Analysis of gear material quality inspection results and distortion cause
① Gear inspection result. According to the conventional process, the end surface is seriously warped and irregular. After quenching, the inner edge of the end surface is 0.4mm and the outer edge is about 0.25mm. After pressure quenching, it is placed for about 1h, the warping amount is still increasing, and the distortion continues to increase after cleaning and tempering.
② aberration analysis. Retest sampling, its chemical composition and quenability qualified. Check the original tooth blank (hot front white parts) metallofacy, hardness qualified. Quenching oil to replace the Fulton rapid quenching oil, still deformed super poor. After examining the macro low fold defects of the raw material round steel, it is found that it is different from the steel materials of other manufacturers, the abnormal material segregation frame and dendrite area are asymmetric, too close to the surface of round steel, the loose area is large, resulting in uneven section density (the maximum difference is about 3 times), and the content deviation between the surface and the central area is large.
In addition to the narrow quenching belt, the gear improvement measures should also control the uniformity of the components in the steel. C, Ni and Mo should be controlled within ± 0.01%, and Mn, Cr and Si should be controlled within ± 0.02%.
