CN111122371A

CN111122371A - Ink wear resistance tester

Info

Publication number: CN111122371A
Application number: CN202010029550.1A
Authority: CN
Inventors: 刘志平; 彭博文; 洪晴
Original assignee: Shenzhen Yaode Technology Co ltd
Current assignee: Shenzhen Yaode Technology Co ltd
Priority date: 2020-01-13
Filing date: 2020-01-13
Publication date: 2020-05-08

Abstract

The invention discloses an ink wear resistance testing machine which comprises a rack, a workbench, a grinding belt, a pressurizing assembly, a first turntable assembly, a second turntable assembly, a first transmission assembly and a turn number counter. The workstation sets up in the frame for place the product that awaits measuring, the top of workstation and the surface that is used for contacting the product that awaits measuring are located to the grinding tape, pressure boost subassembly relies on its gravity to hold the grinding tape pressure in the workstation, first carousel subassembly is used for twining the grinding tape, second carousel subassembly is located between first carousel subassembly and the workstation and is used for supporting the grinding tape, first carousel subassembly and second carousel subassembly all rotate locate the frame on, the number of turns counter is used for taking notes second carousel subassembly's the number of turns of rotating. First drive assembly includes first drive belt, first action wheel and the first follow driving wheel, and first action wheel is connected in second carousel subassembly, and first action wheel passes through first drive belt to be connected in the first follow driving wheel, and the first follow driving wheel is connected in first carousel subassembly.

Description

Ink wear resistance tester

Technical Field

The invention relates to the technical field of flexible circuit board quality detection, in particular to a printing ink wear-resistant testing machine.

Background

In the process of manufacturing the flexible circuit board, a certain amount of printing ink is required to be printed on the surface layer of the circuit board to form an ink layer, and the ink layer can form a protective layer on the circuit board to prevent the circuit board from being oxidized. In order to detect the durability of the ink layer, the ink layer needs to be subjected to an abrasion resistance test.

Most of the existing testing methods manually adopt a friction piece to rub the surface of the ink layer, the wear-resisting degree of the ink layer is determined by observing and measuring the change of the ink layer, and if the ink layer is still reserved after a certain amount of rubbing times, the wear-resisting strength of the ink layer is proved to be qualified. But the friction dynamics of different testers are different, and same tester also hardly guarantees the friction dynamics unchangeably at the friction in-process, therefore the same friction number of times is difficult to guarantee unanimously to the degree of scraping of inhaling of printing ink layer to lead to easily carrying out the erroneous judgement to the qualification degree of printing ink layer.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the utility model provides a wear-resisting test machine of printing ink for provide stable friction dynamics, inhale the uniformity of scraping the degree to the printing ink layer under guaranteeing same test condition.

In order to solve the technical problems, the invention adopts the technical scheme that:

an ink wear resistance tester comprising:

a frame;

the workbench is arranged on the rack and used for placing a product to be tested;

the grinding belt is arranged above the workbench and is used for contacting the surface of a product to be detected;

the pressurizing assembly is used for pressing and holding the grinding belt on the workbench by means of the gravity of the pressurizing assembly;

the first rotating disc assembly comprises a first rotating disc and a first rotating shaft, the first rotating disc is sleeved on the first rotating shaft, and one end of the grinding belt is wound on the first rotating disc;

the second rotating disc assembly is arranged between the first rotating disc assembly and the workbench and comprises a second rotating disc and a second rotating shaft, the second rotating disc is sleeved on the second rotating shaft, and the second rotating disc is used for supporting the grinding belt;

the first transmission assembly comprises a first transmission belt, a first driving wheel and a first driven wheel, the first driving wheel is coaxially connected with the second rotating shaft, the first driving wheel is connected with the first driven wheel through the first transmission belt, and the first driven wheel is coaxially connected with the first rotating shaft; and

and the turn number counter is connected to the second rotating shaft and used for recording the turn number of the second rotating shaft.

Furthermore, the ink wear resistance testing machine further comprises a third turntable assembly, the third turntable assembly and the second turntable assembly are respectively arranged on two opposite sides of the workbench, and the other end of the grinding belt is wound on the third turntable assembly.

Furthermore, one end of the pressurizing assembly is rotatably connected to the rack, and the other end of the pressurizing assembly is pressed on the grinding belt.

The pressurizing assembly further comprises a connecting piece, a guide shaft and a pressing piece, the connecting piece is rotatably connected to the rack, the guide shaft is connected to the connecting piece, and the pressing piece is connected to the guide shaft and used for pressing and holding the grinding belt on the workbench.

Furthermore, the pressurizing assembly further comprises an adjusting weight and a supporting piece, wherein the supporting piece is sleeved on the guide shaft and detachably connected to the guide shaft, and the adjusting weight is arranged on the supporting piece.

Furthermore, the pressurizing assembly further comprises a first spring, and the first spring is sleeved on the guide shaft and is arranged between the supporting piece and the connecting piece.

Further, pressure boost subassembly still includes stop device, stop device includes support, first running roller and second running roller, the leg joint in the guiding axle, first running roller with the second running roller rotate respectively connect in the support, first running roller with the second running roller set up respectively in press the relative both sides of holding the piece, just the axis of first running roller with the axis of second running roller is parallel to each other, the abrasive belt wear to locate in proper order first running roller with press between holding the piece and the second running roller with press between holding the piece.

Furthermore, the pressurizing assembly comprises a connecting piece, a guide shaft and a pressing and holding piece, the connecting piece is fixed on the rack, a through hole is formed in the connection piece, the pressurizing assembly is inserted into the through hole and can move in the through hole along the vertical direction, and the pressurizing assembly is pressed and held on the grinding belt.

Further, the pressure boost subassembly includes guiding axle and pressure and holds the piece, the guiding axle is portable to be worn to locate in the through-hole, the pressure is held the piece and is connected in the guiding axle and be used for with the abrasive band pressure is held on the workstation.

Further, the printing ink wear resistance testing machine further comprises a driving device and a second transmission assembly, the second transmission assembly comprises a second driving wheel, a second driven wheel and a second transmission belt, the second driving wheel is connected to the driving device, the second driving wheel is connected to the second driven wheel through the second transmission belt, and the second driven wheel is coaxially connected with the second rotating shaft.

The embodiment of the invention has the following beneficial effects:

the product to be tested is placed on the working platform, the grinding belt is contacted with the ink layer on the surface of the product to be tested, the grinding belt passes through the second turntable and is wound on the first turntable, the second rotating shaft is rotated, the second turntable and the first driving wheel both rotate along with the second rotating shaft, the first driven wheel rotates along with the first driving wheel under the transmission of the first transmission belt, the first rotating shaft rotates along with the first driven wheel so as to drive the first turntable to rotate, the synchronous rotation of the first turntable and the second turntable drives the grinding belt to move on the surface of the product to be tested, under the action of the pressurizing assembly, the grinding belt and the surface of the product to be tested generate friction so that the grinding belt can absorb and scrape the ink on the surface of the product to be tested, under the same test environment, the gravity of the pressurizing assembly is certain, so that the force applied to the surface of the grinding belt is stable, and the friction force between the grinding belt and the ink layer is, therefore, under the condition that the grinding belt moves for the same distance, the suction and scraping degrees of the ink layer are consistent, whether the wear-resisting degree of the ink layer is qualified or not can be judged only by setting the moving distance of the proper grinding belt, the whole judging process has stronger objectivity, and the probability of misjudgment is greatly reduced. And, the number of turns counter record the number of turns of rotation of second pivot, and the removal distance of abrasive band can be calculated very fast through the number of turns of rotation of second pivot and the radius of second carousel, consequently can be through the removal distance of the number of turns control abrasive band of monitoring second pivot to the frictional strength of control to the printing ink layer, and the thickness of the printing ink layer that detects the reservation, with this whether qualified of the abrasive resistance who judges the printing ink layer. In addition, the second rotating disc can play a guiding role in the movement of the grinding belt, and the grinding belt is prevented from shifting in the moving process.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Wherein:

FIG. 1 is a schematic structural view of an ink abrasion resistance tester according to a first embodiment;

FIG. 2 is a schematic structural diagram of a supercharging assembly according to a first embodiment;

FIG. 3 is a schematic view of another angle of the abrasion resistance tester for ink in the first embodiment;

FIG. 4 is a schematic structural view of an ink abrasion resistance tester according to a second embodiment;

FIG. 5 is a schematic structural diagram of a supercharging assembly according to a second embodiment;

description of reference numerals:

1. a frame; 2. a work table; 3. a grinding belt; 4. a pressurizing assembly; 41. a connecting member; 411. a through hole; 42. a guide shaft; 43. a pressing member; 44. a support member; 45. adjusting the weight; 46. a first limiting device; 461. a support; 462. a first roller; 463. a second roller; 47. a first spring; 48. a second spring; 5. a first carousel assembly; 51. a first rotating shaft; 52. a first turntable; 6. a second turntable assembly; 61. a second rotating shaft; 62. a second turntable; 7. a first transmission assembly; 71. a first drive wheel; 72. a first drive belt; 73. a first driven wheel; 8. a number of turns counter; 9. a third turntable assembly; 91. a third rotating shaft; 92. a third turntable; 10. a drive device; 11. a second transmission assembly; 111. a second drive wheel; 112. a second drive belt; 113. a second driven wheel; 12. a fourth turntable assembly; 121. a fourth rotating shaft; 122. a fourth turntable; 13. a gap; 14. a third roller; 15. a fourth roller; 16. a motor speed regulator.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

Referring to fig. 1, an embodiment of the invention provides an ink wear resistance testing machine for detecting the wear resistance of an ink layer, such as an ink layer on a surface of a circuit board or an ink layer on a surface of another product. This printing ink wearability test machine includes that frame 1, workstation 2, abrasive band 3, pressure boost subassembly 4, first carousel subassembly 5, second carousel subassembly 6, first drive assembly 7 and number of turns counter 8, and workstation 2, first carousel subassembly 5 and second carousel subassembly 6 all locate on the frame 1. The workbench 2 is used for placing a product to be tested. The grinding belt 3 is arranged above the workbench 2 and is used for contacting the surface of a product to be measured. The pressurizing assembly 4 is arranged above the grinding belt 3 and is used for pressing and holding the grinding belt 3 on the workbench 1 by means of self gravity. The first rotating disc assembly 5 comprises a first rotating shaft 51 and a first rotating disc 52, the first rotating disc 52 is sleeved on the first rotating shaft 51 and can rotate along with the rotation of the first rotating shaft 51, one end of the grinding belt 3 is wound on the first rotating disc 51, and when the first rotating disc 52 rotates, the grinding belt 3 can be wound on the second rotating disc 52. The second rotating disc assembly 6 is arranged between the first rotating disc assembly 5 and the workbench 2, the second rotating disc assembly 6 comprises a second rotating shaft 61 and a second rotating disc 62, the second rotating disc 62 is sleeved on the second rotating shaft 61, and the second rotating disc 62 is used for supporting the grinding belt 3, so that the grinding belt 3 is kept in a tensioning state in the working process. The first transmission assembly 7 comprises a first driving wheel 71, a first transmission belt 72 and a first driven wheel 73, the first driving wheel 71 is coaxially connected with the second rotating shaft 61, the first driving wheel 71 is connected with the first driven wheel 73 through the first transmission belt 72, and the first driven wheel 73 is coaxially connected with the first rotating shaft 51. The turn counter 8 is connected to the second shaft 61 for recording the number of turns of the second shaft 61.

The product to be measured is placed on the workbench 2, the grinding belt 3 is contacted with the ink layer on the surface of the product to be measured, and the grinding belt 3 passes through the second rotating disc 62 and is wound on the first rotating disc 52. When the second rotating shaft 61 is rotated, the second rotating disc 62 and the first driving wheel 71 both rotate along with the second rotating shaft 61, the first driven wheel 73 rotates along with the first driving wheel 71 under the action of the first transmission belt 72, and the first rotating shaft 51 rotates along with the first driven wheel 73, so that the first rotating disc 52 is driven to rotate. The synchronous rotation of the first turntable 52 and the second turntable 62 drives the abrasive belt 3 to move on the surface of the product to be measured. Under pressure holding effect at pressure boost subassembly 4, thereby grinding belt 3 and the surface production friction that awaits measuring make grinding belt 3 can inhale the printing ink of scraping the product surface that awaits measuring, under same test environment, pressure boost subassembly 4's gravity is certain, consequently gives 3 surperficial forces of exerting of grinding belt and is stable, also the friction dynamics between grinding belt 3 and the printing ink layer is stable, consequently under the condition that grinding belt 3 removed the same distance, it is unanimous to inhale the degree of scraping of printing ink layer. When the abrasion resistance of the ink layer is detected, whether the abrasion resistance of the ink layer is qualified can be judged only by setting the moving distance of the proper grinding belt 3, the whole judging process has stronger objectivity, and the probability of misjudgment is greatly reduced. Moreover, the number of turns of the second rotating shaft 61 is recorded by the turn counter 8, and the moving distance of the grinding belt 3 can be calculated quickly by the number of turns of the second rotating shaft 61 and the radius of the second rotating disc 62, so that the moving distance of the grinding belt 3 can be controlled by monitoring the number of turns of the second rotating shaft 61, and the friction strength of the ink layer can be controlled. In addition, the second rotating disk 62 can guide the movement of the grinding belt 3, and prevent the grinding belt 3 from shifting during the movement.

In particular, this printing ink wearability test machine still includes third carousel subassembly 9, the relative both sides of workstation 2 are located respectively to third carousel subassembly 9 and second carousel subassembly 6, third carousel subassembly 9 includes third pivot 91 and third carousel 92, third pivot 91 rotates and locates on the frame 1, third carousel 92 cover is located on third pivot 91, the other end of abrasive belt 3 is around connecing on third carousel subassembly 9, in the in-process that first carousel 52 rotated and is driven abrasive belt 3 and remove, third carousel 92 rotates along first carousel 52 under the drive of abrasive belt 3, realize unreeling the function from this, can avoid abrasive belt 3 directly to put the winding situation that appears on frame 1, make the removal process of abrasive belt 3 more smooth and easy.

In particular, the first rotating disk 52 and the third rotating disk 92 are respectively provided with an annular groove in the circumferential direction, and the width of the annular groove is equal to the width of the grinding belt 3, so that the grinding belt 3 can be wound on the first rotating disk 52 and the third rotating disk 92 neatly, and the grinding belt 3 can be prevented from shifting in the winding and unwinding processes.

In this embodiment, as shown in fig. 2, one end of the pressurizing unit 4 is rotatably connected to the frame 1, and the other end of the pressurizing unit 4 is pressed against the abrasive belt 3. So set up, only need rotate pressure boost subassembly 4, can realize the change of abrasive band 3 or the product that awaits measuring.

Specifically, the pressurizing assembly 4 includes a connecting member 41, a guide shaft 42 and a pressing member 43, the connecting member 41 is rotatably connected to the frame 1, the guide shaft 42 is connected to the connecting member 41, and the pressing member 43 is connected to the guide shaft 42 and is used for pressing and holding the abrasive belt 3 on the work table 2. In this embodiment, the connecting member 41 and the frame 1 may be rotatably connected by a pin or a pin.

The pressing member 43 may be a roller, so that the pressing member 43 does not scratch the polishing belt 3 when the polishing belt 3 passes through the surface of the product to be measured. It will be appreciated that the pressure holding member 43 may also be provided as a ball.

Further, pressure boost subassembly 4 still includes support piece 44 and adjusting weight 45, and support piece 44 cover is located on guiding axle 42, and can remove along guiding axle 42's axial, and adjusting weight 45 locates on support piece 44, through the adjusting weight of placing different weight on support piece 44, can adjust pressure boost subassembly 4's gravity, adjusts the frictional force degree between the printing ink layer of grinding belt 3 and the product that awaits measuring promptly to the detection demand of adaptation different conditions.

The pressurizing assembly 4 further comprises a first spring 47, the first spring 47 is sleeved on the guide shaft 42 and is arranged between the rack 1 and the support piece 44, when the external vibration is received, the impact of the support piece 44 and the adjusting weight 45 arranged on the support frame 44 on the surface of the grinding belt 3 and the product to be detected can be reduced by utilizing the buffering effect of the first spring 47, and the stability of the friction force of the pressurizing assembly 4 in the process of pressing the grinding belt 3 is ensured.

The pressure increasing assembly 4 further includes a limiting device 46, the limiting device 46 includes a bracket 461, a first roller 462 and a second roller 463, the bracket 461 is fixed on the guide shaft 42 and is disposed near the pressure holding member 43, the first roller 462 and the second roller 463 are respectively rotatably connected to the bracket 461, the first roller 462 and the second roller 463 are respectively disposed at two opposite sides of the pressure holding member 43, the axis of the first roller 462 is parallel to the axis of the second roller 463, the abrasive belt 3 sequentially passes between the first roller 462 and the pressure holding member 43 and between the second roller 463 and the pressure holding member 43, and the abrasive belt 3 respectively rolls and contacts with the first roller 461, the pressure holding member 43 and the second roller 462. First running roller 462 and second running roller 463 can play the guide effect to the removal of abrasive belt 3, and, before abrasive belt 3 passes through pressure holder 43, first running roller 462 can also play the effect of leveling abrasive belt 3 to reduce the influence of the roughness of abrasive belt 3 to the product printing ink layer wearing and tearing volume that awaits measuring, improve and detect the precision. It is understood that the axial width of the first roller 462 and the axial width of the second roller 463 are not smaller than the width of the abrasive belt 3.

As shown in fig. 3, the ink wear resistance testing machine further includes a driving device 10 and a second transmission assembly 11, the second transmission assembly 11 includes a second driving wheel 111, a second transmission belt 112 and a second driven wheel 113, the second driving wheel 111 is connected to the driving device 10, the second driving wheel is coaxially connected to an output shaft of the driving device 10, the second driving wheel 111 is connected to a second driven wheel 113 through the second transmission belt 112, and the second driven wheel 113 is coaxially connected to the second rotating shaft 61. Through setting up second transmission assembly 11, can realize drive arrangement 10 and the nimble in second carousel subassembly 6 space and place, avoid drive arrangement 10's output shaft direct with second pivot 61 be connected, help reducing this printing ink wearability test machine along the ascending distribution length of second pivot 61 axial.

In particular, the drive device 10 can be designed as a motor. The ink wear resistance testing machine also comprises a motor rotating speed regulator 16, the rotating speed of the motor can be regulated according to the actual transmission condition, and the friction speed of the grinding belt 3 can be regulated by regulating the rotating speed of the motor.

Further, this printing ink wearability test machine still includes fourth carousel subassembly 12, and the fourth carousel subassembly includes fourth pivot 121 and fourth carousel 122, and fourth carousel 122 cover is located on fourth pivot 121, and fourth pivot 121 rotates and locates on frame 1, and the axis of fourth pivot 121 is parallel to each other with the axis of second pivot 61, is equipped with clearance 13 between fourth carousel 122 and the second carousel 62, and this clearance 13 supplies abrasive belt 3 to pass through, and the width of clearance 13 can only hold abrasive belt 3 and pass through. The gap 13 can guide and level the abrasive belt 3, which is beneficial to the rolling process of the abrasive belt 3.

Further, a third roller 14 is arranged below the gap 13, and the third roller 14 is rotatably arranged on the frame 1, so that the movement of the grinding belt 3 can be guided, and the grinding belt 3 can smoothly enter the gap 13.

It can be understood that a fourth roller 15 is further arranged between the workbench 2 and the third roller 14, the fourth roller 15 is rotatably arranged on the rack 1 and can guide the movement of the grinding belt 3, the fourth roller 15 needs to be arranged according to the distance between the workbench 2 and the third roller 14, when the distance between the workbench 2 and the third roller is too long, the fourth roller 15 is arranged, and when the distance between the workbench 2 and the third roller is short, the fourth roller 15 can be omitted.

As shown in fig. 4 and 5, the second embodiment of the present invention is a modification of the first embodiment, in which the connecting member 41 is fixed on the frame 1, a through hole 411 is formed in the connecting member 41, the guide shaft 42 is movably inserted into the through hole 411 and is movable in the vertical direction in the through hole 411, and the pressing member 43 is connected to the guide shaft 42 and is used for pressing and holding the abrasive belt 3 on the table 2. The through hole 411 has a limiting effect on the guide shaft 42, and when the grinding belt 3 or a product to be detected needs to be replaced, the guide shaft 42 only needs to be moved towards the direction far away from the workbench 2.

In this embodiment, the pressurizing assembly 4 further includes a second spring 48, the second spring 48 is sleeved on the guiding shaft 42 and is disposed between the pressing member 43 and the frame 1, and the buffering effect of the second spring 48 can further reduce the vibration generated by the guiding shaft 42 in the vertical direction when the guiding shaft is vibrated from the outside, so as to further ensure the stability of the friction force between the grinding belt 3 and the ink layer of the product to be tested.

In conclusion, the ink wear resistance testing machine provided by the invention provides fixed and stable friction force to ensure the consistency of ink layer suction and scraping degrees under the same testing condition.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.

Claims

1. An ink abrasion resistance testing machine, comprising:

a frame;

2. The ink wear resistance testing machine according to claim 1, further comprising a third turntable assembly, wherein the third turntable assembly and the second turntable assembly are respectively disposed on two opposite sides of the working table, and the other end of the grinding belt is wound around the third turntable assembly.

3. The ink abrasion resistance tester according to claim 1, wherein one end of the pressurizing assembly is rotatably connected to the frame, and the other end of the pressurizing assembly is pressed against the grinding belt.

4. The ink wear testing machine of claim 3, wherein the pressurizing assembly comprises a connecting member, a guide shaft and a pressing member, the connecting member is rotatably connected to the frame, the guide shaft is connected to the connecting member, and the pressing member is connected to the guide shaft and is used for pressing and holding the abrasive belt on the worktable.

5. The ink wear testing machine of claim 4, wherein the pressurizing assembly further comprises an adjusting weight and a support member, the support member is sleeved on the guide shaft, and the adjusting weight is disposed on the support member.

6. The ink wear testing machine of claim 5, wherein the pressure increasing assembly further comprises a first spring, and the first spring is sleeved on the guide shaft and is disposed between the supporting member and the connecting member.

7. The ink wear resistance testing machine according to claim 4, wherein the pressure increasing assembly further includes a limiting device, the limiting device includes a bracket, a first roller and a second roller, the bracket is connected to the guide shaft, the first roller and the second roller are respectively rotatably connected to the bracket, the first roller and the second roller are respectively disposed on two opposite sides of the pressure holding member, an axis of the first roller and an axis of the second roller are parallel to each other, and the grinding belt sequentially penetrates between the first roller and the pressure holding member and between the second roller and the pressure holding member.

8. The ink wear resistance testing machine according to claim 1, wherein the pressurizing assembly includes a connecting member, a guide shaft, and a pressing member, the connecting member is fixed to the frame, a through hole is formed in the connecting member, the pressurizing assembly is inserted into the through hole and is movable in the through hole in a vertical direction, and the pressurizing assembly is pressed and held on the grinding belt.

9. The ink wear testing machine of claim 8, wherein the pressurizing assembly includes a guide shaft movably disposed in the through hole and a pressing member connected to the guide shaft for pressing the abrasive belt against the worktable.

10. The ink wear testing machine according to claim 1, further comprising a driving device and a second transmission assembly, wherein the second transmission assembly includes a second driving wheel, a second driven wheel and a second transmission belt, the second driving wheel is connected to the driving device, the second driving wheel is connected to the second driven wheel through the second transmission belt, and the second driven wheel is coaxially connected to the second rotating shaft.