JP2779282B2 - Rolling method of aluminum plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hot rolling an aluminum sheet by a rolling mill.

[0002]

2. Description of the Related Art Conventionally, in a method of hot rolling a metal sheet by a rolling mill, many technical developments have been carried out with the aim of improving the rolling speed and efficiency. As a result, the control of the shape of the sheet and the control of the thickness of the sheet in the rolling mill have reached almost satisfactory levels. However, improvement of the surface properties of the plate material is still mentioned as a problem. In particular, in the method of hot rolling an aluminum plate, surface defects are apt to occur in the plate, and the rolling conditions require careful attention.

[0003] There are various surface defects that occur in the aluminum plate material during hot rolling of the aluminum plate material, and one of them is a roll mark. The roll mark indicates uneven unevenness generated on the work roll during rolling,
Further, uneven roll coating caused by the uneven portion is transferred to the surface of the plate material, and the surface of the plate material becomes defective.

FIG. 1 shows a six-high rolling mill. Fig. 1 (a)
, 1 is a pair of work rolls, 2 is a pair of intermediate rolls, 3 is a pair of backup rolls, and the intermediate roll 2 and the backup roll 3 are auxiliary rolls. An aluminum plate 11 is conveyed while being sandwiched between work rolls 1 rotated by a rotation drive device (not shown). Here, if the work roll 1 has uneven uneven portions 1a, the uneven portions 1a are transferred to the surface of the aluminum plate 11 and roll marks 12 are formed on the surface of the aluminum plate 11.
Is formed.

[0005] In the case of the four-high rolling mill, similarly, when the work roll 1 has an uneven portion 1 a, a roll mark 12 is formed on the aluminum plate 11.

[0006]

Conventionally, when an intermediate roll or backup roll, which is an auxiliary roll for supporting a work roll, is subjected to extremely steep chamfering, a roll mark is generated on an aluminum plate. It has been known. The chamfer is a chamfer formed at the end of the auxiliary roll, for example, 3a formed at the end of the backup roll 3 as shown in FIG. 1 (b). The steep shape of the chamfer means that the slope is steep.

If the chamfer of the auxiliary roll has a steep gradient, the angle of the boundary between the straight portion and the chamfer in the auxiliary roll becomes sharp. Then, the boundary between the straight portion and the chamfer in the auxiliary roll scratches the surface of the work roll to form an uneven portion, and the uneven portion of the work roll damages the surface of the aluminum plate to generate a roll mark. I have.

Conventionally, no other knowledge has been obtained regarding roll marks other than knowledge about chamfers.
Therefore, as a measure against roll marks, the surface of the aluminum plate is prevented from being damaged by smoothing the degree of gradient of the chamfer and making the angle of the boundary between the straight portion and the chamfer in the auxiliary roll gentle. To suppress the occurrence of roll marks.

[0009] By the way, the chamfer is described in the literature (plasticity and processing, published by the Japan Society of Plasticity, VOL23, NO263, (1982-12)
Hot strip profile control using a chamfer backup roll on page 1152)
The work roll is formed on the auxiliary roll in order to enhance the crown control ability of the plate material. Unless the work roll is formed with a steep gradient to some extent, the effect of enhancing the crown control ability of the plate material cannot be expected.

Therefore, if the slope of the chamfer formed on the auxiliary roll is made gentle to suppress the generation of the roll mark, there is a problem that the effect of enhancing the ability of the work roll to control the sheet material crown cannot be expected.

Conventionally, in order to solve such contradictory conditions, an operator sets the dimensions and shape of the chamfer of the auxiliary roll and the rolling conditions in actual rolling, respectively. It was difficult to set an appropriate size and shape of the chamfer because of the limited conditions.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for rolling an aluminum plate material capable of taking appropriate measures for suppressing the occurrence of roll marks.

[0013]

The inventor of the present invention has conducted various studies on preventing the occurrence of roll marks in a method of rolling an aluminum plate.

It has been found that one of the causes of the roll marks on the aluminum plate is as follows.

An auxiliary roll (FIG. 1) which comes into contact with a work roll
The intermediate roll 2 corresponds to the 6-high rolling mill shown in FIG. )
Local plastic deformation occurs in the surface layer at a portion where the contact pressure with the work roll is high, and minute irregularities occur at the portion. The unevenness of the auxiliary roll damages the aluminum-coated surface of the work roll and forms an unevenness on the surface of the work roll. The uneven portion on the surface of the work roll forms a roll mark on the surface of the aluminum plate.

Therefore, the inventor of the present invention pays attention to the contact pressure between the work roll and the auxiliary roll, and adopts this contact pressure as a condition for preventing the occurrence of a roll mark. Furthermore, as a result of repeated studies, the inventor has found that when rolling is continuously performed at a roller rotation speed having a contact pressure of a certain value or more between the work roll and the auxiliary roll, a roll mark is formed on the surface of the aluminum plate material. Was found to occur.

Therefore, the rolling conditions are defined so that this condition (that the contact pressure between the work roll and the auxiliary roll at a certain value or more continues over a certain number of rotations of the work roll) is not satisfied. It was found that generation of roll marks on the surface can be suppressed.

The present invention has been made based on such findings.

That is, the method for rolling an aluminum sheet according to the present invention is a method for hot rolling an aluminum sheet using a rolling mill, wherein a threshold value of contact pressure between a work roll and an auxiliary roll of the rolling mill is used. The value of 600 MPa or more is integrated with the work roll rotation speed.
50,000 (Mpa times) or less.

[0020]

An embodiment of the present invention will be described.

The present invention relates to a method for rolling an aluminum plate in a six-high rolling mill shown in FIG. 1, for example, in which a contact pressure between a work roll and an auxiliary roll is specified, and rolling conditions for maintaining the contact pressure are specified. This is a method of rolling.

FIG. 2 shows an example of the distribution of the contact pressure between the work roll and the intermediate roll 2, which is an auxiliary roll that comes into contact with the work roll, under the rolling conditions of the aluminum sheet material adopted by the present invention. In the case of the pressure distribution A in FIG. 2, no roll mark was generated on the aluminum plate regardless of the number of rolled aluminum plates. On the other hand, in the case of the pressure distribution of B in FIG. 2, a roll mark was generated at a stage 15 minutes after the start of rolling.

From this, in the aluminum plate material,
It has been found that when the contact pressure between the work roll 1 and the intermediate roll 3 exceeds a certain threshold value and the work roll 1 rotates beyond a certain number of rotations, a roll mark is generated on the aluminum plate. .

The inventor has further conducted experiments, and as a result, has found an equation that specifically shows the above relationship. This is the following equation.

F = Amax (P−Pa, O) dN where A represents an integral symbol (the integral section is from roll replacement to the present), F: Roll mark generation evaluation (MPa · times) = 15000
(MPa times), P: contact pressure (MPa) between work roll 1 and auxiliary roll (intermediate roll 3), Pθ: between work roll 1 and auxiliary roll (intermediate roll 3) Contact pressure threshold value (MPa), = 600 MPa, N: work roll rotation speed. That is, this equation integrates the contact pressure between the work roll and the auxiliary roll with the threshold value of 600 MPa or more by the rotation speed of the work roll, and calculates the integration result by 150.
000 (Mpa times) or less.

The diagram shown in FIG. 3 shows the relationship between the function F and the presence or absence of a roll mark. According to this diagram,
It can be seen that the presence or absence of a roll mark can be predicted by the function F without fail.

Therefore, by performing rolling under rolling conditions excluding these conditions, it is possible to suppress the occurrence of roll marks.

The following method is an example of a method of rolling under rolling conditions excluding the conditions represented by the above formula.

During rolling, the function F is calculated online, and the function F reaches a limit value, ie, 150,000 (Mpa · times).
, The work roll 1 and the intermediate roll 2 are exchanged. Alternatively, the rolling conditions (pass schedule, material temperature, rolling speed, roll bender force, etc.) are adjusted so that the contact pressure between the work roll 1 and the intermediate roll 2 does not exceed the threshold value.

According to the above-described method, it is possible to easily set appropriate conditions for suppressing the occurrence of roll marks in hot rolling of an aluminum plate material. -Rule 1
Of the sheet material crown control ability can be secured.

The present invention is not limited to a six-high rolling mill, but can be applied to a four-high rolling mill. In this case, the auxiliary roll that comes into contact with the work roll becomes a backup roll.

The roll mark should be generated by considering the effect of roll wear due to the rolling ratio of the rolling mill. In the case of rolling an aluminum plate, the roll wear is relatively small.
The effect is not so significant and can be ignored.

[0033]

As described above, according to the method for rolling an aluminum sheet of the present invention, the roll mark is generated by defining the magnitude of the contact pressure between the work roll and the auxiliary roll of the rolling mill. It is possible to easily set appropriate conditions for suppressing the noise.

[Brief description of the drawings]

FIG. 1A is a perspective view showing a six-high rolling mill. (B) is a diagram showing a roller channel.

FIG. 2 is a diagram showing an example of a distribution of contact pressure between a work roll and an auxiliary roll.

FIG. 3 is a diagram showing a relationship between a function F and the presence or absence of a roll mark.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Work roll, 2 ... Intermediate roll, 3 ... Backup roller, 11 ... Aluminum plate material.

Claims (1)

(57) [Claims] 1. A method for hot rolling an aluminum sheet by a rolling mill, wherein a contact pressure between a work roll and an auxiliary roll of the rolling mill, the threshold value of which is 600 MPa or more, is determined by the rotation speed of the work roll. And integrate the result of this integration as 1
A method for rolling an aluminum sheet, wherein the method is specified to be 50,000 (Mpa times) or less.