CN218927062U

CN218927062U - Push-out unlocking type tool changing device

Info

Publication number: CN218927062U
Application number: CN202222809353.9U
Authority: CN
Inventors: 黄艳; 容锦康; 容啟旋; 邝锦富
Original assignee: Guangdong Jinke Machine Tool Co ltd
Current assignee: Guangdong Jinke Machine Tool Co ltd
Priority date: 2022-10-24
Filing date: 2022-10-24
Publication date: 2023-04-28
Anticipated expiration: 2032-10-24

Abstract

The utility model discloses a push-out unlocking type tool changing device which comprises a base, a main shaft, a rotating seat, a tool changing arm and a first driving piece, wherein the main shaft is rotatably arranged on the base; the rotating seat is rotatably arranged on the base and limited on the base along the axial direction of the main shaft, the rotating seat is connected with the main shaft and can rotate along with the main shaft, and an unlocking plate is arranged at the end part of the rotating seat; the tool changing arm is arranged on the rotating seat in a sliding manner along the axial direction of the main shaft, is positioned between the unlocking plate and the base, is connected with the main shaft and rotates along with the main shaft, two ends of the tool changing arm are respectively provided with a claw for fixing a tool, and are also provided with locking pieces respectively matched with the two claws; the first driving piece is connected with the main shaft and is used for driving the main shaft to move along the axial direction so as to drive the tool changing arm to move along the axial direction of the main shaft, and when the tool changing arm moves towards the unlocking plate, the locking piece can touch and press the unlocking plate so as to enable the clamping jaws to be unlocked. The tool changing device provided by the utility model can shorten the length of the tool changing arm, further improve the rotating speed of the tool changing arm and improve the tool changing efficiency.

Description

Push-out unlocking type tool changing device

Technical Field

The utility model relates to the technical field of machine tool equipment, in particular to a push-out unlocking type tool changing device.

Background

When processing different parts or performing different processes, a numerical control machine tool is generally equipped with a tool magazine and an automatic tool changer for quickly changing tools to improve production efficiency. In the related art, in order to adapt to the assembly requirement, the length of a tool changing arm of the existing automatic tool changing device is large, the rotating speed is low, and the tool changing efficiency is affected.

Disclosure of Invention

The present utility model aims to solve at least one of the technical problems existing in the prior art. Therefore, the utility model provides the push-out unlocking type tool changing device which can shorten the length of the tool changing arm, further improve the rotating speed of the tool changing arm and improve the tool changing efficiency.

According to an embodiment of the utility model, a push-out unlocking type tool changing device comprises: a base; the main shaft is rotatably arranged on the base; the rotating seat is rotatably arranged on the base and is limited on the base along the axial direction of the main shaft, the rotating seat is connected with the main shaft and can rotate along with the main shaft, and an unlocking plate is arranged at the end part of the rotating seat; the tool changing arm is arranged on the rotating seat in a sliding manner along the axial direction of the main shaft, is positioned between the unlocking plate and the base, is connected with the main shaft and rotates along with the main shaft, two ends of the tool changing arm are respectively provided with a claw for fixing a tool, and are also provided with locking pieces respectively matched with the two claws; the first driving piece is connected with the main shaft and used for driving the main shaft to move along the axial direction so as to drive the tool changing arm to move along the axial direction of the main shaft, and when the tool changing arm moves towards the unlocking plate, the locking piece can touch and press the unlocking plate to enable the clamping jaws to be unlocked.

The technical scheme at least has the following beneficial effects: through setting up the tool changing arm between base and unblock board, the locking piece of locating the tool changing arm is configured to remove towards the unblock board and can touch the unblock board so that the jack catch is unlocked, i.e. the tool changing arm is for ejecting unblock, that is to say, after the tool changing device is installed to the lathe, can arrange the tool changing device in the opposite side of tool magazine, can drive the tool changing arm through first driving piece and remove towards the tool magazine this moment, so that the jack catch is unlocked and is carried out the tool changing, consequently, do not occupy the space between tool magazine and the workstation, can shorten the distance between tool magazine and the workstation, just can shorten the length of tool changing arm for the rotation speed of tool changing arm can be improved, effectively improve tool changing efficiency.

According to some embodiments of the utility model, the rotating base further comprises a mounting base and a plurality of guide rods, the mounting base is connected with the base, the plurality of guide rods are respectively connected between the unlocking plate and the mounting base and are arranged at intervals along the circumferential direction of the main shaft, the tool changing arm is provided with a plurality of guide holes, and the guide rods correspondingly penetrate through the guide holes.

According to some embodiments of the utility model, the unlocking plate is provided with a relief hole through which the end of the spindle can pass.

According to some embodiments of the utility model, the mounting seat is provided with a bearing, end plates and a clamping ring which are positioned at two sides of the bearing, the bearing is mounted on the base, and the end plates are connected to the end face of the base.

According to some embodiments of the utility model, the mounting seat is provided with an inner hole, the inner wall of the inner hole is provided with a plurality of circumferentially arranged grooves, the main shaft is provided with convex ribs matched with the grooves, the main shaft penetrates through the inner hole, and the convex ribs are correspondingly accommodated in the grooves.

According to some embodiments of the utility model, the claw comprises a lock rod and a claw part, the claw part is mounted at the end part of the tool changing arm and is provided with a concave position for accommodating a tool, the lock rod is slidably mounted at the tool changing arm, one end of the lock rod extends out of the concave position, when the locking piece is in a locking state, the lock rod can be limited to move towards the direction away from the concave position, and when the locking piece is in an unlocking state, the lock rod is allowed to move towards the direction away from the concave position.

According to some embodiments of the utility model, a first elastic member is disposed between the lock rod and the tool changing arm, and the first elastic member is used for driving the lock rod to extend to the concave position.

According to some embodiments of the utility model, the tool changing arm is connected with a limiting piece, the lock rod is provided with a limiting groove, the limiting groove is arranged along the length direction of the lock rod, and the limiting piece is inserted into the limiting groove and can move relative to the lock rod within the length range of the limiting groove.

According to some embodiments of the utility model, the locking member comprises a cylinder seat, a locking piece and a second elastic member, the cylinder seat is mounted on the tool changing arm, the tool changing arm is provided with a containing cavity, the containing cavity and an inner cavity of the cylinder seat form a slideway, the locking piece is slidably mounted on the slideway, the sliding direction of the locking piece is perpendicular to the axial direction of the locking rod, the other end of the locking rod can extend into the slideway, one end of the locking piece, which faces the unlocking plate, is provided with a push rod, which extends out of the tool changing arm and can be in collision with the unlocking plate, and the second elastic member is arranged on the cylinder seat and is connected with the locking piece and is used for driving the locking piece to move towards the unlocking plate so as to enable the locking piece to block the locking rod from moving towards the direction deviating from the concave position.

According to some embodiments of the utility model, the device further comprises a second driving piece, wherein the output end of the second driving piece is connected with a driving gear, the main shaft is connected with a driven gear meshed with the driving gear, and the second driving piece drives the main shaft to rotate through the driving gear and the driven gear.

Additional aspects and advantages of the utility model will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the utility model.

Drawings

The foregoing and/or additional aspects and advantages of the utility model will become apparent and may be readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view of a tool changer according to an embodiment of the present utility model;

FIG. 2 is a cross-sectional view of a tool changer according to an embodiment of the present utility model;

FIG. 3 is an enlarged view of FIG. 2 at A;

FIG. 4 is a partial cross-sectional view of a tool changer according to an embodiment of the present utility model;

FIG. 5 is a schematic view of a spindle structure according to an embodiment of the present utility model;

fig. 6 is a schematic structural diagram of a mounting seat according to an embodiment of the utility model.

Reference numerals:

a base 100; a sleeve portion 110;

a main shaft 200; ribs 210; a driven gear 220;

a rotating base 300; a mounting base 310; a bearing 311; an end plate 312; a clasp 313; an inner bore 314; a recess 315; a guide bar 320; unlocking plate 330; avoidance hole 331;

tool changing arm 400; a claw 410; a lock lever 411; limit groove 4111; a claw portion 412; a recess 4121; a first elastic member 420; a locking member 430; a cartridge 431; a locking piece 432; ejector rod 4321; a second elastic member 433; a stopper 440; a slideway 450; chute 460;

a first driving member 500;

a second driving member 600; a drive gear 610;

a cutter 700.

Detailed Description

Reference will now be made in detail to the present embodiments of the present utility model, examples of which are illustrated in the accompanying drawings, wherein the accompanying drawings are used to supplement the description of the written description so that one can intuitively and intuitively understand each technical feature and overall technical scheme of the present utility model, but not to limit the scope of the present utility model.

In the description of the present utility model, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present utility model and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present utility model.

In the description of the present utility model, a number means one or more, a number means two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and above, below, within, etc. are understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present utility model, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present utility model can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.

Referring to fig. 1 to 6, an embodiment of the present utility model provides a push-out unlocking type tool changing device, which includes a base 100, a spindle 200, a rotating seat 300, a tool changing arm 400, and a first driving member 500.

Referring to fig. 1, it will be appreciated that the base 100 is for mounting to a machine tool to integrally mount the tool changer to the machine tool. The base 100 is provided with a sleeve portion 110, and the spindle 200 is inserted into the sleeve portion 110 and is rotatably fitted to the sleeve portion 110 via a bearing 311, and the spindle 200 is axially movable relative to the base 100 within a certain range.

Referring to fig. 1 and 2, it can be understood that the rotating base 300 is rotatably mounted at one end of the base 100 and limited to the base 100 along the axial direction of the spindle 200, specifically, the rotating base 300 is partially received in the sleeve portion 110 and sleeved on the outer circumference of the spindle 200, the inner ring of the bearing 311 is mounted on the outer circumference of the rotating base 300, and the outer ring of the bearing 311 is mounted in the sleeve portion 110, that is, the rotating base 300 can rotate around the center line of the spindle 200 with respect to the base 100, but cannot move along the axial direction of the spindle 200 with respect to the base 100. The rotating seat 300 is connected to the spindle 200 and is rotatable with the spindle 200, for example, the rotating seat 300 is spline-connected to the spindle 200.

Referring to fig. 1 to 3, it can be understood that the rotating base 300 includes a mounting base 310, two guide rods 320 and an unlocking plate 330, the two guide rods 320 are respectively connected between the mounting base 310 and the unlocking plate 330, and the two guide rods 320 are circumferentially spaced apart along the spindle 200, the mounting base 310 is mounted on the sleeve portion 110 of the base 100, i.e. the inner ring of the bearing 311 is mounted on the outer periphery of the mounting base 310, the mounting base 310 is provided with an inner hole 314, and the spindle 200 is penetrated through the inner hole 314. Unlocking plate 330 is located on the side of mount 310 facing away from base 100.

Referring to fig. 5 and 6, it can be appreciated that the inner hole 314 of the mounting base 310 is provided with a plurality of grooves 315 arranged circumferentially, the spindle 200 is provided with ribs 210 corresponding to the grooves 315, and the ribs 210 are received in the grooves 315, thereby enabling the rotating base 300 to rotate with the spindle 200. Generally, the length of the ribs 210 is greater than the length of the grooves 315 in the axial direction of the spindle 200, so that the spindle 200 can move in the axial direction within a certain range relative to the rotating base 300, while maintaining a state in which the spindle 200 rotates synchronously with the rotating base 300.

Referring to fig. 1, it can be appreciated that the first driving member 500 is provided as a cylinder and is mounted to the other end of the base 100, and an output shaft of the first driving member 500 is connected to the main shaft 200 so as to drive the main shaft 200 to move in an axial direction within a certain range.

Referring to fig. 1 and 2, it may be understood that the base 100 is further provided with a second driving member 600, the second driving member 600 is configured as a motor, an output end of the second driving member 600 is connected with a driving gear 610, a driven gear 220 meshed with the driving gear 610 is sleeved on the spindle 200, a matching manner of the driven gear 220 and the sleeve portion 110 may refer to a matching manner of the mounting seat 310 and the sleeve portion 110, a matching manner of the driven gear 220 and the spindle 200 may refer to a matching manner of the mounting seat 310 and the spindle 200, and details thereof are omitted, so that the driven gear 220 and the spindle 200 can synchronously rotate, and meanwhile, the spindle 200 can axially move relative to the driven gear 220. Therefore, the second driving member 600 can drive the spindle 200 to rotate through the cooperation of the driving gear 610 and the driven gear 220.

Referring to fig. 1 to 3, it will be appreciated that the tool changing arm 400 has an elongated structure, and a middle portion of the tool changing arm 400 is slidably mounted to the rotary base 300 along the axial direction of the spindle 200. Specifically, the tool changing arm 400 is provided with a guide hole (not shown) corresponding to the guide rod 320, the guide rod 320 is inserted into the guide hole to guide the tool changing arm 400, and the tool changing arm 400 is located between the unlocking plate 330 and the base 100, so that the tool changing arm 400 is slidably engaged with the rotating base 300. The tool changing arm 400 is connected with the spindle 200 and can rotate along with the spindle 200, and meanwhile, the tool changing arm 400 is limited along the axial direction of the spindle 200 and the spindle 200, namely, the tool changing arm 400 cannot move relative to the spindle 200 along the axial direction of the spindle 200. For example, tool changing arm 400 is splined to spindle 200 and is axially positioned by a shoulder (not shown) on spindle 200 engaging a nut.

Referring to fig. 1, it can be understood that the tool changing arm 400 is provided at both ends thereof with jaws 410, respectively, the jaws 410 are used to fix the tool 700, the tool changing arm 400 is further provided with two locking members 430, respectively, the two locking members 430 correspond to the two jaws 410, and the locking members 430 are used to lock or unlock the jaws 410. The locking member 430 is configured to unlock the pawl 410 for replacement of the knife 700 when the locking member 430 is pressed against the unlocking plate 330.

Therefore, the first driving member 500 can drive the spindle 200 to move toward the unlocking plate 330 to drive the tool changing arm 400 to move toward the unlocking plate 330, so that the locking member 430 presses the unlocking plate 330 to unlock the pawl 410 for replacing the tool 700, and then the first driving member 500 drives the spindle 200 and the tool changing arm 400 to move in the opposite direction, so that the locking member 430 is disengaged from the unlocking plate 330, and the pawl 410 is locked to fix the new tool 700 to the tool changing arm 400. Then, the second driving member 600 drives the spindle 200 to rotate, and drives the rotating base 300 and the tool changing arm 400 to rotate synchronously, so that the new tool 700 can be converted from the tool magazine to the workbench, and the first driving member 500 drives the spindle 200 to move towards the unlocking plate 330 again, so that the clamping jaw 410 is unlocked, the new tool 700 can be mounted on the workbench, and the new tool 700 is separated from the tool changing arm 400, so that the tool changing is completed.

In the related art, it is easy for those skilled in the art that the existing tool changing device is located at the same side as the tool magazine, and is located between the tool magazine and the workbench, the tool changing arm is long, the rotation speed is slow, and the tool changing efficiency is low.

According to the technical scheme, the tool changing arm 400 is arranged between the base 100 and the unlocking plate 330, the locking piece 430 arranged on the tool changing arm 400 is configured to move towards the unlocking plate 330 and can touch the unlocking plate 330 to unlock the claw 410, namely, the tool changing arm 400 is pushed out for unlocking, namely, after the tool changing device is installed on a machine tool, the tool changing device can be arranged on the opposite side of the tool magazine, and at the moment, the tool changing arm 400 can be driven to move towards the tool magazine through the first driving piece 500 so as to unlock the claw 410 and change a tool, therefore, the space between the tool magazine and a workbench is not occupied, the distance between the tool magazine and the workbench can be shortened, the length of the tool changing arm 400 can be shortened, the rotating speed of the tool changing arm 400 can be increased, and the tool changing efficiency can be effectively improved.

Referring to fig. 3, it can be understood that the unlocking plate 330 is provided with a relief hole 331, and an inner diameter of the relief hole 331 is greater than an outer diameter of a nut connected to the spindle 200, so that an end of the spindle 200 can pass through the relief hole 331, thereby ensuring that the tool changing arm 400 can approach the unlocking plate 330, enabling the locking member 430 to touch the unlocking plate 330 to unlock, and improving reliability.

Referring to fig. 3, it may be understood that the mounting base 310 is provided with an end plate 312 and a snap ring 313, where the end plate 312 and the snap ring 313 are respectively located at two sides of the bearing 311, so as to realize axial limitation of the bearing 311 on the mounting base 310, the end plate 312 is axially clamped to the mounting base 310, and meanwhile, the end plate 312 is fixedly connected to an end surface of the base 100 through a screw, so as to realize axial limitation of the rotating base 300 on the base 100. Simple structure and easy realization.

Referring to fig. 1 and 4, it can be understood that the claw 410 includes a lock lever 411 and a claw portion 412, the claw portion 412 is in a semi-arc structure and is fixedly mounted to an end portion of the tool changing arm 400, and the claw portion 412 is provided with a recess 4121 for receiving the tool 700. The openings of the recesses 4121 of the claw portions 412 at both ends of the tool changing arm 400 are opposite. The tool changing arm 400 is provided with a chute 460, and the chute 460 extends to a recess 4121, and the lock lever 411 is slidably mounted on the chute 460 and has one end extending to the recess 4121.

Referring to fig. 4, it can be understood that the locking member 430 includes a barrel seat 431, a locking piece 432, and a second elastic member 433, the second elastic member 433 is configured as a spring, the barrel seat 431 is mounted on a side of the tool changing arm 400 facing away from the unlocking plate 330, the tool changing arm 400 is provided with a receiving cavity corresponding to the barrel seat 431, the receiving cavity and an inner cavity of the barrel seat 431 form a slide 450, a sliding direction of the slide 450 is perpendicular to a sliding direction of the lock lever 411, and the other end of the lock lever 411 extends into the slide 450. The locking piece 432 is slidably mounted on the slide 450, one end of the locking piece 432 facing the unlocking plate 330 is provided with a push rod 4321, the push rod 4321 extends out of the tool changing arm 400 towards the unlocking plate 330 and can be abutted against the unlocking plate 330, the second elastic piece 433 is arranged between the locking piece 432 and the cylinder seat 431, and under the elastic action of the second elastic piece 433, the locking piece 432 can be driven to move towards the unlocking plate 330, so that the locking piece 432 blocks the locking rod 411 to move towards the direction deviating from the concave position 4121, namely, a locking state is achieved, and the tool 700 is locked on the tool changing arm 400. When the tool changing arm 400 moves toward the unlocking plate 330, the ejector rod 4321 presses the unlocking plate 330 and pushes the locking piece 432 to move reversely, and the second elastic member 433 is in a compressed state, so that the locking rod 411 is allowed to move in a direction away from the recess 4121, namely, in an unlocking state, so that the tool 700 can be replaced.

Referring to fig. 4, it may be understood that a first elastic member 420 is disposed between the lock rod 411 and the tool changing arm 400, the first elastic member 420 is configured as a spring, the first elastic member 420 is sleeved on the lock rod 411, two ends of the first elastic member 420 respectively abut against a step position of an inner wall of the chute 460 and a shoulder of the lock rod 411, under the elastic force of the first elastic member 420, the lock rod 411 can be driven to extend to a concave position 4121, so that the claw 410 keeps a locking state under the acting force of the first elastic member 420, the tool 700 is prevented from falling off, the safety is improved, and meanwhile, when the tool 700 is pulled out, the first elastic member 420 is compressed to unlock, and the tool changing is not affected.

Referring to fig. 4, it may be understood that the tool changing arm 400 is connected with a limiting member 440, the limiting member 440 may be a limiting screw, the locking lever 411 is provided with a limiting groove 4111 disposed along a length direction of the locking lever 411, the length of the limiting groove 4111 is greater than an outer diameter of the limiting member 440, and the limiting member 440 is inserted into the limiting groove 4111, so that the locking lever 411 can move within a length range of the limiting groove 4111, but cannot be separated from the tool changing arm 400, thereby improving reliability.

The embodiments of the present utility model have been described in detail with reference to the accompanying drawings, but the present utility model is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present utility model.

Claims

1. A push-out unlocking type tool changing device, comprising:

a base;

the main shaft is rotatably arranged on the base;

the rotating seat is rotatably arranged on the base and is limited on the base along the axial direction of the main shaft, the rotating seat is connected with the main shaft and can rotate along with the main shaft, and an unlocking plate is arranged at the end part of the rotating seat;

the tool changing arm is arranged on the rotating seat in a sliding manner along the axial direction of the main shaft, is positioned between the unlocking plate and the base, is connected with the main shaft and rotates along with the main shaft, two ends of the tool changing arm are respectively provided with a claw for fixing a tool, and are also provided with locking pieces respectively matched with the two claws;

the first driving piece is connected with the main shaft and used for driving the main shaft to move along the axial direction so as to drive the tool changing arm to move along the axial direction of the main shaft, and when the tool changing arm moves towards the unlocking plate, the locking piece can touch and press the unlocking plate to enable the clamping jaws to be unlocked.

2. The push-out unlocking type tool changing device according to claim 1, wherein: the rotary seat further comprises a mounting seat and a plurality of guide rods, the mounting seat is connected with the base, the guide rods are respectively connected between the unlocking plate and the mounting seat and are arranged along the circumferential direction of the main shaft at intervals, the tool changing arm is provided with a plurality of guide holes, and the guide rods correspondingly penetrate through the guide holes.

3. A push-out unlocking type cutter changing device according to claim 1 or 2, wherein: the unlocking plate is provided with an avoidance hole, and the end part of the main shaft can pass through the avoidance hole.

4. A push-out unlocking tool changer according to claim 2, wherein: the mounting seat is provided with a bearing, end plates and clamping rings, wherein the end plates and the clamping rings are positioned on two sides of the bearing, the bearing is mounted on the base, and the end plates are connected to the end faces of the base.

5. A push-out unlocking tool changer according to claim 2, wherein: the mounting seat is provided with an inner hole, the inner wall of the inner hole is provided with a plurality of circumferentially arranged grooves, the main shaft is provided with convex ribs matched with the grooves, the main shaft penetrates through the inner hole, and the convex ribs are correspondingly accommodated in the grooves.

6. The push-out unlocking type tool changing device according to claim 1, wherein: the claw comprises a lock rod and a claw part, the claw part is arranged at the end part of the tool changing arm and is provided with a concave position for accommodating a tool, the lock rod is slidably arranged on the tool changing arm, one end of the lock rod extends out of the concave position, when the locking piece is in a locking state, the lock rod can be limited to move in a direction deviating from the concave position, and when the locking piece is in an unlocking state, the lock rod is allowed to move in a direction deviating from the concave position.

7. The push-out unlocking type tool changing device according to claim 6, wherein: a first elastic piece is arranged between the lock rod and the tool changing arm and is used for driving the lock rod to extend out to the concave position.

8. The push-out unlocking type tool changing device according to claim 7, wherein: the tool changing arm is connected with a limiting part, the lock rod is provided with a limiting groove, the limiting groove is arranged along the length direction of the lock rod, and the limiting part is inserted into the limiting groove and can move relative to the lock rod within the length range of the limiting groove.

9. The push-out unlocking type tool changing device according to claim 6, wherein: the locking piece includes drum seat, locking piece and second elastic component, the drum seat install in the tool changing arm, the tool changing arm is equipped with and holds the chamber, hold the chamber with the inner chamber of drum seat forms the slide, locking piece slidable mounting in the slide, just the slip direction of locking piece with the axial of locking lever is perpendicular, the other end of locking lever can stretch into the slide, the locking piece orientation the one end of unblock board is equipped with the ejector pin, the ejector pin stretch out in the tool changing arm and can with the unblock board is contradicted, the second elastic component is located the drum seat and with the locking piece is connected, is used for order about the locking piece orientation the unblock board removes, so that the locking piece blocks the locking lever is towards deviating from the direction of concave position removes.

10. The push-out unlocking type tool changing device according to claim 1, wherein: the driving gear is connected to the output end of the second driving piece, the main shaft is connected with a driven gear meshed with the driving gear, and the second driving piece drives the main shaft to rotate through the driving gear and the driven gear.