When pipe wall vibrations are coupled with its internal acoustic waves in the cricumferential and axial mode, the pipe wall vibrations are presumed to add to the coupling frequencies. The coupling frequency is dependent on acoustic wave speed, pipe wall diameter and thickness. In this study, it is experimentally examined how flow turbulence caused by valve choking excites the coupling vibration. In this experiment, the fluid is air, and the pipe diameter is about 100 mm. The predicted coupling frequencies are about 2 kHz and 3. 5 kHz. Valve choking, the pressure condition for which is near or above the critical pressure ratio, causes flow turbulence with broadband frequencies. Referring to the experimental results, the relationship between the coupling vibration and the pressure ratio at the choking valve is discussed. It is confirmed that valve choking can induce large pipe wall coupling vibrations and noise.

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This paper describes a convenient method of identification of a nonlinear vibration system by a neural network using time series data. A neural network using a suitable system of inputs and outputs is applicable for system identification of nonlinear vibration by learning periodic response. By learning only time serie data of periodic response in coexisting regions of chaos and periodic response, it is possible to predict both forced vibration chaos response and periodic response on predicting conditions near learning data by the neural network. The effectiveness of the method presented is demonstrated by numerical simulations for the Duffing system.

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This paper deals with optimum design of a damper using electro-rheological (ER) fluid having apparent viscosity that can be modified by an electric field. The authors propose new characteristics of damping force that are expressed as a function of road profile and horizontal position of the damper on the road in piecewise linear form, using the fact that the damping force of the ER damper and piston speed of the damper are almost independent each other. The maximum acceleration of a vibration system with the optimum ER damper which passes over a versine protuberance is less than that with the optimum existing damper for which the damping force is expressed as a function of piston speed of the damper.

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In this study, we applied an impact mass damper to a scale model of C-frame turret punch presses and investigated the effect of reduction of vibration and noise. The influence of the contacting conditions between the damper and the frame on the damping characteristics is basically analyzed by the finite-element method. From the simulation, it is found that the apparent spring constants can be changed by adjusting the contacting force of the impact mass damper with the main frame. Moreover, the experiments were conducted in order to reduce the vibration and noise by using the impact mass damper. As a result, the amplitude of the tuning vibration mode, that is the first resonant vibration mode of C-shape structures can be reduced to up to 10% of the original model without any damper, and the noise level can be also reduced by over 6 dB.

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Phenomena such as singing flame or Rijke tube are types of heat-induced vibrations of an air column in a tube and are also classified as vibrations coupled with fluid motion. In a previous paper the growth process of air column vibration was successfully simulated by solving the equations for the thermoacoustic fields, and the fundamental mechanism of air column vibration in the range of small amplitude was discussed. In this paper the computation is extended to the stage when nonlinear vibrations occur. From the results, it appears that the change of amplitude growth rate of pressure variation is influenced by both the reversed flow pattern around the heater and the energy dissipated by viscosity. The time variations of the energy for excitation and dissipation are evaluated by computation. Calculated results of amplitude growth rate are compared with experimental ones for a vertical tube.

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Noise of panel-composed structures is mainly caused by panel vibration with atmosphere-pressure fluctuation. In order to reduce noise, a large quantity of damping material has been pasted on panels. In vibration intensity (VI) analysis, the flow of vibration energy (power) is expressed by vectors, showing the energy propagation routes on panels at a certain mode of vibration during forced vibration. This paper shows the calculation of dissipated vibration energy from VI values and clarifies the relationship between damping material and vibration reduction. First, this paper shows that results of the measurement by the cross spectrum technique correspond with results of calcula-tion using the finite-element method (FEM), and that quantitative analysis of dissipated energy is possible using VI on a two-dimensional structure composed of a panel and frames. Second, VI is analyzed on a three-dimensional structure composed of panels and frames, using FEM in consideration of internal forces for applicaion to real structures. The distribution of dissipated energy is calculated from the results of VI analysis of panels, and the effect of damping material pasted on panels is clarified. The effect on vibration reduction is verified for damping material pasted on the area where much energy is dissipated on panels.

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The engine mount plays a vital role in the improvement of riding comfort, driving quality and noise level. Its characteristics are specified through spring constant and damping ratio. It alone does not have sufficient characteristics in the required frequency range. In this paper, the desired spring constant and damping ratio are realized by using a discrete-time controlled actuator. We formulate this problem as a model matching problem, and control the plant to follow the reference model which has the desired spring constant and damping ratio. The plant is controlled by a discrete-time actuator, whereas the reference model is of continuous time. Therefore we minimize the error between reference model and plant by using an optimal regulator, taking into account the behavior between sampling times. We confirm the efficacy of this method by computer simulation.

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A chopping system moves a secondary mirror rapidly and precisely to enhance the weak source signal-to-noise ratio of an infrared telescope. Furthermore, a chopping system of a large telescope must enable non-excitation of telescope mechanical resonance and reduction of mass of a chopping mechanism, In this study, a unique chopping mechanism and a new control system are proposed. The mechanism has a light active damper driven by the same linear motor which drives a secondary mirror. The control system is a 2-degree-of-freedom control system with a unique command signal that enables rapid and precise motion of the chopping mechanism. Effectiveness of this chopping system is proven by application to a 500mm-diameter-secondary mirror.

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The basic equation of motion for the full system of a hydraulic pump with a swash plate has been formulated using the model of 20 D. O. F. and 4-mass system. In order to evaluate the applicability of this model, numerical analysis of the dynamic response of this system due to the pressure pulsation has been carried out and compared with the experimental data. Satisfactory agreement between both calculated and experimental results is obtained. A series of response analysis has been carried out by varying main parameters, and influences on response for each component were clarified.

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This paper describes the dynamic test results of a peripheral restraining-type rubber bearing which has adjustable damping ability. The rubber bearing is composed of a core block made of superhigh-damping synthetic rubber and a restraining ring made of high-damping rubber surrounding the core block. The rubber bearings used for the fundamental tests are 0. 3-scale models of actual bearings. The test results are compared with the test results of actual bearings. The fundamental tests reveal the various properties of the horizontal stiffness and damping ratio obtained from the hysteretic restoring force loops. The horizontal stiffness and damping ratio are not affected by amplitude and frequency over ±0. 5 shear strain amplitude. Moreover, the rubber bearing can retain its horizontal stiffness and damping ratio after the 1 000-cycle repetition test under unit shear strain amplitude. The results of the 0. 3-scale model nearly conform to the results of the actual bearing. The experimental results show that the ability of the actual bearing can be estimated by testing the 0. 3-scale model.

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This paper deals with the damping properties of a viscoelastic three-layered cantilever with partial delamination in the damping material. In the analysis, first, the flexural rigidity of a three-layered cantilever without delamination is calculated by means of the neutral plane method in the previous paper. Next, the flexural rigidity of the three-layered cantilever with delamination corresponding to the fundamental mode of vibration is determined by measuring the static deflections. Finally, these values are used to evaluate the complex flexural rigidity corresponding to arbitrary normal mode, and the loss factor for each normal mode is obtained. As a result, it is clarified that delamination makes the magnitude of the loss factor considerably larger than in the case of no delamination. Comparison of the theoretical results of loss factors with the experimental values shows that this analytical method has higher accuracy than the previous method.

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Parameters such as the principal moment of inertia, principal axis of inertia, and location of center of gravity are necessary for simulation of the dynamic properties for the design of a mechanical system. Usually some of these rigid body properties are identified by the pendulum method, which is an experimental procedure to obtain these from the period of the suspended specimen using the principle of a pendulum. However, as the specimen becomes more complex in shape or heavier, the resulting parameters are identified with poorer accuracy, because the accuracy of location of the center of gravity decreases. Therefore, the authors examine an approach for experimental identification of the characteristic matrices, i. e., the mass, the damping and the stiffness matrices, using the modal parameters obtained by modal testing applied to obtain the automotive subsystem's rigid body properties. From these results, it is shown that this approach can be used for obtaining the rigid body properties of mechanical systems.

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Reduction of the noise emitted from the automobile alternator has recently become a serious issue, especially in relation to the improvement of the amenity of driving. We intend to analyze electromagnetic noise of the alternator and to clarify some sources and causes of the noise. The study consists of the following three steps : ( 1 ) measurement of noise from the rotating alternator, ( 2 ) experimental modal analysis through the measurement of natural frequencies of the components, ( 3 ) comparison of the approximate value calculated theoretically with the data from vibration tests. The theoretical and experimental analyses revealed the relationship between the noise and vibration of the alternator. The results obtained are applicable to alternator design for the reduction of noise.

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The noise of an automotive brake system is known to be self-excited vibration caused by friction and various improvements have been incorporated. These improvements were made by many methods such as change of resonance frequency by changing the stiffness of the brake structure and change of the damping and friction characteristics of lining material. However, at present there is no definitive correction method. The purpose of this paper is to clarify the prevention method of self-excited vibration by fixing a carbon graphite lining with improved friction characteristics to one part of the original lining area. A heavy-duty truck with L-T type drum brake was tested and theoretical calculation was conducted using complex eigenvalue analysis by a multi-degree-of-freedom spring mass coupled vibration model.

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Orthodontic treatment utilizes the biomechanical adaptive deformation of alveolar bone in response to external forces. The alveolar bone resorption rate is one of the fundamental factors for describing a remodeling process of the hard tissue. This paper describes a new estimation technique for the resorption rate during orthodontic treatment. We estimated the amount of alveolar bone resorption from clinical measurements of 3-D tooth movement during the treatment. We also calculated the stress around the tooth root with 3-D finite-element analysis. These values were obtained under the various conditions of clinical treatments. The rate to a unit stress obtained from the maxillary canine of patients was found to be 0. 6 ± 0. 2 μm/ (kPa. day) .

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The singularities of the output signals from a physical system depend upon both the singularities of input signals and the regularizing property of the physical system. Wavelet analysis is adequate for analysis of these singularities. In this paper, wavelet analysis, using Daubechies' compactly supported orthonormal wavelet basis, is applied to signals having impulse singularities in certain derivatives. To analyze singularities of this kind, the wavelet function must have regularity and vanishing moments. Daubechies' wavelet functions are parameterized by N, which is related to the regularities of wavelets and to their vanishing moments. For several signals having an impulse singularity in certain derivatives, the minimum integer N for analysis of singularities of this kind is determined by numerical calculations, and for several output signals passing once or twice through, a transmitting system expressed by a second-order differential equation, the minimum integer N for analysis of singularities of this kind is also determined by numerical calculations. From these examples, we conclude that choosing appropriate N, the parameter of Daubechies' wavelet function, her compactly supported orthonormal wavelet basis, is applicable for detection of impulse singularities in certain derivatives of input signals if both the regularizing property of the physical system and impulse singularities in certain derivatives of their output signals are known.

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Robust control of a closed-loop pressure control system is investigated in this paper. Dynamics of a pipeline which connects a control valve and an actuator may affect the closed loop system stability. A simple reduced-order model of pipeline dynamics is preferable for control system design. Evaluating uncertainty of the reduced-order model based on a finite-element model, an H_∞ controller is designed. An experiment on closed-loop pressure control has been carried out to demonstrate performance of the H_∞ controller and to illustrate the importance of modeling pipeline dynamics.

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An integrated structure/control system design method is applied for the control system of the D-3 VTR tape path system. For the purpose of obtaining an integrated structure/control anlytical model with high accuracy, an analytical model of the VTR tape path mechanism is constructed first so as to represent the dynamic characteristics of a mechanism well. The integrated structure/control model is made by combining the VTR mechanism model with a control system model. This integrated model enables us not only to obtain sensitivity information for design improvement but to optimize mechanical and control system simultaneously. Control system design optimization is performed using this integrated analytical model to reduce tape tension fluctuation under high acceleration and deceleration operation. The advantage of this integrated analytical model and new control system is shown by the test using the prototype system.

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For intersatellite communication, precise antenna-pointing control with wide range and high scanning rate is required. For this purpose, the antenna-pointing mechanism with two degrees of freedom driven by step motors is used. Because structural vibration modes in the controller bandwidth degrade the performance of antenna-pointing control and spacecraft-attitude control, we require antenna-pointing control without excitation of the vibration modes. In this paper, we propose a new antenna control scheme having the function of active vibration control. Its robustness against modelling errors is examined by the normalized coprime factorization approach. Numerical simulations and hardware experiments have been carried out in order to verify not only the controlscheme but also the modelling technology. It is concluded that the proposed control scheme is more effective in suppressing the vibration modes as compared with a conventional control scheme.

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A new adaptive control algorithm in frequency domain was proposed. This frequency domain approach corresponds to the ordinary filtered-x least mean square (LMS) algorithm in discrete time domain. In this approach, the fast Fourier transform (FFT) was used for converting signals between frequency domain and discrete time domain. Since the computaion processes in these two domains are almost independent with each other, this algorithm can be realized effectively by using two processors. Computer simulations were carried out for investigating convergence characteristics of this approach. As the result of these simulations, it was shown that this algorithm has faster convergence with less computation comparing to the ordinary filtered-x LMS algorithm.

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Repulsive magnetic levitation systems with magnets driven by actuators were studied in this paper. In one system, a levitation magnet was driven in the direction of repulsive force to control the position and vibration of the levitated object. In another, a levitation magnet was moved in the lateral directions to stabilize the system in the manner of an inverted pendulum. The first type was studied experimentally with an experimental setup using a magnetostrictive actuator. The damping characteristic was modified well by driving the actuator in proportion to the velocity of the levitated object. The I-PD control was adopted for obtaining desired characteristics of floating position control and active damping of vibration.

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Constant feedback coefficients of nearly optimal PID control of the magnetic suspension system for the linear driving mechanism were derived, and its robust stability against the scanning movement of the driven part was verified. The root loci have shown that the stability region of the system is narrowed by only 15% by neglecting the crossterms of the feedback coefficients. The stability analysis using the root locus method showed that the time delay inherent to the magnetic actuators, which was neglected when the optimal control rule was derived, has a substantial effect on the system stability. However, an allowable time delay in the control loop can be estimated to guarantee the system stability, even with scanning motion of rather long stroke.

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One of the inherent limitations of active controlled suspension is the existence of an invariant point related to unsprung natural frequency. Aiming at the improvement of the ride quality at the invariant point, we focussed on a seat control equipped with an actuator between seat and body. From a functional point of view, the seat deflection must be small. Frequency-shaped functions are applied so that the seat control is effective at the frequency range, with small seat deflections at low frequency. As a result of dynamic simulations, it was clarified that the seat control is useful for vibration reduction at the desired frequency range and that integrated control of the suspension and the seat effectively improve ride quality.

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This paper deals with an identification of contact points between finger links and a grasped object in an enveloping grasp. The grasp has the following merits. One merit is that the grasp is firmer than a fingertip grasp and a distal link grasp. Another merit is that error of contact points is recognized because the object is grasped by inner links. However, it is difficult to identify contact points and contact forces. These parameters are necessary to control the object, not to destroy it, and to shift to an optimum grasp. We propose an analytical method for an identification of unknown parameters, such as contact points and forces, by active sensing in the enveloping grasp. A necessary and sufficient condition for the identification is provided.

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This paper reports the dynamic characteristics of human stair walking, particularly the transient during starting and stopping phases. The transient characteristics in human walking, especially in stair walking, has rarely been studied because of the difficulty of experimental measurement. Large force plates, on which two staircase models having 5 stairs are set, were used for measuring both three orthogonal components of the reaction force and its point of application in four different walking modes. In this paper, experimental results in stair walking are compared with those in level walking to make the distinct characteristics of stair walking clear. The velocity and the displacement of the mass center of the entire human body are obtained by numerical integration of the reaction force components, once or twice, respectively. The following results are obtained : the behaviors of the reaction force and the motion of its point of application in stair walking are more complicated than those in level walking ; this finding suggests that the stress appearing at joints is bigger in stair walking.

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This paper proposes an inclination control algorithm of the Omnidirectional Walking Mechanism, which consists of a parallel link mechanism connecting two frames with three linear actuators and six elastic legs. The relative position and angle of the frames are selected arbitrarily by three actuators. Walking motion is produced by combining them with extendable legs. The ground is not always flat, and many different levels and obstacles exist, so posture control is essential for robot-labor. Posture of the robot can be controlled by changing the lengths of the legs referring data from inclination sensors. We constructed an experimental prototype model, and used the above method to control the inclination of the upper surface of the prototype model. The performance was investigated in terms of motion in every direction and over steps, and as a result of the experiments, it is confirmed that this robot can walk in all directions and can walk on a gentle slope by controlling the inclination of the upper surface.

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This paper deals with the quasi-dynamic walk of a quadruped locomotion robot using a frequency-shaped optimal tracking control method. In the case of control for a locomotion robot, high feedback (FB) gain should be used in order to compensate the force and the moment from the body and the reaction force from the ground. But if high FB gain is used, high-frequency vibration occurs because of the backlash of the gear. Frequency-shaped optimal control is a control method to improve the robustness against disturbances of this kind. Frequency-shaped optimal tracking control is used to extend frequency-shaped optimal control to a servo system like the trajectory control of the robot. First, we show the design method of frequency-shaped optimal tracking control. Next, decentralized control is realized to apply frequency-shape optimal tracking control. Finally, frequency-shaped optimal tracking control is compared with optimal tracking control from the point of view of simulations and experiments.

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In this research, we address the organization of group behavior on decentralized autonomous robotic systems. Collective group behavior is exhibied in the natural world, such as by ants and fish, in teamwork in sports and by the human society. Therefore, research on group behavior of decentralized autonomous robotic systems can be regarded as one of the research fields of Artificial Life. Decentralized autonomous robotic systems refer to multiple robotic systems including many autonomous robots, such as the Cellular Robotic System (CEBOT). The CEBOT, which has been studied by the authors, consists of a number of robotic units called "cells". In the research on the CEBOT, it is necessary to evolve a cooperative group behavior effectively in the system, since a well-organized group behavior is required to carry out given tasks efficiently and influences its perfor-mance ability. In order to organize the behavior in a dynamic environment, we proposed a concept of "self-recognition" for decision making of the behavior in a robotic group. In this paper, in addition to the proposed concept, we will show the organization and adaptation of group behavior with the coordination of intention, and represent some simulation results with the coordination of intention.

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Manipulating an object is one of the most important tasks of robots. Many studies have been carried out on object control algorithms and optimizing control force. Most of those studies, however, deal with objects whose properties are previously known. In this paper, a control method for unknown objects is proposed using a fuzzy neural network. The controller consists of a main controller for trajectory control, and subcontrollers for manipulator force control, of an unknown object. Since manipulators have to apply specified force to an unknown object, the environment estimator is set in the subcontroller in order to avoid large overshooting which might damage the object. Computer simulation was performed to evaluate proposed controller.

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This research is concerned with a new technology for image recognition of objects using neural networks. Although human beings have an excellent faculty of pattern recognition, the process of pattern recognition has not yet been clarified. Numerous studies have been developed to realize computer vision similar to the human faculty through image processing technology. However, if objects essentially have fuzziness among categories, recognition is difficult. In this study, pattern recognition including such fuzziness is investigated, and a new image recognition system is proposed with application of neural networks able to extract features by direct scanning of the pattern. First, the traffic speed mark is detected by dividing the image in terms of brightness and hue. Second, speed mark figures are extracted by processing the area of the speed mark. Third, since speed mark figures include patterns with noise and loss, new patterns are produced by changing a lower pattern to a higher pattern. Finally, some recognition experiments are performed for four categories of speed mark figures using neural networks. From these experimental results, it is shown that the new technology proposed here is sufficiently valid for recognition of objects of a natural image.

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The traction characteristics for a point contact are evaluated with the model of the limiting shear stress of lubricants. The influences of spin and skew on the initial slope of the traction curves are also investigated. The traction coefficient will drop severely for a very small skew angle, but it not so sensitive to the spin rate. With the skew angle or spin rate, the initial slope of the traction curves decreases at the heavy loads. The approximate formulas for the with-spin traction coefficient and for the with-skew traction coefficient are proposed based on the examination of the calculated shear stress.

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The frictional behavior of candidate materials for artificial cartilage lubricated with constituents of synovia was examined in the one-directional sliding test and the knee joint simulator test. Artificial cartilage materials were used to preserve the fluid film between articulating surfaces by soft elastohydrodynamic lubrication (EHL), and to overcome tribological problems, such as loosening and wear, in total knee prostheses. However, some of them exhibited unacceptable high friction in the mixed lubrication region. In this study, we tested polyvinylalcohol (PVA) hydrogels and polyurethanes (PU) as artificial cartilage, and compared their frictional behavior with an ultrahigh molecular weight polyethylene (UHMWPE). Solutions of the sodium hyaluronate (HA) were used as lubricants, and serum proteins were added to examine their effects on the frictional behavior. As a result, the PVA hydrogel, which has high water content, showed favorable frictional behavior under the thin film condition, and serum proteins functioned as boundary lubricants. The artificial knee joint model with a PVA hydrogel (high water content) as arificial cartilage exhibited excellent frictional behavior during walking when it was lubricated by the HA solution with serum proteins.

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The occurrence of numerous shallow radial cracks observed on the rubbing surface of cemented carbide rings composing mechanical seals is influenced by various factors. The role of these factors is discussed based on experimental results. The experiments were conducted by pairing cemented carbide rings with an alumina ceramic ring or a silicon carbide ring fabricated by reaction bonding under conditions with and without distilled water being sealed. It has been pointed out that surface cracking is caused by dynamical action due to high contact stress and high friction force rather than thermal stresses produced as a result of frictional heating.

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A possible mechanism of the occurrence of numerous shallow radial cracks observed on the rubbing surface of a cemented carbide ring composing mechanical seals has been proposed on the basis of experimental results reported in a previous paper. The cracks appear to be caused by high contact and tangential stresses resulting from the concentrated contact patches that move around the seal face. To elucidate the proposed mechanism, elastic-plastic analyses of the subsurface layer of the seal ring have been conducted using the finite-element technique. The numerical results obtained have shown that the proposed mechanism can explain the experimental results well and is reliable.

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Frictional characteristics of a band brake which is often used as a braking device in automatic transmission were investigated experimentally and theoretically. The oil film thickness between the band and the drum was visualized at the onset of band brake engagement. Calculations were made on the relationship between the oil film distribution and the oil temperature, oil flow rate, load pressure of the brake lining and other parameters. It was found that the initial coefficient of friction of the band brake depended on the mean oil film thickness.

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This paper presents a new theory on frictional vibration observed in wet clutches or wet brakes, considering poroelastic characteristics of paper-based friction material. A stability criterion is derived on the assumption that vibrations in two directions, tangential and normal, are coupled. In comparison with experimental results, it is confirmed that the criterion can predict the stability limit more accurately than the conventional one, which does not consider deformation of friction material and depends only on the gradient of friction coefficient to sliding velocity. Based on the criterion, influences of material properties on stability to frictional vibration are discussed.

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In this report, the friction and wear of austenitic stainless steel spur gears of which the surface layer was thermally diffused after being Sn-plated were exammined in high vacuum. Gear tests were carried out under grease lubrication and dry friction in vacuum of about 2 x 10^-3 Pa using a power-circulating gear test rig. From the tests, the following results were obtained. ( 1 ) In the case of grease lubrication, the ratio of the gear frictional loss torque to the transmitted torque was in the range of 0. 01 to 0. 05. ( 2 ) The time to reach destructive surface failure of the gears due to thermally diffused treatment was significantly long. This long time was observed in both dry friction test and grease lubrication one. The optimum diffused layer thickness was about 4 μm in the case of grease lubrication. ( 3 ) The acceleration of the gear box when the gear tests could not proceed due to destructive surface failure was significantly increased, and then the destructive surface failure could be detected by means of the measurement of acceleration due to vibration of the tested gear box.

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In this study, an ordinary complementary crown gear generates both an actual spiral bevel gear and an imaginary spiral bevel gear whose pitch cone angle is 80^o∼87^o. The tooth surface of the imaginary bevel gear is replaced by a simple conical surface. The imaginary gear with the conical tooth surface is designated as a quasi-complementary crown gear and is used as a tool gear to generate the pinion. The quasi-complementary crown gear produces a tooth surface modification. As a result, the engagement of the gears is a point contact with a negligibly small non-conjugate. The complementary crown gear and the quasi-complementary crown gear each generate both sides of a tooth space of the work gear simultaneously because the cutter blades forming a tooth of each crown gear are widely spread by an adequate amount. The conditions which satisfy this duplex spread-blade method relating to both the complementary and quasi-complementary crown gears are shown in this PaPer.

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Shaping of an inner spline and an internal gear by extrusion was studied. Namely, the outer diameter of a hollow cylindrical workpiece was reduced by extrusion through a die. Then, an internal gear or an inner spline can be shaped by using a mandrel having corresponding teeth. The specifications of the splines and gears examined were as follows : splines-module m= 1. 0-2. 0, number of teeth Z = 8-16, tooth depth h = 1. 25 - 2. 5 mm : gears-m = 1. 0-1. 5, Z = 12-18, h = 2. 0-3. 375mm. The material used was S 15 C steel. The criterion for shaping complete teeth is discussed in terms of a reduction in area and a compressive stress on a punch. It is shown that these limiting values are about 40 % and 700 MPa, respectively.

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Precise slot grinding experiments were conducted on two kinds of polycrystalline Mu-Zn ferrites, which showed intergranular and transgranular fracture, respectively, to investigate the influences on fracture mode of changes in size and shape of the edge-chipping. In the case of using fine grain, maximum chipping size of transgranular-fracture-type ferrite was smaller than that of the inter-granular fracture type ; however, in the case of using coarse grain, maximum chipping size was reversely to the case of using fine grain. This reversed phenomenon was explained based on the differences in fracture mode of the materials. The percentages of intergranular fracture of these materials were examined in detail by SEM observation. The transgranular fracture type was suitable for precise slot grinding using fine grain. On the other hand, the intergranular fracture type was suitable for normal slot grinding using coarse grain. As a result, new technology for reducing the edge chipping which controls the grain boundary strength using an additive was developed.

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A coupled method for simulating non-steady-state metal flow and temperature distribution in twin roll strip casting is presented. The viscoplastic and the heat conduction finite element methods are used to calculate the metal flow and the temperature distribution, respectively, and the interaction between the metal flow and the temperature distribution is taken into consideration. In the viscoplastic finite element simulation, a spatially fixed element mesh is employed to avoid severe distortion of elements. For the temperature analysis, the effect of latent heat due to solidification of molten metal is dealt with. The calculated profiles of the boundary between the solid and liquid regions in plane-strain twin roll strip casting agree well with those obtained from a model experiment using paraffin wax. In simulation of strip casting of stainless steel, the metal flow and temperature distribution become unstable when the solidified shell between the rotating rolls begins to flow reversely to the molten Pool.

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This study deals with the development of a new process for tube ironing. Tube ironing is performed in the absence of sliding friction which is the main cause for galling and breakage in conventional ironing. In this process, a number of rollers rotate around the cone while revolving around their respective axes. The "planetary conical rolling" process is termed PCR, and has the following advantages : ( 1 ) rollers are supported by a shaft free of lateral force, ( 2 ) the diameter of the shaft is almost the same as the inner diameter of the product, ( 3 ) high rigidity of the shaft results in high accuracy of products, and ( 4 ) rollers inclination prevents sliding between roller and material in the radial direction. Experiments are conducted on two processes, i. e., forward and backward, and two aluminum materials, i. e., A1050 and A5052 with different rotations, and feed rates. The results show that this process can produce a thickness reduction greater than 0. 89 with a mirror-finished outer surface.

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Applications of glass and ceramic materials to micro-machine elements in biotechnology and space engineering have led to a great demand for special machine tools which enable fine micro-machining on hard and brittle materials. The first part of this article describes a PZT actuator installed in a vibrating machine tool whose performance is tested on different materials. In the second part, we investigate the applicability of giant magnetostriction materials to a vibratory device for fine-micro machining tools.

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The effect of an electric field applied between rubbing surfaces on friction and wear characteristics was examined using a ball-on-disc testing apparatus under mixed or boundary lubrication conditions. When the friction characteristics improved, the balls were abrasively worn by the mating discs on which oxide films were formed mainly by anode oxidation. On the other hand, in the cases where friction was not decreased, the main wear mechanism was adhesive, similar to the cases without an electric field. The lowest limits of the voltage and short-circuit current of the electric field were determined in order to improve the friction characteristics. In addition, high voltage and short-circuit current caused the friction characteristics to deteriorate due to breakdown of the oil film builtup. Therefore, application of electric field results in quick running-in, and it seems to be better to cease applying the electric field after the friction characteristics improve.

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In order to estimate the fatigue life of welded bellows, so far, the fatigue test has been carried out using actual welded bellows, so that it took much money and time to develop a new type of welded bellows. In the present investigation, the S-N curve of welded bellows plotted against the stress amplitude calculated by the finite-element method and the S-N curve of a thin plate for welded bellows have been compared. As a result, it was found that although the fatigue life varies depending on the speed in the fatigue test, the S-N curve of the welded bellows is in close agreement with the S-N curve of a thin plate of welded bellows at the same test speed. Therefore, it is possible to estimate the fatigue life of actual welded bellows accurately utilizing the S-N curve of the thin plate of welded bellows, which is modified by the test speed.

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In order to estimate the transient thermal response between a die and a workpiece in hot and warm forging, we proposed a new estimation model for finite-element analysis. A uniform air film was introduced into the model to evaluate the thermal contact resistance rc of the interface. We analyzed the wide range of contact conditions experienced in forging processes and proposed equations to quickly evaluate their γc for analyzing the temperature fields of the die and the workpiece in practical forging processes. ( 1 ) The γc was mainly influenced by the microstructure of the workpiece surface and the contact conditions which vary during the forging process. ( 2 ) The workpiece covered with an oxide film and the die coated with a hard metal film had varying γc depending on the heat conductivity of the films. ( 3 ) The relative movement of the workpiece on the die surface negligibly reduced γc, but if the frictional heat created by slipping is distributed on the workpiece surface, γc must be modified appropriately.

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A self-calibration system of a pair of position sensing detectors (PSDs) has been developed. Without using any special standard, the linearity errors of a pair of PSDs can be calibrated intrinsically within their performance limitations. The changes of linearity errors of the PSDs according to spot sizes have been clarified by using the developed experimental setup. The difference between the linearity errors for different spot sizes is larger than the positioning error given in specifications by manufacturers.

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This paper presents a new method for roundness measurement, which is named the orthogonal mixed method. This method was developed from the mixed method that uses two displacement probes and one angle probe for measurements. The mixed method can not only separate the profile from rotational errors completely but also can detect high-frequency components having wave-lengths shorter than its probe distance. In this paper, it is verified that the best characteristics of the mixed method can be obtained in the entire frequency range if the angular distance between the displacement probe and the angle probe is set to be 90^o. This orthogonal mixed method has also the simplest probe setup because it needs only one displacement probe and one angle probe to separate the profile from the rotational error. The effectiveness of the orthogonal mixed method is confirmed by comparing it with the general mixed method and the 3-point method. This paper also presents a fundamental design guide to realize the orthogonal mixed method of nanometer accuracy.

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In the mechanism design of in-parallel actuated manipulators, kinematic constants must be clarified so that the singular points and the neighborhoods of singular points are not included and high motion transmissibility can be obtained in the prescribed working space. This paper proposes a new method based on the Monte-Carlo method for extracting the set of kinematic constants which assures high motion transmissibility in the prescribed working space. The proposed method is applied to extraction of kinematic constants of a type of spatial in-parallel actuated manipulator with six degrees of freedom with high motion transmissibility, and the results are discussed for four different combinations of kinematic constants. An important kinematic constant for obtaining high motion transmissibility is clarified which has never been treated as a design parameter. The effectiveness of the proposed method is also investigated by comparing the results to those obtained by the conventional method.

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A methodology for generating optimum designs based on an analogy of design generation processes which imitates the evolutional processes of living creatures is proposed in order to obtain a more preferable design solution without any preconceptions concerning the design. Here, design optimization is conducted from an initial condition where there is nothing except for the indispensable constraints. Incidental evolution and optimization are conducted simultaneously for a multiple number of chosen candidate design solutions. Evolutional generation and selection of design solutions are repeated for a group of these candidate design solutions until a satisfactory design solution is obtained. The proposed method is exemplified on structural design models.

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