A single crystal blade mischcrystal control method

Abstract

This invention discloses a method for controlling impurities in single-crystal blades. An adjustable heat-insulating baffle is positioned in the cold zone below the heat-insulating carbon felt in a directional solidification furnace, with its leading edge close to the blade body of the blade shell. A control module is connected to the adjustable heat-insulating baffle. The control module includes a drive unit controlled by a preset program. During the directional solidification of the blade shell, when the edge plate of the blade shell enters the transition area between the heat-insulating carbon felt and the adjustable heat-insulating baffle, the control module drives the adjustable heat-insulating baffle to move below the edge plate, providing heat insulation and preventing premature cooling of the edge plate tip. During the shell's descent, the control module controls the adjustable heat-insulating baffle to extend or retract, moving it below the heat-insulating carbon felt to prevent obstruction of the shell's descent. This invention can effectively control impurities in the edge plate of single-crystal blades, resulting in blades with a complete single crystal structure from the blade body to the edge plate.

Description

Technical Field

[0001] This invention relates to the field of precision casting technology, and in particular to a method for controlling impurities in single-crystal blades. Background Technology

[0002] During the directional solidification process of single-crystal blades, the transversely protruding structure of the rim plate easily induces impurities. This disrupts the integrity of the single crystal, resulting in defective blades that are scrapped. Controlling impurity defects in the rim plate or other similar transversely protruding structures is one of the key technologies in the fabrication process of single-crystal blades. Impurity defect control is closely related to the temperature field, which is the result of matching the casting equipment and the mold shell process. When the blade size is small, mold shell process optimization is usually used, including optimizing the thickness of local areas of the mold shell to adjust the temperature field (CN117564225A). However, when the blade size is large, this approach may not be effective due to the large shadow below the rim plate. The industry mostly uses a wax mold guide strip structure to guide the nucleation of the rim plate tip from below. This approach can form small-angle grain boundaries in the rim plate, which may also lead to a decrease in yield. Currently, there is a lack of good solutions for the potential problem of impurities in the rim plates of large-sized blades in the industry.

[0003] The temperature field in a directional solidification furnace has a significant impact on solidification. Traditional casting furnace designs, such as... Figure 1 As shown, graphite rigid felt insulation is typically used between the upper and lower temperature zones (hot and cold zones). This insulation device can effectively reduce heat radiation between the upper and lower temperature zones (in a vacuum furnace, heat radiation is the primary heat transfer method). However, graphite rigid felt usually needs to be replaced during furnace cooling and is costly. It is not feasible to install a matching rigid felt for each module. Therefore, flexible conformal insulation devices, such as graphite paper, are introduced. These devices aim to minimize the gap between the mold shell and the insulating carbon felt, blocking heat radiation between the upper and lower temperature zones. However, after the lower surface of the flange passes through the insulation plate into the cold zone, the tip dissipates heat faster due to geometry, thus forming an overcooled area that is prone to the formation of impurities. Summary of the Invention

[0004] The main objective of this invention is to provide a method for controlling impurities in single-crystal blades, aiming to achieve effective control of impurities in the blade edge plate and obtain blades with complete single crystals from the blade body to the edge plate.

[0005] To address this, the present invention provides a method for controlling impurities in single-crystal blades, comprising the following steps: Step 1: Arranging an adjustable heat-insulating baffle in the cold zone below the heat-insulating carbon felt of the directional solidification furnace, such that the leading edge of the adjustable heat-insulating baffle is close to the blade body of the blade shell; Step 2: Connecting a control module to the adjustable heat-insulating baffle, wherein the control module includes a drive unit controlled by a preset program; Step 3: During the directional solidification of the blade shell, when the edge plate of the blade shell enters the transition area between the heat-insulating carbon felt and the adjustable heat-insulating baffle, the control module drives the adjustable heat-insulating baffle to move below the edge plate to insulate and maintain the edge plate, preventing premature cooling of the edge plate tip; Step 4: During the shell descent stage, the control module controls the adjustable heat-insulating baffle to extend and retract, so that it enters below the heat-insulating carbon felt to prevent obstruction of the shell's descent; when the blade shell continues to descend until the edge plate is completely in the cold zone, the control module drives the adjustable heat-insulating baffle to reset.

[0006] Specifically, the heat-insulating carbon felt divides the furnace cavity of the directional solidification furnace into a hot zone and a cold zone, and a conformal flexible heat-insulating plate is also provided above the heat-insulating carbon felt.

[0007] Specifically, the conformal flexible insulation board is graphite paper.

[0008] Specifically, multiple adjustable heat insulation baffles are evenly arranged side by side around the blade portion.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] This invention employs an adjustable heat-insulating module single-crystal preparation technology, abandoning the method of controlling impurities with crystal guides, thus avoiding the risks of small-angle grain boundaries and recrystallization. A high-temperature resistant vacuum motor controls the adjustable heat-insulating module to achieve heat insulation in this region. Before the rim plate enters the transition zone between the upper and lower temperature zones, it is placed below the rim plate for heat preservation, preventing premature cooling of the rim plate tip. During the mold shell descent stage, the control motor controls the extension and retraction of the adjustable heat-insulating baffle, ensuring it moves below the heat-insulating baffle to prevent obstruction of the mold shell's descent. The movable heat-insulating baffle can be programmed with a movement trajectory based on the blade size and shape, strictly controlling the gap between the upper and lower temperature zones. This invention enables effective control of impurities on the rim plate of single-crystal blades, resulting in blades with a complete single crystal structure from the blade body to the rim plate. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1A schematic diagram of the structure at the blade-shaped shell edge plate prepared by the traditional coating and sand-spraying process;

[0013] Figure 2 A schematic diagram of the structure of the blade-shaped shell edge plate prepared by the photopolymer ceramic printing process in this invention. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0016] 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 invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0017] See Figure 2 A method for controlling heterogeneous crystals in a single-crystal blade includes the following steps:

[0018] Step 1: Arrange the adjustable heat insulation baffle in the cold zone below the heat insulation carbon felt of the directional solidification furnace, so that the leading edge of the adjustable heat insulation baffle is close to the blade body of the blade shell. The thickness of the adjustable heat insulation baffle is less than that of the heat insulation carbon felt (heat insulation hard felt). Its function is to supplement the heat insulation module and to regulate the temperature field.

[0019] Step 2: Connect the control module to the adjustable heat insulation baffle. The control module includes a drive unit controlled by a preset program. The control module controls the motor through the preset program. The motor is located in the lower temperature zone of the furnace, that is, the cold zone. The vacuum motor with heat resistance is used to control the position of the heat insulation baffle. As for the specific structure of the control module, it is a conventional existing structure and will not be described in detail here.

[0020] Step 3: During the directional solidification of the blade shell, when the blade shell's edge plate enters the transition area between the insulating carbon felt and the adjustable insulating baffle, the control module drives the adjustable insulating baffle to move below the edge plate to insulate the edge plate and prevent premature cooling of the edge plate tip. Step 4: During the shell's descent, the control module controls the adjustable insulating baffle to extend and retract, allowing it to enter below the insulating carbon felt to prevent obstruction of the shell's descent. When the blade shell continues to descend until the edge plate is completely in the cold zone, the control module drives the adjustable insulating baffle to reset.

[0021] This invention employs an adjustable heat-insulating module single-crystal preparation technology, abandoning the method of controlling impurities with crystal guides, thus avoiding the risks of small-angle grain boundaries and recrystallization. A high-temperature resistant vacuum motor controls the adjustable heat-insulating module to achieve heat insulation in this region. Before the rim plate enters the transition zone between the upper and lower temperature zones, it is placed below the rim plate for heat preservation, preventing premature cooling of the rim plate tip. During the mold shell descent stage, the control motor controls the extension and retraction of the adjustable heat-insulating baffle, ensuring it moves below the heat-insulating baffle to prevent obstruction of the mold shell's descent. The movable heat-insulating baffle can be programmed with a movement trajectory based on the blade size and shape, strictly controlling the gap between the upper and lower temperature zones. This invention enables effective control of impurities on the rim plate of single-crystal blades, resulting in blades with a complete single crystal structure from the blade body to the rim plate.

[0022] See Figure 2 Understandably, in practical design, the insulating carbon felt divides the furnace cavity of the directional solidification furnace into hot and cold zones. Above the insulating carbon felt is a conformal flexible insulation plate, with a cavity in the center matching the axial projection shape of the single-crystal blade. By using the conformal flexible insulation plate, the gap between the mold shell and the insulating carbon felt can be minimized, blocking heat radiation between the upper and lower temperature zones. The conformal flexible insulation plate can be made of graphite paper.

[0023] See Figure 2 Specifically, multiple adjustable heat insulation baffles are evenly arranged side by side around the blade, and each adjustable heat insulation baffle is moved by a motor.

[0024] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above description is illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method of single crystal blade inhomogeneity control, characterized by, Includes the following steps: Step 1: Arrange the adjustable heat-insulating baffle in the cold zone below the heat-insulating carbon felt of the directional solidification furnace, so that the leading edge of the adjustable heat-insulating baffle is close to the blade body of the blade shell. Step 2: Connect the control module to the adjustable heat-insulating baffle. The control module includes a drive unit controlled by a preset program. Step 3: During the directional solidification of the blade shell, when the edge plate of the blade shell enters the transition area between the heat-insulating carbon felt and the adjustable heat-insulating baffle, the control module drives the adjustable heat-insulating baffle to move below the edge plate, providing heat insulation and preventing premature cooling of the edge plate tip. Step 4: During the shell descent phase, the control module controls the extension and retraction of the adjustable heat-insulating baffle, allowing it to enter below the heat-insulating carbon felt to prevent obstruction of the shell's descent. When the blade shell continues to descend until the edge plate is completely in the cold zone, the control module drives the adjustable heat-insulating baffle to reset.

2. The method for controlling heterogeneous crystals in single-crystal blades according to claim 1, characterized in that: The heat-insulating carbon felt divides the furnace cavity of the directional solidification furnace into a hot zone and a cold zone, and a conformal flexible heat-insulating plate is also provided above the heat-insulating carbon felt.

3. The method for controlling heterogeneous crystals in single-crystal blades according to claim 2, characterized in that: The conformal flexible insulation board is made of graphite paper.

4. The method for controlling heterogeneous crystals in single-crystal blades according to claim 1, characterized in that: Multiple adjustable heat insulation baffles are evenly arranged side by side around the blade portion.

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