KR20170041622A - Casting method and gate structure of casting mold - Google Patents

Abstract

The present invention relates to a casting method, and a gate structure of a casting mold. The present invention relates to the gate structure of the casting mold, and the casting method restraining a flow shape of molten metal introduced to a casting mold to generate a uniform tissue. According to the present invention, the casting method casts a casting by allowing the molten metal to be introduced to a cavity of the casting mold through a plurality of gate units.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method and a casting mold,

The present invention relates to a casting method and a sprue mold structure of a casting mold, and relates to a casting method capable of forming a uniform structure by restricting the flow form of the molten metal flowing into the casting mold and a sprue structure of the casting mold.

In recent years, mobile phones such as smart phones have been manufactured in a thin form. In order to apply such a large-sized thinned-out structure, it is necessary to secure the strength of the structure. In order to secure the strength of the structure, a metal material is used as an inner / outer case of the portable terminal.

Particularly, the external part of the portable terminal is directly recognized by the tactile sense or sight of the user, and various materials can be applied to enhance the aesthetic function, the sensitivity quality, and differentiate from other products. However, depending on the characteristics of the exterior material, there is a restriction in applying various exterior materials because the manufacturing cost may deteriorate due to the processing conditions and processing methods.

Japanese Patent Application Laid-Open No. 10-0703491 and Japanese Patent Application Laid-Open No. 10-2008-0112848 disclose a method of manufacturing a portable terminal case made of metal. According to the conventional metal case manufacturing method, a metal case is made of nickel (Ni), copper (Cu), titanium (Ti) and steel. In recent years, anodizing Processing.

On the other hand, the metal material can be processed into a specific shape such as a case for a portable terminal by a method such as CNC machining. However, if CNC processing is applied to a case for a mobile terminal, the processing time is long, the production cost is increased, and the productivity is decreased. In order to solve such a problem, it is possible to manufacture a case by casting a metal melt, but in this case, as the flow of the molten metal is not linear and a flow such as vortex occurs or a flow distance becomes long, There is a fear that an unbalanced structure is formed, and the quality of the anodizing and the quality of the case are lowered.

It is an object of the present invention to provide a casting method capable of improving the quality of a casting product by uniformly forming a structure of a casting casting, and a gantry structure of a casting mold.

In order to achieve the above object, a casting method of the present invention casts a casting through a plurality of gates to allow a molten metal to flow into a cavity of the casting mold.

According to another aspect of the present invention, there is provided a casting mold sprinkler structure, comprising a runner into which a molten metal is introduced into a cavity through a plurality of gates and a molten metal is transferred to the cavity, and at least two of the plurality of gates, .

The cavity is formed in a rectangular shape having four corner portions, and the gate portion is formed at a position corresponding to two corner portions or four corner portions, respectively.

The runner may include a first main runner protruding in one direction from a charging port into which the molten metal is charged, and a second main runner extending from the charging port in another direction A second runner protruding from the first main runner, a first runner protruding from the first main runner and connected to the gate portion, a second runner protruded from the first main runner and connected to the gate portion, A third runner protruding from the main runner and connected to the gate portion and a fourth runner protruding from the second main runner and connected to the gate portion, the lengths of the first main runner and the second main runner being And the first to fourth runners are respectively connected to different gate portions and have the same length.

According to another aspect of the present invention, there is provided a casting mold comprising: a casting mold having a casting mold, a casting mold for casting a molten metal into a cavity through two gates, and a rinse for transferring the molten metal to the cavity, the cavity being formed in a rectangular shape having four corners, The two gate portions are formed symmetrically with respect to the cavity at the corner of the cavity, and the distance between the two gate portions is equal to the short axis length of the cavity.

The casting method and casting mold of the casting mold according to the present invention allow the molten metal to flow into the cavity through the plurality of gates to produce a dense and uniform casting structure to facilitate anodizing and improve the quality of the casting product .

1 is a perspective view of a casting mold for manufacturing a metal case for a portable terminal according to a first embodiment of the present invention;
FIG. 2 is a perspective view showing a lower mold and an upper mold separated from each other according to a first embodiment of the present invention. FIG.
FIG. 3 is a perspective view of another embodiment showing a lower mold and an upper mold separated from each other according to the first embodiment of the present invention; FIG.
4 is a plan view of a lower mold according to a first embodiment of the present invention;
5 is a perspective view of a case and an additional molding formed by the casting mold according to the first embodiment of the present invention.
6 is a plan view of a lower mold according to a second embodiment of the present invention;
7 is a perspective view of a case and an additional molding molded by a casting mold according to a second embodiment of the present invention;

In the casting method according to the embodiment of the present invention, casting is performed by causing the molten metal to flow into the cavity of the casting mold through a plurality of gate portions, and the casting surface is anodized to form an oxide film. By allowing the molten metal to flow into the cavity through the plurality of gate portions as described above, the structure of the casting can be uniformly generated, thereby facilitating the anodizing process and improving the quality of the casting product.

Hereinafter, a casting mold according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1st Example

The casting mold according to the first embodiment of the present invention comprises a lower mold 110 and an upper mold 200 as shown in FIGS. 1, the upper mold 200 is coupled to the upper portion of the lower mold 110, and a cavity is formed between the lower mold 110 and the upper mold 200. A gate 120 and a runner 130 are formed on the lower mold 110. The upper mold 200 is provided with an injection port 210 for injecting molten metal.

2, a core 110 is protruded from the upper mold 110 and a groove 220 is formed at a lower portion of the upper mold 200 as shown in FIG. An upper mold 200 is coupled to an upper portion of the lower mold 110 to form a cavity between the lower mold 110 and the upper mold 200. That is, the cavity is formed between the core portion 110 and the groove portion 220. The metal melt is injected into the cavity to form the case for the portable terminal. The cavity is formed in a rectangular shape having four corner portions 230, and the case is formed along the shape of the cavity so as to surround the outer frame of the portable terminal.

The gate part 120 is formed at a position corresponding to each of the four corner parts 230 of the cavity, and serves as an inlet through which the molten metal is injected into the cavity. 4, the gate portion 120 includes a first branch portion 121 and a second branch portion 122 that are branched in two directions along the cavity centering on the corner portion 230, The first branch portion 121 is longer than the second branch portion 122. In other words, the cavity is formed in a substantially rectangular shape, and the first branch portion 121 is formed to face the major axis direction of the cavity centering on one of the corner portions 230, and the second branch portion 122 is formed in the minor axis direction As shown in FIG.

The runner 130 formed on the upper part of the lower mold 110 is connected to the injection port 210 to transfer the molten metal to the cavity. The runner 130 includes a first main runner 131, a second main runner 132, a first runner 133, a second runner 134, a third runner 135 and a fourth runner 136 .

The first main runner 131 protrudes in one direction from the input port 210 and the second main runner 132 protrudes from the input port 210 in another direction. The lengths of the first main runner 131 and the second main runner 132 are the same.

The first runner 133 protrudes from the first main runner 131 and is connected to the gate 120. The second runner 134 protrudes from the first main runner 131 and is connected to the gate 120 And the third runner 135 protrudes from the second main runner 132 and is connected to the gate 120. The fourth runner 136 protrudes from the second main runner 132, Lt; / RTI > The first through fourth runners 136 are connected to different gate portions 120 and have the same length.

5 (a) is a view showing a case formed by a casting mold according to an embodiment of the present invention.

The runner 130 having the above-described structure has uniform structure of the case formed in the cavity by matching the injection amount, injection timing, and flow distance of the molten metal injected into the cavity through the respective gate portions 120 under the same conditions Respectively.

Meanwhile, although not shown separately, the present invention may be configured such that the molten metal is injected into the cavity through the two gate portions, unlike the above embodiment. At this time, the gate portions are formed in two corner portions facing each other in the diagonal direction. The gate portion is connected to the input port by a runner, and the two runners connecting the gate portion and the input port may have different lengths.

5 (b) is a view showing a case formed by a casting mold according to another embodiment of the present invention.

On the other hand, before the molten metal is injected into the casting mold as described above, a release agent is sprayed on the surface of the cavity to form an oil film on the surface of the cavity. Accordingly, the molten metal can be prevented from being soldered to the cavity, so that the molded product can be easily separated from the casting mold. In addition, an oil film can be formed by spraying a release agent to the molten metal moving path of the charging port. At this time, the releasing agent injected into the cavity and the releasing agent injected into the inlet are made of different components.

The mold release agent injected into the cavity needs to be limited in order to facilitate separation of the molded article and to prevent degradation of the anodizing quality of the molded article formed in the cavity. Further, since the additional molding formed at the inlet of the molded product to be molded in the cavity does not need to consider the anodizing quality, it is necessary to focus on the separation of the additional molding from the mold release agent injected into the passage of the molten metal at the inlet. As described above, before the molten metal is injected into the casting mold, different release agents are sprayed to the cavity and the injection port to form an oil film, thereby preventing fusion of the molten metal and facilitating the separation of the molded product, thereby enabling continuous casting.

Hereinafter, a method of manufacturing a metal case for a portable terminal using the above-described casting method and a casting mold having a casting mold structure will be described. The method for manufacturing a metal case for a portable terminal according to an embodiment of the present invention includes a mold heating step, a casting step, a cooling step, a pressing step, a strength improving step, a post-treatment step, and an anodizing step.

The mold heating step heats the casting mold of the present invention. Specifically, in the mold heating step, a heating block having a heating coil is disposed in the lower mold and the upper mold, respectively, to heat the casting mold into which the molten metal is injected. In the mold heating step, the temperature of the casting mold is measured by a temperature sensor, and the heating coil is controlled according to the temperature of the casting mold to keep the temperature of the casting mold constant. By heating the casting mold in this manner, it is possible to improve the unevenness of the solidification structure that may occur due to the temperature difference between the molten aluminum alloy and the casting mold.

In the casting step, the aluminum alloy molten metal is injected into the casting mold to mold the case. In the casting mold, the flow of the molten metal in the cavity is made straight and the flow distance is shortened, so that the thermal imbalance is minimized according to the position of the molten metal flow and a uniform structure is formed. If the flow of the molten metal is not linear and a flow such as vortex is generated or the flow distance is long, an unbalanced structure may be formed depending on the time and position of solidification of the molten metal, and the quality of the anodizing may be deteriorated.

In such a casting step, before the molten metal is injected into the casting mold, the releasing agent of different component is injected to the surface of the cavity and the injection port to form an oil film on the surface of the cavity and the passage of the molten metal in the injection port, whereby the molten metal is soldered So that the molded product can be easily separated from the casting mold.

In the cooling step, the aluminum alloy molten metal is injected into the casting mold to cast the case, and the case is cooled by cooling in the water-cooling system. In the above-described casting step, the case is die-casted under high-temperature and high-pressure conditions of 500 ° C or higher and 80 MPa or higher, and quenched by cooling water of 40 ° C or lower. The temperature of the cooling water may rise as the case is cooled, and the temperature of the cooling water initially supplied is 20 to 25 ° C. As described above, by rapidly cooling the case by the water cooling method, a dense and uniform structure can be formed as compared with the air cooling method.

The pressing step removes unnecessary parts after the case molding.

The strength improving step increases the strength of the case by pressing the case. More specifically, a linear pressure is applied toward the case. That is, the inner side of the case is supported by the pressing metal mold, and the outer side of the case is pressed in the inward direction to press it, thereby enhancing the strength of the case. The pressing force applied to the case may act linearly toward any one of the outer surfaces of the case or may act on various parts of the outer surface of the case at the same time. Through this strength improvement step, the case has an elongation before plastic deformation of about 15 to 25%, but a plastic deformation after elongation of less than about 10%.

In the post-processing step, CNC machining, sanding and buffing are performed on the parts requiring precision.

Thereafter, the surface of the case is anodized according to the anodizing step to form an oxide film.

In this manner, CNC machining can be minimized to lower the production cost and shape the productivity, and the anodizing quality can be improved while increasing the strength of the case.

The case for a portable terminal as described above can be manufactured from various metal materials. Among these various metal materials, a case for a portable terminal can be manufactured with an aluminum alloy. The aluminum alloy may contain 1 to 3 wt% of manganese (Mn), 0.01 to 0.5 wt% of zirconium (Zr), 0.01 to 0.5 wt% 0.01 to 1% by weight of silicon (Si), 0.01 to 1% by weight of magnesium (Mg), and the balance aluminum (Al).

In order to improve the anodizing quality, the purity of aluminum must be increased. However, aluminum having high purity is not suitable for the case of the body of the portable terminal because of its low strength. Accordingly, an aluminum alloy which is easy to anodize while increasing its strength is required.

In order to increase the strength of aluminum, an additive added to aluminum has a problem in that the strength of aluminum is increased and the purity of aluminum is lowered, so that the quality of anodizing is drastically deteriorated. Therefore, the additives that make aluminum alloys in addition to aluminum should be strictly limited.

When the weight ratio of manganese (Mn) is less than 1%, the fluidity of the molten aluminum alloy is poor, and the mold is disadvantageously removed, making it difficult to cast a high-quality case. On the other hand, as described above, since the purity of aluminum is lowered as the ratio of the additive increases, the weight ratio of manganese is increased to 1 To 3%.

Zirconium (Zr) and titanium (Ti) improve the fluidity of the molten metal by making the crystal grains of the aluminum alloy finer. If the weight ratio of zirconium and titanium exceeds 0.5%, the zirconium and titanium are not sufficiently dissolved and exist in a heterogeneous structure, and thus the fluidity of the aluminum alloy melt deteriorates. Accordingly, the weight ratio of zirconium to titanium was limited to 0.01 to 0.5%, respectively.

Silicon (Si) and magnesium (Mg) are included as constituents of the aluminum alloy, and the strength of the aluminum alloy can be increased. However, since such silicon and magnesium may lower the anodizing quality, it is necessary to limit the weight ratio to 0.01 to 1%, respectively.

On the other hand, the aluminum alloy may further comprise at least one of copper (Cu) and iron (Fe). However, since copper and iron are also factors that lower the quality of anodizing, the weight ratio of copper (Cu) contained in the aluminum alloy is limited to 0.05% or less and the weight ratio of iron (Fe) is limited to 0.2% or less.

These aluminum alloys are produced in a billet form through continuous casting in order to minimize the addition of impurities.

Preferably 1 to 3% by weight of manganese, 0.01 to 0.5% by weight of zirconium, 0.01 to 0.5% by weight of titanium, 0.01 to 1% by weight of silicon and 0.01 to 1% by weight of magnesium, By weight and the balance aluminum constitutes an aluminum alloy.

Second Example

The casting mold according to the second embodiment of the present invention is composed of the lower mold 110 and the upper mold 200 as in the first embodiment. The upper mold 200 is coupled to the upper portion of the lower mold 110 and a cavity is formed between the lower mold 110 and the upper mold 200. A gate 120 and a runner 130 are formed on the lower mold 110. The upper mold 200 is provided with an injection port 210 for injecting molten metal.

The second embodiment differs from the first embodiment in the structure of the gate portion 120 and the runner 130, so that the gate 120 and the runner 130 will be described. Please refer to Fig. 6 to Fig.

The gate portion 120 according to the second embodiment is formed of two pieces, and is formed at the corner portion of the cavity formed in a rectangular shape. The two gate portions 120 are formed symmetrically about the cavity, and the distance between the two gate portions 120 is the same as the short axis length of the cavity. That is, the two gate portions 120 formed at the corner portion of the cavity are formed so as to minimize the mutual distance.

The runner 130 is formed on the upper portion of the lower mold 110 and connected to the inlet 210 to transfer the molten metal. 6, the runner 130 according to the second embodiment includes a first main runner 131, a second main runner 132, a first runner 133, and a second runner 134 .

The first main runner 131 protrudes in one direction from the input port 210 and the second main runner 1332 protrudes from the input port 210 in another direction. The lengths of the first main runner 131 and the second main runner 132 are the same.

The first runner 133 protrudes from the first main runner 131 and is connected to one of the gate portions 120. The second runner 134 protrudes from the second main runner 132, (120). The lengths of the first and second runners 133 and 134 are the same.

The structure of the runner 130 according to the second embodiment is a structure that minimizes the movement distance of the molten metal introduced into the gate 120 from the input port 210. This minimizes the consumption of the molten metal, You can minimize the need to remove it. Therefore, the position of the inlet 210 is preferably formed near the two gate portions 120, and the distance between the inlet 210 and the two gate portions 120 is the same.

Except for the above-described points, the present embodiment is the same as the first embodiment, and a detailed description thereof will be omitted.

The casting method according to the present invention and the sprue mold structure of the casting mold are not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea of the present invention.

100: lower mold, 110: core portion, 120: gate portion,
121: first minute base, 122: second minute base, 130: runner,
131: first main runner, 132: second main runner, 133: first runner,
134: second runner, 135: third runner, 136: fourth runner,
200: upper mold, 210: inlet, 220: groove,
230: corner portion, C: case,

Claims (5)

And casting the casting by causing the molten metal to flow into the cavity of the casting mold through a plurality of gate portions. And a runner for introducing the molten metal into the cavity through a plurality of gate portions and delivering the molten metal to the cavity,
Wherein at least two gate portions of the plurality of gate portions are formed to face each other. The method of claim 2,
Wherein the cavity is formed in a rectangular shape having four corner portions,
Wherein the gate portion is formed at a position corresponding to each of two corner portions or four corner portions of the casting mold. The method of claim 3,
The gate portion is formed at a position corresponding to each of the four corner portions,
In the runner,
A first main runner protruding in one direction from a charging port into which molten metal is charged;
A second main runner protruding from the input port in another direction,
A first runner projecting from the first main runner and connected to the gate portion,
A second runner projecting from the first main runner and connected to the gate portion,
A third runner projecting from the second main runner and connected to the gate portion,
And a fourth runner projecting from the second main runner and connected to the gate portion,
The lengths of the first main runner and the second main runner are the same,
Wherein the first to fourth runners are connected to different gate portions and have the same length. And a runner for introducing the molten metal into the cavity through the two gate portions and delivering the molten metal to the cavity,
Wherein the cavity is formed in a rectangular shape having four corner portions,
Wherein the two gate portions are formed symmetrically with respect to the cavity at an edge portion of the cavity,
Wherein a distance between the two gate portions is equal to a length in the short axis direction of the cavity.

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