[in Japanese]

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[in Japanese]

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This paper describes the initial grasping process of a new vibration gripper. The gripper can handle an object of unknown weight and unknown surface conditions with its most suitable grasping force. The gripper is constructed so as to have two parallel fingers. Each finger consists of a structural finger, a main spring, a grasping finger, an absorber spring, and an oscillator block. These parts in each finger compose a series mass-spring system having two degrees of freedom. An external force with the natural frequency of the system composed by the oscillator block and the absorber spring is operated on one of grasping fingers. In the initial grasping process, the gripper can grasp the object in the most suitable grasping condition in which the grasping force is regulated at the optimum value, and both the grasping fingers and the object are stabilized in a stationary condition because their vibrations are absorbed by dynamic dampers composed of the oscillator block and the absorber spring. In this paper, the initial grasping process divided into five steps is described, and the most suitable grasping condition is analyzed theoretically and is confirmed by experiment.

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A small interferometer for the use of precise scanning electron microscopy has been developed. Optical components and a piezo-driven mechanical scanner are integrated on a small disk of 130mm in diameter. the device is small enough to be installed in the vacuum chamber of regular scanning electron microscopes (SEMs), and enables absolute linewidth niasurements based on laser wavelength. The performance of the system is evaluated and compared to those of an absolute linewidth measurement system we have developed before. The results show good agreement of a couple of nanometers in the sub-micrometer linewidth measurements. This system can be applied to various types of microscopes such as scanning probing microscopes (SPMs). and useful as an important device for calibration service in the precise micro-length measurement.

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Static force to an actuator is switched by a microcomputer in which displacement of an impacter is compared with on-off positions stored and decides on-off timing of the excitation. The switching causes self-excited impact vibration by rectangular pulsive force train. The paper presents estimation of drive condition for the steady-state motion by energy supplied dissipation per unity time, the power dissipation, for comparison of the motions having a different period. The optimum bipolar drive condition by the power estimation is available in the case that both the switch on position for the pull up force and the switch off position for the pull down force agree with impact position, in addition that the pull down force is acted in the moment of cut of the pull up force. In other words, the power is minimized by bang-bang drive. In the case of unipolar drive by the pull down force, there is not the practical condition, because the duration of force decreases to infinity and the force level increases to infinity. Hence it is reasonable that the force level is selected as high as possible and its corresponding duration of the pull down force is determined.

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A new calibration method which needs no accurate reference instrument is proposed to calibrate precision angle sensors. In the first step of the method, the mean sensitivity of an angle sensor is determined by applying the self-calibration principle of a rotary scale. For this calibration, a special system has been constructed with two coaxial rotary tables driven by stepping motors individually. In the next step, the linearity error of a pair angle sensors are determined by applying the self-calibration principle which has been developed for the displacement sensors. Using this method, the linearity error of the calibration curve can be determined within an uncertainty limit, which is given by the resolution of the angle sensors, electric noise and thermal drift of the system. Angle sensors using critical angle prism have been developed which have measuring range 1296 s (arc) and resolution of 0.05 s (are). These angle sensors have been calibrated by the proposed method. It was found that the repeatability error of the calibrated mean sensitivity was less then 0.02%, and the repeatability error of the calibrated linearity error was about 0.1 s (arc).

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The Clothoid is a planar curve, of which curvature is proportional to the length of the curve measured from the origin of the curve. In this paper a method of clothoidal interpolation by “tangent method” which can realize continuity of curvature is described. By applying the method smoother interpolation curve is obtained between freely given 2-dimensional point series. The criteria of continuous curvature is formulated by slightly correcting the tangents of given pass points. The algorithm of the method is mentioned and some results are shown.

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A circle cutting method for plate glass is proposed. Using this method, plate glass can be cut into many small circle plates almost simultaneously, irrespective of the number of plate glass desired cut. This method is called “Elastic Working” which aggressively exploits the progress of natural cracks occurring at the fracture of brittle materials. The characteristics of this method are as follows. (1) The plate glass can be cut almost without generating noise, waste or dust. (2) The cut section is perpendicular to the face of the plate glass. (3) The energy required to cut is minimal and the cutting time is very short. (4) The ceramic plate can also be cut as well as the plate glass.

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Lenses, mirrors and mold dies of high accuracy require local uniform grinding in micron scale for their best quality. A new type of magnetic fluid grinding is introduced for this purpose. The grinding system consists of actuators, a magnetic ball as a tool, non-magnetic workpiece (borosilicate glass), non-magnetic abrasive grains, a segment of magnet and magnetic fluid. The effect of magnetic field on grinding properties is carefully observed. It is concluded that the local uniform grinding in micron scale is possible by this method, which means that the combination of magnetic fluid and magnetic field can provide unique micro grinding.

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The experiments described in this paper are to obtain basic data needed for forming segmentalized chips and to examine the effectiveness of the handling of these chips in comparison to the chips formed by conventional drilling. The segmentalization that a continuous chip is divided into small parts per one revolution of drill was carried out by an exciting device, developed in this study, with oscillation superimposed to the feed of drilling. On the formation of three-divided chips in the work material of steel (SS 41) occurred chipping on main cutting edges in the neighborhood of chisel edge while in the case of the work of aluminum (A 1050) it did not occur. This chipping is caused by iterative motion of the cutting edges. The estimation of the handling was taken as a measure of the weight of the chips cumulated near the drilled hole and their bulk. The chips are cumulated almost near the hole in this drilling and their bulk became 1/11 in steel and 1/5 in aluminum of the chips formed by conventional drilling, respectively.

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In surface grinding of steel, the temperature in the surface layer of the workpiece and the temperature of cutting grains on wheel surface are measured by means of a new method, in which an optical fiber accepts the infrared flux radiated from the object and transmits it to an infrared detector InAs cell. This I.R.P. is suitable for measuring the temperature of a very small object whose temperature changes rapidly. The influence of the physical properties of workpiece and grinding conditions on the grinding temperature and the thermal partition coefficient are investigated. A carbon steel, a stainless steel and a cast iron are used as work materials. The thermal partition coefficients obtained by experimental results are compared with those obtained theoretically.

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Reports of study for welded bellows with cracks have apparently not been published to date. The purpose of this investigation is to understand the relationship between the state of stress of welded bellows with micro cracks and the fatigue life. Stresses of welded bellows with cracks were calculated for several different crack lengths by finite element method (FEM), and lives of bellows with cracks were examined by fatigue test. The fatigue life, i. e. the number of cycles to failure was arranged against the remaining wall thickness measured after test instead of the crack length. As a result, it was found that there is a regular relationship between the stress amplitude of peak stress calculated by FEM and the fatigue life of bellows. And then, it was shown that the life of bellows becomes longer than the life estimated using a theoretical S-N curve calculated by Manson's method. Stress intensity factor range (ΔK) and crack propagation rate (da/dN) were also calculated using the results of stress analysis by FEM and fatigue test. The relationship between ΔK and da/dN obtained was almost coincident with the earlier result of fatigue crack growth test of Inconel 718 in the region of da/dN >1.5 × 10^-6mm/cycle, and the propriety of the present results was confirmed.

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An apparatus for fabricating diamond powders by means of arc-discharge plasma jet CVD (chemical vapor deposition) method was developed with an attachment for collecting the fabricated powders. It was found that a nickel substrate is the best material for fabrication and a scratching brush made of piano wire of diameter 0.2mm is fit for collecting diamond powders. With this apparatus, diamond powders of diameter 15μm can be fabricated in 5 minutes, and the collecting ratio is 60%, that is 12.4mg per hour.

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This report aims to clear experimentally the influence of polishing pressure, polishing speed and the content of Al₂O₃ abrasives included in polishing fluid on the removal rate and the slight undulation of the NiP plated magnetic disk substrate. The substrate surface is examined by measuring the slight undulation and the surface roughness, which are measured on the substrate surface of 4 mm length with WYKO and 50 μm length with Talystep, respectively. The polishing experiments are carried out with a marketing machine with some reconstructions. In case of the soft type polisher, the removal rate increases with the increases of polishing pressure, polishing speed and the content of Al₂O₃ abrasives. The terminal surface roughness becomes better for lower polishing pressure. Polishing speed and the content of Al₂O₃ abrasives have little influence on the terminal surface roughness. The terminal slight undulation becomes better for lower polishing pressure and the less content of Al₂O₃ abrasives, and is little influenced by polishing speed. In case of the hard type polisher, on the other hand, the removal rate increases little or decreases with the increase of polishing speed over a critical polishing speed at low pressure because the floating force of polishing fluid decreases the actual polishing pressure. The relationship between the polishing conditions and the slight undulation for the hard type polisher, however, is similar to the soft type polisher. The best slight undulation obtained in the experiment is about 4 nm (P-V value).

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Frictional characteristics of ground surface of aramid fiber reinforced rubber (AFRR), which is one of the advanced composite materials for transmission belt, are dominated by grinding conditions, and form and size of aramid fibers which aren't removed projecting on the surface of matrix rubber in grinding. In this paper, the coefficient of static friction is analytically described based on Hertz's theory of elastic contact in terms of arrangement of aramid fiber in matrix rubber, occupying ratio of fiber on contact surface of AFRR with pulley and so on, and the validity of this analysis is also discussed by comparing the theoretical coefficient with the measured one. It is pointed out that the coefficient of static friction on ground surface of AFRR can be predicted by fiber diameter, fiber content, length of projecting fiber, width of fiber end and coefficient of static friction of matrix rubber and aramid fiber. Though the coefficient of static friction on ground surface of AFRR is analyzed for four ideal conditions of projecting fiber, the measured coefficient agrees well with the analyzed one for the case that fibers are uniformly arranged in hexagonal form and ground in the direction of a central diagonal of this hexagonal fiber arrangement. Furthermore, the validity of this analysis is shown by investigating effects of pressure on contact conditions between pulley and ground surface of AFRR.

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Local area polishing has been done by using a newly-developed fine pressure controlling machine. Fine pressure yielded by repulsive magnetic force between an electromagnet and permanent one, has proved to be excellent polishing performance on the optical glass. Polishing rate at any point on the workpiece should depend on the shape of a pad as well as the polishing condition, such as relative motion of polishing pad and workpiece. In the present study focusing on the reduction of surface waviness in the order of nanometer, the effects of pad shape on the polishing characteristics are experimentally and analytically examined. It is found that the profile of polished surface can be controlled by the shape of the polishing pad, and that the developed technique is very effective in the modification of the surface profile in nanometer scale.

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The corner dullness which deteriorates the corner shapes is often generated at the ends of the ground machine parts. The aim of this study is to find the measures for diminishing the corner dullness under one-pass-plunge grinding. Through the theoretical study, which is based on a model considering the wheel to workpiece relative displacement, effects of the grinding condition on the shape of the dullness are clarified. Some of the factors have opposite effect on the height of the dullness from its length and they also have contrary effect on the size of the exit-dullness to the entrance. In order to diminish the height of the exit-dullness, which usually have significant effect on deteriorating the corner shape, it is important to decrease the wheel depth setting, table speed, and wheel radius and to increase the wheel speed. However, the chattering tends to occur around the starting point of the grinding pass when utilizing the grinding wheel of small radius or minute down-feed. When a backup material is set beside the workpiece during the grinding process, the size of the dullness can be effectively diminished.

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This study proposes a non-manifold shell operation which uniformly manipulates solids and surfaces as shells, in order to enable designers to realize free generation of shapes. This report first describes definitions of shell and non-manifold shell operations and presents some examples of them. Next, it proposes direct cancel operations for the shell operations to modify generated shapes. The non-manifold shell operation uniformly processes a regularized set operation, an extraction of solids by automatically detecting closed shells from a complex shell which is combination of solids and/or surfaces. Its direct cancel operation is an operation which recovers a shape, independently from a sequence of operations, to one before the designated operation was executed. This cancel operation is applied to efficient parametric design by recovering the shape after changes of parameters.

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It is important to generate and evaluate assembly sequences in product design stages for reducing manufacturing costs. This paper proposes a method for generating the assembly sequences efficiently. In the method, the problems of generating the assembly sequences are decomposed into subproblems, and the decompositions are represented as AND/OR graphs. To generate the sequences, an algorithm for searching the AND/OR graphs, which are reduced by using heuristics, is developed. This algorithm is efficient especially to generate the assembly sequences for the design objects got by modifying the original ones whose assembly sequences have ever been generated. The efficient generation of assembly sequences is achieved by using the assembly sequences of the original design objects. Based on the method, a system is developed, and an example is given by using the system to demonstrate the effectiveness of the method.

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