A surveying and mapping device for field investigation based on national land space planning

Abstract

The present invention relates to the technical field of surveying and mapping supports, and in particular to a surveying and mapping device for field investigation based on national land space planning, comprising a stand, the lower surface of which is rotatably connected with three support legs, the upper surface of which is fixedly mounted with a surveying instrument, a slider is slidably inserted into the lower port of the support leg, an hourglass-shaped groove is provided on the inner side of the slider, a swing rod is rotatably penetrated on the inner side of the hourglass-shaped groove, a corner block is fixedly connected to the lower end of the swing rod, a groove is provided on the upper end surface of the swing rod, and a moving handle is movably connected to the inner side of the groove through an elastic mechanism. The present invention allows the corner block that swings back and forth to push away the grass layer to ensure that it can be inserted into the ground, and the grass layer will not be pressed after insertion, which can effectively avoid the problem of unstable arrangement caused by the grass layer bouncing up, and also has a protective function to prevent the sharp corner block from stabbing the user.

Description

Technical Field

[0001] The present invention relates to the technical field of surveying and mapping brackets, and in particular to a surveying and mapping device used for field investigation based on national land space planning. Background Art

[0002] The main purpose of the field investigation of national land space planning is to fully understand and evaluate the current status, implementation effect and existing problems of the national land space planning in the planning area. Through field investigation, first-hand information can be obtained to provide a scientific basis for planning preparation, approval and management, and it also helps to promote the implementation and supervision of the plan. National land planning surveying and mapping is a comprehensive work, which involves the measurement, measurement and mapping of national land space, aiming to obtain information about the geometry, shape, location, size, distribution and attributes of the earth's surface and its appendages. During the surveying and mapping process, the ground conditions of the surveying and mapping points are relatively complex.

[0003] It is inconvenient to arrange the tripod and the surveying instrument on the ground with thick grass layer. Due to the thick grass layer, the root and stem of the grass in the grass layer are easily inserted into the ground during the insertion of the bottom of the tripod into the ground. Afterwards, the root and stem have a tendency to recover, which will cause the bottom of the tripod to be raised, resulting in unstable arrangement and easy tilting, which in turn affects the normal operation of the surveying instrument and greatly reduces the surveying accuracy.

[0004] In addition, the tripod of the surveying instrument is sharpened at the lower end to ensure that it remains stable when inserted into the ground, which can easily cause accidental injury during transportation, especially when transporting and moving in the field, as the user may easily stand unsteadily and the exposed sharp parts can easily cause danger. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings existing in the background technology and to propose a surveying and mapping device for field investigation based on national land space planning.

[0006] The cam is provided with a plurality of support legs, the support legs are provided with a plurality of support legs, the support legs are provided with a plurality of support legs, and the support legs are provided with a plurality of support legs. The pedal is pressed by the foot, and the moving handle moves outward and rotates downward relative to the swing rod, so that the abutment mechanism no longer contacts the bracket leg; After the arc frame slides up relative to the pedal, the foot is prevented from falling off when pressing on the upper surface of the pedal; After the arc frame slides down relative to the pedal board, the lower end of the corner block is located at the inner side of the arc frame.

[0007] Preferably, the upper end of the bracket leg is fixedly connected to the rotating block, and the upper end of the rotating block is rotatably embedded in the lower surface of the frame seat, and the frame seat has a connecting bolt that rotates through the side surface of each rotating block, one end of the connecting bolt is threadedly sleeved with a connecting nut, and the connecting bolt is fixed through the inner side of the rotating block.

[0008] Preferably, two side surfaces of the swing rod and the inner sides corresponding to the hourglass-shaped groove are respectively fixedly connected with rotation shafts, and the rotation shafts are rotatably embedded in the inner wall of the hourglass-shaped groove.

[0009] Preferably, the elastic mechanism includes a sliding shaft fixedly connected to one end of the movable handle, side grooves are respectively opened on both side walls of the groove, both ends of the sliding shaft are respectively slidably inserted into the inner side of the side groove, a limiting block is slidably inserted into the inner side of the side groove, the limiting block is in sliding contact with the surface of the sliding shaft, a compression spring is fixedly connected to a side of the limiting block away from the limiting block, and one end of the compression spring is fixed to the inner wall of the side groove.

[0010] Preferably, the locking mechanism includes two guide grooves opened on the edge of the pedal, and a pull plate is provided at the end of the pedal through a pulling mechanism. Two insertion rods are fixedly connected to the one side surface of the pull plate, and the insertion rods slide through the pedal and extend to the inner side of the guide groove. The two sides of the arc frame slide through the inner side of the guide groove respectively, and limiting holes are respectively provided on the outer surface of the arc frame near the upper and lower ends, and each of the insertion rods is slidably inserted into the inner side of one of the limiting holes.

[0011] Preferably, the pulling mechanism includes a fixed cylinder fixedly connected to the lower surface of the pedal, a sliding column is slidably inserted into one side of the fixed cylinder, one end of the sliding column is fixedly connected to the surface of the shift plate, and the other end of the sliding column is fixedly connected to a limiting plate, the limiting plate is in sliding contact with the inner wall of the fixed cylinder, and a return spring is sleeved on the outer surface of the sliding column, and the return spring is located on the inner side of the fixed cylinder.

[0012] Preferably, a trapezoidal bayonet is provided at the upper end of the arc-shaped frame, the trapezoidal bayonet is sleeved on the outer surface of the bracket leg, and smooth portions are respectively provided at the two lower ends of the arc-shaped frame.

[0013] Preferably, the abutment mechanism includes an L-shaped block arranged at the end of the protrusion, a T-shaped column is fixedly connected to the inner side of the L-shaped block, the T-shaped column slides through the side surface of the protrusion, a pressure spring is sleeved on the outer surface of the T-shaped column, and the pressure spring is located between the inner wall of the L-shaped block and the side surface of the protrusion, the L-shaped block is provided with an inclined guide surface near the corner of the bracket leg, a friction plate is fixedly connected to the corner of the outer surface of the bracket leg, and one side of the L-shaped block is in contact with the friction plate.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. In the invention, the user's feet move back and forth to step on the pedal to drive the swing rod to swing back and forth around the rotation axis. The swinging corner block pushes the grass layer away to ensure that it can be inserted into the ground, and the grass layer will not be pressed after insertion, which can effectively avoid the problem of unstable layout caused by the grass layer bouncing up; 2. After the corner block is pressed down and inserted into the ground, the foot is released and then lifted up to hook up the arc frame to move the pedal upward. Under the action of the compression spring, the limit block pushes the sliding shaft to reset and move. Under the guidance of the inclined guide surface, the L-shaped blocks on both sides are smoothly clamped on the two sides of the bracket leg. With the action of the friction plate and the elastic force of the pressure spring, a large friction force is generated between the friction plate and the L-shaped block to ensure that the pedal is stably limited, that is, the corner block, the swing rod and other structures are positioned to form a stable support on the ground; at the same time, during the lifting process, the trapezoidal bayonet will be correspondingly sleeved on the surface of the bracket leg, further improving the stability of the pedal. The positioning can be completed by lifting the pedal, thereby maintaining the stability of the corner block and convenient operation. 3. When the present invention is folded up for transportation, the dial plate is pulled to make the insertion rod disengage from the inner side of the limiting hole, and then the arc frame is pressed down so that the lower end of the arc frame is sleeved on the outer periphery of the lower end of the corner block to play a protective role. Then, the user lets go and, under the action of the reset spring, the limit plate is pushed to reset the sliding column. After the insertion rod is inserted into another limiting hole, the arc frame is kept stably positioned. Therefore, the arc frame has a protective function to prevent the sharp corner block from injuring the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of a surveying and mapping device for field investigation based on national land space planning according to the present invention; Figure 2 The present invention is a surveying and mapping device for field investigation based on national land space planning Figure 1 Enlarged view of point A in the middle; Figure 3 This is a schematic diagram of the lower end of the support leg of a surveying and mapping device for field investigation based on national land space planning according to the present invention; Figure 4 A partial cross-sectional view of a support leg of a surveying and mapping device for field investigation based on national land space planning according to the present invention; Figure 5 The present invention is a surveying and mapping device for field investigation based on national land space planning Figure 4 Enlarged view of point B in the middle; Figure 6 A cross-sectional view of a slider of a surveying and mapping device for field investigation based on national land space planning according to the present invention; Figure 7 The present invention is a surveying and mapping device for field investigation based on national land space planning Figure 6 Enlarged view of point C in the middle; Figure 8 It is a schematic diagram of the sliding opening of a surveying and mapping device for field investigation based on national land space planning according to the present invention; Fig. 9 A schematic diagram of a pedal position of a surveying and mapping device for field investigation based on national land space planning according to the present invention; Fig.10 A diagram showing the state of the supporting legs of a surveying and mapping device for field investigation based on national land space planning according to the present invention when the device is stored; Fig.11 This is a state diagram of the supporting leg of a surveying and mapping device used for field investigation in national land space planning when stepping on it.

[0016] 1. Bracket leg; 2. Bracket seat; 3. Surveying instrument; 4. Rotating block; 5. Connecting bolt; 6. Connecting nut; 7. Sliding block; 8. Hourglass groove; 9. Swinging rod; 10. Rotating shaft; 11. Groove; 12. Moving handle; 13. Sliding shaft; 14. Side groove; 15. Limiting block; 16. Compression spring; 17. Stepping pedal; 18. Arc bracket; 19. Trapezoidal bayonet; 20. Limiting hole; 21. Smooth part; 22. Guide groove; 23. Insert rod; 24. Paddle plate; 25. Fixed cylinder; 26. Sliding column; 27. Reset spring; 28. Limiting plate; 29. ​​Bump; 30. L-shaped block; 31. Oblique guide surface; 32. T-shaped column; 33. Pressure spring; 34. Sliding mouth; 35. Corner block; 36. Friction plate. DETAILED DESCRIPTION

[0017] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0018] like Figure 1-Figure 11The surveying and mapping device shown in the figure for field investigation based on national land space planning comprises a frame 2, the lower surface of the frame 2 is rotatably connected with three frame legs 1, the upper surface of the frame 2 is fixedly installed with a surveying instrument 3, a slider 7 is slidably inserted into the lower port of the frame leg 1, an hourglass-shaped groove 8 is provided on the inner side of the slider 7, a swing rod 9 is rotatably penetrated on the inner side of the hourglass-shaped groove 8, a corner block 35 is fixedly connected to the lower end of the swing rod 9, a groove 11 is provided on the upper end surface of the swing rod 9, a moving handle 12 is movably connected to the inner side of the groove 11 through an elastic mechanism, a sliding opening 34 is respectively provided on the side of the three frame legs 1 away from each other and near the lower end, the moving handle 12 passes through the sliding opening 34 and is fixedly connected with a pedal 17, an arc frame 18 is inserted on the edge of the pedal 17 through a locking mechanism, two corners of the pedal 17 close to the frame leg 1 are respectively extended with protrusions 29, and the two protrusions 29 are respectively provided with abutment mechanisms contacting the surface of the frame leg 1 on the side close to each other; The length design of the moving handle 12 needs to meet the following conditions: when the pedal 17 is pressed by the user's foot, the moving handle 12 moves outward and rotates downward relative to the swing rod 9, and then the abutment mechanism no longer contacts the bracket leg 1; After the arc frame 18 slides up relative to the pedal 17, the state is as follows Figure 3 As shown, at this time, when the user's foot presses on the upper surface of the pedal 17, it can prevent the pedal from falling off; When the arc frame 18 slides down relative to the pedal 17, the lower end of the corner block 35 is located inside the arc frame 18, and the state is as follows: Fig.10 As shown, at this time, the lower end of the corner block 35 is protected to prevent the user from being stabbed.

[0019] like Figure 1 , Figure 2 As shown, the upper end of the support leg 1 is fixedly connected to the rotating block 4, and the upper end of the rotating block 4 is rotatably embedded in the lower surface of the frame 2. The frame 2 is rotatably penetrated by a connecting bolt 5 at the side surface corresponding to each rotating block 4. A connecting nut 6 is threadedly sleeved on one end of the connecting bolt 5, and the connecting bolt 5 is fixedly passed through the inner side of the rotating block 4. By loosening the connecting nut 6, the support leg 1 can be rotated relative to the frame 2, and by tightening the connecting nut 6, the stability of the support leg 1 can be ensured. The three support legs 1 can be adjusted separately according to the inclination of the ground to ensure that the surveying instrument 3 remains level.

[0020] like Figure 6 As shown, the two side surfaces of the swing rod 9 and the inner sides of the hourglass-shaped groove 8 are respectively fixedly connected with a rotating shaft 10, and the rotating shaft 10 is rotatably embedded in the inner wall of the hourglass-shaped groove 8. The design of the hourglass-shaped groove 8 can limit the swing amplitude of the swing rod 9.

[0021] like Figure 4 , Figure 5 , Figure 6 , Figure 7As shown, the elastic mechanism includes a sliding shaft 13 fixedly connected to one end of the moving handle 12, and side grooves 14 are respectively provided on the two side walls of the groove 11. The two ends of the sliding shaft 13 are respectively slidably inserted into the inner side of the side groove 14, and a limiting block 15 is slidably inserted into the inner side of the side groove 14. The limiting block 15 is in sliding contact with the surface of the sliding shaft 13, and a compression spring 16 is fixedly connected to the side of the limiting block 15 away from the limiting block 15, and one end of the compression spring 16 is fixed to the inner wall of the side groove 14. This part of the design allows the moving handle 12 to move and rotate relative to the upper end of the swing rod 9. Obviously, the inner side height of the groove 11 should not be too high, which can prevent the moving handle 12 from rotating downward at too large an angle, thereby causing the edge of the pedal 17 to hit the bracket leg 1.

[0022] like Fig. 9 , Fig.10 As shown, the locking mechanism includes two guide grooves 22 opened at the edge of the pedal 17, and a pull plate 24 is provided at the end of the pedal 17 through a pulling mechanism. Two insertion rods 23 are fixedly connected to one side surface of the pull plate 24. The insertion rods 23 slide through the pedal 17 and extend to the inner side of the guide groove 22. The two sides of the arc frame 18 slide through the inner side of the guide groove 22 respectively. The outer surface of the arc frame 18 and near the upper and lower ends are respectively provided with limited holes 20, and each insertion rod 23 slides into the inner side of one of the limited holes 20. The positioning of the arc frame 18 at two positions is realized.

[0023] The pulling mechanism includes a fixed cylinder 25 fixedly connected to the lower surface of the pedal 17, a sliding column 26 is slidably inserted into one side of the fixed cylinder 25, one end of the sliding column 26 is fixedly connected to the surface of the dial plate 24, and the other end of the sliding column 26 is fixedly connected to a limit plate 28, the limit plate 28 is in sliding contact with the inner wall of the fixed cylinder 25, and a return spring 27 is sleeved on the outer surface of the sliding column 26, and the return spring 27 is located on the inner side of the fixed cylinder 25. When the dial plate 24 is pulled, the return spring 27 will be squeezed, and after letting go, the insertion rod 23 and the dial plate 24 will move and reset under the elastic force of the return spring 27.

[0024] like Fig.10 As shown, the upper end of the arc frame 18 is provided with a trapezoidal bayonet 19, which is sleeved on the outer surface of the bracket leg 1, and the two lower ends of the arc frame 18 are respectively provided with smooth portions 21, which play a protective role and prevent the sharp ends from being scratched. The design of the trapezoidal bayonet 19 makes it smoother to be clamped on the surface of the bracket leg 1, avoiding the problem of difficulty in clamping.

[0025] like Figure 5 , Figure 6As shown, the abutment mechanism includes an L-shaped block 30 disposed at the end of the protrusion 29, a T-shaped column 32 is fixedly connected to the inner side of the L-shaped block 30, the T-shaped column 32 slides through the side surface of the protrusion 29, a compression spring 33 is sleeved on the outer surface of the T-shaped column 32, and the compression spring 33 is located between the inner wall of the L-shaped block 30 and the side surface of the protrusion 29, and an inclined guide surface 31 is provided at the corner of the L-shaped block 30 near the bracket leg 1, and a friction plate 36 is fixedly connected to the corner of the outer surface of the bracket leg 1, and one side of the L-shaped block 30 is in contact with the friction plate 36. The size design of the L-shaped block 30 needs to meet the following requirements: after the pedal 17 is pressed by the foot, the moving handle 12 moves outward and rotates downward relative to the swing rod 9, and the L-shaped block 30 will not contact the surface of the bracket leg 1.

[0026] During use, the three bracket legs 1 are rotated to a suitable angle relative to the bracket base 2 and then placed on the ground. Then, holding one of the bracket legs 1, the user bends slightly and presses the foot on the surface of the pedal 17. The pedal 17 is pressed by the foot, and the moving handle 12 moves outward and rotates downward relative to the swing rod 9. During this process, the sliding shaft 13 slides relatively along the inner side of the side groove 14, pushing the limiting block 15 and squeezing the compression spring 16. At the same time, the sliding shaft 13 also rotates relatively in the side groove 14 to ensure that the outward movement and downward rotation of the moving handle 12 will not be interfered with. Subsequently, the L-shaped block 30 is separated from the bracket leg 1, and the trapezoidal bayonet 19 at the upper end of the arc frame 18 is also synchronously separated from the bracket leg 1. At this time, the state is as follows: Fig.11 As shown, the user's feet move back and forth, so that the pedal 17 drives the swing rod 9 to swing back and forth around the rotating shaft 10. The swinging corner block 35 pushes the grass layer aside to ensure that it can be inserted into the ground, and the grass layer will not be pressed after insertion, which can effectively avoid the problem of unstable layout caused by the grass layer bouncing up.

[0027] When the corner block 35 is pressed down and inserted into the ground, the foot is released and then lifted up to hook the arc frame 18 and move the pedal board 17 upward. Under the action of the compression spring 16, the limit block 15 pushes the sliding shaft 13 to reset and move. Under the guidance of the inclined guide surface 31, the L-shaped blocks 30 on both sides are smoothly clamped on the two sides of the bracket leg 1. With the action of the friction plate 36 and the elastic force of the pressure spring 33, a large friction force is generated between the friction plate 36 and the L-shaped block 30, ensuring that the pedal board 17 is stably limited, that is, the corner block 35, the swing rod 9 and other structures are positioned to form a stable support on the ground; at the same time, during the lifting process, the trapezoidal bayonet 19 will be correspondingly sleeved on the surface of the bracket leg 1, further improving the stability of the pedal board 17.

[0028] When the whole is folded up for transportation, the lever 24 is pulled to make the rod 23 disengage from the inner side of the limiting hole 20, and the arc frame 18 is pressed down so that the lower end of the arc frame 18 is sleeved on the outer periphery of the lower end of the corner block 35 to play a protective role. Then, the lever 24 is released, and the limiting plate 28 is pushed under the action of the reset spring 27 to reset the sliding column 26. After the rod 23 is inserted into another limiting hole 20, the stable positioning of the arc frame 18 is maintained. Fig.10 As shown, therefore, it has a protective function to prevent the sharp corner block 35 from stabbing the user.

[0029] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A surveying and mapping device for field investigation based on national land space planning, comprising a stand (2), wherein the lower surface of the stand (2) is rotatably connected to three support legs (1), characterized in that: A surveying instrument (3) is fixedly mounted on the upper surface of the frame seat (2); a slider (7) is slidably inserted into the lower end of the support leg (1); an hourglass-shaped groove (8) is provided on the inner side of the slider (7); a swing rod (9) is rotatably penetrated through the inner side of the hourglass-shaped groove (8); a corner block (35) is fixedly connected to the lower end of the swing rod (9); a groove (11) is provided on the upper end surface of the swing rod (9); a moving handle (12) is movably connected to the inner side of the groove (11) via an elastic mechanism; A sliding opening (34) is respectively provided on one side of the three support legs (1) away from each other and near the lower end; the movable handle (12) passes through the sliding opening (34) and is fixedly connected to a pedal (17); an arc frame (18) is inserted into the edge of the pedal (17) through a locking mechanism; two corners of the pedal (17) near the support legs (1) are respectively extended with protrusions (29); and abutment mechanisms for contacting the surface of the support legs (1) are respectively provided on one side of the two protrusions (29) near each other; The pedal (17) is pressed by the foot, so that the movable handle (12) moves outward and rotates downward relative to the swing rod (9), and the abutment mechanism no longer contacts the bracket leg (1); After the arc-shaped frame (18) slides upward relative to the pedal (17), the foot is pressed against the upper surface of the pedal (17) to prevent it from falling off; After the arc-shaped frame (18) slides down relative to the pedal (17), the lower end of the corner block (35) is located on the inner side of the arc-shaped frame (18).

2. A surveying and mapping device for field investigation based on national land space planning according to claim 1, characterized in that: The upper end of the support leg (1) is fixedly connected to the rotating block (4), and the upper end of the rotating block (4) is rotatably embedded in the lower surface of the frame seat (2). The frame seat (2) has a connecting bolt (5) rotatably penetrated at the side surface corresponding to each rotating block (4), and one end of the connecting bolt (5) is threadedly sleeved with a connecting nut (6), and the connecting bolt (5) is fixedly passed through the inner side of the rotating block (4).

3. A surveying and mapping device for field investigation based on national land space planning according to claim 1, characterized in that: Rotating shafts (10) are respectively fixedly connected to the two side surfaces of the swing rod (9) and the inner sides of the corresponding hourglass-shaped grooves (8), and the rotating shafts (10) are rotatably embedded in the inner wall of the hourglass-shaped grooves (8).

4. The surveying and mapping device for field investigation based on national land space planning according to claim 1, characterized in that: The elastic mechanism comprises a sliding shaft (13) fixedly connected to one end of the moving handle (12); side grooves (14) are respectively provided on the two side walls of the groove (11); the two ends of the sliding shaft (13) are respectively slidably inserted into the inner sides of the side grooves (14); a limiting block (15) is slidably inserted into the inner sides of the side grooves (14); the limiting block (15) is in sliding contact with the surface of the sliding shaft (13); a compression spring (16) is fixedly connected to a side of the limiting block (15) away from the limiting block (15); and one end of the compression spring (16) is fixed to the inner wall of the side groove (14).

5. The surveying and mapping device for field investigation based on national land space planning according to claim 1, characterized in that: The locking mechanism comprises two guide grooves (22) formed at the edge of the pedal (17); a shift plate (24) is provided at the end of the pedal (17) via a pulling mechanism; two insertion rods (23) are fixedly connected to a surface of one side of the shift plate (24); the insertion rods (23) slide through the pedal (17) and extend to the inner side of the guide groove (22); the two sides of the arc frame (18) slide through the inner side of the guide groove (22); the outer surface of the arc frame (18) and near the upper and lower ends are respectively provided with limiting holes (20); each of the insertion rods (23) slides and is inserted into the inner side of one of the limiting holes (20).

6. The surveying and mapping device for field investigation based on national land space planning according to claim 5, characterized in that: The pulling mechanism comprises a fixed cylinder (25) fixedly connected to the lower surface of the pedal (17), a sliding column (26) is slidably inserted into one side of the fixed cylinder (25), one end of the sliding column (26) is fixedly connected to the surface of the shift plate (24), and the other end of the sliding column (26) is fixedly connected to a limit plate (28), the limit plate (28) is in sliding contact with the inner wall of the fixed cylinder (25), and a return spring (27) is sleeved on the outer surface of the sliding column (26), and the return spring (27) is located on the inner side of the fixed cylinder (25).

7. The surveying and mapping device for field investigation based on national land space planning according to claim 1, characterized in that: The upper end of the arc frame (18) is provided with a trapezoidal bayonet (19), the trapezoidal bayonet (19) is sleeved on the outer surface of the bracket leg (1), and smooth portions (21) are respectively provided at the two lower ends of the arc frame (18).

8. The surveying and mapping device for field investigation based on national land space planning according to claim 1, characterized in that: The abutting mechanism comprises an L-shaped block (30) arranged at the end of the protrusion (29); a T-shaped column (32) is fixedly connected to the inner side of the L-shaped block (30); the T-shaped column (32) slides through the side surface of the protrusion (29); a pressure spring (33) is sleeved on the outer surface of the T-shaped column (32); and the pressure spring (33) is located between the inner wall of the L-shaped block (30) and the side surface of the protrusion (29); an inclined guide surface (31) is provided at a corner of the L-shaped block (30) close to the bracket leg (1); a friction plate (36) is fixedly connected to the corner of the outer surface of the bracket leg (1); and one side of the L-shaped block (30) is in contact with the friction plate (36).

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