High frequency pipe manufacturing control

1.The pipe weld gap control

Adjust the amount of squeezing rollers squeeze, so keep the flush weld ends, the opening angle of 7 degrees or less, the weld gap control between 1-3 mm. Weld control is too large, it may appear bad, weld cracking to produce incomplete fusion or weld control is too small, due to the excessive heat, likely to cause the weld burning, molten metal splash, build-up is too large, affecting the quality of welding . (Splatter causes: melt extrusion tube side, the internal pressure is greater than the surface of the weld steam pressure)

2.The high-frequency induction loop location

Place the induction loop should be in the same center line pipe, induction loop end from the squeeze roller centerline distance, squeeze rollers under the premise does not burn, depending on pipe size as close, too far away when the heat-affected zone width, weld strength will decrease. Coupled inductor coil tight as possible, the selection of a single lap, induction coil width should be equal to the pipe diameter. Use a single or double ring ring a great influence on the high-frequency oscillation frequency and output efficiency.

3.Impedance (also known as magnet) position control

Impedance is a set or a special magnet whose cross-sectional area 70% of the inner diameter steel pipe section. Its role is to strengthen the electromagnetic induction, eddy current centralized heat weld edges. Sometimes outside seam add some magnets, can also play a supporting role. Magnet’s temperature on the permeability greatly lower the temperature, the higher permeability. The magnet should be placed in the heating section V-zone, front roll center position in the extrusion, location and permeability of the magnet will directly affect the welding efficiency and weld quality.

4.The heat output control

High frequency power input to the heat pipe welds called heat input, less heat input welding speed is too fast, the tube can not reach the edge of the welding temperature, the formation of incomplete fusion or penetration of crack but excessive heat input When welding speed is too slow, prone to over-burning, the weld breakdown, causing splatter, to form pores. By adjusting the speed of the high-frequency voltage or welding methods to control the size of the heat input, the erw steel pipe welds not appear incomplete penetration without burn-through phenomenon occurs, to weld quality requirements.

Post time: Sep-11-2019