Machine Tool Thermal Displacement Correction via Variable Coefficients
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Solution Overview
Problem
Existing thermal displacement correction systems for machine tools are inefficient and require reconfiguration in different installation environments, leading to decreased efficiency and increased costs due to uncertainty in correction accuracy.
Innovation Solution
A method and system that utilizes a measurement reference, position measurement device, and thermometer to measure temperature and position changes in the installation environment, calculating predicted thermal displacement amounts by integrating temperature changes with variable coefficients to optimize correction parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal displacement correction system is set during production in a different environment from installation environment, then the correction system can be initially configured, but the correction accuracy deteriorates due to environmental differences
Solution Approach 1:
The patent applies preliminary action by pre-setting multiple candidate correction parameters during production before the machine tool is installed. These parameters are prepared in advance based on production environment data, and the optimal parameter is selected after installation based on actual performance in the installation environment, thus resolving the contradiction between early configuration and eventual accuracy.
Solution Approach 2:
The patent changes parameters by using multiple candidate correction parameters with different coefficient of variation values instead of a single fixed parameter. This allows the system to adapt to different installation environments by selecting the most appropriate parameter set, thereby maintaining both ease of initial setup and high correction accuracy.
2Measurement precision
If thermal displacement correction system is reconfigured in installation environment, then correction accuracy is improved, but productivity deteriorates due to additional setup time and cost
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing multiple candidate correction parameters during production. This eliminates the need for time-consuming reconfiguration at the installation site, as the optimal parameter can be directly selected from pre-prepared options, thus improving both accuracy and productivity.
Solution Approach 2:
The patent creates copies of correction parameters for different environmental conditions. Instead of reconfiguring the entire correction system at installation, the system copies and selects from pre-existing parameter sets that were generated during production, significantly reducing setup time and cost while maintaining accuracy.
3Device complexity
If coefficient of variation is set as constant, then calculation is simplified, but measurement precision of thermal displacement correction deteriorates
Solution Approach 1:
The patent applies dynamics by changing the coefficient of variation from a constant to a variable that can take multiple discrete values. This allows the correction calculation to adapt to different thermal conditions while maintaining manageable complexity through the use of pre-defined candidate values rather than continuous optimization.
Solution Approach 2:
The patent changes the parameter nature of the coefficient of variation from fixed to variable. By introducing multiple candidate values for the coefficient of variation, the system achieves higher correction accuracy without excessive complexity, as the variable parameter is selected from a finite set of pre-determined options.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and efficient thermal displacement correction by identifying optimal coefficients of variation, minimizing thermal displacement effects, and improving machining accuracy without reliance on trial and error.
Implementation Method 1
a value obtained by integrating a temperature change amount corresponds to a thermal displacement amount of a position of the measurement reference
Data Source
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AI summary
A thermal displacement correction method includes providing a calibration ball (44) affixed to a table (18), a probe (28) for measuring a position of the calibration ball (44), and thermometers (48a to 48d), setting a fixed coefficient in which a value obtained by integrating a temperature change amount corresponds to a thermal displacement of a position of the calibration ball (44), and a coefficient of variation to be multiplied by the fixed coefficient for weighting, simultaneously performing measurement of a position of the calibration ball (44) and the temperature change amount a plurality of repetitions during one period in which a temperature changes, calculating a plurality of predicted thermal displacement amounts Z by multiplying the product of the measured temperature change amount and the fixed coefficient by the plurality of coefficients of variation, identifying one coefficient of variation for which a difference of a change amount of the position of the calibration ball (44) in the one period is minimum from among the plurality of predicted thermal displacement amounts, and performing thermal displacement correction based on the predicted thermal displacement amount Z calculated from the fixed coefficient, the temperature change amount, and the identified coefficient of variation.