JPH0312970B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a tension leveler for correcting shape defects such as partial elongation and warpage that occur during rolling of cold-rolled steel sheets, stainless steel sheets, aluminum sheets, etc. It concerns driving methods.

(Prior art) When a conventional tension leveler is operated and parts of the strip that do not require leveling (for example, welded parts of the strip, cracked edges, etc.) pass through the tension leveler, this is done to prevent the strip from breaking due to high tension leveling. (A) Before the leveling unnecessary part passes through the leveler, the strip tension is switched from high tension to low tension, and the leveler roll that is compressing the strip at the optimum interface is simultaneously opened quickly to achieve low tension and interface. An operating method in which a part that does not require leveling is passed through the leveler with the mesh open or in a zero state, and after passing, the leveler roll is simultaneously quickly closed and the strip tension is switched from low tension to high tension, or
(B) The leveler roll that is rolling down the strip is kept rolling down at the optimum intermesh, and before the part that does not require leveling passes through the leveler, the strip tension is switched from high tension to low tension, and the strip tension is changed to low tension and under the optimum intermesh. An operating method has been adopted in which the part that does not require leveling is passed through the leveler, and after passing, the tension is switched from low to high. However, when correcting the shape of a strip using a tension leveler, the flatness and warpage cannot be improved unless the strip is passed through all stages of leveler rolls set at the optimum intermesh under high tension.

In other words, as shown in Fig. 1, the flatness and warping history of the strip inside the leveler at a given moment change between each leveler roll, so in the operation method (A), the part that does not require leveling is removed before the strip passes through the leveler. When the tension switches from high tension to low tension, (i
-1) The strip that has been leveled with high tension by the first leveler roll is leveled with low tension by the i-th to n-th leveler rolls, and the shape is not sufficiently corrected by such partial leveling.

Furthermore, even when the leveler rolls are quickly opened at the same time, the flatness and warp history between the leveler rolls are different, making the shape unstable. Conversely, when the leveler roll is quickly closed at the same time after the leveling unnecessary part passes through the leveler and the strip tension is switched from low tension to high tension, the i-th strip will be leveled by the subsequent leveler rolls from the first one. (i-1) Since the roll is not rolled down by the leveler roll up to the first one, the shape becomes unstable.

Also, in case (B) above, when the strip tension switches between high and low tension, the shape becomes unstable due to the above-mentioned reasons, and since leveling is performed with the leveler roll being pressed down at low tension, the shape becomes unstable. The part is longer than that in (A), which is not preferable.

The conventional operating methods (A) and (B) and the shape of the strip (flat and warped) are shown in FIGS. 2a and 2b.

In addition, the strip tension shown here is defined as high tension when the yield stress of the strip to be straightened is YP (Kg/mm ² ) and the strip tension is σt (Kg/mm ² ). , σt<1/3YP is defined as low tension.

(Problems to be Solved by the Invention) The present invention solves the conventional problems, and eliminates the need for leveling in the strip by breaking it in the leveler, and furthermore, the strip before and after the needless leveling part has excellent flatness, and is particularly free from warping. The present invention provides a method of operating a tension leveler that produces a good strip with less friction.

(Means for Solving the Problems) When the shape of a strip is corrected through a tension leveler, the present invention applies all the rolls of a plurality of leveler rolls in which the strip is rolled down at an optimum interval under a constant high tension. A good shape can only be obtained after threading, and if the strip tension changes while being rolled down with a leveler roll, or if the strip is partially rolled down with a leveler roll, the shape will be poor and it is not desirable. This is based on the premise that.

In particular, when the welded part of the strip passes through a tension leveler, the strip before and after the welded part may be partially rolled down by the leveler roll or the strip tension may be low, resulting in poor shape. Conventionally, there was no method for correcting this defective portion, and the present invention solves this problem.

That is, in the present invention, the correction conditions of the tension leveler are made appropriate according to the movement of the strip so that the uneven portions such as warpage do not occur when the portion of the strip that does not require leveling passes through the leveler.

The present invention will now be explained in detail using FIG. When the part of the strip that does not need leveling reaches a predetermined position in front of the tension leveler (for example, the frontmost roll of the bridle roll on the entrance side of the tension leveler), the intermeshing of the first leveler roll counting from the entrance of the leveler is is zero or reduced, and then when the strip moves downstream and the opening start point (point A in Figure 3) by leveler roll #1 reaches directly below leveler roll #2, the intermesh of leveler roll #2 is opened. Alternatively, it is zeroed or reduced, and then when point A reaches leveler roll #3 due to downstream movement of the strip, the intermesh of leveler roll #3 is released, zeroed or reduced.

Here, the intermeshing of the leveler roll is explained using Fig. 7. State (i) shows the optimal intermeshing, (ii) shows the state where the intermeshing is reduced, and (iii) shows the intermeshing. The thread zero (iv) indicates that the interface is open.

Furthermore, by performing this method toward the final leveler roll that is being rolled down, the downstream side of the strip from the opening start point of the first leveler roll will be rolled down at the optimum intermesh of all leveler rolls, and from the opening start point. The upstream side of the strip has all leveler roll interfaces open, zero, or reduced.

Next, after point A reaches final leveler roll #n,
After the intermesh of leveler roll #n has been opened, zeroed or reduced, the strip tension is switched from high tension to low tension. In addition, points A and B in Figure 3 are about 2 points from the leveling unnecessary part.
It shows a point about ~5m away.

In this way, in the leveling-free portion, the intermesh of the leveler roll is opened, zeroed, or reduced, and the strip tension is reduced to a low one, allowing the strip to pass through the leveler. On the other hand, when the part that does not require leveling reaches a predetermined position after passing through the leveler (for example, the rearmost roll of the bridle roll on the exit side of the tension leveler), the procedure is reversed to that described above, i.e.,
After switching the strip tension from low tension to high tension, the first leveler roll at the leveler inlet is rolled down at the optimum interval, and after rolling down, the strip is moved downstream to the rolling start point (third When point B in the figure reaches just below leveler roll #2, leveler roll #2 is rolled down at the optimum interval. By carrying out this method up to the final leveler roll #n, all the leveler rolls are rolled under high strip tension on the upstream side of the strip from point B.

However, if the strip to be straightened is made of a soft material or has a thick plate, touch marks of the leveler roll are likely to be attached to the strip when the leveler roll is rolled down under high tension, which is undesirable. These touch marks indicate the amount of reduction of the leveler roll: IM (mm), the span length between the leveler roll and the deflector roll: L (mm), the diameter of the leveler roll: D (mm), the thickness of the strip: t (mm), If the yield stress of the strip is YP (Kg/mm ² ) and the strip tension σt (Kg/mm ² ), then logIM/L≧−5.4−1.7logt・σt/D・YP … occurs under the conditions that satisfy (1) This was experimentally confirmed.

Therefore, when formula (1) is satisfied, in order to prevent the occurrence of touch marks, the leveler roll is first lowered when the unnecessary leveling part passes through the leveler and reaches a predetermined position, and then the strip tension is lowered. After switching from tension to high tension, the rolling start point B moves downstream and lowers the leveler rolls to the final stage (#n), so that from point B on the upstream side of the strip, all the leveler rolls are applied under strip high tension. Moreover, the generation of touch marks can also be prevented as shown in FIG. 6, making it more effective.

As described above, the present invention is capable of improving the shape (especially warpage) over the entire length of the strip without breaking the portion that does not require leveling in the operating method when passing through the portion of the strip that does not require leveling.

In addition to the method described above, the method for opening and rolling down the leveler rolls is similar to that for opening and rolling down the intermesh for every number of leveler rolls, dividing the group into the leveler roll group on the entry side and the leveler roll group on the exit side. Effects can be obtained. Furthermore, among the leveler rolls #1 to #n, those rolls that have little effect on changes in warp of the strip can be omitted from the operations of opening and rolling down the intermesh.

Next, an example of an apparatus for implementing the present invention will be explained with reference to FIG. A group of leveler rolls 2 provided for leveling the strip 1, an inlet bridle roll 3, an outlet bridle roll 4, a pulse counter 5 for tracking the strip, and a lowering for lowering and opening the leveler rolls 6, 7, and 8. Setting devices 10, 11, 12, and 13 and a load cell 14 for measuring tension in the leveler are installed. The strip tracking pulse counter signal is used to track and calculate the position of the unnecessary part in the strip, and the tension control device 15 which controls the tension in the strip according to the downstream movement of the strip and the intermesh of each leveler roll are operated. The operating method of the present invention can be implemented by installing the arithmetic device 16 to be set.

FIG. 5 shows the line speed, strip tension in the leveler, leveler roll, warpage, flatness, etc. when the present invention was carried out, and it can be seen that the shape is good.

(Effects of the Invention) As described above, with the tension leveler threading method of the present invention for the part of the strip that does not require leveling, the change in warpage at the end and start of leveling of the strip before and after the part that does not require leveling can be prevented without breaking the part that does not require leveling. can be prevented,
It is extremely advantageous because it can improve yield and production capacity.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing changes in the shape (curvature, flatness) of the strip in the leveler according to the conventional method, Fig. 2 a and b are explanatory diagrams showing the conventional operating method, and Fig. 3
The figure is an explanatory view showing the method of passing a strip through a tension leveler according to the present invention, Fig. 4 is a block diagram showing an example of an apparatus of the present invention, and Fig. 5 is an explanatory view showing the shape when the method of the present invention is carried out. , FIG. 6 is an explanatory diagram showing the experimental results of the occurrence of roll touch marks, and FIG. 7 is an explanatory diagram showing the interface of the leveler roll.

Claims (1)

[Claims] 1. When correcting the shape of the part of the strip that does not require leveling using a tension leveler, before the part that does not require leveling passes through the leveler, the leveler roll that is compressing the strip at an arbitrary intermesh is moved to move the strip. While moving from the leveler roll on the entry side of the leveler to the leveler roll on the exit side, after the leveler roll intermesh is opened, zeroed, or reduced, the tension acting on the strip is reduced from high tension to low tension. After passing through the leveler, switch the strip tension from low to high, and then move the strip from the leveler roll on the input side to the final leveler roll on the output side. A method of operating a tension leveler, characterized in that a leveler roll is rolled down to a strip at an arbitrary interval. 2. When correcting the shape of the part of the strip that does not require leveling using a tension leveler, before the part that does not require leveling passes through the leveler, move the leveler roll that is pressing down the strip at an arbitrary intermesh to the side where the leveler enters while moving the strip. After the intermesh of the leveler roll is opened, zeroed, or reduced as it moves from the leveler roll to the leveler roll on the output side, the tension acting on the strip is switched from high tension to low tension, and the leveling unnecessary part is removed. After passing through the leveler without breaking the strip, move the strip from the leveler roll on the entry side to the final leveler roll on the exit side, press down the leveler roll onto the strip at an arbitrary intermesh, and then A method of operating a tension leveler characterized by switching tension from low tension to high tension.