Metal founding – Process – Shaping liquid metal against a forming surface
Reexamination Certificate
1999-06-21
2001-11-06
Nguyen, Nam (Department: 1722)
Metal founding
Process
Shaping liquid metal against a forming surface
C164S255000
Reexamination Certificate
active
06311758
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 10-174281 filed on Jun. 22, 1998 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a suction casting method and a suction casting apparatus.
2. Description of the Related Art
Conventionally, there is known, for example, an automotive wheel suction casting apparatus by means of a suction casting method for sucking molten metal from the pouring gate of a die into a cavity by the application of negative pressure, which structure is shown in
FIGS. 6 and 7
.
The structure is as follows. A lower surface plate
102
is provided at the upper portion of a temperature holding furnace
101
and a furnace-side pouring gate
103
is provided at the surface plate
102
. A die
105
provided with a die-side pouring gate
104
communicating with the furnace-side pouring gate
103
, is placed on the lower surface plate
102
. A chamber
106
and an upper chamber
107
surround the outer periphery of the die
105
. The pressure of interiors of the chambers
106
and
107
is reduced by a suction pump
108
(i.e., negative pressure is applied to the suction pump
108
). Pressure P
1
is applied to the interior of the cavity
112
equally through a clearance D
1
between a side die
109
and an upper die
110
and a clearance D
2
between the upper die
110
and a release pin
111
, to thereby reduce the pressure of the interior of the cavity
112
. Molten metal
113
within the temperature holding furnace
101
is sucked and filled into the cavity
112
through the furnace-side pouring gate
103
and the die-side pouring gate
104
.
An upper surface plate
114
is fixedly attached to the lower surface plate
102
. The upper chamber
107
and the upper die
110
are ascended and descended by being driven through a movable surface plate
116
by a hydraulic cylinder
115
disposed at the upper surface plate
114
.
Also, there is provided suction means
118
for applying higher negative pressure than that of the interior of the cavity
112
to the abutment surface
117
between the furnace-side pouring gate
103
and the die-side pouring gate
104
using the suction pump
108
, to thereby inhibit inflow of air from the abutment surface
117
into the pouring gates. The technique as described above is disclosed by, for example, Japanese Patent Publication No. 3-7465.
Meanwhile, the phenomenon of misrun occurs to a low temperature portion of the die stated above. As for the die
105
, for example, short-run occurs to the surface portion of the upper die
110
lower in temperature than the side die
109
compared with the surface portion of the side die
109
. Then, a space A is generated between the surface portion of the upper die
110
and a product
119
as shown in FIG.
7
. As a result, the space A serves as an insulating layer to thereby cause casting defect (shrinkage) B shown in FIG.
7
.
Furthermore, as stated above, even if applying high negative pressure to the abutment surface
117
, the overall interior of the cavity
112
has the same pressure. Due to this, the air within the space A thus generated cannot be drawn out and removed, thereby causing casting defect B stated above as well.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a suction casting method and a suction casting apparatus capable of inhibiting occurrence of the above space A and inhibiting occurrence of casting defect.
To achieve the above object, the present invention is a suction casting method for pouring molten metal from a pouring gate of a die into a cavity using negative pressure, wherein higher negative pressure than negative pressure of an interior of the cavity is applied to a low temperature surface portion of the die.
According to the present invention, by applying higher negative pressure than the negative pressure of the interior of the cavity to the low temperature surface portion, molten metal is well run at the surface portion to thereby inhibit air from remaining at the surface portion. Accordingly, inhibiting occurrence of the space at the surface portion and inhibiting occurrence of casting defects such as shrinkage cavity are achieved.
Moreover, the present invention in another aspect is a suction casting apparatus for pouring a molten metal into a cavity from a pouring gate of a die using negative pressure includes a first suction means for applying the negative pressure to an interior of the cavity and a second suction means for applying higher negative pressure than negative pressure of the interior of the cavity to a lower temperature surface portion of the die.
The apparatus of the present invention can achieve the method of the first invention.
Furthermore, the present invention in another aspect is a suction casting method including steps of forming a bottomed cavity out of a lower die, a side die and an upper die fitted into the side die, providing a suction port between the side die and the upper die, applying negative pressure from the suction port to an interior of the cavity and pouring molten metal into the cavity using the negative pressure includes a suction port other than the suction port is provided at a portion of the upper die at which an upper end of the cavity is formed, higher negative pressure than the negative pressure of the interior of the cavity being applied from the suction port to a side peripheral surface portion of the upper die.
According to the present invention, in case of, for example, the apparatus including an annular cavity for forming an automotive wheel using a lower die, a side die and an upper die, high negative pressure is applied to the low temperature surface portion of the upper die, thereby making it possible to inhibit occurrence of casting defect by the same function as that of the first invention.
The present invention in another aspect is a suction casting apparatus includes a bottomed cavity is formed out of a lower die, a side die and an upper die having a portion fitted into the side die and a peripheral protrusion protruding from the portion; a first suction port communicating with the cavity, is formed between the side die and the peripheral protrusion of the upper die; a release pin insertion hole communicating with the cavity is formed at the peripheral protrusion of the upper die forming an upper end portion of the cavity, a release pin inserted into the release pin insertion hole, a clearance formed between the release pin insertion hole and the release pin, the clearance serving as a second suction port; a first chamber communicating with the first suction port is provided outside the side die; a second chamber communicating with the second suction port is provided on the upper die; and a vacuum unit for applying negative pressure to an interior of the first chamber and an interior of the second chamber so that negative pressure of the interior of the second chamber is higher than negative pressure of the interior of the first chamber.
The present invention in another aspect is a suction casting apparatus includes a bottomed cavity is formed out of a lower die, a side die and an upper die having a portion fitted into the side die and a peripheral protrusion protruding laterally from the portion; a first suction port communicating with the cavity is formed between the side die and the peripheral protrusion of the upper die; a plurality of vent holes communicating with the cavity are formed at the peripheral protrusion of the upper die forming an upper end portion of the cavity, and sintered metal having permeability is arranged at a lower end of the vent holes, thereby forming a second suction port; a first chamber communicating with the first suction port is provided outside the side cavity; a second chamber communicating with the second suction port is provided on the upper die; and a vacuum unit applying negative pressure to an interior of the first chamber and an interior of
Masuda Ryuuichi
Sakabe Haruyuki
Sawada Tomokazu
Urusidani Hiroyuki
Central Motor Wheel Co., Ltd.
Del Sole Joseph S.
Nguyen Nam
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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