GB1560829A - Manufacture of propeller blades - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO THE MANUFACTURE OF PROPELLER BLADES (71) We, HAWKER SIDDELEY DYNAMICS LIMITED, a British Company of Manor Road, Hatfield, Hertfordshire, AL10 9LL, England do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to the manufacture of propeller blades. In our previous patent specification No. 1291562, there is disclosed a method of manufacturing an elongated fibre-reinforced composite member, such as a propeller blade.In that previous method, a former having an internal contour of one half of the finished blade is used to receive carbon whiskers which are laid wetted with liquid synthetic resin along the length of the intended blade shell and are left in a dry state to protrude at the shank end. Once the two halves of the shell are moulded they are bonded together and then the dry carbon whiskers are impregnated with liquid resin and compressed between male and female moulds to produce a flanged root of homogeneous one-piece structure.

The present invention is concerned with an alternative method of forming the root end. According to this invention, there is provided a method of making a propeller blade of composite fibre-reinforced synthetic resin construction, wherein two half blades with shank ends are moulded and bonded together to form a blade with a tubular shank, and the blade root is completed by a) winding around the shank fibre or yarn reinforcement impregnated with curable synthetic resin; b) then moulding the wound shank to final shape before the curing of the resin is completed; and c) thereafter completing the curing of the resin.

Forms of blade root construction in accordance with the invention will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a diagrammatic pictorial view of a half-blade and shank, Figure 2 shows the wound shank in longitudinal section, and Figure 3 shows the wound shank with an outer sleeve and a core member added.

In Fig. 1, the half shell of a blade 1, which may have bonded on to the outer surface an abrasive material such as KEV LAR (Registered Trade Mark) 49, is mould ded in a fibre-reinforced synthetic resin material, the mould including at the root end of the blade a parallel shank portion 2. The half shell is removed from the mould and bonded to a corresponding half shell, the bond preferably lying along a plane containing the neutral axis of the blade.The resulting shank becomes a tubular member which is then wound, as shown in Fig. 2, with fibre or yarn reinforcement impregnated with curable liquid synthetic resin overlaid to produce a taper end 3, it being understood that certain metal members, such as a bearing member to cooperate with a roller thrust race of a variable pitch mechanism on a propeller hub, are placed upon the shank before it is overlaid so that the winding operation incorporates them in the blade root. The overlaid shank end is then shaped or moulded within male and female moulds to produce the required root form and the root, together with the whole blade, may then be heat-treated to complete the cure of the resin.

In an alternative construction, shown in Fig. 3, the root end 3 is formed as previously described except that it is surrounded by an appropriately shaped steel sleeve 4 bonded in place and upon which sleeve, bearing and other associated metal components for a variable pitch mechanism may be mounted.

In a further development, a core mem ber 5 may be bonded within the shank to form part of a load bearing spar upon which the blade is mounted.

The term 'propeller blade' as used in this specification is intended to include both blades that themselves impel fluid and blades that are rotated by fluid movement over them. Thus, the invention is applicable to both propeller blades used for the propulsion of vehicles and also wind-driven blades for powering e.g. electricity generators.

WHAT WE CLAIM IS: 1. A method of making a propeller blade of composite fibre-reinforced synthetic resin construction, wherein two half-blades with shank ends are moulded and bonded together to form a blade with a tubular shank, and the blade root is completed by a) winding around the shank fibre or yarn reinforcement impregnated with curable synthetic-resin; b) then moulding the wound shank to final shape before the curing of the resin is completed; and c) thereafter completing the curing of the resin.

2. A method according to claim 1, wherein one or more metal members are placed upon the shank before winding and incorporated in the blade root by the winding operation.

3. A method according to claim 1, wherein a metal sleeve member is bonded around the wound shank.

4. A method according to claim 1 or claim 2 or claim 3, wherein a core member is bonded within the shank end.

5. A method of making a propeller blade, substantially as described with reference to Figures 1 and 2 of the accompanying drawings, or as modified according to Figure 3.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. ber 5 may be bonded within the shank to form part of a load bearing spar upon which the blade is mounted. The term 'propeller blade' as used in this specification is intended to include both blades that themselves impel fluid and blades that are rotated by fluid movement over them. Thus, the invention is applicable to both propeller blades used for the propulsion of vehicles and also wind-driven blades for powering e.g. electricity generators. WHAT WE CLAIM IS:

1. A method of making a propeller blade of composite fibre-reinforced synthetic resin construction, wherein two half-blades with shank ends are moulded and bonded together to form a blade with a tubular shank, and the blade root is completed by a) winding around the shank fibre or yarn reinforcement impregnated with curable synthetic-resin; b) then moulding the wound shank to final shape before the curing of the resin is completed; and c) thereafter completing the curing of the resin.

2. A method according to claim 1, wherein one or more metal members are placed upon the shank before winding and incorporated in the blade root by the winding operation.

3. A method according to claim 1, wherein a metal sleeve member is bonded around the wound shank.

4. A method according to claim 1 or claim 2 or claim 3, wherein a core member is bonded within the shank end.

5. A method of making a propeller blade, substantially as described with reference to Figures 1 and 2 of the accompanying drawings, or as modified according to Figure 3.