UA81658U - Method for magnetic-powder control of constructions made of ferromagnetic materials - Google Patents

Abstract

A method for magnetic-powder control of constructions made of ferromagnetic materials through magnetization of ferromagnetic surface with magnetic flux formed with permanent magnetic poles of magnetization device connected with a flexible magnetic conductor. The procedure of control is carried out in two steps – at the first step search of defects is performed, that for at least one pole fixed on split platform, equipped with bearing roller and supplementary elements installed in the slots of the lower surface of the platform without fixation and with possibility of free motion in all the directions between the walls of the slot is displaced by ferromagnetic surface in a little lifted on bearing roller state till instant of detection of a defect, after that the movable pole is stopped, at the second step – measurement of the defect detected is performed at tight contact of the lower surface of the split platform with the relief irregularities of the ferromagnetic surface.

Description

The useful model belongs to the non-destructive control of products by the magnetic method and can be used to determine the location of defective zones of structures and parts made of ferromagnetic materials. It will be most widely used in the detection of defects in welded joints, which are used in all industries.

The magnetic powder method of non-destructive testing is used to find surface and subsurface microdefects in welds, parts and structures made of ferromagnetic materials. For this purpose, the product is magnetized and covered with magnetic powder, which settles on the inhomogeneities of the magnetic field in the defect zone, forming visible "traces" of defects.

Magnetic powder control is widely used in aviation, chemical engineering, in the control of large structures, main pipelines, shipbuilding, automotive and many other industries, but it is especially widely and widely used in railway transport. This method has high productivity, visibility of control results and high sensitivity. With the correct technology of detail control, this method detects cracks and other defects in the initial stage of their appearance. For many parts, the magnetic powder control method is actually the only possible one.

The control of products with complex geometry, the surface of which has irregularities, protrusions, depressions, etc., requires special attention. Control of such products is extremely problematic.

It is obvious that the effectiveness of magnetic powder control is directly dependent on the nuances of the constructive construction of the equipment used.

In the known state of the art, numerous methods of conducting magnetic powder control using devices operating on permanent magnets are presented. Such devices and their operation are described, for example, in the book "Magnetic powder control of welded joints and machine parts" (V. A. Troitsky - K.: Feniks - 2002. - pp. 204-208).

A common disadvantage of magnetic powder control technologies, for which the devices mentioned in this book are used, is the complexity of the process and the insufficiently high degree of reliability of the information obtained. The reason for this is that almost all measurements are carried out in the so-called discrete mode, when the poles are selectively moved from place to place on the monitored surface and, accordingly, 3 of these places are recorded, while the places not covered by the poles can potentially be

They are dangerous from the point of view of the presence of undetected (missed) defects in them.

In addition, due to the insufficient magnetic conductivity of the junction zone of the surface of the controlled part and the pole, the discrete procedure is unable to provide effective control of surfaces that have some irregularities, bends, depressions, etc. In addition, the procedure itself requires considerable effort from the operator to overcome the force of attraction of the poles to the metal surface during repositioning and is quite dangerous, because when the poles are torn off, there is a high probability of injury if they hit the surface of the part.

The patent of Ukraine Mo 51871 (МПК":01М 27/84, publ. 10.08.2010, Bull. Mo 15, 2010) describes a method of magnetic powder control of a ferromagnetic surface with the use of a magnetizing device, which has pole rollers that include permanent magnets, rigidly connected to each other - they are coaxially screwed to the cylindrical yoke.In the process of control, the device is moved with the help of a handle along the defined zone.

The disadvantage of this method is that it is able to provide information about the presence of defects only in the zone concentrated between the rollers, and in order to adjust the magnitude of the magnetic flux and obtain complete information in all areas of the examined surface, it is necessary to periodically readjust the distance between them, which is extremely inconvenient and laborious operation.

According to a similar algorithm, magnetic powder control is carried out using a device that contains a coil and a magnetic wire consisting of a core and two poles, which include a package of plates (Russian Patent Mo 2016403, MPK8U:СО1М 27/84, publ. 07/15/1994). In the control process, to obtain more detailed information about the presence of defects in the product, it is also necessary to move and fix the pole plates with the help of special clamps.

From the patent of Ukraine Mo 679 (MPKU:С0О1М 27/84, publ. 16.10.2000, Byul. Mo 5, 2000) the technique of performing magnetic powder control of a ferromagnetic surface using a device that has a flexible magnetic wire with permanent magnetic blocks mounted on its ends is known ( poles). Compared to the previous one, this technique provides the possibility of control in a longer area thanks to the flexible connection between the poles. But at the same time, in order to adjust the inter-pole distance, it is necessary to detach and rearrange the poles, and this, in turn, will lead to the above-mentioned consequences that occur when the counter is carried out according to a discrete procedure.

The method of magnetic powder control of structures made of ferromagnetic materials by magnetizing the ferromagnetic surface with a magnetic flux created by the permanent magnetic poles of the magnetizing device, connected by a flexible magnetic conductor ("Magnetic powder control of welded joints and machine parts" V.A. - K. Troitskyi) is the closest analogue of the useful model. Phoenix - 2002. - P. 206, fig. 124a, pos. 4).

The procedure of magnetic powder control with this device consists in repeatedly alternating detachments and permutations of poles on the surface of the controlled part, that is, it is discrete, in which, as indicated above, the possibility of passing defects in areas not covered by the poles is not excluded. In addition, with each new exposure, to overcome the significant force of the magnetic field, which attracts the poles to the surface, significant efforts are required, which are often beyond the power of the operator.

The list of shortcomings of the known method is supplemented by the fact that it is not able to provide reliable information during the control of curved surfaces due to the impossibility of achieving full contact in the area of conjugation of the surface of the controlled part and the lower side of the pole.

The useful model is based on the task of increasing the informativeness and efficiency of the method of magnetic powder control of structures made of ferromagnetic materials by dividing it into two stages - searching and measuring, and by optimizing the conditions for each of them, in particular, by smoothly moving at the first stage at least one pole in a slightly raised on the support roller in the state until the defect is detected and by measuring the detected defect in the second stage when the poles are stopped and the surface unevenness is tightly covered by the disconnecting platform, as well as by shunting the magnetic flux in the first stage, which, in the absence of the need to separate the poles from the surface of the part and rearrangement, allows you to smooth movement of the pole and significantly expand the magnetic control zone, ensures reliable magnetic conductivity of the air gap zone during the movement of the pole on the surfaces of a complex geometric configuration and evaluation of the detected defect with a stationary magnetic field of maximum magn. electrical conductivity.

The problem is solved by the fact that in the method of magnetic powder control of structures made of ferromagnetic materials by magnetizing the ferromagnetic surface

With the magnetic flux created by the permanent magnetic poles of the magnetizing device, connected by a flexible magnetic conductor, according to a useful model, the control procedure is carried out in two stages - at the first stage, a search for defects is carried out, for which at least one pole is fixed on a removable platform equipped with a support roller and auxiliary elements installed in the grooves of the lower surface of the platform without fixing and with the possibility of free movement in all directions between the walls of the groove, are moved along the ferromagnetic surface in a slightly raised state on the support roller until the moment of detection of the defect, after which the movable pole is stopped, on the second - carry out measurement of the detected defect when the lower surface of the detachable platform closely fits the topography irregularities of the ferromagnetic surface. In addition, at the stage of searching for defects, part of the magnetic flux is shunted past the moving pole of the magnetizing device.

The presented method is implemented with the help of a device, the features of the constructive construction of which determine the advantages of this method over all magnetic powder control technologies, described according to the known state of the art, in particular, in the publication accepted as a prototype.

The movement of the pole along the ferromagnetic surface on the support roller creates the conditions to make the first stage of control (defect search period) smooth. At the same time, the magnetic field is not interrupted, as with the discrete movement of the pole, but is transformed and redistributed, leading to the movement of the magnetic powder and, as a result, to more effective detection of defects.

Auxiliary elements installed in the grooves of the lower surface of the detachable platform also provide additional smoothness to the movement of the poles. Thanks to these elements (they can be rollers, balls, rollers, inserts of various shapes), at the second stage of magnetic powder control (the stage of evaluating the detected defect), the possibility of tight fitting of the lower part of the removable platform of the movable pole to surfaces with significant irregularities and distortions is achieved. Thus, the second stage is carried out in conditions of almost complete absence of air gaps between the platform and the ferromagnetic surface. It is obvious that under such circumstances the efficiency of the control is much higher compared to that which is carried out according to the known method, where it was practically impossible to ensure a tight fit of the pole to the curved surface.

A significant advantage of the proposed technology is that in the process of searching for defects, part of the magnetic field can be shunted - when the shunt is lowered onto the part, a significant part of the flux past the flexible magnetic wire is closed, the total magnetic flux decreases, and the movable pole of the magnetizing device acquires the ability to move more smoothly than in the conditions strong field. Shunting is carried out by placing a magnetically conductive part (shunt) between the poles of the magnetizing device. As a rule, the fixed pole of this device is equipped with a shunt.

For greater informativeness in the context of the implementation of the proposed method using a magnetizing device, drawings are given (for example, a demonstrative device with a fixed and a moving pole), which shows: in fig. 1 - magnetizing device installed on the surface of the product, without shunting the magnetic flux; in fig. 2 - magnetizing device in the process of movement on the surface of the part (with the shunt lowered); in fig. C - magnetizing device during the evaluation period of the identified defect (with a raised shunt).

The method is carried out with the help of a device that contains two poles - stationary A, which is rearranged discretely, and mobile B, which moves freely on the surface of the part. The poles include several permanent magnets 1, 2. The poles are connected by a ferromagnetic magnetic circuit consisting of movable elements 3-8, connected with the possibility of rotation relative to each other in three spatial planes. The movable pole B is fixed on a removable movable platform 9, made in the form of an elliptical plate. A support roller 10 is placed in the end part of the platform. In the grooves 11 of the lower surface of the platform, auxiliary elements 12 are installed without fastening and with the possibility of free movement in all directions between the walls of the groove. The stationary pole A is equipped with a shunt 13 (fig. 2, 3). At the end of the moving platform 9, opposite from the support roller 10, a lifting handle 14 is fixed.

The device is installed on a pre-cleaned and prepared product for control (Fig. 1). The magnetic fields created by each magnet add up to create a total magnetic flux and magnetize the product. To detect defects, it is applied to the magnetized surface

The indicator is magnetic powder or magnetic suspension, which is concentrated on the edges of the defects - a powder pattern is formed in the area where the defect is located.

The process of detecting defects is carried out in two modes: search and evaluation. In the process of moving (searching for defects), the platform with the movable pole is moved on the support roller 10 with the help of the handle 14, slightly lifting it above the surface of the part (Fig. 2).

The search ("scanning") is carried out on a limited magnetic flux, for which the shunt 13 is lowered down (Fig. 2), while the entire magnetic flux is directed to the control zone.

At the moment of determining the location of the defect, the moving pole is stopped and the platform is lowered. Depending on the relief of the surface of the part, the separating plate together with the auxiliary rollers fits tightly to the latter, "enveloping" all the irregularities. The mode of evaluation of the indication - evaluation of the detected defect is coming. When the gap between the disconnecting platform and the surface of the part disappears, the tangential component of the magnetic flux increases. At the same time, the detection of defects increases as much as possible. Thus, the indication of defects occurs statically, in the mode of maximum magnetic flux, which is provided by raising the shunt 13 (Fig. 3).

Claims (2)

USEFUL MODEL FORMULA 1. A method of magnetic powder control of structures made of ferromagnetic materials by magnetizing a ferromagnetic surface with a magnetic flux created by permanent magnetic poles of a magnetizing device connected by a flexible magnetic conductor, which differs in that the control procedure is carried out in two stages - in the first stage, a search for defects is carried out, for which at least one a pole fixed on a detachable platform equipped with a support roller and auxiliary elements installed in the grooves of the lower surface of the platform without fixing and with the possibility of free movement in all directions between the walls of the groove, is moved along the ferromagnetic surface in a slightly raised state on the support roller until the moment of detection defect, after which the moving pole is stopped, on the second - the detected defect is measured when the irregularities of the topography of the ferromagnetic surface are closely abutted by the lower surface of the disconnecting platform. 2. The method according to claim 1, which differs in that at the stage of searching for defects, part of the magnetic flux 60 is shunted past the movable pole of the magnetizing device.