JPH01198457A - Annealed copper wire for coil - Google Patents

Abstract

PURPOSE:To provide superior characteristics of ductility, softness, and freedom from rough surface by regulating the grain-size distribution in the crystalline structure of an annealed copper wire so that crystalline grains are large in the central part and small in the outside peripheral part. CONSTITUTION:An oxygen-free copper wire is coated with copper by means of hot dipping, which is wiredrawn and annealed in an Ar atmosphere, etc., so as to be formed into an annealed copper wire in which crystalline grains in a cross section are large in the central part and small in the outside peripheral part. This annealed copper wire is free from surface roughness and reduced in work hardening due to bending deformation. Accordingly, this wire can be most suitably used for annealed copper wire for coil which is coated with insulating film and used for motor, transformer, relay, etc.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is applicable to motors, transformers,
This relates to annealed copper wire for coil winding used in relays and the like.

[Conventional technology]

It is important for coil winding to be flexible, soft and easy to wind, not to break during winding, and not to lose its shape due to springback after winding. The ideal annealed copper wire for wiring has low yield strength and high tensile strength and elongation. Furthermore, as a characteristic representative of windability, it is generally said that a wire with a large spring elongation number (S, E, N) is good.

In order to obtain such a mild steel wire, various methods have been used in the past. The main ones are: (1) removing impurities in Cu, lowering the recrystallization temperature, and reducing lattice strain; reduce

(2) Increase the final annealing temperature or lengthen the annealing time to reduce dislocations that have multiplied during wire drawing.

(3) Repeated intermediate annealing is performed to prevent the formation of recrystallized texture.

etc.

(Problems to be Solved by the Invention) However, all of the above methods have advantages and disadvantages. In other words, the method (1) above requires special refining and melting and casting, which increases the cost, while the method (2) above has the advantage of being easy to manufacture, but it causes crystal growth to proceed at the same time as the dislocation density is reduced. There is a problem in that the crystals become coarse and the skin becomes noticeably rough. In addition, method (3) above shows excellent properties such as low yield strength and high tensile strength and elongation immediately after annealing, but because it is easy to work harden, the application and baking of the insulating film is difficult and the winding onto the bobbin is difficult. There is a problem in that the bending and tension that occur during this process make the finished product hard.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention has developed an annealed copper wire for coil winding that has no rough skin, is flexible, and is soft. It is characterized by having a recrystallized structure having a grain size distribution in which crystal grains are large in the center and small in the outer periphery.

(Function) That is, the annealed copper wire for coil winding of the present invention has a crystal structure that is
As shown in the figure, it has a recrystallized structure with a grain size distribution in which the crystal grains are large in the center and small in the outer periphery.Since the crystal grains in the outer periphery are relatively small, there is no need to worry about rough skin. In the center, the dislocation density is sufficiently reduced and the crystal grains are large, so the material exhibits supple and soft characteristics as a whole.

(Example) Diameter 5.0. Oxygen-free copper wire with an oxygen content of 3 ppm,
40 pl of oxygen by melt plating
The wire was coated with copper containing pI)m to obtain a pure copper wire with a diameter of 8.0#. This was made into a wire rod with a diameter of 2.6 m using a high-speed continuous wire drawing machine, and further drawn down to a diameter of 0.8 m using a continuous wire drawing machine without performing intermediate annealing. This was annealed at 400'C for 1 hour in an Ar atmosphere to produce an annealed copper wire of the present invention in which the cross-sectional structure was large at the center and small at the outer periphery, as shown in FIG.

On the other hand, for comparison, the oxygen-free copper wire with a diameter of 5.0 mm was drawn to a diameter of 2.6 m, half of which was subjected to intermediate annealing by electrical heating, and then drawn to a diameter of 0.8 m. A portion was annealed at 300°C for 1 hour in an Ar atmosphere,
The remaining wire was annealed at 400° C. for 1 hour in an Ar atmosphere to produce a comparative annealed copper wire with a small cross-sectional structure in both the center and the outer periphery, and a comparative annealed copper wire with a large cross-sectional structure in both the center and the outer periphery. Also, the remaining half has a diameter of 0.8 without intermediate annealing.
．． By drawing the wire to 300°C, annealing a part of it in an Ar atmosphere at 300°C for 1 hour, and annealing the remaining part in an Ar atmosphere at 400°C for 1 hour, the cross-sectional structure is small in both the center and the outer periphery. An annealed copper wire and a comparative annealed copper wire that were larger in both the center and the outer periphery were fabricated.

The tensile strength, 0.2% proof stress, elongation, and 0.2% proof stress after 20 bends were examined for the annealed copper wire of the present invention and the comparative annealed copper wire thus produced. The results are shown in Table 1. The 0.2% yield strength after 20 bends is as shown in Figure 2. Annealed copper wire (1) is attached to a urethane-covered sheave (2) with a diameter of 180 m.
With 2 kg weights (3) attached to both ends to apply tension, the annealed copper wire (1) was moved up and down along the circumferential surface of the urethane-covered sheave (2) and bent 20 times. The 0.2% yield strength of Ta-shun was measured.

As can be seen from Table 1, the present invention product NQ1 has large crystal grains at the center and small crystal grains at the outer periphery.
There is no problem of rough skin, and there is little work hardening due to bending deformation, making it ideal for coil winding. When coils were actually wound, almost no deformation due to springback was observed.

On the other hand, intermediate annealing was performed with a diameter of 2.6 m, and the final annealing temperature was 300 m.
The comparative amount Nα2, which is expressed as °C, has small crystals due to the low annealing temperature, and although there is no surface roughness, work hardening is severe. Diameter 2.
In the comparative amount Nα3, which was intermediately annealed at 6 m and the final annealing temperature was 400° C., the crystals became coarse and the surface became rough. In addition, with a diameter of 2.6 shoes, no intermediate annealing was performed, and the final annealing temperature was 300℃.
The comparative amount Nα4 has a large 0.2% yield strength after annealing due to the growth of the recrystallized texture, has a physically hard feel, has a diameter of 2.6M, does not undergo intermediate annealing, and has a final annealing temperature of 400 The comparative amount NQ5, which was set at .degree. C., had coarse crystals and rough skin, similar to the comparative amount N.alpha.3.

In this way, the comparative amount of conventional annealed copper wire has coarse crystals and rough surface, high 0.2% yield strength, or severe work hardening, resulting in high 0.2% yield strength after 20 bends. However, the product of the present invention, which is the annealed copper wire of the present invention, has the characteristics of no roughening, low 0.2% yield strength, and little work hardening, and is ideal as an annealed copper wire for coil winding. It is.

(Effects of the Invention) The annealed copper wire of the present invention has large crystal grains in the center and small crystal grains in the outer periphery, and has excellent properties such as being supple, soft, and free from rough skin, and is suitable as an annealed copper wire for coil winding. It has significant industrial effects, such as facilitating the production of coils for motors, transformers, relays, etc.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional structure diagram showing the annealed copper wire of the present invention, and Fig. 2 is a 20
This is an explanatory diagram of the bending method for measuring 0.2% yield strength after bending twice. 1. Annealed copper wire 2. Urethane pasting sheet 7 3. Weight

Claims (1)

[Claims] (1) In an annealed copper wire for coil winding that is coated with an insulating film around the periphery, the crystal structure of the annealed copper wire is a recrystallized structure in which the crystal grains are large in the center and the crystal grains are small in the outer periphery. Annealed copper wire for coil winding.