Helicopter blade mandrel

• US 20080157429A1
• Filed: 12/27/2006
• Published: 07/03/2008
• Est. Priority Date: 12/27/2006
• Status: Active Grant

• Current Assignee: Hexcel Corporation
• Original Assignee: Hexcel Corporation
• Inventors: Callis, Richard A., Newkirk, Scott, White, Jane, White, Joe
• Granted Patent: US 7,749,421 B2
• Time in Patent Office: Days
• US Class Current: 264/232
• CPC Class Codes: B29C 33/485 cores or mandrels collapsible mandrels for shaping tube ends B29C57/02; collapsible mandrels for winding and joining B29C53/824
• CPC Class Codes: B29D 22/00 Producing hollow articles tubular articles B29D23/00; pneumatic tyres B29D30/00
• CPC Class Codes: B29D 99/0028 hollow blades
• CPC Class Codes: B29L 2031/082 Blades, e.g. for helicopters
• CPC Class Codes: Y10T 156/1002 with permanent bending or reshaping or surface deformation of self sustaining lamina

Abstract

Methods and apparatus are provided for making a rotor blade spar from composite material wherein a multi-component mandrel is used to form the composite spar. The mandrel is made using a number of components, which are assembled to provide a structure that is sufficiently strong to maintain the spar shape during pre-cure lay up, compaction and curing of the composite material. The multiple components used to form the mandrel can be separated from each other and easily removed from the spar either before or after curing of the composite material. The mandrel components can then be re-assembled and re-used to form additional composite spars.

Claims

1. A mandrel for use in molding a helicopter rotor blade wherein said rotor blade includes a spar that extends parallel to the longitudinal axis of said rotor blade, said longitudinal axis extending from the root of said rotor blade to the tip of said rotor blade, said spar having interior surfaces that defines a spar cavity that also extends longitudinally from the root of said rotor blade to the tip of said rotor blade, said spar interior surfaces including a leading edge surface that comprises an upper leading edge portion and a lower leading edge portion, a trailing edge surface that comprises an upper trailing edge portion and a lower trailing edge portion, an upper surface that extends between said leading edge upper portion and said trailing edge upper portion and a lower surface that extends between said leading edge lower portion and said trailing edge lower portion, said mandrel comprising:

a forward component that comprises an exterior surface that is shaped to provide said leading edge surface of said spar interior surfaces, said forward component comprising an upper rear edge comprising an outer surface that is shaped to provide said upper leading edge portion and a lower rear edge that is shaped to provide said lower leading edge portion;

a rearward component that is shaped to provide said trailing edge surface of said spar interior surfaces, said rearward component comprising an upper forward edge that is shaped to provide said upper trailing edge portion and a lower forward edge that is shaped to provide said lower trailing edge portion;

an upper component that is shaped to provide said upper surface of said spar interior surfaces, said upper component comprising a forward edge that is connected to said upper rear edge of said forward component and a rearward edge that is connected to said upper forward edge of said rearward component;

a lower component that is shaped to provide said lower surface of said spar interior surfaces, said lower component comprising a forward edge that is connected to said lower rear edge of said forward component and a rearward edge that is connected to said lower forward edge of said rearward component; and

a collapsible support structure located between said upper component and said lower component, said support structure being collapsible when a tensioning force is applied to said support structure along the longitudinal axis of said rotor blade.

2. A mandrel for use in molding a helicopter rotor blade according to claim 1 wherein said collapsible support structure comprises a corrugated material that comprises ridges which extend substantially perpendicular to said longitudinal axis.

3. A mandrel for use in molding a helicopter rotor blade according to claim 2 wherein said collapsible support structure comprises a forward piece of corrugated material and a rearward piece of corrugated material.

4. A mandrel for use in molding a helicopter rotor blade according to claim 2 wherein said corrugated material comprises a composite material.

5. A mandrel for use in molding a helicopter rotor blade according to claim 2 wherein said corrugated material comprises a forward edge and a rearward edge and wherein the lateral distance between the ridges of said corrugated material decreases from the forward edge of said corrugated material to the rearward edge of said corrugated material.

6. A mandrel for use in molding a helicopter rotor blade according to claim 1 wherein the connections between said forward component and said upper and/or lower components are releasable connections.

7. A mandrel for use in molding a helicopter rotor blade according to claim 1 wherein the connections between said rearward component and said upper and/or lower components are releasable connections.

8. A mandrel for use in molding a helicopter rotor blade according to claim 1 wherein the forward edge of said upper component overlaps the upper rearward edge of said forward component on the inside thereof and wherein the forward edge of said lower component overlaps the lower rearward edge of said forward component on the inside thereof.

9. A mandrel for use in molding a helicopter rotor blade according to claim 1 wherein the rearward edge of said upper component overlaps the upper forward edge of said rearward component on the inside thereof and wherein the rearward edge of said lower component overlaps the lower forward edge of said rearward component on the inside thereof.

11. A method for molding a helicopter rotor blade wherein said rotor blade includes a spar that extends parallel to the longitudinal axis of said rotor blade, said longitudinal axis extending from the root of said rotor blade to the tip of said rotor blade, said spar having interior surfaces that defines a spar cavity that also extends longitudinally from the root of said rotor blade to the tip of said rotor blade, said spar interior surfaces including a leading edge surface that comprises an upper leading edge portion and a lower leading edge portion, a trailing edge surface that comprises an upper trailing edge portion and a lower trailing edge portion, an upper surface that extends between said leading edge upper portion and said trailing edge upper portion and a lower surface that extends between said leading edge lower portion and said trailing edge lower portion, said method comprising the steps of:

providing a mandrel according to claim 1;

applying uncured composite material to the exterior surface of said mandrel to form an uncured spar;

collapsing said collapsible support structure;

removing said mandrel from said spar cavity; and

curing said uncured spar.

12. A method for molding a helicopter rotor blade according to claim 11 wherein said collapsible support structure comprises a corrugated material that comprises ridges which extend substantially perpendicular to said longitudinal axis.

13. A method for molding a helicopter rotor blade according to claim 12 wherein said collapsible support structure comprises a forward piece of corrugated material and a rearward piece of corrugated material.

14. A method for molding a helicopter rotor blade according to claim 12 wherein said corrugated material comprises a resilient material.

15. A method for molding a helicopter rotor blade according to claim 12 wherein said corrugated material comprises a forward edge and a rearward edge and wherein the lateral distance between the ridges of said corrugated material decreases from the forward edge of said corrugated material to the rearward edge of said corrugated material.

16. A method for molding a helicopter rotor blade according to claim 11 wherein the connections between said forward component and said upper and/or lower components are releasable connections.

17. A method for molding a helicopter rotor blade according to claim 11 wherein the connections between said rearward component and said upper and/or lower components are releasable connections.

18. A method for molding a helicopter rotor blade according to claim 11 wherein the forward edge of said upper component overlaps the upper rearward edge of said forward component on the inside thereof and wherein the forward edge of said lower component overlaps the lower rearward edge of said forward component on the inside thereof.

19. A method for molding a helicopter rotor blade according to claim 11 wherein the rearward edge of said upper component overlaps the upper forward edge of said rearward component on the inside thereof and wherein the rearward edge of said lower component overlaps the lower forward edge of said rearward component on the inside thereof.

10. A method for making a mandrel for use in molding a helicopter rotor blade wherein said rotor blade includes a spar that extends parallel to the longitudinal axis of said rotor blade, said longitudinal axis extending from the root of said rotor blade to the tip of said rotor blade, said spar having interior surfaces that defines a spar cavity that also extends longitudinally from the root of said rotor blade to the tip of said rotor blade, said spar interior surfaces including a leading edge surface that comprises an upper leading edge portion and a lower leading edge portion, a trailing edge surface that comprises an upper trailing edge portion and a lower trailing edge portion, an upper surface that extends between said leading edge upper portion and said trailing edge upper portion and a lower surface that extends between said leading edge lower portion and said trailing edge lower portion, said method comprising the steps of:

providing a forward component that comprises an exterior surface that is shaped to provide said leading edge surface of said spar interior surface, said forward component comprising an upper rear edge comprising an outer surface that is shaped to provide said upper leading edge portion and a lower rear edge that is shaped to provide said lower leading edge portion;

providing a rearward component that is shaped to provide said trailing edge surface of said spar interior surface, said rearward component comprising an upper forward edge that is shaped to provide said upper trailing edge portion and a lower forward edge that is shaped to provide said lower trailing edge portion;

providing an upper component that is shaped to provide said upper surface of said spar interior surface, said upper component comprising a forward edge and a rearward edge;

providing a lower component that is shaped to provide said lower surface of said spar interior surface, said lower component comprising a forward edge that is connected to said and a rearward edge that is connected to said lower forward edge of said rearward component;

providing a collapsible support structure;

connecting said forward edge of said upper component to the upper rear edge of said forward component;

connecting said rearward edge of said upper component to the upper forward edge of said rearward component;

connecting said forward edge of said lower component to the lower rear edge of said forward component; and

connecting said rearward edge of said lower component to the lower forward edge of said rearward component wherein said upper, lower, forward and rearward components are connected together such that said collapsible corrugated structure is located between said upper component and said lower component, said support structure being collapsible when a tensioning force is applied to said support structure along the longitudinal axis of said rotor blade.

20. A helicopter rotor blade made according the method set forth in claim 10.