A Biaxial Actively Damped Boring Bar for Chatter Mitigation

Redmond, James M.; Barney, P.; Smith, D. A.

doi:10.1515/ijmsp.1999.2.1.1

Cited by 5 publications

(4 citation statements)

References 4 publications

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“…To efficiently use active control to increase system damping, the actuator must be placed at a location which are well matched to the modes to control [6]. A good measure of the effectiveness of an actuator to a given mode is the normalized length of the input shape vector.…”

Section: Application To Critical Speedmentioning

confidence: 99%

Active Control of Magnetically Levitated Bearings

Barney¹,

Lauffer²,

Redmond³

et al. 2001

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This report summarizes experimental and test results from a two year LDRD project entitled Real Time Error Correction Using Electromagnetic Bearing Spindles. This project was designed to explore various control schemes for levitating magnetic bearings with the goal of obtaining high precision location of the spindle and exceptionally high rotational speeds. As part of this work, several adaptive control schemes were devised, analyzed, and implemented on an experimental magnetic bearing system. Measured results, which indicated precision positional control of the spindle was possible, agreed reasonably well with simulations. Testing also indicated that the magnetic bearing systems were capable of very high rotational speeds but were still not immune to traditional structural dynamic limitations caused by spindle flexibility effects.There were three separate papers written on various advanced schemes for levitating the bearing.

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Section: Application To Critical Speedmentioning

confidence: 99%

Active Control of Magnetically Levitated Bearings

Barney¹,

Lauffer²,

Redmond³

et al. 2001

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“…Virtual vibration absorbers were successfully implemented for chatter avoidance in turning by Pratt and Nayfeh (1997. Redmond et al (1999), Browning et al (1997), and Nayfeh (1997, 1999) concluded that biaxial control is necessary to ensure satisfactory chatter suppression. Nachtigal (1972) proposed a feed-forward approach for control of chatter in the lathe and Glaser and Nachtigal (1979) extended it to boring operations.…”

Section: Introductionmentioning

confidence: 99%

“…The resonator is an active vibration absorber tuning achieved by utilizing a simple time-delayed feedback. Redmond et al (1999) proposed a biaxial actively damped boring bar for chatter mitigation. Chung et al (1997) investigated active damping of structural models in high-speed machine tools.…”

Section: Introductionmentioning

confidence: 99%

Time-delay feedback control of lathe cutting tools

Nayfeh

2011

Journal of Vibration and Control

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For some machining operations, tool vibrations decay with time, the trivial solution is a stable equilibrium solution, and hence the machined surface is smooth. For other operating conditions, the trivial solution is unstable and the tool undergoes large oscillations called chatter, which might be periodic, quasiperiodic, or chaotic, and hence the surface finish will not be smooth. Therefore, chatter must be avoided or mitigated to maintain machining tolerances, preserve surface finish, and prevent tool breakage. Therefore, extensive research has been devoted to the understanding of the mechanisms of, modeling of, and methods of controlling machine–tool chatter. In this paper, we show that the region of linearly stable trivial solution can be widened considerably using time-delay acceleration feedback.

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“…Examples of the use of active systems to alter dynamics during machining are relatively few, see Comstock, Tse, and Lemon, 1969, Sadek and Tobias, 1973, Hong-Yeon Hwang, Jun-Ho Oh, and Kwang-Joon Kim, 1988, and Shiraishi, Yamanaka, and Fujita, 1990, General Dynamics Team 1998, and Redmond, Barney, and Smith, 1999. In general, most of these papers address turning, not milling.…”

Section: Introductionmentioning

confidence: 99%

Mitigation of chatter instabilities in milling by active structural control

Dohner

Lauffer

Hinnerichs

et al. 2004

Journal of Sound and Vibration

117

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This report documents how active structural control was used to significantly enhance the metal removal rate of a milling machine. An active structural control system integrates actuators, sensors, a control law and a processor into a structure for the purpose of improving the dynamic characteristics of the structure. Sensors measure motion, and the control law, implemented in the processor, relates this motion to actuator forces. Closed-loop dynamics can be enhanced by proper control law design. Actuators and sensors were imbedded within a milling machine for the purpose of modifying dynamics in such a way that mechanical energy, produced during cutting, was absorbed. This limited the on-set of instabilities and allowed for greater depths of cut. Up to an order of magnitude improvement in metal removal rate was achieved using this system. Although demonstrations were very successful, the development of an industrial prototype awaits improvements in the technology. In particular, simpler system designs that assure controllability and observability and control algorithms that allow for adaptability need to be developed.

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A Biaxial Actively Damped Boring Bar for Chatter Mitigation

Cited by 5 publications

References 4 publications

Active Control of Magnetically Levitated Bearings

Active Control of Magnetically Levitated Bearings

Time-delay feedback control of lathe cutting tools

Mitigation of chatter instabilities in milling by active structural control

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