KR101709054B1 - Hinge for holding door - Google Patents

Abstract

The present invention relates to a hinge for a folding door. A first frame having a first coupling gear is connected to a second frame having a second coupling gear by a gear connection method. A first groove having a semicircular groove of a ring shape is formed on a first axial circumference formed on the upper surface of the first frame. A second groove having the semicircular groove of the ring shape is formed on a second axial circumference formed on the upper surface of the second frame. A first stopper and a second stopper are formed in a first groove and a second groove. A half bow of the outer circumference of a first spring and a second spring is embedded in the first groove and the second groove. A joint bar has the first groove and the first stopper on one side of a plate shape having a first hole and a second hole, a third groove and a third stopper symmetrical to and corresponding to the second groove and the second stopper, and a fourth groove and a fourth stopper. The joint bar is connected to a first shaft and a second shaft formed in the first frame and the second frame. The first door and the second door, which are folded, can be spread at the angle of 180 degrees by elasticity of the first spring and the second spring.

Description

[0001] HINGE FOR HOLDING DOOR [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hinge for a folding door, and more particularly, to a folding door hinge for easily folding a folded first door and a second door.

Generally, the folding door hinge is mounted between the door and the door so that the door can be folded in both directions with respect to the hinge.

As the internal structure of the hinge becomes complicated, the thickness of the hinge becomes thick, and troubles frequently occur.

An invention such as Korean Patent Registration No. 10-1125490 (titled invention: hinges and doors) has been proposed as a conventional technique.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hinge for a folding door having a small thickness and high rigidity.

In order to solve the above-described problems, the present invention provides a folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type folding type, CLAIMS 1. A door hinge comprising: a first frame having a plate-like one side formed in a semicircular shape; A first fastening gear having a plurality of projections on a semicircular outer circumferential surface of the first frame; A first axis formed on the upper surface of the first frame so as to protrude from the center of the semicircular shape; A first groove formed in the upper surface of the first frame so that a semicircular groove is formed in a ring shape around the first axis; A first stopper disposed in the first groove at a position that is in line with the first door and protruding to a height that is horizontally aligned with the first frame upper surface; A first spring in which one side and the other side of the coil-shaped elastic body are in contact with the first stopper while the half of the outer periphery of the coil-like elastic body is embedded in the first groove; A second frame in which one side of the plate shape is formed in a semicircular shape; A second fastening gear having a plurality of projections formed on a semicircular outer circumferential surface of the second frame so as to be connected to the first fastening gear in a gear engagement manner; A second shaft formed on the upper surface of the second frame so as to protrude from the center of the semicircular shape; A second groove formed on the upper surface of the second frame in a ring shape along the second axis; A second stopper disposed in the second groove at a position that is in line with the second door and protruding to a height that is level with the second frame upper surface; A second spring in which one side and the other side of the coil-shaped elastic body are in contact with the second stopper while the half of the outer periphery of the coil-like elastic body is embedded in the second groove; A joint bar in which a first hole and a second hole are formed such that a plate shape is inserted into the first shaft and the second shaft; A third groove formed on a surface of the joint bar in contact with the first frame, the third groove being symmetrical with the first groove and corresponding to the first groove; A third stopper formed in the third groove in a position symmetrical with the first stopper and corresponding to the first stopper; A fourth groove formed in one surface of the joint bar that is in symmetry with the second groove and in a corresponding shape on one surface of the joint bar in contact with the second frame and a fourth groove formed in a position symmetrical to the second stopper, The hinge for a folding door including the fourth stopper formed thereon can be provided.

The hinge for the folding door may include a first engaging projection insertion member formed at the center of the upper surface of the first shaft and having a groove formed at the center of the wing column; A second engaging projection insertion member formed at the center of the upper surface of the second shaft and having a groove formed at the center of the worm shaft; And a second fixing disk having a first fixing disk having a projection-like first coupling protrusion formed at the center of the lower surface of the disk-like shape and a second coupling protrusion having a projection-like shape formed at the center of the lower surface of the disk- And the second fixing plate are provided on the first coupling projection insertion member and the second coupling projection insertion member so as to prevent the separation of the coupling bar mounted on the first shaft and the second shaft, Respectively.

The hinge for the folding door has a first bearing insertion groove and a second bearing insertion groove formed in a ring shape on the surfaces of the first fixing disk and the second fixing disk which are in contact with the upper surface of the joint bar, A plurality of ball bearings may be incorporated in the one bearing insertion groove and the second bearing insertion groove.

The hinge for the folding door has a third bearing insertion groove and a fourth bearing insertion groove formed in a ring shape on an upper surface of the first frame and the second frame which are in contact with a lower surface of the joint bar, A plurality of ball bearings may be incorporated in the bearing insertion groove and the fourth bearing insertion groove.

The hinge for the folding door further includes a first guide member and a second guide member formed on the lower surface of the first frame and the second frame in a shape corresponding to the lower surface shape of the first frame and the second frame can do.

The hinge for the folding door may have a disk-shaped outer peripheral surface formed in the same shape as the inner peripheral surface of the first groove and the third groove, and the first groove and the third groove Wherein the first and second guide plates and the disk-shaped outer peripheral surface are formed in the same shape as the inner circumferential surfaces of the second and fourth grooves, And a third guide plate and a fourth guide plate disposed between the second groove and the fourth groove.

The hinge for the folding door may include a plurality of first fixing bars formed on the other side of the first frame that are in contact with the first door such that the bar is protruded so that the first door is inserted into the first frame, And a plurality of second fixing bars formed on the other side of the second frame that are in contact with the second door such that a bar shape protrudes so that the second door is inserted into the second frame.

The hinge for the folding door according to the embodiment of the present invention is configured such that the first spring and the second spring are horizontally disposed so that the material cost is reduced while the thickness is reduced and the restoration speed in which the door is restored horizontally after folding .

Further, the hinge for a folding door according to the embodiment of the present invention is light and has high strength, so that the fastening operation for connecting to the door is easy, and the failure rate is low.

1 is a perspective view showing a hinge for a folding door according to a first embodiment of the present invention;
Fig. 2 is a bottom view of the hinge for the folding door shown in Fig. 1. Fig.
3 is an exploded perspective view illustrating the hinge for the folding door shown in Fig. 1; Fig.
Fig. 4 is an exemplary view showing the operation of the hinge for the folding door shown in Fig. 1. Fig.
5 is a perspective view illustrating a hinge for a folding door according to a second embodiment of the present invention.
FIG. 6 is a perspective view showing the first fixed disk and the second fixed disk shown in FIG. 5; FIG.
FIG. 7 is an exploded perspective view of the folding door hinge shown in FIG. 5; FIG.

Hereinafter, the description of the present invention with reference to the drawings is not limited to a specific embodiment, and various transformations can be applied and various embodiments can be made. It is to be understood that the following description covers all changes, equivalents, and alternatives falling within the spirit and scope of the present invention.

In the following description, the terms first, second, and the like are used to describe various components and are not limited to their own meaning, and are used only for the purpose of distinguishing one component from another component.

Like reference numerals used throughout the specification denote like elements.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the terms " comprising, "" comprising, "or" having ", and the like are intended to designate the presence of stated features, integers, And should not be construed to preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a hinge for a folding door according to a first embodiment of the present invention, FIG. 2 is a bottom view showing a hinge for a folding door shown in FIG. 1, FIG. 4 is an exemplary view showing the operation of the hinge for the folding door shown in FIG. 1; FIG.

1 to 4, the folding door hinge 1 is mounted between a first door D1 and a second door D2 to rotate the first door D1 and the second door D2 at 180 ° Can be unfolded. The folding door hinge 1 can fold the first door D1 and the second door D2 in both directions. The folding door hinge 1 may be mounted on the upper and lower sides of the first door D1 and the second door D2. The folding door hinge 1 includes a first frame 10, a first spring 20, a second frame 30, a second spring 40, a connecting bar 50, a first fixing disk 60, And a second fixed disk 70.

The first frame 10 may be formed in a plate shape. One side of the first frame 10 may be formed in a semicircular shape. The first frame 10 includes a first fastening gear 11, a first shaft 12, a first fastening bar 13, a first groove 14, a first stopper 15, (17).

The first fastening gear 11 is a plurality of protrusions formed on the outer peripheral surface of one side of the first frame 10 formed in a semicircular shape.

The first shaft 12 is a shaft that protrudes with respect to the semicircular center of the upper surface of the first frame 10. The first shaft 12 may include a first engaging projection insertion member 18 so that a first engaging projection 62 is inserted and fixed, which will be described later.

The first coupling projection insertion member 18 may be formed with a groove in the center of the cylindrical shape so that the first coupling projection 62 is inserted. The first coupling projection insertion member 18 may be formed at a position that is the center of the first shaft 12.

The first fixing bar 13 includes a plurality of bars formed to protrude from the other side of the first frame 10 in contact with the first door D1 so that the first door D1 is inserted into the first frame 10. [ bar). The first fixing bar 13 may protrude from both sides of the first frame 10 in the direction of the first door D1.

The first groove 14 is a groove having a semicircular groove formed in a ring shape on the upper surface of the first frame 10 around the first shaft 12.

The first stopper 15 may be formed in the first groove 14 at a position that is in line with the first door D1. The first stopper 15 may be formed to have a height from the first groove 14 to the upper surface of the first frame 10.

Here, the protruded one surface of the first stopper 15 may be horizontally aligned with the upper surface of the first frame 10. [

The first stopper 15 may be formed integrally with the first frame 10.

1 and 5, the first screw insertion hole 17 has a first door D1 or a first guide member 80 mounted on the lower surface of the first frame 10, Is a hole penetrating from the upper surface to the lower surface of the first frame 10 so as to be screwed to the first frame 10. At least one first screw insertion hole (17) may be formed in the first frame (10).

Here, a screw head support portion protruding from the inner wall at a predetermined distance and capable of supporting the head of the screw may be formed in the inner wall of the hole of the first screw insertion hole 17.

The first frame 10 may have a stepped multi-step structure in which the first screw insertion hole 17 and the first fixing bar 13 are formed so that the torsional rigidity is increased.

The first spring 20 is a spring formed of a coil-shaped elastic body. The first spring 20 may be embedded in the first groove 14 and the third groove 53 so that one side and the other side contact the first stopper 15 and the third stopper 54.

Here, one side and the other side of the first spring 20 can be brought into contact with the first stopper 15, and the other half of the outer circumference can be brought into contact with the third stopper 54.

The first spring 20 may have a diameter that allows one half of the outer circumference to be embedded in the first groove 14. 4, when the first frame 10 is rotated in one direction by an external force, the first spring 20 is rotated in the first stopper 15 in the direction in which the first frame 10 is rotated One side of the contacted first spring 20 moves in the rotating direction of the first frame 10 and the other side of the first spring 20 can be supported in the third stopper 54. [

Therefore, when the first spring 10 is not subjected to an external force, the elasticity of the first spring 20 is increased and the first stopper 15 is moved to the position of the third stopper 54 by elastic force Can be moved.

The second frame 30 may be formed in a plate shape. One side of the second frame 30 may be formed in a semicircular shape. The second frame 30 includes a second fastening gear 31, a second shaft 32, a second fastening bar 33, a second groove 34, a second stopper 35, (37).

The second fastening gear 31 is a plurality of projections formed on the outer circumferential surface of the second frame 30 formed in a semicircular shape on one side.

The second shaft 32 is a shaft that protrudes from the center of the semicircular shape of the upper surface of the second frame 30. The second shaft 32 may include a second engaging projection insertion member 38 so that a second engaging projection 72 is inserted and fixed, which will be described later.

The second coupling projection insertion member 38 may be formed with a groove in the center of the cylindrical shape so that the second coupling projection 72 is inserted. The second coupling projection insertion member 38 may be formed at a position that is the center of the second shaft 32.

The second fixing bar 33 is provided with a plurality of bars (not shown) formed on the other side of the second frame 30 to be in contact with the second door D2 so that the second door D2 is inserted into the second frame 30. [ bar). The second fixing bars 33 may protrude from both sides of the second frame 30 in the direction of the second door D2.

The second groove 34 is a groove having a semicircular groove formed in a ring shape on the upper surface of the second frame 30 around the second shaft 32.

The second stopper 35 may be formed in the second groove 34 at a position that is in line with the second door D2. The second stopper 35 may be formed to have a height from the second groove 34 to the upper surface of the second frame 30.

Here, the protruded one surface of the second stopper 35 may be horizontally aligned with the upper surface of the second frame 30. [

The second stopper 35 may be formed integrally with the second frame 30.

The second screw insertion hole 37 is formed in the second frame 30 so that the second door D2 or the second guide member 90 mounted on the lower surface of the second frame 30 is inserted into the second frame 30, The upper surface of the second frame 30 and the lower surface thereof. At least one second screw insertion hole 37 may be formed in the second frame 30.

Here, a screw head support portion protruding from the inner wall at a predetermined distance and capable of supporting the head of the screw may be formed in the inner wall of the hole of the second screw insertion hole 37.

The second frame 30 may have a stepped multistage structure in which the second screw insertion hole 37 and the second fixing bar 33 are formed so as to increase the torsional rigidity.

The second spring 40 is a spring formed of a coil-shaped elastic body. The second spring 40 may be embedded in the second groove 34 and the fourth groove 55 so that one side and the other side of the second spring 40 contact the second stopper 35 and the fourth stopper 56.

Here, one side and the other side of the second spring 40 can be brought into contact with the second stopper 35, and the other half of the outer periphery can be brought into contact with the fourth stopper 56.

The second spring 40 may be formed to have a diameter that allows the half of the outer circumference to be embedded in the second groove 34. 4, when the second frame 30 is rotated in one direction by an external force, the second spring 40 is rotated in the second stopper 35 in the direction in which the second frame 30 is rotated One side of the contacted second spring 40 moves in the rotational direction of the second frame 40 and the other side of the second spring 40 can be supported in the fourth stopper 56. [

Therefore, the elastic force of the second spring 40 is increased by the restoring force, and when the second frame 30 is not subjected to external force, the second stopper 35 is moved to the position of the fourth stopper 56 by elastic force Can be moved.

The joint bars 50 may be formed in a semicircular shape on both sides of a rectangular plate shape. The joint bar 50 includes a first hole 51, a second hole 52, a third groove 53, a third stopper 54, a fourth groove 55 and a fourth stopper 56 .

The first hole 51 is a hole through which the first shaft 12 can be inserted.

The second hole 52 is a hole into which the second shaft 32 can be inserted.

The third groove 53 is a groove formed in a position and a corresponding shape symmetrical with the first groove 14 on one surface of the joint bar 50 contacting the first frame 10.

The third stopper 54 may be formed in the third groove in a position symmetrical to the first stopper 15 and in a corresponding shape.

The fourth groove 55 is a groove formed in a position and a corresponding shape symmetrical with the second groove 34 on one surface of the joint bar 50 contacting the second frame 30. [

The fourth stopper 56 may be formed in the fourth groove in a position symmetrical to the second stopper 35 and in a corresponding shape.

The first fixing disk 60 can prevent the detachment of the joint bar 50 mounted on the first shaft 12. The first fixed disk 60 may be formed in a disk shape. The first fixing disk 60 may include a first engaging projection 62 to be fixed to the first engaging projection inserting member 18.

The first engaging projection 62 may be formed to protrude from the lower surface of the joint bar 50 so as to be inserted and fixed in the first engaging projection inserting member 18.

The second fixing disk 70 can prevent the separation of the joint bar 50 mounted on the second shaft 32. The second fixed disk 70 may be formed in a disc shape. The second fixing disk 70 may include a second engaging projection 72 to be fixed to the second engaging projection inserting member 38.

The second engaging projection 72 may be formed to protrude from the lower surface of the joint bar 50 so as to be inserted and fixed in the second engaging projection insertion member 38.

FIG. 5 is a perspective view showing a hinge for a folding door according to a second embodiment of the present invention, FIG. 6 is a perspective view showing the first fixing plate and the second fixing plate shown in FIG. 5, Fig. 3 is an exploded perspective view of the folding door hinge shown in Fig.

The hinge for the folding door according to the second embodiment of the present invention shown in Figs. 5 to 7 is different from that of Figs. 1 to 4 in that the hinge for the folding door shown in Figs. 1 to 5 has first and second guides A first bearing insertion groove and a second bearing insertion groove into which ball bearings can be inserted are formed on the surfaces of the first to fourth guide plates, the first fixed plate, and the second fixed plate, And a third bearing insertion groove and a fourth bearing insertion groove into which the ball bearing can be inserted, are formed on the upper surface of the cylinder block. Therefore, the same reference numerals are given to the same constituent elements, and redundant description of the same constituent elements will be omitted, and the added constituent elements will be mainly described.

5 to 7, the folding door hinge 1 may include a first guide member 80 and a second guide member 90. [

The first guide member (80) and the second guide member (90) may be formed in a semicircular shape on one side facing each other.

Therefore, even when the first door D1 and the second door D2 are folded in the one direction or the other direction by the folding door hinge 1, the airtightness can be maintained while keeping a constant gap or contact in the folding direction.

The first guide member 80 and the second guide member 90 may be made of rubber, plastic, or sponge.

The first guide member 80 and the second guide member 90 are formed of a semicylindrical material of a soft material and the magnets are contained in the semicircular shape of the first guide member 80 and the second guide member 90, (80) and the second guide member (90) are adhered to each other.

The first guide member 80 and the second guide member 90 may have a plurality of hair-like strips formed on a surface facing each other to enhance the airtightness.

The first fixed disk 60 may include a first bearing insertion groove 61 so that a ball bearing B is embedded in a surface contacting the upper surface of the joint bar 50.

The first bearing insertion groove 61 may have a semicircular groove formed in a ring shape around the first hole 51.

The second fixed disk 70 may include a second bearing insertion groove 71 so that the ball bearing B is embedded in the surface that contacts the upper surface of the joint bar 50.

The second bearing insertion groove 71 may have a semicircular groove formed in a ring shape around the second hole 52.

The first frame 10 may include a third bearing insertion groove 16 so that the ball bearing B is embedded in the upper surface contacting the lower surface of the joint bar 50.

The third bearing insertion groove 16 may have a semicircular groove formed in a ring shape around the first shaft 12.

The second frame 30 may include a fourth bearing insertion groove 36 such that the ball bearing B is embedded in the upper surface contacting the lower surface of the joint bar 50.

The fourth bearing insertion groove 36 may have a semicircular groove formed in the shape of a ring around the second axis 32.

The first guide plate 100 may be disposed between the first groove 14 and the third groove 53 so as to be in contact with one side of the first spring 20. The first guide plate 100 can transmit the external force of the first stopper 15 to one side of the first spring 20 when the first frame 10 rotates in one direction. Accordingly, when the external force of the first stopper 15 is applied to only one half of the outer periphery of the first spring 20, the first spring 20 is deformed or the first stopper 15 and the third groove 53 It is possible to prevent the first spring 20 from being inserted.

The second guide plate 110 may be disposed between the first groove 14 and the third groove 53 so as to be in contact with the other side of the first spring 20. The second guide plate 110 can transmit the external force of the first stopper 15 to the other side of the first spring 20 when the first frame 10 rotates in the other direction. Accordingly, when the external force of the first stopper 15 is applied to only one half of the outer periphery of the first spring 20, the first spring 20 is deformed or the first stopper 15 and the third groove 53 It is possible to prevent the first spring 20 from being inserted.

The third guide plate 120 may be disposed between the second groove 34 and the fourth groove 55 so as to be in contact with one side of the second spring 40. The third guide plate 120 can transmit the external force of the second stopper 35 to one side of the second spring 40 when the second frame 30 rotates in one direction. Therefore, when the external force of the second stopper 35 is applied to only the half of the outer circumference of the second spring 40, the second spring 40 is deformed or the second stopper 35 and the fourth groove 55 It is possible to prevent the second spring 40 from being inserted.

The fourth guide plate 130 may be disposed between the second groove 34 and the fourth groove 55 so as to be in contact with the other side of the second spring 40. The fourth guide plate 130 can transmit the external force of the second stopper 35 to the other side of the second spring 40 when the second frame 30 rotates in the other direction. Therefore, when the external force of the second stopper 35 is applied to only the half of the outer circumference of the second spring 40, the second spring 40 is deformed or the second stopper 35 and the fourth groove 55 It is possible to prevent the second spring 40 from being inserted.

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, It will be clear to the person.

1: Folding door hinge
10: First frame
11: first fastening gear
12: First axis
13: first fixed bar
14: First home
15: 1st stop
16: third bearing insertion groove
17: first screw insertion hole
18: first engaging projection insertion member
20: first spring
30: Second frame
31: second fastening gear
32: 2nd axis
33: second fixed bar
34: 2nd home
35: second stop
36: fourth bearing insertion groove
37: second screw insertion hole
38: second engaging projection insertion member
40: second spring
50: Connecting bars
51: first hole
52: Second hole
53: Third Home
54: Third stop
55: Fourth Home
56: Fourth stop
60: first fixed disk
61: first bearing insertion groove
62: first engaging projection
70: second fixed disk
71: second bearing insertion groove
72: second engaging projection
80: first guide member
90: second guide member
100: first guide plate
110: second guide plate
120: Third guide plate
130: fourth guide plate

Claims (7)

A hinge for a folding door mounted between a first door and a second door to unfold a folded first door and a second door such that the first door and the second door are folded in both directions,
A first frame having one side of a plate shape formed in a semicircular shape;
A first fastening gear having a plurality of projections on a semicircular outer circumferential surface of the first frame;
A first axis formed on the upper surface of the first frame so as to protrude from the center of the semicircular shape;
A first groove formed in the upper surface of the first frame so that a semicircular groove is formed in a ring shape around the first axis;
A first stopper disposed in the first groove at a position that is in line with the first door and protruding to a height that is horizontally aligned with the first frame upper surface;
A first spring in which one side and the other side of the coil-shaped elastic body are in contact with the first stopper while the half of the outer periphery of the coil-like elastic body is embedded in the first groove;
A second frame in which one side of the plate shape is formed in a semicircular shape;
A second fastening gear having a plurality of projections formed on a semicircular outer circumferential surface of the second frame so as to be connected to the first fastening gear in a gear engagement manner;
A second shaft formed on the upper surface of the second frame so as to protrude from the center of the semicircular shape;
A second groove formed on the upper surface of the second frame in a ring shape along the second axis;
A second stopper disposed in the second groove at a position that is in line with the second door and protruding to a height that is level with the second frame upper surface;
A second spring in which one side and the other side of the coil-shaped elastic body are in contact with the second stopper while the half of the outer periphery of the coil-like elastic body is embedded in the second groove;
A joint bar in which a first hole and a second hole are formed such that a plate shape is inserted into the first shaft and the second shaft;
A third groove formed on a surface of the joint bar in contact with the first frame, the third groove being symmetrical with the first groove and corresponding to the first groove;
A third stopper formed in the third groove in a position symmetrical with the first stopper and corresponding to the first stopper;
A fourth groove formed at one surface of the joint bar in contact with the second frame and symmetrical with the second groove and formed in a corresponding shape;
And a fourth stop formed in the fourth groove in a position symmetrical to the second stopper and in a corresponding shape.
The method according to claim 1,
A first engaging projection insertion member formed at the center of the upper surface of the first shaft and having a groove formed at the center of the worm shaft;
A second engaging projection insertion member formed at the center of the upper surface of the second shaft and having a groove formed at the center of the worm shaft;
A first stationary disk having a first engaging projection in the shape of a projection at the center of the lower surface of the disk-
And a second fixing disk having a projection-shaped second coupling protrusion formed at the center of the lower surface of the disk-
The first fixing plate and the second fixing plate
The first engaging projection and the second engaging projection are respectively inserted and fixed to the first engaging projection insertion member and the second engaging projection insertion member so as to prevent the separation of the joint bar mounted on the first and second shafts Features a folding door hinge.
3. The method of claim 2,
A first bearing insertion groove and a second bearing insertion groove are formed in a ring shape on the surfaces of the first fixed disk and the second fixed disk that are in contact with the upper surface of the joint bar, And a plurality of ball bearings are embedded in the insertion groove.
The method of claim 3,
A third bearing insertion groove and a fourth bearing insertion groove are formed in a ring shape on an upper surface of the first frame and the second frame which are in contact with a lower surface of the joint bar and the third bearing insertion groove and the fourth bearing insertion groove, And a plurality of ball bearings are embedded in the groove.
The method according to claim 1,
And a first guide member and a second guide member formed on the lower surface of the first frame and the lower surface of the second frame in a shape corresponding to a lower surface shape of the first frame and the second frame.
The method according to claim 1,
A first guide plate disposed between the first groove and the third groove so as to be in contact with one side of the first spring and the other side of the first spring, And a second guide plate
A third guide plate disposed between the second groove and the fourth groove so as to be in contact with one side and the other side of the second spring, the outer peripheral surface of the disk-like shape being formed in the same shape as the inner peripheral surface of the second groove and the fourth groove, And a fourth guide plate.
The method according to claim 1,
A plurality of first fixing bars formed on the other side of the first frame that are in contact with the first door such that a bar shape protrudes so that the first door is inserted into the first frame;
And a plurality of second fixing bars protruding in a bar shape on the other side of the second frame in contact with the second door so that the second door is inserted into the second frame.

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