JPH01501455A - Apparatus and method for continuously casting steel slabs - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Apparatus and method for continuously casting steel slabs Technical field This invention provides a method for continuously casting metal at high temperatures by adding water or water to the mold tube. or of high-temperature metals that have been cooled by injecting them with other coolants. Concerning continuous casting equipment. More specifically, this invention involves cooling into thin slab molds. Provides a device and method for controlling and cooling the material by spraying it. do.

Background technology In traditional continuous steel casting methods, the steel melt is placed vertically, usually in a curved It is made to pass through a copper mold. m of hot water passes through this mold. Over time, the outer shell of the hot water solidifies. As the steel strand solidifies this It is bent over several degrees and guided horizontally, then cut into individual slabs. Ru.

The temperature of hot water for steel is usually 2850 JtF, but depending on the type of steel it can reach 2600 degrees F. Can be any lower temperature. The following explanation mainly refers to steel casting. However, this invention is suitable for use in cases where the temperature of the hot water exceeds 2600 degrees Fahrenheit in poor melting conditions. It can also be applied to the casting of metals and alloys.

The mold that forms the steel strand receives the steel and provides initial solidification. i.e. outside Allow the side shell parts to start solidifying. Is the solidifying strand at the bottom of the mold? The hot water is continuously drawn out at the same rate as the hot water supply at the top of the mold. production speed The temperature depends on the time it takes for the outer shell to solidify and become able to hold the hot water inside. It is decided.

Slab-shaped products (usually rectangular, 2 inches or thicker, ’Z130 to 1 00 inches), modern equipment for continuous casting of It has a conventional construction consisting of a flowing sheet of water and a baffle tube. this Cooling methods are those in which the cooling system inherently removes heat (expressed in BTU/min) in a controlled manner. Particular difficulty in casting slabs due to inability to perform It turns out that it is. In particular, the corners of the slab form an externally facing ´ angle. solidifies faster than larger surface areas. The result of such uneven cooling Shrinkage occurs and cracks appear in the center of the large surface area of the slab, as well as on other faces and corners. Good luck will occur.

The greater the ratio of eccentricity to thickness, the larger the surface area of the cast slab. The tendency for cracks to grow increases. Generally speaking, the width to thickness ratio is 12 : If it exceeds 1, the slab is more likely to crack (called surface crack tendency). increase When using a mold with a conventional configuration, the width to thickness ratio is As the increase increases as shown in the figure, heat extraction is controlled in proportion to solidification and cracking. It becomes increasingly difficult to control If the ratio exceeds 30=1 or When the rub thickness was less than 1.25 inches, conventional cooling methods were used. It is very difficult to control the surface crack tendency with molds, and operators the need to take special measures, such as significantly reducing the casting speed. This may result in lowering the production capacity of casting equipment or reducing the quality of cast products. It will lower the quality.

Once a crack has formed, measures must be taken to prevent the crack from growing. However, such means can effectively control the removal of heat within the mold. Therefore, it is often necessary to stop the operation of the casting machine.

Disclosure of invention The inventor has determined that the cooling rate, or heat removal, of various regions of a slab casting mold can be adjusted to a given parameter. By controlling according to parameters, the production capacity of the casting equipment may be adversely affected. For example, we found that it is possible to control the surface crack tendency. , as disclosed in U.S. Pat. No. 4,494°594. technology to accurately control heat removal from cast slabs of various dimensions. This makes it possible to achieve a width-to-thickness ratio of 30:1, which was previously impossible. The surface crack tendency is also high for objects that exceed 1.25 inches or are less than 1.25 inches thick. It becomes possible to control the direction accurately. According to the device and method of this invention , width-to-thickness ratio of 100:1 or greater, and/or thickness of 1 inch. It is true that slabs can be cast well even if the conditions are not met. .

Monitoring the heat removal rate (BTU/min) at various areas of the mold's outer surface By controlling the surface crack tendency without compromising the production capacity of the equipment It is possible to do things.

In addition, by controlling the heat removal rate, it is possible to improve the quality of cast shafts. It will produce results. Basically, slab casting molds are as follows for control purposes: Divided into 4 cooling zones.

Area 1 Corner Area: Extends the entire length of the mold, approximately 2 inches on each side from the edge of the mold. part.

Area 2 Upper surface area: 6 inches below the meniscus from the top of the mold on both sides of the mold. The part that extends to a position.

Area 3 Intermediate surface area: On both sides of the mold, from 6 inches below the meniscus to 2/2 of the mold. The part extending to a point of length 3.

Area 4 Lower surface area: Approximately the length of the mold at the lower end of the middle surface area on both sides of the mold. 273 to the exit end of the mold.

Appropriate heat removal rates can be achieved by preparing multiple spray nozzles with various flow characteristics. group them against the mold and against each other according to predetermined parameters. This can be achieved by organizing and organizing. each nozzle glue The flow rate of coolant to the pool depends on the specific heat removal rate as well as the heat removal between different zones. Fl is adjusted to achieve a specific correlation of retention rates. According to a practical method, The operator monitors the heat removal rate in each zone as the casting progresses and Adjust the flow rate accordingly.

The heat removal rate in one cooling zone depends on, for example, casting temperature, casting speed, and the steel being cast. Depending on the casting conditions such as the quality of the , must be evaluated and specifically determined, however, the majority of steel types There is a heat removal rate that covers the expected casting conditions. The correlation between simultaneous heat removal in regions 1.2.3 and 4 is shown in Table 1. monitoring, and if it deviates from a predetermined range, adjustments are made. Actual operating date The data can also be evacuated and this information stored in a computer. Just like that For example, sensors placed at various locations on the mold can be used to transmit measurements to other working parts of the casting machine. By linking with parameters, the operation in each cooling area can be controlled by a computer. Therefore, it can be controlled.

Table 1 Relationship between removal rate and cooling area From the table above, it can be seen that the maximum heat removal occurs in region 2, i.e. from the top of the mold to just below the meniscus. area, and the next highest heat removal rate is at the exit of the mold. This occurs in region 4, which corresponds to about 1/3 of the total length of the mold from the mouth end. As can be understood, the middle part has the second largest heat removal when viewed in the length direction of the mold. However, the heat removal rate in the corner part (area 1) is the minimum as shown in Table 0. Compared to conventional technology, by adopting parameter values that fall within the approximate range of Excellent metallurgical quality with no or no cracks It is possible to cast slabs reduced to .

It is therefore an object of this invention to eliminate or significantly reduce clubking on slab surfaces. The object of the present invention is to provide a slab casting method and apparatus that can achieve the desired results.

Another object of this invention is to provide mold tubes and the metal therein in various areas of the mold. are cooled at different cooling rates, thereby preventing surface cracking and the like of the product slab. The object of the present invention is to provide a method for casting metal slabs that can prevent other defects.

Still another object of the invention is that the mold tube for casting the slab is sprayed onto its surface. In a slab casting machine where the slab is cooled by a coolant liquid, the coolant The amount of spray is adjusted so that the amount of heat removed is different in different areas of the mold. , thereby leading to surface cracks and other defects in the cast slab. To provide a slab casting equipment that can reduce or eliminate be.

Yet another object of the invention is a method and apparatus for casting slabs of metal. As a result, the amount of coolant sprayed onto the mold's outer surface can generate different heat waves in different areas of the mold. heat removal rate and minimum heat removal rate at the corners of the mold. control, thereby reducing the occurrence of cracks on the surface of the slab. It concerns casting decisions and controls for metal slabs, such that corrosion is eliminated.

Brief description of the drawing For a better understanding of the above and other objects and advantages of this invention, please refer to the accompanying drawings. In these drawings, which will become clear from the description of the embodiments that follows with reference to Like parts are designated with like reference numbers.

In the attached drawings, Figure 1 shows a known slurry in which coolant is circulated around the outer surface of the mold tube. FIG. 2 is a somewhat schematic perspective view of a tube casting device.

FIG. 2 is an end view of the mold tube and slab shown in FIG.

Figure 2 is a schematic perspective view of a mold tube showing different cooling zones according to the invention; .

Figure 4 shows a schematic diagram of a shimezu slab mold with a spray cooling device according to the present invention. It is a schematic perspective view.

FIG. 5 is a cross-sectional view of a typical slab showing the relationship between width and thickness.

BEST MODE FOR CARRYING OUT THE INVENTION In the drawings, a typical conventional system is shown with reference numeral 1 in FIGS. It is indicated by 0. In this system, the cooling stream, usually water, The body extends outside the mold tube 11 in a direction opposite to the flow direction of the molten metal in the mold tube. It is designed to circulate in both directions. The cooling water in this system is baffled Enclosed in a tube device to control the cooling rate in different areas Therefore, due to the shape of the mold and the exposed area at the corners of the mold. Due to the large heat removal rate at the corners, the casting Stress is generated on the central surface of the manufactured slab, resulting in cracks. this According to known methods and apparatus, the ratio of width W to thickness T is greater than or equal to about 12=1. If this ratio exceeds approximately 30=1, the propensity for cracking will increase. The probability of lock occurrence increases.

However, according to the invention, FIG. 3 and FIG. As shown at 5, a spray cooling system 16 is provided for supplying cooling fluid. is designed to direct multiple sprays of water onto the outside surface of the mold tube. The spray nozzles in the cooling system are selected to have different flow rates, and The mold is divided into a plurality of regions, i.e. regions, having different heat removal rates in BTU/min. 1.2.3.4 against each other and in groups in such a manner that they are divided into The position is out of alignment with the mold. Maximum heat removal rate as shown in Table - occurs in region 2 and the lowest heat removal rate occurs in region 1. These cooling The speed is carefully selected in advance and depends on the type of metal being cast, the casting speed, and the casting temperature. Depending on conditions such as can be cooled, thereby reducing or eliminating the stress on the surface. This can prevent the occurrence of locks.

The flow rate of the coolant to be sprayed and the absolute heat removal rate in BTUZ. Since the values vary depending on the parameters mentioned above, the limitations made here will be different in different areas. However, specific values are not indicated as limits. , the ranges shown are compatible with most grades of steel and the castings mentioned here. This applies to the predictable values of the construction conditions.

As mentioned earlier, in the present invention, multiple sensor probes are placed inside the mold itself. Measure and detect parameters such as temperature by strategically positioning the The different areas of the mold are controlled by a computer 19 which is programmed to operate accordingly. heat removal in these areas by controlling the flow rate of coolant sprayed in these areas. By adjusting the rate, high quality slabs can be obtained.

The above is a detailed description of the present invention. Any modification of construction or operation may be made without departing from the spirit of the invention as defined by the appended claims. It is possible to change the behavior.

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Claims (14)

[Claims] 1. In continuous casting molds for casting slabs of metal, a mold tube having a rectangular cross section; a plurality of spray nozzles disposed around the outside of the mold tube, the cooling directing a spray of fluid toward the mold tube, thereby causing the mold tube to a spray nozzle adapted to cool and solidify the metal being cast within; Controlling the flow rate of coolant in the spray nozzle at different areas of the mold Stresses due to uneven cooling on the slab resulting in different heat removal rates to reduce or eliminate the occurrence of cracks in the slab. 1. A continuous casting mold, characterized in that it has control means of 2. The region includes a first region extending in the length direction of the mold in a corner part of the mold. and sequentially along the surface of the mold from the inlet end to the outlet end of the mold. Claim 1 comprising a second, third and fourth region provided. Continuous casting molds as described in Section. 3. The second region is approximately 6 inches below the entry end die meniscus of the mold. 3. A continuous casting mold according to claim 2, characterized in that it extends to the point. 4. The third region extends from the lower end of the first region to about 2/3 of the length of the mold. 4. A continuous casting mold according to claim 3, characterized in that the continuous casting mold extends at 5. The fourth region extends from the lower end of the third region to the outlet end of the mold. The continuous casting mold according to claim 4, characterized in that: 6. The heat removal rate is maximum in the second region, and the heat removal rate is maximum in the first region. 6. The continuous molding mold according to claim 5, wherein the continuous casting mold has a minimum amount of water. 7. Heat removal in the first region of the heat removal rate obtained in the second region Claim 6, characterized in that the maximum ratio to the ratio is 3.6/1.0. Continuous casting mold. 8. Heat removal in the first region of the heat removal rate obtained in the third region Claim 7, characterized in that the maximum ratio to the ratio is 1.6/1.0. Continuous structure mold. 9. Heat removal in the first region of the heat removal rate obtained in the fourth region Claim 8, characterized in that the maximum ratio to the ratio is 2.5/1.0. Continuous casting mold. 10. The absolute value of heat removal in each zone in BTU/min is in the second region from about 2,880 to about 10,656, and in the second region from about 9,600 to about 10,656. approximately 35,520, and approximately 4,800 to 17,760 in the third region; The fourth region is about 6,720 to about 24,864. Continuous casting mold according to scope 7. 11. The molten metal is passed through the mold tube and solidified into the casting process. The stage of making love, The mold is designed to reduce or eliminate surface cracking in cast slabs. The mold tube is thus being cast with different cooling rates in different areas of the continuous casting of slabs of metal, characterized in that it includes a step of cooling the metal; how to. 12. A cooling region is provided in a corner section of the mold in the length direction of the mold. a first region extending from a mouth to an outlet; and an inlet of the mold along a surface of the mold. 4 including second, third and fourth regions provided sequentially from the end toward the outlet end; 12. The continuous manufacturing method according to claim 11, wherein the continuous manufacturing method has two regions. 13. The second region is approximately 6 inches below the meniscus from the entrance end of the mold. the third region extends a length of the mold from the lower end of the second region; the fourth region extends from the lower end of the third region to about two-thirds of the way through the mold; 13. Continuous manufacturing method according to claim 12, characterized in that it extends to the outlet end. 14. The absolute value of heat removal in each zone in BTU/min is in the second region from about 2,880 to about 10,656, and in the second region from about 9,600 to about 10,656. approximately 35,520, and approximately 4,800 to 17,760 in the third region; The fourth region is about 6,720 to about 24,864. The continuous manufacturing method according to scope 13.