MODAL VIBRATION DIAGNOSTICS OF LATHES DESIGNS

In the paper the problem of reasons elucidation in the matter of lathe instability at groove cross turning and boring is solved. As a tool for the analysis of a structure state there are used potentialities of modal monitoring, and in particular, a correlation of modal parameters, sets of proper characteristics of an elastic system (self-frequencies, modal coefficients damping and own forms of vibrations) of lathes designs with the state of bearings in spindle units. The application of a modal approach to the evaluation of a lathe design state or an elastic system is a new section in a dynamic analysis and may be called modal diagnostics. From the analysis of the modal parameter values of a lathe one traces their tie with the lathe design characteristics, and in particular, with the existence of sever rigidity anisotropy of a spindle unit front bearing and also with its insufficient tightness. Reasoning from the information mentioned of the modal parameters connection with the rigidity of a spindle unit front bearing and a state of bearing design the authors draw a conclusion of the technological state of a spindle unit design. In such a way, by the example of the design of two lathes in the paper there is shown a possibility of transition from experimental frequency characteristics through a procedure of modal diagnostics to the evaluation of the technological state of a spindle unit.