JPH0576915A - Method for setting roll gap of rolling mill - Google Patents

Abstract

PURPOSE:To prevent the generation of unevenness in thickness on the whole region of a sheet by opening roll gap before a rolled stock is bitten and after the end of the sheet is passed through and always setting roll gap in the normal position during rolling. CONSTITUTION:In a pair cross rolling mill which upside rolls and downside rolls which respectively consist of a pair of back-up rolls 4, 5 and work rolls 2, 3 are intersected in a plane parallel to a material 1 to be rolled, at the time of no sheet before biting, the upper and lower workrolls 2, 3 are opened at the preset value of roll gap and the value of roll gap is set at the normal value just before the sheet is bitten. Then, roll gap is opened just after the end of sheet is passed through.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll gap setting method for a rolling mill for rolling a sheet material by a pair cross rolling mill in which upper and lower rolls are crossed in pairs.

[0002]

2. Description of the Related Art As a means for improving the thickness accuracy of a rolled product in the plate width direction, an initial crown is attached to the roll in order to cancel the bending of the roll due to the rolling load. In this case, in order to cancel the bending of the roll due to the rolling load, the initial crown is attached to the roll, but if the rolling conditions such as plate width and thickness of the plate material change, it is necessary to replace it with a roll of another crown. Therefore, it is necessary to keep a roll having many kinds of initial crowns. In addition, the replacement of the roll causes a decrease in the operating rate of the rolling mill, and the roll wear and thermal expansion accompanying the progress of the rolling operation significantly change the roll crown.

In order to solve this problem, for example, Japanese Patent Laid-Open No.
As described in 5-64908, the upper work roll and the upper backup roll, and the lower work roll and the lower backup roll are held parallel to each other to form the upper pair roll and the lower paper roll, and the axes of the upper and lower pair rolls are in the horizontal plane. There is a technology to roll the plate material by crossing with.

However, when rolling is performed with the shaft centers of the upper and lower work rolls slightly inclined in the horizontal plane, a force (that is, thrust force) in a direction parallel to the roll shaft is generated, and a mechanism such as a bearing that supports this thrust force. However, depending on rolling conditions, the thrust receiving mechanism may be damaged, resulting in a serious facility accident (for example, bearing damage).

As a method for preventing the thrust force from becoming excessive, there is, for example, Japanese Patent Publication 1-24565. The thrust force becomes larger when the upper and lower rolls are rotated in a kissing state without a plate than during plate rolling, and this tendency is
In normal plate rolling, there are many cases where thin materials are rolled. Japanese Patent Publication No. 1-24655 focuses on this point,
In the idling state where the plate is not rolled, the roll opening is set so that the pressing force of the upper and lower rolls is zero (or becomes small enough), and after the biting of the plate, it is set to the predetermined roll opening. A technique is proposed in which the sheet material is changed and rolled, and before the sheet material comes off and becomes idle, the roll opening in the idle state is reset to zero (or sufficiently small) to perform rolling. ing.

[0006]

However, in the above-mentioned prior art, since the roll opening is changed after the plate material is engaged and before it is removed, the plate at the tip end and the tail end of the plate is changed. There is a problem that the thickness increases and the yield decreases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for setting a roll gap of a rolling mill, which has been made in view of the above-mentioned circumstances of the prior art, and in which the plate thickness mismatch does not occur in the entire area of the plate. ..

[0008]

In order to achieve the above object, the present invention provides an upper roll and a lower roll each consisting of one set of backup roll and work roll in a plane parallel to the material to be rolled. In a pair cross rolling machine that is relatively crossed with, the roll gaps of the upper and lower work rolls are opened in advance when there is no plate, the roll gap value is set to the normal value immediately before biting of the plate, and the roll gap is opened after slipping out. I am trying.

[0009]

According to the above-mentioned means, the roll gap is preliminarily opened before the plate is caught, and the roll gap is set to the normal value at the same time when the plate is caught. As a result, it is possible to prevent the thrust force from becoming excessive in the idling state and prevent the plate thickness variation at both ends of the plate after rolling. In addition, since the roll gap is opened immediately after slipping out, it is possible to prevent generation of excessive thrust force when slipping out.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flow chart showing a roll gap setting method for a rolling mill according to the present invention. 2 is a schematic overall configuration diagram of a rolling apparatus to which the present invention is applied, and FIGS. 3 and 4 are a plan view and a front view showing a detailed configuration of the rolling mill of FIG.

As shown in FIG. 2, a pair of upper work rolls 2 and lower work rolls 3 are arranged to cross each other so that the material 1 to be rolled can be sandwiched from above and below. With respect to a line orthogonal to the traveling direction of the material 1 to be rolled, each roll horizontally forms an angle θ.
It is arranged with. The upper work roll 2 is provided with an upper backup roll 4 parallel to the upper side thereof,
A lower backup roll 5 is arranged below the lower work roll 3 in parallel with the lower work roll 3.

In the figure, b is the width of the material to be rolled, D _w is the work roll diameter, θ is the roll crossing angle of 1/2, S _c is the roll interval at the plate center, and S _e is the plate edge. The roll intervals are shown. As is clear from FIGS. 3 and 4, the roll distance S _e at the plate edge portion becomes wider as the roll intersection angle becomes larger than the roll spacing S _c at the plate center portion, and the roll crown becomes larger as the roll intersection angle becomes larger. Will grow.

Further, as shown in FIG. 2, a sensor 6 and a sensor 7 are provided on the inlet side and the outlet side of the rolling mill having the above-mentioned structure, and the rolled material 1 approaches the position just before the rolling mill is caught. And the missing board is detected. The sensors 6 and 7 are installed, for example, at a position 3 m before and after the roll biting position.

FIG. 5 is a thrust force characteristic diagram. As shown by the solid line characteristics in the figure, the thrust force increases with the passage of time after the rolled material 1 is bitten, but after a certain period of time, it becomes saturated. The time to reach this saturated state is, for example, 10 seconds after the start of biting, and if rolling is performed at a regular rolling reduction value within this time, the rolling mill will not be burdened. The present invention focuses on this point, and bites the material 1 to be rolled before the saturation level is reached so that rolling can be performed with a small thrust force. In the figure, the characteristic of the broken line indicates the thrust force characteristic during rolling.

Next, the roll gap setting process and strip trailing process in the present invention will be described with reference to the rolling explanatory view of FIG. Here, the mill rigidity of the rolling mill is 800 tons / mm, and the zero adjustment of the roll gap when the rolls are rearranged is 2000 tons. Therefore, when the rolling reduction value is 2.5 mm or less, the upper and lower rolls are in a kissing state (the upper work roll 2 and the lower work roll 3 are in a pressure contact state). In the following, it is assumed that the material 1 to be rolled is finished by reverse rolling to have a thickness of 4.5 m (width) × 35 m (length) and a final thickness of 4.8 mm to 4.5 mm.

First, the roll gap setting will be described. First, it is determined whether or not the roll kiss is on standby (S1). If the roll kiss is on standby, the upper and lower rolls are opened and the opening is set to +0.5 mm (S2). Therefore, the upper work roll 2 and the lower work roll 3 are not in contact with each other. Waiting for the rolled material 1 to enter in this state, the tip of the rolled material 1 reaches just below the sensor 6, and when the sensor 6 generates a detection signal (S3), the roll gap is set to a normal value ( S4). This time point is the position B in FIG. The roll gap value S in this case is 2.0 mm
Is. In the case of the present embodiment, it takes 4.5 seconds from the sensor 6 to the biting position (C in FIG. 6), so that the setting of the reduction can be completed within this time. Since this time is not the time when the thrust force reaches the maximum, rolling can be performed with a regular roll gap without exceeding the allowable thrust load of the rolling mill, and as shown in the plate thickness characteristic diagram of FIG. A predetermined plate thickness (4.5 mm) can be obtained from the leading edge.

During rolling, the roll opening is set to -0.5 mm, and the rolling load becomes 4000 tons after biting. In addition, the thrust pressure sharply rises to 600 tons just before biting (in this case, since the mechanical strength of the rolling mill is 750 tons, there is no risk of damaging the equipment), but it drops to 150 tons at the same time as biting. ..

Next, the plate trailing edge removal processing will be described.

First, it is determined whether or not the roll kiss state is present (S6). The position D in FIG. 6 indicates the time of stripping,
The roll pressure contact load is reduced to 400 tons, but the thrust pressure rapidly rises to 600 tons again immediately after the plate is pulled out. After a few seconds, the tail end of the material 1 to be rolled reaches the position E, and the passage of the plate is detected by the sensor 7 (S7). Upon detection of this, the roll opening is again set to the + side (S8), and the rolling load and thrust pressure sharply decrease. As a result, it is possible to prevent the roll from becoming a kiss state after the completion of rolling, and it is possible to prevent the generation of an excessive thrust force. Further, the reduction value is set in preparation for the next entry of the material to be rolled (S9).

[0021]

As is apparent from the above, according to the present invention, an upper roll and a lower roll each consisting of a set of a backup roll and a work roll are relatively arranged in a plane parallel to the material to be rolled. In the crossed pair cross rolling mill, the roll gaps of the upper and lower work rolls are opened in advance when there is no plate, and the roll gap value is set to the normal value immediately before biting of the plate, so the thrust force in the idling state is excessive. It is possible to prevent the occurrence of a change in thickness and to prevent a change in plate thickness at both ends of the plate after rolling.

[Brief description of drawings]

FIG. 1 is a flowchart showing a roll gap setting method for a pair cross rolling mill according to the present invention.

FIG. 2 is a schematic overall configuration diagram of a rolling apparatus to which the present invention is applied.

FIG. 3 is a plan view showing a detailed configuration of the rolling mill of FIG.

FIG. 4 is a front view showing a detailed configuration of the rolling mill of FIG.

FIG. 5 is a thrust force characteristic diagram.

FIG. 6 is a rolling explanatory diagram showing roll opening, rolling load, thrust pressure and plate thickness value in the present invention.

[Explanation of symbols]

 1 rolled material 2 upper work roll 3 lower work roll 4 upper backup roll 5 lower backup roll 6 sensor 7 sensor

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Riki Michioka 1 Kimitsu, Kimitsu-shi, Chiba New Nippon Steel Co., Ltd. Kimitsu Steel Co., Ltd.

Claims (1)

[Claims] 1. A pair cross rolling machine in which an upper roll and a lower roll, each consisting of a set of a backup roll and a work roll, are relatively crossed in a plane parallel to the material to be rolled, and the upper and lower rolls without a plate. A roll gap setting method for a rolling mill, characterized in that the roll gap of the work roll is opened in advance, the roll gap value is set to a normal value immediately before biting of the plate, and the roll gap value is opened immediately after slipping out of the plate bottom. ..