A Comparison Study On Wet & Dry Cutting Hardened Steel With PCBN Cutting Tools

According to the current literature and research in home and abroad, it is broadly believed that PCBN cutting tools will perform a better cutting performance in cutting hardened steel without cutting fluid. The use of cutting fluid will only accelerate the quick wear of PCBN cutting tools, increase the cost of manufacture and pollute environment. However, according to some investigation, the pure dry cutting technology of PCBN cutting tools usually meets many difficulties in some practical application, and some enterprises in home still use cutting liquid as a main method to decrease the cutting temperature in machining process. Facing the current problem and conflict between theory and application, a series of cutting experiments are carried out and the cutting forces, tool wear, surface integrity and the effect of cutting data on surface quality are investigated in this paper.This thesis includes five chapters. In the chapter of introduction, this thesis concisely outlines the history of development and application and tool wear mechanism of PCBN, summarizes the special characteristics of hard turning with PCBN cutting tools, and also reviews the study work done by precedent in the field of hard turning. In the chapter two, the thesis introduces the design of experiments and the selection of cutting data and materials including tool material, workpiece material, and machining tool. The experimental data are settled and calculated, some comparison curves are drawn, and furthermore some valuable pictures are taken by the advanced equipment such as SEM. In the third and fourth chapter, the effect of tool wear on cutting forces, the surface integrity, the wear mechanism and wear typed of PCBN cutting tools and the effects of cutting data on cutting forces and surface roughness and the saw-tooth gotten in experiment are thoroughly investigated when turning hardened GCr15 bearing steel with and without coolant based on the data and curves and pictures gotten in chapter two. In the end, several valuable and practical conclusions are made according to the chapter three and four.