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Wu S.-L.,Chongqing University | Shao Y.-M.,Chongqing University | Yuan Y.-L.,Ningbo Baoxin Stainless Steel Co.
Gongcheng Kexue Xuebao/Chinese Journal of Engineering | Year: 2015

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. © All right reserved. Source

Wu S.,Chongqing University | Shao Y.,Chongqing University | Wang L.,Chongqing University | Yuan Y.,Ningbo Baoxin Stainless Steel Co. | Mechefske C.K.,Queens University
Engineering Failure Analysis | Year: 2015

Chatter marks on the surface of a rolled steel strip may seriously affect the final product quality. It is still difficult to discover the generation mechanism of chatter marks and develop an effective method to identify chatter marks. In this paper a rolling force fluctuation model is proposed based on the variation of the rolling force between the forward and backward skid area. A dynamic model coupling vertical and horizontal vibrations is also established to analyze the vibration characteristics of a Sendzimir twenty-high cold roll mill based on the rolling force fluctuation model. Good agreement between the simulated results and the experimental results verifies the effectiveness of the established models. Furthermore, various rolling forces and rolling speeds are taken into consideration in analyzing the vibration characteristics. The proposed models provide clear theoretical support for better comprehension of the mechanism of chatter mark generation. © 2015 Elsevier Ltd. Source

Li L.,Chongqing University | Wang L.,Chongqing University | Yimin S.,Chongqing University | Yuan Y.,Ningbo Baoxin Stainless Steel Co.
Proceedings of the ASME Design Engineering Technical Conference | Year: 2015

The chatter marks may be caused by the roll misalignment during the grinding process of roll grinder, which can affect the quality of the roll surface of the strip steel. Based on a doubly regenerative time delay grinding model, a 2-degree-of-freedom lumped parameter model of a roll grinder with the roll misalignment fault is presented to investigate the effect of a roll misalignment on its vibration responses. A Runge-Kutta numerical integration method is applied to calculate the vibration response from the presented model. The effects of the roll misalignment and the rolling speed are investigated. Moreover, an experiment setup is presented. Numerical results from the presented model are compared with experimental results to validate the presented model. It seems that the results may provide some guidance for the detection of the misalignment fault and monitoring of the operation state of the roll grinder. Copyright © 2015 by ASME. Source

Shao Y.,Chongqing University | Deng X.,Chongqing University | Yuan Y.,Ningbo Baoxin Stainless Steel Co. | Mechefske C.K.,Queens University | Chen Z.,Chongqing University
Journal of Mechanical Science and Technology | Year: 2014

Detecting chatter mark vibration in rolling mills operating under normal working conditions is difficult. A novel characteristic recognition method of chatter mark vibration, where the non-dimensional parameters are calculated with time varying signals and kurtosis under normal rolling mill operating conditions, is presented in this paper. The character of the chatter mark vibration signal is obtained by calculating the kurtosis value of each vibration signal segment obtained by subdividing the raw time varying vibration signal. The probability density function is utilized to reveal obvious differences between signals with respect to the normal and chatter conditions. The method overcomes the limitation of traditional spectrum analysis, which is sensitive to working conditions. Numerical simulation and experimental results show that the proposed method has better recognition capability than traditional spectrum analysis. © 2014 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg. Source

Liu F.,Zhejiang University of Technology | Liu F.,Zhejiang University | Feng H.,Zhejiang University of Technology | Lu C.,Ningbo Baoxin Stainless Steel Co.
International Journal of Security and its Applications | Year: 2015

In this paper, a novel blind color image watermarking technique using U matrix through QSVD transformation is proposed to protect the intellectual property rights of color images. The proposed method tries to insert the watermark through moderating the coefficient of the quaternion elements in U matrix. .In this method, the color image is considered as an array of pure quaternion numbers. Then the array of pure quaternion is divided into non-overlapping blocks and we perform QSVD to the block to get the U matrix. The watermarking is inserted into the coefficient of the quaternion elements in the first column of the U matrix. Besides, in the procedure of watermark insertion and extraction, ensuring higher fidelity and robustness and resilience to several possible image attacks have been considered. The experimental results showed that the proposed method performance created watermarked images with better PSNRs and more robustness versus several attacks such as Salt &Pepper noise, Brightness adjustment, Sharpen and Blurring and Clipping. © 2015 SERSC. Source

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