Metal founding – Process – Shaping liquid metal against a forming surface
Reexamination Certificate
2002-03-15
2004-04-27
Lin, Kuang Y. (Department: 1725)
Metal founding
Process
Shaping liquid metal against a forming surface
C164S067100, C164S125000, C164S359000, C164S066100
Reexamination Certificate
active
06725900
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of deoxidation casting and a deoxidation casting machine, more precisely relates to a method of deoxidation casting, in which a molten metal left in a feeder head is properly treated, and a deoxidation casting machine capable of executing said method.
There are many kinds of ways of casting aluminum or aluminum alloy. For example, gravity casting can be executed in a simple casting die and is capable of improving quality of products. A conventional method of aluminum gravity casting will be explained with reference to
FIG. 14. A
splittable casting die
100
is made of a metal and constituted by a lower die section
102
a
and an upper die section
102
b
. A cavity
104
, in which a product will be cast, is formed between the die sections
102
a
and
102
b.
A molten metal inlet
106
, from which a molten metal, e.g., molten aluminum, is poured, the cavity
104
and a feeder head
108
, which is provided between the inlet
106
and the cavity
104
, are formed in the upper die section
102
b
. Further, air ventilation holes
110
, which discharge air in the cavity
104
when the molten metal is introduced into the cavity
104
, are also formed in the upper die section
102
b.
When the molten metal is solidified, about 3% of volume of the molten metal is contract. By the contraction of the molten metal filled in the cavity, a contracted part is formed in the cast product. In the casting die
100
shown in
FIG. 14
, the molten metal in the feeder head
108
moves toward the contracted part, by its own weight, when the molten metal in the cavity
104
is solidified. Then, the molten metal fed from the feeder head
108
fills the contracted part, so that no contracted part is formed in the cast products. Since the molten metal is supplemented from the feeder head
108
to the cavity
104
by its own weight, volume of the feeder head
108
must be great.
Fluidity of the molten metal is low in the casting die
100
, so weight of the molten metal in the feeder head
108
must be heavy. Therefore, the volume of the feeder head
108
must be great so as to compulsorily supplement the molten metal. In the case of aluminum casting, for example, aluminum is apt to oxidize, so an oxide film is formed on the surface of the molten aluminum, so that the fluidity of the molten aluminum must be lower. To improve the fluidity, lubricant is applied to inner faces of the cavity
104
.
To improve the fluidity of the molten aluminum and to cast a product having good external appearance without applying the lubricant, the inventors of the present invention invented a method of aluminum casting (see Japanese Patent Gazette No. 2000-280063). The method will be explained with reference to
FIG. 15. A
deoxidizing compound, e.g., magnesium nitride compound (Mg
3
N
2
), is introduced into the cavity
104
of the casting die
100
, then the molten aluminum or aluminum alloy is poured into the casting die
100
. The deoxidizing compound deoxidizes the oxide film formed on the surface of the molten aluminum or aluminum alloy, so that surface tension of the molten aluminum or aluminum alloy can be reduced, the fluidity thereof can be improved, and the product having no casting-wrinkles can be produced. Namely, high quality products can be cast.
The method using the deoxidizing compound is capable of improving the fluidity of the molten metal and well filling the molten metal in the cavity. The volume of the feeder head
108
can be reduced because the molten metal is capable of well filling the cavity
104
without using the weight of the molten metal in the feeder head
108
. Therefore, the volume of the feeder head
108
may be designed on the basis of the volume reduction of the solidified metal.
In the conventional casting machine, the metal solidified in the feeder head
108
is integrated with the product solidified in the cavity
104
. The metal solidified in the feeder head
108
must be cut and removed from the cast product. The removed metal will be reused as a casting material. As described above, the step of removing a disused solidified metal from the product is an essential step in the conventional method. If the volume of the feeder head
108
is great, it takes a long time to remove the disused metal. Further, energy consumption must be increased so as to melt the disused metal, which has the great volume, to reuse.
On the other hand, in the improved method disclosed in the Japanese Patent Gazette No. 2000-280063, the volume of the feeder head
108
can be designed to supplement the contracted part of the product, so the volume of the feeder head
108
can be reduced. By reducing the volume of the feeder head
108
, the volume of the disused metal is also reduced, so the disused metal can be easily cut and removed from the cast product.
However, if the volume of the feeder head
108
is too small, the contracted part is formed in the vicinity of a connecting part between the disused metal and the cast product. In some cases, the contracted part is formed in the cast product. Further, if the molten metal left in the small feeder head
108
can be removed or discharged therefrom, working efficiency of the casting can be improved.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method of deoxidation casting, in which a disused metal left in a feeder head can be easily removed from a cast product, or the molten metal left in the feeder head can be removed from the cast product so as to easily finish the cast product and reduce energy consumption of the casting work.
Another object of the present invention is to provide a deoxidation casting machine capable of executing the method of the present invention.
To achieve the objects, the present invention has following structures.
The method of deoxidation casting of the present invention comprises the steps of:
pouring a molten metal into a cavity of a casting die, which includes a feeder head provided between a molten metal inlet and the cavity; and
reacting a deoxidizing compound with the molten metal so as to deoxidize an oxide film formed on a surface of the molten metal, and
the method is characterized in,
that rate of cooling the molten metal in the feeder head is lower than that in the cavity, and
that the molten metal in the feeder head, which is not solidified, is treated when the molten metal in the cavity is solidified so as to make an outline of a cast product correspond to that of a desired product.
The deoxidation casting machine of the present invention, in which a deoxidizing compound reacts with a molten metal so as to deoxidize an oxide film formed on a surface of the molten metal, comprises
a casting die having a molten metal inlet, a cavity into which a molten metal is poured from the molten metal inlet and a feeder head provided between the molten metal inlet and the cavity, wherein rate of cooling the molten metal in the feeder head is lower than that in the cavity, and
the machine is characterized by,
means for pressing the molten metal in the feeder head, which is not solidified, toward the cavity when the molten metal in the cavity is solidified so as to make an outline of a cast product correspond to that of a desired product.
Another deoxidation casting machine of the present invention, in which a deoxidizing compound reacts with a molten metal so as to deoxidize an oxide film formed on a surface of the molten metal, comprises
a casting die having a molten metal inlet, a cavity into which a molten metal is poured from the molten metal inlet and a feeder head provided between the molten metal inlet and the cavity, wherein rate of cooling the molten metal in the feeder head is lower than that in the cavity, and
the machine is characterized in,
that a cavity constituting member of the casting die is separable from a feeder head constituting member thereof, and
that the cavity constituting member, in which the molten metal is solidified, is separated from the feeder head constituting member while the molten metal in the feeder
Ban Keisuke
Nakatani Sakuzo
Ogiwara Koichi
Sunohara Akira
Lin Kuang Y.
Nissin Kogyo Co. Ltd.
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