Method and device for preparing randomly cross-wound yarn packages

A method for preparing randomly cross-wound yarn packages at a winding station of a winding machine, comprising:

• (a) winding a yarn onto a package by driving with angular velocity a friction roller in peripheral contact with the package,
• (b) traversing a yarn back and forth along the package with a yarn guide arrangement at a frequency that is directly related to the angular velocity of the friction roller, whereby a winding ratio of the winding process representing the relationship between the number of revolutions of the yarn package for each back and forth traverse of the yarn is defined, and
• (c) when the winding ratio would otherwise be within a predetermined range of a selected whole number corresponding to a pattern zone, alternately
• decreasing the winding ratio to a predetermined value below the predetermined range of the selected whole number by accelerating the friction roller, and
• increasing the winding ratio to a predetermined value above the predetermined range of the selected whole number by decelerating the friction roller,
• said increasing of the winding ratio and said decreasing of the winding ratio each resulting in slippage between the friction roller and the yarn package, and said alternately increasing and decreasing the winding ratio resulting in slippage between the friction roller and the yarn package.

An apparatus for winding randomly cross-wound yarn packages comprising:

• a friction roller for driving a yarn package being wound;
• a traversing guide for traversing of the yarn back and forth alongside the package at a frequency directly related to the angular velocity of the friction roller, whereby a winding ratio of the winding process representing the relationship between the number of revolutions of the yarn package for each back and forth traverse of the yarn is defined, the winding ratio decreasing as the bobbin diameter increases;
• an evaluation device that calculates acceleration values and deceleration values for the friction roller when the winding ratio would otherwise fall within a predetermined range of at least one preselected whole number;
• and
• means actuated by said evaluation device for causing slippage between the friction roller and the yarn package by accelerating and decelerating the driven friction roller whereby the winding ratio is changed between predetermined values above and below the predetermined range of the selected whole number.