Beam Scanner Calibration with Low-Power Powder-Grain Imaging
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Solution Overview
Problem
Existing methods for calibrating beam scanners in additive manufacturing devices that use energy beams to solidify powder materials are inefficient, material-wasting, and dependent on specific powder properties, leading to reduced productivity and process time.
Innovation Solution
A method involving imaging and comparing images of a detection region with and without a low-power energy beam scan to calibrate beam scanners without modifying the powder material, using radiation pressure to change grain positions and detect the scan path, allowing for precise calibration without chemical or physical transformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical and/or chemical transformations of powder material are used for calibration, then calibration can be carried out inside the working area, but productivity deteriorates and material is wasted
Solution Approach 1:
The patent uses a camera to capture images of the powder layer before and after beam scanning, creating a visual record (copy) of grain position changes. This image-based copying method replaces destructive physical/chemical transformations with non-invasive optical measurement, allowing calibration without material waste while maintaining accuracy.
Solution Approach 2:
The patent replaces physical/chemical transformation methods with radiation pressure-induced mechanical displacement of powder grains. The energy beam exerts radiation pressure to move grains to known positions, which are then detected by camera images. This substitution eliminates material transformation while enabling precise calibration.
2Measurement precision
If scattered emission detection is used for calibration, then calibration can be performed, but it strongly depends on powder material properties and requires dedicated optical sensors
Solution Approach 1:
The patent makes the powder material itself the calibration target by using its grains as the reference objects. The random distribution of powder grains serves as a natural marker system that is inherently present in the working area, eliminating the need for external calibration objects or dedicated sensors. The method adapts to any powder material since it uses the material's own grain structure for calibration.
3Measurement precision
If detectors or sensors are placed directly in the working area for energy beam detection, then calibration can be performed, but it is cumbersome and needs valuable process time
Solution Approach 1:
The patent introduces powder grains as intermediary objects that the energy beam acts upon. Instead of directly detecting the beam with sensors in the working area, the beam's effect (radiation pressure) is transferred to the powder grains, which then serve as detectable markers. This intermediary approach allows indirect measurement without requiring direct sensor placement, reducing process time.
Solution Approach 2:
The patent performs calibration using the existing powder layer that is already present in the working area before actual manufacturing begins. The calibration process uses the same powder material that will be used for manufacturing, eliminating the need for separate calibration objects and reducing setup time. The random grain distribution is prepared in advance as the calibration reference.
4Manufacturing precision
If high power density is used to modify powder material for calibration, then calibration patterns can be created, but the powder material is physically and chemically transformed
Solution Approach 1:
The patent changes the parameter of beam power density to a low level that causes only radiation pressure effects without physical or chemical transformation. By operating at low power density, the powder grains are displaced by radiation pressure but not melted, vaporized, or chemically altered. This parameter adjustment allows calibration while preserving the powder material's original properties.
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
Enables fast, high-productivity calibration that does not depend on powder material properties, avoiding material waste and reducing process time, while maintaining high manufacturing quality.
Implementation Method 1
a first power density of the at least one energy beam is chosen below a modification threshold of the powder material, such that the intrinsic physical and chemical properties of the powder material remain unchanged, such that at least one of a translational and an angular position of single grains of the powder material is changed
Data Source
Figure 1
Figure 2
Figure 3a~3d
AI summary
The invention relates to a method for calibrating at least one beam scanner (11) in a manufacturing device (1) for additively manufacturing an object (3) from a powder material (5), comprising steps: a) taking a first image (23) of a detection region (19) covered with a powder material (5) in the manufacturing device (1); b) controlling the at least one beam scanner (11) to scan at least one energy beam (9) along a predetermined scan path (25) in the detection region (19), wherein a first power density of the at least one energy beam (9) is chosen below a modification threshold of the powder material (5); c) taking a second image (27) of the detection region (19); d) comparing the first image (23) and the second image (27) and obtaining a comparative result (29), and e) calibrating the at least one beam scanner (11) on the basis of the comparative result (29).