Wire Electric Discharge Machine Tensile Force Calibration

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Solution Overview

Problem

Existing wire electric discharge machines face challenges in precisely controlling the tensile force of wire electrodes, leading to machining precision issues and the risk of wire electrode cutting due to inadequate detection and feedback control capabilities.

Innovation Solution

A wire electric discharge machine with a tensile force generating unit, detector, and calibrating unit that corrects detected deviations in tensile force measurements to achieve precise feedback control, enhancing machining precision and preventing wire electrode cutting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a tensile force detector is used to measure and feedback control the tensile force of a wire electrode, then the tensile force can be controlled within a certain range, but the detection precision is insufficient for minute or fine differences in tensile force

Engineering Contradiction:
Improvetensile force detection precisionVSAvoidmachining precision
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent changes the detection parameter from direct tensile force measurement to measurement of physical quantities (displacement, voltage, current) that correlate with tensile force. By detecting these alternative parameters and establishing their relationship with tensile force, the system achieves higher detection precision for minute force differences while maintaining machining precision through feedback control.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the tensile force applied to the wire electrode is increased to suppress vibration and improve machining precision, then the machining precision is improved, but the wire electrode may be cut and machining interrupted

Engineering Contradiction:
Improvemachining precisionVSAvoidwire electrode integrity
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent implements feedback control by continuously detecting tensile force (or correlated physical quantities) and adjusting the applied force based on detected deviations. This allows the system to maintain optimal tensile force for vibration suppression while preventing excessive force that would cut the wire electrode, thereby simultaneously achieving high machining precision and wire electrode integrity.

Inventive Principle:
Principle #23Feedback

3Reliability

If the tensile force applied to the wire electrode is decreased to prevent wire cutting, then the wire electrode integrity is maintained, but vibration cannot be suppressed and machining precision deteriorates

Engineering Contradiction:
Improvewire electrode integrityVSAvoidmachining precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent employs dynamic adjustment of tensile force through feedback control, allowing the system to optimize the balance between wire electrode integrity and vibration suppression. By continuously monitoring detection signals and adjusting applied force in real-time, the system adapts to varying conditions to maintain both reliability and machining precision.

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

The solution allows for precise detection and control of tensile force, improving machining precision and preventing wire electrode cutting by accounting for deviations in tensile force measurements, thereby enhancing the overall performance of wire electric discharge machining.

Implementation Method 1

a tensile force detector for detecting a tensile force of the wire electrode

Methodology Applied
Scientific EffectTensile force detection:

Implementation Method 2

a wire electrode is wound around a brake roller connected to an electromagnetic brake

Methodology Applied
Scientific EffectElectromagnetic brake: Electromagnet

Implementation Method 3

In a wire electric discharge machine, an appropriate tensile force is applied to a wire electrode and electric discharge is carried out

Methodology Applied
Scientific EffectElectric discharge: Electric Arc

Data Source

PatentEP3064302B1Wire electric discharge machine having function to correct detected value of tensile force
Publication Date: 2020.04.22 FANUC LTD
  • EP3064302B1 patent drawingFigure 1
  • EP3064302B1 patent drawingFigure 2~3
  • EP3064302B1 patent drawingFigure 4~5

AI summary

There is provided a wire electric discharge machine including a calibrating unit which carries out calibration for obtaining a detected deviation amount of the tensile force detector based on the set tensile force and a tensile force detected by the tensile force detector when the set tensile force is applied, the calibrating unit correcting output of the tensile force detector by the detected deviation amount which is obtained by the calibration, and the wire electric discharge machine carries out feedback control of the tensile force of the wire electrode based on a corrected detected tensile force which is obtained by correcting the detected tensile force of the tensile force detector by the calibrating unit.