OPTIMIZATION OF THE NUMBER OF MACHINING STAGES WORKPIECES FOR MECHANICAL ENGINEERING PARTS

The productivity of machining in the production of machine parts is determined by the time spent on shaping surfaces according to the drawing and the number of machining stages required to achieve the specified accuracy of the part from workpieces of varying accuracy. Due to the well-known property of the technological system related to the technological inheritance of errors from the workpiece to the part, the refinement of the workpiece dimensions is carried out in several stages. The required number of machining (refining) stages for the workpiece depends both on the characteristics of the technological system itself and on the degree of variation in the workpiece's input parameters and its machining conditions. In addition, since the process of reducing the workpiece error depends on the dispersion of its dimensions, the required number of machining stages to achieve the specified accuracy is primarily determined by the change in the dimension of the dynamic setup at each stage. At the same time, the dimension itself is typically adjusted by changing the static setup. The dimension of the dynamic setup arises due to the elastic displacements of the elements of the technological system under the influence of cutting forces. The greater the difference between the dynamic setup dimension and the setup dimension (static setup dimension), the larger the error in the resulting dimension. Errors caused by fluctuations in the dynamic setup dimensions are difficult to compensate for, as they depend on many parameters: the strength properties of the material being machined, cutting conditions, cutting tool parameters and its wear, the rigidity of the technological system, and others. The article presents an approach to finding combinations of technological process parameters that ensure the shortest production time for parts and the specified accuracy. For parametric optimization, the identified patterns of the influence of the main technological process parameters on the refinement coefficient of the workpiece dimensions at each machining stage are discussed.