Cleanable gate valve

Abstract

The utility model belongs to the technical field of fluid valves, and particularly relates to a cleanable gate valve. The structure comprises a valve body frame, a base and an inserting plate, the valve body frame comprises a top wall, a bottom wall, a first side wall and a second side wall, the two ends of the top wall are connected with the upper ends of the first side wall and the second side wall respectively, and the two ends of the bottom wall are connected with the middle of the first side wall and the middle of the second side wall respectively; wherein the bottom wall is provided with a first strip-shaped hole, the inner wall of the first side wall and the inner wall of the second side wall are each provided with a first inserting groove, and the inserting plate extends into the first strip-shaped hole and is inserted into the first inserting grooves in a matched mode; in addition, the base is detachably connected with the lower ends of the first side wall and the second side wall, and a second inserting groove allowing the bottom end of the inserting plate to be inserted therein is formed in the base. According to the structure, the base of the gate valve can be conveniently detached, the sealing groove is formed in the detached base, solids or jelly deposited on the sealing groove can be conveniently cleaned, and the production efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of fluid valves, and in particular relates to a cleanable plug-in valve. Background Art

[0002] The gate valve, also known as the manual knife gate valve, is a commonly used industrial valve. Its structure mainly consists of a valve body, a valve plate, a valve stem and a drive device. In the closed state, the valve plate fits tightly against the valve body to form a seal; when opened, the valve stem drives the valve plate to rise, allowing the fluid to pass through the gap between the valve plate and the valve body. It is widely used in the opening, closing and flow control of various fluid pipelines.

[0003] However, in the application of the prior art, the cleaning problem of the gate valve often affects its application. For example, in the flue gas treatment system, the gate valve is used to control the flow of flue gas, which contains a large amount of dust and free water molecules. These dust and water are deposited in the pipes and valves, especially the dust is easy to form a blockage between the valve plate and the valve body, affecting the normal opening and closing of the valve, resulting in flue gas leakage. Secondly, the sealing performance of the gate valve is greatly affected by temperature, and temperature changes may cause sealing failure.

[0004] In glass kilns, the challenges faced by gate valves are even more severe. Boron trioxide dust in the flue gas of glass kilns has strong adhesion and is easily deposited on the inner wall and valve plate of the valve. At the same time, the free water molecules in the flue gas cool down on the inner wall of the valve to form liquid water, which reacts chemically with the deposited dust to produce colloidal substances such as sodium borate. These substances will not only block the valve, but also accumulate in the gap at the bottom of the valve, making it impossible to completely close the valve, causing flue gas leakage.

[0005] To solve this problem, a dust chamber design with one in use and one in reserve is usually adopted. When one set of chambers needs to be overhauled and the dust bag is replaced, the other set of chambers continues to be used, thus ensuring that one set of chambers is always in working condition. However, during the replacement of the chambers, the corresponding air inlet valve needs to be replaced. Due to the hazards of boron trioxide dust and liquid sodium borate in the flue gas, the gate valve will face serious challenges during use.

[0006] A self-cleaning and anti-clogging manual knife-type gate valve is disclosed in the prior art (application number 202022293943.1 and authorization announcement number CN 213419953 U). This gate valve timely blows away the accumulated materials on both sides of the manual gate valve to avoid the accumulated materials affecting the normal closing of the valve plate. Specifically, the structure is provided with a blowing hole on the inner side wall of the gate valve frame, and a small fan is connected to the outside of the gate valve frame. The fan delivers wind to the blowing hole through the ventilation duct, thereby effectively blowing away the materials on both sides of the gate valve frame. This design can ensure that materials will not accumulate on the inside of the gate valve frame, thereby achieving the effect of automatic cleaning. However, the above structure has some problems, such as small fans, ventilation ducts, air outlets, etc. all require a certain amount of space, which is inconvenient to use in some narrow or complex environments. In addition, the use of small fans in this structure may consume a certain degree of energy. In addition, the sealing performance of the gate valve is greatly affected by temperature, and temperature changes may cause sealing failure.

[0007] Therefore, in order to improve the reliability and stability of the gate valve in the glass furnace flue gas treatment system, it is necessary to develop a new type of gate valve that can adapt to the working environment of high temperature, high dust and high adhesion and has better sealing performance. Utility Model Content

[0008] A technical problem to be solved by the utility model is: how to make the plug valve in the smoke treatment system more convenient to clean.

[0009] In order to solve the above technical problems, on the one hand, the embodiment of the utility model provides a cleanable plug valve, including a valve body frame, a base and a plug plate, the valve body frame includes a top wall, a bottom wall, a first side wall and a second side wall, wherein the two ends of the top wall are respectively connected to the upper ends of the first side wall and the second side wall, and the two ends of the bottom wall are respectively connected to the middle parts of the first side wall and the second side wall;

[0010] The bottom wall is provided with a first strip hole, the inner walls of the first side wall and the second side wall are both provided with a first slot, the plug plate extends through the first strip hole and is adaptively inserted into the first slot;

[0011] In addition, the base is detachably connected to the lower ends of the first side wall and the second side wall, and a second slot for inserting the bottom end of the plug board is provided on the base.

[0012] In some embodiments, first screw holes are respectively provided at the lower ends of the first side wall and the second side wall, and two first through holes are provided on the base, and two first bolts pass through the two first through holes and are connected to the two first screw holes respectively.

[0013] In some embodiments, protrusions are respectively provided at the lower ends of the first side wall and the second side wall, and engaging pieces capable of engaging with the protrusions are respectively provided on the base, and the engaging pieces are engaged and connected with the protrusions.

[0014] In some embodiments, a sealing groove is also fixed to the inner wall of the base, and the sealing groove includes a U-shaped groove structure formed by a first groove body, a second groove body and a third groove body connected in sequence. The first groove body and the third groove body are fitably inserted in two first slots, and the second groove body is fitably inserted in the second slot. Both sides of the plug-in board are fitably inserted in the first groove body and the third groove body, and the bottom of the plug-in board can be fitably inserted in the second groove body.

[0015] In some embodiments, a flexible groove body, a pad and multiple elastic members are also provided in the sealing groove. Two pads are respectively installed outside the two side walls of the flexible groove body, and the two ends of the multiple elastic members are respectively abutted between the inner side wall of the sealing groove and the pad.

[0016] In some embodiments, the elastic members abutting against each pad are at least arranged in two rows along the depth direction of the flexible groove body, and the elastic members in each row are evenly arranged;

[0017] When the elastic member is in a free state, the slot width of the flexible slot body is greater than the thickness of the plug plate, and the slot bottom width of the flexible slot is less than the thickness of the plug plate; the pad includes a first pad and a second pad, and the first pad and the second pad are respectively located at the outer wall of the flexible slot body, and the multiple elastic members include a plurality of first elastic members and a plurality of second elastic members; the first pad and the second pad are respectively arranged in parallel on the inner sides of the two side walls of the sealing slot, and the first end of the first elastic member is fixedly connected to the first pad, and the first end of the second elastic member is fixedly connected to the second pad.

[0018] In some embodiments, it also includes a threaded connecting rod and a handwheel, and a second screw hole is set on the top wall to pass through the upper and lower parts; the threaded connecting rod fits through the second screw hole and is rotatably connected to the upper end of the plug plate; the handwheel is fixed to the upper end of the threaded connecting rod, driving the threaded connecting rod to rotate, and the rotation plane is perpendicular to the extension direction of the threaded connecting rod.

[0019] In some embodiments, the flexible slot body includes an upper portion and a lower portion, and the slot width of the sealing slot gradually decreases from the slot opening of the flexible slot body to the lower end of the upper portion, and the slot width of the lower portion is the same as the minimum slot width of the upper portion;

[0020] In addition, the width of the lower groove is matched with the thickness of the plug board to seal the connection between the plug board and the sealing groove.

[0021] In some embodiments, the plurality of first elastic members and the plurality of second elastic members are springs.

[0022] In some embodiments, a third screw hole is provided at the bottom of the first slot body and the third slot body, and the first slot body has a second through hole extending from the bottom of the slot to the first side wall or the outer wall of the second side wall, and the second screw passes through the second through hole to fix the first slot body and the third slot body in the first slot respectively.

[0023] The beneficial effects of the utility model are:

[0024] The cleanable gate valve of the utility model is provided with a detachable base. The bottom of the gate valve in the prior art is often not detachable. The structure of the utility model can facilitate the disassembly of the gate valve base. The disassembled base is provided with a sealing groove, which can facilitate the cleaning of solids or colloids deposited on the sealing groove, thereby improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic front view of a gate valve provided in some embodiments of the utility model is shown;

[0027] Figure 2 A schematic diagram of a partial cross-section of a gate valve provided in some embodiments of the utility model is shown;

[0028] Figure 3 A partial schematic diagram of a front view of a gate valve provided in some embodiments of the utility model is shown.

[0029] Description of reference numerals:

[0030] 1. Hand wheel; 2. Threaded connecting rod; 3. Insert plate; 4. Sealing groove; 5. Second screw; 6. First screw; 7. Backing plate; 8. Elastic member; 9. Base; 10. Valve body frame; 101. Top wall; 102. Bottom wall; 103. First side wall; 104. Second side wall. DETAILED DESCRIPTION

[0031] The following is a further detailed description of the implementation of the utility model in conjunction with the accompanying drawings and examples. The detailed description of the following examples and the accompanying drawings are used to exemplarily illustrate the principles of the utility model, but cannot be used to limit the scope of the utility model. The utility model can be implemented in many different forms, not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0032] The utility model provides these embodiments to make the utility model thorough and complete, and fully express the scope of the utility model to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the components described in these embodiments should be interpreted as merely exemplary, rather than as a limitation.

[0033] It should be noted that, in the description of the present invention, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0034] In addition, the words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different parts. The words "include" or "comprise" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0035] It should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0036] All terms used in the present invention have the same meanings as those understood by ordinary technicians in the field to which the present invention belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.

[0037] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0038] like Figures 1 to 3 As shown, the embodiment of the utility model provides a cleanable plug valve, including a valve body frame 10, a base 9 and a plug plate 3, the valve body frame 10 includes a top wall 101, a bottom wall 102, a first side wall 103 and a second side wall 104, wherein the two ends of the top wall 101 are respectively connected to the upper ends of the first side wall 103 and the second side wall 104, and the two ends of the bottom wall 102 are respectively connected to the middle parts of the first side wall 103 and the second side wall 104;

[0039] The bottom wall 102 is provided with a first strip hole, and the inner walls of the first side wall 103 and the second side wall 104 are both provided with a first slot, and the plug board 3 extends through the first strip hole and is inserted into the first slot in an adaptive manner;

[0040] Furthermore, the base 9 is detachably connected to the lower ends of the first side wall 103 and the second side wall 104 , and a second slot for inserting the bottom end of the plugboard 3 is provided on the base 9 .

[0041] The base 9 of the utility model can be disassembled. When the plug plate 3 is connected to the pipe groove, it is easy to accumulate dirt on the valve body frame 10 as the plug plate 3 opens and closes, especially when the plug plate valve is connected to the flue gas pipe of the glass kiln, the flue gas of the glass kiln contains a large amount of boron trioxide dust and a large amount of free water molecules. The flue gas contains a large amount of boron trioxide dust, which gradually falls to the bottom of the valve due to gravity. The outdoor temperature is low in winter, resulting in a large temperature difference on the inner wall of the valve. The free water in the flue gas is cooled by the inner wall of the valve, and the gaseous water molecules become liquid water molecules. Because the boron trioxide deposits in the flue gas react strongly with the liquid water, sodium borate is produced. This type of substance is a colloid, and the colloid flows into the gap at the bottom of the valve along the gap. Because the valve passes through the high-temperature flue gas, the liquid sodium borate is heated at high temperature, and the sodium borate becomes a solid substance. The process of sodium borate changing from liquid to solid is repeated repeatedly, resulting in the continuous increase of solid colloid in the gate valve, which makes it impossible for the gate valve to be completely closed, causing valve smoke leakage and unstable kiln pressure. The bottom of the gate valve of the utility model is detachable, which is convenient for cleaning the solid substances in the gate 3 and the valve body frame 10, solving the problem of the difficulty in cleaning the solid substances on the gate valve in the prior art.

[0042] In some embodiments of the present invention, the lower ends of the first side wall 103 and the second side wall 104 are respectively provided with first screw holes, and two first through holes are provided on the base 9, and two first bolts pass through the two first through holes and are connected to the two first screw holes. The base 9 of the present invention is detachably connected to the valve body frame 10 by bolts, and when cleaning, the two first bolts are unscrewed, and the base 9 is easily disassembled.

[0043] In order to more conveniently realize the detachable connection between the base 9 and the valve body frame 10, in some embodiments, protrusions may be respectively provided at the lower ends of the first side wall 103 and the second side wall 104, and snap-fitting parts that can snap-fit ​​the protrusions may be respectively provided on the base 9, and the snap-fitting parts are snap-fitted and connected with the protrusions.

[0044] In some embodiments of the utility model, a sealing groove 4 is also fixed to the inner wall of the base 9, and the sealing groove 4 includes a U-shaped groove structure formed by a first groove body, a second groove body and a third groove body connected in sequence, the first groove body and the third groove body are inserted in two first slots in a fitting manner, the second groove body is inserted in the second slot in a fitting manner, the two sides of the plug board 3 are inserted in the first groove body and the third groove body in a fitting manner, and the bottom of the plug board 3 can be inserted in the second groove body in a fitting manner. The sealing groove 4 is welded to the base 9. Since the base 9 can be disassembled, when cleaning, the sealing groove 4 is disassembled along with the base 9, so that the sealing groove 4 can be cleaned more conveniently, so that it can better seal the gap between the plug board 3 and the valve body frame.

[0045] In order to further seal the gap between the plug plate 3 and the valve body frame 10, in some embodiments, as Figure 2 As shown, a flexible groove body, a pad 7 and multiple elastic members 8 are also provided in the sealing groove 4. Two pads 7 are respectively installed outside the two side walls of the flexible groove body, and two ends of the multiple elastic members 8 are respectively abutted between the inner side wall of the sealing groove 4 and the pad 7.

[0046] In some embodiments, Figure 2 As shown, the elastic members 8 abutting against each pad 7 are at least arranged in two rows along the depth direction of the flexible groove body, and the elastic members 8 in each row are evenly arranged;

[0047] When the elastic member 8 is in a free state, the slot width of the flexible slot body is greater than the thickness of the plug plate 3, and the slot bottom width of the flexible slot is less than the thickness of the plug plate 3; the pad 7 includes a first pad 7 and a second pad 7, and the first pad 7 and the second pad 7 are respectively located at the outer wall of the flexible slot body, and the multiple elastic members 8 include a plurality of first elastic members and a plurality of second elastic members 8; the first pad 7 and the second pad 7 are respectively arranged in parallel on the inner sides of the two side walls of the sealing slot 4, and the first end of the first elastic member is fixedly connected to the first pad 7, and the first end of the second elastic member 8 is fixedly connected to the second pad 7.

[0048] In the present invention, the flexible groove body is usually a high-temperature resistant and elastic polymer rubber sheet, such as a high-temperature resistant silicone sheet, to ensure sealing with the plug valve. Because the plug valve works at a high temperature for a long time, the plug plate 3 will be slightly deformed, which will cause air leakage. In some embodiments, an elastic member 8 is installed between the inner wall of the valve body sealing groove 4 and the gasket 7. When the plug plate 3 is inserted into the sealing groove 4, the plug plate 3 cannot be completely matched with the silicone due to deformation. The elastic member 8 behind the flexible groove body can apply pressure to the plug plate 3 to change the shape of the flexible groove body to achieve sealing.

[0049] In some embodiments of the utility model, in order to facilitate the movement of the plug plate 3 and control the opening and closing of the plug valve, a threaded connecting rod 2 and a hand wheel 1 are provided on the plug valve, and a second screw hole penetrating from top to bottom is provided on the top wall 101 of the plug valve; the threaded connecting rod 2 fits through the second screw hole and is rotatably connected to the upper end of the plug plate 3; the hand wheel 1 is fixed to the upper end of the threaded connecting rod 2, driving the threaded connecting rod 2 to rotate, and the rotation plane is perpendicular to the extension direction of the threaded connecting rod 2. By rotating the hand wheel 1, the opening and closing of the plug valve can be easily controlled.

[0050] In some embodiments, the flexible slot body includes an upper part and a lower part, and the slot width of the sealing slot 4 gradually decreases from the slot opening of the flexible slot body to the lower end of the upper part, and the slot width of the lower part is the same as the minimum slot width of the upper part;

[0051] Furthermore, the width of the lower groove is adapted to the thickness of the plug board 3 so as to seal the connection between the plug board 3 and the sealing groove 4 .

[0052] The sealing groove 4 of the utility model is designed so that the sealing groove 4 of the valve body is wide at the top and narrow at the bottom, which is more convenient for inserting the plug plate 3, reduces the influence of the plug plate 3 being unable to be inserted into the sealing groove 4 due to deformation, and avoids the plug plate 3 being too close to the silicone pad on the inner wall of the sealing groove 4 when deformed at high temperature, thereby wearing the pad 7 and reducing the service life.

[0053] In some embodiments, the plurality of first elastic members and the plurality of second elastic members 8 are springs. The utility model adopts springs to facilitate the adjustment of the force of the pad 7 according to the shape of the deformed plug board 3.

[0054] In some embodiments, a third screw hole is provided at the bottom of the first slot body and the third slot body, and the first slot body has a second through hole that passes through the bottom of the slot to the outer wall of the first side wall 103 or the second side wall 104, and the second screw 5 passes through the second through hole to fix the first slot body and the third slot body in the first slot respectively.

[0055] When cleaning the sealing groove 4 of the utility model, first remove the first screw 6 to separate the bottom from the valve body frame 10, remove the bottom while taking out the sealing groove 4 welded to the bottom, the pad 7 inside the sealing groove 4 wraps the side and bottom of the plug plate 3, clean the solid matter inside the sealing groove 4, and then reinstall the bottom with the sealing groove 4 and the valve body frame 10, so that the cleaning of the plug valve is completed.

[0056] So far, various embodiments of the present invention have been described in detail. Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. A cleanable gate valve, characterized in that: The valve body frame (10) comprises a valve body frame (10), a base (9) and a plug plate (3), wherein the valve body frame (10) comprises a top wall (101), a bottom wall (102), a first side wall (103) and a second side wall (104), wherein two ends of the top wall (101) are respectively connected to the upper ends of the first side wall (103) and the second side wall (104), and two ends of the bottom wall (102) are respectively connected to the middle parts of the first side wall (103) and the second side wall (104); The bottom wall (102) is provided with a first strip-shaped hole, the inner walls of the first side wall (103) and the second side wall (104) are both provided with a first slot, and the plug board (3) extends through the first strip-shaped hole and is inserted in the first slot in a fitting manner; Furthermore, the base (9) is detachably connected to the lower ends of the first side wall (103) and the second side wall (104), and a second slot is provided on the base (9) for inserting the bottom end of the plug board (3).

2. The cleanable gate valve according to claim 1, characterized in that: The lower ends of the first side wall (103) and the second side wall (104) are respectively provided with first screw holes, and the base (9) is provided with two first through holes, and two first bolts respectively pass through the two first through holes and are connected to the two first screw holes.

3. The cleanable gate valve according to claim 1, characterized in that: The lower ends of the first side wall (103) and the second side wall (104) are respectively provided with protrusions, and the base (9) is respectively provided with engaging pieces capable of engaging with the protrusions, and the engaging pieces are engaged and connected with the protrusions.

4. The cleanable gate valve according to claim 1, characterized in that: The inner wall of the base (9) is also fixed with a sealing groove (4), the sealing groove (4) comprising a U-shaped groove structure formed by a first groove body, a second groove body and a third groove body connected in sequence, the first groove body and the third groove body are adaptively inserted into the two first slots, the second groove body is adaptively inserted into the second slot, the two sides of the plug board (3) are adaptively inserted into the first groove body and the third groove body, and the bottom of the plug board (3) can be adaptively inserted into the second groove body.

5. The cleanable gate valve according to claim 4, characterized in that: A flexible groove body, a pad (7) and a plurality of elastic members (8) are also provided in the sealing groove (4); the two pads (7) are respectively mounted outside the two side walls of the flexible groove body; and the two ends of the plurality of elastic members (8) are respectively abutted between the inner side wall of the sealing groove (4) and the pad (7).

6. The cleanable gate valve according to claim 5, characterized in that: The elastic members (8) abutting against each of the pads (7) are arranged in at least two rows along the depth direction of the flexible trough body, and the elastic members (8) in each row are evenly arranged; When the elastic member (8) is in a free state, the slot width of the flexible slot body is greater than the thickness of the plug plate (3), and the slot bottom width of the flexible slot is less than the thickness of the plug plate (3); the pad (7) comprises a first pad (7) and a second pad (7), the first pad (7) and the second pad (7) are respectively located at the outer wall of the flexible slot body, and the plurality of elastic members (8) comprise a plurality of first elastic members and a plurality of second elastic members; the first pad (7) and the second pad (7) are respectively arranged in parallel on the inner sides of two side walls of the sealing slot (4), and the first end of the first elastic member is fixedly connected to the first pad (7), and the first end of the second elastic member is fixedly connected to the second pad (7).

7. The cleanable gate valve according to claim 5, characterized in that: It also comprises a threaded connecting rod (2) and a hand wheel (1), wherein a second screw hole penetrating from top to bottom is arranged on the top wall (101); the threaded connecting rod (2) adaptively passes through the second screw hole and is rotatably connected to the upper end of the plug plate (3); the hand wheel (1) is fixed to the upper end of the threaded connecting rod (2) to drive the threaded connecting rod (2) to rotate, and the rotation plane is perpendicular to the extension direction of the threaded connecting rod (2).

8. The cleanable gate valve according to claim 5, characterized in that: The flexible groove body comprises an upper part and a lower part, and the groove width of the sealing groove (4) gradually decreases from the groove opening of the flexible groove body to the lower end of the upper part, and the groove width of the lower part is the same as the minimum groove width of the upper part; Furthermore, the width of the groove at the lower portion is adapted to the thickness of the plug plate (3) so as to seal the connection between the plug plate (3) and the sealing groove (4).

9. The cleanable gate valve according to claim 6, characterized in that: The plurality of first elastic members and the plurality of second elastic members are springs.

10. The cleanable gate valve according to claim 5, characterized in that: The bottoms of the first slot body and the third slot body are both provided with a third screw hole, the first slot body has a second through hole extending from the bottom of the slot to the outer wall of the first side wall (103) or the second side wall (104), and a second screw (5) passes through the second through hole to fix the first slot body and the third slot body in the first slot respectively.

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