Laser Weld Scanning Pattern for Uniform Heat Input
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Solution Overview
Problem
Conventional laser welding methods, such as those using Lissajous patterns, often result in non-uniform heat input due to varying drawing speeds, leading to inconsistent weld bead formation.
Innovation Solution
A laser welding method and device that control the drawing speed and output of the laser beam to maintain equal heat input per unit length in a continuous pattern where two annular patterns are in contact, ensuring uniform heat distribution across the entire pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a Lissajous pattern is drawn on the workpiece surface using conventional scanning methods, then welding can be performed at high speed, but the drawing speed varies significantly between linear and directional change regions, causing non-uniform heat input
Solution Approach 1:
The patent applies dynamics by making the laser beam oscillation frequency variable rather than constant. The frequency is dynamically adjusted based on the instantaneous drawing speed at each position in the scanning pattern, ensuring that the product of frequency and drawing speed remains constant. This dynamic adjustment compensates for speed variations in different regions of the Lissajous pattern, achieving uniform heat input while maintaining high welding speeds.
Solution Approach 2:
The patent changes the parameter of laser beam oscillation frequency to resolve the contradiction. By varying the frequency parameter according to the spatial position and drawing speed in the scanning pattern, the invention transforms the fixed-frequency approach into a variable-frequency approach, thereby achieving both high productivity and uniform heat input distribution.
2Loss of time
If the laser beam drawing speed is increased to improve productivity, then total welding time is reduced, but the heat input per unit length becomes non-uniform due to speed variations in different pattern regions
Solution Approach 1:
The patent uses dynamic frequency adjustment to maintain heat input consistency even at high drawing speeds. The oscillation frequency is continuously adapted to the instantaneous drawing speed, ensuring that the effective heat input per unit length remains uniform throughout the scanning path, thereby achieving both time efficiency and precision.
Solution Approach 2:
The patent implements a feedback mechanism where the oscillation frequency is determined based on the calculated instantaneous drawing speed at each position. This feedback loop ensures that speed variations are compensated in real-time, maintaining uniform heat input distribution while allowing high overall welding speeds that reduce total welding time.
3Productivity
If a continuous scanning pattern is used to maintain high welding speed, then productivity is improved, but the weld bead shape becomes unfavorable due to non-uniform heat input distribution
Solution Approach 1:
The patent applies dynamics by adjusting the oscillation frequency dynamically along the scanning path. This ensures that even in continuous high-speed scanning, the heat input per unit length remains uniform, which is critical for forming consistent and favorable weld bead shapes while maintaining high productivity.
Solution Approach 2:
The patent changes the oscillation frequency parameter as a function of position and drawing speed. This parameter modification ensures uniform thermal distribution during continuous scanning, enabling both high welding speeds and favorable weld bead morphology by preventing localized overheating or underheating.
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 the formation of a weld bead with a favorable shape by stabilizing heat input, maintaining consistent penetration depth and securing a process margin without narrowing the appropriate condition range of drawing speed and output.
Implementation Method 1
a laser beam having high power density... irradiating a surface of the workpiece with a laser beam
Data Source
AI summary
Provided is a laser welding method including a welding step of welding a workpiece by irradiating a surface of a workpiece with a laser beam that is swept two-dimensionally while being advanced in an X direction. In the welding step, the laser beam is swept to draw a predetermined pattern on the surface of the workpiece. Additionally, drawing speed and output of the laser beam are controlled to have an equal amount of heat input per unit drawing length in the predetermined pattern over the entire length of the predetermined pattern. The predetermined pattern is a continuous pattern in which two annular patterns are in contact with each other at one point.