| 摘要 |
The invention relates to the field of welding, or more precisely - to the method of power supply of single-phase contact butt welders of alternating current. In a method of power supply of the single-phase spot-welding machines of alternating current for power supply of arc welding transformer intended for frequency F, by means of two three-phase two-period controlled rectifiers, which are opposite-parallel connected, voltage is formed with frequency of 3F/4. Each half-wave of voltage is formed by successive commutation of two line voltages, in this case the half-wave of one polarity begins by commutation of the same line voltage, on which the previous half-wave of another polarity is finished. The method provides for powering spot-welding machines for flash welding from three-phase electrical network, which have a single-phase transformer. The pulse shape of obtained voltage contributes to the formation of high quality welded connection, because its coefficient of amplitude Kis less than at welding by sinusoid current. The selected sequence of switching on of line voltage at beginning and end of each half-wave ensures reliable power supply, and in the majority of cases practically smooth curve of welding current. In the case three phases of the electrical network of power supply of welding sets are loaded evenly. |
