CN115363564A

CN115363564A - Neck magnetic resonance imaging coil sliding positioning device for Parkinson's disease

Info

Publication number: CN115363564A
Application number: CN202211129899.8A
Authority: CN
Inventors: 李海宁; 成江; 徐婷; 宣婷婷; 张俊梅; 祁为民
Original assignee: General Hospital of Ningxia Medical University
Current assignee: General Hospital of Ningxia Medical University
Priority date: 2022-09-16
Filing date: 2022-09-16
Publication date: 2022-11-22

Abstract

The invention discloses a head and neck nuclear magnetic resonance imaging coil sliding positioning device for Parkinson's disease, which comprises a bed body, wherein handrails are arranged on two sides of the bed body. The two-way threaded rod is driven by the servo motor to rotate, so that the two-way threaded rod drives the two movable adjusting blocks to relatively move along the strip-shaped opening under the limiting action of the sliding groove and the sliding block, the two movable adjusting blocks drive the neck cushion block to be in contact with the neck of a patient, the neck of the patient is effectively positioned, the hydraulic cylinder drives the second arc-shaped seat to move towards the first arc-shaped seat under the limiting action of the movable plate and the supporting rod, and the first spring in the groove is matched with the arc-shaped buffer block on the second fixed rod and the arc-shaped protection pad in the first arc-shaped seat to clamp and position the head of the patient.

Description

Neck magnetic resonance imaging coil sliding positioning device for Parkinson's disease

Technical Field

The invention relates to the technical field of medical equipment, in particular to a head and neck nuclear magnetic resonance imaging coil sliding positioning device for Parkinson's disease.

Background

The nuclear magnetic resonance imaging of the head and the neck can diagnose soft tissue tumors and other diseases of the head and the neck, the nuclear magnetic resonance examination can carry out multi-angle and multi-plane imaging on each part of a human body, the resolution ratio is very high, the internal structure of the human body and the position relation of adjacent organs can be objectively and specifically displayed, the Parkinson disease is a nervous system disease, the body of a patient can shake involuntarily, and the Parkinson disease can be relieved for a long time without any method.

When the existing head and neck nuclear magnetic resonance imaging coil is actually used, the head and neck of a Parkinson patient cannot be conveniently positioned, a head and neck protection structure is lacked, the head and neck of the Parkinson patient are easily damaged, and the problem is solved by the sliding positioning device of the head and neck nuclear magnetic resonance imaging coil for the Parkinson disease.

Disclosure of Invention

The invention provides a sliding positioning device for a neck nuclear magnetic resonance imaging coil for Parkinson's disease, which is used for solving the technical problems that the existing neck nuclear magnetic resonance imaging coil in the background technology is inconvenient to position the head and neck of a Parkinson patient when in actual use, lacks a head and neck protection structure and is easy to damage the head and neck of the Parkinson patient.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a neck magnetic resonance imaging coil slide positioning device for parkinson's disease, includes the bed body, the both sides of the bed body are equipped with the handrail, the upper end that the bed body is close to right rear side is equipped with the driving piece, the internal cavity that is equipped with of bed, be equipped with the bar opening on the cavity top surface, the right side inner wall of cavity is improved level and is run through and be equipped with adjustment mechanism, the driving piece is connected with the adjustment mechanism transmission, adjustment mechanism runs through the bar opening setting, adjustment mechanism is located the outer one end in cavity and is equipped with neck positioning mechanism, the bed body is close to the first arc seat of upper end fixedly connected with of rear side, be equipped with second arc seat directly over the first arc seat, the upper end of second arc seat is equipped with elevating system, be equipped with same head positioning mechanism on the relative inner wall of first arc seat and second arc seat, be equipped with stop gear between first arc seat and the second arc seat.

Preferably, the driving part comprises a servo motor fixedly installed on the bed body and close to the upper end of the right rear side, a rotating shaft is fixedly connected to a driving shaft of the servo motor, a first gear is coaxially and fixedly connected to the rotating shaft, and the first gear is in transmission connection with the adjusting mechanism.

Preferably, adjustment mechanism includes that the level rotates the connecting rod that runs through cavity right side inner wall setting, the connecting rod is located the outer one of cavity and serves coaxial fixedly connected with second gear, first gear and second gear meshing, the connecting rod is located the one end fixedly connected with two-way threaded rod in the cavity, the one end that the connecting rod was kept away from to two-way threaded rod is connected with the left side inner wall rotation of cavity, two movable adjusting block have been cup jointed to the last screw thread of two-way threaded rod the lower extreme of movable adjusting block all with the bottom sliding connection of cavity, two the bar opening setting is all run through to the upper end of movable adjusting block, neck positioning mechanism sets up in two movable adjusting block and is located the outer upper end of bar opening.

Preferably, friction weld is fixed between connecting rod and the two-way threaded rod, be equipped with the spout on the bottom of cavity, sliding connection has two assorted sliders with it in the spout, two the upper end of slider respectively with the lower extreme fixed connection of two movable adjusting blocks, the spout is isometric setting with the bar opening.

Preferably, the neck positioning mechanism comprises first circular grooves arranged at the upper ends of the two movable adjusting blocks, two hydraulic buffers are fixedly connected to the bottoms of the first circular grooves, two first fixing rods are fixedly connected to the upper ends of the hydraulic buffers, and two neck cushion blocks are fixedly connected to the upper ends of the first fixing rods.

Preferably, elevating system includes bracing piece and the fly leaf of fixed connection in first arc seat upper end that the bed body is located first arc seat left and right sides upper end respectively, two the equal vertical fly leaf setting that runs through in upper end of bracing piece, two the same fixed plate of upper end fixedly connected with of bracing piece, the upper end fixed mounting that the fixed plate is located central point and puts has the pneumatic cylinder, the lower extreme of pneumatic cylinder piston rod is vertical to run through the fixed plate setting and is located the upper end fixed connection that central point put with the fly leaf.

Preferably, head positioning mechanism includes arc protection pad of difference fixed connection on first arc seat arc inner wall and sets up two recesses on second arc seat arc inner wall, two equal fixedly connected with first spring, two on the inner wall of recess the equal fixedly connected with second dead lever of one end that the recess inner wall was kept away from to first spring, two the equal fixedly connected with arc buffer block of one end that first spring was kept away from to the second dead lever.

Preferably, the neck cushion block, the arc-shaped protection pad and the arc-shaped buffer block are all made of polyurethane rubber.

Preferably, stop gear is including setting up two second circular recesses on first arc seat and the relative lateral wall of second arc seat respectively, with one side two the second circular recess is close to the setting of both ends lateral wall about first arc seat and second arc seat respectively, two relatively equal fixedly connected with second spring on the relative inner wall of second circular recess, and is a plurality of the equal fixedly connected with circular piece of one end that the second spring kept away from the second circular recess inner wall, two are relative be equipped with same root of cylindricality piece between the circular piece, a plurality of all be equipped with annular spacing groove on the annular inner wall of second circular recess, circular piece slides the counterbalance contact with the annular inner wall of annular spacing groove, circular piece and cylindricality piece are the integrated into one piece setting.

Compared with the prior art, the invention has the beneficial effects that:

1. drive two-way threaded rod through servo motor and rotate for two-way threaded rod drives two movable adjusting blocks along bar opening relative movement under the limiting displacement of spout and slider, and drives neck cushion and patient's neck contact by two movable adjusting blocks, effectively fixes a position patient's neck.

2. Drive second arc seat through the pneumatic cylinder and remove to first arc seat under the limiting displacement of fly leaf and bracing piece to carry out the centre gripping location to patient's head by the arc buffer block on the first spring cooperation second dead lever in the recess and the arc protection pad in the first arc seat, the neck cushion of polyurethane rubber goods, arc protection pad and arc buffer block can provide the buffering protection to patient's neck portion simultaneously, avoid causing the injury to patient's neck portion.

Drawings

Fig. 1 is a schematic structural view of a head and neck magnetic resonance imaging coil sliding positioning device for parkinson's disease provided by the invention;

fig. 2 is a perspective schematic view of a head and neck magnetic resonance imaging coil sliding positioning device for parkinson's disease according to the present invention;

FIG. 3 is an enlarged view of a portion A of FIG. 2;

fig. 4 is a schematic structural view of a first fixing rod and a neck cushion block of the head and neck mri coil sliding positioning device for parkinson's disease provided by the invention;

FIG. 5 is an enlarged view of a portion of FIG. 2 at B;

fig. 6 is a schematic structural view of a second fixing rod and an arc-shaped buffer block of the head and neck mri coil sliding positioning device for parkinson's disease provided by the invention;

FIG. 7 is an enlarged view of a portion of FIG. 2 at C;

fig. 8 is a schematic structural diagram of a circular block and a cylindrical block of the head and neck mri coil sliding positioning device for parkinson's disease provided by the invention.

In the figure: the device comprises a bed body 1, a handrail 2, a chamber 3, a strip-shaped opening 4, a first arc-shaped seat 5, a second arc-shaped seat 6, a servo motor 7, a rotating shaft 8, a first gear 9, a connecting rod 10, a second gear 11, a two-way threaded rod 12, a movable adjusting block 13, a sliding chute 14, a sliding block 15, a first circular groove 16, a hydraulic buffer 17, a first fixing rod 18, a neck cushion block 19, a supporting rod 20, a movable plate 21, a fixed plate 22, a hydraulic cylinder 23, an arc-shaped protection pad 24, a groove 25, a first spring 26, a second fixing rod 27, an arc-shaped buffer block 28, a second circular groove 29, a second spring 30, a circular block 31, a cylindrical block 32 and an annular limiting groove 33.

Detailed Description

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Referring to fig. 1-8, a neck magnetic resonance imaging coil slide positioning device for parkinson's disease, including the bed body 1, the both sides of bed body 1 are equipped with handrail 2, and bed body 1 is close to the upper end of right rear side and is equipped with the driving piece, and the driving piece includes servo motor 7 of fixed mounting in bed body 1 near right rear side upper end, and servo motor 7's model is: MSME-012S1, a servo motor 7 is used for driving a first gear 9 on a rotating shaft 8 to rotate, the rotating shaft 8 is fixedly connected on a driving shaft of the servo motor 7, the first gear 9 is coaxially and fixedly connected on the rotating shaft 8, the first gear 9 is in transmission connection with an adjusting mechanism, a chamber 3 is arranged in the bed body 1, a strip-shaped opening 4 is arranged on the top surface of the chamber 3, the adjusting mechanism is horizontally arranged on the inner wall of the right side of the chamber 3 in a penetrating way, a driving part is in transmission connection with the adjusting mechanism and is arranged through the strip-shaped opening 4, the adjusting mechanism comprises a connecting rod 10 which is horizontally arranged and rotatably arranged through the inner wall of the right side of the chamber 3, a second gear 11 is coaxially and fixedly connected on one end of the connecting rod 10 positioned outside the chamber 3, the first gear 9 is meshed with the second gear 11, the first gear 9 rotates to drive a second gear 11 meshed with the first gear to rotate, and the connecting rod 10 which is coaxially connected is driven by the second gear 11 to rotate, the connecting rod 10 drives the two-way threaded rod 12 to rotate simultaneously, one end of the connecting rod 10, which is positioned in the cavity 3, is fixedly connected with the two-way threaded rod 12, one end of the two-way threaded rod 12, which is far away from the connecting rod 10, is rotatably connected with the inner wall of the left side of the cavity 3, two movable adjusting blocks 13 are sleeved on the two-way threaded rod 12 in a threaded manner, the lower ends of the two movable adjusting blocks 13 are both in sliding connection with the bottom of the cavity 3, the upper ends of the two movable adjusting blocks 13 are both arranged by penetrating through the strip-shaped opening 4, the two movable adjusting blocks 13 sleeved with the threads are driven by the rotation of the two-way threaded rod 12 to move relatively along the strip-shaped opening 4 under the limiting action of the sliding chute 14 and the sliding block 15 until the two movable adjusting blocks 13 respectively drive the two neck cushion blocks 19 to be contacted with the neck of a patient, so that the neck cushion block 19 is stressed to drive the first fixing rod 18 to compress the hydraulic buffer 17 in the first circular groove 16, thereby make hydraulic buffer 17 cooperate first dead lever 18 to drive two neck cushion blocks 19 and fix a position patient's neck, neck positioning mechanism sets up in the upper end that two movable regulating block 13 are located bar opening 4 outward.

Friction weld is fixed between connecting rod 10 and two-way threaded rod 12, be equipped with spout 14 on the bottom of cavity 3, sliding connection has two assorted sliders 15 with it in spout 14, the upper end of two sliders 15 respectively with the lower extreme fixed connection of two movable regulating blocks 13, spout 14 is isometric setting with bar opening 4, slider 15 when removing in spout 14, can prevent that two-way threaded rod 12 from rotating the movable regulating block 13 that drives the screw thread and cup joint and rotate simultaneously, the range of movement of restriction movable regulating block 13, the one end that adjustment mechanism is located outside cavity 3 is equipped with neck positioning mechanism, neck positioning mechanism is including setting up in the first circular recess 16 of two movable regulating blocks 13 upper ends, equal fixedly connected with hydraulic buffer 17 on the bottom of two first circular recesses 16, the equal fixedly connected with first dead lever 18 in upper end of two hydraulic buffer 17, the equal fixedly connected with neck cushion 19 in upper end of two first dead levers 18, hydraulic buffer 17 cooperates neck cushion 19 to fix a position patient's neck, the elasticity performance of hydraulic buffer 17 and the neck 19 of polyurethane rubber goods can lead to the fact the cushion to the injury to the patient's neck, avoid causing the injury to the patient's neck.

The bed body 1 is close to the first arc seat 5 of upper end fixedly connected with of rear side, be equipped with second arc seat 6 directly over first arc seat 5, the upper end of second arc seat 6 is equipped with elevating system, elevating system includes bracing piece 20 and the fly leaf 21 of fixed connection in 5 upper ends of first arc seat 5 left and right sides of fixed connection respectively in bed body 1, the equal vertical fly leaf 21 setting that runs through in upper end of two spinal branch vaulting poles 20, the same fixed plate 22 of upper end fixedly connected with of two spinal branch vaulting poles 20, the upper end fixed mounting that fixed plate 22 is located central point and puts has pneumatic cylinder 23, pneumatic cylinder 23's model is: HOB60 120, pneumatic cylinder 23 is used for driving second arc seat 6 on the fly leaf 21 to be close to first arc seat 5, until two arc buffer blocks 28 and patient's head contact, arc buffer block 28 atress this moment drives second dead lever 27 compression recess 25 in first spring 26, thereby make two arc buffer blocks 28 cooperate the arc protection pad 24 in the first arc seat 5 to carry out the centre gripping location to patient's head, the vertical upper end fixed connection that runs through fixed plate 22 setting and be located the central point with fly leaf 21 of the lower extreme of pneumatic cylinder 23 piston rod.

Be equipped with same head positioning mechanism on the relative inner wall of first arc seat 5 and second arc seat 6, head positioning mechanism is including arc protection pad 24 of difference fixed connection on the arc inner wall of first arc seat 5 and set up two recesses 25 on the arc inner wall of second arc seat 6, equal first spring 26 of fixedly connected with on the inner wall of two recesses 25, the equal fixedly connected with second dead lever 27 of one end that recess 25 inner wall was kept away from to two first springs 26, the equal fixedly connected with arc buffer block 28 of one end that first spring 26 was kept away from to two second dead levers 27, the elastic property of first spring 26 makes second dead lever 27 drive arc buffer block 28 cooperation arc protection pad 24 and carry out the centre gripping location to patient's head, neck cushion block 19, arc protection pad 24 and arc buffer block 28 are polyurethane rubber goods, polyurethane rubber goods's arc protection pad 24 and arc buffer block 28 are used for providing the buffering protection to patient's head, avoid causing the injury to patient's head.

Be equipped with stop gear between first arc seat 5 and the second arc seat 6, stop gear is including setting up two second circular recesses 29 on first arc seat 5 and the relative lateral wall of second arc seat 6 respectively, with two second circular recesses 29 of one side be close to first arc seat 5 and the setting of both ends lateral wall about second arc seat 6 respectively, equal fixedly connected with second spring 30 on two relative second circular recesses 29's the relative inner wall, the equal fixedly connected with circular piece 31 of one end that second circular recess 29 inner wall was kept away from to a plurality of second spring 30, be equipped with same root column shape piece 32 between two relative circular pieces 31, all be equipped with annular spacing groove 33 on the annular inner wall of a plurality of second circular recesses 29, circular piece 31 slides the counterbalance contact with the annular inner wall of annular spacing groove 33, second arc seat 6 is when moving to first arc seat 5 and being close to, circular piece 31 at the both ends of column shape piece 32 moves to second circular recess 29 and compresses second spring 30 under the limiting effect of annular spacing groove 33, annular spacing groove 33 has restricted the moving range of circular piece 31, the second arc seat 6 has also been restricted simultaneously, it sets up the harm to the second arc seat head of second arc seat 6 excessively, it causes the injury to the integration.

When the device is used, when a patient with Parkinson's disease lies on the bed body 1, the head of the patient lies on the arc-shaped protection pad 24 on the first arc-shaped seat 5, on one hand, the servo motor 7 is started to drive the first gear 9 on the rotating shaft 8 to rotate, so that the first gear 9 rotates to drive the second gear 11 meshed with the first gear to rotate, the second gear 11 rotates to drive the connecting rod 10 connected with the shaft to rotate, the connecting rod 10 drives the two-way threaded rod 12 to rotate simultaneously, at the moment, the rotating two-way threaded rod 12 drives the two movable adjusting blocks 13 in threaded sleeve joint to move relatively along the strip-shaped opening 4 under the limiting action of the sliding groove 14 and the sliding block 15 until the two movable adjusting blocks 13 respectively drive the two neck cushion blocks 19 to be in contact with the neck of the patient, so that the neck 19 is stressed to drive the first fixing rod 18 to compress the hydraulic buffer 17 in the first circular groove 16, and the hydraulic buffer 17 is matched with the first fixing rod 18 to drive the two neck blocks 19 to position the neck of the patient; on the other hand starts pneumatic cylinder 23 on the fixed plate 22, make pneumatic cylinder 23 drive fly leaf 21 downstream under the limiting displacement of two spinal branch vaulting poles 20, and make fly leaf 21 drive second arc seat 6 and remove to first arc seat 5, until two arc buffer blocks 28 and patient's head contact, arc buffer block 28 atress drives first spring 26 in the second dead lever 27 compression groove 25 this moment, thereby make two arc buffer blocks 28 cooperate the arc protection pad 24 in the first arc seat 5 to carry out the centre gripping location to patient's head, polyurethane rubber products's neck cushion 19 simultaneously, arc protection pad 24 and arc buffer block 28 can provide the buffer protection to patient's neck, avoid causing the injury to patient's neck.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. The utility model provides a neck magnetic resonance imaging coil sliding positioning device for parkinson's disease, includes the bed body (1), the both sides of the bed body (1) are equipped with handrail (2), its characterized in that, the upper end that bed body (1) is close to right rear side is equipped with the driving piece, be equipped with cavity (3) in the bed body (1), be equipped with bar opening (4) on cavity (3) top surface, the right side inner wall of cavity (3) is improved level and is run through and is equipped with adjustment mechanism, the driving piece is connected with the adjustment mechanism transmission, adjustment mechanism runs through bar opening (4) and sets up, adjustment mechanism is located the outer one end of cavity (3) and is equipped with neck positioning mechanism, bed body (1) is close to the first arc seat (5) of upper end fixedly connected with of rear side, be equipped with second arc seat (6) directly over first arc seat (5), the upper end of second arc seat (6) is equipped with elevating system, be equipped with same head positioning mechanism on the relative inner wall of first arc seat (5) and second arc seat (6), be equipped with stop gear between first arc seat (5) and second arc seat (6).

2. The head and neck magnetic resonance imaging coil sliding positioning device for parkinson's disease according to claim 1, wherein the driving member comprises a servo motor (7) fixedly mounted on the bed body (1) near the upper end of the right rear side, a rotating shaft (8) is fixedly connected to a driving shaft of the servo motor (7), a first gear (9) is coaxially and fixedly connected to the rotating shaft (8), and the first gear (9) is in transmission connection with the adjusting mechanism.

3. The head and neck magnetic resonance imaging coil sliding positioning device for Parkinson's disease according to claim 2, wherein the adjusting mechanism comprises a connecting rod (10) horizontally rotating and arranged through the inner wall of the right side of the chamber (3), the connecting rod (10) is positioned at one end outside the chamber (3) and is coaxially and fixedly connected with a second gear (11), the first gear (9) is meshed with the second gear (11), the connecting rod (10) is positioned at one end inside the chamber (3) and is fixedly connected with a bidirectional threaded rod (12), one end of the bidirectional threaded rod (12) far away from the connecting rod (10) is rotatably connected with the inner wall of the left side of the chamber (3), the bidirectional threaded rod (12) is sleeved with two movable adjusting blocks (13), the lower ends of the movable adjusting blocks (13) are both slidably connected with the bottom of the chamber (3), the upper ends of the movable adjusting blocks (13) are both arranged through the strip-shaped opening (4), and the neck positioning mechanism is arranged at the upper end of the two movable adjusting blocks (13) positioned outside the strip-shaped opening (4).

4. The head and neck magnetic resonance imaging coil sliding positioning device for Parkinson's disease according to claim 3, wherein the connecting rod (10) and the bidirectional threaded rod (12) are fixed by friction welding, a sliding groove (14) is formed in the bottom of the chamber (3), two sliding blocks (15) matched with the sliding groove (14) are connected in the sliding groove (14) in a sliding manner, the upper ends of the two sliding blocks (15) are fixedly connected with the lower ends of the two movable adjusting blocks (13), and the sliding groove (14) and the strip-shaped opening (4) are arranged in equal length.

5. The head and neck magnetic resonance imaging coil sliding positioning device for Parkinson's disease according to claim 1, wherein the neck positioning mechanism comprises first circular grooves (16) arranged at the upper ends of two movable adjusting blocks (13), hydraulic buffers (17) are fixedly connected to the bottoms of the first circular grooves (16), first fixing rods (18) are fixedly connected to the upper ends of the two hydraulic buffers (17), and neck cushion blocks (19) are fixedly connected to the upper ends of the first fixing rods (18).

6. The head and neck MRI coil sliding positioning device for Parkinson's disease according to claim 5, wherein the lifting mechanism comprises a support rod (20) fixedly connected to the bed body (1) and located at the upper ends of the left and right sides of the first arc-shaped seat (5), and a movable plate (21) fixedly connected to the upper end of the first arc-shaped seat (5), the upper ends of the two support rods (20) vertically penetrate through the movable plate (21), the upper ends of the two support rods (20) are fixedly connected with the same fixed plate (22), the upper end of the fixed plate (22) located at the central position is fixedly provided with a hydraulic cylinder (23), and the lower end of the piston rod of the hydraulic cylinder (23) vertically penetrates through the fixed plate (22) and is fixedly connected with the upper end of the movable plate (21) located at the central position.

7. The head and neck MRI coil sliding positioning device for Parkinson's disease according to claim 6, wherein the head positioning mechanism comprises an arc-shaped protection pad (24) fixedly connected to the arc-shaped inner wall of the first arc-shaped seat (5) and two grooves (25) arranged on the arc-shaped inner wall of the second arc-shaped seat (6), respectively, the inner walls of the two grooves (25) are fixedly connected with first springs (26), the ends of the two first springs (26) far away from the inner walls of the grooves (25) are fixedly connected with second fixing rods (27), and the ends of the two second fixing rods (27) far away from the first springs (26) are fixedly connected with arc-shaped buffer blocks (28).

8. The head and neck MRI coil sliding positioning device for Parkinson's disease according to claim 7, wherein the neck cushion block (19), the arc-shaped protection pad (24) and the arc-shaped buffer block (28) are all made of polyurethane rubber.

9. The head and neck magnetic resonance imaging coil sliding positioning device for the Parkinson's disease according to claim 1, wherein the limiting mechanism comprises two second circular grooves (29) respectively arranged on opposite side walls of a first arc-shaped seat (5) and a second arc-shaped seat (6), the two second circular grooves (29) on the same side are respectively arranged near the left side wall and the right side wall of the first arc-shaped seat (5) and the second arc-shaped seat (6), two opposite inner walls of the second circular grooves (29) are respectively and fixedly connected with second springs (30), one ends, far away from the inner walls of the second circular grooves (29), of the second springs (30) are respectively and fixedly connected with circular blocks (31), the two opposite circular blocks (31) are provided with the same cylindrical block (32), annular limiting grooves (33) are respectively arranged on the annular inner walls of the second circular grooves (29), the circular blocks (31) are in sliding contact with the annular inner walls of the annular limiting grooves (33), and the circular blocks (31) and the cylindrical blocks (32) are integrally formed.