The provided method and material-removing tool serve for producing an exact-fit cylindrical bore with a high degree of surface quality and a length that may be a multiple of the diameter from an existing bore with a finishing allowance. In order to reduce the time taken for the finishing by means of a reamer to be performed, it is proposed to use a tool in the form of an impact die, which is formed at the front end with a circular or substantially circular cutting edge, the diameter of which corresponds to the nominal diameter of the bore to be produced, and which tapers from directly behind the cutting edge or behind a front region of a certain length.

An object is to prolong the life of a ring tool, and improve the productivity of a welded pipe. A ring tool unit is held in a downstream-side end portion of a mandrel to be inserted into a welded pipe currently being manufactured from the upstream side of a welding position, and is used as a cutting tool for continuously cutting a bead produced on the inner surface of the welded pipe, wherein the ring tool unit is formed by fitting a ring tool having a ring-like blade in a sleeve having a circular hole for holding the outer circumference of the ring tool.

An object is to prolong the life of a ring tool, and improve the productivity of a welded pipe. A ring tool unit is held in a downstream-side end portion of a mandrel to be inserted into a welded pipe currently being manufactured from the upstream side of a welding position, and is used as a cutting tool for continuously cutting a bead produced on the inner surface of the welded pipe, wherein the ring tool unit is formed by fitting a ring tool having a ring-like blade in a sleeve having a circular hole for holding the outer circumference of the ring tool.