PROBABILISTIC APPROACH TO CALCULATING THE RATIONAL THICKNESS OF THE TOOL`S CUTTING INSERT FOR HEAVY MACHINE TOOLS

The paper proves that the development of regulations for the operation of cutting tools on heavy machine tools, the formation of objective functions for optimising the parameters of machining parts should be carried out based on a given level of reliability of the cutting tool. In this case, a large number of indicators are used to determine the tool's reliability, durability and maintainability separately. Based on statistical and theoretical studies of the probabilistic nature of the properties of the cutting tool and the parameter of load distribution on it, quantitative dependencies between the parameters of the scattering of properties and the thickness of the tool plate of a prefabricated tool were obtained. The stochastic nature of the machining process on heavy machine tools causes a large dispersion of the properties of the machined and tool materials and other machining parameters. This leads to the need for a probabilistic approach to determining the design and technological parameters of the cutting tool. The reliability of a prefabricated cutter depends on both its load and the bearing capacity of the tool structure, which is the ultimate stress that characterises the strength of the structure. Using a probabilistic approach to calculating the thickness of the cutting plate of the cutters, a correction factor for the thickness was determined taking into account the level of reliability of the tool. The level of reliability was understood as the probability that the maximum stress arising under the action of the load will not exceed the bearing capacity. Typical structures that are most commonly used at modern heavy engineering enterprises were investigated. The law of distribution of cutting forces was determined on the basis of statistical data on the operation of carbide cutters. The thickness of the cutting element was calculated for the Rayleigh load distribution law, determined on the basis of statistical data on cutting forces during turning for different cutter designs. The distribution of the bearing capacity of the tool material of the tool inserts was determined on the basis of laboratory tests.