研究者詳細 - 岡田　晃

論文 - 岡田　晃

分割表示 396 件中 261 - 280 件目／全件表示 >>

Optimization of Nozzle Flushing Method for Smooth Debris Exclusion in Wire EDM 査読

Takuya Fujimoto, Akira Okada, Yasuhiro Okamoto, Yoshiyuki Uno

Key Engineering Materials 516 73 - 78 2012年6月

Direct micro-joining of flexible printed circuit and metal electrode by pulsed Nd:YAG laser 査読

Mohd Idris Shah Ismail, Yasuhiro Okamoto, Akira Okada, Yoshiyuki Uno, Kentaro Ueoka

International Journal of Precision Engineering and Manufacturing 13 ( 3 ) 321 - 329 2012年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

Laser micro-welding has proven to be a very successful tool for micro-joining in the electrical and electronic industries, where the miniaturization, the high strength and the high heat resistance are constantly requested. Recently, a flexible printed circuit (FPC) is expected as a new connection technology between electrical conductors according to the improvements of reliability and controllability with the diversification of the design concept. In this technology, it is required to weld a several tens μm thickness of FPC and a several hundreds μm thickness of metal electrode. This material combination accompanies the difficulty to control the welding phenomenon due to the differences of thermal property and heat capacity. As a good alternative, laser micro-welding has advantages of non-contact tool, low heat distortion and consistent weld integrity. In this study, the overlap welding of thin copper circuit on a polyimide film and a thick brass electrode was experimentally and numerically investigated by using a pulsed Nd:YAG laser. In addition, the shearing stress of overlap welding was evaluated with and without the control of pulse waveform, which can provide a well-directed controlling of the heat input with high energy density. The results showed that a porosity was observed as the major weld defect in the welding process without a pulse control. However, the appropriate controlled laser pulse configuration of micro-welding could remove the weld defects in the molten zone, improve the weld penetration stability and increase the weld strength. The potential benefits of controlled pulse waveform were discussed for the direct laser micro-welding process. It is clarified that the direct laser micro-welding of a thin copper circuit on a polyimide film and a thick brass electrode could be successfully achieved by appropriate controlled pulse waveform and heat input. © KSPE and Springer 2012.

DOI： 10.1007/s12541-012-0041-3

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Investigation on Micro-machining Characteristics and Phenomenon of Semiconductor Materials by Harmonics of Nd:YAG Laser 査読

Takayuki Hirano, Yasuhiro Okamoto, Akira Okada, Yoshiyuki Uno, Tomokazu Sakagawa, Shin-ichi Nakashiba

PROCEEDINGS OF PRECISION ENGINEERING AND NANOTECHNOLOGY (ASPEN2011) 516 ( 516 ) 36 - + 2012年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：TRANS TECH PUBLICATIONS LTD

Precision micro-machining without crack and heat affected zones is required in order to use high-performance materials such as silicon and silicon carbide, and it is expected that the higher harmonics of the Nd:YAG laser can perform precision micro-machining due to its high photon energy. However, even by using the harmonics of the Nd:YAG laser, a heat affected zone is inevitable due to the plasma generation. In order to reduce the influence of plasma on the processing results, it is important to understand the generation mechanism of plasma. Therefore, the laser induced plasma in micro-drilling of silicon carbide was observed by a high-speed shutter camera, and the influence of laser wavelength and surrounding conditions on the machining characteristics were experimentally investigated. The removal depth increased with decreasing wavelength and the surrounding gas pressure. The surface integrity was improved by the combination of shorter wavelength and reduced pressure conditions. The behavior of laser induced plasma was different from the wavelength of the laser beam and the surrounding gas pressure. Under atmospheric pressure conditions, the plasma grew greatly and affected the wider surface around the drilled hole with increasing wavelength. Under reduced pressure conditions, there was little difference in plasma size by wavelength, and the affected zone around the drilled hole became relatively smaller. It became clear. that a low surrounding gas pressure and shorter wavelength were important to obtain better surface integrity and highly efficient processing.

DOI： 10.4028/www.scientific.net/KEM.516.36

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Optimization of Nozzle Flushing Method for Smooth Debris Exclusion in Wire EDM 査読

Takuya Fujimoto, Akira Okada, Yasuhiro OKamoto, Yoshiyuki Uno

PROCEEDINGS OF PRECISION ENGINEERING AND NANOTECHNOLOGY (ASPEN2011) 516 ( 516 ) 73 - + 2012年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：TRANS TECH PUBLICATIONS LTD

In a wire EDM using a thin wire electrode, better exclusion of debris from the machined kerf is important in order to maintain stable machining performance, since the area of spark generation is along a line and very small. When large amounts of debris stagnate in the gap, secondary discharges possibly occur and these discharges easily concentrate on the same location, which leads to unstable machining performance, wire breakage, low machining rate and a low shape accuracy.
Conventionally, the exclusion of debris is carried out by jet flushing with an upper and lower nozzle. However, the flow field of machining fluid in the kerf due to the jet flushing and the effect of jet flushing conditions from the nozzles on debris exclusion have not yet been sufficiently examined. This study aims to clarify the flow field in the machined kerf by computational fluid dynamics (CM) and to propose new jet flushing methods for smooth debris exclusion in the wire EDM. The effects of workpiece thickness and machined kerf length on the flow field of working fluid in the kerf under conventional jet flushing conditions are discussed. Then, jet flushing with a tilting nozzle is proposed in order to decrease the debris stagnation area near the wire electrode. As a result, by using the tilting nozzle, removal rate can be improved because of the smooth debris exclusion.

DOI： 10.4028/www.scientific.net/KEM.516.73

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Challenge to Development of Functional Multi-wire EDM Slicing Method using Wire Electrode with Track-shaped Section 査読

Yasuhiro Okamoto, Atsushi Kimura, Akira Okada, Yoshiyuki Uno, Jun Ohya, Toshiyuki Yamauchi

EMERGING TECHNOLOGY IN PRECISION ENGINEERING XIV 523-524 ( 523-524 ) 287 - + 2012年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：TRANSACTION PUBLISHERS

A newly developed multi-wire electrical discharge machining (EDM) method would accomplish the high performance slicing of silicon and silicon carbide with a narrow kerf width under a clean process environment. However, the thinner wire is challenging process with a normal round shape wire electrode. Therefore, a new wire electrode with track-shaped section was proposed in order to satisfy both the narrow kerf width and the high wire tension even in the case of thin wire electrode. In this study, the running control of wire electrode with track-shaped section was experimentally investigated, and the possibility of proposed process was discussed. A brass coated steel wire electrode with track-shaped section of aspect ratio 1:2 could perform the smaller vibration and the stable running up to 300 m/min. The side support method with fixture plates could improve the running stability of brass coated steel wire electrode with track-shaped section and reduce the kerf width. The brass coated steel wire electrode with track-shaped section could accomplish the uniform and straight kerf shape by increasing the wire tension.

DOI： 10.4028/www.scientific.net/KEM.523-524.287

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プラズマ窒化処理がステンレス刃物鋼の表面性状に及ぼす影響査読

玉置,植村, 岡田,宇野

精密工学会誌 78 ( 1 ) 72 - 76 2012年

Influence of Surrounding Gas Type and Pressure Condition on Micro-drilling Characteristics of Silicon Carbide by Harmonices of Nd:YAG Laser 査読

Yasuhiro Okamoto, Shin Urushibata, Akira Okada, Shin-ich Nakashiba Tomokazu Sakagawa

Proc. of 31st International Congress on Applications of Lasers & Electro-Optics 2012, pp.1269-1276 1269 - 1276 2012年

Velocity and Angle of Spatter in Fine Laser Processing 査読

Yasuhiro Okamoto, Hibiki Yamamoto, Akira Okada, Kento Shirasaya and Jari Tapanni Kolehmainen

Physics Procedia 39 ( 39 ) 792 - 799 2012年

Evaluation of Damaged Region at the Groove Edge of TCO Filim in Pulsed Fiber Laser Processing 査読

Yasuhiro Okamoto, Naoya Tkahashi, Shin-ichi Nakashiba, Tomokazu Sakagawa, Akira Okada

Proc. of 31st International Congress on Applications of Lasers & Electro-Optics 2012, pp.860-865 860 - 865 2012年

Singulation of Sapphire Substrate with High Aspect Ration Internal Modification by Sub-nanosecond Pulsed Fiber Laser 査読

Yasuhiro Okamoto, Kenta Takahashi, Akira Okada

Proc. of 31st International Congress on Applications of Lasers & Electro-Optics 2012, pp.813-819 813 - 819 2012年

Effect of Plasma Nitriding on Cutting Performance of Stainless Steel Cutlery 査読

Tsukasa Tamaoki, Akira Okada, Kensuke Uemura, Yoshiyuki Uno

Proc. Of 12th International Conference of euspen, Vol.2, pp.266-270 2 ( 2 ) 266 - 270 2012年

Micro-welding of Copper Plate by Frequency Doubled Diode Pumped Pulsed Nd:YAG Laser 査読

Shin-ichi Nakashiba, Yasuhiro Okamoto, Tomokazu Sakagawa, SunaoTakai and Akira Okada

Physics Procedia 39 ( 39 ) 577 - 584 2012年

Novel Approach for Slicing of Silicon Carbide by Multi-wire EDM using Wire Electrode with Trackshaped Section 査読

Yasuhiro Okamoto, Atsushi Kimura, Akira Okada, Jun Ohya, Toshiyuki Yamauchi

Proceedings of American Society for Precision Engineering 2012 Annual Meeting, pp.331-334 331 - 334 2012年

High-performance Micro-welding of Aluminum Alloy by Combination of Pulsed Nd:YAG Laser And Continuous Diode Laser 査読

Yasuhiro Okamoto, Shinichi Nakashiba, Tomokazu Sakagawa, Akira Okada

Proceedings of Materials Science & Technology 2012 Conference, pp.332-339 332 - 339 2012年

Applicability of Reactive Ion Etching to Fabrication of Micro-Prism Array for Dioptrics System 査読

Ryuto Fujie, Akira Okada and Yoshiyuki Uno

Proceedings of 10th International Conference on Progress of Machining Technology 227 - + 2012年

High-speed Observation of Wire Movement in Fine Wire EDM 査読

Sho Ichii, Akira Okada and Yasuhiro Okamoto

Proceedings of 10th International Conference on Progress of Machining Technology 215 - 218 2012年

Surface Modification of Cemented Carbide with Nickel Binder by Large-Area Electron Beam 査読

Akira Okada, Shuhei Misumi and Yasuhiro Okamoto

Proceedings of 10th International Conference on Progress of Machining Technology 207 - 210 2012年

Thermal Deformation in Micro-welding of Thin Stainless Steel Sheet by Single-mode Fiber Laser 査読

Yasuhiro Okamoto, Satoshi Matsuoka, Mohd Idris Shah Ismail and Akira Okada

Proceedings of 10th International Conference on Progress of Machining Technology 199 - 202 2012年

Evaluation of Molten Zone in Micro-welding of Glass by Picosecond Pulsed Laser 査読

Yasuhiro Okamoto, Isamu Miyamoto, Kristian Cvecek, Akira Okada, Kenta Takahashi, Michael Schmidt

Proceedings of the 13th International Symposium on Laser Precision Microfabrication (LPM2012), On-line, #12-63 2012年

ワイヤ放電加工用高性能ワイヤ電極の開発に関する研究（第４報）-ワイヤ表面の高抵抗層が放電加工特性に及ぼす影響− 査読

岡田晃, 山内俊之, 中澤正典, 清水敏明, 宇野義幸

電気加工学会誌 45 ( 109 ) 64 - 70 2011年

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