Safety alarm equipment for chemical experiment

Abstract

The utility model relates to safety alarm equipment for chemical experiments, which comprises a gas alarm body, a gas alarm shell is arranged at the outer end of the gas alarm body, and gas alarm terminals integrated with the gas alarm body are symmetrically arranged on two sides of the upper end of the gas alarm body; the two sides of the interior of the upper end of the gas alarm body are rotationally provided with connecting wire pulling prevention mechanisms, each connecting wire pulling prevention mechanism comprises a winding wheel, a rotating locking mechanism, a bearing seat, a winding wheel rotating shaft and a winding groove, the spiral winding groove is formed in the outer surface of the winding wheel, and the rotating locking mechanism is installed on the rear side of the winding wheel. The utility model relates to a gas alarm, and aims to solve the problems that in the prior art, when an experimenter performs experiment operation or maintains and upgrades laboratory equipment, misoperation possibly causes a signal line to be pulled, so that the signal line of the gas alarm is loosened, data transmission is interrupted or unstable, and internal elements of the alarm are damaged or aged.

Description

Technical Field

[0001] The utility model relates to the technical field of gas alarms, in particular to a chemical experiment safety alarm device. Background Art

[0002] Chemical laboratories are experimental sites and supporting facilities that provide conditions for chemical and chemical experiments and conduct scientific research, technological development, and other activities. The main function of chemical laboratories is to support experimental teaching, scientific research, and technological development in the field of chemical engineering and technology.

[0003] Chemical laboratory safety alarm equipment is used to monitor various potentially hazardous situations within chemical laboratories and sound an alarm when an abnormality is detected. These devices play a vital role in ensuring laboratory safety. Gas alarms in chemical experiments are crucial safety devices used to monitor the concentration of flammable, toxic, or hazardous gases that may be present in the laboratory and sound an alarm when the concentration reaches a preset safety threshold. Gas alarms operate based on sensor technologies such as electrochemistry, catalytic combustion, infrared absorption, or semiconductors. These sensors can sensitively capture the presence of specific gases in the air and convert their concentration into an electrical signal. When the detected gas concentration reaches the preset alarm threshold, the internal circuit of the alarm triggers an audible and visual alarm device. The alarm signal may also be transmitted via wired or wireless means to a monitoring center or the mobile device of relevant personnel, enabling remote monitoring and immediate response.

[0004] Existing safety alarm devices connect gas alarms to control systems via signal cables, transmitting detection signals to the control system in real time. Improper operation by laboratory personnel during experiments or when maintaining or upgrading laboratory equipment can cause the signal cables to become loose, disrupting or destabilizing data transmission, preventing the controller from receiving accurate data from the alarm. Furthermore, loose circuit instability can subject components within the alarm to excessive current or voltage fluctuations, leading to component damage or degradation. This damage can further impact the performance and lifespan of the alarm. Utility Model Content

[0005] In view of this, the purpose of the present utility model is to provide a chemical experiment safety alarm device to solve the problem in the prior art that improper operation by experimenters when performing experimental operations or maintaining and upgrading laboratory equipment may cause the signal line to be pulled, thereby causing the gas alarm signal line to loosen, resulting in data transmission interruption or instability and damage or aging of the internal components of the alarm.

[0006] The utility model is achieved through the following technical solutions:

[0007] A chemical experiment safety alarm device comprises a gas alarm body, a gas alarm housing is provided at the outer end of the gas alarm body, gas alarm connection terminals of an integral structure are symmetrically provided on both sides of the upper end of the gas alarm body, and an audible and visual alarm is connected to one side of the gas alarm connection terminal via a thread;

[0008] The connecting wire anti-pull mechanism is rotatably installed on both sides of the upper end of the gas alarm body. The connecting wire anti-pull mechanism includes a winding wheel, a rotation locking mechanism, a bearing seat, a winding wheel shaft and a winding groove. The outer surface of the winding wheel is provided with a spiral winding groove, and the rear side of the winding wheel is equipped with a rotation locking mechanism.

[0009] Furthermore, a gas sensor is fixedly installed at the lower end of the gas alarm shell, a main board is fixedly installed inside the gas alarm shell, a Hall sensor is installed on one side above the main board, the Hall sensor is electrically connected to the main board, the main board is electrically connected to the sound and light alarm, and the gas sensor is electrically connected to the main board.

[0010] Furthermore, two lead wheels are fixedly staggered inside the gas alarm terminal, the connecting wire anti-pull mechanism is located on one side of the lead wheel, one side of the sound and light alarm is connected to the sound and light alarm signal line, and a plurality of connecting terminals are provided at one end of the main board, one end of one of the connecting terminals is connected to the connecting wire, and the other connecting terminal is connected to the sound and light alarm signal line.

[0011] Furthermore, the winding wheel is located in the middle position of the connecting wire anti-pull mechanism, and the connecting wire and the sound and light alarm signal wire are both wound around the outside of the lead wheel and the winding wheel, and the connecting wire and the sound and light alarm signal wire are in contact with the winding groove.

[0012] Furthermore, bearing seats are installed on both sides of the winding wheel, and the interior of the winding wheel is connected to the winding wheel shaft through a key, and the bearing seats are rotatably connected to the winding wheel shaft.

[0013] Furthermore, the rotation locking mechanism includes a rotation locking mechanism shell, a rotation plate slot, a limit bar slot, a rotation plate, a limit bar, a positioning block, a sliding rod, a sliding rod movable slot, a sliding rod slot, a limit block, a compression spring, a sliding cap and a sliding cap slot. The outer end of the rotation locking mechanism is provided with a rotation locking mechanism shell, and the rotation locking mechanism shell is fixedly connected to the gas alarm shell. A rotation plate slot is provided inside the rotation locking mechanism shell, and three limit bar slots are provided in a ring shape on the outer side of the rotation plate slot. A rotation plate is installed at the center position inside the rotation plate slot, and the rotation plate is connected to the winding wheel shaft for transmission. Three limit bars are provided in a ring shape on the outer side of the rotation plate and are installed through rotation of the shaft.

[0014] The top end of the sliding plate is provided with a sliding groove, and the sliding plate is slidingly connected to the sliding plate by a spring.

[0015] The beneficial effects of the present invention are:

[0016] The chemical experiment safety alarm equipment can wind and reel the connecting wire and the sound and light alarm signal wire through the connecting wire anti-pull mechanism. After entering the gas alarm terminal, the connecting wire and the sound and light alarm signal wire first pass through the two lead wheels, thereby tightening the lead wheels, and then wind them in the winding groove of the winding wheel. At the same time, the surface of the winding wheel is fitted with a rubber layer, which can increase the friction between the winding wheel and the connecting wire and the sound and light alarm signal wire. When the connecting wire and the sound and light alarm signal wire are slowly pulled, the winding wheel will be driven to rotate along with the positioning of the winding wheel shaft. After the rotation, the winding wheel shaft will drive the rotating plate to rotate. At this time, the centrifugal force of the rotation is less than the elastic force of the compression spring, so that when the winding wheel shaft rotates, the limit bar will be compressed and elastic. The elastic force of the spring does not cause outward rotation, thereby not affecting the pulling of the connecting wire and the sound and light alarm signal wire, thereby enabling the installation and maintenance of the gas alarm body. However, when the connecting wire and the sound and light alarm signal wire are accidentally touched and pulled, the winding wheel will be driven to rotate rapidly, thereby causing the winding wheel shaft to rotate rapidly at the same time. The centrifugal force after rapid rotation is greater than the elastic force of the compression spring, allowing the sliding rod to slide in the direction of the limit bar, thereby pushing the limit bar to rotate outward along the axis between the rotating plate until the limit bar is in contact with the limit bar groove, thereby limiting the rotation angle of the rotating winding wheel shaft. Due to the setting of the rubber layer, the damage caused by the pulling force applied to the connecting wire and the sound and light alarm signal wire by the angle limit can be reduced through the flexible deformation of the rubber layer.

[0017] Other advantages, objectives, and features of the present invention will be described in detail in the following description and, to some extent, will be apparent to those skilled in the art upon examination and study of the following or may be learned from practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the main view of the utility model;

[0019] Figure 2 It is a structural diagram of the utility model;

[0020] Figure 3 This is a diagram showing the connection between the gas alarm housing and the connecting wire anti-pull mechanism in the present utility model;

[0021] Figure 4 It is a structural schematic diagram of the rotation locking mechanism in the utility model.

[0022] In the figure: 1. Gas alarm body; 2. Sound and light alarm; 3. Connecting wire; 4. Gas alarm terminal; 5. Gas alarm housing; 6. Gas sensor; 7. Main board; 8. Hall sensor; 9. Terminal; 10. Lead wheel; 11. Anti-pull mechanism for connecting wire; 12. Sound and light alarm signal line; 13. Winding wheel; 14. Rotation locking mechanism; 15. Bearing seat; 16. Winding wheel shaft; 17. Winding groove; 18. Rotation locking mechanism housing; 19. Rotating plate groove; 20. Limiting bar groove; 21. Rotating plate; 22. Limiting bar; 23. Positioning block; 24. Sliding rod; 25. Sliding rod movable groove; 26. Sliding rod slide groove; 27. Limiting block; 28. Compression spring; 29. ​​Sliding cap; 30. Sliding cap slide groove. DETAILED DESCRIPTION

[0023] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0026] In the above description of the present invention, it should be noted that the terms "one side" and "the other side" and the like indicate positions or locations based on the positions or locations shown in the accompanying drawings, or the positions or locations in which the product of the present invention is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" and the like are used solely for distinction and should not be construed as indicating or implying relative importance.

[0027] Furthermore, the term "identical" and similar terms do not necessarily require that the components be absolutely identical; slight variations are permitted. The term "perpendicular" simply refers to the positional relationship between components being more perpendicular than "parallel," not that the structure must be perfectly vertical; rather, it can be slightly tilted.

[0028] See also Figure 1-4 The utility model provides a technical solution: a chemical experiment safety alarm device, comprising a gas alarm body 1, a gas alarm housing 5 is provided at the outer end of the gas alarm body 1, and gas alarm terminals 4 with an integral structure therewith are symmetrically provided on both sides of the upper end of the gas alarm body 1, and an audible and visual alarm 2 is connected to one side of the gas alarm terminal 4 through a thread;

[0029] The connecting wire anti-pull mechanism 11 is rotatably installed on both sides of the upper end of the gas alarm body 1. The connecting wire anti-pull mechanism 11 includes a winding wheel 13, a rotation locking mechanism 14, a bearing seat 15, a winding wheel shaft 16 and a winding groove 17. The outer surface of the winding wheel 13 is provided with a spiral winding groove 17, and the rear side of the winding wheel 13 is equipped with a rotation locking mechanism 14;

[0030] The connecting wire 3 and the sound and light alarm signal line 12 can be wound and reeled through the connecting wire anti-pull mechanism 11. After the connecting wire 3 and the sound and light alarm signal line 12 enter the gas alarm terminal 4, they first pass around the two lead wheels 10 to tighten the lead wheel 10, and then are wound in the winding groove 17 of the winding wheel 13. At the same time, the surface of the winding wheel 13 is fitted with a rubber layer, which can increase the friction between the winding wheel 13 and the connecting wire 3 and the sound and light alarm signal line 12. When the connecting wire 3 and the sound and light alarm signal line 12 are slowly pulled, the winding wheel 13 will be driven to rotate along with the positioning of the winding wheel shaft 16. After rotation, the winding wheel shaft 16 will drive the rotating plate 21 to rotate. At this time, the centrifugal force of the rotation is less than the elastic force of the compression spring 28, so that when the winding wheel shaft 16 rotates, the limit bar 22 will be affected by the compression spring. The elastic force of 28 does not cause outward rotation, thereby not affecting the pulling of the connecting line 3 and the sound and light alarm signal line 12, thereby realizing the installation and maintenance operations of the gas alarm body 1. However, when the connecting line 3 and the sound and light alarm signal line 12 are accidentally touched and pulled, the winding wheel 13 will be driven to rotate rapidly, thereby causing the winding wheel shaft 16 to rotate rapidly at the same time. The centrifugal force after rapid rotation is greater than the elastic force of the compression spring 28, allowing the sliding rod 24 to slide in the direction of the limit bar 22, thereby pushing the limit bar 22 to rotate outward along the axis between the rotating plate 21 until the limit bar 22 is in contact with the limit bar groove 20, thereby limiting the rotation angle of the rotating winding wheel shaft 16. Due to the setting of the rubber layer, the damage caused by the pulling force applied to the connecting line 3 and the sound and light alarm signal line 12 by the angle limit can be reduced through the flexible deformation of the rubber layer.

[0031] In this embodiment, a gas sensor 6 is fixedly installed at the lower end of the gas alarm housing 5, a main board 7 is fixedly installed inside the gas alarm housing 5, a Hall sensor 8 is installed on one side above the main board 7, the Hall sensor 8 is electrically connected to the main board 7, the main board 7 is electrically connected to the sound and light alarm 2, and the gas sensor 6 is electrically connected to the main board 7.

[0032] The Hall sensor 8 can detect whether there is a magnetic field in the surrounding area and send it to the main board 7. When the Hall sensor 8 is powered on, the electrons in the current will be affected by the Lorentz force, causing the electron flow to deviate to one side when passing through the semiconductor, thereby generating a potential difference on both sides of the semiconductor chip, namely the Hall voltage. This Hall voltage is proportional to the strength of the magnetic field. In other words, the stronger the magnetic field, the higher the Hall voltage generated; the weaker the magnetic field, the lower the Hall voltage. By measuring the magnitude of the Hall voltage, the strength of the magnetic field can be indirectly measured. When the Hall sensor 8 detects the presence of a magnetic field in the surrounding area, the main board 7 receives the detection resistance and increases, and controls the sound and light alarm 2 to emit light and alarm, thereby warning the personnel in the laboratory to keep the equipment with magnetic field away from the gas alarm body 1, thereby reducing the damage caused by the magnetic field to the components in the gas alarm body 1.

[0033] In this embodiment, two lead wheels 10 are fixedly staggered inside the gas alarm terminal 4, the connecting wire anti-pull mechanism 11 is located on one side of the lead wheel 10, and one side of the sound and light alarm 2 is connected to the sound and light alarm signal line 12. A plurality of connecting terminals 9 are provided at one end of the main board 7, one end of one of the connecting terminals 9 is connected to the connecting wire 3, and the other connecting terminal 9 is connected to the sound and light alarm signal line 12.

[0034] The terminal 9 is used to connect the main board 7 with the connecting wire 3 and the sound and light alarm signal wire 12. Through the guidance of the two lead wheels 10 and the close setting of the two lead wheels 10, the tightness of the connecting wire 3 and the sound and light alarm signal wire 12 is limited due to friction, thereby assisting the connecting wire 3 and the sound and light alarm signal wire 12 on the surface of the winding wheel 13 to be tightened, so that the winding wheel 13 can limit the pulling of the connecting wire 3 and the sound and light alarm signal wire 12 through friction.

[0035] In this embodiment, the winding wheel 13 is located in the middle position of the connecting wire anti-pull mechanism 11, and the connecting wire 3 and the sound and light alarm signal line 12 are both wound around the outside of the lead wheel 10 and the winding wheel 13, and the connecting wire 3 and the sound and light alarm signal line 12 are in contact with the winding groove 17.

[0036] By setting the winding groove 17, the connecting line 3 and the sound and light alarm signal line 12 are confined inside it when winding, and at the same time, the contact area with the connecting line 3 and the sound and light alarm signal line 12 can be increased, thereby improving the friction between the connecting line 3 and the sound and light alarm signal line 12 and the winding wheel 13.

[0037] In this embodiment, bearing seats 15 are installed on both sides of the winding wheel 13. The interior of the winding wheel 13 is connected to the winding wheel shaft 16 through a key, and the bearing seats 15 are rotatably connected to the winding wheel shaft 16.

[0038] A bearing is installed inside the bearing seat 15, and the winding wheel shaft 16 and the bearing seat 15 are rotatably connected via the bearing. The bearing connection not only supports the winding wheel shaft 16 but also ensures its stability during rotation.

[0039] In this embodiment, the rotation locking mechanism 14 includes a rotation locking mechanism housing 18, a rotation plate groove 19, a limit bar groove 20, a rotation plate 21, a limit bar 22, a positioning block 23, a sliding rod 24, a sliding rod movable groove 25, a sliding rod slide 26, a limit block 27, a compression spring 28, a sliding cap 29 and a sliding cap slide 30. The outer end of the rotation locking mechanism 14 is provided with a rotation locking mechanism housing 18, and the rotation locking mechanism housing 18 is fixedly connected to the gas alarm housing 5. The rotation locking mechanism housing 18 is fixedly connected to the gas alarm housing 5. A rotating plate groove 19 is provided inside, and three limiting strip grooves 20 are provided in an annular manner on the outer side of the rotating plate groove 19. A rotating plate 21 is installed at the center position inside the rotating plate groove 19. The rotating plate 21 is transmission-connected to the winding wheel shaft 16. Three limiting strips 22 are provided in an annular manner on the outer side of the rotating plate 21 and are rotated by the rotating shaft. Three positioning blocks 23 are fixedly installed in an annular manner on one end of the rotating plate 21. A sliding rod slot 26 is provided inside the positioning block 23, and a sliding rod slot 26 is provided inside the sliding rod slot 26. A movable rod 24 is provided with a limit block 27 at one end of the sliding rod 24. The size of the limit block 27 is larger than the diameter of the sliding rod slot 26. A compression spring 28 is provided between the limit block 27 and the positioning block 23. The compression spring 28 is sleeved on the outside of the sliding rod 24. A sliding cap 29 is fixedly installed above the other end of the sliding rod 24. A sliding rod movable groove 25 is opened on the inner side of one end of the limit bar 22 away from the rotating shaft between the rotating plate 21. The sliding rod movable groove 25 is slidably connected to the sliding rod 24. A sliding cap slot 30 is provided above the rod movable slot 25, which passes through the limit bar 22. The sliding cap 29 is slidably connected to the sliding cap slot 30, and the lower end of the sliding cap 29 is fixedly connected to the limit bar 22. The upper end of the sliding cap 29 passes through and extends to the top of the sliding cap slot 30. The end of the sliding cap slot 30 away from the rotating axis between the rotating plate 21 and the limit bar 22 is inclined toward the rotating plate 21, and the end of the limit bar 22 away from the rotating axis between the rotating plate 21 and the limit bar 22 has the same inclination angle as the limit bar slot 20.

[0040] By setting the compression spring 28, the rotating plate 21 can rotate outward at a small angle through its own elastic force when rotating slowly, so that it does not enter the limit bar groove 20 and does not trigger the angle limit, thereby realizing the movement requirements of the connecting line 3 and the sound and light alarm signal line 12 for routine installation and inspection. When the rotating plate 21 rotates rapidly, the centrifugal force of the rotation is greater than the elastic force of the compression spring 28, thereby prompting the sliding rod 24 to extend outward, and the sliding cap 29 above one end of the sliding rod 24 slides under the limit of the sliding cap slot 30, thereby allowing the rotating plate 21 to rotate outward until it enters the sliding cap slot 30, thereby limiting the position of the rotating plate 21.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model and are not limiting. Although the utility model is described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A chemical experiment safety alarm device, comprising a gas alarm body (1), characterized in that: A gas alarm housing (5) is provided at the outer end of the gas alarm body (1), and gas alarm connection terminals (4) integrally formed therewith are symmetrically provided on both sides of the upper end of the gas alarm body (1), and an audible and visual alarm (2) is connected to one side of the gas alarm connection terminal (4) via a thread. A connecting wire anti-pull mechanism (11) is rotatably mounted on both sides of the interior of the upper end of the gas alarm body (1). The connecting wire anti-pull mechanism (11) comprises a winding wheel (13), a rotation locking mechanism (14), a bearing seat (15), a winding wheel shaft (16) and a winding groove (17). A spiral winding groove (17) is provided on the outer surface of the winding wheel (13), and a rotation locking mechanism (14) is mounted on the rear side of the winding wheel (13).

2. The chemical experiment safety alarm device according to claim 1, characterized in that: A gas sensor (6) is fixedly mounted on the lower end of the gas alarm housing (5), a mainboard (7) is fixedly mounted inside the gas alarm housing (5), a Hall sensor (8) is mounted on one side above the mainboard (7), the Hall sensor (8) is electrically connected to the mainboard (7), the mainboard (7) is electrically connected to the sound and light alarm (2), and the gas sensor (6) is electrically connected to the mainboard (7).

3. The chemical experiment safety alarm device according to claim 2, characterized in that: Two lead wheels (10) are fixedly staggered inside the gas alarm terminal (4), the connecting wire anti-pull mechanism (11) is located on one side of the lead wheel (10), one side of the sound and light alarm (2) is connected to a sound and light alarm signal line (12), and one end of the main board (7) is provided with a plurality of connecting terminals (9), one end of one of the connecting terminals (9) is connected to a connecting wire (3), and the other connecting terminal (9) is connected to the sound and light alarm signal line (12).

4. The chemical experiment safety alarm device according to claim 3, characterized in that: The winding wheel (13) is located in the middle of the connecting wire anti-pull mechanism (11); the connecting wire (3) and the sound and light alarm signal line (12) are both wound around the outside of the lead wheel (10) and the winding wheel (13); and the connecting wire (3) and the sound and light alarm signal line (12) are in contact with the winding groove (17).

5. The chemical experiment safety alarm device according to claim 4, characterized in that: Bearing seats (15) are installed on both sides of the winding wheel (13), and the interior of the winding wheel (13) is connected to the winding wheel shaft (16) through a key, and the bearing seat (15) is rotatably connected to the winding wheel shaft (16).

6. The chemical experiment safety alarm device according to claim 1, characterized in that: The rotation locking mechanism (14) comprises a rotation locking mechanism housing (18), a rotation plate slot (19), a limit bar slot (20), a rotation plate (21), a limit bar (22), a positioning block (23), a sliding rod (24), a sliding rod movable slot (25), a sliding rod sliding slot (26), a limit block (27), a compression spring (28), a sliding cap (29) and a sliding cap sliding slot (30). The outer end of the rotation locking mechanism (14) is provided with a rotation locking mechanism housing (18). The rotation locking mechanism The mechanism housing (18) is fixedly connected to the gas alarm housing (5); a rotating plate groove (19) is provided inside the rotating locking mechanism housing (18); three limiting strip grooves (20) are provided in an annular shape on the outer side of the rotating plate groove (19); a rotating plate (21) is installed at the center position inside the rotating plate groove (19); the rotating plate (21) is transmission-connected to the winding wheel shaft (16); and three limiting strips (22) are provided in an annular shape on the outer side of the rotating plate (21) and are rotatably installed via the shaft.

7. The chemical experiment safety alarm device according to claim 6, characterized in that: One end of the rotating plate (21) is annularly fixedly mounted with three positioning blocks (23), the interior of the positioning block (23) is provided with a sliding rod slot (26), the interior of the sliding rod slot (26) is slidably mounted with a sliding rod (24), one end of the sliding rod (24) is provided with a limiting block (27), the size of the limiting block (27) is larger than the diameter of the sliding rod slot (26), a compression spring (28) is provided between the limiting block (27) and the positioning block (23), the compression spring (28) is sleeved on the outside of the sliding rod (24), a sliding cap (29) is fixedly mounted above the other end of the sliding rod (24), and the inner side of the end of the limiting bar (22) away from the rotating shaft between the rotating plate (21) is provided with a sliding rod The movable groove (25) is slidingly connected to the sliding rod (24). A sliding cap groove (30) is provided above the movable groove (25) of the sliding rod and penetrates the limit bar (22). The sliding cap (29) is slidingly connected to the sliding cap groove (30). The lower end of the sliding cap (29) is fixedly connected to the limit bar (22). The upper end of the sliding cap (29) penetrates and extends to the top of the sliding cap groove (30). One end of the sliding cap groove (30) away from the rotating shaft between the rotating plate (21) and the limit bar (22) is inclined toward the rotating plate (21). The one end of the limit bar (22) away from the rotating shaft between the rotating plate (21) and the limit bar (22) has the same inclination angle as the limit bar groove (20).

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