Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/46—Processes or apparatus adapted for installing or repairing optical fibres or optical cables
  • G02B6/48—Overhead installation
  • G02B6/483—Installation of aerial type
  • G02B6/486—Installation of aerial type by helical wrapping
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/20—Bonding
  • B23K26/21—Bonding by welding
  • B23K26/24—Seam welding
  • B23K26/26—Seam welding of rectilinear seams
  • B23K26/262—Seam welding of rectilinear seams of longitudinal seams of tubes
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
  • G02B6/4479—Manufacturing methods of optical cables
  • G02B6/4483—Injection or filling devices
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
  • G02B6/4479—Manufacturing methods of optical cables
  • G02B6/4484—Manufacturing methods of optical cables with desired surplus length between fibres and protection features
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
  • G02B6/4479—Manufacturing methods of optical cables
  • G02B6/4486—Protective covering
  • G02B6/4488—Protective covering using metallic tubes

Definitions

• the invention relates to a method and an apparatus for manufacturing long optical modules capable of transporting optical signals in any medium, which may be solid, liquid or gaseous. These modules are then assembled with possibly other elements of other kinds ( electrical conductors or load-bearing elements for example) to form a cable.
• modules are currently used in many industries, particularly in the field of telecommunications. They comprise a waterproof metal tube, generally made of steel, in which are placed one or more optical fibers embedded in a sealant such as a gel or a grease.
• a sealant such as a gel or a grease.
• the metal tube is obtained from a metal ribbon which first passes through a first series of forming rollers giving the ribbon the shape of a partially formed tube and having a longitudinal slot.
• the optical fibers are then introduced from above through this slot, then the partially formed tube is passed through a second series of forming rollers which gives it the form of a closed tube having a longitudinal joint line.
• the tube is then laser welded along the joint line.
• the fibers are introduced through a guide tube into which a carrier gas is also injected. This guide tube extends to the point of tangency of the metal tube with a capstan used to ensure the traction of the metal tube.
• a sealant injection tube follows a similar path to that of the guide tube and extends on the capstan beyond the guide tube.
• the apparatus described in document EP-A-0 299 123 is intended to introduce an extra length of fibers inside the metal tube, in order to prevent these fibers from being tensioned during their use.
• the tension applied to these fibers by the capstan undergoes uncontrollable variations.
• the temperature of the metal tube heated by forming varies during the operation of the device, especially at the start of manufacture, which is not taken into account by the device.
• the apparatus described in this document also does not take into account the fact that, for a given capstan, the excess length of fibers relative to the metal tube depends on the diameter of the latter.
• the device described in document EP-A-0 299 123 does not, in practice, make it possible to control with precision its accuracy the length ratio actually existing in the cable. optical manufactured between the optical fibers and the metal tube. As a result, in the operating temperature range of these optical modules, undesirable stressing of the optical fibers detrimental to good transmission of the optical signals is practically inevitable. Also, the apparatus described in document EP-A-0 299 123 does not achieve satisfactory filling of the metal tube with the sealant either. Indeed, the product is introduced into the tube beyond the point of tangency of the latter on the cabes ⁇ tan and it is not possible to control the filling. Consequently, in order to avoid a rise in the product in the metal tube up to the welding station of the latter, underfilling must imperatively be carried out.
• the invention mainly relates to a given pro ⁇ and an apparatus for manufacturing the optical modules continuously maintaining precise and adjustable control of the ratio of the lengths between the optical fibers and the metall tube that this rappc r: lengths being determined as a function of the operating conditions of the cable, in particular the range of operating temperatures of this cable and its traction in use, in order to guarantee optimal operation of the latter by limiting at best the constraints borne by the optical fibers.
• the subject of the invention is a process and an apparatus for manufacturing optical modules continuously, in which the quantity of sealant introduced into the metal tube is controlled, in order to guarantee filling of the complete tube and without excess.
• the first objective is achieved by a method of fab ⁇ 'ca- tion optical module comprising a sealed metal tube in which is received at least one optical fiber embedded in a sealant, characterized by the fact that it comprises the following stages: - introduction of the optical fiber into a straight line guide tube, at a controlled introduction speed; - progressive forming of said metal tube around the guide tube, from a metallic tape, until a closed tube is obtained having a longitudinal joint line; - welding of said closed tube along the longi ⁇ tudinal joint line;
• the second preceeded objective is also achieved by the fact that this method further comprises the following steps:
• an apparatus for manufacturing optical modules comprising a sealed metal tube in which is received at least one optical fiber embedded in a sealant. characterized by the fact that it includes:
• this apparatus further comprises means for introducing a neutral gas into the welded metal tube, via an inlet pipe juxtaposed with the pipe for injecting the sealant and opening upstream of this pipe; means for measuring the pressure of the neutral gas in the inlet pipe; and means for regulating the rate of injection of the sealant as a function of sudden variations in the measured neutral gas pressure resulting from the sealing of this inlet pipe.
• means for drawing the welded metal tube and means for cooling this tube are placed between the welding means and the measuring means.
• the quality of the weld is checked, for example, by means of detection of eddy current faults.
• FIG. 1 is a partial and very schematic Longitudina sectional view of part of an apparatus for manufacturing optical modules according to the invention, illustrating the principle of making an optical cable at means of this apparatus (the ratio between the diameter of the cable and its length is voluntarily amplified to facilitate the reading of this figure);
• FIG. 2 schematically illustrates the entire kinematic chain of the device l according to the invention, the part of this device illustrated in Figure 1 not being shown;
• - Figure 3 is a sectional view on a larger scale along the line III-III of Figure 1;
• FIG. 4 is a sectional view on a larger scale along the line IV-IV of Figure 1;
• FIG. 5 is a sectional view on a larger scale along the line V-V of Figure 1;
• FIG. 6 is a sectional view on a larger scale of scale along Line VI-VI of Figure 1;
• FIG. 7 is a side view in section illustrating on a larger scale one of the dies of the apparatus illustrated in Figure 1;
• FIG. 8 is a sectional view along line VIII-VIII of Figure 7;
• FIG. 9 is a side view in section illustrating the part of the apparatus of Figure 1 located immediately downstream of the welding means;
• - Figure 10 is a schematic view, in cou ⁇ pe, the capstan of arrival of the fibers on the apparatus l;
• Figures 11 and 12 are sectional views comparable to Figure 8 i llustrant two alternative embodiments of the invention.
• the apparatus for manufacturing optical modules illustrated in the figures is designed such that the ratio between the lengths of the metal tube and of the optical fiber constituting the optical module obtained has a precise value predetermined as a function of the operating conditions of the cable, in particular the operating temperature range of this cable and its use traction.
• the precision to be obtained in the length ratio is of the order of 0.0001.
• this ratio is slightly less than one, that is to say that the fiber is in excess length relative to the metal tube. In certain cases, however, this ratio can be greater than one, in particular when the module must be used at low temperature.
• This part of the apparatus is designed in order to introduce one or, more generally, several optical fibers F inside a welded metal tube T, usually made of stainless steel, without the fibers F undergoing any deviation tion of their journey during their introduction.
• the part of the apparatus illustrated in FIG. 1 comprises a rectilinear guide tube 10, arranged horizontally in the example shown.
• the optical fibers F are introduced into the guide tube 10 by a flared end 10a of the latter, under the ac ⁇ tion of appropriate introduction means, constituted in the embodiment represented by a track for the introduction of fibers 12.
• the caterpillar for introducing fibers 12 comprises two conveyors 12a and 12b defining between them a horizontal contact plane situated in the extension of the axis -of the guide tube 10 and the fibers F are pressed between these conveyors so as to be able to be driven by them towards the end 10a of the guide tube 10, which is in the immediate vicinity of the caterpillar for introducing fibers 12.
• One of the conveyors of the fiber introduction track 12, for example the lower conveyor 12b, is driven at a speed controlled by a self-synchronous motor 14. As will be seen later, the actuation of this motor 14 is constantly controlled so that the introduction of the fibers F inside the tube T makes it possible to obtain the desired length ratio between them.
• the part of the machine illustrated in FIG. 1 also comprises means making it possible to gradually form the tube T around the optical fibers F apart from a metal ribbon R whose width is slightly greater than the circumference of the tube of the optical cable that we want to manufacture.
• the metal strip R is delivered by a reel 15 driven in rotation by a geared motor 17 comprising a DC motor. After having walked on a puppet 19 with position control allowing to regulate the flow, then on return pulleys 16, the metal strip R circulates parallel to the axis of the guide tube 10 and in the same direction as the fibers F, immediately below the guide tube and close from the end 10a by which the fibers are introduced into the latter.
• the metal strip R passes through a lateral positioning die 18 which is shown in more detail in FIG. 3.
• This die 18 comprises a lower part 20 and a upper part 22 forming between them a horizontal passage 23, the rectangular section of which corresponds to the section of the ribbon R.
• the upper part 22 further comprises a central recess 22a opening into the passage 23 and through which the guide tube 10 passes.
• This die 18 ensures very precise height and lateral positioning of the metal strip R relative to the guide tube 10, without requiring any deviation of the straight line path followed by the latter and by the fibers for which it provides gui ⁇ dage.
• the metal strip R passes through means making it possible to form the metal tube T progressively from the strip R.
• these progressive forming means first of all comprise a pair of rollers 24 and 26 for preforming the lateral edges of the ribbon R.
• the axes of the rollers 24 and 26 are placed in the same vertical plane and arranged parallel to one another and to the horizontal plane formed at this point by the ribbon R.
• the upper roller 24 is placed above the ribbon R and it has in its central part an annular groove 24a allowing the passage of the straight guide tube 10 without any deviation from the trajectory of the latter.
• the lateral edges of the upper roller 24 have a convex section in the form of arcs of a circle of approximately 90 ° whose radius corresponds approximately to the radius which is desired to be given to the metal tube T at the right of the welding station.
• the lower roller 26 is placed below the metal strip R and it has on its lateral edges a concave section in an arc of a circle complementary to the section of the lateral ends of the upper roller 24.
• the assembly formed by the rollers 24 and 26 thus makes it possible to preform the lateral edges of the ribbon R, as illustrated in FIG. 4.
• the ribbon R whose edges have been preformed by the rollers 24 and 26 then pass between two rollers 28 for preforming the tube.
• These two rollers 28 are completely identical and placed on either side of the ribbon R, their axes being arranged in the same vertical plane oriented transversely with respect to the ribbon, these axes also being vertical and parallel to one another.
• the outer surfaces of the rollers 28 are concave surfaces having in section the shape of an arc of a circle slightly less than 180 ° and whose radius is approximately equal to the diameter of the metal tube at the right of the welding station. As illustrated well in FIG. 5, the rollers 28 make it possible to curve the central part of the metallic strip R to give the latter the form of a blank of tube open on the top and partially closed around the guide tube 10 by which are introduced optical fibers.
• the blank of the tube passes between two rollers of gold enta ion 30 and 32, the horizontal and parallel axes of which are disposed respectively at above and below the blank and in the same vertical plane.
• the lower roller 32 has in section the shape of an arc of a circle of slightly smaller radius than the preforming rollers 28.
• the upper roller 30 comprises a projecting part 30a, of section in the form of an isosceles trapezoid, on the flanks of which bear the lateral edges of the longitudinal slot still formed on the blank of the tube. This slot is thus perfectly oriented upwards and centered relative to the vertical plane containing the axis of the blank of the metal tube.
• the ribbon R passes successively through two dies 34 and 36 whose internal diameters are decreasing, which has for the effect of gradually closing the ribbon R around the guide tube 10.
• the inside diameter of the second die 36 is such that the metal ribbon emerging from this die has the form of a closed tube T, the lateral edges of which are in contact with one another along a longitudinal joint line L arranged along the upper generatrix of the tube T.
• the dies 34 and 36 are by example of diamond dies which therefore enable the final shaping of the tube to be carried out in a closed circular section.
• the tube T thus formed by the dies 34 and 36 surrounds the straight line guide tube 10 through which the optical fibers F. are introduced.
• the closed tube leaving the die 32 then passes in front of a welding station 38.
• This welding station 38 comprises, for example, a CO2 laser 0, shown very schematically on FIG. 1, which emits a laser beam directed towards the longitudinal joint line of the tube T and focused slightly above this line by a focusing optics 42.
• the edge-to-edge welding of the metal tube that T is carried out without addition of material, under an argon atmosphere.
• the part of the laser beam located near the tube T is surrounded by a casing 44 in which argon is injected by a pipe 46.
• a casing 48 is also placed around the tube T at the right of the welding station 38 and a pipe 50 also makes it possible to inject argon into this casing 48.
• Argon is also injected into the interior of the metal tube T, slightly downstream of the welding zone.
• argon is introduced through a pipe 52 which travels arrival- pa ⁇ ralloxyment the guide tube 10 in the finely lateral positioning of die 18 and in the encoc h e 24a formed in the roller 24, to open in the tuoe-guide 10 upstream of the rollers 28.
• the metal tube T is positioned at the location of the welding station 38 by two pairs of holding rollers 54 and 56 placed respectively upstream and downstream of the casing 48, the rollers of each pair of rollers being placed on either side of the metal tube so that their vertical axes are mutually parallel and located in the same transverse plane with respect to the tube T.
• the rollers 54 and 56 have on their outer surfaces a concave profile having in section the shape of an arc of a circle whose radius is equal to the outside radius of the tube T leaving the die 36. Referring again to FIG. 1, it can be seen that the welded tube leaving the welding station 38 passes then in several diamond chains 58 whose inner diameter gradually decreases.
• the part of the device shown in FIG. 1 also includes means for continuously introducing a sealant inside the welded tube T in order, on the one hand, to ensure the longitu ⁇ dinal sealing of the module optical and, on the other hand, to prevent a longitudinal movement of the optical fibers F inside the tube T, which could cause variations in the ratio of lengths between the fibers and the tube obtained by the apparatus. according to the invention.
• the sealant G is introduced into the tube T by an injection pipe 60 which penetrates laterally inside the tube being formed, between the two pairs of rollers 24, 26 and 30, 32, approximati ⁇ ement at the level of the rollers 28, through the longitu ⁇ dinal opening which exists at this level at the upper part of the tube being formed, between the lateral edges of the metal strip R.
• the injection pipe 60 opens out to the inside the tube T slightly downstream from the corresponding end of the guide tube 10, in the immediate vicinity of the inlet of the first die 58 (FIG. 9). As shown in particular in FIG. 8, the injection pipe 60 has, inside the tube T during forming, then welding, a bean-shaped section surrounding the guide tube 10.
• the optical module which leaves the dies 58 is cooled by a cooling circuit 62 with water circulation of any conventional design.
• Various measurements are then carried out on the optical module thus cooled, in order to allow, in accordance with the invention, continuous control of the ratio between the lengths of the fibers and the tube for a given average temperature of use.
• the optical module advancing by means of the element at its axis thus firstly crosses a first temperature measurement system 64, a system 66 making it possible to continuously measure the running speed of the tube, by means of a roller 68 held elastically only in contact with the outside surface of the tube, and a second system 70 for measuring the temperature of the tube.
• the optical module C0 then passes through a defect detector consisting of a coil 72 with eddy currents making it possible to control the quality of the weld produced on the tube by means of a control station 74 connected to the coil 72.
• the linear movement of the tube T in the device is obtained by exerting a tensile force on this tube, downstream of the coil 72, by means of a cabes ⁇ tan 76 driven in rotation by a self-synchronous motor 78.
• a force sensor shown schematically at 80 is associated with the capstan 76 to permanently measure the tensile force actually applied to the tube by the latter.
• the signals delivered by the temperature measurement systems 64 and 70, the tube speed measurement system 66 and the force sensor 80 are transmitted to a central control unit 82.
• the central control unit 82 receives by information the information supplied by an operator by means of a console 84. This information relates in particular to the length ratio between the optical fibers and the tube metal of the optical module that one wishes to manufacture, the coeffi ⁇ cient of latation, the elastic modulus of the metal used and the geometry of the tube produced.
• the console 84 determines, by means of a preset program, the instantaneous value of the speed at which the optical fibers must be introduced into the guide tube 10. This instantaneous value is continuously transmitted to the self-synchronous motor 14 controlling the pathway for the introduction of the fibers 12, in order to ensure it automatic correction.
• the optical module C0 After having traversed approximately 3/4 of a turn on the capstan 76, the optical module C0 is wound on a reel 86 driven in rotation by a geared motor 88.
• a dummy with position servo 90 is interposed between the capstan 76 and the reel 86 in order to keep constant the voltage applied to the optical module at the output of the capstan 76.
• the injection of the sealant by the injection pipe 60 is controlled by an injection pump 92 (FIGS. 1 and 2) controlled by an auto-synchronous motor 94.
• This motor 94 is controlled by an emitted signal by the control center 82, in response to the signals supplied by a pressure sensor 96 placed in the argon inlet pipe 52.
• the pressure of argon detected by the sensor 96 is equal to the pressure of the argon injected by the inlet pipe 52.
• the flow rate of the sealant being initially slightly in excess, it tends to flow back towards upstream relative to the end of the injection pipe 60. After a certain time, it therefore obstructs the end of the guide tube 10 through which the argon is introduced into the welded tube (FIG. 9) . This results in a sudden increase in the argon pressure detected by the sensor 96.
• the control unit 82 issues an order to decrease a given value d of the product injection rate d seal, which is transmitted to the self-synchronous motor-94.
• control unit 82 issues an order having the effect of increasing the sealant flow rate equal to ⁇ d / 2.
• the apparatus according to the invention is also designed so that all the optical fibers which are placed inside the same metal tube T have exactly the same length, so that the ratio between the fiber length and the tube length is exactly the same for each of the optical fibers.
• each of the fibers F is introduced into the fiber introduction track 12 with a constant tension which is identical from one fiber to the other.
• this result is obtained by unwinding each optical fiber F from a separate coil 98, by means of a DC motor 100 associated with this coil, then by making pass the fiber over a puppet 102 with position slaving, ensuring precise adjustment of the tension of the ibre. This tension is calculated so as to ensure the same elongation of all the fibers.
• Each of the fibers F is then directed to a single capstan 104, placed i medially upstream of the introduction track of the fibers 12, by deflection pulleys, and makes about 3/4 of a turn on this capstan.
• the capstan 104 is equipped with an encoder 106 making it possible to continuously measure the length of fibers penetrating the path. nor a fiber introduction bead 12.
• This capstan is a multi-stage capstan intended to position the neutral fibers of the optical fibers F1, F2, F3 on the same diameter, independently of the diameter of these fibers, (see FIG. 10). All of these means associated with the fact that the resistant torque is negligible ensures the equality of the lengths of the fibers when they are out of stress.
• the information provided by this encoder is also transmitted to the control center 82, which makes it possible to guarantee "The introduction of the fibers into the metal tube at the desired speed, by compensating for the possible slippage of the track. introduction of fibers 12.
• the apparatus for manufacturing optical modules according to the invention makes it possible to control in real time the relationship between the length of the optical fibers F and the length of the metal tube T in the current optical module. manufacturing, taking into account the temperature at which the tube is leaving the cooler 62.
• This produces automatic and continuous optical modules in which the relative length of the optical fibers is controlled with very high precision .
• this relative length of the fibers can be given variable values and possibly made to vary during the manufacture of the same optical module. This last possibility is very interesting in particular as regards the production of cables intended to work vertically under the traction of their own weight. In that case.
• the elongation of the cable is variable, maximum elongation in the upper part of the cable and minimum in the lower part, it is then possible to take account of the variations in elongation of the cable to correct the value of the relative length of the optical fibers when manufacturing the module optical so that, for example, this relative length is constant in the cable installed.
• the apparatus according to the invention ensures complete filling of the metal tube without excess, with the sealant, which allows the latter to fulfill its function under the best possible conditions.
• the invention is not limited to the embodiment which has just been described by way of example, but covers all its variants.
• the introduction of the fi ⁇ ber into the guide tube can be carried out by means different from the cheni lle for introducing the fibers described.
• the CJ flow control njec ⁇ tion of the sealant which is made through the detection of the sealing of the guide tube, can be done according to a different cycle from that which has been described.
• the injection pipe 60 for the sealant can be placed around the straight line guide tube 10 through which optical fibers are introduced (FIG. 11) or be connected directly. on this guide tube (figure 12). In both cases, the argon inlet pipe then opens slightly upstream of the guide tube, but downstream of the welding means.
• rollers 30 and 32 can, in some cases, be removed. It is the same for the rollers 28 if the sealant, instead of being introduced by the bent tube 60, is introduced and pushed into a long straight tube, before any forming of the tube T, upstream of the fi 18.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Plasma & Fusion (AREA)
• Mechanical Engineering (AREA)
• Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

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• 1989
  • 1989-07-24 FR FR8909938A patent/FR2650081B1/fr not_active Expired - Lifetime
• 1990
  • 1990-07-23 WO PCT/FR1990/000558 patent/WO1991001506A1/fr not_active Ceased
  • 1990-07-23 CA CA002037040A patent/CA2037040A1/en not_active Abandoned
  • 1990-07-23 EP EP90912692A patent/EP0436014A1/de not_active Withdrawn
  • 1990-07-23 US US07/659,426 patent/US5143274A/en not_active Expired - Fee Related

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