Machine Tool Thermal Displacement Estimation During Cooling Transients
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Solution Overview
Problem
Existing methods for estimating thermal displacement in machine tools, such as machining centers, face challenges in accurately estimating thermal displacement during transient states of cooling device operation, leading to increased power consumption and potential machining accuracy deterioration.
Innovation Solution
A thermal displacement estimating method that involves detecting temperatures using a temperature measurement device and applying an estimation model to calculate coefficients related to time response and cooling capacity changes, incorporating conversion and cooling heat amount equivalent temperature change amounts to accurately estimate thermal displacement, even during changes in cooling device operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the main spindle cooling device is stopped to reduce power consumption, then power consumption is reduced, but thermal displacement increases over time deteriorating machining accuracy
Solution Approach 1:
The system continuously monitors the actual thermal displacement of the main spindle and feeds this information back to the control device. The control device compares the actual thermal displacement with the estimated thermal displacement, and when the absolute value of the difference exceeds a predetermined threshold, it determines that the cooling device should be operated to maintain machining accuracy while minimizing power consumption.
Solution Approach 2:
The system dynamically changes the operational parameters of the cooling device based on real-time thermal displacement measurements. By adjusting the cooling device operation state according to the actual thermal displacement and its rate of change, the system optimizes the balance between power consumption and machining accuracy maintenance.
2Manufacturing precision
If the main spindle cooling device is operated continuously to maintain machining accuracy, then machining accuracy is maintained, but power consumption increases
Solution Approach 1:
The system transitions from static continuous operation or simple on-off control to dynamic adaptive control. The control device dynamically adjusts the cooling device operation state based on real-time thermal displacement measurements and their rate of change, allowing the system to respond flexibly to actual thermal conditions and optimize power consumption while maintaining accuracy.
Solution Approach 2:
The system uses estimated thermal displacement calculated from rotation speed and time to predict future thermal displacement trends. By comparing the estimated thermal displacement with actual measurements and determining the rate of change, the system takes preliminary action to operate the cooling device before thermal displacement exceeds acceptable thresholds, preventing accuracy deterioration while avoiding unnecessary continuous operation.
3Device complexity
If thermal displacement is estimated using a fixed calculation coefficient, then the estimation method is simple, but estimation accuracy deteriorates in transient states when cooling device operation changes
Solution Approach 1:
The system performs preliminary calculation of the rate of change of thermal displacement using estimated thermal displacement values derived from rotation speed and time. This preliminary calculation allows the system to anticipate thermal displacement trends before actual measurements are taken, enabling more accurate estimation during transient states when cooling device operation changes, without significantly increasing system complexity.
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 method allows for accurate thermal displacement estimation in transient states, reducing power consumption without compromising machining accuracy by adjusting cooling capacity based on temperature thresholds, thereby improving estimation accuracy and power management.
Implementation Method 1
detecting each temperature of a predetermined heat generating portion and a predetermined main body structure portion by the temperature measurement device
Implementation Method 2
there is a method of removing heat (hereinafter referred to as 'main spindle cooling') by disposing a cooling circuit in a main spindle housing portion and flowing a cooling oil
Implementation Method 3
a thermal displacement in an axial direction is generated due to frictional heat generation in a bearing and heat generation in a motor during rotation of a main spindle
Implementation Method 4
a thermal displacement in an axial direction is generated due to frictional heat generation in a bearing and heat generation in a motor during rotation of a main spindle
Implementation Method 5
a thermal displacement in an axial direction is generated due to frictional heat generation in a bearing and heat generation in a motor during rotation of a main spindle
Data Source
AI summary
A thermal displacement estimating method includes: detecting each temperature of a predetermined heat generating portion and a predetermined main body structure portion by a temperature measurement device; and estimating a thermal displacement of the heat generating portion by an estimation model based on a detected temperature. The estimating of the thermal displacement includes: obtaining a conversion coefficient equivalent temperature change amount equivalent to a change amount of a conversion coefficient before and after a cooling capacity change from a relationship between a predetermined cooling heat amount of a cooling device and the conversion coefficient between the temperature and the displacement for estimating the thermal displacement from the detected temperature and/or a cooling heat amount equivalent temperature change amount equivalent to a changed heat amount before and after the cooling capacity change from a relationship between the predetermined cooling heat amount and a temperature equivalent to the cooling heat amount.