In this study, dynamic deflections and vibrations of belt conveyors operating in ironworks are observed using a high-speed telephoto mirror-drive active vision that can simultaneously switch viewpoints and capture zooming-in images at hundreds of frames per second. 160-fps video images for a belt conveyor are captured by our active vision system with pan-and-tilt scan as multiple high-frame-rate video images in the experiments, and small deflections and vibrations of multiple belts and pillars, whose peak frequencies are 10 Hz or more, are estimated with the precision of dozens of micrometers by image analysis such as DIC (digital image correlation) when the camera system is 5 m or more away from the conveyor to be monitored.
A sampling moire method is applied to displacement and rotating angle measurement in time series of a practical conveyor belt used in a steel plant in this paper. It is required to develop efficient inspection methods of the healthiness. Authors recently proposed a sampling moire method to measure displacement distribution from a single shot two-dimensional grating image. The sampling moire method is one of the convenient phase analysis methods. The features of the method are high precision, non-contacting, and calibration free. Authors also proposed a rotating angle measurement method using the sampling moire method. Measuring displacement and rotating angle of a part of the structure using a camera in time series for recognizing the dynamic behavior is one of the efficient inspection methods. The purpose of this study is to confirm that the measurement methods of displacement and rotating angle in time series have ability to be applied to inspection of the plant structure healthiness with recognizing the dynamic behavior. In this experiment, displacements and rotating angles at two posts supporting belt rollers are measured using two sampling moire cameras in several conditions. The results suggest that the differences of structure properties can be inspected from measured displacements and rotating angles.
The equipment and the structures in steel works are used in a very long term. Therefore, the inspections and the maintenance are indispensable. To make this more effective, much effort has been devoted to develop methods of fault detection and diagnosis. However, the effectiveness of those methods may be limited due to the tradeoff between false positive and false negative reactions. To mitigate the tradeoff, this paper considers to use model sets involving parameters and disturbances that are expected to change. More specifically, we first propose a method to estimate the parameters and the disturbance so as to minimize the deviation between the real output and the output generated by the model sets. The resulting residual enables us to conduct the health diagnosis. The effectiveness of the proposed framework is examined by using numerical examples.
In this paper, we propose an anomaly detection method for equipment abnormalities using data measured by AreaSensing techniques. The data are gathered from the vibration of equipment installed in a wide area or large scales such as conveyor equipment and bridges. It is difficult to know which data of displacement, velocity, and acceleration is appropriate in advance because each frequency component is different. So, we apply the Hidden Markov Model, which estimates the latent state for each decomposition level by continuously frequency-resolving time series data using Wavelet method. The analysis results show that the normal and abnormally states are estimated. However, as the problem of this method, it is not possible to compare and apply the information criteria such as AIC to the Wavelet decomposed data as it is to appropriately decide which data and model parameters should be used. To overcome the defects, we propose a new evaluation function and developed a method to find a model that can stably estimate the normal and abnormal state transition, even for data separated into different frequencies. Besides, when the current measurement data contains no abnormal state, there was a problem of extracting multiple latent states that are normal but different. We focus on the difference between the state transition probabilities of the normal and unknown model. As the experimental result, the effectiveness of the proposed method has been confirmed. By using the method, it is possible to continuously diagnose abnormalities using vibration measurement data measured by AreaSensing techniques.
In a top-blowing converter, when a distance between the top-blowing lance and the molten metal surface increases, post-combustion ratio increases, but its heat transfer efficiency to the molten metal decreases. Therefore, a fundamental study of behavior of a gas jet from the lance nozzles was carried out in order to develop a new oxygen top-blowing lance with side nozzles with the aim of achieving both higher post-combustion ratio and higher heat supply to the molten metal in converter.
In order to design the shape of the side nozzles and blowing conditions, cold model experiments and numerical calculations were carried out to investigate the effect of the inclination angle of the side nozzles and the flow rate on the gas jet behavior of the nozzles. It was found that the gas jet from the side nozzles was deflected to the direction away from the side wall of the lance due to a difference in the pressure distribution at the nozzle outlet. The deflection angle can be estimated by an equation using the supply pressure, atmospheric pressure and inclination angle of the nozzle.
Abnormally coarse microstructure consisting of coarse pearlite and bainite has been sometimes observed in case hardening steels when they are slowly cooled after hot forging. In order to avoid this abnormal microstructure, it is of industrial importance to clarify its formation mechanism. In the present study, effects of hot deformation condition and cooling rate on the formation of austenite grain coarsening during cooling were investigated by a thermomechanical simulator for JIS SCM420 (0.20C-0.26Si-0.82Mn-1.03Cr-0.15Mo steel, in mass%).
Coarse microstructures were observed when the specimen was deformed slightly at higher temperature after large deformation and subsequently cooled at slow cooling rate. In order to clarify the formation mechanism of coarse austenite grain, strain distribution (GOS: Grain Orientation Spread) in reconstructed austenite orientation map were analyzed for specimens quenched just after deformation. In the condition where coarse austenite formed, the GOS map made it clear that strain was introduced inhomogeneously grain by grain. This result suggested that abnormal austenite grain growth during slow cooling was induced by inhomogeneous strain distribution because growth of recrystallized grains (relatively low dislocation density) into work hardened grains (relatively high dislocation density) was driven by strain energy difference in addition to reduction of grain boundary area.
Machinability of steels containing different carbon contents is evaluated in cutting with a fly tool of TiAlN coated high speed steel, as performed in gear cutting. In order to investigate the effect of carbon content on the cutting process, 0.2, 0.4 and 0.6 mass% C steels are prepared with controlling nearly the same hardness. The cutting tests are conducted to measure the cutting forces, observe the chip formations and analyze the damage on the rake and flank faces of the tools. The machinability of the tested steels is compared each other in terms of the cutting model in the cutting force simulation. The orthogonal cutting data are identified to minimize the discrepancies between the measured and the simulated forces. The shear stress on the shear plane becomes large at high carbon contents, and thus the cutting force increases with the carbon content. On the rake face of the tool, substrate softening and cracking in the coated thin layer occur in a certain cutting length. In cutting of the 0.6 mass% C steel, the cracks initiate rapidly in the coated thin layer on the rake face due to large cutting forces and cutting heat. Small flank wear is observed in the cutting of 0.2 and 0.4 mass% C steels, while in the 0.6 mass% C steel thermal wear with adhesion is promoted at high cutting temperatures.