Plastic molding product having foam with outer skin

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plastic molding including a core which is provided on an outer surface thereof with a foam with an outer skin, and a method for producing the same.

2. Description of the Related Art

For instance, a conventional instrument panel for an automobile is usually made of a core 81 (base or substrate) which is provided, on a part or entirety (not shown) of the outer surface thereof, with a pad comprising a foam 83 with an outer skin, depending on a design, as shown in FIG. 18. FIG. 19 shows an enlarged sectional view taken along the line A--A in FIG. 18.

In an instrument panel made of a core and a foam with an outer skin, provided on a part of the outer surface of the core, a foam assembly 83 comprising a mounting base 84, a foam 86 and an outer skin member 87 is prepared in advance and is mounted to a core 81 at a predetermined position. To mount the foam assembly 83 to the core 81, mounting pins 85 provided on the base 84 of the foam assembly 83 are inserted and bent in mounting holes 82 formed in the core 81. Clips or screws, etc., can be used in place of the mounting pins 82.

However, since the foam assembly 83 is provided with the base 84 which is usually made of a steel plate, the instrument panel is heavy and expensive.

Moreover, since the foam assembly 83 is mounted to the core 81 in a subsequent stage, a gap or clearance tends to occur at a connecting portion 88 between the foam assembly 83 and the core 81, thus leading to a poor or bad appearance of the plastic molding (product). In particular, in an instrument panel made of a core whose outer surface is partly covered by the foam assembly, since the connecting portion 88 between the core 81 and the foam assembly 83 appears on the outer surface of the plastic molding, the gap or clearance is unacceptable from the aesthetic view point. Furthermore, an additional troublesome process to mount the foam assembly to the core is necessary.

In an instrument panel made of a core whose outer surface is entirely covered by the foam assembly, a skin member which is provided on the peripheral edge thereof with a skirt to prevent the surface of the skin from being stained is used. Namely, the skin member is disposed on a die surface of a lower die of a die assembly which is comprised of the lower die and an upper die, so that the skirt is located on a periphery of a cavity, i.e., a parting of the die assembly defined by the lower and upper dies. The core is disposed on the die surface of the upper die. When the upper and lower dies are closed, the skirt is held between the upper and lower dies. In the closed position, a foaming material is introduced and foamed in the cavity. The skirt is finally cut and removed to produce a plastic molding (product).

However, in the producing method mentioned above, the foaming material tends to flow or leak from the periphery of the cavity during foaming, thus resulting in an occurrence of a flash. Moreover, it is necessary to cut and remove the skirt of the skin member, which is stained with flash, and, troublesome. In addition to the foregoing, the foaming material sticking to the outer surface of the cut skirt makes it difficult to reuse the cut skirt, resulting in a waste of the material.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a light plastic molding (product) of a good appearance comprised of a core which is provided on a part of the outer surface thereof with a foam with an outer skin or a light plastic molding (product) of a good appearance having no flash, comprised of a core which is provided on an entire outer surface thereof with a foam with an outer skin, wherein there is no waste of the material of which the skin member is made.

Another object of the present invention is to provide a method for producing such a plastic molding (product).

To achieve the object mentioned above, according to a first aspect of the present invention, there is provided a plastic molding having a core and a skin-provided foam provided on an outer surface of the core, said core being provided with side walls, a foaming material receiving portion defined by the side walls, and through holes provided in the bottom surface of the foaming material receiving portion to extend through the core to connect the foaming material receiving portion to the outside of the core, said skin-provided foam being comprised of a foam which is received in the foaming material receiving portion of the core to be adhered to the bottom surface thereof and enters the through holes of the core to constitute engaging portions with the core, and a skin member which covers the outer surface and side surfaces of the foam and is held at the end portions thereof between the foam and the side walls of the core.

According to another aspect of the present invention, there is provided a method for producing a plastic molding having a core and a skin-provided foam provided on an outer surface of the core, comprising the steps of disposing a skin member whose ends are bent backward to form side portions, on a die surface of a lower die; disposing a core which is provided with side walls, a foaming material receiving portion defined by the side walls, and through holes formed in the bottom surface of the core to connect the foaming material receiving portion to the outside of the core, on a die surface of a upper die of a die assembly, so that the skin member is fitted in the foaming material receiving portion of the core; and pouring and foaming a foaming material in a space between the bottom surface of the foaming material receiving portion and the skin member to form a foam integral with the core and the skin member, wherein the foaming material enters the through holes of the core to form an engaging portion between the foam and the core.

A plastic molding (product) obtained by the present invention is light, since the skin-provided foam consists of a foam and a skin and has no heavy steel base. Moreover, since the foaming material that enters the through holes of the core serves as a rigid connector of the foam to the core, no separation of the foam from the core or the skin member from the foam occurs.

When the foaming material is foamed, the internal pressure in the space between the bottom surface of the foaming material receiving portion of the core and the skin member is increased owing to continuing reaction of the foaming material. Accordingly, the side walls of the skin member are pressed by the expanded foaling material onto the corresponding side walls of the foaming material receiving portion of the core to establish a fluid-tight seal therebetween. However, since there are through holes of the core provided at the end portions of the foaming material receiving portion of the core and located above the ends of the skin member to connect the foaming material receiving portion to the outside of the core, the internal pressure becomes low due to escape of air and generated gas. Consequently, the foaming material flows toward the end portions of the foaming material receiving portion in which the through holes are provided and enters the through holes while pressing the side walls of the skin member outward. As a result, the side walls of the skin member can be more effectively and reliably sealed.

Note that even if the side walls of the skin member are made of uneven or slightly waved surfaces, the side walls of the skin member are pressed onto the corresponding side walls of the foaming material receiving portion of the core by the foaming pressure, i.e., internal pressure within the closed space between the core and the skin member, which is generated and increased by foaming (continuing reaction) of the foaming material, thus resulting in an establishment of the fluid-tight seal therebetween.

Since the through holes formed in the core that constitutes a back of a plastic molding (product) are adapted to discharge the foaming gas (i.e., pressure) as mentioned above, the foaming material can be easily and positively introduced into the through holes, so that no exit of the foaming material occurs between the side walls of the skin member and the side walls of the foaming material receiving portion of the core, thus resulting in a prevention of the foaming material from leaking out onto the outer surface of the skin member, leading to a bad appearance of the plastic molding (product).

Moreover, since the foaming material that has entered the through holes completes its foaming and curing reaction subsequently, the foaming material serves as a rigid connector of the foam to the core. Namely, the skin-provided foam can be firmly secured to the core. Furthermore, since the foaming material is foamed or expanded while pressing the side walls of the skin member against the side walls of the foaming material receiving portion of the core, there is no gap between the core and the skin-provided foam in a plastic molding (product) thus obtained. This improves an aesthetic appearance of the plastic molding (product).

In addition to the foregoing, since the skin member has no skirt to be cut, no additional cutting operation for the skirt is necessary. Consequently, the manufacturing or assembling process can be simplified as a whole.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below in detail with reference to the accompanying drawings, in which;

FIG. 1 is a sectional view of a plastic molding (product) having a foam with an outer skin provided on a part of a surface of a core, according to a first embodiment of the present invention;

FIG. 2 is an enlarged sectional view of a main part of FIG. 1;

FIG. 3 is a sectional view of a plastic molding (product), according to a second embodiment of the present invention;

FIG. 4 is an enlarged sectional view of a main part of a plastic molding (product), according to a third embodiment of the present invention;

FIG. 5 is an enlarged sectional view of a main part of a plastic molding (product), according to a fourth embodiment of the present invention;

FIG. 6 is an enlarged sectional view of a main part of a plastic molding (product), according to a fifth embodiment of the present invention;

FIG. 7 is a sectional view of a die assembly in which a skin member and a core are arranged, for producing a plastic molding (product) shown in FIG. 1;

FIG. 8 is a sectional view of a die assembly in which a foaming material is introduced, for producing a plastic molding (product) shown in FIG. 1;

FIG. 9 is an enlarged sectional view of a main part of FIG. 8;

FIG. 10 is an enlarged sectional view of a die assembly in which a foaming material enters a through hole in a closed state;

FIG. 11 is a sectional view of a die apparatus for producing a plastic molding (product), according to another aspect of the present invention;

FIG. 12 is a sectional view of a die apparatus for producing a plastic molding (product), according to still another aspect of the present invention;

FIG. 13 is a sectional view of a die apparatus for producing a plastic molding (product), according to still another aspect of the present invention;

FIG. 14 is a sectional view of a die assembly for producing a plastic molding (product) shown in FIG. 5;

FIG. 15 is an enlarged sectional view of a main part of FIG. 14 during foaming;

FIG. 16 is a sectional view of a die assembly for producing a plastic molding (product) shown in FIG. 6;

FIG. 17 is an enlarged sectional view of a main part of FIG. 16 during foaming;

FIG. 18 is a perspective view of a known plastic molding (product); and, FIG. 19 is a sectional view taken along the line A--A in FIG. 18.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A plastic molding 10 shown in FIGS. 1 and 2 is used for an instrument panel of an automobile and is comprised of a core 11 which is provided on a part of the outer surface thereof with a foam 21 with an outer skin 27. The core 11 and the skin 27 are also shown in FIG. 7 which will be referred to in the following discussion.

Although the following discussion will be addressed to an instrument panel for an automobile, the present invention is not limited thereto. Namely, a plastic molding to be obtained in the present invention and a method for producing the same can be applied to various products.

The core 11 is made of a self-shape maintaining plastic material, such as a rigid plastic material e.g., acrylonitrile-butadiene-styrene (ABS) resin, polypropylene, polyphenylene oxide or fiber-reinforced plastic, etc. The core 11 is provided with side walls 14 which define a foaming material receiving portion 13, so that a foaming material 23 is introduced and received in the foaming material receiving portion 13. The shape and size of the core 11 are determined in accordance with a design or purpose of usage thereof, etc. In FIGS. 1 and 2, numeral 15 designates the bottom surface of the foaming material receiving portion 13.

The core 11 is provided with through holes 17 extending therethrough to connect the foaming material receiving portion 13 to the outside of the core, at the edges of the bottom surface 15 of the core 11. The through holes 17 can be engaged by engaging projections of the foam 23 which will be discussed hereinafter, to constitute an engaging portion between the core and the foam. Namely, the introduced foaming material flows along the side walls 14 of the core 11 according to expansion and flows out onto the rear side of the core 11 opposite to the bottom surface 15 through the through holes 17 during foaming. The number, size (diameter) and distance of the through holes 17 are determined in accordance with the compound of the foaming material, etc., so that an appropriate quantity of the foaming material 23 can be flown into and discharged from the through holes 17 so as not to produce voids in the foam to be formed. For example, the through holes 17 whose diameter is approximately 1 to 4 mm are spaced at a distance of 50 to 200 mm. The distance can be reduced.

The skin-provided foam (foam assembly) 21 is comprised of the foam 23 and the skin member 27 which surrounds the outer surface and the side surfaces of the foam 23. The skin-provided foam 21 is received in the foaming material receiving portion 13 of the core.

The foam 23 whose shape is substantially identical to the shape of the foaming material receiving portion 13 is provided with the engaging projections 25 which are engaged in the through holes 17 of the core 11. A part of the engaging projections 25 spreads over and is adheres to the rear surface of the core 11. The engaging projections 25 are made of the introduced and foamed material in the cavity defined by and between the bottom surface 15 of the core 11 and the skin member as mentioned above. Upon completion of foaming, the foaming material 23 is adhered to both the bottom surface 15 of the core and the inner surface of the skin member 27 due to the self-adhesiveness thereof. In addition, the foaming material enters the through holes 25 to constitute the engaging projections during foaming, and is adhered to the inner surfaces of the through holes. This ensures that the foam 23 is integrally connected to the core.

The skin member 27 which is turned backward at the opposed ends thereof to form the side walls (side portions) 29 covers the outer surface and side surfaces of the foam 23 and is adhered to the foam 23 due to the self-adhesiveness of the foaming material. The side portions of the skin can be molded at the same when the skin is molded in a predetermined shape. The side walls 29 of the skin member 27 are pressed onto the corresponding side walls 14 of the core 11 by the foaming pressure generated and increased by foaming (continuing reaction) of the foaming material 23 in the space defined between the bottom surface 15 of the core 11 and the skin member 27. Namely, the side walls 29 of the skin member 27 are firmly held between the expanded foam 23 and the side walls 14 of the foaming material receiving portion 13 of the core. Consequently, there is no gap between the foam 23 or the side walls 29 of the skin member 27 and the side walls 14 of the core 11.

The skin member 27 is made of an impermeable material, such as a leather-like plastic sheet or a fabric sheet whose back surface is coated with a plastic or banded with a plastic film, etc. If the skin member 27 is made of a leather-like plastic sheet, a certain kind of grain pattern 22 is usually provided on the outer surface of the skin member 27 to exhibit a leather-like finish as if it were an animal skin. In this case, however, it is preferable that the surface portions of the skin member that come into contact with the side walls 14 of the core 11 are smooth surfaces 24 without such a grain pattern, so that a close contact can be established between the smooth surfaces 24 of the skin member 27 and the side walls 14 of the core 11 without a gap therebetween, thus resulting in an improved aesthetic appearance of the plastic molding (product).

The plastic molding (product) 10 thus obtained is light owing to an absence of the heavy base unlike the prior art in which the foam assembly is comprised of a base, a foam and a skin member, as mentioned above.

FIG. 3 shows another example of a plastic molding (product) 100.

The plastic molding (product) 100 which is applied to an instrument panel is comprised of the core 110 whose outer surface is entirely covered by the skin-provided foam 210 (the foam 230 with the skin 270). The core 110 is turned toward the skin member 270 at the opposed ends thereof to form side walls 140 which define the foaming material receiving portion 130. There are through holes 170 that are provided in the core 110 at the edges thereof to extend through the core thereby to connect the foaming material receiving portion 130 to the outside of the core 110. In FIG. 3, numeral 230 designates the foam, 250 the engaging portion, and 290 the side walls of the skin member, respectively.

It is possible to provide recessed grooves 140a on the inner surfaces of the side walls 140 of the core 110 to extend along a part or entirety of the periphery of the foaming material receiving portion 130, as shown in FIG. 4. The recessed grooves 140a ensures that if the foaming material 230 penetrates between the side walls 290 of the skin member and the side walls 140 of the foaming material receiving portion because of incomplete seal therebetween, the penetrated foaming material is received foamed in the recessed grooves 140a to seal the same. Moreover, the foaming material thus foamed in the recessed grooves 140a forms the engaging projections 260 to integrally connect the core and the foam.

The shape of the side walls 290 of the skin member 270 and the side walls of the foaming material receiving portion of the core can be modified to enhance the seal effect, for example as shown in FIGS. 5 and 6.

FIG. 5 shows an enlarged sectional view of a main part of a modified plastic molding. The plastic molding 101 shown in FIG. 5 is provided with generally L-shaped bent portions 291c in cross section at the side wall 291, each consisting of a sealing flat surface portion 291a that extends inward from the side wall 291 of the skin member 271 and a seal tongue 291b that extends toward the bottom surface 151 of the foaming material receiving portion 131 from the front end of the sealing flat surface portion 291a. The latter abuts against the front end 141a of the side wall 141 of the core 111. The seal tongues 291b are in surface contact with the inner surfaces of the side walls 141 of the core 111. In FIG. 5, numerals 171, 211, 221, 231, and 251 designate the through hole, the skin-provided foam, the grain pattern, the foam, and the engaging portion, respectively.

In a modified example shown is FIG. 6, the plastic molding 102 is provided with outwardly projecting flanges (only one is shown) 292a provided at the front ends of the side walls 292 of the skin member 272, and inwardly projecting flanges (only one is shown) 112a provided at the front ends of the side walls 142 of the foaming material receiving portion 132 of the core 112. The front ends 142b of the inwardly projecting flanges 142 of the core 112 abut against the side surfaces 292b of the associated side walls 292b of the skin member 272. The inner surfaces of the inwardly projecting flanges 142a are brought into close surface contact with the corresponding outer surfaces of the outwardly projecting flanges 292a of the skin member 272. In FIG. 6, numerals 172, 212, 232, and 252 designate the through hole, the skin-provided foam, the foam, and the engaging portion, respectively.

For the side walls of the skin member and the foaming material receiving portion of the core, the arrangements shown in FIGS. 5 and 6 can be used in combination.

The following discussion will be directed to a method for producing a plastic molding (product) as mentioned above.

First, the plastic molding (product) 10 shown in FIGS. 1 and 2 is produced as follows.

With reference to FIG. 7, the core 11 having the foaming material receiving portion 13 and the through holes 17 at the ends of the bottom 15 thereof, and the skin member 27 having the side walls 29 bent backward at the opposed ends thereof are disposed in the die assembly 31 having the lower die 33 and the upper die 39.

The skin member 27 is located on the die surface 35 of the lower die 33 with the back surface thereof facing the skin member supporting surface 37 of the die surface 35. The skin member supporting surface 37 is recessed with respect to the remaining portion of the die surface 35 to form stepped portions 38, so that the skin member 27 can be correctly positioned on the skin member supporting surface 37.

The core 11 is disposed on the die surface 40 of the upper die 39 with the foaming material receiving portion 13 thereof facing the skin member. The core 11 can be correctly positioned and immovably held on the die surface 40 by holding means such as clips (not shown) or the like attached on the back of the core 11 or on the surface of the upper die 39, that are engaged in the corresponding clip inserting holes (not shown) of the die surface 40 or the core 11. The side walls 29 of the skin member 27 are fitted in the foaming material receiving portion 13 of the core 11 when the die assembly 31 is closed.

The foaming material P, comprising reactive ingredients such as polyurethane composition is poured in the skin member 27 and thereafter, the upper die 39 and the lower die 33 are closed, as shown in FIG. 9. Consequently, the skin member 27 covers the opening end of the foaming material receiving portion 13 of the core 11. In this state, the side walls 29 of the skin member 27 come into contact with or are slightly spaced from the associated side walls 14 of the foaming material receiving portion 13 of the core 11, owing to the inward inclination or falling of the upper ends of the side walls 29 due to the dead weight thereof, as can be seen in FIG. 9. The through holes 17 of the core 11 are located above the side walls 29 of the skin member 27.

Thereafter, the foaming material P is foamed, so that the space between the bottom surface 15 of the foaming material receiving portion 13 and the skin member 27 is filled with the foaming material P thus foamed. During the foaming of the foaming material P, the latter is expanded toward the opposed ends of the bottom surface 15 of the foaming material receiving portion 13 at which the through holes 17 are provided. Consequently, when the expanded foaming material P reaches the side walls 29 of the skin member 27, as indicated at a phantom line in FIG. 9, the side walls 29 are pressed onto the side walls 14 of the core 11 by the expanded foaming material P. Thus, a seal can be established between the side walls 29 of the skin member 27 and the side walls 14 of the core 11, as shown in FIG. 10. If the portions of the side walls 29 that are to come into press contact with the side walls 14 of the core 11 are smooth flat surfaces 24 having no grain pattern, as mentioned above, there is no gap between the side walls 14 and the side walls 29, thus resulting in a closer surface contact therebetween and a more reliable seal.

Even if the side walls 29 fail to come into close contact with the side walls 14 of the core 11 due to possible uneven or waved side wall surfaces 29 depending on the material or the shape of the skin member 27 or the temperature of the molding die assembly, etc., the side walls 29 of the skin member 27 are pressed against the side wall surfaces 14 of the foaming material receiving portion 13 of the core 11 by the foaming pressure generated and increased by foaming of the expanded foaming material P. Consequently, a reliable seal can be always obtained.

The foaming material P continues expanding along the side walls 29 or the skin member 27 and enters the through holes 17 and reaches the outer surface of the core 11. The number and the size of the through holes 17 are determined in accordance with flow resistance (viscosity) increased by the reaction of the foaming material, etc., so that an appropriate amount of the foaming material P is discharged from the through holes 17 onto the outer surface of the core 11 so as not to produce voids in the foam 23, as mentioned above. When the foaming material P completes its reaction, the same is adhered to the skin member 27 the core 11 due to the self-adhesiveness thereof thereby to produce an integral plastic molding. The foaming material P in the through holes 17 serves as