高周波焼入れ粉末焼結ローラの面圧強さに関する研究 : 圧粉密度および相対曲率半径の影響

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The purpose of this study is to elucidate influences of green density and relative radius of curvature on surface durability of induction-hardened sintered powder metal rollers. Three kinds of rollers, which have green densities of 6.5, 6.9 and 7.3 g/cm^3 respectively, were fatigue-tested using two cylinder testing machines under a sliding-rolling contact condition. The surface durability of the roller increased as the green density of the roller increased. The pore size and the pore cluster factor presented by fractal dimension decreased as the green density increased. The pore size and the pore cluster factor influenced the surface durability of the roller. The surface durability of the roller increased as the relative radius of curvature increased. The failure mode of all rollers was spalling due to subsurface cracks propagating parallel to the roller surface. The minimum depth of the spalling crack agreed almost with the depth of the peak amplitude of the ratio of orthogonal shear stress to Vicker's hardness. To evaluate the surface durability of the sintered powder metal rollers using the amplitude of the ratio of shear stress to hardness, some factors which modify the shear stress may have to found out considering the pore size and the pore cluster.
1996-04-25