1989 Volume 75 Issue 8 Pages 1370-1377
Breaking accidents which started at the center bore face of the journal of large sized backup rolls were experienced. To settle these problems, the working stresses inflicted on the center bore face of the backup roll was analysed by the three-dimensional photoelastic method. The fatigue strength of the test pieces taken from the core part of the journal and the residual stresses were also investigated. The main results obtained are as follows:
1) Though the repeated tensile stresses were inflicted on the center bore face of the journal, they were not so large. It is thought that the main cause of the fracture in question was the residual tensile stresses there.
2) The fatigue strength in the core part of the journal was equivalent or less than the fatigue strength of the sharp notched test pieces.
3) It was concluded that the breaking accidents from the center bore face could be prevented by giving the residual compressive stresses on the bore face.
