Thermal Displacement Correction for Machine Tools

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing thermal displacement compensation methods for machine tools are unable to perform accurate real-time compensation due to the lengthy time required for finite element method structural analysis, leading to discrepancies between actual and inferred thermal displacement amounts.

Innovation Solution

A thermal displacement compensating device and method that uses temperature sensors to divide the machine tool's structural body into blocks with uniform temperature conditions, allowing for high-speed finite element method analysis and real-time compensation by calculating thermal displacement amounts at specific nodes, such as sliding surfaces and supporting reference positions, and using interpolation for accurate compensation values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a structural analysis by a finite element method is performed to infer thermal displacement amounts, then the accuracy of thermal displacement compensation is improved, but the time required for analysis becomes very long, making real-time compensation during machining impossible

Engineering Contradiction:

Improveaccuracy of thermal displacement compensationVSAvoidtime required for structural analysis

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent divides the structural body into multiple blocks with uniform temperature conditions within each block. This segmentation reduces the number of temperature variables from the total number of nodes to the number of blocks, significantly decreasing the calculation burden for thermal displacement analysis while maintaining sufficient accuracy for real-time compensation during machining operations

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the temperature parameter representation from node-level detailed temperatures to block-level uniform temperatures. By assuming uniform temperature within each block and using block temperatures as the basis for finite element analysis, the system reduces computational complexity and enables real-time thermal displacement compensation without sacrificing essential accuracy

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If temperature conditions at all nodes are used for finite element analysis, then the accuracy of thermal displacement inference is improved, but the quantity of calculations increases significantly, reducing calculation speed

Engineering Contradiction:

Improveaccuracy of thermal displacement inferenceVSAvoidcalculation speed for thermal displacement

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the structural body into blocks and assigns uniform temperature conditions to each block. This reduces the temperature vector size from the number of nodes to the number of blocks, dramatically decreasing the calculation quantity for thermal displacement vectors while maintaining the ability to infer thermal displacement accurately at critical locations

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by calculating thermal displacement vectors only at necessary nodes (such as sliding surfaces and supporting reference positions) rather than at all nodes. This selective approach reduces calculation quantity while ensuring sufficient accuracy for the specific compensation requirements of the machine tool

Inventive Principle:

Principle #16Partial or excessive action

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

Enables accurate real-time thermal displacement compensation by significantly reducing calculation time and improving the speed of finite element method analysis, ensuring precise compensation during machining.

Implementation Method 1

temperature sensors arranged at predetermined portions on a structural body of the machine tool

Methodology Applied

Scientific EffectTemperature detection:

Implementation Method 2

performs a structural analysis by a finite element method based on the temperatures of the respective blocks obtained by the block temperature obtaining means and that infers thermal displacement amounts of the structural body

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2711126B1Thermal displacement correction device and thermal displacement correction method

Publication Date: 2018.01.17 JTEKT CORP

Figure 1
Figure 2
Figure 3

AI summary

Provided are a thermal displacement compensating device and a thermal displacement compensating method for a machine tool, capable of performing a structural analysis by a finite element method at a high speed and hence, of performing a thermal displacement compensation accurately on a real time basis. A block temperature obtaining section obtains temperatures of respective blocks based on temperature information detected by temperature sensors wherein temperatures in each of the respective blocks into which a column is divided to be pluralized are defined as a uniform value. An FEM analysis section performs a structural analysis by a finite element method based on the temperatures of the respective blocks obtained by the block temperature obtaining section and infers thermal displacement amounts of the column. A compensation value calculation section calculates a compensation value for a machining command position based on the thermal displacement amounts of the column inferred by the finite element method analysis section. A compensation section compensates the machining command position by the compensation value obtained by the compensation value calculation section.