JPS6096304A - Rolling method of thick plate - Google Patents

Abstract

PURPOSE:To correct well the shape of end parts of a steel plate and to obtain a thick plate having rectangularly-edged cross section by performing flat edging after preforming the side-end parts of steel plate at the time of finish rolling the thick plate. CONSTITUTION:At the time of finish rolling a thick plate, a preforming of chamfering quantity (a) is applied for a plate material having single or double-bulged end-shape by using caliber rolls 8. Successively a rolling of edging quantity (e) is performed by using flat rolls. In this way, the edge rolling part is subjected to rolling reduction throughout its whole part, and defects such as recessed cease to generate. Accordingly a cutting work at the side-end part of plate is eliminated and the yield of plate material is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thick plate rolling method, in particular, by improving the finish rolling process in thick plate rolling, so-called thick plate edges with rectangular edges without folds, double bulges, etc. The present invention relates to a method of manufacturing a steel plate that does not require cutting.

In general, in thick plate rolling, a continuous cast slab or a blooming slab is first subjected to 1 to B passes of forming rolling to adjust the thickness of the slab, and then turned 90 degrees to obtain a predetermined plate width. After performing tentering rolling for the required number of passes,
Further, this was turned by 90° and returned to the original direction, and finish rolling was performed a required number of passes to obtain a steel plate having the desired thickness, one width, and one length.

In thick plate rolling, it is very effective to improve the yield by producing a steel plate 1 (Fig. 1) that does not require edge cutting, and the planar shape is made rectangular at the end of rolling. With respect to the edge cross-sectional shape 2.2/ as shown in FIG.

For this purpose, as shown in FIG. 8, it is necessary to repeatedly perform horizontal rolling and edging rolling using flat horizontal rolls 8 and edger rolls 4 in the finishing rolling stage to produce a rectangular edge cross-section steel plate 1. This is the basic method to do so.

However, depending on rolling conditions such as thick wood or light rolling, overlap 5 (Fig. 4) may occur in tenter rolling, and double bulges may occur in L direction rolling in each step of forming or finish rolling (Fig. 5). (b)) may occur.

That is, during tentering rolling, as shown in FIG. 4, since the longitudinal metal flow differs in the thickness direction, an overlap 5 occurs at the rear end of the rolling tip (that is, at both edges of the product). This overlap corresponds to the width end of the product during finish rolling, but in the edging rolling, the overlap corresponds to the fold 2 (second
(Fig.) may remain inside.

As a countermeasure to this problem, a method was developed in which the corners of the slab were chamfered in the forming rolling stage before tentering rolling.
Although it is proposed in Publication No. 504, the double bulge shape may not be completely eliminated by finish rolling, and the opening cannot be reduced below a certain width due to the edger opening, so forming rolling In some cases, it may not be possible to perform chamfer rolling on a slab width that is less than this minimum opening degree.

In the former case, if there is a limit to the amount of chamfering a (see Figure 6) due to the bus schedule for edge rolling, the fold will disappear when the width adjustment is completed, but the double bulge shape may remain. In cases where only a particularly light rolling reduction can be achieved in 1st finish rolling, as shown in Fig. 7,
It becomes a double bulge shape 7. Of course, if chamfering cannot be performed before rolling for width adjustment due to the opening degree of the edger,
Folds and double bulges cannot be eliminated.

As shown in Fig. 8, when the double bulge-shaped width edges caused by tentering rolling and finishing rolling are edged with flat rolls, the metal in the double bulges flows in the thickness direction on both the front and back sides. Metal flow (arrow) also occurs at the center in the thickness direction, and as a result, there are problems such as the formation of depressions 10 in areas that are not rolled down by the rolls, and the formation of folds.

Actually, it would be possible to eliminate the four parts by applying a sufficient reduction by applying a large amount of reduction across the entire thickness direction by flat etching, but at the stage of finish rolling, the plate thickness is becoming thinner, so there is a slight reduction in the thickness. If the pressure is applied too much, problems such as buckling will occur.

It is an object of the present invention to provide a method that can solve these problems and efficiently produce a thick steel plate having a rectangular edge cross section.

(8) The present inventors applied flat etching in the finish rolling process to each sheet material having an inclined double bulge shape and a single bulge shape end shape (Fig. 5). As a result of a comparative study of phthalate flow, it was already mentioned that in the case of a double bulge-like end shape, depressions 10 (Fig. 8) etc. occur due to metal flow, but on the other hand,
If the end shape before flat etching is a single bulge, as shown in Figure 9, the metal flow (arrow) at the end due to flat etching will occur only in the center direction of the plate width and in the front and back sides of the thickness. It has been found that since there is no metal 70- in the center in the thickness direction as in the case of a double bulge, no folding occurs at all and no depressions occur. Also,
It was also found that the single bulge requires less width reduction for the same amount of bulging than the double bulge.

As a result, when flat-edging a double bulge-like end shape in the finish rolling process, it is first preformed so that it resembles a single bulge shape, and then flat-edging results in folding (4). The present invention was devised based on the knowledge that such problems do not occur.

That is, the gist of the present invention is that during top rolling on a YG plate, horizontal rolling and edging rolling are repeated using a horizontal rolling mill and an edging mill having flat rolls, so that the cross section of the side edge of the plate is rectangular. A method for rolling a thick plate, characterized in that, in the process of manufacturing a steel plate, a step of chamfering the edge of the plate with a caliber roll is performed before the edge rolling is performed with the flat roll.

For preforming by chamfering the side edges of the plate with this caliber roll, for example, a caliber-shaped edger roll is suitable as shown in FIG. . Also, depending on the arrangement of the horizontal rolling mill and edger rolling mill, horizontal rolling may be performed after preforming and then flat etching, and if necessary, preforming may be performed multiple times within the possible range. You may go.

Examples of the present invention are shown below.

Case 1 First, as shown in Fig. 10, for a plate with a thickness H = 82mm and a single bulging amount sb = 6w,
As a result of flat etching with an etching amount of 6 = 9 in the finish rolling process, no folding occurred at all.

Case 2 On the other hand, as shown in Fig. 11, flat etching with an edging amount e = 10 was performed in the same process on a plate with a thickness H = 82 mm and a double pulsing amount clb = 4 mm. As a result, depth direction d = 0
．． 7, a depression in the thickness direction w=ami remained. Further, the dents did not disappear even after etching.Case 8 Next, according to the present invention, a plate material having a double pulpin*-like end shape similar to Case 2 was first etched as shown in Fig. 12 (A). As shown in the figure (B), a caliber roll 8 with a chamfer angle θ-60° is used to preform the chamfer amount a=7, and then, as shown in FIG. When etching was carried out, as in Case 1, the entire area of the etching area was reduced, and no defects such as crevices occurred.

Note that preform rolling may be carried out at any stage in finish rolling after finishing tentering rolling and turning 90 degrees, but before final flat rolling by an edger, but it may be carried out at a later point. If this is done, the double bulge will grow and the ratio of double pulsing to the board thickness will increase, making it difficult to achieve the effect of chamfering, and the board thickness will become thinner, making buckling more likely to occur. It is preferable to perform this at an early stage of the finish rolling process.

Of course, it goes without saying that the present invention can also be applied to the rolling of thick steel plates without tentering rolling. Since flat etching is performed after this, the shape of the edge of the steel plate can be corrected well, and the cutting process of the side edge can be omitted and the yield rate can be improved.

(7)

[Brief explanation of the drawing]

Figure 1 is a diagram showing the cross-sectional shape of a steel plate that does not require edge cutting, Figure 2 is a diagram showing the cross-sectional shape of a rolled steel plate normally obtained by the conventional method (partially only the edges), and fa8 diagram is a diagram showing horizontal rolls and vertical rolls. A schematic explanatory diagram showing a finishing rolling mill with a ＼ Fig. 4 is a diagram illustrating the situation in which front and rear end overlap occurs in a steel plate due to horizontal rolling, and Fig. 5 is a diagram showing the cross-sectional shape of the end of the steel plate. ... (a) is a double bulge shape, (b) is a single bulge shape. Figure 6 is a schematic explanatory diagram showing the chamfering rolling situation during forming rolling with edger rolls. Figure 7 is the reduction ratio. An explanatory diagram showing the situation in which the edge shape of a steel plate exhibits a double bulge shape when horizontal rolling is performed with a smaller value. Figure 9, which is a diagram explaining the metal flow situation in cross section, has a single bulge-like end shape (8
) A diagram explaining the metal flow situation at the end cross section when flat-edging a rolling mill. Figure 10 shows the following comparative example (case 1) after flat-edging a rolled material with a single bulge-like end shape. Figure 11 is an explanatory diagram showing a comparative example (Case 2) in which a rolled material with a double bulge end shape was subjected to 7-rat engineing, and Figure 12 is an explanatory diagram showing the rolled material shown in Figure 11 and This is an explanatory diagram showing an example (case 8) in which a similar rolled material is chamfered (a) and then flat-edged (b). Roll 4... Edger roll 5... Overlap 6.8... Chamfering edger roll 7... Double bulge. Figure 12 (a) (b) IQ-

Claims (1)

[Claims] 1. During plate finish rolling, horizontal rolling and edging rolling are repeated using a horizontal rolling mill and an edger rolling machine having flat rolls to produce a steel plate having a rectangular cross section at the plate side end. A thick plate rolling method characterized by carrying out a step of chamfering the side edges of the plate with a caliber roll before performing edge rolling.