GB528062A - Improvements in or relating to composite structures comprising plastic material - Google Patents

Abstract

528,062. Compound sheet materials; mouldings. DE HAVILLAND AIRCRAFT CO., Ltd., and KING, E. P. April 21, 1939, No. 12072. [Class 140] [Also in Group V] Compound sheet material comprising a reinforced core of thermoplastic material, e.g., expanded or cellular yulcanized rubber of low density interposed between layers of a different material of greater density, e.g., wood veneer or wood plies impregnated with phenol formaldehyde resin, thermoplastic resin or metal or clad metal or surrounded by a covering of such material comprises moulding the thermoplastic material round the reinforcement while the latter is under tension and maintaining tension until the material has become rigid. The reinforcing material may be strips of phenolformaldehyde resin containing fillers such as wood slivers, textile fabrics and threads, wood veneers, textile fabrics and tapes impregnated with a plastic composition, woven wire or metal strip which may be perforated and if desired provided with outwardly extending edges to form keys of U or Z-section. Woven wire may be covered with plastic composition or plasticimpregnated fibrous material. Both longitudinal and transverse reinforcing members may be used and interconnected if desired. The material shown in Fig. 3 may be made with the aid of the jig shown in Fig. 1. Nuts 7, 8 bearing on a stretcher bar 2 are first tightened to compress springs 5, 6, and reinforcing strips 9 are secured on opposite ends of the frame 1 by wires 10, 11, after which nuts 7, 8 are slackened off to allow springs 5, 6 to exert tension on the strips 9. The jig is covered with a metal sheet 14, placed in a press and thermoplastic material 16 is introduced between the strips. A second metal sheet 15 is then placed over the plastic composition, the press closed and the structure subjected to heat and pressure. After cooling the product is removed from the jig.