CN114634057B

CN114634057B - Auxiliary device for laying electric power transmission line

Info

Publication number: CN114634057B
Application number: CN202210318355.XA
Authority: CN
Inventors: 赵倩; 冯孟召; 王飞; 刘辉; 史佳音
Original assignee: State Grid Henan Electric Power Co Luanchuan County Power Supply Co; State Grid Corp of China SGCC
Current assignee: State Grid Henan Electric Power Co Luanchuan County Power Supply Co; State Grid Corp of China SGCC
Priority date: 2022-03-29
Filing date: 2022-03-29
Publication date: 2023-07-04
Anticipated expiration: 2042-03-29
Also published as: CN114634057A

Abstract

The invention discloses an auxiliary device for laying an electric power transmission line, wherein a vertically placed cable drum is placed in an annular groove on a base, a driving mechanism for driving the cable drum to rotate is arranged at the upper part of the base, a vertical rod matched with the vertically placed cable drum is arranged at one side of the upper surface of the base, a cable carding mechanism capable of sliding along the axial direction of the vertical rod is arranged on a rod body of the vertical rod, and the cable carding mechanism clamps a conveying cable in the rotation process of winding or unwinding the cable drum and drives the conveying cable to reciprocate up and down through a lifting adjusting mechanism so as to realize cable carding operation on the cable drum; according to the invention, the cable tray can be stably and conveniently vertically placed in the annular groove at the upper part of the base through the lifting device, and the cable tray is driven by the driving mechanism to rotate so as to realize the winding and unwinding operation of the cable, and the cable carding mechanism can realize the reasonable and orderly winding or conveying operation of the cable, so that the phenomenon of winding and knotting of the cable on the cable tray is effectively avoided.

Description

Auxiliary device for laying electric power transmission line

Technical Field

The invention relates to the technical field of cable laying, in particular to an auxiliary device for laying an electric power transmission line.

Background

The cable is a generic name of articles such as optical cables, cables and the like, has a plurality of purposes, is mainly used for controlling multiple functions such as installation, connection equipment, power transmission and the like, is a common and indispensable article in daily life, and along with the development of society, in order to ensure normal power supply requirements of people, the power utilization requirements of people are met through laying a large number of cables.

At present, in the process of laying a power line, a cable needs to be rolled or conveyed, the existing mode is to wind the cable on a cable drum for transportation, and then the cable drum is erected on a cable frame for rotation, so that the rolling or conveying operation of the cable at the later stage is convenient, and the following defects exist in the current cable rolling and conveying process:

1. in order to ensure the safety of cable transportation, the cable reel is often vertically placed in the transportation process, when the cable reel is lifted to the ground by follow-up lifting equipment, the cable reel is lifted vertically and placed on the ground in order to ensure the stability of lifting, and the cable reel is required to be manually moved by staff subsequently, so that the cable reel for winding a cable with a large diameter has large weight, and the manual movement is time-consuming and labor-consuming;

2. the existing cable tray support is used for horizontally supporting the cable tray to rotate, and workers are required to carry the cable tray during erection operation, so that the operation difficulty of the workers is greatly increased;

3. when the winding or paying-off operation of the cable is performed, in order to avoid the cable winding phenomenon on the cable drum, the cable needs to be conveyed in a spiral lifting reciprocating mode all the time, however, in the winding and conveying process of the outdoor cable, manual control can be performed only, and for large-diameter cables, the manual control of orderly winding or conveying of the cable on the cable drum is difficult to perform accurately;

therefore, there is an urgent need for a device capable of conveniently and efficiently conveying cables outdoors, which provides support for subsequent cable laying.

Disclosure of Invention

In order to overcome the defects in the background art, the invention discloses an auxiliary device for laying an electric power transmission line, which can stably and conveniently vertically place a cable tray in an annular groove at the upper part of a base through lifting equipment, and drive the cable tray to rotate through a driving mechanism so as to realize the wire winding and unwinding operation of the cable.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the utility model provides an auxiliary device for electric power transmission line lays, including base and cable dish, base upper portion face is equipped with the ring channel, bottom surface evenly distributed has the several to be used for supporting the cable dish in the ring channel, and realize cable dish pivoted rolling element, the cable dish of vertical placing is placed in the ring channel on the base, base upper portion is equipped with the actuating mechanism that drives the cable dish and carries out the rotation, base upper portion face one side is equipped with the montant with the cable dish looks adaptation of vertical placing, be equipped with on the body of rod of montant and carry out gliding cable carding mechanism along montant axial, montant one side is equipped with the lift adjustment mechanism that drives the cable carding mechanism and carries out the lift gliding along the montant axial, the cable dish is in the rotation in-process of receipts line or unwrapping wire, cable carding mechanism centre gripping transfer cable, and carry out reciprocal elevating movement through lift adjustment mechanism drive it, realize the cable carding operation on the cable dish.

Further, the middle part of the vertically placed cable drum forms a columnar inner cavity, the upper end and the lower end of the columnar inner cavity are of an open structure, and the driving mechanism is arranged in the middle of the annular groove and is positioned in the columnar inner cavity.

Further, actuating mechanism includes servo motor and actuating lever, and column inner chamber lower part inner wall both sides are equipped with corresponding draw-in groove, and the draw-in groove lower extreme is open structure, and the ring channel middle part is equipped with servo motor, servo motor's output fixedly connected with actuating lever, in the open slip corresponding draw-in groove of draw-in groove lower extreme was passed through at the both ends of actuating lever, and rotates through servo motor's drive belt cable tray.

Further, a lifting frame is arranged on the upper portion of the columnar inner cavity, and a detachable lifting hook is arranged on the upper portion of the lifting frame.

Further, the bottom surface is equipped with the bottom annular in the ring channel, and the cross section of bottom annular is the type structure of falling T, is equipped with in the bottom annular and carries out gliding bolt along the bottom annular, is equipped with the spacing hole with bolt looks adaptation on the cable dish bottom curb plate of vertical placing, and the head of bolt runs through spacing hole and passes through the nut and fix.

Further, the cable carding mechanism comprises a movable block, an upper pressing roller and a conveying roller, a through hole penetrating through the movable block and being matched with the vertical rod is formed in the movable block, a conveying cable is clamped on one side of the movable block, and the clamping distance of the conveying cable can be adjusted through the upper pressing roller and the conveying roller.

Further, the lifting adjusting mechanism comprises a screw rod and a driving motor, the screw rod parallel to the vertical rod is arranged on one side of the vertical rod, the driving motor for driving the screw rod to rotate is arranged on the lower portion of the screw rod, and a screw hole which penetrates through the movable block and is matched with the screw rod in a threaded mode is formed in the movable block.

Further, the upper end of the vertical rod is provided with a top plate, the upper end of the screw rod is rotationally connected with the lower surface of the top plate, and the lower surface of the top plate and the upper surface of the base are respectively provided with a limit switch for touching the induction movable block and controlling the driving motor to reversely rotate.

Further, go up the compression roller and include horizontal pole, fixed roller, movable roller and belleville nut, fixed roller and movable roller are toper structure, and the one end and the slider fixed connection of horizontal pole, the body of rod inner rotation of horizontal pole are connected with the fixed roller, and the body of rod outer end rotation of horizontal pole is connected with can follow the gliding movable roller of body of rod axial, and the fixed roller sets up relatively with the tip of movable roller, is equipped with the screw thread on the body of rod of horizontal pole, and the horizontal pole outer end is equipped with the belleville nut that is used for adjusting interval between movable roller and the fixed roller.

Further, the outer end of the conveying roller is provided with a cable length calculating mechanism for calculating and displaying the cable conveying length by recording the rotation number of the conveying roller.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, the cable tray can be stably and conveniently vertically placed in the annular groove at the upper part of the base through the lifting device, and the cable tray is driven by the driving mechanism to rotate so as to realize the wire winding and paying-off operation of the cable, and in the wire winding and paying-off process, the cable carding mechanism can be used for realizing the reasonable and orderly winding or conveying operation of the cable, so that the phenomenon of winding and knotting of the cable on the cable tray is effectively avoided, and great convenience is provided for the laying of the cable;

the invention adopts a mode of vertically placing the cable tray, avoids the mode that the traditional cable rack needs to rotate the cable tray rack, not only provides convenience for lifting the cable tray by the lifting equipment, but also does not need subsequent staff to manually move the cable tray for erection operation;

by arranging the driving mechanism in the columnar inner cavity, when the cable drum is lifted and placed, the driving connection between the driving mechanism and the cable drum can be directly completed, so that the working difficulty of workers is greatly reduced, and the stable and effective rotation of the cable drum is ensured;

by arranging the lifting frame, great convenience is provided for the lifting of the cable tray, and the stability of the cable tray in the lifting process is effectively ensured;

by arranging the bottom ring groove and the bolts, the limit protection of the cable tray can be realized, the cable tray is prevented from being separated from the ring groove in the rotation process, and the rotation stability of the cable tray is ensured;

through the cable carding mechanism capable of lifting and sliding, when the cable is rolled or paid off, the cable carding mechanism can drive the cable to lift and adjust, the cable can be uniformly and effectively wound on the cable drum in the cable rolling process, the cable can be effectively prevented from being pressed, and the cable can be stably and effectively conveyed in the cable conveying process, so that the cable on the cable drum is prevented from loosening and falling;

when the cable carding mechanism ascends or descends to the maximum value, the limit switches are touched to send out control instructions, so that the driving motor is reversed, and the up-and-down reciprocating motion of the cable carding mechanism is realized;

the upper press roller can be matched with the conveying roller to realize effective conveying of the cable, and the diameter of the cable can be adaptively adjusted;

the winding or conveying length of the cable can be displayed in real time according to the rotation number of the conveying roller through the cable length calculating mechanism, so that accurate and effective conveying of the cable is realized;

according to the invention, the cable drum which is vertically placed is driven to rotate, and is matched with the conveying of the cable carding mechanism, so that great convenience is provided for lifting and installing the cable drum, the manual operation difficulty of workers is greatly reduced, powerful support is provided for reasonably and effectively winding or conveying the cable, the situations of uneven winding, line pressing, loosening and falling and the like of the cable on the cable drum are effectively avoided, and powerful assistance is provided for conveying the cable in the subsequent cable laying process.

Drawings

FIG. 1 is a schematic diagram of the structure of the present invention;

FIG. 2 is a schematic view of a base structure of the present invention;

FIG. 3 is a schematic view of a cable tray according to the present invention;

FIG. 4 is a schematic view of a lifting adjusting mechanism according to the present invention;

FIG. 5 is a schematic view of a cable carding mechanism of the present invention;

fig. 6 is a schematic view of the structure of the upper press roll of the present invention.

In the figure: 1. a lifting hook; 2. a lifting frame; 3. a cable drum; 4. a vertical rod; 5. a cable carding mechanism; 6. a driving mechanism; 7. a base; 8. a driving rod; 9. a servo motor; 10. a screw cap; 11. a bolt; 12. an annular groove; 13. a rolling member; 14. a bottom ring groove; 15. a groove; 16. installing a screw hole; 17. a cylindrical lumen; 18. a clamping groove; 19. a sinking groove; 20. a limiting hole; 21. a top plate; 22. a limit switch; 23. a screw; 24. a driving motor; 25. adjusting a screw; 26. a screw hole; 27. a through hole; 28. a movable block; 29. a slide block; 30. an upper press roll; 31. a chute; 32. a conveying roller; 33. a cable length calculating mechanism; 34. a disc nut; 35. a fixed roller; 36. a cross bar; 37. a movable roller; 38. and (5) screw threads.

Detailed Description

In the description, it should be understood that, if there is an azimuth or positional relationship indicated by terms such as "upper", "lower", "front", "rear", "left", "right", etc., the drawings merely correspond to the drawings of the present invention, and in order to facilitate description of the present invention, it is not necessary to indicate or imply that the apparatus or element to be referred to has a specific azimuth.

Referring to fig. 1-6 of the specification, the present invention provides a technical scheme:

an auxiliary device for laying an electric power transmission line comprises a base 7 and a cable drum 3, wherein an annular groove 12 is arranged on the upper surface of the base 7, a plurality of rolling elements 13 for supporting the cable drum 3 are uniformly distributed on the inner bottom surface of the annular groove 12, the rolling elements 13 are universal balls or rolling shafts consistent with the rotation direction of the cable drum 3, the vertically placed cable drum 3 is placed in the annular groove 12 on the base 7, a columnar inner cavity 17 is formed in the middle of the vertically placed cable drum 3, the upper end and the lower end of the columnar inner cavity 17 are of an open structure, a lifting bracket 2 is arranged on the upper part of the columnar inner cavity 17, a mounting screw hole 16 is formed in the upper part of the lifting bracket 2, a lifting hook 1 is in threaded connection with the mounting screw hole 16, stable lifting of the cable drum 3 can be realized through cooperation of lifting equipment and the lifting hook 1, in order to improve the stability in the lifting process of the cable drum 3, the lifting bracket 2 is of an isosceles trapezoid structure, the upper part of the base 7 is provided with a driving mechanism 6 for driving the cable tray 3 to rotate, the driving mechanism 6 is arranged in the middle of the annular groove 12 and is positioned in the columnar inner cavity 17, specifically, the driving mechanism 6 comprises a servo motor 9 and a driving rod 8, two sides of the inner wall of the lower part of the columnar inner cavity 17 are provided with corresponding clamping grooves 18, the lower end of the clamping groove 18 is of an open structure, the middle of the annular groove 12 is provided with the servo motor 9, the output end of the servo motor 9 is fixedly connected with the driving rod 8, when the cable tray 3 is vertically placed in the annular groove 12 through a lifting device, two ends of the driving rod 8 respectively correspond to the clamping grooves 18 on the inner walls of the two sides of the lower part of the columnar inner cavity 17, along with the lowering of the cable tray 3, the two ends of the driving rod 8 slide into the clamping grooves 18 through the openings of the lower ends of the clamping grooves 18, the servo motor 9 drives the driving rod 8 to rotate, and the clamping grooves 18 are matched with the driving rod 8, the cable drum 3 rotates in the annular groove 12, and the rolling piece 13 can greatly reduce the resistance in the rotating process of the cable drum 3; when different cable drums 3 are driven, the cable drum 3 can be driven in a rotating way only by replacing the driving rod 8 matched with the columnar inner cavity 17 of the cable drum 3;

the cable carding mechanism 5 is arranged on a rod body of the vertical rod 4 and can slide along the axial direction of the vertical rod 4, the cable carding mechanism 5 comprises a movable block 28, an upper press roller 30 and a conveying roller 32, a through hole 27 which penetrates through the movable block 28 and is matched with the vertical rod 4 is formed in the movable block 28, the upper press roller 30 and the conveying roller 32 for clamping conveying cables are arranged on one side of the movable block 28, as the cables have various diameters, in order to enable the upper press roller 30 and the conveying roller 32 to be matched with clamping conveying of cables with various diameters, a sliding groove 31 which is coaxially arranged with the vertical rod 4 is formed in one side of the movable block 28, an adjusting screw 25 which is coaxially arranged with the sliding groove 31 is arranged in the sliding groove 31, the lower end of the adjusting screw 25 is rotatably connected with the lower surface of the sliding groove 31, the upper end of the adjusting screw 25 penetrates through the sliding groove 31, a rotating handle is arranged at the end of the adjusting screw, the sliding groove 31 is internally provided with a sliding block 29 which is matched with the sliding groove 31, the upper press roller 30 is in threaded fit with the adjusting screw 25, the sliding block 29 is fixedly arranged on the sliding block 29, the sliding groove 29 is driven by rotation of the adjusting screw 25, the sliding block 29 is driven by the sliding groove 29 to be lifted and lowered by the adjusting screw 30, and lowered by the sliding of the adjusting screw 30, and the sliding roller 30 is driven by the sliding block 29, and the sliding roller 30 is regulated and lifted and lowered by the sliding roller 32;

a lifting adjusting mechanism for driving the cable carding mechanism 5 to lift and slide along the axial direction of the vertical rod 4 is arranged on one side of the vertical rod 4, the lifting adjusting mechanism comprises a screw rod 23 and a driving motor 24, the screw rod 23 parallel to the vertical rod 4 is arranged on one side of the vertical rod 4, the driving motor 24 for driving the screw rod 23 to rotate is arranged at the lower part of the screw rod 23, a screw hole 26 penetrating through the movable block 28 and in threaded fit with the screw rod 23 is arranged on the movable block 28, in order to realize the protection of the driving motor 24, a groove 15 is arranged on one side of the base 7, the driving motor 24 is arranged in the groove 15, and the lower end of the screw rod 23 is connected with an output shaft of the driving motor 24;

the cable drum 3 is in the rotation in-process of receiving or unwrapping wire, and the last compression roller 30 in the cable carding mechanism 5 cooperates with the conveying roller 32 to carry out the centre gripping to the cable, because the cable is spiral winding on the cable drum 3, and in the rotation of cable drum 3, lift adjustment mechanism drive cable carding mechanism 5 carries out reciprocal lift along with the winding orbit of cable on the cable drum 3 to realize the cable carding operation on the cable drum 3, avoid appearing the line ball condition when the rolling cable, appear the circumstances that the cable is not hard up drops on the cable drum 3 when the transfer cable.

For the second embodiment, for the winding or paying-off operation of the large-diameter cable, due to the heavy mass, the inertia generated by the cable drum 3 in the rotation process is large, in order to avoid the cable drum 3 from falling off from the annular groove 12, the bottom surface in the annular groove 12 is provided with the bottom annular groove 14, the cross section of the bottom annular groove 14 is of an inverted-T structure, the bottom annular groove 14 is internally provided with the bolt 11 sliding along the bottom annular groove 14, the bottom side plate of the vertically placed cable drum 3 is provided with the limit hole 20 matched with the bolt 11, the head of the bolt 11 penetrates through the limit hole 20 and is fixed through the nut 10, in order to ensure the flatness of the bottom side plate of the cable drum 3, the bottom side plate of the cable drum 3 is provided with the sinking groove 19, and the limit hole 20 is arranged on the inner bottom surface of the sinking groove 19.

In the third embodiment, since the cable on the cable tray 3 is spirally wound in a reciprocating manner, the cable carding mechanism 5 also needs to perform a reciprocating lifting motion, in order to realize that the cable carding mechanism 5 adapts to the height of the cable tray 3 to perform automatic lifting driving, the upper end of the vertical rod 4 is provided with a top plate 21, the upper end of the screw 23 is rotationally connected with the lower surface of the top plate 21, both the lower surface of the top plate 21 and the upper surface of the base are provided with limit switches 22 for touching the position of the sensing movable block 28 and controlling the driving motor 24 to reversely rotate; when the cable carding mechanism 5 slides up to the top along the vertical rod 4, the movable block 28 is in contact with the limit switch 22 on the lower surface of the top plate 21, the limit switch 22 receives a pressing signal and then controls the driving motor 24 to rotate reversely, the cable carding mechanism 5 slides downwards through the lifting adjusting mechanism, and then contacts the bottom limit switch 22 after descending to the lowest end, and then slides upwards reversely.

In order to enable the cable carding mechanism 5 to carry out effective conveying on cables with different diameters, the cables are prevented from sliding transversely between the upper pressing roller 30 and the conveying roller 32, the upper pressing roller 30 comprises a cross rod 36, a fixed roller 35, a movable roller 37 and a disc nut 34, the fixed roller 35 and the movable roller 37 are of conical structures, one end of the cross rod 36 is fixedly connected with the sliding block 29, the inner end of a rod body of the cross rod 36 is rotationally connected with the fixed roller 35, the outer end of the rod body of the cross rod 36 is rotationally connected with the movable roller 37 capable of sliding axially along the rod body, the fixed roller 35 is arranged opposite to the small end of the movable roller 37, threads 38 are arranged on the rod body of the cross rod 36, and the outer end of the cross rod 36 is provided with the disc nut 34 for adjusting the distance between the movable roller 37 and the fixed roller 35.

In the fifth embodiment, since the operator needs to know the cable conveying length during the conveying or winding process of the cable so as to cut the cable at the later stage, the operator manually calculates the cable length in a conventional manner, errors are easily generated, in order to realize accurate measurement of the cable conveying length, the outer end of the conveying roller 32 is provided with a cable length calculating mechanism 33 for calculating and displaying the cable conveying length by recording the rotation number of the conveying roller 32, the cable length calculating mechanism 33 comprises a winding number counter for counting the rotation number of the conveying roller 32, a processor for processing data, and a display for displaying a numerical value, the winding number counter counts the rotation number of the conveying roller 32 and transmits the count to the processor, and the processor receives the count information and multiplies the diameter of the conveying roller 32 to obtain the cable length numerical value and displays the cable length numerical value through the display.

The invention has not been described in detail in the prior art, and it is apparent to those skilled in the art that the invention is not limited to the details of the above-described exemplary embodiments, but that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof; the above-described embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. Auxiliary device is used in electric power transmission line laying, including base (7) and cable dish (3), its characterized in that: an annular groove (12) is formed in the upper portion of the base (7), a plurality of rolling elements (13) used for supporting the cable tray (3) and driving the cable tray (3) to rotate are evenly distributed on the inner bottom surface of the annular groove (12), the vertically placed cable tray (3) is placed in the annular groove (12) on the base (7), a columnar inner cavity (17) is formed in the middle of the vertically placed cable tray (3), the upper end and the lower end of the columnar inner cavity (17) are of an open structure, a lifting frame (2) is arranged on the upper portion of the columnar inner cavity (17), a detachable lifting hook (1) is arranged on the upper portion of the lifting frame (2), a driving mechanism (6) which is located in the columnar inner cavity (17) and drives the cable tray (3) to rotate is arranged in the middle of the annular groove (12), a bottom annular groove (14) is arranged on the inner bottom surface of the annular groove, the cross section of the bottom annular groove (14) is of an inverted T-shaped structure, a bolt (11) sliding along the bottom annular groove (14) is arranged in the bottom annular groove (14), a limit hole (20) matched with the bolt (11) is formed in the middle of the bottom side plate of the vertically placed cable tray (3), a limit hole (20) is formed in the upper portion of the column inner cavity, the upper portion of the vertical groove (17) is provided with a limit hole (20) matched with the bolt (11), one side of the vertical face (4) of the vertical face (7) is arranged through the vertical face (4), a cable carding mechanism (5) capable of sliding along the axial direction of the vertical rod (4) is arranged on the rod body of the vertical rod (4), a lifting adjusting mechanism for driving the cable carding mechanism (5) to lift and slide along the axial direction of the vertical rod (4) is arranged on one side of the vertical rod (4), and the cable carding mechanism (5) clamps a conveying cable in the rotation process of winding or unwinding the cable, and drives the cable carding mechanism to lift and move reciprocally through the lifting adjusting mechanism, so that the cable carding operation on the cable drum (3) is realized;

the driving mechanism (6) comprises a servo motor (9) and a driving rod (8), corresponding clamping grooves (18) are formed in two sides of the inner wall of the lower part of the columnar inner cavity (17), the lower end of each clamping groove (18) is of an open structure, the middle part of each annular groove (12) is provided with the servo motor (9), the output end of each servo motor (9) is fixedly connected with the driving rod (8), two ends of each driving rod (8) slide into the corresponding clamping groove (18) through the opening of the lower end of each clamping groove (18), and the driving cable tray (3) is driven by the corresponding servo motor (9) to rotate;

the cable carding mechanism (5) comprises a movable block (28), an upper press roll (30) and a conveying roll (32), a through hole (27) penetrating through the movable block (28) and being matched with a vertical rod (4) is formed in the movable block (28), the upper press roll (30) and the conveying roll (32) which are used for clamping a conveying cable and can adjust the clamping distance of the movable block (28) are arranged on one side of the movable block, the upper press roll (30) comprises a cross rod (36), a fixed roll (35), a movable roll (37) and a disc-shaped nut (34), the fixed roll (35) and the movable roll (37) are of conical structures, one end of the cross rod (36) is fixedly connected with a sliding block (29), the inner end of a rod body of the cross rod (36) is rotatably connected with the movable roll (37) which can axially slide along the rod body, the small end of the fixed roll (35) is arranged opposite to the small end of the movable roll (37), threads (38) are arranged on the rod body of the cross rod, the outer end of the cross rod (36) is provided with a recording roll (32) for calculating the length of the conveying cable, and calculating the length of the conveying roll (32) is displayed by the rotation length of the disc-shaped nut (32);

the lifting adjusting mechanism comprises a screw rod (23) and a driving motor (24), wherein one side of a vertical rod (4) is provided with the screw rod (23) parallel to the vertical rod (4), the lower part of the screw rod (23) is provided with the driving motor (24) for driving the screw rod (23) to rotate, the movable block (28) is provided with a screw hole (26) which penetrates through the movable block (28) and is in threaded fit with the screw rod (23), the upper end of the vertical rod (4) is provided with a top plate (21), the upper end of the screw rod (23) is rotationally connected with the lower surface of the top plate (21), and the lower surface of the top plate (21) and the upper surface of the base are both provided with limit switches (22) for touching the sensing movable block (28) and controlling the driving motor (24) to reversely rotate.