JPS63144849A - Method for controlling performance of unidirectionally solidified material - Google Patents

Abstract

PURPOSE:To obtain a cable stock which is free from dispersion in transmission characteristic from a unidirectionally solidified material to be cast by a unidirectional solidification method by controlling the tensile strength electrical coductivity of the unidirectionally solidified material by the solidifying speed at the time of casting. CONSTITUTION:A unidirectionally solidified ingot of oxygenfree copper is produced by, for example, a continuous casting method using a heated casting mold. Molten copper 4 in a casting furnace 3 is admitted into the casting mold 2 provided with a heating element 1 and the drawn-out ingot 6 is cooled with the water gushed from coolers 5 by which the molten metal 4 in contact with the ingot 6 is solidified in the casting mold 2. The solidified ingot is drawn by pinch rolls 7. The tensile strength and electrical coductivity of the ingot 6 having the unidirectionally solidified structure are controlled by the solidifying speed at the time casting. The tensile strength and electrical coductivity of the ingot 6 worked after the casting are controlled by the solidifying speed at the time of casting and the reduction ratio at the time of working. The cable stock having the excellent transmission characteristics is thereby obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling the performance of unidirectionally solidified materials, including single crystal materials cast by a unidirectional solidification method or processed after casting.
In particular, it has made it possible to control the tensile strength and electrical conductivity of unidirectionally solidified materials.

[Conventional technology]

Single-crystal materials and unidirectionally solidified materials, such as oxygen-free copper ingots with a unidirectionally solidified structure, have crystal grains grown in the casting direction, and are cast using a continuous casting method that uses a heated mold heated above the melting point of the cast metal. , selfless rotary casting using the Czochralski method, Bridgman method, etc. The ingots made by this casting method are then used after being made into fine wires by only cold working, and although the processing strain during processing remains in the fine wires, the unidirectional solidification structure of the ingot, which is the raw material, is It works effectively and exhibits excellent properties not found in conventional materials, especially as signal transmission cables for audio equipment and video equipment (hereinafter simply referred to as cables).

Furthermore, by reducing the amount of residual processing strain inside the thin wire used as the cable, or by making the cable free from processing distortion, it is possible to obtain a cable with even more sagging transmission characteristics.

In other words, in order to minimize processing strain, an ingot with a cross-sectional area slightly larger than that of conventional cables is cast, and a cable is made with slight processing, or wire drawing, etc., which causes processing distortion, is cast. It is possible to use the ingot as a cable without adding it at all. For example, a small-diameter ingot having the same cross-sectional area as a conventional cable may be manufactured, and a single wire or a plurality of wires may be twisted together to form a cable.

[Problem that the invention seeks to solve]

Small-diameter ingots that are not subjected to wire drawing or the like and cables that have been slightly strained have superior transmission characteristics compared to conventional cables, but they have the following problems.

Production of small-diameter ingots: when making a long small-diameter ingot obtained by continuous casting into a cable without applying processing strain, and when making a cable by applying a slight processing strain to a small-diameter ingot Tensile strength (Ng/i) and conductivity (%IA) between lots
C3), which has the disadvantage of causing variations in the transmission characteristics of the cable.

[Means for solving problems]

In view of this, as a result of various studies, the present invention was developed based on changes in casting conditions,
In particular, the extracted heat φ per unit time changes due to changes in casting speed, and this causes uneven thermal stress in the ingot near the molten metal solidification zone, resulting in thermal strain inside the ingot. We discovered that there are differences in tensile strength and electrical conductivity depending on the magnitude of this thermal strain, and as a result of further investigation, we found a way to stabilize the transmission characteristics of cables and to easily manufacture cables with various transmission characteristics. This method has been developed to control the performance of solidified materials.

That is, one of the control methods of the present invention is characterized by controlling the tensile strength and electrical conductivity of the directionally solidified material cast by the unidirectional solidification method by the solidification rate during casting. .

Another control method of the present invention is that the tensile strength of the unidirectionally solidified material is determined by the solidification rate during casting and the processing rate during processing in the unidirectionally solidified material that is cast using the unidirectional solidification method and processed into an ingot. It is characterized by controlling the electrical conductivity.

[For production]

Long materials of directionally solidified ingots, including single crystals, are produced by continuous casting using a heated mold, moldless rotary casting using the Czochralski method, Bridgman method, and the like. By controlling the casting conditions, particularly the casting speed, to a constant value, the thermal strain inside the ingot can be made uniform, and the performance (tensile strength and electrical conductivity) of the ingot can be stabilized. In addition, by changing the casting speed, it is possible to create castings with different performance by varying the thermal strain inside the ingot. Furthermore, by controlling the processing rate in processing the ingot, its properties (tensile strength and electrical conductivity) as a unidirectionally solidified material can be controlled again.

Example 1 A unidirectionally solidified ingot of oxygen-free copper having a diameter of 1.5 m was produced by a casting method using a heated mold. That is, as shown in Fig. 1, a heating element (1) is installed around the inner diameter of 1.5 mm and outer diameter of 3 mm.
0. A SiC mold (2) was attached to the side wall of the casting furnace (3) below the surface of the molten metal (4), and a cooling device (5) was installed near the outlet of the mold (2).

In this way, the inner temperature of the mold (2) is heated to 1200'C, and the amount of oxygen is 3
ppm of molten copper (4) is supplied, and the molten copper (4) is caused to flow into the mold (2). On the other hand, at the outlet of the mold (2), the drawn ingot (6) is cooled by water spouted from the cooling device (5), and the molten copper (
4) Solidify. The ingot (6) is pulled out by pinch rolls (7).

In this way, the casting speed is increased by increasing the amount of water jetted from the cooling device, and the number of rotations of the pinch rolls is gradually increased to 100.
Varying from an/min to 520 s/min,
An oxygen-free copper ingot with a unidirectional solidification structure and a diameter of 1.5 m was obtained.

The number of crystal grains in the cross section of the ingot obtained at each casting speed was 1 to 2.

Next, a unidirectionally solidified ingot of oxygen-free copper having a diameter of 1.5 mm was produced by a moldless rotary casting method applying the Czochralski method. That is, as shown in Fig. 2, a hole is made in the furnace plug (8) of the casting furnace (3) holding the molten copper (4) containing 131)I)m of oxygen, and the cooling device (5) is lowered through the hole. The oxygen-free copper rod (9) is inserted from above so as to be located in the center of the cooling device (5), and brought into contact with the hot water surface. In this state, while cooling the copper rod (9) by blowing N2 gas from the cooling device (5), it is pulled up by the rotary air chuck (10) above the furnace lid (8) and unidirectionally solidified ingot (6
) was obtained. In the top view, (11) indicates a heat insulating material.

In this way, the casting speed, that is, the pulling speed of the rotary air arch, was increased from 50 turns/min to 170 turns/min.
The oxygen-free copper ingot with a unidirectional solidification structure and a diameter of 1.5 m was obtained. The number of crystal grains in the cross section of the ingot cast at each casting speed was 1 to 2 g.

The tensile strength and electrical conductivity of ingots with a diameter of 1.5 mm obtained by both of the above casting methods were measured, and the relationship with casting speed is shown in FIGS. 3 and 4. Figure 3 shows the relationship between casting speed and tensile strength, and Figure 4 shows the relationship between casting speed and electrical conductivity.As is clear from both figures, as the casting speed shifts from low to high speed, The tensile strength (Ky/i) increases and the electrical conductivity (
%IAC3) is found to decrease.

Furthermore, the ingots obtained at each casting speed were cut into 100 m lengths, and the attenuation was measured over a wide range including audio frequencies. The relationship between the casting speed and the amount of attenuation is shown in Figure 5.

As is clear from the figure, the attenuation amount of the low-speed cast material is small and stable, and as the casting speed shifts from the low speed side to the high speed side, the attenuation amount increases.

From the above experimental results, the relationship between casting speed, tensile strength, electrical conductivity, and attenuation ♀ can be quantitatively understood.

Based on this, the target value of tensile strength is 12KI/mr4 in the low speed casting region where frequency attenuation is small and stable.
, target value of conductivity 100.9%lAC3,50h++z
In order to obtain an ingot with a target value of attenuation of 0.0055 dB, continuous casting equipment using a heating mold was used to
Casting was carried out for 100 hours at a casting speed of m/min to produce an oxygen-free copper ingot with a length of 1200 m and a diameter of 1.5 m. About this tensile test piece.

Test pieces for conductivity and test pieces for attenuation measurement were taken alternately and measured. As a result, the tensile strength was 11.8 to 12
．． 3Kg/m, conductivity 100.8-101.1%lA
It can be seen that the amount of reduction in C3 is in the range of 0.0052 to 0.0057 dB, which agrees well with the results shown in FIGS. 3 to 5.

In addition, using a moldless rotary casting equipment, similar long-time casting was carried out at a casting speed of 100 m/min, and similar measurements were carried out, but the results were similar to those shown in Figures 3 to 5. Agreed.

In this embodiment, a small-diameter ingot with a diameter of 1.5 mm has been described, but the present invention can be applied not only to ingots having a circular cross section but also to strips and plates.

Example 2 Using continuous casting equipment using a heating mold and moldless rotary casting equipment, casting speed was 100 #/min, 200 mm/min.
min and 400 #/min in the same manner as in Example 1, with a diameter of 1.5. Oxygen-free copper ingots were manufactured, and ingots having the performance shown in Table 1 were obtained.

Table 1 Using the above three types of ingots, 5.10.15 and 20.
% processing rate (area reduction rate), tensile strength, electrical conductivity, and 50kHz for a sample of length 100 mm.
The amount of attenuation in 2 was measured. The results are shown in FIGS. 6 to 8. Figure 6 shows the relationship between working rate and tensile strength, Figure 7 shows the relationship between working rate and electrical conductivity, and Figure 8 shows the relationship between working rate and attenuation.As is clear from the figure, working rate ranges from O to 20%. It can be seen that as the processing rate increases, the tensile strength increases, the electrical conductivity decreases, and the damping rate increases.

That is, it can be seen that the characteristics of the cable can be controlled by processing an ingot whose performance has been controlled during casting and controlling the processing rate.

In this example, the diameter of the ingot was 1.5 m, and each processing rate was added to this to form a wire rod, and the diameter of the wire rod with a processing rate of 20% was approximately 1.34 m. However, the invention is not limited to this, and if the diameter after processing is to be constant, the outer diameter of the ingot may be increased in accordance with the processing rate. For example, if the wire diameter is 1.5 mm by adding a processing rate of 20%, the diameter of the ingot should be approximately 1.68 m.

Further, in this embodiment, an ingot having a circular cross section has been described, but the invention is not limited to this, and the present invention can also be applied to strips or plates.

〔Effect of the invention〕

The tensile strength and conductivity of the ingot, which can be measured with a small amount of material according to the required characteristics of the cable, can be controlled by casting speed.
Furthermore, it is possible to process an ingot with controlled characteristics, and to further control the characteristics by changing the processing rate, which has significant industrial effects such as facilitating the production of high-performance cables.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an example of a continuous casting method for directionally solidified material using a heating mold, Figure 2 is an explanatory diagram showing an example of a moldless rotary casting method for directionally solidified material, and Figure 3 is an explanatory diagram showing an example of a moldless rotary casting method for directionally solidified material. Figure 4 is a diagram showing the relationship between casting speed and the ingot's electrical conductivity, Figure 5 is a diagram showing the relationship between casting speed and transmission signal attenuation, and Figure 6 is the working rate. Relationship diagram between and tensile strength of processed material,
FIG. 7 is a diagram showing the relationship between the machining rate and the electrical conductivity of the workpiece, and FIG. 8 is a diagram showing the relationship between the machining rate and the amount of transmission signal attenuation of the workpiece. 1, heating element 2, mold 3, casting furnace 4, molten copper 5, cooling device 6, ingot 7, pinch roll 8, furnace cover 9, oxygen-free copper rod 10, air chuck 11, heat insulating material Fig. 1 Fig. 2 Figure 3 Issai difference (mm/m1n) Figure 4 M il t 11 I mm /min) No. 5
Figure M jt 111E (mm/m1n) 8th figure Force D Engineering Kei (%) Electrical conductivity (IAC5%) Tensile strength (Kg/mm2)

Claims (2)

[Claims] (1) In the unidirectionally solidified material cast by the unidirectional solidification method,
A method for controlling the performance of a unidirectionally solidified material, which is characterized by controlling the tensile strength and electrical conductivity of the unidirectionally solidified material by the solidification rate during casting. (2) The tensile strength and electrical conductivity of the directionally solidified material are controlled by the solidification rate during casting and the processing rate during processing in the directionally solidified material in which the ingot is processed after casting using the unidirectional solidification method. Performance control method for unidirectionally solidified materials.