JPH0763815B2 - Continuous production method for slabs of unequal thickness - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a running metal belt, a side pool and a rear wall provided on the metal belt, and a molten metal pool formed on the surface of the metal belt. The molten metal is poured, and the molten metal is solidified by removing heat through the metal belt to produce a thin metal strip.In the single-belt continuous casting method, the depth of the molten metal pool is determined with respect to the width direction of the belt. The present invention relates to a method for obtaining a slab having an uneven thickness in the width direction by inclining.

[Conventional technology]

Recently, from molten metal such as molten steel, several mm to several tens, which is close to the final shape
Attention has been paid to a continuous casting method for directly producing a ribbon having a thickness of about mm. According to this method, the hot rolling step is not necessary or can be greatly simplified, and the steps and equipment can be simplified.

A belt method is one of the continuous casting methods. In this method, for example, a molten metal pool formed on an endless running belt is cooled and solidified by removing heat from the molten metal poured through the belt, and the generated shell is accompanied by the running of the belt. The metal ribbon is manufactured by sending it out from the pool. In this belt method, the molten metal is cooled from one direction and the surface opposite to the belt is open. Therefore, there are less restrictions on the arrangement of the nozzles that supply the molten metal from the container such as a tundish to the molten metal pool on the belt.

The present inventors have developed a casting device in which a weir that partitions the side surface of the molten metal pool can be moved in this belt system, and filed as Japanese Patent Application No. 60-155247.

FIG. 4 shows the device proposed in this earlier application. In this device, a metal belt 1 is stretched over a pair of pulleys 2a and 2b so as to travel on an endless track. By holding one pulley 2a high, the endless track of the belt 1 rises toward the pulley 2a. A plurality of heat resistant blocks 3 connected by a chain or the like are arranged around the belt 1, and the 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 pool 4 at the upper portion where the belt 1 travels in a straight line. On the other hand, a fixed weir 6 is provided behind the hot water pool 4. As a result, the basin 4 is formed in which only the traveling direction of the belt 1 is open. Molten metal 8 is poured into the pool 4 from a pouring device 7.

The molten metal 8 poured is removed from heat by a cooling device 9 arranged on the back surface of the belt 1, cooled and solidified into a solidified shell 10. The solidified shell 10 is conveyed rightward in FIG. 4 as the belt 1 moves. Since the heat removal is continued in the course of this transportation, the solidified shell 10 grows into a thin strip 11 having a predetermined thickness and is sent out from the molten metal pool 4.

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

[Problems to be solved by the invention]

By the way, recently, for the purpose of reducing the weight of automobiles and the like, it has been demanded to supply a steel sheet having a unequal thickness in the cross-sectional shape in the width direction as shown in FIG.

However, a slab of unequal thickness in which the wall thickness between the upper surface 11a and the lower surface 11b changes with a uniform inclination angle in one direction will be manufactured by rolling the slab obtained by conventional continuous casting. Then, the slab is likely to bend in the rolling direction or meander during rolling. Therefore, it is difficult to manufacture a non-uniformly thick steel plate from a continuous cast slab.

Therefore, the present invention adds an improvement to the above continuous casting apparatus,
The present invention is applied to the production of unequal-thickness cast slabs, which was practically difficult to produce by this belt casting method, and aims to produce unequal-thickness cast slabs with high productivity.

[Means for solving problems]

In order to achieve the object, the method for continuously producing unequal scale cast slabs of the present invention, in order to achieve the object, a running metal belt, a side weir and a rear weir provided on the metal belt, a pool of metal formed on the belt surface Part, molten metal is poured, and the molten metal is solidified by heat removal through a metal belt to produce a thin metal strip. In the single-belt continuous casting method, the depth of the molten metal pool is set to the belt. It is characterized in that an unequal thickness solidified shell is generated and grown by inclining with respect to the width direction of.

〔Example〕

Hereinafter, the features of the present invention will be specifically described by way of examples with reference to the drawings.

FIG. 1 shows the entire continuous casting apparatus used in the embodiment of the present invention. In FIG. 1, components corresponding to those shown in FIG. 4 are designated by the same reference numerals, and the description thereof is omitted. In addition, the side weir 5, shown in FIG.
Although the cooling device 9 and the like are omitted in FIG. 1, this is for simplifying the drawing, and the cooling device 9 and the like are also provided in the device of FIG.

The molten metal 8 poured from the pouring device 7 into the molten metal pool 4 is
The belt 1 is cooled and solidified to form a solidified shell 10. The thin strip 11 which has passed through the basin 4 and completely solidified is then rolled by the pressure rolls 16a, 16b and the pressure roll 12,
It is wound up as a thin plate coil 14. Depending on the cross-sectional shape of the thin strip 11, an insert may be interposed between the layers of the thin strip 11 at the time of winding to prevent bending and meandering.

In such a continuous casting apparatus, the depth of the pool 4 along the width direction is changed. FIG. 2 shows p- of FIG.
FIG. 3 is a view showing a p section (cross section in the belt width direction), and FIG. 3 is a plan view in the vicinity of the molten metal pool in the method of the present invention. In the same figure, the pp position in FIG. 1 is also shown.

In FIG. 2A, the belt 1 is inclined in the width direction so that the basin 4 becomes shallower from the right side to the left side. Since the surface of the basin 4 is horizontal, if the belt surface is inclined in the width direction, the basin length on the deep side becomes long as is apparent from FIG. Therefore, on the deep side of the basin, the elapsed time from the start to the end of solidification becomes long, and as a result, the plate thickness becomes thicker on the deep side of the basin.

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

In the case of the belt width direction inclination angle θ (radian, β << 1),
The relationship among the molten steel depth d, the cast piece width b, and the pool length l at the position of the fixed weir 6 is as follows. However, the slab thickness is ignored. The subscripts in each formula are 1: the deep side of the basin, and 2: the shallow side of the basin.

d ₁ = d ₂ + b · θ (1) l ₁ = d ₁ · β = (d ₂ + b · θ) β (2) l ₁ = d ₂ · β (3) The solidification pressure S of the slab is generally expressed by the following formula. It is represented by.

S = at ⁿ (4) However, t: transit time of the pool length (= 1 / v) v: casting speed a: proportional constant n: 0.5 to 1.0 Note that n is close to 1.0 when the slab is thin, When thick
Close to 0.5.

From the equations (1), (2), (3), and (4), the thickness ratio of the cast pieces on the thick side and the thin side is expressed by the following equation.

When n = 1.0, the plate thickness distribution becomes linear, but generally n <1.0, so the plate thickness distribution is slightly curved. To avoid this bending, it is effective to coat the belt surface with a coating agent such as BN or SiC to stretch the heat transfer amount in the width direction.

Next, specific operating conditions and properties of the obtained product are shown.

Molten metal 8 having an ordinary steel composition and a temperature of 1580 ° C. was poured into the basin 4 at a flow rate of 300 kg / min. At this time, the hot water pool 4
The belt 1 for supporting the belt 1 was maintained in an inclined state of descending 8 degrees to the right as shown in FIG. 2 (a). In this state, the ribbon
11 was sent out from the basin 4 at a carry-out speed of 12 m / min. The obtained ribbon 11 has a thickness of 6 mm at the left end and 11 mm at the right end.
Therefore, as shown in FIG. 7B, the cross-sectional shape was such that the wall thickness varied in the width direction.

〔The invention's effect〕

As described above, in the present invention, the slab of unequal thickness is manufactured by changing the depth of the molten metal pool in the width direction. This depth change can be easily changed depending on the peripheral surface shape of the leveler, pulley, or the like. Moreover, since the thickness is unequal in the cast state, the manufacturing process becomes extremely easy as compared with the case of manufacturing a unequal-thickness steel plate by rolling a conventional continuous cast slab.

[Brief description of drawings]

FIG. 1 shows the entire continuous casting apparatus used in the embodiment of the present invention, and FIG. 2 shows an example relating to the cross-sectional shape of the molten metal pool in the apparatus. FIG. 3 shows an example of a plan view of the vicinity of the basin in the apparatus. Further, FIG. 4 shows a continuous casting apparatus previously developed by the present inventors.

Claims (1)

[Claims] 1. A molten metal is poured into a molten metal pool formed on the surface of the metal belt by a running metal belt and side and rear weirs provided on the metal belt, and the molten metal is drained through the metal belt. In a single-belt continuous casting method in which a molten metal is solidified by heat to produce a thin metal strip, a unequal-thickness solidified shell is generated and grown by inclining the depth of the molten metal pool with respect to the width direction of the belt. A continuous manufacturing method of slabs of unequal thickness, characterized by: