Patent Application
20070057401
1. Field of the Invention
The present invention is related to multi-component automobile interior panels made by injection molding.
2. Background Art
Multishot molding is a type of injection molding process in which a plastic part having several different colors or several different resins is formed. For example, in two shot molding a plastic part is formed from two different materials. This process is easily automated and able to produce success parts such as buttons and gear wheels with a firm core yet a soft feel. Although multi-material molding is a relatively new molding technology in the United States, it has been popular in Europe for a number of years. Multishot molding is particularly useful for hard and soft combinations of resins, multicolored components, housing or connectors with seals or gaskets, grips and tactile applications, back-lit graphics, weatherproofing, and vibration reduction. Accordingly, multishot molding is potentially useful for fabrication of automobile interior components.
In the typical two shot method, a first resin is injected into the molding apparatus to form a pre-molded part. Next, a second unit injects a second resin onto the premolded part. Typically, the two shot process is automated to form articles having different combinations of resins or colors. Although the two shot process works well, fabrication of multicomponent parts such as automobile trim panels often include a number of discrete steps that add to the overall cost of a part.
Accordingly, there is a need for multishot molding processes in which fabrication steps are reduced or combined together.
The present invention overcomes one or more problems of the prior art by providing in at least one embodiment a method of making automobile interior panels. The method of this embodiment comprises positioning a first insert in a first mold cavity. The first mold cavity is formed by the appropriate relative positioning of a first mold section and a second mold section. Advantageously, the first insert is trimmed by a first lifter to form a trimmed first insert. The first mold section, the second mold section, the first lifter, and the trimmed first insert are positioned to form a second mold cavity. A first resin is then introduced into the second mold cavity such that this first resin bonds to the trimmed first insert. In variations of this embodiment, additional lifters and/or mold sections are used to define mold cavities and paths for introducing additional resins to form more complex interior panels.
In another embodiment of the present invention, an automobile interior panel made by the methods set forth above for the first embodiment is provided. The automobile panel of this embodiment is characterized in that at least one applique is attached to a substrate with an over-molded bond.
The following detailed description of the embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present invention, which constitute the best modes of practicing the invention presently known to the inventors. The figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to variously employ the present invention.
Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: percent, “parts of”, and ratio values are by weight; the term “polymer” includes “oligomer”, “copolymer”, “terpolymer”, and the like; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.
As used herein, “over-molding” refers to the injection molding process in which a first material is molded onto a second material. When properly performed, the first material forms a strong bond with the second material without the use of primers or adhesives.
As used herein, “over-molded bond” refers to the bond between a first material and a second material when the first material is over-molded onto the second material. It should be appreciated that the precise nature of the over-molded bond will depend on the type of materials bonded together. For example, if two plastics are bonded together the over-molded bond is typically cohesive in nature. If a resin is bonded to a somewhat porous material like clothe, the resin tends to fill openings in the clothe to form a type of interlocking bond.
With reference to
With reference to
Advantageously, first insert 60 is trimmed first lifter 56 to form trimmed first insert 70, typically with back edge 68. This trimming of first insert 56 is accomplished by moving first lifter 56 along direction d1. Moreover, it should be appreciated that this trimming will shape first insert 60 into the general shape defined by edge 16. Next, first mold section 52, second mold section 54, first lifter 56, and trimmed first insert 70 are positioned to form second mold cavity 80. Again, a press is usually used for positioning first mold section 52 and second mold section 54. During this positioning, first lifter 56 is then moved along direction d2 to an intermediate position while first mold section is moved in a relative sense along direction d3. Positioning of first mold section 52 and second mold section 54 is usually accomplished with a press. First resin 90 is then introduced into second mold cavity 80 such that this first resin bonds to first trimmed insert 70. Typically, first resin 90 is introduced at an elevated temperature such that first resin 90 is in a liquid state (i.e., first resin 90 is melted). In the finished part, first resin 90 corresponds to substrate 22. Upon cooling first resin 90 is bonded to trimmed first insert 70 with an over-molded bond as defined above. Typically, first resin 90 is injected into second mold cavity 80 at a temperature from about 350° F. to about 440° F. and a pressure from about 700 psi to about 2100 psi. It should be appreciated that these temperature and pressure ranges will vary depending on the materials used. After the press closes the mold, the first resin is pushed behind first insert 70 filling out second mold cavity 80.
With reference to
In the finished product, first insert 60 corresponds to applique 20 described in
First resin 90, second resin 94, and third resin 106 each independently comprise a thermoplastic resin. Examples of useful thermoplastic resins include thermoplastic polyurethanes, thermoplastic olefins, polyvinyl chloride, polypropylene, and combinations thereof. More specific examples from which first resin 90, second resin 94, and third resin 106 may be formed are homopolymers and copolymers of polyethylene, homopolymers and copolymers of polypropylene, thermoplastic olefins, thermoplastic urethanes, polycarbonate, acrylonitrile butadiene styrene, mixed acrylonitrile butadiene styrene and polycarbonate, and combinations thereof.
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.
