Assessment and assurance of CNC machine tools precision

V magistrskem delu je predstavljen postopek preverjanja in izboljšanja natančnosti CNC obdelovalnih strojev. Natančnost CNC obdelovalnih strojev je neposredno povezana tudi z natančnostjo izdelkov, ta je definirana preko pozicijske točnosti in ponovljivosti strojev. Natančnost strojev se običajno preverja v nekih periodičnih časovnih enotah ali po opaženi spremembi geometrijske točnosti izdelkov. To magistrsko delo obsega celovit popis korakov pri preverjanju in izboljšanju natančnosti CNC stružnic. Predstavljeno je začetno stanje takih strojev in na osnovi teh zasnovana procedura za izboljšanje natančnosti in robustnosti doseganja orodjarskih natančnosti (celotno čiščenje CNC stružnice, vključno z zamenjavo stare emulzije z novo, kalibracija roke za umerjanje orodij, preverjanje delovne natančnosti osi in konjička, ter ustrezna korekcija krmilnika). Procedura je bila eksperimenatlno testirana na stružnici Mori Seiki SL-153. Kot rezultat je bila dosežena "obnovitev" stroja iz začetnega razreda točnosti 0,15 mm na končno pod 0,01 mm.This thesis presents a process for assessing and improving the precision of CNC machine tools. The precision of CNC machine tools is directly correlated with the precision of machined products, which is defined by the positional accuracy and repeatability of the machine tools. The precision of machine tools is usually verified in some periodic time units or when a change in geometric precision of the machined products is detected. This study comprises a comprehensive inventory of steps in checking and improving the precision of CNC lathes. The initial condition of such machines is presented, and based on that, a procedure for improving the accuracy and robustness of achieving tool-making precision is designed (complete cleaning of the CNC lathe, including the replacement of old emulsion with a new one, calibration of the removable measuring hand for cutting tool offset measurement, verification of the axis and quill working precision and the corresponding correction of the controller). The procedure was experimentally tested on a Mori Seiki SL-153 lathe. As a result, the restoration of the machine tool from the initial accuracy class of 0.15 mm to a final accuracy of less than 0.01 mm was obtained