Method for processing a strand-shaped fiber sliver, and roving frame machine

A method for processing a strand-type fiber bundle, comprising:

• sending the strand-type fiber bundle to an air nozzle of a pre-spinning machine used to produce roving;
• during normal operation, imparting a twist to the strand-type fiber bundle via a vortex air current within the air nozzle to form the roving from the strand-type fiber bundle, wherein the roving leaves the air nozzle through an outlet in the air nozzle;
• from the outlet, depositing the roving in or on a receptacle;
• interrupting the normal operation in a stop phases during which roving is not produced by the air nozzle;
• performing a start-up phase between the stop phase and subsequent normal operation wherein the roving produced during the stop phase is discarded via a roving discharge after leaving the air nozzle when quality of the roving does not meet a desired specification;
• and
• deactivating the roving discharge when the quality of the roving meets the desired specification and separating the roving removed by the roving discharge.