JPS6133735A - Method and device for continuous casting of metal - Google Patents

Abstract

PURPOSE:To form a billet into the uniform structure having a good casting surface without the shift of the solidification center by deviating the solidification start position in the lower part of a water-cooled metallic mold for horizontal casting inserted with a refractory plate material in the outlet for a moltem metal by the projection of the refractory plate material thereby making uniform the progression of the solidification on the periphery and preventing breakout. CONSTITUTION:The inside mold wall surface in the lower part of the water- cooled metallic mold 1 for horizontal casting inserted with the refractory plate material 7 in the outlet 8 for the molten metal of a tundish 10 is covered by the overhang part 6 of the material 7 to deviate the solification start position in the lower part. The molten metal 9 in the mold 1 contacts more thoroughly with the mold 1 the nearer the lower part and the solidification progresses earlier in said part but the progression of the solidification on the periphery of the mold 1 is made uniform by the overhang 6, by which the feeding of a lubricating agent 6 is also made uniform on the periphery. The breakout owing to burn-on, etc. is prevented. A casting ingot 14 is thus solidified to have the good casting surface 15 and to have the uniform structure without the deviation of the solidification center.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved horizontal continuous casting method and apparatus for metals, particularly light metals such as aluminum or its alloys.

[Conventional technology]

Generally, in horizontal continuous casting of metal, a long ingot in the shape of a cylinder, a prism, or a hollow cylinder is manufactured from molten metal through the following process. In other words, the molten metal enters the tundish, which stores the molten metal, passes through a refractory passageway into a forcedly cooled cylindrical mold installed almost horizontally, where it is cooled and a solidified shell forms on the outer surface of the molten metal body. It is formed. A coolant such as water is directly radiated onto the ingot that has been pulled out of the mold, and the metal is continuously drawn out as the metal solidifies inside the ingot.

Horizontal continuous casting of such metals inevitably involves theoretical difficulties. Firstly, because the mold is installed horizontally, the molten metal inside the mold is pressed against the inner wall at the bottom of the mold by gravity, resulting in an uneven cooling system in which the cooling within the mold is stronger at the bottom and weaker at the top. A lance occurs, and as a result, the final solidification position shifts upward from the axis of the ingot, making it impossible to obtain an ingot with a homogeneous structure.

Second, in order to prevent the molten metal from sticking to the mold wall, lubricating oil is injected from the inner peripheral wall at the inlet end of the mold, but if it is injected uniformly all around the mold inner wall, the lower wall surface will be more The oil tends to flow down and the lubricating interface becomes non-uniform. As mentioned above, in the lower part of the mold, the molten metal and the mold wall are in close contact, and there is no clearance between the solidified shell and the mold wall, so lubricant oil does not flow in and the solidified shell ruptures due to seizing, causing the unsolidified molten metal to flow out. (so-called breakout), resulting in large casting surface defects or even further progressing to the point where casting is no longer possible.

In order to overcome these essential problems in the horizontal continuous casting method of metals, several solutions have been proposed in the past. The Japanese Patent Publication No. 39-2371.0 places the orifice opening for injecting molten metal into the mold below the axis of the mold, and the Japanese Patent Publication No. 4-5-41.509 places the orifice opening for injecting molten metal into the mold below the axis of the mold. Although a fence is installed at the inlet, the method is to direct the flow of high-temperature molten metal downward at the mold inlet, thereby easing downward cooling, and it does have the appropriate effect of bringing the final solidification position closer to the axis of the ingot. However, the above-described strong contact between the molten metal and the lower inner wall of the mold has not been solved, and the homogenization of the ingot structure has been insufficient.

There is also a proposal to change the distribution of lubricating oil between the upper and lower parts of the mold, as in Japanese Patent Publication No. 4.6-28889, but due to the effect of gravity acting inside the mold, even if a considerable amount of oil is supplied. It is difficult to form a uniform lubricating interface. Moreover, if the amount of oil is too large, a wavy pattern called oil fold occurs on the casting surface, resulting in defects, and this improvement measure has not been sufficiently effective in practical use.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned problems in the conventional horizontal continuous metal casting method, namely, the cooling of the molten metal in the mold.
Horizontal continuity of metal that eliminates the unevenness of the lubricating interface between the lance and the inner wall of the mold, homogenizes the ingot structure, eliminates casting surface defects and breakouts, and enables stable casting of high-quality ingots. The object of the present invention is to provide a casting method and apparatus.

[Failure to solve the problem]

In order to achieve the above object, the inventors of the present invention have conducted various studies and have realized an improved method and apparatus on a practical scale. The configuration of the present invention will be explained below.

Functionally, the method and device of the present invention can be summarized as follows: The amount of heat absorbed from the forcedly cooled inner wall of the mold is suppressed below the mold axis compared to above the mold axis, thereby eliminating the unbalanced cooling around the entire circumference. There it is.

That is, the first aspect of the present invention is a horizontal continuous metal casting method in which a molten metal outlet of a tundish is connected to a refractory plate having a molten metal inlet opened at the upstream end of a forced-cooled cylindrical mold. , a horizontal continuous casting method for metal, characterized in that the horizontal contact position between the inner wall of the mold below the axis of the mold and the metal body is shifted toward the downstream end of the mold to limit the amount of cooling. A second aspect of the present invention relates to an apparatus embodying the above method, characterized in that a fireproof and heat insulating coating is applied to the inner wall of the mold from the upstream end below the axis of the mold to the downstream end. It is a horizontal continuous device.

In the method of the invention, the means for shifting the horizontal contact position between the inner wall of the mold and the metal body below the axis of the mold starts at the upstream end of the mold, that is, the end of the connection with the refractory plate. Here, the metal body refers to either a columnar molten metal in a mold, a molten metal with a solidified shell formed on the outer surface, and a solidified ingot in the process of solidification inside. The length to suppress horizontal contact varies depending on the type of Metal 1 alloy, molten metal temperature, solidification characteristics, diameter of the columnar ingot, thermal balance of the mold block, etc., but generally a thin solidified shell is formed on the outer surface. It is appropriate to set the limit to the current position. Such a contact suppression area may have a linear or curved shape in plan view, and in particular, in a cylindrical mold, it is more preferable to form it in an arc shape with the apex at the lowest bottom of the mold.

[Examples and effects]

The method and apparatus of the present invention will be described below based on examples and with reference to the drawings, but the present invention is not limited thereto. FIG. 1 shows a vertical cross-section of a main part of a horizontal continuous casting apparatus embodying the present invention. An aluminum alloy mold 1 has a cylindrical inner wall surface 3 cooled by an annular cooling water jacket 2 . The molten aluminum alloy is stored at a predetermined level in the tundish 10 via a melting and holding furnace (not shown) and, if necessary, a degassing and descaling device. The molten metal flows from the outlet 11 to a fire-resistant conduit 10/
The molten metal flows into the mold 1 via the refractory plate body 7 through the molten metal flow port 8 and accumulates in the mold 9 . The outer periphery of the molten metal 9 contacts the forcedly cooled cylindrical inner wall surface and is cooled to form a solidified shell, which is drawn out to the downstream end of the mold while thickening, and is directly cooled by the supply of cooling water key 2 to form a cast surface. A columnar solidified ingot 14 having a diameter of 15 is formed.

In accordance with a conventional method, lubricating oil passes from the oil supply pipe 5a inside the upstream end of the mold, through the annular distribution pipe 5b, and through the oil supply thin pipe 5c to the inner wall surface 3 of the mold.
is supplied to In this embodiment, the structure of the present invention is such that an overhang 6 is provided on the surface of the refractory plate below the axis of the cylindrical mold to be fitted into the mold, thereby increasing the inner wall surface of the mold.
The position of contact between the metal and the molten metal is shifted to the downstream area.

FIG. 2 is an enlarged view of the upstream end of the mold shown in FIG. 1, and the refractory plate 7 is made of Marinite, a commercially available material that is well known as a material that has fireproof insulation properties, does not get wet with molten aluminum alloy, and has corrosion resistance. It is finished formed by machine cutting, and the overhanging part 6 is connected to the oil supply thin pipe 5c via the annular distribution pipe 5b.
It flows into the clearance 16 as shown in FIG.

By using the method and apparatus of the present invention described above, aluminum alloys 6063 and 4032 can be made with a diameter of 2 inches and a diameter of 8 inches.
As a result of continuous casting of the second billet, there were no operational problems such as breakouts, and a high-quality product with a uniform, smooth casting surface all around and a uniform internal metallurgical structure was obtained. In contrast, red was formed and the internal structure was heterogeneous with the center of coagulation shifted upward.

In the above embodiment, the fire-resistant heat-insulating coating was formed by fitting the overhang 9 and the mold wall with a slight clearance between them and the mold wall. It is also possible to make the 16' side dish stick closely together, and it is not limited to the molded body cut out from the rock material, but it is also possible to apply a method of coating and fixing a monolithic refractory material (castable, etc.) with fire-resistant and heat-insulating properties to the inner wall of the mold, or a method that can be used. A method such as fitting and fixing flexible fireproof heat insulating felt is applied.

The shape of the fireproof heat insulating coating area is as described above, and some preferred examples are shown in FIG. 3 (a) to (,). In the figure, the upper row is a longitudinal cross-sectional view of the mold, and the lower row is a plan view of a horizontal cross-section of the corresponding mold axis 1a. As shown in the figure, the thickness of the refractory heat insulating coating 17 may decrease linearly or curvedly on the surface of the mold inner wall 3/n from the upstream end of the mold, that is, the base of the refractory plate 7 toward the downstream end. , a height is placed at the beginning of the coating.

In terms of a plan view, it is formed into a rectangular shape with a constant length from the upstream end, a triangular shape with the bottom of the mold as its apex, or an arc shape. Rectangular cylindrical mold [Effect of the invention] As mentioned in the above embodiments, if the method and apparatus of the present invention are applied to horizontal continuous casting of metals, especially light metals such as aluminum or its alloys, In comparison, the surface of the resulting ingot is smooth all around the circumference, requiring less skin removal before plastic working, and the solidification center does not shift, resulting in an ingot with a homogeneous structure throughout the entire cross section. can get. In addition, the cooling is uniform all around, the lubricating fluid is well distributed, and there are almost no operational problems such as breakouts due to seizure, which greatly contributes to improving productivity and reducing costs.

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[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a horizontal continuous casting apparatus showing an embodiment of the present invention, and FIG. 2 is an enlarged view of the vicinity of the upstream end of the mold of the apparatus shown in FIG. FIG. 3 is a schematic diagram showing another embodiment of the shape of the fireproof and heat insulating coating area of the present invention. 1... Forced cooling cylindrical mold, 1a... Mold axis,
3... Mold inner wall surface, 4... Mold upstream end, 5c...
Refueling thin tube, 6... overhanging part, 7... fireproof plate body,
9...Mold white metal molten metal, 10...Tandish,
17...Fireproof insulation coating.

Claims (1)

[Claims] 1. A horizontal continuous metal casting method in which a molten metal outlet of a tundish is connected to a tundish by sandwiching a refractory plate having a molten metal inlet at the upstream end of a forced-cooled cylindrical mold, A method for horizontal continuous casting of metal, characterized in that the horizontal contact position between the inner wall of the mold and the metal body below the axis of the mold is shifted toward the downstream end of the mold to limit the amount of cooling. 2. In a horizontal continuous metal casting device in which the molten metal outlet of a tundish is connected to the tundish by sandwiching a refractory plate with a molten metal inlet opened at the upstream end of a forced-cooled cylindrical mold, 1. A horizontal continuous metal casting apparatus, characterized in that the inner wall of the mold is coated with a fireproof and heat insulating coating from a lower upstream end to a downstream end.