JPH028073B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cables, especially cables whose wires are covered with individual sheaths of plastic or rubber material.

In the previously proposed cable, the strands or individual cores are approximately circular in cross-section where they are fed. Such cable constructions have a number of drawbacks. The cable geometry is not particularly stable as the individual strands are subject to deformation and rotation relative to each other. Since the extent to which this will occur cannot be predicted, the performance of such cables cannot be accurately predicted. Additionally, since the strand-to-strand contact occurs in a very small area, the strand-to-strand pressures are high, which, in combination with the movement of the strands relative to each other, results in wear of the strands. This wear increases when the cable passes around the pulleys because such deflection of the cable causes relative movement of the strands. Furthermore, the contact area between the strand cover and the pulley is limited and vibrations result in high stresses. In fact, the interstrand forces of such ropes allow only limited deflection of such cables. This kind of cable also
Allows only limited transfer of loads between stranded wires.

The present invention, however, firstly consists in forming a layer or layers of strands twisted together, each strand of substantially circular cross-section of the layer or at least one layer being made of plastic or rubber. With respect to cables of the type covered with separate sheaths of material, the construction means are such that at least some of the strands of said circular cross-section are attached to a sheath of a non-circular cross section that extends spirally along the strands of the cable, and the sheaths of adjacent strands of the twisted layer lock together to fix the spatial relationship between the strands within the cable. The point is that it is.

The invention also provides a second cable of the type in which a plurality of strands are each covered with a separate sheath of plastic or rubber material and the sheathed strands are twisted together to form a single cable. Regarding the manufacturing method, the gist thereof is to pass at least some of the stranded wire through an extrusion die having a non-circular cross section, and during this passage, the extrusion die is rotated and the stranded wire is wrapped around the stranded wire. A discrete sheath of non-circular cross-section extending helically along the strand is extruded to cover the strand, and the sheathed strand is then twisted together with adjacent strands so that they are adjacent to each other. The sides of the sheath are interlocked to create a layer of strands with substantially fixed spatial relationship of the strands to each other within the cable.

Some embodiments of the invention will now be described in detail with reference to the accompanying drawings.

Referring first to FIG. 1, in a first embodiment of the cable the strand 10 is formed from a plurality of elements 11 twisted together. The element may be a metal wire or a bundle of synthetic material or a combination of such wires and bundles. Suitable metal wires are steel wires, especially high-strength steel. The bundle of synthetic material is advantageously formed from yarns spun from filaments of plastic material, such as aromatic polyamide (eg KELVAR). The strands may also be made from different materials or combinations of materials and/or different amounts of strands to enhance load distribution.

All or every other element 11 can be covered with a sheath of plastic or rubber material before being formed into a strand. This reduces inter-filament friction and increases inter-filament load transfer.

The stranded wire 10 does not necessarily have to be formed from a plurality of metal wires or a plurality of twisted bundles of metal wires. The strands 10 may also be formed by several bundles of yarns or strands of synthetic material arranged parallel to each other (not shown). The strands 10 thus formed may have a shrunken or extruded cover over the bundle or strands to hold them together.

After forming the stranded wire 10, the extrusion die 12 (second
Figure). A suitable molten plastic or rubber material is fed to the die under pressure from a heated screw feeder in the conventional manner. A suitable material is
Alone or in compounds, thermoplastic materials such as polyester, polyether, polypropylene, polyetheretherketone, nylon and polyvinyl chloride, polychloroprene, natural and synthetic rubbers, polyurethane, HYPALON and EPDM (ethylene propylene) - thermoset and vulcanizable materials such as diene terpolymers); and chemically cured materials.

The die 12 has a generally trapezoidal shape with straight convergent sides 13 joined at its narrow ends by a short convex end face 14 and at its wide end by a concave arcuate end face 15. The dimensions of the dao are such that the die has a larger area than the cross section of the strand 10 and the strand 10 is guided into the die such that there is a gap between the outer surface of the strand and the surface forming the die. (See Figure 2). The convergence of the side surfaces 13 and the curvature of the arcuate end surfaces 14, 15 are selected according to the considerations described below.

The stranded wire is fed to the die at a predetermined feed line speed. At the same time, the die 12 rotates at a predetermined rotational speed and in a direction of rotation that is the same as the direction of the strands or that is compatible with the layers of the cable.

As a result of this, a sheath 20 is extruded around the strands, having a shape corresponding to the shape of the die and extending helically along the strands. This is clearly shown in FIGS. 3 and 4, which show that the sheath 20 has convergent sides 16,
It can be seen that it has a narrow concave end surface 17 and a wide convex end surface 18. The convergence of the sides 16 is selected as described below.

The extruded sheath 20 penetrates into the gap between the element 11 and the strands and locks the sheath to the stranded wire. However, this locking can be increased by providing gaps between the elements to allow deeper penetration of the sheath into the strands. Alternatively or additionally, a chemical bonding agent may be provided on the wire prior to extrusion to form a bond between the strands and the sheath.

Additionally, lubricant can be inserted into the wire before applying the sheath 20, so that the lubricant is retained within the strand by the sheath after extrusion of the sheath.

As best seen in FIG.
The rotation of the sheath causes the sheath to be extruded in a spiral around the strands. Since the feed line speed of the stranded wire and the rotation speed of the die are controlled, the pitch of this helix can be arranged to the required pitch. The method for determining the required pitch is detailed below.

The sheathed strands are then layered to form a cable. In FIG. 5, a 1+6 cable is shown (i.e. one cable has a sheathed core surrounded by six equally spaced strands 22). However, while any suitable cable construction may be used, it is advantageous for the wires to have such dimensions, number and geometry as to allow for the introduction of tack, so that the cables can be connected over long distances. For example, two or more stranded wire layers can be provided, as shown in dashed lines in FIG.

In each strand 22, the convergence angle of the side surfaces 16 and the curvature and shape of the arcuate surfaces 17 and 18 are:
The selection is based on the cable diameter and core diameter. However, it is recognized that if the sides 16 of the sheath 20 can converge to a point, it is not necessary to include the core wire 21. Additionally or alternatively, a plurality of stranded wire layers can be provided, with the angle of convergence of the side surfaces 16 and the wide and narrow surfaces 17, 18
The arcuate shape of is selected accordingly.

The strands 22 are stranded by feeding the required number of strands into a conventional cable stranding machine. The helical pitch of the sheath during sheath extrusion is chosen to be equal to the pitch of the strands 22 when twisted into a cable.

Clamp the rope structure together to the strands 10 by using a helical pitch of the strands that is slightly different from that defined by the cable layer, as well as by the use of back twists or forward twists during the crimping process. It is possible to apply a tendency force. When applying such modifications, it is desirable to heat-cure the sheath after deposition to fix the twist of the sheath.

The sides 16 of adjacent sheaths in the stacked cable face and engage. Furthermore, the wide surface of the strands forms a continuous cylindrical outer surface for the cable. This construction has a number of advantages, among them: 1. The cable has a suitable geometry, since the spatial interrelationships between all the strands are fixed by the sheath, and therefore the strands cannot practically move relative to anything else,
Its position within the cable cannot be changed. The cable's performance characteristics are then stable and predictable.

2. Since the strand forces are spread over a relatively large area, the stress between the strands is reduced and the life of the strands and therefore of the cable is increased.

3 As a result of this, the strands can move relative to each other with relative ease, and the cable can thus easily deflect around the pulleys, reducing the increase in interline forces caused by such deflections. decrease.

4. The cylindrical outer surface provides a large area for frictional engagement between the cable and, for example, the drive pulley, thereby reducing the stresses created in the sheath by the transmission of torque from the drive pulley to the cable.

5. The cylindrical outer surface creates a large bearing surface for the support pulley, leading to a reduction in the bearing pressure between such pulley and the cable, or allowing the use of larger pulley loads for the same bearing pressure. This advantage allows such cables to be used with V-section pulleys, which, unlike previous cables, pinch such cables and crush the strand geometry, i.e. the cable It cannot be used because of the high bearing pressure that tends to flatten it.

6. Due to the cable's substantially solid cross-section, it is difficult for dust and other hazardous materials to enter the interior of the cable.

7. The cable shown at the top of the drawing is easier to connect when compared to a cable in which the individual strands are not sheathed, but the entire outer surface of the cable is covered by a sheath.

8 Furthermore, compared to such cables, failure of any one sheath does not cause corrosion of all the strands.

9. The mutual engagement of all the strands (including the core wires) increases the load between the strands, so that the negative is transferred evenly between the strands.

There are many variations to the arrangement described above, among them the following:

The sheaths of strands 10 need not all have the same cross-section. With reference to FIG. 6, in one embodiment every other strand 10a is provided with a sheath 20a of circular cross section. The intermediate twisted wire 10b is
It has a concave side surface 16b and has an adjacent stranded wire 10 therein.
Sheath 2 in which the circular sheath 20a of a is accommodated
0b. In this way, the strands of the layer 10
a, 10b are locked in the same way as the strands 10 in the embodiment of FIGS. 1-5. The outer surface 18b of the intermediate strand 10b has an extended arcuate length that covers the adjacent strand 10a and provides a cable with a cylindrical outer surface.

Structure of stranded wires 10a, 10b and sheath 20
The molding of parts a and 20b is as described above with reference to FIGS. 1 to 5.

The outer surface 18 of the sheath may be provided with moldings to prevent water build-up between the cable and the surface over which the cable passes, such as a pulley. For example, the sheath can be formed with a groove 25 (FIG. 5) at the edge between the outer surface 18 and the side surface 16. These wipe the pulley surfaces to remove both water and dust build-up.

Additionally or alternatively, groove 26 (fifth
) can be provided for this purpose by extrusion or cutting into the surface 18. Another option is to provide this surface with a treaded pattern.

Friction between the twisted wires is achieved by grooves 21 on the side surface 16 (Fig. 5).
This can be further reduced by providing a groove in which oil is contained to provide reduced friction between the contact surfaces 16. Adjacent surfaces can be provided with grooves 27 which interdigitate with an overlap, the overlap creating a restricted outlet for the lubricant within the grooves. Additionally or alternatively, a piece of low friction material 28, such as polytetrafluoroethylene, may be provided between the adjacent surfaces 16.

The core can be provided with moldings that engage moldings on the inner surface 17 of the sheath. This allows positive locking between the core wire and the residual strand wire.

Adjacent strands or strand layers may be in opposite directions to reduce rotation.

The sheath is fitted with a closed air cell 2 to create a cable that can float completely or partially underwater.
9 can be provided.

In the embodiments described above in connection with the drawings, the forces acting inwardly on the center strand depend in part on the tension in the cable. Thus, by using suitable means for determining the pressure acting on the center strand, it is possible to obtain an indication of the rope tension and thus a warning of overtension. Such pressure can be monitored electrically, for example. Synthetic materials whose conductivity changes sharply in response to pressure are available, and such materials can therefore be incorporated into the center line to monitor the pressure.

Electrically conductive wires can be incorporated into the cable extending along its length, which wires break in the event of overstretching of the rope, thus allowing electrical monitoring of the rope stretch.

[Brief explanation of drawings]

The drawings show some embodiments of the invention, FIG. 1 being a schematic representation of part of the strands for incorporation into a first cable, and FIG. 2 showing a sheath pushed over the strands of FIG. FIG. 3 is a cross-sectional view of the stranded wire covered by a sheath; FIG. 4 is an enlarged side view of the sheathed strand; and FIG. 5 is an enlarged view of the sheathed strand. The first to incorporate the line
FIG. 6 is a cross-sectional view of a second embodiment cable incorporating sheathed strands. 10... Stranded wire, 11... Elements twisted together, 12... Extrusion die, 13, 16...
... Convergent side surface, 14, 18 ... Convex end surface, 15,
17... Concave end surface, 20... Sheath, 21... Sheathed core wire, 22... Stranded wire, 25... Groove, 27... Groove, 28... Low friction material piece.

Claims (1)

Claims: 1. Formed by a single or multiple stranded wire layers twisted together, said layer or at least one
In a cable of the type in which each strand of substantially circular cross-section in two layers is covered with a separate sheath of plastic or rubber material, at least some of the strands 10 of said circular cross-section Before being combined into a single cable, it has a sheath 20 of non-circular cross-section that extends helically along the associated strands and connects the adjacent strands 1 of the twisted layer.
A cable, characterized in that 20 sheaths are engaged with each other to fix the spatial relationship between the strands within the cable. 2. Each sheath 20 has a non-circular cross-section giving rise to two mutually spaced side surfaces 16 which, when viewed in a plane orthogonal to the cable axis, extend substantially linearly and which are adjacent to each other. 2. A cable according to claim 1, wherein the cable engages a corresponding surface of a wire sheath. 3. Every other strand 10a has a sheath 20a of circular cross-section, and each intermediate strand 10b of said every other strand has two concave side surfaces for receiving the circular cross-section sheath of an adjacent strand. A cable according to claim 1, comprising a sheath 20b having a sheath 16b. 4. The stranded wire forming the outer layer of the cable is covered with a sheath, and the outer surface of the sheath has a molded part that cooperates with the surface through which the cable passes to remove water from between the cable and the surface. 25; 26. The cable according to claim 1, wherein: 25; 26 are provided. 5 A core is provided, and the sheath of the stranded layer adjacent to the core has an arcuate surface 17 shaped radially inwardly to cooperate with the core or the sheath covering the core. Claim 1
The cable described in any one of paragraphs 1 to 4. 6. Cable according to any one of claims 1 to 5, wherein at least some of the sheaths 20 contain closed air cells 29 for floating the cable underwater. 7 In a method of manufacturing cables of the type in which a number of strands are each covered with a separate sheath of plastic or rubber material and the sheathed strands are twisted together to form a cable, with non-circular transverse passing at least some of the strands through a surface extrusion die, rotating the extrusion die during this passage around the strands, forming individual non-circular cross-sections extending helically along the associated strands; A sheath is extruded to cover the strands, and the sheathed strands are then twisted together with adjacent strands and the sides of adjacent sheaths are locked together to separate the strands in the cable. A method of manufacturing a cable, characterized in that it produces stranded wire layers with a substantially fixed spatial relationship to each other.