Multifunctional clamp for valve machining

Abstract

The utility model discloses a multifunctional clamp for valve machining, include: operation panel, the top fixed connection of operation panel has support frame, one side fixed mounting of support frame has servo motor, the output shaft rotation of servo motor penetrates support frame and fixedly connected with the rotation bucket, set up the liquid clamping unit on the rotation bucket, the liquid clamping unit includes hydraulic pressure part, and with the clamping portion of intercommunication of hydraulic pressure part, the hydraulic pressure part makes the clamping portion to the inner chamber of valve and carries out the clamping through the hydraulic pressure, sets up the support unit on operation panel. The utility model discloses through liquid clamping unit can adapt to the valve of different size, and through the 360 degrees around type clamping, to avoid the inner wall damage and provide stable clamping force, through servo motor can drive the valve and carry out the rotation, to adjust the angle of valve and facilitate the subsequent processing.

Description

Technical Field

[0001] This utility model relates to the field of valve clamping technology, and in particular to a multifunctional clamping fixture for valve processing. Background Technology

[0002] Valves are pipeline accessories used to open and close pipelines, control flow direction, and regulate and control the parameters of the transported medium. According to their functions, they can be divided into shut-off valves, check valves, regulating valves, etc. Valves are control components in fluid transport systems, and have functions such as shut-off, regulation, flow guidance, backflow prevention, pressure stabilization, flow diversion, or overflow pressure relief. Valves are used in fluid control systems and can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metals, and radioactive media.

[0003] During valve machining and grinding, clamps are needed to hold the valve. Currently, most mainstream clamps use the method of clamping the outer surface of the valve end. Since the clamp directly covers the outer surface of the valve end, this area cannot be ground, polished, or otherwise processed. Another method is to clamp the valve cavity from the inside. Although this does not affect the machining of the valve's outer surface, the valve cavity is generally cylindrical, and the inner diameter of different valve sizes is also different. This makes it difficult for block-shaped jaws or clamps to fit completely with the inner cavities of valves with different inner diameters. This not only affects the clamping stability but may also damage the valve cavity due to excessive local pressure concentration of the clamp. Therefore, a multi-functional clamp for valve machining is proposed. Utility Model Content

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the present invention.

[0005] To address the problems existing in the current multifunctional fixture for valve processing, this utility model is proposed.

[0006] Therefore, the purpose of this utility model is to provide a multifunctional fixture for valve processing, which is suitable for solving the problem that when existing fixtures clamp the valve cavity, the block-shaped claws or clamping plates are difficult to fully fit with the valve cavity of different inner diameters. This not only affects the clamping stability, but may also cause damage to the valve cavity due to excessive local pressure concentration of the fixture.

[0007] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a multi-functional fixture for valve processing, comprising:

[0008] The control panel has a support frame fixedly connected to its top, and a servo motor is fixedly installed on one side of the support frame. The output shaft of the servo motor rotates through the support frame and is fixedly connected to a rotating drum.

[0009] A liquid clamping unit is installed on a rotating drum. The liquid clamping unit includes a hydraulic unit and a clamping part connected to the hydraulic unit. The hydraulic unit uses hydraulic pressure to clamp the clamping part to clamp the inner cavity of the valve.

[0010] A support unit is installed on the operating table, the support unit being used to provide auxiliary support for the hydraulic unit;

[0011] A lifting unit is installed on the operating table. The lifting unit includes a lifting part and a guide part provided on the lifting part. The lifting part is used to lift the guide part, and the guide part is used to move the valve to the clamping part position.

[0012] In a preferred embodiment of the multifunctional fixture for valve processing described in this utility model, the hydraulic unit includes an electric push rod fixedly installed on the inner wall of a rotating drum. A hydraulic cylinder is fixedly connected to one end of the rotating drum. The output shaft of the electric push rod slides through the rotating drum and the hydraulic cylinder in sequence. The connection between the output shaft of the electric push rod and the hydraulic cylinder is sealed. A piston disc is fixedly connected to the output end of the electric push rod. A pressure sensor is embedded in the center of the piston disc. A limit plate is fixedly sleeved on the outer wall of the hydraulic cylinder.

[0013] As a preferred embodiment of the multifunctional clamp for valve processing described in this utility model, the clamping part includes a conveying pipe fixedly connected to one end of the hydraulic tank. The side wall of the conveying pipe is fixedly connected to two sets of straight pipes arranged in a ring. A piston rod is slidably and sealed in the inner cavity of each straight pipe. One end of each piston rod passes through the straight pipe and is away from the end of the conveying pipe. The liquid clamping unit also includes an adjustment component for adjusting the clamping range.

[0014] As a preferred embodiment of the multifunctional fixture for valve processing described in this utility model, the adjusting assembly includes a plurality of threaded sleeves respectively fixedly connected to the end of each piston rod, the inner cavity of each threaded sleeve is threadedly connected to an adjusting sleeve, the end of each adjusting sleeve away from the threaded sleeve is provided with a threaded hole identical to the threaded sleeve, and a clamping head is threadedly connected to the threaded hole of each adjusting sleeve.

[0015] As a preferred embodiment of the multifunctional clamp for valve processing described in this utility model, each clamping head has a hexagonal protrusion on its outer wall, and each adjusting sleeve also has a hexagonal protrusion on its outer wall.

[0016] In a preferred embodiment of the multifunctional fixture for valve processing described in this utility model, the support unit includes a support plate fixedly connected to the top of the operating table, a ring bearing fixedly connected to the top of the support plate, and the hydraulic tank and the inner ring of the bearing being interference-fitted.

[0017] As a preferred embodiment of the multifunctional fixture for valve processing described in this utility model, the lifting part includes an electric telescopic cylinder fixedly installed at the bottom of the operating table. The output shaft of the electric telescopic cylinder slides through the operating table and is fixedly connected to a fixing plate. Two balance bars are fixedly connected to the bottom of the fixing plate. Both balance bars slide through the operating table. A T-shaped groove adapted to the guide part is provided on the top of the fixing plate.

[0018] In a preferred embodiment of the multifunctional fixture for valve processing described in this utility model, the guide portion includes a T-shaped block slidably disposed in a T-shaped groove of a fixed plate, and an arc-shaped plate is fixedly connected to the top of the T-shaped block.

[0019] The beneficial effects of this utility model are: the liquid clamping unit can adapt to valves of different sizes, and through 360-degree circumferential clamping, it increases the contact surface with the valve cavity to avoid damage to the inner wall and provide stable clamping force. The servo motor can drive the valve to rotate to adjust the valve angle and facilitate subsequent processing. The lifting unit facilitates the alignment of the valve with the clamping part, thereby facilitating the clamping part to quickly clamp the valve. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0021] Figure 1 This is a schematic diagram of the overall structure of the multifunctional fixture for valve processing proposed in this utility model;

[0022] Figure 2 This is a cross-sectional schematic diagram of the internal structure of the rotating drum and hydraulic drum proposed in this utility model;

[0023] Figure 3 This is a schematic diagram showing the piston rod and adjusting assembly disassembled according to this utility model;

[0024] Figure 4 This is a schematic diagram showing the disassembly of the fixing plate and T-shaped block proposed in this utility model.

[0025] 100. Control panel; 101. Support frame; 102. Servo motor; 103. Rotary drum;

[0026] 200. Liquid clamping unit; 201. Hydraulic unit; 201a. Electric push rod; 201b. Hydraulic tank; 201c. Piston disc; 201d. Pressure sensor; 201e. Limiting disc; 202. Clamping part; 202a. Delivery pipe; 202b. Straight pipe; 202c. Piston rod; 203. Adjustment assembly; 203a. Threaded sleeve; 203b. Adjustment sleeve; 203c. Clamping head;

[0027] 300. Support unit; 301. Support plate; 302. Circular bearing;

[0028] 400, Lifting unit; 401, Lifting section; 401a, Electric telescopic cylinder; 401b, Fixing plate; 401c, Balance bar; 402, Guide section; 402a, T-block; 402b, Arc plate. Detailed Implementation

[0029] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0032] Secondly, this utility model is described in detail with reference to the schematic diagrams. When describing the embodiments of this utility model, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this utility model. In addition, actual manufacturing should include the three-dimensional spatial dimensions of length, width, and depth.

[0033] Example 1

[0034] Reference Figures 1-4The first embodiment of this utility model provides a multi-functional clamp for valve processing, which can be adapted to valves of different sizes and increases the contact surface with the valve cavity through 360-degree surround clamping, so as to avoid damage to the inner wall and provide a stable clamping force. It includes: an operating table 100, a liquid clamping unit 200, a support unit 300 and a lifting unit 400.

[0035] Among them, the top of the operating table 100 is fixedly connected to a support frame 101, and a servo motor 102 is fixedly installed on one side of the support frame 101. The output shaft of the servo motor 102 rotates through the support frame 101 and is fixedly connected to a rotating drum 103.

[0036] A liquid clamping unit 200 is provided on the rotating drum 103. The liquid clamping unit 200 includes a hydraulic part 201 and a clamping part 202 connected to the hydraulic part 201. The hydraulic part 201 uses hydraulic pressure to cause the clamping part 202 to clamp the inner cavity of the valve.

[0037] A support unit 300 is provided on the control panel 100, which is used to provide auxiliary support for the hydraulic unit 201;

[0038] A lifting unit 400 is provided on the control panel 100. The lifting unit 400 includes a lifting part 401 and a guide part 402 provided on the lifting part 401. The lifting part 401 is used to lift the guide part 402, and the guide part 402 is used to move the valve to the clamping part 202 position.

[0039] The valve is placed on the guide portion 402 and raised together with the guide portion 402 by the lifting portion 401 to a height suitable for the clamping portion 202. Then, the valve is moved by the guide portion 402 so that the clamping portion 202 is located in the inner cavity of one end of the valve. Subsequently, the lifting portion 401 drives the guide portion 402 to descend and reset. Then, the hydraulic portion 201 expands the clamping portion 202 inside the valve through hydraulic action, clamping the inner cavity of the valve in a 360-degree circumferential clamping manner. This avoids damage to the inner wall and provides stable clamping. The servo motor 102 output shaft passes through a through hole on the support frame 101 that is adapted to it and has an internal bearing. The servo motor 102 can drive the rotating drum 103 to rotate, thereby adjusting the angle of the valve so as to process different positions of the valve. The support unit 300 is used to share the support load of the servo motor 102 and make the rotation of the servo motor 102 more stable. After the processing is completed, the hydraulic unit 201 releases the hydraulic action on the clamping part 202, so that the clamping part 202 is no longer clamped, and then the valve can be removed.

[0040] Example 2

[0041] Reference Figures 1-3This is the second embodiment of the present invention. Unlike the previous embodiment, the hydraulic unit 201 includes an electric push rod 201a fixedly installed on the inner wall of the rotating drum 103. One end of the rotating drum 103 is fixedly connected to a hydraulic tank 201b. The output shaft of the electric push rod 201a slides through the rotating drum 103 and the hydraulic tank 201b in sequence. The connection between the output shaft of the electric push rod 201a and the hydraulic tank 201b is sealed. The output end of the electric push rod 201a is fixedly connected to a piston disc 201c. A pressure sensor 201d is embedded in the center of the piston disc 201c. A limit disc 201e is fixedly sleeved on the outer wall of the hydraulic tank 201b.

[0042] The hydraulic tank 201b is filled with hydraulic oil. An electric push rod 201a is used to push and pull the piston disc 201c. The piston disc 201c and the inner wall of the hydraulic tank 201b are sealed by a sealing ring. When the piston disc 201c moves towards the limit disc 201e, the hydraulic oil in the hydraulic tank 201b is squeezed to the clamping part 202, which clamps the valve. The pressure sensor 201d is used to monitor the internal pressure of the hydraulic tank 201b. The pressure sensor 201d can sense pressure signals and convert them according to a certain pattern. The device or apparatus that outputs a usable electrical signal, the pressure sensor 201d can be used in conjunction with an external data receiving device to determine the internal pressure of the hydraulic tank 201b, so as to avoid the hydraulic pressure supplied to the clamping part 202 being too large or too small, thereby causing the valve to be damaged or unstable. The limit plate 201e is used to limit one end of the valve, so that the valve stays on the clamping part 202. When the piston plate 201c is pulled away from the limit plate 201e by the electric push rod 201a, the hydraulic tank 201b no longer provides hydraulic force to the clamping part 202.

[0043] The clamping unit 202 includes a delivery pipe 202a fixedly connected to one end of the hydraulic tank 201b. The side wall of the delivery pipe 202a is fixedly connected to two sets of straight pipes 202b arranged in a ring. Each straight pipe 202b has a piston rod 202c slidably sealed in its inner cavity. One end of each piston rod 202c passes through the end of the straight pipe 202b away from the delivery pipe 202a. The liquid clamping unit 200 also includes an adjustment component 203 for adjusting the clamping range.

[0044] Hydraulic oil is filled in the delivery pipe 202a. When the electric push rod 201a pushes the piston disc 201c, the hydraulic oil in the hydraulic tank 201b is delivered to the delivery pipe 202a. The hydraulic oil in the delivery pipe 202a squeezes the piston rod 202c in each straight pipe 202b, forcing the piston rod 202c to slide inside the straight pipe 202b and move away from it. The multiple straight pipes 202b in each group are distributed in a ring at equal intervals. The intervals between the straight pipes 202b in the two groups are alternately complementary, so that the piston rod 202c forms a 360-degree ring. This, together with the adjusting component 203, stably clamps the inner cavity of the valve. When the electric push rod 201a pulls the piston disc 201c away from the limit disc 201e, the hydraulic tank 201b stops delivering hydraulic oil to the delivery pipe 202a. Under the action of negative pressure, the piston rod 202c automatically slides back into the straight pipe 202b.

[0045] Specifically, the adjustment assembly 203 includes multiple threaded sleeves 203a that are fixedly connected to the end of each piston rod 202c. Each threaded sleeve 203a has an adjustment sleeve 203b threadedly connected to its inner cavity. Each adjustment sleeve 203b has a threaded hole at its end away from the threaded sleeve 203a, which is the same as that of the threaded sleeve 203a. Each adjustment sleeve 203b has a clamping head 203c threadedly connected to its threaded hole.

[0046] When the piston rod 202c expands with hydraulic pressure, the multiple clamping heads 203c, through the annular telescopic design formed by the moving piston rod 202c, contact the inner wall of the valve. The multiple annularly distributed clamping heads 203c increase the contact area between the clamping heads 203c and the valve cavity, providing a stable clamping force. The clamping heads 203c can be directly threaded into the threaded sleeve 203a to reduce the annular telescopic range formed by the multiple clamping heads 203c and adapt to small-sized valves. The two adjusting sleeves 203b can be rotated and connected through threaded holes. By adjusting the sleeves 203b, the length of the clamping heads 203c can be increased, thereby expanding the annular telescopic range formed by the multiple clamping heads 203c to adapt to large-sized valves.

[0047] It should be noted that each clamping head 203c has a hexagonal protrusion on its outer wall, and each adjusting sleeve 203b also has a hexagonal protrusion on its outer wall.

[0048] The hexagonal protrusions of the clamping head 203c and the adjusting sleeve 203b can be adapted to tools such as wrenches to rotate the clamping head 203c and the adjusting sleeve 203b, thereby facilitating the assembly and disassembly of the clamping head 203c and the adjusting sleeve 203b.

[0049] Example 3

[0050] Reference Figure 1 and Figure 4 This is the third embodiment of the present invention. Unlike the previous embodiment, the support unit 300 includes a support plate 301 fixedly connected to the top of the operating table 100. A ring bearing 302 is fixedly connected to the top of the support plate 301, and the hydraulic tank 201b is interference-fitted with the inner ring of the bearing.

[0051] The hydraulic tank 201b can rotate in the inner ring of the ring bearing 302. The inner ring of the ring bearing 302 provides radial support for the hydraulic tank 201b, which counteracts the centrifugal force and part of the gravitational force generated by the rotation of the rotating tank 103, thereby reducing the load on the servo motor 102.

[0052] Example 4

[0053] Reference Figure 1 and Figure 4 This is the fourth embodiment of the present invention. Unlike the previous embodiment, the lifting part 401 includes an electric telescopic cylinder 401a fixedly installed at the bottom of the operating table 100. The output shaft of the electric telescopic cylinder 401a slides through the operating table 100 and is fixedly connected to a fixing plate 401b. Two balance bars 401c are fixedly connected to the bottom of the fixing plate 401b. Both balance bars 401c slide through the operating table 100. The top of the fixing plate 401b is provided with a T-shaped groove adapted to the guide part 402.

[0054] The output shaft of the electric telescopic cylinder 401a is used to drive the fixed plate 401b to rise and fall, thereby raising the guide part 402. The two balance bars 401c can rise and fall together with the fixed plate 401b. When the guide part 402 slides on the fixed plate 401b, the two balance bars 401c are used to keep the fixed plate 401b balanced, so that when the guide part 402 slides to the end of the fixed plate 401b, the end of the fixed plate 401b is prevented from shifting downward due to excessive load.

[0055] The guide part 402 includes a T-shaped block 402a that is slidably disposed in a T-shaped groove in the fixed plate 401b, and an arc plate 402b is fixedly connected to the top of the T-shaped block 402a.

[0056] T-shaped block 402a is slidably disposed in the T-shaped groove of fixed plate 401b. Arc plate 402b can be slid by T-shaped block 402a. Arc plate 402b is arc-shaped so that valve can be moved to the center of arc plate 402b. When the valve is on arc plate 402b, the valve is lifted by lifting part 401. By moving arc plate 402b, the heavier valve can be quickly aligned with clamping part 202 so that clamping part 202 can clamp it.

[0057] During use, firstly, the number of adjusting sleeves 203b is increased or decreased on the threaded sleeve 203a according to the size of the valve to adapt to valves of different sizes. Then, the valve is placed on the arc plate 402b. Next, the electric telescopic cylinder 401a drives the fixed plate 401b to rise, so that the center line of the valve end is at the same height as the delivery pipe 202a. Then, the arc plate 402b is slid so that the inner cavity of one end of the valve is fitted onto the clamping part 202. At this time, the electric push rod 201a pushes the piston disc 201c, so that the hydraulic oil in the hydraulic tank 201b is delivered to the delivery pipe 202a. The hydraulic oil in the delivery pipe 202a squeezes the piston rod 202c in each straight pipe 202b, so that the piston rod 202c pushes the clamping head 203c to contact the valve inner cavity. The multiple ring-shaped clamping heads 203c increase the contact surface between the clamping head 203c and the valve inner cavity and provide a stable clamping force.

[0058] After clamping, the electric telescopic cylinder 401a drives the fixed plate 401b to descend, allowing the valve to be processed. The servo motor 102 drives the rotating drum 103 to rotate, adjusting the valve angle for processing. After processing, the electric telescopic cylinder 401a drives the fixed plate 401b to rise, supporting the valve with the arc plate 402b. Then, the electric push rod 201a pulls the piston plate 201c away from the limit plate 201e, causing the piston rod 202c to automatically slide back into the straight tube 202b. When the clamping head 203c no longer clamps the valve, the arc plate 402b can slide and the valve can be removed.

[0059] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A multi-functional fixture for valve processing, characterized in that, include: An operating table (100) is fixedly connected to a support frame (101) on its top. A servo motor (102) is fixedly installed on one side of the support frame (101). The output shaft of the servo motor (102) rotates through the support frame (101) and is fixedly connected to a rotating drum (103). A liquid clamping unit (200) is provided on the rotating drum (103). The liquid clamping unit (200) includes a hydraulic part (201) and a clamping part (202) connected to the hydraulic part (201). The hydraulic part (201) uses hydraulic pressure to cause the clamping part (202) to clamp the inner cavity of the valve. A support unit (300) is provided on the control panel (100), the support unit (300) being used to provide auxiliary support for the hydraulic unit (201); A lifting unit (400) is provided on the operating table (100). The lifting unit (400) includes a lifting part (401) and a guide part (402) provided on the lifting part (401). The lifting part (401) is used to lift the guide part (402), and the guide part (402) is used to move the valve to the clamping part (202) position. The hydraulic unit (201) includes an electric push rod (201a) fixedly installed on the inner wall of the rotating drum (103). One end of the rotating drum (103) is fixedly connected to a hydraulic tank (201b). The output shaft of the electric push rod (201a) slides through the rotating drum (103) and the hydraulic tank (201b) in sequence. The connection between the output shaft of the electric push rod (201a) and the hydraulic tank (201b) is sealed. The output end of the electric push rod (201a) is fixedly connected to a piston disc (201c). A pressure sensor (201d) is embedded in the center of the piston disc (201c). A limit disc (201e) is fixedly sleeved on the outer wall of the hydraulic tank (201b).

2. The multi-functional fixture for valve machining according to claim 1, characterized in that: The clamping part (202) includes a delivery pipe (202a) fixedly connected to one end of the hydraulic tank (201b). The side wall of the delivery pipe (202a) is fixedly connected to two sets of straight pipes (202b) arranged in a ring. Each straight pipe (202b) has a piston rod (202c) slidably and sealed in its inner cavity. One end of each piston rod (202c) passes through the straight pipe (202b) away from the end of the delivery pipe (202a). The liquid clamping unit (200) also includes an adjustment component (203) for adjusting the clamping range.

3. The multi-functional fixture for valve machining according to claim 2, characterized in that: The adjustment assembly (203) includes a plurality of threaded sleeves (203a) respectively fixedly connected to the end of each piston rod (202c). Each threaded sleeve (203a) has an adjustment sleeve (203b) threadedly connected to its inner cavity. Each adjustment sleeve (203b) has a threaded hole with the same thread as the threaded sleeve (203a) at one end away from the threaded sleeve (203a). Each adjustment sleeve (203b) has a clamping head (203c) threadedly connected to its threaded hole.

4. A multi-functional fixture for valve processing according to claim 3, characterized in that: Each of the clamping heads (203c) has a hexagonal protrusion on its outer wall, and each of the adjusting sleeves (203b) also has a hexagonal protrusion on its outer wall.

5. The multi-functional fixture for valve machining according to claim 4, characterized in that: The support unit (300) includes a support plate (301) fixedly connected to the top of the operating table (100), and a ring bearing (302) is fixedly connected to the top of the support plate (301). The hydraulic tank (201b) is interference-fitted with the inner ring of the bearing.

6. A multi-functional fixture for valve processing according to claim 5, characterized in that: The lifting part (401) includes an electric telescopic cylinder (401a) fixedly installed at the bottom of the operating table (100). The output shaft of the electric telescopic cylinder (401a) slides through the operating table (100) and is fixedly connected to a fixing plate (401b). Two balance bars (401c) are fixedly connected to the bottom of the fixing plate (401b). Both balance bars (401c) slide through the operating table (100). The top of the fixing plate (401b) is provided with a T-shaped groove adapted to the guide part (402).

7. The multi-functional fixture for valve machining according to claim 6, characterized in that: The guide part (402) includes a T-shaped block (402a) slidably disposed in a T-shaped groove of a fixed plate (401b), and an arc plate (402b) is fixedly connected to the top of the T-shaped block (402a).

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