JPH0332404A - Method for rolling metallic sheet - Google Patents

Abstract

PURPOSE:To reduce sheet warpage and to improve the yield of products by constituting a transporting path for a material to be rolled in front of a rolling mill tiltably with a horizontal plane and varying the angle at which the material to be rolled advances into the roll gap of the rolling mill. CONSTITUTION:A slab 2 is transported by the tillable transporting path (tilting table) 3 and is rolled by rolling rolls 1. The advance angle of the tilting table 3 can be changed by means of cylinders 4, 5. The warpage of the bar after the rolling is detected by a sensor 6 and the signal thereof is transmitted to a computing element 7. The computing element 7 changes the advance angle by adjusting the cylinders 4, 5 in accordance with the detected information. The element 7 has a learning function and changes the advance angle by overall judging the change in the temp. distribution in the thickness direction of the slab changed by the information on the warpage of the previous bar, the change of the surface condition of the upper and lower rolling rolls, the change of a heating furnace, etc.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method of rolling a metal plate.

[Prior art] In hot rolling of metal sheets, the material to be rolled is transported by a conveyance path and inserted into the gap between the rolls of a rolling mill.9 In normal rolling operations, the material to be rolled is loaded horizontally into the gap between the rolls. However, due to the difference in contact between the upper and lower surfaces of the plate material and the upper and lower roll surfaces, the material to be rolled is bent and deformed in either the up or down direction after rolling. This is caused by differences in surface conditions (e.g., scale adhesion) between the upper and lower surfaces of the rolled material, temperature distribution in the thickness direction of the rolled material, differences in surface roughness between the upper and lower rolls, and differences in lubrication between the upper and lower surfaces. This tendency is particularly noticeable for thick materials. FIG. 3 is an explanatory diagram of the prior art. The slab 2 is rolled by the rolling rolls 1, but the surface after rolling is curved upward. FIG. 4 is an explanatory diagram showing the development progress of surface flaws according to the prior art. Fourth
In FIG. 4(a), the material to be rolled is a slab 2, whose corners are indicated by A and B. In FIG. 4(b), the material to be rolled (
The par>8 curves downward, and the corners A and B also move to the lower surface of the bar 8. After a product is made by rolling several times in this way, the corners A and B completely move to the bottom surface of the product, as shown in Figure 4(c), and the metal flow near A and B'B. This causes curl-in scratches. FIG. 4(d) is a plan view of the product showing the occurrence of sludge defects, and since these portions are removed by shearing, the product yield is reduced. As a countermeasure, ■A guide is installed at the rear of the rolling mill to prevent sheet warping.

- During multiple rolling cycles, shear away the edges of the plate where sludge defects occur, or cut off the corners of the end face of the slab to avoid curling defects.

■Roll drive control method (twin drive method)
to change the top and bottom circumferential speeds or change the top and bottom lubrication conditions.

Measures such as these are being taken.

[Problems to be Solved by the Invention] However, the prior art has the following problems. That is, (1) The strength of the guide is limited, and it is difficult to install a strong guide due to the configuration of the rolling line.

■ Shearing off the edge of the plate or cutting off the corners of the end face of the slab during rolling will reduce the yield.

■ Even with the twin drive method, the rolling conditions for the upper and lower sides of the plate change unsteadily, so it is difficult to follow these changes and control the circumferential speeds of the upper and lower rolls.

It is an object of the present invention to solve the above-mentioned problems and to propose a method for rolling a metal sheet that avoids sheet warping.

[Means for Solving the Problems] A method for rolling a metal plate according to the present invention is such that the conveyance path of the material to be rolled at the front of the rolling mill can be tilted with respect to a horizontal plane, and the material to be rolled is moved along the rolls of the rolling mill. This is a method of rolling a metal plate that allows the angle of entry into the gap to be varied.

[Function] The metal plate rolling method of the present invention makes it possible to tilt the conveyance path of the rolled material at the front of the rolling mill with respect to the horizontal plane, and to vary the angle at which the rolled material enters the roll gap of the rolling mill. By doing so, the metal plate is always rolled horizontally. FIG. 1 is an explanatory diagram showing the principle of this rolling method. When rolling the slab 2 with upper and lower rolls 1 of equal diameter, as shown in Fig. 1(a)
As shown in , the approach angle α at which the slab enters the roll gap is
If is positive with respect to the horizontal plane, the angle β that the rolled bar makes with the horizontal plane will be positive. Also, as shown in Figure 1(b),
If the approach angle α at which the slab enters the roll gap is negative with respect to the horizontal plane, the angle β that the rolled bar makes with the horizontal plane will be negative. Therefore, by controlling the approach angle, it is possible to avoid board warpage.

[Example] FIG. 2 is an explanatory diagram showing an example of the present invention. The slab 2 is conveyed by a tiltable conveyance path (tilting beamle) 3 and rolled by a rolling roll 1.The angle of approach of the tilting beamle can be changed by a cylinder 4.5. Warp is sensor 6
The signal is sent to the computing unit 7, and the computing unit adjusts the cylinder 4.5 based on the detected information to change the approach angle. The calculator 7 has a learning function, and comprehensively judges changes in the temperature distribution in the thickness direction of the slab, which changes due to information on the warpage of the front bar, changes in the surface conditions of the upper and lower rolling rolls, changes in the heating furnace, etc. , change the approach angle 0 By adopting the present invention, board warping, which conventionally occurred 100 times a month, was reduced to 10 times. In this embodiment, a cylinder is used as the tilting mechanism of the transfer furnace, but it may be electrically driven.

[Effects of the Invention] As described above, according to the present invention, it is possible to reduce plate warpage during rolling of a metal plate, and the product yield is significantly improved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the principle of the present rolling method, Fig. 2 is an explanatory diagram showing an embodiment of the present invention, Fig. 3 is an explanatory diagram in the conventional technique, and Fig. 4 is an explanatory diagram showing the occurrence of surface defects in the conventional technique. It is an explanatory view showing progress. DESCRIPTION OF SYMBOLS 1... Rolling roll, 2... Slab, 3... Tilting cheeple, 4.5... Cylinder 6... Sensor 7... Arithmetic unit, 8... Bar

Claims (1)

[Claims] The method for rolling a metal plate is characterized in that the conveyance path for the rolled material at the front of the rolling mill is tiltable with respect to a horizontal plane, and the angle at which the rolled material enters the roll gap of the rolling mill is made variable. Method of rolling metal sheets.