Alpha case removal process for a main rotor blade spar

Patent metadata

Field	Value
Publication number	US-10155298-B2
Application number	US-201113332440-A
Country	US
Kind code	B2
Filing date	Dec 21, 2011
Priority date	Dec 21, 2011
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

A method of removing an alpha case from a rotor blade by directing a water jet to mill a surface of a rotor blade spar to remove an Alpha-case therefrom.

First claim

What is claimed is:

1. A method of removing an alpha case from a rotor blade comprising:
mixing an abrasive with a water jet to generate an abrasive jet; and
directing the abrasive jet at a surface of a rotor blade spar to remove Alpha-case oxidation therefrom.

2. The method as recited in claim 1 , further comprising mixing garnet as said abrasive at 4 lbs/of garnet per minute.

3. The method as recited in claim 2 , further comprising directing the abrasive jet at a pressure of 10-50 KSI and a travel speed of 40-80 sq.in./minute.

4. The method as recited in claim 3 , further comprising directing the water jet at a skimming angle between 45 and 90 degrees.

5. The method as recited in claim 1 , further comprising performing a sanding process subsequent tot said water jet to achieve a desired surface finish requirement.

6. The method as recited in claim 1 , further comprising mixing garnet #120 as an abrasive at 4 lbs/of garnet per minute at 40 sq.in./minute to provide a surface effect 0.002 deep with a finish of 135 RA.

7. The method as recited in claim 1 , further comprising mixing garnet #120 as an abrasive at 4 lbs/of garnet per minute at 80 sq.in./minute to provide a surface effect 0.001 deep with a finish of 155 RA.

8. The method as recited in claim 1 , further comprising mixing 220 Silicon Carbide as an abrasive at 4 lbs/ per minute at 28 sq.in./minute to provide a surface effect 0.001 deep with a finish of 38 RA.

9. The method as recited in claim 1 , further comprising mixing 220 Aluminum Oxide as an abrasive at 4 lbs/ per minute at 56 sq.in./minute to provide a surface effect 0.001 deep with a finish of 50 RA.

10. The method as recited in claim 1 , wherein the rotor blade spar is part of a rotor blade for a rotary wing aircraft.

11. The method as recited in claim 1 , wherein the Alpha-case includes an alpha-embrittled zone of oxygen-enriched alpha phase on said surface of said rotor blade spar.

12. The method as recited in claim 11 , wherein said rotor blade spar is titanium and said Alpha-case is formed on said surface of the titanium.

13. A system to mill a rotor blade spar comprising:
a fixture to receive a rotor blade spar;
a water jet system to index upon said rotor blade spar, said water jet system includes a nozzle which defines nozzle diameter of between 0.014-0.016 inches (0.36-0.41 mm) and an abrasive mixed with the water jet to generate an abrasive jet; and
a control system to direct said abrasive water jet at a surface of a rotor blade spar to remove Alpha-case oxidation therefrom.

14. The system as recited in claim 13 , wherein the rotor blade spar is part of a rotor blade for a rotary wing aircraft.

15. The system as recited in claim 13 , wherein the Alpha-case includes an alpha-embrittled zone of oxygen-enriched alpha phase on said surface of said rotor blade spar.

16. The system as recited in claim 13 , wherein said rotor blade spar is titanium and said Alpha-case is formed on said surface of the titanium.

17. The system as recited in claim 13 , wherein said control system includes a controller configured to direct said abrasive water jet.

Assignees

• Araujo Robert J
• Mukherji Tapas K
• Sikorsky Aircraft Corp

Inventors

• Araujo Robert J
• Mukherji Tapas K

Classifications

• B24C1/086 Primary

  Descaling; Removing coating films · CPC title

• Y10T29/49318

  Repairing or disassembling · CPC title

• B64F5/30

  Cleaning aircraft · CPC title

• B64F5/40

  Maintaining or repairing aircraft · CPC title

• B64C2027/4736

  from composite materials · CPC title