• Title/Summary/Keyword: Feedrate control

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Reducing the Non Grinding Time in Grinding Operations(1st Report) -Reducing the Air Grinding time using Sound Sensor- (연삭가공에 있어 비가공 시간 단축에 관한 연구(I) -음향센서를 이용한 공연삭 시간의 단축-)

  • KIM, Sun Ho;AHN, Jung-Hwan
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.5
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    • pp.85-91
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    • 1997
  • Air grinding time in grinding process has a great effect on its efficiency due to low feedrate. This paper presents a reduction methos of air grinding time in cylindrical plunge grinding operation. Tje reduction of air grinding time is accomplished by finding the distance between contact point and rising point of ultra- sonic signal of the grinding wheel to workpiece. It uses a variation of sound signal generated by the flow of coolant when the grinding wheel approaches to workpiece. The ultrasonic sensor with 23 kHz center fre- quency and 8 kHz bandwidth is used to find the nearest approaching point(NAP). Monitoring and control system of the grinding conditions is implemented with CNC controller to control feedrate override and ultrasonic sensor to find NAP. The experimental result shows that the ultrasonic signal is a good measure- ment to find NAP. But it needs the considerations for the effect of the relationship between flowrate of coolant and diameter of workpiece.

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Adaptive Control Constraint System through Current Monitoring of Spindle in NC Lathe Process (NC 선반공정에서 주축 전류 모니터링을 통한 구속적응제어 시스템)

  • 신동수
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1999.10a
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    • pp.27-33
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    • 1999
  • In order to regulate cutting force at a desired level during NC lathe process, a feedrate override Adaptive Control Constraint system was developed. Nonlinear model of the cutting process was linearized as an adaptive model with a time varing process parameter. Performance of the ACC system was confirmed on the NC lathe equipped with the developed NC system through a large amount of experiment.

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A Newly Developed KIMMBOT II Controller (KIMMBOT II 제어기의 재구성)

  • Yea, I.T.;Kim, S.I.
    • Proceedings of the KIEE Conference
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    • 1988.07a
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    • pp.986-989
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    • 1988
  • The new controller which conststs of IBM-PC/AT, SBC, servo module and motor driver has been developed for KIMMBOT II robot. The servo module which controls two axes at the same time also has beendeveloped. This module inputs relative number of pulse and feedrate via multbus, after then outputs analog command voltage with reference to feedback pulses from the encoder of a motor. This system has a great flexibility. The reduction of parts gives more reliability.

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Digital Contouring Control of Biaxial System (2축 디지틀 윤곽제어)

  • Lee, Gun-Bok;Ko, Tae-Geun
    • Proceedings of the KIEE Conference
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    • 1998.11b
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    • pp.435-437
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    • 1998
  • In this productive system, it needs to control the each axis motion harmoniously to perform accurately for the manufacturing, transporting and printing. Independent Axis Control usually used for this objection. However, if Independent Axis Control mismatched the parameter of each axis system or in the case of free curve tracking or the case of high speed control, there would be big contour error so that cannot achieve control objection. As a result, there is Contour Control method suggested to supply for this defect. This paper carried modeling of biaxial system and implemented Independent Axis Control & Contouring Control on straight line, circular, and coner path by simulation and experiment. If feedrate increased, contour error growed. In consequence, according to this factor, we introduced contouring controller, so we could find the fact that contour error was reduced more than that of independent axis control about each path.

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Adaptive Control of End Milling Machine to Improve Machining Straightness (직선도 개선을 위한 엔드밀링머시인 의 적응제어)

  • 김종선;정성종;이종원
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.5
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    • pp.590-597
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    • 1985
  • A recursive geometric adaptive control method to compensate for machining straightness error in the finished surface due to tool deflection and guideway error generated by end milling process is developed. The relationship between the tool deflection and the feedrate is modeled by a modified Taylor's tool life equation. Without a priori knowledge on the variations off cutting parameters, time varying parameters are then estimated by an exponentially windowed recursive least squares method with only post-process measurements of the straightness error. The location error is controlled by shifting the milling bed in the direction perpendicular to the finished surface and adding a certain amount of feedrate with respect to the tool deflection model before cutting. The waviness error is compensated by adjusting the feedrate during machining. Experimental results show that location error is controlled within a range of fixturing error of the bed on the guideway and that about 60% reduction in the waviness error can be achieved within a few steps of parameter adaption under wide operating ranges of cutting conditions even if the parameters do not converge to fixed values.

Control Gain Tuning of a Simultaneous Multi-Axis PID Control System by Taguchi Method (다구찌방법을 이용한 다축 동시 PID 제어시스템의 제어이득 조정)

  • Lee, Ki-Ha;Kim, Jong-Won
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.6
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    • pp.25-35
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    • 1999
  • This paper presents a control gain tuning scheme for multi-axis PID control systems by Taguchi method. As an experimental set-up, a parallel mechanism machine tool has been selected. This machine has eight servodrives and each servodrive has four control gains, respectively. Therefore, total 32 control gains have to be tuned. Through a series of design of experiments, an optimal and robust set of PID control gains is tuned. The index of the sum of position error and velocity error is reduced to 61.4% after the experimental gain tuning regardless of the feedrate variation.

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Cutting Force Control by Using an Adaptive Robust Controller (견실한 적응 제어기를 이용한 절삭력 제어)

  • Kim, J.W.;Kim, T.Y.
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.4
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    • pp.55-66
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    • 1995
  • This paper presents an explicit pole-assignment adaptive servocontrol shceme and its application to cutting force regulation for feedrate maximization. The controller structure of the suggested adaptive control scheme is based on robust control theory. This controller structure is then combined with an on-line model estimation algorithm. The whole scheme is applied to a milling process control. The results of real time cutting experimental studies show that the asymptotic regulation of milling peak cutting forces can be achieved with robust- ness against the time varying perturbations to the process model parameters, which are caused by nonlinear cutting dynamics.

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Operating Method of Network Interpolation for Motion Control Device (모션 제어장치의 네트워크 보간 운전방법)

  • Kwak, Gun-Pyong
    • Journal of Institute of Control, Robotics and Systems
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    • v.8 no.8
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    • pp.713-718
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    • 2002
  • Motion controllers are essential components for operating industrial equipments. Compared with general industrial controllers, motion controllers allow motion control requiring greater speed and precision. This paper presents a method for controlling multi-axes motors via industrial networks. To achieve a line or arc interpolation, the master system delivers instructions to slave systems connected to the network. The network instruction transmitted from the master controller is re-interpolated by the individual slaves through sub-interpolators. The re-interpolated feedrate information is transmitted to the motion control loop in which the current position and the reference position are then calculated. In this way, the interpolation driving between control units is achieved via industrial networks.

simultaneous Control of Position and Cutting Force Based o Multi-input Multi-output Model in Ball End Milling Process (볼엔드밀 절삭공정에서 위치 및 절삭력 동시제어)

  • 이건복
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.04a
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    • pp.121-126
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    • 2000
  • This research proposes a new advanced control method and demonstrates its realization in part. By incorporating shape machining and cutting force control at a time, this integrated scheme makes it possible to machine a desired shape and avoid the trouble of programming feedrate and spindle speed before machining and also reduce the shape error. The main idea proposed to achieve those goals consists in giving commanded path and desired cutting force at the same time. which makes it possible for position and force controller to distribute the corresponding velocity of individual axes and main spindle by an appropriate interpolation. That indicates we can replace the built-in interpolator of commercial machine tools by the developed algorithm.

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Adaptive Control for Cutting Force Regulating in Turning Operation (선삭가공에서 절삭력을 일정하게 유지하기 위한 적응제어)

  • 노상현;김진락;김교형
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.1
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    • pp.69-77
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    • 1993
  • Adaptive Control is applied to regulate cutting force in turning operation under varying cutting conditions. Regulation is achieved primarily by adjusting feedrate. Such control leads to better machine utilization and increased tool life. The modeling of adaptive control system in turning operation is presented. The experimental results show that the adaptive PI controller is stable and performs more effective force control over wide range of cutting conditions as compared with the fixed gain PI controller.