Plate concentricity detection structure

Abstract

The utility model belongs to the technical field of concentricity detection, and particularly relates to a plate concentricity detection structure which comprises a detection table. A storage groove is formed in the side wall of the top of the detection table; a guide assembly is arranged in the middle of the inner side wall of the storage groove. A pair of moving assemblies is arranged on the side wall of the top of the detection table. The pair of moving assemblies is symmetrically arranged on the two sides of the containing groove. A first telescopic rod is fixedly connected to the middle of the side wall of the moving assembly. A first fixing ring is fixed to the side wall of the top of the first telescopic rod. A first limiting knob is rotationally matched with the middle part of the inner side wall of the first fixing ring; through the arrangement of the pressing block, the connecting block, the limiting block, the elastic band and the elastic cushion, a plate in an irregular shape can be firmly fixed to the concentricity detection instrument, the plate is prevented from moving or deforming in the measurement process, the position of the positioning plate can be adjusted through the arrangement, the plate is accurately aligned with the reference axis of the detection probe, and the detection accuracy is improved. Measurement deviation caused by errors is reduced, and measurement precision and accuracy are improved.

Description

Technical Field

[0001] This utility model belongs to the field of concentricity detection technology, specifically a structure for detecting the concentricity of sheet metal. Background Technology

[0002] Sheet metal is produced by rolling, forging, rolling, or casting metal sheets, or by producing sheet-like products from non-metallic materials such as wood, plastic, glass, and composite materials. In existing technologies, besides producing standard-sized flat rectangles, sheet metal can also be processed into irregularly shaped sheets through special techniques such as cutting, bending, stretching, and welding to meet the needs of different fields.

[0003] Before the boards are put into use, they will be tested for concentricity. The boards to be tested are placed on the workbench and measured with a concentricity meter. The concentricity of the boards is analyzed based on the measurement results, and qualified products can be selected.

[0004] Through long-term use and observation, it was found that during the concentricity test of irregularly shaped boards, the boards were not placed horizontally on the test platform, which caused the readings of the testing instrument to deviate, thus failing to accurately reflect the true concentricity of the boards.

[0005] Therefore, this utility model provides a structure for detecting the concentricity of sheet metal. Utility Model Content

[0006] To overcome the shortcomings of existing technologies and solve at least one of the problems mentioned in the background art, a plate concentricity detection structure is proposed.

[0007] The technical solution adopted by this utility model to solve its technical problem is as follows: A plate concentricity detection structure of this utility model includes a detection platform; a storage groove is provided on the top side wall of the detection platform; a guide component is provided in the middle of the inner side wall of the storage groove; a pair of moving components are provided on the top side wall of the detection platform; the pair of moving components are symmetrically arranged on both sides of the storage groove; a first telescopic rod is fixedly connected to the middle of the side wall of the moving component; a first fixing ring is fixedly connected to the top side wall of the first telescopic rod; a first limiting knob is rotatably engaged in the middle of the inner side wall of the first fixing ring; a first support rod is rotatably connected to the middle of the side wall of the first limiting knob; a second fixing ring is fixedly connected to the other end of the first support rod; a second limiting knob is rotatably engaged in the middle of the inner side wall of the second fixing ring; a second support rod is rotatably connected to the middle of the side wall of the second limiting knob; a dial indicator is installed on the other end of the second support rod; a detection probe is assembled in the middle of the side wall of the dial indicator; the detection probe is located on the storage groove. The test platform has a fixing component in the middle of its side wall; an auxiliary component is provided on the inner side wall of the bottom of the storage slot; the fixing component includes multiple screws; the screws are threadedly connected to the side wall of the test platform; a pressing block is fixedly connected to the end of the screw; multiple pressing blocks are located inside the storage slot; a connecting block is fixedly connected to the other end of the screw; multiple connecting blocks are located outside the test platform; a limiting block is threadedly connected to the middle of the side wall of the screw; an elastic band is fixedly connected between adjacent pressing blocks; an elastic pad is fixed to the middle of the side wall of the pressing block; both the elastic band and the elastic pad are made of elastic material. This step, by setting up pressing blocks, connecting blocks, limiting blocks, elastic bands, and elastic pads, can firmly fix irregularly shaped plates on the concentricity testing instrument, preventing them from moving or deforming during measurement. This setup can also adjust the position of the plate, ensuring precise alignment between the plate and the reference axis of the testing probe, reducing measurement deviations caused by errors, and improving the accuracy and precision of the measurement.

[0008] Preferably, the movable component includes a groove; the groove is formed on the top of the inspection table; a threaded rod is rotatably connected to the middle of the inner sidewall of the groove; an adjusting valve is assembled at the end of the threaded rod; the adjusting valve is located outside the inspection table; a movable ring is slidably connected to the middle of the sidewall of the threaded rod; the movable ring is fixedly connected to the first telescopic rod; this step, by setting the threaded rod, adjusting valve, and movable ring, allows the inspection probe to be easily moved to different working areas for real-time, in-situ inspection of the board material, thereby improving production efficiency and product quality. Furthermore, different board material specifications and shapes require different inspection methods and equipment. The movable concentricity inspection instrument can adapt to boards of different specifications and shapes, enabling the same equipment to be used for the inspection of multiple different types of boards, reducing equipment costs and improving equipment utilization.

[0009] Preferably, the guiding component includes a pair of first slots; the pair of first slots are symmetrically opened on the side wall of the storage slot; a guide plate is rotatably connected to the middle of the inner side wall of the first slot; a channel is opened in the middle of the side wall of the guide plate; a movable block is slidably connected to the middle of the inner side wall of the channel; a second telescopic rod is rotatably connected to the middle of the side wall of the movable block; the other end of the second telescopic rod is fixed inside the first slot; this step, by setting the guide plate, channel, movable block and second telescopic rod, can guide the plate into the concentricity detection center area according to a predetermined path and position, thereby improving the positioning accuracy of the plate during the detection process and reducing the situation where positioning errors lead to inaccurate detection results.

[0010] Preferably, the auxiliary component includes a base; the base is placed inside the storage slot; a plurality of ball bearings are rotatably connected to the bottom side wall of the base; the plurality of ball bearings rotate on the side wall of the storage slot; this step, by setting the base and ball bearings, allows the board to be easily moved to the concentricity detection center area, reducing the friction between the board and the inner wall of the storage slot and protecting the surface quality of the board.

[0011] Preferably, a second groove is provided in the middle of the side wall of the guide plate; multiple rollers are rotatably connected to the middle of the inner side wall of the second groove; by setting the second groove and rollers, this step can reduce the friction between the plate and the guide plate when it moves, thereby achieving a more stable movement.

[0012] Preferably, slots are provided on the side walls of the first fixing ring, the second fixing ring, and the second support rod; the slots are hollow; this step, by providing slots, can reduce the resistance generated by friction between the first fixing ring, the first limiting knob, the first support rod, the second fixing ring, the second limiting knob, and the second support rod, which helps to prevent the material properties from deteriorating or being damaged due to the heat generated by friction, and improves the overall operating efficiency.

[0013] The beneficial effects of this utility model are as follows:

[0014] 1. The plate concentricity detection structure of this utility model, by setting up a pressing block, a connecting block, a limiting block, an elastic band and an elastic pad, can firmly fix irregularly shaped plates on the concentricity detection instrument, preventing them from moving or deforming during the measurement process. In addition, this setting can also adjust the position of the plate to make the plate precisely aligned with the reference axis of the detection probe, reduce measurement deviation caused by errors, and improve the accuracy and precision of the measurement.

[0015] 2. The plate concentricity detection structure described in this utility model, by setting a threaded rod, adjusting valve and movable ring, allows the detection probe to be easily moved to different working areas for real-time, in-situ detection of the plate, thereby improving production efficiency and product quality. Moreover, different plate specifications and shapes require different detection methods and equipment. The movable concentricity detection instrument can adapt to plates of different specifications and shapes, enabling the same equipment to be used for the detection of multiple types of plates, reducing equipment costs and improving equipment utilization. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] Figure 1 This is a perspective view of the present invention;

[0018] Figure 2 This is a schematic diagram of the cooperative structure of the detection probe and the guide plate in this utility model;

[0019] Figure 3 This is a cross-sectional view of the storage compartment in this utility model;

[0020] Figure 4 This is a schematic diagram of the cooperation structure between the limit knob and the support rod in this utility model.

[0021] Legend:

[0022] 1. Testing platform; 11. Storage slot; 12. First telescopic rod; 13. First fixing ring; 14. First limit knob; 15. First support rod; 16. Second fixing ring; 17. Second limit knob; 18. Second support rod; 19. Dial indicator; 110. Testing probe; 2. Screw; 21. Pressing block; 22. Connecting block; 23. Limiting block; 24. Elastic band; 25. Elastic pad; 3. Groove; 31. Threaded rod; 32. Adjusting valve; 33. Movable ring; 4. First slot; 41. Guide plate; 42. Channel; 43. Movable block; 44. Second telescopic rod; 5. Base; 51. Ball bearing; 6. Second slot; 61. Roller; 7. Hole. Detailed Implementation

[0023] 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 skilled in the art without creative effort are within the protection scope of the present utility model.

[0024] Specific implementation examples are given below.

[0025] like Figures 1 to 4 As shown, an embodiment of the present invention provides a plate concentricity detection structure, including a detection platform 1; a storage groove 11 is provided on the top side wall of the detection platform 1; a guide component is provided in the middle of the inner side wall of the storage groove 11; a pair of moving components are provided on the top side wall of the detection platform 1; the pair of moving components are symmetrically arranged on both sides of the storage groove 11; a first telescopic rod 12 is fixedly connected to the middle of the side wall of the moving component; a first fixing ring 13 is fixed to the top side wall of the first telescopic rod 12; a first limiting knob 14 is rotatably engaged in the middle of the inner side wall of the first fixing ring 13; a first support rod 1 is rotatably connected to the middle of the side wall of the first limiting knob 14. 5; A second fixing ring 16 is fixedly connected to the other end of the first support rod 15; A second limiting knob 17 is rotatably fitted to the middle of the inner side wall of the second fixing ring 16; A second support rod 18 is rotatably connected to the middle of the side wall of the second limiting knob 17; A dial indicator 19 is installed at the other end of the second support rod 18; A detection probe 110 is assembled in the middle of the side wall of the dial indicator 19; The detection probe 110 is located above the storage slot 11; A fixing component is provided in the middle of the side wall of the detection table 1; An auxiliary component is provided on the inner side wall of the bottom of the storage slot 11; During operation, the inspector adjusts the spacing of the guide components and then places the irregular shape to be inspected. The board material is placed on the auxiliary component inside the storage slot 11, and then pushed with the assistance of the auxiliary component. At this time, the board material to be tested will move along the central area of ​​the storage slot 11 under the action of the guide component. When the irregularly shaped board material moves to the testing area, the operator observes the shape of the board material and uses the fixing component to limit it to the same horizontal line. Then, the moving component is used to adjust the position of a pair of first telescopic rods 12, and at the same time, the detection probe 110 is pulled, so that the detection probe 110 is suspended at the testing position. When the detection probe 110 moves, it will move the dial indicator 19. When the dial indicator 19 moves, the second support rod 18 will rotate on the side wall of the second limit knob 17. At the same time, when the second support rod 18 moves under the drive of the dial indicator 19, it will drive the first support rod 15 and the second fixing ring 16 to rotate on the first limit knob 14. After the position of the detection probe 110 is fixed, the first limit knob 14 and the second limit knob 17 are used to lock the positions of the first telescopic rod 12, the first fixing ring 13, the first support rod 15, the second fixing ring 16 and the second support rod 18 respectively. Then, the detection probe 110 is used to detect the concentricity of the plate.

[0026] like Figures 1 to 3As shown, the fixing assembly includes multiple screws 2; the screws 2 are threadedly connected to the side wall of the testing table 1; a pressing block 21 is fixedly connected to one end of the screw 2; multiple pressing blocks 21 are all located inside the storage slot 11; a connecting block 22 is fixedly connected to the other end of the screw 2; multiple connecting blocks 22 are all located outside the testing table 1; a limit block 23 is threadedly connected to the middle of the side wall of the screw 2; an elastic band 24 is fixedly connected between adjacent pressing blocks 21; an elastic pad 25 is fixed to the middle of the side wall of the pressing block 21; both the elastic band 24 and the elastic pad 25 are made of elastic material; when an irregularly shaped plate moves to the testing area, the testing personnel observe the shape of the plate and rotate multiple connecting blocks 22. When the connecting blocks 22 rotate, they will drive the screws 2 to rotate. At this time, the screws 2 will rotate and move on the side wall of the testing table 1, while the screws 2 When the device moves, it pushes the pressing block 21 to move, which in turn drives the elastic pads 25 to move synchronously. At this time, multiple elastic pads 25 will press on different positions of the board, adjusting the board to a horizontal state, which is convenient for the detection probe 110 to perform concentricity detection. At the same time, the elastic band 24 will wrap around the surface of the board to fix the position of the board. This step, by setting up the pressing block 21, connecting block 22, limiting block 23, elastic band 24 and elastic pads 25, can firmly fix the irregularly shaped board on the concentricity detection instrument, preventing it from moving or deforming during the measurement process. In addition, this setting can also adjust the position of the positioning board, so that the board is precisely aligned with the reference axis of the detection probe 110, reducing measurement deviation caused by errors and improving the accuracy and precision of the measurement.

[0027] like Figures 1 to 4 As shown, the moving component includes a groove 3; the groove 3 is formed on the top of the testing table 1; a threaded rod 31 is rotatably connected to the middle of the inner side wall of the groove 3; an adjusting valve 32 is assembled at the end of the threaded rod 31; the adjusting valve 32 is located outside the testing table 1; a movable ring 33 is slidably connected to the middle of the side wall of the threaded rod 31; the movable ring 33 and the first telescopic rod 12 are fixedly connected; during operation, the testing personnel rotate a pair of adjusting valves 32, which will drive the threaded rod 31 to rotate inside the groove 3. When the threaded rod 31 rotates, the movable ring 33 on its side wall will slide along the threaded rod 31. When the movable ring 33 moves, it will drive the first telescopic rod 12 to move together. The first telescopic rod 12 moves, which in turn drives the detection probe 110 to move synchronously. This step, through the setting of threaded rod 31, regulating valve 32 and movable ring 33, allows the detection probe 110 to be easily moved to different working areas to perform real-time, in-situ detection of the board material, thereby improving production efficiency and product quality. Moreover, different board material specifications and shapes require different detection methods and equipment. The movable concentricity detection instrument can adapt to board materials of different specifications and shapes, enabling the same equipment to be used for the detection of multiple different types of board materials, reducing equipment costs and improving equipment utilization.

[0028] like Figures 1 to 3As shown, the guide assembly includes a pair of first slots 4; the pair of first slots 4 are symmetrically opened on the side wall of the storage slot 11; a guide plate 41 is rotatably connected to the middle of the inner side wall of the first slot 4; a channel 42 is opened in the middle of the side wall of the guide plate 41; a movable block 43 is slidably connected to the middle of the inner side wall of the channel 42; a second telescopic rod 44 is rotatably connected to the middle of the side wall of the movable block 43; the other end of the second telescopic rod 44 is fixed inside the first slot 4; during operation, the inspector pulls the pair of guide plates 41 according to the width of the material, so that the distance between the pair of guide plates 41 is just full. As the guide plate 41 moves, the movable block 43 on its side wall slides along the channel 42, and the second telescopic rod 44 changes its extension length as the position of the guide plate 41 changes, thereby fixing the position of the guide plate 41. This step, by setting the guide plate 41, channel 42, movable block 43 and second telescopic rod 44, can guide the plate into the concentricity detection center area according to the predetermined path and position, thereby improving the positioning accuracy of the plate during the detection process and reducing the situation where positioning errors lead to inaccurate detection results.

[0029] like Figure 1 and Figure 3 As shown, the auxiliary component includes a base 5; the base 5 is placed inside the storage slot 11; multiple balls 51 are rotatably connected to the bottom side wall of the base 5; the multiple balls 51 rotate on the side wall of the storage slot 11; during operation, the inspector places the plate on top of the base 5 and pushes the plate, at which time the plate will drive the base 5 and the balls 51 to move together. This step, by setting the base 5 and the balls 51, allows the plate to be easily moved to the concentricity detection center area, reducing the friction between the plate and the inner wall of the storage slot 11 and protecting the surface quality of the plate.

[0030] like Figure 1 and Figure 3 As shown, a second slot 6 is provided in the middle of the side wall of the guide plate 41; multiple rollers 61 are rotatably connected to the middle of the inner side wall of the second slot 6; during operation, the plate will first contact the multiple rollers 61 on the side wall of the guide plate 41 and move under the push of the rollers 61. This step, by setting the second slot 6 and the rollers 61, can reduce the friction between the plate and the guide plate 41 when moving, thereby achieving a more stable movement.

[0031] like Figure 1 , Figure 2 and Figure 4As shown, slots 7 are provided on the side walls of the first fixing ring 13, the second fixing ring 16, and the second support rod 18; the slots 7 are hollow structures; during operation, when the rotation between the first fixing ring 13, the first limiting knob 14, the first support rod 15, the second fixing ring 16, the second limiting knob 17, and the second support rod 18 becomes stuck, the inspector injects lubricating oil into the slots 7. This step, by setting the slots 7, can reduce the resistance generated by friction between the first fixing ring 13, the first limiting knob 14, the first support rod 15, the second fixing ring 16, the second limiting knob 17, and the second support rod 18, which helps to prevent the material properties from deteriorating or being damaged due to the heat generated by friction, and improves the overall operating efficiency.

[0032] Working principle: The inspector adjusts the spacing of the guide components, then places the irregularly shaped sheet material to be inspected on the auxiliary components inside the storage slot 11. With the assistance of the auxiliary components, the sheet material is pushed, moving along the central area of ​​the storage slot 11 under the action of the guide components. When the irregularly shaped sheet material reaches the inspection area, the operator observes its shape and uses the fixing components to keep it on the same horizontal line. Then, the moving components are used to adjust the position of the pair of first telescopic rods 12, while simultaneously pulling the inspection probe 110, causing it to hover at the inspection position. As the inspection probe 110 moves, it carries the dial indicator 19 along with it. The movement of the dial indicator 19 causes the second support rod 18 to move towards the second limit knob 17. As the second support rod 18 moves under the influence of the dial indicator 19, it causes the first support rod 15 and the second fixing ring 16 to rotate on the first limit knob 14. After the position of the detection probe 110 is fixed, the first limit knob 14 and the second limit knob 17 are used to lock the positions of the first telescopic rod 12, the first fixing ring 13, the first support rod 15, the second fixing ring 16, and the second support rod 18, respectively. Then, the detection probe 110 is used to detect the concentricity of the plate. When the irregularly shaped plate moves to the area to be tested, the inspector observes the shape of the plate and rotates multiple connecting blocks 22. When the connecting blocks 22 rotate, they drive the screw 2 to rotate. At this time, the screw 2 will rotate and move on the side wall of the detection table 1. The pressing block 21 will move, and when the pressing block 21 moves, it will cause the elastic pads 25 to move synchronously. At this time, multiple elastic pads 25 will press on different positions of the board, adjusting the board to a horizontal state, which is convenient for the detection probe 110 to perform concentricity detection. At the same time, the elastic band 24 will wrap around the surface of the board, fixing the position of the board. The inspector will turn a pair of regulating valves 32, which will cause the threaded rod 31 to rotate inside the groove 3. When the threaded rod 31 rotates, the movable ring 33 on its side wall will slide along the threaded rod 31. When the movable ring 33 moves, it will cause the first telescopic rod 12 to move synchronously. When the first telescopic rod 12 moves, it will cause the detection probe 110 to move synchronously. The inspector will pull a pair of guide plates 41 according to the width of the board, so that the pair of guide plates 41 can move synchronously. The distance between the guide plates 41 is just enough to allow the plate to pass through. When the guide plate 41 moves, the movable block 43 on its side wall slides along the channel 42. At the same time, the second telescopic rod 44 changes its extension length as the position of the guide plate 41 changes, thereby fixing the position of the guide plate 41. After the inspector places the plate on top of the base 5, he pushes the plate. At this time, the plate will drive the base 5 and the ball bearing 51 to move together. The plate will first contact the multiple rollers 61 on the side wall of the guide plate 41 and move under the push of the rollers 61. When the rotation between the first fixing ring 13, the first limit knob 14, the first support rod 15, the second fixing ring 16, the second limit knob 17 and the second support rod 18 becomes stuck, the inspector injects lubricating oil into the slot 7.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A plate concentricity detection structure, comprising a detection table (1); characterized in that: The detection platform (1) top side wall is provided with a storage groove (11); the inner side wall of the storage groove (11) is provided with a guide assembly; the detection platform (1) top side wall is provided with a pair of moving assemblies; a pair of the moving assemblies are symmetrically arranged on both sides of the storage groove (11); the moving assembly side wall middle part is fixedly connected with a first telescopic rod (12); the first telescopic rod (12) top side wall is fixedly connected with a first fixed ring (13); the first fixed ring (13) inner side wall middle part is rotatably connected with a first limiting knob (14); the first limiting knob (14) side wall middle part is rotatably connected with a first support rod (15); the other end of the first support rod (15) is fixedly connected with a second fixed ring (16); the second fixed ring (16) inner side wall middle part is rotatably connected with a second limiting knob (17); the second limiting knob (17) side wall middle part is rotatably connected with a second support rod (18); the other end of the second support rod (18) is provided with a micrometer (19); the micrometer (19) side wall middle part is provided with a detection probe (110); the detection probe (110) is arranged above the storage groove (11); the detection platform (1) side wall middle part is provided with a fixed assembly; the storage groove (11) bottom inner side wall is provided with an auxiliary assembly.

2. The plate concentricity detection structure according to claim 1, characterized in that: The fixed assembly comprises a plurality of screw rods (2); the screw rods (2) are threadedly connected on the side wall of the detection platform (1); the end of the screw rod (2) is fixedly connected with a pressing block (21); a plurality of the pressing blocks (21) are arranged inside the storage groove (11); the other end of the screw rod (2) is fixedly connected with a connecting block (22); a plurality of the connecting blocks (22) are arranged outside the detection platform (1); the middle part of the side wall of the screw rod (2) is threadedly connected with a limiting block (23); the adjacent pressing blocks (21) are fixedly connected with an elastic belt (24); the middle part of the side wall of the pressing block (21) is fixedly connected with an elastic pad (25); the elastic belt (24) and the elastic pad (25) are both made of elastic material.

3. The plate concentricity detection structure according to claim 1, characterized in that: The moving assembly comprises a groove (3); the groove (3) is arranged on the top of the detection platform (1); the inner side wall of the groove (3) is rotatably connected with a threaded rod (31); the end of the threaded rod (31) is provided with an adjusting valve (32); the adjusting valve (32) is arranged outside the detection platform (1); the middle part of the side wall of the threaded rod (31) is slidably connected with a movable ring (33); the movable ring (33) and the first telescopic rod (12) are fixedly connected.

4. The plate concentricity detection structure according to claim 1, characterized in that: The guide assembly comprises a pair of first notches (4); a pair of the first notches (4) are symmetrically arranged on the side wall of the storage groove (11); the inner side wall of the first notch (4) is rotatably connected with a guide plate (41); the middle part of the side wall of the guide plate (41) is provided with a groove (42); the inner side wall of the groove (42) is slidably connected with a movable block (43); the middle part of the side wall of the movable block (43) is rotatably connected with a second telescopic rod (44); the other end of the second telescopic rod (44) is fixedly connected inside the first notch (4).

5. The plate concentricity detection structure according to claim 1, characterized in that: The auxiliary assembly comprises a base (5); the base (5) is placed inside a storage groove (11); a plurality of rolling balls (51) are rotationally connected to the bottom side wall of the base (5); and the plurality of rolling balls (51) rotate on the side wall of the storage groove (11).

6. The plate concentricity detection structure according to claim 4, characterized in that: A second notch (6) is formed in the middle of the side wall of the guide plate (41); and a plurality of rolling wheels (61) are rotationally connected to the middle of the inner side wall of the second notch (6).

7. The plate concentricity detection structure according to claim 1, characterized in that: A slot hole (7) is formed in the side wall of the first fixing ring (13), the second fixing ring (16) and the second supporting rod (18); and the slot hole (7) is provided in a hollow structure.

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