Apparatus for flanging tubular polymer articles

Apparatus for flanging tubular articles of a thermoplastic polymer which has been drawn and heat-set to an elevated temperature comprising:

• (a) a heating die shaped to receive an end of one of the tubular articles and to restrain said end from shrinkage, said heating die being a heated body with an annular recess dimensioned to receive the end of the tubular article,
• (b) means for maintaining the heating die at a temperature at which the thermoplastic polymer is softened, said softening temperature being above the glass transition temperature of the polymer but below the elevated temperature to which it has been heat-set;
• (c) means for applying an end of one of the tubular articles to the heating die so that said end is softened while restrained from residual shrinkage by the heating die;
• (d) a forming die shaped to form an outward flange on said end of the tubular article, said forming die being a heated body with a boss running into an outward flange for forming the outwardly directed flange on the tubular article,
• (e) means for holding the forming die at a forming temperature below the softening temperature;
• (f) means for transferring the tubular article from the heating die to the forming die;
• (g) means for forcing the forming die and the heat-softened end of the tubular article together to form said outward flange;
• (h) means for cooling the flanged end of the tubular article while said flange is being set, said cooling means being located externally of the tubular article.