Method for manufacturing a cable set

Abstract

Method for manufacturing a cable assembly (2) in which several conductors (6) are held together as a conductor bundle (4) and a common sheath (8) is formed around these conductors (6), wherein the conductors (6) are placed in a molding chamber (16) and the conductors (6) are potted by injecting a curable sheath material (M) into the molding chamber (16), which is subsequently cured by subjecting the conductors (6) and the sheath material (M) to microwave radiation (S), wherein the sheath material (M) is cured by heating the conductors (6) by means of the microwave radiation (S), wherein the sheath material (M) is microwave-inactive or is sectionally microwave-active and microwave-inactive.

Description

[0001] The invention relates to a method for producing a cable set with several lines which are combined to form a line bundle and around which a common sheath is formed which is made of a curable sheath material.

[0002] A corresponding cable set is known, for example, from WO 2012 / 119 618 A1.

[0003] A cable harness is generally understood to be a pre-assembled bundle of cables in which a plurality of individual cables are connected to one another according to a predefined route or layout and over a defined length. Cable harnesses usually have a branched structure with numerous branches, ramifications, or branches. The individual cables each have a limited length; the cable harness as a whole is therefore a prefabricated, pre-assembled piece product that is usually adapted to a specific installation situation. Contact elements such as plugs or the like are often already attached to the individual ends of the individual cables. Such cable harnesses are also installed in particular in the automotive industry as part of a vehicle's on-board network and are used, for example, to electrically connect a plurality of consumers to a central distribution or control unit.

[0004] The production of such a cable harness is still largely carried out manually today. First, the individual wires required for the cable harness—i.e., the initially separate wires—are laid on a so-called assembly or cable board according to the defined and desired routing. The wires are held in place by holders. The loose bundle of wires thus formed from the individual wires is then secured by applying banding around the individual wires. This is done manually and, for example, with special self-adhesive tapes.

[0005] There are various options for banding, including full banding, where the cable bundle is completely covered with banding, and economy banding, where the cable bundle is only partially covered with banding. The banding therefore has different functions depending on where the cable harness is used. Its primary function is to connect the individual cables. Banding is also often used to attach mounting elements or additional functional elements. Furthermore, the banding serves as mechanical protection, for example, as anti-rattle protection.

[0006] If necessary, the cable bundle is surrounded by a foamed body, at least in part, to create, for example, a so-called dimensionally stable cable harness in which the branches and ramifications are fixed in their geometry. For such foamed cable harnesses, the cable bundle is usually inserted into a mold, a so-called foam mold, into which a foamable material, such as a polyurethane material, is then introduced.

[0007] Since these cable harnesses are not sold by the meter, i.e., not continuous, and are characterized by numerous branches and ramifications, the application of such banding has not yet been automated. A cable harness typically consists of only very short, branch-free, straight sections, the length of which is usually only a few tens of centimeters.

[0008] US 2014 / 0 295 057 A1 describes a continuous process for applying a piezoelectric coating using irradiation (IR, UV).

[0009] DE 18 09 807 A describes a vulcanization process in which the material is heated using microwaves. For this purpose, metal particles are incorporated into the material.

[0010] DE 20 2011 105 269 U1 describes an electrical installation cable with aluminum wires.

[0011] DE 199 63 491 A1 describes a process for producing insulation for electrical conductors by spray sintering.

[0012] DE 22 08 545 B2 describes a method for spraying insulating discs onto the inner conductors of high-frequency coaxial cables.

[0013] DE 10 2009 001 751 A1 describes a method for producing a cable harness in which a cable is encapsulated with a curable material.

[0014] DE 199 63 332 A1 discloses a wire conductor carrier in which several current conductors are embedded in an insulating carrier, with sections of the current conductors being exposed through windows in the insulating carrier.

[0015] Against this background, the object of the invention is to provide an improved method for producing a cable harness, which should be as simple and, in particular, as automatic as possible.

[0016] The object is achieved according to the invention by a method having the features according to claim 1. Advantageous embodiments, further developments and variants are the subject of the subclaims.

[0017] The cable set has a plurality of lines which are combined to form a line bundle and around which a common sheath is formed which is made of a curable sheath material, wherein the sheath material is cured by exposing the lines and the sheath material to microwave radiation.

[0018] To manufacture the cable harness, several wires are held together as a bundle, specifically to define the specific routing of the individual wires. A common jacket is then formed around these wires by applying a curable jacket material to the wires, which is then cured by exposing the wires and the jacket material to microwave radiation.

[0019] The use of microwave radiation offers the particular advantages in terms of manufacturing technology that it penetrates the irradiated material particularly well and thus also advantageously undercut geometries can be realized. Furthermore, in particular, manufacturing tolerances in the dimensions of the cables and the cable harness as a whole have only an insignificant influence on the curing.

[0020] A further advantage of curing using microwave radiation is that it can completely penetrate the cable harness and any holding device used to hold it, thus ensuring complete and particularly uniform curing of the jacket material. The manufacturing process is therefore particularly reliable and therefore also suitable for automated processing, which means that the cable harness can be manufactured more efficiently and cost-effectively. Microwave radiation is significantly easier and safer to handle than, for example, X-rays. Furthermore, the use of microwave radiation compared to curing using light, e.g., UV radiation, offers significantly greater flexibility in designing the cable harness, particularly with regard to the choice of material.

[0021] Another significant advantage arises from the fact that the cables each have a typically metallic conductor, which absorbs microwave radiation well and heats up upon exposure. Therefore, the sheath material is cured by heating the cables with microwave radiation. By heating the bundle of cables via the conductors and indirectly heating the sheath material, the absorption properties of the sheath material with regard to microwave radiation are no longer important, which means that a particularly large number of materials are available.

[0022] Microwave radiation is generally understood to mean electromagnetic radiation with a frequency in the range of approximately 1 to 300 GHz. The microwave radiation is at least partially absorbed by the radiated device, which then leads to a corresponding heating of the cable harness and a hardening of the sheath material. Since the cable harness is usually made of different materials, it is advisable to vary the frequency of the microwave radiation over time in order to achieve the most homogeneous absorption and heating possible.

[0023] In a first variant, microwaves are applied in a microwave oven, into which the cable bundle with the sheathing material applied to it is inserted. The cable harness is then exposed to microwave radiation as a whole. In a second variant, location-selective exposure to microwave radiation is achieved in particular by providing the radiation in a location-selective manner using an antenna, in which the antenna only radiates into a predetermined and limited spatial area. Instead of a microwave oven surrounding the cable harness, an antenna is used, which can preferably be brought closer to the component at will, for example in the form of a tool attached to a robot arm. In this embodiment, any installation space limitations are then advantageously eliminated, so that cable harnesses of any size and shape can be manufactured.Preferably, the microwave radiation is therefore provided by a corresponding antenna that is moved along the sheath material to be cured. This variant is particularly suitable for continuous processing or in assembly line production of serial products.

[0024] The cable bundle preferably has at least one branch, and the sheath is formed in the region of the branch, i.e., is formed with corresponding branches. This results in a particularly flexible design of the cable harness. The sheath covers the branch. Such sheathing of a branch or branch of the cable bundle is already complex with manual banding and, in particular, is not economically feasible with an automated process. However, by simply applying the sheath material and subsequent curing, even branches can be easily sheathed.

[0025] In one variant, however, the cable set has no branching.

[0026] The sheath material is preferably applied by potting the wire bundle, i.e. at least a section thereof, with the sheath material, which has a suitable viscosity. As a result, in a preferred embodiment of the cable harness, the wires are solidly potted and the sheath material is also arranged between the wires. This results in a particularly robust and stable cable harness. This also has a particularly high level of rigidity. This is achieved during production in particular by the sheath material partially or completely penetrating and filling the spaces formed by the individual wires during potting of the wire bundle. In this way, particularly good protection against moisture penetration is then formed for the entire wire bundle. At the same time, the individual wires are held in a defined position relative to one another.

[0027] Additionally or alternatively, in a suitable embodiment, the sheath material is applied to the cable bundle as a mesh structure, as a spray coating, or in a coiled form. This saves material in the sheathing process, particularly in cases where complete sheathing of the cable bundle is not desired. A coiled or mesh structure or a sufficiently thin spray coating also ensures high cable flexibility. Suitable methods for applying the sheath material include beading, brushing, dipping, wiping, and spraying.

[0028] In one variant, flexible sections of a cable harness are formed by means of a mesh or spiral structure or by spray application, and correspondingly rigid sections are formed elsewhere by solid potting or thick spray application.

[0029] In particular, to hold and group the individual cables together before the sheath material is applied, a number of fixing devices, in particular banding, are attached to the cable bundle in sections. This makes it easy to specify and fix the desired route of the cables. In addition, the fixing devices also act as seals, particularly during potting, preventing the sheath material from accidentally penetrating areas not to be potted. Alternatively or additionally, the fixing devices also seal the cable bundle in sections against the penetration of sheath material, thus enabling the formation of flexible sections of the cable harness, namely where the fixing device is attached. In a practical variant, the fixing device has additional functional elements, for example holding elements to simplify the installation of the cable harness. In this case, the fixing device generally remains on the cable harness initially.Alternatively, the fixation is removed after the sheath material has cured, in particular to expose the section thus concealed and make it accessible for further processing or assembly, for example. The fixation then acts in particular like a mask, preventing sheathing from being applied to the masked section.

[0030] In a suitable refinement, two fixings are attached to the cable bundle, between which the sheath extends along the cable bundle. The fixings are then arranged at the ends of the sheath. Attaching two fixings to define the sheath is particularly advantageous during potting, as the fixings create a seal and prevent sheath material from escaping.

[0031] According to the invention, the sheath material is microwave-inactive, i.e., microwave-transparent, and absorbs microwave radiation only slightly or not at all. Curing occurs essentially indirectly via heating the cables. In this embodiment, it is possible, for example, to select the same or a similar material as that used for the cable sheaths as the sheath material in order to achieve a particularly good bond between the cables and sheath during heating and curing, thereby making the cable harness particularly rigid and robust. Suitable microwave-transparent materials include, for example, PP (i.e., polypropylene) and PVC (i.e., polyvinyl chloride).

[0032] In principle, a variant is also suitable in which the material is both microwave-active and microwave-inactive, i.e., it is only microwave-active and microwave-inactive in certain sections. This results in different sections being formed along the cable harness, each of which then offers the advantages mentioned above. The jacket is then made of different jacket materials at different points along the cable harness, for example. In one variant, a fundamentally microwave-inactive material is used, and then an additive is mixed into it, at least locally, in order to make certain sections of the applied jacket material microwave-active.

[0033] A microwave-active material is understood in particular to be a material that absorbs microwave radiation particularly well and can therefore be heated particularly efficiently. Particularly suitable microwave-active materials include EP, i.e. epoxy resin, PU, ​​i.e. polyurethane, or materials to which a microwave-active additive has been added. A microwave-active jacket material is then heated directly during curing by absorbing microwave radiation. In this embodiment, the heating and curing of the jacket material takes place in two ways: firstly, directly by absorption of microwave radiation by the jacket material and secondly, indirectly by absorption of microwave radiation by the conductors of the lines. Overall, curing is therefore particularly efficient and rapid.

[0034] In a suitable embodiment, the sheath material is opaque to electromagnetic radiation with a wavelength in the range from 100 to 1000 nm, i.e. generally to light and in particular to visible light and UV radiation. This enables a design in which the interior of the cable harness, in particular the individual lines, are not visible from the outside. When curing using UV radiation, such a variant is usually not possible because correspondingly opaque materials cannot be completely cured, but only superficially. However, the use of microwave radiation and in particular the indirect heating of the sheath material via the lines enables the use of appropriately colored, particularly dark-colored materials to form the sheath and thus increases the design flexibility of the cable harness.

[0035] The sheath preferably has a thickness of at least 1 mm, making the cable harness particularly robust. Such thicknesses cannot be produced using conventional methods, especially UV irradiation, because the UV radiation cannot penetrate sufficiently into the sheath material. However, any thickness is possible in principle using microwave radiation. Thickness is then understood in particular to mean that the cured sheath material has an outer, typically annular, outer region in which no cables are arranged.

[0036] In a suitable variant, the sheath is foamed, making it particularly lightweight and thicker than a non-foamed material. Foaming of the sheath is preferably carried out before curing, for example, before or during application of the sheath material to the cable bundle. For this purpose, the sheath material is foamed either chemically, for example, by adding a foaming agent, or physically, for example, by applying a gas.

[0037] In principle, it is possible to combine almost any cable into a cable bundle. In a suitable design, the cables each have a conductor cross-section in the range of 0.35 to 2.5 mm 2In one variant, cables with different conductor cross-sections are used. Alternatively or additionally, cables with smaller or larger conductor cross-sections are also used. In one variant, a number of cables are designed as fiber optic cables. In general, the cables in the cable bundle are used primarily for power and / or signal transmission.

[0038] The cables each have a sheath, preferably made of PVC or PP. These materials are particularly resistant to heat and thus particularly well-suited for the manufacturing process. However, in principle, all conventional cable sheath materials can also be used.

[0039] The cable set, for example, comprises approximately 2 to 200 wires. Alternatively or additionally, the cable set includes twisted wires.

[0040] The cable harness's jacket is preferably made of PU or EP. These materials are particularly well-suited for potting and subsequent curing, making them ideal for the overall manufacturing process.

[0041] After the end of the irradiation, in one variant a cooling phase follows, in which the cable set remains in the mold chamber for a certain cooling time without being irradiated.

[0042] After curing, the jacket material is preferably post-cured during a rest period. For this purpose, the cable harness is first removed from the mold chamber. For post-curing, the irradiated cable harness is initially left to rest for a period of time, preferably several hours, for example, 24 hours, before further processing or handling. The duration of the rest period generally depends on the materials used and may be shorter or even significantly shorter.

[0043] To simplify potting, the cables are placed in a mold chamber for holding and then potted by injecting the sheath material into the mold chamber. The mold chamber, i.e. casting mold, is designed in particular like an injection molding tool into which the cables, i.e. the cable bundle, are initially placed completely or only in sections. For this purpose, suitable holders or receptacles are designed in particular in the mold chamber. In an advantageous development, as described above, a number of fixings are additionally attached to the cable bundle, which are then expediently seated in the holders and form a corresponding seal there in order to prevent the injected sheath material from escaping from the mold chamber.For injecting the shell material, the mold chamber then has a number of suitable injection openings through which the shell material preferably enters the mold chamber automatically.

[0044] The molding chamber is preferably made of a microwave-inactive material in order to introduce as much microwave radiation energy as possible into the cable bundle. Alternatively, however, a microwave-active design of the molding chamber, at least in some areas, is also conceivable, thereby achieving additional indirect and correspondingly localized heating of the jacket material.

[0045] The mold chamber forms a cavity, by means of which, in an advantageous further development, an outer contour of the cable harness is predetermined. By appropriately designing the cavity, i.e., an inner contour of the mold chamber, the outer contour of the cable harness is then predetermined. This allows a variety of additional functions to be implemented for the sheath. The sheath then has a corresponding external structure, for example, to improve the slip resistance of the cable harness. Additionally or alternatively, holding or fixing elements for installing the cable harness are formed as parts of the sheath, i.e., holding or fixing elements are then integrally formed on the sheath.

[0046] The mold chamber advantageously comprises several reversibly connectable mold chamber sections. The lines are held by inserting them into one of the mold chamber sections, and the mold chamber is then closed by the remaining mold chamber sections. This closed design of the mold chamber then enables a particularly complete formation of the shell.

[0047] During curing of the sheath material, its temperature is preferably measured, and the microwave radiation is automatically controlled or regulated depending on the temperature, in particular to achieve a suitable heating level. This prevents excessive heating and potential damage to the cable harness, while also preventing insufficient heating and thus potentially incomplete curing.

[0048] To obtain particularly reliable information about the temperature of the shell material, the temperature is preferably measured at a sprue of the shell material. A particularly suitable method is to measure the temperature through an injection opening in the mold chamber, where the sprue of the shell material is directly accessible from outside the mold chamber. The measurement can be performed, for example, using a contact thermometer or optically using an infrared thermometer.

[0049] Particularly good results are achieved during production in particular by the temperature in a preferred embodiment being in a range from 50 to 200°C, particularly preferably in the range from 70 to 130°C.

[0050] The use of microwave radiation also enables significantly reduced production times compared to conventional manufacturing. In a preferred embodiment, the cables and the sheathing material are exposed to microwave radiation for approximately 5 to 300 seconds to cure them. Tests have shown that this time interval ensures sufficient curing of the sheathing material. Irradiation over a period of approximately 50 to 100 seconds is particularly preferred. In the case of a foamed sheath, the sheathing material is preferably exposed to microwaves for approximately 180 to 240 seconds.

[0051] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In each case, the following schematically show: Fig. 1 a cable set, Fig. 2 the cable set in cross-section, and Fig. 3a to 3c each show a step of a method for producing the cable harness.

[0052] In the Fig. 1 and Fig. 2 schematically shows an embodiment of a cable set 2, wherein Fig. 1 shows this in a plan view and Fig. 2 a cross-section of the cable set 2 along the Fig. 1. The cable set 2 is in Fig. 1 is only shown in sections, but has a finite length overall and is provided with plugs or other contact elements at the ends not shown here.

[0053] The cable set 2 has a cable bundle 4 consisting of several cables 6. These are each designed as wires, with a conductor (not shown in detail) that is surrounded by a cable sheath. The cable bundle 4 is also surrounded by a sheath 8 made of a curable sheath material M. Fig. 1 shows that the cable harness 2 has a branch 10, at which the initially jointly routed lines 6 are split into two sub-strands. In a variant not shown, the cable harness 2 does not have a branch 10. The sheath 8 is also branched accordingly at the branch 10. Fig. 2 also clearly shows that the sheath material M completely surrounds all of the wires 6 and is also present in the spaces between the various wires 6, thus solidly encapsulating the wires 6. These wires 6 are arranged in an inner region of the cable harness 2, so that the sheath 8 has a certain thickness D on the outside, within which no wires 6 are arranged. This thickness D is preferably approximately one millimeter or more.

[0054] In a variant not shown, the sheath 8 is not fully cast and therefore does not penetrate all the spaces between the wires. Additionally or alternatively, the sheath 8 is also not formed over the entire circumference, but only on partial areas of the wire bundle 4, for example, in the form of a mesh or helical structure. The sheath material M is applied, for example, by beading, brushing, dipping, scraping, spraying, etc.

[0055] Cable set 2 shows, as particularly Fig. 1, a number of fixings 12, which in the embodiment shown here are designed as bands and simultaneously serve to delimit the sheath 8. In other words: the sheath 8 is formed only in sections along the cable bundle 4, specifically between the fixings 12. Furthermore, the fixings 12 serve to hold the cables 6 together during the production of the cable set 2.

[0056] In the Fig. 3a to 3c each show a step of an exemplary method for producing the cable harness 2. In the Fig. 3a, the cable bundle 6 is provided with the fixings 12 and inserted into a mold chamber part 14 of a mold chamber 16 for holding purposes. Since no sheath 8 is to be formed at the end of the cable harness 2, the corresponding ends are arranged outside the mold chamber 16 and the fixings 12 form a boundary of a cavity K formed by the mold chamber 16, i.e., an interior of the mold chamber 16. During insertion, in particular the branch 10 is also predetermined and formed by appropriately arranging the various cables 6.

[0057] In a second in Fig. In the process step shown in Figure 3b, the mold chamber 16 is then closed with a further mold chamber part 14. The mold chamber 16 thus comprises two mold chamber parts 14, which are placed on top of one another and, for example, screwed together. A number of injection openings 18, here three, are now introduced into one of the mold chamber parts 14, through which the shell material M is subsequently injected into the mold chamber 16. In particular, several sprues of the shell 8 are also formed in these injection openings 18. The shell material M is, for example, epoxy resin or polyurethane. Generally, the shell material M is a curable material which initially has a corresponding viscosity for processing and hardens upon curing and thus becomes solid.

[0058] Curing takes place in Fig.3c, in which the molding chamber 16 and the cable bundle 4 located therein, as well as the sheath material M, are exposed to microwave radiation S. The irradiation takes place from all sides by moving the molding chamber 16 into a microwave oven (not shown in detail). In an alternative (not shown), however, only local irradiation takes place, for example by means of a microwave antenna which is guided along the sheath material M. Depending on the choice of the sheath material M, its curing takes place due to different processes. In each case, microwave radiation S is absorbed by the conductors of the cables 6, so that they heat up and accordingly lead to a curing of the sheath material M. In the event that the sheath material M is a microwave-active material, it also absorbs microwave radiation S itself and is thus also heated directly.The mold chamber 16 is usually microwave-transparent, but in an alternative it is also microwave-active and then contributes accordingly to the curing of the jacket material M.

[0059] During irradiation, the intensity of the microwave beams S is regulated as a function of the temperature of the sheath material M, wherein the temperature is preferably measured at at least one of the sprues in the injection holes 18 of the mold chamber 16. The irradiation is then carried out, for example, in such a way that the sheath material M is kept at a temperature of approximately 80° Celsius for approximately 150 seconds. The irradiation is then stopped. If necessary, a cooling phase with a certain cooling time follows. The cable harness 2 is then demolded, i.e. in particular removed from the mold chamber. If necessary, post-curing then takes place during a rest phase. List of reference symbols 2 cable sets 4 cable bundles 6 Line 8 coat 10 Branching 12 Fixation 14 mold chamber part 16 mold chamber 18 Injection opening D Thickness K Cavity M sheath material S Microwave radiation

Claims

[1] Method for producing a cable harness (2), in which a plurality of lines (6) are held together as a line bundle (4), and a common sheath (8) is formed around these lines (6), wherein for this purpose the lines (6) are placed in a molding chamber (16) and the lines (6) are cast by injecting a curable sheath material (M) into the molding chamber (16), which is then cured by exposing the lines (6) and the sheath material (M) to microwave radiation (S), wherein the sheath material (M) is cured by heating the lines (6) by means of the microwave radiation (S), wherein the sheath material (M) is microwave-inactive or is microwave-active and microwave-inactive in sections. [2] Method according to the preceding claim, characterized by that the sheath material (M) is post-cured in a rest phase after curing. [3] Method according to one of the preceding claims, characterized by that the mold chamber (16) forms a cavity (K) by means of which an outer contour of the cable harness (2) is predetermined. [4] Method according to one of the preceding claims, characterized by that the mold chamber (16) has a plurality of reversibly connectable mold chamber parts (14), wherein the lines (6) are held by being inserted into one of the mold chamber parts (14) and the mold chamber (16) is then closed by means of the remaining mold chamber parts (14). [5] Method according to one of the preceding claims, characterized by that during curing a temperature of the jacket material (M) is measured and the microwave radiation (S) is controlled or regulated automatically and depending on the temperature. [6] Method according to the preceding claim, characterized by that the temperature is measured at a sprue of the jacket material (M). [7] Method according to one of the two preceding claims, characterized by that the temperature is in a range of 50 to 200 °C. [8] Method according to one of the preceding claims, characterized by that the lines (6) and the sheath material (M) are exposed to microwave radiation (S) for approximately 5 to 300 seconds to cure.

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