Abstract
The article presents a study of the mandrel spindle assembly for accuracy, contact stiffness and strength. The study was made on the basis of conical profile connections with an equiaxed contour. Experiments were carried out for multi-purpose machines of various layouts on the basis of the previously developed program-mathematical complex of evaluating the parameters of the shaft-sleeve coupling. The analysis of the simulation modeling results of the accuracy of the shaft (mandrel) installation in the hole of the sleeve (spindle) is carried out taking into account the error in shape, taper, the magnitude of the assembly force and the external conditional load in the spatial setting. With respect to the three coordinate axes, the possible displacements and rotations of the tool mandrels with a modified shank design are determined when they are based and secured in the spindle. In each design case, the accuracy of the relative position of the parts of the conical profile connections was compared during reusable assembly for the horizontal and vertical machine, respectively, and during the operation of the spindle-mandrel assembly under the condition of an external load. As a result of research, it was found that the layout of the machine does not significantly affect the quality parameters of the profile connection in conditions of reusable assembly. A significant effect of the error in the shape of the mating parts of the connection has been determined, which leads to an increase in maximum contact pressures till 22MPa, a displacement of the mandrel along the Z axis up to 25 µm, and a significant influence on the ultimate external load, which leads to elastic displacements of the mandrel along the Y axis to 2 µm for tapering 1:10.
Highlights
The developed technological support for high-speed milling on CNC machines in [1] made it possible to solve the problem of manufacturing parts of profile connections of a conical shape in longitudinal section, namely: ensuring the quality of manufacturing parts of a conical profile connection with an equiaxed contour corresponding to accuracy 6-8
The calculations determined that the depressions of shaped mandrels are of the same order when compared with traditional round conical connections
The quality parameters of the conical profile connections are affected by the error of the geometrical shape of the mandrels
Summary
The developed technological support for high-speed milling on CNC (computer numerical control) machines in [1] made it possible to solve the problem of manufacturing parts of profile connections of a conical shape in longitudinal section, namely: ensuring the quality of manufacturing parts of a conical profile connection with an equiaxed contour corresponding to accuracy 6-8.Currently, research is being conducted in Russia, as well as in the developed countries of Germany and Japan, in the field of improving the technological equipment of multi-purpose CNC machines [2, 3, 4].The works are aimed at the development and improvement of auxiliary tool designs working in automatic and manual shift conditions.Designs of tool mandrels of the type SK, HSK, PSK, as well as DBT with shanks of a taper of 7:24 and 1:10 of a round cross-sectional shape, as well as a crosssectional profile with various fixing methods in the machine spindle are known.The aim of this work is to assess the quality parameters of auxiliary tool designs of multi-purpose machines made on the basis of conical profile connections of normal and special taper and operated under conditions of reusable assembly-disassembly of the spindle-mandrel connection.As it is known, an assessment of the accuracy position of the connection parts based on the reproduction of the conjugation process applied to conical connections of circular cross-section with a special and normal taper, taking into account the roughness of the parts (shaft) of the connection, assembly force and other factors, is presented in [5, 6]. The aim of this work is to assess the quality parameters of auxiliary tool designs of multi-purpose machines made on the basis of conical profile connections of normal and special taper and operated under conditions of reusable assembly-disassembly of the spindle-mandrel connection. As it is known, an assessment of the accuracy position of the connection parts based on the reproduction of the conjugation process applied to conical connections of circular cross-section with a special and normal taper, taking into account the roughness of the parts (shaft) of the connection, assembly force and other factors, is presented in [5, 6]
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