Manufacturing method of single crystal superalloy guide vane wax pattern

Abstract

The present invention relates to the technical field of investment precision casting of single crystal blades of superalloys, and specifically relates to a method for manufacturing a wax pattern of a single crystal superalloy guide vane. During the process of manufacturing the free end of the blade wax part, the core of the guide vane is fixed at both ends. The large-end extension section and the small-end extension section of the core serve as the fixed end faces in the XYZ directions to ensure the positioning of the core in the XYZ directions. Wax is brushed on the side faces at both ends of the core extension section, and paint is brushed on the large-end extension section of the core. The small-end extension section of the core directly contacts the mold shell, so that the small-end extension section of the core is completely fixed. The exhaust edge extension section serves as the free end. At the free end of the exhaust edge extension section, positioning points are left at symmetrical positions on the blade basin and the blade back and painted evenly. Wax is brushed evenly on the positions outside the positioning points on the exhaust edge extension section. The present invention is mainly applicable to the manufacture of the free end of a guide vane with a relatively large inner cavity size, a relatively thick core size corresponding to the blade body, and a relatively large difference in the core size thickness between the blade body position and the exhaust edge position.

Description

Technical Field

[0001] The present invention relates to the technical field of investment precision casting of single crystal blades of superalloys, and specifically to a method for manufacturing a wax pattern of a single crystal superalloy guide vane. Background Art

[0002] With the continuous increase in the requirements for thrust and operating temperature of advanced aero-engines, the key high-temperature hot-end component, the turbine blade, needs to withstand the interaction of thermal stress and centrifugal force under more severe conditions for a long time. Nickel-based superalloys are still the preferred materials for the blades. However, the temperature-bearing capacity of single crystal alloys does not exceed 1150 °C, while the gas temperature at the turbine inlet can reach above 1500 °C. In addition to coating the blade surface, an internal cavity cooling structure is also an effective method. Therefore, single crystal blades with complex internal cavity structures have become a symbol of advanced aero-engines. However, this has also increased the casting process difficulty, especially the casting problem of large hollow turbine guide vanes.

[0003] During the casting production process of large hollow turbine guide vanes (the outer dimension range is: guide vane height: 20 mm to 200 mm, blade width: 50 mm to 120 mm, and the cavity dimension range is: length: 30 mm to 120 mm, width: 10 mm to 30 mm), due to factors such as the large size of the ceramic core, the relatively thick blade body and the large thickness difference between the blade body and the exhaust edge, and the inconsistent expansion coefficients of the ceramic core and the mold shell, the final mold shell will crack and be scrapped. To solve this problem, a more reasonable free end setting method needs to be adopted to ensure that the core has sufficient collapsibility during the mold shell preparation process, thereby realizing the formation of the mold shell. Therefore, the free end setting method is crucial for the preparation of the mold shell of large hollow turbine guide vanes and directly affects the final qualification rate of the blades. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for manufacturing a wax pattern of a single crystal superalloy guide vane, which is mainly applicable to the production of the free end of guide vanes with relatively large internal cavity dimensions, relatively thick core dimensions corresponding to the blade body, and relatively large thickness differences in the core dimensions between the blade body position and the exhaust edge position. At the same time, it is also applicable to the production of the free end of single crystal hollow blades with ordinary structures.

[0005] The technical solution of the present invention is as follows:

[0006] A method for manufacturing a single-crystal superalloy guide vane wax mold. During the process of manufacturing the free end of the blade wax part, the core of the guide vane is fixed at both ends. The extended section of the large end face of the core and the extended section of the small end face of the core are used as the fixed end faces in the XYZ directions to ensure the positioning of the core in the XYZ directions. Wax is brushed on the side faces at both ends of the extended section of the core, and paint is brushed on the extended section of the large end face of the core. The extended section of the small end face of the core is directly in contact with the mold shell to completely fix the extended section of the small end face of the core. The extended section of the exhaust edge is made as the free end. At the free end of the extended section of the exhaust edge, positioning points are left at symmetrical positions on the blade basin and the blade back and painted evenly. Wax is evenly brushed on the positions outside the positioning points on the extended section of the exhaust edge.

[0007] In the method for manufacturing the single-crystal superalloy guide vane wax mold described above, the core is fixed at both ends, that is: the extended section of the large end face of the core and the extended section of the small end face of the core at the blade body position are used as the fixed ends.

[0008] In the method for manufacturing the single-crystal superalloy guide vane wax mold described above, wax is brushed on the side faces at both ends of the extended section of the core, that is: wax is brushed on the side face of the extended section of the large end face of the core and the side face of the extended section of the small end face of the core.

[0009] In the method for manufacturing the single-crystal superalloy guide vane wax mold described above, the length of the extended section of the large end face of the core at the blade body position of the guide vane is 5 - 20 mm, the height dimension of the extended section of the large end face of the core is 20 - 80 mm, and the width of the extended section of the large end face of the core is 10 - 30 mm; the length of the extended section of the small end face of the core at the blade body position is 5 - 20 mm, the height dimension of the extended section of the small end face of the core is 20 - 60 mm, and the width of the extended section of the small end face of the core is 10 - 30 mm.

[0010] In the method for manufacturing the single-crystal superalloy guide vane wax mold described above, the wax brushing thickness on the side faces of the extended sections of the large end face of the core and the extended section of the small end face of the core located on both sides should be 1 - 2 mm, and the paint brushing thickness around the extended section of the large end face of the core is 0.02 - 0.1 mm.

[0011] In the method for manufacturing the single-crystal superalloy guide vane wax mold described above, the width of the free end of the extended section of the exhaust edge is 1.5 - 20 mm, the diameter of the positioning point on the extended section of the exhaust edge is 1 - 15 mm, and the spacing between the positioning points on the extended section of the exhaust edge is 5 - 90 mm.

[0012] In the method for manufacturing the single-crystal superalloy guide vane wax mold described above, the positioning points of the extended section of the exhaust edge are symmetrically distributed on both sides of the blade basin and the blade back of the core. The paint brushing thickness at the positions of the positioning points of the extended section of the exhaust edge is evenly 0.02 - 0.1 mm, and the wax brushing thickness on the extended section of the exhaust edge outside the positioning points of the extended section of the exhaust edge is evenly 1 - 2 mm.

[0013] The design concept of the present invention is:

[0014] During the production process of the wax mold, the core of the large-sized turbine guide vane is fixed at both ends to ensure the positioning of the core in the XYZ directions, thereby guaranteeing the stability of the wall thickness dimension of the vane. Wax is brushed on the side surfaces at both ends of the core extension section, and paint is brushed on the large end extension section of the core to create a gap between the core and the shell mold, reduce the positioning area, and prevent shell mold cracks caused by the shrinkage rate between the shell mold and the core. The small end extension section of the core directly contacts the shell mold, completely fixing the small end extension section of the core and ensuring the stable position of the core in the shell mold without deviation. Positioning points are left and evenly painted at the symmetric positions of the blade basin and the blade back at the free end of the exhaust edge extension section, and wax is evenly brushed on the positions other than the positioning points on the exhaust edge extension section to ensure a certain movement gap for the core in the shell mold, so that it will not be stressed and fractured due to the expansion difference during the high-temperature expansion process, and ensure that there is no core breakage or leakage.

[0015] The present invention has the following advantages and beneficial effects:

[0016] 1. The present invention is easy to operate, and the rate of core breakage and leakage of the vane is low.

[0017] 2. By manufacturing the free end of the guide vane, the present invention ensures the control of the wall thickness dimension of the vane, reduces the phenomenon of shell mold cracks caused by the difference in expansion coefficients between the core and the shell mold, and increases the qualified rate of shell mold preparation.

[0018] 3. The large single-crystal guide vane has a cavity structure and a relatively large core size. The method of the present invention has the characteristics of stable positioning structure and high qualified rate of shell mold preparation for the vane. Especially for the single-crystal turbine guide vane with a large internal cavity structure, it can greatly improve the qualified rate of the large single-crystal guide vane and the integrity of the casting. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the free end setting of the single-crystal turbine guide vane of the present invention.

[0020] In the figure: 1 large end extension section of the core, 2 side surface of the large end extension section of the core, 3 small end extension section of the core, 4 side surface of the small end extension section of the core, 5 exhaust edge extension section, 6 positioning point of the exhaust edge extension section, 7 blade body.

[0021] Figure 2 It is a CT detection result diagram of the shell mold of the single-crystal turbine guide vane of the present invention. Detailed Embodiment

[0022] During the specific implementation process, such as Figure 1As shown in the figure, the method for manufacturing the free end of a large single-crystal turbine guide vane is as follows: During the process of manufacturing the free end of the vane wax pattern, a two-end fixation method is adopted, that is, the large-end extension section 1 and the small-end extension section 3 of the core at the blade body 7 position are used as the fixed ends. Wax is brushed on the side 2 of the large-end extension section of the core and the side 4 of the small-end extension section of the core, and paint is brushed around the large-end extension section 1 of the core at the blade body 7 position. The large-end extension section 1 and the small-end extension section 3 of the core are used as the fixed end faces in the XYZ directions. The exhaust-edge extension section 5 is the free end, and an exhaust-edge extension section positioning point 6 is set at the exhaust-edge extension section 5. The positioning methods for the blade concave and convex sides of the core are the same, and the positioning point positions are completely symmetrical. Among them, the difference between the large end face and the small end face is that the cross-sectional area of the large-end core is relatively larger than that of the small-end core. The difference between brushing wax and brushing paint is that the thickness of the paint is much smaller than that of the wax. Wax is brushed on the side faces at both ends of the core, and paint is brushed on the large-end extension section of the core, ensuring that the large-end face of the core has sufficient expansion space, and the offset in the XYZ directions is less than the core offset tolerance, and the core will not cause shell cracks due to core expansion during the baking process.

[0023] The length of the large-end extension section 1 of the core at the blade body 7 position of the large single-crystal turbine guide vane is 5 - 20 mm, the height dimension of the large-end extension section of the core is 20 - 80 mm, and the width of the large-end extension section of the core is 10 - 30 mm; the length of the small-end extension section 3 of the core at the blade body 7 position is 5 - 20 mm, the height dimension of the small-end extension section of the core is 20 - 60 mm, and the width of the small-end extension section of the core is 10 - 30 mm; the wax brushing thickness on the side 2 of the large-end extension section of the core and the side 4 of the small-end extension section of the core located on both sides should be 1 - 2 mm, and the paint brushing thickness around the large-end extension section 1 of the core is 0.02 - 0.1 mm. The width of the free end of the exhaust-edge extension section 5 of the single-crystal turbine blade is 1.5 - 20 mm, the diameter of the exhaust-edge extension section positioning point 6 is 1 - 15 mm, the spacing of the exhaust-edge extension section positioning points 6 is 5 - 90 mm, the exhaust-edge extension section positioning points 6 are symmetrically distributed on both sides of the blade concave and convex sides of the core, and the paint brushing thickness evenly on the positions of the exhaust-edge extension section positioning points 6 is 0.02 - 0.1 mm, and the wax brushing thickness evenly on the exhaust-edge extension section 5 outside the exhaust-edge extension section positioning points 6 is 1 - 2 mm.

[0024] Next, the present invention will be further described in detail through embodiments.

[0025] Embodiment 1

[0026] As Figure 1As shown in the figure, this embodiment designs a method for manufacturing the free end of a single-crystal turbine guide vane. During the process of manufacturing the free end of the wax part, the core extension section at the blade position is used as the fixed end (fixed at both ends by the large-end extension section and the small-end extension section of the core), wax is brushed on both side surfaces of the core extension section, positioning points are left at symmetrical positions of the blade basin and blade back on the large-end extension section of the core, and paint is evenly brushed at the positions of the positioning points on the exhaust-edge extension section (in this embodiment, the specific brand of the paint refers to an aqueous solution of methyl blue with a concentration of 1 wt%). Wax is evenly brushed at the position of the exhaust-edge extension section except for the positioning points on the exhaust-edge extension section. The exhaust-edge extension section is made into the free end, and the positioning methods for the blade basin and blade back of the core are the same, and the positions of the positioning points are completely symmetrical. There is no exhaust channel on the exhaust edge, and it is a closed channel.

[0027] The length of the large-end extension section of the core at the blade position of the single-crystal turbine guide vane is 15 mm, the height dimension of the large-end extension section of the core is 75 mm, and the width of the large-end extension section of the core is 27 mm; the length of the small-end extension section of the core at the blade position is 10 mm, the height dimension of the small-end extension section of the core is 55 mm, and the width of the small-end extension section of the core is 25 mm; the wax-brushing thickness on both side surfaces of the core extension section is 1 mm, and the paint-brushing thickness evenly around the large-end extension section of the core at the blade position is 0.02 mm. The width of the free end of the exhaust-edge extension section of the single-crystal turbine blade is 5 mm, 3 positioning points are left on each of the blade basin and blade back of the exhaust edge, the diameter of the positioning points on the exhaust-edge extension section is 2 mm, the spacing between the positioning points on the exhaust-edge extension section is 50 mm, the positioning points on the exhaust-edge extension section are symmetrically distributed on both sides of the blade basin and blade back of the core, the paint-brushing thickness evenly at the positions of the positioning points on the exhaust-edge extension section is 0.05 mm, and the wax-brushing thickness evenly at the exhaust-edge extension section except for the positioning points on the exhaust-edge extension section is 1 mm.

[0028] As Figure 2 shown, the wax parts after manufacturing the free end are combined for shell making and baking. The industrial CT inspection results show that the qualified rate of the shell reaches 90%. After casting the shell, the core inclusion rate reaches 95%, and the qualified rate of the wall thickness dimension reaches 90%.

[0029] Embodiment 2

[0030] As Figure 1As shown in the figure, this embodiment designs a method for manufacturing the free end of a single-crystal turbine guide vane. During the process of manufacturing the free end of the wax part, the core extension section at the airfoil position is used as the fixed end (fixed at both ends by the large-end extension section and the small-end extension section of the core), wax is brushed on both side surfaces of the core extension section, positioning points are left at the symmetrical positions of the blade concave and convex surfaces on the large-end extension section of the core at the airfoil position, and paint is evenly brushed at the positions of the positioning points on the extension section of the exhaust edge (in this embodiment, the specific brand of the paint refers to an aqueous solution of methyl blue with a concentration of 1 wt%). Wax is evenly brushed at the position of the exhaust edge extension section except for the positioning points on the exhaust edge extension section. The extension section of the exhaust edge is used as the free end, and the positioning methods for the concave and convex surfaces of the core are the same, and the positions of the positioning points are completely symmetrical. There is no exhaust channel at the exhaust edge, which is a closed channel.

[0031] The length of the large-end extension section of the core at the airfoil position of the single-crystal turbine guide vane is 10 mm, the height dimension of the large-end extension section of the core is 50 mm, and the width of the large-end extension section of the core is 15 mm; the length of the small-end extension section of the core at the airfoil position is 8 mm, the height dimension of the small-end extension section of the core is 35 mm, and the width of the small-end extension section of the core is 10 mm; the thickness of the wax brushed on both side surfaces of the core extension section is 1 mm, and the thickness of the paint evenly brushed around the large-end extension section of the core at the airfoil position is 0.02 mm. The width of the free end of the extension section of the exhaust edge of the single-crystal turbine vane is 5 mm, 2 positioning points are left on each of the concave and convex surfaces of the exhaust edge, the diameter of the positioning points is 2 mm, the spacing between the positioning points on the extension section of the exhaust edge is 15 mm, the positioning points on the extension section of the exhaust edge are symmetrically distributed on both sides of the concave and convex surfaces of the core, the thickness of the paint evenly brushed at the positions of the positioning points on the extension section of the exhaust edge is 0.05 mm, and the thickness of the wax evenly brushed at the position of the exhaust edge extension section except for the positioning points on the exhaust edge extension section is 1 mm.

[0032] As Figure 2 shown in the figure, the wax part after manufacturing the free end is combined to make a shell and baked. The industrial CT detection results show that the qualified rate of the shell reaches 95%. After casting the shell, the core encapsulation rate reaches 93%, and the qualified rate of the wall thickness dimension reaches 90%.

[0033] The results of the embodiment show that the present invention is mainly applicable to the method for manufacturing the free end of a single-crystal turbine guide vane with large dimensions and large inner cavity core dimensions, and is also applicable to the method for manufacturing the free end of a common single-crystal turbine guide vane, that is, it is applicable to blades with exhaust channels at the exhaust edge and blades without exhaust channels at the exhaust edge. The present invention can effectively improve the qualified rate of the preparation of the shell of a large single-crystal guide vane, ensure the core encapsulation rate and the wall thickness dimension deviation of the guide vane, and thus improve the qualified rate of the casting.

Claims

1. A method for manufacturing a single crystal superalloy guide vane wax pattern, characterized in that, During the process of manufacturing the free end of the blade wax part, the core of the guide vane is fixed at both ends. The extended section of the large end face of the core and the extended section of the small end face of the core serve as the fixed end faces in the XYZ directions to ensure the positioning of the core in the XYZ directions. Wax is brushed on the two side faces at both ends of the core extension section, and paint is brushed on the extended section of the large end face of the core. The extended section of the small end face of the core directly contacts the mold shell, making the extended section of the small end face of the core completely fixed. The extended section of the exhaust edge is made into a free end. At the free end of the extended section of the exhaust edge, positioning points are left at symmetric positions on the blade pressure surface and the blade suction surface and painted evenly. Wax is evenly brushed on the positions outside the positioning points on the extended section of the exhaust edge. The core is fixed at both ends, that is: the extended section of the large end face of the core and the extended section of the small end face of the core at the blade body position serve as the fixed ends. Wax is brushed on the two side faces at both ends of the core extension section, that is: wax is brushed on the side face of the extended section of the large end face of the core and the side face of the extended section of the small end face of the core.

2. The manufacturing method of the single crystal superalloy guide vane wax pattern according to claim 1, wherein, The length of the extended section of the large end face of the core at the blade body position of the guide vane is 5 - 20 mm, the height dimension of the extended section of the large end face of the core is 20 - 80 mm, and the width of the extended section of the large end face of the core is 10 - 30 mm; the length of the extended section of the small end face of the core at the blade body position is 5 - 20 mm, the height dimension of the extended section of the small end face of the core is 20 - 60 mm, and the width of the extended section of the small end face of the core is 10 - 30 mm.

3. The manufacturing method of the single crystal superalloy guide vane wax pattern according to claim 1, characterized in that, The thickness of the wax brushed on the side faces of the extended sections of the large end face of the core and the extended sections of the small end face of the core located on both sides should be 1 - 2 mm, and the thickness of the paint brushed around the extended section of the large end face of the core is 0.02 - 0.1 mm.

4. The manufacturing method of the single crystal superalloy guide vane wax pattern according to claim 1, characterized in that, The width of the free end of the extended section of the exhaust edge is 1.5 - 20 mm, the diameter of the positioning point on the extended section of the exhaust edge is 1 - 15 mm, and the spacing between the positioning points on the extended section of the exhaust edge is 5 - 90 mm.

5. The manufacturing method of the single crystal superalloy guide vane wax pattern according to claim 1, characterized in that, The positioning points of the extended section of the exhaust edge are symmetrically distributed on both sides of the blade pressure surface and the blade suction surface of the core. The thickness of the paint evenly brushed on the positions of the positioning points of the extended section of the exhaust edge is 0.02 - 0.1 mm, and the thickness of the wax evenly brushed on the extended section of the exhaust edge outside the positioning points of the extended section of the exhaust edge is 1 - 2 mm.

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