Study On Strengthen Theory And Key Technologies Of Crankshaft Fillet Rolling

Automotive engine crankshaft is the part of the most important and bear the largest load.The main destruction form of the crankshaft is bending and fatigue damage, and the origin of fatigue cracks on the stress concentration at the transition from the crank to the crankshaft journal fillet. Fillet rolling can significantly improve the fatigue strength of ductile iron crankshaft, because of the density of ductile iron is less than that of cast steel, a large number of metallic materials could been saved if ductile iron crankshaft is taken the place of cast steel crankshaft. Rolling process is been need to product the ductile iron crankshaft, while the crankshaft rolling equipment and market have been dominated by foreign companies,to study the key technologies on crankshaft fillet rolling and develope the related equipment have great significance in practical applications.The crankshaft rolling, runout testing and straightening processes were introduced in this paper. By FEM numerical simulation calculation, in different circumstances such as controlling load in different ways, rolling laps, rolling pressure, cutting groove, the crankshaft rolling and strengthening effect about stress and strain distribution were surveyed, a theoretical reference for the rolling process was provided.In Windows circumstance, VC programming for closed-loop control of pressure was programed. A neural network model of controlled object was established too. The internal model controller was constructed. The fluctuation of dynamic clamp pressure was suppressed effectively. A test method of measurement of the residual stress was discussed by detecting the depth of the depressed and a method that constant rolling machine would been transformed into inotropic rolling machine was proposed.A mathematical model of measurement deviation was established, simultaneously, the pendulum was developed based on LVDT differential test hardware system. When the axis of the measured workpiece does not coincide with that of rotary axis,the methods of the data vector synthesis should been used to eliminate bias.The differential phase of pendulum was amended by the method of least squares and the approach of vector model to transform data of runout was proposed. Finally, the top test results under the benchmark was transformed into the theory test results underâ…¤-shaped iron, the actual deformation of the crankshaft basically is as same as the results of manual testing.By using the method of least squares support vector machine combining multiple classifiers, the crankshaft straightening position classifier was constructed. By the use of BP neural network, mathematical model of decision-making straightening expert was established, a variety of decision-making parameters were synthesized and output with the method of data treatment.A pulse and direction motors system interface circuits was designed, the small-scale numerical control systems and PLC systems were developed with independent intellectual property rights. IPC had developed into the numerical control system communication protocol, the communication between IPC and PLC was carried out with the VC program. By the use of the memory cell, a working state synchronization control was achieved.The microstructure of rolling crankshaft was investigated,the micro-mechanism of the crankshaft strengthen was identified. Rolling layer of grain was taken place local plastic deformation, so that the matrix densification and the stress concentration was improved. At the same time rolling layer of intragranular dislocation density was increased leading to the crankshaft strength increased. The stress test of rolling parts had been tested, the results shown that both the axial and tangential residual compressive stress was generated, the more close to the surface the larger value of residual compressive stress was generated.To Summary, By the using of the finite element simulation, theoretical studies, samples analyseing and experimental testing,the key technologies about crankshaft fillet enhanced tested and straightened process was studied. A high degree of automation Crankshaft Fillet Rolling Machine was successfully developed, occupying part of the domestic blank market.