Crank of internal combustion engine after every process and hot surface treatment will produce fairly deformation , that is jumping overproof . so alignment without destroy for its tissue and property is important factor which ensure operation of crank safely 内燃机曲轴在各加工工序及表面热处理后会产生一定的变形即跳动超差,对其组织和性能无破坏的校直是保证曲轴安全运行的重要因素。