JP4677811B2 - Rolling method for differential thickness steel plate - Google Patents

Description

  The present invention relates to a method for rolling a differential thickness steel plate in which the plate thickness changes in a tapered shape in the longitudinal direction of the steel plate.

A differential thickness steel plate whose thickness changes in a taper shape in the longitudinal direction of the steel plate is generally manufactured by repeatedly performing forward pass and reverse pass rolling using a reversible thick plate rolling mill.
In the thick plate rolling machine, rolling can be performed while changing the roll reduction position so that the plate thickness becomes a predetermined plate thickness over the entire length in the longitudinal direction of the steel plate. The rolling speed is set. That is, there are three types, namely, a biting rolling speed when biting one end of the steel sheet, a steady part rolling speed when rolling the middle part in the longitudinal direction of the steel sheet, and a biting rolling speed when the other end of the steel sheet comes out. Rolling speed.

Therefore, when the production of the differential thickness steel plate is performed by a thick plate rolling machine, a plate thickness changing unit that changes the roll reduction position so that the plate thickness changes in a taper shape within a predetermined length range due to the restrictions. The rolling speed at the longitudinal position of the steel sheet must be set in accordance with the rolling speed.
By the way, in recent years, it has been desired to effectively improve the rolling efficiency by effectively utilizing the capacity of a reversible thick plate rolling mill.

Here, a rolling method will be described in which a thick plate rolling machine is used to provide a step in which the plate thickness changes in a taper shape within a predetermined length range at at least one location in the longitudinal direction of the steel plate. The differential thickness steel sheet is generally made of slab, etc., and after rolling the slab into a reversible thick plate rolling machine, it is rolled once until the plate thickness reaches the desired thickness over the entire length, then one end When the steel sheet is re-engaged and rolled to a predetermined position, the rolling mill is stopped and the reverse rotation is immediately performed, and biting-back rolling with a step in the longitudinal direction is performed so as to obtain a thin target thickness. At that time, in the rolling method of the differential thickness steel sheet of Patent Document 1, the roll reduction position is changed so that the rolling load in the forward pass and the reverse pass of the bite rolling with a step in the longitudinal direction becomes equal.
JP 7-265924 A

  Conventionally, when rolling is performed by changing the roll reduction position at at least one intermediate portion in the longitudinal direction of a steel plate using a thick plate rolling mill, the rolling speed in the range of the thickness change portion is set to a predetermined low rolling The speed VL (= VH × α: α = 0.8 to 0.9, VH is the rolling speed at the constant thickness portion of the material to be rolled), and the biting rolling speed and the biting rolling speed are low rolling. Since the speed was set to be the same as the speed VL, there was a problem that the capacity of the plate rolling mill could not be effectively utilized. The reason why the rolling speed in the range of the thickness change portion is set to the predetermined low rolling speed VL will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1 (a) is a schematic diagram showing a cross-sectional shape of a material to be rolled, which is a material suitable for the differential thickness steel plate to which the present invention is applied, and FIG. 1 (b) is obtained by rolling it. It is a schematic diagram which shows the cross-sectional shape of the 1 step taper steel plate. 1 indicates the longitudinal direction of the steel sheet, a indicates one end of the steel sheet, and b indicates the other end of the steel sheet.

  In the range K2 (hereinafter referred to as a stepped portion) of the thickness change portion of the material to be rolled, which is the material of the differential thickness steel plate, the step in the plate thickness is large as shown in FIG. For this reason, when rolling the material to be rolled by setting and changing the roll reduction position in at least one middle portion in the longitudinal direction of the steel sheet, the rolling speed is reduced to match the roll reduction device when rolling the stepped portion. It is necessary to change the setting of the roll reduction position, otherwise the predetermined reduction cannot be applied to the stepped portion of the material to be rolled, and the position accuracy of the thickness change portion of the difference thickness steel plate and the difference thickness steel plate This is because the inclination accuracy of the plate thickness changing portion cannot be ensured.

  Therefore, even when the material to be rolled as shown in FIG. 1A is rolled to obtain a one-step tapered steel plate as shown in FIG. It is desired to improve the rolling efficiency while maintaining the positional accuracy and the inclination accuracy of the plate thickness changing portion L2 of the differential thickness steel plate. In FIG.1 (b), L1 shows the range of the plate | board thickness constant part of the one where the plate | board thickness of a difference thickness steel plate is thick, L3 shows the range of the plate | board thickness constant part of the one where the plate | board thickness of a difference thickness steel plate is thin. H1 indicates the plate thickness in the range L1 of the plate thickness constant portion where the thickness of the differential thickness steel plate is thicker, and H2 indicates the plate thickness in the range L3 of the plate thickness constant portion where the thickness of the differential thickness steel plate is thin. .

However, in the rolling method of the differential thickness steel plate of Patent Document 1, the thickness accuracy and the steel plate shape aimed at the thin portion are improved, but the positional accuracy of the thickness change portion of the differential thickness steel plate and the thickness change of the differential thickness steel plate. No mention is made of a rolling method for improving the rolling efficiency while maintaining the inclination accuracy of the part.
The present invention eliminates the above-mentioned problems of the prior art, and maintains the positional accuracy of the thickness change portion of the differential thickness steel plate and the inclination accuracy of the thickness change portion of the differential thickness steel plate while achieving an improvement in rolling efficiency. It aims at providing the rolling method of a steel plate.

The inventors of the present invention diligently studied the rolling method of the differential thickness steel sheet, and obtained the knowledge that the above-mentioned problems can be solved by effectively setting the rolling speed over the entire length in the longitudinal direction of the steel sheet. It came to.
The present invention is as follows.
When rolling the material to be rolled so that the plate thickness becomes a predetermined plate thickness over the entire length in the longitudinal direction of the steel plate, the plate thickness is tapered within a predetermined length at at least one location in the longitudinal middle portion of the steel plate. A rolling method of a differential thickness steel plate that rolls a material to be rolled by changing the roll reduction position so as to change, wherein the setting of the rolling speed over the entire length in the longitudinal direction of the steel plate is a constant thickness range of the differential thickness steel plate performed divided into a plate thickness change range, the setting of the rolling speed in the plate thickness a range of the difference thick steel plate, the longitudinal position of the steel sheet on the horizontal axis and the rolling speed on the vertical axis, biting of the steel sheet An inclined line for accelerating a low rolling speed corresponding to a rolling speed or a biting rolling speed, a constant line for maintaining the accelerated high rolling speed over a certain range, and reducing the high rolling speed to the low rolling speed. Refraction on multiple polygonal lines that represent a sloping line It performs using the value, the setting of the rolling speed in the thickness range of change in the difference thick steel sheet, with the high value of lower than the rolling speed the low rolling speed in the plate thickness a range of the difference steel plate And then rolling the material to be rolled. Further, the rolling method of the differential thickness steel sheet, wherein the biting rolling speed and the biting rolling speed are set higher than the low rolling speed which is a rolling speed in a thickness change range of the differential thickness steel sheet. It is.

According to the rolling method of the differential thickness steel sheet according to the present invention, the thickness of the steel sheet is set to a value at the refraction point of a plurality of broken lines expressed by taking the longitudinal position of the steel sheet on the horizontal axis and the rolling speed on the vertical axis. Since the range of the change part and the rolling speed in the vicinity of the longitudinal direction can be set to a predetermined low rolling speed, the position accuracy of the thickness change part of the differential thickness steel sheet and the inclination accuracy of the thickness change part of the difference thickness steel sheet are set. Can keep.
Further, according to the rolling method of the differential thickness steel sheet according to the present invention, the thickness of the steel sheet is set to a value at the refraction point of a plurality of broken lines expressed by taking the longitudinal position of the steel sheet on the horizontal axis and the rolling speed on the vertical axis. A part of the rolling speed in the range of the plate thickness constant part where the plate thickness is thick following the one side of the changed part, and the part of the rolling speed in the plate constant part of thin plate thickness following the other side of the plate thickness changed part Since it can be set to a high rolling speed that is faster than the low rolling speed except for, the material to be rolled has been rolled at a predetermined low rolling speed over the entire length in the longitudinal direction of the steel sheet as in the past. Compared to the case, the rolling time can be shortened and the rolling efficiency can be improved.

  Further, according to the rolling method of the differential thickness steel sheet according to the present invention, the biting rolling speed when biting one end portion of the steel plate and / or the biting rolling speed when biting the other end portion of the steel plate are reduced to a predetermined low level. It is also possible to set a value faster than the rolling speed, and as a result, the penetration speed of the steel sheet into the rolling mill can be made faster than before, and it is possible to further reduce the rolling time.

Hereinafter, an embodiment will be described with reference to FIG. FIG. 2 is a characteristic diagram showing a combined rolling speed pattern obtained by applying the rolling method of the present invention to the one-step tapered steel plate shown in FIG. 1 in comparison with a conventional rolling speed pattern.
In FIG. 2, VIN indicates the biting rolling speed when biting the one end a of the steel plate, and VOUT indicates the biting rolling rate when biting the other end b of the steel plate. VH indicates a high rolling speed higher than a predetermined low rolling speed VL. The predetermined low rolling speed VL is determined by the position accuracy of the plate thickness changing portion of the differential thickness steel plate, the inclination accuracy of the plate thickness changing portion of the differential thickness steel plate, and the specifications such as a reduction device. Further, in FIG. 2, L1, L2, and L3 respectively indicate the ranges of the longitudinal direction portion of the differential thickness steel plate shown in FIG.

  That is, in the rolling method of the differential thickness steel sheet according to the present invention, the roll reduction position is set and changed so that the sheet thickness changes in a taper shape within a predetermined length range at at least one place in the longitudinal middle portion of the steel sheet. Rolling method for rolling a material to be rolled, in which the setting of the rolling speed over the entire length in the longitudinal direction of the steel sheet is set as shown in FIG. After carrying out using the values at the refraction points P1 to P10 of a plurality of broken lines expressed by taking the speed, the material to be rolled is finish-rolled.

  In that case, according to the rolling method of the differential thickness steel sheet according to the present invention, the range L2 of the sheet thickness changing portion for changing the setting of the roll reduction position and the rolling speed in the vicinity of the longitudinal direction are set to a predetermined low rolling speed VL. Therefore, the positional accuracy of the plate thickness changing portion of the differential thickness steel plate and the inclination accuracy of the plate thickness changing portion of the differential thickness steel plate can be maintained. Further, according to the rolling method of the differential thickness steel sheet according to the present invention, the thickness change portion is set to a value at the refraction point of a plurality of broken lines expressed by taking the longitudinal position of the steel sheet on the horizontal axis and the rolling speed on the vertical axis. The rolling speed in the range L1 of the plate thickness constant part where the plate thickness of the difference thickness steel plate is larger, and the rolling speed in the range L3 of the plate thickness constant portion where the plate thickness of the difference thickness steel plate is thin, following one side Is set to a high rolling speed VH, which is faster than the low rolling speed VL except for a part, and the value is constant, and then the material to be rolled is rolled. Compared with the case where the material to be rolled is rolled at a predetermined low rolling speed VL having a constant value, the rolling time can be shortened and the rolling efficiency can be improved.

  Here, in FIG. 2, the rolling speed is constant between the refraction points P1 and P2, between the refraction points P3 and P4, between the refraction points P5 and P6, between the refraction points P7 and P8, and between the refraction points P9 and P10. On the other hand, acceleration / deceleration is performed between the refraction points P2 and P3, between the refraction points P4 and P5, between the refraction points P6 and P7, and between the refraction points P8 and P9, and the rolling speed changes linearly. In FIG. 2, the steel plate position after rolling is shown as the longitudinal position of the steel plate on the horizontal axis, but the steel plate position of the material to be rolled, which is a material of the differential thickness steel plate, may be taken. In FIG. 2, P1 and P10 are speed setting points outside the steel plate, but are essential for setting the speed of the thick plate rolling mill, and therefore included in the setting of the rolling speed over the entire length in the longitudinal direction of the steel plate. That is, the rolling speed before biting the one end a of the steel sheet represents the penetration speed of the steel sheet into the rolling mill, and the rolling speed after biting through the other end b of the steel sheet is equal to that of the steel plate from the rolling mill. Indicates separation speed.

  In the rolling method of the differential thickness steel sheet according to the present invention, the setting of the rolling speed over the entire length in the longitudinal direction of the steel sheet is represented by the refractive point P1 of a plurality of broken lines expressed by taking the longitudinal direction position of the steel sheet on the horizontal axis and the rolling speed on the vertical axis. Since the value of ~ P10 is used, the biting rolling speed VIN when biting the one end a of the steel sheet and / or the biting rolling speed VOUT when biting the other end b of the steel sheet are set to a predetermined low value. It is possible to set a value faster than the rolling speed VL. As a result, it is possible to increase the penetration speed of the steel sheet into the rolling mill more than before, thereby further reducing the rolling time.

  In the above description, the difference thickness steel sheet for rolling the material to be rolled by changing the roll reduction position so that the sheet thickness changes in a taper shape within a predetermined length range at one location in the longitudinal direction of the steel sheet. Although the rolling method was demonstrated, this invention can be applied suitably also to the rolling method of a difference thickness steel plate as shown in FIG. 3 (a) to 3 (c) show a differential thickness steel plate that rolls the material to be rolled by changing the roll reduction position so that the thickness changes in a taper shape at two locations in the middle in the longitudinal direction of the steel plate. Indicated.

  Fig.3 (a) is a schematic diagram which shows the cross-sectional shape of a two-step taper steel plate, FIG.3 (b) is a schematic diagram which shows the cross-sectional shape of a convex taper steel plate. Moreover, FIG.3 (c) is a schematic diagram which shows the cross-sectional shape of a concave taper steel plate. In FIG. 3A, H3 indicates the plate thickness in the range L4 of the plate thickness constant portion having an intermediate thickness.

The rolling method of the differential thickness steel sheet according to the present invention was applied to the two-stage tapered steel sheet shown in FIG.
Here, the dimensions of the manufactured differential thickness steel plate are as follows.
Thickness H1 = 20 mm in the range L1 of the thick constant thickness portion,
Thickness H2 = 12 mm in the range L3 where the thickness is constant.
Thickness H3 = 16 mm in the range L4 of the constant thickness portion of the middle thickness,
Range L1 = 2000 mm where the thickness is a constant thickness portion,
The length L2 = 1000 mm of the plate thickness changing portion of the thicker plate thickness,
The length L2 = 1000 mm of the plate thickness changing portion of the thinner plate thickness,
Range L3 = 2000 mm where the thickness is a constant thickness portion,
Range L4 = 2000 mm where the thickness is an intermediate plate thickness constant part,
Sheet width of the differential thickness steel plate = 3200 mm.

In addition, as shown in FIG. 4, including the penetration speed and separation speed of the steel sheet into the thick plate rolling mill, the setting of the rolling speed over the entire length in the longitudinal direction of the steel sheet is performed using the values at the 14 refraction points of the broken line. After being performed, the material to be rolled was rolled. Values at 14 refraction points are as follows.
P1 rolling speed = P2 rolling speed = VIN = VL = 75 to 90 m / min,
P3 rolling speed = P4 rolling speed = VH = VL + 75 m / min,
P5 rolling speed = P6 rolling speed = VL = 75 to 90 m / min,
P7 rolling speed = P8 rolling speed = VH = VL + 75 m / min,
P9 rolling speed = P10 rolling speed = VL = 75 to 90 m / min,
P11 rolling speed = P12 rolling speed = VH = VL + 75 m / min,
P13 rolling speed = P14 rolling speed = VOUT = VL = 75 to 90 m / min.

However, the thick plate mill used for finish rolling was a four-stage reversible rolling mill, and the number of passes of finish rolling was four.
By applying the present invention to the above-described rolling of the differential thickness steel plate, the position accuracy of the thickness change portion of the differential thickness steel plate and the inclination accuracy of the thickness change portion of the differential thickness steel plate are maintained, and before applying the present invention. Compared with this, the rolling time could be shortened and the rolling efficiency could be improved.

(A) is a schematic diagram which shows the cross-sectional shape of the to-be-rolled material which is a raw material of a suitable thickness difference steel plate to which this invention is applied, (b) is the 1 step | paragraph taper steel plate obtained by rolling it. It is a schematic diagram which shows a cross-sectional shape. It is a characteristic view which shows the rolling method of this invention compared with the pattern of the conventional rolling speed. It is a schematic diagram which shows the cross-sectional shape of another suitable thickness difference steel plate which applies the rolling method of this invention. It is a characteristic view which shows the rolling speed pattern at the time of applying this invention to the differential thickness steel plate shown to Fig.3 (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Longitudinal direction of steel plate a One end part of steel plate b Other end part of steel plate K1, K2, K3 Range of longitudinal part of rolled material which is material of differential thickness steel sheet L1, L2, L3 Longitudinal part of differential thickness steel sheet Range H1 Thickness constant plate thickness range L1 thickness H2 Thin thickness constant thickness range L3 thickness H3 Thickness intermediate thickness constant range L4 thickness VIN Biting rolling speed VH High rolling speed VL Low rolling speed VOUT Biting rolling speed

Claims (2)

When rolling the material to be rolled so that the plate thickness becomes a predetermined plate thickness over the entire length in the longitudinal direction of the steel plate, the plate thickness is tapered within a predetermined length at at least one location in the longitudinal middle portion of the steel plate. It is a rolling method of a differential thickness steel plate that rolls a material to be rolled by changing the roll reduction position so as to change,
The setting of the rolling speed over the entire length in the longitudinal direction of the steel sheet is performed by dividing the difference thickness steel sheet into a sheet thickness constant range and a sheet thickness change range. Taking the longitudinal position of the steel sheet as the axis and the rolling speed as the vertical axis, the inclined line for accelerating the low rolling speed corresponding to the biting rolling speed or the biting rolling speed of the steel sheet, and the accelerated high rolling speed. The difference thickness steel plate is formed using a refraction point value on a plurality of broken lines representing a constant line maintained over a certain range and an inclined line decelerating the high rolling speed to the low rolling speed. The setting of the rolling speed in the thickness change range is performed using the value of the low rolling speed slower than the high rolling speed in the plate thickness constant range of the differential thickness steel sheet, and then the material to be rolled is rolled. A rolling method of the differential thickness steel sheet. The said biting rolling speed and the said biting rolling speed are set to a value faster than the said low rolling speed which is a rolling speed in the plate | board thickness change range of the said difference thickness steel plate. Rolling method of different thickness steel plate.

Images