Method of producing a staple fiber yarn

Abstract

A method of centrifugally spinning a staple fiber yarn ( 17 ) comprising, in a first stage, drawing a feed material ( 6 ) by a drafting device ( 9 ) into a partially twisted yarn ( 11 ); and delivering the partially twisted yarn into a spinning centrifuge ( 3 ) via an axially shiftable yarn guidance tube ( 7 ); and in a second stage, further twisting the partially twisted yarn ( 11 ) into a finished yarn ( 17 ) while winding it onto a cheese ( 15 ). Before completion of the first stage, a yarn end from the cheese ( 15 ) is placed in the drafting device ( 9 ) onto the feed material and joined to the partially twisted yarn ( 11 ), the feed material ( 6 ) is separated, the yarn direction is changed and the partially twisted yarn ( 11 ) from the centrifuge ( 3 ) is withdrawn in the second stage from the centrifuge ( 3 ) and wound onto the cheese ( 15 ).

What is claimed is:  
     
         1 . A two stage method of centrifugally spinning a staple fiber yarn comprising the steps of: 
 in a first spinning stage: 
 drawing a feed material by a drafting device; and  
 depositing the drafted feed material onto an interior surface of a spinning centrifuge via a yarn guidance tube axially shiftable therein while twisting the drafted feed material between the drafting device and the interior surface of the spinning centrifuge into a partially twisted yarn; and  
   in a second spinning stage: 
 withdrawing the partially twisted yarn from the spinning centrifuge while further twisting of the partially twisted yarn into a fully twisted yarn and winding the fully twisted yarn onto a cheese by a winding device;  
   wherein shortly prior to completion of the first spinning stage: 
 placing a prepared end of a previously finished yarn unwound from the cheese onto the feed material at the drafting device;  
 joining the prepared end of the finished yarn to the partially twisted yarn of the first spinning stage;  
 separating the feed material at the joinder between the prepared end of the finished yarn and the partially twisted yarn;  
 then changing the direction of travel of the partially twisted yarn; and  
 then initiating the second spinning stage by withdrawing the partially twisted yarn from the spinning centrifuge.  
   
     
     
         2 . The method according to  claim 1 , characterized in that the end of the yarn unwound from the cheese is processed in a preparation device before being joined to the partially twisted yarn.  
     
     
         3 . The method according to  claim 2 , characterized in that the end of the yarn unwound from the cheese is at least partially untwisted in the preparation device.  
     
     
         4 . The method according to  claim 2 , characterized in that the end of the yarn unwound from the cheese is thinned in the preparation device.  
     
     
         5 . The method according to  claim 1 , characterized in that the end of the yarn unwound from the cheese is unwound at the end of the second spinning stage at an elevated speed and receives a lesser twist.  
     
     
         6 . The method according to  claim 1 , characterized in that the drawing of the drafting device is briefly elevated during the joining step in the first spinning stage.  
     
     
         7 . The method according to  claim 1 , characterized in that the drawing of the drafting device is briefly elevated at the end of the first spinning stage.  
     
     
         8 . The method according to  claim 1 , characterized in that the direction of transport of the drafting device is reversed to withdraw the partially twisted yarn from the spinning centrifuge.  
     
     
         9 . The method according to  claim 1 , characterized in that a pressure roller of the drafting device is pivoted onto a draw-off roller of the drafting device rotating in the direction of withdrawal to withdraw the partially twisted yarn from the spinning centrifuge.