Failure Analysis of Gear Box Tooth of High Speed Digital Hobbing Machine Tool

Aiming at the problem of severe fatigue and wear of the involute gears of the gearboxes of several-roll machine tools, the two-dimensional image measuring instrument, gear testing instrument, surface roughness tester and hardness tester were used to analyze the microscopic morphology, contour and tooth surface hardness of the gear and the roughness. The results show that there is obvious scratch damage on the surface of the driven wheel, the surface roughness Ra reaches 1.340μm, the total deviation Fα of the tooth profile after fatigue wear of the driven gear is 0.89 μm, and the wear of the driving wheel is 2.5 times than that of the driving wheel. The surface has obvious micro-cutting morphology, the surface roughness R_a is 0.6 μm, and the microhardness is significantly larger than the tooth surface hardness of the driven wheel. The main causes of severe fatigue and wear of the gear are: the surface roughness and hardness parameters of the main gear and the driven gear do not match. The root of the gear has a deep cutting groove, local stress concentration appears at the tooth root, which can make the driving wheel wear deteriorate.