Device for sharpening engraving tools

Abstract

The present application relates to the technical field of tool grinding equipment, improves the problem of unstable quality control of existing engraving tools during the grinding process, and discloses a device for grinding engraving tools, which includes a grinding equipment body, the grinding equipment body includes a grinding wheel; and also includes a tool block detachably connected to the grinding equipment body; a receiving cavity is provided on the tool block, and the tool can be tilted at an angle to the plane where the grinding wheel is located after entering the receiving cavity; and a first limit assembly is provided on the tool block for limiting the workpiece from continuing to move after entering the receiving cavity. The present application can realize the angle tilt adjustment between the tool and the grinding wheel without manual hand-holding, improves the grinding accuracy and consistency, and thus significantly improves the yield rate.

Description

Technical Field

[0001] The present application relates to the technical field of tool grinding equipment, and in particular to a device for grinding engraving tools. Background Art

[0002] Tool grinding equipment is a kind of equipment specially used for trimming, polishing and grinding the edge of tools. It is widely used in mechanical processing, mold manufacturing, metal processing and other industries. Because the operation process requires precise operation or the knife needs to be inserted at a specific angle. Therefore, the tools used for engraving are often precise and highly customized.

[0003] There is a tool grinder in the prior art, which includes the following main parts: a power source, which usually uses an electric motor as the power source, and drives the grinding tool to work through the rotation of the electric motor or air motor. Grinding tools include grinding wheels, grinding belts, grinding heads, etc. These tools are selected according to the grinding requirements and the material of the tool. Grinding wheels and grinding heads are usually used for coarse grinding and fine grinding, while grinding belts are more suitable for polishing. The transmission mechanism transmits the rotational power of the power source to the grinding tool to realize the rotation or reciprocating motion of the grinding tool. The control system includes power control, speed regulation, safety protection and other functions. It can achieve precise control of the grinding process and improve grinding efficiency and safety.

[0004] In the above-mentioned related technologies, during the operation, the operator needs to hold the tool body and move it relative to the grinding wheel to grind the tool according to the inclination angle of the tool. However, this method is highly dependent on the operator's experience. Insufficient experience will lead to a low tool grinding yield rate or even damage to the tool. Summary of the invention

[0005] In order to improve the problem of unstable quality control of existing engraving tools during the grinding process, the present application provides a device for grinding engraving tools.

[0006] The following technical solutions are adopted: A device for grinding an engraving tool comprises a grinding device body, wherein the grinding device body comprises a grinding wheel; and further comprises a tool block detachably connected to the grinding device body; the tool block is provided with a receiving cavity, and after the tool enters the receiving cavity, it can be inclined at an angle to the plane where the grinding wheel is located; and the tool block is provided with a first limit component for limiting the workpiece from continuing to move after entering the receiving cavity.

[0007] By adopting the above technical solution, the device is connected to the main body of the grinding equipment through a tooling block that can be detachably connected. After the tool enters the accommodating cavity of the tooling block, its position naturally forms an inclination angle with the plane of the grinding wheel, realizing the angle inclination adjustment between the tool and the grinding wheel, without manual holding, reducing human errors. The grinding accuracy and consistency are improved, and the tool damage or poor grinding caused by improper manual operation is reduced, thereby significantly improving the yield rate.

[0008] Optionally, a mounting hole is provided on the tooling block, and a plurality of fixing bolts are threadedly connected to the tooling block, and ends of the fixing bolts can be inserted into the mounting hole.

[0009] By adopting the above technical solution, the mounting hole opened on the tooling block cooperates with the threaded fixing bolt to ensure that the tooling block is firmly installed on the main body of the grinding equipment. The end of the fixing bolt is inserted into the mounting hole to achieve a tight connection. The stability and reliability of the tooling block are enhanced, and tool deviation or safety accidents caused by loose tooling blocks during the grinding process are prevented, ensuring the smooth progress of the grinding operation.

[0010] Optionally, the first limiting assembly includes a limiting rod and two limiting screws; the limiting screws are distributed at both ends of the limiting rod, and the limiting screws pass through the limiting rod to connect the tooling block; the middle part of the limiting rod can abut the tool and press the tool against the inner wall of the accommodating cavity.

[0011] By adopting the above technical solution, the limit rod passes through the limit screws at both ends and connects to the tooling block, and the middle part abuts against the tool to press the tool against the inner wall of the accommodating cavity. This effectively limits the movement of the tool during the grinding process. This ensures the stable position of the tool during the grinding process, prevents the tool from shaking or deviating from the predetermined grinding path, and further improves the grinding accuracy and yield rate.

[0012] Optionally, it also includes a tooling sphere, which has a knife hole running through it along its diameter; a rotating groove for the tooling sphere to rotate is opened in the tooling block, and the rotating groove is spherical; the accommodating cavity is a conical hollow groove, and one end of the accommodating groove is connected to the rotating groove.

[0013] By adopting the above technical solution, the tool hole opened along the diameter of the tooling ball cooperates with the spherical rotating groove in the tooling block, so that the tooling ball can rotate freely in the rotating groove. At the same time, the conical accommodating cavity is connected to the rotating groove, which provides the possibility of multi-angle grinding for the tool. Through the rotation of the tooling ball, the multi-angle adjustment of the tool during the grinding process is realized, which increases the flexibility and comprehensiveness of grinding, and further improves the grinding quality and good quality of the tool.

[0014] Optionally, both ends of the limit rod are provided with sliding grooves; the surface of the tooling block is provided with an annular limit groove concentric with the accommodating cavity, and the cross-section of the limit groove is convex; a circular end block is provided at the bottom of the limit screw; one end of the limit screw and the end block are slidably connected in the limit groove, and the other end passes through the limit groove and passes through the limit rod to connect with the limit nut.

[0015] By adopting the above technical solution, the circular end block set at the bottom of the limit screw is slidably connected to the convex limit groove on the surface of the tooling block, and the other end passes through the limit rod and is connected to the limit nut. This design enables the limit screw to move along a specific trajectory in the limit groove, thereby adjusting the position of the limit rod. The stability and reliability of the limit screw are improved, ensuring that the limit rod effectively suppresses and fixes the tool. At the same time, it is also convenient for users to fine-tune the position of the limit rod as needed to meet the grinding requirements of different tools.

[0016] Optionally, a second limiting component for limiting the rotation and radial movement of the tool along the axis is provided in the tooling sphere.

[0017] Optionally, the second limiting assembly includes a plurality of clamping rods and a plurality of driving gears; a plurality of clamping grooves are arranged in the tooling sphere along a circumferential array of the tooling holes, and one end of the clamping groove is connected to the tooling hole; the clamping rod is slidably connected to the corresponding clamping groove; a first tooth is arranged on the side wall of the clamping rod, the driving gear meshes with the corresponding clamping rod, and the driving gear is rotatably connected to the tooling sphere.

[0018] By adopting the above technical solution, the self-rotation and radial movement of the tool along the axis are restricted through the mutual cooperation of the clamping rod, the driving gear, the clamping groove and other components. When the driving gear rotates, the first teeth of the meshing drive the clamping rod to slide in the clamping groove, thereby clamping the tool. The self-rotation and radial movement of the tool during the grinding process are effectively prevented, ensuring the stability and grinding accuracy of the tool. At the same time, it also provides users with more adjustment space to meet the grinding needs of different tools.

[0019] Optionally, an end sleeve is provided at one end of the tooling sphere away from the accommodating cavity; the second limiting assembly also includes a rotating sleeve, a linkage ring and a plurality of driving gears; the plurality of driving gears are coaxially connected with the plurality of driving gears; the linkage ring is rotatably connected to the tooling sphere, and the linkage ring is located on the outer peripheral side of the plurality of driving gears; the inner wall of the linkage ring is provided with second teeth, and the second teeth are meshed with the plurality of driving gears; the rotating sleeve is rotatably connected to the outside of the end sleeve, and the rotating sleeve is connected to the linkage ring.

[0020] By adopting the above technical solution, the rotating sleeve is threadedly connected to the end sleeve on the tooling ball, and is connected to the linkage ring through a linkage rod. The second teeth on the inner wall of the linkage ring mesh with the driving gear. When the rotating sleeve rotates, the driving gear and the driving gear are driven to rotate synchronously through the linkage ring. The driving gear in the second limit assembly is driven to rotate by rotating the rotating sleeve, thereby achieving the fixation and adjustment of the tool. The operation process is simplified and the work efficiency is improved.

[0021] Optionally, the rotating sleeve is threadedly connected to the end sleeve.

[0022] By adopting the above technical solution, the threaded connection between the rotating sleeve and the end sleeve ensures the stability and reliability of the connection. At the same time, the linkage rods arranged in a circumferential array at one end of the rotating sleeve slide along the linkage holes on the linkage ring, realizing the effective connection and transmission between the rotating sleeve and the linkage ring.

[0023] Optionally, a plurality of linkage rods are arranged in a circumferential array at one end of the rotating sleeve, and a plurality of linkages for the linkage rods to slide radially are provided on an outer wall of the linkage ring.

[0024] In summary, the present application includes at least one of the following beneficial effects: 1. After the tool enters the cavity of the tooling block, it forms an inclination angle with the plane of the grinding wheel, realizing the angle adjustment between the tool and the grinding wheel, without manual holding, reducing human errors. It improves the grinding accuracy and consistency, and significantly improves the yield rate.

[0025] 2. Through the rotation of the tooling sphere, the tool can be adjusted at multiple angles during the grinding process, which increases the flexibility and comprehensiveness of grinding and further improves the grinding quality and yield of the tool.

[0026] 3. The limit rod presses the tool against the inner wall of the accommodating cavity, effectively limiting the movement of the tool during the grinding process and preventing the tool from shaking or deviating from the predetermined grinding path.

[0027] 4. The driving gear in the second limit assembly is driven to rotate by rotating the rotating sleeve, thereby fixing and adjusting the tool. This simplifies the operation process and improves work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the main body of the grinding equipment; Figure 2 It is a schematic side view of the main body of the grinding equipment; Figure 3 This is a schematic diagram showing the cross-sectional structure of the tooling block of the second embodiment; Figure 4 This is a schematic diagram of the back structure of the tooling block of the second embodiment; Figure 5It is a schematic diagram of the enlarged structure at A; Figure 6 It is a schematic diagram of the cutaway structure of the tooling sphere; Figure 7 It is a schematic diagram of the enlarged structure at B; Figure 8 It is a schematic diagram of the cutaway structure of the tooling sphere; Fig. 9 It is a schematic diagram of the cutaway structure of the tooling sphere; Fig.10 This is a schematic diagram of the enlarged structure at point C.

[0029] Explanation of the accompanying drawings: 1. Grinding equipment body; 11. Grinding wheel; 2. Tool block; 21. Accommodating chamber; 22. Mounting hole; 221. Fixing bolt; 23. Rotating groove; 231. Limiting groove; 24. Yielding groove; 3. First limiting assembly; 31. Limiting rod; 311. Slide groove; 32. Limiting screw; 321. End block; 322. Limiting nut; 4. Tool ball; 41. Knife hole; 42. Clamping groove; 43. First auxiliary groove; 44. Second auxiliary groove; 45. Linking ring groove; 46. End sleeve; 5. Second limiting assembly; 51. Clamping rod; 511. First tooth; 52. Driving gear; 53. Rotating sleeve; 531. Linking rod; 54. Linking ring; 541. Linking hole; 542. Second tooth; 55. Driving gear. DETAILED DESCRIPTION

[0030] The following is combined with Figure 1 To Attachment Fig.10 This application is described in further detail.

[0031] Embodiment 1: In the prior art, the grinding of engraving tools usually requires the worker to hold the tool and adjust the angle relative to the grinding wheel 11 to grind the tool. This grinding method is overly dependent on the worker's experience and state, so the yield rate is unstable.

[0032] In order to increase the yield rate of tool grinding. Figure 1 and Figure 2 , this embodiment discloses a device for grinding engraving tools, including a grinding device body 1 for grinding the tools, the grinding device body 1 includes a grinding wheel 11 and a series of structures for driving the grinding wheel 11 to rotate, and the grinding device body 1 belongs to the prior art and will not be described in detail here. It is worth noting that the device for grinding engraving tools also includes a tooling block 2 detachably connected to the grinding device body 1, that is, a fixture for fixing the tool. An accommodating cavity 21 is provided on the tooling block 2, and after the tool enters the accommodating cavity 21, it can be inclined at an angle to the plane where the grinding wheel 11 is located. A first limit component is provided on the tooling block 2 for limiting the workpiece from continuing to move after entering the accommodating cavity 21.

[0033] In this embodiment, the accommodating cavity 21 is a hole opened in the plane where the surface of the inclined tool block 2 is located, that is, the accommodating cavity 21 is set at an angle to the mounting hole 22. The diameter of the accommodating cavity 21 is similar to the diameter of the tool body. The tool can penetrate into the accommodating cavity 21, and the tool is limited by the first limit assembly, so that the tool head and the grinding wheel 11 are set at an angle.

[0034] There are several tooling blocks 2, and the angle of the accommodating cavity 21 of each tooling block 2 is different. Therefore, the tool can be polished at different angles by replacing tooling blocks 2 with different angles. Because the angle of the accommodating cavity 21 is fixed, the polishing of the tool can be standardized, which can increase the yield rate and the processing efficiency.

[0035] Furthermore, a mounting hole 22 is formed on the tooling block 2 , and a plurality of fixing bolts 221 are threadedly connected to the tooling block 2 , and ends of the fixing bolts 221 can be inserted into the mounting hole 22 .

[0036] Furthermore, the first limiting assembly 3 includes a limiting rod 31 and two limiting screws 32. The limiting screws 32 are distributed at both ends of the limiting rod 31. The limiting screw 32 passes through the limiting rod 31 to connect the tool block 2, and a screw hole can be opened on the tool block 2, so that the limiting screw 32 passes through the limiting rod 31 and is threadedly connected to the tool block 2 to fix the limiting bolt. The middle part of the limiting rod 31 can abut the tool and press the tool against the inner wall of the accommodating chamber 21. Since the angle of the accommodating chamber 21 is fixed in this embodiment, the corresponding screw hole opening position is also relatively easy to determine, and the limiting rod 31 can more stably press the tool against the inner wall of the accommodating chamber 21.

[0037] Embodiment 2: Since in the embodiment, when grinding the tool, the tool block 2 needs to be frequently replaced according to the angle, this method is inefficient. Therefore, this embodiment discloses a tool reversing solution with more convenient operation. Further improve the tool block 2. Figure 3 and Figure 4 , wherein the accommodating cavity 21 is a conical groove. A device for grinding an engraving tool also includes a tooling sphere 4, and a tooling hole 41 is provided along the diameter of the tooling sphere 4. A rotating groove 23 for the tooling sphere 4 to rotate is provided in the tooling block 2, and the rotating groove 23 is spherical. One end of the accommodating groove is connected to the rotating groove 23. The tool can enter the accommodating groove after passing through the tooling hole 41, and the tool can rotate with the tooling sphere 4, so that the tool can adjust the angle infinitely. After reaching the appropriate angle, the tool is fixed by the first limit assembly 3.

[0038] Reference Figures 3 to 5Therefore, in this embodiment, the limiting rod 31 of the first limiting assembly 3 has a slide groove 311 at both ends, and the slide groove 311 is opened along the length direction of the limiting rod 31. The surface of the tooling block 2 is provided with an annular limiting groove 231 concentric with the accommodating cavity 21, and the cross section of the limiting groove 231 is convex. A circular end block 321 is provided at the bottom of the limiting screw 32. One end of the limiting screw 32 and the end block 321 are slidably connected in the limiting groove 231, and the other end passes through the limiting groove 231 and passes through the limiting rod 31 to connect with the limiting nut 322. After the tool is adjusted to a suitable angle with the tooling ball 4 (against the inner wall of the accommodating chamber 21), the limiting screw 32 is slid to a suitable position, and both ends of the limiting screw 32 are inserted into the corresponding slide groove 311, and the limiting rod 31 is slid until it is pressed against the tool, and the limiting nut 322 is tightened to fix the sliding limiting rod 31 and the limiting screw 32 to increase the stability of the tool during grinding. It is worth noting that the first limiting component 3 can be set on either side of the front and back of the tooling block 2. In this embodiment, in order to facilitate the display of the structure, the first limiting component 3 is set on the back.

[0039] Reference Figures 6 to 9Furthermore, a second limiting assembly 5 for limiting the rotation and radial movement of the tool along the axis is provided in the tooling sphere 4. The second limiting assembly 5 includes a plurality of clamping rods 51 and a plurality of driving gears 52. A plurality of clamping grooves 42 are arranged in a circumferential array along the tooling hole 41 in the tooling sphere 4, and one end of the clamping groove 42 is connected with the tooling hole 41. A plurality of first auxiliary grooves 43 for the driving gear 52 to rotate are also provided in the tooling sphere 4. The first auxiliary grooves 43 are connected with the clamping grooves 42. The clamping rod 51 is slidably connected in the corresponding clamping groove 42. The side wall of the clamping rod 51 is provided with a first tooth 511, and the driving gear 52 meshes with the corresponding clamping rod 51, and the driving gear 52 is rotatably connected in the tooling sphere 4. After the driving gear 52 rotates, it can drive one end of the clamping rod 51 to penetrate into the tooling groove, thereby clamping the tool from all sides to limit the rotation and radial movement of the tool. An end sleeve 46 is provided at one end of the tooling sphere 4 away from the accommodating cavity 21, and a clearance groove 24 for the end sleeve 46 to rotate is provided on the outer wall of the tooling block 2. The second limiting assembly 5 also includes a rotating sleeve 53, a linkage ring 54 and a plurality of driving gears 55 for controlling the simultaneous movement of a plurality of driving gears 52. The plurality of driving gears 55 are coaxially connected with the plurality of driving gears 52. The tooling sphere 4 is also provided with a second auxiliary groove 44 for the driving gears 55 to rotate, and the first auxiliary groove 43 and the second auxiliary groove 44 are connected. A linkage ring groove 45 for the linkage ring 54 to rotate is provided in the tooling sphere 4, so that the linkage ring 54 is rotatably connected to the tooling sphere 4. The linkage ring 54 is located on the outer peripheral side of the plurality of driving gears 55. The linkage ring groove 45 is connected with the second transmission groove, and the inner wall of the linkage ring 54 is provided with a second tooth 542, and the second tooth 542 is meshed with the plurality of driving gears 55. The rotating sleeve 53 is rotatably connected to the outer side of the end sleeve 46, and the rotating sleeve 53 is connected to the linkage ring 54. The rotating sleeve 53 is rotated to drive the linkage ring 54 to rotate, so that the plurality of driving gears 55 meshing therewith are rotated, thereby driving the plurality of driving gears 52 to rotate, and the plurality of pressing rods 51 can be driven to press against the tool or move in a direction away from the tool.

[0040] Reference Figures 6 to 9 Furthermore, in order to increase the stability of the clamping rod 51 when restricting the tool, the rotating sleeve 53 is threadedly connected to the end sleeve 46, so that the rotating sleeve 53 has a self-locking ability after rotation. Fig.10 A plurality of linkage rods 531 are arranged in a circumferential array at one end of the rotating sleeve 53, and a plurality of linkage holes 541 are provided on the outer wall of the linkage ring 54 for the linkage rods 531 to slide radially. Since the rotating sleeve 53 is threadedly connected with the end sleeve 46, after the rotating sleeve 53 rotates, the rotating sleeve 53 will move radially. Therefore, through the linkage rods 531 that can slide in the linkage holes 541, the rotating sleeve 53 can drive the linkage ring 54 to rotate and can also move relative to the linkage ring 54 to ensure the stability of the operation of the structure.

[0041] Furthermore, scales can be set on the outer wall of the tool block 2 and around the receiving groove to accurately determine the angle of the tool. Similarly, scales can be set on the outer wall of the tool sphere 4 and around the knife groove to accurately determine the rotation angle of the tool.

[0042] The implementation principle of this embodiment is: Insert the tool into the tool slot, and rotate the rotating sleeve 53 to drive a number of clamping rods 51 to abut the tool (before this process, the tool can be rotated on its own axis to adjust the tool grinding surface). After the tool is connected to the tooling sphere 4, rotate the tool to a suitable angle, and slide the limit screw 32 to a suitable position so that the limit rod 31 is pressed against the tool, and finally the limit rod 31 is fixed by the limit nut 322. Then grind the tool, and repeat the above process to adjust other angles of the tool to grind the tool in a more standardized manner. In the process of fixing the limit rod 31, the limit rod 31 can be first inserted into the limit screw 32, and the limit rod 31 can be pushed to abut the tool, and then fixed with the limit nut 322. The former method is more convenient to adjust, and the latter method is more stable to adjust.

[0043] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A device for grinding an engraving tool, comprising a grinding device body (1), wherein the grinding device body (1) comprises a grinding wheel (11); characterized in that: The tool block (2) is detachably connected to the grinding device body (1); the tool block (2) is provided with a receiving cavity (21); after the tool enters the receiving cavity (21), it can be inclined at an angle to the plane where the grinding wheel (11) is located; and the tool block (2) is provided with a first limit assembly (3) for limiting the workpiece from continuing to move after entering the receiving cavity (21).

2. The device for grinding engraving tools according to claim 1, characterized in that: The tooling block (2) is provided with a mounting hole (22), and a plurality of fixing bolts (221) are threadedly connected to the tooling block (2), and ends of the fixing bolts (221) can be inserted into the mounting hole (22).

3. The device for grinding engraving tools according to claim 1, characterized in that: The first limiting assembly (3) comprises a limiting rod (31) and two limiting screws (32); the limiting screws (32) are distributed at both ends of the limiting rod (31), and the limiting screws (32) pass through the limiting rod (31) to connect with the tooling block (2); the middle part of the limiting rod (31) can abut against the tool and press the tool against the inner wall of the accommodating cavity (21).

4. The device for grinding engraving tools according to claim 3, characterized in that: It also comprises a tooling sphere (4), the tooling sphere (4) being provided with a through-hole (41) along its diameter; a rotation groove (23) for the tooling sphere (4) to rotate is provided in the tooling block (2), the rotation groove (23) being spherical; the accommodating cavity (21) being a conical hollow groove, one end of the accommodating groove being in communication with the rotation groove (23).

5. The device for grinding engraving tools according to claim 4, characterized in that: Both ends of the limiting rod (31) are provided with a sliding groove (311); the surface of the tooling block (2) is provided with an annular limiting groove (231) which is concentric with the accommodating cavity (21), and the cross-section of the limiting groove (231) is convex; a circular end block (321) is provided at the bottom of the limiting screw (32); one end of the limiting screw (32) and the end block (321) are slidably connected in the limiting groove (231), and the other end passes through the limiting groove (231) and passes through the limiting rod (31) to be connected with the limiting nut (322).

6. The device for grinding engraving tools according to claim 4, characterized in that: A second limiting component (5) for limiting the rotation and radial movement of the tool along the axis is arranged inside the tooling sphere (4).

7. The device for grinding engraving tools according to claim 6, characterized in that: The second limiting assembly (5) comprises a plurality of abutting rods (51) and a plurality of driving gears (52); a plurality of abutting grooves (42) are arranged in a circumferential array along the through-knife hole (41) in the tooling sphere (4), one end of each abutting groove (42) is connected to the through-knife hole (41); the abutting rods (51) are slidably connected to the corresponding abutting grooves (42); a first tooth (511) is arranged on a side wall of the abutting rods (51), the driving gear (52) meshes with the corresponding abutting rods (51), and the driving gear (52) is rotatably connected to the tooling sphere (4).

8. The device for grinding engraving tools according to claim 7, characterized in that: An end sleeve (46) is provided at one end of the tooling sphere (4) away from the accommodating cavity (21); the second limit assembly (5) further comprises a rotating sleeve (53), a linkage ring (54) and a plurality of driving gears (55); the plurality of driving gears (55) are coaxially connected to the plurality of driving gears (52); the linkage ring (54) is rotatably connected to the tooling sphere (4), and the linkage ring (54) is located on the outer peripheral side of the plurality of driving gears (55); the inner wall of the linkage ring (54) is provided with second teeth (542), and the second teeth (542) mesh with the plurality of driving gears (55); the rotating sleeve (53) is rotatably connected to the outer side of the end sleeve (46), and the rotating sleeve (53) is connected to the linkage ring (54).

9. The device for grinding engraving tools according to claim 8, characterized in that: The rotating sleeve (53) is threadedly connected to the end sleeve (46).

10. The device for grinding engraving tools according to claim 9, characterized in that: A plurality of linkage rods (531) are arranged in a circumferential array at one end of the rotating sleeve (53), and a plurality of linkage holes (541) for the linkage rods (531) to slide radially are provided on the outer wall of the linkage ring (54).

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