A new nonlinear steady-state calculation by substructure synthesis is presented for large-order rotordynamic systems with a few nonlinear elements, which is considered popular in actual rotating machines. In this paper, linear dynamic and static structural relations are reduced to small degrees of freedom on nonlinear elements such as nonlinear bearings. Using discreet Fourier transform (DFT, also using FFT), and the Newton-Raphson method, harmonic balance for this reduced nonlinear system can be obtained as efficiently as for a simple rotor system. As examples, the effect of a friction damper on a turbine blade model and nonlinear unbalance response of an actual turbine rotor supported by squeeze film dampers without centering springs are discussed.

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Previous papers discussed a method for identifying model parameters of a vibration system by means of a non-linear least square minimization procedure of an evaluation function which consists of the difference of natural frequencies, mode shape coefficients of natural modes between the measured data and the data calculated from the estimated model parameters. The method using the previous evaluation function tends to necessitate a large number of iterations. This paper proposes a method using a new evaluation function for the purpose of decreasing the number of iterations and steadying convergences. It contains scalar values which evaluate the similarity of mode shape between the measured natural mode and the calculated one of each order, instead of each mode shape coefficient of natural modes. The effects of using the above-defined scalar values are discussed. Numerical models are examined to verify the efficiency of the method using a new evaluation function.

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A boundary element method is developed for the free vibration analysis of a rectangular plate with a slit. The formulation employs a fundamental solution of a static problem of a plate and this creates not only boundary integrals but surface integrals as well, owing to the presence of an inertia force. Thus the discretization consists of boundary elements as well as interior elements. The boundary and interior are divided into constant elements, and all integrals are solved analytically. The method is applied to square plates having a slit, and the natural frequencies and the modes of vibrations are calculated numerically.

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This paper deals with the free vibration of twisted cantilevered beams having arc-sections experimentally and analytically. Test specimens were made of the alumimume alloy pipe. Natural frequencies and modes of vibration were measured from the free vibration tests. Analytical investigations were also done by using the Rayleigh-Ritz method. The comparison shows that a good agreement exists between experimental and analytical results both in natural frequencies and mode shapes. Frequency parameters and modes of vibration for typical twisted cantilevered beams with arc-section are analyzed by using the method proposed and effects of pre-twist and center angle of the arc-section on frequency parameters and modes of vibration are investigated.

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An analysis is presented for the free vibration of a cross-ply laminated circular cylindrical shell. For this purpose, the governing equations and the boundary conditions of vibration of the shell are derived according to a first-order shear deformation theory (FSDT) by applying the variational principle, and the equations are written as a coupled set of first-order differential equations by the use of the transfer matrix of the shell. Once the transfer matrix has been determined by the numerical integration of the transfer matrix equation, the frequency equations are derives in terms of the elements of the matrix. The method is applied to cross-ply laminated circular cylindrical shells and the natural frequencies and mode shapes of vibration are calculated numerically, and the effects of the boundary conditions and lamination parameters on the vibration are studied. Furthermore, the results obtained from the present theory are compared with those obtained from the classical thin shell theory (CTST) and the approximate first-order shear deformation theory (AFSDT).

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This study examines the fundamental characteristics for a flow-induced vibration of shell-type long-span gates which have a gate front consisted of vertical and inclined weir plates. The shell-type gates possess two freedoms to vibrate in the streamwise and vertical directions due to their bending flexibility. Both streamwise and vertical vibrations couple well each other through hydrodynamical forces acting on the weir plates, thus resulting in a severe self-excited vibration. A two-dimensional model test for a shell-type long-span gate under small gate-openings was performed and a previous study reported the experimental results in detail. Here, the obtained results for the vibration frequency, the added mass of water and the dynamic press-shut gate trajectories are carefully studied. Moreover, the self-excited vibration mechanism is studied and the self-excited vibration possibility of Shell-type long-span gates under practical uses is examined. Finally a design criterion for dynamic stability is presented.

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This paper deals with a self-excited vibration of a rotating Mindlin circular plate subjected to a concentrated frictional force exerted on its outer circumference. The authors discussed the internal resonance of the circular plate with imperfections. As typical of the imperfections, they considered the additional masses for the circular plate without imperfections. It turned out from the method of multiple scales the (1) the imperfections have a tendency to suppress the occurrence of the self-excited vibrations of not only single modes but also internal resonance, (2) the optimal arrangement of the masses to quench the internal resonance between two modes is the same as that for the lowersingle mode, and (3) the resulting vibration shows the waveforms with beat, and the waveforms of the higher mode are affected by the lower mode in the internal resonance.

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An investigation was carried out to elucidate the natural vibrations of the ball bearings. In this report, out-of-plane natural vibrations on the outer ring of a loaded ball bearing were studied. A point on the outer ring of the ball bearing under a thrust load was excited sinusoidaly by a shaker. The axial responses of 34 points on the outer ring were measured by an accelerometer. Analysing the axial responses, the modes of out-of-plane natural vibrations on the outer ring were obtained. From the experimental results, theoretical analysis and considerations, existences of the out-of-plane natural vibrations on the outer ring of a loaded ball bearing were clarified, and frequency expressions for the out-of-plane natural vibrations on the outer ring were derived. Moreover, the remarkable accuracy of the frequency expressions was demonstrated.

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The main purpose of this study is to design a vibration reduction system of a machine subjected to random excitation. The optimization criterion in the design is to minimize the mean square displacement of the machine to the force excited by white noise. We also propose a design procedure of a vibration isolation system to reduce the force transmitted from the machine to the ground or supporting foundation. The vibration reduction/isolation system was assumed, to have a single degree of freedom. Including the extra degree of freedom caused by the elasticity of the ground, the total system has two degrees of freedom. This paper presents expressions and computational graphs which show the optimum tuning and damping parameters for a linear system with two degrees of freedom. The optimum parameters were tested on a vibratory model. The experimental work shows that the present analysis is useful for reducing the vibration induced by random excitation.

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In this paper, the growth mechanism of corrugations on rolling surfaces caused by plastic deformation has been examined by experiments. Using an experimental machine with the rolling contact of two wheels, whether the corrugations grow or diminish has been determined by changing the natural frequencies of many-degrees-of-freedom vibration systems. In the case of a system with two degrees of freedom, rigid support of the roller rig leads to long-wave corrugation due to the first coupled natural frequency. On the contrary, soft support introduces short-wave corrugation. Namely, the wave length and stability conditions of corrugations depend on the coupled natural frequencies. These conditions of corrugation stability gained by experiments agree with the theoretical calculations using models of a non linear self-excited system.

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The effects of in-plane force on the composite loss factor and natural frequency of a rectangular viscoelastic sandwich plate, which is composed of a core layer of viscoelastic material and thin elastic outer layers, are investigated. Assuming the vibratory energy dissipation to take place due to the shear deformation of the viscoelastic layer, the equation of motion and boundary conditions for a rectangular viscoelastic sandwich plate are derived from Hamilton's principle. The value of the composite loss factor of the sandwich plate increases as the in-plane compressive force increases, and decreases as the in-plane tensile force increases. Experiments have been carried out with a square sandwich plate with all edges built-in, subjected to no in-plane forces and to in-plane forces. Good agreement has been found between the experiments and calculations.

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This paper describes static test results of lead-rubber bearings using bolts for connection to the isolated superstructure and the foundation. The bearings used for the tests were 0.1- and 0.27- scale models of a 4900 kN rated load bearing which was designed for preliminary study of the seismic isolation bearings for nuclear facilities. The fundamental tests revealed various properties of the horizontal stiffness and damping obtained from the hysteretic restoring force loops. The repeated shear deformation tests showed that the bearings could keep their integrity through the 80-cycle repetition tests under a ±227% shear strain amplitude, and that the bearings had the fatigue resistance even against the 80-cycle repetition tests under a ±445% shear strain amplitude. The breaking tests by shear and compression for the bearings with and without the lead plug showed that the lead plug scarcely affected the breaking conditions of the bearings, and that the breaking shear strains were 518∼550%, corresponding to 1.14∼1.21m horizontal displacements in full size.

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Applying a torque to a pendulum at a natural position, we can bring it to an upright poisition by means of switching the direction of the torque at a suitable moment. In cases in which system parameters are known, under the condition of a small damping ratio, we can calculate the positions where the direction of the torque is switched. If the pendulum has a weight attached on its arm tip, system parameters change due to this weight. Thus, the number of switching and the switching time vary even if the same torque is applied. In this paper, we present methods which estimate a nondimensional torque in real time from positions and velocities of the pendulum using an energy diagram. Also, we give rules for switching the torque in order to bring the pendulum to an upright position.

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This research is concerned with the analysis of dynamic behavior and the stabilization of an electropneumatic valve positioner. When the valve positioner is surrounded by combustible gas, the electrical control circuit must be positioned far from the actuator by using the long pneumatic tube as a safety measure. However, if the length of the pneumatic tube exceeds a certain length, hunting will occur to the drive shaft of the actuator due to the time lag of the pneumatic pressure signals and the nonlinear characteristics existing in the system. First, the behavior of hunting and its generating conditions are clarified. Next, in order to prevent hunting, the compensator based on the Smith method is applied to this system and the effectiveness is certified. Finally, by experiment, it is ascertained that the introduction of the compensator makes it possible to stabilize the positioned.

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This paper considers an active dynamic vibration absorbing control system based on an adaptive pole assignment containing an internal model principle when the system is subjected to disturbances which are generated by a linear dynamic system. Here two kinds of design methods are considered. The first case is that all parameters of the plant and disturbance are assumed to be unknown, and the other case is that the parameters of the system are assumed to be known except for the disturbance parameters. The experiments demonstrate the effectiveness of the proposed method.

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As far as internal combustion reciprocating engines such as diesel engines are concerned, it is difficult to evaluate the seismic response because the axial vibration in the shafting system originates from torsional vibration, harmonic radial components of the gas and mass force, and seismic force. This paper presents a study on the response of a diesel engine used in an emergency power supply system during strong earthquakes. We conducted experiments to study the characteristics of nonlinear vibration using a shaking-table and calculated the axial behavior of the crankshaft on the oil film in the case of a shut-down and of a running engine. As a result, a good agreement was obtained between the calculated results and experiment ones. The proposed method of separating the response of seismic force from the other forces using coherency function was demonstrated to be effective.

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In this paper, the application of pattern recognition to the state discrimination of vibration systems is presented. Here, two kinds of nonlinear models are used for the recognition of nonlinearity. Procedures for the form of pattern vectors, and measurements of the distances between various patterns are illustrated. The feature parameter which is decisive for the discrimination is extracted based on the principal component analysis. Finally, the effectiveness of the discrimination is evaluated.

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From the past research, it is known that the maximum rms relative displacement of an elastoplastic structure subjected to a nonstationary input has a minimum value at an appropriate yielding level owing to the energy absorption. In order to obtain the optimal yielding level, this paper presents a sensitivity analysis of the yielding level for the seismic response of elasto plastic structures. Herein the sensitivity analysis is to find the sensitivity coefficient of the yielding level to the maximum rms relative displacement. By using these sensitivity coefficients, the probability distribution of the rms relative displacement can be evaluated from that of the yielding level of the structure. The seismic response of the structure was studied assuming that the restoring force characteristics of structure are represented by a simplified Clough model with the stiffness degradation, and the covariance of responses were computed by using an equivalent linearization technique on the assumption of narrow band response. The theoretical results were compared with those of digital computer simulation.

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This paper describes an optical detecting method of the edge position for measuring the profile and the dimensions of an object with a sharp edge. The measuring principle is based on the straightness of a laser besm and its diffraction properties at the edge of various shapes. The laser beam of Gaussian distribution is scanned parallel to the beam axis. When the laser beam is intercepted with a sharp edge at right angles, the transmitted beam power is reduced from the original total power according to the relative position of the edge to the beam axis. The detecting accuracy using a straight edge and a circular edge is analyzed and expressed by numerical solutions. A fundamental detecting apparatus for the edge position based on the measuring principle is presented and the basic performance of this apparatus is investigated. The results show that the detecting method proposed is appropriate for the noncontact detection of the edge position.

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The present paper deals with the description and estimation of the task state of a robot by means of fuzzy sets. It is necessary to describe the operation state in order to perform the work by a robot. But in the case where the environment of the operation is uncertain, it is difficult to describe the operation state quantitatively. In this study, we describe this operation state by means of fuzzy schemata which consist linguistically of fuzzy sets and estimate the state by using fuzzy pattern matching. The work object in this study is the peg-in-hole operation of two dimensions. The usefulness of this method is shown by experimental results.

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This paper describes vibration intensity measurements and the search for exciting sources in a gas heat pump using a two-channel vibration intensity probe. Vibration intensity vectors show the vibration energy flow originating from the flexural motion of beams and plates. To clarify the direction and amplitude of vibration intensity at each point of the structure, two determining methods, i.e., the vector composition method employing measurements obtained in two perpendicular directions and the method of least square fitting to the directional characteristic of the probe, were examined in this study. These two methods were discussed from the points of view of accuracy and expediency of the measurements. The vibration intensity measurement was then applied to determine the exciting sources in gas heat pump package panels. The result of noise reduction obtained by taking countermeasures expresses the utility of vibration intensity measurement for the identification of exciting sources in a machine structure.

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This paper presents a method for solving eigenvalue problems of various phenomena which are governed by the Helmholtz equation with an arbitrarily shaped outer boundary and a number of eccentric boundaries of arbitrary shape. In the analysis, the outer boundary condition is satisfied by means of the Fourier expansion collocation methed using the exact solution of the equation of motion. To satisfy the inner boundary conditions, the point restraints are added to the equation of motion, and the inner boundary conditions are satisfied by making use of a point-matching procedure. The equations for finding the eigenvalues are derived, and numerical calculations are carried out for cases of elliptical outer and a number of elliptical inner boundaries, and polygonal outer and a number of elliptical inner boundaries.

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A new method for the characterization of shock accelerometers is proposed. The reflection of the elastic wave propagating in a metal bar is used to generate input acceleration to an accelerometer. The elastic wave is produced by the collision of a projectile against the end of the bar and is detected with the strain gauges. The input acceleration is estimated using the one-dimensional theory of elastic wave propagation. The dispersion of the elastic wavefront due to the lateral inertia of the bar is corrected by using Skalak's analysis. The acceleration under which this method is carried out is higher than that of the conventional shaking method. The bandwidth of this method is wider than that of the conventional method because the input acceleration is of pulse shape.

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This paper presents a digital, simulation method by which the pressure pulsation response of a compressor-piping coupled system is analyzed in a frequency domain. In this method, a preliminary pulsation analysis is carried out to obtain the acoustic impedance of the piping system by using the ideal flow rate which is conventionally used. Then, a more precise flow rate taking the interaction into consideration is calculated by solving the governing equation which is derived from the state equation of the cylinder gas and the impedance of the piping system. Simple compressor-piping models are set up and analyzed to examine their suitability. Results by the present method are in good agreement with those of time history analysis by Runge Kutta integration. In addition, the effect of interaction is discussed, and it is found that the nondimensional value nωZV/γP is the parameter by which to evaluate the magnitude of interaction.

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In this paper, a new steering mechanism proposed by T. Emura is presented. This steering mechanism uses non-circular gears and has the capability of turning a carrier with a small radius. For the analysis of the steering mechanism, an idea of a virtual two-wheeled vehicle was introduced. As a result of the analysis by A. Arakawa, it was proved that the non-circular gear for steering is an elliptical gear. Besides, a method to apply this mechanism to wheeled robots such as carrier-robots in the industrial production lines was studied, and it was confirmed that the concept of the virtual two-wheeled vehicle is very useful for the design of the steering mechanism.

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This paper deals with experiments of the new steering mechanism which has been proposed in the first report. First of all, the elliptical gears for the steering mechanism were cut with the NC gear shaper developed by the authors, and the error of the rotational angles of the elliptical gears was measured. Then, the authors manufactured a wheeled robot for trial in order to confirm the usefulness of this steering mechanism and succeeded in controlling the wheeled robot using a TV camera for eyes. Moreover, they carried out fundamental experiments. These experiments proved that the new steering mechanism had high turning ability, and can turn the wheeled robot with the small radius.

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The concept of the wavelength of truck hunting, so far used exclusively in the field of lateral stability, can be used to express the minimum curve radius for a railway vehicle to negotiate curves without wheel flange contact with the rail Combining this idea with the calculation method of the wavelength of the truck whose axle boxes are suspended to the truck frame flexibly in the horizontal plane, railway truck designers can easily achieve the trade-off between hunting stability and curve negotiation, as stated in this paper.

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This paper presents a method to calculate the static bearing loads of multispan rotors by considering the nonlinear characteristics of oil film bearings. The initial alignment to be installed in the rotor is determined by minimizing the difference of the bearing load from the designed value and the stress of rigid couplings. To investigate the effects of the journal center displacement varying with rotating speeds, an actual turbogenerator system with four couplings and eight bearings is numerically investigated under initial and misaligned conditions. It is shown that the amount and direction of bearing loads strongly depend on rotating speeds under the misaligned conditions, but are negligibly small under the initial condition. To clarify the fundamental properties induced by the misalignment of the rotor system, the load direction effects on the journal center, unbalanced response and stability are investigated for a partial arc bearing.

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The stability of a single mass flexible rotor supported on three axial groove bearings was tested under a wide bearing load range. Running tests and impulse tests were performed under the bearing load which was controlled by electromagnets arranged at the center of bearing span. The linearized dynamic coefficients of bearing were calculated by considering hydrostatic effects of supplied oil pressure. And it was shown that the hydrostatic pressure decreases instability threshold speeds considerable. The experimental and calculated results were in a good agreement for high bearing loads, however, in a moderate agreement for light bearing loads. The experimental results also showed that the unbalance force decreases onset speeds of instability and the impulse force induces unsteady large vibrations of nearly half whirl of rotating speed.

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In this paper, we investigate the system dynamics of a one-link flexible arm affected by reduction gear friction. The natural frequency of the flexible arm lessens when the friction is larger and approaches that of a cantilever beam. The system damping changes with its natural frequency. Experiments were done in cases of both small and large frictions. The friction torque was nonlinear with viscous and Coulomb damping. Nonlinear and linearized calculations were shown to be in good agreement with experimental results.

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A new control method for the truss-type parallel manipulator is proposed by a neural network approach. The proposed method solves the problem of the inverse kinematics involving the kinematic redundancy with the multi-layered neural network model. This network model is prepared to install the kinematics relationship of the manipulator as well as the criteria functions for the configuration and motion control. A concept of the modular network is employed to cope with the hugeness of the network, in which a network module is prepared separately for each kinematic module. This modular network approach enables the network system for the configuration control to be adopted for various combinations of truss modules. Some simulation studies demonstrate the effectiveness and the potential capability of the proposed method.

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This paper investigates vibration control of a flexible rotor system which is a four-degree-of-freedom system. A H_∞ controller is derived such that unmodelled high-frequency dynamics are not excited, i.e., the spillover phenomenon is not caused to occur. Simulation results are presented to demonstrate control performance. In this paper, the four-degree-of-freedom system is reduced to a two-degree-of-freedom system. Although the control system is designed based on the reduced-order system, the 1st and 2nd modes are well-controlled and two ther higher modes are almost uncontrolled using the H_∞ control theory. As the result, the full-order system remains completely stable.

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This paper is concerned with the study of the stable holding and movement of an object by the grasping action of a robot hand. A control algorithm is proposed for manipulating the jointed-fingers hand while grasping an object and is applied to a hand with two fingers and four degrees of freedom developed especially for the study. In the experiment, an object on a plane is initially grasped by the hand and then moved along the restraining plane maintaining appropriate force. As a result, using the elastic-fingers unit with contact sensors, the present hand successfully moved the object while absorbing the outside force from the restraining plane.

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A conventional manipulator can drive its end point in three orthogonal directions, but it cannot change the direction and the rotational position of its arm. This paper discusses two methods: (1) the solid angle of the direction of the manipulator arm can be changed arbitrarily, which its end point remains steady in a narrow operation space and (2) the axis of the manipulator arm can turn entirely. On achieving the latter manipulator, one of the difficult problems is to make a bearing for supporting a pipe with a diameter of several tens of micrometers. A soluble plastic bearing is proposed. This paper discussed the limitations of making the bearing. The manipulator system is designed to easily be put on and off the pipette arm. The arbitrary direction changes of a microparticle are demonstrated by using two manipulators that pass the particle and rotate it alternately.

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A human being can ride on a log or a barrel and roll it to any place while maintaining a stable posture. This study aimed to realize such a motion by a robot. The authors have developed a barrel-riding robot which can ride on a cylinder. The robot is composed of a main body, double controlling arms, a wheel, and a cylinder. The cylinder corresponds to a barrel and is rotated by friction through the wheel which is mounted on the cylinder and supports the body block. The controlling arms are suspended from the upper end of the body. In order to stabilize the posture of the robot, feedback control based on the compound gravity center of the robot is applied to control the robot by the controlling arms. Furthermore, two control methods were proposed to drive the cylinder. Using the control methods proposed here, the driving control of the cylinder together with the postural control of the robot has been attainted.

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For moving on rough terrain, flying robots have more flexibility for adaptation, from the viewpoint of locomotion, than the conventional wheel, crawled and leg robots. This paper shows a modelling and control method of such a fliyng robot which consists of a main flying body and an attached manipulator. For smplicity, the manipulator has two degrees of freedom, while the main body has four ducted fans driven by electric motors. This paper mainly focuses on the attitude compensation control of the robot in the case where the motion of the manipulator on board causes the unbalance of the inertia momentum and where the attitude of the robot changes. Results of simulation and experiments on the ground are also shown in this paper.

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It has already been reported that when nylon (MC nylon) was filled with synthetic wax, the coefficient of friction decreased, and in the case of using such wax-filled nylon for gears, the wear of teeth was reduced, and the amount of gouging of the teeth roots by the top corners of teeth on matching steel gears decreased: accordingly, the change of pressure angle became less. In order to confirm whether phenomena such as these may also occur in polyacetal or not, gears were made with material having a small coefficient of friction by filling polyacetal with fluorine-containing resin, and trial operation was carried out. The wear of teeth, change of teeth profile and other properties were examined, and by comparing them with those in the case of polyacetal gears without filling, the effect of reducing friction was investigated.

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Since the abnormal wear at the dedendum of a gear made of plastic with a low coefficient of friction can prevented, polyacetal filling 10 % of fluororesin was used as a gear to reduce the coefficient of friction in the previous report. Although the gear showed high resistance to friction, it had shortcomings in that the price of the gear was high due to the high content of fluororesin, and fluororesin was hard to release from the mold. Mineral oil was, thefefore, substituted for a part of fluororesin in the polyacetal gear. This report presents the characteristics of the fluororesin and mineral-oil-filled polyacetal gear, such as the wear of the gear, the temperature of teeth and the change of the tooth profile determined by a practical test.

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In use, worm gears, the teeth of which are slid a relatively long distance, generate a large quantity of heat. It is impossible for plastics, which are inferior in heat resistance, to be applied for such worm gears for use in the transmission of high power without lubricants. The first report suggests that composite plastics filled with carbon fibers, solid lubricants, etc. are suitable as materials for worm gears. However, the worm gears made of the composite plastics are expensive. In this study, inexpensive plastics of nylon filled with mica fillers have been developed, and their application to worm gears has been examined. Increasing amounts of the mica filler cause the heat resistance temperature to become higher. However, they reduce the bonding degree of the nylon to the mica attained in the polymerization. Accordingly, when the composite plastics of nylon are used for the sliding parts, the wear resistance may be insufficient. The wear resistance, coefficient of friction, surface roughness, surface temperature, and worm gears of the nylon composite plastics with various amounts of mica filler have been examined to determine the optimum amount of the mica filler.

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A new method of calculating grinding-wheel profiles for finishing pinion cutters to shape spur and helical gears with an arbitrary profile is developed using the theory of the element removal method (ERM) previously proposed by the authors. In order to show the usefulness of this method, the profiles of the grinding wheel for finishing the pinion cutter (m_n=3) for Novikov gears with concave teeth are calculated numerically, and then the profiles of the pinion cutter finished by the grinding wheel are calculated. The difference (calculation error) between the given and the calculated profile of the pinion cutter was in the range of about 0.1μm before regrinding. Profile errors of the cutting edges after regrinding are shown in terms of the number of teeth, the helix and rake angles and the regrinding stock. The effective clearance angles of cutting edges, which produce some problems in gear finishing, are calculated from changes in the profiles of the cutting edges before and after regrinding.

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Involute gears were used for the reduction rears of hot-strip-rolling mills. The operating conditions are serious, and gear damage was frequently reported, presumably because of insufficient durabirity. Pinion stand gears of the rougher rolling mills in the Chiba 2nd hot-strip-rolling plant at this site also suffered from serious tooth damage, and a renewal project was undertaken. In the plan, a comparative study was made for conventional involute gear and W-N (Wildhaver-Novikov) gear which features high durability. As a result, W-N gears were introduced in 1985 for the first time as the plane-bearing-type reduction gears for hot-strip-rolling mills in Japan, and have been operating satisfactorily for 4 and a half years. In this report, the circumstances concerning the application of W-N gears, strength evaluation on the basis of root stress in actual rolling operation, and the operating condition are discussed.

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As test oils, two kinds of synthetic traction oils, two refined mineral oils (naphthene and paraffin types) and a conventional mineral oil were used for investigating the changes in the rolling contact fatigue strength (pitting limit) and the contact surfaces of low-hardness steel rollers with a hardness of HB≒190. In the case of pure rolling conditions, a high pitting limit of P_max≒1300 MPa(132.6 kgf/mm²=0.70HB) was obtained regardless of the kind of test oil, in most cases. However, the pitting limit decreased drastically when sliding with a specific sliding of about 20% was introduced to the rollers lubricated with traction oils having a high traction coefficient of about 0.1. Changes in contact surfaces of these rollers were appreciable and the grinding marks were hardly observed after running even when no pitting occurred. The duration of full EHL conditions between the rollers was longer than that obtained using oils with a lower traction coefficient of about 0.04. It was estimated that the changes in the contact surfaces are closely related to the reduction in the pitting limit although they are not caused by metallic contacts between the rollers.

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This paper describes the reasons why the lubricating ability of lapped surfaces is worse than that of scraped or milled surfaces, and method of improvement also is proposed. First, the permeability of the lubricant on the surfaces machined by some machining methods was measured using an optical flat. Next, oil grooves with 0.6 mm intervals on a lapped surface were produced by laser machining for improving the lubricating ability. Friction forces and rising values of a table from the guideway in each of sliding surfaces were measured using a prototype machine. As a result, the lapped surface improved by laser machining illustrated the possibility of a high-accuracy slider.

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Explication of the traction surface is one of the most important subjects for the traction-drive-type continuously variable transmission for automotive use. We made a half-toroidal CVT which could be installed in a 1300cc motorcycle engine, and performed a life test successfully at the fixed ratio. The temperature of the traction oil was 110-120°C. The maximum contact pressure of the traction surface was 2.15 GPa and the surface velocity was 24.2 m/s. After the life test, the shape of the disc and roller was measured. The traction surface roughness of the input disc was also measured and was observed by scanning electron microscope. Oil film thickness was calculated by Hamrock's formula in a life test condition. Owing to the observation of the traction surface and oil film calculation, we estimated that a 0.3 μm oil film could exist between two rolling elements of heavy traction drive.

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The effects of the geometry and size of the rollers and skew component on traction are experimentally studied on two-roller machines, in which experiments with the point contact are conducted for paraffinic mineral oil under the full EHL conditions. As the radius of a roller in the rolling direction is increased at constant bressure and rolling speed, a gentle decline in the maximum traction coefficient is observed. When the equivalent radius of the roller is equal, it is found that the same traction curve is obtained in both internal and external contacts. A traction curve is sensitive to variation in skew, that is, the initial gradient greatly decreases with a slight increase of skew angle. The simplified Eyring viscous solution already presented shows good agreement with the above observations.

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Stresses in elliptical-cross-section coil springs become small as compared to other springs used in practical machines at a certain aspect ratio. This article presents a simplified stress expression for designing the elliptical-cross section coil springs. The stresses obtained by the present design formula are compared with those obtained by numerical methods. It is ascertained that the present formula is applicable to design the elliptical-cross section-coil springs.

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This paper presents a method for designing a shape-memory alloy coupling between rods subjected to axial or torsional forces. The design formula is obtained by using the stress-strain relation. Since the coupling work is simple, the coupling has advantages for building members in dangerous zones. However, since the coupling force is not sufficient, it is disadvantageous for impact loads. To design coupling under consideration of impacts, this paper also discusses the transient response of the coupling due to various impact loads. Numerical calculations were carried out for some sample problems.

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A method for measuring the form error of spherical parts was developed in the previous report. The measured results showed that steel balls used as ball bearing assemblies usually had the form error of three or four undulations. In the present report, a harmonic analysis by the spherical function is introduced to evaluate the sphericities of the steel balls. Dimensional spectra have invariant values for each ball even if the measuring coordinate axes are changed. Steel balls which are sampled in various states of different finishing processes are measured, and the dimensional spectra are calculated. The calculated results show that the dimensional spectra of steel balls that are in the same state of the finishing process have the same values and that the 3rd-order spectrum has a tendency to be left behind selectively by the polishing process. Evidence has been given that the harmonic analysis by the spherical function is successful for evaluating the sphericity of steel balls.

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In this paper, two cutting methods for ceramic plates with elastic working are proposed. Both methods are applications which take advantage of the results of bending fractured brittle materials. In our experiments, ceramic materials such as alumina, zirconia, sialon, and others, were cut along precise cut lines by making notches on the surface of these ceramic materials before cutting. By using this procedure, we were able to produce cut surfaces that were precisely perpendicular to the surface of the plate, and in the exact position of the original notches. The significant characteristics of both methods are that the cutting was done without generating any dust, the amount of energy required was very small, and the time required for the cutting process was very short.

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A new method which utilizes an infrared thermal monitor for measuring the grinding temperatrue was proposed. With the proposed method, surface grinding temperatures of SiC, Si₃N₄, ZrO₂ and Al₂O₃ were measured. The influence of grinding temperature on the material removal process was investigated through the SEM observation as well as the analysis of the ground surface profile. It has been confirmed that the elevated grinding temperature changes the material removal process from the brittle fracture mode to the ductile mode.

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