JPH01166862A - Roll mold in twin roll type continuous casting machine - Google Patents

Abstract

PURPOSE:To stably obtain a cast slab having only a little unevenness of the thickness by sticking a material having heat conductivity lower than copper to the whole round of outer peripheral surface of outer cylindrical part of copper-made roll-mold at more than thickness having the value of the specific times to the value of the heat conductivity. CONSTITUTION:Molten metal 3 in a tundish 4 is poured into a pouring basin between two cooling rolls 1 and side weirs 2 through a core 5 and cooled with rotation of the cooling rolls 1 to form solidified shell 8 and the cast strip 9 is continuously cast. Over the whole periphery of the outer peripheral surface 11 at outer part 10 of the cooling roll (copper-made roll-mold) 1, the material 11 of nickel series, etc., having heat conductivity lower than the copper is stuck with plating or thermal spraying. This is stuck at thickness value (mm) more than about 10 times of the value (cal/cm.sec.deg) of the thermal conductivity. By this method, the cast strip having only a little unevenness of the thickness can be stably and continuously produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a roll mold for a twin-roll continuous casting machine that directly produces thin plates from molten metal.

[Prior art] A continuous casting machine (continuous casting machine) produces slabs, billets, etc. by pouring molten metal (molten metal) such as steel from a tundish into a water-cooled mold to form slabs and drawing them out under pressure with multiple rolls. It is generally well known that the manufactured slab or billet is cut into a certain length, sent to a rolling process via a heating furnace, and finished into a strip (thin plate) or the like. In order to further streamline the equipment of continuous casting machines for producing slabs and billets, a so-called twin-roll continuous casting machine has been developed for producing thin plates directly from molten metal.

Fig. 4 shows an explanatory diagram of the basic structure of a twin-roll continuous casting machine.

Two cooling rolls (roll molds) are provided substantially horizontally and parallelly with an interval between them, and side weirs 2 are arranged at both ends in the width direction. And the cooling roll (roll mold)
Tundish 4 for injecting molten metal 3 above ■
and a core 5 is provided at the bottom thereof, and an injection port 6 for the molten metal 3 is provided in the tundish 4 and the core 5. A pool 7 is formed by the two cooling rolls 1 and the side weirs 2 at both ends in the width direction. The lower end of the core 5 is submerged in the hot water pool, and the injection port 8 opens toward approximately the middle of the distance between the centers of two cooling rolls (roll molds). .

When the molten metal 3 is injected from the tundish 4 through the inlet 6, two cooling rolls l and side weirs 2 at both ends of the molten metal 3 are injected.
A molten metal pool 7 is formed between the molten metal 3 and the molten metal 3 in the molten metal pool 7. The molten metal 3 in the molten metal 3 is cooled by a cooling roll (roll mold) 1 to form a solidified shell 8, and as the cooling roll 1 rotates in the direction of the arrow, a thin plate-like casting is formed. Pieces 9 are successively cast.

The two cooling rolls 1 have an outer cylindrical portion 10 made of a copper-based material with good thermal conductivity, and a cooling medium is circulated through the inner surface of the outer cylindrical portion 10. By cooling the molten metal 3 in the pool 7 to form a solidified shell 8 and shaping a thin slab 9, it functions as a roll mold.

[Problems to be solved by the invention] However, as mentioned above, the roll mold made up of the cooling roll uses a copper-based material with good thermal conductivity for its outer cylindrical part, so it is difficult to make contact with it. The molten metal is rapidly cooled, and as a result, uneven thickness occurs on the surface of the thin slab that is cast. As mentioned above, the feature of the twin-roll continuous casting machine is that it continuously casts thin sheets directly from the molten metal.Moreover, it minimizes the unevenness of the thickness of the cast thin sheets and produces high-quality surfaces. Must.

In reality, the thickness of the slab to be cast is about several ml11, but if a conventional roll mold made of copper-based material is used, the thickness of the slab is several tens of millimeters thick.
At present, thickness unevenness of 0 μm occurs.

The present invention provides a roll mold for a twin-roll continuous casting machine that improves the surface precision of the cast slab by attaching a material with lower thermal conductivity to the outer peripheral surface of the copper roll mold. The purpose is to

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned circumstances, and uses two cooling rolls arranged horizontally and parallel to each other and side weirs arranged at both ends of the cooling rolls. In a twin-roll continuous casting machine that forms a pool, the cooling roll constitutes a roll mold, and the molten metal in the pool is cast into a thin slab by rotation of the roll mold, the outer cylindrical part of the copper roll mold. A material whose thermal conductivity is lower than that of copper is placed around the entire outer circumferential surface of the
The film is characterized in that it is deposited with a thickness equal to or greater than the value (millimeters) approximately 10 times larger than eg).

[Function] When continuously producing thin slabs while cooling the molten metal in the pool housed on the roll mold by the rotation of the roll mold, the entire outer peripheral surface of the outer cylindrical part of the copper roll mold is Because a nickel-based material or chromium-based material, etc., which has a lower thermal conductivity than copper, is attached to the periphery with an effective thickness, the cooling rate of the molten metal becomes slow, resulting in an unrestricted thickness of the manufactured thin plate. Thickness unevenness is greatly reduced. In addition, nickel-based or chromium-based materials have high heat resistance, so stable casting operations are guaranteed.

[Implementation example] Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in Figure 1, cooling roll (copper roll mold)■
Plating a nickel-based or chromium-based material 11 having a lower thermal conductivity than copper over the entire circumference of the outer peripheral surface 11 of the outer cylinder portion 10,
Attach by thermal spraying, etc. The thermal conductivity of copper, which constitutes the outer cylinder portion IO, is approximately 0.99 cal/cm −5 at room temperature.
ee -deg, whereas for nickel it is about 0.
20cal/am 6 sec @deg.

Chromium is approximately 0.16 cal/cffl-8ec-deg
It is.

According to the experimental results, the thickness unevenness of the cast piece 9 to be cast with respect to the thickness of the nickel layer attached to the outer circumferential surface 11 of the outer cylinder part 10 is shown as shown in FIG. In the vicinity where the nickel layer thickness is close to zero, the unrestricted thickness unevenness of the slab is 10
However, as the nickel layer thickness increases, the thickness unevenness decreases, and the thickness unevenness decreases markedly when the nickel layer thickness is about 2111 m, and then it shows a tendency to gradually decrease. It can be seen that adhesion with a thickness of 2 mm or more is effective in reducing unrestricted thickness unevenness. In addition, thermal conductivity is dimensionally proportional to the length (thickness) (cm) through which heat is conducted from the dimension of thermal conductivity, and the relationship between effective adhesion layer and thermal conductivity is It can be expressed as shown in FIG. According to this Figure 3, if the effective adhesion layer thickness is 2ml11 for the thermal conductivity of nickel of 0.20callcIIl-8eC-deg, then it is 1.8mm for the thermal conductivity of chromium of 0.16ca11clll-8eC-deg. Become.

Therefore, the unrestricted thickness unevenness of the thin plate slab to be cast is determined by using a material such as a nickel-based material or a chromium-based material, which has a thermal conductivity lower than that of copper, at its thermal conductivity value (Ca1/CmCm-8
By attaching eC-de to the outer circumferential surface of the roll mold at a thickness approximately 10 times greater (in millimeters), it can be greatly reduced, and these materials also have higher heat resistance than copper-based materials. The high cost makes stable casting operations possible.

[Effects of the Invention] According to the present invention, it is possible to achieve an excellent effect of being able to stably and continuously manufacture thin plate-shaped slabs with little thickness unevenness.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of an embodiment of the present invention, Figure 2 is a diagram of the relationship between nickel layer thickness and unrestricted thickness unevenness of the slab, and Figure 3 is a diagram of the relationship between thermal conductivity and effective adhesion layer thickness. , FIG. 4 shows an explanatory diagram of the principle structure of a twin-roll continuous casting machine. In the figure, 1 is a cooling roll (roll mold), 2 is a side weir, and 7
1 is a molten metal pool, 9 is a thin slab, 10 is an outer cylinder, and 11 is a nickel-based or chromium-based material. Nibuke 1 Shiman 3 (mm) Figure 3 Figure 4

Claims (1)

[Claims] 1) A molten metal pool is formed by two cooling rolls arranged horizontally and in parallel and side weirs placed at both ends of the cooling rolls, and the cooling rolls constitute a roll mold, and the molten metal in the molten metal pool is In a twin-roll continuous casting machine that casts thin slabs by rotating a roll mold, a material with a lower thermal conductivity than copper is applied to the entire outer circumference of the outer cylindrical part of the copper roll mold. value (cal/cm・s
A roll mold for a twin-roll continuous casting machine, characterized in that the mold is deposited to a thickness equal to or more than approximately 10 times the value (e.g., ec/deg) (in millimeters).