0012] In the aforementioned cold heading device for thin automotive accessories, a lower mold plate is detachably connected to the first lower mold frame, and the lower extrusion surface and the lower positioning groove are both arranged on the lower mold plate; an upper mold plate is detachably connected to the first upper mold frame, and the upper extrusion surface and the upper positioning groove are both arranged on the upper mold plate; when the first upper mold frame and the first lower mold frame are in a fully pressed state, a gap is formed between the upper mold plate and the lower mold plate for the cover plate blank to overflow outward, and the ends of the first upper mold frame and the first lower mold frame are in contact with each other.

[0013] In the aforementioned cold heading device for thin automotive parts, a first ejector rod slidably connected to the first lower die frame is provided on the outside of the lower pressure rod, and a first telescopic rod is connected to the inside of the first ejector rod. The first ejector rod is used to eject the part blank outward after the cold heading is completed.

[0014] In the aforementioned cold heading device for thin automotive accessories, the sixth cold heading die set includes a split second upper die frame and a second lower die frame, a second ejector rod is provided in the middle of the second lower die frame, one end of the second ejector rod is connected to the discharge portion, the other end of the second ejector rod is provided with a first protrusion for snap-fitting and connecting the accessory blank, one side of the second ejector rod is connected to the limiting sleeve via a second elastic member, and the second ejector rod and the limiting sleeve are nested inside and outside; a positioning rod is provided in the middle of the second upper die frame, the inner end of the positioning rod is connected to the second upper die frame via a third elastic member, a cutting block detachably connected to the second upper die frame is provided on the outer side of the positioning rod, the positioning rod and the cutting block are nested inside and outside and slidably connected, the positioning rod passes through the cutting block and extends to the outer side of the second upper die frame, and the end of the positioning rod is provided with a second protrusion for snap-fitting and connecting the accessory blank.

[0015] Compared with the prior art, the utility model has the following characteristics:

[0016] (1) The utility model uses the structural coordination of the fourth cold heading die set and the sixth cold heading die set to first cold head the cover plate blank to form a step portion during the processing, and then cut off the step portion to obtain a finished cover plate, so that the amount of metal in the cover plate blank before unfolding can exceed the amount of metal required for the finished cover plate, that is, to ensure that the upper positioning groove and the lower positioning groove can be completely filled after the cover plate blank is unfolded, avoiding the situation where the cover plate blank cannot be completely formed due to metal amount or uniformity problems, and reducing the manufacturer's requirements for the pre-processing accuracy of the accessory blank; the step portion formed after the cover plate blank overflows can be cut off through a subsequent cold heading process, so that cover plate blanks with different metal amounts can form metal cover plates of specified external dimensions after processing, effectively improving the dimensional accuracy of the metal cover plate after processing;

[0017] (2) By forming a step portion after the cover plate blank overflows, on the one hand, the stability of the cover plate blank during cold heading can be improved, and the cover plate blank can be prevented from being broken due to excessive accumulation of material in the positioning groove. On the other hand, the edge defects of the cover plate blank caused by uniformity problems during the cold heading process can be transferred to the step portion, thereby ensuring the dimensional accuracy of the cover plate blank after trimming. After the positioning groove is set, it can provide an obstacle to the overflow of metal, so that the metal can more fully fill the edge of the positioning groove during the flow process, that is, to ensure the forming effect of the metal cover plate at the edge position;

[0018] (3) By defining the structure of the lower pressure rod and the upper pressure rod in the fourth cold heading die set, the lower pressure rod and the upper pressure rod can extrude the two ends of the blank to form a bevel during the cold heading process; by defining the structure of the sixth cold heading die set, on the one hand, the bevel can be used to position the blank during cold heading, so that the blank can be processed with the bevel as the positioning surface during the two cold heading processes, thereby improving the processing accuracy of the accessory blank; on the other hand, by clamping the bevels at both ends of the blank during the cold heading process, the cover plate blank can also adjust its own flatness and verticality with the inner hole of the blank during the cold heading process, thereby further improving the processing accuracy of the automotive parts;

[0019] (4) Through the structural coordination of the limiting sleeve, the second elastic member and the second ejector rod, the second ejector rod can be in a fixed state during the cold heading process of the sixth cold heading die set and provide support for the limiting sleeve, so that the limiting sleeve can support and shrink the blank inward under the action of the second elastic member; when the sixth cold heading die set completes the cold heading work, the second ejector rod can be ejected outward under the action of the discharge part, and then drive the limiting sleeve to eject the cover plate, thereby realizing the automatic blanking of the finished accessories;

[0020] Therefore, the utility model can improve the forming stability and processing accuracy of the metal cover plate during cold heading treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the fourth cold heading module;

[0022] Figure 2 yes Figure 1 A-direction enlarged view;

[0023] Figure 3 It is a structural schematic diagram of the sixth cold heading die set in a fully pressed state;

[0024] Figure 4 yes Figure 3 B-direction enlarged view;

[0025] Figure 5 It is a structural schematic diagram of the sixth cold heading module in the discharging state;

[0026] Figure 6 It is a process flow chart of the utility model;

[0027] Figure 7 It is the process flow chart of existing automobile accessories.

[0028] The markings in the accompanying drawings are: 1-first upper mold frame, 2-first lower mold frame, 3-lower extrusion surface, 4-lower positioning groove, 5-lower pressure rod, 6-upper extrusion surface, 7-upper positioning groove, 8-upper pressure rod, 9-first elastic member, 10-limiting block, 11-limiting step, 12-lower template, 13-upper template, 14-first ejector rod, 15-first telescopic rod, 16-second upper mold frame, 17-second lower mold frame, 18-second ejector rod, 19-discharging part, 20-first protrusion, 21-second elastic member, 22-limiting sleeve, 23-calibration rod, 24-third elastic member, 25-cutting block, 26-second protrusion, 27-retaining ring, 100-upper groove, 200-lower groove, 300-bevel. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0030] Embodiment. A cold heading device for thin automobile parts is composed of Figure 1-5 As shown, it includes a first cold heading die set, a second cold heading die set, a third cold heading die set, a fourth cold heading die set, a fifth cold heading die set and a sixth cold heading die set which are arranged in sequence, wherein the first cold heading die set, the second cold heading die set, the third cold heading die set and the fifth cold heading die set are all conventional cold heading die sets used for automobile parts, and the blank is processed according to conventional processes;

[0031] The first cold heading die set, the second cold heading die set and the third cold heading die set are used to cold heading the cylindrical accessory blank in sequence, so that the end of the accessory blank is formed into a cover plate blank after cold heading, and the middle of the two ends of the accessory blank are respectively formed with an upper groove 100 and a lower groove 200;

[0032] The fourth cold heading die set comprises a split first upper die frame 1 and a first lower die frame 2, the end of the first lower die frame 2 forms a lower extrusion surface 3, the lower extrusion surface 3 is provided with a lower positioning groove 4, and the middle part of the first lower die frame 2 is fixedly connected with a lower pressing rod 5; the end of the first upper die frame 1 forms an upper extrusion surface 6, the upper extrusion surface 6 is provided with an upper positioning groove 7, the middle part of the first upper die frame 1 is slidably connected with an upper pressing rod 8, and a first elastic member 9 is connected between the upper pressing rod 8 and the first upper die frame 1; the fourth cold heading die set extrude the cover plate blank from the upper and lower sides of the cover plate blank through the upper extrusion surface 6 and the lower extrusion surface 3 respectively, so that the cover plate blank is flattened and expanded outward under the extrusion action; the lower positioning groove 4 and the upper positioning groove 7 are used to limit the expansion position of the cover plate blank, so that the cover plate blank completely fills the lower positioning groove 4 and the upper positioning groove 7 after expansion and overflows outward, thereby forming a step portion, and step grooves are formed on the upper and lower sides of the step portion;

[0033] The fifth cold heading die set is used to punch holes in the accessory blank, thereby removing the waste material between the upper groove 100 and the lower groove 200 and forming a through hole in the middle of the accessory blank;

[0034] The sixth cold heading die set is used to trim the cover plate blank, thereby removing the step portions around the cover plate blank.

[0035] The inner side of the upper pressure rod 8 is provided with a limit block 10 which is slidably connected to the first upper mold frame 1, the inner side of the limit block 10 is in contact with the first elastic member 9, and the middle part of the first upper mold frame 1 is provided with a limit step 11 for limiting the limit block 10; when the first upper mold frame 1 and the first lower mold frame 2 are in a fully pressed state, the lower pressure rod 5 and the upper pressure rod 8 squeeze the upper groove 100 and the lower groove 200 from both ends respectively, so that the outer ends of the upper groove 100 and the lower groove 200 form an oblique opening 300.

[0036] The first lower mold frame 2 is detachably connected to a lower mold plate 12, and the lower extrusion surface 3 and the lower positioning groove 4 are both arranged on the lower mold plate 12; the first upper mold frame 1 is detachably connected to an upper mold plate 13, and the inner end of the upper mold plate 13 is used to limit the upper pressure rod 8, and the upper extrusion surface 6 and the upper positioning groove 7 are both arranged on the upper mold plate 13; when the first upper mold frame 1 and the first lower mold frame 2 are in a fully pressed state, a gap is formed between the upper mold plate 13 and the lower mold plate 12 for the cover plate blank to overflow outward, and the ends of the first upper mold frame 1 and the first lower mold frame 2 are fitted with each other.

[0037] The outside of the lower pressing rod 5 is provided with a first ejector rod 14 slidably connected to the first lower die frame 2, and the inner side of the first ejector rod 14 is connected to a first telescopic rod 15. The first ejector rod 14 is used to eject the accessory blank outward after the cold heading is completed.

[0038] The sixth cold heading die set includes a split second upper die frame 16 and a second lower die frame 17, a second ejector rod 18 is provided in the middle of the second lower die frame 17, one end of the second ejector rod 18 is connected to a discharge portion 19, the other end of the second ejector rod 18 is provided with a first protrusion 20 for snap-fitting and connecting the accessory blank, one side of the second ejector rod 18 is connected to a limiting sleeve 22 via a second elastic member 21, and the second ejector rod 18 and the limiting sleeve 22 are nested inside and outside; a calibration rod 23 is provided in the middle of the second upper die frame 16, the inner end of the calibration rod 23 is connected to the second upper die frame 16 via a third elastic member 24, a cut block 25 detachably connected to the second upper die frame 16 is provided on the outer side of the calibration rod 23, the calibration rod 23 and the cut block 25 are nested inside and outside and slidably connected, the calibration rod 23 passes through the cut block 25 and extends to the outer side of the second upper die frame 16, and the end of the calibration rod 23 is provided with a second protrusion 26 for snap-fitting and connecting the accessory blank.

[0039] The outer side of the cutting block 25 is sleeved with a retaining ring 27 in a fixed position.

[0040] The working principle of the utility model: when in use, the first cold heading die set, the second cold heading die set and the third cold heading die set perform cold heading treatment on the raw material for multiple times in sequence, so that the raw material is formed into a fitting blank of a specified shape after cold heading. After the fitting blank is formed, the fitting blank is buckled and mounted on the lower template 12 by a clamp, and the cover blank is located in the lower positioning groove 4. After the fitting blank is placed, the first upper die frame 1 and the upper pressing rod 8 are pressed down together, and the upper pressing rod 8 is buckled in the upper groove 100 after being pressed down. At this time, the upper pressing rod 8 will be hindered by the fitting blank and cannot continue to be pressed down, so that the downward pressing action of the first upper die frame 1 will cause the limit block 10 to shrink inward, and the upper pressing rod 8 maintains this height state unchanged. When the limit block 10 shrinks inward to fit the limit step 11, the upper pressure rod 8 is in a fully retracted state. After the first upper mold frame 1 continues to press down, it will apply a hard extrusion force to the accessory blank through the upper pressure rod 8, and cooperate with the lower pressure rod 5 below to punch the two ends of the accessory blank, thereby forming an oblique opening 300. At the same time, the upper template 13 and the lower template 12 squeeze the cover blank from the upper and lower sides after pressing down, so that the cover blank is flattened and expanded to the surroundings under the extrusion. When the cover blank completely fills the lower positioning groove 4 and the upper positioning groove 7 after expansion, the excess blank will overflow from the gap between the upper template 13 and the lower template 12, forming a step portion.

[0041] When the first upper die frame 1 is pressed down to fit the first lower die frame 2, the fourth cold heading die set completes the pressing action, and then the first upper die frame 1 rises and resets, and the first telescopic rod 15 drives the first ejector rod 14 to eject the accessory blank, so that the accessory blank is clamped by the clamp and sent to the fifth cold heading die set for processing.

[0042] After the fifth cold heading die set cold-forging the inner hole of the accessory blank, the fixture clamps the accessory blank and buckles it in the limiting sleeve 22, and then the second upper die frame 16 presses down to make the calibration rod 23 buckle in the oblique opening 300 at the upper end of the accessory blank. After the calibration rod 23 is buckled, the second upper die frame 16 continues to press down, and presses the accessory blank into the second lower die frame 17 through the cut block 25, and makes it shrink inward together with the limiting sleeve 22, while the step portion around the cover blank is blocked by the second lower die frame 17 and forms shear between the cover blank, thereby realizing the trimming function, and the step portion is cut off and then sleeved on the outside of the cut block 25. By setting the step groove, the shear resistance of the cover blank at the step position can be effectively reduced, so that the step portion can be smoothly cut under the shearing action, that is, the trimming effect of the accessory blank is improved.

[0043] After the accessory blank is squeezed and moved inward by the alignment rod 23 and the cut block 25, it is then engaged with the first protrusion 20 at the end of the second ejector rod 18, so that the accessory blank is positioned from both ends by the cooperation of the second ejector rod 18 and the alignment rod 23, so that the accessory blank is kept coaxial with the second ejector rod 18 and the alignment rod 23 in this state. After the cut block 25 is pressed down, the limiting sleeve 22 shrinks inward to fit with the second lower die frame 17, that is, reaches a low position, and then cooperates with the subsequent downward pressing action of the cut block 25 to flatten the cover plate blank from both sides, so that the cover plate blank is in a mutually perpendicular state with the inner hole of the accessory blank under the extrusion action, that is, the shape correction of the cover plate blank is achieved.

[0044] When the sixth cold heading die set completes the cold heading action, the second upper die frame 16 rises and resets, and then the discharge portion 19 is ejected and drives the second ejector rod 18 to extend outward; after being ejected, the second ejector rod 18 drives the limiting sleeve 22 to be ejected together through the second elastic member 21, so that the cover plate at the end of the accessory is ejected to the outside of the second lower die frame 17, thereby realizing the discharge of the accessory. After the cut block 25 rises to its position, the step portion sleeved on the outside of the cut block 25 is intercepted by the retaining ring 27 and separated from the cut block 25, thereby realizing the separation and blanking of the step portion.

[0045] To facilitate the description of the process flow, the above description is based on the fourth cold heading module and the sixth cold heading module in a vertical state. When the forming device is actually installed and used, each cold heading module can be placed horizontally and the forming function can be realized in the same way.

Claims

1. Cold heading device for thin automobile parts, characterized by: The invention comprises a first cold heading die set, a second cold heading die set, a third cold heading die set, a fourth cold heading die set, a fifth cold heading die set and a sixth cold heading die set which are arranged in sequence. The fourth cold heading die set comprises a split first upper die frame (1) and a first lower die frame (2). The end of the first lower die frame (2) forms a lower extrusion surface (3), and a lower positioning groove (4) is provided on the lower extrusion surface (3). A lower pressing rod (5) is fixedly connected to the middle of the first lower die frame (2); an upper extrusion surface (6) is formed at the end of the first upper die frame (1), and an upper positioning groove (7) is provided on the upper extrusion surface (6). An upper pressing rod (8) is slidably connected to the middle of the first upper die frame (1), and a first elastic member (9) is connected between the upper pressing rod (8) and the first upper die frame (1); The first cold heading die set, the second cold heading die set and the third cold heading die set are used to sequentially cold head the cylindrical accessory blank, so that the end of the accessory blank is formed into a cover plate blank around the cold head, and an upper groove (100) and a lower groove (200) are respectively formed in the middle of the two ends of the accessory blank; The fourth cold heading die set extrude the cover plate blank from the upper and lower sides of the cover plate blank respectively through the upper extrusion surface (6) and the lower extrusion surface (3), so that the cover plate blank is flattened and unfolded outwards under the extrusion action; the lower positioning groove (4) and the upper positioning groove (7) are used to limit the unfolding position of the cover plate blank, so that the cover plate blank completely fills the lower positioning groove (4) and the upper positioning groove (7) after unfolding and overflows outwards, thereby forming a step portion; The fifth cold heading die set is used to punch holes in the accessory blank, thereby removing waste material between the upper groove (100) and the lower groove (200) and forming a through hole in the middle of the accessory blank; The sixth cold heading die set is used to trim the cover plate blank, thereby removing the step portions around the cover plate blank.

2. The cold heading device for thin automobile parts according to claim 1, characterized in that: A limit block (10) slidably connected to the first upper mold frame (1) is provided on the inner side of the upper pressure rod (8); the inner side of the limit block (10) is in contact with the first elastic member (9); a limit step (11) for limiting the limit block (10) is provided in the middle of the first upper mold frame (1); when the first upper mold frame (1) and the first lower mold frame (2) are in a fully pressed state, the lower pressure rod (5) and the upper pressure rod (8) respectively squeeze the upper groove (100) and the lower groove (200) from both ends, so that the outer ends of the upper groove (100) and the lower groove (200) form an oblique opening (300).

3. The cold heading device for thin automobile parts according to claim 1, characterized in that: The first lower mold frame (2) is detachably connected to a lower mold plate (12), and the lower extrusion surface (3) and the lower positioning groove (4) are both arranged on the lower mold plate (12); the first upper mold frame (1) is detachably connected to an upper mold plate (13), and the upper extrusion surface (6) and the upper positioning groove (7) are both arranged on the upper mold plate (13); when the first upper mold frame (1) and the first lower mold frame (2) are in a fully pressed state, a gap is formed between the upper mold plate (13) and the lower mold plate (12) for the cover blank to overflow outward, and the ends of the first upper mold frame (1) and the first lower mold frame (2) are in contact with each other.

4. The cold heading device for thin automobile parts according to claim 1, characterized in that: The outside of the lower pressing rod (5) is provided with a first ejector rod (14) slidably connected to the first lower die frame (2), and the inside of the first ejector rod (14) is connected to a first telescopic rod (15). The first ejector rod (14) is used to eject the accessory blank outward after the cold heading is completed.

5. The cold heading device for thin automobile parts according to claim 1, characterized in that: The sixth cold heading die set comprises a split second upper die frame (16) and a second lower die frame (17); a second ejector rod (18) is provided in the middle of the second lower die frame (17); one end of the second ejector rod (18) is connected to a discharge portion (19); the other end of the second ejector rod (18) is provided with a first protrusion (20) for snap-fitting and connecting with the accessory blank; one side of the second ejector rod (18) is connected to a limiting sleeve (22) via a second elastic member (21); the second ejector rod (18) and the limiting sleeve (22) are nested inside and outside; A calibration rod (23) is provided in the middle of the second upper die frame (16); the inner end of the calibration rod (23) is connected to the second upper die frame (16) via a third elastic member (24); a cut block (25) detachably connected to the second upper die frame (16) is provided on the outer side of the calibration rod (23); the calibration rod (23) and the cut block (25) are nested inside and outside and slidably connected; the calibration rod (23) passes through the cut block (25) and extends to the outer side of the second upper die frame (16); and a second protrusion (26) for buckling and connecting the accessory blank is provided at the end of the calibration rod (23).

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