Chair frame structure and method for making the same

Abstract

A chair frame structure and method for making the same that allows efficient assembly without dependence on welding, provides reliable strength, and allows production costs to be reduced. The chair frame structure includes a gas spring receiving base into which an end of a gas spring is inserted and abutted is joined to a seat support base of a main seat support unit. The gas spring receiving base is joined to the seat support base using blind rivets applied at a plurality of positions by the operation performed from outside. Since the gas spring receiving base is joined using blind rivets without reliance on welding, it is possible to achieve an efficient, low-cost seat structure that provides adequate strength with a simple structure.

1 . A chair frame structure that is equipped with a main seat support unit to which are joined a seat and an upper end of a support column having a lower end thereof secured to chair legs, said main seat support unit being formed of a gas spring receiving base to which said upper end of said support column is joined and a seat support base to which said gas spring receiving base and said seat are joined,
 wherein said seat support base and said gas spring receiving base are joined with a blind rivet.   
     
     
         2 . A chair frame structure equipped with a backrest frame supporting a backrest and a main seat support unit to which are joined a seat and an upper end of a support column, a lower end of said support column being secured to chair legs,
 wherein blind rivets are used to join said main seat support unit and said backrest frame or to join structural members forming said backrest frame to each other.   
     
     
         3 . A chair frame structure equipped with a backrest frame supporting a backrest and a main seat support unit to which are joined a seat and an upper end of a support column, a lower end of said support column being secured to chair legs, said main seat support unit being formed of a gas spring receiving base joined to said upper end of said support column and a seat support base joined to said gas spring receiving base and said seat,
 wherein:   said seat support base and said gas spring receiving base are joined with a blind rivet;   and blind rivets are used to join said main seat support unit and said backrest frame or to join structural members forming said backrest frame to each other   
     
     
         4 . A chair frame structure according to  claim 1  wherein, in order to reinforce joints formed with said blind rivets: out of said seat support base, said gas spring receiving base, said main seat support unit, and said backrest frame, projected ribs or embossments are formed on one side of pairs of abutting surfaces; and
 holes or depressions into which said ribs or said embossments fit when joining with blind rivets are formed on surfaces of remaining sides of said pairs of abutting surfaces. 
 
     
     
         5 . A chair frame structure according to  claim 4  wherein, in order to prevent heads of said blind rivets from being projected, depressions capable of accommodating said heads or dish-shaped holes capable of accommodating said heads formed in a dish shape are provided where said blind rivets are inserted. 
     
     
         6 . A chair frame structure according to  claim 1  wherein:
 said gas spring receiving base is made with a synthetic resin; and, 
 in a through hole formed as a truncated cone provided in said gas spring receiving base into which said upper end of said support column is fitted, a metal ring embedded using insert molding forms at least a hole surface abutting said upper end. 
 
     
     
         7 . A chair frame structure according to  claim 1  wherein:
 said gas spring receiving base is made with a synthetic resin; and 
 at rivet insertion holes provided in said gas spring receiving base and through which said blind rivets are inserted, metal reinforcement members formed with holes corresponding to said rivet insertion holes and through which said blind rivets can be inserted are embedded using insert molding. 
 
     
     
         8 . A chair frame structure according to  claim 1  wherein:
 said gas spring receiving base is formed with a U-shaped cross section that opens upward; 
 a plate-shaped reinforcement member covers an open top side of said U-shaped cross section in order to reinforce said gas spring receiving base; and 
 sides of said reinforcement member are joined to side walls of said gas spring receiving base using blind rivets. 
 
     
     
         9 . A gas spring receiving base in a chair frame structure equipped with a main seat support unit to which are joined a seat and an upper end of a support column, a lower end of said support column being secured to chair legs, said gas spring receiving base forming said main seat support unit together with a seat support base joined to said seat, and said gas spring receiving base being joined to said upper end of said support column,
 wherein said gas spring receiving base is formed with a rivet insertion hole through which a blind rivet is inserted, said rivet insertion hole being formed at a position facing a rivet insertion hole provided on said seat support base and through which said blind rivet is inserted.   
     
     
         10 . A gas spring receiving base in a chair frame structure according to  claim 9  wherein:
 said gas spring receiving base is made with a synthetic resin; and 
 said gas spring receiving base into which said upper end of said support column is fitted is provided with a through hole formed as a truncated cone, a metal ring being embedded using insert molding in said through hole to form at least a hole surface abutting said upper end. 
 
     
     
         11 . A gas spring receiving base in a chair frame structure according to  claim 9  wherein:
 said gas spring receiving base is made with a synthetic resin; and, 
 at rivet insertion holes provided in said gas spring receiving base and through which said blind rivets are inserted, metal reinforcement members formed with holes corresponding to said rivet insertion holes and through which said blind rivets can be inserted are embedded using insert molding. 
 
     
     
         12 . A method for making a chair frame structure that is equipped with a main seat support unit to which are joined a seat and an upper end of a support column having a lower end thereof secured to chair legs, said main seat support unit being formed of a gas spring receiving base joined to said upper end of said support column and a seat support base joined to said gas spring receiving base and said seat,
 wherein:   rivet insertion holes are formed previously in said gas spring receiving base and said seat support base at positions aligned with each other;   when assembling said chair frame structure, said rivet insertion holes of said gas spring receiving base and said seat support base are aligned with each other and a blind rivet is inserted from outside; and   said blind rivet is used to join said gas spring receiving base and said seat support base.   
     
     
         13 . A method for making a chair frame structure equipped with a backrest frame supporting a backrest and a main seat support unit to which are joined a seat and an upper end of a support column, a lower end of said support column being secured to chair legs,
 wherein:   rivet insertion holes are formed previously in said main seat support unit and said backrest frame at positions aligned with each other;   when assembling said chair frame structure, said rivet insertion holes in said main seat support unit and said backrest frame are aligned with each other and a blind rivet is inserted from outside; and   said blind rivet is used to join said main seat support unit and said backrest frame.