Crack reason of crankshaft of explosion-proof oil-free air compressor

Crankshaft dehiscence mostly occurs at the corner transition of shaft neck and crankshaft.

Cause analysis: 1. The transition fillet of the crankshaft is too small. During heat treatment, the fillet is not processed in place, which causes stress convergence at the junction of the crankneck and the crankshaft; 2. 2, crankshaft rounded Angle processing is irregular, the radius is not equal, resulting in excessive non-uniform and cause stress convergence; 3, long-term overload of the equipment, so that the crankshaft stress deterioration, resulting in a decline in fatigue life; 4. The material itself has shortcomings, such as sand holes and shrinkage porosity in the casting, which reduces the bearing capacity of the crankshaft in practice; 5. Crack appeared in oil hole of crankshaft, oil infiltration made the crack gradually expand, and finally formed fracture.

Treatment methods: 1. Properly increase the crankshaft transition Angle, keep the heat treatment uniform, and eliminate the stress concentration; 2, to ensure the crankshaft round Angle processing quality, such as shape accuracy and roughness, improve the crankshaft fatigue strength; 3. It is forbidden to overload the equipment, and stop the machine for repair if the fault occurs, to prevent the equipment from working with illness; 4. Improve the casting technology of crankshaft to prevent sand holes, shrinkage porosity and other defects in the casting; 5, strictly control the crankshaft oil hole processing technology and quality, processing should be timely removal of burr, prevent crack.