Rotary serrated tube punch with internal back-up for a film web and method of punching holes therewith

Abstract

A method of accurately punching holes into a moving web of a thermoplastic film material, and more particularly, punching holes into the web through the intermediary of a rotary serrated tube punch. The invention relates to accurately punching holes into an advancing web of thermoplastic film material utilizing a novel rotary serrated tube punch. The film web is continuously advanced over at least a portion of the circumferential surface of a rotatable anvil roll, and tensioned against the anvil roll surface through the use of suitable tensioning devices, such as tension rollers arranged upstream and downstream of the anvil roll. At least one opening is formed in the circumferential surface of the anvil roll which is smaller than the size of the hole which is desired to be punched into the film web through the use of the inventive rotary tube punching arrangement. An annular groove extends about the hole in the surface of the anvil roll, forming a land between the hole and the groove. The rotary tube punch possesses a serrated cutting edge at its radially outermost end, and is adapted to be rotated in synchronism with the anvil roll so as to cause the serrated cutting edge pierce through the web in a precisely aligned position with the groove in the rotating anvil roll, with the film web being supported on the land about the hole and on the anvil roll surface externally of the punch, and to thereby produce an accurately dimensioned hole in the moving web without the necessity for stopping the web. The anvil roll may be constructed hollow, and communicates with a suctioning source for aspirating punched out film material segments.

Dependencies are inferred from the claim text.