• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.683-688
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• 1994

Recently, the Z-Map model has been used widely to represent the three dimensional geometric shape and to achieve the cross-section and point evaluation of the shape. In this paper, the CNC cutting planning and simulation modules for product with three dimensional geometric shape are realized based on the Z-Map model. The realized system has the various capabilities related to the automatic generation of tool path for the rough and finish cutting processes, the automatic elimination of overcut, the automatic generation of CNC program for a machining center and the cutting simulation. Especially, the overcut-free tool path is obtained by using the CL Z-Map models which are composed of the offset surfaces of the geometric shape of product.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.180-188
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• 1998

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]. While z-map is the simplest form of representing sculptured surfaces and it is the most versatile scheme for modeling nonparametric objects, its practical application in industry (eg, tool-path generation) aroused much controversy over its weaknesses ; accuracy, singularity (eg, vertical wall), and some excessive storage needs. Although z-map has such limitations, much research on the application of z-map can be found in various articles. However, research on the systematic analysis of sculptured surface shape representation via z-map model is rather rare. Presented in this paper are the following: shape modeling power of the simple z-map model, exact (within tolerance) B-map representation of sculptured surfaces which have some feature-shapes such as vertical-walls and real sharp-edges by adopting some complementary B-map models, and some application examples.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.5
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• pp.38-45
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• 1998

The Z-map model which is quite similar to the non-parametric patch is widely used to describe the shape of a surface because of its simplicity. Despite the inherent advantage of z-map model. it has drawbacks that there exists difficulty in expressing the vertical walls and its related contact treatment method. In the region of vertical walls, there is a convergence problem in searching the contact point. In this study a contact point finding scheme is presented, based on the z value of the z-map model on the sheet normal direction. To show the utility of this scheme a compared with the experimental results. The effects of the Z-map grid distances and the interpolations of the inside Z-map value are also discussed.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.1
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• pp.49-56
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• 2002

The Z-map is a special farm of discrete non-parametric representation in which the height values at grid points on the xy-plane are stored as a 2D array z[ij]. While the z-map is the simplest farm of representing sculptured surfaces and is the most versatile scheme for modeling non-parametric objects, its practical application in industry (eg, tool-path generation) has aroused much controversy over its weaknesses, namely its inaccuracy, singularity (eg, vertical wall), and some excessive storage needs. Much research or the application of the z-map can be found in various articles, however, research on the systematic analysis of sculptured surface shape representation via the z-map model is rather rare. Presented in this paper are the following: shape modeling power of the simple z-map model, exact (within tolerance) z-map representation of sculptured surfaces which have some feature-shapes such as vertical-walls and real sharp-edges by adopting some complementary z-map models, and some application examples.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.551-554
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• 2002

The paper discusses new approach for machining operation simulation using enhanced Z map algorithm. To extract the required geometric information from NC code, suggested algorithm uses supersampling method to enhance the efficiency of a simulation process. By executing redundant Boolean operations in a grid cell and averaging down calculated data, presented algorithm can accurately represent material removal volume though tool swept volume is negligibly small. Supersampling method is the most common form of antialiasing and usually used with polygon mesh rendering in computer graphics. The key advantage of enhanced Z map model is that the data structure is same with conventional Z map model, though it can acquire higher accuracy and reliability with same or lower computation time. By simulating machining operation efficiently, this system can be used to improve the reliability and efficiency of NC machining process as well as the quality of the final product.

• Korean Journal of Computational Design and Engineering
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• v.4 no.4
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• pp.355-359
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• 1999

This paper presents a method for determining machining parameters in electrical discharge machining process (EDM) based on discharge area. The parameters are the peak value of currents, the pulse-on time, and the pulse-off time, on which the EDM performance depends chiefly. The optimal machining parameters are closely related on discharge area, which can be calculated from a tool electrode and a discharge height. In the paper the discharge area is obtained from NC code for machining the tool electrode instead of its geometric model. The method consists of following three steps. First a Z-Map model is constructed from the NC code. Secondly, the discharge area is obtained from the Z-Map model and a Z-height. Finally, the machining parameters are calculated from the discharge area. An introduced example shows that the machining parameters are calculated by the using a Z-map model obtained from the machining data for a tool electrode.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.115-121
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• 1996

Recently, the Z-Map model has been used widely to represent the three dimensional geometric shape and to achieve the cross-section and point evaluation of the shape. In this paper, the CNC cutting planning and simulation modules for product with three dimensional geometric shape are realized based on the Z-Map model. The realized system has the various capabilities related to the automatic generation of tool path for the rough and finish cutting processes, the automatic elimination of overcut, the automatic generation of CNC program for a machining center and the cutting simulation. Especially, the overcut-free tool path is obtained by using the CL Z-Map models which are composed of the offset surfaces of the geometric shape of product.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.86-89
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• 2002

In NC machining, the ability to automatically generate an optimal process plan is an essential step toward achieving automation, higher productivity, and better accuracy. For this ability, a system that is capable of simulating the actual machining process has to be designed. In this paper, a milling process simulation system for the general NC machining was presented. The system needs first to accurately compute the cutting configuration. ME Z-map(Moving Edge node Z-map) was developed to reduce the entry/exit angle calculation error in cutting force prediction. It was shorn to drastically improve the conventional Z-map model. Experimental results applied to the pocket machining show the accuracy of the milling process simulation system.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.824-828
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• 2000

Prior to the downloading of the NC codes to a machining center, the NC tool-path can be verified in a computer. The Z-map is one of the tools for the verification of NC tool-path. The Z-map is a two dimensional array in which the height values of the Z-axis direction vectors are stored. The Z-axis direction vectors are arranged in a rectangular grid pattern on the XY plane. The accuracy of the simulation comes from the grid interval. In the rectangular Z-map, the distances between the grid points are different. The distance in diagonal direction is larger than those in X or Y axis directions. For the rendering of the Z-map, a rectangular grid is divided into two triangular facets. Depending on the selection of a diagonal, there are two different cases. In this paper, triangular Z-map, in which the Z-axis direction vectors are arranged in a triangular grid pattern on XY plane, is proposed. In the triangular Z-map, the distances between grid points are equal. There is no ambiguity to make triangular facets for the rendering.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.725-729
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• 2000

This paper presented a new model of NC verification in ball end milling. The model verifies the over cut the under cut and the surface roughness using NC file generated from CAM and cutting condition. The model uses Z-map model to verify workpiece. In this paper, the model used the velocities of x, y and z direction and obtained a center point of a ball end mill for modeling Z-map of workpiece. To investigate the performance of the model simulation study was carried out. As the results, the model gave geometry accuracy of workpiece, the surface roughness and the chip loads in finish cutting that can predict tool chipping.