JPH0626759B2 - Multi-continuous casting method and equipment for different materials - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multi-continuous casting method for continuously casting metals of different materials.

2. Description of the Related Art In recent years, the development of multi-continuous casting method in the field of metal production, especially ironmaking has been remarkable. One of them is multi-continuous casting, which is a method of continuously casting a plurality of melted charges, and has effects such as improvement of operating rate, improvement of yield, and reduction of various basic units. Multi-continuous casting is performed not only during melt charging of the same material but also during melt charging of different materials. That is, when the continuous casting of the same material cannot be performed due to process restrictions, the continuous casting of different materials is performed. In this case, it is necessary to take measures to minimize the generation of so-called boundary material, which is an incompatible portion due to mixing of different materials at the boundary between the preceding dissolution charge and the subsequent dissolution charge. Although various proposals have been made in the past regarding such measures, a method of inserting a jig called a partition plate at the boundary between the preceding melting charge and the following melting charge to prevent mixing of different materials as much as possible, and It is roughly divided into a method of modifying the dish to prevent mixing of different materials as much as possible. The former method is disclosed in JP-A-55-42145,
It has already been introduced in JP-A-55-8329 and the like, and the latter method has already been introduced in JP-A-53-11225 and JP-A-56-1761.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, as described above, the method using a jig called a partition plate stops the withdrawal of the slab when the jig is inserted at the boundary between the preceding melt charge and the subsequent melt charge. In addition, since a large amount of powder is wound around the rear end of the preceding melt-charged slab, there is a problem in that the rear end portion frequently suffers from defects due to ultrasonic inspection. Further, in this method, it is necessary to prepare a large number of partition plates. Further, there is a problem that the method of remodeling a tundish is not practical because the effect of preventing mixing of different materials is not sufficient and the remodeling requires a large amount of cost.

The present invention provides a means for solving the above-mentioned problems, and when performing multi-continuous casting of dissimilar materials, the solidified shells facing each other by pressing the boundary portion of the dissimilar materials immediately below the mold are provided. A continuous casting method of different materials characterized by closely contacting, and a pair of pressing tools for pinching the solidified shell and a drive device for driving the pair of pressing tools are provided in the slab passage directly under the mold. The main point is a multi-continuous casting machine with different materials.

The present invention will be described with reference to the drawings. FIG. 1 is an embodiment of the apparatus of the present invention for carrying out the method of the present invention.
The molten steel injected into the mold (4) by the pouring nozzle (3) is cooled by the molds (4) and (4) to form a solidified shell (21) and become a cast piece (2). Immediately below the mold (4) (4) and pressing tools (6) (6) which are a pair of rollers for narrowing the solidified shell (21) on both sides of the passage of the slab (2), and the pressing Drive devices (7) (7) which are fluid cylinders for driving the tools (6) (6) are provided. Pressing tool
(6) (6) is normally open, the slab with the solidified shell (21) formed in the mold moves downward, further moves along a number of support rollers (5), cutting It is sent under a machine (not shown) and cut by the cutting machine to obtain a steel semi-finished product. When the casting of the molten steel charge of one material into the mold (4) from the casting nozzle (3) is finished and the casting of the molten steel charge of another different material is started, the molten steel of the preceding one molten steel charge is started. The mixing of (1) and the subsequent molten steel (1) of the molten steel charge of the other different material is started. Driving the driving device (7) (7) when the mixing start portion, that is, the boundary portion of the slab (2) of the different material moves to the position of the pair of pressing tools (6) (6) Then press
(6) Hold the slab (2) under pressure with (6),
After the (1) and (21) are brought into close contact with each other, the pair of pressing tools (6) and (6) are opened to continue the normal continuous work. In this way, the slab (2) in which the solidified shells (21) (21) facing each other are closely attached, the molten steel in the preceding slab (2) and the following slab (2) of different materials Molten steel
Mixing with (1) is prevented. When the boundary of the slab (2) of the different material is narrowed by the pair of pressing tools (6) and (6), it is desirable that the thickness of the solidified shell is 20 mm or more and 50 mm or less.
If it is less than 20 mm, the solidified shells (21) (21) may be broken at the narrow pressure to cause so-called breakout.
When it exceeds 0 mm, the mixed region in the boundary portion of the different material slab (2) becomes large, and the so-called boundary material, which is a nonconforming portion due to the mixing of different materials, increases and the yield decreases.
The position below the mold where the pressing tools (6) and (6) are provided is adjustable, and the pressing tool (6) is used when the thickness of the solidified shell (21) is at the above-mentioned suitable value according to the casting temperature and the drawing speed. It is desirable that the slab (2) can be narrowed with (6). In the embodiment of the device of the present invention for carrying out the method of the present invention, the pressing tool (6)
Although (6) is a roller, it may have a columnar shape, a trapezoidal shape or a conical shape as shown in FIGS. 2 (a), (b) and (c), and the drive devices (7) and (7) are fluid cylinders. However, a rack and pinion mechanism driven by an electric motor may be used.

Example When performing the multi-continuous casting of the preceding melting charge and the succeeding melting charge of the materials shown in Table 1 into the slab dimensions shown in the table,
The present invention in which a slab is drawn at the casting temperature and the drawing speed shown in the table, and when the solidification thickness of the narrow pressure portion is 30 mm, the boundary portion between the preceding and subsequent melting charges is clamped by the device of the present invention shown in FIG. When a slab is manufactured by the method, when a slab is manufactured by inserting a partition plate at the boundary between the preceding melting charge and the succeeding melting charge under the same conditions as in Tables 1 and 2, and the preceding melting charge When the slab was manufactured without taking measures to prevent the mixing of the molten steel of No. 1 and the molten steel of the subsequent molten charge, the pullout stop time at the time of inserting the partition plate and the cutoff length at the boundary between the preceding molten charge and the subsequent molten charge Table 3 shows the results of the comparison of the defective rates caused by ultrasonic inspection in the pre-dissolution charge. From the results shown in Table 3, when the method of the present invention is carried out using the apparatus of the present invention, there is no pull-down stop time that occurs due to the insertion of the partition plate, and the cut-off length of the boundary portion is when the partition plate is inserted or when melt mixing is prevented. It is shorter than when no countermeasure is taken, and it is understood that the defective rate by ultrasonic inspection in the preceding dissolution charge is significantly smaller than when the partition plate is inserted.

EFFECTS OF THE INVENTION If multi-continuous casting of different materials is performed using the method and apparatus of the present invention, it is not necessary to insert a partition plate so that it is not necessary to temporarily stop the withdrawal of the slab, and the preceding materials of different materials are used. Since the solidified shells facing each other at the boundary between the melt charge and the subsequent melt charge are brought into close contact with each other, the mixing of the molten steel of the preceding molten steel charge and the molten steel of the subsequent molten steel charge can be minimized. The length can be shortened, and the defective rate by ultrasonic inspection generated in the preceding dissolution charge due to the powder entrainment that occurs when the partition plate is inserted is small. Therefore, by carrying out the method of the present invention and using the apparatus of the present invention, it is possible to obtain a remarkable effect that the operation rate and the yield in the multi-continuous casting of different materials can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the device of the present invention for carrying out the method of the present invention, and FIGS. 2 (a), (b) and (c) are other examples of the pressing tool used in the device of the present invention. It is a figure which shows a mode. 1 ... Molten steel, 2 ... Cast piece 21 ... Solidified shell, 3 ... Casting nozzle 4 ... Mold, 5 ... Support roll 6 ... Pressing tool, 7 ... Driving device

Claims (2)

[Claims] 1. A multi-continuous casting method for dissimilar materials, characterized in that when discontinuously casting dissimilar materials, a boundary portion of the dissimilar materials is pressed immediately below the mold to bring solidified shells facing each other into close contact. 2. A multi-continuous casting apparatus made of different materials, wherein a pair of pressing tools for pinching the solidified shell and a drive device for driving the pair of pressing tools are provided in a slab passage directly below the mold.