Cable and method for manufacturing cable

Abstract

To provide a cable which is lightweight and improved in ease of bending and ease of shaping after bending, and to provide a method of manufacturing the cable.SOLUTION: The cable includes a plurality of aluminum wires twisted together and having a cross-sectional area of Dmm2, the cable having a total length of 1000mm is held in a horizontal state at a portion where a length from the other end is a length predetermined according to the cross-sectional area, and a weight having a load predetermined according to the cross-sectional area is attached to the other end. When a lowering amount (unit: mm) of the other end after 30 seconds is measured as a deflection amount under load, a lowering amount (unit: mm) of the other end after 30 seconds from removal of the weight is measured as a deflection amount after load release, and a sum of the deflection amount under load and the deflection amount after load release is calculated as an index value, the index value is within a range of a calculated value of 2.4 * D + 305 or more and a calculated value of 1.3 * D + 940 or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a cable and a method for manufacturing a cable. [Background technology]

[0002] The routing of electric wires and cables (hereinafter referred to as "cables") used in low-voltage mains, distribution boards, etc., often requires work in confined spaces, and the design constraints of the distribution boards often make the routing extremely difficult. Even in such difficult conditions, cables are bent and installed by hand. Furthermore, due to the aging of construction workers and labor shortages, the inconvenience and fatigue experienced when extending cables have become a problem. For this reason, cables are required to be lightweight, easy to bend, and easy for workers to maintain the shape they have been bent into, i.e., easy to shape and easy to handle.

[0003] To achieve good cable handling, the specific gravity is 8.89g / cm 3 Instead of copper, which has a specific gravity of 2.7 g / cm 3 Aluminum conductors (hereinafter also referred to as aluminum conductors), which are lighter than copper, have come to be used. Patent Document 1 proposes a cable that is safe and easy to install by improving the ease of shaping the cable after bending and by suppressing the cable's rebound. This cable improves installation workability.

[0004] However, the cable described in Patent Document 1 has room for further improvement in ease of bending and shaping compared to cables using copper conductors. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-97277 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a cable that is lightweight and has improved bendability and ease of shaping after bending, and a method for manufacturing the cable. [Means for solving the problem]

[0007] The inventor of the present invention discovered that when an index value calculated for a cable using a specified test method is within a specified range, the cable is lightweight and has improved bendability and reshapeability after bending, and has made the invention described below.

[0008] The cable according to the present invention is characterized as follows. Multiple strands conforming to JIS C3108 electrical hard aluminum wire are twisted together and the cross-sectional area is Dmm 2 A cable having a conductor in which At room temperature, The cable is straightened and has a total length of 1000 mm. A portion of the cable that is on one end side of the cable and is a predetermined distance from the other end of the cable according to the cross-sectional area is held horizontally. a weight having a load predetermined according to the cross-sectional area is attached to the other end; The amount of descent (unit: mm) of the other end after 30 seconds was measured as the amount of deflection under load. After measuring the deflection amount under the load, the amount of descent (unit: mm) of the other end 30 seconds after removing the weight is measured as the deflection amount after the load is released. When the sum of the deflection amount under load and the deflection amount after the load is released is calculated as an index value, The index value is within the range of not less than the calculated value of 2.4×D+305 and not more than the calculated value of 1.3×D+940. cable.

[0009] The method for manufacturing a cable according to the present invention is characterized as follows. Multiple strands conforming to JIS C3108 electrical hard aluminum wire are twisted together and the cross-sectional area is Dmm 2 A method for manufacturing a cable having a conductor comprising: At room temperature, The cable is straightened and has a total length of 1000 mm. A portion of the cable that is on one end side of the cable and is a predetermined distance from the other end of the cable according to the cross-sectional area is held horizontally. a weight having a load predetermined according to the cross-sectional area is attached to the other end; The amount of descent (unit: mm) of the other end after 30 seconds was measured as the amount of deflection under load. After measuring the deflection amount under the load, the amount of descent (unit: mm) of the other end 30 seconds after removing the weight is measured as the deflection amount after the load is released. The sum of the deflection amount under the load and the deflection amount after the load is released is calculated as an index value; If the index value is not within the range of 2.4×D+305 or more and 1.3×D+940 or less, the cross-sectional area of ​​each of the plurality of wires is reduced and the number of wires is increased to manufacture a cable in which the index value falls within the range. Cable manufacturing method. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a cable that is lightweight and has improved bendability and ease of reshaping after bending, and a method for manufacturing the cable.

[0011] The present invention has been briefly described above. The details of the present invention will become clearer by reading the following detailed description of the invention (hereinafter referred to as "embodiments") with reference to the accompanying drawings. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a model diagram showing a test device used to evaluate the cable of this embodiment. [Figure 2]FIG. 2 is a graph showing the relationship between the distance from the fulcrum to the other end and the weight. [Figure 3] FIG. 3 is a graph showing the threshold values ​​of the index values ​​for each size. [Figure 4] FIG. 4 is a model diagram showing a cross section of a twisted conductor included in a cable of a comparative example. [Figure 5] FIG. 5 is a model diagram showing a cross section of a stranded conductor included in the cable of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0014] The cable of this embodiment is made of a plurality of strands conforming to JIS C3108 hard aluminum wire for electrical use, twisted together, and has a cross-sectional area of ​​Dmm 2 and the index value calculated using a specified test method described below is within the range of 2.4×D+305 or more and 1.3×D+940 or less.

[0015] This cable is lightweight, highly flexible, and easy to shape, and can maintain its bent shape. This makes it extremely easy to handle when wiring. In addition, this cable is easy to shape and has little rebound, making it safe and secure to cut and install. Furthermore, the use of this cable improves the ease of wiring in tight spaces, reducing the burden on construction workers and shortening work time.

[0016] (Test Method) A cable testing method will be described with reference to Fig. 1. In this testing method, a testing device 21 shown in Fig. 1 is used to evaluate the ease of bending a cable, that is, its softness and ease of shaping (forming).

[0017] The test device 21 is configured with a table 22 having a predetermined height, a cable holder 23 provided on the table 22, a weight 24, and a deflection measurement jig (not shown). The cable holder 23 holds one end of a cable 25 as a sample and its vicinity. The cable 25 has a conductor with a cross-sectional area of ​​D (mm 2 ) and has a total length of 1000 mm. Such cable 25 is held horizontally at a portion where the distance (cable length) L to the other end is determined in advance according to the cross-sectional area of ​​the conductor, with cable holder 23 as the fulcrum. Weight 24 attached to the other end of cable 25 applies a load X (N) that is determined in advance according to the cross-sectional area of ​​the conductor. Cable 25 is straightened with any curling removed, and is stored for 24 hours or more at room temperature within ±5°C of the test temperature of 23°C.

[0018] Table 1 shows the cross-sectional area of ​​the conductor D (mm 2 1 is a table showing an example of the correspondence between the length of the conductor, the distance L (mm) from the fulcrum to the other end, and the load X (N). As shown in Table 1, the distance L from the fulcrum to the other end and the load X are each predetermined according to the cross-sectional area D of the conductor.

[0019] [Table 1]

[0020] Below, the cross-sectional area D of the conductor is 250 mm 2 In calculating the index value, first, a weight 24 is attached to the other end of the cable 25 as shown in FIG. 1(a). The cable 25 has a conductor cross-sectional area D of 250 mm 2Therefore, as shown in Table 1, the cable is held horizontally at a point where the distance L to the other end is 720 mm, with the cable holding part 23 as the fulcrum, and a weight 24 with a load X of 80 N is attached to the other end. The measurer measures the amount of deflection of the cable 25 (amount of deflection under load) 30 seconds after attaching the weight 24, i.e., the amount of descent (unit: mm) of the other end. The greater the amount of descent of the other end, the easier the cable 25 is to bend (with less force), i.e., the softer the cable 25 is. The ability of the cable 25 to bend with less force reduces the burden on the worker and indicates that workability and construction can be improved.

[0021] After measuring the amount of descent of the other end, as shown in Figure 1(b), the weight 24 is removed, and the amount of deflection (amount of deflection after load release (unit: mm)) is measured 30 seconds after the load is released. By removing the weight 24, the cable 25 bounces back, and the position of the terminal (other end) rises. The closer the amount of deflection after load release is to the amount of descent of the other end (amount of deflection under load), the easier it is to shape the cable 25 when bending it.

[0022] The sum of the deflection amount under load and the deflection amount after the load is released, measured in this manner, is calculated as an index value. The larger this index value, the softer the cable 25 is and the easier it is to shape it. The difference between the deflection amount under load and the deflection amount after the load is released can indicate the ease of shaping the cable, but in this embodiment, the sum of the deflection amount under load and the deflection amount after the load is released is used as the index. By using the sum of the deflection amount under load and the deflection amount after the load is released as the index, it is possible to evaluate both "flexibility" and "ease of shaping," i.e., workability.

[0023] If the cross-sectional area D of the conductor is, for example, 14 mm 2In this case, cable 25 is held horizontally so that the part 520 mm from the other end is at the end of cable holder 23 (the right end in FIG. 1), and a weight with a load X of 3 N is attached to the other end. Then, as described above, the amount of deflection under load and the amount of deflection after the load is released are measured, and the sum of these is calculated as the index value. When evaluating other cables, similarly, referring to Table 1, the distance L and load X corresponding to the cross-sectional area D can be used.

[0024] The cross-sectional area of ​​the conductor D (mm 2 ), the distance L (mm) from the fulcrum to the other end, and the load X (N) can be expressed by the following calculation formula (1). X=3.6×L×D / 10000 (1) As shown in equation (1), the load X is set to be proportional to the product of the cross-sectional area D and the distance L.

[0025] Cross-sectional area D is 14 mm 2 A graph of calculation formula (1) in this case is shown in Figure 2. As shown in Figure 2, the distance L from the fulcrum to the other end and the load X are predetermined according to the cross-sectional area D of the conductor, so distance L and load X other than those shown in Table 1 can be used according to the cross-sectional area D of the conductor.

[0026] The higher the index value calculated as above, the softer and easier it is to shape, meaning that workability is high. However, if the index value is too high, the conductor strength may be insufficient. Also, if the index value is low, workability decreases. Taking these factors into consideration, a graph showing the upper and lower limits of the appropriate range of index values ​​is shown in Figure 3.

[0027] Line L1 in Figure 3 indicates the upper limit of the index value. The upper limit of the index value is the calculated value of 1.3 x D + 940. The upper limit of the index value is set as the value that ensures the strength of the conductor. Cables (electric wires) must comply with the provisions of the Electrical Appliance and Material Safety Act. Specifically, they must meet the characteristics and equivalent characteristics stipulated in the Ministerial Ordinance Prescribing Technical Standards for Electrical Appliances (Appendix 1) (see "Explanation of Technical Standards for Electrical Appliances (Revised August 2021)" compiled by the Electrical Appliance and Material Research Committee and written by the Japan Electric Association, December 22, 2021, Appendix 1. hereinafter referred to as "Technical Standards"). The Technical Standards stipulate the standard value at which a cable will not break in the "tensile test of a conductor" specified in JIS C 3002. The Technical Standards stipulate the maximum value at which a cable with a cross-sectional area of ​​100 mm 2 Since there are regulations only for wires up to this size, for wires with a larger cross-sectional area, the standard value can be set so that it meets the same level of standards as the technical standards. For example, the tensile load (N) for a cross-sectional area of ​​D x 196 can be set as the standard value.

[0028] If the index value is equal to or less than the calculated value of 1.3 x D + 940, the strength of the conductor is guaranteed and the cable (electric wire) meets the characteristics specified in the technical standards and equivalent characteristics, so breakage will not occur under normal usage conditions.

[0029] Line L2 in Figure 3 indicates the lower limit of the index value. The lower limit of the index value is the calculated value of 2.4 x D + 305. The lower limit of the index value is set as a value that ensures workability. The lower the index value, the worse the workability, but as long as it does not fall below the index value for copper wires of a similar cross-sectional area, aluminum wires can maintain the advantages of being lightweight and easy to handle, as well as the same level of softness and ease of shaping (workability) as copper wires.

[0030] The inventors have determined that the cross-sectional area of ​​the conductor D (mm 2 We created multiple cables of each type with different diameters, and calculated the average value [mm], maximum value [mm], minimum value [mm], upper variation [%], and lower variation [%] for the index value of each cable. The results are shown in Table 2.

[0031] [Table 2]

[0032] As shown in Table 2, each cross-sectional area D (mm 2 ) cables, the average variation in index values ​​was 6%. Therefore, we outputted calculation formulas that would keep the variation in index values ​​within 6% on both the upper and lower limits. Specifically, we obtained calculation formula (2) that would result in index value F being -6% of the calculated value (1.3 × D + 940) for the upper limit, and calculation formula (3) that would result in index value F being +6% of the calculated value (2.4 × D + 305) for the lower limit. F=1.2×D+883 (2) F=2.5×D+323 (3)

[0033] Line L3 in Figure 3 is the graph result of formula (2), and line L4 in Figure 3 is the graph result of formula (3). Formula (2) indicates the upper limit when considering variation, and formula (3) indicates the lower limit when considering variation. When the index value is within the range from the lower limit to the upper limit when considering variation, variation in the index value is suppressed, which contributes to stabilizing the quality of the product (cable).

[0034] The cables described above may be aluminum power cables conforming to JCS 4348, aluminum power cables with wires conforming to JCS 3346, 600V aluminum conductor vinyl-insulated vinyl sheath cables conforming to JCS 4347, or high-voltage aluminum conductor cross-linked polyethylene cables conforming to JCS 4523. Regardless of the cable type, if the index value is greater than or equal to 2.4 × D + 305 and less than or equal to 1.3 × D + 940, the cable has high flexibility, is easy to shape, and can maintain a bent shape. Because such cables use aluminum conductors, they are lighter than cables using copper conductors, yet offer the same or better ease of bending and shaping as cables using the same conductors.

[0035] (Cable manufacturing method) When manufacturing (designing) a cable with an aluminum conductor, the cross-sectional area D (mm2 By reducing the cross-sectional area per wire and increasing the number of wires so that the cross-sectional area D is approximately the same, it is possible to manufacture a cable in which the above-mentioned index value falls within a predetermined range. In other words, the index value of the cable falls within a range equal to or greater than the calculated value of 2.4 × D + 305 and equal to or less than the calculated value of 1.3 × D + 940. Hereinafter, when the cross-sectional area D is 250 mm 2 An example of the case will be explained.

[0036] FIG. 4 is a cross-sectional view of a stranded conductor included in a cable of the comparative example. The stranded conductor 101 shown in FIG. 4 has 61 strands 102. Each strand 102 has a diameter of 2.40 mm. The index value of the cable including this stranded conductor 101 is 771 mm, which is not within the appropriate range of 905 mm to 1265 mm. Therefore, the cross-sectional area (strand diameter) of each strand 102 is reduced to increase the number of strands. Specifically, as shown in FIG. 5, the number of strands 2 is set to 91. The diameter of each strand 2 is 1.87 mm, which is smaller than the cross-sectional area of ​​the strands 102. Table 3 shows the results of calculating the above-mentioned index values ​​for the cable including the stranded conductor 101 and the cable including the stranded conductor 1. In this example, the cable including the stranded conductor 1 and the cable including the stranded conductor 101 are 600V cross-linked polyethylene insulated vinyl sheath (CVT) cables with a single core and an outer diameter of 28.0 mm, conforming to JCS 4348 aluminum conductor cross-linked polyethylene cables.

[0037] [Table 3]

[0038] As shown in Table 3, when the wire diameter was reduced and the number of wires was increased, the index value increased, indicating that the cable's flexibility and ease of shaping were improved.

[0039] The present invention is not limited to the above-described embodiments, and can be appropriately modified, improved, etc. In addition, the material, shape, dimensions, numerical values, form, number, location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as they can achieve the present invention.

[0040] In the cable of this embodiment, the stranded conductor 1 can be obtained by, for example, producing wires (hard aluminum conductors) using pure aluminum as a raw material and twisting them together, but after twisting, annealing treatment may be performed. Examples of annealing treatment include pod annealing and continuous annealing.

[0041] The stranded conductor 1 is made up of wires 2 all having the same diameter, but may be formed by combining wires having two or more different diameters.

[0042] The shape of the twisted conductor 1 is preferably a circular twisted wire or a circular compressed twisted wire because it is easier to bend and more easily shaped, but is not necessarily limited to a circular shape.

[0043] The twist direction of the stranded conductor 1 is preferably alternate twist in each layer, and the outermost layer may be S twist or Z twist.

[0044] The above-mentioned twisted conductor 1 may be a cable that is individually insulated or further shielded. Alternatively, a cable may be formed by bundling a plurality of twisted conductors 1 and then insulating the bundled conductors, or a cable that is insulated and sheathed or further shielded. Furthermore, a plurality of such cables may be bundled together and then further coated.

[0045] Here, the features of the cable and the cable manufacturing method according to the above-described embodiment of the present invention will be briefly summarized and listed below in [1] to [4].

[0046] [1] A wire (2) conforming to JIS C3108 hard aluminum wire for electrical use and having a cross-sectional area of ​​D mm 2 A cable having a conductor (stranded conductor 1) which is At room temperature, The cable is straightened and has a total length of 1000 mm. A portion of the cable that is on one end side of the cable and is a predetermined distance from the other end of the cable according to the cross-sectional area is held horizontally. a weight having a load predetermined according to the cross-sectional area is attached to the other end; The amount of descent (unit: mm) of the other end after 30 seconds was measured as the amount of deflection under load. After measuring the deflection amount under the load, the amount of descent (unit: mm) of the other end 30 seconds after removing the weight is measured as the deflection amount after the load is released. When the sum of the deflection amount under load and the deflection amount after the load is released is calculated as an index value, The index value is within the range of not less than the calculated value of 2.4×D+305 and not more than the calculated value of 1.3×D+940. cable.

[0047] The cable having the configuration [1] above is lightweight, highly flexible, and easily shaped, and can maintain its bent shape. Therefore, this cable makes it extremely easy to handle when wiring. Furthermore, since this cable is easy to shape and has little rebound, it can be cut and installed safely and securely. Furthermore, the use of this cable improves the ease of wiring work in tight spaces, reducing the burden on construction workers and shortening work time.

[0048] [2] The index value is within the range of 2.5 × D + 323 or more and 1.2 × D + 883 or less. [1] The cable described in [1].

[0049] According to the cable having the configuration [2] above, the variation in the index value is suppressed, which contributes to the stability of product quality.

[0050] [3] The load is set to be proportional to the product of the cross-sectional area and the distance. [1] The cable described in [1].

[0051] With the cable having the configuration [3] above, the deflection amount under load and the deflection amount after the load is released can be measured using a weight of a load according to the cross-sectional area of ​​the conductor and the distance from the other end of the cable, and the index value can be calculated.

[0052] [4] Multiple strands conforming to JIS C3108 electrical hard aluminum wire are twisted together and the cross-sectional area is Dmm 2 A method for manufacturing a cable having a conductor comprising: At room temperature, The cable is straightened and has a total length of 1000 mm. A portion of the cable that is on one end side of the cable and is a predetermined distance from the other end of the cable according to the cross-sectional area is held horizontally. a weight having a load predetermined according to the cross-sectional area is attached to the other end; The amount of descent (unit: mm) of the other end after 30 seconds was measured as the amount of deflection under load. After measuring the deflection amount under the load, the amount of descent (unit: mm) of the other end 30 seconds after removing the weight is measured as the deflection amount after the load is released. The sum of the deflection amount under the load and the deflection amount after the load is released is calculated as an index value; If the index value is not within the range of 2.4×D+305 or more and 1.3×D+940 or less, the cross-sectional area of ​​each of the plurality of wires is reduced and the number of wires is increased to manufacture a cable in which the index value falls within the range. Cable manufacturing method.

[0053] According to the cable manufacturing method configured as described above in [4], it is possible to manufacture a cable that is lightweight, highly flexible, easy to shape, and able to maintain its bent shape. This cable makes it extremely easy to handle during wiring. Furthermore, since this cable is easy to shape and has little rebound, it can be cut and installed safely and securely. Furthermore, the use of this cable improves the ease of installation work in narrow spaces, reducing the burden on construction workers and shortening work time. [Explanation of symbols]

[0054] 1. Stranded conductor (conductor) 2 wires 21 Test equipment

Claims

1. A wire conforming to JIS C3108 hard aluminum wire for electrical use is twisted together and has a cross-sectional area of ​​D mm ２ A cable having a conductor in which At room temperature, The cable having a total length of 1000 mm and being straightened is held horizontally at one end of the cable at a distance from the other end of the cable that is a predetermined distance depending on the cross-sectional area, a weight having a load predetermined according to the cross-sectional area is attached to the other end; The amount of descent (unit: mm) of the other end after 30 seconds was measured as the amount of deflection under load. After measuring the deflection amount under the load, the amount of descent (unit: mm) of the other end 30 seconds after the weight was removed was measured as the deflection amount after the load was released. When the sum of the deflection amount under load and the deflection amount after the load is released is calculated as an index value, The index value is in the range of not less than the calculated value of 2.4×D+305 and not more than the calculated value of 1.3×D+940, cable.

2. The index value is in the range of not less than the calculated value of 2.5×D+323 and not more than the calculated value of 1.2×D+883. The cable of claim 1 .

3. The load is set to be proportional to the product of the cross-sectional area and the distance.

3. The cable according to claim 1 or 2.

4. A wire conforming to JIS C3108 hard aluminum wire for electrical use is twisted together and has a cross-sectional area of ​​D mm ２ A method for manufacturing a cable having a conductor comprising: At room temperature, The cable having a total length of 1000 mm and being straightened is held horizontally at one end of the cable at a distance from the other end of the cable that is a predetermined distance depending on the cross-sectional area, a weight having a load predetermined according to the cross-sectional area is attached to the other end; The amount of descent (unit: mm) of the other end after 30 seconds was measured as the amount of deflection under load. After measuring the deflection amount under the load, the amount of descent (unit: mm) of the other end 30 seconds after the weight was removed was measured as the deflection amount after the load was released. The sum of the deflection amount under the load and the deflection amount after the load is released is calculated as an index value; If the index value is not within the range of 2.4×D+305 or more and 1.3×D+940 or less, the cross-sectional area of ​​each of the plurality of wires is reduced and the number of wires is increased to manufacture a cable in which the index value falls within the range. Cable manufacturing method.

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