CN114228065A

CN114228065A - Multi-station injection molding mold

Info

Publication number: CN114228065A
Application number: CN202111425443.1A
Authority: CN
Inventors: 夏天; 孙王敏
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-11-27
Filing date: 2021-11-27
Publication date: 2022-03-25

Abstract

The invention belongs to the field of injection molding, and particularly relates to a multi-station injection molding die which comprises an upper main plate, a lower main plate, hydraulic cylinders, a first die set, a second die set, a third die set and a die assembly, wherein the first die set, the second die set and the third die set are identical in structure, the first die set, the second die set and the third die set are distributed and fixedly connected up and down, the lower surface of the upper main plate is fixedly connected with the upper surface of the first die set, the upper surface of the lower main plate is fixedly connected with the lower surface of the third die set through a backing plate, four corners of the upper surface of the upper main plate are fixedly connected with four hydraulic cylinders, piston rods of the hydraulic cylinders penetrate through the upper main plate and are connected with penetrating positions in a sliding manner, the lower surfaces of the piston rods are fixedly connected with fixing rods, the fixing rods are fixedly connected with four corners of the upper surface of the lower main plate, and are connected in series through adopting three identical injection molding die sets, the structure is simplified, the whole volume is reduced, meanwhile, the raw material waste is reduced, and the cost is saved.

Description

Multi-station injection molding mold

Technical Field

The invention belongs to the field of injection molding, and particularly relates to a multi-station injection molding die.

Background

Injection molding, also known as injection molding, is a method of molding by injection and molding. The injection molding method has the advantages of high production speed, high efficiency, automation of operation, various colors, various shapes from simple to complex, small sizes, accurate product size, easy replacement of products, capability of forming products with complex shapes, and suitability for the molding processing fields of mass production, products with complex shapes and the like. The injection moulding machine is similar to the injection syringe for injection, and is a technological process in which the plasticized plastic in a molten state (i.e. viscous state) is injected into a closed mould cavity by means of the thrust of a screw (or a plunger), and the product is obtained after solidification and shaping. Injection molding is a cyclic process, each cycle consisting essentially of: quantitative feeding, melting and plasticizing, pressure injection, mold filling and cooling, mold opening and mold taking. And taking out the plastic part, closing the mold again, and performing the next cycle.

Most of the existing injection molding molds only have one cavity, and most of a few multi-station injection molding molds adopt a parallel structure, so that the structure is complex, the mold cost is high, the pipeline is long, and more raw materials are wasted.

Disclosure of Invention

The invention aims to provide a multi-station injection molding die, which aims to solve the specific problems that most of the existing injection molding dies are only provided with one cavity, and most of the few multi-station injection molding dies adopt a parallel structure, so that the structure is complex, the manufacturing cost of the die is high, the pipeline is long, and the raw material waste is high.

In order to achieve the purpose, the invention provides the following technical scheme:

a multi-station injection molding mold comprises an upper general plate, a lower general plate, a hydraulic cylinder, a first module, a second module, a third module and a die assembly, the first module, the second module and the third module have the same structure, the first module, the second module and the third module are distributed and fixedly connected up and down, the lower surface of the upper main plate is fixedly connected with the upper surface of the first module, the upper surface of the lower main plate is fixedly connected with the lower surface of the third module through a backing plate, four hydraulic cylinders are fixedly connected with four corners of the upper surface of the upper main plate, piston rods of the hydraulic cylinders penetrate through the upper main plate and are connected with the penetrating positions in a sliding manner, the lower surface of the piston rod is fixedly connected with a fixed rod which is fixedly connected with four corners of the upper surface of the lower main plate, through adopting three the same module of moulding plastics to establish ties mutually, simplified the structure, reduced the raw materials waste simultaneously, saved the cost.

Preferably, the first module comprises an upper die, a lower die, a top plate, a thimble, an air pipe and an electric push rod, the upper die and the lower die are fixedly connected through a spring telescopic guide pillar, when the die is closed, a hydraulic cylinder drives an upper main plate and a lower main plate to clamp the three modules together, when the die is separated, the two main plates increase the distance, the upper die and the lower die of the three modules are automatically separated under the action of the spring telescopic guide pillar, the spring telescopic guide pillar ensures the accuracy of die closing action in the die closing process, a hole is formed in the center of the upper die, a heat exchange pipeline is arranged in the lower die, high-temperature media can be conveyed into the die through the heat exchange pipeline in the injection molding process to ensure that injection molding raw materials cannot be cooled and molded prematurely to block the front end pipeline, when the injection molding is finished and enters a cooling stage, the cooling medium can be conveyed into the die through the heat exchange pipeline to accelerate cooling, and the thimble and the air pipe penetrate through the lower die and are connected with a penetrating position in a sliding and sealing mode, three die cavities are connected in series by the hole of the upper die and the air pipe of the lower die in a die closing state to form a whole closed space, thirty-six ejector pins are divided into four groups, nine ejector pins in each group are uniformly distributed at an equal distance of 3 multiplied by 3, four ejector pins are uniformly distributed on the lower die at a distance of 2 multiplied by 2, the lower end of the air pipe penetrates through the top plate and is fixedly connected with a penetrating position, the air pipe is shorter than the ejector pins, the air pipe cannot be stressed and damaged when the die performs ejection action, strip-shaped counter bores are formed in the upper surfaces of the upper dies of the second die group and the third die group, a closing mechanism is arranged in each counter bore, an electromagnet is fixedly connected to one side of each strip-shaped counter bore, the other side of each strip-shaped counter bore is arc-shaped and is superposed with the inner wall of the hole of the center of the upper die, a sliding block is connected in each strip-shaped hole in a sliding manner, one side of the sliding block, which is close to the center, and the maximum position of the horizontal center radius of the center of the strip-shaped counter bores is the same as the radius of the hole of the center of the upper die, the slider opposite side is a square permanent magnet, and the relative magnetism of the magnetism that shows towards electro-magnet one side with permanent magnet before the stage of moulding plastics, adsorbs the slider and keeps away from center one side, pushes the slider to the centre bore direction through the magnetism reversal that makes the electro-magnet before the pressurize finishes the cooling, lets the shaping product divide into three independent part, avoids the die sinking state to produce and pulls and damage the product, roof and lower mould pass through electric putter fixed connection, and electric putter starts to straighten before the compound die, produces the thrust to roof and lower mould, has guaranteed the roughness of die cavity bottom surface, has avoided the production work piece to produce the flaw.

Preferably, the ejector pin is made of SKD61 die steel materials, and the high-temperature resistance and the wear resistance of the ejector pin are improved by adopting the materials.

Preferably, the first module, the second module and the third module are made of magnesium alloy materials, the weight of the die is reduced on the premise that the rigidity of the die is guaranteed by the aid of the magnesium alloy materials, the effect of the spring guide column is exerted to the maximum, the magnesium alloy materials are good in heat conductivity, and heat transfer can be smooth in the injection molding process and the cooling process.

Preferably, go up total board and total board center down and all seted up the pipeline, it is provided with first valve to go up total board pipeline lower extreme, the pipeline has been seted up at the backing plate center, the pipeline upper end is provided with the second valve, the last mould of first module and lower mould contact surface are provided with seal ring, and under the compound die state, three cavity series connection is a whole, opens the second valve, reduces cavity inner space atmospheric pressure to being close vacuum state through the air pump, and seal ring has guaranteed the gas tightness under the whole clamping state, closes the second valve afterwards, begins the process of moulding plastics from top to bottom through first valve, and because of inside atmospheric pressure is lower, the raw materials of moulding plastics flows in lower floor very easily, lets in the high temperature medium in the heat transfer pipeline in the lower mould simultaneously, has guaranteed the smoothness degree of the process of moulding plastics.

Preferably, the film pressing device comprises a stroke guide pillar, a positioning frame, a moving block and a pneumatic telescopic rod, the lower end of the stroke guide pillar is fixedly connected to the left side wall and the right side wall of the lower main plate in bilateral symmetry distribution, the centers of the left side and the right side of the positioning frame are penetrated through and fixedly connected with the stroke guide pillar, the moving block is in sliding connection with the stroke guide pillar, the pneumatic telescopic rod horizontally penetrates through the moving block and is fixedly connected with a cylinder outside the moving block, after mold separation, the moving block moves to a position between an upper mold and a lower mold of a third module under the driving of a motor, the pneumatic telescopic rod extends out of the cylinder, a wedge-shaped plate at the tail end of the telescopic rod is partially lapped at the edge of the lower mold, then the motor drives the moving block to move downwards, so that the mold is pressed downwards integrally, meanwhile, an electric push rod of the third module is relieved of force, the distance between a top plate and the lower mold is reduced, a thimble extends out, a formed workpiece is ejected from the lower mold, and then the workpiece can be taken out, then the pneumatic telescopic rod retracts, the motor moves to a position between the upper die and the lower die of the second module, the above actions are repeated, the formed workpieces in the second module and the first module are taken out in sequence, and the ejection action is realized.

Compared with the prior art, the invention has the beneficial effects that:

1. the first module, the second module and the third module are fixedly connected in a vertically distributed manner, the cavities are connected in series through the holes of the upper die and the lower die and the air pipes, the series connection quantity can be increased on the same structure according to needs, a plurality of products can be produced through one-time die opening and closing action, the production efficiency is greatly improved, compared with a parallel structure, the structure is simple, the size is small, the cost is saved to a certain extent, meanwhile, the length of a useless pipeline is shortened due to the serial structure, the waste of raw materials is reduced, and the production cost is further saved.

2. Through the setting of the spring guide post in the module, make a plurality of modules open the mould simultaneously through an initiative mechanism, simultaneously through the setting of die assembly, after the mould is divided, the movable block moves to between the last mould of third module and the lower mould under the motor drive, the cylinder stretches out pneumatic telescopic link, make the terminal wedge plate part of telescopic link take at the lower mould edge, the motor drives the movable block downstream afterwards, make the mould wholly push down, the electric putter of third module unloads power simultaneously, roof and lower mould distance reduce, the thimble stretches out, push up the fashioned work piece from the lower mould, can take out the work piece afterwards, then pneumatic telescopic link withdrawal, the motor moves to between the last mould of second module and the lower mould, repeat above action, take out the fashioned work piece in second module and the first module in proper order, ejection action is simplified, ejection action of different strokes of series connection mechanism has been realized.

Drawings

FIG. 1 is a schematic structural view of an open-mold state front view of the present invention;

FIG. 2 is a schematic structural view of a mold closed state front view of the present invention;

FIG. 3 is a sectional view A-A of the front view of the mold-open state of the present invention;

FIG. 4 is a top view of the present invention;

FIG. 5 is an enlarged view of I of FIG. 1 of the present invention;

FIG. 6 is a schematic top view of the operation of the closing mechanism of the present invention;

fig. 7 is a schematic front view of the operation principle of the closing mechanism of the present invention.

In the figure: the device comprises an upper main plate 1, a first valve 11, a lower main plate 2, a hydraulic cylinder 3, a first module 4, an upper die 41, a lower die 42, a top plate 43, a thimble 44, an air pipe 45, an electric push rod 46, a heat exchange pipeline 47, a second module 5, a third module 6, a die assembly 7, a stroke guide post 71, a positioning frame 72, a moving block 73, a pneumatic telescopic rod 74, a backing plate 8, a second valve 81, a closing mechanism 9, an electromagnet 91, a sliding block 92 and a permanent magnet 93.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 to 7, in the embodiment of the present invention, a multi-station injection molding mold comprises an upper main plate 1, a lower main plate 2, hydraulic cylinders 3, a first module 4, a second module 5, a third module 6 and a die assembly 7, wherein the first module 4, the second module 5 and the third module 6 have the same structure, the first module 4, the second module 5 and the third module 6 are distributed vertically and are fixedly connected with each other through a top plate 43 and an upper die 41, the lower surface of the upper main plate 1 is fixedly connected with the upper surface of the first module 4, the upper surface of the lower main plate 2 is fixedly connected with the lower surface of the third module 6 through a backing plate 8, four hydraulic cylinders 3 are fixedly connected with the upper surface of the upper main plate 1, four corners of piston rods of the hydraulic cylinders 3 penetrate through the upper main plate 1 and are slidably connected with a penetrating position, fixing rods are fixedly connected with the lower surfaces of the piston rods, and are fixedly connected with four corners of the upper surface of the lower main plate 2, through adopting three the same module of moulding plastics to establish ties mutually, simplified the structure, increased mould one shot forming's work piece quantity, very big improvement work efficiency.

As an implementation mode of the invention, the first module 4 comprises an upper die 41, a lower die 42, a top plate 43, an ejector pin 44, an air pipe 45 and an electric push rod 46, the upper die 41 and the lower die 42 are fixedly connected through a spring telescopic guide pillar, during die assembly, the hydraulic cylinder 3 drives an upper main plate 1 and a lower main plate 2 to clamp the three modules together, during die separation, the two main plates increase the distance, the upper die and the lower die of the three modules are automatically separated under the action of the spring telescopic guide pillar, the spring telescopic guide pillar ensures the accuracy of die assembly in the die assembly process, a hole is arranged at the center of the upper die 41, a heat exchange pipeline 47 is arranged inside the lower die 42, during the injection molding process, high-temperature media can be conveyed into the die through the heat exchange pipeline 47 to ensure that injection molding raw materials cannot be cooled too early to form and block a front end pipeline, and when the injection molding is finished and enters a cooling stage, cooling media can be conveyed into the die through the heat exchange pipeline 47 to accelerate cooling, the thimble 44 and the air pipe 45 penetrate the lower die 42 and are connected with the penetrating position in a sliding and sealing way, the hole arranged in the middle of the upper die 41 and the air pipe 45 connected with the inner part of the lower die 42 in a sliding way are connected in series to form a whole closed space under the die closing state, thirty-six thimbles 44 are divided into four groups, nine thimbles 44 in each group are uniformly distributed at an equal distance of 3 multiplied by 3, four thimbles 44 are uniformly distributed on the lower die 42 at an equal distance of 2 multiplied by 2, the lower end of the air pipe 45 penetrates the top plate 43 and is fixedly connected with the penetrating position, the upper surfaces of the upper dies of the second die group and the third die group are provided with strip-shaped counter bores, the closing mechanism 9 is arranged in the counter bores, one side of the strip-shaped counter bores away from the center is fixedly connected with an electromagnet 91, the other side of the strip-shaped counter bores is arc-shaped and is superposed with the inner wall of the hole of the center of the upper die, a slide block 92 is in a disc-shaped structure, and the maximum position of the radius of the horizontal center is the same as the radius of the hole of the center of the upper die, the slider 92 opposite side is a square permanent magnet 93, the preceding electro-magnet 91 of stage of moulding plastics shows all the time and permanent magnet 93 towards the opposite magnetism of the magnetism of electro-magnet 91 one side, adsorb the slider in keeping away from center one side, the magnetism that makes electro-magnet 91 is reverse before the pressurize finishes cooling pushes the slider to the centre bore direction, let the shaping product divide into three independent part, it damages the product to avoid the die sinking state to produce to drag, trachea 45 is shorter than thimble 44, trachea 45 can not receive the atress impaired when the mould carries out the liftout action, roof 43 and lower mould 42 pass through electric putter 46 fixed connection, electric putter 46 starts before the compound die to straighten, produce the thrust to roof 43 and lower mould 42, the roughness of die cavity bottom surface has been guaranteed, the production work piece has been avoided producing the flaw.

As an implementation mode of the invention, the ejector pin 44 is made of SKD61 die steel materials, and the high temperature resistance and the wear resistance of the ejector pin 44 are improved by adopting the materials.

As an embodiment of the present invention, the first die set 4, the second die set 5, and the third die set 6 are made of magnesium alloy material, and by using the magnesium alloy material, the weight of the die is reduced on the premise of ensuring the rigidity of the die, so that the function of the spring guide post is exerted to the maximum, and the magnesium alloy material has good thermal conductivity, and can make the heat transfer smoother in the injection molding process and the cooling process.

As an implementation mode of the invention, the centers of the upper main plate 1 and the lower main plate 2 are both provided with pipelines, the lower end of the pipeline of the upper main plate 1 is provided with a first valve 11, the center of the backing plate 8 is provided with a pipeline, the upper end of the pipeline is provided with a second valve 81, the contact surface of the upper die 41 and the lower die 42 of the first module 4 is provided with a sealing gasket, in a die assembly state, the three chambers are connected in series to form a whole, the second valve 81 is opened, the air pressure of the inner space of the chambers is reduced to be close to a vacuum state through an air pump, the sealing gasket ensures the air tightness in the whole clamping state, then the second valve 81 is closed, an injection molding process is started from top to bottom through the first valve 11, and due to the lower inner air pressure, injection molding raw materials can easily flow into the lowest layer, and meanwhile, high-temperature media are introduced into the heat exchange pipeline in the lower die 42, so that the smoothness of the injection molding process is ensured.

As an embodiment of the invention, the film pressing device comprises a stroke guide post 71, a positioning frame 72, a moving block 73 and a pneumatic telescopic rod 74, wherein the lower end of the stroke guide post 71 is fixedly connected to the left and right side walls of the lower header plate 2 in a bilateral symmetry distribution, the centers of the left and right sides of the positioning frame 72 are penetrated and fixedly connected by the stroke guide post 71, the moving block 73 is connected with the stroke guide post 71 in a sliding manner, the pneumatic telescopic rod 74 horizontally penetrates through the moving block 73 and is fixedly connected with an air cylinder outside the moving block 73, after the mold division, the moving block 73 is driven by a motor to move down to a position between the upper mold 41 and the lower mold 42 of the third mold set 6, the air cylinder extends out the pneumatic telescopic rod 74, so that the wedge plate part at the tail end of the telescopic rod is lapped on the edge of the lower mold 42, then the motor drives the moving block 73 to move down, so that the mold is pressed down integrally, and simultaneously, the electric lower mold push rod 46 of the third mold set 6 is released, so that the distance between the top plate 43 and the lower mold 42 is reduced, the ejector pin 44 is extended to eject the formed workpiece from the lower die 42, and then the workpiece can be taken out, then the pneumatic telescopic rod 74 is retracted, the motor moves to a position between the upper die 41 and the lower die 42 of the second die set 5, the above actions are repeated, and the formed workpieces in the second die set 5 and the first die set 4 are taken out in sequence, so that the ejection action is realized.

The working principle is as follows: before injection molding, the electric push rod 46 is started to be straightened to generate thrust to the top plate 43 and the lower die 42, the flatness of the bottom surface of a die cavity is ensured, defects of production workpieces are avoided, during die assembly, the hydraulic cylinder 3 drives the upper main plate 1 and the lower main plate 2 to clamp the three modules together, the spring telescopic guide post ensures the accuracy of die assembly action in the die assembly process, the second valve 81 is opened, the air pressure in the inner space of the cavity is reduced to be close to a vacuum state through an air pump, the air tightness in the integral clamping state is ensured through a sealing washer, then the second valve 81 is closed, an injection molding process is started from top to bottom through the first valve 11, injection molding raw materials easily flow into the lowest layer due to lower internal air pressure, meanwhile, a high-temperature medium is introduced into a heat exchange pipeline in the lower die 42, the smoothness of the injection molding process is ensured, the electromagnet 91 always displays opposite magnetism to the magnetism of the permanent magnet 93 towards one side of the electromagnet 91 before the injection molding stage, adsorbing the slide block on one side far from the center, pushing the slide block to the direction of a center hole by reversing the magnetism of the electromagnet 91 before pressure maintaining and cooling are finished, dividing a formed product into three independent parts, avoiding the damage to the product caused by pulling in a mold opening state, closing the first valve 11 after pressure maintaining and entering a cooling stage, conveying a cooling medium into a mold through a heat exchange pipeline 47 to accelerate cooling, adjusting the polarity of the electromagnet when mold division is finished after cooling, sucking the slide block to the electromagnet, increasing the distance between two main plates through a hydraulic cylinder, automatically separating an upper mold and a lower mold of three modules under the action of a spring telescopic guide post, moving the moving block 73 to a position between the upper mold 41 and the lower mold 42 of the third module 6 under the driving of the motor after mold division is finished, extending the pneumatic telescopic rod 74 through the cylinder, putting the wedge-shaped plate part at the tail end of the telescopic rod on the edge of the lower mold 42, and then driving the moving block 73 to move downwards through the motor, the mold is pressed down integrally, simultaneously the electric push rod 46 of the third module 6 releases force, the distance between the top plate 43 and the lower mold 42 is reduced, the ejector pin 44 extends out to eject the formed workpiece from the lower mold 42, then the workpiece can be taken out, then the pneumatic telescopic rod 74 retracts, the motor moves to the position between the upper mold 41 and the lower mold 42 of the second module 5, the above actions are repeated, the formed workpiece in the second module 5 and the formed workpiece in the first module 4 are taken out in sequence, and the ejection action is realized.

The technical features of the embodiments may be arbitrarily combined, and for brevity, all possible combinations of the technical features in the embodiments are not described, however, as long as the combinations of the technical features do not exist, the embodiments only express several embodiments of the present invention, and the description is more specific and detailed, but the present invention is not limited by the scope of the present invention; it should be noted that, for those skilled in the art, without departing from the concept of the present invention, several variations and modifications can be made, which are within the protection scope of the present invention; therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The utility model provides a multistation injection moulding mould, includes that last board (1), lower board (2), pneumatic cylinder (3), first module (4), second module (5), third module (6), pneumatic cylinder (3) and die assembly (7), its characterized in that always: first module (4), second module (5) and third module (6) structure are the same, first module (4), second module (5) and third module (6) are upper and lower distribution fixed connection, go up total board (1) lower surface and first module (4) upper surface fixed connection, total board (2) upper surface passes through backing plate (8) and third module (6) lower surface fixed connection down, go up four pneumatic cylinders (3) of total board (1) upper surface four corners fixed connection, the piston rod of pneumatic cylinder (3) run through total board (1) and with run through position sliding connection, piston rod lower surface fixed connection has the dead lever, dead lever and total board (2) upper surface four corners fixed connection down.

2. A multi-station injection moulding mould according to claim 1, characterized in that: the first module (4) comprises an upper die (41), a lower die (42), a top plate (43), ejector pins (44), an air pipe (45) and an electric push rod (46), the upper die (41) and the lower die (42) are fixedly connected through a spring telescopic guide pillar, a hole is formed in the center of the upper die (41), a heat exchange pipeline (47) is arranged in the lower die (42), the ejector pins (44) and the air pipe (45) penetrate through the lower die (42) and are in sliding sealing connection with a penetrating position, thirty-six ejector pins (44) are divided into four groups, nine ejector pins (44) in each group are uniformly distributed at an equal distance of 3 multiplied by 3, four groups of ejector pins (44) are uniformly distributed on the lower die (42) at an equal distance of 2 multiplied by 2, the lower end of the air pipe (45) penetrates through the top plate (43) and is fixedly connected with the penetrating position, strip-shaped counter bores are formed in the upper surfaces of the upper dies of the second module and the third module, and a closing mechanism (9) is arranged in each counter bore, the utility model discloses a mould, including bar counter bore, slider (92), roof (43) and lower mould (42), center one side fixedly connected with electro-magnet (91) are kept away from to the bar counter bore, bar counter bore opposite side be the arc and with the downthehole wall coincidence at last mould center, bar downthehole sliding connection has slider (92), one side that slider (92) are close to the center is the dish type structure, slider (92) opposite side is a square permanent magnet (93), trachea (45) are shorter than thimble (44), roof (43) pass through electric putter (46) fixed connection with lower mould (42).

3. A multi-station injection moulding mould according to claim 2, characterized in that: the ejector pins (44) are made of SKD61 die steel materials.

4. A multi-station injection moulding mould according to claim 1, characterized in that: the first module (4), the second module (5) and the third module (6) are made of magnesium alloy materials.

5. A multi-station injection moulding mould according to claim 1, characterized in that: go up total board (1) and total board (2) center down and all seted up the pipeline, it is provided with first valve (11) to go up total board (1) pipeline lower extreme, the pipeline has been seted up at backing plate (8) center, the pipeline upper end is provided with second valve (81), last mould (41) and lower mould (42) contact surface of first module (4) is provided with seal ring.

6. A multi-station injection moulding mould according to claim 1, characterized in that: the die assembly (7) comprises a stroke guide post (71), a positioning frame (72), a moving block (73) and a pneumatic telescopic rod (74), wherein the lower end of the stroke guide post (71) is fixedly connected to the left side wall and the right side wall of the lower header board (2) in bilateral symmetry, the centers of the left side and the right side of the positioning frame (72) are penetrated through and fixedly connected by the stroke guide post (71), the moving block (73) is in sliding connection with the stroke guide post (71), and the pneumatic telescopic rod (74) horizontally penetrates through the moving block (73) and is fixedly connected with an air cylinder on the outer side of the moving block (73).