JPH0257207A - Chair with back rest - Google Patents

Abstract

PURPOSE:To reduce the difference in resin density as little as possible between the vicinity of both side edges of an inner shell, a front edge and the vicinity of an upper edge by setting a resin filling part at the center part of the inner shell and slitting both sides of the resin filling part. CONSTITUTION:A resin filled into a die from a resin filling part 20 is guided to a protruding line in the die for forming slits 29 and flows toward the front edge 21a of a part 21 corresponding to a seat and toward the upper edge 22c of a part 22 corresponding to a back rest. Then, a part of the flow bypasses the lower ends 29a and the upper ends 29b of the slits 29 and is guided to left and right side edge 28a, of an inner shell 2. Accordingly, the length of a path from the resin filling part 20 to the front edge 21a and the upper edge 22c and the length of path from the resin filling part 20 to both side edges 28a are equalized: this produces no large difference in resin density between the vicinity of the side edge 28a, the front edge 21a and the vicinity of the upper edge. Accordingly, an inconvenience that an internal stress remains due to a contraction strain when the resin is hardened can be effectively suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a chair with a backrest, in which a seat and a backrest are integrally constructed using a synthetic resin inner shell.

[Prior Art] Conventionally, this type of chair with a backrest has an inner shell having a seat-corresponding part and a backrest-corresponding part, and an exterior material is stretched on the front side of the inner shell through a cushioning material. It is known that a cover is attached to the back side and the seat and backrest are integrated.

In this case, the seat-corresponding part of the inner shell is fixed to a floor support frame supported by a pillar, etc., and the backrest-corresponding part is fixed to a back support rod using bolts or the like. As the rod and the floor support frame move relative to each other, the inner shell is elastically deformed as appropriate.

By the way, when such an inner shell is integrally molded, a resin injection part is set in the center of the inner shell so that the molten resin injected into the mold spreads radially from the resin injection part.

[Problems to be Solved by the Invention] However, in an inner shell having a seat corresponding portion and a backrest corresponding portion, the distance from the front edge of the seat corresponding portion to the upper edge of the backrest corresponding portion is is much larger than the distance of Therefore, the distance from the resin injection part set at the center to the front edge of the seat corresponding part and the upper edge of the backrest corresponding part and the distance from the resin injection part to the side edge are largely different. Therefore, variations occur in the time it takes for the resin to reach each edge, and the pressure and curing time of the resin at each part vary. In other words, the resin density will be significantly different between the side edges where the resin arrives early and the leading and upper edges where the resin arrives later, and the resin will be adversely affected by shrinkage strain during the curing process. It's easy. Therefore, there is a problem that internal stress remains in the inner shell, and cracks occur during use, and the attachment portion is likely to be damaged.

The present invention aims to solve such problems.

[Means to solve the problem] The present invention has been made to achieve the above objects.

The following configuration is adopted.

That is, as schematically shown in FIGS. 1 and 2, the chair with a backrest according to the present invention has a synthetic resin inner that has a seat corresponding part (21) and a backrest corresponding part (22). The seat and backrest are integrally constructed using a shell (2), and a resin injection part (20 ), and slits (29) extending vertically on both left and right sides of the resin injection part (20).
It is characterized by having the following.

[Operation] According to such a configuration, when the inner shell (2) is injection molded using a mold (not shown), the resin injection part (
The resin injected into the mold from slit (29)
) and flows toward the leading edge and the upper edge (see arrow aSb). Then, part of the flow bypasses the lower end (29a) and upper end (29b) of the slit and is guided to the left and right side edges (28a) of the inner shell (see arrow C1d). Therefore, from the resin injection part (20) to the front edge (21a
) and the upper edge (22c), and the length of the path from the resin injection part (20) to the left and right side edges (28a) are equalized, and the length of the path from the resin injection part (20) to the left and right side edges (28a) is equalized,
There is no large difference in resin density between a) and the vicinity of the upper edge (22c).

Note that the resin that has bypassed the lower end (29a) of the slit (29) and the resin that has bypassed the upper end (29b) of the slit (29) meet to form a so-called weld line (L) on the outside of the slit (29). However, according to the configuration of the present invention, this weld line (L) is connected to the inner shell (2).
) can be located at the boundary part (28) between the seat corresponding part (21) and the backrest corresponding part (22). This boundary part (28) is not a part that is fixed to metal fittings such as a floor support frame or back support rod, so there is a weld line (L) in this part.
), weld line (L)
It is possible to prevent the problem that cracks are likely to occur due to alignment of the fixing position with the bolt or the like.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 3 to 8.

The chair with a backrest of this embodiment is as shown in Fig. 3.
A seat 4 and a backrest 5 integrally formed using an inner shell 2 and an outer shell 3 are disposed on a support unit 1.

As shown in FIG. 3, the support unit 1 has a central boss portion 1.
A base 11 having five leg blades 11b radially protruding from the outer periphery of the base 1a, a pedestal 12 erected on the central boss portion 11a of the base 11, and a support continuous to the upper end of the pedestal 12. A base 13 is provided. And this support base 1
A balance member 101 is pivoted on both sides of 3. 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. Furthermore, a floor support frame 105 is disposed on the support base 13. The front end of the floor support frame 105 is connected to the front end of the support base 13 via the front link member 106, and the rear end is connected to the rear end of both balance members 101 via the rear link member 107. are doing. That is, the upper pivot ends of the left and right front link members 106 are pivotally attached to the front end of the floor support frame 105 via the shaft 108, and the lower pivot ends of both front link members 106 are pivoted to the support base 13. It is pivotally connected via 109. Further, the upper pivot ends of left and right rear link members 107 are pivotally connected to the rear end portions of the floor support frame 105 via shafts 111, and the lower pivot ends of these post-rain link members 107 are connected to the balance member 101.
It is pivotally connected to the rear end of the shaft 112 via a shaft 112. A long hole 113 extending back and forth is provided at the front end of both the balance members 101.
, and their elongated holes 113 are slidably connected to a shaft 110 provided at the rear pivot point of the front link member 106. An intermediate shaft 114 is installed in the middle part of the side wall of the support base 13, and this intermediate shaft 114 and the shaft 108
A main spring 115 is stretched between the floor support frame 1 and
05 is elastically biased rearward. Further, an auxiliary spring 116 is wound around the shaft 109 so that the auxiliary spring 116 can bias the floor 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 auxiliary spring 1
16 can be adjusted.

The front end of the floor support frame 105 and the back support rod 10
4, as shown in FIG.
8. The inner shell 2 is attached to 119.

As shown in FIGS. 4 to 8, the inner shell 2 is formed by integrally molding a seat corresponding portion 21 and a backrest corresponding portion 22, and is shaped like an elastically deformable material such as polypropylene. Made of synthetic resin. The seat-corresponding portion 21 has a shape in which the right and left side edges and the center portion are slightly raised, and a nut 23 is fixed to the front side near both side edges. And the horizontally long bracket 11
The inner shell 2 is attached to the floor support frame 10 by means of bolts 24 that pass through the vicinity of both ends of the inner shell 8 and are screwed onto the nuts 23.
It is attached to 5. In addition, in this embodiment, a nut 25 is also fixedly installed in the central front part of the inner shell 2, and the nut 25 is inserted through the front end of the floor support frame 105.
The attachment strength of the inner shell 2 is increased by an auxiliary bolt (not shown) screwed into the inner shell 2. The backrest corresponding portion 22 has a shape in which left and right side edges 22a are slightly curved in the forward direction, and nuts 26 are fixedly installed in the vicinity of both side edges 22d at approximately the same height as the so-called backrest point. . The inner shell 2 is connected to the back support rod 104 by screwing bolts 27 passing through the vicinity of both ends of the horizontally long bracket 119 into the nuts 26. The boundary portion 28 between the seat corresponding portion 21 and the backrest corresponding portion 22 of the inner shell 2 has a degree of curvature of approximately zero in the direction in which the left and right side edges 28a move forward, and has a semicircular arc shape in side view. It is curved so that it bulges out backwards. Two parallel slits 29 extending vertically are provided in this boundary portion 28. The lower end 29a side of both of these slits 29 extends to the rear of the seat corresponding portion 21, and the upper end 29b side extends to a position higher than the backrest point of the backrest corresponding portion 22,
A portion 22b located between these slits 29 protrudes forward.

In addition, when integrally molding this inner shell 2, the resin injection part 20 is located at the center of the inner shell 2, that is,
Boundary portion 2 between seat corresponding portion 21 and backrest corresponding portion 22
8, it is set at an intermediate position in the left-right direction. Therefore, the slits 29 are provided on both sides of this resin injection part 20.
will be located.

On the other hand, as shown in FIGS. 3 to 6, the outer shell 3 is formed by integrally molding a seat-corresponding part 31 and a backrest-corresponding part 32, and is shaped like a rectangular shape when viewed from the side, and is made of elastically deformable material such as polypropylene. Made from possible synthetic resin. The seat-corresponding portion 31 has a spherical shape that bulges downward, and is provided with a rectangular opening 33 that is long in the front and back at the center thereof.

The backrest corresponding portion 32 has a shape in which left and right edges 32a are curved in a forward direction, and the degree of curvature increases as the upper edge 32b approaches the backrest point.

The degree of curvature of the outer shell 3 near the backrest point is greater than the degree of curvature of the inner shell 2 at the same cross-sectional position. In addition, this outer shell 3
The boundary portion 34 between the seat corresponding portion 31 and the backrest corresponding portion 32 has a degree of curvature of approximately zero in the direction in which the left and right side edges 34a move forward, and bulges rearward in a semicircular arc shape when viewed from the side. It is curved to look like this. A portion near the base end of the backrest corresponding portion 32 in this outer shell 3,
That is, the upper part of the boundary part 34 is brought close to the part of the inner shell 2 near the base end of the backrest corresponding part 22, that is, the upper part of the boundary part 28.

The attachment structure of the outer shell 3 to the inner shell 2 is as follows. First, a portion near the front edge and a portion near the side edge of the seat corresponding portion 31 of the outer shell 3 are removably screwed to a portion near the front edge and a side edge of the inner shell 2.

The boundary portion 34 of the outer shell 3 is not connected to the boundary portion 28 of the inner shell 2. The side edge vicinity portion 32C and the upper edge vicinity portion 32d of the backrest corresponding portion 32 of the outer shell 3 have an engaging structure using claws. Specifically, as shown in FIG. 6, the outer shell 3 has an upward mold 301 bent in a crescent shape when viewed from the side near the side edge 32c, and a first inward mold 302 having an undercut portion on the inside. and a second inward-facing type 30 that also has an undercut portion on the inside.
3 are protruded from the bottom at predetermined intervals, and a downward mold 304 having an undercut portion on the lower side is integrally protruded from the upper edge vicinity portion 32d. In addition, inner shell 2
Engagement holes 201.202.203.204 are bored in portions corresponding to the winter melon 30L 302.303.304. Then, the upward mold 301 is engaged with the upper edge of the corresponding engagement hole 201 so as to be movable in the vertical direction by a required amount, and both the inward claws 302 and 303 are connected to the opening of the corresponding engagement hole 202 and 203. Edge portion 202a.

203a, and the downward mold 304 is engaged with the lower band portion 204a of the opening edge of the corresponding engagement hole 204 by utilizing elastic deformation of each member. In addition, the first introvert type 3
02 has a straight wall shape extending in the vertical direction, and the opening edge portion 202a of the corresponding engagement hole 202 is formed in a straight line shape, and even in the engaged state, the inward type 30
2 can slide in the vertical direction with respect to the engagement hole 202. Then, a tongue piece 202c that can be deformed in the thickness direction is integrally provided to project from the outer part of the opening edge of the engagement hole 202, and the free end of the tongue piece 202c is connected to the part closer to the opening edge 202a.
The inner mold 302 is brought into contact with the outer surface of the inward mold 302, which is engaged with the inner mold 302.

The second inward mold 303 has a half-moon shape similar to the downward mold 304, but the second inward mold 303 also has a hole in the engagement hole 20 so that it can move slightly up and down in the engaged state.
3 dimensions are set. These claws 301.302.
303.304 and corresponding engagement holes 201.202.2
The engagement depth and engagement direction with 03.204 are set so that they will not come off during normal use.

A fixed shell 6 is disposed at a position to close the opening 33 of the outer shell 3, as shown in FIGS. 3, 4, and 6. Thus, this fixed shell 6 is removably attached to the lower surface of the support base 13 of the support unit 1 using bolts 66.

Note that an exterior material 8 is stretched on the front side of the inner shell 2 with a cushion material 7 interposed therebetween.

The peripheral edge of the exterior material 8 is guided to the back side of the inner shell 2 and fixed with a tacker or the like (not shown).

Next, the operation of this chair will be explained.

In the reference posture shown by solid lines in FIGS. 3 and 4, the backrest 5 is erected 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 backrest 5 and the
The balance member 101 rotates rearward about 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 107 supported by the rear end of the balance member 101 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 sinking its rear end, and reaches the resting position shown by the imaginary line in FIG. 4.

The inner shell 2 is elastically deformed following the above-mentioned operation, and the inner shell 2 has the resin injection part 20 set in the center and slits 29 on both sides of the resin injection part 20. Therefore, when integrally molding this inner shell 2, each edge 21a, 22a of the resin is
, 28a can be uniformly introduced. That is, the resin injected into the mold from the resin injection part 20 is guided by the protrusion in the mold for forming the slit 29, and is directed toward the front edge 21a of the seat corresponding part 21 and the backrest corresponding part 22. It flows toward the upper edge 22c. Then, a part of the flow bypasses the lower end 29a and upper end 29b of the slit 29, and passes through the left and right side edges 22 of the inner shell 2.
a, you will be guided to part 28a. Therefore, the length of the path from the resin injection part 20 to the front edge 21a and the upper edge 22c and the length of the path from the resin injection part 20 to the left and right side edges 28a are made uniform, and the length of the path from the resin injection part 20 to the left and right side edges 28a is equalized. There is no large difference in resin density between the upper edge 22c and the upper edge 22c. Therefore, it is possible to effectively suppress the problem that internal stress remains due to shrinkage strain when the resin hardens.

Then, the resin bypassed the lower end 29a of the slit 29,
The resin that has bypassed the upper end 29b of the slit 29 joins together to form a so-called weld line L on the outside of the slit 29.
Boundary part 2 between the seat corresponding part 21 and the backrest corresponding part 22
It can be located at 8. Such boundary portion 28 is
As mentioned above, this is not the part that is fixed to the horizontally long bracket 118 of the seat support frame 105 or the horizontally long bracket 119 of the back support rod 104, so if the weld line L can be located in this part, the weld line L and the bolt 24. 2
It is also possible to prevent the problem that cracks and the like are likely to occur due to alignment of the fixing position by 7.

It should be noted that the present invention is of course not limited to the embodiments described above, and may be applied to those in which the seat simply swings up and down relative to the support unit, or in which the back support rod is pivoted to the support base of the support unit. The present invention can also be applied to chairs that have only a support rod or a chair that does not have a back support.

Further, in the above embodiment, a case has been described in which only the portion of the inner shell located between the slits is made to protrude forward, but the present invention also includes a case that does not have such a protruding form. However, if the above embodiment is adopted, on the back side of the portion located between the slits,
Since a space is formed to accommodate the back support rod, the degree of freedom in shaping the outer shell can be increased.

Further, the outer shell that covers the back side of the inner shell does not need to be integrally molded, and may be divided into a plurality of pieces.

[Effects of the Invention] Since the present invention has the above configuration, it is possible to minimize the difference in resin density between the vicinity of both left and right edges of the inner shell and the vicinity of the front edge and upper edge. It is possible to effectively suppress the problem of hardening with residual internal stress due to shrinkage strain. Therefore, it is possible to obtain the special effect that there is little deformation and that it is difficult to cause cracking or damage even after long-term use.

Moreover, the weld line of the resin can be located at the boundary between the seat corresponding part and the backrest corresponding part.
There is no possibility that the fastening part for attaching the inner shell to the seat support frame or back support rod will match the weld line. Therefore,
It is possible to reliably prevent the problem that a concentrated load acts on the weld line portion and cause it to be easily damaged, and from this point of view as well, high durability can be ensured.

[Brief explanation of the drawing]

1 and 2 are for clearly showing the structure of the present invention. FIG. 1 is a schematic side sectional view of the inner shell, and FIG. 2 is a view taken in the direction of the ■ arrow in FIG. 1. 3 to 8 show one embodiment of the present invention, in which FIG. 3 is a partially cutaway side view, FIG. 4 is a side sectional view showing the inside, and FIG.
The figure is a partially omitted plan sectional view, FIGS. 6 and 7 are exploded perspective views, and FIG. 8 is a view taken in the direction of the ■ arrow in FIG. 6. 1... Support unit 3... Outer shell 5... Backrest 21... Seat corresponding portion 29... Slit 2... Inner shell 4... Seat 20... Resin injection part 22...・Backrest compatible part

Claims (1)

[Claims] A chair with a backrest in which a seat and a backrest are integrally constructed using a synthetic resin inner shell having a seat-corresponding part and a backrest-corresponding part; A chair with a backrest characterized by having a resin injection part when integrally molded, and having slits extending vertically on both left and right sides of the resin injection part.