Method for warm-forming square and rectangular tube by round tube on-line induction heating

The invention relates to a method for warm forming of a square and rectangular tube by on-line induction heating of a round tube, and mainly relates to a novel method for on-line heating of the formed round tube to a warm forming temperature interval through an induction heater and roll bending forming of the square and rectangular tube. Comprising the following steps: feeding a round pipe; switching on a water pump power supply to establish cooling water circulation of the induction heating power supply and the transformer; an induction heating power supply is turned on, the power of the induction heater is controlled by adjusting an oscillation power knob of the induction heating power supply, online heating is performed on the circular tube by adjusting the power, the coil is annularly arranged around the outer surface of the circular tube, and the square rectangular tube is finally formed through remaining passes after heating. On-line induction heating is conducted on the square and rectangular pipe form