Patent Application
20250178079
The present application claims the benefit of Korean Patent Application No. 10-2023-0170433 filed in the Korean Intellectual Property Office on Nov. 30, 2023, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a high-quality casting device and method for producing a thick aluminum part, and more specifically to a high-quality casting device and method for producing a thick aluminum part that is capable of filling a molten metal into a cavity of a mold by means of tilting gravity of the molten metal and performing high-pressure squeeze pressurization against the molten metal, thereby controlling the occurrence of shrinkage defects in a thick portion of a casting.
Generally, gravity die casting is a method for pouring a molten metal into a mold under only the force of gravity, without the use of pressurization against the molten metal.
The gravity die casting enables a complex shape with an under-cut or core to be formed, thereby increasing a degree of freedom in shape, and further, the gravity die casting has more simple equipment and lower automation investment cost than low-pressure die casting or high-pressure die casting. As the molten metal is filled into the cavity of the mold under the force of gravity upon the supply of the molten metal, however, a degree of molten metal filled is relatively low, thereby having a limitation in casting a thin-walled product.
To avoid shrinkage defects from occurring on the final solidification area of a casting, further, a plurality of risers are located according to the shape of a product and serve to fill up the molten metal with shrinkage, thereby disadvantageously causing a low product collection rate, producing the product with coarse tissues due to a low solidification speed, making the mechanical properties of the product become relatively deteriorated, and having low productivity.
As one of conventional technologies that solves such disadvantages of the gravity die casting, there is disclosed Korean Patent No. 10-1794812 (entitled gravity die casting), and the above-mentioned conventional gravity die casting in which a molten metal is poured into a mold consisting of a lower mold in which a cavity is formed and an upper mold in which a riser is formed, the cavity and the riser communicating to each other so that the molten metal poured into the riser pressurizes the molten metal poured into the cavity, the gravity die casting including the steps of: pouring the molten metal into the mold; and covering a top of the upper mold with a chamber cap to form a closed space portion on the top of the upper mold, wherein the upper mold has an incised hole adapted to allow the molten metal poured thereinto to be exposed to the air existing in the chamber cap, and a top of the chamber cap is connected to a robot arm, while the periphery of the top of the chamber cap is being bent downward.
According to the above-mentioned conventional gravity die casting, the riser is simply covered with the chamber cap to prevent the heat emission thereof, so that the effect of the riser is somewhat improved through the latent heat generated from the interior of a chamber and the convection of heat energy, but a fundamental pressurizing force is too weak to freely apply the above-mentioned conventional gravity die casting to various products.
As another conventional technology, there is disclosed Korean Patent No. 10-1647891 (entitled gravity die casting), and the above-mentioned conventional gravity die casting includes the steps of: pouring a molten metal into a body of a mold; spraying a gas into the body to increase a pressure in the body; solidifying the molten metal and extracting a solidified casting from the mold. Further, the above-mentioned conventional gravity die casting includes the step of closing an entrance of the body of the mold between the step of pouring the molten metal and the step of spraying the gas into the body.
According to the above-mentioned conventional gravity die casting, after the molten metal has been filled into a cavity of the mold under the force of gravity, the entrance of the mold is closed, and after that, a low-pressure gas is sprayed into the mold, thereby pressurizing the molten metal solidified. In this case, however, a distance of a pressurizing force applied to the casting is very limited, a pressurizing effect against the casting is very low, and an additional closing device is needed to operate during a casting process. Therefore, the conventional gravity die casting has a limitation in the application to a mass production line where continuous works are required.
Accordingly, the present disclosure has been made in view of the above-mentioned problems occurring in the related art, and it is an object of the present disclosure to provide a high-quality casting device and method for producing a thick aluminum part that is capable of closing a sprue, after a molten metal has been filled into a cavity under the force of gravity, and performing squeeze pressurization against the periphery of a thick portion of a product by means of a high-pressure squeeze pressurizer, so that through the squeeze pressurization, an amount of molten metal decreasing due to shrinkage during solidification can be completely filled up, without any risers necessarily used in the existing gravity die casting, thereby optimizing a product collection rate and improving mechanical properties of the product through the refinement of solidified tissues.
To accomplish the above-mentioned objects, according to a first aspect of the present disclosure, there is provided a high-quality casting device for producing a thick aluminum part, including: a mold having a movable mold and a fixed mold coming into close contact with each other to form a cavity; a platen having a movable platen on which the movable mold is mounted and a fixed platen on which the fixed mold is mounted; an upper tie bar and a lower tie bar connected to upper and lower portions of the platen; a high-pressure squeeze platen connected to the upper tie bar and the lower tie bar in such a way as to be spaced apart from the fixed platen by a given distance; a squeeze pressurizer located on the high-pressure squeeze platen to pressurize a molten metal filled into the cavity; a sprue adapted to pour the molten metal into the cavity of the mold; a pouring ladle attached to the mold to pour the molten metal into the sprue; and a casting extractor located on one side of the mold to extract the casting solidified inside the cavity.
According to the present disclosure, desirably, the squeeze pressurizer may include: a squeeze pressurization cylinder fitted to the high-pressure squeeze platen to generate a pressurizing force; a squeeze plunger moving forwards and backwards with the pressurizing force received from the squeeze pressurization cylinder to pressurize the molten metal filled into the cavity; and a squeeze plunger bush fitted to the fixed platen to guide the squeeze plunger.
According to the present disclosure, desirably, the casting device may further include a sprue closer located on the fixed mold or the movable mold to open and close the sprue.
According to the present disclosure, desirably, the sprue closer may include: a sprue closing cylinder located on the fixed mold or the movable mold to generate a pressurizing force; and a sprue closing pin moving forwards and backwards with the pressurizing force received from the sprue closing cylinder to open and close the sprue.
To accomplish the above-mentioned objects, according to a second aspect of the present disclosure, there is provided a high-quality casting method for producing a thick aluminum part, the casting method including the steps of: pouring a molten metal in a pouring ladle connected to a mold; filling the molten metal poured into the pouring ladle into a cavity of the mold preheated; closing the entrance of a sprue through a sprue closer after the filling of the molten metal into the cavity of the mold has been completed; if given set time passes after the entrance of the sprue has been closed, performing squeeze pressurization against the molten metal by means of a squeeze pressurizer; cooling, solidifying, and molding the molten metal by means of a cooling channel inside the mold; if given set molding time passes, opening the mold and extracting a casting from the mold; and spraying a release agent into the surface of the mold after the casting has been extracted.
According to the present disclosure, desirably, the step of pouring the molten metal into the cavity may be performed with either a tilting method for filling the molten metal using the pouring ladle attached to the mold or a method for directly pouring the molten metal into the cavity of the mold.
According to the present disclosure, desirably, in the step of performing squeeze pressurization, an amount of squeeze pressurization may be greater than or equal to 6% of a volume of the casting.
The above and other objects, features and advantages of the present disclosure will be apparent from the following detailed description of the preferred embodiments of the disclosure in conjunction with the accompanying drawings, in which:
Hereinafter, example embodiments will be described with reference to the accompanying drawings. However, it should be understood that the example embodiments covers all the modifications, equivalents, and alternatives within the idea and technical scope of the disclosure. In addition, for reference numerals, with respect to the same elements, even though they may be displayed in different drawings, such elements use same reference numerals as much as possible.
The term ‘including’ and/or ‘having’, as used herein are intended to refer to the above features (e.g., numbers, functions, operations, or components), and it is to be understood that the terms are not intended to preclude the presence of one or more features.
As used in the present disclosure (particularly in the appended claims), the singular forms and “at least one of A or B, “at least one of A or/and B”, or “at least one or more of A or/and B” are intended to include the plural forms as well, unless the context clearly indicates otherwise. For example, a list of “A or B”, “at least one of A and B”, or “at least one of A or B” means (1) one A, (2) one B, and one A and one B, unless the context clearly indicates otherwise.
Terms used in this application are used to only describe specific exemplary embodiments and are not intended to restrict the present invention. An expression referencing a singular value additionally refers to a corresponding expression of the plural number, unless explicitly limited otherwise by the context. All terms used herein, including technical or scientific terms, unless otherwise defined, have the same meanings which are typically understood by those having ordinary skill in the art. The terms, such as ones defined in common dictionaries, should be interpreted as having the same meanings as terms in the context of pertinent technology, and should not be interpreted as having ideal or excessively formal meanings unless clearly defined in the specification.
Before the present invention is disclosed and described, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to variously employ the present invention in virtually any appropriately detailed structure.
According to an embodiment of the present disclosure, a high-quality casting device for producing a thick aluminum part, including: a mold 10 having a movable mold 11 and a fixed mold 12 coming into close contact with each other to form a cavity 13; a platen 20 having a movable platen 21 on which the movable mold 11 is mounted and a fixed platen 22 on which the fixed mold 12 is mounted; an upper tie bar 31 and a lower tie bar 32 connected to upper and lower portions of the platen 20; a high-pressure squeeze platen 23 connected to the upper tie bar 31 and the lower tie bar 32 in such a way as to be spaced apart from the fixed platen 22 by a given distance; a squeeze pressurizer located on the high-pressure squeeze platen 23 to pressurize a molten metal filled into the cavity 13; a sprue 14 adapted to pour the molten metal into the cavity 13 of the mold 10; a pouring ladle 50 attached to the mold 10 to pour the molten metal into the sprue 14; and a casting extractor 60 located on one side of the mold 10 to extract the casting solidified inside the cavity 13.
According to the embodiment of the present disclosure, briefly, the high-quality casting device includes the movable mold 11, the fixed mold 12, the movable platen 21, the fixed platen 22, the upper tie bar 31, the lower tie bar 32, the high-pressure squeeze platen 23, the squeeze pressurizer, the sprue 14, the pouring ladle 50, and the casting extractor 60.
As shown in
The upper tie bar 31 and the lower tie bar 32 are located to guide the upper and lower portions of the platen 20, and the movable platen 21 is supported against the upper tie bar 31 and the lower tie bar 32 so that it receives the pressurizing force of the opening/closing cylinder 80 and thus moves forwards and backwards.
The high-pressure squeeze platen 23 is supported against the upper tie bar 31 and the lower tie bar 32 in such a way as to be spaced apart from the fixed platen 22 by a given distance, and further, a squeeze pressurization cylinder 40 of the squeeze pressurizer as will be discussed later is fitted to the high-pressure squeeze platen 23.
The sprue 14 is a path through which the molten metal is poured into the cavity 13 formed in the mold 10.
Methods for pouring the molten metal into the cavity 13 through the sprue 14 include a tilting method wherein the molten metal is poured into the pouring ladle 50 attached to the mold 10 and next, the casting device tilts to fill the molten metal into the cavity 13 and a method wherein the molten metal is poured directly into the sprue 14 and thus filled into the cavity 13 of the mold 10.
If cooling for the mold 10 is performed after the molten metal has been filled into the cavity 13, the molten metal is solidified so that a casting is extracted from the mold 10, and so as to remove the solidified casting from the mold 10, in this case, the casting extractor 60 is located on one side of the mold 10. After the mold 10 has opened, if an extraction cylinder located on the casting extractor 60 applies a pressurizing force to extrusion pins brought into close contact with the casting, the extrusion pins push the casting so that the casting is extracted from the mold 10.
Further, the squeeze pressurizer includes: the squeeze pressurization cylinder 40 fitted to the high-pressure squeeze platen 23 to generate a pressurizing force; a squeeze plunger 41 moving forwards and backwards with the pressurizing force received from the squeeze pressurization cylinder 40 to pressurize the molten metal filled into the cavity 13; and a squeeze plunger bush 42 fitted to the fixed platen 22 to guide the squeeze plunger 41.
That is, the squeeze pressurizer includes the squeeze pressurization cylinder 40, the squeeze plunger 41, and the squeeze plunger bush 42.
The squeeze pressurization cylinder 40 is fitted to the high-pressure squeeze platen 23 to generate the pressurizing force so that the squeeze plunger 41 moves forwards and backwards.
The squeeze plunger 41 has one side connected to the squeeze pressurization cylinder 40 and the other side inserted into the fixed mold 12. If the squeeze plunger 41 moves forwards and backwards, the other side of the squeeze plunger 41 enters the cavity 13 of the mold 10, so that if the molten metal is filled into the cavity 13, the squeeze plunger 41 pressurizes the molten metal.
To allow the other side of the squeeze plunger 41 to be inserted into the fixed mold 12, while one side of the squeeze plunger 41 is being connected to the squeeze pressurization cylinder 40, the squeeze plunger 41 passes through the fixed platen 22, and in this case, the squeeze plunger bush 42 is located on the fixed platen 22 to protect and guide the squeeze plunger 41.
According to the embodiment of the present disclosure, the high-quality casting device further includes a sprue closer located on the fixed mold 12 or the movable mold 11 to open and close the sprue 14.
In this case, the sprue closer includes: a sprue closing cylinder 70 located on the fixed mold 12 or the movable mold 11 to generate a pressurizing force; and a sprue closing pin 71 moving forwards and backwards with the pressurizing force received from the sprue closing cylinder 70 to open and close the sprue 14.
Desirably, a hydraulic cylinder is used as the sprue closing cylinder 70, and if the pouring of the molten metal into the cavity 13 of the mold 10 is completed, a sprue closing circuit signal is transmitted to the sprue closer, and the sprue closing cylinder 70 receives the sprue closing circuit signal, moves the sprue closing pin 71 forwards, and thus closes the sprue 14, so that upon the squeeze pressurization, the sprue 14 is closed to prevent the molten metal from leaking therefrom.
Further, a high-quality casting method for producing a thick aluminum part according to the present disclosure includes the steps of: pouring the molten metal into the pouring ladle 50 connected to the mold 10; filling the molten metal poured into the pouring ladle 50 into the cavity 13 of the mold 10 preheated; closing the entrance of the sprue 14 through the sprue closer after the filling of the molten metal into the cavity 13 of the mold 10 has been completed; if given set time passes after the entrance of the sprue 14 has been closed, performing squeeze pressurization against the molten metal by means of the squeeze pressurizer; cooling, solidifying, and molding the molten metal by means of a cooling channel inside the mold 10; if given set molding time passes, opening the mold 10 and extracting a casting from the mold 10; and spraying a release agent into the surface of the mold 10 after the casting has been extracted.
In step S10, the molten metal stored in a holding furnace is primarily poured into the pouring ladle 50. In this case, the molten metal may be supplied through a single pouring ladle 50 or a plurality of pouring ladles 50, and the pouring ladle 50 is desirably pre-heated and thus holds the temperature of the molten metal according to the shape of the surface thereof. The supply of the molten metal to the pouring ladle 50 is performed by means of automatic pouring using a robot.
In step S20, the molten metal poured by a fixed quantity is filled into the cavity 13 of the preheated mold 10.
As the method for filling the molten metal into the cavity 13, as mentioned above, the tilting method or direct pouring method may be adopted, and if the tilting method is used, it is desirable that a filling speed and a filling time of the molten metal be precisely controlled through a servomotor and a worm gear.
In step S30, the entrance of the sprue 14 is closed through the sprue closer after the filling of the molten metal into the cavity 13 of the mold 10 has been completed. As a method for closing the sprue 14, it is desirable to close the sprue 14 through the sprue closer located on any one of the fixed mold 12 and the movable mold 11.
As the sprue 14 is closed, the cavity 13 of the mold 10 is sealed, and if the squeeze pressurization is performed through the squeeze pressurizer, in this case, the molten metal is prevented from gushing out through the sprue 14.
In step S40, if the sprue 14 is closed through the sprue closer, the sprue closing circuit signal is transmitted to a controller (not shown). If the controller receives the sprue closing circuit signal, it allows the squeeze plunger 41 of the squeeze pressurizer to move forwards.
In step S50, the squeeze pressurization is performed through the squeeze pressurizer. If given set time passes after the sprue 14 has been closed, the squeeze plunger 41 moves forwards to pressurize the molten metal in the cavity 14. If the squeeze plunger 41 pressurizes the molten metal in the cavity 14 of the mold 10, a pressurizing force is applied to the molten metal so that the molten metal is prevented from having shrinkage defects, increases in a solidification speed thereof, and has refine tissues to remarkably improve mechanical properties thereof. In this case, it is desirable that a section of a pressurization volume be set and the cooling of the squeeze plunger 41 be controlled in consideration of the solidification of the molten metal.
Further, if the mold 10 has a plurality of cavities 13, the number of squeeze plungers 41 corresponds to the number of cavities 13 so that the squeeze plungers 41 perform the squeeze pressurization together. If the plurality of squeeze plungers 41 are adopted, they are mounted on one squeeze pressurization cylinder 40, so that upon the forward and backward movements of the squeeze pressurization cylinder 40, the plurality of squeeze plungers 41 perform the squeeze pressurization against the molten metal filled into the plurality of cavities 13 at a time.
If a clamping force between the fixed mold 12 and the movable mold 11 does not increase in proportion to the pressurizing force generated upon the squeeze pressurization, further, the fixed mold 12 and the movable mold 11 are separated from each other, thereby causing a defection. In consideration of a safety factor, therefore, it is desirable that the clamping force between the fixed mold 12 and the movable mold 11 generated through the opening/closing cylinder 80 be 1.5 times higher than the squeeze pressurization.
In the case of all metals including an aluminum alloy, shrinkage occurs in a process where the molten metal is solidified after the molten metal has been filled into the cavity 13 of the mold 10, and therefore, it is natural that shrinkage cavities (shrinkage defects) are necessarily generated on the final solidification area due to the molten metal not filled into dendrites. In the case of the aluminum alloy, volume shrinkage upon high-pressure die casting is in the range between 3 and 6%. To solve such a problem, various casting methods and techniques are required, and unless the supply of the molten metal for the shrinkage is performed continuously, the shrinkage cavities are necessarily generated.
As shown in
According to the embodiment of the present disclosure, after the molten metal has been filled into the central portion of the thick portion, the molten metal for the shrinkage is sufficiently supplied through high-pressure squeeze pressurization against the filled molten metal, thereby controlling the occurrence of shrinkage defects, increasing the solidification speed of the casting through the pressurization, and remarkably improving the mechanical properties of the casting through the refinement of solidified tissues. In this case, it is very important to design an amount of squeeze pressurization, and desirably, an amount of squeeze pressurization as a squeeze volume is greater than or equal to 6% of a volume of the casting, thereby expecting the effect of pressurization.
In step S60, cooling, solidification, and molding of the molten metal are performed by means of a cooling channel inside the mold 10 during a given set period of time, and in step S70, after the given set period of time, the mold 10 is open to extract the casting from the mold 10. Next, a release agent is sprayed into the surface of the mold 10.
The release agent makes a barrier between the molten metal and the mold 10 to prevent the molten metal solidified inside the cavity 13 from being coupled to the surface of the mold 10, thereby protecting the mold 10 from damages and allowing the mold 10 and the casting to be easily separated from each other.
In step S80, the squeeze plunger 41 moves backwards (is returned to its original position) and the spraying of the release agent is then completed.
Further, the step of pouring the molten metal into the cavity 13 is performed with either a tilting method for filling the molten metal using the pouring ladle 50 attached to the mold 10 or a method for directly pouring the molten metal into the cavity 13 of the mold 10.
Moreover, in the step of performing squeeze pressurization, an amount of squeeze pressurization is greater than or equal to 6% of a volume of the casting.
Through the above casting method, therefore, the occurrence of internal defects is more controllable than that in the existing gravity die casting or low-pressure die casting, and further, grain refinement of the casting is achieved to improve the mechanical properties of the casting. Besides, cycle time is decreased by more than 30% of cycle time of the existing gravity die casting, thereby improving the competitivity in a manufacturing cost.
As described above, the high-quality casting device and method for a thick aluminum part according to the present disclosure is configured to perform high-pressure squeeze pressurization and mold cooling, so that the occurrence of internal shrinkage defects is more controllable than that in the existing gravity die casting or low-pressure die casting, and further, grain refinement of the casting is achieved to improve the mechanical properties of the casting.
Further, the high-quality casting device and method for a thick aluminum part according to the present disclosure is configured to allow cycle time to be decreased by more than 30% of cycle time of the existing gravity die casting, thereby lowering a manufacturing cost thereof, and configured to have no risers for compensating for the casting shrinkage in the existing techniques, thereby achieving more than 90% of product collection rate, minimizing the amount of scraps generated to greatly reduce an energy production cost and an amount of carbon dioxide which are generated upon re-melting.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any specific arrangement of software, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present disclosure. Therefore, it is manifestly intended that this disclosure be limited only by the claims and the equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0170433 | Nov 2023 | KR | national |
