Electrical line and method for manufacturing an electrical line

Abstract

An electrical line has a core and an insulating sheath that is extruded onto the core. A structured surface having a plurality of structural elements stamped into it is formed over the entire surface of the insulating sheath. The stamped structure is a microstructure, wherein the individual structural elements have a stamping depth of at most 0.15 mm.

Claims

1. An electrical line extending in a longitudinal direction, the electrical line comprising: a core; and an insulating sheath extruded onto said core, said insulating sheath having a structure extending in the longitudinal direction and said structure having plurality of structural elements being stamped into said insulating sheath to form a structured surface, said structured surface having a form of an imbricated surface and said structural elements each taking a form of an obliquely positioned imbricated form, wherein a plurality of obliquely positioned imbricated forms taking a form distributed in a peripheral direction.

2. The line according to claim 1, wherein said structure is a microstructure in which individual ones of said structural elements have a stamping depth of less than 0.15 mm.

3. The line according to claim 1, wherein: said structure extends over an entire surface of said insulating sheath; and said structural elements are formed such that they are repeated periodically in the longitudinal direction.

4. The line according to claim 1, wherein said structural elements have hollows, and said hollows cover at least 30% of said structured surface.

5. The line according to claim 1, wherein said structural elements have an extent in at least one of the longitudinal direction or a peripheral direction of at most 0.5 mm.

6. The line according to claim 1, wherein said insulating sheath is made of an insulating material being polyurethane.

7. The line according to claim 1, wherein said insulating sheath is a wire sheath of a wire.

8. The line according to claim 1, wherein said structure is a microstructure in which individual ones of said structural elements have a stamping depth of less than 0.07 mm.

9. The line according to claim 1, wherein said structural elements have hollows, and said hollows cover at least 50% of a surface of said structured surface.

10. The line according to claim 1, wherein said structural elements have an extent in at least one of the longitudinal direction or a peripheral direction of at most 0.3 mm.

11. The line according to claim 1, wherein said structural elements are spaced from one another in at least one of the longitudinal direction or a peripheral direction by at most 0.5 mm.

12. A method for manufacturing an electrical line extending in a longitudinal direction, which comprises the steps of: providing a core; extruding an insulating sheath onto said core; and stamping a structured surface having a plurality of structural elements into the insulating sheath still being soft downstream of an extrusion of the insulating sheath, the structured surface having a form of an imbricated surface and the structural elements each taking a form of an obliquely positioned imbricated form, wherein a plurality of obliquely positioned imbricated forms taking a form distributed in a peripheral direction.

13. The method according to claim 12, which further comprises forming the structured surface by at least one stamping wheel.

14. The method according to claim 12, which further comprises disposing, downstream of an extrusion head, a cooling bath through which the core is guided, and the stamping of the structural elements takes place in the cooling bath.

15. The method according to claim 12, which further comprises forming the structured surface by a plurality of stamping wheels that are disposed offset from one another around a periphery of the insulating sheath.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) An exemplary embodiment will be described in more detail below with reference to the figures. In the latter, in each case in simplified illustrations:

(2) FIG. 1 shows part of a longitudinal sectional illustration of an electrical line in the form of a single wire,

(3) FIG. 2 shows part of a highly simplified plan view of the structured surface of the insulating sheath of the electrical line, according to a first variant, in which the surface takes a form in the manner of a crater landscape,

(4) FIG. 3 shows part of a sectional illustration of the structured surface that is illustrated in FIG. 2,

(5) FIG. 4 shows a second variant embodiment of the structured surface, which takes the form of an imbricated surface,

(6) FIG. 5 shows part of a cross sectional illustration of the imbricated surface that is illustrated in FIG. 4, and

(7) FIG. 6 shows a highly simplified schematic illustration of an extrusion plant for manufacturing the electrical line.

DESCRIPTION OF THE INVENTION

(8) In the figures, equivalent parts are provided with like reference numerals.

(9) The electrical line 2 that is illustrated in FIG. 1 takes the form of an electrical wire that has an electrical conductor, as the core 4, and an insulating sheath 6 that surrounds the latter. The line 2 extends in a longitudinal direction 8. The line 2 is an endless product that is initially not premanufactured and is rolled onto a cable drum, typically with a length of a plurality of hundreds of meters or indeed a plurality of kilometers. It has a nominal external diameter D.

(10) As already indicated in FIG. 1, the insulating sheath 6 generally has a structured surface 10A, 10B. This is a microstructure having a plurality of stamped structural elements 12A, 12B.

(11) Two different preferred variant embodiments of possible structured surfaces 10A, 10B are illustrated in FIGS. 2, 3 and 4, 5 respectively.

(12) The variant embodiment in FIG. 2 is the structured surface 10A in the manner of a crater landscape, wherein the individual structural elements here are formed by individual hollows 12A. These hollows 12A are stamped in the manner of indentations having an approximately hemispherical shape. The hollows 12A each have a stamping depth t that is typically only in the region of 0.05 mm. At the same time, the hollows 12A have an extent a that is preferably approximately 0.1 mm. In the region of the hemispherical hollows 12A, the latter thus have a circular peripheral contour, and the extent a corresponds to the diameter of this peripheral contour. Both in the longitudinal direction 8 and in a peripheral direction 18, mutually adjacent structural elements 12 Are at a spacing d that, in the variant embodiment of FIG. 2, is for example in the region of the extent a or indeed somewhat below this.

(13) In the alternative embodiment according to FIGS. 4 and 5, the surface is formed as an imbricated surface 10B, and the individual structural elements are formed by individual imbricated forms 12B. These too have a stamping depth t preferably in the region of 0.05 mm. The extent a of the individual imbricated forms 12B, in particular in the longitudinal direction 8, is preferably somewhat larger than those of the hollows 12A and is preferably in the region of just a few millimeters. A respective imbricated form 12B has a surface 22 similar to a fish scale that runs in an oblique orientation in respect of the longitudinal direction 8. The highest region of a respective imbricated form 12B, that is to say the segment having the largest diameter, at the same time defines the nominal external diameter D of the electrical line 2. In the longitudinal direction 8, the individual elements 22 similar to a fish scale are directly adjacent to one another, since they themselves, in each case in part-segments, so to speak, create the surface having the nominal external diameter D.

(14) For manufacturing a line 2 of this kind, first a conventional extrusion method is used, as explained in relation to FIG. 6: the core 4 is fed, together with sheath material 24, to an extrusion head 26 such that the insulating sheath 6 is formed downstream of the extrusion head 26. Directly adjacent to the extrusion head 26, typically at a spacing of a few tens of centimeters, for example at a spacing of from 20 cm to 50 cm, a stamping device 30 is arranged for forming the structured surface 10, and this stamping device 30 has in the present case a plurality of stamping wheels 32, in particular two. These are mounted such that they are rotatable about an axis of rotation in the manner of free-running deflection rollers. On their peripheral edge, they conventionally have a convexly curved casing surface having a radius that corresponds to the radius of the insulating sheath 6. Formed on this casing surface are suitable stamping elements, for example in the form of bumps, for forming the hollows 12A.

(15) In the exemplary embodiment that is illustrated in FIG. 6, the stamping device 30 is furthermore arranged in a water or cooling bath 34, which is illustrated by a dashed line. In particular, the stamping wheels 32 are here arranged under water.

(16) For manufacture, the line 2 is pulled through the cooling bath 34 at high take-off speed. During this, the structured surface 10A, 10B that extends over the entire length of the line 2 is continuously formed by the stamping wheels 32. In this case, the structural elements 12A, 12B cover the insulating sheath 6 over its entire surface, preferably also in the peripheral direction 18.

(17) In the variant embodiment of FIG. 6, the two stamping wheels 32 are arranged at the same longitudinal position. As an alternative to this, they may also be arranged at different longitudinal positions, that is to say offset from one another in the longitudinal direction 8. Specifically, it is also possible for more than two stamping wheels 32 to be formed, for example two, three or four stamping wheels, such that the surface is provided with the structural elements 12 As uniformly as possible. The individual stamping wheels 32 are in this case arranged offset from one another in the peripheral direction 18.

LIST OF REFERENCE NUMERALS

(18) 2 Line 4 Core 6 Insulating sheath 8 Longitudinal direction 10A, B Surface 12A Hollow 12B Imbricated form 18 Peripheral direction 22 Surface similar to a fish scale 24 Sheath material 26 Extrusion head 30 Stamping device 32 Stamping wheel 34 Cooling bath a Extent d Spacing D Nominal diameter t Stamping depth