US2779149A - Non-rotating wire ropes - Google Patents

Description

Jan. 29, 1957 H. SCHULLER 2,779,149

NON-ROTATING WIRE ROPES Filed Oct. '7, 1952 INVENTOR. 627/ J'cH ULLEA ill Q94 NON-ROTATING WIRE ROPES Heri Schuller, Limbach, near Hamburg, Saar Territory, Germany, assignor, by mesne assignments, to George H. Rother, South Plainfield, N. J. 1

Application October 7, 1952, Serial No. 313,553

Claims. (Cl. 57148) (1) l+6+l1 or 1+6-}- 1?. strands (2) 1+3+9+15 strands (3)-l+6+1l+17 or l+6+l2+18 strands wherein 1 represents the central core and the successive numbers represent the number of the wires or strands laid in successive layers in the order named in respect to said core. The latter may itself consist of a strand or solid wire of any suitable material. Thus, according to Formula 1, six inner strands are arranged be- 2,779,149 Fatentecl Jan. 29, 1957 Thecore of the rope may consist of a strand or of a solid wire, depending on the type or diameter of the rope, as will be further understood from the follow- (III) ing.

The bracketed numbers in the foregoing formulae indicate that the strands may be replaced by a corresponding number of single wires for ropes of relatively small diameter.

The invention will be further understood by the fol-, lowing detailed description, taken in conjunction with the accompanying drawing, forming part of this specification and wherein:

Figures 1, 2 and 3 are diagrammatic cross-sections through preferred wire rope constructions according to tween a core and eleven outer strands, while according to Formula 2, two inner layers of three and nine strands, respectively, are arranged between the core and a layer of fifteen outer strands.

In such a construction, all the strands have substantially the same diameter and wire structure. The core may consist of a rope of hemp or other suitable material. Each strand is laid separately, in such a manner that the inner layer or layers between the core and the outer or top layer, forming so to speak an inner rope, are laid in a direction opposite to the outer layer, in order to secure the desired freedom from twist or rotation of the rope, such as when used to lift an unguided load.

A disadvantage of the known constructions is due to the crossing or intersection of the wires of the individual layers, on the one hand, and to the presence of relatively large open spaces between the layers, on the other hand, resulting in a limited engagement or contact surface between the layers. Thus, the constructions can at best be designated as reducing rather than eliminating the tendency of the rope to rotate and to unwind under load.

Among the objects of the present invention are to provide an improved and novel construction of the inner layers or inner rope of a multi-layer wire rope, while using approximately the same number of outer layers as in conventional rope designs; to more fully utilize a given cross-section or to improve the packing factor of the rope; to increase the breaking strength of the rope; to strengthen the structure of the inner strands; to increase the number of inner strands in the interest of improving the freedom from rotation under load; to enable the use of strands or wires of adjacent layers hav ing an equal diameter; to enable the use of strands for the entire rope made of substantially the same type of wire of equal diameter; to substantially eliminate crossing or intersection of the wires of the inner strands or layers; and to provide an improved core structure suitable for ropes according to the invention as well as designs known in the prior art.

-'The above objects of the invention are obtained esthe above formulae 1, II and 111, respectively;

Fig. 3A is a perspective view of a piece of rope with one end cut to show the core, the inner strands and the outer layer arranged in accordance with the invention; and

Figure 4 illustrates a preferred core construction for multi-layer wire ropes according to the invention.

In all the figures of the drawing, the strands are represented by circles for simplicity of illustration, the wires being indicated for only some of the strands (Figure 2). In this representation, the circles denoting the wires or strands in a layer do not touch, since the sections are. actually ellipses rather than circles, as shown in the drawing. r

i In all the figures, the core is designated by the letter a, and the consecutive strands or layers, starting from the inside, are designated as b, c, d and e, respectively. The drawing clearly shows the interengagement of the inner strands or layers which are laid in parallel or withequal pitch or length of the lay, while the outerstrand (d according to Figures 1 and 3, 2 according to Figure 2) is wound on top of or in cross lay arrangement with respect to the inner strands. As pointed out, the innermost strand b next to the core a may consist of a layer of solid wires, such as shown in, Figure 2.

' diameter. The laying of the inner strands b and 0 will 7 wires (b) plus a 7-wire central strand or core (a).

be further explained hereafter." 7 7 Referring to Figure 2, this shows a construction of (9)+9+9+15=' 3 strands (c, d and e) plus 9 solid other words, 18 inner strands (c and d) are combined with 15 outer strands (e). The 24 strands of the layers d and e are of equal diameter and wire construction (7 wires each, in the example shown). The strands of the layer 0 are necessarily of a lesser diameter, i. e. about one-half of the diameter of the strands d and e, and comprise each, in the example shown, 3 wires. For relatively small diameter ropes, such as from 6 to 11 mm., the strands d and e may consist each of 3 wires of equal diameter, while the layers a, b and may be constructed of a corresponding number of solid wires according to the designation (1) +(9) +(9) An alternative of the foregoing construction is the following: l+(8)+8+8-1-14 =30 strands plus 8 individual wires plus 1 core strand, for which the same considerations apply as are given hereinabove.

Referring to Figure 3, there is shown a construction of 7+ 7+ 7+ 18= 39 Strands In other words, 7 strands of the layer b are combined with 14 strands of the layer c1c2, resulting in 21 inner strands (b, 01, c2) and 18 outer strands (d). The 7 strands of the layer 5 are of the same diameter and construction as the 7 strands c1, while the 7 strands 02 are of a lesser diameter, about two-thirds of the diameter of the strands 01 in the example shown. The core a in the example shown may consist of 19 wires. The core may also consist of 1+7 thin strands or solid wires.

If, with the core strand consisting of 18 to 19 Wires, the construction of the individual strands is suitably chosen, such as with the strands b, 01 and d each comprising 7 wires and the strands 02 each comprising 3 wires, it is found that, in such a case, all the wires of the rope, with the exception of some of the wires of the core a, will be of about the same diameter, thus making it possible to use wire of approximately the same gauge throughout and to thereby considerably simplify the manufacturing operations and to reduce the cost of the rope.

With reference to the laying of the inner parallel strands b and '0, Figures 1 and 3, and c and d, Figure 2, i. e. the strands forming the inner rope between the core a and the outer or top layer d or e, respectively, it will be understood that with the wires of these strands all being laid or arranged in the same sense or rotation, the wires of adjoining strands will cross each other at their points of contact or intersection. In order to avoid these undesirable crossings, the sense of the lay or rotation of the wires of one inner strand such as c, Figure 2, is chosen to be opposite to the sense of the lay of the wires of the adjacent inner strand, i. e. strand :1 in the example refeifred to.

Fig. 3A is a perspective view of a piece of rope with one end cut open to show the inner core a, the outer covering layer it and the two intermediate layers consisting 'of strands b and c. As shown the latter are layed with the same direction of rotation and having an equal pitch, whereby the strands c fit in the grooves between the stfarid b. Moreover, the wires 0' of the strands 0 have a twist which is opposite to the twist of the Wires b of the" strands b, whereby the wires c' fit in the grooves between the wires b. This results in improvedcompactness as well as non-rotatability ofthe rope together with the outer layer of strands d which are arranged in an opposite ray to the strands b and c.

This new rope construction or design according to the invention has the following advantages: (a) an increase of the total breaking load of the rope by about (b) the elimination of one of the operating steps in the laying of the inner rope in the case of a three or multilayer rope structure (Figures 2 and 3); (c) the absence of any wire crossings within the inner rope and-consequentstrengthening of the entire rope structure; and (d) incre sed freedom from or resistance against rotation or twisting of the rope under load.

In non-rotating ropes constructed according to the prior art, the inner layers are subjected to a greater stress, since for practical reasons it is not possible to increase the length of the lay of the outer strand beyond a certainliniit advantages of the construction of the inven tion in this respect will be evident.

In the designs I and II, the layers at and e comprise 6 more strands than the adjacent inner layers c and d, respectively. As a result, the diameters of the strands of both layers may be substantially equal, although the invention is by no means limited to this construction. Evidently, the outer layers may have a different number of strands, such as shown by the design Ill, Figure 3, without deviating from the scope of the invention which is concerned essentially with the construction or arrangement of the layers inside the outer layer comprising the so called inner rope.

The core of known multi-strand wire ropes may itself consist of a strand or a center rope made up of a plurality of wires and/or strands. Such a rope then serves as a core about which are laid the main strands or layers of the rope. According to a further feature of the invention, there is provided an improved core or center rope construction suitable for multi-layer spiral ropes according to the invention as well as other types known in the art. M A disadvantage of all known core constructions is the fact that the main strands of the rope are in substantially point-to-point contact only with the core, whereby, with the rope passing around a number of pulleys and being subjected to considerable tension, excessive pressures will occur at these points, resulting in a substantial reduction of the life of the outer strands and in turn of the entire rope.

A wrapping of the strands with hemp, or the packing of hemp strings in the outer grooves between the strands, has the disadvantage that the metallic cross-section of the coreis substantially reduced, while the hemp will become deteriorated and worn in time, thus leaving unde-' sirable open spaces and resulting in a loosening of the entire rope structure.

The corefor a two-layer parallel-laid spiral rope, hav ing about eight or nine strands in each layer, may also consist of a central strand about which are laid a number of individual wires, the latter serving to relieve the inter sections between the main strands and the strands of the core. Such an arrangement, however, is limited to ropes of relatively small diameter, since for the larger diameters the individual wires will become too heavy.

According to the present invention, there is provided an improved core construction, especially for multi-strand ropes, which substantially avoids the above defects; which makes it possible to substantially reduce the manufacturing time and labor; and which will result in increased metal cross-section of the core as well as in protection of the wires contacting one another within the rope.

These objects are obtained by a core construction corn-'- prising essentially a layer of strands and a layer of an equal number ofindividual wires, both said strands and wires being laid around a central wire in a parallel lay or winding arrangement. The outer wires of the strands are chosen as thin as possible. As a result, they may be of a material having a relatively low strength, such as irori, and are preferably coated with a layer of zinc; or equivalent material. In order to further simplify the fabrication, the strands and individual wires of the core may be laid jointly with the main strands of the rope in a single operating step by a parallel lay or winding oper= atio'n, i. c. with the pitch of the spirals of all the strands and individual wires being substantially the same.

Referring to Figure 4, there is shown diagrammatically a core *strn'ctiire of this type according to the invention. Six individual or solid wires m are laid ar'oi'lnd central wire I, about which there are laid in turn and in the same sense six 1+9 wire strands n, in such a manner that the latter engage the grooves between adjacent wires m and do not intersect or cross the latter, as clearly understood from the drawing.

This center rope may serve as a core for the main rope comprised, in the example shown, of- :1 number er strands shown in dashed lines in the drawing. Alternativel'y, a multi-layer main rope maybe provided, in place of the single layer, as will be readily understood. Such a core construction has the, advantage over the known designs of a substantially reduced manufacturing time as well as the absence of any .wire intersections or cross-over points within the core.

, Furthermore, by constructing, for instance, the strands rt'to consist of 1+9 wires h and g, respectively, whereby the latter'advantageously consists of wire of iron coated with a layer of zinc, there is provided a kind of cushioning effect for the main strands. This, in turn, will avoid damage to the main strands of the core when the rope is subjected to a considerable tension under load. This cushioning effect is improved by the lubricating action of the zinc layer which also provides a certain protection against corrosion of the core and the outer wires of the rope proper.

The invention may go a step further by jointly laying the six strands and the six individual wires of the core together with the six strands of the rope in a single operating step. This is again carried out by a parallel lay method, in such a manner that each of the main strands 0 engages two of the neighboring strands n, as clearly shown by the drawing.

The advantages of this construction compared with previously known designs are the following: (a) an increase of the metal cross-section of the core due to the fact that the strands of the core are located in the grooves between the main strands and, accordingly, may have a greater diameter; (b) a better mutual support of the main strands and the strands of the core and, in turn, a more favorable pressure distribution throughout the rope, thus enabling a full utilization of the effect of the zinc layer; (0) an increase of the compactness and strengthening of the entire rope structure; and (d) elimination of a separate operating step in producing the core.

By alternating the sense of rotation of the wires, such as from a cross lay for the main strands (0) to a parallel lay for the strands of the core (n), or vice versa, intersections or cross-over points between the two strands may be completely eliminated by a proper choice of the spiral pitch of the wires.

The foregoing will be further understood by reference to the following practical example:

Assuming a six-strand wire rope having a diameter of 19 mm. and made according to known methods to contain a core consisting of six strands of seven wires of 0.75 mm. each and a central strand of seven wires of 0.8 mm. diameter, this Will result in a total metal cross-section (of 22 mmfi Assuming further a strength of the wires of 160 kg. per mm. the total breaking strength of the wire will be 3,520 kg.

Referring now to the improved construction according to the invention, the core may comprise 6 strands (n) each consisting of 11 wires of 0.55 mm. diameter and a central wire of 1.5 mm. diameter plus 6 individual wires =(m) of 1.05 mm. diameter plus one central wire (I) of 1.2 mm. diameter, resulting in a total metal cross-section of 32.6 mmf or a 48% increase compared with the previous construction. Assuming again a strength of 160 kg. per mm. for the single wires, totaling 16.9 mm. :and 80 kg. per mm. (iron) for the outer wires of the strands of the core, totaling 15.7 mmF, the breaking load of the core will be 3,950 kg., that is, an increase of 430 kg. over the previous construction despite the use of iron wires. By the use of thin iron wires as a cushioning :means, it is furthermore possible to employ center and findividual wires of a higher strength, such as for instance of 190 kg. per mmfi. In this case, the breaking load of :the rope will be further increased to 4,450 kg.

Regarding the manufacturing times, tests have shown 'that a thousand meter core according to the old construc- :tion would require about fourteen hours, while the time :for laying the new core of an equal length is reduced to inner central wire.

about eight hours. Afurther advantage of the new core:

of the cross-section, while the increased diameter of the center and individual wires of the core, laid with a 'rela-, tively small pitch within the main orouter rope, afford a substantialrelief for the main strandsof the rope under load. Furthermore, the use of iron wire for the outer wires of the strands of the core results in a relatively low internal or permanent stress obtained as a result "of the spiral lay of the strands of the rope.

If the diameter of the rope is reduced to such an extent that the strands (n) of the core comprise only three wires, the strength of the latter is chosen to comply with the special requirements and purposes to which the rope is to be put. With still further decreasing rope diameter, the core is preferably manufactured with the six strands n replaced by individual wires, whereby the core will now consist of two layers of individual wires laid around an This construction is especially advantageous for thin wire ropes, such as used on aircraft for remote control or similar applications. In the latter case, all the wires of the core preferably consist of bare steel of high tensile strength.

In the foregoing, the inventionhas been described with reference to a few illustrative devices. As will be evident, numerous variations and modifications, as well as the substitution of equivalent elements and materials for those shown and described, may be made without departing from the broader scope and spirit of the invention, as defined by the appended claims. The specification and drawing are accordingly to be regarded in an illustrative rather than in a limiting sense.

I claim:

1. A multi-layer spiral rope comprising a core, a plurality of intermediate layers each comprising a number of strands, the strands of all intermediate layers being laid with the same direction of rotation and having an equal pitch and the direction of the twist of the wires of the strands of one intermediate layer being opposite to the direction of the twist of the wires of the strands of an adjacent intermediate layer, and a covering layer comprising a number of strands upon said intermediate layers and having a relative sense of rotation opposite to said intermediate layers.

2. A wire rope as claimed in claim 1 comprising a first layer of six intermediate strands, a second layer of six intermediate strands having a diameter about twice the diameter of said first intermediate strands, and an outer layer comprising twelve elements each having a diameter equal to that of said second intermediate strands and enclosing said intermediate strands and core.

3. A wire rope as claimed in claim 1 comprising a first layer of nine intermediate strands, a second layer of nine intermediate strands having a diameter about twice the diameter of said first intermediate strands, and an outer layer comprising fifteen strands each having a diameter equal to that of said second intermediate strands and enclosing said intermediate strands and core.

4. A wire rope as claimed in claim 1, comprising a first intermediate layer of a given number of strands, a second intermediate layer comprising twice the number of said first intermediate strands, one half of said second intermediate strands being of equal diameter to said first layer of intermediate strands and the second half of said second intermediate strands alternating with the strands of said first half and having a diameter about two thirds of the diameter of said first intermediate strands, and an outer layer of strands enclosing said intermediate strands and core and having a diameter also equal to the diameter of said first layer of intermediate strands.

5. A wire rope as claimed in claim 1 comprising a first intermediate layer of seven strands, a second intermediate layer comprising a first set of seven strands of a qim tn ql l bs: diamsitq 91 said fir t; ayer igtgr sipgngls, and an mite;- layer of e ightee n s tranlds hayipg a diglget filj al sqiequgl t9, the diamete; of; said first layer mqr iam s and References Cited in the file of this patent N ED STATE ATE T x 69 5 2- RWbfiP :-r-+--.-.---- M 1918 FOREIGN PATENIS,

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