JPH03401A - Rolling method - Google Patents

Abstract

PURPOSE:To stably control the sectional profile in a sheet rolling by determining an amount lapping a sheet width end part over a tapered part with a lateral flow coefficient in a rolling mill shifting working rolls having a tapered part each inversely. CONSTITUTION:The working rolls having a straight tapered part on one end of each long barrel are arranged in point symmetry and the working rolls are shifted inversely. In this case, the distribution of the lateral flow coefficients of a rolled sheet is required in advance and in this way the amount lapping the sheet width end part over the tapered part is limited to prevent the shear of the sheet and the sheet rupture by extreme middle waviness. The lateral flow coefficient is obtained by measuring the distribution of sheet thicknesses in the sheet width direction before and after the rolling and the distribution of the lengthwise elongation coefficient differences in the sheet width direction. Consequently, it is possible to control the sectional profile of the sheet without rupture and improve the yield.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a rolling method, and particularly to a rolling method that performs work roll shifting.

[Prior art] A method of controlling the plate cross-sectional profile in thin plate rolling in which work rolls having a linear tapered portion at one end of the body length are arranged symmetrically in the upper and lower points and shifted in the opposite direction (so-called work roll shift method) is This makes it possible to control profile M, which has been difficult in the past. An example of a prior art document in this field is Japanese Patent Publication No. 60-51921, which describes how the amount by which the tapered portion overlaps the edge of the sheet width (the so-called overlap amount) is determined by adjusting the amount by which the work roll is adjusted according to the width of the sheet. It is determined by performing a shift.

However, there is no mention of the amount of overlap and the angle of the tapered part in work roll shift rolling.
Further, in Japanese Patent Application Laid-Open No. 62-259606, a method is proposed in which the amount of overlap is changed depending on the plate thickness, and it is stated in the text that the front stand is more effective for the profile M84 of the amount of overlap.

[Problems to be Solved by the Invention] However, there are certain restrictions on the amount of overlap and the angle of the taper part in work roll shift rolling for stable operation and profile control. If the angle of the plate is increased, an excessive increase in plate thickness will occur at the edge of the plate width, resulting in operational problems such as plate breakage due to localized excessive tension, narrowing due to poor shape, and cracking at the edge of the plate width. will occur. In addition, selecting too small an overlap amount and a tapered part angle reduces the effect of profile control in work roll shift rolling, and the above-mentioned prior document includes these problems. The purpose of this paper is to propose a method for controlling the plate cross-sectional profile in thin plate rolling, which solves the above problems and performs stable profile control in work roll shift rolling.

[Means for Solving the Problems] The rolling method according to the present invention uses a rolling mill in which work rolls having a linear tapered portion at one end of the body length are arranged point-symmetrically and the work rolls are shifted in the opposite direction. , is a rolling method in which the amount of overlap between the tapered portion and the sheet width end portion is determined using a cross flow coefficient.

[Operation] In rolling, three-dimensional plastic flow must occur in the rolled plate in order to improve the plate thickness profile. The area where this three-dimensional plastic flow occurs depends on the deformation resistance of the plate and the distance from the width edge of the plate. In order to quantify this, the lateral flow coefficient α was defined using the following equation.

/ε=αf 1 , (H,/h,)-1, (H/h )
However, Δε: difference in elongation rate in the longitudinal direction, α: lateral flow coefficient, H,: average plate thickness on the stand entry side, hl, average plate thickness on the stand exit side, H: plate thickness at a certain plate width position on the stand entry side , h; board thickness at a certain board width position on the exit side of the stand.

The cross flow coefficient α is the ratio of the elongation difference in the longitudinal direction and the plate thickness deviation that occurs during rolling. Therefore, the closer α is to 1, the harder it is for plastic flow to occur in the sheet width direction, making it difficult to control the sheet thickness profile, and conversely, the closer α is to 0, the more likely it is for plastic flow to occur in the sheet width direction, making it difficult to control the sheet thickness profile. Show that it is easy. α depends on the distance from the sheet width edge and the deformation resistance of the rolled sheet.

The closer α is to the edge of the sheet width, the lower the deformation resistance is, the closer α approaches 0, and the easier the sheet width profile control becomes.

This is because the constraint in the width direction of the material is less as it gets closer to the edge of the strip.For this reason, it is necessary to determine the distribution of α of the rolled strip in advance and limit the amount of overlap between the tapered part of the roll and the edge of the strip. This makes it possible to prevent plate shearing and plate breakage due to extreme medium elongation. α is determined from the neck hole by measuring the distribution in the width direction of the sheet thickness before and after rolling and the distribution in the width direction of the difference in elongation in the longitudinal direction.

FIG. 1 is a graph showing the value of the cross flow coefficient α. The horizontal axis shows the deformation resistance (kg/-), the vertical axis shows the distance from the board width edge (dragon), and α is expressed as a parameter.1 As shown in the figure, the closer α is to the board width edge, the more the deformation increases. The lower the resistance, the closer it will be to O.

[Example] Table 1 shows an example of the present invention and a comparative example thereof.

Table 1 In Table 1, a cold rolling test was conducted to investigate the relationship between the cross flow coefficient and fracture. The rolling conditions were single-stand rolling, original plate thickness 3.0 ■ I, product thickness 2.1 s + s (reduction ratio 30%), plate width 1000 am, rolling load 0° 8
ton/as, front tension 15kg/wl, deformation resistance 25kg/-1 and 40kg/m, overlap of the tapered part with the edge of the plate width is 25 to 150 yen, and the taper angle of the work roll is 0.002 rad. . Comparative example 5.6.
Rolling is performed without breakage except for 10.11.12, and the cross flow coefficient in that case is 0.8 or less. The greater the deformation resistance, the smaller the amount of overlap between the tapered portion and the plate width end, even if the cross flow coefficient is the same. Note that the present invention is also applicable to hot rolling of plates.

[Effects of the Invention] As described above, according to the present invention, the cross-sectional shape of the plate is controlled without breaking by using the cross-flow coefficient during rolling of the plate.
This has the effect of improving yield.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the value of the cross flow coefficient α.

Claims (1)

[Claims] In a rolling method, in a rolling mill in which work rolls having a linear taper part at one end of the body length are arranged point symmetrically and the work rolls are shifted in the opposite direction, the amount of overlap between the tapered part and the width end of the plate is determined using a cross flow coefficient.