NUMERICAL CONTROLLER FOR CONTROLLING A FIVE-AXIS MACHINING APPARATUS

• US 20090140684A1
• Filed: 10/27/2008
• Published: 06/04/2009
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Yamaguchi, Takehiro, Otsuki, Toshiaki
• Granted Patent: US 7,969,111 B2
• Time in Patent Office: Days
• US Class Current: 318/572
• CPC Class Codes: G05B 19/404 characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia G05B19/19, G05B19/41 take precedence
• CPC Class Codes: G05B 2219/49344 Surface, 5-axis surface machining
• CPC Class Codes: G05B 2219/50297 Compensation of positioning error due to a-axis, b-axis tool rotation

Abstract

A numerical controller capable of moving a tool end point position to an accurate position in a five-axis machining apparatus. Compensation amounts are set, which correspond to respective ones of a linear axis-dependent translational error, a rotary axis-dependent translational error, a linear axis-dependent rotational error, and a rotary axis-dependent rotational error, which are produced in the five-axis machining apparatus. A translational/rotational compensation amount Δ3D is determined from these compensation amounts and added to a command linear axis position Pm. As the compensation amounts, there is used a corresponding one of six-dimensional lattice point compensation vectors, which are determined in advance as errors due to the use of a mechanical system and measured at lattice points of lattices into which the entire machine movable region is divided.

Claims

1. A numerical controller for controlling a five-axis machining apparatus provided with three linear axes and two rotary axes for moving a tool relative to a workpiece mounted on a table, according to commands of a machining program, said numerical controller comprising:

axis-dependent compensation amount calculating means that calculates an axis-dependent translational compensation amount and an axis-dependent rotational compensation amount for a command axis position;

translational/rotational compensation amount calculating means that calculates a translational/rotational compensation amount based on the axis-dependent translational compensation amount and the axis-dependent rotational compensation amount;

compensation amount adding means that adds the calculated translational/rotational compensation amount to a command linear-axis position to obtain a compensated linear-axis position; and

means that drives the three linear axes to the compensated linear-axis position and drives the two rotary axes to command positions.

2. A numerical controller according to claim 1, wherein said axis-dependent compensation amount calculating means calculates a rotary axis-dependent translational compensation amount and a rotary axis-dependent rotational compensation amount for a command rotary-axis position, and said translational/rotational compensation amount calculating means calculates the translational/rotational compensation amount based on the rotary axis-dependent translational compensation amount and the rotary axis-dependent rotational compensation amount.

3. A numerical controller according to claim 1, wherein said axis-dependent compensation amount calculating means calculates a linear axis-dependent translational compensation amount and a linear axis-dependent rotational compensation amount for a command linear-axis position, and said translational/rotational compensation amount calculating means calculates the translational/rotational compensation amount based on the linear axis-dependent translational compensation amount and the linear axis-dependent rotational compensation amount.

4. A numerical controller according to claim 1, wherein said axis-dependent compensation amount calculating means calculates a linear axis-dependent translational compensation amount and a linear axis-dependent rotational compensation amount for a command linear-axis position, and a rotary axis-dependent translational compensation amount and a rotary axis-dependent rotational compensation amount for a command rotary-axis position, and said translational/rotational compensation amount calculating means calculates the translational/rotational compensation amount based on the linear axis-dependent translational compensation amount, the linear axis-dependent rotational compensation amount, the rotary axis-dependent translational compensation amount and the rotary axis-dependent rotational compensation amount.

5. A numerical controller according to claim 1, wherein the two rotary axes are provided for rotating a machining head which supports the tool in the five-axis machining apparatus, and the translational/rotational compensation amount is calculated based on translational/rotational transformation of a tool length compensation vector.

6. A numerical controller according to claim 1, wherein the two rotary axes are provided for rotating the table on which the workpiece is mounted in the five-axis machining apparatus, and the translational/rotational compensation amount is calculated based on translational/rotational transformation of a vector extending from a rotation center of the table to an end point of the tool.

7. A numerical controller according to claim 1, wherein the two rotary axes comprises a first rotary axis for rotating a machining head which supports the tool, and a second rotary axis for rotating the table on which the workpiece is mounted, and the translational/rotational compensation amount is calculated based on translational/rotational transformation of a tool length compensation vector and translational/rotational transformation of a vector extending from a rotation center of the table to an end point of the tool.

8. A numerical controller according to claim 1, wherein said linear axis-dependent compensation amount calculating means divides a three-dimensional coordinate system space defined by the three linear axes into lattice regions arranged at predetermined intervals in respective axis directions, stores a lattice point compensation vector indicative of a rotational compensation amount and a translational compensation amount at each lattice point of the lattice regions, and calculates a linear axis-dependent rotational compensation amount and a linear axis-dependent translational compensation amount at a position on the three linear axes based on lattice point compensation vectors.

9. A numerical controller according to claim 8, wherein the lattice point compensation vectors are determined based on actually measured positions and theoretical positions of measurement points using test bars or ball end mills having different lengths from each other.

10. A numerical controller according to claim 1, wherein said rotary axis-dependent compensation amount calculating means divides a two-dimensional coordinate system space defined by the two rotary axes into lattice regions arranged at predetermined intervals in respective axis directions, stores a lattice point compensation vector indicative of a rotational compensation amount and a translational compensation amount at each lattice point of the lattice regions, and calculates a rotary axis-dependent rotational compensation amount and a rotary axis-dependent translational compensation amount at a position on the two rotary axes based on the lattice point compensation vectors.

11. A numerical controller according to claim 10, wherein the lattice point compensation vectors are determined based on actually measured positions and theoretical positions of measurement points using test bars or ball end mills having different lengths from each other.

12. A numerical controller according to claim 1, wherein said rotary axis-dependent compensation amount calculating means divides a one-dimensional coordinate system space defined by one of the two rotary axes at predetermined intervals, stores a division point compensation vector indicative of a rotational compensation amount and a translational compensation amount at each of division points arranged at the predetermined intervals, divides a one-dimensional coordinate system space defined by another of the two rotary axes at predetermined intervals, stores a division point compensation vector indicative of a rotational compensation amount and a translational compensation amount at each of division points arranged at the predetermined intervals, and calculates rotary axis-dependent compensation amounts at respective positions on the two rotary axes based on the division point compensation vectors.

13. A numerical controller according to claim 12, wherein the division point compensation vectors are determined based on actually measured positions and theoretical positions of measurement points using test bars or ball end mills having different lengths from each other.

14. A numerical controller according to claim 1, wherein said linear axis-dependent compensation amount calculating means divides a two-dimensional coordinate system space defined by two of said three linear axes into lattice regions arranged at predetermined intervals in respective axis directions, stores a lattice point compensation vector indicative of a rotational compensation amount and a translational compensation amount at each lattice point of the lattice regions, calculates a linear axis-dependent rotational compensation amount and a linear axis-dependent translational compensation amounts at a position on the two linear axes based on the lattice point compensation vectors, divides a one-dimensional coordinate system space defined by a remaining one of the three linear axes at predetermined intervals, stores a division point compensation vector indicative of a rotational compensation amount and a translational compensation amount at each of division points arranged at the predetermined intervals, and calculates a linear axis-dependent rotational compensation amount and a linear axis-dependent translational compensation amount at a position on the remaining one of the three linear axes based on the division point compensation vectors.

15. A numerical controller according to claim 14, wherein the lattice point compensation vectors and the division point compensation vectors are determined based on actually measured positions and theoretical positions of measurement points using test bars or ball end mills having different lengths from each other.

16. A numerical controller according to claim 1, wherein said linear axis-dependent compensation amount calculating means divides each of one-dimensional coordinate system spaces defined by respective ones of the three linear axes at predetermined intervals, stores a division point compensation vector indicative of a rotational compensation amount and a translational compensation amount at each of division points arranged at the predetermined intervals, and calculates linear axis-dependent compensation amounts at positions on the respective ones of the three linear axes based on the division point compensation vectors.

17. A numerical controller according to claim 16, wherein the division point compensation vectors are determined based on actually measured positions and theoretical positions of measurement points using test bars or ball end mills having different lengths from each other.

18. A numerical controller according to claim 1, wherein the command axis position is an interpolated one of an axis position of the three linear axes or an axis position of the two rotary axes respectively commanded by the machining program.

19. A numerical controller according to claim 1, wherein the command axis position is an axis position of the three linear axes or an axis position of the two rotary axes respectively commanded by the machining program.