SU1651251A1 - Device for control of ferromagnetic articles - Google Patents

Abstract

The invention relates to magnetic measurements and can be used for non-destructive quality control of products made from ferromagnetic materials. The purpose of the invention is to improve the control accuracy by reducing the influence of the gap. A device for monitoring ferromagnetic products contains an open magnetic circuit, closed by a controlled product, with magnetizing coils measured on the magnetic core, as well as a magnetic parameter meter. The ferromagnetic body, the piping (the iR zone of the fluxes of the scattering of the magnetic field near the latter from the product side, as well as two identical non-ferromagnetic gaskets placed on the magnetic pole, compensate for the losses of the working magnetic flux of the magnet when the gap increases, so the meter does not hang t from the size of the gap in a wide range of its change (1.5-6 mm). 3 ill. i (I С

Description

The invention relates to magnetic measurements and can be used for non-destructive quality control of products made from ferromagnetic materials.

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

FIG. 1 shows a device for controlling ferromagnetic products, front view; in fig. . - the same, top view; in fig. 3 - dependences of the residual magnetic flux of the magnetic conductor on the size of the gap between the poles of the magnetic core and the product without a ferromagnetic body (2) and with the installation of a ferromagnetic body (1).

The device contains an open U-shaped magnetic circuit 1, which is closed by the test item 2, with magnetizing winding 3 placed on the magnetic core 1, and also measured. The magnetic parameter body 4 and the ferromagnetic body (jumper) 5. Between the poles of the magnetic circuit 1 and the product under test 2 are placed two identical non-ferromagnetic spacers 6.

The device works as follows.

The product 2 is mounted on the gaskets 6. After magnetic preparation, consisting in the reversal of the product 2, and with it the body 5 by

the passage through the magnetizing winding 3 of different-polarity electric current pulses, which ensures the detuning from the influence of the magnetic history of the product 2 and the ferromagnetic body 5, the product 2 is magnetized to technical saturation. The resulting scattering flow, proportional to the magnitude of the non-ferromagnetic gap, the magnitude of which is made up of the thickness of the gaskets 6 and the random gap between the surface of the product 2 and the gaskets 6, magnetizes the ferromagnetic body 5. After removing the magnetizing field, the ferromagnetic body 5 has a magnetically-motive force that compensates the change due to the random gap of the magnetic flux in the magnetowire- 1} generated by the magnetomotive force of the product 2, measured by the meter 4. For the selected sizes The thickness of the material, the location and location of the ferromagnetic body 5 in the non-ferromagnetic gaskets 6 is determined experimentally from the condition that the control result is independent of the thickness of the gaskets 6. The presence of such an effect can be clarified as follows.

A disadvantage of the known device is to reduce the contribution of the magnetic flux from the product 2 to the total magnetic flux of the magnetic circuit 1 with an increase in the gap, which causes a measurement error. This disadvantage is due to the fact that, with an increase in the gap, the scattering flows increase accordingly; when magnetizing the product 2 is magnetised, and when remagnetizing a part of the useful flux is dissipated. At the same time, the flux of the dissipated during magnetization is determined by the magnitude of the non-ferromagnetic gap, and the flux of the dissipation decreases from the poles of the magnetic circuit 1. with . When introducing a ferromagnetic body 5 placed at such a distance from the magnetic core in the scattering flow zone, with this gap, the scattering flow arising from magnetizing products 2 will remagnetize the body 5 along a partial hysteresis loop, whose apex lies in the linear portion of the curve magnetizing the material of the ferromagnetic body, changing the gap between the product and

d r p 5

5 0 0 5

0

five

the magnetic conductor leads to magnetic reversal of the body 5 along the other partial hysteresis loop of the congruent first, and the magnetically moving force of the body 5, determined by the coercive force of the latter on the specified partial hysteresis loop, is proportional to the gap size. In addition, the magnitude of the coercive force of the body 5 is determined by the coercive force of the material of the Body 5 according to the limiting hysteresis loop and permeability on the back of this loop. When a ferromagnetic body 5 is selected, the magnitude of its magnetomotive force is determined by the length of the average line of force in the body 5, i.e. its size. With the selected material, size and location of the body 5 and at a fixed gap between the magnetic core 1 and product 2, the magnetically moving force of the body 5 is determined by the magnetically moving force of the winding 3 and the distance from the magnetic core 1 to the body 5. The magnetic motive force of the body 5 obtained after removing magnetizing field (after the magnetic preparation), creates a magnetic flux in the magnetic circuit 1, the magnitude of which (for a given location of the body 5) is proportional to the size of the gap. A similar flow from product 2 has an inverse relationship to the gap. At a certain gap between the product 2 and the magnetic core 1, the increment of this gap in some limits will cause the same magnitude, but different in sign, increment of magnetic fluxes created in the magnetic core 1 by the product 2 and the body 5, so that the total flux in the magnetic core 1 changes There will not be. The size of this gap will determine the thickness of the gaskets 6.

Under these conditions, the magnetomotive force of the body 5 compensates for the loss of the magnetomotive force of product 2 due to the influence of the gap, which allows the device to be used to control ferromagnetic products by measuring the magnetic characteristics measured on the back of the hysteresis loop (residual induction, coercive force, relaxation coercive force, etc.).

For example, the magnetic core 1 was made of Armco iron 50 mm high with an interpolar distance of 30 mm and a cross section of 10x20 mm2. In the neutral plane of the magnetic circuit 1 is made

five

1 mm incision tol1: 01noy, in which Hall dashnks of the type PKE60501 7A were placed. The magnetizing winding of 2x300 turns of the NETS-2 wire with a diameter of 0.83 mm and a height of 30 mm was placed on the rods of the magnetic core 1.

The amplitude of the magnetized pulses is 20 A. A sample of X12O1 steel after quenching with a coercive force of 40.2 A / cm was used as a ferromagnetic body 5. The dimensions of the sample are PhxPx50 mm3, it is located at a distance of 3.4 mm from the poles. To determine the thickness of the non-ferromagnetic gaskets 6, the residual flux in the magnetic conductor was removed (after magnetization and re-magnetization by two different-polarity pulses) on the size of the gap between the poles of the magnetic circuit 1 and the product 2. The gap was modeled using non-ferromagnetic plates. As a product 2, a sample of ZOIM2 steel with dimensions 9x9x50 mm3 with a coercivity of 5 A / cm was used. As can be seen from FIG. 3 (curve 1), starting with 1651251

The bore is 1.5 mm, the magnitude of the residual magnetic flux measured by the R magnet conductor does not depend on further variations of the gap, so you can choose b 1.5.

Thus, the proposed device allows to significantly increase the reliability (accuracy) of the control, as well as to control the products without having to put stringent requirements on the surface of the latter.

Claims (1)

Invention Formula A device for monitoring ferromagnetic products, comprising a U-shaped magnetic circuit with a magnetizing winding and a magnetic parameter meter, characterized in that that, in order to increase the control accuracy, it is equipped with a ferromagnetic core and two non-magnetic spacers, and the ferromagnetic jumper is placed at the poles of the magnetic core, on which non-magnetic spacers are located. 15 1 four FIG. 2 in, mm