Modal Parameter Estimation of a PVC-product Cleaning Machine by means of Operational Modal Analysis

The prototype of a machine tool for the fine machining of PVC window casings was recently developed and tested. Preliminary tests pointed out that excessive vibrations arise during the execution of some operative motion laws, possibly affecting the product quality. Some structural modification of the machine is thus needed in order to reduce the vibration level. In this context, modal analysis of the machine prototype can be useful to guide the design modifications. In order to excite the system consistently with the operative working conditions, the operational modal analysis was considered more suitable than the traditional experimental modal analysis. The excitation was provided by executing of an impulsive motion law of the machine part hosting the tools, which provides a flat spectrum in the bandwidth of interest. This paper illustrates the main practical aspects of the experimental tests and the results that were obtained by using a commercial software.