JPH0459110A - Control method of crown in cold rolling - Google Patents

Abstract

PURPOSE:To improve work efficiency by specifying the moving amount of work roll in the axial direction and controlling the quantity of taper effect in the crown control of cold rolling. CONSTITUTION:At the time of crown control in cold rolling, the quantity ( h) of taper effect is calculated by the equation. Where, (ah + b) is taken as a constant that is determined by the dimensions of the roll of rolling mill, WRT as a value that is determined by the taper angle (theta) of work roll, WRdelta as the shift position of work roll. The work roll is moved in the axial direction and set so that the quantity of taper effect is <=1% of the thickness (h) on the outlet side. In this way, the shift position of work roll can be adequately set before rolling and work efficiency is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for cold rolling a metal strip using a work roll having a tapered end at one end of the side portion. This invention relates to a crown control method in cold rolling that can uniformly control the sheet thickness distribution in the direction, grasp the control amount, and roll the sheet into a good shape with high thickness accuracy in the width direction.

[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, in 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. Because the metal strip is rolled by roll bending, the work roll comes into strong contact with the metal strip, especially near the edges in the width direction, resulting in the strip being rolled into a shape in which the thickness of the strip is sharply reduced near the edges in the width direction. This is because it will be done.

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.

Therefore, a tapered part is formed at one end of the left and right opposite sides of each of the opposing work rolls, and the edge of the metal strip to be rolled is formed between the taper start point and the end point of the taper part. A rolling method has been proposed that suppresses the decrease in thickness near the edges in the width direction of the metal strip and improves the accuracy of the thickness by cold rolling the metal strip in the widthwise direction. 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 roll increases, so the thickness of the metal strip at the tapered part decreases in the width direction of the metal strip. This is because the thickness is suppressed compared to the central portion, and the thickness shape of the metal strip as a whole becomes better.

However, when carrying out the above-described rolling method, if the set value of the distance from the widthwise edge of the metal strip to the taper start point of the work roll is not appropriate, the shape of the cold-rolled metal strip may be defective and the metal strip may A phenomenon occurs in which the plate thickness shape is not good as a whole. Therefore, 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. Since the distance from the edge to the start point of the work roll's taper was set, the extent to which the thickness of the widthwise edge of the cold-rolled metal strip was improved by the method described above could only be determined after rolling. In order to obtain the target thickness accuracy, the distance from the edge of the metal strip in the width direction to the taper start point of the work roll must be accurately set in advance, resulting in a decrease in yield. Moreover, there was a drawback that working efficiency was reduced.

[Problem to be solved by the invention]

The present invention solves the above-mentioned drawbacks of the prior art, and allows the setting of the distance from the taper start point of a work roll tapered at one end of the side part to the edge of the rolled metal strip to a desired value. It is possible to preset the setting value to obtain plate thickness accuracy.

It is an object of the present invention to provide a method for controlling crown in cold rolling that improves yield and is excellent in work 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 using a cylindrical work roll and when the rolled metal strip is cold-rolled using a work roll that is tapered at one end of the side part. 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 mill in which a tapered part is formed at one end of the left and right opposite sides 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 from the tangent tan θ of the taper angle θ of the work rolls.
= 100 X 2 )/
It can be approximated as a value of 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 tapered part on the fine deflection of the work rolls, the amount of increase in thickness at the exit side is calculated from the amount of increase in the distance 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 flatness of the rolls, and the amount of increase in thickness on the exit side is approximately proportional to the amount of increase in the interval between 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 approximately proportional to the amount of increase in tension described above, and has almost no relation to other rolling conditions.

From the knowledge of the above 0 to 0 terms, the value a h+b derived from the exit side plate thickness at the widthwise center of the rolled metal strip and the constants a and b determined by the roll dimensions of the rolling mill and the taper angle θ of the work roll The taper effect amount Δh, that is, Δh, is determined by the product of the value WRT obtained from the tangent tanθ of
= (ah ten b) X W RT X W R
They completed the present invention by discovering that δ can be estimated.

The method of the present invention will be explained in detail below with reference to one drawing.

FIG. 1 is a side explanatory view showing an example of the roll arrangement of a rolling mill suitable for carrying out the method of the present invention, and FIG. )
FIG. 3 is an enlarged explanatory view of section A in FIG. 2, and FIG. 4 is a taper at a predetermined position from the edge in the width direction of a metal strip cold-rolled by the method of the present invention. A diagram showing the relationship between the measured value and the value obtained from the formula for the effect size, Figure 5 shows a metal strip cold-rolled by implementing the method of the present invention and a metal strip cold-rolled by a cylindrical work roll. Fig. 6 shows the distribution of the thickness deviation with respect to the widthwise central part, respectively, and Fig. 6 shows the taper effect amount and workpiece when the rolled metal strip is cold rolled with the exit side plate thickness and the taper angle of the work roll constant. Figure 7 shows the relationship between the roll shift position and the tangent of the taper effect and the work roll taper angle when a rolled metal strip is cold rolled with the exit side thickness and work roll shift position constant. Figure 8 is a diagram showing the relationship between the taper effect amount and the exit side plate thickness when a rolled metal strip is cold rolled with the work roll taper angle and work roll shift position constant. It is.

To carry out the method of the present invention, first, as shown in FIGS. 1 to 3, a work roll 2 is formed, each having a tapered portion 2a at one end of each side thereof.
However, the work rolls 2 for preparing the rolling mill whose tapered portions 2a are located on opposite left and right sides and are opposed to each other are as follows.
The heel from the taper start point T, which is the boundary point between the side portion 2b and the tapered portion 2a having the same diameter, to the edge in the width direction of the rolled metal strip 1, that is, the shift position WRδ of the work roll 2
It is installed movably in the axial direction so that it can be set to a predetermined value.

As shown in FIGS. 1 and 2, a rolling mill equipped with such work rolls 2 has work rolls 2 on both sides of the metal strip 1 to be rolled, and an intermediate roll on the outside of the work rolls 2. In addition to a six-high rolling mill in which one set of backup rolls 4 are each installed on the outside of the six-high rolling mill, various rolling mills such as a cluster mill and a Sendzimya mill can be used.

[For production]

When carrying out the method of the present invention using such a rolling mill, the work roll 2 is moved in the axial direction so that the widthwise edge of the rolled metal strip 1 is positioned at the tapered portion 2a of the work roll 2, and The shift position WWRδ is set as explained below.

First, the taper effect amount Δh to be improved is determined.
As described above, the taper effect amount Δh is the value a h + derived from the thickness of the outlet side of the rolled metal strip 1 at the center in the width direction and the constants a and b determined by the roll dimensions of the rolling mill.
b and the tangent tanθ of the Taber angle θ of the work roll 2 WRTWRT=100X 2 Xtan
The product of θ and the shift position WRδ of the work roll 2, that is, Δh = (ah + b) X W RT
Estimated by W Rδ. That is, the taper effect amount Δh when the rolled metal strip 1 is cold-rolled with the exit side plate thickness at the widthwise center of the rolled metal strip 1 and the taper angle θ of the work roll 2 constant in a cold rolling mill consisting of As shown in FIG. 6, increases in direct proportion to the increase in the shift position [WRδ] of the work roll 2, and increases the thickness of the exit side plate at the widthwise center of the rolled metal strip 1 and the shift position W of the work roll 2.
When rolling the metal strip 1 with Rδ constant, the taper effect amount Δh increases in direct proportion to the increase in the tangent tanθ of the Taber angle θ of the work roll 2, as shown in FIG. When the metal strip 1 to be rolled is rolled with the taper angle θ and the shift position WWRδ of the work roll 2 constant, the taper effect amount Δh is determined by the thickness of the exit side plate at the widthwise center of the metal strip 1 to be rolled, as shown in FIG. It was confirmed through experiments that this increases in direct proportion to the increase in . Furthermore, the value WRT obtained from the value ah+b derived from the exit side plate thickness at the widthwise center of the rolled metal strip l and the constants a and b determined by the roll dimensions of the rolling mill and the tangent tanθ of the Taber angle θ of the work roll 2. The taper effect amount Δh obtained from the product of the shift position WRδ of the work roll 2 and the measured value measured after cold rolling the rolled metal strip 1 were compared, and as shown in FIG. 4, they almost matched. It was confirmed that there is. At this time, the amount of increase in the distance between the work rolls 2 at a predetermined position near the edge in the width direction of the rolled metal strip 1 is W
It is approximated as RTXWRδ/100, and the thickness of the cold-rolled metal strip 1 gradually decreases in a quadratic curve from the center in the width direction of the metal strip toward the edge, and is approximately 20 mm from the edge. Normally, the plate thickness decreases rapidly closer to the edge, so in this example, 2011I11 from the edge
The taper effect amount Δh at the position is set. Further, the taper effect amount Δh is determined near the widthwise edge of the rolled metal strip 1 cold-rolled by a cylindrical work roll and the rolled metal strip 1 cold-rolled by a work roll 2 formed with a tapered portion 2a. Since the plate thickness difference is , the taper effect amount Δh to be improved is set from the crown amount at a position 20- from the edge of the rolled metal strip 1 rolled by a cylindrical work roll. This taper effect amount Δh is set to an appropriate value depending on the rolling ratio, plate thickness, etc., and is set to 1% or less of the exit side plate thickness in order to prevent plate breakage due to increased tension near the plate edge. Set to value.

Next, the value h+b, which is derived from the exit side plate thickness h at the widthwise center of the rolled metal strip 1, that is, the distance between the side portions 2b of the opposing work rolls 2 and constants a and b determined by the roll dimensions of the rolling mill. Deduce. The constants a and b determined by the roll dimensions of this rolling mill vary depending on the roll diameter, roll body length, and distance between roll chocks, but in the same rolling mill, these roll dimensions vary little. Therefore, the roll size can be determined by conducting an experiment in which WRδ and WRT are kept constant and the outlet plate thickness is varied, and the taper effect amount Δh is measured at that time.For example, in the example described later, a The above values were obtained by setting b to 0.225 and b to 0.050.

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

At this time, if the shift position WRδ of the work roll 2 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 2 in the axial direction is small, etc. In this case, the work roll 2 may be replaced with a tapered portion 2a having a large taper angle θ, the taper angle θ of the work roll 2 may be set, and the shift position WRδ of the work roll 2 may be set as described above. .

〔Example〕

Example 1 Tapered with a taper angle θ of 8.5 x 10-' rad, side diameter 135 nn, and length of side 2b 850 mm.
, rm, and the distance between chocks is 11075n.

The intermediate roll 3 has a side diameter of 300 mm, a side length of 850 mm, and a distance between chocks of 1660 mm, and a side diameter of 630 mm, a side length of 850 mm, and a distance between chocks. A 6-high rolling mill consisting of a backup roll 4 with a distance of 1475 m++ and one end of the tapered side part located on the opposite left and right sides as shown in FIGS. Plate thickness 1.8
When rolling an 8-inch 5US304 stainless steel strip to a thickness of 1.13 mm on the exit side, the taper effect amount Δh at a position 20 mm from the edge in the width direction to the center of the stainless steel strip is calculated as the thickness of the exit side plate. In order to set the shift position WRδ of the work roll 2 to 10.34 pM, which is 1% or less, since the reduction amount WRT per 100 mm of the diameter of the work roll 2 is 0.17 mm, the shift position WRδ of the work roll 2 is set to 2001. As a result of cold rolling, a cylindrical work roll 2 with a roll diameter of 135 mm is obtained at a position 20 m from the widthwise edge of the stainless steel strip toward the center, as shown in FIG.
This made it possible to roll the stainless steel strip about 11p thicker than when the stainless steel strip was rolled under the same conditions. This value was shown to be approximately the same as the target taper effect amount Δh of 10.34-.

Example 2 Tapered with a taper angle θ of 17.00 x 10'-4 rad, side diameter 135 cm, length of side 2b 8
The work roll 2 has 50 rolls and the distance between chocks is 1075m+, and the side diameter is 300cm and the side length is 8.
The intermediate roll 3 has a diameter of 50 mm and a distance between chocks of 1660 mm, and a side diameter of 630 mm and a side length of 85 mm.
0 nwn and a backup roll 4 with a distance between chocks of 1475 mm, and one end of the tapered side part is located on the opposite left and right sides as shown in FIGS. 1 and 2. Depending on the machine, plate width 1220
mm.

When cold rolling a 5US430 stainless steel strip with a plate thickness of 1.88 m to an exit plate thickness of 1.13 mm,
20Q from the width direction edge of this stainless steel strip to the center side
In order to set the taper effect amount Δh at the position I11 to 10.344, which is a value that is 1% or less of the exit side plate thickness, the reduction amount WRT per 100 strokes of the diameter of the work roll 2 is 0.
34nwn, so the shift position WR of work roll 2 is
As a result of cold rolling with δ set in the order of 100, as shown in Fig. 5, 20
It was possible to roll the stainless steel strip about 114 mm thicker than when the stainless steel strip described above was rolled under the same conditions using the cylindrical work roll 2 with a roll diameter of 135 m+ at the center position. This value showed that it was approximately the same value as 10.34/j11, which was the target taper effect amount Δh.

〔Effect of the invention〕

When the method of the present invention is carried out as detailed above, the taper effect, which indicates that the cold-rolled metal strip has a good shape, can be improved by simply moving the work roll in the axial direction. The desired value can be set by setting the shift position of the rolls, and the shift position of the work rolls can be appropriately set before rolling, so the taper effect can be achieved when changing the width of the plate, changing the thickness of the exit side plate, etc. The amount can be easily controlled, greatly improving work efficiency. 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. If you replace the work roll with a different work roll, set the work roll's Taber angle, and then set the work roll shift position to the specified value,
It can be easily adapted to various rolling mills.

The method of the present invention, which enables efficient rolling of various metal strips with excellent plate thickness accuracy using a cold rolling mill, will make a major contribution to the field of steel manufacturing, and its industrial value will be enormous. It's a big one.

[Brief explanation of drawings]

FIG. 1 is an explanatory side view showing an example of the roll arrangement of a rolling mill suitable for carrying out the method of the present invention, FIG. 2 is an explanatory view of a vertical cross-section along the center line in FIG. FIG. 4 is an enlarged explanatory view of part A in FIG. Figure 5 shows the distribution of sheet thickness deviation with respect to the widthwise central portion of a metal strip cold-rolled by the method of the present invention and a metal strip cold-rolled by a cylindrical work roll, respectively. Figure 6 is a diagram showing the relationship between the taper effect amount and the shift position of the work roll when a rolled metal strip is cold rolled with the exit side plate thickness and the taper angle of the work roll being constant, and Figure 7 is a diagram showing the relationship between the taper effect amount and the shift position of the work roll. Figure 8 is a diagram showing the relationship between the taper effect amount and the tangent of the Taber angle of the work roll when the rolled metal strip is cold rolled with the exit side plate thickness and the work roll shift position constant. FIG. 3 is a diagram showing the relationship between the taper effect amount and the exit side plate thickness when cold rolling is performed with the taper angle of the work roll and the shift position of the work roll kept constant. In the drawings 1... Rolled metal strip 2... Work roll 2a... Taper part 2b... Side part 3... Intermediate roll 4... Backup roll To... - Taper start point θ... Taper angle WRδ of work roll... Shift position WRT of work roll...
・Amount of diameter reduction per 100+m of work roll taper part 1'1 Figure 102 Figure T. Taber effect amount obtained from the diagram diagram Work roll shift position Diagram Thickness deviation with respect to the central part in the axial direction tangent to the Taber angle of the work roll Diagram Output side thickness

Claims (1)

[Scope of Claims] 1. A pair of work rolls each having a tapered portion formed at one end of its side portions, the tapered portions being located on left and right opposite sides, facing each other, and facing each other in the axial direction. When rolling a metal strip to be rolled with the widthwise edge of the metal strip being positioned in the tapered part of the work roll by a rolling mill that is movably installed in the rolling mill,
The value (a,
h+b) and the taper angle (
The value (WRT) W obtained from the tangent (tanθ) of θ)
RT=100×2×tanθ and the shift position of the work roll (WRδ), which indicates the distance from the edge of the metal strip to be rolled to the taper start point of the work roll.
The shift position (WRδ) of the work roll is adjusted so that the taper effect amount (Δh) expressed as the product of A crown control method in cold rolling, characterized in that the crown is set by moving it in its axial direction. 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 described in .