Abstract: Method in which an expandable internal shoulder forming member assembly to be used for forming a headpiece onto a preformed thin-walled plastic or laminate tube or bag provides a internal shoulder forming member upon which the loose fitting preformed thin-walled tube can be loaded. After tube loading, the internal shoulder forming member is inserted into a female forming member. Toward the end of the internal shoulder forming member's insertion stroke, a internal neck forming member which is mounted for axially movement within the head end of the internal shoulder forming member contacts the female forming member and then partially retracts into the head end of the internal shoulder forming member as the internal shoulder forming member continues to advance to the end of its insertion stroke.

Abstract: An expandable poincon assembly to be used for forming a headpiece onto a preformed thin-walled plastic or laminate tube or bag provides a poincon upon which the loose fitting preformed thin-walled tube can be loaded. After tube loading, the poincon is inserted into a female forming member. Toward the end of the poincon's insertion stroke, a soupape which is mounted for axially movement within the head end of the poincon contacts the female forming member and then partially retracts into the head end of the poincon as the poincon continues to advance to the end of its insertion stroke. A conically-shaped washer mounted on the bottom end of the soupape is peripherally expanded by the continued advancement of the poincon after the top end of the soupape has contacted the female forming member.