1. Technical Field
The invention relates to the fields of apparatus and method of forming composite structures and, in particular, to the molding of articles using infrared heat.
2. Description of the Related Art
Composites parts typically comprise filamentary materials such as graphite or FIBERGLAS glass fiber within a thermoplastic or thermoset resin matrix. The type of filamentary material and orientation thereof as well as the type of resin used is dependent upon the design requirements of the article to be manufactured. The typical procedure for making such parts is to layup a multiple number of plies of the preimpregnated filamentary material on the surface of a mold. The layup is vacuum bagged by placing a layer of Polyimide film, Nylon or silicon rubber over the layup and sealing it to the mold about the periphery thereof forming an evacuatable envelope. During the sealing process a tube is installed so that a vacuum can be drawn from the envelope. When the vacuum is in fact drawn from the envelope atmospheric pressure compresses the layup. Higher pressure can be applied by use of an autoclave. Thereafter, the assembly is heated, in the case of thermosets to curing temperatures and when using thermoplastics to the melting point. Upon cooling, a homogeneous part results.
If the forming temperature is relatively low, around 350.degree. F., then aluminum, steel or epoxy composite molds can be used. If the forming temperature is high, such as 700.degree. F. required to melt a thermoplastic resin such as polyetheretherketone (PEEK), then more exotic ceramic or graphite tooling is required. A number of heating techniques can be used. For example, integral heating elements can be cast in a ceramic mold or the whole assembly can be placed in an autoclave and heated therein. The use of an autoclave would also allow an increase in the compaction pressure above atmospheric.
Glass tooling has been used in various manufacturing operations, for example, U.S. Pat. No. 4,360,483 "Apparatus for A Method of Pressing Plastic Sheets" by R. L. Ayres, discloses a method of press stretching and or press polishing of acrylic sheets. In this apparatus flat tempered glass plates are used to accomplish the press stretching or press polishing, the glass sheets being loaded by a conventional press. In U.S. Pat. No. 4,643,785 "Method of Manufacturing a Filter" by R. D. Paynton, a method is disclosed for making a filter for use in combination with a cathode ray tube screen. As part of the process for making the filter, a wire mesh impregnated with a thin layer of a bonding agent is joined to a translucent plastic sub strate. The bonding agent is first deposited on a piece of glass, and thereafter, the mesh is embedded therein. The substrate is then placed onto the mesh. The backside of the glass is illuminated so that any gaps in the bonding agent are exposed. Applicant is unaware of any other applications for glass tooling, and particularly, has not heretofore seen the use of glass tooling for the manufacture of composite parts.
Thus, it is a primary object of the subject invention to provide an apparatus for and method for forming composite parts.
It is another object of the subject invention to provide an apparatus for and method for making composite parts utilizing glass molds.
It is a further object of the subject invention to provide an apparatus for and method for making composite parts utilizing infrared heating techniques.