A rapid prototyping method for multi-material integrated casting of a hollow turbine blade

Abstract

The application discloses a kind of rapid prototyping methods of multi-material integration casting of hollow turbine blade, comprising: step (1), according to blade structure, custom blade casting shape and establish three-dimensional model;Step (2), respectively configure core ceramic slurry and shell ceramic slurry;Step (3), the core ceramic slurry and shell ceramic slurry of different materials are respectively injected into the resin pool and direct writing device of printer;Step (4), by direct writing light solidification synchronous forming, obtain multi-material integrated blade blank;Step (5), the blank is freeze-dried, after debinding sintering, obtain integrated casting mold.The casting shell of the present application is directly formed by ceramic slurry with good structural stability, the core is formed by light solidification by ceramic slurry with strong chemical stability and easy to dissolve, which ensures the casting precision and greatly reduces the difficulty of core removal.Solve the problem that traditional single material ceramic casting cannot consider performance and multi-material ceramic casting manufacturing difficulty.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing, specifically a rapid prototyping method for a multi-material integrated casting mold of hollow turbine blades. Background Technology

[0002] Hollow turbine blades in aero-engines and industrial gas turbines are key components in modern industry. They are typically located at the hot end of the mechanical structure, enduring the scouring of high-temperature exhaust gases and temperature fluctuations during start-up and shutdown, operating in harsh and extreme environments with high pressure and temperature. During the casting of hollow turbine blades, the ceramic shell needs to withstand certain thermal and mechanical shocks, and the ceramic core needs to be immersed in high-temperature molten metal for an extended period. Furthermore, a significant temperature gradient exists along the height of the core during solidification. This necessitates sufficient strength, excellent creep resistance, chemical stability, and appropriate chemical reactivity for subsequent core removal. These issues have become technical bottlenecks in turbine blade manufacturing and even the precision casting industry.

[0003] Existing casting methods mostly use single-material cores and shells, resulting in long processing times, high costs, and an inability to adjust materials to meet different core and shell requirements. Furthermore, with the development of advanced cooling technology, the internal structure of hollow blades is becoming increasingly complex, and the preparation and removal of cores in traditional casting methods severely restricts the development of hollow turbine blades. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a rapid prototyping method for a multi-material integrated mold for hollow turbine blades. The method uses a composite rapid prototyping approach to directly manufacture the integrated mold, ensuring the strength of the shell without affecting the removal of the core, and is easy to design and process.

[0005] This invention is achieved through the following technical solution:

[0006] A rapid prototyping method for a multi-material integrated casting mold of hollow turbine blades includes the following steps:

[0007] Step (1): Based on the blade structure, customize the blade casting shape and establish a three-dimensional model;

[0008] Step (2): Prepare the core ceramic slurry and the shell ceramic slurry respectively;

[0009] Step (3): Inject the core ceramic paste and shell ceramic paste of different materials into the resin pool and direct writing device of the printer, respectively;

[0010] Step (4): Obtain a multi-material integrated blade blank by direct writing photopolymerization synchronous molding;

[0011] Step (5): Freeze-dry the billet, degrease and sinter it to obtain an integrated casting mold.

[0012] A further improvement of the present invention is that the three-dimensional model of the blade casting mold in step (1) includes two parts: the core and the shell. The shell is formed by direct writing, and the core is formed by photopolymerization.

[0013] A further improvement of the present invention is that the core ceramic slurry in step (2) is a silica slurry with a photocurable resin.

[0014] A further improvement of the present invention is that the shell ceramic slurry in step (2) is an alumina or silicon carbide slurry with shear-thinning properties, which is suitable for direct writing.

[0015] A further improvement of the present invention is that, in step (4), the direct writing photopolymerization synchronous molding is performed by first performing photopolymerization mode printing and then performing direct writing mode printing when printing on the same plane.

[0016] A further improvement of the present invention is that, in step (4), a three-dimensional model of the mold is established according to the shape of the blade and converted into an STL file, and the three-dimensional model is layered and the printing path is planned using Simplify3D software.

[0017] A further improvement of the present invention is that, in step (4), in the photocuring mode, the working platform is lowered until the liquid surface in the resin tank is submerged to the specified layer thickness, the laser is started, and the ceramic core is formed by using the laser beam.

[0018] A further improvement of the present invention is that, in step (4), in the direct writing mode, ceramic slurry is extruded from the direct writing molding printhead using a screw extrusion to form a ceramic shell portion.

[0019] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0020] This invention provides a rapid prototyping method for a multi-material integrated casting mold of hollow turbine blades. It employs a composite additive manufacturing device, combining the advantages of direct-write molding and stereolithography. The easily soluble ceramic slurry for the core and the high-hardness ceramic slurry for the shell are simultaneously formed using both stereolithography and direct-write methods, ultimately yielding a multi-material integrated blade casting mold. This simplifies the molding steps of multi-material castings and solves the problem of traditional single-material blade castings failing to balance strength and core removal.

[0021] In summary, this invention achieves optimal casting performance by using direct-write photopolymerization integral molding, direct-write molding of silicon carbide / alumina paste to form the shell, and photopolymerization of silicon oxide paste to form the core, with different additive manufacturing methods used in different areas. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the integrated molding equipment used in this invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Laser emitter, 2. Cast mold shell, 3. Resin tank, 4. Working platform, 5. Cast mold core, 6. Direct writing molding device, 7. Direct writing-photocuring integrated platform. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings. These descriptions are intended to explain the invention and not to limit it.

[0026] A rapid prototyping method for a multi-material integrated casting mold of hollow turbine blades includes the following steps:

[0027] Step 1: Prepare the ceramic core photocurable slurry;

[0028] Silica powder particles with particle sizes of 100μm, 40μm, 5μm and 2μm were ball-milled and mixed for gradation. After gradation, appropriate amounts of corundum powder and zircon powder were added to the ceramic powder as mineralizers and ball-milled for 1 hour for later use.

[0029] Photosensitive resins were prepared using PUA (polyurethane acrylate) as oligomers, HDDA (16-hexanediol diacrylate) and TMPTA (trimethylolpropane triacrylate) as reactive diluents, and TPO (2,4,6-trimethylbenzoyl diphenoxyphosphine) as photoinitiators.

[0030] The prepared photosensitive resin and powder were mixed at a ratio of 60% solid content and homogenized in a homogenizer at speeds of 800 r / min, 1400 r / min and 1200 r / min for 5 hours to obtain a ceramic slurry for core photocuring.

[0031] Step 2: Prepare ceramic shell direct writing slurry;

[0032] Alumina or silicon carbide powder particles with particle sizes of 100μm, 40μm, 5μm, and 2μm were ball-milled and mixed to obtain ceramic particle powder with a graded distribution.

[0033] PEI (polyethyleneimine) and PAA (polyacrylic acid) were dissolved in deionized water at a mass ratio of 200:1. An appropriate amount of GG (guar gum) was added as a binder. The mixture was ultrasonically vibrated for 15 minutes to mix evenly. Then, alumina or silicon carbide powder with the desired gradation was added. The mixture was homogenized in a homogenizer at a speed of 1200 r / min for 15 minutes to obtain a ceramic slurry for direct writing molding of shells.

[0034] Step 3: Filling the slurry and preparing for printing;

[0035] As shown in the figure, the integrated molding equipment used in this invention includes a laser emitter 1, a casting shell 2, a resin pool 3, a working platform 4, a casting core 5, a direct writing molding device 6, and a direct writing-photocuring integrated platform 7.

[0036] Inject the ceramic core photocurable slurry into the resin tank, ensuring the liquid level does not exceed 2 / 3 of the total depth of the resin tank. After vacuum homogenizing the ceramic shell direct writing slurry, slowly inject it into the barrel of the direct writing molding mechanism to avoid voids in the slurry within the barrel.

[0037] Based on the blade shape, a 3D model of the mold was created and converted into an STL file. Simplify3D software was used to layer the 3D model and plan the printing path.

[0038] Entering the photocuring mode, the work platform is lowered until the liquid level in the resin tank is submerged to the specified layer thickness. The laser is then activated to form the ceramic core using the laser beam.

[0039] After the photocuring step is completed, the substrate is lifted out of the resin tank, the direct writing-photocuring integrated platform moves and enters the direct writing mode. The ceramic paste is extruded from the direct writing molding printhead using a screw extrusion to form the ceramic shell part.

[0040] Repeat the photopolymerization mode and the direct writing mode to complete the casting printing.

[0041] Step 4: Freeze-drying;

[0042] The ceramic mold was vacuum freeze-dried for 80 hours to remove moisture from the shell and core. Then, it was degreased by holding it at 262, 365, and 505℃ for 1 hour each in a vacuum sintering furnace, and then heated to 1200℃ and held for 6 hours to fully sinter the ceramic core.

[0043] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A rapid prototyping method for a multi-material integrated casting mold of hollow turbine blades, characterized in that, Includes the following steps: Step (1): Based on the blade structure, customize the blade casting shape and establish a three-dimensional model; Step (2): Prepare the core ceramic slurry and the shell ceramic slurry respectively; Step (3): Inject the core ceramic paste and shell ceramic paste of different materials into the resin pool and direct writing device of the printer, respectively; Step (4): Obtain a multi-material integrated blade blank by direct writing photopolymerization synchronous molding; Step (5): Freeze-dry the billet, degrease and sinter it to obtain an integrated casting mold.

2. The rapid prototyping method for a multi-material integrated casting mold of a hollow turbine blade according to claim 1, characterized in that, In step (1), a three-dimensional model of the blade casting mold is customized, which includes two parts: the core and the shell. The shell is formed by direct writing, and the core is formed by photopolymerization.

3. The rapid prototyping method for a multi-material integrated casting mold of a hollow turbine blade according to claim 1, characterized in that, In step (2), the core ceramic slurry is a silica slurry with a photocurable resin.

4. The rapid prototyping method for a multi-material integrated casting mold of a hollow turbine blade according to claim 1, characterized in that, In step (2), the medium-sized shell ceramic slurry is an alumina or silicon carbide slurry with shear-thinning properties, suitable for direct writing.

5. The rapid prototyping method for a multi-material integrated casting mold of a hollow turbine blade according to claim 1, characterized in that, In step (4), direct writing and photocuring are performed simultaneously. When printing on the same plane, photocuring mode printing is performed first, followed by direct writing mode printing.

6. The rapid prototyping method for a multi-material integrated casting mold of a hollow turbine blade according to claim 1, characterized in that, In step (4), a three-dimensional model of the mold is created based on the shape of the blade and converted into an STL file. The Simplify3D software is used to layer the three-dimensional model and plan the printing path.

7. The rapid prototyping method for a multi-material integrated casting mold of a hollow turbine blade according to claim 1, characterized in that, In step (4), in the photocuring mode, the working platform is lowered until the liquid level in the resin tank is submerged to the specified layer thickness, and the laser is started to form a ceramic core using the laser beam.

8. The rapid prototyping method for a multi-material integrated casting mold of a hollow turbine blade according to claim 1, characterized in that, In step (4), in direct writing mode, ceramic slurry is extruded from the direct writing molding printhead using a screw extrusion to form the ceramic shell part.

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