A chamfering device for tee pipes

Abstract

The utility model discloses a kind of chamfering devices for tee pipe, the utility model relates to tee pipe processing technical field.This tee pipe chamfering device, including workbench, the surface of workbench is equipped with positioning mechanism, the side of positioning mechanism is equipped with chip removal mechanism, the surface of workbench is equipped with chamfering mechanism, reaches the purpose that tee pipe chamfering and chip removal are carried out simultaneously, the arc groove of pressing plate and tight block surface is inlaid tee pipe appearance, effectively reduces position error, chip removal passage, which is composed of chip collection part, air inlet component, cooperation link piece, outer arm, outer shaft, can collect grinding debris in real time, avoid debris pollution workshop environment, increase cleaning difficulty, prevent debris retention tee pipe inner wall, avoid subsequent pipeline blockage or fluid pollution, grinding block and the grinding cone synchronous rotation of inner shaft end part, can simultaneously chamfering processing tee pipe interface outer wall and inner wall, and chamfering and chip removal are carried out simultaneously, improve overall processing efficiency.

Description

Technical Field

[0001] This utility model relates to the field of tee pipe processing technology, specifically a chamfering device for tee pipes. Background Technology

[0002] In pipeline system installation and processing, tee pipe chamfering refers to the cutting and grinding of the interface ends (inner wall, outer wall, or end face) of a tee pipe (a pipe connector with three interfaces used to achieve fluid diversion or merging) to remove sharp edges, burrs, or flash remaining after processing, forming a transition bevel at a specific angle. Tee pipe chamfering equipment is key to ensuring chamfering quality, improving efficiency, and reducing costs. It is also the foundation for achieving safe and environmentally friendly production and supporting the development of high-end industries.

[0003] During the chamfering process of the tee pipe, metal and plastic shavings generated by the cutting equipment will be splashed outside the equipment as the cutting tool rotates, causing pollution of the workshop environment and increasing the difficulty of cleaning. In addition, the three joints of the tee pipe and the corners of the inner wall are prone to forming debris retention areas. Metal shavings inside small-diameter tee pipes may remain for a long time, leading to pipe blockage or fluid contamination. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model achieves this through the following technical solution: a chamfering device for a tee pipe, including a worktable, a positioning mechanism mounted on the surface of the worktable, a chip removal mechanism provided on the side of the positioning mechanism, a chamfering mechanism mounted on the surface of the worktable, the positioning mechanism including a driving component, the bottom of the driving component contacting the top of the worktable, a fixing component provided at the end of the driving component, the chip removal mechanism including a chip collecting component, the chip collecting component being disposed on the top of the worktable, an air intake component mounted on the side of the chip collecting component, and the chamfering mechanism including a height adjustment component, the height adjustment component being disposed on the side of the fixing component, a grinding component being mounted at the end of the height adjustment component, the air intake component starting to operate to generate directional airflow, the airflow guiding the debris generated by subsequent processing to flow into the chip collecting component, preparing for chip removal.

[0005] Preferably, the driving component includes a drive motor, a motor base is fixedly connected to the outer surface of the drive motor, the outer surface of the motor base is fixed to the top of the worktable, and a screw is fixedly connected to the end of the drive motor.

[0006] Preferably, the fixing component includes a positioning block, the outer surface of which is fixed to the top of the worktable, a slide rod slidably connected to the inner wall of the positioning block, the inner wall of which is threadedly connected to the outer surface of the screw, a pressure plate fixedly connected to the side of the positioning block away from the drive motor, a pad slidably connected to the bottom of the pressure plate, the bottom of which is fixed to the top of the worktable, a clamping block fixedly connected to the end of the pad, and arc grooves formed on the surfaces of the pressure plate and the clamping block. The outer surface of the clamping block is fixed to the end of the slide rod. The arc grooves on the surfaces of both the pressure plate and the clamping block can be adapted to the shape of the tee pipe to achieve tight fixing.

[0007] Preferably, the chip collecting component includes a chip collecting shell, the outer surface of which is fixed to the outer surfaces of the worktable, the clamping block, and the positioning block, and the outer surface of which slides against the outer surface of the pressure plate. A circular groove is formed on the surface of the chip collecting shell, a filler block is fixedly connected to the inner wall of the chip collecting shell, a connecting pipe is fixedly connected to the inner wall of the chip collecting shell, the outer surface of the connecting pipe is fixed to the inner wall of the filler block, and a filter plate is fixedly connected to the outer surface of the filler block. The filter plate on the outer surface of the filler block can prevent chip backflow.

[0008] Preferably, the air intake component includes an air collection box, the outer surface of which is fixed to the outer surfaces of the worktable, the clamping block, and the positioning block, and the outer surface of which slides against the outer surface of the pressure plate. An insert is fixedly connected to the inner wall of the air collection box, a connecting frame is fixedly connected to the inner wall of the insert, an air intake motor is fixedly connected to the inner side of the connecting frame, a round block is fixedly connected to the end of the air intake motor, a fan blade is fixedly connected to the outer surface of the round block, and a protective frame is fixedly connected to the inner wall of the insert, which protects the fan blade.

[0009] Preferably, the height adjustment component includes a frustum, the bottom of which is fixed to the outer surface of the workbench. A hydraulic cylinder is fixedly connected to the inner wall of the frustum, and a hydraulic rod is slidably connected to the inner wall of the hydraulic cylinder. A connector is fixedly connected to the end of the hydraulic rod, and an extension arm is fixedly connected to the outer surface of the connector. The hydraulic cylinder on the inner wall drives the hydraulic rod to extend and retract.

[0010] Preferably, the grinding component includes an arc block, the outer surface of which is fixed to the end of the extended arm, a grinding motor is fixedly connected to the inner wall of the arc block, a boss is fixedly connected to the end of the grinding motor, an inner shaft is fixedly connected to the end of the boss away from the truncated cone, a grinding cone is fixedly connected to the end of the inner shaft, an outer shaft is fixedly connected to the outer surface of the grinding cone, a grinding block is fixedly connected to the outer surface of the outer shaft, the end of the outer shaft is fixed to the outer surface of the boss, a chip inlet hole is formed on the surface of the outer shaft, an airflow groove is formed on the inner wall of the boss, and the grinding block on the outer shaft and the grinding cone at the end of the inner shaft can respectively chamfer the outer wall and inner wall of the T-shaped pipe interface.

[0011] This utility model provides a chamfering device for tee pipes. It has the following beneficial effects: (i) The chamfering device for this tee pipe uses a drive motor in the positioning mechanism to rotate the screw, causing the slide bar to slide on the inner wall of the positioning block, which in turn pushes the clamping block to move towards the pressure plate. The arc groove on the surface of the pressure plate and the clamping block can tightly fit the shape of the tee pipe, achieving a stable clamping and preventing the tee pipe from shifting during processing. This structural design can be adapted to tee pipes of different specifications, effectively reducing positional errors during the chamfering process, ensuring that the transition slope angle of the tee pipe interface end is uniform and the edge is smooth, greatly improving the chamfering processing quality and providing a guarantee for the sealing and safety of subsequent pipe installation.

[0012] (ii) The chamfering device of the tee pipe uses the air intake motor of the chip removal mechanism to drive the fan blade to rotate and generate airflow. Together with the chip collection shell and connecting pipe, it can collect the splashed chips. At the same time, the air pump on the connecting part can suck away the chips generated by grinding through the chip conveying channel formed by the outward extension arm, the inner cavity of the arc block and the outer shaft. The filter plate in the chip collection shell can also prevent the chips from flowing back. This not only avoids the chip contamination of the workshop environment and the increase of cleaning difficulty, but also prevents the chips from accumulating on the inner wall of the tee pipe or at the interface, avoiding subsequent pipe blockage or fluid contamination, and ensuring the cleanliness of the production environment and the performance of the pipe.

[0013] (III) The chamfering device for the tee pipe can drive the hydraulic rod to extend and retract through the hydraulic cylinder of the height adjustment component, thereby adjusting the height of the grinding component by the extension arm. It can accurately align with the interface of the tee pipe at different positions. The grinding cone and grinding block of the grinding component can respectively chamfer the inner and outer walls of the interface. Multiple parts can be processed in one operation. Chamfering and chip removal are carried out simultaneously, eliminating the need for a separate chip removal process and shortening the processing cycle. This structural design can adapt to the different interface angles and position requirements of the tee pipe, reduce equipment adjustment time, and significantly improve the overall processing efficiency. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the structure of this utility model; Figure 3 This is a cross-sectional structural diagram of the positioning mechanism and the chip removal mechanism of this utility model; Figure 4 This is a cross-sectional structural diagram of the air intake component of this utility model; Figure 5 This is a partial cross-sectional view of the chamfering mechanism of this utility model; Figure 6 This is a partial cross-sectional structural diagram of the grinding component of this utility model; Figure 7 This is a partially enlarged structural schematic diagram of the grinding component of this utility model.

[0015] In the diagram: 1. Workbench; 2. Positioning mechanism; 21. Drive component; 211. Drive motor; 212. Motor base; 213. Screw; 22. Fixing component; 221. Positioning block; 222. Slide rod; 223. Pressure plate; 224. Tightening block; 225. Arc groove; 3. Chip removal mechanism; 31. Chip collection component; 311. Chip collection shell; 312. Circular groove; 313. Connecting pipe; 314. Filler block; 315. Filter plate; 32. Air intake component; 321. Air collection box; 322. 323. Insert; 324. Connecting frame; 325. Intake motor; 326. Round block; 327. Fan blade; 328. Protective frame; 4. Chamfering mechanism; 41. Height adjustment component; 411. Frustum; 412. Hydraulic cylinder; 413. Hydraulic rod; 414. Connecting piece; 415. Extending arm; 42. Grinding component; 421. Arc block; 422. Grinding motor; 423. Boss; 424. Outer shaft; 425. Inner shaft; 426. Grinding block; 427. Grinding cone; 428. Chip inlet. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Example 1, please refer to Figure 1 This utility model provides a chamfering device for a tee pipe, including a worktable 1. A positioning mechanism 2 is mounted on the surface of the worktable 1, and a chip removal mechanism 3 is provided on the side of the positioning mechanism 2. A chamfering mechanism 4 is mounted on the surface of the worktable 1. The positioning mechanism 2 includes a driving component 21, the bottom of which contacts the top of the worktable 1, and a fixing component 22 is provided at the end of the driving component 21. The chip removal mechanism 3 includes a chip collecting component 31, which is located on the top of the worktable 1. An air inlet component 32 is mounted on the side of the chip collecting component 31. The chamfering mechanism 4 includes a height adjustment component 41. The height adjustment component 41 is located on the side of the fixed component 22. A grinding component 42 is installed at the end of the height adjustment component 41. Since the height adjustment component 41 is located on the side of the fixed component 22, its height can be adjusted by its own structure, thereby driving the grinding component 42 installed at the end to move. This allows the processing end of the grinding component 42 to be precisely aligned with the interface position of the tee pipe that needs to be chamfered. The grinding component 42 performs chamfering processing on the interface of the tee pipe. At the same time, the chip removal mechanism 3 continues to operate. The airflow generated by the air intake component 32 continuously introduces the chips generated by grinding into the chip collection component 31, so that the chamfering processing and chip collection are carried out simultaneously.

[0018] Example 2, please refer to Figures 2 to 3 Based on Embodiment 1, this utility model provides a technical solution: the driving component 21 includes a driving motor 211, a motor base 212 is fixedly connected to the outer surface of the driving motor 211, the outer surface of the motor base 212 is fixed to the top of the workbench 1, and a screw 213 is fixedly connected to the end of the driving motor 211. The fixing component 22 includes a positioning block 221, the outer surface of the positioning block 221 is fixed to the top of the workbench 1, a slide rod 222 is slidably connected to the inner wall of the positioning block 221, the inner wall of the slide rod 222 is threadedly connected to the outer surface of the screw 213, a pressure plate 223 is fixedly connected to the side of the positioning block 221 away from the driving motor 211, a pad is slidably connected to the bottom of the pressure plate 223, and the bottom of the pad is flush with the workbench. The top of the workbench 1 is fixed, and the end of the pad is fixedly connected to the fastening block 224. The surfaces of the pressure plate 223 and the fastening block 224 are provided with arc grooves 225. The outer surface of the fastening block 224 is fixed to the end of the slide rod 222. The fixing component 22 is based on the positioning block 221. The positioning block 221 is fixed to the top of the workbench 1. The slide rod 222, which is slidably connected to its inner wall, is threadedly connected to the outer surface of the screw 213. The side of the positioning block 221 away from the drive motor 211 is fixed with the pressure plate 223. The pad, which is slidably connected to the bottom of the pressure plate 223, is also fixed to the top of the workbench 1. The fastening block 224 at the end of the pad is fixed to the end of the slide rod 222. The surfaces of the pressure plate 223 and the fastening block 224 are provided with arc grooves 225, which can be adapted to the shape of the three-way pipe to achieve tight fixation.

[0019] Example 3, please refer to Figures 4 to 7Based on embodiments 1-2, this utility model provides a technical solution: the chip collecting component 31 includes a chip collecting shell 311, the outer surface of which is fixed to the outer surfaces of the workbench 1, the clamping block 224, and the positioning block 221, and the outer surface of which slides against the outer surface of the pressure plate 223. A circular groove 312 is formed on the surface of the chip collecting shell 311. A filling block 314 is fixedly connected to the inner wall of the chip collecting shell 311, and a connecting pipe 313 is fixedly connected to the inner wall of the chip collecting shell 311. The outer surface of the connecting pipe 313 is fixed to the inner wall of the filling block 314, and a filter plate 315 is fixedly connected to the outer surface of the filling block 314. The air intake component 32 includes an air collecting box 321, the outer surface of which is fixed to the workbench 1, the clamping block 224, and the positioning block 221. The outer surface of the air collection box 321 is fixed to the outer surface of the pressure plate 223. The outer surface of the air collection box 321 slides against the outer surface of the pressure plate 223. An insert 322 is fixedly connected to the inner wall of the air collection box 321. A connecting frame 323 is fixedly connected to the inner wall of the insert 322. An intake motor 324 is fixedly connected to the inner side of the connecting frame 323. A round block 325 is fixedly connected to the end of the intake motor 324. A fan blade 326 is fixedly connected to the outer surface of the round block 325. A guard 327 is fixedly connected to the inner wall of the insert 322. The height adjustment component 41 includes a frustum 411. The bottom of the frustum 411 is fixed to the outer surface of the worktable 1. A hydraulic cylinder 412 is fixedly connected to the inner wall of the frustum 411. A hydraulic rod 413 is slidably connected to the inner wall of the hydraulic cylinder 412. A connecting piece 4 is fixedly connected to the end of the hydraulic rod 413. 14. An extension arm 415 is fixedly connected to the outer surface of the connector 414. The grinding component 42 includes an arc block 421. The outer surface of the arc block 421 is fixed to the end of the extension arm 415. A grinding motor 422 is fixedly connected to the inner wall of the arc block 421. A boss 423 is fixedly connected to the end of the grinding motor 422. An inner shaft 425 is fixedly connected to the end of the boss 423 away from the frustum 411. A grinding cone 427 is fixedly connected to the end of the inner shaft 425. An outer shaft 424 is fixedly connected to the outer surface of the grinding cone 427. A grinding block 426 is fixedly connected to the outer surface of the outer shaft 424. The end of the outer shaft 424 is fixed to the outer surface of the boss 423. A chip inlet hole 428 is provided on the surface of the outer shaft 424. An airflow groove is provided on the inner wall of the boss 423. The connecting component 414 consists of a fixed block, an air pump, and a chip collection bag. The air pump is installed on the inner wall of the fixed block and forms a chip conveying channel with the outer shaft 424 through the inner cavity of the outward extension arm 415 and the arc block 421 to collect the waste chips generated at the chamfered interface during grinding. The chip collection component 31 of the chip removal mechanism 3 is centered on the chip collection shell 311. Its outer surface is fixed to the worktable 1, the clamping block 224, and the positioning block 221, and slides with the outer surface of the pressure plate 223. The circular groove 312 on the surface of the chip collection shell 311 is used for chip entry. The filling block 314 on the inner wall fixes the connecting pipe 313. The filter plate 315 on the outer surface of the filling block 314 can prevent chip backflow. The air collection box 321 of the air intake component 32 is fixed to the worktable 1, etc. The inner wall insert 322 is equipped with the air intake motor 324 through the connecting frame 323.The fan blades 326 on the circular block 325 at the motor end generate directional airflow, while the guard 327 protects the fan blades 326. The arc block 421 of the grinding component 42 is fixed to the end of the extended arm 415. The inner wall grinding motor 422 drives the boss 423, the outer shaft 424, and the inner shaft 425 to rotate. The grinding block 426 on the outer shaft 424 and the abrasive cone 427 at the end of the inner shaft 425 can respectively chamfer the outer and inner walls of the tee pipe interface. The chip inlet hole 428 on the surface of the outer shaft 424 cooperates with the airflow groove on the inner wall of the boss 423 to collect chips.

[0020] The working principle of this chamfering device for tee pipes is described in detail below: In use, the T-connector is placed between the pressure plate 223 and the clamping block 224 of the positioning mechanism 2 on the surface of the worktable 1. The drive motor 211 in the drive component 21 is started. The drive motor 211 drives the slide rod 222 to slide on the inner wall of the positioning block 221 through the screw 213. The slide rod 222 pushes the clamping block 224 to move towards the pressure plate 223. The arc groove 225 on the surface of the pressure plate 223 and the clamping block 224 firmly clamps the T-connector. Then, the hydraulic cylinder 412 of the height adjustment component 41 drives the hydraulic rod 413 to extend and retract, which drives the connecting piece 414 and the extension arm 415 to adjust the height, so that the grinding component 42 is accurately aligned with the T-connector to be chamfered interface. During this process, the chip removal mechanism 3 and the chamfering mechanism 4 are started synchronously. The air intake motor 324 of the air intake component 32 drives the round block 325 and the fan blade 326 to rotate to generate airflow. The airflow enters the chip collection shell 311 of the chip collection component 31 through the air collection box 321. At the same time, the connecting... When the air pump on component 414 is started, a negative pressure suction is established through the chip conveying channel formed by the inner cavity of the extended arm 415, the arc block 421, and the outer shaft 424. The grinding motor 422 is also started simultaneously and drives the boss 423, the outer shaft 424, and the inner shaft 425 to rotate. The grinding block 426 on the outer shaft 424 and the abrasive cone 427 at the end of the inner shaft 425 respectively perform chamfering on the outer and inner walls of the T-connector. The chips generated during chamfering are removed in real time during the processing. Part of them enter the chip conveying channel directly through the chip inlet hole 428 on the surface of the outer shaft 424 and are quickly sucked away by the suction of the air pump. The other part is collected by the airflow generated by the fan blade 326 through the circular groove 312 and the connecting pipe 313 of the chip collection shell 311. The filter plate 315 in the chip collection shell 311 can effectively prevent the backflow of chips. After the chamfering is completed, each component is reset in sequence, thereby realizing the simultaneous completion of the chamfering and chip removal of the T-connector.

[0021] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0022] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A chamfering device for a tee pipe, comprising a workbench (1), characterized in that: A positioning mechanism (2) is installed on the surface of the workbench (1). A chip removal mechanism (3) is provided on the side of the positioning mechanism (2). A chamfering mechanism (4) is installed on the surface of the workbench (1). The positioning mechanism (2) includes a driving component (21). The bottom of the driving component (21) is in contact with the top of the workbench (1). A fixing component (22) is provided at the end of the driving component (21). The chip removal mechanism (3) includes a chip collecting component (31). The chip collecting component (31) is provided at the top of the workbench (1). An air intake component (32) is installed on the side of the chip collecting component (31). The chamfering mechanism (4) includes a height adjustment component (41). The height adjustment component (41) is provided on the side of the fixing component (22). A grinding component (42) is installed at the end of the height adjustment component (41).

2. A device for chamfering a tee pipe according to claim 1, characterized in that: The driving component (21) includes a driving motor (211), and a motor base (212) is fixedly connected to the outer surface of the driving motor (211). The outer surface of the motor base (212) is fixed to the top of the workbench (1), and a screw (213) is fixedly connected to the end of the driving motor (211).

3. A device for chamfering a tee pipe according to claim 2, characterized in that: The fixing component (22) includes a positioning block (221). The outer surface of the positioning block (221) is fixed to the top of the workbench (1). A slide rod (222) is slidably connected to the inner wall of the positioning block (221). The inner wall of the slide rod (222) is threadedly connected to the outer surface of the screw (213). A pressure plate (223) is fixedly connected to the side of the positioning block (221) away from the drive motor (211). A pad is slidably connected to the bottom of the pressure plate (223). The bottom of the pad is fixed to the top of the workbench (1). A fastening block (224) is fixedly connected to the end of the pad. An arc groove (225) is opened on the surface of the pressure plate (223) and the fastening block (224). The outer surface of the fastening block (224) is fixed to the end of the slide rod (222).

4. A device for chamfering a tee pipe according to claim 3, characterized in that: The chip collection component (31) includes a chip collection shell (311). The outer surface of the chip collection shell (311) is fixed to the outer surface of the workbench (1), the clamping block (224), and the positioning block (221). The outer surface of the chip collection shell (311) slides against the outer surface of the pressure plate (223). A circular groove (312) is provided on the surface of the chip collection shell (311). A filling block (314) is fixedly connected to the inner wall of the chip collection shell (311). A connecting pipe (313) is fixedly connected to the inner wall of the chip collection shell (311). The outer surface of the connecting pipe (313) is fixed to the inner wall of the filling block (314). A filter plate (315) is fixedly connected to the outer surface of the filling block (314).

5. A device for chamfering a tee pipe according to claim 4, characterized in that: The air intake component (32) includes an air collection box (321). The outer surface of the air collection box (321) is fixed to the outer surface of the worktable (1), the clamping block (224), and the positioning block (221). The outer surface of the air collection box (321) slides against the outer surface of the pressure plate (223). An insert (322) is fixedly connected to the inner wall of the air collection box (321). A connecting frame (323) is fixedly connected to the inner wall of the insert (322). An air intake motor (324) is fixedly connected to the inner side of the connecting frame (323). A round block (325) is fixedly connected to the end of the air intake motor (324). A fan blade (326) is fixedly connected to the outer surface of the round block (325). A protective frame (327) is fixedly connected to the inner wall of the insert (322).

6. A device for chamfering a tee pipe according to claim 1, wherein: The height adjustment component (41) includes a frustum (411), the bottom of which is fixed to the outer surface of the workbench (1). A hydraulic cylinder (412) is fixedly connected to the inner wall of the frustum (411), and a hydraulic rod (413) is slidably connected to the inner wall of the hydraulic cylinder (412). A connector (414) is fixedly connected to the end of the hydraulic rod (413), and an extension arm (415) is fixedly connected to the outer surface of the connector (414).

7. A device for chamfering a tee pipe according to claim 6, characterized in that: The grinding component (42) includes an arc block (421), the outer surface of which is fixed to the end of the extension arm (415), a grinding motor (422) is fixedly connected to the inner wall of the arc block (421), a boss (423) is fixedly connected to the end of the grinding motor (422), an inner shaft (425) is fixedly connected to the end of the boss (423) away from the truncated cone (411), a grinding cone (427) is fixedly connected to the end of the inner shaft (425), an outer shaft (424) is fixedly connected to the outer surface of the grinding cone (427), a grinding block (426) is fixedly connected to the outer surface of the outer shaft (424), the end of the outer shaft (424) is fixed to the outer surface of the boss (423), a chip inlet hole (428) is provided on the surface of the outer shaft (424), and an airflow groove is provided on the inner wall of the boss (423).

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