Long slubs are yarn defects that easily occur in spinning mills and are extremely harmful. When woven onto the cloth surface, thick warp and weft errors (weaving) or rung defects (knitting) will form. Such yarn defects are difficult to repair and may even cause defects such as shearing and shearing, resulting in large losses and sometimes financial claims from customers. Occasional long coarse defects mainly occur in the pre-spinning and coarsening process, mainly due to operational reasons, equipment and other reasons. Improper process design can also produce such yarn defects. Today, we analyze the causes of roving yarn defects from the aspects of equipment such as the stripping knife roller, roving flyer and false twister under the roving frame, and the traveling blow pipe of the roving frame. We hope to provide some useful reference for the production management of textile enterprises.
01 How to eliminate large thick place yarn defects in roving
There are often large thick place yarn defects in roving strips that vary in color, thickness, and length. Some are distributed on the surface of the roving, and some are mixed in the package. These yarn defects form slubs, slubs and other yarn defects after the fine yarn is stretched. The color and shape of this kind of large slub yarn defect looks like a mouse, so it is commonly known as “cotton mouse”. This kind of yarn defect has two pointed ends and a thick middle. Generally, the short one is 30 mm and the long one is 56 mm. Some are gray, and some are gray. The color is light yellow.
After analysis, it was found that this yarn defect is caused by the roving flyer and false twister. The flyer false twister is the main component of the roving yarn. Due to processing errors, the diameter of the inner ring of the false twister is often larger than the diameter of the inner hole of the flyer, causing interference. When the false twister is fully inserted, its inner ring will It is squeezed and deformed by the inner hole of the spindle flyer to form an inward flange, and there are often burrs here. When the roving strip passes through, it is easy to form large slugs with sharp ends and a thick middle. When the large slugs accumulate, they become thicker and cannot be hung. When it does, it will fall off along the false twister and wrap around the roving spindle with the roving strips, forming yarn defects.
In order to solve this problem, we removed the spindle flyer, opened the stainless steel tube, further corrected and polished the deep recess of the spindle flyer, removed burrs, and then pressed the stainless steel tube and spindle flyer together. After repair, there is no interference between the false twister and the spindle flyer, thus eliminating the large slub roving.
02 Improvement of the stripping knife roller under the roving frame
FA458 and JWF1415 rovings The cotton stripping knife under the machine performs reciprocating motion by rotating the lower swing axis at its rear end. Both sides of the front end of the cotton stripping knife are connected to rollers. The two rollers run in a limited track and cooperate with the lower cotton stripping knife to complete the task of cleaning the flannel.
The lower cotton stripping knife roller is composed of a small shaft and a roller. Careful analysis of the operation conditions of the small shaft and roller will reveal that the exposed gap in the inner cavity of the roller and the lateral movement gap between the small shaft and the roller are relatively large. Large, flying particles and impurities can easily enter it, causing the rollers to run sluggishly and accelerating the wear of the rollers. Due to the inflexible operation of the roller, the normal operation of the cotton stripping knife and the dust shield connected to the cotton stripping knife is seriously affected. The reciprocating operation of the lower cotton scraper is blocked, and the lower cleaning velvet cover is easily damaged, which accelerates the wear of the lower cotton scraper and makes it difficult for the lower cotton scraper to strip cotton in time. At the same time, the shaking of the dust shield causes dust to fly to other areas when the air blows. direction without being completely sucked away by the suction points on the countertop, workshop cleanliness is affected.
The small shaft and roller are an inseparable whole. When replacing, the small shaft and roller are not interchangeable, the replacement volume is large, and the machine material consumption is high. Since the roller is made of nylon and has a large proportion of the cavity, it will deform greatly when parking, which will also hinder the operation of the roller.
In response to existing problems, the company made the following improvements to the rollers: the original fixed roller end rivet cap of the small shaft was changed to a screw with a length of 5 mm and a diameter of 4 mm; the length of the roller shaft section was changed to 6 mm in diameter and 5 mm in diameter; the other fixed end of the small shaft is changed to a screw with a length of 8 mm and a diameter of 4 mm; two 685 sealed bearings are used to replace the original nylon rollers, and the outer ring of the bearing is wrapped with a thickness of 0.5 mm elastic rubber ring to enhance its wear resistance; 2 M4 nuts fix 2 bearings and rollers respectively.
The improved roller can move freely within its track and has a long working life. Even if it fails, the problematic part can be disassembled and replaced, saving costs. Due to the good wear resistance of the outer rubber ring of the bearing, unfavorable phenomena such as roller beating or sluggishness are better controlled, thus solving the previous problems and ensuring that the lower cotton stripping knife can correctly peel off impurities and short lint, effectively reducing the amount of roving yarn. defect.
03 Improvement of the traveling blow tube of the roving frame
In the roving process, if the flying flowers and short lint in the drafting and winding channel of the roving frame cannot be removed in time, It is easy to produce yarn defects. In the original blowing and suction system of the roving frame, the blowing pipe is short and there are few branch pipes, so many places cannot be blown. It mainly relies on the operator to use brushes and bamboo poles to clean the flying lint and other impurities adhered to the surface of each process part during doffing. The cleaning effect is not good, resulting in many yarn defects.
To this end, the blow pipe was improved as follows: In order to reduce the lint on the front roller and the accumulation of lint in the groove, a hole with a diameter of 15 mm was drilled on the blow riser directly opposite the front roller. Put a bell mouth and tighten it at both ends (no air leakage); when stopping and starting, you will often find that the accumulated flowers fall out of the spindle wing channel, which can easily cause yarn defects on the roving. To this end, drill two holes with a diameter of 10 mm in the horizontal pipe, and connect the front row of 10 mm×750 mm diameter pipes and the rear row of 10 mm×850 mm diameter pipes with the drilled holes. Aim at the mouth of the false twister. There is often accumulation of flowers on the shoulders of the spindle wings. The blower riser can be lengthened.. The function of the air blowing port on the top rib cover is retained.
Through practice, after the above improvement, there are very few impurities falling in the flyer channel, which improves the yarn quality, increases production efficiency, and reduces the labor intensity of the lathe operator.
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