Moulding fibre reinforced structural members

Moulding fibre reinforced structural members

Abstracts of patents Abstracts of UK and US patents are supplied by Dr F. R. Jones and Dr W. E. Lee of the University of Shefield, C:K infiltration. t...

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Abstracts of patents Abstracts of UK and US patents are supplied by Dr F. R. Jones and Dr W. E. Lee of the University of Shefield, C:K infiltration. the chamber is transferred to a high pressure vessel and gas pressurized, where further impregnation takes place. The body is heated to a higher temperature (for carbonization) and the high pressure gas discharged in a controlled manner in response to the pressure generated within the high pressure vessel due to carbonization. Full details of the process are given.

UK PATENTS Three fabric

dimensional

stabiliition

of dry composite

(United Technologies Corp, USA) GB 2 222 550 A (14

March

1990)

Dry fibre laminae can be formed into a preform by compressing them between templates. The templates have openings through which the fibrous layers can be stitched in order to prepare a stable preform. This technique ensures much higher tolerances to the preforms and composites, especially those manufactured by resin transfer moulding. Internal injection

mould release moulding

agent

Moulding

tubular material

structures and method

2 223 711 A (18 April

for use in reaction

of fibre reinforced for their production

(T I Corporate Services Limited, UK) GB 1990 ) -’ --772 653 A I 14 March The title artefacts are fabricated from thin metallic tubes (e.g., aluminium) which are overwound by tape winding or with a sleeve ofpre-impregnated fibres. Either before or after resin cure, the cross-section can be changed by allowing the wound tube to collapse in a controlled manner under the influence of an external pressure from a die and an internal hydraulic pressure. The thin-walled mandrel remains in situ after cure. Moulding

composite

materials

(British Aerospace plc, UK) GB 2 222 980 A ( 28 March

1990)

A modified ‘press-clave’ technique is described in which thermoplastic prepreg can be consolidated into a complex shape. One surface of the pressure vessel forms the evacuable mould surface for the bagged-up ‘composite’, which is pressurized. Heating is accomplished in an oven. Impregnating

(Kabushiki

porous

carbon

bodies

Kaisha Kobe Seiko Sho, Japan)

GB 2 223 009 A (28

March

1990)

Carbon/carbon composites are generally manufactured from liquid precursors, such as pitch, in a multistage process which involves more than one vacuum impregnation of the molten tar pitch followed by pressure carbonization and graphitization. The pressure carbonization requires that the impregnated body is sealed into an evacuated can before hot isostatic pressing. In this disclosure, these stages are incorporated into a simpler process whereby the vacuum infiltration and carbonization are carried out stepwise without the need for a sealed can. After vacuum

Composites

Manufacturing

September

reinforced

structural

members

of Switzerland)

GB

1990)

A foam polyurethane core, wrapped with a polymeric film, is overwound with resinimpregnated fibres and then subjected to pultrusion to form an essentially longitudinal fibrous layer, which can be consolidated by overwinding with unimpregnated fibre to absorb the excess resin. The fibrous laminae are in the ratio of 8 : 100: 10. The ‘rawling’ is sufficiently flexible for forming into curved ‘rods’ or for inserting into a mould where two members can be squeezed together to form a joint. Applications in sports goods are foreseen.

(Mobay Corp, USA) GB 2 222 593 AJGB 2 222 594 A I14 March 1990) Zinc fatty acid soaps (e.g. Zn stearate) with polyurea( 593A)oramidine( 594A)containing compatibiizers for the RIM process are described. Hollow plastics

libre

(Sven Erik Malmstrom

1990

Propeller

blades

(General Electric Co, USA) GB 2 224 784 A (I6

May

1990)

An aircraft propeller blade is manufactured from two FRP epoxy laminated prepreg shells between which a titanium spar is aligned. Foamed filler pieces are adhered to the spar and outer shells with an adhesive resin which cures simultaneously during the resin curing process. Balancing weights are incorporated into the blade. A method of balancing a rota with several blades attached is described. Suggested reinforcement for the composite is 20% S-glass/lO% carbon although other fibres can be used. Fibre orientation is also described. Improvement of laminates

in and relating

to the manufacture

(Tetronel Limited, UK) GB 2 224 969 A (23 May

1990)

A core-stiffened decorative laminate is fabricated by laying the core material between two layers of (glass) fibre matting, and profiling the air side to the ribs, and impregnating with polyester resin. The resin-rich surface layer can be textured for use as (for example) a cladding panel. Resin laminate with superficial layer foil coated with pigmented resin

of metal

Slate-filled

resin

products

(Meirion Gribble of UK) GB 2 225 275 A (30 May

1990)

Slate dust/glass fibre dough moulding resin compound isextruded, thencut into rectangular sheets. These can be pressed (simultaneously) between metallic plates of which one has been cast around natural slate. On pressing and hot curing synthetic roofing slates with an appropriate impression are formed. Method articles

of fabricating fibre reinforced by resin transfer moulding

composite

(United Technologies Corp. USA) GB 2 225 577 A (30 May

1990)

Fibre preforms for composite fabrication by RTM are stabilized by dispersing a polymeric binder between the dry fabric phes. Hot air is passed through the preform to fuse the binder and bind the dry form together. Moulding a fibre reinforced hollow structure comprising skins connected by ribs

composite into a outer and inner

(Westland Helicopters Ltd. UK) GB 2 225 742 A / 13 Jurw

1990 I

Thermoplastic prepreg is wrapped around hollow mould tool parts which are nested together between the inner and outer composite skins within an external mould. Pressure can be partly applied internally by pressurizing the hollow components. The aluminium may be removed by etching. Extending members can be utilized as aerofoil end regions for support and attachment of trailing edge skins. They also form fluid-tight channels through which fluid can be passed during operation. Impregnating

Ebre

bundles

(Dow Europe, SA, Switzerland) GB 2 225 743 A (13

June

1990)

Improved resin impregnation and fibre wet-out can be achieved in, for example, the RTM process by forcing the liquid resin directly into the fibre bundles through a series of inserted hollow pins. The pins can be removed before the resin sets or may be manufactured from FRP and left inserted as a component of the composite.

US PATENTS Method structure

for production

of fibre reinforced

plastic

1990)

Kondo, K., Tsuchiya. Y., Yamazawa, Y.. Terada, M., Aoki, T., Niimi, T.. Yamamoto, T. and Matsuba. K. (Toyota, Japan) L’S Par

Novel (decorative) laminates are fabricated by pressing a stack of resin-impregnated papers. One surface has a metal foil coated with pigmented resin. The mould surface can be used to produce a variegated micro- or macro-textured surface.

The method consists of forming a fibrereinforced plastic structure having spoke portions by winding a continuous. long-stable tibre impregnated with resin around a plurality of winding jigs to a predetermined thickness.

(Formica Corp. USA) GB 2 224 972 (23 May

4 849 037 II8

July

1989 I

199