RU1827618C - Apparatus for testing ferromagnetic articles - Google Patents

Abstract

The invention relates to non-destructive testing of parameters of ferromagnetic products using the Barkhausen effect and can be used in engineering enterprises. The purpose of the invention is to increase the accuracy of monitoring, due to the fact that the device for monitoring ferromagnetic products containing a series-connected generator, Barkhausen noise sensor, adder, amplifier, detector, integrator, synchronous detector and indicator, and the reference input of the synchronous detector through a series-connected frequency doubler , the phase shifter and the trigger are connected to the output of the generator, and also the second Barkhausen noise sensor is equipped with a phase-shifting unit, the output of which is connected to the output at the generator, and the output is to the input of the second Barkhausen noise sensor. The controlled and reference samples are remagnetized by magnetic fields shifted in time relative to each other so that the existence intervals of the Barkhausen EMF of the controlled and reference samples are separated by equal time intervals. These EMFs are summed and synchronously detected with a rectangular reference voltage of twice the magnetization reversal frequency. 2 ill. (L C

Description

The invention relates to non-destructive testing of parameters of ferromagnetic products using the Barkhausen effect and can be used in mechanical engineering.

The aim of the invention is to increase the accuracy of the control by providing relative measurements with automatic detuning from the influence of thermal and apparatus noise on the result of the control.

Figure 1 shows a block diagram of a device; figure 2 - timing diagrams of signal processing.

The device comprises a series-connected generator 1, a Barkhausen noise sensor 2, an adder 3, an amplifier 4, a detector 5, an integrator 6 and a synchronous detector 7, the output of which is connected to an indicator 8, and the reference input, through a series-connected frequency doubler 9, a phase shifter 10 and a trigger 11 - to the exit

00

go

x |

about

00

generator 1, as well as the second Barkhausen noise sensor 12, connected by an input through a phase-shifting unit 13 to the output of the generator 1, and by an output - to the second input of the adder 3.

Figure 2 shows: 14 - combined remagnetizing field strength and Barkhausen noise (controlled sample) of the sensor 2, 15 - combined remagnetizing field strength and Barkhausen noise (reference sample) of the 12.16-Barkhausen EMF sensor at the output of the integrator 6 (to is the signal of the controlled sample, e is the reference sample), 17 is the reference voltage from the output of the trigger 11.

The device operates as follows.

The current of the generator 1 feeds the magnetizing magnetization coil of the sensor 2, the field of which magnetizes the controlled product (not shown). Magnetization jumps occurring in each half-period of magnetization reversal are induced in the measuring winding of the Barkhausen EMF sensor 2 of the controlled sample (signals 14, Fig. 2). The current of the generator 1, through the phase-shifting unit 13, also feeds the magnetizing magnetization coil of the sensor 12, the field of which magnetizes the reference sample (not shown in the drawing), and the Barkhausen EMF of the reference sample is induced in the measuring coil of the sensor 12 (signals 15, Fig. 2). In this case, the phase of the field remagnetizing sensor 12 is shifted with the help of the phase shifting unit 13 so as to separate the pulse packets of the Barkhausen EMF of the controlled and reference samples at equal time intervals. From the outputs of sensors 2 and 12, the time-separated sequences of pulse packets of the Barkhausen EMF of the controlled and reference samples are fed to the inputs of the adder 3, the output signal of which is amplified by a selective amplifier 4, is detected by a detector 5 and integrated by an integrator 6 with a constant time.

providing the formation of the envelope of the current spectrum 16, figure 2, at the output of the integrator 6. This sequence of detected packets of pulses of EMF

Barkhausen controlled and reference samples, alternating in time, from the output of the integrator 6 is fed to the input of the synchronous detector 7, and to its reference input from the output of the generator 1, through a series-connected frequency doubler 9. the phase shifter 10 and trigger 11 are doubled in frequency and shifted in phase voltage 17, Fig. 2, of a rectangular shape so that overlapping signal areas from the output of the integrator of the bis output of trigger 11 are observed (signals 16.17, Fig. 2). From the output of the synchronous detector 7, a signal proportional to the difference between the values of the Barkhausen EMF of the controlled and the reference

samples, served on indicator 8, according to the indications of which the results of control are judged.

Due to the introduction of new units and their functional connections, the device eliminates the influence on the result of monitoring thermal and apparatus noise both from the signal of the monitored and from the signal of the reference samples.

Claims (1)

The claims A device for monitoring ferromagnetic products, comprising a series-connected generator, a Barkhausen noise sensor, an adder, an amplifier, a detector, an integrator, a synchronous detector, the reference input of which is connected to the generator output through a frequency doubler, a phase shifter and a trigger, and an indicator, as well as a second Barkhausen noise sensor connected by an output to the adder input, characterized in that, in order to increase the control accuracy, it is equipped with a phase-shifting unit, the input of which is connected to generator output, and the output to the input of the second Barkhausen noise sensor. P 75 17 .2