Hot-rolling is a metal-forming process occurring above the recrystallization temperature of the material. Many types of hot-rolling processes exist, including structural shape rolling, where a component is passed through rollers to achieve the desired shape and cross section.
Structural steel is the most common hot-rolled material. Common shapes for structural steel include I-beams, H-beams, T-beams, U-beams, and channels. I-beams have an I-shaped cross-section. The horizontal elements of the cross section are called flanges, and the vertical element is called the web.
In this example problem, the hot-rolling process to form the I-beam is simulated statically using rezoning.
The hot-rolling process consists of two primary phases, unsteady and steady. The starting and the ending of the hot-rolling process represent the unsteady phase, while the rest of the process represents the steady-state phase.
In the unsteady phase, the billet (rectangular bar of steel) comes into contact with the rollers and fills the gap between the rollers before moving through the rollers. When the billet begins to move through the rollers, the process is considered to be in a steady state until the end face of the billet comes into contact with the rollers.
Although a transient analysis is often used to simulate the hot-rolling process, a static analysis is generally preferred when dynamic effects are unimportant or when a transient analysis may require excessive resources. This example shows how both the unsteady and steady phases of the hot-rolling process can be simulated via a static analysis.
The static analysis is performed in two load steps: the first builds up the rolling process, and hot-rolling occurs in the second.
In the first load step, the billet moves toward rigid rollers to establish contact with the rollers and to fill the gap between the rollers. In order to build up the rolling process, the billet should partially fill the gap between rollers so that when rollers begin to rotate, they can pull the billet in via friction.
In the second load step, the rollers pull the billet in and eventually shape the rectangular billet into an I-section block.
In this example, the simulation terminates at near the end of the first load step due to mesh distortion. A rezoning operation repairs the distorted mesh, and the analysis resumes and continues to completion using the new mesh.