JPS587362B2 - Thick plate rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for rolling a thick plate by which a plurality of plates can be obtained from a formed rolled material.

Plate rolling is made-to-order, and the dimensions of ordered products vary widely, so products with similar properties such as wall thickness, width, length, and specifications are joined in the width direction or length direction. A single rolled material is formed, and after rolling, it is cut into required dimensions on a shearing line to produce products.

However, if it is not possible to combine only products with the same properties, the rolled material 10 is designed by combining products 10A and 10B with different width dimensions as shown in FIG. 1A, and Product 12A with different lengths,
The rolled material 12 is designed by combining 12B.

Such a combination design allows rolling in a shape that approximates the maximum dimension of rolling capacity, and is advantageous in terms of rolling efficiency, yield, and slab design.

In addition, the rolling dimensions are also determined by the minimum slab size that can be charged into the heating furnace, and products may be collected to meet this rolling dimension.

However, when products of different widths and lengths are combined, losses occur as shown by diagonal lines in FIGS. 1A and 1B, respectively.

The present invention takes the above-mentioned facts into account, and provides a thick plate rolling method in which a plurality of thick plates are produced from a single rolled material, and the loss is extremely small by designing a combination of a plurality of plates. is the purpose.

The thick plate rolling method according to the present invention is a method of forming a rolled material with an irregular planar shape from a thick plate rolled material, and calculates a change in the thickness of the material based on a dimensional change in the planar shape of the rolled material using the constant volume law. Then, by changing the amount of reduction during rolling to form a rolled material with different wall thicknesses in the rolling direction, and then turning this rolled material 90 degrees and rolling, the width direction or It has become possible to efficiently produce thick plates with various planar shapes by forming rolled materials having planar shapes with different length distributions in the longitudinal direction.

Embodiments of the present invention will be described below with reference to the drawings.

The first embodiment of the present invention is an embodiment in which thick plates having different product widths are obtained.

In the rolling of thick plates, it is normal to perform one or more forming passes in the longitudinal direction of a heated slab in a rolling mill, but during the rolling of these forming passes, the amount of reduction is changed and the second A. As shown in the figure, a rolled material 14 whose wall thickness is changed from the middle part in the rolling direction is formed.

Note that the arrow L indicates the rolling direction of the forming pass, and generally it is easier to control the wall thickness to increase it than to decrease it from the middle of rolling.

Thereafter, this rolled material is turned 90 degrees and a width pass (in the direction of arrow W in FIG. 2B) is performed to form a rolled material 16 until the width is calculated in advance and reaches a predetermined thickness.

After this width pass, the rolled material is further turned 90 degrees and a forming pass is performed to form a different width rolled material 18 as shown in FIGS. 2C and 3. By cutting the product 20 (length l2/
2, width is h1) and product 22 (length is l1/3, width is h
0) can be obtained.

Next, when calculating the dimensions of the rolled material 14 shown in FIG. 2A that are necessary to obtain the cross-rolled material 18 shown in FIG. 3, the amount of plate thickness variation during the forming pass shown in FIG. Δt (=t0-t1) is, where Δh=h0-h
There is one.

As a result, the rolled material 14 shown in Fig. 2A is formed by rolling with the wall thickness calculated using this formula (3) and immediately lowering the rolling pressure after reaching the length Lt, and the rolling material 14 shown in Fig. 2A is formed, and the rotation of the rolls is applied to reach Lt. It is possible to measure with a length meter etc.

Next, this Lt is determined by calculation. If the rolling length at plate thickness t0 is set to L0 as shown in FIG. 2A, the following equation holds true from the law of constant volume.

Using this equation (8), the length to be rolled with the wall thickness t1 can be determined.

Here, ΔL is a length close to the roll contact length, so it can be calculated in advance from the roll diameter and Δt.

Next, by inserting specific values into equations (3) and (8) above, the slab dimensions are 215 x 1615 x 2844 mm (
7,752 kg), and the rolling dimensions are 10 x 3,000 (h0 in Figure 3) or 2,800 (h1 in Figure 3) x 30,000.
(Fig. 3 l0), and the dimensions shown in Fig. 3 are 10×
There are two products 20 with dimensions of 2800 (h1) x 6000 (l2/2 in Fig. 3) and dimensions of 10 x 3000 (h in Fig. 3).

) × 6000 × (Fig. 3 l1/3) When calculating the case where three products 22 are manufactured, the shape after rolling is as shown in Fig. 4, and line A in Fig. 4 is the actual measurement point. It is shown.

When this product 20.22 was actually produced, the improvement in yield effect was 2.33%.

Next, the case where the present invention forms rolled materials of different lengths will be explained using a second embodiment.

In this embodiment, the rolled material 24 is formed from a slab of raw material by forming passes as shown in FIG. 5A.
During this forming pass, the thickness of the rolled material is made uniform.

Thereafter, this rolled material is turned 90 degrees and a plurality of widening passes are performed, and in the final pass of this widening pass, a rolled material 26 whose wall thickness is changed in the widening direction as shown in FIG. 5B is formed.

This rolled material 26 is then turned 90 degrees again, and a cross bend adjustment, length adjustment pass, and normal final rolling form the rolled material 28 shown in FIGS. Products 30 to 36 of different sizes are available.

Here, the final width determining pass shown in FIG. 5B is a pass for determining the width, and since it is necessary to improve the width accuracy, the wall thicknesses t0 and t1 of the rolled material 26 are determined by calculation.

In order to obtain the dimensions of the rolled material 26 shown in FIG. 5B from the material with the slab width H, from the relationship of constant volume, Δt=to-t1 (1
1) Furthermore, if the shape of the rolled material 28 is set to dimensions as shown in FIG. 6, the following equation holds true according to the law of constant volume.

from now If you transform this This determines the thickness of the rolled material 26.

In addition, when normal rolling is performed in the initial stage where the plate is turned 90 degrees and rolled in the longitudinal direction after the plate thickness has been varied, lateral bending is likely to occur. When forming, it is necessary to equalize the amount of protrusion at the front and rear ends in the longitudinal direction to facilitate rolling.

These problems can be solved by rolling with a rolling reduction of 2% or less, and rolling as normal until the thicker remaining part becomes as thick as the thinner part. Confirmed by experiment.

Furthermore, since the rolling width of the front and rear end protrusions of the rolled material 28 shown in FIG. This can be solved by making the rolling load per meter of width less than twice the rolling mill rigidity.

Next, the dimensions of the rolled material 28 shown in FIG. 6 above are h0=2
000mm, h=2800mm, l2=840Cmm,
l3=3600mm, l4=9000mm, l5=10
000mm, the wall thickness is 20mm, and the raw material slab dimensions are 260 x 1890 x 4000 mm (15430 kg)
The experimental results for the case are shown in FIG.

This FIG. 7 shows the longitudinal dimension and rolling width measured from the reference line shown in FIG. 6 toward the end.

FIG. 8 shows changes in the thickness of a material with a width of 2800 mm, and in both cases, the object of the present invention is certainly achieved.

The improvement in the yield effect in this second embodiment is 2.
It is 54%.

Next, a third embodiment will be described in which the present invention is applied to the production of extremely thick head plates required for nuclear reactors, pressure vessels, etc.

As shown in FIG. 9A, in the final pass of the forming pass, the reduction amount is changed during rolling to form a rolled material 40 having two maximum wall thicknesses in the longitudinal direction.

After that, this rolled material is turned 90 degrees and a widening pass is performed, but even during this proposed pass, if the rolling amount is changed during rolling so that the middle part in the rolling direction has the maximum thickness, the rolling The shaded portion of the material 42 shown in FIG. 9B bulges outward due to the thickness change in the previous molding pass.

Thereafter, by further turning this rolled material 90 degrees and performing a forming pass as shown in FIG. 9C, it is possible to obtain mirror plates 46 and 48 from the rolled material 44 with extremely small cut-off portions.

The rolling method in this third embodiment is such that when the rolled material 50 having the shape shown in FIG. 10 is rolled by turning it 90 degrees, the thick part shown in FIG. 10 is shown in FIG. 11. This can be considered quite easily if we consider that it appears as a change in the width dimension of the rolled material 52.

In addition, in order to obtain a circular product such as a mirror plate, various control methods can be considered, such as controlling the number of roll rotations during biting, or keeping the number of roll rotations constant and controlling the rolling speed.

Next, as concrete numbers, the slab dimensions are 280 x 2000.
Considering the case of designing a mirror plate with a thickness of 95 mm and a diameter of 3800 mm, the dimensions of each part shown in Fig. 10 in the final molding pass are t1 = 20 mm.
0mm, HG=2000mm, L0=3182mm, t
O=240 mm, and after rolling this rolled material 50 by turning it 90 degrees, the rolled material 52 shown in FIG. 11 has l6=3.
333mm, l7=3182mm, l8=4000mm
becomes.

If this rolled material 52 is further rotated 90 degrees and rolled to a thickness of 95 mm, l7 will also be 4000 mm, making it possible to obtain the desired planar shape, and the yield in this case is 92.1%.
It is.

Yield is 12.11% compared to 80% in normal rolling.
It was expected that the yield rate would improve.

As explained above, the thick plate rolling method according to the present invention forms a rolled material whose wall thickness changes by changing the amount of reduction during rolling, and then rolls the material by turning it 90 degrees to form a planar shape with different dimensions from the middle part. Since a rolled material having a . be.

The present invention is particularly effective because it can be achieved without changing conventional rolling processes and equipment.

[Brief explanation of the drawing]

Figures 1A and 1B are plan views showing the conventional rolling method;
2A to 2C are perspective views showing the first embodiment of the thick plate rolling method according to the present invention, FIG. 3 is a plan view showing the rolled material after forming, and FIG. 4 is an actual measurement of the rolled material after forming. Diagram showing dimensions,
5A to 5C are perspective views showing the rolling order of the second embodiment of the present invention, FIG. 6 is a plan view showing the rolled material after forming,
Figures 7 and 8 are plan views showing measured dimensions of the rolled material after forming, Figures 9A to 9C are perspective views showing the thick rolling order of the third embodiment of the present invention, and Figure 10 is the third embodiment. FIG. 11 is a perspective view showing the rolled material used for rolling, and FIG. 11 is a plan view showing the rolled material during rolling. 14,16,18...Rolled material, 24,26.28...Rolled material, 40,42,44...Rolled material, 50,52...
Rolled material.

Claims (1)

[Claims] 1 A method of forming a rolled material having an irregular planar shape with different length distribution in the width direction or longitudinal direction from a thick rolled material, the wall thickness of the material being determined based on the constant volume law based on the dimensional change in the planar shape of the rolled material. Calculate the change, change the amount of reduction during rolling to form a rolled material number whose wall thickness changes in the rolling direction, and turn this rolled material 90 degrees and roll it to change the width direction of the dimension from the area where the amount of reduction was changed. Or a thick plate rolling method characterized by forming a rolled material having a planar shape with a different length distribution in the longitudinal direction.