Additive Manufacturing Toolpath Corrections for Local Heat Control
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Solution Overview
Problem
Additive manufacturing processes face challenges with overheating and defects in structures due to localized heat generation, particularly in thin-walled or overhanging sections, leading to increased stresses, strains, and potential damage from enlarged molten beads.
Innovation Solution
A method that calculates local and global heat generation in additive manufacturing, determining process control corrections by assigning corrective measures to individual vectors of the energy beam's toolpath, using mass integrals to assess thermal behavior and reduce energy input, thereby controlling melt pool size within defined tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard process parameters are used for additive manufacturing, then manufacturing efficiency is maintained, but localized overheating occurs in thin-walled or overhanging sections leading to defects
Solution Approach 1:
The patent applies local quality by differentiating process parameters based on local geometric characteristics. The system calculates a mass integral for each vector of the toolpath, representing the local amount of material surrounding the energy beam's path. Based on this local mass assessment, the laser power is dynamically adjusted - reducing power in regions with insufficient surrounding material (thin-walled or overhanging sections) to prevent overheating, while maintaining standard power in well-supported regions. This localized parameter adaptation resolves the contradiction between maintaining manufacturing efficiency and preventing localized overheating defects.
2Manufacturing precision
If comprehensive simulation and corrective measures are implemented for every vector, then manufacturing precision improves, but computational effort and processing time increase
Solution Approach 1:
The patent applies segmentation by dividing the toolpath into individual vectors and calculating the mass integral independently for each vector. This segment-by-segment approach allows the system to process only the necessary information for each small segment rather than performing comprehensive simulations on the entire structure. The mass integral calculation for each vector provides sufficient local thermal behavior assessment, enabling efficient determination of corrective measures without requiring exhaustive computational resources, thus resolving the contradiction between precision and processing time.
3Manufacturing precision
If energy beam power is reduced in critical areas, then overheating and defects are prevented, but manufacturing productivity decreases
Solution Approach 1:
The patent applies dynamics by making the laser power dynamic rather than static. The system calculates the mass integral for each vector and determines the required laser power dynamically based on the local thermal behavior assessment. This dynamic power adjustment ensures that energy input is optimized for each specific location - reduced where necessary to prevent defects, and maintained at higher levels where conditions permit faster processing. This dynamic adaptation resolves the contradiction between defect prevention and manufacturing speed by allowing both objectives to be achieved through location-specific parameter optimization.
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 minimizes computational effort while improving component quality by reducing overheating, stresses, and strains, preventing defects, and ensuring seamless process control with minimal computational resources.
Implementation Method 1
a laser beam 17, which, by means of an optical deflection device with a mirror 18, passes through the window 12a into the process chamber 12 and moves across the surface of the powder bed 13. The powder is melted at the point of impact of the energy beam 17
Implementation Method 2
Heating devices 23a in the form of electric resistance heaters (alternatively, induction coils are also possible, not shown) are provided in the housing 22 and the build platform 20. These heaters can preheat the workpiece 19 being formed and the particles of the powder bed 13.
Implementation Method 3
The surface temperature of the powder 13 can be determined by a thermal imaging camera 27 in order to adjust the heating power of the heating devices 23a, 23b as needed.
Data Source
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AI summary
The invention relates to a method for determining building instructions which describe the control of a process and which can be used in an additive manufacturing system (11) for an additive manufacturing method. A manufacture data set PAR is generated in order to produce the building structure in layers (25). A global heat development and a local heat development are taken into consideration. According to the invention, correction parameters are loaded from a database F on the basis of the global heat development, said correction parameters being assignable to locally individual vectors of a tool path as correction measures for controlling the process. The tool path defines the path which the energy beam (17) follows on the surface of the powder bed (13). The invention additionally relates to a method for determining correction parameters PAR for controlling the process in an additive manufacturing system (11). According to the invention, this is achieved in that the local heat development in the surroundings of the heat input of the energy beam (17) is calculated. The correction measures are derived from the heat development and are stored in a database F. The advantage of using both methods consists in that a precise simulation is only required in the mesoscale range and can already be carried out ahead of a manufacture preparation for the component (19). If the geometry of the component (19) is known, then only a macroscale simulation must be carried out in order to define the global heat development. Thus, the computing complexity of the simulation decreases significantly such that the modified method parameters PAR1 can be easily found. The invention also relates to a storage format for the modified data and to computer program products for storing the programs.