JPH0732018A - Rolling mill and rolling method with small hysteresis - Google Patents

Abstract

PURPOSE:To highly precisely control a sheet thickness by providing a calculating function to predict a rolling reaction force of a sheet to be rolled, a function to calculate a suitable initial interval of cross head corresponding to this predicted rolling reaction force and a mechanism to regulate the initial interval of the cross head to hold chocks. CONSTITUTION:In a rolling mill having a cross head to hold working rolls and chocks of reinforcing rolls in the housing window of the rolling mill, a calculating function to predict a rolling reaction force of a sheet to be rolled, a function to calculate a suitable initial interval of the cross head corresponding to this predicted rolling reaction force, and a mechanism to regulate the initial interval of the cross head to hold the chocks are provided. Further, the hysteresis of an automatic sheet pressure controlling device (AGC) is always made small by setting into a suitable initial interval of the cross head corresponding to this predicted reaction force, the sheet thickness can be highly precisely controlled. Then, the hysteresis ton number is reduced, the error of the rolling reaction force detected value is made small, and the quality competitive power is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-precision rolling mill having a small hysteresis and a rolling method capable of rolling a plate material having a high plate thickness accuracy.

[0002]

2. Description of the Related Art The housing window width X ₀ of the conventional rolling mill shown in FIG. 4 is constant, and this window width holds the chocks of the reinforcing rolls and the work rolls. 1 to 1 for rolling mill
It is designed to be 1.5 mm.

If the clearance is large, it causes backlash of the rolling mill, and the linear rolling property of the material to be rolled deteriorates. When the clearance is reduced, the window width is narrowed as shown by the broken line by the reaction force of the material to be rolled as shown in FIG. 4, and the roll chock is sandwiched by a force of several tens of tons as shown in FIG. At this time, the friction between the chock and the housing window becomes large, the movement of the automatic plate thickness controller (AGC) becomes poor, and the plate thickness control accuracy deteriorates.

Further, as the friction between the chock and the housing window increases, the reaction force detection value for the rolling position (roll gap) increases as the roll gap increases and decreases as shown in FIG. If you do, it will be smaller. The reaction force detection error H with respect to such a rolling position (roll gap) is called a hysteresis variable.

The hysteresis ton number indicates the degree of poor vertical movement of the roll chock, and FIG. 6 shows the relationship between the change in clearance and the hysteresis ton number. When the window width becomes narrower and the clearance becomes negative, the number of hysteresis peaks increases, and along with this, the accuracy of AGC movement deteriorates.

[0006]

SUMMARY OF THE INVENTION The present invention prevents the generation of a large frictional force between the roll chock and the inner surface of the window due to a change in the clearance between the roll chock and the window due to the rolling reaction force, and highly precise plate thickness control. The purpose is to enable.

[0007]

Means and Actions for Solving the Problems The gist of the present invention is as follows. (1) In a rolling mill having a crosshead for holding chocks of work rolls and reinforcing rolls in a housing window of the rolling mill, a calculation function for predicting a rolling reaction force of a material to be rolled and corresponding to the predicted rolling reaction force A rolling mill having a small hysteresis, which is provided with a function of calculating an appropriate initial distance of the crosshead and a mechanism for adjusting the initial distance of the crosshead that holds a chock.

(2) When rolling with a rolling mill having a cross head for holding the chocks of the work rolls and the reinforcing rolls in the housing window of the rolling mill, the rolling reaction force is predicted from the rolling conditions of the material to be rolled. A rolling method with a small hysteresis, which is characterized by setting an appropriate crosshead initial gap corresponding to a predicted rolling reaction force.

The details of the present invention will be described below with reference to the drawings. As shown in FIG. 5, the window width changes due to the rolling reaction force. The clearance C between the inside of the window and the roll chock is expressed by the following equation. C = (X ₀ −ΔX) −W X ₀ ; initial window width (mm) ΔX; window width change due to rolling reaction force (mm) W; roll chock width Therefore, the window width change ΔX is predicted according to the rolling conditions, and the window is changed in advance. If the width X is set by the following equation, X = X ₀ + ΔX The clearance can be kept in an optimum state. However, the window width of the integral housing cannot be changed appropriately. Therefore, we adopted a mechanism in which the crosshead is placed inside the housing window and the roll chock is held inside the crosshead.

In this crosshead, a roll chock holding interval of the crosshead can be adjusted by rotating a reduction screw fixed to the housing by driving a motor and pushing and pulling the crosshead.

A pair cross mill widely used as a conventional crown control mill has the mechanism shown in FIGS. 1 and 2, and the cross head 1 holding the chock 2 is moved in the same direction on both sides to move the upper and lower rolls 7. Change the position of chock 2 (bearing box) and set the angle of the upper and lower rolls. In the present invention, the crosshead is moved in opposite directions on both sides of each material to be rolled to adjust the interval for holding the chocks, that is, the crosshead interval X. In the figure, 3 is a screw down screw, 4 is a drive motor, 5 is a housing, and 6 is a worm gear that is interlocked with the drive motor 4 via a bevel gear. By rotating the worm gear 6 with the motor 4, the screw 3 is rotated to adjust the position of the crosshead 1.

[0012]

Embodiment FIG. 3 shows a flow of control logic of the embodiment. The rolling reaction force is predicted from the rolling conditions, rolling speed, dimensional component temperature of the material to be rolled and other conditions, and the window width change is calculated from the rolling reaction force. Determine the optimum crosshead spacing and adjust the initial crosshead spacing. The optimum crosshead spacing is set so that the clearance between the roll chock and the inner surface of the crosshead remains zero or slightly. In this example, Table 1
The method of the present invention was adopted in the rolling mill shown in FIG.

[0013]

[Table 1]

[0014]

According to the present invention, in the hot rolling mill, by setting the initial crosshead interval according to the rolling conditions,
The hysteresis of GC was always small, and high-precision plate thickness control could be implemented. The hysteresis ton number H was 60 to 100 tonnes before the present invention was adopted, but in the example, it was 40 tonnes.
It decreased to 50 tons.

Therefore, the error in the rolling reaction force detection value of the automatic plate thickness controller (AGC) is reduced, and the rolling position (roll gap) adjustment accuracy is doubled. As a result, the product thickness accuracy of the product is a strip with a product thickness of 2.0 to 4.0 mm, the total thickness error is ± 80 μm
In the example of the present invention, it was reduced to ± 50 μm, and the quality competitiveness was greatly improved.

[Brief description of drawings]

FIG. 1 shows an outline of a crosshead interval adjusting mechanism.

FIG. 2 is a sectional view showing a relationship between a housing, a crosshead and a roll chock.

FIG. 3 shows a flow of control logic of the embodiment.

FIG. 4 shows a housing window, in which the deformation when a rolling reaction force is applied is indicated by a broken line.

FIG. 5 shows the relationship between rolling reaction force and the amount of change in the housing window width.

FIG. 6 shows the relationship between the clearance between the roll chock and the inner surface of the window and the number of AGC hysteresis tones.

FIG. 7 shows an explanation of the hysteresis number.

[Explanation of symbols]

 1 Crosshead 2 Roll chock 3 Reduction screw 4 Drive motor and clutch 5 Housing 6 Worm gear that transmits rotation to the reduction screw 7 Roll

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B21B 31/02 C 8727-4E

Claims (2)

[Claims] 1. A rolling mill having a cross head for holding chocks of work rolls and reinforcing rolls in a housing window of the rolling mill, and a calculation function for predicting a rolling reaction force of a material to be rolled and a predicted rolling reaction force for the rolling reaction force. A rolling mill having a small hysteresis, which is provided with a function of calculating a corresponding appropriate initial crosshead interval and a mechanism for adjusting the initial crosshead interval for holding a chock. 2. When rolling with a rolling mill having a cross head for holding chocks of work rolls and reinforcing rolls in the housing window of the rolling mill, the rolling reaction force is predicted from the rolling conditions of the material to be rolled, and this prediction is made. A rolling method with small hysteresis, which is characterized by setting an appropriate initial distance of the crosshead corresponding to the rolling reaction force.