Analysis and Control of Pouring Ladle with Weir for Sloshing and Volume-Moving Vibration in Pouring Cut-Off Process

Abstract

This paper presents analysis results of molten metal vibration for the pouring ladle of an automatic pouring system and proposes vibration suppression control during backward tilting of the ladle in the pouring cut-off process. The pouring ladle has a weir to avoid contamination of the molten metal. The weir separates the interior of the ladle into a body side and a nozzle side. First, weir effects on flow behavior are analyzed by comparing ladles with and without weirs using computational fluid dynamics simulations. In this analysis, a trapezoidal shaped input is designed as a backward tilting velocity. As a result, molten metal in the ladle with weir shows not only sloshing but also moving-volume vibration at the weir opening area. Secondly, the center points of the tilting motion are each verified by residual vibrations using FFT analysis. The frequencies of vibrating elements are nearly identical; however, analysis results show that the sloshing magnitude varies with changing center point of the tilting motion. In addition, effects of weir position and opening area on peak frequencies are analyzed. Each condition affects a frequency of moving-volume vibration. In addition, weir position changes sloshing frequencies at both body side and nozzle side of the pouring ladle. Finally, the suppression control input for each vibration is designed using the Input Shaping control approach. Design parameters for the control input were identified from residual vibrations, and assumed to be a second-order lag system. The effectiveness of the proposed suppression control input is verified by comparison with the non-controlled case.