Servo electric mold opening and closing device in hollow extrusion blow molding machine

Abstract

The utility model discloses a servo electric mold opening and closing device in a hollow extrusion blow molding machine, which comprises a mold moving seat, a front bracket and a rear bracket arranged on the mold moving seat, two mold shafts arranged between the front bracket and the rear bracket in a sliding and penetrating manner, and a vertical seat arranged between the rear ends of the two mold shafts, a swing arm connected with a servo motor is rotatably arranged on the vertical seat, an adjusting rod is hinged in the swing arm, a rear mold plate is rotatably connected to the adjusting rod, the rear mold plate is slidably arranged on two mold shafts in a sleeving mode, a left rack is arranged on the rear mold plate in a backward extending mode, a right rack is arranged on the vertical seat in a forward extending mode, and a synchronous gear is rotatably arranged on the rear bracket. The left side and the right side of the synchronous gear are meshed with the right rack and the left rack respectively, a vertical arm is arranged between the front ends of the two mold shafts, a front mold plate is hinged to the vertical arm, and the two mold shafts are sleeved with the front mold plate in a sliding mode. The device is high in response speed, high in mold closing precision and capable of adjusting the mold opening distance according to the mold thickness.

Description

Technical Field

[0001] This utility model relates to a hollow extrusion blow molding machine, and more particularly to a servo-electric mold opening and closing device in a hollow extrusion blow molding machine. Background Technology

[0002] Currently, most blow molding machines on the market use hydraulic cylinders to drive the mold opening and closing mechanism. Specifically, each mold plate has a hydraulic cylinder, and the opening and closing actions are achieved through synchronous dual-cylinder drive. In the closed state, an additional locking hydraulic cylinder is required to apply a pushing force to the two mold plates to generate a locking force. However, this hydraulic drive method has significant technical drawbacks: First, the hydraulic cylinder generates severe impact loads during the start-up and shutdown phases. The jerking force generated at the moment of start-up can easily cause progressive damage to the guide rail system, reducing mold closing positioning accuracy over long-term operation and ultimately affecting the product molding quality. Second, the hydraulic system needs to circulate oil through pipelines to drive the piston movement. This process has inherent hysteresis characteristics, directly limiting the response speed of the mold opening and closing actions. Third, the design scheme where the hydraulic cylinder directly bears the mold plate drive load increases the load on the actuator. Long-term high-load operation can easily cause wear of hydraulic components, leading to seal failure and oil leakage. This not only poses a risk of environmental pollution but may also cause safety hazards in equipment operation. Utility Model Content

[0003] The purpose of this invention is to provide a servo-electric mold opening and closing device for a hollow extrusion blow molding machine with fast response speed and large clamping force.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is: a servo-electric mold opening and closing device in a hollow extrusion blow molding machine, comprising: a mold transfer base slidably mounted on the machine base; a front support and a rear support mounted on the mold transfer base; two mold shafts slidably passing between the front and rear supports; a stand between the rear ends of the two mold shafts; a bracket mounted on the stand; a swing arm rotatably mounted in the bracket; the swing arm is connected to a servo motor; the servo motor is fixed to the bracket; and an adjusting rod is hinged in the swing arm. A rear template is rotatably connected and slidably fitted onto two mold shafts located between the front and rear brackets. A left rack extends backward from the rear template, and a right rack extends forward from the stand. A synchronizing gear is rotatably mounted on the rear bracket, with its left and right sides meshing with the right and left racks, respectively. A vertical arm is located between the front ends of the two mold shafts, and a front template is hinged to the vertical arm. The front template slidably fits onto two mold shafts located in front of the front bracket, with a hole-shaft gap between the front template and the mold shafts.

[0005] Furthermore, in the aforementioned servo-electric mold opening and closing device of the hollow extrusion blow molding machine, a positioning rod parallel to the mold shaft is provided between the stand and the arm. The front and rear ends of the positioning rod are respectively threadedly connected to two threaded sleeves. The threaded sleeve located at the rear end of the positioning rod is fixed to the stand by bolts, and the rear end of the positioning rod abuts against the stand. The threaded sleeve located at the front end of the positioning rod is fixed to the arm by bolts. An adjustment gap is left between the front end of the positioning rod and the arm. This adjustment gap is also the distance between the front end wall of the positioning rod and the front end wall of the threaded sleeve.

[0006] Furthermore, in the aforementioned servo-electric mold opening and closing device of the hollow extrusion blow molding machine, a sensing plate is provided on the side wall of the rear template, and a mold opening sensor is provided on the mold moving base, with the mold opening sensor and the sensing plate located on the same side.

[0007] Furthermore, in the aforementioned servo-electric mold opening and closing device of the hollow extrusion blow molding machine, a flash hopper is provided on the front bracket, and baffles are provided on the front and rear sides of the flash hopper.

[0008] Furthermore, in the aforementioned servo-electric mold opening and closing device of the hollow extrusion blow molding machine, the connection structure between the synchronous gear and the rear bracket is as follows: a gearbox is provided on the rear bracket, a gear hole is provided in the gearbox, a gear shaft cover is provided in the gear hole, the gear shaft cover is fitted onto the gear hole, the shaft section in the gear shaft cover extends into the gear hole, the synchronous gear is rotated and fitted onto the shaft section of the gear shaft cover, and a left guide hole and a right guide hole communicating with the gear hole are provided on the left and right sides of the gearbox, and the left rack and the right rack are slidably inserted into the left guide hole and the right guide hole respectively.

[0009] Furthermore, in the aforementioned servo-electric mold opening and closing device of the hollow extrusion blow molding machine, the adjusting rod includes: a sleeve and clevises. Internal threads are provided on the inner walls of both ends of the sleeve. Six planes are milled circumferentially on the outer wall of one end of the sleeve. Threaded posts are provided on the clevises. The two clevises are threadedly connected to the two ends of the sleeve through the threaded posts. Locking nuts are threadedly connected to the threaded posts. The locking nuts are screwed and abut against the sleeve. A first pin is fixedly inserted through the swing arm. A hinge seat is provided on the rear template. A second pin is fixedly inserted through the hinge seat. The two clevises on the sleeve are rotatably mounted on the first pin and the second pin, respectively.

[0010] Furthermore, in the aforementioned servo-electric mold opening and closing device of the hollow extrusion blow molding machine, the connection structure between the first pin and the swing arm is the same as the connection structure between the second pin and the hinge seat. Taking the connection structure between the first pin and the swing arm as an example, a shaft hole is provided in the swing arm, and two keyways communicating with the shaft hole are symmetrically provided on one outer side wall of the swing arm. A positioning cover is provided on one end wall of the first pin, and an integral keyway penetrating the other end wall of the first pin is provided. The first pin passes through the shaft hole, and the positioning cover on the first pin abuts against the outer side wall of the swing arm where the keyway is not provided. The integral keyway on the first pin is aligned with the two keyways on the swing arm. A first connecting key is engaged between the relatively aligned keyways and the integral keyway. A pin cover is bolted to the end wall of the first pin where the first connecting key is engaged, and the pin cover abuts against the outer side wall of the swing arm where the keyway is provided.

[0011] Furthermore, in the aforementioned servo-electric mold opening and closing device of the hollow extrusion blow molding machine, the connection structure between the vertical arm and the front template is as follows: a third pin is rotatably installed in the vertical arm, both ends of the third pin extend out of the vertical arm, and clamping blocks are fixedly installed on both ends of the third pin extending out of the vertical arm. A rear keyway is provided on the rear side wall of the clamping block, and two front keyways are provided on the front side wall of the front template. The clamping blocks and the front template are connected by bolts. The two front keyways on the front template are aligned with the rear keyways in the two clamping blocks, and a second connecting key is engaged between the aligned rear keyways and the front keyways.

[0012] The advantages of this invention are as follows: While the servo motor drives the swing arm to rotate, causing the adjusting rod to push and pull the rear template, the left rack on the rear template, in conjunction with the synchronous gear, drives the right rack on the stand to move in the opposite direction, thus causing the stand to move in the opposite direction. The stand, through the mold shaft, drives the upright arm and the front template on the upright arm to move in the opposite direction together. The front and rear templates can perform mold closing or opening actions during their reverse movement. The servo motor, as the power component, improves the response speed between the front and rear templates, thereby increasing the mold opening and closing speed. Furthermore, the servo motor has high motion precision, ensuring the mold closing accuracy between the front and rear templates. Since a servo motor is used for driving, there is no risk of oil leakage like with hydraulic cylinders. The adjusting rod allows for quick adjustment of the distance between the front and rear templates to accommodate mold cores of different thicknesses, improving the applicability. The adjusting rod between the stand and the upright arm allows for fine-tuning of the front template, ensuring that the mold core mounted on the front template remains vertical. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the servo-electric mold opening and closing device in the hollow extrusion blow molding machine described in this utility model.

[0014] Figure 2 yes Figure 1A schematic diagram of the cross-sectional structure.

[0015] Figure 3 yes Figure 1 A schematic diagram of the connection structure between the adjusting rod, the swing arm, and the hinge seat.

[0016] Figure 4 yes Figure 3 A schematic diagram of the cross-sectional structure.

[0017] Figure 5 yes Figure 1 A schematic diagram of the connection structure between the intermediate gearbox and the rear bracket.

[0018] Figure 6 yes Figure 1 A schematic diagram of the connection structure between the central arm and the front template. Detailed Implementation

[0019] The technical solution of this utility model will be further described below with reference to the accompanying drawings and preferred embodiments.

[0020] like Figures 1-6As shown, the servo-electric mold opening and closing device in the hollow extrusion blow molding machine of this utility model includes: a mold transfer base 1 slidably mounted on the machine base; a front bracket 11 and a rear bracket 12 mounted on the mold transfer base 1; a flash hopper 111 mounted on the front bracket 11; baffles mounted upwards on the front and rear sides of the flash hopper 111; two mold shafts 13 slidably passing through between the front bracket 11 and the rear bracket 12; a stand 2 positioned between the rear ends of the two mold shafts 13; a bracket 21 mounted on the stand 2; a swing arm 22 rotatably mounted in the bracket 21; the swing arm 22 being connected to a servo motor 23; the servo motor 23 being fixed to the bracket 21; a first pin 221 mounted on the swing arm 22; an adjusting rod 3 rotatably mounted on the first pin 221; and a rear template 4 slidably mounted on the two mold shafts 13 located between the front bracket 11 and the rear bracket 12. A hinge seat 41 is provided on the rear template 4, and a second pin 411 is provided in the hinge seat 41. The adjusting rod 3 is also rotatably mounted on the second pin 411. The adjusting rod 3 includes a sleeve 31 and an earring 32. Internal threads are provided on the inner walls of both ends of the sleeve 31. Six planes 311 are milled circumferentially on the outer wall of one end of the sleeve 31. Threaded posts are provided on the earring 32. The two earrings 32 are threadedly connected to the two ends of the sleeve 31 through the threaded posts. Locking nuts 33 are threadedly connected to the threaded posts. Locking nuts 33 are screwed and abut against the sleeve 31. The two earrings 32 on the sleeve 31 are rotatably mounted on the first pin 221 and the second pin 411, respectively. The sleeve 31 can be rotated by using a wrench to hold the two symmetrical planes 311 on the sleeve 31, thereby adjusting the distance between the earrings 32 and the sleeve 31 through threaded transmission. The connection structure between the first pin 221 and the rocker arm 22 is the same as the connection structure between the second pin 411 and the hinge seat 41. Taking the connection structure between the first pin 221 and the rocker arm 22 as an example, a shaft hole is provided in the rocker arm 22, and two keyways 222 communicating with the shaft hole are symmetrically provided on one outer side wall of the rocker arm 22. A positioning cover is provided on one end wall of the first pin 221, and an integral keyway 224 penetrating the other end wall of the first pin 221 is provided. The first pin 221 passes through the keyway 224. In the shaft hole, the positioning cover on the first pin 221 abuts against the outer wall of the rocker arm 22 where the keyway 222 is not provided. The integral keyway 224 on the first pin 221 is aligned with the two keyways 222 on the rocker arm 22. A first connecting key 24 is engaged between the relatively aligned keyways 222 and the integral keyway 224. A pin cover 225 is bolted to the end wall of the first pin 221 where the first connecting key 24 is engaged. The pin cover 225 abuts against the outer wall of the rocker arm 22 where the keyway 222 is provided.

[0021] A sensing plate 42 is provided on the side wall of the rear template 4, and a mold opening sensor 14 is provided on the mold transfer base 1. The mold opening sensor 14 and the sensing plate 42 are located on the same side. A left rack 43 is provided extending backward on the rear template 4. The left rack 43 does not contact the stand 2. A right rack 25 is provided extending forward on the stand 2. The right rack 25 does not contact the rear template 4. A gear box 121 is provided on the rear bracket 12. A gear hole is provided in the gear box 121. A gear shaft cover 122 is provided in the gear hole. The gear shaft cover 122 covers the gear hole. The shaft section in the gear shaft cover 122 extends into the gear hole. A synchronous gear 123 is rotatably mounted on the shaft section of the gear shaft cover 122. A left guide hole and a right guide hole communicating with the gear hole are provided on the left and right sides of the gear box 121. The left rack 43 and the right rack 25 are slidably inserted into the left guide hole and the right guide hole respectively and mesh with the synchronous gear 123.

[0022] A vertical arm 5 is provided between the front ends of two mold shafts 13. A third pin 51 is rotatably mounted in the vertical arm 5, with both ends of the third pin 51 extending out of the vertical arm 5. Clamping blocks 52 are fixedly mounted on both ends of the third pin 51 extending out of the vertical arm 5. A front template 6 is connected between the two clamping blocks 52. A rear keyway is provided on the rear side wall of the clamping block 52, and two front keyways are provided on the front side wall of the front template 6. The clamping blocks 52 and the front template 6 are connected by bolts. The two front keyways on the front template 6 are aligned with the rear keyways in the two clamping blocks 52, respectively. A second connecting key 53 is engaged between the aligned rear keyways and the front keyways. The front template 6 slides... On the two mold shafts 13 located on the front side of the front bracket 11, there is a hole-shaft gap between the front template 6 and the mold shaft 13. A positioning rod 7 parallel to the mold shaft 13 is set between the stand 2 and the arm 5. The front and rear ends of the positioning rod 7 are respectively threaded to two threaded sleeves 71. The threaded sleeve 71 located at the rear end of the positioning rod 7 is fixed to the stand 2 by bolts. The rear end of the positioning rod 7 abuts against the stand 2. The threaded sleeve 71 located at the front end of the positioning rod 7 is fixed to the arm 5 by bolts. An adjustment gap h is left between the front end of the positioning rod 7 and the arm 5. The adjustment gap h is the distance between the front end wall of the positioning rod 7 and the front end wall of the threaded sleeve 71.

[0023] When installing the mold, the two mold cores need to be installed on the front template 6 and the rear template 4 respectively. The mold cores installed on the front template 6 and the rear template 4 will not interfere with the front bracket 11 and the flash hopper 111 on the front bracket 11. When installing the mold cores, the distance between the front template 6 and the rear template 4 needs to be adjusted according to the thickness of the mold cores. During adjustment, the sleeve 31 of the adjusting rod 3 is rotated, and the lugs 32 at both ends of the sleeve 31 simultaneously contract or expand through the threaded transmission: when both lugs 32 contract simultaneously, they will pull the rear template 4 backward along the mold shaft 13, and pull the stand 2 forward along the mold shaft 13. The mold shaft 13 will push the upright arm 5 and the front template 6 on the upright arm 5 forward. At this time, the mold opening distance between the front template 6 and the rear template 4 increases, so that thicker molds can be installed. Tighten the locking nut 33 on the ear ring 32 and press it against the sleeve 31 to lock the ear ring 32. When the two ear rings 32 are extended at the same time, they will push the rear template 4 to move forward along the mold shaft 13 and push the upright 2 to move the mold shaft 13 backward. The mold shaft 13 will pull the upright arm 5 and the front template 6 on the upright arm 5 backward. At this time, the mold opening distance between the front template 6 and the rear template 4 decreases, so that thinner molds can be installed.

[0024] During the production of mold cores, due to machining errors, when the two mold cores are installed on the front mold plate 6 and the rear mold plate 4, an angle exists between the two mold cores, preventing them from fully closing during mold assembly. Because the rear mold plate 4 is pulled by the adjusting rod 3 and guided by the mold shaft 13 and the left rack 43, it cannot be adjusted. When the mold core is installed on the rear mold plate 4, it cannot be adjusted by adjusting the rear mold plate 4 itself. However, when the mold core is installed on the front mold plate 6, the mold core on the front mold plate 6 can be adjusted by adjusting the vertical arm 5, allowing the mold core on the front mold plate 6 to fully close with the mold core on the rear mold plate 4. During the adjustment process, the front mold plate 6 is first... The mold core and the mold core of the rear template 4 are closed. When there is a gap between the two mold cores, the bolts between the upright arm 5 and the mold shaft 13 are loosened first. Then the positioning rod 7 is rotated. The positioning rod 7 pushes the threaded sleeve 71 forward or pulls it backward through the threaded transmission, so that the upright arm 5 swings backward or forward with the mold shaft 13 as the fulcrum. When the upright arm 5 swings forward or backward, since there is a hole-shaft gap between the front template 6 and the mold shaft 13, the clamping block 52 can pull the front template 6 and the mold core on the front template 6 to swing backward or forward at the same time until the mold core on the front template 6 and the mold core on the rear template 4 are in contact. After the two mold cores are in contact, the bolts between the upright arm 5 and the mold shaft 13 are tightened. Since the processing error is generally no greater than 0.1°, the swing angle of the upright arm 5 is also small during adjustment, which does not affect the connection stability between the upright arm 5 and the mold shaft 13. Moreover, after the mold core on the front template 6 is adjusted and the mold core on the rear template 4 is closed, it will not affect the fit between the mold head and the mold in the hollow extrusion blow molding machine.

[0025] In use, when the servo motor 23 drives the swing arm 22 to rotate clockwise, it pushes the rear template 4 forward via the adjusting rod 3, causing the rear template 4 to move forward along the mold shaft 13. As the rear template 4 moves forward, it drives the left rack 43 to drive the synchronous gear 123 to rotate counterclockwise. The counterclockwise rotating synchronous gear 123 drives the right rack 25 to move backward. As the right rack 25 moves backward, it pushes the stand 2 backward. The backward-moving stand 2, through the mold shaft 13 and the positioning rod 7, moves the stand arm 5 and the front template 6 backward together. At this time, the two mold cores on the front template 6 and the rear template 4 can close, with the closing position directly above the flash hopper 111. When the servo motor 23 drives the swing arm 22 to rotate counterclockwise... The rear template 4 can be pulled backward by adjusting rod 3, so that the rear template 4 moves backward along mold shaft 13. When the rear template 4 moves backward, it drives the left rack 43 to drive the synchronous gear 123 to rotate clockwise. The clockwise rotating synchronous gear 123 drives the right rack 25 to move forward. At this time, the stand 2 moves forward together with the stand arm 5 and the front template 6 through mold shaft 13 and positioning rod 7. The two mold cores on the front template 6 and the rear template 4 are opened. When the mold is opened, the excess flash in the mold will fall into the flash hopper 111 and will not fall into the mold shaft 13, affecting the smoothness of the mold shaft 13. When the mold is opened, the sensing plate 42 on the rear template 4 is sensed by the mold opening sensor 14, which means that the rear template 4 and the front template 6 have completed the mold opening.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the protection scope of the claims of this utility model.

Claims

1. A servo motor driven mold opening and closing device in a hollow extrusion blow molding machine, comprising: The mold moving seat is slidably arranged on a machine table, characterized in that a front bracket and a rear bracket are arranged on the mold moving seat, two mold shafts are slidably arranged between the front bracket and the rear bracket, a vertical seat is arranged between the rear ends of the two mold shafts, a support is arranged on the vertical seat, a swing arm is rotatably arranged in the support, the swing arm is connected with a servo motor, the servo motor is fixed on the support, an adjusting rod is hingedly arranged in the swing arm, a rear mold plate is rotatably connected on the adjusting rod, the rear mold plate is slidably sleeved on the two mold shafts between the front bracket and the rear bracket, a left rack is arranged on the rear mold plate and extends rearward, a right rack is arranged on the vertical seat and extends forward, a synchronous gear is rotatably arranged on the rear bracket, the left and right sides of the synchronous gear are respectively engaged with the right rack and the left rack, a vertical arm is arranged between the front ends of the two mold shafts, a front mold plate is hingedly arranged on the vertical arm, and the front mold plate is slidably sleeved on the two mold shafts on the front side of the front bracket, and a hole shaft gap exists between the front mold plate and the mold shafts.

2. A servo motor driven opening and closing mold device in a hollow extrusion blow molding machine according to claim 1, characterized in that: A positioning rod parallel to the mold shafts is arranged between the vertical seat and the vertical arm, the front and rear ends of the positioning rod are respectively threadedly connected with two threaded sleeves, the threaded sleeve at the rear end of the positioning rod is fixed on the vertical seat by bolts, the rear end of the positioning rod abuts against the vertical seat, the threaded sleeve at the front end of the positioning rod is fixed on the vertical arm by bolts, and an adjusting gap is left between the front end of the positioning rod and the vertical arm, which is also the distance between the front end wall of the positioning rod and the front end wall of the threaded sleeve.

3. The servo motor driven opening and closing mold device in a hollow extrusion blow molding machine according to claim 1, characterized in that: A sensing plate is arranged on the side wall of the rear mold plate, and a mold opening sensor is arranged on the mold moving seat and located on the same side as the sensing plate.

4. The servo motor driven opening and closing mold device in a hollow extrusion blow molding machine according to claim 1, characterized by: A flash falling hopper is arranged on the front bracket, and baffles are upwardly arranged on the front and rear sides of the flash falling hopper.

5. The servo motor driven opening and closing mold device in a hollow extrusion blow molding machine according to claim 1, characterized by: The connection structure between the synchronous gear and the rear bracket is that a gear box is arranged on the rear bracket, a gear hole is arranged in the gear box, a gear shaft cover is arranged in the gear hole, the gear shaft cover covers the gear hole, a shaft section in the gear shaft cover extends into the gear hole, the synchronous gear is rotatably sleeved on the shaft section of the gear shaft cover, left and right guide holes are arranged on the left and right sides of the gear box and communicate with the gear hole, and the left rack and the right rack are respectively slidably inserted into the left guide hole and the right guide hole.

6. The servo motor driven opening and closing mold device in a hollow extrusion blow molding machine according to claim 1, characterized by: The adjusting rod comprises a sleeve, an ear ring, inner threads are arranged on the inner walls of the two ends of the sleeve, six planes are circumferentially milled on the outer side wall of one end of the sleeve, a threaded column is arranged on the ear ring, the two ear rings are respectively threadedly connected to the two ends of the sleeve through the threaded column, a locking nut is threadedly connected to the threaded column and abuts against the sleeve, a first pin shaft is fixedly arranged in the swing arm, a second pin shaft is fixedly arranged in the hinging seat arranged on the rear mold plate, and the two ear rings of the sleeve are respectively rotatably arranged on the first pin shaft and the second pin shaft.

7. A servo motor driven opening and closing mold device in a hollow extrusion blow molding machine according to claim 6, wherein: The connecting structure between the first pin shaft and the swing arm and the connecting structure between the second pin shaft and the hinge seat are the same. Taking the connecting structure between the first pin shaft and the swing arm as an example, a shaft hole is arranged in the swing arm, two split key grooves which are symmetrical and communicate with the shaft hole are arranged on an outer side wall of the swing arm, a positioning cover is arranged on one end wall of the first pin shaft, an integral key groove which penetrates the end wall is formed on the other end wall of the first pin shaft, the first pin shaft is arranged in the shaft hole, the positioning cover on the first pin shaft abuts against the outer side wall of the swing arm which is not provided with the split key groove, the integral key groove on the first pin shaft is in line with the two split key grooves on the swing arm, a first connecting key is clamped between the split key grooves and the integral key groove which are in line, a pin shaft cover is connected to the end wall of the first pin shaft on which the first connecting key is clamped through bolts, and the pin shaft cover abuts against the outer side wall of the swing arm which is provided with the split key groove.

8. The servo motor driven opening and closing mold device in the hollow extrusion blow molding machine according to claim 1, characterized in that: The connecting structure between the vertical arm and the front template is that a third pin shaft is rotatably arranged in the vertical arm, both ends of the third pin shaft extend out of the vertical arm, clamping blocks are fixedly arranged on both ends of the third pin shaft which extend out of the vertical arm, rear key grooves are arranged on the rear side walls of the clamping blocks, two front key grooves are arranged on the front side wall of the front template, the clamping blocks and the front template are connected through bolts, the two front key grooves on the front template are respectively in line with the rear key grooves in the two clamping blocks, and a second connecting key is clamped between the aligned rear key grooves and front key grooves.

Images