JPS6356334A - Horizontal continuous casting method for hollow aluminum material - Google Patents

Abstract

PURPOSE:To cast a good-quality hollow aluminum material by force cooling only the cylindrical casting mold and cooling the outside peripheral face of a drawn-out ingot at the time of supplying molten aluminum between the horizontally disposed cylindrical mold and core and casting the hollow material. CONSTITUTION:The molten aluminum 1 supplied into a tundish 2 is supplied between the cylindrical casting mold 5 and the core 6 through a hole 4 of a header plate 3 disposed in front of the tundish. Cooling water 7 is kept run in the mold 5 and is supplied from discharge holes 8 toward the ingot drawn from the mold 5. The molten metal 1 filling the spacing between the mold 5 and the core 6 is, therefore, cooled by the mold 5 to form a solidified shell on the outside peripheral side. The solidified shell increases its thickness as the molten metal progresses to the outlet side. The molten metal is directly cooled by the cooling water when said metal is emitted from the mold 5 so that the solidification progresses further to the inside. The good hollow aluminum material 9 is castable if the length of the core 6 is set at about >=1.2 times the length of the mold 5 and the taper angle alpha thereof at about >=3 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for horizontal continuous casting of aluminum (aluminum or aluminum alloy) hollow materials.

[Prior art and its problems]

Traditionally, aluminum hollow forged products such as VTR cylinders were
It is manufactured by cutting a hollow blank from a solid cast material and then cold forging it. However, this method has the disadvantage that the number of forgings is increased and scraps are generated due to die cutting, resulting in high costs. In addition, there is a method of using an extruded tube or a drawn tube as the blank material, but this method is also not practical because the cost of the material itself is high.

To solve these problems, it is effective to use relatively small-diameter hollow cast materials as a material, but conventionally, an appropriate method for continuously casting relatively small-diameter hollow aluminum materials has not yet been developed. do not have.

[Means for solving problems and their effects]

In order to solve the problems of the prior art as described above, the present invention provides a method for horizontal continuous casting of aluminum hollow materials. In a method of continuously casting aluminum hollow material by supplying molten aluminum between a cylindrical mold and a core, and cooling the molten aluminum, the cylindrical mold is forcedly cooled without forced cooling of the core. By cooling the outer circumferential surface of the ingot pulled out from the cylindrical mold with cooling water, heat is extracted from the outer circumferential surface of the ingot to advance solidification, and the final solidified part is formed on the above-mentioned core. It is characterized by continuous casting.

When producing hollow aluminum materials by horizontal continuous casting, it is effective to forcibly cool both the cylindrical mold and the core for efficient cooling. However, when the core is cooled, cooling water flows into the hollow material, which poses a problem in how to dispose of the cooling water when cutting the hollow material. The reason why relatively small-diameter hollow aluminum materials have not been produced industrially by the horizontal continuous casting method is thought to be because it is difficult to cool the core.

According to the method of the present invention, since the core is not cooled, the configuration of the casting device and the casting method are not simplified.
It has been found that it is possible to cast aluminum hollow materials of good quality.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG. The molten aluminum 1 is supplied into the tundish 2 via a melting and holding furnace (not shown) and a degassing/filtering line, and is passed through a hole 4 formed in a hollow plate 3 on the front side of the tundish 2 into a cylindrical mold 5 and a core 6. supplied between. The cylindrical mold 5 is made of prepared alloy, and has cooling water 7 flowing therein, and has a cooling water outlet 8 formed toward the ingot drawn out from the cylindrical mold 5.

The core 6 is made of graphite (SiC or SiN may also be used), is fixed to the heel plate 3, and is not cooled.

Since the molten metal 1 filled between the cylindrical mold 5 and the core 6 is cooled by the cylindrical mold 5, a solidified shell is formed on the outer circumferential side, and as the solidified metal 1 moves inside the cylindrical mold 5 toward the exit side, it forms a solidified shell. It's getting thicker. When the solidified shell reaches a certain thickness, it comes out of the cylindrical mold 5, is directly cooled by cooling water, and solidification progresses further inside.

Since the core 6 is not cooled, the molten metal 1 does not begin to solidify from the portion in contact with the core 6. In other words, since solidification proceeds only from the outer circumferential side, if the length of the core 6 is made sufficiently long, the final solidified portion can be formed on the core 6. Therefore, the inner peripheral surface of the hollow material is formed by the core 6, and the aluminum hollow material 9 can be cast.

Note that the core 6 is preferably longer than the cylindrical mold 5,
The length of the core 6 is preferably at least 1.2 times the length of the cylindrical mold 5. Further, it is preferable that the outer circumferential surface of the core 6 is a tapered surface as shown in the figure, and the taper angle α is set to 3° or more.

Example 1 Using a copper alloy water-cooled cylindrical mold with an inner diameter of 68 mm and a length of 38 mm, and a graphite core with a tip outer diameter of 30 mm, a length of 50 mm, and a taper angle of 5°, the outer diameter of J I 36061 alloy was 6.
A hollow member with a diameter of 8 mm and an inner diameter of 30 inches was cast. The core is not cooled or lubricated.

At the start, pouring was started with a starting block machined into a shape into which the core fit inserted into the cylindrical mold, and 30 seconds after the start of pouring, withdrawal was started. When we observed the structure of the hollow material cast by this method, we found that no chill layer was observed near the inner circumferential surface in the steady solidification part, and Puntorai 1-arms could be visually observed on the inner circumferential surface. Histologically, it was confirmed that this was the final coagulation area. The quality of the hollow material means that there is virtually no oxide layer that would be harmful during forging, and there is no need to remove the casting surface from the inner circumferential surface.

Example 2 J I 54032 alloy outer diameter 68 mm, inner diameter 20 mm
A hollow material was cast and its microstructure was compared with a solid ingot of the same material and outer diameter. In the steady solidification part, the average Si particle size is 5 ttm or less, and the maximum is about 10 μm, which is good.
It was confirmed that there was no variation in particle size.

Example 3 In the same manner as in Example 1, a hollow member of J I 52218 alloy with an outer diameter of 68 mm and an inner diameter of 15 mm was cast. The obtained hollow material was homogenized, blank cut, and bonded, then cold forged, then T6 treated and cut to form a V.
It was made into a TR cylinder. This was compared with those produced from conventional solid ingots, and it was confirmed that there were no differences in all evaluation items such as machinability, hardness distribution, and internal structure.

〔Effect of the invention〕

As explained above, according to the present invention, since the core and the inner circumferential surface of the hollow material are not cooled, the aluminum hollow material can be cast relatively easily without the problem of processing cooling water flowing into the hollow material. Can be done. In addition, in this method, the inner circumferential surface of the aluminum hollow material becomes the final solidified part, so there is no structure disorder or chill layer due to discontinuous solidification, and the oxide film layer that causes problems during forging can be virtually ignored. It is possible to obtain aluminum hollow materials of extremely good quality.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a method for horizontal continuous casting of aluminum hollow materials according to an embodiment of the present invention. 1 - Molten metal, 2 - Tandenshi, 3 - Belly plate, 4 - Hole, 5 - Cylindrical mold, 6 - Core, 7 - Cooling water, 8 -
Cooling water outlet, 9 ~ aluminum hollow material.

Claims (1)

[Claims] A method of continuously casting aluminum hollow materials by supplying molten aluminum between a horizontally arranged cylindrical mold and a core from a hole formed in the header plate on the front of the tundish and cooling it. Heat is extracted from the outer circumferential surface of the ingot by forcibly cooling the cylindrical mold and directly cooling the outer circumferential surface of the ingot drawn from the cylindrical mold with cooling water. 1. A horizontal continuous casting method for aluminum hollow material, characterized in that continuous casting is carried out by advancing solidification so that a final solidified portion is formed on the core.