Steel mill main facilities operate at very high working ratio. It is necessary to find the abnormal condition and repair it at the schedule shut down efficiently. This article shows the facility condition monitoring technologies adopted at the steel making and rolling mill area, in the steelworks. The described technologies are hot strip mill condition monitoring, bearing & coupling diagnosis for a large quantity of table rolls using motor current, hydraulic servo diagnosis using data-driven processing, low-speed large-size bearing & reciprocating motion pump diagnosis using high accuracy vibration analysis, online iron powder concentration diagnosis in grease of continuous casting machine.
The rail is an important element for maintaining the safety operation of train. The construction of continuous welded rails (CWR) has been promoted in order to improve riding comfort and reduce the maintenance costs of tracks. However, the CWR has the disadvantage that cracks and defects may occur in the rail including its welds. Therefore, rails including their welds are inspected by a non-destructive inspection method such as ultrasonic flaw detection in order to estimate their soundness. When cracks and defects are detected in rails including their welds, they should be properly treated according to the criteria to prevent failures. This report describes the outline of the nondestructive inspection technology for rails including their welds.
It is indispensable to perform maintenance of bogies of railway vehicles in order to achieve their safety and stable running condition. In current maintenance activities, the bogies are inspected by time-based maintenance. In recent years, however, condition-based maintenance is increasingly being introduced as a means of preventive maintenance of the bogie components such as axle journal rolling bearings and wheels, etc. The article describes an overview of these two condition monitoring techniques with various sensors for the bogie: on-board monitoring techniques and trackside monitoring techniques. The former includes irreversibility temperature indicators on the endcap of axle bearings, axle bearings equipped with temperature sensors and accelerometers, and a bogie condition monitoring with accelerometers. The latter includes wheel flat detections, overheated axle bearing detections, train fire detections and acoustic detections of defective bearings.
Wind turbines are generating clean energy and growing rapidly all over the world, but its maintenance cost becomes sometimes very high when failures or breakages occur at drivetrain subsystems. To avoid unexpected or premature failures, special designs of bearings are required for longer life in severe environment on the wind turbines. On the other hand, CMS (Condition Monitoring System) is also used for effective maintenance work through on-line monitoring of the drivetrain parts.
Remote monitoring technology is utilized for improvement of maintenance for elevators quality and rationalization of work. In this article we will introduce examples of its use and the latest technology. Remote monitoring technology is the most important technique for preventive maintenance of elevators. Inspection contents of machine room-less elevator are seven items such as instruments in the major item and 192 items in the segmented inspection contents. Many remote inspection functions corresponding to these inspection items have been developed. This article introduces two examples. One is an example of door diagnosis, and the second is an example of electromagnetic brake diagnosis. Furthermore, operation measurement data is used for setting the optimum parts replacement cycle and maintenance cycle. Optimization of main rope replacement cycle will be explained as an example of utilization of operation measurement data. As a function other than preventive maintenance, there is a remote rescue function that provides early rescue when passengers are trapped inside the elevator car. Also, it is utilized to prevent damage and to improve the efficiency of restoration work at the time of earthquake. Furthermore, in order to improve the convenience of users, it is used for changing some operation control settings. And, it is also used for information setting of a display device in a car.
The effect of temperature on the lubrication performance of molybdenum dithiocarbamate (MoDTC) was investigated by a ball on disk tribometer with lubricant oil containing MoDTC and calcium sulfonate (CaSU) at temperatures of 25˚C, 40˚C, 60˚C and 80˚C. The behavior of friction coefficient was closely dependent on the oil temperature. Friction coefficient decreased after a certain induction period and became to be constant at a steady state. At higher temperature, the induction period became to be shorter, and the slope of decreasing friction coefficient became to be steeper. Friction coefficient at a steady state decreased at higher temperature, and was changed reversibly when the oil temperature was changed. Oscillatory change in friction was observed when the oil temperature was changed periodically. Chemical analysis of the tribofilm with X-ray Photoelectron Spectroscopy (XPS) revealed that higher content of Mo (IV) as a component of molybdenum disulfide (MoS2) observed in the tribofilm formed at higher temperature. Highly oriented MoS2 layer was observed with High Resolution Transmission Electron Microscopy (HR-TEM) in the tribofilm formed at 80˚C. It was found that the structure of tribofilm is altered reversibly with oil temperature. A steady state model of tribofilm formation was proposed on the basis of observed results.
There has been concern about anisotropic wear properties of UV-LIGA (Ultraviolet-Lithographie, Galvanoformung,Abformung) processed Ni. The depositing direction in the electroplating process, which is one of the UV-LIGA processes,could cause anisotropic crystalline structure. The purpose of this study is to investigate anisotropic wear phenomena of the UV-LIGA processed Ni. The wear mechanism was discussed from the standpoints of crystalline structure based on the wear behavior obtained from sliding tests. Experimental results showed the difference in wear between the horizontal and vertical plane to the plane of depositing. It is considered that the crystalline shape which appeared on the sliding planes affects the wear properties. By the addition of the gloss agent to the electroplating bath, there was significant improvement in the wear property with no anisotropic finer crystalline and higher hardness.
The present study describes the applicability of a bell-mouth geometry to the improvement of the tribological properties of journal bearings of reciprocating compressors for home appliance products such as refrigerators. A roller burnishing process was used to apply a bell-mouth geometry to the edge of cast- iron journal bearings. The resulting geometry of the edge consisted of a micro-scale gradient of 1/1000 and a length of 4-6 mm. The tribological properties were evaluated using a specially-developed testing apparatus, at a constant sliding speed under lubricated conditions. The applied load was increased incrementally in order to evaluate the occurrence of seizure. The specimens were prepared so that they were the same in terms of material, surface roughness, accuracy, and clearance as a shaft and bearing in an actual reciprocating compressor. Significant improvement of anti-seizure properties and a decrease in frictional resistance were found with the bell-mouth bearings. It was therefore concluded that the application of the bell-mouth geometry was effective for improving the tribological properties of journal bearings, and it was found that bell-mouth geometry is also applicable for reciprocating compressors.