Abstract: The relationship between the size distribution of inclusions and the total oxygen in steel was studied by following the inclusions' size and number of the samples at different locations. The content of macro-inclusions in liquid steel could be estimated accurately by the fluctuation of total oxygen in the same sample,which quantified the cleanliness evaluation index. The number of inclusions per unit volume decreased exponentially with the increase in sizes. Also,the distribution uniformity of inclusions in steel worsened as the size increased. Thus,micro-inclusions with the size below 10 μm occupied above 95% of total inclusions in the liquid steel,which showed a good relationship between the measured value of total oxygen and the integration oxygen in micro-inclusions.Total oxygen could represent the uniform distribution level of inclusions in steel; good uniform of inclusions in steel meant small fluctuation. Macro-inclusions could result in the fluctuation of total oxygen. Large fluctuation of total oxygen reflected a high amount of macro-inclusions in steel.
Abstract: A cubic flatness pattern expressed by Legendre orthogonal polynomial was introduced to build a new flatness pattern recognition model,in which least squares regression was used. Using the new model,flatness pattern recognitions of 2180 mm CVC ultra-wide cold rolling mill and 1550 mm UCM common wide tandem cold rolling mill were carried out. The results show that the main flatness error of the strip produced by the ultra-wide mill is "OS cubic waves" considering the cubic flatness pattern,and "quarter waves" without the cubic pattern; the main flatness error of the strip produced by the common wide mill is "central waves" whether considering the cubic flatness pattern or not,therefore the necessity of introducing cubic flatness pattern for the new recognition model is verified. Finally,potential application of the new model in the asymmetric flatness control of ultra-wide tandem cold rolling mill is discussed.
Abstract: A new method for the evaluation of stress in cold rolled strip based on magnetoelastic effect is presented. The sensor output characteristics were studied and its magnetic stress detection principle was also described. Using the ANSYS finite element method,simulation analysis of the structure carrying capacity of the calibration device model was conducted. Choosing a 50 Hz sinusoidal AC excitation system,a magnetic elastic stress measurement system prototype with the gap of 1.5 mm was developed. A performance testing platform was built to characterize the sensor output test of the prototype. The testing results show that the device can achieve linear response for stress in the steel sheet and provide a new way for the wide application of the magnetic elastic stress measurement technology.
Abstract: Multi-line lasers were applied to the on-line defect detection for steel rails instead of single-line laser,which solved the problem of "pseudo defects" due to the vibration of rails under the mode of single-line laser. Images of multi-line lasers captured by camera were processed to realize the online detection and the accurate defect feature area was acquired with steps of the extraction of strip centers,detection of difference algorithm,discrimination between real and pseudo defects,image mosaic,etc. Images of the defect area were extracted by the cross-correlation and self-correlation information of laser curves,and there was no need for the step of depth mapping under the single-line mode,so the problem of "fault detection" caused by the vibration of rails was solved fundamentally. The technique is applied to on-line detection of defects for the bottom side of steel rails,and the detection rate is much higher than manual detection.
Abstract: Stretchable electronics are mainly composed of the organic substrate and the metal thin conductor attached to the substrate. The geometric parameters of both substrate and metal conductor play an important role in the flexibility of stretchable electronics. In this paper,the effect of geometric parameters(length,width,and thickness of the substrate) on the flexibility of stretchable electronics was studied. The ABAQUS software was used to simulate the uniaxial tensile tests on the polyimide-supported copper conductor to determine the effects of geometric parameters of the substrate on its flexibility. As shown in the results,the effect of substrate length on the deformation of the system is very small; while the increase of width or thickness of the substrate can decrease the substrate deformation but increase the strain of metal conductor. This work can provide a theoretical support for the geometrical design of stretchable electronics.
Abstract: For the shortcomings,such as low efficiency of jet energy and poor uniformity of water and abrasive in the post-mixed abrasive water jet descaling nozzle,three kinds of structures of the nozzle were put forward:the side feed nozzle,the tangential feed nozzle,and the parallel multi-jet nozzle. Based on the CFD Eulerian multiphase flow model,the 3-dimensional numerical simulation of the three kinds of structures was conducted with the FLUENT software. And the acting mechanism of the high-pressure water with the abrasive was analyzed through the velocity vector of the flow field inside the nozzle. The uniformity of the flow field was compared by analyzing the volume fraction contours of abrasive. Results show that compared with the side feed nozzle,the tangential feed nozzle and the parallel multi-jet nozzle can improve the mixing effect and obtain a rather uniform abrasive distribution. Whereas,the tangential feed nozzle can augment the internal wear of the nozzle,which needs a kind of more wear-resistant material. Compared with the former two structures,the mixing effect of the parallel multi-jet nozzle is perfect and the water jet flow as well as the acting mode could be adjusted according to the need in practical application.
Abstract: The total oxygen content(T. O),non-metallic inclusions and the relationship between them in pipeline steel,gear steel,tire cord steel and Q235 steel,which were taken from industrial products,were systematically investigated by ASPEX automatic scanning electron microscope(SEM),which can scan large area metallographic specimen,and thermodynamic software Thermo-Calc was used to calculate and validate. The obtained results indicate that non-metallic inclusions are greatly influenced by the production process of steel. With the inclusion size increasing,the amount of inclusions in this size range decreases. Both quantity and area of inclusions increase sharply when T. O increases from less than 0.002% to 0.01%. When T. O is lower than 0.002%,it only shows good positive relationship with the area of all inclusions per square mm steel samples. T. O indicates the area of inclusions in steel more accurately than the quantity of inclusions. Large sized inclusions appear accidentally. The experimental results agree very well with thermodynamic calculations and the content of T. O,[S] in steel.
Abstract: The quality problem of head width narrow appears on one hot rolled strip line sometime. In order to using the real data,in this paper the dynamic time warping was firstly utilized to transfer the different length data to the same length,and then the feature selection method based on information entropy was applied to analyze the order of important about process parameters that effect on the quality. The first several process parameters were selected as the causes of head width narrow of hot rolled strip. The results show that the feature selection method based on information entropy can track the causes of the head width narrow of hot rolled strip effectively to adjust the process. In the future,the methods can be applied in other quality diagnosis,other processes or other application fields.
Abstract: Texture of the surface and center of the cold-rolled low-carbon steel sheets were measured by X-ray diffraction method.The experimental results show that {112} 〈110〉 and {001} 〈110〉 texture components exist in the surface of the steel sheets and {112} 〈110〉 and {111} 〈110〉 texture components exist in the center of the steel sheets. It is obvious that the cold-rolled textures of the low-carbon steel sheets are inhomogeneous from surface to center. The textures evolution process of body centered cubic metals were simulated by the modified Sachs model and the simulation results show good consistence with the experimental results.
Abstract: The hot rolling of strip is a multi-stage production process. There are about a hundred of control parameters and target parameters which are related to the quality of products directly in the multi-channel processes. It is the main development orientation for both the literal research and engineering practice to improve the quality of hot rolling products,by finding the information between the control parameters and target parameters,and making use of the information. It is investigated that combining data mining with the industrial features of hot rolling productions,the potentially,useful,ultimately understandable process knowledge can be extracted.The correspondence relationship between quality defects and control state can be got. Through a comprehensive analysis of control parameters weight vector and the set of high-risk relationships,the key control parameters can be find to improve. This method can reduce the economic losses,improve the production efficiency,and provide the scientific and accurate idea for the quality analysis of hot rolling strip production.
Abstract: Periodic impulses in vibration signals and its repeating frequency are the key factors for diagnosing rolling element bearing faults. A new method based on ensemble empirical mode decomposition(EEMD) and cross energy operator was proposed to extract the characteristic frequency of bearing fault. Firstly,the signal was decomposed into intrinsic mode function(IMF) by means of EEMD to satisfy the mono-component requirement by the cross energy operator. Next,the sensitive IMF was selected according to correlation and kurtosis,and instantaneous cross energy between the IMF and the original signal and its Fourier spectrum were calculated. Finally,the bearing faults were diagnosed by matching the repeating frequency of fault-induced periodic impulses with the fault characteristic frequency. By analyzing both a simulated faulty bearing vibration signal and the experimental data of bearing faults,the bearing faults were diagnosed and the effectiveness of the proposed method was validated.
Abstract: Aiming at fault diagnosis of inner race,outer race and rolling element of ball bearing,a fusion method based on ensemble empirical mode decomposition(EEMD),morphological spectrum,and support vector machine(SVM) was proposed. Firstly,the vibration signal was decomposed by EEMD to get several intrinsic mode functions(IMFs) which have physical meanings. Secondly,the IMF which was rich in fault features was selected as the data source based on power maximum of IMFs. Thirdly,morphological spectrums in some scales of the IMF were extracted,and then they were adopted as the fault eigenvectors. Lastly,the three faults of ball bearing faults were diagnosed by the use of SVM. The conclusion is that the proposed method can diagnosis the faults of the ball bearing with high accuracy.
Abstract: In the grinding process of roll grinder,chatter marks are easily to be found on the surface of the roller,which is harmful to the production efficiency and quality. There may be lots of reasons to chatter marks,among which grinding wheel dynamic imbalance was chosen to structure the roll grinder dynamic model based on doubly regenerative time delay grinding model. Runge-kutta algorithm was used to solve the model and the dynamic characteristics of grinding wheel dynamic system were derived. Various simulation results of different degrees of grinding wheel dynamic imbalance are calculated,which coincides with the experimental data,and then the roll grinder dynamic model was demonstrated to be proper and valid.
Abstract: The fluctuation of rolling speed and the torsion variation of the main drive shaft are inevitable in the rolling process,which leads to the rolling skid between the roll and the strip. The skid will significantly influence the surface quality of the strip. The dynamic rolling skid model was established for the drive system of Sendzimir twenty-high roll mill. The characters of torsion vibration were analyzed based on the different rolling speeds and friction coefficients. The simulated results were agreement with the experiment results,which not only validates the effectiveness of the established model,but also provides a new model for analyzing the fluctuation of the torque.
Abstract: Basing on the Volume of Fluid(VOF) model of Computational Fluid Dynamics(CFD),the 3-D numerical simulation of the idling furnish roll in the producing process for color-coated sheet was performed with the FLUENT software. And the effects of some parameters on the uniformity of coatings were analyzed,such as the rotation speed of furnish roll,the amount of lacquer in the plate,the size of lacquer plate,the inlet and outlet locations of lacquer plate and the inlet velocity of the lacquer. For producing the color-coated sheets,numerical results show that the uniformity of coatings becomes worse as the rotation speed of the furnish roll increases; the higher the lacquer height in the plate is,the easier it emerges foams; the uniformity of coatings becomes better as the length and width of lacquer plate increase; the ability of producing the foams becomes stronger as the inlet velocity increases; the inlet and outlet locations of lacquer plate also influence the uniformity of coatings.
Abstract: Using on-line monitoring equipment for coupled vibration of tandem mill,the signal of drive shaft torque and rolling force were obtained. Regression analysis shows that the neutral angle oscillates at the same frequency in deformation zone. The variation rule of the neutral angle was deduced by using rolling theoretical formula when coupling vibration happens. Then the increment equations for variation of neutral angle caused by rolling vibration were established,and the influencing rules of the variation of deformation zone parameters on the neutral angle were obtained. The results show that effective control of deformation zone parameters can enhance the stability of neutral angle and thus suppress rolling mill vibration.
Abstract: The flattening machine made the aluminum strip perform repeatedly stretch bending deformation before cold rolling process. The flattening process has a vital influence on strip rolling process by improving plate shape and residual stress distribution of the strip in the same time. In this paper,the flattening process was researched by finite element method software Abaqus according to a five roll flattening machine. In order to describe behaviors and principles of the flattening process,a series of new definitions and descriptions were put forward. Based on numbers of simulation of different kinds of shape defects and systemic analysis,relations between the effect of flattening and different degrees of plastic deformation were discussed. The results show that the best flatness parameter is decided by the shape of itself.
Abstract: One kind of detection and prediction method for abnormal grid voltage has been designed due to the case that modern power electronic equipment is sensitive to non-stationary time-varying voltage signal. This method sends the network voltage abnormal warning signal to control-circuits of modern equipment through detecting the grid voltage in time. To eliminate the conventional noise jamming of the voltage signal,this scheme adopts linear tracking differentiator to filter the signal. On this basis,wavelet transform modulus maxima are proposed in singularity detection,so as to accurately forecast abnormal harm points in power electronic devices caused by the grid voltage. Simulation and experimental results show that the wavelet analysis based on linear tracking differentiator can obtain the best approximation of the ideal signal and provide more useful forecasting signals for power electronics equipment,thus the fault detection speed and efficiency are improved significantly.
Abstract: From the view of the mill main driving control system,instability model of the electromechanical system and control strategy were researched. In the premise of ensuring the steady and dynamic performance of the control system,the model of main drive of two inertial systems was simplified,the inside and outside disturbance of the system was observed by linear extended state observer. By linear feedback and dynamic error feedback method,the detection and control of electromechanical system failure were achieved. The closed loop controller design method based on simplified differential equation model was proposed,and validated by simulation and experiment. The results show that this study has a significant effect on solving the instability caused by load changes of rolling mill system.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
