Gold piece changing driving mechanism

Abstract

The utility model discloses a gold plaque changing driving mechanism. A swinging shaft rotating along with a swinging arm enters from a driving notch and is matched with a driving groove to shift a driving plate, or slides out from the driving notch to be separated from the driving groove; the positioning block enters the working position and is matched with the positioning groove, and the positioning groove is positioned at the working position. The positioning block and the positioning groove are completely mechanically matched, the motor does not need to participate when the positioning groove is positioned, the positioning block is provided with an arc-shaped outer contour concentric with the driving shaft, when the positioning block is matched with the positioning groove, the driving shaft can be allowed to deflect leftwards and rightwards, positioning of the positioning groove cannot be affected, and therefore the requirement for the stop position of the motor is lowered, and the production efficiency is improved. And the requirement on a positioning sensor can be reduced. The multi-sequin driving device is separated from the positioning machine in sliding, and the pure mechanical positioning enables the driving and positioning to be reliable and effective.

Description

Technical Field

[0001] The utility model relates to a gold sheet changing driving mechanism. Background Art

[0002] When embroidering a multi-gold piece, a driving mechanism is required to drive the film feeding device to move, so that a corresponding group of film feeders of the film feeding device can be moved to the working position to feed the film, and can cooperate with the machine needle to realize embroidery.

[0003] One of the existing driving mechanisms of the film feeding device is to connect the film feeding device and the fixed seat through a belt pulley slider assembly, the driving motor drives the pulley, the pulley drives the belt, and the belt drives the film feeding device that is slidably connected to the fixed seat through the slider. The other is to connect the film feeding device and the fixed seat through a screw nut slider assembly, the driving motor drives the screw, the rotating screw cooperates with the nut slider, and drives the film feeding device to slide through the nut slider. The above two driving mechanisms require the motor to have a high precision during the process of the motor driving the corresponding film feeding device to move, so as to drive the corresponding film feeder of the film feeding device to accurately enter the working position. After the corresponding film feeder enters the working position, the motor is also required to have an accurate stagnation ability, so as to keep the film feeder relatively stable and accurately feeding the film at the working position during the process, which increases the cost of the motor and the cost of program module control.

[0004] When the corresponding film feeder enters the working position and feeds the film, the stagnation ability of the motor requires the corresponding driver to issue instructions to the motor so that the motor is powered on and remains stable to prevent the motor from accidentally rotating forward or reverse. Since the motor is in a stagnant and non-working state, it will cause the motor to heat up after powering on, thereby increasing the motor's sluggishness and causing errors in the next action of the motor. Since the multi-gold film needs to be replaced frequently, the accumulation of errors will affect the stability of the multi-gold film feeding device. At present, there is no better way to solve the above problems. Summary of the invention

[0005] The utility model aims to solve the problems existing in the use of the existing gold sheet changing drive mechanism and provides a gold sheet changing drive mechanism which can reduce the motor requirements, reduce the cost and relatively accurately lock the sheet feeding device.

[0006] The utility model provides a technical solution to the existing problem: a sequin changing drive mechanism, comprising a seat plate, a driving motor arranged on the seat plate, a slide rail assembly connecting the seat plate and a multiple sequin device, and as an improvement, further comprising a driving assembly, wherein the driving assembly comprises a driving shaft for transmitting power of the driving motor and a driving plate connected to the multiple sequin device.

[0007] The driving plate is provided with at least two groups of positioning structures arranged along the sliding direction of the driving plate, each group of positioning structures comprises positioning grooves and driving grooves arranged along the sliding direction of the driving plate, and the positioning grooves and driving grooves are provided with inlet and outlet openings.

[0008] The driving shaft is provided with a swing arm, and the swing arm is provided with a swing shaft which enters or disengages from the driving groove as the driving shaft drives the swing arm to rotate. The swing shaft can enter the driving groove in turn as the swing arm rotates, and cooperates with the driving groove to move the driving plate to slide. The swing arm and / or the driving shaft are provided with a positioning block which cooperates with the positioning groove of the corresponding group entering the working position as the driving shaft rotates, and positions the positioning groove at the working position. The positioning block is provided with an arc-shaped outer contour which is concentric with the driving shaft and cooperates with the positioning groove. The positioning block is also provided with a disengagement portion which can be disengaged from the cooperation with the positioning groove. The disengagement portion and the arc-shaped outer contour form a positioning block. The positioning block disengages from or disengages from the cooperation with the positioning groove in advance as the swing shaft moves the driving plate to slide. The positioning block enters or lags into the positioning groove when the swing shaft stops moving the driving plate, and cooperates with the positioning groove to position the driving plate.

[0009] As a further improvement, a pulley assembly is provided between the drive shaft and the drive motor.

[0010] As a further improvement, the positioning groove is provided with continuous or multiple discontinuous arc grooves that are concentric and compatible with the arc-shaped outer contour of the positioning block, and the maximum central angle between the arc grooves close to or located at the slot opening in the positioning groove is less than or equal to 180°.

[0011] As a further improvement, the arc shape of the outer contour of the positioning block is an arc shape with a central angle less than or equal to 180°.

[0012] As a further improvement, the driving plate is arranged on the slider of the slide rail assembly, and the slide rail of the slide rail assembly is arranged on the seat plate.

[0013] As a further improvement, a connecting plate connected to the multi-gold sheet device is provided on the slider of the slide rail assembly; and the driving plate is arranged on the connecting plate.

[0014] As a further improvement, a roller is provided on the swing shaft; and a driving groove is provided on the outer side of the positioning groove close to the outer side of the driving plate.

[0015] As a further improvement, the positioning groove is a U-shaped groove.

[0016] As a further improvement, the sum of the central angles of the arc-shaped positioning groove and the arc-shaped outer contour of the positioning block is less than or equal to 360°.

[0017] As a further improvement, the center angle of the arc-shaped outer contour of the positioning block is greater than 180°, and its maximum center angle satisfies that the positioning block can be positioned in the positioning groove and can be separated from the positioning groove when rotating with the driving shaft.

[0018] Compared with the prior art, the utility model comprises a driving assembly including a driving shaft and a driving plate connected to a multi-gold sheet device, and at least two groups of positioning structures arranged along the sliding direction of the driving plate are arranged on the driving plate, and each group of positioning structures includes a positioning groove and a driving groove arranged along the sliding direction of the driving plate, and the positioning groove and the driving groove are provided with openings; a swing arm is arranged on the driving shaft, and a swing shaft is provided on the swing arm, which enters or disengages from the driving groove as the driving shaft drives the swing arm to rotate, and the swing shaft can enter the driving groove as the swing arm rotates, and cooperate with the driving groove to move the driving plate to slide, and the swing shaft can disengage from the driving groove as the driving shaft drives the swing arm to rotate, and stop cooperating with the driving arm and stop moving the driving plate, and a positioning block is provided on the swing arm or / and the driving shaft, which cooperates with the positioning groove as the corresponding group of positioning grooves enters the working position and positions the positioning groove at the working position, and the positioning block is provided with an arc-shaped outer contour which is concentric with the driving shaft and cooperates with the positioning groove, and the positioning block is also provided with a disengagement portion which can be disengaged from the cooperation with the positioning groove, and the disengagement portion and the arc-shaped outer contour form the positioning block. The positioning block is separated from or separated from the positioning groove in advance when the swing shaft moves the driving plate to slide. The positioning block enters or lags into the positioning groove when the swing shaft stops moving the driving plate to cooperate with the positioning groove to position the driving plate. Its beneficial effect is that the swing shaft that rotates with the swing arm enters from the driving groove to cooperate with the driving groove to move the driving plate, or slides out of the driving groove to separate from the driving groove; the positioning block enters the working position to cooperate with the positioning groove and locate the positioning groove in the working position. The cooperation between the positioning block and the positioning groove is a complete mechanical cooperation. The motor does not need to be involved when positioning the positioning groove. The positioning block is set with an arc-shaped outer contour concentric with the driving shaft. When cooperating with the positioning groove, the driving shaft can be allowed to deflect left and right without affecting the positioning of the positioning groove, thereby reducing the demand for the motor stop position and the demand for the positioning sensor. The mechanical separation of the sliding and positioning of the driving multi-gold sheet device and the purely mechanical positioning make the driving and positioning reliable and effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a multi-gold sheet feeding device.

[0020] Figure 2 A schematic structural diagram of the multi-gold sheet feeding device from another angle.

[0021] Figure 3 yes Figure 2 An enlarged schematic diagram of point a.

[0022] Figure 4-5 It is a schematic diagram of the gold sheet changing drive mechanism from different angles.

[0023] Figure 6-10 It is a schematic diagram of the sheet changing process of the gold sheet changing drive mechanism.

[0024] Figure 11-12 It is a schematic diagram of an implementation case in which the positioning groove is set as a U-shaped groove.

[0025] Driving assembly 1, driving shaft 2, swing arm 21, swing shaft 22, positioning block 23, arc-shaped outer contour 24, disengagement portion 25, driving plate 3, positioning groove 31, driving groove 32, driving motor 4, seat plate 5, slide rail assembly 6, slide rail 61, slider 62, connecting plate 7, multi-gold sheet device 8. DETAILED DESCRIPTION

[0026] See also Figure 1-12 A sequin changing drive mechanism includes a seat plate 5, a driving motor 4 disposed on the seat plate 5, a slide rail assembly 6 connecting the seat plate 5 and a multiple sequin device 8, and a driving assembly 1. The multiple sequin device 8 includes multiple sets of feeders. The driving assembly 1 can drive the multiple sequin device 8 to slide and position the corresponding feeders on the multiple sequin device 8 to enter the working position, so that the corresponding feeders can be stably and reliably positioned at the working position to transport the sequins. The seat plate 5 can be used to connect the machine head and the multiple sequin device 8 through the lifting assembly, and to lift the multiple sequin device 8 through the lifting assembly; and the seat plate 5 can be used to position and install the connected driving assembly 1.

[0027] The driving assembly 1 includes a driving shaft 2 for transmitting power to a driving motor 4 and a driving plate 3 connected to a multi-gold sheet device 8. The driving shaft 2 can be rotatably disposed on a seat plate 5 or can be disposed on an independent base plate if necessary.

[0028] The driving plate 3 is provided with at least two groups of positioning structures arranged along the sliding direction of the driving plate 3. Usually, the number of positioning structures corresponds to the number of sequin feeders of multiple sequins, so that each group of positioning structures can correspond to one sequin feeder. Each group of positioning structures includes a positioning groove 31 and a driving groove 32 arranged along the sliding direction of the driving plate 3. The positioning groove 31 and the driving groove 32 are provided with openings, so that the swing shaft 22 can enter or leave the driving groove 32 through the opening of the driving groove 32, and the positioning block 23 can enter or leave the positioning groove 31 through the opening of the positioning groove 31. Figure 3-10 In order to facilitate driving, the positioning groove 31 close to the outer side of the driving plate 3 is provided with a driving groove 32 on the outer side.

[0029] The drive shaft 2 is provided with a swing arm 21, and the swing arm 21 is provided with a swing shaft 22 which enters or escapes from the drive groove 32 as the drive shaft 2 drives the swing arm 21 to rotate. The swing shaft 22 can enter the drive groove 32 in sequence as the swing arm 21 rotates, and cooperates with the drive groove 32 to move the drive plate 3 to slide. The swing arm 21 and / or the drive shaft 2 are provided with a positioning block 23 which cooperates with the positioning groove 31 of the corresponding group entering the working position as the drive shaft 2 rotates, and positions the positioning groove 31 at the working position. The positioning block 23 can be set on the drive shaft 2 or the swing arm 21 as needed, or at the common location of the drive shaft 2 and the swing arm 21. The positioning block 23 is provided with an arc-shaped outer contour 24 which is concentric with the drive shaft 2 and matches with the positioning groove 31. The positioning block 23 is also provided with a disengagement portion 25 which can be disengaged from the matching with the positioning groove 31. The disengagement portion 25 and the arc-shaped outer contour 24 surround the positioning block 23. In this way, when the positioning block 23 rotates with the drive shaft 2, the positioning block 23 with the arc-shaped outer contour 24 can smoothly enter the positioning groove 31 and match with the positioning groove 31 or slide out of the positioning groove 31. This is to facilitate the matching or disengagement with the positioning groove 31, and realize the positioning or disengagement of the positioning groove 31. The disengagement portion 25 can be simplified to a straight chord of the arc-shaped outer contour 24.

[0030] When the driving shaft 2 drives the swing arm 21 to rotate, the swing shaft 22 of the swing arm 21 sequentially enters the driving groove 32 from the opening, and is about to move the driving plate 3, the positioning block 23 is separated from or separated in advance from the cooperation with the positioning groove 31 as the swing shaft 22 moves the driving plate 3, so as to avoid the interference of the positioning block 23 with the sliding driving plate 3 when the driving plate 3 slides. When the driving shaft 2 drives the swing arm 21 to rotate, the swing shaft 22 of the swing arm 21 slides the driving plate 3 through the driving groove 32, and slides to the working position according to the sliding direction to an adjacent positioning groove 31 corresponding to the driving groove 32 at this time, the positioning block 23 enters or lags into the positioning groove 31 as the swing shaft 22 stops moving the driving plate 3, and cooperates with the positioning groove 31 to position the driving plate 3. When the positioning block 23 enters the positioning groove 31, the swing shaft 22 has stopped moving the driving plate 3, and the positioning block 23 has positioned the positioning groove 31. As the drive shaft 2 continues to rotate, the swing shaft 22 drives the swing arm 21 to rotate and turn out from the slot opening of the drive slot 32; and because the outer contour of the positioning block is an arc shape, when the swing shaft 22 is driven by the drive shaft 2 to rotate after it is separated from the drive slot 32, before entering the corresponding drive slot of another positioning structure next time, during this period, the arc-shaped outer contour 24 of the positioning block 23 can still accurately locate the positioning slot 31 of the positioning structure entering the working position, that is, locate the film feeder corresponding to the positioning structure. By positioning the positioning slot 31, that is, positioning the corresponding film feeder completely mechanically, at this time, there is no need for a program to keep the drive motor 4 still, and the drive motor 4 does not bear any driving force; and during this positioning period, the deflection caused by the accuracy of the drive motor 4 or other reasons can completely not affect the positioning of the positioning block 23 on the positioning slot 31, and the positioning structure can have a large tolerance for the accuracy of the drive motor and the stopping accuracy.

[0031] A pulley assembly is provided between the driving shaft 2 and the driving motor 4. Of course, if necessary, the driving motor 4 can directly drive the driving shaft 2, or the motor shaft of the driving motor 4 can constitute the driving shaft 2, and the driving motor 4 can also drive the driving shaft 2 through existing transmission components such as gears.

[0032] In order to facilitate installation and use, the driving plate 3 is arranged on the slider 62 of the slide rail assembly 6, and the slide rail 61 of the slide rail assembly 6 is arranged on the seat plate 5.

[0033] The slide block 62 of the slide rail assembly 6 is provided with a connecting plate 7 connected to the multi-gold sheet device 8; the driving plate 3 is arranged on the connecting plate 7. In order to facilitate the cooperation between the swing shaft 22 and the driving groove 32, the swing shaft 22 is provided with a roller.

[0034] See also Figure 11-12As an implementation example of the positioning groove 31, the positioning groove 31 is a U-shaped groove. The arc-shaped outer contour of the positioning block 23 can cooperate with the U-shaped groove. When the arc-shaped outer contour 24 of the positioning block 23 rotates with the drive shaft 2 and enters the U-shaped groove from the opening, the U-shaped groove is positioned by the arc-shaped outer contour 24, and the arc-shaped contour constitutes the positioning of the U-shaped groove.

[0035] As a further preference, when the positioning block 23 cooperates with the U-shaped groove, the center angle of the circular arc groove is preferably greater than 180°, and the maximum center angle angle must satisfy the positioning block 23 to be able to position the U-shaped groove and to be detached from the positioning groove as the drive shaft 2 rotates. As a further preference, it is greater than or equal to 180° and less than or equal to 300°. So that the positioning block 23 has more arc-shaped outer contours to cooperate with the U-shaped groove to position the U-shaped groove, and when it is greater than 180°, the arc-shaped outer contour 24 of the positioning block 23 has a greater fault tolerance, that is, when the outer diameter of the arc groove contour 24 has a larger angle area to position the U-shaped groove, that is, after the positioning block 23 is positioned on the U-shaped groove, it can still rotate within a certain range of appropriate safety angles. The demand for the accuracy of the motor stop position is greatly reduced, so that the drive motor 4 has a larger range of stop angles. The safety angle range is that the positioning block 23 rotates with the drive shaft 2 and can still maintain the positioning of the U-shaped groove through the outer arc.

[0036] See also Figure 1-10 As a preferred implementation case of the positioning groove 31, the positioning groove 31 is provided with a continuous or multiple discontinuous arc grooves that are concentric and compatible with the arc-shaped outer contour 24 of the positioning block 23. That is, the positioning groove 31 can be set as an arc groove that matches the arc-shaped outer contour 24 of the positioning block 23, and the arc groove can be continuous or discontinuous. In order to facilitate the positioning block 23 to quickly disengage from the positioning groove 31 when it is necessary to disengage from the positioning groove 31, the maximum center angle between the arc grooves close to or located at the notch in the positioning groove 31 is less than or equal to 180°. The center angle of the arc-shaped outer contour 24 of the positioning block 23 can also be less than or equal to 180°.

[0037] As an option in the implementation case of the arc-shaped positioning groove 31, the sum of the center angles of the arc-shaped positioning groove and the arc-shaped outer contour 24 of the positioning block 23 is less than 360°. In this solution, when the center angle of the arc-shaped positioning groove 31 is less than 180°, the center angle of the arc-shaped outer contour of the positioning block 23 can be appropriately increased, that is, the center angle of the arc-shaped outer contour 24 of the positioning block 23 is greater than 180°, and its maximum center angle satisfies that the positioning block can be rotated with the drive shaft to position the positioning groove and can be detached from the positioning groove. Its function and shape can refer to the role of the positioning groove 31 in the implementation case of the U-shaped groove, and its shape can refer to Figure 11-12 .

[0038] When the gold sheet changing drive mechanism of the utility model is in use, taking the positioning groove 31 as an arc-shaped positioning groove as an example, the arc center angle of the positioning groove 31 is 180°, and the arc center angle of the arc-shaped outer contour 24 of the positioning block 23 is slightly less than 180°, about 174.5° in the figure. The working process is as follows.

[0039] Assume that Figure 6 The first group of film feeders enters the working position as the initial position. When the multi-series device 7 needs to be replaced from the current group of film feeders to Figure 6 The other set of film feeders on the right corresponds to Figure 6 That is, the positioning block 23 needs to be replaced from the first positioning groove on the left to the positioning groove on the right. Figure 6-7 , the driving motor 4 is controlled to rotate clockwise, the driving motor 4 drives the driving shaft 2 to rotate, and the swing arm 21 rotates clockwise along with the driving shaft 2 until the swing shaft 22 on the swing arm enters the driving groove on the right side of the first positioning groove. Before the swing shaft 22 moves the driving plate 3, the positioning block 23 still realizes the positioning of the positioning groove 31 through the arc-shaped outer contour 24.

[0040] See also Figure 8-9 As the drive shaft 2 drives the swing arm 21 to continue to rotate, the swing shaft 22 moves the drive plate 3 to slide to the left until the swing shaft 22 slides out of the drive groove on the right side of the first positioning groove and is separated from the drive groove. During the period from when the swing shaft 22 moves the drive plate 3 to when the swing shaft is separated from the drive groove, the positioning block 23 is separated from or prematurely separated from the cooperation with the positioning groove 31 as the swing shaft 22 moves the drive plate 3.

[0041] See also Fig.10 As the drive shaft 2 completely leaves the drive groove on the right side of the first positioning groove, the drive plate 3 slides to the left side, so that the second positioning groove enters the working position. The positioning block 23 enters or lags into the second positioning groove as the swing shaft 22 stops toggling the drive plate 3, and cooperates with the second positioning groove to position the drive plate 3. As the drive shaft 2 continues to rotate, the arc-shaped outer contour 24 of the positioning block 23 completely cooperates with the arc-shaped positioning groove, realizing the switching and positioning of the second film feeder, and the switching and positioning of the third to Nth film feeders can be realized in turn.

[0042] If it is necessary to replace the Nth group of film feeders (N is greater than or equal to 3), the driving motor 4 is required to drive the driving shaft 2 to drive the swing arm 21 to rotate continuously, so that the swing shaft 22 drives the driving plate 3 to slide by cooperating with the driving grooves 32 of the corresponding groups in sequence, until the swing shaft 22 can cooperate with the driving grooves corresponding to the Nth group of positioning grooves 31, and continue to move the driving plate 3 to slide, so that the Nth group of positioning grooves 31 enter the working position, and the positioning block 23 rotating with the driving shaft 2 stops moving the driving plate 3 as the swing shaft 22 stops and enters or lags into the Nth group of positioning grooves 31, and cooperates with the positioning grooves 31 to position the driving plate 3, that is, the Nth group of film feeders are positioned in the working position.

[0043] If it is necessary to replace to Figure 6 The driving motor 4 of the left - hand set of film feeders drives the drive shaft 2 to rotate in the reverse direction. The driving process can refer to the above - mentioned process from left to right.

[0044] The working position in the present utility model is that a film feeder of the multi - gold - film device 8 slides to the film - feeding position. When the multi - gold - film device 8 is installed on the embroidery machine, the film - feeding position is to cooperate with the machine needle to convey the gold film. The U - shaped groove and the arc - shaped positioning groove in the present utility model are only an optimization of the positioning groove. Any groove body that can be positioned or disengaged from the positioning groove by the positioning block 23 rotating with the drive shaft 2 should fall within the protection scope of the present utility model.

Claims

1. A sequin changing drive mechanism, comprising a base plate, a drive motor disposed on the base plate, and a slide rail assembly connecting the base plate and a multiple sequin device, characterized in that: The device also includes a driving assembly, wherein the driving assembly includes a driving shaft for transmitting the power of the driving motor and a driving plate connected to the multi-gold sheet device; the driving plate is provided with at least two groups of positioning structures arranged along the sliding direction of the driving plate, each group of positioning structures includes a positioning groove and a driving groove arranged along the sliding direction of the driving plate, and the positioning groove and the driving groove are provided with an opening for entry and exit; The driving shaft is provided with a swing arm, and the swing arm is provided with a swing shaft which enters or disengages from the driving groove as the driving shaft drives the swing arm to rotate. The swing shaft can enter the driving groove in turn as the swing arm rotates, and cooperates with the driving groove to move the driving plate to slide. The swing arm and / or the driving shaft are provided with a positioning block which cooperates with the positioning groove of the corresponding group entering the working position as the driving shaft rotates, and positions the positioning groove at the working position. The positioning block is provided with an arc-shaped outer contour which is concentric with the driving shaft and cooperates with the positioning groove. The positioning block is also provided with a disengagement portion which can be disengaged from the cooperation with the positioning groove. The disengagement portion and the arc-shaped outer contour form a positioning block. The positioning block disengages from or disengages from the cooperation with the positioning groove in advance as the swing shaft moves the driving plate to slide. The positioning block enters or lags into the positioning groove when the swing shaft stops moving the driving plate, and cooperates with the positioning groove to position the driving plate.

2. The gold sheet changing drive mechanism according to claim 1, characterized in that: A pulley assembly is provided between the driving shaft and the driving motor.

3. The gold sheet changing drive mechanism according to claim 1, characterized in that: The positioning groove is provided with continuous or multiple discontinuous arc grooves which are concentric and adapted to the arc outer contour of the positioning block, and the maximum central angle between the arc grooves close to or located at the notch in the positioning groove is less than or equal to 180°.

4. The gold sheet changing drive mechanism according to claim 1 or 3, characterized in that: The arc shape of the outer contour of the positioning block is an arc shape with a central angle less than or equal to 180°.

5. The gold sheet changing drive mechanism according to claim 1, characterized in that: The driving plate is arranged on the slider of the slide rail assembly, and the slide rail of the slide rail assembly is arranged on the seat plate.

6. The gold sheet changing drive mechanism according to claim 5, characterized in that: A connecting plate connected to the multi-gold sheet device is arranged on the sliding block of the sliding rail assembly; and the driving plate is arranged on the connecting plate.

7. The gold sheet changing drive mechanism according to claim 1, characterized in that: The swing shaft is provided with a roller; the positioning groove close to the outer side of the driving plate is provided with a driving groove on the outer side.

8. The gold sheet changing drive mechanism according to claim 1, characterized in that: The positioning groove is a U-shaped groove.

9. The gold sheet changing drive mechanism according to claim 3, characterized in that: The sum of the central angles of the arc-shaped positioning groove and the arc-shaped outer contour of the positioning block is less than or equal to 360°.

10. The gold sheet changing drive mechanism according to claim 8, characterized in that: The center angle of the arc-shaped outer contour of the positioning block is greater than 180°, and its maximum center angle satisfies the requirement that the positioning block can be positioned in the positioning groove and can be separated from the positioning groove as the driving shaft rotates.

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