US1777117A - Wire rope and method of making the same - Google Patents

Description

p 30, 1930- R. D. GREEN 1,777,117

WIRE ROPE AND METHOD OF MAKING THE SAID Filed Feb. 26, 1929 wmgpm Egon/"boa Patented Sept. 30, 1930 UNITED STATES PATENT OFFICE RICHARD DUANE GREEN, OF TRENTON, NEW JERSEY, ASSIGNOR TO JOHN A. ROE- BLINGS SONS COMPANY, OF TRENTON, NEW JERSEY, A CORPORATION OF NEW JERSEY WIRE ROPE. AND METHOD OF MAKING THE SAME Application filed February26, 1929. Serial No. 342,765.

This invention relates to wire rope and to methods for constructing the same, the especlal ob ect of the invention being to provide an improved wire rope adapted for generalv operating service.

Operating service conditions to which wire rope may be subjected have been found to vary greatly. I For example, arope sometimes must operate at slow speed, under extremely high tension while bending over sheaves and drums of large diameter. Or thespeed may be extremely high, the tension may be moderate or low, and the sheaves or drums may have small or medium diameters and these conditions are capable of many combinations. Since, from a practical standpoint, it would be impossible to provide separate ropes for each possible operating condition, the rope itself when placed in service must readjust its manufactured condition to fit its operating condition.

In the manufacture of the ordinary stranded wire rope, a plurality of substantially straight wires are laid up helically on a central core to form a strand and then the finished rope is roduced by laying a plurality of these su stantially straight strands helically around a central core. The rope so formed is capable of accommodating itself readily to various operating or service conditions. This can readily be seen when it is considered that in such standard ropes the wires in the strands and the strands in the ropes are not formed to definite helices so that the wires and strands readjust themselves, that is, assume proper relative positions for equalizing stresses and strains.

Rope manufactured according to this standard method has the disadvantage that inequalities in the wire tensions or strand tensions when closed into rope, or inequalities in size and hardness of the center, though not occurring together at any given section, tend to concentrate at one point during the course of readjustment. Such inequalities have been found to travel a considerable length of rope and concentrate at the same point with the result that rapid deterioration with consequent short rope life takes place, which would not occur if these inequalities were distributed throughout the rope.

A second method of manufacture has been employed, that of the helically formed wire and strand. With this method the individual wires of the strands are formed into helices and then laid about the core to form straight strands, after which the straight strands themselves are formed helically and then laid about a core to form the finished rope. In some cases, the wires and strands are formed to a helix having a slightly smaller diameter than the diameter of the core so that the wires in the strands and the strands in the rope have a tendency to hug the core.

With this construction, travel of inequalities from one section to another is prevented,

but readjustment to operating conditions, also, is prevented, so that such a rope does not secure maximum service under various operating conditions.

In accordance with the method of the present invention, a wire rope is provided which has the advantage of adjusting itself to operating conditions but which shall avoid the disadvantage of permitting inequalities to travel along its length and concentrate at certain points. This result is secured in accordance with the present invention, by the provision of a rope made up of alternate sections of standard type rope and rope made up by the method of forming the wires and strands, or in some cases the strands only, into helices before laying them into the strand or rope. The length of the different sections may be varied as desired, and the formed sections may be quite short relatively tothe standard sections for ropes of some types and for some purposes, and the reverse for other types or other purposes.

The drawing illustrates a preferred form of embodiment of the invention, for rope in which the readjustment for different operating conditions and prevention of the concentration of inequalities are desired, in which drawing:

Figure 1 is an outside view of a piece of wire rope, and

Figure 2 is a cross section thereof.

In the drawing, the rope I is made up of a plurality of strands 2 surrounding a central core 3 and each of these strands is composed of a plurality of individual wires 4 laid upon a central core 5. The rope 1 as shown is made up of a number of sections. The sections 6 are made in accordance with the standard construction, that is, each strand 2 is made by laying the wires 4 about the core 5 without previously forming them into helices and then laying the straight strands about the core 3 without attempting to control the wire or strand shape. The strands of section 7 are manufactured by formin the wires into a definite helix and then laylng them about the core and the section 7 itself is made by forming the strands into a definite helix and then laying them about the core 3. These sections 6 and 7 may be alternated throughout a rope length, and may be of various lengths relatively to each other, depending on the type of rope desired. In this way there is produced a rope made up of a plurality of formed, and unformed sections, and for general uses the formed sections may be quite short and the standard sections be quite long so that the rope is chiefly of standard construction.

With a rope so constructed it has been found that those sections of standard construction permit readjustment of wires in the strands and of strands in the rope to compensate for various operating conditions, while the sections in which the wires and strands are formed into helices before laying prevent the traveling of any inequalities between adjacent standard sections, with the result that concentration of inequalities in the rope is prevented or limited to short sections of the standard rope.

It has been found that, by varying the relative length of formed and standard sections the all-round serviceability of the rope may be greatly improved, and that, where a standard rope is better suited for one operating condition and a formed rope for another operating condition, a rope constructed in accordance with this invention is well suited for both conditions.

A rope constructed in accordance with the foregoing method may be employed to advantage for elevator cables where it is important that a break in any of the wires or strands be immediately noticed upon an inspection of the cable. .When standard wire rope is used for elevator cable and a break in the wire or strand occurs, the broken ends of the wire or strand spring away from the body of the rope'and stand out noticeably. With a rope made throughout its length-with the wires and strands given a definite set by forming them into helices before laying, there is no tendency of broken ends to spring out, with the result that detection of breaks is difiicult. The composite rope of the present invention havlng alternate standard and formed sections is'well adapted for elevator work, as most of the rope may be made with the wires and strands having a definite helical set and no tendency to spring out, while the standard sections serve as tell tales to indicate breaks by the wires springing out.

In some cases, it may not be necessa or desirable to form the individual wires 0 the strands in sections or at all previously to laying them up in the strands, but the results desired may be secured by forming only the strands before they are laid up in the rope. In the case of 19-wire strands, the forming of the strands in sections, before laying them up into the rope, results in the forming of the outside wires of the strands sufficiently to secure the desired results, but, in a rope containing 37 wires per strand, or more, it is found that for most purposes it is advlsable to form both the wires before laying them up in the strands and the strands before laying them up in the rope.

The method of the present invention is applicable for many purposes as, for instance by using formed sections where the strand or rope is to be cut for socketing or other purposes, the cutting and socketlng may be used without losing any twist at the socketed ends. The invention is useful, also, in connection with cables which must not stretchexcessive- 1y, as for instance in main cables for suspension bridges, by permitting the advantages of wires and strands formed before laying them up to be secured, while avoding the excessive stretch resulting from using such formed wires or strands throughout the full length of the strand or rope.

While the invention has been illustrated 1n a construction embodying all its features in a form now preferred, it will be understood that the invention is not limited to the specific construction or arrangement shown but that modifications may be made by those skilled 1n the art while retaining the invention defined by the claims.

What is claimed is:

1. The method of making wire rope which comprises formin the wires into helices and laying into stran s, forming the strands mto helices and layin into rope for a portion of the rope, and t en laying the wlres into strands and the strands into rope throughout the next portion of the rope without forming the wires and strands into helices before la 'ng.

2. Thb method of making wire rope which comprises formin the wires into helices and laying into stran s, forming the strands into helices and la ing into rope for a sectlon 0f the rope, an then laying the wires into strands and the strands into rope to form the next section of the rope without forming the wires and the strands into helices before laying, said sections being alternated throug out the length of the rope.

3. The method of making wire rope which comprises forming the strands into helices and laying into rope for a portion of the rope, and then laying the strands into rope throughout the next portion of the rope without forming the strands into helices before laying.

4. The method of making wire rope which comprises forming the strands into helices and laying into rope for a section of the rope, and then laying the strands into rope to form the next section of the rope without forming the strands into helices before laying, said sections being alternated throughout the length of the rope.

5. A continuous strand wire rope of which a portion comprises wires and strands formed into helices before laying them into the strand'or rope, and the next portion having its wires and strands not formed into helices before laying.

6. A continuous strand wire rope construction comprising alternate sections, one of said sections I comprising wires and formed into helices before laying into the strand or rope, and the next section having its wires and strands not formed into'helices before laying.

7. A continuous strand wire rope having a portion comprising strands formed into helices before laying them into the ro e and the next portion having its stran s not formed into helices before laying.

8. A continuous strand wire rope construction comprising alternate sections, one of said sections comprising strands formed into helices before laying into the rope, and the next section having itsv strandsnot formed into helices before laying.

In testimony whereof, I 'have hereunto set my hand.

RICHARD DUANE GREEN.

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