Question 1: What is the reason for the mechanical wave at 1m of the draw?
Answer: Taking a company using a DX500 draw frame as an example, mechanical waves often appear at 0.97 m of cooked sliver. The reasons are analyzed as follows.
1) The circle wave formed by the circle effect. The DX500 draw frame is equipped with a sliver can with a diameter of 500 mm. The winding diameter of the upper coil is 348 mm. The circumference of each coil is 1.093 m, which is basically consistent with the mechanical wave with a wavelength of 0.97 m. The coil wave Generally, it can be eliminated after the roving process and will not affect the yarn quality.
2) Mechanical waves caused by poor condition of the rear roller or rear rubber roller. For example, the rear roller is tangled, the bearing is short of oil, and the distance moves; the rear rubber roller is tangled, shakes, wanders left and right, and the rubber roller sleeve is short of oil and vibrates. This wavelength is (35π×8.6)/1000=0.945 m, which is basically consistent with the mechanical wave at 0.97 m on the spectrum.
3) Mechanical waves formed by transformation gears and crown gears. The inspection found that mechanical waves at 0.97 m will be generated when the conversion gear and the crown tooth gear are worn or improperly meshed.
By increasing the tension draft between the roller and the upper coil disc, the draft ratio is increased from 1.016 times to 1.046 times, and the draft is dipped in No. 93 gasoline or industrial Wipe the coiled inclined tube with alcohol cloth to basically eliminate the coiled wave. A combination of dynamic maintenance and periodic maintenance is adopted, focusing on strengthening the inspection of key components in the drafting area and oil bath gearbox. Equipment inspectors strictly inspect and accept, and craftsmen conduct random inspections to ensure the condition of the equipment. Through the above measures, the mechanical wave at 0.97 m in the draw spectrum has been basically eliminated, the draw CV has also been reduced from 3.85% to less than 3.15%, and user feedback on long thick and long thin yarn defects has also been reduced.
Question 2: The main reason for many neps in drawing?
Answer: The main reasons for the large number of neps in drawing are as follows:
1) Roller gauge: The gauge affects the number of floating fibers and hook fibers. Straightening effect, thereby affecting the nep growth rate.
2) Drafting multiple: affects the proportion and speed ratio of fast and slow fibers and affects the nep growth rate.
3) Drafting type: affects the ability to control fibers and affects the nep growth rate.
4) Drafting distribution: Drafting distribution adjusts the drafting ratio of the front and rear drafting zones, and reasonably handles the hook fibers in different directions, thereby reducing the growth rate of neps. .
5) Sliver sliver quantity: affects the number of fibers in the drafting zone, which in turn affects the ability to control fibers in the drafting zone.
6) The smoothness of the drafting channel: If the channel is not smooth, the outer fibers of the sliver will be rubbed and form neps.
7) Temperature and humidity: directly affects the physical properties and spinnability of the fiber. If the temperature and humidity are too low, the fibers will be brittle and hairy, and it is easy to form reverse fibers on the surface of the sliver and increase neps. If the temperature and humidity are too high, the fiber will become sticky and soft, and it will easily wrap around the drafting parts and increase neps.
8) Operation: Careless operation when changing the can and rewinding the sliver can easily cause sliver tops.
9) The sliver can exit direction and position: the sliver exit direction of the sliver can should avoid the slits to prevent sliver shaving; the sliver exit direction should be straight up and down. When the sliver can is too far away from the sliver guide frame, the sliver guide angle is too small and it is easy to shave the sliver.
10) Clean the velvet cover: The flowers hanging from the clean velvet cover will fall into the cotton net, causing an increase in neps.
11) Down-suction air volume: The down-suction air volume is too large, causing fibers on the surface of the cotton web to scatter and increase neps.
12) Drafting area: The drafting area is not clean, and the accumulated short lint falls into the cotton net, causing an increase in neps. </p
