Method of calibrating a machine having at least two rotation axes

Patent metadata

Field	Value
Publication number	US-11487268-B2
Application number	US-201916521710-A
Country	US
Kind code	B2
Filing date	Jul 25, 2019
Priority date	Jul 25, 2019
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

The method can include measuring the tridimensional positions of a reference feature for a first at least three different angular positions of the reference feature around the first rotation axis and a same first reference angular position around the second rotation axis, the reference feature being fixed relative to the component; and measuring the tridimensional positions of the reference feature for a second at least three different angular positions of the reference feature around the first rotation axis and a same second reference angular position around the second rotation axis.

First claim

The invention claimed is:

1. A method of manufacturing a part with a machine having a component rotatable around a first rotation axis, the component pivotable about a second rotation axis by moving the component along an arc-shaped cradle, the method comprising:
measuring a first set of 3-dimensional positions of a reference feature for at least three angular positions of the reference feature around the first rotation axis and a first reference angular position around the second rotation axis, the reference feature fixed relative to the component;
determining a first coordinate system of the component at the first reference angular position by determining a position and orientation of the first rotation axis in the first reference angular position and calibrating a reference coordinate system of the machine based on the first coordinate system for operating the machine with the component at the first reference angular position;
machining a first feature in the part when the part is at the first reference angular position by using the first coordinate system;
pivoting the component about the second rotation axis by moving the component along the arc-shaped cradle from the first reference angular position to a second reference angular position, a pivot point defined at an intersection between the first rotation axis and the second rotation axis, the pivot point being axially offset from the component relative to the first rotation axis;
measuring a second set of 3-dimensional positions of the reference feature for at least three angular positions of the reference feature around the first rotation axis and the second reference angular position around the second rotation axis;
determining a second coordinate system of the component at the second reference angular position by determining a position and orientation of the first rotation axis in the second reference angular position and calibrating the reference coordinate system of the machine based on the second coordinate system for operating the machine with the component at the second reference angular position, the calibrating of the reference coordinate system of the machine based on the second coordinate system includes computing a difference between the first coordinate system and the second coordinate system; and
machining a second feature in the part when the part is at the second reference angular position by using the computed difference, the machining of the second feature including transforming instruction coordinates of a tool of the machine using the computed difference.

2. The method of claim 1 wherein the first coordinate system and the second coordinate system both include a determined position and orientation of the first rotation axis in a reference coordinate system of the machine.

3. The method of claim 2 further comprising determining a reference point along the determined position and orientation of the first rotation axis for both the first coordinate system and the second coordinate system, the reference points being determined as a point closest to the determined position and orientation of the first rotation axis in the other coordinate system.

4. The method of claim 3 further comprising, defining the reference points as pivot points of the rotation axes.

5. The method of claim 4 further comprising, using establishing a displacement matrix matching every point in the first coordinate system to a corresponding point in the second coordinate system based on the difference between the first coordinate system and the second coordinate system.

6. The method of claim 1 wherein the component is a part holder.

7. The method of claim 1 wherein the measuring is performed with a touch probe handled by a tool holder of the machine.

8. The method of claim 7 wherein the measuring includes controlling the movement of the tool holder.

9. The method of claim 8 wherein the control of the movement of the tool holder during the measurements taken at the second reference angular position is based on a mathematical rotation of the first coordinate system around a theoretical position of the second rotation axis by an angle equivalent to the difference between the first reference angular position and the second reference angular position.

10. The method of claim 1 wherein the first coordinate system and the second coordinate system both include at least an arc fitting the corresponding three angular positions, an axis normal to the arc and intersecting a center of the arc, and a reference position along the length of the axis relative to the center of the arc.

11. The method of claim 10 wherein the position along the length of the axis corresponds to a theoretical position of the second rotation axis.

12. The method of claim 10 wherein the reference position along the length of the axis corresponds to a point closest to the axis of the other coordinate system.

13. The method of claim 1 wherein the component is further rotatable around a third rotation axis, wherein the steps of measuring are performed at a first reference angular position around the third rotation axis, and repeated for at least a second reference angular position around the third rotation axis, the steps of determining are performed for the first reference angular position around the third rotation axis, and repeated for the second reference angular position around the third rotation axis.

14. A computer implemented method of operating a CNC machine having a component rotatable around a first rotation axis, the component pivotable about a second rotation axis by moving the component along an arc-shaped cradle, the method comprising:
measuring a first set of 3-dimensional positions of a reference feature for at least three different angular positions of the reference feature around the first rotation axis and a first reference angular position around the second rotation axis, the reference feature being fixed relative to the component;
pivoting the component about the second rotation axis by moving the component along the arc-shaped cradle from the first reference angular position to a second reference angular position, a pivot point defined at an intersection between the first rotation axis and the second rotation axis, the pivot point being axially offset from the component relative to the first rotation axis;
measuring a second set of 3-dimensional positions of the reference feature for at least three different angular positions of the reference feature around the first rotation axis and the second reference angular position around the second rotation axis;
based on the measured first and second sets of 3-dimensional positions:
determining a first coordinate system of the component at the first reference angular position around the second rotation axis;
determining a second coordinate system of the component at the second reference angular position around the second rotation axis;
computing a difference between the first coordinate system and the second coordinate system;
operating the CNC machine at the first reference angular position based on the first coordinate system;
and operating the CNC machine at the second reference angular position based on the second coordinate system by transforming instruction coordinates of a tool of the machine using the computed difference.

15. The method of claim 14 wherein the component is a part holder, and operating the CNC machine includes moving a tool holder relative to the part holder.

16. The method of claim 14 wherein operating the CNC machine based on the second coordinate system includes determining the differen

Assignees

• Pratt & Whitney Canada

Inventors

• Blais Mario
• Laberge Clement Drouin
• Ing Visal

Classifications

• G05B2219/50022

  Null point on tool relative to null point of toolholder, rotationcenter · CPC title

• G05B2219/40596

  Encoder in each joint · CPC title

• G05B2219/33099

  Computer numerical control [CNC]; Software control [SWC] · CPC title

• G05B2219/30

  Nc systems · CPC title

• G05B2219/41092

  References, calibration positions for correction of value position counter · CPC title