JPH036436B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cleaning metal oxides in a molten metal stirring apparatus.

In furnaces for melting metals such as aluminum, copper, and zinc, if the molten metal is not stirred, the melting time becomes longer, the temperature at which it must be heated becomes higher, and the amount of oxides generated increases. It is known to be a cause of low quality and high costs. Therefore, in order to suppress the oxidation phenomenon and obtain a high quality product, it is required to lower the heating temperature and shorten the time required for melting, and stirring the molten metal is very useful for this purpose. In the case of aluminum, the amount of oxide generated by stirring,
Approximately 10% reduction in both melting time was observed. However, the current situation is that the remaining 90% of oxides cannot be removed.

As a well-known example of a mechanical stirring device that performs an effective stirring operation, as shown in FIG. Attach a pump cylinder 4 whose inner wall is lined with a fireproof material. Above communication hole 2
The pump cylinder 4 is communicated with the inner bottom of the melting furnace 1 through a ventilation pipe 8 which has an automatic switching valve 5 between outside air and negative pressure, a cyclone 6, a filter 7, etc. The upper part of the vacuum blower 9 is connected to the vacuum blower 9. The vacuum blower 9 is operated by a motor 10 to apply vacuum pressure in the pump cylinder 4 to draw the molten metal into the cylinder 4, and after a certain period of time has passed, the automatic switching valve 5 is switched to supply outside air to the cylinder. Introduce. Since the vacuum suction force is removed and outside air is introduced, the molten metal sucked up into the pump cylinder 4 returns to the melting furnace 1 by its own weight, causing convection in the stagnant molten metal and stirring the inside of the melting furnace 1. However, the metal oxide 12 (1) oxidizes on the surface of the molten metal in the furnace;
Oxide 1 is also present on the surface of the molten metal 11 in the cylinder 4.
When 2' is generated, sucked into the cylinder 4, and discharged, it always remains in the cylinder 4.

(2) Oxide 12 on the surface of the molten metal may be inhaled due to clumsy operation when charging the refrigerant.

(3) As a result of taking out the molten metal 11, if the molten metal level in the furnace has dropped to near the communication hole 2 at the bottom of the cylinder and the cylinder 4 is inhaled, the metal oxide 12 on the surface will be inhaled. Sometimes it happens.

For the reasons mentioned above, the metal oxide is sucked into the cylinder 4, and once introduced, the oxide does not come out except when the cylinder 4 is emptied. For this reason, oxides adhere to the pipe wall inside the cylinder 4, and at the same time, metal oxides adhere to the water level 14 of the molten metal that is constantly sucked in during normal operation.
This significantly narrows the inner diameter of the cylinder and obstructs the flow of molten metal within the cylinder during operation. Furthermore, since the melting furnace 1 is operated in a so-called run-up operation in which the molten metal is taken out to the outside while the cold material is put in, it has the disadvantage that cleaning the cylinder is extremely difficult.

The present invention has been made to solve the above problems, and is a molten metal agitation system that allows metal oxides adhering to the inside of a cylinder wall communicating with a melting furnace to be removed very easily to obtain a high-quality product. The purpose of the present invention is to provide a method for cleaning oxides in an apparatus, in which molten metal is periodically sucked into a cylinder by creating a vacuum in the cylinder, and the molten metal is discharged into a melting furnace. In a molten metal stirring device, a timer that adjusts the operating time of the vacuum pressure is attached to the automatic switching valve between outside air and negative pressure, and the vacuum operating time of the timer is adjusted to a longer time, and the vacuum pressure in the cylinder that is sucked is It is characterized in that the water level is raised above the normal water level, and the metal oxide sucked into the cylinder, which is near the normal water level, falls under its own weight.

Next, the present invention will be explained with reference to the drawings. FIG. 1 shows a schematic diagram of a molten aluminum metal stirring apparatus. Metal oxides have the property of becoming more softened by increasing the temperature. As a means of increasing the temperature of the aluminum oxide 13 that has adhered in the cylinder 4, suction and discharge of the molten metal from the melting furnace 1 into the cylinder 4 is carried out by raising the suction water level of the molten metal to a level exceeding the position of adhesion in the cylinder. This is done by repeating. As a result, the adhered metal in cylinder 4 is
Since it is located inside the molten metal sucked into the cylinder 4, the temperature of the adhered metal becomes higher than when it is located on the surface of the molten metal.
This will cause the adhesive metal to soften. Furthermore, the temperature of the molten metal during normal stirring is, for example, about 650°C, but after the melting is completed, it rises to 700-750°C, so cleaning the inside of the cylinder 4 at this time is more effective. It is. However, it is not limited to this point. On the other hand, the vacuum blower 9 is operated by the rotation of the motor 10 to create a vacuum pressure in the cylinder 4, and the molten aluminum 11 is transferred to the cylinder 4.
Let it be sucked inside. During this suction, a timer for adjusting the switching time length between the outside air and the vacuum blower 9 is attached to the automatic switching valve 5 in advance. With this timer adjustment, after vacuum suction for a longer time than the vacuum suction time during normal stirring, the automatic switching valve 5
is switched to introduce outside air into the cylinder 4, and the molten aluminum sucked into the cylinder 4 is caused to fall under its own weight and discharged into the melting furnace 1. That is, since the vacuum suction time became longer, the water level of the sucked molten aluminum in the cylinder 4 decreased by 15.
is higher than the water level 14 during normal stirring. The larger height difference between the height of the molten metal 11 in the furnace and the softening effect of the oxide due to the temperature rise makes it possible to efficiently wash away the aluminum oxide adhering to the inside of the cylinder 4. It goes without saying that the metal described above is not limited to aluminum, but may also be copper, zinc, or the like. According to the present invention, by repeating the above-mentioned washing operation several times, the washing can be carried out more effectively and a high-quality product can be efficiently obtained.

[Brief explanation of the drawing]

FIG. 1 shows a schematic configuration of a conventional aluminum metal molten metal stirring device. DESCRIPTION OF SYMBOLS 1...Metal melting furnace, 2...Communication hole, 3...Intermediate body, 4...Cylinder, 5...Automatic switching valve, 6
... Cyclone, 7 ... Filter, 8 ... Ventilation pipe, 9 ... Vacuum blower, 10 ... Variable speed motor, 11 ... Aluminum molten metal, 12 ... Aluminum oxide, 12' ... Aluminum oxide inside the cylinder 13...Aluminum oxide adhered to the cylinder inner wall, 14...Water level of sucked molten aluminum during normal stirring, 15...Water level of sucked molten aluminum during cleaning.

Claims (1)

[Claims] 1. In a molten metal stirring device of a type in which molten metal in a melting furnace is periodically sucked into a cylinder by evacuating the cylinder and the molten metal is discharged into the furnace, the vacuum pressure to the cylinder and the outside air are Attaching a timer for adjusting the operating time of the vacuum pressure to the automatic switching valve that switches the valve, adjusting the vacuum operating time of the timer to a longer time, and raising the water level in the sucked cylinder above the normal water level, A method for cleaning oxides in a molten metal stirring device, characterized in that the metal oxides near the normal water level sucked into the cylinder are allowed to fall under their own weight.