CHAIR FRAME STRUCTURE AND METHOD FOR MAKING THE SAME
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.
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The present invention relates to a chair frame structure serving as the support framework of the main elements of a chair, e.g., the seat and backrest, and a method for making the same. More specifically, the present invention relates to a chair frame structure equipped with: a main seat support unit formed by joining a gas spring receiving base to which is fitted a gas spring for adjusting seat height and a seat support base for joining a seat; and a backrest frame joined to the main seat support unit for mounting of a backrest. The present invention also relates to a method for making the same.
BACKGROUND TECHNOLOGYThe main seat support unit 4 of an office chair 1 equivalent to the office chair shown in
A conventional, publicly known gas spring with a locking mechanism is used for the gas spring 3. While a detailed description of the internal structure of the locking mechanism and the like of the gas spring 3 will be omitted, pressing an operation button 3′ provided at the upper end of the rod 3b lets the rod 3b extend and retract freely relative to the main unit 3a, thus allowing the height of the seat 7 and the backrest 5 to be adjusted. Releasing the operation button 3′ restricts (locks) the extending/retracting of the rod 3b relative to the main unit 3a, thus locking the height of the seat 7 and the backrest 5 to the height selected at the time the button was released.
The main seat support unit 4 is equipped with: a seat support base 17 made of a shaped metal material formed in the shape of an upwardly opened tray; and a gas spring receiving base 18 joined to the seat support base 17. Attachment bolts 15 are adapted to attachment holes 16 formed at the four corners outside the opening of the seat support base 17. A seat shell 6 is provided below the seat 7. At the lower surface of the seat shell 6, there is formed a rectangular flat surface 26 surrounded by a frame-shaped peripheral rib 23 that projects slightly downward. Threaded holes are formed at the four corners of the flat surface 26. The attachment bolts 15 adapted to the main seat support unit 4 are screwed into the threaded holes of the seat shell 6, thereby securing the main seat support unit 4 to the seat shell 6.
A base plate section 17a is formed as a flat bottom of the seat support base 17, and at the center of the base plate section 17a is formed a through hole 19 through which the upper section of the rod 3b is inserted. A gas spring receiving base 18 is joined to the center of the seat support base 17 to form, together with the seat support base 17, a box-shaped structure. At a central position of the gas spring receiving base 18, there is formed a through hole 20 that is concentric with the through hole 19 when viewed at in the direction of the axis of the rod 3b. The gas spring receiving base 18 is formed with a flat upper surface 18a that faces the seat shell 6. The end of the rod 3b is inserted from the lower through hole 19 to the upper through hole 20, with the operation button 3′ provided at the upper end being exposed above the upper surface 18a of the gas spring receiving base 18. The seat support base 17 is joined to the upper end of the rod 3b by way of the gas spring receiving base 18. The main seat support unit 4 is raised and lowered by the extension/retraction of the rod 3b relative to the main unit 3a. The cover unit 2a that surrounds the gas spring 3 is formed with a vertically telescoping structure and is extended and retracted in tandem with the raising and lowering of the main seat support unit 4. The cover unit 2a does not, however, provide support for the load acting on the main seat support unit 4. In some chairs, the cover unit 2a may be omitted.
On the main seat support unit 4, e.g., on the side surface to the left when the chair 1 is viewed from the front, is provided a vertical groove 11 that houses an operation lever 8 in a manner that allows the lever to be moved up and down. The operation lever 8 is a member that is used to push the operation button 3′ of the gas spring 3 for adjusting the height of the chair 1. The operation lever 8 is formed from: a metal, round rod 8a with a handle 21 provided on one end and an operation unit 14 provided on the other end; and a pivot 9 secured perpendicularly to the round rod 8a. On the bottom surface of the seat shell 6, there is formed a groove 10 into which the pivot 9 can fit. A pivot support unit 25 is formed by the pivot 9 interposed between the groove 10 of the seat shell 6 and the upper section of the main seat support unit 4. The round rod 8a is formed with a curved section 22 near the operation unit 14, and the pivot 9 is welded near this curved section 22. In addition, the operation unit 14 is formed by press-forming the end of the round rod 8a from above and below to form flat upper and lower surfaces, thereby providing a larger pressing surface for applying pressure to the operation button 3′.
With regard to this type of office chair, there has been proposed a way to facilitate alignment while maintaining strength when welding the bracket to the lower surface of the seat support base (refer to Patent Document 2). In this proposed configuration, a bushing is fitted to the upper end of a gas cylinder. The bushing is passed through a seat support base and a bracket secured to the bottom surface of the seat support base, with the entire peripheral surface of the bushing forming a tight contact with a bushing through hole formed in the seat support base. The seat support base and the bracket are welded at notches formed on the bushing through hole of the bracket at intervals along the circumference. The bushing and the seat support base are welded at other positions as well, and the bracket is also welded to the seat support base at peripheral portions.
BACKGROUND TECHNOLOGY DOCUMENTS Patent Documents
- Patent Document 1: Japanese Laid-open Patent Publication Number 2008-99837
- Patent Document 2: Japanese Laid-open Patent Publication Number 2002-78555
In frame structures of chairs, there exist structural members which have to have adequate strength in designs of chairs, such as gas spring receiving bases and seat support bases as disclosed in Patent Document 1, backrests as disclosed in Patent Document 2, or other frame structures used for seats and or brackets of chairs. Conventionally, for reasons of reliability and strength, welding has been used to secure the structural members of this type of frame structure to each other or to a seat base. However, since welding involves melting and then solidifying materials, it almost always generates welding distortion and projections known as spatter at the weld portions. This is one of the causes of assembly defects and functional defects. As a result, welding distortion and spatter must be removed after welding, but this is time consuming and leads to increased costs. In addition, since predetermined positions must be welded from the inside of the main unit, the outside of the main unit must be finished with a sander. Since welding is a specialized skill, the welding operation itself can lead to increased labor costs in the production of the chairs. In addition, the operations of inexperienced welders may lead to weld cracks. As described above, a welding operation involves a large number of steps, e.g., welding, finishing, and spatter removal. As a result, the product must be moved from place to place within the workplace, with space needing to be set aside for the product and the product needing to be moved. Furthermore, the fumes from smoke generate a large amount of carbon dioxide (CO2), resulting in negative environmental impact and the like.
In some cases, the entire main seat support unit is die cast in order to reduce the weight of the chair. However, aluminum die casting requires a furnace to melt aluminum, and this involves carbon dioxide (CO2) emissions and the need to consume large amounts of power to operate the equipment. This type of single-piece die cast product has a high unit cost which makes reducing the production costs of chairs difficult. Furthermore, for technical reasons, e.g., the need to perform anaerobic welding, welding together different types of metals increases costs and generally cannot be done inexpensively. As a result, as a practical matter, welding must be done on metals of the same type.
Accordingly, with regard to frame structures for a chair obtained by joining structural members to each other in order to provide a chair framework, e.g., a main seat support unit for a chair or a backrest frame used with such a main seat support unit, providing a chair frame structure and a method for making the same that involves simple operations for joining parts, that provides reliable strength, and that does not rely on welding, which involves various problems, to join structural members is a problem to be resolved.
The object of the present invention is to provide a chair frame structure and method for making the same wherein: assembly is easy and does not depend on welding; reliable strength is provided; and production costs can be reduced.
Means for Solving the ProblemsIn order to solve the problems described above and to achieve the abovementioned object, the present invention provides 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, the main seat support unit being formed of a gas spring receiving base to which the upper end of the support column is joined and a seat support base to which the gas spring receiving base and the seat are joined, wherein the seat support base and the gas spring receiving base are joined with a blind rivet.
According to another aspect, the present invention provides 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 the support column being secured to chair legs, wherein blind rivets are used to join the main seat support unit and the backrest frame or to join structural members forming the backrest frame to each other.
According to yet another aspect, the present invention provides 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 the support column being secured to chair legs, the main seat support unit being formed of a gas spring receiving base joined to the upper end of the support column and a seat support base joined to the gas spring receiving base and the seat, wherein: the seat support base and the gas spring receiving base are joined with a blind rivet; and blind rivets are used to join the main seat support unit and the backrest frame or to join structural members forming the backrest frame to each other.
According to another aspect, the present invention provides 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 the support column being secured to chair legs, the gas spring receiving base forming the main seat support unit together with a seat support base joined to the seat, and the gas spring receiving base being joined to the upper end of the support column, wherein the gas spring receiving base is formed with a rivet insertion hole through which a blind rivet is inserted, the rivet insertion hole being formed at a position facing a rivet insertion hole provided on the seat support base and through which the blind rivet is inserted.
According to another aspect, the present invention provides 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, the main seat support unit being formed of a gas spring receiving base joined to the upper end of the support column and a seat support base joined to the gas spring receiving base and the seat, wherein: rivet insertion holes are formed previously in the gas spring receiving base and the seat support base at positions aligned with each other; when assembling the chair frame structure, the rivet insertion holes of the gas spring receiving base and the seat support base are aligned with each other and a blind rivet is inserted from outside; and the blind rivet is used to join the gas spring receiving base and the seat support base.
According to yet another aspect, the present invention provides 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 the support column being secured to chair legs, wherein: rivet insertion holes are formed previously in the main seat support unit and the backrest frame at positions aligned with each other; when assembling the chair frame structure, the rivet insertion holes in the main seat support unit and the backrest frame are aligned with each other and a blind rivet is inserted from outside; and the blind rivet is used to join the main seat support unit and the backrest frame.
In the chair frame structure and method for making the same according to the present invention, a main seat support unit is formed of: a gas spring receiving base to which is joined an upper end of a support column; and a seat support base formed by joining the gas spring receiving base and a seat. In this main seat support unit, the seat support base and the gas spring receiving base are joined using blind rivets without the use of welding. As a result, the main seat support unit can be assembled with simple riveting operations and it is possible to provide a main seat support unit with reliable strength.
In the chair frame structure and method for making the same according to the present invention, the chair frame structure is equipped with: a backrest frame that supports 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 the support column being secured to legs of the chair. Blind rivets are used to join the main seat support unit and the backrest frame or to join the structural members of the backrest frame to each other. As a result, the assembly of the backrest frame and the assembly of the main seat support unit and the backrest frame can be performed with simple riveting operations while providing reliable strength.
In this chair frame structure, various structures may be adopted to reinforce the joints formed using blind rivets. In one example, out of the seat support base, the gas spring receiving base, the main seat support unit, and the backrest frame, projected ribs or embossments are formed on one side of pairs of abutting surfaces, and holes or depressions into which the ribs or the embossments fit when joining with blind rivets are formed on surfaces of remaining side of the pairs of abutting surfaces. This reinforces the joints between the abutting surfaces.
In another example, when the gas spring receiving base is made with a synthetic resin, an upper end of a support column is fitted into a through hole formed as a truncated cone provided in the gas spring receiving base. In the through hole, a metal ring embedded using insert molding provides at least a hole surface abutting the upper end.
In yet another example, when the gas spring receiving base is made with a synthetic resin, at rivet insertion holes provided in the gas spring receiving base and through which the blind rivets are inserted, metal reinforcement members formed with holes corresponding to the rivet insertion holes and through which the blind rivets can be inserted are embedded using insert molding.
In another example, when the 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 the U-shaped cross section in order to reinforce the gas spring receiving base, and sides of the reinforcement member are joined to side walls of the gas spring receiving base using blind rivets.
According to another example, depressions capable of accommodating heads of the blind rivets or dish-shaped holes capable of accommodating the heads formed in a dish shape are provided where the blind rivets are inserted. As a result, the heads of the blind rivets are accommodated in the depressions or dish-shaped holes, preventing the heads from projecting outward. This prevents accidental snagging and collisions.
Advantages of the InventionConventionally, it has been unquestioningly assumed that the use of standard rivets may provide insufficient strength. As a result, when assembling the gas spring receiving base to which the upper end of the gas spring is joined, as well as when assembling main seat support units and backrests, joints have been formed exclusively through welding rather than with rivets. In addition, there has been no awareness that joint structures formed with rivets provide the same degree of strength as welding. In the present invention, blind rivets are used to join structural members of the main seat support unit to each other and structural members of the backrest to each other or to join the main seat support unit and the backrest, As a result, welding operations are eliminated and it is possible to provide reliable joint strength for joints between the same types of materials as well as between different types of materials, e.g., metal and synthetic resin. In addition, assembly is made easier and production costs can be reduced.
In the chair frame structure and method for making the same according to the present invention, blind rivets are used to join structural members of the main seat support unit to each other and structural members of the backrest to each other or to join the main seat support unit and the backrest. As a result, reliable and adequate joint strength can be provided even between different types of materials. Furthermore, since the joints do not rely on welding, which requires experience, it is possible to reduce the production costs of the chair. Furthermore, the number of defective products can be almost completely eliminated relative to welding.
Gas springs are used in chairs in order to adjust the height of the seat. Reliable and adequate strength and securing is provided by the use of blind rivets to join the seat support base to the gas spring receiving base to which the upper end of the gas spring is joined. Since the gas spring receiving base is not secured to the seat support base using welding, material other than iron can be used, and the gas spring can be secured firmly even if a different type of material is joined to an iron seat support base.
With the present invention, Zinkote steel plates or other materials that do not require additional coatings can be used for structural members used in the main seat support unit and other integral structural members, e.g., backrests and armrests. As a result, the need to apply coatings to these members is eliminated, resulting in an overall reduction in energy consumption and carbon dioxide emission.
In addition, with the present invention, structural members provided in association with the main seat support unit, e.g., backrests and armrests, made with die-cast materials, iron, synthetic resins, or other types of strong materials can be joined and fastened to the main seat support unit using blind rivets. Furthermore, joints that have conventionally relied on welding can be substituted with blind rivet joints. This can improve the main seat support unit while also allowing structural members provided in association with the main seat support unit to be joined with blind rivets.
Furthermore, with the present invention, welding is not used to fix the gas spring receiving base to the main seat support unit equipped with the seat support base, to fix the structural elements in the backrest to each other, or to join the main seat support unit to the backrest. As a result, various technical problems associated with welding can be avoided. For example, it is possible to reduce the emission of carbon dioxide (CO2) accompanying the combustion of welding gas. In addition, the use of members that do not require coating reduces environmental impact. In addition, it is possible to avoid problems associated with welding such as: the need to remove spatter; residual stress, distortion, and dimension errors resulting from heat or the like; the need for welding equipment/jigs; the increased costs resulting from the hiring of workers with special skills; the need to perform finishing; and the difficulty of maintaining quality levels. Furthermore, rather than requiring skilled welders to work one chair at a time, the tasks can be done by any worker who can perform standard operations. As a result, assembly can be performed using a production line, with the chair components being placed on the line to assemble the chair seat structure formed from the main seat support unit and the backrest frame structure.
Embodiments of the chair frame structure according to the present invention will be described using the attached drawings.
As shown in the perspective drawing in
As shown in
In contrast to
The gas spring receiving base 30 is equipped with a box-shaped section 31 that serves as an attachment side and a cone-shaped section 32 formed as a truncated cone that is integrally formed with the box-shaped section 31 on one side relative to the vertical axis. A vertically extending through hole 33 is formed through the box-shaped section 31 and the cone-shaped section 32. The through hole 33 is formed so that the center axis thereof is concentric with that of the cone-shaped section 32. The through hole 33 is formed in the shape fitting to the outer surface of a truncated cone, with the smallest diameter at an opening 34 in the box-shaped section 31 and the largest diameter at an opening 35 in the cone-shaped section 32. Rivet insertion holes 36 used for securing purposes are formed so as to extend vertically from top to bottom at the four corners of the box-shaped section 31 (six positions in this example).
A surface 37 is formed on the opposite side, relative to the vertical axis, of the box-shaped section 31 of the gas spring receiving base 30, i.e., the side at which the opening 34 is formed and against which the main seat support unit 4 abuts. Ribs 38, 38, 39, 39 (hereinafter referred to as “38, 39”) are formed as reinforcing projections on the surface 37. The ribs 38, 39 are two pairs of straight ribs between which the opening 34 is interposed and include the longer projected ribs 38, 38 and the shorter projected ribs 39, 39 extending perpendicular thereto. The ribs 38, 39 are provided inward from a region defined by an imaginary line connecting the openings of the rivet insertion holes 36.
Embossments 40 are formed to provide reinforcement at the four corners of the surface 37 of the box-shaped section 31 at positions outward from the region defined by an imaginary line connecting the openings of the rivet insertion holes 36. The embossments 40 are formed as short, small columns with heights similar (or identical) to the heights of the ribs 38, 39.
Although not shown in the drawings, the abutment surface of the main seat support unit 4 to which the gas spring receiving base 30 is joined is formed with depressions into which the ribs 38, 39 and the four embossments 40 fit. The engagement of the ribs 38, 39 and the embossments 40 with these depressions serves to reinforce and strengthen the attachment to the main seat support unit 4. In this example, the ribs 38, 39 and the embossments 40 are all formed on the gas spring receiving base 30, but it would also be possible to form some of these elements on the gas spring receiving base 30 with the remaining elements formed on the main seat support unit 4 or to form all of these elements on the main seat support unit 4. In these cases, the depressions into which the ribs 38, 39 and the embossments 40 fit would be formed on the opposing surfaces. Since the depressions result in reduced thickness, it would be preferable to form the depressions on whichever is thicker of the main seat support unit 4 and the gas spring receiving base 30.
The gas spring receiving base 30 is joined to the main seat support unit 4 by inserting blind rivets through the rivet insertion holes 36. Securing parts by welding is something that has been done unquestioningly out of preconception, but this has involved various problems. The use of blind rivets can eliminate these problems. While blind rivets are generally strong with regard to tension, they are weak with regard to torsion. If blind rivets alone cannot provide sufficient strength, providing the ribs 38, 39 and/or the embossments 40 can compensate for the weakness with regard to torsion of the blind rivets.
In
The gas spring receiving base 90 shown in
As shown in
The description above presents embodiments of the chair frame structure and method for making the same according to the present invention, but it is evident that various modifications and additions may be made without departing from the technical idea of the present invention. With regard to the reinforcement of the gas spring receiving base, for example, modifications and additions can be made as appropriate to the locations to reinforce, the shape and structure of the reinforcement member, and the like.
LIST OF DESIGNATORS
-
- 1: office chair
- 2: support column
- 2a: cover unit
- 3: gas spring
- 3a: main unit
- 3b: rod
- 3′: operation button
- 4: main seat support unit
- 5: backrest
- 6: seat shell
- 7: seat
- 8: operation lever
- 8a: round rod
- 9: pivot
- 10: groove
- 11: vertical groove
- 12: leg
- 14: operation unit
- 15: attachment bolt
- 16: attachment hole
- 17: seat support base
- 17a: base plate section
- 18: gas spring receiving base
- 18a: upper surface
- 19, 20: through hole
- 21: handle
- 22: curved section
- 23: frame-shaped rib
- 25: pivot support unit
- 26: flat surface
- 27a: bottom wall
- 27b: circumferential wall
- 27c: guide seat
- 28: blind rivet
- 30: gas spring receiving base
- 31: box-shaped section
- 32: truncated cone-shaped section
- 33: through hole
- 34: opening
- 35: opening
- 36: rivet insertion hole
- 37: surface
- 38, 38; 39, 39: rib
- 40: embossment
- 45: blind rivet
- 46: hole
- 47: embossment
- 48: hole
- 50: gas spring receiving base
- 51: box-shaped section
- 52: truncated cone-shaped section
- 60: first member
- 61: second member
- 62: embossment
- 63: hole
- 64: depression
- 65: large depression
- 66: small depression
- 67: dish-shaped hole
- 68, 69: blind rivet
- 70: backrest frame
- 71: tilt unit
- 72: horizontal shaft
- 73: U-shaped groove
- 73a: side wall
- 76: bent pipe
- 77: base section
- 78: blind rivet
- 79: weld
- 80: reinforcement member
- 81: top plate section
- 82: side plate section
- 83: window
- 84: small window
- 85: hole
- 86: blind rivet
- 87: polygonal pipe
- 89: round pipe
- 90: gas spring receiving base
- 91: box-shaped section
- 92: truncated cone-shaped section
- 93: through hole
- 96: rivet insertion hole
- 97: ring
- 98: rib
- 100: reinforcement member
- 101: upper/lower plate
- 102: side plate
- 103: vertical hole
- 104: horizontal hole
- 110: reinforcement member
- 111: upper/lower plate
- 112: side plate
- 113: vertical hole
- 114: horizontal hole
- 120: reinforcement plate
- 121: upper/lower plate
- 122: cylindrical section
- 123: vertical hole
- 124: inner space
- 130: reinforcement member
- 132: cylindrical section
- 134: inner space
- 140: gas spring receiving base
- 141: box-shaped section
- 142: truncated cone-shaped section
- 143: auxiliary plate
- 146: rivet insertion hole
- 150: gas spring receiving base
- 151: box-shaped section
- 152: truncated cone-shaped section
- 153: auxiliary plate
- 156: blind rivet
- 160: seat support base
- 161: bottom plate
- 170: gas spring receiving base
- 171: box-shaped section
- 172: truncated cone-shaped section
- 173: leg
- 174: auxiliary plate
- 176: rivet insertion hole
- 180: seat support base
- 180: lever
- 200: rivet
- 201: shaft
- 202: flange section
- 203: end section
- 205: shaft
- 206: head section
- 207: fragile section
- 210, 211: plate
- 212: hole
- 215: riveter
Claims
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.
Type: Application
Filed: Mar 26, 2013
Publication Date: Feb 12, 2015
Applicant: (Mitaka-shi, Tokyo)
Inventor: Fumio SUDOH
Application Number: 14/388,031
International Classification: A47C 3/30 (20060101); A47C 7/40 (20060101); A47C 5/12 (20060101); A47C 3/00 (20060101);