An angle adjustable trench pipe assembly
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- QINGDAO TIANLUPING METAL PROD CO LTD
- Filing Date
- 2025-06-16
- Publication Date
- 2026-07-21
Smart Images

Figure CN224533662U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of pipe fittings technology, and in particular relates to an adjustable-angle grooved pipe fitting assembly. Background Technology
[0002] Grooved pipe fittings are a new type of steel pipe connection component that uses clamp connection technology. Also known as grooved pipe fittings, they have technical advantages such as easy operation, strong sealing, and efficient installation. They are now widely used in fire protection, water supply and drainage and other pipeline systems.
[0003] Chinese patent CN213225893U discloses an adjustable grooved pipe clamping device. The patent describes a device comprising: a housing with a connecting shaft passing through its center; a driven gear fixedly connected to the top of the connecting shaft; a rotary motor welded to the top surface of the housing; a rotary gear meshing with the driven gear welded to the output end of the rotary motor; rotating blocks fixedly connected to both sides of the connecting shaft; rotating blocks positioned inside rotating grooves; the bottom of the rotating grooves fixedly connected to the top surface of the housing; an inverted U-shaped frame welded to the bottom of the connecting shaft; symmetrically arranged connecting columns on the lower top surface of the inverted U-shaped frame; the tops of the connecting columns welded to the lower surface of the inverted U-shaped frame; a horizontal plate welded between the bottoms of the two connecting columns; a hollow block slidably connected to the lower bottom surface of the horizontal plate; and a slider fixedly installed on the upper top surface of the hollow block. The cavity block has an internal groove for the slider to slide. A hydraulic rod is fixedly connected to the outer wall of the cavity block near the inverted U-shaped frame. The other end of the hydraulic rod is welded to the inner surface of the inverted U-shaped frame. A first rotary motor is installed inside the cavity block and is welded to the inner wall of the cavity block near the hydraulic rod. A first transmission rod is fixedly connected to the output end of the first rotary motor. The first transmission rod is fixedly connected to the pad plate. ... The rotary motor is controlled by a switch to drive the rotary gear to rotate. The rotation of the rotary gear drives the driven gear to rotate. The driven gear drives the connecting shaft to rotate, thereby driving the inverted U-shaped frame to rotate. The clamping angle is changed by rotating the inverted U-shaped frame. 2. The extension and retraction of the hydraulic rod causes the cavity block to slide, changing the clamping distance. The first rotary motor is controlled by a switch to drive the first transmission rod to rotate. The rotation of the first transmission rod drives the clamping plate to rotate, realizing fine adjustment of the clamping angle.
[0004] However, existing clamping assemblies for grooved pipe fittings can only clamp the pipe. If the pipe needs to be clamped before installation, the entire housing is located outside the pipe. After installation, it needs to be moved to one end of the pipe to detach it, which is quite troublesome. Therefore, it is necessary to design an adjustable-angle grooved pipe fitting assembly. Utility Model Content
[0005] This utility model provides an adjustable-angle grooved pipe fitting assembly, which aims to solve the problem that if the pipe needs to be clamped for installation, the entire housing is located outside the pipe, and after installation, it needs to be moved to one end of the pipe, which is quite troublesome.
[0006] This utility model is implemented as follows: an adjustable-angle grooved pipe fitting assembly includes a limiting cylinder two; pneumatic telescopic rods four are fixedly connected to both sides of the bottom of the limiting cylinder two; a pneumatic telescopic rod three is fixedly connected to the center of the bottom of the limiting cylinder two; rotating plates are provided at the bottom of both sides of the pneumatic telescopic rods four; a T-shaped groove is formed on the outer arc-shaped surface inside the rotating plate; a T-shaped limiting rod is fixedly connected to the bottom of the pneumatic telescopic rod four, and the T-shaped limiting rod is restricted to sliding inside the T-shaped groove; a fixing plate two is fixedly connected to the bottom of the pneumatic telescopic rod three; positioning pins are provided through both sides of the inside of the fixing plate two, and the positioning pins respectively penetrate the inside of the two rotating plates; the positioning pins are fixedly connected to the fixing plate two; the positioning pins are slidably connected inside the rotating plates; rotating clamps are rotatably connected to the bottom of both rotating plates; the two rotating plates are far apart from each other. Both sides of the retaining cylinder are fixedly connected to L-shaped fixing plates. Inside each L-shaped fixing plate is a pneumatic telescopic rod five, the extension end of which faces the rotating clamping plate. Both sides of the retaining cylinder two are provided with support frames, and both sides of the support frames are provided with displacement mechanisms. By extending the pneumatic telescopic rod three or four, the opening angle of the rotating plate clamping opening can be adjusted. During the extension and retraction of the pneumatic telescopic rod three or four, the T-shaped limiting rod at the bottom of the pneumatic telescopic rod four can adapt to the sliding adjustment angle inside the rotating plate. Activating the pneumatic telescopic rod five can support the clamping position of the rotating clamping plate after rotation, thereby making the clamping process of the pipe more stable. The retaining cylinder two is supported by the support frame, and the moving and conveying is carried out by the support frame and the displacement mechanism, which can facilitate the movement and placement of grooved pipe fittings.
[0007] Preferably, it further includes a support mechanism, which includes a frame, a limiting cylinder, a pneumatic telescopic rod, an L-shaped fixing rod, and a pneumatic telescopic rod 2. The pneumatic telescopic rod 2 is fixedly connected to both sides inside the limiting cylinder 2. The extended end of the pneumatic telescopic rod 2 is fixedly connected to an L-shaped fixing rod. The other end of the L-shaped fixing rod is fixedly connected to the pneumatic telescopic rod 1. The limiting cylinder 1 is fixedly connected to the outside of the pneumatic telescopic rod 1. The frame is fixedly connected to the bottom of the limiting cylinder 1. The displacement mechanism is distributed on both sides of the top of the frame.
[0008] Preferably, the two sides of the L-shaped fixing rod are respectively adapted to be inserted into the interior of the limiting cylinder 2 and the limiting cylinder 1. By activating the pneumatic telescopic rod 1 and the pneumatic telescopic rod 2, the distance between the support mechanism and the rotating plate can be adjusted, thereby enabling clamping above buried pipe trenches of different sizes.
[0009] Preferably, the device also includes a moving mechanism, which includes a slot, rollers, and a motor. The slots are located on both sides of the frame. The rollers are rotatably connected inside the frame. The motors are fixedly connected to both ends of the outer side of the frame. The output end of the motor is fixedly connected to the rollers. By starting the motor, the rollers can be rotated, thereby moving the entire device.
[0010] Preferably, the rollers are distributed at both ends inside the two side frames, and the limiting cylinder is located between the two side rollers.
[0011] Preferably, a fixed push plate is fixedly connected to the extended end of the pneumatic telescopic rod five, and a pressure-resistant steel plate is fixedly connected to the other side of the fixed push plate. An anti-slip layer is fixedly connected to the outer side of the rotating clamping plate, and the pressure-resistant steel plate slides in contact with the anti-slip layer. By extending the pneumatic telescopic rod five, the rotating clamping plate can be inserted into both sides of the pipe fitting and then stably clamped and supported by the fixed push plate and the pressure-resistant steel plate.
[0012] Preferably, the pressure-resistant steel plate and the anti-slip layer are fitted together, the opposite surfaces of the two rotating clamps are flat, the two rotating clamps are triangular prisms, the cross-section of the rotating clamps is an equilateral triangle, the two opposite surfaces of the two rotating clamps are two symmetrical and equal surfaces of an equilateral triangular prism, and one corner of the rotating clamp is downward to facilitate insertion into both sides of the pipe fitting.
[0013] Preferably, the support frame and displacement mechanism are symmetrically arranged on both sides of the limiting cylinder.
[0014] Preferably, the top of the rotating clamp is provided with a hinge, and the rotating clamp is rotatably connected to the rotating plate through the hinge. The T-shaped groove is opened in the middle of the outer side of the rotating plate.
[0015] Preferably, a fixing piece is provided on both sides of the rotating plate, and positioning pins on both sides pass through the inside of the fixing piece, and the two ends of the fixing piece are respectively attached to the two sides of the rotating plate.
[0016] Compared with related technologies, the adjustable-angle grooved pipe fitting assembly provided by this utility model has the following beneficial effects:
[0017] 1. The opening angle of the rotating plate clamping opening can be adjusted by extending pneumatic telescopic rod three or four. During the extension and retraction of pneumatic telescopic rod three or four, the T-shaped limiting rod at the bottom of pneumatic telescopic rod four can adapt to the sliding adjustment angle inside the rotating plate. Activating pneumatic telescopic rod five can support the clamping position after the rotating clamping plate rotates, thereby making the clamping process of the pipeline more stable. The limiting cylinder two is supported by the support frame, and the moving and conveying is carried out by the support frame and the displacement mechanism, which can facilitate the movement and placement of grooved pipe fittings.
[0018] 2. By activating pneumatic telescopic rod one and pneumatic telescopic rod two, the distance between the support mechanism and the rotating plate can be adjusted, thereby enabling clamping above buried pipe trenches of different sizes. By activating the motor, the rollers can be rotated, thus moving the entire equipment. By extending pneumatic telescopic rod five, the rotating clamping plate can be inserted into both sides of the pipe fitting, and then stably clamped and supported by the fixed push plate and pressure-resistant steel plate. One corner of the rotating clamping plate faces downwards, which facilitates insertion into both sides of the pipe fitting. Attached Figure Description
[0019] Figure 1 This is a three-dimensional structural diagram of the present invention;
[0020] Figure 2 This is a side view of the structure of this utility model;
[0021] Figure 3 This is a side view of the internal structure of this utility model;
[0022] Figure 4 This utility model Figure 1 Enlarged structural diagram at point A;
[0023] Figure 5 This utility model Figure 1 Enlarged diagram of point B in the middle.
[0024] In the diagram: 1. Frame; 2. Groove; 3. Roller; 4. Motor; 5. Limiting cylinder one; 6. Pneumatic telescopic rod one; 7. L-shaped fixing rod; 8. Limiting cylinder two; 9. Pneumatic telescopic rod two; 10. Pneumatic telescopic rod three; 11. Pneumatic telescopic rod four; 12. T-shaped limiting rod; 13. Turning plate; 14. T-shaped groove; 15. Hinge; 16. Rotating clamp; 17. Anti-slip layer; 18. L-shaped fixing plate; 19. Pneumatic telescopic rod five; 20. Fixed push plate; 21. Pressure-resistant steel plate; 22. Positioning pin; 23. Fixing plate one; 24. Fixing plate two. Detailed Implementation
[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.
[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0027] Example 1
[0028] A preferred embodiment of the adjustable-angle grooved pipe fitting assembly provided by this utility model is, for example... Figures 1 to 5 As shown: An adjustable-angle grooved pipe fitting assembly includes a limiting cylinder 2 8; pneumatic telescopic rods 4 11 are fixedly connected to both sides of the bottom of the limiting cylinder 2 8; a pneumatic telescopic rod 3 10 is fixedly connected to the center of the bottom of the limiting cylinder 2 8; a rotating plate 13 is provided at the bottom of each of the two pneumatic telescopic rods 4 11; a T-shaped groove 14 is formed on the outer arc surface inside the rotating plate 13; a T-shaped limiting rod 12 is fixedly connected to the bottom of the pneumatic telescopic rods 4 11, and the T-shaped limiting rod 12 is restricted to sliding inside the T-shaped groove 14; a fixing plate 24 is fixedly connected to the bottom of the pneumatic telescopic rod 3 10; and a fixing plate 24 is fixedly connected inside the fixing plate 24. Positioning pins 22 are provided through both sides of the part, and the positioning pins 22 penetrate the interior of the rotating plates 13 on both sides respectively. The positioning pins 22 are fixedly connected to the fixing plate 24. The positioning pins 22 are slidably connected inside the rotating plate 13. Rotating clamps 16 are rotatably connected to the bottom of the rotating plates 13 on both sides. L-shaped fixing plates 18 are fixedly connected to the two sides of the rotating plates 13 that are far apart from each other. Pneumatic telescopic rod 19 is fixedly connected inside the L-shaped fixing plate 18. The extension end of the pneumatic telescopic rod 19 faces the rotating clamp 16. Support frames are provided on both sides of the limiting cylinder 28. Displacement mechanisms are provided on both sides of the support frames.
[0029] It should be noted that some existing adjustable-angle grooved pipe fittings still have certain shortcomings in actual use. They can only clamp the pipe. If the pipe needs to be clamped before installation, the entire housing is located outside the pipe. After installation, it needs to be moved to one end of the pipe to detach it from the pipe, which is quite troublesome.
[0030] In this embodiment, the opening angle of the clamping opening of the rotating plate 13 can be adjusted by extending the pneumatic telescopic rod three 10 or the pneumatic telescopic rod four 11. During the extension and retraction of the pneumatic telescopic rod three 10 or the pneumatic telescopic rod four 11, the T-shaped limiting rod 12 at the bottom of the pneumatic telescopic rod four 11 can adapt to the sliding adjustment angle inside the rotating plate 13. Activating the pneumatic telescopic rod five 19 can support the clamping position of the rotating clamping plate 16 after rotation, thereby making the clamping process of the pipeline more stable. The limiting cylinder two 8 is supported by the support frame, and the moving and conveying is carried out by the support frame and the displacement mechanism, which can facilitate the movement and placement of the grooved pipe fittings.
[0031] In a further preferred embodiment of this utility model, the support mechanism includes a frame 1, a limiting cylinder 5, a pneumatic telescopic rod 6, an L-shaped fixing rod 7, and a pneumatic telescopic rod 9. The pneumatic telescopic rod 9 is fixedly connected to both sides inside the limiting cylinder 6. The extended end of the pneumatic telescopic rod 9 is fixedly connected to the L-shaped fixing rod 7. The other end of the L-shaped fixing rod 7 is fixedly connected to the pneumatic telescopic rod 6. The limiting cylinder 5 is fixedly connected to the outside of the pneumatic telescopic rod 6. The frame 1 is fixedly connected to the bottom of the limiting cylinder 5. The displacement mechanism is distributed on both sides of the top of the frame 1.
[0032] In a further preferred embodiment of this utility model, the two sides of the L-shaped fixing rod 7 are respectively adapted to be inserted into the interior of the limiting cylinder 2 8 and the limiting cylinder 1 5.
[0033] In this embodiment, by activating the pneumatic telescopic rod 6 and the pneumatic telescopic rod 9, the distance between the support mechanism and the rotating plate 13 can be adjusted, thereby enabling clamping above buried pipe trenches of different sizes.
[0034] In a further preferred embodiment of the present invention, the moving mechanism includes a slot 2, a roller 3 and a motor 4. The slot 2 is opened on both sides of the frame 1. The roller 3 is rotatably connected inside the frame 1. The motor 4 is fixedly connected to both ends of the outer side of the frame 1. The output end of the motor 4 is fixedly connected to the roller 3.
[0035] In this embodiment, starting the motor 4 will cause the roller 3 to rotate, thereby moving the entire device.
[0036] Example 2
[0037] Based on Embodiment 1, a preferred embodiment of the adjustable-angle grooved pipe fitting assembly provided by this utility model is, for example... Figures 1 to 5 As shown: Rollers 3 are distributed at both ends inside the two side frames 1, and limiting cylinder 5 is located between the two side rollers 3.
[0038] In a further preferred embodiment of the present invention, a fixed push plate 20 is fixedly connected to the extension end of the pneumatic telescopic rod 19, and a pressure-resistant steel plate 21 is fixedly connected to the other side of the fixed push plate 20. An anti-slip layer 17 is fixedly connected to the outer side of the rotating clamp 16, and the pressure-resistant steel plate 21 slides in contact with the anti-slip layer 17.
[0039] In this embodiment, by extending the pneumatic telescopic rod 19, the rotating clamping plate 16 can be inserted into both sides of the pipe fitting and then stably clamped and supported by the fixed push plate 20 and the pressure-resistant steel plate 21.
[0040] In a further preferred embodiment of this utility model, the pressure-resistant steel plate 21 and the anti-slip layer 17 are fitted together, the opposite surfaces of the rotating clamps 16 on both sides are planes, the rotating clamps 16 on both sides are triangular prisms, the cross section of the rotating clamps 16 is an equilateral triangle, and the two opposite surfaces of the rotating clamps 16 on both sides are two symmetrical and equal surfaces of an equilateral triangular prism.
[0041] In this embodiment, rotating one corner of the clamp 16 downwards facilitates insertion into both sides of the pipe fitting.
[0042] In a further preferred embodiment of this utility model, the support frame and the displacement mechanism are symmetrically arranged on both sides of the limiting cylinder 8.
[0043] In a further preferred embodiment of the present invention, a hinge 15 is provided on the top of the rotating clamp 16, and the rotating clamp 16 is rotatably connected to the rotating plate 13 through the hinge 15. The T-shaped groove 14 is opened in the middle of the outer side of the rotating plate 13.
[0044] In a further preferred embodiment of the present invention, a fixing piece 23 is provided on both sides of the rotating plate 13, and the positioning pins 22 on both sides pass through the two sides inside the fixing piece 23 respectively. The two ends of the fixing piece 23 are respectively attached to the two sides of the rotating plate 13.
[0045] In summary, by activating pneumatic telescopic rods 6 and 9, the distance between the support mechanism and the rotating plate 13 can be adjusted, allowing for clamping above buried pipe trenches of different sizes. Activating motor 4 causes roller 3 to rotate, thus moving the entire device. Extending pneumatic telescopic rod 10 or 11 adjusts the opening angle of the clamping opening of the rotating plate 13. During the extension and retraction of pneumatic telescopic rod 10 or 11, the T-shaped limiting rod 12 at the bottom of pneumatic telescopic rod 11 can adapt to the sliding adjustment angle within the rotating plate 13. Activating pneumatic telescopic rod 19 supports the clamping position of the rotating clamping plate 16 after rotation, making the clamping process more stable. The limiting cylinder 8 is supported by the support frame, and the movement and transport by the support frame and displacement mechanism facilitate the movement and placement of trench pipe fittings.
[0046] It is worth noting that the circuits, electronic components, and modules involved in this utility model are all existing technologies, which can be fully implemented by those skilled in the art, and need not be elaborated upon. The content protected by this utility model does not involve any improvement to the software and methods.
[0047] It should be understood that the disclosed apparatus can be implemented in other ways, given the several embodiments provided in this application. For example, the apparatus embodiments described above are merely illustrative; the division of units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or communication connections shown or discussed may be through some interfaces; the indirect coupling or communication connections between devices or units may be telecommunications or other forms.
[0048] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Although this utility model has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of this utility model according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of this utility model. These technical solutions are also within the scope of protection of this utility model.
Claims
1. An adjustable-angle grooved pipe fitting assembly, characterized in that, Includes a limiting cylinder two (8): pneumatic telescopic rod four (11) is fixedly connected to both sides of the bottom of the limiting cylinder two (8), and pneumatic telescopic rod three (10) is fixedly connected to the center of the bottom of the limiting cylinder two (8). A rotating plate (13) is provided at the bottom of both sides of the pneumatic telescopic rod four (11). A T-shaped groove (14) is opened on the outer arc surface inside the rotating plate (13). A T-shaped limiting rod (12) is fixedly connected to the bottom of the pneumatic telescopic rod four (11). The T-shaped limiting rod (12) is restricted to sliding inside the T-shaped groove (14). A fixing plate two (24) is fixedly connected to the bottom of the pneumatic telescopic rod three (10). A through-hole is provided on both sides inside the fixing plate two (24). A positioning pin (22) is provided, which penetrates the interior of the two rotating plates (13) respectively. The positioning pin (22) is fixedly connected to the fixing plate two (24). The positioning pin (22) is slidably connected inside the rotating plate (13). The bottom of the two rotating plates (13) is rotatably connected to a rotating clamping plate (16). The two rotating plates (13) are fixedly connected to each other on opposite sides. An L-shaped fixing plate (18) is fixedly connected inside the L-shaped fixing plate (18). The extension end of the pneumatic telescopic rod five (19) faces the rotating clamping plate (16). Support frames are provided on both sides of the limiting cylinder two (8). Displacement mechanisms are provided on both sides of the support frames.
2. The adjustable-angle grooved pipe fitting assembly as described in claim 1, characterized in that, It also includes a support mechanism, which includes a frame (1), a limiting cylinder (5), a pneumatic telescopic rod (6), an L-shaped fixing rod (7), and a pneumatic telescopic rod (9). The two sides inside the limiting cylinder (8) are fixedly connected to the pneumatic telescopic rod (9). The extension end of the pneumatic telescopic rod (9) is fixedly connected to the L-shaped fixing rod (7). The other end of the L-shaped fixing rod (7) is fixedly connected to the pneumatic telescopic rod (6). The outside of the pneumatic telescopic rod (6) is fixedly connected to the limiting cylinder (5). The bottom of the limiting cylinder (5) is fixedly connected to the frame (1). The displacement mechanism is distributed on both sides of the top of the frame (1).
3. The adjustable-angle grooved pipe fitting assembly as described in claim 2, characterized in that, The two sides of the L-shaped fixing rod (7) are respectively adapted to be inserted into the interior of the limiting cylinder two (8) and the limiting cylinder one (5).
4. The adjustable-angle grooved pipe fitting assembly as described in claim 1, characterized in that, It also includes a moving mechanism, which includes a slot (2), a roller (3) and a motor (4). The slot (2) is opened on both sides of the frame (1). The roller (3) is rotatably connected inside the frame (1). The motor (4) is fixedly connected to both ends of the outer side of the frame (1). The output end of the motor (4) is fixedly connected to the roller (3).
5. The adjustable-angle grooved pipe fitting assembly as described in claim 1, characterized in that, The extension end of the pneumatic telescopic rod five (19) is fixedly connected to a fixed push plate (20), and the other side of the fixed push plate (20) is fixedly connected to a pressure-resistant steel plate (21). The outer side of the rotating clamp (16) is fixedly connected to an anti-slip layer (17), and the pressure-resistant steel plate (21) slides in contact with the anti-slip layer (17).
6. The adjustable-angle grooved pipe fitting assembly as described in claim 5, characterized in that, The pressure-resistant steel plate (21) and the anti-slip layer (17) are fitted together. The opposite surfaces of the rotating clamps (16) on both sides are flat. The rotating clamps (16) on both sides are triangular prisms. The cross section of the rotating clamps (16) is an equilateral triangle. The two opposite surfaces of the rotating clamps (16) on both sides are two symmetrical and equal surfaces of an equilateral triangular prism.
7. The adjustable-angle grooved pipe fitting assembly as described in claim 1, characterized in that, The support frame and displacement mechanism are symmetrically arranged on both sides of the limiting cylinder (8).
8. The adjustable-angle grooved pipe fitting assembly as described in claim 1, characterized in that, The top of the rotating clamp (16) is provided with a hinge (15), and the rotating clamp (16) is rotatably connected to the rotating plate (13) through the hinge (15). The T-shaped groove (14) is opened in the middle of the outer side of the rotating plate (13).
9. The adjustable-angle grooved pipe fitting assembly as described in claim 1, characterized in that, The rotating plate (13) is provided with fixing pieces (23) on both sides. The positioning pins (22) on both sides pass through the inside of the fixing pieces (23) respectively. The two ends of the fixing pieces (23) are respectively attached to the two sides of the rotating plate (13).