Copper alloy wire, copper alloy twisted wire, coated electric wire, and electric wire having terminal

Abstract

Provided is a copper alloy wire having: a composition comprising a copper alloy containing 0.05-1.60 mass % of iron, 0.01-0.70 mass % of phosphorus, and 0.05-0.70 mass % of tin; a wire diameter of 0.1-15.0 mm; and a cross section that has a central part and an outer peripheral part, wherein the ratio of the Vickers hardness of the central part to the Vickers hardness of the outer peripheral part is 1.2 or less.

Description

Copper alloy wires, copper alloy stranded wires, insulated wires, and wires with terminals

[0001] This disclosure relates to copper alloy wires, copper alloy stranded wires, insulated wires, and wires with terminals.

[0002] Patent Document 1 discloses a copper alloy wire made of a copper alloy containing specific additive elements in predetermined proportions. The specific additive element is at least one selected from the group consisting of iron (Fe), titanium (Ti), tin (Sn), silver (Ag), magnesium (Mg), zinc (Zn), chromium (Cr), and phosphorus (P). This copper alloy wire is manufactured by drawing a cast wire made by continuous casting. Hereinafter, the copper alloy wire will simply be referred to as copper alloy wire.

[0003] Japanese Patent Publication No. 2015-203136

[0004] The copper alloy wire of this disclosure comprises a composition consisting of a copper alloy containing 0.05% to 1.60% by mass of iron, 0.01% to 0.70% by mass of phosphorus, and 0.05% to 0.70% by mass of tin, a wire diameter of 0.1 mm to 15.0 mm, and a cross-section having a central part and an outer periphery. The ratio of the Vickers hardness of the central part to the Vickers hardness of the outer periphery is 1.2 or less.

[0005] Figure 1 is a schematic diagram showing an example of a copper alloy wire according to the embodiment. Figure 2 is a cross-sectional view taken along line II-II of Figure 1. Figure 3 is a schematic diagram illustrating the casting structure angle of the cast wire during the manufacturing process of the copper alloy wire according to the embodiment. Figure 4 is a schematic perspective view showing a coated electric wire according to the embodiment. Figure 5 is a schematic side view showing the vicinity of the terminal portion of an electric wire with a terminal according to the embodiment.

[0006] [Problems this disclosure aims to solve] Cast wire rods made of copper alloys may have a structure in which additive elements are segregated at grain boundaries, or a structure in which compounds containing additive elements are unevenly distributed. When cast wire rods having the above structure are subjected to wire drawing, breakage due to the above structure is likely to occur. Copper alloy wires obtained by drawing cast wire rods that are prone to breakage tend to have inferior mechanical properties.

[0007] One of the objectives of this disclosure is to provide a copper alloy wire with excellent mechanical properties.

[0008] [Effects of this disclosure] The copper alloy wire of this disclosure has excellent mechanical properties.

[0009] [Description of Embodiments of the Disclosure] First, embodiments of the Disclosure will be listed and described.

[0010] (1) The copper alloy wire according to the embodiment of the present disclosure comprises a composition consisting of a copper alloy containing 0.05% by mass or more and 1.60% by mass or less of iron, 0.01% by mass or more and 0.70% by mass or less of phosphorus, and 0.05% by mass or more and 0.70% by mass or less of tin, a wire diameter of 0.1 mm or more and 15.0 mm or less, and a cross-section having a central part and an outer part. The ratio of the Vickers hardness of the central part to the Vickers hardness of the outer part is 1.2 or less.

[0011] Copper alloy wires made from copper alloys containing iron, phosphorus, and tin as additive elements within the above ranges exhibit excellent tensile strength. In particular, copper alloy wires with a ratio of Vickers hardness of the center to Vickers hardness of the outer circumference of 1.2 or less have excellent mechanical properties throughout their entire length because the center is not brittle. Hereinafter, the ratio of Vickers hardness of the center to Vickers hardness of the outer circumference will simply be referred to as the hardness ratio. Copper alloy wires with a hardness ratio of 1.2 or less are less prone to breakage during the manufacturing process and have excellent productivity. Copper alloy wires with a hardness ratio of 1.2 or less are manufactured by drawing cast wire rods with a hardness ratio of 1.2 or less. If the hardness ratio is greater than 1.2, the center of the cast wire rod is too hard compared to other parts, and that hard part is brittle. When cast wire rods with a hardness ratio greater than 1.2 are drawn, breakage is likely to occur starting from the hard part in the center. In other words, cast wire with a hardness ratio of 1.2 or less is resistant to breakage, and copper alloy wire obtained by drawing this resistant cast wire is not only highly productive but also possesses excellent mechanical properties.

[0012] (2) In the copper alloy wire described in (1) above, the central part is the interior of a circle with a radius of 1 / 8 of the wire diameter, centered on the central axis of the copper alloy wire, and the outer part may be the interior of a ring shape with a predetermined length of 1 / 8 of the wire diameter extending from the outer surface of the copper alloy wire toward the central axis.

[0013] Copper alloy wires with a hardness ratio of 1.2 or less in a relatively narrow central area tend to have high mechanical properties along their entire length.

[0014] (3) In the copper alloy wire described in (1) or (2) above, the outer surface of the copper alloy wire may have processing marks.

[0015] The presence of processing marks on the outer surface of the copper alloy wire indicates that it is a copper alloy wire obtained by applying a corresponding processing to a cast wire. The processing marks are, for example, wire drawing marks. As mentioned above, copper alloy wire with a hardness ratio of 1.2 or less is manufactured by applying wire drawing to a cast wire with a hardness ratio of 1.2 or less. Copper alloy wire obtained by applying wire drawing to a cast wire with a hardness ratio of 1.2 or less has excellent productivity and excellent mechanical properties.

[0016] (4) In any of the copper alloy wires described in (1) to (3) above, the tensile strength may be 250 MPa or more.

[0017] Copper alloy wires with a tensile strength of 250 MPa or more have excellent strength.

[0018] (5) The copper alloy stranded wire according to the embodiment of the present disclosure is made by twisting together a plurality of copper alloy wires according to any of (1) to (4) above.

[0019] Stranded wire exhibits superior flexibility compared to single wire with the same cross-sectional area, and each strand is less likely to break even when subjected to impact and repeated bending. Therefore, the above-mentioned copper alloy stranded wire has excellent impact resistance and fatigue properties.

[0020] (6) An insulated wire according to an embodiment of the present disclosure comprises a conductor and an insulating layer covering the outer circumference of the conductor, wherein the conductor comprises the copper alloy stranded wire described in (5) above.

[0021] The above-mentioned insulated wire has a conductor made of copper alloy stranded wire, which has excellent impact resistance and fatigue characteristics, and therefore has excellent impact resistance and fatigue characteristics.

[0022] (7) The wire with a terminal according to the embodiment of the present disclosure comprises the insulated wire described in (6) above and a terminal portion attached to the end of the insulated wire.

[0023] The above-mentioned wire with terminals is composed of a coated wire that has excellent impact resistance and fatigue characteristics, and therefore has excellent impact resistance and fatigue characteristics.

[0024] [Details of Embodiments of the Disclosure] Specific examples of copper alloy wires, copper alloy stranded wires, insulated wires, and terminal wires of the Disclosure will be described with reference to the drawings. Identical reference numerals in the drawings indicate the same or corresponding parts. In each drawing, some parts of the configuration may be exaggerated or simplified for illustrative purposes. The dimensional ratios of parts in the drawings may also differ from those of the actual components. The present invention is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be included.

[0025] <Copper Alloy Wire> <Overview> The copper alloy wire 1 of this embodiment has a composition consisting of a copper alloy containing specific additive elements in predetermined proportions, a wire diameter 1d as shown in Figure 1, and a cross-section 2 as shown in Figure 2. The cross-section 2 comprises a central part 3 and an outer peripheral part 4. One of the features of the copper alloy wire 1 of this embodiment is that its hardness ratio is 1.2 or less. The hardness ratio is the ratio of the Vickers hardness of the central part 3 to the Vickers hardness of the outer peripheral part 4. The copper alloy wire 1 is manufactured by drawing a cast wire.

[0026] ≪Composition≫ The composition of copper alloy wire 1 is a copper alloy containing additive elements, with the remainder being copper (Cu) and unavoidable impurities. Copper alloys are alloys that contain the most copper. The additive elements include iron (Fe), phosphorus (P), and tin (Sn) as essential additive elements. The iron content is 0.05% by mass or more and 1.60% by mass or less. The phosphorus content is 0.01% by mass or more and 0.70% by mass or less. The tin content is 0.05% by mass or more and 0.70% by mass or less. Copper alloy wire 1, which is made of a copper alloy containing iron, phosphorus, and tin as additive elements within the above ranges, has excellent tensile strength. The content of each element in the composition is the mass percentage of each element when the composition of the copper alloy is set to 100% by mass.

[0027] The iron content may be 0.10% by mass or more and 1.50% by mass or less, or 0.20% by mass or more and 1.40% by mass or less. The phosphorus content may be 0.03% by mass or more and 0.60% by mass or less, or 0.05% by mass or more and 0.50% by mass or less. The tin content may be 0.07% by mass or more and 0.60% by mass or less, or 0.10% by mass or more and 0.50% by mass or less.

[0028] The composition of copper alloy wire 1 may or may not include additive elements other than iron, phosphorus, and tin. Examples of optional additive elements other than iron, phosphorus, and tin include silver (Ag), magnesium (Mg), nickel (Ni), and silicon (Si). There may be one or more optional additive elements other than iron, phosphorus, and tin. In other words, the composition of copper alloy wire 1 may include essential additive elements and at least one of the optional additive elements, with the remainder consisting of unavoidable impurities and copper.

[0029] The total content of additive elements, including both essential and optional additive elements, is, for example, 0.11% by mass or more and 3.10% by mass or less, 0.12% by mass or more and 3.00% by mass or less, or 0.13% by mass or more and 2.90% by mass or less.

[0030] ≪Wire Diameter≫ The wire diameter 1d of copper alloy wire 1 is 0.1 mm or more and 15.0 mm or less. If the wire diameter 1d is 0.1 mm or more, the degree of wire drawing in the manufacturing process of copper alloy wire 1 can be increased. A greater degree of wire drawing tends to increase the strength of the copper alloy wire 1 produced by work hardening. If the wire diameter 1d is 15.0 mm or less, the casting speed in the manufacturing process of copper alloy wire 1 can be increased. A faster casting speed allows for more productive production of copper alloy wire 1. The casting speed will be discussed later. The wire diameter 1d of copper alloy wire 1 may also be 0.11 mm or more and 14.0 mm or less, or 0.12 mm or more and 13.0 mm or less. The wire diameter 1d of copper alloy wire 1 may also be 0.1 mm or more and 3.0 mm or less, or 0.1 mm or more and 2.5 mm or less.

[0031] The shape of the cross-section 2 of the copper alloy wire 1 is not particularly limited. The cross-section 2 is a section perpendicular to the longitudinal direction of the copper alloy wire 1. As shown in FIG. 2, the shape of the cross-section 2 in this example is circular. The copper alloy wire 1 in this example is a round wire as shown in FIG. 1. The shape of the cross-section 2 may be an elliptical shape or a polygonal shape. The polygonal shape is, for example, a square shape or a hexagonal shape. When the copper alloy wire 1 is a round wire, the shape of the cross-section 2 is circular, and the wire diameter 1d of the copper alloy wire 1 is the diameter. When the shape of the cross-section 2 is an elliptical shape or a polygonal shape, the wire diameter 1d is the diameter of a circle having the same area as the area of the cross-section 2.

[0032] <<Center portion and outer peripheral portion>> As shown in FIG. 2, the cross-section 2 includes a center portion 3 and an outer peripheral portion 4. The center portion 3 is inside a circle centered on the central axis of the copper alloy wire 1 and having a radius 3r of 1 / 8 of the wire diameter 1d. The outer peripheral portion 4 is a ring-shaped interior extending from the outer peripheral surface 5 of the copper alloy wire 1 toward the central axis with a predetermined length 3L of 1 / 8 of the wire diameter 1d. The portion between the center portion 3 and the outer peripheral portion 4 is an intermediate portion 6. The intermediate portion 6 is a ring-shaped interior between the outer peripheral surface of the center portion 3 and the inner peripheral surface of the outer peripheral portion 4. In FIG. 2, for clarity, the boundaries between the center portion 3 and the intermediate portion 6 and between the outer peripheral portion 4 and the intermediate portion 6 are indicated by a two-dot chain line.

[0033] The ratio of the Vickers hardness of the center portion 3 to the Vickers hardness of the outer peripheral portion 4 is 1.2 or less. The copper alloy wire 1 having a hardness ratio of 1.2 or less has excellent mechanical properties over the entire length of the copper alloy wire 1 because the center portion 3 is not embrittled. The copper alloy wire 1 having a hardness ratio of 1.2 or less is manufactured without wire breakage occurring during the manufacturing process as shown in the test examples described later. The copper alloy wire 1 having a hardness ratio of 1.2 or less is manufactured by performing wire drawing on a cast wire rod having a hardness ratio of 1.2 or less. When the hardness ratio exceeds 1.2, the center portion of the cast wire rod is too hard compared to other portions, and the hard portion is embrittled. When wire drawing is performed on a cast wire rod having a hardness ratio exceeding 1.2, wire breakage is likely to occur starting from the hard portion in the center. In other words, since no wire breakage occurred when wire drawing was performed on a cast wire rod having a hardness ratio of 1.2 or less, the copper alloy wire 1 having a hardness ratio of 1.2 or less is obtained. The hardness ratio may be 1.1 or less, 1.0 or less, 0.9 or less, or 0.8 or less.

[0034] The ratio of the Vickers hardness of the intermediate portion 6 to the Vickers hardness of the outer peripheral portion 4 is, for example, 1.2 or less. Also, the ratio of the Vickers hardness of the central portion 3 to the Vickers hardness of the intermediate portion 6 is, for example, 1.2 or less. That is, in the copper alloy wire 1 of this example, the variation in Vickers hardness is small over the entire cross section 2.

[0035] The Vickers hardness of each of the central portion 3, the outer peripheral portion 4, and the intermediate portion 6 can be measured based on JIS Z 2244:2009. The Vickers hardness can be measured by pressing a measuring indenter against each of the central portion 3, the outer peripheral portion 4, and the intermediate portion 6 in the cross section 2. The Vickers hardness of the outer peripheral portion 4 may be measured by pressing the measuring indenter against the outer peripheral surface 5 of the copper alloy wire 1. The Vickers hardness of the central portion 3 is the average value obtained by taking five or more different cross sections 2 in the same copper alloy wire 1 and measuring one location including the central axis of the copper alloy wire 1 in each cross section 2. The Vickers hardness of each of the outer peripheral portion 4 and the intermediate portion 6 is the average value obtained by measuring four locations that divide the entire circumference into four equal parts around the central axis of the copper alloy wire 1.

[0036] The outer peripheral surface 5 of the copper alloy wire 1 has, for example, processing marks (not shown). By the fact that processing marks are formed on the outer peripheral surface 5 of the copper alloy wire 1, it can be understood that the copper alloy wire 1 is obtained by subjecting a cast wire rod to processing corresponding to the processing marks. The processing marks are, for example, wire drawing processing marks. The wire drawing processing marks extend along the longitudinal direction of the copper alloy wire 1 and are formed in a streak shape. The copper alloy wire 1 is manufactured by subjecting a cast wire rod to wire drawing processing. The copper alloy wire 1 may also be manufactured by subjecting a wire rod obtained by subjecting a cast wire rod to rolling processing to wire drawing processing.

[0037] <<Tensile Strength>> The tensile strength of the copper alloy wire 1 is, for example, 250 MPa or more. The copper alloy wire 1 having a tensile strength of 250 MPa or more is excellent in strength. The tensile strength can be measured based on JIS Z 2241:2011. The tensile strength may be 260 MPa or more, or 270 MPa or more. The tensile strength may be 1200 MPa or less from the viewpoint of balance with conductivity.

[0038] <<Elongation>> The copper alloy wire 1 having a hardness ratio of 1.2 or less has, for example, an elongation 10% or more higher than that of the copper alloy wire 1 having a hardness ratio exceeding 1.2.

[0039] <Method for Manufacturing Copper Alloy Wire> The copper alloy wire 1 described above can be manufactured through a casting process to produce a cast wire made of copper alloy, and a wire drawing process to draw the cast wire. Figure 3 shows an example of a cast wire 10.

[0040] ≪Casting Process≫ In the casting process, cast wire 10 is produced by intermittent continuous casting of molten copper alloy. The copper alloy has the same composition as the copper alloy wire 1 described above. Continuous casting can be, for example, top-draw casting, vertical casting, or horizontal casting. In top-draw casting, the end of a cylindrical mold is placed inside the molten metal, and the solidified wire inside the mold is pulled upwards towards the top of the mold to produce the cast wire 10. Intermittent continuous casting is a method in which the casting wire 10 is repeatedly drawn out and stopped.

[0041] The ratio S1 / ST of the time for one draw S1 (sec) to the total time ST of one stop S2 (sec) is, for example, 0.70 or less. The wire diameter x (mm) of the cast wire 10 and the casting speed y (mm / sec) of the cast wire 10 satisfy, for example, y ≤ 155 / x. The casting speed y is the value obtained by dividing the length of one cast wire 10 produced by the time required to produce one cast wire 10. That is, the casting speed y is the value obtained by dividing the length of the cast wire 10 by the total time of all draw S1 and all stop S2. By having a ratio S1 / ST of 0.70 or less and satisfying y ≤ 155 / x, it is easy to produce a cast wire 10 with a cast structure angle of 70° or less, as described later. A cast wire 10 with a cast structure angle of 70° or less is likely to satisfy a hardness ratio of 1.2 or less.

[0042] The ratio S1 / ST may be 0.65 or less, or may be 0.60 or less. The lower limit of the ratio S1 / ST is not particularly limited. The ratio S1 / ST may be 0.10 or more, 0.15 or more, or 0.20 or more. That is, the ratio S1 / ST may be 0.10 or more and 0.70 or less, 0.15 or more and 0.65 or less, or 0.20 or more and 0.60 or less. The wire diameter x is, for example, 5 mm or more and 25 mm or less. The wire diameter x may be 6 mm or more and 24 mm or less, or 7 mm or more and 23 mm or less. The casting speed y is, for example, 1.67 mm / sec or more and 30 mm / sec or less. The casting speed y may be 2 mm / sec or more and 28 mm / sec or less, or 2.5 mm / sec or more and 25 mm / sec or less.

[0043] The acceleration from the stopped state of the cast wire 10 until the pulling speed is reached is, for example, 50 mm / sec ２ or more and 7000 mm / sec ２ or less. The pulling speed is the value obtained by dividing the length of the cast wire 10 by the total time of all pulling times S1. When the acceleration is 50 mm / sec ２ or more and 7000 mm / sec ２ or less, it is easy to manufacture the cast wire 10 having a casting structure angle of 70° or less described later. The cast wire 10 having a casting structure angle of 70° or less easily satisfies a hardness ratio of 1.2 or less. The acceleration is 100 mm / sec ２ or more and 6000 mm / sec ２ or less, or 150 mm / sec ２ or more and 5000 mm / sec ２ or less may also be used.

[0044] The deceleration from the above pulling speed until the cast wire 10 stops is, for example, 100 mm / sec ２ or more. When the deceleration is 100 mm / sec ２ or more, it is easy to manufacture the cast wire 10 having a casting structure angle of 70° or less described later. The cast wire 10 having a casting structure angle of 70° or less easily satisfies a hardness ratio of 1.2 or less. The deceleration is 150 mm / sec ２ or more, or 200 mm / sec ２ or more may also be used. The deceleration is, for example, 1000 mm / sec ２ or less, 800 mm / sec２ The following, or 600 mm / sec ２ The following applies: That is, the deceleration is 100 mm / sec. ２ 1000mm / sec or more ２ Below, 150mm / sec ２ 800mm / sec or more ２ The following, or 200 mm / sec ２ 600mm / sec or more ２ The following is also acceptable.

[0045] In the casting process, the ratio S1 / ST and deceleration are kept constant within the above range, and the acceleration is 50 mm / sec. ２ More than 7000mm / sec ２ By repeatedly drawing out and stopping the cast wire in the following manner, it is easier to satisfy a hardness ratio of 1.2 or less.

[0046] The casting structure angle is determined as follows: A longitudinal section of the cast wire 10 is taken as shown in Figure 3. The longitudinal section is a cross-section that passes through the center of the cast wire 10 and is along the axis of the cast wire 10. The longitudinal section is taken such that the length between the upper edge 21 and the lower edge 22 of the longitudinal section is equal to the wire diameter x. In the longitudinal section of Figure 3, the direction of the white arrow going from left to right on the page is the direction of propagation of the cast wire 10.

[0047] An upper parallel line 31 is drawn parallel to the upper side 21, passing through a point 1 / 4 times the line diameter x from the upper side 21 towards the lower side 22 of the vertical section. Five upper reference points 51 are drawn at 6 mm intervals along the upper parallel line 31, from the left side 23 towards the right side 24. A lower parallel line 32 is drawn parallel to the lower side 22, passing through a point 1 / 4 times the line diameter x from the lower side 22 towards the upper side 21 of the vertical section. Five lower reference points 52 are drawn at 6 mm intervals along the lower parallel line 32, from the left side 23 towards the right side 24. The five upper reference points 51 are designated as the 1st to 5th upper reference points 51, in order from left to right. The five lower reference points 52 are designated as the 1st to 5th lower reference points 52, in order from left to right.

[0048] An upper crossing line 41 is formed that follows the grain boundary and intersects the upper parallel line 31. A lower crossing line 42 is formed that follows the grain boundary and intersects the lower parallel line 32. In any of the continuous casting methods described above, the grain boundaries are formed such that they are inclined from the axis of the cast wire 10 toward the upper edge 21 or lower edge 22 as the cast wire 10 moves toward the direction of travel. This is because the cast wire 10 is manufactured by cooling the molten metal in contact with the mold sequentially from the outer surface toward the center and sequentially from the front toward the back in the direction of travel of the molten metal. The upper crossing lines 41 and lower crossing lines 42 are lines that are inclined toward the upper edge 21 or lower edge 22 as the cast wire 10 moves toward the direction of travel, as shown in Figure 3. In Figure 3, for the sake of explanation, seven upper crossing lines 41 and six lower crossing lines 42 are shown. The seven upper crossing lines 41 are designated as the first to seventh upper crossing lines 41, from left to right. The six lower crossing lines 42 are designated as the 1st to 6th lower crossing lines 42, in order from left to right.

[0049] On the upper parallel lines 31, find the smaller angle θ between each of the upper crossing lines 41 that is closest to each of the first to fifth upper reference points 51 and the upper parallel lines 31. That is, in Figure 3, find the smaller angle θ between each of the second upper crossing line 41, the fourth upper crossing line 41, the fifth upper crossing line 41, the sixth upper crossing line 41, and the seventh upper crossing line 41 and the upper parallel lines 31. On the lower parallel lines 32, find the smaller angle θ between each of the lower crossing lines 42 that is closest to each of the first to fifth lower reference points 52 and the lower parallel lines 32. That is, in Figure 3, find the smaller angle θ between each of the second lower crossing line 42, the third lower crossing line 42, the fourth lower crossing line 42, the fifth lower crossing line 42, and the sixth lower crossing line 42 and the lower parallel lines 32. The average of the ten angles θ obtained is the casting microstructure angle.

[0050] In Figure 3, for the sake of explanation, an example is shown in which there is no upper crossing line 41 passing through the upper reference point 51. However, if there is an upper crossing line 41 passing through the upper reference point 51, then the upper crossing line 41 passing through the upper reference point 51 is the upper crossing line 41 that is closest to the upper reference point 51. The same applies to the lower crossing line 42, which is closest to the lower reference point 52. In Figure 3, near the second upper reference point 51, there is a third upper crossing line 41 located to the left of the second upper reference point 51 and a fourth upper crossing line 41 located to the right. Here, on the upper parallel line 31, the distance between the second upper reference point 51 and the fourth upper crossing line 41 is shorter than the distance between the second upper reference point 51 and the third upper crossing line 41. Therefore, we find the smaller of the angles θ between the fourth upper intersecting line 41 and the upper parallel line 31, but we do not find the smaller of the angles θ between the third upper intersecting line 41 and the upper parallel line 31.

[0051] ≪Wire Drawing Process≫ In the wire drawing process, the cast wire rod 10 is subjected to wire drawing. The degree of wire drawing can be appropriately selected according to the wire diameter x of the cast wire rod 10 and the wire diameter 1d of the copper alloy wire 1 after wire drawing. The degree of wire drawing is, for example, 0.1 to 12.0, 0.2 to 11.0, or 0.3 to 10.0. The degree of wire drawing is the absolute value expressed as a natural logarithm of the ratio of the cross-sectional area of ​​the wire rod before drawing to the cross-sectional area of ​​the wire rod after drawing. Wire drawing is performed using, for example, a die conforming to the AWG (American Wire Gauge) standard.

[0052] In the wire drawing process, the wire rod obtained by rolling the cast wire rod 10 may also be subjected to wire drawing.

[0053] Cast wire rods 10 with a hardness ratio of 1.2 or less are less prone to breakage during wire drawing. Therefore, copper alloy wires 1 obtained by drawing cast wire rods 10 with a hardness ratio of 1.2 or less are less prone to breakage during the manufacturing process and have excellent productivity.

[0054] <Copper Alloy Stranded Wire> The copper alloy wire 1 of the embodiment can be used as a strand in a copper alloy stranded wire 120, as shown in Figure 4. The copper alloy stranded wire 120 is made by twisting together multiple copper alloy wires 1. Compared to a single copper alloy wire 1 having the same cross-sectional area, the copper alloy stranded wire 120 has superior flexibility, and each strand is less likely to break even when subjected to impact and repeated bending. Therefore, the copper alloy stranded wire 120 has excellent impact resistance and fatigue properties. Figure 4 illustrates a copper alloy stranded wire 120 with seven concentric strands, but the number of strands of copper alloy wire 1 and the twisting method can be changed as appropriate.

[0055] The copper alloy stranded wire 120 can be a compressed stranded wire, which is formed by compression molding after twisting. Compressed stranded wire has excellent stability in the twisted state. Furthermore, compressed stranded wire tends to have better mechanical properties than simply twisted wire and can be made in a smaller diameter.

[0056] <Insulated Wire> The copper alloy wire 1 or the copper alloy stranded wire 120 of the embodiment can be used as a conductor for electric wires. The insulated wire 100 of the embodiment comprises a conductor 110 and an insulating layer 130, as shown in Figure 4. The conductor 110 comprises a copper alloy stranded wire 120. The insulating layer 130 covers the outer circumference of the conductor 110. The insulated wire 100 has excellent impact resistance and fatigue characteristics because it comprises a conductor 110 made of a copper alloy stranded wire 120 which has excellent impact resistance and fatigue characteristics. As an alternative example of the insulated wire 100, the conductor 110 may be a single-strand copper alloy wire 1.

[0057] The insulating material forming the insulating layer 130 can be appropriately selected. Examples of insulating materials include polyvinyl chloride (PVC), non-halogen resins, and materials with excellent flame retardancy. Known insulating materials can be used. The thickness of the insulating layer 130 can be appropriately selected within a range that provides a predetermined insulating strength.

[0058] <Wire with Terminal> The insulated wire 100 of this embodiment can be used as a wire for various applications, such as wire harnesses mounted on equipment such as automobiles or airplanes, wiring for various electrical equipment such as industrial robots, and wiring for buildings. When used in wire harnesses, typically a terminal portion 210 is attached to the end of the insulated wire 100. As shown in Figure 5, the wire with terminal 200 of this embodiment comprises the insulated wire 100 of this embodiment and a terminal portion 210 attached to the end of the insulated wire 100. This wire with terminal 200 has excellent impact resistance and fatigue characteristics because it is equipped with an insulated wire 100 which has excellent impact resistance and fatigue characteristics. In Figure 5, a crimp terminal is shown as the terminal portion 210, which has a female or male mating portion 212 at the first end, an insulation barrel portion 213 attached to the insulating layer 130 at the second end, and a wire barrel portion 211 attached to the conductor 110 in the middle. The crimp terminal is crimped to the end of the conductor 110, which is exposed at the end of the insulated wire 100 after the insulating layer 130 has been removed, thereby connecting the conductor 110 electrically and mechanically. In addition to crimp terminals and other crimp-type terminals, the terminal portion 210 may also be connected by melting the conductor 110.

[0059] [Test Example] A cast wire made of copper alloy was prepared, and the presence or absence of wire breakage was investigated when this cast wire was subjected to wire drawing.

[0060] <Samples> For all of the samples, from sample No. 1 to sample No. 3, sample No. 11, and sample No. 12, cast wire rods were produced by intermittent continuous casting of molten copper alloy, and these cast wire rods were then drawn to produce drawn wire rods.

[0061] In each sample, the molten copper alloy has a composition containing iron, phosphorus, and tin, with the remainder being copper and unavoidable impurities. The proportion of each element contained in the molten metal of each sample is as shown in the composition in Table 1. The cast wires of each sample were manufactured by intermittent top-draw continuous casting. The length of the cast wire was 50 m. The wire diameter (mm), casting speed (mm / sec), ratio of the time of one draw S1 (sec) to the total time ST of one draw S1 (sec) and one stop S2 (sec), and acceleration (mm / sec) from the stopped state to the draw speed of the cast wire are specified. ２ ), and the deceleration (mm / sec) from the above-mentioned drawing speed until the cast wire stops. ２ The results are as shown in Table 1. In this example, the ratio S1 / ST and deceleration were kept constant, while the acceleration was varied. For samples No. 1 to No. 3, the casting speed y and the wire diameter x of the cast wire satisfy y ≤ 155 / x.

[0062] Each drawn wire was manufactured by drawing the prepared cast wire. The degree of drawing and the final wire diameter (mm) of the manufactured drawn wire are shown in Table 2.

[0063]

[0064] <Casting Microstructure Angle> The casting microstructure angle (°) of the cast wire for each sample was determined. The method for determining the casting microstructure angle is as described above, referring to Figure 3. The results of the casting microstructure angle are shown in Table 1. The values ​​shown in Table 1 are rounded to the nearest tenth.

[0065] <Component Analysis> The composition of each drawn wire sample was investigated by mapping analysis using an electron beam microanalyzer (EPMA). As a result, the composition of each drawn wire sample was the same as the composition of the molten copper alloy. In other words, the composition of each drawn wire sample was as shown in Table 1.

[0066] <Hardness Ratio> For each drawn wire sample, the Vickers hardness of the center and outer periphery was measured according to JIS Z 2244:2009. The Vickers hardness of the center was the average value obtained by taking five or more different cross-sections from the same sample and measuring at one point in each cross-section that included the central axis of the copper alloy. The Vickers hardness of the outer periphery was the average value obtained by pressing a measuring indenter against four points on the outer surface of the drawn wire, dividing the entire circumference around the central axis of the drawn wire into four equal parts. The hardness ratio was calculated by determining the ratio of the Vickers hardness of the center to the Vickers hardness of the outer periphery. The results are shown in Table 2.

[0067] <Tensile Strength> The tensile strength of each drawn wire sample was measured according to JIS Z 2241:2011. Specifically, a sample of each material was prepared, and a tensile test was performed with a gripping distance of 200 mm and a tensile speed of 20 mm / min until the sample broke. The tensile strength was calculated by dividing the maximum load value during this tensile test by the area of ​​the cross-sectional surface of the sample. The results are shown in Table 2.

[0068] <Presence or absence of wire breakage during wire drawing> We investigated whether or not wire breakage occurred during the wire drawing process for each sample. The results are shown in Table 2. In the "No breakage" column of Table 2, "None" means that the drawn wire was manufactured without any wire breakage. "Yes" means that wire breakage occurred.

[0069]

[0070] No breakage occurred during the wire drawing process for samples No. 1 to No. 3. The hardness ratio of samples No. 1 to No. 3 was 1.2 or less. For the cast wires of samples No. 1 to No. 3, the cast structure angle was 70° or less, and it is thought that the hardness ratio was 1.2 or less. By performing wire drawing on cast wires with a hardness ratio of 1.2 or less, it was possible to perform wire drawing without breakage, and thus drawable wires with a hardness ratio of 1.2 or less were produced. All of the drawable wires from samples No. 1 to No. 3, which did not break during the wire drawing process, are thought to have excellent mechanical properties when used as drawable wires.

[0071] In the drawn wires of samples No. 11 and No. 12, wire breakage occurred during the wire drawing process. The hardness ratio of the drawn wires of samples No. 11 and No. 12 was greater than 1.2. In the cast wires of samples No. 11 and No. 12, the cast structure angle was greater than 70°, and it is thought that the hardness ratio was greater than 1.2. When the hardness ratio is greater than 1.2, the center of the cast wire is too hard compared to other parts, and that hard part becomes brittle. Therefore, it is thought that when cast wires with a cast structure angle greater than 70° and a hardness ratio greater than 1.2 were subjected to wire drawing, wire breakage occurred starting from that hard part.

[0072] 1 Copper alloy wire 2 Cross section 3 Center section 4 Outer section 5 Outer surface 6 Middle section 1d Wire diameter 3r Radius 3L Length 10 Cast wire 21 Top edge, 22 Bottom edge, 23 Left edge, 24 Right edge 31 Upper parallel lines, 32 Lower parallel lines 41 Upper crossing lines, 42 Lower crossing lines 51 Upper reference point, 52 Lower reference point x Wire diameter θ Angle 100 Insulated wire 110 Conductor, 120 Copper alloy stranded wire, 130 Insulation layer 200 Wire with terminal 210 Terminal section, 211 Wire barrel section 212 Fitting section, 213 Insulation barrel section

Claims

1. A copper alloy wire comprising: a composition consisting of a copper alloy containing 0.05% by mass or more and 1.60% by mass or less of iron, 0.01% by mass or more and 0.70% by mass or less of phosphorus, and 0.05% by mass or more and 0.70% by mass or less of tin; a wire diameter of 0.1 mm or more and 15.0 mm or less; and a cross-section having a central part and an outer part, wherein the ratio of the Vickers hardness of the central part to the Vickers hardness of the outer part is 1.2 or less.

2. The copper alloy wire according to claim 1, wherein the central part is the interior of a circle with a radius of 1 / 8 of the wire diameter, centered on the central axis of the copper alloy wire, and the outer part is the interior of a ring shape with a predetermined length of 1 / 8 of the wire diameter extending from the outer surface of the copper alloy wire toward the central axis.

3. The copper alloy wire according to claim 1 or claim 2, wherein the outer surface of the copper alloy wire has processing marks.

4. A copper alloy wire according to any one of claims 1 to 3, wherein the tensile strength is 250 MPa or more.

5. A copper alloy stranded wire comprising a plurality of copper alloy wires according to any one of claims 1 to 4, twisted together.

6. A covered electric wire comprising a conductor and an insulating layer covering the outer circumference of the conductor, wherein the conductor comprises the copper alloy stranded wire described in claim 5.

7. A wire with a terminal, comprising the insulated wire described in claim 6 and a terminal portion attached to the end of the insulated wire.

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