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

OBRABOTKAMETALLOV Vol. 23 No. 4 2021 TECHNOLOGY from a decrease of -27 % to an increase of 4 %, from a decrease of -73 % to an increase of 16 %, from a decrease of –220 % to an increase of 56 %, from a decrease of –1,040 % to an increase of 256 %. Such a change in the error is explained by possible angular displacements associated with the turning moments of the technological system. During machining with a turning tool located on the transverse carriage, a decrease in the accuracy of the workpiece by one tolerance grade increases the error of the diametrical dimension (in comparison with the base points) with the turning tool located on the longitudinal carriage by 8–20 %. At the same time, a decrease in the accuracy of the workpiece by one tolerance grade for the performed diametrical dimension with a turning tool located on the longitudinal carriage practically affects the diameter error by 28–40 %. The size of the machine tool turret and the coordinates of the tool relative to the center of the turret are also important factors. With an increase in these coordinates relative to the base variant by 2 times and 1.5 times, a change in the error of the formed diametrical dimension, respectively, at the base points, from a decrease by 60 % to an increase by 44 % and from a decrease by 20 % to an increase by 17 % was observed. a b c d Fig. 1 . In fl uence of cutting depths in longitudinal and cross carriages on the value of scattering fi eld of diametrical dimension performed by longitudinal carriage in multi-tool two-carriage processing: a – base variant; b – X 0 = 898.8 mm; c – ITP 1 13; d – ITP 2 13