PAPER CUP BOTTOMS AND METHODS AND APPARATUS FOR FORMING SAME

摘要

A bottom for a paper cup is formed by advancing a punch against a paperboard web to push the web against a cutting edge which cuts out a circular cup bottom blank from the web. The punch is kept in a forward state to clamp an outer peripheral portion of the blank immovably against a surface of a sleeve. A reciprocable draw is advanced against a center portion of the blank to push the center portion into a circular opening of the sleeve while maintaining the clamping force, to cause the center portion of the blank to become stretched. The clamping force is then progressively released to permit the outer peripheral portion to enter the opening and become bent to form a lip extending at a substantially right angle. The lip is compressed within a gap formed between the draw and a surface of the opening. Because of the stretching of the blank, pleats formed in the lip are only in the form of micropleats that are flattened in a non-folded over state.