Selective Powder Melting Calibration Using Optical Reference Points
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Solution Overview
Problem
Existing calibration methods for selective powder melting systems suffer from dynamic interference due to mechanical uncertainties and additional degrees of freedom in the positioning of the scan plate, leading to positional deviations and slow convergence or restarts in the calibration process.
Innovation Solution
Eliminate mechanical uncertainties by using optical reference points on the scan field plate independent of mechanical coupling, and adjust calibration data based on relative positions to achieve precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a scan plate is mechanically positioned within the machine for calibration, then calibration can be performed, but mechanical uncertainties and additional degrees of freedom cause dynamic interference and positional deviations
Solution Approach 1:
The patent replaces the mechanical positioning system with an optical system. Instead of relying on mechanical degrees of freedom for scan plate positioning, the invention uses optical reference points and a camera-based measurement system to determine positions. This substitution eliminates mechanical uncertainties and dynamic interference, achieving more reliable and precise calibration measurements.
2Manufacturing precision
If multiple iterations are performed to approximate actual coordinates to target values, then calibration accuracy improves, but processing time increases and convergence may fail due to dynamic disturbances
Solution Approach 1:
The patent performs preliminary actions by establishing optical reference points and capturing images before the iterative calibration process begins. The measurement grid is inscribed and the camera captures the entire field of view with all reference points in a single shot, preparing all necessary measurement data in advance. This preliminary setup enables faster convergence during iteration and reduces the total calibration time.
Solution Approach 2:
The patent implements feedback by using the camera-captured images of optical reference points to determine actual positions, compare them with target positions from calibration data, and generate corrections. This feedback loop allows the system to quickly converge to accurate coordinates with fewer iterations, reducing calibration time while maintaining high precision.
3Measurement precision
If the laser beam inscribes a measurement grid onto the scan plate, then actual coordinates can be measured, but mechanical positioning uncertainties affect the measurement accuracy
Solution Approach 1:
The patent introduces optical reference points as intermediaries between the laser beam and the scan plate. Instead of directly measuring the laser's mechanical position, the system uses optical reference points that are illuminated by the laser and captured by a camera. This intermediary approach transfers the measurement from the mechanical domain to the optical domain, eliminating mechanical positioning uncertainties while simplifying the overall system.
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
Improves precision and convergence by eliminating mechanical errors, allowing for automated and efficient calibration with reduced rotational and spatial deviations.
Implementation Method 1
a controllable optical unit which in turn comprises a laser source, a plurality of lenses and a mirror arrangement with a plurality of adjustable mirrors, which is configured to selectively direct a laser beam emitted by the laser source to a point in the build chamber at which the material powder is to be melted
Implementation Method 2
each powder layer is heated with a focused laser beam
Implementation Method 3
a plurality of lenses and a mirror arrangement with a plurality of adjustable mirrors, which is configured to selectively direct a laser beam
Implementation Method 4
a plurality of lenses and a mirror arrangement
Data Source
Figure 1~2
AI summary
The present invention relates, inter alia, to a method for calibrating a system (10) for producing objects made of a material powder according to the method of selective powder melting, the system (10) comprising: a build chamber (22) which is provided to receive the powder to be melted and the object to be produced; a building plate support (24) which is provided in a vertically adjustable manner in the build chamber (22) and is provided to support thereon a building plate with the object to be produced; and a controllable optical unit (20) comprising a laser source (18), a plurality of lenses (16) and a mirror arrangement having a plurality of mirrors (14) arranged in an adjustable manner, which optical unit is configured to selectively direct a laser beam (L) emitted from the laser source (18) to a point (S) in the build chamber at which the material powder is to be melted. The method comprises the following steps: placing a scanning field plate (26) on the building plate support (24) in the build chamber (22); creating a plurality of optical reference points on the scanning field plate (26) at predefined positions with the aid of the controllable optical unit (20); creating a measuring grid (M) on the scanning field plate (26) with the aid of the controllable optical unit (20) by correspondingly adjusting the mirrors (14) of the mirror arrangement on the basis of a calibration data set; and determining the relative positionings between the optical reference points and the measuring grid.