We investigated difference of lubricity of triolein, tristearin and rapeseed oil as a reference under high temperature conditions for acceleration of oxidation degradation. Though the triolein consisting of the monounsaturated fatty acid showed superior oxidation durability and oiliness to the rapeseed oil including the polyunsaturated fatty acid, phenomena which might be caused by corrosion and elimination of adsorbed film were observed on both lubricants. On the other hand, there was a possibility that the tristearin consisting of the saturated fatty acid has a superior forming capability of adsorbed film and not be related to corrosion.

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In recent years, the wind power generation equipment is attracting much interest in the world. The equipment used on the ocean is affected adversely by seawater . Generally it is said that rubber is weakened by water or seawater. So, it is expected that the oil seals used for these machines are affected by seawater. In this study, rubber materials for oil seals used under seawater environment were investigated to clarify the effect of seawater on the friction and wear characteristics. Three kinds of rubber samples (fluorocarbon rubber, silicon rubber, nitrile- butadiene rubber) immersed in seawater used in this study. Tensile test and frictional test were conducted. As a result, tensile strength of any rubber samples before and after being immersed were almost constant irrespective of immersion in seawater. On the other hand, the friction and wear characteristics of silicone rubber and fluorocarbon rubber showed a slight change after being immersed for two month. And, the friction and wear characteristics of nitrile- butadiene rubber was almost unchanged.

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In this study relationship between variation in roughness on the surface and friction coefficient after running-in process was investigated. A component of mechanical face seal between a rotational SiC ring and a stationary carbon ring were used as the specimens in the tests. Six tests were conducted under the same running-in process using the same new specimens. The profiles of friction coefficient in the Stribeck curve diagram could be distinguished among three groups. One group has high friction coefficients, another group has low friction coefficient and the other has the medium values. The comparison between the measured roughness after the running-in process and the three groups of the friction coefficients showed that there existed the correlation between the behavior of friction coefficient and variation in roughness on the stationary surface in the hydrodynamic lubrication condition. In the case where the friction coefficient was high the roughness increased slightly and uniformly over the contact area. In the case where the friction coefficient was low the roughness increased more and non-uniformly.

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Ethanol is recently focused as a new liquid rocket fuel because of its environmental friendliness and easiness to be stored for a long time, though liquid hydrogen and kerosene are commonly used now as liquid fuel for rocket engine. The development of a turbopump for the rocket engine that pressures ethanol to the reaction chamber as liquid fuel is urgently required, but it has not been completed. Particularly, though a performance evaluation of machine components such as shaft seal, bearing and so on is definitely important, there is not enough research on the machine components for operation under ethanol lubrication. We focused the characteristics of lip seals for the turbopump in rocket engine in the study, and designed and developed an experimental apparatus for their performance evaluation under high-pressure and ethanol-lubricated condition. Two kinds of lip seals that made from acrylic rubber and fluorine-containing rubber were prepared. Rotational speed was set constant as 1,000 rpm, and seal pressure was changed from 0.15 to 0.7 MPa for the test. Experimental results showed that friction torque of the lip seals increased with increase in seal pressure because of the increase in the contact pressure between the seal and shaft. Leakage of ethanol from the seal increased until 0.3 MPa as seal pressure, but was almost constant even over 0.3 MPa. We finally concluded that lip seal has a possibility to be applied for the turbopump for ethanol fuel.

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To clarify the mechanism of tapered seals located at the end of fluid dynamic bearings used in spindle motors for hard disk drives, the behavior of the fluid surfaces of the seals when the spindle motors are subjected to shocks is analyzed and solved. As a continuation of the last paper this paper discusses the influence of motor orientations and surface tension contact angles on the behavior of fluid seal surfaces. The relationship between oil leakage and motor orientations is affected by the responses of the rotor in the motor. When the responses of rotors are assumed to be the same in the vertical orientation and in the horizontal orientation, oil leakage more likely appears in the horizontal orientation. Contact angles tend to be larger when the fluid surface is moving. Accordingly the seal design should take into account of the moving speed of the fluid surface. To prevent oil leakage from the seal, it is effective to reduce the vibration amplitude and the moving speed of the fluid seal surface by providing an adequate clearance and length of the seal and higher stiffness and stronger damping of bearings.

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The low fuel consumption, long life, and low noise are required in the automobile tire. In order to evaluate these performances, it is necessary to understand the friction and wear properties of tire tread rubber. The experiments in laboratories often show differences to the results in real driving. It seems that the inconsistency is led by the differences of severities between the laboratory test and real driving. The purpose of the study is to evaluate the wear properties of rolling sliding friction of the rubber at low slip ratio. Experiment is carried out using a rolling drum into contact with a rolling rubber specimen. Abrasive papers were placed on the drum surface in order to assume the surface roughness of the actual road. It is clearly seen that the tangential force coefficient and linear rate of wear depends heavily on the slip ratio and surface roughness. The protrusion wear marks formed on the rubber surface moved faster as the slip ratio increased.

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Friction and wear phenomena have many unsolved phenomena, and there are many problems which are not yet established theoretically. Since especially brake material is a composite material, its modification and destructive mechanism are very complicated. Then, using a frictional surface microscope, in-situ observation of the friction interface was carried out to observe, evaluate and clarify the mechanism of friction and wear. By this research, a speed of the development of friction materials will be improved, and the development of a new brake material will be preceded.

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A Paper-based friction material has been used in the wet clutch with automatic transmission fluid (ATF) in order to obtain good friction characteristics, however friction behavior of wet clutch is not sufficiently clarify. In this study, paper-based friction materials were rubbed with ATF using a pin-on-disk type tribometer and the contact area between the prism and the paper-based friction materials was observed using the total reflection optical system. Two kinds of paper-based friction materials, poly-para-phenylen terephthalamide (PPTA) fiber-filled friction materials and PPTA + carbon fiber-filled friction materials were used. As a result, it was found that coefficient of friction tend to increase and real contact area tend to be constant as the sliding speed increased. In addition, both coefficient of friction and real contact area tend to increase as the increasing the contact pressure.

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It is very important for the machine under operation to know oil film thickness. If fluorescent agent is dissolved in oil, oil film thickness is measurable by fluorescence intensity. 2, 5-Bis (5-tert-butyl-2-benzoxazoyl) thiophene was selected as fluorescent agent, and it dissolved in PAO (Polyalphaolefin). To know fluorescent property of fluorescent agent, fluorescent spectrometric analyzer was used. The 475nm light of ultraviolet was used as a light source. Oil film thickness was measured by getting to know the intensity of fluorescence exited by ultraviolet light. It is thought that fluorescence intensity is subjected to influence the substance of ground on which the oil containing a fluorescent agent is placed. The examinations which investigate the relation between fluorescence intensity and oil film thickness were done also on engineering plastic with until now few example of measurement. As a result, it turned out that it is affected in the fluorescence characteristic and color of the substance of ground which places the oil containing a fluorescent agent.

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Lubricating oils are used in various machines and devices. However, lubricating oils are degraded in operation subject to usage environment. Degradation causes of lubricating oils are roughly classified into two types, one is caused by solid particles and other is caused by oil oxidation products. Diagnosis methods for solid particles in lubricating oils have many standards and researches. However, there are few diagnosis methods for oil oxidation products. Furthermore, oxidation degradation of the turbine basis oil becomes a serious problem in power generation plants recently. Therefore, on-site degradation diagnosis method which can detect oxidation degradation of lubricating oils at the early stage is desired for the proactive maintenance. We have developed degradation diagnosis method of the lubricating oils which paid the attention to coloration of the membrane patch with contamination. We prepared sample oils which were degraded by oxidation in the laboratory. We measured the color of membrane patches produced from sample oils using the colorimetric patch analyzer. As a result, it was verified that this method could detect oxidation degradation of the lubricating oils at the early stage.

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In a previous work, we developed a new type laser microscope that has features of confocal scanning type and wide field of view. This new type of laser microscope was applied to detection of micro/nano-fine flaws over a wide area of 8 x 10mm on metal or glass surfaces. Several micro fine flaws were produced on stainless steel by scratching the surfaces with a diamond stylus. The fine flaws on the metal surfaces were able to be seen through the laser microscope we developed. Furthermore, submicrometer-flaws were produced on Si substrate or cylindrical-glass surface by focused ion beam technique, FIB. The surfaces containing those micro/nano flaws were observed with the laser microscope and the flaws on the Si substrate could be seen. It can be said that the flaws on the glass surface is slightly difficult to observe than those on the metal surfaces due to the wavelength of the laser we used.

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Boundary lubrication is one of the most interesting topics in the field of tribology. Under the boundary lubrication, oiliness additives mixed in a base oil are expected to form adsorption layers on a sliding surface and then achieve low friction and high wear durability. Many classical reports confirmed that the adsorptive performance of an additive to the surface greatly affects the friction coefficient of surface. However, quantitative analysis for the physical and chemical properties of adsorption layers had not been done until recent years because the adsorption layers are very thin, less than several nanometers. To clarify the phenomena under boundary lubrication, thickness and density of an adsorption layer of oiliness additives formed on a metal surface under the lubricating oil were directly measured by neutron reflectometry that is one of in-situ analytical methods. A copper surface on ultra-flat silicon block was formed by physical deposition. The poly-alpha-olefin was used as base oil, and some kinds of deuterated acids were used as additives. The reflectivity profiles for such sample were acquired by neutron reflectometer in air, in PAO and in PAO mixed with additive. Fitting operation based on Parratt's theory showed that the thickness of the additive adsorption layer on the metal surface was very thin, approximately 2.3-2.4 nm and its density was 42-100% of bulk acid. Neutron reflectometry is a quite useful tool for in-situ analysis for the interface between the metal surface and lubricant.

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This paper describes tribology in micro-scale order that is influenced by low friction force caused by low normal load. Recently, micromachines have been used in various fields. Tribolobical property in micro-scale such as micromachines move is known to be different as compared to macro-scale tribology. The aim of this research is to clarify microtribology and evaluate it. We selected diamond stylus tip and glass wafer as specimens in this research. In this experiment, friction force between two specimens is measured by using scratch tester. Besides, we observed friction groove and measured its depth with SEM. In conclusion, some knowledge about microtribology has clarified.

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Wear equation for the prediction of wear amount has not yet been established since many complex problems exist in wear phenomena. Adhesive wear is one of main wear mechanisms, and leads to the failure and destruction in machinery such as seizure. That is why, it is very important to predict the wear amount in adhesive wear in designing and developing a sliding material. In the elementary process of adhesive wear, the generation of wear elements in real contact area is the inception of the wear process. The examination in atomic scale is needed because wear elements is generated in nano-scale. However, the experimental investigation of such an atomic level needs a special experimental environment. In this study, the elementary process of adhesive wear was simulated by using a molecular dynamics method. The simulation was performed with several paired metals. As a result, it was found that there is a good correlation between the simulated results and the actual experimental results.

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Frictional force microscope (FFM) and atomic force microscope (AFM) is a powerful tool for micro-tribology, although the signal-to-noise (S/N) ratio is not well investigated. In this paper the S/N ratio of force signals detected by the optical lever deflection method used in the FFM and AFM is investigated, and as a result the S/N ratio the in inversely proportional to the radius of the optical spot at the divided photodiode. This means that the smaller radius of optical spot at the photodiode generates the higher signal-to-noise ratio in force signals. Possible methods to realize the smaller radius of optical spot by employing the optical methods are introduced. One of them are demonstrated experimentally, which shows high S/N ratio.

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Thin and flexible continuous mediums such as plastic films and thin metal films are called web. These are used for Liquid Crystal Display (LCD) and lithium secondary batteries in high-functioning products. These films are produced by roll-to-roll process. This process is able to add extrinsic value continuously and apply to mass produce to the web. However, web defects easily occur because the web becomes thinner for low costs. It is a matter of common knowledge that a concaved roller has the effect for preventing wrinkle. The concaved roller has minimum diameter at the center of width and maximum diameter at the edges. The force across the width direction generated by made of the diameter difference. Owing to the effects of the wrinkle prevention, the concaved roller has been used in many machines, such as to produce LCD touch screens, solar cells etc. However, as far as we know, there has been little experimental study about the wrinkle prevention effects by concaved roller. Therefore, we carried out an experiment for wrinkle prevention effects using in the concaved roller and discussed the effect of the shape of the concaved roller.

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These days the high friction and low wear brake pad is needed from the viewpoint of environmental problems. Containing much kind of materials such as resin, abrasive, fiber, solid lubricant and so on, the brake pad is so complicated that we cannot design it theoretically. So, we simulated the brake pad model using only resin and abrasive, and suggested the way to design the high friction and low wear brake pad theoretically. Concretely speaking, we investigated the relationship between the properties of abrasive in the brake pad model and the ratio of friction coefficient /u and specific wear rate K (K/u) using the abrasive theory. The properties of abrasive are the shape (ball, circular cone, pyramid) , size, density, apex cone angle (of the circular cone and pyramid) , open angle, normal load and ellipticity (anisotropic abrasive or isotropic abrasive) . Then we found that the anisotropic abrasive (sliding direction: sharp direction) is the best shape and the most densely packed condition is the best condition.

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It is an energy-saving part letting the lubricant reduces friction and the abrasion of the contact surface for a machine, and a machine become high efficiency. However, environmental pollution by the outbreak of carbon dioxide at the time of the destruction by fire disposal or the toxic substance and influence on human body are concerned a lot about with a lubricant of mineral oil. Therefore I paid attention to the vegetable oil as the substitute of mineral oil. From a past study, as for the sesame oil, deterioration was slower than mineral oil among several kinds of vegetable oil. I paid attention to this sign and am intended to inspect possibility of the vegetable oil and perform a breakdown test of the new grease which assumed sesame oil basis oil. Therefore I design the breakdown test device from the beginning using 3DCAD and I examine it in a more severe state and evaluate grease. I could confirm maintenance of the grease performance for a long time, and, in a normal temperature examination, it followed that I could find utility. However, solidification of the grease by the oxidative degradation happened by the high temperature examination, and a weak characteristic was seen in heat. Therefore I inspect an antioxidant with the ability for adaptation in sesame oil now and finally aim at the development of the environmental harmony type grease with the utility.

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When the body fastened by the bolt is given thermal load, for example part of the bolted screw joint of an internal-combustion engine, the flanged connection of the piping structure of a chemical plant etc, bolt axial tension (initial clamp capacity is included) is change with the additional axial tension occur by thermal load, or with the reduction axial tension by heat is removed. It is unknown what kind of influence an action of a washer has on bolt axial tension to that phenomenon. The influence is considered by concluding two blocks of an aluminium alloy with a bolt, a nut, and the washer (rigidity with material or a form size differs) of various conditions, and giving heat load in a heat source. About the thickness of a washer, each shows the same axial tension action, and about the size of a washer, the one where a washer is larger is hard to generate both additional axial tension and an axial tension fall. About the axial tension action by the difference in the material of a washer, it turned out that it is dependent on Young's modulus.

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We developed a new diagnostic method by using laser beam. A tooth surface is irradiated by zonal laser beam from an oblique direction, and then the irradiated laser beam line is shifted along the height of the tooth according to gear rotation. The variation of the voltage proportional to laser reflection between initial and present conditions are compared, and it can be grasped condition on the tooth surface such as initial or abnormal abrasion, pitting, etc. We furthermore developed a method of automatic and remote damage diagnosis on a gear tooth surface according to various gear spec by using the angle-distance relation map which made from pre-measured data of a same material and heat-treating, and taking into account the influence of adjacent teeth. The measured data was agreed well with the predicted data made with this method, therefore we can diagnosis the condition of various products automatically.

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This paper describes optimum supply flow rate of small bore journal bearing under starved lubrication. In this study, to investigate the optimum supply flow rate, temperature distributions are measured, and cavitations are observed when supply flow rate is increased and decreased under the starved lubrication. In addition, vibration experiment is done to determine the stability of the bearing. In the results of temperature distribution, the area decreasing the temperature is appeared because cavitations are generated in the area. The result of difference between the maximum and minimum temperatures for decreasing supply flow rate is larger than the result of case of increasing supply flow rate. Moreover, in the case of decreasing supply flow rate, the maximum temperature is raised rapidly below flow rate 0.55 X 10^-6[m^3/s]. However, for increasing supply flow rate, oil whip occurred by external forces. As a result, it is concluded that the area of optimum supply flow rate is from 0.55 X lO^-6[m^3/s] to 0.92 X lO^-6[m^3/s].

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Taperd rollor bearings used for differential gear of an automobile. This bearings can support heavy radial and thrust loads. In the bearings, there exists area of rolling contact and slide contact. For that reason this bearings is wear away and bearing width is decreased. This is called "bedding-in pattern". Taperd rollor bearings need above a certain pre-load for normal operation but bearings is decreased pre-load and damage to the machine because bearing width is decreased by this "bedding-in pattern". This study purpose is clear up the relation between displacement of bearing width and pre-load, and make about we can estimate for the pre-load after bedding-in pattern.

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Although giving proper fastening force to the screw fastener of a machine part is important, it is not easy to determine it. Therefore, there are several the fastener control methods and an especially comparatively easy torque method is mostly used among them. The torque method is affected by the friction of a contact part, and fastener is performed using the torque coefficient as an index. In this report, the equipment which doesn't depend on an expensive fastener testing machine is devised and made. Then the coefficient of friction of a thread face and bearing surface part, which governs a torque coefficient, is measured and calculated.

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Walking assistance is necessary for the elderly and patients who rehabilitate paralysis of apoplexy. In order to meet the social requests, a walking assistance apparatus used a spatial parallel link mechanism has been developed. Without making special constraints on person's legs the proposed apparatus can assist whole legs of a person including soles. And the aim for walk reconstruction of the paraplegic by using the impedance control the walk trajectory. As a next step, the developed torque control method to use for a walking assistance of the elderly person or a trainer who could independently walk. To calculate supporting torque using acceleration of leg points and we attached acceleration sensors to an ankle and a hip joint of the device. In the case of the beginning to walk acceleration does not occur, Therefore we suggested the method to using a template of acceleration. We confirmed the effectiveness of the method from the experiment torque data, which agreed well with the calculated data taken into account the dynamics of both the device and the sensor.

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It has been reported that the carbon nitride (CNx) coating was the super-low friction in which friction was less than 0.01, and it attracts attention as a wear resistance and low friction material. When forming a CNx coating with Ion Beam Assisted Deposition (IBAD), it turns out that to obtain coating thickness higher than 1 mm, deposition time should be long, then surface roughness became large with several size droplets. So, in this research, to clarify the effect of electron beam power to generate droplets, we varied 5 different filament current to irradiate electron beam to carbon target. As a result, the droplet height decreased with reduction of filament current density. In the case of friction tests of CNx coating which were high amount of droplet one and low one were carried out in PAO lubrication condition, the average friction coefficient of high amount of droplet showed around 0.075, on the other hand, the average friction coefficient of low amount of droplet showed 0.059.

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Recently, the flight mechanism of dragonflies has been focused on. Because dragonfly has some high flight ability such as high speed flying, high-speed turning, high robustness and high energy efficiency etc.. However, the flight mechanism of a dragonflies has not been understood sufficiently. Especially the function occurrence of lift and thrust force mechanism of dragonfly is not sufficient to clear. The purpose of this study is to clarify the dragonfly's aerodynamic characteristics. Therefore, in this study, we focused the generation mechanism of lift force and thrust force using by the simulator which imitates motion of dragonflies. Then, we examined the generation mechanisms of lift force and thrust force to clarify the mechanism. We had clarified by experiments the generation mechanism of lift force and thrust force.

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CNx (Carbon nitride) coating is one of the attractive materials that satisfy both relatively high hardness and low friction coefficient. In our previous work, Si-CNxHy coating, which was deposited by using a PECVD apparatus with Ar, CH_4, N_2 and TMS (Tetramethylsilane) employed as precursor gases, showed a very low friction coefficient of 0.009 against a Si-CNxHy-coated ball; however, substrate temperature exceeded 200°C above which low-temperature tempering steels are softened. Thus in this work, substrates (SCM415, JIS) were cooled during Si-CNxHy deposition for preventing unexpected tempering at more than 200°C, and the effect of the cooling on the substrate hardness, and the hardness and deposition rate of Si-CNxHy coating was investigated. Si-CNxHy coatings were deposited on substrates for 20 min at a gas pressure of 40 Pa, a microwave peak power of 900 W, and gas flow rates of 10, 2, 15, 0.6 seem in Ar, TMS, CH4, N2, respectively. The microwave was applied in a pulsed manner where the duty ratio was controlled in 40 %. The different 4 Si-CNxHy were synthesized at substrate bias voltages of -300, -400, -500, and ?600 V. The maximum temperature of substrate was decreased from 270°C without cooling to 140°C with cooling, where the substrate hardness after deposition was not changed with cooling and decreased from 698HV to 550HV without cooling. The hardness and deposition rate of Si-CNxHy coating were decreased and increased, respectively, by cooling. The atomic composition in the Si-CNxHy films coated at -400V with and without cooling was investigated by using ERDA and XPS, showing that the ratios of (Si+C) and H were decreased and increased, respectively, by cooling.

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Ionic liquids are expected to be used as new high-performance lubricants because of their low volatility, high thermal stability and high oxidation stability. It is well known that halogen-containing ionic liquids exhibit excellent lubricity for metals. However, there is a concern about the corrosiveness of ionic liquids, which is lubricity for metals than halogen-containing ionic liquids, which is caused by the formation of halogen halides. On the other hand, halogen-free ionic liquids exhibit inferior lubricity for metals than halogen-containing ionic liquids; however, they do not cause any remarkable corrosion effects. In this study, the lubricity of halogen-free ionic liquids- [EMIM][DCN] and [BMIM][TCC] - against hard coatings and ceramics was evaluated using an SRV sliding tester. Halogen-free ionic liquids showed better lubricity against CrN, H-free DLC, PVD-DLC and all ceramics than that of PAO. [EMIM][DCN] exhibited a better wear reduction than [BMIM][TCC] on CrN, and its friction coefficient was higher than that of [BMIM][TCC]. Ionic liquids exhibited excellent lubricity for sintered ceramics, and the lubricity is supposed to depend on the chemical effects rather than the physical ones of the ceramics like surface roughness or hardness. [EMIN][DCN] exhibited lower friction coefficient against DLC coatings with less hydrogen concentration. From XPS and TOF-SIMS analysis, molecules of [EMIM][DCN] were observed on the sliding surface of H-free DLC.

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VSM (V-shape 2-bolt clamped langevin type transducer ultrasonic motor) is a kind of friction drive devices. It has been expected as a promising actuator for high speed- and ultra precision- positioning system. It is, however, required severe feedback control for its stable positioning since the driving force of VSM operated in ambient air is not stable well. So, the objective of this study is to clarify the reason of unstable driving in air and propose the guideline for stable positioning. To understand the mechanisms, driving tests were performed both in air and vacuum. In air condition, unstable driving behavior could be observed. On the other hand, driving behavior was stable in vacuum. Optical microscopic images of driven plate indicate that some materials are adhered at the edge of the area driven in ambient air but such thing could not be found in the area driven in vacuum. Possibly, the adhered material reduces the friction force, which leads to the unstable driving force. For the positioning, value of positioning error changes as increase the number of positioning tests when driven in ambient air, while it is almost the same in vacuum for all number of steps. This indicates that unstable friction force may cause the unstable value of error.

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Carbon fiber reinforced plastics (CFRPs) are promising materials because they are light weighted and anti-wear performance depending on the microstructure of CFRP. We have reported friction properties of CFRPs previously, and showed that low friction coefficient of 0.12 could be achieved when carbon fiber reinforced polyetheretherketone (PEEK-CF) was sliding against SiC, which open the perspectives of low friction system with the combination of PEEK-CF and ceramics. However, such low friction mechanisms and wear properties of PEEK-CF against ceramics have not been understood yet. The objective of this study is to clarify low friction mechanisms and wear properties. In this study, we prepared various types of disks including SiC, Si_3N_4, Al_2O_3, PEEK and PEEK-CF. And, PEEK-CF was used as a pin. The various combinations were investigated to find the best combination in terms of low wear rate. What we found is that low wear rate could be obtained when PEEK-CF was sliding against ceramics disks with N_2 gas blow condition. As a characteristic feature, some small pieces of the material were transferred from the pin to the ball. Raman spectroscopy revealed that the spectrum of the materials on the surface of the ceramics disks is very similar to the one of carbon fiber in PEEK-CF, which indicates the carbon layer can reduce the friction and wear of the pin.

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In order to improve the precious movement of machine tools, reduction of friction resistance of sliding way guide in low sliding velocity region is essential. It was reported that coefficient of friction strongly depends on sliding velocity in the low sliding velocity region under low pressure such as sliding way guide, that is, extremely low friction is achieved in very low sliding velocity when lubricants containing oleyl acid phosphate (OLAP) are used. It was considered that this low friction is brought about viscous substance derived from OLAP. In this study, factors which affects rate of formation of the viscous substance were investigated by performing sliding friction test. As a result, it was found that an amount of OLAP being present between friction surfaces and materials of sliding surfaces strongly influence on developing velocity-dependence of the friction coefficient.

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The present study describes tribological properties of textured surface fabricated with burnishing processes in lubricated condition. A journal type testing apparatus and a ductile cast iron (FCD500) journal bearing consisting from a ground finished shaft and a dimpled journal fabricated with a micro shot peened process were used for the experiment. The surface texture was formed on the shaft surface with the rolling contact of small sphere and of ellipsoidal roller. As results, the truncated micro sized groove was fabricated. The tribological properties were evaluated with various testing speed. It was found that the truncated micro groove was effective for the reduction and stabilization of the friction coefficient and that the wear loss became smaller.

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This paper presents a study of calibration method for a 6-degree-of-freedom parallel mechanism. A coordinate measuring machine (CMM) based on 6-degree of freedom parallel mechanism is considered to give higher accuracy, speed and stiffness in measurement. In order to reduce kinematic parameter errors, which is directly cause to measurement errors, a calibration is needed. In this calibration, kinematic parameter errors are identified by the least square method. However, it is difficult to perform a calibration when using a high accuracy angle measuring device with small angle range. In this research, a calibration method is performed by least squares method so that the position error of ballplate measured by CMM and the angular error of the end effector is minimized. The measuring points are increased in the simulation, under the limitation of the small angle range of the end effector. The simulation results shows that by adding measuring points from 66 to 132, the parameter error, the position error of ballplate and the angular error of the end effector are reduced from 1264um_RMS to 37.3um_RMS, from 568.3 um_RMS to 1.8 um_RMS, and 116.2 um_RMS to 0.1 um_RMS, respectively.

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Recently, the need of colonoscopy is increasing because of the rise of colonic diseases including cancer of the colon. However, current colonoscopy depends on doctor's skill strongly. Therefore, a large intestine endoscope that can be inserted without any special techniques of doctors with high safety is required. In the previous research, the prototype variable stiffness endoscope that changes own stiffness partially by air pressure was developed. In this report, an evaluation phantom which has sensors to measure load to the intestinal wall has been developed. In addition, the variable stiffness endoscope has been improved. Using it, we have investigated the relation between stiffness change pattern and load to intestinal wall experimentally. From the experiments optimum stiffness change pattern to reduce the load in colonoscopy has been derived.

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Island-shaped self-assembled monolayer (SAM) of octadecyl-trichlorosilane was repeatedly slid with the atomic force microscope (AFM) to clarify the deformation and fracture behavior, employed as model for localized adsorption films in practical boundary frictional conditions. There were two types of the island-shaped adsorption film; one is well-assembled monomolecular film with 2.2nm in thickness, another is less-assembled monomolecular film with about 0.8nm in thickness. The well-assembled monomolecular film can respond like as solid film with large rigidity, and then, has Coulomb frictional property. On the other hand, the less-assembled film can respond like as elastic material if relatively low normal load is applied. In this case, friction coefficient also linearly depends on the applied normal load. Moreover, if the normal load increases by certain level, kinetic response of the film indicates plastic behavior. That is, there is irreversible reduction of film thickness due to the applied load and its associated increase in friction coefficient.

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The present study describes an applicability of shot peening treatment using soft impact media to improve surface strength properties of hardened chromium alloy steel. The shot peening treatment was carried out with a developed peening apparatus consisted from a double walled nozzle and a rubber ball enclosed media tank. Steel based fine particles having various harnesses and same sizes were used as the impact media. It was found that the peened surface with soft media was hardened despite that the increase of the surface roughness was small. The surface fatigue properties evaluated with a thrust type rolling contact experiment showed that the peeled area of the peened surface becomes smaller. Therefore, it was estimated that the shot peening treatment with soft impact media is effective to improve the surface strength properties.

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This paper presents a kinematic calibration method using a three-dimensional ball plate calibrated beforehand with an accurate conventional coordinate measuring machine. The least square method using Jacobian matrix estimates the kinematic parameters so that the ball position errors obtained by measuring the ball plate are minimized. Moreover this paper describes a compensation method for elastic and thermal deformations of the machine frame supporting the mechanism of the parallel kinematic machine (PKM). The forward kinematics of the hexapod mechanism calculates displacement and attitude variations of the base platform during operation from these measured displacements. Consequently, coordinates of the PKM's end effector can be compensated by the dimensions, the displacement, and the attitude of the base platform during operation. From the experimental results, it is found that the position error of the ball plate has decreased. Peak-to-peak error and RMS error became smaller, from 484 um_p-p to 6 um_p-p, and 141um_RMS to 1.07um_RMS, respectively.

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The present study describes cycles to failure initiation in endurance tests for carbon and glass fiber reinforced phenol gears (CFRP and GFRP). They are determined under the severe operating conditions, i.e., high rotation speed and high temperature. As a result, CFRP gear pairs showed lower cycles to failure initiation as operating temperature increasing. Although GFRP gear pairs also showed lower cycles as temperature increasing, the highest cycles was obtained under the maximum temperature (180°C ). All results except for under maximum temperature (180°C ) showed CFRP gear pairs have greater endurance than GFRP ones. The CFRP used here includes not only carbon fibers but also organic fibers. These organic fibers could make cycles of CFRP gear pairs lower.

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This paper discusses the control techniques of the force feedback device that is switchable between contact and contactless. The force feedback device that we developed in this study can present the sense of force to a fingertip. Contactless control, which keeps space between part of the force feedback device and the fingertip, allows the user to avoid contact with the device when force feedback is not needed. The device is equipped with a photo-interrupter to keep a certain distance from the fingertip and a servomotor for the drive. One switches from contactless control to contact control when force feedback to the fingertip is needed. The force feedback device measures the stress that the fingertip put on the device by means of a pressure sensor and calculates from the results the displacement, using the finite element method. Combining the displacement with the drift angle of the servo motor produces virtual rigidity. Moreover, we developed the force feedback software to display an elastic interaction according to the displacement. The experimental results revealed that the force feedback device can present the difference of hardness.

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Using aspherical lens contribute to downsize the optical equipment. But, manufacturing process of the molds has a problem. Form errors are generated during precision cutting process, and the form errors are inherited to precision polishing process. To eliminate the form errors, it is necessary to measure the cutting surface, but there are no useful methods to measure such surface. In this study, we developed a new method of measurement of the surface profile of the precision molds using the laser microscope having a wide field of view. Observing concavities of the test mold with laser microscope having the wide field of view, it was revealed that we can observe the interference fringes even on rough surface. In addition, we can construct the 3 dimensional profiles of the concavities by thinning-processing and least-square method.

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DLC (Diamond-like-carbon) films are used in various fields because of their excellent tribological properties. Although there are many evaluation techniques for the surface strength of DLC films, those are not sufficiently established now. Versatile and reliable techniques for evaluation of hard thin coatings are necessary for evaluating the DLC films. We have proposed a new type of micro slurry-jet erosion (MSE), i.e. a solid particle impact erosion test for swift evaluation of surface strength properties of hard thin coating. By slurry jet, 1.2 um alumina particles were impacted at high velocity perpendicularly to the coating material. In this paper, we evaluated the surface strength of several DLC films by MSE method. And we measured the hardness of DLC films by nano-indenter. In order to consider the wear mechanism, the micro-topography of the worn surfaces of DLC films was observed by AFM. As a result, we can evaluate the surface strength of DLC films clearly by MSE method, the wear rate (um/min] increase with increasing hydrogen content of DLC film. And furthermore, MSE test could evaluate the surface strength of DLC films more clearly than nano-indentation test.

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Hydraulic systems have features of compact and high output power. However, in recent year, further downsizing and higher output power of hydraulic equipment have been demanded. As a result, operating pressure of hydraulic systems has been increasing and cavitation has significantly occurred with increasing pressure. The purpose of this study is to reduce the cavitation occurrence by eliminating bubbles in oil at high pressure condition. In this paper, the relation between the amount of the cavitation erosion and the bubble elimination is experimentally investigated.

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Laser processing is the necessary technology for the high speed cutting about materials. However, there are heat-affected zone at the cut surface, and it causes the reduction of the material strength. In this study, the cutting characteristics of carbon fiber reinforced plastic (CFRP) with nanosecond pulsed Nd:YAG laser beam are investigated. The effect of cooling water on the heat-affected zone at the cut surface is evaluated. The eliminated volume of CFRP in water environment was smaller than that in air environment due to the thermal expansion by water. However, the cut-off of the CFRP with a thickness of 1 [mm] was achieved without any heat-affected zone at the cutting surface although the input energy to the CFRP was larger than the air environment.

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An ultrashort pulse laser is able to micro laser machining with high precision. The purpose of this study is to process the through-holes with a diameter less than 50fim and aspect ratio more than 10 using an ultrashort pulse laser. We have developed a trepanning system, enabling the adjustment of the inclination angle. This report outlines about high-aspect-ratio microdrilling using this system.

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Recently, in sheet metal forming field, it is required to make variety of shapes in small quantities for small batch products and made-to-order products. Incremental forming which can form sheet metal by relative movement of simple tools instead of specific die set has been developed for such demands. On the other hand, from a viewpoint of weight saving, Mg alloy sheet and A1 alloy sheet attract attention. Warm forming is necessary to form these lightweight materials because their formability is limited at room temperature. Therefore, a combination of incremental forming and warm forming is an attractive method to form such sheet metals in small quantities. In this study, incremental forming system with local heating by laser irradiation was newly developed to form lightweight hard-to-form alloy sheets in small batches. Relationships between laser irradiation conditions, sheet-surface temperature and formability for Mg alloy (AZ31B-O) sheet at several forming speeds were examined. The results show that the developed incremental forming system can form the sheet metal successfully and forming limit of the sheet increased with increase of sheet-surface temperature by laser irradiation.

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Laser beam is prospective as a heat source in the heated machining process of 'difficult-to-cut materials'. Because the heating decreases the strength of material, therefore high productivity could be achieved if the thermal wear of tool would be reduced. In this study, laser heating is applied for the milling process of titanium alloy which is well known as one of difficult-to-cut materials for its low thermal conductivity causing the thermal tool wear. And temperature of cutting edge of tool is investigated by two-color pyrometer using optical fiber which realizes measuring of the rapid temperature change in small region such as cutting edge of the tool. The cutting force is also investigated to estimate the effect of softening of material caused by laser heating process.

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In this paper, the measurement of dynamic stress generated in the Ti0_2 suspension induced by Nd:YAG laser beam irradiation is proposed. The dynamic stress generated in the Ti0_2 suspension by using elastic wave propagation in the cylindrical long bar made of aluminum alloy is measured. The laser induced stress intensity is evaluated from the dynamic strain measured by small semiconductor strain gauges. As a result, the dynamic stress induced by laser beam irradiation is depended on powder type and particle diameter. When the peak power is P = 4 kW, the dynamic stress generated in the TiO_2 suspension with a particle size of 0.02 um reached the maximal value, and it was 1100 Pa.

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Recently, the complicated shape molds can be manufactured at a shorter production time and lower cost by rapid tooling (RT) technology. Additionally, in injection molding, the air vent system using porous material is known as effective way to exhaust gas pressed into mold and improve the burning and short shot of molded components. Thereat, applying that air vent system to injection molds manufactured by RT technique is now expected. In this report, the fabrication of air vent structure which is obtained by an additive manufacturing system is proposed. The influence of laser conditions on the porosity and the permeability of the consolidated structure are investigated experimentally. As a result, the porosity and permeability are increased relative to laser scan speed. The porous part of sintered structure becomes permeable over 25% of the porosity.

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PcBN cutting tools have excellent characteristics such as large hardness and low chemical reactivity, so they have the potential to replace high precision grinding of hardened steel with high precision cutting. However, there are some problems if diamond grinding is employed as forming method for PcBN cutting edge; such as chipping, falling a cBN particle off and forming pre-crack. In order to solve these problems, PLG (Pulse Laser Grinding) was adopted to form a PcBN cutting edge and performances which were demanded as a cutting tool were investigated. Firstly, the cutting edge was measured by contact-type profilometer. As a result, cutting edges processed by the PLG are similar or sharper than that by conventional diamond grinding. Secondly, the hardness of processing surfaces was measured by micro-Vickers hardness tester. The hardness increases by about 10 percent after PLG. Lastly, the frictional test was conducted by lateral force microscopy. Coefficient of friction of a PLG'ed surface decreases by half of the ordinary surface because of generation of hBN or TiB_2 during PLG Processing. Depending on these advantages of PLG, the tool processed by PLG can demonstrate a good performance rather than a tool processed by diamond grinding under the condition of high precision turning of hardened steel with 58HRC in hardness.

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A CAM system has become absolutely essential for an application of multi axis machine tool and for an application of industrial robot. However, most of the systems are commercial software and the algorithms are highly confidential. Althouge the developpers for such applications are using API included in commaercial CAD systems, limitations in the environments and for the functionalities are hard to be solved. Therefore, the study deals with the proposal of construction of platform-compatible and open-source CAM kernel for anyone who want to develop, release and share to raise the standard of CAM development mainly in educational field.

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