Bidirectional walking mechanism

Abstract

The invention belongs to the technical field of intelligent storage equipment manufacturing, and particularly relates to a bidirectional walking mechanism which comprises a frame body, X-direction moving mechanisms are fixedly arranged on the left side and the right side of the bottom of the frame body, and Y-direction moving mechanisms are arranged on the front side and the rear side of the frame body through lifting mechanisms in the frame body. The lifting mechanism enables the lowest end of the Y-direction moving mechanism to be lower than the lowest end of the X-direction moving mechanism and enables the lowest end of the Y-direction moving mechanism to be higher than the lowest end of the X-direction moving mechanism. The Y-direction moving mechanism is arranged on the frame body through the lifting mechanism, the two-way walking mechanism is designed, and the problem that an existing trolley is not flexible and cannot be switched is solved.

Description

Technical Field

[0001] The present application belongs to the technical field of intelligent warehousing equipment manufacturing, and specifically relates to a bidirectional walking mechanism. Background Art

[0002] The wheels of the traditional trolley used for lifting objects move in a straight line within the track, for example, moving along the X-axis direction of the spatial coordinate system or along the Y-axis direction of the spatial coordinate system, so as to move the lifted materials. However, this trolley that can only move in one direction is not flexible, so it is necessary to design a trolley that can switch the moving direction. Summary of the invention

[0003] The purpose of the present application is mainly to address the shortcomings of the prior art. A bidirectional walking mechanism is designed by setting a Y-direction moving mechanism on a frame through a lifting mechanism, so that when the frame needs to move along the Y direction, the lifting mechanism makes the Y-direction moving mechanism extend to the point where the lower end of the Y-direction moving mechanism is lower than the lower end of the Y-direction moving mechanism, and then the frame is driven to move in the Y direction by the Y-direction moving mechanism; and when the frame needs to move along the X direction, the lifting mechanism makes the Y-direction moving mechanism shrink to the point where the lower end of the Y-direction moving mechanism is higher than the lower end of the X-direction moving mechanism, and then the frame is driven to move in the X direction by the X-direction moving mechanism, and the X-direction movement can be guaranteed; thereby solving the problem that the existing trolley is inflexible and cannot be switched.

[0004] In order to achieve the above purpose, the technical solution adopted in this application is:

[0005] A bidirectional walking mechanism comprises a frame, wherein X-direction moving mechanisms are fixedly arranged on the left and right sides of the bottom of the frame, and Y-direction moving mechanisms are arranged on the front and rear sides of the frame through a lifting mechanism, wherein the lifting mechanism can make the lowest end of the Y-direction moving mechanism lower than the lowest end of the X-direction moving mechanism, and the lifting mechanism can make the lowest end of the Y-direction moving mechanism higher than the lowest end of the X-direction moving mechanism.

[0006] Preferably, the frame is hollow, and the lifting mechanism is fixed on the inner bottom wall of the frame; when the lifting mechanism extends upward, the lifting mechanism drives the Y-direction moving mechanism to move upward so that the lowest end of the Y-direction moving mechanism is higher than the lowest end of the X-direction moving mechanism; when the lifting mechanism contracts, the lifting mechanism drives the Y-direction moving mechanism to move downward so that the lowest end of the Y-direction moving mechanism is lower than the lowest end of the X-direction moving mechanism.

[0007] Preferably, the lifting mechanism comprises four lifting units, and the four lifting units are evenly distributed around a central axis of the frame that is perpendicular to the upper surface of the frame.

[0008] Preferably, the lifting mechanism further comprises a lifting drive and a transmission, the output end of the lifting drive is transmission-connected to the transmission input end of the transmission, the transmission has four transmission output ends, and each transmission output end is transmission-connected to one of the lifting units.

[0009] Preferably, the lifting unit includes a base, a screw rod, a top column, and a driving nut. The top column is fixedly connected to the Y-direction moving mechanism. The base is provided with a cavity opening upward. The driving nut is coaxially rotatably arranged on the base at the top of the cavity. The top end of the screw rod is rotatably connected to the top column. The driving nut is threadedly connected to both ends of the screw rod, and the driving nut is connected to the transmission output end of the transmission device through transmission.

[0010] Preferably, the transmission device includes three transmission rods, a first bevel gear, a second bevel gear, and an active rod. The first bevel gear is respectively arranged at both ends of each of the transmission rods, and the first bevel gear is arranged at one end of the active rod. A first gear is coaxially fixedly provided on each of the driving nuts. Two second gears meshing with the first gear are arranged on the base around the driving nut. A second bevel gear is coaxially fixedly provided on the upper end surface of each second gear. The connecting line segments between the two second gears and the first gear are all located on the same plane parallel to the upper surface of the base. The angle between the two connecting line segments is ninety degrees, and the lengths of the two connecting line segments are equal. The four bases are respectively located at four vertices on a virtual rectangle. A transmission rod is respectively arranged on the three sides of the virtual rectangle. The first bevel gears at both ends of the transmission rod are respectively meshed with the second bevel gear on one of the bases. The first bevel gear on the active rod is meshed with the second bevel gear on one of the bases at a side of the virtual rectangle where no transmission rod is arranged. The lifting driver is a first motor, and the output shaft of the first motor is transmission-connected to the active rod.

[0011] Preferably, the Y-direction moving mechanism includes a Y-direction support frame, a Y roller, a Y belt, and a second motor. The Y-direction support frame includes a base plate and two ear plates. The two ear plates are respectively located at opposite ends of the base plate, and the two ear plates are parallel to each other. The Y roller is arranged on each ear plate, and the end face of the Y roller is parallel to the ear plate. The base plate is fixedly connected to the execution end of the lifting mechanism, and a second motor is arranged on the ear plate. The output shaft of the second motor is connected to the wheel axle of the Y roller through the Y belt.

[0012] Preferably, the ear plate is also provided with a tensioning mechanism cooperating with the Y belt.

[0013] Preferably, the ear plate is provided with four mounting holes, and the four mounting holes are respectively located at four vertices of a virtual isosceles trapezoid on the ear plate, the bottom side and the top side of the virtual isosceles trapezoid on the ear plate are parallel to the lower surface of the frame, the two mounting holes located on the bottom side of the virtual isosceles trapezoid are used to mount the Y roller, and the two mounting holes located on the top side of the virtual isosceles trapezoid are used to mount the driving wheel and the driven wheel respectively, the Y belt is sleeved on the driving wheel, the driven wheel, and the wheel axles of the two Y rollers, the output shaft of the second motor is connected to the driving wheel in a transmission manner, and the tensioning mechanism comprises a first slide groove and a second slide groove, both of which are located in the virtual trapezoid, the length line of the first slide groove and the length line of the second slide groove are parallel to the bottom side of the virtual trapezoid, a slider is respectively slidably provided in the first slide groove and the second slide groove, each of the sliders is respectively provided with a pulley for the Y belt, and a limiting device cooperating with the slider is respectively provided on the ear plate corresponding to the first slide groove and the second slide groove.

[0014] Compared with the prior art, this application has the following beneficial effects:

[0015] The present application adopts a method of setting a Y-direction moving mechanism on a frame through a lifting mechanism, and designs a bidirectional walking mechanism, so that when the frame needs to move along the Y direction, the lifting mechanism makes the Y-direction moving mechanism extend to the point where the lower end of the Y-direction moving mechanism is lower than the lower end of the Y-direction moving mechanism, and then relies on the Y-direction moving mechanism to drive the frame to move in the Y direction; and when the frame needs to move along the X direction, the lifting mechanism makes the Y-direction moving mechanism shrink to the point where the lower end of the Y-direction moving mechanism is higher than the lower end of the X-direction moving mechanism, and then relies on the X-direction moving mechanism to drive the frame to move in the X direction, and can ensure the movement in the X direction; thereby solving the problem that the existing trolley is inflexible and cannot be switched. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of this application;

[0017] Figure 2 It is a structural schematic diagram of the Y-direction moving mechanism;

[0018] Figure 3 It is the relationship diagram between the Y-direction moving mechanism and the lifting mechanism;

[0019] Figure 4 It is a structural schematic diagram of the X-direction moving mechanism;

[0020] Figure 5 It is the relationship diagram between the X-direction moving mechanism and the lifting mechanism;

[0021] Figure 6 It is a structural schematic diagram of the lifting mechanism;

[0022] Figure 7 This is the exploded diagram of the lifting mechanism;

[0023] Figure 8 A connection relationship diagram between the transmission rod and the first bevel gear, the second bevel gear, the first gear, the second gear, the drive nut, and the lead screw;

[0024] Fig. 9 This is a schematic diagram of the application when using the X-direction moving mechanism to move;

[0025] Fig.10 This is a schematic diagram of the present application when using the Y-direction moving mechanism for movement.

[0026] Among them, 1. frame; 2. base; 3. screw; 4. top column; 5. drive nut; 6. transmission rod; 7. first bevel gear; 8. second bevel gear; 9. first motor; 10. Y direction support frame; 10-1. bottom plate; 10-2. ear plate; 11. Y roller; 12. Y belt; 13. second motor; 14. mounting hole; 15. driving wheel; 16. driven wheel; 17. first slide groove; 18. second slide groove; 19. bolt; 20. first gear; 21. X roller; 22. slider; 23. pulley; 24. second gear. DETAILED DESCRIPTION

[0027] like Figure 1-10 As shown, a bidirectional walking mechanism includes a frame 1, wherein X-direction moving mechanisms are fixedly provided on the left and right sides of the bottom of the frame 1, and Y-direction moving mechanisms are provided on the front and rear sides of the frame 1 through a lifting mechanism. The lifting mechanism can make the lowest end of the Y-direction moving mechanism lower than the lowest end of the X-direction moving mechanism, and the lifting mechanism can make the lowest end of the Y-direction moving mechanism higher than the lowest end of the X-direction moving mechanism.

[0028] In this embodiment, when in use, a bracket is used, and a plurality of transverse tracks and longitudinal tracks are arranged on the top of the bracket, the transverse tracks are perpendicular to each other and are located on the same plane, the transverse tracks are parallel to each other, and the longitudinal tracks are parallel to each other; then the bracket can be placed on the track, and then after the goods are hoisted onto the bracket, if the bracket is to move along the longitudinal track, the lower end of the Y-direction moving mechanism is made lower than the lower end of the X-direction moving mechanism by the lifting mechanism, at this time, the Y-direction moving mechanism is convenient for contacting the longitudinal track to realize Y-direction movement, and the X-direction moving mechanism is not in contact with the longitudinal track due to the contact between the lower end of the Y-direction moving mechanism and the longitudinal track, so that the movement of the Y-direction moving mechanism on the longitudinal track will not be affected. When the bracket needs to move on the transverse track, the lower end of the Y-direction moving mechanism is made higher than the lower end of the X-direction moving mechanism by the lifting mechanism, and at this time, the lower end of the X-direction moving mechanism contacts the transverse track, causing the lower end of the Y-direction moving mechanism to be suspended, so that the movement of the bracket 1 on the transverse track is not affected.

[0029] There are two ways to set the Y-direction moving mechanism by the lifting device. The first way is: the frame 1 is hollow inside, and the lifting mechanism is fixed on the inner bottom wall of the frame 1. When the lifting mechanism is extended upward, the lifting mechanism drives the Y-direction moving mechanism to move upward so that the lowest end of the Y-direction moving mechanism is higher than the lowest end of the X-direction moving mechanism. When the lifting mechanism is retracted, the lifting mechanism drives the Y-direction moving mechanism to move downward so that the lowest end of the Y-direction moving mechanism is lower than the lowest end of the X-direction moving mechanism. After the setting, the lifting mechanism will lift the Y-direction moving mechanism upward relative to the frame 1 after the extension, so that the Y-direction moving mechanism is suspended; and the lifting mechanism will lower the Y-direction moving mechanism after the retraction, so that the lowest end of the Y-direction moving mechanism is lower than the lowest end of the X-direction moving mechanism, so that the X-direction moving mechanism is suspended.

[0030] The second method is: the frame 1 is hollow, and the lifting mechanism is fixed on the inner top wall of the frame 1. When the lifting mechanism extends upward, the lifting mechanism drives the Y-direction moving mechanism to move downward so that the lowest end of the Y-direction moving mechanism is lower than the lowest end of the X-direction moving mechanism. When the lifting mechanism contracts, the lifting mechanism drives the Y-direction moving mechanism to move upward so that the lowest end of the Y-direction moving mechanism is higher than the lowest end of the X-direction moving mechanism.

[0031] Specifically, the lifting mechanism includes four lifting units, and the four lifting units are evenly distributed around the central axis of the frame body that is perpendicular to the upper surface of the frame body 1. After such arrangement, the four lifting units are lifted synchronously when in use, and the force received by the Y-direction moving mechanism during lifting is evenly distributed through the four synchronously lifted lifting units, thereby avoiding local deformation caused by uneven force.

[0032] As a preferred embodiment, the lifting mechanism further comprises a lifting drive and a transmission, wherein the output end of the lifting drive is transmission-connected to the transmission input end of the transmission, the transmission has four transmission output ends, and each transmission output end is transmission-connected to one of the lifting units.

[0033] As a preferred embodiment, the lifting unit includes a base 2, a screw rod 3, a top column 4, and a driving nut 5. The top column 4 is fixedly connected to the Y-direction moving mechanism. The base 2 is provided with a cavity opening upward. The driving nut 5 is coaxially rotatably arranged on the base 2 at the top of the cavity. The top end of the screw rod 3 is rotatably connected to the top column 4. The driving nut 5 is threadedly connected to both ends of the screw rod 3, and the driving nut 5 is transmission-connected to the transmission output end of the transmission.

[0034] After such arrangement, the output end of the lifting drive rotates the driving nut 5 through the transmission device, and the driving nut 5 rotates to rotate the screw rod 3 to achieve the up and down movement of the screw rod 3, thereby achieving lifting.

[0035] As a preferred method, Figure 6 , Figure 7 , Figure 8As shown, the transmission includes three transmission rods 6, a first bevel gear 7, a second bevel gear 8, and an active rod. The first bevel gear 7 is respectively arranged at both ends of each transmission rod 6, and the first bevel gear 7 is arranged at one end of the active rod. A first gear 20 is coaxially fixedly sleeved on each of the driving nuts 5. Two second gears 24 meshing with the first gear 20 are arranged on the base 2 around the driving nut 5. A second bevel gear 8 is coaxially fixedly arranged on the upper end surface of each second gear 24. The connecting line segments between the two second gears 24 and the first gear 20 are both located parallel to the On the same plane of the upper surface of the base 2, the angle between the two connecting line segments is ninety degrees, the lengths of the two connecting line segments are equal, the four bases 2 are respectively located at four vertices on a virtual rectangle, a transmission rod 6 is arranged on each of the three sides of the virtual rectangle, the first bevel gears 7 at both ends of the transmission rod 6 are meshed with the second bevel gear 8 on one of the bases, the first bevel gear 7 on the active rod is meshed with the second bevel gear 8 on one of the bases 2 at the side of the virtual rectangle where the transmission rod 6 is not arranged, the lifting driver is a first motor 9, and the output shaft of the first motor 9 is connected to the active rod. After such arrangement, the first motor 9 drives the active rod to rotate, thereby driving a lifting unit, and the other lifting units are connected in series through the transmission rod 6, so that the first motor 9 can drive all the lifting units at the same time. Specifically, the first bevel gear 7 on the active rod drives the second bevel gear 8 on the base 1, and the first bevel gear 7 on the transmission rod 6 is also meshed with the second bevel gear 8. Therefore, when the active rod rotates, it can not only drive the second bevel gear 8 to rotate, but also drive the transmission rod 6 to rotate, thereby achieving the transmission effect. Such a transmission is a purely mechanical structure and is not easy to fail.

[0036] As a preferred mode, the Y-direction moving mechanism comprises a Y-direction support frame 10, a Y roller 11, a Y belt 12, and a second motor 13. The Y-direction support frame 10 comprises a bottom plate 10-1 and two ear plates 10-2. The two ear plates 10-2 are respectively located at opposite ends of the bottom plate 10-1. The two ear plates 10-2 are parallel to each other. Each ear plate 10-2 is provided with the Y roller 11. The end surface of the Y roller 11 is parallel to the ear plate 10-2. The bottom plate 10-1 is fixedly connected to the execution end of the lifting mechanism. The ear plate 10-2 is provided with a second motor 13. The output shaft of the second motor 13 is connected to the wheel shaft of the Y roller 11 through the Y belt 12. After such a configuration, the second motor 13 rotates to drive the Y roller 11 to roll through the Y belt 12, thereby realizing the movement in the Y direction. The ear plate 10 - 2 is provided to facilitate the installation of the Y roller 11 , and also to facilitate the X-direction moving mechanism to be suspended when the base plate 10 - 1 is lowered.

[0037] Of course, a transmission shaft is commonly provided on the two ear plates 10-2, and the transmission shaft is parallel to the base plate 10-1. One end of the transmission shaft is connected to the axle of the Y roller 11 on one ear plate 10-2, and the other end of the transmission shaft is connected to the axle of the Y roller 11 on the other ear plate 10-2. In this way, the Y rollers 11 on the two ear plates 10-2 can be connected by transmission, so that the Y rollers 11 on the two ear plates 10-2 can rotate synchronously.

[0038] As a preferred mode, the ear plate 10-2 is also provided with a tensioning mechanism that cooperates with the Y belt 12. Through the tensioning mechanism, it is convenient to adjust the tightness of the Y belt 12.

[0039] As a preferred embodiment, four mounting holes 14 are provided on the ear plate 10-2, and the four mounting holes 14 are respectively located at the four vertices of a virtual isosceles trapezoid on the ear plate 10-2, and the bottom and top sides of the virtual isosceles trapezoid on the ear plate 10-2 are parallel to the lower surface of the frame 1, and the two mounting holes 14 located on the bottom side of the virtual isosceles trapezoid are used to install the Y roller 11, and the two mounting holes 14 located on the top side of the virtual isosceles trapezoid are used to install a driving wheel 15 and a driven wheel 16, respectively, and the Y belt 12 is sleeved on the driving wheel 15, the driven wheel 16, and the two Y rollers 11 The output shaft of the second motor 13 is connected to the driving wheel 15 in a transmission manner. The tensioning mechanism includes a first slide slot 17 and a second slide slot 18. The first slide slot 17 and the second slide slot 18 are both located in the virtual trapezoid. The length line of the first slide slot 17 and the length line of the second slide slot 18 are both parallel to the bottom edge of the virtual trapezoid. A slider 22 is provided in each of the first slide slot 17 and the second slide slot 18. Each of the sliders 22 is provided with a pulley 23 for the Y belt 12. A limiting device is provided on the ear plate 10-2 corresponding to the first slide slot 17 and the second slide slot 18 to cooperate with the slider 22. After such a setting, when adjusting the tightness, the position of the slider 22 in the first slide slot 17 and / or the position of the slider in the second slide slot 18 is changed; after adjustment, the slider 22 can be fixed by the limiting device.

[0040] Preferably, Figure 2 and Figure 3As shown, the limiting device is a bolt 19, and the length line of the bolt 19 in the first slide groove 17 is parallel to the first slide groove 17, and the bolt 19 in the second slide groove 18 is parallel to the second slide groove 18. After such arrangement, the tightness can be adjusted by changing the length of the bolt 19 screwed out of the slider 22. For example, if the length of the bolt 19 screwed out of the slider 22 is long, the end of the bolt 19 facing away from the slider 22 presses against the end in the first slide groove 17 or the second slide groove 18, and the pulley 23 on the slider 22 squeezes the Y belt 12, making the Y belt 12 tighter; if the bolt 19 is screwed into the slider 22 so that the part of the bolt 19 exposed outside the slider 22 is shorter, the pulley 23 squeezes the Y belt 12 less, thereby making the Y belt 12 looser.

Claims

1. A bidirectional walking mechanism, comprising a frame (1), characterized in that: X-direction moving mechanisms are fixedly provided on both left and right sides of the bottom of the frame (1); a Y-direction moving mechanism is provided on both front and rear sides of the frame (1) via a lifting mechanism; the lifting mechanism can make the lowest end of the Y-direction moving mechanism lower than the lowest end of the X-direction moving mechanism; and the lifting mechanism can make the lowest end of the Y-direction moving mechanism higher than the lowest end of the X-direction moving mechanism.

2. A bidirectional walking mechanism according to claim 1, characterized in that: The frame (1) is hollow inside, and the lifting mechanism is fixed on the inner bottom wall of the frame (1). When the lifting mechanism is extended upward, the lifting mechanism drives the Y-direction moving mechanism to move upward so that the lowest end of the Y-direction moving mechanism is higher than the lowest end of the X-direction moving mechanism. When the lifting mechanism is retracted, the lifting mechanism drives the Y-direction moving mechanism to move downward so that the lowest end of the Y-direction moving mechanism is lower than the lowest end of the X-direction moving mechanism.

3. A bidirectional walking mechanism according to claim 1, characterized in that: The lifting mechanism comprises four lifting units, and the four lifting units are evenly distributed around a central axis of the frame body that is perpendicular to the upper surface of the frame body (1).

4. A bidirectional walking mechanism according to claim 3, characterized in that: The lifting mechanism further comprises a lifting driver and a transmission device. The output end of the lifting driver is transmission-connected to the transmission input end of the transmission device. The transmission device has four transmission output ends, and each transmission output end is transmission-connected to one of the lifting units.

5. A bidirectional walking mechanism according to claim 4, characterized in that: The lifting unit comprises a base (2), a screw rod (3), a top column (4), and a driving nut (5); the top column (4) is fixedly connected to the Y-direction moving mechanism; the base (2) is provided with a cavity opening upward; the driving nut (5) is coaxially rotatably arranged on the top of the cavity on the base (2); the top end of the screw rod (3) is rotatably connected to the top column (4); the driving nut (5) is threadedly connected to both ends of the screw rod (3); and the driving nut (5) is drivingly connected to the transmission output end of the transmission device.

6. A bidirectional walking mechanism according to claim 5, characterized in that: The transmission device comprises three transmission rods (6), a first bevel gear (7), a second bevel gear (8), and an active rod. The first bevel gear (7) is respectively arranged at both ends of each transmission rod (6). The first bevel gear (7) is arranged at one end of the active rod. A first gear (20) is coaxially fixedly sleeved on each driving nut (5). Two second gears (24) meshing with the first gear (20) are arranged on the base (2) around the driving nut (5). A second bevel gear (8) is coaxially fixedly arranged on the upper end surface of each second gear (24). The connecting line segments between the two second gears (24) and the first gear (20) are both located parallel to the first gear (20). On the same plane of the upper surface of the base (2), the angle between the two connecting line segments is ninety degrees, and the lengths of the two connecting line segments are equal. The four bases (2) are respectively located at four vertices on a virtual rectangle. A transmission rod (6) is respectively arranged on the three sides of the virtual rectangle. The first bevel gears (7) at both ends of the transmission rod (6) are respectively meshed with the second bevel gear (8) on one of the bases (2). The first bevel gear (7) on the active rod is meshed with the second bevel gear (8) on one of the bases (1) at a side of the virtual rectangle where the transmission rod (6) is not arranged. The lifting drive is a first motor (9), and the output shaft of the first motor (9) is transmission-connected to the active rod.

7. A bidirectional walking mechanism according to claim 1, characterized in that: The Y-direction moving mechanism comprises a Y-direction support frame (10), a Y roller (11), a Y belt (12), and a second motor (13). The Y-direction support frame (10) comprises a base plate (10-1) and two ear plates (10-2). The two ear plates (10-2) are respectively located at two opposite ends of the base plate (10-1). The two ear plates (10-2) are parallel to each other. Each ear plate (10-2) is provided with the Y roller (11). The end surface of the Y roller (11) is parallel to the ear plate (10-2). The base plate (10-1) is fixedly connected to the execution end of the lifting mechanism. The ear plate (10-2) is provided with a second motor (13). The output shaft of the second motor (13) is connected to the wheel shaft of the Y roller (11) through the Y belt (12).

8. A bidirectional walking mechanism according to claim 7, characterized in that: The ear plate (10-2) is also provided with a tensioning mechanism that cooperates with the Y belt (12).

9. A bidirectional walking mechanism according to claim 8, characterized in that: The ear plate (10-2) is provided with four mounting holes (14), and the four mounting holes (14) are respectively located at the four vertices of a virtual isosceles trapezoid on the ear plate (10-2). The bottom side and the top side of the virtual isosceles trapezoid on the ear plate (10-2) are parallel to the lower surface of the frame (1). The two mounting holes (14) located on the bottom side of the virtual isosceles trapezoid are used to mount the Y roller (11), and the two mounting holes (14) located on the top side of the virtual isosceles trapezoid are used to mount the driving wheel (15) and the driven wheel (16), respectively. The Y belt (12) is sleeved on the driving wheel (15), the driven wheel (16), and the wheel axles of the two Y rollers (11). The output shafts of the second motors (13) are drivingly connected to the driving wheel (15); the tensioning mechanism comprises a first slide groove (17) and a second slide groove (18); the first slide groove (17) and the second slide groove (18) are both located in the virtual trapezoid; the length line of the first slide groove (17) and the length line of the second slide groove (18) are both parallel to the bottom side of the virtual trapezoid; a slider (22) is slidably arranged in each of the first slide groove (17) and the second slide groove (18); each of the sliders (22) is provided with a pulley (23) for the Y belt (12); and a limiting device is provided on the ear plate (10-2) corresponding to the first slide groove (17) and the second slide groove (18) and matched with the slider (22).

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