Patent ID: 9486845
Filing Date: 2016-11-08
CPC Classification: B21B,B21C,B21J

Claim Text:
1. An inner surface regulation tool, comprising: a mandrel; a plug which is detachably connected to the mandrel; and a connection member which connects the plug and the mandrel by a magnetic force, wherein one of the plug and the mandrel includes a column-shaped portion which extends in an axial direction of the one, and the other of the plug and the mandrel includes a joining hole which extends in an axial direction of the other and into which the column-shaped portion is inserted, and wherein the connection member is a permanent magnet which is attached to at least one of the column-shaped portion and the joining hole, and wherein the connection member is fitted to a groove which is formed on at least one of an outer circumferential surface of the column-shaped portion or an inner circumferential surface of the joining hole so that a gap is generated between a surface of the connection member and an opening surface of the groove, or the connection member is fitted to a mounting hole which is formed on at least one of a rear end surface of the column-shaped portion or a bottom surface of the joining hole so that a gap is generated between a surface of the connection member and an opening surface of the mounting hole.