JPH02268911A - Method for recombining operating rolls in rolling - Google Patents

Abstract

PURPOSE:To prevent lives of upper and lower reinforced rolls from shortening by making combination of an upper working roll with a lower working roll after they are recombined up and down inversely and right and left reversely to combination of the upper working roll with the lower working roll before they are recombined regarding the change of the upper and lower working rolls. CONSTITUTION:The upper and lower working rolls 2, 3 are changed before rolling fatigue comes in problem and since an ample amount irrespective of the fatigue layer is ground, a local increase of the surface pressure between the rolls is out of the question. However, in the upper and lower reinforced rolls, the state of generation of this fatigue layer controls an amount of grinding of the roll and determines the lives of the reinforced rolls and, further, an unsatisfactory amount of grinding is highly apt to cause spalling. Consequently, the upper and lower operating rolls 2, 3 coming in contact with the upper and lower reinforced rolls 4, 5 are recombined up and down inversely, or, right and left reversely, the distribution of the surface pressure of each roll between the rolls is reversed right and left alternately for rolling after and before the operating rolls are recombined, the rolling fatigue on the reinforced rolls 4, 5 are dispersed in the direction of the barrel lengths of the rolls and the lives of the reinforced rolls 4, 5 can be prolonged.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a rolling mill in which the shape of a plate material can be easily controlled over a wide range by relatively moving upper and lower work rolls having uneven initial crowns in the axial direction. , relates to a method for rearranging upper and lower work rolls.

[Prior art] In recent years, emphasis has been placed on the plate crown, that is, changes in the width direction of the plate thickness and flatness in plate rolling.As a countermeasure, an uneven initial crown is provided on the upper and lower work rolls, which are movable relative to each other in the roll axis direction. The rolling mill side, which has been given point symmetry with respect to each other, has recently been published in Japanese Patent Publication No. 51-7635 and Japanese Patent Application Laid-Open No. 1983-1989.
This is proposed in the technique described in Japanese Patent No. 3-36912.

The rearrangement of the upper and lower work rolls in this rolling mill involved simply replacing the used rolls with new initial crowning rolls.

[Problem to be solved by the invention] However, Japanese Patent Publication No. 51-71i35 and Japanese Patent Application Laid-open No. 63
In the rolling mill described in Publication No. 36912, the diameter distribution in the axial direction of the upper and lower work rolls provided with the uneven initial crown has a portion where the roll diameter is larger than other portions and a portion where the roll diameter changes greatly, so the reinforcing roll There are areas where the roll surface pressure is locally large between the work roll and the work roll.
This has the problem of shortening the life of the reinforcing roll, which has relatively low hardness, and causing a roll accident called spalling.

For this reason, it is conceivable to give the backup roll an uneven initial crown that is symmetrical with respect to each other and roll it together with the work roll in the axial direction, but this will cause problems in other aspects such as the moving mechanism and control becoming increasingly complex. The problem is neglected.

[i! Means for Solving the Problem] The present invention solves the above problems, and the gist thereof is as follows.

1. The upper work roll and the lower work roll are each provided with an initial crown of unevenness so as to be point symmetrical to each other, and the upper and lower work rolls are axially aligned with respect to each other according to changes in rolling conditions such as the width, thickness, and rolling load of the material to be rolled. In a rolling mill that controls the crown of the rolled material rolled by the upper and lower work rolls by moving relative to the upper and lower work rolls, when replacing the upper and lower work rolls, the combination of the upper and lower work rolls after reassembly is the combination of the upper and lower work rolls before reassembly. A method for rearranging work rolls in rolling, characterized in that rolling is carried out vertically or horizontally inverted In a rolling mill that moves the upper and lower work rolls relative to each other in the axial direction in response to changes in the rolling conditions of the load to control the crown of the material to be rolled that is rolled by the upper and lower work rolls, the upper and lower work rolls are brought into phase contact with the upper and lower reinforcing rolls. A method for rearranging work rolls in rolling characterized in that the roll surface pressure distribution between the upper and lower work rolls is reversed from left to right after rearrangement and before rearrangement. In the rolling according to item 1 or 2 above, the cumulative rolling extension in each of the combinations is adjusted to be approximately equal when the work rolls are rearranged so that the combination of the upper and lower work rolls is opposite to the combination of the upper and lower work rolls before the rearrangement. Work roll rearrangement method 4 During one rearrangement period of reinforcing rolls, when the work rolls are rearranged in such a way that the combination of upper and lower work rolls is vertically or horizontally opposite to the combination of upper and lower work rolls before rearrangement, the combination of the upper and lower work rolls is changed for each rolling pass in each of the above-mentioned combinations. Method 5 for rearranging work rolls in rolling according to the preceding clause 1 or 2, characterized in that the cumulative value of the product of the load and the rolling length is adjusted to be approximately equal. Rearrangement of work rolls in rolling according to item 1 or 2 above, characterized in that when rearranging the work rolls to be performed vertically or horizontally opposite to the previous combination of upper and lower work rolls, the cumulative rolling extension in each of the combinations is adjusted to be approximately equal. Method 6 During the life of the reinforcing roll, when the combination of upper and lower work rolls is reassembled vertically or horizontally opposite to the combination of upper and lower work rolls before reassignment, the load and rolling length for each rolling pass in each of the above combinations are calculated. Method for rearranging work rolls in rolling according to item 1 or 2 above, characterized in that the cumulative values of the products of are adjusted to be approximately equal [Function] The following describes the effects brought about by the method of the present invention according to the drawings.

FIG. 1 is an explanatory diagram 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 a flat upper reinforcing roll and a lower reinforcing roll, respectively.

In Fig. 1, the upper and lower work rolls can move 8 times relative to the roll axis direction indicated by the mark, but no matter which position they move 8 times, the distance between the work roll and the reinforcing roll is the curve m shown in Fig. 2. An uneven pressure distribution occurs in the roll axis direction as shown in the figure. Since the integral value of this pressure distribution is equal to the rolling reaction force, as mentioned above, if the reinforcing roll and the work rolls facing each other are given the same uneven initial crown, the uniformity shown by the straight line n in FIG. This results in a pressure distribution.

In FIG. 2, the range where the curve m is higher than the straight line n is the range where the wear and transfer fatigue of the work roll and the reinforcing roll are greater than in other parts, and the service life is shortened.

Japan Railway 914 Association edition' Iron m Handbook III (1)
As shown in JP 262 (issued 55, 5, 15), work rolls are rearranged between 3000 and 5000 t,
The amount of roll grinding is determined mainly by improving heat cracks and reduction in roll hardness. On the other hand, since the reinforcing roll has a long roll change cycle, the amount of grinding is determined mainly by the amount of fatigue layer removed in order to prevent spalling. Therefore, the work rolls are replaced within a period in which transfer fatigue is not a problem, and the fatigue layer is ground to a level that is not a problem, so there is no effect of the local increase in inter-roll surface pressure, but the reinforcing rolls The amount of grinding of the roll is greatly influenced by the state of occurrence of this fatigue layer, which not only determines the life of the roll, but also
If the amount of grinding is not sufficient, there is a high risk of causing spalling. According to the test results of the present inventors, this fatigue layer is proportional to the cumulative rolling length as shown in FIG. 3 in rolling where the rolling load is approximately constant. Furthermore, when the rolling load varies, the fatigue layer is proportional to the cumulative value of the product of the load and rolling length for each rolling pass. Therefore, in order to extend the life of the reinforcing rolls and to reduce the risk of spalling, the method of the present invention rearranges the upper and lower working rolls that are in contact with the upper and lower reinforcing rolls vertically or horizontally, so that the roll surface between the rolls is By performing rolling with the pressure distribution alternately reversed between left and right after and before recombination, transfer fatigue of the reinforcing rolls is dispersed in the lengthwise direction of the roll body, thereby extending the life of the reinforcing rolls.

[Example] Plate thickness 4.5 to 40 mm, plate width 1.5 to 5 m, plate length 10
~ 60m steel plate per reinforcing roll replacement period is approximately 10
Table 1 shows the results when rolled at 10,000 tons along with comparative examples.

In Examples 1 to 3 of the method of the present invention and the conventional example, initial crowns with uneven shapes are provided on the upper and lower work rolls, respectively.
The roll curve at that time was shaped as expressed by the following equation (1).

f (X) = y (X) −ys (X) 'y4
(x) (+) However, y4(X) =X' 1.6X
(3) (Here, the unit of X is m) Further, the initial crown of the reinforcing roll was not particularly provided, and a flat roll was used.

The rolling in this example was carried out using 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 compared to the conventional example conducted under almost the same rolling conditions, and the roll was almost the same as before use. It can be seen that a roll grinding amount of about % is sufficient to return the roll hardness to the value.

Table [Effects of the Invention] According to the present invention, an initial crown with an uneven shape between the grooves is provided to each of the upper work roll and the lower work roll so as to be point symmetrical to each other, and the above-mentioned upper and lower work rolls are moved relative to each other in the axial direction. In the rolling mill that controls the crown of the rolled material rolled by the upper and lower work rolls, the roll surface pressure distribution between the upper and lower work rolls that are in mutual contact with the upper and lower reinforcing rolls is as follows:
By rearranging the rolls to the same or other upper and lower work rolls so that the left and right sides are opposite after and before roll rearrangement,
It solves the problem of reducing the lifespan of the upper and lower reinforcing rolls and causing roll accidents called spalling, and has industrial effects such as improving rolling productivity, improving rolling quality, and omitting finishing processes such as straightening. It's a huge amount.

[Brief Description of the Drawings] Fig. 1 is an explanatory diagram regarding the initial crown of the work roll according to the present invention, Fig. 2 is a diagram showing the roll surface pressure distribution acting between the work roll and the reinforcing roll, and Fig. 3 is a diagram showing the roll surface pressure distribution acting between the work roll and the reinforcing roll. FIG. 3 is a diagram showing the relationship between cumulative rolling extension and fatigue layer depth in rolling where the rolling load is approximately constant. 1... Rolled material, 2... Upper work roll, 3
...Lower work roll, 4.Top reinforcement roll, 5.
・Bottom reinforcement roll. Fig. Fig. Cumulative pressure extension (-1

Claims (1)

[Scope of Claims] 1. An initial crown of unevenness is provided to each of the upper work roll and the lower work roll so as to be point symmetrical to each other, and the above-mentioned upper and lower In a rolling mill in which the work rolls are moved relative to each other in the axial direction to control the crown of the rolled material rolled by the upper and lower work rolls, when replacing the upper and lower work rolls, the combination of the upper and lower work rolls after recombination is different from that before recombination. Method 2 of rearranging work rolls in rolling, characterized by the combination of upper and lower work rolls and performing the rolling in the opposite direction In a rolling mill, the upper and lower work rolls are moved relative to each other in the axial direction according to changes in rolling conditions such as the width, thickness, and rolling load of the material to control the crown of the material to be rolled that is rolled by the upper and lower work rolls. Method 3 for rearranging work rolls in rolling, characterized in that the roll surface pressure distribution between the upper and lower work rolls that are in mutual contact with the upper and lower reinforcing rolls is reversed from left to right after rearranging and before rearranging 3 Within one rearranging period of reinforcing rolls is characterized in that, when the work rolls are rearranged so that the combination of the upper and lower work rolls is the opposite vertically or horizontally to the combination of the upper and lower work rolls before the rearrangement, the cumulative pressure extension in each of the combinations is adjusted to be approximately equal. Method 4 for rearranging work rolls in rolling according to claim 1 or 2. When rearranging work rolls, the combination of upper and lower work rolls is reversed vertically or horizontally from the combination of upper and lower work rolls before rearrangement within one rearrangement period of reinforcing rolls. A method for rearranging work rolls in rolling according to claim 1 or 2, wherein the cumulative value of the product of the load and rolling length for each rolling pass in each of the combinations is adjusted to be substantially equal. Claim characterized in that, when the combination of the upper and lower work rolls is reassembled vertically or horizontally opposite to the combination of the upper and lower work rolls before reassembly, the cumulative pressure extension in each of the combinations is adjusted to be substantially equal. Method 6 of rearranging work rolls in rolling according to 1 or 2. During the life of the reinforcing roll, when rearranging the work rolls, the combination of upper and lower work rolls is reversed vertically or horizontally from the combination of upper and lower work rolls before rearrangement, each of the above The method for rearranging work rolls in rolling according to claim 1 or 2, characterized in that the cumulative value of the product of the load and rolling length for each rolling pass in the combination of is adjusted to be substantially equal.