Thursday, 13 August 2009

Warp Knitting | Yarn Tension Compensation Device | WA II 4 Q

This device attached on Karl Mayer direct warping machine type DS 21/30 or DS 30/52 NC or DNC.
To understand how this device work is very importance in order to get good quality of warp beam,
This article purpose is give some more knowledge to people who involve on warp knitting business and user of
Karl Mayer's warping machine.
This article taken from many sources and the experience of the writer.
Hope fully will be use full for reader who involve at warp knitting business and the people who involve directly as the operator
or technicians of warping machine build by Karl Mayer Company.



Purpose:

This unit serves to created the desired yarn tension in the front of warp beam, to stabilize a yarn sheet and to compensate the yarns tension differences.
Function:
The yarns sheet runs through a pair of rollers. The stabilizing and compensating effect increases by raising deviation angle of the rollers pair, but at the same time also the yarns tension and tension peaks when the machine stopped due some reasons.
The ideal deviation angle of the rollers varies according to the various materials used and has to be determined in practice.

What Does 4Q means?
4 Q= 4 quadrant drive, driving and braking in both turning directions.(operating all four quadrants).
The possible operating mode of the drive can be represented by means of the four quadrants of the torque and number of revolution diagram ( operating diagram).



Operation

The warping tension results from the following four factors;
F0 = Tension caused by the package draw off.
F1 = Tension caused by the yarn tensioner.
F2= Tension caused by general friction.
F3 = Tension caused on the leveling roller unit (increase or decrease).



1- Yarn package in the creel.
2- Yarn tensioner.
3- Leveling roller unit.
4- Yarn tension regulator.
5- Warping machine.

The total tension is equal to the sum of the factors F0 through F3.In general, the package draw-off tension F0 increases as the package diameter decreases. The factor F1 doesn’t depend of the warping speed. The factor F2 depend of the warping speed and remains constants at equal speed ,In order to keep the total yarn tension constant ,increasing factor F0 (package draw-off tension) has to be compensated. This compensation done by drive regulation (driving or braking) on the leveling roller unit (WA).

Regulating Unit of the Leveling Roller

The 4 Q drive allows to increase total yarn tension by 70 Newton or to reduce it by 80 Newton .
When producing the master beam or working without computer (non NC type),
the desired total yarn tensions is set on a potentiometer at the machine and monitored automatically by electronic control over the entire warping process.

The Essential Advantage of This System;

1. Permanent control of the yarn sheet tension (white master beam or when working without computer).
2. Constant yarn tension regardless of the warping speed.
3. Equal beams circumference at equal number of revolutions.
4. Simple handling of tension change.
5. Permanent control of the layer thicknesses of the beams.
6. Driving and braking.
7. Constant yarn tension immediately after start-up of the machine.

Taking into Operation of WA roller

1. Yarn Tension of the Creel.

The yarn tension caused by the creel mainly the result of two changing factors :
Braking – The braking force of the yarn tensioners can be change depend of the machine construction and the respective warping task .
Yarn Package – The yarn tension change in the functions of yarn package diameter.

Advantages resulting from the use of KFD yarn tensioner.
- Yarn tension difference occurring with the large and small yarn package diameter are compensate.
- The same yarn tension is ensure at different production speed.

2. Regulating range of the leveling roller unit

The regulating unit must compensate the changing yarn tensions coming from the creel. Therefore ,it always to be adjusted in away that there is sufficient regulating reserve.

Total Yarn Tension Required

This must be know when warping is started. It is determined in the instructions of the yarn manufactures or by the requirements in the processing sectional beam.
Actual Total Yarn Tension
The yarn tension is measured shortly before the sectional beam on at least 10 yarns and the average yarns tension is determined in this way. The average yarn tension multiplied by the number of the yarns is the actual total yarn tension.
Setting the Required Yarn Tension
Turn the regulator on the switch cabinet carefully until the desired yarn tensions is reached .
Measure the yarn tension continually during the setting increasing.

3. Working Range |Pressure Pick-up|DMD Load Cell|Positions:200 N|1000N

The tasks to determine the DMD load cell position through the total yarn tension. The total yarn tension is calculated on the basis of trite thickness (dtex) and the number of the yarns:

Example 1 : 44 dtex ,1000 yarns
Formula : (0,2 * X 44 dtex ) X 1000 yarns = 8.800 grams = approx 88 Newton
DMD load cell position: 200 Newton

Example 2 : 167 dtex,1000 yarns
Formula : (0,2* x 167 dtex) X 1000 yarns = 33.400 grams = approx 334 Newton
DMD load cell position:1000 Newton
*0,2 is conversion factor and recommended by Karl Mayer.

The following conversion factors are suggested :
Polyamide (Nylon): 0,15.....0,2
Polyester : 0,2.....0,3
Monofilament: 0,12.....0,2


This table provide a theoretical guide line only and doesn't considering slippage (yarn properties).

Example :
Total yarn tension required 8,8 kg
Yarn tension regulator on position 4
a. Switch on the main switch of the warping plant.
b. Set the yarn tension regulator to the value taken from the table above.
c. Start the warping plant and wait until the present warping speed is reached.
d. Measure the actual total yarn tension.
e. Set the desire yarn tension by means of the yarn tension regulator by turning it slowly.
Turning to the right = higher yarn tension.
Turning to the left = less yarn tension.

4. Mechanical Basic Setting

Check the position of the pressure pick-up (1) .Is the pressure pick-up within the desired working range (see working range)?

A change has to be done as follows:
- Remove the screw (2).
- Reposition of the pressure pick-up(1) and fasten its by means of screw (2).
- Carry out the null balance of the pressure pick-up,(see electrical basic setting).




Check the parallelism of the yarn tension rail :e.g. improper transport of the leveling roller unit.

- Check the parallelism of the tension rail at both tension rail ends by means of the gauge (3),the gauge is supplied with the unit.
- If the corrections is required ,loosen the screw (4) ,align the tension rail and tighten the screw (4) again.

5. Electrical Basic Setting
The electrical setting need carry out by service personnel of Karl Mayer company,please leave a comment for further assistance.

1 comments:

Jeba Sheela said...

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