On-Axis Melt Pool Sensor Alignment for Stable Scan-Direction Signals
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Solution Overview
Problem
Existing on-axis melt pool sensors in additive manufacturing apparatuses experience signal intensity variations due to misalignments when the laser beam scan direction changes, obscuring anomalies like splatter particles or porosity, especially in laser-based powder bed fusion systems.
Innovation Solution
A method to align the on-axis melt pool sensor by scanning a first laser beam and a field of view across the working surface using intersecting scan paths, adjusting the alignment based on signal variations to compensate for misalignments, using either manual or motorized mechanisms to correct the sensor's field of view relative to the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the laser beam scan direction is changed, then the coverage area is improved, but the signal intensity stability deteriorates
Solution Approach 1:
The sensor alignment is pre-adjusted so that the field of view is centered on the optical axis of the second optical train. This preliminary alignment ensures that regardless of which scan direction is used, the sensor consistently captures the melt pool at the center of its field of view, eliminating signal intensity variations caused by directional misalignment.
Solution Approach 2:
The alignment parameters of the sensor are adjusted based on the determined misalignment. By changing the sensor's angular or positional parameters to compensate for the misalignment, the field of view is realigned with the optical axis, ensuring consistent signal intensity across all scan directions.
2Device complexity
If the field of view is not aligned with the optical axis, then the device complexity is reduced, but the measurement precision deteriorates
Solution Approach 1:
The system uses the signal intensity variations from different scan directions as feedback to determine the misalignment of the sensor. By analyzing the pattern of signal intensity changes, the system calculates the required alignment adjustment and applies it to center the field of view on the optical axis, thereby improving measurement precision.
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 alignment method stabilizes signal intensity, preventing dips and ensuring accurate detection of melt pool anomalies, enhancing the reliability of additive manufacturing processes.
Implementation Method 1
the radiation may be radiation emitted by the melt pool itself (typically infra-red wavelengths)
Implementation Method 2
Portions of the powder layer corresponding to a cross-section of the workpiece to be formed are then solidified through irradiating these areas with the beam. The beam melts or sinters the powder to form a solidified layer.
Data Source
AI summary
A method of aligning an on-axis melt pool sensor in an additive manufacturing apparatus. The method includes scanning a first laser beam along a first scan path across a working surface using a first optical train to generate a melt pool along the first scan path and scanning a field of view of an on-axis sensor along a second scan path across the working surface using a second optical train for steering a second laser beam. The first and second scan paths intersect. An adjustment to be made to an alignment of the field of view of the on-axis sensor with an optical axis of the second optical train is determined from a variation in the signal generated by the on-axis sensor as the field of view is scanned along the second scan path.