Wednesday, March 25, 2020

PATTERNING OR RIBBON FORMATION ( RIBBONING) IN YARN WINDING PROCESS, CAUSES, AND REMEDIES


ANTIPATTERNING DEVICE OR RIBBON BREAKER:

Before knowing about anti patterning device, it is necessary to know about patterning or ribbon formation in yarn winding process. How and when does the ribbon formation take place?

Ribbon formation or patterning:

This is a yarn package defect. This defect gets occurred during yarn winding process. 'The patterning or ribbon formation (Ribboning ) can be defined as a yarn package defect to be occurring during yarn winding process, in which the yarn coils get laid on the top of the previous yarn coil'.
In other words, we can say that the yarn coils follow similar path repeatedly during winding. This repeatedly continuous yarn coils path causes patterning or Ribboning ( ribbon formation) in the yarn package getting wound.

This situation gets created when traverse ratio reaches to an integer value. It has been observed that some patterning also occurs when values of traverse ratios that differ from an integer by 0.5, 0.25 etc.

At the starting of winding, the diameter of empty package is less than traverse drum. As the winding gets begins, the package diameter increases rapidly. When the package diameter gets equal to traverse drum, the patterning zone gets started. The ratio between rotational speed of traverse drum and package  gets equal to whole number (1). As soon as diameter of package gets increased the patterning zone gets ended. This kind of situation created every time when the ratio between rotational speed between traverse drum and package gets equal to an integer ( whole number. The patterning can be classified as below:


Major patterning:

When the package diameter gets relatively large, the rate of increase of package diameter gets slow. We can say that diameter change takes long time. In this stage, the patterning results for long time.

Minor patterning:

This kind of patterning results at the starting of winding. Since the rate of change of package diameter gets very fast at the time of starting, so that the patterning persist for very short period.

ANTI PATTERNING DEVICE:

If a yarn package has patterning or Ribboning defect in it, the yarn unwinding gets difficult during uses of this kind of package. A lot of end breakages get occurred during yarn unwinding. There are different types of anti patterning ( Ribboning ) devices used to prevent the patterning or Ribboning defect in the yarn package. The some of anti patterning systems being used in different winding machines are given below:

Propack system of anti-patterning by Schlafhorst:

This anti-patterning device has been designed and developed by Schlafhorst. It is a cradle anti-patterning system. As we know patterning creates when the number of yarn coils laid on the package per double traverse is a whole number. At the time of ribbon formation, the ratio between traverse drum speed and package speed reaches a critical value. The The computer of the "propack system" continuously monitors the speed of traverse drum and package speed and determines the ratios between traverse drum speed and package rotational speed. Whenever computer reads that critical speed ratio is about to touch patterning zone, the propack system comes into action immediately. The propack system lowers the cradle pressure by a pre-determined amount. In this way, the rotational speed of the package also gets decreased below the critical patterning speed till the package diameter gets adjusted to a value above the pattern zone. After crossing the patterning zone, the propack system system again send a command to mechanism, and the cradle pressure immediately returns in it previous value.

Semi-conductor device (TRIAC) anti-patterning device:

The Muratec Mach(Japan) has developed this anti-patterning device. This is an electronic device. It works on the basis of semi-conductor. Anti-patterning action is achieved with the help of pre-feeding of programme for start and stop durations (period) of the traverse drum motor. In this way, the speed variation cycle gets adjusted. The speed of traverse drum and therefore, the package increases or decreases constantly to prevent the ratios of their speeds to touch the critical value which creates patterning.

Double pitch drum (anti-patterning device)

This anti-patterning system has been developed by Murata ( Japan). This anti patterning system is known as Pac21.  This monitor all those critical parameters which are cause patterning. When control unit of Pac21 reads that patterning zone is about to touch, it sends a command to change the position of yarn from one groove to another groove of the same drum to prevent the patterning. In this way, at the time of ribbon formation zones the groove position changing mechanism switch over the yarn from winding at 2W to 2.5W.  It is suitable for all counts, types of yarns and package shapes.

Computer Aided Package (C. A. P. ) anti-patterning device by Savio:

This anti-patterning device has been developed by Savio. It is an electronic device. The drum and package diameter ratio gets read and regulated with the help of a computerized system. Each winding head computer controls the yarn deposited on the package. When the system reads that the patterning zone is about to touch, it  automatically intervenes with a servomotor to modify the drive ratio between package and the drum. The Savio claims that this system produces perfect package without patterning.

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