Process for blow molding containers utilizing double pinch

Abstract

Abstract CONTANERS ARE MADE FROM A CONTINUOUS ORIENTED CRYSTALLINE MONO-A-OLEFIN TUBING. ORIENTATION OF THE TUBING IS EFFECTED BY HEATING THE CRYSTALLINE TUBING IN AN OVEN TO A FEW DEGREES BELOW ITS CRYSTALLINE MELTING POINT AND THEN STRETCHING OR ORIENTING THE TUBING IN AN AXIAL DIRECTION. A FIRST MOLD IS CLOSED ABOUT A LENGTH OF TUBING AND INTERNAL PRESSURE IS APPLIED TO EXPAND THE TUBING WITHIN THE MOLD TO FORM A CONTAINER. THE MOLD IS THEN MOVED AWAY FROM THE OVEN AT A RATE WHICH IS FASTER THAN THE RATE THAT THE TUBING IS EMERGING FROM THE OVEN THEREBY STRETCHING OR ORIENTING A LENGTH OF THE TUBING. A SECOND MOLD THEN CLOSES ON THE NEWLY ORIENTED LENGTH OF TUBING AND PROCEEDS IN THE SAME MANNER AS THE FIRST MOLD WHICH OPENS AND DISCHARGES ITS CONTAINER AFTER THE SECOND MOLD CLOSES. A DOUBLE PINCH IS UTILIZED AT THE REAR OF THE MOLD TO PREVENT "BLOW-BACK" OF AIR PRESSURE PAST THE FIRST PINCH INTO THE TUBING IN THE OVEN AND IS ALSO UTILIZED TO PREVENT PULLING MATERIAL AWAY FROM THE FIRST PINCH AREA DUE TO THE MAGNITUDE OF FORCE REQUIRED TO ORIENT THE TUBING.

Inventors

• 👤 R Macduff

Bibliographic Details