• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.2
• /
• pp.7-12
• /
• 2008

In the design of modem rotating machinery, it is often necessary to increase the performance of rotor-bearing system. Since a critical speed range influences the performance and safety of the whole system, it should be necessary to constrain the critical speed and thus resonance response in design process to result in large vibration. Consequently the minimization of resonance response amplitudes within the operation range of the rotor system becomes the most primary design objective. In this paper, based on the assumption that the external shape of rotating-shaft, bearing supporting positions and etc, the natural frequency analysis of spindle is performed by ANSYS $10.0^{(R)}$ Optimum design is conducted using the RBF model.

• Journal of Applied Reliability
• /
• v.14 no.4
• /
• pp.208-212
• /
• 2014

An experimental gear-box was set-up to simulate the real situation of the wind-turbine. Artificial cracks of different sizes were machined into the gear. Vibration signals were acquired to diagnose the different crack fault conditions. Time-domain features such as root mean square, variance, kurtosis, normalized 6th central moments were used to capture the characteristics of different crack conditions. Normal condition, 1 mm crack condition, 2mm crack condition, 6mm crack condition, and tooth fault condition were compared using ANFIS and DAG-SVM methods, and three different DAG-SVM models were compared. High-pass filtering improved the success rates remarkably in the case of DAG-SVM.

• Proceedings of the KIEE Conference
• /
• 1997.07f
• /
• pp.2101-2103
• /
• 1997

In this paper, micro step driving method is used for a high performance motion control and minimizing of vibration in a industrial X-Y table. By using a mathmetical analysis method of 2 phase Hybrid-type step motor, each phase current can be optimized about unit speed and torque. We can improve the electrical and mechnical driving charicteristic of machine by applying this proposed driver to the real plant using microprocessor.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.11 no.1
• /
• pp.31-37
• /
• 1991

Acoustic emission(AE) signals detected during metal cutting were applied as the experimental test to sensing tool wear and chipping on the NC vertical milling machine. The in-process detection of cutting tool wear including chipping, cracking and fracture has been investigated by means of AE in spite of vibration or noise through intermittent metal cutting, then the following results were obtained 1) When the tool wear is increased suddenly, or the amplitude of AE signals changes largely, it indicates chipping or breaking of the insert tip. 2) It was confirmed that AE signal is highly sensitive to the cutting speed and tool wear. 3) At the early period of cutting, the wear were large and RMS value increased highly by the influence of minute chipping and cracking, etc. Therefore, the above situations should be considered for the time when the tool would be changed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.05a
• /
• pp.296-303
• /
• 2002

Tribology, in other words, interacting surfaces in relative motion, is essential in life. The relative motion on surfaces may cause some problems with heat, vibration, noise, and so on. Unwanted vibrations by friction, which may arise during the operation of machines, are costly in terms of reduction of performance and service life. All these phenomena inolve stick-slip. The telescopic boom operations involves stick-slip oscillations like slideways. Unwanted stick-slip oscillations on telescopic boom operations cannot achieve smooth sliding and many developers of that machine makes a lot of effort to remove or reduce it. So this paper presents stick-slip oscillation with pressure of the hydraulic cylinder which drives booms, and attempts a theoretical approach for the numerical analysis for its stick-slip condition.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.2
• /
• pp.80-86
• /
• 2002

Previous method of computer simulation to predict the dynamic response of a vehicle has been based on the assumption that vehicle structure is rigid. If the flexibility of the vehicle structure becomes too large to ignore, rigid body assumption will no longer give good estimation of the dynamic characteristics. Therefore, in order to predict more precise vehicle dynamic characteristics, flexible multi-body dynamic analysis of a vehicle is necessary. This paper investigates dynamic characteristics of vehicle systems with flexible frames numerically. Joint reaction forces, vertical accelerations, pitch accelerations are analyzed for the vehicle systems with various flexible frames using multi-body dynamic analysis code and finite element analysis code.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.2
• /
• pp.97-104
• /
• 2000

Pneumatic cylinder is widely used for mechanical handling systems. Often, the impact occurs at the both ends points of pneumatic cylinder and generates destructive shock with in the structural operating members of the machine or equipment. To reduce the damage of system, therefore, shock absorbing devices are required. Cushioning of pneumatic cylinders at one or both ends of piston stroke is used to reduce the shock and vibration. The cylinder body have to withstand under high velocity and load. In this research, the pneumatic cushioning cylinder moving tests have been conducted for different load mass and supply pressure. The velocity of pneumatic cylinder actuation system with multiple orifice cushion sleeve which is set vertically controled with meter-in/out system. This study examines the dynamic characteristics of pneumatic cylinder with cushion devices. It turns out that the cushion pressure is mainly a function of the external load rather than the supply pressure. The cushion region characteristics was also revealed in the meter-in system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.350-354
• /
• 1995

The Tension Leveller of Cold Rolling Mill In POSCO performs levelling the strip in high speed line. But minor variations in operating condition of driving machines such as motor, gear box, and support bearings, a small gap-variation of supporter and strip slip by poor roll revolutions can cause serious problems in the quality of strip. In this study, firstly, A condition monitoring standard for each sensor is made through with the detail analysis of vibration and strip slip. Secondly, An automatic monitoring and diagnosing system was developed to monitor the condition of Tension Leveller, and diagnose the cause of abnormal condition. Finally, A diagnosing algorithm for abnormal condition and man-machine interface (MMI) for easy operation are developed.

• 제어로봇시스템학회:학술대회논문집
• /
• 1994.10a
• /
• pp.522-526
• /
• 1994

There are great needs for checking machine operation status precisely in the iron and steel plants. Rotating machines such as pumps, compressors, and motors are the most important objects in the plant maintenance. In this paper back-propagation neural network is utilized in diagnosing rotating machines. Like the finger print or the voice print of human, the abnormal vibrations due to axis misalignment, shaft bending, rotor unbalance, bolt loosening, and faults in gear and bearing have their own spectra. Like the pattern recognition technique, characteristic. feature vectors are obtained from the power spectra of vibration signals. Then we apply the characteristic feature vectors to a back propagation neural net for the weight training and pattern recognition.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.04a
• /
• pp.788-793
• /
• 1997

The surface,generated by end milling operation, is deteriorated by tool runout,vibration,friction,tool deflection, etc. In many source,deflection of tool affects to surfave accuracy. To develop a surface accracy model,method for the prediction of the topography of machined surfaces has been developed based on models of machine tool kinematics and cutting tool geometry. This model accounts for not only the ideal geometrical surface, but also the deflection of tool resulted in cutting force. For the more accurate prediction of cutting force,flexible end mill model is used to simulate cutting process. Compute simu;ation have shown the feasibility of the surface generation system.