A method of the formation of grooves and pre-formatted pits on a glass substrate for a magneto-optical disk by contact printing is described. Up to now, a laser cutting method, whereby grooves and pre-formatted pits are formed with a focussed Ar-laser, has been used, and it needs over thirty minutes to expose a disk. But by using a contact printing method, we succeeded in the exposure of a disk for fifteen seconds, thus a mass production of the glass substrate for the magnetooptical disk with high quality and high reliability was made possible.

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This paper describes a method of obtaining a surface region of triangular shape surrounded by usual regular surface derived from a spline net. The element patch is of degree two and the connection of patches is C¹. Each patch is defined by Bézier control points. The surrounding region is defined by spline net of degree two with arbitrary knot distance ratios. At first we introduce a closed surface with minimum number of usual Bézier patches of degree two to show an application of the method and its quality of the connection. Then we treat rounding of a convex region connected with a regular spline surface of degree two with the equal knot distance ratios. From disposition of control points of the surrounding spline net, we give the locations of Bézier control points of the central three patches which connect with each other as well as with the surrounding patches in C¹. Then the method is extended to a case of arbitrary knot distance ratios. Examples are also shown. Because of practical uses, we restricted the connection to the lowest degree curved surfaces, the method is applicable to the higher degree patches as well in C¹ connection.

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There is an ideal point with constant translational displacement in the parallel spring movement comprised of the springs which are symmetric with respect to an axis passing through its midpoint. Compared with the leaf springs, the circular springs can be, from the view point of machinability, made easily with high accuracy, because only boring is needed. Authors studied the effect of the dimensional error of the minimum thickness of the springs on the error rate of displacement of the moment. The paper may be summarized as follows ; (1) Around fifty percent of the dimensional error of the minimum thickness contributes to the error rate of the displacement. This leads directly to the error of mass to be measured by the movement as balance, (2) There exists no difference in the effects of the dimensional errors on the error rate of displacement, between two springs of the upper or lower side, (3) Owing to the mutual compensation, the dimensional errors of the upper and lower springs brought by boring a circular hole through a blank cause no the error rate of displacement, and (4) the existence of the reinforcing plate attributes to improve the sensitivity of the movement as balance and reduce the error rate of displacement.

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This paper deals with heat flow in the spindle head of machine tools and with the methods which decrease thermal displacements of the spindle, especially in Z axis direction. Simple analytical method of heat.flow and temperature rise has been developed for the estimation of the heat load on the spindle. This method was applied to the spindle heads of the model and the actual machining center. The results show that the calculated temperature rises fairly agreed with those measured, and the adaptations of ceramic ball bearings and fins at spindle noze decreased thermal displacements of the spindle.

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Noncontact monitoring equipment for detecting tool failures by optical measurement has been developed for applications to machining centers, turning centers, etc. The equipment consists of : (1) An auto-focusing device for an ITV camera to focus on the failed portions of a tool. (2) A four halogen lamp system for contrasting the failed portions against the normal region. (3) An image processing procedure for extracting failed portions from a composite tool image obtained by lighting the tool from three different axes. (4)An accurate calculating method of quantifying the failures.

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A noncontact optical method for roughness measurement named optical skid method is presented. This method is developed to measure surface roughness accurately under large datum errors introduced by scanning motion, vibration, and thermal deflection. The principle of this method is similar to the typical skid method. Instead of the stylus and the skid, two laser spots with different size (1.2 μm and 400 μm in diameter) are used to detect surface profile simultaneously. The difference between these two signals gives surface roughness information excluding datum, errors. Based on this principle, a very compact sensor using astigmatic focus error detection method has been developed. Experiments with this sensor have shown that it can reduce datum errors by 20 dB and can possibly be used to measure the roughness of a curved surface.

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A method of calculating joint accelerations of a link mechanism is proposed using recursions on Newton-Euler equations. The force and torque vectors exerting from the link i-1 to the link i are expressed by linear terms with respect to linear and angular accelerations vectors of the link i-1. In case of a link of n degrees of freedom (dof), the numbers of additions and multiplications of the proposed method are 536n and 680n, respectively, while those of the methods proposed by Walker and Orin are of the order n³. Numerical experiments show that (1) the computation time of the proposed method becomes less than those of the methods of Walker and Orin when the dof of the link becomes greater than 20, (2) the exact digits of the torque vector of the proposed method is 4-6, while the exact digits of the methods of Walker and Orin are less than those of the proposed method and they decrease as the dof increases.

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Sound is generated in laser beam machining. In the present paper, sound frequency characteristics and material removal rates are obtained using Q-switched YAG laser. The sound was monitored by a microphone with a frequency range of 4Hz-100 kHz. The generated sound frequency range is very wide and the highest frequency could not be measured by the microphone used in the experiment. Although the oscillation frequency of Q-switched laser is 1 kHz, the largest frequency component of the generated sound pressure level exists at 40-50 kHz for all materials used. The sound pressure level is dependent on the volumetric material removal rate ; there is a linear relationship between these values for each material. Furthermore, a microphone for audible sound is applicable to monitoring laser beam machining process because each frequency component has the same tendency for material removal characteristics.

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It is a well-known fact that the position and attitude of an object placed on a plane surface can be precisely adjusted by applying small impacts to its ends. But such a phenomenon has scarcely been applied in automatic control, because an apparatus that can supply appropriately controlled impacts has not been obtained yet. In this research, electromagnetic impulsive force is used for precise positioning. Electromagnetic impulsive force is obtained between a coil and a conductive plate, when an impulsive current flows through the coil. The impulsive current is generated by a discharge circuit. Two different mechanisms are developed for positioning. In the first one, the impulsive force is an external force, and in the other one, the impulsive force is an internal force. The idea has been evaluated through the simulation of motion, and some experiments, and it has been proven that a mass of several kgs can be moved from several nanometers up to several hundred microns by one shot of electric discharge according to the charged energy.

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Tensile moduli and thermal expansion coefficients of newly developed super-drawn polyoxymethylene (POM) fibers were measured by the same laser interferometric measurement system in the temperature range between room temperature and 90°C. The main results of the experiment are summarized as follows : (1) Tensile moduli increase with drawn-ratio, while they decrease after annealing at 160°C. (2) Temperature coefficients of tensile moduli of super-drawn fibers are nearly independent of drawn-ratio and annealing treatment. (3) Thermal expansion coefficients of super-drawn fibers are negative above room temperature. (4) Absolute values of thermal expansion coefficients decrease with drawn-ratio, and annealing also reduces their absolute values. Above results can be qualitatively explained by the mechanical model which assumes the existence of tie molecule chains.

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In a bending test of spring steels, multi-purpose plastics and so on, a fairly large deflection behavior is observed without exceeding the elastic limit of materials. It is of great technological and utilitarian importance to know this characteristic of the engineering materials for various loading modes. This report describes the nonlinear large deflection problem of a thin, flexible beam in a frictional nonsymmetrical three-point bending. Several analytical solutions are presented for investigating prerequisite quantities such as the deflection, arc length, curvature and bending stress. Moreover a large flexural bending test is carried out in order to check the applicability of the proposed theory. The degree of agreement between experimental results and theoretical assessments is satisfactory. Therefore the nonlinear large deflection theory proposed here can be put into practical use.

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In order to make clear the factors affecting brittle fracture of cemented carbide tool, face milling tests were carried out with cemented carbide tip (P 20) and workpieces in which hard (HV = 609) and soft (HV =141) carbon-steel plates were laminated in varied combinations. Except for cutting of the laminated plates of only soft steel, the tool failed by brittle fracture. The probability of tool failure increased (that is, number of cuts up to the occurrence of tip-corner breakage decreased) definitely by locating the hard-steel plate at the engaging side of workpiece, the tool life in this case being as short as that when cutting the hard-steel workpiece only. Further, the tool life became shorter with increasing width of soft plates in the laminated workpiece. Taking into account the result of cutting force measurements, it was suggested that cutting force generated by frank wear in contact with the hard-steel plate greatly influenced brittle fracture of cemented carbide tool.

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Surface hardening by laser or electron beam is due to the rapid heating and cooling rates, which are caused owing to the localized heating produced by high power density beams. The quantity of energy required for hardening is so small that the thermal distortion generated in the workpiece is little. The paper deals with surface hardening of carbon steel by a newly developed small diameter nozzle plasma arc machine which produces power density of about 10⁶ W/cm² at the exit of the nozzle. Carbon steel of S 45C is hardened with the width of about 0.8 mm and depth of about 0.1 mm and Vickers hardness of about 1000 is obtained under working conditions of arc voltage of 43.5V, arc current of 12A and moving speed of workpiece of 3m/min. The hardening capability is the same as that of laser or electron beam. The spreading of plasma arc beam was also discussed. The absorbed power density on the workpiece surface is estimated to be about 10⁴ W/cm², which is obtained from heat conduction theory and experimental width of hardened region.

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Cutting mechanism of CFRP(Carbon Fiber Reinforced Plastics) have been studied. Unidirectional prepreg were adopted to investigate effects of fiber orientation (fiber angles) and tool rake angles on the chip formation. Direct SEM observation of cutting experiments revealed that CFRP cutting had three types of chip formation: delamination, fiber buckling and fiber cutting type, which were determined by the fiber angles and the tool rake angles. Delamination and fiber buckling type appeared on fiber angle 0 deg. cutting. The other cutting conditions offered fiber cutting type, which had continuous and discontinuous chip formation. Fiber cutting type provided the machined surface with different appearance from the others. A number of the fiber ends appeared on the machined surface. The rugged fiber ends allowed irregularities on the machined surface. Most of the fibers on the machined surface had a few cracks in close vicinity to the ends. Cutting forces were significantly affected by the fiber angles. The fiber angle effects on the tangential force were greater than those on normal force. Fiber angle 15-45° cuttings offered the minimum cutting force on every rake angle in fiber cutting type. In case of chip elimination space angle γ< 30°, difficulties in chip elimination produced extensive irregular morphology surface.

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In center type cylindrical grinding, rotational error motion of workpieces is produced by geometrical errors of the center and center hole, their alignment error, lubricating condition in center holes, etc. In order to improve circularity of the ground workpiece, it is necessary to reduce the error motion. In practice, however, it is difficult to keep the geometrical conditions of the center and center hole ideal. The present paper describes a newly developed method for improving the circularity of ground workpieces in spite of the existence of the geometrical errors of the center and center hole. In this method, at the first stage, workpieces are ground by a conventional grinding method, then, the error motion and the circularity profile of ground surfaces are evaluated by using special in-situ measurement technique developed on the basis of the three-point method. At the next stage, the workpieces are reground, controlling the depth of cut minutely so as to remove convex parts of their circularity profile by elastically deflecting the center in the direction perpendicular to the wheel surface by means of a piezo-actuator.

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This paper presents the experimental investigation on the wear characteristics of CBN wheels in creep feed grinding. The obtained results are as follows : (1) As the wheel depth of cut decreases at a constant stock removal rate, the grinding force per a grain cutting edge f_ts increases almost power functionally and the mechanism of wheel wear changes rapidly from the attrition type to the micro-fracture type when the f_ts value exceeds a critical value f_ts (c). (2) The volumetric wheel wear rate takes a minimum value at the critical condition.

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The mechanisms and the characteristics of a pyrolytic process of halogen-containing gases are investigated theoretically and experimentally. A calculation method of analyzing chemical reactions on solid surfaces is proposed. The dissociation process of Cl₂ and SF₆ gas moleculeon a Si (100) surface is investigated by calculating the local energy of the molecule, and a model of the pyrolytic process is proposed. It is confirmed that the dissociation energy of the molecule decreases due to a specific process on the solid surface which can not operate on the oxidized Si surface, and that the dissociation process of CF₄ gas molecule is promoted by oxygen gas molecule.

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Poor machinability of heat-resistant alloys, especially, in view of tool life has gradually become to be a serious problem in the industry of manufacture. In this study, tool life tests in turning five typical heat-resistant alloys with six promising kinds of tool material have been carried out to investigate adaptability of the tool materials for each work material by assessing the tool life curves and analyzing the manners of tool failure. The test results have revealed that brittle fracture or chipping due to metal adhesion at the cutting edge, which is resulted from high strength and strong adhesiveness of the work materials at high temperatures, is fatal for the tool life, and truly justifiable tool materials for the heat-resistant alloys do not seem to be available in the market at present.

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