• Journal of the Korean Society for Precision Engineering
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• v.14 no.9
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• pp.52-60
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• 1997

This paper proposes the effective method of the software based motion control by using lenear, exponential and bell type discrete filters for acceleration and deceleration of servo motors. Recursive filters are designed in discrete time domain which can reduce computation time and vibration of motors due to load disturbance. Also it deals with the method which decides the time constants of filters when a machine tool is driven at rapid, cutting and jog feedrate. Validity of the proposed method is verified by corner cutting experiments.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.370-375
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• 2004

This paper presents an accurate cutting simulation and feedrate scheduling system for CNC machining. This system is composed of a cutting simulation part and a feedrate scheduling part. The cutting simulation part computes the geometric informations and calculates the cutting forces in CNC machining. The cutting force model using cutting-condition-independent coefficients was introduced for flat end milling and ball end milling. The feedrate scheduling part divides original blocks of NC code into smaller ones with optimized feedrates to adjust the peak value of cutting forces to reference forces. Some machining examples show that the developed system can control the cutting force at desired levels.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.206-214
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• 1988

To improve the surface waviness in the peripheral milling, the feedrate is controlled so that the cutting force measured in the normal direction to the workpiece is constant. A discrete time first order model between the feedrate and the tool deflection is derived for the control. It has been shown by the analysis that the tool deflection is directly related to the feedrate and largely affects the surface waviness during cutting. The experimental results shown that the surface waviness is drastically improved by the proposed methods.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.708-713
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• 2000

A research on the AFC(Auto Feedrate Control) by a fuzzy controller using a tool dynamometer and motor currents was conducted. For simulations, cutting dynamics of end-milling process was modeled by geometric relationship between tool and work-piece. The fuzzy logic controller was employed to track the desired cutting force and showed good performance in simulations and several experiments. The spindle motor currents was modeled to estimate cutting force and successfully used for the AFC.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.457-458
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• 2009

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.71-81
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• 2000

This paper describers a look ahead algorithm of PC-NC(personal computer numerical control). The algorithm is based on acceleration/deceleration before interpolation which doesn\`t include a command error and determines a feedrate value at the end point of each block(or start point of each block). The algorithm is represented as following; 1) calculating two maximum arrival feedrates(F$_1$,F$_2$) by an acceleration value, a command feedrate, and the distance of a NC block, 2) getting a tangent feedrate (F$_3$) of the adjacent blocks, 3) choosing a minimum value among these three feedrates, and 4) setting the value to a feedrate of a start point of the next block(or a end point of the previous block). The proposed look ahead algorithm was implemented and tested by using a commercial TROS(real time operation system) on the MS-Windows NT 4.0 in a PC platform. For interfacing to a machine, a counter board, a DAC board and a DIO board were used. The result of the algorithm increased a machining precision and a machining speed in many short blocks.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.5 no.2
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• pp.63-72
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• 1996

In order to regulate the cutting force at a desired level during peripheral end milling processes a feedrate override Adaptive Control Constraint (ACC) system was developed. The feedrate override function was accomplished through a development of programmable machine controller (PMC) interface technique on the NC controller, Nonlinear model of the cutting process was linearized as an adaptive model with a time varying process parameter. An integral type estimator was introduced for on-line estimation of the cutting process parameter, Zero order hold digital control methodology which uses pole-assignment concept for tuning of PI controllers was applied for the ACC system. Performance of the ACC system wsa confirmed on the vertical machining center equipped with fanuc OMC through a large amount of experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.690-694
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• 1996

In order to regulate the cutting force at a desired level during peripheral end milling processes, a feedrate override Adaptive Control Constant system was developed. This paper presents an explicit pole-assignment PI-control law through spindle motor current monitoring and its application to cutting force regulation for feedrate optimization. An experimental set-up is constructed for the commercial CNC machining center without any major changes of the structure. A data transfer system is constructed with standard interface between an IBM compatible PC and a CNC of the machining center. Experimental results show the validity of the system.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.232-236
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• 1987

To improve the surface waviness in the peripheral milling, since the tool deflection is largely affected by cutting force, the feedrate is controlled so that the cutting force measured in the normal direction to the workpiece is constant. A discrete time first order model between the feedrate and the tool deflection is derived for the control. The experimental results show that the surface waviness is greatly improved by the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.9-20
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• 1998

In recent manufacturing process, the increase of productivity has been attempted by reducing machining time with the increase of cutting force. However, the excessive increase of cutting force can cause tool breakage and have a bad effect on both manufacturing machine and workpiece. Thus, it is necessary to estimate and control the cutting force in real time during the process. In this study, use of disturbance observer is proposed for the indirect cutting force estimation. The estimated cutting force is used for the real-time control of feedrate, making the actual cutting force follow the reference force command. Since the suggested method does not need an expensive sensor like a dynamometer, the method is expected to be used practically. Since the actual cutting force follow the reference force, resulting the reducing of the machining time the increase of productivity are also expected, and the quality of cutting surface has been improved due to the adjusted feedrate. Besides, an actual constant cutting force guarantees the prevention of tool breakage. To show the effectiveness of the suggested cutting force control method, an experimental setup has been made without sensor and applied to several workpieces. Experiments show that the suggested method is effective to cutting force control of a CNC machining center.