INITIAL EXPERIMENTS WITH A FINITE ELEMENT MODEL OF AN ACTIVE BORING BAR

• One of the most troublesome sources of vibration in metal cutting is the vibration caused by internal turning operations. A boring bar is a tool holder which is used to machine deep precise cavities inside a workpiece material. In order to perform this internal turning the boring bar usually has a large length-to-diameter ratio, and thus the boring bar vibrations are easily excited by the material deformation process during metal cutting. The vibrations are related to the lower order fundamental bending modes of the boring bar. To overcome the vibration problem an active control technique can be used. In particular, by utilizing an active boring bar with an embedded piezoceramic actuator and a suitable controller, the primary boring bar vibrations originating from the material deformation process may be suppressed with secondary "anti-" vibrations. In order to produce an active boring bar several decisions should be done, i.e. the characteristics of the actuator, the position of the actuator in the boring bar, etc. This usually implies that several prototypes of an active boring bar should be produced and tested, thus the design of an active boring bar is a tedious and costly procedure. Therefore a mathematical model which would incorporate the piezo-electric effect in order to predict the dynamic properties and the response of the active boring bar are of great importance. This paper addresses the development of a "3-D" finite element model of the system "boring bar-actuator-clamping house". The spatial dynamic properties of the active boring bar, i.e. its natural frequencies and mode shapes, as well as the transfer function between the voltage applied to the actuator and acceleration of boring bar are calculated based on the "3-D" FE model and compared to experimentally obtained estimates.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Signalbehandling (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Signal Processing (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Teknisk mekanik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Applied Mechanics (hsv//eng)

Nyckelord

active boring bar

actuator

finite element model

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