A Bowed Roller consists of number of rolling elements mounted on a curved shaft and is used to sstretch a web (wrinkle removal) or to redirect the path of the web, such as diverging webs after slitting. . It may also be referred to as a “Banana Roll”, “Baloney Roll” or “Spreader Roller”. It is common to have the rolling elements covered by a rubber sleeve.
Bowed Rollers are used for a range of different applications. The main reason for using a Bowed Roller is either to stretch a web (wrinkle removal) or to redirect the path of the web, such as diverging webs after slitting.
The positioning of the Bowed Roller, the amount of wrap and the attitude of the bow relative to the web play an important part if the Roller is to perform well.
How Does a Bowed Roller Work
When a flat web of material passes over a roller the direction of travel is perpendicular to the axis of the roller.
With a Bowed Roller the centre axis is curved, so as the direction of travel of the web is always perpendicular to the axis the roller will stretch the material thus removing wrinkles as shown on the diagram.
Bowed Roller Selection
Size of Roller
Antech Converting produce various sizes of Bowed Rollers to allow the user to select a suitable sized roller for their application.
The table shows our recommended sizes based on the length of shaft and speed.
To calculate the speed of the roller in rpm the following calculation is required:-
Where V is the linear speed in metres per minute (m/min) and D is the diameter of the roller in mm.
|Material||Wrap Angle||% Bow|
|Plastic film||30-90°||1 – 1.25%|
|Metallised film||10-30°||1 – 1.25%|
The wrap angle is the measure of the amount of contact between the Bowed Roller and the web. The amount of wrap angle, although important, does not have to be exact, as it does not effect the spreading action directly. The greater the wrap angle, the greater the force acting on the roller and the web.
Driven Bowed Rollers
Bowed Rollers may be fitted with a pulley that is incorporated into the end cap. The two main reasons for driving the Bowed Roller are when there is a possibility of the web skidding across the roller, due to a combination of low wrap angle and low web tension, or when additional stretching is required.
Antech Converting Bowed Rollers can be supplied with various types of standard rubber coverings including Hypalon, Nitrile & Neoprene and can be offered with special coverings Teflon & Anti-static/Conductive sleeves
Adjuster Gearbox units allow easy change of the bow relative to the web, by turning a handle and positioning the bow. These are are available as either pedestal or flange mounted.
If you require any assistance with your application, our team of experienced Sales Engineers will provide a comprehensive on-site service, to survey the requirements and recommend a suitable solution.
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