Multilayer rectifying tower
The easily detachable insulation board connection device solves the problem of easy damage to the insulation board in the multi-layer distillation column in cold environments, enabling quick replacement and efficient insulation, and improving the practicality of the equipment.
Patent Information
- Application Number
- CN202422618946.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-29
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2034-10-29
AI Technical Summary
When existing multi-layer distillation columns are used in cold and harsh environments, the insulation cotton or insulation board is easily damaged, and maintenance and replacement are time-consuming and labor-intensive, affecting the practicality of the equipment.
It adopts an easy-to-disassemble device, including a first insulation board, a second insulation board, a screw hole block and a limiting device. The insulation board can be quickly disassembled and assembled through the connection of the threaded rod and the screw hole block, which facilitates replacement and maintenance.
It simplifies the process of replacing insulation panels, improves the insulation efficiency and practicality of the equipment in cold environments, and reduces maintenance difficulty.
Smart Images
Figure CN223570047U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the technical field of multilayer rectifying tower, especially to a multilayer rectifying tower. BACKGROUND
[0002] The multilayer rectifying tower is an important chemical process equipment, mainly used for separating and purifying various components in the mixture.
[0003] The multilayer rectifying tower body is usually directly set in the external environment for use, if the external environment of the multilayer rectifying tower body is cold and harsh, the efficiency of rectification inside the multilayer rectifying tower body will be affected, in reality, the multilayer rectifying tower body is usually treated by applying thermal insulation paint or fixedly installing thermal insulation cotton and thermal insulation board on the outside of the multilayer rectifying tower body, if the fixedly installed thermal insulation cotton or thermal insulation board is collided or scratched by external force during use, damage may occur, and when maintenance and replacement are carried out, the fixedly installed thermal insulation board and thermal insulation cotton will cause the maintenance personnel to spend time and effort on the disassembling and assembling steps, thereby reducing the practicability of the multilayer rectifying tower body. UTILITY MODEL CONTENT
[0004] The utility model aims at solving the shortcomings in the prior art and provides a multilayer rectifying tower.
[0005] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a multilayer rectifying tower, comprising a multilayer rectifying tower body, a plurality of water inlet pipes are arranged on the outer surface of the multilayer rectifying tower body, a plurality of water outlet pipes are arranged on the outer surface of the multilayer rectifying tower body, a conveying pipe is arranged on one side of the water inlet pipe and the water outlet pipe, a convenient dismounting device is arranged on the outer surface of the multilayer rectifying tower body, a limiting device is arranged between the water inlet pipe, the water outlet pipe and the conveying pipe, the convenient dismounting device comprises a first thermal insulation board, a second thermal insulation board and a plurality of threaded hole blocks, a plurality of round hole blocks are fixedly connected to the outer surface of the multilayer rectifying tower body in a symmetrical manner, thermal insulation cotton is arranged on the inner walls of the first thermal insulation board and the second thermal insulation board, the first thermal insulation board, the second thermal insulation board and the thermal insulation cotton are all sleeved on the outer surface of the multilayer rectifying tower body, first grooves are formed in the inner walls of both ends of the first thermal insulation board, threaded rods are fixedly connected to the inner walls of the first grooves, a plurality of second grooves are formed in the inner walls of both ends of the second thermal insulation board, round holes are formed in the inner walls of the second grooves, the threaded rods are inserted into the inner walls of the round hole blocks and the round holes, and the threaded hole blocks are screwingly sleeved on the outer surface of the threaded rods.
[0006] The effect achieved by the above-mentioned components is that: by arranging the detachable device, when the multi-stage rectifying tower body is installed and used in a relatively cold and harsh environment, the second heat preservation plate and the heat preservation cotton can be manually arranged on one side of the outer surface of the multi-stage rectifying tower body, the inner walls at both ends of the second heat preservation plate and the second grooves are clamped on the outer surface of one end of the water inlet pipe, the water outlet pipe and the round hole block respectively, then the first heat preservation plate and the heat preservation cotton are arranged on the opposite side of the second heat preservation plate of the outer surface of the multi-stage rectifying tower body, the other end of the multi-stage rectifying tower body is wrapped, the plurality of threaded rods are inserted into the plurality of round hole blocks and the circular holes respectively, the first grooves and the inner walls at both ends of the first heat preservation plate are sleeved on the other outer surfaces of the water inlet pipe, the water outlet pipe and the round hole block, and finally the plurality of threaded blocks are screwed on the plurality of threaded rods, and the threaded blocks are abutted on one side of the second heat preservation plate on the side of being screwed, so that the first heat preservation plate and the second heat preservation plate are squeezed and tightened, and the heat preservation cotton is tightly attached to the outer surface of the multi-stage rectifying tower body to perform heat preservation treatment, thereby improving the efficiency of rectification. Similarly, when the heat preservation plate is damaged by external force collision during use, the threaded blocks can be unscrewed from the threaded rods, and the first heat preservation plate, the second heat preservation plate and the heat preservation cotton can be detached from the multi-stage rectifying tower body, so that the first heat preservation plate, the second heat preservation plate and the heat preservation cotton can be replaced and maintained, which is simple and convenient to operate, and improves the practicability of the multi-stage rectifying tower body.
[0007] Preferably, the outer surface of the threaded block is fixedly connected with a plurality of twisting blocks, and the plurality of twisting blocks are arranged at equal distances.
[0008] The effect achieved by the above-mentioned components is that: by arranging the twisting blocks, the contact area of the outer surface of the threaded block can be increased, and the threaded block can be manually held and twisted.
[0009] Preferably, one side of the threaded block is fixedly connected with an anti-skid block, and the anti-skid block is made of rubber.
[0010] The effect achieved by the above-mentioned components is that: by arranging the anti-skid block, the contact friction force of one side of the threaded block can be increased, so that the threaded block is more firmly abutted on the second heat preservation plate and is not easy to rotate and loosen.
[0011] Preferably, the inner walls of the first heat preservation plate and the second heat preservation plate are fixedly connected with tin foil paper, and one side of the tin foil paper is fixedly connected with one side of the heat preservation cotton.
[0012] The effect achieved by the above-mentioned components is that: by arranging the tin foil paper, the heat preservation effect of the heat preservation cotton can be stronger, so that the temperature of the outer surface of the multi-stage rectifying tower body is not easy to be lost, and the heat preservation effect is improved.
[0013] Preferably, the limiting device comprises two clamping hole limiting blocks, the outer surface of one end of the water inlet pipe and the water outlet pipe is fixedly connected with a U-shaped block in a symmetrical manner, one end of the clamping hole limiting block is rotatably connected with the inner wall of the U-shaped block, one side of the conveying pipe is fixedly connected with a circular hole frame in a symmetrical manner, the inner wall of the circular hole frame is slidably connected with a circular rod, one end of the circular rod is fixedly connected with a clamping block, the outer surface of the circular rod is sleeved with a spring, the two ends of the spring are fixedly connected with the circular hole frame and one side of the clamping block respectively, one end of the clamping block is inserted into the inner wall of the clamping hole limiting block, and one end of the clamping hole limiting block is inserted into the inner wall of the circular hole frame.
[0014] The effect achieved by the above component is that: after the limiting device is arranged and the conveying pipe is installed on the water inlet pipe and the water outlet pipe, the clamping hole limiting block can be rotated to a certain angle in the inner wall of the U-shaped block, one end of the inner wall is clamped on one side of one end of the conveying pipe, one end of the clamping hole limiting block is clamped into the inner wall of the circular hole frame, the clamping block is extruded, the clamping block slides to one side in the inner wall of the circular hole frame by means of the circular rod, the spring is contracted, then the clamping hole limiting block is extruded to a certain position, when one end of the clamping hole limiting block is completely inserted into the inner wall of the circular hole frame, the clamping block is inserted into the inner wall of the clamping hole limiting block under the reset action of the spring, the conveying pipe is limited on the water inlet pipe, the clamping block fixes the clamping hole limiting block, the connection is more firm and stable, and the clamping block is not easy to loosen and fall off.
[0015] Preferably, the cross section of the clamping block is trapezoidal, and the size of one end of the clamping block close to the circular rod is larger than the size of the other end.
[0016] The effect achieved by the above component is that: by arranging the clamping block in a trapezoidal shape, the clamping hole limiting block can be conveniently rotated to a certain angle, one end of the clamping hole limiting block abuts on one side of the inclined surface of the trapezoidal block, the clamping block is conveniently extruded to be contracted on the circular hole block by means of the circular rod, then the clamping block is quickly clamped into the inner wall of the clamping hole limiting block under the reset action of the spring, and the operation is convenient.
[0017] Preferably, one end of the circular rod is fixedly connected with a pulling block, and the longitudinal section of the pulling block is circular.
[0018] The effect achieved by the above component is that: by arranging the pulling block, the contact area of one end of the circular rod can be increased, and the pulling block is convenient to hook and pull manually.
[0019] Preferably, the outer surface of one end of the clamping hole limiting block is fixedly connected with a bearing in a symmetrical manner, and the outer ring of the bearing is fixedly connected with the inner wall of the U-shaped block.
[0020] The effect achieved by the above component is that: by arranging the bearing, the rotating wear between the clamping hole limiting block and the U-shaped block can be reduced, and the service life of the two is improved.
[0021] Compared with the prior art, the utility model has the advantages and positive effects that:
[0022] The utility model discloses a convenient to detach device is set up, in the use process, if the heat preservation board is hit and scraped by external force, only needs to spiral down from the threaded rod with the screw hole block, can first heat preservation board and second heat preservation board and heat preservation cotton are detached from multistage rectifying tower main body, is convenient for its replacement maintenance treatment, and the operation step is simple and convenient, and the practicability of multistage rectifying tower main body is improved. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 It is the three-dimensional structure schematic diagram of the utility model;
[0024] Figure 2 It is the three-dimensional structure schematic diagram of the utility model multistage rectifying tower main body place;
[0025] Figure 3 It is Figure 2 The middle part structure three-dimensional schematic diagram;
[0026] Figure 4 It is the three-dimensional structure schematic diagram of the utility model first heat preservation board place;
[0027] Figure 5 It is Figure 4 The middle part structure three-dimensional schematic diagram;
[0028] Figure 6 It is Figure 5 The three-dimensional structure schematic diagram of the utility model A place is enlarged.
[0029] Legend explanation: 1, multistage rectifying tower main body;2, convenient to detach device;3, limiting device;4, inlet pipe;5, outlet pipe;6, delivery pipe;21, round hole block;22, first heat preservation board;23, second heat preservation board;24, heat preservation cotton;25, first recess;26, threaded rod;27, screw hole block;28, second recess;29, round hole;210, twist block;211, antiskid block;212, tin foil paper;31, U-shaped block;32, clamping hole limiting block;33, round hole frame;34, round rod;35, clamping block;36, spring;37, pull block;38, bearing. DETAILED DESCRIPTION
[0030] Example 1, such as Figures 1-6The utility model provides a kind of multi-layer rectifying tower, including multi-layer rectifying tower main body 1, the outer surface of multi-layer rectifying tower main body 1 is provided with several water inlets 4, the outer surface of multi-layer rectifying tower main body 1 is provided with several water outlets 5, the side of water inlet 4 and water outlet 5 is provided with conveying pipe 6, the outer surface of multi-layer rectifying tower main body 1 is provided with convenient dismounting device 2, limiting device 3 is arranged between water inlet 4 and conveying pipe 6 and water outlet 5, convenient dismounting device 2 includes first heat preservation plate 22, second heat preservation plate 23 and several screw hole blocks 27, the outer surface of multi-layer rectifying tower main body 1 is fixedly connected with several round hole blocks 21 symmetrically, the inner wall of first heat preservation plate 22 and second heat preservation plate 23 is provided with heat insulation cotton 24, first heat preservation plate 22, second heat preservation plate 23 and heat insulation cotton 24 are all set on the outer surface of multi-layer rectifying tower main body 1, the inner wall of first heat preservation plate 22 is provided with first recess 25 in both ends, first recess 25 is fixedly connected with threaded rod 26 in inner wall, the inner wall of second heat preservation plate 23 is provided with several second recesses 28 in both ends, second recess 28 is provided with circular hole 29 in inner wall, threaded rod 26 is inserted in the inner wall of round hole block 21 and circular hole 29, screw hole block 27 is spirally set on the outer surface of threaded rod 26.In when multi-layer rectifying tower main body 1 is installed in the relatively cold and harsh environment outside and is used, second heat preservation plate 23 and heat insulation cotton 24 can be manually set on the outer surface of multi-layer rectifying tower main body 1, so that the inner wall of both ends and several second recesses 28 are respectively clamped on the outer surface of one end of water inlet 4 and water outlet 5 and round hole block 21, then first heat preservation plate 22 and heat insulation cotton 24 are set on the opposite side of second heat preservation plate 23 of the outer surface of multi-layer rectifying tower main body 1, the other end of multi-layer rectifying tower main body 1 is wrapped, while several threaded rods 26 are respectively inserted in several round hole blocks 21 and circular holes 29, and the inner wall of both ends of first recess 25 and first heat preservation plate 22 is set on the other outer surface of water inlet 4 and water outlet 5 and round hole block 21, finally several screw hole blocks 27 are spirally screwed on several threaded rods 26, and are tightly abutted on one side of second heat preservation plate 23 on one side, first heat preservation plate 22 and second heat preservation plate 23 are extruded and tightened, heat insulation cotton 24 is tightly attached to the outer surface of multi-layer rectifying tower main body 1 to carry out heat preservation treatment, improve the efficiency of rectification, and the same reason, in the use process, if heat preservation plate is collided and scraped by external force, first heat preservation plate 22 and second heat preservation plate 23 and heat insulation cotton 24 can be dismounted from multi-layer rectifying tower main body 1 by spirally unscrewing screw hole block 27 from threaded rod 26, so as to facilitate replacement and maintenance treatment, which is relatively simple and convenient in operation steps, convenient to operate, and improve the practicability of multi-layer rectifying tower main body 1.
[0031] Refer to Figures 4-6As shown, the embodiment discloses that the outer surface of the screw hole block 27 is fixedly connected with a plurality of screw blocks 210, and the plurality of screw blocks 210 are arranged at equal distances. By arranging the screw blocks 210, the contact area of the outer surface of the screw hole block 27 can be increased, and the screw hole block 27 is convenient to hold and twist manually.
[0032] Referring to Figures 4-6 As shown, the embodiment discloses that one side of the screw hole block 27 is fixedly connected with an anti-skid block 211, and the anti-skid block 211 is made of rubber. By arranging the anti-skid block 211, the contact friction of one side of the screw hole block 27 can be increased, so that the one side is more firm when abutting against the second heat preservation plate 23 and is not easy to rotate and loosen. The inner walls of the first heat preservation plate 22 and the second heat preservation plate 23 are fixedly connected with tin foil paper 212, and one side of the tin foil paper 212 is fixedly connected with one side of the heat preservation cotton 24. By arranging the tin foil paper 212, the heat preservation effect of the heat preservation cotton 24 can be stronger, so that the temperature of the outer surface of the multi-layer rectifying tower main body 1 is not easy to lose, and the heat preservation effect is improved.
[0033] Referring to Figure 2 and Figure 3 As shown, the embodiment discloses that the limiting device 3 includes two clamping hole limiting blocks 32, the outer surfaces of one end of the water inlet pipe 4 and the water outlet pipe 5 are fixedly connected with U-shaped blocks 31 in a symmetrical manner, one end of the clamping hole limiting block 32 is rotatably connected with the inner wall of the U-shaped block 31, one side of the conveying pipe 6 is fixedly connected with a circular hole frame 33 in a symmetrical manner, the inner wall of the circular hole frame 33 is slidably connected with a circular rod 34, one end of the circular rod 34 is fixedly connected with a clamping block 35, the outer surface of the circular rod 34 is sleeved with a spring 36, the two ends of the spring 36 are fixedly connected with one side of the circular hole frame 33 and the clamping block 35 respectively, one end of the clamping block 35 is inserted into the inner wall of the clamping hole limiting block 32, and one end of the clamping hole limiting block 32 is inserted into the inner wall of the circular hole frame 33. After the conveying pipe 6 is installed on the water inlet pipe 4 and the water outlet pipe 5, the clamping hole limiting block 32 can be rotated to a certain angle in the inner wall of the U-shaped block 31, one end of the inner wall is clamped on one side of one end of the conveying pipe 6, one end of the clamping hole limiting block 32 is clamped into the inner wall of the circular hole frame 33, the clamping block 35 is extruded, the clamping block 35 slides to one side in the inner wall of the circular hole frame 33 by means of the circular rod 34, the spring 36 is contracted, then the clamping hole limiting block 32 is extruded to a certain position, one end of the clamping hole limiting block 32 is completely inserted into the inner wall of the circular hole frame 33, under the reset action of the spring 36, one end of the clamping block 35 is inserted into the inner wall of the clamping hole limiting block 32, the conveying pipe 6 is limited on the water inlet pipe 4, the clamping block 35 fixes the clamping hole limiting block 32, so that the connection is more firm and stable, and is not easy to loosen and fall off.
[0034] Referring to Figure 2 and Figure 3As shown, the embodiment discloses that the cross section of the clamping block 35 is trapezoidal, and the size of the clamping block 35 near one end of the circular rod 34 is larger than the size of the other end. By setting the clamping block 35 to be trapezoidal, the one end of the clamping hole limiting block 32 can be abutted on one side of the inclined surface of the trapezoidal block after being rotated to a certain angle, facilitating extrusion and shrinkage of the clamping hole limiting block 32 on the circular hole block 21 through the circular rod 34, and then quickly clamping into the inner wall of the clamping hole limiting block 32 under the resetting action of the spring 36, facilitating operation. One end of the circular rod 34 is fixedly connected with a pulling block 37, and the longitudinal section of the pulling block 37 is circular. By setting the pulling block 37, the contact area of one end of the circular rod 34 can be increased, facilitating manual hooking and pulling. The outer surfaces of both sides of one end of the clamping hole limiting block 32 are fixedly connected with bearings 38, and the outer rings of the bearings 38 are fixedly connected with the inner wall of the U-shaped block 31. By setting the bearings 38, the rotating wear between the clamping hole limiting block 32 and the U-shaped block 31 can be reduced, and the service life of the two can be improved.
[0035] Working principle, when the multi-layer rectifying tower body 1 is installed in a relatively cold and harsh environment for use, the second heat preservation plate 23 and the heat preservation cotton 24 can be manually sleeved on one side of the outer surface of the multi-layer rectifying tower body 1, so that the inner walls of both ends and the second grooves 28 are clamped on the water inlet pipe 4 and the water outlet pipe 5 and one end of the circular hole block 21, and then the first heat preservation plate 22 and the heat preservation cotton 24 are sleeved on the opposite side of the second heat preservation plate 23 of the outer surface of the multi-layer rectifying tower body 1, so that the other end of the multi-layer rectifying tower body 1 is wrapped, and the threaded rods 26 are inserted into the circular hole blocks 21 and the circular holes 29, and the first grooves 25 and the inner walls of both ends of the first heat preservation plate 22 are sleeved on the other outer surfaces of the water inlet pipe 4, the water outlet pipe 5 and the circular hole block 21, and finally the screw blocks 27 are screwed on the threaded rods 26, and the screwed side is abutted on one side of the second heat preservation plate 23, so that the first heat preservation plate 22 and the second heat preservation plate 23 are extruded and tightened, and the heat preservation cotton 24 is tightly attached to the outer surface of the multi-layer rectifying tower body 1 for heat preservation treatment, improving the efficiency of rectification. Similarly, if the heat preservation plate is damaged by external force collision during use, the first heat preservation plate 22 and the second heat preservation plate 23 and the heat preservation cotton 24 can be disassembled from the multi-layer rectifying tower body 1 by screwing the screw blocks 27 from the threaded rods 26, so that they can be replaced and maintained, which is simple and convenient to operate, and improves the practicality of the multi-layer rectifying tower body 1.
[0036] After the delivery pipe 6 is installed on the water inlet pipe 4 and the water outlet pipe 5, the clamping hole limiting block 32 can be rotated to a certain angle in the inner wall of the U-shaped block 31, one end of the inner wall is clamped on one side of one end of the delivery pipe 6, and one end of the clamping hole limiting block 32 is clamped into the inner wall of the round hole frame 33, the clamping block 35 is extruded, and the clamping block 35 slides to one side in the inner wall of the round hole frame 33 by means of the round rod 34, and the spring 36 is retracted. Then, after extrusion to a certain position, when one end of the clamping hole limiting block 32 is completely inserted into the inner wall of the round hole frame 33, under the restoring action of the spring 36, one end of the clamping block 35 is inserted into the inner wall of the clamping hole limiting block 32, and the delivery pipe 6 is limited on the water inlet pipe 4. After the clamping block 35 fixes the clamping hole limiting block 32, the connection is more firm and stable, and is not easy to loosen and fall off.
Claims
1. A multi-stage rectification column comprising a multi-stage rectification column body (1), characterized by: The outer surface of the multi-layer rectifying tower body (1) is provided with a plurality of water inlet pipes (4), the outer surface of the multi-layer rectifying tower body (1) is provided with a plurality of water outlet pipes (5), one side of the water inlet pipe (4) and the water outlet pipe (5) is provided with a conveying pipe (6), the outer surface of the multi-layer rectifying tower body (1) is provided with a convenient dismounting device (2), the water inlet pipe (4) and the water outlet pipe (5) and the conveying pipe (6) are provided with a limiting device (3), the convenient dismounting device (2) comprises a first heat preservation plate (22), a second heat preservation plate (23) and a plurality of threaded hole blocks (27), the outer surface of the multi-layer rectifying tower body (1) is fixedly connected with a plurality of round hole blocks (21) in a symmetrical manner, the inner walls of the first heat preservation plate (22) and the second heat preservation plate (23) are provided with heat preservation cotton (24), the first heat preservation plate (22), the second heat preservation plate (23) and the heat preservation cotton (24) are all sleeved on the outer surface of the multi-layer rectifying tower body (1), the inner walls of the first heat preservation plate (22) are provided with first grooves (25) at both ends, the inner walls of the first grooves (25) are fixedly connected with threaded rods (26), the inner walls of the second heat preservation plate (23) are provided with a plurality of second grooves (28) at both ends, the inner walls of the second grooves (28) are provided with round holes (29), the threaded rods (26) are inserted into the inner walls of the round hole blocks (21) and the round holes (29), and the threaded hole blocks (27) are screwedly sleeved on the outer surfaces of the threaded rods (26).
2. A multi-stage rectification column according to claim 1, characterized in that: The outer surfaces of the threaded hole blocks (27) are fixedly connected with a plurality of twisting blocks (210), and the plurality of twisting blocks (210) are arranged at equal distances.
3. A multi-stage rectification column according to claim 1, characterized in that: One side of the threaded hole block (27) is fixedly connected with an anti-skid block (211), and the anti-skid block (211) is made of rubber.
4. A multi-stage rectification column according to claim 1, characterized in that: The inner walls of the first heat preservation plate (22) and the second heat preservation plate (23) are fixedly connected with tin foil paper (212), and one side of the tin foil paper (212) is fixedly connected with one side of the heat preservation cotton (24).
5. A multi-stage rectification column according to claim 1, characterized in that: The limiting device (3) comprises two clamping hole limiting blocks (32), one end of the water inlet pipe (4) and the water outlet pipe (5) is fixedly connected with a U-shaped block (31) in a symmetrical manner, one end of the clamping hole limiting block (32) is rotatably connected with the inner wall of the U-shaped block (31), one side of the conveying pipe (6) is fixedly connected with a round hole frame (33) in a symmetrical manner, the inner wall of the round hole frame (33) is slidably connected with a round rod (34), one end of the round rod (34) is fixedly connected with a clamping block (35), the outer surface of the round rod (34) is sleeved with a spring (36), the two ends of the spring (36) are fixedly connected with one side of the round hole frame (33) and the clamping block (35) respectively, one end of the clamping block (35) is inserted into the inner wall of the clamping hole limiting block (32), and one end of the clamping hole limiting block (32) is inserted into the inner wall of the round hole frame (33).
6. A multi-stage rectification column according to claim 5, characterized in that: The cross section of the clamping block (35) is trapezoidal, and the size of one end of the clamping block (35) close to the round rod (34) is larger than that of the other end.
7. A multi-stage rectification column according to claim 5, characterized in that: One end of the round rod (34) is fixedly connected with a pull block (37), the longitudinal section of the pull block (37) is circular.
8. A multi-stage rectification column according to claim 5, characterized in that: The outer surfaces of both sides of one end of the clamping hole limiting block (32) are fixedly connected with bearings (38), and the outer rings of the bearings (38) are fixedly connected with the inner walls of the U-shaped blocks (31).