Mandrel equipped with impedance device, electric-resistance welded pipe manufacturing device, and method for manufacturing electric-resistance welded pipe

Abstract

An object of the present invention is to properly control deterioration and damage of an impedance device for manufacturing an electric-resistance welded pipe due to induction heating, the resulting reduction in welding efficiency, prevention of mandrel breakage, and hindrance to production. The mandrel and impedance device of the present invention are a mandrel and impedance device for manufacturing an electric-resistance welded pipe, which are provided inside an open pipe in which end portions melted by an induced current are welded together. An impeder core made of a magnetic material and the mandrel for manufacturing the electric-resistance welded pipe, which is located inside the impeder core, serves as a support member of the impeder core, and is extended in a predetermined direction, are included. A recessed area is formed at a part of the impeder core within a predetermined size along an extending direction of the mandrel, and a size of the recessed area in a direction orthogonal to a running direction is 20 mm or more and ⅓ of a length of an outside dimension of the mandrel or less.

Dependencies are inferred from the claim text.