Pervious semi-rigid bobbin of molded plastics material for spools of yarn intended for treatments in dye works

Abstract

On its cylindrical wall the bobbin has adjacent longitudinal rows of holes ( 5 ) of substantially rectangular shape with the short sides ( 5 A) orientated circumferentially and the long sides ( 5 B) curving towards the inside of the hole, the holes in one row being offset with respect to those in adjacent longitudinal rows in such a way as to create undulating longitudinal linear structures ( 9 ) between the longitudinal rows of adjacent holes ( 5 ); the curved longitudinal edges of each hole can lie alongside each other in the intermediate zone following uniform radial compressive stressing of the transverse cross-section of the bobbin, while longitudinal shortening of the bobbin is made easier.

What I claim is:  
     
         1 . An injection molded bobbin of plastics material for the formation of spools of yarn wound into turns on it for processing especially in dye works and subsequent unwinding of the yarn, wherein the cylindrical wall of said bobbin has adjacent longitudinal rows of substantially rectangular holes with the short sides orientated circumferentially and long sides curved inwards towards the hole, and having the holes in one row offset with respect to those in adjacent longitudinal rows in such a way as to create undulating longitudinal linear structures between the longitudinal rows of adjacent holes as a result of which the curved longitudinal edges of each hole can lie alongside each other in the intermediate zone following radial compression stress bringing about a substantially uniform reduction in the transverse cross-section of the bobbin, while longitudinal shortening of the bobbin is made easier as a result of the undulation in the said linear structures.  
     
     
         2 . Bobbin according to  claim 1 , wherein the holes in the adjacent rows are offset by approximately half a step.  
     
     
         3 . Bobbin according to  claim 2 , wherein the ends of each bobbin have shapes which are capable of ensuring both mutual centering between axially superimposed bobbins and the formation of a space between the opposite surfaces in order to receive the turns of the stock yarn.