Manufacturing method of multi-pair transmission cable

Abstract

The invention provides a manufacturing method of a multi-pair transmission cable. The multi-pair transmission cable prevents or suppresses reduction of transmission characteristics. A method for manufacturing a multi-pair transmission cable according to one embodiment of the present invention comprises: a first twisting step for twisting a pair of electric wires in a first direction to form a twisted pair; and a second twisting step for twisting a plurality of the twisted pairs in a second direction opposite to the first direction to form a cable assembly. In the second twisting step, the plurality of twisted pairs are twisted in the second direction while back-twisting is performed.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a multi-pair transmission cable. Background Art

[0002] There are known multi-pair transmission cables having a plurality of twisted pairs of wires and a sheath covering the twisted pairs of wires (Patent Document 1). Each twisted pair of wires has a pair of twisted wires, and is generally referred to as a "twisted pair cable" or a "two-strand cable". It should be noted that in this specification, the twisted pairs of wires are sometimes collectively referred to as a "cable assembly".

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 11-25765 Summary of the invention

[0006] Problems to be solved by the invention

[0007] When twisting a plurality of twisted pairs to form a cable assembly, sometimes the twisted pairs are twisted and rotated in a rotation direction opposite to the twisting rotation direction while twisting the plurality of twisted pairs, i.e., so-called back-twisting is performed. By twisting the plurality of twisted pairs while back-twisting, deformation (strain) of the individual twisted pairs can be prevented. As a result, the attenuation of the multi-pair transmission cable can be stabilized.

[0008] On the other hand, if the above-mentioned untwisting is performed when forming the cable assembly, the twist of each twisted pair may be loosened. More specifically, the twist pitch of each twisted pair (the twist pitch of a pair of wires) may be extended compared to the original. Furthermore, if the twist pitch of the twisted pair constituting the cable assembly is extended, the transmission characteristics of the multi-pair transmission cable may be reduced. For example, crosstalk may increase.

[0009] The present inventors inspected a plurality of pairs of transmission cables whose transmission characteristics did not meet the standard values, and obtained the results shown in Table 1. In this inspection, the twist untwisting (elongation of the twist pitch) of each twisted pair was inspected for a cable assembly of 4 pairs of LAN (Local Area Network) cables whose transmission characteristics did not meet the standard values ​​of Category 5e (Cat. 5e).

[0010] Specifically, for the four twisted pairs (No. 1 to No. 4) constituting the cable assembly, the twist pitches at three different locations (point a, point b, and point c) were measured, and the average value (mm) was calculated. Furthermore, the ratio of the calculated average value to the design value (mm) (average value / design value) was calculated as the elongation (%).

[0011] It should be noted that the design values ​​of the twist pitches in the twisted pair cables (No. 1 to No. 4) are intentionally shifted to cope with crosstalk.

[0012] [Table 1]

[0013]

[0014] In this inspection, it was confirmed that the twist pitches of all the twisted pair wires were elongated. Furthermore, the average value of the elongation of the twist pitches of the four twisted pair wires exceeded 110%.

[0015] As a result of the above examination, the inventors of the present application have obtained the following insight: in order to prevent or suppress the reduction of the transmission characteristics of the multi-pair transmission cable, it is important to prevent the twist of the twisted pair wires constituting the cable assembly from untwisting. In other words, the inventors have obtained the following insight: it is important to prevent the twist pitch of the twisted pair wires constituting the cable assembly from extending.

[0016] Methods for solving problems

[0017] A method for manufacturing a multi-pair transmission cable in one embodiment includes a first twisting step and a second twisting step. In the first twisting step, a pair of electric wires are twisted in a first direction to form a twisted pair. In the second twisting step, a plurality of the twisted pairs are twisted in a second direction opposite to the first direction to form a cable assembly. In the second twisting step, the plurality of twisted pairs are twisted in the second direction while being untwisted.

[0018] Effects of the Invention

[0019] According to the present invention, it is possible to realize a multi-pair transmission cable in which degradation of transmission characteristics is prevented or suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a cross-sectional view of a multi-pair transmission cable according to one embodiment.

[0021] Figure 2 It is a process diagram showing a method for manufacturing a multi-pair transmission cable according to one embodiment.

[0022] Figure 3 It is a diagram showing the measurement results of the transmission characteristics of a multi-pair transmission cable according to one embodiment.

[0023] Figure 4 is a cross-sectional view showing a multi-pair transmission cable according to another embodiment.

[0024] Figure 5 This is a diagram showing the measurement results of the transmission characteristics of a multi-pair transmission cable according to another embodiment.

[0025] Description of Reference Numerals

[0026] 1A, 1B…multi-pair transmission cables, 10, 11, 12, 13, 14…twisted pairs, 15…wires, 16…center conductor, 17…insulator, 20…cable assembly, 30…separator, 40…shielding layer, 41…shielding tape, 42…shielding braid, 50…jacket. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that, in all the drawings used to illustrate the embodiments, the same reference numerals are used for the same or substantially the same configurations and elements. In addition, in principle, the configurations and elements that have been described once will not be described repeatedly.

[0028] <Implementation Method 1>

[0029] <Overview of Multi-Pair Transmission Cable>

[0030] Figure 1 1 is a cross-sectional view of a multi-pair transmission cable 1A of the present embodiment. The multi-pair transmission cable 1A has a cable assembly 20 composed of a plurality of twisted pairs 10. More specifically, the multi-pair transmission cable 1A has a cable assembly 20 composed of four twisted pairs 11, 12, 13, and 14. That is, the multi-pair transmission cable 1A is a 4-pair transmission cable (4-pair LAN cable).

[0031] Around the cable assembly 20 , a separator 30 , a shielding tape 41 , a shielding braid 42 , and a sheath 50 are provided in this order from the radially inner side toward the radially outer side.

[0032] <Twisted Pair Cable>

[0033] Each twisted pair 10 is a twisted pair cable (two-wire cable) having a pair of twisted electric wires 15. Each electric wire 15 is an insulated electric wire having a center conductor 16 and an insulator 17 covering the center conductor 16.

[0034] In each twisted pair 10, a pair of electric wires 15 are twisted in a first direction. From another perspective, each twisted pair 10 is composed of a pair of electric wires 15 twisted in a first direction.

[0035] Figure 1 The pairs of wires 15 shown are Figure 1 In the following description, the twisting direction (first direction / left direction) of the pair of electric wires 15 in each twisted pair 10 may be referred to as the "twisting direction".

[0036] It should be noted that although Figure 1 Although simplified in FIG. 1 , the center conductor 16 is formed of a plurality of copper wires. In addition, the insulator 17 is formed of polyethylene.

[0037] <Cable assembly>

[0038] The cable assembly 20 is a bundle of four twisted wire pairs 11, 12, 13, 14. The four twisted wire pairs 11, 12, 13, 14 constituting the cable assembly 20 are twisted in a second direction opposite to the twisting direction.

[0039] Right now, Figure 1 The four twisted pairs 11, 12, 13, and 14 shown are Figure 1 In the following description, the twisting direction (second direction / right direction) of the four twisted pair wires 11, 12, 13, 14 in the cable assembly 20 may be referred to as the "aggregate twisting direction".

[0040] In this way, in the multi-pair transmission cable 1A of this embodiment, the twisting direction is opposite to the collective twisting direction. More specifically, the four twisted pairs 11, 12, 13, 14 constituting the cable assembly 20 are twisted clockwise, while the pair of wires 15 constituting each twisted pair 11, 12, 13, 14 are twisted counterclockwise.

[0041] <Separator>

[0042] The separator 30 is made of polyethylene and covers the cable assembly 20. In other words, the separator 30 is a coating layer around which the four twisted pair wires 11, 12, 13, and 14 are wrapped.

[0043] <Shielding layer>

[0044] As described above, the shielding tape 41 and the shielding braid 42 are provided around the cable assembly 20. The shielding tape 41 is a PET (Poly Ethylene Terephthalate) tape on the surface of which a metal such as aluminum is vapor-deposited. From another perspective, the shielding tape 41 is a laminated tape in which a metal film is laminated on one side of a PET film.

[0045] The shielding tape 41 is wound around the separator 30 to cover the separator 30. More specifically, the shielding tape 41 is wound longitudinally around the outer circumference of the separator 30. However, the shielding tape 41 may be wound in an overlapping manner with a predetermined overlapping width.

[0046] The shielding braid 42 is formed into a cylindrical shape (sleeve shape, tube shape) by conductive wires such as copper wires and aluminum wires, resin wires covered with a metal film, etc. The shielding braid 42 is placed on the shielding tape 41 and covers the shielding tape 41 .

[0047] As a result, the shielding layer 40 having a double structure is formed by the shielding tape 41 and the shielding braid 42. However, the shielding layer 40 may be formed by either the shielding tape 41 or the shielding braid 42. That is, the shielding layer 40 may be a single layer or a multi-layer.

[0048] <Sheath>

[0049] The sheath 50 is made of polyethylene and forms the outermost layer of the multi-pair transmission cable 1A. From another perspective, the cable assembly 20 is covered by the sheath 50 , and the separator 30 and the shielding layer 40 are interposed between the cable assembly 20 and the sheath 50 .

[0050] <Manufacturing method>

[0051] Next, an example of a method for manufacturing the multi-pair transmission cable 1A having the above-described configuration will be described. Figure 2 It is a process diagram showing a method of manufacturing the multi-pair transmission cable 1A.

[0052] Figure 2 The first twisting process (step 1) shown is to form Figure 1 The process of twisting the twisted pair wire 10 shown in FIG. 1 is as follows. In the first twisting process, the pair of wires 15 are twisted in a first direction at a predetermined pitch. In other words, the pair of wires 15 are twisted to the left at a predetermined pitch.

[0053] Figure 2 The second twisting process (step 2) shown is to form Figure 1 In the second twisting step, four twisted pairs 10 formed in the first twisting step are prepared. Figure 1 The twisted pairs 11, 12, 13, 14 are shown.

[0054] Next, the twisted wire pairs 11, 12, 13, 14 are twisted in the second direction at a predetermined pitch using a twisting machine. In other words, the twisted wire pairs 11, 12, 13, 14 are twisted rightward at a predetermined pitch.

[0055] However, in the second twisting step, the twisted wire pairs 11, 12, 13, 14 are twisted while being untwisted at an untwisting rate of 100%. Specifically, while the twisting machine that twists the four twisted wire pairs 11, 12, 13, 14 rotates one revolution, the bobbin that successively unwinds the twisted wire pairs 11, 12, 13, 14 is rotated one revolution in the direction opposite to the rotation direction of the twisting machine.

[0056] If detwisting is performed while the twisting direction (collective twisting direction) in the second twisting process is the same as the twisting direction (torsion direction) in the first twisting process, a force (torsion) in the opposite direction to the torque direction is applied to the twisted pair 11, 12, 13, 14, and the twist may be untied.

[0057] However, the twisting direction (collective twisting direction) in the second twisting step of the present embodiment is opposite to the twisting direction (twist direction) in the first twisting step. Therefore, even if untwisting is performed in the second twisting step, a force (twist) in the opposite direction to the twisting direction will not be applied to the twisted pair wires 11, 12, 13, 14. Therefore, there is no worry that the twist of the twisted pair wires 11, 12, 13, 14 will be opened in the second twisting step. In other words, there is no worry that the twist pitch of the twisted pair wires 11, 12, 13, 14 will be extended in the second twisting step.

[0058] Figure 2 The separator coating process (step 3) shown is Figure 1 The separator 30 shown in the figure is formed around the cable assembly 20. In the separator covering step, a molten resin material is extruded around the cable assembly 20 to form a resin layer covering the cable assembly 20.

[0059] Figure 2 The shielding layer forming step (step 4) shown is to form Figure 1 In the shield layer forming step, a shield tape 41 is longitudinally wound around the separator 30 covering the cable assembly 20. Then, a shield braid 42 is covered on the shield tape 41.

[0060] Figure 2 The coating process (step 5) shown is to form Figure 1 In the coating step, the molten resin material is extruded around the shield layer 40 to form a resin layer covering the shield layer 40. That is, the cable assembly 20 is extruded and coated via the separator 30 and the shield layer 40. It should be noted that, as described above, the resin material used in this embodiment is polyethylene.

[0061] The inventors of the present application measured the transmission characteristics of the multi-pair transmission cable 1A of the present embodiment and found that Figure 3 In this measurement, the multi-pair transmission cable 1A of the present embodiment and another multi-pair transmission cable as a comparative example were prepared, and the near-end crosstalk attenuation of both cables was measured.

[0062] The multi-pair transmission cable prepared as a comparative example has the same or substantially the same configuration as the multi-pair transmission cable 1A of the present embodiment except that the collective twisting direction and the pair twisting direction are the same.

[0063] From another perspective, the multi-pair transmission cable prepared as a comparative example is Figure 2 The multi-pair transmission cable is manufactured by changing the twisting direction (collective twisting direction) of the twisted pair wires in the second twisting step (step 2) to the first direction.

[0064] The measuring device used was "Veda 2004DT" manufactured by AESA Process Cortaillod Co., Ltd. The measuring method was based on the IEC 61935-1 standard.

[0065] The measurement results show that the near-end crosstalk attenuation of the multi-pair transmission cable 1A of the present embodiment is not lower than the standard value of Category 5e (Cat.5e), but the near-end crosstalk attenuation of the multi-pair transmission cable prepared as a comparative example is lower than the standard value of Category 5e (Cat.5e) in a part of the frequency band.

[0066] Furthermore, in order to confirm that the manufacturing method of the present embodiment can prevent the twist pitch of the twisted pair from being elongated, the inventors of the present application conducted the following examination and obtained the results shown in Table 2.

[0067] In this inspection, a cable assembly manufactured as follows was used as the inspection object. Figure 2 The first twisting process (step 1) shown forms four twisted pairs (No. 1 to No. 4). It should be noted that the twisting directions of the twisted pairs are the same (first direction), but the twist pitches of the twisted pairs are intentionally staggered to deal with crosstalk.

[0068] Next, implement Figure 2 In the second twisting step (step 2) shown, four twisted pair wires (No. 1 to No. 4) are twisted in the second direction while being untwisted at an untwisting rate of 100% to form a cable assembly.

[0069] Then, for the four twisted pairs (No. 1 to No. 4) constituting the cable assembly, the twist pitches at two different locations (point a and point b) were measured, and the average value (mm) was calculated. Furthermore, the ratio of the calculated average value to the design value (mm) (average value / design value) was calculated as the elongation (%).

[0070] [Table 2]

[0071]

[0072] In this inspection, the average value of the elongation of the twist pitch of the four twisted pair wires (No. 1 to No. 4) was less than 105%.

[0073] <Implementation Method 2>

[0074] Figure 4 1B is a cross-sectional view of a multi-pair transmission cable 1B according to the present embodiment. The multi-pair transmission cable 1B has the same or substantially the same structure as the multi-pair transmission cable 1A according to the first embodiment.

[0075] More specifically, the multi-pair transmission cable 1B of the present embodiment has a cable assembly 20 composed of four twisted pairs 11, 12, 13, 14. Also, around the cable assembly 20, a separator 30, a shielding tape 41, a shielding braid 42, and a sheath 50 are sequentially provided from the radial inside to the radial outside.

[0076] The multi-pair transmission cable 1B of the present embodiment is manufactured by the same or substantially the same manufacturing method as the multi-pair transmission cable 1A of the first embodiment. More specifically, the multi-pair transmission cable 1B of the present embodiment is manufactured by including Figure 2 It should be noted that, regarding Figure 2 The details of each step shown are as already described.

[0077] On the other hand, the multi-pair transmission cable 1B of the present embodiment is different from the multi-pair transmission cable 1A of the first embodiment in the following points.

[0078] In the multi-pair transmission cable 1B of the present embodiment, the thickness of the insulator 17 is different in each twisted pair 10. As described above, each twisted pair 10 has a pair of electric wires 15, and each electric wire 15 has a central conductor 16 and an insulator 17.

[0079] In the multi-pair transmission cable 1B, the thickness of the insulator 17 of the electric wire 15 constituting each twisted pair 10 is different. Specifically, the thickness (t1) of the insulator 17 of the electric wire 15 constituting the twisted pair 11 is 0.259 mm, and the thickness (t2) of the insulator 17 of the electric wire 15 constituting the twisted pair 12 is 0.229 mm. In addition, the thickness (t4) of the insulator 17 of the electric wire 15 constituting the twisted pair 14 is 0.229 mm, and the thickness (t3) of the insulator 17 of the electric wire 15 constituting the twisted pair 13 is 0.235 mm.

[0080] From another perspective, the thicknesses ( t2 , t4 ) of insulator 17 of wire 15 constituting twisted pair 12 and insulator 17 of wire 15 constituting twisted pair 14 are approximately 88.5% of the thickness ( t1 ) of insulator 17 of wire 15 constituting twisted pair 11 .

[0081] In addition, the thickness (t3) of the insulator 17 of the electric wire 15 constituting the twisted pair 13 is about 90.8% of the thickness (t1) of the insulator 17 of the electric wire 15 constituting the twisted pair 11. It should be noted that in the multi-pair transmission cable 1A, the insulator 17 of the electric wire 15 has the same thickness (0.238 mm) in all the twisted pairs 10.

[0082] The inventors of the present application measured the transmission characteristics of the multi-pair transmission cable 1B of the present embodiment under the same conditions and method as those of the first embodiment, and obtained Figure 5 The measurement results are shown in FIG. 1 . The measurement results show that the near-end crosstalk attenuation of the multi-pair transmission cable 1B of the present embodiment does not fall below the standard value of Category 5e (Cat.5e). Figure 5 , for comparison, the measurement results of a plurality of pairs of transmission cables 1A are also described.

[0083] The use of the multi-pair transmission cables 1A and 1B is not particularly limited. The multi-pair transmission cables 1A and 1B are, for example, laid in a railway vehicle, a car, etc. The multi-pair transmission cables laid in a railway vehicle or a car vibrate as the railway vehicle or the car moves. Therefore, when manufacturing the multi-pair transmission cables laid in a railway vehicle or a car, it is desirable that no deformation (strain) remains in the twisted pair. That is, it is desirable to perform back-twisting to twist the twisted pair.

[0084] Therefore, the multi-pair transmission cables 1A and 1B of the present embodiment, which prevent or suppress the elongation of the twist pitch due to back-twisting, are particularly suitable for use in railway vehicles and automobiles.

[0085] The present invention is not limited to the above-mentioned embodiment, and various changes can be made within the scope of the main purpose. For example, the first direction (twist direction) is not limited to the left direction, and the second direction (collective twist direction) is not limited to the right direction. That is, the twist direction in the above-mentioned embodiment can be changed to the right direction, and the collective twist direction can be changed to the left direction.

[0086] Figure 2 The untwisting rate in the second twisting step is not limited to 100%, and may be less than 100%. However, the higher the untwisting rate, the easier it is for the twist of the twisted pair 10 to be untwisted, and the more difficult it is for the twisted pair 10 to be deformed.

[0087] Therefore, the back-twist rate in the second twisting process is preferably 50% or more and 100% or less. From another perspective, by setting the back-twist rate to 50% or more and 100% or less and setting the collective twisting direction to be opposite to the twisting direction, the twisted pair 10 can be prevented from being deformed and the twisting of the twisted pair 10 can be prevented from being opened.

[0088] Figure 1 , Figure 4 The cable assembly 20 shown may also include an interposer (e.g., a cross interposer). Figure 2 In the second twisting step (step 2) shown, the twisted pair wires 11, 12, 13, and 14 may be twisted together with an intermediary.

[0089] Also available in Figure 1 , Figure 4 A shielding layer is provided around each twisted pair 10 shown. In this case, Figure 1 , Figure 4 The shielding layer 40 shown may be omitted or retained.

[0090] The number of twisted pair wires 10 included in the cable assembly 20 can be increased or decreased as appropriate. The materials of the central conductor 16 and the insulator 17 of the electric wire 15 can be changed as appropriate. In addition, the material of the sheath 50 can also be changed as appropriate.

Claims

1. A method for manufacturing a multi-pair transmission cable, wherein the multi-pair transmission cable comprises a cable assembly consisting of a plurality of twisted pair cables, the method comprising: A first twisting step of twisting a pair of electric wires in a first direction to form the twisted pair; as well as In a second twisting step, the plurality of twisted pairs are twisted together in a second direction opposite to the first direction to form the cable assembly. In the second twisting step, the plurality of twisted pair wires are twisted in the second direction while being untwisted.

2. The method for manufacturing a multi-pair transmission cable according to claim 1, wherein: The untwisting rate in the second twisting step is 50% or more and 100% or less.

3. The method for manufacturing a multi-pair transmission cable according to claim 1, wherein: The method further includes a shielding layer forming step of covering the cable assembly with at least one of a shielding tape and a shielding braid.

4. The method for manufacturing a multi-pair transmission cable according to claim 1, wherein: In the second twisting step, the four twisted pair wires are twisted in the second direction to form the cable assembly.

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