Papers by Author: Osama Yaguchi

Abstract: The cam-shaft for the internal-combustion engine needs to be chilled at the foundry stage to rise the cam hardness, but unexpected chilled structures could occur on the sensor plate surface. If chilled structures exist on the sensor plate, a grinding tool may break when grinding sensor plate, or the specified shape may be unable to be produced due to resistance arising from the hyper-hardness of the chilled structures. For this reason, developing an inspection technique and a device for detecting unnecessary chilled structures before grinding the cam-shaft and for determining the rejection and removal of cam-shafts with chilled structures detected was necessary.

Abstract: In this study, the authors investigated the application of the area detector type method for the purpose of evaluating residual stress in tools having a V-groove. The specimen used was a shot-peened forming rack. This alternative method uses a diffraction ring and single incidence X-ray to clarify precisely and effectively complex stresses and stresses in narrow parts of the tools such as the teeth on the surface of the rack. In addition, the authors evaluated stress gradients generated after shot peening using synchrotron radiation (SR).

Abstract: In this study, the authors investigated the application of the area detector for the purpose of evaluating residual stress in rails by means of diffraction technique. A rail used in the Hokuriku-Line of West Japan Railway Company (JR-West) was used as a specimen for this study. The rail was removed due to initiation of cracks caused by rolling contact fatigue. The present method refers to neutron stress measurement with a two-dimensional detector and corresponding data analysis.

Abstract: In order to study on the effects of grinding of rail head on rolling contact fatigue of rails, residual stress measurements were conducted for rails processed under different grinding conditions. In this study, residual stresses in rails used for a service line were measured with the method of X-ray stress measurement. The triaxial stress analysis was conducted using a new method for an area detector type X-ray stress analysis proposed by the authors. Four grinding conditions were used to rail specimens. The distributions of residual stresses in the surface layer of the rail head were obtained. It was found that the tensile residual stresses were generated at the field-side of the ground rai1, and that the triaxial stress state was formed in the surface of the rail head widely.