Study on hot rolling process of the D51 large-diameter threaded bars

다국어 초록 (Multilingual Abstract)

The objective of this study is to design a hot rolling process for manufacturing large-diameter threaded bars. Threaded bars in which longitudinal ribs are eliminated and transverse ribs play a role as a screw thread can be used as rebars. To design the hot rolling process for the D51 threaded bar, the mean reduction and rolling pass numbers were determined. Calibers (box, oval and round caliber) were designed using the bar rolling theory. Six cases of the peanut caliber were designed by changing the main design parameters, namely caliber width (W) and center groove (R1), to analyze the shape of the threaded bar with respect to the shape of the peanut caliber. Furthermore, the rolling pass schedule including the average effective roll diameter (AERD) and rolling velocity was set. FE-simulation and artificial neural network (ANN) techniques were used to derive a combination of design parameter for the peanut caliber and rolling process of the D51 threaded bar. The rolling experiment was conducted using peanut caliber and rolling process derived by FEsimulation and ANN technique. After measuring cross-sectional area of the core part and transverse rib, the unfilled rate (U.R) of the core and transverse rib were compared and analyzed. The height of the transverse rib and cross-sectional area of the D51 threaded bar formed by rolling experiment was satisfied with the allowance tolerance of ±4 %. These results verified the reliability of the hot rolling process of the D51 threaded bar.

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