CN115541392B

CN115541392B - Fireproof cable core tension test device

Info

Publication number: CN115541392B
Application number: CN202211516280.2A
Authority: CN
Inventors: 梁明春; 李平; 梁显伟; 黄卓金
Original assignee: Guangdong Tianhong Cable Co ltd
Current assignee: Guangdong Tianhong Cable Co ltd
Priority date: 2022-11-30
Filing date: 2022-11-30
Publication date: 2023-02-24
Anticipated expiration: 2042-11-30
Also published as: CN115541392A

Abstract

The invention relates to a device for testing tension of a cable core, in particular to a tension test device for a fireproof cable core. The invention aims to provide a tensile test device for a core of a fireproof cable, which can stop the core of the cable after the core of the cable is broken, ensure the detection result, and has simple structure and low failure rate. The invention provides a tensile test device for a core of a fireproof cable, which comprises a workbench, a hydraulic cylinder and a tension meter, wherein the hydraulic cylinder is arranged on one side of the top of the workbench, and a piston rod of the hydraulic cylinder is connected with the tension meter. When the device is operated, the circuit can be supplied through the cable core, and when the cable core is broken, the circuit can be stopped from being communicated, so that the electromagnet and the hydraulic cylinder can stop running, the phenomenon that the clamp continues to drive the cable core to move to influence the detection of the tensile length of the cable core is avoided, and the judgment of the tensile value of the cable core can also be ensured.

Description

Fireproof cable core tension test device

Technical Field

The invention relates to a device for testing tension of a cable core, in particular to a tension test device for a fireproof cable core.

Background

The fire prevention cable core is because of needs long-term use, and the intensity of cable core is very important, otherwise easily because of long-term use, influences the transmission of electric energy, consequently, finishes the back at fire prevention cable core preparation, needs carry out the tensile test to fire prevention cable's sinle silk.

At present, the mode that carries out the tensile test to the cable core is CN214040938U like the patented patent publication number, discloses a tension test device for cable detection, tests, but above-mentioned patent is difficult to close hydraulic cylinder immediately after the cable core stretches out, and this piston rod that will lead to its hydraulic cylinder continues to extend to continue to drive the cable core that stretches out and remove, this detection to the tensile length of cable core that just influences easily, also can influence the judgement to cable core tensile value.

The testing is also carried out by using the tensile testing method and the tensile equipment for the core of the mineral insulated flexible fireproof cable disclosed by the patent publication No. CN112924272A, the defect that a hydraulic oil cylinder is difficult to close immediately after the testing is finished also exists in the patent, the piston rod of the hydraulic oil cylinder can be caused to extend continuously, but the device realizes the testing of the tensile value of the core of the cable through a plurality of electric control equipment, the cost is overhigh during production and manufacturing, the tensile testing of the core of the cable is realized through the electric control equipment, and the failure rate is higher.

Disclosure of Invention

In view of this, the invention provides a tensile test device for a core of a fireproof cable, which can stop moving the core of the cable after the core of the cable is broken, so as to ensure a detection result, and has a simple structure and a low failure rate.

The technical scheme is as follows: the utility model provides a fire prevention cable core tensile test device, including workstation, pneumatic cylinder and tensiometer, the pneumatic cylinder is installed to workstation top one side, is connected with the tensiometer on the piston rod of pneumatic cylinder, still including the guide rail, clamping component, locking mechanical system and circular telegram subassembly, the workstation top is connected with the guide rail, is equipped with the clamping component who is used for pressing from both sides tight cable core and the locking mechanical system of locking clamping component after the cable core breaks on the guide rail, is equipped with circular telegram subassembly between clamping component and the guide rail.

As the improvement of the scheme, two guide tracks are arranged on the guide rail, wherein one guide track is slightly short and arranged on one side of the guide rail far away from the hydraulic cylinder, and the other guide track is slightly long and arranged at the position of the guide rail close to the hydraulic cylinder.

The improvement as above-mentioned scheme, clamping component is including the sliding block, two-way screw rod, anchor clamps and conducting strip, equal slidingtype is provided with the sliding block in the twice guide track, can dismantle through the bolt between the sliding block that is close to the tensiometer and link to each other, the equal rotary type in one side that the sliding block of both sides is close to each other is connected with two-way screw rod, two-way screw rod both sides all have anchor clamps through threaded connection, anchor clamps and sliding block sliding connection, one side that the anchor clamps of both sides are close to each other all is connected with the conducting strip, anchor clamps are when cliping the cable core, conducting strip and the contact of cable core on the sliding block of both sides, conducting strip on the sliding block of both sides can the electric property link to each other this moment, the conducting strip that is close to the pneumatic cylinder passes through electric connection with the pneumatic cylinder.

As the improvement of above-mentioned scheme, circular telegram subassembly is connected with the circular telegram piece that removes including removing circular telegram piece and fixed circular telegram piece on keeping away from the sliding block of pneumatic cylinder, is provided with fixed circular telegram piece in the slightly short guide rail on the guide rail, removes circular telegram piece and passes through electric connection with the conducting strip of keeping away from pneumatic cylinder department, removes the circular telegram piece and removes can and fix the circular telegram piece contact for the conducting strip of keeping away from pneumatic cylinder department is circular telegram.

As the improvement of above-mentioned scheme, locking mechanical system is including the locking uide bushing, the electro-magnet, the locking piece, the hoop, elastic component and ratchet locking strip, sliding block one side that is close to the pneumatic cylinder is connected with the locking uide bushing, the locking uide bushing bottom is connected with the electro-magnet, slidingtype connection has the locking piece in the locking uide bushing, be connected with the elastic component between locking piece and the locking uide bushing, be connected with the hoop on the locking piece, pass through electric connection between electro-magnet and the conducting strip that is close to the pneumatic cylinder, when removal circular telegram piece and fixed circular telegram piece contact and anchor clamps clip the cable core, can give the electro-magnet circular telegram, the electro-magnet circular telegram can adsorb the hoop and shift up, be used for driving the locking piece to shift up, one side that the ratchet guide rail is close to the locking piece is connected with the locking strip, the locking piece moves down and can block in ratchet locking strip, be used for the sliding block that will be connected with the locking uide bushing is fixed.

As the improvement of the scheme, the cable guide device further comprises a guide assembly, wherein the guide assembly comprises a connecting frame and a cable core guide sleeve, the top of the guide rail is connected with the connecting frame, and the lower part of one side of the connecting frame is connected with the cable core guide sleeve for guiding the cable core.

As the improvement of above-mentioned scheme, still including measuring mechanism, measuring mechanism is including movable block, scale, measuring block and locking bolt, and the sliding type is connected with the movable block on the link, and the movable block is connected with the scale towards one side of pneumatic cylinder, and the scale is located the link top, and the sliding block top that is close to the pneumatic cylinder is connected with the measuring block, and measuring block and link sliding fit, the sliding block can drive the measuring block and slide in the scale outside, has locking bolt through threaded connection on the movable block.

As the improvement of above-mentioned scheme, still including the protection against electric shock subassembly, the protection against electric shock subassembly is including hiding the framework, gear and rack, the sliding block top rotary type of keeping away from the pneumatic cylinder is connected with and hides the framework, it is hard insulating material to hide the framework, it is connected with the gear on the transmission shaft of hiding the framework, the position that the guide rail top is close to the gear is connected with the rack, it can drive the gear rotation to hide when the framework is rotatory, the gear rotation can be through rack removal, be used for driving and the slider that hides the framework links to each other removes.

1. When the device is operated, the circuit can be supplied through the cable core, and when the cable core is broken, the circuit can be stopped from being communicated, so that the electromagnet and the hydraulic cylinder can stop running, the phenomenon that the clamp continues to drive the cable core to move to influence the detection of the tensile length of the cable core is avoided, and the judgment of the tensile value of the cable core can also be ensured.

2. When the device is operated, the electromagnet and the hydraulic cylinder can be ensured to stop running after the cable core is broken through simple circuit communication, so that the accuracy of the tension value test of the cable core is ensured, the device is not required to be realized through a plurality of complex electric control devices, the cost is lower during production and manufacturing, and the failure rate can be reduced through a simple structure.

3. According to the invention, through the arrangement of the electric shock prevention assembly, when the conducting strip is in a power-on state, the covering frame body can cover the sliding block connected with the conducting strip, so that the conducting strip is covered, and when the conducting strip is not in the power-on state, the conducting strip can be exposed, so that the conducting strip is prevented from being touched by mistake when being powered on, and the safety is improved.

Drawings

Fig. 1 is a schematic perspective view of the present invention.

FIG. 2 is a schematic perspective view of the present invention showing the components of the table, the guide rail, the hydraulic cylinder, etc.

Fig. 3 is a schematic view of the connection relationship between the clamping assembly and other components.

Fig. 4 is a schematic perspective view of the jig and the conductive sheet of the present invention.

Fig. 5 is a schematic perspective view of the tension meter of the present invention.

FIG. 6 is a schematic view of the clamp assembly and locking mechanism of the present invention in connection with other components.

FIG. 7 is a partial cross-sectional view of the locking mechanism of the present invention.

Fig. 8 is a schematic view of the connection relationship between the guide assembly and other components of the present invention.

Fig. 9 is a schematic view of the connection relationship between the measuring mechanism and other components.

Fig. 10 is a schematic perspective view of the measuring mechanism and the connecting frame of the present invention.

Fig. 11 is a schematic view of the connection relationship between the anti-electric shock assembly and other components.

Number designation in the figures: 1. the measuring device comprises a workbench, 2, a guide rail, 3, a hydraulic cylinder, 31, a tension meter, 4, a clamping assembly, 41, a sliding block, 42, a bidirectional screw rod, 43, a clamp, 431, a conducting strip, 44, an electrifying assembly, 441, a movable electrifying strip, 442, a fixed electrifying strip, 5, a locking mechanism, 51, a locking guide sleeve, 511, an electromagnet, 52, a locking block, 521, an iron ring, 53, an elastic piece, 54, a ratchet locking strip, 6, a guide assembly, 61, a connecting frame, 62, a wire core guide sleeve, 7, a measuring mechanism, 71, a moving block, 711, a scale, 72, a measuring block, 73, a locking bolt, 8, an electric shock preventing assembly, 81, a covering frame body, 82, a rack, 83 and a gear.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The utility model provides a fire prevention cable core tensile test device, as shown in fig. 1-5, including workstation 1, guide rail 2, pneumatic cylinder 3, tensiometer 31, clamping component 4, locking mechanical system 5 and

circular telegram subassembly

44, 1 top of workstation is connected with guide rail 2, pneumatic cylinder 3 is installed on 1 right side of workstation, be connected with tensiometer 31 on pneumatic cylinder 3's the piston rod, be equipped with the locking mechanical system 5 that is used for clamping cable core's clamping component 4 and cable core stretch out back locking clamping component 4 on the guide rail 2, be equipped with circular telegram subassembly 44 between clamping component 4 and the guide rail 2, be provided with two length guide rails on the guide rail 2, short guide rail sets up in guide rail 2 left side, long guide rail sets up on guide rail 2 right side.

As shown in fig. 3, fig. 4 and fig. 6, the clamping assembly 4 includes a sliding block 41, a bidirectional screw 42, a fixture 43 and a conducting strip 431, the sliding block 41 is disposed in two guide tracks in a sliding manner, the right sliding block 41 and the tension meter 31 are detachably connected through a bolt, the two sliding blocks 41 on two sides are connected with the bidirectional screw 42 in a mutually close manner, the fixture 43 is connected with the sliding block 41 in a sliding manner through a thread on the front side and the rear side of the bidirectional screw 42, the conducting strip 431 is connected with one side of the two sliding blocks 43 in a mutually close manner, when the cable core is clamped by the fixture 43, the conducting strip 431 on the two sliding blocks 41 is in contact with the cable core, at this time, the conducting strip 431 on the two sliding blocks 41 can be electrically connected with the hydraulic cylinder 3, and the conducting strip 431 on the right side is electrically connected with the hydraulic cylinder 3.

As shown in fig. 3, the energizing unit 44 includes a movable energizing piece 441 and a fixed energizing piece 442, the movable energizing piece 441 is connected to the left slider 41, the fixed energizing piece 442 is provided in the left guide rail, the movable energizing piece 441 is electrically connected to the left conductive piece 431, and the movable energizing piece 441 can be moved to contact the fixed energizing piece 442 to energize the left conductive piece 431.

As shown in fig. 6 and 7, the locking mechanism 5 includes a locking guide sleeve 51, an electromagnet 511, a locking block 52, an iron ring 521, an elastic member 53 and a ratchet locking bar 54, the front side of the right slide block 41 is connected with the locking guide sleeve 51, the bottom of the locking guide sleeve 51 is connected with the electromagnet 511, the locking block 52 is connected in the locking guide sleeve 51 in a sliding manner, the elastic member 53 is connected between the locking block 52 and the locking guide sleeve 51, the iron ring 521 is connected to the locking block 52, the electromagnet 511 is electrically connected to the right conductive sheet 431, the movable conductive sheet 441 is in contact with the fixed conductive sheet 442, and when the clamp 43 clamps the cable core, the electromagnet 511 can be energized, the electromagnet 511 can attract the iron ring 521 to move upwards to drive the locking block 52 to move upwards, the ratchet locking bar 54 is connected to the front side of the guide rail 2, and the locking block 52 can move downwards to be clamped in the ratchet locking bar 54 to fix the slide block 41 connected with the locking guide sleeve 51.

When the tension test is needed to be carried out on the core of the fireproof cable, the device can be used, when in use, the bolt between the right side sliding block 41 and the tension meter 31 is detached, the right side sliding block 41 is pulled to move leftwards, when the right side sliding block 41 moves leftwards, the locking block 52 can repeatedly move upwards and downwards along the ratchet locking strip 54, the elastic piece 53 is used for resetting the locking block 52 until the distance between the two side sliding blocks 41 is close to the length of the cable core, then the right side sliding block 41 can be stopped to move, the locking block 52 can move downwards to be clamped at the ratchet locking strip 54 to lock the right side sliding block 41, then the bidirectional screws 42 at two sides are twisted to drive the clamps 43 at two sides to be far away from each other, then the two ends of the cable core are respectively placed between the front and rear clamps 43 at the left and right sides, after the placement is finished, the bidirectional screws 42 at two sides are reversely twisted to drive the clamps 43 at two sides to be close to each other, clamping a cable core, wherein the conducting strips 431 on the left side and the right side are electrically connected through the cable core, the conducting strip 431 on the right side is also electrically connected with the hydraulic cylinder 3, and then the left sliding block 41 can be pulled to move rightwards, so that the movable electrified strip 441 is contacted with the fixed electrified strip 442, thereby electrifying the hydraulic cylinder 3 and the electromagnet 511, the electromagnet 511 can adsorb an iron ring 521 to move upwards after being electrified, thereby driving the locking block 52 to move upwards and not to be locked by the ratchet locking strip 54, the elastic piece 53 is compressed, then the piston rod of the hydraulic cylinder 3 can be controlled to extend to drive the tension meter 31 to move until the tension meter 31 is close to the sliding block 41 on the right side, then the tension meter 31 and the right sliding block 41 are fixed through a bolt, then the piston rod of the hydraulic cylinder 3 is controlled to retract to drive the right sliding block 41 to move rightwards through the tension meter 31, thereby pulling the cable core, carry out the tension test to the cable core, the numerical value of tension test can show on tensiometer 31, when the cable core stretches out, left and right sides conducting strip 431 circuit no longer communicates with each other, pneumatic cylinder 3 outage no longer moves simultaneously, the piston rod of pneumatic cylinder 3 no longer moves, electro-magnet 511 also cuts off the power supply, locking piece 52 moves down the card on ratchet locking strip 54 under elastic component 53's effect, thereby it is fixed with sliding block 41 on right side, avoid the sliding block 41 displacement on right side, can judge tensile numerical value through tensiometer 31 this moment, so, just can carry out the tension test to the cable core, and after the cable core stretches out, can make right side sliding block 41 no longer move, avoid the detection of influence to cable core tensile length, also can guarantee the judgement to cable core tension value.

Example 2

On the basis of embodiment 1, as shown in fig. 1 and 8, the cable guide rail further comprises a guide assembly 6, wherein the guide assembly 6 comprises a connecting frame 61 and a cable core guide sleeve 62, the connecting frame 61 is connected to the right side of the top of the guide rail 2, and the cable core guide sleeve 62 is connected to the lower portion of the left side of the connecting frame 61 and used for guiding the cable cores.

The cable core can pass through the core guide sleeve 62 when testing, leads the cable core through the core guide sleeve 62.

As shown in fig. 1, 9 and 10, the measuring device 7 further comprises a measuring mechanism 7, the measuring mechanism 7 comprises a moving block 71, a graduated scale 711, a measuring block 72 and a locking bolt 73, the moving block 71 is connected to the connecting frame 61 in a sliding manner, the graduated scale 711 is connected to the right side of the moving block 71, the graduated scale 711 is located at the top of the connecting frame 61, the measuring block 72 is connected to the top of the right sliding block 41, the measuring block 72 is in sliding fit with the connecting frame 61, the sliding block 41 can drive the measuring block 72 to slide outside the graduated scale 711, and the locking bolt 73 is connected to the moving block 71 through a thread.

When the sliding block 41 is pulled to move leftwards, the sliding block 41 can drive the measuring block 72 to move leftwards when moving leftwards, the measuring block 72 can push the moving block 71 and the graduated scale 711 to move leftwards when moving leftwards, when the sliding block 41 moves to a proper position, the moving block 71 is fixed by twisting the locking bolt 73, then, a tension test can be performed, in the process of pulling the test, the sliding block 41 on the right side can move rightwards, the sliding block 41 can move rightwards when moving rightwards to drive the measuring block 72 to move rightwards, when a cable core is stretched and broken, the sliding block 41 on the right side and the measuring block 72 can not move any more, then, the position of the graduated scale 711 can be aligned according to the measuring block 72, the tensile elongation of the cable core can be measured, and the tensile length of the cable core can be conveniently judged.

As shown in fig. 1 and 11, the electric shock protection device further includes an electric shock protection assembly 8, the electric shock protection assembly 8 includes a cover frame 81, a gear 83 and a rack 82, the cover frame 81 is rotatably connected to the top of the left sliding block 41, the cover frame 81 is made of a hard insulating material, the gear 83 is connected to the front side of the transmission shaft of the cover frame 81, the rack 82 is connected to the front left side of the top of the guide rail 2, the cover frame 81 can drive the gear 83 to rotate when rotating, and the gear 83 can move through the rack 82 to drive the sliding block 41 connected to the cover frame 81 to move.

When the left slide block 41 is pulled to move rightwards, the covering frame 81 moves together, the gear 83 is driven to move when the covering frame 81 moves, the gear 83 rotates through the rack 82 in the moving process to drive the covering frame 81 to rotate, when the moving conducting piece 441 is moved to be in contact with the fixed conducting piece 442 to conduct electricity, the covering frame 81 covers the left slide block 41, so that when the moving conducting piece 441 is in contact with the fixed conducting piece 442 to conduct electricity, a person mistakenly touches parts on the left slide block 41 to cause electric shock, safety in operation can be improved, when the moving conducting piece 441 is separated from the fixed conducting piece 442 by pulling the left slide block 41 to move leftwards, the covering frame 81 is reversely rotated and opened through the gear 83 and the rack 82, and therefore, when the moving conducting piece 441 is in contact with the fixed conducting piece 442 to conduct electricity, the left slide block 41 is covered to prevent the person from mistakenly touching to cause electric shock, and safety in operation is improved.

The above-mentioned embodiments are only preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, so that all equivalent changes made by the contents of the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A fireproof cable core tensile test device comprises a workbench (1), a hydraulic cylinder (3) and a tension meter (31), wherein the hydraulic cylinder (3) is installed on one side of the top of the workbench (1), the tension meter (31) is connected onto a piston rod of the hydraulic cylinder (3), the fireproof cable core tensile test device is characterized by further comprising a guide rail (2), a clamping component (4), a locking mechanism (5) and an electrifying component (44), the guide rail (2) is connected to the top of the workbench (1), the clamping component (4) for clamping a cable core and the locking mechanism (5) for locking the clamping component (4) after the cable core is tensioned, and the electrifying component (44) is arranged between the clamping component (4) and the guide rail (2); two guide rails are arranged on the guide rail (2), wherein one guide rail is slightly short and arranged on one side of the guide rail (2) far away from the hydraulic cylinder (3), and the other guide rail is slightly long and arranged at the position of the guide rail (2) close to the hydraulic cylinder (3); the clamping assembly (4) comprises sliding blocks (41), two-way screw rods (42), clamps (43) and conducting strips (431), the sliding blocks (41) are arranged in two guide tracks in a sliding mode, the sliding blocks (41) close to the tension meters (31) are detachably connected with the tension meters (31) through bolts, the two-way screw rods (42) are rotatably connected to one sides of the sliding blocks (41) at two sides close to each other, the clamps (43) are connected to two sides of the two-way screw rods (42) through threads, the clamps (43) are slidably connected with the sliding blocks (41), the conducting strips (431) are connected to one sides of the clamps (43) at two sides close to each other, when the clamps (43) clamp cable cores, the conducting strips (431) on the sliding blocks (41) at two sides are in contact with the cable cores, the conducting strips (431) on the sliding blocks (41) at two sides can be electrically connected at the moment, and the conducting strips (431) close to the hydraulic cylinders (3) are electrically connected with the hydraulic cylinders (3); the electrifying assembly (44) comprises a movable electrifying piece (441) and a fixed electrifying piece (442), the sliding block (41) far away from the hydraulic cylinder (3) is connected with the movable electrifying piece (441), the guide rail (2) is provided with the fixed electrifying piece (442) in a slightly short guide track, the movable electrifying piece (441) is electrically connected with the conducting piece (431) far away from the hydraulic cylinder (3), and the movable electrifying piece (441) can be in contact with the fixed electrifying piece (442) in a moving manner and is used for electrifying the conducting piece (431) far away from the hydraulic cylinder (3); the locking mechanism (5) comprises a locking guide sleeve (51), an electromagnet (511), a locking block (52), an iron ring (521), an elastic piece (53) and a ratchet locking strip (54), one side of a sliding block (41) close to the hydraulic cylinder (3) is connected with the locking guide sleeve (51), the bottom of the locking guide sleeve (51) is connected with the electromagnet (511), the locking guide sleeve (51) is internally connected with the locking block (52) in a sliding manner, the elastic piece (53) is connected between the locking block (52) and the locking guide sleeve (51), the iron ring (521) is connected onto the locking block (52), the electromagnet (511) is electrically connected with a conducting strip (431) close to the hydraulic cylinder (3) through electric connection, a movable conducting piece (441) is in contact with a fixed conducting piece (442), and a clamp (43) clamps a cable core, the electromagnet (511) can be powered on, the electromagnet (511) can adsorb the iron ring (521) to move upwards to drive the locking block (52), one side of the guide rail (2) close to the locking block (52) is connected with the locking strip (54), the ratchet can be clamped in the locking block (52) to move downwards, and the sliding block (51) is used for fixing the sliding block (41).

2. The tensile test device for the core of the fireproof cable according to claim 1, further comprising a guiding assembly (6), wherein the guiding assembly (6) comprises a connecting frame (61) and a core guiding sleeve (62), the connecting frame (61) is connected to the top of the guide rail (2), and the core guiding sleeve (62) is connected to the lower portion of one side of the connecting frame (61) and used for guiding the core of the cable.

3. The fireproof cable core tensile test device according to claim 2, further comprising a measuring mechanism (7), wherein the measuring mechanism (7) comprises a moving block (71), a graduated scale (711), a measuring block (72) and a locking bolt (73), the moving block (71) is connected to the connecting frame (61) in a sliding manner, the graduated scale (711) is connected to one side, facing the hydraulic cylinder (3), of the moving block (71), the graduated scale (711) is located at the top of the connecting frame (61), the measuring block (72) is connected to the top of the sliding block (41) close to the hydraulic cylinder (3), the measuring block (72) is in sliding fit with the connecting frame (61), the sliding block (41) can drive the measuring block (72) to slide outside the graduated scale (711), and the locking bolt (73) is connected to the moving block (71) through a thread.

4. The tensile test device for the core of the fireproof cable according to claim 1, further comprising an electric shock prevention assembly (8), wherein the electric shock prevention assembly (8) comprises a covering frame (81), a gear (83) and a rack (82), the top of the sliding block (41) far away from the hydraulic cylinder (3) is rotatably connected with the covering frame (81), the covering frame (81) is made of a hard insulating material, the gear (83) is connected to a transmission shaft of the covering frame (81), the rack (82) is connected to a position, close to the gear (83), of the top of the guide rail (2), the gear (83) can be driven to rotate when the covering frame (81) rotates, and the gear (83) can rotate and move through the rack (82) so as to drive the sliding block (41) connected with the covering frame (81) to move.