US3816641A

US3816641A - Underwater connector and method of making same

Info

Publication number: US3816641A
Application number: US00359911A
Authority: US
Inventors: R Iversen
Original assignee: Viking Industries
Current assignee: CIT Group Credit Finance Inc
Priority date: 1973-05-14
Filing date: 1973-05-14
Publication date: 1974-06-11
Anticipated expiration: 1991-06-11

Abstract

An underwater connector for communication cables, which can be readily installed in the field and which provides long term high reliability at great undersea depths. The connector includes a tubular preform of the same thermoplastic material as the sheath of the cable and which is heat-bonded to the cable so that the materials of the preform and cable sheath merge. The preform has a flange near its forward end which is installed facewise against the rear end of a metal shell into which the cable extends, and a cap threaded onto the shell presses against the rear face of the flange to lock it in place against the shell. The conductors of the cable extend through a hard member which abuts the extreme forward ends of the preform and cable sheath to prevent either of them from being forced further into the shell under the high underwater pressures.

Description

United States Patent Iversen 1 UNDERWATER CONNECTOR AND METHOD OF MAKING SAME Inventor: Ralph T. Iversen, Granada Hills,

Calif.

Assignee: Viking Industries Inc., Chatsworth,

Calif.

Filed: May 14, 1973 Appl. No.: 359,911

[56] v References Cited UNITED STATES PATENTS 4/1942 Machlett et a1 174/75 D X 6/1946 McCutchan 174/76 l/l953 Frazee 174/77 S 8/1955 Parish 174/77 R X 9/1955 Lidderdale 174/77 R Primary Examiner-Laramie E. Askin Attorney, Agent, or Firm-Lindenberg, Freilich & Wasserman I [57] ABSTRACT An underwater connector for communication cables, which can be readily installed in the field and which provides long term high reliability at great undersea depths. The connector includes a tubular preform of the same thermoplastic material as the sheath of the cable and which is heat-bonded to the cable so that the materials of the preform and cable sheath merge. The preform has a flange near its forward end which is installed facewise against the rear end of a metal shell into which the cable extends, and a cap threaded onto the shell presses against the rear face of the flange to lock it in place against the shell. The conductors of the cable extend through a hard member which abuts the extreme forward ends of the preform and cable sheath to prevent either of them from being forced further into the shell under the high underwater pressures.

8 Claims, 6 Drawing Figures UNDERWATER CONNECTOR AND METHOD OF MAKING SAME BACKGROUND OF THE INVENTION This invention relates to underwater cable connectors.

Underwater telephone cables must often be spliced to one another or joined to other undersea equipment by crews of a maintenance vessel. A variety of cable types may be used, including coaxial cables and those with solid conductors, but most cables utilize a surrounding sheath of a thermoplastic material such as polyethylene to provide flexibility and high resistance to corrosion. Connections of cables to one another or to repeaters or to other equipment can be reliably made within shells of a metal that resists corrosion. However, it has been difficult to form a reliable seal at the location where the cable enters the metal shell, which can be assured of remaining water tight over a long period of service. One problem is that the thermoplastic material cannot be readily bonded to metal of the shell. In addition, the very great difference in pressure between the surrounding sea water and the atmosphere within the metal shelltends to cause the cable any any sealing device to be pushed into the metal shell. One technique that has been employed to seal the cable sheath to the shell included the use of a sealing member which was chemically bonded to the cable sheath and which was sealed by epoxy cement and a tightening clamp to the sheath. That type of connection is difficult to reliably install in the field so as to assure great reliability at extreme high undersea pressures that are encountered at the greatest ocean depths.

SUMMARY OF THE INVENTION In accordance with one embodiment of the present invention, an underwater cable connection is provided which can be readily constructed in the field and which is highly reliable for use at great ocean depths. The connection includes a tubular preform disposed about an end of the cable, the preform constructed of the same thermoplastic material as the cable sheath and heat bonded tothe sheath so that the material of the preform and sheath merge into one another. The preform has an outwardly extending flange at a forward end thereof which is nearest the cut end of the cable. The forward ends of the preform and cable are received in a metal shell where connections are made to the signal conductors of the cable. The forward face of the preform flange presses against rearward end of the shell that carries an O-ring, and a cap threaded onto the shell presses against the rearward face of the flange to hold it securely against the rearward end of the shell. The forward ends of the preform and cable sheath are prevented from hosing in under high undersea pressure by a position fixing member of rigid insulative material that abuts the extreme forward end of the sheath and the forward end of the preform, the position-fixing member being supported against forward axial movement by a ledge formed on the shell.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention will best be understood from the following description when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional side view of anunderwater connector assembly constructed in accordance with-the in vention;

FIG. 2 is a view taken on the line 2'2 of FIG. 1;

FIG. 3 is a perspective view of the connector of FIG. 1, showing it assembled to another connector for splicing two underwater cables;

FIG. 4 is a perspective view of the cable'end and preform of the connector assembly of FIG. 1, showing the manner in which the preform is joined to the cable;

FIG. 5 is a sectional side view of the cable'end and preform of F IG. 4 showingthe manner inwhichthe position fixing and potting memberv is formed therein; and

FIG 6 is a sectional view of a' connector assembly constructed in accordance with another embodiment of the invention, for a coaxial cable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates an underwater connection assembly 10 for splicing the end of an underwater cable l2'to' the end of another length of underwater cable. The connection assembly 10 includes a preform 14 mounted on the end portion 12E of the cable for holding the cable securely in a connector shell 16, and three socket contacts 18 for connection to three wires 20, 22. and 24 of the cable. The connector assembly 10 is designed to be connected to another similar connector assembly 26 which has plugs that fit into the sockets 18. Both of the connector assemblies 10, 26 are designed so that they can be readily attached in the field, on a maintenance vessel or the like, and to provide an assembly that reli ably resists leakage or other degradation over a long period of time even when subjected to the extremely high pressures that exist at great ocean depths.

The cable 12 includes a sheath 28 of a flexible thermoplastic material such as polyethylene, which resists degradation in the underwater environment over long periods of time. The preform 14 is constructed of the same thermoplastic material as the cable sheath. The preform is of tubular shape and has a long rearward portion 30 which surrounds the cable sheath 28 and which is heat sealed thereto so that the inner wall of the preform merges with the outer wall of the cable sheath. The preform 14 has a forward end portion 32 which fits within the connector shell 16 and which extends to a position even with the extreme forward end or tip 28T of the cable sheath. An outwardly extending flange 34 formed on the preform near its forward end abuts the rearward end 16R of the connector shell. A cap 36 has an end wall 38 which bears against the rearward face 34R of the preform flange to press the forward face 34F of the preform tightly against the connector shell. The cap has a hole 40 through which the preform extends, and has an internally threaded tubular portion 42 which is threaded onto the rearward end portion of the shell 16. Further sealing of the shell is provided by O-rings 44, 46 mounted in grooves in he connector shell. The O-rings engage the forward face of the flange 34 and the front portion 32 of the preform which is received in the shell.

The forward ends of the wires 20-24, and of a braided shield 48 ofth cable that extends beyond the cable sheath 28, project through a position fixing memher 50. The member 50 is constructed of a hard insulative material, such as an epoxy compound, and is potted around the wires and braided shield 48. The member 50 also abuts the extreme forward ends of the preform and cable at 32T and 28T. The forward end of the position fixing member 50 abuts an insulative holder 52 which holds the sockets 18 to which the wires are connected. The holder 62 has a ledge portion 54 which abuts a rearwardly facing ledge 56 that is formed on the inside of the shell. Accordingly, the ledge 56 on the shell supports the holder 52 against forward movement, the holder 52 supports the position-fixing member 50 against forward movement, and the member 50 supports both the preform 14 and cable sheath 28 against forward movement further into the connector shell 16.

The assembly also includes a coupling ring 58 with a threaded forward end which can be screwed onto the other connector assembly 26 to securely hold it against the assembly 10. The complete cable splice is shown in FIG. 3, wherein the two connector assemblies 10, 26 are shown joined together to splice the cable 12 to another cable 60. In some cable systems, a repeater unit may be located between the ends of the two cables that are to be spliced, so that the connector assembly 10 would connect directly to the repeater unit.

The connection assembly 10 is designed to facilitate reliable construction in the field, as where a maintenance ship pulls up a damaged cable and must remove the damaged. section and splice the cable ends. A repairman first strips away the cable sheath 28 from the end of the cable and strips away part of the braided shield 48. He must then attach the preform 14 to the forward end portion 12E of the cable about the sheath thereof. This is accomplished in the manner shown in FIG. 4, with the aid of an attaching apparatus 70. The attaching apparatus 70 includes a pair of

dies

72, 74 with

recesses

76, 78 that match the preform. The dies have heating elements that are energized by current applied through cords 80, 82. A workman first slips the cap 36 onto the cable 12 and then inserts the forward end 12E of the cable into the preform 14 so that the extreme front ends of the cable sheath and preform are even with one another. He then places the preform 14 with the cable therein in the attaching apparatus 70 as illustrated, and closes the dies 72, 74 and locks them together with a toggle lock 84. The dies are heated to a fusion temperature at which the polyethylene material of the preform and cable sheath become softened and can merge into one another. After a sufficient period of time, the dies are opened and the cable and preform assembly is removed. The wires -24 of the cable are then attached to the sockets l8 and the sockets are mounted in the holder 52. The assembly is then placed in a cylindrical mold 86, as shown in FIG. 5, of the same diameter as the forward end 32 of the preform and the rearward end of the holder 52. An epoxy compound is then poured into the mold to form the position-fixing member 50. The apparatus is then inserted into the connector shell 16, and the cap 36 is screwed into place to complete the connector assembly 10.

The connector assembly 10 can be constructed in the field, and yet provide high reliability against leakage under the high water pressure existing at deep ocean depths. The provision of a reliable connection at such an environment requires that a strong and reliable waterproof seal be provided between the preform l4 and the cable sheath 28, and between the preform and the connector shell 16. The lont tubular portion 30 of the preform is bonded to the cable sheath all along their adjacent areas by the combination of heat that softens the preform and pressure that forces the preform portion 30 uniformly into contact with the cable sheath. In addition, the fact that the preform and sheath are constructed of the same thermoplastic material means that at the softening temperature of the preform, the sheath is also softened and the preform and sheath merge into each other to form a large unitary member.

Sealing of the preform flange 34 to the connector shell 16 is largely accomplished by deformation of the thermoplastic material of the flange 34 against the rear end 16R of the shell. The O-rings 44, and 46 serve to provide additional protection against leakage.

The high pressure existing at great ocean depths could cause damage by forcing the cable 12 and/or the preform 14 further into the shell 16, this movement often being referred to as hosing in. The hard position fixing member 50 which abuts the extreme forward ends 28T and 32T of the cable sheath and preform prevents such movement. The fact that the same member 50 abuts both the cable sheath and preform means that it prevents relative axial movement of the sheath with respect to the preform, to prevent separation of the preform from the sheath along their cylindrical areas of contact.

FIG. 6 illustrates another connector assembly which forms a connection with a cable 92 of the coaxial type that has a pair of coaxial conductors 94, 96"that are enclosed in a sheath 98. The assembly includes a preform 100 that is heat-bonded to the cable sheath and which is of the same thermoplastic material as the cable sheath. The preform has a flange 102 near its forward end, and a front portion 104 in front of the flange. The front portion 104 has a groove 104g at the forward end which extends to a depth at 104T which is even with the extreme front end or tip 98T of the cable sheath. The preform front end also has a lip portion 104L that extends beyond the cable sheath. A hard insulative position fixing member 106 received within the preform lop 104L and closely centered by the preform lip, abuts the adjacent tips or ends 98T and 104T of the cable sheath and preform. The forward end of the position-fixing member 106 abuts a holding member 108, which may be constructed of a molded epoxy, and which is mounted within a connector shell 110 to prevent forward movement therealong. The forward end portion 104 of the preform and the rearward end of the position-fixing member 106 are both held within a sealing base 111 of rigid material, which may be a conductive material such as a metal. The sealing base 111 fits within the rearward end of the shell 110 and is sealed thereto by O-rings 112. A cap 114 threaded onto the rearward end of the shell forces the preform flange 102 against the rearward end of the sealing base 111. The preform flange can deform to provide a watertight fit against the sealing base, and in addition an O-ring 116 is provided to form an even more secure watertight seal.

As in the case of the connector assembly of FIG. 1, the forward end of the assembly is constructed to permit joining to another similar connector assembly. To accomplish this, the connector assembly 90 is provided with a plug apparatus 120 which connects to the coaxial conductors of the cable 92 and which forms a plug that can be received into a corresponding socket on the other connector assembly.

The connector assembly 90 is assembled by slipping the preform 100 over the cable sheath 98 and placing them in a heat and pressure applying apparatus similar to the attaching apparatus 70 of FIG. 4. A potting apparatus of the type illustrated in FIG. 5 is not required, because the position-fixing member 106 is a factorymanufactured article. The shell 110 is also supplied with the holder 108 and plug apparatus 120 in place. It is only necessary to slip the sealing base 111 onto the preform, insert the position-fixing member, attach a braid clamp 122 and socket contact 124 and solder them in place on the coaxial conductors, and insert the assembly into the shell. The assembly is completed by screwing the cap 114 onto the shell.

Thus, the invention provides an underwater connector apparatus and construction method which permits the construction of a reliable underwater connection assembly in the field. This is accomplished by utilizing a cable with a thermoplastic sheath and a preform of the same thermoplastic material, and by bonding them together with heat and pressure so that the two members merge into one another along a large surface area. The preform is constructed with an outwardly extending flange that permits sealing to a connector shell or a sealing base within the shell. Axial movement or hosing in" of the cable sheath with respect to the shell or with respect to the preform is prevented by utilizing a position fixing member that abuts the extreme forward end of the cable sheath and a forwardly facing surface on the preform. The underwater connection is useful for a variety of cables, including those which have conductors that carry light or current signals or power.

Although particular embodiments of the invention have been described and illustrated herein, it is recongized that modifications and variations may readily occur to those skilled in the art and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

What is claimed is: l. A method for making a connection to the end of an undersea cable which has a plastic sheath, comprismg:

installing a cap onto the cable; installing on the cable sheath, a tubular preform of the same plastic material as the cable sheath and which has an inside diameter approximately equal to the outside diameter of the cable sheath and which has a flange near one end;

placing the preform with the cable projecting therethrough, between a pair of dies;

heating the dies to approximately the fusion temperature of said plastic material of said cable and preform; pressing the heated dies against the preform to squeeze the preform onto the cable sheath; removing the preform and cable from between the dies and inserting the preform and cable into a shell; and

installing the cap onto the shell and against the flange of the preform.

2. The method in claim 1 wherein:

said cable includes conductors surrounded by the sheath of the cable; and including trimming the sheath from around the cable end and molding insulative potting material that becomes hard when solid, around the conductors of the cable and up to the front end of the sheath and preform, said potting material being formed with an outside dimension small enough to fit into said shell; and

installing a fixing means in said shell which can securely prevent forward movement of material; and wherein said step of inserting the preform and cable into the shell includes inserting the molded potting material into the shell and agains the fixing means so that it can securely prevent any further forward movement of potting material into the shell under high undersea pressures.

3. An underwater cable connection comprising:

a cable having a conductor and an outer flexible sheath surrounding the conductor, said cable having a forward end portion with the conductor extending beyond the sheath at said end portion;

a tubular preform closely surrounding said cable end portion and joined along its internal surface to the outside of the sheath of the cable;

a shell surrounding the'ends of said cable and preform, said shell having a rearwardly facing internal surface; and

position fixing means of hard insulative material with a hole through which said conductor extends, said position fixing means abutting the rearwardly facing internal surface of the shell and also aubtting the extreme forward end of said cable sheath and a forward end surface of the preform to prevent forward end movement of the cable sheath and preform, whereby to prevent hosing in" of the cable or relative axial movement of the preform with respect to the cable under high water pressures.

4. The apparatus described in claim 3 wherein:

said cable is a coaxial cable with a pair of coaxial conductors, a first of the conductors being an electrically conductive tube and a second of the conductors being an electrically conductive wire extending along the center of the tube;

said preform has a front end extending beyond the cable sheath and having a groove at the front end that extends to a depth even with the sheath; and

said position fixing means includes a member which has a tubular rear end portion extending into said groove at the front end of the preform and abutting the preform at the bottom of the groove and the extreme end of the cable sheath.

5. The apparatus described in claim 3 wherein:

said cable has a plurality of flexible wires that can move towards and away from each other; and

said position fixing means includes an insulative potting material extending about the wires and potting them in place and extending to and molded against the front ends of the cable sheath and preform.

6. The apparatus described in claim 3 wherein:

said shell has external threads on its rearward end and a rearwardly-facing groove on its rear end with an O-ring seal therein; and

said preform has an outwardly extending flange near its front end, said flange being of larger diameter than the O-ring and abutting the O-ring; and including V a cap having a rear end wall against the rear face of the preform flange, the end wall including a hole through which the preform extends, and the cap having a tubular threaded front portion threaded onto said shell so that the rear wall of the cap presses the preform flange against the O-ring.

7. The apparatus described in claim 3 wherein:

said shell has external threads on its rearward end and has a cylindrical rear internal surface at the rear end with a rearwardly facing internal ledge at the forward end of the rear cylindrical internal surface;

said preform has an outwardly-extending flange near its front end; and including a sealing base of hard material with an outer diameter slightly smaller than the diameter of said rear cylindrical internal surface of the shell and disposed therein, said sealing base having a forward end disposed against the rearwardly facing internal ledge of the shell, said sealing base having an O-ring along its outer surface and sealed against the cylindrical rear internal surface of the shell, and said sealing base having a rearwardly facing rear end with an O-ring groove therein holding an O-ring and abutting the front face of the preform flange; and

a cap having a rear end wall against the rear face of the preform flange, the rear end wall of the cap including a hole through which the preform extends, and the cap having a tubular threaded front portion threaded onto said shell so that the rear wall of the cap presses the preform flange against the rear end of the sealing base.

8. An underwater cable connection comprising:

a cable having a conductor and an outer sheath of a thermoplastic material surrounding the conductor, said cable having a forward end portion;

a tubular preform constructed of thermoplastic material and closely surrounding the forward end portion of the sheath, and with the inner surface of the preform merging into the outer surface of the cable sheath, said tubular preform having an outwardlyextending flange, and the radially inner wall of the preform extending even with the extreme front end of the cable sheath;

a shell assembly receiving the forward ends .of the cable and preform and sealed to the flange of the preform; and

position fixing means mounted in said shell to prevent forward movement therein and abutting both the extreme front end of the sheath and the preform portion thereabout.

Claims

1. A method for making a connection to the end of an undersea cable which has a plastic sheath, comprising: installing a cap onto the cable; installing on the cable sheath, a tubular preform of the same plastic material as the cable sheath and which has an inside diameter approximately equal to the outside diameter of the cable sheath and which has a flange near one end; placing the preform with the cable projecting therethrough, between a pair of dies; heating the dies to approximately the fusion temperature of said plastic material of said cable and preform; pressing the heated dies against the preform to squeeze the preform onto the cable sheath; removing the preform and cable from between the dies and inserting the preform and cable into a shell; and installing the cap onto the shell and against the flange of the preform.

2. The method in claim 1 wherein: said cable includes conductors surrounded by the sheath of the cable; and including trimming the sheath from around the cable end and molding insulative potting material that becomes hard when solid, around the conductors of the cable and up to the front end of the sheath and preform, said potting material being formed with an outside dimension small enough to fit into said shell; and installing a fixing means in said shell which can securely prevent forward movement of material; and wherein said step of inserting the preform and cable into the shell includes inserting the molded potting material into the shell and agains the fixing means so that it can securely prevent any further forward movement of potting material into the shell under high undersea pressures.

3. An underwater cable connection comprising: a cable having a conductor and an outer flexible sheath surrounding the conductor, said cable having a forward end portion with the conductor extending beyond the sheath at said end portion; a tubular preform closely surrounding said cable end portion and joined along its internal surface to the outside of the sheath of the cable; a shell surrounding the ends of said cable and preform, said shell having a rearwardly facing internal surface; and position fixing means of hard insulative material with a hole through which said conductor extends, said position fixing means abutting the rearwardly facing internal surface of the shell and also aubtting the extreme forward end of said cable sheath and a forward end surface of the preform to prevent forward end movement of the cable sheath and preform, whereby to prevenT ''''hosing in'''' of the cable or relative axial movement of the preform with respect to the cable under high water pressures.

4. The apparatus described in claim 3 wherein: said cable is a coaxial cable with a pair of coaxial conductors, a first of the conductors being an electrically conductive tube and a second of the conductors being an electrically conductive wire extending along the center of the tube; said preform has a front end extending beyond the cable sheath and having a groove at the front end that extends to a depth even with the sheath; and said position fixing means includes a member which has a tubular rear end portion extending into said groove at the front end of the preform and abutting the preform at the bottom of the groove and the extreme end of the cable sheath.

5. The apparatus described in claim 3 wherein: said cable has a plurality of flexible wires that can move towards and away from each other; and said position fixing means includes an insulative potting material extending about the wires and potting them in place and extending to and molded against the front ends of the cable sheath and preform.

6. The apparatus described in claim 3 wherein: said shell has external threads on its rearward end and a rearwardly-facing groove on its rear end with an O-ring seal therein; and said preform has an outwardly extending flange near its front end, said flange being of larger diameter than the O-ring and abutting the O-ring; and including a cap having a rear end wall against the rear face of the preform flange, the end wall including a hole through which the preform extends, and the cap having a tubular threaded front portion threaded onto said shell so that the rear wall of the cap presses the preform flange against the O-ring.

7. The apparatus described in claim 3 wherein: said shell has external threads on its rearward end and has a cylindrical rear internal surface at the rear end with a rearwardly facing internal ledge at the forward end of the rear cylindrical internal surface; said preform has an outwardly-extending flange near its front end; and including a sealing base of hard material with an outer diameter slightly smaller than the diameter of said rear cylindrical internal surface of the shell and disposed therein, said sealing base having a forward end disposed against the rearwardly facing internal ledge of the shell, said sealing base having an O-ring along its outer surface and sealed against the cylindrical rear internal surface of the shell, and said sealing base having a rearwardly facing rear end with an O-ring groove therein holding an O-ring and abutting the front face of the preform flange; and a cap having a rear end wall against the rear face of the preform flange, the rear end wall of the cap including a hole through which the preform extends, and the cap having a tubular threaded front portion threaded onto said shell so that the rear wall of the cap presses the preform flange against the rear end of the sealing base.

8. An underwater cable connection comprising: a cable having a conductor and an outer sheath of a thermoplastic material surrounding the conductor, said cable having a forward end portion; a tubular preform constructed of thermoplastic material and closely surrounding the forward end portion of the sheath, and with the inner surface of the preform merging into the outer surface of the cable sheath, said tubular preform having an outwardly-extending flange, and the radially inner wall of the preform extending even with the extreme front end of the cable sheath; a shell assembly receiving the forward ends of the cable and preform and sealed to the flange of the preform; and position fixing means mounted in said shell to prevent forward movement therein and abutting both the extreme front end of the sheath and the preform portion thereabout.