JPS62179804A - Cold rolling method for steel sheet including control means for amount of edge drop - Google Patents

Abstract

PURPOSE:To control the thickness in the transverse direction of a steel sheet within a target range and to improve yield by controlling a setup model and preset model by using an equation of evaluating the deviation of the thickness in the transverse direction of the sheet. CONSTITUTION:The rolling load and bender pressure of the 1st stand are calculated by using the conditions of a rolling material, pass schedule, roll conditions and the target value of the deviation of the thickness in the transverse direction of the steel sheet in the stage of making cold rolling. The shift positions of work rolls are set by equation II in accordance with the setup model and the rolling is started. The shift positions of the work rolls and the roll bender pressure are corrected at least once by equation III of the preset model by using the actually measured value of the rolling load in the midway of rolling and the thickness in the transverse direction is controlled within the target range by evaluation equation I.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for cold rolling a steel plate including means for controlling the amount of edge drop. The present invention relates to a method for cold rolling a steel sheet, including means for controlling the amount of edge drop, which improves thickness deviation in the width direction of a rolled material caused by axial center deflection and roll flattening.

(Prior Art) Conventionally, a method for performing work roll bending and work roll shifting in order to improve the thickness deviation in the width direction of a steel plate is disclosed in Japanese Patent Laid-Open No. 59-133903 and Japanese Patent Laid-Open No. According to No. 60-12213 and the like, two control variables for controlling the sheet thickness deviation in the sheet width direction are a shift pattern by shifting a work roll and a bender pressure due to roll bending.

Also, according to Japanese Patent Application Laid-open No. 12213/1983,
Similar to the method described in No. 9-133903, the work roll shift amount and roll bending amount are controlled,
In other words, the measured value of the edge drop of the steel plate from the plate thickness gauge at the exit side of the final stand is compared with the target edge drop value of the steel plate, and based on this comparative calculation value, the shift control of the trapezoidal work roll in the width direction of the plate is performed. Then, the operating pressure control of the roll bender is performed.

(Problems to be solved by the invention) However, although the above two methods are particularly effective in countering edge drops, in the invention described in JP-A-59-133903, the thickness deviation in the width direction is There is a problem in that the control effect is inferior by controlling only the amount of shift and the bender pressure, which are greatly affected by the roll rolling load, and the invention described in JP-A-60-12213 also has a problem in that the control amount is variable. Ta.

In other words, depending on the conventional method, after cold rolling, it is difficult to avoid the tendency for the thickness of the material to be rolled to become suddenly thinner near the end of the material. In this way, when there is a thickness deviation in the direction of plate 1 in a cold-rolled steel plate, it not only reduces the yield due to cutting out defective parts such as edge drops, but also prevents automation of the processing process at the place where the steel plate is used. This method had the drawback of causing problems such as the following.

(Means for Solving the Problems) The present invention provides edge drop in cold rolling that can eliminate and improve the melting point or drawbacks of conventional edge drop control means during cold rolling of rolled steel sheets. For the purpose of providing a cold rolling method comprising control means,
This object can be achieved by providing the method according to the claims.

That is, the present invention provides a steel plate including means for controlling the amount of edge drop by a cold tandem rolling mill in which a rolling mill capable of shifting trapezoidal work rolls with tapered roll ends in the widthwise direction of the roll is arranged at least in a first stand position. In the cold rolling method of Based on a predetermined setup model that determines the optimum shift amount, set the shift position of the work roll and start rolling of the material to be rolled; the work roll shift position and roll bender pressure are corrected at least once by a preset model for correcting the rolling load calculation error of the set-up model; The present invention relates to a method for cold rolling a steel sheet, including means for controlling edge drop amount.

The present inventors have developed a method for cold rolling a steel plate using a conventionally known cold tandem rolling mill having a rolling mill that can shift trapezoidal work rolls with tapered roll ends in the strip width direction. The present invention was completed based on the new finding that it is possible to make the sheet thickness uniform in the width direction by determining the optimal shift amount setting value and correction value for the trapezoidal work roll using the above and other setting values. It is.

The present inventors investigated the phase relationship between the roll rolling load of the first stand and the thickness deviation in the width direction of the product steel sheet, and found that there was a strong phase ISl relationship.

In addition, multiple regression analysis was performed using the rolling load of the first stand, the roll bender pressure of the first stand, the taper amount and shift amount of the trapezoidal whirl roll, and it was found that the thickness deviation in the width direction was Results were obtained that could be fully evaluated.

Based on the above findings, the present inventors came up with a model for controlling plate thickness deviation in the plate width direction based on the following evaluation formula.

Next, the present invention will be explained in detail.

The present invention relates to a steel plate cold rolling method characterized by two control means: control using a set-up model and processing control using a preset model, which will be described below. This was done using an evaluation formula.

CI) Plate width direction plate thickness deviation evaluation formula % formula % (1) P: 1st stand rolling load (hereinafter simply referred to as 1st stand load) F3: it stand roll bender pressure (hereinafter referred to as 1st stand bender pressure ) WS3: Work roll shift amount TA: Trapezoidal roll taper amount NS: Post-stage stand parameters b, c, d, e, f: Constants The above-mentioned post-stage stand parameters...? ) The latter stage stands mentioned include all the stands after the first stand, or any one stand or multiple stands after the second stage stand that particularly affects the edge drop, and also includes NS, that is, the latter stage stands. The tension, load, etc. of the rear stage stand are used as stand parameters.

According to the present invention, the above 2
The work roll shift il wsδ is calculated by the following formula (2).

(II) Control using a setup model This control starts before rolling the material to be rolled, and sets the optimum WSδ. The data taken into this control are the conditions of the rolled material, pass schedule, and roll conditions.

After calculating the strip width, the ED target value, the rolling load of the first stand, and the bender pressure, the optimum WS δ setting value is calculated using equation (2). The calculated WSδC is a mechanical specification.

The upper and lower limits of the work roll shift amount WSδC are checked according to the operational specifications and the allowable bender pressure conditions, and after this check, the work roll shift) iiwsδ'C is preset and this control is completed. Here, the limit value of the operational specifications of WS3 is the value that can prevent edge build-up of the product, that is, high speed bot, and the allowable range of bender pressure is the value at the exit of the mill where the trapezoidal work roll is shifted in the width direction of the strip. This is a book to prevent deterioration of shape. The flow of this control is shown in FIG.

(1) Control using preset model This control is for correcting the rolling load calculation error caused by the set-up model during rolling of the material to be rolled, and is executed 41 times per coil. The difference ΔP between the actual rolling load value GPa) and the calculated value (Pc) is calculated, and the formula (
Approximate formula (3) of 2), awsδ−−b−UP−1,−
0, -1-(3) to find ΔwsJ and change the settings of WS3. In this control, when calculating ΔWSδ, the upper and lower limits of WS3 are checked based on the bender pressure allowable range, similar to the control based on the setup model shown in the small diagram. The flow of this control is shown in Figure 2. Furthermore, the linkage of this control with the host computer is shown in FIG.

Note that this control needs to be performed at least once when WS3 is set in the setup model and rolling is started, and when the rolling wax becomes almost stable (2), for example, when the steady rolling speed is reached.

Next, the present invention will be explained with reference to examples.

Example 5 continuous cold pressure f, rolling load of the first stand of the machine.

Cold rolling was performed by controlling the parameters of the bender pressure by the control means of the present invention, and a product having a handling thickness Q of 5 m and a plate width of 890 mm was manufactured from a low carbon steel mother plate with a thickness of 2.3 fi. The pass schedule was as shown in the table below.

However, in the table above, the unit tension in the hot rolled sheet column is 3.7 kg/
/II! ! 2 is the unit tension on the 1st stand person side, and the unit tension of the 1st, 2nd, 3.4th and 5th stands is on the exit side of each stand.

Setting the rolling load and bender pressure by the control means of the present invention,
After correcting the rolling load error, the shift) fi W8δ= −
40, the edge drop amount obtained by changing the load EC973TON → 946 TON and the pressure 35TON → 32 TON (500 and 1O from the plate edge)
The plate thickness difference at the location with Iu+) was 8 μm.

In this example, the tension and rolling load of the second and third stage stands were used as the parameters of the NSI rear stage stand in formula α).

Comparative example: From the above mother plate to a product with the same thickness and width (conventional shift)
It was manufactured by setting the lid wsJ -M=-20. Thus: The edge drop amount of the promoted product steel sheet was 15 μm.

As described above, according to the cold rolling method using the conventional control means,
The edge drop amount, that is, the thickness deviation in the width direction, which is the difference in thickness between 50 mm and 10 mm from the edge of the sheet, is on average 15 ~
20 PM, and the point where the plate thickness suddenly becomes thinner near the plate edge is about 25 mm from the plate edge, but according to the cold rolling method using the control means of the present invention, the plate thickness in the width direction The thickness deviation is 10 μm or less, and the position where the plate thickness rapidly decreases near the edge of the plate moves closer to the edge of the plate, resulting in a substantially rectangular cross-sectional shape in the width direction of the plate.

(Effects of the Invention) As described above, according to the present invention, the deviation of the target plate thickness at the edge of the plate is reduced and the yield is improved, and the industry that uses the rolled material manufactured by the present invention can use the conventional rolled material. Since the hindrance to automation caused by this is eliminated, further automation becomes possible.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the flow of control using the set-up model of the present invention, Fig. 2 is a diagram showing the flow of control using the preset model of the present invention, and Fig. 3 is a diagram showing the linkage of control using the preset model with a host computer. FIG. l... Upper work roll, 2... Lower work roll, 3
...Bender, 4...Cylinder.

Claims (1)

[Scope of Claims] 1. Edge drop amount control means using a cold tandem rolling mill in which a rolling mill capable of shifting trapezoidal work rolls with tapered roll ends in the strip width direction is arranged at least at a first stand position. In a method for cold rolling a steel plate including: Roll rolling load and roll bender pressure in the first stand calculated using rolled material conditions, pass schedule, roll conditions, and target thickness deviation in the width direction of the trapezoidal workpiece. Based on a predetermined setup model that determines the optimal shift amount of the rolls, set the shift position of the work rolls and start rolling the material to be rolled; correct the work roll shift position and roll bender pressure at least once using a preset model for correcting the rolling load calculation error of the setup model; and adjust the thickness of the steel plate in the width direction to a predetermined target range. 1. A method for cold rolling a steel plate, comprising means for controlling an edge drop amount.