JP2005179735A - METHOD OF PRODUCING Mg ALLOY, AND PRODUCTION DEVICE USED THEREFOR - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing an Mg alloy for efficiently producing an Mg alloy having uniform alloy components, and to provide a device of producing an Mg alloy used therefor. <P>SOLUTION: In the method of producing an Mg alloy, to an Mg raw material in the process of heating or the molten metal M of Mg, the molten metal m of an element for an Mg alloy is added as droplets d. The production device 1 for an Mg alloy is provided with: a main melting furnace 2 melting an Mg raw material (ingot) G; an auxiliary melting furnace 6 melting the raw material of an element for an Mg alloy; and a pipe 9 for droplets communicating the auxiliary melting furnace 6 with the main melting furnace 2, and also, capable of dropping the molten metal m of the element for an Mg alloy to the main melting furnace 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing an Mg alloy for efficiently producing an Mg alloy having a uniform alloy component and an apparatus for producing an Mg alloy used therefor.

Mg (magnesium) alloy, which is lighter than Al (aluminum), is widely used in motorcycle wheels, helmets, housings such as digital cameras and notebook computers, and various automobile parts.
By the way, in order to obtain an Mg alloy having a desired alloy composition, as shown in FIG. 6, a raw material of Mg (ingot or scrap) is charged into a melting furnace 20 composed of a furnace body 21 made of iron (steel), It is heated and melted from the side of the furnace bottom 22 and the furnace body 21 with a burner (not shown), and an ingot (solid) of an alloy element such as Al is added in a range of 10 wt% or less. In addition, in place of the Al ingot, there are cases where granular and 2 wt% or less Zn or 1 wt% or less Mn is added.

As shown in FIG. 6, the opening of the melting furnace 20 is sealed with a lid 23, and air in the melting furnace 20 is degassed from the exhaust pipe 24 and an inert gas such as Ar is blown from the air supply pipe 25. The oxidation of the molten metal M is prevented.
However, when Al, Mn, Zn, or the like, which is an alloy component, is added to the molten metal M in the solid state, as shown in FIG. 6, since the above-mentioned Al has a higher specific gravity than Mg, it settles toward the furnace bottom 22. End up. For this reason, Al or the like of the alloy component is not uniformly dispersed in the molten metal M, and a long time is required for melting to obtain a required Mg alloy. In addition, in order to make the alloy components uniform, a longer time is required if a step of holding near the melting point after heating is provided.

Therefore, as shown in FIG. 7, a method of inserting the stirring blade 28 into the molten Mg M melted in the melting furnace 20 and mechanically stirring it may be considered. The stirring blade 28 is rotated by a motor or the like (not shown) while the rotating shaft 27 passes through the through hole 26 of the lid 23. By rotating the stirring blade 28, the alloy component is easily dispersed uniformly in the molten metal M, so that the manufacturing time of the Mg alloy can be shortened.
However, in the above method, since the flow rate by stirring is added to the molten metal M, impurity elements such as Fe may be mixed due to melting damage of the stirring blade 28 and the furnace body 21. In order to remove such impurity elements, it is necessary to keep the molten metal M calm for a very long time. In addition, if the sealing property between the rotating shaft 27 and the lid 23 is not sufficient, the molten Mg M is oxidized to produce MgO (non-metallic inclusions), which may be mixed.

Incidentally, the manufacturing method of Mg alloy demonstrated above is demonstrated with the graph of FIG. In order to obtain a Mg alloy of Mg-3 wt% Al, four types of melting were performed using the melting furnace 20. The first is a case in which an Al ingot is charged immediately after heating the Mg ingot, and the second is a case in which an Al ingot is charged immediately before the dissolution of Mg is completed. The first case is a case where stirring is performed using the stirring blade 28 for 5 minutes following the completion of dissolution in the first or second.
As indicated by the solid line in the graph of FIG. 8, the first and second cases without stirring did not reach the target alloy composition and took a long time.
On the other hand, in the third and fourth cases indicated by the alternate long and short dash line or broken line, the alloy composition was almost Mg-3 wt% Al immediately after the dissolution of Mg. However, in these cases, as described above, there is a possibility that Fe, MgO, and the like may be mixed in, and in order to remove them, a very long time of calming is required.

  The present invention solves the problems of the background art described above, and provides an Mg alloy manufacturing method and an Mg alloy manufacturing apparatus used therefor for efficiently manufacturing an Mg alloy having a uniform alloy component. This is the issue.

Means for Solving the Problems and Effects of the Invention

In order to solve the above-mentioned problems, the present invention is based on the result of earnest research and investigation by the inventor and adding an element of the target alloy component as droplets to the Mg raw material or molten metal. It was made.
That is, the Mg alloy production method of the present invention (Claim 1) is characterized in that the molten Mg alloy element is added as droplets to the Mg raw material immediately after heating or in the middle of heating, or to the molten Mg. And

According to this, since the element for the Mg alloy is dropped as a droplet on the Mg raw material being heated or the molten Mg, it does not settle even if the element has a specific gravity greater than Mg, such as Al. , Uniformly dispersed in the molten Mg in a relatively short time. Accordingly, it is possible to efficiently produce a Mg alloy having a uniform alloy component.
The Mg raw material includes Mg ingots and scraps of arbitrarily shaped Mg alloys. Further, the Mg raw material immediately after heating refers to the raw material in which the Mg raw material is heated, but a part of the Mg raw material is not yet melted, and is usually charged from the beginning into the main melting furnace described later. Further, the Mg raw material being heated refers to a material from which a part of the Mg raw material starts to melt to one in which the raw material is all melted and held in a molten metal state.

Further, in the present invention, the alloying element satisfies at least one of having a specific gravity greater than that of Mg and having a melting point higher than that of Mg. Item 2) is also included.
According to this, since the element for Mg alloy is melted at a predetermined temperature in advance and dropped as a droplet into the molten Mg, even an element having a higher specific gravity or a higher melting point than Mg can be reliably It can be uniformly dispersed in the molten Mg.
The alloying elements having a specific gravity greater than that of Mg include, for example, Al, Zn, Mn, Cu, Ni, Fe, etc. The alloying elements having a melting point higher than the melting point of Mg include, for example, Al, Mn, Cu, Ni, Fe, etc. are included.

Furthermore, the present invention includes a method for producing an Mg alloy, wherein the molten Mg is immediately before or immediately after all of the Mg raw material is melted (Claim 3).
According to this, since the element for Mg alloy is dripped in Mg molten metal as a droplet, it can disperse | distribute more uniformly in the said molten metal in a short time.

On the other hand, the Mg alloy production apparatus of the present invention (Claim 4) includes a main melting furnace for melting Mg raw material, an auxiliary melting furnace for melting Mg alloy element raw materials, the auxiliary melting furnace, and the main melting furnace. And a drop pipe that can drop the molten Mg alloy element into the main melting furnace.
According to this, the raw material of the element for Mg alloy can be melt | dissolved previously with an auxiliary melting furnace, and it can be dripped at the Mg raw material in the main melting furnace or the molten metal of Mg via a droplet melting pipe. Accordingly, it is possible to efficiently produce a Mg alloy having a uniform alloy component.
For the main melting furnace and the auxiliary melting furnace, for example, a burner heating, electric resistance heating, induction heating type melting furnace or the like is used.

In the following, the best mode for carrying out the present invention will be described.
FIG. 1 shows an outline of a method of manufacturing an Mg alloy according to one embodiment of the present invention and a manufacturing apparatus 1 used therefor. As shown in FIG. 1, the Mg alloy manufacturing apparatus 1 includes a main melting furnace 2 for melting an Mg ingot (raw material) G, an auxiliary melting furnace 6 for melting an Mg alloy element raw material, and a space between them. A drop pipe 9 is provided which is in communication and drops a molten metal m for Mg alloy into the main melting furnace 2.
As shown in FIG. 1, the main melting furnace 2 includes a substantially cylindrical furnace body 3 made of iron (steel), a lid 4 for closing the opening, and a burner 5 positioned below the furnace body 3. In addition, the lid 4 is for supplying an exhaust pipe and a shielding gas (not shown) (for example, a mixed gas of dry air and SF ₆ , a mixed gas of CO ₂ and SF ₆ or a mixed gas of Ar and SF ₆ ) not shown. The supply pipe penetrates and the inside of the main melting furnace 2 can be maintained in a shield gas atmosphere.

The auxiliary melting furnace 6 includes a cylindrical furnace body 8 made of iron (steel) and an induction coil (not shown) wound in a spiral shape on the outer side thereof. Further, as shown in FIG. 1, the droplet pipe 9 has a small diameter with an upper end opened at the bottom of the furnace body 8 of the auxiliary melting furnace 6 and a lower end opened above the furnace body 3 of the main melting furnace 2. This is a heat-resistant metal tube in which the through hole 10 is provided along the axial direction.
The inner diameter of the through hole 10 is set to a range (for example, 5 to 50 mm) in which the molten metal m for Mg alloy can be dropped as a droplet d. In addition, a heat-resistant sliding gate that opens and closes the through hole 10 can be disposed in the middle of the droplet pipe 9 positioned between the auxiliary melting furnace 6 and the main melting furnace 2.

Here, one form of the manufacturing method of Mg alloy in this invention is demonstrated with reference to FIG.
As shown in FIG. 1, a raw material of an element for Mg alloy, for example, an Al ingot, or Zr grains or Mn grains, is charged in advance in a furnace body 8 of an auxiliary melting furnace 6 and this is induction-heated to produce Al or the like. It is set as a molten metal. In addition, the inside of the furnace body 8 is previously set as an inert gas atmosphere.
In parallel with or after the above, a Mg ingot (raw material) G is charged into the furnace body 3 of the main melting furnace 2, the inside of the furnace body 3 is sealed with a lid 4, and the inside of the furnace body 3 is sealed with the shielding gas. After making the atmosphere, the furnace body 3 is heated by the burner 5 to gradually dissolve the ingot G in the molten metal M as shown in FIG.

  The molten metal m such as Al in the auxiliary melting furnace 6 is dropped as a droplet d through the droplet pipe 9 to the Mg ingot G and the molten Mg M immediately after heating or in the middle of heating. Then, the molten metal m such as Al is mixed into the molten Mg M staying at the bottom of the furnace body 3, but is uniformly dispersed in the molten metal M without being immediately settled. As a result, it is possible to obtain a Mg alloy having a uniform alloy component in the vicinity of the time when a required amount of molten metal m such as Al is dropped and all the Mg ingot G is melted to form molten metal M. The Mg alloy is tilted in the main melting furnace 2 and poured into an ingot case to be described later, thereby forming an Mg alloy ingot having a uniform alloy component.

  FIG. 2 is a schematic view showing a manufacturing method of different forms of Mg alloys using the manufacturing apparatus 1. In the same manner as described above, an Al molten metal m is prepared in the auxiliary melting furnace 6. In parallel or in advance, Mg ingot (raw material) G is charged into the furnace body 3 of the main melting furnace 2, and almost the entire amount of the ingot G is melted in the same manner as described above. As shown in FIG. At this time, the molten Al m in the auxiliary melting furnace 6 is dropped into the molten Mg M in the main melting furnace 2 as droplets d through the droplet melting pipe 9. In this case, since the Al molten metal m is immediately and uniformly dispersed in the molten metal M, a predetermined Mg alloy can be obtained in the shortest time.

Now, specific examples of the present invention will be described.
In order to produce 10 kg of Mg-3 wt% Al alloy, three sets of Mg ingots G were individually charged in the main melting furnace 2 of the production apparatus 1 and heated.
On the other hand, three sets of required amounts of Al ingots were individually melted in the auxiliary melting furnace 6 and immediately after heating the Mg ingot G (heating start to 15 minutes: addition time 1), during heating (after 30 minutes of heating) 15 minutes from the addition time 2), or immediately after the completion of melting (15 minutes after 45 minutes of heating: addition time 3), the molten Al m is passed through the droplet pipe 9 into the molten Mg M. The solution was dropped for each set of Examples.
The heating time and the Al content in the molten Mg alloy were measured by sampling for each group of the examples (addition time 1, 2 and 3). The results are individually shown in the graph of FIG. 3 by a solid line, a chain line, and a broken line.

According to the graph of FIG. 3, the set of addition time 1 indicated by a solid line changes at an alloy composition of Mg-2.8 wt% Al after about 45 minutes have passed since the start of heating of the Mg ingot (Mg dissolution completed). In addition, the group of addition time 2 indicated by the alternate long and short dash line changed with the alloy composition of Mg-3 wt% Al after about 50 minutes from the start of heating. Further, the set of addition time 3 indicated by a broken line has an alloy composition of Mg-3 wt% Al when the entire amount of Al molten metal m has been dropped, that is, when about 60 minutes have elapsed since the start of heating.
Incidentally, in the group using the conventional method shown in the graph of FIG. 8 and without stirring, the alloy composition level of Mg-2.5 wt% Al has been reached even when about 80 minutes have elapsed since the start of heating of the Mg ingot. There wasn't. Moreover, in the stirred group, when about 50 minutes passed from the start of heating, the alloy composition was almost Mg-3 wt% Al. Processing was necessary.
From the results of the three sets of examples as described above, the effect of the manufacturing method of the Mg alloy of the present invention is supported, and the superiority thereof can be easily understood. Even when the molten Al m is dropped in the time period between the addition time 1 and the addition time 2, it is possible to obtain the same effects as in the above embodiments.

Immediately after the completion of melting of the Mg ingot G (15 minutes after 45 minutes of heating: addition time 3) in order to produce 10 kg of Mg-3 wt% Al alloy using the production apparatus 1, the auxiliary melting furnace 6 The molten Al m dissolved in (1) was dropped into the molten Mg M via the droplet pipe 9 as droplets. After the elapse of 60 minutes from the start of heating, the molten Mg alloy M1 (10 kg) of the obtained example was tilted to 90 degrees to the furnace body 3 of the main melting furnace 2 as shown in FIG. Hot water was poured into the ingot case (mold) 12.
On the other hand, Mg ingot G was charged into the melting furnace 20, and Al ingot was charged into this (addition time 1), and these were heated and melted. A molten alloy (10 kg) was obtained. The molten metal was poured into the ingot case 12 in the same manner as shown in FIG.

For the Mg alloy ingot 14 of the obtained example and the Mg alloy ingot of the comparative example, samples were cut out at each of the top, middle, and bottom positions in the height direction shown in FIG. The content of was measured. The results are shown in the graph of FIG.
According to the graph of FIG. 5, in the ingot 14 of the example, the Al content was uniform at about 3 wt% at each of the top, middle, and bottom positions. This is because, in the example, since the molten Al m was dropped into the molten M M, Al was uniformly dispersed throughout the ingot 14.

On the other hand, the Mg alloy ingot of the comparative example has segregated Al content such that Al: 4.2 wt% at the top, Al: 2.1 wt% at the middle, and Al: 1.3 wt% at the bottom. It was. This is because Al having a larger specific gravity than Mg settled near the furnace bottom 22 of the melting furnace 20, so when pouring into the ingot case 12, the part becomes a metal structure near the top of the Mg alloy ingot, and Al This is because the metal structure near the bottom is near the liquid surface of the molten metal.
The effect of the Mg alloy production method of the present invention is supported by the Mg alloy ingot 14 of the embodiment as described above, and its superiority will be easily understood.

The present invention is not limited to the above-described embodiments and Examples 1 and 2.
For example, Sn, Zr, Ag, Ce, Th may be used as the element for Mg alloy, Be having a specific gravity equivalent to Mg and having a high melting point, or K having a lower specific gravity and lower melting point than Mg. Na, Li may be used.
Further, the element for Mg alloy can be dropped as a droplet, and a part thereof can be added to the Mg melt in the form of particles or powder.
Furthermore, in the manufacturing apparatus 1, the main melting furnace 2 and the auxiliary melting furnace 6 may be set inside a common sealed container so that the inside of the container can be replaced with an inert gas atmosphere.
The present invention can be modified as appropriate without departing from the spirit of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows 1 form of the manufacturing method of Mg alloy of this invention, and the manufacturing apparatus used for this. Schematic which shows the manufacturing method of Mg alloy of a different form. The graph which shows the relationship between the heating time of Mg of the Example in the manufacturing method of this invention, and the dissolution amount of Al in the molten metal of Mg alloy. Schematic which shows the state which uses the molten metal of Mg alloy of an Example as an ingot. The graph which shows content of Al in each site | part in the ingot of the Mg alloy of an Example and a comparative example. Schematic which shows the manufacturing method and manufacturing apparatus of the conventional Mg alloy. Schematic which shows the manufacturing method and manufacturing apparatus of the conventional Mg alloy of a different form. The graph which shows the relationship between the heating time of Mg of the Example in the conventional manufacturing method, and the amount of dissolution of Al.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus of Mg alloy 2 ... Main melting furnace 6 ... Auxiliary melting furnace 9 ... Pipe for droplet G ... Mg ingot (Mg raw material)
M ... Mg molten metal m ... Al molten metal (Mg alloy element molten metal)
d: Droplet

Claims (4)

Add molten Mg alloy element as droplets to Mg raw material immediately after heating or in the middle of heating, or molten Mg,
The manufacturing method of Mg alloy characterized by the above-mentioned. The alloying element satisfies at least one of having a specific gravity greater than that of Mg and a melting point higher than that of Mg.
The manufacturing method of Mg alloy of Claim 1 characterized by the above-mentioned. The molten Mg is immediately before or immediately after all of the Mg raw material is dissolved,
The manufacturing method of Mg alloy of Claim 1 or 2 characterized by the above-mentioned. A main melting furnace for melting the Mg raw material;
An auxiliary melting furnace for melting the raw material of the element for Mg alloy,
A droplet pipe that communicates between the auxiliary melting furnace and the main melting furnace and that can drop the molten Mg alloy element into the main melting furnace.
An apparatus for producing an Mg alloy characterized by the above.

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