• 한국공작기계학회논문집
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• 제14권2호
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• pp.83-90
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• 2005

A mirror cam mechanism a kind of conjugate cam mechanism consists of two cams, two rollers, and two links. Since profiles of two mirror cam are identical, a simultaneous machining of two cams is achievable. Some machining errors on cam profiles do not result in the internal acting force, which often causes problems in high speed cam mechanism between two links. Also, since angular accelerations of two links are same, the internal acting force by the difference of the angular accelerations does not occur in the mechanism. Thus the mirror cam mechanism is very useful in high speed machinery. This paper studies a design method as well as a machining method, and develops an exclusive CAD/CAM software for mirror cam profiles. The developed CAD/CAM software is applied to a typical mirror cam mechanism and a mock-up equipment is built in order to test the machinism mirror cm. Experimental investigations show that the contact between cam surface and roller surface according to cam rotation agrees well with the simulation on the developed CAD/CAM software.

• 한국레이저가공학회지
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• 제17권3호
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• pp.15-18
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• 2014

In this paper, we studied a machining method using a diffractive beam splitter (DBS) and multi- pulse repeated radiation for breathable film. We fabricated micro-grooves on polypropylene (PP) films using multi-pulse radiation and one-shot radiation (radiating pulses at once) and a DBS. In the result, width and depth of the PP film using multi-pulse repeated radiation were more precisely controllable. Therefore, this method can be applicable to in manufacturing breathable film precisely at a high speed.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.83-88
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• 2003

In this study, experiments were conducted with an ultra-precision machine, developed In domestic, to find the characteristics and the most suitable cutting conditions of ultra-precision machining. To maximize the performance of the machine, the machine was installed in a room that is protected from vibration and is maintained constant temperature and constant humidity. Selected work pieces are an aluminum-alloyed material, which has excellent corrosion resistance and has low deformation. The used tool is synthetic poly crystal diamond which has excellent abrasion resistance and has low affinity. Four types of tool nose radius were used such as 0, 0.1, 0.2 and 0.4mm. Machining is performed with cutting speed of 500, 800 and 1000m/min., feed rate of 0.005, 0.008, 0.010mm/rev. and cutting depth of 0.0005, 0.0025 and 0.005mm respectively which can generally be used in the field as a cutting condition. As a method of evaluation surface roughness was measured for each cutting condition and reciprocal characteristics are computed for each tool nose radius, cutting speed, feed rate and cutting depth. As a result the most suitable cutting condition and characteristics of ultra-precision machining were identified which can usefully be applied in the industrial field.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.504-509
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• 2003

In this paper, a multi-step optimization using a G.A.(Genetic Algorithm) with variable penalty function is introduced to the structural design optimization of a high speed machining center. The design problem, in this case, is to find out the best cross-section shapes and dimensions of structural members which minimize the static compliance, the dynamic compliance, and the weight of the machine structure simultaneously. The first step is the cross-section shape optimization, in which only the section members are selected to survive whose cross-section area have above a critical value. The second step is a static design optimization, in which the static compliance and the weight of the machine structure are minimized under some dimensional constraints and deflection limits. The third step is a dynamic design optimization, where the dynamic compliance and the structure weight are minimized under the same constraints as those of the second step. The proposed design optimization method was successful applied to the machining center structural design optimization. As a result, static and dynamic compliances were reduced to 16% and 53% respectively from the initial design, while the weight of the structure are also reduced slightly.

• 한국공작기계학회논문집
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• 제13권1호
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• pp.9-15
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• 2004

In this study, experiments were conducted with an ultra-precision machine, developed in domestic, to find the characteristics and the most suitable cutting conditions of ultra-precision machining. To maximize the performance of the machine, the machine was installed in a room that is protected from vibration and is maintained constant temperature and constant humidity. Selected work pieces are an aluminum-alloyed material, which has excellent corrosion resistance and has low deformation. The used tool is synthetic poly crystal diamond, which has excellent abrasion resistance and has low affinity. Four types of tool nose radius were used such as 0, 0.1, 0.2 and 0.4mm. Machining is performed with cutting speed of 500, 800 and 1000m/min., feed rate of 0.005, 0.008, 0.010mm/rev. and cutting depth of 0.0005, 0.0025 and 0.005mm respectively which can generally be used in the field as a cutting condition. As a method of evaluation, surface roughness was measured for each cutting condition, and reciprocal characteristics are computed for each tool nose radius, cutting speed, feed rate and cutting depth. As a result, the most suitable cutting condition and characteristics of ultra-precision machining were identified which can usefully be applied in the industrial field.

• 한국기계가공학회지
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• 제11권2호
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• pp.27-33
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• 2012

A marine propeller is designed for preventing cavitation priority. Cavitation is a phenomenon which is defined as the vibration or noise by dropping the pressure on the high-speed rotation of the propeller. There has to be a enough thrust on the low-speed rotation for preventing cavitation. Thus, it has to be considered in the increasing of the number of blade and the angle of wing to design the propeller. In addition, flow resistance will be increasing by narrowing the width between blades. So high quality surface roughness of the hub to minimize flow resistance is required. Interference problems with tool and neighboring surfaces often take place from this kind of characteristics of the propeller. During 5-Axis machining of these propellers, the excessive local interference avoidance, necessary to avoid interference, leads to inconsistency of cutter posture, low quality of machined surface. Therefore, in order to increase the surface quality, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. This study, by using a MC-space algorithm for interference avoidance and a MB-spline algorithm for continuous control, is intended to create a 5-Axis machining tool path with excellent surface quality. Also, an effectiveness is confirmed through a verification manufacturing.

• 한국기계가공학회지
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• 제11권6호
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• pp.48-54
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• 2012

In recent years, developments in the semiconductor and electronic industries have brought a rapid increase in the use of large size silicon. However, for many companies, it is hard to produce 400mm or 450mm wafers, because of excesive funds for exchange the equipments. Therefore, it is necessary to investigate 300mm wafer to obtain a better efficiency and a good property rate. Polishing is one of the important methods in manufacturing of Si wafers and in thinning of completed device wafers. This research investigated the surface characteristics that apply variable machining conditions and Taguchi Method was used to obtain more flexible and optimal condition. In this study, the machining conditions have head speed, oscillation speed and polishing time. By using optimum condition, it achieves a ultra precision mirror like surface.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 Handout for 2000 Inter. Machine Tool Technical Seminar
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• pp.19-27
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• 2000

High speed machining (HSM), specifically end milling and ball end cutting, is attracting interest in the die/mold or aerospace industries for the machining of complex 3D surfaces. HSM of difficult-to-cut materials such as die/mold steels, titanium alloys or nickel based superalloys generates the concentrated thermal/frictional damage at the cutting edge of the tool and rapidly decreases the tool life. Following a brief introduction on HSM and reated aerospace or die/mold work, the paper reviews published data on the effect of cutter/workpiece orientation and cutting environments on tool performance. First, experimental work is detailed on the effect of cutter orientation on tool life, cutting forces, chip formation, specific force and workpiece surface roughness. Cutting was performed using 8 mm diameter PVD coated solid carbide cutters with the workpiece mounted at an angle of 45 degree from the cutter axis. A horizontal downwards cutting orientation proveded the best tool life with cut lengths ∼50% longer than for all other directions (horizontal upwards, vertical downwards, vertical upwards). Second, the cutting environments were investigated for dry, flood coolant, and compressed chilly air coolant cutting. The experiments were performed for various hardened materials and various coated tools. The results show that the cutting environment using compressed cilly air coolant provided better tool life than the flood coolant or the dry.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.89-94
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• 2003

Hard coatings are known to improve the performance of cutting tools in aggressive machining applications, such as high speed machining. New superhard Ti-Al-Si-W films, characterized by a nanocomposite nano-sized (Ti,Al,Si)N crystallites embedded in amorphous $Si_3 N_4$ matrix, could be successfully synthesized on WC-Co substrates by a hybrid coating system of arc ion plating(AIP) and sputtering method. The hardness of Ti-Al-Si-N film increased with incorporation of Si, and had the maximum value ~50 GPa at the Si content of 9 at.%, respectively. And the X-ray diffraction patterns of Ti-Al-Si-N films with various Si content is investigated. In this study, Ti-Al-Si-N coatings were applied to end-mill tools made of WC-Co material by a hybrid coating system. Cutting tests fir the high-hardened material (STD11,$H_R$)C62 and their performances in high speed cutting conditions were studied. Also, the tool wear and tool lift of Ti-Al-Si-N with various si(6, 9, 19) contents were measured.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.605-606
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• 2006

Today, the need for more flexible and adaptive production system and integrated management of their manufacturing information and facilities is ever increasing to cope with competitive and ever-changing global market environments and complexity of new control systems. This paper presents the whole system architecture and the technological characteristics of for each individual system layer which are able to flexibly integrate and manage high-speed and high-precision machining systems. It is investigated that monitoring and integrated management of the control systems can be realized with consideration of detailed information of various CNCs, and the management function may be easily constructed and extended using components of the manufacturing execution layer.