• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1888-1896
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• 2002

This study presents a new type of CNC interpolator that is capable of generating cutter paths for ball-end milling of NURBS surfaces. The proposed surface interpolator comprises real-time algorithms for cutter contact (CC) path scheduling and CC path interpolator. Especially in this study, a new interpolator module to regulate cutting forces is developed. This propose algorithm utilizes variable-feedrate commands along the CC path according to the curvature of machined surfaces during the interpolation process. Additionally, it proposes an OpenGL graphic library for computer graphics and animation of interpolated tool-position display. The proposed interpolator is evaluated and compared with the existing method based on constant feedrates through computer simulations.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.389-392
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• 2000

Gouge-free tool-path generation is an important issue in mold & die machining and researches on cutter interference avoidance can be found in many articles. One of the various methods is construction of tool-offlet surface or cutter-location (CL) surface on which the cutter-center point (CL-point) locates. Provided that the CL surface is represented in a suitable form, cutter-interference avoidance can be performed without the burden of computing CL data for every cutter-contact (CC) point. In the paper, various methods of constructing a CL surface in the z-map form are presented, where z-map is a special form of discrete nonparametric representation in which the height values at grid points on the xy-plane are stored as a 2D array z［i,j］.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.4
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• pp.325-335
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• 2000

Gouge-free tool-path generation is an important issue in mold & die machining and researches on cutter interference avoidance can be found in many articles. One of the various methods is construction of tool-offset surface of cutter-location (CL) surface on which the cutter-center point (CL-point) locates. Provided that the CL surface is represented in a suitable form, cutter-interference avoidance can be performed without the burden of computing CL data for every cutter-contact (CC) point. In the paper, various methods of constructing a CL surface in the z-map form are presented, where z-map is a special form of discrete nonparametric representation in which the height values at grid points on the xy-plane are stored as a 2D array z[i,j].

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.371-374
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• 1997

This study presents a new type of real-t~me CNC interpolator that is capable of generating cutter paths for ball-end milling of NURBS surfaces. The proposed surface interpolator comprises real-time algorithms for cutter-contact (CC) path scheduling and CC path interpolation. Especially, in this study, a new interpolator module to regulate cutting forces is developed. This proposed algorithm utilizes variable-feedrate commands according to the curvature of machined surfaces. The proposed interpolator is evaluated and compared with the conventional method based on constant feedrates through computer simulation.

• Korean Journal of Computational Design and Engineering
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• v.7 no.1
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• pp.34-41
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• 2002

Five-axis NC machining, in general, is utilized in fabricating impellers, turbine blades, marine propellers that can be machined more effectively rather than three-axis machining. There have been many researches concerning tool interference avoidance, optimization of tool orientation. The C-space or Configuration-space was originated from the robotics area, which depicts interference-free joint-values in motion planning. In the paper we propose an optimizing scheme by which the maximum effective-radius of a face-milling cutter can be achieved for each CC(cutter-contact) point. Also the concept of a C-space for a CC point, the effective-radius map for 5-axis face-milling, and some illustrative examples of marine propeller machining, are presented.

• Korean Journal of Computational Design and Engineering
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• v.9 no.1
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• pp.35-43
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• 2004

It is well known that the five-axis machining has advantages of tool accessibility and machined surface quality when compared with conventional three-axis machining. Traditional researches on the five-axis tool-path generation have addressed interferences such as cutter gouging, collision, machine kinematics and optimization of a CL(cutter location) or a cutter position. In the paper it is presented that optimal CL data for a face-milling cutter moving on a tool-path are obtained by incorporating TSS(tool swept surface) model. The TSS model from current CL position to the next CL position is constructed based on machine kinematics as well as cutter geometry, with which the deviation from the design surface can be computed. Then the next CC(cutter-contact) point should be adjusted such that the deviation conforms to given machining tolerance value. The proposed algorithm was implemented and applied to a marine propeller machining, which proved effective from a quantitative point of view. In addition, the algorithm using the TSS can also be applied to avoid cutter convex interferences in general three-axis NC machining.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.161-167
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• 1996

In five-axis milling, optimal CL-data (cutter location data) should be generated to have advantages over three-axis milling in terms of accuracy and efficiency. This paper presents an algorithm for generating collision-free CL-data for five-axis milling using potential energy method. By virtually charging the cutter and part surfaces with static electricity, global collision as wells as local interference is eliminated. Additionally, machining efficiency is improved by minimizing the curvature difference between the part surface and tool swept surface at a CC-point (cutter contact point) simultaneously.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.3
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• pp.158-164
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• 1996

In this paper, the CNC cutting planning module for product with three dimensional solid shape is realized to develop a smart CAD/CAM system which performs systematically from the shape design of procuct by the B-Rep solid modeler to the CNC cutting of product by a machining center. The three dimensional solid shape of product can be easily designed and constructed by the Euler operators and Boolean operators of the solid modeler. And the various functions such as the automatic generation of tool path for the rough and finish cutting processes, the automatic elimination of overcut, the automatic generation of CNC code for the machining center and do on, are established. Especially, the overcut-free tool paths are obtained by splitting the CL solid which is composed of the offset surfaces of the solid shape of product.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1320-1323
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• 1996

This paper describes an interpolation method for a parametric surface. A parametric surface is approximated to triangular mesh surfaces and then the basic paths are achieved. As the generated path is a series of linear segments, this algorithm can be easily adapted to general NC controllers. The generated paths have minimal transfer length and are gouge-free within the approximation tolerance. The problems, induced when the paths are represented by linear segments, are overcome without making any path deviation by this algorithm. This algorithm saves machining time by eliminating overdetermined tool paths and keeping the desired average feedrate, which improve productivity and lead to lower production costs.