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Drawing Sliver Coiling

When coiling sliver into the can it is important to maintain: a smooth compacted sliver with low hairiness, fill the can in the correct manner and minimize dust / trash accumulations in the coiler tube. 

 

 

    

Ø  Coiler tube

The form of the coiler tube has been developed to enable the sliver to move with minimal interference into the can. The tube is normally made of stainless steel, which is wear resistant and suitable for most fibers. There are a very few exceptions in which the sliver is not compatible with the frictional characteristics of steel, and will not freely slide through the tube. In this case it may be necessary to use a brass coiler tube.The coiler tube and plate have to be selected to suit the sliver weight and the diameter of the sliver can. 

Ø  Coiler tube inside diameters

 To obtain a smooth and compacted sliver the coiler tube should be as small as practicable. If the tube diameter is too large for the sliver, the sliver will have a tendency to:

·         Be hairy,

·         create difficulties during withdrawal from the can,

·         have a reduced sliver cohesion.

·         detailed Rieter recommendations can be found in the machine manual

 

Ø  Sliver deposit

 Depending upon the sliver can size, the sliver is coiled either “over center” in cans 225 to 600 mm diameter or “under center” (some references use “onto the center”) in cans 800 to 1000 mm diameter.

Ø  Coiler settings

To maintain good quality coiling of the sliver, the following points of the coiler have to be correctly set:

Coiler speed depending upon material and sliver weight. The speed must not be excessive and stretch the sliver, nor too slow and lay the sliver unevenly in the can  location (eccentricity) to build a column diameter 10 mm smaller than the can’s inside diameter. This should be checked when the can is 75 % full,Can table speed to adjust the coil spacing so that the sliver coils are side by side, not overlapping and not spaced apart.Length of sliver in a full can must not be excessive. An overfilled can creates problems of sliver disturbance and scuffing which leads to drafting problems at the subsequent processes.

·         The can condition has to correct, damaged and out-of round cans cause many problems and a deterioration of sliver quality.

·         The cans must be the required size and set relative to the coiler plate.

·         The can spring length and pressure must be correct for the material being processed.

·         The coiling conditions have to be checked and, if necessary adjusted, with any change of: Sliver weight, - Material,

Coiler speed

Check coiler speed

 

 The coiler speed is too low. The sliver (1) is pulled to the outside of the coiler exit. This pushes the coils onto each other and the sliver tends to pull apart when being removed from the can.

The coiler speed is correct. The sliver (2) leaves coiler plate at back of the kidney-shaped.

The coiler speed is too high. The sliver is pulled to the inside of the coiler exit.

The sliver is stretched, the coils will be deformed and periodic draft faults may occur.

 

 

Ø  Correct coiler speed

 Coil diameter (A) is evenly round. Distance (a) between the coils (A) remains uniform around the can.The form of the sliver column (2) is evenly round and 5 mm clear of the can side (1)

  Coiler Speed Too Low

 The coils are too wavy.

The distance (a) between the coils (A) is relatively uniform.

The Diameter of the sliver column (2) is too large and is equal to or greater than the inside diameter of the can (1).

Ø  Coiler speed too high

 

Sliver coils (A) are out of round and are not consistent. The coils are drop shaped with the tip pointing toward the can inside wall (1) The distance (a) between the coils varies from one coil to another. The sliver column (2) is out of round. The sliver column (2) is too small and the clearance between the column and the inside of the can is more than 5 mm.

 

Coiler speed correct

 

Coiler speed too low

 

 

Coiler speed to high

 

   Sliver coils per can revolution

 

The sliver coils per layer is obtained by dividing the speed (rpm) of the coiler by the rotational speed of the can table. With larger diameter cans the number of coils per layer increases to maintain optimal coiling and can filling.

nD = Relationship of coiler rpm to can table rpm

nD = coiler rpm

can table rpm

The following can be used as a guideline

• Ø  Can eccentricity

   The outside diameter of the sliver column is primarily established by the relative positions of the centers of the coiler and the can table. This distance is referred to as the eccentricity. If the can table is moved to reduce the eccentricity the sliver column will be reduced, and conversely the column will be increased if the table is moved to increase the eccentricity. The setting of the can table eccentricity is normally not changed.

  However, it may be necessary to make a re- adjustment if there is a change to fibers of greatly different bulk characteristics, such as cotton to acrylic fibers.