Wire EDM Fluid Level Control for Thermal Stability

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Solution Overview

Problem

Existing wire electric discharge machines face challenges in accurately measuring workpiece dimensions post-machining without detaching the workpiece, as temperature variations cause dimensional deviations due to contraction and expansion of the workpiece and machine table, leading to inaccurate measurements when the workpiece is measured in a drained fluid environment.

Innovation Solution

A wire electric discharge machine equipped with a work tank, a table, upper and lower guides, and a detachable measurement device with a sensor, featuring level detection and adjustment mechanisms to maintain the working fluid level during measurement, ensuring the workpiece remains immersed and minimizing temperature-induced dimensional deviations by controlling the fluid level in conjunction with the sensor's position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the work tank is completely drained of working fluid for measurement, then the touch probe can access the workpiece surface, but temperature variation causes workpiece and table contraction leading to measurement deviation

Engineering Contradiction:
Improvemeasurement accessibilityVSAvoiddimensional accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The working fluid is maintained continuously in the work tank during both machining and measurement operations. The level adjustment mechanism ensures the fluid level adapts to different operational states (machining vs measurement) while maintaining continuous presence, thereby eliminating temperature-induced contraction and expansion cycles that cause measurement deviations.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The working fluid level is made dynamically adjustable based on the operational mode. The level adjustment mechanism raises or lowers the fluid level according to whether the upper guide or measurement device should be submerged, allowing the system to adapt fluid presence to operational needs while maintaining thermal stability.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If the working fluid level is maintained high for measurement, then temperature stability is preserved, but the upper guide cannot be properly positioned

Engineering Contradiction:
Improvedimensional accuracyVSAvoidoperational flexibility
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The working fluid level adjustment mechanism dynamically changes the fluid level based on operational requirements. During measurement, the level is raised to submerge the workpiece while keeping the measurement device accessible. During machining, the level is adjusted to appropriate height for the upper guide position, providing operational flexibility while maintaining measurement accuracy when needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the physical parameter of working fluid level height to accommodate different operational modes. By adjusting this parameter, the system optimizes conditions for either machining or measurement without compromising the other function.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If the working fluid level is maintained low for machining, then the upper guide position is accessible, but the workpiece cannot be properly measured

Engineering Contradiction:
Improvemachining accessibilityVSAvoiddimensional accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The working fluid level is dynamically adjusted between low positions during machining (for upper guide accessibility) and high positions during measurement (for workpiece immersion and thermal stability). This dynamic adaptation resolves the contradiction between machining accessibility and measurement precision requirements.

Inventive Principle:
Principle #15Dynamics

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 configuration allows for more accurate dimension measurements by stabilizing the workpiece and machine table dimensions, reducing deviations caused by temperature variations, and ensuring consistent measurement conditions akin to the machining environment.

Implementation Method 1

temperature variation of the workpiece, and a set value of the temperature of the measuring environment... temperature variation... heat of a workpiece and the table of metal material contacting the working fluid is deprived as heat of evaporation, and thus the material contracts

Methodology Applied
Scientific EffectThermal equilibrium: Thermal Expansion

Implementation Method 2

level detection means for detecting a level of the working fluid in the work tank, and level adjustment means for adjusting the level of the working fluid

Methodology Applied
Scientific EffectFluid level control: Hydraulic Accumulator

Data Source

PatentEP3147062B1Wire electric discharge machine and method of operating a wire electric discharge machine
Publication Date: 2020.11.11 FANUC LTD
  • EP3147062B1 patent drawingFigure 1A
  • EP3147062B1 patent drawingFigure 1B
  • EP3147062B1 patent drawingFigure 2~3

AI summary

A wire electric discharge machine (1) of the present invention has a work tank containing a working fluid, a table provided in the work tank and on which a workpiece is mounted, an upper guide (14) and a lower guide (15) supporting a wire electrode (2), and a measurement device (3) detachable from or movable relative to an upper guide, the wire electric discharge machine being configured adjust the level of the working fluid when measuring such that the level not lower than a height of an upper surface of the workpiece.