JPH0523095Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a chair with a backrest in which the backrest is supported by a back support rod.

[Prior Art] As this type of chair with a backrest, a seat is disposed on a support base supported at the upper end of a pillar, and
It is known that a back support rod is pivotally supported on the support base so as to be tiltable in the front and back direction, and a backrest is attached to the back support rod.

By the way, conventional back support rods are generally formed by forming a sheet metal material into a channel shape or having pipe members arranged in parallel. Therefore, it is difficult to make the backrest exhibit high rigidity against forces that twist it.

Recently, however, back support rods have been constructed from a pair of solid square metal bars spaced apart on the left and right, and the base ends of these square bars are connected by welding joints. In addition to being connected via metal fittings, a bracket made of sheet metal is attached to the front face of the tip of both solid square bars, and the bracket is fixed to the front face of the solid square bar via a welded joint. is considered.

[Problem that the invention aims to solve] However, even if such a solid square bar is used,
If the bracket is made of sheet metal in order to reduce weight, there is still a problem in that it is difficult to provide sufficient rigidity against twisting of the backrest. In other words, as schematically shown in Fig. 8, when a plate-shaped bracket a is simply fixed to the front of a pair of solid square bars b, when a torsional force f is applied to the backrest c, In addition, while the bracket a undergoes bending deformation, each of the solid square bars b tends to undergo torsional deformation independently. As a result, the direction of the backrest c changes significantly.

In addition, heat is easily scattered internally in solid materials vertically and horizontally, so when welding the front surface of a solid square bar and a sheet metal bracket, the thinner bracket will mainly melt, and the solid square bar will melt. There is a tendency for this to lead to the phenomenon that it hardly dissolves. Therefore, problems may arise in the strength of the welded joint.

The present invention aims to solve these problems all at once.

[Means for solving the problem] The present invention is intended to achieve the above objectives. The following configuration is adopted.

That is, in the chair with a backrest according to the present invention, the back support rod is constituted by a pair of solid rectangular metal rods arranged at intervals on the left and right, and the base ends of the rectangular rods are welded together. The two solid square bars are connected via connecting fittings that are joined by the solid square bars, and a bracket having a bent piece that comes into contact with the front end surface is attached to the tip of each of the solid square bars, so that at least each of the solid square bars It is characterized in that three peripheral edges of the distal end surface of the bending piece are respectively joined to the lower surface of the bent piece through welded joints.

[Operation] According to such a configuration, the left and right solid square bars,
The connecting fittings and the bracket form a frame joined by a welded joint. Therefore, it goes without saying that it exhibits high strength against the backrest falling to the left or right.

Moreover, the tip surfaces of the left and right solid square bars are brought into contact with the bent piece of the bracket, and the three peripheral edges of the tip surfaces are fixed to the bent piece through welded joints. As long as the bent pieces do not buckle, the left and right solid rectangular bars will hardly be able to undergo torsional deformation individually. Therefore, even if a torsional force is applied to the entire backrest, high rigidity will be exhibited.

Further, the tip surface of the solid square rod is a place where heat applied from the outside cannot be internally scattered upward, and the peripheral edge of the tip surface exhibits thermal meltability similar to that of a sheet metal material. Therefore, the welded joint that joins the solid square bar and the bracket can be made to have high strength.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 7.

This chair with a backrest, as shown in Figure 4,
A seat 4 and a backrest 5, which are integrally constructed using an inner shell 2 and an outer shell 3, are disposed on a support unit 1.

As shown in FIG. 4, the support unit 1 includes a base 11 having leg blades projecting radially from the outer periphery of a central boss, a pedestal 12 erected at the center of this base 11, and this pedestal. 12 and a support base 13 connected to the upper end thereof. The support base 13 is made of aluminum die-casting, for example, and as shown in FIGS.
It has side walls 13b erected on both left and right edges of a. Both side walls 13b of this support base 13
A pair of left and right balance members 101 are respectively pivotally attached to the shafts. The balance member 101 is an elongated plate-like member extending back and forth, and its intermediate portion is rotatably attached to the support base 13 via a shaft 102. The rear ends of the left and right balance members 101 are rigidly connected to each other by a connecting fitting 103, and a back support rod 104 extends rearward and upward from the connecting part.
Further, on the support base 13, a seat support frame 105 is provided.
is arranged. As shown in FIGS. 4 and 6, the seat support frame 105 includes a frame-shaped top plate 105a and side plates 1 hanging from both left and right edges of the top plate 105a.
05b, and both side plates 10
5b is connected to the front ends of both side walls 13b of the support base 13 via the front link member 106, and the rear ends of the both side plates 105b are connected to the both balance members 101 via the rear link member 107. Connected to the rear end. That is, the left and right front link members 106 are attached to the front ends of these side plates 105b.
The upper pivot ends of these front link members 106 are pivotally connected via a shaft 108, and the lower pivot ends of both front link members 106 are pivotably attached to the side wall 13b of the support base 13 via a shaft 109. In addition, left and right rear link members 107 are attached to the rear end portions of both side plates 105b of the seat support frame 105.
The upper end of the is pivotally connected via a shaft 111, and
The lower ends of both rear link members 107 are pivotally connected to the rear end of the balance member 101 via a shaft 112. Elongated holes 113 extending back and forth are provided in the front ends of both the balance members 101, and the elongated holes 113 are slidably connected to a shaft 110 provided at the rear pivot point of the front link member 106. ing. An intermediate shaft 114 is installed in the middle part of the side wall of the support base 13, and a main spring 115 is stretched between the intermediate shaft 114 and the shaft 108.
The seat support frame 105 is elastically biased rearward. Further, an auxiliary spring 116 is wound around the shaft 109 so that the auxiliary spring 116 can bias the seat support frame 105 in the same direction. One end of the auxiliary spring 116 is locked by a spring force adjustment mechanism 117, and by changing the locking position, the biasing force of the auxiliary spring 116 can be adjusted.

Then, as shown in FIG. 5, horizontally long brackets 118 and 119 are fixed to the front end of the seat support frame 105 and the upper end of the back support rod 104, respectively, and the inner shell 2 is mounted on the horizontally long brackets 118 and 119. It is installed.

That is, the inner shell 2 is the seat corresponding part 2.
1 and a backrest corresponding portion 22 are integrally molded and are L-shaped in side view, and are made of elastically deformable synthetic resin such as polypropylene. At the same time, the backrest corresponding portion 22 is supported by the back support rod 104 via the horizontally long bracket 119.

On the other hand, the outer shell 3 has a seat corresponding portion 31.
and a backrest corresponding portion 32 are integrally molded to form an L-shape in side view, and are made of an elastically deformable synthetic resin such as polypropylene, and a portion near its periphery is bonded to the inner shell 2. There is.

A fixed shell 6 is disposed at a position to close the opening 33 of the outer shell 3, as shown in FIGS. 4 and 5.

Furthermore, an exterior material 8 is stretched over the front side of the inner shell 2 with a cushion material 7 interposed therebetween.

Here, the back support rod 104 in such a chair
The joining structure between the connecting fitting 103 and the horizontally long bracket 119 will be described in detail with reference to FIGS. 1 to 3.

The back support rod 104 is composed of a pair of solid rectangular metal rods 141 that are spaced apart from each other on the left and right sides. The base ends 141a of both of the solid square bars 141 are connected to each other via a connecting fitting 103 joined by welded joints 142 and 143. That is, as shown in FIGS. 1 and 3, the connecting fitting 103 is a metal plate bent into a U-shape, and the base end 101a of the balance member 101 is attached to the outer surface of the connecting fitting 103. . Balance member 101
A bent portion 101b that receives the lower surface of the solid square rod 141 is provided at the base end 101a of the rod. At the same time, the balance member 101 and the connecting fitting 10
3 through a welded joint 143. On the other hand, the horizontally long bracket 119 has a face plate 119a and a face plate 119, as shown in FIGS.
Upper edge reinforcement part 11 extending rearward and upward from the upper edge of a
9b and a lower edge reinforcing portion 119c extending rearward from the lower edge of the face plate 119a are integrally formed by pressing a sheet metal material.
Then, attach the center portion of the upper edge reinforcement portion 119b to the face plate 1.
A bent piece portion 119d is formed by deeply bending the portion 19a so as to be perpendicular to the portion 19a. and,
This horizontally long bracket 119 is attached to both the solid square bars 1
41, and the tip surface 1 of the solid square bar 141 is attached to the lower surface of the bent piece 119d.
41c is in contact with it. And each solid square bar 1
Three peripheral edges 141c ₁ , 1 of the tip surface 141c of 41
41c ₂ and 141c ₃ are respectively joined to the lower surface of the bent piece portion 119d via a welded joint 144. In addition, in this embodiment, the lower edge reinforcing portion 119c of the horizontally long bracket 119 and the solid square bar 141 are further added.
are additionally joined via a welded joint 145.

Next, the operation of this chair will be explained.

In the reference posture shown by solid lines in FIGS. 4 and 5, the backrest 5 is upright, and the seat 4 is held at the most retracted position. This standard posture is suitable for working, etc. When the user presses the backrest 5 backwards from this standard posture, the balance member 10 moves along with the backrest 5.
1 rotates rearward around a shaft 102 that serves as a fulcrum. As a result, the front end of the balance member 101 moves upward, and the front link member 106 is rotated forward. As a result, the seat support frame 105 moves forward, and the rear link member 1 supported by the rear end of the balance member 101
07 also rotates forward. At this time, the degree to which the entire rear link member 107 descends as the balance member 101 rotates is set to be greater than the degree that the shaft 111 at the upper pivot point rises due to the rotation of the rear link member 107. Therefore, the seat 4 apparently moves forward while gradually lowering its rear end, and reaches the resting position shown by the imaginary line in FIG. 5.

Although it can be operated and used as described above, according to this chair, the back support rod 104
The left and right solid square rods 141 and the connecting fittings 1
03 and the horizontally long bracket 119 form a frame joined by welded joints 142, 143, 144, and 145. Therefore, the backrest 5
Of course, it exhibits high strength against falling to the left or right.

Moreover, the tip surfaces 141 of the left and right solid square rods 141
c is brought into contact with the bent piece portion 119d of the horizontally long bracket 119, and the three peripheral edges 14 of the tip surface 141c are
1c ₁ , 141c ₂ , 141c ₃ are fixed to the lower surface of the bent piece portion 119d via the welded joint 144, so as long as the bent piece portion 119d does not buckle, the left and right solid square bars 141 can hardly be torsionally deformed individually. Therefore, even if a torsional force is applied to the entire backrest 5, high rigidity will be exhibited. That is, in the conventional case, as schematically shown in FIG. 8, when a torsional force f is applied to the backrest c,
While the bracket a deforms in the thickness direction, each of the solid square rods b tends to undergo torsional deformation, causing the backrest c to change direction significantly. In contrast, in the present invention, as schematically shown in FIG. 7, the tip surfaces 141c of both solid square bars 141 are rigidly connected to the bent piece portion 119d via a welded joint 144. , the tip 141b of the solid square rod 141
However, it becomes difficult to rotate in the torsional direction by itself, and the members at the bent piece portion 119b mutually reinforce each other to form a highly rigid structure. Therefore, even if some torsional force f acts on the backrest 5, the entire backrest 5 will not easily change direction.

Further, the tip surface 141c of the solid square rod 141 is a place where it is impossible for heat applied from the outside to be internally scattered upward, and the peripheral edge of the tip surface 141 has a thermal melting property similar to that of a sheet metal material. show. Therefore, the welded joint 144 that joins the solid square bar 141 and the oblong bracket 119 can be made to have high strength.

Note that the present invention is of course not limited to the embodiments described above, and can be applied to, for example, a chair in which the seat and backrest are constructed separately.

[Effects of the invention] Since the present invention has the above-mentioned configuration, it is possible to effectively improve the torsional rigidity of the backrest without increasing the thickness of the material. It is possible to provide a chair with a backrest that can easily increase the strength of the welded joint for joining the parts and ensure high reliability and durability.

[Brief explanation of the drawing]

Figures 1 to 7 show one embodiment of the present invention.
The figure is a perspective view showing the back support rod portion, Figure 2 is an enlarged perspective view showing the upper end portion of the back support rod from the back side, Figure 3 is a cross-sectional view showing the base end portion of the back support rod, and Figure 4 5 is a partially cutaway side view, and FIG. 5 is a side sectional view showing the inside.
FIG. 6 is a partially omitted plan sectional view, and FIG. 7 is a schematic plan view schematically showing the joint portion between the back support rod and the bracket. FIG. 8 is a schematic plan view corresponding to FIG. 7 for explaining the conventional example. 103... Connecting metal fittings, 104... Back support rod, 11
9... Bracket (horizontal bracket), 119d
...Bent piece part, 141...Solid square bar, 141b...
...Tip part, 141c...Tip surface, 141c ₁ , 14
1c ₂ , 141c ₃ ...side, 142, 143, 144
...Welded joint.

Claims (1)

[Scope of utility model registration request] The back support rod is composed of a pair of solid square metal bars arranged at intervals on the left and right, and the base ends of the square bars are connected to each other via a connecting fitting that is joined by a welded joint. At the same time, a bracket having a bent piece that comes into contact with the tip surface is attached to the tips of both of the solid square bars, and at least three peripheral edges of the tip surface of each of the solid square bars are welded together. A chair with a backrest, characterized in that the folding pieces are respectively joined to the lower surfaces of the folding pieces via the bending pieces.