Apparatus for the transverse cutting of films, tapes, or the like, of thermoplastic material

Claim 1

A HOT-WIRE APPARATUS FOR TRANSVERSELY SEVERING A THIN SHEET OF ORGANO-PLASTIC MATERIAL, COMPRISING A TRANSVERSE SEVERING RESISTOR WIRE, A FRAMEWORK HAVING A TRANSVERSE CROSS-MEMBER AND TWO OPPOSITE SUPPORT ARMS CARRIED BY THE CROSS-MEMBER, THE SEVERING WIRE BEING CARRIED BY THE ARMS TRANSVERSELY OF THE SHEET, MEANS FOR PIVOTEDLY SUPPORTING THE CROSS-MEMBER, MEANS FOR PIVOTING THE ARMS TO ADVANCE THE WIRE TO AND THROUGH THE SHEET PARALLELLY TO THE SURFACE THEREOF, THE RADIUS OF ROTATION OF THE WIRE BEING ONLY SLIGHTLY GREATER THAN THE DISTANCE OF THE PIVOT AXIS OF THE SAID ROTATION TO THE SHEET, WHEREBY THE DIRECTION OF MOVEMENT OF THE WIRE AS IT CAUSES PARTING OF THE SHEET IS PREDOMINANTLY TANGENTIAL TO THE SHEET, ROLL MEANS FOR COLLECTING THE SHEET OF MATERIAL AND FOR MOVING THE SHEET IN A DIRECTION OPPOSITE SAID DIRECTION OF MOVEMENT OF THE WIRE AS THE WIRE CAUSES PARTING OF THE SHEET, ELECTRIC CIRCUIT MEANS FOR PASSING HEATING CURRENT THROUGH THE WIRE DURING A LIMITED PERIOD INITIATED AT A PREDETERMINED TIME DURING THE ADVANCING OF THE WIRE AND PRIOR TO THE CONTACTING OF THE SHEET BY THE WIRE, SAID TIME BEING DETERMINED SO AS TO PERMIT THE WIRE TO REACH A PREDETERMINED SHEET-SEVERING TEMPERATURE, SAID CIRCUIT MEANS INCLUDING A FIRST ELECTRIC CONTACT ELEMENT PIVOTING CONJOINTLY WITH THE ARMS AND A SECOND STATIONARY OPPOSED CONTACT ELEMENT WITH WHICH SAID FIRST CONTACT ELEMENT MAKES ELECTRIC CONNECTION ONLY DURING A PREDETERMINED PORTION OF THE MOVEMENT OF THE WIRE.