JPS61154735A - Spacer ring of mold for horizontal and continuous casting - Google Patents

Abstract

PURPOSE:To permit the easy mounting of a break ring to a casting mold and to prevent the cracking of a shaft by forming the inside surface of a spacer ring in such a manner that the inside diameter decreases from the position to contact with the break ring toward the break ring in the drawing direction of an ingot. CONSTITUTION:The spacer ring 12 has the inside surface part 12a of the prescribed length l in the drawing direction of the ingot from the position to contact with the break ring 11. The inside surface part 12a is so formed that the inside diameter R thereof is smaller than the inside diameter R0 of the inside surface 10a of the casting mold 10 and decreases gradually toward the ring 11. Since the spacer ring 12 is provided between the mold 10 and the ring 11, the operation to lap the fresh break ring 11 to the spacer ring 12 is executed out of the line to permit the easy mounting of the ring 11. The generation of a crack to a cold shut 17 is obviated.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention completely facilitates the rubbing operation when attaching a break ring to a mold, and also prevents cold shut cracks from occurring in slabs. This article concerns the spacer ring for horizontal continuous casting molds, which is a perfect companion for the market.

[Prior art and its problems]

In a horizontal continuous casting machine, a mold, a secondary cooling zone, and a pinch roll are arranged on a horizontal axis, and the mold is horizontally connected to a tundish. FIG. 3 is a schematic vertical sectional view showing the joint between the continuous casting mold and the tundish.

In FIG. 3, 1 is a horizontal continuous casting mold, and the mold 1 is connected to a tundish 5 via a break ring 2, a supply nozzle 3, and a front nozzle 4. Chrysanthemum type 1 like this
Now, in order to prevent the extremely thin IU hard shell from breaking that occurs near the break ring 2 when the slab is pulled out, and to prevent the mold 1 from seizing, etc., the pattern of pulling and then stopping is periodically set. While repeating, the whole slab is intermittently pulled out from the mold l.

Figure 4 shows the turn of drawing the slab. FIG. In Fig. 4, part a is the drawing stage of the slab, part b is the final stage of drawing, and part C is the stopping stage. In order to prevent this, the entire slab is pushed back slightly. like this/
? Figures 5(a) to 5(c) show how the shell is formed when the slab is completely pulled out in a turn. Figure 5(a) shows the fourth
At the beginning of drawing, which is the beginning of part a in the figure, as shown in Fig. 5(b),
Similarly, FIG. 5(c) corresponds to the final drawing stage of b, and FIG. 5(c) corresponds to the stopping stage of C. The intermittent drawing of the unsolidified slab 6 causes the solidified shelf that is thinly formed in the vicinity of the break ring 2 during drawing to grow thicker as shown in FIG. 5(c) when the unsolidified slab 6 is stopped, and then the unsolidified slab 6 This has the effect of preventing the coagulation/el 7 from breaking when it is pulled out. .

However, from such an unsolidified slab 6, a seam (hereinafter referred to as "cold 7 joint") 8 is formed between the expanded shell and the solidified shell formed during drawing following stopping. As long as this cold 7 kit 8 is completely welded, cold shut cracks will not occur, but if welding is incomplete, cracks will occur, and cracks will appear on the surface of the slab near the cold/kit 8. . Generally, if the drawing cycle is 150 times/M or more, welding is complete and cold/yant cracking can be prevented from occurring. but.

Is it a drawing roll that requires a total of 150 drawing cycles/silk or more? This places a heavy burden on the extraction equipment such as the
:J) In practice, the number of cycles for drawing and drawing is 50 to 150.
It is limited to speeds in the range of revolutions/m2. At this speed, when the drawing is stopped, the break ring 2 of the mold 1
The temperature of the solidification shelf a centered at a point 9 (hereinafter referred to as a triple point) in contact with both the steel and the molten steel drops significantly. Therefore, during subsequent drawing, the molten steel newly flowing into the mold 1 through the break ring 2 was well welded to the solidified shelf a. The solidified shell is not completely formed, and cracks occur in the cold 7 shell.

This triple point 9? How does the central coagulation nonyl 7a decrease with the passage of stop time? , when examining the vicinity of the triple point 9, the result is as shown in Fig. 6. As is clear from Fig. 6, the temperature of the solidified shell near the triple point drops rapidly even after a pause of only 0.1 to 0.3 seconds, and the solidified shell is formed as the center of all triple points. It can be seen that the temperature of the solidified shelf a decreases significantly. According to experience,
When the temperature near this triple point becomes about 1400°C or less, the solidified shelf formed from the inflowing molten steel during the next drawing will not weld well to the shell 7a centered on the triple point, and the cold 7 A part of No. 8 remains on the surface of the slab as a crack. The depth of this crack is usually 0.5 to 165
It is the throat.

On the other hand, it is important that the break ring 2, which ensures the starting point of solidification of molten steel in response to the intermittent drawing of slabs, is attached to the mold 1 so as not to create any gaps. If there is a gap, when the molten steel enters the gap and cools down in steps 1 to t, this causes the slab to get caught during drawing, leading to breakage of the solidification shelf and breakage of the break ring 2. For this reason, each time the break ring 2t is replaced, the outer surface of the new break ring 2 must be adjusted so that there is no gap between the new break ring 2 and the mold 1. After polishing, all the work of rubbing against the new break ring 2vi-mold 1 is done. However, the mold 1 installed in the line
Are you working on the new brake ring 2? Is it a lot of effort? It takes. Furthermore, it is difficult to check whether the new break ring 2 can be rubbed together to ensure that no gap is created between it and the mold 1.

[Purpose of the invention]

This invention was developed in view of the above-mentioned current situation, and was developed in light of the above-mentioned current situation. Is it easy and does cold shut cracking occur in slabs? A spacer ring for horizontal continuous casting molds that completely prevents the problem? The purpose is to provide money.

[Summary of the invention]

The cross ring of the horizontal continuous casting mold of the present invention is provided between the mold and the break ring, which are arranged in series in the horizontal direction. A spacer ring having one end connected to the mold-side surface of the break ring and the other end connected to the inner surface of the mold, wherein the spacer ring has a positional force between the inner surface of the spacer ring and the break ring. It is characterized in that the inner surface portion extending over a predetermined length in the pulling direction is formed such that the inner diameter thereof gradually decreases toward the break ring.

[Structure of the invention]

Hereinafter, the present invention will be described in detail based on drawings of the spacer ring of the horizontal continuous casting mold.

FIG. 1 is a partial vertical sectional view showing a partial metal on the break ring side of a horizontal continuous casting mold. In Figure 1, 10
is the mold, and 11 is the break ring.

12 is a spacer ring of this invention. The spacer ring 12 is provided between the mold 10 and the break ring 11'', and is arranged between the circular surface 10a of the mold 10 and the break ring 11''.
It continues to the inner surface 11a on the mold lo side. Like the mold 1o, the strainer ring 12 is made of copper or a copper alloy, and has a cooling water passage 13 provided therein. Since such a spacer ring 12 is made of metal, it can easily achieve close contact with the mold 1o. Therefore, if a spacer ring 12 is provided between the mold 1o and the break ring 11, each time the break ring 11 is replaced, the spacer ring 12 is removed and a new break ring 12 is placed between the spacer ring 12 outside the line. All you have to do is rub the new brake ring 1 together to avoid any gaps.
1. The spacer ring 12 has an inner surface portion 12a having a predetermined length t in the slab drawing direction from a position in contact with the break ring 11, and the inner surface portion 12a is The inner diameter R thereof is smaller than the inner diameter 2 of the inner surface 10a of the mold 1o, and is formed so as to gradually become smaller toward the break ring 11. The inner diameter Ro of the mold IO corresponds to the outer diameter of the slab to be cast, and in the case of a round slab, 1c represents the diameter, and in the case of a square slab, the length corresponds to one side of the rectangle. .

Therefore, the inner diameter R of the spacer ring 12, like the inner diameter Ro of the mold 10, is used in a meaning corresponding to the cross-sectional shape of the slab.

According to the above, the spacer ring 12 smells and the inner surface part 1
Inner diameter R of 2a? The triple point 14i, where the inner surface portion 12a contacts both the break ring 11 and the molten steel, is made smaller.
This is because the point is located inside the mold IO from the point of the inner surface portion 10a of the mold 10. Triple point 14i inside the mold 10
By locating the triple point 14, the distance between the triple point 14 and the outer surface 15 forming the cooling water passage of the mold 10 becomes greater. Become. Then, when a piece of wire is further pulled out, the solidified shell 16a moves to the right as shown in the figure and is separated from the inner surface 10a of the mold 10 (J), so that the solidified shell 16a is exposed to the incoming molten metal. The melt is reheated and welded well to the solidified shell 16b formed from the melt A. Therefore, although the cold shut 17 is formed at an angle in the solidified shell 16, cracks can be prevented from occurring in the cold shut 17.

Inner surface portion 12 of spacer ring 12 with smaller inner diameter Rt
It is preferable that the length t of a is equal to or less than the length L of the drawing pitch of the slab. This is because if the length t of the inner surface portion 12a is considerably larger than the length of the drawing pitch, the outer diameter of the slab formed at the start of casting will be smaller than the outer diameter of the slab finally formed. This is because when the drawing of the slab starts, leakage occurs in the drawing direction.

In the case of casting steel slabs, the length of the drawing pitch is 5 to 30.
Since it is north of the fan, the length t of the inner surface portion 12a is 5 to 30 mm.
It will be below my range.

Is the inner diameter R of the inner surface portion 12a set to the minimum inner diameter R+ at the inner position of the portion in contact with the break ring 13, and the inner diameter portion 12a is a smooth curved surface? It is determined that the The minimum inner diameter R, is the inner diameter of the inner surface portion 10a of the mold IO (inner diameter corresponding to the slab) Ro, and 21+ = Ro
-Rt is determined so that h is approximately 2 to 1 Oam. In this case, it was mentioned earlier that Ro, R1, and R represent the diameter or one side of a rectangle depending on whether the mold 10 is for a round slab or a square slab, and according to fC6 experience, the minimum inner diameter RL7ll is 2. To make it about ~10 curses,
This is most effective in preventing cracks from occurring in the cold shut 17.

The curved surface of 1% of the inner surface 12a is concave in the outward direction (downward in the plane of the drawing), as is the case with this spacer ring 12;
It may be linear as shown in FIG. 2(a), or may be convex inward as shown in FIG. 2(b).

According to the results of casting square steel slabs or round slabs with cross-sectional dimensions of 80 to 350 mm for carbon steel and various alloy steels,
The curved shape of the inner surface portion 12a of the spacer ring 12 is the first
2(a) and 2(b),
Although we were able to prevent the cold shut from cracking,
It is most effective when it is concave outward, like the mold 10 in FIG.

According to the spacer ring 12 described above, since the triple point 14 of the inner surface 12a of the spacer ring 12 is located inward of the mold 10 than the inner surface 10a of the mold 10, the triple point 14 of the inner surface 12a of the spacer ring 12 is located closer to the inside of the mold than the inner surface 10a of the mold 10. The solidified shell 16a formed around the solidified shell 16a can completely prevent a large temperature drop,
After the subsequent drawing of the slab, the solidified shell 16
3? Since the solidified shell 16a can be prevented from coming into contact with the inner surface portion 12b, the solidified shell 16a easily regenerates heat,
From the molten steel flowing into the mold 101F3 to Kasuri, the shape 111.
It is well welded to the solidified shell 16b. Therefore, although the cold shut 17 is formed within the solidified shell 16, cracking of the cold shut 17 does not occur.

Further, the triple point 1 of the inner surface portion 12a of the spacer ring 12
Although partial melting damage may occur near 4 and a dent may be formed, the inner surface portion 12a becomes narrower as it goes toward the break ring 13, and the resistance to pulling out the slab is small, so the dent is formed. The solidified shell will not break even if

〔Effect of the invention〕

Since the spacer ring of the horizontal continuous casting mold of the present invention is constructed as described above, it is possible to prevent cold 7 cast cracks from occurring in the slab. Furthermore, since the cold shut is inclined with respect to the surface of the slab, it can be easily eliminated by crushing during rolling. Moreover,
By providing this sparing, the rubbing work when installing the brake ring becomes much easier.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the spacer ring of the present invention provided between the break ring and the horizontal continuous casting mold;
Figures 2 (a) and (b) are longitudinal sectional views showing other examples of the curved shape of the circular portion of the spacer ring of the present invention with a reduced inner diameter, and Figure 3 shows the joint between the mold and the tundish. The longitudinal cross-sectional view shown in Figure 4 shows the drawing and turfing of slabs? The figures shown in Figures 5 (a) to (c) show how the shell is formed in the mold. The figure shown in FIG. 6 is a graph showing the temperature of the shell near the triple point of the mold. In the drawings, 10... Mold, 10a... Inner surface of mold, 11... Break ring, lla... Inner surface of break ring, 12... Spacer ring, 12a... Inner surface portion of spacer ring, 13...Cooling water passage, 14...Triple point, 16.16a,
16b--solidified shell. 17...Cold 7 guy.

Claims (2)

[Claims] (1) A spacer ring provided between a mold and a break ring that are arranged in series in the horizontal direction, one end of which is connected to the surface of the break ring on the mold side, and the other end of which is connected to the inner surface of the mold. , an inner surface portion of the spacer ring extending over a predetermined length in the slab drawing direction from a position in contact with the break ring is formed such that the inner diameter gradually decreases toward the break ring. A spacer ring for horizontal continuous casting molds. (2) A patent characterized in that the length of the inner surface portion, which is formed so that the inner diameter gradually decreases toward the break ring, is equal to or less than the length of the drawing pitch of the slab to be drawn from the mold. A spacer ring for a horizontal continuous casting mold according to claim 1.