SU947738A1 - Method of non-destructive checking of ferromagnetic material articles - Google Patents

Description

The invention relates to instrumentation engineering and can be used for non-destructive control of the mechanical characteristics of products made of ferromagnetic materials.

There is a method of non-destructive testing of magnetic materials, which means that the controlled magnetic materials are placed in a magnetic field and exposed to mechanical stresses within the elastic deformation region.

In this method, an alternating magnetic field is used, mechanical stresses are created by compressing or stretching, and mechanical properties are determined from a difference signal of the magnitude of the induction measured by an AO and after application of load 1.

However, this method has a significant drawback - magnetization occurs to a small depth due to the influence of eddy currents.

The closest in technical terms to the present invention is a method of non-destructive testing of products made of ferromagnetic materials, which means that the product is re-magnetized by a constant magnetic field and influenced by ultrasound, and the mechanical properties are determined by the magnitude of the variable induction component in it 2 with the disadvantage of this method

The reliability of the control is low due to the influence of the shape, size of the product under test and its initial magnetic state at 0 a fixed value of the magnetic field strength.

The purpose of the invention is to increase the reliability of the control.

The goal is achieved by the fact that in the method of the indestructible

15 control of products made of ferromagnetic materials, concluded that the product is re-magnetized by a constant magnetic field and affected by the level of 1; .without him.

25

The drawing shows a diagram of the device, realizing the method of control.

The device contains a magnetization unit 1 (BN), key 2, source 3

Claims (2)

30 Wuku ultras, meter 4 time intervals, Barkgaue noise amplifier 5 on, magnetizing coil L, and from the measuring coil Ik. The method is carried out as follows. In the initial state, at the output of the BN 1 there is a voltage Uy) x which is applied to the magnetizing coil L. A constant voltage Uj is applied to the input of the BN 1, and simultaneously the meter 4 is switched on. The voltage at the output of BI 1 begins to change as it approaches k. The magnetization reversal of the product 6 is induced. Barkhausen jumps induced in the coil L are fed through the amplifier to the input BN 1 and control the speed of the magnetization reversal (the more jumps, the lower the rate of change of the output voltage BN 1 providing a constant number of jumps in time. If The output of BN 1 changes quickly enough, the product quickly remagnetizes, the number of jumps increases, and the average voltage from the amplifier 5 to the input of BN 1 also increases. This voltage in the BN 1 unit Because of the voltage applied, the rate of change of the output voltage, BL 1, and the number of Barkhausen jumps are reduced due to a decrease in the magnetization reversal rate of the product. Thus, the reversal mode is performed with the Barkgausen jumps constant. B№ 1 will reach key 2 turns off the meter 4 time intervals.The time recorded by the maker 4 carries information about the number of Barkhausen jumps that occurred during the remagnetization, and the number of jumps depends m article sizes, magnetic properties and other factors). After that, the voltage is removed from the BN 1 input and the readings of meter 4 are reset and the device returns to its original state. Then, sources 3 of ultrasonic vibrations are turned on, and the voltage Ua ' The measurement cycle is repeated to the input BN 1. However, i in this case, the product is subjected to mechanical stresses caused by ultrasonic vibrations, and the number of Barkhausen jumps increases, consequently, the time of magnetization reversal also increases. This time in this case carries information not only of the 6 sample sizes, magnetic properties, but also about its mechanical characteristics. And the difference between the first and second readings is determined only by the mechanical properties of the sample. The Barkhausen jump parameters are sensitive to mechanical stresses, and since the sample magnetization time is determined by the number of jumps, the difference between the sample magnetization time in the presence of mechanical stresses caused by ultrasonic vibrations and without them depends only on the mechanical characteristics, and the effect other factors will be insignificant. Due to this, the reliability of the control is increased. Claims The method of non-destructive testing of products made of ferromagnetic materials, is that the product is re-magnetized by a constant field and magnetised by ultrasound, characterized in that, in order to improve the reliability of control, the magnetic reversal is carried out in the Barkhausen mode of constant jumps. and the monitored parameters are determined from the difference in the magnetization reversal times with and without ultrasound. Sources of information taken into account in the examination; 1. USSR author's certificate number 370517 / class. G 01 N 27/86, 1971. 2. Authors certificate of the USSR 549732, cl. G 01 N 27/86, 1973 (prototype) ...