Method For Monitoring a Yarn Transforming Process

Abstract

At least one yarn is unspooled from at least one bobbin using a spindle cap. The unspooling speed and, in a coordinated manner, other parameters associated with the transformation process, are adjusted according to a quantity representative of the amount of yarn remaining wound on the at least one bobbin, so that the unspooling speed remains below limits imposed by unspooling conditions.

1 . Method for monitoring a yarn transforming process in which at least one yarn is unspooled from at least one feed bobbin using a spindle cap mounted rotating freely while being driven by said at least one yarn, in which variation in quantity of yarn remaining wound on the at least one feed bobbin or a diameter of said at least one feed bobbin gives rise to unspooling conditions which affect equality or performance of the transforming process, wherein unspooling speed and, in a coordinated manner, other parameters associated with the transforming process, are adjusted according to a quantity representative of an amount of yarn remaining wound on the at least one bobbin, so that the unspooling speed remains below limits imposed by the unspooling conditions. 
   
   
       2 . Method according to  claim 1 , wherein the representative quantity is obtained by a direct or indirect measurement of the diameter of the at least one feed bobbin. 
   
   
       3 . Method according to  claim 1 , wherein the representative quantity is obtained by a direct or indirect measurement of weight of the at least one feed bobbin. 
   
   
       4 . Method according to  claim 1 , wherein the representative quantity is obtained by a direct or indirect measurement of speed of rotation of the yarn around a periphery of the at least one feed bobbin, or of the spindle cap which rotates at a same time as the yarn. 
   
   
       5 . Method according to  claim 1 , wherein the representative quantity is determined from a value initialized at a start of the unspooling, and decremented as a function of time according to a pre-programmed law, or as a function of a representative quantity of a variation in said quantity. 
   
   
       6 . Method according to  claim 1 , wherein the representative quantity is determined from a value initialized at the start of the unspooling, and decremented as a function of measurement and/or computation of amount of yarn unspooled, or as a function of a representative quantity of the unspooling speed. 
   
   
       7 . Use of the method according to  claim 1 , for a method of single twist, double twist, stranding, or covering of yarns in which the at least one yarn is unspooled from the at least one bobbin using the spindle cap mounted rotating freely while being driven by the yarn and using at least one spindle, wherein:
 speed of rotation of the spindle and speed of traction of the yarn are controlled by one or more independent means, in a constant ratio, in order to give the yarn a constant twist per metre;   the speed of rotation of the spindle and hence proportionally the speed of traction is adjusted as a function of a quantity representative of the amount of yarn remaining wound on the at least one feed bobbin.   
   
   
       8 . Use of the method according to  claim 1 , for a method of single twist, double twist, stranding, or covering of yarns in which the at least one yarn is unspooled from the at least one feed bobbin using a spindle cap mounted rotating freely while being driven by the yarn and using at least one spindle, wherein speed of rotation of the spindle and speeds of delivery members of the yarn are controlled by one or more motorizations independent of adjacent positions, while adjusting the speed of rotation of the spindle and the speeds of said delivery members as a function of a quantity representative of the amount of yarn remaining wound on the feed bobbin in a variable ratio, thereby conferring on the yarn a variable twist per metre, in order to compensate for variations in twist per metre caused by the unspooling as a function of said diameter. 
   
   
       9 . Use of the method according to  claim 1 , for a method of single twist, double twist, stranding, or covering of yarns in which the at least one yarn is unspooled from the at least one bobbin using a spindle cap mounted rotating freely while being driven by the yarn and using at least one spindle, wherein:
 speed of rotation of the spindle and speed of delivery members of the yarn are controlled by one or more means independent of adjacent positions, in a constant ratio between the speed of the spindle and the delivery members, in order to give the yarn a constant twist per meter;   the speed of rotation of the spindle and hence proportionally speed of traction is adjusted as a function of a quantity representative of the amount of yarn remaining wound on the feed bobbin;   the speed of rotation of pre-delivery means is adjusted to slacken the yarn from the spindle to compensate for variations in tension in a balloon due to the variations in speed of the spindle and thereby to restore a constant spooling tension.   
   
   
       10 . Use of the method according to  claim 7 , wherein speed is controlled in accordance with a law of variation of the speed of rotation of the spindle and proportionally the speed of traction as a function of the amount of yarn remaining wound on the feed bobbin, the law comprising a substantially constant zone between an initial amount of a full bobbin and an intermediate amount, and a substantially decreasing zone between the intermediate amount and a minimum amount or zero at an end of unspooling. 
   
   
       11 . Device for implementing the method according to  claim 1 , wherein each working position is equipped with members controlled by independent motorizations, so that the transforming process parameters can be adjusted as a function of a quantity representative of an amount of yarn remaining wound on at least one bobbin in the working position, independently of status of adjacent working positions. 
   
   
       12 . Device according to  claim 11 , wherein monitoring of a spindle and of delivery members having individual motorizations is controlled by speed variators, each variator receiving a speed setpoint from a computation unit. 
   
   
       13 . Device according to  claim 12 , wherein data representative of the amount of yarn remaining wound on the bobbin is communicated to the computation unit which modifies each speed setpoint according to laws of variation as a function of the said diameter. 
   
   
       14 . Device according to  claim 11 , wherein preparation of the quantity representative of the amount of yarn remaining wound on the bobbin, and/or computation of production speed and its transmission to member monitoring means are provided by a computer or an electronic circuit, or a programmable logic controller. 
   
   
       15 . Method for monitoring a transformation process by single twist, double twist or stranding of yarns in which at least one yarn is unspooled from at least one feed bobbin and using at least one spindle,
 wherein speed of rotation of the spindle and speed of traction of the yarn are controlled by one or more motorizations independent of adjacent positions, by adjusting the speed of rotation of the spindle and speeds of yarn delivery members as a function of a quantity representative of an amount of yarn remaining on the feed bobbin in a variable ratio, thereby conferring on the yarn a variable twist per meter, and of a law of variation as a function of the quantity representative of the amount of yarn remaining on the feed bobbing, in order to compensate for variations in twist per metre caused by unspooling or respooling operations of twisting process or upstream or downstream transformation processes.   
   
   
       16 . Device according to  claim 12 , wherein the computation unit comprises an electronic card or a programmable logic controller.