Manufacturing control of high frequency welded pipe

1. Pipe gap control
Adjust the extrusion volume of the squeeze roller, so that both ends of the weld to keep flush, opening angle of 7 degrees below the weld gap control in 1-3 mm. Weld control is too large, there may be poor welding, welds are not fused or cracked, weld control is too small, due to heat is too large, likely to cause weld burns, melting metal splash, tumor is too large, affecting welding quality The (Metal spatter reasons: squeeze the melting tube edge, the weld inside the steam pressure is greater than the surface pressure)


2. High-frequency induction coil position control
The position of the induction coil should be on the same center line as the steel pipe, and the distance between the front end of the induction ring and the center line of the pressing roller should be as close as possible to the steel pipe,will reduce the strength of the weld. The coupling of the induction coil is as thin as possible. When the lap is used, the width of the induction ring should be equal to the diameter of the pipe. The choice of single or double lap has a great influence on high frequency oscillation frequency and output efficiency.


3. Position control of the resistor (also known as magnetic bar)
The resistor is a group or a dedicated magnetic bar whose cross-sectional area accounts for 70% of the cross-section of the pipe. Its role is to strengthen the electromagnetic induction, concentrated weld edge of the eddy current heat. Sometimes the outside of the weld plus some magnetic rod, but also play a supporting role. The temperature of the magnetic bar has a great influence on the permeability, and the higher the temperature, the lower the permeability. The magnetic bar should be placed in the V-zone heating section, the front position in the center of the squeeze roller, the magnetic pole position and permeability directly affect the welding efficiency and weld quality.


4. Output heat control
High-frequency power input to the steel pipe weld part of the heat is called the input heat, the input heat is insufficient, the welding speed is too fast, the edge of the pipe body can not reach the welding temperature, the formation of non-welded or not penetrated cracks but the input heat is too large , The welding speed is too slow, prone to over-burning, so that the breakdown of the weld, resulting in metal splash, the formation of pores. By adjusting the high-frequency voltage or welding speed method to control the size of the input heat, so that the weld of the steel pipe does not appear without penetration and no welding phenomenon, to meet the welding quality requirements.


In short, the production process of high-frequency welded pipe is a special process, each link is more important, the implementation of strict control, the quality of welding and energy efficiency will have a significant role.