JPH0576991A - Apparatus for casting steel ingot - Google Patents

Abstract

PURPOSE:To provide an apparatus for casting a steel ingot for a rolling material with high yield by thinning the upper part of an ingot case and also reducing the thickness at the center part of a feeder head flask material. CONSTITUTION:In the apparatus for casting the steel ingot, the upper part of the ingot case 1 is made to thin thickness so as to have the space enabling insertion of a feeder head flask 2 without practically step. Further, the feeder head flask material is made to the cross sectional shape once reducing the thickness from the lower edge toward the upper edge and successively, increasing this thickness, and a feeder head 4 is brought into contact with the feeder head flask material with the reverse taper (necessary to be about 2-3 deg.) compared with the conventional one. By this method, the formation of blow hole and the concentration of a carbon component caused by carburization are limited within only the upper half 41 part of the ingot, and by cutting off the upper half 41 part of the cast ingot at the broken line, the material without any defect is obtd. with high yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a casting apparatus for casting a steel ingot, which comprises an ingot case and a feeder frame.

[0002]

2. Description of the Related Art In ingot casting of steel, how to improve the quality of the shoulder portion of the obtained ingot has always been a big problem. The feeder frame is generally assembled on the ingot case with its lower edge slanted, but on this sloped part and in the vicinity there are blowholes that are probably due to gas traps and the C component is concentrated. It becomes hard and causes scratches when rolling the steel ingot.

Therefore, such defects are removed by a hot scarf method or the like prior to rolling, but there is a limit to the amount that can be removed. Needless to say, if the material is cut off from the shoulder and rolled, the yield is poor and it is disadvantageous.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems as described above, and to prevent the formation of blowholes in the shoulder portion of the ingot and the enrichment of C component ingots. The object is to provide a casting device for a steel ingot.

[0005]

As shown in FIG. 1, a steel ingot casting apparatus of the present invention is a steel ingot casting apparatus in which a feeder frame (2) is assembled to an ingot case (1). , A space (11) having a thin upper part and capable of accommodating a feeder frame substantially without a step, and a feeder frame material (21)
Is characterized by having a cross-sectional shape in which the wall thickness decreases and then increases from the lower edge (22) to the upper edge (24).

In the feeder frame material (21), the wall thickness linearly decreases from the lower edge (22) to almost the center (23) as shown in FIG. 1, and then linearly increases from there. In addition to the one having a cross-sectional shape reaching the upper edge (24), one having a change in wall thickness as shown in FIG. The point is that the space for casting and filling molten steel in the lower part of the feeder frame has a shape that expands upward. The feeder frame material can be manufactured by a known technique using a material similar to the conventional name.

[0007]

When the ingot casting is performed using the conventional feeder frame, as shown in FIG. 3, the gas generated by the thermal decomposition of the feeder frame material is trapped, or the taper portion below the feeder frame is trapped. It was unavoidable that the powder quality for casting adheres and the surface quality of the ingot at that part deteriorates.

The gas generated from the feeder frame material contains a considerable amount of CO and CO ₂ , and if it remains as bubbles (5), of course, it does not affect the molten steel (3). It is considered that the carburizing action causes the above-mentioned thickening of the C component in the shoulder portion of the ingot.

On the other hand, when the casting apparatus of the present invention is used, as shown in FIG. 4, the lower half (41) of the feeder (4) is in contact with the feeder frame material having a taper opposite to the conventional one. , The powder does not vitrify smoothly to form a thin film and does not adhere in large amounts. Even if gas is generated due to decomposition of the feeder frame, it easily floats up and separates, so of course there is no formation of blow holes. , C component is not thickened by carburizing. In the upper half (42) of the riser, segregation of alloy components occurs in addition to such defects. No material is obtained.

The reverse taper of the feeder frame material which gives such an effect is required to be 2 to 3 ° at the angle θ in FIG. The larger the angle θ is, the more reliable the effect is. However, it is meaningless to increase the angle θ beyond a certain degree, and there is a restriction based on the wall thickness of the feeder frame material. The preferred range is 10 to 15 °.

[0011]

Example A slag wool was mixed with silica sand, and a kneaded product containing a synthetic resin binder was placed in a mold and cured to produce a feeder frame material. The thickness of the upper and lower edges is 35 mm, the thinnest part of the central part is 20 mm, and the inverse taper angle θ is 1
It is 2 °. On the other hand, a 4.6 ton ingot case was remodeled and the upper part was shaved by a depth of 35 mm, and the above feeder frame material was pushed thereinto to form the casting apparatus of the present invention.

Bearing steel SUJ2 in an electric arc furnace with a capacity of 70 tons
Was used and the casting equipment was used to cast it into a 4.6 ton ingot.

When the conventional casting apparatus shown in FIG. 3 was used, about 7% of the top portion of the ingot was cut off, and the defective portion was removed (about 1%) before rolling. When the casting apparatus of the invention was used, the amount of defective portions removed could be reduced by about 70% of the conventional amount, and the time required for maintenance was less than half.

[0014]

When the ingot casting of steel is carried out by using the casting apparatus of the present invention, the top portion to be cut off can be made small, and therefore a material to be used for rolling can be obtained with high yield. This contributes to the cost reduction of steel product manufacturing, together with the simple maintenance work for removing defects on the surface of the ingot.

Although this casting apparatus can be used for any steel, it is particularly effective for a steel type having a high carbon alloy composition in which the concentration of C in the shoulder portion of the ingot causes a serious problem.

[Brief description of drawings]

FIG. 1 is a development view showing a cross-sectional shape of an ingot case and a feeder frame material for a typical example of a casting apparatus of the present invention.

FIG. 2 is a sectional view corresponding to a part of FIG. 1, showing another example of the feeder frame material used in the casting apparatus of the present invention.

FIG. 3 is a conceptual cross-sectional view of essential parts showing a situation of steel ingot casting using a conventional casting apparatus.

FIG. 4 is a sectional view corresponding to FIG. 3, showing a situation of ingot casting of steel using the casting apparatus of the present invention.

[Explanation of symbols]

1 ingot case 2 feeder frame 21 feeder frame material 22 lower edge 23 center
24 Upper edge 3 Molten steel 4 Feeder 41 Lower half of feeder 42 Upper half of feeder 5 Air bubbles

Claims (1)

[Claims] 1. A steel ingot casting apparatus in which a feeder frame is assembled in an ingot case, wherein the ingot case has a thin upper portion and has a space capable of accommodating the feeder frame substantially without steps, and the feeder frame material Has a cross-sectional shape whose wall thickness decreases and then increases from the lower edge to the upper edge.