CN108043959A - A kind of thermal forming device - Google Patents

Abstract

The invention relates to the field of mechanical processing, in particular to a thermoforming device. The device includes a first base plate, a second base plate, and a plurality of molds arranged between the first base plate and the second base plate, each mold includes an upper mold and a lower mold that cooperate with each other, and the upper mold includes an upper mold base and an upper mold body , the lower mold includes a lower mold base and a lower mold body, the upper mold base is installed on the first substrate, the top of the upper mold body is connected with the upper mold base, the lower mold base is installed on the second base plate, and the bottom of the lower mold body is connected to the lower mold body. The mold bases are connected, and a mold cavity for accommodating workpieces is formed between the bottom of the upper mold body and the top of the lower mold body; the upper mold body or the lower mold body has movable parts, and the movable parts are used to change the size of the mold cavity, so that each The contact pressure between the surface of the cavity of the mold and the surface of the corresponding workpiece tends to be consistent. The invention can improve the production efficiency and product yield rate of processing multiple workpieces at the same time.

Description

A thermoforming device

technical field

The invention relates to the field of mechanical processing, in particular to a thermoforming device.

Background technique

Mold, various molds and tools used in industrial production for injection molding, blow molding, extrusion, die-casting or forging forming, smelting, stamping and other methods to obtain the required products. In short, a mold is a tool used to shape an article. This tool is composed of various parts, and different molds are composed of different parts. It mainly realizes the processing of the shape of the article through the change of the physical state of the formed material.

At present, the thermoforming molds used by major hot stamping parts suppliers are all produced by multi-material pieces, and generally adopt the form of one mold with multiple cavities or multi-mode joint installation. The structure of a multi-cavity thermoforming mold is shown in Figure 1, and the structure of a multi-mode thermoforming mold is shown in Figure 2.

The gap between the punch and the die in the hot stamping die has a much higher impact on the production efficiency of the part than the cold stamping die. Quenching is the most important part of thermoforming. It is not only the most critical point to determine the efficiency of thermoforming, but also the decisive point for the success or failure of thermoforming! The heat transfer coefficient during quenching is affected by the contact pressure, as shown in Figure 3, the higher the pressure, the larger the heat transfer coefficient, and the smaller the pressure, the smaller the heat transfer coefficient. At the same time, when the contact pressure is lower than 0pa, the heat transfer coefficient will increase with The increase in the gap between the tablet and the mold further reduces it.

In the hot stamping process, the thickness of the sheet is not absolutely consistent, and there will be a tolerance of ±0.05mm. This tolerance will bring the following results: the lower limit of the negative tolerance is -0.05mm with the thickness of the sheet A and sheet D , the material thickness of sheet B and sheet C is positive tolerance and the upper line is +0.05mm as an example, this deviation is within the tolerance range, and it is a qualified sheet. The result of the influence of this deviation is: when the tablet B and the tablet C are in contact with the convex and concave molds in the cavity, the gap between the tablet A and the tablet D and the concave mold in the cavity is 0.1mm . This has a great impact on the thermoforming efficiency. As shown in the graph in Figure 3 above, this gap leads to a difference in the thermal conductivity between the sheet and the mold cavity by several times, which also brings a series of problems.

At the same time, there are also tolerances for the dimensions in the height direction of the jointly installed molds. And this tolerance will be larger than the sheet thickness tolerance, and it will also cause incomplete fit between the sheet and the cavity.

In Figure 4, in theory, the four sets of molds share the force of the press together, but due to the influence of tolerances, the pressure exerted by the mold on the sheet metal with positive tolerance becomes greater than the theoretical value, while the sheet metal with negative tolerance and There is a certain gap between the molds. The direct impact of this result is that the cooling rate of the sheet with positive tolerance is several times that of the sheet with negative tolerance, which in turn brings the following problems:

1. The production efficiency is limited, and the production cycle is limited by the cooling time of the slowest cooling plate.

2. The yield rate is low, and the slow cooling rate of the sheet metal will inevitably cause incomplete transformation of martensite, thus making the overall strength of the part uneven and affecting the tensile strength of the part.

3. Part of the insert of the punch is damaged. When the slowest-cooling sheet can meet the strength conditions for demoulding, the fast-cooling sheet will "tightly" hold the punch because of its low temperature and thermal expansion. The 1500MPa hot-formed steel plate is easy to pull out the punch insert and damage the mold, shortening the service life of the mold. When the damage reaches a certain level, the insert needs to be replaced, which increases the production cost.

From the above analysis, it can be seen that there are many defects in the existing hot stamping dies, and it is urgent to optimize their structures.

Contents of the invention

In view of the above-mentioned problems in the prior art, the purpose of the present invention is to provide a thermoforming mold that can make the sheets in each cavity fit closely with the inside of the cavity, which can improve production efficiency and product yield.

In order to solve the above problems, a thermoforming device of the present invention includes a first base plate, a second base plate, and a plurality of molds arranged between the first base plate and the second base plate,

Each mold includes an upper mold and a lower mold that cooperate with each other, the upper mold includes an upper mold base and an upper mold body, the lower mold includes a lower mold base and a lower mold body, and the upper mold base is installed on the first On the substrate, the top of the upper mold body is connected to the upper mold base, the lower mold base is installed on the second substrate, the bottom of the lower mold body is connected to the lower mold base, and the upper mold base is connected to the lower mold base. A mold cavity for accommodating workpieces is formed between the bottom of the mold body and the top of the lower mold body;

The upper mold body or the lower mold body has movable parts, and the movable parts are used to change the size of the mold cavity, so that the contact between the surface of the mold cavity of each mold in the device and the surface of the corresponding workpiece The pressure tends to be consistent.

Preferably, the upper mold body is fixedly connected to the upper mold base, and the lower mold body has movable parts;

The upper mold body is a die, the upper mold body includes a second insert and a binder core, the binder core is installed on the upper mold base, and the second insert is located outside the binder core , the second insert is fixed to the upper mold base, and the bottom surface of the binder core is higher than the bottom surface of the second insert;

The lower die body is a convex die, and the lower die body includes a blank holder, a first connecting piece and a first insert, the first insert is the movable part, and the binder ring is located on the first insert. The outer side of the block, the top surface of the binder ring is opposite to the bottom surface of the binder core, the binder ring is fixedly connected to the lower mold base, the top surface of the first insert is connected to the binder core The bottom surface of the core is opposite, and the first insert is connected to the lower mold base through the first connecting piece, and the first connecting piece can provide a floating top for the first insert facing the binder core. Material strength.

Preferably, the lower mold base has a first support, the first support is located outside the first connecting piece, and the blank holder is connected to the lower mold base through the first support; The first connecting member is a hydraulic cylinder, the lower end of the first insert is connected with the piston rod of the hydraulic cylinder, and the cylinder body of the hydraulic cylinder is connected with the lower mold base.

Preferably, the lower mold further includes a lower mold guide, the lower mold guide is arranged between the lower mold base and the blank holder, and is located outside the first support; the upper The mold also includes an upper mold guide, and the upper mold guide is arranged between the upper mold base and the blank holder, and is located outside the second insert.

Preferably, a first guide plate is further provided between the outer wall of the first insert and the inner wall of the first support.

Preferably, the lower mold body is fixedly connected to the lower mold base, and the upper mold body has movable parts;

The lower die body is a convex die, the lower die body includes a fourth insert, the fourth insert is fixed to the lower die base, and the top surface of the fourth insert has a protrusion;

The upper mold body is a die, the upper mold body includes a fifth insert and a second connecting piece, the fifth insert is the movable part, and the fifth insert is connected to the second connecting piece through the second connecting piece. The upper mold base is connected, the fifth insert is opposite to the fourth insert, the bottom surface of the fifth insert has a concave structure that matches the fourth insert, and the second connecting piece can be The fifth insert provides a floating ejection force toward the fourth insert.

Preferably, the second connecting member is a hydraulic cylinder, the upper end of the fifth insert is connected to the piston rod of the hydraulic cylinder, and the cylinder body of the hydraulic cylinder is connected to the upper mold base.

Preferably, the upper mold base has a recessed accommodation groove, the second connecting piece is fixed in the accommodation groove, and the outer periphery of the fifth insert is provided with a boss, and the boss accommodates in the accommodating tank.

Preferably, the upper mold body further includes a limiting plate, one end of the limiting plate is connected to the edge of the accommodating groove, the other end of the limiting plate partially covers the opening of the accommodating groove, and the fifth inlay The boss of the block is located above the limiting plate, and the limiting plate can support the boss so as to prevent the fifth insert from breaking away from the accommodating groove.

Preferably, the upper mold body further includes a second guide plate, and the second guide plate is located between the inner wall of the accommodating groove and the outer wall of the fifth insert.

A thermoforming device of the present invention has the following beneficial effects:

The invention designs movable parts for the mould, through which the size of the mold cavity is adaptively adjusted according to the material of the workpiece, so that the contact pressure between the surface of the workpiece and the mold tends to be consistent, thereby eliminating various tolerances and accumulated tolerances The resulting deviation makes the cooling rates of different sheets tend to be consistent from the root, so that the workpieces produced by multi-cavities can be cooled under the same conditions to achieve the best production efficiency. In addition, since the cooling rate of the workpiece tends to be consistent, it can ensure the formation of complete martensite, ensure that all parts of the workpiece have consistent tensile strength, and improve product yield.

The design of the movable parts of the present invention enables the mold to be adapted to different presses. At the same time, it avoids the thermal expansion caused by the different cooling rates, which causes the workpiece to be embedded in the punch, thereby causing damage to the insert and prolonging the service life of the mold.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the following will briefly introduce the drawings required for the embodiments or the description of the prior art. Apparently, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings according to these drawings without any creative work.

Fig. 1 is the structural representation of existing one mold multi-cavity thermoforming device;

Fig. 2 is the structural representation of the thermoforming device of existing multi-mode joint installation;

Fig. 3 is a relationship diagram between factors influencing thermoforming efficiency and heat transfer coefficient;

Fig. 4 is the schematic diagram that utilizes existing thermoforming device to process parts;

Fig. 5 is a schematic structural view of a thermoforming device provided by Embodiment 1 of the present invention;

Fig. 6 is a schematic structural view of a thermoforming mold provided by Embodiment 1 of the present invention;

Fig. 7 is a schematic structural diagram of a thermoforming device provided by Embodiment 2 of the present invention;

Fig. 8 is a schematic structural view of a thermoforming mold provided by Embodiment 2 of the present invention.

In the figure: 1-first base plate, 2-mold, 3-second base plate, 21-upper die, 22-workpiece, 23-lower die, 211-upper die seat, 213-pressure material core, 214-upper die guide Components, 215-second insert, 231-lower mold seat, 232-first connecting piece, 233-first insert, 234-lower mold guide, 235-first guide plate, 236-binder ring, 216- The fifth insert, 217 - the second connecting piece, 218 - the second guide piece, 219 - the limit plate, 238 - the fourth insert.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiment one

This embodiment provides a thermoforming device. As shown in FIG. 5 , the device 2 includes a first substrate 1 , a second substrate 3 and a plurality of molds 2 arranged between the first substrate 1 and the second substrate 3 . Referring to Fig. 6, each mold 2 comprises an upper die 21 and a lower die 23 that cooperate with each other. , the upper mold base 211 is installed on the first substrate 1, the top of the upper mold 21 body is connected to the upper mold base 211, and the lower mold base 231 is installed on the second base plate 3, The bottom of described lower mold body is connected with described lower mold base 231, and the die cavity that accommodates workpiece 22 is formed between the bottom of described upper mold 21 body and the top of described lower mold 23 body; Above-mentioned upper mold base 211 is fixedly connected, and described lower mold body has movable part, and described movable part is used for changing the size of described mold cavity, makes the surface of the mold cavity of each mold in the described device and the surface of corresponding workpiece The contact pressure tends to be the same.

In this embodiment, the upper mold body is a concave mold, and the lower mold body is a convex mold.

Specifically, the upper mold body includes a second insert 215 and a binder core 213, the binder core is installed on the upper mold base, and the second insert 215 is located outside the binder core 213, so The second insert 215 is fixed to the upper mold base 211, and the bottom surface of the pressing core 213 is higher than the bottom surface of the second insert. As a preferred embodiment, an elastic element can be arranged between the pressing core 213 and the upper mold base, and the elastic element can be a nitrogen spring, for example, so that the pressing core can move relative to the upper mold base, and the pressing core can first When the second insert 215 is in contact with the workpiece material, the arrangement of the elastic element can make the pressing core closely adhere to the surface of the workpiece material.

The lower mold body includes a blank holder 236, a first connecting piece 232 and a first insert 233, the first insert is the movable part, and the blank holder 236 is located outside the first insert 233, The top surface of the binder ring is opposite to the bottom surface of the binder core, the binder ring is fixedly connected to the lower mold base 231, the top surface of the first insert is connected to the bottom surface of the binder core In contrast, the first insert is connected to the lower mold base 231 through the first connecting piece 232, and the first connecting piece 232 can provide the first insert 233 with a Floating top material force.

Preferably, the lower die base has a first support member, the first support member is located outside the first connecting member 232, and the blank holder 236 passes through the first support member and the lower die base 231; the first connecting member is a hydraulic cylinder, the lower end of the first insert 233 is connected with the piston rod of the hydraulic cylinder, and the cylinder body of the hydraulic cylinder is connected with the lower mold base 231.

Preferably, the lower mold further includes a lower mold guide 234, the lower mold guide 234 is arranged between the lower mold base 231 and the blank holder 236, and is located outside the first supporting member The upper die also includes an upper die guide 214, the upper die guide 214 is arranged between the upper die base 211 and the blank holder 236, and is located outside the second insert 215.

Preferably, a first guide plate 235 is provided between the outer wall of the first insert 233 and the inner wall of the first support member, and the first guide plate 235 is used to guide the movement of the first insert 233 .

Referring to Fig. 6, there is a groove in the middle of the upper mold base, the binder core 213 is partly located in the groove, the second insert 215 is located at the edge of the groove, and the bottom surface of the binder core 213 is higher than the bottom surface of the second insert 215 . The middle part of the lower mold base has a protruding support member, the bottom surface of the end near the first insert 233 on the blank holder ring 236 is fixed with the support member, and the bottom surface of the end away from the first insert 233 on the blank holder ring 236 is connected to the support member. The upper end of the lower mold guide 234 is connected, and the lower end of the lower mold guide 234 is connected with the lower mold base 231 . The top surface of the end of the blank holder 236 away from the first insert 233 is also connected to the lower end of the upper die guide 214 , and the upper end of the upper die guide 214 is connected to the upper die base 211 . The upper mold guide 214 and the lower mold guide 234 play a supporting and guiding role, and a pressure device can also be arranged on the lower mold guide 234 to measure the pressure applied on the lower mold.

As a preferred embodiment, the lower die guide 234 may include a guide sleeve and a guide post, the lower end of the guide sleeve is fixed on the lower die base 231, the upper end of the guide post is fixed on the blank holder ring 236, The lower end of the guide post penetrates into the guide sleeve. Optionally, the lower mold guide 234 may be a gas spring, preferably a nitrogen gas spring device. As another preferred manner, a pressure gauge may also be installed on the lower mold guide 234 for testing the pressure applied on the lower mold 23 .

As a preferred embodiment, the upper mold guide 214 may include a guide sleeve and a guide column, the upper end of the guide sleeve is fixed on the upper mold base 211, and the lower end of the guide column is fixed on the blank holder 236 , the upper end of the guide post penetrates into the guide sleeve. Optionally, the upper mold guide 214 may be a gas spring, preferably a nitrogen gas spring device.

In this embodiment, the first insert of the lower mold body is designed as a movable part. Compared with the existing fixed structure of the upper and lower molds, the size of the mold cavity can be adjusted through the movable parts, so that the workpiece material and the mold cavity can be more closely fitted. In turn, the externally applied pressure can be evenly transmitted to the surface of the workpiece, so that the contact pressure between the surface of the workpiece and the mold tends to be consistent, so that the deviation caused by various tolerances and cumulative tolerances can be eliminated, and the difference between different sheet materials can be made from the root. The cooling rate tends to be consistent, so that the workpieces produced by multiple cavities can be cooled under the same conditions to achieve the best production efficiency. In addition, since the cooling rate of the workpiece tends to be consistent, it can ensure the formation of complete martensite, ensure that all parts of the workpiece have consistent tensile strength, and improve product yield.

The design of the movable parts of the present invention enables the mold to be adapted to different presses. At the same time, it avoids thermal expansion caused by different cooling rates, which makes the workpiece embedded in the punch, thereby causing damage to the insert and prolonging the service life of the mold.

Embodiment two

This embodiment provides a thermoforming device. As shown in FIG. 7 , the device 2 includes a first substrate 1 , a second substrate 3 and a plurality of molds 2 arranged between the first substrate 1 and the second substrate 3 . Referring to Fig. 6, each mold 2 comprises an upper die 21 and a lower die 23 that cooperate with each other. , the upper mold base 211 is installed on the first substrate 1, the top of the upper mold 21 body is connected to the upper mold base 211, and the lower mold base 231 is installed on the second base plate 3, The bottom of the lower mold body is connected with the lower mold base 231, and a mold cavity for accommodating the workpiece 22 is formed between the bottom of the upper mold 21 body and the top of the lower mold 23 body; The lower mold base 231 is fixedly connected, and the upper mold body has movable parts, and the movable parts are used to change the size of the mold cavity, so that the surface of the mold cavity of each mold in the device is aligned with the surface of the corresponding workpiece. The contact pressure tends to be the same.

In this embodiment, the lower mold body is a convex mold, and the upper mold body is a concave mold.

Specifically, the lower mold body includes a fourth insert 238, the bottom surface of the fourth insert 238 is fixed to the lower mold base 231, and the top surface of the fourth insert has a protrusion. The upper mold body includes a fifth insert 216 and a second connecting piece 217, the fifth insert 216 is the movable part, and the top surface of the fifth insert is connected to the upper mold through the second connecting piece 217. The mold base 211 is connected, the bottom surface of the fifth insert 216 is opposite to the fourth insert 238, the bottom surface of the fifth insert 216 has a concave structure that matches the fourth insert, and the second The connecting piece 217 can provide the fifth insert 216 with a floating ejecting force towards the fourth insert 238 .

Preferably, the second connecting member 217 is a hydraulic cylinder, the upper end of the fifth insert is connected with the piston rod of the hydraulic cylinder, and the cylinder body of the hydraulic cylinder is connected with the upper mold base 211 . The number of the second connecting parts 217 can be multiple.

As a preferred embodiment, the upper mold base 211 has a recessed accommodation groove, the second connecting piece 217 is fixed in the accommodation groove, and the outer periphery of the fifth insert is provided with a convex platform, and the boss is accommodated in the accommodating groove.

As a preferred embodiment, the upper mold body also includes a limiting plate 219, one end of the limiting plate 219 is connected to the edge of the accommodating groove, and the other end of the limiting plate 219 partially covers the accommodating groove The boss of the fifth insert is located above the limit plate 219, and the limit plate 219 can support the boss so as to prevent the fifth insert 216 from breaking away from the accommodating groove. . Depending on the layout of the mold 2, the limiting plate 219 can also be replaced by a side pin or a limiting screw.

Preferably, the upper mold body further includes a second guide plate 218 , and the second guide plate 218 is located between the inner wall of the accommodating groove and the outer wall of the fifth insert 216 . The second guide plate 218 is used to guide the movement of the fifth insert 216 . The second guide 218 may also be a guide post.

It is well known that compared with cold stamping simulation, hot stamping is extremely sensitive to the contact gap and contact pressure of the sheet. Larger contact pressure (20Mpa plane pressure) can bring about 2500W/mm2K surface conduction coefficient, but for 0Mpa without gap, the surface conductance value will drop below 1000W/mm2K. The thermal conductivity of gaps will be further reduced, and this value can be more than four times different, which will have a greater impact on the quenching speed, production cycle, and part quality. However, the present invention designs movable inserts (the stroke of the movable inserts is less than 10 mm to meet the needs), which is realized by providing sufficient holding pressure through the hydraulic jack cylinder, avoiding the influence of the rigid mold body and the press slide block , can eliminate the deviation caused by various tolerances, make the cooling speed of different sheets tend to be consistent from the root, and greatly improve the production efficiency of multi-workpiece production. It can also reduce the defect rate and prolong the service life of the mold insert.

The above description has fully disclosed the specific implementation manners of the present invention. It should be pointed out that any changes made by those skilled in the art to the specific embodiments of the present invention will not depart from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited only to the foregoing specific embodiments.

Claims (10)

1. A thermoforming device, characterized in that it comprises a first base plate (1), a second base plate (3) and a plurality of molds (2) arranged between the first base plate and the second base plate, Each mold (2) comprises a patrix (21) and a counterdie (23) that cooperate with each other, and said patrix (21) comprises a patrix (211) and a patrix body, and said patrix (23) comprises a lower Die base (231) and lower mold body, described upper mold base (211) is installed on the described first substrate (1), the top of described upper mold body is connected with described upper mold base (211), described The lower mold base (231) is installed on the second base plate (3), the bottom of the lower mold body is connected with the lower mold base (231), the bottom of the upper mold body is connected with the bottom of the lower mold body. Between the tops, a mold cavity is formed to accommodate the workpiece; The upper mold body or the lower mold body has movable parts, and the movable parts are used to change the size of the mold cavity, so that the contact between the surface of the mold cavity of each mold in the device and the surface of the corresponding workpiece The pressure tends to be consistent. 2. The device according to claim 1, characterized in that, the upper die body is fixedly connected with the upper die holder (211), and the lower die body has movable parts; The upper mold body is a die, and the upper mold body includes a second insert (215) and a binder core (213), and the binder core (213) is installed on the upper mold base, and the second insert The block (215) is located outside the binder core (213), the second insert is fixed to the upper mold base, and the bottom surface of the binder core is higher than the bottom surface of the second insert; The lower mold body is a punch, and the lower mold body includes a blank holder (236), a first connector (232) and a first insert (233), and the first insert is the movable part, the The binder ring (236) is located outside the first insert (233), the top surface of the binder ring is opposite to the bottom surface of the binder core, and the binder ring is connected to the lower mold base (231 ) is fixedly connected, the top surface of the first insert is opposite to the bottom surface of the binder core, and the first insert is connected to the lower mold base (231) through the first connector (232), The first connecting piece (232) can provide the first insert (233) with a floating ejection force towards the binder core (213). 3. The device according to claim 2, characterized in that, the lower mold base has a first support member, the first support member is located on the outside of the first connecting member (232), and the blank holder (236) Connect with the lower mold base (231) through the first support member; the first connecting member is a hydraulic cylinder, and the lower end of the first insert (233) is connected to the piston rod of the hydraulic cylinder Connected, the cylinder body of the hydraulic cylinder is connected with the lower mold base (231). 4. The device according to claim 3, characterized in that, the lower mold further comprises a lower mold guide (234), and the lower mold guide (234) is arranged between the lower mold base (231) and the lower mold base (231). between the blank holder rings (236), and is located outside the first support member; the upper die also includes an upper die guide (214), and the upper die guide (214) is arranged on the upper die Between the seat (211) and the blank holder (236), and located outside the second insert (215). 5. The device according to claim 3 or 4, characterized in that a first guide plate (235) is further provided between the outer wall of the first insert (233) and the inner wall of the first support member. 6. The device according to claim 1, wherein the lower die body is fixedly connected to the lower die base (231), and the upper die body has movable parts; The lower mold body is a punch, the lower mold body includes a fourth insert (238), the fourth insert (238) is fixed with the lower mold base (231), and the top surface of the fourth insert have a bump; The upper mold body is a die, and the upper mold body includes a fifth insert (216) and a second connector (217), the fifth insert (216) is the movable part, and the fifth insert Connected to the upper mold base (211) through the second connecting piece (217), the fifth insert (216) is opposite to the fourth insert (238), and the fifth insert (216) ) has a concave structure that fits with the fourth insert, and the second connector (217) can provide the fifth insert (216) with a floating top facing the fourth insert (238) Material strength. 7. The device according to claim 6, characterized in that, the second connecting member (217) is a hydraulic cylinder, the upper end of the fifth insert is connected with the piston rod of the hydraulic cylinder, and the hydraulic cylinder The cylinder block is connected with the upper mold base (211). 8. The device according to claim 6, characterized in that, the upper mold base (211) has a recessed accommodation groove, the second connecting piece (217) is fixed in the accommodation groove, A boss is provided on the outer periphery of the fifth insert, and the boss is accommodated in the accommodating groove. 9. The device according to claim 8, characterized in that the upper mold body further comprises a limiting plate (219), one end of the limiting plate (219) is connected to the edge of the accommodating groove, and the limiting plate The other end of (219) partially covers the opening of the accommodating groove, the boss of the fifth insert is located above the limiting plate (219), and the limiting plate (219) can support the The boss thus prevents the fifth insert (216) from detaching from the accommodating groove. 10. The device according to claim 8 or 9, characterized in that, the upper mold body also includes a second guide plate (218), and the second guide plate (218) is located between the inner wall of the accommodating groove and the Between the outer walls of the fifth insert (216).