Surface Failure and Durability of Induction-Hardened Sintered Powder Metal Rollers and Gears with Various Hardened Depths

Abstract

In this report, the effect of hardened depth on failure modes and fatigue strengths of induction-hardened sintered powder metal rollers and spur gears was elucidated, including the effect of relative radius of curvature of the rollers. These experimental results were discussed by an amplitude of ratio of orthogonal shear stress to Vickers hardness. Failure mode of the rollers was spalling due to subsurface origin crack with slight micropits and that of the gears was pitting with spall near the pitch point independent of the hardened depth. The depths of spalling cracks agreed almost with the occurring depths of peak amplitude of the ratio of orthogonal shear stress to Vickers hardness. Surface durability of the test rollers increased as the surface hardness increased and the relative radius of curvature decreased. Surface durability of the test rollers and the test gears was hardly influenced by the hardened depth.

Influence of Shot Peening on Surface Durability of Case-Hardened Steel Gears (Influences of Shot Velocity and Shot Diameter)

“…In the case of the test rollers employed in the past paper (3) , the surface durabilities of the test rollers decreased due to the increase in the surface roughness, as the arc height became larger, that is, the shot peening became stronger. However, in the case of the test pinions employed in this study, the surface durability of test pinion GV60 was the largest, and those of the shot-peened pinions expect for test pinion GV60 were equal to that of non-peened pinion G. Generally, the surface durability becomes larger as the relative radius of curvature becomes smaller (11) . On the other hand, as shown in Fig.8, the surface durabilities of the test pinions, with a relative radius of curvature at the working pitch point of 8.39mm, were lower than those of the test rollers employed in the past paper (3) , with a relative radius of curvature of 15mm.…”

Influence of density and nickel content on fatigue strength of powder-forged gears - Comparison with ingot steel and sintered steel -

“…The effect of the nickel content on the (pmax)lim of the test specimen was not clear from Fig.9. Generally, the rolling contact fatigue strength increased with decreasing relative radius of curvature (Yoshida et al, 1994). The fatigue strengths of the test pinions, with a relative radius of curvature of 8.5 mm at the working pitch point, were larger than those of the test rollers with a relative radius of curvature of 15.0 mm (Fig.9).…”

Application of the wavelet transform to health monitoring and evaluation of dynamic characteristics in gear sets

“…The level j corresponds to the lower frequency, as the absolute value of j becomes larger. The relation between f j and g j is given by equation (13). Figure 7 shows the root mean square of the vibration acceleration plotted against n 2 .…”

“…The WT has some features different from those of the short-time fast Fourier transform or the Wigner-Ville distribution. Applications of the WT have been actively studied in a variety of fields in engineering [5][6][7][8][9][10][11][12][13].…”