Method for producing an electrical line, tool mould for such a method, and line

Abstract

A process produces an electrical line which extends in the longitudinal direction and the line has a line core and an outer shell. In a continuous shaping process, individual shell portions of the outer shell are formed successively by surrounding the line core with a curable plastic substance. In at least one portion, the outer shell is produced having a cross-sectional geometry which can be varied in the longitudinal direction of the line.

Claims

1. A process for producing a line extending in a line longitudinal direction and having a line core and an outer shell surrounding the line core, which comprises the steps of: forming the outer shell from individual shell sections directly adjoining one another, the individual shell sections of the outer shell being formed, in a continuous molding process by a tool mold, in successive fashion by virtue of the line core being surrounded with a solidifiable plastics compound, said tool mold formed of at least two parts divided along a dividing plane, wherein, in at least one subsection, the outer shell is produced with a varying cross-sectional geometry varying in the line longitudinal direction; forming the outer shell with the subsection having the varying cross-sectional geometry by introducing the solidifiable plastics compound into the tool mold, the tool mold having at least one molding module having a molding cavity with a cross-sectional geometry varying in the line longitudinal direction to form the subsection with the varying cross-sectional geometry; producing the outer shell by means of the tool mold in a modified extrusion process, wherein the molding module serves in an extrusion step as an extrusion nozzle and second in a subsequent end step the molding module serves as a casting mold; during the extrusion step, guiding the line core continuously through the molding module and a further subsection of the outer shell with an uniform cross-sectional geometry is extruded onto the line core; and during the subsequent end step, a feeding of the line core is interrupted and the line core remains within the molding module and the solidifiable plastics compound introduced therein solidifies in the molding module.

2. The process according to claim 1, which further comprises: forming the molding module from multiple parts that are divisible from each other; and separating the molding module after a hardening process, and the line core provided with the outer shell is removed from the molding module.

3. The process according to claim 1, wherein the molding module is temperature-controlled, and, in the extrusion step, the solidifiable plastics compound is kept in a flowable state, and in the end step, the molding module is actively cooled.

4. The process according to claim 1, which further comprises: positioning upstream of the molding module, an extrusion mandrel, through which in turn the line core is guided, and wherein the extrusion mandrel is received in a material distributor so as to form an annular hollow chamber via which the solidifiable plastics compound is fed.

5. The process according to claim 1, which further comprises positioning a cooling module downstream of the molding module, by the cooling module cooling of the solidifiable plastics compound applied to the line core is realized.

6. The process according to claim 5, wherein the cooling module is thermally insulated with respect to the molding module, and the cooling module and the molding module are temperature-controlled differently at least during the extrusion step.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 is a diagrammatic, perspective view of an electrical line as per a first design variant according to the invention;

(2) FIG. 2 is a perspective view of the electrical line as per a second design variant;

(3) FIG. 3A is a highly simplified schematic illustration of a first continuous molding process in a first view;

(4) FIG. 3B is a schematic illustration showing the first molding process as per FIG. 3A in a second view;

(5) FIG. 3C is a perspective view of a variant of the molding process as per FIG. 3A;

(6) FIG. 3D is an exploded, perspective view of the arrangement of FIG. 3C;

(7) FIG. 4 is a schematic illustration showing a first refinement of the first molding process;

(8) FIG. 5 is a schematic illustration showing a second refinement of the first molding process;

(9) FIG. 6 is a schematic illustration showing an alternative second molding process;

(10) FIG. 7 is a perspective view showing a tool mold for the second molding process as per FIG. 6; and

(11) FIG. 8 is side view of an electrical line as per a third design variant.

DETAILED DESCRIPTION OF THE INVENTION

(12) Referring now to the figures of the drawings in detail and first, particularly to FIGS. 1 and 2 thereof, there is shown electrical lines 2 which extend in each case in a line longitudinal direction 4 and contain a line core 6 which is surrounded by an outer shell 8. The outer shell 8 is in this case formed from individual shell sections 10 which directly adjoin one another. In the fully manufactured state, owing to the special molding process to be described below, the shell sections 10 are not individually distinguishable, that is to say the points at which the individual shell sections 10 adjoin one another are not recognizable.

(13) The outer shell 8 is a protective or insulating shell which is generally formed from a hardenable plastics polymer compound. The line core 6 involves one or more electrical conductor wires 12 which are present for example in the form of bundled individual wires or else in the form of coaxial lines etc. The line core 6 may also have a complex construction composed of different line components. Here, it is also possible for optical transmission fibers and/or other components to be integrated into the line core 6. The line core 6 however preferably involves exclusively electrical conductor wires 12 which have in each case one electrical conductor surrounded by an insulator.

(14) The electrical lines 2 are preferably flexible, that is to say non-dimensionally-stable lines, such as are used for example as connection cables for a wide variety of technical appliances, in particular in the field of entertainment electronics.

(15) The electrical line 2 illustrated in FIG. 1 has two special subsections 14 in which the outer shell 8 has a changed cross-sectional geometry in relation to the other shell sections 10. Here, in a central position, there is formed a sealing bush 16, which is thus a direct part of the outer shell 8. Finally, in an end region on the left-hand side, a plug housing 18 is molded as a direct part of the outer shell 8. The sealing bush 16 extends in this case in a radial direction proceeding from a basic form of the outer shell 8. Here, it is commonly the case that the outer shell 8 widens to a radial end diameter which amounts to several times the normal diameter. In the exemplary embodiment, the sealing bush 16 contains an encircling annular groove. Furthermore, in the exemplary embodiment, it is provided that the sealing bush 16, at one end side thereof, extends approximately perpendicular to the line longitudinal direction 4 in the manner of a closure plate. The sealing bush 16 has for example a circular cross-sectional contour, or alternatively a rectangular cross-sectional contour.

(16) In the same way, it is also provided in the case of the plug housing 18 that the latter optionally has a circular or else a rectangular cross-sectional contour which projects in a radial direction beyond the base cross section of the outer shell 8. In principle, however, substantially any desired cross-sectional contour can be realized. Furthermore, undercuts are also possible. Here, in the exemplary embodiment of FIG. 1, an abrupt change and thus cross-sectional step is provided at the start of the plug housing 18.

(17) FIG. 2 shows, as an exemplary embodiment of the electrical line 2, an earphone cable with integrated in-ear earphone 20. The in-ear earphone 20 is in this case also directly jointly integrated into the outer shell 8, wherein, for this purpose, the outer shell widens conically in the end region toward the in-ear earphone 20. A conically widening end piece of the outer shell 8 is likewise formed at the opposite end, from which end piece a plug element 22 emerges. The continuous molding process will be discussed in more detail below on the basis of FIGS. 3A and 3B.

(18) For the production of the electrical line 2, use is made of a modular tool mold 24 which has multiple molding modules 26 which directly follow one another in a line. For the feed of the line core, the tool mold 24 illustrated here contains a feed opening 27A via which, during the process, the line core 6 is guided into the tool mold 24 in successive or continuous fashion. Furthermore, the tool mold shown in FIGS. 3A and 3B also contains an exit opening 27B via which the line core 6 can be led out of the tool mold 24.

(19) The individual molding modules 26 are formed in the manner of conventional tool molds and are for example divided in the center along a dividing plane. Each molding module 26 has at least one gate slot 28 which extends in a conveying direction 36 and which can be seen particularly clearly in the plan view shown in FIG. 3B. A plastics compound 30 which is present in the form of a melt is introduced via the respective gate slot 28. This is realized by an injection unit 32 which injects the compound 30 into the respective molding module 26 at a respective injection point 34. Here, the injection point 34 is guided along the gate slot 28 in continuous fashion.

(20) During the molding process, the individual molding modules 26 are guided in a conveying direction 36 past the in particular static injection point 34. In the exemplary embodiment, the individual molding modules 26 are in a linear in-line arrangement. In an alternative preferred refinement, the individual molding modules 26 are arranged adjacent to one another in a circle, such that they are thus guided repeatedly along a circular path past the injection point 34. In a combination, it is also possible for a linear endless manufacturing arrangement to be realized by virtue of multiple molding modules 26 being arranged in linear fashion and the in each case final molding module 26 in the row being placed in front of the first molding module 26 of the row by a suitable mechanism in repeating fashion. This process is particularly suitable for the endless manufacture of initially straight lines 2.

(21) Within the individual molding modules 26, mold cavities 38 are defined by the free internal hollow space, which mold cavities thus specify and define the shape of the outer shell 8 to be formed. Here, by the modular construction, it is made possible to provide different mold cavities 38 in order to form different cross-sectional geometries for the individual shell sections 10.

(22) In the highly simplified example of FIGS. 3A and 3B, the two outer molding modules 26 each have molding cavities 38 with a conically widening shape. The left-hand one of the two central molding modules 26 has a molding cavity 38 with a normal, circular cross-sectional geometry without a radial widening. Finally, the molding module 26 that adjoins the aforementioned molding module to the right has a rib structure for forming radially outwardly projecting ribs 40.

(23) In the simplified illustration as per FIGS. 3A and 3B, the line core 6 which is introduced into the modular tool mold 24 before the feed of the compound 30 is not illustrated. The exemplary embodiment involves a tool mold which is closed off on both sides, such that the final cable that is produced is thus already produced with a defined length. As an alternative to this, in particular in the case of a circular arrangement of the individual molding modules 26, continuous production of an endless line is also made possible, in the case of which endless line the special shell sections 10 are formed repeatedly in periodically repeating length sections. This is advantageous in particular for the production of standard cables which are for example retroactively provided in a desired manufacturing length by being cut to size.

(24) During the production process, the gate slots 28 of the individual molding modules 26 are guided in successive fashion past the injection point 34, and the compound 30 is introduced by the respective gate slot 28 until the respective molding module 26 has been filled. Subsequently, the next molding module 26 is filled, such that continuous filling of the internal hollow space, formed by the individual molding modules 26, of the modular tool mold 24 is thus realized. Here, the compound 30 hardens already in the molding modules 26 that are filled first, such that the individual sections of the line 2 can be removed in successive fashion after opening of the respective molding modules 26. A strand-like entity is thus removed in continuous fashion from the modular tool mold 24.

(25) For further illustration of a suitable refinement of the process, FIGS. 3C and 3D show a variant of the arrangement of FIGS. 3A and 3B in a perspective illustration. Here, FIG. 3D shows the arrangement from FIG. 3A in an exploded illustration. It is possible to clearly see the multiple molding modules 26, which in this case are arranged in a module cage 41 and one behind the other with respect to the longitudinal axis L. Furthermore, for the alignment of the molding modules 26, a number of alignment elements 43 is guided in the longitudinal direction L through the module cage 41. The molding modules 26 then each have corresponding leadthroughs through which the alignment elements 43 are guided. At the lower end of the stack of molding modules 26 there is arranged a closure plate 45 on which a suitable contact pressure is exerted in order to position the molding elements 26 firmly against one another and eliminate or reduce gaps between the molding elements 26.

(26) For further illustration, FIG. 4 schematically illustrates a first exemplary embodiment of the above-described process. The tool mold 24 has in this case multiple molding modules 26 which are divisible in each case into two halves 26A, 26B. In the exemplary embodiment shown here, three molding modules 26 are arranged in a row, that is to say linearly, wherein two injection points 34 are positioned at the central molding module 26. To prevent the compound 30 from spilling out of that region of the gate slots 28 which is not covered by the injection points 34, the molding module is additionally enclosed by in this case two sealing plates 42.

(27) A line core 6 is fed in continuous fashion to the tool mold 24, with the plastics compound 30 being applied to the line core. Both the line core 6 and the molding elements are in this case moved in the conveying direction 36 and relative to the injection points 34. Here, the molding elements 26 are repeatedly divided into the respective halves 26A, 26B and, by a mechanism not illustrated in any more detail here, conveyed back in order to be assembled again and guided past the injection points 34 again.

(28) During the production process, the line core 6 is fed to the tool mold 24, and is removed from the tool mold 24, that is to say conveyed out of the tool mold, with the applied outer shell 8, by two guide elements 44A, 44B which in this case are in the form of conveying elements. Here, the line core 6 is also held under tension by the guide elements 44A, 44B in order to prevent slippage of the line core 6 relative to a predefined longitudinal axis L during the injection of the compound 30 and in order to compensate a possible expansion of the line core 6, again in order to avoid slippage. To realize a tensile load, it is the case in the embodiment shown here that one guide element 44A is in the form of a braking crawler and the other guide element 44B is in the form of a thrust crawler.

(29) FIG. 5 schematically illustrates a second exemplary embodiment for the production of a line 2. By contrast to the process described above, the line 6 is held on the tool mold 24 by two guide elements 44A, 44B in the form of holding jaws, and the line 6 is guided together with the tool mold 24 past the injection points 34. In particular, the line 2 is in this case manufactured in its entirety. After the injection of the compound 30 and the hardening thereof, the line 2 is removed from the tool mold 24, and the tool mold is returned and a new section of the line core 6 is fed in. The process is quasi-continuous, by contrast to the purely continuous process described in FIG. 4.

(30) FIG. 6 illustrates an alternative refinement of the molding process, which has a continuous process part and an injection-molding-like process part, specifically an extrusion step and an end step. For this purpose, the arrangement shown in FIG. 6 comprises first a tool mold 24 which has a molding module 26 which, in the extrusion step, serves as a mouth piece and which, in the end step, serves as a mold for an in particular end-side subsection 14 of the line 2.

(31) For the production of the line 2, a line core 6 and a plastics compound 30 are fed to the molding module 26 via an extrusion mandrel 46. Here, the line core 6 is fed to the molding element 26 in centered fashion, that is to say on a longitudinal axis L, which in the exemplary embodiment shown here is simultaneously a central axis of the finished line 2, via a projection 48 of the extrusion mandrel 46.

(32) The plastics compound 30 is fed to the molding module 26 over the outer wall of the extrusion mandrel 46, which in the embodiment shown here is inserted into a material distributor 50 and, together with the latter, forms a conical-shell-shaped, generally annular hollow space 52. Via the hollow space 52, the compound 30, which is introduced into the material distributor 50 by an injection unit 32 (not illustrated here), is applied to the line core 6 in particularly uniform fashion in a radial direction with respect to the longitudinal axis L. Here, the molding module 26 is in particular suitably temperature-controlled in order to keep the plastics compound 30 in a flowable state.

(33) The line core 6 and the compound 30 are then conveyed through the molding module 26 in the conveying direction 36 into a cooling module 54. The cooling module is thermally insulated with respect to the molding module 26 by an insulator 56 and furthermore has a number of coolant bores 58 through which a cooling liquid is pumped. In the cooling module 54, the compound 30 is cooled and hardened, such that, at the end of the cooling module, the line core 6 is equipped with a finished outer shell 8 for forming a shell section 10.

(34) It is also shown in FIG. 6 that the line 2 may also be molded onto an already manufactured semifinished part 60. The semifinished part 60 illustrated here contains a bifurcation for splitting into two separate partial strands, as is common for example in the case of earphones. The semifinished part 60 is then, at the start of the process, suitably placed into the tool mold 24 such that the line 2 can thereafter be molded on directly and in any desired length.

(35) To complete the line 2, in the end step of the process shown in FIG. 6, the conveyance of the line core 6 is stopped, and the compound 30 that remains in the molding module 26 is hardened. For this purpose, the molding module 26 is in particular cooled. Through corresponding design of the molding cavity 38 of the molding module 26, that partial section 14 which is now arranged at the end side on the line 2 can be designed in virtually any desired manner. In the exemplary embodiment shown here, the outer shell 8 is, on the subsection 14, formed so as to widen counter to the conveying direction 36.

(36) FIG. 7 shows the tool mold 24 from FIG. 6 in an exploded illustration of a sectional view. It is possible to clearly see the extrusion mandrel 46, the material distributor 50, the molding module 26, the insulator 56 and the cooling module 54. The molding module 26 and the cooling module 54 are in this case in particular divisible in order to facilitate a removal of the line 2 after the end step.

(37) FIG. 8 schematically shows a third exemplary embodiment of a line 2, which can be manufactured in a simple manner in particular by means of a molding process described in conjunction with FIGS. 4 and 5. The line 2 is configured as an endless line, that is to say can be manufactured in a predefined length which is adjustable in accordance with the usage requirements during the production process. The line 2 contains a line core 6 which in this case is configured as a band to which a flat-band-like outer shell 8 has been applied. Along the line 2, a number of subsections 14 formed as fastening points 62 are arranged in repeating fashion at predefined intervals A, which subsections are in this case formed as fir-tree-like studs. The fastening points 62 have in this case been manufactured during the formation of the outer shell 8, that is to say are formed in one piece with said outer shell. Then, between two fastening points 62, there extends in each case one shell section 10 which has a cross-sectional geometry which does not vary along the longitudinal axis L.

(38) The line 2 illustrated in FIG. 8 can however also be produced by means of the process described in FIG. 6. For this purpose, the molding module 26 has a mold cavity 36 which is suitable for forming a fastening point 62. Then, in the extrusion step, a shell section 10 is firstly manufactured, to which a fastening point 62 as subsection 14 is then attached in a subsequent end step. After the hardening, the molding module 26 is opened, the line 2 is removed, and the line is used as a semi finished part 60 for the integral molding of a further shell section 10 with a terminating fastening point 62. Here, there is advantageously no need for the line core 6 to be severed. As a result, it is possible to produce a line 2 of any desired length with multiple fastening points 62 at predefined intervals A, with in each case one shell section 10 arranged between the fastening points 62.

(39) The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: 2 Electrical line 4 Line longitudinal direction 6 Line core 8 Outer shell 10 Shell section 12 Conductor wires 14 Subsection 16 Sealing bush 18 Plug housing 20 In-ear earphone 22 Plug element 24 Modular tool mold 26 Molding module 26A, 26B Half 27A Feed opening 27B Exit opening 28 Gate slot 30 Plastics compound 32 Injection unit 34 Injection point 36 Conveying direction 38 Molding cavity 40 Ribs 41 Module cage 42 Sealing plate 43 Alignment element 44A, 44B Guide element 45 Closure plate 46 Extrusion mandrel 48 Projection (of the extrusion mandrel) 50 Material distributor 52 Hollow chamber 54 Cooling module 56 Insulator 58 Coolant bores 60 Semifinished part 62 Fastening points L Longitudinal axis A Interval