Pipe cutting apparatus with follow-up receiving mechanism

Abstract

The utility model discloses a kind of pipe cutting device with follow-up material receiving mechanism, it is related to laser pipe cutting machine technical field, front chuck is set on bed body, rear chuck and head structure are also set on bed body, front chuck is used to hold pipe material and rotates, rear chuck is used to hold the tail end of pipe material and carries out feeding, head structure is used for the cutting of pipe material, bed body is composed of first bed body and second bed body, second bed body is fixedly installed on the left side of first bed body, and second bed body is higher than first bed body, the horizontal top surface of first bed body is provided with first guide rail, the horizontal top surface of second bed body is provided with second guide rail and rack, rack is located between first guide rail and second guide rail.The front chuck of the device can move on bed body, can be moved to the other side of laser head, the tail end of tail material pipe is processed, the utilization of tail material is improved, front chuck is connected with follow-up material receiving mechanism, can discharge at any time, not limited by workpiece length.

Description

Technical Field

[0001] This utility model relates to the field of laser tube cutting machine technology, and in particular to a tube cutting device with a follow-up receiving mechanism. Background Technology

[0002] Existing laser tube cutting machines typically have two chucks: a rear chuck for feeding and a front chuck for clamping and rotating the tube for cutting. After the tube is cut, it is unloaded by the unloading mechanism under the clamping of the front chuck. The front chuck in the existing technology is usually fixedly mounted on the machine bed and can only process tubes on the side close to the laser head. It cannot process tubes on the side away from the laser head, nor can it process the tail end of the tube.

[0003] In the existing technology, due to the certain distance between the front chuck and the unloading mechanism, longer pipes can fall directly onto the unloading mechanism after cutting, while shorter tail pipes cannot fall directly onto the unloading mechanism after cutting. A third chuck needs to be added to the machine bed to clamp the cut tail material and move it onto the unloading mechanism. Adding a third chuck requires configuring a corresponding moving mechanism and control mechanism, making the pipe cutting machine more complex and increasing the operating cost. Utility Model Content

[0004] The purpose of this application is to provide a pipe cutting device with a follow-up receiving mechanism. The front chuck is connected to the follow-up receiving mechanism, which can unload materials at any time without being limited by the length of the workpiece. This eliminates the need for a third chuck to unload the tail material, effectively reducing waste of tail material and improving the utilization rate of pipes without significantly increasing costs.

[0005] To achieve the above objectives, this application provides the following technical solution: a pipe cutting device with a follow-up receiving mechanism, wherein a front chuck is disposed on the bed, the front chuck is used to clamp the pipe for rotation, the bed is composed of a first bed body and a second bed body, the second bed body is fixedly installed on the left side of the first bed body and is higher than the first bed body, a first guide rail is disposed on the horizontal top surface of the first bed body, a second guide rail and a rack are disposed on the horizontal top surface of the second bed body, the rack is located between the first guide rail and the second guide rail, a follow-up receiving mechanism is disposed on the front side of the front chuck, the follow-up receiving mechanism is used for receiving the pipe after cutting, a first connecting plate and a second connecting plate are disposed between the front chuck and the follow-up receiving mechanism, a plurality of fourth sliders adapted to the first guide rail are disposed on the first connecting plate, and a plurality of fifth sliders adapted to the second guide rail are disposed on the second connecting plate; The front chuck includes a sliding seat. Several first sliders adapted to the second guide rail are mounted on the bottom left side of the sliding seat. A support frame is provided on the bottom right side of the sliding seat. Several second sliders adapted to the first guide rail are mounted on the bottom of the support frame. A first servo motor is mounted on the upper part of the sliding seat. The first servo motor is connected to a first reducer via a coupling. The output end of the first reducer extends to the lower part of the sliding seat and is connected to a gear. The gear meshes with a rack. A side bracket is provided on the upper part of the sliding seat. A clamping chuck is mounted on the side bracket. The clamping chuck is used to clamp the pipe for rotation.

[0006] Furthermore, a material receiving protective cover is provided between the front chuck and the follow-up material receiving mechanism.

[0007] Furthermore, the follow-up receiving mechanism includes a frame, a lifting frame is provided on the right side of the frame, a first connecting plate is fixedly installed between the frame and the support frame, a connecting frame is provided on the frame, a second connecting plate is fixedly installed between the connecting frame and the sliding seat, a plurality of third guide rails are provided on the right side wall of the frame, a plurality of third sliders adapted to the third guide rails are installed on the left side of the lifting frame, a lead screw is rotatably installed on the right side of the frame, a first synchronous pulley is connected to the lower end of the lead screw, a motor base is installed on the frame, a second servo motor is installed on the motor base, a second reducer is connected to the second servo motor through a coupling, a second synchronous pulley is connected to the output end of the second reducer, the first synchronous pulley and the second synchronous pulley are connected by a synchronous belt, a lead screw nut is installed on the lead screw, and the lead screw nut is fixedly connected to the lifting frame.

[0008] Furthermore, the upper part of the lifting frame is provided with a receiving plate, and the top of the lifting frame is hinged to the rear part of the receiving plate. Two cylinder seats are provided on the right side of the lifting frame. The cylinder seats are inclined at an angle to the horizontal direction. Two cylinders are provided on the right side of the lifting frame. The cylinder body is hinged to the cylinder seat, and the piston rod of the cylinder is hinged to the front part of the receiving plate.

[0009] Furthermore, the receiving plate is provided with several nylon plates with triangular cross-sections, and the receiving plate is also provided with several rollers.

[0010] Furthermore, the sliding seat is provided with a backlash adjustment mechanism.

[0011] Furthermore, the backlash adjustment mechanism includes an adjustment seat and a tensioning seat, both of which are located on the upper part of the sliding seat. A gear hole is provided at the center of the adjustment seat, and several mounting holes are provided on the adjustment seat. The mounting holes are evenly distributed circumferentially around the gear hole. The first reducer is fixedly mounted on the adjustment seat by a second screw and mounting holes. Adjustment holes are provided at the four corners of the adjustment seat. The adjustment holes are elongated and their length direction is perpendicular to the length direction of the rack. Four fixing holes are provided on the sliding seat, and the fixing holes correspond to the adjustment holes. The adjustment seat is fixedly mounted on the sliding seat by a third screw, fixing holes, and adjustment holes.

[0012] Furthermore, two tensioning holes are provided on the side wall of the adjusting seat. Both the tensioning holes and the fixing holes are threaded holes. Two positioning holes are provided on the tensioning seat. The two positioning holes correspond to the two tensioning holes. A first screw is installed in the positioning hole and is threadedly connected to the tensioning hole.

[0013] In summary, the technical effects and advantages of this utility model are as follows: In this invention, the front chuck of the device can move on the bed and to the other side of the laser head to process the tail end of the tube material, thus improving the utilization rate of the tail material. The front chuck is connected to a follow-up receiving mechanism, which can unload materials at any time without being limited by the length of the workpiece. This eliminates the need for a third chuck in the tube cutting machine to unload the tail material, effectively reducing waste. Without significantly increasing costs, it effectively improves the utilization rate of the tube material and saves costs for the enterprise. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the embodiments or the prior art will be briefly introduced below.

[0015] Figure 1 This is a three-dimensional structural diagram of the high-low track laser tube cutting machine in the embodiments of this application; Figure 2 This is a three-dimensional structural diagram of the bed in an embodiment of this application; Figure 3 This is a diagram showing the connection relationship between the bed, the first guide rail, the second guide rail, and the rack in an embodiment of this application. Figure 4 This is a three-dimensional structural diagram of the front chuck in an embodiment of this application; Figure 5 This is a partial structural diagram of the front chuck in an embodiment of this application; Figure 6 This is a diagram showing the positional relationship between the first servo motor and the backlash adjustment mechanism in an embodiment of this application. Figure 7 This is a diagram showing the positional relationship between the sliding seat, the first servo motor, and the gear in an embodiment of this application. Figure 8 This is a three-dimensional structural diagram of the backlash adjustment mechanism in the embodiments of this application; Figure 9 This is a diagram showing the connection relationship between the front chuck, the follow-up receiving mechanism, and the receiving protective cover in the embodiments of this application; Figure 10 Examples of embodiments in this application Figure 9 Another perspective view; Figure 11 This is a three-dimensional structural diagram of the follow-up material receiving mechanism in the embodiments of this application; Figure 12 This is a partial structural schematic diagram of the follow-up material receiving mechanism in the embodiments of this application; Figure 13 Examples of embodiments in this application Figure 12 Another perspective view; Figure 14 Examples of embodiments in this application Figure 13 Partial structural diagram; Figure 15 Examples of embodiments in this application Figure 14 Partial structural diagram; Figure 16 This is a diagram showing the positional relationship between the front chuck, the follow-up receiving mechanism, and the head structure in the embodiments of this application.

[0016] In the diagram: 1. Front chuck; 101. Sliding seat; 102. First slider; 103. Support frame; 104. Second slider; 105. First servo motor; 106. Gear; 107. Side bracket; 108. Clamping chuck; 109. Fixing hole; 2. Rear chuck; 3. Follow-up receiving mechanism; 301. Frame; 302. Lifting frame; 303. Third guide rail; 304. Third slider; 305. Lead screw; 306. First synchronous pulley; 307. Motor base; 308. Second servo motor; 309. Second synchronous pulley 310. Wire nut seat; 311. Receiving plate; 312. Cylinder seat; 313. Cylinder; 314. Connecting frame; 315. Nylon plate; 316. Roller; 4. First bed; 5. Second bed; 6. First guide rail; 7. Second guide rail; 8. Rack; 9. First connecting plate; 10. Fourth slider; 11. Second connecting plate; 12. Fifth slider; 13. Receiving protective cover; 14. Machine head structure; 15. Adjusting seat; 16. Tensioning seat; 17. Gear hole; 18. Mounting hole; 19. Adjusting hole; 20. First screw. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0018] Example: Reference Figures 1-16 The diagram shows a pipe cutting device with a follow-up feeding mechanism. A front chuck 1 is mounted on the machine bed, which also houses a rear chuck 2 and a head structure 14. The front chuck 1 is used to clamp and rotate the pipe, while the rear chuck 2 is used to clamp the tail end of the pipe for feeding. A laser head in the head structure 14 is used for cutting the pipe. The machine bed consists of a first bed 4 and a second bed 5. The second bed 5 is fixedly installed on the left side of the first bed 4 and is higher than the first bed 4. A first guide rail 6 is provided on the horizontal top surface of the first bed 4, and a second guide rail 6 is provided on the horizontal top surface of the second bed 5. The chuck 1 is equipped with a second guide rail 7 and a rack 8, with the rack 8 located between the first guide rail 6 and the second guide rail 7. A follow-up receiving mechanism 3 is provided on the front side of the chuck 1. The follow-up receiving mechanism 3 is used to receive the material after the pipe is cut. A first connecting plate 9 and a second connecting plate 11 are provided between the chuck 1 and the follow-up receiving mechanism 3. The first connecting plate 9 is provided with a plurality of fourth sliders 10 that are adapted to the first guide rail 6. The second connecting plate 11 is provided with a plurality of fifth sliders 12 that are adapted to the second guide rail 7. A receiving protective cover 13 is provided between the chuck 1 and the follow-up receiving mechanism 3. The follower receiving mechanism 3 is connected to the front chuck 1 via the first connecting plate 9 and the second connecting plate 11. The follower receiving mechanism 3 can move on the first guide rail 6 and the second guide rail 7 via the fourth slider 10 and the fifth slider 12. When the front chuck 1 moves under the drive of the first servo motor 105, it can drive the follower receiving mechanism 3 to move synchronously, so that the follower receiving mechanism 3 can always maintain a fixed distance from the front chuck 1. For shorter tail material tubes, after the front chuck 1 has finished cutting, it can fall directly onto the receiving plate 311 of the follower receiving mechanism 3 and complete the unloading. Therefore, it is not necessary to add a third chuck on the bed to clamp the cut tail material and move the cut tail material tube to the unloading mechanism. Existing side-mounted pipe cutting machines have guide rails set on a vertical plane. The hanging structure has limitations in stability and is not strong enough to support the cutting of large-diameter and long pipes. The side-mounted front chuck also generates significant vibration during rotation, which affects the cutting accuracy. This device sets both the first guide rail 6 and the second guide rail 7 on a horizontal plane, and the two guide rails are at different heights. The guide rail on the side closer to the sliding device is lower. Therefore, the stability of the front chuck 1 and the follow-up receiving mechanism 3 on the guide rails, as well as the support capacity for cutting large-diameter and long pipes, are improved. The front chuck 1 generates less vibration during rotation, which can improve the cutting accuracy.

[0019] The front chuck 1 includes a sliding seat 101. Multiple first sliders 102 adapted to the second guide rail 7 are installed on the bottom left side of the sliding seat 101. A support frame 103 is provided on the bottom right side of the sliding seat 101. Multiple second sliders 104 adapted to the first guide rail 6 are installed on the bottom of the support frame 103. A first servo motor 105 is installed on the upper part of the sliding seat 101. The first servo motor 105 is connected to a first reducer through a coupling. The output end of the first reducer extends to the lower part of the sliding seat 101 and is connected to a gear 106. The gear 106 meshes with a rack 8. A side bracket 107 is provided on the upper part of the sliding seat 101. A clamping chuck 108 is installed on the side bracket 107. The clamping chuck 108 is used to clamp the pipe and rotate it, and cooperate with the head structure 14 to cut the pipe. The first servo motor 105 drives the gear 106 to move along the rack 8, thereby driving the front chuck 1 to move horizontally on the bed. This allows the front chuck 1 to not only process the tubes near the laser head, but also to clamp the tubes and move them to the other side of the laser head to process the tubes away from the laser head, thus enabling the processing of the tail end of the tube.

[0020] The following material receiving mechanism 3 includes a frame 301, a lifting frame 302 on the right side of the frame 301, a first connecting plate 9 fixedly installed between the frame 301 and the support frame 103, a connecting frame 314 on the frame 301, a second connecting plate 11 fixedly installed between the connecting frame 314 and the sliding seat 101, multiple third guide rails 303 on the right side wall of the frame 301, multiple third sliders 304 adapted to the third guide rails 303 installed on the left side of the lifting frame 302, a lead screw 305 rotatably installed on the right side of the frame 301, and a first synchronous pulley 306 connected to the lower end of the lead screw 305. A motor mount 307 is installed on the 301, and a second servo motor 308 is installed on the motor mount 307. The second servo motor 308 is connected to a second reducer via a coupling. The output end of the second reducer is connected to a second synchronous pulley 309. The first synchronous pulley 306 and the second synchronous pulley 309 are connected via a synchronous belt. The second servo motor 308 drives the lead screw 305 to rotate, which can drive the lifting frame 302 to rise and fall. A lead screw nut 310 is installed on the lead screw 305 and is fixedly connected to the lifting frame 302. A receiving plate 311 is provided on the upper part of the lifting frame 302, and the top of the lifting frame 302... The receiving plate 311 is hinged to its rear, allowing it to flip. Two cylinder seats 312 are located on the right side of the lifting frame 302, at an angle to the horizontal. Two cylinders 313 are also located on the right side of the lifting frame 302. The cylinder body of each cylinder 313 is hinged to the cylinder seat 312, and the piston rod of each cylinder 313 is hinged to the front of the receiving plate 311. When the piston rod of the cylinder 313 extends outward, the receiving plate 311 is in a horizontal position, allowing it to receive material. When the piston rod of the receiving plate 311 retracts, it causes the receiving plate 311 to flip downward, allowing the received pipe to slide along the receiving plate 311. 11. After the pipe is cut, it slides down and is unloaded. The lifting frame 302 is driven to rise and fall by the second servo motor 308, so that the receiving plate 311 can adjust the receiving height according to the pipe with different diameters, and play the role of following the receiving. The receiving plate 311 is provided with multiple nylon plates 315 with triangular cross sections, which are used to limit the pipe and facilitate the unloading of the pipe by the receiving plate 311. The receiving plate 311 is provided with multiple rollers 316, and the axis of the rollers 316 is perpendicular to the axis of the pipe. The rollers 316 facilitate the movement of the pipe on the receiving plate 311 and reduce the friction between the pipe and the receiving plate 311.

[0021] Among them, the sliding seat 101 is provided with a backlash adjustment mechanism; Because gear 106 and rack 8 need to mesh to drive the rear chuck 2 and front chuck 1 to move, in the prior art, the meshing degree of gear and rack can usually only be guaranteed by the precision of machining. The gear and rack need to be machined within the tolerance zone, which may result in errors. Moreover, the meshing between gear and rack cannot be flexibly adjusted. The backlash adjustment mechanism includes an adjustment seat 15 and a tensioning seat 16. Both the adjustment seat 15 and the tensioning seat 16 are located on the upper part of the sliding seat 101. The tensioning seat 16 is located between the adjustment seat 15 and the bed. Two tensioning holes are opened on the side wall of the adjustment seat 15. Both the tensioning holes and the fixing holes 109 are threaded holes. The axis of the tensioning holes is perpendicular to the length direction of the rack 8. Two positioning holes are opened on the tensioning seat 16. The two positioning holes correspond to the two tensioning holes. A first screw 20 is installed in the positioning hole and is threadedly connected to the tensioning hole. When there is a certain gap between gear 106 and rack 8 that needs to be adjusted, the first screw 20 in the positioning hole is tightened. During the tightening process, the nut of the first screw 20 will press against the tensioning seat 16. During the rotation of the screw 20, the adjusting seat 15 will be pulled. The adjusting seat 15 will gradually move towards the tensioning seat 16 and drive gear 106 towards rack 8, so that gear 106 and rack 8 mesh to eliminate the gap between gear 106 and rack 8. After gear 106 and rack 8 are meshed, the tightening of the first screw 20 can be stopped, thereby completing the flexible adjustment of gear 106 and rack 8. The backlash adjustment mechanism has a simple structure and can be completed by improving the existing equipment. A gear hole 17 is provided at the center of the adjusting seat 15, and multiple mounting holes 18 are provided on the adjusting seat 15. The mounting holes 18 are evenly distributed circumferentially around the gear hole 17. The first reducer is fixedly installed on the adjusting seat 15 by the second screw and the mounting holes 18. Adjusting holes 19 are provided at the four corners of the adjusting seat 15. The adjusting holes 19 are elongated and their length direction is perpendicular to the length direction of the rack 8. Four fixing holes 109 are provided on the sliding seat 101. The fixing holes 109 correspond to the adjusting holes 19. The adjusting seat 15 is fixedly installed on the sliding seat 101 by the third screw, the fixing holes 109, and the adjusting holes 19. Since the adjusting holes 19 are elongated, the adjusting seat 15 can move relative to the sliding seat 101 within the length range of the adjusting holes 19 after it is installed.

[0022] The cylinder is equipped with a power source, and the power source is configured as a standard feature in the field, which technicians can accomplish based on existing technology.

[0023] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A pipe cutting device with a follow-up receiving mechanism, characterized in that: A front chuck (1) is mounted on the bed and is used to clamp the tube for rotation. The bed consists of a first bed body (4) and a second bed body (5). The second bed body (5) is fixedly mounted on the left side of the first bed body (4) and is higher than the first bed body (4). A first guide rail (6) is provided on the horizontal top surface of the first bed body (4), and a second guide rail (7) and a rack (8) are provided on the horizontal top surface of the second bed body (5). The rack (8) is located between the first guide rail (6) and the second guide rail (7). Between the two guide rails (7), a follower receiving mechanism (3) is provided on the front side of the front chuck (1). The follower receiving mechanism (3) is used to receive the material after the pipe is cut. A first connecting plate (9) and a second connecting plate (11) are provided between the front chuck (1) and the follower receiving mechanism (3). A number of fourth sliders (10) adapted to the first guide rail (6) are provided on the first connecting plate (9). A number of fifth sliders (12) adapted to the second guide rail (7) are provided on the second connecting plate (11). The front chuck (1) includes a sliding seat (101). Several first sliders (102) adapted to the second guide rail (7) are installed on the bottom left side of the sliding seat (101). A support frame (103) is provided on the bottom right side of the sliding seat (101). Several second sliders (104) adapted to the first guide rail (6) are installed on the bottom of the support frame (103). A first servo motor (105) is installed on the upper part of the sliding seat (101). The first servo motor (105) is connected to a first reducer through a coupling. The output end of the first reducer extends to the lower part of the sliding seat (101) and is connected to a gear (106). The gear (106) meshes with a rack (8). A side bracket (107) is provided on the upper part of the sliding seat (101). A clamping chuck (108) is installed on the side bracket (107). The clamping chuck (108) is used to clamp the pipe for rotation.

2. The pipe cutting device with a follow-up receiving mechanism according to claim 1, characterized in that: A material receiving protective cover (13) is provided between the front chuck (1) and the follow-up material receiving mechanism (3).

3. The pipe cutting device with a follow-up receiving mechanism according to claim 1, characterized in that: The follow-up receiving mechanism (3) includes a frame (301), a lifting frame (302) is provided on the right side of the frame (301), a first connecting plate (9) is fixedly installed between the frame (301) and the support frame (103), a connecting frame (314) is provided on the frame (301), a second connecting plate (11) is fixedly installed between the connecting frame (314) and the sliding seat (101), a plurality of third guide rails (303) are provided on the right side wall of the frame (301), a plurality of third sliders (304) adapted to the third guide rails (303) are installed on the left side of the lifting frame (302), and the right side of the frame (301) A lead screw (305) is rotatably mounted, and a first synchronous pulley (306) is connected to the lower end of the lead screw (305). A motor mount (307) is mounted on the frame (301), and a second servo motor (308) is mounted on the motor mount (307). The second servo motor (308) is connected to a second reducer through a coupling. The output end of the second reducer is connected to a second synchronous pulley (309). The first synchronous pulley (306) and the second synchronous pulley (309) are connected by a synchronous belt. A lead screw nut (310) is mounted on the lead screw (305), and the lead screw nut (310) is fixedly connected to the lifting frame (302).

4. The pipe cutting device with a follow-up receiving mechanism according to claim 3, characterized in that: The upper part of the lifting frame (302) is provided with a receiving plate (311), and the top of the lifting frame (302) is hinged to the rear of the receiving plate (311). Two cylinder seats (312) are provided on the right side of the lifting frame (302). The cylinder seats (312) are inclined at an angle to the horizontal direction. Two cylinders (313) are provided on the right side of the lifting frame (302). The cylinder body of the cylinder (313) is hinged to the cylinder seat (312), and the piston rod of the cylinder (313) is hinged to the front of the receiving plate (311).

5. The pipe cutting device with a follow-up receiving mechanism according to claim 4, characterized in that: The receiving plate (311) is provided with a number of nylon plates (315) with triangular cross sections, and the receiving plate (311) is provided with a number of rollers (316).

6. The pipe cutting device with a follow-up receiving mechanism according to claim 1, characterized in that: The sliding seat (101) is provided with a backlash adjustment mechanism.

7. The pipe cutting device with a follow-up receiving mechanism according to claim 6, characterized in that: The backlash adjustment mechanism includes an adjustment seat (15) and a tensioning seat (16). Both the adjustment seat (15) and the tensioning seat (16) are located on the upper part of the sliding seat (101). A gear hole (17) is provided at the center of the adjustment seat (15), and several mounting holes (18) are provided on the adjustment seat (15). The mounting holes (18) are evenly distributed circumferentially around the gear hole (17). The first reducer is fixedly installed on the adjustment seat (15) by a second screw and the mounting holes (18). On the sliding seat (101), adjustment holes (19) are provided at the four corners of the adjustment seat (15). The adjustment holes (19) are elongated and the length direction of the adjustment holes (19) is perpendicular to the length direction of the rack (8). Four fixing holes (109) are provided on the sliding seat (101). The fixing holes (109) correspond to the adjustment holes (19). The adjustment seat (15) is fixedly installed on the sliding seat (101) by the third screw, the fixing holes (109) and the adjustment holes (19).

8. The pipe cutting device with a follow-up receiving mechanism according to claim 7, characterized in that: The adjusting seat (15) has two tensioning holes on its side wall. Both the tensioning holes and the fixing holes (109) are threaded holes. The tensioning seat (16) has two positioning holes. The two positioning holes correspond to the two tensioning holes. A first screw (20) is installed in the positioning hole. The first screw (20) is threadedly connected to the tensioning hole.

Images