Wire EDM Voltage Filter Control for Stable Discharge Machining

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Solution Overview

Problem

Existing wire electrical discharge machines face instability in electrical discharge machining due to inappropriate noise removal by digital low-pass filters, leading to insufficient machining and potential electrode hunting.

Innovation Solution

A control device and method that includes an acquisition unit, a digital low-pass filter, a determination unit, and an adjustment unit to dynamically adjust the filter's parameters based on machining path and conditions, enhancing noise removal and response delay to stabilize machining.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a digital low-pass filter is used to remove noise from the machining voltage detection value, then the noise removal effect is improved, but the response delay increases

Engineering Contradiction:
Improvenoise removal effectVSAvoidresponse delay
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the low-pass filter parameter adjustable rather than fixed. The control device dynamically changes the filter parameter based on machining conditions (such as machining depth, wire tension, and detection value variations). This allows the system to adapt the noise removal strength in real-time, achieving effective noise filtering while maintaining appropriate response speed for different machining stages.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent directly implements parameter changes by modifying the low-pass filter parameter according to machining conditions. When machining depth increases or wire tension changes, the filter parameter is adjusted to maintain optimal noise removal performance. This parameter adaptation resolves the contradiction by allowing strong noise removal when needed while preserving response capability when machining conditions require faster reaction.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the low-pass filter parameter is set to remove noise effectively, then measurement precision is improved, but machining stability deteriorates due to electrode hunting

Engineering Contradiction:
Improvedetection value accuracyVSAvoidmachining stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements feedback by continuously monitoring machining conditions (machining depth, wire tension, detection value variations) and using this information to adjust the low-pass filter parameter. The control device calculates the variation amount of detection values and compares it against thresholds to determine appropriate filter settings. This feedback mechanism ensures that noise removal is optimized without causing excessive response delay that would lead to electrode hunting and machining instability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent applies dynamics by making the filter parameter adaptive rather than static. The system dynamically adjusts the low-pass filter parameter based on real-time machining conditions, including machining depth, wire tension, and detection value variation rates. This dynamic adaptation prevents the system from using overly aggressive filtering that would cause delay and instability, while still achieving effective noise removal when conditions permit.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If a fixed low-pass filter parameter is used, then device complexity is reduced, but adaptability to different machining conditions deteriorates

Engineering Contradiction:
Improvefilter parameter managementVSAvoidadaptability to machining conditions
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent implements self-service by enabling the control device to automatically adjust the low-pass filter parameter based on machining conditions without requiring manual intervention. The system monitors machining depth, wire tension, and detection value variations, then autonomously determines the appropriate filter parameter settings. This self-adjusting capability provides adaptability to different machining conditions while maintaining relatively simple device architecture, as the adjustment logic is integrated into the existing control system.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4599970A1Device and method for controlling wire electrical discharge machine
Publication Date: 2025.08.13 FANUC LTD
  • EP4599970A1 patent drawingFigure 1
  • EP4599970A1 patent drawingFigure 2
  • EP4599970A1 patent drawingFigure 3

AI summary

This device for controlling a wire electrical discharge machine according to one embodiment of the present disclosure is equipped with: an acquisition unit for acquiring a detection value of the machining voltage; a digital low-pass filter for outputting a correction value by removing noise from the detection value; a determination unit for making a first determination in which the degree of noise removal from the digital low-pass filter is determined, and/or a second determination in which the response lag of the digital low-pass filter is determined, on the basis of the shape of the machining path and the machining conditions; an adjustment unit for adjusting a parameter of the digital low-pass filter; and a machining control unit for controlling electrical discharge machining on the basis of the correction value.