US3771304A

US3771304A - Twisting motion and process for producing wire cords

Info

Publication number: US3771304A
Application number: US00235273A
Authority: US
Inventors: K Taketomi; T Katsumata; N Matsushima; M Yoneji
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 1971-03-16
Filing date: 1972-03-16
Publication date: 1973-11-13
Anticipated expiration: 1990-11-13

Abstract

This invention relates to twisting machine and process for producing wire cords particularly suitable for use in reinforcement of vehicle tires and other various articles of rubber or plastics. An over twister is provided between a rotating double twister adapted to twist together a plurality of wire elements, including pre-twisted wires, and a stationary take up means. The over twister consists of rollers turning about a path of travel of the twisted wire cord in the counter direction to the rotation of the double twister at a speed of revolution sufficient so as to convert at least part of the elastic strain in the wire elements which has been imparted by the double twister, to a corresponding permanent torsional strain, thereby improving the straightness of the finished wire cord and minimizing the tendency of the wire cord to become untwisted and curled as well as enabling higher speed production of twisted wire cords.

Description

United States Patent [1 1 Taketomi et al.

[ Nov. 13, 1973 1 1 TWISTING MOTION AND PROCESS FOR PRODUCING WIRE CORDS [75] Inventors: Kameo Taketomi; Tomoaki Katsumata; Norihisa Matsushima;

Masaari Yoneji, all of ltami, Japan [73 I Assignee: Sumitomo Electric Industries, Ltd.,

Nigashi-ku, Osaka, Japan [22] Filed: Mar. 16, 1972 [21] Appl. No.: 235,273 [30] Foreign Application Priority Data March 16, 1971 Japan ..46/14103 [52] US. Cl 57/58.57, 57/5859, 57/166 [51] Int. Cl. D07b 3/00, D07b 7/08, D02g 3/48 [58] Field of Search 57/58.3, 58.32, 58.49, 57/58.52, 58.57, 58.59, 58.7, 58.72, 58.83,

Primary Examiner-Donald E. Watkins Attorney-Richard C. Sughrue et a1.

[57] ABSTRACT This invention relates to twisting machine and process for producing wire cords particularly suitable for use in reinforcement of vehicle tires and other various articles of rubber or plastics. An over twister is provided between a rotating double twister adapted to twist together a plurality of wire elements, including pretwisted wires, and a stationary take up means. The over twister consists of rollers turning about a path of travel of the twisted wire cord in the counter direction to the rotation of the double twister at a speed of revolution sufficient so as to convert at least part of the elastic strain in the wire elements which has been imparted by the double twister, to a corresponding permanent torsional strain, thereby improving the straightness of the finished wire cord and minimizing the tendency of the wire cord to become untwisted and curled as well as enabling higher speed production of twisted wire cords.

5 Claims, 5 Drawing Figures PATENTEDHUV 13 I975 3,771; 304' SHEET 10F 3 FIG. I

PATENTED NEW 13 I975 SHEET 2 OF 3 FIG. 2

ELASTIC STRAIN wmmmkm 20 mmO.

NUMBER OF TWIST PER UNIT LENGTH IOOO ZOQO 3000 NUMBER 8F REVOLUTI N 5 5 POSI- E POSITION 5 TION 8P l 2 POSITION B o FIG. 3

TWISTING RATIO OF OVER TWISTER PATENTEDHUV 13 I975 SHEET 3 OF 3 FIG. 4

TWISTING MOTION AND PROCESS FOR PRODUCING WIRE CORDS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a twisting machine and process for producing wire cords particularly suitable for use in reinforcement of vehicle tires and other articles of rubber or plastics.

2. Description of the Prior Art A double twister for producing electric conductors or similar materials is well known which includes supply reels mounted on a frame for supplying a plurality of individual wire elements which are led through a rotating arcuate guide to form a balloon and thus imparted with a double twist per revolution of the arcuate guide and then taken up as a twisted wire cord on a take-up means provided on a floating cradle within the rotating arcuate guide.

However, when making steel cord and other high elasticity materials such a double twister system results in a significant amount of residual torsional stress in the twisted wire cord which tends to untwist or curl when unrestrained.

To eliminate this problem, it would be possible to opcrate the double twister at a considerably higher speed than that required for imparting the desired amount of actual twist to the wire elements so that an additional amount of twist corresponding to the elastic strain is imparted to the wire elements and then the excess twist is diminished at or after the taking-up stage of the finished wire cord by any kind of untwisting method.

Such higher speed rotation and untwisting action can lead to a considerable reduction in useful life of the bearings and other structural elements used in the double twister and the possibility of the wire cord breaking will be increased.

SUMMARY OF THE INVENTION It is a primary object of the present invention to provide a new and improved twisting machine for producing wire cords which overcomes the above-mentioned problems and wherein the residual elastic strain in the finished wire cord is effectively controlled and reduced without need for exceptionally high speed rotation of the double twister.

In one aspect of the invention, there is provided a wire twisting machine which comprises an over twister including rollers disposed between a double twister rotating about a floating cradle to form a balloon of a plurality of wire elements including pre-twisted wires, drawn from the supply reels, and a stationary take-up means, said rollers being adapted to turn in a direction counter to the rotation of the double twister about a path of travel of the twisted wire cord passing through the machine at a speed of revolution sufficient to convert at least part of the elastic strain which has been imparted to the wire cord by the double twister, to a corresponding permanent torsional strain.

The above and other objects, features and advantages of the invention will become apparent by the following description taken in conjunction with the accompanying drawings wherein one practical form of the present invention is shown only by way of example and not limitation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a preferred embodiment of the twisting machine for producing wire cords in accordance with the invention;

FIG. 2 is a diagram showing the torsion stress imposed to the wire cord 31 by the machine of FIG. 1;

FIG. 3 is a diagram showing the relation between the twisting ratio of the over twister used in the twisting machine of the invention and the number of residual twists per unit length of the finished wire cord;

FIG. 4 is a side elevational view showing the wire tension adjusting device incorporated upon each of the individual supply reels 6 used in the twisting machine of FIG. 1; and

FIG. 5 is a perspective view of the break detector means used in the twisting machine of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, and particularly to FIG. 1, the twisting machine of the invention includes an over twister 4 provided between a double twister 1 and a take-up means 2, the over twister consisting of rollers 41 adapted to turn in a different direction to the rotation of the double twister 1 about the path of travel of the twisted wire cord 31 at a speed of revolution sufficient to convert the elastic strain imposed on the individual wire elements 3 forming the wire cord 31 by the double twister 1 to a corresponding permanent strain.

As shown in FIG. 1, the double twister 1 includes a plurality of supply reels 6 supported by a floating cradle 5. Each of the supply reels 6 incorporates a wire tension adjusting device having a configuration to be described later with reference to FIG. 4.

The double twister further includes a pair of spaced

rotary disc frames

8a and 8b rotated at the same speed of revolution by a common drive motor 7. The twisted wire cord 31 is led from one of the rotating frames 8a to the other rotating frame 8b with or without assistance of a rotating arcuate guide member 15 which rotates around the floating cradle 5 is such a manner that the core 31 forms a balloon between the

rotating frames

8a and 8b.

The floating cradle 5 is supported by

stub shafts

13a and 13b joumaled in

ball bearings

14a and 14b within the

rotating frames

8a and 8b. Thus, the floating cradle 5 will remain stationary even when the

frames

8a and 8b rotate.

The individual metallic wire elements 3 drawn from the supply reels are passed separately through the holes of a lay plate 9 and into the opening of a die 10 in which the individual wire elements are gathered to form a single compact bundle.

While the individual wire elements are drawn separately from the respective supply reels 6 in the illustrated embodiment, it should be understood that a number of individual wire elements 3 may be drawn from a single supply reel.

The over twister 4 which consists of the rollers 41 rotating about the path of travel of the twisted wire cord 31 in the counter direction to the rotation of the

rotating frames

8a and 8b of the double twister l is located downstream of the double twister 1. The rotational speed of the over twister 4 is controlled to impart to the twisted wire cord 31 an amount of additional twist sufficient to partially or wholly convert the elastic strain which has been imparted to the individual wire elements 3 by the double twister 1, to a corresponding permanent strain so that the finished wire cord 31 coiled on the take-up means will have no elastic strain (residual torsion stress).

A speed controller 11 is incorporated in the drive means of the over twister 4 for altering the speed of rotation of the over twister because the amount of elastic strain present in the wire elements varys depending upon the diameter, strength and tension of the individual wire elements 3 comprising the twisted wire cord 31.

It is believed, however, that the speed controller 11 may be omitted in situations where it is desired to twist wire elements having identical size and properties at all times.

The two rollers 41 of the over twister 4 are mounted in staggered relation on the opposite sides of the effective path of travel of the twisted wire cord so that the twisted wire cord 31 is passed over these rollers 41 to a figure eight pattern.

As will be understood by those skilled in the art, other over twister configurations providing a similar result may be employed instead of the present two roller arrangement. For example, only a single roller 41 could be employed.

A take-up capstan 12 is provided between the over twister 4 and the take-up reel 2 for advancing the twisted wire cord. During the travel from the over twister to the take-up reel 2, the elastic strain present in the individual wire elements of the wire cord 31 is relieved by virtue of the excess counter twist imparted by the over twister and the finished wire cord is coiled on the take-up reel 2 without any elastic strain or in otherwise good-controlled condition.

Automatic operation of the speed controller of the over twister may be provided by the use of a torsion senser roll (not shown) located between the capstan l3 and the take-up reel 2 for detecting the amount of the torsion stress remaining in the wire cord 31.

Referring now to FIG. 5, there is shown detailed configuration of a break detector means 16 which is located between the two take-up rolls 12 over which the wire cord runs in parallel side-by-side loops or turns. As shown in this figure, the break detector means comprises a U-shaped insulating member having an open end and which extends across the full width of the parallel loop web of the twisted wire cord. The inner surface of the U-shaped insulating member is entirely covered by an electric conductive plate 18, such as a copper plate, so that a sufficient clearance between the wire cord loops and the electric conductive plate 18 is maintained during normal operating conditions.

Upon the occurrence of a break in the twisted wire cord 31 the end of the broken wire element springs out beyond the outer surface of the twisted wire cord 31 so that it will contact with the electric conductive plate 18 as the portion of the wire cord having the break passes through the break detector means 16. Any break in the individual wire elements of the wire cord is thus electrically detected in an easy and reliable manner.

It may be preferable that the break detector means is operably connected to the drive means of the twisting machine in order to automatically stop the machine operation upon the detection of a break.

Since the wire elements used to form certain types of wire cords, such as steel cords, are generally extremely thin and small in diameter with little lengthwise elongation capability, the breaking or tearing of the individual wire elements occurs frequently during high speed operation of the twisting machine and cannot be easily detected, particularly after the wire elements have been twisted together.

In accordance with the invention, however, accurate and reliable detection of any break in the individual wire elements is achieved by the above break detector means which extends over a plurality of spaced points of the twisted wire cord running in side-by-side loops.

Such accurate and reliable break detection results in substantial material saving and more efficient and increased out put production.

Assuming that the double twister l is rotating at 1,500 rpm. and a number of individual wire elements are drawn from the supply reels 6 through the respective holes of the lay plate 9 and through the opening of the die 10 as a single bundle and then passed in the form of a balloon between the

frames

8a and 8b rotated by the drive motor 7, the bundle of individual wire elements is twisted by the 1,500 rpm. rotation of the rotating frame 8a and thereafter additionally twisted by the 1,500 rpm. rotation of the rotating frame 8b. The total amount of twisting imparted to the wire elements by the two rotating frames is that of 3,000 rpm. rotation.

If the wire cord were directly taken up by the take-up reel, the finished wire cord would contain substantial elastic strain which creates a tendency for the finished wire cord to spring back and become untwisted and curled even when the wire cord is rewound is such a manner as to remove the elastic strain, whereupon the finished wire cord does not have the desired amount of twist.

By contrast, in accordance with the invention, the elastic strain, such as that corresponding to a 1,000 r.p.m. speed of revolution, in the individual wire elements of the twisted wire cord 3 can be partially or wholly removed by the over twister 4 which is rotated in a direction counter to the revolution of the double twister 1 at 1,000 rpm. The total amount of twist imparted to the wire cord by the double twister l and the over twister 4 is that of a 4,000 rpm. speed of rotation but the twisted wire cord is untwisted by the residual elastic strain corresponding to a 1,000 rpm. speed of revolution as it passes from the over twister 4 to the take-up capstan 12 so that a finished wire cord provided with twist exactly corresponding to a 3,000 rpm. speed of rotation will be taken up on the take-up reel without any residual torsion stress.

FIG. 2 is a diagram showing the relation between the torsion stress imparted to the wire cord passing from the supply reels 6 to the take-up reel 2 and the twisting number per unit length of the twisted wire cord.

Example: I

Four steel wire elements (AISI C1070, tensile strength 285 kg/mm) were twisted together with a twisting pitch of 9.5 mm to form a twisted cord. FIG. 3 shows the relation between the twisting ratio of the over twister and the twisting number per unit length of the twisted wire cord.

The twisting ratio R in the over twister is defined by:

R percent (B/2A B) X 100 wherein A is the rotational speed of the double twister in r.p.m.

The residual twisting number is determined by the number of twists remaining in each 1 M of the twisted wire cord taken up on the reel and algebraic signs and designate the directions of the twists.

While the optimum twisting ratio of the over twister depends upon the size, strength, strand lay length, quality of the wire elements used and the amount of twist in the double twister as well as the nature of subsequent treatment processes to take place on the wire cord, a twisting ratio less than 60 percent, preferably of to percent, has been found from various tests to be satisfactory.

The torsion stress in the individual wire elements of the twisted wire cords is also influenced by the characteristics of the wire elements and by non-uniformity in tension of the individual wire elements as they are drawn from the supply reels. The non-uniform tension leads to non-uniformity in wire twisting effect which adversely affects the straightness of the twisted wire cord. Moreover, the non-uniform tension would sometimes result in breaks in the individual wire elements being twisted.

In order to eliminate this problem, a tension adjusting device is incorporated upon each of the supply reels 6, having a configuration shown in FIG. 4. In this figure, the supply reel 6 with a winding of the metallic wire element 3 is mounted within the floating cradle 5 by means of a reel shaft 19.

A braking wheel 20, which has an annular groove for receiving a tension belt,or rope, 21 extending around the braking wheel, is fixedly connected to one of the end flanges of the supply reel 6 for rotation with the supply reel 6 on the reel shaft 19. Urged and maintained in sliding contact with the outermost layer 30 of the winding of wire element 3 is a friction roller 29 which is supported by an arm 22 pivoted at the other end 34 on the floating cradle.

A coil spring 24 has one end pivotally connected to the arm 22 at 28 and the other end connected to one arm 27 of an L-shaped member 23 which is pivotally mounted on the floating cradle at 32. The effective length of the coils spring can be varied and adjusted by adjustable lock nuts engaging on a threaded rod 33.

The other arm 26 of the L-shaped member is connected to a free end of a tension belt 21 extending around and engaging in a portion of the annular groove of the braking wheel 20 and fixedly connected to the floating cradle at the other end 25.

It should be noted that the

pivots

25, 34 and 32 are located within the floating cradle radially outward of the supply reel 6.

With the wire tension adjusting device above described, as the diameter and quantity of the winding 30 of wire element 3 on the supply reel 6 decrease because of withdrawal and supply of the wire element 3 to the twister, the arm 22 is allowed to turn in the direction of the arrow in FIG. 4 so that the pulling force exerted to the tension belt 21 by the linkage including the arm 22, the spring 24 and the L-shaped member 23 is correspondingly diminished, thereby avoiding an increase of tension in the wire element with the decrease in diameter of the winding on the supply reel so as to maintain a substantially uniform tension in the wire element drawn from the reel. Thus, the wire tension adjusting device facilitates uniform and constant twisting effect and, accordingly, improves the straightness of the finished wire cord as well as avoiding breakage during the twisting process.

From the foregoing, it should be readily understood that the amount of permanent twist in the finished wire cord can be readily varied and controlled by untwisting at least part of the elastic strain imparted to the wire cord by the double twister, using the over twister 4 which imparts a certain amount of torsion stress in the counter direction to the twisting action of the double twister whereby the wire cord will be untwisted to remove or reduce the residual elastic strain before the wire cord is coiled on the take-up reel 2.

The finished wire cord is a twisted wire element combination resulting from elastic torsional stress imparted thereto and, accordingly, is relatively free of curl or distorsion, providing improved straightness capability as well as minimizing the possibility of the cord end becoming loose and untwisted.

It should also be noted that the arrangement of the over twister 4 in series with the double twister 1 facilitates a more simplified and accurate control of the amount of permanent torsional stress present in the final wire elements than if a large maount of twist corresponding to the total twist by the double twister l and the over twister 4 is achieved by a single twister unit. Since exceptionally high speed rotation is not required, the equipment can be greatly simplified and exhibit a long extended usage.

Further, the twisting machine of the invention will be readily adapted for combining the wire twisting process with the subsequent over twisting and wrapping steps to provide a tandem manufacturing system.

What is claimed is:

l. A wire twisting machine comprising a double twister having at least one supply reel in a floating cradle for imparting twist to a plurality of individual wire elements drawn from said supply reel, a stationary take-up means, and an over twister provided between said double twister and said take-up means, said over twister including roller elements adapted to turn about the path of travel of a twisted wire cord in a direction counter to the rotation of said double twister and at a speed of revolution sufficient to convert at least part of the elastic strain which has been imparted to the individual wire elements by said .double twister to a corresponding permanent strain.

2. A wire twisting machine defined in claim 1 wherein said over twister includes two spaced rollers adapted to turn about the effective path of travel of the wire cord, said rollers being arranged so that a portion of the wire cord extends around said two spaced rollers in a figure eight.

3. A wire twisting machine defined in claim 1 which further includes a wire tension adjusting device comprising a braking wheel rigidly mounted on each supply reel, a tension belt secured to said cradle at one end and extending around said braking wheel, an arm pivoted at one end to said cradle and slidably engaging the outermost layer of a wire winding on the supply reel by means of the other end thereof, and linkage means secured to the other end of said belt and said arm to vary the force applied to said tension belt on said braking wheel in dependence upon the angular displacement of said arm with a decrease in the diameter of the winding on the supply reel.

4. A wire twisting machine defined in claim 1 which further includes capstan means, break detector means said floating cradle, imparting over twist to the twisted wire cord by roller means turning about the path of travel of the wire cord in a direction counter to that of said double twisting and at a speed of revolution sufficient to convert at least part of the elastic strain which has been imparted to said individual wire elements in the previous double twisting step to a corresponding permanent strain, and taking up the twisted wire cord.

Claims

1. A wire twisting machine comprising a double twister having at least one supply reel in a floating cradle for imparting twist to a plurality of individual wire elements drawn from said supply reel, a stationary take-up means, and an over twister provided between said double twister and said take-up means, said over twister including roller elements adapted to turn about the path of travel of a twisted wire cord in a direction counter to the rotation of said double twister and at a speed of revolution sufficient to convert at least part of the elastic strain which has been imparted to the individual wire elements by said double twister to a corresponding permanent strain.

4. A wire twisting machine defined in claim 1 which further includes capstan means, break detector means disposed to extend across a plurality of parallel loops of a twisted wire cord running over said capstan means, said break detector means comprising a U-shaped insulating member including an open end and having the inner surface thereof covered by an electrically conductive plate.

5. A process of producing wire cord, comprising the steps of imparting double twist to a plurality of individual wire elements drawn from at least one supply reel within a floating cradle and forming a balloon around said floating cradle, imparting over twist to the twisted wire cord by roller means turning about the path of travel of the wire cord in a direction counter to that of said double twisting and at a speed of revolution sufficient to convert at least part of the elastic strain which has been imparted to said individual wire elements in the previous double twisting step to a corresponding permanent strain, and taking up the twisted wire cord.