JPS5935283B2 - rolling mill row - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rolling mill train that can properly control the plate crown and obtain a good plate shape when rolling metal materials.
In particular, it relates to a rolling mill row having reinforcing rolls provided with plate crowns and convex crowns with extremely excellent shape controllability.

For example, when rolling metal materials such as steel, a rolling load of ζ9 is applied, which causes deflection of the rolling rolls, flattening the roll surface, and widening the edges of the material to be rolled. The thickness distribution of the plate material in the width direction is that it is thickest at the center (it becomes thinner as it approaches the edges).

Particularly at the edges, the plate thickness decreases rapidly.

This is a plate crown that occurs in the current rolling method, but if such a plate crown is present in the final rolled product, it is undesirable from the viewpoint of product quality and yield.

Further, if the above-mentioned plate crown occurs in the intermediate process of rolling, and if the crown is large, even if an attempt is made to correct it in a subsequent rolling process, the plate material will have a corrugated shape, making the rolling operation difficult.

In such a case, the rolled plate material has a poor thickness distribution shape.

Conventionally, methods for reducing or controlling plate crown in plate rolling include: (1) providing a barrel-shaped crown to the roll body in advance; (2) giving convex or concave deflection to the upper and lower rolls using a hydraulic cylinder, etc.; Method using so-called roll bending action, ■
A method that combines the above methods (1) and (2) is generally put into practical use.

However, these conventional plate crown reduction and control methods have various problems.

In other words, in method (■), the deformation resistance of the rolled material depends on the chemical composition,
Due to factors such as changes due to temperature, etc., variations in sheet width, and changes in the shape of the roll due to thermal expansion and wear of the roll, it is necessary to give the roll an appropriate round in advance for various rolling conditions. is practically impossible.

Furthermore, it is extremely difficult to change and reduce the plate crown without generating plate waves or the like (that is, while maintaining a good plate shape).

In the case of method (2) in which the roll is deflected by a roll bending device to change the plate crown, it is not possible to use a very powerful bending knife in the current rolling mill due to the strength of the roll neck, the life of the bearings, etc.

In addition, the work roll is in contact with the reinforcing roll over almost the entire length of the roll, and the work roll receives extra bending moment from the reinforcing roll outside the width of the rolled material, so the bending effect of the work roll is reduced accordingly. will be done.

For the above-mentioned reasons, the work roll bending effect cannot be obtained up to the center of the car plate width, which appears near the edge of the plate.

Even with the combination method (2), the effect of reducing the plate crown to the extent that it can absorb the variation in the deformation resistance of the rolled material, the variation in the plate width, and the plate crown change due to thermal expansion and wear of the rolls is not brought about, as in the case of the method (2) above. .

The inventors of the present invention solved the problems of the conventional plate crown reduction control method described above, and as a result of repeated research on a rolling mill that can effectively control plate crown reduction during plate rolling. , developed a rolling mill equipped with a unique reinforcing roll with extremely excellent shape control characteristics, and obtained the desired good results.

(Please note that we have already applied for this rolling mill.

) The first rolling mill that can effectively control the plate crown described above is
This will be explained based on the diagram.

This rolling mill has work rolls 2 and 21 below L for rolling a material 1 to be rolled having a width B, and reinforcing rolls 3 and 3' that support the work rolls 2 and 2', respectively. 3' has an effective trunk length L' that is shorter than the effective trunk length of the work rolls 2, 2/, and steps are formed on both outer end sides of this effective trunk length L', and the effective trunk length is The portion L' is provided with a convex crown.

Note that 4 and 4' are roll bending devices for the work rolls 2 and 2'.

(If an appropriate effective trunk length L' is set for the reinforcing rolls 3, 3' by configuring the reinforcing rolls 3, 3', the work rolls 2, 2' can be bent effectively and over a wide range since they have stepped portions at both ends. This allows for effective rounding, shape change, and control ability for various sheet width levels.

Fig. 2 shows the strip width at each level (6 feet) when using the rolling mill shown in Fig. 1 and setting L' = 1257 mm.

It shows how the plate crown reduction and roll bending effect change when rolling 5-foot, 4-foot, and 3-foot materials compared to those in a conventional four-high rolling mill.

The figure shows that the rolling mill equipped with reinforcing rolls with convex crowns can significantly reduce the amount of strip crown compared to the conventional four-high rolling mill, although its effectiveness decreases as the strip width decreases. Moreover, since both ends of the work roll are not constrained, it is clear that a remarkable roll bending effect is produced.

On the other hand, when the above-mentioned rolling mill is put to practical use to obtain rolled products, the relationship between the plate crown and the plate shape becomes a problem.

In normal plate rolling, changing the crown would deteriorate the shape, so the plate crown was thick (it was thought that it could not be changed).

The present inventors conducted further research and experiments to commercialize a rolling mill equipped with reinforcing rolls provided with the above-mentioned convex crowns, and as a result, they were able to effectively control the plate crown and obtain a good plate shape. They discovered a rolling mill row that could produce rolled products of extremely high quality.

In other words, the present invention is characterized in that the number of work rolls is small (both shorter than that of a long work roll in contact with one side), and the work roll is reinforced with a crown on the body part in contact with at least one side of the work roll. In a rolling mill row consisting of rolling mills with rolls, each stand is arranged so that one or more stands can control the plate crown and the final stand can control the shape. It is in.

The present invention will be explained in detail below.

In the present invention, each stand is arranged so that plate crown control is performed in one or more of the upstream and midstream stands of the rolling mill row, and final stand size and shape control is performed.
This is based on the inventors' knowledge that the sheet shape is determined by the rolling conditions of one stand, regardless of the previous history (i.e., in order to obtain a flat product shape, only the final stand is required). It is sufficient to perform shape control, and it is sufficient to perform sufficient plate crown control in the upstream and midstream stands.

This point will be considered in detail below.

FIG. 3 is a chart showing the relationship between changes in the plate crown and changes in the plate shape, and shows actual values obtained through experiments by the inventors.

The horizontal axis of the figure is the difference in elongation in the longitudinal direction between the center and edge of the plate, which was determined from changes in the plate crown assuming that there was no metal flow in the width direction of the plate, and is divided into edge elongation and middle elongation.The vertical axis is calculated from the plate shape. The difference in elasticity is expressed by end elongation and mid-elongation, with end elongation being shown as positive and mid-elongation being shown as negative.

Normally, when the plate crown is changed in order to reduce the plate crown, the plate shape naturally changes accordingly.According to the experiment conducted by the present inventor shown in Kerr Figure 3, changes in the plate crown affect the plate shape. It can be seen that the influence differs depending on the plate thickness and plate width.

That is, when the plate thickness is 3 mm, although there is a difference depending on the plate width B, a change in the plate crown has a relatively large influence on a change in the plate shape.

However, when the plate thickness is 6 mm, the plate crown becomes thicker (even if the plate crown is changed, the resulting change in shape is much smaller than in the case of the three types mentioned above).

This is thought to be because when the plate is thick, there is material flow (metal flow) in the width direction of the plate, which cancels out changes in shape.

Therefore, first of all, if the plate thickness is relatively thick, that is, it is extremely advantageous to control the reduction of the plate crown at the upstream stand and midstream stand in the rolling mill row, considering the effect on shape change. becomes clear.

In addition, the rolling mill having the crowned reinforcing roll used in the present invention has a large roll bending effect as described above. The result will be as shown in Figure 4.

It can be seen from FIG. 4 that the amount of change in roll bending force is proportional to the amount of change in shape, and even if the sheet width B is the same, the shape change with respect to roll bending change is larger when the sheet thickness is thinner.

Furthermore, Figure 5 shows that the plate shape has no relation to its previous history (
This is an explanatory diagram based on experimental results showing that rolling conditions are determined by the rolling conditions of a single stand. This figure shows the shape of a plate obtained by rolling a rolled material under certain rolling conditions.

As is clear from this figure (regardless of whether the plate shape on the inlet side is medium elongation or edge elongation, the outlet side shapes all exhibit edge elongation with approximately the same distribution.

This shows that by changing the rolling conditions (particularly by changing the roll pending force), it is possible to make all the plates on the exit side good and flat, and what is more, it is only necessary to control the shape at the final stand. It turns out.

Therefore, as can be seen from FIGS. 4 and 5 above, if a rolling mill with crowned reinforcing rolls and a roll bending device is installed in the final stand, no matter what the plate shape is on the entry side, It can be seen that complete shape control can be achieved by setting the rolling conditions of this final stand to appropriate values.

From the above, in the present invention, the plate crown is controlled at the upstream stand and midstream stand in a rolling mill row consisting of rolling mills in which reinforcing rolls are crowned, and each stage is controlled so that the final stand has the shape f151Jffllll. All you have to do is arrange the stands.

A rolling mill capable of side-turning the plate crown may be disposed in all of the upstream and midstream stands, or a rolling mill capable of controlling the plate crown may be disposed in any plurality or single stand.

FIG. 6 shows an embodiment of the rolling mill row of the present invention.

In the diagram, one or more stands other than the final stage 11 near stand and the 7th stand have an effective body length shorter than the work roll shown in Figure 1, and a crown is attached to the body. A rolling mill with reinforcement rolls and a work roll bending device is installed.

As a result, the plate crown is changed to a desired crown at the stands other than the final stand, and the roll bending device is operated to correct the shape of the plate so as to make the plate shape good at the final stand.

According to the present invention described above, it is possible to configure a pass schedule that can achieve both crown correction and obtaining a good shape, and its practical value is extremely large.

[Brief explanation of drawings]

Fig. 1 is a diagram showing rolling mills constituting a rolling mill row according to the present invention, and Fig. 2 shows the amount of plate crown reduction and roll bending effect amount for each plate width level when rolling with the rolling mill shown in Fig. 1. Figure 3 is a diagram showing the relationship between plate crown change and plate shape change during plate rolling for each plate width and plate thickness.
Figure 4 is a chart showing the relationship between roll pending force change and shape change for each strip width and thickness in a rolling mill that is not used in the present invention. FIG. 6, which is an explanatory diagram showing shape changes, is a diagram showing an embodiment of a rolling mill row according to the invention. 1... Rolled material, 2, 2'... Work roll, 3, 3
'... Reinforcement roll, 4.4'... Roll venting device.

Claims (1)

[Claims] 1. Rolling constructed by a rolling mill with a small number of work rolls (both shorter than that of a long work roll that contacts one side of the work roll) and a reinforcing roll with a crown on the body that touches at least one side of the work roll. In the machine train, a rolling mill having a reinforcing roll with a crown on the body is arranged in the last stand and one or more stands other than the last stand,
A rolling mill IIO characterized in that a midstream stand controls the plate crown and a final stand controls the plate shape.