JPS63290658A - Continuous producing method for cast strip having unequal thickness - Google Patents

Abstract

PURPOSE:To improve productivity of a cast slab having unequal thickness by inclining depth of pouring basin part toward width direction of a belt and transferring heat of molten metal in the pouring basin part through the belt. CONSTITUTION:The pouring basin part 4 in continuous casting apparatus is inclined toward width direction of the belt 1 and the belt surface 1 is inclinationally arranged. The molten metal 8 poured into the pouring basin part 4 from a pouring device 7 is cooled and solidified on the belt 1 and a solidified strip 11 is rolled with pressurized rolls 16a, 16b and 12 respectively, to wind as strip coil 14. When the molten metal 8 solidifies, solidification time at the deep side in the pouring basin part becomes longer and the strip thickness at this side becomes thicker. Change of the depth is easily executed by change of peripheral face shape of leveller, pulley, etc., and the production process of the cast strip having unequal thickness is simplified. By this method, the productivity of the cast strip having unequal thickness is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is aimed at producing slabs continuously by cooling and solidifying molten metal on a running belt, by improving the shape of the belt. This invention relates to a method for obtaining slabs having unequal thickness in the width direction.

[Conventional technology]

BACKGROUND ART Recently, a continuous casting method has been attracting attention, in which a thin ribbon having a thickness of several mm to several tens of ma+, which is close to the final shape, is directly manufactured from molten metal such as molten steel. When using this method, the hot rolling process is not required or can be significantly simplified, and the process and equipment can be simplified.

One of these continuous casting methods is a belt method. In this method, for example, a pool is formed on a belt that runs endlessly, and the molten metal poured into the pool is cooled and solidified by heat removal through the belt, and the resulting shell is released as the belt runs. The molten metal is then sent out from the pool to produce metal ribbon. When using this belt method, the molten metal is cooled from one direction, and the surface opposite to the belt is open. Therefore, there are fewer restrictions on the arrangement of nozzles that supply molten metal from a container such as a tandinyu to a sump on the belt.

The inventors of the present invention have developed a casting device using this belt method in which the weir that partitions the side surface of the basin can be moved, and has filed an application for this as Japanese Patent Application No. 155247/1983.

FIG. 4 shows the device proposed in this earlier application.

In this device, a metal belt 1 is connected to a pair of boots +
J2a and 2b have been given a hook and are designed to run on endless tracks. By holding one pulley 2a high, the endless track of the belt 1 is
It will rise towards 2a.

A plurality of heat-resistant blocks 3 connected by chains or the like are arranged around the bell l-1, and these heat-resistant blocks 3 move in synchronization with the running of the belt 1.

The heat-resistant block 3 serves as a side weir 5 that partitions the side of the sump 4 at the upper portion where the belt 1 runs linearly. On the other hand, at the rear of the water reservoir 4, a fixed t[I6 is provided.

As a result, a trough portion 4 is formed that is open only in the direction in which the belt 1 moves.

Molten metal 8 is poured into this pool 4 from a pouring device 7.

The poured molten metal 8 is heated by a cooling device 9 disposed on the back side of the belt 1, cooled and solidified, and becomes a solidified shell 10. This solidified shell 10 is conveyed rightward in FIG. 4 as the belt 1 moves. Since heat continues to be removed during this transportation process, the solidified shell 10
grows into a thin ribbon 11 with a predetermined thickness, and is sent out from the pool 4.

This thin strip 11 is then rolled to a target thickness by a pressure roll 12, and a thin coil 14 is rolled by a winding device 13.
It is wound up as.

[Problem that the invention seeks to solve]

Incidentally, recently, for the purpose of reducing the weight of automobiles and the like, there has been a demand for the supply of steel plates having unequal thicknesses in cross-sectional shape in the width direction, as shown in Fig. 2, etc.

However, the upper surface 11a has a uniform inclination angle in one direction.
The unequal thickness slab in which the wall thickness between and the lower surface 11b changes,
When a slab obtained by conventional continuous casting is manufactured by rolling, the slab tends to bend or meander in the rolling direction during rolling. For this reason, it is difficult to manufacture steel plates of unequal thickness from continuously cast slabs.

Therefore, the present invention improves the above-mentioned continuous casting apparatus,
The purpose of this method is to apply this belt casting method to the manufacture of slabs of unequal thickness, which has been practically difficult to manufacture in the past, and to manufacture slabs of unequal thickness with high productivity.

[Means for solving problems]

In order to achieve the purpose of the continuous production method of slabs of unequal thickness according to the present invention, the molten metal is cooled and solidified by cooling and solidifying the molten metal poured into a pool provided on a belt running upwardly. When manufacturing a ribbon, the depth of the pool is inclined with respect to the width direction of the belt, and the molten metal in the pool is heat removed through the belt to generate and grow a solidified shell. [Examples] Hereinafter, the features of the present invention will be specifically explained by Examples with reference to the drawings.

FIG. 1 shows the entire continuous casting apparatus used in the embodiments of the present invention. In FIG. 1, parts corresponding to those shown in FIG. 4 are indicated by the same reference numerals, and their explanations are omitted. In addition, the side weir 5 shown in Figure 4
．． Although the cooling device 9 and the like are not shown in FIG. 1, this is to simplify the drawing, and the device shown in FIG. 1 is similarly provided.

The molten metal 8 poured from the pouring device 7 into the pool 4 is
It is cooled and solidified on the belt 1 to become a solidified shell 10.

The ribbon 11 that has completely solidified after passing through the pool 4 is then rolled by the pressure rolls 16a, 16b and the pressure roll 12, and then wound up as a thin plate coil 14. Depending on the cross-sectional shape of the ribbon 11, an insert may be interposed between the layers of the ribbon 11 during winding to prevent bending or meandering.

In such a continuous casting apparatus, the depth of the tundish portion 4 along the width direction is changed. Figure 2 shows p- in Figure 1.
FIG. 3 is a diagram showing a p-section, and FIG. 3 is a plan view of the vicinity of the hot water pool in the method of the present invention. In the figure, the pp position in FIG. 1 is also shown.

In FIG. 2(a), the belt 1 is inclined in the width direction so that the pool 4 becomes shallower from the right side to the left side. Since the surface of the sump portion 4 is horizontal, if the belt surface is inclined in the width direction, the length of the sump on the deeper side becomes longer, as is clear from FIG. 3. For this reason, the elapsed time from the start to the completion of solidification becomes longer on the deeper side of the pool, and as a result, the plate thickness becomes thicker on the deeper side of the pool.

The distribution of slab thickness in the width direction is determined as follows.

In the case of the belt width direction inclination angle θ (radian, β<<1), the relationship between the molten steel depth d, the slab width b, and the sump length l at the fixed weir 6 position is as follows. However, the slab thickness is ignored. The subscript in each formula is 1 - the deep side of the intestinal sump;
2: It is on the shallow side of the pool.

d, = d2+b・θ (1) 1 +
= d +・β= (d2+b・θ)β (2) β1
=d2·β (3) The solidification pressure S of a slab is generally expressed by the following formula.

3=at'' (4) where, t: Passage time of sump length (=1/V) V: Casting speed a: Constant of proportionality n: 0.5 to 1.0 In addition, n is when the slab is thin. Close to 1.0, and close to 0.5 when thick.

From equations (1), (2), (3), and (4), the slab thickness ratio between the thicker side and the thinner side is expressed by the following equation.

When n=1.0, the plate thickness distribution is linear, but generally n<l, Q, so the plate thickness distribution is somewhat curved. If you want to avoid this curvature, make the belt surface BN,
An effective method is to coat with a coating agent such as SiC to adjust the amount of heat transfer in the width direction.

Next, specific operating conditions and properties of the obtained products will be shown.

Molten metal 8 having a common steel composition and a temperature of 1580°C was heated to 30
The water was injected into the sump 4 at a flow rate of 0 kg/min. At this time, the belt 1 supporting the water pool 4 was maintained in an inclined state descending 8 degrees to the right as shown in FIG. 2(a). In this state, the thin strip 11 is transferred to the hot water pool 4 at a speed of 12 m/min.
Sent from. The obtained thin ribbon 11 has a thickness of 6 at the left end.
The thickness of the right end was 11 m+n, and the cross-sectional shape had a wall thickness that varied in the width direction, as shown in the same figure.

〔Effect of the invention〕

As explained above, in the present invention, slabs of variable thickness are manufactured by changing the depth of the sump in the width direction. This depth can be easily changed depending on the shape of the peripheral surface of the leveler, boob, etc. Moreover, since the thickness is unequal in the cast state, the manufacturing process is extremely easy compared to the conventional method of manufacturing a steel plate of unequal thickness by rolling a continuously cast slab.

[Brief explanation of drawings]

FIG. 1 shows the entire continuous casting apparatus used in the embodiment of the present invention, and FIG. 2 shows an example of the cross-sectional shape of the sump in the apparatus. FIG. 3 shows an example of a plan view of the vicinity of the hot water reservoir in the device. Moreover, FIG. 4 shows a continuous casting apparatus that was previously developed by the present inventors.

Claims (1)

[Claims] 1. When manufacturing a metal ribbon by cooling and solidifying molten metal poured into a pool provided on a belt that runs upwardly, the depth of the pool is determined by the depth of the belt. 1. A method for continuously manufacturing slabs of unequal thickness, characterized in that a solidified shell is generated and grown by tilting the slab in the width direction and removing heat from the molten metal in the pool through the belt.