A scattering test device suitable for asphalt concrete specimens

Abstract

The present invention belongs to the technical field of scattering test, and discloses a scattering test device suitable for asphalt concrete specimens, including a test box, a front side of the test box is sealed by a hinge joint, an observation window is provided on the front side of the sealed door, a rotating test mechanism is arranged inside the test box, the rotating test mechanism includes an adjusting base, and a rotation adjustment action of a concrete test block is achieved through the rotating test mechanism, so as to facilitate multi-directional scattering tests on the concrete test block, a friction pressure adjustment mechanism is arranged inside the test box, and the friction pressure adjustment mechanism includes a lifting plate. The present invention realizes automatic rotation adjustment of the concrete test block by arranging the rotating test mechanism, and performs friction scattering tests on the concrete test block in different directions by turning the concrete test block, which is more in line with actual usage conditions, thereby improving the accuracy of the experimental results.

Description

Technical Field

[0001] The invention belongs to the technical field of scattering test, in particular to a scattering experimental device suitable for asphalt concrete test pieces. Background Art

[0002] Asphalt concrete pavement is prone to road wear and asphalt mixture particle scattering under vehicle load, resulting in road potholes and other performances affecting the durability and driving comfort of asphalt pavement. The scattering loss of asphalt concrete pavement is its most important performance indicator. At present, the scattering performance evaluation of asphalt concrete pavement in my country is a scattering test using a scattering test device. The current scattering test device includes a frame, a horizontally arranged cylinder is rotatably connected to the frame, a motor is fixed on one side of the frame, the output shaft of the motor is coaxially fixed with the cylinder, and a door is hinged on the cylinder. When the staff needs to conduct a scattering test on the asphalt concrete pavement, they only need to place the concrete test block of the asphalt concrete pavement in the cylinder, turn on the motor, and drive the cylinder to rotate. Then the concrete test block will rub against the inner wall of the cylinder to simulate the degree of aggregate falling off and scattering on the pavement surface under the action of traffic load. However, the relative sliding and friction between the concrete test block and the inner wall of the cylinder is achieved by relying on the weight of the concrete test block itself and the rotation of the cylinder, and cannot well simulate the effect of traffic load, thereby reducing the efficiency of the asphalt concrete pavement scattering test.

[0003] For example, a Chinese patent document discloses a scattering test device suitable for asphalt concrete specimens (Announcement No.: CN215575149U). Although this patent places the concrete test block on a placement plate and then turns on the motor to drive the corresponding rotating roller to rotate, thereby rotating the conveyor belt, the conveyor belt can continuously rub against the concrete test block, thereby better simulating the traffic load.

[0004] However, the fixed setting of the placement plate means that the concrete test block can only be tested for friction in a single direction. Since the concrete pavement will be rubbed by vehicles in multiple directions during actual use, the accuracy of the single-direction test experiment is low. The friction test is carried out by driving the steel brush through the operation of the conveyor belt. When the friction between the steel brush and the concrete test block is large, the conveyor belt is prone to slipping, resulting in the problem that the degree of scattering of the asphalt concrete test block cannot be effectively tested under large pressure friction. Summary of the invention

[0005] In order to solve the problems raised in the above-mentioned background technology, the present invention provides a scattering test device suitable for asphalt concrete specimens, which has the function of automatically driving the concrete test block to rotate and adjust. By turning the concrete test block, the friction scattering test is carried out on the concrete test block in different directions, which is more in line with the actual use situation, thereby improving the accuracy of the experimental results, and realizing accurate specified pressure friction on the concrete test block. By subjecting the concrete test block to friction scattering under different pressures, the convenience of the experiment and the accuracy of the data results are improved.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a scattering test device suitable for asphalt concrete specimens, comprising a test box, the front of which is sealed by a hinge joint, an observation window is provided on the front of the sealed door, a rotating test mechanism is provided inside the test box, the rotating test mechanism comprises an adjustment base, and the rotating test mechanism is used to realize the rotation adjustment action of the concrete test block, thereby facilitating the multi-directional scattering test of the concrete test block;

[0007] A friction pressure regulating mechanism is arranged inside the test box, and the friction pressure regulating mechanism comprises a lifting plate. The friction pressure regulating mechanism is located above the rotating test mechanism, and the friction pressure regulating mechanism is used to implement friction scattering tests of concrete test blocks with different pressures.

[0008] Preferably, the lower surface of the adjustment base is fixedly connected to the inner bottom wall of the test box, a driving rod is installed on the upper surface of the adjustment base through a bearing, one end of the driving rod is fixedly connected to a concrete placement block, and an annular support groove is provided on the upper surface of the adjustment base, and the concrete placement block serves to place a concrete test block to be tested.

[0009] Preferably, the inner wall of the annular support slide groove is slidably connected with an arc-shaped slider distributed in an annular array, and the upper surfaces of multiple arc-shaped sliders are fixedly connected to the lower surface of the concrete placement block. The arc-shaped slider and the annular support slide groove cooperate with the concrete placement block to rotate stably and support the pressure on the concrete placement block. The other end of the driving rod passes through and extends to the interior of the adjustment base, and the other end of the driving rod has a driving wheel fixedly sleeved on the outer surface.

[0010] Preferably, the outer surface of the driving wheel is provided with arc-shaped limit grooves distributed in a circular array, and the arc-shaped limit grooves serve to limit the driving wheel. The outer surface of the driving wheel is provided with toggle grooves distributed in a circular array, and a servo motor is fixedly installed on the inner bottom wall of the adjustment base.

[0011] Preferably, the output shaft of the servo motor is fixedly mounted with a rotating shaft via a coupling, and the outer surface of the rotating shaft is respectively fixedly sleeved with a rotating disk and an arc-shaped limit disk, and the outer surface of the arc-shaped limit disk is in contact with the inner wall of one of the arc-shaped limit grooves, and the servo motor plays a role in synchronously driving the rotating disk and the arc-shaped limit disk to rotate through the rotating shaft.

[0012] Preferably, the upper surface of the rotating disk contacts the lower surface of the arc-shaped limit disk, a lever is fixedly connected to the upper surface of the rotating disk, and the inner wall of the lifting plate is movably sleeved with symmetrically distributed guide rods, one end of the two guide rods are fixedly connected to the inner top wall of the test box, and the rotating disk drives the lever to rotate in a circle.

[0013] Preferably, the other ends of the two guide rods are fixedly connected to the inner bottom wall of the test box, a travel groove is provided on the upper surface of the lifting plate, and a symmetrically distributed first hydraulic cylinder is fixedly installed on the inner top wall of the test box. The guide rods guide the lifting and lowering movement of the lifting plate and prevent the first hydraulic cylinder from being subjected to the pulling force of the lifting plate to the left and right.

[0014] Preferably, one end of the two first hydraulic cylinder piston rods are fixedly connected to the upper surface of the lifting plate, the lower surface of the lifting plate is fixedly connected with symmetrically distributed slide rails, the outer surface of the slide rails is slidably sleeved with a moving sleeve, the lower surfaces of the two moving sleeves are fixedly connected with a moving shell, and the slide rails and the moving sleeves cooperate with the moving shell to achieve stable movement.

[0015] Preferably, a pressure sensor is fixedly installed on the inner top wall of the movable shell, and symmetrically distributed limit slide grooves are provided on the inner walls on both sides of the movable shell. The inner walls of the limit slide grooves are slidably connected to limit sliders, and the opposite surfaces of the two limit sliders are fixedly connected with test blocks. The outer surface of the test block is movably connected to the inner wall of the movable shell. The pressure sensor plays a role of accurately displaying the pressure of the concrete test block during the flying test through the test block, and friction bumps distributed in a linear array are provided under the test block, so as to better fit the traffic load of simulated vehicles.

[0016] Preferably, the upper surface of the test block is fixedly connected with symmetrically distributed return springs, one ends of the two return springs are fixedly connected to the inner top wall of the moving shell, the upper surface of the moving shell is fixedly connected with a travel block, one end of the travel block passes through the travel groove and extends to the upper surface of the lifting plate, and a second hydraulic cylinder is fixedly installed on the upper surface of the lifting plate, one end of the piston rod of the second hydraulic cylinder is fixedly connected to one side surface of the travel block, the travel groove serves to guide the movement of the travel block and limit its travel, and the elastic force of the return spring serves to drive the test block to reset and move.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention realizes automatic rotation adjustment of the concrete test block by setting a rotation test mechanism. By turning the concrete test block, the friction and scattering test of the concrete test block is carried out in different directions, which is more in line with the actual use situation, thereby improving the accuracy of the experimental results.

[0019] 2. The present invention achieves accurate specified pressure friction on the concrete test block by setting a friction pressure adjustment mechanism, and improves the convenience of the experiment and the accuracy of the data results by rubbing the concrete test block under different pressures. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the present invention;

[0021] Figure 2 This is a three-dimensional diagram of the test box structure of the present invention;

[0022] Figure 3 This is a three-dimensional diagram of the adjustable base structure of the present invention;

[0023] Figure 4 This is a three-dimensional diagram of the driving wheel structure of the present invention;

[0024] Figure 5 This is a three-dimensional diagram of the lifting plate structure of the present invention;

[0025] Figure 6 It is a three-dimensional diagram of the movable shell structure of the present invention.

[0026] In the figure: 1. test box; 2. sealing door; 3. observation window; 4. adjustment base; 41. driving rod; 42. concrete placement block; 43. annular support slide; 44. arc-shaped slider; 45. driving wheel; 46. arc-shaped limit groove; 47. toggle groove; 48. servo motor; 49. rotating shaft; 410. rotating disk; 411. arc-shaped limit disk; 412. toggle rod; 5. lifting plate; 51. guide rod; 52. travel groove; 53. first hydraulic cylinder; 54. slide rail; 55. moving sleeve; 56. moving shell; 57. pressure sensor; 58. limit slide; 59. limit slider; 510. test block; 511. reset spring; 512. travel block; 513. second hydraulic cylinder. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0028] like Figures 1 to 6 As shown, the present invention provides a scattering test device suitable for asphalt concrete specimens, comprising a test box 1, a sealing door 2 is provided on the front of the test box 1 through a hinge joint, an observation window 3 is provided on the front of the sealing door 2, a rotating test mechanism is provided inside the test box 1, and the rotating test mechanism includes an adjustment base 4, and the rotating test mechanism is used to realize the rotation adjustment action of the concrete test block, so as to facilitate the multi-directional scattering test of the concrete test block;

[0029] A friction pressure regulating mechanism is arranged inside the test box 1, and the friction pressure regulating mechanism comprises a lifting plate 5. The friction pressure regulating mechanism is located above the rotating test mechanism, and the friction pressure regulating mechanism is used to implement friction scattering tests of concrete test blocks at different pressures.

[0030] The above scheme is adopted: through the coordinated use of the rotation test mechanism and the friction pressure adjustment mechanism, the concrete test block can be automatically driven to rotate and adjust, and the friction and scattering test of the concrete test block can be carried out in different directions by turning the concrete test block, which is more in line with the actual use situation, thereby improving the accuracy of the experimental results. In addition, by performing specified pressure friction on the concrete test block and performing friction and scattering on the concrete test block under different pressures, the convenience of the experiment and the accuracy of the data results are improved.

[0031] like Figure 1 , Figure 2 , Figure 3 and Figure 4As shown, the lower surface of the adjusting base 4 is fixedly connected to the inner bottom wall of the test box 1, and a driving rod 41 is installed on the upper surface of the adjusting base 4 through a bearing. One end of the driving rod 41 is fixedly connected to a concrete placement block 42. An annular support slide groove 43 is provided on the upper surface of the adjusting base 4. The inner wall of the annular support slide groove 43 is slidably connected with arc-shaped sliders 44 distributed in an annular array. The upper surfaces of multiple arc-shaped sliders 44 are all fixedly connected to the lower surface of the concrete placement block 42. The other end of the driving rod 41 passes through and extends to the interior of the adjusting base 4. The outer surface of the other end of the driving rod 41 is fixedly sleeved with a driving wheel 45. The driving wheel The outer surface of 45 is provided with arc-shaped limit grooves 46 distributed in a circular array, the outer surface of the driving wheel 45 is provided with toggle grooves 47 distributed in a circular array, a servo motor 48 is fixedly installed on the inner bottom wall of the adjustment base 4, and the output shaft of the servo motor 48 is fixedly installed with a rotating shaft 49 through a coupling, and the outer surface of the rotating shaft 49 is respectively fixedly sleeved with a rotating disk 410 and an arc-shaped limit disk 411, the outer surface of the arc-shaped limit disk 411 contacts the inner wall of one of the arc-shaped limit grooves 46, the upper surface of the rotating disk 410 contacts the lower surface of the arc-shaped limit disk 411, and the upper surface of the rotating disk 410 is fixedly connected with a toggle rod 412.

[0032] The above scheme is adopted: the servo motor 48 is started to drive the rotating shaft 49 to rotate one circle. The rotation of the rotating shaft 49 drives the rotating disk 410 and the arc-shaped limiting disk 411 to rotate. The rotation of the arc-shaped limiting disk 411 causes its outer side to break away from the limitation of the arc-shaped limiting groove 46. At the same time, the rotation of the rotating disk 410 drives the driving wheel 45 to rotate ninety degrees through the dial rod 412 inserted into the dial groove 47. When the rotation is completed, the arc-shaped limiting disk 411 is again in rotational contact with another arc-shaped limiting groove 46, thereby limiting the driving wheel 45. When the driving wheel 45 rotates ninety degrees, the driving wheel 45 drives the concrete test block in the concrete placement block 42 to rotate ninety degrees through the driving rod 41, and the annular support slide groove 43 and the arc-shaped sliding block 44 cooperate to rotate stably. At this time, the friction scattering experiment is performed on the concrete test block in another direction through the reciprocating movement of the test block 510. Through the friction scattering experiments in different directions, the traffic load of vehicles traveling in different directions can be better simulated, thereby improving the effect of improving the accuracy of the experiment.

[0033] like Figure 1 , Figure 2 , Figure 5 and Figure 6As shown, the inner wall of the lifting plate 5 is movably sleeved with symmetrically distributed guide rods 51, one end of the two guide rods 51 is fixedly connected to the inner top wall of the test box 1, and the other end of the two guide rods 51 is fixedly connected to the inner bottom wall of the test box 1. A travel groove 52 is provided on the upper surface of the lifting plate 5, and the inner top wall of the test box 1 is fixedly installed with symmetrically distributed first hydraulic cylinders 53, one end of the piston rods of the two first hydraulic cylinders 53 is fixedly connected to the upper surface of the lifting plate 5, and the lower surface of the lifting plate 5 is fixedly connected with symmetrically distributed slide rails 54, and the outer surface of the slide rail 54 is slidably sleeved with a moving sleeve 55, and the lower surfaces of the two moving sleeves 55 are fixedly connected with a moving shell 56, and the inner top wall of the moving shell 56 is fixedly installed with a pressure sensor 57, and the two ends of the moving shell 56 are fixedly installed. The side inner wall is provided with symmetrically distributed limit slide grooves 58, the inner wall of the limit slide groove 58 is slidably connected to the limit slider 59, the opposite surfaces of the two limit sliders 59 are fixedly connected with the test blocks 510, the outer surface of the test block 510 is movably connected to the inner wall of the moving shell 56, the upper surface of the test block 510 is fixedly connected with the symmetrically distributed return springs 511, one end of the two return springs 511 is fixedly connected to the inner top wall of the moving shell 56, the upper surface of the moving shell 56 is fixedly connected with the travel block 512, one end of the travel block 512 passes through the travel groove 52 and extends to the upper surface of the lifting plate 5, the upper surface of the lifting plate 5 is fixedly installed with the second hydraulic cylinder 513, and one end of the piston rod of the second hydraulic cylinder 513 is fixedly connected to one side surface of the travel block 512.

[0034] The above scheme is adopted: the piston rod of the first hydraulic cylinder 53 is started to extend, and the extension of the piston rod of the first hydraulic cylinder 53 drives the lifting plate 5 to move downward, thereby driving the test block 510 to move downward and contact the concrete test block through the moving shell 56. When the moving shell 56 continues to descend, the test block 510 moves through the cooperation of the limiting slider 59 and the limiting slide groove 58, and drives the reset spring 511 to contract. When the test block 510 moves to contact with the pressure sensor 57, the value displayed by the pressure sensor 57 can clearly observe the effect of the test block 510 on the concrete The extrusion pressure of the test block, when the test pressure value is reached, the first hydraulic cylinder 53 is stopped from extending, and the piston rod of the second hydraulic cylinder 513 is started to perform reciprocating telescopic motion. The reciprocating telescopic motion of the piston rod of the second hydraulic cylinder 513 drives the movable shell 56 to move back and forth through the stroke block 512, and the slide rail 54 and the movable sleeve 55 cooperate to move stably, thereby driving the bottom of the test block 510 and the top of the concrete test block to perform a reciprocating friction scattering experiment. During the experiment, the pressure can be continuously increased by extending the piston rod of the first hydraulic cylinder 53, so as to perform scattering experiments of different pressures on the concrete test block.

[0035] The working principle and use process of the present invention:

[0036] Step 1: During the experiment, a concrete test block is placed inside the concrete placing block 42, and then the sealing door 2 is closed and observed through the observation window 3 to prevent the concrete from scattering. The piston rod of the first hydraulic cylinder 53 is started to extend. The extension of the piston rod of the first hydraulic cylinder 53 drives the lifting plate 5 to move downward, thereby driving the test block 510 to move downward through the moving shell 56 and contact the concrete test block. When the moving shell 56 continues to descend, the test block 510 moves through the cooperation of the limiting slider 59 and the limiting slide groove 58, and drives the reset spring 511 to contract.

[0037] Step 2, when the test block 510 moves to contact with the pressure sensor 57, the value displayed by the pressure sensor 57 can clearly observe the squeezing force of the test block 510 on the concrete test block. When the test pressure value is reached, the first hydraulic cylinder 53 is stopped from extending, and the piston rod of the second hydraulic cylinder 513 is started to perform reciprocating telescopic motion. The reciprocating telescopic motion of the piston rod of the second hydraulic cylinder 513 drives the moving shell 56 to move back and forth through the stroke block 512, and the sliding rail 54 and the moving sleeve 55 cooperate to move stably, thereby driving the bottom of the test block 510 and the top of the concrete test block to perform a reciprocating friction scattering experiment. During the experiment, the pressure can be continuously increased by extending the piston rod of the first hydraulic cylinder 53, so as to perform scattering experiments of different pressures on its concrete test block;

[0038] Step 3, when the one-way experiment is completed, the servo motor 48 is started to drive the rotating shaft 49 to rotate one circle. The rotation of the rotating shaft 49 drives the rotating disk 410 and the arc-shaped limiting disk 411 to rotate. The rotation of the arc-shaped limiting disk 411 causes its outer side to break away from the limit of the arc-shaped limiting groove 46. At the same time, the rotation of the rotating disk 410 drives the driving wheel 45 to rotate ninety degrees through the insertion of the lever 412 into the toggle groove 47. When the rotation is completed, the arc-shaped limiting disk 411 rotates and contacts with another arc-shaped limiting groove 46 again, thereby limiting the driving wheel 45.

[0039] Step 4, when the driving wheel 45 rotates ninety degrees, the driving wheel 45 drives the concrete test block in the concrete placement block 42 to rotate ninety degrees through the driving rod 41, and stably rotates through the cooperation of the annular support slide groove 43 and the arc-shaped slider 44. At this time, the friction and scattering test of the concrete test block in another direction is carried out through the reciprocating movement of the test block 510. Through the friction and scattering tests in different directions, the traffic load of vehicles coming and going in different directions can be better simulated, thereby improving the effect of improving the accuracy of the experiment.

[0040] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0041] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A scattering test device suitable for asphalt concrete specimens, comprising a test box (1), characterized in that: The front of the test box (1) is provided with a sealed door (2) via a hinge joint, and an observation window (3) is provided on the front of the sealed door (2). A rotating test mechanism is provided inside the test box (1), and the rotating test mechanism includes an adjustment base (4). The rotating test mechanism is used to realize a rotation adjustment action on the concrete test block, thereby facilitating a multi-directional scattering test on the concrete test block. The test box (1) is provided with a friction pressure regulating mechanism inside, the friction pressure regulating mechanism comprising a lifting plate (5), the friction pressure regulating mechanism being located above the rotating test mechanism, and the friction pressure regulating mechanism being used to implement a friction scattering test of different pressures on a concrete test block; The lower surface of the adjustment base (4) is fixedly connected to the inner bottom wall of the test box (1); a driving rod (41) is installed on the upper surface of the adjustment base (4) via a bearing; one end of the driving rod (41) is fixedly connected to a concrete placement block (42); and an annular support slide groove (43) is provided on the upper surface of the adjustment base (4); The inner wall of the annular support slide groove (43) is slidably connected with arc-shaped sliding blocks (44) distributed in an annular array, and the upper surfaces of the plurality of arc-shaped sliding blocks (44) are fixedly connected to the lower surface of the concrete placement block (42); the other end of the driving rod (41) penetrates and extends to the inside of the adjustment base (4), and the outer surface of the other end of the driving rod (41) is fixedly sleeved with a driving wheel (45); The outer surface of the driving wheel (45) is provided with arc-shaped limiting grooves (46) distributed in a ring array, the outer surface of the driving wheel (45) is provided with toggle grooves (47) distributed in a ring array, and a servo motor (48) is fixedly mounted on the inner bottom wall of the adjustment base (4); The output shaft of the servo motor (48) is fixedly mounted with a rotating shaft (49) via a coupling, and the outer surface of the rotating shaft (49) is respectively fixedly sleeved with a rotating disk (410) and an arc-shaped limiting disk (411), and the outer surface of the arc-shaped limiting disk (411) contacts the inner wall of one of the arc-shaped limiting grooves (46); The upper surface of the rotating disk (410) contacts the lower surface of the arc-shaped limiting disk (411), the upper surface of the rotating disk (410) is fixedly connected to a lever (412), the inner wall of the lifting plate (5) is movably sleeved with symmetrically distributed guide rods (51), and one end of the two guide rods (51) is fixedly connected to the inner top wall of the test box (1); The other ends of the two guide rods (51) are fixedly connected to the inner bottom wall of the test box (1); a travel groove (52) is provided on the upper surface of the lifting plate (5); and symmetrically distributed first hydraulic cylinders (53) are fixedly installed on the inner top wall of the test box (1); One end of the piston rod of the two first hydraulic cylinders (53) is fixedly connected to the upper surface of the lifting plate (5), the lower surface of the lifting plate (5) is fixedly connected to symmetrically distributed slide rails (54), the outer surface of the slide rail (54) is slidably sleeved with a moving sleeve (55), and the lower surfaces of the two moving sleeves (55) are fixedly connected to a moving shell (56); A pressure sensor (57) is fixedly mounted on the inner top wall of the movable shell (56); symmetrically distributed limiting slide grooves (58) are provided on the inner walls of both sides of the movable shell (56); the inner walls of the limiting slide grooves (58) are slidably connected to limiting sliders (59); the opposing surfaces of the two limiting sliders (59) are fixedly connected to test blocks (510); the outer surface of the test block (510) is movably sleeved with the inner wall of the movable shell (56); The upper surface of the test block (510) is fixedly connected with symmetrically distributed return springs (511), one end of each of the two return springs (511) is fixedly connected to the inner top wall of the movable shell (56), the upper surface of the movable shell (56) is fixedly connected with a travel block (512), one end of the travel block (512) passes through the travel groove (52) and extends to the upper surface of the lifting plate (5), and a second hydraulic cylinder (513) is fixedly installed on the upper surface of the lifting plate (5), and one end of the piston rod of the second hydraulic cylinder (513) is fixedly connected to a side surface of the travel block (512).

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