Molten Pool Depth Estimation via Thermal Imaging
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Solution Overview
Problem
The depth of the molten pool in 3D printing, particularly during the direct energy deposition method, cannot be directly measured, which affects the tensile strength of printed parts and is crucial for determining lamination quality.
Innovation Solution
A method and apparatus using a thermal imaging camera to measure the surface temperature of the molten pool, determining its boundary, length, and width, and estimating the maximum depth in real-time by analyzing temperature distribution equations, with a calculation unit to verify the estimated depth against actual measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement methods are used for molten pool depth, then measurement precision would be improved, but the method is not applicable because the molten pool depth cannot be directly measured
Solution Approach 1:
The patent uses thermal imaging camera to capture temperature distribution as an intermediary measurement. Instead of directly measuring the hidden depth parameter, the system measures the accessible surface temperature field, which serves as a mediator to infer the molten pool depth through thermal conduction relationships and heat transfer modeling.
Solution Approach 2:
The patent replaces direct physical measurement methods with thermal field-based indirect measurement. By substituting mechanical or direct probing methods with thermal imaging and heat transfer analysis, the system can non-contactly estimate depth parameters that are otherwise inaccessible to direct measurement tools.
2Manufacturing precision
If real-time monitoring of molten pool depth is implemented, then manufacturing precision would be improved, but device complexity increases due to thermal imaging and calculation requirements
Solution Approach 1:
The thermal imaging camera serves multiple functions: it captures temperature distribution for depth estimation, provides real-time monitoring capability, and enables quality control assessment. The calculation unit performs both depth estimation and verification against predetermined ranges, making the system multi-functional despite the added complexity.
Solution Approach 2:
The system uses the thermal field information from the printing process itself to perform self-monitoring and self-control. The temperature distribution data, which is naturally generated during laser melting, is reused for depth estimation without requiring separate measurement systems or additional energy input.
3Measurement precision
If thermal imaging is used to measure surface temperature, then the ability to estimate depth is improved, but loss of time occurs due to temperature measurement and calculation processing
Solution Approach 1:
The thermal imaging camera continuously captures temperature distribution during the printing process, and the calculation unit continuously estimates depth in real-time. This continuous monitoring eliminates idle measurement intervals and maintains uninterrupted depth estimation throughout the molten pool formation process.
Solution Approach 2:
The system uses temperature distribution data captured during the printing process to perform depth estimation before the molten pool solidifies. By conducting the measurement and calculation while the molten pool is still in its liquid state and thermally active, the system captures the most relevant thermal signatures for accurate depth estimation.
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 real-time estimation and detection of depth abnormalities in the molten pool, preventing defective products by ensuring the depth is within a predetermined error range, thus improving the quality and reliability of 3D printed parts.
Implementation Method 1
measuring a surface temperature of the molten pool by taking a thermal image of an area of a laminated printing object including the molten pool
Implementation Method 2
a laser beam irradiated from a laser source is irradiated to the substrate, and metal powder is supplied onto the molten pool
Implementation Method 3
applying laser energy to metal powder or wire material to be melted and fused
Data Source
AI summary
Disclosed are a method and apparatus of estimating a depth of a molten pool formed during a 3D printing process, and a 3D printing system. A surface temperature of the molten pool is measure by taking a thermal image of a laminated printing object during the 3D printing process with a thermal imaging camera. The measured surface temperature is compared with a melting point of the base material to determine a surface boundary of the molten pool. The maximum lengths in x-axis and y-axis directions of a surface region of the molten pool defined by the surface boundary of the molten pool are determined as a length and a width of the surface of the molten pool, respectively. A maximum depth in the z-axis direction of the molten pool is determined in real time based on the length and width of the surface region of the molten pool.