JOINING METHOD FOR BOTTOM OF PAPER CUP TO AVOID TWIST OF SIDE PAPER

摘要

PURPOSE: A joining method for bottom of paper cup is provided to prevent a twist of side paper by pressing a side paper radially and not using knurling tools. CONSTITUTION: A joining method for bottom of paper cup comprises the steps of: inserting a joining expander with narrow space radially into a bottom of a paper cup; joining an inward bent part to a downward bent part by pressing them through expanding the joining expander; inserting the joining expander again with narrow space radially and aligning the middle of outside of the joining expander with unpressed protruding part; pressing the unpressed protruding part by expanding the joining expander.