RU1797032C - Method of magnetic-tape testing of articles made of ferromagnetic materials - Google Patents

Abstract

The invention relates to magnetographic flaw detection, and is mainly intended for the detection of continuity defects in large-sized products when, based on statistical data, it is known that the number of defects is small (parts of helicopters, airplanes, turbines). The purpose of the invention is to increase productivity in the control of large items. For this, in the method of magnetographic control, which consists in magnetizing the controlled product together with the magnetic tape in contact with its surface and then reading the magnetogram thereon, magnetization is carried out along the magnetic tape, the tape is stretched perpendicular to the magnetized direction and reading is carried out along magnetic tape and, as a result of reading, are applied to the surface of the product defect lines. Then the whole process is repeated in the perpendicular direction, after which the intersection points of the defect location lines are further monitored. 4 ill. (L C

Description

. The invention relates to magnetographic flaw detection and can be used to control the quality of products made of ferromagnetic materials, mainly for detecting continuity defects in large-sized products, when it is known on the basis of statistical data that the number of defects is small (parts of helicopters, airplanes, turbines).

A known method of magnetographic inspection of products from ferromagnetic materials for the presence of surface and subsurface defects, which consists in the magnetization of the controlled product, the magnetized surface relief of the product is transferred onto

a ferromagnetic carrier pressed firmly to the surface of the article reads information about the magnetic relief from the carrier, which is used to determine the presence of defects.

Its disadvantage is low labor productivity in the control of large products.

There is also known a method of magnetographic inspection of products made of ferromagnetic materials, which consists in the magnetization of the controlled product in conjunction with its contacting surface and the magnet carrier supported by sliding at a distance of | then 21 in the opposite direction, and the defect position is determined by V |

YU

3

with

Yu

They are given as the midpoint of the resulting magnetic relief on the tape.

The closest in technical essence and the achieved result to the invention is a method of magnetographic inspection of products made of ferromagnetic materials / which consists in magnetizing the controlled product, transferring the magnetized relief from the surface of the product to a ferromagnetic carrier in contact with the surface of the product and stretched with sliding relative to the surface of the product, information on the magnetic relief is read from the carrier, which is used to determine the presence of defects s.

A disadvantage of the known method is the low labor productivity when monitoring products of large sizes. This drawback is due to the fact that the known method of magnetographic control does not allow the product to be monitored by sections whose width exceeds the width of the magnetic tape.

The known method of magnetographic control involves placing a magnetic carrier in the interpolar space along the poles of a magnetizing device with subsequent recording of the magnetic relief. The control zone in this case is small and does not exceed the width of the magnetic tape. In order to control the entire surface of a large-sized product, it is necessary to repeatedly control sections with a width of not more than 35 mm. Therefore, the known method of magnetographic control of large-sized products is inefficient.

The purpose of the invention is to increase productivity in the control of large items.

For this, in the method of magnetographic inspection of products made of ferromagnetic materials, which consists in magnetizing the controlled product together with a magnetic tape in contact with its surface and stretched relative to it, a magnetogram is read and the read result is used to determine the presence of defects. According to the invention, magnetization is carried out along the magnetic tape, the tape is stretched perpendicular to the direction of magnetization, reading is carried out along the magnetic tape and, as a result of reading, the defect lines are applied to the surface of the article, then the entire process is repeated in the perpendicular direction, and then additionally control cross-sectional points of defect lines.

The control zone, covered in one pass of the electromagnet in this case, is much larger than with the known method, which saves time. Figure 1 shows the controlled product together with the magnetic tape laid in its original position: in FIG. 2 - magnetic tape with marked on her

surface magnetic prints due to defects; Fig. 3 shows a product with lines marked on it for the possible location of defects when moving the tape in one direction;

5 in Fig. 4 is the same, but when moving the tape in two mutually perpendicular directions.

The method is carried out as follows.

0 Previously, the magnetic tape 1 is tied to the product 2, for example, by indicating the position of the edge of the LED product on the tape (Fig. 1). When pulling magnetic tape 1 with sliding across the tape

5 and upon magnetization of the article 2 containing defects 3 and 4, along with the tape along the tape (in the direction of arrow H), strips of magnetic fingerprints 5,6 are formed on the tape, corresponding to defects and oriented along the cross of the tape (Fig. 1,2). If the recording from the tape is read in the transverse direction, then the position of the prints 5 and b (Fig. 2) will not be determined, since the gradient of the magnetic field across the tape is zero. Reading

5 recording from a tape in the longitudinal direction, it is possible to determine the position of the strip-indicated magnetic prints 5 and 6 on the tape (figure 2). Re-tied the magnetic tape to the product along the lines of LEDs and

At the edge of the article, there are lines 7 and 8 of the possible location of defects in the article (Fig. 3). Then, similarly, the product is controlled in the direction perpendicular to the original, and the position of lines 9 and 10 of the possible location of defects and the intersection of these lines E, F, G, H with the previously marked lines 7 and 8 are determined (Fig. 4) points E, F, G, H are exposed, according to the results of which defects 3 and 4 (Fig. 1) are determined at points E and G (Fig. 4). In another embodiment, after determining the lines of a possible defect location. 7 and 8 (Fig. 3) magnetic tape is applied to these lines and the control is carried out

5 in the traditional way, while detecting defects Zi4 (Fig. 1) at points E and C. If the magnetic tape is not moved across, then the surface monitored in one pass of the magnetizing device will be smaller.

If the recording from the tape is not read in the longitudinal direction, then the amplitude of the signal from the defect will be less, since the reading is not carried out along the magnetization line.

Example 1, a rolled sheet with dimensions of 1400x1400x6 mm was controlled by the method of magnetographic control adopted for the prototype. Used magnetic tape type I4701-35 (width 35 mm). The control was carried out alternately by sections. Magnetization was carried out with typical

PNU-1 moving magnetizing device. The time for control was 2 hours 10 minutes.

Example 2. The same sample was controlled by the proposed method. The tape was in the pole space of an electromagnet 240 mm wide. The time for control was 21 minutes.

The application of the proposed method of magnetographic control will improve the performance of control products of large sizes. .

FORMULA AND SECTION

The method of magnetographic inspection of products made of ferromagnetic materials, which consists in magnetizing a controlled product, together with a magnetic tape in contact with its surface and being drawn relative to it, reading a magnetogram and using the reading result to determine the presence of defects, characterized in that, in order to increase make $ ig. f

During the inspection of large products, magnetization is carried out. along the magnetic tape, the tape is perpendicular to the direction of magnetization, the reading is carried out along the magnetic tape and, as a result of reading, the defect lines are applied to the surface of the article, then the whole process is repeated perpendicular in the opposite direction, after which the intersection points of the defect location lines are further controlled.

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