Automatic screw assembling machine

Abstract

The utility model belongs to the technical field of screw assembling, and particularly relates to an automatic screw assembling machine which comprises a bottom plate, and an assembling mechanism is arranged on the bottom plate. A feeding mechanism is arranged on one side of the bottom plate; through cooperation of a photoelectric switch, a sleeve rod and a limiting rod, a first motor rotates a screwdriver to the horizontal direction every time after an inner hexagonal threaded hole is screwed into a threaded hole of a product; when the jackscrews are fed, the jackscrews are orderly conveyed to the conveying belt through the vibration disc, when the conveying belt drives the jackscrews to move and the jackscrews are aligned with the axes of the photoelectric switches, the conveying belt is closed through the photoelectric switches, then the electric push rods are started, and the output ends of the electric push rods drive the limiting rods and the sleeve rods to move; the limiting rod and the sleeve rod enter the inner hexagon of the jackscrew, in the movement process of the limiting rod, the jackscrew slightly rotates until the jackscrew rotates to the horizontal direction, the rotation angle of the jackscrew is the same as that of the screwdriver, and the function that the screwdriver and an inner hexagon threaded hole are aligned through rapid adjustment is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of screw assembly, in particular to an automatic screw assembly machine. Background Art

[0002] In the assembly process of household appliances, mechanical products, low-voltage electrical products, children's toys and other products, screw connection is the most common means. Therefore, in the assembly process of these products, screw assembly becomes one of the most basic operations.

[0003] A Chinese patent with announcement number CN206316706U discloses an automatic top screw assembly and cutting material structure; it includes a base; a slider; a propulsion cylinder; a mounting seat; a feed seat; an electric wrench, which is horizontally arranged on the slider, and has a locking rod at the end of the electric wrench and the locking rod can be inserted into the through hole; in this utility model, the top screw is directionally fed into the feed seat through a vibrating disk, enters the through hole through the feed port in the feed seat, and then is sent to the top screw hole of the workpiece through the horizontally installed hexagonal electric wrench locking rod, thereby shortening the stroke of the top screw from the divider to the workpiece screw hole as much as possible, making the top screw movement more stable and improving work efficiency.

[0004] In the above technology, the top screw is dropped in order on the feed seat, feed port and through hole through the vibration plate, but the threaded hole opened inside the top screw is hexagonal. During the blanking process, the angles of the top screw are different. When the top screw is sent to the top screw hole of the workpiece through the hexagonal electric wrench locking rod, the hexagonal electric wrench locking rod and the threaded hole may be staggered with each other, and the hexagonal electric wrench locking rod cannot be directly inserted into the threaded hole, and the hexagonal electric wrench locking rod is easily damaged.

[0005] Therefore, a screw automatic assembly machine is proposed to address the above problems. Utility Model Content

[0006] In order to make up for the shortcomings of the existing technology and solve the problem that the locking rod of the hexagonal electric wrench and the threaded hole may be staggered and it is impossible to ensure that the locking rod of the hexagonal electric wrench is directly inserted into the threaded hole, an automatic screw assembly machine is proposed.

[0007] The technical solution adopted by the utility model to solve its technical problems is: the automatic screw assembly machine described in the utility model includes a base plate, and an assembly mechanism is provided on the base plate; a feeding mechanism is provided on one side of the base plate, and the feeding mechanism includes a conveyor belt, and the conveyor belt is installed on a frame, and a photoelectric switch is fixedly connected to the inner wall of the frame, and a side plate is fixedly connected to the outer wall of the frame, and an electric push rod is fixedly connected to the top of the side plate, and the output shaft of the electric push rod is fixedly connected to a limit rod, and a sleeve rod is fixedly connected to the end of the limit rod away from the electric push rod, and splints are provided on both sides of the sleeve rod.

[0008] Preferably, two fixed frames are fixedly connected to the top of the frame, and the top inner walls of the two fixed frames are fixedly connected with electric slide rails, and the electric slide rails are slidably connected to the sliding frame, and the sliding frame is rotatably connected to the bidirectional ball screw through a bearing, and a second motor is fixed to the side wall of the sliding frame, and the output shaft of the second motor is fixed to one end of the bidirectional ball screw; two movable plates are threadedly connected to the bidirectional ball screw, and the splints are slidably connected to the bottom end of the movable plate through electric telescopic rods; two guide rods are fixed to the inner side wall of the sliding frame, and the movable plates are both slidably connected to the two guide rods.

[0009] Preferably, the assembly mechanism includes a guide rail fixedly connected to the top of the base plate, a first slider and a second slider are slidably connected to the guide rail, a first mounting plate is fixedly connected to the first slider, a telescopic plate is fixedly connected to the second slider, a first motor is fixedly connected to the side wall of the first mounting plate away from the telescopic plate, an output shaft of the first motor is rotatably connected to the first mounting plate through a bearing and extends through the first mounting plate, a coupling is fixedly connected to the output shaft of the first motor, a screwdriver quick connector is fixedly connected to one end of the screwdriver quick connector, a screwdriver is installed at one end of the screwdriver quick connector; an air suction nozzle is installed on the side wall of the telescopic plate away from the first mounting plate, the screwdriver moves in the air suction nozzle, and one end of the air suction nozzle is connected to an air pump through a delivery pipe.

[0010] Preferably, a second mounting plate is fixed to the top of the base plate, a first cylinder is fixed to the second mounting plate, an output end of the first cylinder extends through the second mounting plate and is fixed to a second telescopic rod, one end of the second telescopic rod is fixed to the first mounting plate, one end of the second telescopic rod is sleeved with a second spring, and one end of the second spring is fixed to the first mounting plate.

[0011] Preferably, a second cylinder is fixedly connected to the first mounting plate, the output end of the second cylinder extends through the first mounting plate and is fixedly connected to a first telescopic rod, one end of the first telescopic rod is fixedly connected to the telescopic plate, one end of the first telescopic rod is sleeved with a first spring, and one end of the first spring is fixedly connected to the telescopic plate.

[0012] Preferably, a limiting block is fixed to the top of the bottom plate, and the limiting block cooperates with the telescopic plate.

[0013] Beneficial effects of the utility model:

[0014] The utility model provides an automatic screw assembly machine. The cooperation of a photoelectric switch, a sleeve rod and a limit rod solves the problem of inconvenient alignment of a screwdriver and a hexagonal inner threaded hole. Each time a first motor completes screwing the hexagonal inner threaded hole into the threaded hole of a product, the screwdriver is rotated to a horizontal direction. At the same time, when a top screw is loaded, the top screw is transported in an orderly manner on a conveyor belt through a vibrating disk. When the conveyor belt drives the top screw to move, when the top screw is aligned with the axis of the photoelectric switch, the conveyor belt is closed through the photoelectric switch, and then an electric push rod is turned on. The output end of the electric push rod drives the limit rod and the sleeve rod to move. The limit rod and the sleeve rod enter the hexagonal inner thread of the top screw. During the movement of the limit rod, the top screw rotates slightly until it rotates to a horizontal direction with the same rotation angle as the screwdriver. Then, the top screw is clamped to the front of the screwdriver by a clamping plate, thereby realizing the function of quickly adjusting the alignment of the screwdriver and the hexagonal inner threaded hole.

[0015] The utility model provides an automatic screw assembly machine, which cooperates with an air suction nozzle and a screwdriver. During the assembly process, the second air cylinder drives the first telescopic rod to move through the output end, and the first telescopic rod compresses the first spring during the movement, and at the same time drives the telescopic plate to move, and drives the air suction nozzle to move through the telescopic plate, and the air suction nozzle moves to one side of the top screw, and sucks the top screw between the splints through the air suction nozzle; then the second air cylinder drives the first telescopic rod to move through the output end, and the first telescopic rod compresses the first spring during the movement, and at the same time drives the telescopic plate to move, and drives the air suction nozzle to move through the telescopic plate, and the air suction nozzle is pressed onto the threaded hole of the product; the first air cylinder drives the second telescopic rod to move through the output end, and the second telescopic rod compresses the second spring to drive the first mounting plate to move, and the first mounting plate drives the first motor to move, and the first motor drives the coupling, the screwdriver quick connector, and the screwdriver to move. When the screwdriver head is pushed into the threaded hole of the hexagonal top screw, the first motor rotates at this time, and the hexagonal top screw is screwed into the threaded hole of the product through the coupling, the screwdriver quick connector, and the screwdriver, thereby realizing rapid assembly of the top screw. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 It is a three-dimensional diagram of the utility model;

[0018] Figure 2 It is a partial three-dimensional diagram of the present utility model;

[0019] Figure 3 It is a cross-sectional view of the screwdriver in the utility model;

[0020] Figure 4It is a three-dimensional diagram of the first mounting plate in the present utility model;

[0021] Figure 5 It is a three-dimensional diagram of the splint in the utility model;

[0022] Figure 6 It is a three-dimensional diagram of the limiting rod in the utility model;

[0023] Legend:

[0024] 1. Base plate; 2. Guide rail; 3. Telescopic plate; 4. First mounting plate; 5. Second mounting plate; 6. First cylinder; 7. First motor; 8. Second cylinder; 9. First telescopic rod; 10. First spring; 11. Coupling; 12. Screwdriver quick connector; 13. Screwdriver; 14. First slider; 15. Limit block; 16. Air suction nozzle; 17. Second slider; 18. Second spring; 19. Second telescopic rod; 20. Conveyor belt; 21. Fixed bracket; 22. Electric slide rail; 23. Sliding bracket; 24. Second motor; 25. Bidirectional ball screw; 26. Guide rod; 27. Clamp; 28. Photoelectric switch; 29. Sleeve rod; 30. Limit rod; 31. Electric push rod; 32. Side plate; 33. Moving plate. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] Specific examples are given below. Example 1

[0027] See also Figures 1-6 The utility model provides a screw automatic assembly machine, including a base plate 1, on which an assembly mechanism is provided; a loading mechanism is provided on one side of the base plate 1, and the loading mechanism includes a conveyor belt 20, which is installed on a frame, and a photoelectric switch 28 is fixedly connected to the inner side wall of the frame, and a side plate 32 is fixedly connected to the outer side wall of the frame, and an electric push rod 31 is fixedly connected to the top of the side plate 32, and the output shaft of the electric push rod 31 is fixedly connected to a limit rod 30, and a sleeve rod 29 is fixedly connected to the end of the limit rod 30 away from the electric push rod 31, and clamping plates 27 are provided on both sides of the sleeve rod 29.

[0028] When working, in order to solve the problem that the screwdriver 13 is inconvenient to align with the hexagonal threaded hole, the first motor 7 rotates the screwdriver 13 to the horizontal direction each time the hexagonal threaded hole is screwed into the threaded hole of the product. At the same time, when the top screw is loading, the top screw is transported to the conveyor belt 20 in an orderly manner through the vibrating disk. When the conveyor belt 20 drives the top screw to move, when the top screw is aligned with the axis of the photoelectric switch 28, the conveyor belt 20 is closed through the photoelectric switch 28, and then the electric push rod 31 is turned on. The output end of the electric push rod 31 drives the limit rod 30 and the sleeve rod 29 to move. The limit rod 30 and the sleeve rod 29 enter the hexagonal inner corner of the top screw. During the movement of the limit rod 30, the top screw rotates slightly until it rotates to the horizontal direction, which is the same as the rotation angle of the screwdriver 13. Then, the top screw is clamped to the front of the screwdriver 13 by the clamping plate 27, thereby realizing the function of quickly adjusting the screwdriver 13 to align with the hexagonal threaded hole.

[0029] Further, such as Figure 5 As shown, two fixed frames 21 are fixed to the top of the frame, and the top inner walls of the two fixed frames 21 are fixed with electric slide rails 22, and the electric slide rails 22 are slidably connected to the sliding frames 23, and the sliding frames 23 are rotatably connected to the bidirectional ball screws 25 through bearings, and the side walls of the sliding frames 23 are fixed with a second motor 24, and the output shaft of the second motor 24 is fixed to one end of the bidirectional ball screw 25; two movable plates 33 are threadedly connected to the bidirectional ball screw 25, and the splints 27 are slidably connected to the bottom ends of the movable plates 33 through electric telescopic rods; two guide rods 26 are fixed to the inner side walls of the sliding frames 23, and the movable plates 33 are both slidably connected to the two guide rods 26.

[0030] During operation, after the top screw is aligned by the limit rod 30, the electric telescopic rod is driven to drive the splint 27 to move downward to the surface of the conveyor belt 20, and then the second motor 24 is turned on, and the bidirectional ball screw 25 is driven to rotate by the second motor 24, and the two movable plates 33 are driven to move in opposite directions by the bidirectional ball screw 25, and the splint 27 is driven to move in opposite directions by the movable plate 33 until the splint 27 clamps the top screw, and the electric slide rail 22 is driven to move the sliding frame 23, the splint 27 and the top screw by the electric slide rail 22 until they move to the front of the air suction nozzle 16, so as to facilitate the suction of the air suction nozzle 16; during the movement of the movable plate 33, the movable plate 33 slides on the guide rod 26, and the guide rod 26 limits the movable plate 33 in the horizontal direction. Example 2

[0031] Further, such as Figure 2 and Figure 3As shown, the assembly mechanism includes a guide rail 2 fixed to the top of the base plate 1, and a first slider 14 and a second slider 17 are slidably connected to the guide rail 2, the first slider 14 is fixed to the first mounting plate 4, and the second slider 17 is fixed to the telescopic plate 3, and the side wall of the first mounting plate 4 away from the telescopic plate 3 is fixed to the first motor 7, and the output shaft of the first motor 7 is rotatably connected to the first mounting plate 4 through a bearing and extends through the first mounting plate 4, and the output shaft of the first motor 7 is fixed to a coupling 11, and one end of the coupling 11 is fixed to a screwdriver quick connector 12, and one end of the screwdriver quick connector 12 is installed with a screwdriver 13; an air suction nozzle 16 is installed on the side wall of the telescopic plate 3 away from the first mounting plate 4, and the screwdriver 13 moves in the air suction nozzle 16, and one end of the air suction nozzle 16 is connected to an air pump through a delivery pipe.

[0032] During operation, during the assembly process, the second cylinder 8 drives the first telescopic rod 9 to move through the output end, and the first telescopic rod 9 compresses the first spring 10 during the movement, and at the same time drives the telescopic plate 3 to move, and drives the air suction nozzle 16 to move through the telescopic plate 3, and the air suction nozzle 16 moves to one side of the top screw, and sucks the top screw between the splints 27 through the air suction nozzle 16; then the second cylinder 8 drives the first telescopic rod 9 to move through the output end, and the first telescopic rod 9 compresses the first spring 10 during the movement, and at the same time drives the telescopic plate 3 to move, and drives the air suction nozzle 16 to move through the telescopic plate 3, and the air suction The nozzle 16 is pressed onto the threaded hole of the product; the first cylinder 6 drives the second telescopic rod 19 to move through the output end, the second telescopic rod 19 compresses the second spring 18 to drive the first mounting plate 4 to move, the first mounting plate 4 drives the first motor 7 to move, the first motor 7 drives the coupling 11, the screwdriver quick connector 12, and the screwdriver 13 to move. When the head of the screwdriver 13 is pushed into the threaded hole of the hexagonal screw, the first motor 7 rotates at this time, and through the coupling 11, the screwdriver quick connector 12, and the screwdriver 13, the hexagonal screw is screwed into the threaded hole of the product, thereby realizing the rapid assembly of the screw.

[0033] Further, such as Figure 2 As shown, a second mounting plate 5 is fixed to the top of the base plate 1, a first cylinder 6 is fixed to the second mounting plate 5, an output end of the first cylinder 6 extends through the second mounting plate 5, and is fixed to a second telescopic rod 19, one end of the second telescopic rod 19 is fixed to the first mounting plate 4, one end of the second telescopic rod 19 is sleeved with a second spring 18, and one end of the second spring 18 is fixed to the first mounting plate 4.

[0034] During operation, in order to drive the first motor 7 to move on the guide rail 2, the first cylinder 6 is turned on, and the first cylinder 6 drives the second telescopic rod 19 to move through the output end. The second telescopic rod 19 compresses the second spring 18 to drive the first mounting plate 4 to move, and the first mounting plate 4 drives the first motor 7 to move.

[0035] Further, such as Figure 2 As shown, a second cylinder 8 is fixedly connected to the first mounting plate 4, and an output end of the second cylinder 8 extends through the first mounting plate 4 and is fixedly connected to a first telescopic rod 9, one end of the first telescopic rod 9 is fixedly connected to the telescopic plate 3, and one end of the first telescopic rod 9 is sleeved with a first spring 10, and one end of the first spring 10 is fixedly connected to the telescopic plate 3.

[0036] During operation, in order to drive the air suction nozzle 16 to move on the guide rail 2, the second cylinder 8 is turned on, and the second cylinder 8 drives the first telescopic rod 9 to move through the output end. The first telescopic rod 9 compresses the first spring 10 to drive the telescopic plate 3 to move, and the telescopic plate 3 drives the air suction nozzle 16 to move.

[0037] Further, such as Figure 2 As shown, a limit block 15 is fixed to the top of the bottom plate 1 , and the limit block 15 cooperates with the telescopic plate 3 .

[0038] During operation, the telescopic plate 3 is limited by the limiting block 15 to prevent the telescopic plate 3 from sliding out of the guide rail 2.

[0039] Working principle: In order to solve the problem of inconvenient alignment of the screwdriver 13 and the hexagonal threaded hole, the first motor 7 rotates the screwdriver 13 to the horizontal direction each time the hexagonal threaded hole is screwed into the threaded hole of the product; at the same time, when the top screw is loaded, the top screw is transported to the conveyor belt 20 in an orderly manner through the vibration plate. When the conveyor belt 20 drives the top screw to move, when the top screw is aligned with the axis of the photoelectric switch 28, the conveyor belt 20 is closed through the photoelectric switch 28, and then the electric push rod 31 is turned on. The output end of the electric push rod 31 drives the limit rod 30 and the sleeve rod 29 to move. The limit rod 30 and the sleeve rod 29 enter the hexagonal inner corner of the top screw. During the movement of the limit rod 30, the top screw rotates slightly until it rotates to the horizontal direction and is aligned with the screw The rotation angles of the batches 13 are the same; then, the electric telescopic rod is driven to drive the splint 27 to move downward to the surface of the conveyor belt 20, and then the second motor 24 is turned on, and the bidirectional ball screw 25 is driven to rotate by the second motor 24, and the two movable plates 33 are driven to move in opposite directions by the bidirectional ball screw 25, and the splints 27 are driven to move in opposite directions by the movable plates 33 until the splints 27 clamp the top screw, and the electric slide rail 22 is driven to move the sliding frame 23, the splint 27 and the top screw by the electric slide rail 22 until they move to the front of the air suction nozzle 16, so as to facilitate the suction of the air suction nozzle 16; during the movement of the movable plate 33, the movable plate 33 slides on the guide rod 26, and the guide rod 26 limits the movable plate 33 in the horizontal direction;

[0040] During the assembly process, the second cylinder 8 drives the first telescopic rod 9 to move through the output end. The first telescopic rod 9 compresses the first spring 10 during the movement, and at the same time drives the telescopic plate 3 to move, and drives the air suction nozzle 16 to move through the telescopic plate 3. The air suction nozzle 16 moves to one side of the top screw and sucks the top screw between the splints 27 through the air suction nozzle 16; then the second cylinder 8 drives the first telescopic rod 9 to move through the output end. The first telescopic rod 9 compresses the first spring 10 during the movement, and at the same time drives the telescopic plate 3 to move, and drives the air suction nozzle 16 to move through the telescopic plate 3. 6 is pressed to the threaded hole of the product; the first cylinder 6 drives the second telescopic rod 19 to move through the output end, the second telescopic rod 19 compresses the second spring 18 to drive the first mounting plate 4 to move, the first mounting plate 4 drives the first motor 7 to move, the first motor 7 drives the coupling 11, the screwdriver quick connector 12, and the screwdriver 13 to move. When the head of the screwdriver 13 is pushed into the threaded hole of the hexagonal screw, the first motor 7 rotates at this time, and the hexagonal screw is screwed into the threaded hole of the product through the coupling 11, the screwdriver quick connector 12, and the screwdriver 13, thereby realizing the rapid assembly of the screw.

[0041] 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 are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the present invention as claimed.

Claims

1. A screw automatic assembly machine, comprising a base plate (1), an assembly mechanism being provided on the base plate (1); a feeding mechanism being provided on one side of the base plate (1), characterized in that: The feeding mechanism comprises a conveyor belt (20), the conveyor belt (20) being mounted on a frame, a photoelectric switch (28) being fixedly connected to the inner side wall of the frame, a side plate (32) being fixedly connected to the outer side wall of the frame, an electric push rod (31) being fixedly connected to the top of the side plate (32), an output shaft of the electric push rod (31) being fixedly connected to a limit rod (30), an end of the limit rod (30) away from the electric push rod (31) being fixedly connected to a sleeve rod (29), and clamping plates (27) being provided on both sides of the sleeve rod (29).

2. The automatic screw assembly machine according to claim 1, characterized in that: Two fixed frames (21) are fixedly connected to the top of the frame, and electric slide rails (22) are fixedly connected to the inner walls of the tops of the two fixed frames (21). A sliding frame (23) is slidably connected to the electric slide rails (22), and a bidirectional ball screw (25) is rotatably connected to the sliding frame (23) through a bearing. A second motor (24) is fixedly connected to the side wall of the sliding frame (23), and the output shaft of the second motor (24) is fixedly connected to one end of the bidirectional ball screw (25); two movable plates (33) are threadedly connected to the bidirectional ball screw (25), and the clamping plates (27) are respectively slidably connected to the bottom ends of the movable plates (33) through electric telescopic rods; two guide rods (26) are fixedly connected to the inner side wall of the sliding frame (23), and the movable plates (33) are both slidably connected to the two guide rods (26).

3. The automatic screw assembly machine according to claim 2, characterized in that: The assembly mechanism comprises a guide rail (2) fixed to the top of the base plate (1), a first slider (14) and a second slider (17) being slidably connected to the guide rail (2), a first mounting plate (4) being fixed to the first slider (14), a telescopic plate (3) being fixed to the second slider (17), a first motor (7) being fixed to a side wall of the first mounting plate (4) away from the telescopic plate (3), an output shaft of the first motor (7) being rotatably connected to the first mounting plate (4) through a bearing and extending through the first mounting plate (4), a coupling (11) being fixed to the output shaft of the first motor (7), a screwdriver quick connector (12) being fixed to one end of the screwdriver quick connector (12), a screwdriver (13) being mounted on one end of the screwdriver quick connector (12); an air suction nozzle (16) being mounted on the side wall of the telescopic plate (3) away from the first mounting plate (4), the screwdriver (13) moving in the air suction nozzle (16), and an air pump being externally connected to one end of the air suction nozzle (16) through a delivery pipe.

4. The automatic screw assembly machine according to claim 3, characterized in that: A second mounting plate (5) is fixedly connected to the top of the base plate (1), a first cylinder (6) is fixedly connected to the second mounting plate (5), an output end of the first cylinder (6) extends through the second mounting plate (5) and is fixedly connected to a second telescopic rod (19), one end of the second telescopic rod (19) is fixedly connected to the first mounting plate (4), one end of the second telescopic rod (19) is sleeved with a second spring (18), and one end of the second spring (18) is fixedly connected to the first mounting plate (4).

5. The automatic screw assembly machine according to claim 4, characterized in that: A second cylinder (8) is fixedly connected to the first mounting plate (4), an output end of the second cylinder (8) extends through the first mounting plate (4) and is fixedly connected to a first telescopic rod (9), one end of the first telescopic rod (9) is fixedly connected to the telescopic plate (3), one end of the first telescopic rod (9) is sleeved with a first spring (10), and one end of the first spring (10) is fixedly connected to the telescopic plate (3).

6. The automatic screw assembly machine according to claim 5, characterized in that: A limiting block (15) is fixedly connected to the top of the bottom plate (1), and the limiting block (15) cooperates with the telescopic plate (3).

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