Abstract
In process of AC square wave submerged arc welding, electric signal waveform determines the arc energy characteristics in the time and frequency domain, which also reflects the arc stability of welding process and quality indirectly. Using Wigner-Ville distribution (WVD), time frequency analysis is conducted to the current signal of AC square wave submerged arc welding. The Pseudo Wigner-Ville and smoothed Wigner-Ville distribution are discussed separately to suppress the cross-term interference. The numerical results indicate that the Choi-Williams kernel function has much superiority for time frequency analysis of the submerged arc welding electric signal. It can effectively suppress cross-term and eliminate noise in the Wigner-Ville distribution of welding electric signal, as well as owing the ability to portray the local feature of arc energy in AC square wave submerged arc welding.
Highlights
The AC square wave submerged arc welding is suitable for the ring seam welding, multi-arc welding and other special occasions because of the advantages of quick speed of crossing arc zero, non-magnetic blow and high welding deposition rate [1,2]
In the actual welding process, the arc space and the electrode surface temperature change versus time during the alternating positive and negative polarity of arc [3,4], the arc resistance is not constant and changes as the arc current changes, and the welding power supply source interfered by the electric characteristic and the external factors
Wigner-Ville timefrequency distribution (WVD) is a basic and most widely used timefrequency distribution.WVD is secondary time-frequency distribution that can obtain the instantaneous energy, frequency and power spectral density of signal, which is a powerful tool for analysis of non-stationary and time-varying signal
Summary
The AC square wave submerged arc welding is suitable for the ring seam welding, multi-arc welding and other special occasions because of the advantages of quick speed of crossing arc zero, non-magnetic blow and high welding deposition rate [1,2]. Since the arc electric signal of submerged arc welding is a multicomponent signal, it has a serious cross-term on WVD time-frequency analysis.
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