Method of operating ring spinning machine during suspension for doffing and method of cutting yarn during doffing

摘要

Disclosed are a method of operating a ring spinning machine during suspension for doffing and a method of cutting yarn during doffing. There is provided a drafting device allowing draft ratio change independently of the driving of a spindle drive system. Prior to forming an oblique winding on cop during suspension for doffing, the draft ratio of the drafting device is changed so as to be larger than the draft ratio of the spinning conducted until then without changing the number of twists to perform the operation during suspension for doffing. By increasing the degree to which the rotating speed of a back bottom roller is reduced, the draft ratio is increased. The number of twists of the yarn forming the oblique winding remains the same while the yarn becomes thinner, so that, when doffing is performed by a doffing device, it is possible to cut the tail yarn at a tail yarn cutting portion so as to attain a short yarn end.