Asphalt deformation resistance detection device for asphalt pavement detection

Abstract

The utility model discloses an asphalt deformation resistance detection device for asphalt pavement detection, which comprises a guide frame, a slide block is arranged on the inner side of the guide frame, the slide block moves back and forth along the inside of the guide block, and the bottom end of the slide block is rotatably connected with a pinch roller; a screw rod is arranged in the middle of the guide frame, the screw rod is in threaded connection with the sliding block, a motor is arranged at the rear end of the guide frame, and the output end of the motor is connected with the screw rod; a mounting frame is arranged over the guide frame, a plurality of air cylinders are arranged on the mounting frame, and the output ends of the air cylinders penetrate through the mounting frame to be connected with the guide frame and used for driving the guide frame to move up and down. The sliding block is installed in the guide frame, the pressing wheel is arranged at the bottom of the sliding block, then the guide frame is driven by the air cylinder to move downwards, the pressing wheel is pressed on the ground, certain pressure is applied to the pressing wheel, then the screw is driven by the motor to rotate, the sliding block and the pressing wheel move back and forth on the road surface, and the state that the wheel rolls the asphalt road surface is simulated.

Description

Technical Field

[0001] This utility model relates to the technical field of deformation resistance testing equipment, specifically an asphalt deformation resistance testing device for asphalt pavement testing. Background Technology

[0002] In road construction, asphalt pavement is widely used due to its advantages such as good smoothness, skid resistance, and driving comfort. However, over long-term use, asphalt pavement is affected by various factors such as vehicle load, temperature changes, and rainwater erosion, leading to a gradual decline in the performance of asphalt. Among these factors, the deformation resistance of asphalt is one of the key indicators for measuring its durability.

[0003] In the prior art, utility model patent with publication number CN218157369U discloses an asphalt deformation resistance testing device. The device includes a base, with vertical plates respectively arranged on the left and right sides of the upper end of the base. A mounting plate driven to lift and lower by a first driving mechanism is slidably connected between the two vertical plates. A rotating rod driven to rotate by a motor is arranged at the lower end of the mounting plate along the left and right direction. Multiple inwardly recessed mounting grooves are arranged on the rotating rod from left to right. Each mounting groove is provided with a journal, and a mounting rod is rotatably mounted on each journal. A lifting rod is hinged to the lower end of each mounting rod. An insert groove is provided at the lower end of the lifting rod, and a connecting column is slidably connected in the insert groove. A spring is provided between the connecting column and the insert groove, and a detection pressure plate is provided at the lower end of the connecting column.

[0004] The asphalt deformation resistance testing device provided by the aforementioned patent can simultaneously test multiple testing points, improving testing efficiency. However, in practice, deformation resistance testing of asphalt pavements is mostly conducted using testing equipment to perform compaction tests on asphalt specimens. The aforementioned asphalt deformation resistance testing equipment is primarily used for laboratory testing of asphalt specimens and cannot perform on-site deformation resistance testing of asphalt pavements. Utility Model Content

[0005] The purpose of this invention is to provide an asphalt deformation resistance testing device for asphalt pavement testing, which aims to improve the problem that existing asphalt deformation resistance testing equipment is mostly used to test asphalt specimens in the laboratory and cannot perform asphalt deformation resistance testing on asphalt pavement on-site.

[0006] This utility model is implemented as follows:

[0007] An asphalt deformation resistance testing device for asphalt pavement testing includes a guide frame, a slider inside the guide frame that moves back and forth along the inside of the guide frame, and a pressure roller rotatably connected to the bottom end of the slider; a screw in the middle of the guide frame that is threadedly connected to the slider; a motor at the rear end of the guide frame that is connected to the screw at its output end; and a mounting frame above the guide frame that has multiple cylinders mounted on it, the output ends of which pass through the mounting frame and are connected to the guide frame to drive the guide frame to move up and down.

[0008] Preferably, the guide frame has symmetrical grooves on both sides inside, and connecting plates are symmetrically provided on both sides of the top of the guide frame. The connecting plates are provided with multiple connecting holes, and a first bearing is provided in the middle of the front and rear end faces of the guide frame.

[0009] Preferably, the slider has rollers symmetrically arranged on both sides, and the rollers are inserted into the groove; the slider has a threaded hole in the middle, and ear plates are symmetrically arranged on both sides of the bottom surface of the slider, with a second bearing on each of the ear plates.

[0010] Preferably, the pressure roller integrates a pressure sensor and a displacement sensor, which are used to sense the applied pressure and detect the deformation of the asphalt pavement. Both ends of the pressure roller are provided with connecting shafts, which are interference-fitted with bearings. The outer end of the connecting shaft is provided with a first connecting line, and the end of the first connecting line is provided with a first connecting plug.

[0011] Preferably, both ends of the screw are provided with adapter shafts, and the end of the screw facing the motor is provided with a drive slot.

[0012] Preferably, the motor output end is provided with a drive shaft, which is inserted into a drive slot; one end of the motor that fits against the guide frame is provided with a fixing foot, and a second connecting line is provided on the side of the motor, with a second connecting plug at the end of the second connecting line.

[0013] Preferably, the mounting frame has a mounting plate aligned with the cylinder on its inner side, and the mounting plate has a through hole in the middle; the mounting frame has multiple bolt holes at its rear end.

[0014] Preferably, the cylinder is fitted with mounting feet symmetrically on both sides of one end of the mounting plate, and the mounting feet are provided with multiple mounting holes; the cylinder output end is provided with a telescopic rod, the bottom end of the telescopic rod is provided with a foot, the foot is provided with multiple bottom holes, and the foot is connected to the guide frame by bolts.

[0015] Preferably, the guide frame is provided with guide rods at the top of both the front and rear ends, and the mounting frame is provided with guide holes at the positions of the guide rods at both the front and rear ends, and a limiting end plate is provided at the end of the guide rod that passes through the guide hole.

[0016] Compared with the prior art, the beneficial effects of this utility model are:

[0017] 1. This utility model installs a slider inside the guide frame, and a pressure roller is set at the bottom of the slider. Then, the guide frame is driven to move down by a cylinder, so that the pressure roller is pressed against the ground and a certain pressure is applied to the pressure roller. Then, the screw is driven by a motor to rotate, so that the slider and the pressure roller move back and forth on the road surface to simulate the state of a wheel rolling on an asphalt road surface. The pressure roller is equipped with a displacement sensor and a pressure sensor. The deformation of the asphalt road surface can be determined by the data fed back by the pressure sensor.

[0018] 2. This utility model has guide rods at both the front and rear ends of the top of the guide frame. The guide rods enable the guide frame to move stably up and down along the mounting frame, facilitating the flexible use of the guide frame. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0020] Figure 2 This is a schematic diagram of the structure of the guide frame of this utility model;

[0021] Figure 3 This is a schematic diagram of the slider of this utility model;

[0022] Figure 4 This is a schematic diagram of the structure of the pressure roller of this utility model;

[0023] Figure 5 This is a schematic diagram of the screw structure of this utility model;

[0024] Figure 6 This is a schematic diagram of the structure of the motor of this utility model;

[0025] Figure 7 This is a schematic diagram of the installation frame of this utility model;

[0026] Figure 8 This is a schematic diagram of the structure of the cylinder of this utility model.

[0027] In the diagram: 1. Guide frame; 11. Slide groove; 12. Connecting plate; 13. Connecting hole; 14. First bearing; 15. Guide rod; 16. Limiting end plate; 2. Slider; 21. Threaded hole; 22. Roller; 23. Ear plate; 24. Second bearing; 3. Pressure roller; 31. Connecting shaft; 32. First connecting line; 33. First connecting plug; 4. Screw; 41. Adapter shaft; 42. Drive slot; 5. Motor; 51. Drive insertion shaft; 52. Fixed foot; 53. Second connecting line; 54. Second connecting plug; 6. Mounting frame; 61. Guide hole; 62. Mounting plate; 63. Through hole; 64. Bolt hole; 7. Cylinder; 71. Mounting foot; 72. Mounting hole; 73. Telescopic rod; 74. Base foot; 75. Bottom hole. Detailed implementation method:

[0028] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details:

[0030] Example 1

[0031] like Figure 1 As shown, an asphalt pavement deformation testing device includes a guide frame 1. A slider 2 is located inside the guide frame 1, and the slider 2 moves back and forth along the inside of the guide frame. The guide frame 1, in conjunction with the slider 2, facilitates the slider 2's movement back and forth within the guide frame 1. A pressure roller 3 is rotatably connected to the bottom end of the slider 2; the slider 2 drives the pressure roller 3 to move back and forth, thereby achieving the purpose of compacting the pavement. A screw 4 is located in the middle of the guide frame 1, and the screw 4 is threadedly connected to the slider 2. A motor 5 is located at the rear end of the guide frame 1, and the output end of the motor 5 is connected to the screw 4. This structure facilitates the rotation of the screw 4 by the motor 5, causing the screw 4 to drive the slider 2 to move back and forth along the inside of the guide frame 1, facilitating the flexible movement and use of the slider 2. A mounting frame 6 is located directly above the guide frame 1, and multiple cylinders 7 are mounted on the mounting frame 6. The output ends of the cylinders 7 pass through the mounting frame 6 and are connected to the guide frame 1, used to drive the guide frame 1 to move up and down. The mounting frame 6 facilitates connection to a vehicle, allowing the entire testing device to be fixed to the vehicle. The cylinders 7 can drive the guide frame 1 to move up and down.

[0032] like Figure 2As shown, symmetrical grooves 11 are provided on both sides of the inside of the guide frame 1. The grooves 11 facilitate the engagement of the slider 2, allowing the slider 2 to move stably back and forth inside the guide frame 1. Connecting plates 12 are symmetrically provided on both sides of the top of the guide frame 1. Multiple connecting holes 13 are provided on the connecting plates 12. The engagement of the connecting plates 12 and the connecting holes 13 facilitates the connection between the output end of the cylinder 7 and the guide frame 1. First bearings 14 are provided in the middle of the front and rear end faces of the guide frame 1, facilitating a rotatable connection with the screw 4.

[0033] like Figure 3 As shown, rollers 22 are symmetrically arranged on both sides of the slider 2, and the rollers 22 are inserted into the slide groove 11; the rollers 22 facilitate the sliding connection between the slider 2 and the slide groove 11. A threaded hole 21 is provided in the middle of the slider 2, which facilitates the threaded connection between the slider 2 and the screw 4. Ear plates 23 are symmetrically arranged on both sides of the bottom surface of the slider 2, and a second bearing 24 is provided on each of the two ear plates 23. The ear plates 23 and the second bearings 24 facilitate the rotational connection between the slider 2 and the pressure roller 3.

[0034] like Figure 4 As shown, the pressure roller 3 integrates a pressure sensor and a displacement sensor. These sensors detect the applied pressure and monitor asphalt pavement deformation. During the compaction process, if the asphalt pavement deforms, the pressure sensed by the pressure sensor decreases, and the displacement sensor detects the displacement of the pressure roller 3, thus determining the amount of asphalt pavement deformation. Both ends of the pressure roller 3 have connecting shafts 31, which are interference-fitted with the second bearing 24. This structure facilitates the rotatable connection between the pressure roller 3 and the ear plate 23. The outer end of the connecting shaft 31 has a first connecting line 32, and the end of the first connecting line 32 has a first connecting plug 33. This structure facilitates the connection between the pressure roller 3 and the onboard data receiver, allowing for data feedback.

[0035] like Figure 5 As shown, both ends of the screw 4 are provided with adapter shafts 41, and the end of the screw 4 facing the motor 5 is provided with a drive slot 42; the adapter shaft 41 is for easy interference connection between the screw 4 and the first bearing 14, and the drive slot 42 is for easy connection between the output end of the motor 5 and the screw 4.

[0036] like Figure 6 As shown, the output end of motor 5 is equipped with a drive shaft 51, which is inserted into drive slot 42; this structure facilitates the rotation of screw 4 by motor 5. One end of motor 5 that is in contact with guide frame 1 is equipped with a fixing foot 52, which facilitates fixing the position of motor 5. A second connecting wire 53 is provided on the side of motor 5, and a second connecting plug 54 is provided at the end of the second connecting wire 53; the second connecting wire 53 and the second connecting plug 54 facilitate the connection of motor 5 to the control terminal.

[0037] like Figure 7As shown, a mounting plate 62 is provided on the inner side of the mounting frame 6, aligned with the position of the cylinder 7. A through hole 63 is provided in the middle of the mounting plate 62. The fit between the mounting plate 62 and the through hole 63 is to facilitate the passage of the output end of the cylinder 7 through the mounting plate 62. Multiple bolt holes 64 are provided at the rear end of the mounting frame 6. The bolt holes 64 are for easy fixing of the mounting frame 6 to the vehicle frame with bolts.

[0038] like Figure 8 As shown, the cylinder 7 has symmetrical mounting feet 71 on both sides of one end that is attached to the mounting plate 62. Each mounting foot 71 has multiple mounting holes 72. The fit between the mounting feet 71 and the mounting holes 72 facilitates fixing the position of the cylinder 7 with bolts. The output end of the cylinder 7 has a telescopic rod 73, and the bottom end of the telescopic rod 73 has a base 74 with multiple bottom holes 75. The base 74 is connected to the guide frame 1 with bolts. This structure facilitates the extension and retraction of the cylinder 7, which drives the guide frame 1 to move up and down.

[0039] Example 2

[0040] like Figure 1 As shown, an asphalt pavement deformation testing device includes a guide frame 1. A slider 2 is located inside the guide frame 1, and the slider 2 moves back and forth along the inside of the guide frame. The guide frame 1, in conjunction with the slider 2, facilitates the slider 2's movement back and forth within the guide frame 1. A pressure roller 3 is rotatably connected to the bottom end of the slider 2; the slider 2 drives the pressure roller 3 to move back and forth, thereby achieving the purpose of compacting the pavement. A screw 4 is located in the middle of the guide frame 1, and the screw 4 is threadedly connected to the slider 2. A motor 5 is located at the rear end of the guide frame 1, and the output end of the motor 5 is connected to the screw 4. This structure facilitates the rotation of the screw 4 by the motor 5, causing the screw 4 to drive the slider 2 to move back and forth along the inside of the guide frame 1, facilitating the flexible movement and use of the slider 2. A mounting frame 6 is located directly above the guide frame 1, and multiple cylinders 7 are mounted on the mounting frame 6. The output ends of the cylinders 7 pass through the mounting frame 6 and are connected to the guide frame 1, used to drive the guide frame 1 to move up and down. The mounting frame 6 facilitates connection to a vehicle, allowing the entire testing device to be fixed to the vehicle. The cylinders 7 can drive the guide frame 1 to move up and down.

[0041] like Figure 2 As shown, symmetrical grooves 11 are provided on both sides of the inside of the guide frame 1. The grooves 11 facilitate the engagement of the slider 2, allowing the slider 2 to move stably back and forth inside the guide frame 1. Connecting plates 12 are symmetrically provided on both sides of the top of the guide frame 1. Multiple connecting holes 13 are provided on the connecting plates 12. The engagement of the connecting plates 12 and the connecting holes 13 facilitates the connection between the output end of the cylinder 7 and the guide frame 1. First bearings 14 are provided in the middle of the front and rear end faces of the guide frame 1, facilitating a rotatable connection with the screw 4.

[0042] like Figure 3As shown, rollers 22 are symmetrically arranged on both sides of the slider 2, and the rollers 22 are inserted into the slide groove 11; the rollers 22 facilitate the sliding connection between the slider 2 and the slide groove 11. A threaded hole 21 is provided in the middle of the slider 2, which facilitates the threaded connection between the slider 2 and the screw 4. Ear plates 23 are symmetrically arranged on both sides of the bottom surface of the slider 2, and a second bearing 24 is provided on each of the two ear plates 23. The ear plates 23 and the second bearings 24 facilitate the rotational connection between the slider 2 and the pressure roller 3.

[0043] like Figure 4 As shown, the pressure roller 3 integrates a pressure sensor and a displacement sensor. These sensors detect the applied pressure and monitor asphalt pavement deformation. During the compaction process, if the asphalt pavement deforms, the pressure sensed by the pressure sensor decreases, and the displacement sensor detects the displacement of the pressure roller 3, thus determining the amount of asphalt pavement deformation. Both ends of the pressure roller 3 have connecting shafts 31, which are interference-fitted with the second bearing 24. This structure facilitates the rotatable connection between the pressure roller 3 and the ear plate 23. The outer end of the connecting shaft 31 has a first connecting line 32, and the end of the first connecting line 32 has a first connecting plug 33. This structure facilitates the connection between the pressure roller 3 and the onboard data receiver, allowing for data feedback.

[0044] like Figure 5 As shown, both ends of the screw 4 are provided with adapter shafts 41, and the end of the screw 4 facing the motor 5 is provided with a drive slot 42; the adapter shaft 41 is for easy interference connection between the screw 4 and the first bearing 14, and the drive slot 42 is for easy connection between the output end of the motor 5 and the screw 4.

[0045] like Figure 6 As shown, the output end of motor 5 is equipped with a drive shaft 51, which is inserted into drive slot 42; this structure facilitates the rotation of screw 4 by motor 5. One end of motor 5 that is in contact with guide frame 1 is equipped with a fixing foot 52, which facilitates fixing the position of motor 5. A second connecting wire 53 is provided on the side of motor 5, and a second connecting plug 54 is provided at the end of the second connecting wire 53; the second connecting wire 53 and the second connecting plug 54 facilitate the connection of motor 5 to the control terminal.

[0046] like Figure 7 As shown, a mounting plate 62 is provided on the inner side of the mounting frame 6, aligned with the position of the cylinder 7. A through hole 63 is provided in the middle of the mounting plate 62. The fit between the mounting plate 62 and the through hole 63 is to facilitate the passage of the output end of the cylinder 7 through the mounting plate 62. Multiple bolt holes 64 are provided at the rear end of the mounting frame 6. The bolt holes 64 are for easy fixing of the mounting frame 6 to the vehicle frame with bolts.

[0047] like Figure 8As shown, the cylinder 7 has symmetrical mounting feet 71 on both sides of one end that is attached to the mounting plate 62. Each mounting foot 71 has multiple mounting holes 72. The fit between the mounting feet 71 and the mounting holes 72 facilitates fixing the position of the cylinder 7 with bolts. The output end of the cylinder 7 has a telescopic rod 73, and the bottom end of the telescopic rod 73 has a base 74 with multiple bottom holes 75. The base 74 is connected to the guide frame 1 by bolts. This structure facilitates the extension and retraction of the cylinder 7, causing the guide frame 1 to move up and down.

[0048] like Figure 2 and Figure 7 As shown, guide rods 15 are provided at the top of both the front and rear ends of the guide frame 1. Guide holes 61 are provided at both the front and rear ends of the mounting frame 6, aligned with the guide rods 15. A limiting end plate 16 is provided at one end of the guide rod 15 that passes through the guide hole 61. This structure facilitates sufficient stability between the guide frame 1 and the mounting frame 6, allows the guide frame 1 to move up and down stably, and facilitates the adjustment and use of the guide frame 1.

[0049] Working principle: In use, the mounting frame 6 is installed on the vehicle frame, and then the guide frame 1 and its upper components are connected to the mounting frame 6. Next, the cylinder 7 is installed, causing the output end of the cylinder 7 and the guide frame 1 to move up and down. The cylinder 7 is then connected to the control device, and the pressure roller 3 and motor 5 are connected to the data receiving unit and control unit. When the detection point is reached, the cylinder 7 is activated, causing it to press down the guide frame 1, pressing the pressure roller 3 firmly onto the asphalt pavement. Then, the slider 2 of the motor 5 moves back and forth inside the guide frame 1. If the asphalt pavement deforms during the pressure application process, the pressure sensor will detect a decrease in pressure, while the displacement sensor will detect the displacement, thus determining the deformation of the asphalt pavement.

[0050] In summary, compared with the prior art, this application installs a slider 2 inside the guide frame 1, and a pressure roller 3 is set at the bottom of the slider 2. Then, the guide frame 1 is driven to move down by the cylinder 7, so that the pressure roller 3 is pressed tightly on the ground and a certain pressure is applied to the pressure roller 3. Then, the screw 4 is driven to rotate by the motor 5, so that the slider 2 and the pressure roller 3 move back and forth on the road surface to simulate the state of the wheel rolling the asphalt road surface. The pressure roller 3 integrates a displacement sensor and a pressure sensor. The deformation of the asphalt road surface can be determined by the pressure sensor and the data fed back by the pressure sensor.

[0051] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An asphalt deformation resistance testing device for asphalt pavement testing, comprising a guide frame (1), characterized in that, The guide frame (1) has a slider (2) inside, which moves back and forth along the inside of the guide block, and the bottom end of the slider (2) is rotatably connected to a pressure roller (3); the guide frame (1) has a screw (4) in the middle, which is threadedly connected to the slider (2); the guide frame (1) has a motor (5) at the rear end, and the output end of the motor (5) is connected to the screw (4); the guide frame (1) has a mounting frame (6) directly above it, and the mounting frame (6) has multiple cylinders (7), the output end of the cylinders (7) passes through the mounting frame (6) and is connected to the guide frame (1) to drive the guide frame (1) to move up and down.

2. The asphalt deformation resistance testing device for asphalt pavement testing according to claim 1, characterized in that, The guide frame (1) has symmetrical sliding grooves (11) on both sides inside, and the guide frame (1) has symmetrical connecting plates (12) on both sides of the top. The connecting plates (12) have multiple connecting holes (13), and the guide frame (1) has a first bearing (14) in the middle of the front and rear end faces.

3. The asphalt deformation resistance testing device for asphalt pavement testing according to claim 2, characterized in that, The slider (2) is symmetrically provided with rollers (22) on both sides, and the rollers (22) are inserted into the groove (11); the slider (2) is provided with a threaded hole (21) in the middle, and the slider (2) is provided with ear plates (23) symmetrically provided on both sides of the bottom surface, and each of the two ear plates (23) is provided with a second bearing (24).

4. The asphalt deformation resistance testing device for asphalt pavement testing according to claim 3, characterized in that, The pressure roller (3) integrates a pressure sensor and a displacement sensor, which are used to sense the applied pressure and detect the deformation of the asphalt pavement. Both ends of the pressure roller (3) are provided with connecting shafts (31), which are interference-fitted with the second bearing (24). The outer end of the connecting shaft (31) is provided with a first connecting line (32), and the end of the first connecting line (32) is provided with a first connecting plug (33).

5. The asphalt deformation resistance testing device for asphalt pavement testing according to claim 1, characterized in that, Both ends of the screw (4) are provided with adapter shafts (41), and the end of the screw (4) facing the motor (5) is provided with a drive slot (42).

6. The asphalt deformation resistance testing device for asphalt pavement testing according to claim 5, characterized in that, The motor (5) output end is provided with a drive shaft (51), which is inserted into the drive slot (42); the motor (5) is provided with a fixed foot (52) at one end that fits against the guide frame (1), and a second connecting line (53) is provided on the side of the motor (5), with a second connecting plug (54) at the end of the second connecting line (53).

7. The asphalt deformation resistance testing device for asphalt pavement testing according to claim 1, characterized in that, The mounting frame (6) has a mounting plate (62) aligned with the cylinder (7) on its inner side, and the mounting plate (62) has a through hole (63) in the middle; the mounting frame (6) has multiple bolt holes (64) at its rear end.

8. The asphalt deformation resistance testing device for asphalt pavement testing according to claim 7, characterized in that, The cylinder (7) has mounting feet (71) symmetrically arranged on both sides of one end of the mounting plate (62), and the mounting feet (71) have multiple mounting holes (72); the cylinder (7) has a telescopic rod (73) at the output end, and the bottom end of the telescopic rod (73) has a foot (74), and the foot (74) has multiple bottom holes (75). The foot (74) is connected to the guide frame (1) by bolts.

9. An asphalt deformation resistance testing device for asphalt pavement testing according to any one of claims 1-8, characterized in that, The guide frame (1) has guide rods (15) at both the front and rear ends. The mounting frame (6) has guide holes (61) at both the front and rear ends aligned with the guide rods (15). The end of the guide rod (15) that passes through the guide hole (61) is provided with a limiting end plate (16).

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