US3130536A - Method of manufacturing wire rope - Google Patents

Description

April 28, 1964 v. c. J. PETERSON ETAL 3,130,536

METHOD OF MANUFACTURING WIRE ROPE Filed Sept. 21, 1961 United States Patent METHOD OF MANUFACTURlNG WEE RGPE Vincent C. J. Peterson, Huntingdon Valley, Pa., Otto J.

Bratz, Adrian, Mich, and Charles H. Layton, Forty Fort, Pa., assigncrs to American Chain 8; Cable Co.

Inc., New York, N.Y., a corporation of New York Filed Sept. 21, 1961, Ser. No. 139,675 7 Claims. (Cl. 57-161) This invention relates to wire rope, and, in particular, to the development of a greater efficiency in such rope than has previously been possible.

In the sense used here, wire rope is a plurality of strands of wire laid around a central core. The invention is also possible to apply to that type of wire line, sometime called cable, comprising of a plurality of ropes laid around a core, but its advantages in such a situation may not be so obvious.

Wire rope, to be efficient, should theoretically stress each wire, regardless of its diameter and position in the rope, exactly the same. Early in the art, this was achieved by utilizing material which would yield under stress, so thatthose wires overstressed because of imperfect laying or closing could stretch until the understressed wires took up their share of the load. Various other materials have been developed which have a higher strength, but still have great enough yield to permit this equalization of load from wire to wire. For the purpose of further improving the efliciency of wire rope, and for other reasons, preformed rope was developed, in which each individual wire is set in the shape it should have in order to take its share of the load, instead of being forced into that position by adjacent wires. This, incidentally, permits the use of harder and less yielding wires in the construction of the rope, as there is less disparity of stress from wire to Wire. However, the chief advantage of preforming is the increase in resistance to fatigue, and a lessening of'the deleterious effects of having a large portion of the wires under elastic deformation, rather than lying inert in the rope.

In view of the above current state of the art, it is a primary object of the present invention to provide a wire rope of greater efiiciency than that obtained by present commercial practices.

It is a further object of this invention to provide a wire rope with the individual wires thereof as far as possible subjected to the same stress.

It is proposed to produce such a rope by subjecting the strands thereof to cold work before they are laid up into a rope. The form of cold work selected is a series of rapid, comparatively light blows applied with a rotary swager, of a strength and frequency to cause flow and deformation of the metal Wires of which the strand is formed. Thus the Wires, originally of circular cross section, approach polygons in cross section. Strand treated in this fashion differs from strand treated by any other process, such as repeated reverse bending, or drawing the laid strand through dies. Such bending and, to a certain extent, such drawing of strand, does tend to make the wires of the strand inert, and act as if preformed, but these operations, and particularly the latter, tend to loosen up the strand so that the individual wires do not lie snugly against the adjacent wires as they should.

Referring now to the drawings:

FIG. 1 is a cross-section of a strand of which the rope is to be formed after laying;

FIG. 2 is a cross-section of the same strand after swaging; and

FIG. 3 is a section of a series of these strands closed into a rope.

Although the treatment to be described is applicable to many rope constructions, the construction shown is taken as typical, and as illustrative of certain of the problems encountered, to some extent, in most constructions. The strand shown is considered as nineteen wires plus six filler wires. The arrangement is a strand of six wires around a center wire, and twelve wires around the six, to form a nineteen wire strand. The six filler wires are utilized between the six wires series and the outer circle of twelve in such a fashion that the outer twelve are circularly arranged and lie snugly against the array of six filler wires and six main wires. Despite this separate description of the ring of six and the ring of twelve wires, all wires are laid around the center wire at once, and their relative positions remain throughout the structure.

In normal construction of strand, the size of the center Wire 1% and that of the six wires 11 therearound are set by geometry. Six circles of equal diameter can be drawn tangent to a seventh circle and tangent to each other. Because of the lay of the wires, however, the six wires 11 are slightly smaller than the core wire it), the true section of wires 11 in FIG. 1 being very slightly elliptical rather than circular. The size of the filler wires13, and that of the circle ofwires 12 are assigned by the same considerations.

If such a structure is subjected to an intermittent radial hammering action, the internal wires 10 and 11 will take on a polygonal cross-section, as shown in FIG. 2, the center wire it approaching a hexagon, the filler wires approximating squares or rhombi, theother wires 11 and 12 taking irregular but symmetrical shapes. The type of hammering contemplated is with a rotary swager, which gives a large number of quick, light blows spaced around the periphery of the strand as the strand is fed through the swager. Such hammering causes the impactment of the wires against each other and the deformation shown in FIG. 2.

It has been found that if the swaging operation is carefully limited, an increase in fatigue resistance and efficiency can be expected. Swaging for this object has been found to have its limits, the beneficial effects of swaging increasing as the swaging proceeds up to, in the case of the construction shown, the point where the swaged surfaces of the outer wires is equal in extent to the space between each of them. That is to say, dimension a should be approximately equal to dimension b in FIG. 2. For other constructions, this figure may be different,

but fatigue and strength tests in general indicate that the optimum swaging is about as indictaed above. Starting with wire intended for fabrication into strand for rope without swaging the above holds true for the various grades of steel used today.

One reason for selecting a filler wire construction as an illustration is that thefiller wires 13 are of considerably less diameter than the wires adjacent them. Under swaging, such filler wires suffer the greatest deformation, their outer surfaces becoming slightly concave, because of the presence of the larger wires surrounding each filler wire. As any deformation by radial compression results in some elongation, it is to be expected that thewires 13 will elongate to a greater extent than those adjacent thereto. T he result would be for these wires to be under a state of longitudinal compression, which means, of course, that they do not carry their full share of the load. In fact, the elastic compression may be so great that the defonnation of the strand as it is closed around the core causes it to pop out between the adjacentouter wires 12.

The remedy for this situation is to utilize a wire at 13 which is smaller than normally used in this position for strand not to be swaged. It therefore deforms and elongates as before, but not to such a great extent, and samples tested show thewires 13 in the same state, so far 3 as tension and compression is concerned, and with no tendency to leave their assigned position as the strands are closed around the core.

The swaged strands are shown closed around a core in FIG. 3. The particular core selected for illustration is a small rope. The large amount of space between therope 15 and the strands is more apparent than real, as the number of turns per foot of the inner rope strands 16 is different from that of theswaged strands 17. As a result, the inner or center rope can be described as independent of therope strands 17, and, actually, it takes its share of the load exactly as the rope strands do.

In addition to the advantages aimed at, the production of a rope of the highest efficiency attainable, other advantages appear. Because the outer surface of each strand is smoother than is the case when the crown wires are round, the rope offers considerably more resistance to abrasion, and itself does not abrade pulleys, fairleads or hooks, or rings along which it may be required to pass.

A result which is particularly important is the decrease in strand nicking. Where the wires of adjacent strands touch each other, in the valleys of the rope, they cross at an angle. Under load, which compresses the core, adjacent crown wires nick each other, resulting in high stress concentration decreasing the fatigue resistance of the rope. Theswaged crown wires 12 of one strand cross the wires of an adjacent strand, but, because the surfaces of the crown wires in contact are much flatter, because of the swaging, the nicking is much less severe, which possibly is one cause of the increased fatigue resistance of the rope.

We claim:

1. A method of manufacturing wire rope which comprises forrning wires into a plurality of strands, subjecting each of said strands to a multiplicity of intermittent radial swaging blows about its circumference without imposing substantial axial tensile stress on any of the wires thereof, whereby the exposed surfaces of the outer wires of each strand are substantially flattened and the inner wires thereof are deformed in cross section to close substantially all of the voids among the wires without substantially elongating any of said Wires, and helically wrapping said strands about a core to form a wire rope.

2. A method according to claim 1 wherein the substantially flattened exposed surface of each outer wire has a radius of curvature centered on the axis of its respective swaged strand, and the aggregate of these substantially flattened surfaces on each strand comprises substantially one-half the periphery of the strand.

3. A method of manufacturing wire rope which comprises forming round wires into a plurality of strands of snbstantially circular cross section, subjecting each of said strands to a multiplicity of intermittent radial swagingblows about its circumference and throughout its length without imposing substantial axial tensile strength on any of the wires thereof, whereby the exposed surfaces of the outer wires of each strand are substantially flattened and the inner wires thereof are deformed in cross section to close substantially all of the voids among the wires without substantially elongating any of said wires, and helically wrapping said strands about a core to form a Wire rope.

4. A method according to claim 3 wherein the substantially flattened exposed surface of each outer wire has a radius of curvature centered on the axis of its respective swaged strand, and the aggregate of these substantially flattened surfaces on each strand comprises substantially one-half of the periphery of the strand.

5. A method according to claim 3 wherein the core about which the strands are wrapped is itself of stranded wire construction.

6. A method according to claim 5 wherein certain of the outer stranded wires of said core cross at an angle against certain of the outer wires of the strands wrapped about the core.

7. A method of manufacturing wire rope which comprises forming round wires of relatively larger and relatively smaller diameters into a plurality of strands of substantially circular cross section, each smaller wire being disposed in a cross sectional space greater than its own cross sectional area, subjecting each of said strands to a multiplicity of intermittent radial swaging blows about its circumference and throughout its length without imposing substantial axial tensile stress on any of the wires thereof, whereby the-exposed surfaces of the outer wires of each strand are substantially flattened and the inner wires thereof are deformed in cross section to close substantially all of the voids among the wires without substantially elongating any of said wires, and helically wrap ping said strands about a core to form a wire rope.

References Cited in the file of this patent UNITED STATES PATENTS 1,990,514 Angell Feb. 12, 1935 2,156,652 Harris May 2, 1939 2,399,419 Wright Apr. 30, 1946 2,978,860 Campbell Apr. 11, 1961 3,083,817 Campbell Apr. 2, 1963 FOREIGN PATENTS 14,121 Great Britain of 1892 794,412 Great Britain May 7, 1958

Claims (1)

1. A METHOD OF MANUFACTURING WIRE ROPE WHICH COMPRISES FORMING WIRES INTO A PLURALITY OF STRANDS, SUBJECTING EACH OF SAID STRANDS TO A MULTIPLICITY OF INTERMITTENT RADIAL SWAGING BLOWS ABOUT ITS CIRCUMFERENCE WITHOUT IMPOSING SUBSTANTIAL AXIAL TENSILE STRESS ON ANY OF THE WIRES THEREOF, WHEREBY THE EXPOSED SURFACES OF THE OUTER WIRES OF EACH STRAND ARE SUBSTANTIALLY FLATTENED AND THE INNER WIRES THEREOF ARE DEFORMED IN CROSS SECTION TO CLOSE SUBSTANTIALLY ALL OF THE VOIDS AMONG THE WIRES WITHOUT SUBSTANTIALLY ELONGATING ANY OF SAID WIRES, AND HELICALLY WRAPPING SAID STRANDS ABOUT A CORE TO FORM A WIRE ROPE.

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