Development of an active boring bar for increased chatter immunity

The boring operation is prone to chatter as the boring bar is slender and has an overhang. For chatter suppression, passive, semi-active or active control methods can be employed. In the present work, a boring bar has been specially designed to transfer vibration to a cantilever bar surrounded by magneto rheological (MR) fluid. The MR fluid when exposed to electromagnetic flux changes its rheological property within a certain range. Thus, the boring bar is able to exhibit variable damping characteristics by changing the excitation current. The modal parameters are experimentally obtained through an impact test and a shaker test. The variation of modal parameters with excitation current is discussed. A stability lobe diagram is also developed from the model parameters, showing safe and unsafe regions for operation. The semi-active boring bar developed in the present work can be used for the suppression of chatter during the boring operation.

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System Identification for Boring Bar Chatter Control

14th Biennial Conference on Mechanical Vibration and Noise: Vibration and Control of Mechanical Systems ◽

10.1115/detc1993-0235 ◽

1993 ◽

Author(s):

Jonathan A. Embry ◽

Suzanne Weaver Smith ◽

Bruce L. Walcott

Keyword(s):

Aerospace Industry ◽

Low Frequency ◽

Structure Identification ◽

Space Structures ◽

Modal Interactions ◽

Element Analysis ◽

Flexible Space Structures ◽

Boring Bar ◽

Low Frequency Vibration ◽

Chatter Control

Abstract The boring bar is used to provide smooth, accurate cuts in materials. However, when the length to diameter (L/D) ratio of the boring bar becomes large, low-frequency vibration, or chatter, results. Initial attempts to control this unwanted vibration with an active absorber have been successful, but in some configurations problems remain. In this paper, algorithms for flexible structure identification widely used in the aerospace industry are applied to a number of boring bar setups to identify the vibration characteristics of each system. Emphasis is placed on one class of methods which includes the Eigensystem Realization Algorithm (ERA), developed for identification of flexible space structures. The resulting identified characteristics are compared and contrasted. Results are also compared to finite element analysis predictions. From the current identification results, implications for chatter control are discussed, including the possibility of nonlinear modal interactions.

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Dynamic Analysis of Boring Bar for Advancement of Tool Life While Lessen the Machining Time Through FEA

Lecture Notes in Mechanical Engineering - Recent Advances in Mechanical Engineering ◽

10.1007/978-981-15-8704-7_61 ◽

2020 ◽

pp. 501-507

Author(s):

Shweta Sonkar ◽

Prabhat Kumar Sinha

Keyword(s):

Dynamic Analysis ◽

Tool Life ◽

Machining Time ◽

Boring Bar

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Optimal Controller for the Axis Drift in a Precision Boring Bar with Double–Guide Hydraustatic Bearings

International Progress in Precision Engineering ◽

10.1016/b978-0-7506-9484-1.50100-7 ◽

1993 ◽

pp. 870-879

Author(s):

Zhongming Pan ◽

Li Shengyi

Keyword(s):

Optimal Controller ◽

Boring Bar

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A Smart Boring Bar for Compensation of Radial Deformation during Machining

2020 12th International Conference on Measuring Technology and Mechatronics Automation (ICMTMA) ◽

10.1109/icmtma50254.2020.00010 ◽

2020 ◽

Author(s):

Zhang Hongwei ◽

Liu Shuyao ◽

Liu Zhibing ◽

Teng Longlong ◽

Shen Wenhua

Keyword(s):

Radial Deformation ◽

Boring Bar

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A Dedicated Design Strategy for Active Boring Bar

Applied Sciences ◽

10.3390/app9173541 ◽

2019 ◽

Vol 9 (17) ◽

pp. 3541 ◽

Cited By ~ 1

Author(s):

Niccolò Grossi ◽

Lisa Croppi ◽

Antonio Scippa ◽

Gianni Campatelli

Keyword(s):

Operating Conditions ◽

Dynamic Characterization ◽

Control Logic ◽

Boring Bar ◽

Actuation System ◽

Static Equivalence ◽

And Control ◽

Cutting System ◽

Damping Systems ◽

Critical Aspects

Unstable vibrations (i.e., chatter) onset is one of the main limits to productivity in deep boring bar processes. Active damping systems allow to increase machining stability in different configurations (i.e., tool setup), without requiring cutting system dynamic characterization. Design of an active boring bar involves the development of monitoring system (sensors), actuation system and control logic. While several control logics were evaluated and discussed, few design solutions were presented in the literature, focusing only on building prototypes to demonstrate control logic effectiveness. In the presented work, a deep analysis of the main issues and requirements related to active boring design was carried out and a systematic approach to tackle all the critical aspects was developed. The results of the proposed method are: (i) optimal actuators positioning able to damp vibration along two directions; (ii) preload system design guaranteeing the correct actuator preloading for the operating conditions; (iii) covers design to protect actuators and ensure the dynamic and static equivalence between active and standard boring bar. Following this approach, an active boring bar was designed, realized and tested. The results prove the required equivalence between active and original boring bar and assess the damping effect.

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