Displacement correcting device and method for a machine tool
AssigneeBrother Kogyo Kabushiki Kaisha
InventorShouki Yasuda
Life of this patent
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Abstract
The ratio of executed to skipped measurement movement commands required for actual measurement and a correction value when skipping a measurement movement command are determined and then updated according to past (hysteresis) measurement data. The actual thermal displacement measurement during an executed measurement movement command is performed at a proper rate to improve the machining efficiency of an NC machine tool and minimize an error due to the correction.
Claims27
A position data correction device of a machine tool, the device correcting position data based on a determined displacement of a tool of the machine tool from a predetermined origin position, the displacement determined in response to a measurement movement command, the position data correction device comprising:
- control means for selectively executing and skipping the measurement movement command;
- measurement means for measuring an actual displacement of the tool as the determined displacement in response to an executed measurement movement command;
- measurement hysteresis data storing means for storing measurement hysteresis data generated in response to executed measurement movement commands;
- determining means for determining, based on the measurement hysteresis data stored in the measurement hysteresis storage means, a skip count indicating a number of measurement movement commands to be skipped;
- and
- position correction means for correcting the position data of the machine tool based on the measurement hysteresis data stored in the measurement hysteresis data storage means and the determined skip count;
- wherein the control means selectively skips and executes the measurement movement commands based on the skip count.
A method for correcting position data based on a determined displacement of a tool of a machine tool from a predetermined origin position, comprising the steps of:
- inputting a current command for operating the machine tool;
- determining if the current command is a measurement movement command;
- comparing a skipped count of skipped measurement movement commands to a first comparison value;
- determining, when the current command is a measurement movement command, whether the current command is to be executed, based on results of the comparing step;
- if the current command is to be executed,
- performing a measurement movement operation to determine an actual displacement of the tool from the predetermined origin position,
- storing the actual displacement,
- resetting the skipped count to a second comparison value;
- and
- setting an updated displacement equal to the actual displacement;
- and
- correcting the position data based on the updated displacement.
A position data correction device of a machine tool, the position data correction device correcting position data based on a displacement of a tool of the machine tool from a predetermined origin position, the displacement being determined in response to a measurement movement command, the position data correction device comprising:
- a displacement measuring system, which measures an actual displacement in response to an executed measurement movement command;
- a measurement memory which stores measurement data generated in response to executed measurement movement commands;
- and
- a controller, comprising:
- a skip count system, which determines a skip count value for the number of subsequent measurement movement commands to be skipped in response to the executed measurement command and a skipped count value of the number of skipped measurement movement commands since a last executed measurement movement command,
- a selection system, which selectively executes and skips subsequent measurement movement commands based on the skip count value, and
- a position correction system, which corrects position data of the machine tool based on the measurement data stored in the measurement memory and the current skipped count value.
Dependencies are inferred from the claim text.