运用声学的方法和装置测量棉纤维中的麦克隆指数

1、运用声学的方法和装置测量棉纤维中的麦克隆指数运用声学的方法和装置测量棉纤维中的麦克隆指数in 1993 the new state standard rst uz 604-93 cotton fibre. technical conditions was implemented in republic of uzbekistan. in accordanee with this standard the micronaire index was added to the number of the important characteristics of cotton fiber, which

2、 widely used on the world trade and characterizing the linear density and maturity of the fibre.the base range of a micronaire index in world trade of upland cotton is 3,5 - 4,9. if the value is below 3.5 and more than 4,9 the discount is made from the price of cotton fibre. in this regard, it is im

3、portant to control instrumentally a micronaire index at preparation and processing of seed cotton, and also at developing new varieties of cotton.for definition of a micronaire index in the world practice a method of air permeability is used, which realized in such devices as umicronaire”， “fibrofin

4、e”，“portar” etc. these devices are also entered into hvi measuring systems.recently in various industries the acoustic devices are used for non destructive testi ng of quality of fibrous materials.devices that use acoustic methods are simple in design and reliable in operation. for accuracy, they ar

5、e not inferior to similar devices using, for example, the method of air permeability of samples of cotton fiber in the air stream.in 口 it is shown, that by using the acoustic method it is possible to determine the grade of a seed cotton and cotton fibre by breaking load of fiber. at the same time th

6、e dependence of acoustic attenuation in a sample of fibers from their breaking load was used.in 2, the results of studies of the phase d iff ere nee depe nding on sound waves passing through a sample of cotton fiber from the micronaire index, the coefficient of linear density and maturity of cotton

7、fibers are shown.this paper discusses the use of acoustic method for measuring of micronaire index from the damping of acoustic oscillations.the basis of the acoustic measurement method is the process of distribution of acoustic vibrations in a sample of cotton, placed in the chamber and compacted i

8、n the form of a cylindrical tube with a flat base. the direction of passage of sound fluctuations is perpendicular to the bases. a sample of fibers is possible to simulate a two-comp on ent isotropic porous medium (fiber, air). with the passage of a plane sound wave through such an environment there

9、 will be loss of energy due to friction of the fiber, which will lead to a change in the pressure amplitude of sound vibrations.to carry out experimental studies on the implementation of an acoustic method for measuring the micronaire index in the taxtasanoat ilmiy markazi” science centre was design

10、ed and constructed an experimental sample of acoustic in strument, which appeara nee and block diagram are shown in figures 1 and 2.figure i.the appearance of acoustic micronaire instrumentfigure 2. the block diagram of acoustic micronaire instrumentthe device operates as follows.sound vibrati ons,

11、gen erated by a gen era tor 1 and a radiator 2, sent to the working chamber of the device, to which the testing sample 3 is placed. the weakened sound waves, transmitted through a sample of the fiber, is converted into an electrical signal by the microph one 4. the measuri ng unit 5 measures the mag

12、n itude of the sign al. i n block 6 the an alog signal converted into a coded output signal, which is shown on a digital display of unit 6.the output signal measured by unit 6 after passing through the sample connected with the parameters of the fiber by the ratio 1:；(1)；(2)where uo voltage at the m

13、icroph one in the abse nee of the sample, mv;a damping coefficient of acoustic waves, 1/m;l thickness of the fibrous mass, m;t - linear density, mtex;b - a constant factor;e porosity of the sample;f - frequency of sound vibrations, hz.lin ear den sity is conn ected with the micro naire index through

14、 a ratio3:；(3)from ratios (1), (2) and (3) we have the formula of functional conn ection of a signal on an exit of a microph one with a micronaire in dex for measuring fibrous material：(4)where(5)by logarithming the equation (4), we found(6)orwhere bo=ln uo.from the formula (7) we can see that linea

15、r regression relationship exists between a signal on an exit of a microphone at testing sample and micronaire index in logarithmic scale.this equation was used in the regression analysis in the construction of the instrument calibration graph.cotton samples of different varieties (108-f, s-6524, buk

16、hara-6, anbayaut 2, fergana3, yulduz), as well as standard samples of the physical and mechanical properties of cotton fiber were tested on an acoustic instrument to study the calibration dependenee of acoustic instrument from the micronaire index.tests were carried out by the following method. samp

17、les of cotton with weight of about 500 g passed through the cotton analyzer such as ah. then, four samples of weight on 10 g from each sample were collected and weighed in the balanee vlkt-500. in parallel, examples were selected from each sample and measurements were made on a system of hvi spinlab

18、-900 in terms of micronaire.then the sample is laid into the measuring chamber of acoustic instrument, and measurements of the output signal on the microphone at a fixed height of the measuring chamber were carried out. then the measurements repeated on other three samples. in four measurements for each sample the average value of the signal at the output of the microphone was calculated. further, on the basis of average values ?of measurements of the output and micronaire values, the linear regression equation under the formula (7), which connects the logarithm of the output signal from