High-precision mechanical measurement and automatic calibration integrated equipment

Abstract

The invention provides high-precision mechanical measurement and automatic calibration integrated equipment, and relates to the technical field of mechanical measurement. The high-precision mechanical measurement and automatic calibration integrated equipment comprises a base and a control table, the control table is arranged on one side of the base, a second storage box is fixedly connected to the center of the upper end face of the base, and a switching structure is arranged on the upper end face of the rear end of the base. Stand columns are fixedly connected to the upper end faces of the portions, on the two sides of the second storage box, of the base correspondingly, a top plate is fixedly connected to the upper ends of the stand columns, sliding grooves are formed in the positions, close to the centers of the inner side walls, of the two stand columns correspondingly, sliding blocks are arranged in the two sliding grooves, and a lifting structure is arranged at the position, close to the upper portion, of the center in the base and comprises a mounting plate; a servo motor is fixedly connected to the front portion of one side of the upper end face of the mounting plate, and a transmission worm is fixedly connected to the output end of the servo motor. And the height of the sliding block is adjusted through the lifting structure, so that objects with different sizes can be metered conveniently.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical metrology, and specifically to an integrated device for high-precision mechanical metrology and automatic calibration. Background Technique

[0002] Mechanical metrology equipment is a precision instrument used to measure and calibrate mechanical parameters, and is widely used in fields such as industrial manufacturing, scientific research experiments, and quality control. Tensile and pressure metrology equipment is an important part of the mechanical metrology field and is widely used in multiple fields such as industrial manufacturing, scientific research experiments, quality control and certification. With the rapid development of modern industry and technology, higher requirements are put forward for the accuracy, efficiency, and automation level of mechanical metrology and calibration.

[0003] There are still some problems in the use of existing high-precision mechanical metrology equipment. The sizes of the objects that need to be subjected to tensile and pressure metrology during use are different, which is not convenient for adjustment. When the equipment is tilted, there will be some deviations in mechanical metrology, and during the process of tensile and pressure metrology during use, two pieces of equipment are required, resulting in higher costs and occupying more space. Therefore, technical personnel in this field have provided an integrated device for high-precision mechanical metrology and automatic calibration to solve the problems raised in the above background technique. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] Aiming at the deficiencies of the existing technology, the present invention provides an integrated device for high-precision mechanical metrology and automatic calibration, which solves the problems that the sizes of the objects that need to be subjected to tensile and pressure metrology during use are different, which is not convenient for adjustment, when the equipment is tilted, there will be some deviations in mechanical metrology, and during the process of tensile and pressure metrology during use, two pieces of equipment are required, resulting in higher costs and occupying more space.

[0006] (2) Technical Solutions

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions: An integrated device for high-precision mechanical metrology and automatic calibration, including a base and a console. The console is arranged on one side of the base. A second storage box is fixedly connected to the center of the upper end surface of the base. A switching structure is provided on the upper end surface of the base at the rear end of the base. Columns are fixedly connected to the upper end surfaces of the base on both sides of the second storage box. The upper ends of the columns are fixedly connected to a top plate. Sliding grooves are opened at the centers of the inner side walls of the two columns. Sliders are arranged inside the two sliding grooves. A lifting structure is provided at the upper center of the interior of the base;

[0008] The lifting structure includes a mounting plate. At the front of one side of the upper end surface of the mounting plate, a servo motor is fixedly connected. The output end of the servo motor is fixedly connected with a driving worm. A driving worm gear is rotatably connected to the upper end surface of the mounting plate at the rear of the driving worm. A first synchronous pulley is fixedly connected to the upper end of the driving worm gear. A second synchronous pulley is rotatably connected to the rear of one side of the upper end surface of the mounting plate. A synchronous belt is arranged outside the second synchronous pulley and the first synchronous pulley. Threaded rods are fixedly connected to the upper end surfaces of the second synchronous pulley and the first synchronous pulley. The upper ends of the two threaded rods respectively penetrate through the upper inner wall of the base and extend into the two chutes, and the ends are respectively rotatably connected to the upper inner walls of the two chutes. The slider is threadedly sleeved outside the two threaded rods. By controlling the servo motor to start, the servo motor drives the driving worm to rotate, the driving worm drives the driving worm gear to rotate, thereby driving the first synchronous pulley to rotate. The first synchronous pulley drives the second synchronous pulley to rotate synchronously through the synchronous belt, so that the two threaded rods rotate synchronously, and the slider moves up and down smoothly, thereby adjusting the position of the first storage box, and there will be no angular inclination, providing accurate position adjustment;

[0009] A hydraulic cylinder is fixedly connected to the center of the upper end surface of the slider. The output end of the hydraulic cylinder penetrates through the slider and extends to the lower end of the slider, and the end is fixedly connected with a first storage box. Extension blocks are fixedly connected to both sides of the lower end of the first storage box. Limiting grooves are respectively opened at the centers of the outer side walls of the two extension blocks. A second base plate is arranged at the lower end of the first storage box.

[0010] Preferably, a horizontal adjustment structure is fixedly connected to the lower end surface of the base. The horizontal adjustment structure includes a base. A support rod is fixedly connected to the center of the upper end surface of the base. A first sphere is fixedly connected to the center of the upper end surface of the support rod. A top seat is sleeved on the upper part outside the first sphere. Second spheres are rotatably connected to the four diagonals of the upper end surface of the base. First electric telescopic rods are fixedly connected to the upper end surfaces of the four second spheres. The output ends of the four first electric telescopic rods are fixedly connected with third spheres. The third spheres are respectively rotatably connected to the four diagonals of the lower end surface of the top seat. A two-dimensional ultra-precision digital inclinometer sensor is arranged at one side of the center of the lower end surface of the top seat. By monitoring the level of the top seat in real time through the two-dimensional ultra-precision digital inclinometer sensor, and sending electromagnetic wave signals to the console in real time, the console then controls the four first electric telescopic rods to extend and contract correspondingly, so that the top seat rotates along the first sphere, thereby adjusting the level of the top seat, and more accurate data can be provided during the experiment.

[0011] Preferably, the switching structure includes a vertical plate. A second electric telescopic rod is fixedly connected to the upper part of the center of the rear end surface of the vertical plate. The output end of the second electric telescopic rod penetrates through the front end surface of the vertical plate and extends to the front of the vertical plate, and the end is fixedly connected with a shell. Slide rails are fixedly connected to both sides of the lower part of the front end surface of the vertical plate. A first base plate is arranged on the upper end surface of the shell;

[0012] A pressure sensor is fixedly connected to the center of the lower end face of the second substrate and the center of the upper end face of the housing. A bottom plate is provided on the lower end face of the second substrate. By controlling the extension of the second electric telescopic rod, the second electric telescopic rod pushes the housing to move forward along the two slide rails, and then the pressure is measured by the two pressure sensors.

[0013] Preferably, a tension sensor is fixedly connected to the center of the inner wall of the upper part of the first storage box and the center of the inner wall of the lower part of the second storage box. Hooks are fixedly connected to the center of the lower end face of the upper tension sensor and the center of the upper end face of the lower tension sensor. An object to be measured for tension is hung by the two hooks, and the tension is measured by the two tension sensors.

[0014] Preferably, limiting blocks are fixedly connected to both side walls of the second substrate. The two limiting blocks are respectively slidably connected inside the two limiting grooves. Limiting bolts are provided at the front center of one side wall of the two extension blocks. The two limiting bolts respectively penetrate one side wall of the two limiting blocks, and the ends are respectively threadedly connected to both side walls of the two extension blocks, so that it is convenient to insert the two limiting blocks into the two limiting grooves and fix the two limiting blocks by the two limiting bolts to improve stability.

[0015] (III) Beneficial effects

[0016] The present invention provides an integrated device for high-precision mechanical measurement and automatic calibration. It has the following

[0017] Beneficial effects:

[0018] 1. In the present invention, the levelness of the top seat is monitored in real time by the two-dimensional ultra-precision digital inclinometer sensor, and electromagnetic wave signals are sent to the console in real time. The console then controls the four first electric telescopic rods to extend and contract accordingly, so that the top seat rotates along the first sphere, thereby adjusting the level of the top seat and providing more accurate data during the experiment.

[0019] 2. In the present invention, when measuring pressure, by controlling the extension of the second electric telescopic rod, the second electric telescopic rod pushes the housing to move forward along the two slide rails. By controlling the extension of the hydraulic cylinder, the bottom plate is pushed downward to squeeze the object on the upper end of the first substrate for pressure measurement. When tensile testing is required, the two limiting bolts are rotated in the reverse direction, the second substrate is pulled out forward, the second electric telescopic rod is controlled to contract, the housing moves backward along the two slide rails, the two hooks are exposed, the object to be tested is hung on the two hooks, and the tension is measured by the two tension sensors, which is convenient for switching and reduces the floor area and the use of the equipment.

[0020] 3. In the present invention, when measuring the tensile and compressive forces of objects of different sizes, the servo motor is started by control. The servo motor drives the transmission worm to rotate, the transmission worm drives the transmission worm gear to rotate, thereby driving the first synchronous pulley to rotate. The first synchronous pulley drives the second synchronous pulley to rotate synchronously through the synchronous belt, so that the two lead screws rotate synchronously, enabling the slider to move up and down smoothly, thereby adjusting the position of the first storage box without angular tilt and providing precise position adjustment.

[0021] 4. In the present invention, through the large reduction ratio between the transmission worm and the transmission worm gear, the use of a speed reducer is reduced, the structure is simpler, which is convenient for subsequent maintenance. Moreover, there is a self-locking property between the transmission worm and the transmission worm gear, preventing the two lead screws from rotating during the measurement process, thus avoiding the problem of measurement deviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view of the present invention;

[0023] Figure 2 is a front cross-sectional view of the present invention;

[0024] Figure 3 is a perspective view of another perspective of the switching structure of the present invention;

[0025] Figure 4 is a perspective view of the lifting structure of the present invention;

[0026] Figure 5 is a perspective view of the second storage box of the present invention;

[0027] Figure 6 is a front cross-sectional view of the second storage box of the present invention.

[0028] Wherein, 1. Base; 2. Horizontal adjustment structure; 201. Base plate; 202. Support rod; 203. First sphere; 204. Top seat; 205. Second sphere; 206. First electric telescopic rod; 207. Third sphere; 208. Two-dimensional ultra-precision digital inclinometer sensor; 3. Column; 4. Switching structure; 401. Vertical plate; 402. Second electric telescopic rod; 403. Slide rail; 404. Housing; 405. First substrate; 5. Top plate; 6. Hydraulic cylinder; 7. Slide block; 8. First storage box; 9. Console; 10. Lifting structure; 1001. Mounting plate; 1002. Servo motor; 1003. Transmission worm; 1004. Transmission worm gear; 1005. First synchronous pulley; 1006. Second synchronous pulley; 1007. Synchronous belt; 1008. Lead screw; 11. Second storage box; 12. Tensile force sensor; 13. Hook; 14. Chute; 15. Bottom plate; 16. Limit block; 17. Limit bolt; 18. Limit groove; 19. Extension block; 20. Second substrate; 21. Pressure sensor. DETAILED DESCRIPTION OF THE INVENTION

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0030] Embodiment 1:

[0031] As Figure 1-6 shown, the embodiment of the present invention provides an integrated device for high-precision mechanical measurement and automatic calibration, including a base 1 and a console 9. The console 9 is arranged on one side of the base 1. At the center of the upper end surface of the base 1, a second storage box 11 is fixedly connected. On the upper end surface of the base 1 at the rear end of the base 1, a switching structure 4 is provided. On the upper end surfaces of the base 1 on both sides of the second storage box 11, columns 3 are fixedly connected. At the upper ends of the columns 3, a top plate 5 is fixedly connected. At the centers of the inner side walls of the two columns 3, sliding grooves 14 are provided. Inside the two sliding grooves 14, sliders 7 are provided. At the upper center of the interior of the base 1, a lifting structure 10 is provided. By adjusting the height of the slider 7 through the lifting structure 10, it is convenient to measure objects of different sizes.

[0032] The lifting structure 10 includes a mounting plate 1001. At the front of one side of the upper end surface of the mounting plate 1001, a servo motor 1002 is fixedly connected. The output end of the servo motor 1002 is fixedly connected with a driving worm 1003. At the rear end of the driving worm 1003 on the upper end surface of the mounting plate 1001, a driving worm gear 1004 is rotatably connected. At the upper end of the driving worm gear 1004, a first synchronous wheel 1005 is fixedly connected. At the rear of one side of the upper end surface of the mounting plate 1001, a second synchronous wheel 1006 is rotatably connected. A synchronous belt 1007 is provided outside the second synchronous wheel 1006 and the first synchronous wheel 1005. On the upper end surfaces of the second synchronous wheel 1006 and the first synchronous wheel 1005, lead screws 1008 are fixedly connected. The upper ends of the two lead screws 1008 respectively penetrate through the upper inner wall of the base 1 and extend into the two sliding grooves 14, and the ends are respectively rotatably connected to the upper inner walls of the two sliding grooves 14. The slider 7 is threadedly sleeved outside the two lead screws 1008. By controlling the servo motor 1002 to start, the servo motor 1002 drives the driving worm 1003 to rotate, the driving worm 1003 drives the driving worm gear 1004 to rotate, thereby driving the first synchronous wheel 1005 to rotate. The first synchronous wheel 1005 drives the second synchronous wheel 1006 to rotate synchronously through the synchronous belt 1007, so that the two lead screws 1008 rotate synchronously, and the slider 7 moves up and down smoothly, thereby adjusting the position of the first storage box 8, and there will be no angular inclination, providing precise position adjustment;

[0033] At the center of the upper end face of the slider 7, a hydraulic cylinder 6 is fixedly connected. The output end of the hydraulic cylinder 6 penetrates through the slider 7 to the lower end of the slider 7, and the end is fixedly connected with a first storage box 8. At both sides near the lower end of the first storage box 8, extension blocks 19 are fixedly connected. At the center of the outer side wall of the two extension blocks 19, limiting grooves 18 are provided. A second substrate 20 is provided at the lower end of the first storage box 8. By pushing the first storage box 8 up and down through the hydraulic cylinder 6, it is convenient to carry out pressure measurement.

[0034] As Figure 2 shown, a horizontal adjustment structure 2 is fixedly connected to the lower end face of the base 1. The horizontal adjustment structure 2 includes a base 201. At the center of the upper end face of the base 201, a support rod 202 is fixedly connected. At the center of the upper end face of the support rod 202, a first sphere 203 is fixedly connected. A top seat 204 is sleeved on the upper part outside the first sphere 203. At the four diagonal corners of the upper end face of the base 201, second spheres 205 are rotatably connected. On the upper end faces of the four second spheres 205, first electric telescopic rods 206 are fixedly connected. The output ends of the four first electric telescopic rods 206 are fixedly connected with third spheres 207. The third spheres 207 are respectively rotatably connected to the four diagonal corners of the lower end face of the top seat 204. A two-dimensional ultra-precision digital inclinometer 208 is provided at one side near the center of the lower end face of the top seat 204. By monitoring the level of the top seat 204 in real time through the two-dimensional ultra-precision digital inclinometer 208, and by sending electromagnetic wave signals to the console 9 in real time, the console 9 then controls the four first electric telescopic rods 206 to extend and contract correspondingly, so that the top seat 204 rotates along the first sphere 203, thereby adjusting the level of the top seat 204 and providing more accurate data during the experiment.

[0035] As Figure 3 shown, the switching structure 4 includes a vertical plate 401. At the upper part near the center of the rear end face of the vertical plate 401, a second electric telescopic rod 402 is fixedly connected. The output end of the second electric telescopic rod 402 penetrates through the front end face of the vertical plate 401 to the front of the vertical plate 401, and the end is fixedly connected with a housing 404. At both sides near the lower part of the front end face of the vertical plate 401, slide rails 403 are fixedly connected. A first substrate 405 is provided on the upper end face of the housing 404. By controlling the extension of the second electric telescopic rod 402, the second electric telescopic rod 402 pushes the housing 404 to move forward along the two slide rails 403.

[0036] At the center of the lower end face of the second substrate 20 and the center of the upper end face of the housing 404, pressure sensors 21 are fixedly connected. A bottom plate 15 is provided on the lower end face of the second substrate 20. Then, pressure measurement is carried out through the two pressure sensors 21.

[0037] At the center of the inner wall of the upper part of the first storage box 8 and the center of the inner wall of the lower part of the second storage box 11, a tension sensor 12 is fixedly connected. At the center of the lower end surface of the upper tension sensor 12 and the center of the upper end surface of the lower tension sensor 12, a hook 13 is fixedly connected. The object to be measured for tension is hung by the two hooks 13, and the tension is measured by the two tension sensors 12.

[0038] On both side walls of the second substrate 20, a limit block 16 is fixedly connected. The two limit blocks 16 are respectively slidably connected inside the two limit slots 18. At the front of the center of one side wall of the two extension blocks 19, a limit bolt 17 is provided. The two limit bolts 17 respectively penetrate one side wall of the two limit blocks 16, and the ends are respectively threadedly connected to both side walls of the two extension blocks 19, which is convenient for inserting the two limit blocks 16 into the two limit slots 18, and fixing the two limit blocks 16 by the two limit bolts 17 to improve stability.

[0039] Working principle: During the use process, the two-dimensional ultra-precision digital inclinometer sensor 208 monitors the levelness of the top seat 204 in real time. By sending electromagnetic wave signals to the console 9 in real time, the console 9 then controls the four first electric telescopic rods 206 to extend and contract accordingly, so that the top seat 204 rotates along the first sphere 203, thereby adjusting the levelness of the top seat 204 and providing more accurate data during the experiment.

[0040] When performing pressure measurement, by controlling the second electric telescopic rod 402 to extend, the second electric telescopic rod 402 pushes the housing 404 to move forward along the two slide rails 403. By controlling the hydraulic cylinder 6 to extend, the bottom plate 15 is pushed downward to squeeze the object on the upper end of the first substrate 405 for pressure measurement. When a tensile test is required, the two limit bolts 17 are rotated in the reverse direction, the second substrate 20 is pulled out forward, the second electric telescopic rod 402 is controlled to contract, so that the housing 404 moves backward along the two slide rails 403, the two hooks 13 are exposed, the object to be tested is hung on the two hooks 13, and the tension is measured by the two tension sensors 12, which is convenient for switching and reduces the floor area and the use of equipment.

[0041] When measuring the tension and pressure of objects of different sizes, by controlling the servo motor 1002 to start, the servo motor 1002 drives the transmission worm 1003 to rotate, the transmission worm 1003 drives the transmission worm wheel 1004 to rotate, thereby driving the first synchronous wheel 1005 to rotate. The first synchronous wheel 1005 drives the second synchronous wheel 1006 to rotate synchronously through the synchronous belt 1007, so that the two lead screws 1008 rotate synchronously, and the slider 7 moves up and down smoothly, thereby adjusting the position of the first storage box 8 without angular inclination and providing accurate position adjustment.

[0042] Furthermore, with the large reduction ratio between the driving worm 1003 and the driving worm wheel 1004, the use of the speed reducer is reduced, the structure is simpler, which is convenient for subsequent maintenance. Moreover, there is a self-locking property between the driving worm 1003 and the driving worm wheel 1004, preventing the two lead screws 1008 from rotating during the metering process, thus avoiding the problem of metering deviation.

[0043] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An integrated device for high-precision mechanical metrology and automatic calibration, comprising a base (1) and a control console (9), wherein the control console (9) is arranged on one side of the base (1), characterized in that: A second storage box (11) is fixedly connected at the center of the upper end surface of the base (1); a switching structure (4) is provided on the upper end surface of the base (1) at the rear end of the base (1); columns (3) are fixedly connected to the upper end surfaces of the bases (1) on both sides of the second storage box (11); a top plate (5) is fixedly connected to the upper end of the column (3); a slide groove (14) is provided at the center of the inner side wall of the two columns (3); a slider (7) is provided inside the two slide grooves (14); and a lifting structure (10) is provided at the upper center of the base (1); The lifting structure (10) comprises a mounting plate (1001), a servo motor (1002) is fixedly connected to the front of one side of the upper end surface of the mounting plate (1001), a transmission worm (1003) is fixedly connected to the output end of the servo motor (1002), a transmission worm wheel (1004) is rotatably connected to the upper end surface of the mounting plate (1001) at the rear end of the transmission worm wheel (1003), a first synchronous wheel (1005) is fixedly connected to the upper end of the transmission worm wheel (1004), and a servo motor (1002) is fixedly connected to the output end of the servo motor (1002). A second synchronous wheel (1006) is connected, and a synchronous belt (1007) is provided on the outer side of the second synchronous wheel (1006) and the first synchronous wheel (1005). The upper end surfaces of the second synchronous wheel (1006) and the first synchronous wheel (1005) are fixedly connected with screw rods (1008), and the upper ends of the two screw rods (1008) respectively penetrate the upper inner wall of the base (1) and pass into the two slide grooves (14), and the ends are respectively rotatably connected to the upper inner walls of the two slide grooves (14), and the slider (7) is threadedly sleeved on the outer sides of the two screw rods (1008); A hydraulic cylinder (6) is fixedly connected at the center of the upper end surface of the slider (7); the output end of the hydraulic cylinder (6) passes through the slider (7) to the lower end of the slider (7), and the end is fixedly connected to a first storage box (8); extension blocks (19) are fixedly connected at both sides of the lower end of the first storage box (8); limiting grooves (18) are provided at the center of the outer side walls of the two extension blocks (19); and a second base plate (20) is provided at the lower end of the first storage box (8).

2. The integrated device for high-precision mechanical metrology and automatic calibration according to claim 1, characterized in that: A horizontal adjustment structure (2) is fixedly connected to the lower end surface of the base (1), and the horizontal adjustment structure (2) comprises a base (201), a support rod (202) is fixedly connected to the center of the upper end surface of the base (201), a first sphere (203) is fixedly connected to the center of the upper end surface of the support rod (202), a top seat (204) is sleeved on the upper outer side of the first sphere (203), second spheres (205) are rotatably connected to the four diagonal points of the upper end surface of the base (201), first electric telescopic rods (206) are fixedly connected to the upper end surfaces of the four second spheres (205), third spheres (207) are fixedly connected to the output ends of the four first electric telescopic rods (206), and the third spheres (207) are rotatably connected to the four diagonal points of the lower end surface of the top seat (204), and a two-dimensional ultra-precision digital inclinometer sensor (208) is provided at one side of the center of the lower end surface of the top seat (204).

3. The integrated device for high-precision mechanical metrology and automatic calibration according to claim 1, characterized in that: The switching structure (4) comprises a vertical plate (401), a second electric telescopic rod (402) is fixedly connected to the center of the rear end surface of the vertical plate (401) at the upper part, the output end of the second electric telescopic rod (402) passes through the front end surface of the vertical plate (401) and reaches the front end of the vertical plate (401), and the end is fixedly connected to a shell (404), both sides of the front end surface of the vertical plate (401) are fixedly connected to the lower part of the slide rail (403), and the upper end surface of the shell (404) is provided with a first base plate (405); A pressure sensor (21) is fixedly connected at the center of the lower end surface of the second substrate (20) and the center of the upper end surface of the shell (404), and a bottom plate (15) is provided on the lower end surface of the second substrate (20).

4. The integrated device for high-precision mechanical metrology and automatic calibration according to claim 1, characterized in that: A tension sensor (12) is fixedly connected at the center of the upper inner wall of the first storage box (8) and at the center of the lower inner wall of the second storage box (11), and a hook (13) is fixedly connected at the center of the lower end surface of the tension sensor (12) at the upper side and at the center of the upper end surface of the tension sensor (12) at the lower side.

5. The integrated device for high-precision mechanical metrology and automatic calibration according to claim 1, characterized in that: Limiting blocks (16) are fixedly connected to both side walls of the second base plate (20), and the two limiting blocks (16) are respectively slidably connected inside the two limiting grooves (18). Limiting bolts (17) are respectively provided at the front center of one side wall of the two extension blocks (19), and the two limiting bolts (17) respectively penetrate one side wall of the two limiting blocks (16), and the ends are respectively threadedly connected to the two side walls of the two extension blocks (19).

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