Laser Nozzle Gap Control Using Actual Axis Posture Feedback
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Solution Overview
Problem
In laser machining, control delays cause deviations between the commanded and actual positions and postures of the machining nozzle, leading to difficulties in maintaining a constant gap between the nozzle and the workpiece, resulting in errors in the machined shape.
Innovation Solution
A laser machining device and method that includes a three-dimensional moving unit, a rotating unit, a gap amount detecting unit, a rotational position detecting unit, and a command calculating unit to generate a command signal for maintaining a constant gap, allowing the nozzle to be moved relative to the workpiece based on actual positions and postures, even with control delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the machining nozzle is moved three-dimensionally based on command position with control delay, then the machining process can proceed, but the actual position deviates from command position causing gap amount control error
Solution Approach 1:
The patent applies feedback control by detecting the actual gap amount between the machining nozzle and workpiece surface using a sensor, comparing it with the target gap amount, and generating correction amounts to adjust the machining nozzle position. This closed-loop feedback mechanism compensates for position deviations caused by control delays, maintaining accurate gap control throughout the machining process.
Solution Approach 2:
The patent calculates correction amounts in advance based on the detected gap amount and command position before executing the movement. By pre-calculating the necessary position adjustments and applying them proactively, the system compensates for upcoming control delays, ensuring the machining nozzle maintains the correct gap distance even during high-speed three-dimensional movement.
2Adaptability or versatility
If the machining nozzle is moved along the surface of the workpiece, then complex three-dimensional machining is enabled, but control delay causes deviation between command and actual position reducing machining accuracy
Solution Approach 1:
The system continuously detects the actual gap amount during three-dimensional movement and uses this feedback to calculate real-time correction amounts. This enables accurate gap control even when the machining nozzle follows complex three-dimensional paths, compensating for position deviations that occur during dynamic movement and rotation.
Solution Approach 2:
The patent implements dynamic gap control by continuously adjusting the machining nozzle position based on real-time gap detection and calculated corrections. The system adapts to changing positions and postures during three-dimensional movement, maintaining constant gap control throughout the machining process despite the complexity of the motion trajectory.
3Manufacturing precision
If correction amounts are calculated based on gap amount and command position, then gap control is attempted, but the corrected movement direction differs from actual axial direction causing control error
Solution Approach 1:
The patent transforms the one-dimensional gap control problem into a three-dimensional correction problem by calculating correction amounts in multiple directions (X, Y, Z axes). Instead of simply adjusting the gap distance, the system computes comprehensive position corrections that account for the machining nozzle's orientation and movement direction in three-dimensional space, resolving the mismatch between corrected movement direction and actual axial direction.
Data Source
AI summary
A unit vector calculating unit of a laser machining device obtains a unit vector based on respective current rotational positions of an A-axis and a B-axis. A movement command calculating unit, a speed command calculating unit, or a torque command calculating unit generates a command signal for maintaining a gap amount at a constant value, based on the unit vector, and the gap amount between a machining nozzle and a workpiece. With a servo control unit, on the basis of the command signal, an X-axis motor, a Y-axis motor, and a Z-axis motor are controlled, whereby the machining nozzle is moved relatively in three-dimensional directions with respect to the workpiece.