Expander Rolls

What is an expander roll?

Features of an expander roll

An expander roll refers to a bow-shaped roll for removing wrinkles and shrinkages that are generated in the manufacturing process of sheet products, such as films, paper, non-woven fabrics, and metallic foils.

An expander roll is a bow-shaped roll.

(1) An expander roll consists of multiple spools that incorporate ball bearings on the curved axis. A rubber expander roll refers to an expander roll covered with a rubber sleeve. A steel expander roll refers to an expander roll without such a sleeve.

Wrinkles and shrinkages are removed by stretching a web in the direction of the curved roll.

(2) A web contacts the surface of a rubber sleeve or steel roll that rotates around a stationary axis. The spreading effect produced by the rotation of a curved sleeve or roll to the outward direction removes wrinkles and shrinkages. The front and reverse sides of a base material are not damaged by friction or slippage during traveling.

Correlation between the amount of bow and the amount of spreading of an expander roll

Working principle of an expander roll

	When a sheet travels in contact with an ordinary straight roll with a sufficient wrap angle, it tends to align in the direction perpendicular to the roll axis (Fig. 1).
	This effect remains unchanged even if the straight roll is aslant. That is, the direction in which a sheet travels is always perpendicular to the roll axis. If the roll is aslant, the traveling direction changes (Fig. 2).
	Here, the straight roll is replaced by a KSK expander roll (Fig. 3). The sheet travels straight at the center of the roll. The traveling direction of the sheet changes outward to both sides. Consequently, the sheet is uniformly spread across the entire width. Wrinkles are also removed.