Bell mouth structure of steel pipe flexible connector

Abstract

The utility model discloses a bellmouth structure of a steel pipe flexible connector, which comprises a bellmouth steel pipe, a conveying steel pipe is arranged at the rear end of the bellmouth steel pipe, a bearing platform is arranged at the joint of the bellmouth steel pipe and the conveying steel pipe, a sealing gasket is mounted at the bearing platform, and the sealing gasket is detachably connected with the bearing platform; a plurality of sealing assemblies are arranged on the inner side face of the socket steel pipe from front to back, each sealing assembly comprises an installation ring and a sealing ring, the sealing rings and the installation rings are connected together in a clamped mode, elastic supporting rings are arranged on the inner sides of the installation rings, and the elastic supporting rings are connected to the inner sides of the sealing rings in an inserted mode. The bearing platform is arranged at the joint of the socket steel pipe and the conveying steel pipe, the sealing gasket is installed on the bearing platform, the inserting steel pipe is inserted into the inner side of the socket steel pipe and then abuts against the sealing gasket, and therefore the first sealing effect is achieved; and a plurality of sealing assemblies are arranged on the inner side face of the socket steel pipe, and the sealing assemblies can well seal the socket steel pipe and the inserting steel pipe.

Description

Technical Field

[0001] The utility model relates to the technical field of steel pipe connection, in particular to a socket structure of a steel pipe flexible interface. Background Art

[0002] While rigid joints offer high connection strength, they lack flexibility. When subjected to external forces such as earthquakes and soil subsidence, they are prone to breakage or leakage, impacting the normal operation and service life of the piping system. Furthermore, rigid connections require high installation precision, making the installation process cumbersome, labor-intensive, and time-consuming. To address the drawbacks of rigid steel pipe joints, new types of steel pipes with flexible connections are now available on the market.

[0003] For example, a Chinese patent with publication number CN209725537U discloses a connection structure for connecting a large-diameter plastic-coated steel pipe socket structure, comprising a socket end of a steel pipe and a spigot end of a steel pipe that are plugged into each other. The port of the spigot end of the steel pipe is provided with a necking structure, and the port of the socket end of the steel pipe is provided with an expanding structure. The gap between the inner wall of the pipe wall of the socket end of the steel pipe and the outer wall of the pipe wall of the spigot end of the steel pipe is 0.5-2 cm; an annular limiting boss is provided outwardly on the outer pipe wall of the spigot end of the steel pipe, and a gap is provided between the necking structure and the first circular arc transition section.

[0004] The connection method of the steel pipe socket structure provided by the above patent is a flexible connection, which has the advantages of low-cost connection accessories and short construction time. It can also adapt to small-angle winding laying and can withstand a certain degree of foundation settlement. It also has a sealing structure, which mainly achieves the sealing effect by plugging a steel pipe with a socket and a steel pipe with a plug-in structure into each other, and the sealing effect is achieved by a sealing ring inside the socket. However, the cushioning effect of this sealing ring is poor, and relying solely on a sealing ring is not enough to effectively seal the socket part of the steel pipe. Utility Model Content

[0005] The purpose of this utility model is to provide a socket structure for a flexible joint of a steel pipe, aiming to improve the problem that the cushioning effect of the sealing ring at the socket of the existing flexible connection structure is poor, and that relying solely on a sealing ring cannot effectively seal the socket part of the steel pipe.

[0006] The utility model is achieved in this way:

[0007] A socket structure for a flexible steel pipe interface comprises a socket steel pipe, a conveying steel pipe is provided at the rear end of the socket steel pipe, a pedestal is provided at the junction of the socket steel pipe and the conveying steel pipe, a sealing gasket is installed at the pedestal, and the sealing gasket and the pedestal are detachably connected; and a plurality of sealing assemblies are provided on the inner side surface of the socket steel pipe from front to back, the sealing assemblies comprise a mounting ring and a sealing ring, the sealing ring is clamped together with the mounting ring, and an elastic support ring is provided on the inner side of the mounting ring, and the elastic support ring is inserted into the inner side of the sealing ring.

[0008] Preferably, an annular groove is provided on the inner side surface of the socket steel pipe, and a threaded groove is provided in the middle of the support platform.

[0009] Preferably, the surface of the sealing gasket facing the base is provided with a reinforcement ring, and the reinforcement ring and the sealing gasket are glued together; the surface of the reinforcement ring facing the base is provided with an adapter ring, and the adapter ring is threadedly connected to the thread groove.

[0010] Preferably, the inner side surface of the mounting ring is symmetrically provided with grooves along both sides of the elastic support ring, and the cross section of the groove is L-shaped.

[0011] Preferably, a limiting groove is provided in the middle of the outer side surface of the sealing ring, the limiting groove is sleeved on the elastic support ring, and snap rings are provided on both sides of the limiting groove, and the snap rings are engaged with the inner side of the snap groove.

[0012] Preferably, it further comprises a sealing sleeve, the cross section of which is a U-shaped structure, and the sealing sleeve is arranged on the end of the socket steel pipe.

[0013] Preferably, the socket steel pipe is evenly provided with a plurality of limiting holes near the front end, the sealing sleeve is provided with a sleeve groove on the side facing the socket steel pipe, and a plurality of limiting posts are evenly provided on the inner ring of the inner bottom edge of the sleeve groove, and the limiting posts are inserted into the limiting holes;

[0014] Preferably, a tightening assembly is further included, and an installation groove is provided on the outer side surface of the sealing sleeve, and the tightening assembly is engaged in the installation groove.

[0015] Preferably, the tightening assembly includes a first tightening piece, a second tightening piece and a tightening bolt, a first connecting column is provided at both ends of the first tightening piece, a countersunk hole is provided in the middle of the first connecting column, a second connecting column is provided at both ends of the second tightening piece, a threaded hole is provided in the middle of the second connecting column, and the tightening bolt passes through the countersunk hole and is threadedly connected to the threaded hole.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. This utility model provides a pedestal at the connection between the socket steel pipe and the delivery steel pipe, on which a sealing gasket is installed. After the splice steel pipe is inserted into the inner side of the socket steel pipe, it abuts against the sealing gasket, thereby providing the first seal. At the same time, multiple sealing assemblies are provided on the inner side of the socket steel pipe to ensure a good seal between the socket steel pipe and the splice steel pipe. An elastic support ring is provided on the inner side of the sealing assembly to provide a certain buffering effect on the steel pipe when it vibrates.

[0018] 2. The utility model provides a sealing sleeve on the end of the socket steel pipe, which can effectively protect and seal the end of the socket steel pipe.

[0019] 3. The utility model tightens the sealing sleeve on the end of the socket steel pipe through the tightening component, so that the end of the socket steel pipe and the steel pipe plugged therein are effectively sealed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of the utility model as a whole;

[0021] Figure 2 This is a structural diagram of the socket steel pipe of the utility model;

[0022] Figure 3 It is a structural diagram of the sealing gasket of the utility model;

[0023] Figure 4 It is a structural diagram of the sealing assembly of the utility model;

[0024] Figure 5 This is a schematic structural diagram of the sealing sleeve of the utility model;

[0025] Figure 6 It is a structural diagram of the tightening component of the utility model.

[0026] In the figure: 1. socket steel pipe; 11. conveying steel pipe; 12. ring groove; 13. base; 14. threaded groove; 15. limiting hole; 2. sealing gasket; 21. reinforcement ring; 22. adapter ring; 3. sealing assembly; 31. mounting ring; 311. snap groove; 312. elastic support ring; 32. sealing ring; 321. snap ring; 322. limiting groove; 4. sealing sleeve; 41. sleeve groove; 42. limiting column; 43. mounting groove; 5. tightening assembly; 51. first tightening piece; 511. first connecting column; 512. countersunk hole; 52. second tightening piece; 521. second connecting column; 522. threaded hole; 53. tightening bolt. DETAILED DESCRIPTION

[0027] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, indirect connection through an intermediate medium, internal communication between two components, or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0028] The following is a further description with reference to the accompanying drawings and specific embodiments:

[0029] Example 1

[0030] like Figure 1 、 Figure 2 and Figure 4 As shown, a socket structure of a flexible interface of a steel pipe includes a socket steel pipe 1. The socket steel pipe 1 is convenient for plugging and connecting with the corresponding steel pipe, and facilitates the flexible connection between the steel pipes. A conveying steel pipe 11 is provided at the rear end of the socket steel pipe 1, and the conveying steel pipe 11 is used to convey materials. A base 13 is provided at the junction of the socket steel pipe 1 and the conveying steel pipe 11, and a sealing gasket 2 is installed on the base 13. The sealing gasket 2 and the base 13 are detachably connected; the base 13 is convenient for the plug-in steel pipe to rest against its upper part, and the sealing gasket 2 facilitates the effective sealing between the plug-in steel pipe and the base 13; the inner side surface of the socket steel pipe 1 is provided with multiple sealing components 3 from front to back, and the sealing components 3 are convenient for sealing between the socket steel pipe 1 and the plug-in steel pipe. The sealing component 3 includes a mounting ring 31 and a sealing ring 32. The sealing ring 32 is connected to the mounting ring 31. This structure is convenient for replacing the sealing ring 32 after the sealing ring 32 is damaged. An elastic support ring 312 is provided on the inner side of the mounting ring 31 , and the elastic support ring 312 is plugged into the inner side of the sealing ring 32 . This structure facilitates the elastic support ring 312 to play a buffering role when the pipeline vibrates.

[0031] like Figure 2 As shown, the inner side of the bell-end steel pipe 1 is provided with an annular groove 12, which is convenient for connecting the bell-end steel pipe 1 with the sealing assembly 3. A threaded groove 14 is provided in the middle of the support 13, which is convenient for connecting with the sealing gasket 2.

[0032] like Figure 3 As shown, the surface of the sealing gasket 2 facing the base 13 is provided with a reinforcement ring 21, which is glued to the sealing gasket 2; the reinforcement ring 21 ensures sufficient stability of the sealing gasket 2. The surface of the reinforcement ring 21 facing the base 13 is provided with an adapter ring 22, which is threadedly connected to the thread groove 14. This structure facilitates the smooth thread connection of the sealing gasket 2 with the thread groove 14.

[0033] like Figure 4As shown, the inner side of the mounting ring 31 is symmetrically provided with snap-in grooves 311 along either side of the elastic support ring 312. The cross-section of the snap-in grooves 311 is L-shaped; this structure facilitates the stable connection of the mounting ring 31 to the sealing ring 32. A retaining groove 322 is provided in the middle of the outer side of the sealing ring 32. The elastic support ring 312 is positioned within the retaining groove 322, ensuring the stable engagement of the sealing ring 32 with the mounting ring 31. Snap rings 321 are provided on either side of the retaining groove 322, which engage the inner side of the snap-in grooves 311. The snap rings 321 and the snap-in grooves 311 ensure a stable and removable connection between the sealing ring 32 and the mounting ring 31.

[0034] Working principle: When in use, connect the sealing gasket 2 and the base 13, and then install the sealing assembly 3 in the annular groove 12 on the inner side of the socket; then insert the splicing steel pipe into the inner side of the socket steel pipe 1, and make the splicing steel pipe rest on the sealing gasket 2. The sealing gasket 2 can make the splicing steel pipe and the socket steel pipe 1 stably connected. At the same time, the sealing gasket 2 and the sealing assembly 3 can form a multi-channel sealing structure, which ensures good sealing between the socket steel pipe 1 and the splicing steel pipe, and improves the sealing between the flexible connecting steel pipes. Compared with the prior art, the present application provides a base 13 at the connection between the socket steel pipe 1 and the conveying steel pipe 11, and a sealing gasket 2 is installed on the base 13. After the splicing steel pipe is inserted into the inner side of the socket steel pipe 1, it rests on the sealing gasket 2, thereby playing the role of the first seal; and the inner side of the socket steel pipe 1 is provided with a plurality of sealing components 3, and the sealing components 3 can perform a good seal between the socket steel pipe 1 and the splicing steel pipe; and an elastic support ring 312 is provided on the inner side of the sealing component 3, which can play a certain buffering role on the steel pipe when the steel pipe vibrates.

[0035] Example 2

[0036] like Figure 1 、 Figure 2 and Figure 4As shown, a socket structure of a flexible interface of a steel pipe includes a socket steel pipe 1. The socket steel pipe 1 is convenient for plugging and connecting with the corresponding steel pipe, and facilitates the flexible connection between the steel pipes. A conveying steel pipe 11 is provided at the rear end of the socket steel pipe 1, and the conveying steel pipe 11 is used to convey materials. A base 13 is provided at the junction of the socket steel pipe 1 and the conveying steel pipe 11, and a sealing gasket 2 is installed on the base 13. The sealing gasket 2 and the base 13 are detachably connected; the base 13 is convenient for the plug-in steel pipe to rest against its upper part, and the sealing gasket 2 facilitates the effective sealing between the plug-in steel pipe and the base 13; the inner side surface of the socket steel pipe 1 is provided with multiple sealing components 3 from front to back, and the sealing components 3 are convenient for sealing between the socket steel pipe 1 and the plug-in steel pipe. The sealing component 3 includes a mounting ring 31 and a sealing ring 32. The sealing ring 32 is connected to the mounting ring 31. This structure is convenient for replacing the sealing ring 32 after the sealing ring 32 is damaged. An elastic support ring 312 is provided on the inner side of the mounting ring 31 , and the elastic support ring 312 is plugged into the inner side of the sealing ring 32 . This structure facilitates the elastic support ring 312 to play a buffering role when the pipeline vibrates.

[0037] like Figure 2 As shown, the inner side of the bell-end steel pipe 1 is provided with an annular groove 12, which is convenient for connecting the bell-end steel pipe 1 with the sealing assembly 3. A threaded groove 14 is provided in the middle of the support 13, which is convenient for connecting with the sealing gasket 2.

[0038] like Figure 3 As shown, the surface of the sealing gasket 2 facing the base 13 is provided with a reinforcement ring 21, which is glued to the sealing gasket 2; the reinforcement ring 21 ensures sufficient stability of the sealing gasket 2. The surface of the reinforcement ring 21 facing the base 13 is provided with an adapter ring 22, which is threadedly connected to the thread groove 14. This structure facilitates the smooth thread connection of the sealing gasket 2 with the thread groove 14.

[0039] like Figure 4 As shown, the inner side of the mounting ring 31 is symmetrically provided with snap-in grooves 311 along either side of the elastic support ring 312. The cross-section of the snap-in grooves 311 is L-shaped; this structure facilitates the stable connection of the mounting ring 31 to the sealing ring 32. A retaining groove 322 is provided in the middle of the outer side of the sealing ring 32. The elastic support ring 312 is positioned within the retaining groove 322, ensuring the stable engagement of the sealing ring 32 with the mounting ring 31. Snap rings 321 are provided on either side of the retaining groove 322, which engage the inner side of the snap-in grooves 311. The snap rings 321 and the snap-in grooves 311 ensure a stable and removable connection between the sealing ring 32 and the mounting ring 31.

[0040] like Figure 1 and Figure 5As shown, it also includes a sealing sleeve 4, the cross-section of which is a U-shaped structure, and the sealing sleeve 4 is sleeved on the end of the socket steel pipe 1. This structure is convenient for the sealing platform to seal the gap between the socket steel pipe 1 and the plug-in steel pipe. The socket steel pipe 1 is evenly provided with a plurality of limiting holes 15 near the front end, and the limiting holes 15 are convenient for mutual limitation with the sealing sleeve 4. The sealing sleeve 4 is provided with a sleeve groove 41 on the side facing the socket steel pipe 1, and the sleeve groove 41 is convenient for being sleeved on the end of the socket steel pipe 1. A plurality of limiting columns 42 are evenly provided on the inner ring of the inner bottom edge of the sleeve groove 41, and the limiting columns 42 are inserted into the limiting holes 15; this structure ensures that the sealing sleeve 4 is stably sleeved on the end of the socket steel pipe 1.

[0041] Example 3

[0042] like Figure 1 、 Figure 2 and Figure 4 As shown, a socket structure of a flexible interface of a steel pipe includes a socket steel pipe 1. The socket steel pipe 1 is convenient for plugging and connecting with the corresponding steel pipe, and facilitates the flexible connection between the steel pipes. A conveying steel pipe 11 is provided at the rear end of the socket steel pipe 1, and the conveying steel pipe 11 is used to convey materials. A base 13 is provided at the junction of the socket steel pipe 1 and the conveying steel pipe 11, and a sealing gasket 2 is installed on the base 13. The sealing gasket 2 and the base 13 are detachably connected; the base 13 is convenient for the plug-in steel pipe to rest against its upper part, and the sealing gasket 2 facilitates the effective sealing between the plug-in steel pipe and the base 13; the inner side surface of the socket steel pipe 1 is provided with multiple sealing components 3 from front to back, and the sealing components 3 are convenient for sealing between the socket steel pipe 1 and the plug-in steel pipe. The sealing component 3 includes a mounting ring 31 and a sealing ring 32. The sealing ring 32 is connected to the mounting ring 31. This structure is convenient for replacing the sealing ring 32 after the sealing ring 32 is damaged. An elastic support ring 312 is provided on the inner side of the mounting ring 31 , and the elastic support ring 312 is plugged into the inner side of the sealing ring 32 . This structure facilitates the elastic support ring 312 to play a buffering role when the pipeline vibrates.

[0043] like Figure 2 As shown, the inner side of the bell-end steel pipe 1 is provided with an annular groove 12, which is convenient for connecting the bell-end steel pipe 1 with the sealing assembly 3. A threaded groove 14 is provided in the middle of the support 13, which is convenient for connecting with the sealing gasket 2.

[0044] like Figure 3 As shown, the surface of the sealing gasket 2 facing the base 13 is provided with a reinforcement ring 21, which is glued to the sealing gasket 2; the reinforcement ring 21 ensures sufficient stability of the sealing gasket 2. The surface of the reinforcement ring 21 facing the base 13 is provided with an adapter ring 22, which is threadedly connected to the thread groove 14. This structure facilitates the smooth thread connection of the sealing gasket 2 with the thread groove 14.

[0045] like Figure 4As shown, the inner side of the mounting ring 31 is symmetrically provided with snap-in grooves 311 along either side of the elastic support ring 312. The cross-section of the snap-in grooves 311 is L-shaped; this structure facilitates the stable connection of the mounting ring 31 to the sealing ring 32. A retaining groove 322 is provided in the middle of the outer side of the sealing ring 32. The elastic support ring 312 is positioned within the retaining groove 322, ensuring the stable engagement of the sealing ring 32 with the mounting ring 31. Snap rings 321 are provided on either side of the retaining groove 322, which engage the inner side of the snap-in grooves 311. The snap rings 321 and the snap-in grooves 311 ensure a stable and removable connection between the sealing ring 32 and the mounting ring 31.

[0046] like Figure 1 and Figure 5 As shown, it also includes a sealing sleeve 4, the cross-section of which is a U-shaped structure, and the sealing sleeve 4 is sleeved on the end of the socket steel pipe 1. This structure is convenient for the sealing platform to seal the gap between the socket steel pipe 1 and the plug-in steel pipe. The socket steel pipe 1 is evenly provided with a plurality of limiting holes 15 near the front end, and the limiting holes 15 are convenient for mutual limitation with the sealing sleeve 4. The sealing sleeve 4 is provided with a sleeve groove 41 on the side facing the socket steel pipe 1, and the sleeve groove 41 is convenient for being sleeved on the end of the socket steel pipe 1. A plurality of limiting columns 42 are evenly provided on the inner ring of the inner bottom edge of the sleeve groove 41, and the limiting columns 42 are inserted into the limiting holes 15; this structure ensures that the sealing sleeve 4 is stably sleeved on the end of the socket steel pipe 1.

[0047] like Figure 1 and Figure 6 As shown, the invention also includes a tightening assembly 5. The outer side of the sealing sleeve 4 is provided with a mounting groove 43, and the tightening assembly 5 is engaged with the mounting groove 43. This structure facilitates the tightening assembly 5 to stably tighten the sealing sleeve 4, ensuring that the sealing sleeve 4 is stably connected to the socket steel pipe 1. The tightening assembly 5 includes a first tightening member 51, a second tightening member 52, and a tightening bolt 53. The tightening bolt 53 connects and tightens the first tightening member 51 and the second tightening member 52, ensuring that the first tightening member 51 and the second tightening member 52 stably install the sealing sleeve 4 on the end of the socket steel pipe 1. A first connecting column 511 is provided at both ends of the first tightening member 51, and a countersunk hole 512 is provided in the middle of the first connecting column 511. A second connecting column 521 is provided at both ends of the second tightening member 52, and a threaded hole 522 is provided in the middle of the second connecting column 521. The tightening bolt 53 passes through the countersunk hole 512 and is threadedly connected to the threaded hole 522; the tightening bolt 53 is convenient for passing through the countersunk hole 512, and the threaded hole 522 is convenient for the tightening bolt 53 to be threadedly connected to the threaded hole 522.

[0048] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A socket structure for a flexible steel pipe joint, comprising a socket steel pipe (1), characterized in that: The rear end of the bell-end steel pipe (1) is provided with a conveying steel pipe (11), and a support (13) is provided at the connection between the bell-end steel pipe (1) and the conveying steel pipe (11), and a sealing gasket (2) is installed at the support (13), and the sealing gasket (2) and the support (13) are detachably connected; and the inner side surface of the bell-end steel pipe (1) is provided with a plurality of sealing components (3) from front to back, and the sealing components (3) include a mounting ring (31) and a sealing ring (32), and the sealing ring (32) is clamped together with the mounting ring (31), and an elastic support ring (312) is provided on the inner side of the mounting ring (31), and the elastic support ring (312) is inserted into the inner side of the sealing ring (32).

2. The socket structure of a flexible steel pipe joint according to claim 1, characterized in that: The inner side surface of the socket steel pipe (1) is provided with an annular groove (12), and the middle part of the support platform (13) is provided with a thread groove (14).

3. The socket structure of a flexible steel pipe joint according to claim 2, characterized in that: The surface of the sealing gasket (2) facing the support platform (13) is provided with a reinforcement ring (21), and the reinforcement ring (21) and the sealing gasket (2) are glued together; the surface of the reinforcement ring (21) facing the support platform (13) is provided with an adapter ring (22), and the adapter ring (22) is threadedly connected to the thread groove (14).

4. The socket structure of a flexible steel pipe joint according to claim 1, characterized in that: The inner side surface of the mounting ring (31) is symmetrically provided with clamping grooves (311) along both sides of the elastic support ring (312), and the cross section of the clamping grooves (311) is L-shaped.

5. The socket structure of a flexible steel pipe joint according to claim 4, characterized in that: A limiting groove (322) is provided in the middle of the outer side surface of the sealing ring (32), and the limiting groove (322) is sleeved on the elastic support ring (312). Snap rings (321) are provided on both sides of the limiting groove (322), and the snap rings (321) are engaged with the inner side of the snap groove (311).

6. The socket structure of a flexible steel pipe joint according to any one of claims 1 to 5, characterized in that: It also includes a sealing sleeve (4), the cross section of which is a U-shaped structure, and the sealing sleeve (4) is sleeved on the end of the socket steel pipe (1).

7. The socket structure of a flexible steel pipe joint according to claim 6, characterized in that: The socket steel pipe (1) is evenly provided with a plurality of limiting holes (15) near the front end, the sealing sleeve (4) is provided with a sleeve groove (41) on the side facing the socket steel pipe (1), and the inner bottom edge of the sleeve groove (41) is evenly provided with a plurality of limiting columns (42) on the inner ring, and the limiting columns (42) are inserted into the limiting holes (15).

8. The socket structure of a flexible steel pipe joint according to claim 7, characterized in that: It also includes a tightening assembly (5), an outer side surface of the sealing sleeve (4) is provided with a mounting groove (43), and the tightening assembly (5) is engaged in the mounting groove (43).

9. The socket structure of a flexible steel pipe joint according to claim 8, characterized in that: The tightening assembly (5) includes a first tightening member (51), a second tightening member (52) and a tightening bolt (53), wherein both ends of the first tightening member (51) are provided with a first connecting column (511), and a countersunk hole (512) is provided in the middle of the first connecting column (511), and both ends of the second tightening member (52) are provided with a second connecting column (521), and a threaded hole (522) is provided in the middle of the second connecting column (521), and the tightening bolt (53) passes through the countersunk hole (512) and is threadedly connected to the threaded hole (522).

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