Patent Application
20230120008
The present disclosure relates to a tilt casting mold, a tilt casting apparatus, and a tilt casting method, more particularly, to a tilt casting mold, a tilt casting apparatus, and a tilt casting method that can manufacture a molded product with a small quality difference without compensation for contraction of molten metal by forming a riser on a tilt casing mold and pressing the riser.
Tilt casting that is a kind of casting that uses a permanent (semi-permanent) mold is applied to various industrial fields.
In low-pressure casting such as tilt casting, it is required to design a mold reflecting contraction compensation in consideration of contraction in the phase change process into a solid state from a liquid state of metal when molten metal is cooled.
In Korean Utility Model Application Publication No. 20-2011-0001719, a “Ladle for gravity casting machine” that removes oxides produced on the surface of a molten material has been disclosed. The ladle includes: bar support rings disposed on both ends of the ladle at a molten material inlet provided in the mold; bars with both ends respectively fitted and supported in the bar support rings; a plurality of oxide-sticking plate support rings fitted to each bars; and an oxide-sticking plate fixed to the lower ends of the plurality of oxide-sticking plate support rings and sticking oxides produced on the surface of a molten material when the molten material flows to the molten material inlet with the ladle inclined for casting.
According to the tilt casting of the related art, the complexity of mold design is increased, a defective proportion and a quality difference in repeated production are large, and dependence on work skillfulness is high, making process automation almost impossible.
Further, it may be required to manually inject more molten material during operation of a tilting apparatus (in the process of injecting a molten material in a ladle by tilting a mold), so there are many parts to be improved such as the work time, the required manpower, and the amount of molten material to be injected.
In order to solve the problems in tilt casting of the related art described above, an objective of the present disclosure is to provide a tilt casting apparatus and a tilt casting method that can automate a process without compensation in a cavity by including a pressing apparatus that presses a riser after tilting, and a tilt casting mold that is used for the apparatus and method.
In order to solve the problems in the tilt casting of the related art, the present disclosure provides a tilt casting mold that includes a cope and a drag, in which when the cope and the drag are combined, a predetermined cavity is formed therein and a riser is formed on a side of the cavity; a pouring cup is coupled to a surface having the riser of the drag; molten material is poured in the pouring cup and then the molten metal in the pouring cup is injected into the cavity by tilting the mold assembly composed of the cope, the drag, and the pouring cup.
Further, there is provided a tilt casting apparatus that includes: the tilt casting mold described above, a tilting apparatus injecting molten metal into the cavity by tilting the tilt casting mold at a predetermined speed, and a pressing apparatus pressing the riser and including: a riser cover formed to accommodate the outer surface of the riser of the tilt casting mold and forming a predetermined sealed space including the riser by being fixed to the tilt casting mold; and a piston accommodated inside the riser cover and pressing the riser in the sealed space formed by the riser cover fixed to the tilt casting mold, in which the pouring cup is separated after molten metal is injected into the cavity by operating the tilting apparatus, the riser cover is fixed to the tilt casting mold to accommodate the riser, and then the riser is pressed by the piston.
The pressing apparatus may further include a hydraulic apparatus that presses the riser cover and the piston such that the pressure applied to the tilt casting mold by the riser cover is larger than the pressure applied to the molten metal by the piston.
The hydraulic pressure may be connected to the riser cover and the piston through a single hydraulic circuit while the area of a cross-section perpendicular to the pressing direction of the riser cover is larger than that of the piston.
An electromagnet may be disposed on a side of the riser cover such that the pressing apparatus brings the riser cover and the tilt casting mold in close contact with each other when the riser is pressed by the piston.
The riser cover and the tilt casting mold may have fasteners corresponding to each other such that the pressing apparatus couples and fixes the riser cover and the tilt casting mold when the riser is pressed by the piston.
The pressing apparatus may be configured to start pressing the cavity under the condition of
in which (1) the cross-sectional area of the piston is A, (2) the internal cross-sectional area of the riser cover is B, (3) the insertion depth of the piston in the riser is L1, (4) the internal depth of the riser cover is L2, and (5) the depth of the riser is L3.
Further, the present disclosure provides a tilt casting method that uses the tilt casting apparatus and includes: a pouring cup coupling step of fixing a pouring cup to the tilt casting mold; a first molten metal injection step of injecting molten metal into the pouring cup after the pouring cup coupling step; a second molten metal injection step of injecting the molten metal in the pouring cup into the cavity using gravity by tilting the tilt casting mold after the first molten metal injection step; a pouring cup separation step of separating the pouring cup from the tilt casting mold after the second molten metal injection step; pressing preparation step of bringing the riser cover in close contact with the tilt casting mold to accommodate the riser after the pouring cup separation step; a pressing step of pressing the molten metal in the riser by pushing the piston after the pressing preparation step; a cooling step of cooling the molten metal during the pressing step; a pressure removing step of separating the pressing apparatus from the tilt casting mold after the pressing step and the cooling step; and a casting separation step of separating a casting from the tilt casting mold by separating the cope and the drag after the pressure removing step.
According to the present disclosure, it is possible to immediately perform pressing after tilting by forming a riser on a mold.
Further, by pressing a riser using a hydraulic apparatus, it is possible to prevent molten metal from leaking out of a pressing apparatus and a mold.
Further, a specific compensation for a mold is not required, so it is possible to reduce complexity of designing a mold.
Further, it is possible to reduce quality differences of castings manufactured by tilt casting.
Further, dependence on skillfulness of work is low, so a casting process can be automated.
Further, it is possible to increase productivity of castings per hour by reducing a cooling time of molten metal.
Hereafter, various embodiments of the present disclosure are described with reference to accompanying drawings. However, this is not intended to limit the technology described in the present disclosure to specific embodiments and should be construed as including various modifications, equivalents, and/or alternatives of the embodiments of the present disclosure. In the description of drawings, similar components may be given similar reference numerals.
In the specification, expressions such as “have”, “may have”, “include”, or “may include” indicate existence of corresponding features (e.g., a number, a function, an operation, or a component such as a part) and does not exclude existence of additional features.
In the specification, the terms “A or B”, “at least one of A and/or B”, or “one or more of A and/or B” may include all possible combinations of items to be enumerated. For example, “A or B”, “at least one of A and B”, or “at least one of A or B” may indicate all of cases (1) including at least one A, (2) including at least one B, or (3) including both of at least one A and at least one B.
The terms such as “first” and “second” used in various embodiments may modify various components regardless of the order and/or priority and are used only to discriminate one component from another component without limiting the components. For example, a first user device and a second user device may refer to different user devices regardless of the order or priority. For example, the first component may be named the second component, and vice versa, without departing from the scope of the present disclosure.
When a component (e.g., a first component) is “operatively or communicatively coupled with/to” or “connected to” another component (e.g., a second component), it should be understood that the component may be connected to the another component directly or through another component. However, when a component (e.g., a first component) is “directly coupled to” or “directly connected” to another component (e.g., a second component), it may be understood as another component (e.g., a third component) does not exist between the component and the another component.
The terms used herein “configured to” may be replaced, for example, with “suitable for”, “having the capacity to”, “designed to”, “adapted to”, “made to”, or “capable of”, depending on circumstances. The term “configured to” may not necessarily only mean “specifically designed to” in terms of hardware. Instead, in some circumferences, the term “device configured to” may mean that the device “is capable of doing” with other devices or parts. For example, an expression “processor configured to perform A, B, and C” may mean an exclusive processor (e.g., an embedded processor) for performing the corresponding operations or a generic-purpose processor (e.g., a CPU or an application processor) being capable of performing the corresponding operations by executing one or more software programs stored in a memory device.
Terminologies used herein are used only to describe specific embodiments and may not be intended to limit the range of other embodiments. Singular forms are intended to include plural forms unless the context clearly indicates otherwise. All terminologies used herein including technological or scientific terminologies may have the same meanings that are generally understood by those skilled in the art. Terminologies defined in general dictionaries of the terminologies used herein may be understood as having meanings the same as or similar to the meanings in the contexts and should not be construed as abnormally or exclusively formal meanings unless specifically defined herein. Depending on cases, even the terminologies defined herein should not be construed as excluding the embodiments of the present disclosure.
Various modifications may be achieved by those skilled in the art without departing from the spirit of the present disclosure described in claims, and the modifications should not be understood separately from the spirit or scope of the present disclosure.
According to an embodiment, there is provided a tilt casting mold that includes a cope and a drag, in which when the cope and the drag are combined, a predetermined cavity is formed therein and a riser is formed on a side of the cavity; a pouring cup is coupled to a surface having the riser of the drag; molten material is injected into the pouring cup and then the molten metal in the pouring cup is injected into the cavity by tilting the mold assembly composed of the cope, the drag, and the pouring cup.
The riser includes a channel (an inlet) for injecting molten metal into the cavity, molten metal flows into the cavity through the riser, and the riser may be configured such that a piston of a pressing apparatus to be described below can be accommodated therein. The riser may be one or more and pressing apparatuses corresponding to the number of the riser may be required.
A neck is formed between the riser and the cavity, and the molten material in the riser can be removed from a casting after the molten metal solidifies.
A predetermined cooling water channel may be formed in the tilt casting mold to cool molten metal after the molten metal injection is completed. In this case, it is preferable that the cooling water channel is not formed around the riser or a cooling water channel is formed such that the flow rate of cooling water around the riser is lower than that around the cavity. By this configuration, the cavity is cooled first and then the riser is cooled, whereby it is possible to reduce the quality difference of castings.
It is preferable that the internal volume of the pouring cup (the volume of fluid that can be stored) is larger than the volume of the cavity. The volume of the pouring cup is determined to satisfy “pouring cup volume<cavity volume+riser volume”, whereby it is possible the prevent additional injection of molten metal in a tilting process. Considering contraction of molten metal, it is preferable that the volume of the riser is in the range of 10% to 20% of the volume of the cavity. When the volume of the riser is too small, molten metal contracts even under the neck, so a poor casting may be produced. When the volume of the riser is excessive, the pressing apparatus to be described below is not normally operated, so molten metal may be excessively injected into the riser, causing a waste of cost (raw material).
Further, there is provided a tilt casting apparatus that includes: the tilt casting mold described above, a tilting apparatus injecting molten metal into the cavity by tilting the tilt casting mold at a predetermined speed, and a pressing apparatus pressing the riser and including: a riser cover formed to accommodate the outer surface of the riser of the tilt casting mold and forming a predetermined sealed space including the riser by being fixed to the tilt casting mold; and a piston accommodated inside the riser cover and pressing the riser in the sealed space formed by the riser cover fixed to the tilt casting mold, in which the pouring cup is separated after molten metal is injected into the cavity by operating the tilting apparatus, the riser cover is fixed to the tilt casting mold to accommodate the riser, and then the riser is pressed by the piston.
The configuration in which the riser cover is “formed to accommodate the outer side of the riser of the tilt casting mold” may mean a configuration that fully covers the riser to prevent the molten metal in the cavity under the riser from leaking out of the pressing apparatus or the mold in the pressing process.
Since the tilting apparatus can be easily configured by those skilled in the art by referring to tilting apparatuses in the related art and the specification of the present disclosure, the speed of tilting the mold is not described.
The sealed space means a configuration preventing molten metal from leaking out of the pressing apparatus or the mold, but does not mean blocking particles smaller than the particles of the molten metal such as air or other gas.
When the riser is pressed by the piston as described above, the molten metal in the riser partially comes out of the riser (out of the mold), and the molten metal coming outside is collected in the riser cover. In this state, when the piston keeps pressing the riser (the piston is inserted deeper), external force corresponding to the force applied to the piston is applied to the molten metal under the riser cover, so the molten metal is contracted, whereby a casting that has the same shape as the cavity can be obtained. Through this process, it is possible to produce castings with very small quality differences even without considering compensation due to contraction.
When the riser is pressed by the piston and the inside and outside of the riser cover are fully closed (even a flow of gas is blocked), gas components such as air may be contained in the riser cover. However, since molten metal has been injected in the cavity by the tilt casting method, all gas components including air are positioned at the upper portion in the riser and gas is not mixed into the molten metal. In pressing, gas is also pressed and contracted and the piston uniformly presses the inside of the riser under the riser cover, so the influence of the gas can be ignored. However, the pressing apparatus may further include a vacuum forming unit to reduce the influence of gas when precise machining is required. The inside and outside of the riser cover are blocked from air by bringing the riser cover into close contact with the mold and then the air in the riser cover is removed, whereby the riser cover can be fully filled with molten metal in the pressing process.
The pressing apparatus may further include a hydraulic apparatus that presses the riser cover and the piston such that the pressure applied to the tilt casting mold by the riser cover is larger than the pressure applied to the molten metal by the piston.
The pressing apparatus may include an actuator that brings the riser cover and the tilt casting mold in close contact with each other. As shown in
When sealing between the riser cover and the tilt casting mold is not complete, the molten metal may leak out of the riser cover due to the pressure applied by the piston to the molten metal in the riser. This phenomenon may occur when the force (pressure) between the riser cover and the tilt casting mold is smaller than the force (pressure) between the piston and the molten metal. In order to prevent this phenomenon, it is preferable to control the pressure of the riser cover and the pressure of the piston, as described above.
The hydraulic apparatus may be connected to the riser cover and the piston through a single hydraulic circuit such that the area of a cross-section perpendicular to the pressing direction of the riser cover is larger than that of the piston.
It may be possible to separately provide a hydraulic apparatus for pressing the riser cover and a hydraulic apparatus for pressing the piston and separately control the hydraulic apparatuses, but in this case, the structure of the entire apparatus becomes complicated and control also becomes more complicated, so the possibility of malfunction and breakdown may increase. Accordingly, it is preferable to control the pressures applied to the riser cover and the piston through a single hydraulic circuit, as described above.
Meanwhile, the coupling force between the cope and the drag when the piston presses molten metal may act as a factor for designing a casting process. When the coupling force between the cope and the drag does not increase in proportion to an increase of the pressing force by the piston, a poor casting may be produced due to separation of the cope and the drag, etc.
Accordingly, it may be possible to connect the hydraulic circuit of the hydraulic apparatus also to the cope and the drag in order to solve the problem with the coupling force. As shown in
The force applied to the mold (the cope and the drag) may be configured such that any one of the cope or the drag is fixed and pressure is applied to the other one (the cope or the drag not fixed) through the hydraulic apparatus.
An electromagnet may be disposed on a side of the riser cover such that the pressing apparatus brings the riser cover and the tilt casting mold in close contact with each other when the riser is pressed by the piston.
In the configuration described above, the composition ratio of an alloy of the tilt casting mold may be adjusted (only the portion being in contact with the riser cover may be magnetized) to react with a magnetic body. It is possible to assist coupling of the riser cover and the tilt casting mold through the electromagnet, or it may be possible to seal the riser cover and the tilt casting mold using the electromagnet if the intensity of the electromagnet is large.
By making it easy to couple or separate the tilt casting mold and the riser cover through the hydraulic apparatus, the electromagnet, or the like, there is an effect of automating the process, reducing the production time, etc. However, this configuration may be a super technology (opposite to an appropriate technology) when making a specimen for testing a product or developing a product such as a casting test unlike mass production. Since an installation cost may greatly increase due to the hydraulic apparatus, etc., installation may be an economic burden for subjects (research and development team, etc.) that do not need many castings. Accordingly, there is a need for a configuration that can achieve sealing between the riser cover and the tilt casting mold even without using the hydraulic apparatus described above.
The riser cover and the tilt casting mold may have fasteners corresponding to each other such that the pressing apparatus couples and fixes the riser cover and the tilt casting mold when the piston presses the riser.
The number and position of the fasteners may be adjusted in consideration of the pressure that is applied to molten metal. The fasteners may include mechanical elements that couple and fix two or more members such as bolt-nut, a hook, fitting, which is in the range that can be easily achieved by those skilled in the art by referring to the present disclosure, so it is not described in detail.
According to this configuration, it is possible to achieve an apparatus that takes more time than the time to seal the portion between the riser cover and the tilt casting mold using a hydraulic apparatus, etc., but is less complicated and requires a lower installation cost. It is also possible to achieve the apparatus by combining fasteners, a hydraulic apparatus, an electromagnet, etc.
The pressing apparatus may be configured to start pressing the cavity under the condition of
in which (1) the cross-sectional area of the piston is A, (2) the internal cross-sectional area of the riser cover is B, (3) the insertion depth of the piston in the riser is L1, (4) the internal depth of the riser cover is L2, and (5) the depth of the riser is L3.
In the configuration of an apparatus shown in
Since the volume of molten metal pushed by the piston inserted in the riser is AL1, L2(B−A)=AL1 should be satisfied so that the piston starts to press the molten metal in the cavity.
When the depth of the riser is excessively deep, the amount of molten metal that is injected into the riser is excessively increased, so a loss may be generated. Further, when the depth of the riser is excessively shallow, compression may not be generated due to contact between the piston and the neck. Accordingly, the optimal condition may be 0.8L3≤L2(B−A)≤0.95AL3. Arranging this formula, it becomes
Further, the present disclosure provides a tilt casting method that uses the tilt casting apparatus and includes: a pouring cup coupling step of fixing a pouring cup to the tilt casting mold; a first molten metal injection step of injecting molten metal into the pouring cup after the pouring cup coupling step; a second molten metal injection step of injecting the molten metal in the pouring cup into the cavity using gravity by tilting the tilt casting mold after the first molten metal injection step; a pouring cup separation step of separating the pouring cup from the tilt casting mold after the second molten metal injection step; a pressing preparation step of bringing the riser cover in close contact with the tilt casting mold to accommodate the riser after the pouring cup separation step; a pressing step of pressing the molten metal in the riser by pushing the piston after the pressing preparation step; a cooling step of cooling the molten metal during the pressing step; a pressure removing step of separating the pressing apparatus from the tilt casting mold after the pressing step and the cooling step; and a casting separation step of separating a casting from the tilt casting mold by separating the cope and the drag after the pressure removing step.
According to the tilt casting method described above, it is possible to reduce a cooling speed by additionally forming cooling water channels in comparison to tilt casting of the related art. According to tilt casting of the related art, there is a limit in cooling speed because compensation for contraction should be considered, the complexity of mold design is high, and there are large differences in quality of castings when castings are produced several times. However, the pressing-type tilt casting method described above can remove these problems.
This application is a U.S. National Stage Application of International Application No. PCT/KR2020/017492, filed on Dec. 7, 2020, the entire disclosure of which is incorporated herein by reference for all purposes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2020/017492 | 12/7/2020 | WO |
