This paper describes a link layout design problem for six degree-of-freedom fine motion stage using Stewart platform mechanism. Isotropies of the translational and rotational stiffness, the generated force of the stage, the force acting on the link and the positioning resolution are investigated by singular value decomposition in various link layout. The obtained main results are as follows. (1) The translational stage stiffness in XYZ directions is unified at optimum stage height. The height is dependent on position angle difference between the stage joint and the base joint and is independent of the stage radius. (2) The translational positioning resolution, the generated force of the stage and the force acting on the link are unified with optimum stage radius, when the angle between the links and the base plane is 35.23°. (3) Optimum relation between the stage height and the stage radius exists to make the rotational stiffness in αβγ directions equal, when the angle between the links and the base plane is 54.7°. (4) The link layout which unifies simultaneously the translational stiffness and the rotational stiffness has not been found.

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Acquiring profile data and producing CAD models are indispensable to style designing based on a master model. Therefore the present studies aim to generate high-quality CAD models from measured point data on a master model which has free-form surfaces. In the former report, a method to measure a master model, that is, boundary high-density measuring, and a method of character-area extracting were proposed. This paper describes a strategy of remeasurement in extracted character-areas and one technique to generate free-form surfaces from the measured point data acquired by the remeasurement. The master model is measured with a non-contact 3-D digitizing system developed by the authors. In the remeasurement, a patch on each hierarchical structure is divided into four parts in a quadtree method, and a uniform cubic B-spline curve fits onto the measured point data. The fitted patches are connected to subdivided ones and they together can form the free-form surface of the master model with their adjacent patches conforming to the C2 continuity. New techniques are also proposed for connecting B-spline curves with surfaces by use of pseudo vertices. The results of inspection experiments with the measured point data confirm the availability of those methods.

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A method for measuring particulate sizes of nanometer (nm) order on an ultraprecisely-machined surface has been developed using a laser light scattered method. In this papa-, we proposed a new method to detect particles of a 6 nm particulate diameter on a raw Si wafer, and developed the measuring system having a detection sensitivity of a 19 nm particulate size with this measuring theory. This system is more than one order of magnitude higher than that of the conventional method. This, a new system was developed with a CCD sensor to simplify the setting of the optical system and with automated measuring apparatus for application in the ultra-clean room of class 1. To evaluate this measuring system, the measurement of particulate sizes was attempted with a standard particle. It was verified that this measuring system could measure the particulate size in a detection sensitivity of 24nm on an ultraprecisely-machined surface. Furthermore, it was used to detect particles on the surface of the raw Si wafer ; particles corresponding to a particulate diameter about of approximately 24-34 rim could be detected. In addition, to verify the measured particle, wet cleaning for the Si wafer was attempted in the ultra clean room. Consequently, it was verified that detected particles on the raw Si wafer were foreign particles and that the wet cleaning is an effective method to remove particles of less than 0.1μm diameter on Si wafer surface.

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This study deals with the post-process measurement of the grinding wheel topography by means of a newly improved image processing system. In this system, grinding wheel is driven by the high-power electric servomotor with a built-in rotary encoder so that both grinding operation and consecutive measurement of the individual abrasive grains by the accurate wheel positioning are possible. The contraction/expansion process is useful for the separation of adjacent grains. The dark field microscopy is effective in order to extract monochromatic CBN grains from the lustrous metal bond. This system is applicable to the practical grinding operation with resinoid and metal bonded superabrasive wheels with a good degree of accuracy and efficiency. In grinding normally sintered silicon nitride with the resinoid-bonded diamond wheel at a given grinding condi-tion, this system reveals that cutting-edge ratio decreases rapidly due to the micro-fracture of grain tips at the transient stage just after truing/dressing, and it increases slightly with the promotion of attritious wear under the successive steady state. This phenomena are explained by the fact that abrasive grains are damaged during truing/dressing operation.

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This paper deals with an stage for a scanning probe microscope (SPM) by using a Stewart platform type parallel mechanism with 6 degrees of freedom. Stacked piezoelectric actuators are used to change link length in a prototype. The movable range of the prototype is 100μ in the x and y directions and 201tm in the z direction. The resonant frequency of the prototype is 100 Hz in the x and y direction and 75 Hz in the z direction approximately. The table motion is controlled by the induced charge feedback control to allow compact SPM designs. The motion error is 16 nm in the z direction by the induced charge feedback control. The displacement of the prototype can be controlled by the induced charge feedback control as well as by the displacement feedback control. This stage is applied to a positioning device of an atomic force microscope (AFM). The grooves of a diffraction grating are observed with good linearity. The prototype can be used for the positioning device of the AFM.

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This paper concerns the problem of the fast and high accurate mass measurement under the conditions of floor vibration. A specific type of weighing machine, which consists of a weighing loadcell and the dummy loadcell to cancel the undesirable influence from floor vibration, is considered. To improve the accuracy of mass measurement, it is necessary to compensate the difference in dynamics between the two loadcells. For this purpose, a mass measuring algorithm, which makes use of the numerical model of a loadcell, was proposed in the previous paper. The numerical model is obtained on the assumption that the loadcell is regarded as a spring-mass system of 1 degree of freedom. However, there are also some cases where the differences in dynamics between the two loadcells may not be compensated correctly even if the proposed algorithm is used, because the assumption may not be satisfied. Therefore, in order to compensate the difference in dynamics between the two loadcells correctly, a new algorithm, which uses the approximate model of polynomial function, is described in this paper. The effectiveness of the new algorithm is certified by experiment.

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Precise profile measurement has been required in various fields such as industrial fields and medical fields. For such a request, a measurement method using moiré technique has been proposed. In this research, for profile measurement of objects, shadow moiré topography using phase shifting technique is proposed. However, in shadow moiré topography, shifting phase of moiré pattern regardless of fringe orders is not easy because fringe interval varies according to the fringe order. A trial to shift a phase constantly regardless of fringe orders is proposed by giving vertical movement and rotation to the grating. Availability of this technique is justified by a simulation test and some experimental results reveal the verification of this research.

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A low coherence interferometry is a method for non-invasive optical ranging measurement of microstructures. A simultaneous measurement method of geometrical thickness and refractive index of quartz crystal with the low coherence interferometry has been proposed. However, it is hard to align a sample arm in the Michelson interferometer, because a beam of measurement arm must be incident on both sample and measurement mirror. Moreover, only the geometrical thickness and refractive index at the edge of sample can be measured. In this study, a novel configuration of low coherence interferometer is proposed in order to solve these problems. This system utilizes double Michelson interferometers. The interferometer consists of two reference mirrors which are used for scanning an optical path length and for determining a reference point. Both distributions of geometrical thickness and refractive index with this method can be measured. An experimental verification of our method is demonstrated by the use of microscope glass cover-slip and quartz crystal as samples. It was found that the measurement values of samples were in good agreement with the thickness measured by a dial gauge and the refractive index cited from the literature.

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Molds and dies with sculptured surfaces are usually fabricated using numerically controlled (NC) 3-axis milling machines with a spherical cutter. Most CAM systems compute the tool path using the geometric model of designed surfaces in a semi-automatic manner. In order to detect potential problems of the tool path, geometric verifications of the NC milling result are necessary prior to actual machining. Result shape of the workpiece can be computed by subtracting successive tool swept volumes along the path from a solid model representing the stock shape. In this paper, the authors propose an acceleration method of the subtracting operations using the hidden-surface elimination mechanism of the 3-dimensional graphics acceleration hardware. Computation time of the proposed method is basically proportional to the total number of polygons approximating the component surfaces of the swept volumes. Some portions of the component surfaces do not contribute the result shape of the workpiece. Our algorithm reduces the number of polygons by properly excluding such surface portions from the tessellation. An experimental program is implemented and geometric verifications of some sculptured surface milling operations are demonstrated. The program can visualize the complex milling result in a few seconds.

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YAG laser has widely been used for precision micro machining in many fields. However, adhesions of dross and spatter to base material due to high energy beam machining lead to the deterioration of surface integrity. It is important to understand the assist gas flow from the tip of a convergent nozzle in order to improve the machining accuracy, since most materials are removed away by gas flow. In this paper, the effects of assist gas flow on machined results in micro machining with pulsed YAG laser are investigated using Schlieren method. Experimental analysis made it clear that there was a region in which the pressure on workpiece didn't increase linearly with an increase of cylinder gas pressure. Mach shock disk repeatedly appeared and disappeared under this condition, and the pressure on workpiece changed periodically. The fluctuation of assist gas flow led to the irregular dross generation. On the other hand, there was no unstable region under small gap and/or high pressure conditions, in which the assist gas flow was stable and the height of dross became smaller. Consequently, it is recommended to use the assist gas under higher pressure condition more than 300kPa on workpiece for fine precision machining.

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This paper clarifies the generating mechanism of machined surface by ball-nosed end milling through geometric analysis. The problem definition is to determine a height of cusp at a voluntary position in milling a spherical surface with a plane cutting edge of straight flute. It is assumed that tool axis is on the plane perpendicular to the feed direction. The necessary and sufficient conditions for identifying the tool rotating angle and its cutting edge at the specified position are originally formulated and their solving procedures based on Newton-Raphson method are mentioned. The number of solutions in these conditions is analyzed and explained geometrically. It is found that a certain area is cut maximum three times by the same edge, regardless of its edge shape. The machined surface by the two and three flutes of end mills are simulated and illustrated graphically with use of a geometric modeling system. A machined surface is illustrated as a combination of colored area corresponding to applied cutting edges, and it is helpful to understand the generating mechanism of machined surface. The computing time to detect the shape of cusp is about one third of that by a previous method reported. Conclusions are briefly mentioned.

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This paper introduces a new damage free machining method for hard-brittle materials; machining under high hydrostatic pressure. A new machining equipment, in which scratching test can be performed under high hydrostatic pressure of 400MPa, was developed. Silicon wafer and silicate glass were applied to this equipment to evaluate effects of hydrostatic pressure on their ductile-brittle transition. Results show drastic decrease of machining defect and increase of critical groove depth by hydrostatic pressure. This paper also discusses origins of machining defect, and indicates that defects are attributed not on microcracks on the surface of workpieces but those in workpieces. It also points out a problem of the initial crack model of machining defect generation.

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Recently, short-pulse lasers have been applied to microprocessing in the field of various industries. It becomes more difficult to experimentally observe the microprocessing phenomena as pulse width becomes short. Numerical analysis with a continuum model has a limit in elucidation of such phenomena, therefore, computer simulations at the atomic or molecular level must be important. The authors have carried out the molecular dynamics simulation of laser materials processing. In this paper, a modified molecular dynamics method for metal developed by the authors, in which calculation of the molecular dynamics is carried out compensating the heat conduction by free electrons at each time step, was applied to elucidate the laser microprocessing phenomena. Pulse width dependence of damage threshold, evaporation process, velocity distribution of evaporation particles and temperature profile in the material were investigated.

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This paper proposes a method to control the discharge location in the electrical discharge machining. The method is based on the fact that when a high-voltage is applied with a sufficiently short rise time at a certain point on the tool electrode the gap voltage close to the point is transiently greater than that of another location because a finite time is necessary for the potential to be transmitted through electrically conductive materials due to inductance. This principle was applied to the wire electrical discharge machining (WEDM) and the discharge location was controlled by superimposing a high-voltage on either the upper or lower feeding brush. Experimentally it was verified that the discharge location can be controlled using this method and that the material removal rate can be increased by dispersing the discharge location on purpose.

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The new functional materials have been studied to apply to micro machines or electronic devices. However in order to develop new materials, it is indispensable to control the film thickness of nano-meter or sub-nanometer and to deposit the fine film of the same roughness as substrate surface. This paper describes the experimental results, the possibility to fabricate metal films of nanometer order thickness and to synthesize new materials of multilayer structure using the Knudsen-cell in the high vacuum MBE chamber. The structure of the films was analyzed by X-ray diffraction.

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This paper describes the cutting performance of diamond coated cutting tool prepared with cobaltless tungsten carbide (WC) sintered by spark sintering. The mechanical strength of cobaltless WC cutting tools has been confirmed by turning gray cast iron (FC250). In order to prepare diamond coated cutting tool, diamond film was deposited on the cobaltless WC by microwave plasma CVD and hot filament CVD. The performance of the diamond coated tool has been evaluated, by turning A1-18% Si alloy. As the result, it is found that the diamond coated tool which leads strong adhesion to diamond film can be produced by using cobaltless WC of which sintering density ratio is 70-90% and thickness of coated diamond film is approximately 20 μm.

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Diamond turning of single-crystal silicon was carried out in the (111) and (001) wafers, and then the influence of the rake angle of the cutting tool on the ductile-brittle transition mechanism was studied. The material removal process occurred more plastically when using a cutting tool with a larger negative rake angle on both wafers. This was mainly due to changes in cutting-force direction with rake angle. In the case of the (001) wafer, the experimental result could clearly be explained by the differences in the tensile stress exerted on the {111} cleavage planes. That is, the amplitude of the tensile stress decreased as the angle between the cutting-force direction and the cutting direction increased. However, ductile-brittle transition behavior in turning the (111) wafer can not be fully explained in the same way. Transmission electron microscopy observations revealed that activated slip systems on the (111) plane parallel to the turned surface helped to promote ductile behavior. These results indicate that ductile-brittle transition depends, not only on the amplitude of the cutting force, but also on the slip systems to be activated

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