The Shell Surface Force Caused by Mould Friction during Slab Continuous Casting

Abstract

In continuous casting, the lubrication and friction between the mould and the initial solidified strand shell play an important role for achieving the high speed casting and producing a good surface quality of the product. Investigation of the frictional behavior is therefore essential for getting a better online control of the mould processes. In the present work, the measurement of shell surface force caused by mould friction was performed during the slab continuous casting. Friction force was calculated to investigate the periodical variations as well as the effect of tensions and pressures on the solidified shell. Also the comparison of the mould friction in sinusoidal and non-sinusoidal mould oscillation was made. This research provided the test foundations and technical supports for studying the mechanical behavior of casting mould and optimizing the casting variables.

Mold Nonsinusoidal Oscillation Mode and Its Effect on Slag Infiltration for Lubrication and Initial Shell Growth during Steel Continuous Casting

“…As previously reported [10][11][12][13], oscillation marks on the strand surface become deeper with longer t n ; hence, the nonsinusoidal mode is favorable in ameliorating the surface quality. The required level of the compressive force imposed on the solidified shell increases with increased relative speed during t n and, due to the elongation of t p , the decreased relative speed in t p between the mold and strand can reduce the tensile force exerted on the solidified shell, which may be critical to solder surface cracking and strand demolding [4]. Several industrial trials and laboratory experiments [6,7,9,10,[14][15][16][17][18][19] have been conducted to investigate the influence of nonsinusoidal oscillation mode on the continuous casting process, as summarized in Table 1.…”

“…Sinusoidal oscillation eliminated the inherent velocity relationship between the mold and the solidifying shell. This technique performed well in healing tiny cracks on the strand surface during the negative strip period (NSP; t n , the portion of the oscillation cycle where the mold descend faster than the shell) [3][4][5] and in the demolding process during the positive strip period (t p , which constitutes the portion of the oscillation cycle where the mold descend faster than the shell) [3][4][5] and in the demolding process during the positive strip period (tp, which constitutes the remainder of the oscillation cycle). With increasing diversity of continuous casting technology, such as use of high-speed casting and some special steel grades, the adjusting ability of sinusoidal oscillation is, however, limited, because it only depends on the oscillation frequency and amplitude.…”

Mold Oscillation Feedforward Control Algorithm for Sinusoidal Oscillation of Various Asymmetries

“…The upward and downward movements of the mold not only reduce the forces that cause the molten steel to adhere to the inner wall of the mold but also promote the dispersion of the mold powder. 1) This oscillation is, therefore, a key element in the continuous casting process as it has a positive effect on the lubrication and friction aspects of the mold flux.…”

“…[1][2][3][4][5][6][7] The oscillation parameters can be divided into three particular parameters: frequency, stroke, and modification ratio. 5) In the steel industry factories, sinusoidal mold oscillation has been used.…”