Method and device for stranding single cable

Abstract

To provide a method and a device for stranding a pair of single cables about a twist axis to form a cable bundle.SOLUTION: In a twisting device 400, single cables are arrayed along each cable axis V1, V2, and have wires which are stranded in a twist direction P of a strand to form a strand, first cable ends 15, 16, and second cable ends. The first cable ends are individually held by single rotation units 41, 42. The second cable ends are held by a twist unit 30. The second cable ends are rotated together in the opposite direction to the twist direction of the strand about a twist axis V to generate a twisted cable bundle 10. While being rotated together, the first cable end is individually rotated in the same direction as a direction of being rotated together about each cable axis of the single cables. This alleviates a torsion of the single cable.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to methods and apparatus for twisting single cables, and more particularly to methods and apparatus for twisting pairs of single cables to form a cable bundle. [Background technology]

[0002] Cable bundles obtained by twisting together several individual cables (hereafter referred to as twisted cable bundles) are required in various industrial fields. Each individual cable has a strand, which is made up of twisted wires (hereafter referred to as twisted strands). An insulation surrounds each strand of the individual cables. Before twisting the cable bundles, the individual cables are usually cut to a predetermined length, i.e. trimmed, and assembled if necessary, i.e. provided with contact elements, etc.

[0003] EP 1 032 095 discloses a twisting device for simultaneously processing three conductor pairs. The conductor pairs, i.e. the pairs of a single cable, are clamped between a holding unit and a twisting head. The twisting process is carried out by rotating the twisting head about a twisting axis. The resulting shortening of the conductor pairs is compensated for by moving the twisting head parallel to the twisting axis. The twisting device disclosed in EP 1 032 095 serves not only the purpose of assembling cables, but also the purpose of twisting cables (hereinafter referred to as automatic production). In a known variant, the twisting device is only used for twisting and not for assembling cables (hereinafter referred to as semi-automatic production). In the case of the device according to the variant, the compensation of the shortening associated with the twisting of the conductor pairs is carried out, for example, by moving the holding unit parallel to the twisting axis.

[0004] WO 2013 / 068990 discloses a twisting device similar to the one disclosed in EP 1 032 095, whereby two twisting heads are provided which rotate in opposite directions.

[0005] WO 98 / 06155 discloses a twisting device similar to that disclosed in EP 1 032 095. In this device, instead of a holding unit, there is a respective untwist unit at each cable end which rotates in the same rotational sense as the twist head during the twisting process. Issues to be resolved The specified properties that the resulting cable bundle should have upon twisting of the cable bundle include, for example, the desired lay length or twisted lay length, as well as the desired number of lays or number of twisted lays. Generally, the lay length is understood to be the distance or average distance between two adjacent crossing points of a single cable when projected onto a plane. The lay number is the sum of these crossing points.

[0006] The cable bundle obtained by twisting the cable bundle always has a certain elasticity around the twist axis. In the case of cable bundles obtained by twisting the cable bundle according to EP 1 032 095 and WO 2013 / 068990, the cable bundle (here the cable pairs) tends to untwist in the opposite direction to the twisted state after the end of the twisting process, resulting in at least partial untwisting. The number of lays and / or the lay length may therefore change to an unacceptable state or deviate from the specified values. It is known to counteract this phenomenon by continuing the twisting process longer than necessary for the desired lay length and / or number of lays ("over-twist"). It is also possible to carry out a rotational movement in the opposite direction ("reverse twist"), which prevents or reduces, respectively, the elastic deformation of the cable bundle. Over-twisting may result in large undesirable or unacceptable torsional forces, respectively, especially for cables with small strand cross-sections.

[0007] In WO 98 / 06155 an attempt is made to avoid excessively high twisting forces in that the untwisting unit performs twist compensation during the twisting process. Due to the fact that the cable ends are not clamped in the untwisting unit with rotation fixed relative to the twisting head, a guide unit in the form of a drill shuttle is provided to determine the lay length. The guide unit separates the two cables by means of a pin and moves from the twisting head towards the untwisting unit during the twisting process.

[0008] However, in the case of cable bundles obtained with WO 98 / 06155, the lay lengths are scattered in an unacceptable manner, i.e. the deviations in lay lengths between two similar cable bundles, but also within the same cable bundle, can be unacceptably large. In the case of cable bundles obtained with the technique according to WO 98 / 06155, in some cases too large distances between crossing points are formed between single cables (so-called large eyes), which reduces the quality of the obtained cable bundle.

[0009] Considering the above problems, the present objective is to demonstrate an improved option for twisting single cables to form a cable bundle. Summary of the Invention

[0010] According to one aspect, a method is provided for twisting single cables about a twist axis. The single cables are aligned along their respective cable axes. Each single cable has a plurality of wires that are twisted together to form a strand, i.e., twisted in the twist direction of the strand. Each single cable further has a first cable end and a second cable end. The method includes holding the first cable end separately and holding the second cable end to rotate them together about the twist axis in a direction opposite to the twist direction of the strands to create a twisted cable bundle with a defined or definable number of lays and / or a defined or definable twisted lay length. During the rotating together, the first cable ends are rotated about the cable axis of each single cable, i.e., in the same direction as the rotating together, to relieve tension in each single cable.

[0011] According to a further aspect, there is provided an apparatus configured to carry out the methods described herein. The apparatus has a single or separate rotating unit and twisting unit. The single rotating unit is configured to individually hold a respective one of the first cable ends. The twisting unit is configured to hold the second cable ends. The single rotating unit and twisting unit are arranged to hold the single cable essentially parallel to the twist axis.

[0012] Further aspects, features, advantages and benefits can be found in the embodiments described below with reference to the drawings. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of areas of a cable bundle to explain the terminology used in this application. [Diagram 2] FIG. 2 is a schematic diagram of a twisting device having a twisting unit and a holding unit. [Diagram 3]FIG. 3 shows a schematic diagram of a twisting device having two twisting units arranged opposite each other. [Figure 4] FIG. 4 shows a schematic diagram of a twisting device having a twisting unit as well as a single rotating unit for each single cable. [Diagram 5] FIG. 5 is a schematic diagram of a cable bundle including a single cable to illustrate the twist direction of the wires and the twist direction of the cables. [Figure 6] FIG. 6 shows the area of ​​production of cable bundles for the "Lang-lay twist" alternative. [Figure 7] FIG. 7 shows the area of ​​cable bundle manufacture for the alternative "counter-lay twist." DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 1 is a schematic diagram of a region of a cable bundle generally designated by the reference numeral 10. The cable bundle includes a cable pair, a single cable 11 and a single cable 12. It should be noted that the number of two single cables 11, 12 is exemplary and non-limiting, and the aspects and features described herein may be fully or partially applied to a cable bundle having three or more single cables 11, 12 with the same or similar effect. Nonetheless, in this embodiment, two single cables 11, 12 may be used in one cable bundle 10.

[0015] In FIG. 1, the first cable end 15 of the single cable 11 and the first cable end 16 of the single cable 12 are located on the same side. As an example, the first cable ends 15, 16 are already processed in the form that the contacts 13a and the grommet 13b are attached to the first cable end 15, and the contacts 14a and the grommet 14b are attached to the second cable end 16. The single cables 11, 12 each have a strand, which is formed of twisted wires, as will be explained in more detail below with reference to FIG. 5. In the area to the right of the dashed line indicated by B in FIG. 1, the single cables 11, 12 are twisted together, as a result of which there are multiple points at which the single cables 11, 12 cross in the projection plane, for example the plane of FIG. 1. If there is the same arrangement of the single cables at two crossing points in the direction perpendicular to the projection plane, there will be similar crossing points in the projection plane. The distance between two adjacent similar crossing points is called the twisted lay length or simply the lay length for short, and is indicated by a. Two eyes 19, which should be as small as possible for a high-quality cable bundle 10, arise between two adjacent similar intersection points in the projection plane.

[0016] The terms from FIG. 1 are used in the following paragraphs and will not be explained again.

[0017] Fig. 2 shows a schematic diagram of a general twisting device 200 comprising a cable bundle 10 in which two single cables 11, 12 are clamped. The second cable end 17 of the single cable 11 is located opposite the first cable end 15 of the single cable 11. The second cable end 18 of the single cable 12 is located opposite the first cable end 16 of the single cable 12. The second cable ends 17 and 18 are clamped together in a twisting unit 30. The first cable end 15 is clamped in a first holding unit 21. The first cable end 16 is clamped in a second holding unit 22. The twisting unit 30 is configured to be rotatable about a twisting axis V for performing a twisting process in a twisting direction P. To compensate for shortening of the single cables 11, 12 that are twisted together during the twisting process, the twisting unit 30 can be moved in a direction u that is essentially parallel to the twisting axis V. In this application, a direction parallel to the twist axis V includes the direction of the twist axis V itself.

[0018] Figure 3 shows a twisting device 300 according to the twisting device 200 of figure 2. In contrast to the twisting device 200, in the twisting device 300 the holding units 21, 22 are not present. Instead, a further twisting unit 31 is provided. The front ends 15, 16 are clamped together in the further twisting unit 31. The twisting unit 30 is configured so that it can rotate about a twisting axis V while performing a twisting process in a twisting direction P, whereas the further twisting unit 31 is configured so that it can rotate about a twisting axis V while performing a twisting process in the opposite direction Q.

[0019] In the twisting devices 200, 300 shown in Figures 2 and 3, if a sufficient mechanical pretension is applied to the single cables 11, 12, an essentially uniform lay length a is obtained over a sufficiently large area of ​​the cable bundle. The lay length depends strongly on the material properties of the single cables 11, 12 and on the number of turns of the twisting unit 30 or of the separate twisting unit 31 during the twisting process. Especially in the case of smaller strand cross-sections, twisting of the single cables 11, 12, i.e. high mechanical pretension of the single cables, is undesirable.

[0020] Figure 4 shows a twisting device 400 similar to Figures 2 and 3, which can be used to carry out the method disclosed herein, according to one embodiment. The twisting device 400 differs from the twisting device 300 of Figure 3, in that a single rotating unit (separate rotating unit) 41 is provided for clamping the first cable end 15 of the single cable 11, and a single rotating unit 42 is provided for clamping the first cable end 16 of the single cable 12. The single rotating unit 41 is arranged to hold the first cable end 15 of the clamped single cable 11 at the first cable end 15 along its cable axis v1. The single rotating unit 42 is arranged to hold the first cable end 16 of the clamped single cable 12 at the first cable end 16 along its cable axis v2. Both single rotating units 41, 42 are essentially arranged to hold the single cables 11, 12 at their respective first cable ends 15, 16 parallel to the twist axis V.

[0021] In figure 4 the twisting device 400 further comprises guide means 35 for at least partially separating the single cables 11, 12. The guide means 35 can be moved in an x-direction essentially parallel to the twisting axis V. By a guided or controlled movement of the guide means 35 during the twisting process the lay length a can be kept constant or can be varied as required.

[0022] 2 and 3, the twisting units 30 in the twisting device 400 of FIG. 4 can be driven in rotation about a twisting axis V, at least in the twisting direction P. The single rotating unit 41 can optionally rotate in the forward and backward directions about the cable axis v1. This is suggested by the double arrow Q1 in FIG. 4. The single rotating unit 42 can optionally rotate in the forward and backward directions about the cable axis v2. This is suggested by the double arrow Q2 in FIG. 4.

[0023] The method disclosed herein provides that the first cable ends 15, 16 are held separately, for example by a single rotating unit 41, 42 of the device 400 of Fig. 4. This holding characterizes the state before the start of the twisting process, for example when the single cables 11, 12 are clamped in the device 400, i.e. the twisting process takes place after this holding.

[0024] During the twisting process, the second cable ends 17, 18 rotate together about the twist axis V, resulting in the formation of a twisted cable bundle 10 comprising a defined or definable number of twisted trays and / or comprising a defined or definable twisted tray length a.

[0025] In contrast to methods known from the prior art, this co-rotation about twist axis V is performed in the opposite direction to the twist direction of the strands, as will be further explained below with reference to FIG.

[0026] In contrast to the methods known from the prior art, each of the first cable ends 15, 16 is rotated individually around its respective cable axis v1, v2 during this co-rotation, i.e. in the same direction as this co-rotation, for example by driving the corresponding single rotating unit 41, 42 in a direction that coincides with the rotation direction Q1 or Q2, respectively, thereby untwisting each single cable 11, 12.

[0027] As used herein, detwisting includes, for example, reducing or eliminating the torsional forces or moments generated by the rotation of each single cable 11, 12 together. Detwisting or detwisting does not necessarily have to be complete to achieve the advantages described herein. This means that over the course of the twisting process, the (total) rotation angle of the twisting unit 30 can be smaller than the (total) rotation angle of the single rotating units 41, 42.

[0028] In the methods described herein, the twisting is performed in counter-twist, whereby counter-twist means an opposite rotation between the twist direction of the (rotating) cable and the twist direction of the (rotating) strands.

[0029] FIG. 5, for example, shows diagrammatically a cable bundle 10 of two single cables 11, 12 and the strands in two alternatives. In alternative A (left side of FIG. 5), the twist direction of the strands is clockwise (strand twist direction S) as seen from the cable end. The twisted wires 11a, 12a forming the strands of alternative A therefore run from the upper left to the lower right in the illustrated projection. The single cables 11, 12 forming the twisted cable bundle 10 of alternative A therefore run from the lower left to the upper right in the illustrated projection (cable twist direction Z). In the alternative (right side of FIG. 5), the twist direction of the strands is counterclockwise (strand twist direction Z) as seen from the cable end. The twisted wires 11a, 12a forming the strands of alternative B therefore run from the lower left to the upper right in the illustrated projection. Therefore, the single cables 11, 12 forming the twisted cable bundle 10 of alternative B run from the upper left to the lower right (cable twist direction S) in the illustrated projection plane.

[0030] It has been shown that twisted cable bundles 10 with very small lay length and lay number variations or deviations, respectively, and very small eyes, can be obtained by the method described herein. At the same time, each single cable 11, 12 is only slightly twisted by the approach described herein. The resulting cable bundle 10 has no or only minimal tendency to untwist.

[0031] FIG. 6 shows a qualitative plot of the twisted lay length a (cable lay length) compared to the strand lay length b, i.e., twist in Lang lay (equal lay) according to the prior art. FIG. 7 shows a qualitative plot of the twisted lay length a (cable stroke length) compared to the strand lay length b, i.e., twist in opposite direction lay (reverse lay) as in the method described herein. The regions in which the cable bundle shows good quality characteristics are in each case designated with the reference 50. The regions in which the cable bundle no longer shows optimal quality characteristics are in each case designated with the reference 60. The regions in which the cable bundle can no longer be manufactured are respectively designated with the reference 70. It has been shown that the approach in opposite direction lay according to the method described herein results in significant process improvements.

[0032] Further alternatives and embodiments are described below in conjunction with the figures described in more detail above.

[0033] According to one embodiment, the method further comprises rotating each of the first cable ends 15, 16 individually about the cable axis v1, v2 for pre-twisting of each single cable before rotating together. Pre-twisting as used herein comprises applying a twist to each of the single cables in a regular manner before the twisting step. The pre-twisting is performed such that damage related to twisting to each of the single cables is avoided. The pre-twisting has an effect comparable to the over-twisting and subsequent reverse twisting described above with reference to the prior art, except that it has been shown that the strands are less distorted. It has further been shown that in the method extended by pre-twisting, the single cables 11, 12 abut each other more closely in the pre-twisted cable bundle 10, reducing the eye size without increasing the pre-tension. The twisted cable bundle 10 also remains more dimensionally stable. The tendency of the untwisted cable ends 15, 16, 17, 18 to automatically untwist is further reduced.

[0034] In one alternative, separate rotations for pre-twisting are performed in each case in the twist direction S, Z of the strands. With this alternative, it is possible to compensate for the shape of the helix of the twisted cable bundle 10 in each single cable x, whereby the twisting of the twisted cable bundle 10 is reduced or even completely eliminated.

[0035] In another alternative, the individual rotations for pretwisting are in each case performed in the opposite direction to the twist direction S, Z of the strands. This alternative further reduces the formation of large eyes. Moreover, this alternative further reduces the tendency of the untwisted cable ends 15, 16, 17, 18 to automatically untwist.

[0036] According to one embodiment, the individual rotations for pre-twisting of each of the first cable ends 15, 16 are performed with a rotation angle of up to 10% of the total rotation angle of the second cable ends 17, 18 required to reach the twisted lay number. It has been shown that such a pre-twist of up to 10% of the lay number is sufficient to achieve the effects and advantages described herein.

[0037] According to one embodiment, the method further comprises iteratively determining a variable related to a torsional moment or force of at least one of the single cables, wherein individual rotations of the first cable end about the cable axis of each single cable are performed until the determined variable falls below a predetermined or predeterminable threshold.

[0038] According to one embodiment, the method further comprises trimming the single cable. Alternatively or additionally, the method further comprises attaching one or several contact pieces 13a, 13b, 14a, 14b to at least one of the first cable ends 15, 16 and the second cable ends 17, 18.

[0039] According to an embodiment, the method further comprises moving the first and second cable ends towards each other, thereby compensating for twist-related shortening of the cable bundle. For example, for this purpose the twisting unit 30 is movably arranged parallel to the twisting axis V. Alternatively or additionally, every single rotating unit 41, 42 is movably arranged parallel to the twisting axis V for this purpose. For this purpose the device 400 is configured to move the first and second cable ends 11, 12 towards each other, for example by the movably arranged twisting unit 30 and / or the single rotating unit 41, 42, in order to compensate for twist-related shortening of the cable bundle.

[0040] According to one embodiment of the device 400, the twisting unit 30 is arranged to be movable parallel to the twisting axis V. Alternatively or additionally, every single rotating unit 41, 42 is arranged to be movable parallel to the twisting axis V. The device 400 is configured to apply a tension essentially parallel to the twisting axis V in order to stretch the single cables 11, 12 and / or the cable bundle 10. The stretching can be performed before and / or during twisting. This allows to further improve the uniformity of the twisted cable bundle 10, in particular the lay length a.

[0041] According to one embodiment of the device 400, the latter comprises guide means 35 for at least partially separating the single cables 11, 12. The guide means 35 are movable in a direction x essentially parallel to the twist axis V. The device 400 is configured such that the guide means 35 moves in the direction x of the first cable ends 15, 16 essentially synchronously with a variable related to the rotation of the twisting unit 30. This allows to further improve the uniformity of the twisted cable bundle 10, in particular the lay length a.

[0042] It should be noted that the aspects, features and embodiments described herein can be combined as desired in the context of the actions of those skilled in the art, and / or individual features can be modified or omitted. The described embodiments are exemplary, and features thereof can be modified or adapted, and combined and / or omitted as appropriate, without departing from the scope of the present disclosure as defined in the claims.

Claims

1. A method for twisting single cables (11, 12) about a twist axis (V), comprising the steps of: The single cables (11, 12) have wires (11a, 12a) aligned along respective cable axes (v1, v2) and twisted together in strand twist directions (S, Z) to form the strands, and a first cable end (15, 16) and a second cable end (17, 18); holding the first cable ends (15, 16) separately and holding the second cable ends (17, 18); rotating the second cable ends (17, 18) together about the twist axis (V) in a direction opposite to the twist direction (S, Z) of the strands to create a twisted cable bundle (10) having a defined or definable number of lays and / or a defined or definable lay length; prior to said co-rotating, rotating said first cable ends (15, 16) separately about said cable axis (v1, v2) of said single cable for pre-twisting; rotating the first cable ends (15, 16) individually about the cable axis (v1, v2) of each of the single cables (11, 12) in the same direction as the co-rotation to relieve tension in each of the single cables during the co-rotation.

2. The method of claim 1 , wherein the individual rotating for pre-twisting is performed in a twist direction (S, Z) of the strands.

3. 2. The method of claim 1, wherein the individual rotating for pre-twisting is performed in a direction opposite to the twist direction (S, Z) of the strands.

4. 4. The method according to claim 1, wherein the individual rotation of the first cable ends (15, 16) for the pre-twisting is performed with a rotation angle of at most 10% of the total rotation angle of the second cable ends (17, 18), which is the rotation angle required to reach a twist tray number.

5. Iteratively determining a variable related to a torsional moment or a torsional force of at least one of the single cables (11, 12), 5. The method according to any one of claims 1 to 4, wherein individual rotations of the first cable ends (15, 16) about the cable axes (v1, v2) of each of the single cables (11, 12) are performed until the determined variable falls below a predetermined or predeterminable threshold value.

6. 6. The method according to any one of claims 1 to 5, wherein the twisted cable bundle (10) comprises two of the single cables (11, 12).

7. Trimming the single cable; and / or 7. The method according to claim 1, further comprising attaching one or more contact elements (13a, 13b; 14a, 14b) to at least one of the first cable end (15, 16) and the second cable end (17, 18) of the single cable (11, 12).

8. 8. The method according to any one of claims 1 to 7, further comprising applying tension along the twist axis (V) to elongate the single cables (11, 12) and / or the twisted cable bundle (10) prior to said co-rotating.

9. 9. The method according to any one of claims 1 to 8, further comprising moving the first and second cable ends (15, 16; 17, 18) towards each other to compensate for shortening associated with twisting of the twisted cable bundle (10).

10. A device (400) for twisting single cables (11, 12) about a twist axis (V), comprising: The single cables (11, 12) have wires (11a, 12a) aligned along respective cable axes (v1, v2) and twisted together in strand twist directions (S, Z) to form the strands, and a first cable end (15, 16) and a second cable end (17, 18); a single rotating unit (41, 42) for individually holding each of the first cable ends (15, 16); a twisting unit (30) for holding the second cable ends (17, 18); the single rotating unit (41, 42) and the twisting unit (30) are arranged to hold the single cable (11, 12) parallel to the twist axis (V); The apparatus (400) is configured to perform the method according to any one of claims 1 to 9.

11. 11. Apparatus (400) according to claim 10, wherein said twisting unit (30) is drivable in rotation about said twisting axis (V).

12. 12. The device (400) according to claim 10 or 11, wherein either the twisting unit (30) or all of the single rotating units (41, 42), or both the twisting unit (30) and all of the single rotating units (41) are arranged to be movable parallel to the twist axis (V), and the device (400) is configured to move the first and second cable ends (15, 16; 17, 18) towards each other to compensate for shortening associated with twisting.

13. 13. The apparatus (400) according to any one of claims 10 to 12, wherein either the twisting unit (30) or all of the single rotating units (41, 42), or both the twisting unit (30) and all of the single rotating units (41) are arranged to be movable along the twist axis (V), and the apparatus is configured to apply tension along the twist axis (V) to stretch the single cables (11, 12) and / or the twisted cable bundle (10) prior to the co-rotation.

14. 14. The apparatus (400) according to any one of claims 10 to 13, further comprising a guide means (35) arranged between the single rotating unit (41, 42) and the twisting unit (30), the guide means (35) being configured to separate the single cables (11, 12) in at least some regions.

15. 15. The apparatus (400) according to claim 14, wherein the guide means (35) is configured to move in a direction (x) in synchronism with a variable related to a rotation of the twist unit (30).

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