EDM Gap Control Using Stepped Open Voltage and Ignition Delay
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Solution Overview
Problem
The slow response time of machine mechanics in EDM systems results in poor alignment of discharge sparks, affecting material removal rate, electrode wear, and surface quality due to the inability to follow the high discharge frequency of the EDM process.
Innovation Solution
A method that progressively increases the open voltage during machining pulses if a discharge does not occur within specified waiting times, calculating an average products sum to adjust servo setpoint values for gap width control, allowing for real-time adaptation of electrical parameters such as open voltage, pulse pause, and current amplitude to improve discharge alignment and process stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the quill response time is increased to follow the discharge frequency, then the alignment of discharge sparks improves, but the machine mechanics cannot respond fast enough due to its low eigenvalue
Solution Approach 1:
The patent replaces mechanical response with electronic control by using a compression adjustment processor that electronically modifies pulse compression based on detected ignition delay times. This electronic system responds at discharge frequency (50 kHz) rather than mechanical quill response time, enabling precise control of spark alignment without mechanical inertia limitations.
Solution Approach 2:
The system continuously detects ignition delay time and uses this feedback to dynamically adjust pulse compression through the processor. This closed-loop feedback mechanism allows real-time correction of gap width variations, ensuring discharge sparks remain properly aligned despite mechanical response limitations.
2Productivity
If the open voltage is increased to reduce ignition delay, then the discharge frequency increases, but the gap width increases reducing machining accuracy
Solution Approach 1:
The system dynamically adjusts pulse compression rather than using fixed high open voltage. The compression adjustment processor continuously modifies the compression level based on real-time ignition delay detection, allowing the system to optimize between productivity and precision dynamically rather than being locked into a static high-voltage mode.
Solution Approach 2:
Instead of changing only open voltage, the system changes the pulse compression parameter based on detected ignition delay. This alternative parameter adjustment achieves ignition delay reduction without the harmful side effect of increased gap width, thereby maintaining machining accuracy while improving productivity.
3Stability of the object's composition
If the filter frequency is adjusted to reduce machine head instability, then the process stability improves, but the response time increases
Solution Approach 1:
The patent replaces mechanical filtering with electronic signal processing. The compression adjustment processor electronically analyzes ignition delay times and adjusts compression accordingly, achieving stability control at discharge frequency without the time delays inherent in mechanical filtering systems.
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 enhances the performance and stability of the EDM process by minimizing unproductive time and maintaining reproduction accuracy, improving material removal rate and surface quality without increasing surface roughness or heat-affected zone.
Implementation Method 1
an open voltage is applied between the electrode and the workpiece to induce a discharge
Data Source
Figure 1~2
Figure 3~5
Figure 4~6b
AI summary
The invention relates to a method and device for electrical discharge machining (EDM) a workpiece by means of a train of machining pulses. During the machining time the machining pulses are applied to the working gap between workpiece and electrode. An open voltage is first applied, and it is increased to a second open voltage level if a discharge does not occur within a waiting time do, and further increased to a third open voltage level if a discharge does not occur within a second waiting time d1. An average product of the actual open voltages times the partial ignition delays is computed and subtracted from the product of a reference open voltage times the total ignition delay, and the servo setpoint value is adjusted accordingly. The actual axes positions are sampled in real time and the discharge electrical parameters are adjusted accordingly. The discharge electrical parameters can be adjusted according to the duration of d0 and d1. Moreover, a micro oscillation can be imposed to the axes.