Wire Electric Discharge Machine Short-Circuit Start Control
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Solution Overview
Problem
Conventional wire electric discharge machines cannot start machining from small-diameter holes with burrs or oblique machining start holes due to short-circuit states, which often result in wire electrode fusion and require extensive setup to eliminate the short circuit.
Innovation Solution
A wire electric discharge machine with a discharge inducing circuit, current limiting resistance, voltage detection, and a control circuit that supplies a smaller current in a short-circuit state to prevent wire electrode fusion, and adjusts parameters like wire tension and fluid flow to facilitate discharge removal and transition to open state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a power supply voltage is applied and a discharge current is supplied to a machining gap when the wire electrode and workpiece are in a short-circuit state, then the wire electrode is fused due to Joule heat generated by the resistance of the wire electrode, but conventional machines avoid this state entirely which prevents machining from small-diameter holes with burrs or oblique machining start holes
Solution Approach 1:
The invention changes the electrical parameters (voltage and current) based on the machining state. When a short-circuit state is detected, the control circuit supplies a limited current that is sufficient to eliminate the short-circuit (remove burrs or create discharge gap) but controlled to prevent wire electrode fusion. Once the short-circuit is eliminated, normal discharge machining current is supplied.
Solution Approach 2:
The invention converts the harmful short-circuit state into a beneficial condition for machining initiation. Instead of avoiding the short-circuit state entirely, the system uses controlled current supply in the short-circuit state to actively eliminate the short-circuit condition (remove burrs or create initial discharge gap), thereby enabling successful machining start from difficult geometries.
2Reliability
If conventional machines avoid applying power supply voltage in short-circuit state to prevent wire electrode fusion, then wire electrode fusion is prevented, but machining cannot be started from small-diameter holes with burrs or oblique machining start holes
Solution Approach 1:
The system dynamically adjusts electrical parameters based on detected machining state. In short-circuit state, limited current is supplied to eliminate the short-circuit while controlling wire electrode temperature. After short-circuit elimination, normal discharge machining parameters are applied, enabling both wire protection and machining capability.
Solution Approach 2:
The control circuit continuously monitors the machining gap state (short-circuit detection) and adjusts the current supply accordingly. When short-circuit is detected, limited current is supplied; when short-circuit is eliminated, normal current resumes. This feedback mechanism enables safe machining initiation from difficult geometries while preventing wire electrode fusion.
3Reliability
If relative micro-distance movement is repeated to eliminate short-circuit state as in conventional technology, then short-circuit may be eliminated, but if the machining start hole is minute and close to wire diameter or extends obliquely with burrs, the possibility of eliminating short-circuit state is small
Solution Approach 1:
Instead of using mechanical movement to eliminate short-circuit, the invention uses controlled electrical current in the short-circuit state to actively remove the cause of short-circuit (burs or material bridging the gap). This converts the harmful short-circuit condition into a useful machining action that reliably eliminates the short-circuit state even in difficult geometries.
Solution Approach 2:
The invention replaces the mechanical approach (relative micro-distance movement) with an electrical approach (controlled current supply). The electrical current directly removes burrs or creates discharge gap through controlled erosion, which is more effective than mechanical movement for eliminating short-circuit in minute or oblique holes.
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 successful machining initiation from previously inaccessible small-diameter holes by controlling current and voltage to avoid wire electrode fusion and eliminate short circuits, enhancing productivity by reducing setup time and complexity.
Implementation Method 1
a voltage detection circuit that detects a voltage of the machining gap
Implementation Method 2
the wire electrode is fused due to Joule heat generated by the resistance of the wire electrode
Implementation Method 3
a discharge inducing circuit including a first DC power supply connected to a machining gap between a wire electrode and work via a first switching element and a current limiting resistance
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Even if a machining gap between a wire electrode and workpiece is in a short-circuit state at a start of machining by a wire electric discharge machine, a high-frequency voltage in a pulse shape is applied and a small current is supplied to an extent that the wire electrode is not fused only in an initial fixed time at the start of machining. Then, the short circuit is released, though instantaneously, and a discharge occurs in that instant and the short circuit state is eliminated by discharge repulsion thereof and therefore, machining can be started.