JPH01218744A - Twin drum type continuous casting machine - Google Patents

Abstract

PURPOSE:To freely control distribution of thicknesses to width direction of continuous cast strip and to improve working efficiency in cold-rolling stage after that by adjusting cooling condition to width direction of a drum at the time of producing the metal strip from molten metal in twin drum type continuous casting machine. CONSTITUTION:The molten metal 4 is charged into molten metal basin part 3 constituting of two cooling drums 1a, 1b and side weirs 2a, 2b and both cooling drums 1a, 1b are rotated to mutually reverse directions, and the molten metal is continuously drawn from gap 5 between both drums 1a, 1b as the metal strip 6. In this case, both cooling drums 1a, 1b are deformed by heating with the molten metal 4 and as the width of drum gap 5 is varied to the drum axial direction, variation to the rolling reduction force applying to the solidified shell formed with the cooling drum is developed to change thickness of the metal strip 6. This is measured with a thickness meter 17 and by this result, coolant quantity or temp. from cooling water nozzle 11 for the cooling drums 1a, 1b is adjusted at plural position in the width direction of the drums to control the developing speed of the solidified shell. By this method, the continuous casting metal strip 6 without flaw, fold and crack is produced and working efficiency in cold-rolling at the next stage is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a twin-drum continuous casting machine that can adjust the thickness of a metal ribbon in the width direction.

[Prior Art] Recently, a method of directly manufacturing a metal ribbon having a thickness of several mm to several tens of mm, which is close to the final shape, from molten metal such as molten steel has been attracting attention. When using this continuous casting method, there is no need for a multi-step hot rolling process as in the conventional method.
Moreover, only a light rolling process is required to form the final shape.
It is possible to simplify the process and equipment.

Figure 3 shows the equipment configuration of the twin-drum method, which is known as one of the continuous casting methods (Japanese Patent Application Laid-Open No. 60-137
(See Publication No. 562).

In this system, a pool 3 is formed between a pair of cooling drums la and lbO that rotate in opposite directions, with side weirs 2a and 2b partitioning both ends in the axial direction of the drums. Then, the molten metal 4 is poured into the sump 3 and heat is removed from the molten metal 4 through the cooling drums la, lb, thereby forming a solidified shell on the circumferential surface of each of the cooling drums la, lb. As the solidified shell grows, the drum gap 5 increases as the cooling drums la and lb rotate.
to move to. With a drum gap 5, each cooling drum 1. The solidified shells formed on the peripheral surfaces of the sides a and lb are pressure-welded and integrated into the cooling drums la and l as thin metal strips 6.
It is carried out from between b.

In this twin-drum continuous casting machine, molten metal 4
The cooling drums la and lb are heated by the heat retained in the
The drum profile changes and the width of the drum gap 5 is no longer uniform in the axial direction of the drum. When the solidified shell is rolled down with such a drum gap 5, fluctuations occur in the rolling blade applied to the solidified shell, which causes defects such as cracks and wrinkles. Therefore, in order to maintain the drum profile in a predetermined shape, various means have been developed for deforming the cooling drums la, lb by pressurization or thermal contraction so as to offset the t1 thermal crown. -163057 Publication, JP-A-60-27458
(See Japanese Patent Application Laid-Open No. 61-262452, etc.).

[Problem to be solved by the invention]

However, in the conventional method, the
Wall thickness cannot be controlled in the width direction.

Therefore, the cooling drum, unevenness, lb profile,
Even if the profile is corrected, if the thickness distribution in the width direction of the solidified shell does not match, the distribution of the reduction amount in the width direction will become uneven, and defects such as cracks and wrinkles will inevitably occur. .

Furthermore, from the viewpoint of processing efficiency when processing the cast metal ribbon 6 in the subsequent cold rolling process, it is generally preferable to provide the metal ribbon 6 with a convex crown that is thicker at the center and thinner at both ends. On the other hand, depending on the application, such as electromagnetic materials,
In some cases, it is desired that the wall thickness deviation in the width direction be as small as possible. As described above, it is desired that the metal ribbon manufacturing process be capable of freely controlling the thickness distribution in the width direction.

However, no technology has been developed so far for producing a metal ribbon whose thickness varies in the width direction.

The present invention was developed to meet these demands, and by changing the cooling conditions in the axial direction of the drum, it is possible to freely control the widthwise distribution of the solidified shells growing on the circumferential surface of the cooling drum. The purpose of this method is to manufacture thin metal sheets with arbitrary wall thickness distribution without defects such as cracks and wrinkles, and to improve processing efficiency in subsequent processes such as cold rolling.

[Means for Solving the Problem] In order to achieve the object, the twin-drum continuous casting machine of the present invention rapidly solidifies molten metal supplied to the surfaces of a pair of cooling drums to produce a metal ribbon. In a continuous casting machine, the cooling drum is divided into three or more zones along the axial direction, and a nozzle for spraying the cooling drum is arranged to face the circumferential surface of the cooling drum, and the temperature of the refrigerant supplied to each zone is adjusted. and/or a control mechanism for controlling the flow rate is provided for each zone.

FIG. 1 is a side view showing the main parts of the twin-drum continuous casting machine of the present invention. In addition, in the same figure, parts corresponding to those shown in FIG. 3 are indicated by the same reference numbers.

In this continuous casting machine as well, a pair of cooling drums la and lb, which rotate in opposite directions, face each other as in the conventional casting machine. The heat of the molten metal 4 poured between the cooling drums la and lbO is removed through the cooling drums la and lb, and the metal ribbon 6 is sent out from the drum gap 5.

Then, a refrigerant 12 such as an emulsion containing water and a lubricant is sprayed from a nozzle 11 onto the circumferential surfaces of the cooling drums la and lb emerging from the water reservoir 3. As shown in FIG. 2, the nozzle 11 for this refrigerant spraying is divided into three zones I, I[, and III at both ends and the center in the axial direction of the cooling drums la and lbO.

Each zone 1. The refrigerant discharge ports 13 located in II and III are connected to the refrigerant supply pipe 1 via branch pipes 14 for each zone.
5. The refrigerant supply pipes 15 each include a flow rate regulating valve 16. In addition, in the refrigerant spraying, the number of zones of the nozzle 11 may be more than three, so that the cooling conditions in the direction of the drum axis can be controlled more precisely.

On the other hand, in order to measure the thickness of the metal thin strip 6 sent out from the cooling drums la and lb along the width direction,
A total of three thickness gauges 17 are arranged at the center and both ends in the width direction. The thickness distribution in the width direction of the metal ribbon 6 detected by the thickness gauges 17 is input to an appropriate calculator (not shown) to represent the refrigerant flow rate corresponding to the target peripheral surface temperature of the cooling drums la and lb. converted into a control signal. This control signal is input to the aforementioned flow rate adjustment valve 16.

Therefore, depending on the target thickness of the metal ribbon 6, the flow rate of the refrigerant 12 sprayed from the nozzle 11 onto the circumferential surface of the cooling drums la, lb is adjusted along the drum axis direction, and the cooling drums la, lb are sprayed. The circumferential surface temperature in the axial direction is made to correspond to a predetermined pattern.

In FIG. 2, the flow rate of the refrigerant 12 is determined by the cooling drum la, lb
By changing the axial direction of the cooling drum la, lb
The thickness distribution of the solidified shell growing on the circumferential surface of the drum in the axial direction of the drum is adjusted. However, as a method of controlling cooling conditions in the drum axial direction, cooling drum la,
It is possible to adopt a method of changing the temperature of the refrigerant 12 sprayed onto the circumferential surface of the lb.

In this case, the refrigerant supply pipe 15 is connected to storage tanks containing refrigerants at different temperatures.

Alternatively, a heater or a cooler is provided in the middle of the refrigerant supply pipe 15, and the heater or cooler is controlled based on information from the thickness gauge 17 to adjust the temperature of the refrigerant sent toward the refrigerant discharge port 13. You may do so.

In order to prevent the injected refrigerant from coming into contact with the metal ribbon 6 and the molten metal 4, it is desirable to provide shielding plates 18 on the upstream and downstream sides of the nozzle 11 for refrigerant spraying. At this time,
A magnet is attached to the tip of the shielding plate 18, and magnetic attraction forces the shielding plate 18 and the cooling drum la.

1b can be maintained at a small gap.

〔Example〕

Example 1 Using a cooling drum with an axial length of 800 mm and a diameter of 1200 mm, molten steel having a stainless steel composition of 5US304 at a temperature of 1490°C was poured into the pool at a flow rate of 1100 kg/min, and the wall thickness was 2 mm. , a metal ribbon with a plate width of 800 mm was manufactured. As the casting progressed, the cooling drum was heated by the molten steel and the profile of the cooling drum changed. Due to this profile change, the rolling blade applied to the solidified shell in the drum gap became uneven, and defects such as scratches and wrinkles occurred in the metal ribbon product.

This profile change appears as a thickness variation along the width direction of the metal ribbon fed out from the cooling drum. Therefore, the thickness of the cast metal ribbon was measured using a plurality of thickness gages 17 arranged in the width direction. The drum gap corresponding to the area where the measured wall thickness is large has a large gap due to the thermal crown of the cooling drum.

Therefore, the flow rate of the refrigerant sprayed from the nozzle 11 in zones I and I to the circumferential surface of the cooling drum corresponding to this portion was increased to 8 Nm'/min, respectively, and the growth of the solidified shell was promoted. On the other hand, for the center of the drum gap, which has become a small gap due to the thermal crown, the refrigerant spray in zone 1 is injected from the nozzle 11, and the flow rate is suppressed to 6 Nm + 7 minutes, suppressing the growth of the solidified shell. did.

In this way, since the growth of the solidified shell is controlled in accordance with the thermal crown, a uniform rolling edge acts on the solidified shell rolled down in the drum gap 5. Therefore, it was possible to produce a metal ribbon with a sound surface quality without the occurrence of scratches, wrinkles, cracks, etc. as in the conventional method.

81 Example 2: In order to improve processing efficiency in the cold rolling process, a metal ribbon with a width of 800 mm and a convex crown with a thickness of 2.1 mm at the center and 2.0 mm at both ends was cast. .

The cooling drum used at this time had a diameter of 12 mm at the center.
0 (1 mm), the diameter at both ends was 12'00.1 mm, and the axial length of the drum was 8'00 mm. Such cooling drums were placed facing each other as a pair, and the gap in the center was 2 mm.
, l mm, and a drum gap of 2.0 mm between both ends was formed.

In this drum gap, uniform reduction blades act on the solidified shell formed on the circumferential surface of each cooling drum.
The growth of the solidified shell in the direction of the drum axis is defined as zone 1. n
, III was controlled by varying the amount. That is, the flow rate of the refrigerant spraying in Zones I and III was 6 Nm + 7 minutes, respectively, and the flow rate of the refrigerant spraying in Zone ■ was 1 ON'm'' 7 minutes.As a result, the solidified shell that grew on the circumferential surface of the cooling drum was It has a cross-sectional shape with a convex crown that is thick at the center in the width direction and thin at both ends.Because of this convex crown, the rolling edge applied to the solidified shell in the drum gap is uniform, resulting in a defect-free metal ribbon. could be manufactured.

On the other hand, when casting was performed using a cooling drum with a uniform flow rate in the axial direction of the drum, the solidified shell that grew in the center was insufficient to fill the large gap in the center of the drum gap. It was so thick that the rolling blade did not work properly. Therefore, the obtained metal ribbon has scratches and wrinkles.

Defects such as cracks were particularly severe in the center of the width.

〔Effect of the invention〕

As described above, in the present invention, the cooling conditions for the circumferential surface of the cooling drum are independently controlled at least at the center and both ends in the axial direction of the drum. Therefore, even if the gap in the drum gap changes in the drum axial direction due to the occurrence of a thermal crown, for example, by controlling the growth of the solidified shell to offset the variation in the gap, the reduction in pressure in the drum gap can be reduced. The reduction edge applied to the solidified shell can be made constant. In addition, when manufacturing a metal ribbon with a convex crown that is effective for cold rolling, the growth of the solidified shell can be controlled in the direction of the drum axis, so the solidified shell that is rolled down in the drum gap is similarly subjected to The rolling blade remains constant. In this way, the solidified shell is rolled down with a constant rolling blade, so the obtained metal ribbon has no scratches or wrinkles.
It has no defects such as cracks and has excellent surface quality.

[Brief explanation of the drawing]

FIG. 1 is a diagram for specifically explaining the present invention, and FIG. 2 shows the relationship between the cooling drum and the refrigerant spray nozzle. On the other hand, FIG. 3 shows a conventional twin-drum type continuous casting machine. Patent applicant: Nippon Steel Corporation (one idiot)
Masato Kobori (and 2 others) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a continuous casting machine that manufactures metal ribbon by rapidly solidifying molten metal supplied to the surfaces of a pair of cooling drums, a refrigerant spray nozzle divided into three or more zones along the axial direction of the cooling drums. twin-drum continuous casting, characterized in that each zone is provided with a control mechanism for controlling the temperature and/or flow rate of the refrigerant supplied to each zone. Machine.