3次元CADの普及に伴い,積層造形技術は,形状の数値化データから立体を直接製造できる効果的な技術として大きな成果を挙げてきた.
現在,従来からの樹脂中心のラピッドプロトタイピング技術では問題の多かった試作部門での利用方法に対処できる,新しい技術開発と,従来技術の適用可能範囲を拡大するためのラピッドツーリングに関する研究が,欧米の研究機関により積極的に進められてきている.ラピッドプロトタイピング技術は,技術開発により精度は年々向上し,さらに今なお新しい手法が続々と現れてきている.
積層造形法は,取り組むのは容易でそれなりのものは実現できるが,まだ産業界の望む精度を十分に達成しているとは言い難い.精度を向上させるためには,ミクロなレベルでの界面や接合,相変化等の基礎現象と精度との関係を解明し,制御することが必要となる.境界領域の技術を開拓してきた精密工学会の果たせる役割は大きいであろう.

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This paper deals with fundamental characteristic of the mechanism which consists of lever and toggle mechanisms. The mechanism is chiefly actuated by twin multilayer piezoelectric actuators. It can locate minutely and quickly for mechanical working and handling of some minute and thin objects. The lever members were made from a bimorph type piezoelectric actuator. As they were connected by elastic joints, the mechanism has no clearance and no friction. The mechanism is based on two concepts. In the first., mechanical stiffness of the members is variable and reinforced by additional electrical stiffness due to actuation of the bimorph members. Therefore the members can take smaller mechanical stiffness and inertia. The second, it can be variable input-output, characteristic of a piezo-stack actuator and correct deviated position of an output, point, by additional actuation of the bimorph members. With the experimental mechanism, the resolution is 1.57 μm.

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This paper reports study on a very small linear actuator which can have big force, long stroke and precise positioning capability. Although the actuator is driven by multilayer piezoelectric devices in cyclic way, small displacement is continuously transmitted to a slider through friction drive method. The spring plates which are fixed on both sides of the slider press the actuator grip points and the pressing force generates friction drive force. The maximum pressing force under which the actuator can work normally is calculated by FEM analysis. As a result, the actuator with an appropriate structure is designed, fabricated and experimentally evaluated. The factors which give effects to thrust force characteristics are studied.

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The development of an optical noncontact measuring instrument for the 3-D shape of an object with a free-form surface is described. The optical sensing system of the instrument proposed in previous work detects the depolarized component of light scattered from the object surface excluding specularly reflected light. Shapes of diffusive object surfaces and metal surfaces with both specular and diffusive components can be measured by use of the system. However, the properties clarified in the previous work were experimental results. In this work, the simulation of detection by ray tracing is described, for analytical clarification of the detection characteristics. The results of the simulation are compared with the experimental results.

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This paper deals with a method of collision check and collision avoidance on the tool path generation for 5-axis control machining. The proposed method is able to reliably check the collision between tooling system and objects which surround the tooling system. The method is to determine whether edges of polygon patches on the surface of the objects are intersecting to the tooling system or not. The avoidance value is quickly calculated in order to get tool posture without collision, when the collision is found. The CAM system has been developed in this study, and it has been applied to machining for a marine propeller. The validity of the proposed method is experimentally confirmed by the machined propeller and its measured result.

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本論文では,板金製品の干渉を生じない全曲げ手順を高速に算出するアルゴリズムについて議論した.このアルゴリズムは,干渉検出のための幾何計算や干渉判定の回数を低減することで,高速な処理を実現する.特に過去の干渉判定の結果を再利用することで,大幅な高速化を達成した.提案したアルゴリズムに基づいてプログラムを作成し,計算実験によりその性能を検証した.このプログラムは,曲げ部の個数が10を越える複雑な板金製品でも,対話的な利用で支障を感じない時間で全曲げ手順を生成できる.
作成したプログラムは,アルゴリズムの評価のためのプロトタイプであり,実用化のためには以下のような課題が残されている.
(1)現状では,V字型の金型を用いる単純な曲げ加工だけを想定している.より複雑な加工法も扱えるように,板金モデルや干渉の検出手法を拡張する必要がある.
(2)実際の曲げ加工では.製品の精度や加工コストなども考慮して,最適な曲げ手順を決定している.曲げ手順探索の際に,このような技術的な制約や経済的な制約も評価することで,プログラムの性能の一層の向上が期待できる.
本研究の成果を,板金製品の実用的な工程設計システムや順送金型の設計支援システムへ発展させたいと考えている.

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ファインセラミックスの高能率・高平滑研削加工法の開発を目的として,粒度#140の粗粒メタルボンドダイヤモンド砥石による延性モード研削の可能性を検討した.工作物には,ホットプレス法と熱間静水圧法で製造された炭化けい素(HPSC)と窒化けい素(HIPSN)を用いた.主な結果は以下の通りである.
(1)粒度#140のメタルボンドダイヤモンド砥石でHPSCおよびHIPSNの両ファインセラミックスとも,テープル速度を遅くすると10×10mm²全面にほとんどぜい性破壊がない延性モード鏡面研削が吋能てある.
(2)同じ研削条件で,連続切れ刃間隔がはるかに知い粒度#800の砥石では,全面での延性モード研削が出来なかった.粒度#140の砥石の砥粒の大きな切れ刃逃げ面が延性モード研削に関係していることか考えられる.
(3)仕上面全面で延性モード研削となるようなテーブル速度の遅い条件では,表層の硬さは幾分か低下する.
(4)仕上面粗さは,テーブル速度を遅くすると向上する.V_w=0.05mm/sのHPSCの全面延性モード研削の場合,研削方向と平行方向の仕上面粗さおよびそれと直角な砥石軸方向の仕上面粗さはそれぞれ約20nm(R_z)と240nm(R_z)になる.
本研究の実験に協力頂いた工藤裕幸,山浦光男,田中慎一,河村強の各氏ならびに研削盤,砥石,研削液,工作物のご提供を頂いた(株)岡本工作機械製作所,ノリタケダイヤ(株).ユシロ化学工業(株),東陶機器(株)の各社に謝意を表します.

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This paper proposes a method to measure the wire temperature in wire electrical discharge machining utilizing the relationship between the wire temperature and the sensitivity change of the method of measuring discharge location. The measured wire temperature ranges wide up to 180°C depending on the cutting conditions such as discharge current, discharge frequency, wire winding velocity and flushing conditions of the working fluid. Based on the measured wire temperature, the mechanism of wire rupture is discussed taking into account the wear of wire electrode.

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Aspherical lenses of single crystal silicon (Si) are used for the scope and the camera of infrared wavelength, because the very large refractive index of the material leads to substantial reflection loss. These aspherical lenses of infrared wavelength materials were manufactured by diamond cutting. But the single crystal silicon is a hard and brittle material, it is difficult to obtain a mirror surface without a micro crack when the lens diameter is large. In this case, aspherical polishing has to be applied after diamond cutting in order to generate an aspherical surface most precisely. In this study, a computer controlled polishing system using a small rotating polisher was developed for precision finishing of a large size of aspherical surface after diamond cutting. The characteristics of this polishing system are, as follows: (1) A disk shape of forming polyurethane pad was used as the polishing tool, and its rotating axis was controlled to be always normal at the machining point of the workpiece surface. (2) The polishing load was applied from the normal direction of the machining point and controlled to be constant. In the aspherical polishing tests, spherical surface of diamond turned single crystal silicon (111) was polished to generate an aspherical shape. As a polishing abrasive, colloidal silica was used. As a result, a form accuracy of about 0.2 μm P-V (±0.1 μm) and a surface roughness of less than 0.02 μm Rmax were obtained.

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This paper presents newly developed force controllable measurement probes which will be used for profile generation with using no external reference. These probes are able to perform measurement and fabrication simultaneously. Measurement ability of probe type 1, which has cantilever and lapping pad, is tested experimentally. The results of this experiment indicate that the repeatability error increases with measurement force, because the lapping pad inclines when it is pressed to the test surface. Probe type 2 is developed to solve this problem. Both lever ends of this probe are held by piezoelectric actuators, and the pad is attached to the center of the lever. Control system of this probe is decided form consideration of lever inclining. It is appeared that the probe type 2 has better measurement ability than probe type 1 from experimental result. In-process measurement by using probe type 2 is tested. A silicon wafer is machined by this probe under the non-linear control mode. Relation of machined amount between lapping force and machined amount between time are investigated basically.

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本論文では大型工作物への局所的な精密加工法の一つとして,インパクト駆動機構を用いた自走式放電加工機を提案し,試作した加工機に関する実験を行った.結果をまとめると以下のようになる.
(1)xy軸方向に移動しながら連続した穴を加工した.その穴を測定した結果,約5mmの移動に対して直線からのずれは0.05mm以下,角度の誤差は0.4°であった.
(2)x軸方向にサーボをかけて電極側面を用いて溝加工を行った.z軸送り部だけでなくテーブル部も放電加工を行うのに十分な応答性を持つと考えられる.
(3)電極送り機構の運動とテーブル部の運動の間では干渉は起こらなかった.
今後は,本方式と立体を校正基準とする機上計測法を組み合わせ,小型形状測定機械を移動基準面の上で移動させることで,加工結果の形状や表面粗さ等の測定を行うシステムを構築することを検討する予定である.

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Aramid fiber reinforced rubber (AFRR) is one of advanced composite materials, which have some excellent characteristics transmission belt. V-ribbed belt is formed by grinding to generate not only the required shape but the suitable frictional characteristics on contacting rubber surface with a pulley. The frictional characteristics of AFRR V-ribbed belt is sensitively affected by projecting condition of aramid fiber whose coefficient of friction is much lower than that of matrix rubber. In this paper, form grinding mechanism of AFRR V-ribbed belt with diamond wheel is experimentally investigated by analyzing form accuracy of V-groove and projecting length of aramid fiber. Furthermore, an estimating method for the coefficient of friction of AFRR V-ribbed belt is proposed by clearing up effects of each factor on the coefficient of friction of V-ribbed belt. Main conclusions obtained in this paper are as follows: (1) Coefficient of friction of AFRR V-ribbed belt is decided by V-groove angle and projecting fiber length on the surface generated in form grinding, and it decreases with increases of V-groove angle or projecting fiber length. (2) Coefficient of friction of V-ribbed belt can be estimated by subtracting the decrease from coefficient of friction caused by projecting aramid fiber from the coefficient of friction decided by V-groove angle of matrix rubber belt without projecting fiber. (3) Both V-groove angle and projecting fiber length increase with an increase of curvature of V-ribbed belt in form grinding process.

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The present paper deal with the unique fabrication of Fresnel zone plate(FZP) by laser direct drawing and with the step blazed FZP by glass etching, in addition, its optical characteristics experiment. The FZP is the typical diffractive optical element(DOE), and superior in many characteristics to the other elements such as refractive lenses or reflective mirrors. There are several means to fabricate the FZP, direct laser drawing is used for convenience. The computer generated holography(CGH) method is used efficiently for the pattern generation.The FZP composed of photo resist thin film is fabricated by laser direct drawing and 2, 3 and 4 level step blazed FZP is fabricated by repetition of direct drawing and glass etching. Diffraction efficiency and focusing characteristics are evaluated for various groove depth. In relation to diffraction efficiency, 89 to 97% of theoretical value is achieved, and the maximum efficiency is proved to arise at reasonable depth of the groove.The FZP fabricated is able to focus the laser beam to the theoretical limit.

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Simplified model to estimate a rolling friction of a roller is given in this paper. In this model, it is assumed that a Hertzian elliptical contact pressure distribution pattern changes when a tangential force acts upon the rolling element. Approximating that the ground surface of the rail is composed of many small cylinders, a rolling friction and a transient displacement characteristics can be calculated from experimental parameter values. And the transient rolling state can be connected with the continuous rolling state by nondimensional parameters which are independent of surface roughness of the rail, diameter of the roller and preload.

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In this paper, a new electrical discharge machining (EDM) of insulating ceramics with an assisting electrode and its machining mechanism are described. The proposed method is available for machining a complex shape on insulating ceramics. In experiments, insulating Si3N4 ceramics is machined with an electrical conductive plate as the assisting electrode in working oil. The machining starts on the assisting electrode. When the tool electrode reaches at the interface between the assisting electrode and the insulating ceramics, the machining does not proceed for several minutes. In this period, discharge concentration or short circuit state occurs frequently, and an electrical conductive black layer generates on the ceramics surface. After complete formation of the black layer at the interface, machining of insulating ceramics progresses in stable; meanwhile, the black layer is continuously generated on the ceramics surface. This black layer consists of turbostratic carbon and α-SiC. The equilibrium phase diagram of carbon and silicon explains the formation of the black layer. Fundamental technology of machining insulating ceramics into complex shape by EDM has been established through the above consideration.

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The internal surfaces of hole of the single crystal diamond die for wire drawing are composed of the various crystallographic orientations. A manner of representation of the diamond crystal planes and the directions rubbing with wire is proposed. It is shown as the diagram of crystallographic orientation on developing chart of diamond reference sphere expressed in the restricted Mercator's projection. The distributions of frictional force ratio on the die hole, curvature and curved direction of drawn wire, distribution of hardness on outside of drawn wire are measured, and the relation among them are discussed. The results are following: the drawn wire bends to the direction of small frictional force ratio on the diamond die hole and the surface hardness of drawn wire is higher on the surface of outside of curved wire.

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This paper describes a new large surface heat treatment method with a high power CO₂ laser. The main feature of this method is to control the heat input on the surface of a carbon steel plate using a truncated pyramid mirror optical system and divided laser beams. A truncated pyramid mirror optical system enables to have a straighter beam trace on the surface than that by conventional polygon mirror system. This optical system can irradiate laser beams into a line at the surface of specimen. Each laser beam is located at the same interval. A 15kW CO₂ laser and a 6 truncated pyramid mirrors are used for experiments to evaluate the new method. A large surface hardened zone without tempering on a carbon steel plate is achieved. The size of hardened layer is 60mm width, 0.6mm depth and 16mm length. This method would be very effective for continuous heat treatment of a very large steel plate without tempering.

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