JPH0985321A - Shape control in mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent partial wear in the width direction of upper and lower auxiliary rolls even in the case of performing a large amount of rolling under the same rolling condition by always moving the absolute position in the axial direction of upper and lower auxiliary rolls at a low velocity by the same amount in the same direction during the rotation of rolls. SOLUTION: In a four-stage vertical type CVC mill, the roll clearance distribution between upper and lower rolls 12 in the roll axial direction is not entirely varied even though upper and lower rolls 16 are moved by the same amount in the same direction as the roll axis, accordingly the crown control effect also is not varied. Therefore, partial wear in the width direction of upper and lower rolls 16 is prevented by always moving upper and lower auxiliary rolls 16 at a low velocity by the same amount in the same direction as the roll axial direction. This roll oscillation is performed over the range of all strokes wherein rolls can be moved, moreover movement to the inverse side stroke is repeated changing the direction to the inverse direction in the case of reaching the stroke end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the shape of a rolling mill in a steel sheet rolling process for performing hot rolling or cold rolling, and more particularly to a relative roll axial direction between upper and lower auxiliary rolls provided with initial crowns. Suitable for use in a CVC (Continuously Variable Crown) mill that moves the positions relative to each other in opposite directions to continuously change the roll gap distribution between the upper and lower rolls along the roll axial direction, The present invention relates to a shape control method for a rolling mill capable of preventing uneven wear of rolls and improving product quality.

[0002]

2. Description of the Related Art In recent years, quality requirements for rolled steel sheets have become more and more strict, and demands for stricter strip shape after rolling have also increased. In order to deal with this, rolling mills having high shape control ability such as the CVC mill, pair cross mill, and HC 6-high mill have been developed (see Sumitomo Metals Technical Report Vol. 42-4 (1990) pages 190-200). .

Among these rolling mills having high shape control ability, the CVC mill is, for example, a 4-high vertical rolling mill as shown in FIG. 1 or a 6-high vertical rolling mill as shown in FIG. ,
Upper and lower auxiliary rolls (reinforcing roll 16 in FIG. 1, intermediate roll 14 in FIG. 2) are provided with initial crowns of the same shape, for example, as shown in FIG. The auxiliary rolls are relatively moved in opposite directions in the roll axial direction by the same amount, and the roll gap distribution between the upper and lower work rolls 12 along the roll axial direction is continuously changed. Is a rolling mill that controls the plate shape of the rolled material 10, and a large number of actual rolling mills are realized due to its high shape control capability.

For example, in Japanese Examined Patent Publication No. 63-62283, the upper and lower work rolls are provided with initial crowns having substantially the same shape so as to be point-symmetric with respect to each other, and these upper and lower work rolls are moved symmetrically in the axial direction so that the roll gap is pointed. It has been proposed that the structure be changed symmetrically, and that the crown and flatness of the rolling mill be easily controlled over a large range with a small number of rolls.

[0005]

The feature of the shape control in this CVC mill is that the upper and lower auxiliary rolls provided with the initial crowns of the same shape so as to be point-symmetrical are relatively moved in the roll axial direction to roll in the width direction. This is because the gap distribution is changed, and under the same rolling conditions (same deformation resistance, same strip width, same strip thickness), the relative movement amount of the upper and lower auxiliary rolls will always be the same value. The axial positional relationship of is always the same. In other words, under the same rolling condition, the portions where the rolled material contacts (interferes with) the upper and lower auxiliary rolls via the upper and lower work rolls are the same. Therefore, there is a problem that the upper and lower auxiliary rolls are unevenly worn in the width direction with respect to the initial crown.

Due to this uneven wear, the roll gap distribution due to the relative movement of the rolls is different from that at the time of the initial crown, which becomes an obstacle factor when the shape control is carried out.
At present, it is necessary to shorten the replacement cycle of the upper and lower auxiliary rolls, which is a big problem in terms of production efficiency and roll unit.

It is proposed in Japanese Patent Laid-Open No. 5-21643 that the second intermediate roll of the cluster rolling mill is continuously reciprocated in the axial direction in the same manner as in the present invention to roll the rolled material. However, it is described that the second intermediate roll moves upside down, and the axial movement of the first intermediate roll may be in the same direction or in the opposite direction.
It could not be directly applied to a C mill.

The present invention has been made to solve the above-mentioned conventional problems, and is capable of preventing uneven wear in the width direction of the upper and lower auxiliary rolls even when a large amount of rolling is performed under the same rolling conditions. The purpose is to do.

[0009]

SUMMARY OF THE INVENTION According to the present invention, the relative positions in the roll axis direction of the upper and lower auxiliary rolls having the same shape of the initial crowns provided so as to be point-symmetrical to each other are relatively moved in the opposite directions by the same amount. Then, by continuously changing the roll gap distribution between the upper and lower rolls along the roll axial direction, in the shape control method of the rolling mill for controlling the plate shape of the rolling mill, at the time of roll rotation, the upper and lower rolls are always The above-described object is achieved by moving the absolute position of the auxiliary roll in the roll axis direction by the same amount in the same direction at a low speed.

According to the present invention, in the rolling mill as described above, even if the upper and lower auxiliary rolls are moved in the same direction by the same amount in the roll axial direction, the roll gap distribution between the upper and lower rolls along the roll axial direction is It was made paying attention to the fact that it does not change at all.

That is, for the purpose of controlling the shape of the rolled material, the upper and lower auxiliary rolls provided with initial crowns of the same shape so as to be point-symmetrical to each other are relatively moved in the roll axial direction, and at the time of roll rotation, at all times, By moving the upper and lower auxiliary rolls in the same direction in the roll axial direction by the same amount at low speed, uneven wear in the width direction of the upper and lower auxiliary rolls is prevented.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Initial crowns applied to upper and lower auxiliary rolls (reinforcing roll 16 in the 4-high vertical rolling mill shown in FIG. 1 and intermediate roll 14 in the 6-high vertical rolling mill shown in FIG. 2) The embodiment of the present invention will be described in detail by taking the case where is a cubic curve as an example.

Now, assume that the initial crown is a cubic curve as shown in the following equation.

Y = −ax ³ + bx (1)

Then, as shown in FIG. 4, the crown y1 of the upper roll when the upper and lower auxiliary rolls are relatively moved in the opposite direction in the roll axial direction by .delta.1 is represented by the following equation.

Y1 = -a (x-δ1) ³ + b (x-δ1) (2)

Similarly, the crown y2 of the lower roll when it is moved relative to the roll axial direction by δ1 is expressed by the following equation.

Y2 = -a (x + δ1) ³ + b (x + δ1) (3)

Therefore, the upper and lower roll gap distribution Δy when relatively moved by δ1 in the direction opposite to the roll axis direction is expressed by the following equation.

[0020] Δy = y1 -y2 = -a {( x-δ1) 3 - (x + δ1) 3} -2b · δ1 = 2δ1 · {a (3x 2 + δ1 2) -b} ... (4)

From this state, as shown in FIG.
The upper roll crown y1 'when moved in the same direction along the roll axis is represented by the following equation.

Y1 ′ = − a (x−δ1−δ2) ³ + b (X−δ1−δ2) (5)

Similarly, the lower roll crown y2 'when moved by .delta.2 in the same direction along the roll axis is expressed by the following equation.

Y2 ′ = − a (x + δ1−δ2) ³ + b (x + δ1−δ2) (6)

Therefore, the upper and lower roll gap distribution Δy 'when moved by δ2 in the same direction along the roll axis is expressed by the following equation.

Δy ′ = y1′−y2 ′ = 2δ1 {a (3x ² + δ1 ² ) −b} (7)

The expression (7) is the same as the expression (4), and even if the upper and lower auxiliary rolls are moved by the same amount in the same roll axial direction, the roll gap distribution between the upper and lower rolls along the roll axial direction is It can be seen that it does not change at all and therefore the crown control effect does not change.

Therefore, the upper and lower auxiliary rolls are moved in the same direction in the roll axial direction by the same amount at a low speed all the time when the roll is rotated (hereinafter, referred to as roll oscillation), whereby the upper and lower auxiliary rolls are biased in the width direction. Wear can be prevented.

This roll oscillation can be carried out over the entire stroke in which the roll can be moved.
When the stroke end is reached, the direction can be changed in the opposite direction to move to the opposite stroke end, which can be repeated.

Since the purpose of preventing uneven wear in the width direction of the upper and lower auxiliary rolls is, the speed of roll oscillation is
The purpose can be sufficiently achieved at a low speed, and for example, about 1 cycle for 10 minutes is sufficient.

[0031]

As described above, according to the present invention,
Even if a large amount of rolling under the same rolling conditions is performed, it becomes possible to prevent uneven wear in the width direction of the upper and lower auxiliary rolls, reduce the frequency of replacement of the upper and lower auxiliary rolls, and improve the production efficiency. It is possible to reduce the basic unit. Furthermore, since the change from the initial crown is reduced, the quality of the plate shape is also improved.

[Brief description of drawings]

FIG. 1 is a front view showing a roll configuration of a 4-stage vertical CVC mill to which the present invention is applied.

FIG. 2 is a front view showing a roll configuration of a 6-stage vertical CVC mill.

FIG. 3 is a front view showing an example of an auxiliary roll provided with an initial crown, which is used in a CVC mill.

FIG. 4 is a diagram showing an example of a roll gap distribution when the upper and lower auxiliary rolls are relatively moved in the opposite direction of the roll axial direction by the same amount, for explaining the operation of the present invention.

FIG. 5 is a diagram showing an example of roll gap distribution when the upper and lower auxiliary rolls are moved in the same direction in the roll axial direction by the same amount.

[Explanation of symbols]

 10 ... Rolled material 12 ... Work roll 14 ... Intermediate roll 16 ... Reinforcing roll

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B21B 37/00 BBK 8315-4E B21B 37/00 BBK

Claims (1)

[Claims] 1. The relative positions in the roll axis direction of the upper and lower auxiliary rolls provided with the same shape of the initial crown so as to be point-symmetrical to each other are relatively moved in opposite directions by the same amount, and along the roll axis direction. In the shape control method of the rolling mill, which controls the plate shape of the rolling mill by continuously changing the roll gap distribution between the upper and lower rolls, during roll rotation, the roll axial direction of the upper and lower auxiliary rolls is always A shape control method for a rolling mill, characterized in that the absolute position is moved in the same direction by the same amount at a low speed.