Vibration Suppression in Turning Using a Kalman Estimator–Based Feedforward Controller

2000 ◽  
Author(s):  
Ameen H. ElSinawi ◽  
Reza Kashani
Keyword(s):  
Machine Tool ◽  
Control Strategy ◽  
Vibration Isolation ◽  
Vibration Suppression ◽  
Control Technique ◽  
Tool Vibration ◽  
Machine Tool Structure ◽  
Transmitted Force ◽  
Workpiece Interaction ◽  
Machine Structure

Abstract Vibration suppression of the tool results in improved surface texture, dimensional accuracy and enhanced productivity in machining operations. The vibration of the machine tool structure, as well as the tool/workpiece interaction are the main contributors to the tool vibration. In light of this, abating the tool vibration can be approached by isolating the tool from the machine structure in the presence of a random process representing the tool/workpiece interaction. An active tool holder capable of isolating the cutting tool from the vibration of the machine tool structure is constructed. Vibration isolation is accomplished by means of a novel, Kalman estimator–based control strategy, a high bandwidth magnetostrictive actuator, and two accelerometers. The proposed control technique focuses on lowering the transmitted force to the tool that is subject to the machine structure vibration (base excitation) in presence of cutting process disturbance. The important aspect of this control strategy is that, while it is designed based on a full order model of the plant, its implementation is reduced to the realization of a second order estimator irrespective of the order of the plant model. Machining experiments showed that up to 30% improvement in surface roughness of the workpiece has been achieved using the proposed technique.

scholarly journals Effects of Design Alterations on the Vibration Suppression of a Machine Tool Structure

2016 ◽  
Vol 15 (3) ◽  
pp. 122-129 ◽  
Author(s):  
Young Jo Kim ◽  
Seung Hoon Ro ◽  
Ho Beom Shin ◽  
Yun Ho Shin ◽  
Keun Sup Jung ◽  
...  
Keyword(s):  
Machine Tool ◽  
Vibration Suppression ◽  
Machine Tool Structure

Vibration Analysis of Radial Drilling Machine Structure Using Finite Element Method

2012 ◽  
Vol 472-475 ◽  
pp. 2717-2721 ◽  
Author(s):  
Rajiv Kumar ◽  
Mohinder Pal Garg ◽  
Rakesh C. Sharma
Keyword(s):  
Machine Tool ◽  
Natural Frequency ◽  
Mode Shapes ◽  
Drilling Machine ◽  
Element Analysis ◽  
Stiffness Matrices ◽  
Machine Tool Structure ◽  
Radial Drilling ◽  
Machine Structure

Manufacturing industries now a days have stringent expectation from the machine tools in terms of productivity as well as quality of products.Vibration plays an important role in determining the quality of product.If the pattern of vibration prevailing in the machine tool during cutting is known,then machine tool structure can be designed in such a way so that natural frequency of machine tool structure can be isolated from the forced frequency.So, this study is focused on finding the natural frequency and mode shapes of radial drilling machine structure.Finite element analysis has been done to find out the natural frequencies and mode shapes of radial drilling machine structure.Assembled mass and stiffness matrices are obtained for each element and solved by using inverse iteration technique.

scholarly journals A Control Strategy of Actively Actuated Eccentric Mass System for Imbalance Rotor Vibration

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 69
Author(s):  
DaeYi Jung
Keyword(s):  
Power Consumption ◽  
Centrifugal Force ◽  
Control Strategy ◽  
Vibration Isolation ◽  
Position Control ◽  
Angular Position ◽  
Fine Tuning ◽  
Control Technique ◽  
Mass System ◽  
Rotor Imbalance

This paper explores the new control strategy of an actively actuated eccentric mass system (AAEMS) for cancelling the rotor imbalance vibration. The AAEMS consists of an eccentric mass with an actuator that actively moves around the circular guided track attached to the rotating rotor thus can generate an effective centrifugal force perpendicular to any tangential direction of the guided circular trajectory. Therefore, once the magnitude and angular position of the inherited static imbalance of the rotor are identified, this actively controlled system can be dispatched to the target angular position(s) where the effective centrifugal force due to rotor imbalance is completely or partially removed. This novel device is currently available and widely used in the vibration isolation problem. However, the study of its control strategy is quite limited, thus, herein, we proposed a new possible control technique, guaranteeing both the robust vibration isolation performance and less control power consumption. To meet such needs, three primary functions of AAEMS are addressed here. First, two (Extended) Kalman filters were employed to sequentially estimate the unknown imbalance of the rotor and the unknown coulomb friction induced between the contact surface of the circular track and the counter-contacted parts of AAEMS. Second, the position control of the AAEMS is achieved by a linear quadratic regulator (LQR)-based optimal control law, simultaneously minimizing the imbalance vibration of the rotor as well as the power consumption of its own actuator. Third, for the situation where the estimation and control errors are presented, thus causing the failure to an acceptable threshold for imbalance vibration, the trial-error-based fine-tuning angular position control was proposed. The effectiveness of the proposed control strategy was evaluated via the simulations and this study shows the practical potential for addressing the AAEMS-based imbalance vibration elimination.

Statistical Analysis of the Dynamic Cutting Coefficients and Machine Tool Stability

1993 ◽  
Vol 115 (2) ◽  
pp. 205-215 ◽  
Author(s):  
M. A. El Baradie
Keyword(s):  
Machine Tool ◽  
Confidence Level ◽  
Cutting Process ◽  
Structure Dynamics ◽  
Cutting Coefficients ◽  
Statistical Variations ◽  
Machine Tool Structure ◽  
Machine Tool Chatter ◽  
Machine Structure ◽  
Tool Chatter

Machine tool chatter is a statistical phenomenon since it is dependent on the interaction of two statistical quantities, these being the dynamic characteristics of the machine tool structure and the transfer function of the cutting process. In this paper, a generalized statistical theory of machine tool chatter has been developed. This takes into consideration the scatter of the dynamic data of the machine structure and/or that of the cutting process. The dynamics of the cutting process have been represented by a mathematical model which derives the cutting coefficients from steady state cutting data, based on a nondimensional analysis of the cutting process. The dynamics of the machine tool structure and the cutting process, being the input data to the theory, were determined experimentally. The predicted stability charts were plotted to take into consideration the scatter in the machine structure dynamics and/or the cutting process. At the threshold of stability, the statistical variations due to the dynamic cutting coefficients amount to ±29.5 percent at 99 percent confidence level, while the statistical variations due to the structure dynamics amount to ±4.5 percent only, at the same confidence level. Therefore, the threshold of stability can be specified only in terms of mean values with confidence limits.

Modal Analysis of the Milling Machine Structure through FEM and Experimental Test

2011 ◽  
Vol 383-390 ◽  
pp. 6717-6721 ◽  
Author(s):  
S. Pedrammehr ◽  
Hamid Farrokhi ◽  
A. Khani Sheykh Rajab ◽  
S. Pakzad ◽  
M. Mahboubkhah ◽  
...  
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Modal Testing ◽  
Machining Process ◽  
Mode Shapes ◽  
Milling Machine ◽  
Machine Tool Structure ◽  
Tool Vibrations ◽  
Machine Structure

Machine tool vibrations have great impact on machining process. In this paper the dynamic behavior and modal parameters of milling machine is presented. For this purpose, the CAD model of the milling machine structure is provided in CATIA and then Natural frequencies and mode shapes of the machine tool structure are carried out through FEM modal analysis under ANSYS Workbench. The model is evaluated and corrected with experimental results by modal testing on FP4M milling machine. Finally, the natural frequencies and mode shapes obtained by both experimental and FEM modal analysis are compared. The results of two methods are in widely agreement.

A Stochastic Approach to Characterization of Machine Tool System Dynamics Under Actual Working Conditions

1976 ◽  
Vol 98 (2) ◽  
pp. 614-619 ◽  
Author(s):  
F. A. Burney ◽  
S. M. Pandit ◽  
S. M. Wu
Keyword(s):  
Machine Tool ◽  
Working Conditions ◽  
Stochastic Approach ◽  
Relative Displacement ◽  
Process Dynamics ◽  
Actual Working ◽  
Machine Tool Structure ◽  
Vertical Milling ◽  
Vertical Milling Machine ◽  
Tool Dynamics

The machine tool dynamics is evaluated under actual working conditions by using a time series technique. This technique develops mathematical models from only one signal, viz., the relative displacement between the cutter and the workpiece. Analysis of the experimental data collected on a vertical milling machine indicates that the new methodology is capable of characterizing the machine tool structure and the cutting process dynamics separately. Furthermore, it can also detect and quantify the interaction between these two subsystems.

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