Design Of A Device For Generating Rotating Magnetic Field Used To Control Welding Arc

Append 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 welding bead and drops transfer can also be changed to improve the welding process and advanced the productivity.Conventional magnetic field form used in welding technology including horizontal magnetic field, vertical magnetic field and sharp-angled magnetic field, mainly excited by DC, AC and pulse excitation. Based on characteristics above, a new theory of"controlling movement by moving"is proposed, which means that controlling welding arc by moving magnetic field. A new device for generating rotating magnetic field is designed; magnetic head and excitation power source are included.Magnetic head is designed by six magnetic poles in symmetrical distribution, the design of excitation loop and excitation angle makes magnetic field act on welding arc region which could control welding arc effectively. The insulation, cooling and hermetization of magnetic head avoid the influence on magnetic field of outside; miniaturization design of magnetic head could achieve different welding process. The design of excitation power source based on principle of three phase step motor and pulse width modulation(PWM)technology, intelligent power model (IPM) is used for inverter switches, the output AC pulse used as excitation signals. The speed of rotation and magnetic intensity can be changed by regulate the exciting converted frequency and magnitude of exciting current. Constant current is achieved by closed loop feed back.By the test of three-dimensional distribution, form character, rotating frequency and magnetic field intensity of rotating magnetic field, it showed that the magnetic field produced is a highly rotating magnetic field and mainly distribute on welding arc region, rotating frequency and magnetic intensity can be regulated through excitation power source. Based on lots of TIG experiments, it can be concluded that welding arc can be well controlled, the characteristic of movement behavior of welding arc are gotten, which lay reliable guarantee on application of MIG/MAG welding technology.