JPS59212162A - Gas sealing method of charging flow - Google Patents

Abstract

PURPOSE:To perform satisfactorily oxidation-free casting with the smaller amt. of an inert gas to be used by attaching a nozzle for gas sealing having double slits onto the outside circumference of a ladle nozzle and discharging air from the outside slit and the inert gas from the inside slit. CONSTITUTION:An inert gas 8 is admitted through a nozzle 7 into a casting mold 1 to maintain an oxidation-free atmosphere in the mold after the air is sucked therefrom through a suction nozzle 5. A nozzle 12 for gas sealing is attached onto the outside circumference of a ladle 11 underneath a ladle 10 and the nozzle 12 is fixed onto the sprue 9 of the mold 1. Air 14 is discharged from the outside slit 13 formed to the shape expanded outward at about 5-10 deg. angle to form an air curtain and while an inert gas 16 is discharged from the inside slit 15 of the nozzle 12, a molten metal is charged from the ladle 10 into the mold 1. The outflow of the air 14 and the gas 16 is continued until casting is completed.

Description

Detailed Description of the Invention The present invention uses a nozzle with a simple structure to prevent the formation of secondary oxides due to the entrainment of air in the pouring flow, thereby completely achieving oxidation-free casting in an inert gas atmosphere. The present invention relates to a gas sealing method.

Generally, performing construction in a vacuum atmosphere is an effective method for manufacturing products with fewer defects. However, due to the size of the vacuum container, etc., the size of the casting cut that can be used for vacuum breast sculpting is limited. Therefore, in large castings, in order to obtain the same effect as vacuum casting, casting is carried out in an inert gas atmosphere using an apparatus 7'' shown in FIG.

In FIG. 1, 1 is a mold, 2 is a fixed plate, and 3 is a mold flask.The mold flask 3 is in contact with the mold 1, and a partition wall 4 is provided with a large number of pores that prevent molding sand from passing through. The inside of the mold 1 is sufficiently evacuated through the partition wall 4 by suctioning from a large number of suction nozzles 5 provided on the outer surface of the mold flask 3.

Thereafter, an inert gas 8 is caused to flow into the mold 1 from a nozzle 7 attached to a lid 6 provided on the upper part of the mold 1 to create a sufficiently oxygen-free atmosphere inside the mold 1. Also lid 6
A sprue 9 is provided for pouring in the molten metal. The ladle 10 is filled with bath water, and the ladle nozzle 11 at the bottom of the ladle 10 is connected to the spout. Pour hot water by holding it in place. This allows the casting to solidify in a completely oxygen-free atmosphere! , I, but there is a problem of air being drawn in when pouring from the ladle.

Therefore, it is very important to create a non-oxidizing atmosphere using an inert gas when pouring hot water from a ladle. As a method of creating a non-oxidizing atmosphere using an inert gas, there is a method in which the inert gas is flowed out perpendicularly to the pouring flow, but these methods require a large amount of inert gas.

As a result of intensive research, the present inventors have discovered a method of creating a sufficiently oxygen-free atmosphere between the ladle nozzle and the sprue using a smaller amount of inert gas than before, and have completed the present invention.

That is, the gist of the present invention is that when pouring molten metal from a ladle into a mold, a gas sealing nozzle having double slits on the outside and inside is attached to the outer periphery of the ladle nozzle, and the outside Air flows out from the slit to form an air curtain, and inert gas flows out from the slit in one direction to create a gas seal and create an oxygen-free atmosphere in the pouring stream.

A more preferable configuration of the present invention is to form an air curtain by causing air to flow out at high speed from an outer slit that is widened outward at an angle of 5 to 10 degrees, and further to allow inert gas to flow out from an inner slit. be. The reason for using the widened slit is to prevent air from entering the sprue. When air flows out at high speed to form an air curtain, the gas inside and outside the air curtain will collapse into the air curtain. Therefore, by letting the inert gas flow out from the inner slit,
The inside of the air curtain is filled with inert gas to prevent air from entering from outside the air curtain.

Next, embodiments of the present invention will be explained in detail with reference to the drawings. In FIG. 1, after suction is performed from the suction nozzle 5 in the same manner as described above, the nozzle 7 is activated.

The inside of the mold 1 is made to have an oxygen-free atmosphere.

A gas sealing nozzle +2- as shown in FIG. 2 (AJ) is attached to the ladle nozzle 11 at the bottom of the ladle 10.

In Fig. 2(A), 11 is a ladle nozzle, ■ is a gas sealing nozzle, and 15 is an outer slit of the gas sealing nozzle. This causes the air 14 to flow out. Reference numeral 15 denotes an inner slit across the gas sealing nozzle, from which an inert gas 16 is allowed to flow out. The ladle nozzle 11 and the gas sealing nozzle 214 attached to the outer periphery of the ladle nozzle 11 are fixed onto the sprue 9 of the mold shown in FIG. 2(B).

Outer slit 13, high-speed air 14, inner slit 1
5. Casting is started without allowing the cine active gas 16 to flow out, and the air 14 and inert gas 16 continue to flow out until the casting is completed.

By implementing the present invention as described above, secondary oxidation of the molten metal during casting can be prevented, and a sound casting without inclusions can be manufactured. Furthermore, the amount of inert gas used is small compared to the conventional method in which only inert gas is allowed to flow out perpendicularly to the pouring flow, which is advantageous and economical.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the outline of the non-oxidation casting method;
Figures (A) and (B) are gas seal nozzles [Figure 2 (A)
)] and sprue [Fig. 2 (This is a cross-sectional view shown by BJC.

Claims (1)

[Claims] When pouring molten metal into a mold from a ladle, a gas sealing nozzle with double slits on the outside and inside is attached to the outer periphery of the ladle nozzle, and air flows out from the outside slit to form an air curtain. , a pouring flow gas sealing method characterized by causing inert gas to flow out from a slit in one direction.