Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Composite article making
Reexamination Certificate
1998-12-04
2001-01-16
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Composite article making
C264S046400, C264S513000, C264S514000, C264S173150, C264S515000
Reexamination Certificate
active
06174470
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a method of manufacturing a blow-molded article having an integral airbag door. More specifically, the present invention is directed to manufacturing an automotive instrument panel having an integral airbag door by simultaneously extruding the one or parison layers and blow-molding the layers to form the panel.
2. Description of the Related Arts
Modern automotive interiors utilize instrument panels that provide a soft touch feel. These instrument panels are usually formed by laminating a flexible skin to a rigid substrate. Many of these processes also included placing a foam material between the skin and substrate to provide a soft-touch feel. These instrument panels have been formed by injection molding one or more of the components of the instrument panel. While injection molding provides design flexibility, it generally requires expensive equipment and tools and does not form an article that has a hollow core.
Another trend among automobile interiors are instrument panels that have a seamless covering over an airbag door. The decorative layer of the instrument panel is used to conceal the airbag door. These instrument panels and made of the usual injection molded construction. A opening path is formed in the substrate, cover and foam to enable the door to open when the airbag is initiated. This construction provides a decorative, seamless appearance, but requires complex and expensive assembly steps for the various components of the instrument panel and airbag door.
It is also known to manufacture hollow articles by blow-molding. These articles utilize a parison extruded between two molds. The parison is inflated to cause the parison to conform to the mold walls. Among the articles that may be made using this process are instrument panels for automobiles. Japanese Patent Application Number 04-283977, filed Sep. 29, 1992, teaches molding a three-layer instrument panel using a skin layer, a foaming body intermediate layer and a base member layer. The skin layer is composed of an olefin thermoplastic elastomer composition. The intermediate layer is composed of a propylene polymer foaming body having a melt tension at 230° C. of 2-20 g. The base member layer is composed of a propylene polymer containing 10-50% by weight of a granular filler or a fibrous filler. The three layer structure is integrally molded into an instrument panel by a multi-layer blow-molding apparatus. The method and construction taught by this application is limited to a simple instrument panel structure that does not includes an integral airbag door or reinforcement supports strengthening the instrument panel.
U.S. Pat. No. 5,328,651 ('651), teaches a method of blow-molding a covering and foam backing for an automotive instrument panel. The skin and foaming material are co-extruded in a blow-molding apparatus and formed into the shaped to conform to an instrument panel. The skin and foam are then bonded to a rigid substrate that was conventionally molded. The process taught by the '651 patent is limited to forming the skin and an foam layers of the instrument panel. The underlying rigid supporting substrate is not formed by blow-molding and the instrument panel is not integrally formed.
It is desirable to form an instrument panel that utilizes blow-molding to form the outer decorative skin layer, intermediate foam layer and underlying substrate layer in a single operation. It is also desirable that the molding operation simultaneously form a concealed door within the instrument panel. The door maybe used to cover an airbag. It is also desirable that the molding operation form the instrument panel to have hollow or channel sections. The hollow or channel sections provide stiffening and rigidity to the instrument panel and allow for air or structural members to pass through the instrument panel.
These and other disadvantages are overcome by the present invention.
SUMMARY
The present invention is directed to a method for forming an automotive instrument panel having a concealed door comprising a series of steps. A plastic parison is extruded to form the substrate layer of the instrument panel. The parison has first and second walls. The parison is placed within a mold and the first wall is contacted with the second wall to form a hinge. The area of contact forms a bond between the first and second walls. A different portion of the first and second walls are contacted to form an opening path. The opening path intersects the hinge. The opening path usually has a thickness much less than the thickness of the first and second walls to form an easily fracturable area. The door swings on the hinge to open. A elongated section of material on the second wall, enables the second wall to wrap along the hinge when the door is opened.
The invention enables the integral molding of the decorative cover, foam and substrate layers using existing co-extrusion equipment. The various layers bond and fuse when the article is molded. The instrument panel may also be formed with channels that extend transversely. These channels are formed during the blow-molding process and provide areas that may be utilized to transfer air or for structural members that reinforce the instrument panel or the vehicle to which it is secured.
When the instrument panel is installed in a vehicle, an airbag is positioned behind the door. The airbag is usually secured to the second wall of the instrument panel. The airbag has sufficient force to fracture the opening path and open the door when the airbag is initiated. The opening path may be formed during the molding process or optionally, the path may be further scored with laser, heat or vibration to cause it to weaken sufficiently to open during inflation of the airbag.
The airbag door and the instrument panel is reinforced by joining the first and second walls to form box sections. These sections may include the hollow channels for air of other members. The box sections are formed when the pliable plastic walls are contacted with each other. The walls fuse to form an integral wall section.
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Heath Gerald Arthur
Helms Jeffrey Hampton
Myers Christopher Alan
Plymale Bradley Richard
Stancu Sorin
Ford Global Technologies Inc.
Jones Kenneth M.
Porcari Damian
Silbaugh Jan H.
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