Study On Remanufacturing Process For Engine Crankshaft By Laser Cladding

The journal of engine crankshaft will be wear and cracks in the long run the process. If the injury was repaired, not only the cost is saved, but also the resource utilization is improved. In order to achieve the laser cladding remanufacturing on engine crankshaft, by taking crankshaft as research object, the effects of laser cladding process parameters on property of layers have been studied; The trajectory of laser beam was deduced according to the trajectory of crankshaft rod journal and experiments on laser cladding have been studied.(1) The macroscopic morphology of cladding layers were observed by laser cladding with different kinds of powder, and the linear expansion coefficient of powder and substrate was tested to obtain suitable powder for the substrate.(2) The single-layer and overlapping-layer Iron-based coating on45steel has been obtained by laser cladding. The effects of laser cladding process parameters on property of layers have been studied. The morphology and microstructure of layers were observed by scanning electron microscope(SEM) and energy dispersive spectroscopy(EDS). The hardness of layers was tested by Vickers hardness tester. The changes in microstructure and hardness of layers were analyzed with varying laser power and laser scanning speed. It was observed that as the scanning speed increases, the microstructure of cladding layer is finer, and the hardness of the cladding layer firstly increases, then decreased slightly. As the laser power increases, the microstructure of cladding layer is coarser and the hardness of the cladding layer decreased slightly. The multi-layer and overlapping-layer Iron-based coating on42CrMoA steel has been obtained by laser cladding. The morphology and microstructure of layers were observed and the properties were tested.(3) The crankshaft is fixed at the level of the machine without eccentric device. the trajectory of laser beam and crankshaft rod journal are deduced through the motion analysis, and the requirements to obtain the continuous and uniform cladding are proposed, under the condition, the relative speed of laser beam and rotating journal are deduced.(4) The depth and microstructure of nitride case on the surface of the crankshaft were measured and observed. The effects of nitride case on microstructure of layers have been analyzed by laser cladding experiments with and without nitride case. Based on the motion control and calculation of the relative speed during laser cladding, the experiment on crankshaft rod journal has been done and the feasibility of the model is verified.