RU2486618C1 - Method of demagnetisation of ferromagnetic materials and device to this effect - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: known method involves a demagnetising variable magnetic field created at least by two electromagnets consisting of flat-topped magnet cores with coils wound on them. Electromagnets are located over the article so that the distance between poles of one electromagnet is equal to the distance between poles of adjoining electromagnets. In the device used to implement this method adjoining electromagnets are connected to frequency converter in synphase. All electromagnets can be moved along a flexible construction. Poles of one electromagnet are located at the distance equal to the distance between poles of adjoining electromagnets.

EFFECT: provision of demagnetising with value up to 1 mT per one pass, which results in reduction of costs for repeated passes.

6 cl, 14 dwg

Description

The group of inventions relates to the field of demagnetization of ferromagnetic materials and products and can be used to remove the residual magnetic induction of pipes, long and flat products in the production lines of metallurgical plants.

High residual magnetic induction leads to a number of adverse consequences during further processing and operation of products from ferromagnetic materials:

- poor-quality welding during docking due to "magnetic blast";

- failure of the cutting tool during machining due to sticking chips.

If, for example, the pipe is not demagnetized to the level specified in the standard for the production of this pipe, then it cannot be recognized as suitable products and must be rejected by the manufacturer.

The task to which this group of inventions is directed is the creation of technology and equipment for the demagnetization of products from ferromagnetic materials, which guarantee the demagnetization of products to values of the order of 1 mTl in one pass, which reduces the cost of the manufacturer for repeated runs.

There is a method of demagnetization of a ferromagnetic product, which consists in heating the product to the Curie point, at which the magnetization disappears (Non-Destructive Testing and Diagnostics. Handbook edited by V.V. Klyuev, M., Mechanical Engineering, 1995, p.243-244). The disadvantage of this method is a change in the mechanical properties of the material of the product as a result of heating, and in most cases this is unacceptable.

A known method of demagnetization of long products from soft magnetic materials, mainly pipelines, in which the long product is exposed to a magnetic field, which is carried out by at least one magnetizing belt with magnetizing poles, and the change in the magnetic field is achieved by moving the magnetizing belt along the long product, while magnetizing lead from the inside of a long product with a magnetizing belt containing at least two opposite poles nennyh wedge-shaped and formed by permanent magnets (RF patent №2335819, cl. H01F 13/00, 2006).

The disadvantage of this method is that it can be used only in pipelines in the field and is not suitable for use in workshop conditions, in addition, to demagnetize sheet, long products and other products, it is necessary to have additional equipment.

There is a method of demagnetization of products made of ferromagnetic materials, including exposure to a product of a magnetic field with an amplitude decreasing from a certain value to zero, and a frequency depending on the magnetic permeability and thickness of the product, demagnetization is carried out locally by a demagnetizing variable magnetic field (RF patent No. 2258272, class. H01F 13/00, 2003).

The above method has several disadvantages. Firstly, it is applicable only for products of small-diameter rolling products of small diameter and is not applicable for the demagnetization of large diameter pipes and sheets. If the product is a pipe with a diameter of 1420 mm, a large magnetic path along the circumference of the pipe will lead to inefficiency of the device, because a critical decrease in the level of magnetic flux in the demagnetized product will occur. The conservation of energy exposure to magnetic dipoles in the product material will require much greater energy costs. Secondly, mechanical movement of the coil along the core is required to demagnetize the last section of the product. When demagnetizing a large number of products, high demands are made on the mechanical strength and wear resistance of the mechanism performing such a movement. This entails the high cost of the mechanism.

This technical solution is taken as a prototype according to the claimed invention to the method.

The essence of the invention lies in the fact that the inventive method of demagnetization of products from ferromagnetic materials allows you to efficiently demagnetize various ferromagnetic products of rolling and pipe production with the same set of equipment with minimal material costs.

This is achieved by the fact that in the method of demagnetization of products made of ferromagnetic materials, including exposure to a product of a magnetic field with an amplitude decreasing from a certain value to zero, and a frequency depending on the magnetic permeability and thickness of the product, demagnetization is carried out by a locally demagnetizing alternating magnetic field, the demagnetizing variable the magnetic field is created by at least two electromagnets consisting of U-shaped magnetic circuits with coils wound on them, while the electromagnets p positioned over the product so that the distance between the poles of one electromagnet is equal to the distance between the poles of adjacent electromagnets, and the distance from the electromagnet magnetic circuit to the surface of the product is less than half the distance between the poles of the electromagnets, an in-phase alternating voltage of adjustable frequency is applied to each electromagnet, the product is demagnetized during its movement . When demagnetizing sheet metal, electromagnets are placed in one line across the width of the product. When demagnetizing products of complex closed cross-sectional shape, electromagnets are placed around the perimeter of this section. The number of electromagnets is selected depending on the length or perimeter of the product.

The inventive method of demagnetization of products from ferromagnetic materials allows you to demagnetize a large assortment of products in the workshop with the same set of equipment.

The inventive method of demagnetization of products from ferromagnetic materials can be carried out using the proposed device.

The inventive method of demagnetization of products from ferromagnetic materials and a device for its implementation are united by a single inventive concept, since the device allows to implement a method of demagnetization of products from ferromagnetic materials with the above technical result.

A device for the demagnetization of long ferromagnetic products, containing a demagnetization unit, made in the form of an oscillating circuit, consisting of a solenoidal coil with a ferromagnetic core connected to a capacitor bank, a metal sensor associated with the controller (RF patent No. 22528272, MCP H01F 13/00, 2003).

A device for removing residual magnetic induction of ferromagnetic products, containing a demagnetizing device, sensors for the presence of the product and sensors of residual magnetization (RF patent 2339108, MCP H01F 13/00, 2007).

Both known devices have several disadvantages. They are difficult to use in practice in production conditions, for example, in pipe production. Known devices have in their composition, mainly non-standard components. This makes it difficult to manufacture such devices, increases their cost and reduces their maintainability in the production environment of the workshop. In addition, both of these devices do not provide the removal of residual magnetic induction to the required values.

The closest in technical essence and the result achieved when using the claimed device is an automated complex for removing residual magnetic induction of ferromagnetic products, containing a demagnetizing unit connected to a frequency converter, electrically connected to the control unit, product availability sensors, sensors of residual magnetization (application for a utility model No. 20111137173, 2011, which decided to grant a patent).

This technical solution is taken as a prototype of the claimed device.

The known invention is intended to demagnetize only pipes and long products, in addition, one set of equipment is intended only for one diameter.

The essence of the invention lies in the fact that the claimed design ensures the implementation of the method by performing in a certain way electromagnets and their location.

This is achieved by the fact that in the device for implementing the method comprising a demagnetizing unit connected to a frequency converter, electrically connected to a control unit, product presence sensors, remanent magnetization sensors, a demagnetizing unit is made in the form of at least two electromagnets consisting of U-shaped magnetic circuits with coils wound on them, adjacent electromagnets are connected to the frequency converter in common mode, while all electromagnets are mounted with the possibility of moving n and in a flexible design, the poles of one electromagnet are located at a distance equal to the distance between the poles of the adjacent magnets, and the distance from the magnetic circuit of the electromagnets to the surface of the product is less than half the distance between the poles of the electromagnets. At the same time, the flexible design is made, for example, in the form of a truck.

The advantages of the claimed device include versatility during demagnetization of products of various shapes and lengths.

The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information containing information about analogues of the invention for both the method and the device, made it possible to establish that analogues that are characterized by the features of the claimed method and device were not found, but from the list of identified analogues selected prototypes for both the method and the device, which allowed to determine the distinguishing features of the proposed method of demagnetization of products from ferromagnetic materials and devices for its implementation. According to the applicant, the claimed group of inventions meets the criterion of "novelty" under the current law.

Technical solutions claimed in the group of inventions do not follow explicitly from the prior art, therefore, it meets the criterion of "inventive step".

To confirm the industrial applicability of the group of inventions, the drawings are given. In Fig.1 is a block diagram of a device for implementing the method, in Fig.2 is an electromagnet, in Fig.3 is the direction of the magnetic flux obtained in the first half-wave of an alternating voltage applied to the electromagnets, using the demagnetization of a sheet product as an example, in Fig.4 - the direction of the magnetic flux obtained in the second half-wave of alternating voltage applied to the electromagnets, using the demagnetization of a sheet product as an example, in FIGS. 5, 6, 7, 8 - similarly to FIG. 3 and FIG. 4, but for pipes, in FIG. 9 and figure 10 - similarly to figure 3 and figure 4, but for a round bar see figure 11 - the location of the electromagnets when demagnetizing a thick sheet of small width, figure 12 - the location of the electromagnets when demagnetizing a wide thin sheet, figure 13 - the location of the electromagnets to demagnetize the pipe, figure 14 - the location of the electromagnets for demagnetizing the bar .

A device for demagnetizing products from ferromagnetic materials contains a demagnetizing unit 1 connected to a frequency converter 2, electrically connected to a control unit 3, sensors 4 and 4 'of the presence of the product 5 and sensors of residual magnetization (not shown). The demagnetizing unit 1 is made in the form of at least two electromagnets 6, consisting of U-shaped magnetic circuits 7 with coils 8 wound on them. Electromagnets 6 are connected to the frequency converter 2 in common mode. The electromagnets 6 are mounted to move on the guides 9 of the flexible structure 10, made, for example, in the form of a truck. The poles of one electromagnet 5 are located at a distance L equal to the distance between the poles of the adjacent electromagnets 6. The distance H from the magnetic circuit of the electromagnets 6 to the surface of the product 5 is less than half the distance L between the poles of the electromagnets 5.

The principle of the method of demagnetization of products from ferromagnetic materials is shown by the example of the operation of the device for implementing this method.

A device for implementing the method of demagnetization of products from ferromagnetic materials works as follows.

The product 5 enters the demagnetization zone, the product presence sensor 4 sends a signal to the control unit 3, which through the frequency converter 2 supplies an alternating voltage to each electromagnet 6. Each local part of the product 5 during the movement is at the point of maximum influence of the demagnetizing field of the electromagnets 6, and then it moves away from this point, resulting in the attenuation of the demagnetizing field to "zero", and as a consequence of this, the product 5 is demagnetized. When the demagnetization of sheet metal (11, 12), the electromagnets 6 are located on one line across the width of the product 5. The location of the poles of the adjacent electromagnets 6 at a distance L eliminates the closure of the power lines from the N pole to the S pole bypassing the product material 5. To the adjacent electromagnets 6 serves voltage in common mode, thereby obtaining a magnetic flux not only between the poles of one electromagnet 6, but also a magnetic flux between adjacent electromagnets. In this case, all the material of the product 5 is exposed to a demagnetizing alternating magnetic field. Thus, a demagnetizing variable magnetic flux is obtained in each section of the product 5, and when moving the product under the electromagnets 6, the entire product is demagnetized along its entire length. During the movement of the product 5, the sensor 4 'detects the end of the product and sends a signal to the control unit 3, which turns off the demagnetization device.

When demagnetizing a narrow sheet product (11), the electromagnets 6 that are not involved in the demagnetization are lifted along the guides 9 of the flexible structure 10. The demagnetization process is described above.

When demagnetizing products of circular cross-section (Fig.13, 14), the flexible structure 10 goes around the product 5 around the perimeter, and the electromagnets 6 along the guides 9 are set to the appropriate size.

A prototype of a device implementing the claimed method was manufactured and tested. The test results showed that the level of residual magnetic induction after demagnetization was less than 1.5 MT.

Thus, the claimed group of inventions is industrially applicable and gives the positive effect described above.

Claims (6)

1. The method of demagnetization of products made of ferromagnetic materials, including exposure to a product of a magnetic field with an amplitude decreasing from a certain value to zero, and a frequency depending on the magnetic permeability and thickness of the product, demagnetization is carried out locally by a demagnetizing variable magnetic field, characterized in that the demagnetizing variable a magnetic field is created by at least two electromagnets consisting of U-shaped magnetic circuits with coils wound on them, while the electromagnets are located lays over the product so that the distance between the poles of one electromagnet is equal to the distance between the poles of adjacent electromagnets, and the distance from the electromagnet magnetic circuit to the surface of the product is less than half the distance between the poles of the electromagnets, an in-phase alternating voltage of adjustable frequency is applied to each electromagnet, the product is demagnetized during its movement . 2. The method according to claim 1, characterized in that when the demagnetization of sheet metal, the electromagnets are placed in one line across the width of the product. 3. The method according to claim 1, characterized in that when the demagnetization of products of complex closed cross-sectional shape, the electromagnets are located around the perimeter of this section. 4. The method according to claim 1, characterized in that the number of electromagnets is selected depending on the length or perimeter of the product. 5. The device for implementing the method according to claim 1, comprising a demagnetizing unit connected to a frequency converter, electrically connected to the control unit, product presence sensors, residual magnetization sensors, characterized in that the demagnetizing unit is made in the form of at least two electromagnets, consisting of U-shaped magnetic circuits with coils wound on them, adjacent electromagnets are connected to the frequency converter in common mode, while all electromagnets are mounted with the possibility of movement I am on a flexible design, the poles of one electromagnet are located at a distance equal to the distance between the poles of the adjacent magnets, and the distance from the magnetic circuit of the electromagnets to the surface of the product is less than half the distance between the poles of the electromagnets. 6. The device according to claim 5, characterized in that the flexible structure is made, for example, in the form of a truck.

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