GB2171073A

GB2171073A - Binding head

Info

Publication number: GB2171073A
Application number: GB08504243A
Authority: GB
Inventors: Roger Pilling
Original assignee: STC PLC
Current assignee: STC PLC
Priority date: 1985-02-19
Filing date: 1985-02-19
Publication date: 1986-08-20
Also published as: GB8504243D0; AU5332886A

Abstract

A binding head for applying binder, e.g. tape or thread, to an optical fibre bundle (A), comprises a rotated arbor (A) carrying a spool (C) of binder. The binder (G) is dispensed from the spool via a lightweight dished free wheeling shroud (D) and a substantially circular brush (K) fixed to the arbor, the binder (G) being dragged across the radial bristles of the brush which thus induces a desired amount of tension but avoids the use of high inertia parts. The shroud rotates on a free wheel device so that it can rotate only in one direction relative to the arbor, so that tension is controlled during acceleration and deceleration. <IMAGE>

Description

SPECIFICATION Improved binding head This invention relates to a binding head for applying a binding material to an elongate element, particularly but not exclusively for binding a fibre optic bundle for a telecommunications cable.

The binding of electrical, telecommunications and fibre optic cables involves the use of concentric or eccentric spools or cops of yarn or tape being revolved around the elongate element to form a helical binding.

The kind of binding head being considered is the concentric type where the elongate element to be bound runs axially through the spool or cop of binding material.

In most known systems the yarn itself has to force relatively high inertia parts to move, such as pulling round the entire spool or cop of material. This involves frictional drag forces which arise in bearings, guide bushes and other parts, all of which contribute to high tension which is difficult to control during start up, running and decelerating the manufacturing process.

It is an object of the present invention to minimise the high inertia parts carried or moved by the binding material.

According to the present invention there is provided a binding head for applying a binding material to an elongate element, comprising a base frame, an arbor rotatably mounted on the base frame, drive means for driving the arbor, means for supporting a spool or cop of binding material on the arbor, and a dispenser arrangement located between said material supporting means and a point of application of the binding material to the elongate element, said dispenser comprising a substantially circular brush like element arranged so that in use the binding material will be dragged around the periphery of the brush like eiement.

In order that the invention can be clearly understood reference will now be made to the accompanying drawingss in which: Figure 1 is an axial cross section through a binding head for building the fibre optic bundle of a telecommunications cable, according to an embodiment of the invention, and Figure 2 is a view of part of the binding head of Fig. 1 from the direction of the arrow F in Fig. 1.

Referring now to the drawing the binding head comprises an arbor A driven by a motor or driveshaft E via drive pulleys E" E2 in a clockwise or anticlockwise direction depending on the helix handing required on the fibre optic bundle. The fibre optic bundle is indicated by the reference numeral H. In this embodiment we shall consider that the fibre optic bundle H is to be wrapped with an anticlockwise binding and for this purpose the arbor A is driven in an anticlockwise direction when viewed from the arrow F.

The arbor A is mounted on a base frame BF via bearings B and carries a spool or cop of binding material C which is considered to be revolving as one with the arbor A upon which it is fitted.

Binding material drawn from the spool C is designated G and has been wound onto the spool in a clockwise manner when viewed from the direction of the arrow F. In the binding process onto the optical fibre bundle H, the binding material G passes over the smooth rim of a light weight dished shroud D and onto the optical fibre bundle H on which it is being wound. The shroud D is mounted on a free wheel (unidirectional bearing) L and can rotate only in an anticlockwise direction relative to the arbor A and the bobbin or spool C, in this particular embodiment.

Fixed to the arbor where the optical fibre bundle H exists from the arbor, is a disc member J carrying radially extending bristles K.

As the binding process proceeds, the action of the optical fibre bundle H moving in the direction from right to left as shown in the drawings, through the rotating assembly, causes a spiral wrap of binding material to be wound onto the optical fibre bundle. For this to continue, the tension in the binding material G would pull loops freely from the bobbin over the lip of the shroud with a very low resultant tension, were it not for the bristles K. These halt the progress of the unwiding material and the loop, which is shown diagrammatically in the Fig. 2, pulls taught and drags its way around the shroud, bending the bristles down as it progresses. As the tip of each bristle is passed, the bristle flicks upright, assisted by centrefugal effects (inertia due to rotation) and awaits the yarn or binding material to come round again.The yarn continues to brush its way through the bristles and the force or tension which is required to achieve this is determine by the stiffness and the number of bristles radiating outwards from the disc.

Tension adjustments are therefore unnecessary during running as it is entirely preset by the type of brush in use.

The lightweight shroud D cannot be left behind by the rotating system as it accelerates up to speed because the free wheel drives it up to speed with the arbor A. Once up to speed (and during acceleration), the unwinding material G coming from the spool can rotate the shroud in relation to the bobbin if the binding material friction on the rim is great enough to cause it to rotate. On fast shut down the over-running rim tries to unwind a loop from the bobbin but reduces tension as it does so and consequently slip takes place.

This means that the binding process can be brought quickly to a standstill even though the shroud runs on, with the binding position of the binding material still being held constant by the bristles. The bristles maintain binding yarn tension even when the binding unit has completely stopped and there is no danger of harming the binding material or the optical fibre bundle, during acceleration and deceleration.

The electrical feed to the motor or driveshaft E would be coupled with the draw off speed of the optical fibre bundle, for example by means of a take up drum or haul off device and the two speeds are synchronised so that a predetermined winding pitch can be achieved.

The advantage of the invention lies in the fact that the binding material does not have to pull round the bobbin, spool or cop and the tension is controlled during start up (accelerating) running (at constant speed) and stopping (decelerating). The binding head can also be bought to rest quickly without endangering the opticsl fibre bundle being bound or the binding material such as binding yarn or thread, through over tension.

Claims

A binding head for applying a binding material to an elongate element, comprising a base frame, an arbor rotatably mounted on the base frame, drive means for driving the arbor, means for supporting a spool or cop of binding material on the arbor, and a dispenser arrangement located between said material supporting means and a point of application of the binding material to the elongate element, said dispenser comprising a substantially circular brush like element arranged so that in use the binding material will be dragged around the periphery of the brush like element.
2. A binding head as claimed in claim 1, wherein said dispenser also comprises an annular dished shroud presenting a smooth support surface on which the binding material will run between its take-off from the arbor and prior to entry in the brush like element.
3. A binding head as claimed in claim 1 or claim 2, wherein the brush like element comprises a disc secured to the arbor and supporting radially projecting bristles.
4. A binding head as claimed in claim 2 or claim 3 as appended to claim 2, wherein the lightweight dished shroud is rotatably mounted on the arbor.
5. A binding head as claimed in claim 4, wherein the rotatably mounting comprises a free wheel bearing unit which is unidirectional.
6. A binding head substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
7. A cable making apparatus comprising a binding head as claimed in any preceding claim, in combination with a take up drum, and drive means for driving the binding head and the take up drum, and control means for controlling the relative speed of the binding head and the elongate element.