Feed Axis Thermal Error Compensation with Adaptive Model Updating
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Solution Overview
Problem
Current thermal error compensation methods for feed axes in NC machine tools are not adaptive and fail to adjust to changes in thermal characteristics over time, leading to reduced machining accuracy and consistency due to wear, especially in complex tool trajectories and long-term machine tool use.
Innovation Solution
A self-adaptive compensation method using a laser interferometer and temperature sensor to test and establish a thermal error prediction model, identifying and adjusting parameters based on heat transfer mechanisms and pre-tightening conditions, allowing for real-time adaptive compensation of feed axis thermal errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed thermal error prediction model is used for compensation, then real-time compensation can be achieved without manual intervention, but the model cannot adapt to changes in thermal characteristics after long-term machine tool use, resulting in poor compensation accuracy
Solution Approach 1:
The patent transforms the static thermal error prediction model into a dynamic adaptive model. The model continuously updates its parameters (heat generation coefficient Q, heat transfer coefficient λ, convective heat dissipation coefficient h) based on real-time monitoring data from temperature sensors and laser interferometers, allowing it to adapt to changing thermal characteristics after long-term machine tool use while maintaining real-time compensation capability
Solution Approach 2:
The patent implements a feedback mechanism where the actual thermal error measured by the laser interferometer is compared with the predicted error from the model. The difference (residual error) is used to iteratively optimize the model parameters through least squares estimation, enabling the model to self-correct and adapt to actual thermal behavior changes over time
2Manufacturing precision
If workpiece accuracy measurement and manual tool compensation modification frequency are increased, then machining accuracy can be maintained, but processing efficiency is reduced and more operating strength is required
Solution Approach 1:
The patent enables the machine tool system to perform self-diagnosis and self-compensation of thermal errors. The automated system uses temperature sensors to monitor thermal states, the prediction model to calculate compensation values, and the NC system to automatically apply corrections to tool paths, eliminating the need for manual measurement and adjustment operations while maintaining high machining accuracy
Solution Approach 2:
The patent replaces manual mechanical measurement and adjustment operations with an automated optical-electronic system. The laser interferometer provides automated precision measurement, while the computer-based prediction model and NC system automatically calculate and apply compensation, substituting human operators with automated sensing, computing, and control systems
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
The method effectively maintains machining precision and stability by adaptively adjusting thermal parameters, reducing the influence of thermal errors on accuracy and consistency, and improving processing efficiency by minimizing the need for manual adjustments and workpiece measurement.
Implementation Method 1
a laser interferometer and a temperature sensor is used to perform a feed axis thermal error test
Implementation Method 2
a laser interferometer and a temperature sensor is used to perform a feed axis thermal error test
Implementation Method 3
The machine feed shaft of the nut screw drive system generates frictional heat, between the nut and the screw, during operation
Implementation Method 4
Such heat is transferred to the lead screw, causing its thermal expansion
Implementation Method 5
causing its thermal expansion
Implementation Method 6
the feed axis performs the heat engine movement, within a certain range at a certain feed rate, until the heat balance is established
Data Source
AI summary
A self-adaptive compensation method for feed axis thermal error, which belongs to the field of error compensation in NC machine tools. First, based on laser interferometer and temperature sensor, the feed axis thermal error test is carried out; following, the thermal error prediction model, based on the feed axis thermal error mechanism, is established and the thermal characteristic parameters in the model are identified, based on the thermal error test data; next, the parameter identification test is carried out, under the preload state of the nut; next, the adaptive prediction model is established, based on the thermal error prediction model, while the parameters in the measurement model are identified; finally, adaptive compensation of thermal errors is performed, based on the adaptive error prediction model, according to the generated feed axis heat.