Active Vibration Control of Boring Bar Vibrations

Document type: Researchreports
Full text:
Author(s): Linus Andrén, Lars Håkansson
Title: Active Vibration Control of Boring Bar Vibrations
Series: Research Report
Year: 2004
Issue: 7
ISSN: 1103-1581
Organization: Blekinge Institute of Technology
Department: School of Engineering - Dept. of Signal Processing (Sektionen för teknik – avd. för signalbehandling)
School of Engineering S- 372 25 Ronneby
+46 455 38 50 00
http://www.tek.bth.se/
Authors e-mail: lar@bth.se
Language: English
Abstract: The boring operation is a cumbersome manufacturing process plagued by noise and vibration-related problems.
A deep internal boring operation in a workpiece is a classic
example of chatter-prone machining.
The manufacturing industry today is facing tougher tolerances of product surfaces and a desire to process hard-to-cut materials; vibrations must thus be kept to a minimum. An increase in productivity is also interesting from a manufacturing point of view. Penetrating deep and narrow cavities require that the dimensions of the boring bar are long and slender.
As a result, the boring bar is inclined to vibrate due to the
limited dynamic stiffness. Vibration affects the surface finish, leads to severe noise in the workshop and may also reduce tool life.

This report presents an active control solution based on a
standard boring bar with an embedded piezo ceramic actuator;
this is placed in the area of the peak modal strain energy
of the boring bar bending mode to be controlled. An
accelerometer is also included in the design; this is mounted as close as possible to the cutting tool.
Embedding the electronic parts not only protects them from the harsh environment in a lathe but also enable the design to be used on a general lathe as long as the mounting arrangements are relatively similar.
Three different algorithms have been tested in the control system.
Since the excitation source of the original vibrations, i.e. the chip formation process cannot be observed directly, the algorithms must be constructed on the basis of a feedback approach.
Experimental results from boring operations show that the
vibration level can be reduced by 40 dB at the resonance
frequency of a fundamental boring bar bending mode;
several of its harmonics can also be reduced significantly.
Subject: Signal Processing\Active Noise and Vibration Control
Keywords: Active Vibraion Control, Boring Bar Vibrations, Filtered-x LMS
URN: urn:nbn:se:bth-00251
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