Conventional Method

The conventional design is most commonly used when running multiple tube and pipe sizes made of mild steel with a T/D ratio (thickness divided by diameter) between 3-8%.  If the gauge thickness is below 3% or above 8%, other styles of design are recommended, such as Edgeform, Versatile Edgeform, or W-Style.  The single-radius design is very forgiving during setup since it is not as critical that it be centered like the other breakdown styles.

A taller side roll profile may be needed when using this design, in order for the tube to be properly shaped to enter the fin passes. This is important in order to avoid overworking the strip and inducing instability.

The conventional style is a single-radius design and is only used when specified by the customer or if existing sets on the mill run conventional design since most demand more range of gauges and material types on one set.  It has several limitations:

• Other design methods, such as edgeform and “W-style” allow easier setup to design and chart figures
• The top roll center areas only completely form the strip to the bottom radius in the working area of the roll, leaving the earlier pass radius in the strip edges
• The side roll radii will not fill out correctly, due to the rest of the strip edge radii being flatter, having been formed in the earlier passes

Even with its limitations, the conventional style is commonly used in many applications and provides a good quality product where it can be used.