BEAD CUTTING-OFF APPARATUS OF WELDED PIPE

PURPOSE:To prevent local wear of a tool and assure its durability life by connecting a joint mechanism between the cutting tool and a revolution-driving power source, when a driven number of revolutions of the cutting tool drops owing to a cutting resistance of welding beads. CONSTITUTION:A completely welded steel pipe 2c is removed of its internal surface beads Bi by a cutting tool 9 at the lower reach of a roll 8. That is to say, by a displacement of the steel pipe 2c, the cutting tool 9 is driven to revolution with removal of the beads Bi, however, here, the cutting tool 9 is pressed against the internal surface of the steel pipe 2c through a plane angle alpha and a solid angle theta and following a displacement of the bead Bi rotates around its own axis to remove the beads Bi by machine-cutting in the reversed direction. At this moment, when the cutting tool 9 is brought to a steady condition and the reversed revolution stops and a number of revolutions drops and that of a power shaft 32 exceeds that of a driven shaft 30, then a ratchet mechanism 37 is brought into engagement transmitting rotation of the shaft 32 to the shaft 30 and the cutting tool 9 is forced to rotate by an outside revolution-driving power source. Accordingly, the local wear of the cutting tool is eliminated and a longer durability life can be attained because of availability of revolutions in excess of a certain value.