Wire Electrical Discharge Machine Tension Detection

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Solution Overview

Problem

Conventional wire electrical discharge machines fail to detect the position of a wire electrode on the wire feed path and its feed state accurately, especially when the wire electrode strays away from the original path or is not stuck on an object, leading to incomplete machining.

Innovation Solution

A wire electrical discharge machine equipped with a supply roller, collection roller, guide parts, fluid paths for compressed fluid supply, a tension detector, and a control device that determines the wire electrode's position by monitoring tension changes and controlling the fluid supply, allowing accurate detection of the wire electrode's position and feed state through sequential fluid path activation and pressure variation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If only flexure detection is used to detect wire electrode getting stuck, then the detection method is simple, but it is impossible to detect how far the wire electrode has proceeded on the wire feed path

Engineering Contradiction:
Improvewire electrode position detectionVSAvoiddetection system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The wire feed path is divided into multiple sections with fluid paths supplied at different positions. By detecting tension changes in each section sequentially, the system can determine the wire electrode's position along the feed path without requiring a single complex detection system.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A tension detector is introduced as an intermediary device to indirectly measure the wire electrode's position. Instead of directly tracking the wire's location, the system uses tension changes caused by compressed fluid supply to infer position, simplifying the overall detection mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If compressed fluid is supplied to feed the wire electrode along the wire feed path, then the wire electrode can be conveyed accurately, but it is difficult to determine whether the wire electrode has reached the supply position

Engineering Contradiction:
Improvewire electrode position detectionVSAvoidposition detection difficulty
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The tension detector provides real-time feedback on wire electrode tension as compressed fluid is supplied. When the wire reaches the fluid supply position, a characteristic tension change occurs, allowing the control device to automatically determine arrival at the supply position through this feedback signal.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system monitors changes in wire electrode tension as a parameter to detect position. By observing how tension varies when compressed fluid is supplied versus when it is not, the system can determine whether the wire has reached the supply position without direct visual or physical contact detection.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If multiple fluid paths are supplied at different positions along the wire feed path, then the position detection accuracy is improved, but the device complexity increases

Engineering Contradiction:
Improvewire electrode position detectionVSAvoidfluid path system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The compressed fluid supply system serves multiple functions: it both feeds the wire electrode along the feed path and enables position detection. The same fluid paths that convey the wire also create the tension changes used for detection, eliminating the need for separate detection infrastructure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The wire electrode itself serves as the detection medium. As the wire is fed through the compressed fluid supply positions, its own tension changes provide the detection signal. The system uses the wire's physical response to the fluid supply rather than requiring external sensors at each position.

Inventive Principle:
Principle #25Self-service

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 precise detection of the wire electrode's position and feed state, preventing errors due to noise in tension detection and ensuring efficient machining by determining the correct position of the wire electrode on the feed path.

Implementation Method 1

a tension detector configured to detect the tension of the wire electrode

Methodology Applied
Scientific EffectTension detection: Tension

Implementation Method 2

a fluid path formed with the guide part to supply a compressed fluid to the wire feed path so as to feed the wire electrode along the wire feed path

Methodology Applied
Scientific EffectCompressed fluid propulsion: Pressure Gradient

Data Source

PatentEP3318359B1Wire electrical discharge machine and auto wire feeding method
Publication Date: 2019.10.02 FANUC LTD
  • EP3318359B1 patent drawingFigure 1
  • EP3318359B1 patent drawingFigure 2
  • EP3318359B1 patent drawingFigure 3

AI summary

A wire electrical discharge machine (10) having an auto wire feeding function includes: guide parts arranged on a wire feed path along which the wire electrode (12) is fed so as to guide the feeding of the wire electrode (12); fluid paths (FP) formed with the guide parts to supply a compressed fluid to the wire feed path; a compressed fluid supply device (16) to supply the compressed fluid to the fluid paths (FP); a tension detector (34) to detect the tension of the wire electrode (12); and a control device (18) that controls the compressed fluid supply device (16) so as to supply the compressed fluid to the fluid paths (FP), and based on the detection result from the tension detector (34), determines whether or not the wire electrode (12) has reached a supply position (SP) of one of the fluid paths (FP) on the wire feed path to which the fluid has been supplied.