Abstract: A method of flash-butt welding in which the travel speed (Vt) of the machine mobile plate and the welding voltage (U2) are changed (by preset programs) and the travel speed is controlled through negative feedback by welding current, the voltage being changed discretely for each flashing fixed interval of tm duration as a function of the increment of the actual average speed of flashing details of shortening (Va) during the previous flashing interval, Va value being maintained at the present level, lower than Vm. The invention envisages a change of the coefficient of enhancement of the negative feedback in a discrete manner for each preset flashing interval of tm duration as a function of Va increment during the previous flashing interval.

Abstract: The apparatus comprises a current transformer coupled to the welding tranrmer primary and connected with an analog transmitter of the welding current and with a digital transmitter of the duration of short-circuits in the welding circuit, having a memory element at the output.

Abstract: The primary winding of a welding transformer is provided with controlled rectifiers and the primary winding of a current transformer. The secondary winding of the current transformer is connected to a welding current pick-up. The phase angle of opening of the controlled rectifiers is varied through a phase shifter and a programmer. A pulse shaper is provided for shaping pulses synchronized with the voltage of a supply circuit and has an output connected to a phase delay unit. An OR circuit is provided having inputs connected to the output of the welding current pick-up and to one output of the programmer, and an output connected together with the output of the phase delay unit through AND logical circuits and an inverter to the inputs of a voltage switching flip-flop having outputs each being connected in pair with another output of the programmer through additional AND circuits to corresponding inputs of the phase shifter.

Abstract: A machine for continuous flash butt welding comprises control devices for the control of beginning-of-upset operation and upset value, respectively, and such control devices are provided in one unit (a computer). Also provided are a control device for automatically controlling the flashing-off speed and a welding current meter connected to a welding transformer. A sensor connected to the meter detects short-circuit duration in the welding circuit in response to outputs of a welding control enabling signal generator actuated at the final stage of flashing and in the course of upsetting. The inputs of the latter are coupled to the computer and the output is connected to an upset value deviation control circuit. The latter receives inputs from a circuit which detects slippage of the parts in the clamping jaws during welding. The upset value deviation control circuit is further connected to a sensor means for detecting misalignment of a rod of the follow-up slide valve relative to its body.

Abstract: The invention relates to a device for welding workpieces that have a large cross-sectional area, as well as for cases of high welding power requirements. The device in accordance with the invention comprises a mechanism for continuously displacing the workpieces being welded with a controlled drive, a mechanism for imparting to the workpieces additional reciprocating motion, a welding transformer, and a means for controlling the speed of the drive. The drive speed control means includes a welding-current pulse shaper coupled to the output of a current transformer, the latter being included in the primary circuit of the welding transformer and a welding-current pulse-length setter. The latter and the output of the pulse shaper are coupled to a comparator, the output whereof is coupled to the drive control circuit.