CN1961237A - Mechanically separable cable - Google Patents

Abstract

A cable (1), comprising a core (2) for guiding at least one transfer element (4) and a sheath (3) surrounding the cable core, used to protect the transfer element, provided with at least two weak points (11-14) which are distributed in the direction of the periphery of the cable (1), extending in a longitudinal direction of said cable, and which are disposed inside the cable sheath (3). One surface (15), which is made of cable sheath material (3) adjacent to a corresponding weak point and is oriented such that it faces the respective weak point (11-14), is respectively provided inside the cable sheath (3). The cable sheath material (3) on the side of the respective surface (15) facing the weak point (11-14) is not joined to or approximately not joined to the remaining cable sheath material. The weak points (11-14) are disposed in such a way that a cable sheath segment (6) can be detached at said weak points when the cable sheath is separated. The cable sheath (3) can thus be removed in a comparatively simple manner without occurring any substantial damage to the remaining components of the cable.

Description

mechanically detachable cable

technical field

The invention relates to a mechanically detachable cable having a cable core for guiding at least one transmission element and a cable sheath surrounding the cable core for protecting the transmission element.

Background technique

In order to substantially protect the transmission elements of cables for transmitting optical or electrical signals, eg for transmitting data, video or audio, from external influences, these transmission elements are usually protected by a sheath. One possible method for protecting an optical waveguide, for example in the form of a glass fiber, from external influences is to provide the optical waveguide with a coating and to apply a robust protective sleeve over the coating on the optical waveguide, the robust protection The sleeve is in the form of a cable sheath made of a suitable plastic. Communication cables are mainly sheathed with good strength and made of HDPE plastic (High Density Polyethylene).

Especially for the installation and connection of accessories, etc., it is necessary to open the cable sheath of the cable and remove it from the optical waveguide. Since the cable sheathing, for example in the form of an HDPE cable sheath, can only be removed again with difficulty, this makes the installation and connection technology for these cables more difficult. The opening of these cables is time-consuming and it is often not possible to exclude damage to the cables and/or to the transmission elements. Even at the cable ends remote from the cable (mid span access), users often require good accessibility to the transmission elements. The cable jacket must be removed over a considerable area without cutting the cable. This is particularly difficult, especially in the case of cables with so-called center conductors, where tension elements are located in the region of the outer sheath to absorb tension in the longitudinal direction of the cable. In this case, in addition to the movement of the cable sheath, the tension element must also be removed in order to gain access to the central guide tube of the central conductor in which the transmission element is located.

Hitherto, in order to remove the cable jacket from the cable, it has been common practice to include so-called rip threads or similar high tension, elongated elements in the cable jacket. High tension elements such as these by themselves have no other function than to define an operating point on the cable sheath at which point the cable sheath can be severed by applying tension to the high tension element. The tear wire is usually embedded in the cable sheath, thus enabling the cable sheath to be mechanically severed.

Contents of the invention

The invention is based on the object of providing a mechanically severable cable in which the cable sheath can be removed relatively easily with as little damage as possible to other cable elements.

Another object of the invention is to specify a method for manufacturing a cable such as this.

This object is achieved by a cable according to patent claim 1 and by a method according to patent claim 19 .

The cable according to the invention has a cable core for guiding at least one transmission element and has a cable sheath surrounding the cable core for protecting the transmission element; At least two weak locations extending and disposed within the cable sheath. A surface facing the respective weakening and consisting of cable sheathing material adjacent to the respective weakening is provided in each case in the cable sheathing, the cable sheathing material not being in contact with or Substantially no engagement with remaining cable jacket material on the respective surface side facing the weakened portion. The weakened portion is provided in such a way that when the cable sheath is cut at said weakened portion, the cable sheath section can be removed.

The arrangement of the weakened portion in the cable sheath makes it possible to cut the cable sheath or a section from the cable sheath, for example in the form of a circular segment, in a very simple manner and substantially for other No damage will occur to the cable elements. The weakening may be arranged such that the sections of the cable sheath can be cut with a suitable tool or even without the aid of any tool. Preferably during the manufacture of the cable a weakening is created in the longitudinal direction of the cable. These weakenings are arranged in the cable sheath such that the cable sheath sections can be removed, the cable sheath can be removed so that the cable core can be reached.

In order to manufacture such a cable, the cable sheath is pressed, the weakening is preferably incorporated into the pressing or during the pressing of the cable sheath.

The at least one weakening is preferably formed by a groove, in particular a groove having a V-shaped configuration in the radial direction of the cable. A V-shaped weakening such as this preferably penetrates about 10% to 20% of the cable sheath in the radial direction of the cable.

In one embodiment, at least one weakened portion is in the form of a slit in the radial direction of the cable. A weakening such as this in the form of a slit may open towards the outside of the cable sheath in the radial direction of the cable. On the other hand, a weakening such as this in the form of a slit can open towards the inside of the cable sheath in the radial direction of the cable. The advantage of the first embodiment of the weakened portion in the form of a slit is that the weakened portion is easily accessible from the outside and can be well recognized. An advantage of the second embodiment is that this enables the cable sheath to have a smooth outer surface. The unfilled weak point in the form of a slit in the second embodiment cannot be reached from the outside and therefore cannot become soiled or damaged.

The width of a weakening such as this, in the circumferential direction of the cable, is preferably approximately less than 1 mm, in particular between 250 μm and 500 μm. This width corresponds to current manufacturing capabilities, especially if the cable jacket is pressed, the weakening being added during the pressing of the cable jacket. Having a weakening such as this size does not significantly reduce the strength of the cable jacket. A weakening such as this preferably penetrates about 80% of the cable sheath in the radial direction of the cable.

In one embodiment at least one weak point is not filled such that eg an open groove or open slot is formed in the cable sheath. An open weakness such as this is easily accessible so that a tool can conveniently engage the weakness to sever the cable sheath.

In another embodiment, at least one weakened portion is in the form of a separation layer extending in the radial direction of the cable. A separation layer such as this is for example of a different material than the remaining material of the cable jacket. The material used for the separation layer preferably has a separation effect between the weakened portion and the opposing surface of the main cable jacket material. In the case of cable sheaths made of MDPE (medium density polyethylene), suitable materials for this purpose are in particular: polyamide, polybutylene terephthalate (PBT), polycarbonate or other A material whose melting point is substantially different from the melting point of the main cable jacket material.

According to a preferred embodiment of the cable, at least one tension element or support element is arranged in the cable sheath. These tension elements or bearing elements are especially required in order to stabilize the cable longitudinally against tension or thrust. Tension elements are thus designed to resist pulling forces and comprise, by way of example, high tension threads such as aramid threads. Instead, the support element has eg glass-fibre-reinforced plastic for high strength. According to the invention, at least one of the weakenings in the cable sheath is now arranged in the circumferential direction of the cable in such a way that in the radial direction of the cable the weakening substantially coincides with the tension element or bearing element. The radial direction of the weakened portion and the tension element or support element may be the same, in which case the weakened portion may be located above or below the tension element or support element in the same radial direction. If the weakened portion is located above the tension element or support element, it is advantageous for the weakened portion to be used to help guide a tool, eg for cutting the cable sheath. This makes it possible to avoid damage to the cable core, since the tension element or support element is cut first. When a tension member or support member such as this is exposed, it can be used to further tear apart the cable jacket. Tension or support elements may be combined with any of the embodiments of weakening already mentioned, including: internally located, externally located, V-shaped or slot-shaped, filled with a separation layer, or not covered. filling.

According to another preferred embodiment of the cable according to the invention, the cable has a conductor in the cable sheath with a conductor sleeve in which the transmission element is arranged. The conductor is, for example, an optical fiber group comprising a plurality of optical fibers. According to this embodiment, at least one weakening extending in the longitudinal direction of the cable is preferably arranged in the cable bushing, by means of which the conductor bushing can be cut open. This allows the cable to be fully opened, as both the cable sheath and the inner conductor can easily be removed through the respective weakened portions.

The weakening in the conductor sleeve is preferably arranged in the circumferential direction of the cable in such a way that the weakening substantially coincides with a weakening in the cable sheath in the radial direction of the cable. The position of the weakening in the cable sheath thus matches the position of the corresponding weakening in the conductor. This enables the cable sheath and the conductor sleeve to be removed in one operation in an easily accessible manner and, moreover, enables access to the "correct" conductor section once the cable sheath has been opened. For this purpose, the cable sheath and the conductor sleeve are preferably produced in the same process. For example, the weakening in the conductor sleeve is produced by a tool entering the conductor sleeve while passing through an extruder for producing the cable sheath. For example, when passing through an extruder, the center tube is slotted in such a way with appropriate tooling that the weakened portion is simultaneously incorporated into the cable sheath.

In the following the invention will be described in more detail with reference to the accompanying drawings which depict a preferred embodiment of the cable according to the invention.

Description of drawings

Figure 1 shows a schematic cross-section through a cable sheath of a typical embodiment of a cable according to the invention, cut at various points,

Figure 2 shows a cross-sectional view of a cable of a different embodiment with a weakened portion arranged in the cable sheath,

Figure 3 shows a cross-sectional view of another embodiment of a cable with a weakened portion arranged in the cable jacket, and

Fig. 4 shows a cross-sectional view of a cable with a weakened portion in both cases arranged in the cable sheath and in the center conductor.

Detailed ways

Figure 1 shows a schematic cross-section through a cable jacket of a typical embodiment of a cable cut at various points. The cable 1 comprises a cable core 2 in the form of a central conductor set to guide a transmission element 4 in the form of an optical fiber. The cable sheath 3 surrounds the cable core 2 and serves to protect the optical fiber 4 and the central conductor 2 . A plurality of weakened portions 11 are provided, distributed in the circumferential direction of the cable 1 along the longitudinal direction of the cable, and arranged in the cable sheath 3 . The weakened portion 11 is arranged in such a way that the cable sheath segment 6 can be removed by cutting the cable sheath 3 at the weakened portion. The weakened portion 11 is shown in FIG. 1 as a usual opening, which has been cut open. When at least two weakened portions 11 are severed, the central cable sheathing element, indicated for example at 6, can be removed.

Figure 2A shows a cross-sectional view of a cable including a different embodiment of a weakened portion disposed in the cable jacket. According to this embodiment of the cable, the cable 1 has a central conductor in a cable sheath 3 equipped with a cable sleeve 2 in which an optical fiber 4 is arranged. The central conductor itself has a central support element 5 . The support element 7 is arranged in the cable sheath 3 . These support elements are especially needed in order to stabilize the cable against thrust or side forces. The support element 7 has, for example, glass-fiber-optic-reinforced plastic for high rigidity.

In the example shown in FIG. 2A , the weakened portions 12 and 13 are slot-shaped in the radial direction of the cable 1 . The weakened portion 12 is open towards the outer side 31 of the cable sheath 3 in the radial direction of the cable. Instead, the weakened portion 13 is open towards the inner side 32 of the cable sheath 3 in the radial direction of the cable. The embodiment of the weakened portion 12 has the advantage that it is easily accessible from the outside and can be easily identified. The embodiment of the weakened portion 13 has the advantage that the cable sheath 3 has a smooth surface.

In the circumferential direction of the cable 1 , the width of the weakened portions 12 and 13 is less than about 1 mm, in particular a width between 250 μm and 500 μm. Weaknesses 12 and 13 having such dimensions do not significantly reduce the strength of the cable sheath 3 . Weaknesses 12 and 13 preferably pass through approximately 80% of the cable sheath 3 in the radial direction of the cable. In this case, the sheathing material 3 is reduced by 80% at the weak point, leaving 20% of this sheathing material.

FIG. 2B shows a detailed view of the cable shown in FIG. 2A , in particular an enlarged view of the weakened portion 12 arranged in the cable sheath 3 . The figure shown and the principles explained with reference to it can be applied in a corresponding manner to the weakened portion 13 (and also to the weakened portions 14 and 20 also shown in the subsequent figures). The surfaces 15 a , 15 b , 15 c of the cable jacket material 3 facing the weakened portion 12 adjacent to the weakened portion are formed by the weakened portion 12 in the cable jacket 3 . Cable jackets are primarily made of one material. In this case, the main cable jacket material 3 is not bonded, or substantially not bonded, to this (same) cable jacket on the side of the surface 15a, 15b, 15c facing the weakened portion 12 the remainder of the material. This means that the cable jacket 3 can be cut more easily at this point because the cable jacket material can be cut more easily at this point due to lack of any joint or due to a bad joint. However, the weakened portion 12 has dimensions such that the strength of the cable sheath 3 is not significantly weakened.

Weaknesses 12 , 13 may be unfilled, creating open slots in the cable jacket 3 . An open weakness such as this is easily accessible so that a tool can easily engage the weakness to sever the cable sheath.

At least one or all of the weaknesses in the cable jacket may be filled with a material that is used as a separation layer and that is different from the other main cable jacket material.

In another embodiment, the weakened portion 12 shown on the left is formed with a separation layer and extends in the radial direction of the cable. This separating layer 12 has a material 16 different from the main cable sheathing 3 , in particular a material that produces a separating effect due to the lack of or poor adhesion between the weakened portion 12 and the opposite side of the main cable sheathing material 3 . The separation point 13 is also optionally filled with a separation material 16, or as shown is left unfilled. In case the cable jacket is mainly made of MDPE (medium density polyethylene), suitable materials for this purpose are, inter alia, polyamide, polybutylene terephthalate (PBT), polycarbonate Esters or materials whose melting point differs significantly from the melting point of the cable jacket material. All weakenings in the cable jacket are preferably formed with the same embodiment and all have a separation layer such as this, or some have a separation layer such as this and others have a separation layer such as this Does not have any such separation layer. In Fig. 2A, both weakened portions 12 are filled with a material 16 which may be formed from one of the materials described above.

Figure 3 shows a cross-section through a cable of another embodiment with a weakened portion arranged in the cable jacket. The weak portion 14 is in the shape of a groove with a V-shaped structure along the radial direction of the cable. The groove 14 penetrates approximately 10% to 20% of the cable sheath in the radial direction of the cable. Furthermore, tension elements 8 and support elements 7 are arranged in the cable sheath 3 . The grooves 14 are arranged in the circumferential direction of the cable 1 in such a way that the grooves 14 substantially coincide with the tension elements 8 in the radial direction of the cable. In this case, viewed radially, one of the grooves 14 is arranged above one of the tension elements 8 in the cable sleeve. Alternatively, an arrangement can also be used in which the groove 14 coincides with the support element 7 in the radial direction of the cable. Seen in the radial direction, these grooves can be arranged above one of the support elements 7 (not shown). This type of interrelationship arrangement is such that when the cable sheath 3 is severed at the groove 14, the sheath is first cut on the tension element 8 or support element 7 so that damage to the cable core can be prevented. When such a tension element 8 or a support element 7 is exposed, it can be used to further tear the cable sheath 3 apart.

FIG. 4 shows a cross section through the cable 1 , wherein the respective weakenings 13 and 20 extending in the longitudinal direction of the cable are arranged not only in the cable sheath 3 but also in the conductor sleeve 2 of the central conductor. . In this case, the weakened portion 20 is in the form of a slot or groove open on the outside, and its design and operating principle correspond to the design and operating principle of the weakened portions 12 to 14 in the cable sheath 3 of the previous embodiment. operating principle. This enables the cable 1 to be left open in its entirety, since both the cable sheath 3 and the inner conductor sleeve 2 can easily be removed through the respective weakened portion 13 , 20 .

The weakening can be created simultaneously with the pressing of the cable sheath. The slits can be added during or simultaneously with the pressing of the sheath. Suitable tools are provided for this purpose in the extruder head to incorporate the weakening into the sheath. The sheathing material 3 can likewise be extruded together with the separating material 16 . In the modification shown in Figure 4, when passing through the extruder head, the center tube 2 is slit in the same process using suitable tools and the weakened portion 13 is simultaneously incorporated into the sheath using suitable tools, or The poorly viscous separation layer material is pressed at the same time as the sheath material 3 is pressed.

The weakened portion 20 in the conductor sleeve 2 is preferably arranged in the circumferential direction of the cable 1 in such a way that in each case the weakened portion 20 meets the weakened portion 13 in the cable sheath 3 in the radial direction of the cable. One is basically the same. The position of the weakening 13 in the cable sheath 3 thus matches the position of the corresponding weakening 20 in the conductor bushing 2 . This enables the cable sheath 3 and the conductor sleeve 2 to be removed in one operation in an easily accessible manner, while also providing access to the conductor section concerned by the operator once the cable sheath 3 has been opened .

Claims (22)

1. A cable (1) comprising: a cable core (2) for guiding at least one transmission element (4), and a cable sheath (3) surrounding the cable core for protecting the transmission element, the cable sheath comprising a main material, at least two weakened portions (11-14) distributed in the circumferential direction of the cable (1), extending in the longitudinal direction of the cable and arranged in the cable sheath (3), The surface (15) of the main cable sheathing material (3) facing each weakening (11-14) adjacent to the respective weakening, which in each case is arranged in the cable sheathing ( 3), the engagement of the main cable sheathing material (3) with the remainder of the main cable sheathing material on the side of each surface (15) facing the weakened portion (11-14) is reduced, and The weakened portions (11-14) are arranged relative to each other such that when the cable sheath (3) is cut at the weakened portion, the cable sheath segments (6) can be separated. 2. The cable of claim 1, Wherein, at least one of the weakened parts (14) is formed by a groove, which especially has a V-shaped structure along the radial direction of the cable (1). 3. The cable of claim 2, Wherein, the at least one weak portion (14) passes through about 10%-20% of the cable sheath (3) along the radial direction of the cable. 4. A cable as claimed in any one of claims 1-3, At least one of the weakened parts (12, 13) is in the shape of a slit in the radial direction of the cable. 5. The cable of claim 4, Wherein, the at least one weak portion (12) is open towards the outer side (31) of the cable sheath (3) along the radial direction of the cable (1). 6. The cable of claim 4, Wherein, the at least one weak portion (13) is open towards the inner side (32) of the cable sheath (3) along the radial direction of the cable (1). 7. A cable as claimed in any one of claims 4-6, Therein, at least one of the weakened portions (12, 13) has a width in the circumferential direction of the cable (1) of approximately less than 1 mm, in particular between 250 μm and 500 μm. 8. A cable as claimed in any one of claims 4-7, Wherein, the at least one weak portion (12, 13) penetrates about 80% of the cable sheath (3) in the radial direction of the cable (1). 9. A cable as claimed in any one of claims 1-8, Wherein, at least one of the weakened portions (11-14) is not filled with the main cable jacket material. 10. A cable according to any one of claims 1-8, Wherein at least one of the weakened portions (11-14) is in the form of a separation layer extending radially of the cable (1) and having a material different from the main cable sheath material. 11. A cable as claimed in any one of claims 1-10, Wherein at least one of the weakened portions (11-14) has a material (16) different from the main cable jacket material (3). 12. A cable as claimed in any one of claims 1-11, Wherein at least one of the weakened portions (11-14) is filled with a material (16) causing a separation effect between the weakened portion (11-14) and the opposing surface of the main cable jacket material (3). 13. A cable as claimed in claim 11 or 12, Wherein, the at least one weak portion (11-14) is filled with at least one of polyamide, polybutylene terephthalate (PBT) or polycarbonate, or has a melting point different from that of the main cable sheath. Set material (3) to the melting point of the material. 14. The cable of any one of claims 1-13, wherein: At least one tension element or support element (8, 7) is arranged in the cable sheath (3); At least one of the weakened portions (14) in the cable sheath (3) is arranged along the circumference of the cable (1) in such a way that the weakened portion is located in relation to the tension element or support element (8, 7) Basically the same cable radial up. 15. The cable of claim 14, wherein: The cable (1) has a conductor in the cable sheath (3) with a conductor sleeve (2) in which the transmission element (4) is arranged; The tension or support elements (8, 7) are arranged in the radial direction of the cable (1) between the at least one weakness (14) in the cable sheath and the conductor sleeve (2). 16. The cable of any one of claims 1-15, wherein: The cable (1) has a conductor in the cable sheath (3) with a conductor sleeve (2) in which the transmission element (4) is arranged; At least one weakening (20) extending in the longitudinal direction of the cable is arranged in the conductor sleeve (2), through which weakening (20) the conductor sleeve (2) can be cut. 17. The cable of claim 16, Wherein, the weakened part (20) in the conductor sleeve (2) is arranged along the circumferential direction of the cable in such a way that its radial direction is substantially the same as a weakened part in the cable sheath (3) The radial direction of the portion (13) is consistent. 18. A cable as claimed in any one of claims 1-17, Therein, the transmission element (4) is in the form of an optical waveguide. 19. A method for manufacturing a cable as claimed in any one of claims 1-18, wherein the cable sheath (3) is pressed and the weakened portion (11-14) is pressed The cable sheathing process is added. 20. The method of claim 19, Wherein a conductor with a conductor sleeve (2) in which the transmission element (4) is arranged is arranged in the cable sheath (3), at least one weakened portion extending in the longitudinal direction of the conductor (1) ( 20) is incorporated into the conductor bushing (2). 21. The method of claim 20, Wherein, the cable sheath (3) and the conductor sleeve (2) are produced in the same operation step. 22. A method as claimed in claim 20 or 21, Therein, the weakening (20) in the conductor sleeve (2) is produced by a tool entering the conductor sleeve (2) while passing through an extruder for producing the cable sheath (3).