The Application Of Transverse Magnetic Field In High-speed TIG Welding

With the application of the welding process in the industry, in order to strengthen their competition, manufacturers scream for the less cost and higher efficiency welding process. Appending magnetic field control on welding process is an advanced welding technology which is developing now. As plasma, welding arc has well electric character. Exterior magnetic field can affect shape and movement of welding arc. And the problems of the undercut and hump seam due to high-speed TIG welding can be well solved and advanced the productivity. Making good use of application of magnetic field can control welding process, The device can output AC and DC current and intermit alternative square wave pulse, and has many advantages such as small volume, simple circuit structure and high reliability. Its current amplitude, frequency duty cycle and alternative time can be adjusted continuously.The main circuit, control circuit and driving circuit of the developed device was studied and designed in the paper. The main circuit used the dual inverter structure. The SG3525A chip and the SG3526 chip were used respectively as PWM control chip for two inverter circuits. The corresponding driving circuit was designed. Soft -starting circuit is designed to overcome the surge current for protecting main switches. Test waveforms were measured when was installed and adjusted. Every waveform was analysed in the paper. The DC current is added to the new device compared to the old device, which only owns AC current. Magnetic head is designed by coaxial symmetrical with tungsten electrode. The insulation, cooling and hermetization of magnetic head avoid the influence on outside magnetic field; miniaturization design of magnetic head could achieve different welding process.Using the developed Magnetic-Controlling Device, intermittent alternative transverse magnetic field was applied in high-speed TIG arc bead welding. And the microstructure observation and flaring test were investigated, the test results show that applied transverse magnetic field can efficiently control welding arc, reduce welding gas feed rate from 0.7m3/h to 0.5 m3/h and welding current from 95A to 75A and increase welding speed from 3.5m/min to 5.5 m/min. Applying transverse magnetic field can improve the welding pattern and mechanical property.