FR2756641A1 - Optical fibre cable module mfr. machine - Google Patents

Abstract

The machine comprises a station which produces a steel band which is used to make a tube, and a block (1) for supplying optical fibres (2). These sections are followed by a tube-shaping section (3) and a system for injecting grease (4) and a laser welding station (5). A drawing section (6) is provided for calibrating the tube (T) with a drawing capstan (7) and a roller (8). The welding station consists of at least one vertical guide lamella (51) followed by two lateral rollers (53,53') with a channel (531,531') pressing on either side of the tube to close it precisely. The laser beam (55) is directed on to the tube in a plane passing through the axes (Y2-Y2,Y'2-Y'2) of the two lateral rollers.

Description

The present invention relates to a machine for manufacturing optical modules, comprising a sealed metal tube housing optical fibers embedded in a sealant (grease), this machine comprising - a station for emitting steel tape used to produce the
tube, - an optical fiber emission block providing the fibers
optics to be introduced into the tube, - a steel tube forming bench, - a grease injection system in the tube, - a laser welding station receiving the closed tube for the
welding, - a drawing bench downstream of the welding station to calibrate
the tube formed, - a drawing capstan and a winder to pull the tube to
through the machine and wind it up.

 Such a machine is intended for manufacturing optical modules, that is to say a small steel tube with a diameter generally between 1 and 4 mm for a wall thickness of the steel strip from 0.1 to 0.25 mm and containing between 1 and 48 optical fibers.

 The length of such an optical module can be of the order of a few kilometers.

 The optical module thus produced constitutes an element which can be integrated into electrical cables.

 Various embodiments of machines intended in the general sense for welding tubes are already known, for example made of plastic.

 Thus, according to document EP 0 127 127, a method and an installation are known for the manufacture of a tube.

This document describes a machine producing a tube by forming a plastic tape which is gradually bent around the axis of the future tube. The banks are welded using a laser beam.

 The tube formed but not yet welded is held by two tracks, that is to say two endless chains, applied laterally against the tube. These tracks occupy a certain length of tube, upstream and downstream of the welding point.

 Such an installation cannot be transposed to the manufacture of steel tubes of very small dimensions, such as those used in optical modules because there are problems of heating by the laser beam which are practically insurmountable. Indeed, to weld a steel tube you need a laser with a much higher power than that necessary for welding a plastic tube. The heat given off at the weld is therefore very important. As the tube is relatively good conductor as well as the tracks, for these means to withstand the temperature, it is necessary to cool this mobile equipment all the more since the large contact surface with the tube would keep it at a high temperature which would damage the optical fibers. However, the cooling of a track, in order to evacuate large quantities of heat, is a problem difficult to solve for machines for welding optical modules. In addition, although sometimes used in cables, the tracks do not allow precise positioning of the tube to weld it with the laser beam.

 There is also, according to document EP 0 299 123, an apparatus and a method for the continuous manufacture of armored optical cables or optical modules.

 This machine includes a supply of steel tape and fibers as well as sets of rollers for forming the steel tape to obtain a tube.

 Welding is carried out by a laser, that is to say without adding material.

 The problem dealt with in this prior document is that of the precise positioning of the focal point of the laser beam relative to the place where the welding is done, so as to allow the welding to be carried out while avoiding excessively heating the optical fibers to the inside the tube (that is to say under the welding area) to avoid damaging them.

 The means described in this document, to achieve this precise positioning of the focal point of the laser beam with respect to the tube, consist of two guide rollers or rollers, a first guide roller is placed above the tube, upstream of the welding point , and it rotates on a fixed horizontal axis; a second guide roller comes under the tube, loaded by a spring. The second roller applies the tube against the reference surface formed by the first roller.

 Indeed, the first roller being in a fixed position, on the top of the formed tube, it precisely defines the height of the two edges of the tube at the location of this roller but not at the point where the welding takes place while the laser is precisely adjusted to the level of the weld joint defined by the upper roller and not by the edges of the tube at the place where the weld is to be made.

 This installation also has other disadvantages because the edges of the tube are free at the place where the welding is done and the necessary and significant temperature rise, at the point where the welding is done, is reflected upstream of this welding point, in the part of the tube, not held, downstream of the two top and bottom holding rollers. This results in a manufacturing imprecision which is not negligible and above all it is in contradiction with the desired goal, namely that of a very precise manufacturing.

 The present invention aims to remedy these drawbacks and proposes to create a machine for manufacturing the optical modules making it possible to extremely precisely position the blank of tube to be welded to weld it with the laser beam, (without addition of material) under very precise positioning conditions, favorable to the quality of the product to be obtained.

 To this end, the invention relates to a machine of the type defined above, characterized in that the welding station consists of at least one vertical guide blade, located in the longitudinal axis of the machine for guiding the two edges of the tube blank, this guide blade being followed by two lateral grooved rollers pressing on both sides the tube blank to close and hold it precisely, and the beam of the welding station laser is directed on the blank tube to be welded, at the intersection of the tube and the plane passing through the axes of the two side rollers.

 The machine according to the invention, which precisely holds the two sides of the tube blank, prevents them from being able to open or deform while the welding takes place.

The invention makes it possible to hold the tube firmly, in the opposite direction to the forces developed by the stresses exerted by the tube and which tend to open it, as in the known machine which crushes the tube, acting in a direction substantially perpendicular to the direction of the tube opening forces, which tends to rotate the edges of the tube.

 This is extremely important because tests have shown that the precision of the tube obtained does not result from the precision of the position of the hearth relative to the place of the weld to be produced but from the precision with which the two edges of the tube were applied. one against the other at the time of welding.

 As this welding is carried out at the intersection of the plane passing through the axes of the roller and the tube, the welding takes place at the point of maximum approximation of the two rollers, that is to say at the place where the forces of the rollers are the most important.

 In other words, the machine welds the tube blank at the point where its positioning of the tube which is not yet welded is most precise, which makes it possible to obtain a perfect weld of the two edges of the tube which remain aligned one on the other, this avoids inducing deformations in the weld zone.

The present invention will be described below in more detail with the aid of the accompanying drawings in which
FIG. 1 shows an overall diagram of the machine according to the invention,
FIG. 2 is a cross-sectional view along II-II of FIG. 1 showing the positioning and alignment guide,
- Figure 3 is a cross section along III
III showing the preforming rollers,
FIG. 4 is a cross section showing the forming rollers,
FIG. 5 is a sectional view along VV of the alignment guide of the tube blank,
FIG. 6 is a sectional view at the welding point,
FIG. 7 is a schematic top view corresponding to FIG. 6.

 According to Figure 1, the invention relates to a machine for manufacturing optical modules. This machine consists of a transmitting station 1 supplying a steel tape RA shaped into a tube and welded in the machine. It also includes an optical fiber transmission station 2 supplying in parallel the optical fibers Fi which the tube must contain to form the optical module.

 The steel strip RA and the bundle of optical fibers Fi are combined so that the tube gradually surrounds the optical fibers.

 Downstream, the machine includes a tube forming bench 4 and a grease injection system 4. The assembly is followed by the welding station 5 followed by a drawing bench 6. At the outlet of the machine, the tube passes through a drawing capstan 7 before being wound on a winder 8.

 The various peripheral means such as the station for transmitting the steel tape 1, the block for transmitting the optical fibers 2, the capstan for drawing 7 and the winder 8 are only shown diagrammatically, as are the cooling means. from the welding station.

 The machine also includes means for controlling and managing the production. These means are not detailed.

 The various components of the machine will be described below in more detail.

 The transmitting station 1 of the steel strip RA is made up of a support receiving a roller carrying a steel strip the length of the optical module to be produced. This steel strip can for example result from the butt welding of several strips produced separately and which are joined together to obtain the desired length.

 The unwinding of the RA ribbon is controlled according to demand; it passes for example over a puppet by making a loop which controls the unwinding of the RA ribbon.

 These various known means are only represented by rectangle 10.

 At the outlet, the transmitting station includes a positioning and alignment guide 11 of the steel strip RA. This guide 11 is composed of a steel block in two parts, a lower part 111 and an upper part 112 defining between them a passage passage 113, of rectangular section identical to that of the ribbon RA to ensure its transverse guidance. and the exact positioning in relation to the XX axis of the production line.

 FIG. 2 shows a cross section of this positioning and alignment guide 11.

 This guide 11 is inclined relative to the axis XX of the machine corresponding to the movement of the tube between the forming and its traction by the capstan 7 to arrive under the cannula 31 guiding the fibers Fi in the tube being formed.

 The emission block 2 of optical fibers Fi consists, in a manner not shown, of a chassis provided with locations for each receiving a coil carrying a length of optical fibers. These coils are each mounted on an axis driven by a motor also controlled by a puppet on which the optical fiber passes downstream of the coil. This puppet, that is to say this roller, subjects the optical fiber to a loop and ensures the control of the motor driving the reel to unwind the required length of fiber.

 Usually, each coil has only one fiber, at least if the number of fibers to be integrated into the tube is small. On the other hand, to integrate a large number of fibers such as, for example, twenty or even thirty fibers, certain coils or all of the coils carry several fibers.

 The fibers are, like the ribbon, wound on the spools according to the length necessary for the manufacture of the optical module. These various known means are only represented diagrammatically by the rectangle 21. At the outlet of the emission unit all the fibers pass through a coil 22.

 The steel tube forming bench 3 consists of a pair of input rollers 30, 30 'for aligning the strip RA on the axis XX. The upper roller 30 has a groove through which the fibers Fi pass protected by the cannula 31 to touch neither the sides of the roller, nor the ribbon RA.

 According to Figure 3, these rollers 30, 30 'have grooves of different shapes. These two rollers initiate the bending of the RA steel strip. The lower roller 30 'has a flared groove and the upper roller 30 is in the shape of a diabolo with two edges 301, 302 on either side of a central groove 303. The two edges 301, 302 push the ribbon in. RA steel in the groove 301 ′ of the lower roller 30 ′ to raise the edges RA1, RA2 of the tape RA. The upper roller 30 is in contact with the upper face of the tape RA only by the two edges 301, 302, the bottom 304 of the groove 303 of the roller 30 defines with the upper surface of the tape RA an opening 305 serving in one case when the optical fibers Fi and the grease injection cannula 33 pass.

 According to one embodiment, the grease cannula to be injected is introduced into the tube from the rollers 30, 30 '.

In this case, the pump has not been shown.

 The cannula 31 is constituted by a small tube with a section much smaller than that of the tube during manufacture. The cannula is carried by a mobile assembly connected to a high pressure grease pump. The cannula and the moving part can be moved between an operating position and a rest position. In the rest position, the cannula is released from the tube being formed; to get into the operating position, the cannula is moved in translation, carried by its crew so as to be placed substantially in the axis XX of the forming bench (axis of the tube); the cannula arrives over the still flat ribbon leaving the positioning guide 11 to pass between the top of the ribbon and the bottom of the groove 303 of the upper roller 30 of the first set of rollers 30, 30 'and continue beyond the bench forming 3, inside the tube to beyond the welding point.

 The mobile assembly of the grease injection cannula also carries the fiber introduction cannula 31.

This cannula moved at the same time as the fat injection cannula is shorter than the latter. In the working position, the fiber injection cannula can stop downstream of the third set of rollers. This cannula also passes over the ribbon between the bottom of the groove of the upper roller of the first set of rollers to continue inside the tube being formed.

 This cannula has a sufficient section for the free passage of the fibers, while being clearly smaller than the internal section of the tube.

 These fibers are centered by a centering funnel 31A of the cannula upstream of the pair of rollers 30, 30 ′ of horizontal axes and the cannula 31 extends downstream of the third set of forming rollers.

 Downstream, the forming station consists of two preforming rollers 32, 32 'of vertical axes placed on each side of the strip RA. The rollers 32, 32 'continue to raise the edges of the ribbon RA.

 Downstream of the two preforming rollers 32, 32 ', the forming bench comprises two lateral rollers 34, 34' rotating around vertical axes.

According to Figure 4, the rollers 34, 34 'complete the forming of the tube; these two rollers are identical in shape; they each have a groove 340, 340 'between which the ribbon passes
RA which is gradually closed around the optical fibers (cannulas 31, 33). At the outlet of the forming rollers 34, 34 ′, the tube RA is practically closed.

 The complete closure takes place between two rollers 35, 35 ′ of fixed axes, one above and the other below the RA tube blank.

 According to an alternative embodiment shown, between the pairs of rollers 34, 34 'and 35, 35', there arrives a grease injection tube 41 supplied by the pump 42, controlled, forming part of the grease injection system 4. This fat injection system 4, the tube bent by the elbow 43 arrives inside the tube RA during formation, could also be constituted by the cannula 31 of a certain length, also passing through the throat of the roller 30, the cannula being placed in the axis XX of the machine from the roller 30 passing through the groove 323 of this roller as has already been described.

 The outlet 411 of the grease injection cannula 41 opens downstream of the welding point.

 The grease injection pump 42 is a high pressure pump, the flow rate of which is controlled as a function of the parameters of the installation and of the tube to be manufactured (internal volume of the tube per unit of length, volume of the optical fibers, speed of travel , etc.).

The welding station 5 (FIGS. 1, 5, 6, 7) receives the rough tube RA almost closed on itself at the outlet of the forming bench 3. This welding station 5 is aligned on the travel axis XX . It consists at the input, of a transverse guide means formed by one or two thin blades 51 placed one behind the other in the axis XX of travel of the tube. These blades 51 penetrate into the slot F of the tube blank to guide this slot longitudinally; edges T1,
T2 of the tube rest on the sides of the blades 51. The slot F is thus oriented precisely upwards. Under each guide blade 51, the tube is supported by a grooved roller 52.

 This fixed longitudinal guide 51, 52 is followed by two lateral grooved rollers 53, 53 ′, pressing on either side of the tube to close it precisely (FIG. 6).

The welding machine also includes a laser
CO2, 54 installed next to the production line and the beam of which arrives on the tube I, at the junction J of the banks T1, T2 in a direction Y1Yl slightly inclined relative to the perpendicular to the tube T to prevent the laser beam reflected does not penetrate back into the laser. The laser beam 55 meets the tube T at point 56 to weld it.

The output 57 of the laser is supplied with protective gas supplied to the enclosure through the tube 58. (Fig. 1)
In FIG. 7, the scrolling of the tube T is represented by the arrow A.

 The welding point 56 is located at the intersection of a plane passing through the axes Y2Y2 and Y2, Y2 of the rollers 53, 53 'and of the tube T, at the junction of the edges T1, T2. This is the point on the axis of travel XX of the tube blank where the two edges T1, T2 of the tube T are most closely spaced and held most precisely by the two rollers 53, 53 '.

 The welding station 5 is also equipped with a control microscope 59, aiming at the welding point 56 to control it.

 This microscope 59 can receive a video camera which displays the image of the welding zone on a control screen making it possible to verify and ensure the adjustment of the various parameters of the machine.

 Downstream of the welding station, the tube T passes through a drawing bench 6 formed of dies 61, 62 which reduce the diameter of the tube. This reduction can reach up to approximately 40 W.

 The drawing capstan 7 and the winder 8 have only been shown schematically. The drawing capstan 7, downstream of the drawing bench, consists of two pulleys 71, 72 over which the tube T passes several times. One of the pulleys is driven by a servo geared motor to pull the tube through the machine according to a set speed. The winder 8 not detailed, downstream of the capstan, consists of a winding reel on which is wound the tube loaded with fibers and grease constituting the optical module.

Claims (3)

10) Machine for manufacturing optical modules, consisting of a sealed metal tube housing optical fibers embedded in a sealant, machine comprising - a station for emitting the steel tape used to produce the  tube, - an emission block (8) of optical fibers (2) providing the  optical fibers (Fi) to be introduced into the tube, - a forming bench (3) for the steel tube (RA), - a grease injection system (4) in the tube, - a laser welding station ( 5) receiving the closed tube (RA)  to weld it, - a drawing bench (6) downstream of the welding station (5) for  calibrate the formed tube (T), - a drawing capstan (7) and a winder (8) to pull the  tube (T) through the machine and wind it, characterized in that the welding station (5) consists of at least one vertical guide blade (51), located in the longitudinal axis (XX) of the machine for guiding the two edges (T1, T2) of the tube blank (RA, T), this guide blade (51) being followed by two lateral rollers (53, 53 ') with grooves (531, 531') pressing on each side of the tube blank to close it precisely, and the beam (55) of the laser welding station is directed on the blank of tube to be welded, at the intersection of the tube and of the plane passing through the two axes (Y2Y2; Y'2Y'2) of the two lateral rollers (53, 53 ').  2 ") Machine according to claim 1, characterized in that the guide blade (51) is formed of at least two parts placed one behind the other, completed by at least one roller (52) supporting the tube (T). 30) Machine according to claim 1, characterized in that it comprises a control microscope (59) directed on the welding point (56) and equipped with a video camera and a monitor to display the image of the welding of the tube (T).  4) Machine according to claim 1, characterized by a transmitting station (1) of the steel strip (RA) consisting of a transverse guide (11) formed by a section path corresponding to that of the ribbon (RA) for to be crossed by it, this path being inclined relative to the axis (XX) of the machine along which the optical fibers (Fi) travel. 50) Machine according to claim 1, characterized in that the forming bench (3) of the steel tube consists of two superposed input rollers (30, 30 '), receiving the steel strip (RA), and whose upper roller (30) has a groove to allow free passage of the optical fibers (Fi), as well as two pairs of forming rollers (32, 32 ', 34, 34'), a pair of preforming rollers (32, 32 ') followed by a pair of rollers for final shaping (34, 34').