Method and apparatus for characterizing and enhancing the dynamic performance of machine tools
View Patent ↗Disclosed are various systems and methods for assessing and improving the capability of a machine tool. The disclosure applies to machine tools having at least one slide configured to move along a motion axis. Various patterns of dynamic excitation commands are employed to drive the one or more slides, typically involving repetitive short distance displacements. A quantification of a measurable merit of machine tool response to the one or more patterns of dynamic excitation commands is typically derived for the machine tool. Examples of measurable merits of machine tool performance include dynamic one axis positional accuracy of the machine tool, dynamic cross-axis stability of the machine tool, and dynamic multi-axis positional accuracy of the machine tool.
1. A method for assessing a dynamic performance of a machine tool having a first axis slide that has a first motion axis, comprising:
(a) electronically instructing the machine tool configured for machining a workpiece without rotation of the workpiece to drive the first axis slide along the first axis using a first pattern of dynamic excitation commands comprising displacements less than about one-half inch to generate a first machine-tool-response;
(b) deriving a first quantification of a measurable merit of machine tool performance from the first machine-tool-response to the first pattern of dynamic excitation commands;
(c) electronically instructing the machine tool to drive the first axis slide along the first motion axis using a second pattern of dynamic excitation commands comprising displacements less than about one-half inch, the second pattern being different from the first pattern of dynamic excitation commands to generate a second machine-tool-response; and
(d) deriving a second quantification of the measurable merit of machine tool performance from the second machine-tool-response to the second pattern of dynamic excitation commands.
2. The method of claim 1 wherein the measurable merit of machine tool performance comprises dynamic one axis positional accuracy of the machine tool, and wherein:
step (b) comprises
(i) measuring a first actual motion of the first axis slide along the first motion axis in response to the first pattern of dynamic excitation commands, and
(ii) comparing the first actual motion with the first pattern of dynamic excitation commands to establish a first quantification of the dynamic one axis positional accuracy of the machine tool.
3. The method of claim 2 wherein the measurable merit of machine tool performance comprises dynamic one axis positional accuracy of the machine tool and wherein step (d) comprises:
(i) measuring a second actual motion of the first axis slide along the first motion axis in response to the second pattern of dynamic excitation commands, and
(ii) comparing the second actual motion with the second pattern of dynamic excitation commands to establish a second quantification of the dynamic one axis positional accuracy of the machine tool.
4. A method for assessing a dynamic multi-axis positional accuracy of a machine tool having a first axis slide having a first motion axis and having a second axis slide having a second motion axis that is perpendicular to the first motion axis, comprising:
(a) electronically instructing the machine tool to drive the first axis slide along the first motion axis using a first pattern of dynamic excitation commands;
(b) while performing step (a), electronically instructing the machine tool to drive the second axis slide in a second pattern of dynamic excitation commands along the second motion axis,
(c) while performing steps (a) and (b), measuring a first actual motion of the first axis slide along the first motion axis,
(d) while performing steps (a) and (b), measuring a second actual motion of the second axis slide along the second motion axis,
(e) evaluating the dynamic multi-axis positional accuracy of the machine tool by comparing (1) a first ideal relationship between the first pattern of dynamic excitation commands and the second pattern of dynamic excitation commands with (2) the first actual motion of the first axis slide along the first motion axis and the second actual motion of the second axis slide along the second motion axis.
5. A method for assessing a dynamic performance of a machine tool having a first axis slide that has a first motion axis and a second axis slide having a second motion axis that is perpendicular to the first motion axis, comprising:
(a) electronically instructing the machine tool to drive the first axis slide along the first axis using a first pattern of dynamic excitation commands comprising displacements less than about one-half inch to generate a first machine-tool-response;
(b) deriving from the first machine-tool-response a first quantification of a measurable merit of machine tool performance indicating dynamic cross-axis stability of the machine tool comprising:
(i) measuring a first actual motion of the second axis slide along the second motion axis in response to the first pattern of dynamic excitation commands, and
(ii) comparing the first actual motion with an expected null response along the second motion axis to establish a first quantification of the dynamic cross-axis stability of the machine tool.
6. The method of claim 5 wherein the machine tool is configured for machining a workpiece without rotation of the workpiece.
7. A method for assessing a dynamic performance of a machine tool having a first axis slide that has a first motion axis and a second axis slide having a second motion axis that is perpendicular to the first motion axis, comprising:
(a) electronically instructing the machine tool to drive the first axis slide along the first axis using a first pattern of dynamic excitation commands comprising displacements less than about one-half inch to generate a first machine-tool-response;
(b) deriving from the first machine-tool-response a first quantification of a measurable merit of machine tool performance indicating dynamic cross-axis stability of the machine tool comprising:
(i) measuring a first actual motion of the second axis slide along the second motion axis in response to the first pattern of dynamic excitation commands,
(ii) comparing the first actual motion with an expected null response along the second motion axis to establish a first quantification of the dynamic cross-axis stability of the machine tool;
(c) electronically instructing the machine tool to drive the first axis slide along the first motion axis using a second pattern of dynamic excitation commands comprising displacements less than about one-half inch, the second pattern being different from the first pattern of dynamic excitation commands; and
(d) deriving a second quantification of the measurable merit of machine tool performance indicating dynamic cross-axis stability of the machine tool from the second pattern of dynamic excitation commands.
8. The method of claim 7 wherein the machine tool is configured for machining a workpiece without rotation of the workpiece.