SU1379717A1 - Device for eddy current inspection - Google Patents

Abstract

This invention relates to the field of non-destructive testing of metal products by the eddy current method. The aim of the invention is to improve the accuracy of the control. Higher harmonics are present in the output signal of frequency converter 5. This voltage is fed to the inputs of synchronous detectors 6 and 10, the outputs of which have the constant components of the signal arriving at the first inputs of the key elements 7, 11, the second inputs of which receive the voltage from the outputs of controlled sources 13, 14 wives The output voltages of the key elements 7, 11 are generated as a result of switching the input voltages, and they can be considered as the sum of two sequences of pulses shifted by T / 2 with an amplitude of pulses defined by the level of the input voltages, where T is the switching period. The band-pass filters 8, 12 allocate the constant components of the output signals of the elements 7, 11, which are due to the residual unbalance of the vortex converter. By adjusting the voltage of sources 13 and 14, compensating for this voltage is sought. 2 Il. with S (L

Description

with so

flash

The invention relates to the region on the windings of the ECP 3 excitation.

non-destructive metallic-amplified preamplifier

By the Bikhretok method and 4, the output voltage of the VTP 3 can be used in machine building at the input of a frequency converter 5.

ten

and

eat

and

"about

20

and

Wo, tfio. Part 30

Research institutes and other areas of equipment for the purpose of flaw detection

The purpose of the invention is to improve the accuracy of control due to voltage compensation due to residual unbalance of eddy current transducer (VTP)

Fig. 1 shows a functional diagram of the proposed device in Fig. 2, voltage diagrams that show the operation of the device.

The device contains a series-connected oscillator 1, power amplifier 2, VTP 3, preamplifier 4, frequency converter 5, first synchronous detector 6, first key element 7, first band-pass filter 8, indicator 9, a torus 9 connected in series

 the second synchronous detector 10, the second 25 / °, „°,), the key element 11, the second band-pass filter 12, connected by its output to the second input of the indicator 9. The input of the second synchronous detector is connected to the output of the frequency converter 5. The device also contains two adjustable sources 13 and 14 of constant voltage, the output of the first source 13 is connected to the second pbtM input of the first key element 7, and the output of the second source 14 is connected to the second input of the second key element 11, serially connected to the first phase shifter 15, the first the balance modulator 16 and the adder 17, connected in series to the second phase shifter 18, the second balanced modulator 19, the output of which is connected to the second input of the adder 17. The device also contains a reference generator 20, the output of which is with the input of the second phase shifter 18, to a second input of the first balanced modulator 16, and controls kschimi- inputs of the second synchronous detector 10 and the second key element 11. In this case the control inputs of the first synchronous detector 6 and the first key member 7 connected to the output of the second phase shifter 18.

A control voltage supplied to the second input of frequency converter 5 is formed in a channel including reference generator 20, phase shifter 15 and 18, balanced modulators 16 and 19, and adder 17. Phase shifters 15 and 18 serve to form a 1/2 phase shift on the frequencies of the master and reference oscillators 1 and 20.

If the output voltage of the master oscillator 1

co8 ((J, t-bq, o).

and the output voltage of the reference generator 20 is equal to

and. cos ()

amplitudes, frequencies, and initial phases of generator voltages 1 and 20,

then in the output voltage spectrum of the first balanced modulator 16 the following components:

and

35

s

b

-and

etxx

15

and

and oh uo

you 10

40

| -in1p (f. - Oo) t-Kf, o-Cfo - “- sin (o, h-CO,) t-Kf,,

.45

where is the output voltage of the phase shifter 15.

Accordingly, the spectrum of the second balancing modulator 19 contains components

etXKiq

OUT, 8

50

(co.-cOo) t + q ,, -Cfj -bsin (ω, + C0o) t + q, ifc.

The output voltage of the adder 17, formed as the sum of the output eg ,, ..., h -.ipk-d-- -. balanced modulators 16 and 19,

The device works as follows.

equally

and

and.

C p

and oh uo

one

The voltage of the master oscillator is fed through the amplifier 2 to the input power of the frequency converter 5.

A control voltage supplied to the second input of frequency converter 5 is formed in a channel including reference generator 20, phase shifter 15 and 18, balanced modulators 16 and 19, and adder 17. Phase shifters 15 and 18 serve to form a 1/2 phase shift on the frequencies of the master and reference oscillators 1 and 20.

If the output voltage of the master oscillator 1

and

"about

co8 ((J, t-bq, o).

20

and the output voltage of the reference generator 20 is equal to

and

and. cos ()

Wo, tfio. Part 30

 25 / °, „°,)

amplitudes, frequencies, and initial phases of generator voltages 1 and 20,

then in the output voltage spectrum of the first balanced modulator 16 the following components:

/ °, „°,),

and

s

b

-and

etxx

15

and

and oh uo

you 10

 25 / °, „°,)

40

| -in1p (f. - Oo) t-Kf, o-Cfo - “- sin (o, h-CO,) t-Kf,,

.45

where is the output voltage of the phase shifter 15.

Accordingly, the spectrum of the second balancing modulator 19 contains components

 25 / °, „°,)

etXKiq

OUT, 8

50

-cOo) t + q ,, -Cfj -bsin ifc.

equally

and

(s,

and.

C p

6S) P9

sin (Q, + cojt + q, o +.

and oh uo

honor

3 13797174

This voltage is used in cdt-ii o / -.), N Г

flbl -, -OSV-f, /, TG

tve reference for converter. L 2

5 frequencies. If the enhanced pre-2 chg-sin (n to ,, t)

telny amplifier 4 output eg with 2.- п J

VTP 3 is equal to g. and-:. h

ITGTCH TT-1 2 SlnCnCJot)

I Bbot Ugb, 2 1g 2- ;;

b. (0,), L n, ... S J

TO in the output voltage of the transducer tO In this case, the sum signal at frequency selector 5 is present following the first key element 7: it has the following components:

Calc.) U, oUo and ,, (Z) U ,,. ,, (1) + and ,, „(2) .sin (U. -Ko,) t + Q .., - btf, U.cos (cp, o-Cj,) -and iv ..,

K, and. sin (co.t-C, .. c, ... c,) .. with (r „-sr,) - and

H-sin (20. -bojt4- (|), + q), o + q) | ,

-hto V ° oClick bandpass filter 8 perlAt; L- ./ t

 Vuyu harmonica (, we get

This voltage is applied to the input.

of the first synchronous detector 6, 25 and 1, J whose control input receives the output voltage of the second phase voltage;

to sin Ufl L

Shatel 18. In this case, the output of the first

synchronous detector from the spectrum of the value of U | COs (cf, -Cf,) determines

J. the fixed component, due to

Ugj ,, I cos (tf, 3 -cf |) -cos (2 too t - by residual H (imbalance of ECP 3. Regulator,, you can achieve, ,,. О N / o,. X sensation of this voltage. s, .. + 2q),) (2Q, t + CP ... + to,) -.

 ° o Similarly, the output voltage

Г / „„ h, о п1 of the band-pass filter 12 -cos I (2со,) „) t + Cf. + tf, o + 2cf J, 35

2G. the constant component would be and - -.

vb, .b „osg (fo-4.) - UebU.J COS COO t.

40

The constant component of U sin (cf - and is fed to the input of the first key., Due to the residual non-element 7.-Fri-tt

VTP 3 balance is compensated by the output voltage of source 14. At

„Ks ... with a change in the output voltage of the VTP 3

Accept - 1, which does not affect 2 changes and the output voltage

qualitative results. On the second band filters 8 and 12, the character of the key element 7 comes to a change, and ,,,

the output voltage of source 13 across these voltages is fed into the voltage indicator. Output eg - - 9, in which the module and

The first key element is the 7 phase of the useful signal. formed by switching

Claims (1)

input voltages, it is possible to view the formula of the invention as the sum of two sequences of pulses shifted by a device for eddy current control, containing sequentially - ;: With an amplitude of imguls, defined 2, .- f-, connected by a master oscillator, amplified by the level of the input voltages, where the power amplifier, the eddy current predominant T - the switching period, the distributor, the preamplifier and a frequency converter connected in series the first phase shifter, whose input is connected to the output of the master oscillator, the first balanced modulator and the adder, serially connected reference oscillator, the second phase shifter and the second balanced modulator, the second input of which is connected to the output of the master oscillator and its the output is connected to the second input of the adder, the output of which is connected to the second input of the frequency converter, and the second input of the first balanced modulator is connected to the output of the reference oscillator, which is different by that. % rW in order to increase the control accuracy, it is equipped with two synchronous detectors, the first inputs of which are connected to the output of the frequency converter, two bandpass filters, the inputs of which are connected to the outputs of the detectors through key elements, and their outputs - to the indicator, and two adjustable DC sources The outputs of which are connected respectively to the second inputs of the key elements, the control inputs of which and the second inputs of the synchronous detectors are connected respectively to the outputs of the first phase shifter and reference generator.