[in Japanese]

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[in Japanese]

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An automated library system has been developed for the complete operator reduction in the large computer systems, adopting the magnetic tape cassette system capable of high speed information transfer and high density recording. The media handling unit, the main part in this system, has the following technical features: (1) Highly reliable handling by means of wearless cartridge mounting and digital-controlled cartridge transport with dual mechanisms. (2) Motion control for earthquake protection and autonomous motion judging from the circumstance change. (3) Automatic maintenance with cleaning tapes and accident prediction with a statistical information of component wear.

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This study is an approach to the automatic generation of dimensioning data that define solid model fully but not redundantly. The data are represented as the distance among geometric elements which compose 3 d model and the dimensioning procedure is formulated as a frame problem of AI. In the problem, geometric element data, which are explicitly extracted from the 3d model, are used as state description and their flags are used to examine the sufficiency or redundancy of dimensioning. The dimensioning is conducted by reasoning based on rules stored in the knowledge source of blackboard type expert system. Rules consist of three levels. These are: (1) overall dimensioning strategy rules that depend on the machining sequence of the part, (2) dimensioning rules that depend on the geometric feature of the part, (3) rules that generate dimensioning data while changing or examining the flag state of the part, and they are formulated so that the upper level rules invoke lower level rules. This hierarchical structure makes rule description more flexible. One example of experiments is shown and the method proposed is concluded to work properly.

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The use of a new material is a hopeful strategy for breaking through the barrier of improving the product performance and/or the lowering of the product manufacturing cost. This paper proposes a methodology for decision making of a material used in machine structures from the standpoint of structural dynamics. First, purposes for use of new materials and evaluative parameters for decision making of material choice are described, and fundamental rules and knowledge for decision making are established. Then, based on those evaluative parameters and rules, general decision making procedures for material choice are constructed. Finally, for model cases of purposes for use of new materials, detailed decision making procedures are explained using also some numerical examples.

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It is considered that contraction deformation of bolt is one of the causes of loosening in a boltnut unit. In this paper, radial deformation of bolt shank which consists of the mating thread portion and the other, is examined analytically and experimentally. First, a method is proposed to analyze the deformation of the bolt shank in a bolt-nut unit under the axial load, and the radial deformation of bolts shanks is calculated by this method. Second, the validity of the numerical analysis is confirmed by some experiments with strain gauges. As a result, it is revealed that mating thread of bolt shank contracts in a radial direction by the force acting on mating thread ridges and Poisson's ratio under tensile load. Especially, its contraction deformation is large at the part of bearing surface for concentration of load, while the rest of bolt shank contracts almost uniformly with Poisson's ratio.

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For the deformation of an isotropic thick plate, a refined theory to derive two-dimensional approximate equations with any desired accuracy is proposed. Especially, for a plate under any distributed load at the surfaces, equations for extensional deformation as well as flexural deflection in the general n-th order approximation are derived from fundamental equations. Approximate equations presented are solved for a plate subjected to a sinusoidally distributed load at the upper surface, and the results are compared with the exact solution and with those derived from several approximate theories hitherto obtained through numerical calculation. It is shown that approximate equations presented in this paper have the following properties: (1) With increasing the order of approximation, the solution of approximate equation improves in accuracy and approaches the exact solution. (2) Approximate solution of stress satisfies the boundary conditions at the surfaces of the plate. (3) The accuracy of the approximate solution decreases monotonically with increasing the thickness of the plate. (4) The effect of Poisson's ratio on the accuracy of the solution is small and can be neglected for practical purposes.

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A pneumatic servo-system which is composed of a cylinder installed vertically, double electro-pneumatic proportional control valves and feedback equipments has been developed for a Z axis actuator of a robot for assembly. Optimal control method is applied to the system in order to accomplish accurate positioning and force control of the cylinder. Optimal control inputs for piston position and force have been computed by a microcomputer using optimal feedback coefficients which are derived from Riccati's equations so as to minimize settling time and overshoot of the step response in positioning and force control of the piston. In the piston control, the positioning repeatability of ±0.5 mm for the optimal control and ±0.2 mm for the optimal control with an integral compensator is achieved. On the other hand, the repeatability of within ±1% of an assigned force is obtained in the force control.

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There is a singular point in the movement, whose rectilinear displacement remains constant independent of the loading position of a mass. The point is located at the geometrical center of two springs. It is, however, clarified in this paper that strictly analyzing displacement of springs by using the theory of beam subject to combined loads, the point deviates from the center. The results reported are; (1) The deviation of the point is expressed as, x_p/l₀=-(3/175)(δy₀/t₀)² (s/l₀), where l₀, t₀; half length and thickness of leaf spring, s; loading position of the mass, measured from the center, and δy₀; displacement of the point at s=0, equivalent to the true value of the mass. (2) Letting δy, be displacement of an arbitrary point x, the ratio, (δy-δy₀)/δy₀ means the error rate of the mass to be weighed. The ratio is written as, (δy-δy₀)/δy₀_??_(t₀/L₀)²(s/l₀)(x/l₀), where L₀; height between two springs. Since t₀/L₀ is, in general, very small, as small values of s/l₀ and x/l₀ as possible contribute to the design of a balance with high accuracy.

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The purpose of this investigation is an invention of theory and technics on surface roughness≈0, roundness≈0 and cylindricity≈0 machining. This is analyzed according to the principle of making a precise circle. In this study, the method of precision cylindrical machining can be created by combining the insensitive vibration cutting mechanism, (40 Hz+30 kHz) superposition superfinishing, the main spindle system with the air bearing and the carriage system with the pneumatic floating slideway. The concrete methods are as follows: In the first process, the work which is chucked on the main spindle with air bearing is machined as acting a continuously and systematically pulsating cutting force by the ultrasonic vibration cutting mechanism. In the following process, the work is finished by the newly developed (40 Hz+30 kHz) superposition superfinishing device. Key points of the technics are as follows: The one is a contrivance of the carriage system with the pneumatic floating slideway for making high straightness, and rigidity. The other is a contrivance for making accurate motions and no reaction of the (40 Hz+30 kHz) superposition superfinishing device. After all, to actualize machining surface roughness of 0.05-0.15 μmR_max, roundness of 0.02-0.1 μm, cylindricity of≈0-0.5μm/50 mm are succeeded in work material of aluminum alloy, brass, carbon steel, stainless steel and hardened steel (HRC 35, 39). Therefore, it is found that the super precision cylindrical machining can be realized by means of this new machining process and its lathe.

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A crack extension problem based on the fracture mechanics is solved to estimate the length of downward extension of a crack and the upper limit of depth of cut preventing its extension in orthogonal cutting of ceramics. To solve the problem evidently in conjection with mechanical properties of the work, the stress field of the expansion of a cylindrical tube is successfully applied to the elasto-plastic tensile stress field in the work by the tool progress. It is shown that the length of the crack extension is uniquely determined by the combination among the depth of cut, the fracture toughness and the yield strength. The upper limit of depth of cut is found to be proportional with square of the ratio of the fracture toughness for micro crack-to-the yield strength. The estimated value of the upper limit of depth of cut coincides approximately with that of experiment for alumina ceramics and soda-lime glass.

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A 30 W CO₂ laser was used to perform localized etching on Si and Si₃N₄ coated with an aqueous KOH solution. According to Fourier transform infrared reflection absorption spectrometry, the surface of Si coated with an aqueous KOH solution is oxidized by CO₂ laser beam irradiation, but the spectrum is different from one oxidized without chemical enhancement by KOH. Surface photo voltages which depend on the energy level and the density of surface electron states were measured in order to characterize the oxidized Si surfaces formed with chemical enhancement by KOH. Local density of electron states of model oxidized Si surface structures were calculated using the recursion method and semi-empirical tight-binding theory, and the mechanism of the etching process was investigated. The following results were obtained. The oxidized surface layer has a higher density of defects than one formed without enhancement by KOH. Accordingly, the atomic binding energy in the oxidized layer is decreased, and low power laser etching can be possible.

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In this paper propose is a model with which grinding results can quantitatively be given from the viewpoint of cooling and lubricant actions of water soluble type grinding fluids. Experimental results are compared with calculated results by using this model. Main conclusions are as follows: (1) Cooling action is measured as heat transfer rate of grinding fluids and lubricant action is measured as coefficient of lubricant on the grinding wheel surface. (2) Dimensionless grinding results G_r* are given by: G_r*=μ_*^α·h_*^-β, where h_* and μ_* are dimensionless cooling and lubricant moduli defined from heat transfer rate and coefficient of lubricant. (3) Close agreements are obtained between experimental and calculated values of workpiece surface temperature and grinding forces.

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In the 1st report it was demonstrated that the belag on the tool surface of carbide tool improved the machinability when cutting resulfurized steels at high cutting speed. Since ceramic tool mainly consists of alumina, it may be estimated that the forming condition and the effect of belag are not similar in cutting with carbide tool. The purposes of this report are to clarify the wear characteristics of ceramic tool and build up a relationship model between the crater wear and the contents of Al, Si and O in the work material. Main results obtained are as follows. (1) The protective layer was not formed when cutting rimmed steels or extremely low oxygen content killed steels, in such case the crater wear of ceramic tool in machining resulfurized steels is larger than that of regular steels. (2) Resulfurized steels containing high level oxygen and proper contents of Al and Si form a stable layer on the tool surface and it reduces the wear of ceramic tool. (3) The wear of ceramic tool in cutting FeSi deoxidized resulfurized steels is serious, and in some case the crater depth is larger than that of carbide tool.

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Microcutting mechanism of amorphous metals is elucidated by means of in-situ SEM observation of chip formation process. Orthogonal microcutting tests are conducted on rapidly quenched Fe-base amorphous alloys, using diamond tools with selected rake angles. The depth of cut is employed in the range of 0.5 to 15 μm. The amorphous metals produce so-called card model type chip exhibiting lamellar slip structure, which has been formed due to periodical occurrence of homogeneous plastic deformation in the primary deformation zone and following catastrophic shear along the localized band. The lamellar slip spacing is found to be proportional to the depth of cut. The size effect on the specific cutting force is not obvious. It is also found that the shear stress along the shear zone is almost independent of the depth of cut, the normal stress, the shear strain and the strain rate. These characteristic features being different from conventional crystalline metals are discussed in terms of inherent deformation properties to the amorphous metals.

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