GB2119419A

GB2119419A - Provision of a helical thread on a rope or cable

Info

Publication number: GB2119419A
Application number: GB08310786A
Authority: GB
Inventors: Wilhelm Eckhardt
Original assignee: Kuester and Co GmbH
Current assignee: Kuester and Co GmbH
Priority date: 1982-04-22
Filing date: 1983-04-21
Publication date: 1983-11-16
Also published as: JPS5915588A; GB2119419B; ES8407135A1; FR2525506A1; DE3214967A1; ES521754A0; DE3214967C2; GB8310786D0

Abstract

A method of providing a helical thread on a rope or cable (3) comprises initially winding a helical coil (1 or 2) to have an internal diameter which is somewhat greater than the external diameter of the rope or cable (3). The coil is then cut to the desired length and pushed onto the rope or cable up to a predetermined place. Thereafter, the coil is pressed fast onto the rope through external force at this place. <IMAGE>

Description

SPECIFICATION Provision of a helical thread on a rope or cable The present invention relates to a method of providing a rope or cable, particularly a braided wire cable, with a helical thread.

Ropes or cables with applied pitch helices, socalled pitch cables, are known. They are used for a variety of purposes, especially as quasi-flexible toothed rack. In some cases they are used as flexible screws.

The application of the pitch helix to the rope or cable is carried out, according to the known art, turning a coil with a wire in a stranding machine in one plane around the rope or cable, which in its turn is continuously advanced perpendicularly to this plane. From these two relative movements-constant advance of the rope or cable plus, perpendicularly thereto, winding around of the wire at constant rotational speed- there results a helix of constant pitch on the rope or cable.

This method has, however, several disadvantages. For one thing, the pitch of the applied helix is not uniform at the start of the stranding, in particular for as long as constant values have not been reached for the rope or cable advance and for the rotational speed of the coil with the helix wire.

Above all, it is disadvantageous that the entire rope or cable must be wound around by the wire during this stranding operation, including locations where the pitch helix is not actually needed.

Locations free of a helix are needed for many types of actuating pulls and the like, especially at both ends of the cable, because fittings, retaining bushes and so forth are often pressed into place at these locations. The manufacture of such actuating pulls therefore takes place in the manner that the required lengths are initially cut off from the continuously wound pitch cable, then the previously wound-on pitch cable is laboriously removed again from both the ends over a length of some centimetres and the fittings are plugged onto the free cable and pressed together.

A further disadvantage is that the helix is often really needed only at one or two locations on the cable where, for example, toothed wheels, pinions or the like engage, which often do not have to perform even an entire revolution during displacement of the cable. Nevertheless, the entire cable length therebetween must be wound round by the helix wire. A subsequent removal of the wire over an often relatively long distance would be uneconomical.

There is accordingly a need for a method by which a pitch helix can be applied to a rope or cable only at the location where it is really needed for the fulfilment of the relevant function.

According to the present invention there is provided a method of providing a rope or cable of given diameter with a helical thread, the method comprising the steps of winding a wire to form a helical coil with an internal diameter larger by a predetermined amount than the given diameter, cutting the helical coil to a predetermined length, causing the helical coil to be pushed over the rope or cable to a predetermined position thereon, and causing the helical coil to be firmly located in this position by the action of external force on the coil.

In a preferred example, a helical coil is wound from wire to have an internal diameter which is somewhat greater than the external diameter of the rope or cable to be provided with a pitch helix, the coil is cut to the desired length and pushed over the rope to the place predetermined by the function, and the coil is then pressed fast at this place through external forces. Preferably, the coil is reeled up in a form of thread-rolling machine or is hammered on.

In such a method exemplifying the invention, the pitch helix is no longer wound indiscriminately over the entire length of the rope or cable but is applied only at a selected location. Consequently, the previously necessary removal of portions of the helix from those locations at which, for example, fittings are to be pressed on is now redundant. In addition, it is now possible to apply the helix only in the length in which it is really needed. The often appreciable length between two such coils on a rope or cable is thus without a helix, whereby savings are achieved in respect of both weight and cost.

A method exemplifying the present invention will now be more particularly described with reference to the accompanying drawings, in which: Fig. 1 is a cross-sectional view of two helical coils; Fig. 2 is a view of a length of rope to which the coils are to be applied by the method exemplifying the invention; and Fig. 3 is a view of the length of rope with the upper coils as a finished pitch cable.

Referring now to the drawings, there is shown in Fig. 1 two helical coils 1 and 2, which are prefabricated as individual parts and are cut or ground to length.

A rope 3, to which the coils 1 and 2 are to be applied, is illustrated in Fig. 2. It is in that case essentiai that the internal diameter d of the coils 1 and 2 is always just so much greater than the external diameter D of the rope that the coils can be pushed onto the rope.

Fig. 3 shows the coils 1 and 2 on the rope 3.

They are pushed exactly to predetermined places A and B at which they later have to fulfil a function, for example, engage with a toothed wheel.

Through the effect of external force on the coils, the coils are influenced in their external shape. In the case of Fig. 3, it is assumed that the coils have been rolled fast by a thread-rolling machine and that the tool of the machine had a trapeziumshaped cross-section. Consequently, the coils rolled fast have a trapezium-shaped structure in the finished state and represent a trapezoidal thread with sufficiently precise pitch on the rope.

Claims

1. A method of providing a rope or cable of given diameter with a helical thread, the method comprising the steps of winding a wire to form a helical coil with an internal diameter larger by a predetermined amount than the given diameter, cutting the helical coil to a predetermined length, causing the helical coil to be pushed over the rope or cable to a predetermined position thereon, and causing the helical coil to be firmly located in this position by the action of external force on the coil.

2. A method as claimed in claim 1 , wherein the helical coil is rolled in a thread-rolling machine.

3. A method as claimed in claim 1, wherein the helical coil is hammered on.

4. A method substantially as hereinbefore described with reference to the accompanying drawings.

5. A rope or cable provided with a helical thread by a method as claimed in any one of the preceding claims.