Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
2000-02-29
2002-07-23
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S036900, C428S935000, C428S939000, C204S198000, C138S145000, C138S146000, C205S230000, C205S233000, C205S237000, C205S205000, C205S220000, C205S181000
Reexamination Certificate
active
06423389
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a metallic-conduit-armored type linear member wherein a linear member such as an optical fiber or an electrical wire, and in some cases a filler material such as a water sealing compound in addition to the linear member, are accommodated in a metallic conduit, a metallic conduit for armoring the linear member, and a method and a system for manufacturing the metallic-conduit-armored type linear member. More particularly, the present invention concerns a metallic-conduit-armored type linear member in which an outer surface of a metallic conduit is coated with metal, a metallic conduit for armoring the linear member, and a method and a system for manufacturing the metallic-conduit-armored type linear member.
BACKGROUND ART
A linear member armored by a metallic conduit is well known as a cable which can be used even in a hostile environment since the metallic conduit is capable of ensuring mechanical strength and environmental resistance. In the case of the metallic-conduit-armored type linear member disclosed in Japanese Patent Examined Publication No. 10805/1988, an optical fiber
51
, which is the linear member, is accommodated in a metallic conduit
52
as a metallic-conduit-armored type linear member
50
shown in the appended FIG.
4
. Such a metallic-conduit-armored type linear member shown in
FIG. 4
is used singly or as an element of a composite cable, such as the one shown in
FIG. 5
, in which other cables or tension members
54
are disposed around it. As one method of manufacturing such a metallic-conduit-armored type linear member, a technique is known in which the extra length of the linear member with respect to the length of the metallic conduit is arbitrarily adjusted to positive, zero, or negative in accordance with the working environment (e.g., Japanese Patent No. 2,505,336). Here, the extra length refers to the difference in the length of the linear member with respect to the metallic conduit, and if the linear member is longer, the extra length is called positive extra length, whereas if the metallic conduit is longer, it is called negative extra length. It should be noted that the ratio of the extra length to the length of the metallic conduit is sometimes referred to as the extra length ratio.
A typical example of secondary processing for imparting an additional function to the metallic-conduit-armored type linear member is the formation of a metallic coating layer on the surface of the armoring metallic conduit (see a metallic coating layer
53
in
FIG. 4
, for example). This metallic coating layer further improves the mechanical strength and environmental resistance which are the functions of the metallic conduit itself. Particularly with respect to the latter, by adopting an appropriate coating metal in the case shown in
FIG. 5
, for example, it becomes possible to prevent electric corrosion due to the difference in the ionization tendency with respect to the metal constituting the cables or tension members
54
surrounding the metallic-conduit-armored type linear member
50
. For example, Japanese Patent Unexamined Publication No. 69,716/1996 discloses a twisted assembly including tension members in which corrosion resistance is enhanced by forming a 5 to 70 &mgr;m-thick aluminum coating layer on the surface of an armoring metallic conduit.
As a typical example of the technique for forming such a metallic coating layer on the outer surface of a metallic conduit, the aforementioned Japanese Patent Examined Publication No. 10,805/1988 can be cited. In this example, as shown in
FIG. 6
, a metallic tape
55
A fed out from a tape supply
55
is formed into a tubular shape in a pipe forming step
57
, in which step an optical fiber
56
A is also concurrently supplied from a fiber supply
56
, thereby forming an optical-fiber-accommodating metallic pipe
58
. Subsequently, after the seam of this pipe
58
is welded in a welding step
59
, the metallic coating layer
53
formed of, for example, aluminum is provided on the outer surface of the metallic pipe
58
by means of vacuum plating such as vacuum deposition, sputtering, ion plating, or the like in a plating step
60
. The vacuum plating is performed continuously with respect to the metallic pipe for which welding has been completed, and the plated metallic pipe is taken off by a takeoff
61
and is taken up by a takeup
62
.
In addition, in Japanese Patent Unexamined Publication No. 2,909/1985, a metallic tape is formed into a tubular shape, and an optical fiber is concurrently supplied to form an optical-fiber-accommodated metallic pipe, and this pipe is immersed in a molten metal bath so as to weld the seam of the metallic pipe and provide a metallic coating layer on the outer surface of the metallic pipe. Further, in the aforementioned Japanese Patent Unexamined Publication No. 69,716/1996, a metallic layer is provided on the outer surface of an armoring metallic pipe in a sintering process or by a chemical or electrochemical method.
However, the following problems are encountered with the conventional techniques. The first problem is that of the thermal effect. As also pointed out in Japanese Patent Unexamined Publication No. 2,909/1985, in a case where the metallic coating layer is formed on the outer surface of the metallic conduit, the fact that the linear member in the metallic conduit receives a thermally adverse effect presents a large problem, and it does not follow that such a thermally adverse effect can be allowed in light of quality assurance just because the coating layer of the optical fiber is apparently not subjected to thermal damage. Particularly in the case where the linear member is a thermally sensitive substance typified by the optical fiber and in the case where a space filler such as a water sealing compound other than the linear member is filled in the metallic conduit, it can hardly be denied that the provision of vacuum plating without adopting some heating preventing means is very dangerous processing which directly leads to the degradation of the quality of the metallic-conduit-armored type linear member. Particularly in a case where it is necessary to form a thick metallic coating layer with a thickness of not several microns or thereabouts but as much as 10 microns or more, surface treatment must be generally effected for a relatively long time, and the possibility of the thermally adverse effect on the substances which are present in the metallic conduit becomes substantially high.
In addition, the thermally adverse effect during the formation of the coating on the metallic conduit surface is also exerted on the metallic conduit itself. Namely, there is a possibility that defective welds which originally existed are further expanded by the thermal expansion of the metallic conduit itself and the thermal shock acting on the metallic conduit, giving rise to new defective joined portions. In the case where a space filler material such as a water sealing compound is contained in the sealed metallic conduit, there increases the possibility that the thermally expanded space filler material jets out from such defective joined portions. Furthermore, even in a case where such a space filler is not present or in a case where a thermally sensitive substance such as the optical fiber is inserted in the armoring metallic conduit after the formation of the metallic coating, the presence or generation, per se, of the defective welds in the metallic conduit constitutes a major problem in terms of the product quality of the metallic-conduit-armored type linear member. In addition, if the plating bath infiltrates into the interior through the defective welds and then solidifies, there is a possibility of causing trouble to the subsequent loading of the linear member and the space filler material. The foregoing problems become no longer negligible in a case where a thick metallic coating layer with a thickness of as much as 10 microns or more is formed on the metallic conduit or in a case where the metallic-conduit-armored type linear
Dawson Robert
Feely Michael J
Kanesaka & Takeuchi
OCC Corporation
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