Classical Two-drum Winders

The revdnd station of a classical two-drum winder consists of a first and a second steel drum forming a winding bed wherein the set of rolls is wound side-by-side, and a rider roll. The two-drum winder uses tension, nip load and torque as winding parameters. 

The first parameter tension is necessary to get the single web-sheets spread and to give them a basic strain at the front drum. The amount of tension needs to be in the range of the elasticity of the web. A programmable tension curve is one basic instrument to influence the roll quahty. 

The second parameter, torque , is another tool for controlling the wound-intension or the density of the rolls. Increasing torque tightens the roUs. The torque is introduced by the second drum which is not wrapped by the paper. Therefore the second drum is torque controlled. 

The first drum (wrapped dmm) is a speed controlled drum. 

The third parameter, nip load in the winding bed , results from the weight of the roll set and the rider roll load. At the beginning of the winding process, the weight of the rolls is not sufficient to produce the required Hne load for introducing additional torque by the second drum. Hence it is the rider roll placed on top of 

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The two-drum winder is often called the work-horse among the winders on account of its easy set-up combined with high productivity and efficiency and its initial investment cost being lower than with the single-drum winder. The classical two-drum winder is an economic solution but its technological hmitation is the uncontrollable nip loads that necessarily occur when the roll diameters get above nip-load critical limits, with the consequent risk of roll defects. To overcome this drawback and to achieve low-intensity controlled nip pressures various modifications have been developed. 

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