直缝高频焊管焊接不用磁棒可以吗

box

直缝高频焊管焊接不用磁棒可以吗

Is it possible to induction weld without using impeders?

      Impeders are less necessary when welding non magnetic materials. This because the degree of high
frequency “skin effect” varies among different materials and is most pronounced in carbon steels. Below
Curie temperature, 90% of the current flow in carbon steel is confined to within 0.005" of the surface. The
skin depth is greater for non magnetic materials, typically 0.040" in the case of aluminium. Since current
cannot flow in two opposite directions at the same time, materials that are thinner than twice the skin
depth have less need for impeders, and light walled aluminium tubing is often welded without them.
There is always some benefit to be gained from using an impeder. In addition to opposing current flow
around the inside surface of the tube, an impeder increases the transfer of energy from the coil to the
strip by “focusing” the energy in the area where it is needed. The coil has to produce a much stronger
(and larger) magnetic field if an impeder is not used, and this causes wasteful and destructive heating of
the weld rolls and other steel parts in the vicinity.

      There are a few instances where weld quality may be improved by not using an impeder, and the higher
power requirements may be a worthwhile trade-off. Under normal circumstances the tube edges are
heated to a forging temperature that is well below the melting point of the material, but because the high
frequency skin effect concentrates so much energy at the strip edge, the surface will sometimes melt,
and this molten material is forced out of the weld area as a result of the pressure applied by the squeeze
rolls, causing a large, rough weld bead to occur. This overheating may also cause oxidation and if oxides
are not forced out into the bead, weld defects will occur. The heating can be made more gradual by
either moving the coil, the impeder or both, or in some cases eliminating the impeder altogether. If
impeders are not used, the R.F. voltage across the coil will be much higher, and care must be taken to
avoid flashovers.

      For tube diameters in the 3/4" to 2 1/2" range, induction welding without impeders will normally require
50% to 100% more power.

zhangbin0427

感应焊可以不用磁棒的

yyq123

感应焊必须用磁棒，用磁棒的目的就是提高有用电流，减小无用电流来提高焊接质量，不用磁棒怎么焊。

box

看文章，里面都交代清楚了，仔细看看