Comprehensive tester for visual field and protection area of helmet and safety helmet

Abstract

The utility model discloses a helmet visual field and protection area comprehensive tester, which belongs to the technical field of helmet visual field and protection area testing, and comprises a base, a head mold and a control display, and the surface of the head mold is provided with a reference marking line; the mounting frame is mounted at the top of the base, and the head mold is arranged on the inner side of the mounting frame; the movable supporting assembly is mounted at the top of the base; the helmet and safety helmet visual field testing device is provided with the movable visual field testing assembly, visual field testing can be carried out on helmets and safety helmets of different models, visual field angle values of the helmets and safety helmets can be accurately tested through the angle sensor and visually displayed through the control displayer, and four sets of laser emitters are arranged in the helmet and safety helmet visual field testing device. The four-station cross cursor is used for testing the protection area of the helmet, projection surveying and mapping of the protection area can be carried out on the 360-degree curved surface of the helmet at a time, and the testing efficiency is high.

Description

Technical Field

[0001] The utility model belongs to the technical field of testing the visual field and protection area of ​​a helmet safety helmet, and in particular relates to a comprehensive testing instrument for the visual field and protection area of ​​a helmet safety helmet. Background Art

[0002] In many places such as work, life, transportation, sports, leisure and entertainment, such as construction work, mining, coal mining, excavation; driving motorcycles, racing cars, various aircraft, electric bicycles; ice and snow, equestrian, fencing, skateboarding, roller skating activities; rescue, fire fighting, anti-terrorism and explosion prevention, etc., helmets must be worn to protect the safety of the head. Typical helmets and helmets generally include a helmet shell body, a buffer layer, a wearing device system, a protective mask, etc. The helmet shell body is mainly worn on the head. Depending on the size and shape, it can protect important organs such as the head, temples, ears, mouth, nose, cheeks, and chin alone or in combination. The buffer layer and the helmet shell body mainly absorb energy, reduce shock, buffer, and disperse instantaneous impact force, so that the force acting on the head is reduced to a minimum or prevent sharp objects from directly piercing the head, thereby avoiding or reducing direct damage to the head. The wearing device system is mainly to adjust the size of the helmet and ensure that the helmet is stably worn on the head to prevent the helmet from falling off the head and losing its protective effect. The protective mask is installed on the main body of the helmet shell. The mask can be made and presented in an open or closed position relative to the main body of the helmet shell as needed. It is generally made of transparent material and its function is to prevent the intrusion of harmful particles and raindrops such as sand, dust, rain, smoke, etc., especially to prevent damage to the eyelids by branches, flying stones, and even explosives.

[0003] When helmets and safety helmets are undergoing production design experiments, they need to be tested for field of view and protection area. However, in the prior art, the field of view test of helmets and safety helmets mostly uses a fixed angle plate test method, that is, if the fixed angle plate can be put in, it is qualified, and if it cannot be put in, it is unqualified. Qualitative analysis, without accurate data, cannot conduct digital analysis and research on the field of view of helmets and safety helmets, and is not conducive to the research and development, design, and upgrade and improvement of helmets and safety helmets by helmet and safety helmet manufacturers; when testing the protection area of ​​helmets and safety helmets, there is currently no special equipment on the market, and most people use conventional instruments such as height gauges and vernier calipers to manually draw the protection area. First, the operation is inconvenient, and second, the surface of the helmet and safety helmet is a curved surface. When the curved surface size test is performed, the data is also inaccurate, resulting in inaccurate testing of the protection area.

[0004] To this end, we propose a comprehensive tester for the field of view and protection area of ​​a helmet to solve the problems existing in the prior art, so that it can quantify the field of view and directly present it digitally during the field of view test of a helmet. When testing the protection area, a four-station cross cursor is used to project the protection area of ​​the 360° curved surface of the helmet, so that the test is accurate and efficient. Utility Model Content

[0005] The utility model aims to provide a comprehensive tester for the visual field and protection area of ​​a helmet safety helmet, so as to solve the problem that in the prior art, a visual field test and a protection area test need to be performed on a helmet safety helmet during a production design experiment as mentioned in the above background technology. However, in the prior art, a fixed angle plate test method is mostly used for the visual field test of a helmet safety helmet, that is, if the fixed angle plate can be put in, it is qualified, and if it cannot be put in, it is unqualified. Qualitative analysis is performed without accurate data, and it is impossible to perform digital analysis and research on the visual field of the helmet safety helmet, which is also not conducive to the research and development, design, and upgrading and improvement of the helmet safety helmet by the helmet safety helmet manufacturers. When testing the protection area of ​​a helmet safety helmet, there is currently no special equipment on the market, and most of the conventional instruments such as a height gauge and a vernier caliper are used manually to draw the protection area manually. Firstly, the operation is inconvenient, and secondly, the surface of the helmet safety helmet is a curved surface. When the curved surface size test is performed, the data is also inaccurate, resulting in the problem of inaccurate testing of the protection area.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A comprehensive tester for the visual field and protection area of ​​a helmet safety helmet comprises a base and a head mold, wherein the surface of the head mold is provided with reference markings; a mounting frame installed on the top of the base, and the head mold is arranged on the inner side of the mounting frame; a movable support assembly installed on the top of the base, and the head mold is adjustably mounted on the top of the base through the movable support assembly; laser emitters are respectively arranged on the left side, right side, top and back of the head mold; a movable mounting assembly installed on the surface of the mounting frame for movably mounting the laser emitter on the mounting frame; a visual field test assembly installed on the front of the movable support assembly for testing the visual field angle of the helmet safety helmet; and a control switch installed on the front of the base, and the control switch is connected to the laser emitter signal.

[0008] Preferably, the movable support assembly includes a slide seat fixedly mounted on the top of the base; a slide groove opened on the top of the slide seat; a slider slidably mounted in the inner cavity of the slide groove, and a limiting assembly is arranged between the two sides of the slider and the inner wall of the slide groove; a connecting plate installed on the top of the slider; a support seat installed on the top of the connecting plate; and a positioning assembly installed on the top of the support seat for fixing the head mold and the support seat together.

[0009] Preferably, the positioning assembly includes a positioning plate fixedly mounted on the top of the support seat; a positioning rod threadedly connected to the four corners of the bottom of the positioning plate; and a positioning hole opened on the inner wall of the head mold and arranged corresponding to the positioning rod, and the top end of the positioning rod passes through the positioning plate and is threadedly connected to the inner wall of the positioning hole.

[0010] Preferably, the visual field test assembly includes an adjustment seat movably mounted on the front side of the support seat; a slot opened on the front side of the adjustment seat, the slot being L-shaped; a head shape adjustment control board detachably plugged into the inner cavity of the slot, one end of the head shape adjustment control board passing through the slot and extending to the outside of the slot; an angle sensor installed at the bottom of one end of the head shape adjustment control board, the rotating end of the angle sensor passing through the head shape adjustment control board and extending to the top of the head shape adjustment control board; and a test pointer installed at the rotating end of the angle sensor; and also includes a control display arranged on one side of the base, the control display being connected to the angle sensor signal.

[0011] Preferably, the movable mounting assembly includes a movable seat slidably mounted on the surface of the mounting frame; a mounting plate mounted on the surface of the laser emitter; and a mounting rod threadedly connected to the surface of the mounting plate, one end of the mounting rod passes through the mounting plate and extends to the outside of the mounting plate to be threadedly connected to the surface of the movable seat.

[0012] Preferably, the limiting assembly includes limiting rods fixedly mounted on both sides of the inner cavity of the slide groove; and limiting grooves opened on both sides of the sliding block, and the inner walls of the limiting grooves are slidably connected to the surfaces of the limiting rods.

[0013] Technical effects and advantages of the utility model: Compared with the prior art, the utility model provides a comprehensive tester for the visual field and protection area of ​​a helmet, which has the following advantages:

[0014] The utility model is provided with a movable visual field test component, which can be used to perform visual field tests on helmets and safety helmets of different models. By setting an angle sensor, the visual field angle value of the helmet and safety helmet can be accurately tested and intuitively displayed through a control display. In addition, four groups of laser transmitters are provided in the device, and a four-station cross cursor is used to test the protection area of ​​the helmet and safety helmet. The protection area can be projected and mapped on both sides of the helmet and safety helmet at one time, and the test efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the utility model;

[0016] Figure 2 It is a structural schematic diagram of the movable installation assembly of the utility model;

[0017] Figure 3 This is a schematic diagram of the structure of the movable support assembly of the utility model;

[0018] Figure 4 It is a structural schematic diagram of the visual field test assembly of the utility model;

[0019] Figure 5It is a structural schematic diagram of the positioning component of the utility model;

[0020] Figure 6 For this utility model Figure 4 Enlarged view of point A in the middle.

[0021] In the figure: 1. base; 2. head mold; 3. reference mark; 4. mounting frame; 5. laser transmitter; 6. control switch; 7. slide seat; 8. slide groove; 9. slider; 10. connecting plate; 11. support seat; 12. positioning plate; 13. positioning rod; 14. positioning hole; 15. adjustment seat; 16. slot; 17. head shape adjustment control board; 18. angle sensor; 19. test pointer; 20. control display; 21. moving seat; 22. mounting plate; 23. mounting rod; 24. limit rod; 25. limit groove; 26. locking seat; 27. locking rod; 28. scale line; 29. ​​fastener; 30. limit hole. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The specific embodiments described here are only used to explain the utility model and are not used to limit the utility model. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0023] See also Figure 1-Figure 6 The utility model discloses a comprehensive tester for the visual field and protection area of ​​a helmet, comprising a base 1 and a mounting frame 4 on the top of the base 1, wherein the head mold 2 is arranged on the inner side of the mounting frame 4; and a movable support assembly mounted on the top of the base 1, wherein the head mold 2 is adjustably mounted on the top of the base 1 through the movable support assembly; the movable support assembly comprises a slide seat 7 fixedly mounted on the top of the base 1; a slide groove 8 opened on the top of the slide seat 7; a slider 9 slidably mounted in the inner cavity of the slide groove 8; a connecting plate 10 mounted on the top of the slider 9; and a support seat 11 mounted on the top of the connecting plate 10.

[0024] In this embodiment, the head mold 2 can be movably installed on the top of the base 1 through the setting of the movable support component. When the position of the head mold 2 needs to be moved, the user can directly move the support seat 11. The movement of the support seat 11 will drive the slider 9 to slide in the inner cavity of the slide groove 8 through the connecting plate 10. A scale line 28 is engraved on the side of the slide seat 7, which can be used to judge the adjustment and movement position of the head mold 2.

[0025] It also includes a positioning component installed on the top of the support base 11 for fixing the head mold 2 and the support base 11 together, the positioning component includes a positioning plate 12 fixedly installed on the top of the support base 11; a positioning rod 13 threadedly connected to the four corners of the bottom of the positioning plate 12; and a positioning hole 14 opened on the inner wall of the head mold 2 and arranged corresponding to the positioning rod 13, the top end of the positioning rod 13 passes through the positioning plate 12 and is threadedly connected to the inner wall of the positioning hole 14.

[0026] In this embodiment, the head mold 2 is installed on the top of the support seat 11 through the positioning assembly. The head mold 2 is detachable and can be replaced according to the model of the test helmet. During installation, the user can place and press the head mold 2 on the top of the positioning plate 12, and then tighten the positioning rod 13 from the bottom. The rotation of the positioning rod 13 will cause the top end of the positioning rod 13 to pass through the positioning plate 12 and be threadedly connected to the positioning hole 14 on the inner wall of the head mold 2, thereby installing and fixing the use position of the head mold 2 and connecting it to the top of the support seat 11.

[0027] Furthermore, a limit assembly is arranged between the two sides of the slider 9 and the inner wall of the slide groove 8, and the limit assembly includes a limit rod 24 fixedly installed on both sides of the inner cavity of the slide groove 8; and a limit groove 25 opened on both sides of the slider 9, and the inner wall of the limit groove 25 is slidably connected to the surface of the limit rod 24.

[0028] By setting the limiting component, the slider 9 can be limited to prevent the slider 9 from slipping out of the inner cavity of the slide groove 8. In addition, by using the limiting rod 24 and the limiting groove 25 in coordination, the stability of the movement of the slider 9 can also be improved. When the slider 9 moves, the limiting groove 25 on its surface will drive it to slide on the surface of the limiting rod 24.

[0029] As a preferred embodiment, it also includes laser emitters 5 respectively arranged on the left side, right side, top and back of the head mold 2. The surface of the head mold 2 is provided with reference markings 3, including a base plane, a reference plane, a 12.7mm plane, a 44.5mm plane, a plurality of reference markings such as a front-back and left-right symmetrical planes. It also includes a control switch 6 installed on the front of the base 1. The control switch 6 is connected to the laser emitter 5 by signal. In this embodiment, a cross cursor is emitted by the laser emitter 5. In addition, four groups of cross cursors are arranged in the device, which are respectively located on the left side, right side, top and back of the head mold 2. When testing the protection area, the protection area of ​​the helmet and safety helmet can be projected and mapped on both sides at one time, and the test efficiency is high.

[0030] It is worth mentioning that it also includes a movable mounting component installed on the surface of the mounting frame 4 for movably mounting the laser emitter 5 on the mounting frame 4; the movable mounting component includes a movable seat 21 slidably mounted on the surface of the mounting frame 4; a mounting plate 22 installed on the surface of the laser emitter 5; and a mounting rod 23 threadedly connected to the surface of the mounting plate 22, one end of the mounting rod 23 passes through the mounting plate 22 and extends to the outside of the mounting plate 22 and is threadedly connected to the surface of the movable seat 21.

[0031] In this embodiment, by setting the movable mounting assembly, the laser emitter 5 can be movably mounted on the mounting frame 4, and its use position can be moved. The position of the laser emitter 5 is adjusted according to the model of the helmet and safety helmet so that the cross cursor can overlap with the reference mark 3 on the head mold 2. When adjusting the use position of the laser emitter 5, the user can directly adjust the use position of the movable seat 21. The laser emitter 5 is mounted on the movable seat 21 through the mounting rod 23 and the mounting plate 22.

[0032] In addition, locking seats 26 are installed at both ends of the movable seat 21, and the surface of the locking seat 26 is threadedly connected with a locking rod 27. After the use position of the movable seat 21 is adjusted, the user can tighten the locking rod 27. The rotation of the locking rod 27 will cause one end of the locking rod 27 to penetrate the locking seat 26 and extend to the outside of the locking seat 26 to fit with the surface of the mounting frame 4. The movable seat 21 can be pressed and fixed on the surface of the mounting frame 4 to position the use position of the laser emitter 5.

[0033] In this embodiment, the movable seat 21 is also movably arranged, and the laser emitter 5 is installed on its movable part for fine-tuning the use position of the laser emitter 5. A fastener 29 is installed on the movable part for fixing the adjusted position of the laser emitter 5. A scale line 28 is also engraved on the fixed part of the movable seat 21 for judging the adjusted position of the laser emitter 5.

[0034] It should also be noted that the field of view testing component installed on the front of the movable support component for testing the field of view angle of the helmet safety helmet includes an adjustment seat 15 movably installed on the front of the support seat 11; a slot 16 opened on the front of the adjustment seat 15, and the slot 16 is L-shaped; a head shape adjustment control board 17 detachably plugged into the inner cavity of the slot 16, one end of the head shape adjustment control board 17 passes through the slot 16 and extends to the outside of the slot 16; an angle sensor 18 installed at the bottom of one end of the head shape adjustment control board 17, the rotating end of the angle sensor 18 passes through the head shape adjustment control board 17 and extends to the top of the head shape adjustment control board 17; and a test pointer 19 installed at the rotating end of the angle sensor 18; it also includes a control display 20 arranged on one side of the base 1, and the control display 20 is connected to the angle sensor 18 signal.

[0035] By setting the visual field test component, the visual field of the helmet can be tested in the up and down and left and right directions. In this embodiment, by installing a test pointer 19 on the rotating end of the angle sensor 18, when the test pointer 19 is rotated, the angle sensor 18 will change the value, and the control display 20 will display the value change to the outside, such as Figure 1 As shown, the angle sensor 18 is in a horizontal state and is used to test the left and right visual fields of the helmet. When the upper and lower visual angles of the helmet need to be tested, the user can pull out the head shape adjustment control board 17 from the slot 16 and rotate it ninety degrees to vertically insert the head shape adjustment control board 17 into the inner cavity of the slot 16.

[0036] like Figure 6 As shown, the surface of the head shape adjustment control plate 17 is provided with a plurality of groups of limit holes 30, and the corresponding limit holes 30 are sprayed with A, E, J, M, O model identifications for selecting the correct head shape and helmet safety helmet samples for testing. In this embodiment, the head mold 2 is a half head mold of magnesium aluminum alloy, with a response frequency of <2000HZ, and is divided into extra small (A), small (E), medium (J), large (M), and extra large (0).

[0037] Based on the above-mentioned comprehensive tester for the visual field and protection area of ​​a helmet, this embodiment further discloses a test method for the comprehensive tester for the visual field and protection area of ​​a helmet, including left and right visual field tests, upper and lower visual field tests, and protection area tests, wherein:

[0038] The left and right visual field test is to test the left and right visual field of the helmet by rotating the test pointer 19 left and right. The specific test steps are as follows:

[0039] Put the helmet on the head mold 2 correctly, adjust the head shape adjustment control panel 17 and the angle sensor 18 to a horizontal state, adjust the test pointer 19 to the center position, and then click the reset button on the control display 20 to make the initial angle value zero;

[0040] Slowly push the test pointer 19 to the left edge of the helmet, and the angle displayed at this time is the corresponding left visual field;

[0041] Slowly push the test pointer 19 to the center position again, press reset, and then slowly push it to the right edge. The angle displayed at this time is the corresponding right field of view.

[0042] It is worth noting that after a test is completed, if another test is required, repeat the above steps; if not necessary, turn off the power and perform equipment maintenance.

[0043] The upper and lower visual field test is to test the upper and lower visual field of the helmet by rotating the test pointer 19 up and down. The specific test steps are as follows:

[0044] Put the helmet on the head mold 2 correctly, adjust the head shape adjustment control board 17 and the angle sensor 18 to a vertical state, and slide the angle sensor 18 to the uppermost position to contact the reference plane;

[0045] Adjust the test pointer 19 to the center position, and then click the reset button on the control display 20 to make the initial angle value zero;

[0046] Slowly push the test pointer 19 to the upper edge of the helmet, and the angle displayed at this time is the corresponding upper field of view;

[0047] Then take off the helmet, determine the distance X between the reference plane and the base plane according to the size of the helmet, and move the angle sensor 18 down by the distance X. After adjustment, put the helmet on the head mold 2 again.

[0048] Adjust the test pointer 19 to the center position, and then click the reset button on the control display 20 to make the initial angle value zero;

[0049] Slowly push the test pointer 19 to the lower edge of the helmet, and the angle displayed at this time is the corresponding lower field of view.

[0050] It is worth noting that because the Class A full-face helmet has a chin protection part and the eye observation port has four edges, the left and right and upper and lower fields of vision can be tested. For Class A half-helmets and Class B half-helmets, the chin is exposed and unprotected, there is no obstruction below, and the eyes can see the vertical ground, that is, the lower field of vision can reach 90°, so there is no need to test the lower field of vision.

[0051] In addition, when testing the left and right fields of view, the angle sensor 18 is in a horizontal position, and when testing the upper and lower fields of view, the angle sensor 18 is in a vertical position. This operation requires manual adjustment.

[0052] The protection area test uses the laser transmitter 5 to emit a cross cursor and cooperate with the head model 2 to perform projection mapping of the protection area. The specific test steps are as follows:

[0053] Turn on the four-position cross cursor, and match the cross cursors in the left, right, top, and back directions to the intersections of the central vertical axis of the head mold 2 and the reference plane respectively;

[0054] The base line of the four-dimensional reference plane can be adjusted by adjusting the scale line 28 to observe the position of the reference plane and the base plane. When adjusting, keep the intersection of the four-position cross cursor and the central vertical axis of the head mold 2 and the reference plane consistent, and then judge the position of the protection area respectively;

[0055] Taking the base plane as an example, adjust the four-position cross cursors to the base plane positions respectively, and adjust the corresponding cursor positions according to the protection ranges of the head molds 2 of different specifications and sizes;

[0056] After the protection area is determined by the four-position cross cursor, the helmet is correctly worn on the head mold 2, and the projection position of the protection area can be observed to determine whether the protection area of ​​the helmet is qualified.

[0057] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A comprehensive tester for the visual field and protection area of ​​a helmet, characterized in that: include: A base (1) and a head mold (2), wherein a reference mark line (3) is provided on the surface of the head mold (2); A mounting frame (4) mounted on the top of the base (1), the head mold (2) being arranged on the inner side of the mounting frame (4); A movable support assembly mounted on the top of the base (1), wherein the head mold (2) is adjustably mounted on the top of the base (1) via the movable support assembly; Laser emitters (5) are respectively arranged on the left side, right side, top and back of the head mold (2); A movable mounting component mounted on the surface of the mounting frame (4) for movably mounting the laser emitter (5) on the mounting frame (4); A visual field testing component installed on the front of the movable support component for testing the visual field angle of the helmet; as well as A control switch (6) is installed on the front side of the base (1), and the control switch (6) is connected to the laser emitter (5) by signal.

2. A comprehensive tester for the visual field and protection area of ​​a helmet according to claim 1, characterized in that: The movable support assembly comprises: A slide seat (7) fixedly mounted on the top of the base (1); A slide groove (8) is provided on the top of the slide seat (7); A slider (9) is slidably mounted in the inner cavity of the slide groove (8), and a limiting component is arranged between the two sides of the slider (9) and the inner wall of the slide groove (8); A connecting plate (10) mounted on the top of the slider (9); A support base (11) mounted on the top of the connecting plate (10); and A positioning component is installed on the top of the support seat (11) and is used to fix the head mold (2) and the support seat (11) together.

3. A comprehensive tester for the visual field and protection area of ​​a helmet according to claim 2, characterized in that: The positioning component comprises: A positioning plate (12) fixedly mounted on the top of the support seat (11); Positioning rods (13) threadedly connected to the four corners of the bottom of the positioning plate (12); and A positioning hole (14) is provided on the inner wall of the head mold (2) and is arranged corresponding to the positioning rod (13). The top end of the positioning rod (13) passes through the positioning plate (12) and is threadedly connected to the inner wall of the positioning hole (14).

4. A comprehensive tester for the visual field and protection area of ​​a helmet according to claim 2, characterized in that: The visual field testing assembly comprises: An adjustment seat (15) movably mounted on the front side of the support seat (11); A slot (16) is provided on the front side of the adjustment seat (15), and the slot (16) is arranged in an L shape; A head shape adjustment control board (17) is detachably plugged into the inner cavity of the slot (16), and one end of the head shape adjustment control board (17) passes through the slot (16) and extends to the outside of the slot (16); An angle sensor (18) installed at the bottom of one end of the head shape adjustment control board (17), wherein the rotating end of the angle sensor (18) passes through the head shape adjustment control board (17) and extends to the top of the head shape adjustment control board (17); and A test pointer (19) mounted on the rotating end of the angle sensor (18); It also includes a control display (20) arranged on one side of the base (1), and the control display (20) is connected to the angle sensor (18) by signal.

5. The comprehensive tester for the visual field and protection area of ​​a helmet according to claim 1, characterized in that: The active installation components include: A movable seat (21) slidably mounted on the surface of the mounting frame (4); a mounting plate (22) mounted on the surface of the laser emitter (5); and A mounting rod (23) is threadedly connected to the surface of the mounting plate (22), one end of the mounting rod (23) passes through the mounting plate (22) and extends to the outside of the mounting plate (22) to be threadedly connected to the surface of the moving seat (21).

6. A comprehensive tester for the visual field and protection area of ​​a helmet according to claim 2, characterized in that: The limiting component comprises: Limit rods (24) fixedly mounted on both sides of the inner cavity of the slide groove (8); and Limiting grooves (25) are provided on both sides of the sliding block (9), and the inner walls of the limiting grooves (25) are slidably connected to the surface of the limiting rod (24).

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