How do I repair my crankshaft after it has worn?
Generally speaking, journal diameters of less than 80 mm with roundness and cylindricity errors exceeding 0.025 mm; or journal diameters of more than 80 mm. Crankshafts with roundness and cylindricity errors exceeding 0.0400 should be ground to the specified size, or ground to the specified size or repaired size after vibratory overlay welding, chrome plating or iron plating.
1. Crankshaft grinding
The grinding of crankshaft journals is carried out on the basis of crankshaft alignment. In addition to the dimensional accuracy and surface roughness of the journals meeting the technical requirements, the grinding of the crankshaft must also meet the requirements for form tolerances. When grinding the crankshaft, the coaxiality of the main journal and connecting rod journal axis and the parallelism of the two shafts are ensured and the crank radius error is limited. The accuracy of the angle between the positions of the connecting rod journals is guaranteed. The grinding of the crankshaft is usually carried out on a special crankshaft grinding machine.
2. Grinding of connecting rod journals
Due to the uneven wear of the connecting rod journals, there are two grinding methods: eccentric grinding and concentric grinding.
The reasonable choice of materials and the requirements of the prescribed heat treatment for drop-forged parts are important to increase the strength and service life of shaft components and, at the same time, have a large impact on the processing of shafts. Shaft components are generally made of 45 steel, with different heat treatment specifications (e.g. normalised, tempered, quenched, etc.) to obtain strength, toughness and resistance to wear, depending on the working conditions.