JPH0688054B2 - Method of changing work rolls in rolling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a rolling mill capable of easily controlling the shape of a plate over a large range by relatively moving the upper and lower work rolls having an uneven initial crown in the axial direction. The present invention relates to a method for changing the upper and lower work rolls.

[Prior Art] In recent years, in the plate rolling, the plate crown, that is, the change in the plate thickness in the width direction and the flatness have been emphasized. As a countermeasure against this, an uneven initial crown is provided on the upper and lower work rolls that can be relatively moved in the roll axis direction. The rolling mill side, which is provided so as to be point-symmetric with respect to each other, has recently been disclosed in Japanese Patent Publication No. 51-7635 and JP-A-63-36912.
It is proposed in the technology described in the publication.

The rearrangement of the upper and lower work rolls in this rolling mill has always been to simply replace a used roll with a new initial crowning roll.

[Problems to be Solved by the Invention] However, in the rolling mills described in JP-B-51-7635 and JP-A-63-36912, the diameter distribution in the axial direction of the upper and lower work rolls provided with the concave-convex initial crown is Since it has a part where the roll diameter is larger than other parts and a part where the roll diameter changes greatly, there is a part where the roll surface pressure locally becomes large between the reinforcing roll and the work roll, and the reinforcing roll with relatively low hardness Had a problem of shortening the life of the machine and causing a roll accident called spalling.

For this reason, it is conceivable to give the backup roll a concave-convex initial crown that is point-symmetrical to each other and roll the roll by moving it axially together with the work roll, but in other respects, such as making the moving mechanism and control more complicated. A problem arises.

[Means for Solving the Problems] The present invention has solved the above-mentioned problems, and the summary thereof is as follows.

1 The upper and lower work rolls, which are arranged between the upper and lower reinforcement rolls, are provided with concave and convex initial crowns so as to be point-symmetric with respect to each other, and the width, thickness and rolling load of the material to be rolled are changed according to changes in rolling conditions. , A rolling mill in which the upper and lower work rolls are relatively moved in the axial direction relative to each other to control the crown of a material to be rolled by the upper and lower work rolls, in regard to replacement of the upper and lower work rolls, a combination of the upper and lower work rolls after recomposition Is performed upside down or left-right or reversely to the combination of the upper and lower work rolls before the rearrangement. 2 Reworking method of the work rolls in rolling Crowns are given as point symmetry as possible, and the upper and lower work rolls are axially aligned with each other according to changes in the rolling conditions such as width, thickness and rolling load of the material to be rolled. In the rolling mill that controls the crown of the material to be rolled by moving the upper and lower work rolls relative to each other, the roll surface pressure distribution between the upper and lower work rolls that are in phase contact with the upper and lower reinforcing rolls is after the recombining and before the recombining. The method of reassembling work rolls in rolling is characterized in that the combination of the upper and lower work rolls is the same as that of the upper and lower work rolls before and after the reassembling process. When changing the work rolls to be performed as described above, the cumulative rolling length in each of the combinations is adjusted to be substantially equal, and the work roll changing method in the rolling according to the above 1 or 2, 4 One change of upper / lower reinforcing rolls During the period, when changing the work rolls, the combination of the upper and lower work rolls is performed upside down or left and right with the combination of the upper and lower work rolls before changing The method for changing the work rolls in rolling according to the preceding item 1 or 2, wherein the cumulative value of the product of the load and the rolling length for each rolling pass in each of the combinations is adjusted to be substantially equal. During the period, when the combination of the upper and lower work rolls is vertically or horizontally reversed from the combination of the upper and lower work rolls before the rearrangement, the cumulative rolling length in each of the combinations is adjusted to be substantially equal. Method of changing work rolls in rolling as described in 1 or 2 6 When changing work rolls such that the combination of upper and lower work rolls is the same as that of the upper and lower work rolls before and after the change, upside down or left and right, within the life of the upper and lower reinforcing rolls. The cumulative value of the product of the load and the rolling length for each rolling pass in each of the above combinations is adjusted to be substantially equal. METHOD recombinant of the work roll in the rolling [for work will be described below action method brings the present invention with reference to the drawings.

FIG. 1 is an explanatory view of an initial crown of a work roll according to the present invention. In the figure, 1 is a steel plate to be rolled, 2 is an upper work roll, 3 is a lower work roll, and 4 and 5 are flat upper reinforcing rolls and lower reinforcing rolls, respectively.

In Fig. 1, the upper and lower work rolls are movable relative to each other in the direction of the roll axis marked with →, but no matter which position they are moved, the curve m in Fig. 2 is shown between the work roll and the reinforcing roll. Such a non-uniform pressure distribution occurs in the roll axis direction. Since the integral value of this pressure distribution is equal to the rolling reaction force, as described above, if the same initial crown of unevenness is given to each of the work rolls facing the reinforcing rolls, the uniform rolls shown by the straight line n in FIG. It has a wide pressure distribution.

In FIG. 2, the range in which the curve m is higher than the straight line n is a range in which the wear and rolling fatigue of the work roll and the reinforcing roll are increased and the life is shortened as compared with the other portions.

As shown in “Iron and Steel Handbook III (1)” P262 (published by 55.5.15) edited by the Japan Iron and Steel Institute, work rolls are recombined at 3000 to 5000 tons, and the amount of roll grinding is determined mainly by improvement of heat crack and roll hardness reduction To be done. On the other hand, since the reinforcing roll has a long roll changing cycle, the grinding amount is mainly determined by the amount of the fatigue layer removed to prevent spalling. Therefore, the work rolls are replaced within a period when rolling fatigue does not become a problem, and the work rolls are ground to an amount that does not cause a problem from the viewpoint of the fatigue layer. Depending on the state of occurrence of this fatigue layer, the roll is
The grinding amount of the roll largely depends on the life of the roll, and if the grinding amount is not sufficient, there is a high risk of spalling. According to the test results of the inventors of the present invention, this fatigue layer is proportional to the cumulative rolling length as shown in FIG. 3 in rolling with a substantially constant rolling load. Further, when the rolling load changes variously, the fatigue layer is proportional to the cumulative value of the product of the load and rolling length for each rolling pass. From this, in order to prolong the life of the reinforcing rolls or to reduce the risk of causing spalling, the method of the present invention is such that the upper and lower work rolls that are in phase contact with the upper and lower reinforcing rolls are rearranged vertically or horizontally, and the roll surface By rolling the pressure distribution after the reassembling and before and after the reassembling alternately, the rolling fatigue of the reinforcing rolls is dispersed in the longitudinal direction of the roll cylinder, and the life of the reinforcing rolls is extended.

[Examples] Table 1 shows the results when a steel sheet having a sheet thickness of 4.5 to 40 mm, a sheet width of 1.5 to 5 m, and a sheet length of 10 to 60 m was rolled for approximately 100,000 Ton within one recombining period of the reinforcing rolls together with a comparative example. .

In Examples 1 to 3 and the conventional example of the method of the present invention, an uneven initial crown is applied to the upper and lower work rolls, respectively.
The roll curve at that time has a shape represented by the following equation (1).

f (X) = y (X ) = y 3 (X) · y 4 (X) (1) _{However, y 3 (X) = 0.2} · (exp (-0.07x 2) + exp (-0.63x 2)) (2) y ₄ (X) = X ³ −1.6X (3) (where x is a unit of m) The initial crown of the reinforcing roll was not provided, and the roll was a flat roll.

The rolling of this example was performed by a quadruple reversible rolling mill shown in Table 2.

As shown in Table 1, in the case of Examples 1 to 3 using the method of the present invention, the fatigue layer of the roll was removed and the same value as before use was obtained, as compared with the conventional example performed under substantially the same rolling conditions. It can be seen that a roll grinding amount of about 2/3 is sufficient to return to the roll hardness of.

[Effect of the Invention] According to the present invention, the upper work roll and the lower work roll are provided with substantially the same concave and convex initial crowns so as to be point-symmetric with respect to each other, and the upper and lower work rolls are relatively moved in the axial direction relative to each other. The rolling surface pressure distribution between the upper and lower work rolls in phase contact with the upper and lower reinforcing rolls in a rolling mill controlling the crown of the material to be rolled by the upper and lower work rolls,
By changing to the same or another upper and lower work rolls so that the left and right after changing rolls are opposite to each other,
It reduces the life of the upper and lower reinforcing rolls and solves the problem of roll accident called spalling.It has an industrial effect such as improvement of rolling productivity, improvement of rolling quality, omission of finishing process such as straightening, etc. It's a lot.

[Brief description of drawings]

FIG. 1 is an explanatory view of an initial crown of a work roll according to the present invention, FIG. 2 is a view showing a roll surface pressure distribution acting between a work roll and a reinforcing roll, and FIG. 3 is a view showing a rolling load with a substantially constant rolling load. It is a figure which shows the relationship between cumulative rolling length and fatigue layer depth. 1 ... Rolled material, 2 ... Top work roll, 3 ... Bottom work roll, 4 ... Top reinforcement roll, 5 ... Bottom reinforcement roll.

Claims (6)

[Claims] 1. An upper work roll and a lower work roll arranged between upper and lower reinforcing rolls are provided with concave and convex initial crowns so as to be point-symmetric with respect to each other. In accordance with a change, the upper and lower work rolls are relatively moved in the axial direction relative to each other, and in a rolling mill that controls the crown of the material to be rolled by the upper and lower work rolls, regarding the replacement of the upper and lower work rolls, the upper and lower parts after reassembly A method of recomposing work rolls in rolling, characterized in that the combination of work rolls is performed upside down or left-right opposite to the combination of upper and lower work rolls before recomposition. 2. The upper work roll and the lower work roll arranged between the upper and lower reinforcing rolls are provided with concave and convex initial crowns so as to be point-symmetric with respect to each other, and the width, thickness, and rolling load of the material to be rolled are controlled. Depending on the change, the upper and lower work rolls are relatively moved in the axial direction relative to each other, and in a rolling mill that controls the crown of the material to be rolled by the upper and lower work rolls, between the upper and lower work rolls in phase contact with the upper and lower reinforcing rolls. Of roll surface pressure distribution on the left and right sides after and after recomposition 3. When the work rolls are rearranged so that the combination of the upper and lower work rolls is vertically or horizontally opposite to the combination of the upper and lower work rolls before the rearrangement within one recombining period of the upper and lower reinforcing rolls, The method of reassembling work rolls in rolling according to claim 1 or 2, wherein cumulative rolling lengths in the combination are adjusted to be substantially equal. 4. Rolling in each of the above-mentioned upper and lower reinforcing rolls, when the combination of the upper and lower work rolls is performed upside down or left-right opposite to the combination of the upper and lower work rolls before the rearrangement within one recombining period. The method of reassembling work rolls according to claim 1 or 2, wherein the cumulative value of the product of the load and the rolling length for each pass is adjusted to be substantially equal. 5. Cumulative pressure in each of the above-mentioned upper and lower reinforcing rolls when the combination of the upper and lower work rolls is performed upside down or left-right opposite to the combination of the upper and lower work rolls before the rearrangement during the service life of the respective combinations. 3. The method of reassembling work rolls in rolling according to claim 1, wherein the extensions are adjusted to be substantially equal. 6. A rolling pass in each of the above-mentioned upper and lower reinforcing rolls, when the combination of the upper and lower work rolls is performed upside down or left-right opposite to the combination of the upper and lower work rolls before the rearrangement, during the service life of the upper and lower reinforcement rolls. 3. The method of reassembling work rolls in rolling according to claim 1, wherein the cumulative value of the product of the load and the rolling length for each is adjusted to be substantially equal.