This paper presents the development of a system for measuring a positional vector and a unit normal vector of a point to be measured, and proposes new measuring methods of dimensions such as a distance between parallel planes and radii of a cylinder and a sphere. The system is constructed of a CNC three coordinate measuring machine and a newly developed probe which consists of a quartz glass ball with a thin resistant film of TiN and four electrodes of Au. Since the probe is able to directly detect the contact point between the probe and an object to be measured, the system is able to measure a position vector and a unit normal vector of the contact point. The measuring accuracy of the system is 0.1 degree in the directions of θ and φ which are spherical coordinates to indicate the normal vector. The proposed methods are based on measurements of position vectors and unit normal vectors, and obtain two-fold and three-fold measuring efficiency in comparison to conventional methods. The usefulness of the proposed methods is confirmed by experiments of measurement of a block gauge, a cylinder gauge and a steel ball.

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A new mechanism using DC servo motor for coarse motion control and piezo-electric actuator for fine motion control has been developed. This dual-drive system is capable of controlling robot's motion with relative accuracy in the order of 10^-6. A robot with two degree of freedom using this dual-drive system has been developed and tested. Experimental results indicate that the positioning accuracy is ± 0.5 μm for PTP motion and ± 0.1 μm for CP motion. The piezo-electric actuator is used not only for fine positioning but also for absorbing residual vibration of the coarse actuator. PID feedback control of position error is used and an efficient method for determining the feedback gains is proposed. Experimental results show that this control method is effective for high speed and high accuracy motion control of a precision robot.

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An alignment mark illumination and detection technique is described in which the alignment error caused by the alignment pattern depth and the resist thickness asymmetry is reduced. For the alignment mark, a diffraction pattern which gives a high contrast signal is used. 2-wavelength laser (488, 543 nm) is diverged in 2 directions by a double refraction prism and illuminates the alignment mark vertically and with 26.2 degree inclination. The first order diffraction light is detected. The variation in the detected signal is 30% in the range of 0.6-2.5 pm of pattern depth and resist thickness, compared with the signal detected by the single wavelength light illumination. The experimental result gives a detection error of ± 0.045 μm (3σ) for a wafer in the worst condition.

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In the present paper, a link-arrangement system for spatial mechanisms with consideration of mutual interferences among moving links is investigated. In order to determine optimum profiles of links which satisfy the minimum moving space of the mechanisms, a rotary plane which arbitrary fixed on one of the moving link in the mechanism is introduced, and relative loci of pairing points and positions of links with this plane are analyzed. Moreover, conditions to determine link arrangements avoiding mutual interferences of moving links are formulated. Based on the above analytical results, a link-arrangement system is constructed which obtains the optimum profiles and arrangements of links of spatial mechanisms. Applying the system, a spatial 4-bar mechanism is synthesized as a practical example.

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A coordinate measuring system with two target-tracking laser interferometers is developed. Each interferometer measures the radial distance between the corner point of a target cornercube mirror and the rotation center of the tracking. 2 D coordinate value of the corner point is computed from these radial distances and a priori known distance between the rotation centers. Experimental comparisons between the system developed and a commercial coordinate measuring machine (CMM) shows that the accuracy of the coordinate measurement in the system is better than 1 μm, regardless of the absolute distances. The problems of the present system and the extension of the system to three-dimensional measurement are discussed.

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In this paper a numerical technique and simulation models are described to analyze flow patterns around prosthetic heart valves under steady flow conditions. The finite difference method was employed to solve the time-dependent and non-linear Navier-Stokes equations (NS eq.) for an incompressible viscous fluid. Chorin's scheme was used to solve the governing equations, NS eq. and equation of continuity. In this method the discretized algebraic equations approximating the governing differential equations were obtained from the analytic solutions of the governing equations ; this method was shown capable for providing a stable numerical solution and a proper simulation of the flow dynamics. The flow geometry, including a flow chamber and a prosthetic heart valve, was overlaid with a rectangular grid. The several types of clinical valves and the trial model valves developed in our laboratory were chosen as subjects of this study.

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In this paper, the shaft response characteristics of hydrostatic thrust gas bearings with fluid damper are described. In hydrostatic gas bearings, the both clearances at which stiffness reaches its maximum value and damping reaches its minimum value are well known to be at almost the same. Therefore, when an impact force acts on the shaft, the shaft response behavior of vibration generally shows under damping, and it takes several times of the natural period in convergence. So, the possibility of reducing convergence time is examined by the use of fluid damper. Following conclusions are obtained : (1) The shaft convergence behavior of vibration can be improved (from under damping to critical damping) by changing the damping coefficient of fluid damper. (2) The shaft convergence can be achieved in about one natural period. (3) The optimum damping coefficient of fluid damper is set at 0.6-1.0 of damping factor in the bearing system. (4) Fluid damper can be of great help to make high stiffness gas bearings with large pocket in the bearing surface without causing pneumatic hammer instability.

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This paper deals with a digital position servomechanism with one-sample delay including a second-order oscillatory element for providing design criteria of its sampling period. At first, all of parameters in the servomechanism are normalized by using a natural angular frequency of the element, then a relation between a sampling period and a critical control gain with respect to a damping factor of the element is analyzed. As the results of analysis, the design criteria are characterized by the damping factor ζ into two cases. In case of ζ>0.2, the shorter sampling period is desired for its stability as usual discussions. However, in case of ζ<0.2, an unique result is obtained that a nonzero optimal sampling period exists, i. e. a normalized sampling period should be equal to 1.7 for stabilizing the servomechanism. Finally, the results of the analysis are verified by some experiments.

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This paper offers an over-sampling method combined with zoom-FFT. The method is one of the methods which increases the resolving power of frequency in FFT analysis, and has the feature that it can choose arbitrary zoom ratio, i.e., arbitrary magnification of the resolving power of frequency. The results of investigation on the method are as follows : With the zoom ratio which make the fraction of normalized frequency some integer, the frequency component can be exactly extracted on its correct position; Smallest zoom ratio is sufficient for analysis; For Hamming window, the resolving power of two components is 2-normalized frequency under a zoom ratio smaller than 30; If the distance between two components is larger than 6-normalized frequency, Hanning window gives exact analysis with an amplitude error smaller than 0.1% and a phase error smaller than 0.1 degrees.

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Information integration method has features, one of which is that it can evaluate a number of evaluation items of different characters totally and rationally. This paper deals with a system based on this method to select optimum grinding conditions such as grinding depth of cut, feed rate of work, dressing depth of cut and feed rate of dressing considering dimensional accuracy, surface roughness and efficiency (grinding volume per unit time). Experimental data to deduce characteristic curves for system ranges were obtained using the experimental design method. Experimental results show that the grinding conditions selected by this system were superior to those selected by an expert operator (ten years experience) from the point of three evaluation items above mentioned.

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This paper deals with a new method to develop optimum conceptual layout drawings of cavities for three-plate family molds. First, it summarizes the necessary knowledge for working out conceptual layout drawings of mold cavities based on the data gathered from interviews with mold designers. Then the paper proposes a new method of determining an optimum conceptual layout drawing of cavities based on shapes of cavities represented by a two-dimensional geometric model, shapes of devices for processing undercuts represented by the model, and the obtained knowledge. This method first decides on a desirable number of runners by dividing multiple cavities into proper groups and then finds the optimum conceptual layout drawing of the cavities as a solution of a nonlinear programming problem. For this purpose, an optimum solution search algorithm using the instantaneous center of rotation was developed to solve the nonlinear programming problem efficiently. Finally, the paper describes successful efforts to verify the usefulness of the proposed method through a case study.

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A split tool dynamometer was employed to investigate friction characteristics at the tool-chip interface. Compared to a standard steel, a calcium treated, resulfurized steel shows lower frictional stress near the chip leaving point and shorter chip contact length. The friction on the rake face can be expressed by a characteristic equation which is similar to that proposed by Shirakashi and Usui.On the other hand, high strain rate compression tests at elevated temperatures were carried out using the Hopkinson bar method to evaluate flow characteristics of the steels. On the basis of the empirical equations thus obtained, a simulation analysis was conducted to examine a correlation between the material characteristics and cutting mechanism. It shows that the difference in friction characteristics mainly causes the chip flow, temperature and cutting forces to change : the free-machining steel brings better machinability, though its flow properties are almost the same as those of the standard steel.

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This paper describes the atomic force based on chemical bonds between diamond and metal (Cu, Fe or Al) surfaces. This atomic force affects the limit of ultra precision machining, therefore, the coefficient of friction on the tool rake face at the time of cutting was measured in vacuum. The measured coefficients of friction of Cu, Fe and Al were 0.18, 0.30 and 0.36, respectively. Also, the interaction force based on atomic force was measured in comparison with the coefficient of friction. The interaction force required to separate the elastic contact between the diamond tip and the flat metal plane was measured with a microelectro-balance in an ultra high vacuum. The interaction energy (interfacial energy) calculated by measured interaction force of Cu, Fe and Al were 1.87, 2.49 and 3.77 J/m², respectively. Thus, the coefficient of friction was strongly correlated with the interaction force, or Cu<Fe<Al. This suggested that the friction of metal cutting was caused by the atomic force based on the chemical bond at the interface. In order to estimate the atomic force theoretically, the electron energy of interface was calculated by the local density of electron states. The local density of states of diamond surfaces adsorbed by metals were calculated by using the recursion method based on semi-empirical tight binding theory. The results of calculation predicted that the values of atomic force were Cu<Fe<Al.

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A new approach to prepare diamond-like carbon film was made by highly accelerating ultra-fine carbon black particles between plane-parallel electrodes held at DC high voltage in 10^-4 Torr, and by making the energetic particles deposit onto the surfaces of electrodes used as substrate. It became clear that amorphous hard carbon films grow only on cathode surface without heat generation and the growth rate depends on the rate of kinetic-energy flux given by the particles striking unit cathode area. The average growth rate of about 10 nm/min was obtained using a 180 mm dia. cathode with relatively low power supply. As for the properties of film prepared, the Vickers hardness value larger than 1 500 kgf/mm² and the semiconductive hopping conduction were observed, which are quite different from carbon black used. These suggest that the graphitic starting material may be transformed into considerably disordered carbon structure due to severe solid-to-solid impact, and a diamond-like carbon film of graphite rich may be formed.

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As machined surface characteristics are greatly affected by a cutting mechanism, a prediction method of the mechanism is required for obtaining the appropriate characteristics. The paper discribes a method for predicting cutting performances of aluminum single crystal in low cutting speed. A flow stress is discussed by slip system theory of single crystal. A single crystal may be considered as a material with orthogonal anisotropy. The change of anisotropy by straining is also introduced through simple shear tests. The friction characteristic equation on tool rake face is also proposed. The simulation analyses of cutting process on aluminum single crystal are finally carried out using FEM calculation including orthogonal anisotropy. The alternations of shear angle, friction angle etc. with each cutting direction for the single crystal are obtaied through the simulation. These analytical results are compared with those of fine cutting experiments which are carried out in SEM.

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This paper presents some experimental results of single crystal ferrite in scratch tests with various shapes of diamond chisels and in grooving tests with diamond wheels.On scratch tests with diamond chisels, there is no crack on the surface of a groove but plastic flow is generated at a small scratch load less than 0.02-0.05 N. The height of plastic flow is as large as the depth of a groove. On the other hand, such small plastic flow, called as burr, as about 0.1 μm high and 1, μm wide, is created on both shoulders of grooves in groove grinding of single crystal ferrite using diamond wheels. The burr height has a strong correlation with the uncut chip thickness which is determined by such factors as wheel speed, table speed, depth of cut and the amplitude of forced vibration of a wheel. For restraining the burr height, keeping the small uncut chip thickness on each cutting edge of grains are recommended.

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This paper deals with the analysis of work regenerative chatter in cylindrical plunge grinding of low stiffness workpiece. The effect of grinding parameters on chatter stability and chatter frequency is discussed in some experiments and a theoretical analysis. The chatter stability is examined experimentally by an angular grinding which is a high efficiency grinding method, and it is analyzed to first approximation by the application of the regenerative chatter theory for usual plunge grinding. Dynamic grinding force due to the relative penetrating velocity of the grinding wheel to the workpiece is considered in this chatter theory. The following conclusions are obtained. (1) To increase the structural stiffness results in low chatter stability with the lower stiffness of the workpiece. (2) The chatter theory for usual plunge grinding does not matter in a practical application to the chatter stability analysis in cylindrical angular grinding of the low stiffness workpiece. (3) Plunge velocity scarcely affects the chatter frequency.

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As electrode feeding mechanisms of conventional electro-discharge machines for micro holes consist of ball screws, gears and motors, they are large. This proposed electro-discharge machine is miniaturized to dimensions of 18×14×68 mm because its electrode feeding mechanism consists of an actuator, which can move by bits, utilizing rapid deformations of piezoelectric elements (Impact Drive Mechanism). Its step is variable and the step of 0.02 μm can be obtained easily. The machining performance of this machine is as good as that of the conventional ones Some applications of the developed electro-discharge machine are proposed.

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