The Study And Application Of Manufacturing Crankshaft For Diesel Engine With 6 Cylinder

The crankshaft is one of the most important accessories for diesel engine. The semi-finished product, the construction, the material, the size and the weight of the crankshaft depend on the requirements of the type and the function of the diesel engine, which determines the ways of processing. Additionally, different processing increases the difference of the process flow, the level of the process optimization and the automation. Nevertheless, the elementary process flow of it is the same.This thesis discusses the manufacturing process of the crankshaft of the 6-cylinder diesel engine, introduces the design of the 160 series process dimension chain, and analyses the problem of exceeding the axial tolerance limit and proposes the solution to it. Meanwhile, the author introduces a novel way to make the distribution of the complex process dimension chains easily, namely---the Map Analysis, whose steps are as the following: ⑴ Select the appropriate main dimension (standard criterion); ⑵ Set up the units of main process dimension chain; ⑶ Design the related dimension from the middle to the both borders, from the density to the dispersion. This method fits all kinds of the distribution of the process dimension chain in the classical mechanical process, especially for the multiple process dimension chain design, so it has certain application value. Before improvement and application, the 160 series crankshaft's related process capability index (Cpk) is below 0.6, which falls into the range of poor process capability, and frequently exceeds the tolerance limit. Fortunately, following the application of the Map Analysis, the related process capability index (Cpk) always stabilizes between 1.1 and 1.33 and meet the level of the process capability. So the problem of the 160 series crankshaft's axial tolerance limit has been resolved and achieved remarkable economic benefits.This thesis also discusses the design and the application of the 170 series crankshaft process. Since the crankshaft is the softness parts and it has poor process stiffness, so this special method must be adopted to improve its stiffness, and at the same time the heat treatment process must be arranged properly in order to decrease the influence of the thermal deformation to the process precision.