Fabric Club Of BD: Feb 27, 2011

WINDING-1

Labels: Weaving Manufacturing Technology | at 2/27/2011 10:02:00 PM

Winding:

Winding is one of the most important operation, which is mainly occurred in spinning section. Besides, it is also important in fabric manufacturing. In fabric manufacturing, directly winding is not so much important, but rewinding is so important.

The creation of large yarn packages that can be easily unwound, is called winding. This makes using the yarn on subsequent machines both easier and more economical.

After warping, some packages contain just a few grams of yarn which is unsuitable for the efficiency of further processing, such as warping, twisting, and quelling. This necessitates the preparation of a dense and uniform yarn package of sufficiently large size from unsuitable packages which can unwind in the subsequent operations without interruptions, is called rewinding.

The yarn unwound from the package passes through yarn tensioned 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.

Fig: Winding head

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.

Materials Processed:

Input - Yam (spinning bobbins)

Output - Yarn (large cones, tubes, etc.)

Objectives of the Process:

Ø Inspect the yarn

Ø Clearing of defects

Ø Lubricate the yarn

Ø Package the yarn

A basic diagram of winding m/c:

Fig: yarn winding

Elements of Winding:

1. Yarn withdrawal

2. Yarn tensioner

3. Yarn clearing

4. Stop motion

5. Take up

Fig: Open wind cone.

Importance of winding:

Unevenness in traditionally spun staple yarns is a natural phenomenon usually induced by the process of manufacturing (spinning). Although with modern process controls and machines many imperfections in the spun yarns can be controlled, some still remain in the final yarns. Most common of all imperfections are thin or weak places, thick places, slubs, neps, and wild fibers, as shown schematically. During the subsequent processes of winding, warping, and slashing, not all but some of these imperfections create obstacles to steady and smooth working. Therefore, it is important to classify, quantify, and remove those imperfections which may cause the interruption of the operation. In other words, only ‘‘objectionable’’ faults need to be removed for trouble-free processing of the yarns. The ring-spinning operation produces a ring bobbin containing just a few grams of yarn which is unsuitable for the efficiency of further processing, such as warping, twisting, and quelling. This necessitates the preparation of a dense and uniform yarn package of sufficiently large size which can unwind in the subsequent operations without interruptions. The packages prepared for warping are normally cross-wound, containing several kilograms of yarns.

This implies that a number of knots or splices are introduced within each final package. Bear in mind, each knot or splice itself is an artificially introduced imperfection; therefore, the size of this knot or splice must be precisely controlled to avoid an unacceptable fault in the final fabric. In modern winding machines, knots and splices are tested photoelectrically for size, and only acceptable knots and splices are allowed to pass on to the winding package. In modern spinning processes, such as open end, friction and air jet, the spinning process itself produces a large cross-wound package, thus eliminating the winding operation.

Retraction winding machine for bulky yarn production:

This machine is equipped to carry out, in continuous mode, the shrinking of acrylic yarns and HB, also containing elastane, and the production of bulky yarns (blended and pre-dyed). It has a maximum winding speed of 1000 m. per minute and a shrinking field of 0-30 %. The operating principle, illustrated in Figure 59, is the following: the yarn is pneumatically inserted and, by means of a rotating distributor nozzle, wound in parallel coils around 4 aprons, which effect a slow translation movement. The yarn winding areas and part of the aprons are suspended in a forced air circulation chamber heated by electric resistances. This chamber (oven), whose temperature can reach 165° C, is where yarn retraction occurs; the yarn, supported only by the two upper aprons is perfectly free and able to shrink in ideal conditions. Exiting the shrinking chamber, the shrunken yarn passes through a cooling zone, after which it is unwound and then wound on to a new package. A over feeder roller reduces the tension of the yarn as it leaves the oven.