A telescopic hoist with weighing structure

Abstract

The present invention relates to the technical field of elevators, and specifically discloses a telescopic elevator with a weighing structure, including an inclined support frame, a frame and a hopper, wherein the frame is slidably mounted on the inclined surface of the inclined support frame, a transmission assembly is arranged between the frame and the hopper, a weighing assembly for weighing the weight of the material in the hopper is arranged on the inclined support frame, a driving assembly for driving the frame to slide is arranged in the inclined support frame, a flip support assembly is arranged between the hopper and the frame, a limiting assembly for assisting the support frame is arranged at the top of the inclined support frame, and the frame includes two I-shaped steels and two connecting frames that are fixedly connected end to end, and a second roller is installed on the side away from the two I-shaped steels. The present invention has a telescopic lifting path, which is convenient for vehicles or workers to pass through, convenient for use in narrow spaces, and convenient for quantitative transportation of materials.

Description

Technical Field

[0001] The invention relates to the technical field of hoists, and in particular to a telescopic hoist with a weighing structure. Background Art

[0002] Elevators include hoists. Both hoists and elevators are conveying equipment that can transport materials from one place to another. Hoists are large-scale mechanical equipment that transports materials by changing potential energy. They are widely used in logistics, warehousing, industry and other fields.

[0003] When using existing elevators in some relatively small spaces, such as roadsides and bridge heads, the outer support frame structure is generally fixed, which makes it inconvenient for vehicles or workers to pass under some support frames. In addition, the amount of material transported is not accurate enough, and the materials need to be manually re-weighed later, which makes it inconvenient to use. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a telescopic hoist with a weighing structure, which can overcome the technical defects.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A telescopic hoist with a weighing structure, comprising an inclined support frame, a frame and a hopper, wherein the frame is slidably mounted on an inclined surface of the inclined support frame, a transmission assembly is arranged between the frame and the hopper, a weighing assembly for weighing the weight of the material in the hopper is arranged on the inclined support frame, a driving assembly for driving the frame to slide is arranged in the inclined support frame, a flip support assembly is arranged between the hopper and the frame, and a limit assembly for assisting the support frame is arranged at the top of the inclined support frame;

[0007] The frame comprises two I-shaped steels and two connecting frames which are fixedly connected end to end. Second rollers are installed on the sides of the two I-shaped steels which are far away from each other, and the second rollers match the inner inclined rails of the diagonal support frame. First rollers are fixedly installed in the inner wall inclined rails on the opposite sides of the diagonal support frame, and the first rollers match the adjacent I-shaped steels.

[0008] The transmission assembly includes a sprocket and a chain, the two sprockets are rotatably mounted on the opposite sides of the two connecting frames, the chain is wound between the two sprockets, a clamping block and a limit seat are fixedly mounted on the side wall of the chain, the clamping block is connected to the hopper through a flip support assembly, and the limit seat is fixedly connected to the diagonal support frame;

[0009] The hopper comprises a first bucket shell and a second bucket shell, wherein the first bucket shell and the second bucket shell are slidably connected in a vertical direction through four sets of limiting structures, and a weighing assembly is arranged at the bottom of the limiting structure.

[0010] Preferably, the limiting structure comprises a support block, which is fixedly mounted on the side wall of the second bucket shell by screws, and two limiting holes are provided on opposite sides of the first bucket shell, and the support block is slidably mounted in the limiting holes along the vertical direction.

[0011] Preferably, the bottom wall of the discharge port of the first bucket shell is provided with two blocks, and the bottom wall of the discharge port of the second bucket shell is provided with two assembly blocks, and the top ends of the blocks are provided with assembly grooves, and the assembly blocks match the assembly grooves of the blocks.

[0012] Preferably, the weighing assembly includes a U-shaped plate, which is located above the diagonal support frame, and four pressure sensors are installed at the bottom end of the U-shaped plate. The force-bearing screws of the pressure sensors are connected to supporting feet. Four square columns are arranged at the top of the U-shaped plate, and a hydraulic cylinder is arranged at the top of the square column. The piston rod of the hydraulic cylinder matches the adjacent support block.

[0013] Preferably, the driving assembly includes a servo motor, a driving shaft is passed through and rotatably installed between the opposite sides of the diagonal support frame, the driving shaft is keyed to two gears, the bottom ends of the two I-shaped steel materials are provided with racks, the racks are meshing with the gears, a worm gear transmission box is provided on the outer wall of one side of the diagonal support frame, the servo motor is fixedly installed on the outer wall of one side of the diagonal support frame, and the output shaft of the servo motor is fixedly connected to the input shaft of the worm gear transmission box through a coupling.

[0014] Preferably, the limiting assembly comprises a limiting shaft, the limiting shaft passes through and is rotatably mounted on opposite sides of the top of the diagonal support frame, the limiting shaft is sleeved with two limiting wheels, and the limiting wheels match the I-shaped steel.

[0015] Preferably, the flip support assembly includes an H-shaped frame, which is fixedly installed at the bottom end of the first bucket shell, and support plates are rotatably installed on the opposite sides of the H-shaped frame, and a third roller is provided on the side away from each other of the two support plates, and the third roller matches the inner side slide rail of the adjacent I-shaped steel, and a connecting rod is fixedly installed between the two support plates, and two arc blocks are provided at the bottom end of the H-shaped frame, and the arc blocks match the support sleeve, and a stopping structure is provided between the flip support assembly and the frame.

[0016] Preferably, the stopping structure includes a support sleeve and a stop block, the support plate is composed of two square plates that are integrally arranged and have flush top ends, the connecting frame located above is rotatably installed with two support sleeves via a rotating shaft, and the stop block is fixedly installed at the bottom end of the H-shaped frame, and the stop block matches the support sleeve.

[0017] The beneficial effects of the present invention are:

[0018] 1. By setting a driving assembly, a transmission assembly and a flip support assembly, the beneficial effect that can be obtained is that the frame includes two I-shaped steels and two connecting frames that are fixedly connected end to end, and the second roller is installed on the side away from the two I-shaped steels, and the second roller matches the inner side inclined rail of the diagonal support frame. The first roller is fixedly installed in the inner wall inclined rails on the opposite sides of the diagonal support frame, and the first roller matches the adjacent I-shaped steel. Two sprockets are rotatably installed on the opposite sides of the two connecting frames, and the chain is wound between the two sprockets. A clamp block and a limit seat are fixedly installed on the side wall of the chain. The clamp block is connected to the hopper through a flip support assembly. The limit seat is fixedly connected to the diagonal support frame. A drive shaft is penetrated and rotatably installed between the two opposite sides of the diagonal support frame. The drive shaft key is connected to two gears. Racks are arranged at the bottom ends of the two I-shaped steels. The racks and the gears are meshed. A worm gear transmission box is arranged on the outer wall of one side of the diagonal support frame. The servo motor is fixedly installed on the outer wall of one side of the diagonal support frame. The output shaft of the servo motor is fixedly connected to the input shaft of the worm gear transmission box through a coupling.

[0019] The servo motor drives the worm gear transmission box to drive the drive shaft to rotate, the gear and rack are meshed for transmission, the I-shaped steel and the connecting frame rise or fall synchronously with the rack in the diagonal support frame, the first roller and the second roller cooperate with the I-shaped steel and the diagonal support frame, and have a rolling limiting effect. When the frame rises, the distance between the first roller and the adjacent second roller decreases, and when the frame descends, the distance between the first roller and the adjacent second roller increases. During the movement of the frame, since the limit seat and the diagonal support frame are relatively fixed, the chain is cooperated to drive the two sprockets to rotate, and the clamping block slides relative to the frame. The flip support assembly slides synchronously with the clamping block, and the two third rollers roll in the slide rails of the two I-shaped steels. When the block resists the support sleeve, the H-shaped frame and the hopper flip over to pour out the material, and the hopper is reset by the driving assembly and the transmission assembly. It has a telescopic lifting path, which is convenient for vehicles or workers to pass through, and is convenient for use in narrow spaces.

[0020] 2. By setting the hopper and the weighing assembly, the beneficial effect that can be obtained is that the hopper includes a first bucket shell and a second bucket shell, the first bucket shell and the second bucket shell are slidably connected in the vertical direction through four sets of limit structures, the U-shaped plate is located above the diagonal support frame, four pressure sensors are installed at the bottom end of the U-shaped plate, the force-bearing screws of the pressure sensors are connected to the support feet, four square columns are arranged at the top end of the U-shaped plate, a hydraulic cylinder is arranged at the top end of the square column, and the piston rod of the hydraulic cylinder matches the adjacent support block;

[0021] When the material is put into the second bucket shell, the four hydraulic cylinders of the controller respectively support the adjacent support blocks, and the support blocks slide upward in the limit holes. The second bucket shell slides synchronously in the first bucket shell. Four sets of pressure sensors and support feet cooperate with U-shaped plates to weigh the materials, which is convenient for quantitative transportation of materials.

[0022] 3. By setting the limit assembly, the beneficial effect that can be obtained is that the limit shaft penetrates and is rotatably installed on the top two sides of the diagonal support frame, and the limit shaft is sleeved with two limit wheels, and the limit wheels match the I-shaped steel;

[0023] When the frame is rising or falling, the two limiting wheels respectively provide auxiliary support to the two I-shaped steels to improve the stability of the elevator. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 It is the installation structure diagram of the driving assembly in the present invention;

[0027] Figure 3 It is the lifting state diagram in the present invention;

[0028] Figure 4 This is a diagram of the installation structure of the limit assembly in the present invention;

[0029] Figure 5 It is the installation structure diagram of the frame and the transmission assembly in the present invention;

[0030] Figure 6 An exploded view of the transmission assembly and the frame of the present invention;

[0031] Figure 7 This is a structural diagram of the installation of the hopper in the present invention;

[0032] Figure 8 It is a diagram of the overturning state of the hopper in the present invention;

[0033] Fig. 9 It is the installation structure diagram of the weighing assembly in the present invention.

[0034] Description of reference numerals:

[0035] In the figure: 1, diagonal support frame; 11, first roller; 2, frame; 21, I-shaped steel; 22, connecting frame; 23, second roller; 24, sprocket; 25, chain; 26, support sleeve; 27, clamping block; 28, limit seat; 3, hopper; 31, first bucket shell; 32, second bucket shell; 33, support block; 34, limit hole; 35, block; 36, assembly block; 41, U-shaped plate; 42, pressure sensor; 43, support foot; 44, square column; 45, hydraulic cylinder; 51, drive shaft; 52, gear; 53, rack; 54, worm gear box; 55, servo motor; 61, limit shaft; 62, limit wheel; 71, H-shaped frame; 72, support plate; 73, third roller; 74, connecting rod; 75, stopper; 76, arc block. DETAILED DESCRIPTION

[0036] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are clearly and completely described below in combination with the accompanying drawings and preferred embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present application, it should be understood that the orientation or position relationship indicated by "inside", "outside", etc. is based on the orientation or position described in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, a specific orientation structure and operation, and therefore cannot be understood as a limitation on the present application.

[0038] Reference Figure 1-Figure 9, is a telescopic hoist with a weighing structure disclosed in the present invention, comprising a diagonal support frame 1, a frame 2 and a hopper 3, the frame 2 is slidably mounted on the inclined surface of the diagonal support frame 1, the frame 2 comprises two I-shaped steels 21 and two connecting frames 22 which are fixedly connected end to end, a second roller 23 is mounted on the side away from the two I-shaped steels 21, the second roller 23 matches the inner side inclined rail of the diagonal support frame 1, and has a limiting function, first rollers 11 are fixedly mounted in the inner wall inclined rails on both sides facing each other of the diagonal support frame 1, the first roller 11 matches the adjacent I-shaped steels 21, and has a limiting function, the hopper 3 comprises a first bucket shell 31 and a second bucket shell 32, the first bucket shell 31 and the second bucket shell 32 are slidably connected in the vertical direction through four sets of limiting structures, the limiting The structure includes a support block 33, which is fixed to the side wall of the second bucket shell 32 by screws. Two limiting holes 34 are provided on the opposite sides of the first bucket shell 31. The support block 33 is slidably installed in the limiting holes 34 along the vertical direction. Two blocks 35 are provided on the bottom wall of the discharge port of the first bucket shell 31, and two assembly blocks 36 are provided on the bottom wall of the discharge port of the second bucket shell 32. The top of the block 35 is provided with an assembly groove, and the assembly block 36 matches the assembly groove of the block 35. The first roller 11 and the second roller 23 cooperate with the I-shaped steel 21 and the diagonal support frame 1, and have a rolling limiting function. When the frame 2 rises, the distance between the first roller 11 and the adjacent second roller 23 decreases. When the frame 2 descends, the distance between the first roller 11 and the adjacent second roller 23 increases.

[0039] A transmission assembly is arranged between the frame 2 and the hopper 3, and the transmission assembly includes a sprocket 24 and a chain 25. The two sprockets 24 are rotatably installed on the opposite sides of the two connecting frames 22 respectively, and the chain 25 is wound between the two sprockets 24. A clamping block 27 and a limiting seat 28 are fixedly installed on the side wall of the chain 25. The clamping block 27 is connected to the hopper 3 through a flip support assembly, and the limiting seat 28 is fixedly connected to the diagonal support frame 1. During the movement of the frame 2, since the limiting seat 28 is relatively fixed to the diagonal support frame 1, the two sprockets 24 are driven to rotate in cooperation with the chain 25, and the clamping block 27 slides relative to the frame 2, and the flip support assembly and the clamping block 27 slide synchronously.

[0040] A weighing assembly for weighing the weight of the material in the hopper 3 is provided on the diagonal support frame 1, and the weighing assembly includes a U-shaped plate 41, and the U-shaped plate 41 is located above the diagonal support frame 1. Four pressure sensors 42 are installed at the bottom end of the U-shaped plate 41, and the force-bearing screw of the pressure sensor 42 is connected to the support foot 43. Four square columns 44 are provided at the top of the U-shaped plate 41, and a hydraulic cylinder 45 is provided at the top of the square column 44. The piston rod of the hydraulic cylinder 45 matches the adjacent support block 33. During the process of feeding the material into the second bucket shell 32, the four hydraulic cylinders 45 of the controller respectively support the adjacent support blocks 33, and the support blocks 33 slide upward in the limit holes 34. The second bucket shell 32 slides synchronously in the first bucket shell 31. The four groups of pressure sensors 42 and the support feet 43 cooperate with the U-shaped plate 41 to weigh the material, which is convenient for quantitative transportation of the material.

[0041] A driving assembly for driving the frame 2 to slide is provided in the diagonal support frame 1, and the driving assembly includes a servo motor 55. A driving shaft 51 is penetrated and rotatably installed between the opposite sides of the diagonal support frame 1. The driving shaft 51 is key-connected with two gears 52. Racks 53 are provided at the bottom ends of the two I-shaped steels 21. The racks 53 are meshed with the gears 52. A worm gear transmission box 54 is provided on the outer wall of one side of the diagonal support frame 1. The servo motor 55 is fixedly installed on the outer wall of one side of the diagonal support frame 1. The output shaft of the servo motor 55 is fixedly connected to the input shaft of the worm gear transmission box 54 through a coupling. The servo motor 55 drives the worm gear transmission box 54 to transmit, drive the driving shaft 51 to rotate, the gear 52 and the rack 53 are meshed for transmission, and the I-shaped steel 21 and the connecting frame 22 rise or fall synchronously with the rack 53 in the diagonal support frame 1.

[0042] A flip support assembly is provided between the hopper 3 and the frame 2, and the flip support assembly includes an H-shaped frame 71, which is fixedly installed at the bottom end of the first bucket shell 31, and support plates 72 are rotatably installed on both sides of the H-shaped frame 71. The sides of the two support plates 72 that are away from each other are provided with third rollers 73, and the third rollers 73 match the inner side slide rails of the adjacent I-shaped steel 21. A connecting rod 74 is fixedly installed between the two support plates 72, and two arc blocks 76 are provided at the bottom end of the H-shaped frame 71. The arc blocks 76 match the support sleeve 26. A flip support assembly is provided between the flip support assembly and the frame 2. There is a stopping structure, which includes a support sleeve 26 and a stopper 75. The support plate 72 is composed of two square plates that are integrally arranged and flush with the top ends. The connecting frame 22 located above is rotatably installed with two support sleeves 26 through a rotating shaft. The stopper 75 is fixedly installed at the bottom end of the H-shaped frame 71. The stopper 75 matches the support sleeve 26. The flip support assembly slides synchronously with the clamping block 27. The two third rollers 73 roll in the slide rails of the two I-shaped steels 21. When the stopper 75 is against the support sleeve 26, the H-shaped frame 71 and the hopper 3 are flipped over to pour out the material, and the hopper 3 is driven to reset through the driving assembly and the transmission assembly.

[0043] A limiting assembly for auxiliary supporting the frame 2 is provided at the top of the diagonal support frame 1, and the limiting assembly includes a limiting shaft 61, which passes through and is rotatably installed on the opposite sides of the top of the diagonal support frame 1. The limiting shaft 61 is sleeved with two limiting wheels 62, and the limiting wheels 62 are matched with the I-shaped steel 21. During the rising or falling process of the frame 2, the two limiting wheels 62 respectively assist in supporting the two I-shaped steels 21 to improve the stability of the elevator.

[0044] The working principle and use process of the present invention are as follows: during the process of feeding materials into the second bucket shell 32, the four hydraulic cylinders 45 of the controller respectively prop up the adjacent support blocks 33, the support blocks 33 slide upward in the limit holes 34, the second bucket shell 32 slides synchronously in the first bucket shell 31, the four groups of pressure sensors 42 and the support feet 43 cooperate with the U-shaped plate 41 to weigh the materials, which is convenient for quantitative transportation of the materials, the servo motor 55 drives the worm gear transmission box 54 to drive the drive shaft 51 to rotate, the gear 52 and the rack 53 mesh and transmit, the I-shaped steel 21 and the connecting frame 22 and the rack 53 rise or fall synchronously in the diagonal support frame 1, the first roller 11 and the second roller 23 cooperate with the I-shaped steel 21 and the diagonal support frame 1, and have a rolling limit Function: when the frame 2 rises, the distance between the first roller 11 and the adjacent second roller 23 decreases; when the frame 2 descends, the distance between the first roller 11 and the adjacent second roller 23 increases; the two limiting wheels 62 respectively assist in supporting the two I-shaped steels 21 to improve the stability of the elevator; during the movement of the frame 2, since the limiting seat 28 is relatively fixed to the diagonal support frame 1, the chain 25 is cooperated to drive the two sprockets 24 to rotate, and the clamping block 27 slides relative to the frame 2, and the flip support assembly slides synchronously with the clamping block 27, and the two third rollers 73 roll in the slide rails of the two I-shaped steels 21. When the block 75 resists the support sleeve 26, the H-shaped frame 71 and the hopper 3 are flipped over to pour out the material, and the hopper 3 is reset through the driving assembly and the transmission assembly.

[0045] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A telescopic hoist with a weighing structure, comprising a diagonal support frame (1), a frame (2) and a hopper (3), characterized in that: The frame (2) is slidably mounted on the inclined surface of the inclined support frame (1); a transmission assembly is arranged between the frame (2) and the hopper (3); a weighing assembly for weighing the weight of the material in the hopper (3) is arranged on the inclined support frame (1); a driving assembly for driving the frame (2) to slide is arranged in the inclined support frame (1); a flip support assembly is arranged between the hopper (3) and the frame (2); and a limit assembly for assisting the support frame (2) is arranged at the top end of the inclined support frame (1); The frame (2) comprises two I-shaped steels (21) and two connecting frames (22) which are fixedly connected end to end. A second roller (23) is installed on the side away from each other of the two I-shaped steels (21), and the second roller (23) matches the inner side inclined rail of the diagonal support frame (1). First rollers (11) are fixedly installed in the inner wall inclined rails on the opposite sides of the diagonal support frame (1), and the first rollers (11) match the adjacent I-shaped steels (21); The transmission assembly comprises a sprocket (24) and a chain (25), wherein the two sprockets (24) are rotatably mounted on opposite sides of two connecting frames (22), and the chain (25) is wound between the two sprockets (24). A clamping block (27) and a limiting seat (28) are fixedly mounted on the side wall of the chain (25), wherein the clamping block (27) is connected to the hopper (3) via a flip support assembly, and the limiting seat (28) is fixedly connected to the diagonal support frame (1); The hopper (3) comprises a first hopper shell (31) and a second hopper shell (32), wherein the first hopper shell (31) and the second hopper shell (32) are slidably connected in a vertical direction via four sets of limiting structures, and a weighing assembly is connected to the bottom of the limiting structure; The limiting structure comprises a support block (33), the support block (33) being fixedly mounted on the side wall of the second bucket shell (32) by means of screws, two limiting holes (34) being arranged on opposite sides of the first bucket shell (31), the support block (33) being slidably mounted in the limiting holes (34) along a vertical direction; The weighing assembly comprises a U-shaped plate (41), wherein the U-shaped plate (41) is located above the diagonal support frame (1), four pressure sensors (42) are installed at the bottom end of the U-shaped plate (41), the force-bearing screws of the pressure sensors (42) are connected to support feet (43), four square columns (44) are arranged at the top end of the U-shaped plate (41), a hydraulic cylinder (45) is arranged at the top end of the square column (44), and the piston rod of the hydraulic cylinder (45) matches the adjacent support block (33); The flip support assembly comprises an H-shaped frame (71), the H-shaped frame (71) being fixedly mounted on the bottom end of the first bucket shell (31), support plates (72) being rotatably mounted on opposite sides of the H-shaped frame (71), third rollers (73) being arranged on the sides of the two support plates (72) that are away from each other, the third rollers (73) being matched with inner side slide rails of adjacent I-shaped steel members (21), a connecting rod (74) being fixedly mounted between the two support plates (72), two arc blocks (76) being arranged at the bottom end of the H-shaped frame (71), the arc blocks (76) being matched with the support sleeves (26), and a stop structure being arranged between the flip support assembly and the frame (2).

2. A telescopic hoist with a weighing structure according to claim 1, characterized in that: The bottom wall of the discharge port of the first bucket shell (31) is provided with two blocks (35), and the bottom wall of the discharge port of the second bucket shell (32) is provided with two assembly blocks (36). The tops of the blocks (35) are provided with assembly grooves, and the assembly blocks (36) match the assembly grooves of the blocks (35).

3. The telescopic hoist with a weighing structure according to claim 1, characterized in that: The driving assembly comprises a servo motor (55), a driving shaft (51) passing through and rotatably installed between two opposing sides of the diagonal support frame (1), the driving shaft (51) being key-connected to two gears (52), a rack (53) being arranged at the bottom ends of the two I-shaped steel materials (21), the rack (53) being arranged in meshing engagement with the gear (52), a worm gear transmission box (54) being arranged on an outer wall of one side of the diagonal support frame (1), the servo motor (55) being fixedly installed on an outer wall of one side of the diagonal support frame (1), and an output shaft of the servo motor (55) being fixedly connected to an input shaft of the worm gear transmission box (54) via a coupling.

4. The telescopic hoist with a weighing structure according to claim 1, characterized in that: The limiting assembly comprises a limiting shaft (61), the limiting shaft (61) passes through and is rotatably mounted on two opposite sides of the top of the diagonal support frame (1), the limiting shaft (61) is sleeved with two limiting wheels (62), and the limiting wheels (62) match the I-shaped steel (21).

5. The telescopic hoist with a weighing structure according to claim 1, characterized in that: The blocking structure comprises a support sleeve (26) and a stopper (75); the support plate (72) is composed of two square plates which are integrally arranged and have flush top ends; the connecting frame (22) located above is rotatably mounted with two support sleeves (26) via a rotating shaft; the stopper (75) is fixedly mounted on the bottom end of the H-shaped frame (71); the stopper (75) matches the support sleeve (26).

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