JPH0130579B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a heated mold continuous casting method, particularly a horizontal continuous casting method, for obtaining a unidirectionally solidified ingot with a smooth and beautiful surface.

(Prior Art) With the development of the electronics industry, devices have become smaller and more precise, and strict demands have been placed on the quality of the metal materials used in these devices. Moreover, there has been a demand for materials that are not only free from internal segregation of solutes and impurities, but also free from grain boundaries.

In order to meet these demands for materials,
The inventor of the present application has previously developed a heated mold type continuous casting method (Patent No. 1049149), in which the inner wall of the mold is heated to a temperature above the freezing point of the cast metal. We proposed a continuous casting method that heats the material.

This heated mold continuous casting method is a method for obtaining high-quality ingots with a smooth and beautiful surface, a unidirectionally solidified structure with excellent workability, and no internal casting defects such as segregation or bubbles. It has been attracting attention. In addition, since single crystal ingots can be easily obtained through the competitive growth of crystals during solidification, it has been used to produce plate-shaped ingots as sputtering targets and materials for thin foils. In particular, the patent-pending horizontal heating mold continuous casting method allows the obtained ingot to be taken out horizontally as it is and then directly fed to a rolling mill or wire drawing machine for processing. It has been used as a method for manufacturing thin wire materials made of zinc, tin, and their alloys. This horizontal heating mold type continuous casting method is carried out from the molten metal holding container 6 to the molten metal inlet 7 of the mold, as shown in FIG.
After the molten metal 8 supplied through the mold 1 forms a solidified layer on the tip of the ingot dummy 3 at the outlet end of the mold 1, an ingot 9 can be obtained by pulling out the ingot dummy 3 with the pinch rolls 5. can. Note that 2 represents a heating element and 4 represents a cooling device.

(Problem to be Solved by the Invention) However, in the method with the above configuration, since the inner wall of the mold 1 is maintained at a temperature higher than the solidification temperature of the cast metal, a solidified shell along the mold inner wall is not formed, and solidification occurs inside the mold. The ingot 9 moves forward at the tip of the ingot avoiding the wall surface.
Since the molten metal leaves the mold outlet end with its surface layer covered by the liquid film 10, there is a risk that the molten metal will flow out from the lower end of the mold 1.

Therefore, it was necessary to control the casting conditions extremely slowly and strictly to prevent breakouts. For example, for Sn or Sn-30%Zn alloy with a diameter of 5 mm, the casting process was performed at a rate of 150 mm/min and a diameter of 5 mm. 5
mm Cu at slow speeds such as 200 mm/min; at higher speeds, the molten metal often broke out from the lower end of the casting outlet, and the casting operation had to be interrupted.

SUMMARY OF THE INVENTION Therefore, the present invention provides a method that eliminates the problems of the prior art and enables unidirectional solidification casting with a smooth, beautiful surface and no internal defects.

(Means for Solving the Problems) In order to solve the above problems, the present invention sets an ingot dummy at the outlet end of a horizontal hollow heating mold for supplying molten metal from one end and obtaining an ingot from the other end. death,
After filling the mold with molten metal, casting is performed with the molten metal level in the molten metal holding container serving as the molten metal supply source at a level lower than the upper end of the mold outlet.

(Function) With the above configuration, the pressure of the molten metal applied to the lower end of the mold outlet is reduced, preventing the molten metal from spouting, that is, breaking out, at the lower end of the mold outlet during casting, and increasing the casting speed of the ingot. Therefore, the above-mentioned problem can be eliminated.

(Example) FIG. 1 is a longitudinal sectional front view of the main part of a horizontal heating mold type continuous casting apparatus showing the method of the present invention. In the figure,
1 is a horizontal hollow heating mold equipped with a heating element 2.
3 is an ingot dummy, and 4 is an ingot cooling device that blows out water cooling spray, gas, or mist. 5 is a pinch roll for pulling out the ingot.
6 is a molten metal holding container, and mold 1 is attached to the side wall of the container.
The molten metal inlet 7 is provided at a level below the upper end of the mold outlet. That is, the molten metal 8 in the molten metal holding container 6 rises once through the molten metal inlet 7 of the mold 1 as shown by the arrow, and then flows horizontally toward the mold outlet end. On the other hand, the other side wall of the molten metal holding container 6 is provided with a molten metal overflow port 11 and an injection port 12 in order to keep the molten metal level constant.

Next, regarding the casting operation, first, the overflow port 11 is closed, and the molten metal is injected from the injection port 12 to raise the molten metal level in the molten metal holding container 6 and fill it up to the outlet of the mold 1. In this case, the outlet is blocked in advance by the ingot dummy 3, so air remains in the outlet, but there is a gap between the dummy 3 and the outlet that allows air to flow (completely sealed). ). Therefore, when pulling out the dummy 3, the outlet portion is completely filled with molten metal.Therefore, after forming a solidified layer at the tip of the ingot dummy 3, the surface of the molten metal in the molten metal holding container 6 is turned into the mold 1. The ingot 9 can be continuously cast by lowering the ingot dummy 3 to a level below the upper end of the outlet (opening the overflow port 11) and pulling out the ingot dummy 3.

Concrete Example 1 An Sn-30% Zn alloy was continuously cast using an apparatus as shown in FIG. 1 having a heated graphite mold with an inner diameter of 5 mm. The mold was heated by wrapping a nichrome wire around it. A brass wire with a diameter of 5 mm was used as an ingot dummy.
Insert the molten metal level control rod into the molten metal surface heated to 360℃ in the molten metal holding container, raise the molten metal level to a level 10 mm above the upper end of the mold outlet, and then raise the molten metal level to 14 mm.
The ingot dummy was lowered, the ingot dummy started cooling, and then pulled out. As a result, it was possible to perform casting at a casting temperature of 320°C and a speed of 1500 mm/min.

Specific Example 2 Pure Cu was continuously cast using an apparatus as shown in FIG. 1 having a graphite heating mold with an inner diameter of 5 mm. The mold was heated by a silicon carbide heating element. The mold and molten metal holding furnace were kept in a nitrogen atmosphere to prevent oxidation. A copper wire with a diameter of 5 mm was used as an ingot dummy. A graphite level control rod is inserted into the molten metal heated to 1100℃ in the molten metal holding furnace, and the molten metal level is raised to a level 10 mm above the upper end of the mold outlet.
The molten metal level was lowered by 13 mm, cooling of the ingot dummy was started, and it was pulled out. As a result, 1000 at a mold temperature of 1085℃
Casting could be performed at a speed of mm/min.

(Effects of the Invention) As explained in detail above, according to the present invention,
The molten metal pressure applied to the lower end of the mold outlet can be significantly reduced compared to the conventional method shown in FIG. Furthermore, if the molten metal level in the molten metal holding container is lowered to a level below the upper end of the mold outlet, not only will oxides on the top of the molten metal flow into the mold from the molten metal holding container, but also there will be a gap between the mold outlet and the ingot. However, according to the present invention, after the mold is once filled with molten metal, the surface of the molten metal in the molten metal holder is adjusted to the upper end of the mold outlet. Even when the ingot is lowered to the following level, as the ingot is pulled out from the mold outlet, the molten metal is sucked into the mold, the mold is filled with molten metal, and the resulting ingot faithfully reproduces the cross-sectional shape of the mold outlet. can maintain its shape. Also, if the molten metal level drops excessively, a gap will form between the top of the ingot and the mold, but in this case, the molten metal level in the molten metal holding container is raised and the mold is filled with molten metal without interrupting work. Afterwards, the molten metal level is lowered to the extent that there is no gap between the mold and the top of the ingot.
This is an epoch-making technology that significantly improves the productivity of high-quality unidirectionally solidified ingots, such as by allowing continuous casting without interrupting the casting operation.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view of the main part showing an embodiment of the heating mold type horizontal continuous casting method for ingots of the present invention, and Fig. 2 is a longitudinal sectional front view of the main part showing the conventional heating mold type horizontal continuous casting method. . 1... Heating mold, 2... Heating element, 3... Ingot dummy,
4... Cooling device, 5... Pinch roll, 6... Molten metal holding container, 7... Molten metal inlet of mold, 8... Molten metal, 9... Ingot, 10... Liquid film.

Claims (1)

[Claims] 1. An ingot dummy is set at the outlet end of a horizontal hollow heating mold for supplying molten metal from one end and receiving an ingot from the other end, and the mold is filled with molten metal from the inlet located at a level below the outlet end. After that, the surface of the molten metal holding container serving as the molten metal supply source is lowered to a level lower than the upper end of the mold outlet, and casting is performed.