Rotor blade spar manufacturing apparatus and method

• US 9,144,944 B1
• Filed: 10/27/2011
• Issued: 09/29/2015
• Est. Priority Date: 09/09/2010
• Status: Active Grant

• Current Assignee: Skyworks Global Inc.
• Original Assignee: Groen Brothers Aviation Inc.
• Inventors: White, Robert Owen
• Primary Examiner(s): BELL, WILLIAM P
• Application Number:
  US13/317,749
• Time in Patent Office: 1,433 Days
• Field of Search: 425/419, 425/508, 425/509, 264/327, 264/40.1, 264/40.3, 264/40.5, 264/313, 264/316, 156/282, 156/307.1, 244/123.8, 244/123.9, 244/123.14, 700/206
• US Class Current: 1/1
• CPC Class Codes: B29C 2035/0211 resistance heating B29C2035/0811 takes precedence
• CPC Class Codes: B29C 33/02 with incorporated heating or cooling means
• CPC Class Codes: B29C 35/0288 Controlling heating or curing of polymers during moulding, e.g. by measuring temperatures or properties of the polymer and regulating the process controlling or regulating chemical, physical or physico- chemical processes in general B01J19/0006
• CPC Class Codes: B29C 35/16 Cooling cooling extruded material B29C48/911; cooling preforms for blow moulding B29C49/6427; cooling blown articles B29C49/66; cooling tyres during post cure inflation B29D30/0643
• CPC Class Codes: B29C 37/0064 of reinforced material
• CPC Class Codes: B29C 70/345 using matched moulds
• CPC Class Codes: B29C 70/462 Moulding structures having an axis of symmetry or at least one channel, e.g. tubular structures, frames
• CPC Class Codes: B29L 2031/082 Blades, e.g. for helicopters
• CPC Class Codes: B64C 2027/4736 from composite materials
• CPC Class Codes: B64C 27/473 Constructional features
• CPC Class Codes: B64F 5/10 Manufacturing or assembling aircraft, e.g. jigs therefor

Abstract

Apparatus and methods are disclosed for manufacture of a composite rotor blade spar having non-uniform wall thickness. Tooling for manufacturing include a first mold defining a first mold surface and a second mold comprising a rigid layer and a heated layer secured to the rigid layer and defining a second mold surface. A plurality of heating elements embedded in the second mold are activated according to a plurality of different temperature progressions effective to cure portions of the uncured composite blade spar positioned between the first and second mold surfaces coextensive with each heating element of the plurality of heating elements. In some embodiments, the second mold defines a root portion and first and second branch portions. A shear web is placed between the first and second branch portions and is bonded to a blade spar skin surrounding the second mold during curing of the blade spar skin.

Claims

1. A method for manufacturing a rotor blade comprising:

placing an uncured composite blade spar having a non-uniform wall thickness between first and second molds, the first mold defining a first mold surface and the second mold comprising a rigid core and a heated layer secured thereto, the heated layer defining a second mold surface such that the uncured composite blade spar is positioned between the first and second mold surfaces, the second mold further comprising a plurality of heating elements embedded therein; and

simultaneously activating the plurality of heating elements according to a plurality of different temperature progressions effective to cure portions of the uncured composite blade spar coextensive with each heating element of the plurality of heating elements, each temperature progression of the plurality of different temperature progressions being defined according to a thickness of a region of the composite blade spar over the heating element of the plurality of heating elements corresponding to the each temperature progression;

wherein the heated layer includes a thermally expandable material having a non-uniform thickness corresponding to pressure requirements for curing the composite blade spar in accordance with the non-uniform wall thickness;

wherein the plurality of different temperature progressions are effective to cause the thermally expandable material to apply non-uniform pressure to the uncured composite blade spar.

2. The method of claim 1, wherein the uncured composite blade spar is hollow such that one of the first mold surface and the second mold surface defines a contour of an outer surface of the uncured composite blade spar and the other of the first mold surface and second mold surface defines a contour of the inner surface of the uncured composite blade spar.

3. The method of claim 1, wherein:

the second mold surface defines the contour of the inner surface of the uncured composite blade spar; and

the second mold defines a root portion and first and second branch portions, the branch portions securing to the root portion and extending between the root portion and the distal end, the branch portions defining a gap therebetween.

4. The method of claim 3, wherein:

the first branch portion defines a first wall;

the second branch portion defines a second wall;

the first and second walls define the gap; and

the method further comprises placing a shear web between the first and second walls prior to placing the uncured composite blade spar between the first and second molds.

5. The method of claim 4, wherein the first and second walls have a helical contour.

6. The method of claim 4, wherein:

the shear web is pre-cured; and

the plurality of heating elements are positioned to be non-coextensive with the first and second walls.

7. The method of claim 1, wherein:

the uncured composite blade spar has a proximal end and a distal end; and

the non-uniform wall thickness decreases with distance from the proximal end.

8. The method of claim 1, further comprising:

securing a leading edge fairing and trailing edge fairing to opposing sides of the composite blade spar after curing the composite blade spar, the leading edge and trailing edge fairings extending along a major portion of the composite blade spar.

9. The method of claim 8, wherein securing the leading edge and trailing edge fairings to the composite blade spar comprises securing the leading edge and trailing edge fairings to the composite blade spar by means of adhesive.

10. The method of claim 8, wherein:

the uncured composite blade spar comprises a plurality of ply allocations; and

placing the uncured composite blade spar having the non-uniform wall thickness between the first and second molds comprises, for each ply allocation placing the ply allocation between the first and second molds, and debulking the ply allocation.

11. The method of claim 10, wherein debulking the ply allocation comprises applying both heat and pressure.

12. The method of claim 1, wherein a plurality of pressure sensors are embedded in the heated layer, the method further comprising:

controlling activation of the plurality of heating elements according to outputs of the plurality of pressure sensors.

13. The method of claim 12, further comprising:

controlling activation of the plurality of heating elements according to outputs of the plurality of pressure sensors such that the plurality of pressure sensors detect different pressures corresponding to desired pressures for a plurality of zones of the uncured composite blade spar in accordance with cure dynamics of the non-uniform wall thickness within the plurality of zones.

14. The method of claim 1, wherein the thermally expandable material has a non-uniform layer thickness across the plurality of heating elements effective to provide a desired non-uniform pressure in accordance with cure dynamics of the non-uniform wall thickness of the uncured composite blade when the plurality of heating elements are activated according to the plurality of different temperature progressions.