Metal fusion bonding – Process – With condition responsive – program – or timing control
Patent
1991-03-20
1992-09-01
Heinrich, Samuel M.
Metal fusion bonding
Process
With condition responsive, program, or timing control
228148, 228 9, 228 175, B23K 3102, H04B 900
Patent
active
051432749
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention relates to a process and an apparatus making it possible to manufacture very long optical modules able to transport optical signals in a random medium, which can be solid, liquid or gaseous. These modules are then assembled optionally with components of other types (e.g. electrical conductors or carrier elements) in order to form a cable.
Such modules are presently used in numerous industries and in particular in the telecommunications field. They comprise a tight metal tube, generally made from steel, in which are placed one or more optical fibres embedded in a sealing product such as a gel or grease.
EP-A-0 299 123, proposes a process and an apparatus making it possible to continously manufacture such optical modules. According to this process, the metal tube is obtained from a metal ribbon, which firstly passes into a first series of shaping rollers giving the ribbon the shape of a partly formed tube and which has a longitudinal slit. The optical fibres and then introduced from above through said slit. The partly formed tube is then passed into a second series of shaping rollers, which gives it the shape of a closed tube with a longitudinal joint line. The tube is then laser welded along the joint line.
In one of the embodiments described in EP-A-0 299 123, the fibres are introduced by a guide tube, into which is also injected a carrier gas. This guide tube is extended up to the contact point of the metal tube with a capstan, which ensures the tension of the metal tube. A sealing product injection tube follows an identical path to that of the guide tube and on the capstan is extended beyond said guide tube.
Although the general production principle disclosed in said document is satisfactory, the apparatus described and claimed therein does not really take account of the particular difficulties resulting from the brittleness of optical fibres, which are only able to withstand minimum mechanical stresses, otherwise there is a reduction in the transmission quality of the optical signals through the said fibres.
Thus, the apparatus described in EP-A-0 299 123 introduces an extra length of fibres into the metal tube, so as to ensure that these fibres are not tensioned during use. However, as the fibres are introduced from above into the partly formed tube, the tension applied to these fibres by the capstan is subject to uncontrollable variations. Moreover, the temperature of the metal tube heated by the shaping process varies during the operation of the apparatus, particularly at the start of manufacture, which is not taken into account by the apparatus. Finally, the apparatus described in this document also does not take account of the fact that, for a given capstan, the extra length of fibres compared with the metal tube is dependent on the diameter of the latter.
As a result of these uncontrollable variations and imprecisions, the apparatus described in EP-A-0 299 123 does not make it possible to sufficiently accurately control or check the length ratio in the manufactured optical cable between the optical fibres and the metal tube. Thus, in the temperature range in which these optical modules are used, there is an undesirable stressing of the optical fibres, which is prejudicial to a good transmission of the optical signals.
Moreover, the apparatus described in EP-A-0 299 123 does not bring about a satisfactory filling of the metal tube by the sealing product. Thus, the product is introduced into the tube beyond the contact point of the latter with the capstan and it is not possible to check the filling. Consequently in order to prevent a rise of the product in the metal tube up to the welding station for the latter, it is necessary to carry out an underfilling.
The present invention mainly relates to a process and an apparatus making it possible to continuously manufacture modules, whilst permitting a precise and adjustable checking of the length ratio between the optical fibres and the metal tube, said length ratio being determined as a function of the cable operating conditi
REFERENCES:
patent: 4372792 (1983-02-01), Dey et al.
patent: 4741470 (1988-05-01), Winter et al.
patent: 4852790 (1989-08-01), Karlinski
patent: 4949894 (1990-08-01), Winter et al.
patent: 5007703 (1991-04-01), Hale et al.
Bretheau Dominique
Chapelet Franck
Laupretre Jean-Jacques
Heinrich Samuel M.
Societe Foptica S.A. & Commissariat a l'Energie Atomique
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