JPS608883Y2 - Guide to prevent bending when cutting slabs in the longitudinal direction - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a guide installed on the exit side of a stand to prevent marks when cutting grooves in a hot slab by rolling using a roll having an annular projection.

A method is conventionally known in which a groove is rolled into a hot slab using a roll having an annular protrusion having a wedge-shaped cross section, and the width of the slab is divided and cut along the groove.

In this method, the groove is generally deepened gradually over three to five passes.

FIG. 1 shows the principle of this method.

11 and 11' are hot slabs, 12 and 12' are cutting rolls, and 13 and 13' are annular protrusions installed on the rolls.

If a reduction of 0.7 to 0.8 times the remaining thickness of the groove is applied, the slab will be cut and separated, and if the reduction is less than that, the slab will not be cut and separated, but the remaining thickness of the groove will only become smaller.

If the slab is cut with a large residual thickness at the cut portion, the total number of passes from the start of re-rolling to cutting can be reduced, but the billow bending during cutting will increase.

If the remaining thickness of the cut portion is small, the amount of bending can be reduced to a certain extent, but this causes problems such as an increase in the total number of passes and the need for precision in setting to maintain a reduction above the cutting limit.

Figure 2 shows the shape of the slab cut pieces when the slab is divided into three parts.

21 shows the center cut piece, and 22 and 23 show the both side cut pieces.

Generally, the cut portions on both sides have a bend as shown at 24 and 25, so it is desirable to keep the amount of bend as small as possible from the viewpoint of handling after cutting and space in the heating furnace.

To reduce bending, the method of adjusting the pass schedule to reduce the residual thickness before cutting as described above is effective to some extent, but it has the disadvantage of increasing the number of passes.

The present invention relates to a restraining guide provided on the exit side of the stand in order to solve this problem.

In the following, a plate-shaped guide will be mainly explained as an example, and then a hard roll type guide will be explained.

FIG. 3 shows a case without an outlet guide. In this case, the hot slab 31 bends during cutting, so that the cut pieces on both sides protrude in the width direction of the slab at the outlet side of the stand.

FIG. 4 shows that the exit guide is installed so as to restrain the overhang caused by cutting to reduce the sharpness when cutting the slab.

41 is a hot slab, 42 is a cutting roll, 43 is an entry guide, and 44 is an exit guide.

The entrance guide 43 serves to prevent the slab from meandering, and in particular does not receive any reaction force from the slab.

The exit guide 44 naturally receives a reaction force from the slab because it plays the role of suppressing overhang when cutting the slab.

Therefore, it is necessary to have a structure that can withstand this reaction force.

This point is different from a normal meandering prevention guide.

The force Fc applied to the tip opening restraint guide during cutting is Fa=α・F9 (
1) However, F8 is expressed as a cutting path stand reaction force.

The coefficient α changes depending on the slab width, slab thickness, slab length, and pass schedule, and according to experiments conducted by the present inventors, it is approximately 0.1<α<1.0.

The position, length, and shape of the guide shown in FIG. 5 also affect the bending prevention effect.

In FIG. 5, P indicates the corner of the tip of the slab, and the broken line a is the locus of point P on the cutting path when there is no exit guide.

Further, g is the exit side guide, and angle θ is the angle that the guide makes with respect to the traveling direction.

Since the force for reducing bending does not act on the slab until the tip of the slab begins to come into contact with the guide in the cutting path, it is difficult to suppress the bending in the vicinity of the tip of the slab.

For this reason, it is desirable to make the distance 11 from the roll to the outlet guide entrance as small as possible, and in some cases it may be possible to make the entrance side continuous with the ID.

Practical range is 0<11<0.3L
......(2) (L is slab length) It is expressed as follows.

Additionally, the distance 1° from the roll to the exit guide should ideally be about the length of the slab in order to minimize bending, but the practical range is 1□>0.6L.
......(3) (L is slab length) It can be expressed as follows.

Also, the guide does not necessarily have to be parallel to the direction of travel; depending on the desired shape of the cut piece, it may be installed at an open angle to the direction of travel as shown in Figure 5, or conversely at a closed angle. is possible.

The guide shape also does not have to be straight, and may be slightly curved.

FIG. 6 shows the effect of reducing bending of the exit guide when a three-part cutting experiment was conducted using a hot steel piece.

The bending measurement points are as shown in a, and the bending amount δ per total length (approximately 30 −) is taken as a representative value.

The graph b represents the relationship between the exit guide setting width and the bending amount δ of the three-part cut piece at both ends.

The horizontal axis is expressed as the difference between the exit guide setting width and the slab width before cutting.

In the figure, the dot with a fragrant stone indicates the amount of bending δ when there is no guide on the exit side, which is about 11 mm.

The bending was reduced to about 2rrvn by the exit guide, and this experiment also confirmed the effectiveness of the exit guide restraint.

Also, the guide reaction force at this time was 4 tons, and the mill reaction force was 16 tons, which was about 174.

Figure 7 shows a method for preventing bending using a vertical roll guide.
81 is the slab to be cut, 82 is a cutting roll, 83 is a vertical roll type entry guide, 84, 84' and 84' are vertical roll type exit guides, and 85 is the front end corner of the slab.

Further, the distance 1 is the roll interval in the slab moving direction, and d is the vertical roll diameter.

If the roll interval becomes too wide relative to the roll diameter (1)
As shown in the figure, a part of the slab tip corner collides with the vertical roll.

This is due to slab cutting bending that occurs while the slab moves by a vertical roll spacing of 1.

If such a collision occurs, the smooth movement of the slab will be hindered, and the rolls will be damaged, the annular protrusion of the cutting roll will be damaged, and the shape of the cut pieces will deteriorate. Therefore, the rolls must be arranged to meet the following conditions. be.

In the case of a plate-shaped guide, the point of application of the force received from the slab moves together with the slab, but the guide as a whole only needs to resist the slab reaction force.

On the other hand, in the case of a vertical roll guide, the force may be concentrated on each roll, so the yield strength of each roll alone is αF.

It is necessary to take (0, α<1.0).

Throughout the above description, the entrance and exit sides have been illustrated as being fixed, but if the rolling stand is of the reverse type, the above conditions must be satisfied on both longitudinal sides of the stand.

[Brief explanation of drawings]

Figure 1 shows the principle of cutting the slab in the longitudinal direction, A is a front view, the opening is a side view, Figure 2 is a cut shape diagram showing how the slab is cut into three parts, and Figure 3 is a diagram showing the cutting shape of the slab. Fig. 4 is a side view showing the cutting state when there is no exit guide, Fig. 4 is a side view showing the cutting state when guides are provided on the entry and exit sides, and Fig. 5 is the position, length, and position of the exit guide. FIG. 6 is an explanatory diagram showing the influence of shape on preventing bending. FIG. 6 is a diagram for explaining the effect of reducing bending by the exit side guide, where a shows the bending measurement point and b shows the relationship between the guide interval and the bending amount. FIG. 7 is a side view showing another example of the present invention. 11.11'・・・Hot slab, 12.12'・
... Cutting roll, 13, 13' ... Annular projection, 21 ... Center cut piece, 22, 23 ...
... Cut piece on both sides, 24.25 ... Curve amount of cut piece on both sides, 31, 41.81 ... Cut slab, 32, 42, 82 ... Finely cut roll, 33. 43...
Input side guide, 44...Output side guide, 83...
...Vertical roll type entrance guide, 84.84'84''・
... Vertical roll type exit guide, 85 ... Part of the slab tip corner.

Claims (1)

[Claims for Utility Model Registration] 1. A longitudinal cutting device for a slab that rolls and shapes a cutting groove with a roll having an annular protrusion for width-dividing a hot wide slab and cuts the slab along the bottom of the cutting groove. , on the exit side of the roll having the annular protrusion, the end closer to the roll is located within 0.3@ of the slab length from the roll axis, and the end farther from the roll is located within the roll axis. The length is at least O0 of the length of the slab, and the reaction force in the width direction of the slab is 0.1 to 1.0 @ of the reaction force when cutting the slab of the rolling mill including the roll having the annular protrusion. A guide for preventing bending during longitudinal cutting of slabs, which is configured to resist force. 2. The guide for preventing bending in longitudinal cutting of slabs according to claim 1, wherein the guide is a row of hard rolls with an axial center spacing of not more than three times the roll diameter.