Mold shell structure for quickly determining seed crystal remelting condition

Abstract

The utility model discloses a mold shell structure capable of rapidly determining the re-melting condition of seed crystals, and aims to determine the shortest length required by seeding of the seed crystals according to comparison of the re-melting conditions of the seed crystals with different heights. Therefore, the mold shell structure capable of rapidly determining the re-melting condition of the seed crystals comprises a base plate mold shell, a middle column pipe mold shell is arranged in the center of the top of the base plate mold shell, a plurality of seed crystal mold shells are arranged at the top of the base plate mold shell, and seed crystals with different heights are plugged in seed crystal cavities of the seed crystal mold shells in a matched mode. And the side part of the seed crystal is removed, so that a channel for molten metal to flow is formed between the seed crystal cavities.

Description

Technical Field

[0001] This utility model belongs to the field of precision casting technology, and in particular relates to a mold shell structure for quickly determining the remelting condition of seed crystals. Background Technology

[0002] The fabrication technology of high-temperature alloy single-crystal turbine blades can be divided into the seed crystal method and the seed crystal method. The seed crystal method involves placing a pre-selected seed crystal with primary and secondary crystal orientations inside a seed crystal cavity at the bottom of a mold. During heating and holding, the upper part of the seed crystal melts back, and then molten metal is poured in. During solidification, the melt grows epitaxially along the original crystal orientation of the seed crystal, thus obtaining a single-crystal casting with the same crystal orientation. During the fabrication process, if the seed crystal inserted into the bottom of the mold is too short, it will not melt back during holding and will only remain in a solid state, thus failing to achieve phase transfer. Conversely, if the seed crystal is too long, it will result in material waste.

[0003] In summary, determining the minimum length required for seed crystal introduction is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] The main purpose of this invention is to provide a mold shell structure for quickly determining the remelting condition of seed crystals, aiming to determine the shortest length required for seed crystal introduction based on the comparison of the remelting conditions of seed crystals at different heights.

[0005] To address this, the present invention provides a mold shell structure for rapidly determining the remelting status of seed crystals, comprising a base mold shell, a central column mold shell at the top center of the base mold shell, and multiple seed crystal mold shells at the top of the base mold shell. Each seed crystal mold shell has a seed crystal cavity filled with a matching seed crystal, the height of the seed crystals in each seed crystal cavity is inconsistent, and the sides of the seed crystals are depleted, thereby forming a channel for the flow of molten metal between the seed crystal cavities.

[0006] Specifically, the seed crystal mold shells are divided into multiple groups according to their diameters, and each group of seed crystal mold shells contains a seed crystal 4 of varying heights.

[0007] Specifically, each set of seed crystal mold shells is arranged in a circular array on the base mold shell with the central column tube mold shell as the center.

[0008] Specifically, the diameter of the seed crystal cavity is 5-8 mm and the height is 10-60 mm.

[0009] By setting multiple seed crystal molds on the base mold, seed crystals of different heights with oxide scale removed are inserted from the bottom of the base mold into the corresponding seed crystal cavities. The entire mold structure is then placed on a water-cooled copper plate for heating and heat preservation, causing the upper part of the seed crystal to remelt. Afterward, the seed crystals are pulled out, with the pulling distance determined according to the height of the mold. This simulates the actual casting process of seed crystals of different heights, diameters, and alloy types. After the experiment, the shells are removed, the seed crystals are cleaned, and the surface state of the seed crystals is observed and recorded to obtain the shortest seed crystal length required for the seed crystal to remelt.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1. The mold assembly requires no gating system, reducing the difficulty of mold assembly and eliminating the need to prepare a master alloy before the experiment, thus lowering casting costs. Furthermore, compared to conventional casting, the experiment saves time on heating and melting the master alloy and on casting time, and the shorter pulling distance shortens the experimental time.

[0012] 2. By measuring the side of the seed crystal, a flow surface for molten metal to flow is formed, so there is no need to grind, polish, or corrode the seed crystal cross section to observe the metallographic structure to judge the remelting status. The remelting status of the seed crystal can be quickly determined by comparing the surface state of the seed crystal measuring surfaces at different heights.

[0013] 3. Compared to the disadvantage of limited mold assembly space due to the large size of the casting, the seed crystal is relatively small, which greatly increases the number of molds that can be assembled. Multiple sets of seed crystal data with different heights, diameters and alloy types can be obtained in a single experiment. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a front view of the mold shell structure provided in this embodiment of the utility model;

[0016] Figure 2 This is a top view of the mold shell structure provided in this embodiment of the utility model;

[0017] Among them: 1. Chassis mold shell; 2. Central column tube mold shell; 3. Seed crystal mold shell; 4. Seed crystal; 5. Channel. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] See Figure 1 This utility model discloses a mold shell structure for quickly determining the remelting status of seed crystals. The structure includes a base mold shell 1, a central pillar mold shell 2 at the top center of the base mold shell 1, and multiple seed crystal mold shells 3 at the top of the base mold shell 1. Each seed crystal mold shell 3 contains a seed crystal 4 within its seed crystal cavity. The height of the seed crystals 4 within each seed crystal cavity is inconsistent, and the sides of the seed crystals 4 are de-materialized to form channels 5 for the flow of molten metal between the seed crystal cavities. The de-materialization of the seed crystal 4 refers to the operation of removing a portion of the material along the seed crystal axis.

[0022] In this embodiment, multiple seed crystal molds 3 are set on the base mold 1, and seed crystals 4 with different heights and oxide scale removed are inserted into the corresponding seed crystal cavities from the bottom of the base mold 1. Then, the entire mold structure is placed on a water-cooled copper plate and heated and kept at a constant temperature to cause the upper part of the seed crystal 4 to remelt. After that, a pulling operation is performed, and the pulling distance is determined according to the height of the mold to simulate the actual seed crystal casting process. After the directional solidification experiment is completed, the shell is removed and the seed crystal 4 is cleaned. By observing and recording the surface state of the seed crystal, the shortest seed crystal length required for the seed crystal to remelt can be obtained.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The mold assembly requires no gating system, reducing the difficulty of mold assembly. Furthermore, no master alloy needs to be prepared before the experiment, thus lowering casting costs. Compared to conventional casting, this method saves time on heating and melting the master alloy and on casting time, and the shorter pulling distance further reduces casting time.

[0025] By measuring the side of the seed crystal, a flow surface for molten metal is created, eliminating the need to grind, polish, or corrode the seed crystal cross-section to observe the metallographic structure and determine the remelting status. The remelting status of the seed crystal can be quickly determined simply by comparing the surface condition of the measured surfaces at different heights.

[0026] The fabrication process of the aforementioned mold shell structure is as follows: First, a wax model is prepared, then the wax model is dipped in slurry and sand-cast to obtain a preliminary ceramic shell. Next, the preliminary ceramic shell is dewaxed and fired to obtain the aforementioned mold shell structure. The wax model consists of a base, a central column tube, and wax rods of different sizes. Based on the commonly used seed crystal dimensions, the diameter of the wax rods can be controlled between 5-8 mm, and the height between 10-60 mm. Wax rods are evenly welded to the inner and outer rings of the base, and the number of wax rods is adjusted according to the dimensions of the gating system base to ensure a certain gap between the wax rods. After dewaxing, the positions of the wax rods directly constitute the corresponding seed crystal cavities.

[0027] In practical applications, the seed crystal mold shell 3 is divided into multiple groups according to different diameters. Each group of seed crystal mold shell 3 contains a seed crystal 4 of varying height. By modifying the seed crystal material, the actual casting process of seed crystals with different heights, diameters, and materials can be simulated. Compared to the limited mold assembly space caused by the large size of the casting, the relatively small size of the seed crystal greatly increases the number of molds that can be assembled. Multiple sets of seed crystal data with different heights, diameters, and alloy types can be obtained in a single experiment.

[0028] Specifically, each set of seed crystal mold shells 3 is arranged in a circular array on the base mold shell 1 with the central column tube mold shell 2 as the center. This design can ensure the consistency of experimental conditions for each set of seed crystals and improve the reliability of obtaining seed crystal data.

[0029] Application examples

[0030] The mold was assembled using wax rods with a diameter of 6mm and a height of 50mm. DD419 seed crystals with lengths of 25mm, 30mm, 33mm, 36mm, 40mm, 46mm, and 50mm were selected, with a 1.5mm margin removed from the cross-section of each seed crystal. The seed crystals were then cleaned and shelled after the experiment. The top surface of the 25mm high seed crystal was flat, and no molten alloy flow and solidification were observed on the margin. Starting with the 30mm high seed crystal, the top surface became uneven. Due to the melting of the alloy at the top, varying degrees of necking appeared, and the margin was visibly covered by the flowing alloy from above. Therefore, it can be determined that under these casting conditions, the shortest effective length of the seed crystal should be 30mm.

[0031] Unless otherwise stated, if any of the technical solutions disclosed in this utility model discloses a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this utility model discloses only some numerical values ​​to illustrate the technical solutions of the invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0032] Meanwhile, if the present invention discloses or relates to mutually fixedly connected parts or structural components, then unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured by casting) (except where it is obviously impossible to use an integral forming process).

[0033] Furthermore, unless otherwise stated, the terms used to indicate positional relationships or shapes in any of the technical solutions disclosed in this utility model include states or shapes that are similar to, close to, or approximate with those states or shapes. Any component provided by this utility model can be assembled from multiple individual components, or it can be a single component manufactured using a one-piece molding process.

[0034] The above embodiments are merely illustrative examples to clearly illustrate the present invention, and are not intended to limit the implementation. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A rapid determination of the seed crystal remelt situation of the shell structure, comprising a bottom disc shell (1), the top center of the bottom disc shell (1) is provided with a column pipe shell (2), characterized in that: The top of the bottom mould shell (1) is provided with a plurality of seed crystal mould shells (3), each seed crystal cavity of the seed crystal mould shell (3) is matched with a seed crystal (4), the heights of the seed crystals (4) in each seed crystal cavity are inconsistent, and the side of the seed crystal (4) is reduced, so that a channel (5) for metal liquid flowing is formed between the seed crystal cavities.

2. The mold structure for quickly determining the seed crystal remelt condition according to claim 1, wherein: The seed crystal mould shells (3) are divided into groups according to diameters.

3. The mold structure for quickly determining the seed crystal remelt condition according to claim 1, wherein: Each group of the seed crystal mould shells (3) is distributed in a circular array on the bottom mould shell (1) with the center of the column pipe mould shell (2).

4. The seed meltback determination mold structure of any of claims 1-3, wherein: The diameter of the seed crystal cavity is 5-8mm, and the height is 10-60mm.

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