EDM Power Supply Circuit for Faster Current Regeneration
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Solution Overview
Problem
In electric discharge machines, the exponential decrease of current during the current fall time makes it difficult to shorten the workpiece machining time without increasing heat generation or compromising machining accuracy.
Innovation Solution
A power supply device with a current regeneration unit that includes a capacitive element and switching elements to maintain voltage at a higher level during current regeneration, causing current to decrease linearly and reducing heat generation, thereby shortening the current fall time and ensuring sufficient current pause time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a regeneration resistor is used to shorten current fall time, then the current fall time decreases, but heat generation increases in proportion to the resistance value
Solution Approach 1:
The invention changes the fundamental parameter of current decay from exponential to linear by replacing the resistance-based regeneration path with a capacitive voltage maintenance mechanism. The capacitor holds voltage at a higher level during current regeneration, forcing linear current decrease rather than exponential decay, thereby reducing heat generation while maintaining short current fall time
Solution Approach 2:
The invention substitutes the resistive current regeneration mechanism with a capacitive energy storage and release mechanism. Instead of using a regeneration resistor to dissipate energy, the system uses a capacitor to maintain voltage and control current decay, fundamentally replacing the thermal dissipation approach with an electrical field-based approach
2Productivity
If current pause time is shortened to reduce machining time, then productivity increases, but workpiece machining accuracy decreases
Solution Approach 1:
The invention enables continuous useful action by maintaining higher voltage during the current fall period through capacitor discharge. This allows the current to remain productive longer during the fall phase, effectively extending the useful machining action into the current fall period, thereby reducing the need for extended pause time while maintaining accuracy
3Use of energy by moving object
If current is regenerated through a resistance path, then current can be regenerated, but the current decreases exponentially making it difficult to reduce current fall time
Solution Approach 1:
The invention fundamentally changes the current decay parameter from exponential to linear by introducing a capacitive element that maintains constant voltage during regeneration. This parameter change transforms the natural exponential decay characteristic into a controllable linear decrease, enabling precise control of current fall time
Solution Approach 2:
The invention introduces dynamic control of voltage during current regeneration through the capacitor discharge mechanism. The capacitor dynamically maintains voltage at a higher level during the regeneration phase, actively controlling the current decay rate rather than passively allowing exponential decay, thereby enabling adjustable and optimized current fall time
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 allows for a significant reduction in workpiece machining time while maintaining accuracy and reducing heat generation, as the current falls linearly and energy efficiency is improved by eliminating the need for a regeneration resistor.
Implementation Method 1
a capacitive element which is arranged between a first connection point between the electrode and the first switching element and a second connection point between the workpiece and the second switching element
Implementation Method 2
a current supply unit for supplying a pulsed current to an electrode gap constituted by a workpiece and an electrode, which are opposed to each other with a predetermined gap, for electric-discharge machining a workpiece
Data Source
AI summary
A power supply device for an electric discharge machine includes a current supply unit for supplying a pulsed current to an electrode gap and a current regeneration unit for regenerating the current. The current supply unit includes a DC power supply, a first switching element, and a second switching element. The current regeneration unit includes a capacitor arranged between a first connection point between an electrode and the first switching element and a second connection point between a workpiece and the second switching element, and a third switching element which is arranged between a third connection point between the first connection point and the DC power supply and a fourth connection point between the second connection point and the capacitor and which is turned on from the start of current regeneration until the current value reaches zero, whereby regeneration current fall time is reduced.