Patent ID: 6083339
Filing Date: 2000-07-04
Classification: B29C,B29K,B29L,C08K,Y10T

Abstract:
A process for producing an oval concavo-convex bowl shaped item comprising acrylic plastics with a filler of alumina trihydrate of 20 to 85 percent by weight and including colorants and visually distinguishable particles therein, wherein the process includes(a) producing an oval outline shaped rigid flat sheet blank comprising acrylic plastics with a filler of alumina trihydrate of 20 to 85 percent by weight and including colorants and visually distinguishable particles therein,(b) heating said blank to flexible softness and uniform temperature;(c) indexing the heated blank relative to an oval bowl-shaped tool portion of a compression molding tool;(d) reducing tension and shear loads on the heated blank by leaving peripheral side edges of the heated blank unrestrained so as to be free to be moved inward when force is applied by the compression molding tool;(e) applying force with said compression molding tool to said heated blank and forcing said heated blank toward the bowl-shaped tool portion of said compression molding tool sufficiently to force the heated blank into a concavo-convex bowl shaped item having a top oval outline;(f) cooling the concavo-convex bowl shaped item to a greater stiffness;(g) trimming a top edge of the bowl shaped item to a condition of greater evenness;(h) sanding and polishing at least the concave interior surface of the concavo-convex bowl shaped item.