小型柴油机曲轴断裂,多数在曲柄与曲轴颈的连接处,有的在连杆轴颈油孔处或安装飞轮的锥形面键槽处。曲轴断裂时,柴油机发出强烈的敲击声,冒黑烟。完全断开时,柴油机熄火。断裂的一般原因有:曲轴材质缺陷;热处理不符合要求,硬度过高,韧性差;供油时间太早;长期超负荷工作;曲轴弯曲、扭曲;捣缸;主轴瓦间隙过大;飞车;主轴瓦座孔不同轴度超差;飞轮滚键等。此外,还有下列原因: 1.曲轴轴颈圆肩不符合要求因曲轴轴颈与曲柄之间过渡圆肩半径过小,或圆肩部分修整不好,在磨削中烧伤,使圆肩应力集中,导致曲轴断裂。 2.轴颈与轴瓦半干摩擦由于机油泵供油不足,或油路不畅通,使轴颈与轴瓦处于半干摩擦状态,或者烧瓦后,未认真检查有无裂纹,凑合使用,导致曲轴断裂。 3.飞轮偏摆或不平衡曲轴轴心线偏移,飞轮运转中偏摆,产生较大的惯性力,极易使曲轴疲劳折断。飞轮没有进行动平衡试验,或换用不同机型上的飞轮,转动时产生偏摆、振动,也是造成曲轴 Small diesel engine crankshaft rupture, most of the connection in the crank and crankshaft neck, some in the connecting rod journal hole or install the flywheel taper keyway Department. When the crankshaft breaks, the diesel engine makes a strong percussion sound and smokes black smoke. When completely disconnected, the diesel engine stalls. General reasons for the fracture are: crankshaft material defects; heat treatment does not meet the requirements, hardness is too high, poor toughness; fuel supply too early; long-term overload work; crankshaft bending, distorting cylinder; main bearing gap is too large; Bearing bush hole axis of different tolerances; flywheel rolling keys. In addition, there are the following reasons: 1. Crankshaft journal shoulder does not meet the requirements due to crankshaft journal and crank transition radius is too small, or the shoulder part of the dressing is not good, burns in the grinding, the round shoulder stress Concentrated, leading to crankshaft rupture. 2. Semi-dry friction shaft and bush As the oil pump insufficient oil, or oil flow is not smooth, the journal and bush in the semi-dry friction state, or after the tile is not carefully checked for cracks, improper use, resulting in crankshaft fracture. 3. Flywheel deviation or imbalance Crankshaft axis offset, flywheel deflection during operation, resulting in greater inertia, easily broken crankshaft fatigue. Flywheel is not dynamic balance test, or switch to flywheel on different models, resulting in rotation bias, vibration, but also caused the crankshaft