CN108995477A - Anti-wear variable height buffer caster assembly - Google Patents

Abstract

The invention relates to an anti-abrasion high-buffering type caster assembly which comprises a caster and a caster connecting structure, wherein the caster connecting structure comprises a bottom plate, a plurality of height adjusting base plates and a pressing plate, the pressing plate is connected with the bottom plate through connecting bolts, the height adjusting base plates are connected with the bottom plate in a cushioning mode, the pressing plate is positioned on the uppermost base plate in a cushioning mode, the pressing plate is connected with the bottom plate through the connecting bolts, the pressing plate is positioned on the uppermost base plate in a cushioning mode, a central column is arranged on the pressing plate in a sleeved mode, a plurality of groups of bearings which are distributed along the circumferential direction of the connecting sleeve and supported on the circumferential surface of the central column in an up-and-down rolling mode are connected onto the connecting sleeve, the connecting sleeve. The invention has the advantages of wear resistance, vibration damping and adjustable height, and is used for solving the problems that the height of the conventional caster wheel cannot be adjusted and the vibration resistance effect is poor.

Description

Anti-wear variable height buffer caster assembly

technical field

The invention relates to equipment in the technical field of traditional Chinese medicine production, in particular to a wear-resistant variable-height buffer caster assembly.

Background technique

The original traditional Chinese medicines are basically decocted manually. In order to realize the automatic production of traditional Chinese medicines, those skilled in the art have designed automatic production equipment for traditional Chinese medicines. For the convenience of moving equipment, caster assemblies are usually provided on the equipment. The existing caster assembly has the following disadvantages: the height cannot be adjusted; the anti-vibration effect is poor.

Contents of the invention

The invention provides a wear-resistant variable-height buffer caster assembly, which is used to solve the problems that the existing caster height cannot be adjusted and the anti-vibration effect is poor.

The above technical problems are solved by the following technical solutions: a wear-resistant variable height buffer caster assembly, including casters and caster connection structure, the caster connection structure includes a bottom plate, a number of height adjustment pads on the bottom plate and The pressure plate on the uppermost backing plate, the pressure plate is connected with the bottom plate through the connecting bolts passing through the pressure plate and the height adjustment backing plate at the same time, the pressure plate is provided with a central column, and the central column is covered with a connecting sleeve , the connecting sleeve is connected with several sets of bearings distributed along the circumferential direction of the connecting sleeve and supported on the peripheral surface of the central column and rolling in the up and down direction, and the connecting sleeve is provided with a crosspiece located above the central column, The upper end surface of the center column is provided with a spring installation hole, and a damping spring stretching up and down is arranged in the spring installation hole, and the upper end of the damping spring is supported on the crosspiece, and the casters are connected to below the bottom plate. When in use, the present invention realizes installation by connecting the connecting sleeve with the supported object. The height of the caster assembly can be changed by changing the number of height adjustment backing plates to achieve height adjustment. The caster and the object supported by the caster are connected to two equally movable objects and supported by springs, so that vibration can be damped. The connecting sleeve is connected with the central column through the bearing, which can effectively reduce the wear between the connecting sleeve and the central column caused by vibration and lifting.

Preferably, the central column is a cylinder, the surface of the central column is provided with an anti-rotation plane extending in an up and down direction, and the bearing is supported on the anti-rotation plane. The bearing can also drive and prevent the rotation between the central column and the connecting sleeve.

Preferably, the connecting sleeve is composed of several convenient segments along the up-and-down direction, and the bearing is provided with a mounting shaft, and the mounting shaft is clamped between two adjacent segments. It is convenient to install and disassemble the bearing.

As a preference, the damping spring is pierced with a positioning rod, and the positioning rod is provided with a pressing plate resting on the upper end of the damping spring, and the connecting sleeve is provided with a crosspiece in the form of a central column. The shock-absorbing spring pre-tightening bolt abutted on the pressing plate is threadedly connected to the crosspiece. The cushion spring can be preloaded to adjust the stiffness.

As a preference, the positioning rod is fixedly connected with a compression plate that is slidingly and sealingly connected in the spring installation hole, and the compression plate isolates the sealed fat storage chamber and the spare oil storage chamber above the fat storage chamber in the spring installation hole. The grease storage bowl, the damping spring is located in the sealed grease storage chamber, the side wall of the spring mounting hole is provided with an oil outlet window through the sealed grease storage chamber, the oil outlet window is provided with a sealing plug and The sealing plug is driven to move toward the sealed grease storage chamber to close the window closing spring of the oil outlet window, and the compression plate is provided with a one-way valve on the compression plate that opens toward the sealed grease storage chamber. When in use, the grease is stored in the sealed grease storage chamber and the spare grease storage bowl at the same time. When the connecting sleeve is lowered due to vibration, the grease in the sealed grease storage chamber is transported to the outside of the connecting sleeve through the oil outlet window to realize the maintenance. Lubrication between the connecting sleeve and the central column, when the connecting sleeve rises, the grease in the spare grease storage bowl is replenished into the sealed grease storage chamber. It can produce automatic lubrication and automatic replenishment of grease when vibrating.

The present invention also includes a grease replenishing mechanism for adding grease to the spare grease storage bowl. The grease replenishing mechanism includes a grease nozzle and a grease gun, and the grease nozzle includes a grease nozzle housing and an outer rotor motor. There is a grease channel, and the grease channel passes through the lower side of the oil nozzle housing to form a grease outlet above the spare grease storage bowl, the outer rotor motor includes an inner stator and an outer rotor, and the oil nozzle housing is connected to the inner stator Above, the outer rotor is connected with an outlet plug for closing the grease outlet through the connecting shrapnel, and when the outlet plug is aligned with the grease outlet, it abuts against the grease outlet under the elastic force of the connecting shrapnel While sealing the grease outlet, the grease gun includes a barrel and a push plate that is slidingly sealed and connected in the barrel, and the push plate divides the barrel into an oil chamber and an air chamber, and the oil chamber is the same as the lubricating chamber. The inlet end of the grease channel is connected, and the air cavity is provided with an electric intake valve. Ability to re-grease the spare grease reservoir. Moreover, the grease nipple can prevent the grease remaining in the grease nipple from being exposed and solidified and clogged when the greasing is stopped. It is convenient to open and close the outlet plug, and it is not easy to lose the outlet plug.

As a preference, the outlet plug is a hollow structure, the inner tank of the outlet plug is filled with lubricating oil, and the upper end of the outlet plug is provided with a number of volatilization through holes and holes inside the air outlet when the outlet plug is closed in the grease outlet. A lubricating hole sealing plate made of a ferromagnet that covers the volatilization through hole. The lubricating hole sealing plate is provided with a sliding column pierced on the outlet plug, and the outlet plug is provided with a drive connected to the sliding column. The sealing plate of the lubricating hole is covered by the closing spring on the volatilization through hole, and the permanent magnet that absorbs the sealing plate of the lubricating hole to open the sealing plate of the lubricating hole is arranged in the grease channel. When the outlet plug is covered on the grease port, the volatilization through hole is opened to volatilize the lubricating oil and delay the solidification of the grease in the grease outlet. When the outlet plug is staggered with the lubricating grease port, the volatilization through hole can be automatically closed to prevent the volatilization of lubricating oil from causing environmental pollution.

Preferably, the grease replenishing mechanism further includes a control mechanism, the control mechanism includes a control unit connected to the crosspiece, a vertical rack, a gear meshed with the vertical rack, and detecting the number of turns of the gear The detection unit, the gear is connected to the central column through a one-way bearing, and when the detection unit detects that the gear rotates the set number of turns, the control unit makes the intake electric valve and oil nozzle open the set So that the grease in the oil chamber is added to the spare grease storage bowl through the grease nipple. It can automatically replenish grease according to the cumulative amount of vibration stroke.

The present invention also includes two connecting plates, the connecting sleeve is provided with a connecting convex ring extending along the circumferential direction of the connecting sleeve, the connecting convex ring is provided with threaded connection holes extending in the up and down direction, the connecting convex ring shown There is a straight section at both ends of the radial direction, the lower edge of the straight section is provided with a limit gap extending in the horizontal direction, the upper end of the connecting plate is provided with an upper limit slot, and the lower end is provided with a lower limit. Position card slot, the upper end of the connecting plate is connected to the end of the crosspiece through the upper connecting bolt and the upper limit card slot is sleeved at the end of the crosspiece, and the lower end of the connecting plate is connected to the straight section through the lower connecting bolt And the lower side wall of the lower limiting slot is set in the limiting gap, and the lower limiting slot is sleeved on the straight section. The connection is reliable.

Preferably, the caster includes a wheel frame and a disc-shaped plastic roller, the wheel frame includes a horizontal connecting rod and two vertical connecting rods whose upper ends are connected with the horizontal connecting rod, and the horizontal connecting rod is connected with the bottom plate Together, the disc-shaped plastic roller is located between the two vertical and horizontal connecting rods and connected together with the two vertical connecting rods through the axle. The structure is simple and practical.

The invention has the following advantages: the height can be adjusted; the anti-vibration effect is good; and the wear and tear generated when the vibration is raised and lowered is small.

Description of drawings

FIG. 1 is a schematic diagram of a three-dimensional state of Embodiment 1 of the present invention.

Fig. 2 is a schematic cross-sectional view of the first embodiment.

Fig. 3 is a partial schematic diagram of the second embodiment.

Fig. 4 is a schematic diagram when the oil nozzle is in an open state.

Fig. 5 is a schematic diagram when the grease nipple is closed and the lubricating hole sealing plate still covers the volatilization through hole.

Fig. 6 is a schematic diagram when the grease nipple is in a closed state and the lubricating hole sealing plate is in an open state.

In the figure: caster 1, wheel frame 11, horizontal connecting rod 111, vertical connecting rod 112, disc-shaped plastic roller 12, wheel shaft 121, base plate 21, height adjustment backing plate 2, pressure plate 23, connecting screw rod 24, oil nozzle 3, oil nozzle Shell 31, grease channel 311, grease outlet 312, grease inlet 313, outer rotor motor 32, inner stator 321, outer rotor 322, connecting shrapnel 33, outlet plug 34, volatilization through hole 341, lubrication hole sealing plate 342, Sliding column 343, cover spring 344, permanent magnet 35, central column 4, stop plane 41, spring mounting hole 42, sealed fat storage chamber 421, spare fat storage bowl 423, sealing plug 424, window closing spring 425, oil outlet Window 426, damping spring 43, positioning rod 44, pressing plate 45, damping spring preload bolt 46, connecting sleeve 5, bearing 51, upper segment 5-1, middle segment 5-2, lower segment 5 -3, locking bolt 53, connecting plate 54, upper limit card slot 541, lower limit card slot 542, connecting convex ring 55, threaded connection hole 551, straight section 552, limit notch 553, lower connecting bolt 554, upper Connecting bolt 555, crosspiece 56, compression plate 6, one-way valve 61 of compression plate, grease gun 7, gun barrel 71, oil chamber 711, air chamber 712, push plate 72, air intake electric valve 73, control mechanism 8 , a control unit 81 , a vertical rack 82 , a gear 83 , a detection unit 84 , an induction switch 841 , and a block 842 .

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment 1, referring to Fig. 1 and Fig. 2 , a wear-resistant variable height buffer caster assembly, including a caster 1 and a caster connection structure.

The caster 1 includes a wheel frame 11 and a disc-shaped plastic roller 12 . The wheel frame 11 includes a horizontal connecting rod 111 and two vertical connecting rods 112 whose upper ends are connected together with the horizontal connecting rod. The disc-shaped plastic roller 12 is located between the two vertical and horizontal connecting rods and is connected together with the two vertical connecting rods by the axle 121 .

The caster connection structure includes a bottom plate 21 , a number of height-adjusting backing plates 22 padded on the bottom plate, and a pressing plate 23 located on the topmost backing plate. Pressing plate is connected together with base plate by the connecting screw rod 24 that passes pressing plate and height adjustment backing plate simultaneously. The connecting bolts are directly threaded on the base plate.

A central column 4 is arranged on the pressing plate. A connecting sleeve 5 is sheathed on the central column. The connection sleeve is connected with 4 groups of bearing groups that are evenly distributed along the circumference of the connection sleeve and supported on the peripheral surface of the central column and roll in the up and down direction. Each group of bearings has two bearings 51 distributed along the up and down direction. The connection sleeve is composed of three segments 52 distributed along the up and down direction. The three segments are upper segment 5-1, middle segment 5-2 and lower segment 5-3. The bearing is provided with a mounting shaft. The installation shaft is clamped between two adjacent segments to realize the installation of the bearing. The three segments are locked together by locking bolts 53 . The connecting sleeve is also provided with two connecting plates 54 evenly distributed along the circumference of the connecting sleeve. The middle segment is provided with a connecting convex ring 55 extending along the circumferential direction of the connecting sleeve. A threaded connection hole 551 extending along the up and down direction is provided on the connecting convex ring. The object supported by the present invention realizes the connection with the present invention by being bolted in the threaded connection hole during use. A straight section 552 is provided at both radial ends of the connecting convex ring. A limiting notch 553 extending along the horizontal direction is provided on the lower edge of the straight section. The upper end of the connecting plate is provided with an upper limiting slot 541 , and the lower end is provided with a lower limiting slot 542 . The upper end of the connecting plate is connected to the end of the crosspiece 56 through the upper connecting bolt 555 and the upper limit card slot is sleeved on the end of the crosspiece. The lower end of the connecting plate is connected to the straight section through the lower connecting bolt 554 and the lower side wall of the lower limiting slot is passed through the limiting notch. The lower limit card slot is sleeved on the straight section. The crosspiece sits above the center column.

The central column 4 is a cylinder. Four anti-rotation planes 41 extending up and down are provided on the surface of the central column. The anti-rotation planes are evenly distributed along the circumference of the central column. The bearings on the four groups of bearing groups are supported on the four anti-rotation planes one by one. A spring installation hole 42 is provided on the upper end surface of the central column. A damping spring 43 that expands and contracts in the up and down direction is arranged in the spring mounting hole. A positioning rod 44 is pierced in the damping spring. The positioning rod is provided with a pressing plate 45 resting on the upper end of the damping spring. The shock-absorbing spring pre-tightening bolt 46 abutted on the pressing plate is threadedly connected to the crosspiece. The upper end of the damping spring is directly or indirectly (in this embodiment directly) supported on the crosspiece.

Embodiment two, the difference with embodiment one is:

Referring to FIG. 3 , FIG. 4 , FIG. 5 and FIG. 6 , the positioning rod 44 is fixedly connected with the compression plate 6 which is slidingly and sealingly connected in the spring installation hole 42 . The compression plate isolates a sealed fat storage chamber 421 and a spare fat storage bowl 423 above the fat storage chamber in the spring installation hole. The damping spring 43 is located in the sealed grease storage chamber and supported on the lower surface of the compression plate. The side wall of the spring mounting hole is provided with an oil outlet window 426 penetrating through the sealed grease storage chamber. The oil outlet window is provided with a sealing plug 424 and a window closing spring 425 that drives the sealing plug to move toward the sealed grease storage chamber to seal the oil outlet window. The compression plate is provided with a one-way valve 61 on the compression plate that opens toward the sealed fat storage chamber.

This embodiment also includes a grease replenishing mechanism for adding grease to the spare grease storage bowl. The grease supplement mechanism includes a grease nipple 3, a grease gun 7 and a control mechanism 8.

The oil nozzle 3 includes an oil nozzle housing 31 and an outer rotor motor 32 . A lubricating grease channel 311 is provided in the oil nozzle shell. The grease passage runs through the lower side of the nozzle housing to form a grease outlet 312 . The other end of the grease channel is provided with a grease inlet 313 . The outer rotor motor includes an inner stator 321 and an outer rotor 322 . The oil nozzle housing is connected to the inner stator. The outer rotor is connected with an outlet plug 34 for closing the grease outlet through a connecting shrapnel 33 . When the outlet plug is aligned with the grease outlet, it abuts against the grease outlet under the elastic force of the connecting shrapnel to seal the grease outlet. The outlet plug is a spherical hollow structure. The outlet plug inner tank contains lubricating oil. The upper end of the outlet plug is provided with a plurality of volatilization through holes 341 inside the air outlet when the outlet plug is closed in the grease outlet and a lubricating hole sealing plate 342 made of ferromagnets covering the volatilization through holes. The lubricating hole sealing plate is provided with a sliding post 343 pierced on the outlet plug. The outlet plug is provided with a cover spring 344 that is connected with the sliding column to drive the sealing plate of the lubrication hole to cover the volatilization through hole. The grease passage is provided with a permanent magnet 35 that absorbs the sealing plate of the lubrication hole so that the sealing plate of the lubrication hole is opened.

When it is necessary to open the outlet of the grease channel, the outer rotor motor drives the connecting shrapnel to rotate, so that the outlet plug and the outlet of the grease channel can be staggered. The lubricating hole sealing plate covers the volatilization through hole under the action of the sealing plate closing spring so that the lubricating oil cannot volatilize. When it is necessary to close the outlet of the grease passage, the outer rotor motor drives the connecting shrapnel to rotate, so that the outlet plug is aligned with the outlet of the grease passage, and the outlet plug covers the outlet of the grease passage under the elastic force of the connecting shrapnel. The permanent magnet attracts the sealing plate of the lubrication hole to overcome the elastic force of the closing spring of the sealing plate, so that the sealing plate of the lubrication hole loses the sealing effect on the volatilization through hole, and the lubricating oil volatilizes to prevent the residual grease in the grease outlet from being produced. The effect of curing blockage.

The grease outlet is located above the spare grease storage bowl 423 .

The grease gun 7 includes a barrel 71 and a push plate 72 that is slidably and sealingly connected in the barrel. The push plate divides the gun barrel into an oil chamber 711 and an air chamber 712. The oil chamber communicates with the inlet end of the grease channel, that is, the grease inlet 313. The air chamber is provided with an air intake electric valve 73 . Grease is housed in the oil chamber during use.

The control mechanism 8 includes a control unit 81, a vertical rack 82 connected to the crosspiece, a gear 83 engaged with the vertical rack, and a detection unit 84 for detecting the number of turns of the gear. The gears are connected to the center column by one-way bearings. The detection unit 84 includes an inductive switch 841 and a block 842 arranged on the gear. When the gear rotates to the block and the sensor switch is close to the closest distance, the sensor switch senses and inputs the signal to the control unit, and the sensor discloses that each time the block is sensed, the gear rotates a circle. The control unit is electrically connected with the induction switch, the external rotor motor and the electric valve for entering.

When in use, when the number of gear rotations detected by the detection unit reaches an integral multiple of the set number of turns, the control unit will open the intake electric valve and the oil nozzle for a set period of time so that the lubricating grease in the oil chamber will be added to the spare oil through the oil nozzle. fat storage bowl. For example, if the number of turns is set to 10, the oil nipple and the electric valve will be turned on for the set time and then closed when the gear rotates 10 times. When the gear turns 20 times, the oil nipple and the electric valve will be closed after the set time. The electric valve closes after opening for a set period of time, and so on.

Claims (10)

1. A wear-resistant variable height buffer caster assembly, including casters and caster connection structure, characterized in that, the caster connection structure includes a base plate, a number of height-adjusting backing plates attached to the bottom plate and a backing plate at the top The pressure plate on the top, the pressure plate is connected with the bottom plate through the connecting bolts passing through the pressure plate and the height adjustment backing plate at the same time, the pressure plate is provided with a central column, the central column is covered with a connecting sleeve, and the connecting sleeve There are several sets of bearing groups distributed along the circumferential direction of the connecting sleeve and supported on the peripheral surface of the central column and rolling in the vertical direction. The connecting sleeve is provided with a crosspiece located above the central column. The central column A spring installation hole is provided on the upper end surface of the spring installation hole, and a cushioning spring that expands and contracts in the up and down direction is provided in the spring installation hole. The upper end of the cushioning spring is supported on the crosspiece, and the casters are connected to the bottom plate below. 2. The wear-resistant variable height buffer caster assembly according to claim 1, wherein the central column is a cylinder, and the surface of the central column is provided with an anti-rotation plane extending in the up and down direction, and the The bearings in the bearing set are supported on said anti-rotation plane. 3. The wear-resistant variable height buffer caster assembly according to claim 1, characterized in that, the connecting sleeve is composed of several segments distributed along the upper and lower directions, and the bearings in the bearing group are provided with mounting shafts , the installation shaft is clamped between two adjacent segments. 4. The wear-resistant variable height buffer caster assembly according to claim 1, characterized in that, a positioning rod is pierced inside the damping spring, and a positioning rod resting on the upper end of the damping spring is provided on the positioning rod. As for the pressing plate, the connecting sleeve shown is provided with a crosspiece in the form of a central column, and the crosspiece is threadedly connected with a damping spring pre-tightening bolt abutting against the pressing plate. 5. The anti-wear and variable height buffer caster assembly according to claim 4, characterized in that, the positioning rod is fixedly connected with a compression plate that is slidably sealed and connected in the spring mounting hole, and the compression plate is A sealed fat storage chamber and a spare fat storage bowl located above the fat storage chamber are isolated in the spring installation hole, the damping spring is located in the sealed fat storage chamber, and a through hole is provided on the side wall of the spring installation hole. Seal the oil outlet window of the grease storage chamber, the oil outlet window is provided with a sealing plug and a window closing spring that drives the sealing plug to move toward the sealed grease storage chamber to seal the oil outlet window, and the compression plate is provided with a seal The one-way valve on the compression plate that opens the fat storage chamber. 6. The anti-wear and variable height buffer caster assembly according to claim 5, further comprising a grease replenishment mechanism for adding grease to the spare grease storage bowl, the grease replenishment mechanism includes a grease nipple and a Grease gun, the grease nozzle includes a grease nozzle housing and an outer rotor motor, a grease channel is provided in the grease nozzle housing, and the grease channel penetrates the lower side of the grease nozzle housing to form a grease outlet above the spare grease storage bowl, so The outer rotor motor includes an inner stator and an outer rotor, the nozzle shell is connected to the inner stator, and the outer rotor is connected with an outlet plug for closing the grease outlet through a connecting shrapnel, and the outlet plug is the same as the grease outlet. When the outlet is aligned, under the elastic force of the connecting shrapnel, it abuts against the grease outlet to seal the grease outlet. The grease gun includes a gun barrel and a push plate that is slidingly and sealingly connected in the gun barrel. The push plate divides the gun barrel into an oil chamber and an air chamber, the oil chamber communicates with the inlet end of the grease channel, and the air chamber is provided with an air intake electric valve. 7. The anti-wear and variable height buffer caster assembly according to claim 6, characterized in that, the outlet plug is a hollow structure, the inner tank of the outlet plug is filled with solvent, and the upper end of the outlet plug is provided with several When the outlet plug is closed in the grease outlet, the lubrication hole sealing plate is made of the volatilization through hole inside the air outlet and the ferromagnet covering the volatilization through hole, and the lubrication hole sealing plate is provided on the outlet plug Sliding column, the outlet plug is provided with a driving lubrication hole sealing plate connected with the sliding column to cover the cover spring on the volatilization through hole, and the grease channel is provided with an adsorption lubrication hole sealing plate so that the lubrication hole Permanent magnet for opening the cover plate. 8. The wear-resistant variable height buffer caster assembly according to claim 5, characterized in that, the grease replenishment mechanism further includes a control mechanism, and the control mechanism includes a control unit, a vertical tooth connected to the crosspiece The rack, the gear meshed with the vertical rack, and the detection unit that detects the number of turns of the gear, the gear is connected to the central column through a one-way bearing, and the detection unit detects that the gear rotates to a set value When the number of turns is counted, the control unit opens the electric intake valve and the oil nozzle for a set period of time so that the lubricating grease in the oil chamber is added to the spare grease storage bowl through the oil nozzle. 9. The wear-resistant variable height buffer caster assembly according to claim 1, further comprising two connecting plates, the connecting sleeve is provided with a connecting convex ring extending along the circumferential direction of the connecting sleeve, as shown The connecting convex ring is provided with threaded connection holes extending in the up and down direction, and the radial ends of the connecting convex ring shown are respectively provided with a straight section, and the lower end edge of the straight section is provided with a limiting gap extending in the horizontal direction , the upper end of the connecting plate is provided with an upper limit card slot, and the lower end is provided with a lower limit card slot, the upper end of the connecting plate is connected to the end of the crosspiece through an upper connecting bolt and the upper limit card slot is sleeved at the end of the crosspiece, The lower end of the connecting plate is connected to the straight section through the lower connecting bolt, and the lower side wall of the lower limit card slot is passed through the limit gap, and the lower limit card slot is sleeved on the straight section. paragraph. 10. The wear-resistant variable height buffer caster assembly according to claim 1, characterized in that, the caster includes a wheel frame and a disc-shaped plastic roller, and the wheel frame includes a horizontal connecting rod and two horizontal upper ends The vertical connecting rods connected together by the connecting rods, the horizontal connecting rods are connected together with the bottom plate, the disc-shaped plastic rollers are located between the two vertical and horizontal connecting rods and connected to the two vertical connecting rods through the axle Together.