JP3149556B2 - Method and apparatus for producing melting stock for precision casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a melting stock for precision casting and an apparatus therefor. More specifically, this invention is useful as a precision casting base material that is useful for precision casting of titanium having an active and high melting point and its alloys, which is highly efficient, has high productivity, and can reduce manufacturing costs. And a device for producing the same.

[0002]

2. Description of the Related Art Conventional general precision casting methods are:
The molten base material melted in a melting furnace such as a crucible furnace is cast into a ceramic shell mold prepared by a lost wax method or the like and solidified. This precision casting method is widely used as a method of manufacturing a product having a complicated shape because a product having excellent dimensional accuracy and a beautiful casting surface can be obtained.

However, in the case of this casting method, in particular,
If the material is an active metal, it was melted in a melting furnace.
Or when placed in a ladle, the molten metal becomes
With the difficult problem of contamination
Was. For example, taking Ti as an example, the engine engine tar
Light and hot wheels used for boosters
Machine parts requiring heat resistance are titanium or its alloy
Is manufactured by precision casting.
When the molten Ti is melted, alumina (Al) _TwoO
_Three) Reacts with ceramics such as_TwoProduces the acid
Pick up the element. And like this oxygen
If incorporated, the material properties deteriorate and the cast product becomes brittle.
become weak.

[0004] When pouring a molten metal into a mold and solidifying it, a feeder is usually used to prevent shrinkage cavities. However, since the feeder is disposable only once, the yield of the material is poor. Since a certain amount of base metal is dissolved in a large amount and then cast into a mold each time, there is a problem that the production efficiency is poor. In order to avoid a reaction with furnace ceramics, melting is often performed by arc melting using a skull furnace, but in this melting method, the temperature of the molten metal cannot be increased. If the preheating temperature of the mold is reduced in order to suppress the reaction between the mold and the molten metal under the condition where the temperature of the molten metal is low, it becomes difficult to spread the molten metal to every corner of the mold.

[0005] In order to eliminate such poor running of the molten metal, a casting method utilizing centrifugal force is known. However, not only is the equipment large-sized, the efficiency is poor, but also a cavity defect due to turbulence in the molten metal flow is liable to occur. There was a disadvantage. Therefore, the inventor of the present invention overcomes the drawbacks of the conventional precision casting technology, and can efficiently cast an active and high melting point metal such as titanium or its alloy, and achieve a high yield rate. We have already proposed a new precision casting device that can be realized.

As shown in FIG. 1, for example, this new casting apparatus includes a melting chamber (1) for melting a metal by induction heating and a casting chamber (2) containing a mold (3) for casting a molten metal. The casting chamber (2) is arranged so that the former can be slid downward and the latter can be slid laterally to connect and shut off. And the mold (3) is held in the upper part by airtightly dividing, and the snout (4) provided in the lower part of the mold (3)
The molten metal (5) in the melting chamber (1) by sliding the double cylinder
Melting chamber (1) and casting chamber (2)
And means for controlling the atmospheric gas and its pressure.

[0007] In this casting apparatus, the metal to be melted is supplied from below in the form of a base material (6) having a cross-sectional shape adapted to the inner diameter thereof, and the amount consumed by melting-casting is supplied to the base material (6). 6) Supply by pushing up. The metal heated and melted by the induction coil (7) becomes a water column of the molten metal (5) due to the repulsive force caused by the eddy current therein, and exists almost without contact with the crucible wall.

In the melting by induction heating, an arbitrary superheat can be given to the molten metal unlike a skull furnace.
When the temperature of the molten metal (5) reaches a temperature suitable for casting, the casting chamber (2) is slid with respect to the melting chamber (1) as shown in the arrangement of FIG. After that, the upper part of the casting chamber is moved downward by the above-mentioned double cylinder structure, and the snout (4) provided at the lower part of the mold (3) is immersed in the molten metal (5). Here, the gas pressure of argon (Ar) or the like in the melting chamber (1) (and the lower part of the casting chamber) and the gas pressure in the upper part of the casting chamber are controlled, and the molten metal (5) is passed through the snout (4) between the two. The molten metal (5) is transferred into the mold (3) by applying a pressure difference sufficient to wick.

Thereafter, if the upper part of the casting chamber is raised and retracted and the entire casting chamber (2) is slid laterally, the space between the melting chamber (1) and the melting chamber (1) is shut off, and the lid on the upper part of the casting chamber is opened to open the mold ( Take out 3) to obtain a casting. In the meantime, in the melting chamber (1), the metal is again melted and heated to form a molten metal for the next cycle. Needless to say, a new mold is placed in the casting room.

[0010] For example, the precision casting apparatus which can be exemplified as described above has been extremely useful for casting active titanium having a high melting point and its alloys, as a method for overcoming the drawbacks of the casting techniques. . However, although it is a precision casting apparatus having such excellent characteristics, in the subsequent study by the inventor, in order to enable low-cost production with high productivity, it is necessary to supply molten metal. With respect to the base material (6), it has been desired that the base material (6) be manufactured with higher purity, be efficiently manufactured, and be supplied stably.

The reason for this is that the melting stock of the base material (6) determines the quality in precision casting, and the production and supply thereof determines the productivity of the casting process. Also, usually, the base material (6) is manufactured by casting and casting a molten metal, but there is a limit in improving the efficiency.

Accordingly, the present invention provides a new means which can utilize the features of the new precision casting apparatus as described above and improve the production efficiency of the base stock for that purpose. The purpose is.

[0013]

That is, the present invention provides:
As a method for solving the above-mentioned problems, a method for producing a melting stock for precision casting, wherein a molten metal melted by levitation is sucked into a metal pipe in an inert gas atmosphere to produce a melting stock. I will provide a. Further, the present invention has a melting chamber and a suction chamber above the melting chamber as a device for this method, a suction pipe is vertically provided in the suction chamber, and a lower end of the pipe is connected to the molten metal in the melting chamber. The present invention also provides an apparatus for producing a melting stock for precision casting in which a molten metal is sucked into a suction pipe by bringing a molten metal into contact with a suction pipe in an inert gas atmosphere by a difference in atmospheric pressure between the melting chamber and the suction chamber.

[0014]

According to the method of the present invention for sucking molten metal into a metal pipe, a melting stock as a base material for precision casting having a predetermined diameter and length can be manufactured with high efficiency. As in the case of precision casting, contamination of surrounding impurities is effectively suppressed, and high-quality production is enabled.

Hereinafter, the present invention will be described by way of examples, and the method and apparatus of the present invention will be described in more detail.

[0016]

FIG. 2 illustrates a cross-sectional view of the apparatus for the method of the present invention. For example, as shown in FIG. 2, an apparatus for manufacturing a melting stock according to the present invention includes a melting chamber (11) and a suction chamber (1) disposed above the melting chamber (11).
2), the melting chamber (11) and the suction chamber (12)
The atmosphere is shut off and is structurally partitioned.

In the suction chamber (12), the upper end of a metal pipe (13) as a mold for suction is disposed inside, and the metal pipe (13) is vertically installed outside the suction chamber. are doing. The lower end of the metal pipe (13) is molten metal (14) that has been levitationally melted by induction heating.
Is in contact with In an apparatus having such a structure,
A pressure difference is generated in the atmosphere between the melting chamber (11) and the suction chamber (12), and the pressure in the suction chamber (12) is further reduced.
Then, the molten metal (14) is sucked into the metal pipe (13) by this pressure difference. The atmosphere in this case should be, as before, an inert gas for the metal to be cast into the melting stock, with argon being suitable for titanium and titanium alloys. There are the following various modes for giving the pressure difference between the atmospheric gases in the two chambers, and any of them may be adopted.

A) The dissolution chamber (11) has a substantially atmospheric pressure, and the suction chamber (12) has a pressure of 50 to 760 Torr.
r low pressure; b) the pressure inside the melting chamber (11) is lower than atmospheric pressure;
The pressure in the suction chamber (12) is even lower, c) The pressure in the suction chamber (12) is substantially atmospheric pressure, and the pressure in the melting chamber (11) is higher than that, d) The melting chamber (11) Inside is a pressure higher than the atmospheric pressure,
The pressure inside the suction chamber (12) is lower than the atmospheric pressure.

When an appropriate amount of the molten metal (14) is injected into the metal pipe (13), the molten metal is solidified by holding the molten metal for a short time, so that the difference in gas pressure is eliminated. As a result, excess molten metal returns to the melting chamber (1) and is again subjected to induction heating. The metal pipe (13) is preferably a metal containing at least one component of iron or molten metal.

It is also advantageous to arrange a porous ceramic lid at the tip of the pipe (13) as a fireproof filter (15) for degassing. This is because the filter (15) functions as a stopper at the time of sucking the molten metal (14) and as a control material of the sucking speed. In fact, using the apparatus of the present invention, about 30 kg of Ti
Al was dissolved, and this was mixed with an inner diameter of 80 mm x 1000 mm.
Shut off the power immediately after sucking into the iron pipe of the book,
The iAl was solidified and removed from the furnace. At the upper end of the iron pipe, a filter made of a refractory was arranged to prevent mixing of hot water balls into the exhaust system. The melting stock thus produced was of a clean quality without contamination during melting and casting, and there was no problem in re-melting it to produce a precision casting.

[0021]

According to the present invention, as described in detail above, a melting stock useful for precision casting of metals such as titanium and its alloys having an active and high melting point can be obtained as a uniform and high-quality melting stock. It can be manufactured with high efficiency and high productivity. The manufacturing cost can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a precision casting apparatus.

FIG. 2 is a partial sectional view of the melting stock manufacturing apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting room 2 Casting room 3 Mold 4 Snort 5 Molten metal 6 Base material 7 Heater 11 Melting room 12 Suction chamber 13 Metal pipe 14 Molten metal 15 Gas refractory filter for degassing

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B22D 23/00 B22D 23/00 F

Claims (4)

(57) [Claims] 1. Inactivation of molten metal melted by levitation
A method for producing a melting stock for precision casting, wherein the melting stock is produced by sucking a metal pipe in a neutral gas atmosphere . 2. The method according to claim 1, wherein the molten metal is sucked into a metal pipe containing one or more components of iron or molten metal. 3. It has a melting chamber and a suction chamber above the melting chamber,
A suction pipe is vertically installed in the suction chamber, the lower end of the pipe is brought into contact with the molten metal in the melting chamber, and the molten metal is sucked up in an inert gas atmosphere by the difference in atmospheric pressure between the melting chamber and the suction chamber. Manufacturing equipment for melting stock for precision casting to be sucked into pipes. 4. The manufacturing apparatus according to claim 3, wherein a refractory filter for venting gas is disposed at a tip of the pipe.