Hybrid composite-metal shaft

Patent metadata

Field	Value
Publication number	US-9821520-B2
Application number	US-201514662406-A
Country	US
Kind code	B2
Filing date	Mar 19, 2015
Priority date	Mar 19, 2015
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

A method for making a composite-metal hybrid shaft for a rotorcraft includes providing a tubular metal member that has an internal surface defining a space therein, preparing a composite member using a curing tool, curing the composite member, creating a cured composite member, expanding the metal member with heat, placing the cured composite member into the space defined by the internal surface of the expanded metal member, and allowing the expanded metal member to cool.

First claim

The invention claimed is:

1. A method for making a composite-metal hybrid shaft for a rotorcraft, comprising:
providing a tubular metal member that includes an internal surface defining a space therein;
providing a curing tool;
preparing a composite member by placing a plurality of composite layers onto the curing tool, wherein the plurality of composite layers consists of a carbon-reinforced epoxy material;
placing a sacrificial fiberglass layer on the composite member, the fiberglass layer being an outer layer with respect to all layers of carbon-reinforced epoxy material;
curing the composite member with the outer fiberglass layer, creating a cured composite member;
expanding the metal member with heat, creating an expanded metal member;
placing the cured composite member completely into the space defined by the internal surface of the expanded metal member; and
allowing the expanded metal member to cool;
wherein the cured composite member reinforces the composite-metal hybrid shaft.

2. The method of claim 1 , wherein the metal member is steel.

3. The method of claim 1 , wherein the internal surface of the metal member has a groove.

4. The method of claim 1 , wherein the external surface of the metal member has a groove.

5. The method of claim 1 , wherein preparing the composite member on the curing tool comprises braiding prepreg material around the curing tool.

6. The method of claim 1 , wherein preparing the composite member on the curing tool comprises wrapping prepreg material around the curing tool.

7. The method of claim 1 , wherein preparing the composite member on the curing tool comprises molding in at least one of a taper and a fillet at an end portion of the composite member.

8. The method of claim 1 , further comprising machining the outer fiberglass layer, but not the composite member, to correspond to the internal surface of the metal member.

9. The method of claim 1 , further comprising machining a taper on the composite member.

10. The method of claim 1 , further comprising machining a fillet on the composite member.

11. The method of claim 1 , wherein the method further comprises placing an adhesive onto the outer fiberglass layer.

12. The method of claim 1 , wherein the method further comprises freezing the cured composite member prior to placing the cured composite member into the space defined by the internal surface of the expanded metal member.

13. The method of claim 1 , wherein curing the composite member with the outer fiberglass layer occurs in an autoclave.

14. The method of claim 1 , wherein curing the composite member with the outer fiberglass layer occurs outside of an autoclave.

15. The method of claim 1 , wherein curing the composite member with the outer fiberglass layer occurs in a vacuum.

16. The method of claim 1 , further comprising cooling a middle portion of the expanded metal member prior to cooling an end portion of the expanded metal member.

17. The method of claim 16 , wherein a cooling fluid is used to cool the middle portion of the expanded metal member such that the middle portion of the expanded metal member is compressed onto the composite member prior to the end portion of the expanded metal member is compressed onto the composite member.

18. The method of claim 17 , wherein the cooling fluid is liquid nitrogen.

19. The method of claim 1 wherein, the internal surface of the metal member includes a surface texture to improve load transfer between the cured composite member and the metal member.

20. The method of claim 8 wherein:
the internal surface of the metal member has at least one groove or slot, and
machining the fiberglass layer includes machining a shape corresponding to the at least one groove or slot.

Assignees

• Bell Helicopter Textron Inc

Inventors

• Kendrick Phillip A

Classifications

• B29C66/72141

  Fibres of continuous length · CPC title

• B29C66/742

  to metals or their alloys · CPC title

• B29C65/665 Primary

  using shrinking during cooling · CPC title

• B29C66/30325

  making use of cavities belonging to at least one of the parts to be joined · CPC title

• B29K2063/00

  Use of {EP, i.e.} epoxy resins {or derivatives thereof}, as moulding material · CPC title