| 摘要 |
1475747 Platens felting G SIEMPELKAMP & CO 22 Aug 1974 [22 Sept 1973 (2)] 36901/74 Heading D1R [Also in Division B5] Fibre sheets are made by subjecting single or multilayer mats containing fibres and fluid, e.g. wet asbestos cement mats, to compression between platens by (i) applying a pressure pulse to cause felting, and then (ii) applying a consolidation pressure to effect hardening by means of the upper platen, expressed fluid being led away before and/or during compression. The pressure pulse generates a pressure higher than the consolidation pressure and produces a shock-wave which reorients the fibres. If the mat is placed on the lower platen with the interposition of a perforated screen, a needling effect may be simulated. The pressure pulse may be produced by causing the upper platen 3 to fall freely on the mat or by the release of a pressure medium from a vessel to act on said platen; as shown, the upper platen 3 and tup 7 are driven by a piston and cylinder 8 which is actuated by a feeder 16 connected to an accumulator 15 to permit free fall. A return device 9 is provided. The pressure pulse may be so adjusted as to produce a dust layer on the surface of the compressed mat and so minimise tackiness. Moisture may be led away before and during the pulse. The compression pressure is preferably built up immediately after the pulse, if necessary before the collapse thereof. The mat may be held by vacuum on a moving screen 13 which is driven over the lower platen 2. As shown in Fig. 2, this platen is provided with a coarse web 10, a fabric 11 and a fine sieve 12. The screen 13 may be replaced by a filter cloth. The platens 2, 3 may be corrugated for producing shaped sheets. |
