The roving is output from the front roller jaws, and during the process of winding to the bobbin through the flyer, the sliver must overcome the frictional force of the top of the flyer, the hollow arm and the pressure palm on the roving. The roving should always be maintained during the winding process. A certain degree of tension. Withstand a certain tension to ensure a certain roving tension. Because the roving has a small twist and low strength, slight changes in the roving tension will affect the weight unevenness and evenness of the roving. Therefore, the proper roving tension is maintained during spinning, which will not damage the uniformity of the sliver and roving, but also ensure that the roving is tightly wound to ensure a certain winding density. Reasonable roving tension is a necessary condition to ensure the normal production of roving and to ensure the quality of roving. Roving elongation is an important indicator that indirectly reflects the tension of roving. If the elongation of the roving is too large or too small, it will affect the unevenness of the roving and the unevenness of the weight; if the elongation of the roving is too large, the elongation difference of the large, medium and small yarns will be too large, which will cause the end breakage of the roving. Elevated. Therefore, the elongation of the roving must be measured periodically, and the elongation of the roving must be controlled within a certain range by adjusting the process parameters of the winding part. 1 Testing instruments and
testing principles 1.1 Experimental instruments and utensils roving frame, Y301 strip thickness measuring device, meter ruler, one set of wrenches, one set of winding change gears and forming change gears, and several red chalks. 1.2 Detection principle The control of roving tension includes two aspects: the size of roving tension and the difference of roving tension. The difference in tension includes the difference between machines, the difference between the front and rear rows of the same machine, the difference between different spindles in the same row, and the difference between large, medium and small yarns of the same spindle. The tension control of the roving and the doffing should be realized by adjusting the tension teeth and other methods according to the detection of the roving tension. The detection of roving tension includes the direct side test method and the indirect side test method. The former can directly test the tension of the spinning section, which has the advantages of fast and error-free. However, due to the influence of instruments and testing methods, there are certain inconveniences in actual use. At present, the elongation of the roving is often used to indirectly reflect the tension of the roving. The test of roving elongation is expressed by the factory as the percentage of the difference between the actual length of the bobbin and the calculated length output by the front roller and the calculated length output by the front roller at the same time. 2 Testing process 2.1 Test boarding cycle and sampling Each machine is tested at least once a month, and each machine tests two rovings in the front and back rows each time. The conventional test generally only examines the elongation of the side small yarn and the large yarn. The test is carried out when the roving is small or large. The small yarn test generally starts after the empty tube is wound on the third layer; the large yarn is tested when it leaves the full yarn 4 to 5 layers (according to the specified full yarn length). After the raw materials, temperature and humidity, process adjustment are large and the size is repaired, the roving elongation test should be carried out in time. 2.2 Detection steps (1) Select two roving bobbins whose diameters meet the standard in the front and rear rows (2) Turn off the car, and fix the revolution meter (with more than 3 digits) on the front roller shaft head. If there is no revolution meter, you can make a mark on the shaft head of the rear roller (3) Apply two powder marks on the output strip of the front roller and drive. (4) The revolution meter counts to about 500 revolutions, or after visual inspection, the roller turns around 60 revolutions and then stops, and then make a fan mark at the place where the front roller outputs the beard fan mark. (5) Start the car, wait for the powder to be wound on the roving bobbin t and then close the car for sampling. (6) Use a cylindrical length measuring device to measure the actual length of the roving between the two powder marks in the experiment. When the yarn tail is less than 1m long, measure it with a ruler to the nearest 1cm. 2.3 Detection data processing and detection analysis (1) Calculate the length of the roving. The calculated length should be accurate to 1cm. Roving calculated length u003d measured front roller revolutions × π × front roller diameter roving calculated length u003d measured rear roller revolutions × rear roller ~ draft multiples of the front roller × π × front roller diameter (2) Roving elongation. Calculate the elongation of the large and small yarns of the front and back rows of 4 spindles and the average elongation of the large and small yarns of the 4 spindles. Roving elongationu003d[(actual length of roving-calculated length of roving)/calculated length of roving] ×100% Roving elongation is generally required to be 1% to 2% (maximum not more than 25%). The roving elongation difference between the machines, the front and rear rows, and the large and small yarns is required to be less than or equal to 1.5%. If it exceeds the range, it should be adjusted in time.
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