Research On The Tracking Method Of CO₂ Gas Shielded Welding With Narrow Gap Based On Magnetron Arc Sensor

Advancing the intelligent and automation of welding is the objective requirement of modern industrial production. With the development of Chinese modern industrial process, the metal structures such as large pressure vessels, rails and other building components have been widely used in industrial field. During the production process, welding between the planks is a very important step. As a commonly used technique, CO₂ gas shielded welding with narrow gap is characterized by its small welding section, high wielding efficiency and excellent performance of joints, etc. However, there are few studies about the seam tracking technology which is based on this method.In this paper, a magnetic swing arc sensor was used for the seam tracking of CO₂ gas shielded welding with narrow gap. Its relevant theories were studied and analyzed in detail. Some essential problems were solved and a design of corresponding seam tracking system was presented. The results can be concluded as follows:（1）The influence of magnetic arc sensor’s parameters on arc movement was observed, and the effects of excitation frequency and excitation current on the weld width were also studied by simulating. Combined with the requirement of weld process for CO₂ gas shielded welding with narrow gap, an arc sensor control method which ensures the full integration of the two side walls was obtained. At the same time, an angle adjustment equipment was designed to assist the blending of side walls, which prepared the application of magnetic arc sensor on a narrow gap welding.（2）The basic theory of arc move in narrow gap was studied, and the different states of arc when located in various positions under the control of magnetic sensor during process of narrow gap welding were also studied. Besides, an equation that regarding the changes in arc length was established according to the relationship between welding torch and arc. Based on this mathematical model, a simulation analysis by using MATLAB was carried out and the law of arc movement was summarized..Furthermore, the variation law of current was also obtained through the correspondence between the arc length and welding current, which prepared the identification of deviation signal.（3）The characteristics of wavelet filtering method were researched. A simulation was carried out to select the appropriate wavelet basis and threshold. In addition, The stratified layers were determined by simulating to improve the filter method in CO₂ gas shielded welding with narrow gap.（4）A weld deviation recognition method was designed based on the change slope of current according to the current variation characteristics, and a pulse acquisition circuit was also projected to avoid unnecessary information. Meanwhile, a bias identification equation and an intelligent control method which related to magnetic field strength were established to adjust the arc swings. Moreover, an adjustment algorithm was designed and the core digital potentiometer was programmed.（5）For the purpose of verifying the proposed method of seam tracking, a seam tracking test was carried out according to the constructed seam tracking method about CO₂ gas shielded welding with narrow gap. The results showed that the tracking effect is obvious, and the magnetic field strength control system runs steadily.