JP3474124B2 - Rolling method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rolling method,
In particular, in the plate crown control of the rolling mill, when the cross angle is small, the cross angle is controlled to 0 degree without giving the cross angle,
It relates to a new improvement for obtaining a reduction in thrust force.

[0002]

2. Description of the Related Art In recent years, the demands on the plate crown of hot-rolled steel sheets tend to be diverse and severe. A crown is required, and for a material for cold rolling and plating, a plate crown having a certain size is required in order to secure plateability during cold rolling and prevent excessive adhesion of plating on the edge portion. In order to meet the requirement of the plate crown, the tandem rolling mill is usually constituted by a continuous rolling mill consisting of four-high rolling mills. It is performed by a roll bending device of a rolling mill. However, since than those only that there is a limit to control the strip crown and shape, then rolling mill has been developed incorporating a variety of high-performance features. For example, there is a tandem rolling mill that has a roll movable in the axial direction and incorporates a rolling mill that controls the plate crown shape by using the roll operation and working roll bending together. Control became possible. Further, Japanese Patent Publication No. 59-41804 discloses a cross rolling machine for controlling a plate crown or the like by crossing work rolls in a horizontal plane.

Further, in Japanese Patent Laid-Open No. 55-153605, there is a 4
A multi-stage rolling mill has been proposed in which the upper roll and the lower roll are made to cross each other at a required angle with respect to a line perpendicular to the rolling direction in a plane including the rolling direction. From the interrelationship between the cross angle and the gap between the upper and lower rolls, increasing the cross angle can reduce the plate crown, and conversely, reducing the cross angle can increase the plate crown. The desired plate crown in the material is obtained.

Further, in a four-high rolling mill, when only the work rolls are crossed, an excessive thrust force of 30% of the rolling load is generated between the backup roll and the work rolls. Although a device was required, a single cross rolling mill that supplies a lubricant between the backup roll and the work roll to reduce the thrust force has been developed and is in operation.

[0005]

The directions of the roll peripheral speed and the thrust force when only the work rolls are crossed in the above-described four-high rolling mill are as shown in FIGS. 6 and 7.
Work rolls WR1 and WR2 and backup roll BU
At the contact portion of R1 and BUR2, since the peripheral speeds of the work roll and the backup roll are different from each other, relative slip between the rolls occurs in the axial direction, and the frictional force acting in the axial direction at this time is called the thrust force. ing. Since this thrust force reaches 30% of the rolling load without lubrication, in order to reduce the thrust force, lubricating oil is supplied between the work rolls and the backup rolls to reduce the friction coefficient during relative sliding between the rolls.

In this case, the relationship between the angle at which the work rolls WR1 and WR2 are crossed and the thrust coefficient between the work rolls WR1 and WR2 and the backup rolls BUR1 and BUR2 is shown in FIG. In the minute cross angle region up to 1 degree, the thrust coefficient increases in proportion to the increase of the cross angle. Next, the relationship between the cross angle of the work roll and the plate crown on the exit side of the cross mill stand is shown in FIG. 9. The reduction ratio of the mill is 40% and the plate thickness is 6 mm with low carbon steel. Board width 1230
If the cross angle is about 0.3 degree, the plate crown at the time of rolling the plate having a thickness of 0.3 mm has little improvement effect on the plate crown, but it is an indispensable condition when applying the cross angle and rolling. It had to be done while supplying the lubricating oil.

When the plate crown is controlled, the work roll cross angle control, which has a large controllability, is prioritized. However, in the range where the cross angle is small, the thrust force is avoided although the plate crown control effect is small. It was necessary to constantly supply the lubricating oil for.

The present invention has been made in order to solve the above problems, and particularly when the cross angle may be small, the crossing angle is set to 0 degree and the bending force is controlled with priority to control the bending force. It is an object of the present invention to provide a rolling method in which, when it exceeds, crown control is performed by using only work roll cross angle control or bending control and work roll cross angle control in combination.

[0009]

Means for Solving the Problems] rolling method according to the present invention, have at least work rolls and backup rolls
And work roll cloth for plate crown control
Thing with angle control function and bending control function
In the rolling method of Rukurosu mill phases bending force in the bending controllable range of the work rolls
When the applicable cross angle limit value is exceeded (4th step
103) , using the bending control and the work roll cross angle control together, and less than the cross angle limited value
In the case of (5th step 104), the bending control is performed.
A rolling method for performing plate crown control similar. Also, the case cross angle limit value of the work rolls is less than 0.3, a method der performing the cross angle is set to 0 degrees the <br/> bending control only in strip crown control of the work roll
It

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a rolling method according to the present invention will be described below with reference to the drawings. That is, as shown in Figure 2, when the cross angle of the work roll WR1, WR2 in crossing mill stand 2 of continuous hot rolling mill 1 is Ru der than 0.3 degrees, the cross angle 0 ° When the bending force exceeds the control capability range, the work roll cross angle control alone or the bending control and work roll cross angle control are used together to control the plate crown. To do.

Next, the setup of the rolling mill will be described with reference to the control flow shown in FIG. As the first step 100, for example, 47.5 (ton / chock) is temporarily set as the bending force. After completing this temporary setting, the second step 1
In 01, the output side plate crown ratio of the cross mill rolling mill is set to be the finishing final stand output side plate crown ratio. That is, a well-known linear or rotary type
Operate the actuator by a controller (not shown)
Set the cross angle of each work roll WR1 and WR2
I can. The above set of operations is well known,
For example, JP-A-55-153605, JP-A-5-
Japanese Patent No. 50110, Japanese Patent No. 2709777, and Japanese Patent No. 2709777
It is disclosed in Japanese Patent No. 2743126. In the third step 102, the work roll cross angle of the rolling stand is calculated. In a fourth step 103, the cross angle obtained in the third step 102 is to determine whether is within 1.2 degrees from the cross angle limit setting value 0.3 degrees. If it is within the limit setting range, the bending force is a preset value, and the cross angle and the bending force cooperate to perform plate crown control. Next, if the cross angle is less than 0.3 degree in the fifth step 104, the cross angle limit value is set to 0 degree in the fifth step 104. After the cross angle is set to 0 degree, the bending force is recalculated in the sixth step 105. In the seventh step 106, the bending force is within the limit range of 15 (ton / chock)-
Determine if it is 80 (tons / chock). In the eighth step 107, the bending force limit range in the seventh step 106 is 15 (ton / chock) to 80 (ton / choc).
If you are out of the chocks) 15 also (ton / chock)
Is set to 80 (tons / chock).

[0012]

EXAMPLES Next, the present invention is applied to a cross mill (single cross mill) of one finishing third stand F3 of the continuous hot rolling mill 1 of FIG. 2 having the finishing mill stands F1 to F7. did. Cross angle of the work roll WR1, WR2 is configured to impart a cross angle of 0 to 1.2 degrees. The work rolls WR1 and WR2 were set so as not to cross until the cross angle was less than 0.3 degrees, and the plate crown was controlled only by the bending force. The control characteristics are shown in FIG. Rolled material thickness of low carbon steel 6mm at this time, the rolled material in the plate width 1230Mm, the rolling reduction of the stand was 40%, bending strength at the stand
When the operating range of (tons / chock) is changed from 15 to 80 (tons / chock), the plate crown on the stand-out side of the stand is 310 to 350 μm and approximately 4 as shown in FIG.
The improvement effect of 0 μm can be given, and the conventional method is shown in FIG.
It was possible to achieve plate crown control equivalent to or better than the cross angle priority control shown in.

The rolling application rate to which the control giving priority to the cross angle is applied is shown in FIG. 4. Conventionally, 68% was applied for rolling, but when the cross angle is less than 0.3 degrees, work rolls are used. If only the bending force is applied without controlling the cross angle, the cross angle application rate is reduced by about 44% and 24%. As a result, the backup rolls BUR1 and BUR2
The amount of lubricating oil supplied between the work rolls WR1 and WR2 was significantly reduced.

[0014]

Since the rolling method according to the present invention is configured as described above, the following effects can be obtained. That is, when the plate crown control is performed, only the bending control is performed by setting the work roll cross angle priority control to the cross angle of less than 0.3 degrees without giving the cross angle to 0 degree, so that the thrust force (see FIG. Does not work, and it becomes unnecessary to supply the lubricating oil to the backup roll and the work roll to reduce the thrust force during this period. For example, assuming that the backup roll has a rotation speed of 62.8 rpm, the rolling load is 1271 tons, and the thrust coefficient is always applied when cross rolling is applied, the relationship between the thrust coefficient applied to the bearing and the backup roll is as shown in FIG. If the conventional cross mill application rate is 68% and the thrust coefficient average is 6% under the above conditions, the life of the thrust bearing of the backup roll of the cross mill stand is estimated to be 15 years. The application rate of 44% is 44%, so the life of the thrust bearing of the backup roll is 1.
It will be extended 5 times.

[Brief description of drawings]

FIG. 1 is a set-up flow chart of a rolling method according to the present invention.

FIG. 2 is a schematic view of a hot rolling line in the present invention.

FIG. 3 is a characteristic diagram showing a relationship between a bearing force and a plate crown on the delivery side of the mill.

FIG. 4 is a diagram showing a schedule composition ratio in the case where rolling is performed by prioritizing the cross angle and the method of the present invention is applied.

FIG. 5 is a characteristic diagram in which the relationship between the thrust coefficient and the life of the thrust bearing of the backup roll is estimated.

FIG. 6 is an explanatory diagram for explaining a relative sliding speed and thrust force during conventional work roll crossing.

FIG. 7 is an explanatory diagram showing the direction of thrust force acting on each roll.

FIG. 8 is a characteristic diagram showing a relationship between a cross angle and a thrust coefficient.

FIG. 9 is a characteristic diagram showing a relationship between a cross angle and the rolling stand delivery side plate crown.

[Explanation of symbols]

1 Continuous hot rolling mill 2 cross mill stand

─────────────────────────────────────────────────── --- Continuation of front page (72) Inventor Shinichi Kaga 3-1-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi factory (56) Reference JP-A-7-171605 (JP, A) Kaihei 6-198307 (JP, A) JP-A 9-327704 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (2)

(57) [Claims] 1. A least work rolls (WR1, WR2) and have a backup roll (BUR1, BUR2), and work rolls for controlling the strip crown cross angle control function and base
In <br/> rolling method of a single cross-rolling mill and a bindings control function, a phase in a predetermined bending force of the work roll (WR1, WR2) the bending controllable range of
When the applicable cross angle limit value is exceeded (4th step
103), in combination with the work roll cross angle controller and the bending control, than the cross angle Limited value
In the case of (5th step 104), the bending control is performed.
Rolling wherein the TURMERIC row strip crown control similar. 2. The cross angle of the work rolls (WR1, WR2)
If the limit value is less than 0.3 degrees, the work roll
(WR1, WR2) rolling method according to claim 1, wherein the cross angle is set to 0 degrees and performing only in strip crown control the Bendin <br/> grayed control.