JPH0459111A - Method for controlling crown on cold rolling of tandem mill - Google Patents

Abstract

PURPOSE:To improve the working efficiency by specifying the taper effect quantity of each stand of the tandem mill and setting the position of the work roll shift. CONSTITUTION:The taper effect quantity ( h) displaying that the metallic strip to be cold rolled on the tandem mill is in the good state is calculated with the equation. Here, (ah+b) is the constant decided with the roll dimension of each stand, WRT is the value decided with the taper angle (theta) of the work roll, WRdelta is the shift position of the work roll. In order to make this taper effect quantity to be <=1% of each outlet side sheet thickness (h), the work roll shift position is moved to its axial direction and set. Therefore, on the case of the sheet width change and the outlet side sheet thickness change, etc., the taper effect quantity can be easily set and the working efficiency can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a rolling stand in which two or more rolling stands equipped with tapered work rolls at one end of the body are upstream of a final stage rolling stand. When cold-rolling a metal strip using a tandem mill installed on the side, it is possible to uniformly control the thickness distribution of the rolled metal strip in the width direction of the strip, and also to be able to grasp this control amount, making it possible to control the thickness distribution in the width direction of the rolled metal strip. The present invention relates to a crown control method in cold rolling using a tandem mill, which enables rolling into a good shape with high accuracy in thickness.

[Conventional technology]

In general, metal strips such as hot-rolled steel strips, which are raw sheets for cold rolling, have a thickness distribution in which the thickness decreases from the center in the width direction toward the edges, that is, a convex crown shape, especially at the edges in the width direction. The plate thickness decreases rapidly in the vicinity. This is because in the conventional cold rolling method in which a metal strip is rolled by opposing cylindrical work rolls, an external force is applied to bend the work rolls in the axial direction in order to maintain a constant thickness of the metal strip at the center of the width of the strip. Due to roll bending ↓ rolling, the work roll comes into strong contact with the metal strip, especially near the edges in the width direction, resulting in a shape in which the thickness of the strip near the edges in the width direction decreases rapidly. This is because it is rolled.

However, in cold rolling a metal strip, it is required to roll such a convex crown-shaped metal strip so that it has a good rolled shape and a uniform thickness distribution with a rectangular cross section.

Then, the tapered part is started to be tapered by two or more rolling stands arranged in tandem, each of which has a tapered part formed at one end of the opposite left and right sides of the body of the opposing work rolls. There is a rolling method in which the edge of the metal strip to be rolled is positioned between a point and an end point and cold rolling is performed, thereby suppressing the decrease in the thickness near the edge in the width direction of the metal strip and increasing the accuracy of the strip thickness. Proposed. This is because when a metal strip is cold-rolled using this rolling method, the distance between opposing work rolls at the tapered part of the work rolls increases, so the thickness of the metal strip at the tapered part decreases. This is suppressed compared to the center portion in the width direction of the band, resulting in a good plate thickness shape for the metal band as a whole.

However, in the case of 2 in which such a tapered part is formed,
When cold-rolling a metal strip by passing it through rolling stands arranged in tandem or more, the set value of the distance from the edge in the width direction of the metal strip on each rolling stand to the taper start point of the work roll is If it is not appropriate, the shape of the cold-rolled metal strip will be poor and the thickness of the metal strip as a whole will not be good. Therefore, in each rolling stand, it is necessary to set the distance from the widthwise edge of the metal strip to the taper start point of the work roll to an appropriate value, but conventionally there is no means for appropriately setting this value. Since the distance from the widthwise edge of the metal strip to the taper start point of the work roll was set based on the operator's intuition, it was difficult to determine how much the plate thickness at the widthwise edge of the cold-rolled metal strip could be improved. It can only be confirmed after rolling that the distance from the widthwise edge of the metal strip to the taper start point of the work roll is set in advance to obtain the target thickness accuracy. However, since the method is rotated, there are disadvantages in that the yield and work efficiency are lowered.

That is, when attempting to roll a metal strip to a desired thickness in one bus using a tandem mill equipped with two or more rolling stands each having a tapered work roll at one end of the body, Since the metal strip is rolled sequentially, the thickness near the edge relative to the center in the width direction varies at each rolling stand. Therefore, in order to obtain the target thickness accuracy, the taper start point of the work roll is adjusted from the edge in the width direction of the metal strip. As it becomes more difficult to set the distance accurately in advance, the above-mentioned drawbacks will become more apparent, and the shape of the metal strip passed through the final stage rolling stand will be poor, resulting in a good thickness shape as a whole of the metal strip. There was a drawback that a phenomenon in which the process did not occur occurred, resulting in a decrease in yield and a decrease in work efficiency.

[Problem to be solved by the invention]

The present invention solves the above-mentioned drawbacks of the prior art and sets the distance from the taper start point of the work roll tapered at one end of the body to the edge of the rolled metal strip in each rolling stand. can be set in advance to a setting value that can obtain the desired plate thickness accuracy, and it is also possible to grasp the plate thickness accuracy of the metal strip passed through the final stage rolling stand, thereby improving yield. It is an object of the present invention to provide a method for controlling crown in cold rolling using a tandem mill, which is excellent in improving the process efficiency and working efficiency.

[Means to solve the problem]

As a result of intensive research to solve this problem, the present inventors have found that for the reasons explained below with some speculation,
A predetermined value near the edge of the metal strip in the width direction when the rolled metal strip is cold-rolled by a cylindrical work roll and when it is cold-rolled by a work roll with a taper tapered at one end of the body. The thickness difference at the position (hereinafter referred to as the taper effect amount) is the exit side plate thickness of the rolled metal strip, and the distance from the widthwise edge of the rolled metal strip to the taper start point of the work roll (hereinafter referred to as the shift of the work roll) They completed the present invention by discovering that it is proportional to the taper angle (referred to as position) and the taper angle of the taper attached to the work roll.

■ In a rolling stand in which a tapered part is formed at one end of the right and left opposite sides of the body of each of the opposing work rolls, the edge positions in the width direction of the rolled metal strip are opposite when no load is applied. The amount of increase in the distance between the work rolls is determined by the tangent tan of the taper angle θ of the work rolls.
The value WRT obtained from θ (the amount of decrease in the diameter of the work roll per 1001 lengths of the tapered part in the roll axis direction),
That is, W RT = 100 (WRT
It can be approximated as a value of XWRδ)/100.

■ The influence of the tapered part of the work roll on the elastic deformation of the work roll during cold rolling is that the tapered part is locally formed so that it is located near the widthwise edge of the rolled metal strip. This mainly affects the roll flatness of the work roll, and has a small effect on the deflection of the roll axis. Therefore, at a predetermined position near the edge in the width direction of the rolled metal strip located at the tapered portion of the work roll, the rolling load is reduced due to an increase in the tension of the rolled metal strip, so that the amount of flattening of the work roll is reduced.

■ Work roll flattening reduction amount and rolling load reduction amount.

Since the amount of reduction in rolling load and the amount of increase in tension, and the amount of increase in tension and amount of increase in thickness on the exit side are each approximately proportional to each other, the amount of decrease in flatness of the work roll and the amount of increase in thickness on the exit side are approximately proportional to each other. Ignoring the influence of the taper section on the deflection of the work roll axis, the increase in thickness at the exit side is calculated from the increase in the gap between the opposing work rolls at the edge position in the width direction of the rolled metal strip under no load. This is obtained by subtracting the amount of decrease in the flatness of the work roll, and the amount of increase in the thickness of the exit side plate is approximately proportional to the amount of increase in the gap between the work rolls.

■ When the thickness of the rolled metal strip near the edge in the width direction increases due to the work roll being tapered, the elongation rate with respect to the center of the width of the metal strip near this edge decreases, and this elongation rate increases. The amount of decrease increases or decreases depending on the thickness of the exit side plate, and is almost proportional to the amount of increase in tension described above, and has almost no relation to other rolling conditions.

From the knowledge in the above sections ① to ②, the value a h + b is derived from the thickness of the exit side plate at the widthwise center of the rolled metal strip and the constants a and b determined by the roll dimensions of each rolling stand.
The taper effect is determined by the product of the value WRT obtained from the tangent tanθ of the taper angle θ of the work roll, and the shift position WRδ of the work roll indicating the distance from the edge of the metal strip to be rolled to the taper start point of the work roll. amount Δh,
That is, Δh = (ah + b) X W RT
They completed the present invention by discovering that it is possible to estimate X W Rδ.

Hereinafter, the method of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a side view showing an example of a tandem mill in which three rolling stands each having a tapered work roll are arranged in front of the final rolling stand for carrying out the method of the present invention; Figure 2 is an explanatory cross-sectional view taken along line A-A in Figure 1;
Fig. 3 is an enlarged explanatory view of part B in Fig. 2, and Fig. 4 is a cross-sectional view of a metal strip cold-rolled on a rolling stand equipped with tapered work rolls at a predetermined position from the edge. A diagram showing the relationship between the measured value and the value obtained from the formula for the amount of taper effect. Figure 5 shows a metal strip and a cylindrical workpiece that were cold-rolled by the method of the present invention using the tandem mill shown in Figure 1. Figure 6 shows the distribution of sheet thickness deviation with respect to the center in the width direction for metal strips cold-rolled by a tandem mill equipped with four rolling stands equipped with rolls. A diagram showing the relationship between the taper effect amount and the shift position of the work roll when a metal strip to be rolled is cold-rolled with the exit side plate thickness and the taper angle of the work roll constant on one rolling stand equipped with a work roll. , Figure 7 shows the taper effect amount and workpiece when a metal strip to be rolled is cold-rolled on one rolling stand equipped with tapered work rolls with the exit side thickness and work roll shift position constant. Figure 8 is a diagram showing the relationship between the taper angle of the roll and the tangent. It is a figure which shows the relationship between the taper effect amount and exit side plate thickness when cold rolling is carried out at a constant value.

To carry out the method of the present invention, first, as shown in FIGS. 1 to 3, a work roll 3 having a tapered portion 3a formed at one end of each body portion 3b is first prepared. A tandem mill is prepared in which at least two or more rolling stands 2, whose tapered parts 3a are located on left and right opposite sides and face each other, are disposed at least on the upstream side of the final stage rolling stand 2. The work roll 3 on which the tapered portion 3a is formed has a taper starting point T, which is the boundary point between the body portion 3b and the tapered portion 3a, which have the same diameter. It is installed so as to be freely movable in the axial direction so that the distance from to the edge in the width direction of the rolled metal 1E1, that is, the shift position WRδ of the work roll 3 can be set to a predetermined value.

A rolling stand 2 on which such work rolls 3 are installed
As shown in FIGS. 1 and 2, the rolled metal strip 1 is
In addition to the 6-high rolling mill, which has work rolls 3 on both sides of the work roll 3, an intermediate roll 4 outside the work roll 3, and a set of backup rolls 5 outside the work roll 3, a cluster mill, Various rolling stands can be used, such as a Sendzimya mill.

In addition, as the final stage rolling stand 2, a one equipped with ordinary cylindrical work rolls is used, but a rolling stand 2 equipped with tapered work rolls 3 is used. Tapered work roll 3
The metal strip l to be rolled may be rolled only by the body portion having the same diameter.

In such a tandem mill, the plate thickness near the widthwise edge of the rolled metal strip 1 is measured using a plate thickness measuring device 6 at the exit side of the final stage rolling stand 2 and/or the entry side of the first stage rolling stand 2.
The shift position WRδ of the work roll 3 of the rolling stand 2 on the upstream side of the final stage is determined based on this measured value.
It is preferable to correct.

[For production]

When carrying out the method of the present invention using such a tandem mill, the work roll 3 of each rolling stand 2 equipped with a tapered work roll 3 is moved in the axial direction, and the widthwise edge of the rolled metal strip 1 is moved. is positioned at the tapered portion 3a of the work roll 3, and the shift position WRδ of the work roll 3 is set as described below.

First, the taper effect amount Δh to be improved for each rolling stand 2 equipped with a tapered work roll 3 is determined. A constant a determined by the exit plate thickness at the center in the width direction and the roll dimensions of the rolling stand 2.

The value a derived from b, h+b, and work roll 3
It is estimated by the product of the value WRT=100X 2 Xtanθ obtained from the tangent tanθ of the taper angle θ and the shift position [WRδ of the work roll 3, that is, Δh=(ah+b)XWRTXWRδ. That is, in a rolling stand 2 equipped with a tapered work roll 3, the thickness of the exit side plate at the widthwise center of the rolled metal strip 1 and the work roll 3 are
When the rolled metal strip 1 is cold rolled with the taper angle θ constant, the taper effect amount Δh increases in direct proportion to the increase in the shift position WRδ of the work roll 3, as shown in FIG. The taper effect amount Δh when rolling the metal strip 1 to be rolled with the exit side plate thickness at the center in the width direction of the metal strip 1 and the shift position WRδ of the work roll 3 kept constant is the taper effect amount Δh of the work roll 3 as shown in FIG. tangent tan of angle θ
The taper effect amount Δh increases in direct proportion to the increase in θ, and when the metal strip 1 to be rolled is rolled while keeping the taper angle θ of the work roll 3 and the shift position WRδ of the work roll 3 constant, the taper effect amount Δh is shown in FIG. It has been confirmed through experiments that the thickness increases in direct proportion to the increase in the thickness of the exit side plate at the center in the width direction of the rolled metal strip 1. Further, a value a h derived from constants a and b determined by the thickness of the exit side plate at the widthwise center of the rolled metal strip 1 and the roll dimensions of the rolling stand 2.
+b and the value WRT obtained from the tangent tan θ of the taper angle θ of the work roll 3 and the shift position W of the work roll 3
When the taper effect amount Δh obtained from the product with Rδ was compared with the measured value measured on the rolled metal strip 1 at the exit side of the rolling stand 2, it was confirmed that they almost matched as shown in FIG. Ta. At this time, the amount of increase in the interval between the work rolls 3 at a predetermined position near the edge in the width direction of the rolled metal strip 1 is approximated as WRTXWRδ/100, and the plate thickness of the cold rolled rolled metal strip 1 is approximated as WRTXWRδ/100. gradually decreases in a quadratic curve as it goes from the center in the width direction to the edge, and decreases from the edge to 2
Normally, the plate thickness decreases rapidly on the edge side from the 0 mm position, so the taper effect amount Δh at the position 20 mm from the edge
Set. Further, the taper effect amount Δh is defined as the rolled metal strip 1 cold-rolled by a cylindrical work roll 3 in one rolling stand and the rolled metal strip cold-rolled by a work roll 3 formed with a tapered portion 3a. 1, the taper effect amount to be improved from the crown amount at a position 20 os from the edge of the rolled metal strip 1 cold-rolled by the cylindrical work roll 3. Set Δh. This taper effect amount Δ
The setting value of h is set to an appropriate value depending on the rolling ratio, plate thickness, etc., and in order to prevent plate breakage due to increased tension near the plate edge, the range of values is 1% or less of the plate thickness on the exit side. Set within.

Next, a value a h + derived from the outlet thickness h of the rolled metal strip 1 at the center in the width direction, that is, constants a and b determined by the distance between the bodies 3b of the opposing work rolls 3 and the roll dimensions of the rolling stand 2. Derive the value of b. The constants a and b determined by the roll dimensions of the rolling stand 2 vary depending on the roll diameter, roll body length, and distance between roll chocks, but variations in these roll dimensions are small in the same rolling stand. Therefore, for the roll dimensions, an experiment was conducted in which the exit plate thickness was varied while keeping WRδ and WRT constant, and the taper effect amount Δh
For example, in the example described later, a is 0.225, b is o, oso
The above value was obtained as follows.

From the value obtained as above, the shift position W of the work roll 3 is
The relationship described above for Rδ, that is, the taper effect amount Δh is a value a h derived from the constants a and b determined by the exit side plate thickness of the metal strip 1 to be rolled and the roll dimensions of the rolling stand 2.
+b and the tangent tan of the taper angle θ of the work roll 3
Since it is expressed as the product of the value WRT obtained from θ and the shift position WRδ of the work roll 3, which indicates the distance from the edge of the rolled metal strip 1 to the taper start point T0 of the work roll 3, WRδ=Δh/ (( a h+b)XWRT) to be distributed to each rolling stand.

In this setting, since the deformation resistance of the rolled metal strip 1 is low in the first stand, Δh/h (this value is approximately proportional to the increase in tension near the strip edge) is made small, and the rolling stand 2 in the final stage is It is preferable to distribute the taper effect amount Δh so that Δh/h increases sequentially up to the rolling stand 2 immediately before.

At this time, if the shift position WRδ of the work roll 3 cannot be set to a predetermined value due to reasons such as when the width of the rolled metal strip 1 is wide or when the movement range of the work roll 3 in the axial direction is small, etc. To do this, replace the work roll 3 with a tapered portion 3a having a large taper angle θ, set the taper angle θ of the work roll 3, and then set the shift position [WRδ] of the work roll 3 as described above. good.

Although two or more rolling stands 2 are installed to set the shift position [WRδ] of the work roll 3,
In order to reduce the influence of medium elongation on the metal strip, rolling is carried out only by the trunk portion of the work roll 3 having the same diameter in the final stage rolling stand 2, so that the target plate of the final rolled metal strip is Since the thickness improvement amount is not the sum of the taper effect amount Δh obtained by two or more rolling stands located upstream,
The total sum of the taper effect Δh obtained by two or more rolling stands on the upstream side of the rolling stand 2 is set as a target value that takes into account the reduction in the plate thickness near the edge in the width direction of the metal strip at the rolling stand 2 of the final stage. The taper effect amount Δh obtained by each rolling stand is distributed within a range of 1% or less of the exit side sheet thickness so as to be larger than the sheet thickness improvement amount.

In addition, as shown in FIG. 1, the thickness of the rolled metal strip 1 passed through the final stage rolling stand 2 near the edge in the width direction is measured using a thickness measuring device 6, and based on this measurement value, the final By correcting the shift position WRδ of the work roll 3 of the rolling stand 2 on the upstream side of the stage, plate thickness accuracy can be more effectively obtained, and the rolled metal strip to be passed through the rolling stand 2 of the first stage can be improved. 1 is measured near the edge in the width direction by the plate thickness measuring device 6, and based on this measurement value, the shift position WRδ of the work roll of the rolling stand 2 upstream from the final stage is determined.
By correcting this, plate thickness accuracy can be obtained more effectively.

〔Example〕

Example 1 Tapered with a taper angle θ of 2.00 x 10-'rad, body diameter 135III11, body 3b length 850 +w, and distance between chocks 1075 m
The work roll 3 has a body diameter of 300 mm, a body length of 8501011, and a distance between chocks of 16 mm.
The intermediate roll 4 has a diameter of 60 mm, and the body has a diameter of 630 mm.
The body part 3 has a length of 850 am and a backup roll 5 with a distance between chocks of 1475 mm, and has a tapered part 3a formed therein as shown in FIG.
The 6-high rolling stand 2 with one end of b located on the opposite left and right sides is the first stage, and the taper angle θ is 4.00.
X 10-'rad taper, body diameter 135
A work roll 3 having a round body portion 3b having a length of 850+m and a distance between chocks of 1075 mm, and an intermediate roll 4 and a backup roll 5 each having the same dimensions as the first stage six-high rolling stand 2. As shown in FIG. 2, a six-high rolling stand 2 in which one end of the body 3b on which the tapered portion 3a is formed is located on the left and right opposite sides is placed in the second stage, and the taper angle θ is 6.00X. 10-'r
ad tapered, the body diameter is 135 cm, the length of the body 3b is 850 rm, and the distance between chocks is 107 mm.
5 of the work roll 3 and 6 of the first stage, respectively.
It consists of an intermediate roll 4 and a backup roll 5 having the same dimensions as the rolling stand 2, and has a tapered part 3a as shown in FIG.
The third stage is a six-high rolling stand 2 in which one end of the body 3b where the body 3b is formed is located on the opposite left and right sides, and has a diameter of 135 cm, a length of 850 rm, and a distance between chocks of 1075 cm. The final stage is a six-high rolling stand 2 consisting of a cylindrical work roll 3, an intermediate roll 4 having the same dimensions as the first six-high rolling stand 2, and a backup roll 5, as shown in FIG. 4 arranged like
When rolling a 5US304 stainless steel strip with a width of 1220 mm and a thickness of 3.15 mm using a tandem mill on a rolling stand, the thickness at the exit side is 1.01 m.
In order to make the taper effect amount Δh in the first stage rolling stand 2 to 4,38- which is 1% or less of the exit side plate thickness 2.21 mm, the reduction amount W per 100 mm of the diameter of the work roll 3 is
Since RT is 0.04 mm, the shift position WRδ of the work roll 3 is set to 200 mm, and the taper effect amount Δh is set to the exit side plate thickness L, 5 at the second rolling stand 2.
Since the reduction amount WRT per 100 m of the diameter of the work roll 3 is 0.08 m+ in order to make it 6.38 Am, which is a value of 1% or less of 5 mm, the shift position W of the work roll 3 is
Rδ was set to 200 mm, and the diameter of the work roll 3 was 100 mm in order to set the taper effect amount Δh at the third stage rolling stand 2 to 7,30-, which is a value of 1% or less of the exit side plate thickness of 1.13 mm. Since the reduction amount WRT is 0012, the shift position WRδ of work roll 3 is set to 200 m.
Also, the interval between the cylindrical work rolls 3 of the final stage rolling stand 2 is set to 1. As a result of cold rolling with the setting of o1+m, as shown in Fig. 5, the thickness of the stainless steel strip at a position 20 mm from the edge in the width direction to the center side is the same as that of the roll diameter of 135 mm from the first stage to the final stage. It was possible to roll the stainless steel strip about 10 tones thicker than when the stainless steel strip was rolled using the cylindrical work roll 3 under the same conditions.

Example 2 A work roll 3 which is tapered with a taper angle θ of 3.00 x 10-'rad, has a body diameter of 135++++, a length of the body 3b of 850 mm, and a distance between chocks of 11075a, The intermediate roll 4 has a body diameter of 300 cm, a body length of 8501 mm, and a distance between chocks of 1660 cm, and a body diameter of 630 mm and a body length of 8 mm.
It consists of a back-up roll 5 having 50 squares and a distance between chocks of 1475cm, and one end of a body 3b having a tapered part 3a formed thereon as shown in FIG. 2 is located on the left and right opposite sides 6. The high rolling stand 2 is set as the first stage,
Further, a work roll 3 is tapered with a taper angle θ of 5.00 x 10-'rad, has a body diameter of 135+wm, a length of the body 3b of 850cm, and a distance between chocks of 1075cm; It consists of an intermediate roll 4 and a backup roll 5, each of which has the same dimensions as the six-high rolling stand 2 of the first stage, and as shown in FIG. The six-high rolling stand 2 that is attached to the second stage is further tapered with a taper angle θ of 7.00 x 10-'rad,
A work roll 3 having a body diameter of 135 mm, a body part 3b having a length of 850 mm, and a distance between chocks of 1075 m, an intermediate roll 4 and a backup roll each having the same dimensions as the first stage six-high rolling stand 2. 5, and has a tapered portion 3a formed therein as shown in FIG.
A six-high rolling stand 2 with one end of b located on the opposite left and right side is placed in the third stage, and the diameter is 135 mm and the length is 8.
50ill and distance between chocks is 1075m+
The final stage is a six-high rolling stand 2 consisting of a cylindrical work roll 3, an intermediate roll 4 having the same dimensions as the first six-high rolling stand 2, and a backup roll 5, as shown in FIG. A tandem mill with 4 rolling stands arranged as shown in the figure shows a width of 1420m and a thickness of 2.36m.
m (7) When rolling a SUS430 (7) stainless steel strip so that the exit side plate thickness is 0.77 mm, the taper effect amount Δh is set at the first stage rolling stand 2 to the exit side plate thickness 1,
Reduction amount WR of the diameter of work roll 3 per 100 mm to make it 5,08A1m which is 1% or less of 66mm
Since T is 0.06 m+, the shift position WRδ of the work roll 3 is set to 200 m, and the taper effect amount Δh is set to 1 for the exit side plate thickness of 1.16 mm.
% or less, the reduction amount WRT per 100 mm of the diameter of the work roll 3 is 0.10 + m.
Therefore, the shift position WRδ of the work roll 3 is set to 200.
Set to ma+.

Further, the taper effect amount Δh in the third stage rolling stand 2 is set to a value of 1% or less of the exit side plate thickness 0.135 mm + 6, 76,
Since the reduction amount WRT per 100 of the diameter of the work roll 3 is 0.14 m, the shift position WRδ of the work roll 3 is set to 200 m, and the cylindrical workpiece of the final stage rolling stand 2 is Roll 3 spacing 0.7
As a result of cold rolling with a setting of 7 mm, the width of the stainless steel strip from the edge in the width direction to the center is 201 m1+, as shown in Figure 5.
The plate thickness at the position from the first stage to the final stage is approximately 10 times higher than that when the stainless steel strip described above is rolled under the same conditions using a cylindrical work roll 3 with a roll diameter of 135 m.
- It was possible to roll thickly.

〔Effect of the invention〕

When the method of the present invention is carried out as detailed above, the taper effect amount indicating that the rolled metal strip cold-rolled by the tandem mill has a good shape at each rolling stand is as follows.
A desired value can be achieved by setting the shift position of the work roll by a simple operation of moving the work roll in the axial direction, and the shift position of the work roll can be appropriately set before rolling. Therefore, the taper effect amount can be easily controlled when changing the plate width, exit side plate thickness, etc., and work efficiency is greatly improved. In addition, if the work roll shift position cannot be set to a predetermined value due to reasons such as when the width of the metal strip to be rolled is wide or when the movement range of the work roll in the axial direction is small, the taper angle may be changed. By replacing the work roll with a different work roll, setting the taper angle of the work roll, and then setting the shift position of the work roll to a predetermined value, it is possible to easily correspond to various rolling mills.

Further, in the final stage rolling stand, a rolling stand is installed in which a work roll having a tapered part is installed, and the metal strip to be rolled is rolled only by the body part of this work roll having the same diameter, or the metal strip to be rolled is rolled into a cylindrical shape. By arranging a rolling stand equipped with work rolls, and rolling the metal strip to be rolled using these cylindrical work rolls, it is possible to reduce the influence of elongation on the metal strip and to roll it into a good shape. can.

In addition, if the thickness of the rolled metal strip near the edge in the width direction is measured at the exit side of the final stage rolling stand or the entry side of the first stage rolling stand, the thickness of the rolled metal strip can be measured by changing the rolling conditions, etc. The shift position of the work rolls can be easily adjusted to changes in thickness during rolling, and rolling can be more effectively performed with excellent sheet thickness accuracy.

The method of the present invention, which allows metal strips with excellent plate thickness accuracy to be efficiently rolled using various rolling mills, makes a major contribution to the field of steel manufacturing, and has great industrial value. It is.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of a tandem mill in which three rolling stands each having a tapered work roll are arranged in front of the final rolling stand for carrying out the method of the present invention; Figure 2 is an explanatory cross-sectional view taken along line A-A in Figure 1;
Fig. 3 is an enlarged explanatory view of part B in Fig. 2, and Fig. 4 shows a predetermined position from the edge in the width direction of a metal strip cold-rolled on one rolling stand equipped with tapered work rolls. A diagram showing the relationship between the measured value and the value obtained from the formula for the amount of taper effect. Figure 5 shows a metal strip and a cylindrical workpiece that were cold-rolled by the method of the present invention using the tandem mill shown in Figure 1. Figure 6 shows the distribution of sheet thickness deviation with respect to the center in the width direction for metal strips cold-rolled by a tandem mill equipped with four rolling stands equipped with rolls. A diagram showing the relationship between the taper effect amount and the shift position of the work roll when a metal strip to be rolled is cold-rolled with the exit side plate thickness and the taper angle of the work roll constant on one rolling stand equipped with a work roll. , Figure 7 shows the taper effect amount and workpiece when a metal strip to be rolled is cold-rolled on one rolling stand equipped with tapered work rolls with the exit side thickness and work roll shift position constant. Figure 8 is a diagram showing the relationship between the taper angle of the roll and the tangent. It is a figure which shows the relationship between the taper effect amount and exit side plate thickness when cold rolling is carried out at a constant value. In the drawings 1... Metal strip to be rolled 2... Rolling stand 3... Work roll 3a... Taper part 3b... Body part 4... Intermediate roll 5...・Backup roll 6...Plate thickness measuring device To...Taper start point θ...Work roll taper angle WRδ...Work roll shift position WRT...
・Diameter reduction per loom of tapered part of work roll

Claims (1)

[Scope of Claims] 1. A pair of work rolls each having a tapered portion formed at one end of its body, facing each other with the tapered portions located on left and right opposite sides, and facing each other in the axial direction. When a metal strip to be rolled is cold rolled by a tandem mill in which two or more rolling stands are movably installed in the upstream side of the final rolling stand, each of the rolling stands At the same time, the width direction edge of the rolled metal strip is positioned on the tapered part of the work roll, and the constants (a, b) determined by the exit side plate thickness (h) of the rolled metal strip and the roll dimensions of each rolling stand are set. (ah+b) and the value (WRT) derived from the tangent (tanθ) of the taper angle (θ) of the tapered part of the work roll WRT=100×2×tanθ Work roll shift position (WRδ) indicating the distance to the roll taper start point
The shift position (WRδ) of the work roll is set within a range where the taper effect amount (Δh) expressed as the product of Δh=(ah+b)×WRT×WRδ is 1% or less of the exit side plate thickness (h). A crown control method in cold rolling using a tandem mill, which is characterized by moving a work roll in its axial direction to set the distribution. 2. When setting the shift position (WRδ) of the work roll, the work roll is moved in the axial direction after setting the taper angle (θ) of the work roll to set the shift position (WRδ) of the work roll. Crown control method in cold rolling using a tandem mill described in . 3 A rolling stand equipped with a tapered work roll is installed as the final stage rolling stand, and the metal strip to be rolled is rolled only by the body portion having the same diameter of the tapered work roll. The tandem mill according to claim 1 or 2, wherein a rolling stand is provided with a cylindrical work roll and the metal strip to be rolled is rolled by the cylindrical work roll. Crown control method in cold rolling. 4 Measure the thickness near the edge in the width direction of the rolled metal strip passed through the final stage rolling stand, and based on this measurement, determine the shift position ( The crown control method in cold rolling by a tandem mill according to any one of claims 1 to 3, wherein WRδ) is corrected. 5. Measure the thickness near the edge in the width direction of the rolled metal strip to be passed through the first stage rolling stand, and based on this measurement, determine the shift position (WRδ) of the work roll of the rolling stand upstream from the final stage. ) The crown control method in cold rolling by a tandem mill according to any one of claims 1 to 4.