An experimental analysis of damped coupled vibrations in broaching

The paper reports for the first time aspects related to dynamics of broaching when features with complex geometries are generated. It describes an experimental analysis of causes and outcomes of damped-coupled vibrations when broaching semi-closed profiles, i.e. dovetails of gas turbine engines disks. Singular indentations or groups of tilted chatter marks were found in particular zones on broached surfaces. Analysis of force and acceleration signals revealed that damped-coupled vibrations that result in tilted chatter marks mainly occur due to specific geometry of cutting edges that enable coupling of three-dimensional (3D) vibrations. A new method to detect the appearance of tilted marks as a result of damped-coupled vibrations with particular frequency has been proposed by monitoring the elliptical movement of cutting edge via time and frequency domain analysis of two acceleration signals.