WO1982000222A1

WO1982000222A1 - Method for manufacturing waveguides and waveguides obtained thereby

Info

Publication number: WO1982000222A1
Application number: PCT/FR1981/000091
Authority: WO
Inventors: Cables De Lyon Les
Original assignee: Bocher J; Le Davay L
Priority date: 1980-07-09
Filing date: 1981-07-09
Publication date: 1982-01-21
Also published as: EP0043780A3; EP0043780A2; JPS57501008A; FR2486721B1; FR2486721A1

Abstract

The waveguides are obtained from a metal band (1) shaped and folded until shape is obtained; the edges of the folded and shaped band are welded according to a generating line of the waveguide (4) obtained. Application to the production of long, smooth walled waveguides.

Description

Method for manufacturing waveguides and waveguides obtained.

The present invention relates to a process for the continuous production of smooth-wall waveguides, such as those used for feeders of radio-relay systems, and the waveguides produced by this process.

Current waveguides are generally produced by assembling rigid sections or using flexible corrugated or fluted tubes.

The production of waveguides using rigid sections has a number of well-known drawbacks due to the limited dimensions of the sections and to the form stiffness of these sections if we compare the possibilities offered by these other means. that cables are. In addition, the end-to-end assembly of the sections does not improve the transmission of signals, it is well known that assembly by flanges generates a high standing wave rate.

To overcome these drawbacks, waveguides are conventionally used which are formed either using flexible grooved or corrugated tubes or using semi-rigid tubes. The fluted or corrugated tubes have certain drawbacks and in particular a certain fragility and a significant weakening of the signals transmitted due to the elongation of the paths of the high frequency currents due to the corrugated or fluted profile of the walls. Semi-rigid tubes are conventionally obtained by press extrusion of a ductile metal, such as aluminum; the tube produced by extrusion is normally of circular section and it is known to obtain tubes of different section by crushing the tube. However, the possibilities offered are limited and moreover the crushing of a round profile leads to poorly controlled deformations which do not allow the desired electrical qualities to be obtained.

To overcome these drawbacks, the present invention firstly provides a method of manufacturing waveguides making it possible to obtain waveguides of very great length in continuous, which can be transported on drums like cables and which can be cut into sections of any length during use, and on the other hand the waveguides thus obtained. According to a characteristic of the invention, the manufacturing process comprises the following succession of in-line operations: profiling and folding of a metallic ribbon to the desired closed shape, so that the edges of the ribbon join, the width of the ribbon being chosen or adjusted so as to be equal to the circumference of the guide to be formed;

- edge-to-edge welding of the lips formed by the edges of the ribbon after profiling and folding.

- making a thin adhesive layer on the outside of the waveguide by heating the welded guide, depositing a powdery adhesive copolymer, melting and spreading this adhesive

- production of a thick polyethylene protective layer on the outside of the guide, by extrusion.

According to another characteristic of the invention, the waveguide obtained, which is of the smooth-walled type and which can be rolled up on a reel, is constituted by a profiled metal strip and folded and then welded according to a generator of the guide, and it is covered with a very thick protective polyethylene sheath.

Other objects and advantages of the present invention will be described during the following description and in relation to the figures mentioned below.

FIG. 1 presents a block diagram of a chain intended for the application of the method according to the invention.

Figure 2 shows a longitudinal section of a training tube. Figures 3A and 3B show two cross sections of the training tube.

FIG. 4 presents an example of a train of formation rollers. FIGS. 5A to 5F of examples of section of waveguides obtained by the method according to the invention. The production line shown in Figure 1 shows all the elements necessary for implementing the process for manufacturing a waveguide according to the invention. The metallic ribbon 1, conventionally called strip is generally made of copper or aluminum, it is supplied in the form of a roll which is mounted on a conventional unwinder 2. The width of the ribbon 1 is chosen equal to the circumference of the waveguide that we want to achieve, it being understood that, if necessary, the desired width is obtained by cutting a wider standardized tape.

The strip 1 is introduced into a profiling and folding arrangement 3 which ensures progressive shaping of the metal strip until the desired shape is obtained.

The profiling and folding arrangement 3 is symbolized in FIG. 1 by a formation horn, the shape and operation of which are shown in FIG. 2, it should be understood that other equivalent means can be used to obtain the desired shapes of waveguides and in particular this can also be obtained by means of a train of rollers whose shape and operation are recalled in FIG. 3.

On leaving the arrangement 3, the two lateral edges of the tape 1 are joined due to the deformations undergone, they are then welded to each other, in a preferred variant of embodiment, this is obtained by welding with arc in a neutral atmosphere by means of a welding machine symbolized at 5 in FIG. 1. The welding obtained is preferably carried out according to a generator of the tube 4 formed by the waveguide, this implies that the ribbon is introduced into the axis of the arrangement 3 and not laterally, this in order to avoid having a helical weld bead.

In a preferred embodiment of the waveguides according to the invention, the tube 4 formed by edge-to-edge welding of the strip 1, is heated by any means and for example by induction, to the melting temperature of a copolymer intended forming an adhesive layer, such as an ethylene-ethyl acrylate copolymer.

For this purpose, the tube 4 is sprayed with a rain of particles of the copolymer coming from a tank 7, after having been heated by a heating device symbolized by an inductor 6. The particles melt in contact with the tube and form an adhesive layer which is regulated by a die 8. A extruder 9 extrudes from the tube 4 a. sheath of very thick polyethylene relative to the thickness of the walls of the tube, for example 5 mm of polyethylene on a tube 2 mm in wall thickness, the polyethylene adhering to the layer of copolymer previously arranged.

The sheathed tube 4 is then cooled for example in a tank filled with water such as 10, then wound on a very large diameter reel 11 given the rigidity of the walls of the guide thus formed. FIGS. 5A to 5F show the sections of some of the waveguides which it is possible to obtain, in addition to obtaining a circular section, and in particular sections, such as those presented in 5A, 5B , 5C, 5D, which it is known to obtain by crushing a tube, without here having the drawbacks due to the crushing of the tube. It is also possible to obtain quasi-rectangular sections such as those presented in 5E and 5F.

In fact, the metal tube 4 (FIG. 5A) is closed by a weld 42 only after shaping, which gives a certain freedom to the two edges which form the lips 26 and 27 as long as the weld 42 has not united them. . By cons after welding, the sheath 44 bonded to the tube via the adhesive copolymer 43, reinforces the resistance of the waveguide to the curvature.

Of course, depending on the shapes to be obtained, it may be preferable to use a formation horn as presented in FIG. 2 or a roller train as presented in FIG. 4.

FIG. 2 shows an example of a formation tube 3 seen in longitudinal section, this formation tube 3 comprises a formation channel 23 which is constituted by a series of truncated cones; a calibration section 24 ends the proboscis, it is removable in the example presented and is fixed by the bolts 28 and 29, the assembly being arranged on a table 30. The ribbon 1 passes from a planar shape to a curvature relatively light as shown in cross section 3A in which the ribbon 1 is shown inside the formation horn at the level of section AA. The ribbon 1 is profiled through the formation channel 23 until practically having its final shape, as shown in the section BB in the case of a formation channel 23 intended for the production of oval guides.

The edges 26 and 27 of the ribbon 1 then form lips which are practically contiguous when the ribbon 1 enters the calibration section 24, coming from the forming channel 25.

According to a preferred variant, the ribbon 1 is entered into the tube so that the deformations are symmetrical and the edges meet in parallel when the final shape of the waveguide is obtained at the level of the calibration section. Of course the edge welding which is carried out by the welding machine 5 is preferably carried out to obtain the best possible electrical results while taking into account the obligations imposed by the possible curvatures given to the waveguide during installations. In the case where the selected section of the waveguide is that of a more or less flattened oval as shown in FIG. 5, the welding is carried out according to a generatrix arranged in a plane of symmetry of the waveguide, this plane containing for example the major axis of any cross section of the guide. To this end, an effort is made to maintain the median axis of the ribbon 1 constantly on the same generator G of the formation channel 23 during forming, this implies that this generator G is parallel to the direction of movement of the ribbon 1 and that the ribbon 1 comes tangentially to it. In the case presented, this generator G is arranged parallel to the plane of the table 30 which carries the proboscis 3, the ribbon 1 moving parallel to this table plane 30.

FIG. 3 shows an example of rollers intended to ensure shaping in place of the forming tube. In a known manner, the ribbon 1 must pass through a train composed of pairs of successive rollers such as the rollers 32 and 33 which are mounted on bearings 34 and 35 arranged on shafts 36 and 37 themselves fixed on a frame 38, the shaft 37 being movable under the action of pressure means 39, in order to ensure a determined pressure on the ribbon 1 which circulates between the rollers 32 and 33. The two rollers of a pair 31 and 32 have complementary shapes which determine the shape which is taken by the tape 1 after passing between them.

The use of successive pairs therefore makes it possible to obtain the desired shapes within the limits well known to those skilled in the art.

Claims

1 / A method of continuously manufacturing a waveguide with smooth walls, characterized in that it comprises the following succession of in-line operations: - profiling and folding of a metallic strip (1) in the closed form desired, so that the edges of the ribbon join, the width of the ribbon being chosen or adjusted so as to be equal to the circumference of the guide to be formed;

- edge-to-edge welding of the lips formed by the edges (26, 27) of the ribbon after profiling and folding;

- Making a thin adhesive layer (43) on the outside of the waveguide by heating the welded guide, depositing a powdery adhesive copolymer, melting and spreading this adhesive, making a thick protective layer by polyethylene (44) on the outside of the guide, by extrusion.

2 / Waveguide with smooth walls, characterized in that it is constituted by a profiled and folded metal strip, then welded according to a generator of the guide and in that it is covered with a protective sheath of very thick polyethylene.