JPS59197302A - Rolling method - Google Patents

Abstract

PURPOSE:To prevent a sheet material from producing a torsional deformation and to roll the material into a flat one by regulating the temperature distribution in the width direction of the material to be rolled to a specific one, in rolling the material by a roll cross mill. CONSTITUTION:A material A to be rolled is rolled by a roll cross mill, whose upper and lowr rolls constituted respectively of backup rolls 1, 3 and work rolls 2, 4 are slanted with respect to the advancing direction of the material A and are arranged to intersect with each other. In this case, the rolls 2, 4 can not bite the material A at the next stand or in reverse rolling because of the torsional deformation of material A caused by the mutually reverse offset directions of work rolls 2, 4 and by a shearing force between the material A and the rolls 2, 4. For preventing these troubles, the temperature distribution in the width direction of material A is made approximately uniform or the material A is partially heated or cooled so that the temperature of the central part is lower by about 20 deg.C than that of the end part, before rolling the material A by the roll cross mill.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rolling method for reducing plate threads fLf of a rolled plate when rolling the plate in a roll cross rolling mill.

As shown in Fig. 1, an upper roll 1.2 and a lower roll 3.4 are arranged so as to be inclined with respect to the traveling direction of a plate to be rolled (hereinafter referred to as a plate) A and intersect with each other, and a roll cross for rolling the plate. In the rolling mill, plate A and backup roll 1. An axial force is generated between the rolls and the work rolls 2 and 4 supported at '3. The force acting on the work roll 2.4 is received by a loaf chock (not shown), but the force (shearing force) generated by the plate AK is V! , the shear force directly acts on the plate A, and as a result, the plate Aq comes out of the mill with a twisted plate as shown in FIG. Here, in Figure 2 (a
The torsion shown in ) is a geometric thread that inevitably arises because the offset directions of the upper and lower work rolls 2 and 4 are opposite on the work side and the drive side because the work rolls 2 and 4 are crossed and rolled. The screw fL shown in FIG.

These two types of twisting directions are opposite to each other, and the twisting direction and amount are determined by the difference in the degree of twisting and are influenced by rolling conditions.

However, if plate A is twisted and rolled, plate A will be twisted between the rolls during the next stand or reverse rolling (reverse mill).
The phenomenon of not biting occurs, which has become a problem.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, the present invention aims to provide a rolling method capable of rolling a flat plate without interfering with controlled rolling of the plate threads t''LL produced by roll cross rolling.

The present invention achieves this object by rolling the rolled plate using a roll cross rolling mill in which a pair of work rolls are arranged so as to be inclined with respect to the traveling direction of the rolled plate and cross each other. Partially cooling or heating the rolled plate before rolling so that the temperature distribution in the width direction of the plate is approximately uniform or the temperature at the center of the plate width is lower than the temperature at the edge of the plate width. It is characterized by

Hereinafter, the present invention will be explained from the point of view. When we focused on the thread n of the plate and the temperature during rolling, we found the results shown in Figure 3. Figure 3 shows the relationship between plate thread n ratio Chi/L ('l is plate length, ? is twist amount/plate width) and outlet plate temperature ('l is plate length, ? is twist amount/plate width) in cold measurement results generated in roll cross rolling. In this example, with a work roll diameter of 70-
■Using a board made of 5S41 material at a temperature of 0°C to 400°C, l
Plate thickness X at a speed of Q m/min and cross angles o and f
Board width x length (1) 2 x 200 x 300,
(z) 4 x 100 x 300, (3) 4
Rolling was carried out for three types: x 200 x 300.

In FIG. 3, (1) is represented by O, (2) by ., and (3) all by △. As is clear from Fig. 3, the plate screw 'tL has a close relationship with the outlet plate temperature, and plate screw n occurs when the outlet plate temperature 1 is low, and plate twisting occurs when the outlet plate temperature 1 becomes high. Turns out it doesn't happen.

Figure 4 is a plot of the torsion rate during warm rolling and cold rolling under the same conditions. ) plate screw n and cold plate screw fL are the same rolled material but have different screw threads nfi. That is, in FIG. 4, the plate screw n becomes 1.5 to 2.0 times larger in the cold state than in the warm state. In order to investigate the cause of the difference in the degree of plate twist depending on the temperature, we investigated the plate temperature distribution and found that
The distribution shown in the figure was found. In other words, a normally heated and rolled plate has a temperature difference of 30 to 50°C between the center of the plate width and the edge of the plate, and generally the temperature at the edge of the plate is higher than the temperature at the center of the plate width. ] found to be low.

Therefore, as a result of cross-rolling the plate with a temperature difference in the width direction of the plate and examining the plate twist, the relationship shown in FIG. 6 was obtained. Figure 6 shows the relationship between the temperature difference between the center of the plate width and the edge of the plate and the plate twist rate/L.As the temperature at the edge of the plate becomes lower than that of the center of the plate width, the plate This indicates that the twist is increasing. It has also been found that when the temperature at the edge of the plate width is higher than the temperature at the center of the plate width, the plate twist becomes smaller. Therefore, based on this result, if we consider that the allowable plate screw ratio in actual operation is about -1 If the temperature is about 20° C. or lower, the plate can be twisted to a degree that poses no problem.

The reason why the plate thread n differs due to the plate temperature distribution in the plate width direction is determined by the plate temperature expansion coefficient. In other words, if the temperature at the edges of the strip width is lower than the temperature at the center of the strip width during rolling, the shrinkage of the strip at the center portion of the strip will be larger after cooling, and that at the edges will be smaller. For this reason, a difference occurs in the length of the board in the direction of the length of the board, and as a result, the length of the board at the end of the board becomes longer than the length of the board at the center of the board width, resulting in a state where the end of the board becomes sagging. . On the other hand, in order for the plate to twist and deform, the length of the edge of the plate needs to be longer than the length of the center of the plate width, and when the temperature-related edge elongation occurs as described above, there is no tension at both ends of the plate width. The plate becomes easier to screw.

Conversely, if the temperature at the center of the strip width is smaller than the temperature at the edge of the strip, the amount of shrinkage at the edges of the strip is large and the amount of shrinkage at the center of the machine is small, resulting in a The length of the board at the end of the board width becomes shorter. For this reason, both ends of the plate width are tensed and bent, making it difficult for plate screws fL to occur.

As a result of the above, the amount of plate twist can be corrected by controlling the plate temperature distribution in the plate width direction. Note that FIG. 6 shows the case of thin plate rolling, similar to the cases of FIGS. 3 to 5, but for example, when the thickness is 10
Almost the same tendency occurs in the case of rolling a thick plate such as 0m.

As an example, as shown in FIG. 7, plate temperature distribution A, B, C
FIGS. 8 and 9 show a method of rolling a plate in which the temperature difference between the center of the plate width and the edge of the plate is controlled to within t-20° C., and the plate does not twist even in roll cross rolling.

Figure 8 shows that the center part of the width of the plate A before rolling (approximately 1/3 of the width of the plate) is forcibly cooled with water, air, or a cooling roll It shows how to make the temperature almost the same as that of In addition, in Fig. 9, the heater Z is adjusted so that the temperature at both ends of the board width (approximately 115 in board width from the board end) is approximately the same as the temperature at the center of the board width, contrary to the case of Fig. 8.
This shows a method of forcibly heating the

Furthermore, as the plate is heated or cooled, the temperature at the center of the plate width becomes lower than the temperature at the edge of the plate width. Even if the plate is rolled with a high height, plate screws can be prevented as described above.

In roll cross rolling where the rolling temperature is high, plate screws are generated as shown in Fig. 3, but the above invention is particularly effective in rolling where the plate temperature on the exit side is relatively low. be.

As described above, according to the present invention, the temperature at the edge of the sheet width is changed from the temperature at the center of the sheet width by forcibly cooling or heating the rolled sheet before rolling to make the temperature uniform in the sheet width direction. By increasing the temperature, it is possible to reduce the occurrence of plate twisting during roll cross rolling.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing a roll cross rolling mill, Figure 2 (a
) (b) is a plate screw formed by cross-roll rolling.
Fig. 3 is a graph showing the relationship between the plate screw n produced by roll cross rolling and the outlet plate temperature, and Fig. 4 shows the difference in the amount of plate twist when the plate screw n is hot and cold. Figure 5 is a graph showing the temperature distribution in the width direction of the plate where the plate screw n occurred, Figure 6 is a graph showing the results of cross rolling with a temperature difference intentionally created in the width direction of the plate. , Figure 7 is a graph showing the ideal temperature distribution in the width direction of the plate, and Figures 8 and 9 are plan views showing examples of two directions in which the temperature difference in the width direction of the plate is forcibly controlled. be. In the drawing, 2.4 is a work roll, A is a plate (rolled plate), and X is a cooling roll. This is a Zilt heater. Patent applicant Mitsubishi Heavy Industries, Ltd. Patent attorney Shibe Mitsuishi (and 1 other person) Figure 1 Figure 2 (0) (b)〉/)
2. Banshi Tetsu 19)) Figure 6 Figure 7 Board Width Figure 8 Figure 9

Claims (1)

[Claims] When rolling the plate to be rolled using a roll cross rolling mill in which a pair of work rolls are arranged so as to be inclined with respect to the traveling direction of the plate to be rolled and intersect with each other, temperature distribution in the width direction of the plate to be rolled is carried out. A rolling method characterized in that the plate to be rolled is partially cooled or heated before rolling so that the temperature at the center of the width of the plate is substantially uniform or the temperature at the center of the width of the plate is lower than that at the ends of the width of the plate.