| 摘要 |
1,235,224. Perforating; laminates. FORD MOTOR CO. Ltd. 30 Sept., 1969 [25 Nov., 1968], No. 47933/69. Headings B5A and B5N. [Also in Division B2] Sheet thermoplastic material is perforated by forming a plurality of closed ended depressions therein and breaking the closed ends of the depressions by heating the material and subjecting it to a fluid pressure differential. In the embodiment shown in the Figure a P.V.C. film 10, backed by a fabric layer 14, is first embossed with depressions 24 by passage between metal rollers. The thin sections 28 left at the bottom of the depressions are then ruptured by passing the material over cooled shoes 32, 34 between which is located a nozzle 30 which directs a stream of air of a temperature above the melting point of P.V.C. against the material. The backing layer is unaffected by the stream and does not rupture. |
