Abstract
A cable having at least one conductor which extends in a longitudinal direction and is enclosed by a jacket that is extruded onto the conductor. The jacket has a plurality of sections which are manufactured from different plastics, with results in the sections having different functionality. As a result, properties of the cable on a respective section are optimally adapted to the requirements of the respective section. There is also described a method for producing such a cable and to an extrusion unit for extruding the jacket with a plurality of sections.
Claims
1. A method for producing a cable, the method comprising: extruding a jacket onto a conductor by way of an extrusion head; forming the jacket with a plurality of portions that are made from dissimilar plastics materials; and feeding each of the dissimilar plastics materials by a respective pressure-controlled feed unit having an adjustable conveying quantity.
2. The method according to claim 1, which comprises completely interrupting a feed of one plastics material at an end of a given portion of the jacket and, while avoiding a formation of a mixed zone, subsequently activating a feed of another plastics material for forming a subsequent portion of the jacket.
3. The method according to claim 1, which comprises feeding the dissimilar plastics materials to the extrusion head in an alternating manner by way of a switching element.
4. The method according to claim 1, which comprises: subjecting a given feed unit to pressure for conveying the plastics material contained in the given feed unit into the extrusion head and extruding the jacket onto the conductor; and subsequently switching between portions by switching off the pressure to the given feed unit and pressurizing another feed unit for conveying another plastics material into the extrusion head.
5. The method according to claim 1, which comprises providing the dissimilar plastics materials in each case by way of a discontinuously operating feed unit.
6. The method according to claim 1, which comprises switching between the feed units in alternation.
7. The method according to claim 1, wherein the feed unit is an injection-molding apparatus or a melt pump, each without an extruder screw.
8. A cable produced according to a method according to claim 1, the cable comprising: at least one conductor extending in a longitudinal direction; and a jacket surrounding said at least one conductor, said jacket being an extrusion jacket extruded onto said at least one conductor and having a plurality of portions made from dissimilar plastics materials.
9. The cable according to claim 8, wherein said plastics materials of two mutually successive portions are not mixed with one another but configure an interface that runs substantially transversely to the longitudinal direction.
10. The cable according to claim 8, wherein at least two of said plastics materials are dissimilar in terms of a hardness thereof.
11. The cable according to claim 8, wherein a plurality of portions are sequentially disposed in the longitudinal direction.
12. The cable according to claim 11, wherein said plurality of portions are alternatively configured as hard portions and soft portions, wherein the soft portions are configured as hinges.
13. The cable according to claim 8, wherein one of said portions is a spring element that extends continuously in the longitudinal direction.
14. The cable according to claim 13, wherein said spring element extends helically along a helix about said conductor.
15. The cable according to claim 13, wherein said spring element is disposed to form a plurality of delimitation elements on an exterior side of said jacket and said delimitation elements pre-define a minimum bending radius of the cable.
16. The cable according to claim 15, wherein one or both of the following is true: said spring element is disposed in an encircling manner, said jacket has a circular cross-section.
17. The cable according to claim 8, which further comprises an exterior jacket surrounding said jacket and covering said jacket outwardly.
18. The cable according to claim 8, wherein said jacket is an exterior jacket.
19. An extrusion unit for carrying out the method according to claim 1, the extrusion unit comprising: an extrusion head for extruding a stranded product; and a plurality of feed units for selectively feeding dissimilar plastics materials, said feed units being pressure-controlled feed units for setting a conveying quantity thereof.
20. The extrusion unit according to claim 19 wherein said extrusion head is configured for extruding a jacket for a cable onto a conductor.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0049] FIG. 1 shows a cable in a side view;
[0050] FIG. 2 shows the cable according to FIG. 1 in a cross-sectional view taken along the line I-I in FIG. 1;
[0051] FIG. 3 shows a further cable in a cross-sectional view;
[0052] FIG. 4 shows a further cable in a side view;
[0053] FIG. 5 shows the cable according to FIG. 4 in a cross-sectional view taken along the line II-II in FIG. 4;
[0054] FIG. 6 shows the cable according to FIG. 4 in a bent state, in a side view;
[0055] FIG. 7 shows a further cable which is configured as an audio cable;
[0056] FIG. 8 shows a further cable which is installed passing through an environment having specific requirements set for the jacket;
[0057] FIG. 9 shows a further cable which is installed in the environment of a component;
[0058] FIG. 10 shows an extrusion unit for strip-extruding a helical portion;
[0059] and
[0060] FIG. 11 shows a further extrusion unit having pressure-controlled feed units and a switching element.
DETAILED DESCRIPTION OF THE INVENTION
[0061] Referring now to the figures of the drawing in detail, various exemplary embodiments of a cable 2 which extends in a longitudinal direction L and has a conductor 4 which is surrounded by a jacket 6 are illustrated in FIGS. 1 to 9. The jacket 6 has a plurality of portions 8, 10, 12 which are made from dissimilar plastics materials and which are extruded onto the conductor 4.
[0062] With reference to FIG. 1, there is shown a first exemplary embodiment of the cable 2 in a side view. The embodiment has a total of two portions 8, 10 from dissimilar plastics materials, wherein the one portion 10 as a spring element 13 is produced from one plastics material which is harder than the plastics material used for configuring the other portion 8. The softer plastics material in this instance forms a first portion 8 in which the harder plastics material is embedded as the second portion 10. In the exemplary embodiment shown here, the second portion 10, that is to say presently the spring element 13, is moreover configured in the manner of a helix and in the shape of a helix extends about the conductor 4 and in the longitudinal direction L. On account thereof, the second portion 10 is configured in the manner of a coiled spring having a corresponding spring effect, on account of which the bending elasticity of the entire cable 2 is then set in such a manner that entangling or interlacing of the cable 2 is prevented. A particularly effective entanglement protection is implemented in this instance by the combination of a hard and a soft plastics material.
[0063] FIG. 2 shows the cable 2 according to FIG. 1 in a cross-sectional view taken along the line I-I in FIG. 1. The centrally routed conductor 4 and the jacket 6 which completely surrounds the conductor 4 can be clearly seen here. The first portion 8 composed of the softer plastics material here configures an in particular circular cross section of the jacket 6 in which the spring element 13 is embedded. Furthermore, the variant of the cable 2 shown in FIGS. 1 and 2 has an external jacket 14 which is additionally extruded onto the jacket 6 and completely covers the latter.
[0064] The second portion 10 as the spring element 13 in FIG. 2 is embodied having a round cross section; however, other design embodiments are also conceivable, for example the strip-shaped design embodiment illustrated in FIG. 3. The variant of the cable 2 shown in FIG. 3 is moreover configured without an additional external jacket 14 such that the jacket 6 by way of the portions 8, 10 is per se the external jacket 14 of the cable 2.
[0065] FIG. 4 shows a further variant of the cable 2 in a side view, wherein the second portion 10 which here is configured as the spring element 13 is not completely integrated in the jacket 6 but is constructed on the remaining jacket, that is to say presently on the first portion 8, and herein projects at a height H, measured perpendicularly to the longitudinal direction L. In this way, the second portion 10 configures as a delimitation element 16 that encircles the cable 2 and guarantees a corresponding reinforcement of the cable 2.
[0066] The variant of the cable 2 according to FIG. 4 is illustrated in FIG. 5 in a sectional view, the section being taken along the plane II-II indicated in FIG. 4. The helically encircling second portion 10 and the cross section thereof, presently a triangular cross section, that is constructed in an outward manner on the first portion 8 can be clearly seen herein.
[0067] The reinforcing effect of this delimitation element 16 becomes particularly evident in FIG. 6 which shows the cable from FIG. 4 in a flexed illustration. A minimum bending radius B of the cable 2 herein is predefined by the delimitation element 16, said minimum bending radius B being highlighted as an arrow in FIG. 4. The delimitation of the bending radius B is initially achieved in particular in that the delimitation element 16 in the bent state prevents the cable 2 from being excessively flexed. In the extreme case, the dissimilar portions of the delimitation element 16 contact one another and on account thereof prevent further flexing. In a variant (not shown) an in particular soft jacket in which the delimitation elements 16 are then enclosed or integrated is additionally applied.
[0068] In principle, it is also possible for a plurality of delimitation elements to be configured in particular as a plurality of not interconnected portions 10 of the jacket 6. In a variant (not shown) a plurality of spring elements 13 are configured in the manner of a helix, for example, said spring elements 13 in this instance in a corresponding manner also configuring a plurality of delimitation elements 16.
[0069] FIG. 7 shows a further variant of the cable 2 which presently is configured in particular as an audio or headphone cable. As opposed to the aforementioned variants of the cable 2 having portions 8, 10 that are continuous in the longitudinal direction L, the cable 2 in FIG. 7 has a plurality of portions 8, 10 that are sequentially disposed in the longitudinal direction L and are made from dissimilar plastics materials. The jacket 6 of the cable 2 illustrated here is configured in particular from two dissimilar plastics materials which in an alternating manner are successively disposed in the longitudinal direction L. The first portions 8 in the variant shown here are in each case made from a soft plastics material and in this instance form hinges of the cable 2 where the latter can be bent. By contrast, the second portions 10 that are made from a hard plastics material form in each case longitudinal portions which in comparison to the first portions 8 are flexurally rigid and which correspondingly cannot be bent. A particularly ordered folding-up of the cable 2 is enabled, and entangling or interlacing is prevented in this way.
[0070] FIG. 8 shows a cable 2 having a plurality of portions 8, 10, 12 which in the longitudinal direction L have been extruded sequentially onto a conductor 4 (not illustrated in more detail). The cable 2 is to be installed in portions in an environment U which sets particular requirements for the jacket 6 of the cable 2. However, there are no special requirements outside this environment U. Such requirements are, for example, a particular electrical shielding of the cable 2 in order to avoid any electromagnetic radiation into the environment U or from the latter into the cable 2, or else a particular media resistance should the environment U contain aggressive substances such as, for example, acids. Alternatively, a particularly high temperature prevails in the environment U such that the cable in the portion 8 that is routed through the environment U is to be particularly temperature-resistant. The respective first portion 8 is therefore made from a correspondingly suitable plastics material which has been selected taking into account the requirements. By contrast, the portions 12 that are outside the environment U are made from another plastics material which does not have to meet the respective requirements and therefore is expediently selected with a view to other criteria.
[0071] Additionally, the first portion 8 in FIG. 8 is bordered by two second portions 10 which are disposed in the transition region toward the environment U and are made from sealing plastics materials, for example, should the environment U be in particular encapsulated. In this way, the jacket 6 of the cable 2 shown in FIG. 8 is selectively adapted in an optimal manner to the respective requirements that apply in each case to a specific portion 8, 10, 12. The plastics materials used in each case for configuring the dissimilar portions 8, 10, 12 are selected in a manner corresponding to the requirements that apply to the respective portion 8, 10, 12.
[0072] A cable 2 having a plurality of successive portions 8, 10 in the longitudinal direction L is shown in FIG. 9, wherein the cable 2 is to be installed so as to bypass a component K which sets particular requirements for the portion 8 of the cable 2. For example, the component K is a motor of a motor vehicle (not illustrated in more detail) and the portion 8 is to be particularly heat-resistant. Said portion 8 is therefore made from a correspondingly heat-resistant plastics material, whereas the portion 10 that adjoins the portion 8 in the longitudinal direction L are made from a comparatively more cost-effective plastics material which does not need to be heat-resistant.
[0073] FIGS. 8 and 9 show only two of the multiplicity of potential exemplary embodiments of the cable 2. In very general terms, the cable 2 comprises a plurality of portions 8, 10, 12 which are disposed sequentially in the longitudinal direction L, wherein the plastics material used in each case for the configuration of said portions 8, 10, 12 is selected with a view to the requirements that are set for the respective portion 8, 10, 12, that is to say with a view to specific main properties of the plastics material. The requirements herein can be in particular physical, chemical, electrical, or mechanical requirements such that a respective plastics material in a corresponding manner can be distinguished by specific chemical, physical, electrical or mechanical properties.
[0074] An extrusion unit 18 for producing the cable 2 is shown in each of FIGS. 10 and 11. In each case one conductor 4 onto which a jacket 6 is then extruded is fed in each case to the extrusion unit 18 herein. The cable 2 is in particular continuously conveyed in a conveying direction F such that the jacket 6 is also applied preferably continuously and in particular also universally.
[0075] The extrusion unit 18 shown in FIG. 10 serves for configuring a jacket 6 having a plurality of portions 8, 10, wherein the latter are in each case configured continuously and universally. The cable 2 produced in FIG. 10 herein corresponds in particular to the exemplary embodiment already shown in FIG. 1. The extrusion unit 18 for applying the jacket 6 comprises an extrusion head 20 to which a first plastics material is fed in order for the first portion 8 to be configured. The second portion 10 is configured by means of a strip-extrusion head 22 which in the variant shown here is integrated in the extrusion head 20. The strip-extrusion head 22 in operation continuously rotates about the longitudinal axis L in order for the helical shape of the second portion 10 to be configured.
[0076] A second extrusion unit 18 which is particularly suitable for continuously configuring a plurality of portions 8, 10 that are sequentially disposed in the longitudinal direction L is illustrated in FIG. 11. In contrast to the extrusion unit 18 of FIG. 10, the extrusion of the various plastics materials herein is not performed continuously but in an alternating and selective manner. To this end the extrusion unit 18 comprises a switching element 24 in order to in each case feed one or some of the plurality of plastics materials to the extrusion head 20. This switching element 24 is presently embodied as a branch having a non-return flap 26 which in a respective position feeds in each case only one of the plastics materials to the extrusion head 20. On account of this particular design embodiment of the switching element 24 as a branch having a non-return flap 26, any mixing of the dissimilar plastics materials during the extrusion is prevented in a particularly efficient manner.
[0077] In the case of the extrusion unit 18 of FIG. 11, the material feed is performed by a plurality of feed units 28 which presently are configured as pressure-controlled injection-molding apparatuses. In a variant (not shown) a respective one of the feed units 28 is alternatively a melt pump or an extruder. In this way, the conveyed quantity of a respective feed unit 28 is capable of being metered in a particularly precise manner and is set according to requirements. Depending on the position of the non-return flap 26, that is to say in general depending on the configuration of the switching element 24, the feed unit 28 connected to the extrusion head 20 in a corresponding manner is impinged with a corresponding pressure such that the plastics material that is contained in this feed unit 28 is conveyed into the extrusion head 20 and as the jacket 6 is extruded onto the conductor 4. In switching, the pressure of the one feed unit 28 is then switched off in a corresponding manner such that smooth switching of the switching element 24 is possible. In order for the other plastics material to be conveyed, the other feed unit 28 is then impinged with pressure in a corresponding manner. In this way, particularly clearly defined interfaces 30 are configured along the cable 2 between two successive portions 8, 10. The formation of a mixed zone is particularly avoided on account thereof.
