Chatter is a self-excited vibration that can occur during machining operations and become a common limitation to productivity and part quality. For this reason, it has been a topic of industrial and academic interest in the manufacturing sector for many years. A great deal of research has been carried out since the late 1950s to solve the chatter problem. Researchers have studied how to detect, identify, avoid, prevent, reduce, control, or suppress chatter. This paper reviews the state of research on the chatter problem and classifies the existing methods developed to ensure stable cutting into those that use the lobbing effect, out-of-process or in-process, and those that, passively or actively, modify the system behaviour.

Chatter in machining processes: A review

Chatter suppression techniques in metal cutting

On-line chatter detection and identification based on wavelet and support vector machine

Improvement of chatter stability in boring operations with passive vibration absorbers

The industrial robot, due to its flexibility, is considered as a promising option to accomplish the fine boring work of the aircraft intersection holes. However, the robot has a relatively low stiffness and is easily subjected to chatter vibration in the boring process, resulting in difficulty in guaranteeing the machining quality. In this article, the mechanism of the vibration in the robotic boring process is analyzed, and a novel vibration suppression method based on the pressure foot is proposed. First, a robotic boring system is presented. Based on its cutting characteristics and stiffness characteristics, the mechanism of the vibration is analyzed, followed by the study of the tool path during the boring operation. It is found that in the robotic boring process it is the robot itself vibrates rather than the boring bar, which usually vibrates in the traditional CNC machine tools. And the type of the vibration is found to be a forced vibration with a displacement feedback. Furthermore, a novel method making use of the pressure foot is proposed to suppress the vibration of the robot. Finally, large numbers of boring experiments have been conducted and the results verify the correctness of the vibration mechanism and the effectiveness of the vibration suppression method.

Vibration analysis and suppression in robotic boring process

Magnetorheological fluid-controlled boring bar for chatter suppression

An innovative chatter suppression method based on a magnetorheological (MR) fluid-controlled boring bar for chatter suppression is developed. The MR fluid, which can change stiffness consecutively by varying the strength of the applied magnetic field, was applied to adjust the stiffness of the boring bar and suppress chatter. The cutting dynamic stability under different natural frequencies of the structure was analyzed by an energy method, which shows that cutting dynamic stability depends on both the natural frequency of the structure and the spindle speed. The chatter suppression mechanism with varying natural frequency is analyzed for further parameter optimization. Furthermore, both theoretical analyses and numerical simulations indicate that a square wave exciting current with a large amplitude and a moderate frequency has a better effect on regenerative chatter suppression. Experiments utilizing a MR fluid-controlled boring bar under an exciting current with different waveforms and frequencies were conducted. The experimental results show that the chatter can be significantly suppressed using MR fluid-controlled boring bar under a square wave exciting current with a frequency of 4–6 Hz and an amplitude of 0–2 A.

Parameter optimization of time-varying stiffness method for chatter suppression based on magnetorheological fluid-controlled boring bar

The utility model discloses a mini automobile magnetic rheologic intelligent vibration damping device. Air diaphragms are arranged in a hole of one end of a working cylinder to form a combined energy storage air bag with a base cavity, and the bottom surface of a base is provided with screwed holes for installing one-way valves; magnetic rheologic material is filled inside the working cylinder, and the working cylinder is divided into two working cavities by a piston; the outer wall of the piston and the inner wall of the working cylinder form an annular damping passage which is connected with an upper cavity and a lower cavity of the working cylinder; the other end of the working cylinder is tightly sealed by a top cover; one end of the piston is provided with an annular groove, two opposite end surfaces of the annular groove are inclined surfaces, and an excitation coil is wound inside the annular groove; besides, three guiding sliding blocks made of non-magnetic conductive material are respectively embedded into the outer surface of the piston at intervals of 120 DEG. The utility model reduces magnetic leakage and raises magnetic field utilization ratio; the utility model uses the combined energy storage air bag, therefore the utility model has the advantages of simple installation, long service life, good damping characteristic and simple and compact structure. When a controller is matched, the utility model can regulate automatically the damping characteristic according to actual road conditions to achieve the intelligent vibration damping effect of mini automobiles.

Minisize-automatic magnetic-current variation intelligent shock-adsorption device

In the structure of Magnetorheological (MR) intelligent damper, the magnetic system is a pivotal part. It has direct influence on the damper's performance. In order to optimize damper's magnetic system, the parameter model of magnetic system was established, which included many factors such as radius of piston rod, radius of piston, number of coil, thickness of piston cylinder, gap length of the annular orifice, and effectual length of the annular orifice. Then the optimal model of magnetic system was established, which was based on the characteristic equation of MR fluid, the mechanical model of damper, the restrained dimension of damper's structure and the parameter model of magnetic system. And the optimal model was solved based on the large-scale optimizing algorithm. The optimized result was validated by FEM analysis. The results show that the optimizing method of magnetic system for MR intelligent damper is accurate and effective.

Tianrong Kong

Papers

Magnetorheological fluid-controlled boring bar for chatter suppression

Parameter optimization of time-varying stiffness method for chatter suppression based on magnetorheological fluid-controlled boring bar

Minisize-automatic magnetic-current variation intelligent shock-adsorption device

Optimal design of magnetic system for the magnetorheological intelligent damper