Method and apparatus for the insertion of a weft thread in a weaving machine

Abstract

A method for the insertion of a weft thread ( 2 ) into a shed of an air jet weaving machine ( 1 ) is presented in which the weft thread drawn from the thread store ( 21 ) is accelerated by means of an acceleration nozzle ( 3, 4 ) and supplied to the shed; the weft thread is transported further in the shed by means of a plurality of auxiliary nozzles ( 5.1 a-c to 5. n a-c); and measured values dependent on the speed of the weft thread and/or on the path traveled by the weft thread are measured in contact-free manner by means of one or more measurement pickups ( 7.1, 7.2, 17 ). In the method at least one of the measurement pickups is formed for multiple measurement within the weft insertion and is arranged at or after a first acceleration nozzle ( 3 ). Furthermore, measured values are measured in contact-free manner a plurality of times during the weft insertion by means of the at least one measurement pickup ( 6, 6.1 - 6.5 ) from which values for the speed and/or the path traveled by the weft thread are determined during the weft insertion; and the values determined during the weft insertion are used for the control of the weft insertion.

1 . A method for the insertion of a weft thread ( 2 ) into a shed of an air jet weaving machine ( 1 ) having a thread store ( 21 ), at least one acceleration nozzle ( 3 ,  4 ) and a plurality of auxiliary nozzles ( 5 . 1  a-c to  5 . n  a-c), in which method
 the weft thread ( 2 ) drawn from the thread store ( 21 ) is accelerated by means of an acceleration nozzle ( 3 ,  4 ) and supplied to the shed;   the weft thread is transported further in the shed by means of the auxiliary nozzles ( 5 . 1  a-c to  5 . n  a-c);   measured values dependent on the speed of the weft thread and/or on the path traveled by the weft thread are measured in contact-free manner by means of one or more measurement pickups ( 7 . 1 ,  7 . 2 ,  17 )   characterized in that   at least one of the measurement pickups, which will be termed a special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ) in the following, is formed for multiple or continuous measurement within the weft insertion and is arranged after a thread centering device ( 23 ) provided at the outlet of the thread store ( 21 ), or after the latter or at or after a thread brake ( 9 ) provided separate from the thread store ( 21 ), or at or after a first acceleration nozzle ( 3 ) following the thread store;   during the weft insertion measured values are measured in contact-free manner a plurality of times or continuously by means of the at least one special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ) from which values for the speed of the weft thread and/or the path traveled by the weft thread ( 2 ) and/or for a parameter linked to the speed of the weft thread and/or to the path traveled by the weft thread are determined during the weft insertion; and   the values determined during the weft insertion are used for the regulation and/or control of the weft insertion and in particular for the current weft insertion.   
   
   
       2 . A method in accordance with  claim 1 , wherein measured values dependent on the speed of the weft thread and/or on the path traveled by the weft thread are measured in contact-free manner at least 50 times, or at least 200 times, or at least 500 times within a weft insertion or a part of the same by means of the at least one special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ). 
   
   
       3 . A method in accordance with  claim 1 , wherein, during the weft insertion, or during a part of the same, measured values dependent on the speed of the weft thread and/or on the path traveled by the weft thread are measured in contact-free manner at least every 0.5 ms, or at least every 0.2 ms, or at least 0.05 ms by means of the at least one special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ). 
   
   
       4 . A method in accordance with  claim 1 , wherein the at least one special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ) operates in accordance with a laser interference method, a laser Doppler method or in accordance with a spatial filter method or, together with a second measuring pickup, in accordance with a correlation method. 
   
   
       5 . A method in accordance with  claim 1 , wherein the at least one special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ) is arranged between the thread centering device ( 23 ) and the thread brake ( 9 ), or between the thread brake ( 9 ) and the first acceleration nozzle ( 3 ), or between the first acceleration nozzle ( 3 ) and the end of the shed, or between the first acceleration nozzle ( 3 ) and a second acceleration nozzle ( 4 ), or between the last acceleration nozzle ( 4 ) in the thread insertion direction and the shed, or at the entry to the shed or on a slay or a reed ( 8 ) of the air jet weaving machine ( 1 ). 
   
   
       6 . An apparatus for the insertion of a weft thread ( 2 ) into a shed of an air jet weaving machine ( 1 ), said apparatus ( 20 ) including a thread store ( 21 ), at least one acceleration nozzle ( 3 ,  4 ) in order to accelerate the weft thread drawn from the thread store and to supply it to the shed, a plurality of auxiliary nozzles ( 5 . 1  a-c to  5 . n  a-c) in order to further transport the weft thread in the shed and a measurement pickup or a plurality of measurement pickups ( 7 . 1 ,  7 . 2 ,  17 ) characterized in that at least one of the measurement pickups, termed a special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ) in the following, is formed for the multiple or continuous measurement within the weft insertion and is arranged after a thread centering device ( 23 ) provided at the outlet of the thread store ( 21 ) or after the same, or at or after a thread brake ( 9 ) provided separate from the thread store ( 21 ), or at or after a first acceleration nozzle ( 3 ) following the thread store, in order to measure in contact-free manner measurement values dependent on the speed of the weft thread and/or on the path traveled by the weft thread multiply or continuously during the weft insertion; in that the apparatus additionally has an evaluation part in order to determine values for the speed of the weft thread and/or the path traveled by the weft thread and/or for a parameter linked to the speed of the weft thread and/or for the path traveled by the weft thread during the weft insertion by means of the at least one special measurement pickup, and a control part ( 10 ) in order to regulate and/or control the weft insertion, in particular the current weft insertion by means of the values determined during the weft insertion. 
   
   
       7 . An apparatus in accordance with  claim 6 , wherein the at least one special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ) is suitable for measuring in contact-free manner, measurement values dependent on the speed of the weft thread and/or the path traveled by the weft thread at least 50 times or at least 200 times or at least 500 times within a weft insertion or a part thereof. 
   
   
       8 . An apparatus in accordance with  claim 6 , wherein the at least one special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ) is suitable for measuring, in contact-free manner, measurement values dependent on the speed of the weft thread and/or on the path traveled by the weft thread at least every 0.5 ms or at least every 0.2 ms or at least every 0.05 ms during the weft insertion or a part thereof. 
   
   
       9 . An apparatus in accordance with  claim 6 , wherein the at least one special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ) is a measurement pickup operating in accordance with a laser interference method, laser Doppler method or in accordance with a spatial filter method or a pickup which operates together with a second measurement pickup in accordance with a correlation method. 
   
   
       10 . An apparatus in accordance with  claim 6 , wherein the at least one special measurement pickup ( 6 ,  6 . 1 - 6 . 5 ) is arranged between the thread centering device ( 23 ) and the thread brake ( 9 ), or between the thread brake ( 9 ), and the first acceleration nozzle ( 3 ), or between the first acceleration nozzle ( 3 ) and the end of the shed, or between the first acceleration nozzle ( 3 ) and a second acceleration nozzle ( 4 ), or between the last acceleration nozzle ( 4 ) in the direction of the weft insertion and the shed, or at the entry to the shed, or on a slay or a reed ( 8 ) of the air jet weaving machine ( 1 ). 
   
   
       11 . An air jet weaving machine equipped to carry out a method in accordance with  claim 1 . 
   
   
       12 . An air jet weaving machine comprising an apparatus in accordance with  claim 6 .