Define the type of Rolling of Structural Section Plates and Sheets?
There are two types of Rolling of Structural Section Plates and Sheets.
Flat rolling
- Flat rolling is the most basic form of lamination with the initial and final material having a rectangular cross- section. The material is fed between two rollers, called working rollers, which rotate in opposite directions.
- The space between the two rollers is smaller than the thickness of the starting material, which causes it to deform. The decrease in material thickness causes the material to lengthen.
- The friction at the interface between the material and the rollers causes the material to be pushed. The amount of deformation possible in a single pass is limited by the friction between the rollers; if the thickness change is too large, the rolls simply slip over the material and do not draw it in.
- The final product is a sheet or plate, the first being less than 6 mm thick and the second larger than; however, the heavy plates tend to be formed using a press, which is called forming, rather than rolling.
Foil rolling
- Foil rolling is a specialized type of flat rolling, specifically used to produce foil, which is sheet metal with a thickness less than 200 µm.
- The rolling is done in a cluster mill because the small thickness requires a small diameter rolls.
- To reduce the need for small rolls pack rolling is used, which rolls multiple sheets together to increase the effective starting thickness.
- As the foil sheets come through the rollers, they are trimmed and slitted with circular or razor-like knives. Trimming refers to the edges of the foil, while slitting involves cutting it into several sheets. Aluminum foil is the most commonly produced product via pack rolling. This is evident from the two different surface finishes; the shiny side is on the roll side and the dull side is against the other sheet of foil.
