Full-factor matrix model of accuracy of dimensions performed on multi-purpose CNC machines

Abstract

Introduction. One of the main reasons that modern multi-purpose CNC machines do not use the capabilities of multi-tool processing is the lack of recommendations for design in this direction and, accordingly, for adjustment schemes. The study of the possibilities of multi-tool processing on multi-purpose machines is the subject of the work. The purpose of research: The problem of developing full-factor matrix models of dimensional accuracy and its sensitivity to the machining process is considered to increase the machining efficiency while ensuring machining accuracy using the technological capabilities of multi-tool machining on modern multi-purpose CNC machines. For this purpose, full-factor matrix models of the size scattering fields performed on multi-tool double-carriage adjustments have been developed, taking into account the cases of processing parts with dimensions that differ sharply in different directions, which are often encountered in practice, and in this case, the significant influence of the turns of the workpiece on the processing error, especially in directions with sharply different overall dimensions. Results of research: The developed accuracy models make it possible to calculate not only plane-parallel displacements of the technological system for double-carriage adjustments, but also angular displacements around base points, take into account the combined effect of many factors – a complex characteristic of the subsystems of the technological system (plane-parallel matrix of compliance and angular matrix of compliance), the geometry of the cutting tool , the amount of bluntness of the tool, cutting conditions, etc. As a result, based on the developed accuracy models, it is possible to obtain several ways to control multi-tool machining, including improving the structure of multi-tool adjustments, calculating the limiting values of cutting conditions. Based on the developed full-factor matrix models, it became possible to develop recommendations for the design of adjustments and the creation of an automated design system for multi-tool machining for a group of modern multi-purpose CNC lathes. Scope of the results: The results obtained can be used to create mathematical support for the design of operations in CAD-systems provided for multi-tool multi-carriage machining performed on multi-purpose machines. Conclusions: The developed models and methodology for simulating the machining accuracy make it possible to increase the accuracy and efficiency of simultaneous machining, to predict the machining accuracy within the specified conditions.

Model of Machining Process Control on Multitool Single-Carriage Adjustments

“…One of the most important factors in improving the productivity of the technological process is the concentration of transitions. The highest efficiency of concentration of transition is ensured by its implementation in multi-tool adjustments [1][2][3][4][5][6]. Dimensional accuracy is a paramount requirement in the design, debugging and implementation of the technological process.…”

“…Dimensional accuracy is a paramount requirement in the design, debugging and implementation of the technological process. In the works of Koshin and Yusubov, the principles were formulated and the foundations of the theory of dimensional accuracy design of multi-tool machining were laid [1][2][3][4][5][6].…”

“…Therefore, of particular interest is the current level of mathematical models for the formation of dimensional errors in single-tool and multi-tool adjustments. [1][2][3][4][5][6][7][8][9][10][11].…”

On the Matrix Generalization of the Theory of Machining Accuracy

“…For the obtained dependence (13), linearization is admissible, since 0.5𝜈 << 1, 0.5∆𝑗 << 1 and for cutting edge machining, ∆𝑡/2𝑡 < 1 is true. Therefore, one can write:…”

“…Matrix models. Models of distortion of the performed dimensions (7) of the scattering field (14,15) are built under the assumption that the displacements of technological subsystems in the y direction are formed by the component of the cutting force py, and in the x direction -only px. This assumption is valid for rigid parts of small dimensions and with a ratio of overall dimensions L = D. In general cases, all components of the cutting force affect the coordinate displacements of technological subsystems.…”