| 摘要 |
<p>Apparatus for welding a longitudinal or spiral seam of a tube, using a medium frequency current, of the type in which the tube, formed from a metal strip by a set of rolls, can be advanced, the edges of the strip defining a V-shaped slit, in the zone of which the tube is surrounded by an induction coil, and encloses an impedance element which is provided with metal plates forming radial projections with their lateral surface arranged in each case, perpendicularly relative to the direction of the induced current circulating in this tube; these metal plates have a magnetic saturation of 20,000 Gauss and a permeability of 15,000-30,000 mu.</p> |
