SU1748031A1 - Method and device for determining mechanical properties of articles of ferromagnetic materials - Google Patents

Abstract

The invention relates to the non-destructive testing of articles made of ferromagnetic materials and is intended for use in the control of heat treatment and the determination of the mechanical properties of ferromagnetic products in various industries. The aim of the invention is to improve the accuracy by adjusting the effect of the gap. The gradients of the intensity of the residual magnetization field are measured at two different distances from the surface of the product under test, the magnitude of the intensity gradient of the field of residual magnetization on the surface of the product under test is determined by them and the mechanical properties are judged by it. The implementation is provided by the converter 1, the magnetically sensitive elements 2, 3 and the reference sources 4, 5 of the magnetic field, the solenoid 6, the switching unit 7, the measuring unit 8, the keys 9, 10, 11, 12, the integrators 13 , 14, synchronization unit 15, blocks 16, 17, memory, computation unit 18, indicator 19 and magnetization unit 20, 2 sec. f-ly, 1 ill.

Description

The invention relates to non-destructive testing of products made of ferromagnetic materials and is intended for use in the control of thermal processing and the determination of the mechanical properties of ferromagnetic products in various industries.

It is known that especially the definitions of mechanical properties of products from ferromagnetic

materials, in which the product is magnetized by a series of pulses of an axially symmetric magnetic field of increasing and then decreasing amplitude, and read the gradient of the residual local field along the axis of symmetry.

A device that implements this method contains a magnetization unit, a transducer placed in it magnetochovst ™ l

element, measuring unit, comparison circuit and pulse amplitude meter,

The closest to the invention to the technical essence is a method for determining the mechanical properties of products made of ferromagnetic materials, in which a controlled product is magnetized with a series of pulses of increasing and then decreasing amplitude, the residual magnetization field gradient is measured along the axis of symmetry, and the residual local field gradient is additionally measured the axis of symmetry at a given distance along the axis of symmetry and take into account the change in the gradient when determining the mechanical properties of products.

A device that implements this method contains a magnetizing unit connected in series, a transducer, located in it two magnets for sensory elements, the outputs of which are connected to the inputs of the first and second blocks of / vision, the outputs of which are connected to the inputs of the switching unit, the first output of which is connected to connected to the first peak detector, the squaring unit, the dividers and the indicator, and the second output of the switching unit is connected to the series-connected filter of the second peak the detector, the output of which is connected to the second input of the division unit.

The disadvantage of this method and device is the small area of the clearance from the effect of the gap and the insufficient accuracy of determining the mechanical properties of ferromagnetic products,

The aim of the invention is to improve the accuracy by adjusting the effect of the gap.

This goal is achieved by the fact that in the method for determining the mechanical properties of products made of ferromagnetic materials, namely, that the product is magnetized by an axially symmetric magnetic field, the change in the voltage gradient of the residual magnetization field is measured, by which the mechanical properties of the products are measured, the measurement of the change the gradient of the field strength of the residual magnetization is carried out by a compensation method at two fixed distances from the surface of the products, and the gradient of the stress is calculated ti floor residual magnetization on the surface of the article which is used in determining the mechanical properties of the products.

The goal is achieved by the fact that the device for determining the mechanical properties of products made of ferromagnetic materials, contains a block

magnetizing, the input connected to it is a solenoid with two two MKhtsevostostvuyuschie elements located at a given distance from its working end, the switching unit, the measuring unit and, therefore, the connected computing unit and the indicator, are equipped with two chains, each of which is made in the form of serially connected the first key whose input is connected to the output

5 Btox measurements, an integrator, a second key, a reference source of a magnetic field and a memory unit, and a synchronization unit, the first output of which is connected to the control inputs of the switching unit and the keys, the second and third outputs are connected through one of the memory blocks to the corresponding inputs computing unit, and the reference magnetic field sources are installed inside the solenoid coaxially on

5 equal to the distance from the magnetically sensitive elements, the outputs of which are connected through the switching unit to the input of the unit,

The drawing shows a structural

0 device diagram.

The method includes the following sequence of operations;

the controlled product is magnetized by an axially symmetric magnetic

0 ass

change the intensity gradients of the residual magnetization field at two distances from the surface of the test product along the axis of symmetry,

0ROM calculates the gradient of the intensity of the residual magnetization field on the surface of the test product, according to which the mechanical properties of the product are judged.

5 The operation of the method is carried out on the example of operation of the device.

The device contains a converter

I, magnetosensitive elements 2, 3 located in it, and reference sources 4, 5 magnetic field, solenoid 6, switching unit 7, measuring unit 8, keys 9, 10,

II, 12, integrators 13, 14, synchronization block 15, memory blocks 16, 17, calculation block 18, indicator 19 and block 20

5 magnetizing.

A device for implementing the method works as follows.

After turning on the power and installing the converter on the surface of the test product, the magnetizing unit 20 is turned on. The controlled product is magnetized using a solenoid b located in the transducer. At the output of the magnetically sensitive elements 2 and 3, an output signal appears, which is fed to the inputs of the switching unit 7. From the output of the switching unit 7, the signals arrive at the input of the measurement unit 8 and then to the inputs of the keys 9 and 11. The synchronization unit 15 controls the operation of the switching unit 7 and the keys 9, 10, 11, 12 in such a way that when using 7 the first magnetosensitive element 2 is connected to the measurement unit 8, the keys 9 and 10 are open, and the keys 11, 12 are closed. Thus, the signal from the measurement unit 8 goes to the corresponding integrator 13 or 14 and through the key 10 or 12 to an appropriate reference source 4 or 5 magnetic field. The reference source 4 or 5 magnetic field creates a magnetic field gradient equal in magnitude and opposite to the measured intensity gradient field of the residual magnetization. From the output of the reference source 4 or 5 magnetic field signal equal to the intensity gradient field. residual magnetization, is fed to the inputs of the corresponding memory blocks 16 or 17, from the outputs of which the signals go to the calculation block 18 and then to the indicator 19,

Determining the gradient of the field strength directly on the surface of the product under test allows one to eliminate the interfering influence of the oscillations of the gap caused, for example, by paints and varnishes and other coatings, when determining the mechanical properties. The magnitude of the intensity gradient of the residual magnetization field on the product surface is determined as follows. The dependence of the magnitude of the gradient of the normal component of the magnetic field strength on the distance to the surface can be approximated with sufficient accuracy by

„And - Ng ° vHr TTkh

 - the gradient of the intensity of the residual magnetization field at a distance from the surface of the product;

vHrO is the gradient of intensity of the residual magnetization field on the surface of the product;

k - coefficient of proportionality.

The magnitudes of the gradients UNG1 and vHr2 of the intensity of the residual magnetization fields acting on

magnetically sensitive elements located at distances hi and h2 (hi Ah) are described respectively by the following expressions;

vHr1

1 + kh

from here we find ny

and uNg2-

1 + khi

and 1 + khi

7H, about

1 + to (TTT-g 5TG)

VHrO-UNG2 kh

7Hr1 pVHr2

equated to the right, we will find

UN - DNM UNG2 I Ah

vHri -VHr2

Determining the gradient of the normal component of the residual magnetization field on the surface of a controlled product according to r-radienthem intensity of the residual magnetization field at two distances from the surface of the controlled product significantly simplifies the manufacture of identical transducers, since the distance between the magnetically sensitive elements can be taken large enough (10-20 mm). An error in setting the distance between 0.1 mm magnetically sensitive elements will result in an error (1-0.5)% in determining.

Thus, the introduction into the device of four keys, two integrators, two reference sources of a magnetic field, a synchronization unit, two memory blocks, a computation unit, and their connection with known device blocks leads to a positive effect.

Claims (2)

1. A method for determining the mechanical properties of products made of ferromagnetic materials, which consists in that the product is magnetized by an axially symmetric magnetic field, a change in the gradient of the intensity of the residual magnetization field is measured, according to which the mechanical properties of the products, characterized in increasing accuracy, measuring the change in the intensity gradient of the residual magnetization field is carried out by a compensation method at two fixed distances from the surface of the product and calculate gradient of the field strength of the remanent magnetization on the surface of the article which is used in determining the mechanical properties of the products. 2. A device for determining the mechanical properties of products made of ferromagnetic materials, comprising a magnetization unit and an input solenoid connected to it with two magnetosensitive elements located at a given distance from its working end, a switching unit, a measuring unit and a series-connected calculation unit and an indicator, characterized in that, in order to improve accuracy, it is equipped with two chains, each which are made in the form of serially connected first key, the input of which is connected to the output of the measuring unit, integrator, second key, reference source mag0 and a memory unit and a synchronization unit, the first output of which is connected to the control inputs of the switching unit and keys, the second and third outputs are connected through one of the memory blocks to the corresponding inputs of the calculation unit, and the reference sources of magnetic pop are installed coaxially inside the solenoid Equal distance from the magnetically sensitive elements, the outputs of which are connected through the switching unit to the input of the measuring unit.