JPS6114002A - Hot rolling method - Google Patents

Abstract

PURPOSE:To prevent edge build-up and to control crown by dispersing and decreasing the local wear of the part of work rolls where a slab passes in the stage of rolling at the same width. CONSTITUTION:A pair of the work rolls 1' subjected to convergent grinding 4' at the end on one side of each roll body 4 of a hot finishing mill equipped with the axially movable work rolls are stacked above and below by disposing alternately the ends on one side. Both broadside ends of a rolling stock 3 are positioned between the convergently ground areas of the upper and lower work rolls 1' and the stock is rolled. The stock 3 is rolled while the rolls 1' are shifted cyclically in the range where both broadside ends of the rolling stock do not shift from the convergently ground 4' surfaces.

Description

Detailed Description of the Invention (Technical Field) For 4f-1i or 6Hi rolling mills that aim to combine crown control with edge drop control and shape control, this invention aims to prevent local wear of work rolls and edge build-up together with crown control. The development results for achieving this are described below.

(Background Art) In recent years, the demand for improving the accuracy of plate thickness in the width direction of rolling mills has come to attract attention as a means of improving yield.

(Prior art and its problems) Various crown control methods have been proposed to improve the accuracy of plate thickness in the width direction.

Among these, the trapezoidal roll rolling method disclosed in Japanese Patent Publication No. 56-20081, for example, is effective because edge drop can be improved by changing the geometry of the work rolls.

In this case, the work roll shift method disclosed in Japanese Patent Publication No. 53-151552 is effective and hard for crown control because the crown control effect is reduced by changing the plate width.

In general, as the number of rolls rolled with the same width increases during hot finish rolling, the plateway portion 2 of the work roll 1 wears more at the side portions 2b than the center portion 2a, as shown in FIG. As shown in Figure 2, there is an abnormal protrusion p at the width end of the rolled material 3,
This results in a cross-sectional profile with p' (called edge buildup). It is clear that such edge build-up is the biggest impediment to controlling the crown and performing roll chance-free rolling (that is, rolling that allows width return), and in this respect, using the above-mentioned single trapezoidal roll The situation is no different with the crown control method.

(Objective of the Invention) Therefore, the object of the present invention is to enable crown control that eliminates the cause of obstruction to edge build-up and, ultimately, roll chance-free rolling due to uneven wear in the plateway portion 2 as described above. .

(Start of Idea) As shown in FIG. 3(a), the inventors used a pair of so-called single trapezoidal rolls in which one end of the roll cylinder 4 was tapered and ground 4' as a work roll 1'. The width edges of the rolled material 3 are tapered and ground by stacking them one above the other in an alternating arrangement.
It has been found that when crown control is performed by positioning the stand in the region, there is an effective EL value range determined from the shape limit of the plate between the stands, as shown in FIG. - Tapered grinding area 4 at the width end of the rolled material 3
The grinding area 4' at the width end, with the relief EH for ' being constant
The distance to the boundary was calculated using EL.

If this EL value exceeds the effective EL range by shifting the work roll to increase it, it will exceed the plate shape limit on the exit side and rolling will become impossible, while if the opposite shift limit is exceeded, the crown control ability will be lost.

Therefore, we conducted a study focusing on this effective EL range, and by shifting the work roll 1' within the effective EL range regarding the light range of edge build-up, we developed the hot rolling method of the present invention that achieves both crown control and roll chance-free rolling. This method has been established.

(Structure of the Invention) In this invention i, in a hot finishing rolling mill in which the work rolls are movable in the axial direction, a pair of work rolls whose one end of the roll body is tapered and ground are When rolling is performed by placing the upper and lower work rolls in an alternating arrangement between the respective tapered grinding areas, the work rolls are shifted cyclically to the extent that both width ends of the material to be rolled do not come off the tapered grinding surface. This hot rolling method is characterized by preventing build-up and controlling crown.

The present invention is useful when applied to hot rolling methods, particularly hot thin plate rolling.

Now, an example in which this invention is applied to a 4Hi rolling mill will be explained. Figure 4 is an example when the EL value shown in Figure 3 is increased to the maximum (a value that does not exceed the shape limit on the exit side),
The 5-th power diagram illustrates the limit shift position of the work roll 1' in which the same <EL value is reduced to the minimum (the limit where the crown control ability remains). FIG. 5 is a backup roll.

Work roll 1 within the effective EL range from Figure 4 to Figure M5.
Even if the number of rolled rolls of the same width increases as ' is shifted cyclically, local wear 2b' in the case of constant E as shown in FIG. 6 in the boardwalk section 2' is shown in FIG.
As shown by ``, it becomes possible to disperse the particles in the axial direction 1' of the work roll 1'.

(Example) JIS standard SP HC2, Onmx 1040aun
FIG. 8 shows an example of a change in the cross-sectional profile of the plate on the rolling exit side when the plate is continuously rolled using a single trapezoidal roll rolling method with a constant width of EL=200111111.

There is no abnormality as before until rolling 10 rolls 1, but the 20 roll edge build-up p, p' becomes noticeable and up to 20μ
When the diameter reached φ, further rolling of the same width became impossible.

FIG. 9 shows changes in the cross-sectional profile of the plate due to continuous rolling similar to the comparative example in which cyclic shifts were performed every 20n+m/2 in accordance with the present invention in the range of EL from 200mm to 100mm. Even after rolling 46 rolls of the same width, almost no edge build-up p or p' was observed.

(Effect of the invention) With this rolling method, the local wear of the work roll can be dispersed and reduced during rolling of the same width, so that the round roll can be sufficiently reduced.
(Since the niche drop improvement effect is effectively maintained, it is possible to achieve both roll chance-free rolling and crown control, which were previously difficult.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the roll wear situation. Figure 2 is an explanatory diagram of the edge build-up profile. Figure 3 (a) is a sectional view showing the rolling status with a single trapezoidal roll. Figure 3 (b) is the effective EL. This is a graph showing the range. Figure 4 shows EI, an explanatory diagram of the rolling situation at the maximum, and Figure 5 shows EI.
, Fig. 6 and Fig. 7 are comparison diagrams of examples of roll wear, Fig. 8 is a plate profile graph on the exit side of the rolling mill according to the conventional example, and Fig. 9 is the present invention. This is a plate profile graph on the exit side of the rolling mill. Patent Applicant: Kawasaki Steel Corporation Figure 1 Figure 2 Figure 3 Bad Width W 葎fn> - Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 1-11-1 Width-11-11 Figure 9 Procedures Amendment (method) % formula % 1. Indication of the case 1982 Patent Application No. 374□78 2. Name of the invention Hot rolling method 3. Person making the amendment Relationship with the case Patent issue Kojin (1251 Kawasaki Steel Co., Ltd. 4, Contents of the 7% amendment by the agent (as attached) Figure 3 in the drawings is corrected as shown in the attached correction diagram. Figure 3 Width W (mm) -

Claims (1)

[Claims] 1. In a hot finishing rolling mill in which the work rolls are movable in the axial direction, a pair of work rolls whose one end of the roll body is tapered and ground are rotated alternately at one end. Lay them one above the other in the arrangement,
When rolling is performed by positioning both width ends of the material between the tapered grinding areas of the upper and lower work rolls according to the width of the material to be rolled, the size of both width ends of the material to be rolled is adjusted within a range that does not fall outside the tapered grinding surface. A hot rolling method characterized by shifting work rolls in clicks to prevent edge build-up and perform crown control.