US3209528A

US3209528A - Flexible wire rope core

Info

Publication number: US3209528A
Application number: US276009A
Authority: US
Inventors: Charles M Zerr
Original assignee: Armco Inc
Current assignee: Armco Inc
Priority date: 1963-04-26
Filing date: 1963-04-26
Publication date: 1965-10-05
Anticipated expiration: 1982-10-05

Description

Oct. 5, 1965 c. M. ZERR FLEXIBLE WIRE ROPE CORE Filed April 26, 1963 5 Sheets-Sheet l R I mm N E Z WM 8 C.- l- 2 A H C ATTORNEY.

Oct. 5, 1965 c. M. ZERR 3,209,528

FLEXIBLE wmm non". coRE Filed April 26, 1963 v s ShBetS- -Sheet 2' mvsmon CHARLES M. Z522,

ATTORNEYS.

Oct. 5, 1965 c. M. ZERR FLEXIBLE WIRE ROPE CORE 3 Sheets-Sheet 3 Filed April 26, 1963 IINVENTOR. CHARLES M. Zena,

[hr-l Anbnuevs.

3,209,522; FLEXIBLE WIRE ROPE COR Charles M. Zerr, Independence, Mo.,-;assignor to Armco Steel Corporation, Middletown, Ohio, a corporation of Ohio v v .zlFiled Apr. 26, 1963, Set. No. 276,009

, Claims. ((157-145) This invention relates to a flexible wire rope core.

In wire rope such as is used in connection-with hoists, derricks, cranes, and similar hoisting-equipment and also in earth moving equipment such as drag lines and for a great variety of purposes, it is conventional practice to provide a core for the wire rope or cable, which core is in itself made up of one or more wires. The present invention relates to the construction of the core itself and not particularly to the wire rope as a whole.v

It is a principal object of the invention to provide a wirerope core which is considerably more flexible than wire rope cores us'ed heretofore, whereby to provide for greater resistance to fatigue breaking. It is another object of the invention to provide a wire rope core which will be firm enough so that it will not distort, collapse or break and thereby contribute to the failure of the wire rope as a whole.

A still further object of the invention is to provide a wire rope core having the above outlined advantageous characteristics which is capable of being closed in a single operation.

These and other objects of the invention which will be described in greater detail hereinafter or which will be apparent to one skilled in the art upon reading these specifications, are accomplished by that construction and arrangement of parts of which several embodiments will be described hereinafter.

Reference is made to the drawings forming a part hereof and in which:

FIG. 1 is a diagrammatic cross-sectional view through a wire rope and a core according to the present invention.

FIG. 2 is a view similar to FIG. 1 but of a modification.

FIG. 3 is a view similar to FIG. 1, but of a modification.

Briefly, in the practice of the invention there is provided a core which is composed of three elements. There is a central element which is preferably a multi-wire strand; around this there is an intermediate layer of eight wires or strands and around the intermediate layer is a covering layer of eight multi-wire strands. In small wire rope, say up to about 2% inches in diameter, the intermediate layer is preferably constituted of eight solid wires. Where the wire rope is of an outside diameter of 2% inches and up, the intermediate layer may be composed of multi-wire strands, as, for example, seven wire strands.

A wire rope core must be a compromise between two apparently mutually inconsistent qualities. First, it must be flexible enough so as to resist breaking as a result of fatigue either from impact or bending. Secondly, it has to be firm enough so that it will not collapse or break and contribute to the ultimate failure of the wire rope. The reason that these qualities are apparently mutually inconsistent is that optimum flexibility requires a multiplicity of strands or wires and of course the more strands or wires used, the smaller the diameter of the wires or strands will be. Generally speaking, however,'the smaller wires or strands are more likely to break than heavier wires or strands. On the other hand, firmness of the core suggests a minimum number of strands of relatively heavier wire. Such a strand will be much less flexible.

The present invention solves the above outlined dilemma by a particular arrangement of wires and strands in the core and gives a core which provides better support for the main strands of the wire rope which is, at the same time more flexible than conventional wire rope cores,

and' which provides an increased metallicarea for the total rope cross-section. v

Referring now more particularly to FIG. 1 and FIG. 3,

the core is that portion in the center of the figure within the circle 10. The central element of this core may be a seven wire strand, as shown in FIG. 1, having the formula (1-6). This means that there is a central'wire 11 surrounded by six wires 12. It may also be a nine wire strand as shown in FIG. 3, having the formula (l-8). This means that there is a central wire 11a surrounded by eight wires 12a. ,1

Around this central strand is an intermediate layer comprising eight solid wires 13 and around the intermediate layer is a covering layer of eight seven wire strands, each comprising a central wire 14 surrounded by six wires 15.. Thus the strands in the covering layer again have the formula (L6). The formula for the core may thus be expressed as follows:

Comparing a standard 7 by 7 core with the core of the I present invention, is should be noted that there is an additional strand in the intermediate layer composed of the strands 13, and an additional strand in the covering layer composed of the strands 14-15. These two additional strands give added support to the outer strands of the rope.

The construction of the present invention, and the additional strands, also make the core considerably more flexible than the standard 7 by 7 core now in general use.

This results from the fact that the core is made up of more wires and more strands, laid in the same direction, rather than cross laid.

There have been special cores, some of which have been patented, which are made up in what is known as a two operation construction. Such cores are madev in such a manner that the various elements are cross laid. When the elements are cross laid, areas of stress concentration are set up, and these cause fatigue failures of the wires at points of intersection. nates cross-laying of'wires and thus overcomes the problem just described. The resulting wire rope has a greater strength for a given size and is much more flexible. There is also obtained the added advantage that the core may be made up in one operation.

Cores such as those described above in connection with FIG. 1 are excellent in wire rope up to about 2% inch outside diameter. In a larger diameter wire rope it may be desirable to substitute for the eight single wire elements of the intermediate layer eight seven wire strands having the formula (I6) and the covering layer strands, instead of being seven wire strands, may be provided in the form of nineteen wire strands No matter what the composition of the strands, the core may still be closed or assembled in a single operation.

In FIG. 2 a typical wire rope of large diameter is shown wherein the central element 11a is a seven wire (1 x 6) strand and where the intermediate layer comprises eight seven wire strands having the formula (l-6) The present invention elimiand indicated generally at 130 and wherein the strands of the covering layer indicated generally by the circles 14a are nineteen wire strands of any desirable formula. By comparing a core according to the present invention with conventional independent wire rope core, it will be found that the cross-sectional area of steel in the present core will be 6% to 10% greater, and it has been found that a core according to the present invention has, due

' to design and fabrication, about 115% greater tensile strength than a conventional core.

A core according to the present invention is also considerably more flexible than a conventional core. A

flexibility test generally used comprises leading the wire rope in a sinuous path over pulleys and running it back and forth in a sinuous path. A core according to the present invention will gofrom 20% to 30% more cycles than a conventional core.

A reduction in the tendency of they core to collapse and be crushed by the radially inward pressure of the wire rope strands is shown by the fact that the ropes will not show what is known as adjacent strand notching" but will wear on the outside of the rope where the wear should take place and where the wear can be observed.

Adjacent strand notching" is not so readily apparent upon inspection but nevertheless weakens the rope and this problem is substantially eliminated with a-core according to the present invention.

It-will be clear that various modifications may be made 1. A wire rope core comprising a central multi-wire,

strand. and intermediatelayer comprising eight elements closed aroundsaid central strand, and a covering layer of eight multi-wire strands closed around said intermediate layer, said intermediate and covering'layers being closed around said central strand simultaneously, where-- by the strands of the covering layer nestle in the valleys between the strands of the intermediate layer for maximum support.

2. A wire rope core according to claim 1, wherein said central multi-w-ire strand has a central wire surrounded by six wires.

3. A wire rope core according to claim 1, wherein said central multi-wire strand has a central wire surrounded by eight wires.

4. A wire rope core according to claim 1 wherein said eight elements of intermediate layer are solid wires.

5. A wire rope core according to claim 1, wherein each of the multi-wire strands of said covering layer has a central wire surrounded by six wires.

6. A wire rope core according to claim 1 wherein said central strand has a central wire surrounded by six wires, said intermediate layer consists of eight single wires, and said covering layer consists of eight strands, each having a central wire surrounded by six wires.

7. A wire rope core according to claim 1 wherein said central strand has a central wire surrounded by eight wires, said intermediate layer consists of eight single wires, and said covering layer consists of eight strands,

each having a central wire surrounded by six wires.

8. A wire rope core according to claim 1 for wire rope of large diameter, wherein each of said eight elements of the intermediate layer has a central wire surrounded; by SIX wires.

9. A wire rope core according to claim 1 for wire rope of large diameter, wherein each of the eight multiwire strands of said covering layer comprises-a nineteen wire strand.

10. A wire core according to claim 1 for wire rope of large diameter, wherein each of said eight elements of the intermediate layer has a central wire surrounded by six wires and each of the eight multi-wire strands of said covering layer comprises anineteen wire strand.

References Cited by the Examiner UNITED STATES PATENTS I MERVIN STEIN, Primary Examiner.

Claims

1. A WIRE ROPE CORE COMPRISING A CNTRAL MULTI-WIRE STRAND, AND INTERMEDIATE LAYER COMPRISING EIGHT ELEMENTS CLOSED AROUND SAID CENTRAL STRAND, AND A COVERING LAYER OF EIGHT MULTI-WIRE STRANDS CLOSED AROUND SAID INTERMEDIATE LAYER, SAID INTERMEDIATE AND COVERING LAYERS BEING CLOSED AROUND SAID CENTRAL STRAND SIMUTLANEOUSLY, WHEREBY THE STRANDS OF THE COVERING LAYER NESTLE IN THE VALLEYS BETWEEN THE STRANDS OF THE INTERMEDIATE LAYER FOR MAXIMUM SUPPORT.