BAG-FORMING MACHINE FOR MAKING BAGS WITH CURVED BOTTOM WALLS

摘要

A machine and method for making plastic bags each having a curved or roundish-like bottom wall and an open top end is described. The machine has a bottom wall forming die having opposed concavely curved seal-forming edges converging to a common apex. The die is heated and reciprocated over a folded film sheet which is oriented such that the die will simultaneously slit heat-fuse opposed film sheets of the folded film sheet when stroked on the film sheet. The die forms opposed concavely curved seals extending from a longitudinal folded side edge of the folded film sheet and converging to an apex at a location spaced on a transverse axis from the longitudinal folded side edge. An evacuation port is located under the folded film sheet in the die-cut area of the folded film sheet and is exposed between slitting and heat-fusing strokes of the die whereby to evacuate the cut-out film portion.