Optical path module of full-automatic cutting machine
By adopting the optical path module of the fully automatic cutting machine in the laser cutter and using the sealing design of the optical path seal cover and reflector, the problem of the lack of sealing protection of the optical path of the existing laser cutter is solved, and the optical path sealing and operation safety are improved. Adapt to the movement of the field mirror.
Patent Information
- Application Number
- CN202421170962.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-27
- Publication Date
- 2025-02-25
- Estimated Expiration
- 2034-05-27
AI Technical Summary
The open optical path of existing laser cutters lacks sealing protection and is easily disturbed by environmental interference, resulting in laser beam polarization, spot loss and reflection angle changes, and there are safety hazards, which cannot ensure the safety of operators.
The optical path module of the fully automatic cutting machine is used to isolate the laser from the outside through the optical path sealing cover. The first and second outer covers are used to seal the mirror to keep the mirror clean, and the mirror surface is clean and pass through the slot, clamp strip and roller. The optical path seal cover has elasticity and adapts to the movement of the field mirror.
It improves the sealing of the optical path, prevents the external environment from affecting the laser beam, ensures the safety of the operator, and keeps the mirror clean and adapts to the movement of the field mirror without hindering it.
Smart Images
Figure CN222520246U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of laser cutting optical paths, and in particular relates to an optical path module of a full-automatic cutting machine. Background Art
[0002] Laser cutting is a laser processing technology that uses the energy released when the laser beam is irradiated onto the surface of the workpiece to melt and evaporate the workpiece. It can achieve the purpose of cutting and engraving, and has the characteristics of high precision, fast cutting, no restrictions on cutting patterns, automatic typesetting to save materials, smooth incisions, and low processing costs. The structure for guiding, focusing and irradiating the laser can be collectively referred to as the optical path. The optical path refers to the propagation path of light, including the route after refraction and reflection during light propagation.
[0003] In the prior art, laser cutters usually use an open optical path, that is, the laser emitted from the laser generator directly passes through multiple sets of reflectors to the product processing site, without any sealing protection during the process. This method is easily affected by dust, microorganisms, etc. in the environment, which may cause problems such as laser beam polarization, spot loss and reflection angle change. Water vapor and fog may also cause the lens to fog, thereby weakening the laser energy and causing spot deformation. At the same time, since the laser light source itself is invisible, if it is accidentally irradiated on human skin or eyes, it may cause burns or burns, posing a safety hazard and failing to ensure the safety of operators. Utility Model Content
[0004] In view of this, the utility model provides an optical path module for a fully automatic cutting machine, the purpose of which is to isolate the laser from the outside world through an optical path sealing cover to prevent the external environment from affecting the laser beam and the laser beam from affecting personnel. At the same time, the first reflective cover and the second reflective cover can also play the role of sealing the reflector, which helps to keep the mirror surface clean.
[0005] The technical solution adopted by the utility model is as follows:
[0006] A fully automatic cutting machine optical path module comprises a cutting table, a laser generator and a first reflective cover fixed on the top of the cutting table, and a second reflective cover located in the same horizontal direction as the first reflective cover, wherein the laser generator is vertically distributed with the first reflective cover, and a light emitting port is provided on the side of the laser generator facing the first reflective cover, and the first reflective cover and the second reflective cover are both provided with a light inlet and a light outlet located at different end faces, wherein an optical path sealing cover is connected between the first reflective cover and the second reflective cover, and the optical path sealing cover is sleeved on the light outlet of the first reflective cover and the light inlet of the second reflective cover.
[0007] As a preferred technical solution, the optical path sealing cover is a spliced structure, including two first sealing plates and two second sealing plates, and the first sealing plate and the second sealing plate are both rectangular plates with a concave opening on one side surface.
[0008] Furthermore, the first sealing plate and the second sealing plate are both provided with a splicing interface on one side with a concave opening, and an embedding opening and a clamping strip are provided in the opening of the second sealing plate, a clamping groove is provided on the side of the first sealing plate away from the opening, and the first sealing plate is movably embedded in the embedding opening by clamping the clamping strip through the clamping groove.
[0009] Furthermore, a plurality of rollers are provided inside the card strip on a side facing the card slot.
[0010] Furthermore, two longitudinal grooves are provided on the top surface of the cutting table, and the two longitudinal grooves are distributed in parallel on the side of a reverse cover facing the laser generator, a Y axis is passed through the longitudinal groove, and an X axis is transversely fixed on the top of the Y axis, and the two reverse covers are fixed on the end face of the connection between the X axis and the Y axis.
[0011] Furthermore, a translation assembly, a galvanometer and a field lens are provided on the shaft body of the X-axis, wherein the galvanometer is parallel to the light outlet on the second reflector outer cover, and the field lens is vertically fixed below the galvanometer, and the translation assembly includes a guide rail distributed along the X-axis, a ball embedded in the guide rail and a transmission block, the transmission block is fitted with the ball, and the galvanometer is movably connected to the guide rail through the transmission block.
[0012] Furthermore, the top openings of the first and second reverse outer covers are both provided with sealing top covers, and any two parallel inner walls where the openings fit the sealing top covers are both provided with fixing openings, and a plug plate is provided on one side of the sealing top cover facing the fixing opening.
[0013] Furthermore, the sealing top cover is provided with an empty interlayer on one side of the plug plate, and the plug plate is clamped in the empty interlayer, a connecting column is fixed to one end of the plug plate facing the empty interlayer, and a paddle is fixed to the other end of the connecting column, and a compression spring is provided on the side of the paddle away from the connecting column.
[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the utility model are:
[0015] 1. The optical path sealing cover is used to isolate the laser from the outside world to prevent the external environment from affecting the laser beam and the laser beam from affecting personnel. At the same time, the first and second reflective covers can also seal the reflector, which helps to keep the reflector surface clean.
[0016] 2. Through the arrangement of the card slot, the card strip and the roller, the optical path sealing cover is made retractable and can adapt to the movement of the field lens without hindering the movement of the field lens. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The present invention will be described by way of examples with reference to the accompanying drawings, in which:
[0018] Figure 1This is a structural schematic diagram of an optical path module of a fully automatic cutting machine provided by the utility model;
[0019] Figure 2 It is a structural schematic diagram of the optical path sealing cover provided by the utility model;
[0020] Figure 3 It is a structural schematic diagram of a reverse outer cover provided by the utility model;
[0021] Figure 4 It is a schematic diagram of the structure of the second anti-cover provided by the utility model;
[0022] Figure 5 It is a structural schematic diagram of the sealing top cover provided by the utility model.
[0023] Cutting table-1; laser generator-2; first reflector cover-3; sealing top cover-4; second reflector cover-5; galvanometer-6; field lens-7; optical path sealing cover-8; light emission port-9; light inlet-10; longitudinal groove-11; X-axis-12; Y-axis-13; translation assembly-14; first sealing plate-15; second sealing plate-16; card slot-17; splicing port-18; embedding port-19; card strip-20; roller-21; fixing port-22; light outlet-23; plug-in board-24; empty interlayer-25; plectrum-26; connecting column-27; compression spring-28. DETAILED DESCRIPTION
[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.
[0025] Embodiment 1
[0026] In the prior art, laser cutters usually use an open optical path, that is, the laser is emitted directly from the laser generator and reaches the product processing site through multiple sets of reflectors, and there is no sealing protection in the whole process. This practice is easily interfered by dust, microorganisms, etc. in the environment, which may cause problems such as laser beam polarization, spot loss, and reflection angle changes. Water vapor and fog can also cause lens fogging, weaken laser energy and cause spot deformation. In addition, since the laser light source itself is invisible, once it is accidentally irradiated on human skin or eyes, it may cause burns or burns, posing a safety hazard and failing to ensure the safety of the operator.
[0027] Therefore, in order to solve the problem that the existing laser optical path lacks sealing protection during the reflection process, is greatly affected by environmental interference, and causes damage to the operator, and to achieve the function of improving the sealing of the optical path and ensuring the safety of the operator, the utility model discloses an optical path module for a fully automatic cutting machine, see Figure 1-Figure 2 , comprising a cutting table 1, a laser generator 2 and a first reflective cover 3 fixed on the top of the cutting table 1, and a second reflective cover 5 located in the same horizontal direction as the first reflective cover 3, the laser generator 2 is vertically distributed with the first reflective cover 3, and the laser generator 2 is provided with a light emitting port 9 on the side facing the first reflective cover 3, the first reflective cover 3 and the second reflective cover 5 are both provided with a light inlet 10 and a light outlet 23 located on different end faces, wherein an optical path sealing cover 8 is connected between the first reflective cover 3 and the second reflective cover 5, and the optical path sealing cover 8 is sleeved on the light outlet 23 of the first reflective cover 3 and the light inlet 10 of the second reflective cover 5.
[0028] In this embodiment, the light inlet 10 and the light outlet 9 provided on the first reflective cover 3 are parallel to each other, and the light outlet 23 provided on the first reflective cover 3 and the light inlet 10 provided on the second reflective cover 5 are parallel to each other.
[0029] In this embodiment, a reflector is disposed inside the first reflective cover 3 or the second reflective cover 5 , and in an initial state, the reflector and the light inlet 10 on the corresponding cover are inclined at 45 degrees.
[0030] In the present embodiment, preferably, the optical path sealing cover 8 is a detachable structure, including that the optical path sealing cover 8 is a spliced structure, including two first sealing plates 15 and two second sealing plates 16, and the first sealing plates 15 and the second sealing plates 16 are both rectangular plates with a concave opening on one side surface, so that the operator can connect the two first sealing plates 15 and the two second sealing plates 16 with each other along the concave opening to close the opening.
[0031] In this embodiment, the light path sealing cover 8 is provided as a detachable structure, so that the operator will not be blocked by the light path sealing cover 8 when adjusting the light path guide.
[0032] In this embodiment, the first sealing plate 15 and the second sealing plate 16 are fixed to the first and second reverse outer covers 3 and 5 by screws. This arrangement makes it difficult for the light path sealing cover 8 to disintegrate naturally, thereby improving the stability of the light path sealing cover 8.
[0033] In this embodiment, optionally, a magnet sheet may be provided on the surface of the splicing interface 18 .
[0034] During use: When splicing the optical path sealing cover 8, the operator can first align the card slot 17 on the first sealing plate 15 with the card strip 20 in the embedding port 19 of the second sealing plate 16. The operator can first push the first sealing plate 15 into the second sealing plate 16 along the embedding port 19 on the second sealing plate 16, and then splice the two pairs of embedded first sealing plates 15 and second sealing plates 16 together along the splicing port 18 to form the optical path sealing cover 8 as a whole, and then fix the two openings of the optical path sealing cover 8 on the light outlet 10 of the first anti-outer cover 3 and the light inlet 10 of the second anti-outer cover 5 by screws, and isolate the laser from the outside world through the optical path sealing cover 8 to prevent the external environment from affecting the laser beam and the laser beam from affecting personnel. At the same time, the first anti-outer cover 3 and the second anti-outer cover 5 can also play the role of sealing the reflector, which helps to keep the mirror surface of the reflector clean. At the same time, by inserting the card strip 20 into the card slot 17, the first sealing plate 15 is not easy to loosen in the second sealing plate 16.
[0035] Working principle: The laser generator 2 is a laser light source. The laser beam is emitted through the light outlet 9 to the light inlet 10 of the first reflective cover 3. Then, the reflector in the first reflective cover 3 refracts the light beam, so that the light beam is emitted from the light outlet 23 of the first reflective cover 3 to the light inlet 10 of the second reflective cover 5. Then, the reflector in the second reflective cover 5 can refract the laser beam again and emit it through the light outlet 23 on the second reflective cover 5. At the same time, when the light beam is refracted from the first reflective cover 3 and the second reflective cover 5, it is wrapped in the inside of the optical path sealing cover 8.
[0036] Embodiment 2
[0037] See also Figure 1 On the basis of the first embodiment, it further includes an X-axis 12 and a Y-axis 13 for controlling the direction of the laser landing point. Specifically, two longitudinal grooves 11 are opened on the top surface of the cutting table 1, and the two longitudinal grooves 11 are parallelly distributed on the side of the first anti-cover 3 facing the laser generator 2. The Y-axis 13 is passed through the interior of the longitudinal groove 11, and the top of the Y-axis 13 is transversely fixed with the X-axis 12, and the second anti-cover 5 is fixed on the end face of the X-axis 12 facing the first anti-cover 3.
[0038] In this embodiment, a lead screw coaxial with the longitudinal groove 11 is provided inside the longitudinal groove 11 , and the lead screw passes through a Y-axis 13 located at the bottom of one side of the longitudinal groove 11 .
[0039] In this embodiment, preferably, a translation assembly 14, a galvanometer 6 and a field lens 7 are provided on the shaft body of the X-axis 12, wherein the galvanometer 6 is parallel to the light outlet 23 on the second reflector cover 5, and the field lens 7 is vertically fixed below the galvanometer 6, and the translation assembly 14 includes a guide rail distributed along the X-axis 12, a ball embedded in the guide rail and a transmission block, the transmission block is fitted with the ball, and the galvanometer 6 is movably connected to the guide rail through the transmission block, wherein the guide rail is concave in shape, and a plurality of ball bearings are embedded in the upper and lower inner walls of the guide rail groove opening, and the upper and lower ends of the transmission block are fitted with the ball bearings, so that the transmission block is clamped in the groove of the guide rail.
[0040] In this embodiment, optionally, an optical path sealing cover 8 is connected between the second reflective cover 5 and the galvanometer 6 .
[0041] In this embodiment, the lead screw and the transmission block are controlled by a driving member in the cutting table 1, and the driving member can be a motor or a cylinder.
[0042] When in use: first start the cutting table 1 so that the Y-axis 13 can make repeated horizontal movements in the longitudinal groove 11, and at the same time the transmission block can drive the field lens 7 to make reciprocating movements along the X-axis 12, so that the field lens 7 can move the landing point of the laser to all corners of the top of the cutting table 1.
[0043] Working principle and use: When the laser beam is emitted from the light outlet 23 of the second reflector cover 5, the galvanometer 6 can receive the light beam and refract it into the field lens 7, and then the field lens 7 can focus the light beam and drop it onto the workpiece of the cutting table 1 for cutting. When the cutting table 1 is started, the lead screw can rotate and drive the Y-axis 13, so that the field lens 7 fixed on the X-axis 12 can move horizontally along the longitudinal groove 11, and then the transmission block can move inside the guide rail to drive the field lens 7 to reciprocate along the X-axis 12. At the same time, the ball can reduce the sliding friction of the transmission block and reduce the shaking of the field lens 7 when it moves.
[0044] Embodiment 3
[0045] When the field lens 7 on the Y-axis 13 or the X-axis 12 is displaced, the spacing between the first reflector cover 3, the second reflector cover 5 and the galvanometer 6 will change. Since the optical path sealing cover 8 is fixedly connected between the first reflector cover 3, the second reflector cover 5 and the galvanometer 6, the displacement of the field lens 7 will be affected. In order to solve the above problem and improve the adaptability of the optical path sealing cover 8, refer to Figure 1-Figure 2On the basis of the first and second embodiments, the embodiment further includes a card slot 17, a card strip 23 and a roller 21. Specifically, the first sealing plate 15 and the second sealing plate 16 are provided with a splicing interface 18 on one side with a concave opening, and the second sealing plate 16 is provided with an embedding port 19 and a card strip 20 on one side with the splicing interface 18. The first sealing plate 15 is provided with a card slot 17 on one side away from the splicing interface 18, and the first sealing plate 15 is provided with a side with the card slot 17 movably embedded in the embedding port 19, and the card slot 17 is movably clamped on the card strip 20, and a plurality of rollers 21 are provided on the inner side of the card strip 20, and the rollers 21 are fitted with the first sealing plate 15.
[0046] In this embodiment, the width of the first sealing plate 15 is smaller than that of the second sealing plate 16 , and the lengths of the first sealing plate 15 and the second sealing plate 16 are equal.
[0047] During use: when the second reflector cover 5 moves due to the Y-axis 13 or the galvanometer 6 moves due to the transmission block, the first sealing plate 15 will reciprocate in the second sealing plate 16 along the moving direction of the second reflector cover 5 or the galvanometer 6. For example, when the second reflector cover 5 is close to the first reflector cover 3, the first sealing plate 15 will be pushed into the second sealing plate 16 along the moving direction of the second reflector cover 5. Conversely, the first sealing plate 15 can be pulled out from the second sealing plate 16. Through the above structure, the optical path sealing cover 8 can adapt to the movement of the field lens 7 without hindering the movement of the field lens 7.
[0048] Working principle: when the Y-axis 13 reciprocates in the longitudinal groove 11, it will simultaneously drive the X-axis 12, the second reflector outer cover 5 and the field lens 7, so that the second reflector outer cover 5 will approach or move away from the first reflector outer cover 3. Since the first sealing plate 15 is fixed on the second reflector outer cover 5, the approach or distance of the second reflector outer cover 5 will apply a thrust or pull force to the first sealing plate 15. Similarly, when the field lens 7 reciprocates on the X-axis 12, the galvanometer 6 will approach or move away from the second reflector outer cover 5, so that the first sealing plate 15 fixed on the other side of the second reflector outer cover 5 receives a push-pull force. Subsequently, when the first sealing plate 15 is subjected to a push-pull force, the first sealing plate 15 can slide in the embedding port 19 of the second sealing plate 16 through the roller 21. The roller 21 can reduce friction, so that the first sealing plate 15 is not prone to jamming during the extension and retraction process, while reducing wear.
[0049] Embodiment 4
[0050] See also Figure 3-Figure 5 On the basis of the first embodiment, it further includes a sealing top cover 4 for sealing the top of the first reverse outer cover 3 and the second reverse outer cover 5. Specifically, the top openings of the first reverse outer cover 3 and the second reverse outer cover 5 are both provided with a sealing top cover 4, and any two parallel inner walls where the openings and the sealing top cover 4 are in contact are provided with a fixing port 22, and the sealing top cover 4 is provided with a plug plate 24 on one side facing the fixing port 22.
[0051] In this embodiment, the top openings of the first and second reverse outer covers 3 and 5 and the sealing top cover 4 are all rectangular.
[0052] In this embodiment, when the sealing top cover 4 is sealed in the opening, the inserting plate 24 is inserted into the fixing opening 22 .
[0053] In the present embodiment, preferably, the sealing top cover 4 can be installed and disassembled without external tools. Specifically, the sealing top cover 4 is provided with an empty interlayer 25 on one side of the plug plate 24, and the plug plate 24 is movably clamped in the empty interlayer 25, and a connecting column 27 is fixed to one end of the plug plate 24 facing the empty interlayer 25, and a paddle 26 is fixed to one end of the connecting column 27 passing through the empty interlayer 25, and a compression spring 28 is provided on the side of the paddle 26 away from the connecting column 27, wherein the empty interlayer 25 is divided into two parts, a closed part and an open part, and the two parts are connected to each other, the plug plate 24 is clamped in the closed part, and the paddle 26 and the compression spring 28 are located in the open part, and the connecting column 27 is passed between the closed and open parts.
[0054] During use: when it is necessary to install the sealing top cover 4, the operator can push the paddle 26 toward one side of the compression spring 28 and continue to press the paddle 26, so that the plug plate 24 can be retracted into the empty interlayer 25, and then align the two ends of the sealing top cover 4 with the plug plate 24 with the fixing port 22, and then release the paddle 26, so that the plug plate 24 can pop out from the empty interlayer 25 and insert into the fixing port 22, and the installation is completed. Subsequently, when it is necessary to remove the sealing top cover 4, the operator only needs to repeat the above process, first continue to press the paddle 26 to retract the plug plate 24, and then release the paddle 26 after taking it out. Through the above structure, the operator can more conveniently adjust the angle and clean the reflectors in the first reflective cover 3 and the second reflective cover 5.
[0055] Working principle: When the operator moves the paddle 26 toward one side of the compression spring 28 and continues to press, the compression spring 28 can contract, so that the paddle 26 can drive the connecting column 27 to move toward the compression spring 28, thereby pulling the plug plate 24 fixedly connected to the connecting column 27 into the empty interlayer 25. When the operator releases the paddle 26, the compression spring 28 is reset, so that the connecting column 27 can push the plug plate 24 out of the empty interlayer 25 again.
[0056] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.
[0057] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. An optical path module of a fully automatic cutting machine, comprising a cutting table (1), a laser generator (2) and a first reflective cover (3) fixed on the top of the cutting table (1), and a second reflective cover (5) located in the same horizontal direction as the first reflective cover (3), characterized in that: The laser generator (2) is vertically distributed with the first reflective outer cover (3), and a light emitting port (9) is provided on the side of the laser generator (2) facing the first reflective outer cover (3). The first reflective outer cover (3) and the second reflective outer cover (5) are both provided with a light inlet (10) and a light outlet (23) located at different end faces, wherein a light path sealing cover (8) is connected between the first reflective outer cover (3) and the second reflective outer cover (5), and the light path sealing cover (8) is sleeved on the light outlet (23) of the first reflective outer cover (3) and the light inlet (10) of the second reflective outer cover (5).
2. The optical path module of a fully automatic cutting machine according to claim 1, characterized in that: The optical path sealing cover (8) is a spliced structure, comprising two first sealing plates (15) and two second sealing plates (16); the first sealing plates (15) and the second sealing plates (16) are both rectangular plates with a concave opening on one side surface.
3. The optical path module of a fully automatic cutting machine according to claim 2, characterized in that: The first sealing plate (15) and the second sealing plate (16) are both provided with a splicing interface (18) on the side with the concave opening, and the second sealing plate (16) is provided with an embedding opening (19) and a clamping strip (20) in the opening, and the first sealing plate (15) is provided with a clamping groove (17) on the side away from the opening, and the first sealing plate (15) is movably embedded in the embedding opening (19) by clamping the clamping strip (20) through the clamping groove (17).
4. The optical path module of a fully automatic cutting machine according to claim 3, characterized in that: A plurality of rollers (21) are arranged inside the clamping strip (20) on the side facing the clamping slot (17).
5. The optical path module of a fully automatic cutting machine according to claim 1, characterized in that: The top surface of the cutting table (1) is provided with two longitudinal grooves (11), and the two longitudinal grooves (11) are parallelly distributed on the side of a reverse outer cover (3) facing the laser generator (2), a Y axis (13) is passed through the interior of the longitudinal groove (11), and an X axis (12) is transversely fixed on the top of the Y axis (13), and the second reverse outer cover (5) is fixed on the end surface of the connection between the X axis (12) and the Y axis (13).
6. The optical path module of a fully automatic cutting machine according to claim 5, characterized in that: The shaft of the X-axis (12) is provided with a translation assembly (14), a galvanometer (6) and a field lens (7), wherein the galvanometer (6) is parallel to the light outlet (23) on the second reflector cover (5), and the field lens (7) is vertically fixed below the galvanometer (6); the translation assembly (14) comprises a guide rail distributed along the X-axis (12), a ball bearing embedded in the guide rail and a transmission block, the transmission block is fitted with the ball bearing, and the galvanometer (6) is movably connected to the guide rail via the transmission block.
7. The optical path module of a fully automatic cutting machine according to claim 1, characterized in that: The top openings of the first reverse outer cover (3) and the second reverse outer cover (5) are both provided with a sealing top cover (4), and any two parallel inner walls where the openings are in contact with the sealing top cover (4) are both provided with a fixing opening (22), and a plug plate (24) is provided on one side of the sealing top cover (4) facing the fixing opening (22).
8. The optical path module of a fully automatic cutting machine according to claim 7, characterized in that: The sealing top cover (4) is provided with a hollow interlayer (25) on one side of the plug plate (24), and the plug plate (24) is sandwiched in the hollow interlayer (25). A connecting column (27) is fixed to one end of the plug plate (24) facing the hollow interlayer (25), and a paddle (26) is fixed to the other end of the connecting column (27), and a compression spring (28) is provided on the side of the paddle (26) away from the connecting column (27).