Wire EDM Thermal Displacement Correction via Self-Diagnosis

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Solution Overview

Problem

Existing wire electrical discharge machines face challenges in accurately correcting for thermal displacement due to varying temperature environments, requiring complex and user-specific correction values that are difficult to set without precise measurement instruments and sensors.

Innovation Solution

A wire electrical discharge machine with a temperature detection unit, storage units, and calculation units that detect mechanical and machining fluid temperatures, calculate actual position corrections, and adjust drive shaft movements to correct for thermal displacement, allowing for automatic setup of suitable correction values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If thermal displacement correction values are preset for different temperature environments, then machining accuracy is improved, but device complexity and setup difficulty increase due to requiring precise measurement instruments and sensors

Engineering Contradiction:
Improvemachining accuracyVSAvoidcorrection value setup complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The wire electrical discharge machine performs self-diagnosis by automatically detecting its own thermal displacement using built-in position detectors and temperature sensors. The system autonomously calculates correction values by comparing commanded positions with actual positions during automatic operation, eliminating the need for external measurement instruments and complex manual setup procedures

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system continuously monitors the actual position of mechanical sections during automatic operation and compares it with the commanded position. Based on this feedback and temperature data, the system automatically calculates and applies correction values to compensate for thermal displacement, enabling dynamic adaptation without manual intervention

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If thermal displacement correction is implemented using preset values, then machining accuracy is improved, but ease of operation deteriorates due to difficulty in setting correction values

Engineering Contradiction:
Improvemachining accuracyVSAvoidcorrection value setting ease
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The machine automatically performs thermal displacement correction by detecting its own position deviations during normal operation and autonomously calculating appropriate correction values. This self-service capability eliminates the need for operators to manually set complex correction values, significantly improving ease of operation while maintaining high machining accuracy

Inventive Principle:
Principle #25Self-service

3Manufacturing precision

If temperature control facilities are used to maintain constant machine temperature, then thermal displacement is reduced, but investment cost and operating cost increase significantly

Engineering Contradiction:
Improvemachining accuracyVSAvoidtemperature control cost
Core Design Contradiction:
Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

Instead of controlling temperature to prevent thermal displacement, the system changes the approach by detecting actual thermal displacement through position detectors and sensors, then dynamically adjusting correction values based on temperature variations. This allows the machine to operate effectively without expensive temperature control facilities while maintaining high machining accuracy

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system converts the harmful effect of thermal displacement into useful information by using position detectors and temperature sensors to measure the displacement. These measurements are then used to calculate correction values that compensate for the thermal effects, transforming the problem of thermal expansion into a basis for automatic correction without requiring temperature control

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 easy and accurate setup of thermal displacement correction values specific to each machine's environment, improving machining accuracy without the need for additional measurement instruments or sensors.

Implementation Method 1

The wire electrical discharge machine is thermally deformed when a change occurs in a temperature environment in which it is installed, in the temperature of a mechanical section, or in the temperature of the machining fluid. Such thermal deformation causes thermal displacement in which the position and tilt of the wire electrode are displaced

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2926936B1Wire electrical discharge machine having upper/lower guide thermal displacement correction function
Publication Date: 2019.02.20 FANUC LTD
  • EP2926936B1 patent drawingFigure 1A
  • EP2926936B1 patent drawingFigure 1B~3B
  • EP2926936B1 patent drawingFigure 2

AI summary

There is provided a wire electrical discharge machine that includes a temperature detection unit, an actual position correction amount calculation unit, a correction amount calculation unit, a correction amount adjustment unit, a position correction amount adjustment unit, and a corrective movement amount calculation unit. The actual position correction amount calculation unit calculates an actual position correction amount for an upper/lower guide section in accordance with reference position coordinates at a reference temperature and with actual position coordinates at a temperature different from the reference temperature. The correction amount calculation unit uses a prepared correction amount arithmetic expression. The correction amount adjustment unit calculates a correction amount adjustment value from the actual position correction amount and the position correction amount.