Laser Scan Trajectory with Adaptive Path Overlap for Powder Bed Fusion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In selective additive manufacturing, the use of fixed scanning pitches in laser-based processes leads to thermal insulation areas, overheating, residual stresses, and porosity issues due to uneven heat distribution and thermal gradients, affecting the mechanical properties and quality of the manufactured parts.
Innovation Solution
A method to determine adaptive laser scanning trajectories by iteratively adjusting the positions of adjacent paths to achieve a target overlap rate within a predetermined tolerance interval, ensuring optimal fusion and minimizing overheating and unfused areas, using a process that estimates the transverse widths of fusion zones and adjusts the scanning step to maintain a consistent overlap rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed scanning pitch is used in laser-based selective additive manufacturing, then the manufacturing process is simple and fast, but thermal insulation areas and overheating occur due to uneven heat distribution
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed scanning pitch to an adaptive scanning pitch that varies along the trajectory. The scanning step is dynamically adjusted based on local geometric characteristics (curvature, distance from previous paths) to maintain optimal overlap between adjacent paths, thereby preventing both thermal insulation areas and overheating while preserving manufacturing efficiency.
Solution Approach 2:
The patent changes the parameter of scanning pitch from a constant value to a variable value that adapts to local conditions. By modifying the scanning step size based on curvature radius and distance to previous paths, the system optimizes heat distribution uniformity without significantly compromising manufacturing speed, thus resolving the contradiction between productivity and temperature uniformity.
2Ease of operation
If a fixed scanning pitch is used, then the process is easy to control, but thermal gradients cause residual stresses that deteriorate mechanical properties
Solution Approach 1:
The patent modifies the scanning pitch parameter from fixed to adaptive, calculating optimal step sizes based on local curvature and geometric features. This parameter change reduces thermal gradients and residual stresses, thereby improving mechanical properties while maintaining reasonable control complexity through automated calculation.
Solution Approach 2:
The patent implements a feedback mechanism where the scanning pitch is continuously adjusted based on real-time geometric analysis of the trajectory and previous path positions. This feedback loop optimizes heat distribution to prevent excessive thermal gradients, thereby protecting mechanical properties while keeping control manageable through systematic calculation.
3Productivity
If a fixed scanning pitch is used, then the manufacturing process is efficient, but overheating areas lead to porosity and Keyhole effect
Solution Approach 1:
The patent applies dynamics by making the scanning pitch adaptive rather than fixed. The system dynamically adjusts the scanning step based on local curvature and distance to previous paths, preventing overheating and Keyhole effect in critical areas while maintaining efficient manufacturing speed in less critical regions, thus resolving the contradiction between productivity and part quality.
Solution Approach 2:
The patent applies local quality by differentiating the scanning pitch according to local geometric characteristics. Areas with high curvature or close proximity to previous paths receive smaller scanning steps to prevent overheating and porosity, while other areas maintain larger steps for efficiency, thereby achieving both manufacturing efficiency and high part quality.
4Productivity
If the scanning step is increased to reduce production time, then productivity improves, but non-melted areas and pores appear between adjacent paths
Solution Approach 1:
The patent applies dynamics by adjusting the scanning pitch adaptively rather than using a uniformly increased step. The system calculates optimal local step sizes that ensure sufficient overlap for complete fusion while minimizing total trajectory length, thereby achieving both high production speed and complete fusion without pores or non-melted areas.
Solution Approach 2:
The patent changes the scanning step parameter from a uniformly increased value to a locally optimized variable value. By calculating appropriate step sizes based on curvature and geometric features, the system ensures complete fusion between adjacent paths while keeping the overall production time reduced, thus resolving the contradiction between productivity and fusion completeness.
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 approach results in more homogeneous thermal distribution, reduced production time, and improved mechanical properties by optimizing the overlap between adjacent paths, thereby enhancing the quality and consistency of the manufactured parts.
Implementation Method 1
a source to make the fusion of the layers of powder of high-power laser sources or electron beam sources
Implementation Method 2
emission of a laser beam on the powder layer according to a trajectory
Implementation Method 3
the laser locally brings enough energy to melt the layer of powder
Implementation Method 4
consolidation of selected areas on successive strata of pulvered material
Implementation Method 5
These gradients in turn lead to the appearance of residual constraints
Implementation Method 6
The increase in temperature in these local areas causes significant thermal gradients
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a method (P) for determining the path followed by a selective additive manufacturing laser beam of a three-dimensional object, the laser beam being intended to be emitted to a layer of powder and moved along a path consisting of a plurality of adjacent paths so as to melt the powder layer, characterised in that the paths are determined by implementing the following steps: a) determining, on a predetermined reference path (Ti), several reference points (Tij), b) determining several adjacent points (Ti+1j) located on the same side of the reference path, each adjacent point (Ti+1j) being associated with a reference point (Tij) and being such that a simulated adjacent melting zone which surrounds the adjacent point (Ti+1j) and a simulated reference melting zone which surrounds the reference point (Tij) have an overlap corresponding to a fraction of a transverse width of the simulated reference melting zone which is between a predetermined minimum fraction and a predetermined maximum fraction, c) determining an adjacent path (Ti+1) passing through the several determined adjacent points, d) iterating steps a) to c) using the determined adjacent path as a new reference path, so as to determine, in each iteration, a new adjacent path, the set of thus determined adjacent paths defining the path intended to be followed by the laser beam, the path being stored and/or transmitted to a control unit of a selective additive manufacturing device.