Pakspiny | Finisher Drawing Autoleveling | Drawing Auto leveling Principles | Drawing Scanning Roller

 Finisher Drawing Scanning Roller

Ø  Auto leveling

The introduction of the short-term, open-loop, electronic auto leveler on the RSB draw frame has produced, world wide, a very significantly improvement in yarn quality. In particular, yarn count variation, Uster evenness CV%, strength variation, Classimat minor defects and long thin places have been reduced.

Ø  Auto leveling principle

All slivers entering the draw frame pass through a bulk measuring head consisting of a par of tongue and groove scanning rollers. Variations in fiber mass are detected as changes in thickness. Movements of the scanning roller are transformed into voltages by a signal converter and forwarded to an electronic leveling processor.

RSB - Auto leveling System

The processor calculates the draft required to produce a leveled sliver. The correct values are fed to the servo drive that varies the speeds of the middle and back rolls. This changes the main draft to produce a leveled sliver. The timing of the leveling action is critically dependent upon the sliver speed, sliver path and staple length. The main motor drives the delivery rollers of the drafting system and the delivery speed remains constant. The servo, through the planetary gearing, drives the middle and back rollers of the drafting system and all other sliver feeding mechanisms.

Ø  Pre - Auto leveling setting

Very Important: Prior to adjusting the auto leveler, the draw frame has to be correctly set with the auto leveler switch off. The draft, roll settings, speeds, tension drafts and components have to be carefully optimized.

 

Ø  Autoleveler adjustments

The autoleveler should be set, adjusted and checked out as described in the machine manual. The following points should be observed: Scanning rollers The scanning rollers should be selected according to the amount of material being fed. The scanning roller distance, which corresponds to the cross-section of the total fed material, must be between 2.8 and 5.2 mm. The following table shows the recommended widths of the scanning rollers for various materials at different total sliver weights.

 

   The scanning rolls must the pressure is on with no  material  in place,The clearances between the tongue and groove should be 0.1 mm as shown in the diagram. Clearances should be checked at several points after partially turning the rollers.

 

Ø  Sliver funnel

The funnel should be clear of the scanning rollers with no material present and he pressure on.Scanning roller pressure,

Funnel Setting

 The scanning roller pressure has to adjusted using the regulator and pressure gauge, according to the material being processed. An indication for the correct amount of pressure is the minimum deviation when performing the “add/remove” sliver test.

Recommended scanning roller pressures are shown in the following chart.

XX - Standard application

X - Optional when needed

 

 

Ø  Desired target sliver weight

With the machine operational and the required number of slivers being fed, use the display menu 20.1 and select YES to calibrate the leveler. The machine must be running at the time of calibration, but the leveler must be turned OFF. The LED bar graph should zero itself (green) in the center of the display Turn leveler ON and run the machine to produce sufficient sliver for lab testing. Check sliver weight and Uster CV% and spectrogram.If the actual sliver weight is more than 1% different from the target sliver weight, change 20.2 in the menu and enter the actual sliver weight. Produce new sliver and check to see if it is acceptable. If not, continue to change 20.2. Note: The leveler is not designed to correct weight differences of less than 1%.If the target weight cannot be reached because the scanning thickness is outside the thickness 2.8 to 5.2 mm, the pair of scanning rollers must be changed to the next appropriate size.The leveling action point is in the main draft zone and is influenced by several factors that include:

 

• Tension of the sliver entering the drafting zone (VE)

• draft roll setting distance (HVD)

• Delivery speed

• characteristics

 

 Ø  Values of leveling action points

The leveling action point is set at menu 20.3 on the display.

Note:Drawframes delivered before August 2000, were equipped with a B91 incremental switch with 90 pulses per revolution.

Newer machines and replacement encoders produce 88 pulses per revolution. The following table lists the normal ranges of leveling action points (LAP) for some different materials: The following diagram shows the factors influencing the leveling action point.

 

To effectively arrive at the best (LAP), use the suggested value range, plus an intermediate value and produce sliver samples of 100 m of each for testing. Evaluate the CV% and spectrogram and select the best. Then run two additional tests to choose the preferred setting.Example of carded cotton. Suggested (LAP) range 1005 to 1023

From the first test, select the LAP which represents the best overall quality values. Spectrogram, CV1m CVm Use this selection process to perform the second and third series of LAP tests, to find the correct Leveling Action Point.

Note: Review the results and spectrograms before making a decision.

 

Ø  Leveling intensity

The leveling intensity setting ensures that the leveler will correct the sliver weight if there is a major swing in mass of the in feed material. To check and set the leveling intensity a “Sliver Test” has to be performed. The delivered sliver produced from the normal feed is compared with slivers produced from feeds of normal plus one sliver and normal minus one sliver. The % deviation is then corrected by changing the leveling intensity at 20.3 in the menu.