Method of ultrasonically cutting and sealing thermoplastic workpieces particularly a filter

摘要

A two step process for ultrasonically welding together first and second thermoplastic pieces and welding a membrane between these two pieces. The first piece comprises an annular bead, the second piece comprises an annular energy director. The method comprises first ultrasonically cutting and sealing the membrane to the first piece using an anvil comprising an annular projection and at the same time creating a groove in the first piece. The annular bead is ultrasonically melted and thus welds the membrane to the first piece. The first and second pieces are then brought together so that the groove and energy director are aligned. Under ultrasonic action, the energy director melts within the groove creating a strong weldment without any voids or material flashing.