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

No. 37  Apr. 2019

≪ All Articles ≫
<Feature-Ⅰ>Excavators & Cranes
1 Electric Motor HILS System Using Numerical Stabilization Technique for Simulating Nonlinear Coupled System
This paper introduces a stabilization technique of nonlinear coupled analysis for hydraulic excavators, in which a rigid body system and a hydraulic system are coupled. Also introduced is a "Hardware-In-the-Loop Simulation (HILS)" for electric motors, in which the above technique is exploited. The rigid body system consists of a rotating element and a linear motion element, and the stabilization technique converts the motion of the rotating element into linear motion, enabling the motion of both the systems to be described in an ordinary differential equation without introducing any constraint conditions for the rigid bodies. This enables a coupled analysis with one motion equation that shares the state quantities of both the systems, thus improving the stability of the numerical analysis. This technique has been used to simulate in realtime the actual load acting on the electric motor, which has been reproduced on a motor-load testing apparatus and has realized an electric motor HILS system.
8 Duct Shape Design Technology Based on Evolutionary Algorithm Considering Noise Attenuation Performance and Air Permeability
Satoshi TABUCHI 
This paper relates to a technique for designing the engine room of a hydraulic excavator equipped with an Integrated Noise & Dust Reduction (iNDr) cooling system. In order to improve the noise attenuation performance, changes in cross-sectional area and bends have been introduced into the muffler duct of the iNDr structure. On the other hand, changes in cross-sectional area and bending will deteriorate the air permeability and decrease the cooling capacity. Thus, in a muffler duct, the air permeability of the cooling air and noise attenuation performance are in a trade-off relationship. Against this backdrop, an optimum design technology has been developed using a multi-objective genetic algorithm (MOGA) to achieve both air permeability and noise attenuation performance in the intake duct of the iNDr structure of the engine room. This technology has enabled the design of an engine-room shape taking both the air permeability and noise attenuation performance into account.
15 Loss Analysis of Electric Motors in Hybrid Excavator
Yoichiro YAMAZAKI, Seiji SAEKI, Dr. Kazushige KOIWAI 
Kobelco Construction Machinery Co., Ltd. has launched a new 20 tonne hybrid excavator, equipped with two types of newly developed electric motors, namely, a permanent magnet type, flat, high-torque generator motor, and a compact high-output slewing motor. In an electric motor, iron loss and copper loss occur, and these losses increase as the internal temperature rises. Therefore, the challenge in making compact electric motors with high torque and high output is to release the heat generated inside the motors to the outside and to prevent their internal temperature from rising. A technique has been established for the coupled analysis of an electrical/magnetic circuit model and a heat transfer circuit model in an electric motor that enables an optimal design of the heat transfer path inside the motor, as well as making it possible to efficiently find an appropriate electromagnetic circuit for it. This has resulted in the development of electric motors with high torque density.
21 Disturbance Rejection Filter for Depth Sensor
Masashi HAMAGUCHI, Dr. Takashi HIEKATA 
In recent years, data obtained from sensors attached to excavators are being widely used in assisting the operators. The processing unit logic of such a sensor system has been developed to ensure flexibility in the design of the sensor system. As a part of this development, an effort has been made to solve the problem of detecting disturbances, such as rain, snow, and insects, when the depth sensor is used for outdoor measurements. An object placed in front of a depth sensor in a raining environment was moved back and forth while continuously measuring the appearance of the object. In the measured data, points with possible disturbances were chosen. The speed, direction, and acceleration between frames were calculated as feature quantities, which led to the development of a disturbance rejection filter that eliminates the points above set thresholds. This filter has been confirmed to detect the position of objects while ignoring the influence of rain in real applications.
25 Development of 20-tonne Class Hybrid Excavator, SK200H-10
Yoichiro YAMAZAKI, Seiji SAIKI, Nobuhiro KOGA, Akira TSUTSUI,
Kazuhide SEKIYAMA, Kengo MAEDA 
Power electronics technology continues to evolve, particularly in the automobile industry, with the aim of reducing fuel consumption and the environmental burden. This technology was adapted for a hybrid hydraulic excavator, the SK200H-10, equipped with a lithiumion battery, as introduced in this paper. A continuous engine assist has been realized for the hydraulic excavator by effectively using the regenerative energy generated during slewing deceleration, due to the large inertia of its slewing body, and by adopting a lithiumion battery with high output and large capacity. As a result, the fuel consumption of the excavator has been reduced significantly. The scrap handling machine (with magnet), the SK210DLC-10, has the same generator motor as SK200H-10 and applies a hydraulic excavator with a totally new power generation system, which was formerly based on a hydraulic pump. This machine enjoys a remarkably increased magnetic attraction and considerably reduced fuel consumption, thanks to the reduced energy loss during power conversion.
31 Evolution and Development of iNDr
Kazuhiro UEDA, Tomoyuki TSUCHIHASHI, Hajime NAKASHIMA,
Integrated Noise & Dust Reduction (iNDr) is an advanced proprietary cooling system with the two unique functions of noise reduction and dust removal. It is installed in an ultra-low-noise hydraulic excavator launched for the first time in 2007. With its extremely low noise and dust-proof performance, it is used preferentially at many sites. Rather than becoming obsolete, it has gained in popularity, thanks to its performance. Environmental regulations are becoming increasingly stringent, and the constraints on equipment have become increasingly severe in connection with the development of smaller models: for example, the addition of a new function, mixing cooling exhaust and engine exhaust, is now required. Due to these circumstances, design tools based on fundamental theories, which allow more efficient study, are being utilized to evolve the iNDr into a "crossover duct" with a new structure, while maintaining its extremely low-noise performance.
<Feature-Ⅱ> Utilization of ICT
36 Development of New Production Scheduling and Manufacturing Logistics System for Takasago Machinery Plant
Rihito IZUTSU, Toyohiro UMEDA, Hideo IKEDA, Yukihiro ONISHI,
For the machinery plant of the make-to-order (MTO) type Machinery Center in the Takasago Works of Kobe Steel, a system for scheduling and logistics management has been developed to improve the product assortment rate, an index for the rate of on-time delivery to the subsequent assembly plant. For scheduling, a method was devised for estimating excessive overloading to support the determination of the amount to be outsourced. For the logistics, a mechanism was established to collect progress data and the locations of parts with RFIDs, the information necessary for preparing schedules. The introduction of this system has improved the assortment rate by approximately 20% compared with the value normalized by the average assortment rate before the introduction of the system.
41 Method for Predicting Gas Channeling in Blast Furnace
Kazufumi KAMO, Kazuhisa HAMAMOTO, Dr. Hiroshi NARAZAKI,
Dr. Tomoyuki MAEDA, Masahiro YAKEYA, Yosuke TANAKA 
In order to maintain stable operation of a blast furnace, deviations from the steady state should be quickly detected and corrected. Because internal physical states are difficult to measure directly, experienced operators play a crucial role in integrating information from various sources such as sensors and visual observations so as to recognize, predict, and react to probable anomalies. Overlooking undesirable symptoms or delayed actions possibly leads to the excessive loss of heat, which, in the worst case, can cause the abnormal shutdown of operation. One of the events highly associated with the risk of heat loss is gas channeling, which sets off an alarm signaling to the operator to decrease the flow rate of input hot gas. Gas channeling is judged to be imminent by the integration of indices designed so as to detect unusual changes in the variations and patterns of sensory data. The precision of our prediction method is evaluated by using actual data.
48 Collision Warning System for Locomotives Carrying Molten Pig-iron in Kakogawa Works
Dr. Toshiharu IWATANI, Hiroshi KATSURA, Masahiro TAMURA 
This paper describes a collision alert system for locomotives that carry molten pig iron in the Kakogawa Works of Kobe Steel. This system comprises a process computer that stores the positional information, determined by the GPS, of locomotives along with their railroad track information in order to generate warnings. The railroad tracks laid in the steel works are more complicated than those of railroad companies and may cause various types of collisions. Hence, the railroad tracks are represented in a computer on the basis of graph theory to establish an algorithm for predicting collisions accurately and quickly. The newly developed system has been utilized continuously, promoting the safety of the locomotive operation.
56 Development of Prediction Technique for Temperature Distribution of Molten Steel in Steelmaking
Dr. Nobuyuki TOMOCHIKA, Dr. Takehiro NAKAOKA,
Takehiro TSUKUDA, Yoshiyuki NAGASE, Hiroshi KATSURA,
Kazuki SUMIDA 
To promote the transfer to younger workers through operation support, a technique has been developed to present, in a probability distribution, the deviation risk for molten steel temperature in the converter furnace, molten steel treatment, and continuous casting steps involved in processing. This technique constructs a probability distribution by converting and transferring massive amounts of recorded data concerning past performance into information corresponding to the current operational state. It is based on a physical model, weighing the information in accordance with the degree of similarity. Its advantages are that calculable factors are separated from uncertain factors in a deterministic manner, the time change of the uncertain factors is taken into account on the basis of thermal influence, and Just-In-Time modeling is applied, which enables the systematic calculation of the probability distribution even for different conditions of such factors as steel types and facilities. This technique has been applied to an actual steelmaking process, which has reduced the deviation of casting temperature from the target value to less than half of the conventional one.
63 Development of Macro Simulation Model to Support Multi-product, Mixed Flow Production of Aluminum Rolling
Toyohiro UMEDA, Akihisa HORIO, Satoru YOSHINO,
Katsumasa UEDA 
The manufacturing processes for the sheets, plates, and strips of steel, aluminum, and copper that are Kobe Steel's main material products are characterized by the mixed production of a great variety of products. Hence, for the sake of productivity and quality, a plurality of workpieces processed by an identical type of method are aggregated together as one lot on the basis of the operating conditions specific to each apparatus. A simulation model has been developed to support production planning and to help in considering operational rules as well as the capital investment policy involved in such processes. The model has a hierarchical queue structure to flexibly express various lot-making operations. The model further incorporates a mechanism for estimating the time it takes before the minimum number of workpieces required to organize a lot become available in order to reduce the unwanted stagnation of jobs in the process. The effectiveness of the proposed model has been demonstrated by numerical experiments, while its accuracy and applicability in the macro evaluation of material flow have been verified using actual plant data on aluminum rolling.
72 Applications of ICT to Robot Welding System
Takeshi KOIKE, Yoshihide INOUE, Atsushi FUKUNAGA 
In recent years there has been a rise in expectations for the improvement of the productivity of robot welding systems using information and communication technology (ICT). To meet these customer needs, Kobe Steel has developed a 3D-CAD link system that retrieves the data of workpieces from the design department and automatically detects welding lines to create a robot program. This has eliminated the need for customers to teach robots and has greatly improved their productivity. The company also provides a production monitoring software, called AP-SUPPORTTM. This software has the capability of automatically collecting production data for the welding robot system and outputting reports on production results, thus contributing to the improvement of productivity at customers' sites.
77 Development of Image Sensing Technology for Automatic Welding (Image Recognition by Deep Learning)
Tsuyoshi ASHIDA, Akira OKAMOTO, Keita OZAKI, Masatoshi HIDA,
Dr. Takayoshi YAMASHITA 
A system has been developed for automatic MAG welding with ceramic backing. This system comprises a camera to capture the images of the molten pool for recognizing feature points to control the torch. A regression-based deep convolutional neural network (DCNN), which outputs continuous values from image inputs, was used to recognize feature points such as arc center and the leading end of the molten pool. This has enabled the accurate recognition of the distance from the arc center to the leading end of the molten pool, as well as the width of the molten pool, with an average error of 0.44 mm or less. The formation of a proper back bead has been confirmed in a welding experiment on a test piece with a tapered gap (from 3 to 10 mm).

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