• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.55-64
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• 2001

In this study, hemisphere and cylindrical shapes were machined for different tool paths and machining conditions with ball endmill cutters. Tool deflection, cutting forces and shape accuracy were measured according to the inclination position of the sculptured surface. As the decreasing of inclination position angle, the tool deflection was increased due to the decreased cutting speed when the cutting edge is approaching toward the center. Tool deflection when upward cutting is obtained less than that of downward cutting and down-milling in upward cutting showed the least tool deflection for the sculptured surface. Roundness values were found in least roundness error when down-milling in upward cutting. It is obtained the very little difference between 90。and 45。 of inclination position angle. The best surface roughness value was obtained in upward up-milling and showed different tendency with tool deflection and cutting force. For down-milling, the cutting resistance of the side wall direction is larger than that of feed direction. Therefore, this phenomenon which is received over cutting resistance can be caused of chatter.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.145-153
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• 1995

An algorithm for the automatic generation of quadrilateral shell elements on three-dimensional sculptured surfaces has been developed, which is one of the key issues in the finite element analysis of structures with complex shapes such as automobile structures. Mesh generation on sculptured surfaces is performed in three steps. First a sculptured surface is transformed to a projection plane, on which the loops are subdivided into subloops by using the best split lines, and with the use of 6-node/8-node loop operators and a layer operator, quadrilateral finite elements are constructed on this plane. Finally, the constructed mesh is transformed back to the original sculptured surfaces. The proposed mesh generation scheme is suited for the generation of non-uniform meshes so that it can be effectively used when the desired mesh density is available. Sample meshes are presented to demonstrate the versatility of the algorithm.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.209-214
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• 2003

This study presents the analysis of ball end milling machinability and its application to the determination of the optimum feedrate in the CNC machining process of sculptured surface. The methods which estimate the cutting force system is approached experimentally. The estimation strategy, named technological processor, was applied to the machining process of sculptured surface for finding optimum variable feedrate. From the result of practical implementation for the test model, it is ascertain that the technological processor have brought the dispersion of force profiles. As compared with conventional imposing of cutting conditions, the machining time has reduced by more than 60%.

• 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.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.5 no.3
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• pp.66-72
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• 1996

The applicability of a new method, termed the whirling motion concept, for the improvement of the surface finish in milling three-dimensional sculptured surfaces has been investigated. A method for implementing this concept o conventional NC machines that utilize a suitably configured attachment has been proposed. The tool path equation for the ball-end milling process, based on the surface-shaping system, has been obtained. Both results of the computer simulation and the experiment verified the proposed approach.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.108-115
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• 2002

In measuring step for reverse engineering of sculptured surfaces, computer vision system is used to simplify the complicated surface by boundary edge detection method that minimizes the measuring error. The measured data by Coordinate measuring machine is clouded data points of surfaces which is segmented surface using image process. In this research, the measured data is approximated as NURBS surfaces by new suggested algorithm. The position and number of control points, selection of parametric values and compensation of weight factors are proposed. Finally, surface model is simulated and improved resulting performance is obtained.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.100-106
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• 2021

This paper presents a study on the improvement of the machining quality of sculptured-surfaces of molds according to the shape and posture of the tool. In the existing 3-axis machining, the methods using the ball end-mill and radius end-mill were analyzed for various cutting patterns and compared with those of the 5-axis machining. It was observed that the 5-axis machining using a ball end-mill obtained the finest surface roughness, and for the 3-axis machining, the optimal results were obtained for the one-way machining using a radius end-mill.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.119-126
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• 2000

Recently, according to the various taste of consumers, the design of a product is changed variously and complicatedly. The complicated product is not usually constructed with one path but multi-path. By the way, in machining, higher precision and the reduction of leading and machining time is required. But, for the multi-patch sculptured surface, the amount of machining data becomes large. This means the increase of leading and machining time. In this study, the tool path generation method with reparameterization is proposed for multi-patch sculptured surface and variable step size using NURBS is used to satisfy the precision and to reduce leading and machining time.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.3
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• pp.8-15
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• 2005

A new measuring method for tool deflection has been developed when sculptured surface is processed in ball-end milling. Since the vibration due to cutting forces has low frequencies, an electromagnetic sensor is used for measuring the exact vibration displacement. The amplitude and direction of vibration displacement during the cutting process is presented as orbital plot. In this study, it assumes that the vibration displacement is proportional to the length of cutting chip. Therefore, tool deflection is calculated by summing up the vibration displacement of unit chip length for engaged chip length. In addition, computer programs has been developed to predict the deflection of tools when machining sculptured surface. This developed program predicts the tool deflection per block of NC data, so that it can easily identify the parts which have the possibility of machining errors.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.1
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• pp.96-105
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• 1992

A study on the construction of a CAD/CAM system operated by 16 Bit PC basic language, for machining sculptured surface of die, was carried out. The system consists of 2 steps i.e., process for geometric modelling by wire frame and process for machining data generation. Geometric modelling for sculptured surface is made by the point data fitting, parallel sweeping, normal sweeping and linear connection of cross section curve. Machining data are gained by cutter off-set of geometric model data and machining carried out by DNC. This system is to be proved enough for rough cutting by actual machining experiment. But, for becoming a high level system, another method of cutter off-set has to be regarded and system must be reconstructed by another program language.