Analog and Digital Approaches of Attenuation Boring Bar Vibrations during Metal Cutting Operations
Blekinge Institute of Technology, School of Engineering, Department of Signal Processing2005 (English)Conference paper (Refereed) Published
In metal cutting operations tool vibration is a frequent problem. Vibrations appear under the excitation applied by the material deformation process during the machining of a workpiece. In order to perform an internal turning or boring operation, e.g. in a pre-drilled hole in a workpiece, it is generally required that the boring bar should be long and slender; therefore it is easily subjected to vibrations. These vibrations will affect the result of machining, in particular the surface finish, and also the tool life may be reduced. As a result of tool vibration severe acoustic noise frequently occurs in the working environment. The vibration problem is to a large extent related to the boring bar low-order fundamental bending modes. In order to control boring bar vibrations in the primary cutting direction an analog and a digital feedback controllers have been used. In both approaches an active boring bar with a built-in actuator has been used. In order to measure the response of the active boring bar, accelerometers are mounted nearby the area, where the excitation force is applied due to material deformation process. This means that in either approach the boring bar vibrations are attenuated actively by the controlled secondary anti-vibrations induced by the actuator. The digital controller, based on the feedback filtered-x LMS-algorithm, manages to reduce the boring bar vibrations in the primary cutting direction by up to approximately 44 dB at the first bending resonance frequency. The analog controller, based on a flexible orthogonal gain and phase lag compensation, results in an attenuation of the boring bar vibrations in the primary cutting direction by up to approximately 40 dB at the first bending resonance frequency. Both controllers also suppress all the harmonics of the first bending resonance frequency. Vibration attenuation performances of the two controllers are compared and discussed.
Place, publisher, year, edition, pages
Active control, boring bar vibrations, metal cutting
IdentifiersURN: urn:nbn:se:bth-9912Local ID: oai:bth.se:forskinfo7090F0652C8E73A7C125706C00237E38OAI: oai:DiVA.org:bth-9912DiVA: diva2:837895
Twelfth International Congress on Sound and Vibration