Laser Machining Head Distance Control for Hole End Discoloration
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Solution Overview
Problem
Existing laser machining technologies face challenges in preventing discoloration near the machining end portion during inner hole cutting due to excessive laser irradiation, which is difficult to control with existing proximity sensors and control methods, leading to quality issues and processing speed limitations.
Innovation Solution
A laser machining apparatus equipped with a main control unit, a laser oscillator, a distance sensor, and a sensor-data processing unit that maintains a constant distance between the nozzle and the workpiece, allowing for precise control of laser light emission by stopping oscillation when the waste comes off, thereby preventing discoloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser light irradiation continues until the nozzle reaches the machining path end, then the cutting is completed, but excessive laser irradiation causes discoloration at the end portion
Solution Approach 1:
The system performs preliminary detection of waste separation using a distance sensor before the nozzle reaches the machining path end. When the waste is detected to have separated (distance exceeds threshold), the laser oscillation is stopped in advance, preventing excessive irradiation and discoloration at the end portion while ensuring cutting completion.
2Manufacturing precision
If the laser oscillation is stopped early to prevent discoloration, then the end portion quality is improved, but the cutting may be incomplete
Solution Approach 1:
The system uses a distance sensor to continuously monitor the distance between the workpiece and nozzle in real-time. When the waste separation is detected (distance > threshold), this feedback signal triggers immediate laser oscillation stoppage. This closed-loop feedback mechanism ensures the laser is stopped at the precise moment needed to prevent discoloration while completing the cut.
3Measurement precision
If a proximity sensor is used to detect the end point, then the machining end can be detected, but the response time is too slow to prevent discoloration
Solution Approach 1:
The system replaces the mechanical/proximity sensor-based detection method with a distance sensor that measures the actual distance between the workpiece and nozzle. This substitution enables faster response time (millisecond order) compared to proximity sensors, allowing the laser oscillation to be stopped quickly enough to prevent discoloration while maintaining accurate end point detection.
4Manufacturing precision
If the slot width is maintained constant through NC programming, then the machining precision is improved, but the system cannot adapt to slot width changes caused by cutting conditions and environment
Solution Approach 1:
The system uses the distance sensor to automatically detect waste separation and trigger laser stoppage without requiring manual NC program adjustments. This self-service mechanism adapts to varying slot widths caused by different cutting conditions and environmental factors, maintaining end portion quality while eliminating the need for complex NC programming to compensate for slot width variations.
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 solution improves cutting quality by reducing discoloration at the machining end and eliminates the need for secondary machining, enhancing processing efficiency and reducing secondary machining time and effort.
Implementation Method 1
a distance sensor that measures a distance between the nozzle and the workpiece
Implementation Method 2
a laser oscillator that oscillates the laser light in accordance with an instruction from the main control unit
Implementation Method 3
when a portion corresponding to the through hole in the workpiece comes off and a distance between the nozzle and the workpiece becomes larger than a predetermined value
Data Source
AI summary
A laser machining apparatus includes a main control unit executing NC program; a laser oscillator oscillating laser light according to instruction from the main control unit; a distance sensor measuring distance L between a nozzle and a workpiece; a sensor-data processing unit sampling a measured value of the distance sensor; and a copying control unit moving a machining head to maintain the distance constant based the measured value, wherein the sensor-data processing unit samples the measured value with an operation period shorter than that of the main control unit and, when a portion corresponding to the through hole in the workpiece comes off and the distance becomes larger than a predetermined value during the inner hole machining, causes oscillation of laser light to be stopped by outputting a stop signal to the laser oscillator.