Method of machining using an automatic tool path generator adapted to individual blade surfaces on an integrally bladed rotor

• US 8,844,132 B2
• Filed: 07/22/2011
• Issued: 09/30/2014
• Est. Priority Date: 07/22/2011
• Status: Active Grant

• Current Assignee: Pratt & Whitney Canada Corporation (Rtx Corporation)
• Original Assignee: Pratt & Whitney Canada Corporation (Rtx Corporation)
• Inventors: Blais, Mario, Bellerose, Michel
• Primary Examiner(s): Taousakis, Alexander P
• Application Number:
  US13/188,570
• Publication Number:
  US 20130019477A1
• Time in Patent Office: 1,166 Days
• Field of Search: 295/57, 295/58, 298/891, 298/892.3, 298/897, 700/61, 700/98, 700/105, 700/118, 700/160, 700/163, 700/190, 700/193, 408/1.R, 409/80, 409/132
• US Class Current: 29/889.23
• CPC Class Codes: B23C 2215/44 Turbine blades
• CPC Class Codes: B23C 3/18 for shaping screw-propellers, turbine blades, or impellers
• CPC Class Codes: G05B 19/4207 in which a model is traced or scanned and corresponding data recorded
• CPC Class Codes: G05B 2219/45147 Machining blade, airfoil
• CPC Class Codes: Y10T 29/49325 Shaping integrally bladed rotor
• CPC Class Codes: Y10T 29/49336 Blade making
• CPC Class Codes: Y10T 29/49995 Shaping one-piece blank by removing material
• CPC Class Codes: Y10T 408/03 Processes
• CPC Class Codes: Y10T 409/303808 including infeeding

Abstract

A method of flank and/or point milling an integrally bladed rotor is conducted with an automatic tool path generator which generates a new created tool path including smooth transitions merging between an actual finished surface and a nominal surface of the integrally bladed rotor. The actual finished surface is presented in a mathematical transformation matrix which may be obtained in a 3-D scanning process.

Claims

1. A method of milling an integrally bladed rotor having a plurality of blades radially extending from a disc, the method comprising:

a) measuring the integrally bladed rotor in a 3-D scanning process and obtaining a 3-D mathematical transformation matrix of each finished surface of the integrally bladed rotor;

b) using the 3-D mathematical transformation matrix of the respective finished surfaces, a nominal computer aided design (CAD) model of respective surfaces of the integrally bladed rotor and nominal tool paths designed for the nominal CAD model of the respective surfaces, as calculation inputs to generate a new created tool path program, the new created tool path program including tool path transitions smoothly merging from the nominal CAD model of the respective surfaces to the 3-D mathematical transformation matrix of the respective finished surfaces, and the new created tool path program being defined taking into consideration, positions and orientations of a milling cutter having a selected geometry when controlled by the new created tool path program in a flank and point milling operation in order to prevent the milling cutter from interfering with blades adjacent a blade being currently machined; and

c) milling the integrally bladed rotor by using the milling cutter according to the new created tool path program in order to generate new finished surfaces of the integrally bladed rotor.

2. The method as defined in claim 1 wherein step (b) further comprises establishing a start point for calculation of the new created tool path program, by calculating the best fit with 6 degrees of liberty of the nominal tool paths within the respective finished surfaces of the integrally bladed rotor.

3. The method as defined in claim 1 wherein step (b) comprises providing the best fit of the 3-D mathematical transformation matrix of each finished surface of the integrally bladed rotor independently with the corresponding nominal surface in the nominal CAD model of the integrally bladed rotor to achieve minimum deviations between the nominal tool paths and the 3-D mathematical transformation matrix of each finished surface.

4. The method as defined in claim 1 wherein the new created tool path program comprises position adjustment of the milling cutter at various machining locations of the integrally bladed rotor with respect to positions of the milling cutter at corresponding locations in the nominal tool paths.

5. The method as defined in claim 4 wherein the new created tool path program comprises orientation adjustment of the milling cutter at said locations with respect to orientations of the milling cutter at corresponding locations in the nominal tool paths, in order to prevent the milling cutter from interfering with the adjacent blades.

6. The method as defined in claim 1 wherein the finished surface of the integrally bladed rotor comprises a suction side surface, pressure side surface, leading edge surface, trailing edge surface or root surface of each of the blades of the integrally bladed rotor.

7. The method as defined in claim 1 wherein the finished surface of the integrally bladed rotor comprises a machined surface or a forged surface.

8. The method as defined in claim 1 comprising concurrently generating the new created tool path program in a controller of a numerically controlled (N/C) machine tool in which the nominal tool paths are stored and milling an area of the integrally bladed rotor with the machine tool according to the new created tool path program, by sequentially generating and executing a succession of new move commands which replace a corresponding succession of nominal move commands of the nominal tool paths for this area.

9. A method of milling an integrally bladed rotor having a plurality of blades radially extending from a disc, the method comprising:

a) measuring the integrally bladed rotor in a 3-D scanning process and obtaining a 3-D mathematical transformation matrix of each finished surface of the integrally bladed rotor;

b) providing the best fit of the 3-D mathematical transformation matrix of each finished surface independently on a nominal computer aided design (CAD) model of the integrally bladed rotor;

c) using numerically controlled (N/C) nominal tool paths with the 3 D mathematical transformation matrix of each finished surface to achieve minimum deviations between the N/C nominal tool paths and the 3 D mathematical transformation matrix of each finished surface; and

d) generating N/C new created tool paths by gradually modifying the N/C nominal tool paths and milling an area of the integrally bladed rotor in accordance with the generated N/C new created tool paths, wherein the generated N/C new created tool paths include a smooth transition merging from the nominal CAD model to the 3-D mathematical transformation matrix of each finished surface, and wherein the new created tool paths prevent a milling cutter currently milling the area in accordance with the new created tool paths, from interfering with a blade spaced from and adjacent to the area.

10. The method as defined in claim 9 wherein the N/C new created tool paths comprise position adjustments of the milling cutter at various milling locations of the integrally bladed rotor with respect to positions of the milling cutter at corresponding locations in the N/C nominal tool paths.

11. The method as defined in claim 9 wherein the N/C new created tool paths comprise orientation adjustments of the milling cutter at various milling locations with respect to orientations of the milling cutter at corresponding locations in the N/C nominal tool paths, in order to prevent the milling cutter from interfering with the adjacent blade.

12. The method as defined in claim 9 wherein the generation of the N/C new created tool paths and the milling of the area of the integrally bladed rotor in accordance with the generated N/C new created tool paths, are concurrently conducted by sequentially generating and executing the succession of the modified move commands.