Huang Shi-sheng

Approximate entropy—a new statistic to quantify arc and welding process stability in short-circuiting gas metal arc welding

Based on the phase state reconstruction of welding current in short-circuiting gas metal arc welding using carbon dioxide as shielding gas, the approximate entropy of welding current as well as its standard deviation has been calculated and analysed to investigate their relation with the stability of electric arc and welding process. The extensive experimental and calculated results show that the approximate entropy of welding current is significantly and positively correlated with arc and welding process stability, whereas its standard deviation is correlated with them negatively. A larger approximate entropy and a smaller standard deviation imply a more stable arc and welding process, and vice versa. As a result, the approximate entropy of welding current promises well in assessing and quantifying the stability of electric arc and welding process in short-circuiting gas metal arc welding.

Fuzzy Control of Wire Feeder in Pulse Welding System

The paper presents a new method for the pulse welding, by which the arc welding power supply voltage is kept stable while the feeding speed is set to vary like a pulse, namely, to make the speedy feeding and low-speed feeding alternate. In the feeder, the couple closed-loop fuzzy control system is adopted for the wire-feeding speed control. In the inner closed-loop of the system, the adjustment is achieved with the motor current as the feedback signal while in the outer closed-loop the adjustment is achieved mainly by the actual speed of wire feeder as the feedback signal. The adjustment on rotating speed and the current relies on the fuzzy controller. Proven by the experiments, the feeder of such a kind is swift in system responding and when needed, the motor speed can be excellently steady. If the set signal is a pulse, the peak current and the base current alternate in the actual welding cases.

Key Techniques on Design of Laser High-speed Video System for Recording Metal Transfer in Arc Welding

The metal transfer process of arc welding with consumable electrode is a complicated procedure that combines momentum, heat and mass transfer as well as transportation. Due to the difficulties of observing fast changing process of melted drop transition, a proper high-speed video system with laser in the background was established for recording the process. Structure of the high-speed video system, design of optic system, selection of laser and preferences of camera lens which have influences on the recording results are introduced. The electrical waveforms and images of welding process were collected in synchronous with the system.