• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.399-406
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• 2001

This study describes the geometric characteristic and the 5-axis machining method of end mill body with insert tip. The geometry of end mill body is consisted of the flute part and the insert tip part. Thus, this study defines the flute part as ruled surface with constant helix angle and the insert tip part as rectangular plane on general direction. The geometric algorithm and the 5-axis NC part program were calculated by our programmed software and a sampled end mill body was machined on 5-axis machining center equipped with two index tables. The machined end mill body with insert tip was very agreeable to the designed end mill body with insert tip. Thus, the method proposed in this study may be very useful for the machining of end mill body with insert tip.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.7 s.196
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• pp.60-68
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• 2007

This paper presents an efficient 5-axis roughing method for centrifugal impeller. The efficient roughing is minimization of cutting time through minimizing tool tilting and rotating motions. To minimized cutting time, machining area is divided into sub-cutting regions using control points on hub curves and shroud curves of blade used to design and analyze centrifugal impeller. For sub-cutting regions, diameters of cutting tools are determined as big as possible. Then, tool paths are generated with the tilting axis and rotating axis of 5-axis machine limited and fixed, which can give more efficient machining speed and machining stability than the conventional methods. Experimental results show that the proposed method is more efficient than the conventional methods to mill with the only one cutting tool without dividing area and the previous methods to mill with simultaneous 5-axis processing with dividing area.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.1
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• pp.38-48
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• 2007

In this paper, we propose an image-based method for modeling 3D objects with curved surfaces based on the NURBS (Non-Uniform Rational B-Splines) representation. Starting from a few calibrated images, the user specifies the corresponding curves by means of an interactive user interface. Then, the 3D curves are reconstructed using stereo reconstruction. In order to fit the curves easily using the interactive user interface, NURBS curves and surfaces are employed. The proposed surface modeling techniques include surface building methods such as bilinear surfaces, ruled surfaces, generalized cylinders, and surfaces of revolution. In addition to these methods, we also propose various advanced surface modeling techniques, including skinned surfaces, swept surfaces, and boundary patches. Based on these surface modeling techniques, it is possible to build various types of 3D shape models with textured curved surfaces without much effort. Also, it is possible to reconstruct more realistic surfaces by using proposed view-dependent texture acquisition algorithm. Constructed 3D shape model with curves and curved surfaces can be exported in VRML format, making it possible to be used in different 3D graphics softwares.

• Journal of computational fluids engineering
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• v.18 no.4
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• pp.1-8
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• 2013

The performance of small-size impellers with ruled surfaces was investigated for flank milling over a wide speed range, using computational fluid dynamics analyses and gas bench tests. An impeller with a ruled surface was designed, manufactured, and tested to evaluate the effects of blade loading, the backsweep angle, and the relative velocity distribution on the compressor performance. The simulations and tests were completed using the same compressor cover with identical inlet and outlet channels to accurately compare the performance of the abovementioned impeller with a commercial impeller containing sculptured blades. Both impellers have the same number of blades, number of splitters, and shroud meridional profiles. The backsweep angles of the blades on the ruled impeller were selected to work with the same pinched diffuser as for a sculptured impeller. The inlet-to-exit relative velocity diffusion ratio and the blade loading were provided to maximize the flow rate and to minimize the surge flow rate. The design flow rate, rpm, were selected same for both impellers. Test results showed that for the compressor stage with a ruled impeller, the efficiency was increased by 0.32% with an extended surge margin without a reduction in the pressure ratio as compared to the impeller with the sculptured design. It was concluded that an increased relative velocity diffusion coupled with a large backsweep angle was an effective way to improve the compressor stage efficiency. Additionally, an appropriate blade loading distribution was important for achieving a wide operating range and higher efficiency.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.399-404
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• 2002

An efficient method of machining impeller is presented. In the roughing process, the cutting area is divided into two regions to reduce cutting time and select cutting tools. The regions are determined by characteristic point on the geometry of impeller blade. Then, the tool of the maximum radius is selected in each area. Tool interference in cutting areas is avoided by checking the intersection between cooing tool axis and ruling line on blade surface.

• Communications of the Korean Mathematical Society
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• v.15 no.3
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• pp.533-540
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• 2000

In the present paper, we study a non-degenrate ruled surface along a null curve in a 3-dimensional Minkowski space E31, which is called a null scroll, an investigate some characterizations of null scrolls satisfying the condition H=AH, A Mat(3, ), where denotes the Laplacian of the surface with respect to the induced metric, H the mean curvature vector and Mat(3, ) the set of 3$\times$3-real matrices.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1814-1821
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• 2002

NC cutting simulation is an important factor in the development of products. The geometric modelling of cutter swept surface should be done in NC cutting simulation. A part of cutter swept surface is a ruled surface blended with silhouette curve and cutter path. Finding an intersection point between cutter swept surface and a line is one of major problems in Z-map based cutting simulation. In this paper, cutter swept surface is defined parametrically and it's intersection point with Z-map is found in an exact form. Triangular grid Z-map based 3-axis NC cutting simulation is performed.

• Communications of the Korean Mathematical Society
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• v.39 no.3
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• pp.757-774
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• 2024

In three dimensional Euclidean space we consider kinematical invariants of the surface which is generated by the motion of a planar curve, especially, the surface which is foliated by circles. At first we characterize the properties of single parameter plane with the theories of unit spherical curve in three dimensional Euclidean space. Then using these results we give the invariants and differential invariants, kinematical properties and some special examples of the surface foliated by circles. The methods established here can be used to the other kinds of the surface in three dimensional Euclidean space.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1795-1798
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• 2003

This paper presents a method for impeller modeling by the reverse engineering and the 5-axis machining. The impeller is composed of pressure surface, suction surface and leading edge, and so on. The impeller is modeled by using the characteristic curves of impeller such as hub curves, shroud curves and leading edge. The characteristic curves are extracted from the scanned data. The hub curves and shroud curves are generated by intersection between blade surface and hub boundary and shroud boundary. respectively. A sample impeller machining is performed by tool path plan and post-processing with inverse kinematic solution.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.839-845
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• 2007

In this paper, a polishing pad has been analyzed in detail, to understand surface phenomena of polishing process. The polishing pad plays a key role in polishing process and is one of the important layer in polishing process, because it is a reaction layer of polishing[1]. Pad surface physical property is also ruled by pad profile. The profile and roughness of pad is controlled by different types of conditioning tool. Conditioning tool add mechanical force to pad, and make some roughness and profile. Formed pad surface will affect on polishing performance such as RR (Removal Rate) and uniformity in CMP Pad surface condition is changed by conditioning tool and dummy run and is stable at final. And this research, we want to reduce break-in and dummy polishing process by analysis of pad surface and artificial machining to make stable pad surface. The surface treatment or machining enables to control the surface of polishing pad. Therefore, this research intends to verify the effect of the buffing process on pad surface through analysis of the removal rate, friction force and temperature. In this research, urethane polishing pad which is named IC pad(Nitta-Haas Inc.) and has micro pore structure, is studied because, this type of pad is most conventional type.