This review describes the present status, features and trend of mechanoelectrical technology in information processing machinery, which is called "mechatronics" in Japan. In information processing machinery, such as storage and output devices, the transformation between spatially allocated recording data and time series electrical data is performed by a mechanical motion of a body with mass. The performance of such devices depends on the speed and precision of the mechanical motion. The key mechanism to realize high-speed and precise motion is here generally called "positioning/tracking mechanism"; it is further subdivided into four key mechanisms: the "motion positioning mechanism", "constant speed mechanism", "positioning mechanism" and "tracking mechanism". Their present levels of performance and basic design method are described. Explanation of current important problems and leading research related to these four key mechanisms and mechanical motion is also given. In the evolution of mechatronics in data processing machinery, miniaturization is an essential trend. Since this miniaturization results in a decrease in the signal-to-noise ratio of the mechanical motion, the reduction of uncontrolled vibration modes, friction force and wear is becoming more and more important, as the mechatronics evolves into micromechatronics.

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Many methods which estimate dynamic characteristics have been developed and are now widely used in many fields. Most of those methods use the frequency response function (FRF) as input data. Recently, some new methods based on the maximum likelihood principle which also utilize FRF as input data have been proposed by one of the authors. According to these methods, system parameters are estimated with a least squares principle using the reciprocal of FRF's variance as a weighting function. Therefore, it is necessary to estimate not only the FRF itself, but also the variance of the FRF. In this paper, estimation methods of FRF's variance are presented. Mainly, two kinds of methods are used to estimate the FRF from measured input and output signals: they are the "H₁" and "H_v" estimators. In this paper, the variance is formulated for each estimator.

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This paper deals with the application of dual dynamic absorbers to nuclear piping systems to accomplish a high damping value and reduce seismic response at resonance frequencies. The transfer matrix method is used for design of the dual dynamic absorbers as well as for determination of the optimum mounting location. The effectiveness of the dynamic absorber is demonstrated by suppressing the first three resonance peaks in the 3-dimensional model piping system.

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In order to make vibration analysis an easy and automated task for designers, an interactive vibration-analysis system was developed. The system has the following advantages. (1) The system has a user-friendly interface for graphic input of vibration models which enables users to make figures of vibration models on the display by choosing the vibration-model elements listed in the menus with a pointing device (mouse). (2) The system can perform automatic generation of equations of motion from the graphic input and automatic numerical analysis including eigenvalue analysis and time-history analysis. (3) The system is applicable to extensive models of two-dimensional and three-dimensional vibration of multibody systems which can contain various constraints and nonlinear elements including a friction element, an elastoplastic hysteresis element and nonlinear springs/dampers defined by users. The main part of the system was written in Smalltalk-80 and the part for numerical analysis was written in C.

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A new method of vibration analysis of continuous bodies is presented. In the method, the domain to be analyzed is divided into several subdomains. Analytical solutions are used for subdomains which have regular shapes but the FEM is used for irregularly shaped subdomains. The analytical solutions are transformed into relations between generalized forces and generalized displacements at nodal points located on the boundaries of the regular subdomains. This transformation is based on a type of energy method and concentrating stresses or flux. The resulting relations have the same forms as those of the FEM. Therefore, the solutions for the regular subdomains can be joined directly to the FEM solutions for the irregular subdomains. As simple examples, some two-dimensional acoustic problems are analyzed by this method. It is confirmed that the method brings about more accurate results and shorter computational time in comparison with the FEM only.

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In order to minimize the height of a wire-winding-type growing apparatus for silicon single crystals, a wire-rope winding method or a ball-chain winding method is used instead of a stiff shaft pulling a single crystal. When the wire-rope or the ball-chain rotates, amplitudes of the whirling vibration increase gradually with time, and a self-excited vibration occurs. In this paper, the cause of this self-excited vibration is studied experimentally using a model of the wire-winding-type growing equipment for silicon single crystals. The self-excited vibration of a wire-rope occurs when the rotation is above a resonant speed of the wore-rope system, and then only the forward whirling of a wire-rope becomes unstable, independent of the direction of an initially added whirling. On the basis of the experimental results, it is clarified that self-excited vibrations of silicon single crystal growing apparatus are due to an internal friction among element wires of the rope.

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This paper presents an application of a self-tuning regulator to the control of a known amount of granules from a hopper. Generally, there are many kinds of stochastic disturbances in processes handling granules. For such processes, it is difficult to obtain a good performance by using conventional control methods. Therefore, we attempted to apply the self-tuning regulator to the process. In order to do this, it was necessary to have models of the process dynamics and of the disturbances. First, modeling of the disturbances is discussed, and the self-tuning algorithm is applied to our process. As for the results, it is shown that the self-tuning regulator is more robust and is very useful for processes handling granules.

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For a better understanding of hunting, it is desirable to obtain the amplitude and frequency of limit cycle analytically. In the author's last two reports, as a first step toward nonlinear approximate analysis, the effects of individual parameters of a closed-engine-governor system on the instability of the equilibrium state, especially on the frequency and increment of amplitude, were linearly estimated. In the present report, results show that the limit cycle disappears over the whole speed range if the moment of inertia of the crankshaft system exceeds 1.8 times that in the actual engine; this phenomenon resembles the disappearance due to minimized subventuri pressure lag. Results also show that the amplitude decreases, except at extremely low speeds, with decreasing mass of the governing system, although mass reduction is difficult in reality. Further, it is found that the limit cycle does not disappear no matter what value the damping of the governor may take.

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This paper deals with the nonstationary oscillations of a flexible rotating shaft with nonlinear spring characteristics. In particular, we investigate a phenomenon during constant acceleration and deceleration passing through a critical speed of a 1/2-order subharmonic oscillation of forward precession. In numerical simulations, we examined the influence of the angular acceleration λ and the initial angular position ψ₀ of a rotor unbalance on the maximum amplitude of the subharmonic oscillation. As a result, the following points are clarified: (1) the maximum amplitude depends markedly on λ and ψ₀; (2) in order to always pass through this critical speed with finite amplitude during acceleration, an angular acceleration greater than a certain value λ₀ is necessary; and (3) when the angular acceleration is less than this critical value λ₀ (0<λ<λ₀), the shaft's ability to pass through this critical speed depends on ψ₀. We ascertained the validity of these theoretical results by experiments.

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Vibration analysis of infinite thick rotating cylindrical shells is described on the basis of the two-dimensional elasticity theory. Starting from the state of plane strain, the basic equation in the steady rotating state, which is used to obtain the initial stresses, is derived from Hamilton's principle, and the frequency equation, including the effect of the initial stresses due to the rotation, is formulated by Ritz's method. The numerical results for the frequencies in the non-rotating stare are compared with those based on Timoshenko-type shell theory and the available range in the latter theory is examined in terms of the thickness and rotating speed of a shell.

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The resonant amplitudes of grouped turbine blades were experimentally measured and theoretically calculated to determine the difference between calculated and experimental values. The blades were excited by an electromagnet, and the calculated values of the resonant amplitude distribution at the natural frequency were found to agree with the measured values. At some measuring points, a difference occurred between the calculated values and the measured ones, and in the worst case, the measured values became about twice the calculated ones. The calculated values also agreed well with the measured ones with regard to the direction of vibration and resonant stress. Therefore, if the operational exciting force can be estimated when designing the blades, the vibration amplitudes and stresses of the grouped blades can be calculated with some certainty. This is very useful for producing well-designed grouped blades.

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Turbine rotors and compressor rotors are subject to centrifugal and thermal loads. These loads increase proportionally with tip speed and gas temperature. Additionally, rotor weight must be decreased to improve rotor dynamics and to restrict bearing load. Thus, an optimum design technique which offers the lightest possible wheel shape under the stress-limit restriction is required. This paper introduces an optimum design system developed for turbomachinery rotors, and discusses several applications. The sequential linear programming method is used in the optimizing process, and unsteady state thermal analyses of variable thickness wheels are performed using a numerical analysis of a multiring model. Centrifugal and thermal stress analyses of these wheels are performed using Donath's method with the same multiring model. This optimum design program is applied to the design of axial flow compressor wheels. Finally, the validity of these applied results are confirmed by transient thermal and stress analyses using the finite element method.

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For units of rolling stock, which produce a tractive effort utilizing adhesion between their wheels and the rail, adhesion performance is very important. To improve this, the development of driving force control systems which attain optimal use of adhesion is necessary. So, a__-daptive c__-reep c__-ontrol (ACC), which controls driving force at the maximum point of friction force using creep speed and its differential value, has been developed. For the application of ACC to chopper electric railcars, two systems were developed. In one, all driving axles (ACC-V) were equipped with speed sensors, and in the other, motor voltages were used (ACC-E). Both were tested using a test car. The test results showed that ACC-V and ACC-E could control the driving force near the maximum point of the friction force, and attained about a 25% larger mean vehicle acceleration under wet rail conditions, compared with a conventional system.

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The step response in the axial direction of a rotor suspended by five axis-controlled active magnetic bearings was measured and compared with two kinds of numerical simulations: the Simple model, and the FEM model. Tests were performed on a large rotor displacement which exceeded the linear range of the design condition. The agreement of the simulated results of the FEM model with those of the experiment was better than with those of the Simple mode. Factors considered only by the FEM model were two-dimensionality of the magnetic field including leakage flux, voltage-current characteristics of the control coil, nonlinear magnetic characteristics of the pole pieces (B-H curve), and eddy currents. The most influential factor was the magnetic leakage flux which increased the induced voltage and the time constant of the control coil.

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The bearing characteristics, such as bearing stiffness and damping coefficient, of an externally pressurized gas-lubricated thrust collar bearing with multiple supply holes are analyzed theoretically. A point-source solution is applied to strictly evaluate the bearing characteristics. The dispersion effects due to the discrete location of the supply holes are discussed by comparing the point-source solutions with the solutions obtained under the line-source assumption. The effects of the deviation of bearing forms, such as the perpendicularity of the rotor end surface, size deviation of the supply holes and flatness of the bearing plate, on the bearing characteristics are also discussed.

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In this paper, a type synthesis system for production of prototype spatial multilink mechanisms constructed with multiple closed loops is investigated. This study was carried out to obtain optimum arrangements of links in the mechanisms. Consideration was given to the restrictive conditions of the mechanisms to be produced; i.e., closed loops in the mechanisms were constructed with some open chains, which are called open-chain elements in the present paper. Moreover, optimum conditions to satisfy the types of spatial mechanisms required were formulated using characteristics of the above-mentioned open chains, and a type synthesis system which determines the types of spatial multilink mechanisms was obtained. Applying the system, we synthesized a type of spatial six-link mechanism as a practical example.

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A new method of obtaining shrink fir between a ceramic shaft and an outer metal ring by means of a shrink fitter is reported in this paper. This shrink fitter, which is ring-shaped and has a higher coefficient of thermal expansion than the outer ring does, was inserted between the ceramic shaft and the outer ring. The shrink fitter was cut in the radial direction into several pieces. The fitting strengths of these shrink-fitted assemblies were measured from room temperature up to 600°C°C. The effect of the number of cuttings in the shrink fitter on the fitting strength at elevated temperatures was researched. It was revealed that the cutting of the shrink fitter into three pieces or more was requisite to ensure the fitting strength at elevated temperatures. It was possible to design the fitting strength-temperature relationships by changing the thickness of the shrink fitter in the radial direction. For example, the fitting strength would increase with temperature when the shrink fitter was sufficiently thick, and the fitting strength would decrease with temperature when the shrink fitter was sufficiently thin. Expressions which estimate the fitting strengths of the shrink-fitted assemblies are also developed in this paper.

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In order to obtain accurate steel gears by hobbing, not only are accurate hob and rigid hobbing machines necessary, but tooth surface smoothing is also required. Recent studies have shown that a very smooth tooth surface can be hobbed with cemented carbide or cermet-tipped hobs for hardened and tempered gears. In this report, the tooth profile errors of steel gears by finish hobbing are investigated and the possibility of obtaining highly accurate gears by hobbing is discussed. As a result, it is clarified that the tooth profile errors of steel gears are mainly caused by the geometrical errors of hobs and the setting eccentricities of the hobs tested. Therefore, if using accurate hobs and hobbing machines with sufficient stiffness and selecting suitable cutting conditions, steel gears can be accurately manufactured by hobbing.

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To elicit a fundamental tooth profile design policy for the scoring of spur gears, the effects of tooth profiles on scoring behavior were examined taking into account the two-cylinder test results. The tip interference on the approach side markedly affects the scoring phenomena. Both the reduction of the maximum specific sliding on the geometrical working flanks and the avoidance of tip interference on the approach side are essential conditions when attempting to obtain spur gears having superior scoring load capacity. In the mixed lubrication state, where the scoring occurrence has an intimate relation with the working flank bulk temperature, the scoring bulk temperature of a spur gear pair with no tip interference on the approach side can be estimated accurately by the bulk temperature on the outer surface of the cylinder immediately before seizure in two-cylinder tests.

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Estimation of the errors of a hob and a hobbing machine is necessary in order to improve the hobbing accuracy. This paper focuses on the configurations remaining on the tooth surfaces of hobbed gears, and illustrates analytically the tooth surface configurations caused by the errors of the hob and the hobbing machine. The errors of hobs concerned are the lead variation and the eccentricity, while the errors of the hobbing machine include the variation of the rotational center and the rotational irregularity of the table. The above-mentioned hobbing errors are closely related to the tooth surface configurations, and particularly, the feed marks express the characteristics of the tooth surfaces very well. As a result of the investigation on the tooth surface configurations and the formation mechanism of the feed marks, it is possible to estimate the hobbing errors by the calculated tooth surface configurations of hobbed gears.

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A crosshead-pin bearing equipped with axial oil grooves in a two-stroke cycle diesel engine cannot form an oil film adequate to keep the bearing trouble free at all times, because the bearing is subjected to high load in a single direction besides a low oscillating speed. This paper refers to a theoretical analysis of the lubrication of a crosshead-pin bearing system with a circular journal and an elliptical bearing. The bearing with a proper bearing ellipticity produces a considerably thick oil film and is superior in load-carrying capacity and oil-film exchanging ability to the conventional bearing, since the wedge film action greatly increases due to the presence of two converging-diverging clearance shapes in the load-carrying film.

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In our previous paper, it was shown that the ring-shaped spur gear can be formed by successive indentation of a rack-shaped punch. A ring-shaped specimen is deformed by the flow of the indented material in the circumferential direction during working in this method, causing changes in the pitches of the formed grooves. The specimen is observed experimentally to be deformed with a similar pattern throughout working. A deformation model of the specimens is proposed using an elastic-plastic finite element method to simulate the actual deformation behavior. Spur gears with a maximum accumulated pitch error of 0.3 mm are produced by indentation of a rack-shaped punch with pitches determined theoretically based on this deformation model.

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A temperature sensor for detecting temperature and heat flux on the roll surface in rolling has been developed. Installed in a roll surface, this sensor detects two temperatures at different depths from the roll surface by thermocouples. Surface temperature and heat flux are calculated from the two measured temperatures using the reverse calculation method for one-dimensional unsteady thermal conduction. Temperature distribution and heat flux distribution on the roll surface are measured in the cold rolling of aluminum sheets and billets. The availability of this sensing method for the investigation of thermal phenomena in rolling is discussed.

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A spinning axis, when secured to the wheel of a gyroscope, exerts a force on the workpiece and tracks the contour of the workpiece due to the gyroscopic effect. If a workpiece is used as a template, the force will provide the necessary cutting force for the grinding operation. The grinding condition is influenced by many factors including the template geometry and the normal and tangential reactions at the point of contact. This report examines the mathematical model governing the mechanism of gyrogrinding and determines optimal conditions for continuous grinding with no dynamic shattering of the template.

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In this investigation, a computer-aided-design method for a six-section elliptic tire-building drum is presented instead of the traditional geometric construction. The mathematical formulation of the proposed CAD technique is discussed in some detail. The efficient recursive equality-constrained quadratic programming method for solving constrained optimization problems is introduced to synthesize the mechanism of the drum. One practical problem is solved to illustrate the method.

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