• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.471-474
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• 2004

In this paper, a NURBS surface interpolator is proposed which can deal with shapes defined from CAD/CAM programs on a surface basis and can improve contour accuracy. The proposed interpolator is based on newly defined G-codes and includes online tool-path planning suitable for NURBS surface machining. The real-time interpolation algorithm, considering an effective machining method for each machining process and minimum machining time, is executed in an online manner. The proposed interpolator is implemented on a PC-based 3-axis CNC milling system and evaluated through actual machining in terms of machining time and regulation of feedrate and cutting force in comparison with the existing method.

• 한국공작기계학회논문집
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• 제12권3호
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• pp.75-81
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• 2003

Pocket machining is metal removal operation commonly used for creating depressions in machined parts. Numerically controlled milling is the primary means for machining complex die surface. These complex surfaces are generated by a milling cutter which removes material as it traces out pre-specified tool paths. To machine, a component on a CNC machine, part programs which define the cutting tool path are needed. This tool path is usually planned from CAD, and converted to a CAM machine input format. In this paper I proposed a new method for generating NC tool paths. This method generates automatically NC tool paths with dynamic elimination of machining errors in 2$\frac{1}{2}$ arbitrary shaped pockets. This paper generates a spiral-like tool path by dynamic computing optimal pocket of the pocket boundary contour based on the type and size of the milling cutter, the geometry of the pocket contour and surface finish tolerance requirements. This part programming system is PC based and simultaneously generates a G-code file.

• 한국기계가공학회지
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• 제3권4호
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• pp.20-29
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• 2004

A Tool wear monitoring system is indispensable for better machining productivity with guarantee of machining safety by informing the tool changing time in automated and unmanned CNC machining. Different from monitoring using other signals, the monitoring of spindle current has been used without requiring additional sensors on machine tools. For the reliable tool wear monitoring, current signal only of tool wear should be extracted from other parameters to avoid exhaustive analyses on signals in which all parameters are fused. In this paper, influences of force components of parameters on measured spindle current are investigated and a hybrid approach to cutting force regulation is employed for tool wear signal extraction in the spindle current. Finally, wear levels are verified with experimental results by means of real-time feedrate aspects changed to regulate the force component of tool wear.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.225-226
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• 2007

• 한국정밀공학회지
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• 제6권4호
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• pp.21-31
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• 1989

역사적으로 CNC기술이 생산성향상에 기여한바는 매우 크다. 최근에는 고도의 생산성을 추구하는 CNC공작기계는 수요자들의 요구에 부응하여 관련업계는 CNC 기술의 발전을 더욱 가속화 시키고 있다. 오늘날의 CNC는 더욱 향상된 Computer Architecture에 적합한 Software System과 고속, 고집적의 소자기술을 결합한 것이라 볼 수 있으며, 그 결과는 생산을 자동화 하고 전체를 하나의 system화 하려는 요구에 부응하고 유연(Flexible)하며, 사용하기에 편리하고(User-friend- ly), 신뢰성과 높은 생산성을 갖추고 있다. 새로운 CNC 기술이 요구되는 응용분야는 고도로 자동 화 되고 결합 된 FMS에서 부터 단축제어용에 이르기까지 매우 광범위하다. 3축의 Milling, 6축 Machining Center, 전용기 등 Stand-alone 기계들을 위주로한 중소형기계 공장에 적합한 CNC 기술이 개발되고 있는 동시에 CELL LEVEL, 좀더 큰 규모의 FMS 또는 그 이상으로 자동화된 system을 구성하 기 위하여 많은 새로운 기능이 요구되고 종래의 CNC와는 다른 역할의 변화가 필요하다. 실제로는 많은 경우에 이러한 두가지의 응용이 공존하고 있으며, CNC의 기능이나 성능을 희생하지 않고 동일한 Hardware로 여러가지의 응용을 만족시켜야 한다. 생산공정과 생산기술의 변화가 반영되어야 하며, Control 기술도 변화하고 있다. 유연하고 확장가능한 Software, Hardware 구조의 CNC가 실제적으로 가장 Cost-effective한 해결책이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.975-978
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• 2001

For machining auto-mobile cam, the developed biarcs-fitting method eliminates the ridge problems in conventional straight-line fitting approximation or single-arc fitting of curve tool path where it leaves ridges of tool marks on the machined surface of the workpiece. The powerful advantage of this biarc method is demonstrated by applying it to the numerically controlled machining of a curved cam profile, also verified by using a CNC simulating program for auto-mobile cam profile. As a result, this algorithm may be used in CNC milling and turning for cam profile machining with short block line.

• 동력기계공학회지
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• 제5권2호
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• pp.43-49
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• 2001

For machining auto-mobile cam, the developed biarcs-fitting method eliminates the ridge problems in conventional straight-line fitting approximation or single-arc fitting of curve tool path where it leaves ridges of tool marks on the machined surface of the workpiece. The powerful advantage of this biarc method is demonstrated by applying it to the numerically controlled machining of a curved cam profile, also verified by using a CNC simulating program for auto-mobile cam profile. As a result, this algorithm may be used in CNC milling and turning for cam profile machining with short block line.

• 한국정밀공학회지
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• 제15권10호
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• pp.180-192
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• 1998

This paper introduces a new self-organizing fuzzy logic controller (SOFLC) for precision contour machining in the presence of large disturbances which adjusts both input and output membership functions simultaneously. The parameters of the proposed controller are self-tuned in real-time according to a continuous measurement of the performance of the controller itself and estimated disturbance values. The proposed controller as well as a conventional fuzzy logic controller and a PID controller were simulated and implemented on a 3-axis milling machine in contour milling. Both the simulations and experiments show that the self-organizing fuzzy logic controller has superior performance in terms of contour tracking accuracy compared with the other two controllers.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.653-657
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• 1996

This paper presents adaptive cutting force control in milling process using indirect cutting force measurement. The cutting forces in X, Y, and Z axes are measured indirectly from the sensing current of the feed-drive servo motor. After modelling the feed-drive system of a horizontal machining center, the relation between the cutting force and the servo motor current is analyzed. The pulsating milling forces are measured from the sensing current within the bandwidth of the servo. It is shown that indirect cutting farce measurement can be used in adaptive cutting force control. The adaptive control scheme which is globally convergent and stable is attached to a commercial CNC machining center. Cutting experiments on end milling are performed for diagonal cutting.