• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.157-163
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• 1995

This paper presents an algorithm to deternine the tool path height for rough machining of sculptured surface. To minimize rough machining of sculptured surface, it is necessary to determine the tool path heights of contour planes. the proposed algorithm searches for the height at which maximum metal removal rate is obtained. This bisection method is accomplished until all shoulder heights are within roughing tolerance. The machining experiment demonstrates the superiority of the algorithm presented in this thesis.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.47-54
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• 1999

Tool wear is one of major causes occurring defectives in NC machining. In this paper we developed an automatic tool compensation system for the NC lathe machining. The system compensates machining error without any help of operators whenever the specification of a part is out of a tolerance. The configuration of the automatic compensation system consists of a NC lathe, an autoloader, a sensor, and a PLC. The system is operated as follows. A workpiece loaded by the autoloader is machining on the NC lathe. Once the workpiece is machined to be turned to a part, it is moved onto the sensor to be measured. If the sensor detects a part out of tolerance, a tool compensation is made in the NC controller. The system gives a help in increasing the productivity by reducing occurrence of defective parts as well as by eliminating time for the tool compensation. Besides the productivity increase, the system calculates cumulative usage time of the tool and notices the tool replace time to a worker by an alarm signal. A case is introduced to show that the system can be applied effectively in a shop.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.1
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• pp.60-68
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• 2004

The purpose of this paper is to establish an effective inspection system by using OMM (On-Machine Measurement) system based PC-NC. This system can reduce manufacturing lead time because a workpiece is inspected at every machining process and the manufacturing system which includes inspection faculty is able to realize on-line process on CNC machining center. The proposed OMM system is composed of a few algorithms for determination of inspection parameters. It is accomplished by determining the number of measuring points, their location, measuring path using fuzzy logic, Hammersley's method, TSP (Traveling Salesperson Problem) algorithm. The inspection feature applied to this system is based on machining feature. This method is tested by simulation and experiment that are analyzed measuring data and geometry tolerance.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.61-68
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• 1998

The form accuracy of parts has become an important parameter. Therefore, dimensional tolerance and geometric tolerance are used in the design stage to satisfy required quality and functions of parts. But the informations on the machining conditions, which can satisfy the assigned geometric tolerance in design, are insufficient. The objectives of this research are to study the effects of the grinding parameters such as traverse speed, work speed, depth of cut, and dwell time on the after-ground workpiece shape, and to find out the major parameters among them. The results are as follows, The effects of work speed and depth of cut on workpiece shape are negligible compared with the effect of traverse speed. There is an optimal dwell time depending on the traverse speed. The optimal dwell time is decreasing as the traverse speed is increased.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.34-41
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• 2003

This paper suggests a methodology fur improving the machining accuracy by compensating for the machining errors based on on-machine measurement process. Probing errors and machine tool errors included in the measurement data were calibrated or compensated to obtain the actual machining errors. Machine tool errors were modeled in forward and backward directions according to the axis movement direction to consider the effects of backlash errors on the measurement data, and model parameters were determined by measuring a cube array artifact. A rectangular workpiece was machined and then measured with a touch probe as a verification experiment. Machining experiments showed that the machining errors were reduced to within the designated tolerance after compensating for the actual machining errors by modifying the original footpath for the next-step machining.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1542-1551
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• 1990

This paper shown how to measure the machining error in diameter of cylindrical workpiece and compensate the measured machining error in NC turning. Machining error is measured by the electric micrometer mounted on the tool post with the NC part program for probe location path analyzed. Correct NC part program for finish turning is automatically generated to compensate the measured machining error. These concepts have been effectively introduced to a newly developed software for error compensation. In turning experiments with the developed error compensation system, machining error was almost within the specified tolerance, which reveals the effectiveness of the developed system.

• Journal of Korean Society for Quality Management
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• v.26 no.1
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• pp.172-191
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• 1998

In this paper, dimension tolerance design for components is studied. Three cost factors are considered: machining cost, rework cost, and loss related to product quality which is affected by the tolerances of components. We propose a procedure to determine the optimal tolerances of components and a, pp.y the procedure to design the tolerances of fine motion stage in semicoduct machine. We compare the proposed procedure with the existing model for determining tolerance economically.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.1
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• pp.92-100
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• 1994

For generating NC machining data automatically, it is important to handle computer models such as geometric shape data including engineering specifications for the mechanical part to be manufactured. We proposed unique CAM system for a personal computer that can define the geometric shape in an ease manner and machine the sculptured surfaces of a mold cavity. In this paper, the theoretical basis of generation of high precision machining data for a mold cavity is obtained. The first is geometric modelling, and the second is high precision machining with an optimized tool path algorithm satisfying given tolerance limits. Especially, the bicubic Bezier basis function is adopted for a geometric modelling.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.3
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• pp.468-484
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• 1992

본 연구에서는 기존의 유연 볼 엔드밀의 절삭력 모델을 바탕으로 자유 곡면의 정삭 가공에서 발생할 수 있는 과대 또는 과소 절삭을 방지하면서 그 가공의 효율성을 높이기 위한 볼 엔드밀의 이송 속도 결정법을 제시하고자 한다. 먼저, 자유 곡면의 가공에서 발생될 수 있는 공구의 처짐에 따른 가공오차에 대하여 볼 엔드밀 공구의 처 짐벡터와 공작물의 공구 접촉점에서의 법선벡터로 표현되는 가공오차(machining error ) 예측 모델식을 유도하였다. 본 가공오차 예측 모델식은 다시 절삭날당 가지는 이 송량의 함수로 전개되어 그 곡면의 주어진 가공 공차(machining tolerance)를 만족시 키는 이송속도를 결정하게 된다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.34-38
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• 1992

Geometry based CAD/CAM system is hard to achieve "net shape machining" For a net shape machining, the machining errors should be compensated by off-line CAD/CAM system followed by on-line control system. In this paper, we investigate an off-line compensation scheme for the machining errors due to tool deflection in contouring operation. The significance of the deflection errors is first shown, and a compensation is sought via modifying the nominal tool path. In modification, tool deflection amount is iteratively compensated until the deflection amount is iteratively compensated until the deflected path results in the desired contour within a tolerance. The path modification algorithm has been tested via computer simulation. The developed algorithm can be used as a postprocessor for the current CAD/CAM system based on geometric modeling as a means for enhancing the machining accuracy.