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

OBRABOTKAMETALLOV Vol. 23 No. 4 2021 TECHNOLOGY Fig. 3. In fl uence of feed and other technological factors on value of scattering fi eld of diametrical dimension performed by longitudinal carriage in multi-tool double-carriage processing. Base variant: cutting depths t 1 = t 2 = 2 mm: a – base variant; b – t 2 = 4 mm a b Fig. 3 shows the in fl uence of feed and other technological factors on the value of the scattering fi eld of the diametrical dimension performed on the longitudinal carriage during multi-tool double-carriage machining. Here, the three pivot points are split like this: ● – s 1 = 0.2 mm/rev, s 2 = 0.2 mm/rev, ▲ – s 1 = 0.2 mm/rev, s 2 = 0.4 mm/rev and ■ – s 1 = 0.2 mm/rev, s 2 = 0.1 mm/rev. The base variant is the same as in Figure 1 and the change is shown for the other option. In the base variant (Figure 3 (a)), it is shown on which branches of the graph these points are located. And the signs of the corresponding form indicate what bene fi t is given by changing the machining conditions for each variant. Variant (b) of Figure 3 shows that multi-tool double-carriage machining at certain values can give lower error values compared to single-tool machining. It has been established that by changing feeds during multi-tool double-carriage machining in comparison with single-tool machining, it is possible to provide higher accuracy. When controlling feeds and changing other processing conditions, it is possible to signi fi cantly reduce or increase the machining error: for point ■ from 42 % to +250 %, for point ● from 2,014 % to + 38 %, for point ▲ from 2,356 % to +1,602 %. Thus, once again we are convinced that the feeds of the carriages during double-carriage machining are an effective management tool. The established operability of the developed models and the total number of factors considered, as a result, make it possible to use it as the basis of a model for managing multi-tool double-carriage machining. Results and its discussion We offer full-factor models of scattering fi elds of the performed dimensions during multi-tool machining on multi-purpose CNC machines. These models take into account the elasticity of the technological system in all 6 degrees of freedom and thus make it possible to take into account both plane-parallel and angular displacements around the base points of the technological system. To check the performance of the models, variants with different initial data that determine the in fl uence of the formula are calculated, that is, theoretical studies of the machining accuracy are carried out for various options. During theoretical studies in the models of distortion and scattering of the performed dimensions in the double-carriage adjustment, the dependences on the technological parameters of both plane-parallel