SU1422135A1 - Method of checking the quality of ferromagnetic articles - Google Patents

Abstract

The invention relates to non-destructive testing and can be used to control the continuity of stretched ferromagnetic thin-walled shells of rotation by acoustic emission signals. The aim of the invention is to increase the reliability of control by reducing the level of interference and eliminating the possibility of damage to the surface of the shell. The method consists in loading the product with an increasing load from zero and additionally scanning it with a constant magnetic field, thereby eliminating the simultaneous action of several sources of acoustic emission signals caused by surface damage and reducing the level of interference. 1 il. (L

Description

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The invention relates to non-destructive; control of the loaded structures and can be used to control the continuity of the stretched ferromagnetic thin-walled shells of rotation by acoustic emission signals.

The aim of the invention is to increase the reliability of control of thin-walled stretched shells in the form of a rotary body by reducing the level of interference and eliminating the possibility of damage to the surface of the shell.

The drawing schematically shows a device that implements the method of quality control of ferromagnetic products,

As a product 1, a thin-walled casing is used, for example, an expanded membrane, which is installed in a loading cell 2 and pressed against it with a holding ring 3. The pressure P in loading cell 2 is created using a pressure source (not shown). Additional local loading q is created by an electromagnet 4. The magnetic force is established using source 5. In addition, the device uses a serially connected transducer 6, a preamplifier 7, an analyzer 8 acoustic signals, and a registrar 9 (recorder).

The method of quality control of ferromagnetic products is carried out as follows.

In the cell 2, from the side of the concave surface of the shell 1, a test pressure P is fed, monotonously increasing from zero values. At the same time, the local surface loading load of a constant value (0.3-095) E () 2, where E is the modulus of elasticity, is applied to the spinning surface of the shell 1 using an electromagnet 4.

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h is the shell thickness; R is the minimum radius of its curvature, and the surface of shell 1 is scanned by it. As a result of a magnetic field, an elastic bending of the shell takes place on a section with a diameter of (5-7) h Rh. check, losing stability in the elastic stage of work. The simultaneous action of two types of loads P and q with a constant increase in the main load P

leads to the appearance of a complex stress-strain state on a controlled part of the surface, which corresponds to the maximum permissible load on the shell.

With further growth of the main test load P, the total stresses on the shell 1 and in the area of application of the scanning load q are

(0.3-0.5) E (-) 2 increase until the initial phases of plastic deformation of the material begin to develop, which is accompanied by the appearance of acoustic emission signals. The acoustic emission signals are received by the transducer 6, amplified by the preamplifier 7, processed by the analyzer 8 acoustic signals.

In the case of a practically defect-free shell 1, the motion of the scanning load q causes continuous emission of the acoustic emission signal. If the thickness of shell 1 contains a stress concentrator in the form of a closed crack or other types of discontinuity, the occurrence of acoustic activity is primarily detected by a recorder as the load q passes over this defect. In this case, when the load q passes over the weakening region, the primary development of the initial phases of the plastic flow occurs, which manifests as a peak in the intensity of the acoustic emission signals.

Based on the position of the load q at the moment of maximum intensity of the acoustic emission signals, the location of the defect is determined. Due to the choice of the load q

(0.3-0.5) E (-) acoustic active

This is manifested exactly at the place of application of the load, which increases the reliability of the location. Due to the fact that the local buoyancy load q is carried out by scanning the surface of the shell with a magnetic field, the possibility of its damage is excluded, causing the simultaneous occurrence of several sources of acoustic emission and an increase in the level of interference.

Thus, when using the quality control method of ferromagnetic products, the level of

electromagnetic interference and the likelihood of damage to the product, which increases the reliability of control of the stretched shells in the form of a body of revolution.

Claims (1)

Invention Formula about The method of quality control of ferromagnetic products by acoustic emission signals, which consist in loading the product with increasing load and additional local load from zero, register the parameters of acoustic emission signals, according to which they are characterized in that, in order to increase the reliability of monitoring thin-walled stretched shells in the form of a body of rotation, the additional load is carried out by scanning the product with a magnetic field, and the magnitude of the load q is chosen from the ratio q (0.3-0.5) E (|) S where E is the modulus of elasticity; h is the shell thickness; R is the minimum radius of curvature of the shell.