A device for measuring the wet expansion force of a high-speed railway foundation

Abstract

The present invention discloses a device for measuring the wet expansion force of a high-speed rail foundation, which relates to the field of testing technology. It includes a test barrel, in which a hydraulic bladder is fixedly installed. A hydraulic pipe is connected to the hydraulic bladder. One side of the test barrel is hinged with a hinge rod, and a matching plate is hinged on the hinge rod. A test sample is placed in the test barrel, and the test sample is closely attached to the hydraulic bladder and the matching plate. A bottom sealing plate is fixedly installed on the lower side of the matching plate. The test barrel presses the bottom sealing plate to contact the bottom plate, and the matching plate is closely attached to the test sample. The hydraulic pipe and the hydraulic bladder are filled with liquid, and a pressure gauge is installed at the end of the hydraulic pipe. Adding water into the test barrel causes the test sample to expand and squeeze the hydraulic bladder, and the liquid in the hydraulic bladder squeezes the pressure machine through the hydraulic pipe to test the extrusion strength. The setting of the matching plate can adjust the space in the test barrel to adapt to different test samples.

Description

Technical Field

[0001] The present invention relates to the technical field of testing, and in particular to a device for measuring the wet expansion force of high-speed railway subgrades. Background Art

[0002] In the construction of high-speed railways, the stability of the subgrade directly affects the safety and service life of the line, and the wet expansion force is one of the important factors leading to subgrade deformation. High-speed railway subgrades are usually composed of expansive soils such as mudstone and clay. These soils will expand significantly after absorbing water, generating wet expansion force, which in turn causes problems such as uneven uplift of the subgrade and track deformation. Traditional subgrade monitoring mainly focuses on settlement and bearing capacity, but there are still deficiencies in the systematic measurement of wet expansion force. Especially in complex geological conditions, there is a lack of high-precision and real-time monitoring means for wet expansion force.

[0003] In terms of wet expansion force testing technology, existing methods mainly include laboratory tests and on-site monitoring. However, laboratory tests are difficult to fully simulate the humidity changes and load conditions of actual subgrades, and on-site monitoring devices often have problems such as complex installation, insufficient long-term stability, and large data discreteness. In addition, existing wet expansion force measuring devices are mostly designed for ordinary soils and have poor adaptability to the special working conditions of high-speed railway subgrades, resulting in difficulties in meeting the requirements of high-speed railway projects in terms of measurement accuracy and reliability. In existing laboratory tests, only samples of fixed size can be tested, and direct contact testing with a pressure sensor on the sample is not accurate. Summary of the Invention

[0004] To solve the above technical problems, the present invention discloses a device for measuring the wet expansion force of high-speed railway subgrades, which includes a test barrel. A hydraulic bladder is fixedly installed inside the test barrel, and a hydraulic pipe is connected to the hydraulic bladder. One side of the test barrel is hinged with a hinge rod, and a mating plate is hinged to the hinge rod. A test sample is placed in the test barrel, and the test sample is in close contact with the hydraulic bladder and the mating plate. A bottom sealing plate is fixedly installed under the mating plate. The test barrel presses the bottom sealing plate to contact the bottom plate, and the mating plate is pressed against the test sample. The hydraulic pipe and the hydraulic bladder are filled with liquid, and a pressure gauge is installed at the end of the hydraulic pipe. Through the above technical solution, adding water to the test barrel causes the test sample to expand and squeeze the hydraulic bladder. The liquid in the hydraulic bladder squeezes the pressure gauge through the hydraulic pipe to test the extrusion strength. The mating plate is provided to adjust the space inside the test barrel to adapt to different test samples.

[0005] Furthermore, a track plate is fixedly installed on the bottom plate. Suppression fixing ears are fixedly installed on both sides of the test barrel. A suppression shaft is slidably installed on the suppression fixing ears. A suppression plate is fixedly installed at the bottom of the suppression shaft, and the suppression plate contacts the track plate. A suppression spring is fixedly installed between the suppression fixing ears and the suppression shaft.

[0006] Furthermore, two vertical support plates are fixedly installed on the track slab, and transverse support plates are respectively and fixedly installed on the two vertical support plates. One end of one of the transverse support plates is rotatably equipped with a first pulley, and a first belt is installed on the first pulley. The two ends of the other transverse support plate are rotatably equipped with a second pulley, and a second belt is installed on the second pulley. A first side plate is fixedly installed on the first belt, and a second side plate is fixedly installed on the second belt. A clamping assembly is hinged between the second side plate and the first side plate. The clamping assembly clamps the test sample, and the test sample is vertically downward in its natural state.

[0007] Furthermore, a track is installed on the track slab, and a pressing plate is slidably installed on the track. In its natural state, the roller does not contact the bottom plate. The height of the matching plate is lower than that of the test barrel. The test sample moves along with the second belt and the first belt and is inserted into the test barrel, and the roller is pressed on the bottom plate. The bottom sealing plate contacts the bottom of the test barrel. Through the above technical solution, the test sample is automatically inserted into the test barrel and presses the test barrel downward. Finally, the bottom sealing plate fits with the bottom of the test barrel, the matching plate fits with the test sample, and the roller is driven to move on the bottom plate. Driven by the second belt and the first belt, the test sample can be automatically combined with the test barrel, and multiple test samples can be tested simultaneously.

[0008] Furthermore, a limit block is fixedly installed on the matching plate, and the upper end of the hinge rod contacts the limit block in its natural state.

[0009] Furthermore, the clamping assembly includes a fixed frame. Rotating shafts are fixedly installed at both ends of the fixed frame. The rotating shafts are hinged to the second side plate and the first side plate. The test sample is fixed in the third motor.

[0010] Furthermore, a clamping plate is slidably installed in the fixed frame. A fixing bolt is rotatably installed on the clamping plate. The fixing bolt cooperates with the fixed frame. Rotating the fixing bolt drives the clamping plate to squeeze the test sample.

[0011] Furthermore, a fixing plate is fixedly installed at the upper end of the fixed frame, and an extrusion plate is fixedly installed on the lower side of the fixing plate. The extrusion plate contacts the upper part of the test sample. A water pipe is fixedly installed in the fixing plate and the extrusion plate, and the water pipe penetrates through the extrusion plate. Through the above technical solution, the clamping plate in the fixed frame can clamp the test sample, and the test sample can be injected with water through the water pipe to simulate the wet expansion of the test sample.

[0012] Furthermore, two third pulleys are rotatably installed at both ends of the horizontal support plate. The center distance between the two third pulleys is the same as that between the two first pulleys and is arranged in a staggered manner. A third belt is installed on the third pulley, and a third side plate is fixedly installed on the third belt. A connecting rod is hinged on the third side plate. A fixed block is fixedly installed on the rotating shaft, and the fixed block is fixedly connected to the connecting rod, and the connecting rod always maintains a horizontal state. Through the above technical solution, the third belt and the third belt arranged in a staggered manner can keep the connecting rod horizontal, thereby keeping the test sample vertical. The test sample being vertical ensures accurate insertion into the test barrel and can drive the test barrel to move while maintaining a vertical state.

[0013] Furthermore, a short support plate is fixedly installed on the vertical support plate, and a second motor is fixedly installed on the short support plate to drive the third pulley. A third motor is fixedly installed on the side of the horizontal support plate. An end face gear is fixedly installed on the second pulley, and the end face gear meshes with the driving gear. A first motor is fixedly installed on the horizontal support plate to drive the first pulley.

[0014] The beneficial effects of the present invention compared with the prior art are as follows:

[0015] (1) Through the above technical solution, water is added to the test barrel so that the test sample expands and squeezes the hydraulic bladder. The liquid in the hydraulic bladder squeezes the press through the hydraulic pipe to test the extrusion strength. The setting of the matching plate can adjust the space in the test barrel to adapt to different test samples.

[0016] (2) Through the above technical solution, the test sample is automatically inserted into the test barrel and presses down on the test barrel. Finally, the bottom sealing plate fits with the bottom of the test barrel, the matching plate fits with the test sample, and drives the rollers to move on the bottom plate. Through the drive of the second belt and the first belt, the test sample can be automatically combined with the test barrel, and multiple test samples can be tested simultaneously.

[0017] (3) Through the above technical solution, the clamping plate in the fixed frame can clamp the test sample, and the test sample can be injected with water through the water pipe to simulate the wet expansion of the test sample.

[0018] (4) Through the above technical solution, the third belt and the third belt arranged in a staggered manner can keep the connecting rod horizontal, thereby keeping the test sample vertical. The test sample being vertical ensures accurate insertion into the test barrel and can drive the test barrel to move while maintaining a vertical state. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the overall structure of a high-speed rail foundation wet expansion force measuring device according to an embodiment of the present invention Figure 1 。

[0020] Figure 2Schematic diagram of the overall structure of a device for measuring the wet expansion force of a high - speed rail foundation in an embodiment of the present invention Figure 2 。

[0021] Figure 3 Schematic diagram of some parts of a device for measuring the wet expansion force of a high - speed rail foundation in an embodiment of the present invention.

[0022] Figure 4 Schematic diagram of the test component of a device for measuring the wet expansion force of a high - speed rail foundation in an embodiment of the present invention.

[0023] Figure 5 Schematic diagram of the clamping component of a device for measuring the wet expansion force of a high - speed rail foundation in an embodiment of the present invention Figure 1 。

[0024] Figure 6 Schematic diagram of the clamping component of a device for measuring the wet expansion force of a high - speed rail foundation in an embodiment of the present invention Figure 2 。

[0025] Reference numerals in the attached drawings: 1 - bottom frame; 2 - bottom plate; 3 - vertical support plate; 4 - horizontal support plate; 5 - first motor; 6 - first pulley; 7 - second pulley; 8 - third pulley; 9 - third belt; 10 - third side plate; 11 - second belt; 12 - first belt; 13 - connecting rod; 14 - second side plate; 15 - first side plate; 16 - short support plate; 17 - second motor; 18 - third motor; 19 - driving gear; 20 - end face gear; 21 - rotating shaft; 22 - fixing block; 23 - fixing plate; 24 - extrusion plate; 25 - water - passing pipe; 26 - fixing bolt; 27 - clamping plate; 28 - fixing frame; 29 - test sample; 30 - test barrel; 31 - pressing plate; 32 - pressing fixing ear; 33 - hydraulic pipe; 34 - pressing spring; 35 - pressing shaft; 36 - hydraulic bladder; 37 - hinge shaft; 38 - limiting block; 39 - hinge rod; 40 - mating plate; 41 - bottom sealing plate; 42 - roller; 43 - track plate. Detailed implementation manners

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0027] Such as Figures 1 - 6A device for measuring the wet expansion force of a high-speed railway foundation as shown includes a bottom plate 2. A bottom frame 1 is fixedly installed on the bottom plate 2. A track plate 43 is fixedly installed on the bottom frame 1. Three pulley assemblies are installed on the track plate 43. In other embodiments, they can also be sprocket assemblies. Two of them are arranged concentrically side by side, and the other is arranged offset. A clamping assembly is installed between the two concentrically arranged pulley assemblies. A test assembly is installed on the track plate 43. The test sample 29 is driven by the pulley to be inserted into the test assembly for testing.

[0028] In this embodiment, a track plate 43 is fixedly installed on the bottom plate 2. A bottom frame 1 is fixedly installed between the bottom plate 2 and the track plate 43. Two vertical support plates 3 are fixedly installed on the track plate 43. Transverse support plates 4 are respectively fixedly installed on the two vertical support plates 3. A first pulley 6 is rotatably installed at both ends of one of the transverse support plates 4. A first belt 12 is installed on the first pulley 6. A second pulley 7 is rotatably installed at both ends of the other transverse support plate 4. A second belt 11 is installed on the second pulley 7. A first side plate 15 is fixedly installed on the first belt 12. A second side plate 14 is fixedly installed on the second belt 11. A clamping assembly is hinged between the second side plate 14 and the first side plate 15. The clamping assembly clamps the test sample 29. The test sample 29 is vertically downward in the natural state. The first pulley 6 and the second pulley 7 are coaxially installed but driven separately. There is no connection between the first pulley 6 and the second pulley 7. The test sample 29 installed between the first pulley 6 and the second pulley 7 has to move between the first pulley 6 and the second pulley 7 without being interfered.

[0029] In this embodiment, two third pulleys 8 are rotatably installed at both ends of the transverse support plate 4. The center distance between the two third pulleys 8 is the same as the center distance between the two first pulleys 6 and is arranged offset. A third belt 9 is installed on the third pulley 8. A third side plate 10 is fixedly installed on the third belt 9. There are multiple third side plates 10, and the number is the same as the number of the second side plates 14 and the first side plates 15. There are also multiple second side plates 14 and first side plates 15. Thus, multiple clamping assemblies can be installed. A connecting rod 13 is hinged on the third side plate 10. A fixing block 22 is fixedly installed on the rotating shaft 21. The fixing block 22 is fixedly connected with the connecting rod 13. The connecting rod 13 always remains horizontal. The offset third belts 9 and the third belts 9 can keep the connecting rod 13 horizontal, and further keep the test sample 29 vertical. Keeping the test sample 29 vertical ensures accurate insertion into the test barrel 30 and can drive the test barrel 30 to move in the vertical state. A short support plate 16 is fixedly installed on the vertical support plate 3. A second motor 17 for driving the third pulley 8 is fixedly installed on the short support plate 16. A third motor 18 is fixedly installed on the side of the transverse support plate 4. An end face gear 20 is fixedly installed on the second pulley 7. The end face gear 20 meshes with the driving gear 19. A first motor 5 for driving the first pulley 6 is fixedly installed on the transverse support plate 4.

[0030] Specifically, in this embodiment, the test component includes a test barrel 30. The test barrel 30 has a hollow structure with an opening on one side. A hydraulic bladder 36 is fixedly installed inside the test barrel 30. A hydraulic pipe 33 is connected to the hydraulic bladder 36. On the opening side of the test barrel 30, there is a hinged rod 39. Specifically, a hinge shaft 37 is fixedly installed on the test barrel 30, and the hinged rod 39 is hinged on the hinge shaft 37. A mating plate 40 is hinged on the hinged rod 39. There are two hinge shafts 37 and hinged rods 39. The upper and lower ends of the mating plate 40 are respectively hinged to the two hinged rods 39, forming a parallelogram linkage structure. A test sample 29 is placed inside the test barrel 30, and the test sample 29 is in close contact with the hydraulic bladder 36 and the mating plate 40. A bottom sealing plate 41 is fixedly installed on the lower side of the mating plate 40. The test barrel 30 presses down the bottom sealing plate 41 to contact the bottom plate 2. The mating plate 40 is pressed tightly against the test sample 29. The hydraulic pipe 33 and the hydraulic bladder 36 are filled with liquid, and a pressure gauge is installed at the end of the hydraulic pipe 33. Water is added to the test barrel 30 to cause the test sample 29 to expand and squeeze the hydraulic bladder 36. The liquid in the hydraulic bladder 36 squeezes the pressure gauge through the hydraulic pipe 33 to test the extrusion strength. The mating plate 40 is provided to be able to adjust the space inside the test barrel 30 to adapt to different test samples 29. Suppression fixing ears 32 are fixedly installed on both sides of the test barrel 30. A suppression shaft 35 is slidably installed on the suppression fixing ears 32. A suppression plate 31 is fixedly installed at the bottom of the suppression shaft 35. The suppression plate 31 contacts the track plate 43. A suppression spring 34 is fixedly installed between the suppression fixing ears 32 and the suppression shaft 35.

[0031] In this embodiment, a track is installed on the track plate 43, and the suppression plate 31 is slidably installed on the track. In the natural state, the roller 42 does not contact the bottom plate 2. The height of the mating plate 40 is lower than that of the test barrel 30. The test sample 29 moves along with the second belt 11 and the first belt 12 and is inserted into the test barrel 30, and presses the roller 42 against the bottom plate 2. The bottom sealing plate 41 contacts the bottom of the test barrel 30. The test sample 29 is automatically inserted into the test barrel 30 and presses down the test barrel 30. Finally, the bottom sealing plate 41 fits with the bottom of the test barrel 30, the mating plate 40 fits with the test sample 29, and drives the roller 42 to move on the bottom plate 2. Driven by the second belt 11 and the first belt 12, the test sample 29 can be automatically combined with the test barrel 30, and multiple test samples 29 can be tested simultaneously. A limit block 38 is fixedly installed on the mating plate 40. In the natural state, the upper end of the hinged rod 39 contacts the limit block 38.

[0032] The clamping assembly includes a fixed frame 28, which is a square frame structure. The two ends of the fixed frame 28 are fixedly provided with a rotating shaft 21, which is hinged with the second side plate 14 and the first side plate 15. The test sample 29 is fixed in the third motor 18. A clamping plate 27 is slidably provided in the fixed frame 28, and a fixing bolt 26 is rotatably provided on the clamping plate 27. The fixing bolt 26 cooperates with the fixed frame 28, and the rotating fixing bolt 26 drives the clamping plate 27 to squeeze the test sample 29. A fixed plate 23 is fixedly provided on the upper end of the fixed frame 28, and an extrusion plate 24 is fixedly provided on the lower side of the fixed plate 23. The extrusion plate 24 contacts the upper part of the test sample 29. A water pipe 25 is fixedly provided in the fixed plate 23 and the extrusion plate 24, and the water pipe 25 passes through the extrusion plate 24. Water is injected into the fixing frame 28 through the squeezing plate 24 to allow the test sample 29 to absorb and expand. The clamping plate 27 in the fixing frame 28 can clamp the test sample 29, and water can be injected into the test sample 29 through the water pipe 25 to simulate the swelling of the test sample 29.

[0033] Working principle: prepare multiple test components and place them on one side of the track plate 43. In the natural state, the pressure plate 31 contacts the track plate 43 and is supported by the pressure spring 34. The roller 42 leaves the bottom plate 2 and the bottom blocking plate 41 does not contact the test barrel 30. At the same time, the top height of the limit block 38 is lower than the top of the test barrel 30, and the matching plate 40 is also in a naturally drooping state. Then open the fixing plate 23, place the test sample 29 in the fixing frame 28, tighten the fixing bolts 26, and let the clamping plate 27 press the test sample 29. Then fix the fixing plate 23 to the fixing frame 28 with bolts, start all motors, and drive the clamping assembly to move. At this time, the clamping assembly follows the second side plate 14 and the first side plate 15 to move, and the test sample 29 is always kept vertically downward through the connection of the staggered third side plate 10 and the connecting rod 13. Manually place the test component on the track plate 43, and then the test sample 29 gradually lowers its height and just enters the test barrel 30 from the upper side of the matching plate 40. In the test barrel 30, due to the low height of the matching plate 40, the test sample 29 will contact the hydraulic bag 36 in the test barrel 30, driving the test barrel 30 to move until the lower end of the fixed frame 28 contacts the upper end of the test barrel 30, and starts to press the test barrel 30 downward, and finally the roller 42 contacts and rolls with the bottom plate 2, the bottom blocking plate 41 fits with the bottom of the test barrel 30, and with the cooperation of the hinged rod 39, the matching plate 40 also presses the test sample 29, and the test assembly is manually placed to cooperate with the test samples 29 of multiple clamping assemblies, and finally stops, and water is passed into the water pipe 25. After control, the test sample 29 can begin to expand, and the liquid in the hydraulic bag 36 is squeezed during the expansion process. The liquid in the hydraulic bag 36 is squeezed through the hydraulic pipe 33 to squeeze the pressure gauge for measurement. In this process, the test sample 29 is installed in other clamping assemblies. After the test is completed, the start motor drives the test assembly to leave the track plate 43 through the pulley assembly, and then the new test sample 29 is tested with the test assembly.

[0034] Only some exemplary embodiments of the present invention have been described above by way of illustration. Without doubt, for those of ordinary skill in the art, various different ways can be used to modify the described embodiments without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A high-speed railway foundation swelling force measuring device, characterized in that: The test barrel (30) comprises a test barrel (30), wherein a hydraulic bag (36) is fixedly installed inside the test barrel (30), and the hydraulic bag (36) is connected to a hydraulic pipe (33). A hinged rod (39) is hingedly connected to one side of the test barrel (30), and a matching plate (40) is hingedly connected to the hinged rod (39). A test sample (29) is placed in the test barrel (30), and the test sample (29) is closely attached to the hydraulic bag (36) and the matching plate (40). A bottom blocking plate (41) is fixedly installed on the lower side of the matching plate (40). The test barrel (30) presses the bottom blocking plate (41) downward to contact the bottom plate (2), and the matching plate (40) is closely attached to the test sample (29). The hydraulic pipe (33) and the hydraulic bag (36) are filled with liquid, and a pressure gauge is installed at the end of the hydraulic pipe (33); A track plate (43) is fixedly mounted on the bottom plate (2), two vertical support plates (3) are fixedly mounted on the track plate (43), and transverse support plates (4) are respectively fixedly mounted on the two vertical support plates (3), first pulleys (6) are rotatably mounted at both ends of one of the transverse support plates (4), and a first belt (12) is mounted on the first pulley (6), and second pulleys (7) are rotatably mounted at both ends of the other transverse support plate (4), and a second belt (11) is mounted on the second pulley (7), a first side plate (15) is fixedly mounted on the first belt (12), and a second side plate (14) is fixedly mounted on the second belt (11), and a clamping assembly is hingedly connected between the second side plate (14) and the first side plate (15), and the clamping assembly clamps the test sample (29), and the test sample (29) is vertically downward in a natural state; The clamping assembly comprises a fixed frame (28), with rotating shafts (21) fixedly mounted at both ends of the fixed frame (28), and the rotating shafts (21) are hingedly connected to the second side plate (14) and the first side plate (15); Two third pulleys (8) are rotatably mounted at both ends of one of the transverse support plates (4); the center distance between the two third pulleys (8) is the same as the center distance between the two first pulleys (6) and the third pulleys (8) are staggered; a third belt (9) is mounted on the third pulley (8); a third side plate (10) is fixedly mounted on the third belt (9); a connecting rod (13) is hingedly mounted on the third side plate (10); a fixed block (22) is fixedly mounted on the rotating shaft (21); the fixed block (22) is fixedly connected to the connecting rod (13); and the connecting rod (13) always maintains a horizontal state.

2. A high-speed railway foundation swelling force measuring device according to claim 1, characterized in that: The test barrel (30) is fixedly provided with a suppression fixing ear (32) on both sides, a suppression shaft (35) is slidably provided on the suppression fixing ear (32), a suppression plate (31) is fixedly provided at the bottom of the suppression shaft (35), the suppression plate (31) is in contact with the track plate (43), and a suppression spring (34) is fixedly provided between the suppression fixing ear (32) and the suppression shaft (35).

3. A high-speed railway foundation swelling force measuring device according to claim 1, characterized in that: The track plate (43) is provided with a track, and a pressing plate (31) is slidably provided on the track. In a natural state, the roller (42) does not contact the bottom plate (2), and the matching plate (40) is lower than the test barrel (30). The test sample (29) moves along with the second belt (11) and the first belt (12) to be inserted into the test barrel (30), and the roller (42) is pressed against the bottom plate (2), and the bottom blocking plate (41) is in contact with the bottom of the test barrel (30).

4. A high-speed railway foundation swelling force measuring device according to claim 3, characterized in that: A limit block (38) is fixedly mounted on the matching plate (40), and the upper end of the hinged rod (39) contacts the limit block (38) in a natural state.

5. A high-speed railway foundation expansion force measuring device according to claim 4, characterized in that: A clamping plate (27) is slidably mounted in the fixing frame (28), and a fixing bolt (26) is rotatably mounted on the clamping plate (27). The fixing bolt (26) cooperates with the fixing frame (28), and the rotating fixing bolt (26) drives the clamping plate (27) to squeeze the test sample (29).

6. A high-speed railway foundation expansion force measuring device according to claim 5, characterized in that: A fixing plate (23) is fixedly mounted on the upper end of the fixing frame (28), an extrusion plate (24) is fixedly mounted on the lower side of the fixing plate (23), the extrusion plate (24) contacts the upper part of the test sample (29), and a water pipe (25) is fixedly mounted inside the fixing plate (23) and the extrusion plate (24), the water pipe (25) passes through the extrusion plate (24).

7. A high-speed railway foundation swelling force measuring device according to claim 6, characterized in that: A short support plate (16) is fixedly mounted on the vertical support plate (3), a second motor (17) is fixedly mounted on the short support plate (16) for driving a third pulley (8), a third motor (18) is fixedly mounted on the side of the transverse support plate (4), an end gear (20) is fixedly mounted on the second pulley (7), the end gear (20) is meshed with a driving gear (19), and a first motor (5) is fixedly mounted on the transverse support plate (4) for driving the first pulley (6).

Images