JPS60121047A - Horizontal and continuous casting method of metal - Google Patents

Abstract

PURPOSE:To know exactly the position where solidification starts and to prevent instruction of impurities into a casting ingot with a horizontal and continuous casting method by heating a casting mold to the m.p. of a molten metal or above, opening the top surface of the mold and providing a gate near the outlet thereof. CONSTITUTION:A casting mold 3 is heated to the m.p. of a molten metal 1 or above by a heating element 4 and the top surface thereof of the mold 3 is opened. A gate 14 is provided near the outlet thereof. The molten metal 1 in a holding furnace 2 solidifies from the inside of a casting ingot 7 in the mold 3 heated by the element 4 and the surface layer part is solidified near the outlet by cooling water 9 from cooling nozzles 8. The ingot is drawn out by draw-out rolls 10. The intrusion of the slag 13 floated and separated from the metal 1 into the ingot 7 is prevented by the gate 14 and since the upper part of the mold 3 is held open, the point where the solidification start is easily known. The quality of the casting is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a horizontal continuous casting method for metal, in which a continuous casting mold is heated so that the surface layer of the ingot drawn from the mold is formed near the exit of the mold. .

Traditionally, the horizontal continuous casting method uses a cooling mold with a central hole that runs through it, supplies molten metal from one end of the mold, solidifies the molten metal within the mold, and then continuously casts the slab horizontally from the other end. This method is widely used in the production of ferrous and non-ferrous alloys because it allows for miniaturization of equipment. In this method, the injected molten metal is rapidly cooled in the mold.
Solidification begins upon contact with the cooled mold, but the interior remains unsolidified. This unsolidified portion is held in a solidified shell and pulled out from the mold, undergoes secondary cooling, and is completely solidified while being conveyed out by rollers or the like.

In the conventional continuous casting method as described above, solidification starts from the outside and finally solidifies at the center, so that dendrites whose solidified structure is perpendicular to the casting direction are formed. In addition, impurities and the like are concentrated in the center, causing component segregation, and furthermore, defects such as play holes occur in the center.

For this reason, efforts have been made to disrupt the dendrites using electromagnetic stirring within the mold or during the ingot drawing process in order to homogenize the components, but this is not sufficient.

In addition, the ingot is pulled out intermittently to prevent adhesion between the cast metal and the mold and to prevent hot water from leaking, but the oscillation marks that are formed by this can cause cracks, and the surface of the ingot does not adhere to the mold. Surface defects are likely to occur due to friction, and surface care such as scratch removal and surface scraping is required.

Therefore, instead of using a conventional cooling mold, it has been proposed to solidify the molten metal from within and heat the mold to a temperature higher than the solidification temperature of the cast metal so that a surface layer of the ingot is formed near the exit of the mold. ing.

In this method, the inside and outside of the ingot progress almost simultaneously, so internal defects such as segregation are reduced, a unidirectional solidification structure in the casting direction is obtained, and the surface condition is extremely smooth. .

Furthermore, since there is no need for vibration of the mold or intermittent withdrawal of the ingot, it has extremely excellent characteristics in that no oscillation marks are formed. As mentioned above, an ingot having a unidirectional solidification structure has excellent workability in rolling, etc., and is suitable for materials that are difficult to work.

However, when this method is applied to the horizontal continuous casting method, solidification starts near the exit of the mold, so leakage occurs due to subtle changes in the mold internal temperature, cooling water temperature, and casting speed. For this reason, we devised a method to open the top surface of the mold so that the solidification start position could be observed. However, if the upper surface of the mold is opened in this manner, there is a risk that impurities such as oxides may be drawn into the ingot above the molten metal.

As a result of studies on this point, the present invention has been developed in a horizontal continuous casting method in which molten metal is supplied from one side of the mold and an ingot is pulled out from the other side. He devised a horizontal continuous casting method for metals, which is characterized by the provision of a weir near the mold outlet.

As a result, as mentioned above, with open-top molds, there was a risk that impurities such as oxides would float above the molten metal and be engulfed in the cast metal, but by providing a weir near the mold outlet, these oxides, etc. Impurities can be removed and casting defects can be reduced.

The upper surface of the mold may be opened completely or partially in the direction of the outlet of the mold, but opening the mold dissipates heat and lowers the temperature of the molten metal. It is necessary to sufficiently heat the open upper surface of the molten metal by resistance heating, gas heating, etc.

Therefore, in order to minimize the temperature drop of the molten metal as mentioned above, the exit direction of the mold is partially opened, and at the same time the upper surface is opened, a weir is installed to float and separate non-metallic inclusions mixed into the molten metal. It is desirable to remove impurities such as oxides and other impurities generated afterward by opening the top surface, and also to be able to easily determine the point at which solidification starts.

Further, when the solidification start point varies depending on the casting conditions, or when adjustment is required, or for adjusting a suitable position for removing impurities, the position of the weir can be made adjustable in the casting direction.

In this way, the present invention can improve the quality of castings by heating the mold, and as described above, it is possible to accurately determine the solidification start position, and it also eliminates the risk of impurities such as oxides getting caught up in the ingot. This is an extremely superior casting method.

Next, it will be explained along with the drawings.

FIG. 1 is an example of a vertical cross-sectional front view of a horizontal continuous casting apparatus in which the mold is heated to start solidification near the mold outlet and the top surface of the mold is open. The molten metal 1 in the holding furnace 2 is solidified from the inside of the ingot 7 in the mold B heated by the heating element 4, and the surface layer of the ingot 7 is solidified near the outlet of the mold 3. The ingot 7 is pulled out to the right in the figure by a pull-out μm lever 10. Heat is removed from the ingot by cooling water 9 from cooling nozzle 8.
Do this by spraying. The cooling means may be air cooling or box type indirect cooling. 5 is a scene control rod, 6 is a thermometer that continuously measures the temperature of the molten metal in the mold and the holding furnace, and 11 is a dummy bar.

As shown in this figure, since the inside of the mold is heated, the molten metal in the mold solidifies only through cooling of the ingot. Therefore, the ingot 7 starts to solidify from the inside, and the surface layer is heated. Therefore, solidification starts near the exit of the mold 6.

This shows a completely different solidification form from the conventional continuous casting method in which the mold is cooled. Therefore, this mold heating type continuous casting method makes it possible to produce ingots with a unidirectional solidification structure.
Defects such as segregation and blowholes in the center are reduced, and the surface of the ingot becomes extremely smooth, reducing surface defects.

Furthermore, by opening the top surface of the mold, the position of the solidified interface can be seen at all times, and by monitoring changes in the solidified area and adjusting the drawing speed and mold heating temperature, there is no risk of leakage. It has the disadvantage that oxides etc. are generated on the upper surface.

For this reason, in the present invention, a weir is provided on the upper surface of the mold as shown in FIG. This makes it possible to easily float and separate non-metallic inclusions in the molten metal and remove oxides generated on the top surface of the molten metal, thereby preventing impurities from getting caught in the ingot and wear and tear on the mold. The quality of cast metal can be improved.

As described above, the method of the present invention is an epoch-making method that makes it possible to produce an ingot with a unidirectionally solidified structure, and improves operational stability, quality and yield of cast metal.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an apparatus used in the horizontal continuous casting method using an open-top mold, and FIG. 2 is a longitudinal cross-sectional view of the apparatus provided with a weir and used in the horizontal continuous casting method of the present invention. 1: Molten metal 2: Holding furnace 3: Mold 4: Heating element 5: Level control rod 6: Thermometer 7: Ingot 8: Cooling nozzle 9: Cooling water 10: Drawer wheel 11: Dummy bar 12: Solidified shell 16: Mine slag Figure 1 Figure 2

Claims (1)

[Claims] In a horizontal continuous casting method in which molten metal is supplied from one side of the mold and an ingot is drawn from the other side, the mold is heated above the melting point of the molten metal, the top surface of the mold is opened, and a weir is provided near the mold outlet. A horizontal continuous casting method for metals characterized by: