Roving is the last process before spinning. In addition to the evenness, spectrum, hairiness and other indicators that have a great influence on the spun yarn, uneven weight is also an important factor affecting the spun yarn. Uneven roving weight includes unevenness within a single spindle, unevenness between spindles, and more noteworthy weight deviations inside and outside the roving frame.
Main control of roving weight unevenness
1. Due to the difference in diameter of the bobbin and the hole diameter or bottom wear of the bobbin, poor coordination between the spindle groove and the spindle wing pin, the arc shape or improper position of the press palm, the different number of press palm turns, the different heights of the spindles, or other reasons The resulting uneven spindle operation will cause differences in the elongation law of the same row of rovings between spindles, affecting the evenness of the rovings. Coil waves can sometimes be found through the Pop diagram. Routine maintenance of machine parts and bobbins should be strengthened.
2. Due to the difference in elongation between large, medium and small yarns in the same spindle caused by improper selection of winding gears, the roving winding and forming gears should be reasonably configured to ensure that the tension of large, medium and small yarns in a doffing yarn is basically consistent. In addition, the tension of the roving also changes with the temperature and humidity of the workshop, which requires real-time replacement of the tension gear.
3. The friction coefficient of the false twister will affect the hairiness of the yarn. It is necessary to reasonably select the front and rear false twisters of the roving to reduce the tension difference between the front and rear rovings. The number of false twists in the front row is more than that in the rear row.
4. Placement of sliver cans. The sliver cans should be placed to avoid regular occurrences. For example, the sliver can for inner row yarn is placed close to the machine, and the sliver can for outer yarn row is placed far away from the machine. This will result in a long stroke of the sliver for outer yarn row, which will also Causes uneven yarn weight inside and outside. When placing it, you must also pay attention to keeping the cotton sliver perpendicular to the plane of the cotton guide to avoid tilting.
5. The rotation speed of the cotton guide roller must also be controlled well. Reduces accidental draft during sliver feeding.
6. Routine inspection and maintenance of carding and drawing equipment and quality control in the laboratory. Large deviations will also lead to serious quality problems such as large uneven weight of spun yarns and large strength CV.
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