JPS645963B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the shape of a rolled material. More specifically, the present invention calculates the plastic strain component of the plate strain caused by the coil crown of the metal material wound after cold rolling, and adjusts the tension of the rolled material to compensate for the plastic strain component. The present invention relates to a method of controlling distribution and providing a metal plate with high flatness.

Conventionally, in rolling metal materials, measuring rolls have been used as shape detection means for shape control, and control means include changing the bending position of the work roll, changing the rolling position with a rolling cylinder, or changing the width of the coolant in the plate width direction. The amount of ejection was adjusted.

As is well known, the measuring roll is composed of a plurality of rolls with built-in transducers divided in the width direction of the sheet, and measures the stress in each zone in the width direction of the sheet. Based on these detected stress distributions,
The stress distribution, ie, the strain distribution, in the plate width direction has been controlled with respect to the control target value by roll bending or by correcting the coolant ejection amount distribution in the plate width direction or the rolling position.

However, in the conventional method described above, the strain distribution in the width direction of the rolled material is simply controlled to be constant after rolling, that is, before winding. Furthermore, it does not control the strain distribution in the rewound state.

The present inventors measured the stress distribution of pure Al material (A1050) immediately after cold rolling and after coiling to investigate the shape change in the sheet width direction, and the results are shown in Figures 1a and 1b. .

FIG. 1a shows the distribution of stress deviation values in the width direction of the rolled material in the inner winding portion of the wound coil. As shown in FIG. 1a, the stress deviation in the plate width direction in the plate material of the inner winding portion of the coil is small and within the allowable range.

On the other hand, although almost no stress deviation is observed in the plate material of the outer coil part shown in Figure 1b immediately after rolling, a large stress distribution is observed in the width direction of the plate material after winding. It was done. In other words, it can be seen that in the plate material of the outer winding part, the center part of the plate width is extended with respect to the edge part of the plate width, and is in a so-called medium elongation state.

The present inventors presumed that this shape change in the width direction of the coil after winding was caused by coil winding, and investigated the effects of the coil diameter and winding tension on the shape change in the width direction. , the results are shown in FIGS. 2 and 3.

Figures 2 and 3 illustrate the shape change in the width direction of the plate material in the outer winding section with respect to the diameter of the winding coil ^.
Figure 3 shows the case of a coil wound at 2.50Kg/ ^mm2 .

As shown in Figures 2 and 3, although there is almost no shape change in the width direction of the rolled material immediately after rolling, that is, before winding, when the coil diameter exceeds 900 mm after winding, A shape change in the width direction of the rolled material is observed during mid-elongation in proportion to the coil diameter. Further, when comparing FIG. 2 and FIG. 3, it is clear that when the material is wound with the low tension shown in FIG. 3, the rate of change in shape is small, and the winding tension has a large influence on the change in shape.

The present inventors investigated the mutual relationship between the plate crown and the coil crown, since the shape change after winding is thought to be influenced by the coil crown (the coil exhibits a drum shape) due to the overlapping of the plate crowns of the rolled material. . The results are shown in Figures 4a, b, c, and d. The sample material is pure Al (A1050) material, and in each case, the plate crown is about 1.2% of the plate crown of about 1.1%.
It shows a drum shape with medium height. When a rolled material is wound into such a drum-shaped coil, the tension distribution in the width direction of the strip exhibits a particularly large value at the center of the strip width, and the shape change is thought to be caused by this.

Therefore, conventional shape control methods that do not consider the influence of the coil crown cannot eliminate the strain in the width direction of the rolled material as described above.

Therefore, the present invention aims to solve the problems of the prior art mentioned above.

More specifically, the present invention provides a shape control method that makes it possible to obtain a rolled material with little change in shape in the sheet width direction even after winding.

According to the present invention, in a method of detecting the shape of a metal material that is rolled and wound under a predetermined tension using a shape detector, and adjusting the width direction tension of the rolled material based on the detected value to control the shape. Find the coil crown of the coil to be wound from the plate crown of the rolled material, calculate the plate strain after winding caused by the coil crown, and calculate the plastic strain of the above strain from the stress-strain diagram of the rolled plate. The stress corresponding to the plastic strain is calculated, and the tension in the width direction of the plate is controlled so that the tension distribution detected by the shape detector becomes the tension distribution corrected for the stress, so that the plate is flat after winding. A method for controlling the shape of a rolled material is provided, the method comprising obtaining a plate.

Examples of means for adjusting the tension distribution include changing the roll bending position or the position of the reduction cylinder, and adjusting the amount of coolant ejected in the plate width direction.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

According to the research of the present inventors, the strain distribution in the width direction of the rolled material is due to the strain distribution due to rolling, the strain caused by the difference in trajectory length of the rolled material in the width direction between the take-up coil and the deflector roll immediately before it. distribution, strain distribution due to creep of the rolled material, and strain distribution due to the above-mentioned winding coil crown.

Among these, the strain distribution due to rolling has conventionally been detected by a shape detector, and has been conventionally carried out by adjusting roll bending and rolling cylinders, or adjusting the amount of coolant ejected in the width direction of the plate.

Furthermore, the strain distribution due to the difference in trajectory length is at most about 0.00025% even considering the current crown of the take-up roll and deflector roll, which is much smaller than the measurement accuracy of the shape detector. ignore.

Furthermore, regarding the strain distribution due to creep in the rolled material, depending on the rolling temperature and material, the influence of creep after winding cannot be ignored in some cases, but this is not considered in the method of the present invention.

Therefore, the present invention takes into consideration the strain distribution in the width direction of a rolled material due to the winding coil crown, and provides a shape control method for eliminating this strain distribution.

Figures 5a and 5b show cross-sections of the wound coil and rolled material, respectively.

The crown Sc of the rolled material is expressed by the following equation based on the geometric shape of the cross section.

Sc=hc-he/hc (1) However, hc is the thickness at the center of the plate width, he is the thickness at the edge of the plate width, and the winding coil is formed by winding the rolled material N times, so the following formula holds: do.

D=2Nhe+d (2) D+2△=2Nhc+d (3) However, D is the outer diameter of the coil end. d is the inner diameter of the coil △R is the coil crown amount The following equation can be obtained from the above equations (1), (2), and (3).

△R=(D-d)Sc/2(1-Sc) (4) Equation (4) assumes that the crown Sc of the rolled material is stacked N times to form the wound coil crown △R. Due to the rigidity of the rolled material, the ends do not overlap exactly. Therefore, it is necessary to actually measure the amount of winding crown for each material, find the correction coefficient α for the above-mentioned theoretical value, and correct it. Equation (4) is corrected by the correction coefficient α as follows.

△R=(D-d)Sc/2(1-Sc)・α (5) As a result, the strain generated during winding of the rolled material is calculated by the following formula:
Obtained by (6) ε ₂ =2△R/D=(D-d)Sc/D(1-Sc)
・α(6) Here, it is the plastic strain ε ₂ p of the above strain ε ₂ that becomes a problem during the final use of the rolled material. Therefore,
The plastic strain ε ₂ P is determined from the stress-strain diagram of the material after rolling. As shown in FIG. 6, the plastic strain ε ₂ P corresponds to the point where a straight line is drawn from the point ε ₂ on the stress-strain curve with an inclination corresponding to the elastic modulus of the material, and the line intersects with the axis in the strain direction.

A shape control method for compensating for distortion caused by the coil crown will be described with reference to FIG.

First, the crown ratio Sc, crown shape, and coil crown coefficient α of the rolled material are determined based on previously measured values or assumptions for a similar rolled material.

Next, the coil diameter is calculated based on the number of rotations of the shape detection roll and the thickness of the rolled material.

Based on these values, for each predetermined section i in the width direction of the rolled material, the coil crown distribution △Ri, the strain distribution after winding ε ₂ i, and the stress distribution after winding σ ₂ i = σ (ε ₂ i) and the plastic strain distribution ε ₂ pi. Here, the plastic strain ε ₂ pi is obtained by obtaining the stress distribution σ ₂ i from the stress-strain curve as described above,
From this, it can be found using the following formula.

ε ₂ pi=ε ₂ i−σ ₂ i/E (6) where E indicates the elastic modulus of the rolled material.

Next, the stress distribution σ ₂ si corresponding to the plastic strain ε ₂ pi is determined from the stress-strain curve, and the tension distribution target value of the shape detector is corrected according to the following equation.

i*=σi*+σ ₀ −σ ₂ pi (7) Here, i* is the tension distribution target value of the shape detector, σi* is the stress of the rolled material in the i-th area, and σ ₀ is the average stress.

FIG. 8 is a schematic diagram of an apparatus for carrying out the method of the present invention by adjusting the roll bending position and the amount of coolant jetted.

After the rolled material 1 is rolled in a finishing rolling stand 2, it passes through a shape detection roll (also functioning as a deflector roll) 3 immediately before being wound up in a winder (not shown). The stress distribution σi* in the width direction detected by the detection roll 3 is input to the CPU 4.
The CPU calculates σ ₂ pi using the procedure shown in Figure 7, and calculates i
* is output to the control device 5.

The control device 5 operates the roll bending actuating device 6 and the coolant actuating device 7, and adjusts the amount of roll bending and the distribution of coolant in the width direction of the rolled material so that the target stress distribution σi* is achieved.

Example The method of the present invention was applied to a rolling method in which pure Al material (A1050) was rolled down from a thickness of 1.13 mm to 0.65 mm and wound into a coil.

It was assumed that the crown ratio of the rolled material was 1%, the crown distribution in the sheet width direction was a quadratic curve, and the crown correction coefficient was α = 0.48.

Furthermore, the stress-strain curve was approximated by the following formula.

σ(ε)=7000×ε/100 (ε≦0.144%) σ(ε)=10.08+233.0 ³ −191.6 ² +54.77 However=ε−0.144(0.144%ε0.48%) σ(ε)= 70.9/100 (ε-0.48) + 15.69 (30.48%
) However, ε is expressed as a percentage.

Based on the above data, divide the board width into 20 equal parts and
Calculate the plastic strain distribution in the plate width direction using the procedure shown in the figure.
The results are shown in FIG.

The target value * was calculated for each winding coil diameter so that the cross-sectional shape of the rolled material was flat (ie, σi*=0), and the results are shown in FIG.

The roll bending position and the amount of coolant were adjusted according to * determined as above, and as a result, a rolled material coil with an extremely flat cross-sectional shape was obtained.

[Brief explanation of drawings]

Figures 1a and 1b show the stress distribution in the width direction of the inner and outer winding parts of the rolled material winding coil before and after winding, respectively. FIG. 2 shows the relationship between the change in the elongation rate in the width direction and the coil diameter before and after winding of the rolled material. FIG. 3 is a graph similar to FIG. 2 when winding is performed with the front tension of the winder being reduced. Figures 4a, b, c and d show a comparison of the rolled material crown and the wound coil crown. FIG. 5a shows a cross section of the wound coil, and FIG. 5b shows a cross section of the rolled material. FIG. 6 shows the stress-strain curve of the rolled material. FIG. 7 is a flowchart of a method for determining a target tension distribution value according to the present invention. FIG. 8 is a schematic diagram of an apparatus for carrying out the method of the invention.
FIG. 9 shows the results of determining the plastic strain distribution in the width direction of a wound coil of a rolled material for each coil diameter according to the present invention. FIG. 10 shows the results of determining stress distribution target values for each coil diameter to compensate for the plastic strain distribution shown in FIG. 8.

Claims (1)

[Claims] 1. The shape of the metal material being rolled and wound under a predetermined tension is detected by a shape detector, and the shape is controlled by adjusting the widthwise tension of the rolled material based on the detected value. In the method; the coil crown of the coil to be wound is determined from the plate crown of the rolled material, the plate strain after winding caused by the coil crown is calculated, and the stress-strain diagram of the rolled plate is used to determine the amount of the above distortion. Find the plastic strain of the sheet, calculate the stress corresponding to the plastic strain, control the tension in the width direction of the sheet so that the tension distribution detected by the shape detector is the tension distribution corrected for the stress, and then wind the sheet. A method for controlling the shape of a rolled material, characterized by obtaining a flat plate. 2. The method for controlling the shape of a rolled material according to claim 1, characterized in that the tension distribution in the width direction of the sheet is controlled by changing the roll bending position of the rolling mill. 3. The rolled material according to claim 1, wherein the tension distribution in the width direction of the plate is controlled by changing the amount of spray in the width direction of the coolant jetting means attached to the rolling mill. shape control method.