Wire EDM Power Supply Segmentation for Copper Deposition
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Solution Overview
Problem
Existing power supply systems for wire electric discharge machining suffer from the adverse effects of floating capacitors in low inductance lines, leading to decreased material removal rates due to blunt voltage rising edges and increased copper deposition on the workpiece, which can cause wire electrode breakage and reduced machining efficiency.
Innovation Solution
A power supply system incorporating a first DC power supply with a current limiting resistor, a second DC power supply with a low inductance line, and a blocking diode series-connected between the low inductance line and the machining gap, along with a snubber circuit and cooling unit to minimize the effect of floating capacitors and maintain a steep current pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large current is supplied to the machining gap at high frequency, then the material removal rate is improved, but the wire electrode has a risk of breaking
Solution Approach 1:
The power supply system is divided into two independent circuits: a first power supply circuit that supplies high voltage with limited current, and a second power supply circuit that supplies large current with steep edges. This segmentation allows each circuit to perform its specialized function without compromising the other, enabling high material removal rate while protecting the wire electrode from breaking
Solution Approach 2:
The first power supply circuit acts as an intermediary that generates the electric discharge to initiate the machining process, while the second power supply circuit provides the main current for material removal. The coordinated operation of these two circuits enables both high productivity and wire electrode protection
2Reliability
If a current limiting resistor with large resistance value is used, then the current supplied to the machining gap is limited, but the voltage rising edge becomes slow
Solution Approach 1:
The voltage supply and current supply functions are segmented into two separate circuits. The first circuit uses a current limiting resistor to provide controlled voltage and initiate discharge, while the second circuit provides the main current with steep edges through low inductance connection, eliminating the trade-off between current limitation and voltage rising edge speed
Solution Approach 2:
The first power supply circuit with current limiting resistor serves as an intermediary that prepares the machining gap for discharge by providing controlled voltage, while the second power supply circuit delivers the main current pulse. This intermediary role allows the current limiting resistor to function without compromising the overall system performance
3Productivity
If a low inductance line is used to supply large current, then the current pulse has steep edges, but floating capacitors cause copper deposition on the workpiece
Solution Approach 1:
The first power supply circuit acts as an intermediary that controls the current flow characteristics by limiting the current from floating capacitors while allowing the main current from the second circuit to pass through. This intermediary function prevents copper deposition while maintaining the benefits of the low inductance line for high productivity
Solution Approach 2:
The system changes the current flow parameters by using two different power supply circuits with different characteristics. The first circuit limits current to prevent copper deposition, while the second circuit provides large current for high material removal rate. The coordinated parameter control of both circuits resolves the contradiction
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
The solution effectively reduces copper adherence on the workpiece, maintains a steep current pulse, and enhances machining speed by minimizing the impact of floating capacitors, thereby improving material removal rates and preventing wire electrode breakage.
Implementation Method 1
A blocking diode is disposed between the inductance line and the machining gap. The blocking diode prevents a current from flowing from a floating capacitor in the inductance line to the machining gap.
Implementation Method 2
a container that has a contact surface contacting with the blocking diode and contains cooling liquid
Implementation Method 3
a wire electric discharge machining apparatus for machining a work piece by causing electric discharge to a machining gap formed between a wire electrode and the work piece
Implementation Method 4
the current pulse is desirable to have a high current peak, a steep rising edge and a steep falling edge
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A power supply system for wire electric discharge machining includes a first power supply circuit (10) and a second power supply circuit (20). The first power supply circuit applies, to the machining gap, a voltage that induces a discharge. The second power supply circuit, which includes a low inductance line (30), supplies a current (12), which contributes to the machining, to the machining gap,. A blocking diode (41) is series-connected between the low inductance line and the machining gap. A container (50), which has a contact surface (56) contacting with the blocking diode and contains a cooling liquid, is provided.