Study On The Technology And Process Of High Speed Welding With Sine Wave Modulated Pulse MIG

Pulse-Tandem MIG welding technology is widely recognized as one of the main ways to improve the welding speed and enhance the production efficiency.Currently,welding technology develops with the absence of independent products as is caused by the big gap between the development of twin-wire high-speed welding equipment home and abroad.In addition to the dissatisfactory effectiveness of intelligent control algorithm,high-speed welding also presents various defects such as incomplete penetration,lack of fusion and poor weld seam formation.To solve these problems,the current research,based on the traditional Pulse-Tandem MIG welding technology,investigates sine wave modulating pulse MIG twin-wire high-speed welding method and attempts to design an integral parameter online self-adaptive control algorithm applicable to pulse welding current control.The research is an in-depth and systematical research on the improvement of weld speed,weld quality and the increase of instantaneous weld power input.The current paper mainly discusses the following issues.(1)In order to avoid the blind design of integrated Tandem welding power supply,Simulink was used first to build the system simulation model that includes the main circuit,input and output module,control module and PID control module,which were then used to carry out the simulation analysis.Based on the simulation,the design scheme of integrated Tandem arc welding power supply based on DSP was designed,A single high-performance control core was directly applied to integrate two finite bipolar soft-switching main circuits to generate control signals,and the cooperative communication problem in Pulse-Tandem current-phase adjustment was solved effectively.(2)To overcome the shortcomings of classical PID algorithm in welding waveform control and to quickly adapt to the current signal of different welding specifications,an integral parameter online self-adaptive control algorithm applicable to pulse welding current control was proposed and the algorithmic controller was designed accordingly.Experimental result proves that the proposed integral parameter online self-adaptive control algorithm helps to realize the fast adjustment of pulse welding current integral parameter online with various welding conditions to obtain optimal technical parameters and ensure stable welding.The algorithm actualizes the speedily discovery of appropriate PI parameter and removes the dependency on the expert database,which significantly reduces amounts of previous experimental workload and enhances power performance and intelligent level.(3)On the basis of Tandem pulsed MIG welding technology,a new Tandem pulsed MIG welding sine wave modulation method is proposed to control the mathematical parameters of the current waveform parameters.The revolutionary analysis of mathematical relationship proves that the proposed mathematical model is widely applicable,and the mathematical connotation and control significance of various parameters were concluded as well.Experimental results show that based on sine wave modulation,the new technical method helps to enhance the precise control ability of tandem high-speed welding energy input and improves the stationarity of twin-wire globular transfer and the effectiveness of molten pool agitation.It also helps to reduce pore occurrence and structure scale weld seam formation,which effectively improve twin-wire welding speed and welding quality.(4)Sample entropy algorithm was used to analyze the influence of various electrical signal parameters on welding stability,including twin-wire welding electrical signal frequency,duty ratio and current probability density.The biggest influencing factor on welding quality was used as quantitative evaluation index of twin-wire stability.Weld seam fuzzy evaluation model was integrated to evaluate welding quality in terms of weld seam defect measurement.Support vector machine algorithm was then used to realize the multiple information fusion of the evaluation result.Eventually the qualitative evaluation of twin-wire high-speed welding quality was actualized.(5)Based on the mathematical model of the sine wave modulation method of the pulse-tandem MIG welding,the simplified relation formula was established for the amplitude coefficient k of the sinusoidal current,the pulse number Nn of the negative half cycle and the density coefficient m of the energy distribution.Orthogonal experiments were carried out to optimize these three parameters.The experimental results show that,first,the magnitude of the current amplitude coefficient k affects the depth of the fish scale,and is related to the current distribution density and energy distribution of the welding process,which can help to widen the energy gap between the positive and negative cycles and to realize the precise energy control.Second,the effect of the pulse number Nn on the weld quality in the negative half cycle is greater than that of the amplitude coefficient k,as it affects the density of the fish scale figure on weld seam surface.Third,the energy distribution system m is similar to the current amplitude coefficient k.(6)With the precondition of control parameter optimization,orthogonal experiment was carried out to make a comparative study with traditional pulse-tandem MIG welding in terms of welding speed and welding quality.Based on the analysis of weld seam formation,current waveform diagram,X-ray nondestructive testing and the weld metallographic,it was concluded that under the same welding condition,sine wave modulated pulse MIG twin-wire high-speed welding has higher welding speed and metal hardness as is formed in the molten pool area.It also causes lower metal brittleness in the heat-affected zone and produces desirable scale weld seam to ensure better welding quality.Accordingly,sine wave modulated pulse MIG twin-wire high-speed welding has various advantages over the traditional method such as better robustness,higher instantons current,wider energy adjustment range,higher welding speed and better welding quality.(7)Based on the sine wave modulated pulse MIG twin-wire high-speed welding,the current paper discusses as well the transition current waveform control.Result of orthogonal test shows that the additional employment of transition current waveform control is effective in improving welding speed in comparison with the use of traditional pulse-tandem MIG welding.It helps to form weld seam with higher score in technical performance evaluation and has better performance in metallographic analysis.