JPS58116964A - Cutting method of continuous casting body - Google Patents

Abstract

PURPOSE:To obtain a high-temp. ingot which contains an unsolidified layer without bulging, by pressing down a solidified shell which sandwiches the unsolidified layer remaining in a continuous casting body thereby generating mutual press sticking locally in the inside surface of the solidified shell. CONSTITUTION:In an existing continuous casting machine, a cutter or the like provided at L0 from a mold meniscus 7 is used as it is as in conventional installations, and continuous casting is accomplished. Hydraulic presses 9 are installed at the position of a distance L1 from the meniscus 7 to solidify a continuous casting body 6 under press contact. The high temp. ingot wherein unsolidified steel is confined over the press stuck and solidified area is produced at the casting speed higher than the casting speed in ordinary continuous casting. Thereafter, the ingot is cut by using shearing blades 10 of the presses.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cutting a continuous cast body, and in particular to a continuous cast slab, plume, or billet (hereinafter referred to as The purpose of this invention is to make it possible to continuously and safely obtain slabs (simply referred to as slabs), and to make it advantageous for reducing the unit heat consumption of a heating furnace through direct rolling or hot slab charging.

In recent years, the quality of slabs produced by continuous casting machines has improved significantly (they no longer require surface care, which was previously required).

Therefore, hot-slab charging (hot charge) and direct rolling (direct rolling), which have been attempted in the past for blooming slabs, have been attempted.
trolling).

In practice, a continuous casting machine or even a heating furnace is installed just before the rolling mill, and one piece is directly rolled in the rolling mill.The hot piece is charged into the heating furnace at too - too degrees Celsius, and then rolled. This method is about to be applied to thick plates, cold-rolled thin plates, large steel bars, etc.

However, in this case, there are restrictions on factory power distribution, flexibility in casting and rolling operations is lost, and there is no guarantee that the single-side temperature will necessarily be high or constant, and the existing continuous casting It has drawbacks such as not being able to be adapted to certain machines.

Now, in order to systematize the above-mentioned difficult handling of slabs with current equipment power distribution or minor equipment improvements, it goes without saying that it is necessary to maintain the slabs at a temperature as high as possible or above a certain temperature. .

In this case, in order to effectively utilize the sensible heat and a-heat of the continuous cast body obtained by the existing continuous casting machine, it is effective to use a cast slab, leaving some vertical hardening inside the solidified shell. It is. In fact, by controlling the sequence of secondary cooling that promotes local thinning of the solidified 11iJ shells produced during the continuous casting process, solidified zones that confine unsolidified layers between adjacent solid shells are created intermittently in the longitudinal direction of a piece. Although it was once proposed to form a continuous cast body and cut it, the solidification coefficient of a continuous cast body is
In general, the following formula T: Solidification shell thickness (related) k: Solidification coefficient (am-min -2) t: Time from the start of solidification (min) L: Distance from mold medicine M (11) V: Continuous construction Since it is defined by the speed (m1n), 1 is significantly changed from 2 to 3 because of k.
It became clear that it would be difficult to make it twice as thick, and that the above proposal was at least impractical.

This is an advantageous means of cutting a piece that leaves an internal unsolidified no. By doing so, it is possible to seal the unsolidified molten steel between the crimped and solidified shells, that is, the concept of the present invention can advantageously solve the problem.

Now, the basic formula for determining the cutting position of a four-continuous cast body is (1)
Since the solidified shell thickness is given by T=, - according to the formula, it depends on the following formula (2).

L-÷v(D%yj Song... Song (2) D8 casting W thickness (-) d: Unsolidified layer thickness (Koji) In this invention, prior to cutting at this cutting position, four continuous 1 g of unsolidified material surrounded by a solidified shell that is growing after secondary cooling is applied to the cast body, and pressure is applied to the molded body to cause local mutual pressure bonding on the inner surface of the solidified shell.

Due to this squeezing pressure, the unsolidified molten steel is confined in the volume restrained by the solidified shells that are pressed against each other, but the internal pressure does not increase significantly, so such mutual pressure between the solidified shells may cause bulging between the rolls. This helps to avoid shrinkage caused by solidification of the solidified shell.

As a result, the occurrence of wrinkles due to shrinkage is prevented.

When a continuous cast body is rolled down and cut while still containing an unsolidified layer, the ratio of the thickness of the solidified shell that has grown and thickened to the thickness of the slab influences bulging1. The inventors have confirmed that good results can be obtained by using the method.

The cutting that follows this rolling can be a simultaneous mechanical operation following the rolling process or, of course, a subsequent mechanical or metallurgical operation.

As for the mechanical cutting operation, it is preferable to use shearing, but it may also be a process that involves compression, such as pressing down the cutting blade. can be used arbitrarily, and torch cutting is particularly convenient.

Now, Fig. 1 shows an example in which the present invention is applied to an existing continuous casting machine. Molten steel 1 is injected into the water-cooled leg of the continuous casting machine, passes through the water-cooled P4W, the secondary cooling zone 3, and then becomes the solidified shell q. During the growth of , the continuous casting body 6 with a thickness of D is obtained by continuous drawing with a pinch roll j, and this continuous casting body is located at a distance HLo from the mold meniscus 7, where unsolidified IfI is almost completely eliminated. It is customary to cut, for example, by torch cutting t. In this invention, prior to such cutting, a static reduction is applied by, for example, a hydraulic press 9 over the entire width of the continuous casting weight at a position from the mold meniscus 7 to Ll, which is far before the distance $11Lo, in the thickness direction. By adding the unsolidified layer to the thickness d of the continuous casting body 6, the inner surfaces of the upper and lower solidified shells of the continuous casting body 6 are locally pressed against each other. Under high speed, the unforged solid solution can be trapped between the compression solidification zones to produce a slab.

Figure 2 shows an example in which cutting is performed using a press shearing blade lO in one action operation following the mutual crimping of the solidified shells, and this shearing operation is performed at the pressurizing position shown in Figure 1. Just set it in the same way.

The position of the above-mentioned crimping or shearing may be determined based on the prediction of the growth of the solidified shell, which is unlikely to occur.

Example 1 In an existing continuous casting machine, from mold tome 4 scrap 7 to B
The cutting equipment installed at m (Lo) is t of conventional equipment, and the molten steel composition is aO, t, SiO, , 2'
4, Mn /, 0911, thickness of remaining Fe, 2jOss
Continuous casting of l slabs was carried out.

According to this invention, the distance tOv from the mold meniscus 7
Hydraulic press 9f at position m (Ll): installed as shown in Figure 1, casting speed! IILλvs / min is estimated to be approximately 47ss as a drawing, and the casting speed can be increased six times to that of the conventional method without causing bulging, and the length that contains unsolidified molten steel inside by subsequent torch cutting can be increased. A hot piece of IOIm was obtained.

Example 2 In the existing continuous casting machine shown in Figure 1, the molten steel composition was 70%.
0. (81(4, Si tr , MnO, 30
Rumored, kl'0.0/, continuous casting of +4 Miko go ■ with remaining Fe.

According to this invention, the distance ty, s from the mallet green scum 7
The press shearing blade 10 is installed at the position of m (Ll), and the casting speed is set to 3. , r m/min, the solidified shell was crimped and cut at intervals of /7*1''.

(N1 arrival. O, yo, shell thickness 04. Coefficient, -6゜□. - Estimated to be approximately 73 m, the casting speed is increased to approximately 2.1 times of the conventional method without causing bulging. Length that can contain unsolidified molten steel/7.j m
O high @ chicken pieces were obtained.

Example 3 In an existing continuous casting machine, the steel composition is OO, /J-1
Si 0-20 fk %Mn 0-10 Arrogance, remainder F
Continuous casting of JQQwa was carried out on the shore of e.

According to this invention, the distance from the mold meniscus 7 @r−≦
(2) The press shearing cutter 10 was installed at the position (Ll), and the continuous cast body was pulled out at a casting speed of HA/min. For every ≦■, one behavior operation of crimping and cutting of the solidified shell was added. During this crimping, the solidification thickness is determined by the solidification coefficient, lfw・
As m1n-+, it is estimated to be approximately W■? , the casting speed can be increased to almost twice that of the conventional method without causing bulging, and the cast iron contains unsolidified bath steel inside.
A hot-piece of tm was obtained.

As is clear from the description of the above-mentioned embodiments, this invention increases the casting speed by approximately 6 to 1 times compared to the conventional case where cutting is performed after waiting for the completion of solidification, so that there is no solidification inside. It is possible to obtain hot slabs containing layers without causing any problems due to bulging, and therefore this hot slab can be used for direct rolling or hot slab charging! Therefore, it is also useful for energy saving and can lower the unit heat consumption of the heating furnace.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams showing embodiments of the present invention. Patent applicant: Kawasaki Steel Corporation

Claims (1)

[Claims] L. Molten steel is injected into a water-cooled mold of a continuous casting machine, passes through the water-cooled mold, passes through a secondary cooling zone, and is continuously obtained by cutting the continuous cast body at a predetermined length. A method for cutting a continuous cast body, which comprises applying pressure to the solidified shell sandwiching the unsolidified layer remaining inside the continuous cast body to cause local mutual pressure bonding on the inner surface of the solidified shell.