Appreciable Increase of Load Carrying Capacity in Rolling and Sliding Contact : For 180 HB Carbon Steel

抄録

Pitting fatigue limits obtained from many past investigations were in the range p_max = (0.2=0.35) HB and they were less than the lowest shakedown limit (p_max = 0.4 HB; past theoretical pitting limit) when test rollers made of steel were rotated under rolling and sliding conditions. In the case of pure rolling, it was recently demonstrated by the present authors that pitting fatigue limits became greater ( e.g., p_max = 0.7 HB) when a testing machine made by the authors was used with precise test specimens. However, in the case of combined rolling and sliding contact, an attempt to increase the pitting limits of rollers was unsuccessful, as expected by many investigators. After unfruitful experiments for about one year, the authors succeeded in appreciably increasing pitting limits using another new testing machine with an improved performance. Not even a single pit occurred at specific slidings 1.5 to 29% at a Hertzian stress of 123 kg/mm² (p_max = 0.68 HB) when 180 HB steel rollers ground to a surface roughness of 1 μm R_max were used in equal hardness combinations. Moreover, no pitting occurred on a 180 HB roller up to 10⁷ rotations at a Hertzian stress of 137 kg/mm² (p_max =0.76 HB) when the soft roller was combined with a superfinished hard (420 HB) roller and rotated at a specific sliding of about 20%.