JPH10277619A - Device and method for hot rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for rolling raising the stability of rolling when a sheet is threaded and tailed off at the time of hot rolling. SOLUTION: In a hot rolling device having upper and lower work rolls and back-up rolls which are rotated by contacting with the work rolls, the upper and lower work rolls 1, 2 are offset to the back-up rolls 3 on the outlet side of the rolling direction. The difference between the diameters of the upper and lower work rolls is 0.1-1 mm. A device 5 for imparting horizontal force from the inlet side of the rolling direction to at least either of the upper or lower work rolls is provided. The work roll 1 on the side of larger diameter is incorporated into the side having a horizontal force imparting device 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling apparatus and a rolling method for dramatically improving the rolling stability at the time of passing a sheet or removing a tail, which is a problem in hot rolling, especially hot rolling of thin sheets.

[0002]

2. Description of the Related Art One of the remaining problems in hot finish rolling of a thin sheet in which a plurality of stands are continuously rolled is a threading instability. This is due to the fact that the material bends in the width direction and does not bite when rolling is started and the material bites into the roll bite of the rolling mill, and when rolling is completed and the material passes through the roll bite of the rolling mill. This causes the rolling to be stopped, or the plate breaks to damage the roll. To prevent this, the rolling mill operator adjusted the leveling (distribution in the width direction of the roll gap) by observing the way the material travels (bending) when the previous material was rolled. .

In recent years, attention has been paid to the fact that there is a relationship between the difference in the rolling load detected on the driving side and the driving side of the rolling mill and the deviation in the width direction of the plate. A technique has been developed to avoid leveling instability by operating leveling (Japanese Patent Application Laid-Open No. 61-219411).

Further, a control method has been proposed in which the leveling operation is performed by measuring the amount of deviation of a material in the width direction between stands (Japanese Patent Application Laid-Open No. 61-143016).

[0005] However, the stand between the rolling mills where the threading instability occurs is 5 to 6 m, while the rolling speed is up to 1 / min.
The speed is as high as 500 m. Therefore, the time required to pass between the stands is very short, about 0.2 seconds, and it is difficult to achieve an effect even by the above technique.
Furthermore, regarding JP-A-61-219411, the factors that cause the difference in the rolling load are not only the deviation in the width direction of the material, but also the deviation in the distribution in the width direction of the sheet thickness and the deformation resistance of the material.
Differences in the elastic deformation characteristics of the rolling mill between the driving side and the driving side are also considered, and it is necessary to appropriately classify these causes, which makes control difficult.

Further, the displacement of the roll bearing box is measured and the liner metal is replaced when the displacement exceeds a set value so that the clearance between the work roll bearing box and the housing metal of the rolling mill is controlled to a certain value or less. It has been proposed (JP-A-4-210808).

[0007] According to this known technique, rolling can be stabilized if the displacement of the bearing box is restrained, but a certain amount of clearance is required due to a change in roll gap for controlling the sheet thickness and smoothness when changing rolls. In addition, it is not clear under what circumstances the roll bearing box moves, and there is a possibility that wasteful facility management work will increase. Further, since the clearance existing between the roll bearing box and the work roll is not restrained at all, the position of the rolling roll is not completely stabilized.

[0008]

As a result of investigation by an actual rolling mill by the present inventors, and from Japanese Patent Application Laid-Open No. 4-210808, the work roll is located at a stable position, and before and after rolling or during rolling. It was found that the above-mentioned instability of threading was drastically improved if the plate was not moved in the rolling direction.

In the apparatus, the work roll is set in a state called offset, which is arranged so as to be displaced relative to the counter roll in the rolling direction (FIG. 7). This offset amount is usually 5 mm or more, though it depends on the strength of the bearing. It is considered that the offset gives a horizontal component to the contact force between the work roll and the copy roll, and the work roll is pressed in the offset given direction to be stable.

[0010] However, as a result of the investigation of the actual rolling by the inventors, it has been observed that the work roll may move in the rolling direction, particularly when the material bites into the rolling mill and when the material comes off. In the past, the cause was not clarified because it is a behavior that can not be considered in the normal force relationship,
As a result of detailed observation of actual rolling by the inventors, it has been clarified that this phenomenon is caused by the following causes. That is,
In the actual rolling, when the rotation speeds of the upper and lower work rolls are the same and the diameters of the work rolls are slightly different, the speeds of the upper and lower work rolls are slightly different. When the upper and lower work rolls come into contact after the material comes out of the rolling mill, a torque in the opposite direction is generated according to the subtle difference in the speed of the upper and lower work rolls. This is a phenomenon in which it moves in the direction opposite to the direction in which it was pressed.

[0011] This phenomenon is caused by the fact that the rolling mill is an elastic body and the roll gap is widened by a large rolling load during rolling.
As soon as rolling is completed, this elastic deformation returns to the original position and the roll gap becomes smaller.This occurs when the finished plate thickness of the rolled material is thin, or because the rolling load is high, the roll gap setting value is increased. Easy to occur when small.

Further, as shown in FIGS. 8 and 9, the horizontal force generated by the contact between the upper and lower work rolls and the gap between the upper and lower work rolls and the gap between the upper and lower work rolls and the contact load between the upper and lower work rolls are shown in FIGS. It turned out that I could organize it. When the difference between the upper and lower work roll diameters is small (0.05 mm), the positive and negative of the horizontal force are reversed. This is because when the diameter difference between the upper and lower work rolls is less than 0.1 mm, the roll diameter changes due to thermal expansion and abrasion during rolling, and the direction of torque at the time of work roll contact changes.

The pressing force generated by the offset with the stay roll is usually about 1% of the contact load. It has been confirmed that the pressing force of the work roll due to the circulating torque is several times the pressing force due to the offset (FIG. 10). If the pressing force due to the offset acts in the opposite direction, the work roll and the bearing box move easily. I will.

When rolling is started after the material is entrapped, the roll gap is opened and the upper and lower work rolls are separated from each other, so that the torque generated by the contact disappears. Move in the direction of. In FIG. 11, when the work roll is offset to the exit side in the rolling direction with respect to the counter roll and the upper work roll is large, a) between the bars (after the rolled material has passed through and before the next material is rolled), and b) rolling It shows the horizontal force in the rolling direction acting on the work roll at the time.

On the other hand, it is known that the front and rear ends of a material in a hot finish rolling mill do not maintain a rectangular shape but have a tongue shape or a fish tail shape. In addition, since the above-mentioned rolled material has various width asymmetries, rolling does not start at the same time in the width direction when the rolled material bites into the rolling mill or loses its tail.
Therefore, at the time of biting, non-contact from the state where the upper and lower work rolls are in contact with each other does not necessarily occur simultaneously in the roll body length direction, and only one of the driving side and the driving side is first moved in the offset direction. There are cases.

Similarly, when the tail roll comes off, contact between the upper and lower work rolls does not start at the same time, and only one of the driving side and the driving side is first moved in the direction opposite to the offset.

For example, let us consider a case where the work roll is offset with respect to the copy roll in the rolling direction.

[0018] The upper and lower work rolls are pressed against the roll-out side during steady rolling. However, when the setting of the roll gap is small, the upper and lower work rolls come into contact with each other because there is no rolling load when rolling is not performed, and the large-diameter work roll moves so as to be pressed to the entry side in the rolling direction. When the work roll moves in the rolling direction, the roll gap changes because the work roll rides on the stay roll due to offset with the stay roll. That is, if the amount of movement of the work roll in the rolling direction in the width direction is different, the change in the roll gap is also different in the width direction, and the rolling reduction is different in the width direction. Then, the board is bent in the width direction, and it is considered that the passing instability occurs as described above.

The inventor has devised the following method to prevent this. Basically, when the work roll moves by the mechanism described above, if the offset is set on the exit side in the rolling direction, the work roll on the small diameter side is always pressed to the exit side in the rolling direction, and from the housing Since the clearance between the bearing box and the work roll from the bearing box is eliminated, it is in a stable position without taking any special measures.

On the other hand, the work roll on the large-diameter side largely moves each time the work roll comes into contact with the work roll. Specifically, a device for applying a horizontal force from at least one of the upper and lower work rolls from the side opposite to the offset, that is, the rolling direction entry side, is installed, and a large-diameter work roll is incorporated on the side where the horizontal force applying device is installed. At least during the time when the work roll contact is generated and the force pressing in the entry side acts, that is, from the time when the material passes through the bottom to the time when the next material passes, the large-diameter work roll is applied by applying the horizontal force from the entry side. Of the work roll to the entry side in the rolling direction, and a clearance between the housing and the bearing box and a clearance between the bearing box and the work roll to eliminate the clearance between the work roll and the work roll.

When the upper and lower work rolls come into contact with each other,
Although a force in the direction of the rolling entry is generated in the large-diameter work roll, the difference in diameter between the upper and lower work rolls is 0.1 mm as shown in FIGS.
If it is less than 1, it has been observed that the size of the roll diameter changes due to thermal expansion and wear during rolling, and the direction of the torque at the time of contacting the work roll may change. It was also observed that when the difference in roll diameter was 1 mm or more, slippage occurred between the work rolls when the upper and lower work rolls contacted, and the roll and product surface properties deteriorated. Therefore, the diameter difference between the upper and lower work rolls is set to 0.1 mm or more and 1 mm or less.

Thus, according to the present invention, with regard to the rolling device, the upper and lower work rolls are offset to the exit side in the rolling direction with respect to the counter roll, and the difference between the upper and lower work roll diameters is 0.1 mm or more and 1 mm or less. And a device for applying a horizontal force to at least one of the upper and lower work rolls from the entry side in the rolling direction, and incorporating a large-diameter work roll on the side having the horizontal force application device.

Further, the present invention relates to the rolling method,
The upper and lower work rolls are offset to the exit side in the rolling direction with respect to the counter roll, and the difference between the upper and lower work roll diameters is 0.1 m.
m or more and 1 mm or less, and a horizontal force is applied to the large-diameter work roll from the entry side in the rolling direction at least from the time when the material passes through to the time when the next material passes.

According to the measurement by the inventors, when the upper and lower work rolls come into contact with each other before the material passes, the force on the large-diameter roll toward the rolling-in side is at most 5 in the range of actual operation.
It is less than 0 ton (about 45 ton). Therefore, to always stabilize the large-diameter work roll, a horizontal force of 50 ton or more may be applied. The upper limit of the horizontal force is determined by the smoothness when changing the roll gap by controlling the thickness and the strength of the work roll bearing box. This value is usually 10
Although it is considered to be 0 ton or more, it depends on the rolling mill and is not particularly limited. Accordingly, in the rolling method of the present invention, it is preferable that the horizontal force applied to the large-diameter work roll is always 50 ton or more.

As shown in FIGS. 8 and 9, the horizontal force generated by the contact between the upper and lower work rolls and the gap between the upper and lower work rolls or the difference between the upper and lower work rolls is determined by the difference between the upper and lower work rolls. We can arrange by load.
Therefore, in order to always stabilize the large-diameter work roll, the horizontal force applied by the horizontal force applying device may not always be constant, and is calculated from the roll diameter difference and gap value, or the roll diameter difference and the upper and lower work roll contact loads. What is necessary is just to be larger than the entered inward direction force. Accordingly, in the rolling method of the present invention, it is preferable that the horizontal force applied to the work roll is changed according to the diameter of the upper and lower work rolls and the gap set value of the rolling mill.

Further, it is preferable that the horizontal force applied to the work roll is changed in accordance with the diameter of the upper and lower work rolls and the contact load of the upper and lower work rolls before passing the material through.

The present invention also holds true for the magnitude relationship between the diameter of the work roll and the diameter of the work roll with respect to the rolling direction, which is opposite to the above relationship. That is, in the above-mentioned content of the present invention, the offset of the upper and lower rolls in the rolling direction is given to the entrance side instead of the exit side, and the horizontal force applied in at least one of the upper and lower rolls in the rolling direction to the exit side is changed to the exit side. And the work roll incorporated on the side having the horizontal force applying device is made smaller in place of the larger one.

[0028]

FIG. 1 shows an embodiment of the apparatus according to the present invention. 1 (A) and 1 (B), 1 is a large-diameter work roll, 2 is a small-diameter work roll, 3 is an upper and lower stay roll, and 4 is a work roll bearing box (in FIG. 1 (A), a bearing box). Is omitted). Although the rolling direction is shown in FIG. 1, the upper and lower work rolls 1 and 2 are offset with respect to the staying roll 3 toward the rolling direction. Reference numeral 5 denotes a horizontal force applying device installed so as to be in contact with the large-diameter work roll 1. The horizontal force applying device 5 includes a holding roll 6, a holding roll bearing box 7, and a cylinder 8.
Are supported by a housing (not shown). The diameter difference between the large-diameter work roll 1 and the small-diameter work roll 2 is 0.1.
mm or more and 1 mm or less.

FIG. 2 shows a modification of the embodiment of FIG. 1, in which the horizontal force applying device 5 is divided into two parts and arranged. In FIG. 2, 2
The horizontal force applying device 5 need not be equally or symmetrically divided. Further, the horizontal force applying device 5 may be installed so as to avoid the place where the material passes.

FIG. 3 shows another modification, in which the horizontal force applying device 5 is installed at the neck of the driving side or the driving side of the work roll while avoiding the place where the material passes.

FIG. 4 shows still another modification in which the horizontal force applying device 5 is installed outside the work roll bearing box 4.

Although the large-diameter work roll 1 is located on the upper side in FIGS. 1 to 4, the lower roll may have a large diameter and the lower roll may be provided with a horizontal force applying device 5. The horizontal force applying device 5 is installed horizontally on the entry side of the large-diameter work roll 1 in the rolling direction. However, any device can be used as long as it can apply a horizontal force and does not hinder rolling. For example, a horizontal force may be applied diagonally from above or below, or a horizontal force may be applied to a position shifted from the axis of the large-diameter work roll 1. The horizontal force applying device may be installed together with the upper and lower work rolls. The form of the horizontal force applying device may be other than FIGS.

When rolling is performed in such a configuration, when the gap setting value is large and the upper and lower work rolls do not come into contact with each other, such as a material having a large thickness, a force pressing the large-diameter work roll 1 toward the rolling direction is exerted. Therefore, the horizontal force may or may not be applied. When the upper and lower work rolls contact each other with a small gap setting value such as a thin material or a hard material, a horizontal force is applied by the horizontal force applying device 5 at least from the time when the material passes through the trailing edge to the time when the next material passes. I do.

According to the measurement results of the present inventors (FIGS. 8 and 9), the force to move in the rolling direction entry side is 50 ton at maximum.
Below (about 45 tons). Therefore, when the magnitude of the horizontal force is always constant, it is desirable that the horizontal force is always 50 ton or more in order to cover the range of the horizontal force in the entry direction generated by the contact of the work roll.

FIG. 5 shows another embodiment. In FIG. 5, 9 is a horizontal force setting device, 10 is a horizontal force control device, and 11 is a load cell for measuring horizontal force. The load cell 11 is installed between a housing (not shown) and the horizontal force applying device 5. When rolling is performed in such a configuration, the horizontal force setting device 9 is used.
The horizontal force setting device 9 calculates the horizontal force set value and outputs it to the horizontal force control device 10. The horizontal force control device 10 adjusts the horizontal force application device 5 so that the horizontal force detected by the load cell 11 becomes a set value. At this time, the form of the horizontal force applying device may be any of those shown in FIGS.

FIG. 6 shows still another embodiment. FIG.
Numeral 9 is a horizontal force setting device, 10 is a horizontal force control device, 11 is a load cell for measuring horizontal force, and 12 is a load cell for measuring rolling load and contact load between upper and lower work rolls. The load cell 11 is installed between a housing (not shown) and the horizontal force applying device 5. When rolling is performed in such a configuration, the upper and lower work roll diameters are input to the horizontal force setting device 9 from the host computer, while the upper and lower work roll contact loads measured by the load cell 12 are input. The horizontal force setting device 9 calculates a horizontal force set value and outputs it to the horizontal force control device 10. 10 adjusts the horizontal force applying device 5 so that the horizontal force detected by the load cell 12 becomes a set value. At this time, the form of the horizontal force applying device may be any of those shown in FIGS.

[0037]

[Embodiment] In a rolling mill having a drive system in which the rotation speeds of the upper and lower work rolls are the same, a device for applying a constant horizontal force to the upper work roll in the rolling direction outward direction is installed, and the upper work roll diameter is reduced. It was decided to operate with a diameter of 0.3 to 0.7 mm larger than the work roll diameter. As a result of adjusting the horizontal force applying device and performing rolling at an applied horizontal force of 10 tons, the work roll replacement frequency due to instability in passing was not much different from the conventional one. Therefore, when the applied horizontal force was set to 30 tons, the work roll replacement frequency was about 75% of the conventional one. Furthermore, when the applied horizontal force was set to 50 tons, the frequency of reassembly was reduced to 40% or less of the conventional one, and the stability of rolling could be significantly improved. Note that the applied horizontal force is 12
When the test was carried out at 0 ton, the change frequency was not so different from about 30 to 40% of the conventional one. Conversely, when the horizontal force was 100 ton or more, it became difficult to change the roll gap by controlling the sheet thickness. . Therefore, the horizontal force is set to 50 ton, but the work roll change frequency due to the instability of the threading is stable at 30 to 40% of the conventional frequency.

Further, when a device for changing the horizontal force applied to the work roll according to the upper and lower work roll diameters and the gap set value of the rolling mill was installed and the same test was carried out, the horizontal force of 50 tons or more was not always applied. However, the frequency of changing work rolls due to instability in passing was 30 to 40% of the conventional frequency. Similar results were obtained even when the horizontal force was changed according to the upper and lower work roll diameters and the upper and lower work roll contact loads before passing the material by partially improving the apparatus.

In the embodiment described above, an embodiment in which the size relationship between the entrance and exit sides with respect to the rolling direction and the diameter of the work roll is the reverse of this relationship also holds. That is, in the above-mentioned content of the present invention, the offset of the upper and lower rolls in the rolling direction is given to the entrance side instead of the exit side, and the horizontal force applied in at least one of the upper and lower rolls in the rolling direction to the exit side is changed to the exit side. And the work roll incorporated on the side having the horizontal force applying device is made smaller in place of the larger one.

[0040]

As described above, according to the apparatus of the present invention, the horizontal force applying device is installed on the large-diameter or small-diameter work roll, and the large-diameter or small-diameter work roll is rolled out or in. The horizontal force is applied to prevent the large or small diameter work roll from moving in or out when the upper and lower work rolls come into contact, stabilizing the position of the work roll, and making the passing plate unstable. , The frequency of work roll changeover was greatly reduced, and the rolling stability was dramatically improved. Further, according to the method of the present invention, the stability at the time of rolling under the apparatus of the present invention can be enhanced.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, wherein (A) is a side view,
(B) is BB sectional drawing in (A).

FIG. 2 shows a modification of the apparatus of FIG. 1, wherein (A) is a side view,
(B) is BB sectional drawing in (A).

3A and 3B show another modified example of the apparatus in FIG. 1, in which FIG. 3A is a side view, and FIG. 3B is a sectional view taken along line BB in FIG.

FIGS. 4A and 4B show still another modified example of the device in FIG. 1, wherein FIG. 4A is a side view, and FIG. 4B is a sectional view taken along line BB in FIG.

FIG. 5 is a side view showing another embodiment of the present invention.

FIG. 6 is a side view showing still another embodiment of the present invention.

FIG. 7 is an explanatory diagram of an offset between a work roll and a copy roll.

FIG. 8 is a diagram illustrating a relationship between a horizontal force and a set gap value when the upper and lower work rolls are in contact with each other.

FIG. 9 is a diagram showing a relationship between a horizontal force at the time of contact with the upper and lower work rolls and a load at the time of contact.

FIG. 10 is a diagram showing a relationship between a horizontal force and a load at the time of contact.

11A and 11B are explanatory diagrams of a horizontal force acting on a work roll (when the work roll is offset to the output side and the upper work roll is large), wherein FIG. Shows the time of rolling.

[Explanation of symbols]

 1 Large-diameter work roll 2 Small-diameter work roll 3 Copy roll for upper and lower work rolls

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Matsuo Yoshimoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (10)

[Claims] 1. A hot rolling apparatus having upper and lower work rolls and a stay roll rotating in contact with the upper and lower work rolls, wherein the upper and lower work rolls are offset from the stay roll in the rolling direction exit side; Is 0.1
mm or more and 1 mm or less, a device for applying a horizontal force to at least one of the upper and lower work rolls from the entry side in the rolling direction is provided, and a large-diameter work roll is incorporated on the side having the horizontal force application device. A hot-rolling apparatus characterized by the above-mentioned. 2. The upper and lower work rolls are offset to the exit side in the rolling direction with respect to the counter roll, so that the difference between the upper and lower work roll diameters is 0.1 mm or more and 1 mm or less, and at least when the material passes through the trailing edge, the next material passes through. A hot rolling method, wherein a horizontal force is applied to the large-diameter work roll from the entry side in the rolling direction until the sheet is rolled. 3. The hot rolling method according to claim 2, wherein the horizontal force applied to the large-diameter work roll is always 50 ton or more. 4. The hot rolling method according to claim 2, wherein the horizontal force applied to the work roll is changed in accordance with the upper and lower work roll diameters and a gap set value of a rolling mill. 5. The hot rolling method according to claim 2, wherein the horizontal force applied to the work roll is changed in accordance with the diameter of the upper and lower work rolls and the contact load of the upper and lower work rolls before passing the material through. 6. A hot-rolling apparatus having upper and lower work rolls and a stay roll rotating in contact with the upper and lower work rolls, wherein the upper and lower work rolls are offset with respect to the stay roll in the rolling direction entry side, and the upper and lower work roll diameters are reduced. Is 0.1
mm or more and 1 mm or less, a device for applying a horizontal force to at least one of the upper and lower work rolls from the exit side in the rolling direction is provided, and a work roll on the small diameter side is incorporated on the side having the horizontal force application device. A hot rolling apparatus. 7. The upper and lower work rolls are offset to the entry side in the rolling direction with respect to the counter roll, and the difference between the upper and lower work roll diameters is set to 0.1 mm or more and 1 mm or less. A hot rolling method, wherein a horizontal force is applied to the work roll on the small diameter side from the outside in the rolling direction until the sheet is rolled. 8. The hot rolling method according to claim 7, wherein the horizontal force applied to the work roll on the smaller diameter side is always 50 ton or more. 9. The hot rolling method according to claim 7, wherein the horizontal force applied to the work roll is changed in accordance with the upper and lower work roll diameters and the gap set value of the rolling mill. 10. The hot rolling method according to claim 7, wherein the horizontal force applied to the work roll is changed according to the diameter of the upper and lower work rolls and the contact load of the upper and lower work rolls before passing the material through.