SU913491A1 - Device for testing circular continuity of conductive coatings on dielectric fibers - Google Patents

Description

The invention relates to inspection of conductive coatings on dielectric fibers, in particular to control of the circular continuity of conductive coatings on dielectric fibers, and can be used for non-destructive testing of coatings of metallized glass fibers in the manufacturing process.

It is known that when applying coatings on the surface of a fiber, various defects ₍₁₎ are observed. One of them is the one-sidedness of the coating, characterized in that the coating covers the perimeter only by a certain angle less than 2tg. The identification of one-sidedness should usually be carried out against the background of such factors as the presence of gaps and isthmuses of the coating, sharp edges of the one-sided coating, changes in the angle of the one-sidedness of the coating, changes in the diameter of the fiber, designed to count the number _of surface defects conductive filaments and containing a recording device and a primary capacitive transducer, and for measuring defects of fibers' 2 and wires in the form of changes in diameter, including a recording device, an AC bridge, and a primary capacitive transducer C).

These devices have insufficient reliability of control, since high sensitivity to these background factors leads to an unacceptably low signal-to-noise ratio, which makes it difficult to identify the one-sidedness of the coating.

Closest to the proposed technical essence is a device for monitoring the circular continuity of conductive coatings on dielectric fibers, containing a primary corona discharge transducer with a sectioned electrode, a recording device and a switch commuting the output circuits of sections of the sectioned electrode with the inputs of the recording device. This device has additional electrodes mounted coaxially on both sides of the sectioned electrode, a rewind unit, and a power source. The device is designed to control the surface quality of microwires, but can also be used to control the circular continuity of conductive coatings on dielectric fibers [2].

The disadvantage of this device is that it does not provide reliable control of one-sided coverage, since the variation of the listed background factors over a wide range causes either corona transitions and flare and spark transitions, in which the projective correspondence of the distribution of the conductive coating on the fiber of the distribution of the discharge current over the primary electrode transducer, which leads to the inability to identify one-sidedness or to the destruction of the controlled fiber, or causes such changes in the current-voltage characteristic of the primary corona discharge transformation, in which the corona discharge either completely stops or becomes so intense that the projective correspondence of the distribution of the coating to the distribution of the discharge current on the electrode is weakened, reducing the reliability of the identification of one-sidedness at large coating angles (i.e., coverage angles coated fiber is larger than π).

The aim of the invention is to increase the reliability of control when changing the geometry of the coating, the presence of sharp edges of the one-sided coating and changes in the dielectric constant of the material of the fiber core.

This goal is achieved by the fact that in the device for monitoring the continuity of conductive coatings on dielectric fibers, containing a primary corona discharge converter, with sectional electrodes, a recording device and a switch 'switching the output circuits of the electrode sections to the input of the recording device, an additional stabilizer consisting of an adjustable source is introduced power supply, voltage measuring units and current measurements on a sectioned electrode of a primary corona discharge converter, generator a test signal generator and a calculation unit with three inputs, while the output of the regulated power source is connected to the input of the primary corona discharge converter and to the inputs of the current measurement and voltage measurement blocks on the electrode of the primary corona discharge converter, and the outputs of the current measurement and voltage measurement units are connected to the first and second the inputs of the computing unit, the output of which is connected to the input of an adjustable power source and the input of the trial generator? sinusoidal signal, the output of which is connected to the first input of the regulated power source and to the third input of the computing unit.

In addition, the calculation unit is made in the form of a narrow-band pass filter of double the frequency of the probe signal, narrow-band pass and trap filters of the frequency of the probe signal, three detectors, two dividing blocks, and a reading unit, and the inputs of the transmission filters are interconnected and are the first input of the block computing, the second input of which is the input of the blocking filter, and the output of the transmission filter of double the frequency of the probe signal is connected to the input of the first detector, the output of which is connected connected to the first input of the first division block, the output of the probe filter passing the frequency filter is connected to the input of the second detector, the output of which is connected _Μ to the first input of the second division block, the output of the blocking filter is connected to the first input of the subtraction block, the output of which is the output of the calculation block, the third input which is the input of the third detector, the output of which is connected to the second input of the first division unit, the output of which is connected to the second input of the second division unit, the output of which is connected to the second Odom subtractor.

In FIG. 1 shows a structural diagram of the proposed device: in FIG. 2 and 3 diagrams explaining the operation of the device.

The device contains a stabilizer 1, a primary corona discharge converter 2 with a sectioned electrode, a switching switch 3, a recording device 4.

The stabilizer 1 includes an adjustable 'power supply 5, a probe signal generator 6, a current measuring unit 7 on the electrode of the primary corona discharge converter, a voltage measuring unit 8, and a calculation unit 9.

The calculation unit 9 includes the first, second and third detectors 10-12, a pass filter ^{45 of the} doubled frequency of the test signal 13, a filter of the frequency of the test signal 14, the first and second blocks 15 and 16, the blocking filter 17 of the frequency of the test signal, block 18 subtraction ⁵⁰ The device operates as follows.

A voltage sufficient to corona the surface of the conductive coated ⁵⁵ controlled fiber is supplied from the stabilizer 1 to the electrode of the primary corona discharge converter 2. The distribution of the corona discharge current on the electrode is uniform with full circular coverage. When entering the primary converter 2 sections

9134 'fibers with discontinuous circular continuity, i.e. single-sided coating, the distribution of current on the electrode becomes uneven.

The corona discharge current is maximum at the electrode sections facing those sectors 5 of the fiber surface on which there is a conductive coating; current is minimal on sections facing uncoated sectors. An experimental example of the distribution of currents on an electrode with one side is shown in FIG. 2, where the following notation is accepted:

^_ “) 'Coefficient

Σ 1 _t M non-uniform - 15 times the distribution of the discharge current on the electrode;

I - current t-sec. 20 electrode

M is the number of sections of the electrode;

Θ - the angle measured from the middle of the 25th coating in. a polar coordinate system whose origin coincides with the center of the circumference of the cross section of the fiber core.

The electrode sections are connected alternately by a switching switch 3 to the input of the recording device 4, by means of which the distribution of the discharge current among the sections of the electrode is analyzed, and, for example, using the threshold device of the recording device 4, a signal is generated indicating the presence or absence of one-sided coverage.

The stabilizer 1 maintains a constant value of the ratio of the voltage across the electrode of the primary transducer 2 to the initial corona discharge voltage.

The stabilizer 1 operates as follows.

The voltage from the regulated power supply 5, supplied to the electrode of the primary corona discharge converter 2, is modulated by the probe signal generator 6 of a sinusoidal shape and has the form ’ϋ = .Ε + ν5ίηωί, (1) where E is the constant component of the voltage across the electrode;

V is the modulation amplitude of the probe signal;

6 ω is the circular frequency of the probe signal (for example, 10 kHz);

ί - time.

The current measuring unit 7 converts the current value of the primary disco transformer 2 into a signal e (1) = K ₆ 1, where K ₆ is the conversion coefficient of block 6;

I is the discharge current.

The conducted experimental studies revealed that the current-voltage characteristic of the corona discharge from a conductive coating on dielectric fibers is approximated with sufficient accuracy by the known quadratic dependence:

r, = di (u - and „), with u? 0 _and [1 = 0, for and <11c (2) where I is the corona discharge current;

A is a coefficient depending on the geometry of the electrode and the corona surface;

I and - voltage at the electrode;

and _n is the initial discharge voltage, depending on the geometry of the electrodes and the corona surface.

Due to the quadratic current-voltage characteristics and modulation of the voltage at the electrode, the signal at the output of current measuring unit 6 has the following form:

е (1) = К ₆ А [(Е ² - Е11 _н + Ϊ *) + + (2ЕУ - υ _Η ν) δϊηωΐ -) οοδ2ωΐ] (3)

It can be seen from expression (3) that in the output signal of block -6 there are components with both the frequency of the probe signal ω and the frequency 2ω.

ι

Voltage measurement unit. 8 on the electrode of the primary Converter 2 has an output signal proportional to the value I):

e (11) = K ₈ (E + νδΐηωί) (4) where K ₈ is the conversion coefficient of block 8.

Block 9 of the calculation determines the value of the current value of the initial voltage of 11 Hz current-voltage characteristics of the discharge, depending, as revealed by experimental and computational studies, on the fiber diameter, the angle of coverage of the core with a one-sided coating, the dielectric constant of the core material, as well as on the presence of gaps, isthmuses and sharp edges of one coverings.

With this on. the inputs of the calculation unit 9 and the signals e (1), e (11) arrive from the output of the probe signal generator 6, as can be seen from expressions (3) and (4), it is enough to calculate: the current value of the initial voltage ₅ , discharge.

When the current-voltage characteristics of the discharge change, a voltage proportional to _m is supplied from the output of the calculation unit 9 to the input of the controlled power source 5th and the input of the probe signal generator 6. As a result, the voltage at the output of the regulated power source 5 changes proportionally to CC, remaining in the optimal range values, for example, Ό = (1.1-1.2) 11 n +, 5 + (0.01-0.05) υ _Η 8ίηωί), in which corona discharge transitions are not observed. flare or spark, and slightly the influence of factors such as breaks, isthmuses, sharp edges of a one-sided coating on the formation of the distribution of the discharge current over the electrode of the primary corona discharge transducer 2.

Block 9 calculations works as follows. 25

A series-connected narrow-band pass filter 13 tuned to a frequency of 2sc and the first detector 10 separate the amplitude of a component with a frequency of 2ω from the signal e (1) received at the first input of the calculation unit 9; at the same time, from the output of the detector 10 to the second input of the first division block, a signal of the value υιο · = .Κιο K ₆ A is supplied, (5) 25 where K u is the transfer coefficient of blocks 13 and 10. '

A series-connected narrow-band pass filter 14 tuned to the frequency ω and the second detector 11 separate the amplitude of the component with frequency ω from the signal e (1) received at the first input of the calculation unit 9; at the same time, from the detector And output to the second input of the second division block 16, a signal is supplied with the value and „= к„ (2е - υ _Η ) νκ ₆ Α, (6) where К _1; - transmission coefficient of blocks 14 and 11. 50

The blocking filter 17 tuned to the 'frequency ω emits. from the signal and ₈ , supplied to the second input of the computing unit, the constant component; while the second input of the subtraction unit 18 receives a signal from the output ^{55 of the} filter 17

Mon ⁼ K17EK8, (7) where K, ₇ is the transmission coefficient of the filter 17.

The third input of block 9 of the calculations from the output of the probe signal generator 6 receives a signal in the form and ₆ = ί νδίηωί, (8) ^K 5. .

where K ₅ is the conversion coefficient of the test signal by block 5.

The signal and ₆ from the third input of subtraction block 9 is fed to the third detector 12, which extracts component K12 from it and, ₂ = -— ν, (9) to $ where K12 is the conversion coefficient of block 12, and feeds it to the first input of the first block 15 divisions.

In the first division unit 15, a signal is divided by the signal II ω entering its second input into a signal and n entering its first input. Given the expressions (5) and (9), at the output of block 15, the signal has the form _{C | 5} . . ^ UA (.O)

P "_Κϊχ. ν 2Κϊ2 • to ₅

The signal Ό15 is supplied to the first input of the second division block 16, where it is divided by the signal supplied to the second input of this block. As a result, at the output of block 16, taking into account expressions (6) and (10), the signal has the form c, '- C., - Κι, κ _<; Αν (2έ - and _{n) =} υι ₅ .κ.ι _η κ ₆ .Κ5 · _Ay.

2K, 2 ₌ 2K _n 1 $ q (2E _ and _n ). (eleven)

K10K5

The signal is supplied to the first input of the subtraction unit 18, where it is subtracted from the signal supplied to its second input. As a result, at the output of the block. 18, the signal has, taking into account expressions (7) and (I), the following form:

• 2K „K„ υιβ ~ Οιβ ~ Пп - КвКиЕ - КУК ₅ * χ2Ε-ϋ _Η ) (12)

With the appropriate choice of conversion coefficients of blocks 5, 8, 10, I, 17 and 12, determined by the ratio

MKiKp = Κ ₅ Κ ₈ ΚιοΚΐ7 „(13) signal II and has the form

Πιβ ~ 2Κ ₈ Κΐ7ΐΙ _Μ (14)

Thus, from the output of the subtraction unit 18 to the output of the calculation unit 9, a signal II 913491 is output that is proportional to the current value of the initial corona discharge voltage and serves to correct the voltage and (coming from the output of the stabilizer 1 to the electrode of the primary corona discharge * converter 2) during measurements parameters of the current-voltage characteristics of the discharge, four experimental examples of which are shown in FIG. 3 for the case of the absence of stabilization of the discharge mode with the help of the device being prepared. (shaded areas correspond to corona discharge transitions to the flare spark regimes).

The use of a device for controlling the circular continuity of conductive coatings 15 on dielectric fibers makes it possible to increase the reliability and reduce the complexity of controlling the quality of the coating of these fibers during their production and, as a result, organize optimal control _{of the} technological process, for example, the production of metallized glass fiber.

Claims (2)

The claims ₂ 5 1. A device for controlling the circular continuity of conductive coatings on dielectric fibers, comprising a primary corona discharge converter with a sectioned electrode, a recording device and a switch switching the output circuits of the sectioned electrode with the inputs of the recording device, characterized in that, in order to increase the reliability of control when changing the geometry coating, the presence of sharp edges of a one-sided coating and changes in the dielectric constant of the material of the fiber core, it will complement It will completely introduce a stabilizer consisting of an adjustable power source, voltage measuring and current measuring units on a sectioned electrode of the primary corona discharge transducer, a test signal generator and a calculation unit with three inputs, while the output of the regulated power supply is connected to the input of the primary corona discharge transducer and the inputs of the blocks for measuring current and measuring the voltage at the electrode of the primary co | conjugation connected to first and second inputs of the computing unit, an output of which is connected to the input of the regulated power supply and the input of the probe signal generator, the output of which is connected to the first input of the regulated power supply and to the third input of the computing unit. 2. The device’s by π. 1, the fact that the computation unit is made in the form of a narrow-band pass filter of the doubled frequency of the probe signal, narrow-band pass and block filters of the frequency of the probe signal, three detectors, two division blocks and a subtraction block, and the inputs of the pass filters are connected between and are the first input of the computation unit, the second input of which is the input of the blocking filter, and the output of the double-frequency transmission filter of the test signal is connected to the input of the first detector, the output of which The horn is connected to the first input of the first block. division, the output of the transmission filter of the frequency of the probe signal is connected to the input of the second detector, the output of which is connected to the first input of the second division unit, the output of the blocking filter is connected to the first input of the subtraction unit; whose output is the output of the calculation unit, the third input of which is the input of the third detector, the output of which is connected to the second input of the first division unit, • the output of which is connected to the second input of the second division unit, the output of which is connected to the second input of the subtraction unit.