Electron Beam Layer Manufacturing Closed Loop Control
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Solution Overview
Problem
Existing layer manufacturing techniques using electron beams for melting metal often rely on open loop systems that require human intervention, leading to subjectivity and inefficiencies, particularly at high output rates, and lack effective deposition condition monitoring.
Innovation Solution
A closed loop control system utilizing the same electron beam generator for both melting and monitoring, detecting electron phenomena to adjust power and parameters in real-time, allowing for automatic alteration of processing conditions and reducing system size and components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop control with human intervention is used, then system complexity is reduced, but productivity and reliability deteriorate due to subjectivity and delays
Solution Approach 1:
The patent implements closed loop control by detecting electron phenomena (such as secondary electron emission, backscattered electrons, or bremsstrahlung radiation) from the melt pool and using this information to automatically adjust electron beam parameters. This feedback mechanism eliminates human intervention delays and subjectivity, enabling real-time optimization of deposition conditions while maintaining high productivity
Solution Approach 2:
The system uses the electron beam interaction phenomena itself as the monitoring signal source, where the melt pool's electron emission characteristics provide automatic process feedback. This self-monitoring approach eliminates the need for separate sensing systems, reducing complexity while enabling autonomous control adjustments
2Measurement precision
If separate monitoring equipment is added for closed loop control, then deposition condition monitoring improves, but device complexity increases
Solution Approach 1:
The electron beam serves dual functions: it acts as both the processing tool (melting and depositing material) and the monitoring probe (generating detectable electron phenomena from the melt pool). This multi-functionality eliminates the need for separate monitoring equipment, reducing system complexity while maintaining precise deposition condition monitoring
Solution Approach 2:
The patent uses electron phenomena (secondary electrons, backscattered electrons, or bremsstrahlung radiation) as an intermediary signal that carries information about melt pool conditions. These electron-based signals naturally arise from beam-material interaction and provide precise monitoring data without requiring external sensing systems
3Device complexity
If human operators visually monitor the process, then system cost is reduced, but measurement precision and reliability worsen
Solution Approach 1:
The patent replaces human visual monitoring with electronic detection of electron phenomena. The detection system measures physical electron signals (secondary electron emission, backscattered electrons, or bremsstrahlung radiation) that directly correlate with melt pool conditions, providing objective, precise, and repeatable measurements free from human subjectivity
Solution Approach 2:
The system monitors changes in electron emission parameters (intensity, energy distribution, or angular distribution of emitted electrons) that directly reflect melt pool temperature, velocity, and composition. These physical parameter changes provide continuous, quantitative feedback for precise process control
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 rapid and accurate layer manufacturing with high output rates, reducing reliance on human operators and improving deposition control, resulting in efficient fabrication of complex three-dimensional articles.
Implementation Method 1
an electron beam generator for emitting an electron beam to melt a raw material
Implementation Method 2
monitoring the molten pool deposit by use of detection of one or more electron phenomena that occurs from emission from the electron beam generator
Data Source
Figure 1A
Figure 1B~1C
Figure 2~3
AI summary
A process and apparatus for perfoming the process for layer manufacturing a three-dimensional work piece comprising the steps of feeding raw material in a solid state to a first predetermined location; exposing the raw material to an electron beam (12) to liquefy the raw material; depositing the raw material onto a substrate (16) as a molten pool deposit, the deposit having a forward edge region in an x-y plane with a forward edge region width and a trailing edge region in the x-y plane with a trailing edge region width under at least one first processing condition; monitoring the molten pool deposit for at least one preselected condition using detecting of scatter from a scanning electron beam (12) contemporaneously with the depositing step; solidifying the molten pool deposit; automatically altering the first processing condition to a different processing condition based upon information obtained from the comparing step; and repeating steps at one or more second locations for building up layer by layer, generally along a z-axis that is orthogonal to the x-y plane, a three-dimensional work piece.