SU1640644A1 - Method of detecting yarn flaws - Google Patents

Abstract

The invention relates to the textile industry and can be used in the control of threads for the presence of defects. and improves objectivity and accuracy of control. The current value of the thread diameter is measured, its ratio to the criterion of defect is compared with the permissible value of this ratio, and if the permissible ratio is exceeded, the presence of a defect is recorded. As a criterion of the defect, the value of the thread diameter offset from the current value by the distance providing the correlation independence of the values is used, and the ratio K x (t) / x 0 + AO is compared with the allowable value. where x (l) is the current value of the diameter of the thread, mm; x (1 + Al) value of the diameter of the thread offset from the current by Al, mm; Al is the distance between the current and the next cross section of the thread, ensuring the correlation independence of values, mm. The specified distance must exceed the correlation interval. 1 ill., 1 tab. 9 Ј

Description

The invention relates to the textile industry and can be used in the control of threads for the presence of defects.

The purpose of the invention is to increase objectivity and accuracy of control.

The drawing shows the curve of the change in the lobe of the thread along its length.

The method is carried out as follows.

The filament widths, the current and the distance between them, providing the correlation independence of the values, are measured, and then their ratio is determined. The distance between the two measured diameters (A I) must exceed the correlation interval. Each of the obtained ratios along the length of the thread is compared with the allowable value of Kd 1.5, and if the value is equal or exceeding this value, the presence of a defect is constructed.

The distance between the compared cross sections of the thread must meet certain requirements. If the value of АI is too small due to the monotony of some widespread defects and significant correlation of the neighboring cross sections x (1)

x (n and x (l + AI) the ratio h / d + dp may be

less cd (type II error). A blemish is detected if x (P

X (I + AI) -KA

Exodus from the drawing, x (l) x (l + AO + DH;

tga

(one)

(2) O)

(four)

Substituting (2) - (4) into (1), we get x (l + A1) + Ah y. x (l + AI) -14

1 + x (

1 + D1 x

TO;

x (1 + AI) Alfc (K-l) (L ± AD.

This condition is met by any AI distance greater than the correlation interval.

Textile yarns have a significant unevenness in thickness in a wide range of uneven wavelengths, with a drift of average thickness of the true product being observed. If the detection of defects in one implementation is carried out with the use of xsr found in another implementation, errors of detection of defects arise:

if the actual average value Xsr.f. more a priori (thick skip) Xsr .., then a slight thickening (relative to the background on which this thickening is observed) would be mistaken for a defect - a type I error;

if the actual average value is less than a priori (thin skip) xsr.f. xsr., then a large thickening will not be noticed - a mistake of the second kind.

If the detection of defects and the determination of the average are carried out according to the same implementation, errors of type 1 and II also occur, this is due to the fact that the length of the averaging must considerably exceed the possible length of the defect itself (supports 0.5–15 mm), and within the averaging segment, a drift of average thickness is also observed. Thus, there is a constant error of the known method of detecting defects when used in a technology that has a non-stationarity of the average thickness of the thread.

If, as the criterion of the defect, use the value of the thickness in the section that is separated from the considered one by the value of AI, and calculate the ratio

K-fl., K)

x (1-f AI) IJ

We then obtain a value that is invariant with respect to the mean value and generally relative to the absolute values of the thickness.

Thus, at a non-stationary thickness of the thread, the relation (5) will characterize the thickness variations relative to the neighboring section, i.e. background on which a flaw is observed.

PRI me R. Using the projection

the apparatus (micropots 5PO-1) obtain an enlarged image of yarn with a linear density of 50 tex and measure its diameter with a step of 1 mm. The results are tabulated. For an inaccuracy, an average is calculated.

the value of the diameter xsr is 0.45 mm and the ratios Ki x (l) / xsr are determined, as well as the ratios Ka x (l) / x (I + AI), where AI is the distance between the cross sections located at a distance of 20 mm apart. results

also tabulated.

In the table, Ki and < 2 > are greater than 1.5 (cd values). and combine a series of values. Then count the number of detected defects

corresponding to the number of groups of values greater than 1.5 kd.

As can be seen from the table, this method made it possible to detect a yarn flaw with a length of 3 mm, while comparing the current value

the cross section with the average value is recorded deviations of the thickness of the yarn, which are not in fact defects.

Claims (1)

Invention Formula The method of detecting thread defects, which consists in measuring the current value of the thread diameter, comparing the value of its relation to the criterion of the defect with the permissible value of this ratio and fixing the defect when the permissible value is exceeded, characterized in that, in order to increase objectivity and accuracy of control, the value of the thread width displaced relative to the current value by a distance providing correlation independence of values is used as a criterion of blemish; to-x (1) x (1 + D) where x (1) is the current value of the diameter of the thread, mm; x (l + AI) - the value of the diameter of the thread, offset from the current on the AI, mm; АI is the distance between the current and the next cross section of the thread, providing the correlation independence of values, mm. xW xdl x (