CN219746369U

CN219746369U - Special-shaped workpiece clamping device

Info

Publication number: CN219746369U
Application number: CN202321045571.8U
Authority: CN
Inventors: 郑束停
Original assignee: Individual
Current assignee: Individual
Priority date: 2023-05-04
Filing date: 2023-05-04
Publication date: 2023-09-26
Anticipated expiration: 2033-05-04

Abstract

The utility model discloses a special-shaped workpiece clamping device which comprises a clamp seat, a movable rod, a fixed rod and two clamping blocks, wherein the fixed rod is fixedly connected with the movable rod; the right end of the moving rod is sleeved with a pushing disc, the pushing disc is hinged with a swing rod, the left end of the swing rod is close to the moving rod, the right end of the swing rod is away from the moving rod, the right end of the connecting sleeve is provided with a diameter reducing table, the left end of the swing rod is towards the diameter reducing table, the right end of the moving rod is sleeved with an auxiliary pushing block, and the right end face of the swing rod is contacted with the left end face of the auxiliary pushing block; compared with the prior art, the workpiece clamping device has the advantages that the workpiece is directly placed between the two clamping blocks, and the workpiece with different sizes can be clamped, so that the problem that the workpiece is placed by the existing workpiece clamping device and is required to be operated for the second time and only the workpiece with a single size can be clamped is solved.

Description

Special-shaped workpiece clamping device

Technical Field

The utility model relates to the field of water heating accessory machining, in particular to a special-shaped workpiece clamping device.

Background

Most of the existing water heating accessories, such as faucet shells, valve core shells and the like, are made of metal materials, and the metal shells are required to be subjected to post-processing after being molded, and the shells are required to be clamped and fixed through clamps during the post-processing.

The existing clamping device for clamping the shell comprises a clamp seat, a moving rod and a clamping block, wherein the moving rod is horizontally arranged on the clamp seat, the end parts of the two ends of the moving rod extend out of the clamp seat, the clamping block is fixedly arranged on the end part of the first end of the moving rod, a translation air cylinder for driving the moving rod to translate and a rotating motor for driving the moving rod to rotate are arranged on the clamp seat, a connecting sleeve is tightly sleeved outside the clamp seat at the second end of the moving rod, the translation air cylinder is horizontally arranged along the horizontal direction of the moving rod, the output end of the translation air cylinder is fixedly connected with the connecting sleeve, the rotating motor is fixed on the clamp seat along the horizontal direction of the moving rod and is positioned below the translation air cylinder, an inherent driving belt pulley is sleeved on the output shaft of the rotating motor, a driven belt pulley is tightly sleeved outside the second end of the moving rod, a driving belt is wound on the driving belt pulley and the driven belt pulley, the driven belt pulley is arranged between the clamp seat and the connecting sleeve, the clamping block is provided with an outer mounting shell and an inner mounting shell arranged in the outer mounting shell, the outer mounting shell is a hollow cylindrical block and is horizontally arranged along the length direction of the moving rod, the first end of the outer mounting shell is fixed with the first end of the moving rod, the second end of the outer mounting shell is open, the side wall of the outer mounting shell is provided with a strip-shaped opening which extends along the length direction of the moving rod and is communicated with the second end face of the outer mounting shell, the strip-shaped opening is provided with two strip-shaped openings, the two strip-shaped openings are oppositely arranged, the outer side wall of the outer mounting shell is provided with a strip-shaped hole which extends along the length direction of the strip-shaped opening and is communicated with the second end face of the outer mounting shell, the inner mounting shell is provided with two half shells which are oppositely attached together, the opposite faces of the two half shells are concavely provided with accommodating cavities, the two containing concave cavities enclose a placing space penetrating through the inner mounting shell.

When the water heating accessory shell is applied, the two half shells are separated, the water heating accessory shell is placed in the accommodating concave cavity of one half shell, the other half shell is closed, the water heating accessory shell is positioned in the placing space, two ends of the water heating accessory shell in the length direction extend out of the inner mounting shell, after that, the inner mounting shell and the water heating accessory shell are sleeved in the outer mounting shell through the second end opening of the outer mounting shell, the two ends of the water heating accessory shell correspondingly extend out of the strip-shaped opening, finally, the translation cylinder is started, the translation rod translates towards the direction of the transmission belt, at the moment, the first end part of the outer mounting shell extends into the clamp seat, and the outer mounting shell can take a certain shape due to the strip-shaped hole on the outer mounting shell, so that the first end part of the outer mounting shell is clamped in the clamp seat, and the fixed mounting of the water heating accessory shell is realized.

However, this kind of clamping device, when placing the work piece need place the work piece in the inner installation shell earlier, install the inner installation shell in outer installation shell again, need adopt the secondary to place the operation, make the installation effectiveness of work piece low, and again, the space of placing of inner installation shell is fixed, can only be applicable to the work piece of a size, and the commonality is poor.

In view of the above, the present inventors have conducted intensive studies on the above problems, and have produced the present utility model.

Disclosure of Invention

The utility model aims to provide a special-shaped workpiece clamping device, which solves the problems of low installation efficiency and poor universality caused by the fact that the existing workpiece clamping device needs to adopt secondary operation for workpiece placement and can only clamp single-size workpieces.

In order to achieve the above purpose, the present utility model adopts the following technical scheme:

the special-shaped workpiece clamping device comprises a clamp seat, a movable rod and a clamping block mechanism, wherein the movable rod is horizontally arranged on the clamp seat, the end parts of the two ends of the movable rod extend out of the clamp seat, the clamping block mechanism is arranged on the end part of the first end of the movable rod, a connecting sleeve positioned outside the clamp seat is sleeved tightly on the second end of the movable rod, and a translation driving device for driving the connecting sleeve to translate along the length direction of the movable rod is arranged on the clamp seat; the method is characterized in that: the clamping block mechanism is provided with a fixed rod and clamping blocks, the fixed rod is horizontally arranged along the length of the movable rod, the second end of the fixed rod is fixedly connected with the movable rod, the two clamping blocks are arranged on the end face of the first end of the fixed rod at intervals, the end parts of the second ends of the two clamping blocks are movably hinged to the first end of the fixed rod in a mode of swinging in opposite directions and swinging in opposite directions, concave through holes communicated with the end face of the first end of the clamping block are formed in opposite faces of the two clamping blocks in a concave mode, elastic pieces for tensioning the two clamping blocks are arranged in opposite faces of the two clamping blocks, and the elastic pieces are arranged outside two sides of the concave through holes;

the first end of the movable rod is taken as the left end, the second end of the movable rod is taken as the right end, a pushing disc is sleeved outside the right end of the movable rod, a swing rod extending along the left-right direction is movably hinged on the pushing disc, the left end of the swing rod is close to the movable rod, the right end of the swing rod is away from the movable rod, the right end part of the connecting sleeve is provided with a diameter reducing table which is gradually reduced from left to right, the left end part of the swing rod faces the right end of the diameter reducing table, an auxiliary pushing block positioned outside the right side of the pushing disc is sleeved outside the right end of the movable rod, and the right end face of the swing rod is contacted with the left end face of the auxiliary pushing block.

The clamp splice is two half shells that two vertical relative settings are for two half shells, and two half shells all have right fixed part and are in the outer left clamp part of right fixed part left side, and two right fixed parts enclose into the round platform that is from left to right gradually reduces, the left surface of dead lever is concavely equipped with along the embedded recess that runs through the vertical direction of dead lever to the extending direction of embedded recess is the upper and lower direction, is equipped with the articulated pole in the embedded recess, and the articulated pole is equipped with two, and two articulated poles set up at the interval from top to bottom, and the right side of two right fixed parts is protruding to be equipped with the articulated piece that sets up with articulated pole alignment to the right side, the articulated piece is on the right side of round platform, and two left clamp parts are enclosed into one by left to right gradually reducing horn structure relatively at the interval, and above-mentioned concave through hole runs through two left clamp parts along left and right direction and leads to right on the left end of right fixed part, is equipped with the horizontal through hole that is linked to with concave through hole and leads to outside on the opposite face that is in concave through hole on two right fixed part.

The elastic piece is arranged outside the concave through hole on the opposite surface of the right fixing part, two compression springs are arranged on the elastic piece, the two compression springs are respectively arranged on the right end of the right fixing part, the upper end of each compression spring is connected with the right fixing part on the upper side, and the lower end of each compression spring is fixedly connected with the right fixing part on the lower side.

The pushing disc is of a hollow cylindrical structure, a plurality of grooves are concavely formed in the left side face of the pushing disc to the right, the grooves are uniformly arranged at intervals along the circumferential direction of the pushing disc, rotating rods are arranged in the grooves, and the swing rods are hinged to the rotating rods.

The swing rod is provided with a left inclined section and a right horizontal straight section, the left inclined section extends from the outer side wall of the pushing disc to the outer side wall of the moving rod, the left inclined section is convexly provided with a convex block towards the direction of the pushing disc, the convex block is hinged with the rotating rod, and the right horizontal straight section is horizontally arranged outside the outer side wall of the pushing disc and is positioned on the right side of the left inclined section.

The connecting sleeve is provided with a left embedded section, a connecting section and a right necking section, the left embedded section and the connecting section are of hollow cylindrical structures, the connecting section is positioned on the right side of the left embedded section, the outer diameter of the connecting section is larger than that of the left embedded section, the left embedded section is positioned in the clamp seat, the right necking section is positioned on the right side of the connecting section, the right necking section is of a hollow round platform structure which is gradually reduced from left to right, and the right necking section is of the diameter reducing platform.

The right end of the right transverse straight section is provided with an arc-shaped protruding block in a protruding mode to the right, the auxiliary pushing block is of a circular plate body structure, the left side face of the auxiliary pushing block is a protruding arc face protruding to the left, and one side, close to the moving rod, of the arc-shaped protruding block is in contact with the protruding arc face.

The right end of the moving rod is sleeved with a limiting disc between the connecting sleeve and the pushing disc, an embedding opening is concavely formed in the position, located in the left inclined section, of the outer side wall of the limiting disc towards the moving rod, and the left end part of the left inclined section is located outside the left side of the limiting disc.

The utility model discloses a special-shaped work piece clamping device, when using, put into the concave through mouth of two clamp splice with the work piece, the rethread adapter sleeve moves right, the lateral wall of reducing platform and the left side mutual contact of pendulum rod, the adapter sleeve constantly outwards pushes away the pendulum rod at the right side lateral wall of reducing platform in the removal in-process that moves right, make the left side of pendulum rod deviate from the movable rod, the right side of pendulum rod then is close to the movable rod more this moment, the right side of pendulum rod then contacts with supplementary push block, the pendulum rod also constantly promotes supplementary push block, and drive the movable rod and remove, the movable rod moves right after, the right-hand member of two clamp splice falls into the anchor clamps seat and is pressed from both sides tightly, thereby realize that the work piece presss from both sides in concave through mouth, simultaneously can not receive the destruction of the clamping force of two clamp splice when making the work piece by the centre gripping under the effect of elastic component. Compared with the prior art, the workpiece clamping device has the advantages that the workpiece can be directly placed between the two clamping blocks, and workpieces with different sizes can be clamped, so that the problems that the installation efficiency is low and the universality is poor due to the fact that the existing workpiece clamping device needs to adopt secondary operation to place the workpiece and only one workpiece with a single size can be clamped are solved.

Drawings

Fig. 1 is a schematic structural view of the present utility model.

Detailed Description

For further explanation of the technical scheme of the present utility model, the following is described in detail with reference to the accompanying drawings.

The utility model relates to a special-shaped workpiece clamping device, which comprises a clamp seat (not shown in the figure), a movable rod 1 and a clamping block mechanism, wherein the movable rod 1 is horizontally arranged on the clamp seat, the two end parts of the movable rod 1 extend out of the clamp seat, the clamping block mechanism is arranged on the first end part of the movable rod 1, a connecting sleeve 2 arranged outside the clamp seat is sleeved outside the second end of the movable rod 1, a translation driving device (not shown in the figure) for driving the connecting sleeve 2 to translate along the length direction of the movable rod 1 is arranged on the clamp seat, the translation driving device is provided with a translation cylinder, the output end of the translation cylinder is fixedly connected with the connecting sleeve 2, the first end of the movable rod 1 is left, the second end of the movable rod is right, and when the special-shaped workpiece clamping device is applied, the translation driving device drives the connecting sleeve 2 to translate left and right on the movable rod.

The clamping block mechanism is provided with a fixed rod 3 and clamping blocks 4, the fixed rod 3 is horizontally arranged along the length of the movable rod 1, the second end of the fixed rod 3 is fixedly connected with the movable rod 1, the clamping blocks 4 are provided with two clamping blocks, the two clamping blocks 4 are positioned on the end face of the first end of the fixed rod 3 at intervals, the second end parts of the two clamping blocks 4 are movably hinged to the first end of the fixed rod 3 in a mode of being capable of swinging in opposite directions and swinging in opposite directions, and concave through holes 100 communicated with the end face of the first end of the clamping block 4 are concavely formed in opposite faces of the two clamping blocks 4; specifically, the two clamping blocks are two half shells which are vertically and oppositely arranged, the two half shells are provided with a right fixing part 41 and a left clamping part 42 which is positioned outside the left side of the right fixing part 41, the two right fixing parts 41 are surrounded by a conical platform which is gradually reduced from left to right, the left side surface of the fixing rod 3 is concavely provided with an embedded groove 200 which penetrates through the vertical direction of the fixing rod 3 to the right, the embedded groove 200 is internally provided with a hinging rod 31 which is arranged in the extending direction of the embedded groove 200, the hinging rod 31 is provided with two hinging rods 31 which are vertically arranged at intervals, the right side of the two right fixing parts 41 is convexly provided with a hinging block 411 which is arranged opposite to the hinging rod 31 to the right side of the two right fixing parts 41, the hinging block 411 is positioned on the right side of the right fixing part 41, the two left clamping parts 42 are oppositely arranged at intervals and are surrounded by a horn structure which is gradually reduced from left to right, the concave through opening 100 penetrates through the two left clamping parts 42 along the left and right direction to the left end of the right fixing part 41, the opposite upper opposite surfaces of the two right fixing parts 41 are provided with a front side or rear side of the concave through opening 100 which is arranged opposite to the front side of the concave opening 100 and the opposite sides of the opposite front side of the concave opening 100 and the opposite side opening 100 is communicated with the front opening 100; in application, the two clamping blocks 4 move back on the hinging rod 32 through the two hinging parts 411, and workpieces are placed in the concave through holes 100 between the two clamping blocks 4, and the arrangement of the transverse through holes enables different workpieces to have a space for preventing.

Elastic pieces 5 for tensioning the two clamping blocks 4 are arranged on opposite surfaces of the two clamping blocks 4, and the elastic pieces 5 are arranged outside two sides of the concave through hole 100; specifically, the elastic member 5 is arranged outside the concave through hole 100 on opposite surfaces of the two right fixing portions 41, two compression springs are arranged on the elastic member 5, the two compression springs are respectively arranged on the right ends of the right fixing portions 41, the upper ends of the compression springs are connected with the right fixing portions 41 on the upper side, and the lower ends of the compression springs are fixedly connected with the right fixing portions 41 on the lower side; when the clamping device is applied, when the two clamping blocks 4 move relatively to clamp a workpiece, the workpiece is clamped under the action of the elastic piece, and meanwhile, the clamping of the workpiece by the two clamping blocks cannot generate excessive hard force, so that the workpiece is prevented from being damaged at the clamping position.

The right end of the movable rod 1 is movably sleeved with a pushing disc 6, the pushing disc 6 is movably hinged with a swing rod 7 extending along the left-right direction, the left end of the swing rod 7 is close to the movable rod 1, the right end of the swing rod 7 deviates from the movable rod 1, the right end part of the connecting sleeve 2 is provided with a diameter reducing table which is gradually reduced from left to right, the left end part of the swing rod 7 faces the right end of the diameter reducing table, the right end of the movable rod 1 is sleeved with an auxiliary pushing block 8 which is positioned outside the right side of the pushing disc 6, and the right end surface of the swing rod 7 is contacted with the left end surface of the auxiliary pushing block 8; specifically, the pushing disc 6 is in a hollow cylindrical structure, a plurality of grooves are concavely arranged on the left side surface of the pushing disc 6 to the right, the grooves are uniformly arranged at intervals along the circumferential direction of the pushing disc 6, rotating rods 61 are arranged in the grooves, each rotating rod 61 is horizontally arranged in each groove along the circumferential direction of the pushing disc 6, swinging rods 7 are hinged on the rotating rods 61, the swinging rods are preferably provided with three swinging rods 7, each swinging rod 7 is provided with a left inclined section 71 and a right horizontal section 72, the left inclined section 71 extends from the outer side wall of the pushing disc 6 to the outer side wall of the moving rod 1, a bump 711 is convexly arranged on the left inclined section 71 towards the pushing disc 6, the bump is hinged with the rotating rod 61, the left end part of the left inclined section 71 is in an arc structure, the connecting sleeve 2 is provided with a left embedded section 21, a connecting section 22 and a right necking section 23, the left embedded section 21 and the connecting section 22 are in a hollow cylindrical structure, the connecting section 22 is positioned on the right side of the left embedded section 21, the outer diameter of the connecting section 22 is larger than that of the left embedded section 21, the left embedded section 21 is positioned in the clamp seat, the right necking section 23 is positioned on the right side of the connecting section 22, the right necking section 23 is of a hollow round table structure which gradually tapers from left to right, the right necking section 23 is a diameter reducing table, the left end part of the left inclined section 71 is contacted with the necking table, the right horizontal straight section 72 is horizontally arranged outside the outer side wall of the pushing disc 6 and positioned on the right side of the left inclined section 71, the right end of the right horizontal straight section 72 is provided with an arc-shaped lug 721 in a protruding manner to the right, the left side surface of the auxiliary pushing block 8 is of a circular plate body structure, one side, close to the moving rod 1, of the arc-shaped lug 721 is contacted with the convex arc-shaped surface, namely the left end bottom surface of the arc-shaped lug 721 is contacted with the convex arc-shaped surface; when the connecting sleeve 2 moves rightwards in application, each left inclined section 71 deviates from the moving rod, each right straight section 72 is close to the moving rod, the rightmost end part of each arc-shaped protruding block 721 is close to the moving rod to push the auxiliary pushing block rightwards, so that the moving rod moves rightwards, and the diameter reduction table of the connecting sleeve 2 is matched with the arc shape of the protruding block 711 to enable the connecting sleeve 2 to push rightwards more smoothly.

The utility model relates to a special-shaped workpiece clamping device, when using, put into the concave through-hole 100 of two clamp splice with the work piece, then drive translation cylinder, translation cylinder drives adapter sleeve 2 and moves rightwards, the lateral wall of reducing platform and each left inclined section 71 contact each other, and each left inclined section 71 is constantly outwards pushed away from the movable rod, make each left inclined section 71 deviate from the movable rod, the right side of right horizontal straight section 72 is close to the movable rod this moment more, and make the arc lug 721 of right horizontal straight section 72 constantly promote assist push block 8, and drive the movable rod and remove, thereby make the extreme tip of arc lug 721 contact with assist push block 8, and then make the stroke that assist push block 8 moved rightwards more, after movable rod 1 moves rightwards, two clamp splice 4 fall into the anchor clamps seat and are pressed from both sides tightly, thereby realize the clamp of work piece, and make the work piece can not receive the destruction of the clamping force of two clamp splice under the effect of elastic component. Compared with the prior art, the workpiece clamping device has the advantages that the workpiece is directly placed between the two clamping blocks 4, and workpieces with different sizes can be clamped, so that the problems that the installation efficiency is low and the universality is poor due to the fact that the existing workpiece clamping device needs to adopt secondary operation for placing the workpiece, and only workpieces with single size can be clamped are solved.

In the present utility model, it is preferable that a limiting disc 9 is sleeved between the connecting sleeve 2 and the pushing disc 6 on the right end of the moving rod 1, an embedding port is concavely provided on the outer side wall of the limiting disc 9 at the position of the left inclined section 71 toward the moving rod 1, and the left end of the left inclined section 71 is located outside the left side of the limiting disc 9; when the swing rod is used, each left inclined section 71 is positioned in each embedded opening range, so that the swing rod 7 can be limited in the embedded opening range, and the swing rod is not easy to swing up and down.

The form of the present utility model is not limited to the illustrations and examples, and any person who performs a similar idea of the present utility model should be regarded as not departing from the scope of the patent of the utility model.

Claims

1. The special-shaped workpiece clamping device comprises a clamp seat, a movable rod and a clamping block mechanism, wherein the movable rod is horizontally arranged on the clamp seat, the end parts of the two ends of the movable rod extend out of the clamp seat, the clamping block mechanism is arranged on the end part of the first end of the movable rod, a connecting sleeve positioned outside the clamp seat is sleeved tightly on the second end of the movable rod, and a translation driving device for driving the connecting sleeve to translate along the length direction of the movable rod is arranged on the clamp seat; the method is characterized in that: the clamping block mechanism is provided with a fixed rod and clamping blocks, the fixed rod is horizontally arranged along the length of the movable rod, the second end of the fixed rod is fixedly connected with the movable rod, the two clamping blocks are arranged on the end face of the first end of the fixed rod at intervals, the end parts of the second ends of the two clamping blocks are movably hinged to the first end of the fixed rod in a mode of swinging in opposite directions and swinging in opposite directions, concave through holes communicated with the end face of the first end of the clamping block are formed in opposite faces of the two clamping blocks in a concave mode, elastic pieces for tensioning the two clamping blocks are arranged in opposite faces of the two clamping blocks, and the elastic pieces are arranged outside two sides of the concave through holes;

2. The special-shaped workpiece clamping device according to claim 1, wherein the clamping blocks are two half shells which are vertically and oppositely arranged, the two half shells are provided with right fixing parts and left clamping parts which are arranged outside the left sides of the right fixing parts, round tables which are gradually reduced from left to right are enclosed by the two right fixing parts, the left side surfaces of the fixing rods are concavely provided with embedded grooves which penetrate through the vertical directions of the fixing rods to the right, the extending directions of the embedded grooves are taken as the up-down directions, the embedded grooves are internally provided with hinging rods, the hinging rods are provided with two hinging rods which are vertically arranged at intervals, the right sides of the two right fixing parts are convexly provided with hinging blocks which are oppositely arranged with the hinging rods, the hinging blocks are arranged on the right sides of the round tables, a horn structure which is gradually reduced from left to right is enclosed by the two left clamping parts, the concave through holes penetrate through the two left clamping parts to right sides along the left ends of the right fixing parts, and the front sides or the rear sides of the opposite surfaces of the two right fixing parts are concavely provided with two transverse through holes which are communicated with the concave through holes to the outside the fixing parts.

3. The special-shaped workpiece clamping device according to claim 2, wherein the elastic piece is arranged outside the concave opening on the opposite surfaces of the two right fixing parts, the elastic piece is provided with two compression springs, the two compression springs are respectively arranged on the right ends of the right fixing parts, the upper ends of the compression springs are connected with the right fixing parts on the upper sides, and the lower ends of the compression springs are fixedly connected with the right fixing parts on the lower sides.

4. The special-shaped workpiece clamping device according to claim 1, wherein the pushing disc is of a hollow cylindrical structure, a plurality of grooves are concavely formed in the left side face of the pushing disc to the right, the grooves are uniformly arranged at intervals along the circumferential direction of the pushing disc, rotating rods are arranged in the grooves, and the swing rods are hinged to the rotating rods.

5. The special-shaped workpiece clamping device according to claim 4, wherein the swing rod is provided with a left inclined section and a right transverse straight section, the left inclined section extends from the outer side wall of the pushing disc to the outer side wall of the moving rod, the left inclined section is convexly provided with a convex block towards the pushing disc, the convex block is hinged with the rotating rod, and the right transverse straight section is horizontally arranged outside the outer side wall of the pushing disc and is positioned on the right side of the left inclined section.

6. The special-shaped workpiece clamping device according to claim 5, wherein the connecting sleeve is provided with a left embedded section, a connecting section and a right necking section, the left embedded section and the connecting section are of hollow cylindrical structures, the connecting section is positioned on the right side of the left embedded section, the outer diameter of the connecting section is larger than that of the left embedded section, the left embedded section is positioned in the clamp seat, the right necking section is positioned on the right side of the connecting section, the right necking section is of a hollow round table structure which is gradually reduced from left to right, and the right necking section is of the diameter reducing table.

7. The special-shaped workpiece clamping device of claim 5, wherein the right end of the right transverse straight section is provided with an arc-shaped protruding block in a protruding mode to the right, the auxiliary pushing block is of a circular plate body structure, the left side face of the auxiliary pushing block is a protruding arc face protruding to the left, and one side, close to the moving rod, of the arc-shaped protruding block is in contact with the protruding arc face.

8. The special-shaped workpiece clamping device according to claim 5, wherein a limiting disc is sleeved between the connecting sleeve and the pushing disc on the right end of the moving rod, an embedding opening is concavely formed in the position, located on the left inclined section, of the outer side wall of the limiting disc towards the moving rod, and the left end part of the left inclined section is located outside the left side of the limiting disc.