An elastic rotating shaft supported by ball bearings may have nonlinear spring characteristics due to clearance and internal daming due to friction between the shaft and the bearings. In such a system, self-excited oscillations appear in the postcritical region and nonlinear forced oscillations appear at various resonance points In this paper, a phenomenon in the neighborhood of the critical speed of the subharmonic oscillation of order 1/3 of the forward whirling mode is discussed. It is clarified that, similar to the case of the subharmonic oscillation of order 1/2 of the forward whirling mode, an entrainment phenomenon appears due to the interplay between self-excited oscillation and forced oscillation.

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Transient vibrations of elastically connected double-beam systems are analyzed taking into account the effects of shear deformation and rotary inertia in accordance with the Timoshenko beam theory. The Finite Integral Transform technique is successfully applied to the elastically coupled two Timoshenko beams having different cross sections and being made of different materials, which are intractable by most other analytical methods. The analytical solution by the present technique results in a series expansion form in terms of generalized orthogonal eigenfunctions defined by the boundary value problem associated with the equations of motion for the system. By solving the boundary value problem, it is shown that there exist four series of eigenvalues and eigenfunctions. Transient responses due to impulsive loading as well as step loading are analyzed and compared with the case of the Bernoulli-Euler double-beam system. It is found that the Timoshenko double-beam system behaves in a slightly different manner from that of the Bernoulli-Euler double-beam system.

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Because of its low stiffness compared with ball bearings, a magnetic bearing-rotor system is easily affected adversely by foundation movement such as seismic vibration. Although built-in touchdown bearings function in an emergency, it is necessary to restrain a foundation-excited response of a rotor within the designed gap. In this paper, an acceleration feedforward control method is presented to reduce the relative response of a rotor to stator magnets caused by foundation movement. While a high proportional gain in PID control intended to increase bearing stiffness may cause instability, this method can reduce the dynamic compliance of the magnetic bearing-rotor system without altering its stability. Applying this acceleration feedforward control to an experimental apparatus, the relative response of a rotor to stator magnets caused by foundation movement is restrained to about half of the response with ordinary PID control.

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This paper presents the vibration analysis of a cross-ply laminated rectangular plate simply supported at all edges by using the multilayer theory. In the multilayer theory, in-plane and out-of-plane displacements are independently expressed as polynomial forms of third and second order, respectively, for each layer of the plate. A set of governing equations for the laminated plate is derived from the equations of motion, the free surface conditions and the continuity of displacements and stresses along the interfaces between adjacent layers. In contrast, the lamination theory uses only a single displacement field for the whole laminated plate. In numerical examples, natural frequencies, steady-state responses (compliance) and stress distributions in the thickness direction are obtained from both theories for plates with various thickneses and stacking sequences. Further more, a comparison is made between the two sets of results obtained, and the range of applicability of the theories is discussed.

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Structural intensity of the 2-dimensional vibrational field is investigated theoretically. It is shown that the intensity has a mean component which is independent of the coordinate and a local component dependent on the coordinate. The measurement of 2-dimensional intensity is far more difficult than that of 1-dimensional intensity because many sensors are necessary. The relationship between the vibratory displacement and intensity is also discussed. The sensitivity of the structural intensity measurement is shown by the precision of vibratory displacement. Small error near the boundary may cause a big difference in intensity. The 5-point method is thought to be optimal for actual applications. A wave decomposition method in a 2-demensional vibrational field is newly introduced, which can separate the total displacement into flexural waves and evanescence waves.

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This paper describes an analysis of anisotropic torsional resonators with the Ritz method and its application to quartz crystal tuning fork-type resonators which are easily formed by a chemical etching process. In this paper, resonant frequency and frequency temperature behavior of the resonators are clarified using the frequency equation which is given as a function of torsional rigidity derived from the Ritz method, and miniaturized torsional resonators with a small series resistance R₁ and a high quality factor are obtained. A torsional rigidity is first derived theoretically; then, a series of analytical results are compared with the measured data, Both results show good agreement, and a miniaturized resonator is successfully obtained with a small series resistance R₁ and a high quality factor particularly in the vicinity of 500 kHz.

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A finite-element method for vibration analysis of cantilevered rectangular parallelepiped rubber carrying a rigid body at one face is presented. Herrmann's variational principle is employed to formulate the mixed finite-element model applied to the rubber, which is nearly incompressible. The rigid body is treated as an element possessing mass and moments of inertia. By using the present method, lateral vibration analysis of a cantilever dynamic absorber composed of a rigid body and solid rubber with hysteretic damping is carried out to clarify the influence of inertial properties of the rigid body on the vibration characteristics of the dynamic absorber, such as natural frequencies, rigid body vibration modes and frequency response of the rigid body to sinusoidally varying displacement of the base to which the dynamic absorber is attached. The vibration characteristics calculated by use of the method are in good agreement with experimental results obtained through excitation tests of the dynamic absorber.

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Nonplanar lateral oscillation of a wire electrode, called self-excited oscillation, occurs when high electric voltage is applied between the wire and infinite plate electrodes with corona discharge. The purpose of this paper is to suppress wire oscillation using the nonlinear coupling effect, for a single-degree-of-freedom damped spring-mass system attached to the end of the wire electrode in the axial direction. It is clarified from the theoretical analysis that nonplanar oscillation of the wire decays through the effect of damping force on the supplementary system in the state of internal resonance. Furthermore, an experiment is conducted to confirm the relaxation of the wire oscillation. The experimental result is in good qualitative agreement with the theoretical one.

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This paper presents the effectiveness of a sloshing suppression bulkhead which divides the cylindrical or co-axial cylindrical vessel vertically into several sectors. The sloshing mode is separated into two modes by the bulkhead; one is the sloshing mode of the water column in a U tube, and the other is the sloshing mode in the sector tank. The motion of equation for sloshing in the divided cylindrical vessel is derived from Lagrange's equation. Two sloshing mode are shown by the equations to be decoupled from each other. The vertical bulkheads have the effect of decreasing the participation factor of the U-tube-shaped sloshing mode. The calculated results yielded by the equation for a model vessel and an actual size vessel are compared with the numerical results obtained by the CFD code and model tank test. It is clarified that the vertical bulkheads are effective in suppressing sloshing.

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A storey-installation type damper, which arranges the energy absorption system in each storey and effectively reduces the structural vibration caused by an earthquake or a wind, has been energetically researched and developed. Moreover, some systems have already been applied in practice. Although this type of damper is generally installed equally in each storey, the uniform placement not only causes a quantitative difference in the energy absorption capacity of the damper between the higher and lower storeys, but also exerts an influence on the construction cost finally. In this study, we attempt to apply a genetic algorithm (GA) to determine the proper distribution for the storey-installation type damper rapidly and easily. We describe the arranged results and effects when GA is applied to 5 and 11-storey building models to determine the proper distribution of the damper.

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Component and piping systems in current nuclear power plants and chemical plants are designed to employ many supports to maintain safety and reliability against earthquakes. However, these supports are rigid and have a slight energy-dissipating effect. It is well known that applying high-damping supports to a piping system is very effective for reducing the seismic response. In this study, we investigated the design method of the elastoplastic damper [energy absorber (EAB)] and the seimic design method for a piping system supported by the EAB. Our final goal is to develop the technology to apply the EAB to the piping system of an actual plant. In this paper, the vibration test results of one-dimensional and three-dimensional piping models and their time history analysis results are presented. In the time history analysis, we used the Ramberg-Osgood model and the EAB model as the EAB hysteretic loop. The EAB model is the hysteretic loop that is obtained by the beam theory using the bilinear model as stress-strain characteristics. It was confirmed that the analysis results agreed well with the test results.

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The dynamics of a piston-slipper system in a hydraulic piston pump with a swash plate is complicated due to the hydrostatic cyclic pressures on piston head, reactions from lubricants of some bearing supports and the centrifugal loads. The basic equations of motion of this piston-slipper system are formulated in this work using the model of 10 D. O. F. and 2-mass system, and a general program to solve the dynamics of this kind of system has been developed using the Newmark-β method. In order to evaluate the applicability of the system, numerical analysis of motion of atypical piston and slipper system has been performed, and compared with the experimental analysis, satisfactory concordance has been obtained Next, the standard high-speed, high-pressure model on the market was analyzed and compared with the higher-pressure and-speed model. Some useful results for the higher-pressure and higher-speed model were obtained.

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The principles of measuring rotor unbalance are described for balancing machines with active dynamic vibration absorbers. In this type of balancing machine, an active dynamic vibration absorber is used to eliminate the vibration of a test table on which an unbalanced rotor is driven to rotate. The unbalance of the rotor can be identified accurately from the motion of the absorber mass when the table does not vibrate. Three methods of eliminating the vibration are presented. One of them is to use the absorber as an undamped dynamic vibration absorber. The application of the theory of output regulation is another method. The other is to apply repetitive or periodic learning control theories. In the experiments, the last method is adopted. The measurement results demonstrate that this method is suitable for precies measurement of rotor unbalance.

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Large-scale model experiments were carried out to examine the feasibility for practical use of a hybrid mass damper with convertible active and passive modes using a cylindrical linear induction motor. This mass damper can function as an active one to control relatively small vibrations of tall buildings caused by winds and weak earthquakes, and can also function as a passive one against strong earthquakes. By using the linear motor as an actuator, the mass damper can perform the mode switching simply by turning the power off and on, although its power efficiency is worse than that of dampers using normal AC servomotors. Shaking table tests were carried out for a one-dimensional experimental model having a 4.3 t moving mass equipped with two linear motors each of 7.6 kW capacity. Through the tests, validity of analytical models for the active mode, the passive mode and the mode switching was confirmed. Simulations were also carried out to predict performance of the experimental model when it was applied to a 7-story building, and showed excellent performance against strong winds and moderate earthquakes.

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This paper describes an approach to controlling the vibration of flexible structures based on the power flow concept. μ-synthesis is used to design a controller that minimizes power flow and retains robustness for unmodeled dynamics. The designed controller is evaluated by numerical analysis and experiment, and it is found that the proposed approach can be wed to design a controller with good performance and robustness. It is shown that the μ-controller realizes better vibration properties than an H_∞ controller does.

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This paper describes the influence of the nonlinear characteristics of a magnet, which is expected to have a large influence on levitation performance of a maglev vehicle with mechanical air gap control. The effect of nonlinear characteristics of magnets on levitation performance, which is expressed by the guide wheel load of the vehicle, is initially analyzed from a static point of view. Numerical calculation and experiments using test vehicle are carried out to show nonlinear effect of the magnet on the levitation performance. The dynamic levitation performances are analyzed by a simulation study with 3 DOF and 17 DOF vehicle models. The simulation results show that the unstable rolling motion of the undercarriage is caused by nonlinear characteristics of magnets if a low control lever ratio is set. It is also shown that the deterioration of levitation performance caused by nonlinear characteristics of magnets is suppressed by a large control lever ratio.

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A new design process is developed for a flexible printed circuit (FPC) that picks up the head signals of a magnetic disk unit, and can optimize the FPC loop shape. The head can be positioned by consideration of dynamic reaction force of FPC. In the process the dynamic treatment of a FPC is regarded as a vibration structure. A calculation method is proposed equivalent bending rigidity (EI) of a complex FPC. The evaluated EI is further used to determine the influence of the dynamic reaction force. A dynamic FEM model and the servo model are used to determine the residual vibration force just after bang-bang seek. Evaluated dynamic reaction force agrees very well with the experimental data. It is clear that the dynamic reaction force is very similar to the shock spectrum of a single degree of freedom. The optimization of FPC jointed to carriage and base for both ends is achieved. The optimum shape is very close to semicircular.

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A serial printer using a synchronous belt in the print-head carriage system generates a vertical striped pattern in the printing image. This is known as jitter and can be considered to be caused by vibration of the print-head carriage system. In this paper, as the first step in the study of jitter, a method of numerically evaluating jitter is proposed and a vibration experiment of the carriage system carried out. An image scanner is used to digitize the printing image and a relative brightness fluctuation is introduced to express jitter. The frequencies and the magnitudes of jitter are clarified by spectrum analysis. The results of the vibration experiment shows good coincidence between the vibration velocity of the carriage system and jitter. It is found that all vibrations in the length direction of the carriage system appear on the printing image as jitter.

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To fully utilize optical fiber cable characteristics; such as low loss, small outer diameter and light weight, a cable is installed in the longest possible unit distance. To implement this, some pullers are installed in intermediate manholes to distribute the cable pulling force. An optical fiber cable pulling system has been developed which measures loading tension on the cable using tension sensors and automatically controls pulling velocity so that the measured tension retains a proper value in the optical fiber cable installation.

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In this study, a tracking control problem of a 2-link tendon flexible arm is discussed. First, the equations of kinematics and motion are derived by a static deflection model. From kinematic and dynamic equations, the relationship between tip trajectory and joint input torque is derived, and the condition of the tracking control is considered. Then a trajectory controller of the tendon flexible ams is designed for tracking a linear or a circular trajectory. The simulation result shows that the proposed method can track an arbitary trajectory except for the singular position. It also shows that tendon mechanism has better tracking precision than the normal shaft driving one.

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A variable viscous damper using electrorheological fluid (ERF) is developed to suppress torsional vibration of an industrial robot. An integrated system consisting of a drive motor, harmonic drive, linkage and ER damper is measured experimently and found to be able to reduce antiresonance / resonance phenomenon by increasing the viscosity of the ER damper. A position control system which is based on the conventional semiclosed control and this new ER damper is analyzed, and the relation between the ER damping coefficient and the bandwidth of the system is discussed using the pole assignment technique. It is shown that the ER damper provides both vibration suppression and disturbance rejection.

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This paper deals with the robust control problem of a master-slave manipulator for uncertain objects. The uncertain object is assumed to be a spring-damper system described by a linear model with bounded parameter perturbations. A feedback controller is obtained such that the closed-loop system is robust exponentially stable and the L₂ gain from operator input to the penalty signal is less than a given level in the presence of parameter uncertainties. Experimental results are given to show the usefulness of the presented controller.

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The uninterrupted supply of electric power requires that high-voltage power distribution maintenance work be done in a live-line state, and for this purpose a manipulator for power distribution line work has been developed that allows an operator to work by remote control. The manipulator must be light weight and have high output, because it is installed on the relatively unstable end of an insulated crane boom of a "cherry picker" truck and must handle heavy objects such as power distribution machinery and materials. Under such conditions, a hydraulic drive system has more advantages than an electrical drive system, but from the standpoint of control performance, a hydraulic manipulator has some characteristic problems not found in an electric manipulator. The stiffness is also low in the hydraulic driven manipulator because most of it is made of plastic in order to ensure electrical insulation performance. In this research we are studying the positional precision of the end of the arm in terms of robustness with respect to changes in the system parameters of a 6-link hydraulic manipulator that has such unstable characteristics. In particular, cooperation among the various axes becomes important for improving the positional precision, and a sliding control method is applied and evaluated by an independent servo-system for each joint. As a result, it was verified by experiment that robust, stable positional precision can be achieved although undesirable chattering occurs. Chattering is effectively eliminated by smoothing out the control discontinuity in a thin boundary layer neighboring the switching surface, however it involvesa trade off between tracking precision and robustness to unmodeled dynamics.

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In a peg-in-hole task, the task-performable areas are graphically evaluated using gray scales from the manipulability and DMA (dexterity measure for assembly) in the areas reached by a manipulator. The DMA is represented as relation between a unit value of joint angular errors allowable in the task and a unit value of joint angular errors of the manipulator. The DMA consists of a DMGC (dexterity measure for geometric conditions) and a DMFC (dexterity measure for force conditions). These measures relate to task conditions, including both compliance of a remote center compliance device (RCC) and compliance of the manipulator joints. The task conditions are represented as physical models. The manipulability measure is used to check the kinematic accuracy of the manipulator. A graphic representation enables us to understand easily the relation ships between the task and the kinematics of the manipulator, since it integrates the DMA and the manipulability measure in the reachable areas.

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A state observer which rejects periodic disturbances is proposed for a discrete-time linear system. An observer-type compensator based on the above theory is newly developed, which rejects the influence of periodic disturbances from the output of a controlled system. This compensator cancels the periodic disturbance with the aid of asymptotic estimation of the periodic disturbance itself. Although this compensator does not estimate the real state, it is verified that this compensator can be used in system control as well as observers, and hence realizes an input/output performance characteristic equivalent to that of a servomechanism designed for the no- disturbance condition.

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Adaptive control systems based upon the command generator tracker (CGT) approach have attracted considerable interest because of the simple structure of their adaptive controllers. To date, the procedures for designing them have mostly been discussed with respect to the continuous-time case. As to a discrete-time adaptive control system based upon CGT, less attention has been paid to the feasibility of the control algorithm. This paper deals with the stability of a discrete-time adaptive control system using a new practically, applicable digital algorithm. The performance of the control method is evaluated through experiments with an electromechanical servo system using a DC servomotor.

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The electronic speed controller has used proportion al integral derivative (PID) control method. However, PID Control method is short of consideration about compensation for robust stability and drawing out sufficient control performance. Therefore, we have applied H-infinity control to this system in order to design a control system considered robust stability and control performance. This paper presents an application of H-infinity control to an electronic speed controller for a gasoline engine, and examines treatments of torque disturbance and how to design a suitable H-infinity control system by means of simulations and experiments. The results of both simulations and experiments show that the torque disturbance appropriately assumed as the input disturbance and that the input disturbance control problem of H-infinity control is suitable for an actual electronic speed controller.

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This paper deals with the acoustic power minimization problem from the viewpoint of an active noise and vibration control. This paper places a particular emphasis on the phenomenon in which the acoustic power output of the control source under optimal conditions always becomes zero. It is found that the acoustic radiation impedance at and around the control point source becomes reactive under the optimal condition, and hence power output of the control source results in null. It is also shown that the reactive acoustic intensity dominates even in the vicinity of the primary source in order to impede the sound radiation from its source. In active vibration control, the power flow in terms of a control force, applied directly to a vibrating structure in an effort to attenuate the radiated sound is found to be zero. Under the optimal condition for minimizing the total acoustic radiation power, the effect of the reactive sound field outweighs that of the active sound field significantly over the vibrating plate.

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It is frequently important in engineering to analyze complicated acoustic problems in the case of a large number of small holes at an interface boundary. A muffler used for reduction of exhaust noise is a typical example of such a case. The boundary element method could be applied to such problems, but this analysis would require a huge number of boundary elements to obtain accurate results. To circumvent this difficulty, we propose a new boundary element method which can be applied effectively to 3-D acoustic problems with small holes on the interface boundary, governed by the Helmholtz equation. An attempt is made to improve the accuracy of the method previously proposed by us. Some improvement in computational accuracy is demonstreated through numerical computation of two sample problems.

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In this paper, a new technique to measure the instantaneous three-dimensional velocity of flow is introduced. Velocity vectors of flow are obtained by measuring the three-dimensional movements of tracer particles suspended in the fluid. By introducing a refractor on the TV camera lens, the image of the tracer particle is displaced corresponding to the distance between the TV camera and tracer particle. Upon rotating the refractor at high speed during the TV camera exposure, spiral streaks of moving particles appear on an image since the circular shift is added to the movement of tracer particles. Each spiral streak contains three-dimensional information on the moving particle since the size of the streak is inversely proportional to the distance of the particle from the camera. The location and size of the spiral streak in the image are related to the three-dimensional location of the particle, and the pitch and size variations of the streak are related to the three-dimensional velocity of the tracer particle. We applied the technique to the measurement of three-dimensional water flow in the test tank and obtained satisfactory results.

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A human vision model is formulated in this paper, considering that line drawings are not limited to projection only from a polyhedron. To select a line drawing which can serve as an elementary picture for human stereo vision, we performed a psychological experiment. The model was proposed based on the experimental data to describe a property of human vision. Several examples were solved to validate the proposed model. The image-irradiate equation given by the Poisson equation is solved to reconstruct a face. Numerical simulation demonstrates that faces can be recovered precisely by considering the shading on the picture. This successful procedure involves solving the Dirichlet problem of the Poisson equation, specifying the boundary condition which is produced by the reconstructed edges. Numerical examples involve a drawing comprised only of lines, and a line drawing with shading.

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In order to devolop an "Active Human Interface" that realizes emotive interactive communication between machine and human being, we have been investigating the recognition of human emotion from facial expressions. This paper deals with the machine recognition method of 6 basic dynamic facial expressions. First, we carry out psychological recognition tests of 6 basic dynamic facial expressions for 3 subjects to clarify the characteristics of human dynamic recognition of facial expresions. Then, we construct a recurrent neural network (RNN) equipped with a feedback layer and a differential input layer for developing the machine recognition method. Using the dynamic data of each facial expression and the human recognition result for 2 subjects, we train the RNN and recognition tests are performed by inputting the dynamic facial data of one subject not used in training the RNN. By comparing the results obtained with RNN to those of human recognition, the RNN is found to perform very similar dynamic recognition to that exhibited in human recognition of facial expressions.

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In this study a color 3-D range finder operating at the video rate has been developed for the purposes of industrial and welfare application. The range finder with simplified circuits discriminated eight colors through classifying the R, G, B signals from binocular cameras into high and low brightness levels. The corresponding color boundaries were determined by comparing binarized brightness levels, thereby enabling the derivation of an accurate parallax signal. This finder was applied to three-dimensional measurements of distances and dimensions. The influence of color combinations on the distance acquisition rate was examined. The results showed that the finder is useful as a practical device.

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This paper describes a marking robot which leaves a specific mark at the fitting position for various apparatus on the ceiling boards in large buildings. We have developed a prototype system and carried out an experimental assessment. The robot can move autonomously and locate itself at desired locations. Then it can draw specific figures on the ceiling board. In order to accomplish such jobs, the mobile robot is carrying a Self-Position Measuring System (SPMS) and a Marking System (MS). The SPMS measures the bearings of the surrounding pillars, so that the calculation based on triangulation can give the coordinates of its own position. The MS is composed of the X-Y-plotter-like drawing equipment and the lifting mechanism elevating it to the ceiling board. Experimental results proved that this system was able to mark a square and a circle with an error of ±l0 mm.

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This paper describes the characteristics of journal bearings lubricated with a mixture of refrigerant and lubricating oil under similar operating conditions to those in compressors for household refrigerators, The purpose of this study is to clarify the difference in journal bearing characteristics between lubricating oils in which refrigerants HFC-134a and CFC-12 are dissolved, and the effect of refrigerant solubility in the oil on the bearing characteristics. The combinations of refrigerant and oil used in this study were H-FC-134a/ester, CFC-12/mineral which had high refrigerant solubility, and HFC 134a/alkyl benzene which had low refrigerant solubility. Experiments for these combinations were performed by using a journal test machine under different conditions of pressure and temperature. In conclusion, (1) in the fluid lubrication zone, there is no significant difference in journal bearing characteristics between the combinations of HFC-134a/ester, CFC-12/mineral, and HFC-134a/alkyl benzene, and (2) in the boundary lubrication zone, HFC-134a/alkyl benzene has better journal characteristics than HFC-134a/ester and CFC-12/mineral because of lower refrigerant solubility.

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A study on the force transmission from a drive pulley to a belt is presented. The problem of belt slip on the drive pulley is often encountered when small slips initiate at the vanishing point of belt contact with the pulley and extend to the entire range of contact. This phenomenon cannot be satisfactorily explained by the conventional theory. Taking into consideration the elastic deformation of the lagging and the belt cover rubber which exists between the pulley and the belt cord for transmission of the driving force, the formulas for belt tension and the "slip ratio" which shows the range of the small slip are proposed for the design of the belt conveyor

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This work concerns the development of a manufacturing technique for three-dimensional micromechanical parts. The micromechanical parts or micromolds are made by writing with a focused UV laser beam on the surface of a liquid photopolymer. At this time the irradiated portion of the liquid photopolymer becomes solid. Three- dimensional solidified polymer structures are then obtained by stacking the two- dimensional polymer structures. In this paper we theoretically examine the effect of absorption of light in a photopolylmer and exposure factors such as beam power and writing speed on the shape of the solidified polymer. The optimum conditions for three-dimensional micromechanical parts are also determined. Using these conditions, three-dimensional micropolymer structures are formed. The shapes obtained by stacking two-dimensional polymer structures are also examined.

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Five rolling contact fatigue tests, Tests (1)∼(5) were conducted. In Tests (1)∼(3), in the first step, when a fatigue crack was initiated on the surface of a follower, the test was stopped. In the second step, the rotating direction was reversed in Test (1), the roles of follower and driver were exchanged in Test (2), and the same test as the first step was continued in Test (3). In Test (3) the original crack grew to a pit. On the other hand, in Tests (1) and (2) the original crack immediately ceased propagating. In Tests (4) and (5), mating with a harder roller, a softer roller was used as the follower in Test (4) and as the driver in Test (5). A typical arrowhead pit appeared in Test (4). In Test (5), however, surface damage substantially different from a typical pit was generated. Based on the experimental results, the mechanism of pit formation was analyzed by 3-D crack analysis, in which the effects of frictional force on contact surface and oil hydraulic pressure on crack surfaces were considered in particular.

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A face gear can be cut with a pinion cutter using a simple attachment fitted to an ordinary gear shaper. Assemblage and adjustment are easy, and the face gear is sufficiently practicable as a substitute for a bevel or hypoid gear. However, the limited face width is the disadvantage of a face gear, because the outside diameter is limited by the narrow tooth edge, and the inside diameter by the undercut and involute interference, This study was designed to effectuate drastic relaxation of the face width limitation by introducing a coefficient of transverse shift as a new design variable for a face gearset. In the lst report of this study, strict theoretical analysis was undertaken for the engagement of the generalized profile-shifted face gearset. A large number of synthetic limit diagrams were prepared on the basis of the theoretical formulas obtained, and the applicability was examined. The results confirmed that the introduction of a coefficient of transverse shift was very effective for the relaxation of the face width limitation for a face gearset.

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This study was designed to effectuate drastic relaxation of the face width limitation by introducing a coefficient of transverse shift as a new design variable for a face gearset. In the 2nd report of this study, a design system was formulated and programmed using the theoretical equations and synthetic limit diagrams derived and tested in the lst study Contact line diagrams were prepared using the contact lines calculated from the programmed data. The applicability was examined. Then, a large number of design computations were carried out for the design system developed. The results confirmed that, as theoretically expected, the face width of a face gear could be increased by introduction of a coefficient of tnansverse shift. The gears manufactured for trial are smoothly engaged. The practicability is thus verified.

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In this study, an exact vibration model for helical gear pairs is developed assuming no spacing error and no shaft run-out, in consideration of the nonlinear tooth separation phenomenon. In this model, a simple modified stiffness function, including the effects of tooth numbers and addendum modification coefficients, is proposed for a helical involute tooth pair. The validity of this new stiffness function is verified by comparing its results with those of theoretical calculation and experiment. The rotational vibration of helical gear pairs with comparative narrow face width is simulated clearly on a 16-bit personal computer in Fortran by using the finite difference method, The total contact ratio including transverse and overlap contact ratios, is changed in the range of 1 ≤ ε≤ 3. As a result, the simulated vibration time waveforms and their frequency characteristics agreed precisely with Umezawa's calculation and experiment. The simulator is also used to clarify the effect of shaft deviation upon the vibration of helical gears.

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Based on the new stiffness function of a helical involute toooth pair proposed in the lst report, a method for obtaining the equivalent profile error of various tooth surface errors, including the effect of tooth deflection due to load, is proposed in this report. All of the cutting and assembly errors and the tooth surface modification are considered as various tooth surface errors on the plane of action. By considering the load, stiffness and tooth surface error predicted by a static meshing analysis, the actual average static deflection of a gear pair can be obtained. In the case of a light load, the actual deflection of the gear pair with side bearing error is larger than that with no error. Moreover, the equivalent profile error and the vibration due to the pressure angle error, shaft deviation and crowning modification, are calculated in Fortran on a 16-bit personal computer. The decrease in resonance frequency due to side bearing tooth surface errors is clarified. This phenomenon is caused by the increase of actual deflection as stated in the previous static analysis. Lastly, the influence of the above errors on the vibration is investigated, and the relationship between the vibration and the error's magnitude is shown.

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This paper derives new equations for calculating the efficiencies of differential gear drives using simple laws based on mechanics, When the new equations are used, the efficiency for speed reduction is lower than that for speed increase, in most cases. This is completely opposite to the case of the results obtained from the earlier equations. The reason for this is clearly shown by analyzing the power flows used for deriving the equations. It is found that the power flows used for deriving the earlier equations do not satisfy the boundary conditions due to an assumption which is unconsciously introduced in the process of deriving the equations. Numerical calculations are conducted and differences in the efficiencies are shown in the case of representative differential gear drives.

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This paper presents a study on the maximum contact stresses of WN (SymMarC and Haseg SymMarC) and involute gears. The contact stresses of WN and involute gear teeth with various dimensions were calculated under different applied loads. The relations between the applied load and maximum contact stress and the effects of center distance, helix angle, number of teeth and addendum modification on the contact stresses of WN and involute gear teeth were determined to a considerable extent. The maximum contact stresses of WN gears were found to be relatively larger than those of involute gear teeth for smaller applied load, but to become relatively smaller than the latter for larger applied load.

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This study aims at developing a technology that the tooth flanks of a hardened gear can be mirror-finished in a short time. We propose a simple gear finishing method using a helical gear made of nylon for the lap. This method is a lapping in which the work gear is meshed with a helical gear set at a helical angle. analogous to shaving. The gear flanks are loaded by means of braking the following shaft. Lapping fluid is splashed between the gear teeth as the gear rotates. Laps made of soft nylon are easy to manufacture, and their accuracy will hardly influence the accuracy of lapped gears. The features of a new lapping machine and the accuracy of lapped gears are described.

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The aim of this research is to develop a CBN (cubic boron nitride) finishing hob that can cut medium-and high-hardness gears accurately and efficiently. This paper deals with the improvement in the finished surface roughness of gears that have medium hardness, achieved as a result of using cutting fluid. Cutting tests with a CBN fly tool are carried out. The influence of dead metal on the cutting edge on the roughness of the finished surface, and the cutting fluid effects on the improvement of it are elucidated. In order to determine an effective cutting fluid for improving the roughness of the finished surface in hobbing, the viscosity of cutting fluid and the content of chloride and sulfide are investigated. The effect of water-soluble cutting fluid is also studied. The results show that the surface roughness is reduced to 60-80%, compared with the surface roughness in dry cutting, by using the appropriate cutting fluid, and the surface finished with a CBN tool is smooth compared to finishing using other tools.

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The most fundamental cause of machining error is kinematic error due to the structure errors in machine tools. In this paper, thirteen structure errors are defined for three typical types of five-axis machining centers, which are the tool-tilting type, the work-tilting type, and the tool-work-tilting type. The structure errors are further categorized into alignment errors and adjustment errors. The number of alignment errors, which are essential static errors between adjacent elements in the machine tool and can be only corrected by reassembling the structure, is dependent on the type of machining center. The influence of structure errors on the machining accuracy is evaluated through the computer simulation by applying the National Aerospace Standard. When the machine tool of tool-tilting type is used for machining, the structure errors mostly affect the shape of the machined part. On the other hand, the structure errors in the work-tilting type mostly cause dimensional errors of the machined part.

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Melamine-bonded wheels with diamond fine grains and pore structures were developed for smooth and mirrorlike finish of die materials. White fused alumina (WA) grains were added into a grinding fluid to enable self-dressing of the wheel by rolling WA grains between the wheel and a work material. The effect of WA grains on the self-dressing was examined through the measurement of grinding force, removal rate and wheel wear rate; that could be obtained under the process of surface grinding of a sintered tungsten carbide. It was clarified that the removal rate and the wheel wear rate could be controlled by varying the WA grain size and grain density in the fluid. Namely, the wheel wear was generated actively in proportion as the WA grain density In the grinding fluid became high. Also, it was confirmed that the wheels wear rate overcame the removal rate in the case that the WA grain size in the fluid became larger than 30% value of diamond grains that were contained in the wheel.

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The purpose of this study is to improve the machined surface roughness and machining efficiency of fine ceramics by in-feed honing. The results obtained are as follows. The honing force shows a considerable change which corresponds to the difference in the surface generation phenomenon. Transient honing time shows a tendency to decrease as the fracture toughness of the workpiece decreases. In the honing of brittle materials, a very small interference depth between the cutting edge and workpiece makes the work surface have better roughness characteristics. In order to improve the honed surface roughness, in the case of honing with a metal-bonded stick, it is effective that the cutting surface of the honing stick be dressed by a etch method after truing with a diamond wheel grinding.

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