Patent Application
20250187067
This application claims priority to and the benefit of Korean Patent Application Nos. 10-2023-0175598, filed on Dec. 6, 2023, and 10-2024-0168264, filed on Nov. 22, 2024, the entire contents of each of which are incorporated herein by reference.
The present disclosure relates to a pressure casting device and a method for manufacturing a casting using the same, and more particularly, to a pressure casting device capable of suppressing the occurrence of casting defects, and a method for manufacturing a casting using the same.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In a process of casting a lightweight metal such as aluminum, magnesium, or zinc, a shrinkage defect caused by a decrease in volume of molten metal during a process of solidifying the liquid metal and a bubble defect caused by a decrease in solubility of hydrogen gas may occur.
In conventional casting technologies, in order to prevent these defects, pressure is applied to a gating, which is a local surface of a molten metal, to compensate for solidification shrinkage and suppress bubble defects. These conventional casting technologies include gravity casting, low-pressure casting, high-pressure casting, and differential pressure casting methods depending on how to apply pressure.
However, in these conventional casting technologies, in order to suppress shrinkage and bubble generation, pressure is directly applied to a local molten metal surface of a gating portion where the molten metal is injected, which makes it difficult to fundamentally prevent the occurrence of defects in a portion solidified during the filling of the molten metal or in a region away from the gating, although good quality can be obtained around the gating where pressure loss is small. In addition, if the local pressing force exerted on the molten metal is excessive, the molten metal may penetrate into a mold gap, a core, and mold particles, causing burrs and sticking defects.
In the case of the differential pressure casting method, the occurrence of burrs caused by the pressing force on the molten metal can be suppressed to some extent by pressurizing the inside of the chamber while filling and solidifying the molten metal, but it is not possible to fundamentally resolve the problems of pressure imbalance and bubble generation caused by locally pressurizing the molten metal, as well as burrs and sticking defects.
The present disclosure provides a pressure casting device and a method for manufacturing a casting using the same, which are capable of fundamentally resolving shrinkage and bubble generation in an entire casting while preventing burrs and sticking defects by filling a molten metal into an outer mold and solidifying the molten metal under casting atmospheric pressurization in manufacturing the casting.
An embodiment of the present invention provides a pressure casting device. The pressure casting device includes: a chamber having an opening portion formed on a first side and sealed on a second side; an outer mold including: a filling space into which a molten metal is filled, and a casting space connected to the filling space such that the molten metal is supplied from the filling space into the casting space and filled in a shape of a casting; and a self-shielding mold table configured to fix the outer mold. The self-shielding mold table is insertable into and drawable from the chamber and includes first and second sealing portions configured to seal the opening portion of the chamber and an inner side portion facing the opening portion of the chamber, respectively, and an outer mold support portion contacting the outer mold to support the outer mold. The pressure casting device includes a pneumatic pressure injector provided at one side portion of the chamber to supply pneumatic pressure into the chamber; and a tilting device configured to rotate the chamber.
The outer mold may be made of a porous material, and manufactured from a sand mold or a powder-sintered metal mold.
A core structure for forming a hollow in the casting may be provided in the casting space.
An edge end of each of the first and second sealing portions may be in contact with an inner surface of the chamber and sealed by a sealing member.
The first and second sealing portions have different areas and are configured to cause a pressing force to act from the opening portion to the inner side portion. In an embodiment, the first sealing portion may be formed to have a smaller area than the second sealing portion.
The pneumatic pressure injector may inject compressed air or nitrogen into the chamber at a pressure in a range of 1 kg/cm2 to 100 kg/cm2.
When the pneumatic pressure injection device injects the compressed air or nitrogen into the chamber, a first pressure may be applied to the second sealing portion. The first pressure is higher than a second pressure applied to the first sealing portion, so that the self-shielding mold table is fixed not to be removed from the chamber.
The tilting device may rotate the chamber at an angle in a range of 90° to 180°.
When the tilting device rotates, the molten metal filled in the filling space flows into the casting space.
The pressure casting device may further include a pressure reducer configured to reduce and exhaust the pressure in the chamber after the molten metal in the casting space is completely solidified.
Another embodiment of the present invention provides a method for manufacturing a casting using the pressure casting device. The method includes: injecting a molten metal into the filling space of the outer mold; inserting the outer mold into the chamber and sealing the chamber, and injecting pneumatic pressure into the chamber to pressurize the chamber; rotating the chamber using the tilting device to inject the molten metal filled in the filling space into the casting space; solidifying the molten metal while maintaining the pressurized state in the chamber to form a casting; and reducing and exhausting the pressure in the chamber after the formation of the casting is completed, drawing the outer mold from the chamber, and then demolding the casting.
In the injecting of the molten metal into the filling space of the outer mold, the molten metal may be injected into the filling space using a molten metal injector in a state where the outer mold is drawn from the chamber.
In the demolding of the casting, the outer mold may be separated and the casting may be demolded in a state where the outer mold is drawn from the chamber.
Another exemplary embodiment of the present invention provides a pressure casting device including: a chamber having a bottom portion and a cover portion sealed by being combined with the bottom portion; an outer mold provided inside the chamber, and having a filling space into which a molten metal is filled, and a casting space connected to the filling space such that the molten metal is supplied from the filling space into the casting space and filled in a shape of a casting; and a pneumatic pressure injector provided at one side portion of the chamber to supply pneumatic pressure into the chamber.
The outer mold may include: a metal mold supported by the bottom portion and forming a part of the casting space; and a sand mold combined with an upper portion of the metal mold and forming the other part of the casting space and the filling space.
The molten metal may be supplied from the filling space into the casting space by gravity.
The sand mold may be made of a porous material.
A core structure for forming a hollow in the casting may be provided in the casting space.
An edge end of the cover portion may be in contact with an upper surface of the bottom portion and sealed by a sealing member.
The pneumatic pressure injector may inject compressed air or nitrogen into the chamber at a pressure in a range of 1 kg/cm2 to 100 kg/cm2.
According to the present disclosure, by injecting a molten metal into the outer mold and solidifying the molten metal under casting atmospheric pressurization, the pressing force is applied uniformly to the entire surface of the molten metal in a direction toward the molten metal in the outer mold, thereby fundamentally resolving burrs and sticking defects.
In addition, according to the present disclosure, it is possible to ensure a casting with an internal density (porosity) equivalent to that of a forging, thereby improving mechanical properties when compared to products to which the conventional casting technologies are applied.
In addition, high-pressure and high-strength parts for pressure resistance that were previously manufactured using conventional forging methods can be manufactured and replaced with current casting materials.
In addition, according to the present disclosure, it is possible to cast a forging material (such as 6000 series aluminum), which cannot be cast due to a shrinkage defect issue if the conventional technology is used, making it possible to manufacture castings from high-heat dissipation materials and high-ductility materials.
In addition, according to the present disclosure, when applied to high-strength/high-heat dissipation/light-weight and aluminum/magnesium/zinc material-requiring fields, it is possible to reduce the manufacturing cost while enhancing the quality as compared to conventional technology.
In addition, when applying the self-shielding chamber structure according to the present disclosure, the equipment structure can be simplified, stability can be ensured, and the processing time can be shortened.
Hereinafter, embodiments of the present disclosure are described in detail with reference to the accompanying drawings, so that they can be easily carried out by those having ordinary skill in the art to which the present disclosure pertains. The present disclosure may be implemented in various different forms and is not limited to the embodiments described herein.
In addition, in describing various embodiments, the same configuration is representatively described in one embodiment using the same reference numerals for the same components, and only configurations different from those in the one embodiment are described in the other embodiments. It should be noted that the drawings are schematic and not drawn to scale. The relative dimensions and proportions of parts in the drawings may be exaggerated or diminished in size for the sake of clarity and convenience in the drawings, and any dimensions are merely illustrative and are not limiting. The same reference signs are used for the same structures, elements, or parts shown in two or more drawings to show similar features. When one part is referred to as being “over” or “on” another part, the one part may be directly over or on the other part, or there may be an intervening part therebetween. When a component, device, element, or the like of the present disclosure is described as having a purpose or performing an operation, function, or the like, the component, device, or element should be considered herein as being “configured to” meet that purpose or to perform that operation or function.
Embodiments of the present disclosure are represented by one specific exemplary embodiment of the present disclosure. As a result, various modifications of the embodiments are expected. Therefore, the embodiments are not limited to the illustrated specific forms and the scope of the present disclosure should include modifications of the forms caused, for example, in the manufacturing process.
Hereinafter, a pressure casting device according to an embodiment of the present disclosure is described in detail with reference to the accompanying drawings.
Referring to
The chamber 10 may be a pneumatic chamber having an opening portion 12 on one side (e.g., a first side) and sealed on the other side (e.g., a second side), facing the one side (i.e., the first side). The opening portion 12 may be sealed by a sealing portion 34 during a pressure casting process, thereby sealing the entire chamber 10.
The outer mold 20 may be a porous mold capable of transmitting an atmospheric pressing force to a surface of a molten metal M within the cavity. The porous mold may be manufactured from a sand mold or a powder-sintered metal mold.
The outer mold 20 may have a filling space (e.g., a casting plan) 22 and a casting space 24. The molten metal M may be filled into the filling space 22 from the outside in a state where the outer mold 20 is exposed to the outside of the chamber 10.
The casting space 24 is connected to the filling space 22, and the molten metal M may be supplied from the filling space 22 into the casting space 24 so that the casting space 24 is filled in a shape of a casting. In other words, the molten metal M is injected into the filling space 22 in a state where the outer mold 20 is exposed to the outside through the opening portion 12 of the chamber 10, and the molten metal M flows from the filling space 22 into the casting space 24 in a state where the outer mold 20 is inserted into the chamber 10 and the entire chamber 10 is sealed. At this time, the chamber 10 may be rotated so that the molten metal M can naturally flow by gravity from an outlet of the filling space 22 to an inlet of the casting space 24.
A core structure 26 for forming a hollow in a casting may be provided in the casting space 24. In other words, for a shape of a middle portion of the casting, the core structure 26 may be formed in various shapes, and the hollow of the casting may be formed according to the shape of the core structure 26.
The self-shielding mold table 30 fixes the outer mold 20 and is insertable into and drawable from the chamber 10. The self-shielding mold table 30 may have a first sealing portion 32 and a second sealing portion 34 to seal the opening portion 12 of the chamber 10 and an inner side portion 14 facing the opening portion 12 of the chamber 10, respectively. In addition, the self-sealing mold table 30 may have outer mold support portions 38 and 39 that contact the outer mold 20 to support the outer mold 20.
The self-shielding mold table 30 is pressed against an inner wall of the pneumatic chamber 10 by inner sealing and outer sealing to seal the pneumatic chamber 10 when pneumatic pressure is applied the chamber 10. In other words, an edge end of the first sealing portion 32 is in contact with an inner surface of the chamber 10 and is sealed by sealing members 31 and 33. Each of the sealing members 31 and 33 may be interposed between the end of the first sealing portion 32 and the inner surface in the opening portion 12 of the chamber 10, and between the outer mold support portion 38 on the bottom side and the inner surface of the chamber 10.
In addition, an edge end of the second sealing portion 34 is in contact with the inner side of the chamber 10 and is sealed by sealing members 35 and 37.
In this case, the first sealing portion 32 is formed to have a smaller area than the second sealing portion 34, so that force acts in a closing direction from the opening portion 12 to the inner side portion 14, thereby shielding the pneumatic chamber 10 with pressing force, without the need for a separate shielding mechanism.
The pneumatic pressure injection device 40 is connected to an opening formed in one surface of the chamber 10, and may pressurize a casting by injecting compressed air or nitrogen through the opening. The pneumatic pressure injection device 40 may selectively inject compressed air or nitrogen into the chamber 10 at a pressure in a range of about 1 kg/cm2 to about 100 kg/cm2 based on the weight, shape, and material of the casting.
The tilting device 50 may be a rotating device configured to form an incline in the chamber 10, allowing the molten metal M in the filling space 22 of the outer mold 20 to be injected into the casting space 24. The tilting device 50 may rotate the chamber 10 at an angle in a range of about 90° to about 180°.
Referring to
When the pressure applied to the molten metal M increases to about 6 BAR, the amount of hydrogen that can be dissolved increases as compared to that when the pressure applied to the molten metal M is about 1 BAR, which reduces the amount of bubble generation. In other words, by applying pressure to the outer mold 20 and the molten metal M, generation of bubble hydrogen is prevented in a casting, and this principle constitutes a mechanism of the present disclosure.
Referring to
As the compressed pressure on the molten metal M increases, the solubility of hydrogen in the molten metal M increases, thereby suppressing the generation of hydrogen bubbles and micro-shrinkage pores, and the pressing force acts from the outer mold 20 toward the molten metal M, thereby fundamentally blocking the occurrence of sticking burns and burrs when the molten metal M penetrates through the outer mold 20.
The tilting device 50 rotates the outer mold 20 and the chamber 10 under atmospheric pressurization to fill the casting space 24 in the outer mold 20 with the molten metal M and allow it to solidify. The rotation speed, angle, and solidification time of the tilting device 50 vary depending on the characteristics of the product.
The pressure casting device 100 according to an embodiment of the present disclosure may further include a pressure reducing and exhausting device 60 for reducing and exhausting the pressure in the chamber 10 after the solidification of the molten metal M in the casting space 24 is completed.
When the solidification of the molten metal M in the outer mold 20 is completed, the pressure inside the chamber 10 is reduced and exhausted and the product is extracted, thereby completing the casting process.
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The chamber 110 may have a bottom portion 112 and a cover portion 114 sealed by being combined with the bottom portion 112. An edge end of the cover portion 114 is in contact with an upper surface of the bottom portion 112, and a sealing member 131 may be interposed therebetween to seal the chamber 110.
The outer mold 120 is provided inside the chamber 110 and supported on the bottom portion 112 of the chamber 110. The outer mold 120 may have a filling space 122 into which the molten metal M is filled, and a casting space 124 connected to the filling space 122 such that the molten metal M is supplied from the filling space 122 into the casting space 124 and filled in a shape of a casting.
The molten metal M may be supplied from the filling space 122 to the casting space 124 by gravity.
In an embodiment, the outer mold 120 may include a metal mold 125 supported by contacting the bottom portion 112 and forming a part of the casting space 124, and a sand mold 123 combined with an upper portion of the metal mold 125 and forming the other part of the casting space 124 and the filling space 122.
The sand mold 123 may be made of a porous material, and a core structure 126 for forming a hollow in a casting may be provided in the casting space 124.
The pneumatic pressure injection device 140 may selectively inject compressed air or nitrogen into the chamber 110 at a pressure in a range of about 1 kg/cm2 to about 100 kg/cm2.
The pneumatic pressure injected into the chamber 110 is evenly applied to the filling space 122 and a part of the casting space 124 through the outer mold 120 made of a porous material, and to the molten metal M injected into the outer mold 120.
In this case, it is not possible to suppress the generation of microbubbles in the already solidified portion before pressurization and in the metal mold 125 of the outer mold 120 where the atmospheric pressing force is not applied.
When the molten metal M is solidified and the formation of the casting is completed, the pressure inside the chamber 110 is reduced and exhausted using a pressure reducing and exhausting device (e.g., a pressure reducer) (not shown), and the cover portion 114 is removed and the casting is demolded from the outer mold 120.
In this way, according to the present disclosure, by injecting a molten metal into the outer mold and solidifying the molten metal under casting atmospheric pressurization, the pressing force is applied uniformly to the entire surface of the molten metal in a direction toward the molten metal in the outer mold, thereby fundamentally resolving burrs and sticking defects.
In addition, according to the present disclosure, it is possible to provide a casting with an internal density (porosity) equivalent to that of a forging, thereby improving mechanical properties when compared to products to which the conventional casting technologies are applied.
In addition, high-pressure and high-strength parts for pressure resistance that are manufactured using conventional forging methods can be manufactured and replaced with current casting materials.
In addition, according to the present disclosure, it is possible to cast a forging material (such as 6000 series aluminum), which cannot be cast due to a shrinkage defect issue if the conventional technology is used, making it possible to manufacture castings from high-heat dissipation materials and high-ductility materials.
In addition, according to the present disclosure, when applied to high-strength/high-heat dissipation/light-weight and aluminum/magnesium/zinc material-requiring fields, it is possible to reduce the manufacturing cost while enhancing the quality as compared to conventional technology.
In addition, when applying the self-shielding chamber structure according to the present disclosure, the equipment structure can be simplified, stability can be ensured, and the processing time can be shortened.
Although the some embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above, and includes all modifications that can be easily made by those having ordinary skill in the art to which the present disclosure pertains from the embodiments of the present disclosure within the scope in which the modifications are deemed equivalent to the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0175598 | Dec 2023 | KR | national |
| 10-2024-0168264 | Nov 2024 | KR | national |
