JPS61186103A - Rolling method - Google Patents

Abstract

PURPOSE:To prevent sheet-end and roll marks without deteriorating the sheet shape of a rolling stock by making the oscillating sped of at least one of rolls, whose movements in their axial directions are controllable, not more than the specific ratio of a rolling speed, in rolling the stock by multiple rolls. CONSTITUTION:A sheet stock is rolled by a multi-high mill capable of controlling the movement of at least one of its plural rolls in the axial direction. At least one of the rolls controllable in their movements in the axial direction, a work roll 3 or 3', for instance, is made to oscillate in the axial direction so that the ratio of its oscillating speed to a rolling speed is <=1X10<-3>. Then, a sheet stock is rolled without producing sheet-end and roll marks by oscillating rolling rolls within the speed range mentioned above.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for rolling a plate, and more particularly to a pressing method that can control the shape of a rolled plate without impairing the surface properties of the plate.

<Prior art> In recent years, in the rolling work of metal plates such as steel, from the viewpoint of improving productivity and saving energy, there has been a demand for high-reduction rolling mills that can significantly reduce the plate thickness in - rolling times. The requirements for machining accuracy of plate thickness and shape are also becoming stricter. In order to meet this demand, in conventional multi-high rolling mills 1, for example, four-high rolling mills, six-high rolling mills, etc., various methods of bending the work rolls that come into contact with the rolled material have been implemented.

A typical example of this is explained based on FIG. 1. This is a four-high rolling mill, with a vertical roll bending device 1,
1', and is composed of an upper and lower pair of work rolls 3.3' and a pair of pump unrolls 4.4', which are movable in the roll axis direction according to changes in the width of the rolled material 2. The upper and lower work rolls 3゜3' are moved in opposite directions in the roll axis direction in accordance with the width of the rolled material 2, and the work rolls are bent to fully utilize the shape modification ability of roll bending. This is what we do.

Further, the second prisoner is a conventional six-high rolling mill, in which intermediate rolls 5.5' are respectively provided between the upper and lower work rolls 3°3' and backup rolls 4, 4' in the conventional rolling mill, and , intermediate roll 5.5"i are configured to be movable in the roll axis direction according to the width of the rolled material 2. Therefore, the intermediate roll 5.5"i is movable in accordance with the width of the rolled material 2.
5', the long end of the body matches both ends of the rolled material, or slightly inside the both ends of the plate as shown (center side of the board width)
At the same time, as in the case of the conventional example, the shape accuracy of the rolled material in the width direction is improved by moving the work rolls 3, 3' in the axial direction and using the roll bending devices @l, l'. The aim is to improve this even further.

Still, Figures 3 and 4 show the upper and lower work rolls 3.3'
, a continuous rolling mill consisting of upper and lower bank up rolls 4, 4' and an intermediate roll 5 provided between the upper work roll 3 and the upper bank up roll 4. The work rolls 3, 3' and the intermediate roll 5 are each normally Vertical roll bending knob devices 1, 1' are installed. Also.

The upper work roll 3 is disposed to be shifted appropriately to either the upper or downstream side in the rolling direction Z, and has approximately the same body length as the roll 3 in order to adjust the horizontal deflection of the roll 3 due to the rolling load P. The presser roll 6 is disposed on the shifted side, and a plurality of backup rolls 7 divided in the roll axis direction are disposed on the shifted side of the presser roll 6 to support the presser roll 6, and the upper workpiece is removed by the lowering device 8. It is configured to be movable in a straight line direction connecting the rotation centers of the roll 3 and the presser roll 6. Therefore, in a single rolling mill, the pressing force on the presser roll 6 is individually adjusted via the rolling down device 8 and the bank-up roll 7, and the change in pressing force is taken as a vertical displacement, and the deflection of the upper work roll 3 is adjusted to the roll cylinder. In addition to freely adjusting each part in the longitudinal direction, the shape of the rolled material 2 in the width direction can be controlled by using it in combination with the upper and lower workpiece a-ru 3. It is.

<Problems to be solved by the invention> In each of the previous 6C rolling mills, as the rolling progresses, the rolled material 2
The work rolls 3, 3' that come into contact with the rolls are deflected by the rolling load P, and a large local surface pressure is generated at the edge of the plate side, causing local wear of a considerable portion of the roll surface, resulting in so-called plate edge marks 15. . In addition, in the rolling mill shown in Fig. 2, the surfaces of the upper and lower work rolls 3, 3' and the bank unroll 4.4' have an intermediate roll 5.5'l which corresponds to the same length end. The surface of the roll causes local abrasion 16 due to the high local surface pressure generated in the part, and therefore, during rolling, the local abrasion 16 is transferred to the plate surface and becomes so-called roll marks, causing a deterioration in the quality of the plate. There is a problem.

On the other hand, in the rolling mill shown in Figs. 3 and 4,
Because the backup roll 7 is divided into multiple parts,
By pressing onto the surface of the presser roll 6 via the rolling down device 8.

A roll mark 17 corresponding to the long end of each bank-ang roll body is generated on the surface of the stamping roll 6 in the same manner as in the case of the conventional intermediate rolls 5 and 5' shown in FIG. 2, and this is transferred to the plate surface. be done.

The occurrence of such sheet edge marks and a-rule marks is a particularly serious problem in cold rolling mills, and there is a strong desire to develop a rolling method that eliminates these sheet surface defects. In order to solve the above-mentioned problems, the present applicant previously proposed in Japanese Patent Application No. 59-14241 that the rolls whose movement can be adjusted in the axial direction of the rolls are oscillated at a slow speed in the respective axial directions during rolling. We have proposed a rolling method that can control the shape of a rolled plate without damaging its surface properties by driving. The present invention is based on the results of further research into this rolling method, and aims to clarify the appropriate range that can be selected as the pre-column α oscillation rate.

Means for Solving the Problems> The rolling method of the present invention is a rolling method using a rolling mill having a plurality of rolls, at least one of which is movable and adjustable in the axial direction. , at least one of the axially adjustable rollers is oscillated in the axial direction so that the ratio of the oscillation speed to the rolling speed is less than or equal to IXIU-'.

Effect> By oscillating the rolls within the above-mentioned speed range, the plate material can be rolled without producing plate end marks or roll marks.

<Example> An example of the rolling method according to the present invention will be described below using a four-high rolling mill shown in FIG.

The specifications of the rolling mill used in this example are: upper and lower work roll diameter pw = 260 m, backup roll diameter DB = = 5
00mm, a-A/body length d=610mtx.

Using this four-high rolling mill, an experiment was conducted in which the work rolls were oscillated in the axial direction with the work rolls 3° and 3' in contact with each other, and the results shown in FIG. 5 were obtained. FIG. 5 shows actual measured values, with the horizontal axis representing the ratio of the oscillation speed to the roll circumferential speed, and the vertical axis representing the ratio of the off-rate movement resistance value to the inter-roll load, that is, the oscillation coefficient. The experimental conditions were: load between rolls PR=100,200
(tf) Roll circumferential speed e Va"too, 250('!
”). The circles in the figure are actually measured values, and the solid and broken lines are calculated values using the following equation (1).

・・・・・・・・・(1) Here, μ8: Oscillation coefficient (ratio of moving resistance value to inter-roll load) μ. Coefficient of friction between 20 and 2θ: Oscillation speed ratio (ratio of oscillation speed to roll circumferential speed) R: Equivalent roll radius (strike) P: Load between rolls (kgf) l: Roll body length (home) Li: Poisson Ratio G: Transverse elastic modulus of roll material (kgf-rrπ'') - means between rolls in contact. In the case of one experiment, 1 = 1 is between upper and lower work rolls, 1 = 2 is between work rolled backup roll It is between.

From FIG. 5, it was found that the relationship between the oscillation coefficient μ3 and the oscillation speed ratio 2θ can be estimated using the above equation (1).

Here, if the oscillation speed of the a-ru is increased, the oscillation coefficient increases, and therefore the thrust force acting on the roll increases, so from the viewpoint of the durability of the roll thrust bearing, there is naturally an upper limit value for the oscillation speed. considered to be a thing.

This will be explained by the following example. Assuming that the diameter f of the oscillating roll is 320 mm, the dynamic load rating C of the applicable thrust bearing is approximately 60 tf. The bearing life time is estimated by the following equation 12).

Here, L: Bearing life (hours) P: Bearing load (tf) C: Bearing dynamic load rating (tf) V: Bearing rotation speed (rpm) Considering a three-stand tandem mill as an example of rolling conditions, typical What is the pass schedule?

- No. stand Rolling load P. = 1200tf/m rolling speed VR = 200ri No. 13 stand rolling load P. = 900tf/sm rolling speed vR2 600゜ If the bearing life is required to be 2000 hours, the limit value pm of the bearing load can be calculated from the above equation 12).

,',Pm=32 ,゛,P=23 Considering a serially arranged rolling mill, the load between the rolls is equal to the rolling load, so the oscillation coefficient is as follows: The oscillation speed is the highest when there is contact, and if this case is applied to equation (1), the upper limit value of the oscillation speed ratio will be 5X1'O-'.

The inventors performed the above calculations for various roll diameters and thrust bearings. FIG. 6 is a diagram of the above calculation results when the rolls are in one-point contact, two-point contact, and three-point contact. As seen in this figure, in general, if the oscillation speed ratio is less than l The present invention was completed based on the discovery that rolling can be carried out without producing sheet edge marks or roll marks by properly maintaining the rolling process.

<Effects of the Invention> According to the rolling method of the present invention, it is possible to prevent the occurrence of plate edge marks and roll marks without impairing the ability to control the shape of the plate depending on the rolling pattern, which contributes to improving the quality of the rolled plate. is huge.

[Brief explanation of the drawing]

1 and 2 are schematic front views of a four-high rolling mill and a long-leg rolling mill to which method 1 of the present invention is applied; FIGS. 3 and 4 are schematic side views and front views of a three-high rolling mill; 6 and 6 are diagrams showing the relationship between the oscillation speed ratio of the roll and the oscillation coefficient. In the drawings, 1 and 1' are roll bending devices, 2 is a rolling material, 3 and 3' are work rolls, 4 and 4' are bank unrolls, 5 and 5' are intermediate rolls/I/, and 6 is a presser roll. , 7 is a backup roll, and 8 is a compression bag U. Patent Applicant: Mitsubishi Heavy Industries, Ltd. Patent Attorney: Shibu Mitsuishi (and 1 other person) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Million L-+48pb

Claims (1)

[Claims] A method of rolling a plate material using a rolling mill having a plurality of rolls, at least one of which is adjustable in movement in the axial direction, the method comprising: A rolling method characterized in that the oscillation rate is moved in the axial direction so that the ratio of the oscillation speed to the rolling speed is 1x10^-^3 or less.