EP4038648A1

EP4038648A1 - Method for producing coaxial cables having a thin-walled, radially closed outer conductor

Info

Publication number: EP4038648A1
Application number: EP20771308.2A
Authority: EP
Inventors: Ralf Egerer; Olaf Petersen; Steven DINKEL
Original assignee: Nexans SA
Current assignee: Nexans SA
Priority date: 2019-09-30
Filing date: 2020-09-16
Publication date: 2022-08-10
Also published as: WO2021063682A1; EP3799083C0; EP3799083B1; CN114514587A; JP2022550395A; US20240055158A1; EP3799083A1

Abstract

The invention relates to a method for continuously producing coaxial cables (224) having a thin-walled, radially closed outer conductor of non-ferrous metal, which method comprises the feeding of a flat strip of the non-ferrous metal to a forming device (212), the thickness of the strip corresponding to the wall thickness of the coaxial cable. The forming device is designed to continuously form the fed flat strip into a shape corresponding to the outer conductor of the coaxial cable around a cable core fed before the closing of the outer conductor. After the forming, two opposite edges of the flat strip lie flush against each other in a contact region, which edges are welded to each other by a welding device (216) continuously by means of a laser, which emits light of a wavelength of less than 600 nm. The laser heats a point in a welding region that has a diameter that is less than 20% of the cross-sectional dimension of the coaxial cable. The welded coaxial cable is pulled from the welding region and, after the introduction of a parallel corrugation or helical corrugation, is received in a receiving apparatus (226).

Description

Process for the production of coaxial cables with a thin-walled, radially closed outer conductor

FIELD The invention relates to the production of coaxial cables with an outer conductor made of non-ferrous metals, in particular the continuous production of such cables with thin-walled outer conductors.

background

Thin-walled, radially closed hollow profiles, in particular with a circular cross section, can be used as the outer conductor of HF cables or coaxial cables. An inner conductor encased by a dielectric is then arranged in the center of such a hollow profile. The dielectric can, for example, comprise a plastic with a suitable relative dielectric constant, but it is also possible to separate the inner conductor from the outer conductor essentially only by means of air or another electrically non-conductive gas. For this purpose, the inner electrical conductor can be held in the center of the hollow profile by means of spacers arranged at intervals, or a large-pored foamed plastic can be used which predominantly contains air or the gas. In order to achieve better flexibility of the coaxial cable, which is necessary for laying in different directions with the smallest possible bending radii, and at the same time to obtain a dimensionally stable outer conductor, the outer conductor of the coaxial cable is provided with a helical or parallel corrugation, as in Figure 4 shown as an example. The corrugation process requires a wall thickness that is as uniform as possible for the hollow profile forming the outer conductor; at the same time, a wall thickness that is as thin as possible is desirable for reasons of material and cost savings. In addition, it is desirable that the outer conductor is manufactured in a continuous process in order to be able to manufacture larger continuous lengths of coaxial cables. In a continuous process for the production of coaxial cables, a cable core consisting of an inner conductor and a dielectric is fed to a tube forming process. In the tube-forming process, a flat strip made of a non-ferrous metal, e.g. copper, is formed into a tube that is slotted in the longitudinal direction and encases the cable core. The flat strip, which is shaped into a tube, is welded longitudinally along the slot and then corrugated.

The welding is carried out using an arc process such as tungsten inert gas welding (TIG). However, this means that wall thicknesses less than 0.15 mm cannot be welded in a process-reliable manner. The pipes welded with the known arc process also show a pronounced weld bead which protrudes into the inside of the pipe and which has a negative impact on the electromagnetic properties of the coaxial cable. Furthermore, pipes with a welding diameter of less than 0 4.0 mm cannot be produced using the known method. As a result, the dimensioning of the corrugated tube forming the outer conductor is limited towards the bottom and thus also the minimum diameter of the coaxial cable. This in turn leads to a larger minimum bending radius of the coaxial cable.

For certain applications, hollow profiles made of non-ferrous metals (non-ferrous metals) are particularly suitable, for example copper or aluminum. Copper pipes in particular can also be used as electrical shields or outer conductors in coaxial cables or for waveguides. Thin-walled hollow profiles with comparatively small diameters and small wall thicknesses are required in coaxial cables, among other things in order to keep the use of materials and weight low. In particular, wall thicknesses of less than 0.15 mm, regardless of the diameter of the pipe, can no longer be produced reliably and with the required quality of the weld seam by means of arc welding. Hollow profiles made of non-ferrous metals with wall thicknesses and diameters smaller than those mentioned must therefore be brought to the desired final dimensions by processing steps that follow the actual pipe production. As in the continuous production of long coaxial cables, the inner The conductor and the insulation have to be introduced into the flat strip made of non-ferrous metal, which is formed into a slotted hollow profile, before welding, no drawing processes can be used to reduce the wall thickness after welding. The hollow profile must therefore already be made from material with the desired wall thickness.

In principle, it is advantageous if coaxial conductors are manufactured in a largely continuous manufacturing process that has to be interrupted as rarely as possible in order to obtain sections that are as long as possible. If necessary, parts of a required length can then be cut from the long coaxial conductors, with only a small remainder of the cut remaining, if at all. In general, of course, any saving in process steps in production is advantageous.

It is therefore an object of the invention to provide a method and a device which reduce the amount of material required for the continuous production of large lengths of coaxial cables and enable a reduced weight of the cable.

Summary of the invention

This object is achieved by the method specified in claim 1 and the device specified in claim 8. Further developments and refinements are given in the dependent claims.

In the method according to the invention for the continuous production of thin-walled coaxial cables, in particular also small cross-sections, a flat strip of a non-ferrous metal is first fed, the thickness of which corresponds to the wall thickness of the outer conductor of the coaxial cable to be produced. The width of the supplied metal strip preferably already corresponds to the circumference of the outer conductor of the coaxial cable. If the supplied metal tape is wider than required by the circumference of the outer conductor of the coaxial cable, or if the edges of the metal tape are not sufficiently smooth, the metal tape can be cut to size on one or two sides in a continuous process during the feeding. In the present description the term refers to "Small cross-section coaxial cables" refer to coaxial cables with cross-sections of a few millimeters. The expression “thin-walled” relates to wall thicknesses of a few tenths of a millimeter, in particular less than 0.15 mm. In this description, the term non-ferrous metal is used both for the metals themselves and for their alloys.

The metal strip, which is present in the appropriate width, is shaped in a single or multi-stage continuous forming process into a hollow profile which has the desired cross section and which forms the outer conductor of the coaxial cable. The forming process can include bending in several stages in succession in the longitudinal direction of the strip, for example on appropriately set up rollers and profiles. The cross-section can be round, oval or also arbitrarily polygonal. Before or during the forming process, before the hollow profile is closed, the cable core, which comprises an inner conductor sheathed with a dielectric, is fed. The cable core can comprise further layers.

The hollow profile, which has received the cable core, has after reshaping an area which runs in the longitudinal direction of the hollow profile and in which the edges of the metal strip are flush with one another. The flush edges of the hollow profile are now welded to one another along the abutting edge and thus closed radially. According to the invention, the welding is carried out with a laser which emits light with a wavelength of less than 600 nm, preferably in a range between 550 and 450 nm. Wavelengths in a range below 450 nm can also be used advantageously according to the invention. The laser brings light energy into a point in the weld area, which is absorbed when it hits the surface of the weld metal and converted into heat. Light in the wavelength ranges mentioned according to the invention is absorbed much better by many non-ferrous metals even at room temperature than, for example, light in the infrared spectrum with wavelengths above about 800 nm. In fact, light is already absorbed by many non-ferrous metals at wavelengths above about 600 nm -Metals are only so badly absorbed, so lasers with particularly high output powers and special cooling measures would be required to weld the non-ferrous metal. In addition, the absorption at wavelengths greater than 600 nm is strongly dependent on the nature of the surface, while the influence of the surface quality is greatly reduced at the wavelengths used according to the invention. In addition, because of the strong temperature dependence of the absorption, especially at larger wavelengths, rapid regulation of the energy introduced into the active welding area is also required, which is almost impossible to implement, so that the quality of the weld seam can fluctuate greatly. The inventive use of light with wavelengths less than 600 nm creates a more stable weld pool and leads to an overall more stable process that delivers longitudinally welded hollow profiles of high quality and produces fewer rejects with a high degree of energy efficiency of the welding process. In addition, if the wavelength used according to the invention is less than 600 nm, there is no need to prepare the welding area, which causes a reduction in the reflection and thus an increase in the absorption of the laser light. Of the

The welding area does not have to be roughened or preheated, for example, and there is also no need to apply a layer of a substance in the welding area which, as a "mediator", converts the radiated light energy into heat and transfers it to the weld metal, so that its temperature-dependent degree of absorption in for the wavelength used reaches more favorable ranges. This eliminates the risk of parts of the substance used as a mediator getting into the weld seam.

The absorbed light causes the metal to heat up strongly. In order to bring a sufficiently high energy into the material to be welded, the light must be strongly focused. A strong focus is also necessary because the welding should only take place in the contact area of the edges along the slot. Due to the heat conduction within the non-ferrous metal, areas directly adjacent to the point of impact of the laser beam can also heat up and, if necessary, melt. Particularly with small cross-sectional dimensions of the hollow profiles to be produced, for example with diameters smaller than 4 mm, the focusing of the laser beam is therefore of great importance in order to achieve the to avoid uncontrolled drainage of liquefied material or a break in the material. In the method according to the invention, the laser beam on the workpiece has a diameter of not more than 20% of the cross-sectional dimensions of the hollow profile, preferably less than 10%. Tests have shown that the diameter of the laser beam down to 5% of the cross-sectional dimensions can still enable weld seams of good quality, in which case further measures may be necessary, for example moving the focal point over the weld area. In the case of a hollow profile with a diameter of 4 mm, the diameter of the laser beam can accordingly be, for example, 400 μm, preferably 200 μm or less. The term cross-sectional dimensions used in this description can refer to a diameter of a hollow profile, or to edge lengths. Depending on the context, the term can also refer to bending radii of edges or the like. The high local energy density at the point of impact of the laser beam on the workpiece causes the material to melt locally on both sides of the abutting edge, so that the melts flow into one another. The material solidifies again when it is no longer hit by the laser beam and forms the weld seam. Since the hollow profile, in which the cable core is accommodated, is continuously guided past the stationary laser, a continuous weld seam is created that connects the two edges. In order to prevent uncontrolled drainage of the liquid material, which has a small wall thickness, the laser power and the speed at which the pipe is guided past the laser must be coordinated with one another. With suitable coordination, smooth weld seams result on the outside as well as on the inside, which do not require any post-processing.

In contrast to the well-known arc welding according to the tungsten inert gas process (TIG) or metal inert gas process (MIG), which prevent the melt from reacting with the ambient air through the inert gas atmosphere and thus enable high seam quality, with the invention used laser welding because of the better The energy input can be controlled even without protective gases. Non-ferrous metals with material thicknesses less than 0.15 mm are butt-welded to one another in such a way that no welding bead is formed on the inside of the pipe, which is no longer freely accessible due to the cable core. In the case of embodiments of the method, the welding point can nevertheless be flowed around or covered with an inert protective gas, for example argon. The use of a protective gas atmosphere can depend, among other things, on the material to be welded and its thickness.

The energy input by the laser can be controlled either by focusing on a larger target area so that the available energy acts on a larger or smaller area as required, or by moving a particularly narrowly focused laser beam to and fro. The focus on a larger target area can also be formed by a laser profile which has a central focal point of high intensity and an annular region of lower intensity surrounding the central focal point. As a result, the weld area can be heated or cooled in a targeted manner along a temperature profile, which can result in a cleaner weld seam and the solidification structure can be influenced in a targeted manner. In addition, laser beams can be pulsed in a simple manner, with the energy input being controlled, for example, via the pulse duration and the pulse spacing.

Laser welding, also known as thermal conduction welding, creates a smooth, rounded weld seam that no longer needs to be reworked. During thermal conduction welding, the energy is distributed outside the area in which the laser strikes, only through thermal conduction into the workpiece. This is why the seam depth - depending on the laser power and the thermal conductivity of the material - is only a few tenths of a millimeter to around 1 millimeter. The thermal conductivity of the material limits the maximum seam depth. As a rule, the seam width is larger than the seam depth. If the heat cannot dissipate quickly enough, the processing temperature rises above the evaporation temperature, so that Metal vapor is generated and the welding depth increases by leaps and bounds. The process then goes into deep welding.

The high quality of the weld seam on the outside and above all on the inside of the pipe produced according to the invention, which has no pronounced material bead along the weld seam, allows coaxial cables with thin wall thicknesses and small diameters to be produced in a continuous process due to the finely controllable energy input into the weld to manufacture.

In one or more refinements of the method, the width of the supplied strip is measured and a cutting width is tracked as a function of the measurement result and a preset value. The width corresponds approximately to the circumference of the hollow profile, which forms the outer conductor of the coaxial cable, along the neutral fiber. The default value can be varied and a shaping device can be controlled accordingly as a function of the varying width of the strip, for example in order to adapt the amount of material required for a clean weld seam.

In the case of embodiments of the method, a temperature profile is measured transversely to the weld seam. The measured temperature profile can be used to control the energy introduced into the welding point. The measured temperature profile can be compared with a default profile, for example, and the control of the energy introduced can include a variation of the focus diameter, a trajectory described by the focus point on the weld metal and / or a change in the pulse duration and / or the pulse spacing of the laser beam. It is also conceivable to regulate the feed speed as a function of the measured temperature profile. The measured temperature profile can also be saved for quality management and documentation purposes.

In the case of embodiments of the method, the weld seam is checked with ultrasound, X-rays, an eddy current measurement or other non-destructive measuring methods. The results of the review can be used, for example, to control the energy introduced into the welding point and / or the feed rate.

In refinements of the method, a tensile force acting on the flat strip of non-ferrous metal and / or on the welded coaxial cable is determined, and drives that feed the flat strip for forming and / or welding and / or are controlled on the basis of the previously determined tensile force feed the welded coaxial cable to a corrugated or receiving device. Too great a tensile force can lead to the tearing of the belt, especially in the case of fed strips with a very small thickness, which would interrupt the process. The same applies to the tensile force acting on the welded coaxial cable.

A device according to the invention for the continuous production of coaxial cables with a thin-walled, radially closed outer conductor made of non-ferrous metal comprises a supply device set up for supplying a flat strip of the non-ferrous metal. The feed device can, for example, comprise a holder for a flat strip of the non-ferrous metal wound on a spool or a coil. The tape is unwound from the reel and fed to a shaping device, which reshapes the flat tape made of non-ferrous metal into the profile of the hollow profile forming the outer conductor of the coaxial cable so that the opposite edges of the flat tape of the non-ferrous metal butt against one another. The shaping device can, for example, have several rollers and profiles, for example drawing dies, which shape the strip into the desired hollow profile as it passes through in the longitudinal direction. The forming device can also have two or more guide means spaced apart from one another in the longitudinal direction of the formed band or hollow profile, between which the edges are held flush against one another at least at one point to be welded. If necessary, the tape can be guided laterally at one or more points in front of and in the tool in order to minimize lateral movement of the tape. The device also comprises one for feeding one onto the

Dimensions of the hollow profile matched cable core set up feed device. The cable core includes one with a dielectric sheathed inner conductor and possibly further layers. The feed device feeds the cable core at a speed that is matched to the feed speed of the welded hollow profile.

The device further comprises a welding device which welds to one another the edges lying flush against one another between the guide means. The welding device comprises a laser that emits light with a wavelength of less than 600 nm with an energy that causes local melting of the non-ferrous metal on both sides of the edges. As a result of the continuous advance of the reshaped and welded hollow profile or the coaxial cable, areas in which the material has melted move out of the area in which the laser heats the material, and the melted material solidifies again. The energy introduced into the material to heat it is matched to the material, its thickness and the speed at which the hollow profile or the coaxial cable is guided past the welding point, so that the material is located in an area directly against the flush edges is melted, but no liquid material runs into the interior of the hollow profile. The distance between an optical system of the laser and the edges of the hollow profile to be welded can be kept constant via the guide means. In order to keep the position of the edges lying against one another constant in relation to the optics of the laser, a so-called sword can be arranged in front of the guide means which close the longitudinal slot in the longitudinal slot located between the edges in order to prevent spiral twisting. The device also includes one or more feed devices that convey the welded coaxial cable to a corrugator or corrugator, which introduces a screw or parallel corrugation into the outer conductor of the coaxial cable before it is conveyed to a receiving device that picks up the coaxial cable. The feed device can, for example, comprise one or more collet pullers, cleat pullers, disc pullers or tape pullers of known design, with different feed devices also being combined can. Feed devices can be arranged both in front of and behind the corrugator.

In one or more configurations of the device, a measuring device for determining the tensile force is provided in front of the forming device. The determined tensile force can be fed to a control system as an actual value and used with a setpoint to control the drives of the device, for example to control the speed of the feed of the non-ferrous metal strip. In addition, a measuring and / or control device can be arranged behind the welding device, which measures the tensile force exerted on the welded hollow profile or coaxial cable and / or regulates the drive of the feed device, which feeds the welded hollow profile to the receiving device. The control of the pulling force between the feed device and the receiving device can be done, for example, by a dancer, which detects sagging of the welded hollow profile or coaxial cable and supplies corresponding signals to a drive control of the receiving device.

In one or more refinements, the device also comprises a cutting device arranged in front of the forming device, by means of which one or both edges of the fed flat strip of non-ferrous metal are trimmed, the width of the trimmed strip corresponding to the circumference of the hollow profile forming the outer conductor of the coaxial cable . With these configurations, hollow profiles for coaxial cables with different circumferences can be produced without great effort by cutting the supplied metal strip to the required width and adapting the other tools of the device.

Parts cut off at one or both edges of the strip can, in one or more configurations, be fed to a device provided for receiving cut residues.

In one or more configurations of the device equipped with a cutting device, there is a measuring device behind the cutting device for measuring the width of the cut tape provided. The cutting device can be controlled on the basis of the measured values in order to maintain a desired width of the non-ferrous metal strip over a long period of time. Appropriate default values can be fed to the cutting device, with which the measured width of the non-ferrous metal strip can be compared in order to generate a control signal for the setting of the cutting device. The width corresponds approximately to the circumference of the hollow profile, which forms the outer conductor of the coaxial cable, along the neutral fiber.

The welding device can be set up to weld the edges with the required quality even at slow feed speeds of the non-ferrous metal strip.

In one or more configurations, the device also includes a measuring device for determining a temperature profile transversely to the weld seam. The measured temperature profile can be fed to the welding device for controlling the energy emitted, the feed device and / or the feed device for controlling the feed speed.

In one or more configurations, the device also includes a measuring device for measuring at least one dimension of the coaxial cable after welding. This measuring device can be used for integrated quality control, just like a measuring device provided in one or more configurations for checking the weld seam and / or material defects or inhomogeneities in the material. The dimensions can preferably be measured without contact, for example by means of a laser.

In one or more configurations, the corrugated coaxial cable can be sheathed with electrical insulation after it has passed through the corrugator, for example by extrusion coating or wrapping.

With the method described above, in which laser light with wavelengths of less than 600 nm is used to weld thin-walled non-ferrous metal sheets, hollow profiles can easily be used Wall thicknesses below 0.15 mm and diameters or dimensions smaller than 4 mm can be produced at a high quality level without costly post-processing, which are further processed into coaxial cables in the same operation by introducing a cable core. By using focus diameters of the laser beam of less than 400 gm, a sufficiently small heat-affected zone in relation to the dimensions of the hollow profile is guaranteed during continuous welding, so that no material tears occur and a weld seam is produced that does not have a pronounced bead on the inside of the pipe. Because of the direct production of the hollow profile from non-ferrous metal strips with a low

Wall thickness, a subsequent pulling of the pipe to reduce the wall thickness can be dispensed with, which would be problematic because of the cable core located in the interior of the hollow profile in the case of coaxial cables.

With the method described above, coaxial cables with outer conductors with a wall thickness of 0.10 mm at welding speeds greater than 6 m / min can be produced without a drawing process following the welding, whereby the weld seam quality can be kept constant for several hours, so that coaxial cables large lengths can be produced. The smaller wall thickness of the outer conductor of the coaxial cable leads to

Saving of copper and other alloy elements and thus saving valuable resources. A reduction in the wall thickness reduces the laser power required for welding, which in turn results in energy savings or, alternatively, enables the process speed to be increased with the same laser power.

With regard to the finished product, the thinner wall thickness of the outer conductor also proves to be an advantage, as it results in a lower length-related weight, which makes transport and installation easier.

The thinner wall thickness also enables smaller diameters in the formation of the outer conductor. This allows the outer diameter of the cable to be reduced with the same construction. This leads in addition to the further Weight reduction for smaller minimum bending radii and thus more flexibility with regard to laying.

Brief description of the drawing

In the following, the invention is explained in more detail using an embodiment example with reference to the accompanying figures. All figures are purely schematic and not to scale. Show it:

1 an exemplary example of the method according to the invention for the continuous production of thin-walled, radially closed hollow profiles, FIG. 2 an exemplary example of a device according to the invention for the continuous production of thin-walled, radially closed hollow profiles,

3 shows pictures of a weld seam of a hollow profile produced by the method according to the invention, and FIG. 4 shows two exemplary coaxial cables with screw or parallel corrugation.

The same or similar elements are provided with the same or similar reference symbols in the figures.

Execution example

FIG. 1 shows steps of a method 100 for producing coaxial cables with a thin-walled, radially closed outer conductor according to one aspect of the invention. In step 102 of the method, a flat strip of non-ferrous metal is fed to a forming device at a first feed speed. For example, a flat copper tape is unwound from a coil. In the reshaping device, the supplied flat strip is reshaped in step 108 into a shape corresponding to the desired hollow profile of the outer conductor. The reshaping can take place, for example, by means of a roll forming tool. During the reshaping, before the hollow profile forming the outer conductor is completely closed, a cable core is fed which comprises an inner conductor encased by a dielectric and possibly further layers. The cable core can, for example, already be supplied in step 107 immediately before the first forming stage.

Before the reshaping, an optional step 104 can be carried out in a cutting device, in which one or both edges of the strip made of non-ferrous metal are trimmed or prepared in some other way. In this way, even if the edge quality of the strip made of non-ferrous metal is poor, the width of the strip can be set uniformly and precisely and, if necessary, the edges can be prepared for the subsequent welding process. The cutting device can be supplied with measured values from a measuring device which detects the width of the non-ferrous metal strip after cutting. The cut remnants can be picked up in a corresponding pick-up device.

During forming, the edges of the strip are guided by means of guide elements in such a way that twisting before welding is prevented, and the flush edges are guided past a welding device in a defined position and at a defined distance. The guide elements can, for example, comprise one or more Finn shims or guide blades as well as one or more guide bushings which are adapted to the geometry of the hollow profile and which are adapted to the hollow geometry to be produced. The geometry can be closed, for example, by means of drawing dies, locking rings or side roller steps. After forming, two opposite edges of the flat strip are flush with one another in a contact area. In step 110, the edges lying flush against one another in the contact area are continuously welded to one another. The welding is carried out by means of a laser that emits light with a wavelength of less than 600 nm. If necessary, the weld seam can be covered by means of protective gas, adapted to the required weld seam quality. After welding, the coaxial cable with the now radially closed outer conductor is withdrawn from the welding area, step 114, and a screw or parallel corrugation is introduced into the outer conductor in step 119, before the now corrugated coaxial cable is fed to a receiving device for receiving in step 122 . The pulling off takes place by means of a feed device, e.g. by means of a collet puller, cleat puller or tape puller. The feed device can be arranged in front of or behind the corrugator or corrugator; it is also possible to provide two feed devices, one in front of the corrugator or corrugator and one behind it.

To monitor the quality of the weld seam, the temperature profile transverse to the weld seam can be determined in an optional step 112. The determined temperature profile can be fed to a control of the laser and other elements of a device implementing the method, in particular also to one or more drives that regulate the feed speed of the non-ferrous metal strip or the speed at which the welded coaxial cable is pulled out of the welding area becomes.

The method can optionally also include a determination of the tensile force on the band before the reshaping, step 106, and / or on the coaxial cable after the welding, step 120. The determined tensile force can also be fed to the one or more drives as a measured variable for regulation.

The method may also include an optional step 116 in which one or more dimensions of the welded coaxial cable are determined. The dimensions determined can be supplied primarily as input variables for regulating the forming process and the cutting process for setting the width of the strip.

The method can also include an optional step 118, in which the quality of the weld seam and / or the weld metal is non-destructive be checked for material defects, e.g. by means of eddy current testing, ultrasound or X-rays.

The figure does not show subsequent processes by means of which the hollow profile is cut into sections, the coaxial cable is sheathed with an insulating layer or cables are assembled with plugs.

FIG. 2 shows an exemplary example of a device according to the invention for the continuous production of coaxial cables with a thin-walled, radially closed outer conductor. A thin strip 204 made of non-ferrous metal, for example a strip made of copper, is unwound from a roll or unwinder 202. The strip 204 is fed to a roll-forming tool 212, by means of which it is brought into the shape of the desired hollow profile of the outer conductor, for example it is shaped into a longitudinally slotted round tube. A cutting device 208 can be provided between the winder or unwinder 202 and the roll forming tool 212, which cuts the tape 204 to a required width or cuts one or both edges of the tape 204 in order to obtain clean and smooth edges. A receiving device 205 can be provided for receiving cut parts of the tape 204. The width of the cut tape 204 can be checked in a tape width measuring device 210. The measurement results can be fed to the cutting device 208 for control purposes. In addition, a measuring device 206 for determining the tensile force can be arranged between the reel or unwinder 202 and the roll forming tool 212, the measured values of which can be used, for example, to regulate drives of the device. Before the hollow profile forming the outer conductor is closed, a feed device 207 feeds a cable core 209, which is received in the hollow profile after the flat strip of non-ferrous metal has been formed. The edges of the tape lying next to one another after the hollow profile forming the outer conductor has been formed can be guided with one or more guide elements 214 in front of the laser welding device 216 so that the hollow profile is prevented from twisting before welding and the passage distance below an optical system of the laser - Welding device 216 is observed. The guide elements can comprise one or more fin fitting disks or guide blades and one or more guide bushings adapted to the hollow profile forming the outer conductor. The geometry of the hollow profile to be welded is closed by means of drawing dies, locking rings, side roller steps or guide bushings 218, so that the edges of the band 204 formed into the hollow profile lie against one another in the area of the laser welding device 216. The laser welding device 216 emits high-energy light at a wavelength of less than 600 nm, preferably in a range between 550 and 450 nm. Wavelengths in a range below 450 nm can also be used advantageously according to the invention. The welding area can be covered with a protective gas, for example argon, via a protective gas device (not shown in the figure) in order to prevent reactions of the weld metal with the atmosphere. The feed of the welded coaxial cable 224 takes place by means of a feed device 219

Feed device 219 can, for example, comprise one or more collet pullers, cleat pullers, disc pullers or tape pullers, or combinations thereof. Before winding the welded coaxial cable 224 on a winder 226, one or more dimensions of the coaxial cable 224 can be recorded by means of a measuring device 220, preferably without contact, and a screw or parallel corrugation can be introduced into the coaxial cable by means of a corrugator or corrugator 223. To detect the tensile forces acting on the coaxial cable 224, a further tensile force measuring device 222 can be provided in front of the winder 226. FIG. 3 shows pictures of a weld seam of a hollow profile produced by the method according to the invention. The hollow profile is a copper tube with a wall thickness of 0.1 mm, which was continuously formed from a copper strip and welded at a feed rate of 6 m / min. The welding point was covered with argon. FIG. 3 a) shows the weld seam on the outside of the hollow profile, which has a width between 140 and 150 μm. FIG. 3 b) shows a picture of the inside of the hollow profile, on which the weld seam has a width of approximately 242 μm. It is also easy to see that the weld seams Both inside and outside can be very uniform, so that post-processing should not be necessary for most applications.

FIG. 4 shows two exemplary coaxial cables 500, 502 with screw corrugation or parallel corrugation. The coaxial cables 500, 502 are otherwise of conventional construction with an inner conductor 504 surrounded by a dielectric 506 and an outer conductor 508 or 510 corrugated in a helical or parallel manner. The outer conductors 508, 510 are surrounded by an outer insulating layer 512.

Reference list

1 tube 214 guide element

2 Form 216 laser welding device

3 Plugs 218 Drawing die / guide bushes 100 Movement 219 Feed device 102 Feed tape 220 Measuring device

104 Determining tensile force 222 Tensile force measuring device

106 Trimming edges 223 Weller / Corrugator

107 Feed in cable core 224 coaxial cable

108 forming hollow profile 226 rewinder 110 welding 500 coaxial cable

(Screw corrugation)

112 Determine temperature profile 502 Coaxial cable

(Parallel corrugation)

114 Peel off the hollow profile 504 Inner conductor 116 Determine dimensions 506 Dielectric

118 Determine quality 508 outer leader

119 waves 510 outer conductor

120 determine tensile force 512 insulation layer

Feed 122 to the receiving device

200 device 202 reel / unwinder

204 band made of non-ferrous metal

205 Pick-up device for waste

206 Tensile force measuring device

207 feeding device

208 cutter

209 cable core

210 bandwidth

Measuring device 212 roll forming tool

Claims

A method (100) for the continuous production of coaxial cables (224) with a thin-walled, radially closed outer conductor made of non-ferrous metal, comprising: - feeding (102) a flat strip (204) of the non-ferrous metal at a first feed rate to a Forming device (212), the thickness of the strip corresponding to the wall thickness of the hollow profile (224) to be produced,

- feeding (107) an inner conductor sheathed with a dielectric,

- Continuous shaping (108) of the fed flat strip (204) into a shape corresponding to the outer conductor of the coaxial cable (224), two opposite edges of the flat strip (204) being flush with one another after shaping in a contact area extending in the longitudinal direction of the hollow profile abut, and wherein the inner conductor encased by a dielectric is fed in before the hollow profile forming the outer conductor is closed, so that the inner conductor encased by the dielectric lies in the hollow profile,

- Continuous welding (110) of the edges, which are flush with one another in the contact area, without prior treatment

Reduction of optical reflections, wherein the edges to be welded are fed past a welding area which is fixed in relation to a device (200) implementing the method, and where a point in the welding area is heated by means of a laser (216), which light emits a wavelength less than 600 nm, and wherein the heated point has a diameter that is less than 20% of the cross-sectional dimension of the hollow profile,

- pulling (114) the welded coaxial cable (224) out of the welding area,

- Introducing (119) a screw or parallel corrugation in the outer conductor of the coaxial cable (224), and Receiving (120) the coaxial cable (224) in a receiving device (226).

2. The method (100) according to claim 1, wherein at least the welding area flows around or is covered with an inert protective gas during heating.

3. The method (100) of claim 1 or 2, further comprising:

- Trimming (106) one or two edges of the flat strip of the non-ferrous metal before forming.

4. The method (100) of claim 3, further comprising:

- measuring the width of the trimmed strip of the non-ferrous metal before and / or measuring (116) at least one dimension of the coaxial cable (224) after welding, and - regulating the cutting width and / or controlling a device (212) for forming as a function of the measurement result and a default value.

5. The method (100) according to any one of the preceding claims, further comprising:

- Measuring (112) the temperature profile transversely to the weld seam and controlling the energy introduced into the welding area as a function of a comparison of the temperature profile with a default profile.

6. The method (100) according to any one of the preceding claims, further comprising:

Checking (118) the weld seam by means of ultrasound, eddy current measurement and / or X-rays. The method (100) according to any one of the preceding claims, further comprising:

- determining (104, 122) the tensile force on the flat strip of the non-ferrous metal and / or the welded coaxial cable (224), and

- Control of drives that feed the flat strip and / or the welded coaxial cable (224) to the forming, welding, corrugating and / or receiving in a receiving device (226).

Apparatus (200) for the continuous production of coaxial cables (224) with a thin-walled, radially closed outer conductor made of non-ferrous metal, comprising:

- a feed device (202) arranged to feed a flat strip (204) of the non-ferrous metal,

- a feed device (207) set up for feeding an inner conductor (209) sheathed with a dielectric,

- A forming device (212), which forms the flat strip (204) of non-ferrous metal in the profile of the outer conductor of the coaxial cable (224) and around the supplied inner conductor (209) that the opposite edges of the flat strip of the Non-ferrous metal butt flush,

- two spaced-apart guide means (214, 218), between which the edges are held flush against one another,

- A welding device (216) which welds the edges lying flush against one another between the guide means (214, 218), the welding device (216) comprising a laser which emits light with a wavelength of less than 600 nm with an energy that causes local melting of the non-ferrous metal on both sides of the abutting edges

- a feed device (219) which conveys the welded coaxial cable (224) further,

- a corrugator or corrugator (223) for introducing a screw or parallel corrugation into the outer conductor of the coaxial cable (224), and

- a receiving device (226) which receives the coaxial cable (224).

The apparatus (200) of claim 8 further comprising:

- A measuring device (206) arranged in front of the forming device (212) for determining the tensile force acting on the supplied strip (204), the tensile force determined being supplied to control drives of the device (200).

10. The device (200) of claim 8 or 9, further comprising:

- A measuring and / or regulating device (222) arranged behind the welding device (216), which measures the tensile force acting on the welded coaxial cable (224), the measured tensile force being a

Drive of the feed device (219) is supplied for regulation.

11. The device (200) of claim 8, 9 or 10, further comprising:

- A cutting device (208) arranged in front of the shaping device (212), by means of which one or both edges of the fed flat

Band (204) made of non-ferrous metal are cut, the width of the cut band corresponding to the circumference of the outer conductor of the coaxial cable (224) along the neutral fiber. The apparatus (200) of claim 11 further comprising:

- A device (205) for receiving cutting residues.

13. The apparatus (200) of claim 11 or 12, further comprising:

- A measuring device (210) arranged behind the cutting device (208) for measuring the width of the cut flat strip

Non-ferrous metal.

14. The device (200) according to one or more of claims 8 to 13, further comprising: a measuring device for determining a temperature profile transversely to the weld seam, the measured temperature profile of the welding device (216) for controlling the energy output and / or the supply device (202) and / or the feed device (219) for controlling the feed speed is fed.

15. The device (200) according to one or more of claims 8 to 14, further comprising:

- A measuring device (220) for measuring at least one dimension of the coaxial cable (224) after welding (110).

16. The device (200) according to one or more of claims 8 to 15, further comprising:

- A measuring device for checking the weld seam and / or material defects or inhomogeneities in the material.