Laser Beam Wobbling in Metal Powder Deposition for Dilution Control
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Solution Overview
Problem
Current laser metal deposition (LMD) processes face limitations in achieving faster deposition rates, enhanced process control, stability, and flexibility, particularly in controlling dilution and heat input, which can result in defects such as residual stress and deformation.
Innovation Solution
The implementation of a system and method that uses a fiber laser with a wobbler module to wobble the laser beam in specific axes, combined with a focus lens and powder nozzle, allowing for precise control of the focal point location below the workpiece surface, enabling faster deposition rates and improved process stability by adjusting the wobble pattern, amplitude, and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional laser metal deposition is used, then metal powder can be deposited onto substrate, but deposition rate is limited and process control stability is insufficient
Solution Approach 1:
The patent applies laser beam wobbling (vibration) to oscillate the laser beam within the melt pool. This mechanical vibration of the energy source prevents hot spot formation, distributes heat more uniformly, and stabilizes the deposition process, thereby increasing both deposition rate and process control stability simultaneously
Solution Approach 2:
The patent implements periodic wobbling of the laser beam through controlled oscillation at specific frequencies. This periodic action creates cyclic melting and solidification patterns that enhance powder absorption, control dilution, and maintain process stability while achieving higher deposition rates
2Productivity
If high laser power is used to increase deposition rate, then productivity improves, but heat input increases causing residual stress and deformation
Solution Approach 1:
The laser beam wobble mechanically vibrates the energy input within the melt pool, preventing localized heat accumulation (hot spots) that would otherwise require higher overall laser power. This distributes thermal energy more evenly, enabling high deposition rates while controlling total heat input to minimize residual stress and deformation
Solution Approach 2:
The patent changes the spatial distribution parameter of laser energy by implementing beam oscillation with specific amplitudes and frequencies. This parameter change allows the same laser power to produce more uniform heating, increasing deposition efficiency while reducing harmful thermal effects like residual stress and distortion
3Manufacturing precision
If laser beam is focused at surface level, then deposition can occur, but dilution control is poor and heat affected zone is large
Solution Approach 1:
The wobbling laser beam mechanically oscillates within the melt pool, creating a dynamic heating pattern that confines heat more effectively. This vibration prevents excessive heat diffusion into the substrate, reducing the heat affected zone while improving control over material dilution through enhanced powder absorption efficiency
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 significantly increases deposition rates, enhances process stability, reduces residual stress and deformation, and optimizes dilution control, leading to higher quality metal powder deposition with reduced heat affected zones and the need for post-weld heat treatment.
Implementation Method 1
a fiber laser configured to generate a laser beam... a focus lens that is not a scanning lens and is configured to focus the collimated laser beam, the focused collimated laser beam directed through a powder nozzle device such that a focal point location of the focused collimated laser beam is positioned below a workpiece surface, the powder nozzle device configured to deliver metal powder to a region on the workpiece surface that is heated by the focused collimated laser beam
Implementation Method 2
a wobbler module having first and second movable mirrors, the first and second movable mirrors being approximately the same size and configured to receive the collimated laser beam from the collimator and to wobble the collimated laser beam in first and second axes within a scan angle of about 0.1-2°
Implementation Method 3
LMD is an additive technique that involves using a laser beam to form a pool of melted metal (a melt pool) on the surface of a metallic substrate into which metal powder is impinged via a gas stream. The metal powder is absorbed into the melt pool (i.e., melts and bonds with the base material) and generates a deposit on the surface of the substrate
Implementation Method 4
using a laser beam to form a pool of melted metal (a melt pool) on the surface of a metallic substrate
Data Source
AI summary
A method and system for laser metal powder deposition using beam wobbling. The system may include a fiber laser configured to generate a laser beam and a laser head, the laser head configured to receive the laser beam from the fiber laser and including a collimator configured to collimate the laser beam, a wobbler module having first and second movable mirrors, and a focus lens configured to focus the collimated laser beam through a powder nozzle device such that a focal point location of the focused collimated laser beam is positioned below a workpiece surface. The powder nozzle device delivers metal powder to a region on the workpiece surface that is heated by the focused collimated laser beam.