EP3017108B1 - Traction rope comprising a one-piece core - Google Patents

Description

The present invention relates to a cable with strands wound on a central core, more particularly intended to be integrated into a cable transport installation, without however being limited thereto. The cable which is the subject of the present invention is thus specifically able to be able to effectively support the attachment of vehicles (cabins, seats) transporting people or goods by means of fixed or disengageable clamps, or jaws, these fasteners enclosing its surface of so as to support the weight of these vehicles and their contents, while ensuring their translation throughout the installation, without there being any slippage between the cable and the aforementioned fasteners. This directly implies a short and long term resistance of the cable object of the present invention, and of its core, to the pressure exerted by the aforementioned pliers or jaws.

In a certain number of systems using one or more cables, the movement of these at constant speed can be of a nature to generate noise and / or vibrations which are harmful to the environment of the installation, as well as to mechanical strength of some of its constituent components.

This situation is encountered in particular for cable transport installations, whether of people or materials, such as ski lift installations, for which operation at a very high service rate is frequent, and for which the expected service life can reach several decades.

The outer layer of a traction cable or carrier-tractor according to the most common state of the art, assembled in a helix around a core, is made up of a certain number of strands, typically from 3 to 16 strands . Such a helical assembly of strands around a core necessarily generates a "valley" between each pair of adjacent strands, valleys which constitute all along the cable as many geometric deviations from an ideal envelope of cylindrical shape of the outer surface thereof.

The passage of each of these valleys on each roller of the installation will therefore generate a movement of the latter which can reach an amplitude of several millimeters. As can be seen, depending on the running speed of the cable, each of the rollers of the installation will therefore be driven by a periodic oscillation movement, the frequency of which may rise, depending on the case, to several tens. Hz, or even, in some cases, several hundred Hz.

These vibrations, the generation of which is inherent in the structure of traction cables or tractor carriers according to the most widespread state of the art, although lessened by a judicious choice of lining materials for the guide rollers of the cable installation concerned, may however be likely to disturb its environment (for example: generation of noise near homes) and / or accelerate the wear or fatigue of some of its components .

To solve this problem, we know the document FR 2 769 027 which describes a cable for a gondola comprising a central core extended by peripheral inserts between which the strands are interposed during cabling. However, the document FR 2 769 027 emphasizes the need for thorough compaction of the cable during its manufacture, with the aim of ensuring "mutual nesting of the strands, the inserts and the central core of the cable", which directly implies a very strong pinching action of each fin between the two strands which border it, this making the manufacturing process very unstable. This technical choice of a thorough compaction is also likely to cause in the short or medium term either the ejection or the complete shearing of the fins. Such a thorough compacting operation is therefore very delicate and does not generally make it possible to obtain a cable of homogeneous section, the vibrations then not being reduced and the cable not having the required durability.

In addition, the devices of the prior art also pose a problem in terms of resistance to sliding, because they are generally not sufficiently able to withstand the vertical pressure of the clamps of the transport cabs.

US 2,136,865 discloses a traction cable comprising a one-piece core provided with a central core having on its periphery a series of fins and strands arranged around the core

The aim of the present invention is therefore to remedy these drawbacks by proposing a stranded cable making it possible to minimize or even eliminate the vibrations and noises generated by its passage over the guide rollers of an installation of the towed or teleported type, thus a method of manufacturing such a cable and a suitable core.

To this end, the invention relates to a cable according to claim 1.

• les ailettes peuvent présenter un module de compression différent de celui du noyau central, qu'il soit inférieur ou supérieur
• le noyau central comprend en outre un toron noyé dans le noyau, le toron étant dimensionné pour participer à la reprise des efforts de traction transmis par le câble ou pour le lester,
• le noyau central comprend en outre des fibres, choisies de façon à participer à la reprise des efforts de traction transmis par le câble ou pour le lester,
• les matériaux constitutifs de l'âme sont des polymères comprenant des charges destinées à améliorer leurs caractéristiques mécaniques en compression, et/ou à leur conférer des propriétés de résistance aux rayonnements UV et/ou à les rendre conducteur de l'électricité, et/ou ou à leur conférer des propriétés lubrifiantes,
• le nombre de torons est compris entre 3 et 16 et est de préférence égal à 6,
• les torons sont compactés individuellement avant assemblage avec l'âme monobloc.

The cables according to the invention can also incorporate the following characteristics, taken individually or in combination:

• the fins may have a compression modulus different from that of the central core, whether it is lower or higher
• the central core further comprises a strand embedded in the core, the strand being dimensioned to participate in the absorption of the tensile forces transmitted by the cable or to ballast it,
• the central core also comprises fibers, chosen so as to participate in the absorption of the tensile forces transmitted by the cable or to ballast it,
• the constituent materials of the core are polymers comprising fillers intended to improve their mechanical characteristics in compression, and / or to give them properties of resistance to UV radiation and / or to make them conductive of electricity, and / or to give them lubricating properties,
• the number of strands is between 3 and 16 and is preferably equal to 6,
• the strands are individually compacted before assembly with the monobloc core.

• la figure 1 est une vue en perspective d'un premier mode de réalisation d'un câble selon l'invention,
• la figure 2 est une vue en coupe transversale de l'âme du câble correspondant à la figure 1,
• la figure 3 est une vue en coupe transversale d'un deuxième mode de réalisation d'une âme selon l'invention.

The invention will be better understood with the aid of the description which follows, given solely by way of example and with reference to the appended drawings, in which:

• the figure 1 is a perspective view of a first embodiment of a cable according to the invention,
• the figure 2 is a cross-sectional view of the core of the cable corresponding to the figure 1 ,
• the figure 3 is a cross-sectional view of a second embodiment of a core according to the invention.

As can be seen in figure 1 , in a first embodiment, a cable 1 according to the invention comprises a one-piece core 2 and a series of six strands 3, with round or preferably compacted wires, wound in a helix around this core 2.

The choice of strands of the compacted type makes it possible to ensure the direct interchangeability of the cable according to the invention, whether in diameter, metric mass, and minimum breaking load with cables of conventional construction, already in place on existing devices.

In the context of the present invention, the term “one-piece” denotes an element which cannot be disassembled into several sub-assemblies without being damaged.

As can be seen more precisely in figure 2 , the core 2 itself consists of a central core 4 provided on its periphery with six regularly spaced fins 5, the side walls of which form between them as many receiving grooves 6 of substantially circular shape. The fins 5 can be made of the same material as that of the central core 4 or else of one or more materials, the modulus of which is compression is preferably less than that of the central core 4, which means that these fins will then be more easily compressible than the core 4.

The peripheral end of each fin 5 is shaped in an arc of a circle, so that when the strands 3 are inserted into each of the receiving grooves 6, by temporarily deforming the fins 5, the cable 1 thus obtained has an outer casing of substantially cylindrical shape, which therefore hardly comprises any more valleys.

In addition, the internal diameter of the circular part of the receiving grooves 6 is chosen so as to be close to, and slightly smaller than that of the strands 3 that they are to receive so that the contact is as close as possible between the side walls of the fins 5 and strands 3, without a thorough compaction operation according to the prior art while guaranteeing obtaining a homogeneous section and a profile of very great regularity over the entire length of the cable.

The one-piece core 2 can be manufactured by any process suited to the nature of the material (s) from which it is made. It will preferably be made of synthetic materials, a term which here covers all thermoplastic compounds, thermosetting compounds, elastomers and vulcanizable compounds. Mention will in particular be made of polymers such as polyolefins and, in particular, polyethylene.

In a preferred embodiment, these materials can be added with fillers, so as to give them particular properties, for example resistance to UV radiation, electrical conductivity, resistance to compression, or lubrication.

The strands 3 may conventionally consist of an assembly of wires of different diameters wound in a helix around a central wire. They are preferably metallic and more particularly preferably made of steel. They can be individually the subject of a compacting operation, so as to increase the metal section of a cable of given diameter.

In a second embodiment described in figure 3 , a core 7 according to the invention further comprises a strand 8 embedded in its central core 4. This strand 8 may conventionally consist of an assembly of wires of different diameters wound in a helix around a central wire. It is preferably metallic and more particularly preferably made of steel. Its dimensioning is generally carried out in such a way that it participates in the absorption of the tensile forces transmitted by the cable, but may also have the sole purpose of ballasting it.

In a third embodiment (not shown), the cores according to the invention can also comprise fibers, metallic or not, inserted longitudinally in the central core 4. As previously, their dimensioning is generally carried out such that they participate in the recovery of the tensile forces transmitted by the cable, but may also have the sole purpose of ballasting it.

The cable according to the invention can be spliced to form a closed loop by coupling the opposite ends of its strands.

It is compatible with the various principles of fixed or disengageable clamps according to the state of the art, the interface of these with the metal part of the cable being unchanged with respect to the cables of the prior art.

The cable according to the invention is more particularly intended to be integrated as a pure traction cable or as a towing carrier cable in an installation for the transport of persons by cables such as a mechanical lift installation such as, for example, but of not limited to a gondola or a cable car.

Transport installations such as ski lifts are in fact held by a carrier-tractor cable, that is to say that the cable ensures the reach of the cabin but also its drive upwards.

For installations such as cable cars, two cable systems are available, namely one or two supporting cables and one or more traction cables. The carrier cable is fixed and stretched between the departure station and arrival station of the facility and does not move. The traction cable, which provides traction for the cabin, is attached to the cabin trolley and forms a drive loop stretched between the two stations.

In addition to these applications, the cable according to the invention is capable of being used in numerous other applications such as an urban transport system, for example, and is therefore not limited to these aforementioned uses.

Claims (8)

1. A traction cable (1) comprising a single-piece core (2) comprising a central inner-core (4) fitted on its periphery with a series of regularly spaced fins (5) forming reception grooves (6) therebetween, whose cross-section is at least partially circular, and strands (3) disposed around said core (2) by inserting into each of said reception grooves (6), such that the assocation of said core (2) and said strands (3) exhibits an outer envelope in a substantially cylindrical shape, the strands (3) being embedded in the reception grooves (6), though without causing the fins (5) that separate them to waver, the diameter of the reception grooves (6) being less than that of the strands (3).
2. A cable according to claim 1, for which said fins (5) have a different compression modulus than said central inner-core (4).
3. A cable according to one of the claims 1 to 2, of which the central inner-core (4) further comprises a strand (8) sunk into said inner-core (4), said strand (8) being sized to participate in the absorption of traction forces transmitted by the cable or to weight it down.
4. A cable according to one of the claims 1 to 3, whose central inner-core further comprises fibers, chosen so as to participate in the absorption of traction forces transmitted by the cable or to weight it down.
5. A cable according to one of the claims 1 to 4, for which the materials composing said core (2) are polymers comprising loads intended to improve their mechanical properties in terms of compression, and/or to grant them UV radiation resistance properties and/or to make them electrically conductive, and/or to grant them lubricating properties.
6. A cable according to any of the claims 1 to 5, of which the number of strands is comprised between 3 and 16 and is preferably equal to 6.
7. A cable according to one of the claims 1 to 6, of which the strands (3) are individually compacted before assembly with the single-piece core (2).
8. The use of a cable according to one of the claims 1 to 7 as a pure traction cable or as a conveyor cable.

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