Wire EDM Peak Current Compensation for Precision Machining

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Solution Overview

Problem

Existing wire electric discharge machines face challenges in achieving high precision machining due to variations in current flow affecting machining speed and precision, with existing techniques experiencing time delays and inability to compensate actual machining current, leading to suboptimal results.

Innovation Solution

A wire electric discharge machine that computes and compensates the power source voltage in real-time using detected average electric current and discharge frequency, distinguishing between approach and main machining phases to accurately adjust voltage before starting the machining process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If output voltage is adjusted by detecting peak current and output voltage and comparing with reference values, then machining precision can be improved, but time delay is generated from detection to adjustment

Engineering Contradiction:
Improvemachining precisionVSAvoidtime delay
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by measuring and compensating the average open voltage before machining begins. The control unit measures the average open voltage between electrode and workpiece in the open state, compares it with reference voltage, and adjusts the output voltage beforehand. This eliminates time delay during actual machining while maintaining precision control.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of detecting and adjusting during machining (which causes time delay), the patent inverts the approach by measuring and compensating voltage in the open state before machining starts. This reverse timing approach eliminates the time delay problem while achieving the same precision control objective.

Inventive Principle:
Principle #13The other way round (Inversion)

2Device complexity

If only average open voltage is measured and compensated before machining, then control simplicity is maintained, but actual machining current cannot be compensated

Engineering Contradiction:
Improvecontrol simplicityVSAvoidmachining precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent implements feedback by measuring the average open voltage, comparing it with reference voltage, and using the comparison result to adjust the output voltage. This closed-loop feedback mechanism ensures that the actual machining current is properly compensated while maintaining control simplicity through automated voltage adjustment.

Inventive Principle:
Principle #23Feedback

3Stability of the object's composition

If machining current is not compensated for variations in electric discharge route impedance, then system stability is maintained, but machining speed and precision are affected

Engineering Contradiction:
Improvesystem stabilityVSAvoidmachining precision
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by measuring and compensating the output voltage before machining begins. By adjusting the voltage in advance based on the measured average open voltage, the system pre-compensates for impedance variations in the electric discharge route, ensuring stable and precise machining without requiring complex real-time adjustments.

Inventive Principle:
Principle #10Preliminary action

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 approach enables precise control and compensation of the machining power source voltage, reducing time delays and improving machining precision by considering the workpiece's influence and state, ensuring accurate shaping of desired products.

Implementation Method 1

applies electric voltage between a wire electrode and a workpiece to generate electric discharge between them

Methodology Applied
Scientific EffectElectric discharge: Electric Spark

Data Source

PatentEP2730361B1Wire electric discharge machine having peak current compensation function
Publication Date: 2021.11.24 FANUC LTD
  • EP2730361B1 patent drawingFigure 1~2
  • EP2730361B1 patent drawingFigure 3~4
  • EP2730361B1 patent drawingFigure 5

AI summary

A wire electric discharge machine is configured to machine a workpiece by computing an electric current at the machining time before starting a main machining and compensating a power source voltage for machining. The wire electric discharge machine measures an average electric current and an electric discharge frequency at the machining time, in a measuring section in an approach (42) before the main machining, and computes a peak current at the machining time. Further, an electric voltage of a machining power source is compensated by comparing the computed peak current at the machining, with a reference peak current.