KR20180072292A - Safety packing for pressure cooker - Google Patents

Abstract

The present invention relates to a safety packing for a pressure rice cooker and, more specifically, to a safety packing for a pressure rice cooker which is fitted into a space formed inside a lid of a pressure rice cooker used to cook a food such as rice. The safety packing comprises: a body having a ring shape and capable of being elastically deformed; an upper contact part extended from an upper part of the body to be closely attached to the lid or closely attached to a container coupled to the lid to be rotated; a lower contact part extended from a lower part of the body to closely adhere to the lid or to be closely attached to the lid to be rotated; and at least one groove formed on one surface of the body on which the upper contact part and the lower contact part are extended. The safety packing (rubber packing), which is one of safety devices of the pressure rice cooker, can be easily deformed, and thus it is possible to easily discharge internal pressure generated during cooking and secure safety. In addition, the present invention can further improve an adhering state by being easily bent out by the internal pressure. Moreover, the safety packing can be easily moved back and forth by a pressing button provided in the pressure rice cooker when cooking is completed, and thus a user can be provided with convenience according to a use. Therefore, it is possible to provide convenience according to the use of a user. In addition, the present invention can improve an original sealing function by easily bending out the upper contact part and the lower contact part due to the groove formed in the body. Also, the present invention reduces force to be pressed when the lid is put on the body to be closed, and thus it is possible to provide convenience in use. Furthermore, the present invention can easily bend out the safety packing, and thus cleaning can be cleanly performed to maintain a clean hygiene state.

Description

{SAFETY PACKING FOR PRESSURE COOKER}

The present invention relates to a safety packing for a pressure cooker, and more particularly, to a safety packing for a pressure cooker (rubber packing) which can easily be deformed. The safety packing can be easily moved forward and backward by the pressure button provided on the pressure cooker when the cooking is completed, so that the pressure for providing convenience to the user The present invention relates to a safety packing for a rice cooker.

In general, the pressure cooker used in the home can perform cooking in a high temperature and high pressure atmosphere to the object to be cooked charged in the container. When the lid is closed to the container for charging the object to be cooked, The airtightness that can maintain the high temperature and high pressure state set at the time is absolutely required.

It is very important that the pressure cooker of the pressure cooker is not leaked to the outside. For this reason, in order to seal the inside of the container, all of the pressure cooker lids are provided with rubber packing, do.

The pressure cooker is mainly used as a tool to cook rice by putting washed rice in a container and heating it with heating means after closing the lid.

The pressure cooker is designed to open the lid when all the steam inside the container has been removed after cooking. However, there is a safety accident that the lid is exploded by the user forcibly opening the lid even though the steam inside the container often remains at high pressure.

These lid explosion safety accidents often occur because the user does not observe the user's instructions properly, rather than the product itself. In particular, the pressure cooker needs to cook only a certain kind of food such as rice, and is used by the user to ignore the regulations and to cook steamed rice, samgyetang or various kinds of porridge.

For example, when cooking steamed or samgyetang oil, the oil is sandwiched between the container and the lid or between the lid and the rubber packing, so that the lid and the body or the rubber packing are in close contact with each other, There is a problem that the lid is relatively easily rotated due to the residual steam and the lid is opened.

In addition, finely chopped vegetables or bean husks used in porridge cooking are inserted into the gaps of the steam outlet such as the pressure control valve and the safety valve to prevent the internal steam from being discharged to the outside, and the pressure control valve and the safety valve are normally operated It prevents things.

In this way, when the lid is opened under a high pressure, the lid is protruded upward, so that the kitchen hood can be damaged even if there is no direct personal injury, the damaged pieces generated by the damaged kitchen hood can damage the user, This can lead to personal injury that can cause fatal damage to the user.

FIG. 1 is a perspective view showing a conventional pressure cooker according to an embodiment of the present invention. The pressure cooker 10 includes a substantially cylindrical container 11, a lid 12 rotatably coupled to the upper end of the container 11, And a ring-shaped rubber packing 13 interposed between the cap 12 and the lid 12.

As shown in the figure, the lid 12 is provided with a pressure regulating valve 12a for discharging the internal pressure to open when the inner pressure reaches a pressure suitable for cooking, and a malfunction of the pressure regulating valve 12a or a pressure regulating valve A safety valve 12b is provided to be opened when the internal pressure increases beyond a set value even in a state in which the valve 12a is operated.

The lid 12 is provided with a handle 12c on both sides and the container 11 and the lid 12 are opened before opening the lid 12 on one of the knobs 12c on both sides. A pressing button 12d is formed which pushes the rubber packing 13 interposed between the inner tube 11 and the inner tube 11 to discharge the inner vapor of the container 11 to the outside.

FIG. 2 is a perspective view of one embodiment of a rubber packing according to the prior art, wherein the rubber packing 13 is ring-shaped and includes a body 13a that contacts one surface of the lid 12, And an upper close contact portion 13b and a lower close contact portion 13c which are extended to the upper and lower surfaces of the lid 12, respectively.

As shown in the figure, the thickness of the body 13a, the upper close contact portion 13b and the lower close contact portion 13c of the conventional rubber packing 13 is thick.

However, the conventional rubber packing 13 is one of the safety devices. As shown in the drawing, the thickness of the rubber packing 13 is so thick that the inner pressure can not be easily discharged between the container 11 and the lid 12, There is a problem in safety.

Even if the internal pressure is discharged, the pressure cooker 10 is rolled down or a large explosion occurs due to the high pressure.

Further, there is a safety valve 12b installed in the lid 12, which is clogged with rice balls even if it is operated.

The conventional rubber packing 13 may be configured such that the pressure button 12d formed on the handle 12c is pressed against the rubber packing 13 to separate the lid 12 from the container 11 after completion of cooking. The one side of the rubber packing 13 to be pushed in is too thick to be pressed strongly so that it is inconvenient for a woman or an elderly person having a weak hand force such as a relatively strong grip.

The related prior art is disclosed in Korean Utility Model Registration No. 20-0286207 (entitled: Pressure Packing for Safety Packing for Pressure Cooker, Registered Date: Aug. 06, 2002) and Published Patent Application No. 10-2003-0097433 The name of the invention: packing for pressure regulation, open date: December 31, 2003).

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a pressure cooker which can easily deform a safety packing (rubber packing) And it is possible to further improve the close contact state by the internal pressure. Further, when the cooking is completed, the safety packing can be easily advanced and retreated by the pressure button provided in the pressure cooker, thereby providing convenient convenience to the user Pressure cooker for pressure cooker.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

In order to achieve the above object, the present invention has the following technical features.

The safety packing for a pressure cooker according to the present invention is a safety packing for a pressure cooker which is fitted in a space formed inside a lid of a pressure cooker used for cooking cooked foods such as rice, An upper contact portion extending from an upper portion of the body and being in close contact with a lid or a container which is rotatably coupled to the lid, and an upper contact portion extending from the lower portion of the body and being in close contact with the lid, And a groove formed on at least one surface of the body on which the upper close portion and the lower close portion are extended.

In the safety packing for a pressure cooker according to the present invention, the safety packing may be configured such that a limit adjustment of pressure generated in the sealed state by the coupling of the container and the lid is controlled by the thickness of the body, By adjusting the thickness of the upper close contact portion and the lower close contact portion.

In the safety packing for a pressure cooker according to the present invention, the safety packing has a depth of 0.3 mm to 2.0 mm and a width of the groove of 0.7 mm to 1.5 mm based on a thickness of 4 mm of the body.

In the safety packing for a pressure cooker according to the present invention, the thickness of the safety packing is about 4 mm in thickness of the body, and the thickness of the upper close part and the lower close part is 0.7 mm to 2.7 mm.

In the safety packing for a pressure cooker according to the present invention, the thickness of the body is thicker than the thickness of the upper close contact portion and the lower close contact portion.

In the safety packing for a pressure cooker according to the present invention, the upper tight contact portion and the lower tight contact portion are formed to be inclined upward and downward from the body, respectively.

In the safety packing for a pressure cooker according to the present invention, the upper tight contact portion and the lower tight contact portion are inclined at an angle of 130 ° to 150 ° with respect to the upper and lower directions, respectively, from the body.

In the safety packing for a pressure cooker according to the present invention, one surface of the body extending from the upper tightening portion and the lower tightening portion is formed in a round shape.

In the safety packing for a pressure cooker according to the present invention, a groove formed on one surface of the body is formed to become narrower inwardly from a portion extended from the upper tightening portion and the lower tightening portion.

According to the present invention, since the safety packing (rubber packing), which is one of the safety devices of the pressure cooker, can be easily deformed through the solution of the above problems, the internal pressure generated during cooking is easily discharged, It is possible to further improve the close contact state by the pressure, and the safety packing can be easily advanced and retreated by the press button provided on the pressure cooker when the cooking is completed, thereby providing convenient convenience to the user.

In addition, the present invention can improve the original sealing function by allowing the upper and lower contact portions to easily be tilted by the groove formed in the body, as well as to reduce the force to be pushed on the body when the lid is placed on the body, to provide.

In addition, since the safety packing can be easily tilted by the present invention, clean cleaning can be performed, and a clean sanitary condition can be maintained.

Other advantages of the present invention can be understood through the features of the present invention,

Can be more clearly understood through examples, and can be exercised by the means and combinations disclosed in the claims.

1 is a perspective view showing a conventional pressure cooker according to an embodiment of the present invention,
2 is a perspective view of one embodiment of a conventional rubber packing,
3 is a perspective view of one embodiment of a safety packing according to the present invention,
Fig. 4 is a perspective view showing a state in which a part of the safety packing according to Fig.
Fig. 5 is a perspective view showing a state in which the shape of the safety packing according to Fig. 3 is deformed,
Figure 6 is a perspective view of another embodiment of the safety packing according to Figure 3,
Figure 7 is a perspective view of another embodiment of the safety packing according to Figure 3;

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with one embodiment. It should also be understood that the position or arrangement of individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled. In the drawings, like reference numbers refer to the same or similar function in various aspects.

Fig. 3 is a perspective view of one embodiment of the safety packing according to the present invention, Fig. 4 is a perspective view showing a state in which a part of the safety packing according to Fig. 3 is sectioned, Fig. 5 is a cross- Fig.

The pressure cooker 100 according to the present invention comprises a container 110, a lid 120, and a safety packing 130 interposed between the container 110 and the lid 120.

The container 110 is formed with a receiving space for receiving food items such as rice, and is placed and heated by a heating means such as a gas range, an electric range, and an induction range.

The lid 120 is rotatably coupled to the upper end of the container 110 and is formed in a circular shape like the container 110 to be coupled to the upper end of the container 110 to seal the inside of the container 110.

The safety packing 130 is interposed between the container 110 and the lid 120 and is fitted into a space formed inside the lid 120. The safety packing 130 is made of silicone, Rubber, and natural rubber.

The safety packing 130 is fitted to the lid 120 of the pressure cooker 100 to serve as a gasket for sealing the inside of the pressure cooker 100 when cooking the cooked food.

3 to 5, the safety packing 130 for a pressure cooker according to the present invention includes a body 131, an upper close contact portion 132, a lower close contact portion 133, and a groove 134 .

The body 131 is ring-shaped and elastically deformable.

Specifically, the body 131 is fitted into the space formed around the inner surface of the lid 120, and is closely attached to the space coupled with the increased pressure inside the container 110, and is not pushed further.

The diameter of the body 131 is smaller than the diameter of the lid 120 to be fitted.

The size of the lid 120 may be smaller than the diameter of the lid 120 because the size of the lid 120 is expanded due to the pressure generated inside the container 110 when the cooked food is cooked.

The body 131 is expanded on the one surface where the upper and lower tight contact portions 132 and 133 are extended, that is, the inner surface is affected by the pressure generated inside the container 110 during cooking, The shape is deformed such that the thickness becomes thin and the width becomes long.

The pressure generated inside the container 110 makes the body 131 more tightly occupying a wide range of the space of the lid 120.

The outer surface of the body 131 corresponding to the inner surface of the body 131 is deformed due to an increase in pressure generated inside the inner surface of the container 110, 122 is deformed due to the depression of the pressing member 122. [

The internal pressure of the body 131 is extinguished while the container 110 cools down and the internal pressure is released to the outside due to the depression of the pressure button 122 of the handle 121, The deformed shape is contracted and restored to its original shape due to elasticity.

The thickness of the body 131 is formed to be relatively thicker than the thickness of the upper close contact part 132 and the lower close contact part 133. The thickness of the body part 131 can be easily moved back and forth by the push button 122, It is done to such a degree that it is not inconvenient for weak women or the elderly to use.

The upper contact part 132 is integrally formed on the upper part of the body 131 and is in close contact with the lid 120 or the container 110 which is rotatably coupled to the lid 120.

Specifically, the upper tight contact portion 132 prevents the pressure generated inside the container 110 from being discharged to the outside together with the lower tight contact portion 133, And the lower tight contact portion 133 is in close contact with the upper surface of the container 110.

The upper contact portion 132 is formed to be inclined upward from the body 131 and inclined at 130 ° to 150 °.

This is to allow the upper contact portion 132 to be easily and quickly brought into close contact with the upper surface of the lid 120 in a high temperature and high pressure environment.

The upper contact part 132 is deformed due to the increased pressure as the body 131 and is elastically deformed to return to the original shape when the increased pressure is extinguished. (Tilted) upward, so that the end portion is in close contact with the upper surface of the lid 120, that is, it touches.

The upper contact portion 132 is formed to be thinner than the thickness of the body 131 and deformed into a shape that easily expands in the direction of the upper surface of the lid 120 due to an increasing pressure inside the container 110, Further improve.

The inclined slope is deformed by the pressure generated inside the container 110 and is adhered to the upper surface of the lid 120 by only the inclination Unlike the thickness, it is not greatly deformed.

The upper contact portion 132 is closed by the pressure of the pressure button 122 of the handle 121 as the pressure generated inside the container 110 cools as the body 110 cools while the cooking of the body 131 is completed The inner pressure of the container 110 expands to the outside and the deformed inclination (inclination) is restored to the original inclination (slope) due to elasticity.

The upper tight contact portion 132 has a thickness of 0.7 mm to 2.7 mm with reference to a thickness 4 mm of the body 131 of the safety packing 130.

This is to allow the upper contact portion 132 to be easily and quickly brought into close contact with the upper surface of the lid 120 in a high temperature and high pressure environment.

Although the thickness of the upper close contact portion 132 is 0.7 mm to 2.7 mm in the present invention, the thickness of the body 131 is larger than the thickness of the upper close contact portion 132 It may be deformed corresponding to 0.7 mm to 2.7 mm.

The lower contact portion 133 is integrally formed at the lower portion of the body 131 and is in close contact with the lid 120 or the container 110 which is rotatably coupled to the lid 120.

Specifically, the lower close contact portion 133 prevents the pressure generated inside the container 110 from being discharged to the outside together with the upper close contact portion 132. The lower close contact portion 133 is provided with a container And the upper close contact portion 132 is in close contact with the upper surface of the lid 120.

The lower contact portion 133 is formed to be inclined downward from the body 131 and inclined at 130 ° to 150 °.

This is to allow the lower adhesion portion 133 to be easily and quickly brought into close contact with the upper surface of the container 110 in an environment of high temperature and high pressure.

Although the upper and lower contact portions 132 and 133 are illustrated as being inclined at an angle of 130 ° to 150 ° from the body 131 and being easily tilted by an increasing pressure, It can be deformed at other angles as well, which can easily be tilted through pressure.

The lower tight contact portion 133 is deformed due to the increased pressure, such as the body 131 and the upper tight contact portion 132, and is elastically deformable, which is a property of returning to the original shape when the increased pressure is extinguished (Tilted) downward from the body 131, so that the end portion is in close contact with the upper surface of the container 110.

Since the lower adhesion portion 133 is formed to be thinner than the thickness of the body 131 and deformed into a shape that easily spreads in the direction of the upper surface of the container 110 due to the pressure increasing inside the container 110, .

The inclined slope is deformed due to the pressure generated inside the container 110 and is brought into close contact with the upper surface of the container 110. The inclined slope is only deformed, Unlike the thickness, it is not greatly deformed.

The lower tightly connecting part 133 is closed when the container 110 is cooled as time elapses after the cooking of the body 131 or the upper tightly connecting part 132 is completed and the pressure generated inside the container 110 disappears, 122, the inner pressure of the container 110 is discharged to the outside, and the deformed inclination (inclination) is restored to the original inclination (slope) due to elasticity.

The lower tight contact portion 133 has a thickness of 0.7 mm to 2.7 mm with reference to a thickness 4 mm of the body 131 of the safety packing 130.

This is to allow the lower adhesion portion 133 to be easily and quickly brought into close contact with the upper surface of the container 110 in an environment of high temperature and high pressure.

In the pressure cooker 100, the inner pressure of the container 110 increases with the upper and lower contact portions 132 and 133 being in close contact with the lid 120 and the container 110, respectively, Of the environment.

The thickness of the lower tightly connecting part 133 is 0.7 mm to 2.7 mm with respect to the thickness of the body 131 of the body 131. However, It may be deformed corresponding to 0.7 mm to 2.7 mm.

The groove 134 is formed on at least one surface of the body 131 extending from the upper tightening portion 132 and the lower tightening portion 133.

Specifically, at least one groove 134 is formed at the other end corresponding to one end of the body 131 closely attached to the space formed around the inner surface of the lid 120.

The groove 134 can be easily brought into close contact with the upper surface of the lid 120 and the upper surface of the container 110 by the increasing pressure of the upper tight contact portion 132 and the lower tight contact portion 133 inside the container 110 Respectively.

The grooves 134 are formed on the body 131 in order to prevent the upper and lower tightly connecting parts 132 and 133 from being influenced by each other.

It is preferable that the depth of the groove 134 is 0.3 mm to 2.0 mm and the width of the groove 134 is 0.7 mm to 1.5 mm on the basis of the thickness 4 mm of the body 131.

This is because the upper contact portion 132 and the lower contact portion 133 can be easily and quickly brought into close contact with the upper surface of the lid 120 and the upper surface of the container 110 to quickly lead to a high temperature and high pressure environment.

The thickness of the body 131 of the safety packing 130, the depth or width of the groove 134 and the thicknesses of the upper tight contact portion 132 and the lower tight contact portion 133 are technically meaningful.

The safety packing 130 according to the present invention can limit the pressure generated inside the container 130 by the combination of the container 110 and the lid 120 by adjusting the thickness of the body 131 and the depth or width of the groove 134 It is possible to adjust the thickness of the upper close contact portion 132 and the lower close contact portion 133.

This is because it is possible to control the pressure limit in relation to the thickness of the body 131, the depth or width of the groove 134, and the thickness of the upper tight contact portion 132 and the lower tight contact portion 133 described above.

An experimental report on the safety packing for a pressure cooker of the present invention is shown below.

The experimental report of the present invention is to confirm the burst pressure of the safety packing. The safety packing of the product name plate 26 (26 cm in diameter) has a burst pressure of 3.8 kgf / cm 2 (= 372.6 kPa) The maximum pressure).

3 is a perspective view of another embodiment of the safety packing 130a according to the present invention. One side of the body 131a in which the upper tightening part 132a and the lower tightening part 133a are extended is round .

Specifically, one surface of the body 131a in which the upper and lower tight contact portions 132a and 133a are extended is formed in a round shape, and the other surface corresponding to one surface is formed around the inner surface of the lid 120 And is brought into close contact with the space.

The rounded portion formed on one surface of the body 131a can be easily opened to the upper and lower contact portions 132a and 133a at an increased pressure inside the container 110 like the groove 134, Thereby further improving the adhesion between the container 120 and the container 110.

3 is a perspective view of another embodiment of the safety packing 130b according to the present invention in which the groove 134b formed on one surface of the body 131b has an upper tight contact portion 132b and a lower tight contact portion 133b And narrower toward the inside from the extended portion.

This is because the upper and lower contact portions 132b and 133b can be easily opened by the increasing pressure in the container 110 so that the upper and lower contact portions 133b and 133b can be more closely contacted to the lid 120 and the container 110 .

The safety packing 130b of the present invention is formed so that the groove 134b formed in the body 131b becomes narrower toward the inside and the upper packing part 132b and the lower packing part 132b The upper end of the groove 134b may be deformed into a round shape if the upper and lower cohesion parts 132 and 133 can be easily expanded by an increasing pressure. have.

Another experimental report on the safety packing for a pressure cooker of the present invention is shown below.

The experimental report of the present invention is intended to compare the bursting pressure of a conventional packing with a new packing (safety packing of the present invention).

The plate member 18, the plate member 20, the plate member 22, etc. of the product name means 18 cm, 20 cm, 22 cm, and the like, respectively.

The present invention will compare the bursting pressure of a conventional packing with that of a new packing based on the product name plate 18 among various products.

In the case of the existing packing, the flow is large when the burst pressure is 5.3kgf / ㎠ (= 519.7kPa), whereas when the new packing is 3.8kgf / ㎠ (= 372.6kPa)

Therefore, in the case of the packing having the same diameter, the existing packing not only has a high burst pressure but also a large flow at the time of bursting, while the new packing has a difference in that the bursting pressure is low and the flow is slightly generated at the time of bursting.

In conclusion, new packings have lower explosion pressure than conventional packings, thus ensuring more safety than conventional packings.

As the diameter of the existing packing increases, the thickness of the packing increases, and the bursting pressure becomes higher.

The novel packing (safety packing) of the present invention may have a larger diameter, but the thickness of the body of the safety packing, the depth or width of the groove, and the thickness of the upper and lower tight contact portions remain unchanged. As a result, the burst pressure of the new packing becomes much lower than the existing packed burst pressure.

The safety packing 130 of the present invention can be elastically deformed so that the internal pressure of the container 110 can be easily discharged to secure safety, and the safety packing 130 can be easily tilted by the internal pressure generated at the time of cooking to further improve the close contact state.

The safety packing 130 that is easily tilted can be cleanly cleaned, thereby maintaining a clean sanitary condition continuously.

The safety packing 130 can be easily moved forward and backward by the push button 122 provided in the pressure cooker 100 when the cooking is completed and thus the strength of the hand such as a hand force It provides convenience for the elderly to use.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And such variations and modifications are intended to fall within the scope of the appended claims.

10, 100: Pressure cooker
11, 110: container
12, 120: lid
12a: Pressure regulating valve
12b: Safety valve
12c, 121: handle
12d, 122: pressure button
13, 130: Safety packing (rubber packing)
13a, 131: body
13b and 132:
13c and 133:
134: Home

Claims (9)

A safety packing for a pressure cooker, which is fitted in a space formed inside a lid of a pressure cooker used for cooking cooked foods such as rice,
The safety packing
A ring-shaped body which is elastically deformable,
An upper tight contact portion which is formed on the upper portion of the body and is in tight contact with the lid or in contact with the container rotatably coupled to the lid,
A lower tight contact portion which is formed on the lower portion of the body and is in tight contact with the lid or in contact with the container which is rotatably coupled to the lid,
And a groove formed on at least one surface of the body on which the upper close portion and the lower close portion are extended. The method according to claim 1,
The safety packing is capable of controlling the pressure generated in the sealed inside by the combination of the container and the lid through the thickness of the body, the depth or width of the groove, and the thickness of the upper and lower tight contact portions Features Safety packing for pressure cooker. The method according to claim 1,
Wherein the safety packing has a depth of 0.3 mm to 2.0 mm and a width of the groove of 0.7 mm to 1.5 mm based on a thickness of the body of 4 mm. The method according to claim 1,
Wherein the safety packing has a thickness of about 4 mm and a thickness of the upper and lower tight contact portions is about 0.7 mm to about 2.7 mm. The method according to claim 1,
Wherein the thickness of the body is thicker than the thickness of the upper close contact portion and the lower close contact portion. The method according to claim 1,
Wherein the upper tight contact portion and the lower tight contact portion are inclined upwardly and downwardly from the body, respectively. The method according to claim 6,
Wherein the upper tight contact portion and the lower tight contact portion are inclined at an angle of 130 ° to 150 ° with respect to the upper direction and the lower direction from the body, respectively. The method according to claim 1,
Wherein one surface of the body extended from the upper tightly coupled portion and the lower tightly coupled portion is formed in a round shape. The method according to claim 1,
Wherein the groove formed on one surface of the body is formed to become narrower toward the inside in a portion extended from the upper close portion and the lower close portion.

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