IMPROVEMENTS IN WIRE ROPES, STRANDS AND WIRE ROPES PRODUCED THEREFROM

United States Patent 3834149

The invention relates to the construction of wire rope strands and ropes produced therefrom in which each strand is constructed in known manner from steel wires but includes at least one control element in the form of a metallic zinc or aluminium element which may be in the form of a wire or wires or a foil wrapping or coating to prevent or reduce oxidation of the steel wires, the control element being conductively in contact with the steel wires and being surrounded by steel wires to protect it against abrasion.

05/310145

09/10/1974

11/28/1972

Click for automatic bibliography generation

Dawson & Usher Limited (Sunderland, EN)

57/213

57/212, 57/217, 57/220

D07B1/06; D07B1/00; (IPC1-7): D07B1/06

57/139,144,145,146,147,148,166

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3468119	STEEL-CORED ROD AS A COMPONENT OF AN ALUMINUM CABLE,THE CABLE AND PROCESS OF MAKING THE ROD	September 1969	Kuratomi
3358435	Cord composed of filaments or strands of different diameters	December 1967	Peene
3352098	Multi-element wire line having compacted strands	November 1967	Gilmore
3307343	Corrosion resistant wire rope	March 1967	Gilmore et al.
3295310	Wire rope particularly useful for independent wire rope core	January 1967	Beighley
3293837	Method and apparatus for making wire rope	December 1966	Vennett

Watkins, Donald E.

Haucke, Gifford, Patalidis & Dumont

What is claimed is

1. A wire rope strand comprising a plurality of steel wire components and at least one control element, said steel wire components and control elements laid in known manner to form a strand, said control elements so arranged in the strand that each steel wire component is conductively in contact with an associated control element which is surrounded by steel wire components, at least one of the control elements comprising a plurality of wire elements laid between two adjacent layers of steel wire components as an additional layer.

2. A plurality of steel wire strands laid in known manner to form a wire rope, each strand comprising a plurality of steel wire components and at least one control element, said steel wire components and control elements laid in known manner, said control elements so arranged in said strand that each steel wire component is conductively in contact with an associated control element which is surrounded by steel wire components, said wire rope having a core of wire rope surrounded by a foil control element.

3. A wire rope strand comprising a plurality of steel wire components and at least one control element, said steel wire components and control elements laid together in known manner to form a strand, said control elements so arranged in the strand that each steel wire component is conductively in contact with an associated control element, said control elements enveloped by steel wire components, said control elements formed from one of a group of non-ferrous metals consisting of zinc and aluminium and at least one of said control elements comprising a wire element.

4. A wire rope strand as claimed in claim 3 wherein one of said control elements comprises a foil of one of said non-ferrous metals.

5. A wire rope strand as claimed in claim 3 wherein one of said control elements comprises a coating of one of said non-ferrous metals applied to the outer surface of an inner layer of steel wire components in said strand.

6. A wire rope strand as claimed in claim 3 wherein said steel wire components are galvanized steel wires.

7. A wire rope strand as claimed in claim 3 wherein one of the control elements comprises a plurality of wire elements laid between two adjacent layers of steel wire components as an additional layer.

8. A plurality of wire rope strands laid in known manner to form a wire rope, each strand comprising a plurality of steel wire components and at least one control element, said steel wire components and control elements laid together in known manner to form a strand, said control elements so arranged in each strand that each steel wire component is conductively in contact with an associated control element, said control elements enveloped by said steel wire components, said control elements formed one of a group of non-ferrous metals consisting of zinc and aluminium and at least one of said control elements comprising a wire element.

9. A wire rope as claimed in claim 8 wherein said rope has a core element comprising a fibre rope.

10. A wire rope as claimed in claim 8 wherein said rope has a core element comprising a wire rope.

11. A wire rope as claimed in claim 8 wherein said rope has a core element comprising a wire rope covered by a control element formed by a foil in one of said non-ferrous metals.

This invention relates to wire rope strands and wire ropes produced therefrom.

In the construction of a stranded wire rope a plurality of steel wires are laid in various formations or constructions to form a strand and a number of strands are laid to form a rope.

It is known that ferrous metals will oxidize in the presence of an aqueous solution of an electrolyte and that such oxidation can be prevented or retarded in a number of ways which can be physical or chemical.

The physical methods aim at coating the metal with a protective covering which resists penetration of moisture to the metal and one chemical method aims at establishing a balance between ferrous and non-ferrous metals in which the non-ferrous metal acts as a reducing agent and so prevents or delays oxidation of the ferrous metal. Examples of such chemical protection are the association of metallic zinc or metallic aluminium with the ferrous metal.

In the steel wire rope industry it is customary to cover each steel wire of a rope with a coating of zinc to protect the steel wire from oxidation. This process is called galvanizing.

A limiting factor in the galvanizing method of protection is that in service the zinc coating on the wire, in addition to chemical change, may be subject to abrasion so that the two influences act to reduce its effectiveness in protecting the ferrous metal.

The present invention provides a means for protecting the ferrous metal from corrosion and at the same time mitigates the limitations in the known method of using galvanized steel wire.

The term "control element" used throughout the description and claims refers to a metallic zinc element or a metallic aluminium element and the term "foil" includes a wrapping or coating.

According to the invention a wire rope strand comprises a plurality of steel wire components and at least one control element, said steel wire components and control element or elements laid in known manner to form a strand and said control element or elements so arranged in the strand that the steel wire components are conductively in contact with an associated control element, and the or each control element is surrounded by steel wire components.

Also according to the invention a steel wire rope comprises a plurality of said strands laid in known manner to form a rope.

The steel wires may be galvanized steel wires.

At least one of the control elements is in the form of a wire.

One of the control elements may be in the form of a foil of metallic zinc or aluminium wrapped around a strand of steel wires between the outer layer and an adjacent inner layer of steel wires or a coating of metallic zinc or aluminium.

Embodiments of the invention are illustrated by way of example in the accompanying drawings in which:

FIG. 1 is a section through a wire strand constructed according to the invention;

FIG. 2 is a section through a wire strand of different formation to that of FIG. 1;

FIG. 3 is a section through a wire rope formed from strands of FIG. 1;

FIG. 4 is a section through a wire strand of different construction to that of FIGS. 1 and 2; and

FIG. 5 is a section through a wire strand of yet another construction.

Referring to FIG. 1 of the drawings 1 denotes generally a wire strand having king control element 2 of metallic zinc or aluminium in the form of a wire and a plurality of steel wire components 3 laid around the element 2 in known manner to form a strand.

Referring to FIG. 2 a wire strand 1 is constructed similar to that of FIG. 1 except that the king element is formed by three metallic zinc or aluminium control 2 and wires twisted together to form a central strand.

Each steel wire component 3 is in contact with at least one of the metallic zinc control elements 2 and a plurality of strands 1 are laid in known manner to form a rope which may have a natural or synthetic core or an independent wire rope or strand core.

Where a wire rope or strand core is used the strand or strands in the core may be formed with a metallic zinc or aluminium element or elements in accordance with the invention.

FIG. 3 illustrates the use of six strands 1 constructed according to FIG. 1 and laid to form a rope known as a 6 × 7 construction i.e. each strand in the rope is formed with seven wires, six of which are steel wires 3 laid around one control element 2. Six strands are used to construct the rope which has a fibre core 4. The six strands being laid around the core 4 in known manner.

It will be seen that the control element 2 in each strand is enclosed or encased by the steel wire components and is therefore protected from abrasion when in use but is subject to chemical change by oxidizing and in so doing prevents or retards oxidation of the steel wire components.

The core 4 may be formed by a wire rope construction in which each strand has at least one control element.

Where a steel wire rope or strand core is used the control element can be on the outer surface of the core since it is not subject to abrasion in use and may be in the form of a foil wrapped around the core rope.

Alternatively the core rope may be dipped in a zinc bath to form a zinc coating thereon or the core rope may be formed in conventional manner using galvanized steel wires.

Referring to FIG. 4 which illustrates a wire strand 1 having nineteen wires in its construction, the king wire is a steel wire component 3 and has a first layer of six wires around the king wire, three of which are control elements and three are steel wire components 3 laid alternatively and an outer layer of twelve wires each of steel wire components 3.

Six strands are laid to form a 6 × 19 construction rope which may have a core of fibre rope or of steel rope or strand as previously described.

FIG. 5 illustrates a larger diameter strand construction which has 37 wires. The king wire is formed from a wire control element 2, an inner layer 5 is formed in known manner from steel wire components 3, an intermediate layer 6 is formed of steel wire components 3 in known manner on the inner layer 5 and a control element in the form of a foil 7 is formed around the intermediate layer 6. The foil 7 may be in the form of a zinc or aluminium foil wrapped around the intermediate layer 6 or the strand so formed may be dipped in a zinc bath to form a coating around the intermediate layer. An outer layer 8 of steel wire components 3 is then formed around the foil 7.

The strands so formed are laid to form a rope. In a 6 × 37 construction 6 strands each having a king wire, an inner layer of six wires, an intermediate layer of twelve wires surrounded by a foil control element and an outer layer of 18 wires are laid to form a rope. The rope may have a fibre rope or strand core or an independent steel wire rope or strand core constructed as previously described with reference to FIG. 3.

The foregoing are examples of strand constructions but the present invention is not to be considered as limited to these particular constructions as it will be seen that a variety of strand constructions are possible. The number of control elements used in a strand construction depends on the number of steel wire components in the strand and the disposition of the control elements in relation to the steel wire components depends on the number of layers in a strand.

In all of the formations the steel wire components are laid so as to be conductively in contact with a control element.

The element may be substituted by a zinc or an aluminium element or where there is more than one element, zinc and aluminium elements may be used.

For example in the construction of a strand according to FIG. 5 the foil may be of aluminium while the king wire is metallic zinc or vice versa.

To test the effectiveness of the rope construction according to the invention as a protection against corrosion of the steel wire a sample length of 6 × 7 construction rope was anchored at the half tide mark at a pier on the river Clyde so that the sample was immersed in salt water and exposed to atmosphere for equal periods of time each 24 hours. As a control a steel wire rope of identical construction but composed wholly of ungalvanised steel wire, was exposed at the same place and in the same way.

In the case of the unprotected rope corrosion began immediately and at the end of 16 weeks was well adavanced.

In the case of the rope constructed according to the invention, corrosion at the end of 16 weeks was very slight and of no technical significance.

In a second test to compare the degree of protection afforded by a zinc wire in the rope strand with the protection afforded by conventional galvanizing, practical trials were carried out on a fishing boat working off the West Coast of Scotland.

A set of trawl warps of 6 × 7 construction and made in the conventional fashion with galvanized steel wire was fished under average conditions to the point where oxidation was clearly evident.

A second set of warps of 6 × 7 construction but made according to this invention with ungalvanized steel wires surrounding a zinc wire was then fished by the same boat in the same conditions.

Whereas oxidation was clearly evident on the galvanized warps within five months there was no evidence of rust on the warps containing zinc wires in their strands in that time.

Preferably sufficient zinc wires are included in each strand to ensure that when the strand is constructed in known manner the steel wires are each conductively in contact with a zinc wire and the zinc wire is so located in the strand as to be protected by the steel wires from abrasion when in use.

Two or more zinc wires may be used instead of a single zinc wire and one or more zinc wires may form the core of a strand or rope.

In strand constructions having two or more layers an additional layer of control wire elements may be located between the outer layer and the adjacent inner layer or control wire elements may be spaced in the layer adjacent to the outer layer.

Alternatively a foil of zinc or aluminium may be wrapped around the outer surface of the layer adjacent the outer layer.

The zinc wire or foil used in the above examples may be substituted by a metallic aluminium wire or foil or the strand may be constructed using a zinc wire or wires and upon aluminium foil depending on the number of steel wires contained in the strand.

The use of zinc or aluminium elements in a strand need not be limited to protecting ropes or strands made from ungalvanised steel wire but can be used in conjunction with galvanised steel wires, particularly in applications where conditions effecting corrosion are more than normally severe.

In using control elements in a strand construction it will be obvious that the tensile strength of the rope will be effected but this can be overcome by using higher tensile steel for the steel wires.