Stress distribution in disk-type pipe-cutter wheels

The three-dimensional stress distribution in a disk-type pipe cutter, and the failure criteria of such a cutter wheel are investigated. A description is given of the measurement of the external forces acting on the cutter wheel. An epoxy model of the cutter wheel with embedded strain gages is described, and the measurement of the strains in the model is discussed. The cutting tests, where the external forces were measured, showed that the tangential component of the force on the cutter wheel increases drastically as the pipe size gets smaller. Failure of the cutter wheels started to occur while cutting a steel pipe 19 mm in outside diameter. The effects of cutting pipes of different hardness on cutting forces were also investigated. An epoxy model of the cutter wheel with strain gages embedded in it was built. This model cutter was rolled against a model pipe, which had a matching groove coated with silicone rubber to simulate the plastically deforming pipe material. From the gage readings taken, the stress distribution in the cutter wheel was calculated. The main cause of failure was determined as excessive plastic deformation near the tip of the cutter wheel. A low-cycle-fatigue failure occurred as a result of these large plastic strains. It was found that reducing the tangential traction would increase the life of the cutter wheels.