Plasma Detector Using Voltage Fluctuation Rate
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Solution Overview
Problem
Conventional plasma detectors for laser beam machines have complex structures due to the need for electric resistance measurement circuits, and detecting plasma harmful to machining is challenging using trace voltage fluctuations alone, as they are small and easily influenced by non-machining conditions.
Innovation Solution
A plasma detector for laser beam machines that utilizes voltage fluctuation detection, integration, and occurrence rate computation to identify plasma generation, eliminating the need for electric resistance measurement circuits and allowing for smooth machining by adjusting feeding speed and laser beam output based on detected plasma volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electric resistance measurement circuit is provided to detect plasma, then plasma detection capability is improved, but device complexity increases
Solution Approach 1:
The invention extracts the plasma detection function from the complex electric resistance measurement circuit and implements it using only the existing sensor electrode voltage detection capability. By analyzing voltage fluctuations of the sensor electrode that are already present in the trace control system, the patent achieves plasma detection without adding separate measurement circuits, thereby reducing device complexity while maintaining detection capability.
Solution Approach 2:
The sensor electrode voltage detection system serves dual purposes: it performs its original function for trace control (maintaining gap length) and simultaneously detects plasma generation through voltage fluctuation analysis. This multi-functionality eliminates the need for dedicated plasma detection circuits, resolving the contradiction between detection capability and device complexity.
2Device complexity
If trace voltage is used to detect plasma, then device complexity is reduced, but measurement precision deteriorates due to small and fluctuating voltage signals
Solution Approach 1:
The invention implements a feedback mechanism where voltage fluctuations detected from the sensor electrode are continuously monitored and analyzed. By integrating these fluctuation signals over time and comparing them against threshold values, the system accurately distinguishes plasma-generated fluctuations from normal trace control variations, thereby maintaining high measurement precision despite using the existing voltage detection system.
Solution Approach 2:
The system performs preliminary integration of voltage fluctuation signals before making plasma detection decisions. By accumulating fluctuation data over a predetermined time period and computing occurrence rates, the system prepares processed signals that enhance detection accuracy, allowing reliable plasma identification even from small and fluctuating voltage changes.
3Measurement precision
If torch feeding speed is frequently decreased to detect plasma, then plasma detection sensitivity is improved, but productivity decreases due to interrupted machining
Solution Approach 1:
The invention replaces the mechanical approach of decreasing torch feeding speed for plasma detection with an electrical signal analysis method. By substituting mechanical adjustment with electronic voltage fluctuation monitoring and occurrence rate computation, the system achieves sensitive plasma detection while maintaining constant machining speed, thereby preserving productivity and machining smoothness.
Data Source
AI summary
Voltage fluctuating time integrating means integrates voltage fluctuating time when voltage of a sensor electrode fluctuates as a voltage fluctuation integrated time, and voltage fluctuation occurrence rate computing means computes a rate of occurrence of voltage fluctuation for time on the basis of the voltage fluctuation integrated time integrated. By doing so, quantity of generated plasma can be taken as the rate of occurrence of voltage fluctuation, and plasma detection judging means can easily detect large volume of generated plasma on the basis of the computed voltage fluctuation occurrence rate. Then, it is not necessary to provide a circuit for measuring electric resistance between the sensor electrode and a workpiece as a conventional way, thereby avoiding complexly structured plasma detector.