Synergetic approach to improve the efficiency of machining process control on metal-cutting machines

Abstract

Introduction. The efficiency of processing on metal-cutting machines is evaluated by the reduced cost of producing a batch of parts while ensuring the required quality. In modern production, parts are usually made on CNC machines. Today the CNC program and the trajectories of the machine tool actuators match each other with high accuracy, which, however, does not yet guarantee quality and efficiency of production. The definition of the CNC program is based on the knowledge base of rational modes, tools, coolant and etc. during processing. This base reflects some averaging over the set of machines, tools and processing conditions, and does not take into account changes in the properties of the dynamic system in the process of cutting. Subject. The paper deals with the synergistic matching of external control (CNC programs) and cutting dynamics (internal control). The internal control factors can be set a priori, as well as determined as a result of the influence of irreversible energy transformations in the cutting zone. The purpose of the work is to determine the law of controlling the trajectories of the machine's executive elements in such a way that, with changing properties of the dynamic cutting system, the required surface quality of the part and minimizing the intensity of tool wear are ensured during the processing of the part. Method and methodology. Mathematical simulation of the controlled dynamic system, which properties change due to the a priori set laws of variation of subsystem parameters, as well as changes in the cutting properties conditioned by the power of irreversible energy transformation is presented. Consideration of the power of irreversible energy transformations is necessary for predicting back-edge wear, changes in dynamic coupling parameters, and evolutionary restructuring of cutting dynamics. Results and Discussion. The regularity of matching the CNC program with the changing properties of the cutting process, which allows increasing the processing efficiency while ensuring the required quality of parts, is disclosed. A number of properties of the dynamic cutting system caused by changing trajectory of the longitudinal feed rate of the tool during processing of the shaft, the stiffness change of which is given, are revealed and analyzed.