CN113091854A

CN113091854A - Explosion-proof tuning fork liquid level detection device

Info

Publication number: CN113091854A
Application number: CN202110444415.8A
Authority: CN
Inventors: 刘斌; 曹彩丽; 刘赟贝贝
Original assignee: Henan Feipusite Instruments And Meters Co ltd
Current assignee: Henan Feipusite Instruments And Meters Co ltd
Priority date: 2021-04-23
Filing date: 2021-04-23
Publication date: 2021-07-09

Abstract

The invention discloses an explosion-proof tuning fork liquid level detection device which comprises an outer shell, an explosion-proof armored cable sealing joint, a sensor element, a connecting piece and a top cover, wherein a material level controller is arranged inside the outer shell, the explosion-proof armored cable sealing joint is arranged on the outer side of the outer shell, the bottom end of the outer shell is connected with the connecting piece, a first sealing ring is installed at the top end of the connecting piece, a fork body is connected below the connecting piece, a connecting flange is arranged on the outer side of the connecting piece, a fixing hole is formed in the side edge of the connecting flange, the top cover is connected to the top end of the outer shell, a sliding block is installed at the bottom of the inner side of the. This explosion-proof tuning fork liquid level detection device can adjust the installation and use, and can guarantee that the position is adjusted well, is favorable to guaranteeing long-term job's stability, is convenient for carry on stable dismouting simultaneously.

Description

Explosion-proof tuning fork liquid level detection device

Technical Field

The invention relates to the technical field of liquid level detection of an explosion-proof tuning fork, in particular to a liquid level detection device of an explosion-proof tuning fork.

Background

The explosion-proof tuning fork liquid level detection switch device is designed by utilizing the principle that the frequency between tuning forks changes along with the difference of media, when the tuning forks change from a dry state to a wet state or from the wet state to the dry state, the change causes frequency change, can be detected by a wet state or dry state electric sensor, and is converted into corresponding switching value signals or 4-20mA signals through an intelligent electronic device to be output so as to provide switching value alarm;

the anti-explosion tuning fork switch is free from the influence of medium electrical parameters, turbulence, stirring, bubbles, vibration and other factors when in use, has no movable parts, does not need maintenance and adjustment, is an ideal choice of the material level switch under complex working conditions, has strong adaptability, does not generate influence on measurement by different electrical parameters and densities of a measured material, does not need maintenance, and can adapt to different severe environments;

and explosion-proof tuning fork liquid level detection device under the prior art background still has certain drawback when using, if:

1. most of the existing explosion-proof tuning fork liquid level detection devices are installed and used by adopting flange installation or direct threaded connection, so that the existing explosion-proof tuning fork liquid level detection devices cannot be automatically adjusted and used during installation operation, cannot ensure the stability of installation and connection, and are not beneficial to long-term use;

2. when the general explosion-proof tuning fork liquid level detection device is used for a long time, the tightness of the installation and the use of the device can be influenced due to the influence of physical conditions such as air pressure, hydraulic pressure and the like, the device needs to be overhauled, and the device is not favorable for long-term stable operation and use;

3. when the common explosion-proof tuning fork liquid level detection device is used, the cover body structure is generally in threaded connection or direct clamping arrangement, so that the quick disassembly and assembly are inconvenient, the stability of the cover body installation is inconvenient to ensure, and the internal elements are not favorably prevented from being unnecessarily damaged;

therefore, we propose an explosion-proof tuning fork liquid level detection device so as to solve the problems proposed in the above.

Disclosure of Invention

The invention aims to provide an explosion-proof tuning fork liquid level detection device, and aims to solve the problems that the conventional explosion-proof tuning fork liquid level detection device provided by the background technology cannot be automatically adjusted, installed and used, is not beneficial to ensuring the stability of long-term work, and is inconvenient to rapidly and stably disassemble and assemble.

In order to achieve the purpose, the invention provides the following technical scheme: an explosion-proof tuning fork liquid level detection device comprises an outer shell, an explosion-proof armored cable sealing joint, a sensor element, a connecting piece and a top cover, wherein a material level controller is arranged inside the outer shell, an internal grounding end is installed at the top of the material level controller, the explosion-proof armored cable sealing joint is arranged on the outer side of the outer shell, a first plug which is also located on the outer side of the outer shell is arranged on the rear side of the explosion-proof armored cable sealing joint, a second plug is arranged above the position between the explosion-proof armored cable sealing joint and the first plug, and an external grounding end is arranged below the second plug;

the bottom end of the outer shell is connected with a connecting piece, a compression nut is arranged at the top of the outer side of the connecting piece, a first sealing ring is installed at the top end of the connecting piece, a fork body is connected below the connecting piece, a vibrating piece is arranged on the side of the bottom edge of the fork body, a notch is formed in the middle of the bottom of the fork body, a connecting flange is arranged on the outer side of the connecting piece, an inner ring plate is fixed on the inner side of the connecting flange, a fixing hole is formed in the side of the connecting flange, a boss is arranged on the outer side of the top of the fixing hole, a second sealing ring is arranged on the outer side of the boss, and;

the top cap is connected on the top of shell body, and the top of top cap has seted up the undercut groove, the slider is installed to the inboard bottom of top cap, and the top correspondence of slider is fixed with the fixture block, the top outside of shell body is provided with the counterpoint groove, and the bottom in counterpoint groove is connected with the groove of stepping down, the inboard bottom in groove of stepping down is provided with the buckle, and the bottom of buckle has seted up the draw-in groove.

Preferably, explosion-proof armoured cable sealing joint through connection is on the right side of shell body, and corresponds sealed laminating between explosion-proof armoured cable sealing joint and the shell body to between explosion-proof armoured cable sealing joint, first end cap and the second end cap all and the shell body zonulae occludens.

Preferably, the sensor element is correspondingly connected with the level controller through a connecting wire, the sensor element is correspondingly connected to the middle position of the top of the fork body, and the fork body is correspondingly arranged at the bottom of the connecting piece.

Preferably, the connecting piece corresponds between mode and the shell body that passes through threaded connection and is connected, and the top external diameter of connecting piece is greater than the bottom external diameter of connecting piece to the top outside of connecting piece and the bottom outside of connecting piece all are helicitic texture, and gland nut is all installed to the top and the bottom of connecting piece all correspondence simultaneously.

Preferably, the top of connecting piece is through closely laminating between first sealing washer and the shell body, and corresponds the pressfitting setting between gland nut and the first sealing washer to correspond sealing connection between the bottom of connecting piece and the fork body, the middle part front side of connecting piece is provided with the sign piece moreover.

Preferably, be fixed integral structure between flange and the interior crown plate, and flange corresponds threaded connection between through interior crown plate and the connecting piece to flange's avris equiangular has seted up the fixed orifices, and flange's western corresponds the subsides in addition and has sealed the pad.

Preferably, the inside of interior crown plate is the longitudinal symmetry and has seted up the spacing groove, and the inside correspondence of spacing groove installs the third sealing washer to interior crown plate passes through and closely laminates between third sealing washer and the connecting piece.

Preferably, the bosses are arranged on the outer sides of the fixing holes in a one-to-one correspondence mode, the bosses are arranged on the top surfaces of the protruding connecting flanges, the bosses are sleeved with the second sealing rings in a corresponding mode, grooves are formed in the upper surfaces and the lower surfaces of the second sealing rings, and meanwhile the inner sides of the second sealing rings are connected with the locking bolts.

Preferably, the top cover and the outer shell are correspondingly formed into a detachable structure, the top cover and the outer shell are tightly attached through a fourth sealing ring, and the fourth sealing ring is arranged between the outer shell and the top cover.

Preferably, be corresponding block sliding construction between slider and the counterpoint groove, and be the intercommunication setting between counterpoint groove and the groove of stepping down to the buckle constitutes elastic construction in the inboard in the groove of stepping down, and the buckle passes through the draw-in groove and corresponds the block between the setting and the slider between the fixture block and is connected.

Compared with the prior art, the invention has the beneficial effects that: the anti-explosion tuning fork liquid level detection device can be adjusted, installed and used, and can ensure the position alignment, thereby being beneficial to ensuring the stability of long-term work and being convenient for stable disassembly and assembly;

1. the connecting piece, the connecting flange, the inner ring plate, the dead bolt and the identification block are arranged in the scheme, stable assembly can be carried out through corresponding connection between the connecting piece and the outer shell and the fork body, meanwhile, rotation adjustment is convenient to carry out through threaded connection between the connecting piece and the inner ring plate, meanwhile, stability can be guaranteed through pressing of the compression nut, position fixing is carried out through the connecting flange and the dead bolt, installation stability can be guaranteed, position indication of the fork body is facilitated through the identification block, and alignment installation is guaranteed;

2. the sealing structure is provided with the compression nut, the first sealing ring, the second sealing ring, the sealing gasket and the third sealing ring, the first sealing ring is upwards extruded through the compression nut, meanwhile, the sealing ring is arranged between the bottom end of the outer shell and the inner side of the connecting piece, sealing between the connecting piece and the outer shell can be guaranteed, sealing performance of installation of the connecting flange can be guaranteed through the arrangement of the second sealing ring and the sealing gasket, and overall sealing is guaranteed through attachment between the third sealing ring and the connecting piece;

3. be provided with slider, fixture block, counterpoint groove and buckle in this scheme, through the corresponding block between slider and the counterpoint groove, can install the top cap, and rotate through the counterpoint top cap, can make the slider rotate in the bottom in counterpoint groove for the slider passes through the block between fixture block and the buckle, guarantees the stability of connecting, and is convenient for carry out the dismouting.

Drawings

FIG. 1 is a side sectional view of the present invention;

FIG. 2 is a schematic front view of the present invention;

FIG. 3 is an enlarged view of portion A of FIG. 1 according to the present invention;

FIG. 4 is a schematic view of the overall structure of the connector of the present invention;

FIG. 5 is a schematic view of the overall structure of the fork body of the present invention;

FIG. 6 is a schematic view of the overall construction of the attachment flange and inner ring plate of the present invention;

FIG. 7 is a schematic top view of the outer housing of the present invention;

FIG. 8 is a schematic view of the overall structure of the top cover of the present invention;

fig. 9 is a front sectional structure diagram of the top cover of the present invention.

In the figure: 1. an outer housing; 2. a material level controller; 3. an inner grounding end; 4. an explosion-proof armored cable sealing joint; 5. a first plug; 6. a second plug; 7. the grounding end is externally connected; 8. a connecting wire; 9. a sensor element; 10. a connecting member; 11. a compression nut; 12. a first seal ring; 13. a fork body; 14. a vibrating piece; 15. a recess; 16. a connecting flange; 17. an inner ring plate; 18. a fixing hole; 19. a boss; 20. a second seal ring; 21. locking the dead bolt; 22. a groove; 23. a gasket; 24. a limiting groove; 25. a third seal ring; 26. an identification block; 27. a top cover; 28. an invagination groove; 29. a slider; 30. a clamping block; 31. a positioning groove; 32. a yielding groove; 33. buckling; 34. a card slot; 35. and a fourth seal ring.

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.

Referring to fig. 1-9, the present invention provides a technical solution: an explosion-proof tuning fork liquid level detection device comprises an outer shell 1, a material level controller 2, an internal grounding end 3, an explosion-proof armored cable sealing joint 4, a first plug 5, a second plug 6, an external grounding end 7, a connecting wire 8, a sensor element 9, a connecting piece 10, a gland nut 11, a first sealing ring 12, a fork body 13, a vibrating piece 14, a notch 15, a connecting flange 16, an inner ring plate 17, a fixing hole 18, a boss 19, a second sealing ring 20, a locking bolt 21, a groove 22, a sealing gasket 23, a limiting groove 24, a third sealing ring 25, a marking block 26, a top cover 27, an internal sunken groove 28, a sliding block 29, a clamping block 30, a positioning groove 31, a yielding groove 32, a buckle 33, a clamping groove 34 and a fourth sealing ring 35, wherein the material level controller 2 is arranged inside the outer shell 1, the internal grounding end 3 is arranged at the top of the material level controller 2, the external grounding end 4 is arranged outside, a first plug 5 which is also positioned at the outer side of the outer shell 1 is arranged at the rear side of the explosion-proof armored cable sealing joint 4, a second plug 6 is arranged above the space between the explosion-proof armored cable sealing joint 4 and the first plug 5, and an external grounding end 7 is arranged below the second plug 6;

the bottom end of the outer shell 1 is connected with a connecting piece 10, the top of the outer side of the connecting piece 10 is provided with a compression nut 11, the top end of the connecting piece 10 is provided with a first sealing ring 12, the lower part of the connecting piece 10 is connected with a fork body 13, the bottom edge side of the fork body 13 is provided with a vibrating piece 14, the middle position of the bottom of the fork body 13 is provided with a notch 15, the outer side of the connecting piece 10 is provided with a connecting flange 16, the inner side of the connecting flange 16 is fixed with an inner ring plate 17, the edge side of the connecting flange 16 is provided with a fixing hole 18, the outer side of the top of the fixing hole 18 is provided with a boss 19, the outer side of the boss 19 is;

the top cap 27 is connected on the top of shell body 1, and the top of top cap 27 has seted up sunken groove 28, and slider 29 is installed to the inboard bottom of top cap 27, and the top of slider 29 corresponds and is fixed with fixture block 30, and the top outside of shell body 1 is provided with counterpoint groove 31, and the bottom of counterpoint groove 31 is connected with the groove 32 of stepping down, and the inboard bottom of the groove 32 of stepping down is provided with buckle 33, and draw-in groove 34 has been seted up to the bottom of buckle 33.

As in fig. 1 and 2, the explosion-proof armored cable sealing joint 4 is connected to the right side of the outer shell 1 in a penetrating manner, the explosion-proof armored cable sealing joint 4 and the outer shell 1 are correspondingly attached in a sealing manner, and the explosion-proof armored cable sealing joint 4, the first plug 5 and the second plug 6 are all connected with the outer shell 1 in an intimate manner, so that the assembly connection is convenient to use.

The sensor element 9 is correspondingly connected with the level controller 2 through the connecting wire 8 as shown in fig. 1, fig. 2, fig. 3 and fig. 4, the sensor element 9 is correspondingly connected at the top middle position of the fork body 13, and the fork body 13 is correspondingly installed at the bottom of the connecting piece 10, so that the corresponding connection detection measurement use is facilitated.

As in fig. 1, correspond between mode and the shell body 1 that connecting piece 10 passes through threaded connection in fig. 3 and fig. 4 and be connected, and the top external diameter of connecting piece 10 is greater than the bottom external diameter of connecting piece 10, and the top outside of connecting piece 10 and the bottom outside of connecting piece 10 all are the helicitic texture, simultaneously the top and the bottom of connecting piece 10 all correspond and install gland nut 11, you can guarantee the compactness of being connected between connecting piece 10 and the shell body 1, the top of connecting piece 10 is through closely laminating between first sealing washer 12 and the shell body 1, and correspond the pressfitting setting between gland nut 11 and the first sealing washer 12, and correspond sealing connection between the bottom of connecting piece 10 and the forked body 13, and the middle part front side of connecting piece 10 is provided with identification block 26, be convenient for through the position of identification block 26 sign forked body 13, be convenient for adjust.

As shown in fig. 6, the connecting flange 16 and the inner ring plate 17 are of a fixed integrated structure, the connecting flange 16 is in corresponding threaded connection with the connecting member 10 through the inner ring plate 17, the sides of the connecting flange 16 are provided with fixing holes 18 at equal angles, the west of the connecting flange 16 is correspondingly coated with a sealing gasket 23 which can be tightly installed, the inner part of the inner ring plate 17 is provided with limiting grooves 24 in a vertical symmetry manner, the inner part of the limiting grooves 24 is correspondingly provided with third sealing rings 25, the inner ring plate 17 is tightly attached with the connecting member 10 through the third sealing rings 25, so that the inner attachment can be ensured, the sealing connection is ensured, the long-term stable use is facilitated, the outer sides of the fixing holes 18 are correspondingly provided with bosses 19, the bosses 19 are arranged to protrude out of the top surface of the connecting flange 16, the bosses 19 are correspondingly sleeved with the second sealing rings 20, and the upper and lower surfaces of the second sealing rings 20, meanwhile, the inner side of the second sealing ring 20 is connected with a dead locking bolt 21, so that sealing and fixing are facilitated.

Corresponding constitution dismantlement structure between top cap 27 and shell body 1 as in fig. 1, fig. 7, fig. 8 and fig. 9, and closely laminate through fourth sealing washer 35 between top cap 27 and the shell body 1, and fourth sealing washer 35 is placed between shell body 1 and top cap 27, the top cap 27 installation of being convenient for, avoid intaking into dirt, be corresponding block sliding structure between slider 29 and the counterpoint groove 31, and be the intercommunication setting between counterpoint groove 31 and the groove 32 of stepping down, and buckle 33 constitutes elastic construction at the inboard of the groove 32 of stepping down, and buckle 33 corresponds the block through the setting that corresponds between draw-in groove 34 and the block 30 and be connected with slider 29, the operation of being convenient for, can guarantee stably, convenient to use.

The working principle is as follows: when the anti-explosion tuning fork liquid level detection device is used, firstly, as shown in fig. 1, fig. 2, fig. 3 and fig. 4, the depth of the connecting piece 10 inside the inner ring plate 17 is adjusted through the threaded connection between the inner ring plate 17 and the connecting piece 10, then the connecting flange 16 is attached to the position to be installed, so that the inner ring plate 17 extends into the installation hole, the fixing is performed through the corresponding penetration between the locking bolt 21 and the fixing hole 18, the sealing performance is enhanced through the corresponding arrangement of the second sealing ring 20 between the locking bolt 21 and the connecting flange 16, and then the pressing nut 11 on the outer side of the bottom of the connecting piece 10 is screwed downwards, so that the pressing nut 11 presses the inner ring plate 17 downwards, thereby ensuring the relative stability between the connecting piece 10 and the inner ring plate 17, ensuring the position alignment, and simultaneously, the third sealing ring 25 is installed on the inner side of the inner ring plate 17 to ensure the attachment sealing during the use, so as to ensure stable use;

when the device is used, the bottom of the fork body 13 is deep under the liquid level or particles so as to be put into use, and the sensor element 9 is used for sensing and sending signals so as to ensure the completion of the measurement work;

meanwhile, when operation is required, as shown in fig. 7, 8 and 9, the top cover 27 slides downwards through the corresponding clamping between the sliding block 29 and the alignment groove 31, when the top cover 27 slides to the bottommost part, the fourth sealing ring 35 is extruded, dust and water can be prevented from entering between the top cover 27 and the outer shell 1, meanwhile, the top cover 27 is rotated, so that the sliding block 29 synchronously rotates, and therefore the sliding block 29 is clamped with the buckle 33 through the corresponding arrangement between the clamping block 30 and the clamping groove 34, and the buckle 33 is of an elastic structure on the inner side of the alignment groove 32, which is beneficial to ensuring stability and facilitating operation.

The standard parts used in the invention can be purchased from the market, the special-shaped parts can be customized according to the description of the specification and the accompanying drawings, the specific connection mode of each part adopts conventional means such as bolts, rivets, welding and the like mature in the prior art, the machines, the parts and equipment adopt conventional models in the prior art, and the circuit connection adopts the conventional connection mode in the prior art, so that the detailed description is omitted.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and/or modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.

Claims

1. The utility model provides an explosion-proof tuning fork liquid level detection device, includes shell body (1), explosion-proof armoured cable sealing joint (4), sensor element (9), connecting piece (10) and top cap (27), its characterized in that: a material level controller (2) is arranged inside the outer shell (1), an inner grounding end (3) is installed at the top of the material level controller (2), an anti-explosion armored cable sealing joint (4) is arranged on the outer side of the outer shell (1), a first plug (5) which is also located on the outer side of the outer shell (1) is arranged on the rear side of the anti-explosion armored cable sealing joint (4), a second plug (6) is arranged above the position between the anti-explosion armored cable sealing joint (4) and the first plug (5), and an outer grounding end (7) is arranged below the second plug (6);

the bottom end of the outer shell (1) is connected with a connecting piece (10), the top of the outer side of the connecting piece (10) is provided with a compression nut (11), a first sealing ring (12) is arranged at the top end of the connecting piece (10), a fork body (13) is connected below the connecting piece (10), a vibrating piece (14) is arranged on the bottom edge side of the fork body (13), a notch (15) is arranged in the middle of the bottom of the fork body (13), a connecting flange (16) is arranged on the outer side of the connecting piece (10), an inner ring plate (17) is fixed on the inner side of the connecting flange (16), a fixing hole (18) is arranged on the side of the connecting flange (16), a boss (19) is arranged on the outer side of the top of the fixing hole (18), a second sealing ring (20) is arranged on the outer side of the boss (19), and a locking bolt (21) is connected above the second sealing ring (20);

the top cap (27) is connected on the top of shell body (1), and sunken groove (28) have been seted up at the top of top cap (27), slider (29) are installed to the inboard bottom of top cap (27), and the top correspondence of slider (29) is fixed with fixture block (30), the top outside of shell body (1) is provided with counterpoint groove (31), and the bottom of counterpoint groove (31) is connected with groove (32) of stepping down, the inboard bottom of groove (32) of stepping down is provided with buckle (33), and draw-in groove (34) have been seted up to the bottom of buckle (33).

2. The explosion-proof tuning fork liquid level detection device of claim 1, wherein: explosion-proof armoured cable sealing joint (4) through connection is on the right side of shell body (1), and corresponds sealed laminating between explosion-proof armoured cable sealing joint (4) and shell body (1) to between explosion-proof armoured cable sealing joint (4), first end cap (5) and second end cap (6) all and shell body (1) zonulae occludens.

3. The explosion-proof tuning fork liquid level detection device of claim 1, wherein: the sensor element (9) is correspondingly connected with the level controller (2) through a connecting wire (8), the sensor element (9) is correspondingly connected to the middle position of the top of the fork body (13), and the fork body (13) is correspondingly installed at the bottom of the connecting piece (10).

4. The explosion-proof tuning fork liquid level detection device of claim 1, wherein: the connecting piece (10) corresponds between mode through threaded connection and shell body (1) and is connected, and the top external diameter of connecting piece (10) is greater than the bottom external diameter of connecting piece (10) to the top outside of connecting piece (10) and the bottom outside of connecting piece (10) all are helicitic texture, and gland nut (11) are all installed to the top and the bottom of connecting piece (10) all correspond simultaneously.

5. The explosion-proof tuning fork liquid level detection device of claim 1, wherein: the top of connecting piece (10) is through closely laminating between first sealing washer (12) and shell body (1), and corresponds the pressfitting setting between gland nut (11) and first sealing washer (12) to correspond sealing connection between the bottom of connecting piece (10) and fork body (13), the middle part front side of connecting piece (10) is provided with identification block (26) moreover.

6. The explosion-proof tuning fork liquid level detection device of claim 1, wherein: be fixed integrated into one piece structure between flange (16) and interior crown plate (17), and flange (16) correspond threaded connection through between interior crown plate (17) and connecting piece (10) to fixed orifices (18) have been seted up to the angles such as avris of flange (16), and the western correspondence of flange (16) is applied and is sealed (23).

7. The explosion-proof tuning fork liquid level detection device of claim 6, wherein: the inside of interior crown plate (17) is the longitudinal symmetry and has seted up spacing groove (24), and the inside correspondence of spacing groove (24) installs third sealing washer (25) to interior crown plate (17) is through closely laminating between third sealing washer (25) and connecting piece (10).

8. The explosion-proof tuning fork liquid level detection device of claim 1, wherein: the outside one-to-one of fixed orifices (18) is provided with boss (19), and boss (19) are the top surface setting of protrusion flange (16) to correspond between boss (19) and second sealing washer (20) and cup joint, the upper and lower surface of second sealing washer (20) all sets up fluted (22) moreover, and the inboard of second sealing washer (20) is connected with deadlock bolt (21) simultaneously.

9. The explosion-proof tuning fork liquid level detection device of claim 1, wherein: correspond between top cap (27) and shell body (1) and constitute and dismantle the structure, and closely laminate through fourth sealing washer (35) between top cap (27) and shell body (1) to fourth sealing washer (35) are placed between shell body (1) and top cap (27).

10. The explosion-proof tuning fork liquid level detection device of claim 1, wherein: be corresponding block sliding structure between slider (29) and counterpoint groove (31), and be the intercommunication setting between counterpoint groove (31) and the groove of stepping down (32) to buckle (33) constitute elastic construction in the inboard in groove of stepping down (32), and buckle (33) correspond the block through setting between draw-in groove (34) and fixture block (30) and are connected with slider (29) between the block that corresponds.