Online Measurement for Transient Mold Friction Based on the Hydraulic Oscillators of Continuous-Casting Mold
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IN continuous casting, most surface defects of the strand and breakouts originate from and even extend into the mold.[1] Generally, behaviors inside a mold have a critical influence on the formation of an even shell and strand surface quality,[2] while shell quality and breakout are closely related to the heat-transfer and friction force between the newly forming shell and the oscillating mold. High-speed continuous casting results in a lower rate of powder consumption, and thus, more sticking type breakouts occur.[3] A good lubrication between the mold and strand shell is very important for the high productivity of the continuous casting and quality of its product. The lubrication is influenced by the properties of the mold powder but also by the friction forces caused by the periodic movements of mold and the descending strand shell.[4] To ensure the quality of slabs, casting productivity, and the operational reliability of continuous-casting process, it is important to have a satisfactory online control of mold processes. The interaction of the strand shell surface and mold copper plates can be interpreted as mold friction expressed in a physical force, which is one of the most important parameters needed to be measured online in continuous casting, and it can be used to describe XUDONG WANG, Associate Professor, is with the Department of Materials Processing, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, Liaoning, P.R. China, and with the Chief Engineer Office, Jiangsu Shagang Group, Zhangjiagang 215625, Jiangsu, P.R. China. ZHAOFENG WANG, PhD Student, and MAN YAO, Professor, are with the Department of Materials Processing, School of Materials Science and Engineering, Dalian University of Technology. Contact e-mail: [email protected] Manuscript submitted August 27, 2011. Article published online August 7, 2013. METALLURGICAL AND MATERIALS TRANSACTIONS B
strand/mold mechanical interaction and slag film behavior.[5] In addition, monitoring mold friction online also contributes a lot to the evaluation of the powder lubrication, optimization of casting parameters, diagnosis for oscillators, prediction to breakout, and other abnormities.[3,6] Because it provides a quantitative understanding to powder behavior, reflecting operation condition, and quality characteristics, this metallurgical information is valuable to the optimization of casting parameters and prediction to breakout and other abnormalities. Therefore, various research has been published about the online measurement for mold friction.[5,7–11] Few published papers are devoted to research the mold friction under the hydraulic oscillation. In this respect, the method proposed in Reference 12 realized the online measurement of mold friction under hydraulic oscillation, in which the work of mold friction is obtained through the work difference of working forces under casting and no casting. Then, average mold friction in one cycle is computed in considering the amplitude and the mold contact area. Thus, the sy
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