SU1226271A1 - Apparatus for inspection of ferromagnetic articles - Google Patents

Description

I

The invention relates to non-destructive testing of the parameters of ferromagnetic products by the magnetic-noise method and can be used in enterprises of machine-building and instrument-making industries.

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

FIG. 1 is a block diagram of a device for controlling ferromagnetic products; FIG. 2 - signal plots at control points.

The device contains a series-connected generator 1 with a controlled amplitude of oscillations, a Barkhausen noise sensor 2, an amplifier 3, a detector 4, an integrator 5, a threshold unit 6, a clock generator 7, and a pulse counter 8. The device also contains an automatic extremum search unit 9 consisting of a differentiation unit 10 connected in series, the input of which is connected to the integrator 5, and a zero-organ 11, the outputs of which are connected to the control inputs of the generator 1 with controlled oscillation amplitude and the clock generator 7; Pmpuls

The device works as follows.

At the command of Starting, a generator 1 with a controlled amplitude of oscillations begins to feed a reversing magnetizing coil (not shown) of the Barkhausen noise sensor 2 with a low frequency current with a linearly increasing oscillation amplitude. The Barkhausen emf is recorded by a measuring coil (not shown), amplified by a 3, detected by a detector 4 and integrated by integrator 5 with a constant time t T, where T is the period of the magnetization reversal, From the output of the integrator 5, a signal proportional to the spectral density Barkgauzep noise, p steps on the input of the threshold unit. 6 with a threshold determined by the voltage of thermal and instrumental noise acting at the output of the Barkhausen EMF gain path (at the output of the integrator 5). When a signal is generated by the EMF of Barkhausen, the threshold block B starts up and the generator 7 clocks are triggered. at the output of which the voltage VTU () of FIG. 2 takes effect in the form of clock pulses with a constant amplitude and frequency

- t

the following f, where is the frequency of the magnetizing field.

From the output of the integrator 5, the signal also goes to the input of the automatic extremum search unit 9, t, e, to the differentiation unit 10, from the output of which the signal proportional to the rate of increase of the noise power spectral density of Bark (j Hausen (13, fig 2) enters the input of the zero-organ 11, which stops the generation of the generator 7 pulses of pulses at the moment of reaching the maximum value of the spectral

 The noise power of Barkhausen (point A on curves 12 and 13, fig. 2) At the same time, the signal from the null organ 11 goes to the control input of generator 1 and the amplitude of its oscillation starts to decrease to zero, at which the device is ready for a new measurement cycle.

Thus, the pulse counter 8 records the clock pulses (14, Fig. 2), the number of which is determined by the interval of values of the intensity of the magnetization reversal field corresponding to the beginning of the occurrence

 The Barkhausen emf in the test sample and the extremum of the function U f (H), Based on the pulse counter reading and judging the results of the control,

35 Forms of invention

A device for monitoring ferromagnetic products containing a series-connected oscillator with a controlled amplitude of oscillations, a Barkhausen noise sensor, an amplifier, a detector, an integrator, and an automatic extremum search unit consisting of series-connected. a differentiation unit and a null organ, the output of which is connected to a control input of a generator with a controlled amplitude, and a threshold block connected to the output of an integrator, characterized in that, in order to increase the control accuracy, it is equipped with a series-connected clock generator The input input of which is connected to the output of the null organ, and a pulse counter connected to the output of the threshold unit.

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Launch

 Start

1

Editor I. Derbak

Compiled by Y. Glazkov Tehred I. Veres

Order 2121/39 Circulation 778 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d, 4/5

Production and printing company, Uzhgorod, Project 1a, 4

Fyg.2

Corrector S.Cherni

Claims (1)

A device for monitoring ferromagnetic products, containing a series-connected generator with a controlled amplitude of ⁴⁰ oscillations, a Barkhausen noise sensor, an amplifier, a detector, an integrator, and an automatic extremum search unit consisting of series-connected ones. ⁴ ^ differentiation unit and a zero-organ, the output of which is connected to the control input of the generator with a controlled amplitude, and a threshold block connected to the output of the integrator, ⁵⁰ characterized in that, in order to increase the accuracy of control, it is equipped with a series-connected clock generator controlling whose input under ⁵⁵ keys to the output of the zero-organ, and a pulse counter connected to the output of the threshold block.