HK1130560B - Flexible magnetization energy transfer ribbons and process for producing them - Google Patents

Abstract

A flexible energy transfer ribbon, comprising a magnetized strip (3) consisting of an elastomer material forming a matrix in which particles are embedded, communicating permanent magnetization oriented in the thickness direction of said strip thereto, at least one energy transfer member (2) extending along the support strip, and a coating material (1) in which the or each energy transfer member is embedded and adhering to the magnetized strip. It is noteworthy in that the magnetized strip is subdivided into successive sections (31) of lengths such that dimensional change effects induced in the magnetized strip especially through the effect of temperature differences induce, between the magnetized strip and the coating material, stresses that are low enough to prevent the adhesion between said magnetized strip and said coating material from weakening. Application in particular to optical links or low-current electrical links between means of equipment that can move relative to one another, especially rotating equipment.

Description

The present invention relates to a flexible energy transfer band, comprising a flexible longitudinal support band, with permanent magnetisation, and at least one flexible longitudinal energy transfer organ, held by the said band at least against any relative transverse displacement.

A flexible tape, with or without permanent magnetization, is frequently used in many technical fields and in various embodiments to transfer energy (including of course signals) between the respective localised areas of two solids moving relative to each other.

Different flexible tape structures and possible applications are described in detail in the preamble and description of the document WO 2005/083724 A1 on behalf of the applicant, which will be referred to as necessary.

The use of such known flexible tapes is of great interest in many applications, as mentioned in the above document.

A particular example of such a tape consists of a series of energy transfer organs immersed in a mass of a fixing agent such as a resin, the resulting assembly being fixed on one side of a supporting tape made for example of an elastomeric material charged with magnetic particles.

It appears that the behaviour of such a tape in the face of temperature differences poses problems.

More specifically, it appears that when the assembly of energy transfer organs embedded in the resin mass can detach from the supporting band, under the action of stresses, mainly shear, appearing between the two. More specifically, it is thought that when the material of the supporting band, typically made of an elastomer of the EPDM type (Ethylene Propylene Diene Rubber in English terminology) incorporating ferrite grains, is exposed to high temperatures of the order of 50 to 80 °C, the molecules of this material rearrange themselves to form a significant, irreversible backstop.

The present invention aims to overcome these disadvantages of the state of the art and to propose a new magnetic band support tape for energy transfer organs or other types of connections which avoids this problematic behaviour while maintaining similar materials and manufacturing processes, and thus without burdening the cost of the tape.

For this purpose, a flexible energy transfer tape is proposed as claim 1.

A second aspect of the invention is a flexible energy transfer tape as claimed 2.

Some preferred but not limited aspects of these ribbons are defined below: * the coating material is an organic resin.* the coating material adheres directly to the magnetic strip or is bonded to the magnetic strip by an adhesive.* the magnetic strip consists of a matrix of ethylene propylene diene (EPDM) rubber in which ferrite grains are immersed.* the tape contains a magnetic layer on either side of the coating material housing the transfer organ (s).* the sections of a magnetic strip are offset from the sections of the magnetic strip (3) so that their opposite sections do not coincide.* the intersections are approximately 3 to 15 mm long, preferably between about 4 and 7 mm.

Finally, a third aspect of the invention proposes a process for the manufacture of a flexible energy transfer tape, characterized by the following steps: provide for a continuous magnetic strip consisting of a matrix-forming elastomeric material into which particles are immersed giving it permanent magnetisation oriented in the direction of the thickness of the magnetic strip,fix along the magnetic strip at least one energy transfer organ with a coating material in which the energy transfer organ or organs are immersed and adhering to the magnetic strip,properly apply in the magnetic strip notches forming rupture grooves spaced at distances such as dimensional change phenomena induced in the magnetic strip,in particular induce the effect of under-adhesion differences between the magnetic strip and the material of the magnetic strip, which are sufficiently strong to cause rupture of the magnetic strip and sufficiently weak to prevent fractures between the magnetic strip and the matrix.

The advantage of this method is that it involves a further step of simultaneous exposure of the assembly to a temperature leading to a change in dimension and to bending stresses, so as to transform the said gaps forming break-off bearings into breaks separating the sections.

Other aspects, purposes and advantages of the present invention will be better illustrated by reading the following detailed description of preferred embodiments of the present invention, given as a non-limiting example and made by reference to the attached drawings, on which: Figure 1 is a cross-sectional view of a ribbon in a first embodiment of the invention,Figure 2 is a longitudinal view of the ribbon in Figure 1, showing the I-I cut line used for Figure 1,Figure 3 is a cross-sectional view of a ribbon in a second embodiment of the invention, andFigure 4 is a longitudinal view of the ribbon in Figure 1, showing the III-III cut line used for Figure 3, and

Figures 5A to 5C illustrate in longitudinal sections the various steps of an example of a tape manufacturing process according to the invention.

Firstly, with reference to Figures 1 and 2, a ribbon according to the invention has a generally rectangular cross-section, the width (measured horizontally in Figure 1) of which is greater than the thickness (measured vertically in the same figure).

The ribbon thus has a favourable direction of bending, in a longitudinal plane perpendicular to its large faces.

The tape of the invention has a supporting band 3 with permanent magnetization in the direction of its thickness, which may be the same direction over the entire width, which is preferable if the width is relatively small, for example, on the order of less than one to two or three millimetres, but it may also have alternating directions distributed over the width, which may be preferable for larger widths.

The tape also comprises a plurality of energy transfer organs 2 immersed in a common mass 1 of coating material consisting for example of organic resin such as an acrylic resin polymerized with ultraviolet.

The energy transferred by means of the transfer organs 2 can be chosen from a group comprising the energies of light, electric, pneumatic, hydraulic, cableway nature.

In any case, the tradesman may choose from among various practical ways of making tape 1 available to him in order to ensure the desired permanent magnetisation.

Band 3 is for example a rubber matrix of ethylene propylene diene (EPDM) in which ferrite grains are immersed.

Energy transfer organs such as optical fibres may be of conventional construction provided that their permissible bending is compatible with the intended applications of the tape.

For further details on the possible achievements, see WO 2005/083724 A1 cited above.

Figure 1 illustrates the case of a tape according to the invention with four optical fibres 2 arranged side by side in coating material 1 combined with a single magnetic strip 3.

The thickness of coating material 1 shall be chosen to be greater than the outer diameter of each of the organs 2 in order to preserve the continuity of this material 1 along the face of the tape opposite to strip 3 and along the face of the tape on the side of strip 3.

According to an essential aspect of the present invention, and as shown in Figure 2, the support strip 3 is periodically interrupted locally, thus consisting of a succession of magnetic sections 31 separated from each other.

Thus, when a phenomenon of dimensional change, temporary or permanent, occurs relatively between the support band 3 and the coating material 1, shear forces are generated between the two materials that are insufficient to result in a detachment between the two.

In fact, at each break between the individual sections 31 such stresses are released since there is only coating material 1 left, apart from the organs 2 themselves.

Figures 3 and 4 illustrate a second embodiment of the invention wherein the support strip 3 is divided into two support strips 3, 4 on either side of the coating material 1 ribbon housing the organs 2, here five.

In the same way as before, each support strip 3, 4 is broken up to form individual sections 31, 41 respectively. The advantage is that these break-offs are offset from each other by a distance Δ (see Figure 4) of such material that the break-offs between sections on one side do not coincide with the break-offs between sections on the other side, and preferably that a break between two sections on a strip is located significantly to the right of the middle of a section, in the longitudinal direction of the strip, on the opposite side of the strip.

In addition, such a double-support band arrangement improves the behaviour of the tape, as the magnetization level is substantially the same on both sides.

An example of a tape manufacturing process according to the invention is now described in reference to Figures 5A to 5C.

First, a set of organs 2 coated in their coating material 1 is prepared to form a ribbon (Figure 5A).

A continuous magnetic support strip 3 consisting of EPDM loaded with ferrite grains, as shown above, is then glued along this tape (either directly in an adhesive state of material 1 or by means of a separate adhesive).

The next step is to use a knife or similar device to make E-notches in the thickness of strip 3, or preferably only in a substantial part of the thickness, so as not to injure the coating material 1 containing the organs 2 (Figure 5C).

These incisions, which create as many break-off points in the supporting band, are preferably separated by a distance of 3 to 15 mm, preferably around 4 to 7 mm.

The next step is to expose the assembly thus obtained to a temperature of 60 to 80°C for about 2 to 4 hours and at the same time to subject it to bending stresses close to those encountered by the tape in service, so as to cause the EPDM constituting the support strip 3 to contract. This retention can reach about 10%, and it is understood that the cut areas will thus widen to about 0.5 mm wide, and thus separate the individual sections 31 of the strip (Figure 5d).

Since this restraint is permanent, further exposure of the tape to high temperatures in use will not cause any stresses on the tape, which may cause the assembly 1,2 to detach from the 31 sections together forming the supporting tape.

The above process can be easily applied by the craftsman to the manufacture of a tape as shown in Figures 3 and 4.

It is clear that many variants can also be considered without going beyond the scope of the present invention.

In particular, the support strip (s) may be subdivided into sections according to any pattern, whether regular or irregular, including in the direction of the width of the strip where the width of the strip is such that dimensional changes in this direction may be inconvenient.

In addition, the invention applies as soon as any cause is likely to induce stresses between the supporting band (or bands) and the coating material.

Claims (17)

1. A flexible energy-transfer ribbon comprising a magnetized tape (3) formed with an elastomeric material forming a matrix in which are embedded particles which impart to it a permanent magnetism oriented in the direction of the thickness of said tape, at least one energy-transfer device (2) extending along the support-forming magnetized tape (3), and a coating material (1) in which the or each energy-transfer device is embedded and which adheres to the magnetized tape, characterized in that the magnetized tape is subdivided into successive sections (31) of such lengths that dimensional change phenomena induced in the magnetized tape, notably under the effect of temperature differences, induce sufficiently small stresses between the magnetized tape and the coating material for preventing weakening of the adhesion between said magnetized tape and said coating material.
2. A flexible energy-transfer ribbon, comprising a magnetized tape (3) formed with an elastomeric material forming a matrix in which are embedded particles that impart to it a permanent magnetism oriented in the direction of the thickness of said tape, at least one energy-transfer device (2) extending along the support-forming magnetized tape, and a coating material (1) in which the or each energy-transfer device is embedded and which adheres to the magnetized tape, characterized in that the magnetized tape is a continuous magnetized tape (3) in which are formed points of weakness (E) spaced at distances such that dimensional change phenomena induced in the magnetized tape, notably under the effect of temperature differences induce sufficiently strong stresses between the magnetized tape and the coating material for causing separation of the magnetized tape at said points of weakness and formation of tape sections (31), but which are sufficiently small for preventing weakening of the adhesion between said magnetized tape and said coating material.
3. The flexible ribbon according to claim 1 or 2, characterized in that the coating material (1) is an organic resin.
4. The ribbon according to any of claims 1 to 3, characterized in that the coating material (1) adheres directly to the magnetized tape.
5. The ribbon according to one of claims 1 to 3, characterized in that the coating material (1) is firmly attached to the magnetized tape by means of an adhesive.
6. The ribbon according to one of claims 1 to 5, characterized in that the magnetized tape (3) is formed with a matrix of ethylene propylene diene monomer (EPDM) rubber in which ferrite grains are embedded.
7. The ribbon according to one of claims 1 to 6, characterized in that it includes a magnetized tape (3, 4) on either side of the coating material enclosing the transfer device(s).
8. The ribbon according to claim 7, characterized in that the sections (31) of one magnetized tape (3) are offset relatively to the sections (41) of the opposite magnetized tape (3), so that their respective breaks do not coincide.
9. The ribbon according to any of claims 1 to 8, characterized in that the sections (31, 41) have a length comprised between about 3 mm and about 15 mm, and preferentially between about 4 mm and about 7 mm.
10. A method for manufacturing a flexible energy-transfer ribbon, characterized in that it comprises the following steps:

    - providing a continuous magnetized tape (3) formed with an elastomeric material forming a matrix in which are embedded particles which impart to it a permanent magnetism oriented in the direction of the thickness of said tape,

    - fixing along said tape at least one energy-transfer device (2) by means of a coating material (1) in which the or each energy-transfer device is embedded and which adheres to the magnetized tape,

    - making in said magnetized tape notches (E) forming points of weakness spaced at distances such that dimensional change phenomena induced in the magnetized tape, notably under the effect of temperature differences, induce sufficiently strong stresses between the magnetized tape and the coating material for causing rupture of the tape at said points of weakness and formation of tape sections (31), but which are sufficiently small for preventing weakening of the adhesion between said magnetized tape and said coating material.
11. The method according to claim 10, characterized in that the coating material (1) is an organic resin.
12. The method according to either of claims 10 and 11, characterized in that the coating material (1) directly adheres to the magnetized tape.
13. The method according to any of claims 10 to 12, characterized in that the coating material (1) is firmly attached to the magnetized tape by means of an adhesive.
14. The method according to one of claims 10 to 13, characterized in that the magnetized tape (3) is formed with a matrix of ethylene propylene diene monomer (EPDM) rubber in which ferrite grains are embedded.
15. The method according to any of claims 10 to 14, characterized in that it also comprises the fixing of another magnetized tape (4) to the coating material, on the side opposite to the first magnetized tape, with notches forming points of weakness also being made in said other magnetized tape.
16. The method according to any of claims 10 to 15, characterized in that the sections (31, 41) have a length comprised between about 3 mm and about 15 mm, and preferentially between about 4 mm and about 7 mm.
17. The method according to any of claims 10 to 16, characterized in that it comprises a subsequent step that consists of exposing the assembly simultaneously to a temperature leading to a dimensional-change phenomenon and to flexural stresses, so as to convert said notches (E) forming points of weakness into breaks separating the sections (31; 31, 41).