Research On The High-performance Material Cutting Tools And Their Cutting Performance

Ti(C,N)-based cermets are widely used in cutting tools because of its excellent abrasive resistance and good chemical stability under the condition of high temperature. However, the Ti(C,N)-based cermets are hard and brittle materials and how to increase the strength and toughness of the material to improve the Ti(C,N)-based cermets tool life is a difficult problem for the researchers. Polycrystalline cubic boron nitride (PCBN) cutting tool has obvious advantages in machining high hardness materials because of its high hardness and good chemical stability. It is important to apply the PCBN tools in machining iron-based powder metallurgy parts to attain the value-maximum. The experimental researches aiming at these problems are as follows:(1) Researches on the Ti(C,N)-based ceramic tools:The two groups of Ti(C,N)-based cermets with different original TiC particle size were prepared via the method of powder metallurgy and vacuum sintering process. The mechanism of the TiC powder particle size in increasing Ti(C,N)-based cermets strength and toughness was studied. It is concluded that Ti(C,N)-based cermets prepared with raw TiC nano-powder have a smaller grain size and better material comprehensive properties. The refinement of the ceramic grains increases the bending strength and hardness of the material. However, the binding phase in the ceramic matrix prepared with raw TiC micro-powder has higher mean free path increasing the toughness of the material.(2)The two groups of Ti(C,N)-based cermets mechanical properties were tested by actual cutting experiments. The results showed that:a best tool life can be obtained at the clearance angle of 5° when cutting normalized medium carbon steel 45) with Ti(C,N)-based cermets tools. The tool life of the nano Ti(C,N)-based cermets tool is better than that of micro Ti(C,N)-based cermets tool. The wear patterns an wear mechanisms of the two groups Ti(C,N)-based cermets tools were further studied and it was found that they have almost the same wear mechanisms. The abrasive wear, adhesive wear, diffusion wear and oxidation wear were occurred on the flank surface. The diffusion wear and oxidation wear are the main wear patterns in the experiment.(3) The modeling and numerical simulation of the cutting process were conducted with the finite element software ABAQUS. The influence of the rake angle and cutting speed on the complicated cutting process were analyzed. The two important parameters of the simulation, cutting force and shear angle, are verified by the experiment. The simulation can reveal the cutting state intuitively and provide experimental and theoretical guidance for the producing of the practical high-performance material tools. It also reduces the development cost of the new cutting tools and improves efficiency.(4) The iron-based powder metallurgy valve seats were cut with PCBN tools in the experiment. The results show that the density, hardness, hard particle hardness and crushing strength of V581 iron-based powder metallurgy material are better than those of ZN-1. The influence of cutting depth on cutting force is the largest, feed rate is less and cutting speed is the least. The radial force is the largest one among the three-dimensional component forces and is almost twice axial force. The main wear patterns of cutting powder metallurgy parts with PCBN tools are crater wear on the rake face, flank wear and micro-tipping. The main breakage forms of PCBN tools are the fracture of tool nose and chipping of the rake face. During the experiment, the main wear pattern of the rake face is chipping and serious chemical wear is occurred on the flank face. The mechanical wear always exists in the tool wear because of the hard particles in the powder metallurgy material.