Research On The Optimization Method Of Cutting Parameters For Turning Based On Virtual Machining

Manufacturing industry is an important pillar of the modern industrial economy, CNC machining technology in the manufacturing industry occupies an important position. In the actual processing of CNC, the processing parameters of the cutting speed, feed rate, cutting depth, etc. are often specified conservatively by the programmer in order to avoid excessive cutting force, vibration machine, which lead to damage machine and reduce machining precision, thus seriously limiting the efficiency in the use of numerical control equipment. The paper studies the method of CNC turning parameters optimization for the purpose of enhancing efficiency, reducing processing costs and accessing to high-quality products, the results have a wide range of economic and social benefits.Virtual machining simulation technology is a new stage of development of the current processing technology, it not only provide a realistic simulation of the processing environment, but also take into account the process of motion and dynamic characteristics in the geometric and physical simulation. This paper studies on the method of cutting parameters optimization based on virtual machining, the architecture is analyzed, which includes the function architecture and organizations architecture, and the workflow is identified.Because machining simulation is the basement to the cutting parameters optimization, the method of geometric modeling is proposed and the machining simulation process is realized by the use of the Boolean with the model of tool swept volume and work piece. It can effectively reduce the calculation time and improve the simulation speed by three-dimensional solid model converted to two-dimensional polygon model. At the same time in the machining process simulation, cutting parameters such as cutting depth and radius are acquired by the method of "polygon clipping", which are the basis of processing performance prediction and cutting parameters optimization system. In the simulation process, cutting force model is established with the empirical formula, the experimental results show that the predicted values are similar with the measured, which proves the simulation system has better predictive capability of processing performance and also indirectly verifies the correctness of acquired method of cutting parameters.Based on the conclusion of a single pass turning machining features, cutting parameter optimization strategy is determined on the basis of a discrete sub-processing path. Variables selected to optimize are spindle speed and feed rate. The function of constant cutting force is established a with efficiency, the rules of constraint of single pass turning are determined. The feasibility of genetic algorithm for optimization of single pass cutting parameters is carried out. The genetic algorithm is used. Through simulation, the optimization results are compared with the different largest number of iterations, crossover probability and mutation probability. The reliability of the optimization method is verified through repetitive simulation methods.Based on the conclusion of multi-pass turning machining features, the cutting parameters optimization method is researched. A mathematical model of minimum costs is the established. The instantaneous radius of the workpiece processing is considered in the mathematical modeling, which overcomes the limitations of over-simplification in the previous model. The integer nonlinear optimization method and GA algorithm are used to optimize cutting parameters in order to achieve the purpose of saving processing costs. Through examples, the results show that the algorithm can solve the problem of identification of multi-pass turning cycle times and allocation of the total allowance.With VC++6.0, a cutting parameter optimization system based on NC turning simulation is developed. Using the optimization system, spindle revolutions and feed rates in NC file for rough machining are optimized according to the multiple objectives: the constant machining forces and increasing machining efficiency. Using the optimal NC file, turning experiments are carried out and the experiment results show the validity and reliability of cutting parameters optimization system.