GB2213793A - Winding airfoil - Google Patents

Description

:j r) r) - 4 131/ C1113 METHOD FOR MANUFACTURING A THREE-DIMENSIONALLY

TWISTED_ROTOR_BLADE_AIRFOIL ------------------- r_ This invention relates to a method for the manufacture of a fibre reinforced component, particularly a threedimensionally twisted rotor blade airfoil, by wrapping a core with a resin-impregnated fibre material.

Fibre components are rapidly gaining technical significance on account of their excellent properties. Their low density, high tensile strength and relative ease of shaping invites their use in areas that had formerly been the sole domain of metallic materials.

Fibre-reinforced materials, e.g. are also finding use in aircraft applications, as for dynamically highly stressed rotor blades and propellors or for propfan airfoils.

Another outstanding property of fibre-reinforced materials is the option of influencing component properties by laying the fibres in preferred orientation to obtain different material data in different directions the modulus of elasticity or damping constants.

Technical problems are encountered, however, in the manufacture of fibrereinforced components of complex shapes with three-dimensionally twisted surfaces, especially if these take a partially concave form and if the requirements are for different strength and vibration properties in different directions. This applies particularly to modern turbine engine fan or propan blades, where the attachment of the airfoil to the root or rotor poses another specific problem.

for, e.g.

Conventional manufacture of these components is associated with considerable effort involving high manufacturing costs. It employs socalled prepegs, which are fibre panels impregnated with a matrix material and inserted in a hollow mould to be cured under pressure and heat. One disadvantage of this method is the extremely high cost involved when trying to deliberately influence component properties with it, which basically is a feasible proposition.

One object of this invent-Lon is to enable the manufacture of a fibre-reinforced component, particularly a threedimensionally twisted rotor blade airfoil by a simp-e and rapid method that permits selective manipulation of component properties by selective routing of the fibres and more particularly so as to permit ready application of fibres also to concave surfaces.

According to this invention we propose a method for the manufacture of a fibre-reinforced component such as an airfoil, particularly a threedimensionally twisted rotor blade airfoil by wrapping a core with a resin impregnated fibre material, wherein fibre strands wetted with a resin matrix are pressed against the core for example, by means of a nip roller, and the resin matrix precured immediately thereafter, preferably by a precuring facility such as an infrared radiator coupled to the nip roller.

Fibres can be applied in a simple manner, in each and every direction and on any shape of airfoil surface and t z t, I 1 1 so that they will then adhere and not subsequently become dislodged. After the fibres have precured they will adhere also to concave surfaces,. so they can be laid rapidly and accurately in position. Depending on requirements several plies of fibre can be deposited one over the other in different or identical orientations.

Precuring the matrix material causes it to gel to a point where the fibre is cemented in place before the fibre matrix mixture still is fully cured. Thereafter the wrapped component is pressed to final size in a mould and cured in a furnace.

The time needed to manufacture a twisted fibre component is substantially shorter than that expended in conventional manufacture. An essential consideration also is that concave blades can simply and accurately be covered with layers of fibre, which with the conventional methods of fibre application cannot be achieved with full satisfaction.

This much simplifies the wrapping process and so it susceptible of fully automated computer and robot controlled implementation.

The fibre strands can advantageously be laid along preferred tracks. This permits a selective anisotropic component structure to be achieved in arrangements benefiting stability and strength. This helps eliminate especially vibration problems.

In a preferred embodiment, the fibre strands are looped around a number of attaching nipples on the blade root to 1 attach the airfoil to the root. This permits a particularly favourable transfer of the centrifugal forces acting on the root in operation.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which Figure 1 is Figure 2 is laying device; Figure 3 is portal robot.

With reference now to Figure 1 the airfoil 1 of a rotor blade is shown. Depicted also are the preferred directions of the fibres to be deposited: the main tensile direction 2 and the diagonal layers 3 and 4. The fibres are preferably looped around attaching nipples on a blade root 6, so as to ensure a satisfactory union between the two components and for good transfer to the blade root 6 of the tensile force arising in operation.

The fibre laying device 8 shown in Figure 2 essentially comprises a fibre drum 10, a fibre feed duct 12 leading to a fibre nip roll 11, and a precuring facility 15. The fibre strand 9 unwound from the fibre drum 10 is pulled by the nip roll 11 through the fibre feed duct 12 into which matrix material is fed in defined from a matrix metering unit 14 through a feed The matrix material is supplied from a storage 16 to the matrix metering unit 14 through a perspective view illustrating a fan blade; perspective view illustrating a fibre and a perspective view illustrating a six-axis quantities duct 13. container Y X k 1 flexible feed line 17. The volume of matrix fed per unit length of fibre can be adjusted, preferably to suit the fibre throughput. Having been wetted in this manner the fibres are accurately laid on to the component in the desired track under the fibre nip roll 11 and are precured (gelled) by means of the precuring device 15, causing the surface to dry and stick. In this manner, the fibre is fixed to a point where it can be laid on to radiused tracks. Thereafter, further fibre layers can be deposited in any 10desired orientation over the precured fibres.

As it will become apparent from Figure 3, the fibre laying device 8 here shown in schematic arrangement is connected to the "wrist" of a six-axis portal robot 7 and can thus - under computer control - deposit the fibre 15strand 9 on the component core fully automatically along precalculated tracks. This makes for very accurate reproducibility ( <0.2 mm) of the fibre laying process.

The rough item having been manufactured in this manner, is then placed in a mould and conventionally finish 20cured under pressure and heat.

Claims (6)

1. A method for the manufacture of a fibre-reinfcrcedx component by wrapping a core with a resin-impregnated fibre material, wherein fibre strands wetted wizn a resin matrix are pressed against the core and the resin matrix precured immediately thereafter.

2. A method according to claim 1 wherein the wet-led fibre strands are pressed against the core by a nip roller having coupled thereto a resin matrix precuring facility.

3. A method according to claim 1 wherein the component is an airfoil and the fibre strands are looped around a on a blade root to secure the

4.

number of attaching nipples airfoil to the blade root (6).

A method according to claim 2, facility comprises an infrared radiator.

5. A method according to claim 2 wherein strands are drawn through a fibre - - -o wet fibre st matrix material is introduced t lrands.

6. A method for the manufacture of fibre reinforced component, particularly a three-dimensionally twisted airfoil, substantially as hereinbefore described with reference to the accompanying drawings.

wherein the Drecuring Published 1988 at The Patent Office. Statc House. 6671 High Ho'b--rr.. Lond= WC1R 47T F=.her copes mk., be ottaine-1 frorn lhe Paten, 051ce. Sales Branch, St Many Cray. Orpingzor.. Ken, BE3 3RD Printed by Multiplex tecPriTies lt-'. St, Maz-S Cray- Ken Con. 1 87