研究一覧（2004年1月〜12月）
レーザ切断における被加工母材の熱変形挙動に関する研究
布引雅之，奥田孝一，富田陽介
精密工学会誌，Vol.70,No.2, pp.257-262. (2004)
This paper deals with thermal deformation of a base material during laser cutting to avoid interruption in a long processing by the thermal deformation. The thermal deformation of a base material cut by laser beam was clarified experimentally. In experiment, the SUS304 sheets of 1mm in thickness were cut by several conditions, and we measured the residual heat, the flux of heat and thermal deformation of the cut sheet. In low-power and low-speed pulse beam cutting, both the residual heat and thermal deformation was lowest. In high-power and high-speed pulse laser cutting, the thermal deformation was larger than the deformation by CW laser cutting in which the residual heat was largest. It was clarified that the thermal deformation of the base material was influenced by flux of heat.
Returning Motion from the State of Falling Sideways for Articulated Mobile Robot
M. NUNOBIKI, K. OKUDA, M. HASEGAWA*
*Hyogo prefectural Tajima Technical Institute
JSME International Journal, Series C, Vol.47, No.1, pp.225- 232. (2004)
We developed an inchworm-type mobile robot. It consisted of only six segments connected by four pitch joints and one yaw joint. Although this robot had neither legs nor wheels, it was able to advance by using vertically undulatory motion of whole body. Even if it became upside down, it was able to move just like normal posture. But if it fell sideways, it was not able to move until returning to normal posture. In this study, we proposed a returning method by which the angular moment around roll axis was generated by twisting itself. To analyze this motion, we developed a mathematical model for this returning motion by considering the robot to be an underactuated mechanical system that consisted of a base frame and two link frames. We confirmed this returning
マグネシウム合金の超精密ダイヤモンド切削
奥田孝一
次世代を先導する生産加工に関するシンポジウム，pp.65-73 (2004)
生産拠点の海外シフトによる日本のものづくり技術の空洞化に対して，技術立国としての復権が求められていく中，「世界を先導していく生産加工」に関して，企業や大学の生産関係の研究者が集いシンポジウムが行われた．本著は精密加工セッションにおける講演発表資料として執筆されたもので，マグネシウム合金の超精密切削における加工特性，鏡面加工における加工技術的問題点，鏡面性状に対する金属組織の影響，作用メカニズムについて述べている．
マグネシウム合金板のCO2レーザ曲げ加工に関する研究（続報）−レーザ照射量が曲げ方向に及ぼす影響−
奥田孝一，戸田吉宣，布引雅之
2004年度精密工学会春季大会学術講演会講演論文集，pp.985-986 (2004)
The property of bending deformation in a laser forming of magnesium alloy plate has been investigated in the previous work. In the continued study, a feasibility of the control in the bending direction is examined. The experiments of CO2 laser forming of magnesium alloy plate were carried out under the machining conditions with a various laser spot diameter. When the focal point of laser is on the work surface, the plate bends toward the laser head. The bending angle decreases with an increase in the laser spot diameter and the plate bends toward the opposite direction at a certain diameter.
ニューラルネットワークを状態判別に用いた強化学習
前田俊祐，布引雅之，奥田孝一
2004年度精密工学会春季大会学術講演会講演論文集，p.839-840. (2004)
従来の強化学習では単一動作の獲得や最適化を対象とした研究が大半である．従来からの単純に状態を離散化するだけの状態分割では，複数の状態に共通した施策ベクトルを形成することは時間を要す．また，状態分割を行うために設計者の熟練を要する．そこで，本研究ではニューラルネットワークを用いることで状態の特徴を抽出し，同様の特徴を持った過去の経験で用いた政策を適用できる手法を提案する．
2003年度「機械工学振興事業資金助成」事業実施報告 「ロボットを作ってものづくりを体験しよう」
奥田孝一
日本機械学会誌，Vol.107，No.1025 pp.302-303．(2004)
「ロボットを作ってものづくりを体験しよう」というテーマのもと，ロボット製作を通じてものづくりの一端を実際に体験することにより，次世代を担う機械技術者を目指す若人にものづくりに対する興味を喚起するとともに，多くの人に機械工学あるいはメカトロニクス技術への理解を深めてもらおうと高校生対象に企画されたセミナーにおいて，「ロボット製作におけるものづくり技術」という講演とライントレーサロボットの製作実習の内容を報告．
Effect of Laser Irradiation on Bending Direction in CO2 Laser Forming of Magnesium Alloy Plate
K. Okuda, Y. Toda, M. Nunobiki
Proceedings of 7th International Symposium on Advances in Abrasive Technology, pp.513-518 (2004)This paper describes an effect of laser irradiation on a bending direction in a CO2 laser forming of magnesium alloy plate. In order to examine a feasibility of control of the bending direction and angle, the bending tests with a CO2 laser machine are carried out under the machining conditions of the various laser spot diameters by changing the focal point of laser. When the focal point of laser is on the work surface, the plate bends toward the laser head side without a failure. The bending angle decreases with an increase in the laser spot diameter and the plate tends to bend to the opposite direction of laser head at a certain diameter.
超精密切削を用いた厚膜フォトレジストの平坦化
奥田孝一
平成15年度設備管理学会講演会および兵庫県COEプログラム成果報告会，pp.5-6 (2004)
リソグラフィ技術は，ナノ・マイクロ領域の微細加工における中心的技術といえる．フォトレジストという感光性樹脂を基板上に塗布し，その上に光を透過する微細なパターンを持つマスクを配置して，写真の現像と同じ露光の原理でマスクのパターンを下地のレジストに転写する光リソグラフィが主に用いられている．さらに高精度な3次元微細構造物を製作していくためには，フォトレジスト層の平坦化が大きな課題となっている．また，平坦化された表面層にさらに積層していくことによって，複雑形状の3次元微細金型の製造技術への展開が期待される．基板上に塗布されたレジスト層は，ベーク処理の段階で熱収縮などにより表面に大きなうねりを生じる．これを平坦化するために本研究では，超精密切削加工機を用いて単結晶ダイヤモンド工具により，ベーク後あるいは露光後のレジスト層を直接切削することにより，表面粗さおよび平面度の高い表面層を得るための技術を確立しようとするものである．現像前に樹脂層を超精密ダイヤモンド切削することより，深さが均一なマイクロ構造体の作製が行える可能性を示した．
マグネシウム合金のCO2レーザ曲げ加工における熱伝導及び変形解析
奥田孝一，林田隼人，布引雅之
精密工学会2004年関西地方定期学術講演会講演論文集，pp.23-24 (2004)
近年，マグネシウム合金が種々の工業製品に適用されてきている．これらの多くは，ダイカストやチクソモールディングによる成形加工が施されているが，最近ではAZ31などの展伸材の曲げ加工，深絞りなどの塑性加工が試みられている．レーザによる曲げ加工は，金型や熱間装置を必要としないという利点があるが，実用化するためには曲げ変形量と曲げ方向が制御できなければならない．これまでに，レーザ出力，送り速度と曲げ変形量の関係が明らかにされ，レーザスポット径を変化させることで曲げ方向が変えられることが報告されている．レーザ照射時の板の温度変化や温度分布が，曲げ変形挙動に大きく関与していることは明らかであるが，実験的に把握することは困難である．そこで本研究では，マグネシウム合金板にCO2レーザを往復照射した場合の板の温度変化と曲げ変形を有限要素法を用いて解析することにより，主としてレーザスポット径の大きさが，温度分布や曲げ変形挙動に及ぼす影響について検討する．レーザスポット径を変化させることにより，レーザ照射部の局所的な温度上昇，板厚方向の温度勾配，加熱−冷却に伴う温度変動幅を変え，曲げ角度を変えられる可能性を解析により示した．
超精密切削加工を用いた厚膜フォトレジストの平坦化
奥田孝一，仲川周作，内海裕一，坂井信支，服部正
2004年度精密工学会秋季大会学術講演会講演論文集，pp.465-466 (2004)
To make three-dimensional micro structure by multi-layer LIGA-like process, a good surface flatness of photo resist is needed. This study introduces an ultra-precision cutting technology by diamond tool in order to fabricate a flat structure of thick photo resist. The steps of sample pattern and the surface roughness of resist are estimated. In result, the variation of steps was 2 μm or less, while it was 130 μm or more in the case that the diamond cutting was not applied. The roughness of finished surface by cutting was 0.1 μm in maximum height Ry.
マグネシウム合金板のCO2レーザ曲げ加工に関する研究 第3報 表面温度が曲げ方向に及ぼす影響
奥田孝一，戸田吉宣，布引雅之
2004年度精密工学会秋季大会学術講演会講演論文集，pp.733-734 (2004)
In the previous work, it was demonstrated that the bending direction could be changed by a variation of laser spot diameter in a laser forming of magnesium alloy plate. In this continued study, the relationship between the temperature change of the plate and the bending direction is examined when the cold air is sprayed on the surface. The application of cold air has changed the bending direction from upside to downside. A certain point of the plate bends upward during the temperature rise and bends downward on a larger scale during the temperature falling.
CO2レーザによるマグネシウム合金板の曲げ加工に関する研究
奥田孝一，布引雅之，下山昇吾，戸田吉宣
精密工学会誌，Vol.70, No.10 (2004) pp.1311-1315
The application of magnesium alloys to various products has been spreading. In this study, a laser forming of magnesium alloy plate was focused on. This paper describes the plastic bending properties and the deformation mechanism of magnesium alloy plate (AZ31) in CO2 laser forming. In order to investigate the characteristics in the laser forming of magnesium alloy plate, the experiments were carried out under the various conditions and the bending angle and the temperature of workpiece were measured by use of a laser displacement sensor and thermo couples, respectively. The results were discussed comparing with the results of stainless steel plate (SUS304). Based on the experimental results, it was found that the bending angle greatly depended on the surface temperature. The bending deformation increased with an increase of the laser power and the repetition of the heating-cooling cycle. The bending angle of the plate continued to increase while alternately repeating an upper and lower bend. The upper side deformation was larger than the reverse side.
6/4黄銅の超精密切削加工における被削性
奥田孝一，高井浩明
銅と銅合金（Journal of Japan Research Institute for Advanced Copper-Base Materials and Technologies），Vol.43，No.1 (2004) pp.269-273
This paper describes the micro machinability of free-cutting brass (C3604) and Pb-free brass (ECO BRASS) in an ultra-precision diamond cutting in order to investigate the effect of free-cutting additives on the cutting properties such as the cutting force, the surface integrity and the chip formation in the micro cutting with a single crystal diamond tool. The results are summarized as following.
(1) The cutting force was measured in the ultra-precision diamond cutting of C3604, ECO BRASS and C2801 for comparison. A remarkable difference among the three work materials was not observed. The principle force component of ECO BRASS became the largest at the condition of high feed rate.
(2) The surface roughness of ECO BRASS was the smallest and that of C2801 was the largest. Especially, at the high feed rate, the surface roughness of every brass became smaller than the theoretical roughness.
(3) The continuous chips were formed in the micro cutting of every brass, while the shear type of chips or the discontinuous chips were formed in the conventional cutting.
マグネシウム合金の単結晶ダイヤモンド工具による超精密切削加工
奥田孝一，竹野恵永
軽金属，Vol.54，No.11 (2004) pp.538-543
Magnesium and magnesium alloys are increasingly being applied for various products and the application to precise machine parts is expected. This paper deals with an experimental study of ultra-precision diamond cutting of magnesium and magnesium alloys. In order to investigate the micro cutting performance and clarify the problem in the generation of good mirror surface, the ultra-precision cutting tests of magnesium and magnesium alloys with single crystal diamond tool are carried out. The cutting force, the chip formation and the surface integrity of finished surface in the micro cutting are mainly examined and discussed. Consequently, it is observed that the specific cutting force and the ratio of thrust force to principle force significantly increase under the condition of smaller depth of cut. The mirror surface with roughness (Ry) of 100 nm or less is obtained in this experiment. However, Al-Mn compounds cause the scratches on the finished surface and deteriorate the surface integrity. The continuous type of chip is formed in micro cutting, while the saw-tooth type of chip is formed in the conventional cutting.
PTFEの超精密切削仕上面性状と表面機能に関する研究
奥田孝一，唐須崇，布引雅之
日本機械学会No.04-3第5回生産加工・工作機械部門講演会講演論文集，pp.19-20 (2004)
This study aims at clarifying the relationship between the surface integrity of PTFE finished by an ultra-precision diamond cutting and the adhesion strength of a metal thin film. As the first step of this study, the basic properties such as surface integrity in the diamond cutting of PTFE and the effect of the surface roughness on the textile water repellency are demonstrated in this report. The following remarks were found. The measured roughness of finished surface largely exceeded the theoretical roughness, while the cutting force was very small comparing with aluminum and the flow type chips were formed. The surface with a smaller roughness tended to repel water.
鉛添加および鉛フリー銅合金の超精密切削特性
奥田孝一
第44回銅及び銅合金技術研究会講演大会講演概要集，pp.109-110 (2004)
銅合金の被削性，特に工具寿命を向上させるために鉛を数%添加した快削性銅合金が様々な産業分野で用いられている．一方では，鉛は人体に有毒であるため鉛を含まない快削性銅合金の開発実用化も進められている．鉛やビスマスのようないわゆる快削添加物が切りくず分断性や工具寿命の向上に及ぼす効果については，これまで主として二次元切削実験に基づいて明らかにされてきた．これらの実験は，快削添加物や結晶粒の大きさに比べて切削変形域が十分大きくなるような大きさの切込みによるものである．著者らは，6/4黄銅の超精密切削特性を報告したが，このような極微小切削における快削性銅合金の切削特性については明らかにされていない．本研究では鉛を添加した快削黄銅と鉛を含まない快削性銅合金のダイヤモンド工具による超精密切削実験を行い，極微小切削における切削特性を調べた．その結果切削抵抗に関しては，材料による大きな差は無いがエコブラスの切削抵抗が若干大きくなった．仕上面粗さに関しては，エコブラスの粗さが最も小さくなり，特に高送り条件では理論粗さより小さくなった．また，全ての条件において流れ形の切りくずが生成した．
An Effective State-Space Construction Method for Reinforced Learning of Multi-Link Mobile Robot
M. Nunobiki, K. Okuda, S. Maeda
The 5th International Conference on Machine Automation pp.215-220. (2004)
One of the problems in reinforcement learning with real robots is to need a large number of trials. This paper proposes a reinforcement learning system that uses fuzzy ART neural networks for segmentation of state-space. By using an incremental state-space construction method with fuzzy ART neural networks, we are able to increase learning speed and reduce memory requirements. Whenever the fuzzy ART neural network encounters a new situation, it generates a new category node to the state-space. We proposed generating methods of a new category node that inherit the state-value and the policy from a similar node. Proposed methods were estimated from simulations of a two-link robot and experiments of a multi-link mobile robot. It was confirmed that the proposed method was able to increase the learning speed and reduce the size of state-space.
Effect of Al-Mn Compound on Mirror Surface Integrity in Ultra-Precision Cutting of Magnesium Alloy
K. Okuda, Y. Takeno
Progress of Machining Technology,Vol. 7, pp.209-214 (2004) .This paper describes an effect of the microstructure and the intermetallic compounds in magnesium alloys on the mirror surface integrity finished by an ultra-precision diamond cutting. The cutting tests of AZ31, AZ91 were carried out with the ultra-precision turning machine. It is found that Al-Mn compounds segregated in the microstructure of AZ31 play a role as the hard grain and generate the scratches on the finished surface, while Mg17Al12 segregated in the microstructure of AZ91 does not get involved in the generation of scratches. It is confirmed that the scratches dramatically decrease in the cutting of AZ31 with low Mn content.
Study on CO2 Laser Cutting of Magnesium Alloy Sheet
K. Okuda, M. Ueno, M. Nunobiki, Y. Shimada
Progress of Machining Technology, Vol. 7, pp.348-353 (2004).
This study deals with characteristics in a CO2 laser cutting process of magnesium alloy sheet. In order to investigate the basic machining property and clarify the problem in the laser cutting technology, a laser cutting test of AZ31 sheet was carried out by using a CO2 laser processing machine. By evaluating the height of dross, the width of kerfs and the roughness of cut surface, the effect of the machining condition on the cutting integrity is examined. The dross is more generated by a CW laser comparing with a PW laser. However, the flashlight and the sound are caused during a cutting with PW laser, especially under the condition of high laser power and low pulse frequency, while they are not generated during a cutting with CW laser.