A wax mold structure for controlling the grains of a large-sized four-connected hollow single-crystal blade

Abstract

The present invention discloses a wax mold structure for controlling the grains of a large-sized four-connected hollow single crystal blade, comprising: a gating system, which includes a bottom plate, a middle column, at least one runner and a sprue cup; at least one four-connected hollow blade, the solidification direction V of the four-connected hollow blade is parallel to its center line L, the large flange of the four-connected hollow blade is located below and the air inlet side faces one side of the middle column, the small flange is located above and the end of the small flange is connected to the runner through a feeder piece, the large flange is connected to the bottom plate through a grain selector, and an arc-shaped inner wrapper is arranged between the four-connected hollow blade and the middle column; the present invention realizes the grain growth of the large-sized four-connected hollow single crystal blade into a complete single crystal, successfully prepares the large-sized four-connected hollow single crystal blade, filling the gap in this technical field at home and abroad; at the same time, the precise control of the size of the large-sized four-connected hollow single crystal blade is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of investment casting of blades, and particularly relates to a wax mold structure for controlling the grains of large-sized four-connected hollow single-crystal blades. Background Art

[0002] The single-crystal turbine blades made of superalloy are known as the pearl on the crown of industrial technology. The integral casting of multi-connected single-crystal guide vanes has become the mainstream development trend of aero-engine design because it effectively increases the airtightness and thermal shock resistance. The manufacturing of multi-connected single-crystal guide vanes is difficult, and currently, it is generally only applied in advanced aero-engines. The low-pressure first-stage single-crystal guide vanes of the GE9X engine of General Electric Company in the United States adopt a four-connected design, without an inner cavity structure, and are four-connected solid. The manufacturing of the blades is completed by PCC (Precision Castparts Corp) in the United States. Some models of engines in China adopt a two-connected or three-connected single-crystal design and have been successfully prepared. The large wide-body airliner C929 independently developed in China will be planned to be equipped with the independently developed aero-engine CJ2000, whose low-pressure first-stage single-crystal guide vanes adopt a four-connected design and are of a hollow structure, with the maximum span of the blades being 280 mm. However, the manufacturing of large-sized four-connected hollow single-crystal blades is blank both at home and abroad.

[0003] The technology of grain and size control is the key technology for the development of single-crystal blades. Due to the complex structure and large size of large-sized four-connected hollow blades, the heat dissipation between the blades affects each other, and the dendrite growth intersects and converges. During the directional solidification process, it is very easy to generate crystal defects such as stray grains and freckles, and the difficulty of controlling crystal defects is increased by several times compared with the previous two-connected and three-connected ones. The solidification mode has an important influence on the blade size. The previous two-connected and three-connected single-crystal blades generally adopt the diagonal as the solidification direction. Since the shrinkage rates of directional solidification in the X, Y, and Z directions are different, such a solidification direction (Z direction) is not consistent with the blade center line. The shrinkage law and structure of the blade during solidification are intricate, and the blade profile and flow passage surface are very easy to twist, and it is difficult to guarantee the size. Moreover, the four-connected single-crystal blades are larger in size and more complex in structure, and the precise control of the size is very difficult. Summary of the Invention

[0004] The main purpose of the present invention is to provide a wax mold structure for controlling the grains of large-sized four-connected hollow single-crystal blades, which can effectively solve the problems in the background art.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a wax mold structure for controlling the grains of large-sized four-connected hollow single-crystal blades, including:

[0006] A gating system, the gating system includes a bottom plate, a middle column, at least one runner, and a sprue cup. The upper and lower ends of the middle column are respectively connected to the middle part of the bottom plate and the sprue cup, and the sprue cup is connected to the runner;

[0007] At least one four-connected hollow blade, which includes a blade body, a large flange at both ends of the blade body, and a small flange. The solidification direction V of the four-connected hollow blade is parallel to its center line L. The large flange of the four-connected hollow blade is located below and the air inlet edge faces one side of the middle column. The small flange is located above, and the end of the small flange is connected to the runner through a riser piece;

[0008] At least one selector, the starting end of the selector is connected to the bottom plate, and the spiral end of the selector is connected to the large flange end of the four-connected hollow blade through a guiding wafer;

[0009] An arc-shaped inner enclosing plate, which is arranged between the four-connected hollow blade and the middle column.

[0010] Preferably, the riser piece includes a rectangular riser piece and a curved riser piece. Small sealing teeth are provided on the outer end face of the small flange. The small sealing teeth are connected to the rectangular riser piece and the rectangular riser piece is of the same width as the small sealing teeth. The two side edges of the small flange are connected to the rectangular riser piece through the curved riser piece.

[0011] Preferably, the curved riser piece is connected to the upper 1 / 3 of the rectangular riser piece.

[0012] Preferably, the guiding wafer includes two triangular guiding wafers and two curved guiding wafers. Two large sealing teeth are provided on the outer end face of the large flange. The large sealing teeth are respectively connected to the spiral end of the selector through the triangular guiding wafers. The two side edges of the large flange are connected to the corresponding triangular guiding wafers through the curved guiding wafers.

[0013] Preferably, the curved guiding wafer is connected to the upper 1 / 3 of the triangular guiding wafer.

[0014] Preferably, both the curved guiding wafer and the curved riser piece are provided with 10 - 30 mm hollowings with a size of 10 - 30 mm at intervals.

[0015] Preferably, a lower mold head for positioning the core is provided on the outer end face of the large flange. The ratio of the length of the lower mold head exposed to the width of the core is greater than 1:1. A positioning hole with a length and width less than 1 / 2 of the contour of the lower mold head is arranged at the middle position of the lower mold head.

[0016] Preferably, an upper mold head with a free end is provided on the outer end face of the small flange. A wax layer with a thickness of 0.3 - 0.6 mm is evenly coated on the surface of the upper mold head.

[0017] Preferably, the top surface of the arc-shaped inner enclosing plate is flush with the upper end of the four-connected hollow blade, and the minimum distance between the arc-shaped inner enclosing plate and the four-connected hollow blade is 10 - 30 mm.

[0018] Preferably, the runner includes an inclined section, an arc section, and a vertical section that are smoothly butted in sequence. The vertical section is connected to the feeding piece, and the axis line of the vertical section coincides with the center line L of the four-connected hollow blade.

[0019] Compared with the traditional technology, the beneficial effects of the present invention are as follows: By making the directional solidification direction of the four-connected hollow blade consistent with the direction of its center line, the present invention avoids the shrinkage deformation law of the four-connected hollow blade with complex structure in the solidification direction. By adopting the method of having the large flange at the bottom and the small flange at the top, the high temperature gradient at the initial stage of the drawing is fully utilized to ensure the single crystal growth of the large flange. And by adopting the method of having the air inlet edge facing inwards, the flange gradually increases from inside to outside, and the temperature field near the flange gradually increases from inside to outside, which can ensure the sequential solidification of the flange. The setting of the arc-shaped inner cladding plate further ensures the temperature gradient and the stability of the temperature field. The present invention realizes the grain growth of the large-size four-connected single-crystal hollow blade into a complete single crystal, successfully prepares the large-size four-connected single-crystal hollow blade, filling the gap in this technical field at home and abroad. At the same time, the precise control of the size of the large-size four-connected single-crystal hollow blade is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a three-dimensional schematic diagram of the overall structure of the present invention;

[0021] Figure 2 is a three-dimensional schematic diagram of a partial structure of the present invention;

[0022] Figure 3 is Figure 2 a schematic diagram of another perspective

[0023] Figure 4 is a top view of the overall structure of the present invention;

[0024] Figure 5 is a schematic diagram of the connection between the four-connected hollow blade and the gating system of the present invention;

[0025] Figure 6 is a schematic diagram of the core structure of the four-connected hollow blade of the present invention.

[0026] In the figure: 1. Gating system; 11. Bottom plate; 12. Middle column; 13. Runner; 131. Inclined section; 132. Arc section; 133. Vertical section; 14. Sprue cup; 2. Four-connected hollow blade; 21. Blade body; 22. Large flange; 221. Large sealing tooth; 23. Small flange; 231. Small sealing tooth; 3. Crystal selector; 4. Feeding piece; 41. Rectangular feeding piece; 42. Curved feeding piece; 5. Seed wafer; 51. Triangular seed wafer; 52. Curved seed wafer; 6. Arc-shaped inner cladding plate; 7. Lower mold head; 71. Positioning hole; 8. Upper mold head; 9. Core. DETAILED DESCRIPTION OF THE INVENTION

[0027] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0028] As Figure 1-2 shown, a wax mold structure for controlling the grains of a large-sized four-connected hollow single crystal blade includes: a gating system 1, a four-connected hollow blade 2 and a seed selector 3. The gating system 1 includes a bottom plate 11, a middle column 12, two runners 13 and a sprue cup 14. The upper and lower ends of the middle column 12 are respectively connected to the middle of the bottom plate 11 and the sprue cup 14. The sprue cup 14 is connected to the runner 13. Two four-connected hollow blades 2 are connected to each wax mold structure. The four-connected hollow blades 2 are distributed on both sides of the middle column 12. Each four-connected hollow blade 2 includes four blade bodies 21, and large flanges 22 and small flanges 23 are respectively provided at both ends of the four blade bodies 21. During installation, the large flange 22 end of the four-connected hollow blade 2 is located below, and the intake edge faces inward, that is, towards the side of the middle column 12. The small flange 23 is located above, and the small flange 23 end is connected to the runner 13 through a feeder piece 4. As solidification progresses and the temperature gradient gradually decreases, placing the large flange 22 below makes it easier to grow into a single crystal; the exhaust edge faces inward, so that the shapes of the large and small flanges gradually rise from inside to outside, while the temperature field distribution gradually rises from inside to outside, enabling sequential solidification of the large and small flanges and controlling the growth of dendrites in the large and small flanges.

[0029] As Figure 2 shown, the runner 13 includes an inclined section 131, an arc section 132 and a vertical section 133 that are smoothly butted in sequence. The vertical section 133 is connected to the feeder piece 4, and the axis line of the vertical section 133 coincides with the center line L of the four-connected hollow blade 2.

[0030] As Figure 1 、 4 shown, during installation, the solidification direction V of the four-connected hollow blade 2 is parallel to the center line L of the four-connected hollow blade 2, enabling control of the grains and precise control of the size. There are two seed selectors 3. The starting end of each seed selector 3 is connected to the bottom plate 11. The spiral end of the seed selector 3 is connected to the large flange 22 end of the four-connected hollow blade 2 through a seed guiding wafer 5. And an arc-shaped inner cladding plate 6 is provided between the four-connected hollow blade 2 and the middle column 12. The radian of the arc-shaped inner cladding plate 6 is an arc radian. The height of the arc-shaped inner cladding plate 6 is the same as the height of the four-connected hollow blade 2 group tree, that is, the top surface of the arc-shaped inner cladding plate 6 is flush with the top surface of the four-connected hollow blade 2. And in the top view state, the minimum distance t between the arc-shaped inner cladding plate 6 and the four-connected hollow blade 2 is 10 - 30 mm. The arc-shaped inner cladding plate 6 is used to increase the temperature gradient and the stability of the temperature field during the solidification of the four-connected hollow blade 2, enabling the four-connected hollow blade 2 to complete single crystal growth.

[0031] As Figure 2 、 3, as shown in Figures 5, in this example, the guide wafer 5 includes two triangular guide wafers 51 and two curved guide wafers 52. Two large sealing teeth 221 are provided on the outer end face of the large flange 22. The large sealing teeth 221 are connected to the spiral end of the crystal selector through the corresponding triangular guide wafers 51 to ensure the growth of dendrites. The two sides of the large flange 22 are conveniently connected to the outside of the corresponding triangular guide wafers 51 through the curved guide wafers 52. The curved guide wafers 52 protrude outwards. The curved guide wafers 52 are connected to the upper 1 / 3 of the triangular guide wafers 51 close to the upper part. On each curved guide wafer 52, there are 10 - 30 mm of hollowings with a size of 10 - 30 mm. The hollowing structure is rectangular. There are three hollowings on each curved guide wafer 52, which are n1, n2, n3, n4, n5, and n6 respectively. The setting of the hollowings ensures shell making (coating and sand sprinkling) and dendrite growth, which is beneficial to shell making forming. The feeder piece 4 includes a rectangular feeder piece 41 and a curved feeder piece 42. A small sealing tooth 231 is provided on the outer end face of the small flange 23. The end face of the small sealing tooth 231 is butted against the rectangular feeder piece 41 and the rectangular feeder piece 41 is of the same width as the small sealing tooth 231, and the height of the rectangular feeder piece 41 is greater than 30 mm. The two side edges of the small flange 23 are connected to the rectangular feeder piece 41 through the curved feeder pieces 42. The curved feeder pieces 42 are connected to the upper 1 / 3 of the rectangular feeder piece 41 close to the upper part. And there are three hollowings on each curved feeder piece 42, which are n7, n8, n9, n10, n11, and n12 respectively.

[0032] As Figure 2 , 6 shown, a lower die head 7 for positioning the core 9 is provided on the outer end face of the large flange 22. The lower die head 7 is arranged between the two large sealing teeth 221. There are four lower die heads 7, and the ratio of the exposed length of the lower die head 7 to the width of the core 9 is greater than 1:1. A positioning hole 71 with a length and width less than 1 / 2 of the contour of the lower die head is provided at the middle position of the lower die head 7. The positioning hole 71 is of a square structure, and the entire lower die head 7 is completely blank, which can prevent alloy liquid from infiltrating between the core 9 and the shell and inducing foreign crystals. An upper die head 8 for positioning the core 9 and being a free end is provided on the outer end face of the small flange 23, and a wax layer with a thickness of 0.3 - 0.6 mm is evenly coated on the surface of the upper die head 8. The lower die head 7 and the upper die head 8 are arranged at both ends of the core 9 inside the blade body 21.

[0033] Its working principle: By making the directional solidification direction of the four - joint hollow blade 2 consistent with the direction of its center line, the shrinkage deformation law with complex structure of the four - joint hollow blade 2 in the solidification direction is avoided. The large flange 22 is arranged below and the small flange 23 is arranged above, making full use of the characteristic of a relatively high temperature gradient at the initial stage of pulling to ensure the single - crystal growth of the large flange 22. And by adopting the way that the intake edge faces inwards, the flange gradually increases from inside to outside, and the temperature field near the flange gradually increases from inside to outside, which can ensure the sequential solidification of the flange. The setting of the arc - shaped inner cladding plate further ensures the temperature gradient and the stability of the temperature field;

[0034] The present invention realizes the grain growth of large-sized four-connected hollow single-crystal blades into complete single crystals, successfully fabricates large-sized four-connected hollow single-crystal blades, filling the gaps in this technical field at home and abroad; at the same time, it realizes the precise control of the size of large-sized four-connected hollow single-crystal blades. And in this embodiment, the first production and delivery of this type of blade at home and abroad have been completed.

[0035] Only some exemplary embodiments of the present invention have been described by way of illustration above. Without doubt, for those of ordinary skill in the art, various different ways can be used to modify the described embodiments without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the protection scope of the claims of the present invention.

Claims

1. A wax mold structure for controlling the grains of a large-sized four-connected hollow single crystal blade, characterized in that Comprising: A gating system, the gating system includes a bottom plate, a middle column, at least one runner and a sprue cup. The upper and lower ends of the middle column are respectively connected to the middle of the bottom plate and the sprue cup, and the sprue cup is connected to the runner; At least one four-connected hollow blade, which includes a blade body and large flanges and small flanges at both ends of the blade body. The solidification direction V of the four-connected hollow blade is parallel to its center line L. The large flange of the four-connected hollow blade is located below and the intake edge faces one side of the middle column. The small flange is located above and the end of the small flange is connected to the runner through a feeder piece. The feeder piece includes a rectangular feeder piece and a curved feeder piece. Small sealing teeth are provided on the outer end face of the small flange. The small sealing teeth are connected to the rectangular feeder piece and the rectangular feeder piece is of the same width as the small sealing teeth. The two side edges of the small flange are connected to the rectangular feeder piece through the curved feeder piece; At least one selector, the starting end of the selector is connected to the bottom plate, and the spiral end of the selector is connected to the large flange end of the four-connected hollow blade through a guiding wafer; An arc-shaped inner cladding plate, which is arranged between the four-connected hollow blade and the middle column.

2. The wax mold structure for controlling the grains of a large-sized four-connected hollow single crystal blade according to claim 1, wherein: The curved feeder piece is connected to the upper 1 / 3 of the rectangular feeder piece.

3. A wax mold structure for controlling the grains of a large-sized four-connected hollow single crystal blade according to claim 1, characterized in that: The guiding wafer includes two triangular guiding wafers and two curved guiding wafers. Two large sealing teeth are provided on the outer end face of the large flange. The large sealing teeth are respectively connected to the spiral end of the selector through the triangular guiding wafers. The two side edges of the large flange are connected to the corresponding triangular guiding wafers through the curved guiding wafers.

4. A wax mold structure for controlling the grains of a large-sized four-connected hollow single crystal blade according to claim 3, characterized in that: The curved guiding wafer is connected to the upper 1 / 3 of the triangular guiding wafer.

5. A wax mold structure for controlling crystal grains of a large-sized four-connected hollow single crystal blade according to claim 3, characterized in that: Hollow openings with a size of 10-30mm are provided on the curved guiding wafer and the curved feeder piece at intervals of 10-30mm.

6. A wax mold structure for controlling crystal grains of a large-sized four-connected hollow single crystal blade according to claim 1, characterized in that: A lower mold head for positioning the core is provided on the outer end face of the large flange. The ratio of the length of the lower mold head exposed to the width of the core is greater than 1:

1. A positioning hole with a length and width less than 1 / 2 of the contour of the lower mold head is provided at the middle position of the lower mold head.

7. A wax mold structure for controlling the crystal grains of a large-size four-connected hollow single crystal blade according to claim 6, characterized in that: An upper mold head with a free end is provided on the outer end face of the small flange. A wax layer with a thickness of 0.3-0.6mm is evenly coated on the surface of the upper mold head.

8. A wax mold structure for controlling the grains of a large-sized four-connected hollow single crystal blade according to claim 1, characterized in that: The top surface of the arc-shaped inner cladding plate is flush with the upper end of the four-connected hollow blade, and the minimum distance between the arc-shaped inner cladding plate and the four-connected hollow blade is 10-30mm.

9. A wax mold structure for controlling the grains of a large-sized four-connected hollow single crystal blade according to any one of claims 1-8, characterized in that: The runner includes an inclined section, an arc section and a vertical section that are smoothly butted in sequence. The vertical section is connected to the feeder piece and the axis line of the vertical section coincides with the center line L of the four-connected hollow blade.

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