CN114473578A - Self-locking elastic clamping device capable of freely combining with rotation - Google Patents

Abstract

The invention discloses a self-locking elastic clamping device capable of freely combining and rotating. The device comprises a rotating plate, an installation plate and a flat square shaft, wherein the flat square shaft is fixed at the bottom of the rotating plate, the installation plate is positioned below the rotating plate, an installation hole is formed in the installation plate, and the flat square shaft is rotatably connected in the installation hole through a bearing; the two ends of the rotating plate are provided with symmetrically arranged bent components, the outer end faces of the bent components are connected with cam supports, cams are rotationally connected in the cam supports, sliding channels are arranged in the bent components, square clamping sliders are slidably connected in the sliding channels, one ends of the square clamping sliders are in contact with the cams, V-groove clamping sliders which are telescopically connected with the square clamping sliders are arranged at the other ends of the square clamping sliders, and V-shaped grooves are formed in the inner side faces of the V-groove clamping sliders, so that a workpiece can be clamped and positioned accurately and quickly, assembly line operation can be performed, manpower resources are saved, the working efficiency is improved, the device is safe and reliable, and the device is convenient to disassemble and assemble during maintenance.

Description

Self-locking elastic clamping device capable of freely combining with rotation

Technical Field

The invention relates to the technical field of clamps, in particular to a self-locking elastic clamping device capable of freely combining and rotating.

Background

The jig is a device for fixing a processing object to occupy a correct position for receiving construction or inspection in a machine manufacturing process. In a broad sense, any device used to quickly, conveniently and safely mount a workpiece at any stage in a process may be referred to as a jig. In the prior art, workpieces are often clamped and fixed by a common clamp, a locking handle needs to be manually operated, a plurality of workpieces cannot be clamped simultaneously for line production, and the defects that the efficiency is low, and the workpieces cannot be clamped and positioned accurately and quickly exist. Therefore, it is necessary to provide a self-locking elastic clamping device capable of freely combining rotation to solve the above problems.

Disclosure of Invention

The invention aims to overcome the defects and provide a self-locking elastic clamping device capable of freely combining with rotation so as to solve the problems that the conventional common clamp is low in operating efficiency and cannot accurately and quickly clamp and position a workpiece.

The invention provides a self-locking elastic clamping device capable of freely combining and rotating, which comprises: the mounting plate is positioned below the rotating plate, mounting holes are formed in the mounting plate, and the flat square shaft is rotatably connected into the mounting holes through bearings; the rotary plate and the flat square shaft are internally provided with steel ball mounting grooves which are communicated, a positioning spring and steel balls are sequentially arranged in the steel ball mounting grooves from top to bottom, the steel balls can move up and down along the steel ball mounting grooves, and the upper surface of the mounting plate is provided with a pit which is opposite to the steel balls; the two ends of the rotating plate are provided with symmetrically arranged bent components, the outer end faces of the bent components are connected with cam supports, cams are rotationally connected in the cam supports, sliding channels are arranged in the bent components, square clamping sliders are slidably connected in the sliding channels, and retaining springs are arranged between the square clamping sliders and the bent components; one end of the square clamping slide block is in contact with the cam, the other end of the square clamping slide block is provided with a V-groove clamping slide block which is telescopically connected with the square clamping slide block, a clamping spring is arranged between the V-groove clamping slide block and the square clamping slide block, and the inner side end face of the V-groove clamping slide block is provided with a V-groove.

Further, the lower extreme of flat square shaft is flat square form, the bearing below is provided with first lock cap, first lock cap connect in flat square shaft outside.

Further, the self-locking elastic clamping device capable of freely combining and rotating further comprises: and the upper end of the slotted connecting sleeve is provided with a through groove matched with the shape of the lower end of the flat square shaft.

Furthermore, an adjusting screw for adjusting the pressure of the positioning spring is arranged on the rotating plate corresponding to the upper part of the positioning spring.

Furthermore, the crutch-shaped component is U-shaped, the cam bracket is n-shaped, a cover plate is arranged on the crutch-shaped component, the cam is rotatably connected in a hole in the cam bracket through a shaft pin, and the end part of the shaft pin extends out of the outer side of the cam bracket and is connected with a second locking cap.

Further, the cam faces towards one end of the square clamping slider is provided with a short diameter surface and a long diameter surface which form an alpha angle with each other, the short diameter surface and the long diameter surface are planes, the length of the short diameter surface is smaller than that of the long diameter surface, alpha is smaller than 120 degrees and is smaller than 170 degrees, the distances from the short diameter surface and the long diameter surface to the rotation center of the cam are unequal, and the rotation center of the cam reaches the vertical feet of the short diameter surface and the long diameter surface and fall into the short diameter surface and the long diameter surface respectively.

Furthermore, push rods are respectively arranged above and below the cam, and the tail ends of the push rods are 3/4 cylindrical outer circumferential surfaces.

Furthermore, an upper boss and a lower boss are formed on the cut end faces of the V-shaped groove clamping sliding block, the end faces of the upper boss and the lower boss are planes, and the extension length of the end face of the lower boss is larger than that of the end face of the upper boss.

Furthermore, a cylindrical part is arranged at the outer side end part of the V-groove clamping slide block, an installation cavity is arranged on the inner side end surface of the square clamping slide block corresponding to the cylindrical part, and a through groove penetrating through two sides of the installation cavity is arranged in the square clamping slide block; the cylinder portion of the V-groove clamping sliding block is arranged in the installation cavity, first pins are arranged on two sides of the cylinder portion of the V-groove clamping sliding block and penetrate through the through grooves, and the clamping spring is sleeved on the cylinder portion.

Furthermore, one end of the square clamping slider facing the cam is provided with an extension plate extending towards two sides, a second pin is arranged on the extension plate, and the holding spring is sleeved on the second pin.

The invention has the following beneficial effects: the self-locking elastic clamping device capable of freely combining with rotation can accurately and quickly clamp and position a workpiece, can perform assembly line operation, saves human resources, improves the working efficiency, is safe and reliable, and is convenient to disassemble and assemble during equipment maintenance.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a perspective view of a freely combined rotary self-locking elastic clamping device provided by the invention.

Fig. 2 is a schematic diagram of the freely combined and rotatable self-locking elastic clamping device and the slotted connecting sleeve provided by the invention.

Fig. 3 is a top view of the freely combined rotary self-locking elastic clamping device provided by the invention.

Fig. 4 is a sectional view taken along the line a-a of fig. 3.

Fig. 5 is a structural diagram of a square clamping slide block and a V-groove clamping slide block of the freely combined and rotated self-locking elastic clamping device provided by the invention.

Fig. 6 is a cam structure diagram of the freely combined and rotated self-locking elastic clamping device provided by the invention.

Illustration of the drawings: 1-a crutch-type member; 2-a second locking cap; 3-cover plate; 4-a retention spring; 5-axle pin; 6-flat square shaft; 7-a first locking cap; 8-a bearing; 9-steel balls; 10-mounting a plate; 11-a cam carrier; 12-a cam; 13-square clamping slide block; 14-a clamping spring; 15-V groove clamping slide block; 16-a positioning spring; 17-rotating plate; 18-grooving connecting sleeves; 151-V-shaped grooves; 152-upper boss; 153-lower boss; 154-a first pin; 131-through grooves; 132-an extension plate; 133-a second pin; 20-a push rod; 21-minor diameter surface; 22-long diameter surface.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

Spatially relative terms, such as "above … …," "above … …," "above … … surface," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Exemplary embodiments according to the present application will now be described in more detail with reference to the accompanying drawings. These exemplary embodiments may, however, be embodied in many different forms and should not be construed as limited to only the embodiments set forth herein. It is to be understood that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art, in the drawings, the thicknesses of layers and regions are exaggerated for clarity, and the same devices are denoted by the same reference numerals, and thus the description thereof will be omitted.

As shown in fig. 1 to 6, an embodiment of the present invention provides a self-locking elastic clamping device capable of freely rotating in combination, including: the locking device comprises a crutch-shaped component 1, a second locking cap 2, a cover plate 3, a retaining spring 4, a shaft pin 5, a flat square shaft 6, a first locking cap 7, a bearing 8, a steel ball 9, a mounting plate 10, a cam bracket 11, a cam 12, a square clamping slider 13, a clamping spring 14, a V-groove clamping slider 15, a positioning spring 16, a rotating plate 17 and a slotted connecting sleeve 18.

The flat square shaft 6 is fixed at the bottom of the rotating plate 17 through screws, the mounting plate 10 is positioned below the rotating plate 17, a mounting hole is formed in the mounting plate 10, and the flat square shaft 6 is rotatably connected in the mounting hole through a bearing 8. The lower extreme of flat square shaft 6 is flat square form, and 8 below of bearing are provided with first lock cap 7, and first lock cap 7 is connected in flat square shaft 6 outsidely, can play the limiting displacement to bearing 8. The upper end of the slotted connecting sleeve 18 is provided with a through groove matched with the shape of the lower end of the flat square shaft 6, when the rotating plate 17 needs to rotate, the mounting plate 10 can be driven to move by a moving mechanism on the existing equipment, so that the flat square part of the flat square shaft 6 slides into the through groove of the slotted connecting sleeve 18, and the slotted connecting sleeve 18 is fixed on a rotating shaft on the existing equipment, so that the rotating plate 17 and components on the rotating plate 17 are driven to rotate. After the operation is finished, the rotation is stopped, the flat square shaft 6 slides out of the through groove of the slotted connecting sleeve 18, and the next self-locking elastic clamping device which can freely combine with the rotation slides into the through groove of the slotted connecting sleeve 18, so that the purpose of free combination and rotation is achieved.

The rotating plate 17 and the flat square shaft 6 are internally provided with steel ball mounting grooves communicated with each other, the steel ball mounting grooves are internally provided with a positioning spring 16 and steel balls 9 from top to bottom in sequence, the steel balls 9 can move up and down along the steel ball mounting grooves, and the upper surface of the mounting plate 10 is provided with pits opposite to the steel balls 9. When the rotating plate 17 stops rotating, the steel balls 9 are pressed into the concave pits of the mounting plate 10 through the positioning springs 16, and the positioning effect is achieved. Conversely, the steel balls 9 slide out of the pits when the rotating plate 17 rotates. An adjusting screw for adjusting the pressure of the positioning spring 16 is arranged on the rotating plate 17 above the positioning spring 16, and the pressure of the positioning spring 16 is adjusted through the adjusting screw.

Two ends of the rotating plate 17 are provided with symmetrically arranged bent members 1, the outer end surfaces of the bent members 1 are connected with cam brackets 11, and the cam brackets 11 are rotatably connected with cams 12. The crank-shaped member 1 is U-shaped, and the crank-shaped member 1 is fixed on the rotating plate 17 through screws. The cam bracket 11 is shaped like a Chinese character 'ji', and the cam bracket 11 is fixed on the outer end face of the crutch component 1 through screws. The crutch component 1 is provided with a cover plate 3, and the cover plate 3 is fixed on the crutch component 1 through screws. The cam 12 is rotatably connected to the hole of the cam bracket 11 through a shaft pin 5, and the end of the shaft pin 5 extends out of the cam bracket 11 and is connected with the second locking cap 2.

A sliding channel is arranged in the crutch component 1, a square clamping slide block 13 is connected in the sliding channel in a sliding way, and a retaining spring 4 is arranged between the square clamping slide block 13 and the crutch component 1. One end of the square clamping slide block 13 is contacted with the cam 12, the other end of the square clamping slide block 13 is provided with a V-groove clamping slide block 15 which is telescopically connected with the square clamping slide block 13, a clamping spring 14 is arranged between the V-groove clamping slide block 15 and the square clamping slide block 13, and the inner side end face of the V-groove clamping slide block 15 is provided with a V-shaped groove 151.

The outer side end of the V-groove clamping slide block 15 is provided with a cylindrical part, the inner side end face of the square clamping slide block 13 is provided with a mounting cavity corresponding to the cylindrical part, and the inside of the square clamping slide block 13 is provided with through grooves 131 penetrating through two sides of the mounting cavity. The cylindrical portion of the V-groove clamping slider 15 is disposed in the mounting cavity, first pins 154 are disposed on two sides of the cylindrical portion of the V-groove clamping slider 15, the first pins 154 penetrate through the through grooves 131, the clamping spring 14 is sleeved on the cylindrical portion, and the V-groove clamping slider 15 can elastically slide in a telescopic manner relative to the square clamping slider 13. One end of the square clamping slider 13 facing the cam 12 is provided with an extending plate 132 extending towards two sides, the extending plate 132 is provided with a second pin 133, the holding spring 4 is sleeved on the second pin 133, and the square clamping slider 13 can elastically stretch and slide under the action of the cam 12. The holding spring 4 and the clamping spring 14 form an elastic structure, and the clamping device and the workpiece are not damaged when the clamping device is clamped. The V-groove clamping sliding blocks 15 on the two sides are symmetrically arranged, and the centering effect on the arch workpiece is achieved in the length direction.

In the embodiment, a short diameter surface 21 and a long diameter surface 22 which form an angle α with each other are arranged at one end of the cam 12 facing the square type clamping slider 13, the short diameter surface 21 and the long diameter surface 22 are planes, the length of the short diameter surface 21 is smaller than that of the long diameter surface 22, the angle α is less than 120 degrees and is less than 170 degrees, the distances from the short diameter surface 21 and the long diameter surface 22 to the rotation center of the cam 12 are unequal, the vertical feet from the rotation center of the cam 12 to the short diameter surface 21 and the long diameter surface 22 respectively fall in the short diameter surface 21 and the long diameter surface 22, and the design can form self-locking with the square type clamping slider 13 under the condition of adjusting the push-out distance of the square type clamping slider 13 according to the principle that the vertical line between the two points is shortest. In addition, push rods 20 are respectively arranged above and below the cam 12, and the tail ends of the push rods 20 are 3/4 cylindrical outer circumferential surfaces, so that the operation of the push rods 20 by an operator can be facilitated.

In this embodiment, the cut end surfaces of the V-groove 151 of the V-groove clamping slider 15 form an upper boss 152 and a lower boss 153, the end surfaces of the upper boss 152 and the lower boss 153 are flat surfaces, and the end surface extension length of the lower boss 153 is greater than the end surface extension length of the upper boss 152. Therefore, the workpiece bottom plate is clamped in the V-shaped groove 151 to form a gap with the lower part, so that slag can be contained, and the workpiece bottom plate can be well clamped due to deformation; the two end faces of the upper boss 152 and the lower boss 153 are formed into two faces with different heights, the end face of the lower boss 153 is formed to protrude inward a little, and the protruding length difference between the upper boss 152 and the lower boss 153 can be set to h according to the size of the bottom plate of the workpiece and the gap for placing the workpiece, so that the workpiece falls on the protruding part and does not fall on the rotating plate 17 when the workpiece is placed.

The embodiment of the invention provides a self-locking elastic clamping device capable of freely combining and rotating, when a workpiece is clamped and put in, a workpiece bottom plate falls on the lower groove surfaces of the V-shaped grooves 151 of the two V-groove clamping sliders 15, and because the lower groove surfaces of the V-groove clamping sliders 15 are protruded than the upper groove surfaces, the two V-groove clamping sliders 15 can freely slide in the square clamping sliders 13 corresponding to the lower groove surfaces. The surfaces of two sides of the square clamping slide block 13 opposite to the crutch component 1 freely slide, the crutch component 1 is made into a split type, which is convenient for processing, installation and gap adjustment, and two inner right-angle surfaces on the crutch component 1 have the function of limiting the bottom plate of the workpiece. The top surface of the square clamping slider 13 slides relative to the bottom surface of the cover plate 3. The rear part of the square clamping slide block 13 is provided with an extension plate 132, the extension plate 132 is provided with a second pin 133 for limiting the holding spring 4, and the other end of the holding spring 4 is pressed against the crutch-shaped member 1. The square type clamping slider 13 is held in contact with the cam 12 by means of the elastic force of the holding spring 4.

When a workpiece is clamped, an external force pushes the upper cylindrical surface of the upper edge of the cam 12, the cam 12 rotates in the hole of the cam bracket 11 through the small shaft pin 5, the long diameter surface of the cam 12 is gradually close to the square clamping slide block 13, the square clamping slide block 13 is pushed to move forwards by utilizing the principle of the long diameter and the short diameter of the cam, and the square clamping slide block 13 pushes the V-groove clamping slide block 15 to clamp a workpiece bottom plate through the clamping spring 14 which is in contact with the square clamping slide block 13, so that the aim of elastic clamping is fulfilled. And because the long diameter circumference surface of the cam 12 is made into a plane, and the rotation center of the cam and the vertical foot of the plane are in the plane, when the plane is matched with the square clamping slide block 13, the self-locking effect is achieved under the elastic force of the clamping spring 14.

When the workpiece is loosened, an external force pushes the cylindrical surface of the lower edge of the push rod 20 below the cam 12, the long diameter surface of the cam 12 is gradually screwed out, the short diameter surface is gradually screwed in, and the short diameter surface is a plane, and the rotating center of the cam and the perpendicular of the short diameter surface are in the short diameter surface. When the short diameter surface is completely contacted with the plane of the square clamping slide block 13, the self-locking effect is achieved. By utilizing the principle of the length and the diameter of the cam, the square clamping slide block 13 withdraws under the elasticity of the retaining spring 4, the V-groove clamping slide block 15 is provided with an anti-drop screw, the anti-drop screw is arranged in the groove of the square clamping slide block 13, the V-groove clamping slide block 15 also withdraws along with the square clamping slide block 13, the workpiece is loosened, and the loosening state is kept under the self-locking effect.

In conclusion, the self-locking elastic clamping device capable of freely combining with rotation can accurately and quickly clamp and position a workpiece, can perform assembly line operation, saves human resources, improves working efficiency, is safe and reliable, and is convenient to disassemble and assemble during equipment maintenance.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A self-locking elastic clamping device capable of freely combining and rotating is characterized by comprising: the rotary table comprises a rotary plate (17), a mounting plate (10) and a flat square shaft (6), wherein the flat square shaft (6) is fixed at the bottom of the rotary plate (17), the mounting plate (10) is positioned below the rotary plate (17), a mounting hole is formed in the mounting plate (10), and the flat square shaft (6) is rotatably connected into the mounting hole through a bearing (8);

the steel ball mounting groove is communicated with the rotating plate (17) and the flat square shaft (6), a positioning spring (16) and a steel ball (9) are sequentially arranged in the steel ball mounting groove from top to bottom, the steel ball (9) can move up and down along the steel ball mounting groove, and a pit opposite to the steel ball (9) is formed in the upper surface of the mounting plate (10);

the two ends of the rotating plate (17) are provided with symmetrically arranged bent components (1), the outer end face of each bent component (1) is connected with a cam support (11), a cam (12) is rotationally connected with the cam support (11), a sliding channel is arranged inside each bent component (1), a square clamping slide block (13) is connected in the sliding channel in a sliding mode, and a retaining spring (4) is arranged between each square clamping slide block (13) and each bent component (1); one end of the square clamping slide block (13) is in contact with the cam (12), the other end of the square clamping slide block (13) is provided with a V-groove clamping slide block (15) which is telescopically connected with the square clamping slide block (13), a clamping spring (14) is arranged between the V-groove clamping slide block (15) and the square clamping slide block (13), and the inner side end face of the V-groove clamping slide block (15) is provided with a V-shaped groove (151).

2. The freely combined and rotatable self-locking elastic clamping device according to claim 1, characterized in that the lower end of the flat square shaft (6) is flat square, a first locking cap (7) is arranged below the bearing (8), and the first locking cap (7) is connected to the outside of the flat square shaft (6).

3. The free-wheeling, self-locking, resilient clamp device of claim 2, further comprising: the upper end of the slotted connecting sleeve (18) is provided with a through groove matched with the shape of the lower end of the flat square shaft (6).

4. The freely combined rotary self-locking elastic clamping device according to claim 1, characterized in that an adjusting screw for adjusting the pressure of the positioning spring (16) is arranged on the rotating plate (17) above the positioning spring (16).

5. The freely combined and rotatable self-locking elastic clamping device according to claim 1, characterized in that the crank-shaped member (1) is U-shaped, the cam bracket (11) is n-shaped, the crank-shaped member (1) is provided with a cover plate (3), the cam (12) is rotatably connected in a hole on the cam bracket (11) through a shaft pin (5), and the end of the shaft pin (5) extends out of the cam bracket (11) and is connected with a second locking cap (2).

6. The self-locking elastic clamping device with free combination and rotation according to claim 1, wherein the end of the cam (12) facing the square clamping slider (13) is provided with a minor diameter surface (21) and a major diameter surface (22) which form an angle α with each other, the minor diameter surface (21) and the major diameter surface (22) are planes, the length of the minor diameter surface (21) is smaller than the length of the major diameter surface (22), 120 ° less than α less than 170 °, the distances from the minor diameter surface (21) and the major diameter surface (22) to the rotation center of the cam (12) are unequal, and the vertical feet from the rotation center of the cam (12) to the minor diameter surface (21) and the major diameter surface (22) fall in the minor diameter surface (21) and the major diameter surface (22) respectively.

7. The freely combined rotary self-locking elastic clamping device according to claim 1, characterized in that push rods (20) are respectively arranged above and below the cam (12), and the tail ends of the push rods (20) are 3/4 cylindrical outer circumferential surfaces.

8. The self-locking elastic clamping device capable of freely combining with rotation according to claim 1, characterized in that the cut end surfaces of the V-shaped groove (151) of the V-groove clamping slide block (15) form an upper boss (152) and a lower boss (153), the end surfaces of the upper boss (152) and the lower boss (153) are planes, and the end surface extension length of the lower boss (153) is greater than the end surface extension length of the upper boss (152).

9. The self-locking elastic clamping device capable of freely combining and rotating according to claim 1, wherein a cylindrical portion is arranged at the outer side end of the V-groove clamping sliding block (15), a mounting cavity is arranged on the inner side end face of the square clamping sliding block (13) corresponding to the cylindrical portion, and a through groove (131) penetrating through two sides of the mounting cavity is arranged inside the square clamping sliding block (13); the cylindrical portion of the V-shaped groove clamping sliding block (15) is arranged in the installation cavity, first pins (154) are arranged on two sides of the cylindrical portion of the V-shaped groove clamping sliding block (15), the first pins (154) penetrate through the through grooves (131), and the clamping spring (14) is sleeved on the cylindrical portion.

10. The freely combined and rotatable self-locking elastic clamping device as claimed in claim 1, wherein an extension plate (132) extending towards two sides is arranged at one end of the square clamping slider (13) facing the cam (12), a second pin (133) is arranged on the extension plate (132), and the retaining spring (4) is sleeved on the second pin (133).

Images