US2385241A

US2385241A - Rope

Info

Publication number: US2385241A
Application number: US503998A
Authority: US
Inventors: White Edward Horace
Original assignee: WHITECROSS Co Ltd
Current assignee: WHITECROSS Co Ltd
Priority date: 1942-09-18
Filing date: 1943-09-27
Publication date: 1945-09-18
Anticipated expiration: 1962-09-18
Also published as: GB560868A

Description

Sept. 1s, 1945.

E. H. WHITE 2,385,241

RQPE

` Filed sept. A27,' 1945 2 sheets-sheet 1 E. H. WHITE Sep@ 18, 1945.

ROPE

2 Sheets-Sheet 2 Patented Sept. 18, 1945 ROPE Edward Horace White, Warrington, England, as-

signor to The Whitecross Company Limited, Warrington, England Application September 27, 1943, Serial No. 503,998 In Great Britain September 18, 1942 1 Claim.

This invention relates to the manufacture of ropes and the like, and more especially to the construction of the locked coil wire ropes suoli as used for colliery winding gear, sinking, or other ropes built on the concentric or multiple strandv pattern, more particularly of the nonrotating type. More particularly it relates to the method and apparatus of Patent No. 1,992,707,

according' to which the tendency of the core to locked coil wires or the like placed upon it whilst avoiding untwisting of the outer covering layer of the wires or the like after they have been laid upon the core.

In winding, and other ropes, made by the process referred to, successful results have been obtained in all cases, but in connection with the largest diameter of winding` ropes made of locked coil construction, it is found `that if the users do not re-set the ropes carefully to allow the selftightening properties to operate in a manner which would take up the, stretch in the outer wires, the outer covering may become loose on the core, and unevenness develop in waves, due to the slipping of the outer covering wires on the core, and consequent local overcrowding.. y

The object of the present` invention is to, provide for the overcoming of this diiiiculty, in-the case of non-twistingropes, ,especially those according to United StatesPatent N o. 1,992,707.`

After much experiment it has been found that this can be eiiectedby means of a supplementary layer in the outervcovering of the rope, and that it is particularly applicable to the case of large ropes, that is to say, ropes from 4a diameter of one and five eighthsor one and three' quarter inches upwards, the extra layer being' laid in a direction, that is to say tov a hand, similarto that of the outer layer of the cover and opposite to the hand orlay of thel layers of wires constituting the core. Several results arise from this mod,- ication of the method: of making ropes, one of which is that the re-setting of the rope from the end' at which the load is attached isonly required at comparatively long intervals', for instanceV at each re-capping, which has byustatute to take place at intervals of not more than six months,

the rope will automatically re-set itself if allowed to do so, and the stretch in the outer wires will be automatially taken up and the outer layers remain tight.

' Another valuable property in the new improved construction is that wire ropes of either right or left hand outer layers can be used on a winding drum which is arranged either right or left hand, whereas with other forms of locked coil or contra-lock windingropes, it is necessary for the rope to be designed with the outer layer either right or left hand to suit the particular lay-out, i. e. when looking towards the shaft from the opposite side of the drum, if the under-rope winds on, commencing at the right `on the drum and coiling towards the left, a rope of right hand lay must be usedcompare British Safety in Mines Research Board Paper, No. 41, Chapter XI, which reads: In certain cases the rope should be right hand or left hand lay, according to the direction inv which it coils on the drum; that is', when looking towards the shaft, from the opposite side of the drum, if the under rope winds on commencing on the right and coiling towards the left, a rope with a right hand lay should be used. This will give the rope a tendency to tighten up during use; if a left hand lay is used the tendency will be to untwis The outer covering of ropes according to the present invention may :be taken as comprising. two layers, namely, the outermost layer, and an additional or supplementary layer between the outermost layer and the core.

l The outermost layer should be of full-lock construction, but the supplementary layer which is laid to the same hand as the outer layer may be of full-lock, half-lock or segmental sections, or even a simple circular section.

This double outer layer of section wires is not simply a duplication from the aspect of using two layers instead of one, but it has a functional effect:

Firstly, from the fact that two layers in a concentric cable laid up in the same direction have a much greater area of contact than in the case of crossed layers, and therefore the outer layer is not inclined to slide upon the inner layer. l

This is illustrated in a diagram referred to below, and is borne out in practice by the fact that the outermost layer has a strong gripping eifect on the second layer, so much so that even when the usual end clamps or servings are removed there is very little tendency to slip or spring apart.

Secondly, with the two outer layers of wires The invention consists in a non-twisting rope consisting of a core comprising a number of layers of wire wound to one hand, two layers of wires disposed around this core, these layers both being laid to the same hand but to the opposite hand from that of the core, and in which there is a twist in all the layers of the core with respect to the rst or inner layer of the two covering layers, the sectional areas of the core layers multiplied by their respective distances from the centre being not less than the sectional area of the two outer layers multiplied by their respective distances from the central axis of the rope.

Referring to the accompanying diagrammatic drawings:

Figure 1 is an end elevation, and

Figure 2 a side elevation, with parts of the various layers removed, to illustrate one form of the present invention:

Figures 3 and 4 are views similar to Figures 1 and 2, but of a modied form of the present invention: f

Figures 5 and 6 are diagrams to assist in eX- plaining untwisting tendencies or resultant torque due to the load acting on the various layers of a rope.

Referring to Figures 1 and 2, the core consists of the parts of the rope marked a, comprising a number of layers otwires of circular or what may be termed of rail section, with voids or filled intersticesy indicated by b. The outermost layer indicated by e is formed of wires of full-lock section, laid to a hand opposite from that of the core. Between this outermost layer e and the core a, a supplementary cover layer f is disposed, wound to a hand opposite from that in which the core wires a and the outermost covering wires e are wound. The part broken away from Figure 2 from the wires of the outermost covering e shows, that there is a very large area of contact between the wires e and the. wires f, which in practice results in a strong gripping effect, as referred to above. t

, In the form of the invention shown in Figures 3 and 4, the core wires a are similar to those in Figures 1 and 2, and the same applies to the wires e constituting the outermost layer of the cover. The supplementary layer of the cover ishere formed bywirestgwhich are of circular section, but as in Figures 1 and 2, the wires a and e are wound to opposite hands, whereas the wirese and g are wound to the same hand. It is, however, preferred to use non-circular wires for the supplementary layer of the cover, in accordance with Figures 3 and 4, rather than wires of circular cross section, as illustrated in Figures 3 and 4, for circular cross section wires may tend to have a certain amount of cutting eiect. v

Wire ropes according to Figures 1 and 2 or3 and 4 may conveniently be made by means of apparatus as described in United States Patent No. 1,992,707, or in either of British Specifications Nos. 388788 or 493077.

Referring now to Figures 5 and 6, a measure of untwisting tendency, or resultant torque due to the load acting on the various layers of the rope may be obtained from the sectional area of each layer multiplied by the distance of its centre-line from the central axis of the rope.

Referring to the diagram Figure 5 showing the outside of a concentric rope or strand, in which the Wires are laid at an angle a to AC, the central axis, if it be imagined that one wire be taken and rolled off into a plane for the length of one complete lay, then in Figure 6 this is represented by CB, W representing the load acting along the central axis, T representing the tension in the wires due to this load at an angle of lay a.

The closing resultant of the triangle of force is represented by AB acting at right angles to the central axis.

From the simple triangle of forces, the torque: load multiplied by tangent of angle of lay (from diagram AB=W tan a) and this, divided over the layers of the rope according to their sectional area multiplied by the distance of the centre-line of each layer from the central axis of the rope, would enable the calculation to `be made as to the relative balance between the two outer layers laid one hand, and the core layers laid to the other hand.

Assuming the sectional area` of the various core layers, starting from the centre of the rope to be Al, A2, A3, and so on, acting at distances RI, R2, R3, and so on from the central axis of the rope, and the sectional area of the two outer layers to be AO.I and AO.2 respectively, acting at distances of ROJ'and RO.2 from the central axis of the rope, then in general the design of rope should be such that whatever the sections used in the various layers, the torque resulting from the sectional areas of the core layers multiplied by their respective distances from the centre, should not be less than the torque resulting from the sectional area of the two outer layers multiplied by their respective distances from the central -axis of the rope,V i. e.,

(AI XRD-l-(AZXRZ) +(An Rn) The over-balancing eiect which keeps the outer layers tight will then be provided by the overtwistput into the core, the amount of which is capable of calculation, and easily ascertained by trial, as is mentioned in the patent specification referred to above.

The computation just given assumes that the angle of lay is constant throughout and some small adjustment is required where a wide variation occurs between the angles of lay inldiierent layers. i -General The present invention is best applied to those cases Where the outer layer is of full-lock construction only, and to ropes of one and five eighths inches diameter and larger, in which the total sectional area of the wires of the two outer layers which is required for practicalV working conditions can be so designed that the untwisting moment of thesetwo layers remains less than the untwisting moment of the core, plus overd twist, that is, plus the additional untwisting moment due to the overtwist which is put in to the core, whilst the supplementary layer to the opposite hand is laid around it. The overtwist is put into the core whilst the supplementary layer is being laid round it. The outermost layer of full-lock Wires is then laid on.

In ropes of a smaller diameter than one and ve eighths inches the sectional area of the wires of the outer layers may have to be so reduced in order to give effect to this requirement that they would not be heavy enough to provide the necessary wearing surface, and in any case the necessity for special treatment in the construction of ropes of less than one and ve eighths inches diameter does not arise, to such an important degree.

A property observed in ropes made by the new modified consruction is that a straight rope may be obtained, with no tendency to curl at any part of its length, whereas in new ropes of either the original contra-lock of other locked coil constructions, a set or curl can be observed when the rope is cut at any point, or released from tension after pulling off from its reel. This apparently means that the internal stresses in the complete structure under the modied construction are either absent, or more perfectly balanced than with the other constructions referred to, in which the set or curl indicates some unreleased stresses remaining, and in addition this property renders the ropes easier to handle through slightly greater flexibility and freedom from tendency to kink.

I claim:

A non-twisting rope consisting of a core comprising a number of layers of wire wound to one hand, two layers of wires disposed around this core, these layers both being laid to the same hand but to the opposite hand from that of the core, and in which there is a twist in all the layers of the core with respect to the rst or inner layer of the two covering layers, the sectional areas of the core layers multiplied by their respective distances from the centre being not less than the sectional area of the two outer layers multiplied by their respective distances from the central axis of the rope.

EDWARD HORACE WHITE.