US2022683A - Rope - Google Patents

Description

ea 3, 593% Q, MacKlNNON ET AL ROPE Filed Oct. 10, 1952 Ellis 6U. 51's waiter Patented Dec. 3, 1935 UNITED STATES ROPE Charles MacKinnon and outh, Mass, Company,

Ellis W. Brewster, Plymassignors to Plymouth Cordage North Plymouth, Mass., a corporation of Massachusetts Application October 10, 1932, Serial No. 637,008

8 Claims.

This invention relates to improvements in rope. More particularly it relates to rope twisted of vegetable fibre, whether single strand, or formed of a plurality of strands. Thus the invention may be considered as applicable to rope in general except wire rope. And while its greatest utility may probably be found in ropes made of long and hard fibres, such as manila and sisal, utility will be found also in rope made of the thorter and softer fibres.

It is a result of the invention that the making of rope with a softer lay of the strands becomes practicable, without danger of the arising of internal back kinks. In ropes of ordinary con struction such kinks may occur when the rope is back-twisted, or is so handled that some of the yarns become tighter than normal and work into the midst of others, as by inner yarns being bulged into the outer. In such cases .a restoration of the normal rope structure is diflicult, or even impossible. The consequencies are sometimes serious. It is not merely that the work in which the rope is engaged must be suspended, for correction or replacement of rope; but the kinking is destructive of the rope; and the failure may occur at a moment when failure or unavailability of the rope is disastrous to surroundings. The danger is present in all rope of ordinary construction, according to prevalent standards, particularly in those types of rope which are made soft for easy handling. Among large ropes back kinking is perhaps the most frequent cause of premature destruction of the rope. I It may result, for example, from wrong judgment, ignorance or carelessness in the repeated coiling of a rope; and it may occur in a free rope as well as in a rope which is in capstan, or other severe use.

As compared with ropes hitherto known, the rope provided by the invention is considerably more stable and resistant to distortion. In consequence it can safely be made with a relatively loose and long lay. With the long lay and stability come considerable improvements in strength, in general utility and in durability. There may also be increase of flexibility, as compared with rope made from the very same stock accordance to standards which heretofore have been generally accepted as good. Strength results because a pull on rope which has a longer lay produces less .of a shearing stress on the fibres, since their angle to the direction of pull is less. This angular improvement contributes also to durability, because the friction of fibre across fibre becomes less, during that slipping which occurs as the rope when in use becomes repeatedly bent and straightened, or stretched tight and relaxed.

It is therefore one object of the invention to provide a strand structure wherein the constituent yarns are maintained against disarrangement, and especially the disarrangement known as back-kinking, in handling, use or abuse of the rope. The element, by whose introduction into the strand this is accomplished; has no 5 function of contributing directly to the tensile strength of the rope. Its structure and function are those of a septum, a means for positively holding the yarns of adjoining groups against mutual disarrangement. Specifically, it hinders, the yarns of one course, when tightened by a back twisting of the rope as a whole, from intruding themselves between yarns of an adjoining course, by force of that same back twisting.

A further feature of the invention resides in the fact that said introduced means may carry a suitable substance absorbed or adsorbed within it, liquid, plastic, or colloidal, which may serve any ofseveral functions, for contributing to the flexibility of the rope, and for prolonging its .useful life. Thus, it may hold material which constitutes a lasting source of lubricant, for gradual distribution among the yarns; or which provides lubricated slip surfaces between inner and outer coursesof yarns, over which surfaces 25 said yarns readily may slip during flexing of the rope; or it may be a substancewhich prevents or delays the entrance of water, or of other deleterious liquid or fumes.

Still another feature, which is an incident of the soft lay of the elements together, is that the improved rope maybe easily spliced.

Thus, in general, the invention provides for the making of rope which has greater strength per pound of its 'own weight than a rope of similar dimension and stock, made according to hitherto customary specifications; has greater stability; and may be so designed-as to have increased and easy flexibility; all Without danger of back kinking. These improvements tend to increase its 40 utility; to prolong its useful life; to facilitate its handling; and, in the operation of the rope, to reduce the power required and to increase the elficiency of the rope as an instrument transmitting power.

The invention attains these results by introducing a septum between groups of yarns or fibres which are adjoining each other in a rope strand. In most cases these will be groups which adjoin in interior and exterior relation. The septum may beformed of strips of a suitable material, wrapped helically or otherwise around the one group and separating that from the adjoining group. The material may be various, as paper, cloth, rubber, etc., strips, which are materials in sheet form, simple or composite, or even may be a winding of suitably strong twine, thread or fibre. The wrapping of the strips may be executed with successive convolutions overlapping, making a closed sheath; or the convolutions may have open spaces between them, as desired; and the pitch thereof may be greater or less than the pitch of the yarns. Also the strips may be wrapped in the direction of twist of the strand, or counter thereto, or may be merely folded about the groups which they enclose. Or in some cases the septum may be a strip which is fed in with the yarns, into the strand forming tube, and is thereby folded, laterally and without individual twist, around the body of fibres or yarns with which it is to be associated.

The septum when arranged between exterior and interior groups, for example, maintains a barrier which prevents the yarns of the interior when the rope is back twisted; and on other occasions it would constitute a barrier support at the surface of the interior group, effective to prevent tightened exterior yarns from sinking between loosened interior yarns if the exterior should ever become constricted thereon at a time when those inner yarns were loose.

As a result the yarns, both exterior and interior in a strand, may be assembled together with a much softer and straighter lay than has been usefully practicable heretofore; and the greater strength and other said benefits are attained with safeguard against back-kinking.

It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentablenovelty exist in the invention disclosed.

In the accompanying drawing, which is a schematic representation of different embodiments of the invention,

Figure 1 shows a piece of three strand rope embodying features of the invention, with end portions of two strands unlaid;

Figures 2, 3 and 4 are cross sections through strands of other ropes in which;-in Figure 2, the septum is arranged around a group of center yarns to separate them from their cover yarns, but is laid straight along the axis and is wrapped by being folded around the center group; in Figure 3 the septum is between adjoining groups of interior yarns, as well as around them; and in Figure 4 the interior tensile elements are unspun fibres whose groups are separated by septa that lie between these groups but do not surround them; and v Figure 5 shows material that may be used for the septum, being two plies of paper with unspun fibre between them.

Referring to the drawing, it will be understood that the pitch at which the strands ID of a rope are laid for the core yarns I! of each strand, or the intermediate yarns I4 or the exterior yarns l6 thereof, is a matterwhich is determined by the rope maker, and that it may vary over a wide range, according to the desired duty of the rope and the judgment of the maker. The drawing therefore, in these respects, is merely conventional to represent a rope structure.

When the invention is to be embodied in a rope, the rope may safely 'be designed with its angle of lay more nearly parallel to the axis, due regard being had to the expected duty of the rope,

than would be good practice if the rope were to ity of the core is desired, that the lay may be made particularly long.

Each strand [0 comprises whatever kind of stock is customary or desired, herein assumed to be manilla or other long and strong vegetable 5 fibre stock; and each may embody a multiplicity, of spun fibre yarns I2, 14, I6, which themselves are grouped and twisted together into the strand form, according to. any choice among the many desirable relations. 10

The invention, however, in the form illustrated in Figure 1, makes a distinction between interior and exterior layers of the yarns; and introduces septa l3, l5, which segregate the yarns of each group.

The septum may be in the form of strips of tough flexible sheet material, as paper, cloth, rubber or other, but it is believed that some variety of tough flexible organic material will ordinarily be found best, wound around the interior group 20 of yarns. The winding may be either with an overlapping of successive convolutions of the strips (as at the extreme left of Figure 1) or without such (as at the extreme right) or even there may be open spaces -(not illustrated) between the 25 convolutions. The strips l3, l5 may be laid with pitch equal to or greater than the pitch with which the yarns are laid in their strand, or with a shorter pitch as illustrated, in which latter case a greater binding effect is attained. Also 30 the shorter pitch of the strips approximates more nearly a 90 crossing between strips and yarns, and produces a firm support for the exterior yarns l4 or IE which are laid directly upon the wrapping.

The strips l3, 15 may be wrapped with direction of lay opposite to the direction of lay of their enwrapped yarns, if desired. Also, the exterior group of yarns may be laid in direction opposite to the direction of lay of the interior 40 yarns, if that be preferred.

The segregation of yarns in groups within a strand, and the provision of a septum or wrapping for the interior group I2 or H, which septum underlies the exterior group It or IS in a finished 45 strand, is particularly important in that it permits of the yarns of each group being assembled with a soft lay. The rope stabilizer, which is the septum or wrapping I3, I5, provides means for preventing subsequent intrusion of yarns of one group 50 into the other.

The stabilizer is a barrier which exercises its most important function whenever the rope experiences distortional stresses which tend' to thrust yarns of one group into the midst of yarns 55 of the other group.

It will be understood that in an ordinary threestrand rope, for example, each strand is composed of spun yarns; or sometimes may contain a body of fibres which are laid in without be- 60 ing spun, or being only slightly twisted. Initially, this group of yarns and/or fibres was twisted in a one direction, right or left, to make a strand; and

then three of these strands were laid together and twisted in the opposite direction to make the rope. 65

After it is in use, such a rope may happen to experience aback twisting force, in the course of being handled in eitherof several. ordinary ways; and when this occurs to the rope as a whole, the

. untwisting of the rope produces a bulging of the 70 strands, and in each strand makes a complex distortion and displacement of the mutual relation of the component yarns.

By the invention the yarns are held in their original group formation, and are held against yarns, affords a barrier to the extrusive force by which interior yarns would tend to thrust apart their adjacent exterior yarns. It prevents deep or permanent penetration of the outer yarns by kink ornubs of the inner.

The introduction of the septum makes the particular rope somewhat stiffer than it would have been without the septum; but the presence of the septum makes it possible to design a rope so that even when thus somewhat stiffened it is more flexible than would be practicable fora rope of the same order without the septum.

The material of this septum l3, I5, if suitably laden with oil or grease, may serve also as a lubricating agent, and can hold the grease for gradual distribution through the strand. Whether or not it thus distributes lubrication, the slip surface, which the septum presents between interior andexterior groups of yarns, helps the respective groups of yarns to execute that slipping which occurs when a rope bends around a pulley, and when a rope is subjected to tensile stress, because it makes less friction and less fibrebreaking stress.

For the holding of a lubricating compound as a source of distribution to yarns during life of the rope, a sheet-material having absorbing power may be employed, as felt; for affording an easy slip surface, a tough paper with calendered surface. If the core yarns have extra lubricant, and this paper wrapping be laid with its own convolutions not mutually overlapping, then the interior yarns can serve as somewhat of a reservoir for lubricant that will eventually work its way to the exterior yarns. Cellophane may be regarded as a variety of paper, and this special characteristic is noted, that whereas ordinary paper has a surface of distinguishablefibres, cellophane or like material has a smooth continuous surface, and the abrasive effect of yarns slipping over its surface will be less, and the life of the septum will not so soon be affected by abrasion.

Figure represents a composite septum, having two strips l5, l5 of flexible sheet material,

which may be of any of thematerials mentioned. in connection with the septa l3, l5. These stripsare stuck together by a suitable water-proof adhesive substance, such as asphalt, embedded in which is a series of longitudinally disposed filaments l5 which, preferably, are unspun fibres of vegetable origin, as hemp orsisal, for example, extending side by side in approximate parallelism.

-The fibres may be introduced by laying them on one of the strips I5 I5 during the operation of putting the strips together, which preliminarily will have been coated on one face with the adhesive; and by pressure these fibres become firmly secured in the two-ply structure. Such a septum, having superior qualities of strength, durability and tenacity, may be employed in place of the single-ply and un-reenforced. septa previously described.

It is preferable that the septum surface presented to theyarns be a continuous sheath, but owing to difference of pitch a septum made of discontinuous small barriers may provide the desired protection, especially if wrapped at a pitch .diverse from those of the tensile yarn-groups ing of the rope, because the resulting fragmentary, discontinuous, sheets would still remain in place, being inescapably enclosed. Moreover, the paper may be on one side adhesive. For waterproofing a rubber treatment may be employed, vulcanized or not as may be suitable.

Constructions embodying the invention are not limited to single ply of paper, and, if there be more than one ply any useful material'may be incorporated between them. More than one ply may be desirable when the rope is large or the number of center yarns very large, or the core made of a single large body of unspun fibres, which last, so far as the claims herein are concerned, is to be regarded as the equivalent of a body of spun yarns.

Figure 4 illustrates a strand having a core of a larger body of unspun fibres; and Figure 3 a core of a large body of yarns. Through the midst of this body, in each instance, are septa which prevent disarrangement of fibres or yarns from one part of the core into another. These are shown in order to indicate that the septa are not necessarily laid helically, and that they may sub-divide v a body. In Figure 3 the body of yarns is inquadrants l4", and a septum l5" covers three sides of each quadrant, two radial and one peripheral. Each strip l5 may be applied to its own group of yarnsbefore the groups are assembled, either being wrapped helically, or being laid parallel to the axis and formed about its quadrant by a special die or by the general die which forms this part of the rope. If having adhesive surface, these septa may adhere to each other after being assembled. In Figure 4 the septa l5' are for each of two opposite, quadrants, and each is V-shaped,- thus holding the bodies of unspun fibres M' in order among themselves but not circumscribing them.

In Figure 2 a large core of spun yarns M, 40 within outer yarns I6, is shown surrounded by a septum l5 which is laid parallel to the axis and is formed around the core M by mere bending;

and to indicate this in the drawing the edges are represented as being not quite closed together. ,45

However, considering the extent of bending which most ropes must undergo, the helical lay of septum indicated in Figure 1 will probably be found better for most purposes. And for a similar reason the use of finely wrinkled stock, as crepe, will facilitate a bending of the rope with less fracture of the septum.

If a metal strip be employed for the septum it should be laid s0 loosely that it will not interfere with the proper functioning of the tensile elements of the rope, which, being of fibre, are subject to considerable variation of dimension between stress and, slack conditions, and dry and humid conditions. Such a metal strip may be used if it be sufficiently flexible and sufliciently loose in dimension to accommodate itself to these conditions.

It will be understood that in the cordage industry strands such as are here represented as being compounded with other strands, to make a plural strand rope, are well known to be each capable of use as a rope by itself; so that the terms strand and frope are more or less interchangeable.

' The claims:

1. In a kinkable rope strand, a multiplicity of tensile yarns of hard vegetable. fibre arranged in an interior group, and 'a multiplicity of tensile yarns of hard vegetable fibre arranged in an exterior group, surrounding the interior group, the yarns of one of said groups being laid together with such a softness and looseness of lay that, upon back-twisting of the strand, fibres of the other group might become enmeshed therein, and cause kinking of the strand; combined with an anti-kink device comprising a thin, flexible sheet of non-metallic material having a smooth surface, interposed in the strand, separating by a minute distance the group of interior -yarns from the group of exterior yarns; said flexible sheet being a bridge over spaces between successive adjacent yarns of each group and being means operative to prevent kinking of the rope when it is back-twisted.

2. A kinkable rope strand made of hard vegetable fibre tensile elements, comprising an interior grouped fibre structure, and an exterior grouped fibre structure closely surrounding the interior group; combined with a flexible parting device intervening as a septum between the said interior and exterior groups; one said grouped fibre structure having a long pitch of lay of its elements together, and a softness of lay of them together, such that it is susceptible of being easily penetrated by elements of the other group; and

said parting septum constituting a thin partitionin the nature of a sheet, and of vegetable fibre origin, adapted to bridge any spaces that may occur between elements at the adjacent surface of either group, preventing protrusion of elements of one group among elements of the other group; and said septum being of flexibility at least as great as the order of flexibility of a said, group of fibre tensile'elements, and having tensile strength of an order less than the order of tensile strength possessed by the main tensile elements them together, such that the group is susceptible of being easily penetrated by yarns of the exterior group which are to enclose the interior. yarns, folllowed by the applying around the interior group of yarns of a flexible barrier device for bridging spaces that may occur between yarns of the interior group; and then laying exterior yarns around the barrier, which latter prevents protrusion of yarns of one group among the yarns of the other group.

4. A kinkable rope comprising one or more strands wherein'the tensile elements are wholly of vegetable fibres, each strandcomprising a plurality of groups of tensile elements of which one group has its elements laid togetherwith softness and looseness oflay such that, upon backtwisting of the rope, elements of one group might become enmeshed with elements of another group; combined with a group-parting septum whereby intrusion of elements from one group into an adjoining group is resisted, said groupparting septum comprising flexible fibrous material laid in a thin formation which, in each of the thereby-parted adjoining groups, bridges units in that group which adjoin each other at the surface of that group; the said thinness of formation being such that the septum separates the groups by a distance less than the radial thickness of the tensile elements, and the said flexibility being at least as great as the order of vegetable fibres, each strand comprising a plurality of groups of tensile elements of which one group has its elements assembled together with such softness and looseness of lay that, upon back-twisting of the rope, elements of one group might become enmeshed with elements of another group; combined with a group-parting septum whereby intrusion of elements from one group into an adjoining group is resisted, said group-parting septum comprising a sheet of paper or the like laid between adjoining groups of elements, and having flexibility at least as great as the order of flexibility of a said group of fibre tensile elements.

6.-A kinkable rope comprising one'or more strands wherein the tensile elements are wholly of vegetable fibres, each strand comprising a. plurality of groups of tensile elements of which one group has its elements assembled together with" such softness and looseness of lay that, upon back-twisting of the rope, elements of one group might become enmeshed with elements of another group; combined with a group-parting septum whereby intrusion of elements from one group into an adjoining group is resisted, said group-parting septum comprising flexible fibrous material laid in a formation which is devoid of twisted yarns and whose flexibility is at least equal to the flexibility of a said group of fibre tensile elements.

'7. A rope comprising one or more strands wherein the tensile elements are wholly of vegetable fibres, each strand comprising a plurality of groups of tensile elements, combined with a group-parting septum whereby intrusion of elements from one group into an adjoining group is resisted, said group-parting septum comprising flexible fibrous material laid in a helical course in the rope, along the surface between adjoining groups, said seputm having a surface sufficiently.

smooth for the said groups to slip freely over it,

and being devoid of twisted yarns, and being suiflciently stiff and strong to bridge spaces that may open in either of the groups and so to prevent entanglement of part of the other group therein.

8. In a kinkable strand of fibre rope, having a group of fibre elements assembled together as a tensile core of the strand, formed with flexibility, and with looseness of lay together such that, by a back-twisting of the strand, the fibres in one por- 55 tion thereof-might, if unrestrained, become enmeshed with fibres in another portion thereof, and having a group of fibre tensile elements laid around said core elements; combined with an anti-kinking septum within the core, dividing said 00 core into portions, and maintaining adjoining portions in normal positions relative to each other during subsequent manipulation of the rope; said septum being a thin, flexible element of vege-

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