JPH07100601A - Method for fit-sealing dummy bar to continuous casting mold and method for starting casting in continuous casting and dummy bar - Google Patents

Abstract

PURPOSE:To make the change of size and shape of a dummy bar head the unnecessity even in the case of changing the size of a cast slab in continuous casting and make a seal between a mold and the dummy bar head always the constant and the min length. CONSTITUTION:A V-shaped space 5 in the side surface view is formed in the continuous casting mold M by mutually approaching the lower parts of one pair of short side copper plates 2 and the tip end part of the dummy bar head 6 is arranged at the lowermost part of this V-shaped space. Successively, after sealing the gap between the dummy bar head 6 and the short side copper plates 2 with a seal material 13 at the interval of one pair of the short side copper plates 2, molten steel is poured into the V-shaped space 5. At the time of forming the solidified shell S, the one pair of the short side copper plates 2 are widened so as to mutually leave this upper plates far and the pulling-out of the dummy bar 10 is started while shifting to-the stationary casting condition. Even in the case of changing the size of the cast slab, the starting of the casting can do with one kind of the dummy bar and seal the gap between the lowermost parts having the constant length of the V-shaped short side copper plates 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting and sealing a dummy bar in a continuous casting mold at the start of continuous casting, a method for starting casting in continuous casting, and a dummy bar used in these methods.

[0002]

2. Description of the Related Art At the start of continuous casting, a dummy bar head is generally inserted in the lower part of a bottomless mold to form a temporary bottom, and molten steel is cast into such a mold from a dipping nozzle. When the solidified shell having a predetermined thickness is formed in the molten steel and the risk of breakout disappears, the dummy bar is gradually pulled out, and then the casting speed is increased to shift to the steady casting state.

When a dummy bar is inserted and mounted in this mold, there is a gap between the mold and the dummy bar head, so it is necessary to seal this gap with a sealing material to prevent steel leakage and the like. Becomes

Regarding the mounting seal of this dummy bar,
Various proposals have been made, for example, a sealing material having a wedge-shaped cross section and made of metal fibers or the like, or a sealing material that opens outwards upward is attached to the upper side surface of the dummy bar head to seal between the inner surface of the mold and the upper side surface of the dummy bar head. Method (Japanese Patent Application No. 2-1543, Japanese Patent Application No. 4-71757, etc.), a sealing material is previously attached to the upper side surface of the dummy bar, and the dummy bar is placed in a mold set wider than the steady casting state. After the insertion, there is a mounting method (Japanese Patent Application No. 4-71757) in which the long side copper plate and the short side copper plate of the mold are moved so that the mutual intervals are narrowed.

[0005]

However, in any of the conventional dummy bars and the mounting and sealing methods described above, the dummy bar head has a size as close to the mold size as possible within the range in which the dummy bar head can be inserted into the mold, or the mold size. Assuming that the head width is adjusted to a size close to the above, it is necessary to change the size of the dummy bar head in accordance with the change of the slab size, that is, the mold size. Needs to be replaced with a dummy bar head corresponding to the mold size or the width of the dummy bar head needs to be changed.

Further, when a device for automatically adjusting the width of the dummy bar head is incorporated in the dummy bar head, a top insertion method for improving the productivity in recent years (when the rear end of the cast slab of the previous casting leaves the mold) , The dummy bar can be inserted immediately from the top of the mold.) Since the dummy bar is configured by connecting separate and independent unit blocks in a bendable manner, energy supply to the automatic adjustment device and transmission of head width information signal Is difficult.

Further, in the method of filling the seal material in the gap between the mold and the dummy bar head, since the seal material is provided on the four circumferences of the dummy bar, it takes a long time to perform the sealing work, and when the cross-sectional area of the mold becomes large, the seal length becomes long. Become longer,
The frequency of poor sealing tends to increase.

The present invention has been made to solve the above-mentioned problems, and its purpose is not to change the size of the dummy bar head even if the size of the slab is changed, and the mold and the dummy bar. (EN) A sealing method for attaching a dummy bar to a continuous casting mold, which can keep the head-to-head seal constant and the minimum length even if the slab size changes, a casting start method in continuous casting, and the dummy bar.

[0009]

The present invention overcomes the common sense that the mold at the start of casting must be set in the same manner as in the steady casting state, and makes the mold at the start of casting different in shape. Therefore, the above-mentioned problems are solved.

Specifically, when performing casting with a continuous casting mold provided with a pair of movable mold plates (for example, a pair of short-side copper plates) that can move back and forth, the lower parts of the pair of movable mold plates are By making them close to each other, a V-shaped space in a side view is formed in the continuous casting mold, and the tip end portion of the dummy bar head is arranged in the lower apex portion of the V-shaped space, and then the pair of movable mold plates. The lower end portion of the sheet and the dummy bar head and the movable mold plate are sealed with a sealing material. Further, when the sealing is completed, molten metal is injected into the V-shaped space, and when a solidified shell is formed in the molten metal, the pair of movable mold plates are spread so that their lower portions are distant from each other so as to be steady. While shifting to the casting state, pulling out the dummy bar is started.

The dummy bar includes a rod, a dummy bar head connected to a molten metal solidified shell in the continuous casting mold at the start of casting, and a molten metal solidified shell in the continuous casting mold provided at one end of the rod. It is composed of a locking portion such as a horizontal disk which can be integrated, and a connecting portion such as a hook which is provided at the other end of the rod and is detachably attached to the dummy bar main body.

[0012]

With the above construction, even if the slab size (slab width), that is, the mold size is changed, the dummy bar head is arranged at the lower apex portion of the V-shaped space, so that the size and shape are always the same. Different types of dummy bar heads can be used.

Further, since the sealing material may be filled in the ridge line portion at the lower apex portion of the V-shaped space, the sealing length can always be kept constant and the minimum length even if the slab size changes. It is possible to shorten the sealing work time and reduce sealing defects.

The dummy bar head may have a locking portion and a connecting portion formed at both ends of the rod, and can have a small size and a simple structure.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an illustrated embodiment. This is an example of use in a continuous casting mold in which a pair of short side copper plates sandwiched by a pair of long side copper plates advance and retreat with respect to each other to make the width of a slab variable.

As shown in FIG. 2, the continuous casting mold M is constructed by arranging a pair of short side copper plates 2 and 2 between a pair of long side copper plates 1 and 1, and injecting molten steel by a dipping nozzle. It A back frame 3 is attached to the back surface of each of the copper plates 1 and 2, and a cooling water passage is provided between the copper plate and the back frame.

On the back surface of the back frame 3 of the short-sided copper plates 2 and 2, a pair of linear driving devices (a hydraulic cylinder or a screw rod rotatably driven by a motor) are respectively arranged vertically.
4 and 4 are connected, and by operating the linear drive units 4 and 4, the short side copper plates 2 and 2 come close to each other.
By moving in parallel to the separating direction to change the width of the slab and operating the lower linear drive mechanism 4, a taper that narrows downward according to the solidification shrinkage amount of the slab is provided. There is.

According to the present invention, even if the width of the slab is changed, a dummy bar head having the same size and shape can always be used in the mold M, and the seal between the mold and the dummy bar head is always constant and has a minimum length. It can be so. Therefore, as shown in FIGS. 1 and 2, at the start of casting, the pair of short-side copper plates 2 and 2 are V-shaped in a side view from the long-side copper plate side to form a V-shaped space 5 in the mold M. At the same time, the upper portion of the dummy bar head 6 as shown in FIG. 3 is arranged in the lower vertex portion of the V-shaped space 5.

The length of the short side copper plate 2 in the casting direction is the same as the length of the long side copper plate 1 in the casting direction in the case of a normal mold, but the V-shaped space 5 formed when the width of the cast piece is large. When the height in the casting direction cannot be sufficiently obtained, it may be formed to be larger than the length in the casting direction of the long side copper plate 1. Further, the upper end of the short side copper plate 2 is set in a steady casting state corresponding to the width of the cast piece, and the V-shaped space 5 is formed by moving only the lower portion, but from the position corresponding to the width of the cast piece to the upper portion. It is also possible to move both the lower part and the lower part to form the V-shaped space 5.

The dummy bar head 6 may be a simple metal article in which a horizontal disk 8 as a locking portion is integrally formed on an upper portion of a rod 7 and a hook 9 as a connecting portion is integrally formed on a lower portion thereof, and is a disposable consumable item. The outer diameter of the horizontal disk 8 is larger than the diameter of the rod 7, and the horizontal disk 8 is integrally engaged with and fixed to the solidified shell S of molten steel so as to sufficiently withstand the pulling force.

The dummy bar 10 includes a large number of unit blocks 1
0a is connected via a pin or the like to allow bending,
A hook 11 for hooking the hook 9 is attached to the upper unit block 10a. This allows the dummy bar head 6 and the dummy bar 10 to be easily attached and detached.

As shown in FIG. 4, a pair of short-sided copper plates 2 are formed in a semicircular cutout shape in a plan view in a V-shape at the center of the lower end surface of the short-sided copper plates 2 and 2 in the thickness direction of the cast piece. Each of the holes 12 is formed so that a substantially vertical hole is formed in a state where the lower end portions of the short-side copper plates 2 are in contact with each other, and the rod 7 is arranged in this hole with a margin.

With the above structure, continuous casting is performed as follows (see FIG. 1).

(1) At the start of casting, a pair of short side copper plates 2 and 2 are paired with a pair of long side copper plates 1 and 2 in accordance with the width of a cast piece to be cast.
1 are positioned in parallel with each other, and the dummy bar 10
Is inserted into the slab support roll group forming the secondary cooling zone from above the mold M or from below the mold M.

(2) The dummy bar 10 is arranged so that its upper portion is located directly below the mold M. The dummy bar head 6 is attached to the dummy bar 10 and the horizontal disk 8 thereof is immersed in the immersion nozzle N.
Is held by a suitable method so that the rod 7 is located below the lower end of the pair of short side copper plates 2 and 2.

(3) The lower parts of the pair of short-side copper plates 2 and 2 are moved in a direction in which they approach each other by the linear driving mechanism 4 of the lower parts while keeping the upper end position of the set slab width. The short side copper plates 2 and 2 are V-shaped.

(4) A pair of V-shaped short side copper plates 2, 2
A sealing material 13 is filled between the lower end portions of the above and the gap between the rod 7 and the oblique hole 12.

(5) Molten steel is injected into the V-shaped space 5 formed in the mold M from the immersion nozzle N, and casting is started.

(6) When the solidified shell S is generated, the dummy bar is started to be pulled out, and at the same time, the pair of short side copper plates 2,
The lower part of 2 is gradually widened, and the short-side copper plate 2 is placed in parallel in a steady casting state.

Thereafter, a cast piece is manufactured by increasing the casting speed and by the usual continuous casting method. The dummy bar 10 can be easily removed from the tip of the slab. The tip end of the slab becomes a triangular prismatic variant with the dummy bar head 6, but by adjusting the casting time (short side copper plate moving time) of this variant within the range where breakout does not occur,
The deformed part can be suppressed within the range of normal scrap down, and there is no actual damage.

Even if the width of the slab is changed, the V-shaped space 5 can use the dummy bar head 6 of the same size and shape only by changing the inclination angles of the pair of short-sided copper plates 2 and 2. Just prepare a head.

Further, the filling length of the sealing material 13 can be always constant and the minimum length even if the width of the slab is changed. FIG. 5 is a graph comparing the mold sealing time between the present invention and the conventional method, and it was possible to significantly reduce the sealing work time. Further, since the sealing portion is short, the frequency of steel leakage due to defective sealing was halved as shown in FIG.

The continuous casting mold in which the pair of short-side copper plates are movable between the pair of long-side copper plates has been described above. However, the present invention is not limited to this. For example, the pair of long-side copper plates can be moved between the pair of short-side copper plates. It goes without saying that the present invention can be applied to various continuous casting molds.

[0034]

As described above, the present invention forms the V-shaped space in the mold by moving the lower parts of the pair of movable mold plates toward each other at the start of casting, and After placing the tip of the dummy bar head in the lower apex part and then sealing the lower apex part, the pair of movable mold plates were opened to move to the steady casting state and the dummy bar was pulled out, so that the following effects Play.

(1) Even if the slab size is changed, a dummy bar having the same size can be used. Every time the slab size is changed, a dummy bar head corresponding to the slab size is replaced or a dummy bar head The work of adjusting the width can be eliminated, and the preparation work can be simplified.

(2) The length of the seal between the mold and the dummy bar head can always be kept constant and at the minimum length, the sealing work time can be greatly shortened, and accidents such as leakage steel due to poor sealing can be greatly reduced. it can.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing in sequence a method of mounting and sealing a dummy bar on a continuous casting mold and a method of starting pouring according to the present invention.

FIG. 2 is a perspective view showing an example of a mold used for carrying out the present invention.

FIG. 3 is a perspective view showing a dummy bar head according to the present invention.

4 (a) is a sectional view and FIG. 4 (b) is a perspective view showing the lower part of the short side copper plate of the mold of FIG.

FIG. 5 is a graph comparing the mold sealing time between the conventional method and the present invention.

FIG. 6 is a graph comparing a seal failure trouble index between a conventional method and the present invention.

[Explanation of symbols]

 M Continuous casting mold N Immersion nozzle 1 Long side copper plate 2 Short side copper plate 3 Back frame 4 Linear drive device 5 V-shaped space 6 Dummy bar head 7 Rod 8 Horizontal disk 9 Hook 10 Dummy bar 10a Unit block 11 Hook 12 Diagonal hole 13 Seal Material

Claims (3)

[Claims] 1. When casting is performed by a continuous casting mold including a pair of movable mold plates that can move back and forth, the lower parts of the pair of movable mold plates are brought closer to each other to provide a side view into the continuous casting mold. To form a V-shaped space, the tip of the dummy bar head is arranged in the lower vertex portion of the V-shaped space, and then between the lower ends of the pair of movable mold plates and between the dummy bar head and the movable mold plate. A method for mounting a dummy bar on a continuous casting mold, characterized in that the space between the two is sealed with a sealing material. 2. When casting is performed by a continuous casting mold having a pair of movable mold plates that can move back and forth with each other, the lower parts of the pair of movable mold plates are brought close to each other so that a side view is formed inside the continuous casting mold. To form a V-shaped space, the tip of the dummy bar head is arranged in the lower vertex portion of the V-shaped space, and then between the lower ends of the pair of movable mold plates and between the dummy bar head and the movable mold plate. After sealing the space with a sealing material,
When the molten metal is injected into the character-shaped space and the solidified shell is formed in the molten metal, the pair of movable mold plates are expanded so that their lower portions are distant from each other to shift to the steady casting state, and the dummy bar A method of starting casting in continuous casting, characterized by starting drawing. 3. A dummy bar in which a dummy bar head provided at an end is connected to a molten metal solidifying shell in a continuous casting mold at the start of casting, wherein the dummy bar head is provided on a rod and one end of this rod. A dummy bar, characterized in that it comprises a locking part which is provided and can be integrated with a molten metal solidified shell in a continuous casting mold, and a connecting part which is provided at the other end of the rod and is detachably attached to the dummy bar body.