Thermal Displacement Compensation for Machine Tools
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Solution Overview
Problem
Existing thermal displacement compensation methods for machine tools are inadequate in accurately adjusting compensation amounts across different thermal states (heat generating, steady, and heat dissipating states), leading to compensation errors and increased costs due to the use of sensors.
Innovation Solution
A thermal displacement compensating device that calculates thermal displacement amounts and adjusts compensation based on identified states without using sensors, employing a thermal displacement state identification unit and coefficient calculation unit to determine the appropriate coefficients for precise compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is used to detect thermal displacement, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the temperature sensor-based thermal displacement detection system with a mechanical measurement system using a laser interferometer. The interferometer directly measures the actual position of the measurement point on the machine tool, providing thermal displacement information without requiring temperature sensors or complex thermal modeling.
Solution Approach 2:
The patent introduces a laser interferometer as an intermediary measurement device that indirectly captures thermal displacement effects by measuring position changes. This intermediary approach allows thermal displacement to be measured through optical interference patterns rather than direct temperature sensing, simplifying the overall system.
2Device complexity
If thermal displacement compensation is performed without considering thermal states, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent dynamically adjusts the compensation amount based on the identified thermal state (heat generating, steady, or heat dissipating). The control unit selects different compensation coefficients corresponding to different thermal states, allowing the compensation system to adapt to changing thermal conditions without requiring complex real-time thermal modeling or multiple sensors.
Solution Approach 2:
The patent changes the compensation parameter (compensation coefficient) based on the thermal state. By identifying whether the machine tool is in a heat generating state, steady state, or heat dissipating state, the system selects appropriate compensation coefficients to optimize thermal displacement compensation for each thermal condition.
3Ease of operation
If compensation coefficient is fixed, then ease of operation is improved, but manufacturing precision deteriorates under varying thermal conditions
Solution Approach 1:
The patent makes the compensation coefficient dynamic by selecting from multiple predetermined coefficients based on the identified thermal state. The control unit automatically switches between different compensation coefficients (first coefficient for heat generating state, second coefficient for steady state, third coefficient for heat dissipating state) without requiring manual intervention, maintaining ease of operation while improving precision.
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 allows for precise thermal displacement compensation across various states without additional cost, enhancing precision and reliability by eliminating the need for sensors and improving compensation accuracy.
Implementation Method 1
a laser interferometer; an actual position of the measurement point is measured
Implementation Method 2
thermal displacement amount calculation unit that calculates a thermal displacement amount that is generated by heat generation or dissipation as the machine tool is actuated or stopped
Data Source
AI summary
A thermal displacement compensating device calculates a thermal displacement amount which is produced by heat generation or dissipation as a machine tool is actuated or stopped and changes with time. A thermal displacement compensation amount is calculated by multiplying the calculated thermal displacement amount by a coefficient. A position command is compensated by adding the thermal displacement compensation amount to the position command. On the other hand, a variation between a thermal displacement amount calculated last time and a current thermal displacement amount is determined for each predetermined time. A plurality of thermal displacement amount change states are identified based on comparison between the determined variation and a predetermined threshold. The coefficient is calculated based on the identified thermal displacement amount change state.