JPS6027558Y2 - Continuous casting mold - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a mold for a continuous casting device.

In general, for example, a mold used in a continuous casting apparatus is one in which molten metal supplied from an upper tundish is passed through and the molten metal is cooled from four sides to form a solidified shell. They are classified into block format, tubular format, and assembly format depending on their shape.

In both types of molds, by cooling the outer surface of the mold with a high-speed water stream, a solidified shell with an optimal thickness is created to prevent breakout (flow of unsolidified parts of the slab to the outside) of the slab in the next water spray cooling area. The cooling capacity is determined in the form of .

That is, for example, when looking at a tubular mold, as shown in the cross-sectional view in FIG.
1.2771, and the outside thereof is equipped with cooling channels 2 with uniform gaps through which high-speed water flows.

When molten metal is supplied to the mold 1, the molten metal is cooled from 4 sides to form a solidified shell 3, the inside of which forms an unsolidified part 4.
The slab 5 has two solid-liquid layers.

Since the gap t2 of the cooling channel 2 and the wall thickness of the mold 1 are both uniform, the slab 5 has a uniform solidified shell 3 with a substantially uniform thickness on the 4 sides, and is sprayed directly below. Although the slab is drawn out toward a cooling area (not shown), cracks tend to occur in the corner portion 5A of the slab, which often causes breakouts.

Therefore, as shown in the cross-sectional view in FIG. 2, the wall thickness tR at the corner lA' of the mold where the corner part 5A of the slab comes into contact is the minimum, and the wall thickness tR at the center part of the mold face lB' where the mold surface part 5B comes into contact t.

A mold 1' having a regular octagonal outer shape with a maximum of .

This mold 1' is manufactured by machining, and when the cooling channels 2 of the gap cherry are uniform, the solidification shell 3 is promoted at the corner part 5A of the slab where the cooling progresses fastest, and the shape of the solidified shell 3 is In 5B, the type of solidified shell 3 is the latest.

As a result, the solidified shell 3 formed in this manner has a maximum thickness t4 at the slab corner 5A, and a minimum thickness (t4) at the center of the mold surface 5B. The thickness t4 of the solidified shell 3 in the portion 5A is sufficient, and the occurrence of breakout is almost impossible.

However, on the other hand, the mold 1' has a wall thickness t of the mold corner IA'.
Since R is small, the strength of this portion is insufficient, resulting in deformation as shown in the cross-sectional view in FIG. 3.

Such mold deformation not only causes breakout in the slab, but also makes the mold unusable.

This invention also has the above-mentioned points of view, and it is possible to sufficiently increase the thickness of the solidified shell at the heel of the slab.
The present invention provides a continuous casting mold with no risk of deformation from the mold corner.The mold corner has a wall thickness smaller than that of other parts, and this mold corner is hardened to the maximum strength range by work hardening. It is characterized by the fact that it has become very widespread.

Next, the continuous casting mold of this invention will be explained by way of examples with reference to the drawings.

FIG. 4 shows a first embodiment of the continuous casting mold of this invention in a plan view for explaining the strength distribution.

°is.

As shown in the figure, the mold 1'' of this invention is formed into a regular square by drawing from a round copper tube.
The wall thickness tR of the mold corner 1A'' is smaller than any other portion.

Wall thickness t of mold surface part IB".

is uniform throughout the mold, but the wall thickness t of the mold corner IA
It is smaller than R.

In the strength distribution of the mold 1'', the machining rate of the mold corner is maximized when drawing with a die so that the maximum strength region a due to work hardening of the mold corner IA'' is maximized.

Table 1 shows the wall thickness and tensile strength of the mold corner IA'' and the mold surface 1B'' in the continuous casting mold of this invention, as well as the breakout incidence after 100 continuous castings. Indicated.

Table 1 also shows the conventional molds having the cross-sectional shape shown in FIG.

As shown in Table 1, in the mold of this invention,
Since the wall thickness tR of the mold corner IA'' is smaller than that of the mold surface, when molten metal is supplied while the outside of the mold is being cooled by a high-speed water flow, the mold corner IA'' is Since the contacting slab corners cool faster than other parts, the solidified shell of the slab is thicker at the slab corners, and the incidence of breakouts is extremely small.
The mold corner IA" is work hardened by drawing and has the maximum strength region a, so that no deformation occurs during the casting operation.

On the other hand, in the conventional mold shown in FIG. 1, in which the corner portions of the mold and the casting surface have the same wall thickness and strength, the incidence of breakouts at the corner portions of the slab was extremely high.

The mold of this invention of the second embodiment, which is also shown in a plan view for explaining the strength distribution in FIG. 5, is the same as that shown in FIG. Before being machined into a regular octagonal external shape, it is plastically worked by cold forging to work harden the mold corner I A '', and the maximum strength region a is strengthened.

Mold corner I in the mold of this invention formed as a result
Table 2 shows the wall thickness and tensile strength of A'' and mold surface IB', as well as the number of castings until mold deformation occurs in 100 continuous castings, in comparison with the conventional mold shown in Fig. 2. Ta.

As shown in Table 2, the mold of this invention, in which the strength of the mold corner I A '' is made larger than that of the mold face I B '', and the maximum strength range a is extremely strong, has a high strength in 100 continuous castings. In contrast, in a conventional mold in which the strength of the mold corner lA' and the mold face lB' were equal, the mold deformed and became unusable after 30 continuous castings.

The mold of this invention can also be manufactured by forming a round copper pipe into a hollow rectangular shape using the core expansion method.
In this case as well, it goes without saying that the corners of the mold are work-hardened to form the maximum strength region.

As mentioned above, according to the mold of this invention, in which the corners of the mold are made thin and formed in the maximum strength range, it is possible to increase the thickness of the solidified shell at the corners of the slab, thereby preventing the occurrence of breakouts. Since there is no mold deformation attributable to the corners of the mold, practical effects such as long-term use are achieved.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a conventional mold with uniform wall thickness, Fig. 2 is a cross-sectional view of a conventional mold with non-uniform wall thickness, and Fig. 3 is a cross-sectional view showing a modified form of the conventional mold of Fig. 2. FIG. 4 is a plan view showing the first embodiment of the mold of this invention in a state of strength distribution, and FIG. 5 is a plan view showing the second embodiment of the same in a state of strength distribution. In the drawings, 1" 1 nt...Mold of this invention, IA", IA"'...Mold corner, IB"
, IB"'...mold surface, tR...mold corner wall thickness, t...mold surface wall thickness.

Claims (1)

[Scope of utility model registration request] A continuous casting mold in which a wall thickness of a corner part of the mold forming a slab head portion is smaller than that of other parts, characterized in that a maximum strength region by work hardening is formed in the corner part of the mold. Casting mold.