CN220760761U - Battery explosion-proof piece stamping assembling die - Google Patents

Abstract

The utility model relates to the technical field of lithium battery production and discloses a battery explosion-proof sheet stamping combined die which comprises an upper die assembly, a lower die assembly and a sheet material arranged between the upper die assembly and the lower die assembly, wherein the upper die assembly is provided with an upper die core assembly and the lower die assembly is provided with a die core assembly formed by matching the lower die core assembly, the die core assembly comprises punching die cores, trimming die cores, stretching die cores, pressure relief groove scribing die cores, appearance forming die cores and flanging blanking die cores which are arranged at intervals along the feeding direction of the sheet material, guide limit pins are arranged between the die cores, the sheet material is fed from one side, and the sheet material is pushed to the independent die cores through a pushing mechanism to prepare the required explosion-proof sheet. The problems of inaccurate processing position, different forming depth, poor quality consistency and low production efficiency of the pressure relief groove caused by the need of repositioning and transferring procedures in the prior art are solved.

Description

Battery explosion-proof piece stamping assembling die

Technical Field

The utility model relates to the technical field of lithium battery production, in particular to a battery explosion-proof piece stamping combined die.

Background

With the high-speed development of new energy, the lithium battery is widely applied due to the advantages of high energy density, long cycle life and the like; meanwhile, the safety and the reliability of the lithium battery are the technical key points of great attention, so that the lithium battery is provided with the explosion-proof piece to improve the safety performance of the lithium battery; the explosion-proof sheet is mainly characterized in that the pressure relief groove is formed in the explosion-proof sheet in a locally punching mode, when the high pressure formed in the battery reaches the threshold value of the explosion-proof sheet, the explosion-proof sheet is punched at the notch, the battery is subjected to pressure relief, and the risk of explosion of the battery is greatly reduced.

For example, chinese patent document CN208437508U discloses an outer scribing mold for an explosion-proof battery case, wherein a workpiece is pressed by cooperation of a push rod and a punch rod, and a scribing groove is stamped on the outer bottom surface of the battery case by cooperation of a forming protrusion on a scribing lower mold and the punch rod, so that when the internal pressure of the case is too high, the scribing groove on the bottom surface of the case is easily broken.

However, since the conventional battery explosion-proof sheet is of a metal sheet structure, the pressure relief groove at the bottom of the conventional battery explosion-proof sheet is usually formed by making a blank of the explosion-proof sheet, placing the blank in a simple die, and punching the pressure relief groove through a scribing die at one time; however, because the end face structure of the explosion-proof sheet is provided with errors, and equipment transfer is also involved in blanking the pressure relief groove, the pressure relief groove is often inaccurate in position, different in forming depth, poor in quality consistency and low in efficiency due to the problems of repositioning, transferring procedures and the like; therefore, the explosion-proof threshold is not reached, the explosion-proof battery is broken in advance, normal use is affected, and therefore the processing quality of the pressure relief groove is particularly important for the whole battery.

Disclosure of Invention

This application has overcome among the prior art because needs relocation and transfer process, leads to the pressure release groove processing position inaccurate, shaping depth is different, quality stability is poor and the low problem of production efficiency. In order to achieve the above object, the present application adopts the following technical solutions.

The utility model relates to a battery explosion-proof sheet stamping combined die which comprises an upper die assembly, a lower die assembly and a plate material arranged between the upper die assembly and the lower die assembly, wherein the upper die assembly is provided with an upper die core assembly and a lower die core assembly arranged on the lower die assembly to form a die core assembly in an adaptation mode, the die core assembly comprises punching die cores, trimming die cores, stretching die cores, pressure relief groove scribing die cores, appearance forming die cores and flanging blanking die cores which are arranged at intervals along the feeding direction of the plate material, guide limit pins are arranged between the die cores, and the plate material is fed from one side and pushed to the independent die cores through a pushing mechanism to obtain the required explosion-proof sheet;

the explosion-proof piece includes circular step bottom and outside turn-ups structure, circular step bottom includes the first convex part of intermediate position, sets up the second convex part in the first convex part outside and connects the first convex part and the transition portion of buckling of second convex part, be equipped with toper portion and dividing line portion between first convex part and the transition portion of buckling, dividing line portion establishes to planar structure, and is equipped with the pressure release groove on it, second convex part and the adaptation of appearance shaping mold core, pressure release groove and the adaptation of pressure release groove dividing line mold core, outside turn-ups structure and turn-ups unloading mold core.

The further improvement is that: the upper die core assembly consists of punching upper die cores, trimming upper die cores, stretching upper die cores, pressure relief groove scribing upper die cores, appearance forming upper die cores and flanging blanking upper die cores which are arranged on the upper die assembly at intervals, and the lower die core assembly consists of punching lower die cores, trimming lower die cores, stretching lower die cores, pressure relief groove scribing lower die cores, appearance forming lower die cores and flanging blanking lower die cores which are arranged on the lower die assembly and are arranged at corresponding positions of the upper die core assembly.

The further improvement is that: the pressure relief groove dividing mold core comprises an upper pressure plate, a lower pressure plate, an edge pressure plate and a pressure relief groove punch, wherein the upper pressure plate is arranged at the bottom of the pressure relief groove dividing upper mold core and presses a plate downwards, the lower pressure plate is used for pressing materials from the lower side, the edge pressure plate is arranged at the outer side of the lower pressure plate, the pressure relief groove punch is arranged between the lower pressure plate and the edge pressure plate, the upper pressure plate and the lower pressure plate are matched, and guide limiting pins are symmetrically arranged on two sides of the pressure relief groove dividing mold core.

The further improvement is that: the side surfaces of the pressure relief groove punch and the lower pressing plate are also provided with an adaptive guide limiting structure.

The further improvement is that: the shaping die core and the shaping lower die core are arranged between the stretching die core and the pressure relief groove dividing die core at intervals, and the conical surface shaping die core is arranged between the pressure relief groove dividing die core and the appearance shaping die core.

The further improvement is that: the upper die assembly comprises an upper die base and an upper base plate, the upper die base is sequentially connected with the upper base plate and the upper die core assembly, and the upper part of the upper die base is connected to the bed body support.

The further improvement is that: the upper die assembly further comprises an upper clamping plate, a stop plate and a stripper plate, wherein the upper clamping plate, the stop plate and the stripper plate are arranged below the upper base plate and penetrate through the upper die core assembly.

The further improvement is that: the lower die assembly comprises a lower die seat arranged on the bed body workbench, a lower base plate fixed on the lower die seat and a lower die plate arranged on the lower base plate, and the lower die core assembly is arranged on the lower die plate in a penetrating mode and is fixed on the lower die seat through the lower base plate.

Compared with the prior art, the utility model has the following beneficial effects:

according to the utility model, the punching die cores, the trimming die cores, the stretching die cores, the pressure relief groove scribing die cores, the profile forming die cores and the flanging blanking die cores which are arranged on the upper die assembly and the lower die assembly are in interval adaptation, the guide limiting pins are arranged between the die cores, the sheet material is fed from one side and pushed to each independent die core through the pushing mechanism, the positioning holes are punched on the sheet material and are matched with the guide limiting pins, each subsequent working procedure is ensured to be accurately positioned, the working accuracy and stability of each working procedure are ensured, the convex end face is formed through one or more shaping after stretching, the compression positioning of the pressure relief groove of the explosion-proof piece during mass production is ensured, the positioning accuracy of the pressure relief groove is ensured, the problems of time depth and time depth of the punched pressure relief groove are reduced, meanwhile, the working efficiency is further improved, the transfer between working procedures is reduced, and the production cost is reduced.

Drawings

Fig. 1 is a schematic diagram of the overall structure of the present utility model.

Fig. 2 is a schematic diagram of the overall structure of the present utility model.

Fig. 3 is a schematic view of the structure of the explosion-proof sheet manufactured by the utility model.

FIG. 4 is a partial schematic view of a pressure relief groove scoring mold core of the present utility model.

FIG. 5 is a schematic diagram of the process of the present utility model.

Fig. 6 is a schematic view of a sheet of the present utility model.

Fig. 7-10 are enlarged partial views of the plate material variation of the present utility model.

The attached drawings are identified:

the upper die assembly 1, the upper die holder 11, the upper base plate 12, the upper clamping plate 13, the stop plate 14, the stripper plate 15, the lower die assembly 2, the lower die holder 21, the lower base plate 22, the lower die plate 23, the plate 3, the positioning hole 31, the rim 32, the stretching structure 33, the shaping structure 34, the score line structure 35, the outer convex shaping structure 36, the connecting remainder 37, the explosion-proof sheet 4, the first convex part 41, the tapered part 42, the score line part 43, the pressure relief groove 44, the bending transition part 45, the second convex part 46, the flanging structure 47, the upper die assembly 5, the punching upper die core 51, the trimming upper die core 52, the stretching upper die core 53, the pressure relief groove score upper die core 55, the upper die pressing plate 551, the outline shaping upper die core 56, the flanging blanking upper die core 57, the shaping upper die core 54, the lower die core assembly 6, the punching lower die core 61, the trimming lower die core 62, the stretching lower die core 63, the pressure relief groove lower die core 65, the edge pressing plate 652, the lower die pressing plate 651, the pressure relief groove 653, the guiding limiting structure, the outline shaping lower die 66, the flanging lower die core 67, the shaping lower die core 654, the shaping lower die 8 and guiding the limiting pin 8.

Detailed Description

In order to enhance the understanding of the present utility model, the present utility model will be described in further detail with reference to the drawings, and the present embodiment is only for explaining the present utility model and is not limited to the protection scope of the present utility model.

In the description of the present utility model, it should be understood that the directions or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", etc., are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the indicated combinations or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

The utility model is described in further detail below with reference to the attached drawings and examples:

the battery explosion-proof sheet stamping combined die comprises an upper die assembly 1, a lower die assembly 2 and a plate material 3 arranged between the upper die assembly 1 and the lower die assembly 2, wherein an upper die core assembly 5 is arranged on the upper die assembly 1 and a lower die core assembly 6 arranged on the lower die assembly 2 are matched to form a die core assembly, the die core assembly comprises punching die cores, trimming die cores, stretching die cores, pressure relief groove scribing die cores, profile forming die cores and flanging blanking die cores which are arranged on the upper die assembly 1 and the lower die assembly 2 along the feeding direction of the plate material 3 at intervals, guide limit pins 8 are arranged between the die cores, the plate material 3 is fed from one side and pushed to the independent die cores through a pushing mechanism, and the required explosion-proof sheet 4 is manufactured; as shown in fig. 3: the explosion-proof sheet 4 comprises a circular step bottom and an outer flanging structure 47, the circular step bottom comprises a first convex part 41 at the middle position, a second convex part 46 arranged at the outer side of the first convex part 41 and a bending transition part 45 for connecting the first convex part 41 and the second convex part 46, a conical part 42 and a scribing part 43 are arranged between the first convex part 41 and the bending transition part 45, the scribing part 43 is of a planar structure, a pressure relief groove 44 is arranged on the scribing part 43, the second convex part 46 is matched with an outline forming mold core, the pressure relief groove 44 is formed by matching a pressure relief groove scribing mold core, and the outer flanging structure 47 is matched with a flanging blanking mold core to form the explosion-proof sheet 4;

the upper die core assembly 5 is of a male die core structure, the lower die core assembly 6 is of a female die core structure, the sheet 3 is placed between the die cores between the upper die assembly 1 and the lower die assembly 2, and the sheet 3 is punched with a positioning hole 31 through a punching die core, so that each subsequent process can be accurately positioned, and the working accuracy and stability of each process are ensured; the sheet 3 is pushed to the trimming mold core to cut the upper, lower and side edges 32, the profile of the explosion-proof sheet is punched, and meanwhile, the sheet cannot be cut, so that the normal conveying of the material belt is not influenced; in order to form the downward convex end face of the center, the center is stretched firstly, then the convex end face is formed through one or more shaping, the main purpose is to form a plane to be processed, the pressure relief groove 44 is positioned on the dividing part 43 of the plane structure, when the pressure relief groove is conveniently marked, the plate 3 enters the pressure relief groove dividing mold core to be pressed up and down, the pressure relief groove 44 is punched on the dividing part 43, so that the accurate positioning is realized, the stability of the pressure relief groove during punching is improved, the consistency of the depth of the punched pressure relief groove is ensured, and the yield of products is improved; the second convex part 46 is formed by the shape forming mold core, then the flanging blanking mold core is used for blanking and processing to form the outer flanging structure 47, and finally the required finished product of the explosion-proof sheet 4 is obtained by uninterrupted connection.

The combined stamping die adopts a continuous die structure, the punching die cores, the trimming die cores, the stretching die cores, the decompression groove scribing die cores, the appearance forming die cores and the flanging blanking die cores are arranged on the upper die assembly 1 and the lower die assembly 2 in an interval matching mode, guide limit pins 8 are arranged between the die cores, the sheet material 3 is fed from one side and pushed to the independent die cores through the pushing mechanism, the sheet material 3 is firstly punched with positioning holes 31 and the guide limit pins 8 in an matching mode, each subsequent working procedure is guaranteed, accurate positioning can be achieved, accuracy and stability of working in each working procedure are guaranteed, after stretching, an outwards protruding end face is formed through one or more shaping, compression positioning during volume production of the explosion-proof piece decompression groove is guaranteed, positioning accuracy of the decompression groove is guaranteed, depth consistency of the punched decompression groove is guaranteed, the problems of depth and time and depth of the decompression groove due to positioning are reduced, meanwhile, working efficiency is further improved, transfer among working procedures is reduced, and production cost is reduced.

More preferably: as shown in fig. 2, the upper die core assembly 5 is composed of a punching upper die core 51, a trimming upper die core 52, a stretching upper die core 53, a pressure relief groove dividing upper die core 55, an outline forming upper die core 56 and a flanging blanking upper die core 57 which are arranged on the upper die assembly 1 at intervals, and the lower die core assembly 6 is composed of a punching lower die core 61, a trimming lower die core 62, a stretching lower die core 63, a pressure relief groove dividing lower die core 65, an outline forming lower die core 66 and a flanging blanking lower die core 67 which are arranged on the lower die assembly 2 and are arranged at corresponding positions of the upper die core assembly 5; the upper die core assembly 5 moves downwards along with the upper die assembly 1 to be matched with the lower die core assembly 6 on the lower die assembly 2, and all the stamping processes are continuously completed under the pushing of the pushing mechanism. The upper die core assembly 5 and the lower die core assembly 6 are arranged on the lower die assembly 2 at intervals, so that the continuity and the synchronism of the processing of each die core of the explosion-proof sheet 4 are ensured, and the overall stability of the quality of the processed workpiece is further ensured.

More preferably: as shown in fig. 4, the pressure relief groove scribing mold core comprises an upper pressure plate 551 arranged at the bottom of the pressure relief groove scribing upper mold core 55 and pressing a plate 3 downwards, a lower pressure plate 651 pressing the plate from below, an edge pressure plate 652 arranged at the outer side of the lower pressure plate 651, and a pressure relief groove punch 653 arranged between the lower pressure plate 651 and the edge pressure plate 652, wherein the pressure relief groove pressing plate 651 and the edge pressure plate 652 are matched with the upper pressure plate 551 to press the plate 3 upwards and downwards, guide limit pins 8 are symmetrically arranged at two sides of the pressure relief groove scribing mold core, in the mold, the stretched plate 3 is positioned by the upper pressure plate 551, the edge pressure plate 652 and the lower pressure plate 651, the plate 3 can be clamped upwards and downwards and positioned completely, the pressure relief groove punch 653 is used for scribing, the pressure relief groove formed through the structure is accurate in position and high in depth consistency, the condition of shallow depth can not occur, and the stability is very good; the pressure relief groove punch 653 and the side surface of the lower pressing plate 651 are also provided with an adaptive guide limiting structure 654; the setting of the guiding limit structure 654 structurally ensures the depth quality stability of the pressure relief groove.

More preferably: the upper die assembly 1 comprises an upper die holder 11 and an upper base plate 12, the upper die holder 11 is sequentially connected with the upper base plate 12 and the upper die core assembly 5, and the upper part of the upper die holder 11 is connected to a bed body bracket; the upper die assembly 1 further comprises an upper clamping plate 13, a stop plate 14 and a stripper plate 15 which are arranged below the upper base plate 12 and penetrate through the upper die core assembly 5; the lower die assembly 2 comprises a lower die holder 21 arranged on a bed body workbench, a lower base plate 22 fixed on the lower die holder 21 and a lower die plate 23 arranged on the lower base plate 22, and the lower die core assembly 6 is arranged on the lower die plate 23 in a penetrating way and is fixed on the lower die holder 21 through the lower base plate 22. The detachable combined integral structure is firm, the mold core is convenient to maintain and replace, and the adaptability is good.

More preferred example 2: other structures are the same as those of embodiment 1, as shown in fig. 2 and 6, more than one shaping upper mold core 54 and shaping lower mold core 64 are arranged between the stretching mold core and the pressure relief groove dividing mold core at intervals, and a conical surface shaping mold core is arranged between the pressure relief groove dividing mold core and the appearance shaping mold core. The setting of plastic mold core can be according to the difficult journey of shaping structure and decide, when guaranteeing the shaping quality of work piece, still compromise whole mould subassembly blanking power, make every mold core atress even, guarantee the explosion-proof piece steady quality of making in the maximum degree, the uniformity is good.

The operation principle of the application is as follows:

as shown in fig. 1, 2 and 5-10, the sheet material 3 is pushed to each mold core by a pushing mechanism to continuously execute the following steps:

SP01 punching: firstly, a plate 3 is pushed to a punching die core through a pushing mechanism to punch, positioning holes 31 matched with guide limiting pins 8 are formed in the plate 3, and the guide limiting pins 8 are arranged at intervals for limiting corresponding position positioning holes 31 between the subsequent die cores. The accurate positioning of each subsequent process can be ensured, and the working accuracy and stability of each process are ensured;

SP02 trimming: pushing the plate 3 finished by the SP01 to a trimming mold core, and cutting the upper, lower and side edges 32 of the plate 3; the trimming can adopt two continuous trimming procedures, the outline required by the product is punched out, and the product cannot be cut at the same time, so that the normal conveying of the plate material 3 is not influenced;

SP03 stretching: pushing the cut sheet material 3 to a stretching mold core, stretching the round material at the middle part, and forming a stretching structure 33 on the middle round material of the sheet material 3;

SP04 shaping, namely pushing the stretching structure 33 on the plate 3 to one or more shaping mold cores arranged between the stretching mold cores and the pressure relief groove dividing mold cores to perform shaping, so as to obtain a shaping structure 34 integrating the first convex part 41, the dividing part 43 and the bending transition part 45 of the explosion-proof sheet 4; in order to shape the central, downwardly projecting end face, the present application forms the outwardly projecting end face shaping structure 34 by three shaping steps after stretching, which step may optionally be omitted.

Scribing a SP05 pressure relief groove: the pushing mechanism pushes the stretching structure 33 or the shaping structure 34 to the pressure relief groove scribing mold core, clamps and fully positions the plate 3 by pressing down an upper pressing plate 551 of the plate 3, a lower pressing plate 651 for pressing materials from below and an edge pressing plate 652, and then performs scribing in a mode of punching a pressure relief groove punch 653 arranged between the lower pressing plate 651 and the edge pressing plate 652 from bottom to top to form a scribing structure 35 with a pressure relief groove; after the pressure relief groove is formed, a shaping process can be added before the shaping of the outer shape, and the bottom of the stretching structure 33 or the shaping structure 34 is further shaped to form a first convex part 41, a conical part 42 and a pressure relief groove 44;

SP06 molding profile: the sheet material 3 with the score line structure 35 is pushed to a flanging blanking mold core, and the outer side of the score line structure 35 is subjected to embossing molding to form an outer convex molding structure 36 with a second convex part 46;

SP07 flanging blanking: the plate material 3 with the convex forming structure 36 is pushed to the flanging blanking mold core, and the connecting remainder 37 on the plate material 3 is punched and cut and flanging treatment is carried out on the connecting remainder, so that the required anti-explosion sheet 4 structure is finally obtained.

This stamping die's technology has guaranteed that every process all has the location, and importantly, the pressure release groove is located a plane, when conveniently marking the line, presses through upper and lower structure, improves the stability when punching press greatly, ensures that the depth of the pressure release groove that punches out is unanimous, has improved the yields of product greatly, still guarantees simultaneously under the prerequisite that current product needs, further improves work efficiency height, reduces the transfer between the process, has promoted the stability of product.

The embodiments of the present utility model are disclosed as preferred embodiments, but not limited thereto, and those skilled in the art will readily appreciate from the foregoing description that various extensions and modifications can be made without departing from the spirit of the present utility model.

Claims (8)

1. The utility model provides a battery explosion-proof piece punching press assembling die, includes last module (1), lower module (2) and sets up sheet material (3) between last module (1) and lower module (2), upward be equipped with on module (1) mould core assembly (5) and lower module (2) on lower module (6) adaptation constitution mould core assembly, its characterized in that: the die core assembly comprises punching die cores, trimming die cores, stretching die cores, pressure relief groove dividing die cores, appearance forming die cores and flanging blanking die cores which are arranged at intervals along the feeding direction of the plate (3), guide limit pins (8) are arranged between the die cores, the plate (3) is fed from one side and is pushed to the independent die cores through a pushing mechanism to prepare the required explosion-proof sheet (4);

the explosion-proof piece (4) comprises a circular step bottom and an outer flanging structure (47), the circular step bottom comprises a first convex part (41) at the middle position, a second convex part (46) arranged at the outer side of the first convex part (41) and a bending transition part (45) for connecting the first convex part (41) and the second convex part (46), a conical part (42) and a scribing part (43) are arranged between the first convex part (41) and the bending transition part (45), the scribing part (43) is arranged to be of a planar structure and is provided with a pressure relief groove (44), the second convex part (46) is matched with an outline forming mold core, the pressure relief groove (44) is matched with the pressure relief groove scribing mold core, and the outer flanging structure (47) is matched with a flanging blanking mold core.

2. The battery explosion-proof piece stamping assembling die according to claim 1, wherein: the upper die core assembly (5) is composed of punching upper die cores (51), trimming upper die cores (52), stretching upper die cores (53), pressure relief groove scribing upper die cores (55), profile forming upper die cores (56) and flanging blanking upper die cores (57) which are arranged on the upper die assembly (1) at intervals, and the lower die core assembly (6) is composed of punching lower die cores (61), trimming lower die cores (62), stretching lower die cores (63), pressure relief groove scribing lower die cores (65), profile forming lower die cores (66) and flanging blanking lower die cores (67) which are arranged on the lower die assembly (2) and are arranged at corresponding positions of the upper die core assembly (5).

3. The battery explosion-proof piece stamping assembling die according to claim 1, wherein: the pressure relief groove scribing mold core comprises an upper pressing plate (551) arranged at the bottom of a pressure relief groove scribing upper mold core (55) and used for pressing a plate material (3) downwards, a lower pressing plate (651) used for pressing materials from the lower side, an edge pressing plate (652) arranged at the outer side of the lower pressing plate (651) and a pressure relief groove punch (653) arranged between the lower pressing plate (651) and the edge pressing plate (652), wherein the upper pressing plate (551) and the lower pressing plate (3) are matched with the upper pressing plate (551) in an upper-lower mode, and guide limiting pins (8) are symmetrically arranged on two sides of the pressure relief groove scribing mold core.

4. A battery rupture disc stamping die set as set forth in claim 3, wherein: and the side surfaces of the pressure relief groove punch head (653) and the lower pressing plate (651) are also provided with an adaptive guide limiting structure (654).

5. The battery explosion-proof piece stamping assembling die according to claim 1, wherein: the shaping upper die core (54) and the shaping lower die core (64) which are matched with each other are further arranged between the stretching die core and the pressure relief groove dividing die core at intervals, and a conical surface shaping die core is arranged between the pressure relief groove dividing die core and the appearance shaping die core.

6. The battery explosion-proof piece stamping assembling die according to claim 1, wherein: the upper die assembly (1) comprises an upper die holder (11) and an upper base plate (12), the upper die holder (11) is sequentially connected with the upper base plate (12) and the upper die core assembly (5), and the upper part of the upper die holder (11) is connected to the bed body support.

7. The battery rupture disk stamping die set of claim 6, wherein: the upper die assembly (1) further comprises an upper clamping plate (13), a stop plate (14) and a stripper plate (15), wherein the upper clamping plate (13), the stop plate (14) and the stripper plate are arranged below the upper base plate (12) and penetrate through the upper die core assembly (5).

8. The battery explosion-proof piece stamping assembling die according to claim 1, wherein: the lower die assembly (2) comprises a lower die holder (21) arranged on a bed body workbench, a lower base plate (22) fixed on the lower die holder (21) and a lower die plate (23) arranged on the lower base plate (22), and the lower die core assembly (6) is arranged on the lower die plate (23) in a penetrating mode and is fixed on the lower die holder (21) through the lower base plate (22).