TW201623125A - Lifting method applicable to tray conveyance and device thereof - Google Patents

Abstract

This invention provides a lifting method applicable to tray conveyance and a device thereof, in which a conveyance module of a conveyance device drive a plurality of trays forward; a first actuation part of a first stopper device is operable to drive a front lever to move upward for stopping forward conveyance of a tray; and a second actuation part of a second stopper device is operable to drive the back lever to move upward for stopping forward conveyance of another tray . Afterwards, a driving part of a lifting mechanism drives an ejection rod to raise to a predetermined position and push the tray to lift and thus separated from the conveyance module. After the front lever and the back lever are respectively driven down by the first actuation part of the first stopper device and the second actuation part of the second stopper device, the conveyance module drives said another tray forward. After the second actuation part of the second stopper device again drives the back lever upward to stop a subsequent trap moving forward, the driving part of the lifting mechanism drives the ejection rod down and allowing the tray to be placed on a surface of the conveyance module for performing conveyance. After the second actuation part of the second stopper device drives the back lever down, the conveyance module drives the subsequent tray to move forward thereby completing lifting and placing operations for tray conveyance.

Description

Pallet conveying lifting method and device thereof

The invention provides a lifting method and a device for the tray transportation, in particular, the conveying device can be used to drive the tray forward, and the first stopping device and the second stopping device cooperate with the electronic control system to prevent the stacking of the tray and make the lifting The mechanism can smoothly jack up or place the tray in the state where the conveying device is not stopped, or can speed up the production line speed without stopping the stable continuous conveying, and is convenient for mass production to achieve the effect of reducing the cost.

According to the current situation, the manufacturing industry is facing labor shortages and environmental awareness, labor and operating costs, and labor-intensive and technologically intensive pressures. Most of the industry responds to costs by means of industrial migration or the introduction of foreign workers. Rising, or using production line automation technology and fixture assistance to improve business quality and reduce costs, in order to reduce manpower, save manufacturing hours and increase production capacity.

Furthermore, in the automation of production lines in the manufacturing industry, the metropolis is applied to different stations within the plant for various processing processes such as processing, inspection, cleaning, assembly, quality control, warehousing and transportation, among which the production process is The workpiece to be processed is transported to the position of each station by means of a trolley and a conveyor belt of the conveying device, and the processing tool is reclaimed or refueled by a manual handling method or an industrial production line with a mechanical arm to facilitate processing of the machine tool. Processing all kinds of required components, products such as lathes, milling machines, planers, drilling machines or numerical control machines With (NC or CNC) and so on.

However, due to the needs of various processing processes, the above-mentioned workpieces must frequently carry out displacements and adjust alignment operations. Generally, a protective frame is attached to the workpiece or carried by a tray, and the workpiece is not passed through the protective frame or the tray. Scratches, cracks, or cracks or damage to the edge of the workpiece due to collisions may be caused by the conveyor to the location of each station, or the finished workpiece may be processed. Transfer to other stations for subsequent production processes, but when the conveyor belt transports multiple workpieces to each station, it must first suspend the transport before picking up or placing the workpiece, or by manual The method of transportation to pick up the workpiece and then place it on the storage rack in sequence. The intermittent conveying mode of the conveying device will delay the multiple working time of the rear workpiece, which is not only time-consuming, inefficient, and unfavorable for productivity. The lifting is easy, and the conveying device is easy to generate intermittent vibration when starting or stopping between the various workstations, and the workpiece is not stable. Transportation, or the possibility of offsets, collisions, scratches, cracks, etc., and the continuous start or stop of the conveyor, it is also easy to cause mechanical wear and reduce the overall service life, it is for those engaged in this industry The key to improving the research.

Therefore, in view of the above-mentioned problems and shortcomings, the inventors have collected and collected relevant data through multi-party evaluation and consideration, and have continuously tried and modified the years of R&D experience in this industry to design such a lifting method for pallet transportation. The invention patent for its device was born.

The main purpose of the present invention is that when the transport module of the transport device carries a plurality of trays, and the transport module drives the tray to the position of the jacking mechanism, the first actuating portion of the first stop device is activated. The stopper rises to block the advancement of the tray, and the second stop device The second actuating portion drives the rear bar to rise to block the other tray to advance, and the driving portion of the rear jacking mechanism drives the jacking rod to rise to the positioning, and pushes the tray to lift and separate the transport module, and waits for the first The first actuating portion of the stopping device and the second actuating portion of the second stopping device respectively drive the front bar and the rear bar to descend, and then the transport module drives the other tray to continue, when the second stop device is After the second actuating part again drives the rear bar to block the subsequent tray to the positioning, the driving part of the jacking mechanism will drive the jacking rod to descend, and place the tray on the surface of the conveying module for conveying, and wait for the second stop The second actuating part of the device drives the rear stop lever to descend, and then the transport module drives the subsequent tray to continue to advance, thereby completing the lifting and placing operation of the pallet transport, because the length of the transport device is preferably implemented as 70 meters and continuously operated. Do not stop, so that the jacking mechanism can use the first stop device and the second stop device to cooperate with the electronic control system to prevent the stacking of the tray, and smoothly lift or place the tray without stopping the conveying device. A subsequent pallet continuously transported without stopping the production line and the speed is accelerated, the production is facilitated to reduce the cost of the amount of utility.

1‧‧‧ delivery device

11‧‧‧Rack

111‧‧‧ side panels

112‧‧‧Support board

113‧‧‧ recess

12‧‧‧Transport module

121‧‧‧Conveyor belt

13‧‧‧First axle seat

14‧‧‧Second axle seat

15‧‧‧Third axle seat

2‧‧‧ jacking mechanism

21‧‧‧ Drive Department

210‧‧‧First air cylinder

211‧‧‧ Telescopic rod

2111‧‧‧First fixed plate

212‧‧‧First board

22‧‧‧Pushing rod

221‧‧‧ top board

222‧‧‧ positioning column

3‧‧‧First stop device

31‧‧‧First Operation Department

310‧‧‧Second air cylinder

311‧‧‧ Telescopic rod

3111‧‧‧Second fixed plate

312‧‧‧Second board

32‧‧‧Front bar

321‧‧‧First baffle

322‧‧‧ Elastomers

4‧‧‧Second stop device

41‧‧‧Second Mobilization Department

410‧‧‧third pneumatic cylinder

411‧‧‧ Telescopic rod

4111‧‧‧ third fixed plate

412‧‧‧ third board

42‧‧‧ Rear bar

421‧‧‧second baffle

422‧‧‧ Elastomers

5‧‧‧Tray

51‧‧‧Base

511‧‧‧ Missing slot

512‧‧‧ docking holes

52‧‧‧ accommodating slots

6‧‧‧Workpiece

The first figure is a three-dimensional appearance of the present invention.

The second figure is a side view of the invention.

The third figure is a flow chart of the steps of the present invention.

The fourth figure is a schematic view of the operation of the tray of the present invention.

The fifth figure is a schematic view of the action when the front bar is raised.

The sixth figure is a plan view of the front bar of the present invention when it is blocked.

The seventh figure is a schematic view of the action when the rear bar is raised.

The eighth figure is a schematic view of the action when the jacking mechanism of the present invention lifts the tray.

The ninth diagram is a schematic view of the action of the front and rear levers of the present invention as they descend.

The tenth figure is a schematic view of the action when the rear stop lever is raised.

The eleventh figure is a schematic view of the action when the lifting mechanism of the present invention places the tray.

The twelfth figure is a schematic view of the action when the rear stop lever of the invention is lowered.

In order to achieve the above objects and effects, the technical means and constructions of the present invention will be described in detail with reference to the preferred embodiments of the present invention.

Please refer to the first and second figures, which are respectively a perspective view and a side view of the present invention. As is clear from the figure, the present invention includes a conveying device 1, a lifting mechanism 2, and a first stopping device. 3 and a second stopping device 4, wherein: the conveying device 1 has a frame 11 with opposite side plates 111 at two sides of the frame 11, and at least two sides of the two side plates 111 are combined along the length direction. An upwardly projecting support plate 112, and each of the support plates 112 is formed with a stepped recess 113 adjacent to the side plate 111, and the frame 11 is disposed between the two side plates 111 to be provided with a driveable tray 5 or The workpiece 6 (shown in Figures 6 and 7) carried on the tray 5 is displaced by the transport module 12, and the transport module 12 has a conveyor belt 121 and a roller on the support plate 112, which can be powered by the power unit. The chain on the motor-driven transmission mechanism and the roller-driven conveyor belt 121 are disposed on the support plate 112 in a cyclical displacement. The two side plates 111 of the frame 11 are vertically coupled to each other. The plurality of first axle seats 13 are opposite to the upright shape, and are divided on the front and rear sides of the first axle seat 13 The second axle seat 14 and the third axle seat 15 are oppositely coupled to each other in the longitudinal direction.

However, the above-mentioned tray 5 is a base 51 having a rectangular shape, and the base 51 is internally formed with at least one receiving groove 52 for positioning the workpiece 6, and longitudinally formed at four corners of the periphery of the base 51, respectively. The plurality of docking holes 512 are respectively recessed from the bottom surface of the base 51 adjacent to the notch 511, and the width of the base 51 of the tray 5 is larger than the width of the conveyor belt 121, so that the tray 5 can be placed on the tray 51. The conveyor belt 121 is on the horizontal surface, and the base 51 extends from the two sides of the conveyor belt 121 to form a suspended state. Because the structure of the tray 5 is designed in many ways, it can also be changed according to the actual application, so that the tray 5 carries the workpiece. 6 is placed on the surface of the conveyor belt 121 for continuous conveyance.

The jacking mechanism 2 is disposed at a center below the two side plates 111 of the frame 11 to be provided with a driving portion 21, and a telescopic rod 211 is disposed at a side of the first pneumatic cylinder 210 of the driving portion 21, so that the first The fixing plate 2111 longitudinally couples the end of the telescopic rod 211 to the center of the bottom of the frame 11, and the first pneumatic cylinder 210 of the driving portion 21 is connected with a first frame 212 extending out to the outer side of the frame 11. And a plurality of ejector pins 22 inserted into the first axle seat 13 for vertical sliding displacement are longitudinally disposed at four corners on the surface of the first shelf 212, and the ends of the ejector pins 22 on the two sides respectively The top plate 221 is disposed on the two sides of the concave portion 113 and the conveyor belt 121, and the positioning post 222 is disposed on the front and rear sides of the top plate 221. When the driving portion 21 drives the telescopic rod 211 to drive When the first plate 212 and the push rod 22 are moved up, the positioning posts 222 on the top plate 221 can be respectively engaged in the mating holes 512 of the base 51 of the tray 5 for auxiliary positioning, and pushed to the top of the bottom surface of the tray 5. The action of ascending.

The first stopping device 3 is located at the front of the jacking mechanism 2 and is provided with a first actuating portion 31, and is provided with a telescopic expansion at a side of the second pneumatic cylinder 310 of the first actuating portion 31. The rod 311 can longitudinally couple the end of the telescopic rod 311 to the center of the bottom of the frame 11 by using the second fixing plate 3111, and the second pneumatic cylinder 310 of the first actuating portion 31 is connected to extend to the frame 11 a second frame 312 at the outer side of the second frame 312, and a plurality of front blocking bars 32 penetrating in the second shaft seat 14 for vertical sliding displacement at the two sides of the second frame plate 312, and the front ends of the front blocking bars 32 The first first baffle 321 is arranged to be vertically displaced at the two sides of the concave portion 113 and the conveyor belt 121, and the elastic body 322 which is rubber or silicone is disposed at the inner side of the two first baffles 321 respectively. When the first actuating portion 31 drives the telescopic rod 311 to drive the second frame 312 and the front bar 32 to move upward, the elastic body 322 on the first baffle 321 can be raised above the horizontal surface of the conveyor belt 121, and The notch 511 of the base 5 of the tray 5 abuts against the elastic body 322 to block the action.

The second stopping device 4 is disposed at the rear of the jacking mechanism 2 to provide the second actuating portion 41, and the telescopic rod 411 is disposed at the side of the third pneumatic cylinder 410 of the second actuating portion 41. The third fixing plate 4111 longitudinally couples the end of the telescopic rod 411 to the center of the bottom of the frame 11, and the third pneumatic cylinder 410 of the second operating portion 41 is connected to the third portion extending to the outer side of the frame 11 The frame plate 412 is disposed at a plurality of longitudinal sides of the third frame plate 412 at a longitudinal direction thereof, and a plurality of rear blocking bars 42 are inserted into the third shaft seat 15 for sliding up and down, and the ends of the rear blocking bars 42 are respectively coupled to the concave portion. And a lateral second baffle 421 which is vertically displaced at the two sides of the conveyor belt 121, and an elastic body 422 which is rubber or silicone at the opposite inner side of the second second baffle 421, respectively, when the second actuating portion 41 When the driving telescopic rod 411 drives the third frame 412 and the rear bar 42 to be displaced upward, the elastic body 422 on the second baffle 421 can be raised above the horizontal surface of the conveyor belt 121, and the base 51 of the other tray 5 can be driven. The missing groove 511 abuts against the elastic body 422 to block the action.

Furthermore, the transport module 12 of the transport device 1 is preferably implemented with a conveyor belt 121 and a roller. However, in practical applications, a plurality of rollers or a conveyor chain and a combination thereof may be used to drive the displacement of the tray 5 and the workpiece 6, and the top. The driving portion 21 of the lifting mechanism 2, the first operating portion 31 of the first stopping device 3 and the second operating portion 41 of the second stopping device 4 can utilize the first pneumatic cylinder 210, the second pneumatic cylinder 310, and the third The pneumatic cylinder 410 drives the push rod 22, the front shift lever 32 and the rear shift lever 42 to move up or down respectively, and can also drive the gear set, the rack, the connecting rod and the chain on the transmission mechanism by using the motor and the hydraulic cylinder. The ejector lever 22, the front ram 32 and the rear dam 42 are respectively driven to move up or down; and the power unit (not shown) of the conveying device 1 and the driving unit 21 of the jacking mechanism 2 are respectively The first actuating portion 31 of the stop device 3 and the second actuating portion 41 of the second stopping device 4 are electrically connected to an electronic control system (not shown), and the parameter setting can be performed by the electronic control system. Drive and operation control, instant detection and status diagnostics, and controller communication for the overall system For the normal operation, all the simple modifications and equivalent structural changes made by the use of this manual and the contents of the drawings shall be included in the scope of the patent of this creation and shall be combined with Chen Ming.

Please refer to the third, fourth, fifth, sixth, seventh, eighth and ninth diagrams, which are respectively the flow chart of the steps of the present invention, the action diagram when the tray is transported, the action diagram when the front shift lever is raised, and the blocking action. The top view, the action diagram when the rear bar is raised, the action diagram when the jacking mechanism jacks up the tray, and the action diagram of the front bar and the rear bar are lowered, as can be clearly seen from the figure, when the tray is transported by the present invention The lifting method includes the following steps: (101) the conveying module 12 of the conveying device 1 carries a plurality of trays 5, and the conveying module 12 drives the tray 5 to advance, and the first step of the jacking mechanism 2 The stopper device 3 drives the front stopper lever 32 to advance the blocking tray 5 by the first actuating portion 31.

(102) The second stopper device 4 behind the jacking mechanism 2 drives the rear lever 42 to move forward to block the other tray 5 from advancing by the second actuating portion 41.

(103) The jacking mechanism 2 drives the jacking rod 22 to rise by the driving portion 21, and pushes the tray 5 to perform lift separation from the transport module 12.

(104) The first actuating portion 31 of the first stopping device 3 and the second actuating portion 41 of the second stopping device 4 respectively drive the front bar 32 and the rear bar 42 to fall back to the original position, and the conveying module 12 drives the other tray 5 to continue.

(105) The second actuating portion 41 of the second stopping device 4 again drives the rear bar 42 to block the subsequent tray 5 from advancing, and the driving portion 21 of the jacking mechanism 2 drives the jacking rod 22 to descend and the tray 5 to be placed thereon. The transport module 12 is transported on the surface.

(106) The second actuating portion 41 of the second stopping device 4 again drives the rear bar 42 to fall back to the original position, and the transport module 12 drives the subsequent tray 5 to continue to advance, thereby completing the lifting and setting of the tray 5 Put the action.

It can be clearly seen from the above-mentioned implementation steps that the transport module 12 of the transport device 1 of the present invention carries a plurality of trays 5, and the power belt (not shown) drives the conveyor belt 121 to drive the tray 5 forward. When the displacement to the position of the jacking mechanism 2 is 5, the first actuating portion 31 of the first stopping device 3 is activated to drive the front bar 32 to be displaced in the lower direction of the horizontal surface of the conveyor belt 121, and rise to the front bar 32 to The positioning can prevent the front side of the tray 5 from abutting against the elastic body 322 of the first baffle 321 and then block the advancement, and then the second actuating portion 41 of the second stopping device 4 is driven by the rear stop lever 42 at the conveyor belt 121. The horizontal surface is displaced upward and downward, and the rear bar 42 is raised to the position, so that the other tray 5 at the rear can be abutted against the elastic body 422 of the second baffle 421 to block the advancement to prevent the collision with the front tray. 5 caused by collision or damage to the workpiece 6.

After the second stop device 4 is raised to the position, the driving portion 21 of the jacking mechanism 2 is activated to displace the push rod 22 in the lower direction of the horizontal surface of the conveyor belt 121, and the push rod 22 is pushed on the push rod 22 Ascending to the positioning, while pushing the top plate 221 to perform the lifting action on the bottom surface of the tray 5, the tray 5 is separated from the conveyor belt 121 of the transport module 12, and then the first actuating portion 31 of the first stop device 3 is formed. The second actuating portion 41 of the second stopping device 4 is respectively driven to move the front bar 32 and the rear bar 42 in the lower direction of the horizontal surface of the conveyor belt 121, and is lowered by the front bar 32 and the rear bar 42. Returning to the original position, the other tray 5 can be driven to continue by the transport module 12. Since the length of the transport device 1 is preferably 70 meters and the continuous operation is not stopped, the jacking mechanism 2 can be utilized. A stop device 3 and the second stop device 4 cooperate with the electronic control system to prevent the tray 5 from being stacked, or the trays 5 collide with each other or the workpiece 6 is damaged, and the tray 10 is smoothly lifted in a state where the conveying device 1 is not stopped. So that the subsequent tray 5 can be continuously conveyed without stopping, so as to facilitate The pallet 5 can be transported to significantly reduce the working time.

Please also refer to the tenth, eleventh, and twelfth drawings, which are schematic diagrams of the action when the rear bar is raised, the action diagram when the jacking mechanism is placed on the tray, and the action diagram when the rear bar is lowered. It can be clearly seen that when the jacking mechanism 2 completes the action of lifting the tray 5, the electronic control system drives the robot arm (not shown) to take the workpiece 6 carried on the tray 5. And placed on the processing tool (not shown) to carry out the subsequent processing of the workpiece 6, such as milling, drilling, grinding or cleaning, and after the machining tool finishes the workpiece 6, the robot arm can be used. After the workpiece 6 is taken out, it is placed in the tray 5 to automatically complete the action of reclaiming or refueling.

Then, the second actuating portion 41 of the second stopping device 4 will again drive the rear bar 42 to the position, and the rear tray 5 abuts against the rear bar 42 to block the advancement to prevent the tray 5 from being stacked. Then, the driving portion 21 of the jacking mechanism 2 drives the jacking rod 22 to fall back to the original position, and the tray 5 is smoothly placed on the surface of the conveyor belt 121 of the conveying module 12 by the top plate 221 of the jacking rod 22, And after the positioning post 222 on the top plate 221 is separated from the mating hole 512 of the tray 5, the tray 5 can be continuously transported to the waiting station for the next station, and the second actuating portion of the second stop device 4 is 41 will also drive the rear stop lever 42 to return to the original position again, and the transport module 12 will drive the subsequent tray 5 to continue to advance, so that the subsequent tray 5 can be continuously transported without stopping, and the speed of the production line can be accelerated by the stable conveyance. It is convenient for mass production to reduce the cost.

The above detailed description is intended to be illustrative of a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and other equivalents and modifications may be made without departing from the spirit of the invention. Changes are intended to be included in the scope of the patents covered by the present invention.

In summary, the lifting method and the device for the above-mentioned tray transportation of the present invention can truly achieve the effect and purpose, and therefore the invention is an invention with excellent practicability, which is in accordance with the application requirements of the invention patent, and is proposed according to law. To apply, I hope that the trial committee will grant this case as soon as possible to protect the inventor's hard work. If there is any doubt in the bureau, please do not hesitate to give instructions, the inventor will try his best to cooperate, and feel really good.

Claims (9)

A lifting method for pallet transportation utilizes a conveying device, a lifting mechanism, a first stopping device and a second stopping device, and includes the following steps: (a) the conveying module of the conveying device carries a plurality of trays And the transport module drives the tray to advance, and the first stop device in front of the jacking mechanism drives the front bumper to block the advancement of the tray by the first actuating portion; (b) the second stop device behind the jacking mechanism utilizes The second actuating part drives the rear bar to rise to block the other tray to advance; (c) the jacking mechanism drives the jacking rod to rise by the driving part, and pushes the tray to lift and form a separation from the conveying module; (d) the first stopping device The first actuating portion and the second actuating portion of the second stopping device respectively drive the front bar and the rear bar to fall back to the original position, and the transport module drives the other tray to continue; (e) the second stop The second actuating portion of the device again drives the rear stop bar to block the subsequent tray advancement, and the driving portion of the jacking mechanism drives the push rod to descend and the tray is placed on the surface of the transport module for transport; (f) the second stop Second act of the device again After moving lever decline to return to its original position by the transport module to drive subsequent tray to move forward, we will complete lifting of the pallet conveyor and placed in operation. A lifting device for pallet transportation includes a conveying device, a lifting mechanism, a first stopping device and a second stopping device, wherein: the conveying device has opposite side plates at two sides of the frame. And between the two side panels a transport module capable of driving a displacement of a workpiece carried on a preset tray or a tray; the jacking mechanism is disposed at a lower portion of the rack with a driving portion, and is coupled to the driving portion at a side of the transport module The driving unit drives the upper and lower displacements to jack up or place the plurality of jacks of the preset tray; the first stopping device is disposed at the front of the jacking mechanism to be provided with the first actuating portion, and is disposed on the first actuating portion The plurality of front blocking bars are disposed at the side edges of the conveying module and are movable by the first actuating portion to block the advancement of the preset tray; the second stopping device is disposed at the rear of the jacking mechanism. The actuating portion is coupled to the second actuating portion with a plurality of rear blocking bars at the two side edges of the transport module and for the second actuating portion to move up and down to block the advancement of the other preset tray. The lifting device for pallet transportation according to claim 2, wherein the inner side of the two side plates of the conveying device frame is combined with at least one supporting plate protruding upward, and adjacent to the side plate on two sides of the supporting plate. A recess is formed at the portion, and the transport module has a conveyor belt on the support plate for driving the displacement of the preset tray. The lifting device for pallet transportation according to claim 3, wherein the driving portion of the jacking mechanism has a first pneumatic cylinder, and is provided at a side of the first pneumatic cylinder to be coupled by the first fixing plate. a telescopic rod at the bottom of the rack, and the first air cylinder is connected to the first frame extending to the outer side of the frame 2, and the end of the jacking rod provided on the first frame is respectively combined with the recessed portion The top plate for the upper and lower displacement. The lifting device for pallet conveying according to claim 3, wherein the first actuating portion of the first stopping device has a second pneumatic cylinder and is available at a side of the second pneumatic cylinder. The second fixing plate is coupled to the telescopic rod at the bottom of the rack, and the second pneumatic cylinder is connected with a delay The second shelf extending to the outer side of the frame 2 is coupled to the first baffle at the end of the second shelf to be coupled to the first baffle at the recess. The lifting device for pallet transportation according to claim 5, wherein the first baffle of the first stopping device and the first baffle of the front blocking bar are opposite to the inner side for being blocked by the front side of the preset tray. Elastomer. The lifting device for pallet transportation according to claim 3, wherein the second actuating portion of the second stopping device has a third pneumatic cylinder and is available at a side of the third pneumatic cylinder. The third fixing plate is coupled to the telescopic rod at the bottom of the rack, and the third pneumatic plate is connected with a third frame extending to the outer side of the frame, and then the ends of the rear bar are respectively combined with the third plate. There is a second baffle located at the recess for up and down displacement. The lifting device of the tray conveying according to the seventh aspect of the invention, wherein the second baffle of the second stop device has a second baffle opposite to the inner side for being placed at the front side of the other preset tray Block the elastomer. The lifting device for pallet transportation according to the second aspect of the invention, wherein the side edges of the two side plates of the conveying device frame are respectively vertically coupled with the jacking rod for the jacking mechanism for vertical sliding displacement. a plurality of first axle seats, and longitudinally coupled with the front bar of the first stopping device and the rear bar of the second stopping device for vertical sliding displacement at the front and rear sides of the first axle seat Two-axis seat and third shaft seat.