A multi-working-condition detection type straightness test device

Abstract

The utility model relates to a coal mine fully mechanized working face equipment detection technical field, concretely relates to a kind of multi-working condition detection formula straightness test device, including rack, controllable load mechanism and the abutment of top plate adjusting mechanism, hydraulic support group and bottom plate adjusting mechanism in turn from top to bottom, bottom plate adjusting mechanism includes sub bottom plate and connecting mechanism, sub bottom plate is driven hydraulic support group around Y axis direction rotation by connecting mechanism, top plate adjusting mechanism includes top plate assembly and rotating rod, rotating rod drives top plate assembly around X axis direction rotation, and further drives hydraulic support group around X axis direction rotation, controllable load mechanism includes load block, load block and the push rod of hydraulic support group abut and slide on bottom plate adjusting mechanism, load block is equipped with the laser collimation sensor or the line type displacement sensor for detecting the relative pose of multiple load blocks. By combining working condition simulation, load control and laser collimation sensor or line type displacement sensor, a test device capable of accurately detecting push straightness is constructed.

Description

Technical Field

[0001] This utility model relates to the field of equipment testing technology for fully mechanized coal mining faces, specifically to a multi-condition testing device for straightness. Background Technology

[0002] Hydraulic supports, as the core equipment of longwall mining faces, are responsible for managing the roof, maintaining support space, and advancing the working face during production. They are the main support equipment and the equipment with the most complex positional relationships in the working face. Currently, in longwall mining methods, scraper conveyors are prone to "jumping up and down" during the moving process, resulting in poor engineering quality, poor coal flow transportation, and low production efficiency.

[0003] Numerous studies have investigated the straightening of scraper conveyors, revealing that adjusting the swing of the push rod directly affects the straightness of the conveyor. However, research on testing devices for straightening is currently lacking. Therefore, there is an urgent need for a testing device capable of simulating large inclination angles, pitching, and undulating floor conditions, and accurately detecting the straightness of the conveyor. Utility Model Content

[0004] The purpose of this invention is to provide a multi-condition detection straightness testing device to solve the existing technical problems in the background art.

[0005] The technical solution provided by this utility model is as follows: A multi-condition detection type straightness testing device is provided, including a frame, a controllable load mechanism, and a top plate adjustment mechanism, a hydraulic support assembly, and a bottom plate adjustment mechanism that are sequentially connected from top to bottom. The bottom plate adjustment mechanism is connected to the bottom of the frame and includes a sub-bottom plate and a connecting mechanism. The sub-bottom plate drives the hydraulic support assembly to rotate around the Y-axis direction through the connecting mechanism. The top plate adjustment mechanism abuts against the upper surface of the top beam of the frame. The top plate adjustment mechanism includes a top plate assembly and a rotating rod. The rotating rod drives the top plate assembly to rotate around the X-axis direction, thereby driving the hydraulic support assembly to rotate around the X-axis direction. The controllable load mechanism is installed on the bottom plate adjustment mechanism and includes a load block. The load block abuts against the push rod of the hydraulic support assembly and slides on the bottom plate adjustment mechanism. The load block is provided with a laser collimation sensor or a wire displacement sensor for detecting the relative posture of multiple load blocks.

[0006] Based on the above technical solution, the top plate adjustment mechanism further includes a first rotary cylinder, a third lifting cylinder, a lifting plate, a rocker arm, a pressure plate, a positioning pin, and a connecting piece. The cylinder body of the third lifting cylinder is fixedly connected to the frame. The piston rod of the third lifting cylinder drives the lifting plate to move along the Z-axis on the frame through the connecting piece. The frame is provided with positioning holes adapted to the positioning pin. Multiple positioning holes are provided along the Z-axis. The lifting plate is provided with pin holes adapted to the positioning pin. The positioning pin connects the lifting plate to the frame by sequentially inserting the pin holes and positioning holes. The lifting plate has a groove formed by the bottom surface being recessed upward along the Z-axis. The rocker arm is located in the groove. One end of the rocker arm is hinged to the piston rod of the first rotary cylinder, and the other end of the rocker arm is hinged to the side of the bottom surface of the lifting plate away from the first rotary cylinder. The bottom of the rocker arm is fixedly connected to the top of the top plate assembly. The rocker arm drives the top plate assembly to rotate around the Y-axis through the first rotary cylinder.

[0007] Based on the above technical solution, the top plate assembly includes an upper top plate, a lower top plate, and a pressure plate. The upper top plate is disposed above the lower top plate, and the top of the upper top plate is fixedly connected to the bottom of the rocker arm. The rotating rod extends along the X-axis and is rotatably disposed below the upper top plate. The upper part of the lower top plate is fixedly connected to the rotating rod. The top of the pressure plate is fixedly connected to the bottom of the lower top plate, and the bottom of the pressure plate abuts against the top of the hydraulic support assembly.

[0008] Preferably, the controllable load mechanism further includes a load base and a pushing cylinder. The load base is fixedly connected to the base plate adjustment mechanism. The pushing cylinder is arranged along the Y-axis direction. The cylinder body of the pushing cylinder is fixedly connected to the load base. The piston rod of the pushing cylinder is hinged to the load block.

[0009] Based on the above technical solution, the base plate adjustment mechanism further includes a base plate, a support rod, and a connector. The controllable load mechanism further includes a dumbbell pin. The base plate is fixedly connected to the mounting plate at the bottom of the frame via the support rod. The bottom of the sub-base plate is hinged to the top of the base plate via the connector. Multiple sub-base plates are arranged side by side along the X-axis. The hydraulic support group includes multiple hydraulic supports arranged side by side along the X-axis. Each hydraulic support is set on one sub-base plate and abuts against one load block. Multiple load blocks are connected in series via dumbbell pins.

[0010] Based on the above technical solution, the connecting mechanism includes a connecting plate, a first operating lever, a second operating lever, a first lifting cylinder, a second lifting cylinder, a first connecting rod, and a second connecting rod. Each sub-base plate has a first connecting rod and a second connecting rod connected to its side away from the controllable load mechanism. The first and second connecting rods are connected to opposite sides of the sub-base plate, and their bottoms are respectively connected to the second operating lever and the first operating lever. The first and second operating levers extend along the X-axis, with the second operating lever positioned between the first operating lever and the hydraulic support assembly. The connecting plate is fixedly connected to the end face of the base plate away from the controllable load mechanism and extends along the X-axis. Multiple first and second lifting cylinders are arranged on the connecting plate along the X-axis. Both the first and second lifting cylinders are positioned along the Z-axis. The first operating lever is hinged to the top of the piston rod of the first lifting cylinder, and the second operating lever is hinged to the top of the piston rod of the second lifting cylinder. The piston rods of the first and second lifting cylinders move in opposite directions but with equal displacements.

[0011] Preferably, the first rotary cylinder is equipped with a first laser rangefinder for measuring the extension distance of the cylinder piston rod, the hydraulic support base is equipped with two second laser rangefinders, and the push cylinder is equipped with a pressure sensor.

[0012] Preferably, both the first and second control levers are provided with sliding grooves, the sliding grooves are inverted T-shaped, and the bottoms of the first and second connecting rods are provided with inverted T-shaped sliders, which are engaged in the sliding grooves and slide within the sliding grooves.

[0013] The beneficial effects of the technical solution provided by this utility model are as follows: (1) By combining working condition simulation, load control and laser collimation sensor or wire displacement sensor, a test device capable of accurately detecting the straightness of the push was constructed.

[0014] (2) The top plate adjustment mechanism simulates a steep working face and various complex working conditions such as downward mining and upward mining. At the same time, a load is applied to the top of the hydraulic support group, and the angle of the working face is precisely controlled by a laser rangefinder.

[0015] (3) Multiple independent sub-base plates are used and the deflection state of each sub-base plate is adjusted to effectively simulate the uneven working surface in the coal mine, providing a more realistic test environment for the performance test of hydraulic supports under different terrain conditions.

[0016] (4) By equipping each hydraulic support with an independent and controllable load block and using a pressure sensor to precisely control the load size, the actual working conditions of the scraper conveyor during the pushing and shifting process are simulated more realistically, which significantly improves the accuracy and reliability of the test data. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a side view of the present invention; Figure 3 This is a schematic diagram showing the connection between the hydraulic support assembly and the base plate of this utility model; Figure 4 This is a cross-sectional view of the top plate adjustment mechanism of this utility model; Figure 5 This is a schematic diagram of the base plate adjustment mechanism of this utility model; Figure 6 This is a schematic diagram of the controllable load mechanism of this utility model; Figure 7 This is a schematic diagram of the structure of the first connecting rod of this utility model; Figure 8 This is a schematic diagram of the structure of the second connecting rod of this utility model. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments: In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0019] In the description of this utility model, it should be understood that the terms "left", "right", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0020] like Figures 1 to 8 As shown, a multi-condition testing device for straightness includes a frame 1, a controllable load mechanism, and a top plate adjustment mechanism, a hydraulic support group, and a bottom plate adjustment mechanism that are sequentially connected from top to bottom.

[0021] The top plate adjustment mechanism abuts against the upper surface of the top beam of the frame 1. The top plate adjustment mechanism includes a top plate assembly and a rotating rod 26. The rotating rod 26 drives the top plate assembly to rotate around the X-axis, thereby driving the hydraulic support assembly to rotate around the X-axis to simulate the working conditions of the hydraulic support 3 in both downward and upward mining operations. Specifically, the top plate assembly includes an upper top plate 24, a lower top plate 25, and a pressure plate 27. The upper top plate 24 is positioned above the lower top plate 25. The rotating rod 26 extends along the X-axis and is rotatably positioned below the upper top plate 24. The upper part of the lower top plate 25 is fixedly connected to the rotating rod 26. The top of the pressure plate 27 is fixedly connected to the bottom of the lower top plate 25, and the bottom of the pressure plate 27 abuts against the top of the hydraulic support assembly, thereby stably applying a top load to the hydraulic support assembly. The top plate adjustment mechanism also includes a first rotary cylinder 231, a third lifting cylinder 21, a lifting plate 23, a rocker arm 232, a pressure plate 27, a positioning pin 28, and a connecting piece 22. Four third lifting cylinders 21 are provided, and their cylinder bodies are respectively fixed on the four top beams of the frame 1. The piston rod of the third lifting cylinder 21 drives the lifting plate 23 to move along the Z-axis direction on the frame 1 through the connecting piece 22. The frame 1 is provided with positioning holes 11 that are compatible with the positioning pin 28. Multiple positioning holes 11 are provided along the Z-axis direction. The lifting plate 23 is provided with pin holes that are compatible with the positioning pin 28. When the piston rod of the third lifting cylinder 21 moves to a designated position, the positioning pin 28 connects the lifting plate 23 to the frame 1 by sequentially inserting into the pin hole and the positioning hole 11, thereby limiting the movement of the lifting plate 23. The lifting plate 23 has a groove formed by an upward indentation along the Z-axis on its bottom surface. The rocker arm 232 is located within the groove. One end of the rocker arm 232 is hinged to the piston rod of the first rotary cylinder 231, and the other end is hinged to the side of the bottom surface of the lifting plate 23 away from the first rotary cylinder 231. The bottom of the rocker arm 232 is fixedly connected to the top of the upper top plate 24. The rocker arm 232 drives the top plate assembly to rotate around the Y-axis through the first rotary cylinder 231, thereby driving the hydraulic support assembly to rotate around the Y-axis to simulate the working conditions of a large-angle working surface. The first rotary cylinder 231 is equipped with a first laser rangefinder for measuring the extension distance of the cylinder piston rod. The rotation angle of the rocker arm 232 is generated by converting the distance detected by the first laser rangefinder.

[0022] The controllable load mechanism is mounted on the base plate adjustment mechanism. It primarily applies load to the push rod and simultaneously simulates a scraper, serving as the object for straightening inspection. The controllable load mechanism includes a load base 65, a pushing cylinder 61, a load block 62, and a dumbbell pin 63. The load base 65 is fixedly connected to the base plate 41. The pushing cylinder 61 is arranged along the Y-axis, with its cylinder body fixedly connected to the load base 65. The piston rod of the pushing cylinder 61 is hinged to one end of the load block 62, and the other end of the load block 62 is hinged to the push rod of the hydraulic support 3. Multiple load blocks 62 are arranged along the X-axis, each corresponding to one pushing cylinder 61 and one push rod of the hydraulic support 3. Multiple load blocks 62 are connected in series via dumbbell pins 63. While the push rod moves the load block 62, the push cylinder 61 applies a load to the load block 62. By changing the flow rate of the push cylinder 61, the magnitude of the thrust applied to the load block 62 is changed, thereby changing the magnitude of the load.

[0023] In the initial state, fluid enters the rodless chamber of the push cylinder 61, pushing the piston rod to fully extend, thus completely pushing out the load block 62. The load block 62 connects to the push rod of the hydraulic support 3. Simultaneously, the hydraulic circuit flow rate is changed to determine the thrust applied to the load block 62 by the push cylinder 61, thereby obtaining the load that the push rod needs to push. After preparation, the pressure plate 27 is pressed down to fix the hydraulic support 3, and the hydraulic support 3 begins to push, moving the load block 62. When the pushing is complete, the piston rod of the push cylinder 61 is fully retracted. At this time, fluid enters the rod chamber, fixing the load block 62, and the hydraulic support 3 can perform the moving action.

[0024] The load block 62 is equipped with a laser collimation sensor or a wire displacement sensor for detecting the relative pose of multiple load blocks 62. The curve of the pose of the load block 62 is used to provide a reference for the movement of the hydraulic support, and can also be used to detect the straightness of multiple load blocks.

[0025] The base plate adjustment mechanism is connected to the bottom of the frame 1. The base plate adjustment mechanism includes a sub-base plate 42 and a connecting mechanism. The sub-base plate 42 drives the hydraulic support assembly to rotate around the Y-axis through the connecting mechanism. Specifically, the base plate adjustment mechanism also includes a base plate 41, a support rod 43, and a connector 47. The base plate 41 is fixedly connected to the mounting plate at the bottom of the frame 1 through the support rod 43. The bottom of the sub-base plate 42 is hinged to the top of the base plate 41 through the connector 47, ensuring its freedom of rotation around the Y-axis and providing support. Multiple sub-base plates 42 are arranged side by side along the X-axis. The hydraulic support assembly includes multiple hydraulic supports 3 arranged side by side along the X-axis. Each hydraulic support 3 is respectively mounted on one sub-base plate 42 and abuts against one load block 62. The connecting mechanism includes a connecting plate 57, a first operating lever 51, a second operating lever 53, a first lifting cylinder 52, a second lifting cylinder 54, a first connecting rod 55, and a second connecting rod 56. Each sub-base plate 42 has a first connecting rod 55 and a second connecting rod 56 connected to the side furthest from the controllable load mechanism. The first connecting rod 55 and the second connecting rod 56 are connected to opposite sides of the sub-base plate 42. The bottoms of the first connecting rod 55 and the second connecting rod 56 are respectively connected to the second operating lever 53 and the first operating lever 51. The first operating lever 51 and the second operating lever 53 extend along the X-axis direction, and the second operating lever 53 is located at the first... A control lever 51 is connected to a hydraulic support assembly; the connecting plate 57 is fixedly connected to the end face of the base plate 41 away from the controllable load mechanism and extends along the X-axis; there are multiple first lifting cylinders 52 and second lifting cylinders 54, arranged on the connecting plate 57 along the X-axis, and both the first lifting cylinders 52 and second lifting cylinders 54 are set along the Z-axis. The first control lever 51 is hinged to the top of the piston rod of the first lifting cylinder 52, and the second control lever 53 is hinged to the top of the piston rod of the second lifting cylinder 54. The piston rods of the first lifting cylinder 52 and the second lifting cylinder 54 move in opposite directions and have equal displacements. Since the first connecting rod 55 and the second connecting rod 56 will move when the base plate 42 deflects, the first control lever 51 and the second control lever 53 are both provided with sliding grooves. The sliding grooves are inverted T-shaped, and the bottoms of the first connecting rod 55 and the second connecting rod 56 are provided with inverted T-shaped sliders. The inverted T-shaped sliders are engaged in the sliding grooves and slide within the sliding grooves. This ensures that the connecting rod can move on the control lever, and also facilitates the machining of the control lever and the installation of the connecting rod.

[0026] When the first lifting cylinder 52 controls the first control lever 51 to rise or fall, it will cause all the second connecting rods 56 connected to the first control lever 51 to rise or fall. At the same time, the second control lever 53 will rise or fall in the opposite direction, causing all the first connecting rods 55 connected to the second control lever 53 to rise or fall, thereby causing the sub-base plate 42 to rotate around the Y-axis. The connection positions of each sub-base plate 42 and the control lever can be changed as needed. By adjusting the deflection state of each sub-base plate 42, the uneven working surface of a coal mine can be effectively simulated, providing a more realistic test environment for testing the working performance of hydraulic supports under different terrain conditions.

[0027] The hydraulic support 3 is equipped with two second laser rangefinders on its base. The distance detected by the two first laser rangefinders at predetermined positions is used to calculate the movement distance of the push rod at a specific position, and then the rotation angle of the push rod is generated. The pushing cylinder 61 is equipped with a pressure sensor to detect the magnitude of the thrust applied by the pushing cylinder 61 to the load block 62, and then the load size is obtained by combining the pressure-bearing area of ​​the load block 62.

[0028] The foregoing has shown and described the basic principles and main features of this utility model. It is obvious to those skilled in the art that this utility model is not limited to the details of the above exemplary embodiments. Therefore, the embodiments should be regarded as exemplary and non-limiting. The scope of this utility model is defined by the appended claims rather than the foregoing description. Therefore, it is intended to include all changes that fall within the meaning and scope of the equivalents of the claims within this utility model.

[0029] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A multi-condition testing device for straightness, characterized in that, The system includes a frame (1), a controllable load mechanism, and a top plate adjustment mechanism, a hydraulic support assembly, and a bottom plate adjustment mechanism that are connected sequentially from top to bottom. The bottom plate adjustment mechanism is connected to the bottom of the frame (1). The bottom plate adjustment mechanism includes a sub-bottom plate (42) and a connecting mechanism. The sub-bottom plate (42) drives the hydraulic support assembly to rotate around the Y-axis through the connecting mechanism. The top plate adjustment mechanism abuts against the upper surface of the top beam of the frame (1). The top plate adjustment mechanism includes a top plate assembly and a rotating rod (26). The rotating rod (26) drives the top plate assembly to rotate around the X-axis, thereby driving the hydraulic support assembly to rotate around the X-axis. The controllable load mechanism is installed on the bottom plate adjustment mechanism. The controllable load mechanism includes a load block (62). The load block (62) abuts against the push rod of the hydraulic support assembly and slides on the bottom plate adjustment mechanism. The load block (62) is provided with a laser collimation sensor or a wire displacement sensor for detecting the relative posture of multiple load blocks (62).

2. The multi-condition detection type straightness testing device according to claim 1, characterized in that, The top plate adjustment mechanism also includes a first rotary cylinder (231), a third lifting cylinder (21), a lifting plate (23), a rocker arm (232), a pressure plate (27), a positioning pin (28), and a connecting piece (22). The cylinder body of the third lifting cylinder (21) is fixedly connected to the frame (1). The piston rod of the third lifting cylinder (21) drives the lifting plate (23) to move along the Z-axis on the frame (1) through the connecting piece (22). The frame (1) is provided with positioning holes (11) that are compatible with the positioning pin (28). Multiple positioning holes (11) are provided along the Z-axis. The lifting plate (23) is provided with positioning holes (11) that are compatible with the positioning pin (28). The positioning pin (28) is connected to the frame (1) by sequentially inserting the pin hole and the positioning hole (11). The lifting plate (23) has a groove formed by the bottom surface being recessed upward along the Z-axis. The rocker arm (232) is located in the groove. One end of the rocker arm (232) is hinged to the piston rod of the first rotating oil cylinder (231). The other end of the rocker arm (232) is hinged to the side of the bottom surface of the lifting plate (23) away from the first rotating oil cylinder (231). The bottom of the rocker arm (232) is fixedly connected to the top of the top plate assembly. The rocker arm (232) drives the top plate assembly to rotate around the Y-axis through the first rotating oil cylinder (231).

3. The multi-condition detection type straightness testing device according to claim 2, characterized in that, The top plate assembly includes an upper top plate (24), a lower top plate (25), and a pressure plate (27). The upper top plate (24) is disposed above the lower top plate (25). The top of the upper top plate (24) is fixedly connected to the bottom of the rocker arm (232). The rotating rod (26) extends along the X-axis and is rotatably disposed below the upper top plate (24). The upper part of the lower top plate (25) is fixedly connected to the rotating rod (26). The top of the pressure plate (27) is fixedly connected to the bottom of the lower top plate (25). The bottom of the pressure plate (27) abuts against the top of the hydraulic support assembly.

4. The multi-condition detection type straightness testing device according to claim 3, characterized in that, The controllable load mechanism also includes a load base (65) and a push cylinder (61). The load base (65) is fixedly connected to the base plate adjustment mechanism. The push cylinder (61) is arranged along the Y-axis direction. The cylinder body of the push cylinder (61) is fixedly connected to the load base (65). The piston rod of the push cylinder (61) is hinged to the load block (62).

5. The multi-condition detection type straightness testing device according to claim 4, characterized in that, The base plate adjustment mechanism also includes a base plate (41), a support rod (43) and a connector (47). The controllable load mechanism also includes a dumbbell pin (63). The base plate (41) is fixedly connected to the mounting plate at the bottom of the frame (1) through the support rod (43). The bottom of the sub-base plate (42) is hinged to the top of the base plate (41) through the connector (47). Multiple sub-base plates (42) are arranged side by side along the X-axis. The hydraulic support group includes multiple hydraulic supports (3) arranged side by side along the X-axis. Each hydraulic support (3) is set on a sub-base plate (42) and abuts against a load block (62). Multiple load blocks (62) are connected in series through dumbbell pins (63).

6. The multi-condition detection type straightness testing device according to claim 5, characterized in that, The connecting mechanism includes a connecting plate (57), a first operating lever (51), a second operating lever (53), a first lifting cylinder (52), a second lifting cylinder (54), a first connecting rod (55), and a second connecting rod (56). Each sub-base plate (42) is connected to the first connecting rod (55) and the second connecting rod (56) on the side furthest from the controllable load mechanism. The first connecting rod (55) and the second connecting rod (56) are connected to opposite sides of the sub-base plate (42). The bottoms of the first connecting rod (55) and the second connecting rod (56) are respectively connected to the second operating lever (53) and the first operating lever (51). The first operating lever (51) and the second operating lever (53) extend along the X-axis direction, and the second operating lever (54)... 3) It is set between the first control lever (51) and the hydraulic support group; the connecting plate (57) is fixedly connected to the end face of the base plate (41) away from the controllable load mechanism and extends along the X-axis direction; there are multiple first lifting cylinders (52) and second lifting cylinders (54), and they are arranged on the connecting plate (57) along the X-axis direction. The first lifting cylinder (52) and the second lifting cylinder (54) are both set along the Z-axis direction. The first control lever (51) is hinged to the top of the piston rod of the first lifting cylinder (52), and the second control lever (53) is hinged to the top of the piston rod of the second lifting cylinder (54). The piston rods of the first lifting cylinder (52) and the second lifting cylinder (54) move in opposite directions and have equal displacement.

7. The multi-condition detection type straightness testing device according to claim 5, characterized in that, The first rotary cylinder (231) is equipped with a first laser rangefinder for measuring the extension distance of the cylinder piston rod, the hydraulic support (3) base is equipped with two second laser rangefinders, and the push cylinder (61) is equipped with a pressure sensor.

8. The multi-condition detection type straightness testing device according to claim 6, characterized in that, The first control lever (51) and the second control lever (53) are both provided with sliding grooves. The sliding grooves are inverted T-shaped. The bottom of the first connecting rod (55) and the second connecting rod (56) are both provided with inverted T-shaped sliders. The inverted T-shaped sliders are engaged in the sliding grooves and slide within the sliding grooves.

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