US 3,956,447 AGranted

Method of making deep drawn, laminated articles

AssigneeThe United States of America as represented by the Secretary of the Army

InventorsMaurice R. Denommee, Jack F. Furrer, Lawrence R. McManus, Philip E. Durand

Life of this patent

Estimating the term…

Loading patent…

Abstract

A method of making a deep drawn, laminated, non-metallic article having h ballistic resistance and having a smooth edge which comprises, preparing a preform comprising a plurality of superimposed patterns of aromatic polyamide fabric impregnated with a thermoplastic or thermosetting resin, then either (a) trimming the preform to form a peripheral edge thereon so as to allow for application of additional resin in a suitable form to the peripheral edge during the final molding of the preform, applying the additional resin to the peripheral edge of the trimmed preform, and finish molding the article accompanied by flow of the additional resin about the peripheral edge to produce a smooth edge on the final molded article, or (b) applying an epoxy resin film on the outer surface of the preform, or on the superimposed patterns prior to making the preform, around the periphery of the preform or superimposed patterns and overlapping the line around the periphery of the preform on which cutoff occurs in the finish molding step, and finish molding the article, the finish molding being accompanied by cutoff and flow of the epoxy resin over the edge produced by cutoff to produce a smooth edge on the final molded article.

Claims12

Dependent claims

Method of making a deep drawn, laminated article having a smooth edge, said article formed of a plurality of laminae of woven fabric composed of aromatic polyamide yarns impregnated with sufficient resin to cause said laminae to adhere together, said aromatic polyamide yarns having a tendency to form a stubbled edge on said article when trimmed to form the peripheral edge thereof, comprising the steps of:

a. impregnating a woven fabric composed of aromatic polyamide yarns with a resin mixture comprising a first thermoplastic or thermosetting resin and a volatile solvent,
b. removing said volatile solvent from the impregnated fabric by evaporation to form a resin-impregnated and solvent-free fabric,
c. preparing a plurality of preform patterns from said resin-impregnated and solvent-free fabric, said patterns being cut in a generally star shape,
d. superimposing said plurality of preform patterns on each other, said patterns being overlapped sufficiently to provide an effective number of thickness of said resin-impregnated and solvent-free fabric greater than the actual number of patterns in the final molded article over a large portion of said article,
e. tacking said plurality of preform patterns together in overlapping stage,
f. placing the tacked superimposed patterns on the male element of a deep draw compression mold,
g. deep draw molding said tacked superimposed patterns with the assistance of the female element of said mold and low heat and pressure to produce a deep drawn preform having a preliminary edge,
h. removing said deep drawn preform from said mold,
i. applying a second resin along that portion of said preform which is to comprise the peripheral edge of the preform, said second resin being thermoplastic or thermosetting and in a sufficient quantity and having rheological characteristics at the temperature and pressure at which finish molding is carried out which cause said second resin to flow over and about said peripheral edge of said preform, and
j. finish molding said deep drawn preform to produce said article with a smooth finish peripheral edge formed thereon by said second resin.

7 more elements

Method of making a deep drawn, laminated, ballistic-resistant helmet having a smooth edge, said helmet formed of a plurality of laminae of woven fabric composed of aromatic polyamide yarns impregnated with sufficient resin to cause said laminae to adhere together, said aromatic polyamide yarns having a tendency to form a stubbled edge on said helmet in the final molding step employing a deep drawing mold, comprising the steps of:

a. impregnating a woven fabric composed of aromatic polyamide yarns with a resin mixture comprising a first thermoplastic or thermosetting resin and a volatile solvent,
b. removing said volatile solvent from the impregnated fabric by evaporation to form a resin-impregnated and solvent-free fabric,
c. preparing a plurality of preform patterns from said resin-impregnated and solvent-free fabric, said patterns being cut in a generally star shape,
d. superimposing said plurality of preform patterns on each other, said patterns being overlapped sufficiently to provide and effective number of thicknesses of said resin-impregnated and solvent-free fabric greater than the actual number of patterns in the final molded helmet over a large portion of said helmet,
e. superimposing on said plurality of preform patterns at least one additional lamina of said resin-impregnated and solvent-free fabric shaped so as to cover that portion of said final molded helmet in which no overlapping of said patterns occurs to produce a helmet of constant thickness,
f. tacking said plurality of preform patterns togeter in overlapping state and said additional lamina of said resin-impregnated and solvent-free fabric superimposed on said plurality of preform patterns,
g. placing the tacked superimposed patterns and said additional lamina on the male element of a deep draw compression mold,
h. deep draw molding said tacked superimposed patterns and said additional lamina with the assistance of the female element of said mold and low heat and pressure to produce a deep drawn preform having a peripheral edge,
i. removing said deep drawn preform from said mold,
j. applying a second resin along the peripheral edge, said second resin being thermoplastic or thermosetting and in a sufficient quantity and having rheological characteristics at the temperature and pressure at which finish molding is carried out which cause said second resin to flow over and about said peripheral edge of said preform, and
k. finish molding said deep drawn preform to produce said helmet with a smooth finish peripheral edge formed thereon by said second resin.

8 more elements

Dependencies are inferred from the claim text.