Study On PCBN Tool Wear Based On Finite Element Simulation

PCBN tools are characterized with high hardness, stable chemical properties and excellent wear resistance, and compared with carbide tools, they have long service life, high processing efficiency, good quality of machined workpiece surface and high machining accuracy. Meanwhile PCBN tools are quite expensive, and as a new type of tools, the application of them among many enterprises is not in a very wide range and proficient way. So studying PCBN tools will promote their use and bring rapid development and economic benefits to manufacturing industry. During the process of metal cutting, tools, even those with high performance, are easy to get worn, which will reduce processing efficiency, increase production cost and bring the operators trouble or danger. Therefore, studying PCBN tool wear is important for reducing tools changing, guaranteeing processing quality and choosing reasonable cutting parameters and tool geometric parameters in practical process.On account of the above contents, this thesis has studied PCBN tool wear, combining finite element simulation analysis with relating experiments and regarding PCBN tools cutting high strength steel Cr12MoV as study object.First of all, in order to study the wear mechanism of rake and flank face of PCBN tools, experiments have been conducted on PCBN tools cutting Cr12MoV, using microscope with super depth of field to observe the tool wear of PCBN tools at different moments during cutting process and using scanning electron microscope to further detect and analyze elements of worn tools. In order to study the influence of cutting conditions over tool wear, single factor experiments have been conducted, separately altering the cutting parameters and tool geometry angles. Thus, the best cutting condition n the selectable range which can slow down the tool wear is obtained.Second, the secondary development of simulation software ABAQUS and the parametric concept have been introduced. The parametric user interface of ABAQUS two-dimensional cutting models has been created combining its secondary development script language Python and parametric theory, and the database of common materials has also been established, which sharply improve the pretreatment efficiency and make full preparations for later work of tool wear simulation.At last, two-dimensional and three-dimensional finite element cutting models of PCBN tools cutting Cr12MoV have been established based on the parametric modeling and the key technology of finite element such as constitutive models, friction models and chip separation criterion etc, simulation analyzing the influences of tool wear over cutting process, verifying through relevant experiments, summarizing the variation law of cutting force, cutting temperature, tools stress and chip shape according to different degrees of tool wear.