A complex hollow single crystal turbine blade wax mold wall thickness control method and wax mold

Abstract

The present application relates to the technical field of precision casting, and more particularly to a complex hollow single crystal turbine blade wax mold wall thickness control method and a wax mold, which comprises the following steps: obtaining the section surface size corresponding to the ceramic core and the wax mold wall thickness point, screening the ceramic core; then, using the cooperation of the positioning boss and the positioning hole, positioning the screened ceramic core in the wax mold mold, injecting wax into the wax mold mold, and obtaining the blade wax mold; detecting the blade wax mold wall thickness and the corresponding casting wall thickness and obtaining the wall thickness change value; finally, according to the wall thickness change value, obtaining the maximum value and the minimum value of the wall thickness of each detection point of the wax mold, and accurately controlling the wall thickness of the subsequent production of the wax mold, so as to avoid the casting wall thickness out-of-tolerance caused by improper control of the wax mold wall thickness, and improve the casting wall thickness qualified rate. The present application solves the problem that the wax mold wall thickness of the single crystal turbine working blade cannot meet the process requirements due to the shrinkage of the ceramic core.

Description

Technical Field

[0001] This invention relates to the field of precision casting technology, specifically to a method for controlling the wall thickness of a wax mold for complex hollow single-crystal turbine blades and the wax mold itself. Background Technology

[0002] Hollow turbine blades are core hot-end components of aero-engines, and their performance directly determines the engine's overall efficiency and reliability. In extreme operating environments, blades must withstand the impact of high-temperature, high-pressure airflow while maintaining sufficient strength and durability to ensure safe engine operation. Therefore, the design and control of blade wall thickness are particularly important, directly affecting the blade's strength and lifespan. Whether the blade wall thickness meets design requirements is a crucial indicator of turbine blade strength, primarily determined through core-mold positioning and matching. During blade manufacturing, the ceramic core, as a key forming tool, directly impacts the uniformity and yield rate of the blade wax mold's wall thickness due to its dimensional control and positioning accuracy. However, the ceramic core undergoes shrinkage deformation during pressing and sintering, determined by the core material's composition, particle size distribution, and structural characteristics. This shrinkage deformation leads to positioning deviations of the core in the wax mold, thus affecting the wall thickness accuracy of the blade wax mold. To address this issue, the industry has proposed a series of technical methods, such as adjusting the core position, reverse adjustment of the positioning element dimensions, and grinding the core head and adhering the core support. Adjusting the core position controls the wall thickness distribution of the wax pattern blades by adjusting the core's position within the outer mold. However, this method increases the complexity of mold design and requires higher precision and quality control during mold manufacturing. Reverse adjustment of the positioning element dimensions involves establishing a ceramic core positioning error transmission model and a reverse adjustment model to determine the mapping relationship between the ceramic core wall thickness deviation and the compensation amount of the positioning element. Then, measurement techniques such as ultrasonic pulse reflection are used to measure the wall thickness of the wax pattern, and the dimensions of the ceramic core positioning element are reversely adjusted based on the measurement results. This method can effectively calculate the dimensional compensation amount of the ceramic core positioning element, thereby improving the performance of hollow turbine blade wax patterns. While improving molding efficiency and wall thickness accuracy, reverse adjustment of positioning element dimensions requires the establishment of precise error propagation and reverse adjustment models. This demands that technicians possess strong mathematical and physical modeling abilities. Furthermore, advanced measurement techniques, such as ultrasonic pulse reflection, are needed to accurately measure the wall thickness of the wax pattern, further increasing the complexity of the technology. Even minor errors during operation can lead to significant deviations in the final result. Grinding the core head and attaching the core support reduces the gap between the core and the mold, improving positioning accuracy. This method is typically combined with adjusting the core position and reverse adjusting the positioning element dimensions to achieve optimal wall thickness control. However, this approach is complex, inefficient, and requires significant time and manpower, resulting in high production costs.

[0003] Chinese invention patent CN115351224A discloses a method for solving the wall thickness problem of complex hollow single-crystal blades. The method includes wax pattern pressing: placing a ceramic core into a mold, setting support and positioning points in the mold to restrict the core's freedom of movement, and injecting molten wax into the wax pattern mold using an injection molding process to obtain a molded wax pattern. The molded wax pattern is then removed from the mold and shaped. X-ray wall thickness detection is performed on the wax patterns that pass X-ray inspection. Wax pattern assembly is then performed. Finally, the mold shell is placed in a single-crystal chamber for casting. The method is simple to operate, using six-point positioning to ensure the wall thickness of complex hollow single-crystal blades, and bottom-pouring casting to ensure qualified castings. It eliminates the need for core positioning and wax pattern core support adjustments required in traditional methods, effectively improving the production efficiency of complex hollow single-crystal blade castings. However, this method only involves positioning the ceramic core surface and does not achieve control over the ceramic core size. There is a problem of poor positioning consistency caused by ceramic core shrinkage. Further adjustments to the positioning system or manual grinding of the core head or application of wax sheets are required for correction. The process is complex and inefficient.

[0004] Therefore, how to control the size of the ceramic core and combine it with the precise positioning of the ceramic core in the wax mold to ensure that the wall thickness of the wax mold for the single-crystal turbine working blade meets the strict process requirements remains a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the problem in existing technologies where the wall thickness of the wax mold for single-crystal turbine blades cannot meet process requirements due to the shrinkage of the ceramic core, this invention provides a method for controlling the wall thickness of the wax mold for complex hollow single-crystal turbine blades and a wax mold thereof.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention provides a method for controlling the wall thickness of wax molds for complex hollow single-crystal turbine blades, comprising:

[0008] Obtain the profile dimensions of the cross section corresponding to the thickness point of the ceramic core and the wax model;

[0009] The ceramic cores are selected based on the profile dimensions of the cross-section corresponding to the thickness point of the wax mold.

[0010] The selected ceramic core is placed in the wax mold for positioning; during positioning, a positioning hole is provided in the middle of the tenon of the ceramic core, and a positioning protrusion is provided in the wax mold at the position corresponding to the positioning hole.

[0011] After positioning is completed, wax is poured into the wax mold to obtain the blade wax model;

[0012] The wall thickness of the blade wax model is detected, and the blade wax model is used for casting to obtain the casting. The wall thickness of the casting is detected at the corresponding detection points of the blade wax model.

[0013] The wall thickness variation value is obtained based on the wall thickness of the blade wax model and the wall thickness of the casting;

[0014] Based on the wall thickness variation, obtain the maximum and minimum values ​​of the wall thickness at each detection point of the wax model;

[0015] The wall thickness of the wax mold in subsequent production is controlled based on the maximum and minimum values ​​of the wall thickness at each detection point of the wax mold.

[0016] Optionally, the six-point positioning method can be used to obtain the profile dimensions of the cross section corresponding to the thickness points of the ceramic core and the wax model.

[0017] Optionally, in the process of obtaining the profile dimensions of the cross section corresponding to the thickness point of the ceramic core and the wax mold using the six-point positioning method, the selected positioning points include the first and second positioning points set on the tenon of the ceramic core, the third positioning point set in the back basin direction, the fourth positioning point set in the exhaust direction, the fifth positioning point set in the intake direction, and the sixth positioning point set in the radial direction of the ceramic core.

[0018] Optionally, during the process of positioning the selected ceramic core in the wax mold, the selection of the positioning point is consistent with the positioning point in the six-point positioning method.

[0019] Optionally, the method for positioning the selected ceramic core in the wax mold is as follows:

[0020] Positioning pins are used to position the fourth and fifth positioning points respectively, fixing the position of the ceramic core in the wax mold pressing mold in the direction of air intake and exhaust;

[0021] Place the positioning protrusion of the wax mold into the positioning hole of the ceramic core to fix the tenon of the ceramic core in the position of the wax mold;

[0022] The ceramic core is positioned in the height direction within the wax mold by using the positioning method to locate the position corresponding to the sixth positioning point.

[0023] Positioning pins are used to locate the positions corresponding to the first, second, and third positioning points, respectively, to fix the position of the ceramic core in the back of the wax mold, thus completing the positioning of the ceramic core in the wax mold.

[0024] Optionally, the positioning hole is a square hole, with a length and width of 5-6 mm.

[0025] Optionally, ultrasonic testing can be used to test the wall thickness of the blade wax model and the casting.

[0026] Optionally, the method for obtaining the wall thickness variation value based on the wall thickness of the blade wax model and the wall thickness of the casting is as follows:

[0027]

[0028] in, a This represents the wall thickness variation value. a 2 represents the wall thickness of the blade casting at a certain testing point. a 1 represents the wall thickness of the wax model at the corresponding blade casting wall thickness detection point.

[0029] Optionally, the method for obtaining the maximum and minimum values ​​of the wall thickness at each detection point of the wax model based on the wall thickness variation value is as follows:

[0030]

[0031] in, a min The minimum design requirement for the wall thickness detection point b of the blade casting is given. a max The maximum value required for the wall thickness detection point b of the blade casting is specified in the design. a 3. Reserve grinding allowance for the blade casting wall thickness detection point b; A min This represents the minimum wall thickness control value at the corresponding wall thickness detection point b on the blade wax model. A max This represents the maximum wall thickness control value at the wall thickness detection point b corresponding to the blade wax model. a This represents the change in wall thickness from the wax model to the corresponding wall thickness detection point b on the casting.

[0032] The present invention also provides a wax mold, wherein the wall thickness is controlled by the above method.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention discloses a method for controlling the wall thickness of wax molds for complex hollow single-crystal turbine blades. The method involves obtaining the profile dimensions of the cross-section corresponding to the wall thickness points of the ceramic core and screening the ceramic cores; then, positioning the screened ceramic cores in the wax mold and injecting wax into the mold to obtain the blade wax mold; detecting the wall thickness of the blade wax mold and the corresponding casting wall thickness and obtaining the wall thickness variation value; finally, based on the wall thickness variation value, obtaining the maximum and minimum values ​​of the wall thickness at each detection point of the wax mold to precisely control the wall thickness of the wax mold in subsequent production, avoiding casting wall thickness deviations caused by improper wax mold wall thickness control requirements, and improving the casting wall thickness qualification rate. This method, when positioning the ceramic core in the wax mold, uses a positioning hole at the center of the tenon of the ceramic core and a corresponding positioning protrusion in the wax mold. The positioning hole and protrusion work together to locate the center plane of the thicker parts of the ceramic core. Utilizing the principle of the ceramic core shrinking towards the center, this method avoids the positioning deviation of the ceramic core in the wax mold caused by the unstable shrinkage of the thicker parts during core surface positioning. This minimizes the impact of ceramic core shrinkage on positioning, ensuring the center plane of the ceramic core is positioned in the wax mold while reducing positioning deviation caused by ceramic core surface shrinkage deformation. This avoids problems such as uneven wax mold wall thickness and high scrap rate caused by positioning deviation due to ceramic core shrinkage. This method reduces the likelihood of manual adjustments to the ceramic core's positioning in the mold, such as grinding the core head, attaching wax sheets to the core head, or adjusting the positioning pins in the outer mold, thus reducing human factors influencing the production process and significantly improving product consistency and production efficiency.

[0035] Using the six-point positioning method to obtain the cross-sectional dimensions corresponding to the thickness points of the ceramic core and the wax mold can significantly improve the measurement accuracy and obtain the cross-sectional dimensions of the ceramic core and the wax mold more quickly. This not only shortens the measurement time but also provides timely data support for subsequent process adjustments, which helps to accelerate the production schedule.

[0036] In the process of obtaining the cross-sectional dimensions of the ceramic core and the wax mold wall thickness points using the six-point positioning method, the selected positioning points include a first and second positioning point set on the tenon of the ceramic core, a third positioning point set in the back basin direction, a fourth positioning point set in the exhaust direction, a fifth positioning point set in the intake direction, and a sixth positioning point set in the radial direction of the ceramic core. Among these, the first and second positioning points are tenon positioning points. The tenon is a critical part of the ceramic core, and its shape and size are crucial to positioning accuracy. By setting two positioning points on the tenon, the stability and accuracy of the ceramic core during measurement can be ensured. These two positioning points can also effectively restrict the degrees of freedom of the ceramic core in the translational and rotational directions, thereby improving positioning accuracy. The third, fourth, and fifth positioning points are positioning points in the back basin, exhaust, and intake directions, respectively, ensuring the all-around stability of the ceramic core during measurement. They also help calibrate the orientation of the ceramic core, ensuring that the core is in the correct posture during measurement. The sixth positioning point is a radial positioning point, which can further restrict the degree of freedom of the ceramic core in the radial direction, thereby improving the positioning accuracy and stability. At the same time, it also helps to ensure the correct contact and alignment between the ceramic core and the measuring equipment during the measurement process.

[0037] During the process of positioning the selected ceramic core in the wax mold, the selection of positioning points is consistent with the positioning points in the six-point positioning method. This ensures the consistency of the ceramic core wall thickness before pressing the wax mold during the inspection and wax mold positioning of the ceramic core. It also precisely controls the dimensions of the ceramic core that affect the wax mold wall thickness, reducing the scrap rate of the blade wax mold and casting wall thickness, and helping to ensure the reliability of positioning. In the wax mold positioning of the ceramic core, stable support and reliable positioning are key to ensuring casting quality. Using consistent positioning points can avoid casting defects caused by positioning deviations, such as dimensional deviations and shape distortions. At the same time, using the same positioning points simplifies the operation process, reduces positioning time, improves production efficiency, and reduces production costs.

[0038] During the process of positioning the selected ceramic core in the wax mold, positioning pins are used to locate the positions corresponding to the fourth and fifth positioning points, fixing the position of the ceramic core in the air intake and exhaust direction within the wax mold. This precise positioning helps ensure the correct posture of the ceramic core in the mold, preventing displacement or deformation during subsequent processing. The positioning protrusions of the wax mold are then inserted into the positioning holes of the ceramic core, fixing the tenon of the ceramic core in the wax mold and firmly securing the tenon in the wax mold. While positioning the ceramic core within the mold, it also helps maintain precise alignment between the ceramic core and the wax mold. Using positioning pins to locate the ceramic core at the sixth positioning point fixes its position in the height direction within the wax mold, ensuring consistent height and preventing height errors during processing. Positioning pins are then used to locate the first, second, and third positioning points, fixing the ceramic core's position in the back direction within the wax mold. This comprehensive positioning method further enhances the stability and positioning accuracy of the ceramic core within the mold.

[0039] The positioning hole is a square hole, with a length and width of 5-6 mm. The square hole design allows the positioning protrusion to be inserted and fixed more accurately, ensuring precise alignment between the ceramic core and the wax mold, and helping to reduce errors caused by inaccurate positioning during processing. The shape of the square hole also makes the positioning protrusion more stable in the hole, preventing it from wobbling or shifting.

[0040] Using ultrasonic testing to detect the wall thickness of blade wax molds and castings is more efficient and yields more accurate results.

[0041] A wax mold is disclosed, employing the aforementioned method to control wall thickness. This mold has been applied in the production of single-crystal turbine blades for a certain type of gas turbine and a certain type of aero-engine. The wax mold exhibits uniform wall thickness, resulting in a high and stable pass rate for casting wall thickness, thus saving the workshop significant manpower and material resources. Attached Figure Description

[0042] Figure 1 This is a flowchart illustrating a method for controlling the wall thickness of a wax mold for complex hollow single-crystal turbine blades according to the present invention.

[0043] Figure 2 This is a schematic diagram of the six-point positioning of the ceramic core using the six-point positioning method in an embodiment of the present invention.

[0044] Figure 3 This is a schematic diagram illustrating the positioning method of the ceramic core in the wax mold according to the present invention.

[0045] Figure 4This is a side view showing the positioning method of the ceramic core in the wax mold according to the present invention.

[0046] Figure 5 This is an enlarged cross-sectional view of the ceramic core tenon AA of the ceramic core of the present invention.

[0047] Wherein, 1-first positioning point, 2-second positioning point, 3-third positioning point, 4-fourth positioning point, 5-fifth positioning point, 6-sixth positioning point, 7-positioning hole. Detailed Implementation

[0048] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0049] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0050] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0051] See Figure 1 This invention discloses a method for controlling the wall thickness of a wax model of a complex hollow single-crystal turbine blade, characterized by comprising:

[0052] S1: Obtain the profile dimensions of the cross-section corresponding to the thickness point of the ceramic core and the wax model wall, specifically:

[0053] Optionally, the six-point positioning method can be used to obtain the profile dimensions of the cross-section corresponding to the thickness points of the ceramic core and the wax model, see [reference]. Figure 2In the process of obtaining the profile dimensions of the cross section corresponding to the thickness point of the ceramic core and the wax mold using the six-point positioning method, the selected positioning points include the first positioning point 1 and the second positioning point 2 set on the tenon of the ceramic core, the third positioning point 3 set in the back basin direction, the fourth positioning point 4 set in the exhaust direction, the fifth positioning point 5 set in the intake direction, and the sixth positioning point 6 set in the radial direction of the ceramic core.

[0054] S2: Based on the surface dimensions of the cross section corresponding to the thickness point of the wax mold, the ceramic cores are screened; according to the surface dimension tolerance requirements, the ceramic cores that meet the surface dimension tolerance requirements are selected as qualified ceramic cores for the next step of positioning in the wax mold.

[0055] S3: The selected ceramic core is placed in the wax mold for positioning. During positioning, a positioning hole 7 is provided at the center of the tenon of the ceramic core, and a positioning protrusion is provided in the wax mold corresponding to the positioning hole 7. During this positioning process, the selection of the positioning point is consistent with the positioning point in the six-point positioning method. Preferably, the positioning hole is a square hole with a length and width of 5-6 mm. The gap between the mold protrusion's air intake / exhaust direction and the corresponding surface of the ceramic core is approximately 0.05 mm. The distance from a point on the positioning surface of the tenon positioning hole to the center surface of the ceramic core in the width direction is less than or equal to 1.5 mm. The radial gap between the positioning protrusion and the ceramic core positioning hole 7 is 0.20-0.45 mm. See [reference needed]. Figure 3 and Figure 4 Specifically:

[0056] The positioning targets are used to locate the positions corresponding to the fourth positioning point 4 and the fifth positioning point 5 respectively, and to fix the position of the ceramic core in the wax mold pressing mold in the direction of air intake and exhaust;

[0057] Place the positioning protrusion of the wax mold into the positioning hole 7 of the ceramic core to fix the position of the tenon of the ceramic core in the wax mold;

[0058] The ceramic core is positioned in the height direction within the wax mold by using the positioning method to locate the position corresponding to the sixth positioning point 6.

[0059] Positioning pins are used to locate the positions corresponding to the first positioning point 1, the second positioning point 2, and the third positioning point 3 respectively, thereby fixing the position of the ceramic core in the back of the wax mold and completing the positioning of the ceramic core in the wax mold.

[0060] S4: After positioning, wax is poured into the wax mold to obtain the blade wax model, specifically:

[0061] Molten wax is injected into a wax mold to obtain a shaped wax mold. The shaped wax mold is then removed from the wax mold and shaped to obtain a blade wax mold.

[0062] S5: Detect the wall thickness of the blade wax model, and use the blade wax model for casting to obtain the casting. Then, detect the corresponding wall thickness detection points on the blade wax model to determine the wall thickness of the casting. Specifically:

[0063] The wall thickness at each test point of the blade wax model is obtained by using ultrasonic testing. The wax model is then assembled and cast to obtain the casting. The corresponding test points of the casting and the wax model are tested by ultrasonic testing to obtain the wall thickness at the corresponding test points of the casting.

[0064] S6: Obtain the wall thickness variation value based on the wall thickness of the blade wax model and the casting wall thickness, specifically:

[0065]

[0066] in, a This represents the wall thickness variation value. a 2 represents the wall thickness of the blade casting at a certain testing point. a 1 represents the wall thickness of the wax model at the corresponding blade casting wall thickness detection point.

[0067] S7: Based on the wall thickness variation value, obtain the maximum and minimum values ​​of the wall thickness at each detection point of the wax model, specifically as follows:

[0068]

[0069] in, a min The minimum design requirement for the wall thickness detection point b of the blade casting is given. a max The maximum value required for the wall thickness detection point b of the blade casting is specified in the design. a 3. Reserve grinding allowance for the blade casting wall thickness detection point b; A min This represents the minimum wall thickness control value at the corresponding wall thickness detection point b on the blade wax model. A max This represents the maximum wall thickness control value at the wall thickness detection point b corresponding to the blade wax model. a The value represents the change in wall thickness from the wax model to the corresponding wall thickness detection point b on the casting. Detection point b is a point on the blade casting.

[0070] S8: Based on the maximum and minimum values ​​of the wall thickness at each inspection point of the wax model, control the wall thickness of the wax model in subsequent production. Specifically, after obtaining the maximum and minimum values ​​of the wall thickness at each inspection point of the wax model, the thickness of the wax model mold at the corresponding inspection point can be checked according to the range of the maximum and minimum values. If the thickness is less than the minimum value at this inspection point, it is unqualified. If it is greater than the maximum value at this inspection point, it needs to be polished and adjusted so that its thickness meets the requirements of the maximum and minimum values.

[0071] Example 1

[0072] See Figures 2 to 5 Taking a single-crystal turbine blade of a gas turbine as an example, the wall thickness tolerance of the casting is ±0.25mm, the width of the ceramic core tenon is about 30mm, and the height of the ceramic core is about 130mm.

[0073] First, the dimensions of the cross sections AA-AA, AB-AB, AC-AC, and AD-AD corresponding to the wall thickness points of the ceramic core and the wax mold were measured using a six-point positioning method. The dimensional tolerance was ±0.20 mm. The six positioning points in the six-point positioning method were consistent with the subsequent positioning of the ceramic core in the wax mold. These points were: the first positioning point 1 and the second positioning point 2 located on the tenon positioning surface of the ceramic core; the third positioning point 3 located in the direction of the basin back; the fourth positioning point 4 and the fifth positioning point 5 located in the exhaust and intake directions respectively; and the sixth positioning point 6 located in the radial direction of the ceramic core.

[0074] After obtaining the above-mentioned surface dimensions, place the ceramic core with qualified surface dimensions into the wax mold to press the wax mold. In the wax mold, the ceramic core is fixed in the wax mold using a six-point positioning method:

[0075] Positioning pins are used at the fourth positioning point 4 and the fifth positioning point 5 on the side of the tenon positioning hole to fix the ceramic core in the wax mold molding die for the air intake and exhaust direction. The positioning protrusion of the blade wax mold molding die is placed into the positioning hole 7 at the tenon of the ceramic core to fix the positioning of the ceramic core tenon in the wax mold. The blade tip of the ceramic core is positioned by the positioning pin located at the fourth positioning point 4. The positioning hole 7 on the tenon of the ceramic core is designed as a rectangular hole with a specification of 5*6mm. The gap between the air intake and exhaust direction of the wax mold protrusion and the corresponding surface of the ceramic core is 0.05mm. The distance from a point on the positioning surface of the positioning hole 7 on the tenon to the center surface of the ceramic core in the width direction is less than or equal to 1.5mm.

[0076] The ceramic core is positioned in the wax mold in the blade height direction by placing the positioning pin into the gap of the ceramic core blade tip and contacting the sixth positioning point 6. The radial gap between the positioning protrusion and the positioning hole 7 is 0.45mm.

[0077] The basin-back orientation is positioned using positioning pins at the tenon positioning surfaces where the first positioning point 1, the second positioning point 2, and the third positioning point 3 are located, thus fixing the ceramic core in the basin-back orientation within the wax mold. Wax is then injected into the blade wax mold to obtain the blade wax model.

[0078] The wall thickness at each test point of the blade wax model is obtained by using ultrasonic testing. The wax model is then assembled and cast to obtain the casting. The corresponding test points of the casting and the wax model are tested by ultrasonic testing to obtain the wall thickness at the corresponding test points of the casting.

[0079] Based on the wall thickness of the blade wax model and the wall thickness of the casting, obtain the wall thickness variation value:

[0080]

[0081] in, a This represents the wall thickness variation value. a 2 represents the wall thickness of the blade casting at a certain testing point. a 1 represents the wall thickness of the wax model at the corresponding blade casting wall thickness detection point.

[0082] Based on the wall thickness variation, obtain the maximum and minimum wall thickness values ​​at each detection point of the wax model:

[0083]

[0084] in, a min The minimum design requirement for the wall thickness detection point b of the blade casting is given. a max The maximum design requirement for point b, which is the wall thickness detection point of the blade casting; A min This represents the minimum wall thickness control value at the corresponding wall thickness detection point b on the blade wax model. A max This represents the maximum wall thickness control value at the wall thickness detection point b corresponding to the blade wax model. a This represents the change in wall thickness from the wax model to the corresponding wall thickness detection point b on the casting.

[0085] After obtaining the maximum and minimum wall thickness values ​​at each test point of the wax model, the thickness of the wax model mold at the corresponding test point can be tested according to the range of the maximum and minimum values. If the thickness is less than the minimum value at this test point, it is unqualified. If it is greater than the maximum value at this test point, it needs to be polished and adjusted so that its thickness meets the requirements of the maximum and minimum values.

[0086] According to the above requirements, the wall thickness of the wax model is tested and controlled to obtain a wax model of the part with a wall thickness that meets the requirements.

[0087] Example 2

[0088] See Figures 2 to 5 Taking a single-crystal turbine working blade of a certain aircraft as an example, the wall thickness tolerance is ±0.20mm, the width of the widest part of the ceramic core tenon is about 55mm, and the height of the ceramic core is about 100mm.

[0089] A six-point positioning method was used to inspect the surface dimensions of the cross sections AA-AA, AB-AB, and AC-AC corresponding to the wall thickness points of the ceramic core and the wax model. The surface dimension tolerance was ±0.15mm. The six positioning points in the six-point positioning method are consistent with the positioning of the ceramic core in the wax model mold, namely: the first positioning point 1 and the second positioning point 2 on the ceramic core tenon positioning surface; the third positioning point 3 located in the direction of the basin back; the fourth positioning point 4 and the fifth positioning point 5 located in the exhaust direction and the intake direction respectively; and the sixth positioning point 6 located in the radial direction of the ceramic core.

[0090] The appropriately sized ceramic core is placed in the wax mold to press the wax model. Within the wax mold, the ceramic core is fixed using a six-point positioning method.

[0091] After obtaining the above-mentioned surface dimensions, place the ceramic core with qualified surface dimensions into the wax mold to press the wax mold. In the wax mold, the ceramic core is fixed in the wax mold using a six-point positioning method:

[0092] Positioning pins are used at the fourth positioning point 4 and the fifth positioning point 5 on the side of the tenon positioning hole to fix the ceramic core in the wax mold molding die for the air intake and exhaust direction. The positioning protrusion of the blade wax mold molding die is placed into the positioning hole 7 at the tenon of the ceramic core to fix the positioning of the ceramic core tenon in the wax mold. The blade tip of the ceramic core is positioned by the positioning pin located at the fourth positioning point 4. The positioning hole 7 on the tenon of the ceramic core is designed as a rectangular hole with a specification of 5*5mm. The gap between the air intake and exhaust direction of the wax mold protrusion and the corresponding surface of the ceramic core is 0.05mm. The distance from a point on the positioning surface of the positioning hole 7 on the tenon to the center surface of the ceramic core in the width direction is less than or equal to 1.5mm.

[0093] The ceramic core is positioned in the wax mold in the blade height direction by placing the positioning pin into the gap of the ceramic core blade tip and contacting the sixth positioning point 6. The radial gap between the positioning protrusion and the positioning hole 7 is 0.2mm.

[0094] The basin back direction is positioned using positioning pins on the tenon positioning surfaces at the first positioning point 1, the second positioning point 2, and the third positioning point 3, thus fixing the ceramic core in the basin back direction within the wax mold. (Wax is injected into the blade wax mold to obtain the blade wax mold.)

[0095] The wall thickness at each test point of the blade wax model is obtained by using ultrasonic testing. The wax model is then assembled and cast to obtain the casting. The corresponding test points of the casting and the wax model are tested by ultrasonic testing to obtain the wall thickness at the corresponding test points of the casting.

[0096] Based on the wall thickness of the blade wax model and the wall thickness of the casting, obtain the wall thickness variation value:

[0097]

[0098] in, a This represents the wall thickness variation value. a 2 represents the wall thickness of the blade casting at a certain testing point. a 1 represents the wall thickness of the wax model at the corresponding blade casting wall thickness detection point.

[0099] Based on the wall thickness variation, obtain the maximum and minimum wall thickness values ​​at each detection point of the wax model:

[0100]

[0101] in, a min The minimum design requirement for the wall thickness detection point b of the blade casting is given. a max The maximum value required for the wall thickness detection point b of the blade casting is specified in the design. a 3. Reserve grinding allowance for the blade casting wall thickness detection point b; A min This represents the minimum wall thickness control value at the corresponding wall thickness detection point b on the blade wax model. A max This represents the maximum wall thickness control value at the wall thickness detection point b corresponding to the blade wax model. a This represents the change in wall thickness from the wax model to the corresponding wall thickness detection point b on the casting.

[0102] After obtaining the maximum and minimum wall thickness values ​​at each test point of the wax model, the thickness of the wax model mold at the corresponding test point can be tested according to the range of the maximum and minimum values. If the thickness is less than the minimum value at this test point, it is unqualified. If it is greater than the maximum value at this test point, it needs to be polished and adjusted so that its thickness meets the requirements of the maximum and minimum values.

[0103] According to the above requirements, the wall thickness of the wax model is tested and controlled to obtain a wax model of the part with a wall thickness that meets the requirements.

[0104] A wax mold is disclosed, employing the aforementioned method to control wall thickness. This mold has been applied in the production of single-crystal turbine blades for a certain type of gas turbine and a certain type of aero-engine. The wax mold exhibits uniform wall thickness, resulting in a high and stable pass rate for casting wall thickness, thus saving the workshop significant manpower and material resources.

[0105] In summary, this invention provides a method for controlling the wall thickness of wax molds for complex hollow single-crystal turbine blades, and a wax mold itself. It proposes a method using the center surface of the thickest part of a ceramic core for positioning. Utilizing the principle of the ceramic core shrinking towards the center, this avoids the problem of the ceramic core shifting in the outer mold due to unstable shrinkage of the thickest part during core surface positioning, which leads to uneven wax mold wall thickness and high scrap rates. This method reduces the likelihood of manually adjusting the ceramic core's positioning in the mold, such as grinding the core head, attaching wax sheets to the core head, or adjusting the positioning pins of the ceramic core in the outer mold. This reduces human factors influencing the production process, significantly improving product consistency and production efficiency. By obtaining the wall thickness variation at corresponding detection points on the casting and the corresponding wax mold, the minimum and maximum values ​​for wax mold wall thickness control can be obtained, allowing for precise control of the blade wax mold wall thickness. This avoids casting wall thickness deviations caused by improper wax mold wall thickness control requirements, improving the casting wall thickness pass rate. This method has been applied to the production of single-crystal turbine blades for a certain type of gas turbine and single-crystal turbine blades for a certain type of aero-engine. The wax mold wall thickness is uniform, and the qualified rate of the casting wall thickness is high and stable, saving the workshop a lot of manpower and material resources.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.

Claims

1. A method for controlling the wall thickness of a wax model of a complex hollow single-crystal turbine blade, characterized in that, include: Obtain the profile dimensions of the cross section corresponding to the thickness point of the ceramic core and the wax mold; use the six-point positioning method to obtain the profile dimensions of the cross section corresponding to the thickness point of the ceramic core and the wax mold. In the process of obtaining the profile dimensions of the cross section corresponding to the thickness point of the ceramic core and the wax mold using the six-point positioning method, the selected positioning points include the first and second positioning points set on the tenon of the ceramic core, the third positioning point set in the back basin direction, the fourth positioning point set in the exhaust direction, the fifth positioning point set in the intake direction, and the sixth positioning point set in the radial direction of the ceramic core. The ceramic cores are selected based on the profile dimensions of the cross-section corresponding to the thickness point of the wax mold. The selected ceramic core is placed in the wax mold for positioning. During positioning, a positioning hole is provided in the middle of the tenon of the ceramic core, and a positioning protrusion is provided in the wax mold at the corresponding position of the positioning hole. The selection of positioning points during the positioning process of placing the selected ceramic core in the wax mold is consistent with the positioning points in the six-point positioning method. The specific method is as follows: Positioning pins are used to position the fourth and fifth positioning points respectively, fixing the position of the ceramic core in the wax mold pressing mold in the direction of air intake and exhaust; Place the positioning protrusion of the wax mold into the positioning hole of the ceramic core to fix the tenon of the ceramic core in the position of the wax mold; The ceramic core is positioned in the height direction within the wax mold by using the positioning method to locate the position corresponding to the sixth positioning point. Positioning pins are used to position the first, second, and third positioning points respectively, fixing the position of the ceramic core in the back of the wax mold in the direction of the bowl, thus completing the positioning of the ceramic core in the wax mold. After positioning is completed, wax is poured into the wax mold to obtain the blade wax model; The wall thickness of the blade wax model is detected, and the blade wax model is used for casting to obtain the casting. The wall thickness of the casting is detected at the corresponding detection points of the blade wax model. The wall thickness variation value is obtained based on the wall thickness of the blade wax model and the wall thickness of the casting; Based on the wall thickness variation, the maximum and minimum values ​​of the wall thickness at each detection point of the wax model are obtained, specifically as follows: A min = a min + a 3+ a A max = a max + a 3+ a in, a min The minimum design requirement for the wall thickness detection point b of the blade casting is given. a max The maximum value required for the wall thickness detection point b of the blade casting is specified in the design. a 3. Reserve grinding allowance for the blade casting wall thickness detection point b; A min This represents the minimum wall thickness control value at the corresponding wall thickness detection point b on the blade wax model. A max This represents the maximum wall thickness control value at the wall thickness detection point b corresponding to the blade wax model. a The value representing the change in wall thickness from the wax model to the corresponding wall thickness detection point b on the casting; The wall thickness of the wax mold in subsequent production is controlled based on the maximum and minimum values ​​of the wall thickness at each detection point of the wax mold.

2. The method for controlling the wall thickness of wax molds for complex hollow single-crystal turbine blades according to claim 1, characterized in that, The positioning hole is a square hole, with a length and width of 5-6 mm.

3. The method for controlling the wall thickness of wax molds for complex hollow single-crystal turbine blades according to claim 1, characterized in that, The wall thickness of the blade wax model and the casting was detected using ultrasonic testing.

4. The method for controlling the wall thickness of wax molds for complex hollow single-crystal turbine blades according to claim 1, characterized in that, The method for obtaining the wall thickness variation value based on the wall thickness of the blade wax model and the wall thickness of the casting is as follows: in, a This represents the wall thickness variation value. a 2 represents the wall thickness of the blade casting at a certain testing point. a 1 represents the wall thickness of the wax model at the corresponding blade casting wall thickness detection point.

5. A wax mold, characterized in that, The wall thickness is controlled by the method described in any one of claims 1-4.

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