Multi-Constrained Analysis In Optimization Of Metal Cutting And Its Application

The trends of cutting technology are high-efficiency, precision, intelligent and environmental-protection; therefore rigorous requirement has been brought for the cutting tools and workpiece materials. Cutting tools must have the characteristic of high-efficiency, high-precision, well-reliability and specialization; materials with good machinability and less polluted of environment should be guaranteed at the same time. With the development of the manufacturing industry, high performance workpiece materials and complex parts have been widely used, which are becoming a huge challenge to the optimization of cutting process. In particular, the high performance cutting process leads inevitably to the contradiction between the cutting tools and workpieces in some extent, such as: the decrease of tool life, loss of precision and deformation of thin part due to the poor machinability of the workpiece material. Thus optimum cutting process is becoming a critical issue. Goals and constrains of the cutting process change with the cutting conditions, so multi-goals and multi-constrains are the basic characteristic of the cutting process. In this dissertation, gray-system theory is introduced to establish multi-constrained model for cutting optimization. Innovative results have been achieved with the help of this theory, especially in exploitation and utilization of high performance tools, development of high performance materials, initiative-control of burr generation in high speed machining and limitation of deformation in machining thin parts. The main works of this dissertation include:1. The concept of multi-constrained analysis in the cutting process is presented for the first time in the dissertation. The dissertation applies a method to solve an important problem which is how to judge the influence of constraines during cutting processs. The mathematic models of the multi-constrained analysis are built by grey theory, and the multi-constrained system in the cutting process is analyzed in the dissertation.2. The multi-constrained analysis, the simulation of the cutting process and the method of standard experiments are combined in the dissertation for the first time. Focusing on the practical machining process, by means of analysis of different constrains, the feasibility of tool design and technology in the practical machining process are studied. The feasible spaces of the process parameters and tool parameters are constructed and the optimized models are presented, that provided the theoretical basis for the high-performance manufacturing of intricate parts.3. On the basis of the multi-constrained analysis of tool design combined with methods of simulations and standard experiments, the optimum methods are provided for structure, coating and cutting parameters of cutting tools. The research results are applied for development of special milling tools for hardened steel and drills for stainless steel. These products were introduced to the market.4. The multi-constrained analysis of the machinability of nonleaded low carbon sulphur free-cutting steel is studied. The influence of elements to machinability of nonleaded low carbon sulphur free-cutting steel is analysed. The feasible spaces of optimum machinability were constructed, which provided the theoretical basis for the development of new nonleaded low carbon sulphur free-cutting steel. On the basisi of the research results, new free-cutting steels were developed by a large steel company.5. By means of the method of combining the multi-constrained analysis, simulation and standard experiments, the optimum methods for avoiding bur and deformation during milling of aluminum alloy are presented respectively. The optimized instructions are applied successfully in the cutting process of aluminum radar framework of battleplane and rib parts of even tail.