Process and apparatus for forming glass-reinforced plastic pipe

Claim 2

IN A PROCESS FOR FORMING A GLASS ROVING-RESIN PIPE, THE STEPS COMPRISING APPLYING A SOLIDIFIABLE COATING OF LOW MELTING POINT TO A PIPE FORM HAVING A CENTER SECTION OF MAGNETIC SUSCEPTIBILITY, ALLOWING SAID COATING TO SOLIDIFY, APPLYING A COATING OF CURABLE RESIN HAVING A HIGHER MELTING POINT THAN THAT OF SAID SOLIDIFIABLE COATING IN THE CURED STATE TO SAID LATTER COATING, CURING THE RESIN COATING, APPLYING HELICAL WRAPS OF GLASS ROVING UNDER TENSION ALONG THE LENGTH OF SAID PIPE FORM OVER SAID CURED RESIN COATING, SAID TENSION BEING OF SUCH MAGNITUDE AS TO CAUSE DEFORMATION OF SAID PIPE FORM, SAID DEFORMATION INCREASING AS THE PIPE FORM CENTER IS APPROACHED, APPLYING ADDITIONAL UNCURED RESIN TO SAID HELICAL WRAPS OF GLAS ROVING SO AS TO IMPREGNATE THE SAME, EXERTING INCREASING MAGNETIC FORCES OF ATTRACTION ON THE CENTER SECTION OF SAID PIPE FORM IN DIRECT OPPOSITION TO THE DEFORMATION FORCES EXERTED ON SAID PIPE FORM BY SAID ROVING WRAPS AS THE CENTER THEREOF IS WRAPPED BY SAID HELICAL WRAPS, AND DECREASING SAID MAGNETIC ATTRACTIVE FORCES AS SIDE PIPE FORM ENDS ARE WRAPPED BY SAID HELICAL WRAPS OF IMPREGNATED GLASS ROVING, CURING THE ADDITIONAL RESIN IMPREGNATING SAID ROVING AFTER PIPE OF DESIFED THICKNESS HAS BEEN FORMED APPLYING HEAT TO THE PIPE FORM INTERIOR TO MELT SAID COATING OF LOW MELTING POINT, AND REMOVING THE PIPE FROM SAID PIPE FORM.

Claim 3

IN AN APPARATUS FOR FOMING A SUBSTANTIALLY STRAIGHT, ELONGATE TUBULAR MEMBER ON A HOLLOW MANREL; SAID TUBULAR MEMBER BEING FORMED AT LEAST IN PART FROM LONGITUDINALLY DISPOSED ROVING, AND HELICAL WRAPPINGS WHICH ARE WOUND ABOUT SAID MANDREL UNDER SUCH TENSION ALONG THE LENGTH OF SAID MANDREL AS TO BEND SAID MANDREL, THE COMBINATION COMPRISING A ROTATABLE MANDREL FABRICATED OF MATERIAL WHICH EXPANDS UPON HEATING, MOUNTINGS FOR SAID MANDREL ENGAGING OPPOSED END PORTIONS THEREOF, MEANS FOR APPLYING A HELICAL WRAP TO SAID MANDREL ALONG THE LENGTH THEREOF UNDER SUCH TENSION AS TO PULL THE ENGAGED PORTIONS OF THE MANDREL OUT OF LONGITUDINAL ALIGNMENT WITH THE REMAINDER OF THE MANDREL TOWARD THE APPLYING MEANS, NON-ALIGNMENT OF THE ENGAGED PORTION OF THE MANDREL BEING AT A MXIMUM AT SAID MANDREL CENTER AND AT A MINIMUM AT OPPOSED MANDREL END LIMITS, A CENTRAL PORTION OF SAID MANDREL BEING MAGNETICALLY ATTRACTED, ELECTROMAGNETIC MEANS EXERTING ATTRACTIVE FORCES ON SAID MAGNETICALLY ATTRACTED PORTION IN OPPOSITION TO SAID FORCES EXERTED BY THE WRAP-APPLYING MEANS WHEREBY SAID MANDREL MAY REMAIN SUBSTANTIALLY STRAIGHT IN THE NORMAL COURSE OF APPARATUS OPERATION, MEANS FOR ENERGIZING SAID ELECTROMAGNETIC MEANS WHEREBY THE SAME WILLEXERT AN ATTRACTIVE FORCE ON SAID MAGNETICALLY ATTRACTED MEANS IN ACCORDANCE WITH THE POINT OF ENAGEMENT OF SAID WRAP ON SAID MANDREL, ANCHOR MEANS ABUTTING OPPOSED END PORTIONS OF SAID HOLLOW MANDREL FOR ENGAGING OPPOSED END PORTIONS OF LONGITUDINAL ROVING STRANDS, MEANS FOR APPLYING A HEAT HARDENABLE MATERIAL TO ROVING DISPOSED ON SAID MANDREL WHEREBY SAID ROVING BECOMES IMPREGNATED WITH SAID HEAT HARDENABLE MATERIAL, AND MEANS FOR HEATING THE INTERIOR OF SAID MANDREL WHEREBY SAID MANDREL LONGITUDINALLY EXPANDS FORCING SAID ANCHOR MEANS APART THEREBY INCREASING THE TENSION IN SAID LONGITUDINAL ROVING STRANDS ANCHORED TO SAID ANCHOR MEANS, THE HEAT APPLIED TO THE INTERIOR OF SAID HOLLOW MANDREL BY THE HEATING MEANS SIMULTANEOUSLY CURING SAID HEAT HARDENABLE MATERIAL AS SAID LONGITUDINAL STRANDS ARE UNDER TENSION.

Claim 4

IN AN APPARATUS FOR FOMING A SUBSTANTIALLY STRAIGHT, ELONGATE TUBULAR MEMBER ON A HOLLOW MANREL; SAID TUBULAR MEMBER BEING FORMED AT LEAST IN PART FROM LONGITUDINALLY DISPOSED ROVING, AND HELICAL WRAPPINGS WHICH ARE WOUND ABOUT SAID MANDREL UNDER SUCH TENSION ALONG THE LENGTH OF SAID MANDREL AS TO BEND SAID MANDREL, THE COMBINATION COMPRISING A ROTATABLE MANDREL FABRICATED OF MATERIAL WHICH EXPANDS UPON HEATING, MOUNTINGS FOR SAID MANDREL ENGAGING OPPOSED END PORTIONS THEREOF, MEANS FOR APPLYING A HELICAL WRAP TO SAID MANDREL ALONG THE LENGTH THEREOF UNDER SUCH TENSION AS TO PULL THE ENGAGED PORTIONS OF THE MANDREL OUT OF LONGITUDINAL ALIGNMENT WITH THE REMAINDER OF THE MANDREL TOWARD THE APPLYING MEANS, NON-ALIGNMENT OF THE ENGAGED PORTION OF THE MANDREL BEING AT A MXIMUM AT SAID MANDREL CENTER AND AT A MINIMUM AT OPPOSED MANDREL END LIMITS, A CENTRAL PORTION OF SAID MANDREL BEING MAGNETICALLY ATTRACTED, ELECTROMAGNETIC MEANS EXERTING ATTRACTIVE FORCES ON SAID MAGNETICALLY ATTRACTED PORTION IN OPPOSITION TO SAID FORCES EXERTED BY THE WRAP-APPLYING MEANS WHEREBY SAID MANDREL MAY REMAIN SUBSTANTIALLY STRAIGHT IN THE NORMAL COURSE OF APPARATUS OPERATION, MEANS FOR ENERGIZING SAID ELECTROMAGNETIC MEANS WHEREBY THE SAME WILLEXERT AN ATTRACTIVE FORCE ON SAID MAGNETICALLY ATTRACTED MEANS IN ACCORDANCE WITH THE POINT OF ENAGEMENT OF SAID WRAP ON SAID MANDREL, ANCHOR MEANS ABUTTING OPPOSED END PORTIONS OF SAID HOLLOW MANDREL FOR ENGAGING OPPOSED END PORTIONS OF LONGITUDINAL ROVING STRANDS, MEANS FOR APPLYING A HEAT HARDENABLE MATERIAL TO ROVING DISPOSED ON SAID MANDREL WHEREBY SAID ROVING BECOMES IMPREGNATED WITH SAID HEAT HARDENABLE MATERIAL, AND MEANS FOR HEATING THE INTERIOR OF SAID MANDREL WHEREBY SAID MANDREL LONGITUDINALLY EXPANDS FORCING SAID ANCHOR MEANS APART THEREBY INCREASING THE TENSION IN SAID LONGITUDINAL ROVING STRANDS ANCHORED TO SAID ANCHOR MEANS, THE HEAT APPLIED TO THE INTERIOR OF SAID HOLLOW MANDREL BY THE HEATING MEANS SIMULTANEOUSLY CURING SAID HEAT HARDENABLE MATERIAL AS SAID LONGITUDINAL STRANDS ARE UNDER TENSION.