MXPA96005124A - Ac cable - Google Patents

Abstract

The present invention relates to a steel cable characterized in that it comprises at least eight strands twisted together, all the strands of the steel cable having the same torsion direction called cable torsion direction and a substantially equal torsion pitch called the cable pitch. Twist of cable, each of the strands consisting of two to five individual strands twisted together

Description

STEEL CABLE The present invention relates to a steel cable comprising a number of strands twisted together, which is called multiple strand steel cable. One or two decades ago, multiple strand steel cables were steel cables to reinforce elastomeric products such as rubber tires, conveyor belts, transmission belts. A general trend towards simpler constructions comprises fewer filaments with diameters with larger filament diameters, however, it has replaced multiple strand steel cables except for those areas where multiple strand steel cables except for those areas where Multiple strand steel cables were actually needed because of their relatively thin filaments and the resulting high level of fatigue resistance or because of their high load to rupture. Today, multiple-strand steel cables are still common for reinforcing thick tires such as off-road tires, conveyor belts, timing bands and transmission belts.

Multiple strand steel cables are manufactured in an expensive way, the last steps can be summarized as follows: (a) untangle filaments, wet-extract the filaments until their final filament diameter and wind the filaments thus extracted; (b) untangle the extracted filaments, twist the filaments to individual strands and wind the twisted strands; (c) untangle the strands, twist the strands to a final cable and wind the twisted cable. Especially step (b), which must be performed for each individual strand of the final cable, for example, seven times in the case of a 7X19 cable, is disadvantageous to the productivity and efficiency of the process for making multiple strand steel cables. . It is an object of the present invention to provide a new scale of steel cables of multiple strands, which allow to omit the separate steps (b) of making the individual strands and to replace the commonly used multiple strand steel cables such as cables. of 7 X 7, 7 X 19 cables, 7 X 31 cables. According to the invention, a steel cable is provided, which comprises eight or more strands twisted together. Each of the strands has a substantially equal cable twist direction and a substantially equal cable twist pitch. Each of the strands consists of two to five individual strands twisted together. The terms "cable twist pitch" refers to the axial distance required to make a 360-degree revolution of a strand in the final cable. As will be explained later, the fact that the strands have the same direction of twisting of the cable and of the same twisting pitch, allows the multi-strand steel cable to be made in an economical and highly efficient way. The fact that each of the strands consists of only two to five individual filaments and, as a consequence, does not comprise any core filament allows the multiple strand steel cable to be experienced without experiencing migration problems of core filament in the individual strands. . In a preferred embodiment of the invention, the individual steel filaments of each strand have the same direction of strand twisting and the thread twisting step substantially equal. The terms "thread twist pitch" refers to the axial distance required to make a 360-degree revolution of a filament in a strand of the final wire.

The number of strands in the multi-strand steel cable according to the invention is at least eight, and may be nine, twelve, fifteen, in order to provide a suitable alternative for prior art cable constructions. 7 X 7, 7 X 19, 3 X 31. However, the preferable configurations comprise 12, 19 or 27 strands and are respectively designated as 12xn-, 19xn- and 27xn, where n is the number of filaments in each strand and varies from two to five. A 12xn cable has three central strands and nine external strands. A 19xn cable has a central strand, six intermediate strands and twelve outer strands. A 27xn cable has three central threads, nine intermediate threads and fifteen external threads. In order to prevent the central strand or central strands from migrating out of the cable under the influence of repeated external bending force, it is preferred that the central strand or core strands have a diameter greater than the diameter of the outer strands and / or strands intermediate The twisting direction of the strand may be equal to or opposite to the twisting direction of the strand. As will be apparent below, a multi-strand steel cable, wherein the strand twist direction is equal to the twist direction of the cable, can be made in a highly efficient manner. The strand twist pitch may be equal to or different from the cable twist pitch. The multi-strand steel cable is preferably adapted to reinforce elastomeric products, which means that it has either alone or in combination, one or more of the following properties: - the filament diameters vary from 0.4 mm (for example, to reinforce a time control band) to 1.1 mm (for example to conveyor belts); - the steel composition generally comprises a minimum carbon content of 0.60%, a manganese content ranging from 0.20 to 0.90% and a silicon content ranging from 0.10 to 0.90%; the sulfur and phosphorus contents are preferably kept below 0.03%; additional elements such as chromium, gold, cobalt, nickel, etc. may be added to the composition; the filaments are conveniently covered with a corrosion resistant coating such as zinc or with a coating that promotes adhesion to the elastomeric material such as brass or bronze. Other applications of the multiple strand cable outside the field of the elastomeric reinforcement are not excluded. In this form, the multiple strand cable according to the invention can be covered with a synthetic material such as polyamides.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to the accompanying drawings in which: FIGURES 1, 2 and 3 show cross sections of 12xn cables according to the present invention; - FIGURE 4 shows a cross section of a 19xn cable according to the present invention; - FIGURE 5 shows a cross section of a 27xn cable according to the present invention; and FIGURE 6 shows schematically how a multi-strand cable can be made according to the invention. FIGURE 1 shows a cross-section of a 10-strand steel cable-multiple of 12 X 2. The cable 10 comprises three central strands 12 and nine outer strands 14. Each of the central strands 12 and each of the outer strands 14 consist of only two filaments 16. Each of the central strands 12 and the outer strands 14 have the same cable twisting step and the same twisting direction of the cable in the final cable 10, for example: 12 X 2 X 0.20 in cable twist pitch = 10 mm wire twist direction = Z thread twist pitch = 10 mm thread twist direction = S 12 X 2 X 0.20 wire twist pitch = 20 mm wire twist direction = S strand twist pitch = 10 mm strand twist direction = S. FIGURE 2 shows a cross section of a 12 x 3 multi strand steel wire. Steel wire 10 comprises three core strands 12 and nine external strands 14. The diameter of l The middle strands 12 is a little larger than the diameter of the outer strands 14, since the strands 18 of the middle strands have a filament diameter that is greater than the strands 16 of the outer strands. An example is as follows: 3 x 3 x 0.175 | 9 x3 x 0.15 wire twist pitch and direction = 8Z pitch and twist torsion direction = 8S. FIGURE 3 shows a cross section of another mode cord, which also comprises three central strands 12 and nine outer strands 14. The central strands 18 have a diameter greater than the diameter of the external strands 18 by the fact that they consist of three filaments 18, while the outer strands 14 only consist of two filaments 16. The filaments 18 of the central strands and the filaments 16 of the outer strands have an equal diameter. An example is: 3 x 3 x 0.15 | 9 x 2 x 0.15 pitch and direction of cable twist = 16S pitch and strand direction = 8S. FIGURE 4 shows a cross section of a multiple 10-strand steel wire of 19 x 4. The wire comprises a central strand 12, six intermediate strands 20 and twelve outer strands 14. Each strand consists of four strands. The four strands of the central strand 12, however, have a diameter that is slightly larger than the diameter of the filaments of the intermediate strands 20 and the outer strands 14. FIGURE 5 shows a cross section of a steel cable 10 of multiple strands of 27x2 . The cable comprises three central strands 12, nine intermediate strands and fifteen external strands 14. Each strand consists of two strands. The two filaments 18 of the central strand 12, however, have a diameter that is a little larger than the diameter of the filaments 16 of the intermediate strands 20 and the outer strands 14. The steel strands of multiple strands according to the The invention can be used to replace common multiple strand steel cables without loss of breaking load or other mechanical properties. Some examples: - a cable of 7 x 7 xd has 49 filaments and can be replaced by a cable of 19 x 2 x x- ^ (38 filaments) with dL greater than do by one of l9 x 3 x d2 (57 filaments) with a d2 smaller than d; - a 19 x 7 x d cable has 133 filaments and can be replaced by a 27 x 5 x d (135) filament cable). FIGURE 6 illustrates how a 12 x 3 multi-strand steel cable, according to the invention, it can be done in a single step to make the cable, thus avoiding the multiple steps to make the individual strands. Starting from the. left side of FIGURE 5, three individual filaments 16 are ejected on a supply spool or reel 22 or three separate supply spools 22. The filaments 16 are guided via a reversal pulley 23, on a fin 24 toward a pulley guide 25. The fin 24 rotates at a rotational speed and provides the filaments 16 with two rotational torsions so that a strand 14 (provisional) is made. This is done twelve times simultaneously. The entire set of 12 supply coils 22 and the corresponding fins 24 form a so-called decisive rotation installation. The twelve provisional strands are placed together at a point of 16 and are guided to a false twister 28, which rotates at twice the rotational speed nß of a downstream double torcerator. The function of this false twist 28 is to extract exact stretches of the strands that as mentioned in the final cable, since at the level of the false twist 28 the cable temporarily reaches its final cable twist pitch. After leaving the false twist 28, the assembled strands are driven via a guide pulley 30, on a fin 32 and a reversing pulley 34 and finally are wound on a spool 36. The fin 32 rotates at a rotational speed nß, two rotations to the assembled strands and reaches the final wire twisting step of the multi-strand cable 10 and also (together with the rotation vanes 24) to the final step of the strand twist pitch. Let's suppose a first example as the following situation: - fin 32 of the double torcer rotates at a rotational speed nß of 2000 pro in the direction of arrow 38 as indicated in FIGURE 6 (Z are given to torsion); the fins 24 of the decisive rotation installation rotate at a rotational speed j ^^ of 4000 pro (= 2xnp) in the direction of the arrow 40 (give S to the torsion).

This results in a 12x3 multiple strand cable with the following characteristics: - - cable twist pitch and direction = X mm S - cable twist pitch and direction = X mm Z, since half of the torques given the strands by means of the fins 24 have been compensated by means of the fin 32 running low in the final step of cable manufacture; - suppose a second example in the following situation: - the fin 32 of the double torcerator rotates at a rotational speed nß of 1000 pro in the opposite direction of the arrow 38 as indicated in Figure 6 (S is given to the torsion); the fins 24 of the decisive rotation installation rotate at a rotational speed in n ^^ -, of 1000 pro (= 2 x nB) in the direction of arrow 40 (also give S to the torsion). This results in a 12 x 3 multi-stranded cable with the following characteristics: - cable twist pitch and direction: 2X mm S, since the fin 32 rotates at half the speed of the fin 32 in the first example; - pitch and direction of twist of the strand = X mm £, since the torsions given by the fins 24 of the decisive rotation installation and the torsions given by the fin 32 in the double torcerator are now added. This second example illustrates an advantageous embodiment of the multiple strand cable according to the invention. If the direction of torsion of the cable and the direction of twist of the thread are equal, these torsions given by the fins of the decisive installation of rotation are added to the torsions given by the fin of the double torcedor, so that the final torsions are obtained with a minimum of torque energy (compared to much higher speed rotations of the first example with the rotational speeds of the second example). The rotational speed nj ^ Q of the fins of the decisive installation of rotation is in any form different from the rotational speed nß of the fin of the double torcedor in order to avoid a situation where the torsions given by the fins of the decisive installation The rotation could be one hundred percent compensated by the torsions given by the double twist fin, which would result in steel cables where the difference between the strands could disappear and result in the so-called compact steel cables consisting only of of filaments, having the same pitch of cable twist and cable twist direction, which are equal to the strand twist pitch and the strand twist direction.

Claims (5)

1. CLAIMS 1. A steel cable characterized in that it comprises eight or more strands twisted together, each of the strands having a substantially equal cable twist direction and a cable twisting step substantially equal in the steel cable, each of the strands consisting of two to five individual strands 16, 18, twisted together.
2. 2. A steel cable according to claim 1, characterized in that the individual filaments of each of the strands has been twisted in the same twisting direction of the strand and with the same twisting step of the strand.
3. 3. A steel cable according to claim 1 or 2, characterized in that the number of strands in the steel cable is twelve: three central strands and nine outer strands. A steel cable according to claim 3, characterized in that all the outer strands have a substantially equal external thread diameter and at least one of the middle strands has a thread diameter greater than the strand diameter of the strands external. 5. A steel cable according to claim 4, characterized in that all the outer strands have filaments with a substantially equal filament diameter, a central strand comprising filaments having a diameter that is greater than the filament diameter of the filaments of the outer threads. 6. A steel cable according to claim 4 or 5, characterized in that all the external strands have the same number of filaments, at least one central strand comprising more filaments than the outer strands. 7. A steel cable according to claim 1 or 2, characterized in that the number of strands in the steel cable is 19, a central strand, six intermediate strands and twelve outer strands. 5. A steel cable according to claim 8, characterized in that the intermediate strands have a substantially equal diameter and all the outer strands have a substantially equal diameter, the central strand having a diameter that is greater than the diameter of the strands external and greater than the diameter of the strands . A steel cable according to claim 1 or 2, characterized in that the number of strands in the steel cable is twenty-seven, three central strands, nine intermediate strands and fifteen outer strands. 10. A steel cable according to claim 9, characterized in that all the intermediate strands have a substantially equal diameter and all the outer strands have a substantially equal diameter, at least one of the central strands having a diameter that is greater than the diameter of the intermediate threads and greater than the diameter of the external threads. 11. A steel cable according to any of claims 2 to 10, characterized in that the twisting direction of the cable is equal to the direction of torsion of the strand. 12. A steel cable according to any of claims 2 to 10, characterized in that the twisting direction of the cable is opposite to the twisting direction of the strand. 13. A steel cable according to any of claims 2 to 12, characterized in that the cable short twisting step is substantially equal to the twisting pitch of the strand. 14. A steel cable according to any of claims 2 to 12, characterized in that the twisting step of the cable is different from the twisting pitch of the strand. 15. A steel cable according to claim 1, characterized in that the individual filaments of some of the strands have been twisted in a strand twist direction or with a strand twist pitch different from the strand twist direction or of the strand twist pitch of the other strands.