JPS6358046B2 - - Google Patents

Description

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

Generally, in thick plate rolling, continuous casting slabs or blooming slabs are first subjected to 1 to 3 passes of forming rolling to adjust the thickness of the slab, and then this is
After turning 90 degrees and performing tentering rolling the required number of passes to obtain the desired sheet width, the sheet is further turned 90 degrees and returned to the original direction, and finish rolling is performed the required number of passes to achieve the desired width. We obtain steel plates of various thicknesses, widths, and lengths.

In thick plate rolling, it is very effective to improve the yield by producing a steel plate 1 that does not require edge cutting (Fig. 1). Edge cross-sectional shape 2
(folding) and 2' (bulge), the edge cross sections on both sides must be rectangular.

For this purpose, as shown in FIG. 3, it is necessary to repeatedly perform horizontal rolling and edge rolling using the horizontal roll 3 of the flat roll and the edger roll 4 during the finish rolling stage in order to manufacture the steel plate 1 with a rectangular edge cross section. This is the basic method.

However, depending mainly on the thick material and the rolling conditions such as light reduction, overlap 5 (Fig. 4) may occur during tentering rolling, or double bulges may occur during L direction rolling in each step of forming or finishing rolling. Figure 5 a) may occur.

That is, during tentering rolling, as shown in FIG.
Since the metal flow in the rolling direction differs in the thickness direction,
An overlap 5 occurs at the leading and trailing ends of the rolling process (that is, at both edges of the finished product). This overlap 5
corresponds to the width end of the product during finish rolling,
Fold 2 (second
Figure) may remain inside.

As a countermeasure to this problem, a method of chamfering the corners of the slab in the forming rolling stage before tentering rolling is proposed in Japanese Patent Publication No. 54-7504, but there are cases where the double bulge shape is not completely eliminated in finishing rolling. Also, due to the edger opening, it is not possible to reduce the opening below a certain width, so during forming rolling, it may not be possible to perform chamfer rolling on a slab width that is below this minimum opening.

In the former case, if there is a limit to the chamfering amount a (see Figure 6) due to the bus schedule of edge rolling, although the crease will disappear when the tentering is completed, the double bulge shape may remain, and furthermore, the finishing Even in rolling, when only a particularly light rolling reduction can be achieved, a double bulge shape 7 is formed as shown in FIG. Of course, if it is not possible to chamfer before rolling for tentering 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 etched with a flat roll, the metal in the double bulge part flows in the thickness direction on both the front and back sides. Metal flow (arrow) also occurs in the central part in the thickness direction, and as a result, there are problems such as depressions 10 being formed in areas that are not rolled down by the rolls, and folds remaining. In addition, by flat-edging, it is possible to eliminate the recesses by increasing the reduction amount over the entire thickness direction and applying sufficient reduction, but at the stage of finish rolling, the plate thickness is becoming thinner, so it is not possible to eliminate the depressions. 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.

The present inventors calculated the metal flow in the cross section when flat-edging was applied in the finish rolling process to each sheet material having the above-mentioned double bulge-like and single-bulge-like end shapes (Fig. 5). As a result of comparative studies, it was found 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, the end shape before flat edging When the part shape is a single bulge, as shown in Figure 9, the metal flow (arrow) at the end due to flat etching occurs only in the center direction of the board width and the front and back sides of the thickness, whereas in the case of a double bulge, It has been found that since there is no metal flow toward the center in the thickness direction, no folding occurs at all, and no depressions occur. It has also been 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 to approximate a single-bulge shape, and then flat-edged to avoid folding. The present invention was created based on this knowledge.

That is, the gist of the present invention is that in the process of manufacturing a steel plate with a rectangular cross section by repeating horizontal rolling and edging rolling using a horizontal rolling mill with flat rolls and an edger rolling mill during finishing rolling of a thick plate, The method of rolling a thick plate is characterized in that, prior to rolling, the edge of the side edge of the plate is chamfered using a caliber roll having a dial hole type, and then edge rolling is performed.

Here, as the vertical rolls of the edger rolling mill, a pair of left and right rolls are provided with a flat part and a caliber part and are raised and lowered to be used for different purposes.

For preforming by chamfering the edge of the plate side using the caliber part of this vertical roll, for example, as shown in FIG.
Use. Alternatively, the horizontal rolling mill may be arranged as an edger rolling mill to perform horizontal rolling after preforming and then flat-edging.
Further, the preform etching may be performed multiple times within the range possible, if necessary.

Examples of the present invention are shown below.

Case 1 First, as shown in Fig. 10, a plate material with a thickness H = 32 mm and a single bulging amount sb = 6 mm is flat-edged with an edging amount e = 9 mm in the finish rolling process, resulting in folding. did not occur at all.

Case 2 On the other hand, as shown in Fig. 11, flat etching with an edging amount e = 10 mm was performed in the same process on a plate material with a thickness H = 32 mm and a double bulging amount db = 4 mm. horizontal direction d=0.7mm,
A dent of 3 mm in the thickness direction remained. Furthermore, even when etching was performed on this, the depression did not disappear.

Case 3 Next, according to the present invention, a plate material having a double bulge-like end shape similar to that of Case 2 is rolled using a vertical roll having a caliber with a chamfer angle θ=60°, as shown in FIG. 12A. 8 was used to perform preforming with a chamfer amount a = 7 mm, and then flat etching was performed with an edging amount e = 6 mm as shown in Fig. It was rolled down over a long period of time, and no defects such as dents occurred.

In addition, preform rolling is carried out after finishing tentering rolling.
Finish rolling after turning 90 degrees may be carried out at any stage before the final flat rolling by the edger, but if carried out too late, double bulges may grow or double bulges may occur due to the plate thickness. Since the amount ratio increases, the effect of chamfering becomes difficult to exhibit, and the plate thickness becomes thinner, making buckling more likely to occur. Therefore, it is preferable to carry out the chamfering 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.

As is clear from the above explanation, the present invention performs flat etching after preforming the side edge of the steel plate in the finish rolling process, so the shape of the edge of the steel plate can be corrected well. This has great effects such as omitting the cutting process of the side edges and improving yield.

[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.
Fig. 2 is a diagram showing the cross-sectional shape of a rolled steel plate normally obtained by the conventional method (partly only the edges); Fig. 3 is a schematic explanatory diagram showing a finishing rolling mill having horizontal rolls and vertical rolls; Figure 4 is a diagram explaining the situation in which front and rear end overlap occurs in a steel plate due to horizontal rolling, and Figure 5 is a diagram showing the cross-sectional shape of the end of the steel plate, where A is a double bulge shape and B is a single bulge shape. Fig. 6 is a schematic explanatory diagram showing the chamfering rolling situation during forming rolling with edger rolls, and Fig. 7 shows the double bulge shape of the edge of the steel plate when horizontal rolling is performed with a small reduction ratio. FIG. 8 is an explanatory diagram illustrating a situation in which a rolled material having a double bulge-like end shape is flat-edged, and FIG.
The figure is a diagram illustrating the metal flow situation at the end cross section when flat-edging a rolling mill with a single-bulge-like end shape. An explanatory diagram showing a comparative example (one case) of
Fig. 11 is an explanatory diagram showing a comparative example (case 2) in which a rolled material with a double bulge-like end shape is flat-edged, and Fig. 12 is a rolled material similar to the rolled material shown in Fig. 11 with chamfering. FIG. 7 is an explanatory diagram showing an example (case 3) in which rolling is performed and then flat edged. 1... Steel plate that does not require edge cutting, 2... Folding, 3...
Horizontal roll, 4...Vertical roll (edger roll), 5...Overlap, 6...Caliber portion of vertical roll, 7...Double bulge, 8...Vertical roll.

Claims (1)

[Scope of Claims] 1. In the process of manufacturing a steel plate with a rectangular cross section by repeating horizontal rolling and edge rolling using a horizontal rolling mill and an edger rolling machine having flat rolls during finish rolling of a thick plate, prior to edge rolling, a diamond A thick plate rolling method characterized by performing edge rolling after chamfering the edge of the side edge of the plate using a caliber roll with grooves.