JPH0793897B2 - Chair with backrest - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a chair with a backrest in which a seat and a backrest are integrally formed by using an inner shell made of synthetic resin.

[Prior Art] Conventionally, as this type of chair with a backrest, an inner shell having a seat-corresponding portion and a backrest-corresponding portion is provided, and an exterior material is stretched on the front side of the inner shell via a cushion material. It is known that a seat and a backrest are integrally formed by mounting a cover on the back side.

This is because the seat-corresponding portion of the inner shell is fixed to a seat receiving frame supported by a pedestal, and the backrest-corresponding portion is fixed to a back support rod using bolts, respectively. The inner shell is appropriately elastically deformed in accordance with the relative movement of the rod and the seat receiving frame.

By the way, in the case of integrally molding such an inner shell, a resin injection portion is set in the center thereof, and the molten resin injected into the mold is spread radially from the resin injection portion.

[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 between left and right side edges. Much larger than the distance. 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 greatly different. Therefore, the arrival time of the resin at each edge portion varies, and the pressure of the resin and the curing time at each portion differ. That is, the resin density is significantly different between the side edges where the resin arrives early and the leading edge and the upper edge where the resin arrives late, and the resin is adversely affected by shrinkage strain during the process of curing. easy. Therefore, there is a problem that internal stress remains in the inner shell, and cracks may occur during use, or damage may easily occur at the mounting portion.

The present invention aims to solve such problems.

[Means for Solving the Problems] The present invention is intended to achieve the above objects. It adopts the following configuration.

That is, a chair with a backrest according to the present invention, as schematically shown in FIGS. 1 and 2, is a synthetic resin inner having a seat-corresponding portion (21) and a backrest-corresponding portion (22). A seat and a backrest are integrally formed by using a shell (2), and a resin injection part (20) for integrally molding the inner shell (2) is formed at the center of the inner shell (2). ) And its resin injection part (20)
It is characterized in that slits (29) extending vertically are provided on both left and right sides of the.

[Operation] According to such a configuration, when the inner shell (2) is injection-molded by using a mold (not shown), the resin injected from the resin injection part (20) into the mold has a slit (29 )
Guided by the ridges in the mold for forming, flow toward the front edge direction and the upper edge direction (see arrows a and b). Then, a part of the flow bypasses the lower end (29a) and the upper edge (29b) of the slit, and the left and right side edges (28
It will be guided to part a) (see arrows c and d). Therefore, from the resin injection part (20) to the front edge (21a) and the upper edge (2
2c) and the length of the path reaching the left and right side edges (28a) from the resin injection part (20) are equalized, and the vicinity of the side edge (28a) and the front edge (21a) and the upper edge ( There is no great difference in the resin density between 22c) and its vicinity.

The resin bypassing the lower end (29a) of the slit (29) and the resin bypassing the upper end (29b) of the slit (29) meet to form a so-called weld line (L) outside the slit (29). However, according to the configuration of the present invention, the weld line (L) has a boundary portion (2) between the seat corresponding portion (21) and the backrest corresponding portion (22) of the inner shell (2).
8) can be located. Such borders (28)
Is not a part that is fixed to the metal fittings such as the seat receiving frame and the back support rod, so if the weld line (L) can be located in this part, it will become It is possible to prevent the problem that cracks and the like tend to occur due to the coincidence with each other.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 3 to 8.

The chair with a backrest according to this embodiment is, as shown in FIG.
On the support unit 1, a seat 4 and a backrest 5 that are integrally formed by using an inner shell 2 and an outer shell 3 are arranged.

As shown in FIG. 3, the support unit 1 has a central boss portion 11
A base 11 formed by radially projecting five leg blades 11b on the outer periphery of a, and a pedestal 1 standing on a central boss portion 11a of the base 11.
2 and a support base 13 continuously provided on the upper end of the pedestal 12. The balance members 10 are provided on both sides of the support base 13.
1 is attached to each. The balance member 101 is an elongated plate member extending in the front-rear direction, and an intermediate portion thereof 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 attached to each other by a connecting fitting 103, and the back support rod 104 extends rearward and upward from the connecting portion. In addition, a seat receiving frame is provided on the support base 13.
105 is provided. The front end portion of the seat receiving frame 105 is connected to the front end portion of the support base portion 13 via the front link member 106, and the rear end portion thereof is connected to the rear end portion of the both balance members 101 via the rear link member 107. is doing. That is, the upper pivoting ends of the left and right front link members 106 are pivotally attached to the front end portions of the seat receiving frames 105 via the shafts 108, and the lower pivoting ends of the front link members 106 are pivotally attached to the support base portion 13. 109
Is pivoted through. Further, the upper pivoting ends of the left and right rear link members 107 are pivotally attached to the rear end portion of the seat receiving frame 105 via shafts 111, and the lower pivoting ends of the rear link members 107 are attached to the rear of the balance member 101. It is pivotally attached to the end through a shaft 112. Then, long holes 113 extending in the front-rear direction are provided at the front ends of the both balance members 101, and the long holes 113 are continuously slidably connected to a shaft 110 provided at a rear pivot point of the front link member 106. ing. An intermediate shaft 114 is installed in the middle 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 to elastically bias the seat receiving frame 105 rearward. is doing. In addition, the shaft 109 has an auxiliary spring 116.
And the auxiliary spring 116 is used to wind the seat receiving frame 105.
Are urged in the same direction. One end of the auxiliary spring 116 is locked by a spring force adjusting mechanism 117, and the biasing force of the auxiliary spring 116 can be adjusted by changing the locking position.

Then, as shown in FIG. 5, a horizontally long bracket 11 is provided at the front end of the seat receiving frame 105 and the upper end of the back support rod 104, respectively.
8 and 119 are fixed, and the inner shell 2 is attached to the horizontally long brackets 118 and 119.

As shown in FIGS. 4 to 8, the inner shell 2 is an L-shaped side view formed by integrally molding a seat-corresponding portion 21 and a backrest-corresponding portion 22, and is elastically deformable such as polypropylene. Made of synthetic resin. Seat corresponding part 21
Has a shape in which the left and right side edge portions and the central portion are slightly lifted, and a nut 23 is fixedly attached to a front portion near both side edge portions. Then, the inner shell 2 is attached to the seat receiving frame 105 by the bolts 24 which are provided by penetrating the vicinity of both ends of the horizontally long bracket 118 and screwed to the nut 23. In this embodiment, the nut 25 is fixed to the front portion of the center of the inner shell 2, and the seat receiving frame 105
The mounting strength of the inner shell 2 is enhanced by an auxiliary bolt (not shown) which penetrates the front end of the and is screwed to the nut 25 thereof. The backrest-corresponding portion 22 has a shape in which the left and right side edges 22a are slightly curved in the forward direction, and a nut 26 is fixedly attached to both side edge neighboring portions 22d at a position substantially the same height as the so-called backrest point. And the horizontal bracket
Insert the bolt 27 that penetrates the vicinity of both ends of 119 into the nut 26
This inner shell 2 can be attached to the back support rod by
Connected to 104. 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 in the direction in which the left and right side edges 28a are in the forward direction set to substantially zero, and has a semicircular arc shape in side view. However, it is curved so that it bulges backward. Then, the boundary portion 28 is provided with two parallel slits 29 extending vertically. The lower ends 29a of these slits 29 extend to the rear of the seat-corresponding portion 21, and the upper ends 29b extend to a position higher than the backrest point of the backrest-corresponding portion 22, and between these slits 29. The positioned portion 22b is projected forward.

When the inner shell 2 is integrally molded, the resin injecting portion 20 is set at an intermediate position in the left-right direction at the center of the inner shell 2, that is, the boundary portion 28 between the seat corresponding portion 21 and the backrest corresponding portion 22. I am doing it. Therefore, the slits 29 are located on both sides of the resin injection part 20.

On the other hand, the outer shell 3 is an L-shaped side view formed by integrally molding a seat-corresponding portion 31 and a backrest-corresponding portion 32, as shown in FIGS. Made of possible synthetic resin. The seat-corresponding portion 31 has a spherical shape that bulges downward, and has a rectangular opening 33 that extends in the front-rear direction in the center thereof.
The backrest-corresponding portion 32 has a shape in which the left and right side edges 32a are curved in a forward direction, and the degree of curvature is set to increase as the backrest point is approached from the upper edge 32b. The degree of curvature of the outer shell 3 near the backrest point is made larger than the degree of curvature of the inner shell 2 at the same cross-section position. In addition,
The boundary portion 34 of the seat-corresponding portion 31 and the backrest-corresponding portion 32 of the outer shell 3 is set to have a degree of curvature in the direction in which the left and right side edges 34a are protruded to substantially zero, and has a semicircular arc shape in a side view. It is curved so that it bulges backward. Then, a portion of the outer shell 3 near the base end of the backrest corresponding portion 32, that is, the upper portion of the boundary portion 34 is placed on a portion of the inner shell 2 near the base end of the backrest corresponding portion 22, that is, the upper portion of the boundary portion 28. Are approaching.

The attachment structure of the outer shell 3 to the inner shell 2 is as follows. First, the vicinity of the front edge and the vicinity of the side edge of the seat-corresponding portion 31 of the outer shell 3 are
It is screwed to the front edge vicinity part and the side edge vicinity part so as to be removable from the outside. 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 with a claw. Specifically, as shown in FIG. 6, an upward claw 301 that bends in an L shape in a side view in a side edge vicinity portion 32c of the outer shell 3 and a first inward claw 302 that has an undercut portion inside. And a second inward claw 303 which also has an undercut portion on the inner side thereof and which protrudes in order from the bottom at predetermined intervals, and a downward claw 304 which has an undercut portion on the lower side in the upper edge vicinity portion 32d. Are projected integrally. Also, each of the claws of the inner shell 2
Engagement holes 201, 20 at the portions corresponding to 301, 302, 303, 304
2, 203, 204 are drilled. Then, the upward claw 301 is engaged with the upper edge portion of the corresponding engaging hole 201 so as to be movable in the vertical direction by a required amount, and the both inward claws 302, 303 are opened in the corresponding engaging holes 202, 203. The inward edge portions 202a and 203a and the downward claw 304 are engaged with the opening edge lower portion 204a of the corresponding engaging hole 204 by utilizing elastic deformation of the members. The first inward claw 302 has a straight wall shape extending in the vertical direction, and the opening edge inner portion 202a of the engaging hole 202 corresponding to the first inward claw 302 is formed in a linear shape, and even in the engaged state. , Is brought into contact with the outer surface of the inward claw 302. The second inward claw 302 can slide in the vertical direction with respect to the engagement hole 202. Then, a tongue piece 202c that is deformable in the thickness direction is integrally projected from the outer edge portion of the opening of the engaging hole 202, and the free end of the tongue piece 202c engages with the inner edge portion 202a of the opening edge. The claw 302 is brought into contact with the outer surface of the claw 302. Second inward claw 303
Has a half-moon shape similar to the downward claw 304, but the size of the engagement hole 203 is set so that the second inward claw 303 can also move slightly in the vertical direction in the engaged state. is there.
Each engaging hole 20 corresponding to these claws 301, 302, 303, 304
The engagement depth and the engagement direction with 1, 202, 203, and 204 are set so as not to be disengaged in a normal use state.

At a position where the opening 33 of the outer shell 3 is closed,
As shown in FIGS. 3, 4, and 6, the fixed shell 6
Are installed. The fixed shell 6 is detachably attached to the lower surface of the support base 13 of the support unit 1 by using the bolt 66.

An exterior material 8 is stretched on the front side of the inner shell 2 with a cushion material 7 interposed therebetween. The peripheral portion of the exterior material 8 is guided to the back surface side of the inner shell 2 and fixed by a tacker or the like (not shown).

Next, the operation of this chair will be described.

In the reference posture shown by the solid line in FIGS. 3 and 4, the backrest 5 stands up and the seat 4 is held in the rearmost retracted position. This standard posture is suitable for performing work and the like. When the user presses the backrest 5 rearward with his / her back from this reference posture, the balance member 101 pivots rearward with the backrest 5 around the shaft 102 serving 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 receiving 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 with the rotation of the balance member 101 is set to be larger than the degree to which the shaft 111 at the upper pivot point thereof rises due to the rotation of the rear link member 107. Therefore, the seat 4 apparently moves forward while gradually retracting the rear end, and reaches the resting position shown by the imaginary line in FIG.

The inner shell 2 will be elastically deformed following the above operation, but the inner shell 2 has its resin injection part 20 set at the center thereof and slits 29 are provided on both sides of the resin injection part 20. Therefore, when the inner shell 2 is integrally molded, the resin can be uniformly introduced into the respective edge portions 21a, 22a, 28a. That is, the resin injected from the resin injecting section 20 into the mold is guided by the ridges in the mold for forming the slits 29, and the seat corresponding portion 21.
Flows toward the front edge 21a and toward the upper edge 22c of the backrest corresponding portion 22. And a part of the flow is slit 29.
It bypasses the lower end 29a and the upper end 29b of the inner shell 2 and is guided to the left and right side edges 22a, 28a of the inner shell 2. Therefore, the length of the path from the resin injection part 20 to the front edge 21a and the upper edge 2c and the length of the path from the resin injection part 20 to the left and right side edges 28a are equalized, and the vicinity of the side edge 28a and the front edge 21a. Also, there is no great difference in the resin density between the vicinity of the upper edge 22c. Therefore, it is possible to effectively suppress the problem that internal stress remains due to shrinkage strain when the resin is cured.

Then, the resin bypassing the lower end 29a of the slit 29 and the resin bypassing the upper end 29b of the slit 29 meet to form the slit 2
A so-called weld line L is formed outside of 9,
The weld line L can be located at the boundary portion 28 between the seat corresponding portion 21 and the backrest corresponding portion 22 of the inner shell 2. Since the boundary portion 28 is not fixed to the horizontal bracket 118 of the seat receiving frame 105 or the horizontal bracket 119 of the back support rod 104 as described above, if the weld line L can be located at this portion, the weld line L can be positioned. It is also possible to prevent a problem that the line L and the fastening positions of the bolts 24 and 27 coincide with each other and cracks or the like are likely to occur.

It should be noted that the present invention is not limited to the above-described embodiments, and the seat simply swings up and down with respect to the support unit, and the back support rod is pivotally attached to the support base of the support unit. The present invention can also be applied to a chair that has just been opened or a chair that does not have a back support rod.

Further, in the above-described embodiment, the case where only the portion of the inner shell located between the slits is extruded to the front has been described, but the present invention also includes those that do not have such an extruded form. However, according to the above-described embodiment, since the space for accommodating the back support rod is formed on the back side of the portion located between the slits, the degree of freedom in shaping the outer shell can be increased. .

Furthermore, the outer shell that covers the back surface side of the inner shell does not have to be an integrally molded product, and may be divided into a plurality of pieces.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it is possible to minimize the difference in resin density between the left and right side edges of the inner shell and the front and upper edges thereof. It is possible to effectively suppress the problem of hardening due to shrinkage strain while internal stress remains. Therefore, it is possible to obtain a special effect that deformation is small and cracking or damage is less likely to occur even after long-term use.

Moreover, since the resin weld line can be located at the boundary between the seat-corresponding portion and the backrest-corresponding portion,
There is no possibility that the weld line and the fastening portion for attaching the inner shell to the seat receiving frame or the back support rod may coincide with each other. for that reason,
It is possible to surely prevent the problem that concentrated load acts on the weld line portion to easily break the weld line portion, and also from this point, high durability can be secured.

[Brief description of drawings]

1 and 2 are for clarifying the configuration of the present invention. FIG. 1 is a schematic side sectional view of the inner shell, and FIG. 2 is a view taken along the arrow II in FIG. 3 to 8 show an embodiment of the present invention, FIG. 3 is a partially cutaway side view, FIG. 4 is a side sectional view showing the inside, and FIG. Figures 6, 6 and 7 are exploded perspective views and Figure 8 is
FIG. 8 is a view on arrow VIII in the figure. 1 ... Support unit, 2 ... Inner shell 3 ... Outer shell, 4 ... Seat 5 ... Backrest, 20 ... Resin injection part 21 ... Seat corresponding part, 22 ... Backrest corresponding part 29 ... Slit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masamitsu Miyashita, 137, Miyata-mura, Kamiina-gun, Nagano Prefecture Takano Co., Ltd. ) Inventor Mitsuyoshi Katagiri 137, Miyata-mura, Kamiina-gun, Nagano Takano Co., Ltd. (56) References JP-A-60-45309 (JP, A)

Claims (1)

[Claims] 1. A chair with a backrest in which a seat and a backrest are integrally formed by using a synthetic resin inner shell having a seat-corresponding portion and a backrest-corresponding portion, and the center of the innershell. A chair with a backrest, characterized in that a resin injection portion for integrally molding the inner shell is set, and slits extending vertically are provided on both left and right sides of the resin injection portion.