| 摘要 |
In a method for heating closely spaced end portions (3, 4) of two pipes (1, 2) to be joined by forge welding or the like two diametrically opposed contacts (6, 7; 8, 9) are attached to each end portion. High frequency alternating current is supplied through the contacts for resistance heating of the material in the end portions, the contacts (6, 7), for one of the pipes (1) being located in close proximity to and in the same axial plane as the contacts for the other pipe (2). In order to control the current flow in the immediate vicinity of the contacts and improve the current density in the areas midway between the contacts (6, 7; 8, 9), the contacts (6, 7) for one of the pipes (1) are arranged to form an angle ( alpha ) with the contacts (8, 9) for the other pipe (2). Further concentration of the current in the areas midway between the contacts may be obtained by placing ferrite bars (13) inside and/or outside the pipes (1, 2) in the joint area (3, 4).
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