US2061483A - Rope - Google Patents

Description

Nov. 17, 1936. sA A. REED ROPE Filed June l5, 1935 Patented Nov. 17, 1936 Plymouth Cordage C ompany, North Plymouth,

Mass., acorporation of Massachusetts Application June 15,

11 Claims.

This invention relatesto improvements in rope. More 'particularly it provides forprolonging the serviceable Ilife of cable-laid rope made Aof hard vegetable libre, in which hitherto, under certain r conditions -of use of the rope in well drilling and the`like, internal abrasion has made the rope fail 3before 'the surface 'elements were worn away enough to bring the life of the rope to a normal end. 10 Rope of the general type to which the invention relates is also sometimes in the trade called '-hawser-laid rope; and for denition in this description -it 'will be considered that the twisting togetherof a -multiplicity of lspun yarns makes a strand; fthe twisting of three strands together makes a plain-laid rope; and that the twisting together of three plain-laid ropes makes a cable- :laid or hawser-laid rope. The successive reversals-of direction of twist provide a counterbalancing of the inherent tendencies to untwist, as between the cable, the ropes, the strands, and

the yarns.

Ordinarily, cable-laid ropes are harder and vstiffer, than plain-laid ropes, -but they have the defect that when such a rope in service is ref` quired to bend around a pulley or the like, it disintegrates and. crumblesinteriorly, due to the fact that 'the three plain-laid ropes that compose the cable lare interlocked with eachother wherever 0 they come togetherin the interior of the structure.

Assuming that the cable-is made of three plainlaid ropes each of which Vis a three-strand rope, yit can be observed that each of these plain-laid ropes has a surface which, as one travels along that surface parallel to ythe axis, is a series of alternate crests of strands and contlines or valleys vbetween the strands. 'In the assembling of the lthree plain-laid ropes to make the cable the crests on any one of these ropes successively come tightly into lmesh with the contlines on the other two; andthis is a d istinct'advantage in the process of manufacture `because it is comparable to the meshing together of gear teeth and it assures that the component ropes will go into the cable with exact uniformity of length. And. it is another advantageous feature that this intermeshing, of each rope with each of the others under severe tension, holds them all locked together and tends to distribute any heavy tensile stress among them instantly and equally. I conceive, however, that the premature interior disintegration results from the same. The intertwining Aof the three strands of one rope with two other groups of three strands each, each of which strands lis full of helixes of spun yarns that are full of helixes of fibres, makes 1935, Serial No. 26,708

a multitude and diversity of helixes, such that the cable as whole has greater elasticity 'than would characterize its individual ropes if 4pulled. straight. When a cable is put to the serviceof repeatedly lifting and letting fall a heavy tool, `5 there is, in the aggregate, a considerable distance of stretching and of elastic recovery in the "rope,

as the picking up ofthe Weight tends to lengthen these helixes of elastic bre andas the releasing of the tension lets them return. VAs each rope of 10 the cable stands in a helix around the axis ofthe cable, andthe tensionis applied in the directionof the axisyit is indeed a fact that the tensile impulse received at yone end of the cable is transmitted along the cable by each crest of a strand 1in a component rope pushing against the adjacent strands of the other two ropes in whosecontlines 'it lies, and by these, in turn, pressing others; and if the cable is not altogether straight but runs over a pulley, the action is nevertheless Vsimilar, =20 but with a more obvious localized movement 'of each strand relative to its neighbors in its associated rope. The tightness of the interme'sliingis extreme, but in view of the elastic characterand the helical arrangement of the component bres, I conceive that there is, nevertheless, an ubiquity of movement in the midst `of the cable, fof each strand relative to its neighbors where it is intermeshed with them. Of course'the `movement yis very slight in dimension; but at these `locations rthe yarns and the fibres of each strand do -not lie or move parallel with the yarns and. fibres of the neighboring strands with which they are intermeshed The cross-rubbing makes the friction and abrasion and disintegration which it is an 'object of the invention to eliminate or reduce. I conceive that this evil is caused by the tightness of the intermeshing, coupled with the complexity of the relative movement of tensile elements, which are severely presse-d against eachother in the making of the cable, and. 'whose severity of compression toward the axis is immeasurably in creased when the cable is under heavy stress of duty, because longitudinal tension tends to straighten all of its helixes and to draw theircome ponent substance closer to the axis, and because yof the rubbing libres lying across each other. This makes a complexity of relative movements of tensile elements, engendered by the reciprocating, the slight twistings and untwistings, intermittent stretchings and contractings, the bending and straightenings in passing around a wheel, and the suddenness with which these forces are applied in the particular work 'of well kvdrilling-title whole 'sometimes resulting in a pulverization of the interior of the cable before those fibres which are at the exterior become worn away by the abrasion to which the surface of the cable is subject, and therefore before the cable has contributed that quantum of useful service of which it would be capable, were it not for this failure at the interior.

It is therefore an achievement of the invention to relieve the cable of the devastating fibreagainst-i'ibre abrasive action to which cables hitherto normally have been subject.

It is, nevertheless, an object to preserve all of the general features and advantages of cable-laid rope as heretofore customarily formed and organized, and therefore, to accomplish this reduction of abrasion without destroying the elastic properties of the cable, or curtailing its freedom of innitesimal local movements incidental to normal action, or materially increasing the weight or size of the cable, or decreasing its flexibility.

This is done by introducing a thin exible fibrous partition which, without seriousiy affecting the perfection of intermeshing of crests and contlines, takes the wear between fibres at these locations, endures it better than the rope fibres do, and by its own resistance to abrasion defers the time of direct abrasive contact of rope fibres with each other. And it is preferred to enhance the effect by making this partition of a fibrous material which by reason of adsorptive affinity can act as a carrier of a plastic or liquid lubricant so that severe compression of the partition cannot drive all of the lubricant out of it, because a thin film of the lubricant will insistently cling to the nbre.

It is a further feature that the material preferred for the partition is structurally smooth and resistant to abrasion. So long as it lasts this material is what sustains whatever abrasion occurs; but, as it is not itself a tensile element of the cable, its ultimate loss does not reduce the tensile strength.

These results and the other advantages of cables embodying the invention are attained by laying a thin body of soft but wear-resisting material, as bre cells of practically pure cellulose, of which cotton is an example, between the individual plain-laid ropes which are cabled together to make the cable-laid rope. rThe extreme pressure with which these ropes are closed together in the making of the cable forces the usual perfect intermeshing cf crests and contlines, but actual contacts of strands of one rope with strands of another is prevented by the laying in, at time of the closing of the ropes together, of the said intervening wear-resisting thin body. This may ultimately become worn, by frictional rub of hard bre elements of the ropes thereon, but so long as it remains it serves the double function of first, holding lubricant, and., second, being the sacrifice to the abrasion, so far as any sacrifice occurs, vicariously for the tensile bre.

The c-otton provides a desirably soft bed for the respective rope elements and has great wearresisting quality. Its brous nature tends to promote distribution of wear through the cotton mass, rather than having it immovably concentrated at particular locations.

The partition may be provided in various ways. One is by means of woven coverings preliminarily applied to the individual ropes, or to the individual strands of the individual ropes. In such case the woven coverings come together at the intermeshed core region, when the ropes are closed together, to provide the partition there; and the portions of these fabric coverings which are exposed at the exterior of the rope may be trimmed away after the cable is made, or will become worn away in service by ordinary surface abrasion.

The partitioning body may be rendered more resistant to frictional wear by constituting it a carrier of a suitable lubricant, which may be one for which the cellulose of the cotton, or whatever other material may constitute the partition., has a strong adsorptive anity, so that the extreme compressive forces Within the cable will be ineffective for driving out the lubricant except as a relatively slow process..

It is intended that the patent shall cover, by suitable expression in whatever features of patentable novelty exist in the invention herein disclosed.

In the accompanying drawing:

Figure 1 is an elevation of a piece of cablelaid rope embodying features of the invention,

one of the component ropes being unlaid to show the intermeshing of crests at the interior of the cable, partitioned in accordance with the present invention;

Figure 2 is an elevation of a cross-section of a cable-laid rope having another embodiment of partitioning means at the intermeshed core region;

Figure 3 is a view similar to Figure 2 with still another embodiment of partitioning means; and

Figure 4 is an elevation of a cross-section of a single one of the component ropes, illustrating how that rope may be covered with a material for constituting a partition; and illustrating also how the individual strands of that component rope may be similarly covered.

Referring to the drawing, three ordinary three-strand ropes, 'plain-laid, are represented at i0, l2 and i4, twisted together as usual to form a cable-laid rope.

In Figure l, the component rope lil has its end portion lifted out of the cable assembly to reveal the manner of intermeshing of crests of the several ropes in the interior region of the cable. The pressure with which these ropes are closed together at the making of a cable is so extreme that the deformities of strands which are represented in the several views are, or may be, produced before the cable-laid rope is put into service. 'Ihe invention deals particularly with these intermeshings of strands, the toothand-hollow character of which is represented at i6 and 28 along the helical bed from which the rope Iii has been removed, and at 2S in the removed rope. These deformities result from the mutual compression of the assembled ropes l0, I2 and I4. Each crest of strand of each rope, at this interior region, becomes settled and wedged into a contline between strands of an adjacent rope. Taking a specific instance for illustration, thestrand iof rope i9 was fitted into the contline 2B between the strands 22, 24 of rope l2, with deformation of strand I8 clearly shown at 28, where the two places in which the strands 22, 24 were bedded are apparent. Also, in the strand 24, the place of bedding of strand i8 may be seen at 28.

By considering Figure l as if the element 3u were omitted it will be apparent how, in the prior ordinary cable-laid rope constructions, there is direct contact and pressure in radial direction toward the axis, of strand surfaces which come together in this meshing, so that any relative movement of the inter-engaged elethe appended claims.

fmentsintt-he direction ofthe axis :is-frictional,

Ean'd mutuallyfabrasive, tending ktoward aaapulverstresses and strains of service.

The-.elements -of the Vcable-laid lrope of the "invention are assumed to exercise as here'tofore whatever freedom of 4'movement they have lrelative to each other, when in vuse,\witl:i lthe natural elastic stretching and shrinking, :of the :cable and its sundry helixes of strands ,and vcompo- ,nent `fibres. `But :according to the invention'the disastrous direct frictional .rubbing together of tensile elements incidental to .that .is .eliminated by the introducing of a wear yabsorbing .partition 3B which intervenes between intermeshing parts voi the component ropes. This partition may be of any suitable wear-resisting material; but preferably it should be a `material which does not abrade the fibre ofthe ropes. Preferably it should have such smoothness as -does lnot eny-gend-er abrasion; yand it may be a carrier of lubricant. For this I propose a thin body (of cotton fibre. 'Ilri-lobed bat sheet form is frepresented at 30 in Figure 1; and a collapsed tube of woven V\or .-knitted cotton yarns is portrayed at 32 in Figure 2. In the thin tri-lobed bat form of Figure 1, the permissibility of some relative movement of cotton bres among themselves in the bat, as driven by the relative movements of rope iibres with which the surfaces of the bat are in contact, distributes the frictional drag through the body of cotton iibres, in the sheet, thus fractioning the actual length of this short, possibly-abrasive travel into a number of still shorter lengths, absorbing these in the body of cotton, and imposing this travel, ultimately, in these fractions on the introduced fibre, with very little of the wear, due to the movement of one strand relative to another, being imposed on the actual tensile elements. And a suitable 1ubricant may be carried by the wadding for reducing the abrasion.

Even if the partition 3l) or 32 ultimately becomes Worn away or extruded, before exterior tensile elements of the rope have become unserviceable, its presence will at least have deferred the beginning of interior disintegration, at a cost incommensurately small. After that beginning of direct contact of interior elements, the cable-laid rope Will be fit interiorly for whatever considerable further period of service such a cable has customarily been capable of until its interior elements become unfit. It is an object of the invention however that the slip-partition 30 will be so selected, as to thickness and organization of its material, that it will ordinarily be sufliciently durable to extend the natural serviceable life of interior elements enough to equal that of surface elements, so that the total service to be extracted from each cable-laid rope may be the total that is warranted by the character of its external contacts.

The cotton batting of Figure 1, or the tubing of woven, braided or plaited cotton of Figure 2, are introduced by feeding this bat or tube as a core element which is laid at the axis around which the three component ropes are being closed in the making of the cable. The element thus being introduced at the core can be formed into the three-vaned or tri-lobed shape by a xed guide, just before it becomes pinched between the ropes.

In the structure of Figures 3 and 4 this partitioning effect is attained by means of a fabric cover preliminarily applied to the individual "component ropes, as :in Figurei; `or the .indi- "viclual strands of veach individual :rope .may be -fsimilarly Acovered Vas is suggested in Figure 4.

'The `rportions of the soft fabric envelope which are subjected to exteriorabrasion will become`v` quickly Worn away `when the finished rope is put intofservice, leaving the interior compressed portions in their. initial locations. Or4 the exposed exterior web portions of covering may be slit, by cutting A'them over the helical .contlines where they are not in close contact :with any strand, .and the excess material then may be eliminated.

rIihe practice of this invention is Anot limited to :1t-he specic `materials or'arrangements 'which' are mentioned above as illustrative embodiments, except as :may be expressly 'limited in the zclaims. Thus, in fits broader aspects the invention eis not limited to cellulose for the material of Athe IPMOII; and, if fcellulose, it'neecl .not bethe"y have qualities of smoothness and toughness" x Without the rasping characteristics of manila, sisal and other hard fibres of which cable-laid ropes are made; and it may even be possible that advantage will be found in making the partition of hard fibres, arranged for the slippage to occur in the direction of their length.

So, also, the particular Variety of lubricant is a matter of choice among, for example, petroleum and. graphite or plumbago or other mineral lubricant, and any lubricants of animal or vegetable origin, especially if being of a nature for which the material of the partition has absorptive aflinity.

It will be observed that in the structure described and illustrated the elements are selfretaining. The ropes hold each other, as heretofore; and each wing of the tri-lobular partition is restrained from working out to the periphery of the cable by its being connected across the axis to two similar vanes each of which is firmly pinched,-each will indeed have equally strong reason to move toward its own section of :the periphery,-so that the tri-lobed structure tends to hold itself in position. Each sheet-lobe is deeply contorted through its tooth-and-hollow intermeshings, under high pressure, so that it is firmly gripped. In the forms of Figures 2, 3 and 4 the fabric sheet stands in two ply thickness. The greater restriction to which individual fibres become subject when organized in yarns and woven fabric is thus balanced by the freedom of movement which may exist between the two ply, as well as at the surface where each bears against the iibres of rope.

I claim as my invention:

1. A cable-laid rope made of hard vegetable libre, comprising a plurality of plain-laid ropes twisted together, with the crests of each meshing between crests of others, combined with a thin body of brous collapsed-tubular sheet material intervening between intermeshed portions of the ropes thereby relieving intermeshed tensile elements of frictional wear upon each other.

2. A cable-laid rope, comprising a twisted group of intermeshing ropes, constituting tensile elejoin it in the twisted group; combined with a body of non-tensile partitioning material, intervening between rope crests which thus intermesh, for receiving abrasive wear at the intermeshed surfaces when the cable is working, and incapable, due to its non-tensile character, of functioning as a tensile-stress-bearing part of the rope.

3. A cable-laid rope as in claim 2, in which the group consists of three-plain-laid ropes, and in which the partitioning material is of cellulosic composition.

4. A cable-laid rope as in claim 2, in which the partitioning material is of brous composition.

5. A cable-laid rope as in claim 2, in which the partitioning material is of unspun cotton fibres laid in sheet form.

6. A cable-laid rope as in claim 2, in which the partitioning material is integrated in self-sustaining sheet form.

7. A cable-laid rope as in claim 2, in which the partitioning material is a plurality of sheets overlying each other.

8. A cable-laid rope as in claim 2, in which the partitioning material is fabricated of cellulosic yarns.

9. A cable-laid rope as in claim 2, in which the partitioning material is combined With a lubricant for which the partitioning material has adsorptive arnity.

10. A cable-laid rope as in claim 2, in which the partitioning material comprises entrapped portions of sheets of fabric, which sheets, each as a whole, severally enwrap one of the intermeshed tensile elements of the cable.

11. A cable-laid rope as in claim 2, in which the said group consists of three plain-laid ropes, and these three ropes have their crests on their axial sides so deformed that these crests stand in contact with each other in the axial region, except as the said partition intervenes; and in which the said partition is a three-leaved sheet element, extending axially in a curve surfacing the said crests of the axial region, sinuously crossing and recrossing the axis in following the said deformed surfaces of their intermeshing, and extending outward from the axis in sinuous curves following the radial intermeshing of the crests.

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