Mold for Skin Covered Foamed Plastic Molding

1. Field of the Invention

The present invention relates to a mold for foamed plastic molding suitable for molding a foamed plastic article such as to be used for car seat cushions and seat backs in conjunction with skin covers and, more particularly, to such a skin covered foamed plastic molding which utilizes a middle mold between an upper mold and a lower mold.

2. Description of the Background Art

Car seat cushions and seat backs have been made of a pad member covered by a skin cover. The pad member and the skin cover used to be manufactured separately and combined together later, but it has become fashionable to manufacture a skin covered pad member altogether by forming foamed plastic in a skin cover laid over a mold, so that the process of combining at a later time may be omitted.

However, the contemporary car seats tend to have large side support portions with large curving so that it becomes difficult to place the skin cover neatly over the mold. As a consequence, in order to obtain a skin covered pad member of desired shape it is necessary for the skin cover to be pinned down or taped to the mold, which is an additional complication in the manufacturing process.

To cope with such problems, a mold 1 as shown in FIG. 1, comprising a lower mold 2, an upper mold 3, and a middle mold 4 to be placed in between the former two is used frequently. In this mold 1, an upper portion 6 of the lower mold 2 is openable by means of a hinge 5. An edge 8a of a skin cover 8 is pinched between an end of this openable upper portion 6 and an extended portion 7 of the middle mold 4. The upper mold 3 is placed on top of the openable upper portion 6 of the lower mold 2 and of the middle mold 4.

However, in such a conventional mold 1, the middle mold 4 is attached on one side of the lower mold 2, and in addition the upper mold 3 is placed on top of the upper portion 6 of the lower mold 2 as shown in FIG. 1, so that a great amount of pressure is exerted on the lower mold 2, which can lead to a damage or deformation of the lower mold 2.

Also, since the upper portion 6 of the lower mold 2 is attached by the hinge 5, shielding at the hinge 5 cannot be as complete as that between the upper portion 6 of the lower mold 2 and the upper mold 3, so that liquid foamed resin may penetrate into the skin cover 8 as a result of gaseous leakage, and consequently an amount of such penetration becomes uncontrollable.

It is therefore an object of the present invention to provide a mold for skin covered foamed plastic molding which utilizes a middle mold to be placed between an upper mold and a lower mold, capable of avoiding an excessive amount of pressure to be exerted on the upper portion of the lower mold so that the durability of the lower mold can be improved, and preventing gaseous leakage so that the penetration of the liquid foam resin to be poured on a skin cover becomes controllable.

This object of the present invention is achieved by providing a mold for skin covered foamed plastic molding, comprising a lower mold having a molding surface and a base, where a skin cover is to be placed over the molding surface, and where liquid foam resin is to be poured onto the skin cover; an upper mold to be closed over the lower mold, having extended side portions which can reach the base of the lower mold when assembled such that the extended side portions can support the upper mold by themselves; and a middle mold to be placed between the upper mold and the lower mold.

Other features and the advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

FIG. 1 is a partial cross sectional view of a conventional mold for skin covered foamed plastic molding.

FIG. 2 is an expanded view of one embodiment of a mold for skin covered foamed plastic molding according to the present invention.

FIG. 3 is a partial cross sectional view of the mold for skin covered foamed plastic molding of FIG. 2.

FIG. 4(A) is a perspective view of one embodiment of an upper mold for the mold for skin covered foamed plastic molding of FIG. 2.

FIG. 4(B) is a perspective view of one embodiment of a middle mold for the mold for skin covered foamed plastic molding of FIG. 2.

FIG. 5(A) is a perspective view of another embodiment of an upper mold for the mold for skin covered foamed plastic molding of FIG. 2.

FIG. 5(B) is a perspective view of another embodiment of a middle mold for the mold for skin covered foamed plastic molding of FIG. 2.

Referring now to FIGS. 2 and 3, there is shown one embodiment of a mold for skin covered foamed plastic molding according to the present invention.

In this embodiment, a mold 11 comprises a lower mold 12, an upper mold 13 to be placed over the lower mold 12, and a middle mold 14 to be inserted between the lower mold 12 and the upper mold 13. Bottom views of the upper mold 13 and the middle mold 14 are also shown in FIGS. 4(A) and 4(B), respectively.

Side portions 17 of the lower mold 12 are openable by means of lower hinges 15b and upper portions 16 at top and side edges of the lower mold 12, with approximate L-shape cross section, are openable by means of upper hinges 15a. There is a pair of holes 19 on a bottom surface of the top side of the lower mold 12 which receives a pair of supporting rods 18 of the middle mold 14. This pair of supporting rods 18 can also provide holes for receiving supporting rods of a head rest to be attached to a manufactured seat, if necessary. On a bottom of the lower mold 12 there is a wedge 50. Side portions 21 of the bottom of the lower mold 12 and bottoms of side portions 22 of the middle mold 14 form curved portions corresponding to side support portions of a seat cushion or a seat back to be manufactured. At two bottom side corners of the lower mold 12 there are indents 31 which receive support edges 32 of the middle mold 14. The middle mold 14 has a hollow 34 formed by a wall 34a and around this hollow 34 there is a ridge or hedge 24, except for a bottom side 37 of the middle mold 14. The upper mold 13 has a depression or bent 36 formed by a side wall 36a and a bottom face 36b which is to be engaged into the hollow 34 of the middle mold when assembled such that the bottom face 36b becomes a part of the molding surface corresponding to a back side of a seat cushion or a seat back to be manufactured. The side wall 36a of the upper mold 13 and the wall 34a of the middle mold 14 have slopes to facilitate easy engagement. Side portions 43 of the upper mold 13 are extended to reach a base of the lower mold 12 when assembled, at which time it is fixed by means of a lower packing 45, keeping a spacing 51 in between. There are also upper packings 46 and vent holes 48 on the openable upper portions 16 of the lower mold 12.

Now, the molding process using this mold 11 will be explained.

First, a skin cover 26 made of a surface skin 27 and a wadding 28 is placed over the lower mold 12. The middle mold 14 is then attached and the openable side portions 17 and upper portions 16 are closed such that edges of the skin cover 26 are pinched between the hedge 24 and the upper portions 16, as shown in FIG. 3.

Then, the liquid foam resin is poured in. Here, by controlling the pressure inside the spacing 51 between the lower mold 12 and the upper mold 13, it is possible to control the amount of liquid foam resin which penetrates into the wadding 28. Namely, when the pressure inside the spacing 51 is lowered, it becomes easier for the liquid foam resin to penetrate into the wadding 28 because the foaming gases can easily escape though the lower and upper hinges 15a and 15b, whereas when the pressure inside the spacing 51 is raised, it becomes harder for the liquid foam resin to penetrate into the wadding 28 because the foaming gases cannot easily escape though the lower and upper hinges 15a and 15b. This controlling of the pressure inside the spacing 51 can be accomplished by either changing the volume of the spacing 51 or by providing pressure by means of a controlling pump to the spacing 51.

Also, by means of the vent holes 48, the liquid foam resin can be circulated well enough to reach the region between the openable upper portions 16 and the middle mold 14. Here, it is preferable to provide valves to the vent holes 48 so that the vent holes 48 can be closed after an appropriate time from the pouring of the liquid foam resin.

After the pouring in of the liquid foam resin is completed, the upper mold 13 is assembled over the lower mold 12 and middle mold 14. Here, because of the extended side portions 43, excessive weight is prevented from being exerted onto the lower mold 12.

Finally, after the foaming process of the liquid foam resin is completed, the upper mold 13 is opened and the middle mold 14 is removed, so that a skin covered foamed plastic article composed of the skin cover 26 and the foam resin can be lifted out of the lower mold 12.

As explained, according to the present invention, it is possible to provide a mold for skin covered foamed plastic molding which utilizes a middle mold to be placed between an upper mold and a lower mold, capable of avoiding an excessive amount of pressure to be exerted on the upper portion of the lower mold so that the durability of the lower mold can be improved, and preventing gaseous leakage so that the penetration of the liquid foam resin to be poured on a skin cover becomes controllable.

It is to be noted that the upper mold 13 and the middle mold 14 shown in FIGS. 4(A) and 4(B), respectively, may be replaced by those shown in FIGS. 5(A) and 5(B), respectively, in which the bent 36 of the upper mold is extended all the way to a bottom side and the bottom side 37 is absent in the middle mold 14.

Besides this, many modifications and variations of the above embodiments may be made without departing from the novel and advantageous features of the present invention. Accordingly, all such modifications and variations are intended to be incorporated within the scope of the appended claims.