1) Program-controlled reduced voltage flash butt welding is characterized in that a higher secondary no-load voltage is used at the beginning of the flash to facilitate the excitation of the flash. The flash speed is unchanged to improve thermal efficiency. When approaching upsetting, increase the secondary voltage to make the flash stronger to increase the self-protection effect.
Compared with preheating flash butt welding, program-controlled reduced voltage flash butt welding has the advantages of short welding time, low power consumption and uniform heating.
2) The characteristic of pulse flash butt welding is that during the feeding stroke of the movable clamp, a reciprocating vibration stroke is superimposed through the hydraulic vibration device, the amplitude is 0.25-1.2mm, and the frequency is 3-35Hz, which can be uniformly tune. Due to the vibration, the end faces of the weldment are alternately short-circuited and pulled apart, resulting in a pulsed flash.
Compared with ordinary flash butt welding, because there is no spontaneous blasting of the lintel, the sputtered particles are small and the crater is shallow, so the thermal efficiency can be more than doubled, and the upsetting allowance can be reduced to 2/3-1/ 2.
The above two methods are mainly to meet the needs of flash butt welding of large-section workpieces.
3) Rectangular wave flash butt welding Compared with the power frequency AC sine wave flash butt welding, this welding method can significantly improve the stability of the flash. Because the sine wave power supply will interrupt the flash momentarily when the voltage is close to zero, while the square wave can produce the flash evenly in the whole cycle. Independent of voltage phase.
The number of flashes per unit time of the rectangular wave power supply is 30% higher than that of the power frequency AC, the sprayed metal particles are fine, the fire port is shallow, and the thermal efficiency is high. The rectangular wave frequency can be adjusted in the range of 30-180Hz. This method is mostly used for continuous flash butt welding of thin plates and aluminum alloy wheels.
