In situoptical measurement of liquid drop surface tension in gas metal arc welding

Abstract

The surface tension of detached liquid drops in pulsed gas metal arc welding was determined in situ from the period of the prolate-oblate oscillations initiated by the detachment event. The oscillating drops were imaged by an optical shadowgraph technique utilizing laser illumination. Images obtained during the welding process were recorded with a high-speed video camera and stored for subsequent analysis. For 4047 aluminium alloy wire, surface tension values in the range 0.54-0.7 N m −1 were obtained for various droplet sizes.

A laser back-lighting based metal transfer monitoring system for robotic gas metal arc welding

“…Since all the captured images comply with the model of Eqs. (7) and (8), thus the qualitative results are adequate to evaluate the accuracy.…”

“…Compared to the past research [7][8][9][10], the simplified system is costeffective and easy to be handled in real welding environments. The proposed monitoring system is capable of robustly extracting the metal transfer information on line with the proposed automatic and efficient image processing algorithms while this important capability was not addressed by the past research [7][8][9][10].…”

“…To better understand and control GMAW process, the metal transfer process has been studied widely. A lot of metal-transfer sensing methods have been proposed [1][2][3][4][5][6][7][8][9][10]. In [7], a technique named as laser back-lighting is proposed to image the metal transfer with good quality and contrast.…”

“…In [7], a technique named as laser back-lighting is proposed to image the metal transfer with good quality and contrast. This back-lighting technique has been adopted by many other researchers to conduct metal transfer research [8][9][10]. In [8], the back-lighting apparatus is used to determine the surface tension of the metal transfer droplets.…”

“…This back-lighting technique has been adopted by many other researchers to conduct metal transfer research [8][9][10]. In [8], the back-lighting apparatus is used to determine the surface tension of the metal transfer droplets. In [9], the back-lighting apparatus is used to image and classify the metal transfer modes by setting different welding parameters.…”