Influence of number of rolling elements on vibrations of grinding machines spindle system

Quality and quantity must underpin every productive process.This is even more true in case of manufacture and sale precision steel balls used for bearings. Surface finish improvements have been possible because of constant studies in material science and technological progresses. Those have contributed to raise up the demand. Satisfying the latter implies machines overloading, machinery are required working more and faster. Higher attention should be paid to mechanical components degradation to guarantee this result. Vibrations emitted by machines during working process are identified as the leading causes of premature failure for stressed elements, as bearings. For this reason, a vibrational analysis has been performed on pre-finishing grinding machines. In fact, they sound to be the more exposed to damage due to the type of products entering and process parameters. The goal is searching for mechanical problems that lead to bearings damage in grinding machines. Vibrodiagnostics is a non-destructive technique used to identify causes which result in losses. It is performed with a view of predictive maintenance. This policy pays attention on having the right information at the right time using a condition monitoring equipment. The aim is to anticipate the potential damage, plan the maintenance action with an effort to maximize length and system efficiency. Moreover, a decrease in process and equipment downtime, an increase in components operational life pave the way for a better produced quality. Tests have been performed on rotating machines during working conditions thanks to a data acquisition system SKF Microlog CMXA 75 and a signals analyzer Software CMSW7300-SC-SL, as well as appropriate sensors. The objective pursued by this study include investigating vibration data changes when the number of rolling elements of a bearing changes. In fact, for a given rotational speed, the number of rolling elements is one of the most powerful parameters when determining the bearing vibration frequencies. Velocity and acceleration values of measured points in connection with bearings have been evaluated in time and frequency domains. The aim of measurements is assess machinery vibration status and bearings conditions. In the first part of this thesis values coming from three different machines, which spindle rotational speed is the same, has been considered. Subsequently, attention is paid to only one grinding machine. The intention was to analyze vibrational parameters of spindle bearing systems. The investigation of acquired values and vibration spectra analysis confirmed the diagnostic potential of this machine condition monitoring technique.