Machine Tool Thermal Displacement Correction via Temperature Simulation
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Solution Overview
Problem
Existing methods for estimating temperatures in machine tools where direct measurement is difficult, such as in rotary portions or when using coolants, lead to inaccuracies in thermal displacement correction, especially during rapid temperature changes, and require extensive experimental data and labor-intensive design adjustments.
Innovation Solution
A method involving temperature estimation using temperature sensors attached to other portions, operation information represented by ON/OFF states, and coefficient determination based on time constants to accurately estimate temperatures in hard-to-measure areas, considering coolant usage and heat of vaporization effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are attached to components of the machine tool structure, then thermal displacement correction can be performed, but measurement is difficult in many portions due to restriction by wiring and the like
Solution Approach 1:
The patent uses temperature simulation blocks as simplified copies of the actual machine tool components (turret head, spindle, etc.). These simulation blocks replicate the thermal characteristics of the target components without requiring complex wiring, allowing temperature measurement in locations that would otherwise be inaccessible or difficult to instrument directly.
Solution Approach 2:
The temperature simulation blocks act as intermediary elements between the coolant system and the actual machine tool components. By placing these blocks in the coolant flow path, the system indirectly measures the thermal state of components that would be difficult to measure directly, eliminating the need for complex wiring in rotary portions and other hard-to-reach areas.
2Ease of operation
If correction is performed according to a temperature of a portion of which the temperature is easily measured, then ease of operation is improved, but accuracy for estimating thermal displacement is reduced
Solution Approach 1:
The temperature simulation blocks are designed to replicate the thermal characteristics of the actual machine tool components they represent. By copying the heat capacity and thermal response characteristics, the simulation blocks provide temperature readings that accurately reflect the thermal state of the target components (turret head, spindle, etc.), thereby maintaining estimation accuracy while improving measurement accessibility.
3Measurement precision
If a temperature simulation block is provided in a turret head and the temperature is indirectly measured by using the temperature simulation block, then thermal displacement can be accurately estimated, but the method is performed on the assumption that machining is performed with the use of a coolant
Solution Approach 1:
The patent dynamically adjusts the temperature estimation method based on coolant usage conditions. When coolant is not used, the system switches to using the temperatures of the machine tool structure components directly. This dynamic adaptation allows the system to maintain accurate thermal displacement estimation across different machining conditions, whether coolant is applied or not.
4Adaptability or versatility
If coefficients are used so as to be different between a case where a coolant is used and a case where no coolant is used, then adaptability is improved, but it requires extensive experimental data and labor-intensive design adjustments
Solution Approach 1:
The temperature simulation blocks provide a universal solution that works across different coolant conditions without requiring extensive experimental calibration. The simulation blocks naturally adapt to the thermal environment, and the system uses simple switching logic based on coolant presence, eliminating the need for complex coefficient adjustments and reducing design effort.
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 approach allows for accurate and simple temperature estimation and thermal displacement correction, enhancing machining accuracy by smoothly changing estimated temperatures and reducing correction errors, even during transient states and coolant changes.
Implementation Method 1
temperature sensors are attached to the components of the structure of the machine tool, a displacement is calculated on the basis of the measured temperatures
Implementation Method 2
a coolant which has not yet been ejected is brought into thermal contact with the temperature simulation block
Implementation Method 3
large displacement occurs, in some cases, due to rapid temperature change caused by difference in temperature between the coolant and the workpiece or a structure
Implementation Method 4
in a case where the discharging of the coolant is stopped, rapid temperature change occurs due to heat of vaporization generated by vaporization of water from the surface of the workpiece or the structure
Data Source
AI summary
A temperature of a portion of which the temperature is difficult to directly measure is accurately estimated in a simple method.In S1, information about a coolant discharging/stopping state is obtained. As the information about the coolant discharging/stopping state, a flag is used such that the flag represents 1 for the discharging state and the flag represents 0 for the stopping state. Next, in S2, temperature data is obtained from temperature sensors provided in components of a machine tool, a machining space, and a coolant tank. Next, in S3, lag process is performed for the coolant discharging/stopping state flag, and coefficients for measured temperatures of the coolant and the structure are calculated. Next, in S4, the measured temperatures are multiplied by the coefficients, and an estimated temperature of a portion to which the temperature sensor is not attached is calculated.