JPH0351768B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention involves sucking up molten metal into a vacuum tank,
The present invention relates to a vacuum degassing device that performs degassing.

[Prior art and its problems] This type of vacuum degassing apparatus is shown in FIGS. 3 and 4.

Figure 3 shows the vacuum suction degassing method (DH method), in which molten metal 2 in a ladle 1 is sucked up into a vacuum chamber 3 installed upside down above the ladle 1, and the inside of the vacuum chamber 3 is The molten metal 2 is degassed. 4 is a vacuum pump that evacuates the vacuum chamber 3;

FIG. 4 shows the reflux degassing method (RH method), in which the molten metal is circulated through a rising pipe 6 and a descending pipe 7 provided in the vacuum tank 5, and degassing is carried out inside the vacuum tank 5. I try to do it.

However, since the vacuum chambers 3 and 5 used in the above-mentioned degassing equipment are lined with basic refractory material, molten metal tends to adhere to them, and furthermore, this refractory material itself is susceptible to thermal shock. Front vacuum chamber 3,
5 had to be heated to a high temperature by electrical resistance heating or the like. In addition, degassing equipment using this method does not have very good degassing efficiency and the degassing process takes time, so measures such as blowing argon gas into the vacuum chambers 3 and 5 and speeding up the degassing speed by stirring are taken. was necessary.

[Purpose of the invention] This invention was made to eliminate the above-mentioned problems, and aims to reduce the adhesion of molten metal to the refractory material in a vacuum chamber, extend the life of the refractory material, and improve degassing. The purpose is to provide a vacuum degassing device with enhanced effectiveness.

[Structure of the Invention] The vacuum degassing device of the present invention is a vacuum degassing device for vacuum degassing by sucking molten metal into a vacuum chamber, in which the vacuum chamber is formed of a refractory material that is conductive and has good wettability. Additionally, an induction coil is provided around the vacuum chamber.

[Embodiment] FIG. 1 shows an embodiment of the vacuum chamber degassing apparatus of the present invention.

10 is a ladle that stores molten metal 11 inside;
It includes a hot water inlet 10a and a hot water outlet 10b. 1
2 is a cylindrical vacuum chamber made of refractory material. This vacuum chamber 12 is formed into a cylindrical shape and is used as a vacuum chamber. The material for the vacuum chamber 12 is a dense material with low air permeability since it is necessary to maintain a vacuum, and a material that is conductive and has good wettability with the molten metal is used. Prevent molten metal, sludge, etc. from adhering. Specifically, graphite used for electrodes and the like is suitable. As other materials, carbon random, silicon carbide, etc. can be used, and if the material has high air permeability, it may be impregnated with tar or the like. The open lower end of the vacuum layer 12 is directly immersed in the molten metal, and the upper end of the vacuum layer 12 has a ventilation hole 1 for vacuuming.
2a is provided, and this ventilation hole 12a is connected to a vacuum pump (not shown). 13 is a heat insulating material provided so as to surround the vacuum layer 12, and a coil 14 for induction heating is provided around the outer periphery of this heat insulating material 13.
is installed.

In the above configuration, if AC current is applied to the induction coil 14 before evacuating the vacuum layer 12,
An induced current flows through the conductive vacuum layer 12, heating the vacuum layer 12 itself. Then, when the vacuum layer 12 is evacuated for degassing, the molten metal 11 in the ladle 10 rises into the vacuum layer 12. At this time,
Since the vacuum layer 12 is heated, there is no risk of damage due to thermal shock. Furthermore, during the degassing process, the molten metal 11 in the vacuum layer 12 receives electromagnetic induction from the induction coil 14, causing a molten metal stirring action, which improves the degassing speed and eliminates the need for stirring by blowing argon gas. . Furthermore, since the molten metal 11 is heated by induction, there is little temperature drop, which is advantageous in subsequent casting.

FIG. 2 shows another embodiment of the invention, in which the same parts as in FIG. 1 are given the same numbers.

In this embodiment, two vacuum chambers 12 are provided, and each vacuum layer 12 is provided with an induction coil 14, a ventilation hole 12a, etc., as in the previous embodiment.

When performing degassing treatment, the vacuum pumps that evacuate each vacuum layer 12 or the valves (both not shown) provided in the vacuum path between the vacuum pump and the vacuum layer 12 are controlled, and the two vacuum The layers 12 are alternately evacuated. Through such control, the level of the molten metal 11 in the ladle 10 can be kept constant, and the accuracy of the vacuum degassing process can be improved. Further, advantages are obtained in that the temperature of the molten metal 11 and the control when pouring in or out of the molten metal from the inlet 10a and the outlet 10b are facilitated.

[Effects of the Invention] As explained above, the present invention includes a vacuum degassing tank made of a refractory material that is conductive, has low air permeability, and has good wettability, and an induction heating coil is provided around the degassing tank. Since the refractory material itself is induction heated in advance, there is no fear that the refractory material will be damaged by thermal shock, and it is possible to prevent molten metal etc. from adhering to the refractory material. During the degassing process, the molten metal is subjected to electromagnetic induction by the induction coil and a stirring action of the molten metal occurs, so that the degassing speed is improved and stirring by blowing argon gas as in the conventional method is no longer necessary. Furthermore, since the molten metal is heated by induction, there is little temperature drop, which is advantageous in subsequent casting.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a vacuum degassing device which is one embodiment of the present invention, FIG. 2 is a cross-sectional view showing another embodiment of the present invention, and FIGS. 3 and 4 are conventional vacuum degassing devices. FIG. 10... Ladle, 10a... Hot water entrance, 10b...
Tap spout, 11... Molten metal, 12... Vacuum layer, 12a
...Vent hole, 13...Insulation material, 14...Induction coil.

Claims (1)

[Claims] 1. In a vacuum degassing device that vacuum degasses molten metal by sucking it up into a vacuum chamber, the vacuum chamber is made of a refractory material that is conductive and has good wettability with the molten metal, and the A vacuum degassing device characterized by being equipped with a coil.