JP2002136389A - Chair with backrest - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve breaking strength of a downward cylinder part in a backrest in a chain having the downward cylinder part arranged in the backrest made of a synthetic resin and fitted into a back support column made of a steel pipe. SOLUTION: The upper end 4a of the back support column 4 is cut out into a tapered shape or into a circular arc. Even if a backrest load is applied, the upper end 4a of the back support column 4 is not bitten by the downward cylinder part 6a, so that breakage caused by the load concentrated in a part of the downward cylinder part 6a can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

 The present invention relates to a chair with a backrest.

[0001]

2. Description of the Related Art There is a chair in which a skeleton is formed of a metal pipe and a seat and a backrest are attached to the frame, and this chair is widely used in various venues for meetings and the like. It can be stacked).

As one type of this type of chair, a pair of right and left back struts are erected from the rear of a seat body, and a downwardly-opening cylindrical portion is provided on both left and right sides of a synthetic resin backrest.
There is a structure in which the downwardly directed cylindrical portion is fitted to a back support (for example, Japanese Patent Application Laid-Open Nos. 8-228882 and 8-22888).
No. 3).

[0003]

In the chair having this structure, the backrest load acting backward by the seated person leaning on the backrest is supported by the back column via the downwardly-facing tubular portion of the backrest.

[0004] In this case, since the back support is made of a metal pipe, there is little problem in strength. However, since the back support is made of a synthetic resin, there is a concern that the downward cylindrical portion may be broken when used for many years. .

[0005] The inventors of the present invention have conducted research and experiments on this point, and found that, in the conventional chair, in particular, the front side of the portion of the downwardly-facing tubular portion that contacts the upper end of the back column is pierced by the back column. The phenomenon of breaking was observed.
This is elucidated as follows.

That is, first, in the case of a chair in which a downwardly-facing tubular portion provided on a backrest is fitted into a metal back support standing upright at the rear of the seat, the upper end of the back support is centered on the backrest due to the backrest load. Then, a moment is generated that causes the player to lean backward. For this reason, in the downward-facing cylinder portion of the backrest, the load tends to be concentrated on the front portion at the upper end portion of the back support and the rear portion at the lower end portion of the downward cylinder portion.

[0007] Conventionally, the upper end of the pipe-made back strut is still cut, and a sharp edge is formed between the upper end surface and the outer peripheral surface. It was found that a phenomenon of biting occurred, and the downwardly facing cylindrical portion was easily broken.

It is considered that the reason why the upper end of the back strut is kept cut is that the upper end of the back strut is hidden by the downwardly-facing tubular portion of the backrest, and there is no problem in appearance and safety.

The present invention has been made based on such findings, and in a chair in which a downwardly-facing tubular portion of a backrest is fitted into a back column, it is difficult to break the downwardly-facing tubular portion of the backrest. The purpose is to improve durability.

[0010]

SUMMARY OF THE INVENTION Accordingly, the present invention relates to a chair having the above-described structure, in which one or both of the back column and the downward cylindrical portion of the backrest are provided. A stress concentration suppressing means or reinforcing means for increasing the breaking strength of a portion which intensively contacts the back support when a back load is applied is formed.

In this case, in the second aspect, as the stress concentration suppressing means, the upper end of the back column is formed in a tapered shape or an arc shape, or a cushioning protective cap is fitted into the back column.

[0012]

According to the present invention, in the case of a chair having a structure in which a downwardly directed tubular portion formed on a backrest is fitted to a back support, when a seated person leans on the backrest, the load acts as a moment on the downwardly directed tubular portion. That cannot be avoided.

However, in the present invention, even if the backrest load is partially applied to the downward cylinder, the breaking strength of the downward cylinder can be increased by the stress concentration suppressing means or the reinforcing means. For this reason, the durability of the chair can be improved.

In the second aspect, if the upper end of the back support is formed in a tapered shape or an arc shape, very simple processing is sufficient.
There is an advantage that cost increase can be avoided.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings.

(1) First Embodiment (FIGS. 1 to 4) FIGS. 1 to 4 show a first embodiment. 1 is an overall schematic perspective view, FIG. 2 is an exploded perspective view, FIG. 3A is a right side view, and FIG. 3B is a partial rear view.

[0017] The chair comprises a seat frame 1 made of a steel pipe and having a substantially quadrangular shape in a plan view, a pair of left and right leg frames 2 supporting left and right sides of the seat frame 1, and a left and right leg frame 2 connected at an upper portion thereof. A reinforcing frame 3, a set of two back columns 4 erected at the left and right rear portions of the seat frame 1,
A seat 5 and a backrest 6 with a cushion 7 are provided.

The left and right horizontal portions 1c of the seat frame 1, the leg frame 2, and the back column 4 are continuous with each other.
The left and right horizontal portions 1 c and the leg frame 2 are connected to the front and rear horizontal portions 1 a and 1 b of the seat frame 1 and the reinforcing frame 3. The connection point between the left and right horizontal portion 1c and the front horizontal portion 1a of the seat frame 1 is a triangular bracket 8 in plan view.
It is reinforced with.

The backrest 6 is made of a synthetic resin such as polypropylene, and has a downwardly directed cylindrical portion 6a fitted on the back support column 4 integrally formed on both left and right sides thereof. The downwardly facing cylindrical portion 6a is fixed to the back column 4 with screws 9.

In this embodiment, one screw 9 is used to
Although the two back posts 4 are fixed, if two back posts 4 are also fixed, for example, a screw 9 is inserted into one back post 4 from the front, and the other from the rear. If the insertion holes of the screws 9 are eliminated by inserting the screws 9 or changing the height at which the screws 9 are inserted in the right and left columns 4, a decrease in the strength of the downward cylindrical portion 6 a can be suppressed. .

At the lower end of the leg frame 2,
0, 11 and the connecting tool 12 are attached. Reference numeral 13 in FIG.
Is a seat bracket for attaching the seat body 5, and reference numeral 14 is a cover for covering the seat bracket 13 from below.

[0022] Mounting Structure of Backrest The downwardly-facing cylindrical portion 6a of the backrest 6 is formed in an oval cross section, and the hollow hole 15 inside is also formed in an oval shape.

The hollow hole 15 extends upward while reducing its sectional area. This is mainly because the thickness of the backrest 6 is equalized in each portion, thereby eliminating sink marks during molding and equalizing flexural deformation.

FIG. 4A is a cross-sectional view showing the fitted state of the back column 4 and the downwardly directed cylindrical portion 6a, and FIG. 4B is a diagram of only the back column 4, as shown in these figures. The upper end 4a of each back column 4 is cut into a chamfered shape and is tapered. Although the figure shows a state in which the back column 4 and the downward cylindrical portion 6a are in close contact with each other, in practice, a slight clearance is often provided between them.

When a person's body pressure (backrest load) acts on the backrest 6, a moment is generated in the downwardly-facing cylindrical portion 6a so as to tilt it backward. And, the downward cylinder 6a
Is slightly elastically deformed, so that the downward cylindrical portion 6a is
Tend to intensively hit the upper end 4a of the.

However, in the present embodiment, since the upper end 4a of each back support 4 is tapered, the back-downward cylindrical portion 6a
Among them, it is possible to suppress the concentration of stress on the portion that comes into contact with the upper end 4a of the back column 4 and to remarkably improve the breaking strength of the downward cylindrical portion 6a.

(2) Another Embodiment (FIG. 5) FIG. 5 shows another embodiment. In (A), the upper end of the back column 4 is formed in an arc shape.

In (B), only the front portion of the upper end 4a of the back support 4 is formed as a chamfered inclined surface. The downward cylindrical portion 6a of the backrest 6 can easily hit the front end portion of the upper end portion 4a of the back support 4 due to the backrest load, so that the same effect can be obtained even in the mode shown in FIG.

In (C) and (D), the protective cap 16 is fitted into the back column 4 from above. The protective cap has a moderate elasticity like rubber. In (D), the protective cap 15 is formed symmetrically as a whole.
Is formed in a shape inclined forward.

If there is a gap between the inner surface of the downwardly directed cylindrical portion 6a and the outer surface of the back column 4, as shown by a dashed line in FIG. 17 may be covered. It is also possible to cut the upper part of the back support 4 into a small diameter and cover the small diameter part with the cap 17.

By the way, due to the backrest load, the lower end of the downwardly directed cylindrical portion 6a has a tendency for its rear portion to strongly hit the back column 4. Therefore, in the examples shown in (E) and (F), the thick reinforcing portion 18 is formed only at the rear portion of the lower end of the downwardly directed tubular portion 6a.

As shown by the dashed line in (C), a thick reinforcing portion 18 may be formed at a portion of the front surface of the downwardly directed cylindrical portion 6a corresponding to the upper end of the back support column 4. Further, the reinforcing portion means may be a rib extending in a vertical direction.

(3) Others The present invention is not limited to the above embodiment, but can be embodied in various ways. For example, as a reinforcing means, a metal reinforcing cylinder may be embedded inside the downward cylindrical portion by insert molding or the like.

As the stress suppressing means, it is also possible to form an extremely small number of slits at the top of the pipe-made back strut so that the upper end of the back strut is elastically deformed.

The downward cylinder is not necessarily formed integrally with the backrest. The main body of the backrest and the downward cylinder may be manufactured separately and connected together by some means. is there.

[Brief description of the drawings]

FIG. 1 is a perspective view of a chair according to a first embodiment.

FIG. 2 is an exploded perspective view of a chair.

3A is a right side view, and FIG. 3B is a partial front view.

FIG. 4A is a cross-sectional view, and FIG. 4B is a view showing only a back support.

FIG. 5 is a diagram showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Seat frame 4 Back support 4a Upper end of back support 5 Seat 6 Backrest 6a Downward cylindrical part 16,17 Protective cap 18 Thick reinforcing part

Claims (2)

[Claims] 1. A chair in which a downwardly directed tubular portion provided on a backrest is fitted into a metal backed support standing upright on the outside of a rear portion of a seat body, wherein the backed pillar and the downwardly directed tubular portion of the backrest are fitted. At least one or both of the downwardly directed cylindrical portions of the backrest are provided with a stress concentration suppressing means or a reinforcing means for increasing the breaking strength of a portion which intensively hits the back support when a backrest load is applied. Chair. 2. The back strut is made of a metal pipe, and as the stress concentration suppressing means, an upper end of the back strut is formed in a tapered or arcuate shape, or a cushioning protective cap is fitted to the back strut. The chair with a backrest according to claim 1, which is recessed.