設計工学
Online ISSN : 2188-9023
Print ISSN : 0919-2948
ISSN-L : 0919-2948
早期公開論文
早期公開論文の10件中1~10を表示しています
  • 國安 美子, 西坂 強
    論文ID: 2018.2843
    発行日: 2019年
    [早期公開] 公開日: 2019/07/11
    ジャーナル フリー 早期公開

    Grit blasting for surface pretreatment treated before thermal spraying creates enough surface roughness which ensures a strong mechanical bond between coating and substrate. This treatment causes, however, to decrease the fatigue limit of substrate under repeated stress by approximately 3%. In this study, specimens made from JIS SS400 steel were got ready and shot peening and grit blasting were processed (the combined process specimen) for improving fatigue limit. The surface property of the specimens such as residual stress and surface roughness were examined and then the fatigue test of specimens were done. The compressive residual stress generating 30μm below the surface for the combined process specimens was larger than that of the grit blasted ones and roughly equal to that of the shot peened ones. The fatigue limit of the combined process specimens was increased by 9% compared with the grit blasted specimens and by approximately 5% compared with the specimens without any treatments. The experimental results show, therefore, the combined process improves both fatigue strength and macroscopic surface roughness for substrate.

  • Shinya SUZUKI, Noboru WAKAYAMA
    論文ID: 2019.2844
    発行日: 2019年
    [早期公開] 公開日: 2019/07/09
    ジャーナル フリー 早期公開

    This paper discusses the assembly variation that may arise when the positioning between two parts is constrained using a hole and a slot to fit over two locators. This method of controlling mating parts is called “positioning”. Two parts positioned using a hole and a slot fitting over two locators may move relative to each other during assembly because of slight clearances between the locator-hole pair, and/or between the locator-slot pair. The relative motion of two parts using this positioning might simply be considered to be small rotations about the locator-hole joint. However, in many cases, equal locator-hole and locator-slot clearances are toleranced, resulting a motion which is more complex than simple translation or rotation. This paper addresses the motion area that is obtained by positioning using a hole, a slot, and two locators. When the assembly is defined with nominal inter-locator distance of L and locator-hole and locator-slot size clearances of 2δ, the motion area of an arbitrary point (X, Y ) is explicitly described. The motion area corresponding to (X, Y ) is all coordinates (x, y) such that x = 2δ {Y/L(sin θ + 1)+ cos θ }, (tan θ = Y/L), y = 2δ (XL), y = 2δ (2X/L-1) (XL). This paper presents a tolerance analysis application using the above.

  • 坪田 雅大, 本田 知己
    論文ID: 2019.2845
    発行日: 2019年
    [早期公開] 公開日: 2019/07/02
    ジャーナル フリー 早期公開

    For improving automobile fuel efficiency, the internal combustion engines must be required to reduce the friction and wear. Decreasing viscosity of lubricant is effective for it, but the seizure is easy to happen in engines, especially in the plain bearing. Plain bearings of industrial equipment are damaged by the wear, and it is main causes in the failure phenomena. The purpose of this work is to elucidate the wear progression process of plain bearing material in actual sliding environment. The authors have developed new tribometer which can reproduce the sliding condition of actual machines, and carried out wear tests on Al-Sn-Si alloy bearing material. In running-in process, the convex portion of the bearing surface worn out immediately after the start of the test, and a smooth surface was gradually formed. During that process, wear particles containing Fe buried in the plain bearing. Before seizure process, adhesive wear occurred between Al-Sn-Si alloy and S55C immediately after load increase. Thus, microscopic seizure occurred, the friction coefficient and back steel temperature increased, and adhesion area increased. And then, it seems that macroscopic seizure occurs when contact pressure was over the critical pressure. As a result, it was clarified that the wear process under various sliding condition in actual machine can be investigated by the wear tests using the new tribometer.

  • 上代 良文, 木原 茂文, 大塚 滉也
    論文ID: 2019.2846
    発行日: 2019年
    [早期公開] 公開日: 2019/07/02
    ジャーナル フリー 早期公開

    The time-averaged airflow around a mileage competition vehicle was analyzed using computational fluid dynamics in order to optimize the body design to reduce aerodynamic drag and achieve lower fuel consumption. The design parameters were the minimum ground clearance h, the radial clearance of the wheels Sr, and the axial clearance of the wheels Sz. The speeds of the inlet airflow and the ground, relative to the vehicle at rest in the computational domain, were both set to 30 km/h based on the running conditions in the mileage competition. The rotation speed of the wheels was also included in the simulation. The drag exhibits a sharp minimum for a particular minimum ground clearance, hmin, where a remarkable pressure recovery and a decay in the vorticity behind the vehicle body are found. Having optimized the Sr value to achieve a lower drag, the Sz value was then adjusted to keep the steering range of the front wheels. Finally, the pressure drag and friction drag per unit span at the spanwise center were calculated. The pressure drag on the rear body is also found to be minimized at hmin. The validity of the friction drag for the vehicle was confirmed by approximate calculations based on theoretical equations for a turbulent boundary layer above a flat plate.

  • 山田 周歩, 金田 郁可, 山田 哲男, 井上 全人
    論文ID: 2018.2840
    発行日: 2019年
    [早期公開] 公開日: 2019/06/21
    ジャーナル フリー 早期公開

    This paper proposes evaluation method of product module’s adaptabilities of lifecycle options. The purpose of this method based on evaluation index is to provide designer a guideline for designing multi-generational product that belongs Upgradable Product Service System: Up-PSS. Usually, upgradable products are designed under many uncertain design information such as future market trend and procurement cost. This study defines such uncertain information which is used for evaluation perspectives in proposal index as ranged value. In addition, proposal index evaluates module’s adaptability of lifecycle options by using these ranged parameters for adapting such uncertainty. Previously proposed methods evaluate suitability of lifecycle options without a consideration of multiple evaluation perspectives at the same time. Therefore, proposal index comprehensively evaluates component-adaptability of lifecycle options by using multiple evaluation perspectives which are categorized into economic, environmental, reliability, and customer satisfaction aspects. The authors evaluate laptop’s module-adaptabilities of three lifecycle options which are refurbish with upgrade, remanufacturing, and long life by proposal index as a case study. From the result of this evaluation, proposal index enables providing a guideline which is used for the decision-making of providing function and selection of platform components for developing upgradable product service.

  • Keiichi NINOMIYA, Yasunori MATUMOTO, Toshihiko KOGA, Masaki WADA
    論文ID: 2019.2858
    発行日: 2019年
    [早期公開] 公開日: 2019/06/21
    ジャーナル フリー 早期公開

    The purpose of this research is to develop a system that can monitor the condition of the cutting process and keep it always in a normal or optimum state, in which the acoustic emission method is used for monitoring. In realizing the development of such a system, it is fundamental and important to evaluate the source of AE during cutting, that is, the cutting phenomenon qualitatively and quantitatively. In this report, after constructing an experimental system composed of AE measurement, cutting force measurement, and high speed camera, we examine the mechanism of cutting phenomenon from each basic data and discuss the findings obtained from the results. Simultaneously, the correspondence between experimental results and cutting simulation is also evaluated.

  • 長坂 保美, 村田 泰彦, 宮下 良平
    論文ID: 2019.2859
    発行日: 2019年
    [早期公開] 公開日: 2019/06/18
    ジャーナル フリー 早期公開

    The purpose of this study is to establish a manufacturing education system for a large number of novice and experienced students. In the manufacturing process, it is necessary to learn a sequence of basic operations to operate NC machine tools (loading and editing of the NC program, setting of the tools, and running and stopping). However, a large number of students cannot simultaneously learn how to use the NC operating panel because the operating panel is embedded in the NC machine tool. Therefore, we have developed an NC operating panel simulator for learning the above mentioned basic operation in a limited time. We have also developed a practice problem and solving the problem serves to check whether the basic operations of the developed simulator have been correctly learned. This paper describes the development of the NC operating panel simulator and its actual practical use.

  • Kohei NAKASHIMA, Yuito MORI, Hiroshi YAMADA, Masao YOSHIDA
    論文ID: 2019.2856
    発行日: 2019年
    [早期公開] 公開日: 2019/05/31
    ジャーナル フリー 早期公開

    Experimental air-cooled cylinders were produced with slits of various widths cut into their fins. The slits were arranged in an equiangular 30° spiral around the circumference. These finned cylinders were installed in a wind tunnel, with the cylinder axis perpendicular to the air flow, at two different rotations: one oriented so that the center of the fin slit in one row was located directly in front of the air flow, and another rotated 15° around the circumference from that orientation,so no slit was located directly at the front. Heat transfer rate from the cylinder was measured at air velocities between 20 km/h (5.6 m/s) and 60 km/h (16.7 m/s). The air flow between fins was observed using the smoke wire method, and the air flow over the fin surface was observed using the oil film method. Results indicated that, compared with a conventional finned cylinder lacking slits, our finned cylinder with slits increased cylinder cooling. In both slit orientations to the air flow, cylinder cooling increased with increased slit width, up to a point. When the slit width became too wide, cylinder cooling decreased. Furthermore, cylinder cooling increased when the slits were turned away from the air flow, rather than oriented directly in front of the flow.

  • 松本 光広
    論文ID: 2018.2821
    発行日: 2019年
    [早期公開] 公開日: 2019/05/10
    ジャーナル フリー 早期公開

    In the present study, point of application of force, direction of force and severity of force acting on a finger grip in a drawing compasses required for drawing a circle with uniform thickness and dark line on a paper were analyzed. In this paper, as the analytical method, structure and mechanism of the compass were shown, and coordinate system was set in the compass for the analysis. Analytical models based on the set coordinate system were created. There are two cases of ideal force and unideal force acting on the compass in the analytical models. The ideal force acts on the finger grip, and the circle is drawn with the uniform thickness and the dark line on the paper. The unideal force acts on the finger grip,and the circle is drawn with non-uniform thickness and light line on the paper. In analysis results, the experimental tests were conducted about the created analytical models, and the analytical models of appropriateness were checked by comparison between experimental results and analysis results. By use of the analysis results, the impact of drawing the circle with the uniform thickness and the dark line was shown about the point of application of force, the direction of force and the severity of force acting on the finger grip in the compass.

  • 鈴木 真里, 松田 礼, 米村 純一, 町田 信夫
    論文ID: 2018.2842
    発行日: 2019年
    [早期公開] 公開日: 2019/05/10
    ジャーナル フリー 早期公開

    Acoustic vehicle alerting system (AVAS) is a sound that causes pedestrians to recognize the approach of the hybrid and electric vehicles (HEV/EV). The purpose of this study is to investigate the acoustic characteristics of AVAS that satisfy both of the perception that pedestrians can safely avoid against an approaching vehicle and the versatility that can be used even if the listening situation for surrounding sound changes like a smartphone operation during walking. And then, we propose the design guidelines for AVAS based on previously mentioned acoustics characteristics. The AVAS model prototyped in this study is noise with two peak frequencies. We have made the AVAS model with different the peak frequency, the sound pressure level distance, the modulation cycle, and the amplitude modulation factor. The perceptual distance, the distance between the subject and the HEV when the subject recognized the HEV, was measured by bringing the HEV mounting the AVAS model approached from the back of the subject. The listening situation was set four kinds of combination of standing/walking and with/without smartphone operation. We found that effects of sound conditions of AVAS and the difference of the listening situation on the perceptual distance, and shown that the design guidelines for AVAS.

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