Machine Tool Thermal Displacement Correction with Re-detection
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Solution Overview
Problem
Existing thermal displacement correction methods for machine tools face challenges in achieving high accuracy and reliability due to improper detection by position sensors, especially when chips are caught or coolant splashes occur, leading to incorrect correction factors and reduced machining precision.
Innovation Solution
A thermal displacement correction device that includes a position detection unit, a re-detection unit, and a correction error calculation unit to determine correct detection, perform re-detection if necessary, and modify the thermal displacement correction amount based on accurate measurements, considering changes in ambient temperature and other thermal displacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position detection is performed continuously to improve measurement accuracy, then detection reliability deteriorates due to chip interference and coolant splash
Solution Approach 1:
The system performs position detection periodically at specific intervals rather than continuously, using a detection determination unit to decide whether detection is necessary based on machining state changes. This reduces the frequency of detection operations, minimizing the impact of chip interference and coolant splash on detection reliability while maintaining adequate measurement accuracy through targeted detection at critical moments.
Solution Approach 2:
The system incorporates a detection determination unit that uses feedback from machining state monitoring to decide whether position detection should be performed. By analyzing changes in machining conditions (such as feed rate changes, tool changes, or position corrections), the system intelligently determines when detection is necessary, improving reliability by avoiding detection during unfavorable conditions while maintaining measurement precision when needed.
2Productivity
If thermal displacement correction is applied in real-time to improve productivity, then manufacturing precision deteriorates due to inaccurate detection data
Solution Approach 1:
The system performs position detection and correction amount calculation in advance before actual machining operations begin. By detecting the initial position and calculating thermal displacement corrections beforehand, the system ensures accurate baseline data is available while maintaining productivity during the actual machining process. This preliminary action allows the correction values to be applied consistently without compromising either speed or precision.
Solution Approach 2:
The system dynamically adjusts the detection and correction process based on actual machining conditions. When machining state changes are detected (such as feed rate changes or tool changes), the system triggers additional detection and recalculation of correction amounts. This dynamic approach ensures that correction data remains accurate and up-to-date throughout the machining process, maintaining manufacturing precision while adapting to changing productivity requirements.
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
This solution ensures accurate thermal displacement correction by re-detecting positions and modifying correction amounts, reducing false detection and improving machining precision even with large thermal displacements, thereby enhancing the overall accuracy and reliability of machine tool operations.
Implementation Method 1
Since a feed screw and a spindle of a machine tool are driven by a motor, they are expanded so that their mechanical positions change due to heating of the motor, frictional heat generated by the rotation of a bearing, and frictional heat from a contact portion between a ball screw and a ball nut of the feed screw.
Implementation Method 2
a position detection unit configured to detect a position of a movable part of the machine tool
Data Source
AI summary
A thermal displacement correction device for a machine tool is provided with detection result determination unit configured to determine, based on an actual position and a reference position detected by position detection unit, whether or not the actual position is based on correct detection, correction error calculation unit configured to calculate a correction error in the actual position if it is determined that the result of detection is based on correct detection, and correction amount modification unit configured to modify a thermal displacement correction amount based on the correction error.