Modified Two-drum Winders

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. 

This variant of the two-drum winder family consists of a dram and a belt bed to support the roll set As the roll diameter exceeds a certain diameter, the weight of the roll set is partially transferred to the belt bed whereby the specific pressure in the nip is reduced (Fig. 8.6). 

3 Two-drum Winders with Soft Covered Drums 

The purpose of covering the drums with a soft material is to make the nips wider, thus reducing the radial stress between the roUs and the drums to a level where even with heavy rolls no nip load-induced defects can occur. 

The deformation of the covers in the nip especially at the first, i. e. wrapped drum , avoids roll defects such as corrugations and rope marks and allows winding of defect-free roUs with a larger diameter (Fig. 8.7). 

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