论文部分内容阅读
加工表面光洁度低,是发动机曲轴轴颈迅速磨损的原因之一。加工到7级(Pa—1.25微米)的曲轴轴颈的耐磨性比加工到9级(Pa—0.32微米)的要低15～18％。通常,许多修理厂将曲轴轴颈一次磨削至修理尺寸,所得的表面光洁度一般不超过7级。7级表面有明显的刀痕——明显的大量深的显微裂纹。在使用过程中这层表面很快磨平,与更光洁的表面相比较,其抗蚀性和疲劳强度较低。9级光洁度表面上没有尖锐的尖锋和沟谷,表面较为光滑平整。如经二次磨削至修理尺寸(粗磨至7级,精磨至9级),其精
Low machined surface finish is one reason why the crankshaft journal of the engine is rapidly worn out. Crankshaft spindles machined to Grade 7 (Pa-1.25 microns) have 15 to 18% lower wear resistance than those machined to Class 9 (Pa-0.32 microns). In general, many repair shops grind their crankshaft journals to a repair size once, resulting in a surface finish of no more than seven. Grade 7 surface has obvious marks - a significant number of deep deep micro-cracks. The surface is smoothed out quickly during use, with less corrosion and fatigue than a smoother surface. 9-level finish There is no sharp spikes and valleys on the surface, the surface is relatively smooth and smooth. If the secondary grinding to repair size (coarse grinding to 7, refined to 9), the fine