JPH0330441B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a technology for width reduction of hot slabs, and in particular, a technology for width reduction of hot slabs using a press that can maintain the slab planar shape well without impairing high productivity. Concerning a method of significant reduction.

Initially, hot strip rolling involved reheating the slab material in a heating furnace and then rolling it using continuous casting equipment. It is a well-known fact that the process of directly manufacturing slabs has become mainstream. However, in recent years, in order to further improve the efficiency of energy and manufacturing processes, technology has been introduced to integrate the casting width in continuous casting and to significantly reduce the slab as a technology to synchronize continuous casting and hot strip mills. has been considered.

(Prior Art) Among these methods, as a method for reducing the width of a slab, VH rolling is usually performed in which edging (V) rolling using vertical rolls and horizontal (H) rolling are repeated.

First, when a slab is subjected to V-rolling, dogbone deformation in which the plate thickness at the width end of the slab swells, and fishtail deformation in which the width end of the slab protrudes in the longitudinal direction of the slab at the front and rear ends of the slab are likely to occur. If a slab having this dogbone deformation is subsequently subjected to H-rolling, the width will significantly widen, canceling out the amount of width reduction by V-rolling, and the processing energy required for V-rolling will be wasted. Further, when the width reduction amount is large, multiple bath rolling is required, which impedes production efficiency and causes large energy loss.Furthermore, the feed tail increases approximately in proportion to the full width reduction amount, resulting in a decrease in yield.
Furthermore, in V-H rolling, a large tensile stress is generated at the center of the sheet width during H rolling, so there is a risk that internal defects such as cracks and surface defects may occur.

As a width reduction method that aims to eliminate these drawbacks, there is a wide reduction technique using a continuous press.
When width reduction is performed using a press using this method, the cross section of the slab changes uniformly, and a large amount of width reduction does not result in significant dogbone deformation. The amount of width spread is also small. However, if the width reduction press is performed continuously from the front end to the rear end, a relatively large tongue (tongue shape) is produced at the rear end of the slab, which has the disadvantage of causing a decrease in yield.

(Object of the Invention) The present invention solves the drawbacks of such a large reduction technique using a continuous press, and provides a hot slab that can significantly reduce the slab planar shape, especially the formation of tongues, without impairing high productivity. The purpose of this invention is to provide a method for significantly reducing the pressure by using a press.

(Start of idea) To achieve this objective, the present inventors analyzed and studied the causes of tongue formation in the above-mentioned large reduction method, and found that when continuous width reduction press is performed from the front end of the slab, We have discovered the fact that tongue deformation progresses before reaching a certain length.
As a result of further research into ways to prevent this tongue deformation, we found that the anvil shape of the width reduction press,
In particular, it has been discovered that tongue deformation can be effectively prevented by making the shape of the rolling surface for rolling down the width of the rear end of the slab a specific shape and adopting a specific process using this shape, and the present invention. was completed.

(Structure of the Invention) That is, the gist of the present invention is that the hot slab is heated using a pair of anvils that have inclined portions on the entry and exit sides in the direction of progress of the hot slab and a parallel portion in the middle on the same horizontal plane. When pressing a slab to a predetermined width, in the steady deformation region including the tip of the slab, the width reduction is performed continuously using the entrance inclined part and the parallel part of the anvil, and the width reduction is applied to the non-conforming part of the rear end of the slab. When the steady deformation region is reached, the continuous width reduction is interrupted, the slab is further advanced, and the rear end of the slab is preformed using the exit slope of the anvil, and then the slab is A method for width reduction of a hot slab using a press, characterized in that the hot slab is moved back to the width reduction interruption position, and then the unsteady deformation area is subjected to width reduction in the same manner as the steady deformation area.

The present invention will be explained in detail below.

Continuous width reduction pressing on hot slabs is performed by basic operations as shown in FIG. That is, the rolled surfaces of the pair of anvils 3 have an inclined part 1 on the entry side in the traveling direction R of the hot slab 4, and parallel parts 2 on the intermediate and exit sides following this, and these anvils 3
oscillates periodically under the width reduction amount ΔW (amplitude 2a)
while continuously (or intermittently) feeding a slab 4 with an entrance board width W _s into the gap, reducing the width of the slab to obtain a slab with an exit board width W _f ,
At that time, one cycle of this continuous width reduction press consists of (a) slab reduction, (b) anvil detachment (amplitude 2a), slab advancement, and (c) slab reduction (W _p :
It consists of the operation of the pressure reduction area).

As described above, when the width of the slab 4 is reduced by such a basic operation, a relatively large tongue is generated at the rear end of the slab.

By the way, it has been found that such tongue deformation progresses as shown in FIG. The figure shows the deformation status of the rear end of the slab over time when the anvil 3 with the anvil angle θ = 12° on the slope is operated under the conditions of amplitude 2a = 60 mm and width reduction ΔW = 300 mm. It is. As you can see from the figure, the rear end of the slab is at the anvil 3.
At the stage near the rear end of the entrance side slope of the slab 4, the rear end of the slab 4 is in an unprocessed state and no tongue deformation has occurred. Tongue deformation begins to occur during width reduction at a stage when the slab advances forward by approximately half the width of the slab width from the rear end of the slope, and as the slab advances further, the tongue deformation gradually grows.

In consideration of the production process of the tongue shape, the present invention makes the anvil shape a specific shape and utilizes this shape. This point will be explained below.

FIG. 4 shows an example of an anvil shape according to the present invention.
It has a rolling surface with an inclined part AB on the entry side, a parallel part BC in the middle, and an inclined part CD on the exit side. The inlet inclined part AB has an inclination angle θ, and the outlet inclined part AB has an inclination angle θ.
CD has an inclination angle θ'. The entry side inclined part AB and the parallel part BC are rolling surfaces for forming a steady deformation area including the tip of the slab 4, and the exit side inclined part CD is a rolling surface for forming a steady deformation area including the tip of the slab 4. This is the rolled surface for preforming.

The process of reducing the width of a slab using a press device having such an anvil configuration is as follows: First, a press that vibrates periodically according to the basic operation described above utilizes the reduction surfaces of the entry side inclined part AB and parallel part BC. , width reduction is started from the tip of the slab 4.

Then, when the width reduction reaches the unsteady deformation region of the slab rear end, the slab rear end treatment is performed. In this process, for example, referring to FIG. 5, the above-mentioned width reduction is performed until the unreduced finished area l at the rear end of the slab reaches about half of the slab width;
(a) Next, the anvil 3 is opened once beyond the initial width of the slab, and the slab 4 is further advanced (arrow R in the figure).
(direction), and the rear end of the slab moves to a position where it contacts the outlet inclined portion 6 (b). In this state, when the anvil 3 is rolled down (arrow) using the exit inclined portion 6, the rear end portion is deformed into a fishtail shape and preforming is performed (c).

The reduction amount d of this slab rear end preforming differs depending on the width reduction amount ΔW, etc., but generally d=0.3ΔW
It is best to set it in the range of ~ΔW. However, to be more precise, the amount of tongue at the rear end of the slab that occurs when the entire length of the slab is simply pressed down, and the amount of tongue at the rear end of the slab that occurs when the rear end of the slab is pressed at an angle according to the present invention (pressing using the exit side slope part of the anvil) Determine so that the resulting fishtails cancel out. That is, the original slab width W _s , the slab width after pressing W _p , the slab temperature T,
From the anvil inclination angles θ and θ′, the reduction amount d is d=f
(W _s , W _p , T, θ, θ′, …). Furthermore, when rolling this slab using a continuous hot rolling mill afterwards, it is recommended to take into consideration the rough rolling conditions and decide so that the amount of crop cut-off in the sheet bar after rough rolling is minimized. Of course, this is true.

After performing the preforming (c) in this way, the anvil 3 is opened again to a width greater than the initial width of the slab, and the slab 4 is once retreated (in the direction of arrow R') (d), and then, while the slab 4 is moved forward, Similar to width reduction (a) before processing the rear end of the slab, use a continuous width reduction press until the rear end of the slab is at the anvil 3.
Do this until you get out of the gap. Since the slab rear end treatment is performed in this manner, the amount of tongue produced at the rear end portion can be reduced.

Next, an example of a continuous width reduction press device according to the present invention is shown in FIG. In the figure, the anvil 3 is vibrated by a hydraulic cylinder 9 via an anvil fixing block 8 slidably provided in the window of the housing 10, and the anvil shape is as shown in FIG. (The advancing direction of the slab 4 is indicated by an arrow R in the figure.). Note that 7 is a pinch roller for conveying the slab.

Next, the operation of the present invention will be explained in detail, including slab conveyance control.

In FIG. 7, a slab 4 having an entry side plate width W _s is conveyed in the direction of arrow R in the figure, and when the slab detector 21 detects the tip of the slab, the pinch roller 20
While tracking the slab by the pulse generator 22 connected to this pinch roller, the inclined part AB and parallel part BC of the anvil 3 are
Use to reduce the specified width from the slab tip (plate width
W _p ), forming a steady deformation region.

The rear end of the slab 4 is connected to the slab detector 21'.
From the moment it is detected by the pinch roller 2
0' is lowered, and the rear end of the slab 4 is tracked by the pulse generator 22' connected to this pinch roller, and the rear end position 4a of the slab is moved from point B to position l as shown by the two-dot chain line in the figure. At that point, that is, when the unsteady deformation region is reached, the anvil 3 is once expanded to be larger than the initial width _Ws of the slab, and then the pinch roller 20' is used to spread the slab 4 until the rear end of the slab passes point C. It is further advanced by L, and the anvil 3 is operated to perform a preforming reduction amount d. Note that the amount of movement for preforming the rear end of the slab may be set to L+x, and in that case, the inclination angle θ' of the exit side inclined part CD of the anvil 3,
The rolling stop position of the anvil 3 can be determined from x and the rolling amount d.

After that, the anvil 3 is again made wider than the initial width W _s of the slab, the slab 4 is once retreated and returned to the original position indicated by the two-dot chain line, and then the same predetermined width reduction as before preforming (plate width W _p ) is made. This is done until the rear end 4a of the slab passes between the anvils 3.

(Example) Using the continuous width reduction press shown in Figure 6, a slab with a width of 1,500 mm, a thickness of 220 mm, and a length of 12,000 mm was produced at an anvil angle of θ = 12° and an amplitude of 2a of θ′ = 20°. =10mm,
Under the condition of a vibration frequency of 2πrad/sec, a width reduction of ΔW = 300 mm was performed continuously from the tip to the stationary part.
When approximately 800 mm of unrolled area remained, the anvil was opened, the slab was moved using a pinch roller so that the rear end of the slab was in contact with the exit slope of the anvil, and the rear end of the slab was then preformed. In addition, the preforming amount d
varies depending on the width reduction amount ΔW, but in this embodiment, d/2=ΔW/2=150 mm as shown in FIG.

When the preforming was completed, the slab 4 was once retreated, and then width reduction pressing (width reduction amount ΔW = 300 mm) was continuously performed at the entrance inclined part and parallel part of the anvil. FIG. 9 shows the planar shape of the rear end of the slab after width reduction (rear end preforming + continuous press).

On the other hand, as a conventional method, when the width of the slab is uniformly reduced from the front end to the rear end, that is, without special slab rear end treatment as in this embodiment, the width is reduced continuously.
The shape of the rear end of the slab after width reduction was the shape shown in FIG. 9 ("continuous press").

As can be seen by comparing the two in Figure 9, in the case of the present invention, the crop is very short, the formation of a tongue is minimal, and the shape of the slab rear end is good, whereas in the case of the conventional In the case of the method, the crop is long and the rear end shape has a significant tongue formation.

(Effects of the Invention) As detailed above, according to the present invention, while maintaining the high productivity of the conventional large reduction technology using a continuous press, the planar shape of the slab, especially the tongue formation at the rear end of the slab, can be improved. It is possible to obtain a product with a significantly reduced planar shape and a very good planar shape, and it is possible to significantly improve the yield.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the basic operation of a continuous width reduction press, Figure 2 A to C are explanatory diagrams showing the basic operation of Figure 1 over time, and Figure 3 is tongue deformation at the rear end of the slab. FIG. 4 is a diagram illustrating an example of an anvil shape according to the present invention, and FIG. 5 is a diagram illustrating a situation in which an unsteady deformation region at the rear end of a slab is width-reduced by an anvil according to the present invention. , FIG. 6 is a side view showing an example of a continuous width reduction press device according to the present invention, and FIG.
The figure is a diagram explaining the operation of the width reduction method of the present invention using the apparatus shown in Figure 6, Figure 8 is a diagram showing the shape of the rear end of the slab after preforming in the present invention, and Figure 9 is a diagram showing the width FIG. 3 is a diagram showing the shape of the rear end of the slab after rolling, where "rear end preforming + continuous press" is according to the present invention, and "continuous press" is according to the conventional method. 1...Inlet inclined part, 2...Parallel part, 3...Anvil, 4...Slab, 6...Outlet inclined part, 7...Pinch roller, 8...Anvil fixing block, 9...
Hydraulic cylinder, 10... Housing, 20, 2
0'... Pinch roller, 21, 21'... Slab detector, 22, 22'... Pulse generator.

Claims (1)

[Claims] 1. When pressing the hot slab to a predetermined width using a pair of anvils that have sloped parts on the entry and exit sides in the direction of travel of the hot slab and a parallel part in the middle on the same horizontal plane, including the tip of the slab In the steady deformation region, the width reduction is performed continuously using the entrance inclined part and parallel part of the anvil, and when the width reduction reaches the unsteady deformation area at the rear end of the slab, the continuous width reduction is performed. After the slab is further advanced and the rear end of the slab is preformed using the exit slope of the anvil, the slab is once retreated to the width reduction interruption position, and then the unsteady A method for width reduction of a hot slab using a press, characterized in that width reduction is performed on a deformed region in the same manner as in the steady deformation region.