CN111220539A

CN111220539A - Anti-stripping test device for asphalt mixture

Info

Publication number: CN111220539A
Application number: CN202010039417.4A
Authority: CN
Inventors: 王亚西
Original assignee: Gansu Leda Culture Communication Co Ltd
Current assignee: Gansu Leda Culture Communication Co Ltd
Priority date: 2020-01-15
Filing date: 2020-01-15
Publication date: 2020-06-02

Abstract

The invention discloses an asphalt mixture anti-stripping test device which comprises a sample cabin to be tested, wherein the sample cabin to be tested is arranged in a placing mechanism, a material collecting cavity is fixedly arranged on the outer side of the sample cabin to be tested, a moving mechanism is arranged on the outer side of the material collecting cavity, a leveling plate is arranged in the moving mechanism, an adjusting mechanism is arranged on the moving mechanism, a bevel gear is arranged in the adjusting mechanism, and a pressing mechanism is arranged on the moving mechanism. According to the invention, the packing paper is laid in the sample bin to be tested, so that the adhesion degree of the asphalt mixture and the inner wall of the sample bin to be tested is effectively reduced, meanwhile, the bottom of the sample bin to be tested is arranged in a penetrating manner, and the bottom plate is arranged to be in sliding connection with the sample bin to be tested through the clamping groove, so that after the test is finished, the bottom plate can be pulled out, and the asphalt mixture falls out of the sample bin to be tested by pressing downwards, so that the convenience degree of taking out the asphalt mixture is greatly improved.

Description

Anti-stripping test device for asphalt mixture

Technical Field

The invention relates to the technical field of asphalt mixture test equipment, in particular to an asphalt mixture anti-stripping test device.

Background

The asphalt mixture is also called as asphalt concrete, is a mixture prepared by mixing manually selected mineral aggregate with a certain gradation composition with materials such as broken stone or crushed gravel, stone chips or sand, mineral powder and the like and road asphalt material in a certain proportion, is usually used for pavement construction, and in the actual pavement construction process of the asphalt mixture, a sample of the asphalt mixture needs to be subjected to an anti-stripping test firstly to ensure that the asphalt mixture can reach the building standard.

The method is characterized in that a pressurizing and rubbing mode is generally adopted when the asphalt mixture is subjected to a stripping resistance test, then scraps fallen by rubbing are weighed and used for comparing and measuring the stripping resistance degree of the asphalt mixture, and the asphalt mixture is located in test equipment during the test process because the asphalt mixture has strong viscosity and has high strength after being shaped, and is inconvenient to clean and take out after the test is finished;

in addition, when the test preparation is carried out, the asphalt material is flatly laid in the equipment, the surface of the asphalt material is not flat enough, and the accuracy of the anti-stripping test is easily influenced.

Disclosure of Invention

The invention aims to provide an asphalt mixture anti-stripping test device, which is used for solving the problems that equipment used in the existing asphalt mixture anti-stripping test in the background art is convenient for leveling the upper surface of an asphalt material, the accuracy of a measurement result is influenced, and the asphalt mixture is inconvenient to take out after the test is finished.

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides an anti test device that peels off of bituminous mixture, includes the sample storehouse that awaits measuring, the internally mounted of placement mechanism has the sample storehouse that awaits measuring, and the outside fixed mounting in sample storehouse that awaits measuring has a collecting chamber, moving mechanism is installed in the outside in collecting chamber, and moving mechanism's internally mounted has the flattening board, the last adjustment mechanism that installs of moving mechanism, and adjustment mechanism's internally mounted has a bevel gear, the last hold-down mechanism that installs of moving mechanism.

Preferably, the placing mechanism comprises a sample cabin to be tested, packing paper, a clamping groove and a bottom plate, the packing paper is laid in the sample cabin to be tested, the clamping groove is symmetrically formed in the side wall of the bottom of the sample cabin to be tested, the bottom plate is inserted in the clamping groove, the upper side and the lower side of the sample cabin to be tested are in a penetrating mode, and the bottom plate is connected with the sample cabin to be tested in a sliding mode through the clamping groove.

Preferably, moving mechanism includes guide rail, movable block, first screw rod, crossbeam, support column, fixed plate, pivot, flattening board and push pedal, the guide rail is provided with two sets ofly altogether, and is two sets of the guide rail is the symmetry form and fixes both sides around the chamber of gathering materials, and is two sets of the inside of guide rail is inlayed respectively and is had the movable block, and one of them is a set of the inside of movable block is inserted and is equipped with first screw rod, and is two sets of welded fastening has the crossbeam between the upper end of movable block, and the top symmetry of crossbeam is fixed with two sets of support columns, and is two sets of welded fastening has the fixed plate between the support column, and is two sets of insert between the support column and be equipped with the pivot, and the outside fixed mounting of pivot has the flattening.

Preferably, the crossbeam passes through movable block and guide rail sliding connection, first screw rod is inserted and is established the inside of guide rail, first screw rod rotates with the guide rail and is connected, evenly be equipped with the screw thread on the inner wall of movable block, evenly be equipped with the screw thread on the outer wall of first screw rod, and the screw thread looks adaptation of assembling on the screw thread of just assembling on the first screw rod outer wall and the movable block inner wall, first screw rod passes through the meshing of screw thread and movable block screw thread swivelling joint.

Preferably, the adjusting mechanism comprises a first transmission rod, a second transmission rod, an adjusting block, a limiting sleeve and a bevel gear, the first transmission rod is inserted into a group of support columns, the second transmission rod is inserted above the first transmission rod, the adjusting block is fixedly installed at the top of the second transmission rod, the limiting sleeve is fixedly welded above the support columns, the bevel gear is fixedly installed at the bottom of the first transmission rod, limiting grooves are symmetrically formed in the inner wall of the first transmission rod, limiting blocks are symmetrically welded on the outer wall of the second transmission rod, the second transmission rod is in sliding telescopic connection with the first transmission rod through the matching of the limiting grooves and the limiting blocks, the limiting blocks are uniformly fixed on the outer side of the adjusting block, limiting grooves are uniformly formed in the inner wall of the limiting sleeve, and the limiting grooves formed in the inner wall of the limiting sleeve are matched with the limiting blocks fixed on the outer wall of the adjusting block, the bevel gears are arranged in two groups, the two groups of bevel gears are respectively fixed at one end of the first transmission rod and one end of the rotating shaft, and the two groups of bevel gears are connected in a meshed mode.

Preferably, the pressing mechanism comprises a clamping frame, a threaded sleeve, a second screw rod, a limiting plate and a friction pressing plate, the clamping frame is provided with two groups, two groups of the clamping frames are respectively fixed on one side of the fixed plate in a symmetrical manner, a threaded sleeve is fixedly arranged between the two groups of the clamping frames, a second screw rod is inserted in the screw sleeve, the bottom of the second screw rod is hinged with a limiting plate, the bottom of the limiting plate is fixedly provided with a friction pressing plate, the threads assembled on the outer wall of the second screw are matched with the threads assembled on the inner wall of the screw sleeve, the second screw is rotationally connected with the screw sleeve threads through the meshing of the threads, sliding grooves are symmetrically formed on the side walls of the two groups of clamping frames, the limiting plates are inserted into sliding grooves formed in the two groups of clamping frames, the limiting plates are connected with the clamping frames in a sliding mode through the sliding grooves, and the limiting plates are connected with the second screw in a rotating mode.

Compared with the prior art, the invention has the beneficial effects that:

1. through having laid the packing paper in the inside in the sample storehouse that awaits measuring, the effectual reduction bituminous mixture glues the degree with gluing of the sample storehouse inner wall that awaits measuring, simultaneously, the bottom that sets up the sample storehouse that awaits measuring is for running through the form, and sets up the bottom plate and passes through draw-in groove sliding connection with the sample storehouse that awaits measuring for the device can take out the bottom plate through the pull after the experiment, and press down and make bituminous mixture drop out from the sample storehouse that awaits measuring, has improved the convenient degree that bituminous mixture took out greatly.

2. Through setting up first screw rod and movable block screw thread swivelling joint in the moving mechanism for when rotating first screw rod, can remove through screw thread drive movable block, thereby drive the flattening board and remove, carry out the flattening operation to bituminous mixture upper surface through the flattening board, the upper surface unevenness after the effectual bituminous mixture that prevents solidifies causes the influence to the measuring result, and simultaneously, unnecessary bituminous mixture is pushed the intracavity portion that gathers materials by the flattening board and is collected, effectual reduction is to bituminous mixture's waste.

Drawings

FIG. 1 is a schematic top view of the structure of the present invention;

FIG. 2 is a schematic side cross-sectional view of the structure of FIG. 1 at A-A according to the present invention;

FIG. 3 is a schematic side cross-sectional view of the structure of FIG. 1 at B-B according to the present invention;

FIG. 4 is an enlarged view of the structure of FIG. 3 at C according to the present invention;

FIG. 5 is a side view of the connection between the shaft and the screed plate structure of the present invention.

In the figure: 11. a sample bin to be tested; 12. packing paper; 13. a card slot; 14. a base plate; 2. a material collecting cavity; 31. a guide rail; 32. a movable block; 33. a first screw; 34. a cross beam; 35. a support pillar; 36. a fixing plate; 37. a rotating shaft; 38. a screed plate; 39. pushing the plate; 41. a first drive lever; 42. a second transmission rod; 43. an adjusting block; 44. a limiting sleeve; 45. a bevel gear; 51. a clamping frame; 52. a threaded sleeve; 53. a second screw; 54. a limiting plate; 55. and rubbing the pressure plate.

Detailed Description

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

Referring to fig. 1-5, an embodiment of the present invention is shown:

an asphalt mixture anti-stripping test device comprises a sample cabin 11 to be tested, the sample cabin 11 to be tested is arranged in a placing mechanism, the placing mechanism comprises the sample cabin 11 to be tested, packing paper 12, a clamping groove 13 and a bottom plate 14, the packing paper 12 is laid in the sample cabin 11 to be tested, the clamping groove 13 is symmetrically arranged on the side wall of the bottom of the sample cabin 11 to be tested, the bottom plate 14 is inserted in the clamping groove 13, the upper side and the lower side of the sample cabin 11 to be tested are in a penetrating shape, the bottom plate 14 is in sliding connection with the sample cabin 11 to be tested through the clamping groove 13, when in use, if asphalt mixture needs to be added into the device, the packing paper 12 is arranged to isolate the sample cabin 11 to be tested from the asphalt mixture, the probability that the asphalt mixture is adhered to the sample cabin 11 to be tested is effectively reduced, meanwhile, the bottom plate 14 is arranged to be inserted in the clamping groove 13 arranged at the bottom of the sample cabin, after the test is completed, the asphalt mixture can be taken out from the bottom of the bottom plate 14 only by pressing downwards, and the device is convenient to use and convenient to operate.

The outer side of a sample cabin 11 to be tested is fixedly provided with a material collecting cavity 2, the bottom of the material collecting cavity 2 is arc-shaped, when the device is used, the material collecting cavity 2 can collect redundant raw materials of asphalt mixture, the waste of the asphalt mixture is effectively prevented, and meanwhile, the crushed aggregates of the asphalt mixture falling in a stripping test can be resisted and collected, so that the device is more accurate and convenient when samples are collected, the outer side of the material collecting cavity 2 is provided with a moving mechanism, the inside of the moving mechanism is provided with a leveling plate 38, the moving mechanism comprises guide rails 31, movable blocks 32, a first screw 33, a cross beam 34, a support column 35, a fixed plate 36, a rotating shaft 37, the leveling plate 38 and a push plate 39, the guide rails 31 are provided with two groups, the two groups of guide rails 31 are symmetrically fixed on the front side and the back side of the material collecting cavity 2, the movable blocks 32 are respectively embedded in the two groups of guide, a cross beam 34 is welded and fixed between the upper ends of the two groups of movable blocks 32, two groups of supporting columns 35 are symmetrically fixed on the top of the cross beam 34, a fixing plate 36 is welded and fixed between the two groups of supporting columns 35, a rotating shaft 37 is inserted between the two groups of supporting columns 35, a leveling plate 38 is fixedly installed on the outer side of the rotating shaft 37, two groups of push plates 39 are symmetrically and fixedly welded below the cross beam 34, the cross beam 34 is slidably connected with the guide rail 31 through the movable blocks 32, a first screw 33 is inserted in the guide rail 31, the first screw 33 is rotatably connected with the guide rail 31, threads are uniformly assembled on the inner wall of the movable blocks 32, threads are uniformly assembled on the outer wall of the first screw 33, the threads assembled on the outer wall of the first screw 33 are matched with the threads assembled on the inner wall of the movable blocks 32, the first screw 33 is rotatably connected with the threads of the movable blocks 32 through meshing, under the meshing action of the threads, the movable block 32 can be driven to move inside the guide rail 31, the cross beam 34 fixed above the movable block 32 can be driven to move through the movable block 32, so that the leveling plate 38 is driven to move, the bottom of the leveling plate 38 is inclined towards two sides, redundant parts above the asphalt mixture can be effectively scraped into the material collecting cavity 2 to be collected in the moving process, meanwhile, the brushes are uniformly arranged above the leveling plate 38, when the anti-stripping test is carried out, a worker can make the brushes contact the surface of the asphalt mixture by adjusting the position of the leveling plate 38, then the brushes sweep the fallen asphalt mixture into the material collecting cavity 2 to be collected through the movement of the leveling plate 38, the fallen samples are convenient to be collected, meanwhile, the bottom of the push plate 39 is arc-shaped and is attached to the inside of the material collecting cavity 2, the cross beam 34 drives the push plate 39 to move when moving, so that the asphalt mixture in the aggregate cavity 2 can be pushed to form a pile, and the asphalt mixture can be collected conveniently.

The moving mechanism is provided with an adjusting mechanism, a bevel gear 45 is arranged inside the adjusting mechanism, the adjusting mechanism comprises a first transmission rod 41, a second transmission rod 42, an adjusting block 43, a limiting sleeve 44 and a bevel gear 45, the first transmission rod 41 is inserted inside a group of support pillars 35, the second transmission rod 42 is inserted above the first transmission rod 41, the adjusting block 43 is fixedly arranged at the top of the second transmission rod 42, the limiting sleeve 44 is fixedly welded above the support pillars 35, the bevel gear 45 is fixedly arranged at the bottom of the first transmission rod 41, limiting grooves are symmetrically formed in the inner wall of the first transmission rod 41, limiting blocks are symmetrically welded on the outer wall of the second transmission rod 42, the second transmission rod 42 is in sliding telescopic connection with the first transmission rod 41 through the matching of the limiting grooves and the limiting blocks, the limiting blocks are uniformly fixed on the outer side of the adjusting block 43, the limiting grooves are uniformly formed in the inner wall of the, and the spacing groove that sets up on the inner wall of stop collar 44 and the fixed stopper looks adaptation on the regulating block 43 outer wall, bevel gear 45 is provided with two sets ofly altogether, and two sets of bevel gear 45 fix the one end at first transfer line 41 and the one end of pivot 37 respectively, two sets of bevel gear 45 mesh is connected, in operation, if the operating condition of change flattening board 38, can be through upwards pulling regulating block 43, make regulating block 43 break away from the restriction of spacing sleeve 44 fixed, the staff is through rotating regulating block 43, under the transmission of second transfer line 42 and first transfer line 41, make bevel gear 45 rotate, through the meshing transmission of two sets of bevel gear 45, make pivot 37 drive flattening board 38 rotate, change the position with the upper and lower both sides of flattening board 38, effectual adjustment according to the in service behavior is to the state of whole flattening board 38, high durability and convenient use.

The moving mechanism is provided with a pressing mechanism, the pressing mechanism comprises two groups of clamping frames 51, a threaded sleeve 52, a second screw 53, a limiting plate 54 and a friction pressing plate 55, the two groups of clamping frames 51 are respectively fixed on one side of the fixed plate 36 in a symmetrical manner, the threaded sleeve 52 is fixedly arranged between the two groups of clamping frames 51, the second screw 53 is inserted in the threaded sleeve 52, the bottom of the second screw 53 is hinged with the limiting plate 54, the friction pressing plate 55 is fixedly arranged at the bottom of the limiting plate 54, threads assembled on the outer wall of the second screw 53 are matched with threads assembled on the inner wall of the threaded sleeve 52, the second screw 53 is rotatably connected with the threaded sleeve 52 through meshing of the threads, sliding grooves are symmetrically formed in the side walls of the two groups of clamping frames 51, the limiting plate 54 is inserted in the sliding grooves formed in the two groups of clamping frames 51, and the limiting plate 54 is slidably connected with the clamping frames 51 through the sliding grooves, the limiting plate 54 is rotatably connected with the second screw 53, when the anti-stripping test is performed, a worker can rotate the second screw 53, the second screw 53 is meshed with the thread of the thread sleeve 52, the second screw 53 moves downwards in the thread sleeve 52, meanwhile, the second screw 53 pushes the limiting plate 54 downwards, the friction pressing plate 55 is attached and pressed on the surface of the asphalt mixture, the asphalt mixture is extruded, then, the worker drives the moving mechanism to move by rotating the first screw 33, the friction pressing plate 55 moves on the surface of the asphalt mixture to perform friction scraping and brushing, and the friction pressing plate 55 can move by rotating the first screw 33 under the condition that the friction force with the surface of the asphalt is too large to move, so that the anti-stripping test is performed on the asphalt mixture by the device.

The working principle is as follows: during work, if an anti-stripping test of the asphalt mixture is required, a worker lays the packing paper 12 in the sample bin 11 to be tested, then the asphalt mixture is laid on the surface of the packing paper 12, after the asphalt mixture is laid, the worker rotates the first screw 33, the movable block 32 moves in the guide rail 31 under the meshing of the threads, the cross beam 34 is driven to move, the leveling plate 38 is enabled to be leveled on the surface of the asphalt mixture, the redundant part of the asphalt mixture is pushed out to two sides, and the redundant mixture falls into the material collecting cavity 2 and is collected;

after the asphalt mixture is solidified, the worker pulls the adjusting block 43 upwards to make the adjusting block 43 move upwards and separate from the inside of the limiting sleeve 44, then the worker rotates the adjusting block 43, the bevel gears 45 rotate through the transmission of the second transmission rod 42 and the first transmission rod 41, the rotating shaft 37 drives the leveling plate 38 to rotate through the meshing of the two groups of bevel gears 45, the brush above the leveling plate 38 rotates, the worker presses the adjusting block 43 downwards to make the adjusting block 43 clamped inside the limiting sleeve 44 again for fixing, the worker rotates the second screw 53 according to the requirement of the anti-stripping test, under the meshing of the threads, the second screw 53 moves downwards inside the screw sleeve 52 to drive the limiting plate 54 to move downwards, so that the friction pressure plate 55 is extruded and attached to the surface of the asphalt mixture, the worker rotates the first screw 33 to drive the moving mechanism to move, the friction pressing plate 55 is made to move on the surface of the asphalt mixture to scrape the brush, the abraded asphalt mixture falling off is cleaned by the brush on the leveling plate 38 to the inside of the aggregate cavity 2 to be collected, and the anti-stripping performance of the asphalt mixture is measured through measuring falling debris and weighing comparison.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims

1. The utility model provides an anti peeling test device of bituminous mixture, includes sample storehouse (11) that awaits measuring, its characterized in that: the utility model discloses a sample storage device, including placing mechanism, sample storehouse (11) that awaits measuring, the outside fixed mounting in sample storehouse (11) that just awaits measuring has a collecting cavity (2), moving mechanism is installed in the outside in collecting cavity (2), and moving mechanism's internally mounted has flattening board (38), install adjustment mechanism on the moving mechanism, and adjustment mechanism's internally mounted has bevel gear (45), the last hold-down mechanism that installs of moving mechanism.

2. The asphalt mixture anti-stripping test device according to claim 1, characterized in that: place the mechanism including sample storehouse (11), packing paper (12), draw-in groove (13) and bottom plate (14) that await measuring, packing paper (12) have been laid to the inside in sample storehouse (11) that awaits measuring, draw-in groove (13) have been seted up to the symmetry on the bottom lateral wall in sample storehouse (11) that awaits measuring, and the inside of draw-in groove (13) is inserted and is equipped with bottom plate (14), the upper and lower both sides in sample storehouse (11) that await measuring are for running through the form, bottom plate (14) are through draw-in groove (13) and sample storehouse (11) sliding connection that awaits.

3. The asphalt mixture anti-stripping test device according to claim 1, characterized in that: the moving mechanism comprises guide rails (31), movable blocks (32), first screw rods (33), cross beams (34), support columns (35), fixed plates (36), rotating shafts (37), leveling plates (38) and push plates (39), wherein the guide rails (31) are provided with two groups, the guide rails (31) are symmetrically fixed on the front side and the rear side of the material collecting cavity (2), the movable blocks (32) are respectively embedded in the guide rails (31), the first screw rods (33) are inserted in the movable blocks (32), the cross beams (34) are welded and fixed between the upper ends of the movable blocks (32), the two groups of support columns (35) are symmetrically fixed on the top of the cross beams (34), the fixed plates (36) are welded and fixed between the two groups of support columns (35), and the rotating shafts (37) are inserted between the two groups of support columns (35), and the outside fixed mounting of pivot (37) has flattening board (38), the below symmetry fixed welding of crossbeam (34) has two sets of push pedals (39).

4. The asphalt mixture anti-stripping test device according to claim 3, characterized in that: crossbeam (34) are through movable block (32) and guide rail (31) sliding connection, first screw rod (33) are inserted and are established the inside in guide rail (31), first screw rod (33) are rotated with guide rail (31) and are connected, evenly be equipped with the screw thread on the inner wall of movable block (32), evenly be equipped with the screw thread on the outer wall of first screw rod (33), and the screw thread looks adaptation of assembly on the screw thread of assembly and movable block (32) inner wall on first screw rod (33) outer wall, first screw rod (33) are through threaded meshing and movable block (32) screw thread swivelling joint.

5. The asphalt mixture anti-stripping test device according to claim 3, characterized in that: the adjusting mechanism comprises a first transmission rod (41), a second transmission rod (42), an adjusting block (43), a limiting sleeve (44) and a bevel gear (45), the first transmission rod (41) is inserted into the supporting column (35), the second transmission rod (42) is inserted above the first transmission rod (41), the adjusting block (43) is fixedly installed at the top of the second transmission rod (42), the limiting sleeve (44) is fixedly welded above the supporting column (35), the bevel gear (45) is fixedly installed at the bottom of the first transmission rod (41), limiting grooves are symmetrically formed in the inner wall of the first transmission rod (41), limiting blocks are symmetrically welded on the outer wall of the second transmission rod (42), the second transmission rod (42) is in sliding telescopic connection with the first transmission rod (41) through matching of the limiting grooves and the limiting blocks, and the limiting blocks are uniformly fixed on the outer side of the adjusting block (43), the inner wall of the limiting sleeve (44) is evenly provided with limiting grooves, the limiting grooves formed in the inner wall of the limiting sleeve (44) are matched with limiting blocks fixed on the outer wall of the adjusting block (43), the bevel gears (45) are arranged in two groups, the bevel gears (45) are fixed to one end of the first transmission rod (41) and one end of the rotating shaft (37) respectively, and the bevel gears (45) are meshed and connected in two groups.

6. The asphalt mixture anti-stripping test device according to claim 3, characterized in that: the pressing mechanism comprises clamping frames (51), threaded sleeves (52), second screw rods (53), limiting plates (54) and friction pressing plates (55), wherein the clamping frames (51) are provided with two groups, the two groups of clamping frames (51) are symmetrically fixed on one side of the fixing plate (36) respectively, the threaded sleeves (52) are fixedly arranged between the two groups of clamping frames (51), the second screw rods (53) are inserted in the threaded sleeves (52), the limiting plates (54) are hinged to the bottoms of the second screw rods (53), the friction pressing plates (55) are fixedly arranged at the bottoms of the limiting plates (54), threads assembled on the outer walls of the second screw rods (53) are matched with threads assembled on the inner walls of the threaded sleeves (52), the second screw rods (53) are rotatably connected with the threaded sleeves (52) through meshing of the threads, sliding grooves are symmetrically formed in the side walls of the two groups of clamping frames (51), the limiting plates (54) are inserted into sliding grooves formed in the two groups of clamping frames (51), the limiting plates (54) are connected with the clamping frames (51) in a sliding mode through the sliding grooves, and the limiting plates (54) are connected with the second screw rods (53) in a rotating mode.