Winding is the creation of large yarn packages that can be easily unwound. This makes using the yarn on subsequent machines both easier and more economical.
In order to form packages of the right weight for subsequent processing stages, the winding machine can be fed by ring-spun yarn bobbins, by packages originating from open-end spinning machines, or by cylindrical/conical packages derived from previous processing stages.
Packages can thus be subdivided according to their shape:
a — cylindrical
b — conical, with tapers ranging from 5° 57° to 9° 15°
c — cones with tapers of up to 4° 20°
The yarn unwound from the package passes through yarn tensioning and control systems, and with the help of a grooved cylinder, is wound evenly around the package; the yarn enters the recess in the cylinder, thus the rotary movement of the cylinder corresponds to the translation of the yarn.
Winding machines currently have independent heads with individually adjustable motors.
A modern winding machine can process yarns ranging from a count of Ne 2 to finer ones, at a winding speed of 400 to 2000 m/min.
Winding is more than just transferring yarn from one package to another. Further functions of winding are to check the yarn and to eliminate any faults found. This is done by a process called .clearing., i.e., by passing the yarn through an electronic device, known as a yarn clearer, which assesses it according to set parameters (fault section and length). If these set values are exceeded the yarn is cut and spliced . a splice being deemed preferable to a fault. Splicing is done using the air-splicing system or the Twinsplicer system, which, reconstructing the yarn mechanically, also checks the untwisting, tail draft, tail condensation and twisting, thereby improving the result of the operation. A join created in this way is less visible, consistent, stronger and repeatable. There exists an innovative combined water- and air-driven splicing system that is particularly suited to compact cotton yarns.
The machine is equipped with a special device to avoid the winding defect known as ribboning. This problem is caused by irregular package formation following the eposition of too many coils in certain points. Basically, the package-holding arm is made to effect an oscillating movement both in the vertical (A) and in the horizontal (B) planes (see Figure 2). These two movements can be combined in various ways so as to respond to all processing requirements.
The tension of the yarn is constantly monitored by an electronic sensor located prior to the cylinder. Thanks to the headstock computer, this sensor interacts with the yarn-tensioning device to modify, as necessary, the tension exerted on the yarn. This keeps the package density constant.
A modern winding machine carries out the following operations automatically;
. package doffing
. bobbin loading
. cone feeding
. linkage to spinning frames with bobbin picking up
For the last of these, the machine can be equipped with a system that allows it to detect two different lots of bobbins and to keep them separate by the application of lot identification tags, which are inserted into the flange and detected upon winding head entry.
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