Hasan Arouni

Grade:  Master

Thesis Title:

Investigation of Forward Slip in Rolling and Its Effect on Rolled Rod Process.

Year: Sept. 2010- Oct. 2013.

Abstract:

Phenomenon of forward slip, during the rod rolling, occurs due to roller velocity and rod. Over forward slip causes elongation and often compaction in rod and along with it; failure in the end product is brought about. In this research, a three-dimension simulation is performed in the No-Twist mill process in rod rolling line of Isfahan steel company by the finite element method. Some achievements of this study include: geometry extraction of rolling line end product, rod velocity during rolling, neutral angle, altitude on neutral plane, forward slip in No-Twist mills. Also, a study on influential parameters on forward slip like coefficient friction impact on forward slip parameter between the roller and the rod, early rod velocity, early rod temperature and the roller rotational velocity on forward slip parameter are carried out. Finally, the stress and temperature distribution during the rod and in rolling path has been studied. In this research, first, to gain the mechanical property of desired steel, standard models of hot tensile experiment and following that to gain different strain rates, a simple tensile experiment took place. Results gained were analyzed using the neural network and the mechanical property of studied steel in different temperatures and strain rates were extracted. By these experiments, it can be derived that as the strain rate increases, the yield point and the ultimate tensile strength point, respectively, increases and decreases, besides, the elastic modulus goes down as the temperature goes up. Next, a visit was paid to the rolling line of Isfahan steel company and the experts and specialists of caliber designers were consulted, also, the first data and experiences of this line were put into use for further validity of researches done. A three-dimension simulation of rod rolling in No-Twist mill process and eventually, an analysis on simulation results, computation of forward slip and other parameters were conducted by finite elements software ABAQUS/Explicit v.6.11. According to the analysis, it can be drawn that as the early rod velocity improves the forward slip parameter fixes for first to third stands. An increase in rotational velocity of the roller for each stand led to a decrease in forward slip. Results gained from the alteration of coefficient friction parameter for each stand demonstrated that increase in coefficient friction between the roller and the rod, in each stage, leads to a growth for forward slip parameter.

Keywords: Forward slip; No-Twist Mills; Hot rolling.