SU905771A1 - Device for checking flaws in ferromagnetic articles - Google Patents

Description

I

The invention relates to instrumentation engineering and can be used for flaw detection of products and parts made of ferromagnetic materials.

A device for controlling ferromagnetic materials is known, which contains a magnetostriction plate and a magnetization device for a controlled article tl.

A disadvantage of this device is the low stability of the control results.

The closest in technical essence to the invention is a device for monitoring defects in ferromagnetic products, comprising a generator, an electromagnetic-acoustic converter coil connected to its output, a magnetizing system located above the coil, a magnetostrictive plate placed under the coil, an amplifier connected by an input to coil pins;

and an indicator connected to the output of the amplifier. The device provides high stability of control results 2 J.

However, for this device, there is a characteristic lack of sensitivity and noise immunity.

The purpose of the invention is to increase the sensitivity and noise immunity and to ensure that

to the size of the defect.

This goal is achieved by the fact that the plate is made in the form of a disk, and the cuticle is made in the form of a flat helix coaxially with the disk.

15

In addition, the magnetizing system is made in the form of a cylindrical magnet magnetized along the axis, which increases the reliability of the control by detecting defects of various types.

20 orientation.

The device is also equipped with a pulse counter, the input of which is connected to the output of the amplifier.

In addition, the device is equipped with a unit comparing the amplitudes of adjacent echo pulses in a plate connected by its input to the output of the amplifier.

The drawing shows a diagram of the device.

The device consists of a magnetizing system 1, located when operating near product 2, a magnetostriction plate 3, a coil k of an electromagnetic-acoustic transducer, the system 1 being fixed above coil 4, and a plate 3 by coil C. In addition, the device contains a generator 5, the output of which with a coil, the amplifier 6 whose input is also connected to the terminals of the coil k, and an indicator 7 connected to the output of the amplifier 6, a pulse counter 8, a block 9 comparing the amplitudes of adjacent echo pulses in the plate 3.

The device works as follows.

The oscillator 5 s psio transducer excites in plate 3 in the presence of a defect ultrasonic vibrations, which spread, are reflected repeatedly from the edges of the disk and are recorded by the transducer, amplified by amplifier 6 and fed to indicator 7, counter 8 and amplitude comparison unit 9. An increase in sensitivity and noise immunity is achieved due to the fact that the spiral flat coil k excites ultrasonic oscillations in disk 3, which propagate in all directions along the radii and repeatedly reflecting from the edges of disk 3. The choice of the shape of the 3-in-form disk will result in its center of waves propagating in different directions, which significantly weakens the effect of the orientation of the defect. Since the number of multiple echo pulses is proportional to the size of the defect, their number, calculated using counter 8, determines the size of the defect. When multiple reflections arrive at the amplitude comparison unit 9, the relative magnitude of the adjacent echo pulses in plate 3 is estimated. This value is determined by the attenuation of acoustic waves in the material of the disk 3. The magnitude of this attenuation is known or may in advance

be determined. Therefore, the relative decrease in the amplitudes of ultrasound, which are known in advance and entered into the amplitude comparison block 9, is compared in block 9 with the measured relative value, from which it becomes possible to separate the useful signals from interference, i.e., an additional increase in noise immunity.

Claims (4)

Invention Formula t. A device for monitoring defects in ferromagnetic products, comprising a generator, an electromagnetic transducer coil connected to its output, a magnetizing system located above the coil, a magnetostrictive plate placed under the coil, an amplifier connected to the coil terminals, and an indicator connected to the amplifier output, This is due to the fact that, in order to increase the sensitivity and noise immunity, the plate is made in the form of a disk, and the coil - in the form of a flat helix coaxial with the disk. 2. An arrangement according to claim 1, which is to say that, in order to increase the reliability of the control by detecting defects of various orientation, the magnetizing system is made in the form of a cylindrical magnet magnetized along the axis. 3. The device according to paragraphs. 1 and 2, about the fact that, with In order to make it possible to determine the size of the defect, it is equipped with a pulse counter, the input of which is connected to the output of the amplifier. 4. Device on PP. 1 - 3, about the fact that it provided with a unit comparing the amplitudes of adjacent echo pulses in a plate connected by its input to the output of the amplifier. Information sources, taken into account in the examination 1. USSR author's certificate in application K 2530535 / 25-28, cl. G 01 M 29/0, 1977. 2. The author’s reference of the USSR for application number 2490687 / 25-28, cl. G 01 N 29/04, 1977 (prototype)