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Satoki FUJISHIRO, Shigeka YOSHIMOTO, Kazuyuki YAGI
Article type: Article
Pages
95-96
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Aerodynamic foil bearings have been successfully applied to micro-gas turbines used for distributed electric power supply. Aerodynamic foil bearings have such advantages that they can operate at high temperature and high speeds. In this paper, the static characteristics of aerodynamic gas foil journal bearings at high speeds are investigated theoretically and experimentally, using a spirally-wound foil bearing with half-spherical bumps and the usefulness of this type of foil bearing is clarified.
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Naoki SUGANUMA, Shigeka YOSHIMOTO, Shinsuke DAMBARA, Kazuyuki YAGI
Article type: Article
Pages
97-98
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes the characteristics of circular aerostatic thrust bearing with a single air supply hole. In case of high air supply pressure or large bearing clearance, it was reported that shock wave occurs and forms complex fluid structure in the bearing clearance. However, it is very difficult to obtain the information of flow structure in detail from flow visualization because of very narrow clearance. Therefore, we calculated the flow field using computational fluid dynamics (CFD), Reynolds equation and supersonic model. In addition, we measured pressure distributions in the bearing clearance. It was consequently found that pressure distributions obtained by CFD are good agreement with experimental data and that CFD is useful for prediction of pressure distribution in bearing clearance of circular aerostatic thrust bearing.
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Masaaki MIYATAKE, Shigeka YOSHIMOTO, Kazuyuki YAGI
Article type: Article
Pages
99-100
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Recently aerostatic porous bearings have been used in ultra precision machine tools and precision measuring equipments because they have higher stiffness and damping coefficient than another types of aerostatic bearings. Moreover, aerostatic bearings with porous restrictor have been successfully applied to high speed spindles for drilling small holes of printed circuit-boards. However, aerostatic porous bearings are prone to cause pneumatic hammer instability. Therefore, it is considered that reducing permeability of the bearing surface layer than that of the bulk of the porous material is very effective means for avoiding pneumatic hammer instability. In this paper, the dynamic characteristics and instability at high speeds of aerostatic porous journal bearings with a surface-restricted layer are investigated theoretically and experimentally.
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Takehiro MINEMURA, Noritsugu UMEHARA, Masahiko YOSHINO
Article type: Article
Pages
101-102
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In order to evaluate surface properties as wettability and surface energy, novel surface analysis method was proposed with the observation of condensed liquid drops on the specimen in an ESEM. In the present study, indentations were made on a soda-lime glass plate with a sharp knife-edge of diamond, and the condensation of water on the glass plate as liquid drops were observed. As a result, the condensation of water was started from indentations marked on glass plate and spread to the other area. On the basis of adsorption mechanism, capillary condensation to the cracks in indentation has an important role for selective condensation to the glass.
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Akira NAKAJIMA, Toshifumi MAWATARI, Takafumi YOSHIDA, Yasuyoshi TOZAKI ...
Article type: Article
Pages
103-104
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Using a magnetized ball and hall elements arranged on the nut and the return tube, the authors measured the ball motion and the vibration of ball screw which incorporates resin retaining pieces between balls rotating at the shaft speed in the range of 120〜950rpm. The results were compared with not only the experimental results using the same type of normal ball screw but also the analytical results calculated based on the kinematic geometry of ball screw mechanisms. The ball motion in the ball screw became smooth by insertion of the retaining pieces and the vibration was fairly restrained. Especially, when the ball screw operated at a high speed, both the ball rotation and the ball circulation in the ball screw with retaining pieces were faster than those in the normal type without retaining pieces and the measured values well agreed with the analytical values.
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Katsumi FUKUDA, Takuji ITO, Mitsuo KOBAYASHI
Article type: Article
Pages
105-106
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The characteristics of resists used for fine pattern writing by electron beam lithography systems hold the key to much finer pattern writing for the semi conductor technology improvement. In this report nano indentation characteristics of PMMA resist materials were examined from the pre-braking temperature and time points of view. Although differences in nano indentation hardness were not observed above 2μN was applied, differences were observed when the load of 1μN or less was applied. Furthermore, the nano indentation hardness increased when longer pre-baking time is applied at the pre-baking temperature of 200℃.
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Hideaki KANEMITSU, Tokio KITAHARA
Article type: Article
Pages
107-108
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In order to investigate the friction characteristic of a small contact surface, we developed a Pin-on-Disk type of friction tester. Since this equipment can carry out simultaneous measurement of load and the friction force, load-friction characteristic can be obtained in one experiment. Using this equipment, we investigated the friction characteristic of copper-S45C and aluminum-free machinig steel. It was clarified from the experiments that friction coefficient decreases with the increase in contact pressure.
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Tetsuya OKUMURA, Joichi SUGIMURA, Yuji YAMAMOTO
Article type: Article
Pages
109-110
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Molecular dynamics (MD) simulations were conducted in order to study effects of polar groups in lubricant molecules on the ultra-thin film lubrication. Lubricants were blends of n-hexane and 1-hexanol with several concentrations, which were confined and sheared by flat iron surfaces. Hexanol molecules formed hydrogen bonds in lubricant films. Interaction forces between hexanol molecules are stronger than that between hexane molecules due to hydrogen bonds. Larger concentration of hexanol in lubricant caused less slip between lubricant molecular layers, which resulted in higher traction between the surfaces.
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Takuma TERUI, Keiji KATANO, Takashi TAMURA, Akira IWABUCHI, Tomoharu S ...
Article type: Article
Pages
111-112
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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We have been developing a micro reducer with small, high accuracy and low cost. This micro reducer is composed of plastic plain bearings and mold plastic gears with shaft. One of the problems in this R & D is how to reduce friction and wear between mold plastic plain bearings and mold plastic plain shafts. We try to improve this problem by the combination of materials and lubricants. Another problem is reduction of friction and wear between the plastic plain bearing and metal shaft. In this paper, effects of lubricants and surface coatings for the plastic bearings and the metal shaft are examined, and high transmission efficiency for the micro reducer is described.
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Shinsuke SYOUJI, Masami HARADA, Jyuutaro TSUKAZAKI, Hiroshi YAMAMOTO
Article type: Article
Pages
113-114
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper presents an experiment result of a load carrying capacity, center locus and friction torque of a bearing with magnetic fluid. The following results are obtained. 1) Magnetic fields make the pressure of the lubricant film, load carrying capacity and attitude angle increase. 2) Even if a shaft does not rotation, the magnetic fluid bearing flout. 3) Load carrying capacity becomes large by influence of a magnetic field. 4) As for the load carrying capacity, small bearing of a bearing clearance is big. 5) Load carrying capacity of the bearing becomes big by influence of a magnetic field in low rotational speed.
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Takashi NAKAMURA, Fumihiro ITOIGAWA, Takashi NORIHISA, Kazutaka WATANA ...
Article type: Article
Pages
115-116
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In a high speed spindle assembled in machine tools, ball bearings has been often lubricated with a minute amount of lubricant to reduce a temperature rise due to viscous drag and churning. Small lubricant supply rate may give rise to a starved lubrication condition, especially in a high speed condition. To avoid fatal seizure of the bearing, lubricant behavior in the vicinity of ball-race contacts must be clarified in the above situation. In this report, lubricant walls at the sides of a contact footprint, called side bands, is noted because there exists significant portion of lubricant in these walls. It is assumed that the lubricant in these walls can re-flow to the contact area if only a small misalignment between two successive ball tracks. Effect of the re-flow from the walls on central film thickness is investigated by interferometric measurement.
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Keiichi NAKAO, Kikuo OKAMURA, Kazuhiko SAKAGUCHI, Takashi MATSUOKA
Article type: Article
Pages
117-118
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In this research, it is the purpose to solve the power transfer characteristic of 3K-type CVT. As a concrete method, at first, the shear characteristic of traction fluid under high Hertz pressure is shown by a shear model of traction fluid in EHL contact area, and traction power is computed. Next, the torque transfer efficiency in each contact area and speed transfer efficiency are computed using the concept of a force pole, and the power transfer efficiency in each contact area is searched for by using these. And the theoretical power transfer efficiency of 3K type CVT is searched for by substituting this result for the efficiency formula of a planetary mechanism. Moreover, a calculation result is compared with an experiment result in order to investigate the usefulness of this analysis.
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Hideaki YAMAUCHI, Kazuhiko SAKAGUCHI, Takashi MATSUOKA, Masayoshi MURA ...
Article type: Article
Pages
119-120
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In this research, investigation was made on the traction characteristics under wide-ranging mean Hertzian pressure from 0.7GPa to 2.3GPa with using various axial direction curvature steel specimens. And then, same tests were carried out under test conditions for several types of traction oil. As a result, in the case of the Santotrac40 and KTF1,it was shown that the maximum traction coefficient increased slowly with the increase of mean Hertzian pressure at the first stage of that traction coefficient curve. After then, that traction coefficient curve gradually decreased. And, the numerical calculation was carried out by the Tevaarwerk's elastoplasticity shearing model with some oil film properties in EHL state reported by another researches.
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Tomohiro KIMURA, Masayoshi MURAKI
Article type: Article
Pages
121-122
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Triction characteristics of polymer solutions were determined at a rolling speed of 0.05m/s and 0.4m/s over a range of temperature with a disk on ball type EHL tester using steel disk. As the temperature is raised at a high rolling speed, the traction curves on the whole decrease, while at a low rolling speed, the change in traction with temperature depends upon the type of polymer. When the coefficient of traction at a slide/roll ratio of 50% was plotted against temperature, it increased with temperature for PMA containing oil and the base oil, while it first decreased and then after reaching the minimum it increased for DPMA containing oil. It was inferred that dispersant group of DPMA contributed to the friction reduction due to thick film formation in EHL contact.
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Hiroki KAGEYAMA, Masayoshi MURAKI
Article type: Article
Pages
123-124
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A disk-on-ball type EHL tester was built as a trial to study the traction characteristics under EHD conditions. The performance of the tester was confirmed using the commercially available traction oil for automotive traction drive. The traction coefficient decreased with increasing temperature while it was little affected by change in contact pressure. This is probably because an EHL oil film behaved as a plastic solid. In addition, the influence of skew component was found to be critical. The experimental results were in good agreement with the previous reports.
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Satoshi MOMOZONO, Motohito KURAKAKE, Keiji KYOGOKU, Tsunamitsu NAKAHAR ...
Article type: Article
Pages
125-126
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Investigation on friction coefficient between steel and fibers as a part of paper-based clutch facing was carried out under different normal loads and sliding velocity using friction tester that steel rods nipped fibers in dry or lubricated condition. Fibers are made of cotton, aramid and carbon. Base oil is mineral oil. Lubricant additives are oleic acid, ZDTP, Ca-sulfonate and succinimides. Friction coefficient under dry conditions show lower than that under lubricated conditions. Friction coefficient show large value under small load and lubricated conditions, and the "μ-v" slope show almost constant in all conditions.
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Masahiro FUJII, Akira YOSHIDA, Hideaki ORITA
Article type: Article
Pages
127-128
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The authors examined friction and wear characteristics of electroless Ni based alloy platings under oil lubricating condition with ring-on-disk test machine. Electroless Ni-P alloy plating, electroless Ni-B alloy plating and electroless Ni-P-B alloy plating were employed. In case of the combination of the electroless Ni-B alloy plating and the electroless Ni-P-B plating the wear occurred in the lowest contact pressure. The friction behavior was the most stable in case of the combination of the electroless Ni-B alloy plating and the electroless Ni-P alloy plating. The friction coefficient of the self-mated electroless Ni-P-B plating was small, while the wear was comparatively large.
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Masahiro FUJII, Akira YOSHIDA, Yoshiomi SHIMADZU
Article type: Article
Pages
129-130
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In order to investigate friction and wear characteristics of the thermal diffused Sn plated stainless steel in vacuum, ring on disk tests were performed. In case of the tests in vacuum the friction coefficient at high temperature was slightly smaller than that at room temperature, while the specific wear rate at high temperature was greater than that at room temperature. In case of the tests in vacuum the friction behavior was stable and the wear was small after the wear depth was equivalent to the thickness of the modified layer. On the contrary both the friction coefficient and the wear were increased with increasing sliding distance and the wear exceeded the modified layer.
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Hozumi GOTO, Yoshifumi AMAMOTO
Article type: Article
Pages
131-132
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Pin-on-disk type wear tests of mild steel in contact with itself were conducted under unlubricated conditions in moist air to investigate the effect of a change in load on the transition behavior between severe and mild wear. Machines in operation are usually subjected to varying loads. In this study, two contact load levels were used as a simple varying load condition. The load was changed in a step-wise manner between the low and high levels once during certain tests. After oxidized wear surfaces have been formed under mild wear at the low load during the first stage, the wear mode changes to "quasi-mild wear" having a low rate at the high load in the final stage. Oxidation rate of the wear surface under mild wear in the first stage is related to the transition to quasi-mild wear.
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Yasuo KONDO, Takao KOIDE, Kouitsu MIYACHIKA, Fumio OBATA, Yoshiki YAMA ...
Article type: Article
Pages
133-134
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Friction and wear characteristics of Fe_2O_3,Fe_3O_4,reduced iron and α-FeOOH were experimentally examined in the absence of lubricant. Each iron oxide showed a specific friction and wear motion. Fe_2O_3 showed the lowest friction coefficient and generated no frictional noise under the entirely test condition. Fe_3O_4 had an optimal friction speed and load to minimize the friction coefficient. The frictional noise, unlike Fe_2O_3,was generated at every test condition. While the friction coefficient of reduced iron was a little larger than that of Fe_2O_3 at lower friction speed and load. As the friction speed and load increased, the friction coefficient gradually approached that of Fe_2O_3 due to the formation of Fe_2O_3 film along the sliding surface. α-FeOOH showed no lubricating ability.
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Takayuki TOKOROYAMA, Noritsugu UMEHARA, Seiichirou HIRONAKA
Article type: Article
Pages
135-136
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Important role of transfer layer from CNx coatings to Si_3N_4 ball were already proposed in the previous our study on ultra low friction of CNx coating sliding against Si_3N_4 ball in Nitrogen. In the present study, in order to know the effect of the presence of CNx coating to the mating surface, CNx coated Si_3N_4 balls with various thickness of CNx were prepared and used for pin-on-disk friction test against CNx coatings in Nitrogen. As a result, minimum friction coefficient of 0.013 was obtained in the case of 20nm of thickness of CNx on the ball. It was confirmed that transferred CNx on the Si_3N_4 ball is more effective than the coated CNx for ultra low friction in Nitrogen.
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Masabumi MASUKO, Takeshi OHKIDO, Akihito SUZUKI, Takafumi UENO
Article type: Article
Pages
137-138
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Zinc dialkyldithiophosphate (ZnDTP) is a well-known multi-functional additive for lubricating oils having superior oxidation inhibition and antiwear performance. Almost all the engine oils contain ZnDTP because no additive has been found to have better performance, yet. On the other hand, since it has been pointed out that ZnDTP poisons exhaust catalysts, reduction of the ZnDTP concentration in the engine oil has become an important task without loosing the antiwear performance. Friction and wear characteristics of intentionally deteriorated-ZnDTP that simulated used-engine-oil were studied using a four-ball tribometer. Both sec-C6 and prim-C8 ZnDTPs were used and they were degraded by reacting with cumene hydroperoxide (CHP). Fresh ZnDTP-containing oil showed lower wear and higher friction than those with the base oil. However, the anti-wear performance was gradually decreased with increasing ZnDTP degradation, and appreciable wear increase was observed after dissipation of ZnDTP. Beyond this point, further degraded oils showed larger wear and lower friction than those with the additive-free base oil. In other words, simulated used-oils were found to accelerate wear but to decrease friction. ZnDTP produced various kinds of phosphorous-containing compounds after reacting with CHP. Some degradation products from ZnDTP accelerated wear that might due to corrosive wear by excess reaction of surfaces with sulfur in the degraded compounds.
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Naoharu UEDA, Zhrgang WANG, Tamotsu NAKAMURA, Kuniaki DOHDA
Article type: Article
Pages
139-140
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In recent years, manufacturing engineering for no lubricant metal forming process has been desired from the uneasiness for the global environmental safeguard. From this viewpoint, the lubricant pre-coated steel sheet consisted of resin layer with wax particles has been developed. This research was carried out to investigate the friction behavior of the lubricant pre-coated steel sheet by the method of Bowden-Leben friction testing. The friction behavior was investigated under the conditions that normal load, sliding velocity, temperature and spherical radius of the pin were changed broadly.
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Munekazu NISHIKAWA, Junji SUGISHITA, Hatsuhiko USAMI, Kenji FUJII
Article type: Article
Pages
141-142
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Isami Nitta, Hirotoshi TERAO, Takuya Seshita
Article type: Article
Pages
143-144
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In case of a thermal transfer printer, it is important to place the heater of the thermal print head at the position where the contact pressure is most high. So it is necessary to clear the contact pressure between an inkribbon and a thermal print head. The viscoelastic properties of the ink, PET and platen rubber were measured with a rheometer. The contact pressures on the thermal print head were calculated by FEM. The contact pressures under consideration of viscoelasticity were different from those calculated by elastic analysis. To examine of the effect of the contact pressure to the print quality the optical densities were measured with the heater positions of the thermal print head changed. The optical densities were changed with the heater positions. It can be found that the optical densities decreased with the calculated contact pressure.
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Joichi SUGIMURA, Taisuke MARUYAMA, Tsutomu SATO, Yuji YAMAMOTO
Article type: Article
Pages
145-146
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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An apparatus has been designed and built which is able to measure road surface roughness and tire/road traction at the same location on pavements. This paper briefly describes the system, and shows some example data taken on bricks in dry and wet rolling/sliding contact conditions.
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
Pages
147-148
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In fitting a shaft and rolling bearings or gears, the standards of fit quality are basically established by JIS according to its application or purpose. However it is difficult to select the most suitable fit quality because the work pieces are machined with some tolerances of profiles and dimensions, and these tolerances influence the contact pressure and deformation. A purpose of this study is the development of a pipe having grooves in its inside. In this study, stresses and displacements in a ring and pipe in fitting with interference are analyzed by means of finite element method with various types of groove and amounts of fitness.
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Keiji IMADO, Masuji NAGATOSHI, Atsuyoshi MIURA, Hioomi MIYAGAWA
Article type: Article
Pages
149-150
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A method of calculation for contact pressure in conformal contacts was studied. In elastic contact analysis, the Hertzian theory is well known. But the Hertzian theory is hardly applicable to a problem of an extreme conformal contact condition, such as ball joints or journal bearings. Providing a relation between contact pressure and interference depth of the original configurations, contact pressure was calculated and compared with the FEM analysis. This method is analogous to the calculation of load distribution in radial ball bearings. The accuracy of the method was numerically evaluated by simple problems. It was confirmed that the accuracy of this method for contact pressure was enough for practical use.
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Masayuki KURITA, Yasuhiho NAKA, Junguo XU, Mikio TOKUYAMA, Hiroshi FUK ...
Article type: Article
Pages
151-152
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The rapid increase in the recording density of magnetic disk drives has required the flying-height of magnetic head sliders to be decreased to approximately 10nm. However, under such low flying-height conditions, heat due to high-frequency current in the writer coils and rise of the surrounding temperature cause local protrusion of head elements. This protrusion makes the flying-height less than the design value and reduces the safety margin for the head/disk interference. In the current work, heat transfer in the head slider and thermal deformation of the head were numerically simulated. The simulated temperature distribution agrees well with the experimental result measured by infrared microscope. A parameter survey revealed some important design guidelines for making a head that suffers minimum protrusion (that is, a low-protrusion head) : (i) reduction of alumina-basecoat thickness decrease the protrusion; (ii) a silica-alumina-compound cover layer is effective because of its low coefficient of thermal expansion; and (iii) an additional bonding between the trailing end of the slider and the suspension cools the writer coil.
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Eika TAKAMI, Nobuyuki IWATSUKI, Kouichi MORIKAWA
Article type: Article
Pages
153-154
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Aiming to synthesize new mechanisms, new kinematic pairs with multi-DOF were proposed. In the pair, one element moved along a spatial curve with rotations about three axes relative to the other element. Spatial curves were classified with respect to their curvature and twist ratio. The condition that the one element can move along a spatial curve relative to the other element was derived. Consequently only a straight line, a circle and a constant spiral were obtained as a suitable spatial curve. Three kinds of pairs with 1,2 and 4 DOF which were composed of a spiral tube and a block with rectangular or circular closs-section were synthesized and built with a rapid prototyping method.
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Takashi NOZAKI, Takeshi KOHARA
Article type: Article
Pages
155-156
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The internal forces of a constant velocity joint (CVJ) have become more apparent with CVJ researches. However, experimentally validated data of the internal forces have not been available to the authors' satisfaction. Hence, we developed a test rig to measure actual internal forces acting in Tripod constant velocity joint. The stiffness of the test rig is enough to measure housing forces under the operating condition of high rotation speed and large transmission torque. In this paper, we show the influence of the crossing angle on the housing forces as well as the relationship between the induced thrust and the tangential forces acting on the roller groove.
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Bin FENG, Nobuyoshi MORITA, Shinji KITAZUMI, Takao TORII
Article type: Article
Pages
157-158
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The relations between the geometry and the dynamic characteristics for the path generation of a planar linkage are investigated, and a new optimum design method to combine the geometry and the dynamic characteristics of the linkage are presented in this paper. Design examples for the path generation are given in two cases, one is the linkage designed without considering the dynamic characteristics; and the other is the linkage considering the dynamic characteristics. The maximum error of path generation and the maximum value of the shaking force/moment are compared with two kinds of linkages. In order to reduce the shaking force/moment, the balancing is carried out for the designed linkages. Comparing two kinds of linkages, it is known that the method presented in this paper is effective for the design of planar linkage with the path generation.
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Hidetsugu TERADA
Article type: Article
Pages
159-160
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The Orthogonal Output Type Precession Motion Ball Reducer has been newly developed. The element of the reducer consists of five components; an inclined input shaft, a fixed ring, a precession motion rotor with freely rotating balls, a spherical converting rotor of the precession motion and an output ring. Especially, this converting rotor makes a precession motion around the different rotating axis, which axis is orthogonal to an input shaft. Also, the freely rotating balls are arranged on the precession motion rotor, which positions are different from the co-axial output type. In this report, the motion principle is analyzed. It is proved that the position of each ball attached on the precession motion rotor is the important parameter as like the co-axial type.
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Takaaki OIWA, Kyohei YAMAMOTO
Article type: Article
Pages
161-162
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper presents an improved touch probe system for higher sensitivity. In this system, three fiber optic displacement sensors measure displacement and direction of a tip ball of the probe. Because the measuring resolution of the displacement was less than 80nm in experiments, a probe pre-travel was determined to 100nm. The variation of the pre-travel was less than 80nm in whole directions. The measuring force was less than 0.8mN in horizontal directions, and was 11mN in vertical direction. A over travel mechanism using kinematic joint requires consideration of its repeatability.
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Norifumi Nishizaka, Nobuyuki Iwatsuki, Kouichi Morikawa, Koji Kondo
Article type: Article
Pages
163-164
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes kinematic analysis of hyper redundant robot built by serially connecting with many units with a few DOF. Each unit is a spatial parallel mechanism with 3 DOF and is composed of 2 stages connected with 3 linearactuators, 7 spherical joints and a center rod. Direct kinematic analysis was carried by solving a system of nonlinear equations on posture angles of a stage. The Jacobian matrix is derived from the derivatives of the equations. Two kinds of inverse kinematic analyses were carried out. The one was to obtain the input velocities whose square norm is minimum by using pseudoinverse of Jacobian matrix. The other was to carry out the iterative calculation so as to converge output error while output displacement was evenly distributed into each unit. Several simulation results of direct and inverse kinematics were illustrated.
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Gang Shen, Yukio Takeda
Article type: Article
Pages
165-166
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A kinematic calibration of a spatial in-parallel actuated mechanism with six degrees of freedom that has three connecting chains is discussed in the paper. With consideration of practical measurement devices, four measurement methods of displacement error for kinematic calibration are considered. Effects of the measurement methods on the quality of calibration are investigated through simulations and discussed.
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Takashi MIZUNO, Nobuyosi MORITA, Sugiaki YAMAZATO, Bin FENG, Takao TOR ...
Article type: Article
Pages
167-168
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes a new bed for human body, called a multi-pin support bed by air control. Air-cells are located lengthwise and sideways, and pins are located on a point of the intersection of air-cells. When pressures of the air-cells increase, the pins are moved up and half balls on the pins push up the back of a human body. It is able to change the magnitude of the pressure to the back and the pressure distribution by controlling the presser of the air-cells. This bed is useful for the prevention of bedsore or for the relaxation.
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Nobuyoshi MORITA, Hajime MOGAWA, Takao TORII, Bin FENG, Takashi MIZUNO
Article type: Article
Pages
169-170
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A new walking training machine is developed for the aged persons or the handicapped persons to make recover leg's function. Walking is the periodic motion using the whole body composed of the vibration of center of gravity and the bending and stretching of leg's and so on. Using this machine, the whole body is vibrated up and down by vibrating floor board. The paths of handicapped person's physical parts and the reaction forces of floor board are measured and it is shown that this machine is useful as the walking training machine used at home.
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Yuichi NAKAZATO, Takuma MIYAUCHI, Yukinori ARIGA
Article type: Article
Pages
171-172
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In this study we develop in-pipe mobile robot assuming to run in the blood-vessel. Therefore, the transfer form using the wheel would not be used, and the mechanism for the transfer by the peristalsis is adopted. And, it is not used the result which the actuator operates using the electric power. The actuator which moved by the water pressure is adopted. The robot is manufactured from the above design condition actually, and the operation is confirmed by the experiment. The experiment which run the human intravenous is not done, but it is confirmed that produced robot moved in straight pipe made of the acrylic resin of the 6mm inside diameter. And in this paper, it is reported, because going back mechanism was developed by the peristalsis using the expansion of the rubber without the wedgy leg like the convention in the advance.
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Masaru TOMIMATSU, Daiki KAMIYA, Mikio HORIE
Article type: Article
Pages
173-174
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A new surface mount system that is composed of many miniature manipulators has been proposed as a means of system down-sizing. The miniature manipulator consists of a molded pantograph mechanism, which has large deflective flexure hinges and links, both made of the same materials. A complex and dynamic force acts on each flexure hinge in the pantograph mechanism along with motion and vibration of the pantograph mechanism. Then, a dynamic stress state, a combination of bending, tensile, compressive, and shearing stress, is induced within the hinge. We set up a hypothesis that in these stresses, bending and tensile stress are the major factors in the fatigue damage of hinges. On this hypothesis, we carried out a reverse bend test under a static tensile load condition with a hinge specimen as a fatigue test. The hinge specimen is injection molded, and the material is polypropylene, polyethylene, polyamide, and polystyrene. From this test, we investigated the durability of a hinge, frequency relativity to the durability of the hinge, and the advance in damage inside of the hinge.
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Hideo NAKAMURA
Article type: Article
Pages
175-176
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In a traction drive under extremely high pressure condition, the influence of the lubricant compressive delay on traction performance cannot be ignored. It seems that the bulk viscosity of the lubricant brings the delay in response of the hydrostatic pressure to the applied normal stress. In this study, it is attempted that the bulk viscosity is measured using a compressive experimental apparatus. It is considered that measured results are fairly valid because increase in the bulk viscosity with pressure has the same tendency as that of shear viscosity. A traction map is drawn to take the influence of the compressive delay into consideration and discussed.
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Norikazu Ise
Article type: Article
Pages
177-178
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The present paper deals with tribological properties of the torque limiter adopted a hybrid system. For lightweighting, magnesium alloy is used for the main parts of the limiters and permanent magnets are used to control the magnetic field. Friction and wear of the sealing part for MR fluid can be a problem in such a torque limiter. In this study, an aluminum alloy (A5052) and a magnesium alloy (AZ91) were slid against the O-rings in the MR fluid and its wear and friction properties were investigated.
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Tomoya KADOMAE
Article type: Article
Pages
179-180
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Yoichiro TSUBOI
Article type: Article
Pages
181-182
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Synthetic esters have recently been used as a successful lubricant in MQL(Minimal Quantity Lubrication) machining. However, there is little understanding about the relation between the cutting performance and the lubricating action of these esters. This study surveys esters that are expected to be suitable for MQL machining and investigates the lubricating characteristics of some available esters chosen from the surveyed results. Polyesters show the lower coefficient of friction than that of monoesters. In those polyesters, unsaturated ones show the lower coefficient of friction than that of saturated one. Further, an ester having the higher number of ester bonds in a molecule is found to provide the lower coefficient of friction.
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Isamu Kubo
Article type: Article
Pages
183-184
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A switched reluctance generator (SRG) consists of only iron and copper without permanent magnet material. Therefore, the SRG has feature of robustness because of its simple mechanical structure. It is applicable to the hard environment, high temperature environment and oscillating environment, etc. As its structure is simple, the performance of the SRG greatly depends on the control and drive system. The control system needs high-speed processing as the rotational speed of the SRG becomes higher. This paper describes the performance test using our proto-type SRG control system.
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Takahiro YAMAMOTO
Article type: Article
Pages
185-186
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In pin-on-disk type wear test of silicon nitride ceramics sliding against themselves in water, mirror surfaces were frequently observed under specific sliding condition. On the basis of above results, if flat specimens of silicon nitride slide against themselves in water, it can be considered that we can obtain completely flat and mirror surface without any abrasives and polishing pad. That possibility were elucidated with a flat-on-flat type polishing equipment in this study. Surface roughness of silicon nitride flat specimen that initial surface roughness was 860nmRz decreased with sliding distance and reached to 100 nmRz. A pH value of water increased with sliding distance drastically at initial, decreased gradually with sliding distance and to reached to specific values. On the basis of the analysis of the variation of pH values and polishing amount, the process of tribochemical reaction is considered as the governing process for obtaining flat and mirror surface of silicon nitride.
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Shinya ONOE
Article type: Article
Pages
187-188
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Effects of sliding velocity and normal load on reciprocating wear behavior of SiC particle reinforced aluminum composites (matrix material : 2024Al; particle diameter : 5,20μm; volume fraction of particle (Vf) : 5%, designated as MMCp) were investigated using a reciprocating wear tester. MMCp specimens (plate) were rubbed against bearing steel SUJ2 (pin) at 1-9N and 5-15mm/s. The specific wear rate of MMCp at d=5μm increased with increasing sliding velocity and normal load. On the other hand, at d=20μm did not increase regardless of increasing sliding velocity and normal load. From the analysis of wear data and detailed examination of worn surface and wear debris, wear behavior is different between d=5μm and d=20μm.
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Kenta OHMA
Article type: Article
Pages
189-190
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Regression formulas, which predict the variation of the starvation factor and meniscus distance with the inlet film thickness in starved EHL condition, are obtained by numerical analysis incorporated with Elrod's cavitation algorithm. In order to verify these regression formulas, an interferometric measurement apparatus, which can observe the starved film thickness by successive ball passing, is developed. From observation results by this apparatus, the regression formula for the central and minimum film thickness can fairly predict the variation of the starvation. However regression formulas for the meniscus distances do not agree with observed results. Especially in slightly starved condition, there exists large difference between both.
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Munetoshi IKEGAMI
Article type: Article
Pages
191-192
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In case of a thermal transfer printer, it is important to locate the heater of the thermal print head at the position where the contact pressure is most high. So it is necessary to clear the contact pressure between an ink ribbon and a thermal print head. The visco elastic properties of the ink, PET and platen rubber were measured with a rheometer. The contact pressures on the thermal print head were calculated by FEM. Generalized Maxwell model and three element Maxwell model were used. The calculated results of both models were compared. Moreover, contact regions were examined through the friction experiment of the thermal print head, and they were compared with the calculated results.
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Yasuhiro Murakami, Yoshie Arakawa, Yasuhiro Mogi
Article type: Article
Pages
193-194
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The metal-to-metal friction coefficients of push belt type CVT fluids with block-on-ring, ball-on-plate and element-on-plate tests were compared. Additionally, the effects of detergent-dispersant and anti-wear agents on the friction coefficients with block-on-ring and ball-on-plate tests were evaluated. As the results, it was found the good correlation between block-on-ring and element-on-plate test results. However, it was not found the correlation between block-on-ring and ball-on-plate test results. It seems that the ball-on-plate test results depend on the role of anti-wear agents in the fluid.
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