A packing device for motorcycle inner tube production

Abstract

The present application relates to the field of motorcycle inner tube production, especially to a packaging device for motorcycle inner tube production. The technical problem to be solved is that the inner tube cannot be effectively fixed during the winding process, the wound inner tube has an irregular shape, which makes the subsequent bundling and packaging work difficult, and the inner tube is separated from the equipment during winding, which reduces the production efficiency of the inner tube. The technical scheme of the present application is a packaging device for motorcycle inner tube production, which comprises a conveyor belt and a support frame; the right side of the conveyor belt is provided with a support frame. The sliding of the mechanical arm drives the first mechanical claw and the claw hand, realizing the bundling and transmission of the inner tube, the second mechanical claw rotates to drive the fixing rod to wind the inner tube, the single claw of the second mechanical claw clamps and fixes the inner tube, facilitating the subsequent bundling of the inner tube, and the fixing plate drives the limiting plate to rotate counterclockwise, preventing the two ends of the folded inner tube from drooping.

Description

TECHNICAL FIELD

[0001] The application relates to the field of motorcycle inner tube production, and in particular to a packaging device for motorcycle inner tube production. BACKGROUND

[0002] A full-automatic inner tube packaging machine is disclosed in Chinese Patent No. CN202222370396.1. The machine is designed with automatic equipment for each operation process. The inner tube suction adopts a suction fan, the inner tube locking cap adopts automatic locking cap equipment, the inner tube winding adopts an automatic winding machine, and the inner tube bundling adopts an automatic bundling machine. Thus, all manual operation processes are completed by automatic equipment. However, the device does not consider the characteristics of the inner tube itself and does not process details. For example, during the winding process, the non-fixed part of the inner tube is driven to rotate by the rotational force generated when the inner tube is wound, and then the inner tube is shaken. The wound inner tube has an irregular shape, which makes the subsequent bundling work difficult, and the bundled inner tube is loose. Moreover, the subsequent packaging of the inner tube is not facilitated.

[0003] Further, since the disengagement of the wound inner tube is considered, the equipment has a small clamping force when winding the inner tube, which causes the inner tube to disengage from the equipment during winding. The disengaged inner tube needs to be collected and wound again, which greatly reduces the production efficiency of the inner tube. SUMMARY

[0004] In order to overcome the shortcomings that the inner tube cannot be effectively fixed during the winding process, the wound inner tube has an irregular shape, which makes the subsequent bundling and packaging work difficult, and the inner tube disengages from the equipment during winding, and the production efficiency of the inner tube is reduced, the application provides a packaging device for motorcycle inner tube production.

[0005] The technical scheme of the application is as follows: a packaging device for motorcycle inner tube production, comprising a conveyor belt and a support frame; the right side of the conveyor belt is provided with the support frame; further comprising a feeding system, a grabbing assembly, a first mechanical claw, a claw hand, a winding assembly, a fixing rod and a protection assembly; the rear side of the conveyor belt is provided with the feeding system for placing rubber bands; the support frame is provided with the grabbing assembly for controlling the transmission of the bundled inner tube; the grabbing assembly is provided with the first mechanical claw for grabbing the inner tube; the first mechanical claw is provided with a plurality of claw hands for bundling the inner tube; each claw hand is provided with a recess for clamping the fixed rubber band; the upper side of the support frame is provided with the winding assembly for winding the inner tube; the left side of the winding assembly is provided with a plurality of fixing rods symmetrically arranged above and below for fixing the inner tube; the non-fixed end of each fixing rod is provided with a warping portion for turning the inner tube off; and the upper side of the support frame is provided with the protection assembly for protecting the inner tube during winding.

[0006] As a preferred embodiment of the present invention, the gripping component includes a robotic arm; a robotic arm is provided on the upper side of the support frame for sliding to control the first robotic claw; the first robotic claw is movably connected to the robotic arm.

[0007] As a preferred embodiment of the present invention, the winding assembly includes a support platform and a second mechanical claw; the support platform is movably disposed on the upper side of the support frame; the second mechanical claw is connected to the left side of the support platform for rotating and fixing the inner tube; the left side of the second mechanical claw is fixedly connected to several fixing rods.

[0008] As a preferred embodiment of the present invention, the protective assembly includes a connecting plate, a fixing plate, and a limiting plate; two symmetrical connecting plates are fixedly connected to the upper side of the support frame; a fixing plate for rotating to fix the inner tube is connected to the front side of each connecting plate; the two fixing plates are fixedly connected to each other; a limiting plate for sliding to limit and fix the inner tube is connected to each fixing plate.

[0009] As a preferred embodiment of the present invention, each claw is provided with a gripping part for gripping and fixing the inner tube.

[0010] As a preferred embodiment of the present invention, the feeding system includes a fixed frame, a limiter, and an extrusion plate; the fixed frame is fixedly connected to the rear side of the support frame; the limiter for fixing and restricting the rubber strap is fixedly connected to the fixed frame; the upper end of the limiter is provided with an indentation for limiting the rubber strap, and the upper end of the limiter is provided with a transverse groove; the upper side of the fixed frame is provided with an extrusion plate for lifting and extruding the rubber strap for feeding; the extrusion plate is located outside the limiter.

[0011] As a preferred embodiment of the present invention, it further includes limiting blocks and elastic elements; the upper part of the limiting device has a plurality of grooves arranged in a ring array; the upper part of the limiting device is movably connected with a plurality of limiting blocks for limiting the rubber straps; the upper part of the limiting device is fixedly connected with a plurality of elastic elements; each elastic element is fixedly connected to an adjacent limiting block; each limiting block and each elastic element are located in a corresponding groove.

[0012] As a preferred embodiment of the present invention, it further includes rollers; each claw has a roller rotatably connected to its front end to prevent the claw from scratching the inner tube.

[0013] As a preferred embodiment of the present invention, it further includes a first driven roller; each fixed plate has two left-right symmetrical first driven rollers rotatably connected to its lower part to reduce friction between the inner tube and the fixed plate.

[0014] As a preferred technical scheme of the present application, the second driven roller is further included; each of the two fixed plates is connected with a second driven roller rotating for reducing the friction between the inner tube and the fixed plate; and each of the two limiting plates is connected with another second driven roller rotating for reducing the friction between the inner tube and the limiting plate.

[0015] The present application has the following advantages: the present application realizes the turning of the claw hand controlled by the first mechanical claw, the rubber band is detached from the recess and is sleeved on the inner tube with the rolling completed, and the convenient bundling of the inner tube is realized;

[0016] The first mechanical claw and the claw hand are driven to slide by the mechanical arm, and the bundling and transmission of the inner tube are realized;

[0017] The inner tube is rolled by the fixed rod driven by the rotation of the second mechanical claw, the inner tube is clamped and fixed by the single claw of the second mechanical claw, and the bundling of the inner tube is facilitated;

[0018] The limiting plate is driven to rotate counterclockwise by the fixed plate, the two ends of the folded inner tube are prevented from drooping, the middle part of the inner tube is prevented from being tightly attached to the second mechanical claw, and the rolling effect of the inner tube is avoided to be reduced;

[0019] The limiting plate is moved to the fixed plate to be folded, the inner tube during rolling is limited, the inner tube is prevented from swinging, the inner tube is prevented from being unable to be normally rolled, and the normal production of the inner tube is ensured;

[0020] The inner tube is contacted by the roller, the front end of the claw hand is prevented from scratching and damaging the inner tube, and the yield of the produced inner tube is ensured;

[0021] The first driven roller reduces the friction between the two ends of the folded inner tube and the fixed plate, the two ends of the folded inner tube are prevented from being scratched and damaged by the fixed plate during rolling, and the yield of the produced inner tube is further ensured;

[0022] The second driven roller reduces the friction between the inner tube and the lower part of the opposite side of the limiting plate and the opposite side of the fixed plate, the rotating inner tube is prevented from being scratched and damaged by the lower part of the opposite side of the limiting plate and the opposite side of the fixed plate, and the yield of the produced inner tube is further ensured. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a first kind of three-dimensional structure schematic view of the present application;

[0024] Figure 2 It is a second kind of three-dimensional structure schematic view of the present application;

[0025] Figure 3 It is a part of three-dimensional structure schematic view of the present application;

[0026] Figure 4 It is a first mechanical claw and claw hand combined three-dimensional structure schematic view of the present application;

[0027] Figure 5 It is a perspective view of the combination of the winding assembly and the protection assembly of the present application;

[0028] Figure 6 It is a perspective view of the winding assembly of the present application;

[0029] Figure 7 It is a perspective view of the protection assembly of the present application;

[0030] Figure 8 It is a perspective view of the feeding system of the present application;

[0031] Figure 9 It is a partial sectional view of the feeding system of the present application;

[0032] Figure 10 It is a perspective view of the first mechanical claw, the claw hand and the roller combination of the present application; Figure 9 It is an enlarged view of the area at A in the above figure;

[0033] Figure 11 It is a perspective view of the first mechanical claw, the claw hand and the roller combination of the present application;

[0034] Figure 12 It is a perspective view of the first mechanical claw, the claw hand and the roller combination of the present application; Figure 11 It is an enlarged view of the area at B in the above figure;

[0035] Figure 13 It is a perspective view of the winding assembly, the first driven roller and the second driven roller combination of the present application.

[0036] In the figure, the marks are: 1-conveying belt, 2-support frame, 3-first mechanical claw, 4-claw hand, 4001-recess, 4002-grabbing part, 5-fixed rod, 5001-warping part, 101-first sliding rail, 102-first electric sliding block, 103-mechanical arm, 201-first driving piece, 202-first motor, 203-bearing table, 204-second mechanical claw, 301-connection plate, 302-fixed plate, 303-limiting plate, 304-second motor, 305-second sliding rail, 306-second electric sliding block, 401-fixed frame, 402-limiter, 40201-internal recess, 40202-groove, 403-pressing plate, 404-second driving piece, 501-limiting block, 502-elastic piece, 601-roller, 701-first driven roller, 702-second driven roller. DETAILED DESCRIPTION

[0037] Reference herein to an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments.

[0038] Embodiment 1

[0039] As Figures 3-7 shown, a packaging device for motorcycle inner tube production comprises a conveyor belt 1 and a support frame 2; the right side of the conveyor belt 1 is provided with the support frame 2;

[0040] It also comprises a feeding system, a grabbing assembly, a first mechanical claw 3, a claw hand 4, a winding assembly, a fixed rod 5, and a protection assembly; the rear side of the conveyor belt 1 is provided with the feeding system; the support frame 2 is provided with the grabbing assembly; the grabbing assembly is provided with the first mechanical claw 3; the first mechanical claw 3 is provided with four claw hands 4; each claw hand 4 is provided with a recess 4001; the upper side of the support frame 2 is provided with the winding assembly; the left side of the winding assembly is provided with two fixed rods 5 which are symmetrical vertically; the non-fixed end of each fixed rod 5 is provided with a warping part 5001; the upper side of the support frame 2 is provided with the protection assembly; the motorcycle inner tube after being folded once is transmitted to the space between the two fixed rods 5 on one side of the support frame 2 through the conveyor belt 1, and the inner tube is rotated and wound by the winding assembly, at the same time, the inner tube is limited and fixed by the two fixed rods 5, the warping part 5001 prevents the inner tube from falling off the fixed rod 5, and the normal operation of the inner tube winding work is ensured, while the inner tube is rotating, the protection assembly is gradually closed to limit the rotating inner tube, preventing the inner tube from being thrown out of the equipment during rotation and winding, when the inner tube rotation and winding are completed, the grabbing assembly drives the first mechanical claw 3 and the claw hand 4 to move to the feeding system, the claw hand 4 is controlled by the first mechanical claw 3 to expand from the closed state, the recess 4001 clamps the rubber strap, and the rubber strap is transmitted to the middle position of the wound inner tube, the claw hand 4 is turned over by the first mechanical claw 3, the rubber strap falls off from the recess 4001 and is sleeved on the wound inner tube, realizing convenient bundling of the inner tube, the inner tube is grabbed and fixed by the other end of the claw hand 4, the inner tube is pulled out of the two fixed rods 5, the inner tube is sent to the next process for packaging and sealing by the first mechanical claw 3 controlling the claw hand 4, ensuring the continuity of the inner tube production work and improving the efficiency of the inner tube production.

[0041] The grabbing assembly comprises a mechanical arm 103; the upper side of the support frame 2 is provided with the mechanical arm 103; the first mechanical claw 3 is movably connected to the mechanical arm 103; the first mechanical claw 3 and the claw hand 4 are driven to slide by the mechanical arm 103, so that the inner tube is bundled and transmitted.

[0042] The winding assembly comprises a bearing table 203 and a second mechanical claw 204; the upper side of the support frame 2 is movably provided with the bearing table 203; the left upper part of the bearing table 203 is connected with the second mechanical claw 204; the left side of the second mechanical claw 204 is fixedly connected with two fixed rods 5; the fixed rods 5 are driven to rotate by the second mechanical claw 204 to wind the inner tube; during the winding process, the single claw of the second mechanical claw 204 is unfolded to be parallel; after the winding is completed, the single claw of the second mechanical claw 204 clamps and fixes the inner tube, so as to facilitate the subsequent bundling of the inner tube.

[0043] The protection assembly comprises a connecting plate 301, a fixed plate 302 and a limiting plate 303; the upper side of the support frame 2 is fixedly connected with two front and rear symmetrical connecting plates 301; each connecting plate 301 is connected with a fixed plate 302 on the front side; the two fixed plates 302 are fixedly connected; each fixed plate 302 is connected with a limiting plate 303; when the inner tube is rotated and wound, the limiting plate 303 is counterclockwise rotated by the fixed plate 302 from front to back as the reference, so as to prevent the two ends of the folded inner tube from drooping, so that the middle part of the inner tube is tightly attached to the second mechanical claw 204, thereby avoiding reducing the winding effect of the inner tube; at the same time, the limiting plate 303 moves towards the fixed plate 302 to fold, so as to limit the inner tube during winding, prevent the inner tube from swinging, avoid the inner tube from being unable to be normally wound, and ensure the normal production of the inner tube.

[0044] Each claw hand 4 is provided with a grabbing part 4002; when the claw hand 4 is turned over and the rubber band is sleeved on the wound inner tube from the recessed part 4001, the tail part of the bundled rubber inner tube is grabbed and fixed by the grabbing part 4002, and then is transmitted to the next process, so as to further ensure the continuity of the inner tube production work.

[0045] Further comprising a driving assembly, the driving assembly comprising a first sliding rail 101, a first electric sliding block 102, a first driving piece 201, a first motor 202, a second motor 304, a second sliding rail 305 and a second electric sliding block 306; two first sliding rails 101 are symmetrically and fixedly connected to the upper side of the support frame 2; one first electric sliding block 102 is slidably arranged on each first sliding rail 101; the upper side of the two first electric sliding blocks 102 is fixedly connected with the mechanical arm 103; the mechanical arm 103 is driven by the two first electric sliding blocks 102 to slide left and right on the first sliding rail 101, so as to realize the transmission of the rubber band and the inner tube; two first driving pieces 201 are symmetrically and fixedly connected to the upper side of the support frame 2, and the first driving piece 201 is an electric push rod; the telescopic ends of the two first driving pieces 201 are fixedly connected with a bearing table 203; the bearing table 203 is fixedly connected with the first motor 202; the output end of the first motor 202 is fixedly connected with a second mechanical claw 204; the bearing table 203 and the first motor 202 are driven by the first driving piece 201 to move left and right, so as to control the second mechanical claw 204 to wind the inner tube; a second motor 304 is fixedly connected to the front connecting plate 301 on the upper side of the support frame 2; the output end of the second motor 304 is fixedly connected with a fixed plate 302; one second sliding rail 305 is fixedly connected to each fixed plate 302; one second electric sliding block 306 is slidably arranged on each second sliding rail 305; each second electric sliding block 306 is fixedly connected with a limiting plate 303; the limiting plate 303 is driven by the second electric sliding block 306 to ascend and descend on the second sliding rail 305, and at the same time, the fixed plate 302 is driven by the second motor 304 to rotate counterclockwise, so as to drive the limiting plate 303 to rotate counterclockwise, limit the inner tube during winding, prevent the inner tube from swinging, avoid the inner tube from being unable to be normally wound, and ensure the normal production of the inner tube.

[0046] Embodiment 2

[0047] On the basis of embodiment 1, as shown in Figures 8-10 the feeding system comprises a fixing frame 401, a limiting device 402 and a pressing plate 403; the fixing frame 401 is fixedly connected to the rear side of the support frame 2; the limiting device 402 is fixedly connected to the fixing frame 401; the upper end of the limiting device 402 is provided with a recessed portion 40201, and a horizontal slot is formed in the upper end of the limiting device 402; the pressing plate 403 is arranged on the upper side of the fixing frame 401; the pressing plate 403 is located outside the limiting device 402; when the first mechanical claw 3 grabs the rubber band, the rubber band on the limiting device 402 is pressed upward by the rising of the pressing plate 403, so that the uppermost rubber band is contracted and clamped into the recessed portion 40201; the rubber band is grabbed from the recessed portion 40201 by the claw hand 4 controlled by the first mechanical claw 3, so that the recessed portion 4001 clamps the rubber band, and the convenient feeding of the rubber band is realized.

[0048] The feeding system further comprises a second driving member 404; the second driving member 404 is fixed on the fixed frame 401 and is an electric push rod; the telescopic end of the second driving member 404 is fixed on the lower side of the extrusion plate 403; the second driving member 404 is used to control the lifting of the extrusion plate 403, so as to realize the feeding of the rubber bandage.

[0049] Further comprising a limiting block 501 and an elastic member 502; a plurality of annular array grooves 40202 are formed in the upper part of the limiting device 402; a plurality of limiting blocks 501 are movably connected to the upper part of the limiting device 402; a plurality of elastic members 502 are fixed to the upper part of the limiting device 402, and the elastic members 502 are springs; each elastic member 502 is fixed to the adjacent limiting block 501; each limiting block 501 and each elastic member 502 are located in the corresponding groove 40202; when the extrusion plate 403 rises and the rubber bandage is extruded to the recessed part 40201, the limiting block 501 blocks the rubber bandage, and after each rubber bandage passes, the extrusion plate 403 stops extruding the rubber bandage, so that only one rubber bandage passes each time, preventing multiple rubber bandages from sliding into the recessed part 40201 when the rubber bandage reaches the groove 40202, avoiding the claw hand 4 from grasping multiple rubber bandages to bundle the inner tube at one time, causing waste of rubber bandage, and being conducive to saving production cost.

[0050] Embodiment 3

[0051] Based on the embodiment 2, as shown in Figure 11 and Figure 12 , the feeding system further comprises a roller 601; one roller 601 is rotatably connected to the front end of each claw hand 4; when the claw hand 4 is turned over and the rubber bandage is sleeved on the inner tube after rolling, the roller 601 contacts the inner tube, preventing the front end of the claw hand 4 from scratching and damaging the inner tube, and ensuring the yield of the produced inner tube.

[0052] Embodiment 4

[0053] Based on the embodiments 1-3, as shown in Figure 1 , Figure 2 and Figure 13 , the feeding system further comprises a first driven roller 701; two left and right symmetrical first driven rollers 701 are rotatably connected to the lower part of each fixed plate 302; when the inner tube is rotated and rolled, the first driven roller 701 reduces the friction between the two ends of the folded inner tube and the fixed plate 302, preventing the two ends of the folded inner tube from being scratched by the fixed plate 302 during rolling, and further ensuring the yield of the produced inner tube.

[0054] The second driven roller 702 is further included; one second driven roller 702 is connected to the lower part of each of the two facing sides of the fixed plate 302; another second driven roller 702 is connected to each of the two facing sides of the limiting plate 303; when the inner tube is about to be completely wound, the limiting plate 303 moves to the fixed plate 302 to fold, the inner tube is fixed, at the same time, the second driven roller 702 is driven by the rotating inner tube to rotate, thereby reducing the friction between the lower part of the facing side of the limiting plate 303 and the facing side of the fixed plate 302, preventing the rotating inner tube from being scraped by the lower part of the facing side of the limiting plate 303 and the facing side of the fixed plate 302, and further ensuring the yield of the produced inner tube.

[0055] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A packaging device for motorcycle inner tube production, comprising a conveyor belt (1) and a support frame (2); the right side of the conveyor belt (1) is provided with the support frame (2); characterized in that: The device also comprises a feeding system, a grabbing assembly, a first mechanical claw (3), a claw hand (4), a winding assembly, a fixing rod (5) and a protection assembly; the rear side of the conveying belt (1) is provided with the feeding system for placing rubber bands; the support frame (2) is provided with the grabbing assembly for conveying the inner tube after bundling; the grabbing assembly is provided with the first mechanical claw (3) for grabbing the inner tube; the first mechanical claw (3) is provided with a plurality of claw hands (4) for bundling the inner tube; each claw hand (4) is provided with a recess (4001) for clamping the fixed rubber band; the upper side of the support frame (2) is provided with the winding assembly for winding the inner tube; the left side of the winding assembly is provided with a plurality of fixing rods (5) for fixing the inner tube; the non-fixed end of each fixing rod (5) is provided with a warping part (5001) for the inner tube to fall off; the upper side of the support frame (2) is provided with the protection assembly for protecting the inner tube during winding.

2. A packing device for motorcycle inner tube production as claimed in claim 1, characterized in that: The grabbing assembly comprises a mechanical arm (103); the upper side of the support frame (2) is provided with the mechanical arm (103) for controlling the first mechanical claw (3); the mechanical arm (103) is movably connected with the first mechanical claw (3).

3. A packing device for motorcycle inner tube production as claimed in claim 2, wherein: The winding assembly comprises a bearing table (203) and a second mechanical claw (204); the upper side of the support frame (2) is movably provided with the bearing table (203); the left side of the bearing table (203) is connected with the second mechanical claw (204) for rotating to fix the inner tube; the left side of the second mechanical claw (204) is fixedly connected with the plurality of fixing rods (5).

4. A packing device for motorcycle inner tube production as claimed in claim 3, characterized in that: The protection assembly comprises a connecting plate (301), a fixing plate (302) and a limiting plate (303); the upper side of the support frame (2) is fixedly connected with two front and rear symmetrical connecting plates (301); the front side of each connecting plate (301) is connected with a fixing plate (302) for rotating to fix the inner tube; the two fixing plates (302) are fixedly connected; each fixing plate (302) is connected with a limiting plate (303) for sliding to limit and fix the inner tube.

5. A packing device for motorcycle inner tube production as claimed in claim 1, wherein: Each claw hand (4) is provided with a grabbing part (4002) for grabbing and fixing the inner tube.

6. A packing device for motorcycle inner tube production as claimed in claim 4, wherein: The feeding system comprises a fixing frame (401), a limiting device (402) and a pressing plate (403); the rear side of the support frame (2) is fixedly connected with the fixing frame (401); the fixing frame (401) is fixedly connected with the limiting device (402) for fixing and limiting the rubber band; the upper end of the limiting device (402) is provided with a recess (40201) for limiting the rubber band, and a horizontal groove is formed in the upper end of the limiting device (402); the upper side of the fixing frame (401) is provided with the pressing plate (403) for lifting to press the rubber band for feeding; the pressing plate (403) is located outside the limiting device (402).

7. A packing device for motorcycle inner tube production as claimed in claim 6, characterized in that: It further includes a limiting block (501) and an elastic member (502); a plurality of annular arrayed grooves (40202) are formed in the upper portion of the limiter (402); a plurality of limiting blocks (501) for limiting the rubber band are movably connected to the upper portion of the limiter (402); a plurality of elastic members (502) are fixedly connected to the upper portion of the limiter (402); each elastic member (502) is fixedly connected to the adjacent limiting block (501); each limiting block (501) and each elastic member (502) are located in the corresponding groove (40202).

8. A packing device for motorcycle inner tube production as claimed in claim 5, wherein: It further includes a roller (601); one roller (601) for preventing the claw hand (4) from scratching and damaging the inner tube is rotatably connected to the front end of each claw hand (4).

9. A packing device for motorcycle inner tube production as claimed in claim 4, wherein: It further includes a first driven roller (701); two first driven rollers (701) for reducing the friction between the inner tube and the fixed plate (302) are rotatably connected to the lower portion of each fixed plate (302).

10. A packing device for motorcycle inner tube production as claimed in claim 9, characterized in that: It further includes a second driven roller (702); one second driven roller (702) for reducing the friction between the inner tube and the fixed plate (302) is rotatably connected to each of the opposite sides of the two fixed plates (302); another second driven roller (702) for reducing the friction between the inner tube and the limiting plate (303) is rotatably connected to each of the opposite sides of the two limiting plates (303).

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