In a conventional double twister, a yarn coming from a double twisting spindle ordinarily has a high tension increased by ballooning. Accordingly, a feed roller is arranged between the double twisting spindle and a take-up roller to overfeed the yarn and reduce the yarn tension, and the yarn having a reduced tension is passed through a traverse device and wound on a rotating package by the take-up roller. In forming wound packages by such double twister, especially in case of processed yarns, the tension given by ballooning is not sufficiently reduced by the feed roller and the winding operation is influenced by the yarn tension, with the result that only a hard wound package is obtained. Accordingly, the wound package is unwound and rewound by using a different device in order to form a soft wound package, and the resulting soft wound package is fed to the subsequent dyeing process. Processed yarns of chemical or synthetic fibers tend to elongate even under a small tensile force. For example, when two clerical clips (about 0.6 g) are hung down from the lower end of a processed yarn of the unit length held in the vertical state, the processed yarn elongates and the length is about 1.5 to about 2 times the original length. This is confirmed by a simple experiment. Since processed yarns have such elongation characteristics, a soft wound package cannot be obtained unless the yarn tension on winding is less than 1 g and close to zero.
A high tension is imposed by ballooning on a yarn coming from a double twisting spindle, and it is very difficult to sufficiently reduce this high tension by the above-mentioned conventional feed roller. Even if the angle of winding of the yarn to the feed roller is adjusted, it is impossible to reduce the tension below 1 g. Therefore, according to the conventional technique, it is impossible to obtain a soft wound package in a double twister.