Abstracts of patents Abstracts of UK patents prepared by Dr F. R. Jones, School of Materials, University of Shefield, UK

Abstracts of US patents prepared by Dr R. J. Hand, Department of Engineering Materials, University of Shefield, UK

UK PATENTS

Bagging arrangement for synthetic resin component processing apparatus (Short Bros plc, UK) GB 22452164 (2 January 2992) For autoclave processing of prepreg based composites, a sealing edge has been incor- porated into the mould table. The vacuum bagging arrangement consists of a blanket which can be drawn to ensure that the seal with the mould table edge is maintained with varying components.

Manufacture of a composite material (Short Bros. plc, UK) GB 2245862A (IS January 1992) A stack of prepreg is precut with a blade and a tow of fibres or pre-impregnated figures (in tape form) is used to stitch the stack. Once through to the outer edge the loop is slit and the prepreg consolidated within the laminated surfaces and cured. In this way the impact resistance and interlaminar shear properties of the composite are improved. These are considered to be an improvement over known mechanical fasteners, especially in hostile environments.

Continuous process for forming fibre reinforced thermoplastic resin honeycomb structures (Northrop Corp, USA) GB 2246740A (12 February 1992) A continuous process for the production of honeycomb support structures from a plurality of corrugated thermoplastic pre- impregnated fibre sheets, is described.

US PATENTS

Method for continuously producing moulded members from a mixture of gypsum and fibrous material Bold J. (‘Wiirtex’ Maschinenbau Hofmann GmbH & Co., Uhingen, Germany) US Pat 4 942 003 (I 7 July 1990) Dry calcinated gypsum and dry fibrous material are mixed and weighed. Water, in a sufficient amount for the stoichiometric setting and curing of the material, is then added in a stepwise fashion whilst continuously stirring the mixture. The mixture is dispersed onto support means including a forming line so as to produce multi-layer moulded members which are then further moistened with an over-stoichiometric quantity of water to give construction panels with only a small or nominal bonding or binding-off and drying time with high mechanical strength and very smooth surfaces.

Composites Manufacturing No. 2 1992

Method of making reinforced plastic laminates for use in the production of circuit boards Medney J. and Klimpl F.E. (Compositech Ltd., Hauppauge, NY, USA) US Pat 4 943 334 (24 July 1990) At least one set of superposed filament sections are arranged such that the filaments are parallel within a layer at an angle to the filaments in the other layers. The filaments aligned in the same direction are substantially under the same tension and the whole is held on a form in a fixed spatial relationship. The filaments are embedded in a matrix material which is set and cured to produce the board.

Multi-tow fibre placement machine with full band width clamp, cut and restart capability Wisbey J.D. (Cincinnati Milacron Inc., Cincinnati, OH, USA) LIS Pat 4 943 338 (24 July 1990) An improved head for a fibre placement machine which has an upstream tibre source, a downstream layout zone, and a means for providing relative movement between the machine member that carries the heat and the layout zone. The head consists of a presser and a fibre guide and spacing means, movably mounted on a bracket which attaches the head to the rest of the apparatus. The fibre guide and spacer may be moved bidirectionally to an advanced position proximal to the presser and to a retracted position distal to the presser.

Process for preparation of tooling of carbon fibre reinforced polyimide for composites manufacture Gupta D. (EL Du Pont de Nemours and Company, Wilmington, DE, USA) US Pat 4 944 824 (31 July 1990) A lay-up of carbon fibre reinforced prepregs and substantially stoichiometric quantities of diamines in an amount sufficient to produce 35-45 volume % polyimide in the prepreg on cooling is enclosed in a vacuum bag and heated to 120-205°C under at least 1.3 MPa pressure. The pressure and vacuum are released whilst the whole is cooled and the assembly is then cured by heating to 370-385°C at the rate of 0.551.5”C mini until the Ts of the composite tool reaches at least 388°C without the application of external pressure but with the application of vacuum to remove polymeriza- tion products. The resulting tool may be used to fabricate high T, composite articles.

Process for dyeing concrete Jungk A.E. (Chemische Werke Brockhues AC, Walluf, Germany) CrS Pat 4 946 505 (7 August 1990) Pigmenting granules, other than compacted or briquette granules, containing at least one of iron oxide and manganese oxide are mixed with cement and aggregate such that a

homogeneous dispersion of the pigment in the concrete is achieved. The granules also contain at least one binder to aid dispersal of the pigment in the concrete, having a finite water content of not more than 4.2% and 90% of them are greater than 20 pm in size.

Method for the continuous production of chip, fibre- and similar boards Steininger H-P. (Wilheim Mende GmbH & Co., Gittelde, Germany) US Pat 4 946635 (7 August 1990) A mixture of cellulose chips and resin binder is compressed against a heated rotating drum by a steel strip. Sufficient pressure is applied as the mixture enters the gap between the drum and the strip to compress the mixture to achieve good heat transfer through it. It is then heated to 105-220°C such that both the resilience and the wetting of the chips is maximized; a higher pressure is then applied to compress the mixture to the final desired thickness as the binder hardens and binds the chips together.

Method for producing a fabric made from thermoplastic melt impregnated tow Binnersley E.K. and Batman J.M. (E.I. Du Pont de Nemours and Company, Wilmington, DE,USA) USPat 947897(14August 1990) Weft tapes are fed in a twistless manner from a variable speed rotatable supply package to a power driven loom and inserted in the weft direction through a warp shed of warp tapes with a driven movable rapier which is synchronized with the variable speed feeder to produce a woven fabric. Both the warp and weft tapes are comprised of polymer impreg- nated continuous filaments.

Method of moulding fibre reinforced glass matrix composite articles Jarmon D.C. and Minford E. (United Technologies Corporation, Hartford, CN, USA) US Pat 4 949 921 (21 August 2990) At least one ply of glass impregnated continuous fibre tape is laid up against the inner surface of a die such that a mould cavity is left. This cavity is filled with a fluid mixture of discontinuous fibres and molten glass, which is introduced into the cavity in a direction parallel to the fibres in the tape. Pressure is applied to the fluid mixture to produce a composite article with an inner core and a continuous fibre reinforced outer layer.

Moulding apparatus for tibre-filled resin Schehr D.K., Hampshire W.J. and Conger M.T. (The Goodyear Tire and Rubber Company, Akron, OH, USA) CTS Pat 4 950 149 (21 August 1990) An apparatus involves moving at least one mould with a female part and a male part on

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