[in Japanese]

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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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In the sheet metal part manufacturing, bending is the most commonly used to realize sufficient rigidity and to obtain a part of desired shape to perform a certain function. Feasible bending sequences of a sheet metal part can be determined by successively applying bending simulations to the geometric model of the part. This simulation based method is computationally expensive because huge number of sequences must be explored if a part with many bending portions is given. In this paper, the authors propose a method to accelerate the simulation based sequencing method. Complicate parts with many bending portions usually have rather small number of feasible sequences because other sequences cause self interferences or collisions with tools in the bending operation. Our method reduces the computation cost by efficiently detecting such interferences and collisions in the early stage of the sequencing process. The collision information record is introduced which enables multiple use of the collision check result computed in the prior process. The proposed method is implemented and an experimental bending sequencing program is demonstrated. This program can derive all feasible bending sequences of complex sheet metal parts in an interactive speed.

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The possibility of the ductile-mode grinding of fine ceramics by the metal bond diamond wheel of grain size of #140 is investigated by grinding hot pressed silicon carbide (HPSC) and hot isostatic pressed silicon nitride (HIPSN). The experiments are executed in plunge-cut grinding method with conventional surface grinder. The wheel speed used is 20m/s. The table speed, v_w ranges 0.05mru/s to 5mm/s. The ground workpiece surface is observed with differential interference microscope and SEM, and its roughness is measured with the ordinary stylus profilometer, WYKO and AFM. The ductile-mode grinding of HPSC and HIPSN by #140-wheel is possible at v_w=0.05m/s over almost whole workpiece surface of 10×10 mm² without brittle fracture. By #800-wheel which has much shorter successive cutting edge spacings than #140-wheel, the ductile-mode grinding is inadequately possible. The hardness of the high ductile-mode ground surface layer is somewhat smaller than that of the original raw material. The large wear area of cutting edge on #140-wheel surface is considered to relate to the ductile-mode grinding. The surface roughness of both HPSC and HIPSN becomes smooth as the table speed decreases. When grinding HPSC at the table speed of 0.05m/s by #140-wheel, the surface roughness parallel and normal to grinding direction are below about 20nm and 200nm, respectively.

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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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An electrical discharge machine of a self-running type (a movable electrical discharge machine) is developed to machine fine structures on a local area of a large workpiece. This electrical discharge machine consists of two parts; a mobile table and an electrode feeding device. This machine moves on the workpiece by the Impact Drive Mechanism which utilizes rapid deformations of piezoelectric elements. It measures approximately 130×130×140 mm and weights 700 g. A control method of the mobile table is introduced. The direction of the movement depends on the ratio among the applied voltage of the piezos. Then the interference of the movement among the axes and the machining performance arc investigated experimentally. Holes and grooves can be machined with the electrical discharge machine of the self-running type.

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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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