TWI718785B - Method for manufacturing a mold - Google Patents

Abstract

A method for manufacturing a mold is provided to solve the problem where the cured object of the metal liquid injected into the mold would form holes during the curing process. The method includes providing information regarding the locations of the holes of the metal object cured from a metal liquid that is injected into a mold, obtaining information regarding the changes of the locations of the holes during the adjustment of the heat-conducting rate of the mold, and adjusting the heat-conducting rate of the mold to cause the holes of the metal object to move to predetermined locations.

Description

Shell mold manufacturing method

The invention relates to a method for manufacturing a shell mold, in particular to a method for manufacturing a shell mold for casting molten metal to form a predetermined casting.

Generally, in investment casting, wax is used as a material to make a predetermined wax model, and then the wax model is repeatedly dipped in slurry and sand to form a coating layer on the wax model. After solidification, the wax model is dissolved to obtain a hollow shell mold, and finally the molten metal is poured into the hollow shell mold to solidify to obtain a predetermined metal casting. When the molten metal changes from a liquid to a solid state, shrinkage will occur due to thermal expansion and contraction, or because the cooling rate of each part of the metal casting is different, and shrinkage will occur. Usually, for example, an additional cap can be added to the shell mold to perform the molten metal. Supplement to avoid the formation of shrinkage holes, but the addition of supplementary caps will affect the yield and yield of castings, and will also affect the difficulty of forming the shell mold and the cost of post-processing.

In view of this, the conventional investment casting does still have to be improved.

In order to solve the above-mentioned problems, the purpose of the present invention is to provide a shell mold manufacturing method which can improve the casting quality.

The directionality described in the full text of the present invention or its similar terms, such as "front", "rear", "left", "right", "up (top)", "down (bottom)", "inner", "outer" ,"side" And so on, mainly refer to the directions of the attached drawings. The directional or similar terms are only used to assist in the description and understanding of the embodiments of the present invention, and are not used to limit the present invention.

The elements and components described in the full text of the present invention use the quantifiers "one" or "one" for convenience and to provide the general meaning of the scope of the present invention; in the present invention, it should be construed as including one or at least one, and single The concept of also includes the plural, unless it clearly implies other meanings.

Approximate terms such as "combination", "combination" or "assembly" mentioned in the full text of the present invention mainly include the types that can be separated without destroying the components after being connected, or the components cannot be separated after being connected, which are common knowledge in the field Those can be selected based on the materials of the components to be connected or assembly requirements.

The manufacturing method of the shell mold of the present invention includes: providing a position where a shrinkage cavity is generated when a metal casting liquid is solidified in a shell mold; obtaining a change in the position of the shrinkage cavity when the heat transfer rate of the shell mold is adjusted, and changing the shell mold The thickness is used to adjust the heat conduction rate of the shell mold, and obtain the position change of the shrinkage cavity when the shell mold forms a thickened part; and adjust the thickness of the thickened part to adjust the heat conduction rate of the shell mold so that the shrinkage hole is displaced To a predetermined location.

According to this, the shell mold manufacturing method of the present invention measures the change of the shrinkage cavity position after the shell mold is formed with different heat transfer rates, and can determine the shape of the shell mold according to the change, and can be used for manufacturing The shell mold for pouring the metal casting liquid can control the solidification direction of the metal casting liquid in the shell mold to move the shrinkage cavity to a predetermined position, which can achieve the effects of improving the quality of the casting and reducing the cost.

Wherein, the thickness of one of the shell molds is increased by 2 to 7 times to form the thickened portion. In this way, by forming the thickened portion on the shell mold, the shell mold can affect the cooling and solidification of the metal casting liquid to adjust the position of the shrinkage cavity.

Wherein, the shell mold system has a mold cavity and a pouring cavity, and the pouring cavity is connected The casting cavity and the thickening part are located in the pouring cavity. In this way, it has the effect that the shrinkage cavity is completely located in the casting cavity.

Wherein, in the shell mold, the thicker part after the casting is formed is formed with a relatively thin thickness, and the thinner part after the casting is formed in the shell mold is formed with a relatively thicker thickness as the thickened part. In this way, the shrinkage cavity can be avoided in the thicker part after the casting is formed due to the slow cooling rate, and the shrinkage cavity can be moved to other positions, which has the effect of controlling the position of the shrinkage cavity at a specific position. .

Wherein, different parts of the shell mold are formed with high heat conduction materials and low heat conduction materials to adjust the heat conduction rate of the shell mold to obtain the position change of the shrinkage cavity. In this way, it has the effect of controlling the location of the shrinkage cavity at a specific location.

Wherein, the high thermal conductivity material is iron oxide, glass fiber or polyester gypsum, and the low thermal conductivity material is magnesium oxide, zirconium oxide or fused silica. In this way, a more precise temperature gradient can be established, and the solidification direction of the metal casting liquid can be further controlled, and the control accuracy of the shrinkage cavity position can be improved.

Wherein, the part with a relatively thin thickness of the shell mold is formed with a high thermal conductivity material, and the part with a relatively thick thickness of the shell mold is formed with a low thermal conductivity material. In this way, a more precise temperature gradient can be established, and the solidification direction of the metal casting liquid can be further controlled, and the control accuracy of the shrinkage cavity position can be improved.

Among them, a powder supply unit of a 3D spray printing device drops the powder on a working plane, and a powder spreading unit spreads the powder on the working plane, and then a spray printing unit sprays the adhesive to The powder materials are stacked to form the shell mold. In this way, the thickness of each part of the shell mold can be accurately controlled, and the thickened portion can be easily formed at a predetermined position of the shell mold.

1: Shell mold

11: Mold cavity

12: Pouring cavity

2: Thickened part

H: Shrinkage

C1: Low thermal conductivity material

C2: High thermal conductivity material

[Figure 1] A schematic view of a shell mold of a predetermined casting in one of the shell mold manufacturing methods of the present invention.

[Figure 2a] A schematic diagram of shrinkage cavity formation in the shell mold manufacturing method of the present invention.

[Figure 2b] A schematic diagram of the shrinkage cavity of the shell mold manufacturing method of the present invention being moved to the mold cavity and the pouring cavity.

[Figure 2c] A schematic diagram of the shrinkage cavity moved to the pouring cavity in the manufacturing method of the shell mold of the present invention.

[Figure 2d] The shrinkage cavity of the shell mold manufacturing method of the present invention is completely located in the pouring cavity.

[Figure 3] A partial enlarged view of the shell mold of the casting cavity as shown in Figure 1.

[Figure 4] A partial enlarged view of the shell mold of the mold cavity as shown in Figure 1.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, the preferred embodiments of the present invention will be described in detail in conjunction with the accompanying drawings as follows: A preferred embodiment of the present invention The manufacturing method of the shell mold includes providing a position where a shrinkage cavity is generated when a metal casting liquid is solidified in a shell mold 1, and adjusting the temperature gradient in the shell mold 1 so that the shrinkage cavity is displaced to a predetermined position.

Please refer to Figures 1 and 2a, the shell mold 1 has a mold cavity 11, and the shape of the mold cavity 11 can be the same as the shape of a predetermined casting, so that the metal can be The casting liquid is poured into the casting cavity 11 so that the metal casting liquid can be formed into the predetermined casting after solidification. The shell mold 1 may have a casting cavity 12 connected to the casting cavity 11 , The metal casting liquid can flow from the pouring cavity 12 into the casting cavity 11. When the metal casting liquid is solidified and formed in the casting cavity 11, it will expand and contract due to heat or cool down at various parts of the casting. The difference in speed results in a shrinkage cavity H. At this time, the position at which the shrinkage cavity H is generated in the casting can be obtained.

Please refer to Figure 2a. For example, the position of the shrinkage cavity H can be known by actually pouring the metal casting liquid into the casting cavity 11, and after the metal casting liquid is solidified and formed, or, The conventional simulation software (for example, FLOW 3D Cast) can be used to simulate the location of the shrinkage cavity H after the metal casting liquid is formed in the shell mold 1. This is a common method used by those in the art, and the present invention will not be repeated here.

Please refer to Figures 2b~2d. When the metal casting liquid is poured into the shell mold 1 and begins to cool and solidify, a temperature gradient will be formed in the shell mold 1 due to the influence of the shell mold 1, that is, by Due to the difference in the heat conduction rate of the shell mold 1, the metal casting liquid will have different cooling rates in the shell mold 1. For example, the thickness of the shell mold 1 can be adjusted to make the shell mold 1 have different heat conduction rates. The following is an example of simulation by the above simulation software, which can be formed anywhere on the shell mold 1. The thickness is changed to change the heat transfer rate there. For example, the thickness of the shell mold 1 may be increased to reduce the heat transfer rate, or the thickness of the shell mold 1 may be reduced to increase the heat transfer rate. In this embodiment, the shell mold 1 can be formed with a thickened portion 2, that is, the shell mold 1 has a relatively large thickness on the thickened portion 2, preferably with a thickness facing the outside of the shell mold 1. The thickness of the shell mold 1 is increased in the direction to form the thickened portion 2, thereby avoiding the influence of the cavity shape in the shell mold 1. In detail, the shell mold 1 can have a uniform thickness. When the mold 1 forms the thickened portion 2, the thickened portion 2 may have a relatively large thickness. In this embodiment, the thickness of one of the shell molds 1 is increased by 2 to 7 times to form the thickened portion 2. It is worth noting that when the metal casting liquid is poured into the shell mold 1 and begins to cool and solidify, the cooling time of the metal casting liquid at the relatively thick wall of the shell mold 1 is relatively slow, and the cooling time is relatively slow, and the cooling time is relatively slow. The metal casting liquid at the relatively thick wall of the shell mold 1 will produce internal shrinkage after cooling and solidification. Therefore, the thickened portion 2 can be formed on the shell mold 1 so that the shell mold 1 can be aligned The cooling and solidification of the metal casting liquid affects the adjustment of the position of the shrinkage cavity H. In addition, it is also possible to reduce the thickness of the shell mold 1 so that the cooling time of the metal casting liquid at the relatively thin wall of the shell mold 1 is relatively fast, and the shrinkage cavity H is not easily generated. The position of the shrinkage cavity H can be adjusted by affecting the cooling and solidification of the metal casting liquid, and the present invention is not limited.

In detail, the thickened portion 2 may be located outside the mold cavity 11, That is, the thickened portion 2 is not positioned in the mold cavity 11. In this embodiment, the thickened portion 2 is positioned in the casting cavity 12. After the metal casting liquid is cooled and solidified in the shell mold 1, The location of the shrinkage cavity H can be distributed in the mold cavity 11 and the casting cavity 12 (as shown in Figure 2b). When the thickness of the thickened portion 2 is increased, the shrinkage cavity H can be known The forming position in the casting gradually moves toward the pouring cavity 12, and finally the metal casting liquid can be cooled and solidified in the shell mold 1. The shrinkage cavity H is completely located in the pouring cavity 12 (as shown in Figure 2d), Wherein, the worker can adjust the position and thickness of the thickening part 2 by a false trial method to finally obtain the shell mold 1 that can make the shrinkage hole H completely located in the casting cavity 12, or can use the aforementioned conventional software Simulating the shifting position of the shrinkage cavity H formed by the change of the thickened portion 2 can reduce the consumption of materials and have the effect of saving costs. In addition, the shell mold 1 can also be formed into a relatively thin thickness for the part located in the mold cavity 11, so that after the metal casting liquid is cooled and solidified in the shell mold 1, the shrinkage cavity H will not be formed in The mold cavity 11 is located in the pouring cavity 12. Thereby, the relative change in thickness can be formed by the shell mold 1, so that the metal casting liquid can form different cooling rates in the shell mold 1 to have the temperature gradient, and the temperature gradient can cause the metal casting The liquid produces a directional solidification, that is, the metal casting liquid can form different parts of the shell mold 1 with a cooling rate from fast to slow, so that the cooling rate is slow (the relatively thick part of the shell mold 1, namely , The thickened portion 2) generates the shrinkage hole H, and controls the position of the shrinkage hole H to be moved to the casting cavity 12. According to this, the worker can actually perform the metalization of the shell mold 1 obtained by the aforementioned method. The casting of the casting liquid can remove the shrinkage cavity H at the same time during the modification operation of the pouring port after the metal casting liquid is cooled and formed, leaving a complete casting without the shrinkage cavity H.

In addition, the thickened portion 2 of the shell mold 1 can be designed to further match the shape of the casting. For example, the thicker part of the shell mold 1 can be formed with a relatively thin thickness after the casting is formed. And in the shell mold 1 in the thinner part after the casting is formed, a relatively thicker thickness is formed as the thickened part 2, thereby avoiding the occurrence of the thicker part after the casting is formed due to the slower cooling rate. Shrinkage hole H, and make the shrinkage hole H move to other positions, and have the shrinkage hole H produced The role of birth control in a specific part.

Please continue to refer to Figures 1, 3, and 4. In addition, it is also possible to use materials with different thermal conductivity to form different parts of the shell mold 1 to adjust the heat transfer rate of the shell mold 1, for example, A low thermal conductivity material C1 can be used to form a part of the shell mold 1, so that the cooling time of the metal casting liquid at the low thermal conductivity material C1 is relatively slow, and the shrinkage cavity H will be generated after cooling and solidification, for example The low thermal conductivity material C1 can be used to form the shell mold 1 of the casting cavity 12, or a high thermal conductivity material C2 can be used to form a part of the shell mold 1, so that the metal casting liquid is located at the high thermal conductivity material C2. The time is relatively fast. For example, the high thermal conductivity material C2 can be used to form the shell mold 1 of the mold cavity 11, and the shrinkage cavity H is not easily generated. The high thermal conductivity material C2 can be iron oxide, glass fiber, poly Ester gypsum, etc., the low thermal conductivity material C1 can be magnesium oxide, zirconia, fused silica, etc. The present invention is not limited, and the high thermal conductivity material C2 and the low thermal conductivity material C1 can also be mixed to form an intermediate value The thermal conductivity of the mixed material is used to further adjust the thermal conductivity of the shell mold 1. Thereby, the shell mold 1 can be formed of materials with different heat conduction, so that the metal casting liquid forms a different cooling rate in the shell mold 1 to have the temperature gradient, and cause the metal casting liquid to produce directional solidification.

It is worth noting that a more precise temperature gradient can be formed by changing the relative thickness of the shell mold 1 and different heat conducting materials at the same time. For example, the thinner part of the shell mold 1 is formed by the high thermal conductivity material C2 to increase the cooling rate of the thick part after the casting is formed, and the thicker part of the shell mold 1 is formed by the low thermal conductivity material C1. In this way, a more precise temperature gradient can be established to further control the solidification direction of the metal casting liquid and improve the control accuracy of the shrinkage cavity H position.

According to the aforementioned shell mold 1, the shell mold 1 can be made by a 3D printing device, which can drop, for example, ceramic powder on a working plane through a powder supply unit of the 3D printing device, and a powder spreader The unit flattens the powder on the working plane, and then a spray printing unit performs the adhesive Spraying, by this, is repeated to form the shell mold 1 by stacking powder materials. In this way, the thickness of each part of the shell mold 1 can be accurately controlled, and the thickened portion 2 can be easily formed at a predetermined position of the shell mold 1. In addition, by replacing the powder material of the powder supply unit, the parts of the shell mold 1 can be formed with the high thermal conductivity material C2 powder material and the low thermal conductivity material C1 powder material to establish a more precise temperature gradient.

In summary, the shell mold manufacturing method of the present invention measures the change of the shrinkage cavity position after the shell mold has formed different heat transfer rates, and can determine the shape of the shell mold according to the change, and can be used to manufacture The shell mold used for pouring the metal casting liquid can control the solidification direction of the metal casting liquid in the shell mold to move the shrinkage cavity to a predetermined position, which can achieve the effects of improving the quality of the casting and reducing the cost.

Although the present invention has been disclosed using the above-mentioned preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with the art without departing from the spirit and scope of the present invention may make various changes and modifications relative to the above-mentioned embodiments. The technical scope of the invention is protected. Therefore, the scope of protection of the invention shall be subject to the scope of the attached patent application.

1: Shell mold

11: Mold cavity

12: Pouring cavity

2: Thickened part

H: Shrinkage

Claims (8)

A method for manufacturing a shell mold includes: providing a position where a shrinkage cavity is generated when a metal casting liquid is solidified in a shell mold; obtaining a change in the position of the shrinkage cavity when the heat transfer rate of the shell mold is adjusted, and changing the thickness of the shell mold to Adjust the heat conduction rate of the shell mold, and obtain the position change of the shrinkage cavity when the shell mold forms a thickened portion; and adjust the thickness of the thickened portion to adjust the heat conduction rate of the shell mold so that the shrinkage cavity is displaced to a Reservation location. Such as claim 1, wherein the thickness of one of the shell molds is increased by 2 to 7 times to form the thickened portion. The shell mold manufacturing method of claim 1, wherein the shell mold has a mold cavity and a pouring cavity, the pouring cavity is connected to the mold cavity, and the thickening part is located in the pouring cavity. The shell mold manufacturing method of claim 1, wherein the thicker part of the shell mold is formed with a relatively thin thickness after the casting is formed, and the thinner part after the casting is formed in the shell mold is formed with a relatively thinner thickness. The thicker thickness serves as the thickened portion. For example, the shell mold manufacturing method of claim 1, wherein the different parts of the shell mold are formed with a high thermal conductivity material and a low thermal conductivity material to adjust the thermal conduction rate of the shell mold to obtain the position change of the shrinkage cavity. According to claim 5, the shell mold manufacturing method, wherein the high thermal conductivity material is iron oxide, glass fiber or polyester gypsum, and the low thermal conductivity material is magnesium oxide, zirconium oxide or fused silica. The shell mold manufacturing method of claim 5, wherein the relatively thin part of the shell mold is formed of a high thermal conductivity material, and the relatively thick part of the shell mold is formed of a low thermal conductivity material. Such as the shell mold manufacturing method of any one of claims 1 to 7, wherein, through a 3D A powder supply unit of the spray printing device drops the powder on a working plane, and a powder spreading unit spreads the powder on the working plane, and then a spray printing unit sprays the adhesive to form the powder stack. The shell mold.

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