Electron Beam Layer Manufacturing With Closed-Loop Molten Pool Control
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Solution Overview
Problem
Existing layer manufacturing (LM) processes using electron beams for melting metals operate in an open loop fashion, relying heavily on human intervention for adjusting operating parameters, which is subjective and prone to errors.
Innovation Solution
The implementation of a closed loop control system that monitors molten pool deposits using overhead imaging and a cooled camera housing, along with a vapor protective device, to automatically adjust processing conditions based on real-time data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If camera-based monitoring systems are used to control metal deposition using overhead imaging, then manufacturing precision and automation are improved, but the system becomes susceptible to vapor build-up that corrupts images and distorts pixels
Solution Approach 1:
A purge gas flow is introduced as an intermediary medium between the molten metal pool and the camera optics. The gas flows across the optical path to prevent vapor from reaching and contaminating the camera lens and sensors, thereby maintaining image quality without compromising the monitoring function
Solution Approach 2:
The harmful vapor is extracted from the optical path by directing the purge gas flow to capture and remove vapor before it can reach the camera. This separates the monitoring system from the harmful environment of the molten metal pool
2Productivity
If camera electronics operate at high speeds to capture rapid imaging for closed loop control, then productivity and response time are improved, but heat generated by the electronics corrupts the obtained images
Solution Approach 1:
A cooled barrier or purge gas flow acts as an intermediary between the hot camera electronics and the molten metal pool. This barrier prevents thermal radiation and conduction from corrupting the images while allowing the high-speed electronics to operate at optimal temperatures
Solution Approach 2:
The patent replaces passive thermal management with an active cooled barrier system that actively removes heat from the optical path, enabling high-speed imaging without thermal corruption
3Adaptability or versatility
If an operator visually observes the LM process throughout the layer by layer buildup and manually adjusts parameters, then adaptability to process variations is improved, but the process becomes slow and prone to errors
Solution Approach 1:
A closed-loop feedback system is implemented where the camera continuously monitors the molten metal pool characteristics, and the control system automatically adjusts deposition parameters based on real-time image analysis. This replaces manual observation with automated feedback control, maintaining adaptability while dramatically increasing speed and reducing errors
Solution Approach 2:
The system performs self-adjustment through automated image analysis and control algorithms that modify deposition parameters without human intervention. The process monitors and corrects itself in real-time, eliminating the need for slow manual adjustments
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 enables more precise control of the LM process, reducing reliance on human operators and improving the consistency and quality of three-dimensional article fabrication, particularly at high output rates.
Implementation Method 1
an energy emission device for emitting energy to melt the raw material
Implementation Method 2
a detector that monitors a condition of the deposited material
Data Source
AI summary
A process and apparatus for free form fabrication of a three-dimensional work piece comprising (a) feeding raw material in a solid state to a first predetermined location: (b) depositing the raw material onto a substrate as a molten pool deposit under a first processing condition; (C) monitoring the molten pool deposit for a preselected condition; (d) comparing information about the preselected condition of the monitored molten pool deposit with a predetermined desired value for the preselected condition of the monitored molten pool deposit; (e) solidifying the molten pool deposit; (f) automatically altering the first processing condition to a different processing condition based upon information obtained from the comparing step (d); and repeating steps (a) through (f) at one or more second locations for building up layer by layer a three-dimensional work piece. The apparatus is characterized by a detector that monitors a preselected condition of the deposited material and a closed loop electronic control device for controlling operation of one or more components of the apparatus in response to a detected condition by the detector.