Multiwire EDM Breakage Detection Using Parallel DC Monitoring
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Solution Overview
Problem
Conventional multiwire electric discharge machines face difficulties in detecting wire breakage accurately due to increased inductance with multiple turns of the wire electrode, making it challenging to apply a pulse voltage for breakage detection.
Innovation Solution
A multiwire electric discharge machine with a cutting wire section comprising multiple parallel cutting wires, equipped with a wire breakage detection unit that includes a wire breakage detection circuit with a direct current source and current limiting resistor, allowing for continuous monitoring of current flow to detect wire breakage accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of turns of the wire electrode increases, then the cutting capability is improved, but the inductance of the wire electrode increases making it difficult to apply pulse voltage for breakage detection
Solution Approach 1:
The patent changes the detection voltage type from pulse voltage to direct current (DC) voltage. This parameter change allows continuous monitoring of wire conduction state without being affected by the inductance problem that plagues pulse voltage application in multi-turn configurations. The DC voltage enables reliable breakage detection even when the wire electrode has many turns around guide rollers.
2Measurement precision
If a pulse voltage is applied to the wire electrode for breakage detection, then the conduction state can be checked, but the inductance prevents high-frequency current from flowing when the number of turns increases
Solution Approach 1:
The patent changes the voltage type from pulse voltage to direct current (DC) voltage. This parameter change eliminates the inductance-related problem of high-frequency current flow failure. The DC voltage continuously flows through the wire electrode regardless of the number of turns, enabling reliable conduction state measurement and breakage detection.
3Adaptability or versatility
If the wire electrode is wound around multiple guide rollers, then the multiwire cutting function is achieved, but the inductance increases making breakage detection difficult
Solution Approach 1:
The patent changes the detection method from pulse voltage to direct current (DC) voltage. This parameter change allows the system to maintain multiwire cutting capability through multiple guide rollers while simultaneously achieving reliable breakage detection. The DC voltage is not affected by the inductance generated by winding the wire around multiple rollers.
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 quick and accurate detection of wire breakage, independent of inductance issues, by applying a direct current and monitoring current fluctuations during machining.
Implementation Method 1
a wire breakage detection circuit that is an electric circuit in which a wire breakage detection power source and a current limiting resistor are connected in series, the wire breakage detection power source constantly supplying a direct current to the wire electrode portion
Implementation Method 2
cuts the workpiece by causing an electric discharge between the cutting wire section and the workpiece
Data Source
AI summary
A multiwire electric discharge machine includes: a machining power source that applies a machining pulse voltage between a workpiece and a cutting wire section; and a wire breakage detection unit that detects breakage of a wire electrode. The wire breakage detection unit is electrically connected in parallel to a wire electrode portion stretched over a section from one location on the feeding side of the wire electrode to one location on the ejection side of the wire electrode, and the wire breakage detection unit includes: a wire breakage detection circuit in which a wire breakage detection power source constantly supplying direct current to the wire electrode portion at least while the workpiece is undergoing a cutting process and a current limiting resistor are connected in series; and a wire breakage determination unit that determines breakage of the wire electrode based on current flowing through the current limiting resistor.