Manufacture of FRP composites

Abstract

Techniques are provided for producing low-cost FRP composites which contain heavy tow fibres. Techniques are provided for uniform impregnation and efficient bonding of these heavy tow fibres which eliminates “racetracking,” thus resulting in cost-effective and well performing FRP composites.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is related to and claims priority from European Patent Application No. 05 002 047.8 filed on Feb. 1, 2005, which is incorporated by reference herein in its entirety. FIELD OF THE INVENTION [0002] The present invention relates to manufacture of fibre-reinforced plastics (FRP) composites. BACKGROUND OF THE INVENTION [0003] Composite materials and in particular CFRP (carbon fibre reinforced plastics) composite materials are characterized by their low weight, great strength and high stiffness in comparison with traditional materials such as wood, steel, aluminum etc. For these reasons, they are used in a number of applications ranging from the aerospace, construction, automotive industries to the sports and medical fields. [0004] In the 1970s, for instance, sporting good manufacturers started making use of CFRP composites in the manufacture of fishing rods, golf clubs, and tennis rackets. In the 1990s, commercial plane manu...

AI Technical Summary

Benefits of technology

[0016] One embodiment of the present invention provides a process for manufacturing a fibre-reinforced plastics (FRP) composite and to a device for carrying out such process. One embodiment of the present invention relates to a heavy tow (thick bundle) FRP-composite free of “dry spots”, a process for manufacturing such composite by preventing “racetracking,” and a device for carrying out such process. In one embodiment, the present invention advantageously provides for the manufacture of low cost FRP composites which exhibit good performance.

[0017] In view of the problems described in the background section and the need for cost reduction and process improvement, one embodiment of the invention provides a process for producing low-cost FRP composites which contain heavy tow fibres, and a method for uniform impregnation and efficient bonding of these heavy tow fibres which eliminates “racetracking”, thus resulting in cost-effective and well performing FRP composites.

[0021] According to one embodiment of the present invention, a resin used to impregnate the fibres has a low viscosity. In one embodiment, impregnation of fibres by resin can be carried out by injection of the resin into the fabric sheet. Injection of the resin into the fibre may be made at any site in the fabric area, wherein the pressure difference between the injection side and the downstream side of the resin flow may be increased stepwise.

Problems solved by technology

However, as a result of increasing attention to environmental problems, there is a tendency to try to use these composites for commercial, mass-produced cars.

However, for structural applications, thermoplastic resins have conventionally lacked the mechanical properties of thermoset resins.

Mainly, poor fibre impregnation and lack of fibre adhesion cause this performance gap.

Thermoplastic resin conventionally used in the manufacture of CFRP composites starts off with a high viscosity, typically 100-1000 Pa·s, and thus impregnation becomes a difficult task.

With RTM, one may be capable of making complex and quality composite parts with short cycle times. However, by introducing more complexity into the part, one also introduces higher probability of disturbances, such as racetracking of resin during impregnation along the preform edges.

With severe racetracking, the exiting resin can bypass some of the fibres and produce dry spots within the composite.

This results in poor quality FRP composites.

Another possible disturbance is the displacement of the fibres during the RTM process.

For example, if the matrix viscosity is too low and the timescales long, shaping pressures may cause the resin to be squeezed out of the laminate.

Alternatively, too high a viscosity coupled with a short duration can result in the fibres being unable to adjust to the flow pattern and distortion can ensue.

The introduction of high performance FRP components in a structure however significantly depends on the raw material and the manufacturing process costs.

Conventionally, the cost of FRP containing materials has been very high and often prohibitive for the general consumer.

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