Additive Manufacturing Process With Residual Stress Feedback

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Solution Overview

Problem

Laser-based additive manufacturing faces challenges with low energy efficiency and slow deposition rates, limiting its application potential and ability to build large parts due to small chamber sizes and high accuracy at the expense of speed.

Innovation Solution

A method involving powder characterization, in-situ inspection, laser processing, layer cleanup, and ultrasonic measurement to control residual stress, allowing for repeated deposition with stress reduction techniques when necessary, enabling higher deposition rates and larger volumes with closed-loop control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If small bead size with small layer buildup (20-100 μm thickness per pass) is used to achieve high accuracy, then manufacturing precision is improved, but deposition rate becomes very slow

Engineering Contradiction:
Improvelayer accuracyVSAvoiddeposition rate
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system dynamically adjusts layer thickness based on real-time monitoring of residual stress levels. When residual stress is low, thicker layers are deposited to increase productivity; when residual stress approaches thresholds, layer thickness is reduced or stress relief operations are inserted. This dynamic adaptation resolves the contradiction by making layer thickness a variable parameter rather than a fixed small value.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of layer thickness from a fixed small value (20-100 μm) to a variable parameter that can be adjusted based on residual stress conditions. By monitoring residual stress in real-time and adapting layer thickness accordingly, the system achieves both high precision (when needed) and high deposition rates (when conditions permit).

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If conventional laser based material deposition is used with small chamber sizes, then manufacturing precision is maintained, but the ability to build large parts is limited

Engineering Contradiction:
Improvecoating precisionVSAvoidpart size capability
Core Design Contradiction:
Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The system segments the manufacturing process into monitored zones and unmonitored zones, allowing different deposition strategies in different regions. Real-time residual stress monitoring is applied selectively to critical areas, while other areas can use faster deposition methods. This enables large part construction while maintaining precision where needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The residual stress monitoring system serves multiple functions: it guides layer thickness selection, determines when stress relief operations are needed, and enables both small and large part construction. This multi-functional approach allows the same system to maintain precision across varying part sizes and geometries.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If real-time residual stress monitoring and stress relief operations are implemented, then structural integrity is improved, but process complexity increases

Engineering Contradiction:
Improvestructural integrityVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system implements feedback control by monitoring residual stress levels in real-time and using this information to adjust subsequent deposition parameters or insert stress relief operations. This feedback mechanism ensures structural integrity while automating the decision-making process, reducing the need for complex manual intervention.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-diagnosis and self-correction by automatically monitoring residual stress and triggering appropriate responses (adjusting deposition parameters or performing stress relief). This self-service capability improves structural integrity while minimizing the need for external monitoring and control complexity.

Inventive Principle:
Principle #25Self-service

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 enhances deposition rates and volume capabilities, reduces production time from 30-40 hours to approximately 4 hours, and ensures structural integrity by managing residual stress, thus improving the efficiency and cost-effectiveness of additive manufacturing.

Implementation Method 1

inspecting via ultrasonic measurement process the laser processed powder materials to determine residual stress

Methodology Applied
Scientific EffectUltrasonic measurement: Ultrasound

Implementation Method 2

laser processing the powder materials

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 3

laser based material deposition has been used for precise coating deposition and for additive layer manufacturing

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP3558571B1Method of additive manufacturing of components
Publication Date: 2022.12.14 SIEMENS ENERGY INC
  • EP3558571B1 patent drawingFigure 1
  • EP3558571B1 patent drawingFigure 2~5
  • EP3558571B1 patent drawingFigure 6~9

AI summary

A method of additive manufacturing a component. The method includes selecting powder characterization, depositing powder materials, inspecting the powder materials, selecting process and laser parameters for laser processing, laser processing the powder materials, performing layer cleanup, determining stress state and relieving, additionally inspecting the laser processed powder materials, and repeating steps until a buildup of the component is complete.