[in Japanese]

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The purpose of this paper is to develop a non-contact 3-D digitizing system using an NC machine tool which can measure and free-form surfaces such as 3-D model shapes for injection molds speedily and accurately. The proposed 3-D digitizing sensor has a major advantage in that the location of a light spot obtained by passing laser light scattered from a target surface through a unique lens system is linearly proportional to the displacement of the surface in optical axis. This sensor, with a measuring range of 20 mm and resolution of 11 μm/pixel, can measure the displacement of a target surface within an accuracy of ±50 μm for a steep inclined surface up to ± 75 degrees without causing a dead angle called the shadow effect. The 3-D digitizing system which can measure 3-D model shapes at high measuring speed of more than 4 m/min is developed, in which the sensor is automatically moved up and down by servomechanism as the light spot to be detected exists always within the measuring range of sensor during the traversing of the NC machine tool. Moreover, the profiles of a 3-D model shape can be observed in real time.

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In this paper, a unit system magnetic abrasive finishing apparatus is newly developed in which five ferrite permanent magnets are used as generating elements of magnetic flux, instead of the conventional finishing apparatus using an electromagnetic coil which is large in size and heavy in weight. This unit system finishing apparatus is very easily installed on the table or the carriage of ordinary machine tools, and is small in size and light in weight. From the experiments, it is confirmed that the finishing performance of this new apparatus matches for that of the conventional apparatus using an electromagnetic coil.

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In the 1st report, the applicability of alumina ceramics (Al₂O₃) to ball screws was studied by rolling fatigue life test using the simplified cylindrical model of ball screws. In this report, the applicability of silicon nitride (Si₃N₄) and Sialon (SiAlON) ceramics was also studied by the same method. It was clarified by the test that the surface roughness of both materials had influence on the life and the basic dynamic capacities of both materials were 10% of that of bearing steel (SUJ 2) when the test pieces had good surfaces. SEM observation made it clear that the fracture occurred at the outskirts of ceramics pores in the same process as the fracture of the alumina. As a result, the applicability order of 3 ceramics are the silicon nitride, Sialon and alumina.

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A method representing crystallographic orientation of single crystal diamond tool on the Mercator map is proposed. Properties of single crystal diamond tools have been studied. Experimental results of cutting by diamond tools oriented various crystallographic direction lead to the following conclusions. On the cutting aluminum alloy, the minimum cutting forces and the minimum coefficient of friction between the tool-chip interface take place on the tool whose rake face is identified with the {110} plane and whose inverse direction of cutting edge is coincided with <100> direction. To the tool equipped with low frictional rake face, the chip flows straight and adheres lightly to the face. On the other hand, to the high frictional one, the chip curves and adheres heavily.

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This paper explains how the temperature of Si wafers during polishing affects their flatness after polishing. During the polishing operation, the temperature distribution of the wafer was measured using thermistor sensors (0.1 K accuracy) attached to the wafer opposite the surface being polished. It is made clear that this distribution is affected by the pouring method and temperature of the polishing reagent. The temperature near the center of the Si wafer during polishing is about 1.0 K higher than that of the surrounding area. As a result, chemical action is activated, increasing the stock removal rate at the center, and the polishing wafer is out of flat by 0.6-1.2μm in a concave direction.

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A slicing technology based on new concept of Multi-Wire-Saw has been developed for high precision and efficiency. This technology is composed of new driving system and new temperature control system. First, to achieve high efficiency, unidirectional wire driving system was adopted. In this system, a very long wire is driven in only one direction at high speed (max 600 m/min), while a wire is driven reciprocally in coventional Multi-Wire-Saw. Second, to achieve high slicing precision, temperature control system has been newly developed, in which cooling oil is circulated to keep the temperature constant on the grooved roller surface during slicing. This system has made it possible to stabilize positions of wire and to minimize wafer bow caused by thermal expansion of grooved rollers during slicing.

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Depth of reluctant uncut and deformed part have been measured by original methods in unidirectional prepreg cutting. Depth of reluctant uncut that significantly controls accuracy of dimension were attributed to elastic recovery of the machined surface layer. Depth of reluctant uncut could be determined by measuring a step between pre-cut surface and newly generated surface using an electric micrometer. Deformed part that corresponds damaged layer of metal machined surface could be observed by an optical microscope with Nomarsk i differential interference contrasts. Measurement results indicated that both values were markedly affected by rake angles, fiber angles, and depth of cut. Tangential and normal cutting forces were remarkably dependent on depth of deformed part and reluctant uncut respectively.

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The objective of this study is to identify the dimensional machining error due to recovery of local elastic deformation of work material at the tool-work contact point and to clarify the parameters to influence upon the elastic deformation, experimentally and theoretically. By applying linear regression analysis to the relation between given depth of cut and actual depth of cut such a very small quantity as elastic deformation of work material at the tool-work contact point can be quantified. In machining aluminum, delrin, nylon 66 and polystyrene, the error due to local elastic deformation of work material is an order of micronmeter, which is serious for high-precision machining. The smaller the elastic constant of work material, the larger the error is, this being verified also theoretically. Also, the experiments have disclosed that the dimensional error due to local elastic deformation of work material increases in proportion to the radius of cutting edge roundness, this being verified theoretically, too.

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This paper deals with the centerless grinding of complex shaped workpieces which have a through hole or a rectangular groove on the cylindrical surface of them. The shape of roundness of both workpieces centerless ground are analyzed into number of lobes and amplitudes of the lobes. This result showed that the number of lobes and the amplitude of the lobes are determined both by the periodic variations of grinding width on the cylindrical surface of workpiece, and by geometrical work rounding mechanism which is strongly correlated with the center height of a workpiece. And it is also appeared that even number of lobes tends to be formed at the through holed workpiece, and odd number of lobes tends to be formed at the rectangular grooved workpiece. Improving the out-of-roundness is performed by setting the center height lower for the through holed workpiece or setting the center height higher for the rectangular grooved workpiece in centerless grinding.

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Main cutting edge configuration of flat rake face drills is geometrically analyzed and compared with the geometry of a conventional twist drill. Applying the cutting model and energy method proposed in previous papers, in which the condition of side-curl of chip is considered, to the case of flat rake face drill, chip formation relating radius of side-curl of the chip and shear angle distribution along the cutting edge, and cutting torque and thrust force can be predicted in both formation processes of a conical-helical chip and a long-pitch helical chip. The differences of torque and thrust force respectively derived from theoretical basis between both chip formation processes are small and the result is experimentally confirmed. The torque and thrust force of the conventional twist drill having a 32° helix angle are almost equal to those of flat rake face drill with rake angle α₁=15-20° which is specified in grinding the rake face of the drill.

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This paper deals with a formation mechanism of the side burr on the workpiece end by using a finite element method and an experimental method. In the calculation, grinding temperature and cutting force in the contact zone are considered. Therefore, the thermal and mechanical stress distribution of the workpiece end are derived. The grinding is carried out to clarify the effect of work speeds, depth of cut and number of grinding passes on the burr size. The main results obtained are as follows : (1) The grinding temperature causes a plastic deformation on a workpiece-surface layer, while it is not enough to produce a macroscopic plastic flow. (2) The plastic flow is produced mainly by the grinding force. (3) In the vicinity of the workpiece end, the plastic-flow layer is expanded at an angle of 34-42° with respect to the grinding direction. The results show a similar tendency with experimental ones.

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When one will measure the precision profiles of super smooth surfaces using an optical interferometer, a perfect-flat reference mirror should be used. However, it is impossible to obtain such a mirror. For the case using a stylus method, a perfectly-straight-moving slide table should be used. It is impossible to obtain that table too. In this paper, We propose the optical precision profiling method which does not need a perfect-flat plane. This method is developed on the optical skid method previously reported (the 1st report). For the surface data obtained using the optical skid method, the amplitude of low spatial-frequency components were attenuated noticeably and the data were used as the roughness profiles. This paper will make it clear that : (1) One can theoretically calculate the exact attenuation rate of frequency component from the positions and the sizes of the photo-detectors used in the sensor head of the optical skid method. (2) One can completely retrieve the surface profile by the digital filtering using the calculated attenuation rate. In an experiment, a profile of a step height standard is retrieved using the method mentioned above. And a waviness profile of a mirror obtained using this method is compared with the profile measured using Talystep.

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This paper discusses an ultra -precision wafer positioning technique, especially applicable to improve the alignment accuracy of X-ray lithography systems. A unique six axis micromotion mechanism using high resolution piezoelectric actuators has been developed, and its kinematic characteristics and micro-positioning performance have been thoroughly investigated. As to the structure of the mechanism, a wafer chuck is supported by six links comprised of piezoelectric actuator and spherical metal joints at both ends, which enable the chuck to move with respect to six degrees of freedom by expanding and contracting the links. To improve design versatility of position control systems, a software (digital) servo control featuring variable voltage integration has been introduced. The experimental results indicate that this technique is capable of positioning the wafer with a resolution less than 0.01μm.

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This paper deals with an analysis of effects of sampling period to a digital servo system from a standing point of a frequency response and a transient characteristics. The servo system to be analyzed here has a scheme of a standard second-order continuous data system, whose characteristics are specified by a proportional gain and a time constant. The main control process of proportional operation is supposed to be realized by a digital data system acting in a sampling period with an one-sample delay. At first, all parameters of the system are normalized with respect to the time constant. Then, the relationships between the normalized sampling period and the normalized proportional gain (and also the normalized cut-off frequency) defined by a phase margin are shown by charts. Moreover, the same relationships defined by a critical damping condition of a transient response are described. Furthermore, the digital servo system whose one-sample delay action could be compensated is also analyzed.

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In the present paper, about planar 9-link conveying machine which is not discussed with consideration of layer arrangements of moving links, conditions which determine the minimum number of layers required to construct the conveying machine are formulated. Based on the above results, link profiles avoided mutual interferences among moving links are determined with consideration of the relative location of links on the same layer during a cycle of motion. In order to discuss the influence of profiles and elastic deformations of links and the differences of layer arrangements of moving links upon the link displacements from the ideal planes of motion of links, the dynamic characteristics of the machine are investigated experimentally.

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In order to realize the most accurate positioning in bearing systems, two methods have been mainly proposed. One is holding the table in a constant position by using a controlled piezoelectric actuator which reacts to the change of gas film thickness. The other is by changing the flow rate through restrictors. This paper describes these controlled shaft trangent response characteristics under impulse forces in hydrostatic circular thrust gas bearings with a central pocket. Following conclusions are obtained : (1) The shaft convergent characteristics are good in both methods if there is no phase-lag in control systems, etc. (2) The shaft under self-excited vibrations can be better stabilized by the latter method. (3) The phase-lag in control systems in the former method, greatly affecting the shaft convergence characteristics, should be less than about 1/50 of a natural period time of gas bearing systems.

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This paper describes a new noncontact optical method to measure a profile of a reflective object. One of the methods to reduce affects of disturbance light and changes of the object surface is to use the controllable active lighting system as the reference light source. The digital optical devices, an LED array and a plasma display are used in this method as an active light system that can be controlled by the computer system. The form of the reflecting surface that has large and complex curvatures is difficult to measure by image processing, because of difficulty to recognize the relations between lights and reflecting images. This method recognizes easily the relations between lights and reflecting images and reduced affects from disturbance light and changes of surfaces. The star form reflecting object of diameter about 100mm that had large and complex curvatures was measured by this system.

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In high-precision lapping process, it is required to measure accurately the surface shape of the lapping plate because the flatness of the workpiece such as Si-wafer is affected significantly by the surface shape of the lapping plate. This paper describes the flatness measuring system which is composed of a measuring bar equipped with several displacement sensors and a microcomputer. The measuring bar is set above the rotating lapping plate and then signals obtained by the sensors are delivered to the microcomputer to process and display the flatness of the surface as the 3-D image. In this case, unavoidable error motion of rotating axis and inclined plane error should be occurred. To avoid these errors, a geometrical method in which the sensors are set at the intersections of the measuring lines is proposed. An experimental result shows that the measuring accuracy approximates to the resolution of the sensors. It is recognized that this measuring method is useful for the surface analysis of the lapping plate.

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