Abrasive waterjet machining and method to manufacture a curved rotor blade retention slot

1. A method of machining a blade retention slot comprising: abrasive water jet machining a straight blade retention slot, wherein the slot is defined to have a height extending along a z-axis, a width extending along a y-axis, and a depth extending along the x-axis; and

abrasive water jet machining at least one side of the straight blade retention slot to generate a curved side of the blade retention slot, said curved side defined within an X-Y plane.

2. A method as recited in claim 1 , further comprising:

abrasive water jet machining the curved side of the blade retention slot into a convex side.

3. A method of machining a blade retention slot comprising:

abrasive water jet machining a straight blade retention slot, the straight blade retention slot defined along an X-axis; and

abrasive water jet machining at least one side of the straight blade retention slot to generate a curved side of the blade retention slot, said curved side defined within an X-Y plane, abrasive water jet machining the curved side of the blade retention slot into a convex side,

separating the at least one side of the straight blade retention slot into a multiple of segments along the X-axis;

defining an abrasive water jet angle for each of the multiple of segments.

4. A method as recited in claim 3 , further comprising:

positioning an abrasive water jet at the abrasive water jet angle for a first of the multiple of segments; and

moving the abrasive water jet along a jet feed direction.

5. A method as recited in claim 4 , further comprising:

moving the abrasive water jet along at least one contour of the straight blade retention slot in the jet feed direction.

6. A method as recited in claim 1 , further comprising:

abrasive water jet machining the curved side of the blade retention slot into a concave side.

7. A method of machining a blade retention slot comprising:

abrasive water jet machining a straight blade retention slot, the straight blade retention slot defined along an X-axis;

abrasive water jet machining at least one side of the straight blade retention slot to generate a curved side of the blade retention slot, said curved side defined within an X-Y plane;

abrasive water jet machining the curved side of the blade retention slot into a concave side; and

moving an abrasive water jet at a variable transverse speed to generate the concave side.

8. A method of machining a blade retention slot comprising:

abrasive water jet machining a straight blade retention slot, the straight blade retention slot defined along an X-axis;

abrasive water jet machining at least one side of the straight blade retention slot to generate a curved side of the blade retention slot, said curved side defined within an X-Y plane;

abrasive water jet machining the curved side of the blade retention slot into a concave side; and

moving the abrasive water jet along the X-axis to satisfy an empirical jet lag equation, the empirical jet lag equation having the form of:

l dr =( Aν t +B )( h 2 )+( Cν t +D )( h )

Where:

A, B, C, and D are constants related to the specific material;

ν t , is transverse velocity of AWJ cutting head;

φ, is angle of incidence;

h so , is AWJ cutting head stand-off distance;

h, is slot thickness;

h sc , is depth of smooth cutting zone, which is equal to zero for a curved slot; and

l dr is jet lag.

9. A method of machining a blade retention slot comprising:

abrasive water jet machining a straight blade retention slot, the straight blade retention slot defined along an X-axis;

abrasive water jet machining a first side of the blade retention slot into a convex side of a curved blade retention slot;

separating the first side of the straight blade retention slot into a multiple of segments along the X-axis;

defining an abrasive water jet angle for each of the multiple of segments; and

moving the abrasive water jet along a jet feed direction at an abrasive water jet angle for each of the multiple of segments and

abrasive water jet machining a second side of the blade retention slot into a concave side of the curved blade retention slot.

10. A method of machining a blade retention slot comprising:

abrasive water jet machining a straight blade retention slot, the straight blade retention slot defined along an X-axis;

abrasive water jet machining a first side of the blade retention slot into a convex side of a curved blade retention slot;

abrasive water jet machining a second side of the blade retention slot into a concave side of the curved blade retention slot; and

moving an abrasive water jet at a variable transverse speed to satisfy an empirical jet lag equation to generate the concave side, the empirical jet lag equation having the form of:

l dr =( Aν t +B )( h 2 )+( Cν t +D )( h )

Where:

A, B, C, and D are constants related to the specific material;

ν t , is transverse velocity of AWJ cutting head;

φ, is angle of incidence;

h so , is AWJ cutting head stand-off distance;

h, is slot thickness;

h sc , is depth of smooth cutting zone, which is equal to zero for a curved slot; and

l dr is jet lag.

11. A method of machining a blade retention slot comprising:

abrasive water jet machining a straight blade retention slot, the straight blade retention slot defined along an X-axis; and

moving an abrasive water jet at a variable transverse speed to satisfy an empirical jet lag equation to generate a concave side into the straight blade retention slot, the empirical jet lag equation having the form of:

l dr =( Aν t +B )( h 2 )+( Cν t +D )( h )

Where:

A, B, C, and D are constants related to the specific material;

ν t , is transverse velocity of AWJ cutting head;

φ, is angle of incidence;

h so , is AWJ cutting head stand-off distance;

h, is slot thickness;

h sc , is depth of smooth cutting zone, which is equal to zero for a curved slot; and

l dr is jet lag.

12. A system to machine a blade retention slot into a rotor disc suitable for use in a gas turbine engine comprising:

an abrasive water jet; and

a control in communication with said abrasive water jet, said control operable to move said abrasive water jet along a X-axis defined by a straight blade retention slot, to satisfy an empirical jet lag equation, the empirical jet lag equation having the form of:

l dr =( Aν t +B )( h 2 )+( Cν t +D )( h )

Where:

A, B, C, and D are constants related to the specific material;

ν t , is transverse velocity of AWJ cutting head;

φ, is angle of incidence;

h so , is AWJ cutting head stand-off distance;

h, is slot thickness;

h sc , is depth of smooth cutting zone, which is equal to zero for a curved slot; and

l dr is jet lag.

13. A method as recited in claim 1 , further comprising forming the curved side as one of a concave or convex surface extending through a depth of the slot from a fore face of a rotor disc to an aft face of the rotor disc.

14. A method as recited in claim 13 , wherein the step of abrasive water jet machining at least one side of the straight blade retention slot to generate a curved side of the blade retention slot further comprises abrasive water jet machining one side of the slot to form the concave surface extending through the depth of the slot and abrasive water jet machining an opposite side of the slot to form the convex surface extending through the depth of the slot.