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this paper studies the software system of aluminum alloy welding power supply, improved the shortcomings of traditional PID control current, added PID parameters control based on ant colony optimization, realized PID parameter adaptive change and controlled the current waveform effectively. The Matlab / Simulink simulation analysis and technical verification were carried out, the results showed that, compared with the traditional PID control, the adjustment time of PID parameter control based on ant colony algorithm was reduced by 50%, i.e. 12.5 s, and the overshoot was only 2.5% and obviously less than the former, and the verification of additive manufacturing experiment showed that the current waveform was clear, the transition was smooth, and the appearance of aluminium alloy as-deposited part was good. The above results proved that the addition of ant colony algorithm could effectively control the welding current waveform.

In order to improve the stability of SPMIG welding process, this paper fully utilized the characteristics that sine wave was the low-frequency modulation signal as well as the sine wave function was derivable for any order to make the energy change dE/dt smooth, thus improving the welding stability and welding joint performance. The tests for the SPMIG and DPMIG welding of AA6061 aluminium alloy were carried out, respectively. Then the test results of two kinds of welding methods in instantaneous current waveform, weld appearance, U-I diagram, probability distribution of current and voltage, weld hardness, microscopic structure of welds, and so on were compared, and the superiority of SPMIG was verified.

This paper firstly introduced the principle and technological method of fuzzy self-tuning algorithm, and discussed related parameters and rules of the fuzzification, membership function, fuzzy rule and defuzzification in the fuzzy self-tuning algorithm. Then, two kinds of PID control methods were compared by the Simulink simulation platform, and the result showed that the input adaptability and anti-interference ability of fuzzy self-tuning controller of PID parameters were significantly better than those of fixed PID controller. Finally, the result was verified by the SPMIG welding test for aluminium alloy sheet with a thickness of 2mm, thus obtaining better welding effect.

Considering Considering double-wire pulsed MIG welding, the control method of sine-wave modulation has the advantage of high speeds in dual wire welding, strengthens the energy mixing transfer, forms the scales of the weld and reduces the bubble generation. The current research explores this control method to improve welding speed and welding quality. By introducing the amplitude coefficient k and the negative half-cycle sine wave pulse number Nn, this paper establishes the relationship between the parameters of sine-wave pulse-modulated double-wire MIG welding with common features, analyses the adjusting range of each parameter in the relationship, and employs an orthogonal test to analyse the effect of different modulation periods caused by different values of the negative half-cycle sine wave pulse number Nn on the welding of double-wire MIG with a sine wave pulse. The results indicate that when the value of the negative half-cycle pulse number Nn is 16, the energy coefficient k has an extensive value range, superior robustness and an ideal fish-scale pattern weld is feasible.

The high-speed double wire pulse metal-gas arc (MAG) welding process possesses advantages of automation and high efficiency and quality. Thus, it attracts much more attention nowadays. To meet the requirements of the double wire pulse MAG welding process, a novel double wire pulse MAG welding inverter integrated with technologies, such as soft-switching, double closed loop control, and synchronic control, is produced. A complete performance test was done for the pulsed MAG welding power supply by using a computer testing platform. The results of the experiment indicate that the novel welding inverter has an excellent performance both in the dynamic and the static characteristics. Also, the synchronic control between the master inverter and the slave inverter is reliable.

Magnetic field distribution model of tandem wire pulsed MIG high-speed welding was established, so was model of electromagnetic force on droplet. Through analyzing on parameters of the magnetic field of arc space, it was found that magnetic field intensity generated by arc and current were linear dependence, when current pulses of tandem wire were not overlapped, magnetic blow caused by parallel arc was minimum. Through analyzing on parameters of the model of electromagnetic force on droplet, it was found that the unit electromagnetic force on droplet and current product of the tandem wire were linear dependence, when the current pulses of tandem wire were not overlapped, the electromagnetic force on droplet was the least, and deviate distance of droplet trajectory was also minimum. Finally, contrast experiments of in-phase, random-phase and anti-phase current pulse were carried out by self-developed multifunctional tandem wire welding machine. The results indicated: when the current pulse of leading torch and tracking torch were not overlapped, the welding process was stable, and the weld was perfectly formed.

There are many kinds of aluminum alloys suitable for double-pulse MIG welding, however, the welding parameters are much more and they cannot be easily adjusted. Thus, it is necessary to establish the expert database for the welding source. In order to improve the adjustment performance to precisely control the welding current, this paper proposes a kind of expert database of unified parameter adjustment based on the long-step calibration and cubic spline interpolation to make the welding parameters “continuously adjusted” and “precisely matched” as well as make the test results verified.

The resolution problem of welding seam ultrasonic imaging system is studied in this paper, a triple-stage stepwise solutions is proposed, the measured ultrasonic signal is processed by super-resolution algorithm based on wavelet transform, signal processing result shows: the method is feasible to improve image quality of ultrasound imaging equipment and enhances its ability to identify subtle defects in welding seam. Moreover, the algorithms is under further improving and enhancing in ultrasonic image.

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.