Insulated wire and method for producing the same, insulated wire with terminal and method for producing the same

Abstract

The present invention provides an insulated wire that can also withstand instantaneously applied stress and is less likely to break. An insulated wire (1) is disclosed, which has a conductor (2) formed by stranding a plurality of bare wires and a coating layer (3) covering the conductor (2). In the insulated wire (1), the bare wires are made of a certain copper alloy, the conductor (2) is composed of a central bare wire (2a) and a plurality of concentric bare wires (2b) concentrically arranged around it. The oil component adhering to the central bare wire (2a) is 6 μg / g or less relative to the mass of the central bare wire (2a). The stranding pitch of the conductor (2) is 5 to 10 mm and the cross-sectional area is 0.15 mm<supgt;2< / supgt; or less. The coating layer (3) is made of polyvinyl chloride resin, and the thickness of the coating layer (3) is 0.15 to 0.25 mm.

Description

Technical Field

[0001] The present invention relates to an insulated wire and a method for producing the same, and an insulated wire with a terminal and a method for producing the same. Background Art

[0002] Insulated wires having a conductor and a coating covering the conductor have long been used as power lines or signal lines for vehicles or industrial use. Recently, with the complex control or automation of vehicles and industrial machinery, there is a demand for thinner and stronger wires. Among insulated wires for vehicles, although a cross-sectional area of ​​0.35 mm 2 However, the development of insulated wires with thinner diameters is also being promoted.

[0003] For example, Patent Document 1 describes that in order to make the cross-sectional area of ​​the conductor approximately 0.22 mm 2 The composition of the copper alloy used for the conductor is adjusted.

[0004] Patent Document 2 describes reducing the amount of oil adhering to the surface of the central bare wire of the conductor in order to suppress buckling when the insulated wire is thinned.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 6134103

[0008] Patent Document 2: Japanese Patent No. 6864856 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] Here, generally speaking, insulated wires are rarely used alone, and terminals are connected to both ends of the insulated wires and connected to various devices via these terminals. In addition, when assembling automobiles or industrial machinery, or when using automobiles or industrial machinery, various devices are connected to the wires, and the equipment sometimes falls. As a result, stress in the direction of free fall is applied to the insulated wires instantly, and the wires sometimes break. If such a break occurs, the equipment is damaged or sufficient conduction cannot be achieved between the equipment. In the description of the insulated wires in the above-mentioned Patent Document 1 or Patent Document 2, there is no mention of resistance to such instantaneous stress.

[0011] A main object of the present invention is to provide an insulated wire that can withstand stress applied instantaneously and is less likely to break.

[0012] Solutions to the problem

[0013] In order to solve the above-mentioned problems, according to the present invention, there is provided an insulated wire having a conductor formed by twisting a plurality of bare wires and a coating layer covering the conductor, wherein:

[0014] The bare wire is composed of a copper alloy, which is an alloy containing one or more additional elements selected from the group consisting of Fe, Ti, Mg, Sn, Ag, Ni, In, Zn, Cr, Al, P, Be, Co and Si, and the remainder is composed of Cu and inevitable elements,

[0015] The amount of the added element in the copper alloy is 0.2 to 0.4% by mass.

[0016] The conductor is composed of a central bare wire and a plurality of concentric bare wires arranged concentrically around the central bare wire.

[0017] The amount of oil adhering to the central bare wire is 6 μg / g or less relative to the mass of the central bare wire.

[0018] The conductor has a twist pitch of 5 to 10 mm and a cross-sectional area of ​​0.15 mm 2 the following,

[0019] The coating layer is made of polyvinyl chloride resin.

[0020] The coating layer has a thickness of 0.15 to 0.25 mm.

[0021] Effects of the Invention

[0022] According to the present invention, it is possible to provide an insulated wire that can withstand stress applied instantaneously and is less likely to break. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A 1 is a schematic cross-sectional view showing an example of an insulated wire.

[0024] Figure 1B It is a schematic cross-sectional view showing another example of the insulated wire.

[0025] Figure 2 : is a flowchart schematically showing a method for manufacturing an insulated wire.

[0026] Figure 3 This is a side view showing an example of an insulated wire with a terminal. DETAILED DESCRIPTION

[0027] Hereinafter, preferred embodiments of the present invention will be described.

[0028] In the present specification, "to" indicating a numerical range includes an upper limit and a lower limit in the numerical range.

[0029] (Insulated wire)

[0030] The insulated wire according to the preferred embodiment of the present invention is very useful as a power line or a signal line for automobiles or industrial machinery.

[0031] like Figure 1A , Figure 1B As shown, the insulated wire 1 of this embodiment includes a conductor 2 formed by twisting a plurality of bare wires and a coating 3 for coating the conductor 2. The conductor 2 is made of a copper alloy described below, and the coating 3 is made of a resin described below.

[0032] like Figure 1A As shown in the embodiment, the conductor 2 is composed of one central bare wire 2a and six concentric bare wires 2b surrounding the central bare wire 2a in a concentric manner. However, the number of these bare wires is appropriately selected according to the application of the insulated wire 1, etc.

[0033] The conductor 2 may be Figure 1A As shown in FIG. 1 , a non-compressed conductor consisting of a plurality of bare wires twisted together may also be a conductor such as Figure 1B As shown, multiple bare wires are twisted together and then compressed into a compressed conductor of the desired shape.

[0034] The cross-sectional area or diameter of each bare wire is not particularly limited, but the total cross-sectional area of ​​each bare wire, that is, the cross-sectional area of ​​the conductor 2 is 0.15 mm 2 The cross-sectional area of ​​the conductor 2 is preferably 0.120 mm 2 Above and 0.140mm 2 Below, more preferably 0.125mm 2 Above and 0.134mm 2 According to the insulated wire 1 of the present embodiment, even if the cross-sectional area of ​​the conductor 2 is reduced to 0.15 mm 2 Even in the following manner, sufficient strength and conductivity to withstand use can be obtained.

[0035] The cross-sectional shape of the conductor 2 may be a substantially circular shape, an elliptical shape, or a polygonal shape, etc. The thickness of each bare wire constituting the conductor 2 may be the same or different, but is usually the same.

[0036] In the conductor 2, the central bare wire 2a and the concentric bare wires 2b arranged around it are twisted in a certain direction with the central bare wire 2a as the axis. The twist pitch at this time can be 5 to 10 mm, and more preferably 6 to 8 mm. The "twisting pitch" refers to the length of the conductor 2 required to rotate the conductor 2 360° with the center line as the axis.

[0037] If the twist pitch of the conductor 2 is 10 mm or less, when the coating 3 is formed around the conductor 2, the coating 3 is easily engaged with the conductor 2. As a result, not only the conductor 2 but also the coating 3 can function as a tension member. That is, when stress (tensile stress) is applied to the insulated wire 1 instantaneously, not only the conductor 2 but also the coating 3 can relieve the stress and suppress the breakage of the insulated wire 1. On the other hand, if the twist pitch of the conductor 2 is 5 mm or more, the adhesion between the conductor 2 and the coating 3 is not excessively increased, and when the conductor 2 is connected to a terminal, the coating 3 can be peeled off without leaving any trace.

[0038] Here, each bare wire of the conductor 2 is preferably a tempered bare wire. If each bare wire is tempered, both the strength and the elongation of the conductor 2 can be achieved.

[0039] Furthermore, the amount of oil adhering to the central bare wire 2a of the conductor 2 is 10 μg / g or less, more preferably 6 μg / g or less, relative to the mass of the central bare wire 2a.

[0040] The less the amount of oil adhering to the center bare wire 2a, the more easily the affinity between the conductor 2 and the coating layer 3 is improved. As a result, the coating layer 3 is easy to enter the gap between the bare wires, or the coating layer 3 is easy to adhere to the surface of the conductor 2. Therefore, when stress is applied to the insulated wire 1 instantaneously, the breakage of the insulated wire 1 is easily suppressed.

[0041] It should be noted that the oil content of the concentric bare wires 2b of the conductor 2 is excluded from the measurement object here because: (i) when the coating layer 3 is formed on the conductor 2, additives such as plasticizers contained in the resin composition of the coating layer 3 adhere to the concentric bare wires 2b during the manufacturing process and the correct oil content cannot be measured, or conversely, (ii) when the coating layer 3 is removed from the conductor 2, the attached oil is also removed from the concentric bare wires 2b and the correct oil content cannot be measured. That is, here, if the oil content of the central bare wire 2a is measured and controlled, it is reflected in the number of concentric bare wires 2b, and as a result, the oil content of the entire conductor 2 can be controlled, and the gap where the coating layer 3 enters the bare wire or the adhesion of the coating layer 3 to the surface of the conductor 2 can be quantified.

[0042] The amount of oil adhering to the central bare wire 2a of the conductor 2 can be determined by, for example, the following method.

[0043] The insulated wire 1 is cut into a predetermined length, and the coating 3 is removed with a special tool such as a stripper. Then, the conductor 2 is pulled out. Then, the center bare wire 2a is taken out from the conductor 2, and the oil content is extracted with an extraction solvent (for example, a trimer of chlorotrifluoroethylene). This operation is repeated several times, and the oil content in the extract is determined with an oil concentration meter. Then, the obtained oil content can be calculated by dividing it by the mass of the center bare wire 2a provided for measurement. The amount of oil attached to the center bare wire 2a can be adjusted according to the type or time of the treatment performed in the degreasing process of the conductor 2 in the manufacturing method of the insulated wire 1 described later.

[0044] Here, the copper alloy of each bare wire constituting the conductor 2 contains one or more additional elements selected from the group consisting of Fe, Ti, Mg, Sn, Ag, Ni, In, Zn, Cr, Al, P, Be, Co and Si, and the remainder is composed of Cu and inevitable elements.

[0045] The additive element may be only one, or may contain two or more. Usually, it is three or less. Among the above-mentioned additive elements, Mg and Sn are particularly preferred.

[0046] The amount of the additive element in the copper alloy is 0.2 to 0.4 mass %, preferably 0.25 to 0.35 mass %, and more preferably 0.28 to 0.32 mass %. If the amount of the additive element in the copper alloy is 0.2 mass % or more, the strength of the conductor 2 is improved, for example, the tensile strength is enhanced. On the other hand, if the amount of the additive element in the copper alloy is 0.4 mass % or less, the conductivity of the conductor 2 is easily improved.

[0047] Here, the conductivity of the conductor 2 is preferably 75% IACS (International Annealed Copper Standard) or more, and more preferably 80% IACS or more. If the conductivity of the conductor 2 is 75% IACS or more, the insulated wire 1 can be used for various purposes. The conductivity of the conductor 2 is a value calculated from the resistance value according to the Japanese Industrial Standard JIS H 0505. The resistance value is measured by the double bridge method using a conductor with a length of 500 mm. The conductivity of the conductor 2 can be adjusted, for example, by the type or amount of the above-mentioned additive element.

[0048] The strength of the conductor 2 is preferably 350 MPa to 450 MPa, more preferably 390 MPa to 430 MPa, and further preferably 400 MPa to 420 MPa. If the strength of the conductor 2 is within this range, the insulated wire 1 can be used for various purposes. The strength of the conductor 2 is a value measured by a universal testing machine (Autograph) manufactured by Shimadzu Corporation. The strength of the conductor 2 is adjusted according to the type or amount of the above-mentioned added elements, the degree of tempering, etc.

[0049] The elongation of the conductor 2 is preferably 5 to 10%, more preferably 8 to 10%, and further preferably 9 to 10%. If the elongation of the conductor 2 is within this range, the insulated wire 1 can be used for various purposes. The elongation of the conductor 2 is also a value measured by a universal testing machine (Autograph) manufactured by Shimadzu Corporation. The elongation of the conductor 2 is adjusted according to the type or amount of the above-mentioned added elements, the degree of tempering, etc.

[0050] On the other hand, the coating layer 3 is a layer that insulates and coats the conductor 2, and is a layer that contains a polyvinyl chloride resin. Usually, the coating layer 3 is formed by extrusion of an extruder, etc. The coating layer 3 may mainly contain a polyvinyl chloride resin, and may also contain a portion of components other than the polyvinyl chloride resin within the scope that does not impair the purpose and effect of the present embodiment. Compared with a coating layer containing a polypropylene resin, for example, the coating layer 3 containing a polyvinyl chloride resin sometimes has reduced adhesion to the conductor 2, but according to the present embodiment in which the twist pitch of the conductor 2 is controlled, the adhesion to the conductor 2 can be fully improved, and the insulated wire 1 can be made that can also withstand transient stress.

[0051] The thickness of the coating layer 3 is not particularly limited, but is usually preferably 0.15 mm to 0.25 mm, and more preferably 0.15 mm to 0.20 mm. If the thickness of the coating layer 3 is 0.15 mm or more, sufficient insulation is easily obtained, and further, as described above, when an instantaneous tensile stress is applied to the insulated wire 1, the coating layer 3 can also function as a tensile element. On the other hand, if the thickness of the coating layer 3 is 0.25 mm or less, the insulated wire 1 can be made thinner.

[0052] Here, the adhesion strength between the conductor 2 and the coating layer 3 is preferably 19 to 23 N (i) when the conductor 2 is a non-compressed conductor, and preferably 20 to 21 N (ii) when the conductor 2 is a compressed conductor and the compression degree is 3 to 4%. If the adhesion strength is above the respective lower limits, the adhesion becomes sufficient and the insulated wire 1 can be used for various purposes. On the other hand, if the adhesion strength is below the respective upper limits, the coating layer 3 can be easily removed when the insulated wire 1 is connected to a terminal or the like. The adhesion strength is measured in accordance with the Japanese Automotive Standards Organization standard JASO D618.

[0053] When the conductor 2 is a compressed conductor, the compression rate is preferably 3 to 4%. The compression rate of the conductor 2 is derived from the following formula.

[0054] Compression ratio = (conductor cross-sectional area before compression - conductor cross-sectional area after compression) / conductor cross-sectional area before compression × 100%

[0055] (Manufacturing method of insulated electric wire)

[0056] like Figure 2 As shown, the manufacturing method of the insulated wire 1 basically consists of the following steps: step S1 of preparing the conductor 2 by twisting a plurality of bare wires, step S2 of degreasing the conductor 2, step S3 of tempering the conductor 2, and step S4 of coating the conductor 2 with a polyvinyl chloride resin to form a coating layer 3.

[0057] In the conductor 2 preparation step S1 , for example, the copper alloy is cast to form a cast material and then processed into a wire shape to obtain each bare wire, but the manufacturing method is not limited to this.

[0058] In the conductor 2 preparation step S1, a plurality of bare wires are twisted at a twisting pitch of 5 to 10 mm, and the cross-sectional area is controlled to 0.15 mm 2 At this time, one bare wire is used as the central bare wire 2a, and six concentric bare wires 2b are arranged concentrically around it, and they are twisted at the above-mentioned twist pitch.

[0059] The obtained conductor 2 may be subjected to compression processing.

[0060] Examples of the compression method include a method of supplying the conductor 2 to a die and extracting it from the die, but the method is not limited to this.

[0061] In the degreasing step S2 of the conductor 2, degreasing is performed until the total amount of oil attached to the center bare wire 2a becomes 10 μg / g or less, preferably 6 μg / g or less relative to the total mass of the center bare wire 2a. If degreasing is performed until the total amount of oil becomes 6 μg / g or less, the affinity between each bare wire and the coating layer 3 covering it is improved. Furthermore, if degreasing is performed in this way, heat is easily uniformly transferred to each bare wire, and the coating layer 3 is easy to uniformly enter the gap between the bare wires or the coating layer 3 is easy to adhere to the surface of each bare wire.

[0062] The treatment method of the degreasing step S2 of the conductor 2 is not particularly limited, and for example, degreasing may be performed using an organic solvent or by heat treatment.

[0063] When degreasing is performed with an organic solvent, the type of organic solvent is appropriately selected according to the type of oil attached to the bare wire. For example, alcohol can be used. The method of treating with an organic solvent is not particularly limited, and for example, the bare wire may be immersed in an organic solvent or wiped with a cloth soaked in an organic solvent.

[0064] On the other hand, when degreasing is performed by heat treatment, it is preferably heated in the presence of an inert gas. The heating temperature or heating time is appropriately selected according to the type of oil attached to the bare wire. For example, a method of heating at 250 to 350° C. for 2 to 10 hours may be used.

[0065] In the tempering step S3 of the conductor 2, the temperature or time for tempering the conductor 2 is not particularly limited, but it is preferably performed within the range of 250 to 350°C for 2 to 10 hours. At this time, it is preferably heated in the presence of an inert gas such as a nitrogen stream. By tempering, the elongation and strength of the conductor 2 are both achieved. Furthermore, by tempering, the bare wire is given appropriate softness, so when the coating layer 3 is formed, the resin easily enters the gaps between the bare wires.

[0066] In the degreasing step S2 of the conductor 2 , a plurality of bare wires are degreased at once, but they may be degreased one by one. From the viewpoint of the manufacturing efficiency of the insulated wire 1 , it is preferable to degrease a plurality of bare wires at once.

[0067] The degreasing step S2 of the conductor 2 and the heat treatment step S3 of the conductor 2 may be performed before the bare wires are twisted in the preparation step S1 of the conductor 2, or the order may be changed or they may be performed simultaneously. For example, if the conductor 2 is heated at 250 to 350° C. for 2 to 10 hours, the degreasing step S2 of the conductor 2 and the heat treatment step S3 may be performed simultaneously.

[0068] The degreasing step S2 and the heat treatment step S3 of the conductor 2 can basically be performed at any time as long as they are performed after the bare wire is produced and before the insulating layer 3 is formed.

[0069] In the step S4 of forming the coating layer 3 , the coating layer 3 can be formed by extrusion processing of a polyvinyl chloride resin, etc. In this way, the above-mentioned insulated wire 1 in which the coating layer 3 is arranged around the conductor 2 can be obtained.

[0070] (Insulated wire with terminal)

[0071] The insulated wire with a terminal of this embodiment can be used for various wirings. For example, it can be used for wiring of various electrical devices such as equipment in automobiles and airplanes, and control equipment of industrial robots, etc. More specifically, it can be used for automobile wiring harnesses, etc.

[0072] like Figure 3 As shown, the insulated wire with a terminal includes an insulated wire 1 and a terminal 10 connected to an end of the insulated wire 1. In the insulated wire with a terminal, the terminal 10 may be connected to one end of the insulated wire 1 or to both ends.

[0073] The terminal 10 has, in order from one end, a female or male fitting portion 11 for connection to various devices, a wire barrel portion 12 for fixing the conductor 2 of the insulated wire 1 , and an insulating barrel portion 13 for supporting the coating 3 of the insulated wire 1 .

[0074] The fitting portion 11 may be a structure that can be connected to various devices and may be appropriately selected according to its type. In order to reliably connect the conductor 2 and the terminal 10 electrically and mechanically, the wire barrel portion 12 has a structure for compressing and fixing the conductor 2. The insulating barrel portion 13 has a structure for fully supporting and fixing the coating layer 3. These are the same as the structures of general terminals.

[0075] (Method for manufacturing insulated electric wire with terminal)

[0076] The method for producing an insulated wire with a terminal basically includes the steps of peeling off the coating 3 from the end of the insulated wire 1 to expose the conductor 2 , and connecting the terminal 10 to the exposed portion of the conductor 2 .

[0077] The method of stripping the coating 3 from the end of the insulated wire 1 to expose the conductor 2 is the same as a general method, and for example, the conductor 2 can be exposed using a dedicated tool such as a stripper.

[0078] The method of connecting the terminal 10 to the conductor 2 of the insulated wire 1 is the same as the general method. For example, the following method can be adopted: fix the coating 3 of the insulated wire 1 on the insulating barrel portion 13 of the terminal 10, and at the same time press the barrel portion 12 so that the exposed conductor 2 is crimped onto the barrel portion 12.

[0079] Note that this implementation plan will also contribute to Goal 9 of the Sustainable Development Goals (SDGs), which is an international standard for achieving a sustainable and better world by 2030, as proposed in the 2030 Agenda for Sustainable Development adopted at the United Nations Summit in September 2015, namely, "achieving resilient infrastructure, promoting inclusive and sustainable industrialization, and fostering innovation."

[0080] Example

[0081] (1) Sample preparation

[0082] (1.1) Sample 1

[0083] A copper alloy containing 0.3 mass % Sn and the remainder consisting of Cu and inevitable elements was continuously cast using a horizontal continuous casting machine having a graphite mold with a water cooling jacket on the outer periphery to produce a cast rod with a diameter of 12 mm. The cast rod was cold worked to obtain a plurality of bare wires with a diameter of about 0.16 mm.

[0084] Next, prepare 7 bare wires, one of which is used as the central bare wire, and the remaining 6 are used as concentric bare wires arranged concentrically around the central bare wire. Then, these bare wires are twisted at a twist pitch of 12 mm to form a conductor. The cross-sectional area of ​​the conductor is 0.13 mm 2 .

[0085] Then, the conductor was heat treated at 300° C. for 2 hours in a nitrogen gas flow (the conductor was degreased and tempered).

[0086] Then, a polyvinyl chloride resin was extruded from the die head of the extruder so as to cover the periphery of the conductor, thereby forming a coating layer around the conductor. The thickness of the coating layer was set to 0.2 mm.

[0087] (1.2) Samples 2 to 5

[0088] The twist pitch of the conductor was changed as shown in Table 1.

[0089] Samples 2 to 5 were prepared in the same manner as Sample 1 except for the above.

[0090] (1.3) Sample 11

[0091] Bare wires were prepared in the same manner as in the preparation of Sample 1 to prepare conductors having a twist pitch of 15 mm.

[0092] Then, the conductor was passed through the hole of the die and subjected to a circular compression process. The compression rate was set to 3%.

[0093] Then, the conductor was heat treated at 300° C. for 2 hours in a nitrogen gas flow (the conductor was degreased and tempered).

[0094] Sample 11 was prepared in the same manner as Sample 1 except for the above.

[0095] (1.4) Samples 12 to 16

[0096] The twist pitch of the conductor was changed as shown in Table 1.

[0097] Samples 12 to 16 were prepared in the same manner as Sample 11 except for the above.

[0098] (2) Evaluation

[0099] The following measurements and tests were performed on Samples 1 to 5 and Samples 11 to 16. The results are shown in Table 1.

[0100] (2.1) Determination of the amount of oil adhering to the center bare wire

[0101] Cut 80m of insulated wire into specified lengths, remove the coating with a special tool and pull out the conductor. Twist and remove the concentric bare wires in the opposite direction of the twisting direction, and pull out the center bare wire. This operation is carried out inside a constant temperature and humidity chamber at 25°C and 20% humidity. Then, measure the mass of the pulled-out center bare wire. Then, put the center bare wire and the extraction solvent (trimer of chlorotrifluoroethylene) in a glass-stoppered Erlenmeyer flask with cleaned oil, cover with a glass stopper, and stir evenly. Transfer the solution from which the oil attached to the center bare wire is extracted to a volumetric flask, further add the extraction solvent to the Erlenmeyer flask with a stopper, stir again, and transfer the solution from which the oil is extracted to a volumetric flask. Repeat these operations 3 times and dilute to the scale. Use an oil concentration meter (OCMA-555H manufactured by Horiba, Ltd.) to measure the mass of the oil dissolved in the extraction solvent. Then, divide by the mass of the center bare wire to determine the residual oil.

[0102] (2.2) Determination of elongation and conductor strength

[0103] The elongation and conductor strength of each insulated wire were measured using a universal testing machine (Autograph) manufactured by Shimadzu Corporation. As a result of the measurement, the elongation was 10% and the conductor strength was 402 MPa for all samples (not shown in the table).

[0104] (2.3) Determination of electrical conductivity

[0105] The conductivity of each insulated wire was calculated from the resistance value according to JIS H 0505. The resistance value was measured by a double bridge method using a conductor of 500 mm in length. As a result of the measurement and calculation, the conductivity of all samples was 81% IACS (not shown in the table).

[0106] (2.4) Determination of adhesion strength of coating layer

[0107] The adhesion strength of the coating is measured according to JASO D618. Specifically, an insulated wire of 100 mm in length is prepared, and the coating at one end thereof is removed to expose a portion of the conductor of 25 mm in length, and at the same time, a portion of the conductor of 25 mm in length at the other end is cut off and discarded. The insulated wire of 75 mm in total length is used as the measurement object, and the exposed conductor is inserted into the through hole of the retaining plate (a hole with a diameter larger than the outer diameter of the conductor and smaller than the outer diameter of the insulated wire). The retaining plate is fixed and one end of the conductor protruding from the retaining plate is stretched. Then, the minimum load when the coating is peeled off from the conductor and the conductor falls off is taken as the adhesion strength.

[0108] (2.5) Free fall test

[0109] A terminal was installed at one end of each insulated wire 300 mm long, and a 400 g weight was added to the front end of the terminal to apply a load to the wire barrel and the insulating barrel of the terminal. Then, the end of the side without the terminal was fixed at a height of 1000 mm. Then, the weight was allowed to fall freely from the height of 1000 mm, and visual inspection was performed to confirm whether the insulated wire was broken. The evaluation was carried out according to the following criteria.

[0110] Pass: No breakage of the insulated wire

[0111] Failure: Insulated wire is broken

[0112] (2.6) Coating removal test

[0113] The coating layer at one end of each insulated wire was removed using a dedicated tool (full-automatic wire cutting and stripping machine manufactured by Kodera Electronics Manufacturing Co., Ltd.) to confirm whether the coating layer could be removed. Evaluation was performed based on the following criteria.

[0114] Pass: When the coating is removed with the specified pulling force, no resin residue of the coating is found

[0115] Unacceptable: When the coating is removed with the specified pulling force, part of the coating (resin) remains attached.

[0116] Table 1

[0117]

[0118]

[0119] As shown in Table 1, using Samples 2 to 4 and Samples 13 to 15, excellent results were obtained in both the free fall test and the coating removal test.

[0120] Specifically, when the conductor twist pitch is 5 to 10 mm, the result of the free fall test is good (samples 2 to 4 and samples 13 to 15). In contrast, when the conductor twist pitch exceeds 10 mm, the result of the free fall test is unqualified (sample 1 and samples 11 and 12). If the twist pitch is less than 5 mm, the coating cannot be completely removed.

[0121] It is inferred from this that in order to provide an insulated wire that can withstand instantaneous stress and is not prone to breakage, it is useful to comprehensively consider the conductor's twist pitch, the amount of oil in the center bare wire, the material of the coating, the thickness of the coating, etc., and control them at a constant level.

[0122] Industrial Applicability

[0123] The present invention relates to an insulated wire having a conductor formed by twisting a plurality of bare wires and a coating layer covering the conductor, and is useful as a power line or a signal line for automobiles or industrial machinery.

[0124] Description of Reference Numerals

[0125] 1Insulated wire

[0126] 2 conductors

[0127] 2a Center bare wire

[0128] 2b concentric bare wire

[0129] 3. Coating layer

[0130] 10 terminals

[0131] 11 Chimeric part

[0132] 12 bobbin section

[0133] 13 Insulation tube

Claims

1. An insulated wire comprising a conductor formed by twisting a plurality of bare wires and a coating layer covering the conductor, in, The bare wire is composed of a copper alloy containing one or more additional elements selected from the group consisting of Mg, Sn and Si, and the remainder of the alloy consisting of Cu and inevitable elements. The amount of the added element in the copper alloy is 0.2 to 0.4% by mass. The conductor is composed of a central bare wire and a plurality of concentric bare wires arranged concentrically around the central bare wire. The amount of oil adhering to the central bare wire is 6 μg / g or less relative to the mass of the central bare wire. The conductor has a twist pitch of 5 to 10 mm and a cross-sectional area of ​​0.15 mm 2 the following, The coating layer is made of polyvinyl chloride resin. The coating layer has a thickness of 0.15 to 0.25 mm.

2. An insulated wire, It is characterized in that In the insulated wire of claim 1, When the conductor is a non-compressed conductor, the adhesion strength between the conductor and the coating layer is 19 to 23 N. When the conductor is a compressed conductor having a compression rate of 3 to 4%, the adhesion strength between the conductor and the coating layer is 20 to 21N.

3. An insulated wire with a terminal, comprising: The insulated wire according to claim 1 or 2; and A terminal is connected to an end of the insulated wire.

4. A method for manufacturing an insulated wire, wherein include: The process of preparing conductors by twisting multiple bare wires together; The conductor is subjected to a step of degreasing; The process of subjecting the conductor to tempering; as well as The step of coating the conductor with a resin to form a coating layer, In the conductor preparation step, a plurality of bare wires are made of copper alloy, one of the plurality of bare wires is used as a central bare wire, a plurality of concentric bare wires are arranged concentrically around the central bare wire, and the bare wires are twisted at a twist pitch of 5 to 10 mm to produce a conductor with a cross-sectional area of ​​0.15 mm 2 The conductor described below, wherein the copper alloy is an alloy containing one or more additive elements selected from the group consisting of Mg, Sn and Si, and the remainder is composed of Cu and inevitable elements, and the amount of the additive elements is 0.2 to 0.4% by mass. In the step of degreasing the conductor, the amount of oil adhering to the central bare wire is controlled to be less than 6 μg / g relative to the mass of the central bare wire. In the step of tempering the conductor, the conductor is heated at 250 to 350° C. for 2 to 10 hours. In the step of forming the coating layer, the conductor is coated with a polyvinyl chloride resin to form the coating layer having a thickness of 0.15 to 0.25 mm.

5. A method for manufacturing an electric wire with a terminal, wherein include: a step of peeling off the coating layer from an end portion of the insulated wire manufactured by the method for manufacturing an insulated wire according to claim 4 to expose the conductor; as well as A step of connecting a terminal to the exposed portion of the conductor.

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