JPS59193737A - Continuous casting method of al and al alloy - Google Patents

Abstract

PURPOSE:To improve quality by using a low carbon steel for the belt of a belt wheel type continuous casting machine, and selecting the thickness of the belt and the charging temp. by a mathematical expression so that a casting ingot larger than the size of a casting mold is formed and the ingot is cooled by the tight contact with the casting mold. CONSTITUTION:A metallic endless belt 3 is moved by a pressure wheel 4 in contact with a part of the outside circumferential surface of a rotary wheel 1 for a casting mold having a hollow groove 2 on the outside circumferential surface, thereby forming a water cooled casting mold 5. A melt 7 of Al or an Al alloy is charged through a nozzle 6 into a casting mold 5 from one end thereof and a solidified casting ingot 8 is drawn from the other end. A low carbon steel is used for the belt 3, and the charging temp. and the belt thickness are so selected that the relation between the charging temp. T1 deg.C and the thickness (t)mm. of the belt satisfies the inequalities I when the m.p. or the solidification initiating temp. of the molten metal is designated at T0 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuous casting of A (and A1 alloys), which particularly improves the quality of the ingot, prevents the expansion of defects during subsequent processing, and improves the yield. It is something.

A, e, and A (for continuous casting of alloys, a belt/wheel type is used for casting in a water-cooled mold formed by moving an endless metal belt into contact with a part of the outer circumferential surface of a rotary mold ring having grooves on the outer circumferential surface. A method called a continuous casting method is used, and low carbon steel with a thickness of 2 to 3 mm is usually used for the endless metal belt.

Generally, when casting A (or A) alloy, a solidified shell is generated at the same time as the molten metal is poured into the mold, and from this point on, the solidified shell begins to shrink, creating a minute gap between the mold and the ingot. The gap becomes larger as solidification progresses, and has a negative effect on heat transfer between the mold and the ingot.Such a phenomenon is also observed in the belt-wheel continuous casting method, which affects performance and
There are problems with quality and productivity.

The inventors of the present invention have conducted various investigations regarding this issue, and found that in the belt-wheel type continuous casting method, it is possible to increase the outer dimensions of the solidified shell by selecting the belt thickness and pouring temperature, and the mold-ingot We discovered that it is possible to eliminate the gap in one direction. That is, in the Bell 1 to wheel type continuous casting method, when the molten metal is poured into the mold, heat is taken away from the molten metal by the mold, and the surface layer immediately solidifies to form a solidified shell. On the other hand, the temperature of the mold increases as it absorbs the heat of the molten metal. Low-carbon steel is usually used for the belt that forms part of the mold, and because low-carbon steel has poor thermal conductivity, a temperature difference occurs between the center of the belt that comes into contact with the molten metal and the end that does not come into contact with the molten metal. The difference in thermal expansion is absorbed by the belt expanding outward.

Therefore, even if the pouring temperature of the molten metal is set to a sufficiently high temperature, since the belt has a small heat capacity, the molten metal will not immediately solidify even if it touches bell 1-, while bells 1~ will receive heat and swell outward. In this state, the belt side will begin to solidify. The bulge of the belt increases rapidly when it comes into contact with molten metal, reaches a peak, and then decreases.

The bulge of the belt at its peak is about 0.6mm,
When the produced ingot was examined, it was found that the belt side had a chipped shape of about 0.5#. Cooling water is then applied to reduce the bulge in the belt, and it eventually returns to its original flat state. At this time, the dimensions of the solidified shell are larger than those of the mold in the thickness direction, so after the bell returns to its flat state, the ingot comes into close contact with the belt and the bottom of the concave groove of the rotating wheel. Coagulation is accelerated.

In view of this, the present invention has conducted various experiments on conditions in which the outer dimensions of the solidified shell are larger than the mold thickness, and the belt thickness and pouring temperature are selected to increase the outer dimensions of the solidified shell, and the ingot and mold By improving the adhesion of A℃ and A℃, we learned that cooling efficiency increases and improves productivity and quality.
(A continuous casting method for alloys has been developed, in which a water-cooled mold is formed by moving an endless metal heddle to a part of the outer circumferential surface of a rotary mold ring that has a groove on the outer circumferential surface, and one end of the mold is From A(
Alternatively, in a method in which the molten aluminum alloy is poured and a solidified ingot is continuously produced at the other end, carbon steel is used for the belt, and the molten metal is heated at
Then, the thickness of the bell [- t tnm and the pouring temperature T1℃
The relationship is T+ -To ≧35. ．． ．． -(1) 7-[ The belt thickness and pouring temperature are selected so as to satisfy the following.

That is, the present invention connects a metal endless belt (3) to a part of the outer circumferential surface of a mold rotary ring (1) having a concave groove (2) on the outer circumferential surface as shown in FIG. A method in which a water-cooled mold (5) is formed by moving the mold (5), molten metal (7) is poured from one end of the mold (5) through a nozzle (6), and a solidified ingot (8) is produced from the other end. , belt (3)
Assuming that low carbon steel is used in
The pouring temperature T is adjusted so that the relationship between nm and satisfies the above equation (1).
By selecting I℃ and belt thickness t'mm, the outer dimensions of the solidified shell are larger than the mold size, which improves the adhesion between the mold and the ingot, increases cooling efficiency, and improves the quality of the ingot. It was forced upon me.

To explain this using the example of pure AJ2, if the belt thickness is 2.7 mm, it will be 112,719°C from the above equation (1), and if the pouring temperature is less than 719°C, solidification on the belt surface will occur.
This occurs before the belt swells, and the solidified shell is not larger than the mold size, so the quality of the ingot is not improved. In order to make the outer dimension of the solidified shell larger than the mold size, the pouring temperature should be set to 7.
The temperature must be 19°C or higher.

The present invention will be explained below with reference to Examples.

Example (1) In the belt-wheel type continuous casting machine shown in Fig. 1,
Copper mold rotating ring with a diameter of 1.4 TrL and a thickness of 1, a.
i and a 2.7 mm low carbon steel belt, the belt starts joining at the upper end of the rotating wheel, and the cross-sectional area 2 opens in the horizontal direction.
100. A trapezoidal water-cooled mold of . Manufactured.

In this continuous casting, the pouring temperature, that is, the temperature of the molten metal in the nostle was changed, and casting was performed at a casting speed of 12 yrt/min.
The obtained ingots were hot rolled, and the number of defects generated during the rolling was investigated. The results are shown in Table 1 in comparison with the conventional method.

Table 1 As is clear from Table 1, the pouring temperature to bell 1 is 708°C or higher, which satisfies the above equation (1) when the thickness is 1.8 mm, and the above equation (1) is satisfied when the heald thickness is 2.7 nm. Pouring temperature 71
Those according to the present invention method No. 1 to 7 whose temperature is 9°C or higher,
In all cases, the number of defects is significantly smaller than in conventional methods Nos. 8 to 12, and the ingot temperature is also lower, which indicates that they are beneficial for improving productivity.

Example (2) Using the same belt-wheel type continuous casting machine as in Example (1), an Af-Mq-Si alloy was produced in the same manner as in Example (1).

The amount of Mg and Si was added in the form of MOzsi (7) at 1.3%. The solidification onset temperature of this alloy was 650°C.

Casting was performed at a casting speed of 11 m/min while changing the temperature of the molten metal in the nozzle, and the resulting ingots were hot rolled, and the number of defects occurring during the rolling was investigated. The results are shown in Table 2 in comparison with the conventional method.

Table 2 As is clear from Table 2, when the belt thickness is 1.8 m and the above formula 1) is satisfied, the pouring temperature is 691°C or higher, and the belt thickness is 2.
．． Pouring temperature 10 that satisfies the above formula (1) 7#l/It
Compared to conventional methods Nos. 19 to 22, the number of defects in all of the methods No. 13 to 18 of the present invention, which have a temperature of 8° C. or higher, was significantly lower, and the ingot temperature was lower, resulting in improved productivity. It turns out to be beneficial.

As described above, the method of the present invention significantly improves the quality of the ingot, prevents the spread of defects during subsequent processing, and improves the yield, resulting in significant industrial effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a belt-wheel type continuous casting machine. 1,...Kawa...Rotating wheel for mold 2,...Kawaguchi groove 3,...Machi...Metal endless belt 4,...Kawa...Pressure wheel 5,...・・・
...Mold 6, Nozzle 7, Molten metal 6, Ingot

Claims (1)

[Claims] A water-cooled mold is formed by bringing an endless metal belt into contact with a part of the outer peripheral surface of a rotating mold ring having a groove on the outer peripheral surface, and AJ2 or A (alloy molten metal) is poured from one end of the mold. In a method of pouring molten metal and continuously producing a solidified ingot from the other end, if low carbon steel is used for the belt and the melting point or solidification start temperature of the molten metal is To°C, then the belt thickness tmll+ Pouring temperature T
A (and 8) continuous casting method for alloys, characterized in that the belt thickness and pouring temperature are selected so that the +-°C relationship satisfies T+ -To ≧ 35 t.