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Published: September 07, 2007
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Article type: Appendix
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Article type: Appendix
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Article type: Index
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A1-A5
Published: September 07, 2007
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Takahiko MURAKAMI, Hiroki ANDO, Naoki MURAMATSU
Article type: Article
Session ID: 2908
Published: September 07, 2007
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This report describes the development of a new soldering iron device with electric tweezers for small parts. It is a tool for a manual rework process to small surface mount devices and mainly composed of a gripping mechanism and a heating mechanism of nipper, We use tweezers using buckling phenomenon as a gripping mechanism because of its excellent performance in gripping millimeter or sub-millimeter size workpieces. And for the heating mechanism of gripper, we use simple heat conduction. By using these mechanisms, it is confirmed that the new soldering iron device can get thin tips and quick heating of tweezers.
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Savaruj Naramonthon, Nobuyuki IWATSUKI, Daisuke MATSUURA
Article type: Article
Session ID: 2909
Published: September 07, 2007
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This paper describes a stabilization control of an in-pipe mobile robot with posture angles information. The four-wheeled platform is synchronously driven by two different motors. Two inclinometers and a gyroscope are attached to the body to collect the posture angles. The position of the robot inside the pipe is estimated by a proposed algorithm. The method requires three posture angles and returns position of the robot, prominently the displacement in the transverse direction, which is later used as an instruction when comes to the control phase. The experiment is carried out in a test pipe of 500mm in diameter and has shown an excellent result in stabilizing the robot to run steadily through the bottom of a straight pipe.
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Tomohiko HASEGAWA, Hidestugu TERADA
Article type: Article
Session ID: 2910
Published: September 07, 2007
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An orthogonal type spherical ball reducer is developed to eliminate the backlash and to realize the miniaturization. This reducer consists of three components which are a grooved cam, a ball follower and rolling balls. The motion principle is analyzed using the polar complex vectors analysis. In addition, the design condition is optimized by the pressure angle and the curvature radius. And this ball reducer is verified using the prototype reducer. It is proved that the efficiency is 47.9%. And the value of a backlash is less than 1 pulse which is the measuring resolution.
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Yohei KAI, Daiki KAMIYA, Mikio HORIE
Article type: Article
Session ID: 2911
Published: September 07, 2007
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A new surface mount system that is composed of a lot of miniature manipulators has been proposed for system down-sizing and high speed. In this paper we propose and evaluate new surface mount system. The surface mount system consists of the surface mount machines to pick-and-place electric devices and the 2-DOF XY table to carry printed circuit board. We considered the way of operation for the surface mount system and evaluated the surface mount system by placement tact simulation program.
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Yohei KAI, Daiki KAMIYA, Mikio HORIE
Article type: Article
Session ID: 2912
Published: September 07, 2007
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A new surface mount system that is composed of a lot of miniature manipulators has been proposed for system down-sizing and high speed. In this paper we developed surface mount system consists of injection pantograph mechanisms made of polypropylene and a positioning XY table, which can operate electric device 0603 (0.6mm×0.3mm). Moreover, we evaluate the system performance. The surface mount system consists of the surface mount machines to pick-and-place electric devices and the 2-DOF XY table to carry a printed circuit board. The surface mount machine consists of the carrying function of injection pantograph mechanism and the function of suction-and-release electric devices by vacuum tweezers attached on the top of the pantograph mechanism. We made surface mount machine, 2-DOF XY table, and circuits to control the system as a trial surface mount system. We evaluated the trial surface mount system about positioning accuracy, velocity of placing, efficiency of placing and so on.
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Kyosuke TODA, Daiki KAMIYA, Mikio HORIE
Article type: Article
Session ID: 2913
Published: September 07, 2007
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In the present paper, a pipe type micro robot made by shape memory polymer is proposed and developed. The shape memory polymer has the big rebound warp limit more than the glass metastasis temperature compared with a general material of almost 100 percent. Moreover, the shape memory polymer can be about 100 times different the degree of elasticity before and behind the glass metastasis temperature, and its structure body become hard more than the glass metastasis temperature, and become rubbery softly below the glass metastasis temperature. By use of this feature, the pipe type micro robot, that is, micro manipulator can bend at the joint by heating actuation. The heating method by use of ultrasonic wave with MHz type is discussed and bending performance at the joint is confirmed in experiments.
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Kazunori MAEDA, Jun NANGO
Article type: Article
Session ID: 2914
Published: September 07, 2007
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In recent years, because the aging society makes rapid progress, the load on the rehabilitation staff becomes a more burden. The help is needed when the patients shift to train walking from using the wheel chair. The walk training make the patient feel pain because they have to support their body with hands or legs when they use the gait training device. The walker which can motivate the patient to train is expected to be developed. In this research, we design and develop the walker with the assist equipment translating the suspected walking motion to the rotating wheel motion. Using this walker, the patients are supported by the saddle, so their hands and legs are relieved from pain keeping their body balance. The assist equipments are designed by using of 6-link or 4-link planar mechanism, which is the oscillating and rotating motion transfer. This mechanism is designed to make its coupler curve simulate the walking motion by means of coupler curve matching.
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Hiroyuki GOTO, Masayuki FUJITSUKA, Yutaka TANAKA
Article type: Article
Session ID: 2915
Published: September 07, 2007
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This paper reports a novel system of multi-axial materials testing system. The proposed system consists of a testing machine, a measuring instrument and a controller. The testing machine is driven by a parallel kinematics (PKM) structure. Making use of the PKM serves not only to achieve complete motions along six axis but also to obtain high dynamical performance. The geometrical relationships of the PKM are derived. We show that the positions of moving platform can be represented as the length of the six limbs of the PKM. The hybrid position/force control scheme derived from a velocity based force control algorithm is introduced, so that we can use velocity-controlled DC servo motors for the PKM. Based on this control scheme, we also propose a method to multi-axial materials testing. The system can be applied to testing on advanced composite materials and components that are difficult to evaluate using conventional testing machines.
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Hideo NAKAGAWA, Yusuke FUKUDA
Article type: Article
Session ID: 2916
Published: September 07, 2007
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On the super-multi joint manipulator that was able to wind and to expand in a three-dimensional space, the amount of the bending error by the self-weight was calculated. Each unit is assumed to be concentrated mass on the middle line of manipulator, and the sum total of the bend moment is obtained. The compliance of the unit to the bending moment was measured by experiment. The load is put on the top of the manipulator, and hand's position and orientation are measured with CMM. The compliance of unit was assumed by the relation between increasing load and the angle to vertical. This bending error can be corrected by addition the presumed bend displacement to reference input of the position and orientation.
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Nobuyuki IWATSUKI
Article type: Article
Session ID: 2917
Published: September 07, 2007
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This paper describes a new method to systematically calculate forward dynamics of spatial closed-loop link mechanisms. Analytical equations to obtain the coefficients of translational and angular accelerations of a moving pair on a crank, two adjacent links with C-S-P pairs, and a coupler link are derived. After solving a system of linear equations with respect to crank accelerations and joint forces and moments, nonlinear differential equations on the mechanism could be solved with a numerical method such as Runge-Kutta method. The calculation program can be easily coded by using some subprogram modules. For an example, forward dynamics of an RSCP spatial 4-bar link mechanism was analyzed in the case where the mechanism started to rotate and the reach to uniform speed of the crank, it was then confirmed that the proposed method was effective and useful.
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Junichi Imoto, Yukio Takeda
Article type: Article
Session ID: 2918
Published: September 07, 2007
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The purpose of this research is a contribution to the mechanism synthesis in a system design by evaluating positioning accuracy of parallel mechanisms after kinematic calibration. In order to realize high positioning accuracy of a mechanism after kinematic calibration, it is necessary to select the optimal measurement condition based on considering the operation performed by the mechanism in the system. So, we developed an evaluation method of the positioning accuracy of a mechanism after kinematic calibration and proposed an estimation index for the positioning accuracy of a mechanism after kinematic calibration. The effectiveness of the method and index was confirmed through simulations.
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Kazuya YAMAGUCHI, Hideo TAKAHASHI, Mikio TAKAHASHI
Article type: Article
Session ID: 2919
Published: September 07, 2007
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The meshing of the crossed helical gears is theoretically considered to be a kind of point contact. The contact brings big power loss and frequent wearing. So, it is used as a motion transmission because of the small load capacity and the low efficiency. However, it may be perform the power transmission, if the contact area of the crossed helical gears increases according to the time passing. However, the contact of crossed cylinders has not tested yet so much. The purpose of the paper is to evaluate the effect of each factor of the scoring strength with the crossed cylinders testing machine. In this study, the operating time was investigated under various conditions of relative sliding velocity and hertzian pressure. The new tendency for the scoring strength was observed by the result of this investigation.
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Yuji Ohue, Yuji Senno
Article type: Article
Session ID: 2920
Published: September 07, 2007
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In order to investigate the influence of fine particle bombarding on the surface fatigue strength of carburized steel under a sliding-rolling contact condition, 2 kinds of bombarded plates were fatigue tested using a thrust bearing testing machine. The same fatigue tests were peiformed also by using as-carburized plate and surface-finished plate by grinding for the comparison. The fatigue test results were discussed statistically by means of non-parametric test and Weibull distribution. The surface roughness of the bombarded plates were almost the same as that of ground plate. From the results of Wilcoxon signed-rank tests, the fatigue life of the bombarded plate with a particle diameter of 50μm was longer than that of as-carburized one under a significance level of 5%. It was clarified from the statistical analysis that the fine particle bombarding process after carburizing causes the longer life for the carburized plate.
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Yuji Mihara, Yoshitaka Ide, Yoshikazu Tateno, Masami Hiraoka, Tsuneo S ...
Article type: Article
Session ID: 2921
Published: September 07, 2007
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In order to measure the contact pressure between gear teeth, we developed a thin-film pressure sensor with thin-straight line type sensing part. The sensor was deposited onto the gear teeth surfaces directly using a sputtering method and the total film thickness was approximately 6.2μm. The design size of a sensing part was designed 10 and 20μm in width and 3 and 5mm in length considering the measurement requirements. The pressure sensing alloy of Cu-Mn-Ni was optimized in order to reduce the temperature sensitivity. As the test result using a torque circulating type test rig, contact pressure was measured successfully indicating maximum value which increased with applied load torque.
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Norio Senbongi, Katsumi INOUE, Tomoya MASUYAMA
Article type: Article
Session ID: 2922
Published: September 07, 2007
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The principal damage of gear is tooth breakage and pitting. The material defect affects both types of damage. A simulation method to estimate the bending strength of carburized gears based on the defect has been proposed. In contrast, the simulation of surface durability has not been presented yet,because the mechanism of pitting is very complicated. In this study, the simulation of bending strength is applied to pitting, and an estimation method of surface durability is proposed. The strength of material used for the criterion of tooth breakage is modified by multiplying by 0.8. The peak-to-peak value of shear stress T*_<yz> is adopted as the measure of proposed simulation. The estimated fatigue limit is close to the test results. The presented method also shows good result in the discussion of the influence of effective case depth.
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Tsutomu NAKANISHI, Daniel Tilahun REDDA, Daisuke Ino, Gang DENG
Article type: Article
Session ID: 2923
Published: September 07, 2007
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In order to improve the surface durability of case-carburized gears, the relationship between temperature of rolling-sliding contact surface and inlet oil temperature under the high load condition was investigated. In this study, a 2-roller type contact fatigue testing machine, test rollers and thermocouples were used. In the roller tests under the condition of various lubricating oil temperatures, the following results are obtained in the rolling-sliding contact surface of the high load condition: First, surface temperature rises remarkably compared with inlet oil temperature. Second, surface temperature reaches the maximum after loading and keeps constant. Third, the influence of risen temperature on the strength of material and the mechanism of lubrication cannot be neglected. Fourth, it is possible to lower the surface temperature by lowering the inlet oil temperature. Therefore, it is thought that the surface durability of case-carburized gears can be improved by controlling the temperature of lubricating oil.
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Hiroshi MORIKAWA, Masahiko NAKAE, Yoshitomo NAKAHARA, Hisashi ABE
Article type: Article
Session ID: 2924
Published: September 07, 2007
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The tooth surface durability of vacuum case-hardened spur gears treated with the double shot-peening was studied. The double shot-peening is consisted of a conventional shot-peening (1st) and a fine particle peening (2nd). The results show that the tooth flanks roughness of vacuum case-hardened gears is about 3.5μmRz and the hardness on a tooth surface is about 950HV after the double shot-peening. Its endurance limit is about 1,900MPa (the maximum Hertzian stress). Although it is close to that without the double shot-peening, it is also about 15% higher than that of gas case-hardened gears.
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Masahiro HIRANO, Kousaku OHNO
Article type: Article
Session ID: 2925
Published: September 07, 2007
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We developed a method for calculating gear temperature that is considered supplying oil quantity on the basis of numerical heat transfer analysis. The purpose was to develop technology that can be used to evaluate scuffing limit of gears. We believe that the gear temperature is determined by the frictional energy that flows into gear tooth surfaces and the energy that flows out of the gear and the gear shaft, and we executed a numerical analysis. Based on experimental measurement and a numerical analysis, the velocity, load and oil quantity changing, the method can be applied, and has an analytical error of less than 5.0℃.
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Hirofumi SENTOKU, Yosuke ASAMI
Article type: Article
Session ID: 2926
Published: September 07, 2007
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Strength of tooth root in flexible spline (FS) in Strain Wave Gearing (SWG) becomes a problem so that FS has a very thin rim. Because teeth in a small-sized SWG are very small, tooth root stress in FS cannot been measured with strain gauges. Therefore, in this study, strain gauges were pasted on tooth root of Circular Spline (CS) which has thickness rim in the large-sized SWG and tooth root stress in CS was measured. Next, influence coefficients of CS between tooth root stress and load on tooth surface were derived. With these result, load distribution on tooth surface was easily calculated. Distribution of tooth root stress in FS was calculated by using FEM.
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Kazuaki ANDO, Kouitsu MIYACHIKA, Takao KOIDE, Satoshi ODA
Article type: Article
Session ID: 2927
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This paper described a study on effects of the case depth, the helix angle and the carburized part on the bending fatigue strength and the bending fatigue crack path of case-carburized helical gears. Bending fatigue tests of case-carburized helical gear pairs of different case depths, helix angles and carburized parts, meshed at the worst loading position where the maximum root stress was considered to occur, were carried out, and S-N curves were obtained. Effects of the case depth, the helix angle and the carburized part on the bending fatigue strength and the bending fatigue crack path of case-carburized helical gears were determined.
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Hiroshi GUNBARA, Kentarou YAJI
Article type: Article
Session ID: 2928
Published: September 07, 2007
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Face gears can be substituted for bevel gears or hypoid gears. They can be used only in restricted applications today. Recently, a new application of face gears for helicopter transmissions has been proposed and face gears have attracted special interest. The geometrical design method for face gear was also clarified. Especially, it was clear how the inner and outer diameters of ring gear are defined. In this paper, for avoiding the influence of machining and assembling error on tooth bearing, the design method of point-contact face gear is described. Concretely, the gear tooth surface is generated by the cutter gear with the same module as and larger number of teeth than the pinion.
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Shigeki MATSUMURA, Haruo HOUJOH
Article type: Article
Session ID: 2929
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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For further, vibration reduction of a gear system, we discuss about availability of active vibration reduction gear system that the pedestals are driven with PZT actuators vertically. For the basis of realization of reliable vibration control system, we discuss about phase and gain relationship between vibration signal on a pedestal and optimal input signal for actuator driver, where mesh component of vibration signal is extracted via band-path filter and input as drive signal changing phase and gain via phase shifter and amplifier.
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Kunihiko MORIKAWA, Ryuta NISHIHARA, Koji KUMAGAI, Masaharu KOMORI
Article type: Article
Session ID: 2930
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The geometrical shape of each tooth flank of mass-produced gears usually varies and is not the same. This variation in the tooth flank shape greatly influences gear vibration and the whining noise of transmissions. The variation may be random or periodical around a gear. The latter type is often found in mass-produced gears such as shaved gears due to the influence of the previous shaving process. The main factors causing periodical variation in the previous process are thought to include gear shaft eccentricity and the inclination of the gear blank. This paper proposes a simulation method for calculating the variation in the tooth flank shape based on these factors. It also describes an improved method of analyzing helical gear transmission error that takes into account the tooth flank shape of every tooth of a gear pair. With these methods, we can accurately analyze the transmission error of a helical gear pair that has variation in each tooth flank shape, by measuring the eccentricity and inclination and without measuring the accuracy of every tooth surface.
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Syuhei KUROKAWA, Yasutsune ARIURA
Article type: Article
Session ID: 2931
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Large waviness in transmission error curves mainly comes from gear radial eccentricity. On the other hand, axial eccentricity, whose parameter value is a half of axial runout, is also regarded as one of the other factors causing waviness components in transmission error. In this paper, transmission error with extremely large amount of axial eccentricity was measured and the influence of axial eccentricity was investigated. From geometrical consideration, it is expected that transmission error with axial eccentricity has two periodic waviness components in one rotation. Measured result showed that transmission error has only one periodic waviness component in one rotation at first sight. However, after applying best-fit identification of radial eccentricity and elimination of pure radial eccentricity components from measured transmission error, two periodic waviness components appeared dramatically. As expected, axial eccentricity doesn't have so great influence on transmission error waviness. Radial eccentricity dominates the waviness components in usual eccentric misalignment.
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Kazuteru NAGAMURA, Kiyotaka IKEJO, Toshiya NAKASHIMA, Eiichirou Tanaka ...
Article type: Article
Session ID: 2932
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Elliptical gear is a mechanism which transmits a non-constant rotation and a power simultaneously. In this study, we investigated on the vibration and noise characteristics of two elliptical gear pairs, which are a single elliptical gear and a double elliptical gear. The circumferential vibration acceleration, the torque variation, and the gear sound pressure level of two elliptical gear pairs and two circular gear pairs with the same number of teeth and the same center distance as the elliptical gear pairs were measured by the running test.
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Shuji HOSOKAWA
Article type: Article
Session ID: 2933
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The necessity for fixation of the bolt head at tightening in the bolt-nut joint is examined experimentally. The relation between the coefficient of friction on fitted portion of threads when it doesn't need to fix the bolt head, and the coefficient of friction on bearing surface of the bolt head is shown. The validity of the relation equation is confirmed by some experiment. It became clear that the bolt head didn't need to fix by the two-step tightening work in the bolt-nut joint.
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Manabu OKADA, shinji KASEI
Article type: Article
Session ID: 2934
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Recently, wheel separation accidents in vehicles such as trucks and buses have drawn a social concern. Explications of their causes and adequate practices of countermeasures for them have been seriously required. In relation to this issue, the authors have taken notice of subjects which are concerned in bolted joints at wheels and are especially trying to study the pressure distribution at the bearing surfaces of nuts. This report deals with this subject about a nut with a spherical bearing surface. Considerations are based on numerical results derived from finite-element-analyses. Feature of the pressure distribution and equivalent stress distributions on bearing surface by this profile are mainly discussed, and concerning this issue some other information is presented.
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Shinji HASHIMURA, Shiho UEMURA, Takuya BABAZONO, Kyoichi KOMATHU
Article type: Article
Session ID: 2935
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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It has been discussed that small configuration errors under a bolt head influence on the variation of frictional coefficient between bearing surfaces in our previous study. In this study, to control the frictional coefficient, which depends on the configuration errors under the bolt, the simulated tightening experiments have been implemented using a lubricant for bolted tightening called Fcon. The results show that Fcon could reduce the variation of frictional coefficient between bearing surfaces in comparison with machine oil VG46.
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Katsumi FUKUDA, Mitsuo KOBAYASHI, Yasuaki OKAMOTO, Hiroyuki CHIKAMATSU
Article type: Article
Session ID: 2936
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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A screw is the machine element being used most closely, and it is being used for the various things, machine and furniture, etc. But, if a screw isn't fastened properly, looseness occurs by the vibration and the shock. It is necessary to control the axial force of screw as a countermeasure in this problem. Such a problem can be solved if the axial force of the small screw can be controlled. However, the research of small screw isn't being done very much. Because of that, the character of small screw isn't appreciated, and such a problem be happening now. This research tried elucidation to the basis character of small screw, to solve a problem about tightening of small screw.
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Shinji KASEI, Takato KOMURA, Satoshi KANAHARA, Jun YAMAZAKI
Article type: Article
Session ID: 2937
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Our previous studies have shown that even under repetition of very small slip at bearing surfaces of bolt nut joints loosening rotation can occur and grow larger. This report presents experimental considerations about external work consumed at bolt-nut joints during repetition of transverse loading and locking performance of a "double-nut" (a nut with a lock nut). The consumed work and its changing state have various patterns in response to properties of test samples. It is considered that its quantity and behavior express features of locking properties of the samples. It is concluded that the locking performance of a double-nut is very doubtful except cases when locking operation is correctly completed.
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Susumu KUMAKURA, Ryo SAKAKIBARA, Akio YAMADA
Article type: Article
Session ID: 2938
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Self-loosening phenomena in bolted joints result in serious accidents. Thus, several types of parts for preventing self-loosening have been applied to important bolted joints in mechanical structures. Recently, the prevailing torque type nuts, in which the friction coefficients are increased at the screw thread and the bearing surfaces of nuts, have been paid a lot of attention and widely used in bolted joints for preventing self-loosening. In this paper, coefficient of friction between threads and bearing surface, and the self-loosening characteristics of bolted joints with the prevailing torque type all-metal hexagon nuts under axial repeated tensile loads were measured.
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Shinji HASHIMURA, Shunsuke INOUE, Tomohiro FURUKAWA, Yoshihiko MORI
Article type: Article
Session ID: 2939
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In this study, self-loosening and fatigue tests of bolt and nut joints subjected to transverse vibrations have been performed to understand the loosening-fatigue characteristics. The current study is especially focused on the influences of lubricant of the bolt-nut joint on the loosening-fatigue characteristics. The result shows that fatigue failure of the bolt-nut joint occures due to propagation of fatigue crack. The result also shows that a lubricant influence on the loosening-fatigue characteristic under transverse vibration.
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Hitoshi Toda
Article type: Article
Session ID: 2940
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Failure analysis is important in the prevention of accidents. But, accident information is not nearly enough to analyze the cause. In this study, we analyze the case of the accident cause for broken wheel bolts. As the results, we confirmed that wear of the loosen wheel bolt is caused by the load at starting the car. But, the load is not concerned the fatigue of the wheel bolts.
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Shinji KASEI, Shinya IWAMOTO, Masaki TAMURA, Takashi OHKUMA, Kiyoto GY ...
Article type: Article
Session ID: 2941
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In strength design of bolted joints, it is important to estimate increase of bolt tensions caused by external loads. "Load factor" is an index expressing how large an additional tension is to an external load. In this report, this index is examined using experimental results, calculated results from the method of the VDI 2230 guideline and calculated results from FEM analyses. It is known that these three kinds of results show similar inclinations, but not always agree well. The values from two kinds of calculations are greater than the experimental values. Additionally, spring constants of bolted joints are discussed as a subject concerned.
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Mitsuo KOBAYASHI, Kanoo Ichinose, Katsumi Fukuda, Michihiko Tanaka, Na ...
Article type: Article
Session ID: 2942
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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According to the current ISO and JIS Standard, in the table of mechanical properties of steel bolts, the impact strength is specified only for the bolts of nominal thread diameter larger and including 16mm. For the steel bolts of nominal thread diameter smaller than 16mm, the impact strength is not specified, because the impact strength test piece of standard dimensions can not be machined from those smaller bolts. This paper reports the results of Charpy impact strength tests using smaller test pieces machined from steel bolts of nominal thread diameter smaller than 16mm, and proposes a test method for impact strength of steel bolts of nominal thread diameter smaller than 16mm.
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Akihiro FURUKAWA, Masaya HAGIWARA, Yohei KAMIYA
Article type: Article
Session ID: 2943
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In ISO/DIS 898-1: 2006, the tensile testing for full-size bolts has been introduced for cold forged bolts, by which the yield strength, the tensile strength and the elongation after fracture can be obtained using load/elongation curve. However, it is difficult to specify the values corresponding to the material property since the mechanical property of cold-forging bolts is not perfectly clarified. This paper aims to clarify the effect of the manufacturing procedures on the tensile property of full-size bolts. The bolts to be tested were manufactured in the same batch and/or the same conditions except the manufacturing sequence, i.e, thread rolling before heat treatment or thread rolling after heat treatment. The results show that the tensile properties for cold-forged bolts can not simulated by the bolts thread-rolled after heat-treated, but by the bolts preloaded, in which higher level of compressive residual stress exists at the thread root.
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Masaya HAGIWARA, Kazunori KAWASAKI, Akihiro FURUKAWA
Article type: Article
Session ID: 2944
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The residual stress at the thread root of a bolt induced by thread rolling is one of the major factors influencing the fatigue strength, and the method (hypothesis) to predict the fatigue strength has been investigated. However, the effect of the residual stress has not been verified quantitatively since there are many other variables affecting the fatigue strength data. This study aims to clarify the hypothesis on the fatigue strength taking into account the effect of residual stress at the thread root. Fatigue tests have been carried out for the heat-treated test specimens after or before thread rolling process. Experimental data show that the fatigue strength of bolts thread-rolled after heat treatment is about 100% higher compared to bolts thread-rolled before heat treatment in the low mean stress condition, and the difference decreases as the increase of mean stress of the fatigue loading. These results show good agreement with the hypothesis presented assuming that the compressive residual stress is 1200N/mm^2 to 1600N/mm^2 level for 8.8 and 12.9 bolts, respectively.
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Eiichirou TANAKA, Tadaaki IKEHARA, Kazuteru NAGAMURA, Kiyotaka IKEJO, ...
Article type: Article
Session ID: 2945
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We developed a power assist mechanism attached to the upper limb, using differential gears. It is being developed for nurses who care an old person being bed ridden, or workers who often lift loads up and down. 2 motors behind shoulder provide motive power to drive shoulder joint and elbow joint, and differential gear makes it possible to divide the power between them effectively. Differential gear system can realize the concentrated drive system, which can reduce the load of shoulder or elbow, comparing to the distinct power motor system attach on each joint. Also, differential gear reduces backlash. We designed the mechanism can assist by 8kg with arms straightened forward horizontally. Experimental result shows the good characteristics following to the angle target.
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Kiyofumi YOSHITANI, Takeshi YAMAMOTO, Akimitsu YAMAMOTO
Article type: Article
Session ID: 2946
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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An analysis was made of the transmission efficiency of a new traction drive transmission incorporating a cam mechanism for automatically generating loading force proportional to the transmitted torque. Driving force in this transmission is transmitted by a power transmission unit, bearings and an Oldham coupling. The transmission efficiency of each element was found from theoretical calculations and measurements of their friction levels in isolation. The measured and calculated efficiencies showed good agreement. The major elements were then assembled into a transmission and its transmission efficiency was measured. High transmission efficiency equal to that of gears was obtained.
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Yuichi NAKAMURA, Fuminori HIRANO
Article type: Article
Session ID: 2947
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Under high contact pressure of traction-type CVT of automobiles, traction oil seems to behave like solid lubricants and elastic contact mechanics (creep theory) seems to be appropriate for evaluation of traction curves similar to that of railway wheels. In the present study, a traction testing machine up to 3GPa was established, in which a sphere and a v-notch-shape roller contacted at two points to generate spin component. Obtained high-pressure traction curves with small spin were lower than the roughly calculated ones based on the creep theory. However, the curves with large spin were almost consistent with them. The modified calculation curves with small spin considering small skew angle 0.2° from pure roll traction experiments, were almost consistent with the above experimental curves. It seems to be impossible to avoid the small skew caused by fitting space of the bearing and eccentric rotation of the coupling even in any traction testers.
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Kiyoshi OKURA, Yasuhiro HASHIMOTO
Article type: Article
Session ID: 2948
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Performance for a frictional power transmission belt such as flat or V-ribbed belts is usually obtained by experiments using two pulleys system for instance and expressed as torque or horsepower of driven axis at the 2% slip ratio. On the other hand few theoretical studies on the performance have been reported. I this paper, a formula to predict the performance of belt systems in which tension is set up by fixed pulley is introduced on the basis of the previous paper which describes relations between initially set up and running state tensions. The formula shows that the performance of a frictional power transmission belt is considerably affected by layout of experiment such as span length and pulley diameter. Then, validities of the formula are verified by experiments.
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Tomoaki OKO, Kazuyoshi NONO, Takuya MORIMOTO, Hiroshi IIZUKA
Article type: Article
Session ID: 2949
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Helical steel cords have been used as an important and convenient machine element for load and displacement transmission. The helical steel cords have been applied as a kind of simple and mechanical remote operation system in various mechanical devices such as automobiles. However, the mechanism of the fatigue failure has not sufficiently been clarified due to the complexity of the fracture phenomenon. It is important to understand the fatigue failure mechanism for the optimum design of the helical steel cords. The purpose of this study is to understand the fatigue failure mechanism of the helical steel cords. Especially, the mechanism of inner bending of the steel cord was discussed observing the core wire that was damaged by the bending fatigue and performing the FEM analysis for the mechanical condition under cord bending.
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Shoji NOGUCHI, Kota NAGASAKI
Article type: Article
Session ID: 2950
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The roller chain is widely used as power transmission element on machines such as motorcycles and transporting machines. In this research, we used FEM analysis to examine the stress distribution of chain when load applied, and analyzed models with weight saving.
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Yusuke TANAKA, Yuichi NAKAMURA
Article type: Article
Session ID: 3001
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Nakamura et. al. had enabled simple measurements of lubricant high-pressure viscosity up to 0.8GPa using a diamond-anvil pressure cell (DAC) by establishing a pressure calibration diagram with a loading screw angle of the DAC. In the present study, the applicability of this method up to 2GPa was investigated by measuring high-pressure viscosity for several alcohols and an ester oil whose viscosity data was reported by Bridgman up to 3GPa. A pressure calibration diagram was constructed, which was proved to be independent of liquids with confirming reproducibility. Employing this pressure calibration diagram, high-pressure viscosities were obtained for some alcohols and they were consistent with Bridgman data up to 2GPa with some data scatters.
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Tatsuya Nagata
Article type: Article
Session ID: 3002
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Very low boundary friction coefficient less than 0.01 appears if a lubricant containing alkyl acid phosphate is employed under low speed and low contacting pressure condition. In order to elucidate the effect of alkyl acid phosphate on this very low friction, microscopic observations of a well-running-in surface by atomic force microscopy are conducted. From the FFM results by a cantilever of which tip is replaced by a glass sphere with 40μm of the diameter, it is found that reaction layers on well-running-in surface, which mainly consist of iron phosphate, has some effect but decisive factor on the low friction in this situation. Since, even in the case of the polished surface, alkyl acid phosphate exhibits a large effect on lower and more stable friction, the low friction may be mainly brought about by thick adsorbed layers of alkyl acid phosphate.
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