Window-cutting device for envelopes and bag-making machines

Claim 1

A WINDOW-CUTTING DEVICE FOR CUTTING SEVERAL WINDOWS INTO BLANKS FOR ENVELOPE AND FLAT BAGS, SAID CUTTING DEVICE COMPRISING, IN COMBINATION, A ROTARY CUTTING ROLLER AND A COUNTER ROLLER FOR SUCCESSIVELY FEEDING BLANKS TO BE CUT THEREBETWEEN, SEVERAL CLOSED CUTTING KNIVES MOUNTED ON SAID CUTTING ROLLER, SAID CUTTING ROLLER INCLUDING PORTS IN EACH OF THE SURFACE AREAS BOUNDED BY SAID KNIVES, DUCTS FOR CONNECTING THE PORTS OF EACH KNIFE WITH A SUPPLY OF SUCTION AIR AND DUCTS FOR CONNECTING SAID PORTS WITH A SUPPLY OF PRESSURE AIR, CONTROL MEANS ACTUATED BY SAID ROTARY CUTTING ROLLER AND CONTROLLING SAID DUCTS FOR SEQUENTIALLY CONNECTING SAID PORTS AT PREDETERMINED TIME INTERVALS WITH SAID SUCTION DUCTS AND SAID PRESSURE DUCTS AND FOR DISCONNECTING SAID PORTS AT SAID PREDETERMINED TIME INTERVALS FROM SAID DUCTS, TIMING MEANS COACTING WITH SAID CONTROL MEANS FOR VARYING SAID TIME INTERVALS INDEPENDENTLY FOR THE PORTS OF EACH OF THE SAID KNIVES, GUIDE MEANS SUPPORTED ON THE PERIPHERAL WALL OF SAID CUTTING ROLLER FOR GUIDING THE LEADING EDGE OF EACH BLANK TO BE CUT, AND SETTING MEANS FOR VARYING THE CIRCUMFERENTIAL POSITION OF SAID GUIDE MEANS IN REFERENCE TO SAID CUTTING KNIVES.