Abstract:Since the precision of finishing operations for crankshaft hole will directly affect the quality and life of the engine, an advanced and reasonable fixture system is very important for the machining accuracy. According to the precision requirement of cylinder crankshaft hole in the real applications, the process parameters and the positioning reference were determined in this paper, and the main structure of fixture system was designed and analyzed including the positioning mechanism, cutter relieving mechanism, clamping mechanism and boring mold. Finally, the dynamic characteristics of the boring bar were analyzed, and the effect of bearing stiffness on the dynamic characteristics of the boring bar was studied as well. By appropriately increasing the bearing preload, i.e., bearing stiffness, the stiffness of the boring bar system could be effectively increased. Based on the practical process inspection, the correctness of the design has been tested and verified.