An insert-type formed gear cutter with positive both side and rake angles for cutting large module gears was designed and manufactured. The shape of insert and design parameters of the cutter were interactively decided in consideration of interference and a relief angle at a flank face using the software developed in this paper. Cutting tests with trial-made gear cutter were carried out. As the results, sufficient accuracy as a cutter for roughing large module gears was obtained.

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In the previous study, we have developed involute-cycloid composite tooth profile gear. Involute-cycloid composite tooth profile gear has some advantages against typical involute gear in tooth bending strength, surface durability, and power transmission efficiency. However, it is expected that involute-cycloid composite tooth profile gear is sensitive to center distance error since this tooth profile includes cycloid part. In this study, we calculated the tooth root stress and tooth contact stress of involute-cycloid composite tooth profile spur gears with changing center distance and some design parameters which define the tooth profile. Then we have searched design parameters which reduce the influence of center distance error.

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The purpose is developing the simulation of efficiency of helical gears based on the frictional loss generated by the meshing. The frictional loss was calculated by applying the visco-elastic-plastic model. The calculation of the efficiency was carried out in case of using ATF and traction oil. The calculation of the traction curve agreed with experimental result. The tendency of calculation that efficiency became higher if rotational speed increases agreed with experimental result. And the calculated efficiency agreed with experimental result in the case of automatic transmission fluid.

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Windage loss is one of the losses involved in the power transmission system with gear pair. The windage loss could be reduced when atmospheric pressure around the gears might be dropped. In this study, a gearbox is constructed, which has only outlet port of the air in the gearbox, no inlets. Atmospheric pressure around the gears in the gearbox could be dropped by pumping effect at the meshing of the operated gear pair itself for power transmission. Phenomena of the pressure drop in the gearbox are observed experimentally. In this report, the experimental results are shown, acquired with variations of experimental conditions such as gear types, clearances between the gears and the walls inside of the gearbox.

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Power distribution by the plastic gear is decreased for the lighten machine and the compact machine. Also, the reduction of a few energy losses, too, is wanted for the global environmental problem. Gears with a different profile from the involute curve could be effective for the reduction of energy loss in gearing systems, and could enable them to be small and light. The present paper describes plastic gears with a sine curve profile, and analytically discusses their possibility of reducing the energy loss. As a result, it is confirmed that gears with a sine curve profile have smaller sliding between tooth flanks than ones with the involute curve, and would enable the energy loss to be reduced.

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This study has proposed a method of friction reduction and lubricity improvement for meshed gears, which is based on ultrasonic oscillation. This report describes gear and shaft design using the finite element analysis (FEA), and results of experiment using an ultrasonic actuator. First, FEA calculated axial and radial amplitudes of vibration. A modified gear profile improved the axial amplitude by 50% as keeping the radial amplitude low. Next, a shaft with the gear was oscillated by an ultrasonic transducer excited by two types of driving amplifiers. Measurements with laser Doppler vibrometer demonstrated that the axial and radial amplitudes of vibration were 1.3μm (p-p) and 0.49μm (p-p), respectively.

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Transmission efficiencies of high reduction face gear drives were investigated. The obtained results are as follows. (1) The equation to calculate theoretical efficiencies of general face gear drives was derived and the calculation examples were shown. (2) In face gear drives, there is an optimum offset between pinion and gear axes to maximize the efficiency. (3) The face gear drives with gear ratios were made and the efficiencies were measured. As the results, the high efficiencies of 88〜95 % were obtained. In this case, the estimated friction coefficients were in the range of 0.05〜0.07.

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A cerebral aneurysm is the dilation, bulging, or ballooning out of part of the wall of a vein or artery in the brain. If the cerebral aneurysm ruptures, it will become serious life-threatening condition. An aneurysm clip (sugita clip) is a medical instrumentation that is used in operation of the cerebral aneurysm to clip the ruptured aneurysm and to reduce the risk of rebleeding. In order to prevent the sugita clips from slipping out of the blood vessels, a number of pyramidal dimples are formed on their clamp surfaces. However, it was not verified whether the form of pyramidal dimple was optimum or not. In this research, we used a THG laser process machine to produce the clamp surface with dimples or grooves. Frictional characteristics of each surface texturing was examined.

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The patterning surface which formed the dimple at regular intervals was made by laser beam machining. Influence of interval and depth of dimples of the pattering surface on friction behavior at low sliding velocity was investigated by using the reciprocating friction tester in lubricated condition. As a result, it was found that the pattering surface consisted from shallow dimples and the dimple interval of 29 μm was the most effective for low friction behavior.

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In this paper, the effect of the texture dimensions on sliding characteristic of the parallel plate was described. According to the dimensions of the texture, the friction coefficient was measured using three kinds of dimples which were varied only the depth. The result showed that friction reduction effect in the mixed lubrication regime was bigger, as the dimple is shallower. In the other regime, we could not find the difference on friction depend on the depth. And, friction coefficient was measured using the two kind of test piece in order to examine the effect of specimen size on the friction reduction effect by the texture. As the result, the fluid lubrication regime tended to narrow with that the specimen size was small. In the dimple pattern, it was effective in the mixed lubrication regime, when the contact area was small.

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The present study describes an applicability of lower-flow-rate shot peening treatment as machining process to smooth curved tooth surfaces. The dependence of impact media on the dimple geometry was evaluated using a mirror finished flat surface in advance to the treatment of the tooth surface. It was found that dimple geometry mainly depended on the media size and that the surface groove of the tooth surface disappeared using the zirconia beads. Furthermore, an increase in the bending fatigue strength of the gear teeth at larger cyclic number was confirmed.

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The present study describes the effect of heat treatment of functional graded material fabricated by fine particle peening treatment that is one of the surface modifications. Fine tungsten carbide particles accompanied with steel beads were penetrated on the target alloy steel surface by peening. Heat treatment was applied after the peening to melt and infiltrate of the penetrated tungsten carbide into the alloy steel. Results of indentation measurements showed that an applicable heat treatment was effective to improve the hardness. A thrust type rolling contact experiment was also applied to the modified surface, superior anti wear properties were found in the heat treated specimen.

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The carbon nitride (CNx) coating is one of the promising materials such as high wear proof, superlow friction. It was reported that CNx coating showed superlow friction when it slid against Si_3N_4 ball in N_2 environment. From the view point of industrial field, 1.0 μm thickness and 20 GPa hardness is necessary to CNx coating. We investigated the effect of substrate cooling temperature, N ion beam accelerate voltage, deposition rate, and the thickness on its hardness. As a result, N ion beam accelerate voltage, deposition rate, and thickness was not effective to the hardness of CNx coating. On the other hand, it was clear that the CNx coating hardness increased from 10 to 20 GPa with decreasing of substrate temperature. From the Raman analysis, I_D/I_G ratio and G peak position decreased with decreasing substrate temperature. These results indicated that sp^3 structure which included in CNx coating increased, and then the hardness of itself increased.

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Effects of temperature and stress on the structure change of the diamond-Like carbon (DLC) film were investigated by using the micro laser Raman spectroscopy. The DLC films were deposited on the stainless steel substrate by the plasma based ion implantation and deposition (PBII&D) using CH_4 as a raw material gas. Annealing tests were accomplished under the stress field by pressing the glass ball indenter on the DLC film. As a result, the changes of structure were observed in the annealed DLC films at temperatures over 648K. It is considered that the desorption behavior of hydrogen influenced the difference of structure changes between the loaded and the unloaded area of the DLC film.

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Recently, coating surfaces with hard thin films has been used to prevent strength reduction of the surfaces. This method is effective in reducing the friction and the wear of sliding surfaces in machine structures. The measurement of the thin film is very difficult. However, their characteristics are very important in engineering. In this study, we pay attention to Multi-layer Thin Films used for electronic devices. In order to validate the characteristics of Multi-layer Thin Films, we coated Multi-layer Thin Films such as Titanium (Ti) and Copper (Cu) on glass wafer, and measured Nanohardness characteristics of it by Nanoindentaion.

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Recent developments in nanotechnology, such as the production of micro- and nano-electro-mechanical systems (MEMS and NEMS), have enabled the miniaturization of structures. However, it is also necessary to establish techniques for evaluating the mechanical properties of micro- and nanostructured materials. A nanoindenter is a tool for directly measuring the depth profile of the mechanical properties of thin-film materials. In this article, we will explain the principle of nanoindentation and the difficulty involved in the determination of contact area. Then, we will discuss the technical advantages of nanoindentation using our experimental data.

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Degradation of lubricating oil is roughly classified into two types, one is caused by solid particles and the other is caused by oil oxidation products. Diagnosis methods for solid particles in lubricating oils have many standards and research. However, there are few diagnosis methods for the oil oxidation products. In the present work, I developed new method to evaluate a little difference of the contamination level of lubricating oils, especially for oxidation products. The relation between reflectance of the membrane patch made transparent using degradation oils, which were used in actual machines, were investigated with a spectrophotometer. As a result, I could distinguish and evaluate a little difference of the contamination level of lubricating oils by measuring the reflectance of the membrane patch in the face side and the back side.

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The effect of surface roughness on surface rigidity was investigated using four different model surfaces of S45C steel and also machined surfaces of die materials of S45C, SKD11 and cemented WC. The specimen was pressed with a polished cemented WC specimen by an oil hydraulic press machine. The rigidity was estimated from the gradient E of stress-displacement curve. The parameter E/E_0 was linearly proportional to the surface parameter Vmc/Vmp, where E_0 is the gradient of the bulk, Vmc the material volume in core zone fraction and Vmp the material volume in peak zone volume from Abbott's bearing curve.

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To clarify the sealing characteristics of metal gasket seals, the observation of the real contact area on seal surfaces is very important. In a previous work, to determine the leakage flow paths between the gasket and the flanges, the real contact situation between them was observed using a thin polymer film 1 μm in thickness. In this research, we use a laser microscope with wide field of view recently developed in our laboratory. The static seal consisted of a ring-shaped copper gasket and the two steel flanges that held the gasket in place. Gasket width was 5 mm in the radial direction. The gasket surfaces were finished by polishing with emery paper. The contact surfaces of the flanges were finished by lath turning. After unloading, the whole seal surface of the copper gasket indented by the ridges of the flange was directly observed with the laser microscope. The observation indicated that the leakage flow paths on the gasket surface were the radial direction perpendicular to the lathe-turned groove and the circumferential direction along the groove.

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In a paper feeding system, a contact condition analysis between a rubber roller and a printing paper is needed for a stable feeding operation. Direct observation of the apparent contact area between the rubber roller and the thermal print head is also necessary for better understanding of the contact condition. However a contact microscope technique takes a lot of time to measure the real contact area. Thus another new technique is expected for faster observation of real contact area. In this paper, it was confirmed that a newly developed laser microscope with wide field of view was able to observe real contact area between the rubber plate and the glass plate. Then a distribution of real contact area of the rubber roller against the glass plate was also observed by this technique. In addition the micro-slips of the rubber roller were measured when the some torque was applied.

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Along with the steadily rising elderly population in Japan, the number of aged persons with difficulties in walking is increasing. We have proposed a walking support machine for assisting the gait exercises of the patients in hospitals. The walking support machine has devices to unload patient's body weight and to prevent patient's falling. These devices consist of only mechanical components without actuators, controllers and batteries. A brake mechanism is used in the device to prevent patient's falling. In this paper, first, we analyze the brake mechanism. Second, on the basis of the analysis results, we design and develop the device to prevent patient's falling. The usefulness of the device to prevent patient's falling is experimentally examined.

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A walking assistance device using a flexible shaft was developed. A combination of the flexible shaft with a worm gear was successfully adopted on this device to modify its appearance simple and suitable size. This device is also controlled with a hybrid-control system both torque, ankle joint range, and knee joint. In this system, the tensional spring constant of the flexible shaft is taken into account to the control power and the rotating motor of joint angle. To expand the area of where an equipped parson can walk with the device, a self-contained system that operated with SH-4 microcomputer and actuators, which consisted of motors and gears, were put in the small backpack, and Lithium-ion battery was utilized. Therefore, the equipped parson and patient can freely walk both in and out of doors environment.

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The devices have been developed for elderly or rehabilitants to assist walk in a form of wearing type with electric devices. But these wearable walkers are expensive for users because this walker includes plural actuators and control computers. And more, there is a problem that the weight of the walker increases. Therefore, we suggest a walker which enables low cost and light weight. Concretely, we push forward development of the wearable walker which does not need electric devices and can be controlled by one input. In this paper, we suggest the walker which is designed planar six-bar linkage and prove utility of the walker.

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A new apparatus to assist an elderly person to stand up, as well as leaning forward the upper body, has been developed. The mechanism of the apparatus enables to shift the person's center of gravity along an adequate trajectory during standing up process, so as not to cause strain for each joint of the elderly's leg. The apparatus also assists a person to alter from standing or sitting posture to lying posture. Although the mechanism has multiple links and joints, only one actuator is required to transform the apparatus between aforementioned three postures. The length of each link of the mechanism has been determined from their effect on the backrest angle when each link length is changed. Each torque of hip and knee joint of the person while standing up was calculated, and effectiveness of the apparatus has been confirmed.

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The present study discusses the beauty of biped walking activity analyzing data points which are displacement, velocity, and acceleration of the waist, knee and ankle to time of a fashion model on a cat walk and the average adult man and woman's walking. Also, the differences in ankle displacement between a fashion model on a cat-walk, which is a beautiful biped walking activity, and the average adult man and woman's walking activity are discussed.

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This paper describes a flexibility control of an output link of redundant closed-loop mechanisms with elastic elements. The desired non-linear stiffness is specified with several pairs of external force and elastic displacement of an output link. By setting virtual torques at passive joints, a system of closed-loop equations and force balance equations can be solved. The actuator inputs can be obtained so that virtual torques become zero. The validity of the proposed method is verified by simulations and experiments with a prototype with 9 DOF and 6 actuators.

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Draw bending is a method of bending a straight pipe into complex 3-dimensional shaped pipe. This method needs a gripper, which grasps complex 3-dimensional shaped pipe with large gripping force and small contact pressure. The purpose of this research is to develop this gripper. In the present paper, the gripper which can grasp a 2-dimensional shaped pipe with large curvature is proposed. The gripper is composed of multiple gripping units. Relationship between kinematic parameters of the gripper and the minimum radius of curvature is geometrically analyzed. Relationship between the parameters and the maximum pulling force is theoretically and experimentally investigated. The result shows that the proposed gripper can grasp a 2-dimensional shaped pipe which has large curvature.

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This paper presents the peg-in-hole task by a position-orientation decoupled parallel manipulator. This manipulator can achieve fast and accurate positioning and fine orientation adjustment of the platform. In order to enable the peg-in-hole task by this manipulator without force sensor on the platform for reduction of cost and moving mass, impedance control system with estimation of external force on the platform by measuring motor torque has been constructed. Controller design taking into account the allowable limit of position error and contact force has been presented. Experimental result of peg-in-hole task illustrates that the proposed impedance control system was properly designed.

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According to development demand of 6 axis precision stage corresponding to vacuum chamber, a parallel mechanism stage has been developed. This parallel mechanism stage has vacuum adaptability as low degasification and low generation of heat. Moreover, Double Ball Joint was used for precise positioning. This paper reports on the design of parallel mechanism stage corresponding to the use in the vacuum chamber.

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Human safety is one of the most important issues in human-friendly robotics. We have proposed the safety device to improve the safety for humans in the robot's workspace. The safety device consists of only mechanical components without actuators, controllers and batteries. The safety device locks the robot's joint after detecting the overdrive on the basis of the joinfs angular velocity. In this paper, first, the concept of the safety device and the mechanism are explained briefly. Second, the mechanism of the safety device is theoretically analyzed. Third, the safety device is designed and developed on the basis of the analysis results. Finally, the usefulness of the safety device is experimentally examined.

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The present study aimed to develop a 5DOF micromanipulator that consists of the injection molding pantograph mechanism which has the function that the output hand can change the holding direction around one fixed holding point. In this thesis, the method of deciding the pantograph mechanism's link shape and dimension avoid interferences when each link moves is discussed.

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For tightening bolted joints, the calibrated wrench method is widely used in practice. In this method the axial tension of a bolt is controlled by measuring the wrench torque. Also widely know the high initial axial tension assure the tightening reliability. However the method is not so accurate since the measurement of axial tension is indirect. In this paper, the statistical distribution of the magnitude of the combined stress(the von Mises Equivarent Stress) by shear strain energy criterion in bolts, which are tightened by the calibrated wrench method was formulated. And also we discussed the safety factor for capability stress limit and/or fatigue limit vs. additional stress by working load. As an example, the distribution of combined stress was shown for a metric screw. Finally this research established the analysis and calculating routine for the optimum tightening torque on bolted joints using the ellipse of confidence limit.

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Many papers have been published on the self loosening of bolted joints, making estimations of the locking effect from laboratory tests using a loosening test machine. However this kind of test method is only effective for the comparison of locking devices. In this paper we propose a method for estimating the absolute lock effect during actual machine operation ,that is construction machinery and material handling equipment. The authors found that there is a linear relation between axial tension and the time after the tightening on a log-log scale, in both static and dynamic loosening. Based on this relation, the authors propose a method for estimating the decrease of axial tension accurately after long hours of tightening by measuring the initial behavior as the bolt loosening evaluation chart.

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Although a large number of studies have been made on screw threads, little is known about mechanical screw. The aim of this paper is to improve the reliability of bolted screw joint design by clarifying the relationship between hardness and tensile strength and strength use efficiency of cross recessed pan head mechanical screw. In conclusion, (1) Real tensile strength of mechanical screw products is lower than the value estimated by relational expression, (2) Tightening axial force has a constant limiting value, (3) Strength use efficiency decreases as the nominal diameter becomes bigger.

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A hypothesis was presented concerning the effect of the axial residual stress at the thread root of a bolt induced by thread rolling on its fatigue strength. However, this has not yet been verified since the residual stress which may exist locally around the thread root can neither be measured nor estimated with sufficient accuracy. This study aims to seek the possibility of the application of X-ray diffraction method to the residual stress measurement on the bolt thread root. The measurement has been done for the groove-rolled specimen made of M10×1.25 bolt brank with larger thread pitch and root radius. The results show that the local residual stress should be measured on very small area (the width of which is less than 5 % of the radius), and that only 5 % misalignment in axial direction is allowed for the measurement within 10 % accuracy. Finally, it is concluded that X-ray measurement for M10×1.25 bolts is unrealistic since the collimator of 30 μm diameter with the positioning accuracy of ± 10 μm is necessary.

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This paper describes a study on the load bearing capacity of high density sintered metal gears with surface-densification. High density sintered metal gears were hobbed, and then surface-rolled. These gears were case-carburized after surface-rolling. The effect of surface-rolling on the surface property was examined by measuring porosities and hardness near surfaces of rolled gears. Running tests for these gears were performed, for the cases when these gears were used as a driver or follower. A failure mode and load bearing capacity of high density sintered metal gears and the effects of surface-rolling on the load bearing capacity of sintered metal gears were determined, and the results were compared with those of carburized wrought steel gears. The experimental results show that the load bearing capacity of high density sintered metal gear with surface-densification is comparable to that of a carburized wrought steel gear.

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The rolling contact fatigue test was conducted with thermal refined SCM and SNCM rollers with a hardness around HV350. The failure mode of all rollers was pitting caused by surface cracking. The surface hardness of rollers after test was increased by work hardening. The rolling contact fatigue strength increased with increasing surface hardness after test. The plastic deformation at the contact edge was discussed with the misaligned roller test. The strength of misaligned roller was the lower. The portion where the pitting failure occurred was not at the contact edge but toward the center of contact width. The plastic deformation at the contact edge could occurred at rather early stage of the test.

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This paper presents a study on effects of rim and web thicknesses on root stresses of thin-rimmed helical gears. Root stresses of thin-rimmed helical gears with symmetric web arrangement of various rim and web thicknesses, which were meshed with the solid helical gear, were measured from the beginning of engagement to the end of the engagement by the strain gauge method. The changes of the root stress from the beginning of engagement to the end of engagement were examined for the thin-rimmed helical gear with symmetric web arrangement. The meshing position (worst loading position), where the maximum root stress occurred, was determined for the thin-rimmed helical gear with symmetric web arrangement. Effect of rim and web thicknesses on the root stress, the maximum root stress and the position of the maximum root stress were clarified.

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V-ribbed belts is a friction transmission belt, and is used as alternator, compressor and water pump drives using the power of crankshaft. The V-ribbed belt consists of a fabric, cords, adhesive rubber and rib rubber. Recently, according to the crash safety technology for the engine room, belt width is required to be reduced. Associating with the narrow width, the cord tension increases and then a new failure mode of "pop-out" is initiated at the belt side face. In this study, the failure initiation mechanism of the pop-out was discussed caring out some observations and FEA. The first step of the pop-out was the failure of the strand at the cord side-surface.

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