Spiral welded pipe cutting and grinding all-in-one machine

Abstract

The invention discloses a spiral welded pipe cutting and grinding all-in-one machine which comprises a base, a fixing cylinder is connected to the base, a linear displacement mechanism is arranged in the fixing cylinder, a clamping mechanism is connected to a straight line through the displacement mechanism, a spiral welded pipe is clamped through the clamping mechanism, and the clamping mechanism is driven by the linear displacement mechanism to do linear motion. One end of the fixed cylinder is rotationally connected with a rotating cylinder, a first driving mechanism for driving the rotating cylinder to rotate is arranged on the fixed cylinder, and a cutting mechanism and a polishing mechanism are mounted on the rotating cylinder; the cutting mechanism comprises a plurality of groups of cutting units arranged along the circumference of the rotating cylinder, and the polishing mechanism comprises a plurality of groups of polishing units arranged along the circumference of the rotating cylinder. And through the multiple sets of cutting units and the multiple sets of polishing units, in cooperation with rotation of the rotating cylinder, efficient cutting can be carried out firstly, and efficient polishing can be carried out at the first time after cutting is completed.

Description

Technical Field

[0001] The present invention relates to the technical field of cutting and grinding, and particularly to an integrated cutting and grinding machine for spiral welded pipes. Background Art

[0002] Spiral welded pipes are made by rolling low-carbon structural steel or low-alloy structural steel strips into pipe blanks at a certain spiral angle and then welding the pipe seams. When producing such spiral welded pipes, it is generally necessary to cut the spiral welded pipes and then grind the cutting points.

[0003] However, the following problems exist in the current cutting and grinding of spiral welded pipes: (1) Cutting and grinding are carried out separately. That is, after cutting is completed, the spiral welded pipe needs to be sent to the grinding device, and then the spiral welded pipe is ground by the grinding device, resulting in low cutting and grinding efficiency; (2) During cutting, a cutting knife is brought into contact with the spiral welded pipe, the cutting knife is driven to rotate, and at the same time the spiral welded pipe is driven to rotate, and the spiral welded pipe is cut by one cutting knife, resulting in low cutting efficiency; similarly, during grinding, only one grinding wheel can be used to grind the spiral welded pipe, resulting in low grinding efficiency. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides an integrated cutting and grinding machine for spiral welded pipes to solve the problems mentioned in the above background art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A spiral welded pipe cutting and grinding integrated machine, comprising a base, a fixed cylinder is connected to the base, a linear displacement mechanism is arranged in the fixed cylinder, and a clamping mechanism is connected through the displacement mechanism. The spiral welded pipe is clamped by the clamping mechanism, and the clamping mechanism is driven to move linearly by the linear displacement mechanism. One end of the fixed cylinder is rotatably connected to a rotating cylinder, and a first driving mechanism for driving the rotating cylinder to rotate is arranged on the fixed cylinder. A cutting mechanism and a grinding mechanism are installed on the rotating cylinder; the cutting mechanism includes a plurality of cutting units arranged along the circumference of the rotating cylinder. Each cutting unit includes a first bracket installed on the outer wall of the rotating cylinder, a first cylinder installed on the first bracket, a first box body connected to the telescopic end of the first cylinder, two first connecting plates connected to the bottom surface of the first box body, a first rotating shaft rotatably connected to the two first connecting plates, a cutting knife fixedly connected to the first rotating shaft, and a second driving mechanism installed on the first box body and used for driving the first rotating shaft to rotate. A plurality of first through holes located on the same circumference are formed in the rotating cylinder, and the first box bodies correspond to the first through holes one by one, and the first box bodies are movably arranged in the corresponding first through holes; the grinding mechanism includes a plurality of grinding units arranged along the circumference of the rotating cylinder. Each grinding unit includes a second bracket installed on the outer wall of the rotating cylinder, a second cylinder installed on the second bracket, a second box body connected to the telescopic end of the second cylinder, two second connecting plates connected to the bottom surface of the second box body, a second rotating shaft rotatably connected to the two second connecting plates, a grinding wheel fixedly connected to the second rotating shaft, and a third driving mechanism installed on the second box body and used for driving the second rotating shaft to rotate. A plurality of second through holes located on the same circumference are formed in the rotating cylinder, and the second box bodies correspond to the second through holes one by one, and the second box bodies are movably arranged in the corresponding second through holes.

[0007] Preferably, two symmetrical grooves are provided on the inner wall of the fixed cylinder. The linear displacement mechanism includes a lead screw rotatably connected to one of the grooves, a guide rod connected to the other groove, and a first motor installed at one end of the fixed cylinder. The first motor is in transmission connection with the lead screw. The clamping mechanism includes a sleeve. One end of the sleeve is connected with a transmission block, the transmission block is in threaded connection with the lead screw, the other end is connected with a slider, the slider is slidably connected with the guide rod, and a plurality of third cylinders on the same circumference are installed in the sleeve. The telescopic end of the third cylinder is connected with a clamping plate, and the side of the clamping plate facing the center of the sleeve is arc-shaped.

[0008] In the above technical solution, by controlling the extension of the third cylinder, the clamping plate is driven to move towards the center of the fixed cylinder, so that the clamping plate presses tightly on the spiral welded pipe, thereby enabling the spiral welded pipe to be kept stable. When it is necessary to move the spiral welded pipe, control the first motor to work, which can drive the lead screw to rotate, and then drive the sleeve to move along the guide rod to control the movement of the clamping mechanism and the spiral welded pipe thereon.

[0009] Preferably, the first driving mechanism includes a second motor installed on the fixed sleeve, a first transmission shaft connected to the second motor through a coupling, a first gear connected to the first transmission shaft, and a second gear connected to the rotating cylinder. The first gear meshes with the second gear.

[0010] In the above technical solution, when the second motor is started, it drives the first transmission shaft to rotate. Through the cooperation of the first gear and the second gear, the rotating cylinder can be driven to rotate.

[0011] Preferably, the second driving mechanism includes a third motor installed in the first box body, a second transmission shaft connected to the third motor through a coupling, a third gear connected to the second transmission shaft, and a fourth gear connected to the first rotating shaft. The third gear meshes with the fourth gear.

[0012] In the above technical solution, when the third motor is started, it drives the second transmission shaft to rotate. Through the cooperation of the third gear and the fourth gear, the first rotating shaft is driven to rotate, thereby driving the cutting tool to rotate.

[0013] Preferably, the third driving mechanism includes a fourth motor installed in the second box body, a third transmission shaft connected to the fourth motor through a coupling, a fifth gear connected to the third transmission shaft, and a sixth gear connected to the second rotating shaft. The fifth gear meshes with the sixth gear.

[0014] In the above technical solution, when the fourth motor is started, it drives the third transmission shaft to rotate. Through the cooperation of the fifth gear and the sixth gear, the second rotating shaft is driven to rotate, thereby driving the grinding wheel to rotate.

[0015] Preferably, a roller conveyor is provided on one side of the base, and a pressing mechanism is provided at one end of the roller conveyor close to the rotating cylinder; the pressing mechanism includes a U-shaped frame connected to the roller conveyor, a fourth cylinder installed on the top of the U-shaped frame, and a pressing plate connected to the telescopic end of the fourth cylinder. The bottom surface of the pressing plate is arc-shaped.

[0016] In the above technical solution, the spiral welded pipe can be conveyed towards the fixed cylinder through the roller conveyor to achieve automatic feeding. By extending the fourth cylinder, the pressing plate can be driven to descend to tightly press the spiral welded pipe on the roller conveyor, further keeping the spiral welded pipe stable.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) During cutting, one end of the spiral welded pipe is inserted into the rotating cylinder, and then the first cylinder is controlled to extend, driving the box body to move towards the spiral welded pipe in the first through hole until the cutting tool abuts against the spiral welded pipe. Then, the rotating cylinder is controlled to rotate through the first driving mechanism, and at the same time, the second driving mechanism controls the rotation of the first rotating shaft, and the first rotating shaft drives the cutting tool to rotate. When multiple cutting tools rotate simultaneously and are combined with the rotation of the rotating cylinder, the spiral welded pipe can be quickly cut, greatly improving the cutting efficiency.

[0019] (2) After cutting, through the cooperation of the clamping mechanism and the linear displacement mechanism, the spiral welded pipe is driven to move forward until the cutting position reaches the grinding wheel. Then, the second cylinder is controlled to extend, making the grinding wheel contact the spiral welded pipe. Then, the second rotating shaft is controlled to rotate through the third driving mechanism, driving the grinding wheel to rotate. When multiple grinding wheels rotate simultaneously and are combined with the rotation of the rotating cylinder, the spiral welded pipe can be quickly ground, greatly improving the grinding efficiency.

[0020] (3) When cutting is completed, there is no need to remove the spiral welded pipe, and it can be directly ground in the fixed cylinder, shortening the processing time of the spiral welded pipe and improving the cutting and grinding efficiency. Brief Description of the Drawings

[0021] Figure 1 is a schematic diagram of the present invention;

[0022] Figure 2 is a schematic diagram of the present invention when processing the spiral welded pipe;

[0023] Figure 3 is Figure 2 a partial enlarged view of;

[0024] Figure 4 is a cross-sectional view of the cutting mechanism and the rotating cylinder;

[0025] Figure 5 is a cross-sectional view of the fixed cylinder and the clamping mechanism;

[0026] Figure 6 is a cross-sectional view of the linear displacement mechanism and the clamping mechanism;

[0027] In the figure: 1 - base, 2 - fixed cylinder, 3 - rotating cylinder, 4 - first bracket, 5 - first cylinder, 6 - first box body, 7 - first connecting plate, 8 - first rotating shaft, 9 - cutting tool, 10 - first through hole, 11 - second bracket, 12 - second cylinder, 13 - second box body, 14 - second connecting plate, 15 - second rotating shaft, 16 - grinding wheel, 17 - second through hole, 18 - groove, 19 - lead screw, 20 - guide rod, 21 - first motor, 22 - sleeve, 23 - transmission block, 24 - slider, 25 - third cylinder, 26 - clamping plate, 27 - second motor, 28 - first gear, 29 - second gear, 30 - third motor, 31 - third gear, 32 - fourth gear, 33 - fourth motor, 34 - fifth gear, 35 - sixth gear, 36 - roller conveyor, 37 - U-shaped frame, 38 - fourth cylinder, 39 - pressing plate, 40 - spiral welded pipe. Detailed implementation mode

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Embodiment 1

[0030] Please refer to Figures 1-6, a spiral welded pipe cutting and grinding integrated machine, comprising a base 1, a fixed cylinder 2 is connected to the base 1, a linear displacement mechanism is arranged in the fixed cylinder 2, and a clamping mechanism is connected through the linear displacement mechanism. The spiral welded pipe is clamped by the clamping mechanism, and the clamping mechanism is driven to move linearly by the linear displacement mechanism. Specifically, two symmetrical grooves 18 are arranged on the inner wall of the fixed cylinder 2. The linear displacement mechanism comprises a lead screw 19 rotatably connected in one of the grooves, a guide rod 20 connected in the other groove, and a first motor 21 installed at one end of the fixed cylinder 2. The first motor 21 is in transmission connection with the lead screw 19. The clamping mechanism comprises a sleeve 22, a transmission block 23 is connected to one end of the sleeve 22, the transmission block 23 is in threaded connection with the lead screw 19, a slider 24 is connected to the other end, the slider 24 is slidably connected with the guide rod 20, and a plurality of third cylinders 25 in the same circumference are installed in the sleeve 22. The telescopic end of the third cylinder 25 is connected with a clamping plate 26, and the side of the clamping plate 26 facing the center of the sleeve 22 is arc-shaped. One end of the spiral welded pipe is inserted into the fixed cylinder 2. By controlling the extension of the third cylinder 25, the clamping plate 26 is driven to move towards the center of the fixed cylinder 2, so that the clamping plate 26 presses tightly on the spiral welded pipe, thereby enabling the spiral welded pipe to be kept stable. When it is necessary to move the spiral welded pipe, the first motor 21 is controlled to work, driving the lead screw 19 to rotate, thereby driving the sleeve 22 to move along the guide rod 20 to control the movement of the clamping mechanism and the spiral welded pipe thereon.

[0031] One end of the fixed cylinder 2 is rotatably connected with a rotating cylinder 3 through a rotating bearing, and a first driving mechanism for driving the rotating cylinder 3 to rotate is arranged on the fixed cylinder 2. Specifically, the first driving mechanism comprises a second motor 27 installed on the fixed sleeve, a first transmission shaft connected to the second motor through a coupling, a first gear 28 connected to the first transmission shaft, and a second gear 29 connected to the rotating cylinder. The first gear 28 is meshed with the second gear 29. When the second motor 27 is started, the first transmission shaft is driven to rotate, and through the cooperation of the first gear 28 and the second gear 29, the rotating cylinder 3 can be driven to rotate.

[0032] A cutting mechanism and a grinding mechanism are installed on the rotating cylinder 3. When the rotating cylinder 3 rotates, the cutting mechanism and the grinding mechanism will be driven to rotate together.

[0033] The cutting mechanism includes multiple groups of cutting units arranged along the circumference of the rotating cylinder. Each cutting unit includes a first bracket 4 installed on the outer wall of the rotating cylinder 3, a first cylinder 5 installed on the first bracket, a first box body 6 connected to the telescopic end of the first cylinder, two first connecting plates 7 connected to the bottom surface of the first box body, a first rotating shaft 8 rotatably connected to the two first connecting plates, a cutting knife 9 fixedly connected to the first rotating shaft, and a second driving mechanism installed on the first box body and used to drive the first rotating shaft 8 to rotate. The rotating cylinder 3 is provided with a plurality of first through holes 10 located on the same circumference. The first box body 6 corresponds to the first through holes 10 one by one, and the first box body 6 is movably arranged in the corresponding first through holes 10. Among them, the second driving mechanism includes a third motor 30 installed in the first box body, a second transmission shaft connected to the third motor through a coupling, a third gear 31 connected to the second transmission shaft, a fourth gear 32 connected to the first rotating shaft. The bottom of the first box body is provided with a first opening. The lower part of the third gear extends to the outside of the first opening, and the third gear 31 and the fourth gear 32 are meshed. Insert one end of the spiral welded pipe into the rotating cylinder 3. Through the extension of the first cylinder 5, the cutting knife 9 is driven to contact the spiral welded pipe. Then start the third motor 30. Through the cooperation of the third gear 31 and the fourth gear 32, the first rotating shaft 8 is driven to rotate, thereby driving the cutting knife 9 to rotate. By this method, all cutting units can be controlled to work simultaneously. Then, in combination with the rotation of the rotating cylinder 3, the spiral welded pipe can be quickly cut.

[0034] The grinding mechanism includes multiple groups of grinding units arranged along the circumference of the rotating cylinder. Each grinding unit includes a second bracket 11 installed on the outer wall of the rotating cylinder 3, a second cylinder 12 installed on the second bracket, a second box body 13 connected to the telescopic end of the second cylinder, two second connecting plates 14 connected to the bottom surface of the second box body, a second rotating shaft 15 rotatably connected to the two second connecting plates, a grinding wheel 16 fixedly connected to the second rotating shaft, and a third driving mechanism installed on the second box body and used to drive the second rotating shaft 15 to rotate. The rotating cylinder 3 is provided with a plurality of second through holes 17 located on the same circumference. The second box body 13 corresponds to the second through holes 17 one by one, and the second box body 13 is movably arranged in the corresponding second through holes 17. Among them, the third driving mechanism includes a fourth motor 33 installed in the second box body, a third transmission shaft connected to the fourth motor through a coupling, a fifth gear 34 connected to the third transmission shaft, a sixth gear 35 connected to the second rotating shaft. The bottom of the second box body is provided with a second opening. The lower part of the fifth gear extends to the outside of the first opening, and the fifth gear 34 and the sixth gear 35 are meshed.

[0035] After cutting is completed, move the spiral welded pipe forward so that the cutting part reaches the grinding wheel. Then, the second cylinder 12 extends, driving the grinding wheel 16 into contact with the spiral welded pipe. Next, start the fourth motor 33. Through the cooperation of the fifth gear 34 and the sixth gear 35, drive the second rotating shaft 15 to rotate, thereby driving the grinding wheel 16 to rotate. By this method, all grinding units can be controlled to work simultaneously. Coupled with the rotation of the rotating cylinder 3, the spiral welded pipe can be quickly ground.

[0036] The working principle of this embodiment is as follows:

[0037] Insert the spiral welded pipe 40 into the rotating cylinder 3 and extend it into the fixed cylinder 2. Then, control the third cylinder 25 to extend, driving the clamping plate 26 to move towards the center of the fixed cylinder 2, pressing the clamping plate 26 tightly against the spiral welded pipe to keep the spiral welded pipe stable. Then, the first cylinder 5 extends, driving the cutting knife 9 into contact with the spiral welded pipe. Next, start the third motor 30. Through the cooperation of the third gear 31 and the fourth gear 32, drive the first rotating shaft 8 to rotate, thereby driving the cutting knife 9 to rotate. By this method, all cutting units can be controlled to work simultaneously. Then, start the second motor 27 to drive the rotating cylinder 3 to rotate, and the spiral welded pipe can be quickly cut. When the spiral welded pipe cutting is completed, control the first cylinder to contract to make the cutting knife leave the spiral welded pipe. Then, control the first motor 21 to work, driving the lead screw 19 to rotate, thereby driving the sleeve 22 to move along the guide rod 20, moving the spiral welded pipe forward until the cutting point reaches the grinding wheel. Then, the second cylinder 12 extends, driving the grinding wheel 16 into contact with the spiral welded pipe. Next, start the fourth motor 33. Through the cooperation of the fifth gear 34 and the sixth gear 35, drive the second rotating shaft 15 to rotate, thereby driving the grinding wheel 16 to rotate. By this method, all grinding units can be controlled to work simultaneously. Coupled with the rotation of the rotating cylinder 3, the spiral welded pipe can be quickly ground.

[0038] Embodiment 2

[0039] The difference between this embodiment and Embodiment 1 is that a roller conveyor 36 is provided on one side of the base 1, and a pressing mechanism is provided at one end of the roller conveyor 36 close to the rotating cylinder 3. The pressing mechanism includes a U-shaped frame 37 connected to the roller conveyor, a fourth cylinder 38 installed on the top of the U-shaped frame, and a pressing plate 39 connected to the telescopic end of the fourth cylinder. The bottom surface of the pressing plate 39 is arc-shaped.

[0040] The spiral welded pipe can be conveyed towards the fixed cylinder 2 through the roller conveyor 36 to achieve automatic feeding. By extending the fourth cylinder 38, the pressing plate 39 can be driven to descend to tightly press the spiral welded pipe on the roller conveyor 36, further keeping the spiral welded pipe stable.

[0041] In addition, a hydraulic lifting device may be provided on the bottom surface of the base to adjust the heights of the fixed cylinder and the rotating cylinder so that the rotating cylinder can be aligned with the spiral welded pipe on the roller conveyor.

[0042] It should be noted that the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

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

Claims

1. A spiral welded pipe cutting and grinding machine, characterized in that: The invention comprises a base (1), a fixed cylinder (2) is connected to the base (1), a linear displacement mechanism is arranged in the fixed cylinder (2), and a clamping mechanism is connected to the linear displacement mechanism, the spiral welded pipe is clamped by the clamping mechanism, and the clamping mechanism is driven to perform linear motion by the linear displacement mechanism, one end of the fixed cylinder (2) is rotatably connected to a rotating cylinder (3), a first driving mechanism for driving the rotating cylinder (3) to rotate is arranged on the fixed cylinder (2), and a cutting mechanism and a grinding mechanism are installed on the rotating cylinder (3); The cutting mechanism comprises a plurality of cutting units arranged along the circumference of the rotating cylinder, the cutting units comprising a first bracket (4) mounted on the outer wall of the rotating cylinder (3), a first cylinder (5) mounted on the first bracket, a first box body (6) connected to the telescopic end of the first cylinder, two first connecting plates (7) connected to the bottom surface of the first box body, a first rotating shaft (8) rotatably connected to the two first connecting plates, a cutting knife (9) fixedly connected to the first rotating shaft, and a second driving mechanism mounted on the first box body and used for driving the first rotating shaft (8) to rotate. The rotating cylinder (3) is provided with a plurality of first through holes (10) located on the same circumference, the first box bodies (6) correspond to the first through holes (10) one by one, and the first box bodies (6) are movably arranged in the corresponding first through holes (10); The grinding mechanism comprises a plurality of grinding units arranged along the circumference of the rotating cylinder, the grinding units comprising a second bracket (11) mounted on the outer wall of the rotating cylinder (3), a second cylinder (12) mounted on the second bracket, a second box body (13) connected to the telescopic end of the second cylinder, two second connecting plates (14) connected to the bottom surface of the second box body, a second rotating shaft (15) rotatably connected to the two second connecting plates, a grinding wheel (16) fixedly connected to the second rotating shaft, and a third driving mechanism mounted on the second box body and used for driving the second rotating shaft (15) to rotate. The rotating cylinder (3) is provided with a plurality of second through holes (17) located on the same circumference, the second box bodies (13) correspond to the second through holes (17) one by one, and the second box bodies (13) are movably arranged in the corresponding second through holes (17).

2. The spiral welded pipe cutting and grinding machine according to claim 1, characterized in that: The inner wall of the fixed cylinder (2) is provided with two symmetrical grooves (18), and the linear displacement mechanism comprises a screw rod (19) rotatably connected to one of the grooves, a guide rod (20) connected to the other groove, and a first motor (21) installed at one end of the fixed cylinder, and the first motor (21) is transmission-connected to the screw rod (19).

3. The spiral welded pipe cutting and grinding machine according to claim 2, characterized in that: The clamping mechanism comprises a sleeve (22), one end of the sleeve (22) is connected to a transmission block (23), the transmission block (23) is threadedly connected to a screw rod (19), the other end is connected to a slider (24), the slider (24) is slidably connected to a guide rod (20), a plurality of third cylinders (25) on the same circumference are installed in the sleeve (22), a clamping plate (26) is connected to the telescopic end of the third cylinder (25), and the side of the clamping plate (26) facing the center of the sleeve (22) is arc-shaped.

4. The spiral welded pipe cutting and grinding machine according to claim 3, characterized in that: The first driving mechanism comprises a second motor (27) mounted on the fixed sleeve, a first transmission shaft connected to the second motor through a coupling, a first gear (28) connected to the first transmission shaft, and a second gear (29) connected to the rotating cylinder, wherein the first gear (28) is meshed with the second gear (29).

5. The spiral welded pipe cutting and grinding machine according to claim 4, characterized in that: The second driving mechanism comprises a third motor (30) installed in the first box body, a second transmission shaft connected to the third motor through a coupling, a third gear (31) connected to the second transmission shaft, and a fourth gear (32) connected to the first rotating shaft, wherein the third gear (31) and the fourth gear (32) are meshed.

6. The spiral welded pipe cutting and grinding machine according to claim 5, characterized in that: The third driving mechanism comprises a fourth motor (33) installed in the second box body, a third transmission shaft connected to the fourth motor through a coupling, a fifth gear (34) connected to the third transmission shaft, and a sixth gear (35) connected to the second rotating shaft, wherein the fifth gear (34) and the sixth gear (35) are meshed.

7. The spiral welded pipe cutting and grinding machine according to claim 6, characterized in that: A roller conveyor (36) is provided on one side of the base (1), and a clamping mechanism is provided on one end of the roller conveyor (36) close to the rotating cylinder (3).

8. The spiral welded pipe cutting and grinding machine according to claim 7, characterized in that: The clamping mechanism comprises a U-shaped frame (37) connected to the roller conveyor, a fourth cylinder (38) installed on the top of the U-shaped frame, and a pressing plate (39) connected to the telescopic end of the fourth cylinder, wherein the bottom surface of the pressing plate (39) is arc-shaped.

Images