The Research Of Processing Technology For Engine’ High Precise Screw Holes

The threaded hole processing on the crankshaft is the key process of machining. But the traditional machining method s have some problems, such as low precision, the tools are easily damaged. The screw holes that are formed by the traditional ways also have the problems of sintered and looseness. There are fatal hidden troubles in the screw holes. And in this way the holes need manual adjustment, it must reduce efficiency. By comparing kinds of machining methods, selected thread milling as the final plan. It has the advantage of high precision, high efficiency, low cost and easy to be batch produced. The thread milling has not been widely used because need 3-axis milling machine tool at least. With the CNC machines are used widely, more and more enterprise would use the thread milling.In the project, we design the process flow of thread milling, and select the appropriate tools combining the knowledge of cutter and the NC program were made based on the machining principle. Using orthogonal experiment method can determine the key processing parameters of thread milling for improving the machining quality and efficiency. The experiment took cutting linear speed, feed per tooth and back engagement as the influencing factors. Every factor would have 4 design levels. The components would be processed on a three axes linkage machine tool, and would analyze experiment data. The result shows that the degrees of impact of the factors in thread milling from high to low are: feed per tooth, cutting linear speed, back engagement. Then the feed per tooth was optimized by single factor test to get the optional combination of parameters. The predicted model was calculated on the base of experiments.Now the blot holes and the bolts have the disadvantage of insufficient strength. In this paper, we made a force analysis about the moving process of crankshaft counterbalance and bolts, and used UG to create the 3D model of the bolt and the blot hole. We also used ANSYS to do finite element analysis and simulation about the bolts’ force. And we proposed the improvement measures of the existing thread design based on the regularity of stress distribution.