SU1698731A1 - Device for nondestructive sophisticated check of ferromagnetic products - Google Patents

Abstract

The invention relates to magnetic non-destructive testing of ferromagnetic products and can be used to control the structure of iron and steel products. The purpose of the invention is to increase the sensitivity and performance by reducing the measurement error of the magnetic and acoustic characteristics of products and increasing the efficiency of the control. At the command of the computing unit 4 from the electromagnetic field generator 1, current pulses of a certain (small) amplitude are supplied to the magnetization windings, under the influence of which the controlled section of the product is re-magnetized along a hysteresis loop of the private magnetization cycle. At the moments when the EMF of the magnetic converter 7 becomes equal to zero, the demagnetization current of the reference electromagnet is measured, which is a measure of the coercive force of the material of the product. After 10-12 cycles of magnetization reversal, the computing unit calculates the average value of the demagnetization current on the partial cycle 1p1. Then, at the command of the computing unit 4 from the generator 1, powerful current pulses are supplied to the magnetization winding, under the influence of which the product is re-magnetized along the hysteresis loop of the limiting cycle, at which the technical saturation of the product material is achieved. Similarly to the previous one, the average value of the demagnetization current P2 is measured at the limiting magnetization cycle. Further, at the command of the computing unit 4, the propagation velocity of the ultrasonic vibrations is measured. The measured values of the demagnetization currents and the speed of the ultrasonic vibrations are used to calculate the values of the mechanical parameters. 1 il. С / С о а ЧА

Description

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The invention relates to magnetic non-destructive testing of ferromagnetic products and can be used in literary and thermal-logging workshops of machine-building enterprises in controlling the structure of iron and steel products.

The purpose of the invention is to increase the sensitivity and performance by reducing the measurement error of the magnetic and acoustic characteristics of products and increasing the efficiency of the control.

The drawing shows the block diagram of the device.

The device contains an electromagnetic field generator 1, a transducer unit 2 connected in series, a signal processing unit 3 and a computing unit A (microprocessor K 580BM80A). The first of the control outputs of the computing unit 4 is connected to the input of the generator 1, and the information output is connected to the information output unit 5, the device also contains an acoustic field generator 6, the output of which is connected to one of the inputs of the converter unit 2

The transducer unit 2 comprises a magnetic transducer 7, made, for example, in the form of an attached electromagnet with a flux-gate transducer, and an acoustic transducer 8, made in the form of a separately-combined transducer. Acoustic transducer

8 is placed between the poles of an attached electromagnet.

The signal processing unit 3 contains a subunit 9 for measuring the demagnetization current of an attached electromagnet in the partial and limit cycles of magnetization reversal and a subunit 10 for measuring the velocity of longitudinal acoustic oscillations. Subblocks 9 and 10 are connected to converters 7 and 8, respectively. Control inputs of subblocks

9 and 10 are connected to the third and fourth control outputs of the computing unit 4, the second control output of which is connected to the generator b of the acoustic field. The outputs of the subblocks 9 and 10 are connected to the inputs of the microprocessor 4.

The device works as follows.

When the device is started up, the computing unit 4 processes the multi-parameter measurement information supplied to its informational inputs from the degaussing current measurement subunit 9 in partial and limit cycles and the acoustic vibration subunit 10. The algorithm of operation of the computing unit 4 provides for two modes of control and processing of measurement information.

In the control mode, the computing unit 4 issues commands to the control input of the generator 1 of the electromagnetic field, along which the latter sequentially supplies current pulses to the magnetizing coil of the magnetic converter 7. To the control signals of the computing drive

Block 0 sets the magnitude and direction of the current pulses of the electromagnetic field generator 1. The control input of the subunit 9 is commanded to start measuring the demagnetization current on the private and marginal

5 cycles of magnetization. The obtained demagnetization current proportional to the coercive force (Hc) is digitally fed from the output of the subunit 9 to the information input of the computational

0 of block 4 and stored in its registers, then the computing block 4 turns on the generator 6 of the acoustic field. Its probe pulses excite the piezoelectric acoustic transducer 8, which

5 emits ultrasound waves into a controlled object. The speed of propagation of ultrasonic longitudinal-surface (head) waves is determined by the speed hub unit, to the control input of which synchronizing pulses are received from the computing unit 4. The output of the subunit 10 digitally stored in registers

5 computing unit 4,

In the processing mode of the measurement information, the computing unit 4 processes the values of the coercive force Not in the registers on the partial and limit magnetization cycles and the propagation speed of the ultrasonic oscillations according to the experimentally established mathematical regression model, at which the coefficient of multiple correlation between the values of the signals from the transducers 7 and 8 and controlled physical and mechanical characteristics of the controlled product has the maximum value.

0 Approximate parabola the relationship between hardness and demagnetization current on a private cycle, write

H eailjh + bilp1 + ci, (1)

where H is hardness;

ai, bi. ci are the approximation coefficients determined from experimental data on a batch of samples.

On the limit cycle

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H 82lpi + 02lp2 + C2,

(2)

Multiplying equation (1) by aa / ai and subtracting equation (2) from it, we get

H A - 1P1 + C (3)

Where

92 bi .0 aib2 .c (ci -C2) -ai 32 -ai 32 -ai

From expression (3) it can be seen that the transformed dependence between hardness and demagnetization currents on the particular and limiting cycles is linear,

From the output of the computing unit 4, the result of the calculation is fed to the input of the information output unit 5 and is displayed on the information board.

Thus, connecting in the device of the subunit measurement of magnetic and acoustic parameters to the inputs of the computing unit, by computationally processing the output signals of the subunit, reduces the measurement error of the magnetic and acoustic characteristics of the products and increases the control efficiency.

Claims (1)

An apparatus for multi-parameter non-destructive testing of ferromagnetic products, comprising an electromagnetic field generator, a magnetic transducer connected to it, an acoustic field generator, an acoustic transducer connected to it, a signal processing unit and an information output unit, in order to increase sensitivity and performance it is equipped with a computing unit, two control outputs of which connected to the inputs of the electromagnetic field generator and the acoustic field generator, respectively, and the information output is connected to the information output unit; the magnetic transducer is designed as an attached electromagnet, an acoustic transducer is placed between its poles, and the signal processing unit is made in the form of sub-blocks, respectively, measuring the demagnetization current of the attached electromagnet on the partial and limit reversal magnetization cycles and measuring the speed of acoustic oscillations, the inputs connected respectively to magnetic and acoustic transducers, and outputs information inputs of the computing unit, and control inputs, respectively, with the third and fourth output E computing unit.