JPH0230301A - Method for sizing width of slab - Google Patents

Abstract

PURPOSE:To improve the sheet width accuracy of a rolled stock and the yield by concretely finding an optimum press width drafting amount and an optimum edging width drafting amount when a target sheet width of a slab and a target crop length are given. CONSTITUTION:A width press 3 provided with press heads 2, 2 having respective faces whose distance between them is gradually narrowed in the width direction of a slab 1 toward the transfer direction of the slab 1 subjected to width sizing is installed in the upstream side of a rolling line. A 1st edging mill 4 provided with vertical two rolls is installed in the downstream side in the transfer direction. A 1st horizontal mill 5 having two horizontal rolls, a 2nd edging mill 6 and a 2nd horizontal mill 7 are installed in the downstream side of the mill 4. An equation 1 estimating a sheet width changing amount deltaWP and a crop length changing amount lP at horizontal rolling after width pressing and an equation 2 estimating an sheet width changing amount deltaWV and an crop length changing amount lV at horizontal rolling after edging rolling are used and doubled to find a press width drafting amount WP and an edging drafting amount WV by use of an equation 3 so that a sheet width and a crop length on the outlet side of the horizontal rolling equal to prescribed target values, respectively.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for sizing the width of a slab, and more specifically, the present invention relates to a method for sizing the width of a slab. This invention relates to a slab width sizing method to enable yield rolling.

[Conventional technology]

Slab width sizing methods are broadly divided into the edging rolling method and the width pressing method. Fig. 5 is a schematic perspective view showing the cross section of the slab after width sizing, Fig. 5(a) shows the edging rolling method, and Fig. 5(b) shows the width pressing method. . Fig. 6 is a plan view showing the crop shape of each slab, Fig. 6(a) shows an edging rolling method in which horizontal rolling is performed after edging rolling, and Fig. 6(b) shows a plan view showing the shape of the crop of each slab. This shows the width press method that performs horizontal rolling.

Further, 1 indicates the slab after width sizing, 1' indicates the rear edge in the longitudinal direction of the slab 1 after width pressing, and the white arrow indicates the flow direction of the slab 1.

Among these, the edging rolling method has high production efficiency, but has the following problems. That is, when the slab 1 is rolled in the width direction by an edger roll, the shape shown in FIG.
), the plate thickness near both ends in the width direction is considerably larger than that at the center, resulting in a so-called dogbone-shaped cross section.

Furthermore, at both longitudinal ends of the slab l, the constraint conditions for the slab l in the width direction are different from those at the center, so both ends in the width direction are stretched in the longitudinal direction at both longitudinal ends of the slab 1, as shown in FIG. The result is a fishtail-like crop shape as shown in a).

Further, when the slab 1 having a dogbone-shaped cross section as shown in FIG. bring about

The fishtail-like crop shape generated by such an edge rolling method increases in proportion to the amount of width reduction in the edge rolling process, resulting in a significant decrease in yield due to crop loss.

On the other hand, although the width pressing method is aimed at solving the problems of the above-mentioned edging rolling method, it still has various problems.

In the width pressing method, the deformation of the slab 1 extends deeper into the width direction of the slab 1, that is, to the center of the width direction of the slab 1, than in the case of the edge rolling method, so even when a large width reduction is performed, the slab 1 deforms. As shown in FIG. 5(b), the cross-sectional shape of the slab 1 is a simple mountain shape with a raised central part in the width direction in the entire longitudinal direction of the slab except for the front and rear ends of the slab. Therefore, even if horizontal rolling is performed thereafter, the amount of elongation in the width direction is much smaller than in the edge rolling method.

However, such a width pressing method has lower production efficiency than the edging rolling method, and when width pressing is performed continuously in one direction from one longitudinal end of the slab 1 to the other end, As shown in FIG. 6(b), the rear edge 1' of the slab 1 in the longitudinal direction is deformed into a tongue-like cropped shape in which the central part in the width direction protrudes further in the longitudinal direction, which causes a decrease in yield. A problem arises.

Therefore, various proposals have been made to alleviate the above-mentioned problems found in the relatively easy width pressing method as a method for sizing the width of the slab 1.

For example, in Japanese Patent Application Laid-Open No. 60-203303, after performing width pressing sequentially from one end in the longitudinal direction to the middle part of the slab,
- A method is described in which this operation is temporarily interrupted, the other end of the slab is preformed, and then the width is pressed again from the intermediate part toward the other end. This method attempts to suppress the tongue-shaped deformation of the rear end due to the width brace by preforming the longitudinal rear end of the slab.

However, since the above method requires extra time to feed the slab, the production efficiency, which is already low compared to the edge rolling method, is further reduced.

Therefore, the lever press method has been proposed as a method to improve the above method. In this method, the width of the slab is pressed sequentially from one end in the longitudinal direction to the middle part, then the slab is fed blankly, and then the width is pressed in the reverse direction from the other end to the middle part, resulting in the entire length of the slab. This completes the width press.

However, even with the lever press method, the effect of improving the tongue-shaped crop is not sufficient, and like the preforming method, there is a problem that the production efficiency is lower than that of the edge rolling method.

Various measures have been proposed to improve the cross-jib shape in addition to the two methods mentioned above, but one of the most effective measures is to perform edge rolling after width pressing. .

One of these methods is a method that skillfully combines both the above-described crop shape change of the slab during width pressing alone and edge rolling alone, that is, tongue-like deformation due to width press and fishtail-like deformation due to edge rolling.
Using this method has a sufficient effect on improving the tongue-shaped crop shape at the rear end when using a one-way press, and is also superior in terms of production efficiency compared to other width sizing methods that use only a width press. .

Another method is the method disclosed in Japanese Unexamined Patent Publication No. 60-203304, and its gist is that after pressing the slab from one end in the longitudinal direction to the vicinity of the other end to a predetermined width, the remaining part is pressed. Press the width so that it is slightly wider than the specified width,
By performing edge rolling on this portion, the amount of change in crop length is controlled and the yield is improved.

[Problem to be solved by the invention]

However, in the case of the former method, there is a problem in how to determine the press width reduction amount and the edging width reduction amount for the given target plate width and target crop length, and the former method However, there is no mention of how to specifically determine the optimum press width reduction amount and the optimum edging width reduction amount.

In addition, in the case of the latter method, there is usually a relationship between the strip width adjustment efficiency η by width press and the strip width adjustment efficiency η9 by edge rolling as η,〉η9, so the amount of press width reduction and the amount of edge width reduction are If the ratio is not constant in the longitudinal direction of the slab, the plate width may fluctuate in the longitudinal direction of the slab due to the difference in plate width adjustment efficiency when the subsequent horizontal rolling is performed, and the press width reduction amount may be changed midway through. There have been problems such as a decrease in production efficiency due to this and an increase in the cost of press equipment to enable midway changes in press width reduction.

On the other hand, in order to find the optimal press width reduction amount and optimal edging width reduction amount, we need to know the amount of change in the width of the rolled material and the crop length when width sizing of the slab is performed using arbitrary press width reduction amounts and edging width reduction amounts. It is necessary to specifically predict the amount of change. Therefore, we considered how to concretely predict the amount of change in width of the flat plate and the amount of change in crop length. ■ Changes in shape of rolled material due to width sizing were obtained by horizontally rolling a rectangular cross-section slab after width pressing. It can be determined by superimposing the shape change when the rectangular cross-sectional slab is horizontally rolled after edge rolling.

■ It was found that the change in crop shape was significantly larger at the rear end of the slab than at the leading end in both width pressing and edge rolling.

The present invention has been developed in view of the above circumstances, and allows for easy rolling by specifically determining the optimum press width reduction amount and the optimum edging width reduction amount when the target plate width and target crop length of the slab are given. It is an object of the present invention to provide a method for sizing the width of a slab, which makes it possible to increase the accuracy of the width of the material and to improve the yield.

[Means for Solving the Problems] A method for sizing the width of a slab according to the present invention is a method for sizing the width of a slab in which the slab is width-pressed, then edge-rolled, and then horizontally rolled. A formula for estimating the width change and crop length change from before width pressing, and the width change and crop length change from before edge rolling of the slab when the slab is horizontally rolled after edge rolling. Using the formula for estimating the amount, find the combination of press width reduction amount and edging width reduction amount that will make the plate width and crop length after width pressing, edge rolling, and horizontal rolling of the slab to a predetermined target value. , is characterized in that width pressing and edge rolling are performed based on this.

[Effect]

In the method of the present invention, a formula for estimating the width change and crop length change when horizontally rolled after width pressing, and a formula for estimating the width change and crop length change when horizontally rolled after edge rolling. and superimpose them so that the strip width and crop length on the exit side of horizontal rolling after width pressing and edge rolling become predetermined target values.
The combination of the press width reduction amount and the edging width reduction amount is determined, and the width of the slab is sized using them.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The slab width sizing method according to the present invention (hereinafter referred to as the method of the present invention) will be described in detail below with reference to drawings showing examples thereof.

FIG. 1 is a schematic plan view showing the rolling line of the method of the present invention, where l is a slab having a rectangular cross section and whose width is sized. A width press 3 with opposing press heads 2.2 having a surface that gradually narrows in the width direction is provided upstream of the rolling line. On the downstream side in the flow direction, there is provided a first rolling mill 4 equipped with two upright rolls, and on the downstream side, a first horizontal rolling mill 5 equipped with two horizontal rolls, and a second rolling mill 4 equipped with two horizontal rolls. Horizontal rolling mills such as a rolling mill 6 and a second horizontal rolling mill 7 and an edging mill are arranged alternately.

FIG. 2(a) is a schematic diagram showing the specifications of the width press, and FIG. 2(b) is a schematic diagram showing the deformation of the slab over time during the width press. As shown in the figure, the initial feed position Wfa, the radial angle θ to the press, the feed amount f,
Width pressing is performed by determining the specifications of the width pressing 3, such as the width pressing amount ΔWP and the initial slab width W0. Further, as shown in FIG. 2(b), when the width press is used alone, the rear end of the slab becomes fishtail-shaped. Furthermore, Table 1 shows the specifications of the rolling line of this example, which is 1/12th of the actual machine.
It shows the case where a 5 scale miniature slab is used and the case where it is converted into an actual machine.

A method for determining the optimum press width reduction amount and the optimum edging width reduction amount, which is the gist of the present invention, will be explained in Table 1 and below by giving the target board width and target crop length.

In order to predict the shape change of the slab l whose width has been sized on the rolling line shown in FIG. A method of overlapping was used.

Figure 3 shows the rear end crop length l on the exit side of the radial press and on the exit side of the horizontal rolling when the thickened part of the slab is horizontally rolled after width pressing of slabs of various widths. The rear end crop length l is plotted on the axis, and the initial slab width W is plotted on the horizontal axis.
, is taken. Moreover, the broken line shows the rear end crop length after width pressing, and the solid line shows the rear end crop length on the horizontal rolling exit side, respectively. Further, the width press amount ΔW indicates the case of 28 squares.

When predicting the shape change of slab 1 due to width pressing, after width pressing slab 1, horizontal rolling of only the thickened portion caused by width pressing is performed, and the width change δW and crop length change of slab 1 are calculated. The amount Δ2F is predicted. This is because when slabs of various widths are pressed horizontally and the raised thickness portion is horizontally rolled, the rear end crop length l of the slab 1 changes as shown in FIG. 3 due to the influence of metal flow in the raised portion.

An example of a prediction formula obtained by regression based on the results of various experiments is shown below.

δWP=η2・ΔW.

...(2) η, nibless width adjustment efficiency WOP s Slab width before width pressing (usually initial slab width WO) When predicting the shape change of slab 1 due to etching rolling, use the same method as in the case of width pressing described above. , the width change amount δW of the slab l when only the thickened portion caused by the edge rolling is horizontally rolled.

and crop length change amount Δ2v.

An example of a prediction formula obtained by regression based on the results of various experiments is shown below.

δWv = η9 ・ΔWv (1) ΔWv: Edging width reduction amount (difficult) Ho: Slab thickness before edging rolling (ffl) WO
V: Slab width (Inl) before edging rolling
: Roll diameter for edging rolling (fllll) ηV
: Edging width adjustment efficiency Next, using equations (1) to (4) above, the data tested on the rolling line shown in Fig. 1 is regressed to calculate width brace 3 and 1.
Amount of plate width change δW after horizontal rolling of thickness buildup after width sizing by the edging rolling mill 4 and the first horizontal rolling mill 5
An example of a formula for predicting c and crop length change amount Δ2e is shown below.

Δtzc=i, 004 −ΔN, +0.987 −Δ
j! v ・(s) δWc = 1.004 η, ・ΔWP
+ 0.959 ・η7 ・ΔWv...(6) In equations (5) and (6) above, almost superposition is established between the shape change due to width pressing and the shape change due to edging rolling (each coefficient!= il), which shows that the above idea is correct.

In addition, when performing horizontal thinning rolling that also reduces the thickness of the slab instead of horizontal rolling of only the thickened part, the horizontal thinning rolling is divided into horizontal rolling of only the thickened part and thinning rolling of slab 1. Consider (5) above separately.

It is sufficient to superpose the equation for the shape change due to thinning rolling onto equation (6).

Next, the target board width WA and target crop length l are calculated using the obtained formula.
A is given by the following formula, No Hm"'Δic - (7) Wo WA=
δW C-(S) However, 10 Initial crop length of nislab (usually 0) (7
), (8) By solving equations (5) and (6) for the press width reduction amount ΔW and the edging width reduction amount ΔWv, the given target board width WA and target crop can be determined. The optimum press width reduction amount ΔWP^ and the optimum edging width reduction amount ΔWVa for realizing the length 2A can be determined. At this time, the equations for the two variables, the optimal press width reduction amount ΔW0 and the optimal edging width reduction amount ΔWVA, are two independent equations regarding the plate width and crop length, so the optimal press width reduction amount ΔWPA and the optimal edging width reduction amount ΔWVA The width reduction amount ΔWvA can be uniquely determined.

FIG. 4 is a graph showing the relationship between the amount of edge width reduction when edge rolling is performed after width pressing and the crop length after horizontal rolling of the thickened part, and the solid line indicates the rear end crop length l, The dashed line indicates the tip crop length 17.

Further, the vertical axis shows the crop length, and the horizontal axis shows the cutting width reduction amount ΔWv, and the positive direction of the crop length shows a tongue shape, and the negative direction shows a fishtail shape.

As is clear from the figure, in general, changes in crop shape due to width pressing tend to become tongue-like, and conversely, changes in crop shape due to etching tend to become fin tail-like. Therefore, when they are superimposed, they cancel each other out in terms of crop shape change, so there is a high possibility that a combination solution exists between the optimal press width reduction amount ΔWPA and the optimal edging width reduction amount ΔWVA to set the crop length to O. .

Set the target crop length rA to the rear end crop length 2. The reason given is that the change in crop shape at the tip and rear end of the slab due to width sizing is usually larger at the rear end than at the tip, as shown in Figure 4, and the rear end crop length of 1 m changes the shape of the crop at the tip near ζO. Crop length 2T and rear end crop length l! This is because 1 and 1 substantially match.

Also, target board width WA and target crop length! Regarding the determination of the value of 1, each target value on the rough rolling exit side is estimated based on the value on the finish rolling side, and the target strip width WA is determined based on the target value.
and the target crop length IA.

Regarding the optimum edging width reduction amount ΔWVA, from the point of view of width adjustment efficiency, it is desirable to perform it at a place where the material is thicker. If the optimum edging width reduction amount ΔWVA is larger than the reduction amount ΔW V M A X, even if edge rolling is performed using the maximum edging width reduction amount ΔW In this case, the amount of reduction in the edging width of the second edging rolling mill is further increased, and the change in crop length there is shifted to the fishtail side, as a result,
The target crop length l can be made into a tongue shape.

Next, a comparative experiment between an example and a comparative example conducted to confirm the effects of the method of the present invention will be described.

In this experiment, 270mm thick x 1600mm wide x 80
A carbon steel slab with a length of 00++w was used, and other width sizing conditions were the same as in Table 1. The comparative example shows the case where only width pressing was performed. The results are shown in Table 2.

Table 2 As is clear from Table 2, compared to the comparative example, the shapes of the slabs in Example 1 and Example 2 of the method of the present invention, which were carried out to find the optimum press width reduction amount and the optimum edging width reduction amount, were similar to the target slab shape. The shape, that is, the target plate width and target crop length, are well matched, indicating that the method of the present invention is effective.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to determine the optimum press width reduction amount and the optimum edging width reduction amount for a given target plate width and target crop length, and the plate width after width sizing. It has excellent effects such as improving accuracy and yield.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view showing the rolling line of the method of the present invention;
Figure 2 (a) is a schematic diagram showing the specifications of the width brace;
b) is a schematic diagram showing the deformation of the width press slab over time;
Figure 3 is a graph showing the relationship between the slab width on the exit side of horizontal rolling and the rear end crop length when the slab is horizontally rolled after width pressing, and Figure 4 is a graph showing the relationship between the slab width and rear end crop length when horizontally rolled after edge rolling. Figure 5 is a schematic perspective view showing the cross section of the slab after width press and edge rolling, Figure 6 is the cross section of the slab after width press and edge rolling. It is a top view showing the crop shape of a slab. l...Slab 2...Press head 3...Width press 4...First etching rolling mill 5...First horizontal rolling mill 6...Second etching rolling mill 7...Second Horizontal rolling mill W,...Target strip width l,...Target crop length ΔWP^...Optimum press width reduction amount ΔWVA...Optimum edging width reduction amount Patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney Recruitment for Noboru Kono 5r! j:U! (d) rb) No. 6 criminal condolence (b) No.

Claims (1)

[Claims] 1. In a slab width sizing method that performs edging rolling and horizontal rolling after width pressing, the width of the slab from before the width pressing when the slab is width pressed and then horizontally rolled. A formula for estimating the change amount and crop length change amount, and a formula for estimating the width change amount and crop length change amount from before the edging rolling of the slab when the slab is horizontally rolled after edging rolling. Then, width press the slab, edging roll it, find the combination of press width reduction amount and edging width reduction amount that will make the plate width and crop length after horizontal rolling to the predetermined target values, and perform width pressing and edging based on this. A slab width sizing method characterized by rolling.