The roving is output from the front roller jaws and is wound to the bobbin through the flyer. A certain degree of tension. Bear a certain tension to ensure a certain roving tension. Since the roving has less twist and lower strength, slight changes in the roving tension can affect the weight unevenness and evenness of the roving. Therefore, maintaining proper roving tension during spinning will not damage the uniformity of the whiskers and rovings, but also ensure that the rovings are tightly wound and a certain winding density is ensured. Reasonable roving tension is a necessary condition to ensure the normal production of roving and ensure the quality of roving. Roving elongation is an important indicator that indirectly reflects the roving tension. If the elongation of the roving is too large or too small, it will affect the evenness and weight unevenness of the roving; if the elongation of the roving is too large, and the difference between the elongation of the large, medium and small yarns is too large, the end breakage rate of the roving will be affected. rise. 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 type bar thickness gauge, meter ruler, a set of wrenches, a set of winding conversion gears and forming conversion gears, and a number of 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 in the same spindle. The tension control of roving-doffing should be realized by adjusting the tension teeth according to the situation of detecting the tension of roving. The detection of roving tension includes direct side test method and indirect side test method. The former can directly test the tension of the spinning section, which has the advantage of fast and error-free. However, due to the influence of factors such as instruments and testing methods, there are certain inconveniences in actual use. At present, roving elongation is mostly used to indirectly reflect roving tension. For the test of roving elongation, the factory uses the percentage of the difference between the actual length of the yarn wound on 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 Trial cycle and sampling Each unit is tested at least once a month, and each unit is tested with 2 rovings in the front and rear rows. Routine tests generally only check the elongation of small yarns and large yarns on the side. The test is carried out on roving small yarns or large yarns, respectively. The small yarn test generally starts after the empty tube is wound on the third layer; the large yarn is tested 4 to 5 layers before the full yarn (controlled by the specified full yarn length). After the raw material, temperature and humidity, process adjustment and size repair, the test of roving elongation should be carried out in time. 2.2 Detection steps (1) Select 2 roving bobbins with standard diameters in the front row and rear row (2) Turn off the machine, and fix the revolution table (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 the second powder mark on the output whisker of the front roller, and then drive. (4) The revolution meter counts to about 500 revolutions, or after visual inspection, the roller rotates for about 60 revolutions and then stops, and then make a powder mark at the mark of the front roller output whisker. (5) Start the car, and turn off the car for sampling after the powder is wound to the roving bobbin t. (6) Use a cylinder length measuring device to measure the actual length of the roving between the two powders in the experiment. When the length of the yarn tail is less than 1m, measure with a ruler, accurate to 1cm. 2.3 Detection data processing and detection analysis (1) Calculate the length of the roving. The calculated length should be accurate to lcm. Calculated length of roving = Roller revolutions before actual measurement×π×The calculated length of the roving with the diameter of the front roller = the actual number of revolutions of the rear roller×The draft ratio of the rear roller to the front roller×π×Front Roller Diameter (2) Roving Elongation. Calculate the elongation of large and small yarns of the 4 spindles in the front and rear rows and the average elongation of large and small yarns of the 4 spindles. The elongation of the roving = [(the actual length of the roving - the calculated length of the roving) / the calculated length of the roving]×The elongation of 100% roving is generally required to be 1% to 2% (maximum no more than 25%). The difference in roving elongation between machines, front and rear rows, and 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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