JP2993868B2 - Continuous casting mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting mold. More specifically, the present invention relates to a mold for continuously casting square slabs having a rectangular cross section.

[0002]

2. Description of the Related Art When continuously casting steel using a bottomless mold having open upper and lower ends, a solidified shell develops as the poured molten steel is cooled, but at this time, the slab itself shrinks. In addition, a gap is easily generated between the mold and the mold wall. When the gap occurs, the heat conduction between the mold and the slab solidified shell is significantly reduced, the cooling of the slab becomes uneven,
Quality defects such as rhombic deformation, cracks, and poor structure occur. In order to solve such a problem, a single taper tapering from the upper end to the lower end was conventionally provided on the inner surface of the mold wall, but thereafter, in order to increase the casting speed, multiple stages corresponding to the solidification stage were performed. A taper (gradient taper rate gradually decreasing toward the downstream side from the molten steel surface)
No. 51803) has been proposed. In recent years, a modified cross-section mold has been proposed for the purpose of further increasing the casting speed and preventing slab breakage and breakout,
As such modified cross-section molds, there are molds described in JP-A-4-319044 and U.S. Pat. No. 4,207,941. In the mold described in Japanese Patent Application Laid-Open No. Hei 4-319044, in the upper half of the mold, a substantially central portion of all four sides constituting the cross-sectional contour of the mold wall is curved and extended to form an overhang portion. The amount of overhang is reduced downward, and the cavity is formed in a substantially square shape in the lower half of the mold. The mold described in U.S. Pat. No. 4,207,941 has a square shape with a trough at the upper end of the mold, a tapered middle portion, and an octagonal corner at the lower end. Are formed in irregular dodecagons.

[0003]

However, the above-mentioned conventional mold having a modified cross section has a problem that it takes a lot of man-hours to process and mold a mold wall (also referred to as a tube) and the production cost is high. Further, the following problems cannot be solved by the above-mentioned conventional mold. That is, when casting a small slab with the curved continuous casting machine shown in FIG. 6 , the curved radius R is small, and the curved radius outer wall surface (hereinafter, referred to as R outer surface) and the curved radius inner wall surface (hereinafter, referred to as R outer surface) of the mold M. , R
(Referred to as the inner surface), a difference easily occurs in the slab cooling conditions. This is because the injection flow from the tundish T may re-melt the solidified shell on the outer surface of the R in the mold M or cause a delay in the formation of the solidified shell, and further, the continuous casting to produce a plurality of slab sizes. This is because the slab may be displaced in the direction of the R inner surface as often observed in a mold without a machine or a foot roll. If the cooling conditions are different between the R inner surface and the R outer surface of the slab, the thickness of the solidified shell becomes non-uniform, which also lowers the slab quality and causes accidents such as breakout.

[0004] In view of the above-mentioned circumstances, an object of the present invention is to provide a continuous casting mold that can be easily processed and formed and can reduce the manufacturing cost. Another object of the present invention is to provide a continuous casting mold that can finely adjust the heat removal inside and outside the R even in a continuous casting mold having a small radius of curvature, and can make the solidified shell thickness uniform around the entire slab. And

[0005]

According to the first aspect of the present invention, the upper end
The lower end is open and has a cylindrical cavity.
Casting with a taper that tapers toward the bottom
Mold, wherein four sides constituting a cross-sectional profile of the mold wall are provided.
Of the two sides orthogonal to the reference side outside the radius of curvature
Form a compensating surface and do not form a shrinkage compensation surface on the remaining sides
It is characterized by straight sides . The invention of claim 2, upper
Open end and bottom, have a cylindrical cavity, top end
Continuous casting with a taper that tapers from the bottom to the bottom
A molding mold, wherein the cross-sectional contour of the mold wall is 4
Of the sides, shrink to the long side opposite the reference side outside the radius of curvature
Form a compensation surface and do not form a shrinkage compensation surface on the remaining sides.
It is characterized by having straight sides . The invention of claim 3 is
The upper and lower ends are open and have a cylindrical cavity.
Continuous tapered from end to bottom
A casting mold, comprising a cross-sectional profile of the mold wall.
Of the four sides, shrinkage compensation is performed on three sides except the reference side outside the radius of curvature.
Form a compensating surface and do not form a shrinkage compensation surface on the remaining sides
It is characterized by straight sides . Note that, in the present invention, the shrinkage compensation curved surface refers to whether the central portion of each side is bulged outward so as to compensate for the shrinkage of the slab on the four sides of the mold, or whether both ends of each side are moved inward. 5 is a portion where the groove depth (δ) is adjusted by the constant curvature processing. The shrinkage compensation rate refers to the rate of change in the length of the contour of the mold piece in the vertical direction of the mold, and as described with reference to FIG. 4 , on the curved surface side, (S1−S2) / (S1 · Δh). On the straight side, it is expressed by (d 1 −d 2) / (d 1 Δh). In addition, on the straight side, it agrees with the taper amount. Further, the term "constant curvature processing side" refers to a side having the same curved surface radius in the vertical direction of the mold and easy processing even if it is a curved surface side.

[0006]

According to the first to third aspects of the present invention, the shrinkage compensation curved surface is formed on some of the four sides constituting the cross-sectional profile of the mold wall. Even if the shrinkage compensation curved surface is not formed, even a part of the shrinkage compensation curved surface can compensate for the shrinkage of the slab so that no gap is formed between the slab and the mold wall. According to the first to third aspects of the present invention, some of the sides are straight sides, so that the mold wall can be easily manufactured and maintained .

[0007]

Next, embodiments of the present invention will be described with reference to the drawings . FIG. 1 (a) shows a mold M according to an embodiment of the present invention .
1 is a longitudinal front view, (b) is a longitudinal side view, (c) is a plan view, (d) is a bottom view, and FIG. 2 is a plan view of a mold M2 according to an embodiment of the present invention . FIG. 3 is a plan view of a mold M3 according to an embodiment of the present invention .

[0008] The template M1 according to the embodiment of the first aspect of the present invention.
As shown in FIG. 1, shrinkage compensation curved surfaces are formed on two opposite sides of the mold walls 1 to 4. In the illustrated example, the reference side 1 of the R outer surface and the free side 2 of the R inner surface (the reference side 1 and the free side 2)
Is usually a long side, and hereafter, it is a straight side obtained by adding only the taper T to the long sides 1 and 2. Both sides 3 and 4 (both sides 3 and 4 are usually short sides. Sides 3 and 4) form a shrinkage compensation curved surface C. The contraction compensation curved surface C is formed by bulging the center of each side outward, or bringing both ends of each side inward. And
The shrinkage compensation area L in which the shrinkage compensation curved surface C is formed is formed halfway from the upper end to the lower end of the mold. Both the contraction compensation amount by the taper T and the contraction compensation amount by the contraction compensation curved surface C decrease from the upper end to the lower end of the contraction compensation region L. Since the shrinkage compensation curved surface is not formed at the lower end of the mold M1, each of the sides 1 to 4 is a straight side. In the mold of the present embodiment, the taper T of the long sides 1 and 2 and the shrinkage compensation curved surface C of the short sides 3 and 4 prevent the mold wall from following the shrinkage due to the solidification of the slab so that no gap is generated. However, since the long sides 1 and 2 are straight sides, processing is easy and maintenance is easy. For example, as compared with the case where the shrinkage compensation curved surface C is machined over the entire circumference, the NC tape making cost is about 1/3 and the machining cost of the tool is about 1/2 or less.

The mold M2 of the embodiment according to the second aspect of the present invention.
As shown in FIG. 2, a shrinkage compensation curved surface C is formed on a long side 2 which is a free side . The mold M3 of the embodiment according to the third aspect of the present invention forms the shrinkage compensation curved surface C on two sides on the non-curved side and one side of the two sides on the curved side. The shrinkage compensation curved surface C is formed on both the short sides 3 and 4 and the long side 2 on the free side. In each of the above two to three examples,
In each case, since the straight sides are left for 1 to 3 sides, it is easy to form the mold wall.

(Other Embodiments of the Inventions of Claims 1 to 3 ) Another example of the shrinkage compensation curved surface C in each of the above embodiments is a fixed curvature processing side. As shown in FIG. 5 , even if the cross-sectional shape of each side is a curved surface,
This means that the curvature radius ρ is the same at any of the upper and lower levels. In this case, in order to reduce the depth δ of the curved surface downward while keeping the radius ρ the same, the processing may be performed while moving the center of the radius ρ downward and away from the wall surface. Thus, if the radius ρ is the same, the processing can be easily performed according to the straight side .

[0011]

According to the present invention, it is possible to provide a continuous casting mold that is easy to process and mold, has low manufacturing costs, and is easy to maintain .

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory views of a first embodiment of the first invention, wherein FIG. 1A is a vertical sectional front view of a mold M1 of the first embodiment, FIG. 1B is a vertical sectional side view, and FIG. The plan view and (d) are bottom views.

FIG. 2 is a plan view of a mold M2 according to a second embodiment of the first invention.

FIG. 3 is a plan view of a mold M3 according to a third embodiment of the first invention.

FIG. 4 is an explanatory diagram of a definition of a contraction compensation rate.

5A and 5B are explanatory diagrams of a fixed curvature processing side, in which FIG. 5A is an explanatory diagram in a case where the side is formed at the center of each side, and FIG. FIG.

FIG. 6 is an explanatory diagram of a problem of a continuous casting mold having a small radius of curvature.

[Explanation of symbols]

1 reference side (long side) 2 free side (long side) 3 both sides (short side) 4 both sides (short side) T taper C shrinkage compensation curved surface L, L1, L2 shrinkage compensation area M1 mold M2 mold M3 mold

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-319044 (JP, A) JP-A-64-31557 (JP, A) JP-A-6-344084 (JP, A) 14687 (JP, B2) Jiko 3-21803 (JP, Y2) Table 7-503410 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 11/04 311

Claims (3)

(57) [Claims] 1. A continuous casting mold having a cylindrical cavity having an open upper end and a lower end, and having a tapered shape tapering from an upper end to a lower end. Of the four sides to be formed, a contraction compensation curved surface is formed on two sides perpendicular to the reference side outside the radius of curvature,
A mold for continuous casting, wherein the remaining sides are straight sides that do not form a shrinkage compensation curved surface. 2. A cylindrical cavity having an open upper end and a lower end.
With a taper that tapers from the upper end to the lower end.
A given continuous casting mold, wherein, of the four sides constituting the cross-sectional profile of the mold wall, the radius of curvature is
Form a shrinkage compensation curved surface on the long side opposite to the outer reference side,
A mold for continuous casting, wherein the remaining sides are straight sides that do not form a shrinkage compensation curved surface . 3. A cylindrical cavity whose upper and lower ends are open.
With a taper that tapers from the upper end to the lower end.
A given continuous casting mold, wherein, of the four sides constituting the cross-sectional profile of the mold wall, the radius of curvature is
Form a shrinkage compensation surface on three sides excluding the outer reference side,
Wherein the side is a straight side that does not form a shrinkage compensation curved surface .