Modeling of Conduction Mode Laser Welding Process For Feedback Control

1999 ◽  
Vol 122 (3) ◽  
pp. 420-428 ◽  
Author(s):  
Fuu-Ren Tsai ◽  
Elijah Kannatey-Asibu,
Keyword(s):  
Feedback Control ◽  
Laser Welding ◽  
Weld Pool ◽  
Vision System ◽  
Plate Thickness ◽  
Welding Process ◽  
Laser Machine ◽  
Mode Laser ◽  
Conduction Mode ◽  
Laser Welding Process

The response of conduction mode laser weld pool dimensions, specifically weld width, to a step change in power input has been modeled using two-dimensional heat flow analysis. The goal is to develop a simplified model suitable for feedback control. The weld pool geometry was approximated by a tear-drop shape. The workpiece thermal properties were assumed to be lumped and temperature-independent. The result was a first-order weld pool thermal model. A series of experiments was performed using different welding conditions (plate thickness, step power changes, and welding speeds) to validate the model. The weld pool image was recorded using a vision system and digitized. The process time constant as calculated by the model was of the order of 10−4 seconds. The response of the laser machine, estimated by the least squares method, was found to be about 10−2 seconds, which is much slower than that of the weld pool. Thus, within the constraints of the assumptions on which the model is based, the entire laser welding process is considered to be dominated by the laser machine dynamics. [S1087-1357(00)00502-5]

Extraction of Weld Pool Width Feature Based on Visual Sensing during High-Power Fiber Laser Welding

2012 ◽  
Vol 201-202 ◽  
pp. 388-391
Author(s):  
Zi Qin Chen ◽  
Xiang Dong Gao
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
Weld Pool ◽  
High Power ◽  
High Speed ◽  
Welding Process ◽  
304 Stainless Steel ◽  
Fiber Laser Welding ◽  
Weld Pool Width ◽  
Laser Welding Process

In a high-power fiber laser welding process, the thermal radiation of a weld pool contains plenty of information for welding quality, in which the pool width can reflect the welding stability. Thus, extracting the welding pool width of high-power fiber laser welding based on infrared thermal imaging is an important method for monitoring the weld seam quality. In this paper, we studied the 304 stainless steel welded by a 10kW high-power fiber laser continuously. A near-infrared high-speed sensing camera was used to capture the weld pool images. Image algorithms such as median filtering, gray scale stretching, cutting, dynamic threshold mathematical morphology were applied to extract the weld pool image edge, analyze and detect the weld pool width. Welding experimental results showed that the proposed methods could extract the weld pool width, which could reflect the stability status of high-power fiber laser welding process accurately.

Numerical Analysis of Heat Transfer and Fluid Flow in Micro-Welding Using CFD

2018 ◽  
Author(s):  
Divyaj Shah ◽  
C. M. Sewatkar ◽  
Ketaki Godbole
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Laser Welding ◽  
Welding Process ◽  
Beam Intensity ◽  
Beam Radius ◽  
Governing Equations ◽  
Weld Depth ◽  
Conduction Mode ◽  
Laser Welding Process

Laser welding is used to join metals of small thickness. The heat affected zone in this process is very small and the temperature gradients encountered are very large (of the order of 104K/mm). We have used numerical methods to analyze the effect of various parameters. For the present study, an in-house C code was developed to model the laser welding process. A Finite Volume based discretization was done and a Semi-Explicit method was used to solve the governing equations. Conduction mode heat transfer was considered by assuming no vaporization of the molten metal. The effect of various parameters like beam intensity and beam radius were studied on the weld dimensions. The beam intensity was varied from 5.2KW to 15KW while the beam radius was varied from 0.14mm to 0.35mm. The effect of welding angle was also studied on the weld dimensions. The welding angles used for the study were 0°, 26.5°, 45° and 56°. It was found that the weld width and depth increased with an increase in beam intensity and a decrease in beam radius, while the weld depth decreased with an increase in welding angle. The change in heat transfer and fluid flow was also studied by varying these parameters.

Sign in / Sign up

Export Citation Format

Share Document