Methods for manufacturing tubes filled with powdery and granular substances

摘要

A method for manufacturing tubes filled with powdery and/or granular substances comprising the steps of forming a metal strip into a tube, feeding powdery and/or granular substances into the tube being formed as a core, joining together the edges of the tube filled with the core of the powdery and/or granular substances by high-frequency welding, and reducing the diameter of the welded tube filled with the core of the powdery and/or granular substances. At least the top layer of the core in the tube is composed of powdery and/or granular substances having low enough magnetic susceptibility to remain unattracted to the magnetized tube edges that is determined based on the welding heat input.