JPS63174761A - Twin belt type continuous casting machine - Google Patents

Abstract

PURPOSE:To stabilize the operation by forming a protruded bending curve at the side face of an upper portion of a side plate for a mold and also forming a recessed bending curve toward a belt direction at the side face of a lower portion. CONSTITUTION:The fixed side plate 11 composing of a mold for coontinuous casting is formed, so that its upper side face containing a molten metal surface position has a protruded bending curve to a cooling pad 12 direction. Further, the side face of the lower portion for the fixed side plate 11 is formed, so as to have the recessed bending curve to the cooling pad 12 direction, that is, the belt direction. In this way, in the upper range of the molten metal pool, the belt 3 is pushed to the fixed sided plate 11 direction by belt tension T, to secure air-tight of the mold. In the lower portion of the mold, as the side face of the side plate 11 is formed to the recessed shape, the tightening to the short side is executed by the belt 3. Therefore, the insertion phenomenon of molten metal in the mold is eliminated and the operation of continuous casting is stably executed without any interruption.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a twin-belt continuous casting machine for producing slabs.

[Conventional technology]

As described in JP-A-58-38640 and JP-A-60-9553, the twin-belt continuous casting machine forms a mold with a pair of belts that move in synchronization with the slab and a fixed side plate. The molten metal is pooled in this mold, and the molten metal is cooled and solidified on the belt surface to perform continuous casting. The conventional double-belt type short-side drawing type continuous casting method will be explained below with reference to FIG.

The molten metal in the tundish 1 is poured through an immersion nozzle 2 into a mold consisting of a pair of stationary side plates 4, 4' and belts 3, 3'. In order to keep the molten metal surface 21 in the mold constant,
The pouring flow rate is controlled in accordance with the withdrawal speed of the U piece 9. Therefore, a molten metal pool 22 with a constant level is formed in the mold, and a solidified shell 23 grows and moves downward in synchronization with the speed of the belt 3. And the slab 9 is completely l inside the mold.
! It is hardened and pulled out to the desired thickness. The diameter of the immersion nozzle 2 in the pouring part is when the thickness of the steel plate to be cast is around 30 mm.
The distance between the immersion nozzle and the belt is at least 100 m, and the distance between the immersion nozzle and the belt is 20 to 30 m to avoid solidification of the molten metal. The upper part is expanded in an arc or tapered shape, and the lower part is narrowed down to the desired thickness (short side).

The belts 3, 3' are in the molten metal pool 22.

Since it is necessary to support and cool the high-temperature molten metal, cooling pads 5 and 5' are arranged on the back, and cooling water is supplied through the water supply hole 10 between the belt 3゜3' and the pad 5.5'. Forms a water film to suppress belt temperature rise, allowing continuous use. The thickness of the water film is usually 0.5 to 1.0 m or more.

[Problem that the invention seeks to solve]

The conventional system configured in this way has already been proven to be faster and of higher quality, but as shown in Figure 8, casting 20 occurs and operation must be stopped, resulting in unstable plant operation. It may impede operations.

The cause of the casting is due to the curved surfaces of the fixed side plate 4 and the cooling pads 5, 5, which are provided to narrow down the molten metal pool and are convex toward the inside of the mold, and the tension T of the belt 3°3'. The reason is that the belts 3, 3' are pressed against the cooling pad 5.5' side with the following pressing surface pressure P kg/rs''.

P: Belt average pressing surface pressure kg/m”
σ: Belt tension kg/m”h
: Belt thickness ■R1: Squeezing curvature radius For example, ty = 10k
g/m”, h = 1011111. R1:150
At 011vI, a pressing surface pressure of P==0.6'Ikg/m'' acts uniformly on the cooling pad, but this occurs before the molten metal is poured into the mold, as shown in Figure 9. This is the case in the no-load state.When molten metal is poured, as shown in Fig. 10, the tension P at the center of the belt corresponding to the pouring width is
c decreases and the tension Pe at the belt end increases, so the pressing surface pressure of the belt end against the cooling pad becomes excessive than the pressure of the cooling water film formed between the belt and the pad, and the belt This means pressing the cooling pad 5.5' to the side. For example, if the water film thickness is 0.5 mm, the belt 3.
3' is pressed against the cooling pads 5, 5', the gap between the fixed side plates 4, 4' and the belts 3, 3' increases to a maximum of 0.5 m, exceeding the molten metal insertion limit of 0.2+m.

The reason why the pressing surface pressure Pc at the center of the belt decreases in the presence of molten metal is that as shown in FIG. This is because the tension is relaxed due to thermal expansion. On the other hand, since the total force of the belt is constant, the tension at the end of the belt is
Therefore, the pressing surface pressure Pe of the belt end increases. If this is the general formula % formula % 1200 + m (B is belt width) and b = 1000111, then PC is 20, Pe = (120XO-67-0) 4
．． 02/mo+”120-1o.

In other words, a mechanism is required to ensure a pulsed water film pressure higher than this, but in the conventional method, water leaks from the belt end, so the pressure actually decreases, and it is difficult to maintain pressure above Pa. It is.

Therefore, as shown in FIG. 8, belts 3, 3' and fixed side plate 4
, 4' can no longer adhere tightly, creating gaps 20
will occur. When casting occurs in this way,
If it becomes difficult to draw out the slab or if the drawing force is strengthened, problems such as belt breakage occur, resulting in unavoidable interruptions in operation and reduced spinning mold life.

An object of the present invention is to provide a twin-belt continuous casting machine that eliminates the occurrence of such casting.

[Means for solving problems]

Next, the present invention will be explained with reference to FIG. The purpose is to form the fixed side plate 11 constituting the mold so that the side surface of the upper portion including the molten metal surface device has a convexly curved curve in the direction of the belt, and the side surface of the lower portion of the fixed side plate has a curved curve convexly in the direction of the belt. This is achieved by creating a shape with a curved line.

[Effect]

The present invention will be explained in detail with reference to FIG. Now belt 3 is
Fixed side plate 11. When the cooling pad 12 is stretched into a curved gap as shown in the figure with a tension T, R
In the curved portion with a radius of curvature of 2, the belt is pressed against the stationary side plate 11 in the direction of the leftward arrow in the figure due to the tension T, and in the portion with the radius of curvature of R1, Conversely, a pressing force is applied toward the cooling pad on the right side of the figure.

Therefore, if the mold is formed to have a radius of curvature R2 in a range where the solidified shell is not yet formed and is likely to be a hot water jug, the belt will be pressed against the stationary side plate in that range and will come into close contact with the fixed side plate.

〔Example〕

An embodiment according to the present invention will be described using FIGS. 2, 3, and 4. Since the basic structure is the same as the conventional one, a detailed explanation will be omitted, but the reference numerals attached to the figures are the same as those in the explanatory diagrams of the conventional example.

In Figures 2 and 3, the fixed side plate 11 and the cooling pad 12'
In the area H1 above the molten metal pool 22, the belt 3' is pressed by the tension of the belt in the direction of the side surface of the stationary side plate 11, and the shape of this side surface 14 is a convex shape in the direction of the belt with a curvature of half 'lk Rz. shape, molten metal pool 22
In the lower area H2, the side surface of the stationary side plate 11 has a concave shape in the belt direction with a radius of curvature R1, as in the conventional case.

Belt 3' performs narrowing work on the short side.

If such a configuration is used, whether there is a solidified shell 23 or not,
Alternatively, in the region of the molten metal pool 22, which is extremely thin, as shown in FIG. 4, the belt 3°3' is pressed in the direction of the stationary side plate 11, 11' by the belt tension T, so that the sealing of the mold is ensured. be done. That is, in contrast to the conventional mechanism in which a mold gap is generated due to external forces such as thermal deformation of the belt, static pressure of the molten metal, and direct impact of the molten metal at the initial stage of pouring, the present invention is as shown in FIG.

Since the car P6 that tightens the side surface 14 of the fixed side plate 11, 11' is always acting, a reliable mold sealing action can be used.

It should be noted that the force of -Pa is always applied to the side surface 14 of the fixed side plate 11, 11'.
Since the belts 3 and 3' are pressed against each other, there is a concern about wear caused by sliding of each belt.

By appropriately selecting the ratio R2 and supplying lubricating oil, wear can be suppressed to a level that can be used for practical purposes.

By setting the center of curvature of the curved surface at the top of the long side of the mold to the molten metal side as shown in Figure 3, the cross-sectional size will be 30 m.
When casting a steel plate of X i OOOm, the surface area of the molten metal was conventionally about 30r *
= 2000 cd, which can be reduced to about 1/1.5, reducing the temperature drop due to heat radiation from the molten metal surface, and reducing the need for soft refractories used for the fixed side plates 11 and 11', reducing running costs. It also has a ripple effect that also contributes to the decline.

In this example, the side surface of the fixed side plate has one curve with a radius of curvature that is convex toward the belt, and one curve with a concave radius of curvature that follows this, but it is possible to combine multiple curve shapes. It may be a curve.

In addition, by providing a partition inside the cooling pad to separate the center and the ends, increasing the water pressure at the end to expand the cooling pad, and bending the belt end toward the fixed side plate, it is effective in preventing the occurrence of overcasting. can be raised.

【Effect of the invention〕

According to the present invention, a double-belt continuous casting machine composed of a belt and a fixed side plate can operate stably, and the range of use of refractories used for the side plates is further reduced.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the operation of the present invention, Fig. 2 is a front view showing an embodiment of the fixed side plate according to the invention, Fig. 3 is a front view showing the mold part of the embodiment according to the invention, Fig. 4 is a cross-sectional plan view of FIG. 3, FIG. 5 is a tension distribution diagram in the width direction of the belt in the part where the radius of curvature of the wall surface of the mold according to the present invention is RX, when no load is applied, and FIG. 6 is a diagram showing the tension distribution when loaded. A diagram showing the distribution, Figure 7 is a front view of the conventional double-belt two-continuous casting W1vI type, and Figure 8 is the
Figure 9 is a cross-sectional view of the belt in the conventional mold in the width direction when no load is applied, Figure 10 is the tension distribution diagram when the belt is loaded, and Figure 11 is the temperature when the belt is loaded in the width direction. It is a distribution map. 3.3'...Belt, 4,4'...Fixed side plate, 5,
5'... Cooling pad, 9... Fin piece, 11.11'.
...Fixed side plate, 12.12'...Cooling pad, 21.
... Molten metal surface, 22...ts hot water pool.

Claims (1)

[Claims] 1. A pair of side plates forming the wall surface on the short side of the slab, and a pair of side plates that sandwich the side surfaces of the side plates and move in synchronization with the slab to form the wall surface on the long side of the slab. a mold consisting of a pair of belts to be formed, and a cooling pad that presses and guides the belt in the side direction of the side plate, and pours molten steel from above,
In a twin-belt continuous casting machine that draws slabs from below, the side surface of the upper portion of the side plate including the molten metal surface device has a curve convexly curved in the direction of the belt, and the side surface of the lower portion of the side plate is curved in the direction of the belt. A twin-belt continuous casting machine characterized by a shape having a concave curve.