CN219224797U - 3D prints cement-based material printability testing arrangement - Google Patents

Abstract

The application relates to a 3D prints cement-based material printability testing arrangement, belongs to cement-based technical field, and it includes workstation, stand, slide, link, barrel, extrusion nozzle and pressure piece, and the stand slides and sets up on the workstation, has seted up the spout along vertical direction on the stand, and the slide slides and sets up in the spout; the connecting frame is arranged on the sliding seat, and the cylinder body is detachably arranged on the connecting frame; the extrusion nozzle is detachably arranged at the bottom of the cylinder body, and the pressure piece is detachably arranged in the cylinder body; be provided with horizontal drive assembly on the workstation, be provided with vertical drive assembly on the stand. The transverse driving assembly drives the upright post to horizontally slide on the workbench, the vertical driving assembly drives the sliding seat to slide in the sliding groove, so that the movement of the cement-based material in the cylinder in the 3D printing process can be simulated, and the problems of errors of detection data and actual use during the cement-based material test are effectively solved.

Description

3D prints cement-based material printability testing arrangement

Technical Field

The application relates to the field of cement-based technologies, in particular to a 3D printing cement-based material printability testing device.

Background

Along with the development of 3D printing technology in the building industry, the application of wallboard, ceiling, windowsill and other building components prefabricated by 3D printing technology in building engineering is gradually increased, but the cement-based composite material is a composite material formed by taking Portland cement as a matrix, various fibers and metal wires as reinforcements, and adding filler, chemical auxiliary agent and water through a composite process, and is commonly used in the 3D printing manufacture of building components due to the better performance than that of common concrete; however, before 3D printing is performed by using the cement-based composite material, performance tests such as extrusion continuity and volume stability of the cement-based composite material are generally required, so that each performance of the cement-based composite material is ensured to be matched with the performance of the material required by 3D printing, and further the quality of the 3D printed building member is ensured.

At present, the conventional test methods for the performances such as extrusion continuity, volume stability and the like of cement-based composite materials are generally as follows: pouring the viscous cement-based composite material into a test cylinder, adding a pressure piece into the test cylinder, extruding the cement-based material in the test cylinder, and observing and measuring the performances such as the continuity, the volume stability and the like of the extruded cement-based material at the bottom of the test cylinder.

With respect to the above-described related art, the inventors found that there are the following drawbacks: because the printing process of the 3D printing building component is a dynamic process of continuous motion, the existing performance detection of the cement-based composite material is usually static detection, and errors exist between detection data and actual use.

Disclosure of Invention

In order to solve the problem that errors exist between detection data when testing cement-based materials and actual use, the application provides a 3D printing cement-based material printability testing device.

The application provides a 3D prints cement-based material printability testing arrangement adopts following technical scheme:

the 3D printing cement-based material printability testing device comprises a workbench, an upright post, a sliding seat, a connecting frame, a cylinder body, an extrusion nozzle and a pressure piece, wherein the upright post is arranged on the workbench in a sliding manner, a sliding groove is formed in the upright post in the vertical direction, and the sliding seat is arranged in the sliding groove in a sliding manner; the connecting frame is arranged on the sliding seat, the inside of the cylinder body is hollow, the two ends of the cylinder body are provided with openings, and the cylinder body is detachably arranged on the connecting frame; the extrusion nozzle is detachably arranged at the bottom of the cylinder, and the pressure piece is detachably arranged in the cylinder and is used for applying pressure to cement-based materials in the cylinder; the workbench is provided with a transverse driving assembly for driving the upright post to horizontally slide on the workbench; the upright post is provided with a vertical driving component for driving the sliding seat to slide in the sliding groove.

Through adopting above-mentioned technical scheme, the tester packs into the barrel with the cement-based material that prepares, put into the barrel with the pressure spare again and exert pressure to the cement-based material in the barrel, horizontal drive assembly orders about the stand simultaneously and slides on the workstation level, vertical drive assembly orders about the slide in the spout and slides, can simulate the removal of cement-based material in the barrel in the 3D printing process, through observing the cement-based material that extrudes from the extrusion nozzle, can obtain the detection data of cement-based material in the dynamic in-process of 3D printing, effectively improve the problem that has the error when testing the detection data and the in-service use to cement-based material.

Optionally, the transverse driving assembly comprises a cylinder, the cylinder is arranged on the workbench, and a piston rod of the cylinder is connected with the upright post.

Through adopting above-mentioned technical scheme, through the piston rod extension or the retract of control cylinder, can control the stand and reciprocate the slip on the workstation, the testers order about the stand and reciprocate the slip convenience on the workstation.

Optionally, the telescopic direction along the piston rod of cylinder is provided with the guide rail on the workstation, the stand slides and the joint is in the guide rail.

Through adopting above-mentioned technical scheme, the guide rail is inside with the stand centre gripping for the stand can only follow the guide rail and slide at length direction, effectively improves the gliding stability of guide rail on the workstation.

Optionally, the vertical driving assembly comprises a screw and a first motor, the screw is rotatably arranged on the top wall of the chute, and the screw thread is arranged on the sliding seat in a penetrating way; the first motor is arranged on the upright post, and an output shaft of the first motor is coaxially connected with the screw rod.

Through adopting above-mentioned technical scheme, the output shaft of first motor drives the lead screw and rotates, and then makes the slide in the spout along the length direction of spout, realizes the reciprocal slip of slide in the spout through the positive and negative rotation of the output shaft of control first motor, and the tester orders about the slide convenient in the spout.

Optionally, one end of the cylinder body, which is close to the workbench, is provided with a threaded joint, and the extrusion nozzle is arranged on the threaded joint in a threaded manner.

Through adopting above-mentioned technical scheme, the extrusion nozzle screw thread is installed on screwed joint, and the installation of the extrusion nozzle of being convenient for is torn open, and the extrusion nozzle of the different opening sizes of the tester of being convenient for change.

Optionally, the cylinder is provided with a receiving ring, and the diameter of the receiving ring is larger than that of the cylinder.

By adopting the technical scheme, the cement-based materials overflowed from the cylinder body flow to the receiving ring along the outer wall of the cylinder body for collection, so that the cement-based materials overflowed from the cylinder body can be collected by the tester conveniently.

Optionally, the link includes bracing piece and snap ring, the bracing piece sets up on the slide, the snap ring sets up on the bracing piece, just the internal diameter of snap ring and the external diameter adaptation of barrel, but the internal diameter of snap ring is less than the diameter of accepting the ring again.

Through adopting above-mentioned technical scheme, the tester inserts the barrel in the snap ring, accepts the ring butt to the snap ring on, can accomplish the installation of barrel, and the tester installs the barrel conveniently.

Optionally, the pressure piece comprises a pressure rod, and the diameter of the pressure rod is matched with the inner diameter of the cylinder; and an extension rod is arranged on the pressure rod in a threaded manner.

By adopting the technical scheme, the tester inserts the pressure rod into the cylinder from the top of the cylinder, so that pressure can be applied to the cement-based material in the cylinder, and the tester can conveniently apply pressure to the cement-based material in the cylinder; and through the installation of extension rod, be convenient for take out the pressure stick in the barrel after the test is accomplished.

Optionally, a clamping assembly for fixing the extension rod is arranged on the sliding seat, the clamping assembly comprises an extension plate, guide rods, clamping plates, a bidirectional screw rod and a second motor, the extension plate is arranged on the sliding seat, the guide rods are arranged on the extension plate, and the two clamping plates are arranged on the guide rods in a sliding manner; the bidirectional screw rod is rotatably arranged on the extension plate, and the bidirectional screw rod threads are arranged on the two clamping plates in a penetrating way, but the threads of the bidirectional screw rod threads arranged on the two clamping plates in a penetrating way are arranged in a reverse way; the second motor is arranged on the extension plate, and an output shaft of the second motor is coaxially connected with the bidirectional screw rod.

By adopting the technical scheme, the test of one horizontal plane is completed, when the sliding seat is driven to slide to the next horizontal plane by the first motor, the two clamping plates are driven to rotate by the second motor, so that the two clamping plates are mutually close to each other, the extension rod is clamped and fixed, at the moment, the pressure rod is used for canceling the application of pressure to the cement-based material in the cylinder, when the sliding seat slides to the next horizontal plane, the second motor is driven to reversely rotate, so that the two clamping plates are mutually far away, the clamping of the extension rod is relieved, at the moment, the pressure rod is used for applying pressure to the cement-based material in the cylinder again, and the problem of errors between the detection data and the actual use in the cement-based material test is further improved by fixing the pressure rod when the sliding seat slides to the next horizontal plane, so that the cutting of the cement-based material in the cylinder is realized; and through the installation of guide bar, when improving two slide gliding stability, prevent two splint and two-way screw rod synchronous rotation, and the condition of driving two splint to be close to each other or keep away from the difficulty appears.

In summary, the present application includes at least one of the following beneficial technical effects:

1. the prepared cement-based material is filled into the cylinder by a tester, then the pressure piece is placed into the cylinder to apply pressure to the cement-based material in the cylinder, meanwhile, the vertical driving assembly drives the upright post to horizontally slide on the workbench, the vertical driving assembly drives the sliding seat to slide in the sliding groove, so that the movement of the cement-based material in the cylinder in the 3D printing process can be simulated, the detection data of the cement-based material in the dynamic process of 3D printing can be obtained by observing the cement-based material extruded from the extrusion nozzle, and the problems of errors between the detection data in the cement-based material test and the actual use are effectively improved;

2. the method comprises the steps that when a first motor drives a sliding seat to slide to a next horizontal plane, a second motor drives a bidirectional screw rod to rotate, so that two clamping plates are close to each other, an extension rod is clamped and fixed, at the moment, a pressure rod cancels the application of pressure to cement-based materials in a cylinder, when the sliding seat slides to the next horizontal plane, the second motor is driven to rotate reversely, so that the two clamping plates are far away from each other, the clamping of the extension rod is relieved, at the moment, the pressure rod applies pressure to the cement-based materials in the cylinder again, and through the fixation of the pressure rod when the sliding seat slides to the next horizontal plane, the material breaking of the cement-based materials in the cylinder is realized, the extrusion condition of the cement-based materials in the 3D printing process is further simulated, and the problem of errors in detection data and actual use of the cement-based materials is further improved; and through the installation of guide bar, when improving two slide gliding stability, prevent two splint and two-way screw rod synchronous rotation, and the condition of driving two splint to be close to each other or keep away from the difficulty appears.

Drawings

Fig. 1 is a schematic structural view of a 3D printed cement-based material printability testing apparatus according to an embodiment of the present application.

Fig. 2 is an exploded schematic view of a barrel, pressure bar and extrusion nozzle of an embodiment of the present application.

Fig. 3 is a schematic structural view of a slide and clamp assembly according to an embodiment of the present application.

Reference numerals: 1. a work table; 2. a column; 21. a chute; 3. a slide; 4. a connecting frame; 41. a support rod; 42. a clasp; 5. a cylinder; 6. an extrusion nozzle; 7. a pressure member; 71. a pressure bar; 8. a lateral drive assembly; 81. a cylinder; 9. a vertical drive assembly; 91. a screw rod; 92. a first motor; 10. a guide rail; 11. a threaded joint; 12. a receiving ring; 13. an extension rod; 14. a clamping assembly; 141. an extension plate; 142. a guide rod; 143. a clamping plate; 144. a bidirectional screw; 145. a second motor; 15. and (5) receiving a tray.

Detailed Description

The present application is described in further detail below in conjunction with figures 1-3.

The embodiment of the application discloses a 3D prints cement-based material printability testing arrangement.

Referring to fig. 1, the 3d printing cement-based material printability testing apparatus includes a table 1, a column 2, a slider 3, a connection frame 4, a cylinder 5, an extrusion nozzle 6, and a pressure member 7; the inside of the cylinder 5 is hollow, and both ends of the cylinder are open, in this embodiment, the cylinder 5 is made of stainless steel, and has the characteristics of corrosion resistance, convenient cleaning, high strength and the like.

Referring to fig. 1, a stand column 2 is slidably mounted on a workbench 1, a chute 21 is formed in the stand column 2 along a vertical direction, a sliding seat 3 is slidably mounted in the chute 21, in this embodiment, the chute 21 is a T-shaped slot, and a portion of the sliding seat 3 located in the chute 21 is adapted to the T-shaped slot, so that the sliding seat 3 is more stable when sliding in the chute 21; the connecting frame 4 is arranged on the sliding seat 3, and the cylinder 5 is detachably arranged on the connecting frame 4; the extrusion nozzle 6 is detachably arranged at the bottom of the cylinder 5, and the pressure piece 7 is detachably arranged in the cylinder 5 and is used for applying pressure to cement-based materials in the cylinder 5; the workbench 1 is provided with a transverse driving component 8 for driving the upright post 2 to horizontally slide on the workbench 1; the upright 2 is provided with a vertical driving assembly 9 for driving the sliding seat 3 to slide in the sliding groove 21.

The tester loads the prepared cement-based material into the cylinder 5, then puts the pressure piece 7 into the cylinder 5 to apply pressure to the cement-based material in the cylinder 5, meanwhile, the transverse driving assembly 8 drives the upright post 2 to horizontally slide on the workbench 1, the vertical driving assembly 9 drives the sliding seat 3 to slide in the sliding groove 21, so that the movement of the cement-based material in the cylinder 5 in the 3D printing process can be simulated, the detection data of the cement-based material in the dynamic process of 3D printing can be obtained by observing the cement-based material extruded from the extrusion nozzle 6, and the problems of errors in the detection data and the actual use of the cement-based material in the test are effectively solved.

And in this embodiment, a receiving tray 15 is also placed on the working table 1, and the receiving tray 15 is located below the extrusion nozzle 6, so as to collect cement-based materials which are basic from the inside of the extrusion nozzle 6.

Referring to fig. 1, the lateral driving assembly 8 includes an air cylinder 81, the air cylinder 81 is mounted on the table 1, and a piston rod of the air cylinder 81 is connected with the column 2; two guide rails 10 are arranged on the workbench 1 along the expansion and contraction direction of a piston rod of the air cylinder 81, the two guide rails 10 and the workbench 1 jointly form a dovetail groove, the bottom of the upright post 2 is in a dovetail shape matched with the dovetail groove, and the upright post 2 slides in the dovetail groove formed by the two guide rails 10 and the workbench 1 jointly

The upright post 2 can be controlled to slide back and forth on the workbench 1 by controlling the extension or retraction of the piston rod of the air cylinder 81, and a tester drives the upright post 2 to slide back and forth on the workbench 1 conveniently; the guide rail 10 clamps the upright post 2 inside, so that the upright post 2 can only slide along the guide rail 10 in the length direction, and the sliding stability of the guide rail 10 on the workbench 1 is effectively improved.

Referring to fig. 1, the vertical driving assembly 9 includes a screw 91 and a first motor 92, the screw 91 is rotatably installed on the top wall of the chute 21, and the screw 91 is threaded on the slider 3; the first motor 92 is mounted on the column 2, and an output shaft of the first motor 92 is coaxially connected with the screw 91.

The output shaft of the first motor 92 drives the screw rod 91 to rotate, so that the sliding seat 3 slides in the sliding groove 21 along the length direction of the sliding groove 21, and the sliding seat 3 can slide in the sliding groove 21 conveniently by controlling the positive and negative rotation of the output shaft of the first motor 92 to realize the reciprocating sliding of the sliding seat 3 in the sliding groove 21.

Referring to fig. 1 and 2, a receiving ring 12 is installed on a barrel 5, the diameter of the receiving ring 12 is larger than that of the barrel 5, in this embodiment, the diameter of the receiving ring 12 gradually increases from the direction of approaching the barrel 5 to the direction of separating from the barrel 5, and the side wall of the receiving ring 12 gradually rises, so that the receiving ring 12 and the barrel 5 together form an accommodating space, and cement-based materials overflowed from the barrel 5 flow along the outer wall of the barrel 5 into the accommodating space formed by the receiving ring 12 and the barrel 5 to be collected, so that a tester can collect the cement-based materials overflowed from the barrel 5 conveniently;

the connecting frame 4 comprises a supporting rod 41 and a clamping ring 42, the supporting rod 41 is arranged on the sliding seat 3, the clamping ring 42 is arranged on the supporting rod 41, the inner diameter of the clamping ring 42 is matched with the outer diameter of the cylinder 5, but the inner diameter of the clamping ring 42 is smaller than the diameter of the receiving ring 12, a tester inserts the cylinder 5 into the clamping ring 42, the receiving ring 12 is abutted to the clamping ring 42, the installation of the cylinder 5 can be completed, and the tester installs the cylinder 5 conveniently; in this embodiment, two connecting frames 4 are installed on the sliding seat 3, so that stability of the cylinder 5 is improved when the sliding seat 3 moves.

Referring to fig. 1 and 2, one end of the cylinder 5, which is close to the workbench 1, is provided with a screwed joint 11 in a communicating manner, and the extrusion nozzle 6 is arranged on the screwed joint 11 in a screwed manner, so that the extrusion nozzle 6 is convenient to assemble and disassemble, and a tester can conveniently replace the extrusion nozzles 6 with different opening sizes.

Referring to fig. 2 and 3, the pressure member 7 comprises a pressure rod 71, the diameter of the pressure rod 71 being adapted to the inner diameter of the cylinder 5, in this embodiment the pressure rod 71 is likewise of stainless steel; and the pressure rod 71 is provided with an extension rod 13 in a threaded manner; the slide 3 is provided with a clamping assembly 14 for fixing the extension rod 13, the clamping assembly 14 comprises extension plates 141, guide rods 142, clamping plates 143, a bidirectional screw 144 and a second motor 145, the extension plates 141 are arranged on the slide 3 at intervals, the guide rods 142 are arranged between the two extension plates 141, and the clamping plates 143 are slidably arranged on the guide rods 142; the bidirectional screw 144 is rotatably installed on the extension plate 141, and the bidirectional screw 144 is threaded on the two clamping plates 143, but the threads of the bidirectional screw 144 threaded on the two clamping plates 143 are reversely arranged; the second motor 145 is mounted on the extension plate 141, and an output shaft of the second motor 145 is coaxially connected with the bidirectional screw 144.

After the test of one horizontal plane is completed, when the sliding seat 3 is driven to slide to the next horizontal plane by the first motor 92, the two clamping plates 143 are driven to rotate by the second motor 145, so that the two clamping plates 143 are mutually close to clamp and fix the extension rod 13, at the moment, the pressure rod 71 is used for canceling the application of pressure to the cement-based material in the cylinder 5, when the sliding seat 3 slides to the next horizontal plane, the second motor 145 is driven to reversely rotate, so that the two clamping plates 143 are mutually far away, the clamping of the extension rod 13 is relieved, at the moment, the pressure rod 71 is used for applying pressure to the cement-based material in the cylinder 5 again, and the problem of error between the detection data of the cement-based material and the actual use is further improved by fixing the pressure rod 71 when the sliding seat 3 slides to the next horizontal plane, the material breaking of the cement-based material in the cylinder 5 is realized, and the extrusion situation of the cement-based material in the 3D printing process is further simulated;

the pressure rod 71 is inserted into the cylinder 5 from the top of the cylinder 5 by a tester, so that pressure can be applied to the cement-based material in the cylinder 5, and the tester can conveniently apply pressure to the cement-based material in the cylinder 5; and the pressure rod 71 is conveniently taken out of the cylinder 5 after the test is finished through the installation of the extension rod 13;

and through the installation of guide bar 142, when improving two slide stability, prevent two splint 143 and the synchronous rotation of two-way screw rod 144, and the circumstances that drive two splint 143 to be close to each other or keep away from the difficulty appear.

The implementation principle of the 3D printing cement-based material printability testing device provided by the embodiment of the application is as follows: the tester connects the extrusion nozzle 6 with proper opening size to the screwed joint 11 through threads, then inserts the cylinder 5 into the snap ring 42, the receiving ring 12 on the cylinder 5 is abutted with the snap ring 42 to complete the installation of the cylinder 5, then the prepared cement-based material is loaded into the cylinder 5, the pressure rod 71 is inserted into the cylinder 5 to press the cement-based material in the cylinder 5, meanwhile, the cylinder 81 drives the upright post 2 to slide back and forth on the workbench 1 along the length direction of the guide rail 10, and the first motor 92 drives the screw 91 to rotate, so that the sliding seat 3 slides in the length direction of the sliding groove 21 in the sliding groove 21, and the movement of the cement-based material in the cylinder 5 in the 3D printing process is simulated; and when the slide 3 slides in the chute 21, the second motor 145 drives the bidirectional screw 144 to rotate, so that the two clamping plates 143 clamp and fix the extension rod 13, at the moment, the pressure rod 71 cancels the application of pressure to the cement-based material in the cylinder 5, and when the slide 3 slides to a proper height, the second motor 145 drives the two clamping plates 143 to release the fixation of the extension rod 13, thereby further simulating the breaking extrusion condition of the cement-based material in the 3D printing process, and improving the problem of errors between the detection data in the cement-based material test and the actual use.

The foregoing are all preferred embodiments of the present application, and are not intended to limit the scope of the present application in any way, therefore: all equivalent changes in structure, shape and principle of this application should be covered in the protection scope of this application.

Claims (9)

1. The utility model provides a 3D prints cement-based material printability testing arrangement which characterized in that: the automatic feeding device comprises a workbench (1), an upright post (2), a sliding seat (3), a connecting frame (4), a cylinder body (5), an extrusion nozzle (6) and a pressure piece (7), wherein the upright post (2) is arranged on the workbench (1) in a sliding manner, a sliding groove (21) is formed in the upright post (2) along the vertical direction, and the sliding seat (3) is arranged in the sliding groove (21) in a sliding manner; the connecting frame (4) is arranged on the sliding seat (3), the inside of the cylinder body (5) is hollow, two ends of the cylinder body are provided with openings, and the cylinder body (5) is detachably arranged on the connecting frame (4); the extrusion nozzle (6) is detachably arranged at the bottom of the cylinder (5), and the pressure piece (7) is detachably arranged in the cylinder (5) and is used for applying pressure to cement-based materials in the cylinder (5); the workbench (1) is provided with a transverse driving assembly (8) for driving the upright post (2) to horizontally slide on the workbench (1); the vertical driving assembly (9) for driving the sliding seat (3) to slide in the sliding groove (21) is arranged on the upright post (2).

2. The 3D printed cementitious material printability testing apparatus of claim 1, wherein: the transverse driving assembly (8) comprises an air cylinder (81), the air cylinder (81) is arranged on the workbench (1), and a piston rod of the air cylinder (81) is connected with the upright post (2).

3. The 3D printed cementitious material printability testing apparatus of claim 2, wherein: the workbench (1) is provided with a guide rail (10) along the expansion direction of a piston rod of the air cylinder (81), and the upright post (2) slides and is clamped in the guide rail (10).

4. The 3D printed cementitious material printability testing apparatus of claim 1, wherein: the vertical driving assembly (9) comprises a screw rod (91) and a first motor (92), the screw rod (91) is rotatably arranged on the top wall of the sliding groove (21), and the screw rod (91) is threaded on the sliding seat (3); the first motor (92) is arranged on the upright post (2), and an output shaft of the first motor (92) is coaxially connected with the screw rod (91).

5. The 3D printed cementitious material printability testing apparatus of claim 1, wherein: one end of the cylinder body (5) close to the workbench (1) is provided with a threaded joint (11), and the extrusion nozzle (6) is arranged on the threaded joint (11) in a threaded mode.

6. The 3D printed cementitious material printability testing apparatus of claim 1, wherein: the cylinder body (5) is provided with a bearing ring (12), and the diameter of the bearing ring (12) is larger than that of the cylinder body (5).

7. The 3D printed cementitious material printability testing apparatus of claim 6, wherein: the connecting frame (4) comprises a supporting rod (41) and a clamping ring (42), the supporting rod (41) is arranged on the sliding seat (3), the clamping ring (42) is arranged on the supporting rod (41), the inner diameter of the clamping ring (42) is matched with the outer diameter of the cylinder body (5), and the inner diameter of the clamping ring (42) is smaller than the diameter of the bearing ring (12).

8. The 3D printed cementitious material printability testing apparatus of claim 1, wherein: the pressure member (7) comprises a pressure rod (71), and the diameter of the pressure rod (71) is matched with the inner diameter of the cylinder (5); and an extension rod (13) is arranged on the pressure rod (71) in a threaded manner.

9. The 3D printed cementitious material printability testing apparatus of claim 8, wherein: the clamping assembly (14) for fixing the extension rod (13) is arranged on the sliding seat (3), the clamping assembly (14) comprises an extension plate (141), guide rods (142), clamping plates (143), a bidirectional screw rod (144) and a second motor (145), the extension plate (141) is arranged on the sliding seat (3), the guide rods (142) are arranged on the extension plate (141), and the clamping plates (143) are slidably arranged on the guide rods (142) in two ways; the bidirectional screw rod (144) is rotatably arranged on the extension plate (141), threads of the bidirectional screw rod (144) penetrate through the two clamping plates (143), and threads of the bidirectional screw rod (144) penetrating through the two clamping plates (143) are reversely arranged; the second motor (145) is arranged on the extension plate (141), and an output shaft of the second motor (145) is coaxially connected with the bidirectional screw rod (144).

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