发动机缸体曲轴孔精加工专用夹具设计与研究

曲轴孔精加工工序的精度将直接影响发动机的寿命与品质，而先进合理的夹具系统是加工精度的重要保障。针对某企业对缸体曲轴孔精加工精度要求，确定了工艺参数及定位基准，在此基础上，对夹具系统的定位机构、让刀机构、夹紧机构及镗模等主要结构进行了设计与分析。最后，分析了镗杆的动态特性，并研究了轴承刚度对镗杆动态特性的影响，适当提高轴承预紧力即轴承刚度，能有效提高镗杆系统的刚度。经实际加工检验，验证了设计的正确性。

Design and study on special fixture for finishing cylinder crankshaft hole

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.