JP2003325264A - Chair leg having inclined arch shape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide chair legs which are excellent in strength and rigidity against a vertical load. <P>SOLUTION: The horizontal projection length of each leg is defined as L, the vertical projection height is defined as H, and a ratio of L/H is 1.5 to 10. Not less than 1/4 of the leg is formed in an arch shape curve. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the form of legs of an office chair. More specifically, the present invention relates to a leg shape having excellent strength and rigidity with respect to a vertical load.

[0002]

2. Description of the Related Art The legs of an office chair are usually a cylindrical base that supports a support rod (usually a gas spring) that supports a seat, and several beams that are evenly distributed horizontally from the cylindrical base. It consists of legs (usually 5). When the chair seat is loaded, a vertical load is applied to the cylindrical base through the support rods, and the load is supported by the beam-shaped legs. Therefore, a bending moment is applied to the leg having the cylindrical base portion as the fixed end. Usually, the base leg (fixed end) of the cylindrical base is subjected to the maximum bending stress, and therefore the base leg of the cylindrical base must have a shape having a sufficient section modulus to withstand a predetermined load. In recent years, resin legs are often used from the viewpoints of productivity, cost, design freedom and the like.

However, when resin is used as the material for the legs, the resin is inferior in strength and rigidity to metals such as aluminum and steel. Although a functional design is made with a rib structure or the like so that the value of the second moment becomes large, it is unavoidable that the dimension is larger than that of metal even in the present situation. Under the above-mentioned circumstances, design has been emphasized in recent years, and there is also a side in which thin and beautiful leg shapes are desired. However, at present, there has not been proposed a functional design that is thin and has satisfactory strength and rigidity with respect to the shape of the legs.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a leg shape which is excellent in strength and rigidity, particularly for a leg made of resin.

[0005]

Means for Solving the Problems As a result of intensive studies on the shape and shape of the leg, the present inventors have found that the specific shape and shape are excellent in strength and rigidity against a load, and have arrived at the present invention. That is, the chair of the present invention is a chair having at least three beam-shaped legs, and the projected length L of the legs in the horizontal direction is L.
And a ratio L / H of the projection height H in the vertical direction is in the range of 1.5 to 10, and at least 1/4 or more of the legs are formed by arched curves. .

The present invention will be described in detail below. FIG. 1 shows a schematic sectional view of the chair of the present invention. Although the cross-sectional shape of the leg is simply a solid circular simple shape, the present invention is not limited to the cross-sectional shape of the leg. In the figure, a indicates a support rod leg that supports the seat, and c indicates a cylindrical base portion that supports the support rod. b indicates a leg, and the larger the ratio L / H of the projected length L of the leg in the horizontal direction to the projected height H of the leg in the vertical direction is, the larger the shape of the leg is against the load, but the seat height is higher. From the viewpoint of the mechanism such as height and height adjustment allowance, L / H is preferably 1.5 to 10, and more preferably 3 to 7.

The leg b is integrated with the cylindrical base portion a and is formed in an arched curve in the longitudinal direction. The smaller the curvature of the leg arch, the stronger the load. Most preferably, the entire leg is formed of arched curves,
At least 1/4 or more of the legs are preferably formed by arch-shaped curves. The reason why the arched leg is preferable is that the arched leg has the same L / H (ratio of the projected length L of the leg in the horizontal direction to the projected height H of the leg in the vertical direction) as compared with the leg on a straight line. Is because the absolute value of the length of the leg becomes long, so that it becomes strong against the load.

For the legs of the chair of the present invention, a metal material itself such as aluminum or steel can be used. On the other hand, for the purpose of weight reduction or design aesthetics, a resin material can be used, and the whole or a part of the metal core is processed by injection molding or extrusion molding,
What was covered with the resin material can be used. The resin material of the present invention is a thermoplastic resin or a resin composition comprising the thermoplastic resin.

The thermoplastic resin of the present invention is a polyamide, polyester, polycarbonate or styrene resin, and specifically includes the following. The polyamide of the present invention is not particularly limited as long as it is a known polyamide. For example, polycaprolactam, polytetramethylene adipamide, polyhexamethylene adipamide, polyhexamethylene sebacamide, polyhexamethylene dodecamide, polyundecamethylene adipamide, polyundecalactam, polydodecaractam, poly Trimethylhexamethylene terephthalamide, polyhexamethylene isophthalamide, polynonane methylene terephthalamide, polyhexamethylene terephthalamide and polyamide copolymers containing at least two or more different polyamide forming components, and mixtures thereof. .

Preferably, polycaprolactam, polyhexamethylene adipamide, polyhexamethylene dodecamide, and polyhexamethylene isophthalamide, and polyamide copolymers containing two or more different polyamide forming components and their A mixture etc. can be mentioned. The polyester of the present invention is a thermoplastic polyester comprising a divalent or higher carboxylic acid or an ester-forming derivative thereof and a divalent or higher hydroxyl-containing compound or an ester-forming derivative thereof. Examples of the divalent or higher carboxylic acid or its ester-forming derivative include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, bis (p-carboxyphenyl) methaneanthracene dicarboxylic acid, adipic acid and derivatives having ester forming ability thereof. Can be mentioned.

Examples of the hydroxyl group-containing compound include ethylene glycol, 1,3-propanediol, butanediol, hexanediol, trimethylenediol, cyclohexanedimethanol and the like. Examples of preferable polyesters include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate and the like.

The polycarbonate of the present invention is obtained by melt polycondensing an aromatic dihydroxy compound and a carbonic acid diester in the presence of a catalyst to obtain a polycarbonate. Such aromatic dihydroxy compounds include, for example, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis. (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxy-1-methylphenyl) propane, 1,1 -Bis (4-hydroxy-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane and other bis (hydroxyaryl) alkanes, 1,1-bis (4-hydroxyphenyl) ) Bis (hydroxyaryl) cycloalkanes such as cyclopentane. These aromatic dihydroxy compounds can be used alone or in combination.

The carbonic acid diesters include, for example, diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, diethyl carbonate,
It is dimethyl carbonate and dicyclohexyl diethyl carbonate. These carbonic acid diesters can be used alone or in combination. The styrene resin of the present invention is a graft polymer obtained by graft-polymerizing a monomer containing an aromatic vinyl monomer and an unsaturated nitrile monomer to a rubber-like polymer, or the graft polymer and an aromatic compound. It is a mixture with a vinyl copolymer obtained by polymerizing a monomer containing a group vinyl monomer and an unsaturated nitrile monomer. It is usually a resin material called ABS resin.

The resin composition of the present invention is a mixture of the above-mentioned thermoplastic resin with at least one kind of glass fiber, carbon fiber and metal fiber, and usually 100 parts by weight of the thermoplastic resin. 5 to 70 parts by weight, preferably 10
-60 parts by weight, more preferably 25-50 parts by weight. Further, as the resin of the preferred embodiment of the present invention,
For example, glass reinforced polyamide, glass reinforced polybutylene terephthalate, glass reinforced polyethylene terephthalate, glass reinforced polycarbonate, glass reinforced styrene resin, etc. are preferably used.

Needless to say, the heat stabilizer, weatherproofing agent, processing aid and the like which are usually used are used in the resin material of the present invention, but it is one of the purposes of the present invention to reduce the weight or When design aesthetics are emphasized, for example, inorganic pigments such as titanium oxide, rouge, carbon black, and the like, and dyes such as anthraquinone, monoazo, and heterocyclic compounds can be used in combination.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, examples and comparative examples will be described with reference to the drawings, but the cross-sectional shapes of the legs are not limited thereto.

[0017]

[Examples and Comparative Examples 1-2] With respect to five legs having a circular cross section with a diameter of 30 mm, the maximum deflection and the maximum stress generated when a load of 7500 N was applied by changing the form of the legs were CA.
E simulation was performed and compared. The results are shown in Table 1. For CAE stress analysis, I-DEAS software was used and the Von Mises method was adopted. Leona 54G33 (trademark, manufactured by Asahi Kasei Corp., glass fiber reinforced polyamide 66 resin (glass fiber content 33% by weight)) was used as the analyzed material. Specific gravity 1.39, flexural modulus 5000M
Enter Pa and Poisson's ratio of 0.35 as physical property data of Leona 54G33 (containing 33% by weight of glass fiber), and
E stress analysis was performed.

As can be seen from Table 1, the maximum stress generated in the inclined curved leg of the present invention is about half or less as compared with the flat linear leg of Comparative Example 1, and the inclined linear leg of Comparative Example 2 is less than half. It was about 3/4 compared with. The amount of deflection was about half that of the flat linear leg of Comparative Example 1, and was almost the same as that of the inclined linear leg of Comparative Example 2.

[0019]

[Table 1]

[0020]

INDUSTRIAL APPLICABILITY The present invention provides a chair leg shape excellent in strength and flexure against a load, and is particularly useful for a resin having a lower strength than metal.

[Brief description of drawings]

FIG. 1 is a schematic view of legs of a chair of the present invention.

[Explanation of symbols]

a Support rod that supports the seat b leg c Cylindrical base that supports the support rod Vertical projection height of H leg Horizontal projection length of L leg

Claims (7)

[Claims] 1. A chair having at least three beam-shaped legs, wherein the ratio L / H of the projected length L of the legs in the horizontal direction to the projected height H of the legs is 1.5 to 10. The chair is characterized in that it is in the range of, and more than ¼ of the legs are formed by arched curves. 2. The chair according to claim 1, wherein the legs are made of metal and / or resin material. 3. The chair according to claim 2, wherein the resin material comprises a thermoplastic resin or the resin composition. 4. The chair according to claim 3, wherein the resin material is a thermoplastic polyamide-based resin or the resin composition. 5. The chair according to claim 3, wherein the resin material is a thermoplastic polyester resin or the resin composition. 6. The chair according to claim 3, wherein the resin material is a polycarbonate thermoplastic resin or the resin composition. 7. The resin material is a styrenic thermoplastic resin or the resin composition.
The chair described in.