A high-stability fixture for machining the rear-end rectifier ring of an aero-engine
By combining adaptive bonding components and hydraulic components, the problem of unstable clamping of the rectifier ring was solved, achieving stable clamping and rotation, and improving the machining accuracy and efficiency of the rectifier ring.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU YUHANG AEROSPACE TECH CO LTD
- Filing Date
- 2026-04-20
- Publication Date
- 2026-05-26
AI Technical Summary
Existing fixtures are difficult to effectively and stably hold the conical surface of the aero-engine rectifier ring, and are prone to obstruction or obstruction during the machining process, affecting machining accuracy and efficiency.
Multiple adaptive bonding components and hydraulic components work together with the drive components to achieve stable clamping of the rectifier ring through a clamping force from all four sides toward the center and a lateral counterforce. The roller structure allows the rectifier ring to rotate, which facilitates surface treatment.
This achieves stable clamping and rotation of the rectifier ring, improving processing accuracy and efficiency, and enhancing product stability and the consistency of surface finish smoothness.
Smart Images
Figure CN122077535A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of machining technology, specifically to a highly stable fixture for machining the rear-end rectifier ring of an aero-engine. Background Technology
[0002] The aero-engine rectifier ring is a key "stator" component in an aero-engine, and its core task is to guide airflow and improve efficiency.
[0003] The production of aero-engine rectifier rings requires multiple processes. To ensure the precise geometry of the airflow channel, the rectifier ring must be clamped and fixed before surface treatment. When processing conical rectifier rings, the fixture, as an important auxiliary tool for machining operations, must have good stability, positioning ability, and adaptability to accommodate products of different specifications. Due to the conical structure of the rectifier ring, existing fixtures are difficult to effectively and stably clamp it while avoiding obstruction and hindrance to the rectifier ring during subsequent processing. Therefore, we propose a highly stable fixture for machining the rear-end rectifier ring of aero-engines. Summary of the Invention
[0004] The purpose of this invention is to provide a highly stable fixture for machining the rear-end rectifier ring of an aero-engine, in order to solve the problems mentioned in the background art, namely, that it is not easy to form a stable state when clamping the conical rectifier ring, and it is difficult to take into account the subsequent machining process. To achieve the above objectives, the present invention provides the following technical solution: a high-stability fixture for machining the rear-end rectifier ring of an aero-engine, comprising a fixed frame, wherein multiple extension platforms are fixedly connected to the outer ring surface of the fixed frame, a driving component is provided on one side of each extension platform, a hydraulic component is provided on one side of the driving component, and an adaptive fitting component is provided on the side of the multiple hydraulic components that are close to each other, and the adaptive fitting component clamps the rectifier ring by the force provided by the hydraulic component, wherein one of the adaptive fitting components is provided with a power component for driving the rectifier ring to rotate, and each hydraulic component consists of a clamping part and a pulling part, wherein the clamping part includes two support seats fixedly connected to one side of the extension platform, a main pipe is fixedly sleeved inside the two support seats, the main pipe passes through the two support seats, two first pistons are slidably connected inside the main pipe, a first sealing ring is fixedly sleeved on the outer wall of the first piston, the first sealing ring is slidably connected to the inner wall of the main pipe, and a first piston rod is fixedly connected to the opposite side of the two first pistons, and the opposite end of the two first piston rods movably passes through the main pipe.
[0005] More preferably, the pull-button part consists of a stage execution unit and a pull-button unit. The stage execution unit includes a branch pipe fixedly connected to the outer wall of the main pipe, the inner cavity of the branch pipe communicating with the inner cavity of the main pipe, a limit ring fixedly sleeved on the inner wall of the branch pipe near the main pipe, a second piston slidably connected to the inside of the branch pipe, a second sealing ring fixedly sleeved on the outer wall of the second piston, the second sealing ring slidably connected to the inner wall of the branch pipe, a spring abutting between the bottom of the inner cavity of the branch pipe and the second piston, an extension sleeve fixedly connected to the outer wall of the main pipe, the inner cavity of the extension sleeve communicating with the inner cavity of the main pipe, a second stopper rod fixedly connected to the side of the second piston away from the spring, and the second stopper rod sequentially penetrates the inner cavities of the main pipe and the extension sleeve, and the second stopper rod slidably connects to the inner wall of the extension sleeve.
[0006] More preferably, the pull-button unit includes an extension rod fixedly connected to one end of the second stopper rod, and the end of the extension rod away from the second stopper rod is rotatably connected to a first roller via a bearing.
[0007] More preferably, the drive assembly includes a push rod motor, one side of which is fixedly connected to a support base away from the rectifier ring, and a connecting rod is fixedly connected to the output end of the push rod motor. The connecting rod is fixedly connected to one end of a first plug rod away from the rectifier ring.
[0008] More preferably, the adaptive bonding component consists of an angle adaptive part and a bonding part, the angle adaptive part is hinged to the first plug rod, and the bonding part is adaptively bonded to the outer wall of the rectifier ring by a driving component providing force.
[0009] More preferably, the angle adaptive part includes a second hinge seat, which is hinged to one end of the first plug rod near the rectifier ring. A flip plate is fixedly connected to the side of the second hinge seat near the rectifier ring. Two fixing plates are fixedly connected to the outer edge of the main pipe near the rectifier ring. Tension springs are fixedly connected to the side of the two fixing plates opposite to the flip plate.
[0010] More preferably, the fitting part includes two first hinge seats fixedly connected to the side of the flip plate near the rectifier ring, and a second roller is rotatably connected to the opposite side of the two first hinge seats via a bearing, and the outer wall of the second roller is rotatably connected to the outer wall of the rectifier ring.
[0011] More preferably, the power assembly includes a rotating shaft fixedly connected to one end of the central shaft of the second roller, a first synchronous pulley fixedly connected to the end of the rotating shaft away from the second roller, a connecting plate fixedly connected to the side of the flipping plate near the rotating shaft, a drive motor fixedly connected to the side of the connecting plate away from the flipping plate, a second synchronous pulley fixedly connected to the output end of the drive motor, and a synchronous belt drivingly connected to the outer walls of the second synchronous pulley and the first synchronous pulley.
[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, multiple adaptive fitting components are used to center and clamp the conical rectifier ring. The clamping part and the pull-fastening part are driven one by one by the hydraulic component and the drive component to achieve clamping in two steps, thereby stably clamping the rectifier ring. The clamping part centers the rectifier ring from all sides and provides a force from all sides to the center. Since the rectifier ring is conical, it will generate forces in two directions: a force from all sides to the center and a lateral force from the constricted part to the flared part. Therefore, the pull-fastening part applies a reverse force from the flared part to the constricted part to the rectifier ring, thereby balancing the lateral force of the rectifier ring and making the rectifier ring stable after clamping.
[0013] In this invention, the first roller and the second roller enable the rectifier ring to rotate along its central axis. Driven by the power component, the rectifier ring rotates, exposing the positions previously blocked by the second roller and the first roller as the rectifier ring rotates. This facilitates overall and continuous surface treatment of the rectifier ring, thereby improving production efficiency, enhancing the consistency of surface smoothness after treatment, and ultimately improving product stability. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the three-dimensional structure of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the three-dimensional structure of the present invention. Figure 2 ; Figure 3 For the present invention Figure 2 Schematic diagram of the structure at point A in the middle; Figure 4 This is a partially enlarged structural schematic diagram of the present invention; Figure 5 This is a side view of the structure of the present invention; Figure 6 For the present invention Figure 5 Schematic diagram of the structure at point B; Figure 7 This is a schematic diagram of the cross-sectional structure of the present invention; Figure 8 This is a partial cross-sectional structural diagram of the present invention.
[0015] In the diagram: 1. Fixed frame; 2. Main pipe; 3. First piston; 4. Spring; 5. Fixed plate; 6. Rotating shaft; 7. Connecting rod; 11. Extension platform; 21. Branch pipe; 22. Extension sleeve; 23. Support seat; 31. First sealing ring; 32. First plug rod; 41. Second piston; 42. Second sealing ring; 43. Second plug rod; 44. Limiting ring; 45. Extension rod; 46. First roller; 51. Tension spring; 52. Flipping plate; 53. First hinge seat; 54. Second roller; 55. Second hinge seat; 61. First synchronous pulley; 62. Synchronous belt; 63. Second synchronous pulley; 64. Drive motor; 65. Connecting plate; 71. Push rod motor. Detailed Implementation
[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0017] Please see Figures 1-8 The present invention provides a technical solution: a high-stability fixture for machining the rear-end rectifier ring of an aero-engine, comprising a fixed frame 1, with multiple extension platforms 11 fixedly connected to the outer ring surface of the fixed frame 1, a drive component on one side of each extension platform 11, a hydraulic component on one side of the drive component, and an adaptive fitting component on the side of the multiple hydraulic components that are close to each other, and the adaptive fitting component clamps the rectifier ring by the force provided by the hydraulic component, and a power component for driving the rectifier ring to rotate is provided on one of the adaptive fitting components, each hydraulic component is composed of a clamping part and a pull-out part, the clamping part includes two support seats 23 fixedly connected to one side of the extension platform 11, a main pipe 2 is fixedly sleeved inside the two support seats 23, the main pipe 2 passes through the two support seats 23, two first pistons 3 are slidably connected inside the main pipe 2, a first sealing ring 31 is fixedly sleeved on the outer wall of the first piston 3, the first sealing ring 31 is slidably connected to the inner wall of the main pipe 2, and a first piston rod 32 is fixedly connected to the opposite side of the two first pistons 3, and the opposite ends of the two first piston rods 32 movably pass through the main pipe 2; A guide rod is fixedly connected to the outer wall of the first stop rod 32 extending from one end of the main pipe 2. A sliding sleeve that is adapted to slide the main pipe 2 is fixedly connected to the outer wall of the main pipe 2. The rotation of the first stop rod 32 is restricted by the sliding sleeve and the guide rod, so that the first stop rod 32 can only slide along the longitudinal direction of the first stop rod 32, ensuring the subsequent clamping stability. The rectifier ring has a constricted opening on the side closer to the fixed frame 1 and an flared opening on the side farther from the fixed frame 1. Multiple extension stages 11, drive components, hydraulic components, and adaptive bonding components are all arranged in a ring array around the central axis of the rectifier ring; The drive assembly drives the hydraulic assembly to cause multiple adaptive fitting components to clamp the rectifier ring; The purpose of this invention is to provide a highly stable fixture for machining the rear-end rectifier ring of an aero-engine, in order to solve the problems mentioned in the background art. The space between the two first pistons 3 is filled with hydraulic oil for transmitting force. When one of the first piston rods 32 in the main pipe 2 is driven, the hydraulic oil can be used as a transmission medium to drive the other first piston rod 32 in the main pipe 2 to move, and then the rectifier ring is clamped by the adaptive fitting component.
[0018] In this embodiment, as Figure 1 , Figure 4 and Figure 8 As shown, the pull-button part consists of a stage execution unit and a pull-button unit. The stage execution unit includes a branch pipe 21 fixedly connected to the outer wall of the main pipe 2. The inner cavity of the branch pipe 21 is connected to the inner cavity of the main pipe 2. A limit ring 44 is fixedly sleeved on the inner wall of the branch pipe 21 near the main pipe 2. A second piston 41 is slidably connected to the inside of the branch pipe 21. A second sealing ring 42 is fixedly sleeved on the outer wall of the second piston 41. The second sealing ring 42 is slidably connected to the inner wall of the branch pipe 21. A spring 4 is abutted between the bottom of the inner cavity of the branch pipe 21 and the second piston 41. An extension sleeve 22 is fixedly connected to the outer wall of the main pipe 2. The inner cavity of the extension sleeve 22 is connected to the inner cavity of the main pipe 2. A second plug rod 43 is fixedly connected to the side of the second piston 41 away from the spring 4. The second plug rod 43 passes through the inner cavities of the main pipe 2 and the extension sleeve 22 in sequence. The second plug rod 43 is slidably connected to the inner wall of the extension sleeve 22. The outer wall of the second stopper 43 and the inner wall of the extension sleeve 22 are slidably connected by a sealing ring, and the sealing ring ensures a seal. The limiting ring 44 is used to limit the stroke of the second piston 41.
[0019] In this embodiment, as Figure 1 , Figure 4 and Figure 8 As shown, the pull-button unit includes an extension rod 45 fixedly connected to one end of the second stopper rod 43, and the end of the extension rod 45 away from the second stopper rod 43 is rotatably connected to a first roller 46 via a bearing; A telescopic rod is provided between the extension rod 45 and the main pipe 2, and the two ends of the telescopic rod are fixedly connected to the outer wall of the opposite side of the extension rod 45 and the main pipe 2, respectively. The main pipe 2 and the branch pipe 21 form a three-way cavity, which is surrounded by two first pistons 3 and a second piston 41 near the second piston rod 43. The cavity is filled with hydraulic oil. When the first piston rod 32 away from the rectifier ring moves, the other first piston rod 32 and the second piston rod 43 can be driven to move synchronously through hydraulic transmission. Since the spring 4 always provides a force to bring the second piston 41 closer to the limiting ring 44, the first piston rod 32 near the rectifier ring moves closer to the rectifier ring first. Then, the reaction force provided by the adaptive fitting component after contacting the rectifier ring prevents the first piston rod 32 near the rectifier ring from continuing to move. At this time, the first piston rod 32 away from the rectifier ring continues to apply a thrust, making the force greater than the elastic force of the spring 4, so that the second piston 41 moves away from the limiting ring 44. At this time, the spring 4 is compressed, and the second piston rod 43 moves towards the branch pipe 21, finally allowing the outer wall of the first roller 46 to abut against the flared port edge of the rectifier ring.
[0020] In this embodiment, as Figure 1 , Figure 4 and Figure 8 As shown, the drive assembly includes a push rod motor 71. One side of the push rod motor 71 is fixedly connected to the support base 23 away from the rectifier ring. The output end of the push rod motor 71 is fixedly connected to a connecting rod 7. The connecting rod 7 is fixedly connected to one end of the first plug rod 32 away from the rectifier ring. The PLC control system reads the position information of each motor encoder, calculates the average position, and adjusts the speed of each motor to achieve synchronous operation of multiple push rod motors 71; the output end of the push rod motor 71 drives the first stop rod 32 fixedly connected to the connecting rod 7 to move by extending or retracting.
[0021] In this embodiment, as Figure 1 , Figure 3 and Figure 6 As shown, the adaptive bonding component consists of an angle adaptive part and a bonding part. The angle adaptive part is hinged to the first plug rod 32, and the bonding part is adaptively bonded to the outer wall of the rectifier ring by the force provided by the driving component.
[0022] In this embodiment, as Figure 1 , Figure 3 and Figure 6 As shown, the angle adaptive part includes a second hinge seat 55, which is hinged to one end of the first plug rod 32 near the rectifier ring. A flip plate 52 is fixedly connected to the side of the second hinge seat 55 near the rectifier ring. Two fixing plates 5 are fixedly connected to the outer edge of the main pipe 2 near the rectifier ring. Tension springs 51 are fixedly connected to the side of the two fixing plates 5 opposite to the flip plate 52. The two tension springs 51 are of the same specification. When they are not initially clamped on the rectifier ring, their elastic force can make the flip plate 52 and the main pipe 2 tend to be perpendicular. At the same time, the flip plate 52 is hinged to the first plug rod 32 through the second hinge seat 55, and can freely deflect within a certain range, so that the fitting part can adaptively fit rectifier rings of different sizes and angles, thereby realizing the clamping of rectifier rings of various specifications, improving the flexibility of use and the scope of application.
[0023] In this embodiment, as Figure 1 , Figure 3 and Figure 6 As shown, the fitting part includes two first hinge seats 53 fixedly connected to the side of the flip plate 52 near the rectifier ring. The opposite side of the two first hinge seats 53 is rotatably connected to a second roller 54 via a bearing. The outer wall of the second roller 54 is rotatably connected to the outer wall of the rectifier ring. Multiple second rollers 54 moving towards the center contact the outer wall of the rectifier ring, clamping the rectifier ring from multiple directions. Through the action of the angle adaptive part, the second rollers 54 are effectively fitted to the outer wall of the rectifier ring. At the same time, the pull-fastening part constrains one side of the flared position of the rectifier ring, so that the rectifier ring is positioned and clamped. Meanwhile, through the rotatable first roller 46 and second roller 54, the rectifier ring can rotate along its own central axis, which facilitates the subsequent driving of the rectifier ring to rotate and perform physical polishing treatment on its surface.
[0024] In this embodiment, as Figure 1 , Figure 3 and Figure 6 As shown, the power assembly includes a rotating shaft 6 fixedly connected to one end of the central shaft of the second roller 54. A first synchronous pulley 61 is fixedly connected to the end of the rotating shaft 6 away from the second roller 54. A connecting plate 65 is fixedly connected to the side of the flipping plate 52 near the rotating shaft 6. A drive motor 64 is fixedly connected to the side of the connecting plate 65 away from the flipping plate 52. A second synchronous pulley 63 is fixedly connected to the output end of the drive motor 64. A synchronous belt 62 is connected to the outer walls of the second synchronous pulley 63 and the first synchronous pulley 61 for transmission. The drive motor 64 provides power and drives the second roller 54 to rotate through the transmission structure. The friction generated after the second roller 54 clamps the rectifier ring can drive the rectifier ring to rotate synchronously. Then, the outer wall, inner wall and port edge of the rectifier ring are manually ground, polished and deburred by grinding tools.
[0025] The method of use and advantages of this invention: This highly stable fixture for machining the rear-end rectifier ring of an aero-engine operates as follows: First, the fixture is installed on the workbench via the base. Then, the equipment is initialized and the material is manually loaded. The rectifier ring is placed at the center of the circle formed by multiple second rollers 54. Then, multiple push rod motors 71 are started synchronously through the PLC control system. Their output ends retract, driving the first plug rod 32 near the connecting rod 7 to move into the main tube 2. The output end of the push rod motor 71 retracts inward, thereby driving the first plug rod 32 near the connecting rod 7 to move into the main pipe 2. The first piston 3 connected to it pushes the hydraulic oil synchronously, thereby pushing the first piston 3 on the other side and the corresponding first plug rod 32, so that the second roller 54 approaches the rectifier ring. Since the outer wall of the rectifier ring is conical, the second roller 54 can make adaptive angle adjustment through the hinge relationship between the second hinge seat 55 and the first plug rod 32 until all the second rollers 54 are completely in contact with the outer wall of the rectifier ring. After the multiple second rollers 54 are fully engaged with the rectifier ring, the reaction force provided by the rectifier ring prevents the first plug rod 32 near the rectifier ring from moving further. The force will overcome the force of the spring 4 to push the second piston 41, causing the second plug rod 43 to retract into the branch pipe 21. This allows the first roller 46 to abut against the port edge of the rectifier ring. The multiple second rollers 54 and the multiple first rollers 46 complete the adaptive clamping and positioning of the rectifier ring. The second rollers 54 and the first rollers 46 are rotatable, allowing the rectifier ring to rotate along its central axis. Then the drive motor 64 is started, and the second roller 54 is rotated through the power transmission of the first synchronous pulley 61, the synchronous belt 62, the second synchronous pulley 63 and the rotating shaft 6, thereby driving the rectifier ring to rotate. During the rotation of the rectifier ring, its surface can be treated by mechanical processing or manual operation.
Claims
1. A highly stable fixture for machining the rear-end rectifier ring of an aero-engine, characterized in that, The device includes a fixed frame (1), on which multiple extension platforms (11) are fixedly connected. Each extension platform (11) has a drive assembly on one side and a hydraulic assembly on one side. Adaptive fitting components are provided on the sides of the multiple hydraulic assemblies that are close to each other. The adaptive fitting components clamp the rectifier ring using the force provided by the hydraulic assemblies. One of the adaptive fitting components has a power assembly for driving the rectifier ring to rotate. Each hydraulic assembly consists of a clamping part and a pull-pull part. The clamping part includes components fixedly connected to the extension platform (11). Two support seats (23) on one side of the platform (11) are connected together to a main pipe (2). The main pipe (2) passes through the two support seats (23). Two first pistons (3) are slidably connected inside the main pipe (2). A first sealing ring (31) is fixedly fitted on the outer wall of the first piston (3). The first sealing ring (31) is slidably connected to the inner wall of the main pipe (2). A first stopper rod (32) is fixedly connected to the opposite side of the two first pistons (3). The opposite ends of the two first stopper rods (32) both movably pass through the main pipe (2).
2. The high-stability fixture for machining the rear-end rectifier ring of an aero-engine according to claim 1, characterized in that: The pull-button unit consists of a stage execution unit and a pull-button unit. The stage execution unit includes a branch pipe (21) fixedly connected to the outer wall of the main pipe (2). The inner cavity of the branch pipe (21) is connected to the inner cavity of the main pipe (2). A limit ring (44) is fixedly sleeved on the inner wall of the branch pipe (21) near the main pipe (2). A second piston (41) is slidably connected inside the branch pipe (21). A second sealing ring (42) is fixedly sleeved on the outer wall of the second piston (41). The second sealing ring (42) is connected to the branch pipe (21). 1) The inner wall of the branch pipe (21) is slidably connected. The bottom of the inner cavity of the branch pipe (21) is abutted against the second piston (41) by a spring (4). An extension sleeve (22) is fixedly connected to the outer wall of the main pipe (2). The inner cavity of the extension sleeve (22) is connected to the inner cavity of the main pipe (2). A second plug rod (43) is fixedly connected to the side of the second piston (41) away from the spring (4). The second plug rod (43) passes through the inner cavity of the main pipe (2) and the extension sleeve (22) in sequence. The second plug rod (43) is slidably connected to the inner wall of the extension sleeve (22).
3. A high-stability fixture for machining the rear-end rectifier ring of an aero-engine according to claim 2, characterized in that: The pull-button unit includes an extension rod (45) fixedly connected to one end of the second stopper rod (43), and the end of the extension rod (45) away from the second stopper rod (43) is rotatably connected to a first roller (46) via a bearing.
4. A high-stability fixture for machining the rear-end rectifier ring of an aero-engine according to claim 3, characterized in that: The drive assembly includes a push rod motor (71), one side of which is fixedly connected to a support base (23) away from the rectifier ring. A connecting rod (7) is fixedly connected to the output end of the push rod motor (71), and the connecting rod (7) is fixedly connected to one end of a first plug rod (32) away from the rectifier ring.
5. A high-stability fixture for machining the rear-end rectifier ring of an aero-engine according to claim 4, characterized in that: The adaptive bonding component consists of an angle adaptive part and a bonding part. The angle adaptive part is hinged to the first plug rod (32), and the bonding part is adaptively bonded to the outer wall of the rectifier ring by the force provided by the driving component.
6. A high-stability fixture for machining the rear-end rectifier ring of an aero-engine according to claim 5, characterized in that: The angle adaptive part includes a second hinge seat (55), which is hinged to one end of the first plug rod (32) near the rectifier ring. A flip plate (52) is fixedly connected to the side of the second hinge seat (55) near the rectifier ring. Two fixing plates (5) are fixedly connected to the outer edge of the main tube (2) near the rectifier ring. Tension springs (51) are fixedly connected to the two fixing plates (5) on the side opposite to the flip plate (52).
7. A high-stability fixture for machining the rear-end rectifier ring of an aero-engine according to claim 6, characterized in that: The fitting part includes two first hinge seats (53) fixedly connected to the side of the flip plate (52) near the rectifier ring. The two first hinge seats (53) are rotatably connected to the opposite side of the two first hinge seats (53) via bearings. The outer wall of the second roller (54) is rotatably connected to the outer wall of the rectifier ring.
8. A high-stability fixture for machining the rear-end rectifier ring of an aero-engine according to claim 7, characterized in that: The power assembly includes a rotating shaft (6) fixedly connected to one end of the central shaft of the second roller (54). A first synchronous pulley (61) is fixedly connected to the end of the rotating shaft (6) away from the second roller (54). A connecting plate (65) is fixedly connected to the side of the flipping plate (52) near the rotating shaft (6). A drive motor (64) is fixedly connected to the side of the connecting plate (65) away from the flipping plate (52). A second synchronous pulley (63) is fixedly connected to the output end of the drive motor (64). A synchronous belt (62) is connected to the outer walls of the second synchronous pulley (63) and the first synchronous pulley (61) for transmission.