US2524439A - Method and apparatus for treating wire products - Google Patents

Description

Oct. 3, 1950 R; D. GREEN METHOD AND APPARATUS FOR TREATING WIRE PRODUCTS Filed Dec. 31, 1946 2 Sheets-Sheet 1 INVENTOR Plum/P0 Dun-NE Gees/v ATTORNEY Oct. 3, 1950 R. D. GREEN 2,524,439 METHOD AND APPARATUS FOR TREATING WIRE PRODUCTS Filed Dec. 31, 1946 2 Sheets-Sheet 2 INVENTOR [PICA/6RD Dw/vs GREEN:

' A ORNEY- Patented Oct. 3 1950 METHOD AND APPARATUS FOR TREATING WIRE PRODUCTS Richard Duane Green,

Trenton, N. J., assignor to John A. Roeblings Sons Company, Trenton, N. J., a corporation of New Jersey Application December 31, 1946, Serial No. 719,420

11 Claims. 1 y This invention relates to the treatment of wire rope, strand, cable and the like to improve the physical propertiesof such products, and more particularly relates to a method and apparatus for treating such products under tension.

Various procedures have been suggested heretofore for pie-stretching wire rope and particularly wire rope designed for uses such as elevator cables. Although some rather exaggerated claims have been made, such procedures as have been adopted heretofore have attempted to re move what is known as the constructional stretch from the rope, or, in other words, to produce an elongation of the rope approximately equal to that which takes place after an untreated rope has been in actual use for some time.

Such treatments by the application of tension alone have had little or no efiect on other physical properties of the rope such as its fatigue resistance and its ultimate strength. Also, suchtreatments have involved either expensive extra equipment, or extra equipment plus an entirely separate operation, with an attendant substantial increase in the cost of manufacturing the rope.

One object of this invention is to provide a treatment for wire strand, cable, rope and the like which is simple and relatively inexpensive to perform and which produces many improvements in the physical properties of the product.

Another object is the provision of a method and apparatus for improving the physical properties of such materials by subjecting them under controlled conditions to tension in excess of the proportional limit of the material being treated.

A further object of the invention is the provision of method and apparatus for treating such materials by flexing them under tension in such a manner that at least a majority of the individualwires of the product are stretched sufficiently to produce permanent set.

Another object of this invention is the provision of method and apparatus for treating wire rope, and particularly lang lay wire rope, by subjecting it to a high degree of tension while the rope is on a pullut mechanism serving to pull the wire rope thr zigh the closing die.

A further object is to manufacture wire rope, strand, cable and the like by substituting for an ordinary pull-out mechanism in the stranding or closing machine, a pull-out in which the drums have portions of different diameters to subject the product to the required amount of tension.

Other objects and advantages will be explained and will be apparent from the following description of the invention in connection with the drawings, in which:

Fig. 1 is a somewhat diagrammatic side elevational view of a special pull-out mechanism in accordance with this invention associated with a closing die and take-up reel.

Fig. 2 is a top plan view of the apparatus shown in Fig. 1.

Fig. 3 is a radial sectional view on a still larger scale taken through the outer portion of one of the differential diameter drums in the pull-out mechanism shown in Fig. 3. 1

Fig. 4 is a fragmentary plan view of the tensioning mechanism on a larger scale than Fig. 1 to show the manner in which a wire rope is subjected to tension and flexing.

Fig. 5 is a fragmentary longitudinal sectional view on a larger scale through the tensioning mechanism.

In accordance with my invention a structure composed of individual wires twisted together, such as wire strand, cable, rope and the like, is subjected to a high degree of tension and preferably a tension high enough to produce an actual permanent set in most, if not all, of the individual wires making up the structure. While the structure is under this tension, it is preferably subjected to repeated flexing or working. For best results, the amount of tension should be in excess of the proportional limit of the product being treated, and preferably in excess of of the ultimate or breaking strength of such product. For practical purposes, the proportional limit of the product treated may be considered to be the unit stress on a stress-strain diagram at which the rate of deformation is 50% greater than the minimum rate of deformation.

I have found that such a high degree of tension, particularly when it is accompanied by flexing or working under tension, produces very beneficial improvements in the physical properties of the structure. It is apparent, of course, that such a treatment removes what is known as the constructional stretch or, in other words, that part of the elongation which results from the compacting of the structure of a wire rope or strand. In addition to removing the constructional stretch, however, this treatment, particularly as applied in accordance with the procedure I prefer as described below, produces a final product that has a substantially higher fatigue resistance; that has a somewhat higher ultimate strength; and that is extremely uniform in its properties throughout its entire length. Such uniformity makes it much easier to predict what a long length of strand or rope will do in actual performance since much greater reliance can be placed upon results obtained from physical tests of a short length of the material.

My invention has still further advantages when applied to the treatment of particular products such as lang lay rope, a material that is very diiflcult and expensive to make satisfactorily. At present, the manufacture of high quality lang lay rope requires special precautions in its manufacture, such as the use of special stranding and closing machines to put back-twist into the individual wires as the strand is made, or to regulate carefully the twist that is given to the strands as they are fed to a closing die in a closing machine. For most purposes, stranding and closing machines that operate at relatively slow speeds must be used in order to produce a high quality lang lay rope, and such procedures all add to its cost.

The process of my invention may be applied to a finished lang lay rope made without taking these special precautions and makes it possible to produce a high quality lang lay rope that is even less cranky than usual, as well as having the other improved properties mentioned above. This is particularly important economically because the process of my invention may be applied, particularly in its preferred form, to the manufacture of wire rope without using any additional step or extra equipment in the entire process.

The preferred apparatus for carrying out my invention is illustrated in the drawings as applied, for example to the manufacture of wire rope. The strands II) in a closing machine are fed in any suitable manner to a closing die II. Instead of using the customary pull-out mechanism to pull the wire rope I2 through the closing die, I employ a pair of drums l3 and I4 spaced from each other in the usual manner but having on each drum, sections I5 of one diameter and sections I6 of a larger diameter. These drums may be mounted upon suitable shafts I1 and I8 and driven though gears I9 and by means of the small pinion gear 2| associated with the motor 22. As will be apparent, any source of power may be used to drive these drums so that they are rotated in the same direction at the same speed. If desired, the bearings 23, 24 for the shafts I! and I8 respectively may be rigidly held apart by an adjustable bar 'or rod 25.

The Wire rope I2 from the closing die II is passed for several Wraps or turns around the smaller diameter sections I5 of the two drums I3 and I4. In accordance with well known practice, the sections I5 and I6 of these drums are preferably provided with annular grooves 26 of proper diameter to receive the wire rope I2.

The wire rope then passes from the last groove in the sections I5 to the first groove in the sections I6 and may then be passed for several turns around the larger diameter sections I6 of the two drums. The rope moves from the drums I3 and II to a take-up reel 21 mounted on a suitable standard 28 and preferably driven by a motor or other means (not shown) connected to the shaft 29.

It will be apparent that the grooves in the larger diameter sections I6 of the two drums travel at a higher peripheral speed than the grooves in the smaller diameter sections I5. Thus, in a given number of rotations, the rope on the drum sections I6 will be traveling a greater distance than the rope on the drum sections I 5. This creates a high degree of tension in the rope on the two drums. As a pract c l matter, the drums can be arranged with the proper differential in diameters between the sections 15 and. I6 and the proper number of wraps or turns of the rope about each section to produce any desired degree of tension in the rope.

It has been found that the tension of the rope on the smaller sections l5 increases as the rope gets closer to the inside groove from which it transfers to the first groove on the larger diameter sections I6. The peak tension is applied to the rope passing from the last groove in the smaller diameter section I5 to the first groove in the larger diameter section I6. Thereafter, the tension in each successive turn of the rope around the larger diameter sections I6 decreases until the point is reached at which the rope passes to the take-up reel. A certain amount of slippage as well as creepage of the rope on the drums takes place which accounts for this tension variation.

If relatively few turns of the rope are used about each of the sections of the differential diameter drums, it may be desirable to have a greater take-up tension applied by the reel 21 than would normally be used. This is needed to prevent undue slippage which might result in the application of a much lower peak tension to the rope than is desired. For most practical purposes, the back tension applied by the closing die I I is entirely adequate to prevent undue slippage of the rope on the smaller diameter sections I5.

Care must be exercised in choosing the diameters to be used for the sections I5 and I6 and in the selection of the number of turns or wraps about each section of the drum, as well as in the amounts of back tension applied to the rope on. the drums to provide sufficient tension but still avoid the application of such a high tension as will produce failure or rupturing of the rope. The rope is also being flexed repeatedly while it is under tension by reason of its passage along successively straight and curved paths. This flexing produces a very beneficial actual working of the rope or similar structure as well as of the materials comprising the structure while they are in the plastic range, 1. e., under a tension in excess of the proportional limit.

It will be seen that the differential pull-out mechanism of my invention may be very simply substituted for an ordinary pull-out mechanism customarily used on a stranding or closing machine, so that the use of my invention does not actually involve additional apparatus, but does supply an additional and very beneficial processing of the product being treated. From the economic point of view, the strand, cable or rope may be made in accordance with my invention at low cost without the necessity of using either special preliminary treatments or expensive after treatments of the product. At the same time, the final product, probably because of the manner in which it is subjected to the tension as well as the amount of tension applied, has its physical properties improved to a very surprising degree.

While one form of the invention has been described in connection with the example illustrated in the drawings, it will be apparent to those skilled in the art that many variations may be made in the apparatus as long as the product is subjected to the proper amount of tension alone or to a combination of such tension with flexing or working to produce the desired improvements in physical properties.

2. A process of treating wire strand or rope to produce a greater resistance to fatigue and higher ultimate strength which comprises moving such material alternately through straight and curved paths and subjecting successive short lengths of the moving material for short periods of time to tension of at least about 70% of the ultimate strength of the material but less than said ultimate strengt 3. A process of treating wire rope to improve its uniformity and increase its strength after fatigue by flexing the rope while under tension which comprises moving said rope through a plurality of alternate straight and curved paths, in-

reached, said maximum tension than the proportional limit for said rope.

4. A process of treating lang lay wire rope to increase its strength after fatigue and ultimate strength which comprises moving said rope through a plurality of alternate straight and curved paths, increasing the tension on such rope at successive straight paths until a maximum tension is reached, and thereafter relieving said tension gradually in successive stages, said maximum tension being substantially higher than the proportional limit for said rope.

'5. In a process of making wire strand, wire rope and the like, the steps of passing the material around a plurality of driven drums having of different diameters, moving the material after several turns from the smaller diameter portions of said drums to the largest diameter portions thereof, and maintaining tension on the material issuing from said drums, the diiference in diameters of said portions and said issuing tension being suflicient to apply a maximum tension above the proportional limit of the material but insufiicient to rupture the material.

6. In apparatus for making wire strand, rope and the like, a pull-out device comprising a pair of capstans havin portions to receive the prodnot from a forming die, and other portions opposite each other traveling at a higher peripheral speed that receive the product from said first mentioned portions whereby the product is subjected to increased tension as it passes to said second mentioned portions.

7. In apparatus for making wire strand, rope and the like, a pull-out device comprising a pair of drums, each drum having cylindrical portions of different diameter, and means for rotating said drums at the same speed in the same direction, said portions of smaller diameter being arranged to receive the product from a forming die and said portions of larger diameter being arranged to receive the product from said portions of smaller diameter whereby the product is subjected to tension which reaches a maximum as the product moves from said smaller to said larger diameter portion.

- vent undue slippage of 8. Apparatus for treating a twisted wire product to improve its physical properties which comto maintain sufficient tension on the product issuing from said larger diameter portions to prethe product on the drums, the diiference in diameter of said portions being suflicient to create tension in the product above its proportional limit but below its breaking limit.

9. In apparatus for makin wire strand, wire rope and similar twisted wire products, the combination of a closing die for forming the twisted product, and a p -out device for pulling the of at least 70% of the ultimate strength or the rope but less than its breaking strength.

RICHARD DUANE GREEN. REFERENCES CIT The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 286,258 Brownell Oct. 9, 1883 1,692,505 oilmann Nov. 20, 1928 1,955,540 Ellis et a1. Apr. 17, 193:4 2,087,606 Oppenlaender et al. July 20, 1937 2,372,627 Goggin et a1 Mar. 27, 194 5 2,389,878 Symmes Nov. 27, 1945

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