Document Type : Original Article
Authors
1
Ph.D. Student, Department of Mechanical Engineering, Yazd University, Postal code: 8915818411, Yazd, Iran.‎
2
Mechanical Eng., Faculty of Eng., Yazd University, Yazd, Iran
3
Mech. Eng. Dept., Faculty of Eng., Yazd University, Yazd, Iran
Abstract
Due to its complex nature, the chatter phenomenon in turning processes has always been important for the researchers of machine science and many efforts have been made to control it. Active methods of vibration control have the ability to suppress the vibrations properly in different situations. This paper aims to develop a new, active and economic method for detection and controlling chatter phenomenon before it occurs in the boring process. First, various signal processing methods were briefly reviewed and compared, then two methods which are faster and more accurate in determining the occurrence of chatter were chosen, and the time required for the transition from the stable to unstable mode was determined based on the signals. Then many tests were performed with and without a control system. The accelerometer’s output signal which was measured in 0.1 seconds were used in these tests. Two methods of signal processing (Fourier transform and spectral density) were also applied as indicators of the chatter occurrence at the initial moment. Then, using an active control system, the command was given to slow down the speed of the milling machine to switch the system back to its stable state. Using this control method, many tests were performed with different parameters for boring process. In all tests, when the process was stable, the control system did not enter the circuit, and when the process went into the unstable stage, the chatter phenomenon was detected and controlled in the pre-chatter stage before the surface was damaged.
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