A method for preparing a precision welded tube for a cylinder of an automobile shock absorber

Abstract

The application discloses a preparation method of a precision welded pipe for a cylinder of an automobile shock absorber, and belongs to the technical field of shock absorber manufacturing. The method comprises the following steps: after a steel plate is longitudinally sheared into a strip through pretreatment, the strip is wound; the two ends of the wound strip are butt welded to form a pipe blank; burrs at the edge of the weld of the pipe blank are removed; the inner and outer sides of the pipe blank are roughly turned with the outer circle of the pipe blank as a reference; after rough turning, the inner and outer sides of the pipe blank are finely turned with the inner wall of the pipe blank as a reference; the inner wall of the finely turned pipe blank is ground; and finally, the welded pipe after grinding is post-processed. The inner wall of the welded pipe is ground by a grinding wheel, and the outer wall of the welded pipe is supported by a supporting wheel during grinding. The welded pipe can rotate during the grinding process to complete grinding in the whole circumferential direction. The rotating directions of the grinding wheel and the supporting wheel are opposite to the rotating direction of the welded pipe. The method can reduce the deformation of the welded pipe during the equipment process and ensure the machining precision.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of shock absorber manufacturing, and particularly relates to a preparation method of a precision welded pipe for a cylinder of an automobile shock absorber. BACKGROUND

[0002] In order to improve the driving comfort of an automobile, a shock absorber is installed in the suspension system of most automobiles. The manufacturing precision and product quality of the shock absorber are directly related to driving safety. The welded pipe is subjected to a large stress during driving, and therefore, detection of the welded pipe before leaving the factory is particularly important. A working piston of the shock absorber repeatedly moves in the cylinder, and the friction force of the inner wall of the cylinder seriously affects the service life and use effect of the shock absorber. If the friction force is too large, the wear of the working piston increases, the resistance of the shock absorber increases, and the damping effect and service life of the device are affected. The existing cylinder welded pipe is usually formed by winding and welding a steel plate. In order to ensure the surface roughness of the inner wall of the welded pipe, the inner wall of the welded pipe usually needs to be finished. Due to the existing process defects, the welded pipe is prone to deformation during finishing, and the yield rate is low. SUMMARY

[0003] Therefore, the purpose of the present application is to provide a preparation method of a precision welded pipe for a cylinder of an automobile shock absorber, which can reduce the deformation of the welded pipe during processing and ensure the processing precision.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0005] The present application provides a preparation method of a precision welded pipe for a cylinder of an automobile shock absorber. The method cuts a pretreated steel plate into a strip by longitudinal longitudinal shearing, winds the steel plate, butt welds the two ends of the wound steel plate to form a pipe blank, removes burrs at the edge of the weld of the pipe blank, rough turns the inner and outer sides of the pipe blank with the outer circle of the pipe blank as a reference, and finishes the inner and outer sides of the pipe blank with the inner wall of the pipe blank as a reference after rough turning. The inner wall of the finished pipe blank is ground, and the welded pipe after grinding is finally post-processed. In the grinding process, the inner wall of the welded pipe is ground by a grinding wheel, and the grinding position is supported by a supporting wheel on the outer wall of the welded pipe. The welded pipe can rotate to complete grinding in the entire circumferential direction during the grinding process. The rotation directions of the grinding wheel and the supporting wheel are opposite to the rotation direction of the welded pipe.

[0006] Further, the grinding wheel and the supporting wheel can simultaneously approach or move away from the processing wall surface of the welded pipe, and the grinding wheel and the supporting wheel can simultaneously displace along the axial direction of the welded pipe and the displacements of the two are synchronous.

[0007] Further, the grinding wheel and the supporting wheel are synchronously controlled by a welded pipe preparation device, the welded pipe preparation device comprises a first transmission rod connected with the grinding wheel, a second transmission rod connected with the first transmission rod through a first spherical hinge joint, and a first spur gear coaxially connected with the second transmission rod, the welded pipe preparation device further comprises a third transmission rod connected with the supporting wheel, a fourth transmission rod connected with the third transmission rod through a second spherical hinge joint, and a second spur gear coaxially connected with the fourth transmission rod, the first spur gear and the second spur gear are simultaneously meshed with a third spur gear, and the third spur gear is driven to rotate by a first motor.

[0008] Further, the first transmission rod and the third transmission rod are of the same structure, the first transmission rod comprises a vertical outer rod, a vertical inner rod slidingly arranged in the vertical outer rod, and a spring connecting the vertical outer rod and the vertical inner rod, the vertical outer rod is fixedly connected with the grinding wheel or the supporting wheel, the outer side of the vertical inner rod is provided with a sliding rod, and the outer side of the vertical outer rod is provided with a sliding groove matched with the sliding rod.

[0009] Further, the outer side of the vertical inner rod is rotationally matched with a moving block, a guide rod is slidingly arranged in the moving block, the guide rod is fixedly connected with a support plate, the moving block is further threadedly connected with a screw rod, the thread directions of the two moving blocks are opposite, the screw rod is connected with a first bevel gear, the first bevel gear is meshed with a second bevel gear, the second bevel gear is coaxially connected with a rotating shaft, the rotating shaft is connected to the output end of a second motor, the second motor is fixedly connected with a support base, and the support plate is fixed on the upper side of the support base.

[0010] Further, a rotating sleeve is rotationally arranged on the vertical outer rod, the two ends of the rotating sleeve are axially limited by upper and lower limiting plates, and the upper and lower limiting plates are fixedly separated on the vertical outer rod; the outer side of the rotating sleeve on the first transmission rod is fixedly connected with a horizontal outer rod, the outer side of the rotating sleeve on the third transmission rod is fixedly connected to one end of a horizontal inner rod, and the other end of the horizontal inner rod is slidingly arranged in the horizontal outer rod.

[0011] Further, a sliding plate is arranged on the support base, and the sliding plate is connected to a rotating support table through an extension device.

[0012] Further, the sliding plate is slidingly arranged on the support base, first and second horizontal limiting plates are arranged on the two sides of the sliding plate, a limiting groove for limiting the sliding plate is formed between the first and second horizontal limiting plates, the first and second horizontal limiting plates are simultaneously connected to a limiting block through L-shaped supports, an arc-shaped groove is arranged on one side of the limiting block, and the arc-shaped groove is used for limiting the radial direction of the welded pipe.

[0013] Further, the back side of the limiting block is connected with a rack through a supporting block, a transverse opening slot for matching the supporting block is formed on the support, the rack is engaged with a gear, the gear is controlled to rotate through a third motor, and the third motor is fixed on the support.

[0014] Further, the support comprises a lower support and an upper support, the upper end of the lower support is provided with a lower connecting plate, the lower end of the upper support is provided with an upper connecting plate, upper and lower longitudinal opening slots are respectively formed on the upper and lower connecting plates, and the upper and lower supports are fixed through bolts.

[0015] The present application has the advantages that:

[0016] The present application discloses a preparation method of a precision welded pipe for a cylinder of an automobile shock absorber.

[0017] In the preparation method, the unique welded pipe preparation equipment is adopted to support the grinding part on the outer wall of the welded pipe through a supporting wheel while the inner wall of the welded pipe is ground by a grinding wheel, so that the pressure deformation problem of the thin wall of the welded pipe at the grinding part is reduced, and the processing quality of the welded pipe is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to make the purpose, technical scheme and beneficial effects of the present application clearer, the present application provides the following drawings for illustration:

[0019] Figure 1 It is a flowchart of the preparation method of the welded pipe;

[0020] Figure 2 It is a structural schematic diagram of the welded pipe preparation equipment Figure 1 ;

[0021] Figure 3 It is a structural schematic diagram of the welded pipe preparation equipment Figure 2 ;

[0022] Figure 4 It is Figure 3 An enlarged view at A;

[0023] Figure 5 It is a schematic diagram of the transmission connection of the grinding wheel and the supporting wheel;

[0024] Figure 6 It is a structural schematic diagram of the first transmission rod;

[0025] Figure 7This is a diagram showing the connection of the skateboard.

[0026] The components in the attached diagram are labeled as follows: 1. Welded pipe; 2. Grinding wheel; 3. Support wheel; 4. First transmission rod; 5. First ball joint; 6. Second transmission rod; 7. First spur gear; 8. Third transmission rod; 9. Second ball joint; 10. Fourth transmission rod; 11. Second spur gear; 12. Third spur gear; 13. First motor; 14. Vertical outer rod; 15. Vertical inner rod; 16. Spring; 17. Slide rod; 18. Slide groove; 19. Moving block; 20. Guide rod; 21. Support plate; 22. Screw; 23. First bevel gear; 24. Second bevel gear; 25. Rotating shaft. Second motor 26, rotating sleeve 27, upper limit plate 28, lower limit plate 29, transverse outer rod 30, transverse inner rod 31, sliding plate 32, telescopic device 33, rotating support platform 34, first transverse limit plate 35, second transverse limit plate 36, L-shaped bracket 37, limit block 38, arc groove 39, support block 40, rack 41, support 42, transverse opening slot 43, gear 44, third motor 45, lower support 46, upper support 47, lower connecting plate 48, upper connecting plate 49, bolt 50. Detailed Implementation

[0027] like Figure 1 As shown, this invention discloses a method for manufacturing precision welded pipes for automotive shock absorber cylinders. The method involves cold rolling a formed steel plate to reduce its thickness to at least half of its original thickness. The pre-treated steel plate is then longitudinally cut into strips of a predetermined width and wound up using a steel plate coiling machine. The two ends of the coiled steel plate are butt-welded to form a pipe blank. Burrs at the weld edges of the pipe blank are removed. After flaw detection confirms no issues, the pipe blank is straightened. Following straightening, further processing operations such as removing excess material from the pipe blank are performed.

[0028] Specifically, when removing excess material from the tube blank, the outer circle of the tube blank is first used as a reference to perform rough turning on the inner and outer sides of the tube blank. After rough turning, the inner wall of the tube blank is used as a reference to perform finish turning on the inner and outer sides of the tube blank. The inner wall of the finished tube blank is then ground. Finally, the welded pipe 1 after grinding is subjected to post-processing. During the grinding process, the inner wall of the welded pipe 1 is ground by the grinding wheel 2, while the part being ground is supported on the outer wall of the welded pipe 1 by the support wheel 3. The welded pipe 1 can rotate during the grinding process to complete the grinding in the entire circumferential direction. The rotation direction of the grinding wheel 2 and the support wheel 3 is opposite to the rotation direction of the welded pipe 1. By rotating the welded pipe 1 during grinding, the entire circumference of the welded pipe 1 can be processed. The specific rotational driving force of the welded pipe 1 can be driven by the friction of the grinding wheel 2. However, due to the damping effect of the rotating fixture corresponding to the welded pipe 1, the rotational speeds of the two are not synchronized, and the rotational speed of the welded pipe 1 is much lower than the rotational speed of the grinding wheel 2, so as to ensure the necessary grinding effect.

[0029] The method of the present application can remove part of the excess allowance of the welded pipe 1 before grinding, so as to reduce the pressure of the welded pipe 1 during grinding, prevent the problems of excessive grinding of the surface of the welded pipe 1 and grinding deformation caused by long-term grinding temperature rise, etc.

[0030] In the embodiment, the grinding wheel 2 and the support wheel 3 can approach or move away from the machined wall surface of the welded pipe 1 at the same time, the diameter of the grinding wheel 2 is smaller than the inner diameter of the welded pipe 1, that is, when the grinding wheel 2 grinds the inner wall of the welded pipe 1, the outer wall corresponding to the position is supported by the support wheel 3 to resist the force of the grinding wheel 2, so as to reduce the grinding deformation of the welded pipe 1. The support wheel 3 of the present application is supported by a steel material with hard texture and smooth surface, which can reduce the damage to the welded pipe 1 as much as possible. Under certain conditions, because the welded pipe 1 is extruded by the grinding wheel 2 and the support wheel 3 during grinding, the welded pipe 1 can achieve the effect of hot rolling, so that the pipe wall of the welded pipe 1 can be hot rolled and plastic, which can improve the processing performance of the metal and alloy, that is, the coarse grains in the casting state are broken, the casting defects are reduced or eliminated, the casting structure is changed into deformed structure, so as to improve the processing performance of the welded pipe 1 and make the subsequent grinding process more smooth. The grinding wheel 2 and the support wheel 3 can simultaneously displace along the axial direction of the welded pipe 1 and the displacement of the two is synchronous, which can adjust the circumferential grinding position according to the needs, so that the grinding and supporting can be synchronized, and the grinding process can be smoothly carried out.

[0031] In the embodiment, the grinding wheel 2 and the support wheel 3 are synchronously controlled by the welded pipe preparation equipment, which simplifies the structure of the equipment and achieves the consistency of processing. Specifically, as shown in Figures 2 to 7As shown, the welded pipe preparation device comprises a first transmission rod 4 connected with the grinding wheel 2, a second transmission rod 6 connected with the first transmission rod 4 through a first spherical hinge joint 5, and a first spur gear 7 coaxially connected with the second transmission rod 6. The first transmission rod 4 is vertically arranged, the lower end of the first transmission rod 4 is connected to the grinding wheel 2, the upper end of the first transmission rod 4 is connected to the second transmission rod 6 through the first spherical hinge joint 5, and the second transmission rod 6 is rotationally connected with the support plate 21 on the upper side of the support 42. The welded pipe preparation device further comprises a third transmission rod 8 connected with the support wheel 3, a fourth transmission rod 10 connected with the third transmission rod 8 through a second spherical hinge joint 9, and a second spur gear 11 coaxially connected with the fourth transmission rod 10. The support wheel 3 is coaxially connected with the third transmission rod 8 in a similar manner as the grinding wheel 2 is connected with the first transmission rod 4, the first spur gear 7 and the second spur gear 11 are simultaneously meshed with a third spur gear 12, and the third spur gear 12 is driven to rotate by a first motor 13. The control mode is specifically that the first motor 13 drives the third spur gear 12 to rotate, and the third spur gear 12 can simultaneously drive the first spur gear 7 and the second spur gear 11 to rotate in the same direction. In this way, the grinding wheel 2 and the support wheel 3, which are respectively transmissionally connected with the first spur gear 7 and the second spur gear 11, can rotate in the same direction, the grinding wheel 2 can grind the inner wall of the welded pipe 1, and the support wheel 3 can support.

[0032] In the embodiment, the first transmission rod 4 and the third transmission rod 8 have the same structure, and the first transmission rod 4 is taken as an example. The first transmission rod 4 comprises a vertical outer rod 14, a vertical inner rod 15 slidably arranged in the vertical outer rod 14, and a spring 16 connecting the vertical outer rod 14 and the vertical inner rod 15. The lower end of the vertical outer rod 14 is fixedly connected with the grinding wheel 2 or the support wheel 3, the upper end of the vertical inner rod 15 is connected with the first spherical hinge joint 5, the lower end of the vertical inner rod 15 is slidably inserted into the vertical outer rod 14, and the bottom of the vertical outer rod 14 and the lower end of the vertical inner rod 15 are further connected with the spring 16. The outer side of the vertical inner rod 15 is provided with a sliding rod 17, and the outer side of the vertical outer rod 14 is provided with a sliding groove 18 matched with the sliding rod 17. By arranging the sliding rod 17, the vertical inner rod 15 can drive the vertical outer rod 14 and the grinding wheel 2 connected with the outer side of the vertical outer rod 14 to rotate, so as to achieve the purpose of transmission. In the figure, the position of the sliding rod 17 is at the upper limit position, and the sliding rod 17 is located in the middle of the sliding groove 18 when the spring 16 is not in action, which can be understood by those skilled in the art. By adopting the elastic connection between the vertical inner rod 15 and the vertical outer rod 14, the friction in the axial direction can be buffered, and the damage to the welded pipe 1 caused by the instantaneous friction after the axial movement of the welded pipe 1 can be reduced.

[0033] In this embodiment, a movable block 19 is rotatably fitted on the outer side of the vertical inner rod 15. The movable block 19 is square in shape, and through holes and threaded holes are opened on the left and right sides of the movable block 19. The through holes are fitted with the guide rod 20. The guide rod 20 is slidably inserted inside the movable block 19. The guide rod 20 is fixedly connected to the support plate 21. The movable block 19 is also threadedly connected to a screw 22. The screw 22 is fitted with the threaded hole. The threads of the two movable blocks 19 are in opposite directions. The screw 22 is connected to a first bevel gear 23. The first bevel gear 23 meshes with a second bevel gear 24. The second bevel gear 24 is coaxially connected to a rotating shaft 25. The rotating shaft 25 is connected to the output end of the second motor 26. The second motor 26 is fixedly connected to the support 42. The support plate 21 is fixed on the upper side of the support 42. By setting the screw 22, the control method of the moving block 19 when the screw 22 rotates is relative, that is, the two moving blocks 19 are either relatively close or relatively separated. By controlling the screw 22, the gap between the grinding wheel 2 and the support wheel 3 can be adjusted to adjust the grinding amount of the grinding wheel 2 and the support degree of the support wheel 3.

[0034] In this embodiment, a rotating sleeve 27 is rotatably mounted on the vertical outer rod 14. The two ends of the rotating sleeve 27 are axially limited by an upper limit plate 28 and a lower limit plate 29, which are fixedly spaced on the vertical outer rod 14. A transverse outer rod 30 is fixed to the outer side of the rotating sleeve 27 on the first transmission rod 4, and the outer side of the rotating sleeve 27 on the third transmission rod 8 is fixed to one end of the transverse inner rod 31. The other end of the transverse inner rod 31 is slidably mounted within the transverse outer rod 30. By providing the rotating sleeve 27, the vertical outer rods 14 on the first transmission rod 4 and the third transmission rod 8 can move synchronously in the axial direction, thus allowing the grinding wheel 2 and the support wheel 3 to move synchronously.

[0035] In the embodiment, the support 42 is provided with a sliding plate 32, the sliding plate 32 is connected to a rotating support table 34 through an extension device 33, and two ends of the extension device 33 are connected to the sliding plate 32 and the rotating support table 34, respectively. The extension device 33 can adopt a hydraulic cylinder or an air cylinder or a linear motor, and the hydraulic cylinder is adopted in the application. One end of the hydraulic cylinder is connected to the sliding plate 32, and the other end is connected to the rotating support table 34, so as to drive the rotating support table 34 to displace upward and downward to control the height of grinding. Specifically, in the embodiment of the application, the sliding plate 32 is slidingly arranged on the support 42, and the sliding plate 32 is provided with a first transverse limiting plate 35 and a second transverse limiting plate 36 on two sides. The first transverse limiting plate 35 and the second transverse limiting plate 36 are arranged in parallel and are fixed through an L-shaped support 37. A limiting groove for limiting the sliding plate 32 is formed between the first transverse limiting plate 35 and the second transverse limiting plate 36, and the limiting groove is arranged along the transverse direction. Therefore, the sliding plate 32 can move along the transverse direction under the action of force. The first transverse limiting plate 35 and the second transverse limiting plate 36 are connected to a limiting block 38 through the L-shaped support 37. An arc-shaped groove 39 is formed on one side of the limiting block 38, and the arc-shaped groove 39 is used for limiting the radial direction of the welded pipe 1.

[0036] In the embodiment, the back side of the limiting block 38 is connected with a rack 41 through a supporting block 40, a transverse opening groove 43 for cooperating with the supporting block 40 is formed on the support 42, the rack 41 is engaged with a gear 44, the gear 44 is controlled to rotate through a third motor 45, and the third motor 45 is fixed on the support 42. When the third motor 45 drives the gear 44 to rotate, the gear 44 can drive the rack 41 to displace along the transverse direction, the rack 41 drives the limiting block 38 and the welded pipe 1 to displace along the transverse direction through the supporting block 40, and the adjustment of the transverse position of the welded pipe 1 can be realized.

[0037] In the embodiment, the support 42 includes a lower support 46 and an upper support 47. The upper end of the lower support 46 is provided with a lower connecting plate 48, and the lower end of the upper support 47 is provided with an upper connecting plate 49. An upper longitudinal opening groove and a lower longitudinal opening groove are respectively formed on the upper connecting plate 49 and the lower connecting plate 48, and a bolt 50 penetrates through the upper longitudinal opening groove and the lower longitudinal opening groove to fix the upper support 47 and the lower support 46. By adjusting the relative position between the upper support 47 and the lower support 46, the adjustment of the longitudinal position of the welded pipe 1 can be realized.

Claims

1. A method for manufacturing a precision welded tube for an automotive shock absorber cylinder, characterized in that, This method involves longitudinally shearing pre-treated steel plates into strips and then coiling them. The two ends of the coiled steel plates are butt-welded to form a tube blank. Burrs are removed from the weld edges of the tube blank. The outer diameter of the tube blank is used as a reference for rough turning of its inner and outer sides. After rough turning, the inner wall of the tube blank is used as a reference for finish turning of its inner and outer sides. The inner wall of the finish-turned tube blank is then ground. Finally, the ground welded pipe undergoes post-processing. During grinding, a grinding wheel grinds the inner wall of the welded pipe, while a support wheel supports the area being ground on the outer wall. The welded pipe can rotate during grinding to complete the grinding of the entire circumference. The rotation direction of the grinding wheel and the support wheel is the same as that of the welded pipe. The grinding wheel and the support wheel rotate in opposite directions; the grinding wheel and the support wheel can simultaneously approach or move away from the processing wall surface of the welded pipe, and the grinding wheel and the support wheel can simultaneously move along the axial direction of the welded pipe and their movements are synchronized; the grinding wheel and the support wheel are synchronously controlled by a welded pipe preparation device, which includes a first transmission rod connected to the grinding wheel, a second transmission rod connected to the first transmission rod via a first ball joint, and a first spur gear coaxially connected to the second transmission rod; the welded pipe preparation device also includes a third transmission rod connected to the support wheel, a fourth transmission rod connected to the third transmission rod via a second ball joint, and a second spur gear coaxially connected to the fourth transmission rod. The first gear and the second spur gear simultaneously mesh with the third spur gear, which is driven to rotate by the first motor. The first and third transmission rods have identical structures. The first transmission rod includes a vertical outer rod, a vertical inner rod with one end slidably disposed within the vertical outer rod, and a spring connecting the vertical outer rod and the vertical inner rod. The vertical outer rod is fixedly connected to a grinding wheel or a support wheel. A sliding rod is provided on the outer side of the vertical inner rod, and a groove is formed on the outer side of the vertical outer rod to mate with the sliding rod. A movable block is rotatably fitted on the outer side of the vertical inner rod. A guide rod slides through the movable block and is fixedly connected to a support plate. The movable block is also threadedly connected to a screw. The two movable blocks... The threads rotate in opposite directions. The screw is connected to a first bevel gear, which meshes with a second bevel gear. The second bevel gear is coaxially connected to a rotating shaft, which is connected to the output end of a second motor. The second motor is fixedly connected to a support, and the support plate is fixed on the upper side of the support. A rotating sleeve is rotatably mounted on the vertical outer rod. The two ends of the rotating sleeve are axially limited by an upper limit plate and a lower limit plate, which are fixed to the vertical outer rod at intervals. A transverse outer rod is fixed to the outside of the rotating sleeve on the first transmission rod, and the outside of the rotating sleeve on the third transmission rod is fixed to one end of the transverse inner rod. The other end of the transverse inner rod is slidably mounted inside the transverse outer rod.

2. The method for manufacturing precision welded pipe for automobile shock absorber cylinders according to claim 1, characterized in that, A sliding plate is provided on the support, and the sliding plate is connected to the rotating support platform through a telescopic device. The two ends of the telescopic device are respectively connected to the sliding plate and the rotating support platform.

3. The method for manufacturing precision welded pipe for automobile shock absorber cylinders according to claim 2, characterized in that, The slide plate is slidably mounted on the support. A first lateral limiting plate and a second lateral limiting plate are provided on both sides of the slide plate. A limiting groove for limiting the slide plate is formed between the first lateral limiting plate and the second lateral limiting plate. The first lateral limiting plate and the second lateral limiting plate are connected to the limiting block through an L-shaped bracket. An arc-shaped groove is provided on one side of the limiting block. The arc-shaped groove is used to limit the radial direction of the welded pipe.

4. The method for manufacturing precision welded pipe for automobile shock absorber cylinders according to claim 3, characterized in that, The back side of the limiting block is connected to a rack via a support block. The support has a transverse opening slot for the support block to engage. The rack meshes with a gear, and the gear is controlled to rotate by a third motor, which is fixed to the support.

5. The method for manufacturing precision welded pipe for automobile shock absorber cylinders according to claim 4, characterized in that, The support includes a lower support and an upper support. The upper end of the lower support is provided with a lower connecting plate, and the lower end of the upper support is provided with an upper connecting plate. The upper connecting plate and the lower connecting plate are respectively provided with an upper longitudinal opening groove and a lower longitudinal opening groove. The upper support and the lower support are fixed by bolts passing through the upper longitudinal opening groove and the lower longitudinal opening groove simultaneously.

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