JPH07108307A - Method for adjusting mill rigidity in rolling mill - Google Patents

Abstract

PURPOSE:To provide a method for adjusting the mill rigidity of a rolling mill with which the difference between right and left mill rigidities is eliminated greatly easily and precisely without requiring the modification of a device and lateral symmetry is not changed even by the change of rolling conditions. CONSTITUTION:The mill rigidities on the driving side PS and working side WS of a rolling mill are measured by a kiss roll locking test and, between at least a pair of rolls which are mutually brought into contact, the contact length L from the middle part O in the length direction to the end part of the roll on the larger side is reduced on the side of the larger measured value. In addition to that, the contact length L' from the middle part O in the length direction of the roll to the end part of the roll on the smaller side may be increased on the side of the smaller measured value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention generally relates to left and right (driving side and working side) mill rigidity of a rolling roll in order to prevent wedges, bending, meandering, etc. in plate rolling of steel and non-ferrous metal. The present invention relates to an adjusting method for adjusting the asymmetry of the.

[0002]

2. Description of the Related Art Generally, there are various left and right asymmetrical factors that cause the meandering and bending in strip rolling, but they can be roughly classified into the following four factors. And
By adjusting the left-right asymmetry for each of these factors, it is possible to prevent bending, meandering, and wedges from occurring in the rolled sheet, and to manufacture a high-quality product having a symmetrical sheet thickness distribution in the width direction. (1). Left-right asymmetry of rolling material such as wedges, bends, temperature unevenness, etc. (2). Left-right asymmetry of rolling conditions such as tension, lubrication, strip path, etc. (3). Left-right asymmetry of roll gap setting of rolling mill (4). Left-right asymmetry of mill rigidity characteristics and mill elongation characteristics of rolling mill

According to the research conducted by the inventor, regarding (1) and (2) of the above-mentioned four factors, for example, usual material temperature control, lubrication system maintenance control, and adoption of an appropriate plate path guide device, etc. Thus, the left-right asymmetry can be suppressed to such an extent that it does not cause a problem. To adjust the asymmetry of factor (3) above, a constant load is applied by tightening the kiss roll, and the left and right rolls are pressed down so that the load on the left and right (driving side and working side) of the rolling roll becomes zero. Adjust
A method of setting the left and right rolling positions so as not to cause a difference between the left and right roll gaps during rolling is generally adopted. This method is called "roll gap zero adjustment". This method is effective when the mill elongation and mill rigidity of the rolling mill are bilaterally symmetric, but when they are bilaterally asymmetric, there is a difference in the left and right roll gap opening depending on the value of the load, so the entire load range It is impossible to set the reduction position so that the left and right sides are even. Therefore, in order to prevent the bending and meandering of the plate during plate rolling, it is extremely important to adjust the mill elongation and the mill rigidity of the rolling mill so that they are laterally uniform.

The following two methods have been proposed as methods for adjusting the lateral difference between the mill elongation and the mill rigidity of a rolling mill. One of them is, for example, as disclosed in Japanese Patent Publication No. 60-11570, the relationship between the left and right mill elongations and the load is measured, and the left and right roll gaps are set in accordance with the load during rolling. This is a method of correcting the left-right difference of the mill rigidity by correcting at a ratio according to the ratio of the left-right mill rigidity. The other one is, for example, JP-A-53-83959.
As disclosed in the publication, the relationship between the left and right mill elongation of the rolling mill and the load is measured, and a spring with an appropriate spring constant is installed in the rolling system of the one of the left and right stands, whichever has the greater mill rigidity. This is a method in which the rigidity of the mill is made equal on both sides of the stand.

[0005]

Among the methods for adjusting the left and right mill rigidity, the former is a kind of feedback method in which the load during rolling is measured and the left and right roll gaps are corrected. If it changes, the balance of the left and right roll gaps will be lost and the left and right mill rigidity will inevitably become asymmetric. Also, the latter method does not have such drawbacks, but it requires modification of the roll chock or pressure plate in order to incorporate the spring in the reduction system, and the incorporation of the spring reduces the overall mill rigidity, thus reducing the plate thickness accuracy. Is reduced, and the rigidity of the spring is affected by subtle differences in surface contact with the pressure plate, chock, etc., making it difficult to design and construct the spring. Is very difficult. An object of the present invention is to provide an adjusting method capable of adjusting the left and right mill rigidity differences very easily without modifying the device.

[0006]

One of the methods of adjusting the rigidity of a mill according to the present invention is, in order to achieve the above-mentioned object, a kiss roll tightening test before actual rolling to perform mill elongation on the driving side and working side of the rolling rolls. And, at least one set of rolls that are in contact with each other by measuring the rigidity of the mill, on the side where the measured rigidity value is large, the contact length from the center of the length of the roll to the end of the roll on that side. On the side where the measured rigidity value is small, the contact length from the center of the roll in the length direction to the end of the roll on that side is increased. This method is suitable for a rolling mill equipped with a roll shift mechanism, and is carried out by shifting one or a plurality of rolls from a side having a large mill rigidity value to a side having a small mill rigidity value. When carrying out this method, the rolls may be shifted only on one of the upper side and the lower side, or the rolls may be shifted on both sides. The difference between the two is that in the former case, the roll shift amount is larger than in the latter case. If the left and right difference in mill rigidity does not disappear with one operation, repeat the above operation until the left and right difference in mill rigidity disappears.

In order to achieve the above-mentioned object, another one of the methods for adjusting the mill rigidity according to the present invention is to measure the mill elongation and the mill rigidity of the driving side and working side of the rolling roll by a kiss roll tightening test before actual rolling. Measured, between at least one set of rolls that are in contact with each other, on the side where the mill rigidity value is large, the contact length from the center part in the length direction of the roll to the roll end part on that side is made small. is there. This method is mainly suitable for rolling mills not equipped with a roll shift mechanism.
It is carried out by chamfering one or both ends of the work roll and the reinforcing roll. If the left and right difference in mill rigidity does not disappear after one operation, repeat the above operation until the left and right difference disappears. The cutting of the roll end portion may be performed only on either the upper stage side or the lower stage side, or may be performed on both upper and lower stages.

[0008]

[Function] Factors that control the mill rigidity on each side include, for example, the rigidity of the stand post itself on each side,
The shape and contact state of the pressure plate and chock, the bending of the rolling roll and the contact flat deformation may be considered. As in the method according to the present invention, on the stand side where the mill rigidity is high, by reducing the contact length from the center part of the roll length direction to the roll end part, the contact load distribution between the rolls is closer to the roll center. The roll amount on the side and the flat deformation amount relatively increase, and the difference between the left and right mill rigidity is offset. Further, when the contact length between the rolls on the opposite side is increased, the roll deflection amount and the deformation amount on the side are relatively reduced by the action opposite to the above, and the difference between the left and right mill rigidity is offset. Therefore, the mill rigidity on the drive side and that on the working side are adjusted to be balanced. And, the mill rigidity adjusting method according to the present invention shifts at least one roll in the opposite direction from the side having large mill rigidity, or cuts the end portion of at least one roll into a chamfered shape on the side having large mill rigidity. It is extremely simple to carry out and requires no modification of the device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a mill rigidity adjusting method according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic front view showing a state of a kiss roll tightening test of a rolling mill before rolling, and FIG. 2 changes contact lengths of an intermediate reinforcing roll and an upper reinforcing roll on an upper stage side of the rolling mill of FIG. 1 is a partial front view of the rolling mill of FIG. 1, FIG. 3 is a partial front view of the rolling mill of FIG. 1 in which the contact length between the intermediate reinforcing roll and the lower reinforcing roll is changed, and FIG. A line graph showing the relationship between the load and the tightening amount during the kiss roll tightening test, FIG. 5 is a line graph showing the relationship between the load and the tightening amount after adjusting the rigidity of the left and right mills, and FIG. 6 is rolling in another example. FIG. 7 is a schematic front view showing a state of a kiss roll tightening test of the rolling mill, and FIG. 7 is a schematic front view showing a state in which the contact length between the work roll and the reinforcing roll of the rolling mill of FIG. 6 is changed.

The six-high rolling mill of FIG. 1 has a structure having a roll shift mechanism (not shown). 1,1 'are work rolls, 2,2' are intermediate reinforcing rolls, 3,3 'are upper reinforcing rolls and It is a lower reinforcement roll. In the state in which the kiss roll is tightened before rolling in FIG. 1, the upper intermediate reinforcing roll 2 has a length of 1 L in the working side WS direction, and the lower intermediate reinforcing roll 2 ′.
Are each shifted by 1 L'in the drive side DS direction, and the contact lengths of the rolls 1, 2, 3 from the central portion O in the roll length direction to the drive side DS end portion are L and the central portion O. The contact length of the rolls 1 ', 2', 3'from the end to the working side WS end is L '.

In the kiss roll state of FIG. 1, a tightening operation (not shown) is performed to detect the tightening amount and the reaction force received by the housing (not shown) on each side. taking measurement. The upward arrow group in the figure illustrates the distribution state of the contact load between the rolls. FIG. 4 shows the difference in mill rigidity on each side during the kiss roll tightening test. In this example, drive side D
The mill rigidity of S is higher than that of the working side WS, and the plate rolled in this state has a thick plate thickness at the working side WS
It will meander in the direction of.

In this embodiment, in order to eliminate the left-right asymmetry of the mill rigidity shown in FIG. 4, the upper intermediate roll 2 is further shifted by α (10 mm) from the drive side DS in the opposite direction as shown in FIG. The contact length L between the rolls 3, 2 and 1 from the center O of the rolls to the end of the drive side DS is reduced by α, and as shown in FIG.
0 mm) to further shift in the operation side WS direction to increase the contact distance L ′ from the central portion O of the roll to the operation side WS end by α. As described above, when the roll-to-roll contact length L of the drive side DS is reduced and the roll-to-roll contact length L ′ of the working side WS is increased, the contact load between the rolls is increased as indicated by the upward arrow indicated by the dotted line in the figure. The distribution is closer to the center in DS,
With WS, the rolls move to the side, respectively, while with DS, the amount of roll deflection and flat deformation increases, and with WS, they decrease. Therefore, it is adjusted by offsetting the difference in mill rigidity on both sides. Then, the kiss roll is tightened again and the mill rigidity on both sides is measured. When the result is balanced on each side as shown in FIG. 5, the adjustment of the mill rigidity is completed.

If the mill rigidity of each side is not balanced in the measurement of the mill rigidity again, the intermediate rolls 2 and 2'are shifted in a certain direction according to the result, and a kiss roll tightening test is conducted. Repeat and repeat the same operation until the mill rigidity on both sides becomes equal.

In the adjusting method of this embodiment, since the mill rigidity on both sides of the rolling mill is adjusted only by shifting the rolls, the mill rigidity can be adjusted extremely easily and accurately without any modification of the apparatus. .

In the above-described embodiment, the upper and lower intermediate rolls 2 and 2'are shifted in a certain direction in accordance with the measurement results of the mill rigidity on each side by the kill roll tightening test.
Only one of the intermediate rolls 2 or 2'has approximately 2α
Even if it is shifted to the work side WS, the same operation can be performed. Further, instead of shifting the intermediate rolls 2 and 2 ', the work rolls 1 or 1', the upper reinforcing rolls 3 or the lower reinforcing rolls 3'can be similarly shifted.

FIG. 6 shows a four-high rolling mill not equipped with a roll shift mechanism, and the contact lengths L and L'between the rolls from the central portion O in the length direction to both sides are the same. Figure 6
Kiss roll tightening test is performed in the state of
As a result of measuring the mill rigidity of S and WS, as shown in Fig. 4, WS
Assuming that the DS had a higher mill stiffness than DS, the rolled sheet meanders to WS as in the previous example. In order to eliminate the difference in rigidity between the left and right mills and equalize them, the chamfered cutting portion 30 at the DS end of the upper reinforcing roll 3 is further cut or ground as shown in FIG.
By increasing the width w of 0 by, for example, nα, the rolls 1, 3 from the central portion O in the length direction of the roll to the DS end portion
The contact length L of is reduced by nα.

As described above, when the contact length L of the DS between the rolls 1 and 3 is reduced, the contact load distribution between the rolls in the DS shifts toward the center O, and the amount of flexure or flat deformation of the rolls in the DS is reduced. The relative increase offsets the difference in mill stiffness on both sides, thus adjusting the difference in left and right mill stiffness.

Then, the kiss roll tightening test is conducted again, and as a result, if the left and right mill rigidity differences are equal, the adjustment is completed. If the mill rigidity difference between the left and right is not equal, and if the mill rigidity is still large in DS, cutting or grinding is performed so as to increase the width w of the cutting portion 30 at the end of the roll 3, and the result of the kiss roll tightening test Repeat the same operation until there is no difference in mill rigidity. If the WS mill rigidity is higher than DS, the WS of roll 3
Cutting or grinding is performed to increase the width w ′ of the cutting portion 31 at the end.

According to the method of the embodiment shown in FIGS. 6 and 7, since the mill rigidity is adjusted only by cutting or grinding the end portion of the roll into a chamfered shape, the mill can be remarkably easily modified without requiring any modification. The rigidity can be adjusted. In the example of FIG. 7, only the DS end of the roll 3 is cut into a chamfer, but the DS end of a plurality of rolls may be cut, or the end of another roll 1, 1 ′ or 3 ′ may be cut. Even if cut, the same effect is obtained. Further, the chamfered cutting portions 30 and 31 in the above embodiment are formed by cutting the shoulders of the roll ends in a tapered shape, but it is sufficient if the contact length L or L ′ between the rolls is small. Therefore, it can be carried out by cutting or grinding in a circular arc shape or another shape instead of the tapered shape.

[0020]

The method of adjusting the mill rigidity according to the present invention is as follows.
The mill stiffness can be adjusted extremely easily and accurately without modification of the device. In addition, the symmetry of mill rigidity on both sides does not become unbalanced due to changes in rolling conditions.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a state of a kiss roll tightening test of a rolling mill before rolling.

FIG. 2 is a partial front view showing a state where the contact length between the intermediate reinforcing roll and the upper reinforcing roll on the upper side of the rolling mill of FIG. 1 is changed.

FIG. 3 is a partial front view showing a state where the contact length between the intermediate reinforcing roll and the lower reinforcing roll on the lower side of the rolling mill of FIG. 1 is changed.

FIG. 4 is a line graph showing the relationship between the load and the amount of tightening during a kiss roll tightening test by the rolling mill of FIG.

FIG. 5 is a line graph showing the relationship between the load and the tightening amount after adjusting the rigidity of the left and right mills.

FIG. 6 is a schematic front view showing a state of a kiss roll tightening test of a rolling mill in another example.

7 is a schematic front view showing a state where the contact length between the work roll and the reinforcing roll of the rolling mill of FIG. 6 is changed.

[Explanation of symbols]

1, 1'Work roll 2, 2'Intermediate work roll 3 Upper reinforcement roll 3'Lower reinforcement roll 30, 31 Chamfered cutting part L, L'Roll contact from the center of the length direction of the roll to each side end Length l, l 'Initial shift length of roll α Adjusted length of roll contact part w, w' Width of cutting part at roll end

Claims (2)

[Claims] 1. A kiss roll tightening test before rolling is performed to measure mill elongation and mill rigidity on the driving side and working side of a rolling roll, and the measured rigidity value is large between at least one set of rolls in contact with each other. On the side, the contact length from the center part in the length direction of the roll to the roll end part on the side is reduced, and on the side where the measured rigidity value is small, from the center part in the length direction of the roll to the side. A method for adjusting mill rigidity in a rolling mill, comprising increasing the contact length to the roll end to balance the mill elongation and the mill rigidity on the drive side and the working side. 2. A kiss roll tightening test before actual rolling to measure mill elongation and mill rigidity on the driving side and working side of the rolling roll, and to measure the rigidity value between at least one set of rolls in contact with each other. On the large side, by reducing the contact length from the center of the roll in the length direction to the roll end on that side, it is possible to balance the mill elongation and mill rigidity on the drive side and the working side. A method of adjusting mill rigidity in a rolling mill.