U.S. patent application number 14/388031 was filed with the patent office on 2015-02-12 for chair frame structure and method for making the same.
This patent application is currently assigned to Fumio SUDOH. The applicant listed for this patent is Fumio SUDOH. Invention is credited to Tadashi Namekawa, So Umehara.
Application Number | 20150042139 14/388031 |
Document ID | / |
Family ID | 49260528 |
Filed Date | 2015-02-12 |
United States Patent
Application |
20150042139 |
Kind Code |
A1 |
Namekawa; Tadashi ; et
al. |
February 12, 2015 |
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.
Inventors: |
Namekawa; Tadashi;
(Shiroi-shi, JP) ; Umehara; So; (Sagamihara-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUDOH; Fumio |
|
|
US |
|
|
Assignee: |
SUDOH; Fumio
Mitaka-shi, Tokyo
JP
|
Family ID: |
49260528 |
Appl. No.: |
14/388031 |
Filed: |
March 26, 2013 |
PCT Filed: |
March 26, 2013 |
PCT NO: |
PCT/JP2013/059799 |
371 Date: |
September 25, 2014 |
Current U.S.
Class: |
297/338 ;
29/524.1; 297/452.18 |
Current CPC
Class: |
A47C 3/00 20130101; A47C
3/30 20130101; Y10T 29/49943 20150115; A47C 7/40 20130101; A47C
7/004 20130101; A47C 7/02 20130101; A47C 5/12 20130101 |
Class at
Publication: |
297/338 ;
297/452.18; 29/524.1 |
International
Class: |
A47C 3/30 20060101
A47C003/30; A47C 7/40 20060101 A47C007/40; A47C 5/12 20060101
A47C005/12; A47C 3/00 20060101 A47C003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2012 |
JP |
2012-070469 |
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.
Description
TECHNICAL FIELD
[0001] 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 TECHNOLOGY
[0002] FIG. 14 is a perspective drawing of an example of a
conventional office chair. As shown in FIG. 14, an office chair 1
is equipped with the following main elements: a plurality of legs
12 equipped with casters at the ends thereof; a support column 2
secured to the base ends of the legs 12 and projected upward; a
main seat support unit 4 provided at the top end of the support
column 2; a seat 7 attached in a fixed manner to the main seat
support unit 4; and a backrest 5 positioned rearward from the seat
7 and elastically supported to allow rearward tilting relative to
the main seat support unit 4 (refer to Patent Document 1).
Synchronized types of chairs, in which the seat 7 can move forward
and back in tandem with the tilting of the backrest 5, have also
been proposed.
[0003] The main seat support unit 4 of an office chair 1 equivalent
to the office chair shown in FIG. 14 and the surrounding structure
thereof are shown in the perspective drawing in FIG. 15 and the
cross-section drawing in FIG. 16. As shown in FIG. 15 and FIG. 16,
the support column 2 is equipped with: a cover unit 2a that can
extend and retract along the height axis; and a gas spring 3
provided inside the cover unit 2a, the gas spring 3 allowing the
height of the chair 1, i.e., the height of the seat 7 and the
backrest 5, to be adjusted. The gas spring 3 includes: a main unit
3a with a lower end secured to the base sections of the legs 12;
and a multi-stage rod 3b that extends upward and is slidably fitted
to the main unit 3a. The main seat support unit 4 is joined to the
upper end of the rod 3b. The extending and retracting of the rod 3b
relative to the main unit 3a raises and lowers the main seat
support unit 4 integrally with the seat 7 and the backrest 5
attached thereto.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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'.
[0008] 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
[0009] Patent Document 1: Japanese Laid-open Patent Publication
Number 2008-99837 [0010] Patent Document 2: Japanese Laid-open
Patent Publication Number 2002-78555
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0011] 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
(CO.sub.2), resulting in negative environmental impact and the
like.
[0012] 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 (CO.sub.2) 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.
[0013] 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.
[0014] 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 Problems
[0015] In 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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 Invention
[0028] Conventionally, 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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 (CO.sub.2) 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 Perspective drawings showing an example of the main
elements of a chair in which a frame structure according to the
present invention is implemented.
[0035] FIG. 2 Drawings showing an example of a gas spring receiving
base used in the frame structure shown in FIG. 1.
[0036] FIG. 3 Drawings showing another example of a gas spring
receiving base used in a frame structure according to the present
invention.
[0037] FIG. 4 Drawings illustrating a frame structure according to
the present invention.
[0038] FIG. 5 Drawings showing an example of the joining structures
provided by the blind rivets used in the present invention.
[0039] FIG. 6 Drawings showing an example of reinforcement provided
for the seat support structure used in the present invention.
[0040] FIG. 7 Drawings showing other examples of joining structures
provided by the blind rivets used in the present invention.
[0041] FIG. 8 Drawings showing examples of reinforcement provided
for the gas spring receiving base used in the present
invention.
[0042] FIG. 9 A perspective drawing showing another example of a
gas spring receiving base used in the present invention.
[0043] FIG. 10 A perspective drawing showing an example of a main
seat support unit in which a gas spring receiving base used in the
present invention is assembled.
[0044] FIG. 11 A perspective drawing showing an example of a chair
frame structure according to the present invention.
[0045] FIG. 12 An exploded perspective drawing of the frame
structure shown in FIG. 11.
[0046] FIG. 13 Drawings showing examples of a blind rivet used in
the present invention.
[0047] FIG. 14 A schematic perspective drawing of a conventional
office chair upon which the present invention improves.
[0048] FIG. 15 A perspective drawing showing the seat support base
and the peripheral structure thereabout of the office chair shown
in FIG. 14.
[0049] FIG. 16 A cross-section drawing of the seat support base and
the peripheral structure thereabout of the office chair shown in
FIG. 14.
EMBODIMENTS OF THE INVENTION
[0050] Embodiments of the chair frame structure according to the
present invention will be described using the attached
drawings.
[0051] FIG. 1 shows an example of the main elements (seat support
structure) of a chair implementing the chair frame structure
according to the present invention. The perspective drawing in the
figure shows an embodiment of the chair frame structure according
to the present invention. FIG. 1 (a) is a cross-section drawing of
a seat support structure of the frame structure into which a
support column that also serves as a gas spring is inserted. FIG. 1
(b) is a cross-section drawing showing a fitting structure of a
backrest frame to the main seat support unit. FIG. 1 (c) is a
cross-section drawing showing an example of a conventional welded
joint.
[0052] As shown in the perspective drawing in FIG. 1 and the
cross-section drawing in FIG. 1 (a), a seat support base 17 of a
seat unit is formed of upper and lower half sections equipped with
bottom walls 27a, 27a and circumferential walls 27b, 27b formed
integrally by bending the peripheral portions of the bottom walls
27a, 27a. The circumferential walls 27b, 27b of the half sections
are fitted to each other and are joined by a plurality of blind
rivets 28 applied at substantially equal intervals in the
overlapping region. At the sections where the support column, which
also serves as the gas spring, is inserted, the bottom walls 27a,
27a of the half sections are provided with upwardly tapered guide
seats 27c, 27c formed by press forming.
[0053] As shown in FIG. 1, in the backrest frame 70, a box-shaped
tilt unit 71 is attached to the main seat support unit 4 by way of
a horizontal shaft 72 in a manner that allows forward-and-back
tilting. Left and right bent pipes 76, 76 are joined to the tilt
unit 71 using a plurality (two each, in the example shown in the
figure) of blind rivets 78. As shown in the cross-section detail
drawing in FIG. 1 (b), grooves 73 having U-shaped cross sections
that open upward are formed at the ends of the tilt unit 71, and
base sections 77, 77 of the bent pipes 76, 76 are fitted into the
grooves 73, 73 from above. With the base sections 77 of the bent
pipes 76 fitted into the grooves 73, blind rivets 78, 78 are
applied from the lateral outer sides of the grooves 73 into the
grooves 73 to join the bent pipes 76, 76 of the backrest frame 70
to the tilt unit 71.
[0054] In contrast to FIG. 1 (b), FIG. 1 (c) shows a cross-section
in which the bent pipes 76, 76 of the backrest frame 70 are joined
by being directly welded to the tilt unit 71. The two sides of the
tilt unit 71 are formed as side walls 73a rather than grooves.
Since the welds 79 must be formed on the curved surfaces of the
bent pipes 76, 76 to join the backrest frame 70 to the outer side
surfaces of the side walls 73a, it is evident that the welding
operation is complicated and difficult. In the present invention,
the seat support structure can be assembled using blind rivets for
all necessary attachment sites and securing sites.
[0055] FIG. 2 shows an example of a gas spring receiving base used
in the seat support structure of the chair in FIG. 1. FIG. 2 (a) is
a front-view drawing of the gas spring receiving base, FIG. 2 (b)
is a top-view drawing of the same, FIG. 2 (c) is a side-view
drawing of the same, and FIG. 2 (d) is a bottom-view drawing of the
same. A gas spring receiving base 30 is made with a material such
as synthetic resin, iron, or aluminum, and is a member that is
assembled in the seat support base 17 of the main seat support unit
4. The use of resin provides a low-cost, light-weight material that
can be processed using injection molding and the like. The resin
can be, for example, glass mixed into nylon (registered trademark).
Iron has a high specific gravity but is a low-cost material that is
easy to process. Aluminum is expensive but is light and easy to
process.
[0056] 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).
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] FIG. 3 shows another example of a gas spring receiving base
used in the seat support structure shown in FIG. 1. FIG. 3 (a) is a
front-view drawing of the gas spring receiving base. FIG. 3 (b) is
a top-view drawing of the same. FIG. 3 (c) is a side-view drawing
of the same. FIG. 3 (d) is a bottom-view drawing of the same. In
FIG. 3, a gas spring receiving base 50 is a member that is
assembled in the main seat support unit 4 and is equipped with a
box-shaped section 51 that serves as an attachment side and a
truncated frustum-shaped section 52 that is integrally formed with
the box-shaped section 51 on one side relative to the vertical
axis. The width of the truncated frustum-shaped section 52 is the
same as the width of the box-shaped section 51 and, as shown in the
front-view drawing, the truncated frustum-shaped section 52 is
tapered laterally. The outer shape of the truncated frustum-shaped
section 52 is defined to match the shape/structure of the main seat
support unit 4. Since the structure used to assemble the gas spring
receiving base in the main seat support unit 4 using blind rivets
is the same as in the previous example, other shapes/structures are
assigned the same numerals as those used in the gas spring
receiving base 30 shown in FIG. 2 and redundant descriptions of
these will be omitted.
[0062] FIG. 4 shows the structure by which the gas spring receiving
base shown in FIG. 2 is joined to the chair seat support structure
shown in FIG. 1 using blind rivets. In FIG. 4, the circled inset X
at the center shows the manner how the gas spring receiving base 30
is joined using blind rivets 45 inserted through holes 46 formed on
the seat support base 17. The rectangular inset Y toward the right
of the figure shows the gas spring receiving base 30, from FIG. 2.
The circled inset Z toward the bottom center of FIG. 4 shows the
manner how, at the structure wherein the base sections 77, 77 of
the bent pipes 76, 76 of the backrest frame 70 are fitted from
above into the grooves 73, 73 formed on either side of the tilt
unit 71, an embossments 47 formed on one side is fitted into a hole
48 formed on the other side. The operation of the gas spring using
the lever is as described in the background technology.
[0063] FIG. 5 illustrates how the two members (the main seat
support unit 4 and the gas spring receiving base 30) formed with
embossments and holes into which they fit are assembled. In FIG. 5
(a), an embossments 62 formed on a first member 60 is fitted in a
hole 63 formed on a second member 61 and the members 60, 61 are
joined using blind rivets 68, 68 inserted/applied in holes formed
on the members 60, 61 to the left and the right of the embossments
62 and the hole 63. By using the member 61 as the member facing the
outside of the device (the unobstructed side) and the member 60 as
the member facing inside the device, it is possible to apply the
blind rivets 68, 68 from the outside.
[0064] In FIG. 5 (b), the embossments 62 formed on the first member
60 is fitted in an depressions 64 formed on the second member 61,
and the members 60, 61 are joined by the blind rivet 68 applied
nearby. In FIG. 5 (c), the embossing 62 formed on the first member
60 is fitted in the hole 63 formed on the second member 61, and the
members 60, 61 are joined by the blind rivet 68 applied nearby. In
FIG. 5 (d), a small depressions 66 formed on the second member 61
is fitted in a large depressions 65 formed on the first member 60,
and a blind rivet 68 is applied in these depressions to join the
members. This prevents the head of the blind rivet 68 from being
projected out from the second member 61. In FIG. 5 (e), the members
are joined using a blind rivet 69 formed with a dish-shaped head
that is inserted through and applied in a hole formed in the first
member 60 and a dish-shaped hole 67 formed in the second member 61
to align with the hole. This also prevents the head of the blind
rivet 69 from being projected out from the second member 61.
Details regarding the insertion/application of the blind rivet 68
in FIG. 5 (b) to (e) are the same as in FIG. 5 (a).
[0065] FIG. 6 shows an example of a seat support structure in a
chair according to the present invention. FIG. 6 (a) is a
cross-section drawing showing a seat support structure with a
reinforced main seat support unit 4. FIG. 6 (b) is a perspective
drawing of an example of a reinforcement member of the same. As
shown in FIG. 1 and FIG. 4, the main seat support unit 4 of the
seat support structure is formed as a thin plate having a U-shaped
cross section opening upward. A reinforcement member 80 is formed
with a width that allows it to fit snugly into the main seat
support unit 4 and is equipped with a top plate section 81 with a
window 83 formed at the center thereof to reduce weight and side
plate sections 82 formed integrally with the top plate section 81
by bending on either side of the top plate section 81. In order to
provide a light-weight design, small windows 84 are formed on the
side plate sections 82 as well, and holes 85 for applying blind
rivets are formed in alignment with the small windows 84. Blind
rivets 86 are inserted from the outside of the main seat support
unit 4 into the holes formed on the main seat support unit 4 and
the holes 85 of the reinforcement member 81 aligned (facing) the
holes in the main seat support unit 4, and riveting is performed
from the outside of the main seat support unit 4. This provides a
reinforced seat support structure in which the reinforcement member
81 is assembled to the main seat support unit 4. With the
reinforcement member 81, the main seat support unit 4 is formed as
a structure with a closed cross section, thus allowing the rigidity
of the main seat support unit 4 to be improved without the use of
welding.
[0066] FIG. 7 shows cross-section drawings of alternative examples
of the reinforcement structure for the seat support structure of
the chair according to the present invention. In addition to pipes
with round cross sections, pipes with polygonal cross sections may
be assembled to the main seat support unit 4 of the seat support
structure, e.g., when assembling a rod to support the backrest.
FIG. 7 (a) shows an example in which a polygonal pipe 87 is
assembled to a flat section 4a of the main seat support unit 4
inside the main seat support unit 4. A hole formed in the main seat
support unit 4 is aligned with (faces) a hole formed on a side of
the polygonal pipe 87, the blind rivet 86 is inserted through the
aligned holes from the outside of the main seat support unit 4, and
riveting is performed from the outside of the main seat support
unit 4. As a result, the polygonal pipe 87 can be assembled with a
simple operation to the main seat support unit 4 without the need
for welding.
[0067] FIG. 7 (b) and FIG. 7 (c) show examples of assembling a pipe
89 with a round cross section to the inside of the main seat
support unit 4. In FIG. 7 (b), the main seat support unit 4 is
formed with a shape that includes a curved section 4b that supports
no more than half cylindrical surface with the cross-section of the
round pipe 89. A single hole formed in the curved section 4b and a
single hole formed in the round pipe 89 are aligned, the blind
rivet 86 is inserted through the aligned holes from the outside of
the main seat support unit 4, and riveting is performed from the
outside of the main seat support unit 4. In FIG. 7 (c), the main
seat support unit 4 is formed with a shape that includes a curved
section 4c that supports more than half cylindrical surface with
the cross-section of the round pipe 89. Three holes formed at equal
intervals along the circumferential direction of the curved section
4c are aligned with three holes formed similarly on the round pipe
89, the blind rivets 86 are inserted through the three aligned
holes from the outside of the main seat support unit 4, and
riveting is performed from the outside of the main seat support
unit 4. As a result, in FIG. 7 (b) and FIG. 7 (c), the round pipe
89 can be assembled with a simple operation without the need for
welding.
[0068] FIG. 8 shows another example of a gas spring receiving base
used in the seat support structure of the chair shown in FIG. 1.
FIG. 8 (a) is a top-view drawing of the gas spring receiving base.
FIG. 8 (b) is a front-view drawing of the same. FIG. 8 (c) is a
drawing of an inserted ring. FIG. 8 [A] to [D] show examples of
inserted reinforcement members. The use of resin for a gas spring
receiving base 90 assembled in the main seat support unit 4
provides a low-cost, light-weight material that can be processed
using injection molding and the like. If there are positions that
need to be strong, the inclusion of a metal member, e.g., iron, in
the resin at these positions using insert molding can provide
greater strength.
[0069] The gas spring receiving base 90 shown in FIG. 8 (a) and
FIG. 8 (b) is, essentially, joined to the seat support base 17 and
has a structure similar to those of the gas spring receiving bases
30, 50 shown in FIG. 2 and FIG. 3. More specifically, the gas
spring receiving base 90 is equipped with a box-shaped section 91
and a truncated cone-shaped section 92 as well as a through hole 93
formed as a truncated cone into which a support column is fitted.
Rivet insertion holes 96 are formed at the four corners of the gas
spring receiving base 90 for the blind rivets to be inserted so as
to join to the seat base 17. An iron ring 97 is provided at the
upper section of the through hole 93, against which the support
column abuts when it is inserted, by insert molding performed when
forming the gas spring receiving base 90. The inner surface of the
ring 97 is exposed and is continuous with the inner peripheral
surface of the truncated cone shape of the through hole 93. If
further strength is needed, the ring 97 can, for example, be
provided with ribs 98 formed on the outer peripheral surface
thereof to provide reinforcement. The ribs 98 increase the strength
of the ring 97 itself, while also improving the bond between the
resin and the ring embedded in the resin through insert
molding.
[0070] FIG. 8 [A] to FIG. 8 [D] show other examples of inserted
reinforcement members. Reinforcement members 100 shown in FIG. 8
[B] are inserted into the gas spring receiving base 90 shown in
FIG. 8 (a) and FIG. 8 (b). The reinforcement member 100 shown in
FIG. 8 [B] has a U-shaped cross-section. When the reinforcement
members 100 are inserted, upper/lower plates 101, 101 are exposed
at the surface of the box-shaped section 91 and side plates 102 are
embedded in resin. Vertical holes 103, 103 are formed in the
upper/lower plates 101, 101, and a horizontal hole 104 is formed in
the side plate 102. The vertical holes 103, 103 are aligned with
the rivet insertion holes 96. Blind rivets can be inserted through
the rivet insertion holes 96 and the vertical holes 103, 103 and
riveted.
[0071] FIG. 8 [A] shows a reinforcement member 110 formed with a
cross section shaped as a four-sided ring. When the reinforcement
member 110 is inserted, upper/lower plates 111, 111 are exposed at
the surfaces of the box-shaped section 91 and side plates 112, 112
are embedded in resin. Vertical holes 113, 113 formed in the
upper/lower plates 111, 111 are aligned with the rivet insertion
holes 96. The insert positions and the relationship with the blind
rivets are the same as in the reinforcement member 100 shown in
FIG. 8 [B] so a detailed description will be omitted. In FIG. 8
[C], a reinforcement plate 120 includes upper/lower plates 121, 121
and a cylindrical section 122 connecting these plates 121, 121.
When inserted, the upper/lower plates 121, 121 are exposed at the
surfaces of the box-shaped section 91 and the cylindrical section
122 is embedded in the resin. The upper/lower plates 121, 121 are
formed with vertical holes 123, 123 that are in alignment with each
other. An inner space 124 of the cylindrical section 122 serves as
the rivet insertion hole 96. In FIG. 8 [D], a reinforcement member
130 is formed only from a cylindrical section 132, with no upper or
lower plate. The upper and lower ends of the cylindrical section
132 are exposed at the surfaces of the box-shaped section 91 while
the peripheral surface is embedded in resin. The inner space 134 of
the cylindrical section 132 can be used as the rivet insertion hole
96. If the reinforcement members 100 to 130 need further
reinforcement, ribs can be formed, preferably at appropriate
positions of the reinforcement members that come into contact with
the resin, as in the ring 97.
[0072] FIGS. 9 to 12 are perspective drawings showing another
embodiment of a main seat support unit and a gas spring receiving
base to be assembled therein according to the present invention.
FIG. 9 shows a gas spring receiving base 140 that is equipped with
a box-shaped section 141 and a truncated cone-shaped section 142.
Furthermore, taking the connection with the seat support base into
account, auxiliary plates 143, 143 are provided integrally on the
box-shaped section 141. Rivet insertion holes 146 aligned with the
rivet insertion holes on the main seat support unit are formed on
the auxiliary plates 143, 143. Blind rivets can also be used on the
auxiliary plates 143, 143 to assemble the gas spring receiving base
to the main seat support unit.
[0073] FIG. 10 is a perspective drawing of an example of a main
seat support unit formed of a gas spring receiving base 150 and a
seat support base 160 to which a gas spring receiving base 150 is
joined. The gas spring receiving base 150 is joined to a bottom
plate 161 of the seat support base 160 from the bottom. A
box-shaped section 151 of the gas spring receiving base 150 is
abutted against the bottom plate 161, and a truncated cone-shaped
section 152 is inserted through the bottom plate 161 and projects
into the seat support base 160. Auxiliary plates 153, 153 are
provided integrally on either side of the gas spring receiving base
150 and are formed parallel to the bottom plate 161. Each auxiliary
plate 153 is formed with a plurality of rivet insertion holes for
securing the gas spring receiving base 150 to the bottom plate 161.
The gas spring receiving base 150 is joined to the seat support
base 160 using blind rivets 156 inserted from the outside of the
seat support base 160 through the rivet insertion holes in the
auxiliary plates 153, 153.
[0074] FIG. 11 and FIG. 12 show perspective drawings of an example
of a main seat support unit formed of a gas spring receiving base
170 and a seat support base 180 to which a gas spring receiving
base 170 is joined. FIG. 11 shows the gas spring receiving base 170
joined to the seat support base 180, while FIG. 12 shows the
non-assembled state before joining. The seat support base 180 is
formed as a long, thin box, with the gas spring receiving base 170
provided toward one end. Since the upper end of the gas spring is
fitted into the gas spring receiving base 170, a lever 181 of the
seat support base 180 that operates the gas spring is provided in
association with the gas spring receiving base 170. The structure
of the gas spring receiving base 170 is essentially similar to the
structure of the gas spring receiving base 140 shown in FIG. 9. In
order to accommodate the greater height of the seat support base
180, a box-shaped section 171 of the gas spring receiving base 170
is provided with legs 173, 173 opposite from a truncated
cone-shaped section 172. One of the legs 173 is provided with an
auxiliary plate 174 extending parallel to the box-shaped section
171. The auxiliary plate 174 is formed with rivet insertion holes
176 so that it can be secured to the seat support base 180 using
blind rivets.
[0075] FIG. 13 shows an example of a blind rivet used in the
present invention and usage examples of the same. FIG. 13 (a) is a
longitudinal cross-section drawing showing an example of a blind
rivet used in the present invention. FIG. 13 (b) to (e) illustrate
sequentially how a blind rivet is used to join two plates. As shown
in FIG. 13 (a), the blind rivet 68 (28, 45, 68, 69, 78, 86, 156) is
a rivet with a structure that allows it to be crimped from the side
from which the rivet is inserted. When a shaft 205 inserted through
a hollow rivet 200 is pulled back, the rivet 200 is deformed and
crimped. Then, the shaft 205 breaks midway, leaving behind the
crimped rivet 200. The rivet 200 is equipped with a shaft section
201 and a flange section 202 toward the front. The shaft 205 is
provided at the end thereof with a head section 206, the diameter
thereof being larger than the diameter of the opening of the shaft
section 201 of the rivet 200 and smaller than the outer diameter of
the shaft section 201.
[0076] As shown in FIG. 13 (b), the two plates 210, 211 to be
joined are formed with a hole 212 through which the rivet 200
before crimping can be inserted. The blind rivet 68, in which the
rivet 200 is attached to the shaft 205, is inserted from the front
side (the side of the plate 211) of the plates through the hole
212, with the rivet 200 extending behind the plate 210 (FIG. 13
(c)). Using a riveter 215, the shaft 205 is pulled toward the front
while the flange section 202 of the rivet 200 is pushed toward the
plates 210, 211. As a result, the head section 206 of the shaft 205
crimps the end of the shaft section 201 of the rivet 200, causing
it to expand sideways. The plates 210, 211 are joined to each other
by being clamped between the flange section 202 of the rivet 201
and the end section 203 of the rivet 200 that has been crimped so
as to expand laterally (FIG. 13 (d) to (e)). The breaking of the
shaft 205 at a fragile section 207 (refer to FIG. 13 (a))
positioned inside the rivet 200 allows the front side section of
the shaft 205 to be removed and retrieved from the rivet 200. As a
result, crimping does not need to be performed from both sides as
in standard solid rivets, thus significantly improving ease of
assembly, and it has been observed that adequate strength is
provided.
[0077] 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
[0078] 1: office chair [0079] 2: support column [0080] 2a: cover
unit [0081] 3: gas spring [0082] 3a: main unit [0083] 3b: rod
[0084] 3': operation button [0085] 4: main seat support unit [0086]
5: backrest [0087] 6: seat shell [0088] 7: seat [0089] 8: operation
lever [0090] 8a: round rod [0091] 9: pivot [0092] 10: groove [0093]
11: vertical groove [0094] 12: leg [0095] 14: operation unit [0096]
15: attachment bolt [0097] 16: attachment hole [0098] 17: seat
support base [0099] 17a: base plate section [0100] 18: gas spring
receiving base [0101] 18a: upper surface [0102] 19, 20: through
hole [0103] 21: handle [0104] 22: curved section [0105] 23:
frame-shaped rib [0106] 25: pivot support unit [0107] 26: flat
surface [0108] 27a: bottom wall [0109] 27b: circumferential wall
[0110] 27c: guide seat [0111] 28: blind rivet [0112] 30: gas spring
receiving base [0113] 31: box-shaped section [0114] 32: truncated
cone-shaped section [0115] 33: through hole [0116] 34: opening
[0117] 35: opening [0118] 36: rivet insertion hole [0119] 37:
surface [0120] 38, 38; 39, 39: rib [0121] 40: embossment [0122] 45:
blind rivet [0123] 46: hole [0124] 47: embossment [0125] 48: hole
[0126] 50: gas spring receiving base [0127] 51: box-shaped section
[0128] 52: truncated cone-shaped section [0129] 60: first member
[0130] 61: second member [0131] 62: embossment [0132] 63: hole
[0133] 64: depression [0134] 65: large depression [0135] 66: small
depression [0136] 67: dish-shaped hole [0137] 68, 69: blind rivet
[0138] 70: backrest frame [0139] 71: tilt unit [0140] 72:
horizontal shaft [0141] 73: U-shaped groove [0142] 73a: side wall
[0143] 76: bent pipe [0144] 77: base section [0145] 78: blind rivet
[0146] 79: weld [0147] 80: reinforcement member [0148] 81: top
plate section [0149] 82: side plate section [0150] 83: window
[0151] 84: small window [0152] 85: hole [0153] 86: blind rivet
[0154] 87: polygonal pipe [0155] 89: round pipe [0156] 90: gas
spring receiving base [0157] 91: box-shaped section [0158] 92:
truncated cone-shaped section [0159] 93: through hole [0160] 96:
rivet insertion hole [0161] 97: ring [0162] 98: rib [0163] 100:
reinforcement member [0164] 101: upper/lower plate [0165] 102: side
plate [0166] 103: vertical hole [0167] 104: horizontal hole [0168]
110: reinforcement member [0169] 111: upper/lower plate [0170] 112:
side plate [0171] 113: vertical hole [0172] 114: horizontal hole
[0173] 120: reinforcement plate [0174] 121: upper/lower plate
[0175] 122: cylindrical section [0176] 123: vertical hole [0177]
124: inner space [0178] 130: reinforcement member [0179] 132:
cylindrical section [0180] 134: inner space [0181] 140: gas spring
receiving base [0182] 141: box-shaped section [0183] 142: truncated
cone-shaped section [0184] 143: auxiliary plate [0185] 146: rivet
insertion hole [0186] 150: gas spring receiving base [0187] 151:
box-shaped section [0188] 152: truncated cone-shaped section [0189]
153: auxiliary plate [0190] 156: blind rivet [0191] 160: seat
support base [0192] 161: bottom plate [0193] 170: gas spring
receiving base [0194] 171: box-shaped section [0195] 172: truncated
cone-shaped section [0196] 173: leg [0197] 174: auxiliary plate
[0198] 176: rivet insertion hole [0199] 180: seat support base
[0200] 180: lever [0201] 200: rivet [0202] 201: shaft [0203] 202:
flange section [0204] 203: end section [0205] 205: shaft [0206]
206: head section [0207] 207: fragile section [0208] 210, 211:
plate [0209] 212: hole [0210] 215: riveter
* * * * *