JPS63188402A - Width sizing method for hot slab - Google Patents

Abstract

PURPOSE:To reduce crop losses by changing and adjusting a ratio between an edge draft amount of a hot rolled slab by an edging press and an edge draft amount by a vertical rolling mill in the uppermost position in a rough rolling mill group. CONSTITUTION:A hot rolled slab 1 casted by a continuous casting machine, etc. is largely, first, edged by an edging press P and then is alternately subjected to edging and thickness drafting by a vertical rolling mill group of VSB, E2, E3... and a horizontal rolling mill group of R1, R2.... The slab 1 is then rolled to have target dimensions, that is, the target slab width and slab thickness on the outlet side of a rough rolling mill group 2. Crops of the top and rear end parts of the slab 1 after rolling are cut by a crop shear CS. In that case, the relation between an edge draft amount by the edging press P and an edge draft amount by the vertical rolling mill VSB is properly changed and adjusted. The crop amount of the slab rear end part is brought to be about 0 mm by bringing the ratio of (an edge draft amount by the vertical mil)/(the total edge draft amount of an amount by the edging press P and an amount by the vertical mill) to be about 0.09.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to width sizing of a hot slab, that is, a method for adjusting the width of a hot slab to a predetermined width. This invention relates to a method for minimizing crop loss when sizing by width pressing over the entire length.

[Prior art]

A large reduction technology for hot slabs has been developed as a technology for synchronizing the continuous casting process and the hot rolling process for continuously cast slabs. This means that when manufacturing slabs of different widths, the casting width in continuous casting was conventionally changed by using a variable casting width mold or replacing the mold, but without changing the casting width. This is a method of obtaining a slab of a desired width by pressing down and sizing the hot slab in the width direction after casting.

By the way, width sizing methods for hot slabs are broadly classified into vertical rolling methods and press width reduction methods.

Among these methods, an example of a press width reduction method for reducing the entire length of a hot slab using a pair of press tools is disclosed in JP-A-53-26759.

This invention is a method for significantly reducing a hot slab by installing a width press device in a group of hot rough rolling mills.

However, when the hot section slab is significantly reduced using a width press device, tongue-shaped crops occur at the leading and trailing ends of the hot section 1, as shown in Figure 2, resulting in a significant drop in product yield. . Note that the protruding length of the tongue-shaped end of the hot slab is called crop length l, and in this case, it is a positive value.

On the other hand, in order to solve the above-mentioned problems of the invention, the invention disclosed in, for example, Japanese Patent Application Laid-Open No. 166101/1983 has been proposed. In this invention, the front and rear ends of the hot slab 1 are preformed in advance using a width press device, and then the entire length of the hot slab 1 is reduced in width. That is, the tongue-shaped crop that is said to occur in the invention of JP-A-53-26759 mentioned above can be generated by previously deforming it in the opposite direction, that is, by giving it a fintail-like deformation as shown in FIG. This is what we try to avoid. Note that the crop length l in this case is a negative value.

C Problems to be Solved by the Invention] However, since the width reduction amount of the vertical rolling mill of the conventional rolling mill group is changed and adjusted to various values depending on the rolling conditions, preforming using only the above-mentioned width pressing device is not possible. It was found that this was insufficient to minimize crop losses. That is, for example, when the width reduction amount of the vertical rolling mill is relatively small, a tongue-like crop occurs, and conversely, when the width reduction amount of the vertical rolling mill is relatively large, as shown in FIG. This means that a fintail-like crop occurs, and a decrease in yield is unavoidable.

In addition, since unnecessary rosso is usually cut off by a crop shear on the exit side of the rough rolling mill group, the cropping at the rough rolling mill group is cut in order to minimize the crop loss on the exit side of the rough rolling mill group. It is necessary to predict the occurrence situation and determine the amount of preforming by the width press device. However, in the past, the width reduction amount of each vertical rolling mill in the roughing mill group was set to various values depending on the rolling conditions, so it was quite difficult to predict crop changes in the roughing mill group with high accuracy. It is. Therefore, even if highly accurate preforming is performed using a width press device, there is a limit to minimizing the amount of crop generated on the exit side of the roughing mill group.

The present invention was made in view of these circumstances, and
The ratio between the amount of width reduction of the hot slab by the width press equipment and the amount of width reduction of the hot slab by the vertical rolling mill located at the most upstream of the rough rolling mill group, that is, the position closest to the width press equipment, is determined depending on the rolling conditions. The purpose of the present invention is to provide a method for sizing the width of a hot slab that can reduce crop loss as much as possible by changing and adjusting the width of the hot slab.

Furthermore, in the present invention, cropping on the exit side of the rough rolling mill group is minimized by maintaining the width reduction amount of the hot slab by the other vertical rolling mills other than the most upstream of the rough rolling mill group at a constant value. The purpose of the present invention is to provide a width sizing method that facilitates control.

[Means for solving problems]

In the present invention, the amount of width reduction by the width press device and the amount of width reduction by the width press are calculated based on various rolling conditions such as slab width, slab thickness, target slab width at the exit side of the rough rolling mill group, the same thickness, and amount of width reduction in each rolling mill. When determining the amount of width reduction by the most upstream vertical rolling mill of the roughing mill group, the ratio between the two is determined so as to minimize the crop loss on the exit side of the roughing mill group.

The present invention comprises a width press device that rolls down a hot slab in the width direction using a pair of press tools, a vertical rolling mill disposed at the most upstream position on the side of the width press device, and a plurality of vertical rolling mills in the downstream direction. In a method of sizing the width of a hot slab using a rough rolling mill group in which horizontal rolling mills and horizontal rolling mills are arranged alternately,
In order to make the crop length of the downstream end of the hot slab zero depending on the rolling conditions, the amount of width reduction of the hot slab by the width press device and the width reduction by the vertical rolling mill at the most upstream position of the rough rolling mill group are determined. It is characterized by changing and adjusting the ratio to the amount.

[Effect]

In the present invention, the tongue-shaped crop produced by the width press device and the fintail-shaped crop produced by the vertical rolling mill at the most upstream side of the roughing mill group act to cancel each other out.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof.

FIG. 4 is a schematic plan view showing a width press device and a group of rough rolling mills used to carry out the hot slab width sizing method according to the present invention.

In the figure, P is a width press device, νSB, and R2, E3 to E6 are a group of vertical rolling mills. are arranged in order.

In addition, R1, R2-R6 in the figure is a horizontal rolling mill group, and the first horizontal rolling mill R is located downstream of the most upstream vertical rolling mill 1/SR.
2, a second vertical rolling mill E2 is located downstream of this first horizontal rolling mill R1, and so on, a vertical rolling mill νSB.

IE2. R3... and horizontal rolling mR1, R2, R3.
...are arranged alternately. Note that the vertical rolling mill groups VSB, E2. R3... and horizontal rolling mill group +21. R2, l? 3... Rough rolling mill group 2
is configured.

Furthermore, in the figure, C5 is a crop shear, which is arranged to cut crops at the front and rear ends of the hot slab 1.

In such a device, a hot slab L cast by a continuous casting device or the like is first significantly rolled down by a width press device P, and then passed through vertical rolling mill groups VSB, E2. R3 . . . and the horizontal rolling mill groups R1, R2 . Then, crops at the leading and trailing ends of the hot slab 1 after rolling are cut by a crop shear C3.

In addition, the inventors of the present application have determined that the scale of the actual device as described above is 1/1.
Various experiments were conducted using the model No. 12.5 as described below.

FIG. 5 shows the shape of the press tool 20.20 of the width press device P used in the experiment, in which the length Ll of the parallel portion 21 is 50 mm, and the length L2 of the tapered portion 22 is 75 mm.

The taper angle θ is 15°. Then, the hot slab 1 is placed between the press tools 20 and 20 by moving the two press tools 20 and 20 toward and away from each other while maintaining their respective parallel portions 21 and 21 in a parallel state. Perform width reduction.

Further, FIG. 6 is a schematic diagram showing the procedure of width reduction processing by the width press device P. That is, as shown in FIG. 6 fa),
After preforming the tip 11 of the hot slab I with the tapered parts 22 and 22 of the press tools 20, 20, the hot slab I is width-pressed with a constant feed amount f, as shown in Fig. 6 fb). While feeding the hot slab 1 to the device P, the width reduction of the intermediate portion 12 of the hot slab 1 is repeated. Next, as shown in FIG. 6 (el), the width reduction of the middle part 12 of the hot slab 1 is temporarily interrupted, and the rear end part 13 is preformed with the taper part 22.22 of the press tool 20°20. Thereafter, width reduction is performed while feeding the intermediate portion 12 of the preformed hot slab 1 from the rear end portion 13 side to the width press device P again at a constant feed amount f.

Note that the preforming is performed at the tapered part 22° 22 of the press tool 20.20 while the hot slab 1 is
This is because the degree of generation of tongue-like crops is smaller when width reduction is performed at the tapered portion 22.22 than when width reduction is performed at the tip and rear end portions 11.12.

The slab used in the experiment had a thickness of 220 mm. Width is 128■
They are 210 dragons and 1600 dragons respectively in terms of actual machines.
Corresponds to wealth ■. Further, the feed lr is set at 32 am, which corresponds to 400 am in terms of the actual machine.

In addition, vertical rolling mill groups VSB, 1E2. The roll diameter of R3... was 80mm, and the roll diameter of horizontal rolling mill groups R1, R2... was 100mm.

By the way, when the width of the hot slab 1 is reduced by the width press device P, the thickness of the hot slab 1 increases. More specifically, the intermediate portion in the board width direction is raised. When the hot slab 1 in such a state is horizontally rolled down again to the original thickness using the horizontal rolling mill R1, the width of the hot slab 1 is expanded.

Here, the difference between the initial width of the hot slab l and the width after horizontal rolling is called the width adjustment amount, and the ratio between this width adjustment amount and the amount of width reduction by the width press device P is the difference between the initial width of the hot slab l and the width after horizontal rolling. This is called width adjustment efficiency. Note that the efficiency of adjusting the strip width by the width press device P is usually higher than the efficiency of adjusting the strip width by the vertical rolling mill VSB.

FIG. 1 is a graph showing the results of an experiment conducted by the inventors of the present invention. Specifically, the width of the strip is adjusted between the width press device P and the vertical rolling mill VSB so that the amount of strip width adjustment is constant. The rear end portion 13 of the hot slab 1 after rolling by the horizontal rolling mill R1 when the ratio of the width rolling amount by the width pressing device P and the width rolling amount by the vertical rolling mill VSB is changed in consideration of efficiency. The crop length l is shown.

Here, the crop length l is a positive value in the case of a tongue-shaped crop (the slab end protrudes) as shown in FIG. Cases where the area is indented are shown as negative values. In addition, the ratio of the press width reduction amount by the width press device P and the rolling width reduction amount by the vertical rolling mill vsB shall be determined by the width reduction amount by the vertical rolling mill, the total width reduction amount of the width pressing and the vertical rolling. .

According to FIG. 1, that is, the experimental results by the inventors of the present application, when the width reduction amount by the vertical rolling mill VSB is 0, that is, when the width reduction is performed only by the width press, the tongue as shown in FIG. The result was that a crop of the form occurred. Specifically, when the width reduction amount by the vertical rolling mill VSB is O, the value of the above formula is 0, and correspondingly, at the 0 position on the horizontal axis in Fig. 1, the crop length of the rear end of the slab is 1 is slightly over 2 cranes, indicating a tongue-like cropped shape. Then, as the width reduction amount by the vertical rolling mill VSB is increased, the crop length l of the rear end of the slab becomes 2B as described above.
It gradually decreases from 0 to 0, and then the value of the above formula becomes 0.
By age 20, it has changed to about -2 cranes. That is, it was found that as the width reduction amount by vertical rolling was increased, the crop shape at the rear end of the slab changed from a tongue shape to a fintail shape.

In other words, if the required plate width adjustment amount between the vertical rolling mill VSB and the rough rolling mill Gunsan side is given, the crop shape of the rear end of the slab can be arbitrarily controlled based on the above formula. It means that. In other words, if the relationship between the width reduction amount by the width press and the width reduction amount by the vertical rolling is changed and adjusted as appropriate so that the value of the above formula becomes about 0.09, the crop length l of the rear end of the slab can be adjusted. This means that it can be reduced to almost 0 ■.

Next, the inventors of the present application conducted a model experiment regarding the change in crop length l during rough rolling within the rough rolling mill group 2, that is, the first vertical rolling mill VSB and the first horizontal rolling fiR1 and subsequent ones. The results are shown in the graph of FIG.

The graph in FIG. 7 shows that on the exit side of the first horizontal rolling mill R1,
That is, the crop length l of the rear end of the slab after horizontal rolling is performed only in the first horizontal rolling mill R1 and the output side of the rough rolling mill group 2,
That is, it shows the relationship with the crop length l of the rear end of the slab after horizontal rolling is performed in all the horizontal rolling mills R1, R2, . . . . Also, A and B in Figure 7.

C is the crop length of the rear end of the slab when the width reduction amount by the vertical rolling mill groups VSB, E2°R3, etc. of the rough rolling mill group is changed, respectively! , A indicates the case where the width reduction amount is relatively large, B indicates the case where it is medium, and C indicates the case where it is relatively small.

From this Fig. 7, vertical rolling mill group VSB, [2, R3,
It is shown that when the width reduction amount of . This means that when determining the ratio of the width reduction between the width press P and the most upstream vertical rolling 1131VsB in order to minimize the crop length l of the rear end of the slab on the rough rolling machine Gunsan side, as described above, Most upstream vertical rolling 11! This means that it is very difficult to predict the crop length l on the rough rolling mill Gunsan side when the rolling conditions in each rolling mill after lv s a change.

Therefore, each vertical rolling mill E2 of the rough rolling mill group except the most upstream vertical rolling mill VSB. I! 3. The width reduction amount by... is determined by each vertical rolling mill E2. If R3... is maintained constant, the crop length l of the slab on the roughing mill Gunsan side
Accurate predictions become possible very easily. That is, in the actual rolling process, if the width reduction amount of the hot slab 1 by the most upstream vertical rolling mill νSB is kept constant (each vertical rolling mill 82, R3... The crop length l of the hot slab 1 can be controlled with high precision.

Note that the above-mentioned fact applies not only to the control of the crop length E but also to the prediction of the board width.

〔effect〕

As detailed above, according to the present invention, even when a hot slab is significantly rolled down using a width press device, the crop loss at the rear end of the slab on the roughing mill exit side can be minimized as much as possible. It becomes possible. Therefore, it is possible to significantly improve the yield when performing width sizing of slabs obtained by continuous casting.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between the crop length and the ratio of the width reduction amount by width press to the width reduction amount by vertical rolling to explain the basic principle of the present invention, and Fig. 2 shows the relationship between crop length. FIG. 3 is a schematic diagram showing a Finster-like cropped shape, and FIG. 4 is a schematic plan view showing the configuration of a width press device and a rough rolling mill group consisting of a vertical rolling mill group and a horizontal rolling mill group. Figure 5 is a schematic diagram showing the shape of the press tool of the width press device, Figure 6 (al, (bl, tc+)
Figure 7 is a schematic diagram showing the process of width reduction of hot slabs using width press equipment, and Figure 7 shows the crop length at the exit side of the horizontal rolling mill next to the most upstream vertical rolling mill and the crop length at the exit side of the rough rolling mill group. It is a graph showing the relationship with crop length. 1... Hot slab 2... Rough rolling mill group 20.
...Press tool P...Width press device VSB...
・Upstream vertical pressure i! Machines E2-E6...Vertical rolling mill P1-R6...Horizontal rolling mill! ... Long Crop Patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney Noboru Kono No. 1 Note 2. 3rd same P? ' 4th figure 5 figure (tll bl (C) 纂 G 7 口

Claims (1)

[Claims] 1. A width press device that rolls down a hot slab in the width direction using a pair of press tools, and a vertical rolling mill arranged at the most upstream position on the side of the width press device, and a plurality of rolling mills in the downstream direction. In the method of sizing the width of a hot slab using a rough rolling mill group in which vertical rolling mills and horizontal rolling mills are arranged alternately, in order to make the crop length of the downstream end of the hot slab caused by the rolling conditions zero, A method for sizing the width of a hot slab, comprising changing and adjusting a ratio between the amount of width reduction of the hot slab by a width press device and the amount of width reduction by a vertical rolling mill at the most upstream position of the rough rolling mill group. 2. The width of the hot slab according to claim 1, in which the amount of width reduction of the hot slab by each vertical rolling mill other than the vertical rolling mill at the most upstream position in the group of rough rolling mills is maintained constant. Sizing method.