GB2214942A

GB2214942A - Method of making twisted wire articles

Info

Publication number: GB2214942A
Application number: GB8802270A
Authority: GB
Inventors: Vladimir Gavrilovich Khromov; Alexandr Petrovich Vetrov; Nikolai Ivanovich Drozdov; Viktor Ivanovich Lepin; Vasily Gavrilovich Nikitin; Yakov Abramovich Shifrin
Original assignee: SEVASTOPOL PRIBOROSTROIT INST; Sevastopolsky Priborostroitelny Institut
Current assignee: SEVASTOPOL PRIBOROSTROIT INST; Sevastopolsky Priborostroitelny Institut
Priority date: 1988-01-29
Filing date: 1988-02-02
Publication date: 1989-09-13
Anticipated expiration: 2008-02-02
Also published as: GB8802270D0; GB2214942B; FR2626904B1; DE3802631A1; FR2626904A1; DE3802631C2

Description

22.14942 METHOD OF MAKING TWISTED WIRE ARTICLES This invention relates to

the art of making twisted articles, and more particularly to a method of making twisted wire articles.

The invention can be used for making multi-strand cables, various wire ropes, and multi-stiand metal cords on-machines having rotating take-up pull mechanisms.

The invention can be used with the utmost advantage for making thin wire ropes for application in instruments and remote control systems, and for making metal cords to be used in izidustxial rubber products.

There is known a method of making twisted wire axticles in which a helical movement is imparted to a bunch of elongated elements.

This method comprises the steps of drawing a bunch of elongated elements from pay-off spools to a zone where a twisted wire article is formed. forming such an article by imparting to the bunch of elongated elements a forced helical movement (hereinafter referred to as twisting), and coiling the article rotating ai)out its own axis 6nto a take-up reel.

In zope-making machines for carrying out this method the pay-off spools can be mounted on a common fixed frame (wire feeding mechanism). This affords a variety of space-saying arrangements for the pay-off spools to be spaced at a minimum possible distance from the zone of formation of the twisted article. It is fox this reason that, as compared with widely known tubular machines. such machines have a wider range of production capacities at reduced overall size and weight, which is especially manifest during making thin multi-wire ropes and cables.

For coiling the axially rotatable twisted article onto the take-up reel the take-up mechanism must be rotated at a speed equal to the speed of rotation of the twisted article in the zone where it is formed. The rotor of the take-up mechanism includes a number of elements (such as a placer of the twisted article, replaceable take-up reel, finished twisted article) which are not amenable to accurate balancing and therefore sharply limit the admissible speed of rotation of the rotor. For this reason machines of this type can offer a relatively low capacity.

There is also known a method of making twisted wire articles by double twisting (cf., GBA,963,424).

This known method includes drawing a bunch of elon- gated elements from pay-off spools to the zone of formation of a twisted article, initial twisting of this article by imparting a forced helical movement to the bunch of elonEated elements, feeding the article to a take-up xeel about a curvilinear path having start and end thereof resting in one common axis such that by the end of its travel about the curvilinear path the twisted article changes the direction of movement to the opposite, repeated twisting of the article by imparting to a portion of the article present in the curvilinear path a rotational movement about the axis connecting the start and end of this path, and coiling the twisted article onto the take-up reel by providing a pull force. There with, the speed 4 1 of rotation of the part of the article in the zone of the curvilinear path is equal to the speed of rotation thereof at the zone of initial twisting.

In rope-twisting machines for carrying out this method a rotor is provided having guide elements for ensuring the travel of the twisted article about the curvilinear path. The take-up reel is mounted inside-the rotor on a carriage, which remains stationary during operation of the machine. In this manner the need for balancing the elements of the take-up mechanism is dispensed with resulting in that the maximum admissible rotational speed of the rotor can be higher. In aadition, this method allows to make a double twist for one revolution of the rotor. Such machines therefore have a higher output capacity.

However, in the course of repeated twisting the ini- tially twisted article is subjected to torsional strain. As a xe-sult, theelongated elements of the outer layers axe susceptible to stretching and those of the inner layers to compaction. In the case of making thin multilayer wire articles this operation causes breaking of the outer elongated elements accompanied by a tendency of the inner elements to appear at the surface and curve the longitudinal axis of the article. The use of this prior art method is therefore limited to making mainly one-layei (three-or fourstrand) twisted articles.

There is further known a method of makinE twisted wire articles (cf.,, GB, A,192099484) in which a bunch of elongated elements is drawn from pay-off spools to the zone where a twisted article is formed, the twisted article is formed 1 - 4 by imparting to the bunch of elongated elements a f orced helical movement, the article is fed to a take-up reel about a curvilinear path having start and end thereof resting in one common axis such that by the end of its travel about:the curvilinear path the twisted article chanSes- the direction of mDvement to the opposite, a portion of the article in the curvilinear path is rotated about the axis connecting the start and end of this path at half the speed of rotation of the article in the formation zone, and the article is wound onto the take-up reel by providing a pull force.

A rope-twisting machine fox cairying out this method includes two rotors. One rotor. acts to impart a forced helical movement to the twisted article in the zone where it is formed, whereas the second rotor rotates at half the speed of rotation of the first rotor and serves for pro ducing a curvilinear feeding path of the twisted article toward the take-up reel. The take-up reel is secured inside the second rotor on a fixed carriage.

In this method feeding of the twisted article about a curvilinear path by providing a pull f orce results in that the article fails to freely rotate about its own longi tudinal axis. Therefore, due to a difference in the rota tional speed of the two rotors the article will be half untwisted at the start of the curvilinear travel path to xetuxn to the initially twisted state at the end of this path. Such an arrangement prevents non-unif orm tension in vaxious wire layers in the finished ax.ticle.

However, as the twisted article travels along the curvilinear path in half-untwisted state, the slackened elongated elements, in this case wires, of the outer layer are displaced relative to the inner elements to lose the ini- tial helical pattern. This results in structural flaws normally not eliminated after the twisted article is returned to the initial state, which affects the quality of the article. The use of this method is therefore mainly confined to the production of multiple-conductor cables from such plastic materials as aluminium, copper and the like.

It is an object of the present invention to provide a method of making twisted wire articles. which could improve the quality of such articles.

The essence of the invention resides in that in a. method of making twisted wire articles comprising drawing a bunch of elongated elements from pay-off spools to a zone where the twisted article is formed, forming this twisted article by imparting a forced helical movement to the bunch of elongated elements, conveying this article to a take-up reel about a curvilinear path staxt and end of which rest in a common axis such that by the end of the movement along the curvilinear path the twisted article changes the direction of movement to the opposite, forcibly rotating a portion of the article about the axis connecting the start and end of this travel path at half the speed of rotation of the twisted article in the zone where it is formed, and coiling this article onto the take-up reel by providing a pull force. according to the invention, in the course of movement of the twisted article about the curvilinear path the pull force imparted thereto by the take-up reel is relieved by applying to the article a braking force immediately prior to coiling it onto the take-up reel. 5 Relieving the pull force applied to the twisted axtiCle in the zone of travel thereof along the curvilinear path in conjunction with forced helical movement of the article in the twisting zone affords spontaneous rotation of the article about its own axis thanks to its own torsional rigidity, which prevents untwisting (torsional strain) of the article and appearance of structural flaws to result in a substantial increase in the quality of the twisted article. Preferably, the magnitude of the braking fo ce applied to the twisted.article is selected within a range from 5Q75 to about 90% of the magnitude of the pull force produced by the take-up reel.

This ensures a sufficient tension of the twisted axticle for accurate coiling it onto the take-up reel while simultaneously reducing the pull force at the curvilinear path to a degree sufficient fox spontaneous rotation of the twisted article about its own axis.

It has been found experimentally that at a magnitude of the braking force substantially less than 50115 of the magnitude of the pull force applied to the article by the take-up reel rotation of the article about its own axis at the curvilinear path tends to become unstable, that is by virtue of friction in the zone where the axticle moves along the curvilinear path the rope is periodically pre- tl vented from rotation about its axis and subjected to torsional strain in a direction opposite to the direction of twisting. Therewith, the outer wires are slackened, displaced and lose the initial helical shape. As a result, structural flaws tend to periodically appear to affect the quality of the article. After the torsional strain of the article attains a magnitude at which the inner torsional moment equals the ultimate torsional moment produced by the forces of friction, the article starts to rotate about its own axis. The torsional strain and inner torsional moment tend to reduce. and the heretofore described process repeats.

At a magnitude of the braking force substantially greater than 96% of the pull force applied to the twisted article by the take-up reel rotation of the take-up reel driven through a friction coupling tends to become unstable.

C, This results in less accurate coiling of the twisted article onto the take-up reel.

At the point of transient slowing down of rotation or stopage of the take-up reel the rope tends to exhibit inadmissible slackening to result in the formation of a xotating loop at the outlet from the twisting zone. As it grows in size, the loop has a tendency of catching on the adjacent parts of the machine to cause breaking of the article and stop in machine operation.

In view of the aforedesexibed, the proposed method of making twisted wire articles allows to improve the quality of such articles.

The invention will become more fully apparent from a detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawinp-.,s, the sole Figure of which shows a diagrammatic view of a machine 5 for carrying out the proposed method.

- A bunch of elongated elements 1 is pulled from pay-off spools (not shown) mounted on a fixed feeding means 2 to a zone where a twisted article 3 is formed. The twisted article 3 is formed by imparting a forced helical motion to the bunch of elongated elements 1. This article 3 is delivexed to a take- up reel 4 about a curvilinear path having the start and end thereof resting in a common axis so that by the end of its travel along this path the twisted article 3 changes the direction of movement to the opposite.

Therewith, a section of the article 3 occupying the cuxvilinear path is rotated about the axis connecting the start and end of this path at a speed. which is half the speed of rotation of the article 3 in the zone where it is formed. The finished article 3 is wound onto the take-up reel 4 by providing a tension force. A braking foice is applied to the twisted article 3 immediately prior to winding it onto the reel 4.

The forced helical movement is imparted to the bunch of elongated elements 1 in the zone of forming the twisted article 3 by a belt or chain-type pull mechanism 5 rotating at a speed n. The curvilinear path of travel of the article 3 is produced by a spatially curved tubular guide element 6 of smoothly curved configuration capable of rotating at a speed n/2 in two supports 7. The take-up 11 1 reel 4 is secured on a carriage 8 suspended freely between the supports 7 in rolling bearings 9, this xeel 4 remaining stationary. A mecanism 10 is provided before the take-up reel 4 on the carriage 8 acting to apply a braking force to 5 the twisted article 3.

This mechanism 10 is of any known construction suitable for the purpose.

Application of a braking force to the twisted article immediately before winding it onto the take-up reel 4 re- duces the tension of the article 3 as it moves inside the tubular guide element 6 to an extent ensuring spontaneous rotation of the twisted article 3 about its own axis inside the tubular element 6 at a speed n/2. Thanks to such an arrangement the twisted article 3 is not subjected to torsional strain at the portion between the formation zone and take-up reel 4; whereby structural flaws are prevented to result in improved quality of the twisted article 3.

The magnitude of the braking force applied to the twisted article is selected depending on the mechanical properties of this article and characteristics of the rope-twisting machine to be within a range from 50% to about 967o of the tension force produced by the take-up reel. The upper range of the braking force is preferable, although this may be the cause of less accurate coiling of the article on the take-up reel due to periodic stops of the reel normally driven through a friction clutch. At the lower range of the braking force the spontaneous rotation of the article in'the curvilinear path becomes unstable to result in structural defects of the finished twisted 1 article.

Example 1

A single-twist wire rope was made by the proposed method from nineteen wires 0.03 mm in diameter. The method was carried out by a rope-twisting machine having a pull mechanism, a rotor with a tubular guide element accommodat-ing a take-up reel on a carriage and a braking means. The rotation speed of the pull mechanism was n = 4000 rp, m, whereas the rotation speed of the tubular guide element was n/2 = 2000 rpm. The rope was fabricated according to the proposed method. The magnitude of braking force was selected to be 5(Yo of the pull force produced by the take-up reel.

No structuxal flaws were in evidence in the thus made rope through its length. In the free state the rope failed to rotate about its axis and remained straight.

Example 2

The proposed method was used fox making a double-twist wire rope from seven preliminarily twisted strands each of which contained seven wires 0.07 mm in diameter.

The method was carried out at a xope-twisting machine similar to one described in Example 1.

The magnitude of braking force was selected to be 95% of the tension force produced by the take-up reel.

In the thus made rope no structural defects were in evidence throughout its length; in the free state the rope had no tendency to rotate around its own axis and remained straight.

11 1 Example 3

The proposed method was used for making a double-twist wire rope from seven strands each comprising three wires 0.15 mm in diameter.

The method was carried out at a rope-twisting machine substantially similar to one referred to in Example 1.

The magnitude of braking force was selected to be 80% of the force of tension produced by the take-up reel.

In the thus made rope no structural defects were in evidence throughout its length; in the free state the rope had no tendency to rotate about its own axis and remained straight.

The proposed method of making twisted wire articles can handle wire of various diameters and fabricate a range of rope structures.

The method of making twisted wire articles according to the invention is intended generally for fabricating thin wire ropes and metal cords.

This method opens the way to more efficient use of multistrand drawing machines and advanced wire twisting technology. In addition, the method ensures a reduction in the net cost of finished products by 6-12%.

9 1 t 12

Claims

Claims: -

1. A method of making twisted wire articles comprising drawing a bunch of elongated elements from pay-off spools to a zone where a twisted article is formed, forming such a twisted article by imparting to the bunch of elongated elements a forced helical movement, feeding said article to a take-up reel about a curvilinear path having start and end thereof resting in a common axis such that by the end of travel along this curvilinear path said twisted article changes the direction of movement to the opposite, forcibly rotating a portion of the twisted article at said curvilinear path about said axis connecting the start and end of this path at half the speed of rotation of said twisted article in the zone where it is formed. and coiling the article on the take-up reel by providing a pull force, whereas in the course of movement of the twisted article about said curvilinear travel path the pull force produced by the take-up reel is relieved from the twisted article by applying to it a braking force immediately prior to coiling the article onto the take-up reel.

2. A method of making twisted wire articles are claimed in claim 1. in which the magnitude of the braking force applied to the twisted article is selected within a range from 50% to about 90% of the magnitude of said tension force produced by the takeup reel.

1 1 b 13

3. A method of making a twisted wire article comprising the steps of:

twisting a plurality of elongate elements together to form the article; winding the finished article on a receiver means; and applying a braking force to the finished article prior to the article being wound on the receiver means.

4. Apparatus for making a twisted wire article comprising:

means for twisting a plurality of elongate elements together to form the article; means for receiving the finished article; means for driving the receiver means; braking means for applying a braking force to the finished article before the article is received by the receiver means.

5. A method of making twisted wire articles substantially as described in Examples for carrying it out and in the accompanying Figure of the drawings.

6. Apparatus for making a twisted wire article substantially as hereinbefore described with reference to the accompanying drawings.

Published 1989 atThe Patent0Mce, State House,66171 High HolboM LondonWO1R4TP. Further copies maybe obtainedfrom, The Patent0Ince.