Bowed Rollers
Bowed rolls are effective but relatively expensive web spreading devices. A bowed roll is a flexible roll of consistent diameter that is mounted on a central shaft by way of a series of bearings or sleeves along the shaft. When a curvature is induced into the shaft, the result is a bow in the roll face. Bowed rolls remove wrinkles or spread the web because the web will attempt to orient itself at a right angle along the face of the roll, thus pulling each side of the web in different directions. Also, as the web wraps the roll, it has to travel a longer distance at the center and is therefore tighter. Bowed rolls are commonly used to separate two webs just after slitting. Bowed rolls are very aggressive and may cause stretching or distortion in many webs. Furthermore, bowed rollers are very high friction devices and for many web materials, if web driven, may cause more problems than they solve. These rolls often require the installation of separate drive to compensate for their high friction.
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