DE2923132A1 - A METHOD FOR MANUFACTURING A LONG DISTURBED THREAD FOR AN OPTICAL CABLE, AN OPTICAL CABLE, AND A LONG DRAWN THREAD FOR AN OPTICAL CABLE - Google Patents

Description

description

The invention relates to a thread which is used in optical cables or light guides can, on optical cables or light guides using such a thread, and on a method and a Apparatus for producing such a thread.

It has been proposed to manufacture optical cables with a central grooved element; ■ these grooves have a helical or spiral shape and accommodate dielectric optical waveguides.

The helical shape ensures that the dielectric optical waveguide is not destructive Stress and compression stress are exposed when the cable is bent. So learns a dielectric optical waveguide alternately in a bent part of a cable Compressions and tensions, so that the stresses are spread over the entire length of this curvature at least partially cancel.

Such a cable is manufactured with the following process steps: First, a grooved, with a plastic coated reinforcement or. Fastener made of metal, which forms the central thread for the cable? then the dielectric optical waveguides in the grooves placed in the central thread. The plastic is usually produced by a rotating mold extruded using a servo mechanism to get the correct ratio between angular velocity of the mold and extrusion speed

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to maintain the thread; this is the only way to increase the pitch of the helical shape over the entire length of the central thread can be kept in a predetermined range. The extrusion speed must be limited in order to avoid unfavorable shear effects that result when the plastic is rapidly directed in another direction when it is extruded in one direction. especially the The extrusion speed must be selected with great care to avoid interference or damage of the grooved structure immediately after the deformable, located at a relatively high temperature, emerges Prevent plastic from the mold.

From FR-PS 7 516 469 (Le Noane et al) a cable structure is known in which a central thread is helical Has grooves ... whose hand τ or direction of lay changes periodically along the thread. It will, however pointed out that this construction requires a very delicate manufacturing process would.

It is an object of the present invention to address the disadvantages of this known optical cable, in particular the resulting manufacturing difficulties, to avoid.

According to a first aspect of the present invention a relatively simple method for producing an elongated thread is proposed, which both for the production of normal helical threads

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as well as for making threads with reverse lay; in this process the Plastic extruded through a stationary molding tool, which is formed with a multi-fingered opening is to give the extruded plastic the grooved surface; at a remote from the molding tool Where the extruded thread is relatively rigid, the thread is twisted to give the grooves the helical shape when the extruded thread emerges from the molding tool.

According to a preferred embodiment, the plastic is twisted or twisted around a central one Extruded wire being pulled through the forming tool at a speed that is the speed the extrusion of the plastic is comparable. In particular with a thread with a reverse lay can the thread periodically at this point, first in a first direction and then in the opposite direction Direction can be twisted to modify the helical shape to a shape with periodic change in the direction of impact.

According to a second aspect of the present invention a thread for an optical cable is proposed, which has a central, stranded or twisted, Serving as a reinforcing element wire, which is surrounded by a plastic sheath, and several, in one outer surface of the envelope has formed grooves, each having the shape of a screw, each screw changing its direction of impact along the thread. In general, the reinforcement element is made of steel, while the casing is made of polyethylene is made with high density.

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In a further aspect of the present invention, an optical cable has a thread with one of the processes described above has been produced? there are dielectric, optical waveguide arranged.

According to another aspect of the present invention contains a device for producing an elongated thread for an optical cable with a thread surface, which has a plurality of helical grooves, an extrusion device with a stationary molding tool, which is designed with a multi-fingered opening, around the extruded plastic to give the grooved surface, a rotating device with an element that is used for Carrying out a rotation around the feed path for the thread is mounted, and an engaging device in the element that can grasp the thread and be driven to twist the thread to the grooves. To give helical shape when the extruded material exits the extrusion device.

A connection mechanism between the extrusion device and the twisting device can reciprocating rotation of the cylindrical element in relation to the extrusion speed of the plastic material. The position of the rotating device along the feed path for the extruded Thread is selected so that the thread is comparatively rigid at this point and for example can withstand engagement of inwardly projecting ribs on the cylindrical member in the grooves. Such ribs can have cutting edges or wheels with a sufficiently small thickness that they can be in the Grooves can be introduced.

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As an alternative to this, the thread can also be grasped by several elastic wheels which can be rotated attached to a jig; this jig itself has a center of rotation that coincides with the central axis of the thread. The elastic wheels are arranged so that they are against the thread with sufficient pressure to capture it, but the pressure is insufficient to to permanently distort the grooves.

The invention thus creates an optical cable with a grooved, central thread, which by extrusion of a Plastic has been formed over a central, stranded wire element? the grooves follow helical Tracks in which the direction of lay of the screws changes along the thread. When making the thread the plastic is extruded through a stationary mold through which the wire element is also drawn will; The thread is grasped at a certain distance behind the molding tool, viewed in the direction of flow and twisted first in one direction and then in the opposite direction, so that the screw trajectories be introduced at the point where the plastic exits the mold. Dielectric, optical Waveguides are placed in the grooves. This whole structure is then extruded from one Surrounded by plastic sheathing, which creates the finished optical cable.

The invention will be described in the following on the basis of exemplary embodiments with reference to the accompanying schematic Drawings explained in more detail. Show it

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Fig. 1 is a perspective view of a length of thread according to the present invention;

Fig. 2 shows a representation of the device for production such a thread and for inserting the dielectric optical waveguide into the grooves in the thread,

.Fig. 3 and 4 are a perspective view and a Front view of part of the device for twisting the extruded material, whereby the thread is made, and

Fig. 5 is a perspective view of the device for inserting the dielectric, optical Waveguide in the thread.

As can be seen in detail from the drawings, a thread for an optical cable has a single, central, stranded or twisted reinforcement element 1, which consists of a steel wire; A sleeve or sheath 2 made of polyethylene is placed over the reinforcing element 1 high density extruded. In the surface of the envelope there are several, in this case four the circumference spaced apart grooves 3a, 3b, 3c and 3d formed, which extend over the entire Extend the length of the thread. In using the cable, each groove takes a dielectric optical waveguide in a relatively loose frame; this entire structure is made up of an extruded plastic sheath (not shown) surround. As protection against breakage of the dielectric, optical waveguide when the optical cable bends, the grooves follow a helical path around the

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longitudinal axis of the thread (see Figure 1). However, as indicated by the reference numeral 4, the change different screw paths followed by the grooves, their hand (left to right or right to left) or direction of impact. The grooves 3 are expediently evenly distributed around the thread, so that the changes in the hand or stroke direction of the four helical paths are made at the same specific locations along the thread. So that the grooves have a generally parallel arrangement relative to one another. As can be seen from FIG. 1, the changes are made hand or lay direction at regular intervals along the thread.

In Figure 2, a device is shown schematically, the for the production of an optical cable, in which the thread described above is used. Basically this device has 3 units on, namely an extrusion unit 5, a twisting unit 6 and an insertion unit 7. During manufacture the stranded or twisted steel wire core 1 and a load of high density polyethylene 8 is introduced into the extrusion unit, which is a in detail Contains mold 9 shown in Figure 3. The polyethylene 8 is heated until it is plastically deformable is; then it is extruded around the steel wire core 1 by the molding tool 9 which is shaped so that it forms 10 grooves in the polyethylene when this the extrusion unit 5 leaves. A certain distance in the direction of movement behind the extrusion unit is the thread, which has also been cooled by a container with cooling fluid (not shown), relatively rigid; at this point the thread enters a twisting unit which twists it so that the grooves when the polyethylene emerges from the extrusion unit, the screw shape is obtained.

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In the direction of movement behind the rotating unit 6 is the insertion unit, in the dielectric optical waveguides 11 fed by coils 12 are inserted into the grooves 3.

As can be seen in detail from FIG. 3, the molten polyethylene is used to form the grooves 3 extruded through the mold 9, which has four inwardly projecting fingers 13 with straight walls. The rotating unit 6 has a mechanism with a central, cylindrical bore through which the extruded thread is drawn; the mechanism includes a gear 14 at one end that reciprocates can be turned and by a drive gear 15 is driven, which forms part of a drive chain from the extrusion unit? this drive chain is shown schematically by arrows B and C as well a drive shaft 16 indicated; the function of the drive chain is to control the oscillation speed of the Gear 14 in relation to the extrusion speed the extrusion unit 5 to set. Alternatively, the extrusion speed and drive for the twisting device can be set beforehand to the required groove characteristics without the Drive chain B and C to be obtained.

Integral with the gear 14 and in its vicinity is one Drum 16 arranged with a series of four equally circumferentially spaced slots 17, which extend through their wall. In the slots four ribs 18 are slidably mounted so that they have a limited can perform radial movement; the four

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Ribs 18 have cutting edges 19 on their inner edges with a thin cross-section protruding into the drum 16. The outer edges 20 of the ribs 18 are through a spring 21 biased radially inward.

When the rotating unit 6 is in operation, the various cutting edges 19 each come into one of the four grooves 3 in Intervention; Since the extruded plastic is relatively cold and therefore rigid at this point, the drive chain can Drive the drum 16 via the gear 14 in order to rotate the thread 2. Because the extrusion unit is not rotates, the extruded polyethylene is subjected to a shear stress between the two units 5 and 6, which leads to the fact that the grooves in the part of the polyethylene that is still very plastically deformable that is, the part exiting the extrusion unit 5 is deformed around the helical grooves to train. The change of the hand or direction of impact of the individual screws is achieved simply by that the drive direction of the drive chain is reversed.

In an alternative embodiment (not shown) the cutting edges 19 are replaced by small wheels that run in the grooves 3 in the thread 2 with slightly less friction than is the case with the blades 19.

In a further alternative embodiment (not shown) the thread is caught on its surface by three elastic wheels. These wheels are indeed on the thread with sufficient pressure so that it can be twisted by the twisting device; the However, the contact pressure is not sufficient for the grooved

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To permanently distort surface structure.

Figure 5 shows a practical embodiment of the unit 7 for inserting the dielectric optical Waveguides 11 in the grooves 3 of the thread 2. The dielectric optical waveguides are formed by four coils 12 fed, which are evenly distributed on the circumference and spaced from the web 21, along the the grooved thread 2 is pulled. The dielectric optical waveguides 11 are passed by the coils the movement of the thread itself is withdrawn, as will be explained below. The dielectric optical Waveguides 11 run through a guide with two rotatable plates 22 and 23. The thread 2 is drawn through the center of the two plates, while the dielectric optical waveguides run through openings 24 and 25, which are at uniform circumferential intervals in the plates are formed. The plate 23 is slightly thicker than the plate 22; close to openings 25 tubes 26 protrude from the downstream sides of the plate 23. The tubes 26 are closed inclined towards the axis of the thread 2; their ends 27 are flexible and pressed into the respective grooves 3, so that the dielectric optical waveguides are automatically fixed in the bases of the grooves 3, when the dielectric optical waveguides are drawn out of the tubes by pulling the thread on the Insertion unit 7 is moved past. To aid in drawing out the dielectric optical waveguides, the outlet ends of the tubes taper conically or conically, with the conical surface following radially outside is turned. In addition, the inlet ends of each tube can be formed with a mouthpiece (not shown) in order to reduce the effects of friction at the points where the dielectric optical waveguides " enter the "tubes.

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The circumferential position of the grooves at which they are engaged by the tube ends 27 regulates the angular position of the Plate 23. A drive provided with gears, which is indicated schematically by the arrow D, sets the rotation of the plate 22 in relation to the rotation of the plate 23.

In operation, the movement of the thread 2 past the tube ends 27 produces a rotation of the plate 23 which this determines how often a helical groove 3 around the longitudinal axis of the thread 2 between adjacent changes in the direction of hand or rotation. The second plate 22 is intended to prevent that the four threads touch each other and the central thread. Because if that were the case, so would Frictional effects occur which result in the pulling off of the threads, i.e. the dielectric optical waveguides, of the stationary coils 12 make it very difficult. By Using the plate 22, the dielectric optical waveguide 11 can have a certain phase relationship around each other and around the central thread 2 without the risk of contact consists. If several turns between each change in the hand or flap direction of the helical Grooves 3 are to be provided, then several intermediate plates 22 between the plate 23 and the coils 12 can be arranged with a corresponding gear drive.

In the embodiment described, the drive is designed so that an angular rotation of · = · the Plate 22 for each angular rotation θ of plate 23 results.

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Although the extrusion process and apparatus for Implementation of the method specifically described in relation to the manufacture of threads with a reversible lay have been, the basic idea of the pre-. lying invention in the same way in the production insert of threads with helical grooves, the lay of which is not reversed.

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Claims (12)

MANITZ, FINSTERWALD & QRÄMKOW GERMAN PATENT LAWYERS DR. GERHART MANITZ · DIPL-PHYS. MANFRED FINSTERWALD · DiPL-ING., OlPL.-WiRTSCH.-iNG. WERNER GRÄMKOW - DIPL-ING. DR. HELIANE HEYN · Dipl-chem. BRITISH CHARTERED PATENT AGENT JAMES G. MORGAN - B. SC. (PHYS.). DMS APPROVED REPRESENTATIVE AT THE EUROPEAN PATENT OFFICE REPRESENTATIVES BEFORETHE EUROPEAN PATENT OFFICE MANDATAIRES AGREES PRES LOFFICE EUROPEEN DES BREVETS Munich, June 7th, 1979 P / Sv - N 2188 NORTHERN TELECOM LIMITED Dorchester Boulevard West Montreal, Quebec1, Canada Hreckens 1, for a long-distance production of a process for a 3 Ft optical cable, an optical cable and an elongated thread for an optical cable claims 1. Method of making an elongated thread for an optical cable with a thread surface that has a plurality of helical grooves, wherein a plastic is extruded through a molding tool 909850/0852 _ ₂ _ MANlTZ ■ FiNSTERWALD · HEYN · MORGAN · 8000 MÖNCHEN 22 - ROBERT-KOCHiSTRASSE 1 · TEL (089) 224211 - TELEX 05-29672 PATMF DIPL-ING. W. GRAMKOW 7000 STUTTGART 50 (BAD CANNSTATT) SEELBERGSTR. 23/25 TEL (07 11) KKH CENTRAL TICKET OFFICE BAYER. VOLKSBANKEN - MÖNCHEN ■ ACCOUNT NUMBER 7270 · POSTSCHECK; MONKS 770 62-805 _ ο - is formed with a multi-fingered opening is characterized in order to give the extruded plastic the grooved surface net that on one of the stationary mold (9) distant point where the extruded thread (1, 2) is already relatively rigid and the thread (1, 2) is twisted, in order to give the grooves (3) a helical shape when the extruded thread (1, 2) leaves the forming tool (9). 2. The method according to claim 1, characterized in that that the plastic (2) is extruded around a central, twisted wire (1), which with one of the plastic extrusion comparable speed is pulled through the molding tool (9). 3. The method according to any one of claims 1 or 2, in particular for the production of a thread in which the direction of lay of the grooves periodically extends along the thread changes, characterized in that at the point of the thread (1, 2) periodically first in a direction and then twisted in the opposite direction to turn the helical shape into a helical shape with to modify periodic change of the lay direction. 4. With the method according to any one of claims 1 to 3 Manufactured optical cable with a central thread, characterized in that optical in the grooves Waveguides (11) are arranged. 909350/0852 5. Elongated thread for an optical cable with a reinforcing element surrounded by a plastic sheath, and with several, in an outer surface the casing formed grooves, each having the shape of a screw, each screw its Direction of lay along the thread changes, characterized in that the reinforcing element is a single, centrally arranged, stranded wire (1) is. 6. Device for producing an elongated Thread for an optical cable with a thread surface that has several helical grooves, with an extrusion device with a molding tool which is designed with a multi-finger opening, in order to give the extruded plastic the grooved surface, characterized in that the molding tool (9) is stationary that in the flow direction behind the extrusion device (9) a rotating device (6) is arranged with an element (16) which is supported for rotation about the feed path of the thread (1, 2) is, and that the element (16) is an engagement device (18) which grasp the thread (1, 2) and can be driven in order to twist the thread (1, 2), to give the grooves (3) the helical shape when the extruded material from the extrusion device (5) exit. 7. Apparatus according to claim 6, characterized in that the element (16) for performing a reciprocating Rotation is attached to the feed track. 909850/0852 8. Device according to one of claims 6 or 7, characterized in that the engagement device has a plurality of ribs which are inwardly prestressed by springs has, which are provided on their inner edges with cutting edges (19) with a narrow cross-section, which in the respective grooves (3) in the thread (1, 2) can come into engagement. 9. Device according to one of claims 6 or 7, characterized in that the engagement device has a plurality of ribs which are inwardly prestressed by springs with narrow cross-section wheels mounted on their inner edges to move into the respective grooves to be fixed in the thread. 10. Device according to one of claims 6 or 7, characterized in that the engagement device. has several wheels which can grasp a thread (1, 2) on its surface with gripping forces, which are sufficient to twist the thread (1, 2), but not sufficient to form the grooved surface of the thread (1, 2) to permanently distort. 11. Device according to one of Claims 6 to 10, characterized by a cooling container between the extrusion device (5) and the rotating device (6) to cool the extruded thread (1, 2), whereby the thread (1, 2) on the twisting device (6) is sufficient is rigid to enable its engagement with the engagement means. 909850/0852 12. Device according to one of claims 7 to 11, characterized by a connecting mechanism (B, C) between the extrusion device (5) and the rotating device (6) showing the rotation of the element (16) to the extrusion speed of the plastic relates. 909850/0812