JPH11347706A - Differential pressure casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a differential pressure casting method which can be economically executed respectively under pressurization and under reduced pressure to a high m.p. material and a differential pressure casting apparatus which can apply to the high m.p. material and effectively performs by providing a sprue part which can durably be used, and using a stable molten surface detecting sensor having the durability. SOLUTION: This differential pressure casting method is composed of the processes, in which a mold 3 and the sprue part 1 are mated with a molten metal running part, the sprue part 1 is inserted in the opening part above the molten metal in an air-tight furnace body and projected in the inner part of the furnace body and dipped into a prescribed depth in the molten metal 4, a cavity is filled with the molten metal 4 3-3 by pressurizing the air-tight furnace, when the molten metal in the sprue part 1 and a mating part of the mold body reaches to about >=40% solid phase ratio, the mold body is separated from the sprue part 1 and shifted to the mold opening process outside of the furnace, the sprue part 1 is separated from the air-tight furnace body, the solidified molten metal 4-1 in the sprue part 1 outside of the furnace is pushed out to the molten metal immersion end side and removed, and subsequently, the mold body is prepared to the following casting by setting the mold body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure casting method and an apparatus for performing differential pressure casting of a high melting point material such as an iron-based material without using a stalk.

[0002]

2. Description of the Related Art Differential pressure casting, in which molten metal is filled into a mold by depressurization or pressurization, is capable of controlling the filling, and is suitable for casting high-quality products. For low melting point alloys such as aluminum, differential pressure casting has been used as the main casting method for producing components with complex shapes such as cylinder heads. However, for high melting point materials such as iron-based materials, although a method utilizing reduced pressure has been proposed, its practical application is limited. For cast iron having a relatively low melting point, siphon casting using a large pressurized holding furnace is used.

[0003]

However, the conventional method and apparatus for differential pressure casting of a high melting point material have the following problems.
Conventionally, in the application of differential pressure casting to an iron-based high melting point material, there is no durable hot water supply pipe connecting the mold and the molten metal container, and there is only a consumable one that is replaced every time. For this reason, the application of the differential pressure casting to the pressurization type using an airtight furnace body has not been observed, and it has been applied only to the reduced pressure type that can be implemented only by sealing the mold. In addition, it is practical to immerse a mold gate of a sand mold or the like directly in a molten metal to perform casting under reduced pressure. Even in this case, the sprue is large compared to the normal shape due to immersion, and is consumed each time. Therefore, the cost is high. In addition, since the sand mold is air permeable and entraps air at the time of casting, the molten metal is immersed. Sometimes there was a problem such as sand falling. In addition, in the case of a large and high cast product, the decompression method has a problem such as generation of gas defects due to high decompression. Also,
In the case of spheroidal graphite cast iron or the like containing Mg, there is also a problem such as coarsening of graphite due to reduced pressure. For cast iron, there is an example of siphon-type pressure casting.However, in order to prevent solidification of the molten metal in the equipment, the hot water supply section needs to have a large diameter and holds unnecessary molten metal, and keeps the hot water supply system warm. There are many practical problems, such as the necessity of an apparatus and the removal of a solidified film at rest. Furthermore, it was impossible to apply to a casting line having a high melting point. An object of the present invention is to provide a differential pressure casting method for economically performing differential pressure casting of a high melting point material for each of pressurization and decompression, to provide a gate portion that can be used in a durable manner, To provide a pressure-type differential pressure casting apparatus applicable to the present invention, and to provide a pressure-type differential pressure casting apparatus that implements the present invention more effectively by using a durable and stable liquid level detection sensor. is there.

[0004]

The present invention to achieve the above object is as follows. (1) The mold body and the sprue are aligned in the molten metal passage, and the sprue is inserted into an opening above the molten metal of the hermetic furnace, and the spout is projected into the furnace body. The surrounding portion is airtightly contacted, and the gate portion and the molten metal of the high melting point material are relatively moved to immerse the gate portion to a predetermined depth in the molten metal,
The molten metal is filled into the cavity in the mold body by pressurizing the inside of the airtight furnace, and the molten metal in the sprue part and the joint part of the mold body is separated from the sprue when the solid phase ratio is about 40% or more,
Moved to the mold opening process outside the furnace, the gate section is separated from the airtight furnace body, the solidified molten metal of the gate section is extruded from the mold body joint side to the molten metal immersion end side outside the furnace and removed, and the gate section is placed on the furnace. A pressurized differential pressure casting method comprising the steps of returning, and then setting the mold body to prepare for the next casting. (2) The mold body and the sprue are joined together in the molten metal passage, and the mold body is air-tightly covered with an outer package except for the sprue opening.
The gate is immersed in the molten metal to a preset depth, the airtight outer casing is decompressed, and the molten metal is filled into the cavity in the mold body.
When it reaches 0% or more, the mold body is separated from the sprue, and the mold body is moved to the mold opening process outside the furnace, and the sprue is separated from the furnace and moved out of the furnace, and the mold body joining surface Depressurized differential pressure casting consisting of removing the solidified molten metal at the gate from the side by pushing it out to the molten metal immersion side, returning the gate to the furnace, setting the mold body on the gate and preparing for the next casting Law. (3) An airtight molten metal holding container having a heating element inside, and an airtight lid thereof, and an airtight elastic member such as a bellows or a sliding seal portion on the airtight lid which can be moved up and down. A mold receiver having an opening having a sealing surface in a peripheral portion, a liquid level detection sensor of a molten metal constituted by electrodes or optical means connected to the mold receiver, and an upper and lower part of the mold receiver constituted by a cylinder or the like. A drive unit, a control panel of an up-down drive unit connected to the liquid level detection unit, an airtight furnace pressure control unit connected to the liquid level detection sensor, and a unit for detaching a mold from the mold receiver. Pressure differential pressure casting equipment. (4) The gate section has one or a plurality of through-holes, and the upper side of the through-hole can be connected to the cavity of the mold body, and has a cross-sectional shape in which the internal vertical cross-sectional shape can be drawn downward without interference, Further, at least the outer shape of the molten metal immersion portion is reduced as it goes downward, the outer shape of the vertical cross section is shaped to be pulled down without interference, and at least the molten metal contact portion has a cavity in which a cooling medium can be fluidly present, A metal member having a connection port between the outside and the cavity and having a sealing portion surrounding the opening on the upper surface or an overhanging portion having a sealing portion having a larger outer shape than the molten metal immersion portion on the lower surface, and of the same type as the molten metal or a low melting point metal member , A ceramic member having a thermal conductivity equivalent to that of a metal,
Alternatively, the pressure-type differential pressure casting apparatus according to (3), wherein the apparatus is made of an airtight high heat conductive material such as a graphite member. (5) The liquid level detection sensor comprises a detector that detects that the gate is immersed in the molten metal when the pressure difference between the pressure in the airtight part of the mold and the furnace and the atmosphere is equal to or higher than a predetermined value. ).

In the above methods (1), (2), and (3), the most suitable casting method is provided by freely selecting pressure reduction or pressure depending on the type of product. After casting, the mold (also called a mold) and the sprue are separated, the mold is removed, and the sprue is cleaned, so that the sprue can be used repeatedly without using a molten metal hot water supply pipe, which makes it economical. In particular, the differential pressure casting can be performed on an iron-based high melting point material. The pressure-type differential pressure casting apparatus of the present invention can be applied to general molds other than the above-mentioned gate section, and enables casting of cast steel or the like with a low quality of casting similar to that of aluminum and the like. In addition, since the gate section can be inserted into the furnace by the gate receiver, it is possible to use a crucible type induction furnace which is optimal for iron-based molten metal, and a compact apparatus having only the furnace in an airtight structure has been made possible. Further, the path of the molten metal to the cavity is short, so that heat loss can be minimized, and the castability is improved. Further, since the mold body is separated when the solid phase ratio reaches about 40% or more, the solidified material of the molten metal does not fall into the molten metal, and there is no adverse effect on the product quality. In addition, the gate section of the above (4) forms a solidified film on the contact surface early even with a high melting point molten metal such as an iron-based material, thereby preventing direct contact with the molten metal and at the same time, the contact section on the side of the gate section. Is maintained at a low temperature equal to or lower than the melting point of the material of the sprue, thereby preventing thermal damage and erosion of the sprue by the molten metal. In addition, the contact portion has an integral structure, thereby preventing mechanical damage. As a result, it is possible to realize a durable gate for an iron-based molten metal, which has not been conventionally provided. In addition, the gate section acts as an element of the airtight space required for differential pressure casting,
The occurrence of defects due to pressure leakage is prevented. The device (5) provides a liquid level detection method that captures the characteristics of the closed space,
Durable and stable control is enabled. As described above, differential pressure casting can be applied stably and economically to a wide range of iron-based products.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A differential pressure casting method and apparatus according to a preferred embodiment of the present invention will be described. 1 to 7 show a reduced pressure differential pressure casting apparatus according to the present invention and steps of a reduced pressure differential pressure casting method performed by using the apparatus. In FIG. 1, the sprue 1 is provided with an overhang 1-7 projecting radially outward from the sprue 1-1, the upper surface of the sprue 1-1 being flat, and the opening 1-2.
Are disposed around the upper surface of the seal member. The opening 1-2 widens in cross section as it goes down, and has a shape in which the vertical cross section comes out without interference. In addition, the outer shape of the sprue 1-1 becomes narrower as it goes downward, and the vertical cross-sectional shape has a shape that can be pulled down without interference. The sprue 1-1 has a space 1-3 for holding a cooling medium such as water therein, and the space 1-3 passes through a connecting conduit 1-31 and is constituted by a sprue portion (not shown) or the like. The holding unit 1-6 of the lifting / lowering mechanism communicates with an external supply source and a discharge destination. Also,
Since the molten metal contact portions of the gate 1-1 and the opening 1-2 have an integral structure, there is no gap at the joint.

The liquid level detection sensor 2 has a detection electrode 2
−1, and the output of the liquid level detection sensor 2 is output to a control panel of a gate member moving mechanism (not shown). Mold 3
Is composed of a lower mold 3-1 and an upper mold 3-2, and forms a product cavity 3-3. The cavity 3-3 is opened to the outside at a gate 3-4 provided at the center of the lower mold 3-1. 3-5
Is a seal member composed of an O-ring or the like,
1. Hermetically seal the parting surface of the upper mold 3-2. A vent 3-6 provided in the upper part of the cavity 3-3 is a vent composed of fine holes and the like, and a decompression hole 3-61 provided in the center of the upper mold 3-2, and an upper part of the upper mold 3-2. Via a decompression hose 3-62 connected to a decompression device including an external vacuum pump (not shown). Reference numeral 3-7 provided on the lower surface of the lower mold 3-1 is an airtight seal groove. Further, the mold 3 is held by a detachment mechanism (not shown), and can be moved up and down and moved. In the following figures, only the numbers related to the steps are shown. The same numbers indicate the same contents. In FIG. 2, reference numeral 4 denotes a molten metal in a furnace such as a holding furnace having heating means (not shown). In FIG. 4, 4-1 existing inside the cavity 3-3 and around the gate 1-1 indicates solidified molten metal. FIG.
, 5 indicates a solidified product. In FIG. 6, 6
Is a residual hot water removing device, and the residual hot water removing device 6 is provided outside the furnace, and includes a drain pin 6-1 and a gate holder 6-2 connected to driving means such as a hydraulic cylinder (not shown).

Next, the operation of the reduced pressure differential pressure casting apparatus and the operation of each step of the reduced pressure differential pressure casting method will be described with reference to FIGS. In FIG. 1, the mold 3 is a lower mold 3-1;
The upper mold 3-2 is mated, and the parting surface is sealed with a sealing member 3-
5, whereby the cavity 3-3 is hermetically sealed from the atmosphere except for the gate 3-4. The mold 3 is brought into close contact with the gate 1 without any gap. At this time, the gate 3
The lower mold 3-1 and the upper surface of the gate 1 are sealed with a sealing member 1-4. Further, at this time, the space 1-3 of the gate section 1 is supplied with water as a cooling medium from the holding material 1-6. The entirety is lowered by the gate-portion elevating mechanism, and as shown in FIG.
1 is dipped. The detection electrode 2-1 touches the molten metal 4, the liquid level detection sensor 2 detects the molten metal surface, and the descent is stopped. The opening 1-2 of the gate is sealed from the atmosphere by the molten metal 4,
Form an airtight space inside. By operating a pressure reducing device (not shown in FIG. 3), the pressure inside the cavity 3-3 is reduced through the pressure reducing hose 3-62, the pressure reducing hole 3-61, and the vent 3-6, and the molten metal 4 is sucked into the cavity 3-3 and filled. I do. FIG.
Indicates a change in the pressure in the mold at that time.

As shown in FIG. 4, water and the like are passed through the space 1-3 and the connecting conduit 1-31 inside the gate section 1.
The gate 1 is thereby cooled, and a solidified film 4-1 is formed in the molten metal immersion portion of the gate 1-1. Moreover, the temperature of the molten metal contact portion of the gate section 1 is kept below the melting point of the gate section 1 by vigorous cooling. The molten metal solidifies inside the mold 3 as well. In FIG. 5, only the mold 3 is raised when the molten metal in the gate section has a solid phase ratio of about 40% or more, and the filled molten metal is divided at the boundary between the mold 3 and the gate section 1. Opening 1 of the gate 1
The solidification of the molten metal in -2 proceeds.

Next, the gate section 1 is detached from the molten metal 4, taken out of the furnace, set in the residual hot water removing device 6 as shown in FIG. 6, held in the gate receiver 6-2, and removed with the pin 6-1. The remaining solidified water 4-1 is extruded downward and removed. Since the shape of the gate 1 is as described above, even if the molten metal in the gate opening 1-2 is completely solidified, it can be extruded without being hindered by the gate 1. The mold 3 is also opened up and down as shown in FIG. 7, and the solidified product 5 is taken out. The gate section 1 returns to the position of FIG. 1 for the next casting, and the entire process is completed.

The immersion depth of the gate section 1 is set in advance by an experiment or the like in order to secure the sealing action by the molten metal. The separation in FIG. 5 is also set in advance by experiments or the like based on the elapsed time from casting.
In the present embodiment, the gate section 1 and the mold 3 are both made of a copper alloy. The molten metal 4 is a cast stainless steel material, and the molten metal temperature is about 1550 ° C.
Thus, a large number of small parts with a total casting amount of about 3 kg were cast.
The immersion depth of the gate 1 is expected to decrease the level of the molten metal after casting.
The sprue member 1 and the mold 3 were separated 5 seconds after casting. When the solid phase ratio is 40% or more, the molten metal does not drop.

The gate section can be made of another metal material, and it is preferable to use a material having a good cooling effect and a high thermal conductivity. A material having a relatively low thermal conductivity is designed to have a small thickness. Is also good. Further, a ceramic or graphite material which can be cooled may be used. In addition, in this embodiment, the gate part 1 was coated with a graphite-based release material before casting, but was effective in removing the residual hot water shown in FIG. The immersion in the molten metal may be fixed at a fixed value as in the present embodiment, or may be lowered in accordance with a decrease in the level of the molten metal during casting. Further, in this embodiment, the decompression is performed by maintaining the airtightness of the mold itself. However, an airtight chamber that entirely covers the entire mold may be used. In the present embodiment, the mold is cooled outside the furnace for each casting, but a cooling path may be provided in the mold to apply water cooling or the like.

FIGS. 8 and 9 show another embodiment (a plurality of gate portions 1 ', 2) in the gate portion of the reduced pressure differential pressure casting method and apparatus.
1 (a) is a plan view showing a gate section in which 1 ″ is integrated.
7 to 7 indicate the same contents as those in FIGS. 1-
Reference numerals 311, 1-312 denote cooling medium introduction holes and cooling medium introduction holes, respectively. Illustration of mounting bolts and the like is omitted. FIG. 9 is a sectional view taken along line AA of FIG. The shape is the same as the description of FIG.

FIG. 11 shows an apparatus of an embodiment in the pressure differential pressure casting. 1 to 7 indicate the same contents as those in FIGS. Reference numeral 1-5 denotes an airtight joint surface provided on the lower surface of the overhang portion 1-7 of the gate section 1. The mold 3 is vertically divided and includes left and right molds 3-1 ′ and 3-2 ′. 3-7
Is a detachable member of the mold 3, and is connected to a lifting / lowering moving mechanism constituted by a cylinder or the like (not shown). The airtight container 9
An induction furnace body 10 composed of an induction coil 10-2, an inductor composed of an iron core, and a crucible 10-1 is incorporated. 9-1 is an airtight flange, and 9-10 is a closed space. Pressurized gas introduction hole 9 provided in a part of airtight container 9
-2 is connected to a pressurized gas hose 9-3, and the side of the pressurized gas hose 9-3 not connected to the pressurized gas introduction hole 9-2 is connected to a pressurized gas source (not shown). Not connected via a pressure control device. Reference numeral 8 on the upper surface of the airtight container 9 denotes an airtight lid, which has an opening 8-1 at the center in the left-right direction, so that the mold receiver 7 can be airtightly and slidably inserted. The mold receiver 7 can be moved up and down by a driving means such as a cylinder (not shown) with respect to a support 8-2 fixed to the airtight lid 8 by a bearing 7-3. Mold receiving 7
Has an opening 7 at the lower end into which the gate 1-1 of the gate 1 can be inserted.
−1, and has an airtight joint surface 7-2 around it. In addition, the outer diameter of the mold receiver 7 can be inserted into the crucible 10-1.

Next, the method of the embodiment in the case of the pressure type will be described. FIG. 11 shows the mold set before casting. The mold 3 is different from the decompression type,
The parting surfaces 1 ′ and 3-2 ′ are not sealed, the cavity 3-3 communicates with the atmosphere through the parting gap, and the mold 3 and the gate are set when the gate 1 is set. Part 1
There is no seal on the joint surface with. The gate 1 is provided with a mold receiver 7.
Is set in the mold receiver 7 by inserting the gate 1-1 into the opening 7-1. At this time, the hermetic bonding surface 7-2 around the opening 7-1 and the hermetic bonding surface 1-5 on the lower surface of the overhang portion 1-7 are in airtight contact. In this embodiment, only the machined surface is used, but an elastic seal member may be used. As a result, a closed space 9-10 is formed by the lid 8, the mold receiver 7, and the gate section 1 of the airtight container 9. However, the closed space 9-10 is in communication with the atmosphere via the gate opening 1-2 of the gate 1 and the cavity 3-3. Cooling water or the like is supplied to the gate 1 via a holding member 1-6, and the cooling water or the like is discharged from another holding member 1-6. Desorption device 3-
7 is lowered in a state where the mold 3, the gate section 1, and the mold receiver 7 are in close contact with each other. The liquid level detection sensor 2 'comes into contact with the molten metal 4, detects the liquid level of the molten metal, and stops at a predetermined immersion depth. After the gate section 1 enters the molten metal 4, the airtight container 9, the airtight lid 8, the gate section 1
Thus, a closed space 9-10 is formed.

A pressurized gas is supplied to the closed space 9-10 through a pressurized gas hose 9-3 and a pressurized gas introduction hole 9-2, and the molten metal 4 is supplied from the gate 1 to the cavity 3-3. Push up and fill. FIG. 12 shows the rise in the furnace pressure at this time. Also at this time, a solidified film is formed early on the gate 1 due to the internal water cooling effect and high thermal conductivity, and the temperature of the molten metal contact portion of the gate 1 is kept at a low temperature equal to or lower than the melting point of the gate 1. It is.

When the molten metal at the boundary between the gate section 1 and the mold 3 has a solid phase ratio of about 40% or more, the desorption device 3-7 is raised,
The mold 3 and the gate section 1 are separated, and the solidified molten metal inside is separated. The mold 3 is released from the outside and the product 5 is taken out. After separation,
The spout 1 is raised by the holding member 1-6 and taken out to the outside, and the remaining solidified hot water is pushed down and removed as in FIG. The mold receiver 7 also rises and returns to a position outside the induction furnace.
If the gate section 1 is set in the mold receiver 7 again, the next casting becomes possible. Pressurization of the furnace is released when the mold 3 and the sprue 1 are separated. In the pressurized type, the furnace 10 may be moved up and down in the hermetic container 9, but the capacity of the closed space 9-10 becomes large and controllability deteriorates. In addition, induction heating is effective for iron-based materials, and a crucible-type induction furnace is optimal. In order to prevent induction heating of the airtight container 9, an inductor containing a core was used.
In this embodiment, a cast steel part of about 1000 mm was manufactured which is difficult to apply due to gas defects and the like in the decompression method because of the pressurization method. Mold 3
Is a copper alloy as in the case of the decompression type, and the gate 1 is also made of the same material. The seal between the mold receiver 7 and the airtight lid 8 may be made of an airtight elastic member such as a bellows.

Further, in the apparatus of this embodiment, it is possible to perform a pressure-type differential pressure casting of an iron-based material, which has never been achieved in the past. In addition, a consumable sand mold can be used as long as the mold has a gate that enters the mold receiver 7 and enters the opening 7-1. Further, a configuration in which a sand mold and a mold are mixed may be used. Also crucible 10
In this case, the mold receiver 7 is inserted into -1, so that the distance between the molten metal 4 and the mold 3 can be shortened. The other embodiments of the gate section shown in FIGS. 8 and 9 are also applicable to the case of the pressurized type. For pressurization, the seal 1-4 on the upper surface is unnecessary, and an airtight joint may be installed on the lower surface of the overhang portion 1-7 in accordance with the mold receiver 7.

In the above-described embodiment, the detection of the liquid level of the molten metal is carried out by a contact type such as an electrode, but there is a problem in durability. In both the pressurizing and depressurizing methods, when the gate comes into contact with the molten metal, an airtight space is formed in the furnace side in the pressurizing method and in the mold in the depressurizing method. Therefore, when the amount of immersion in the gate section is increased, the airtight space is compressed, and the pressure increases. The liquid level may be detected by detecting this pressure rise. In that case, the contact portion with the molten metal only needs to be the gate, so that there is durability. FIG. 10 shows a decompression type,
FIG. 12 shows the pressure in each closed space when applied to the pressurized type. The actual pressure rise is small and is shown schematically.
In the case of the pressurized type, since the mold receiver 7 enters, the pressure rise is larger than in the case of the depressurized type. FIG. 13 shows a block diagram of liquid level detection based on an increase in pressure in an airtight space. The pressure of the furnace or the mold and the atmospheric pressure are led to the differential pressure relay 20, and when the differential pressure becomes larger than a predetermined value and the differential pressure relay 20 is turned on, it is considered that the liquid level has reached a predetermined level, A signal from the relay 20 is sent to the control panel 21 of the casting apparatus to generate a descent stop signal and a pressurization / decompression start signal. The influence of atmospheric pressure fluctuation was avoided by measuring the pressure difference from the atmosphere.

[0020]

According to the first aspect of the present invention, there is provided a pressure-type differential pressure casting method.
According to the pressure-reducing differential pressure casting method and the pressure-type differential pressure casting apparatus of claim 3, the pressure reduction and the pressure can be freely selected according to the type of the product, and the most suitable casting method is provided for each. After casting
Separating the mold and the sprue facilitates die-cutting and sprue cleaning, especially for iron-based high melting point materials. According to the device of the fourth aspect, the gate section forms a solidified film at an early stage on the contact surface even with a high melting point molten metal such as an iron-based material, so that direct contact with the molten metal is prevented, and at the same time, on the side of the gate section side. The temperature of the contact portion is maintained at a low temperature equal to or lower than the melting point of the material of the sprue portion, thereby preventing thermal damage and erosion due to the molten metal. Further, since the contact portion has an integral structure, mechanical damage is also prevented. As a result, an iron-based durable gate section, which was not previously available, has become possible. In addition, the gate section functions as an element of an airtight space required for differential pressure casting, and the occurrence of defects due to pressure leakage and the like is prevented. According to the pressure-type differential pressure casting apparatus of claim 3, it is applicable to general molds other than the gate section, and enables casting of cast steel or the like with a low quality of casting that has been proven in aluminum and the like. In addition, the intrusion of the sprue into the crucible by the sprue receiver enabled the use of an iron-based optimal crucible-type induction furnace, and a compact device having only the furnace in an airtight structure became possible. In addition, a small amount of dissolution can be maintained, and an apparatus suitable for production can be provided. Further, the path of the molten metal is short, and the heat loss can be minimized, so that the castability is improved. According to the device of the fifth aspect, since the liquid level is detected by the pressure increase in the closed space, stable and durable detection is possible as compared with the case where the sensor is brought into contact with the molten metal.

[Brief description of the drawings]

FIG. 1 is a sectional view of a part of an apparatus for performing a reduced pressure differential pressure casting method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the apparatus of FIG. 1 in a state where a gate section is immersed in a molten metal.

FIG. 3 is a sectional view of the apparatus of FIG. 1 in a state in which a cavity is filled with a molten metal.

FIG. 4 is a cross-sectional view showing a state in which about 40% of a molten metal is solidified in a cavity in the apparatus of FIG.

FIG. 5 is a cross-sectional view of the apparatus of FIG. 1, in which only the mold is raised after solidification of the molten metal.

FIG. 6 is a cross-sectional view of the apparatus of FIG. 1, in which an upper mold and a lower mold of a mold are separated after solidification of a molten metal, and residual solidified metal is removed from a sprue.

7 is a cross-sectional view of the apparatus of FIG. 1 in a state where a cast product is removed from a mold.

FIG. 8 is a plan view in the vicinity of a gate section in another embodiment.

FIG. 9 is a sectional view taken along line AA of FIG. 8;

FIG. 10 is a graph showing a change in pressure in a space in a mold in a decompression method.

FIG. 11 is a cross-sectional view of an apparatus for performing a pressure differential pressure casting method according to an embodiment of the present invention.

FIG. 12 is a graph showing a change in pressure in a closed space in a pressure furnace.

FIG. 13 is a block diagram illustrating a process of detecting a liquid level by detecting a pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gate part 1-1 Gate 1-2 Opening 1-3 Space 3 Mold 3-3 Cavity 3-61 Depressurization hole 4 Molten metal (high melting point material) 6 Remaining molten metal removing device 6-1 Drain pin 7 Mold receiving 8 Airtight lid 9 Airtight container 9-2 Pressurized gas introduction hole 20 Differential pressure relay

Claims (5)

[Claims] 1. A mold body and a sprue portion are aligned at a molten metal passage portion, a sprue portion is inserted into an opening on the molten metal of the hermetic furnace body, the spout portion is protruded into the inside of the furnace body, and the opening is formed around an outer periphery of the sprue portion. The hermetically abuts the periphery of the portion, the gate and the molten metal of the high melting point material are relatively moved, and the gate is immersed in the molten metal to a predetermined depth, and the molten metal is pressed by pressurizing the airtight furnace. Filling the cavity in the mold body, the mold body is separated from the sprue when the molten metal in the sprue and the joint part of the mold body has a solid phase ratio of about 40% or more, and is moved to the mold opening step outside the furnace. Removed from the airtight furnace body, remove the solidified molten metal of the sprue from the joint side of the mold body outside the furnace by pushing it out to the immersion end side of the molten metal, return the sprue to the furnace, and then set the mold body to perform the next casting A pressure differential casting method comprising the steps of: 2. A mold body and a sprue portion are aligned by a molten metal passage, and the periphery of the mold body is air-tightly covered with an outer casing except for the spout opening, and the sprue is immersed in the molten metal to a predetermined depth. The molten metal is filled in the cavity in the mold body, and when the molten metal at the junction of the gate and the mold body reaches a solid phase ratio of about 40% or more, the mold body is separated from the gate and the mold body is removed. Is moved to the mold opening process outside the furnace, the gate is removed from the furnace and moved out of the furnace, and the solidified molten metal in the gate is extruded from the joining surface side of the mold body to the molten metal immersion side, thereby removing the gate. Is returned to the furnace, and then the mold body is set on the sluice portion to prepare for the next casting. 3. An airtight molten metal holding container having a heating element therein, an airtight lid thereof, and an airtight elastic member such as a bellows or a sliding seal portion on the airtight lid, the outer diameter of which is smaller than that of the molten metal container. A mold receiver having an opening having a sealing surface on the periphery at the bottom surface, a liquid level detection sensor for the molten metal constituted by electrodes or optical means connected to the mold receiver, and the mold receiver comprising a cylinder or the like. Up and down driving means,
A pressurized differential pressure comprising: a control panel of vertical drive means connected to the liquid level detection means, an airtight furnace pressure control device connected to the liquid level detection sensor, and a means for attaching and detaching a mold to and from the mold receiver. Casting equipment. 4. The sprue portion has one or a plurality of through-holes, and the upper side of the through-hole can be connected to the cavity of the mold body, and has a cross-sectional shape in which the internal vertical cross-sectional shape can be drawn downward without interference. None, furthermore, at least the outer shape of the molten metal immersion portion is reduced as it goes downward, and the outer vertical cross-sectional shape is formed to be drawn downward without interference, and at least the molten metal contact portion has a cavity in which a cooling medium can flow therethrough. It has a connection port between the outside and the cavity, has a seal portion surrounding the opening on the upper surface, or has an overhang portion having a seal portion with a larger outer shape than the melt immersion portion on the lower surface, and is of the same type as the molten metal, or has a low melting point. The pressurized differential pressure casting apparatus according to claim 3, wherein the apparatus is made of a hermetic high heat conductive material such as a metal member, a ceramic member having the same thermal conductivity as metal, or a graphite member. 5. The liquid level detecting sensor comprises a detector for detecting that the gate is immersed in the molten metal when a pressure difference between a pressure in an airtight portion of the furnace and the atmosphere is equal to or higher than a predetermined value. The pressure differential pressure casting apparatus according to claim 3.