JPS6039441B2 - Slab hot rough rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of rolling a steel plate by rough hot rolling.

As a matter of fact, the slabs supplied to the hot rolling mill of the hot strip mill as a material to be rolled have been manufactured by blooming a steel ingot.

In the blooming process, the thickness of the slab was determined by considering the finished plate of the steel strip. The portions were small. However,
In recent years, the continuous casting method, which has various advantages over the blooming method, has been industrialized and widely used, so it has become difficult to feed many different types of slabs into the hot rolling mill. .

The reason for this is that in the continuous casting method, the plate m of the slab cannot be changed without replacing the mold, and replacing the mold can greatly reduce the improvement in slab productivity achieved by the continuous casting method. Because it will be. As a result, the amount of change in the thickness of the slab by the hot rolling mill increased significantly. Conventionally, in hot rough rolling, {1} Intermediate rolling method is a method for producing various types of slabs from the same slab.
There are methods such as cross rolling method.

The above method (m) is a method of performing intermediate cutting of slabs using a pair of vertical rolls, and there are two methods: [A] A method using a vertical roll having a flat surface and a method using a vertical roll having a caliber. be.

On the other hand, in the method {2' above, the slab is rotated 900 degrees in the horizontal direction and the inside of the slab is rolled out using horizontal rolls.

However, as shown in FIG. 1, in the intermediate rolling method using vertical rolls 2 having a flat surface of (1'), since the vertical rolls 2 have flat surfaces, the slab 1 by intermediate rolling is deformation is concentrated only at the slab edges.

As a result, the shape of the end of the slab becomes a so-called dogbone shape. Therefore, in the next horizontal rolling, the metal flow in the middle direction of the slab becomes advantageous, and the actual amount of intermediate removal becomes very small by 4. Therefore, at present, the maximum amount of mid-killing is only about a few hundred yards. In order to increase the amount of intermediate removal, it is necessary to increase the amount of reduction of the vertical rolls 2 per pass or increase the number of passes, but in this case, problems such as buckling of the slab or temperature drop occur. In addition, the above [1
}, the intermediate rolling method using vertical rolls having a caliber of {o} increases the deformation area in the middle direction of the slab by the vertical rolls 3 having a caliber, as shown in FIG. The expansion of the slab 1 during flat rolling is smaller than when using vertical rolls with flat surfaces.

Therefore, although a large amount of intermediate removal can be obtained, an increase in the amount of intermediate removal of the slab 1 promotes intermediate defects and fishtail-like shape defects occurring at the front and rear ends of the slab, resulting in a decrease in rolling progress. Therefore, at present, the amount of intermediate kill using this method is about 100. On the other hand, in the cross-rolling method (2) above, it is possible to roll the material completely into the rolling mill, but it is difficult to do so in terms of equipment and efficiency in the current hot strip line.

This invention was made to solve the above-mentioned problems, and when hot rough rolling a slab,
At least one pair of horizontal rolls is provided on the upstream side of a hot assembly rolling mill consisting of a plurality of roll stands, and a pair of dual-purpose rolls having one box caliber and at least one annular projection are provided. The present invention is characterized in that the pair of dual-purpose rolls enables the slab to be removed and removed.

The method of this invention will be explained with reference to the drawings.

FIG. 3 is a schematic explanatory diagram showing one embodiment of the method of the present invention.

In FIG. 3, 4 is a heating furnace, 5 is a slab heated to a predetermined temperature in the heating furnace 4, 6 is a known hot rolling mill consisting of a plurality of roll stands, and 7 is a hot roughening mill. A crop shear 8 installed on the exit side of the final roll stand of the rolling mill 6 is a known hot finishing rolling mill consisting of a plurality of roll stands installed on the exit side of the crop shear 7; is a coiler installed on the exit side of the final roll stand of the hot finishing mill 8.

In FIG. 3, 1 is a pair of horizontal rolls installed upstream of the first roll stand of the hot rolling mill 6, and 11 is a pair of dual-purpose rolls installed upstream of the horizontal roll 10. Both are capable of reverse rolling. The dual-purpose roll 11 each has one box caliber 12 and one annular projection 13, as shown in FIG. 4a.

As shown in FIG. 4b, two annular projections 13 may be provided. In either case, in order to effectively eject the inside of the slab 5, the annular projection 13 needs to satisfy the following relational expression. 2W, Mi (slab medium/2), 2W222W. , day, Z (reduction amount/2) However, ZW,: sum of W, in the top of the annular protrusion 13, ZW2:
Sum of middle W2 at the bottom of the annular projection 13, day,: annular projection 1
3 height.

Further, in order to effectively perform the intermediate cutting of the slab 5, the box caliber 12 needs to satisfy the following relational expression.

W3S slab thickness, W4≧W3, Day 2<(in slab)/2.

However, W3: Inside the bottom of the box caliber 12 W4: Inside the top of the box caliber 12 Day 2: Depth of the box caliber 12.

In addition, in FIGS. 4a and 4b, D. indicates the roll outer diameter of the annular projection 13 portion, and D2 indicates the roll outer diameter of the horizontal portion.

In this way, by using a pair of horizontal rolls in combination with a pair of dual-purpose rolls having one box caliber and at least one annular protrusion, it is possible to perform both mid-cutting and mid-filling of slabs. The most important feature of this invention is that it can be carried out.

The combination of the horizontal roll 10 and the dual-purpose roll 11 is the third
Although not shown in the drawings, the horizontal roll 0 may be installed first, the dual-purpose roll 11 may be installed downstream of the horizontal roll 0, and the horizontal roll 10 may be further installed downstream of the horizontal roll 0. It is desirable that the pair of horizontal rolls 10 and the dual-purpose roll 11 be installed upstream of the first roll stand of the hot rolling mill 6 and downstream of the heating furnace 4, respectively. It may be installed after the cutting process of the slab by continuous casting, and medium change rolling may be performed using the sensible heat of the slab.

In the hot rough rolling mill 6, as in the past, the slab is rolled so as to eliminate medium defects at the tip of the slab and medium fluctuations at the center of the slab, in order to improve the accuracy of medium dimensions in the finished plate of the steel strip. . Next, an example of the method of this invention will be described.

By the method of this invention, a slab was emptied.

The rolling conditions at this time are the horizontal roll 10 and the dual-purpose roll 1.
1 and were arranged as shown in FIG. 3, and the rest were as shown in Table 1. Table 1 The results are shown in FIG.

From FIG. 5, it is clear that when a slab is rolled by the method of the present invention, the amount of creaminess is proportional to the amount of rolling reduction. Next, the slab was rolled out under the same rolling conditions as in Table 1 except that the rolling reduction of the horizontal roll 10 was 5 mm.

The results are shown in FIG. From FIG. 6, it can be seen that a considerable spread can be obtained even by horizontal rolling using the horizontal roll 0' for flattening the rolled portion of the slab 5 by the annular protrusion 13.
It is also clear that the amount of creampie can be easily controlled since the total spread in the middle is in a linear relationship with the amount of rolling down of the dual-purpose roll 11. Next, by the method of the present invention, the slab was cut in the middle.

The rolling conditions at this time are shown in Table 2. In this rolling process, the slab 5 was rolled in the middle direction by the box caliber 12 for 1 to 4 passes, and then rolled by the horizontal roll 0' for 1 pass. Table 2 As a result, it is clear that the amount of intermediate reduction of the slab 5 has a linear relationship with the total reduction amount in the middle direction of the slab 5 by the box caliber (reduction amount in the middle direction of the slab per pass x number of passes). It can be seen that the amount of intermediate cutting of the slab 5 can be easily controlled.

Next, Table 3 shows examples of slab rolling by the method of the present invention. Table 3 In Table 3, rolling mill row A shows the combination of horizontal roll 10 and dual-purpose roll 11, and B shows the combination of hot rough rolling mill 6.
shows.

As is clear from Table 3, by using the dual-purpose roll 11, the amount of change in the slab can be increased to a large extent, and as a result, the medium pitch of the continuous casting slab can also be increased to a large pitch as shown in Table 3. I can do it.

As explained above, according to the present invention, by installing a combination of horizontal rolls and dual-purpose rolls on the upstream side of a hot rolling mill, it is possible to increase the amount of medium change in slabs. This brings about the extremely useful effect that slabs can be rolled without reducing the productivity of slabs produced by the continuous casting method.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing how a slab is rolled by vertical rolls, FIG. 2 is a front view showing how a slab is rolled by vertical rolls with calibers, and FIG. 3 is a front view showing how a slab is rolled by vertical rolls with calibers. FIG. 4a is a front view of a dual-purpose roll used in the method of the present invention,
Same b is also used for other purposes.

5 and 6 are diagrams showing the relationship between the amount of reduction and the amount of creampie achieved by the method of the present invention, and FIG. FIG. In the drawing, 1...slab, 2...
... Vertical roll, 3 ... Vertical roll with caliber, 4 ... Heating furnace, 5 ... Slab, 6 ... Hot assembly rolling mill, 7. ... Crop shear, 8 ... Hot finishing rolling mill, 9 ...
・Coiler, 10...Horizontal roll, 11...Dual use roll, 12...Box caliber, 13...
...annular process.

Figure 1 Figure 2 Figure 3 Figure 7 Figure 4 (4) Figure 4(b) Figure 5 Figure 6

Claims (1)

[Claims] 1. When hot rough rolling a slab, at least one pair of horizontal rolls is provided on the upstream side of a hot rough rolling mill consisting of a plurality of roll stands, and one box caliber and at least one annular roll are provided. 1. A method for hot rough rolling of a slab, characterized in that a pair of dual-purpose rolls having projections are provided, and the pair of dual-purpose rolls can widen and narrow the slab.