Adaptive Laser Scan Paths for Uniform Melt Zone Overlap
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Solution Overview
Problem
Selective additive manufacturing processes using high-power laser sources face issues with thermal gradients and residual stresses due to non-uniform heat distribution and overheating, leading to mechanical property degradation and production inefficiencies, particularly in the formation of pores and material splashing.
Innovation Solution
A method to determine an optimized laser-scan trajectory by iteratively adjusting the positions of adjacent paths to achieve a targeted overlap between melt zones, ensuring a uniform thermal distribution and preventing overheating, thereby improving the quality and efficiency of the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a constant scan pitch is used in laser-scan trajectory, then the manufacturing process is simple and fast, but thermal gradients and residual stresses appear causing mechanical property degradation
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant scan pitch to a dynamic adaptive scan pitch that varies along the trajectory. The scan pitch is adjusted based on real-time thermal state assessment, allowing the process to adapt to changing thermal conditions and maintain uniform thermal distribution while preserving manufacturing efficiency.
Solution Approach 2:
The patent implements parameter changes by modifying the scan pitch parameter dynamically during the manufacturing process. Instead of using a fixed scan pitch value, the system changes the scan pitch according to the assessed thermal state, thereby optimizing thermal distribution uniformity without significantly compromising productivity.
2Speed
If high-power laser source is used to melt powder layers, then consolidation speed is high, but overheating and keyhole regime appear creating pores
Solution Approach 1:
The patent applies feedback by implementing a thermal state assessment mechanism that continuously monitors the thermal conditions during laser melting. This feedback information is used to dynamically adjust the scan pitch, allowing the system to maintain high consolidation speed while preventing overheating and keyhole regime formation that lead to pores.
Solution Approach 2:
The patent uses dynamics by making the scan pitch adaptive rather than fixed. The dynamic adjustment of scan pitch based on thermal state assessment enables the system to respond to changing thermal conditions during melting, preventing pore formation while maintaining high consolidation speed.
3Productivity
If adjacent paths are separated by large pitch, then productivity increases, but unmelted zones appear between paths causing surface quality degradation
Solution Approach 1:
The patent implements parameter changes by dynamically adjusting the scan pitch parameter along the trajectory. The scan pitch is increased in regions where thermal accumulation is sufficient to ensure complete melting, thereby improving productivity while maintaining surface quality through adaptive parameter modification.
Solution Approach 2:
The patent applies local quality by allowing the scan pitch to vary locally along different segments of the trajectory. In regions where thermal conditions ensure complete melting, larger pitch values are used to improve productivity, while in other regions smaller pitch values maintain surface quality, thereby optimizing both productivity and surface quality locally.
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
The method ensures a more uniform thermal distribution, reduces production time, and minimizes the formation of pores and mechanical property degradations, resulting in improved mechanical properties and surface quality of the manufactured parts.
Implementation Method 1
a laser source, and configured to emit the laser beam onto the layer of powder following a trajectory made up of a plurality of adjacent paths, the passage of the laser beam over these paths causing the layer of powder to melt
Data Source
AI summary
A method (P) for determining trajectory followed by a laser beam for selective additive manufacture of a three-dimensional object comprises: a) determining, on a predetermined reference path (Ti), a plurality of reference points (Tij), b) determining a plurality of 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 melt zone that surrounds said adjacent point (Ti+1j) and a simulated reference melt zone that surrounds the reference point (Tij) have an overlap corresponding to a fraction of a transverse width of the simulated reference melt zone that is comprised between a predetermined minimum fraction (αmin) and a predetermined maximum fraction (αmax), c) determining an adjacent path (Ti+1) passing through the plurality of determined adjacent points, and d) iterating steps a) to c) using the adjacent path, defined as a new reference path, so as to determine, on each iteration, a new adjacent path, all of the adjacent paths thus determined defining the trajectory.