OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 5 No. 2 2023 The values of the main parameters obtained in this way should be reduced to the nearest standard ones. This can be done by slightly changing the position of the boundary line of the minimum values of the dimensional characteristic. The considered graphic-analytical method is implemented in the synthesis of a promising parameteroriented series of vertical milling machines with a cross table (GOST 9726–89). As an analysis of the technical characteristics and operating conditions of domestic milling machines and its foreign counterparts showed, there is a certain correlation between the maximum dimensions of machined parts and the main parameter of the equipment: 1.1059 max 0.4657 b B = ⋅ ; 1.7171 0.0045 b B = ⋅ , (10) where bmax is the maximum width of workpieces to be processed on the machine table; b is an average width of workpieces; B is the maximum width of the working surface of the milling machine. As a result of the data analysis, it was recorded that there is a clear trend towards a decrease in the range of variation in the dimensions of the dimensions of the machined products Rb as the main machine parameter B increases: 1.3027 22082 . b R B = (11) As a result, during the operation of vertical milling machines of the current parameter-oriented series with the denominator j = 1.26 (GOST 9726–89) [87], there is a multiple overlap of individual size ranges, reaching a ninefold value in a certain range of sizes, which, of course, affects the efficiency operating machine tool holding. The new parameter-oriented series has two times fewer members defined by GOST 9726–89, and consists of machines with the following values of the main parameter B: 250; 400; 630(600); 800; 1,000 mm. If you build a parameter-oriented series on the basis of the current one, then the transition to it can be carried out with minor changes in machine-tool production. New are only machines with B = 600 mm, created by minimal modernization of existing standard equipment of similar sizes. Thus, having reduced the range of manufactured and modernized machines, we will be able to increase the serial production of it, reduce current costs for maintenance and repair work, while maintaining the flexibility of the machine tool holding. In order to draw final conclusions about the economic feasibility and efficiency of using the proposed parameter-oriented series instead of the traditional one, it is necessary to determine the values of the reduced costs for both options. It was already noted earlier that, along with the main parameter, it is necessary to optimize other main technical characteristics of the equipment. These include limit values for spindle speeds, permissible torque on it and limits for the use of effective power. Even with a slight change in the structure of the parameter-oriented series, it automatically becomes necessary to change the above characteristics. The substantiation of technical characteristics based on modeling the operational parameters of machine tools using the proposed methodology is described by the authors in [17, 19, 20, 71, 72, 75, 88]. As operational parameters, in this case, the characteristics of the machine drives are considered, the values of which depend on the processing modes, but at the same time lie within the range of technical characteristics. Given that the diameter of the cutting tool (for example, the diameter of the end mill) is in a rigid relationship with the width of the workpiece being processed, the approach to solving this problem is based on the prediction of the distribution of the system of these random variables. The values of the distributions of speeds and cutting forces when the machine performs the specified functions are the initial data that are obtained statistically when processing the relevant information. In turn, the indicators of the distribution of the speeds of the cutting tool used to process the workpiece, and the size of the product being processed, can be calculated from the following dependencies: ln 2 i i a s = ;
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