• Journal of Industrial Technology
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• v.11
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• pp.115-124
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• 1991

In this study, we design a position controller for two axis servo system. The position controller performs numerical control(NC)to DC or AC servo motor or step motor, and also has a digital input/output sequence capability. The control program composed of position and sequence command, which is called channel, is programmed easily and user-interactively. And it is interpreted and the straight line and arc position command is interpolated. We develop the Z80 microprocessor based system and the software with assembly and C language, and also PC based graphic simulator for the debugging and educational purposes.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.214-219
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• 2001

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. In this study, the compensation device and temperature-based algorithm have been presented in order to compensate thermal error of machine tools under the real-time. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball artifact, and five gap sensors. In order to compensate thermal characteristics under several operating conditions, experiments performed with five gap sensors and manufactured compensation device on the horizontal machining center.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.60-66
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• 2004

Increasing demands on precision machining of 3D free-form surface have necessitated the tool to move smoothly with varying feedrate. To this regard, parametric interpolators such as NURBS (Non-Uniform Rational B-Spline) interpolator have been introduced in CNC machining system. Such interpolators reduce the data burden in NC code, increase data transfer rate into NC controller, and finally give smooth motion while machining. In this research, a new concept to control cutting load in NURBS Interpolator was tried based on the curvature of curve. This is to protect cutting tool, and to have good machinability. For proof of the system, cutting force and surface topography were evaluated. From the experimental results. the interpolator is good enough for machining a free-form surface.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06b
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• pp.1-7
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• 1998

본 연구에서는 3차원 솔리드 모델러로부터 Modeling한 후 제작된 model 에 사용자가 원하는 측정 위치를 지정함으로써 자동적으로 측정용 NC Data를 얻을 수 있는 알고리즘을 설계하고 이를 Program화하였다. 3-D Modeler로서 Unigraphics를 사용하였으며, 공작기계는 FANUC Controller를 장착한 Machining Center이다. 측정용 센서는 접촉식 Probe를 사용하였다. 본 연구를 통하여 CAD시스템에서 구축된 Geomaatric Model로부터 직접 측정을 위한 NC data를 얻고 이 data를 가공후의 측정 Data와 비교하여 봄으로써 제품의 가공정밀도를 확인해 볼 수 있으며, 가공시의 간섭 check, 잔삭가공여유, 과절삭등 다양한 정보를 얻을 수 있을 것이다. 향수 지속적인 연구개발을 통하여 data의 통계처리 및 공작기계의 오차 보정등을 고려하여 줌으로써 기계상에서의 측정 data에 대한 신뢰도를 구축할 수 있을 것으로 사료된다.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.214-222
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• 2003

Studies on the optimization of machining process can be divided into two different approaches: off-line feedrate scheduling and adaptive control. Each approach possesses its respective strong and weak points compared to each other. That is, each system can be complementary to the other. In this regard, a combined system, which is a feedrate control system fur cutting force optimization, was proposed in this paper to make the best of each approach. Experimental results show that the proposed system could overcome the weak points of the off-line feedrate scheduling system and the adaptive control system. In addition, from the figure, it can be confirmed that the off-line feedrate scheduling technique can improve the machining quality and can fulfill its function in the machine tool which has a adaptive controller.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.34-40
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• 2000

최근 CNC에는 또 하나의 전기를 마련할 수 있는 여러 가지 새로운 이슈들이 등장하고 있다. 첫 번째 이슈는 고도로 발달해가고 있는 반도체 산업의 영항으로 CPU의 속도가 기하급수적으로 달라지고 있고 메모리 용량이 상상을 초월할 정도로 급속한 발전을 거듭하고 있다. 이런 환경 속에서 자연스럽게 CNC도 성능이 우수한 하드웨어와 그 성능에 어울리는 고급 소프트웨어 탑재가 요구된다. 두 번째 이슈는 기존의 공작기계에서 생각하지 못했던 개념의 변화이다.(중략)

• Journal of the Korean Society for Precision Engineering
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• v.14 no.1
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• pp.15-16
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• 1997

공작기계의 기본은 POSITION ACCURACY이다. XYZ 3축 직선운동 복합으로 거의 모든 형태를 표현할 수 있다. 3축 각각의 직선운동만 정확하면 정밀한 절삭가공이 된다는 뜻이다. 직선운동의 정확도를 기하기 위하여 볼스크류 를 쓰고 기아도 그라인딩을 한다. POSITION ACCURACY는 NC-CONTROLLER를 사용하면서 극대로 증가한다. 이것이 공작기계의 원리이다. 항공기의 조립은 공작기계가 갖고 있는 X Y Z 3축의 복합만으로는 STROKE가 짧아 표현할 수 없는 상당히 긴 STROKE이면서 공간의 위치가 요구된다. 이를 찾는 방법은 지극히 정밀한 LENS를 동원한 OPTICAL TOOL을 쓰는 것이 가장 용이하다. 항곡부품의 위치도 OPTICAL TOOL을 사용하는 것이 가장 용이하다. 물론 건축용 OPTICAL TOOL보다 항공용은 몇배 더 정밀하다.

• 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.

• IE interfaces
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• v.8 no.3
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• pp.133-139
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• 1995

Free from curves and surfaces are frequently used in designing engineering products such as car, ship, airplane, and hosing of electronic households. In many aspect, it is very nice to use the cutter radius compensation function of CNC controller when contour machining a 2-dimensional curve. However, if the 2D curve is a parametric spline, it is not easy to apply the cutter radius compensation function of CNC controller to the NC data obtained from many commercial CAM system. This is mainly due to the error magnification effect when offsetting line segments with inevitable round-off error at their vertices. Proposed in this paper is an approach to contour machining a 2D parametric spline while using cutter radius compensation. Some implementation results are included.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.4
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• pp.334-343
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• 2001

Polishing a die that has free-form surfaces is a time-consuming and tedious job, and requires a considerable amount of high-precision skill. Some workers tend to gradually avoid the polishing work because of the poor environment caused by dust and noise. In order to reduce the polishing time and cope with the shortage of skilled workers, a user-friendly automatic polishing system was developed in this research. The polishing system with five degrees of freedom is able to keep the polishing tool normal to the die surface. The polishing system is controlled by a PC-NC controller. To easily operate the developed polishing robot system, this study developed an integrated program in the Windows environment. This program consists of four modules: the polishing module, the graphic simulator, the polishing data generation module, and the teaching module. Also, the automatic teaching system was developed to easily obtain teaching data and it consists of a three dimensional joystick and a proximity sensor. The joystick is used to simultaneously drive the polishing system to an arbitrary orientation and the proximity sensor is used to obtain teaching points precisely. Also, to evaluate the stability of the driving program and the teaching system, polishing experiments of a die of saddle shape were carried out.