Using dielectric elastomer (DE) makes it possible to achieve a highly efficient transduction from electric energy into mechanical energy, which translates into a considerable energy saving compared with other actuator technologies. Furthermore, its low cost, light weight, softness, and quietness make the actuator suitable for robots, sensors, motors, speakers, pumps, and smart materials. The generator mode in DE uses the actuator mode process in reverse, transforming mechanical energy originating from the physical deformation of the elastomer film into electrical energy. DE has several characteristics that make it potentially well suited for wave, water current, wind, human motion, and other environmental energy harvesting systems including high energy density allowing for minimal elastomer material quantities, high energy conversion efficiency independent of frequency of operation and non-toxic and non-corrosion-susceptible low-cost materials.

A roller bearing gets failure when it is used long term under heavy load. Flaking on the outer or inner surface of the bearing is a typical failure. Abnormal vibration caused by the failure is measured usually using an acceleration sensor in order to detect the failure. It is relatively easy to detect the abnormal vibration and to diagnose the bearing failure if rotation speed is high, but it is difficult if rotation speed is low. The paper introduces recent cases of diagnosis techniques and products especially for low speed rotation rolling bearings. Also a simple and practical diagnosis method which the author has developed using a jerk sensor is explained.

A large number of solid lubricants are used in machine elements for products of heavy industries. It's introduced about the solid lubrication techniques used for machine elements of a fan for boilers, a reciprocating compressor, a marine diesel engine, a jet engine and a space station by this article.

CNx (carbon nitride) coating is an attractive material due to low friction coefficient. However, our previous research reported that the wear resistance of CNx deposited by IBA-ED (Ion Beam Assisted－Electron beam Deposition) was insufficient. In order to overcome this problem, we deposited CNx with higher hardness and non-droplet using IBA-FAD (Ion Beam Assisted－Filtered Arc Deposition), and this film showed high wear resistance. We termed the new CNx as ta-CNx (tetrahedral amorphous－Carbon Nitride). More interestingly, ta-CNx showed higher wear resistance with higher N/C ratio regardless of hardness decreasing. Here we show the mechanical and the fictional properties of ta-CNx.

In order to decrease friction coefficient of DLC (Diamond-like Carbon) film by external action, we developed the method to apply electric discharge during friction. To realize electric discharge not penetrating DLC film, we made SUJ2 special ball which had two parts. One part was made for getting stable friction; the other one was made for making potential difference between two parts. In the case of friction between Si-DLC film and SUJ2 special ball in air, friction coefficient decreased to 0.04 instantly by discharging. But gradually friction coefficient increased, and finally it became as same value as Control's value.

Si containing Diamond like carbon (Si-DLC) is known to have a low friction coefficient in hunmid air atmosphere. The mechanism for its low friction coefficient, μ=0.05 has been suggested by Mori et al to be the formation of hydroxyl group at the sliding interface[1]. They further reported that Si-DLC can show μ=0.03 by same mechanism[2]. Recently, Si-DLC coatings are expected to show ultra low friction (μ<0.01) in oil. One of the promising way to further reduce the friction coefficient was reported by Choi et al, where oxygen plasma treatment is employed for accelerating the formation of transfer layer from Si-DLC to mating surface; μ in ambient was reduced down to 0.03[3]. In this research, we investigated the influence of oxygen bonding in Oxygen containing Si-DLC (a-C:H:Si:O) on its friction property against SUJ2 ball under oil lubrication.

Low friction and high wear resistance without lubricant is desired thinking of the widespread of friction condition. DLC(Diamond like carbon) coating is one of the material to obtain these properties. Among them, Ta-doped carbon nitride (CNx:Ta) coating is the most promising material, because it showed ultra-low friction (μ<0.01) in dry air. But the hardness of conventional CNx:Ta coating in our laboratory was only 1.6-11.3 GPa of nano-indentation hardness, and we need to improve the hardness for improving wear resistance. For the deposition of high hardness CNx:Ta coatings, we developed a dynamic mixing deposition method combining the filtered arc deposition system, nitrogen ion beam source and tantalum arc plasma gun. We deposited four kinds of DLC coatings, ta-C, ta-CNx, ta-C:Ta and ta-CNx:Ta. Nano-indentation result gave the hardness from 39.87(ta-CNx:Ta) to 44.98 GPa(ta-C). Friction coefficients of these coatings were same at the test with normal load of 1.0 N, but it varied at the test with normal load of 5.0 N, from 0.365 to 0.062. Also the wear differed in the test with normal load of 1.0 N, ta-C and ta-CNx:Ta coatings didn't peel off while ta-CNx and ta-C:Ta coatings peeled off. In order to know the effect of transfer layer on the friction coefficient, we did EDS analysis. The result showed that transfer layer of low friction coatings had more carbon and less oxygen than that of high friction coatings.

Diamond like carbon (DLC) has widespread applications in many fields because of its excellent properties. Recently, DLC is applied to machine parts as coating to reinforce the surface property. On the other hand, the use of polymer parts made of engineering plastics is increasing instead of metal ones because polymer is light, low cost and easily processed. It is expected in the future that the application of DLC to metal comes to be more frequent in order to further improve the sliding property between metal-polymer contact in sliding parts. For that reason, it is important to clarify the characteristic of friction between DLC and polymer. In this research, silicon doped DLC (a-C:H:Si), which is coated by plasma enhanced chemical vapor deposition (PECVD) on a steel disk (SUS304, JIS), was used as a mating material of sliding against Polyoxymethylene (POM). Friction tests were conducted in a roller-on-disk apparatus under dry condition, where the side surface of POM roller was contacted to DLC-coated disk. During the total sliding distance of 200 m, helium gas flow and helium plasma flow were irradiated. After irradiation, friction coefficient rapidly fell down to around 0.066 from 0.2 and was stabilized.

The present study describes friction properties of polymer overlay containing molydenum disulfide (MoS₂) fine particles formed on the aluminum cast alloy (AC8A) surface in lubricated condition. Poly amide imide (PAI) was employed as an overlay material and fabricated on the micro dimpled surface using a spin coating process. The overlay thickness was approximately 10 μm and the different layer structures of the overlay containing 10 vol.% of MoS₂ were prepared. The friction properties evaluated with a 3-ball on disc type testing apparatus showed that the friction coefficient of the overlay was low and stable from the beginning of the experiment in comparison with the case of non-overlay substrate. Moreover, the overlay with the thin surface layer containing MoS₂ showed quickly transition to the stable friction coefficient. This result indicates that the MoS₂ alignment in the surface layer became higher by the high-speed spin coating.

CNT is an elongated tube of nanoscale. It has excellent flexibility and thermal conductivity. The CNT film which is produced by the SiC surface decomposition method is referred to as "Vertically Aligned CNT film". This film has features such as vertical alignment, high directivity, high density and high adhesion. So that, it is considered to be able to acquire a high contact area ratio and high heat transfer coefficient by sandwiching this film between solid contacts. We observed the surface shape, using a laser microscope, AFM and FESEM. In addition, I found the relationship between displacement and contact pressure using a nanoindentation tester. Thereby I check the deformation behavior of the Vertically Aligned CNT film.

Recently, 1-by-1 coating equipment for DLC coating process, which replaces conventional mass-production way with a huge chamber, is strongly desired in terms of downsizing apparatus and space-saving. In order to achieve this purpose, ultra-high-speed coating tith deposition rate of aver 1000 μm/h, which is 1000 times larger that that (~ 1μm/h) of conventional method, is required. The deposition rate of over 1000 μm/h was already achieved with integration of gas blowing to substrate and high-density-plasma (ne~10¹¹ - 10¹³) in our previous work. However, the mechanism of enhancement of the deposition rate is not still clarified. In this work, we elucidated the mechanism while focusing on the relationship between impingement rate of gas to substrate and thickness distribution of DLC. We found that both distribution of thickness and impingement rate closely matched. Moreover, we suggested some radicals with higher sticking coefficient have something to do with above-mentioned ultra-high-speed coating.

In order to elucidate the competitive adsorption phenomenon of two-component system of oiliness agents, the adsorption behavior and the mechanical properties of adsorption films were examined by using QCM-D and AFM. Stearic acid (SA) and oleic acid (OA) were used as oiliness additives. The results of AFM indicated that the two-component adsorption films of LB film and SAM both consisted of three regions of SA region, OA region, and mixed region, which were structured hierarchically in nano-micro scale. The results of QCM-D indicated that the adsorption amount of the two-component solution was larger than that of the single-component solutions.

In order to improve the writing feeling and lifetime of ball points, the influence of a solvent and a resin on tribological properties were examined by SRV friction tests, which were performed as a simulation of the sliding contact between a ball and a ball bearing seat in a ball point pen. Two kinds of solvents (Oil A and Oil B) were used as base oil and three types of resins were used as additive. In the case of Oil A, the molecular weight of resin effected on the tribological properties. On the other hand, in the case of Oil B, that tendency was not confirmed.

Wood-derived nanocarbons (WNCs) were synthesized from wood powders by metal-catalyzed carbonization. Moreover WNCs were oxidized by a modified Hummer's method in order to introduce WNCs to oxygen functional groups which enhance them to adsorb on metal surfaces. The oxidized WNCs (oWNCs) were easy to be dispersed in water, and the oWNC dispersion in water showed a very low friction coefficient of less than 0.05 using steel plates and tungsten carbide (WC) balls with a load of 1.8 N. Wear in the friction tests was also found to be low due to formation of triboflims. The oWNCs were also dispersed in poly-alpha- olefin (PAO) and tribological property of the oWNC dispersion in PAO was investigated.

Electric field can control adsorption structure of ionic liquids on solid surface. There are, however, few report about the relationship between frictional property and adsorption structure in macroscale under the electric field applied. In this study, the effect of the electric field on a frictional property of ionic liquids were investigated by using the custom made sliding tester. [BMIM][I] and [BMIM][FAP] were used as lubricant. In the case of applying negative voltage, both ionic liquids showed the same friction coefficient. On the other hand, in the case of applying positive voltage, [BMIM][FAP] showed higher friction coefficient than the other. It is considered that the kind of adsorption molecule affected the friction coefficient depending on the applied electric field.

Ionic liquids, which are salts with low melting point, are expected to be used as new lubricants because of their unusual properties. Non-fluorination of ionic liquids is one of the big issues to apply them as lubricants. In this research, we used non-fluorine-based inorganic acid (e.g. phosphoric acid, and sulfuric acid), investigated their friction properties. In addition, we discussed the reaction mechanism of ionic liquids on the friction surface by using a quadrupole-mass-spectrometer and X-ray photoelectron spectroscopy.

Machinery that operates in high-temperature high-pressure water, such as cogeneration engine or heat pump, has a problem of severe wear on its sliding parts. To suppress the wear, a kind of carbon film material called DLC has been drawing attention as a solution because of its wear resistance and low friction coefficient. The focus of this research is to clarify the oxidative wear properties of various DLC films, which enables us to design the optimum DLC for high-temperature and high-pressure water environment.

Several experimental techniques are ordinarily used to evaluate the strength properties of metal nitride coatings. However, for gradient coatings, in which the chemical composition changes gradually in the normal direction of depth relative to the surface, the properties at different depth positions of the gradient layer are difficult to evaluate. In this study, our previously developed micro slurry-jet erosion (MSE) test was applied to swiftly evaluate the strength properties of AlCrSiN gradient coating. Its coating had (Al+Si) concentration continuously increasing towards the surface. The MSE tests were conducted by impacting the slurry-jet containing 1.2 μm sized alumina particles perpendicular to the coated surface, and the depth profiles of the eroded surfaces were measured and the erosion rate were obtained. From the characterization by transmission electron microscopy and selected area diffraction, the change of the erosion rate was caused by forming nano-composites and also by segregation of a hexagonal closed-packed phase (hcp).

We estimated a thickess, surface roughness and hydrogen content of transformed layer during friction test by in-situ reflectance spectroscopy in order to clarify a effect of transformed layer of hydrogenated DLC coating on low friction coefficient. As a result, we suggested that hydrogen in transformed layer maintained low friction coefficient and transformed layer controlled low friction coefficient actively.

In order to demonstrate the effectiveness of 3D structured surface texturing which is named "Material feed path" for sliding applications, a 3D textured ball joint was fabricated by SLS (Selective Laser Sintering) 3D printer. Material feed paths are fine channels applied to parts supplying some material with a sliding surface. The frictional properties of the ball joint were measured by a pendulum type friction tester. The results implied that supplying a lubricant with a sliding surface via the channels enables to keep friction low for a long term.

We proposed a novel tribo-system, which has "Material feed path" beneath the sliding surface to control tribological properties by supplying materials such as additives via the paths. The sliding specimen with "Material feed path" were manufactured by utilizing a metal 3D printer. Base oil and additives (MoDTC, ZnDTP) were supplied through "Material feed path" during sliding test. In summary, friction coefficient reduced by supplying additives to sliding surfaces via "Material feed path". It is suggested that the "Material feed path" could be one of the methods to active-control the tribological properties.

Selective laser sintering (SLS) is a rapid prototyping technique that allows us to produce complex three-dimensional parts from CAD models by sintering successive thin layers of powder with a laser beam. In this research, the following four parameters were experimentally investigated, laser power, laminate thickess, scanning speed and sweep spacing, to check the most suitable processing conditions. And our test pieces were cubic in shape with a side length of 5mm. The mechanical characteristics of the cubes were tested by compression test, and their structures were examined by SEM. The laminated thickness gives a large effect on the mechanical properties of the test pieces. There was a correlation between the laminate thickness and the void density.

Three-dimensional microstage (3D microstage) is driven by electrostatic comb actuators that provide continuous motion along three axes (X, Y, and Z) with low hysteresis, and it is used as a drive system of an atomic force microscope (AFM). In this study, we developed a cantilever-integrated three-dimensional microstage (Cl-3D microstage), in which a cantilever is mounted directly onto the SOI (silicon-on-insulator) substrate on which the 3D microstage is fabricated. The CI-3D microstage was installed in a commercial AFM, and friction distribution were measured. As the results, the relationship between scanning speed and friction force showed a similar behavior to the Stribeck curve. Moreover, friction loop measurements were performed at three different scanning speeds, and friction force was measured at effective load of 0 nN.

Carbonaceous hard coatings have great properties, such as low friction, high hardness and high wear resistance. In particular, CNx (Carbon Nitride) coating and a-C:H (Hydrogenated amorphous carbon) coating show ultra low friction coefficient (μ<0.01) in dry nitrogen gas. However, the mechanism of ultra low friction has not clarified. We should develop the in-situ measurement method of friction area during friction to clarify this ultra low friction mechanism of carbonaceous hard coating. In this research, we demonstrated in-situ measurement of surface energy on friction area during friction by manufacturing friction tester in ESEM (Environmental Scanning Electron Microscope) chamber. Moreover, we estimated the change of surface energy by friction.

Flexoelectric effect is a phenomenon of electric polarization for strain gradient in material. PZT ceramic is a well-known piezoelectric material but also shows flexoelectricity when it deforms with strain gradient. In this report, flexoelectric coefficient of PZT piezoelectric ceramic for torsional deformation is experimentally measured. In order to obtain strain gradient, torsion is applied to PZT square rod. It is clarified by FEM analysis that almost constant shear strain gradient can be obtain between counterface surfaces on partial side plane of the square rod with torsional deformation. Also when torsional deformation is given to a square rod, electric polarization by piezoelectric effect between the counterface surfaces can be negligible theoretically. Thus the flexoelectric effect can be measured by torsional deformation. Relatively large electric polarization was obtained by experiments.

This paper deals with parameter identification for a three-degrees-of-freedom (3-DOF) parallel manipulator, based on measurement redundancy. A redundant passive chain with a displacement sensor connects the moving stage to the machine frame. The passive chain is sequentially placed in three directions at approximately right angles to one another to reliably detect the motion of the stage. Linear encoders measure changes in lengths of the passive chain and the three actuated chains of the manipulator during traveling of the moving stage. The least-squares method using a Jacobian matrix corrects 27 kinematic parameters so that the length errors of the passive chain are minimized. The above calculations were performed in both numerical simulations and experiments to investigate the effect of position angles of the passive chain on the parameter identification. Moreover, measurement experiments with gauge blocks and an optical flat were performed to verify the identified parameters.

A rotational-type tripod parallel mechanism has a larger motion space and greater tilt angles. The tripod parallel mechanism for a movable stage has three legs translating on the ground. A prototype printer of the tripod parallel mechanism with rotary and linear actuators is designed and fabricated. An object is set on the movable stage of the tripod parallel mechanism a printer head is fixed over the movable stage. The motion paths of the actuators are calculated by the MATLAB-Simulink and SimMechanics block model of the parallel mechanism.

A slider-crank mechanism is important for the conversion between linear and rotational motion. When a slider-crank mechanism is making piston liner motion, the side force occurs between cylinder sides and a piston head. There are various problems caused by the side force. Therefore, the orthogonal double-slider joint mechanism has been proposed in order to remove the side force acting on the piston in our research group. Authors built an experimental equipment to consider the effect of an arrangement of prismatic pairs upon the input torque in the case of driving a water pump. The experimental device is based on a Scotch yoke mechanism, input torques are compared between the cases of a single slider shaft and a parallel slider shafts arrangement. From the experimental result, an inference is derived, that is the moment occurred by the load of the piston head acting upon the slider shaft has effects on the input torque.

This paper presents a kinematic characterization of the Origami Spring, which can change its shape from a flat, contracted state to a solid, extended state. Through observation using a real model, the Origami Spring was modelled by spherical 6R linkage with 3 degrees of freedom (DOF). To obtain a kinematic model, which enables kinematic design of the Origami Spring for real applications, mobility analysis and displacement analysis have been performed. To reveal the actual behavior of the Origami Spring: it behaves like a single DOF, displacement analysis has been formulated as an optimization problem with a single input using objective functions taking into consideration the collisions of links. Numerical examples were presented to discuss the kinematic characteristics of the Origami Spring.

In this report, a novel 3-USR parallel mechanism with large work space for haptic devices is proposed. To realize high structural transparency, these joints are composed of 2 D.O.F. spherical parallel mechanisms. The spherical parallel mechanism is composed of 2 rigid links (output link and stationary link) and three wires. Output link is connected stationary link by universal joint and is driven by three wires. In order to realize large work space, center points of three universal joints must be placed in condition that their center points are coincident. To realize this condition a novel triple universal joint is proposed. This joint is composed one ordinary revolute joint and one circular arc slider. A prototype of the triple universal joint for a desktop size haptic interface is designed and fabricated. Outside diameter of the prototype is 0.1m and its motion range is ±75°.

Although in many cases the internal thread machining the tap is used, especially since the small diameter of the things is vulnerable to twist load, easy to break during processing. Similarly, in drilling, breakage of the tool is likely to occur in cases of small-diameter tools, difficult-to-cut materials or etc., but the authors improved by adding ultrasonic vibration. This is the effect caused by applying vibration to the tool, for example, machining becomes intermittent, the cutting resistance of the apparent decreases, the tool and the work-piece lubrication and cooling is improved in the processing portion since repeated separation and contact. This study is aimed at preventing breakage of the tool according to the same effect in the screw tapping. As a result, by adding ultrasonic vibration to tapping, the resistance of the cutting is significantly reduced, and the chips become finer, but the tool is easily broken.

This study aims to develop a single-body (solid) bolt/nut model utilized in the strength design of bolted joints by using 3D-FE analysis. The model should have the same axial and flexural stiffnesses as the actual bolt/nut assembly. To achieve this, the shank diameter for free-threaded length and the shape of the slits representing mating threads in the single-body bolt/nut model are taken as parameters under axial force and bending moment loadings. The validity of the model was confirmed from the fact that axial stresses acting on the body of the single-body bolt/nut model in cylinder cover bolted joint show good agreement with those obtained experimentally from the measurements by the strain gages put on the bolt shank.

Although planetary gear sets are widely used in hybrid vehicles as a power distribution system and in electric vehicles as a high reduction system, its noise and vibration problem has emerged. There are many reports dealing with two-axis driving or displacement of planet gear under its condition, but we can see few reports dealing with three-axis driving. In the present report, three-axis driving is tested with three-axis rotation speed measuring and dynamic characteristic is investigated creating sun gear speed contour map. As a result, it's confirmed that rotation direction of the sun gear is changing under the three-axis transition. Accordingly, the input acceleration of the ring gear and carrier must be considered under three-axis driving to make the sun gear rotation direction invariable. Dynamic characteristic on a stationary rotation is affected by displacement length and speed of instantaneous center on the three-axis transition.

Planetary gear trains are presently widely used in various machines owing to their many advantages. They, however, suffer from problems of noise and vibration due to their structural complexity. Moreover, their dynamic characteristics are yet to be fully understood. Although several studies have been conducted on two-axis driving and displacement of planet gear, none has considered three-axis driving. The general driving conditions of a planetary gear train, including during three-axis driving, were investigated based on the theory of instant center, and ideal driving condition is proposed based on the experimental result which was tested on an original fully wireless test stand, in the previous study. In the present study, the centrode variation of the planet gear due to the speed fluctuations of the ring gear and carrier, and inertia of planet gear about instantaneous center were investigated as a cause of efficiency reduction.

Recently, improvement of design capability is one of important issues in industry However, it's really difficult to share knowledge of design possessed by experts with novices, because the knowledge exists depending on their skill and degree of prociency. Thus the current study aims to excavate the experts' Knowledge. We then described design objects related to action to design electronic components.

Here we report on the development of an olfactory amplifier device that collects airborne odor molecules and presents condensed odors to the user. In the proposed device, gaseous chemicals contained in the air are collected onto an adsorbent. By adding heat to this adsorbent, the chemicals accumulated on its surface are desorbed, and thus, concentrated odor vapor is generated. The user can sense trace odors as if his/her olfactory sensitivity were enhanced. However, one of the problems of our first prototype system has been its lengthy odor desorption time. It takes at least several minutes to fully heat up the granular adsorbent packed in a tube in the prototype system. Our initial investigation on the use of a thin-film adsorbent is reported here. The results show that the odor intensity amplification by a factor of six can be achieved even by a small-volume thin-film adsorbent while reducing the odor desorption time to several seconds.

Indications are, animal therapy can work effectively for the elderly with severe senile dementia, those showing little response to others due to poor communicative skills, and those with little emotion or purposeful behavior in the eye of observers. However, hospitals and nursing homes often have difficulty keeping a pet due to various problems, including allergy, infection, biting and scratching. Against this backdrop, demand is rising for a pet robot that requires no care and causes no allergy, infection, biting and scratching, and is aimed to please and comfort people and contribute to their welfare. With no pet robot so far designed exclusively for the elderly, it is becoming necessary to design a robot featuring skills to communicate with the elderly. This study conducted a questionnaire survey among the elderly, examined healing effects on them, and produced a prototype robot based on the results.

We have proposed the basic structure of a compact robot suit with two hardware-based safety devices - the “velocity-based safety device” and the “torque-based safety device”. The robot suit assists a patient's knee joint. The torque-based safety device stops the robot suit if it detects an unexpected high joint torque. Similarly, the velocity-based safety device stops the robot suit if it detects an unexpected high joint angular velocity. The safety devices work even when the computer breaks down, because they consist of only passive mechanical components without actuators, controllers, or batteries. In this paper, we describe the detailed design of the robot suit.

We have developed a humanoid hand for humanoid robot and handicapped people. This hand is called a TUAT/Karlsruhe Humanoid Hand. This hand has unique structure for a lightweight with Self-adjustment functionality by my original design, it called a Harmonic link system. I used this design for an artificial arm. It is necessary to use a glove of the natural appearance to make an artificial arm. However, I have to make the design of the hand a small size to use this glove. So I did the design to make the hand small. The sizes of fingers were small to 89%, the size of palm was small to 64.9%. It was also possible to wear the cosmetic glove made originally.

Gear skiving was developed about 100 years ago for cutting internal gears at high productivity. However, significant problems have prevented skiving from being used widespread. But recent technologies made it to receive attentions. The present paper proposes an evaluation index for continual changing work of cutting edge for internal gear skiving. From the distribution of the proposed index, it was confirmed that work for cutting became large on trailing side of cutting edge at the end of cutting.Fu rthermore, the work for cutting at topland of cutter account for large part of all. Finally, the work for cutting with cutting edges change periodically and the tooth flank of internal gear after cutting could be undulation because of the vibration of the work for cutting.

The final purpose of the present study is to create design method of taper cutter for internal gear skiving. For this purpose, first of all, the reference cutter geometry on the basis of conjugate pinion was discussed. Conjugate pinions and cutting edges must be calculated according to Variation in center distance. After that, these cutting edges are aligned along with the lead of the conjugate pinion with the minimum center of distance and a taper cutter is constructed. Comparing the conjugate pinion and the taper cutter in a same coordinate system depicted in a figure, the taper cutter was confirmed to be inside of the conjugate pinion. So, this taper cutter does not interfere with the target internal gear in its cutting process. In addition the radial clearance angles of the taper cutter were smaller than those of the conjugate pinion. And chordal tooth thicknesses at some radii of taper cutter were smaller than those of the conjugate pinion. Therefore, it was confirmed that this taper cutter had some clearances on its top land and its tooth flanks between the target internal gear and itself.

Improving quality of hobbed gears must yield high accuracy of ground gears. This can be achieved by measuring hobbed gears accurately. Pitch deviations are most crucial in grinding processes with a worm type grinder. In the preset study, a new measuring method is proposed for single pitch deviations. In this method, measured helix trace data are conditioned with Gaussian Filter to be divided into short-and long-wavelength components. Single pitch deviations are calculated from the long-wavelength components around the center of facewidth. The calculated deviations showed 62.8% lower variation in iterative measurements.

We developed an automatic damage diagnosis system of the gear tooth surface using a laser beam. Only attaching a laser sensor in a gear box, we can grasp the size and place of the damage on a gear tooth surface without using a rotary encoder. We confirmed the limit of this method against the velocity fluctuation. Furthermore, to utilize this system in the practical field, we developed a new system which was small, light weight, and low cost. The accuracy between new and conventional system was compared, and we confirmed the results were comparable level.

In recent years, high precision dual lead worm gears in JIS 4 type have been required. In this paper, the tooth contact pattern and transmission errors are set using tooth contact analysis in order to manufacture the worm gears with high precision. The dual lead worm gears in JIS 4 type were designed and manufactured based on this method and the experimental tooth contact patterns and transmission errors were compared with analyzed ones. As a result, the validity of this method was confirmed.

We measure trigger signal to estimate gear excitation force. Since the trigger signal has time delay, we can't estimate gear excitation force precisely. We consider characteristics of trigger sensors and how to measure the signals. We compared phase delay of trigger sensors and proposed a way to measure a trigger signal with less phase delay. In this paper, we used electromagnetic pickup, photointerrupter and hole device as a trigger sensor. We estimated phase delay of these sensors comparing with gear vibration. Photointerrupter and hole device had less phase delay than electromagnetic pickup. Photointerrupter and hole device had most of the same phase delay. But phototointerrupter had slightly small phase delay.

Planetary gear system has the strong point at their compact size comparing with high load capability. But it is more complicated comparing with parallel shaft gear systems. In this study, we made a planetary gear apparatus that planetary pinion's vibration can be measured. And the effect of misalignment error on sidebands components around mesh frequency vibration component experimentally.

In order to investigate the influence of different shot peenings on the rolling contact fatigue life of case−hardened steel, the thrust type rolling contact fatigue test was performed with a ball−on−disk contact tester. In this study, the case−hardened steel disks were treated by the shot peening with a shot diameter of less than 0.1 mm. The surface hardness and the surface compressive residual stress of all the test disks were increased by the shot peening, and the surface roughness of most test disks was decreased by the shot peening. As the result of the rolling contact fatigue test, the rolling contact fatigue life of all the test disks was improved by the shot peening. The rolling contact fatigue life of the test disks became longer as their surface roughness became smaller. Therefore, it follows from this that the shot peening with a shot diameter of less than 0.1 mm, which can provide the decrease in surface roughness as well as the increase in both surface hardness and surface compressive residual stress, is suitable for the improvement in the rolling contact fatigue life of case−hardened steel.