Internal pipe cutter

Abstract

A device for cutting pipe internally includes an annular cutter head having a plurality of circumferentially spaced openings therethrough, a stepped drive shaft extending from the cutter head and having a longitudinal bore therethrough and an adapter at the distal end of the drive shaft for connection to a rotary drive member. A frustoconical mandrel has a threaded rod extending from one end thereof through the shaft bore to the distal end of the shaft where it threadably engages a nut held stationary with respect to the drive shaft. The mandrel has a plurality of inverted T-shaped slots extending along the frustoconical side thereof, each slot receiving the T-shaped projection on a cutter body. Each cutter body has a rotatable cutter wheel mounted thereon, the wheel being adapted to project through a corresponding opening in the cutter head. Rotation of the drive shaft by the rotary drive member will cause rotation of the mandrel and the threaded rod. The relative movement between the threaded rod and the nut causes the rod to move through the nut so as to draw the mandrel into the cutter head. Due to the sloping nature of the mandrel wall and the interengagement between the T-shaped slots and projections the cutter bodies and the cutter wheels will be moved progressively radially outwards of the cutter head during rotation of the drive shaft so that the cutter wheels can cut into the internal wall of the pipe at a controlled progressive rate.