JP2776937B2 - How to prevent meandering of steel strip - Google Patents

Description

The present invention relates to a method for preventing meandering of a steel strip passing through continuous annealing equipment, plating equipment, and the like.

[Prior Art] In a continuous annealing furnace often used for annealing a steel strip, the steel strip is supported by a large number of hearth rolls disposed in the furnace. When the steel strip meanders left and right in the width direction of the hearth roll in such a continuous annealing furnace, not only does the stability of the threaded sheet deteriorate, but also the steel strip contacts the furnace wall,
In the worst case, it may cause a trouble of breaking in a high-temperature furnace.

Such a meandering phenomenon is caused by a variation in the shape of the joint portion and the right and left of the steel strip, and is likely to occur when the speed of the line is increased or the threading tension is reduced.

On the other hand, it is generally known to use a convex crown roll having a bulge at the center of the width, which has a self-correcting effect of meandering, as the roll.

This is based on the phenomenon that when a steel strip is wound around a tapered roll, the steel strip rises in the direction of the larger roll diameter. A balanced state is maintained by the balance of the forces (hereinafter, referred to as restoring forces) at which both ends move.

The amount of movement increases as the taper angle increases, which means an increase in restoring force, and meandering can be prevented if a sufficiently large convex crown roll can be adopted.

However, when a large convex crown roll is actually used, the size of the convex crown is strictly limited because buckling flaws caused by a drawing phenomenon called a heat buckle occur due to an increase in the restoring force from both ends of the roll. Let me.

For this reason, the size of the convex crown has been reduced to the limit where heat buckle does not occur in practical use,
At present, it is not possible to enjoy the strong meandering prevention effect of the convex crown.

Currently, the meandering prevention mechanism that is in practical use,
Alternatively, a roll tilting method of tilting forward and backward is used. This method has a large meandering correction capability, but the difference in tension between the right and left roll widths during meandering correction is large. Flaws and wrinkles are likely to occur and practical application is extremely difficult.

Japanese Patent Application Laid-Open No. Sho 62-158827 discloses a method of correcting the meandering of a steel strip by blowing gas into a contact portion between the steel strip and a roll. In this method, the meandering correction force under high tension is insufficient, and the appearance of a more effective meandering correction method is expected.

[Problem to be Solved by the Invention] The present invention provides a meandering prevention method for preventing a steel strip from being scratched or wrinkled in a continuous annealing facility, a plating facility, etc., and for establishing a stable threading condition. is there.

Means for Solving the Problems The gist of the present invention is to provide a method for preventing meandering of a steel strip using a straightening roll, wherein the tension of the steel strip in front of the straightening roll is detected, and the tension is measured as the amount of elongation of the steel strip. And calculating the sum of the thread winding angle with respect to the straightening roll from the amount of elongation, and adjusting the axis of the straightening roll to be perpendicular to the inclination of the steel strip by the calculated thread winding angle. This is a meandering prevention method for steel strip.

That is, the present invention detects the tension in front of the meandering straightening roll, obtains the sum of the thread winding angles from the result, adjusts the straightening roll so that the straightening roll is at a right angle to the thread winding angle, and sets the steel strip. This is to prevent the steel strip from meandering when the position where the tension is detected is moved to the position of the straightening roll.

Next, the meandering of the steel strip 1 will be described with reference to FIG. 1. If the elongation of the steel strip 1 takes any position in the width direction as shown by a dashed line, if the elongation is uniform, the steel strip 1 is incident on the roll 2 at a right angle. No meandering occurs. However, when the elongation amount 3 is not uniform as shown by the solid line, the incident angle θ between the roll 2 and the steel strip 1 is not a right angle, but meanders in the direction of the arrow due to the thread winding effect as shown in the figure. FIGS. 2 (a) and 2 (b) also show examples in which the elongation 3 of the steel strip 1 is uneven in the width direction, and the pattern of the elongation 3 is various. Meander in the direction of the arrow.

Therefore, in order to prevent the meandering, the roll in contact with the steel strip may be formed at a right angle. Nevertheless, it is difficult to manufacture only flat steel strip shapes, and poorly shaped ones convert the detection of the detected tension into the amount of elongation because the tension is uneven in the width direction. The roll is at right angles to the thread winding angle to prevent meandering.

When converting the detected value of tension to the amount of elongation, use the following (1) This is performed using an equation.

ε = strain difference between each sensor position σ = tensile stress at each sensor position, E = longitudinal modulus.

After the amount of elongation is obtained in this manner, the sum of the thread winding angles is calculated from the amount of elongation using equation (2).

P = distance between sensors, l = measured width length, c = characteristic coefficient (specific coefficient of equipment, etc.) When the sum of the thread winding angles is obtained in this way, the axis of the straightening roll is perpendicular to the sum of the thread winding angles. Adjust so that

The present invention will be described with reference to FIG. 3. FIG. 3 shows a part of the continuous annealing equipment, and the No. 2 bridle roll 4
And a No. 3 bridle roll 5 and a tension distribution detecting roll 6 for detecting the width distribution of the elongation of the steel strip 1 is provided.
Detect tension. Next, the sum of the thread winding angles is obtained using the above-described equations (1) and (2), and the steering roll 7 is adjusted so as to be perpendicular to the angle. Therefore, when the point A moves and the point B moves to the position B, the steering roll 7 is turned at right angles to the line winding angle obtained at the point A. It adjusts so that meandering does not occur.

Next, a block diagram for calculating the thread winding angle from the signal of the tension detecting roll 6 will be described with reference to FIG.

The tension detecting roll 6 detects the unit tension σ of the steel strip, and in order to calculate the elongation of the steel strip from the detected tension σ, an elongation calculator 8 is provided. Then, the thread winding angle calculator 9 calculates the sum of the thread winding angles using the equation (2).

That is, the present invention is characterized by taking the idea of the winding angle into the meandering prevention to prevent the meandering,
Although the theory that there is a correlation between the winding angle and the meandering prevention is not clear, FIG. 5 shows the test results.

The present inventors have conducted various tests and obtained the knowledge of the present invention from the test results. In FIG. 5, the vertical axis indicates the angle of the steering roll for preventing meandering, and the horizontal axis indicates the thread winding. Although it shows the sum of angles, there is a positive correlation as shown in the figure, and it is clear that the present invention is effective.

[Example] Next, an example of the present invention will be described.

The steel strip was passed through the continuous annealing equipment shown in FIG. 3 at a thickness of 0.30 mm, a sheet width of 885 mm, and a line speed of 390 m / min. Table 1 shows the results of detecting the tension at 11 points in the width direction of the steel strip with the tension detecting roll, calculating the thread winding angle, and preventing meandering.

The meandering amount of the steel strip was measured by a steel strip position detector 10 installed behind the steering roll in FIG. According to Table 1, a stable threading with less meandering than the conventional one is possible.

[Effects of the Invention] According to the present invention, a factor (uneven distribution in the width direction of elongation) that a steel strip tends to meander is detected in advance, and the factor is adjusted by adjusting the angle of a straightening roll. It is possible to prevent the running, and it is possible to stably pass the steel strip without generating a flaw in the steel strip, and the effect is extremely large.

[Brief description of the drawings]

1 and 2 are explanatory diagrams illustrating the principle of meandering of a steel strip, FIG. 3 is an explanatory diagram illustrating an example of an apparatus for implementing the present invention, and FIG. 4 is a diagram based on a signal of a tension detecting roll 6 of the present invention. FIG. 5 is a diagram showing a block diagram for calculating a thread winding angle, and FIG. 5 is a diagram showing the relationship between the thread winding angle and the angle of a steering roll according to the present invention. 1: steel strip, 2: roll, 3: elongation, 4: bridle roll, 5:
Bride roll, 6: tension detection roll, 7: steering roll, 8: elongation calculator, 9: thread winding angle calculator.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-58911 (JP, A) JP-A-53-108860 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C21D 9/52, 9/56, 11/00 B21B 37/00

Claims (1)

(57) [Claims] In a method for preventing meandering of a steel strip using a straightening roll, a tension of a steel strip in front of the straightening roll is detected, and the tension is converted into an elongation of the steel strip. A meandering prevention method for a steel strip, comprising calculating a sum of thread winding angles with respect to a roll, and adjusting the axis of the straightening roll to be perpendicular to the inclination of the steel strip by the calculated thread winding angle.