Turbine blade air film hole precision forming method

[0028] Example 1

[0029] The precision forming method for the air film hole of the turbine blade includes the following steps:

[0030] 1) Manufacturing turbine blade resin mold

[0031] The present invention uses light curing rapid prototyping technology to manufacture resin molds. First, commercial three-dimensional software is used to design a resin mold CAD model, and a two-dimensional slice file with a layered thickness of 0.07 mm will be generated. The resin mold is quickly and automatically manufactured under the control of the slice file. Light curing prototype, see figure 1 , Where 1 is the leaf body and 2 is the air film pore structure. The manufactured turbine blade resin mold has high precision, high rigidity and good surface quality, and can be used as a ceramic ligand molding mold.

[0032] 2) Prepare ceramic slurry

[0033] First, dissolve the organic matter in deionized water, add dispersant and uniformly mixed alumina ceramic powder and mineralizer powder in sequence to make ceramic slurry, add initiator and catalyst before pouring, mix well and vacuum to remove ceramic slurry Bubbles, the viscosity is less than 1Pa·S; the ceramic slurry is poured into figure 1 Shown in the hollow turbine blade prototype resin mold cavity, and figure 1 The pores of the air film are filled.

[0034] Among them, the ceramic powder uses alumina powder with a particle size of 2 μm, 5 μm or 40 μm; the added mineralizer is zirconia, and the zirconia powder accounts for 5% of the mass of the ceramic powder.

[0035] 3) Freeze drying and high temperature sintering

[0036] After the ceramic slurry is solidified and formed in situ, remove the ceramic slurry pouring system and the peripheral structure of the resin mold, transfer the ceramic body into a vacuum drying oven, control the vacuum degree between 1pa and 10pa, and dry time according to the size of the body. The blade ceramic mold drying time is 48-72 hours, and the green body is taken out after drying. The temperature-raising process is controlled to burn out the resin mold and organic gel, and the ceramic particles are sintered under high temperature conditions to obtain figure 2 The complete ceramic mold shown in, where 3 is a monolithic ceramic mold, and 4 is a gas film hole core. In the present invention, through high-temperature sintering, under the action of the mineralizer, the room temperature flexural strength of the ceramic mold is higher than 70MPa, and the 1500°C high-temperature flexural strength is 15-25MPa.

[0037] 4) Directional solidification and core removal

[0038] After obtaining a ceramic mold that meets the requirements of directional solidification, it is placed in a three-chamber vacuum directional solidification furnace for directional solidification casting of hollow turbine blades. The ceramic mold is preheated to about 1500°C, kept for 30-60 minutes, and high-temperature metal is poured. After the blade is cooled, the ceramic mold on the surface of the blade is directly removed, and the ceramic core remaining inside the blade is removed by strong alkali corrosion. The selected core removal liquid is KOH with a concentration of 50 to 70 wt.%. The core removal process does not affect the gas. The surface quality and accuracy of the membrane holes can achieve such image 3 The turbine blade shown in is completely formed, where 5 is a complete turbine blade, and 6 is a formed air film hole.

[0039] In summary, the method for precise forming of gas film holes of turbine blades disclosed in the present invention combines light curing molding and gel injection molding technology to realize the casting of a ceramic core containing gas film holes. Including: 1) Use light curing rapid prototyping technology to manufacture turbine blade resin mold; 2) Use gel injection molding method to pour ceramic slurry into the resin mold prototype of turbine blade to obtain the casting blank, and realize the formation of air film hole ceramic core 3) Vacuum freeze-drying and high-temperature sintering further strengthen the gas film pore ceramic cores, and realize the formation of different ceramic-based gas film pore ceramic cores; 4) For different types of ceramic-based gas film pore ceramic cores, combined with directional solidification technology, it can be Realize the casting and molding of air film holes of a variety of high-temperature alloys, and finally remove the ceramic core remaining in the metal blades and air film holes through the core removal process to achieve high-quality molding of the cast air film holes.

[0040] According to the method of the present invention, according to the optimization of material design, the formed ceramic mold materials are rich in types, including alumina-based, silica-based, calcium-oxide-based and yttrium-oxide-based, and can be poured into a variety of alloy materials, such as iron-based high-temperature alloys, Nickel-based superalloys, cobalt-based superalloys, titanium aluminum alloys, etc., are formed into turbine blades with round holes, wedge-shaped and heterogeneous air film holes. The air film hole is formed by one-time casting and no secondary processing is required. The present invention has reasonable design and simple operation, can eliminate positioning errors, reduce defects such as remelted layers and micro-cracks, and omit the required equipment and man-hours for mold processing and punching, thereby achieving High-precision, high-performance and high-efficiency forming of reburning turbine blades with fine film holes. The present invention is expected to lift the limitation of the traditional perforating method on the development of high-efficiency film holes, promote the development of new film cooling theory and application research, provide new options for the formation of reburning turbine blades with complex cooling channels, and promote new high-efficiency heavy-duty The development of gas turbines.