Circulating auxiliary flaw detection device for multiple pipelines

Abstract

The utility model relates to a circulating auxiliary flaw detection device for multiple pipelines, which relates to the technical field of pipeline flaw detection and comprises a platform, a right support and a left support which are respectively mounted at two ends of the top surface of the platform, and a connecting rod for connecting the right support and the left support, the right support comprises a right support plate arranged on the platform, a right driving wheel arranged on the right support plate and a right rotating wheel arranged on the right driving wheel, the left support comprises a left support plate arranged on the platform, a left driving wheel arranged on the left support plate and a left rotating wheel arranged on the left driving wheel, and the two ends of the connecting rod penetrate through the right rotating wheel and the left rotating wheel at the same time. The right rotating wheel and the left rotating wheel are provided with pipe holes used for installing pipelines, and the pipelines can be rotated by rotating the left rotating wheel and the right rotating wheel. The utility model is favorable for meeting the radiographic inspection requirement, omits the counterweight process to shorten the manufacturing period, reduces the cost and eliminates the potential safety hazard.

Description

Technical Field

[0001] This utility model relates to the field of pipeline flaw detection technology, and in particular to a multi-pipeline circulating auxiliary flaw detection device and method. Background Technology

[0002] With the improvement of parameters in ultra-supercritical and supercritical boilers, the material grade and wall thickness of the pipes in these boilers are also gradually increasing. Currently, before radiographic testing of the circumferential seams of 90-degree elbow pipes, a temporary counterweight needs to be installed at the other end of the pipe (the non-elbow end). The counterweight is connected and fixed to the pipe using C-clamps. Then, the elbow and counterweight are placed together on an electric roller frame, which drives the pipe to rotate, enabling radiographic testing at different locations along the pipe joint circumferential seam (the joint between the elbow and the straight section of the pipe body).

[0003] Using this method, if the applied counterweight is too heavy or too light, the pipe will not rotate smoothly on the roller frame or will slip. This necessitates readjusting the counterweight, affecting the radiographic testing of the pipe joint circumferential seams, resulting in a longer manufacturing cycle, higher manufacturing costs, and hindering workshop production. Furthermore, this method poses a significant safety risk to workers, as the C-clamps are prone to breakage, causing the pipe to tip over instantly. This posed a high safety hazard to personnel handling the hooks and those performing non-destructive testing. Utility Model Content

[0004] The purpose of this invention is to provide a multi-pipe circulating auxiliary flaw detection device and method, which meets flaw detection requirements, optimizes the manufacturing process, reduces costs, and eliminates safety hazards by automatically clamping, rotating, and releasing the pipes.

[0005] To achieve the above objectives, the present invention provides a multi-pipe circulating auxiliary flaw detection device, comprising a platform, a right support and a left support respectively installed at both ends of the top surface of the platform, and a connecting rod connecting the right support and the left support; the right support includes a right support plate on the platform, a right drive wheel on the right support plate, and a right rotating wheel on the right drive wheel; the left support includes a left support plate on the platform, a left drive wheel on the left support plate, and a left rotating wheel on the left drive wheel; the connecting rod passes through both the right rotating wheel and the left rotating wheel simultaneously; the right rotating wheel and the left rotating wheel are provided with pipe holes for installing pipes, and the pipes can be rotated by rotating the left rotating wheel and the right rotating wheel.

[0006] Preferably, the right support plate and the left support plate are provided with grooves that can accommodate the right rotating wheel and the left rotating wheel.

[0007] Preferably, there are two right support plates and two left support plates, which are spaced apart and each is equipped with a plurality of right drive wheels and left drive wheels.

[0008] Preferably, both the right drive wheel and the left drive wheel have convex teeth at their axial center, and both the right rotating wheel and the left rotating wheel have corresponding meshing convex teeth at their axial center; both ends of the right drive wheel and the left drive wheel are respectively provided with rings, and both ends of the right rotating wheel and the left rotating wheel are respectively provided with rings that have corresponding rolling contact.

[0009] Preferably, the right rotating wheel and the left rotating wheel are respectively provided with multiple pipe holes, and each pipe hole is provided with a clamping claw for clamping the pipe.

[0010] Preferably, both the right and left rotating wheels have small holes at their center-upper and lower positions, and large holes at their center-left and right positions.

[0011] Preferably, four small clamping claws are distributed corresponding to the small tube hole, and four large clamping claws are distributed corresponding to the large tube hole.

[0012] Preferably, a remote control device is also provided for controlling the right drive wheel and the left drive wheel to rotate clockwise or counterclockwise at the same time, and for the chucks to clamp or release at the same time.

[0013] Preferably, the two ends of the connecting rod pass through the right rotating wheel and the left rotating wheel respectively and are detachably connected to the cross plate.

[0014] The technical solution of this utility model also provides a method for cyclic auxiliary flaw detection of multiple pipelines, including the following steps:

[0015] A single 90-degree elbow pipe is clamped and fixed in the corresponding pipe holes of the right and left rotating wheels, with the 90-degree elbow in the pipe facing upwards.

[0016] The first irradiation operation in the X-direction direction is completed by irradiating the annular seam with a ray source at the X-direction position.

[0017] The left and right drive wheels are controlled to rotate by a remote control device, causing the left and right wheels to rotate 90 degrees counterclockwise and then stop immediately, thus rotating the pipe 90 degrees.

[0018] The second irradiation operation in the Y direction is completed by irradiating the annular seam with a ray source at the Y position.

[0019] The left and right drive wheels are rotated again by the remote control device, and the left and right wheels are rotated 90 degrees counterclockwise and then stopped immediately, and the pipeline rotates 90 degrees accordingly.

[0020] At the Z-axis position, the annular seam is irradiated with X-rays by a X-ray source, completing the third X-ray irradiation operation in the Z-axis direction;

[0021] This allows for X-ray irradiation of the 90-degree elbow and the pipe body joint in three directions: X, Y, and Z, thus completing the X-ray inspection of the entire joint.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This invention provides a multi-pipe circulating auxiliary flaw detection device and method. The pipes are placed on the equipment, and a remote control device controls the simultaneous rotation and stopping of the left and right rollers. This device enables automatic clamping, rotation, and release of the pipes, meeting the requirements for radiographic flaw detection of pipe and elbow circumferential seams. Compared to existing technologies, this device eliminates the need for installing counterweights at the pipe tail, significantly shortening the product manufacturing cycle, reducing manufacturing costs, and avoiding potential safety hazards for personnel.

[0024] This utility model device boasts advantages such as simple design, low manufacturing cost, and ease of use. By installing pipes into the corresponding large and small holes of the rotating wheel according to different pipe specifications and dimensions, it can clamp and rotate pipes of various specifications. Therefore, this utility model device has high versatility and practicality, facilitating large-scale deployment in production workshops. Attached Figure Description

[0025] Figure 1 This is a front view of a multi-pipe circulating auxiliary flaw detection device according to the present invention;

[0026] Figure 2 This is a view from direction A of a multi-pipe circulating auxiliary flaw detection device according to the present invention;

[0027] Figure 3 This is a schematic diagram showing the three X-ray irradiation positions required for the 90-degree elbow pipe of this utility model;

[0028] Figure 4 This is a schematic diagram showing the position of the first X-ray irradiation in the X-axis using the automated flaw detection device for circumferential seams of pipes with 90-degree bends according to this utility model.

[0029] Figure 5 This is a schematic diagram showing the position of the second X-ray irradiation in the Y direction achieved by the automated flaw detection device for circumferential seams of pipes with 90-degree bends according to this utility model.

[0030] Figure 6 This is a schematic diagram showing the position of the third X-ray irradiation in the Z-direction using the automated flaw detection device for circumferential seams of pipes with 90-degree bends according to this utility model.

[0031] Figure 7 This utility model presents a front view showing the installation and fixing of four pipe products in this device;

[0032] Figure 8 View B shows the installation and fixing of four pipe products in this device.

[0033] Figure 9 The present invention is illustrated by a C-direction view showing the installation and fixation of four pipe products in this device.

[0034] Attached reference numerals: 0. Platform; 1. Right support; 11. Right support plate; 12. Right drive wheel; 13. Pin 1; 14. Right rotating wheel; 15. Small tube hole 1; 16. Small chuck 1; 17. Large tube hole 1; 18. Large chuck 1; 2. Left support; 21. Left support plate; 22. Left drive wheel; 23. Pin 2; 24. Left rotating wheel; 25. Small tube hole 2; 26. Small chuck 2; 27. Large tube hole 2; 28. Large chuck 2; 3. Connecting rod; 4. Cross plate. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0036] This utility model discloses a multi-pipe circulating auxiliary flaw detection device, including a platform 0, a right support 1, a left support 2, a connecting rod 3, and a cross plate 4.

[0037] This invention uses platform 0 as the basic component. Platform 0 is made of alloy steel, possessing sufficient strength and stability to bear the weight of the entire device and various forces generated during flaw detection. Right support 1 and left support 2 are respectively installed at both ends of the top surface of platform 0, connected by a connecting rod 3. Connecting rod 3 is also made of alloy steel. One end of the connecting rod passes through right support 1, where a cross plate 4 connects to it. The connecting rod 3 has a cross groove at this end, precisely engaging with the slot of the cross plate 4 for a secure connection. The other end of the connecting rod 3 passes through left support 2, also having a cross groove, engaging with the slot of the other cross plate 4. This connection method not only provides a tight connection but also offers the advantage of quick installation and removal, facilitating the assembly and disassembly of the device. Furthermore, right support 1 and left support 2 are also made of alloy steel.

[0038] The right support 1 includes a right support plate 11, a right drive wheel 12, a pin 13, a right rotating wheel 14, a small pipe hole 15, a small chuck 16, a large pipe hole 17, and a large chuck 18. The right support 1 is connected to the connecting rod 3 via the right drive wheel 12. There are two right support plates 11, both with polygonal cross-sections and a V-shaped groove in the middle. This structure ensures overall strength and provides suitable installation space for other components. Between the two right support plates 11, three right drive wheels 12 are installed on both sides and in the middle. Each right drive wheel 12 is connected to the right support plate 11 by a pin 13. The pin 13 passes through the right drive wheel 12 and the corresponding hole on the right support plate 11, allowing the right drive wheel 12 to be stably installed between the right support plates 11 and to rotate around the pin 13. Corresponding to the structure of the right support 1, the left support 2 includes a left support plate 21, a left drive wheel 22, a second pin 23, a left rotating wheel 24, a second small tube hole 25, a second small chuck 26, a second large tube hole 27, and a second large chuck 28. The left support 2 is connected to the connecting rod 3 via the left drive wheel 22. There are two left support plates 21, both with polygonal cross-sections and a V-shaped groove in the middle. Between the two left support plates 21, three left drive wheels 22 are installed on both sides and in the middle. The second pin 23 connects the left drive wheels 22 to the left support plates 21.

[0039] The right drive wheel 12 has a toothed center and rings at both ends. The right rotating wheel 14 is adapted to the right drive wheel 12, with rings at both ends and a toothed center. The right rotating wheel 14 meshes with the toothed center of the right drive wheel 12 to achieve transmission. The right rotating wheel 14 rolls with the rings of the right drive wheel 12 through the rings at both ends to ensure smooth transmission. The left drive wheel 22 corresponds to the right drive wheel 12, with a toothed center and rings at both ends. The left rotating wheel 24 is adapted to the right rotating wheel 14, with rings at both ends and a toothed center. The left rotating wheel 24 meshes with the cam of the left drive wheel 22 through the cam in the center. The left rotating wheel 24 rolls with the rings of the left drive wheel 22 through the rings at both ends.

[0040] The right-hand rotating wheel 14 has a small pipe hole 15 located above and below its center. Each small pipe hole 15 is surrounded by four small clamping claws 16, which can clamp or release the pipe, thus securely installing small-diameter pipes (pipe body diameter range: 200–500 mm) within the small pipe hole 15. Simultaneously, the right-hand rotating wheel 14 also has a large pipe hole 17 located to its left and right. Each large pipe hole 17 is surrounded by four large clamping claws 18, which are used to install large-diameter pipes (pipe body diameter range: 400–700 mm). By clamping or releasing the large clamping claws 18, the large-diameter pipe is securely clamped within the large pipe hole 17. The left rotating wheel 24 corresponds to the right rotating wheel 14 in structure. It has a small pipe hole 25 at the top and bottom of its center, and four small clamping claws 26 are evenly distributed around each small pipe hole 25 for clamping small-diameter pipes. The left rotating wheel 24 also has a large pipe hole 27 at the left and right of its center, and four large clamping claws 28 are evenly distributed around each large pipe hole 27 for clamping large-diameter pipes. Both the small clamping claws 26 and the large clamping claws 28 can clamp or release the pipe.

[0041] Platform 0 has a right support 1 and a left support 2. The right rotating wheel 14 in right support 1 and the left rotating wheel 24 in left support 2 are at the same horizontal height to ensure the pipeline remains stable during clamping and flaw detection. Furthermore, the upper and lower small pipe holes 15 and the left and right large pipe holes 17 in right rotating wheel 14 are respectively positioned at the same angle as the upper and lower small pipe holes 25 and the left and right large pipe holes 27 in left rotating wheel 24. This ensures precise alignment of the holes on both sides during pipeline clamping, facilitating pipeline installation and fixation. A connecting rod 3 passes through the center of right rotating wheel 14 and left rotating wheel 24. All components are welded together to ensure a strong and stable connection. The connecting rod 3 protrudes from the ends of right rotating wheel 14 and left rotating wheel 24. Both ends of the connecting rod 3 have cross grooves, and cross plates 4 are installed at both ends. The connecting rod 3 and the cross plates 4 are connected in a slotted fit, allowing for quick installation and removal.

[0042] This utility model can also be equipped with a remote control device, whose control functions are as follows:

[0043] This remote control device enables the three right drive wheels 12 in the right support 1 and the three left drive wheels 22 in the left support 2 to rotate simultaneously clockwise or counterclockwise. It also ensures that the three right drive wheels 12 and the three left drive wheels 22 rotate at the same speed, allowing the drive wheels on both sides to operate synchronously and providing stable power for the rotation of the wheels. Simultaneously, the right rotating wheel 14 in the right support 1 and the left rotating wheel 24 in the left support 2 rotate in the same direction and at the same speed, achieving synchronous rotation and stopping of the right rotating wheel 14 and the left rotating wheel 24. In other words, this remote control device enables the right rotating wheel 14 and the left rotating wheel 24 to rotate and stop simultaneously, with all rotation directions and speeds being identical.

[0044] This remote control device enables the four small clamping jaws 16 in the upper and lower small pipe holes 15 of the right rotating wheel 14 and the four small clamping jaws 26 in the upper and lower small pipe holes 25 of the left rotating wheel 24 to simultaneously clamp or release, facilitating the quick clamping and disassembly of small-diameter pipes. Similarly, this remote control device enables the four large clamping jaws 18 in the left and right large pipe holes 17 of the right rotating wheel 14 and the four large clamping jaws 28 in the left and right large pipe holes 27 of the left rotating wheel 24 to simultaneously clamp or release, meeting the clamping and disassembly requirements of large-diameter pipes.

[0045] The implementation principle of this utility model embodiment is as follows:

[0046] In the application scenarios of the device, for the radiographic testing of the circumferential seam where a 90-degree elbow meets the pipe body, it is necessary to irradiate the seam with X-rays in three directions: X, Y, and Z. In this embodiment, a single 90-degree elbow pipe can be clamped and fixed in the small pipe hole 25 located at the upper center of the left rotating wheel 24 and the small pipe hole 15 located at the upper center of the right rotating wheel 14, with the 90-degree elbow in the pipe facing upwards. At this time, the circumferential seam is irradiated with X-rays in the X-direction, completing the first X-ray irradiation operation in the X-direction.

[0047] The remote control device in this apparatus controls the rotation of the left drive wheel 22 and the right drive wheel 12, thereby causing the left rotating wheel 24 and the right rotating wheel 14 to rotate 90 degrees counterclockwise and then immediately stop. By controlling the rotation and stopping of the left drive wheel 22 and the right drive wheel 12, the left rotating wheel 24 and the right rotating wheel 14 are locked after rotating 90 degrees counterclockwise, achieving the purpose of rotating the pipeline 90 degrees. At this time, the circumferential seam is irradiated by a radiation source in the Y direction, completing the second radiation irradiation operation in the Y direction.

[0048] The remote control device in this apparatus controls the rotation of the left drive wheel 22 and the right drive wheel 12, causing the left and right wheels 24 and 14 to rotate 90 degrees counterclockwise and then immediately stop. Similarly, by controlling the rotation and stopping of the left and right drive wheels 22 and 12, the left and right wheels 24 and 14 are rotated another 90 degrees and locked, and the pipe also rotates 90 degrees accordingly. At this time, the annular seam is irradiated by a radiation source at the Z-axis position, completing the third radiation irradiation operation in the Z-axis direction.

[0049] This utility model device drives the product pipeline to rotate counterclockwise by 90 degrees twice through the left rotating wheel 24 and the right rotating wheel 14, which can realize the X-ray irradiation of the circumferential seam between the 90-degree elbow and the pipeline body in three positions: X, Y and Z. It can efficiently complete the X-ray flaw detection operation of the entire circumferential seam. Its structural design is reasonable and the components work together to provide stable and convenient auxiliary support for pipeline flaw detection.

[0050] Specifically, the steps for using this utility model are as follows:

[0051] 1. Clean the components in this utility model device. Using the remote control device, control the rotation of the left drive wheel 22 and the right drive wheel 12, so that the left and right wheels 24 rotate counterclockwise by a certain angle and then immediately stop. That is, by controlling the rotation and stopping functions of the left drive wheel 22 and the right drive wheel 12, the left and right wheels 24 rotate counterclockwise by a certain angle and then immediately stop, remaining in a locked state at that position. Test the stability and reliability of the mechanism.

[0052] 2. Based on the outer diameter of the pipe, select two smaller 90-degree elbow pipes. Insert one pipe through the small pipe hole 15 in the right support 1 and through the small pipe hole 15 in the left support 2. Use the remote control device in this device to control the small clamp to clamp the 90-degree elbow in the pipe with the 90-degree elbow facing upwards. Insert the other pipe through the small pipe hole 25 in the left support 2 and through the small pipe hole 25 in the right support 1. Use the remote control device in this device to control the small clamp to clamp the 90-degree elbow in the pipe with the 90-degree elbow facing downwards. The purpose is to use the two 90-degree elbows, one facing upwards and the other downwards, to symmetrically offset the rotational eccentricity of the pipe.

[0053] 3. Based on the outer diameter specifications of the pipes, select two larger 90-degree elbow pipes. Insert one pipe through the large pipe hole 17 in the right support 1 and through the large pipe hole 27 in the left support 2. Use the remote control device in this device to control the large clamp to clamp the 90-degree elbow in the pipe with the 90-degree elbow facing inward. Insert the other pipe through the large pipe hole 27 in the left support 2 and through the large pipe hole 27 in the right support 1. Use the remote control device in this device to control the large clamp to clamp the 90-degree elbow in the pipe with the 90-degree elbow facing outward. The purpose is to use the two 90-degree elbows, one facing inward and the other outward, to symmetrically offset the rotational eccentricity of the pipes.

[0054] 4. Using the remote control device in this apparatus, and following the implementation principle, the left and right rotating wheels 24 and 14 drive the product pipeline to rotate 90 degrees counterclockwise each time. This allows for the radiographic testing of the circumferential seams between the four pipe elbows and the pipe body in the apparatus. The circumferential seams are then irradiated with X-rays in the X, Y, and Z directions, completing the radiographic testing operation of the circumferential seams between the four pipe elbows and the pipe body. Cross plates 4 are installed at both ends of the connecting rod 3 through the cross grooves at both ends of the connecting rod 3. The cross plates 4 are made of lead steel plates and are arranged in a cross shape. The plates are welded together. The cross plates 4 have a radiographic isolation function, ensuring that there is no mutual interference or interference when the circumferential seams between the four pipe elbows and the pipe body are irradiated with X-rays.

[0055] 5. After the radiographic testing of the circumferential seams of all four pipes in this device is completed, use the remote control device in this device to lock the position and release the large / small clamps at the lowest position of the device. Use a crane to lift one of the product pipes away. Next, use the remote control device to rotate the left and right rotating wheels 24 and 14 180 degrees and immediately stop them. In this locked position, control the release of the large / small clamps at the lowest position of the device. Use a crane to lift the other product pipe of the same specification away. Then... Using the remote control device in this device, the left rotating wheel 24 and the right rotating wheel 14 are rotated 90 degrees and then immediately stopped. In this position, they are in a locked state. The large / small clamping jaws at the lowest position of the current device are then released, and one of the product pipes is lifted off using a crane. Finally, using the remote control device in this device, the left rotating wheel 24 and the right rotating wheel 14 are rotated 180 degrees and then immediately stopped. In this position, they are in a locked state. The large / small clamping jaws at the lowest position of the current device are then released, and another product pipe of the same specification is lifted off using a crane.

[0056] 6. After completing all the above operation steps, the four pipes can be detached from the device of this utility model;

[0057] 7. Repeat the above steps to perform circumferential radiographic testing on the other 4 pipes (2 sets of pipes).

[0058] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A multi-pipe circulating auxiliary flaw detection device, characterized in that, The system includes a platform (0), a right support (1) and a left support (2) respectively installed at both ends of the top surface of the platform (0), and a connecting rod (3) connecting the right support (1) and the left support (2); the right support (1) includes a right support plate (11) on the platform (0), a right drive wheel (12) on the right support plate (11), and a right rotating wheel (14) on the right drive wheel (12); the left support (2) includes a right support plate (11) on the platform (0), a right drive wheel (12) on the right support plate (11), and a right rotating wheel (14) on the right drive wheel (12); The platform (0) has a left support plate (21), a left drive wheel (22) on the left support plate (21), and a left rotating wheel (24) on the left drive wheel (22). The connecting rod (3) has the right rotating wheel (14) and the left rotating wheel (24) passing through both ends. The right rotating wheel (14) and the left rotating wheel (24) are provided with pipe holes for installing pipes. The pipes can be rotated by rotating the left rotating wheel (24) and the right rotating wheel (14).

2. The multi-pipe circulating auxiliary flaw detection device according to claim 1, characterized in that, The right support plate (11) and the left support plate (21) are provided with grooves that can accommodate the right rotating wheel (14) and the left rotating wheel (24).

3. The multi-pipe circulating auxiliary flaw detection device according to claim 2, characterized in that, The right support plate (11) and the left support plate (21) are both provided as two and are spaced apart, and are respectively equipped with multiple right drive wheels (12) and left drive wheels (22).

4. The multi-pipe circulating auxiliary flaw detection device according to claim 3, characterized in that, The right drive wheel (12) and the left drive wheel (22) are provided with convex teeth in the middle of their axial direction, and the right rotating wheel (14) and the left rotating wheel (24) are provided with corresponding meshing convex teeth in the middle of their axial direction; the right drive wheel (12) and the left drive wheel (22) are provided with rings at both ends, and the right rotating wheel (14) and the left rotating wheel (24) are provided with rings at both ends that have corresponding rolling contact.

5. The multi-pipe circulating auxiliary flaw detection device according to claim 4, characterized in that, The right rotating wheel (14) and the left rotating wheel (24) are respectively provided with multiple pipe holes, and each pipe hole is provided with a clamping claw for clamping the pipe.

6. The multi-pipe circulating auxiliary flaw detection device according to claim 5, characterized in that, Both the right rotating wheel (14) and the left rotating wheel (24) have small tube holes at the top and bottom of the center, and large tube holes at the left and right of the center.

7. The multi-pipe circulating auxiliary flaw detection device according to claim 6, characterized in that, The small tube hole has four small clamping claws, and the large tube hole has four large clamping claws.

8. A multi-pipe circulating auxiliary flaw detection device according to any one of claims 5-7, characterized in that, It is also equipped with a remote control device for controlling the right drive wheel (12) and the left drive wheel (22) to rotate clockwise or counterclockwise at the same time, and for the chucks to clamp or release at the same time.

9. A multi-pipe circulating auxiliary flaw detection device according to claim 8, characterized in that, The two ends of the connecting rod (3) pass through the right rotating wheel (14) and the left rotating wheel (24) respectively and are detachably connected to the cross plate (4).

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