CA1242956A - Plastic encapsulated wire rope - Google Patents

Abstract

ABSTRACT

A wire rope is provided having a central core strand about which are wound outer strands. Spacer strands are present in the gaps between such core strand and outer strands to assume the uniformity of such gaps. A coating, usually of a suitable thermoplastic, is extruded into such rope to provide a spacer between such core and such outer strands, and between adjacent outer strands.

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Description

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PLASTIC ENCAPSULATED WIRE ROPE

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Back~round of the Inven~ion The present invention relates to wire rope and, more par-ticularly, to plastic encapsulated wire rope having spacer strands between its central core strand and surrounding outer strands.
Plastic encap~ulated wire rope, such as disclosed in U. S.
Patent No. 3,824,777, has been de~onstrated to have properties such as tensile streng~h, fatigue life and corrosion resi~tance superior to those of equal size bare wire rope. Such improved properties are derived from the separation of the core strand from the outer s trands and the outer s trands fr~m each other by ~he thermoplastic material. Suitable themoplastics include polypropylene, polyurethane, polyethylene, nylon~ tetrafluro-ethylene or polyvinylchloride. Also useful are elastomers such as butyl or nitrile rubber. Such a coating reduces or eliminates such core to strand and strand to s~rand contact and abrasion ~hen the rope i~ in service. Further, the coating traps any de-sired lubricant such as petrolatum within the strands and resists the ingress of abrasive or corrosive elements into the rope.
However, it is desirable to achieve strand gap or interstice balance in the manufacture of such plastic encapsulated wire rope.
Such gap balance insures the equal load sharing by the strands of the rope and also assures the ~pacing between strands is filled with plastic. One method of such gap controL during rope manufacture is set forth in U. S. Patent No. 3,824,777, wherein a strand gap c~ntroller die is utilized to equally ~ `~
separate rope strands during ~he injection of the plastic.

~29 56 ~ nother spacing contro1 method is disclosed in U.K. Pa~ent Application No. 2,090,305 A, wherein a filler element of thermo-plas~ic contalning a rein~orcing core is placed independently in the interstice. The presence o~ such independent the~moplas~ic element would prohibit the introduction of a 1Ow,able thermoplastic into the wire rope.

It is an object o the present invention to provide an encapsulated wire rope having improved strand gaps and a method of making such rope.

0 The present disclosure relates to a wire rope having uniform strand separation and interstices and to a met~od of ~a~ing such rope, The rope Ls comprised of a central core usually comprising ~trands for~ing an independent wire rope core (IWRC). Such rope core i~ surrounded by a plurality of outer strands, each comprised of a plurality o~ individual wires. As such outer strands are wound around the core, there are gaps or spaces or interstices between such outer strands and the core. As the O diameters of the core strand and the outer strands are normally within 25% oE each other, those gaps are sm~ll. However, it is important for the wear li~e and other similar properties of the rope that such gaps are as ~niform as possibLe. This lnsures that during ~he extrusion of the coating ~aterial within the rope that such coating provides a uni~orm spaclng between the core strand and the outer strands and between adjacent outer strands. Accordingly, a spacer strand is placed in each such gap during the closing or rope forming operation. Such spacer strand can take dlfferent forms as will be la~er explained, but the main function of such spacer strand i6 to insure the uniform gap foemation between ~he outer strand~. Further, the ~pacer strand must be of ~uch a configuration ~o a~ to permit the impregnation of the rope after final closing by a coating material such as a thermopla6tic or an elastomer in an extrusion operation.
To permit the coating to be extruded into the spaces between the core strand and the outer strand, the spacer strands must provide gap6 or some other type of passage ~or the coating material. To insure the uniformity of ~he spaces between the outer strands, each spacer strand contacts both the core strand and two outer strands. Another way of viewing the preferred arrangement is that each outer strand contacts two spacer strands to assure the positioning and spacing of the out~r strand. The spacer strands may take any one of several configurations. A
single wire may be wound into a helix arrangemen~ to provide the nece~sary spacing and coating flow figuration. A single central wire can be surrounded by either one or two helixed wires to again provide the necessary spacing and coating flow configuration.
Further, two or three wire6 may be helically wound to form a rope StLuctUre which will provide ~he neces6ary 6pacing and coa~ing flow configuration.
In accordance with one aspect of the pre6ent invention there is provided a wire rope compri6ing:
a central core including a plurality of wire strand~, a plurality of outer strands ~urrounding said core, a plurality of spacer ~trand6 located in the interstice~

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between said core and 6aid outer ~trand , said ~pacer strand6 leaving pas6ageway~ to permit flow of a coating material therethrough, and a coating extending from substantially the outer diameter of the ou~er strand~ down to and into the central core.
In accordance with a second aspect of the invention there is provided, a wire rope comprising:
a centcal core of wire ~trand6, a plurality of outer strands surrounding 6aid core, a plurality of 6pacer strands located in the inter6tice~
between 6aid core and 6aid outer 6trands each spacer strand contacts the outer surface of the central core and two outer strand6, and a coating extending from sub6tantially the outer diameter of the outer strand6 down to and into the central core.
In accordance with a third aspect of the invention there i~
provided, a wire rope comprising:
a central coLe strand, a plurality of intermediate 6trands surrounding said core strand, and a plurality of outeL ~trands ~urrounding said intermediate strands, 6pacer strands located in the inter6tices between said core strand and 6aid intermediate strand~ and in the interstices between the intermediate strand6 and the ou~er strands, and a coating extending from 6ubstantially the outer . diameter of 6aid outer s~rand6 down to and into ~aid core Rtrand.

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In accordance with a fourth aspect of the invention, there is provided a method of manufacturing a wire rope compri~ing the steps of providing a central core strand, winding a plurality of spacer 6trands about said core strand, winding a plurality of outer 6trands about said ~pacer strand6 and said core strand so as to form evenly dimen6ioned interstice~ between said core strand and said outer strand6 containing said 6pacer strand6~
and injecting a coating into said wire rope so a~ to form a continuous, single element compo~ition between the central core and the outer ~trands and between the outer strands.
With a rope here described it is po6~ible to maintain a serie6 of strand to strand gaps of even dimen~ion which permits the ingres6 of plastic between the strands through the pas6ageway6 in the spacer element into the core. The equal 6trand gaps permit a continuous coating of plastic to be formed ~o provide a po6itive bond for the external infilling to the underlaying infilling, thereby preventing the detachment of the external infilling under arduous operating condition6 during the æeriods of continual flexing around smaller than desirable sheave6 or drum6.
Specific embodiment6 of the invention will now be de~cribed with reference to the accompanying drawing6 wherein, Figure 1 is a cross zectional view o~ an encapsulated wire rope embodying the pre~ent inven~ion:
Figure Z is a cros6 sectional view of another encap6ulated - 4a -~- , ' s~

wire Lope embodying the present invention:
Figure 3 i6 a cro6s ~ectional view of another en~apsulated wire rope embodying the pre6ent invention:

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Fi~ure 4 is a perspective view of one embodiment of a spacer strand;
Figure 5 is a perspective view of another embodiment of a spacer strand;
Figure 6 is a perspective view of another embodiment of a spacer strand, and Figure 7 is a perspective view of another embodiment of a spacer strand De~cription of the Preerred Embodiment Referring now to Figure 1 of the drawings, a wire rop~ is shown generally at 10. A central core strand 14 comprises several single wires lS in a wire rope configuration. Core 14 is surrounded by a plurality of outer-strands 12, each of which is comprised of sP-veral single wires 13 in a wire rope configura-tion. Spacer strands 16 are present in the interstices between core 14 and outer strands 12. Spacer strands 16 are shown as comprising three wires wound to orm a strand. A coating 18 extends from the outer surface of core 14 to the outer diameter limits of outer strands 12. Each spacer strand 16 contacts core 14 and two ~u~er strands 12. Coating 18 usually comprises a thermoplastic, and separate core stra~d 14 from outer strands 12, as well as outer strands 12 fro~ adjacent outer strands Coating 18 is uniform and, due ~o its extruded introduction into rope 10, forms a continuous ~ingle element com~osition~
Referring now ~o Figure 2 of the drawings, a wire rope is shown generally at 20. A central core strand 22 is provided and is comprised of a plurality of individual wires 23 in a wire Case 5875 .ope configuration. Surrounding core strand 22 are a plurality of inte~mediate strands 24, each of which is comprised of a plurality of indiv~duaL wires 25. Spacer strands 26 are located in the interstices between core strand 22 and intermediace strands 24, and spacer strands 9 are located in the interstices between intermediate strands 24 and outer strands 28. Spacer strands 26 and 9 are shown as comprising three wires wound to form a strand.
A plurality of outer strands 28 surround intermediate strands 24.
Each outer strand 28 is comprised of a plurality of individual o wires 29. A coating 30 e~tends f~om the outer surface of core 22 to the outer diameter limits of outer ~trands 28. Each spacer strand 26 contacts core 22 and two intermediate strands 241 and each spacer strand 9 contacts an intermediate strand 24 and an outer strand 28. Coating 30 usually comprises a thermoplastic 9 and separates core strand 22 from intexmediate strands 24, inter-mediate strar.ds 24 from outer strands 28, intermediate strands 24 from adjacenl: intPrmediate s~xands and outer strands 28 from adjacent outer s~rands. Coating 30 is uniform and, due to its extruded introduction into rope 20, forms a continuous, single 20 element composition.
Referring now to Figure 3, a wire rope is shown generally at 32 . A central core s trand 34 i9 provided and is comprised o a plurality of individual wires 33. Surrounding core strand 34 are a plurality of intermediate strands 36, each o which is com-prised of a plurality of individual wires 35. In the interstices between core strand 34 and intermediate strands 36 are located spacer strands 38. Spacer strands 38 are shown as comprising two wire~ wount to form a strand. A coating 40 extends from the outer surface of core 34 to the outer diameter limi~s of inter-mediate strands 36. Each spacer strand 38 contacts core 34 and two intermediate strands 36. Coa~ing 40 usually comprises a -6~

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thcrmc~].~Y~iC~ and separates core strand 34 from intermediate strands 36 and core strands 34 from adjacent core strands and intermediate strands 36 ~rom adjacent intermediate strands.
Coating 40 is uniform and, due to its extruded introduction into the rope comprising core strand 34 and intermediate strands 36, forms a continuous, single element compositionO A plurality of outer ~trands 42 each comprising individual wires 39 surround the coated intermediate strands 36, Referring now to Figures 4-7, various embodiments of the spacer strands of the present invention are shown. Normally such spacer strands are of a softer me~al than the strands that they separate to avoid notching of the core or outer strands that they separate. In Figure 4, a spacer strand is shown com-pri-ing two individual wires 44 and 46 which are helically wound about each other to form the spacer strand. It is also an embodiment of the prese~t invention to helically wind three wires about each other to form a spacer strand; such an arrange-ment i9 shown in cross section in Figures 1 and 2.
In Figure 5, a spacer strand is shown comprising a single 20 wire 48 that is wound into a heli~ about an imaginary central axis.
In Figure 6, a spacer strand is shown comprising a center wire 50 about which is wound an outer wire 52.
In Figure 7, a spacer strand is shown comprising a center wire 54 about which are wound outer wires 56 and 58 in alter-nating heli~ arrangement.

Claims (20)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A wire rope comprising:
a central core including a plurality of wire strands, a plurality of outer strands surrounding said core, a plurality of spacer strands located in the interstice between said core and said outer strands, said spacer strands leaving passageways to permit flow of a coating material therethrough, and a coating extending from substantially the outer diameter of the outer strands down to and into the central core.
In accordance with a second aspect of the invention there is provided, a wire rope comprising:
a central core of wire strands, a plurality of outer strands surrounding said core, a plurality of spacer strands located in the interstices between said core and said outer strand each spacer strand contacts the outer surface of the central core and two outer strands, and a coating extending from substantially the outer diameter of the outer strands down to and into the central core.

2. A wire rope comprising:
a central core of wire strands, a plurality of outer strands surrounding said core, a plurality of spacer strands located in the interstices between said core and said outer strands each spacer strand contacts the outer surface of the central core and two outer strands, and a coating extending from substantially the outer diameter of the outer strands down to and into the central core.

3. The wire rope of claim 1, wherein each spacer strand comprises two separate wires helically wound about each other.

4. The wire rope of claim 1, wherein each spacer strand comprises three separate wires helically wound about each other.

5. The wire rope of claim 1, wherein the spacer strand comprises a single wire coiled in a spring like configuration.

6. The wire rope of claim 1, wherein the spacer strand comprises a central wire having a second wire helically wound about it.

7. The wire rope of claim 1, wherein the spacer strand comprises a central wire having two wires wound helically about it.

8. The wire rope of claim 1, wherein the spacer strand is comprised of a softer wire than the core strand and the outer strands.

9. The wire rope of claim 1, wherein the coating is a thermoplastic.

10. The wire rope of claim 1, wherein the coating is an elastomer.

11. The wire rope of claim 1, wherein the coating is of a continuous, single element composition.

12. A wire rope comprising:
a central core strand, a plurality of intermediate strands surrounding said core strand, and a plurality of outer strands surrounding said intermediate strands, spacer strands located in the interstices between said core strand and said intermediate strands and in the interstices between the intermediate strands and the outer strands, and a coating extending from substantially the outer diameter of said outer strands down to and into said core strand.

13. The wire rope of claim 12, wherein the coating is a thermoplastic.

14. The wire rope of claim 12, wherein the coating is an elastomer.

15. The wire rope of claim 12, wherein the coating is of a continuous, single element composition.

16. The wire rope of claim 12, wherein each of said spacer strands is of a configuration forming passageways to as to permit the flow of the coating therethrough.

17. A method of manufacturing a wire rope comprising the steps of providing a central core strand, winding a plurality of spacer strands about said core strand, winding a plurality of outer strands about said spacer strands and said core strand so as to form evenly dimensioned interstices between said core strand and said outer strands containing said spacer strands, and injecting a coating into said wire rope so as to form a continuous, single element composition between the central core and the outer strands and between the outer strands.

18. The method of claim 17, wherein the coating is a thermoplastic.

19. The method of claim 17, wherein the coating is an elastomer.

20. The method of claim 17, wherein the coating during injection passes through said spacer strands due to their configuration.