WO2005091314A1

WO2005091314A1 - Polymeric magnetic strip with a relief and device for magnetisation

Info

Publication number: WO2005091314A1
Application number: PCT/EP2005/001022
Authority: WO
Inventors: Thomas Lanzl
Original assignee: Rehau Ag + Co
Priority date: 2004-02-19
Filing date: 2005-02-02
Publication date: 2005-09-29
Also published as: DE102004008068A1

Abstract

The invention relates to a polymeric magnetic strip (1), comprising ferromagnetic particles and polymeric material, with transverse reliefs and arrangement of all magnetic poles on one side, whereby the cross-section of the magnetic strip has at least one relief (2) between the separate adjacent pole surfaces (3) in an axial arrangement, and the wall thickness of the magnetic strip (1) is essentially uniform. The aspect ratio of a rectangle, enclosing the magnetic strip cross-section, is ca. 9: 2 in length and width and the separation of the pole surfaces (3) is a maximum of 10 mm, whereby the series of pole surfaces (3) have alternating different magnetic polarities.

Description

Polymeric magnetic tape with recess and device for magnetization

The invention relates to magnetic tapes made of polymer material with cutouts in the tape cross section and a device for magnetizing such tapes.

According to the prior art, polymeric magnetic tapes consist of mixtures in which ferromagnetic particles are bound by a polymeric material.

A magnetic thermoplastic extrudate is described, for example, in US Pat. No. 5,990,218 and the composition is given.

Magnetic tapes made of polymer material are used in refrigeration cabinets, in particular in refrigerators and freezers and in other areas of use. These magnetic tapes are generally arranged in hollow chambers of sealing profiles and take over the function of the door lock due to the magnetic adhesive force between the tape and the iron sheet of the refrigerator. In addition, make sure that there are no gaps between the sealing profile and the cabinet body.

The known magnetic tapes essentially have a rectangular cross section. This is shown by way of example in DE 20023 001 U1.

The magnetization of such a magnetic tape made of polymer material is given, for example, in JP 000062247513.

By applying a magnetic field to a magnetic tape, a magnetic pole is formed on opposite sides of the cross section. This has the disadvantage that only the adhesive force of one pole is available for guard locking. In an improved version, commercially available magnetic tapes with a rectangular cross section are magnetized such that all magnetic poles are arranged on one side of the cross section. For this purpose, the elementary magnets present in the ferromagnetic particles are aligned almost semicircularly to one side, in a preferred embodiment two such semicircular field line courses are arranged side by side, so that three polarizations in alternating order (e.g. NSN or SNS) on one on the adhesive surface of the magnetic tape Side of the cross section are formed extending in the axial direction.

These magnetic tapes produced according to the known prior art have the disadvantage that certain areas in the tapes (e.g. in the corners) do not or only ineffectively contribute to the magnetic adhesive force.

Furthermore, these tapes are relatively stiff and not very flexible, which makes them prone to breakage and leads to problems in production and processing.

The magnetization of these tapes takes place immediately after the shaping in the extrusion process, this being carried out by means of a pulse magnetization process, in which a current surge generates a magnetic field in a conductor, which is amplified by a suitable device made of soft iron and introduced into the magnetic tape.

After the magnetization process, the magnetic tape adheres to this device, which considerably increases the sliding resistance of the tape. This has considerable disadvantages in the production of the magnetic tapes. This can lead to the tape tearing off under unfavorable conditions. This limits the production speed.

The object of the invention is to optimize the relationship between the cross-sectional area of the magnetic tape and the generated adhesive force and to specify a magnetic tape which is more flexible and which has advantages in handling, in winding and in further processing.

Another object of the invention is to provide a device for magnetizing the magnetic tape which does not have the disadvantages mentioned, in particular the adherence to iron parts of the magnetizing device. The object is achieved by a magnetic tape with the features of claim 1.

Embodiments of the invention are described in the subclaims.

Furthermore, the object is achieved by a device for magnetizing the band according to the invention with the features of claim 6.

The magnetic tape according to the invention is obtained by the shape of the cross section of the magnetic tape by largely eliminating the areas which are magnetically ineffective or contribute little to the adhesive force, the material requirement for such a magnetic tape being considerably reduced. The cross-section of the magnetic tape is adapted to the field line course of the magnetization process, thereby optimizing the relationship between the cross-sectional area and the generated adhesive force.

Starting from the known circular field line course around a point-shaped conductor, it was recognized that the simplest solution for a magnetic tape optimized in cross section is an approximately semicircular arc that has a uniform wall thickness. An approximately semicircular recess is arranged between the pole faces of the magnetic tape.

High-performance holding magnets are adapted in their geometry to the respective material and the installation situation in order to optimize the holding force. Relevant in this context are the demagnetization curve of the material, the average length of the magnet along the field line in the magnet body, and the dimension of the space between the magnetic surface and the iron sheet. The adhesive force is optimized by adapting the mean length of the magnet to the other parameters mentioned.

In the magnetic tape according to the invention, the mean field line length, and thus the mean length of the magnet, is determined by the radii of the inner and outer contours of the arc and can be adapted to the respective space between the magnetic tape and the refrigerator plate in the installed state by varying these radii. In contrast to the magnetic tape with a rectangular cross section, there are no areas in the magnetic tape according to the invention which are penetrated by field lines of non-optimized length, so that the ratio between adhesive force and cross-sectional area increases. In particular, the shape of the magnetic tape according to the invention eliminates regions between the magnetic poles and on the edges which lie opposite the magnetic poles, these make no or only an insignificant contribution to the magnetic force of the tape.

In the case of magnetic tapes according to the prior art with a rectangular cross section, the aspect ratio is usually in the range of 9: 2 in length and width. In order to achieve a similar relationship with the magnetic tape according to the invention, two or more sheets according to the invention can also be arranged side by side.

To optimize the adhesive force, the distance between the outer and inner contours is chosen to be essentially constant as the wall thickness of the arch, which results in a largely constant wall thickness. In particular, by varying the shape of the sheets, it is possible to specifically influence the length of the field lines for a given magnetic tape thickness in order to optimize the adhesive force.

Further embodiments of the magnetic tape according to the invention can be derived from the shape of the outer and inner contour, the number and the sequence of different shapes of recesses combined on a magnetic tape.

For example, instead of arches with a semicircular outer and inner contour, arcs can also be made elliptical. Other shapes are also possible.

It is also possible to create the contours as mixed shapes and to combine several shapes on a magnetic tape.

The device according to the invention for magnetizing a magnetic tape according to claim 1 is characterized in that two magnetic tapes which lie against one another are magnetized at the same time, this composite being magnetically neutral towards the outside. There is thus no adhesion of the band to iron parts of the magnetization device. The production of such magnetic tapes can therefore be carried out particularly advantageously at a higher speed, with less friction occurring, and less wear and tear also occur.

With this arrangement of two magnetic tapes, the recess between the pole faces in the magnetic tape facing one another and the pole faces of the two magnetic tapes touching, a particularly effective magnetization of the magnetic tape is achieved by a conductor running centrally in the cavity formed by the recesses. According to the known method of pulse magnetization, the two magnetic tapes are magnetized simultaneously.

By using the circular magnetic field forming around a circular conductor for magnetizing the magnetic tape according to the invention with a semicircular arc, a particularly effective alignment of the elementary magnets in the ferromagnetic particles is achieved.

For this purpose, the device for magnetization according to the invention has a recess which corresponds to the outer contour of two adjacent magnetic tapes of the same cross section.

Two magnetic tapes are brought together for magnetization, these then pass through the device and are separated from one another again after leaving.

The drawings explain the invention in detail:

Fig. 1 shows an example of a magnetic tape with two semicircular recesses and a largely uniform wall thickness in an oblique view;

Fig. 2 shows a cross section through a device for magnetizing a magnetic tape.

Here represent:

(1) magnetic tape (2) recess (3) pole face (4) device for magnetization (5) recess (6) conductor (H) magnetic field line.

The drawings are not to be interpreted as restrictive.

In Fig. 1, the magnetic tape (1) according to the invention is shown, which has a contour with at least one axially extending recess (2). The recess (2) is located between the pole faces (3) of the magnetic tape (1).

Furthermore, the wall thickness of the magnetic tape (1) is chosen so that it is largely uniform.

In the present example, the magnetic tape (1) has two cutouts (2) between the pole faces (3). The recesses (2) have the shape of a semicircle.

The simplest case of shaping for the magnetic tape (1) according to the invention is represented by an arc in the form of a half circular ring, the axially created recess (2) being semicircular and the wall thickness being chosen to be constant. The most favorable field line course is achieved in the magnetic tape (1).

In this cross section, in comparison to a rectangular cross section, non-magnetized areas, which are located at the corners and on the side facing away from the pole face (3) and between the pole faces (3), are eliminated.

The adhesive force of the magnetic tape (1) remains at the level of the tape with a rectangular cross section of comparable size.

The magnetic tape (1) according to the invention with cutouts (2) is considerably more flexible compared to a conventional magnetic tape with a rectangular cross section, since the cutouts (2) combined with the cross section adjustment make the tape (1) more flexible with a view to achieving a largely uniform wall thickness , This is associated with advantages that simplify the winding and handling of the magnetic tape (1) during manufacture and further processing. All edges of the magnetic tape (1) are rounded to prevent damage to the sealing profiles during assembly and in continuous use.

Derived forms can be realized in the recesses (2), which have, for example, an elliptical or a rounded rectangular or a combined rectangular semicircular or a rectangular-elliptical recess (2) or one with an arch arrangement in a semicircular or semi-elliptical shape, the wall thickness largely is even. Mixed forms of the mentioned forms are also possible.

One or more cutouts (2) are made in the magnetic tape (1) according to the invention, wherein a plurality of cutouts (2) are spaced parallel to one another. In this case, the recesses (2) can have the same shape or be designed differently.

It is particularly advantageous if the distance from parallel, axially arranged recesses (2) of the magnetic tape (1) is at most 10 mm, since a particularly favorable magnetic field is formed and high magnetic adhesive forces result.

Particularly preferred designs are those with two or three semicircular cutouts (2) spaced apart in parallel, since these spatial shapes are based on commercially available magnetic tapes of the aspect ratio of a rectangle enveloping the magnetic tape cross section of approximately 9: 2 in length and width.

Such an embodiment with two cutouts (2) is shown by way of example in FIG. 1. By selecting the cross-sectional ratios, commercially available tapes can be replaced by the magnetic tapes (1) according to the invention without having to make any changes to the production facilities.

2 shows the magnetization device (4) according to the invention for magnetizing a magnetic tape (1) according to claim 1.

An embodiment is shown which is suitable for the magnetization of the particularly preferred magnetic tape (1) with two semicircular spaced cutouts (2). A preferred embodiment with a semicircular recess (2) in the magnetic tape (1) represents the most favorable condition for the magnetization, since the field lines in the material of the magnetic tape (1) generate the most effective magnetization. The circularly concentric course of the magnetic field lines around a conductor (6) with a circular cross section is used particularly advantageously. Magnetization is particularly effective if the magnetic tape (1) also has a largely uniform wall thickness.

(1) represents the magnetic tape, which is arranged twice in the device (4) according to the invention in a recess (5) adapted to the contour of the magnetic tape (1), the pole faces (3) facing each other, the cutouts (2 ) face each other exactly and the pole faces (3) touch each other. The recesses (2) are arranged in alignment.

Centrally arranged in the cylindrical cavities formed by the semicircular recesses (2) between the two bands (1) are conductors (6), which bring about a particularly effective magnetization of the magnetic tapes (1) according to the known method of pulse magnetization.

The conductors (6) are arranged in the plane of the contacting pole faces (3). The current direction in the two conductors (6) is in opposite directions.

This is indicated in Fig. 2, the current directions are marked in the conductors (6) with a point (ie coming out of the plane) or a cross (ie going into the plane), moreover this is about the conductors ( 6) magnetic field forming a circular cross section in the form of a circular magnetic field line (H).

To carry out the magnetization, two magnetic tapes (1) of the same cross section are brought together with the pole faces (3), between which the recesses (2) lie, and transported into the device (4), the pole faces (3) touching. The strips (1) are positioned relative to one another in such a way that the cutouts (2) are aligned with one another. Then the bands are magnetized. After the bands (1) have been magnetized, they are separated from one another again after they have been transported out of the device (4).

The device according to the invention for magnetization (4) is characterized in that it can be used to magnetize magnetic tapes (1) which, in the proposed arrangement of two magnetic tapes (1), are magnetically neutral towards the outside, so that there is no liability for iron parts of the magnetizing device (4) occurs. It is of particular advantage here that at the points where the pole faces of the two magnetic tapes touch, an arrangement of poles is generated by the magnetization in such a way that the two tapes adhere to one another, since opposite polarities arise in each case.

It is therefore particularly advantageous for such magnetic tapes (1) to be produced at a higher speed, with less friction, and less abrasion and wear.

The magnetic neutrality on the outside of the interconnected magnetic tapes (1) is also advantageous when winding and handling the magnetic tapes (1).

In other embodiments, the devices (4) for magnetizing the magnetic tapes (1) according to the invention have a recess (5) which is matched to the respective contour of the magnetic tape (1), the number of conductors (6) always being the number of recesses in the respective one Magrietbandes (1) corresponds.

- claims -

Claims

claims

1. Polymer magnetic tape (1), consisting of ferromagnetic particles and polymer material, with cutouts in cross section and arrangement of the magnetic poles on one side, characterized in that

the cross section of the magnetic tape has at least one recess (2) between the spaced-apart adjacent pole faces (3) in an axial arrangement, and

-b- the wall thickness of the magnetic tape (1) is largely uniform, whereby

-c- the aspect ratio of a rectangle enveloping the magnetic tape cross section is approximately 9: 2 in length and width, and

-d- the distance between the pole faces (3) is a maximum of 10 mm, whereby

successive pole faces (3) have different magnetic polarities alternately.

2. Polymer magnetic tape (1) according to claim 1, characterized in that two or more axially arranged recesses (2) running in parallel are present.

3. Polymeric magnetic tape (1) according to claim 1, characterized in that the recess (2) is designed in the form of a semicircle or a (semi-) ellipse or a rounded rectangle or a combination of rectangle and circle and / or ellipse.

4. Polymeric magnetic tape (1) according to claim 1, characterized in that the recess (2) is in the form of a mixed form which is derived from the forms mentioned in claim 3.

5. Polymeric magnetic tape (1) according to claim 1, characterized in that a plurality of recesses (2) with combinations of the shapes according to claims 3 and 4 are arranged on the magnetic tape.

6. The device for magnetizing (4) a magnetic tape (1) according to claim 1, characterized in that two magnetic tapes (1) are arranged opposite one another, the at least one axially extending recess (2) being aligned with one another and the pole faces (3 ) touch.

7. Magnetizing device (4) according to claim 6, characterized in that in the plane of the pole faces (3) of the touching magnetic tapes (1) a conductor (6) is arranged centrally to the recesses (2).

8. Magnetizing device (4) according to claim 7, characterized in that the number of conductors (6) is equal to the number of recesses (2) in the magnetic tape (1).

9. The magnetization device (4) according to claim 8, characterized in that the current flow in conductors (6) arranged next to one another runs in opposite directions.

10. The magnetization device (4) according to claim 6, characterized in that no magnetization takes place on the side opposite the recess (2) of the magnetic tape (1).

11. The magnetization device (4) according to claim 6, characterized in that two magnetic tapes (1) of the same cross section are brought together before magnetization, the pole faces (3) touching and being separated from one another after magnetization.