Online edition:ISSN 2188-0921
Print edition:ISSN 0913-4794

No. 36  NOV. 2018

≪ All Articles ≫
<Feature-Ⅰ>Welding and Joining Technology
1 Flux-cored Wire for HT610 Class Steel Showing Excellent Toughness after PWHT
Dr. Yoshihiko KITAGAWA, Shuji SASAKURA, Masahiro INOMOTO,
Hidenori NAKO, Yoshitomi OKAZAKI 
A detailed study has been conducted to improve notch toughness after post weld heat treatment (PWHT) of weld metal made from flux-cored wires for steel with a tensile strength of 610 MPa class. The microstructure and carbide morphology after PWHT at 620℃ were examined. The results have revealed that the size of cementite particles precipitating along the prior austenite grain boundaries significantly affects the toughness. Presumably, this was caused by the cementite precipitates acting as the initiation sites of grain boundary fracture. To refine the cementite precipitates on grain boundaries, it has been found to be effective to adjust the content of C, as well as that of Cr and/or Mo, carbide forming elements. This study has resulted in a weld metal with an optimal composition for HT610 class steel, the weld metal having an excellent strength after PWHT and toughness at -40℃.
7 Welding Process Using Special Torch for Reducing Diffusible Hydrogen
Naoki MUKAI, Dr. Reiichi SUZUKI 
Diffusible hydrogen is an important factor in cold cracking, and the lower its content, the better. This study contains a discussion and analysis of the behavior of hydrogen sources in metal active gas (MAG) welding consumables (hereinafter, "welding wires") to devise and develop a new process for reducing diffusible hydrogen, a process for suctioning and discharging the hydrogen sources desorbed from welding wires. Evaluation of the effectiveness of the new process has confirmed that it renders harmless the influence of surface lubricant and moisture absorbed after production and is effective as a new technique for reducing hydrogen. The subject welding wires include both solid wires and flux-cored wires (FCW). In the case of the latter, the moisture initially contained in the flux has been significantly reduced for seamed FCW: the effect, however, is less significant for seamless FCW. The present process has been found to be particularly effective when combined with seamed FCW.
17 Robotic Welding System for Shipbuilding
Kenji SADAHIRO, Shuhei HONDA, Shunsuke MIYATA, Yutaku SHO,
As a world-leading welding solution company, Kobe Steel began working on the automation of shipbuilding. A robotic welding system has been developed to be applied to the assembling processes in shipyards. The system includes a robot controller compatible with the small robot that enters hull blocks, a robot carrier for moving within blocks, and robot-program-preparation software allowing offline teaching using 3D models. This paper introduces our robotic welding system offering welding solutions, which integrates all the elements, including the development of optimum welding wires and welding techniques such as gap filling.
23 Features of New Robot Controller, CB-type Controller, for ARCMAN™ Welding System
Takeshi KOIKE, Shuichi INADA, Atsushi FUKUNAGA, Naoki KIDA,
Tsutomu ONE 
Recently, the needs for welding automation have become more diversified and advanced, requiring a robot controller with higher performance and improved functions. Hence, we have developed a new controller, the CB-type controller, which features high performance, highly-sophisticated functions, and ease of use. This paper introduces these three features. In addition, the potential of the CB-type controller is described along with the example of a new arc-sensor control system under development.
28 New Arc-welding Robots
Tatsuji MINATO, Taichi IGARASHI, Motoaki MURAKAMI,
Takashi WADA 
A series of arc-welding robots, the ARCMAN™ series, comes in sizes suitable for various welding objects, and many have been adopted by users in the field of medium and heavy plate. This paper introduces the features of a large-sized robot, ARCMAN™ A80, and a smallsized robot, ARCMAN™ A30, both newly developed. ARCMAN™ A80 is a robot suitable for welding large structures, such as construction machinery, and has enhanced features for improving welding applicability, including an expanded approach area around work pieces, while inheriting the features of the conventional ARCMAN™ XL. ARCMAN™ A30 is a small robot aimed at applications in narrow spaces and features an operating speed and arm shape particularly suitable for the assembly process of shipbuilding.
33 Formation of Fine Microstructure in Weld Metal Containing Mn-Ti based Oxides
Hidenori NAKO, Yoshitomi OKAZAKI, Dr. Hitoshi HATANO,
The formation of fine acicular ferrite microstructure and toughness improvement have been observed in a welding metal in which inclusion particles containing Mn-Ti based oxide are dispersed. The inclusion particles are composed of MnTi2O4 , TiO2 , amorphous and MnS phases, while the acicular ferrite has been nucleated from the MnTi2O4 phase. The Baker-Nutting crystal orientation relationship has been found between MnTi2O4 phase and acicular ferrite, whereas the Kurdjumov-Sachs orientation relationship has been found between the prior austenite phase and acicular ferrite. It has been discovered that the favorable lattice matching at the interface between the prior austenite phase and acicular ferrite may possibly have promoted the nucleation and growth of acicular ferrite, as well as the lattice matching at the MnTi2O4 / acicular ferrite interface.
41 Dissimilar Metal Joining Process "Element Arc Spot Welding"
Liang CHEN, Dr. Reiichi SUZUKI 
Dissimilar metal joining between aluminum and steel has mainly been performed mechanically, however, the method has problems such as production constraints. Hence, we have proposed element arc spot welding (EASW) as a new method for dissimilar metal joining. The new method comprises inserting a hollow steel element (rivet) into a hole in an aluminum upper sheet, after which, the molten filler metal is deposited by arc welding in the hollow part of the element; that is, the element and the lower steel sheet are firmly welded, while the upper aluminum-alloy sheet is tightly held between them. Thanks to the features of the joining mechanism, there is no restriction on the strength of the steel sheet. The method is also applicable to members with closed cross sections. With appropriate elements and welding wires, EASW can assure joint strength equal to or greater than mechanical joining. It allows welding in all positions and tolerates a gap of approximately 1 mm.
<Feature-Ⅱ> Machinery - Industrial Machinery and
              Compressor Technology
50 Tire Uniformity Machine, LIBROTA®
Shinichiro IKAI, Yasuhiro MATSUSHITA 
Tire uniformity machines are used to inspect the quality of automotive tires. Two capabilities are emphasized, i.e., the measurement repeatability expressed by the variation of measurement values when a tire is measured several times and the cycle time for inspecting each tire. There are various restrictions in reconciling these two, and we have reconsidered the structure of mechanical parts, including spindle and drum, and the control component of the machine. As a result, it has become possible to shorten the cycle time to 18 seconds, 10% faster than before, while improving the measurement repeatability to RFVσ≦1.69 N. This paper reports the outline of the technology introduced for improving the measurement repeatability and cycle time performance.
55 Newly Developed Large Size Continuous Mixer (LCM-IM)
Kazuo YAMAGUCHI, Yoshinori KURODA, Toru OKADA 
A new generation continuous mixer has been developed to cope with the advancement of bi-modal high-density polyethylene (HDPE), which is more difficult to mix. Basic mixing experiments were carried out to confirm that the new continuous mixer, which has been developed on the basis of a new mixing theory, effectively eliminates the gels of the bi-modal HDPE film and exhibits mixing performance superior to that of conventional continuous mixers. Furthermore, a new technique for measuring the action force of mixing has been developed. This technique was used to obtain data, which was analyzed by a newly established analysis method to confirm the mechanical reliability of the new continuous mixer.
59 New Technology for Continuous Casting Machine
Tomonori NISHIOKA, Fumiki ASANO, Hiroshi KAWAGUCHI 
In pursuit of high productivity, energy saving, steeltype versatility, and more stringent quality, each engineering company of steel making equipment has made a variety of unique development and improvements of continuous casting machines since its full-scale practical applications in the 1960s. Kobe Steel has newly developed an optimal support mechanism for a large tundish, and a highly precise weighing device for tundish cars, which are closely related to safety and workability. In addition, the company has newly developed a structure, capable of maintaining high rigidity and movements without backlash for an extended period of time, for the mold oscillator and supporting roll stand, which can significantly affect the quality of cast blooms. This paper introduces these technologies, which have been employed in the continuous bloom casting equipment for special steel-equipment that was delivered to Kobe Steel's Kakogawa Works in January 2017.
66 Horizontal CIP Apparatus for Food
High pressure processing (HPP) technology attracted attention in the 1980s as a non-thermal sterilization method, and its research, development and practical application were promoted in Japan. High pressure food processing equipment, which did not spread widely at that time, is now seeing increased demand due to recent situational changes in food companies in Japan. Conventional, vertical, cold-isostatic-pressing (CIP) apparatuses are difficult to install in the facilities of food companies; hence, a horizontal CIP apparatus, "FOOD FRESHER," has been developed. This paper describes the situation in high-pressure food processing technology and outlines the newly-developed FOOD FRESHER and its future development.
72 High-pressure Oil-free Screw Compressor
Kobe Steel's screw compressors for process gas are widely used in the fields of petrochemistry, general chemistry, oil refining, gas businesses, etc., and, more recently, are being used not only in on-land factories, but also in oceanic platforms and offshore applications such as FPSO. In recent applications that require relatively high discharge pressure, such as flare gas recovery and off-shore VRU, for which small compressors have conventionally been used, medium-sized compressors are needed to respond to the users' requirements for an increased gas flow rate. Now, Kobe Steel has lined up medium sized, high-pressure oilfree screw compressors, whose advantages and concepts are introduced in this paper.
77 Large Integrally-geared Centrifugal Compressor
Keiichi SAEKI, Yasuhisa YAMASHIRO, Toshihisa SHIBATA,
Atsushi SANO 
A newly developed centrifugal compressor has a large capacity and incorporates a gear unit. An attempt was made to downsize the compressor, and the cost has been reduced by revising the procurement method of the gear unit, etc. A full load test has been carried out on a prototype machine in the company's proprietary facility to confirm its performance and mechanical stability. As a result of this development, the application range of integrally-geared centrifugal compressors has been doubled, enabling a response to the demands of the expanding market.
81 Vertical Type Reciprocating Compressor for LNG Boil Off Gas (BOG) Injection
Katsuhiro SEYAMA, Satoshi TEZUKA, Takashi OKUNO,
Kenji NAGURA, Naoki AKAMO 
As the shipbuilding industry is enforcing environmental regulations, low-speed dual-fuel engines, such as ME-GI, are attracting rising attention. Such an engine requires a gas-injection compressor (GIC) to supply LNG boil off gas (BOG), and the demand for GICs is expected to grow. Hence, KOBE Steel has developed a vertical type LNG BOG reciprocating compressor suitable for GIC for ME-GI engines. In developing the compressor, we have utilized proven technologies, such as low temperature suction, high pressure discharge, and a high-performance oil-separation system. A vertical type suited to the installation space on a ship has been adopted, and ease of maintenance has been ensured. This paper describes its development.

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