Studies On Chamfer Effect Of PCBN Cutting Tool And Its Cutting Performance For Machining Nodular Cast Iron

The PCBN cutting tool, with many advantages such as good wear resistance, thermal and chemical stability, low friction factor and so on, has incomparable superiority when hard machining ferreous materials, instead of grinding, is becoming a new kind of finish machining way. However own to high friability, the PCBN tool is easy to be broken in cutting process, which reduce machining process reliability greatly, and result in large economic loss for its high cost. Therefore, the cutting edge of PCBN tool must be disposed to enhance breakage resistance before machining, and the most common and effective method is to grind chamfer on cutting edge. In this way, the efficiency and reliability can be improved greatly. However the chamfer parameters often were selected just refering to the experiences of cement carbide tool, having not the special instructional theory, hence, it is necessary to carry on in-depth investigation in the effect of PCBN tool.Both in home and abroad there was abundant research on cutting hardened steel with PCBN tool, and many valuable experimental results and conclusions were obtained , but the research on PCBN tool cutting cast iron was rather limited. Except for research and discuss on turning and milling gray cast iron under high cutting speed, only few studies about machining nodular cast iron and vermicular cast iron with PCBN tool were carried out, while the two materials are widely used in manufacturing, specially automobile, aviation and machine tool. Therefore how to cutting these hard-to-machine materials economically and effectively is becoming an urgent-to-solve problem.There are four chapters in this thesis. In the chapter of introduction, the characteristics and application of PCBN tool were summarized and reviewed, and hard cutting technology and the situation of PCBN tool applied to machining cast iron were concisely introduced. In the chapter two, the effect of chamfer parameter of PCBN tool on cutting force, tool life, surface roughness and chip form was systemically investigated, meanwhile the variety relations between cutting parameters and cutting forces were verified when the PCBN tool turning hardened steel. Through disposed and analysed the experimental data, it was concluded that the best machining effect can be gotten at the chamfer parameter of γ ₀₁=-15° ,b_γ1= 0.2mm when the PCBN tool finish machining hardened bearing steel. In the third chapter of the thesis, the performances of the two high content CBN tool (BN500 and BN700) in machining nodular cast iron were compared and analysed, and the results about the wear...