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No. 31 JAN. 2013
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<Feature-1> Excavators & Cranes
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| 1 |
A Multi-purpose Demolition Machine with Interchangeable Attachments
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Koichiro NIWATA
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A hydraulic excavator operates various actuators and uses them not only for digging, but also for various other jobs. Demolition of buildings is a typical application of an excavator. A variety of attachments have been developed for a wide working range from high to middle elevations as well as for foundations. Conventionally, however, it has been necessary to have an excavator for each specific attachment, and the users had to cover all costs to keep various excavators with different attachments. To solve such a problem, we have developed a series of multi-purpose demolition machines. Each machine has a main boom on which different kinds of attachments can be installed. This article includes descriptions and illustrations explaining the usefulness of the multi-purpose excavators that have been developed.
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The Development of an 8 tonne Class Hybrid Hydraulic Excavator SK80H
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Masayuki KAGOSHIMA
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There is an increasing demand for construction machines with lower fuel consumption to prevent global warming and to decrease the operational cost. In response to such demand, we have developed a hybrid system for an excavator of the 8 tonne class. The system employs advanced power electronic components, such as an electric motor, inverter and battery. These components are similar to the ones that have been used for hybrid cars, but are more sophisticated in that they are designed for an increased number of actions performed by an excavator. When installed in an SK80H model, the system has reduced its fuel consumption by 40% or more and also decreased the noise level significantly.
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| 12 |
Ultra-low Noise Hydraulic Excavators Using a Newly-developed Cooling System (iNDr)
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Hajime NAKASHIMA, Kazuhiro UEDA, Tomoyuki TSUCHIHASHI,
Yasumasa KIMURA, Zenzo YAMAGUCHI
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Reducing noise from construction machinery is important in creating a comfortable environment for residents near construction sites and for operators and workers. This is particularly so because an increasing amount of construction is being carried out in urban areas and at night. This article describes a newly-developed ultraquiet hydraulic excavator that incorporates a patentpending integrated Noise and Dust reduction (iNDr) cooling system. This excavator has achieved a sound power level that is 5dB lower than the most stringent restriction level set by the Japanese Ministry of Land, Infrastructure, Transport and Tourism. The excavator has been launched as one of our general-purpose models.
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| 19 |
Simulation Techniques for Improving the Fuel Efficiency of Hydraulic Excavators
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Dr. Etsujiro IMANISHI, Takao NANJO, Akira TSUTSUI
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Simulation techniques to reduce the fuel consumption in hydraulic excavators are presented in three categories:first, a strongly non-linear dynamic simulation technique for a coupling system with a non-linear hydraulic system and a linkage system; second, a technique for evaluating fuel consumption in the engine when the engine powers the hydraulic pump in a digging operation performed by a hydraulic excavator in real time; and, finally, a dynamic simulation technique for evaluating the efficiency of a hybrid system consisting of power electronics equipment, electric-hydraulic equipment, and a linkage system.
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| 25 |
Reducing Weight and Width of Latticed Boom Crawler Cranes
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Teppei MAEDO, Yasuo ICHIKAWA, Yutaka KOBAYASHI, Eiji MIYA,
Takunori YAMAGUCHI, Hiromitsu HAMAGUCHI
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Reduction of the transportation width to less than 3m and the transportation weight to less than 32 tonnes in Japan (45 tonnes overseas) have been achieved for latticed boom crawler cranes (LBCCs) of the 110 tonne and 250 tonne classes. The lifting weights of the 110 tonne and 250 tonne class cranes are comparable with those of our cranes already on the market. One of the important factors in this achievement is the weight reduction of the boom without sacrificing their lifting capacity. To this end, structural analyses of the booms have been performed using finite-element simulations, and their operational ability has been verified by a newly produced general-purpose LBCC.
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| 30 |
Energy Saving System for Crawler Cranes
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Katsuki YAMAGATA, Takaharu MICHIDA
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KOBELCO CRANES CO., LTD. has developed a new crawler crane equipped with a system for improving fuel consumption and reducing CO2 emissions. The system comprises a fuel-saving mode, a high-speed winching mode, an auto idling-stop mode and the positive control of hydraulic pumps. The new crawler crane has achieved a fuel efficiency that is about 30% better than that of the conventional cranes produced by the company.
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| 35 |
Approach for Improving Fuel Consumption of City Cranes
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Naoto HORI, Joji TERASAKA, Takahiro KOBAYASHI, Naoki SUGANO
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Two control systems have been newly developed for fuel saving in hydraulic wheel cranes: namely, a one-wayclutch system and an advanced engine control system. The former allows one-way transmission of power only in the direction from the motor to the axle and require neither an actuator nor a controller to control the motor action. The advanced engine control system determines the engine rotation speed in response to partial stroke operations of the lever, preventing the unnecessary generation of engine power. It was found that fuel savings of 12% in driving and 20% in crane operation were achieved for the former and the latter systems, respectively, in the practical operation of the cranes.
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| 41 |
Electro-hydraulic Two-Axle Steering System for City Crane
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Koichi SHIMOMURA, Takashi MORITA
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This paper describes a new steering system for a city crane, the RKE450. Unlike conventional fully-hydraulic steering, the new system adapts a mechanical steering system for the front axle and an electro-hydraulic steering system for the rear axles, where the latter system is automatically controlled in accordance with the movement of the front axle. In addition to the safety feature carefully built into the control system, the new steering system also achieves low tire wear, better driving stability, and a smaller turning radius. As a result, the crane complies with the European regulations for driving on public roads at speeds as high as 80km/h and has several auxiliary functions for crane actions in the off-road mode at speeds below 25km/h, as required by the regulations.
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| 47 |
Technology for Evaluating Strength, Stiffness, and Riding Comfort of Crawler Crane Cabins
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Kiyotsuna KUCHIKI, Hideaki HOSOI, Masashi KAWABATA,
Yoshimune MORI
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Evaluation technology based on simulation analyses of the strength, stiffness and riding comfort of cabins has been applied in the development of wheel and lattice boom crawler cranes prior to production. This frontloading evaluation technology was found to be precise and effective in reducing the amount of backtracking necessary to finalize the structure. The technology has been developed in association with the Mechanical Engineering Research Laboratory, Technical Development Group, Kobe Steel, Ltd.
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<Feature-2> Aluminum and Copper Technology
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| 52 |
Nondestructive Measurement of Earing Using an Electro-Magnetic Acoustic Transducer
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Toshihide FUKUI, Yasuhiro WASA, Kazutaka SHIGEOKA
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A highly accurate acoustic velocity measurement system using an Electro-Magnetic Acoustic Transducer (EMAT) has been developed in order to evaluate the texture of aluminum plates. A good correlation between acoustic velocity anisotropy and earing is found for various kinds of aluminum plates, and earing can be estimated to be at 0.5% by measuring the anisotropy of the acoustic velocity. This system is applicable to inline inspection and all-length inspection, and can replace the conventional offline destructive measurement.
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| 58 |
The Combined Effect of Pre-straining and Pre-aging on the Bake-hardening
Behavior of Al-Mg-Si Alloy for Automobile Body Panels
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Dr. Tetsuya MASUDA, Yasuo TAKAKI, Dr. Takeo SAKURAI,
Dr. Shoichi HIROSAWA
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In order to develop a new Al-Mg-Si alloy for automotive body panels, the effect of pre-straining in combination with pre-aging on the bake-hardening behavior of an Al-0.6mass % Mg-1.0mass % Si alloy was investigated by means of the Vickers hardness test, electrical conductivity measurement, differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The hardness test and DSC analysis revealed that, with a pre-aging at 343K, a pre-strain as small as 3% was found to improve the bake-hardening response during final aging at 443K. The TEM observation confirmed that the improvement of the bake-hardening response is enhanced mainly due to the precipitation of the ß" phase in the matrix. These results are explained by the consideration that dislocations induced by prestraining reduce the concentration of quenched-in excess vacancies, resulting in both the suppressed clustering of solute atoms during pre-aging and the accelerated precipitation of the ß" phase during final aging.
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| 63 |
Highly Functional Pre-coated Aluminum Sheets, the "KS700" Series
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Tomoko TANAKA, Nobuo HATTORI
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The KS700 series of newly developed pre-coated aluminum sheets realizes surface functionalization and shortens the manufacturing process. The KS700 series enables the omission of some steps in the manufacturing process, such as degreasing, anodizing and plating, thus saving costs. Products using the KS700 series show good surface qualities and resist fingerprints, scratching and corrosion, among other things. This paper explains the features of the highly functional pre-coated aluminum sheets and introduces several examples of applications.
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| 69 |
The Effect of the Extrusion Temperature on the Recrystallization Textures of an
Extruded AA6005C Alloy
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Dr. Kentaro IHARA, Takahiro SHIKAMA, Keiji MORITA
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A study was conducted to determine the effect of the extrusion temperature on the recrystallized grain size and texture of an AA6005C alloy. Several extrusion tests were conducted at temperatures from 753 to 793K at an extrusion speed of 3m/min. A decrease in extrusion temperature from 793K to 753K was found to increase the average size of recrystallized grains from 170µm to 230µm and the volume fraction of cube-oriented recrystallized grains from 30% to 40%. A hightemperature compression test, conducted to elucidate the process of recrystallized grain formation, revealed that, compared with extrusion at 793K, extrusion at 753K yields fewer recrystallized grains immediately after the deformation, indicating that a larger amount of energy is stored in the un-recrystallized region. The increased stored energy is considered to have promoted the preferential growth of the recrystallized Cube grains.
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| 76 |
A Technology for Manufacturing Magnesium Alloy Components with Excellent Heat Resistance
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Ryoji ASAKAWA, Kenichi HIRUKAWA
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Magnesium alloy forgings have been attracting attention for use in next-generation components with light weight and high heat resistance. A two-step process consisting of casting small diameter rods and forging them offers a viable solution for reducing the cost of forged Mg alloy products. To establish the process, we have developed technologies for continuously casting small diameter rods and for forging Mg alloys with low deformability.
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| 82 |
A New Copper Alloy, CAC5, with Excellent Stress Relaxation Resistance for Automotive Electrical Connectors
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Dr. Koya NOMURA
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Many studies have been made of the Cu-Ni-Sn-P alloy system to develop a copper alloy for automotive electrical connectors because the scraps of the alloys are recyclable in the automotive electronics market. One remaining issue is that of controlling stress relaxation resistance in this alloy system. We have studied the effect of each alloying element on the stress relaxation resistance. The Cu-Ni-P alloy exhibits a higher resistance than either the Cu-Ni alloy or Cu-P alloy. This is probably because pairs that are formed between P and Ni atoms cause a drag force on moving dislocations. Annealing the P containing Cu based alloy for stabilization has improved the stress relaxation resistance. The result indicates that P, segregated at dislocations, decreases the density of mobile dislocations. A suitable combination of these effects enables the copper alloy, CAC5, to be used for automotive connectors even after long exposure to a high temperature environment.
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| 90 |
Dissimilar Metal Joining Technology Using Newly Developed Aluminum Flux-Cored Wire (FCW) to Join Aluminum Alloy and Steel
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Tsuyoshi MATSUMOTO, Tetsu IWASE, Kazumasa KAITOKU, Seiji SASABE,
Masatoshi IWAI, Masao KINEFUCHI
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We have developed a technology for joining dissimilar metals, an aluminum alloy and steel, using MIG and laser welding equipment. A newly developed aluminum flux-cored wire has been found to suppress the formation of brittle intermetallic compound in the bonding interface and to realize a joint strength that compares with the strength obtained by a similar joint of the aluminum alloy. The corrosion resistance of the welds was evaluated. The butt joint was found not to exhibit any electrolytic corrosion. This technology was used to build prototype car structure members to evaluate their strength and the applicability of the technology.
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| 96 |
A Basic Study of Dynamic Recrystallization in Cu-Sn-P Alloy for High Strength Copper
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Dr. Masato WATANABE, Akihiko ISHIBASHI, Dr. Hiromi MIURA
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Dynamic recrystallization (DRX) behavior in a newly developed Cu-Sn-P alloy was systematically investigated. Hot compression tests were performed on alloy samples having different crystalline conditions, i.e., as-cast coarse-grained polycrystalline and orientation-controlled bicrystals. Also tested were Cu-Sn-P alloys with varying Sn content. As a result of Sn addition, the Cu-Sn-P alloy was found to undergo DRX that is much delayed compared with that of a conventional Cu-P alloy. The delayed DRX is considered to have increased the flow stress and strain required for processing the Cu-Sn-P alloy. When compressed under conditions that are close to the conditions of the actual operation, the alloy was found to exhibit a significantly inhomogeneous microstructure. This structure seemed to be refined and homogenized as a result of static recrystallization during the subsequent cooling period after extrusion. It is concluded that the DRX in Cu-Sn-P alloy is dominated by discontinuous type DRX governed by the annealing twins formed behind the migrating grain boundaries.
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