• Korean Journal of Computational Design and Engineering
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• v.10 no.6
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• pp.455-464
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• 2005

This paper discusses the methods of computing tool-paths for machining free-form surfaces on 3-axis CNC machines in die and mould making. In computational view this paper describes the characteristics and issues of the geometric information and the shape, which make computing tool-paths difficult. Important points that should be considered in devising a computing method are also discussed. A newly implemented method is explained and compared with an old method for a commercial CAM system. The implemented method is used in a commercial CAM system and the computing time for an example is presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.417-422
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• 1993

In order to minimize turnaround of machining in FMS lines, CAD/CAM/CAT integrated system called MascCAM was developed. Developing enhanced CAM and inspection modules in the MascCAM environment, 2D came, 2 $^{1}$2/ D prismatic parts and 3D free-formed surfaces were able to be automatically designed, manufactured and inspected on the machine tools by using AutoCAM and Z-map. Introducing Z-map technique, the MascCAM was able to be interfaceed with and CAD system. Developed QPPGT module generates a quick and fool-proof inspection work to users. A vertical and a horizontal machining center equipped with FANUC OMC were used for experiments. Performance of the system was confirmed by a large amount of experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.251-254
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• 2000

In this paper, we developed an automated program for the modeling and manufacturing of three-dimensional roller gear cams. A computer program employing the theory of gearing and coordinate transformation is developed for synthesizing and animating cam mechanisms. A method using wire frame modeling and shading by triangular element is presented, and effectively used for modeling of example with reduced computation time. Then a module for generation NC program for a five-axis CMC machine to manufacture roller gear cam is established.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.380-384
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• 1993

In precision wire electrode discharge machining by CAD/CAM, it is the most important problem on machining method to determine the wire electrode offset amout from the accurate calculation of discharge gap in order to increase the machining accuracy, after fixing the main machining conditions such as machining speed, wire tension, coolant conductivity, gap vlotage. The present study shows the relationships between discharge gap and main machining conditions by means of a series of experiment concerned with the gap using the workpiece of STD 11, and suggests the experimental eguation to calculate the accurate wire electrode offset amount under the given machining conditions for spot workers.

• International Journal of CAD/CAM
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• v.2 no.1
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• pp.23-28
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• 2002

This paper presents an efficient line-offset algorithm for general polygonal shapes with islands. A developed sweep-line algorithm (SL) is introduced to find all self-intersection points accurately and quickly. The previous work is limited to handle polygons that having no line-segments in parallel to sweep-line directions. The proposed algorithm has been implemented in Visual C++ and applied to offset point sequence curves, which contain several islands.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.161-167
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• 1993

This paper deals with a new method for the machining of a die cavity defined by sculptured surfaces. In machining die cavities or pockets, process planners have been faced with some troulbes. One of the troubles ius to rebove a great deal of material within a given boundary while avoiding cutter interference. Cutter interference is a ciritical problem in NC machining of a die cavity. Even though this cavity machining has been implemented in many CAM systems, most of them can handle limited shapes of cavities or pockets. In this paper, a procedure has been developed to machine die cavity or pocket of a sculptured surface. The offset surfaces of the part surfaces and boundary surfaces are determined to calculate the intersection curves. These intersection curves form a FACE on the part surface, and the interference free tool pathe is generated by eliminating the points outside the FACE when computing the cutter contact (CC) data. Additionally, the cutter location (CL) data obtained from the CC data convert to an NC data. The NC data generated through this algorithm are verified on the CINCINNATI milling machine. A propotype die cavity machining system has been implemented in FORTRAN language and FIGARO graphics library on IRIS workstation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1179-1184
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• 2003

The technique for measuring the rotational speed of tappet in direct acting type valve train system has been developed. The optic signal monitoring system with laser and optic fiber was designed to follow the signal of tappet rotation. The system was based on ON/OFF signal generation from the additional encoder teeth under the tappet with optic fibers attached photo transistor. The data showed that tappet rotation was affected by offset, oil temperature and cam shaft operating speed. Also it was found that tappet rotation increases with oil temperature. Tappet spin was delayed 10∼s20$^{\circ}$ cam angle after valve opening. The instantaneous rotational speed of tappet was reciprocal to cam shaft speed and the tappet and the cam angle ratio was located in the range of 0.1∼0.3.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.122-129
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• 2005

Shoe with leather upper such as safety and golf shoe requires a roughing process where the upper is roughed fur helping outsole to be cemented well. It is an important and basic process for production of leather shoe but is not automated yet. Thus, there are problems that the defect rate is high and the quality of roughed surface is not uniform. In order to solve such problems, the interest in automation of roughing process is being increased and this paper introduces CAM system for 5-axis automatic roughing machine as one part of automation of roughing process. The CAM system developed interpolates a B-spline curve using points measured from the Roughing Path Measurement System. The B-spline curve is used to generate the tool path and orientation data fer a roughing tool which has not only stiffness but also flexibility to rough the inclined surface efficiently. For productivity, the upper of shoe is machined by side of the roughing tool and tool offset is applied to the roughing tool for machining of inclined surface. The generated NC code was applied to 5-axis polishing machine for the test. The upper of shoe was roughed well along the roughing path data from CAM and the roughed surface was proper fur cementing of the outsole.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.3
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• pp.123-137
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• 1993

In this paper, an integrated approach is proposed to generate gouging-free Cartesian tool paths for machining sculptured surfaces from 3D measurement data. The integrated CAD/CAM system consists of two modules : offset surface module an Carteian tool path module. The offset surface module generates an offset surface of an object from its 3D measurement data, using an offsetting method and a surface fitting method. The offsetting is based on the idea that the envelope of an inversed tool generates an offset surface without self-intersection as the center of the inversed tool moves along on the surface of an object. The surface-fitting is the process of constructing a compact representation to model the surface of an object based on a fairly large number of data points. The resulting offset surtace is a composite Bezier surface without self-intersection. When an appropriate tool-approach direction is selected, the tool path module generates the Cartesian tool paths while the deviation of the tool paths from the surface stays within the user-specified tolerance. The tool path module is a two-step process. The first step adaptively subdivides the offset surface into subpatches until the thickness of each subpatch is small enough to satisfy the user-defined tolerance. The second step generates the Cartesian tool paths by calculating the intersection of the slicing planes and the adaptively subdivided subpatches. This tool path generation approach generates the gouging-free Cartesian CL tool paths, and optimizes the cutter movements by minimizing the number of interpolated points.

• Journal of Technologic Dentistry
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• v.41 no.2
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• pp.81-86
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• 2019

Purpose: The purpose of the present study was to compare the internal fit of two different temporary restorations fabricated by dental CAD/CAM system and to evaluate clinical effectiveness. Methods: Composite resin tooth of the maxillary first molar was prepared as occlusal reduction(2.0mm), axial reduction(1mm offset), vertical angle(6 degree) and chamfer margin for a temporary crown and duplicated epoxy die was fabricated. The epoxy dies were used to fabricate provisional restorations by CAD/CAM milling technique or 3D-printing technique. The inner data from all crowns were superimposed on the master die file in the 'best-fit alignment' method using 3D analysis software. Statistical analysis was performed using a Wilcoxon's rank sum test for differences between groups. Results: It showed that the internal RMS(Root Mean Square) values of the additive group were significantly larger than those of other group. No significant differences in internal discrepancies were observed in the temporary crowns among the 2 groups with different manufacturing method. Conclusion: All the groups had the internal fit within the clinical acceptable range (< $50{\mu}m$). The continuous research in the future to be applied clinically for the adaptation of additive manufacturing technique are needed.