An effective optimization algorithm for multipass turning of flexible workpieces

Excessive deformations and chatter vibrations are two main obstacles frequently encountered in turning of long slender workpieces. So far, there is seldom reported research using optimization techniques to cope with those difficulties. This paper introduces a new method for optimizing the machining parameters and the sequence of cutting passes in turning of a slender rod to control the deformation and chatter. The mathematical model is formulated, in which the deformation and chatter constraints are intensively derived. The optimization problem is solved in two phases. The first phase is to determine the minimum production time for an individual cutting pass for the predefined depths of cut. A hybrid solver combining a genetic algorithm and sequential quadratic programming technique is adopted to accomplish this step. In the second phase, a dynamic programming technique is employed to achieve the optimal sequential subdivision of the total depth of cut. A simulation experiment illustrates the methodology in detail. The inclusion relation of the solutions and the effect of the defined series for depth of cut are discussed. This proposed method has been proved effective and of generality in comparison with the previous works.