Air cushion method and apparatus for supporting moving film sheets

Claim 1

IN A SYSTEM FOR TRANSPORTING A CONTINUOUS WEB OF SHEET MATERIAL THROUGH A TREATMENT ZONE IN WHICH THE DIRECTION OF WEB TRAVEL IS CHANGED ANGULARLY, AN APPARATUS FOR SUPPORTING SAID WEB OUT OF CONTACT WITH SOLID SURFACES AT A POINT AT WHICH THE DIRECTION OF WEB TRAVEL IS CHANGED, SAID APPARATUS COMPRISING (A) AN ELONGATED HOUSING HAVING A PAIR OF SIDE WALLS TAPERING OUTWARDLY FROM THE BOTTOM TO THE TOP OF SAID HOUSING, THE UPPER SURFACES OF SAID SIDE WALLS EXTENDING FOR DISTANCES SLIGHTLY GREATER THAN THE WIDTH OF SAID WEB, AND END WALLS CONNECTING SAID SIDE WALLS AND DEFINING AN OUTWARDLY FLARED ZONE WITHIN THE HOUSING; (B) AN AIR SUPPLY CONDUIT CONNECTED TO THE BOTTOM OF SAID HOUSING AND COMMUNICATING WITH THE SMALLER END OF THE OUTWARDLY FLARED ZONE THEREOF FOR CONVEYING AIR UNDER LOW PRESSURE INTO THE SAME; (C) AN ARCUATELY SHAPED, SUBSTANTIALLY RIGID PERFORATED WALL MEMBER ENCOMPASSING A CIRCULAR ANGLE SLIGHTLY GREATER THAN 180* AND PRODUCED FROM DEFORMABLE SHEET MATERIAL, THE EXTREMITIES THEREOF BEING SECURED TO THE SIDE WALLS OF SAID HOUSING AND HAVING A LENGTH SUBSTANTIALLY CORRESPONDING TO THE LENGTHS OF THE UPPER SURFACES OF SAID SIDE WALLS, SAID ARCUATE MEMBER DEFINING A CHAMBER OPEN AT ITS ENDS AND COMMUNICATING WITH THE LARGER END OF THE OUTWARDLY FLARED ZONE WITHIN SAID HOUSING; AND (D) A SHEET OF POROUS, AIR-PERMEABLE FABRIC MOUNTED ON THE PERIPHERY OF SAID ARCUATE MEMBER AND THROUGH WHICH A SMOOTH, LOW PRESSURE FLOW OF AIR DIRECTED FROM SAID HOUSING MAY PASS, THEREBY PROVIDING AN ARCUATE AIR CUSHION FOR SUPPORTING SAID WEB AS ITS DIRECTION OF TRAVEL IS ANGULARLY VARIED.