CN211607464U

CN211607464U - Annular ring cutter

Info

Publication number: CN211607464U
Application number: CN201922503309.3U
Authority: CN
Inventors: 章泽梦; 姚鑫波; 朱华臣; 何帝葵; 徐振宇; 倪昀
Original assignee: Jinhua Polytechnic
Current assignee: Jinhua Polytechnic
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2020-10-02
Anticipated expiration: 2029-12-31

Abstract

The utility model relates to an annular cutting device, which comprises a main bracket and an auxiliary bracket which enclose a containing cavity for containing a trunk, a locking component is arranged between the main bracket and the auxiliary bracket, the locking component is used for adjusting the ring diameter of the support, the main support is provided with a tool bit component corresponding to the inner side surface of the trunk, the auxiliary support is provided with a roller corresponding to the inner side surface of the trunk, the tool bit component comprises a tool apron, a blade, a positioning wheel and a first spring piece, the tool apron is arranged on the main support in a sliding manner, this blade holder keeps having a deformation pressure to the trunk direction through first spring part, and the setting of locating wheel is in blade holder orientation trunk one end, and the quantity of blade is two, and two blade parallel arrangement respectively are in the top and the below of locating wheel, and the blade is including the cutting part that stretches out to the locating wheel direction dorsad blade holder, the utility model aims to provide an annular girdling ware of convenient operation to control cutting depth and width that can be stable.

Description

Annular ring cutter

Technical Field

The utility model relates to an agricultural equipment field, more specifically the utility model relates to an annular girdling ware that says so.

Background

Girdling refers to the practice of stripping the bark of a certain width around the branches of a plant. The method is a planting measure for promoting flower bud differentiation and improving fruit quality, the bark (phloem) is girdled, the upper branches are girdled and grow normally after a period of time as moisture and mineral substances absorbed by root systems are transported upwards along a guide pipe, but a plurality of organic substances are accumulated at the upper ends of the cuts due to the fact that the organic substances are transported downwards, and therefore expanded callus or tumor-shaped substances are formed. If the time is long, the root system can not obtain organic nutrition for a long time, and the root system can be starved. The reason is that the tree is afraid of peeling. If the girdling is not wide, the callus can connect the upper and lower barks to restore the material transportation capability after a period of time.

The girdling device adopted in the prior art comprises a blade and an operating handle, the girdling depth and width can not be well controlled in the operation process in the actual operation, a skilled operator is needed to perform girdling work on fruit trees, and the girdling device cannot be widely popularized.

SUMMERY OF THE UTILITY MODEL

To the deficiency that prior art exists, the utility model aims to provide an annular girdling ware of convenient operation to control depth of cut and width that can be stable.

The utility model is realized by the following technical proposal

An annular girdling device comprises a support and a driving part, wherein the support is used for encircling a trunk, the driving part is arranged on the support, the support comprises a main support and an auxiliary support which can be arranged in a detachable mode, the main support and the auxiliary support are enclosed into an accommodating cavity for accommodating the trunk, a locking assembly is arranged between the main support and the auxiliary support and used for adjusting the diameter of a ring of the support, a tool bit assembly is arranged on the inner side face of the main support corresponding to the trunk, rollers are arranged on the inner side face of the auxiliary support corresponding to the trunk in an opposite mode, the number of the rollers is two, the two rollers are symmetrically arranged on two sides of the tool bit assembly, the tool bit assembly comprises a tool apron, a tool blade, a positioning wheel and a first spring part, the tool apron is arranged on the main support in a sliding mode and keeps a deformation pressure towards the trunk direction through the first spring part, the positioning wheel, the blade holder is provided with the installation axle towards trunk one end, the installation axle is established to the locating wheel movable sleeve and the blade holder rotates to be connected, the quantity of blade is two, and two blades parallel arrangement are respectively in the top and the below of locating wheel, the blade includes the cutting part that the blade holder stretches out to the locating wheel direction dorsad.

As a further improvement, the main support sets up first mount pad, and this first mount pad is provided with the mounting hole that runs through the main support, the blade holder part stretches into the mounting hole and slides with first mount pad and sets up, and first spring part setting is between blade holder and first mount pad, the articulated hand (hold) that is provided with of one end of first mount pad dorsad blade holder, this hand (hold) including the cam portion of contradicting each other with the blade holder, cam portion off-centre articulates on first mount pad.

As a further improvement, the first mounting seat inner wall is provided with a slide, the tool apron is provided with a slider, the slider is connected with the slide in a sliding manner.

As a further improvement, the blade holder all sets up the spout about the locating wheel, the blade slides with the spout and sets up, the blade is provided with the adjusting part who is used for flexible adjusting blade, and this adjusting part includes telescopic link, third spring part and cardboard, the blade is connected to telescopic link one end, and the cardboard is connected to one end, the third spring part is cup jointed to the telescopic link, third spring one end is contradicted each other with the blade, and one end is contradicted each other with the cardboard in addition, the blade holder corresponds the spout and is provided with the spacing rack of arranging by a plurality of sawtooth dorsad positioning wheel side, the quantity of spacing rack is two, forms an adjusting channel who holds the cardboard in the middle of two spacing rack symmetries set up, the cardboard both sides are provided with the sawtooth with spacing rack toothing, the third spring part keeps cardboard and spacing rack toothing.

As a further improvement, the push block is arranged on the clamping plate and is fixedly connected with the clamping plate, and one end face of the push block, which faces away from the blade, is provided with anti-skidding ribs.

As a further improvement of the present invention, the driving portion is a driving handle bar provided on the main or auxiliary support, and the driving handle bar extends toward one side of the trunk.

As a further improvement of the utility model, the main support all is the arcuation with assisting the support, the main support both ends are provided with the vertical bar guide pillar that is parallel to each other, assist the support both ends be provided with vertical bar guide pillar sliding connection's go-between, the vertical bar guide pillar is provided with the spacing tooth of a plurality of who arranges along vertical bar guide pillar length direction, the locking subassembly is used for removing the locking on the spacing tooth of a plurality of.

As a further improvement of the utility model, a plurality of the limit teeth are arranged on the inner side surface of the straight guide post, the locking component comprises a hook piece matched with the limit teeth of the two straight guide posts, a connecting rod component for adjusting the hook piece and the limit teeth, a second mounting seat and a second spring piece, the connecting rod component comprises two first connecting rods respectively hinged with the two hook pieces, a second connecting rod and a connecting plate for connecting the two first connecting rods, the first connecting rod is connected with the second mounting seat in a sliding way, the first connecting rod is hinged with the end part of the hook piece, one end of the second connecting rod is hinged with the second mounting seat, the other end of the second connecting rod is hinged with the middle position of the hook piece, a button is arranged on the second mounting seat and used for pushing the connecting plate in a collision way, the second spring piece is arranged between the connecting plate and the button, and the second spring piece has deformation elasticity which is opposite to the connecting plate to the button, used for keeping the hook piece and the limit tooth clamped with each other.

The utility model has the advantages that: when using, two gyro wheels form the three strong point that surrounds the trunk with the tool bit subassembly, and the gyro wheel is contradicted with the trunk, and the blade of tool bit subassembly can play the guide effect, and through promoting the driving piece, the blade that distributes from top to bottom carries out the girdling along the trunk surface, and the tool bit subassembly passes through elastic component and support elastic connection, can adapt to the slight irregular surface in trunk surface, guarantees that blade depth of cut keeps in a stable numerical value, the utility model discloses a set up a support around the trunk to through setting up the support into detachable main support and assistance support, and be provided with adjustable locking piece, adapt to the fruit tree of different diameters, the girdling ware that this application provided goes up convenient operation wholly, and the cutting is quick, makes the girdling guarantee stable degree of depth and width.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a view showing a usage state of the present invention;

fig. 3 is a cross-sectional view of the present invention;

FIG. 4 is a schematic view of a cutter head assembly;

FIG. 5 is a cross-sectional view of the cutter head assembly.

1. A drive section; 2. a main support; 3. an auxiliary support; 4. a roller; 5. a straight guide post; 6. a connecting ring; 7. limiting teeth; a1, locking assembly; a2, hook; a3, a second mounting seat; a4, a second spring member; a5, a first link; a6, a second link; a7, connecting plates; a8, push buttons; b1, a cutter head component; b2, a tool apron; b3, a blade; b4, a positioning wheel; b5, a first spring member; b6, mounting shaft; b7, a first mounting seat; b8, mounting holes; b9, a handle; b10, cam part; b21, a slide way; b22, a slide block; b23, a chute; b24, a telescopic rod; b25, a third spring member; b26, a clamping plate; b27, a limit rack; b28, and a push block.

Detailed Description

The present invention will be described in further detail with reference to embodiments shown in the drawings.

Referring to fig. 1-5, an annular cutter comprises a support for encircling a trunk and a driving part 1 arranged on the support, the support comprises a main support 2 and an auxiliary support 3 which are detachably arranged, the main support 2 and the auxiliary support 3 enclose a containing cavity for containing the trunk, the main support 2 and the auxiliary support 3 can be arranged in a sliding way, or can be hinged at one end, the other end is arranged in a sliding way with the main support 2, a locking component a1 is arranged between the main support 2 and the auxiliary support 3, the locking component a1 is used for adjusting the annular diameter of the support, a locking component a1 can be a bolt structure, a meshing and clamping structure or a fastening nut structure in the prior art to fix the positions of the auxiliary support 3 and the main support 2, a cutter bit component b1 is arranged on the inner side face of the main support 2 corresponding to the trunk, a roller 4 is arranged on the inner side face of the auxiliary support 3 corresponding to the trunk, the roller 4 and the cutter head component b1 are oppositely arranged, the number of the roller 4 is two, the two rollers 4 are symmetrically arranged on two sides of the cutter head component b1, the contact surface of the roller 4 and the trunk is preferably provided with an anti-slip layer, the cutter head component b1 comprises a cutter seat b2, a cutter blade b3, a positioning wheel b4 and a first spring member b5, the cutter seat b2 is slidably arranged on the main support 2, the sliding direction of the cutter seat b2 extends towards the center of the accommodating cavity, the cutter seat b2 is kept to have a deformation pressure towards the trunk through the first spring member b5, the cutter blade b3 is kept to be always in contact with the trunk for cutting in use, the positioning wheel b4 is arranged at the end, facing the trunk, of the cutter seat b2, the mounting shaft b6 is arranged at the end, of the cutter seat b2 facing the trunk, the positioning wheel b6 is movably sleeved on the cutter seat b2, the positioning wheel b4 forms a triangular positioning, the number of the blades b3 is two, the two blades b3 are respectively arranged above and below the positioning wheel b4 in parallel, the blade b3 comprises a cutting part which extends out from the blade holder b2 to the positioning wheel b4, and the length of the blade b3 extending out of the positioning wheel b4 is a preset cutting length.

When using, two gyro wheels 4 and positioning wheel b4 form the three strong point of surrounding the trunk, and gyro wheel 4 contradicts with the trunk, can play the guide effect to blade b3 of cutter head subassembly b1, and through promoting the driving piece around the trunk round, the cutter head that distributes about going up and down carries out the girdling along the trunk surface, and cutter head subassembly b1 passes through elastic component and support elastic connection, can adapt to the slight irregular surface in trunk surface, guarantees that blade b3 cutting depth keeps in a stable numerical value.

As a modified embodiment, the main stand 2 is provided with a first mounting seat b7, the first mounting seat b7 is provided with a mounting hole b8 penetrating the main stand 2, the knife holder b2 and the first mounting seat b7 are arranged in a sliding manner, the first spring part b5 is arranged between the knife holder b2 and the first mounting seat b7, the first mounting seat b7 and the knife holder b2 are both provided with bosses, the first spring part b5 is abutted between the two bosses, one end of the first mounting seat b7, which is back to the knife holder b2, is hinged with a handle b9, the handle b9 includes a cam portion b10 interfering with the knife seat b2, the cam portion b10 is eccentrically hinged on the first mounting seat b7, when the tree bark cutter is used, the handle is rotated, so that the protruding side of the cam part b10 is abutted against the cutter holder b2, the cutter holder b2 is pushed to move towards the tree trunk direction and extend into the tree bark, the position of the cutter holder b2 is adjusted by arranging the handle b9, and the tree bark cutter is convenient to mount on a support.

As a modified specific embodiment, the inner wall of the first mounting seat b7 is provided with a slide way b21, the tool apron b2 is provided with a slide block b22, the slide block b22 is slidably connected with the slide way b21, preferably, the connecting part of the tool apron b2 and the first mounting seat b7 is in a column shape, the tool apron b2 is made to slide smoothly by the arrangement of the slide way b21 and the slide block b22, the direction of the blade b3 is limited, and the tool apron b2 is ensured not to rotate.

As an improved specific embodiment, the knife holder b2 is provided with sliding grooves b23 above and below the positioning wheel b4, the blade b3 is slidably arranged with the sliding groove b23, the blade b3 is provided with an adjusting assembly for telescopically adjusting the blade b3, the adjusting assembly comprises a telescopic rod b24, a third spring member b25 and a catch plate b26, one end of the telescopic rod b24 is connected with the blade b3, the other end of the telescopic rod b24 is connected with the catch plate b26, the telescopic rod b24 is sleeved with the third spring member b25, one end of the third spring is abutted against the blade b3, the other end of the third spring is abutted against the catch plate b26, the knife holder b2 is provided with a limit rack b27 which is arranged by a plurality of saw teeth corresponding to the side of the sliding groove b23 facing away from the positioning wheel b4, the number of the limit racks b27 is two, two limit racks b27 are symmetrically arranged to form an adjusting channel for accommodating the catch plate b27, two sides of the limit rack, the third spring member b25 holds the catch plate b26 in engagement with the positive stop rack b 27.

When the tree bark girdling device is used, the clamping plate b26 is disengaged from the limiting rack b27 by pressing the clamping plate b26 downwards, the clamping plate b26 is pushed to move back and forth, the blade b3 is driven to move back and forth, the blade b3 of the blade holder b2 is telescopically adjusted, the tree bark girdling requirements of different ages are met, and different depths can be cut.

As a modified specific embodiment, the snap-gauge b26 is provided with a push block b28, the push block b28 is fixedly connected with the snap-gauge b26, one end surface of the push block b28, which faces away from the blade b3, is provided with an anti-skid convex pattern, and the push block b28 provides a force application point, so that the friction force of the force application point is increased when the snap-gauge b26 is pushed forwards and backwards.

As a modified embodiment, the driving part 1 is a driving handle bar arranged on the main support 2 or the auxiliary support 3, the driving handle bar extends back to one side of the trunk, and when the driving part is used by a worker, the worker holds the driving handle bar to drive the support to do circular motion around the trunk, so that the driving part is labor-saving and convenient.

As an improved specific embodiment, the main support 2 and the auxiliary support 3 are both arc-shaped, two ends of the main support 2 are provided with straight guide posts 5 parallel to each other, two ends of the auxiliary support 3 are provided with connecting rings 6 slidably connected with the straight guide posts 5, the straight guide posts 5 are provided with a plurality of limiting teeth 7 arranged along the length direction of the straight guide posts 5, the locking assembly a1 is used for moving and locking on the limiting teeth 7, the locking assembly a1 can be a clamping piece engaged with the limiting teeth 7 of the two straight guide posts 5, the clamping piece is kept limited between the limiting teeth 7 through a spring piece, and the structure of the clamping piece can be an adjusting assembly of the blade b3 or other existing latch structures.

As an improved specific embodiment, a plurality of the limiting teeth 7 are arranged on the inner side surface of the straight guide post 5, the locking assembly a1 comprises a hook member a2 mutually matched with the limiting teeth 7 of the two straight guide posts 5, a connecting rod assembly for adjusting the hook member a2 to be clamped with the limiting teeth 7, a second mounting seat a3 and a second spring member a4, the connecting rod assembly comprises two first connecting rods a5 respectively hinged with the two hook members a2, a second connecting rod a6 and a connecting plate a7 for connecting the two first connecting rods a5, the first connecting rods a5 are slidably connected with the second mounting seat a3, the first connecting rods a5 are hinged with the end portions of the hook members a2, one end of the second connecting rod a6 is hinged with the second mounting seat a3, the other end is hinged with the middle position of the hook members a2, the hook members a2 and the second connecting rod a6 are arranged in a rod-like curved shape matched with the arc of the auxiliary bracket 3, and one end of the two second connecting rods a 67 6 a is arranged at the middle mounting seat 3 a3, the second mounting seat a3 is provided with a button a8, the button a8 is used for pushing the connecting plate a7 in a butting manner, the second spring member a4 is arranged between the connecting plate a7 and the button a8, the second spring member a4 has deformation elasticity opposite to the connecting plate a7 to the button a8 and is used for keeping the hook member a2 and the limiting teeth 7 clamped with each other, when the engagement limitation between the hook member a2 and the straight guide post 5 needs to be relieved, the button a8 is pressed to push the first connecting rod a5 to move, the first connecting rod a5 drives the hook member a2 to be separated from the limiting teeth 7 by taking a hinge point of the second connecting rod a6 as a support, the connecting ring 6 of the auxiliary bracket 3 and the straight guide post 5 can be adjusted in a sliding manner back and forth to adapt to trunks with different diameters, and the connecting rod assembly can simultaneously control the locking relationship between the straight guide posts 5 and the connecting rings 6 on both sides, and.

It is above only the utility model discloses a preferred embodiment, the utility model discloses a scope of protection does not only confine above-mentioned embodiment, the all belongs to the utility model discloses a technical scheme under the thinking all belongs to the utility model discloses a scope of protection. It should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

The utility model discloses a working process does: when the tree bark girdling device is used, the clamping plate b26 is disengaged from the limiting rack b27 by pressing the clamping plate b26 downwards, the clamping plate b26 is pushed to move back and forth, the blade b3 is driven to move back and forth, the blade b3 of the blade holder b2 is telescopically adjusted, the tree bark girdling requirements of different ages are met, and different depths can be cut; the button a8 is pressed to push the first connecting rod a5 to move, the first connecting rod a5 drives the hook piece a2 to disengage from the limiting tooth 7 by taking the hinge point of the second connecting rod a6 as a support, the connecting ring 6 and the straight guide post 5 of the auxiliary bracket 3 can slide back and forth to adjust to adapt to trunks with different diameters, the two rollers 4 and the positioning wheel b4 form three supporting points surrounding the trunks, the rollers 4 are abutted against the trunks, the blade b3 of the blade assembly b1 can be guided, by rotating the handle, the protruding side of the cam part b10 and the blade seat b2 are interfered with each other, the blade seat b2 is pushed to move towards the trunk direction and extend into the bark, through the push driving piece round around the trunk, the cutter head that distributes from top to bottom carries out the girdling along the trunk surface, and cutter head subassembly b1 can adapt to the slight irregular surface in trunk surface through elastic component and support elastic connection, guarantees that blade b3 depth of cut keeps in a stable numerical value.

Claims

1. An annular ring cutter which is characterized in that: comprises a bracket for encircling a trunk and a driving part (1) arranged on the bracket, the bracket comprises a main bracket (2) and an auxiliary bracket (3) which are detachably arranged, the main bracket (2) and the auxiliary bracket (3) enclose an accommodating cavity for accommodating the trunk, a locking component (a1) is arranged between the main bracket (2) and the auxiliary bracket (3), the locking component (a1) is used for adjusting the ring diameter of the bracket,

the inner side face of the main support (2) corresponding to the trunk is provided with a cutter head component (b1), the inner side face of the auxiliary support (3) corresponding to the trunk is provided with idler wheels (4), the idler wheels (4) and the cutter head component (b1) are oppositely arranged, the number of the idler wheels (4) is two, the two idler wheels (4) are symmetrically arranged on two sides of the cutter head component (b1),

the cutter head assembly (b1) comprises a cutter seat (b2), two blades (b3), a positioning wheel (b4) and a first spring part (b5), wherein the cutter seat (b2) is slidably arranged on the main bracket (2), the cutter seat (b2) is kept to have a deformation pressure in the direction towards the trunk through the first spring part (b5), the positioning wheel (b4) is arranged at one end, facing the trunk, of the cutter seat (b2), a mounting shaft (b6) is arranged at one end, facing the trunk, of the cutter seat (b2), the positioning wheel (b4) is movably sleeved with the mounting shaft (b6) and is rotatably connected with the cutter seat (b2), the number of the blades (b3) is two, the two blades (b3) are respectively arranged above and below the positioning wheel (b4) in parallel, and the blades (b3) comprise cutting parts extending out in the direction opposite to the cutter seat (b2) towards the positioning wheel (b 4).

2. The annular ring cutter of claim 1, wherein: the main support (2) is provided with a first mounting seat (b7), the first mounting seat (b7) is provided with a mounting hole (b8) penetrating through the main support (2), the cutter holder (b2) partially extends into the mounting hole (b8) and is arranged in a sliding mode with the first mounting seat (b7), a first spring piece (b5) is arranged between the cutter holder (b2) and the first mounting seat (b7), one end, opposite to the cutter holder (b2), of the first mounting seat (b7 is hinged to a handle (b9), the handle (b9) comprises a cam portion (b10) which is abutted against the cutter holder (b2), and the cam portion (b10) is eccentrically hinged to the first mounting seat (b 7).

3. The annular ring cutter of claim 2, wherein: the inner wall of the first mounting seat (b7) is provided with a slide way (b21), the tool apron (b2) is provided with a slide block (b22), and the slide block (b22) is in sliding connection with the slide way (b 21).

4. The annular ring cutter of claim 1, wherein: the knife holder (b2) is provided with sliding grooves (b23) above and below a positioning wheel (b4), the blade (b3) and the sliding groove (b23) are arranged in a sliding mode, the blade (b3) is provided with an adjusting assembly used for telescopically adjusting the blade (b3), the adjusting assembly comprises a telescopic rod (b24), a third spring piece (b25) and a clamping plate (b26), one end of the telescopic rod (b24) is connected with the blade (b 57323), one end of the telescopic rod (b3) is connected with the clamping plate (b26), the telescopic rod (b24) is sleeved with the third spring piece (b25), one end of the third spring piece (b25) is abutted against the blade (b3), the other end of the third spring piece is abutted against the clamping plate (b26), the knife holder (b2) is provided with a plurality of limiting racks (b27) which are arranged by saw teeth corresponding to the side of the positioning wheel (b4), the two limiting racks (b23) are symmetrically arranged to form a limiting channel (3687458) for accommodating the clamping plate (b26), saw teeth meshed with the limiting rack (b27) are arranged on two sides of the clamping plate (b26), and the third spring piece (b25) keeps the clamping plate (b26) meshed with the limiting rack (b 27).

5. The annular ring cutter of claim 4, wherein: the clamping plate (b26) is provided with a push block (b28), the push block (b28) is fixedly connected with the clamping plate (b26), and one end face, back to the blade (b3), of the push block (b28) is provided with an anti-skid convex pattern.

6. The annular ring cutter of claim 1, wherein: the driving part (1) is a driving hand lever arranged on the main bracket (2) or the auxiliary bracket (3), and the driving hand lever extends back to one side of the trunk.

7. An annular cutter as claimed in claim 1 or 2 or 3 or 4 or 5 or 6, wherein: the main support (2) and the auxiliary support (3) are both arc-shaped, two ends of the main support (2) are provided with straight guide posts (5) which are parallel to each other, two ends of the auxiliary support (3) are provided with connecting rings (6) which are connected with the straight guide posts (5) in a sliding manner, the straight guide posts (5) are provided with a plurality of limiting teeth (7) which are arranged along the length direction of the straight guide posts (5), and the locking assembly (a1) is used for moving and locking the limiting teeth (7).

8. The annular ring cutter of claim 7, wherein: the plurality of limiting teeth (7) are arranged on the inner side surfaces of the straight guide posts (5), the locking assembly (a1) comprises a hook piece (a2) matched with the limiting teeth (7) of the two straight guide posts (5), a connecting rod assembly for clamping the adjusting hook piece (a2) with the limiting teeth (7), a second mounting seat (a3) and a second spring piece (a4), the connecting rod assembly comprises two first connecting rods (a5) hinged with the two hook pieces (a2), a second connecting rod (a6) and a connecting plate (a7) connected with the two first connecting rods (a5), the first connecting rod (a5) is connected with the second mounting seat (a3) in a sliding mode, the first connecting rod (a5) is hinged with the end of the hook piece (a2), one end of the second connecting rod (6) is hinged with the second mounting seat (a3), the other end of the second connecting rod (a2) is hinged with the middle mounting seat, and a button 8 is arranged on the second mounting seat (a3), the button (a8) is used for pushing the connecting plate (a7) in an interference mode, the second spring piece (a4) is arranged between the connecting plate (a7) and the button (a8), and the second spring piece (a4) has deformation elastic force opposite to the connecting plate (a7) to the button (a8) and is used for keeping the hook piece (a2) and the limiting tooth (7) clamped with each other.