Wire EDM Shape Correction Using Predicted Inter-Electrode Distance
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Solution Overview
Problem
Existing control systems for wire spark erosion machines struggle to accurately perform shape correction machining, especially when there are sudden changes in shape due to previous machinings, as they rely on averaging voltage or discharge frequency, leading to delays and incomplete shape correction.
Innovation Solution
A control device for a wire spark erosion machine that includes a storage device for data from previous machinings and a computation device to calculate inter-electrode distances and adjust machining parameters such as speed, discharge frequency, and drive trajectory to achieve precise shape correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If feedback control is performed by directly monitoring the voltage or electrical discharge frequency, then the control response speed is improved, but the control system becomes unstable due to high-frequency fluctuations
Solution Approach 1:
The patent applies different processing methods to different frequency components of the control signal. High-frequency fluctuations are filtered out through averaging, while low-frequency meaningful changes are preserved and used for control. This local differentiation in signal processing resolves the contradiction by stabilizing the control system without sacrificing essential response capability.
Solution Approach 2:
The patent introduces an intermediary averaging mechanism between the raw voltage/discharge frequency measurements and the control actuation. This intermediary process smooths out high-frequency fluctuations while preserving the underlying control signal, thereby stabilizing the control system without completely eliminating response capability.
2Stability of the object's composition
If averaging of voltage or discharge frequency is used for feedback control, then the control system stability is improved, but the shape correction accuracy deteriorates due to control delay
Solution Approach 1:
The patent performs preliminary averaging of the voltage or discharge frequency data before using it for feedback control. By pre-processing the signal to remove high-frequency fluctuations, the system achieves stable control while the averaged signal still contains the necessary low-frequency information for accurate shape correction, thus resolving the contradiction between stability and precision.
3Manufacturing precision
If the inter-electrode distance varies depending on the machining location, then the shape correction capability is improved, but the surface roughness and machining dimension variations increase
Solution Approach 1:
The patent implements feedback control by monitoring the voltage or discharge frequency and adjusting the machining parameters accordingly. The feedback mechanism detects variations in inter-electrode distance and compensates for them by modifying the electrode feed rate or discharge parameters, thereby maintaining consistent surface roughness while achieving accurate shape correction.
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 control device enables more accurate shape correction machining by predicting inter-electrode distances and adjusting machining parameters in real-time, effectively addressing sudden shape changes and improving surface roughness and shape accuracy.
Implementation Method 1
By applying a high voltage between the electrodes or shortening the distance between the electrodes to increase the electric field strength, electrical discharge is generated due to dielectric breakdown
Implementation Method 2
In the case of estimating the inter-electrode distance with the voltage or the electrical discharge frequency, the voltage or the electrical discharge frequency fluctuates at a high frequency
Data Source
AI summary
Provided is a control device for a wire spark erosion machine, the control device controlling a drive trajectory of an electrode, a machining speed, and an electrical discharge frequency, the control device including a storage device and a computation device. The storage device stores at least one of data selected from an inter-electrode average voltage, the electrical discharge frequency, the machining speed, and the drive trajectory in an (n−1)-th machining, where n is an integer of two or more. The computation device calculates an inter-electrode distance in an n-th machining using a calculation model indicating a relationship between the data in the (n−1)-th machining and a machining shape of the workpiece, and computes, from the inter-electrode distance, at least one command value selected from the machining speed, the electrical discharge frequency, and the drive trajectory in the n-th machining.