| Abstrakt: |
There are many mechanical faults in cotton processing which may cause periodic variations in the resulting yarn, roving, or sliver. Each of these defects causes a particular pattern of thick and thin places in the resulting material. An eccentric part (roll or gear) on a drawing, roving, or spinning frame results in a wavy pattern of thick and thin places in the material. The pattern formed in the material by a flat spot in the top roll is dependent upon the position (front, second, third, or back) on the particular frame. A flat spot in the back roll position has very little effect on the resulting material. In the third roll position (four roll frame) it yields a thin place directly followed by a thick spot, while a defective front roll causes periodic thick places in the material.Defective bottom rolls on the drawing frame affect the sliver differently, depending upon the position on the frame. Defective drafting rolls used primarily as delivery rolls have a greater effect on the resulting material than defective rolls used primarily as feed rolls. Most of these mechanical faults have a particular pattern which can be distinguished by proper use of the Uniformity Analyzer.There are certain settings (pen average, pen sensitivity, chart speed, and material speed) which can be used on the Brush Uniformity Analyzer to assist in the search for periodic variations. The particular setting to use when searching for periodicities is generally dependent upon the distance between the expected periodic variation. For closely spaced periods (3 to 10 in.) in the material, a fast chart speed (25 mm./sec. or 125 mm./sec.) and the pen average at position 0 or 1 is generally used. A slow chart speed (5 mm./sec.) and the pen average at position 2 or 3 will illustrate longer periodic variations. The pen sensitivity control is generally used to increase the amplitude of the variations on the chart after the pen average and chart speed have been selected. [ABSTRACT FROM PUBLISHER] |
