Wax pattern and method for improving dimensional accuracy of single crystal superalloy castings

Abstract

This invention discloses a wax model and method for improving the dimensional accuracy of single-crystal high-temperature alloy castings. The wax model has four spiral crystal selectors evenly arranged circumferentially on its base. Each spiral crystal selector is sequentially connected to a crystal-driving cone, a single-crystal casting, and a sprue. The tops of the four sprues are connected to a pouring cup. A vertical support column is positioned between two adjacent single-crystal castings. A grid wax sheet is suspended on each side of each single-crystal casting, and each grid wax sheet is fixedly connected to the vertical support column by two horizontal support columns. The method includes the following steps: pressing the wax model using a wax pressing method; preparing a ceramic shell using a precision investment casting method; placing the ceramic shell in a directional solidification furnace and casting it using a directional solidification method. The grid wax shell of this invention forms an integral part with the single-crystal casting shell. During casting and directional solidification, the grid wax sheet acts as a reinforcing rib, preventing deformation of the single-crystal casting shell and improving the dimensional accuracy of the casting.

Description

Technical Field

[0001] This invention belongs to the field of preparation technology of single crystal high-temperature alloy castings, specifically relating to a wax model and method for improving the dimensional accuracy of single crystal high-temperature alloy castings. Background Technology

[0002] The development of aviation technology has placed higher demands on the performance of aero-engines, and the technological level of aero-engines is an important indicator of a country's scientific and technological level and industrial strength. The key to aero-engine development is improving thrust-to-weight ratio and fuel efficiency, and the performance of aero-engines largely depends on turbine inlet temperature. Single-crystal superalloys possess excellent high-temperature properties, including high creep strength and toughness, sufficient toughness, good resistance to thermal and mechanical fatigue, and good resistance to oxidation and hot corrosion. Therefore, single-crystal superalloys are currently the main materials for manufacturing advanced aero-engine and gas turbine blades. Single-crystal superalloy turbine blades are widely used in advanced military and civilian aero-engines.

[0003] With advancements in blade design technology, the internal cooling gas channels of blades are becoming increasingly complex, and the blade's overall dimensions and cross-sectional area are expanding. During the directional solidification process of blades, the high-temperature molten alloy can easily cause localized deformation in larger shell sizes. The larger the shell and the longer the directional solidification time, the greater the likelihood of shell deformation. Shell deformation leads to problems such as excessive blade wall thickness tolerance (i.e., increased blade wall thickness), excessive profile tolerance (i.e., blade deformation), and excessive blade weight (i.e., increased blade weight), which in turn increases the workload of subsequent blade polishing, grinding, and machining.

[0004] In the performance evaluation of single-crystal superalloy components, it is usually necessary to prepare single-crystal thin-walled specimens to simulate the thin-walled properties of single-crystal superalloys. After casting, the thin-walled working position of the single-crystal thin-walled specimen is required to be the casting surface, and it cannot be polished, ground or machined. Therefore, the dimensional accuracy requirements of the thin-walled working position are very high.

[0005] The invention patent with publication number CN111299511A discloses a method for preparing a single-crystal high-temperature alloy thin-walled casting. The method involves attaching wax paper to the surface of a ceramic support to form a wax model, resulting in a support-wax model assembly. The bottom edge of the wax paper coincides with the bottom edge of the ceramic support, and the shape and size of the wax paper are identical to the target single-crystal high-temperature alloy thin-walled casting. A crystal selector and amplifier assembly are fixed to the bottom of the support-wax model assembly to obtain an intermediate body. The amplifier in the crystal selector and amplifier assembly is connected to the bottom of the support-wax model assembly, and the crystal selector and amplifier are made of wax. The intermediate body is assembled onto a gating plate, coated with a slurry to form a shell, and dewaxed to obtain a mold. Molten single-crystal high-temperature alloy is poured into the mold to obtain the single-crystal high-temperature alloy thin-walled casting. This technical solution uses wax paper directly as the thin-walled part of the casting. Although it does not rely on a mold, the method of applying wax paper can prepare thin-walled samples with a thickness of 0.3-1mm. However, it cannot guarantee that the thin-walled casting will deform during the directional solidification process. It may need to be polished or ground afterward, which will reduce the dimensional accuracy of the thin-walled casting.

[0006] Chinese patent application CN114713775A discloses a method for preparing a large cylindrical titanium casting with an opening. First, a casting mold is made according to the shape and size of the cylindrical titanium casting. The outer shape and inner cavity of the casting mold are matched to the cylindrical titanium casting, and the inner cavity space of the casting mold corresponding to the opening edge of the cylindrical titanium casting is radially enlarged. Then, the casting mold is connected to the casting furnace to form a casting system, and multiple reinforcing ribs are set at the opening of the casting mold. Reinforcing ribs have internal runners connected to the casting system. The casting is then poured into the casting mold. After cooling, the casting mold is disassembled, and the thickened portion at the opening edge of the cylindrical titanium casting is machined to obtain the large cylindrical titanium casting with an opening. This technical solution involves setting reinforcing ribs at the opening of the casting mold, and the reinforcing ribs are connected to the casting. Disassembling the reinforcing ribs can cause deformation of the casting. Furthermore, the casting requires machining, which reduces the dimensional accuracy of the casting. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a wax model for improving the dimensional accuracy of single-crystal superalloy castings, comprising a base, spiral crystal selectors, a crystal puller, a single-crystal casting, a sprue, and a pouring cup. Four spiral crystal selectors are evenly arranged circumferentially near the edge of the base. Each spiral crystal selector is sequentially connected to the crystal puller, the single-crystal casting, and the sprue. The top of each of the four sprues is connected to a pouring cup. A vertical support column is positioned between two adjacent single-crystal castings, and the four vertical support columns are vertically fixed to the base. A grid wax sheet is suspended on each side of each single-crystal casting, and each grid wax sheet is fixedly connected to its adjacent vertical support column via a first and a second transverse support column. The shape of each grid wax sheet matches the shape of its corresponding single-crystal casting, and the distance between each grid wax sheet and its corresponding single-crystal casting is equal.

[0008] Preferably, the single crystal casting is a single crystal thin-walled sample or a single crystal hollow blade.

[0009] In any of the above embodiments, preferably, the two clamping sections of the single-crystal thin-walled sample are respectively connected to the crystal puller and the inclined sprue, and a grid wax sheet is suspended on each side of the thin-walled section of the single-crystal thin-walled sample. The shape of the grid wax sheet matches the shape of its corresponding thin-walled section, and the distance between the grid wax sheet and its corresponding thin-walled section is equal. The blade body and tenon extension section of the single-crystal hollow blade are respectively connected to the crystal puller and the inclined sprue, and a grid wax sheet is suspended on each side of the blade body. The shape of the grid wax sheet matches the shape of its corresponding blade body, and the distance between the grid wax sheet and its corresponding blade body is equal.

[0010] In any of the above embodiments, it is preferred that the grid wax sheet is composed of several grid-shaped structures combined together and integrally formed; the thickness of the vertical and horizontal grid rods of the grid wax sheet is 1-3mm and the width is 8-10mm; the grid on the grid wax sheet is square and the side length of its inner wall is 20mm.

[0011] Preferably, in any of the above embodiments, the distance between the grid wax sheet and its corresponding single-crystal casting is 3-5 mm. In this invention, according to the shape of the single-crystal casting, the shape of the grid wax sheet suspended on both sides of the single-crystal casting is matched with the shape of its corresponding single-crystal casting, so that after the grid wax sheets are suspended on both sides of the single-crystal casting, the distance between the grid wax sheet on each side and its corresponding single-crystal casting is equal. When the single-crystal casting is a single-crystal thin-walled sample, both sides of the thin-walled section of the single-crystal thin-walled sample are planes, so the grid wax sheet is also plane, and the distance between the plane of the thin-walled section and the plane of the grid wax sheet is equal; when the single-crystal casting is a single-crystal hollow blade, both sides of the blade body of the single-crystal hollow blade are curved surfaces, so the grid wax sheet is also curved surfaces, and the distance between the curved surface of the blade body and the curved surface of the grid wax sheet is equal.

[0012] In any of the above embodiments, it is preferred that one end of the first horizontal support column is connected to the center of the uppermost horizontal mesh rod of the grid wax sheet, and the other end is connected to the vertical support column; one end of the second horizontal support column is connected to the center of the lowermost horizontal mesh rod of the grid wax sheet, and the other end is connected to the vertical support column.

[0013] In any of the above embodiments, it is preferred that the angle between the first horizontal support column and the vertical support column is 85-88°, and the angle between the second horizontal support column and the vertical support column is 75-85°.

[0014] In this invention, the positional relationship between the first and second transverse support columns and the vertical support column is very important. Since the grid wax sheet does not contact the single crystal casting, the grid wax sheet needs to be removed through the first and second transverse support columns during dewaxing. The second transverse support column is particularly important, as most of the wax liquid after the grid wax sheet melts is removed through the second transverse support column.

[0015] In any of the above embodiments, it is preferred that the vertical support column is cylindrical with a diameter of 5-8 mm; the first horizontal support column and the second horizontal support column are both cylindrical with a diameter of 2-4 mm.

[0016] In any of the above embodiments, preferably, the chassis, spiral crystal selector, crystal puller, single crystal casting, sprue, pouring cup, vertical support column, first horizontal support column, second horizontal support column, and grid wax sheet are all made of wax; the chassis is disc-shaped with a diameter of 200-250mm; the crystal puller has a cone angle of 30-60°; the sprue is cylindrical with a diameter of 10-20mm and a length of 100-130mm, and the angle between the sprue and the top plane of the single crystal casting is 40-60°; the pouring cup is frustum-shaped.

[0017] The present invention also provides a method for improving the dimensional accuracy of single-crystal superalloy castings, using the wax model described in any of the above-mentioned methods for improving the dimensional accuracy of single-crystal superalloy castings, comprising the following steps in sequence:

[0018] Step 1: Press the chassis, spiral crystal selector, crystal cone, single crystal casting, sprue, pouring cup, vertical support column, first horizontal support column, second horizontal support column, and grid wax sheet using the wax pressing method according to the design requirements;

[0019] Step 2: Assemble the base, spiral crystal selector, crystal guide cone, single crystal casting, sprue, pouring cup, and vertical support column according to the designed wax model structure;

[0020] If the single crystal casting is a single crystal thin-walled sample, and both sides of its thin-walled section are flat, then a flat grid wax sheet is suspended on each side of the thin-walled section, and the distance between the grid wax sheet on both sides and its corresponding thin-walled section is equal. Then, the grid wax sheets on both sides are fixed to the adjacent vertical support column by the first transverse support column and the second transverse support column respectively.

[0021] If the single crystal casting is a single crystal hollow blade, and both sides of the blade body are curved, then a curved grid wax sheet is suspended on each side of the blade body, and the distance between the grid wax sheet on both sides and the corresponding blade body is equal. Then, the grid wax sheets on both sides are fixed to the adjacent vertical support column by the first horizontal support column and the second horizontal support column respectively.

[0022] Step 3: After the wax model assembly is completed, the ceramic shell is prepared using the investment casting method;

[0023] Step 4: After the ceramic shell is prepared, place the ceramic shell into a directional solidification furnace and cast it using the directional solidification method to obtain a single crystal high-temperature alloy casting with high-precision external dimensions.

[0024] In this invention, the shell of the mesh wax sheet is integrated with the shell of the single crystal casting. During the pouring and directional solidification processes, the mesh wax sheet acts as a reinforcing rib, preventing deformation of the shell of the single crystal casting and thus improving the dimensional accuracy of the single crystal casting. The wax pressing method, investment casting method, and directional solidification method used in this invention are traditional methods, and no special limitations are placed on the specific process parameters.

[0025] This invention relates to a wax model and method for improving the dimensional accuracy of single-crystal superalloy castings. A grid of wax sheets is suspended on both sides of the single-crystal casting. The wax sheets do not contact the casting and maintain a constant distance of 3-5 mm. After coating, the wax pattern is connected to the single-crystal casting shell, increasing its strength and reducing deformation during high-temperature casting and directional solidification. This improves the dimensional accuracy and yield of the single-crystal superalloy casting. The invention also creates reinforcing ribs on the surface of the single-crystal casting shell. Without significantly increasing the overall thickness, it does not alter the surface condition or roughness of the casting, improving wall thickness control accuracy and reducing subsequent polishing and thickness testing. Furthermore, it does not alter current automated coating processes and can be widely applied to the fabrication of larger single-crystal superalloy castings. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a preferred embodiment of a wax model for improving the dimensional accuracy of single-crystal superalloy castings according to the present invention;

[0027] Figure 2 for Figure 1 A schematic diagram of the structure of the grid wax sheet in the embodiment shown;

[0028] Figure 3 for Figure 1 Photograph of the single-crystal high-temperature alloy thin-walled sample casting prepared in the illustrated embodiment;

[0029] Figure 4 This is a schematic diagram of another preferred embodiment of a wax model for improving the dimensional accuracy of single-crystal superalloy castings according to the present invention;

[0030] Figure 5 for Figure 4 A schematic diagram of the structure of the single-crystal high-temperature alloy hollow blade casting prepared in the embodiment shown.

[0031] Explanation of annotations in the image:

[0032] 1-Base plate, 2-Spiral crystal selector, 3-Crystal guide cone, 4-Slanted sprue, 5-Pour cup, 6-Vertical support column, 7-First horizontal support column, 8-Second horizontal support column;

[0033] 9-Grid wax sheet, 91-Vertical grid pole, 92-Horizontal grid pole, 93-Grid;

[0034] 10 - Single crystal thin-walled sample; 101 - Clamping section; 102 - Thin-walled section;

[0035] 11-Single crystal hollow blade, 111-Blade body, 112-Tenon extension section. Detailed Implementation

[0036] To further understand the invention, the following detailed description of the invention will be provided in conjunction with specific embodiments.

[0037] Example 1:

[0038] like Figure 1 As shown, a preferred embodiment of the wax model for improving the dimensional accuracy of single-crystal high-temperature alloy castings according to the present invention includes a base 1, spiral crystal selectors 2, crystal puller cones 3, single-crystal thin-walled specimens 10, sprues 4, and pouring cups 5; four spiral crystal selectors 2 are evenly arranged circumferentially near the edge of the base 1, each spiral crystal selector 2 is sequentially connected to the crystal puller cone 3, the single-crystal thin-walled specimen 10, and the sprue 4, and the top of each of the four sprues 4 is connected to one of the pouring cups 5; adjacent single-crystal thin-walled specimens 10... A vertical support column 6 is set at the middle position of the base 1, and the four vertical support columns 6 are vertically fixed on the base 1; a grid wax sheet 9 is suspended on both sides of each single crystal thin-walled sample 10, and each grid wax sheet 9 is fixedly connected to its adjacent vertical support column 6 through a first horizontal support column 7 and a second horizontal support column 8; the shape of each grid wax sheet 9 matches the shape of its corresponding single crystal thin-walled sample 10, and the distance between each grid wax sheet 9 and its corresponding single crystal thin-walled sample 10 is equal.

[0039] The two clamping sections 101 of the single crystal thin-walled sample 10 are respectively connected to the crystal taper 3 and the inclined sprue 4. A grid wax sheet 9 is suspended on both sides of the thin-walled section 102 of the single crystal thin-walled sample 10. The shape of the grid wax sheet 9 matches the shape of its corresponding thin-walled section 102, and the distance between the grid wax sheet 9 and its corresponding thin-walled section 102 is equal to 4mm.

[0040] like Figure 2 As shown, the grid wax sheet 9 is composed of several grid-shaped structures combined together and integrally formed; the thickness of the vertical grid rods 91 and the horizontal grid rods 92 of the grid wax sheet 9 are both 2mm and the width is both 9mm; the grid 93 on the grid wax sheet 9 is square and the side length of its inner wall is 20mm.

[0041] One end of the first transverse support column 7 is connected to the center of the uppermost transverse mesh rod 92 of the grid wax sheet 9, and the other end is connected to the vertical support column 6; one end of the second transverse support column 8 is connected to the center of the lowermost transverse mesh rod 92 of the grid wax sheet 9, and the other end is connected to the vertical support column 6. The included angle β between the first transverse support column 7 and the vertical support column 6 is 86°, and the included angle γ between the second transverse support column 8 and the vertical support column 6 is 80°. The vertical support column is cylindrical with a diameter of 6mm; both the first transverse support column and the second transverse support column are cylindrical with a diameter of 3mm. In this embodiment, the positional relationship between the first and second transverse support columns and the vertical support column is very important. Since the grid wax sheet does not contact the single-crystal thin-walled sample, the grid wax sheet needs to be removed through the first and second transverse support columns during dewaxing. The second transverse support column is particularly important, as most of the melted wax from the grid wax sheet is removed through the second transverse support column.

[0042] The chassis, spiral crystal selector, crystal puller, single crystal casting, sprue, pouring cup, vertical support column, first horizontal support column, second horizontal support column, and grid wax sheet are all made of wax. The chassis is disc-shaped with a diameter of 220 mm. The cone angle α of the crystal puller is 45°. The sprue is cylindrical with a diameter of 15 mm and a length of 115 mm. The angle between the sprue and the top plane of the single crystal casting is 50°. The pouring cup is frustum-shaped.

[0043] This embodiment also provides a method for improving the dimensional accuracy of single-crystal superalloy castings, which uses the wax model described above for improving the dimensional accuracy of single-crystal superalloy castings and includes the following steps in sequence:

[0044] Step 1: Press the base plate, spiral crystal selector, crystal cone, single crystal thin-walled sample, inclined runner, pouring cup, vertical support column, first horizontal support column, second horizontal support column and grid wax sheet using the wax pressing method according to the design requirements;

[0045] Step 2: Assemble the base, spiral crystal selector, crystal puller, single crystal thin-walled sample, inclined sprue, pouring cup, and vertical support column according to the designed wax mold structure; both sides of the thin-walled section of the single crystal thin-walled sample are flat, and a flat grid wax sheet is suspended on each side of the thin-walled section, with the distance between the grid wax sheet on both sides and its corresponding thin-walled section being equal. Then, the grid wax sheets on both sides are fixed to the adjacent vertical support column through the first and second transverse support columns respectively.

[0046] Step 3: After the wax model assembly is completed, the ceramic shell is prepared using the investment casting method;

[0047] Step 4: After the ceramic shell is prepared, place the ceramic shell into a directional solidification furnace and cast it using the directional solidification method to obtain a single crystal high-temperature alloy thin-walled sample casting with high-precision external dimensions.

[0048] The wax pressing method, investment casting method, and directional solidification method used in this embodiment are traditional methods, and no special limitations are made on the specific process parameters.

[0049] Figure 3 The image shows a photograph of the single-crystal high-temperature alloy thin-walled sample casting prepared in this embodiment. The total length of the casting is 280 mm, the length of the thin-walled section is 120 mm, the width of the casting is 45 mm, the thickness of the clamping section is 12 mm, and the thickness of the thin-walled section is 2 mm. Three cross-sections L1, L2, and L3 were made on the thin-walled section of the casting, with L2 being the cross-section along the center of the thin-walled section. The distance between L1, L3, and L2 is 20 mm. Three longitudinal sections K1, K2, and K3 were made on the thin-walled section of the casting, with K2 being the longitudinal section along the center of the thin-walled section. The distance between K1, K3, and K2 is 10 mm. The wall thickness of the casting was tested using an industrial CT inspection device. Nine locations where the three cross-sections and three longitudinal sections intersect were used as wall thickness test points. The measured wall thickness deviation data are shown in Table 1.

[0050] Comparative test: In the wax model, no grid wax sheet is set, nor are vertical and horizontal support columns for supporting the grid wax sheet. Other structures are the same as in this embodiment. The process steps, process parameters, dimensions of the prepared single crystal high temperature alloy thin-walled sample casting, test points, test conditions, etc. are all the same as in this embodiment. The measured wall thickness deviation data are shown in Table 2.

[0051] Table 1. Wall thickness deviation data of the single-crystal superalloy thin-walled sample castings prepared in this embodiment.

[0052]

[0053] Table 2 shows the wall thickness deviation data of the single-crystal superalloy thin-walled sample castings prepared by comparative experiments.

[0054]

[0055] This embodiment describes a wax model and method for improving the dimensional accuracy of single-crystal superalloy castings. A grid of wax sheets is suspended on both sides of the single-crystal casting, maintaining a constant distance without contact with the casting. After coating, the wax sheet shell connects to the single-crystal casting shell, increasing its strength and reducing deformation during high-temperature casting and directional solidification. This improves the dimensional accuracy and yield of the single-crystal superalloy casting. Furthermore, this embodiment forms reinforcing ribs on the surface of the single-crystal casting shell. Without significantly increasing the overall thickness, it maintains the surface condition and roughness of the casting, improving wall thickness control accuracy and reducing subsequent polishing and wall thickness testing. It also retains the advantage of not altering current automated coating processes and can be widely applied to the fabrication of larger single-crystal superalloy castings.

[0056] Example 2:

[0057] like Figure 4 As shown, another preferred embodiment of the wax model for improving the dimensional accuracy of single-crystal high-temperature alloy castings according to the present invention includes a base 1, spiral crystal selectors 2, crystal puller cones 3, single-crystal hollow blades 11, sloping runners 4, and a pouring cup 5; four spiral crystal selectors 2 are evenly arranged circumferentially near the edge of the base 1, and each spiral crystal selector 2 is sequentially connected to the crystal puller cone 3, the single-crystal hollow blade 11, and the sloping runner 4, and the top of each of the four sloping runners 4 is connected to a pouring cup 5; adjacent single-crystal hollow blades 11... A vertical support column 6 is set in the middle of the base 1, and the four vertical support columns 6 are vertically fixed on the base 1; a grid wax sheet 9 is suspended on both sides of each single crystal hollow blade 11, and each grid wax sheet 9 is fixedly connected to its adjacent vertical support column 6 through a first horizontal support column 7 and a second horizontal support column 8; the shape of each grid wax sheet 9 matches the shape of its corresponding single crystal hollow blade 11, and the distance between each grid wax sheet 9 and its corresponding single crystal hollow blade 11 is equal.

[0058] The blade body 111 and tenon extension 112 of the single-crystal hollow blade 11 are respectively connected to the crystal taper 3 and the inclined sprue 4. A grid wax sheet 9 is suspended on each side of the blade body 111. The shape of the grid wax sheet 9 matches the shape of its corresponding blade body 111, and the distance between the grid wax sheet 9 and its corresponding blade body 111 is equal to 3mm.

[0059] The grid wax sheet 9 is composed of several grid-shaped structures combined together and is integrally formed; the thickness of the vertical grid rods 91 and the horizontal grid rods 92 of the grid wax sheet 9 are both 1mm and the width is both 8mm; the grid 93 on the grid wax sheet 9 is square and the side length of its inner wall is 20mm.

[0060] One end of the first transverse support column 7 is connected to the center of the uppermost transverse mesh rod 92 of the grid wax sheet 9, and the other end is connected to the vertical support column 6; one end of the second transverse support column 8 is connected to the center of the lowermost transverse mesh rod 92 of the grid wax sheet 9, and the other end is connected to the vertical support column 6. The included angle β between the first transverse support column 7 and the vertical support column 6 is 85°, and the included angle γ between the second transverse support column 8 and the vertical support column 6 is 75°. The vertical support column is cylindrical with a diameter of 5mm; both the first transverse support column and the second transverse support column are cylindrical with a diameter of 2mm. In this embodiment, the positional relationship between the first and second transverse support columns and the vertical support column is very important. Since the grid wax sheet does not contact the single-crystal thin-walled sample, the grid wax sheet needs to be removed through the first and second transverse support columns during dewaxing. The second transverse support column is particularly important, as most of the melted wax from the grid wax sheet is removed through the second transverse support column.

[0061] The chassis, spiral crystal selector, crystal puller, single crystal casting, sprue, pouring cup, vertical support column, first horizontal support column, second horizontal support column, and grid wax sheet are all made of wax. The chassis is disc-shaped with a diameter of 200 mm. The cone angle α of the crystal puller is 30°. The sprue is cylindrical with a diameter of 10 mm and a length of 100 mm. The angle between the sprue and the top plane of the single crystal casting is 40°. The pouring cup is frustum-shaped.

[0062] This embodiment also provides a method for improving the dimensional accuracy of single-crystal superalloy castings, which uses the wax model described above for improving the dimensional accuracy of single-crystal superalloy castings and includes the following steps in sequence:

[0063] Step 1: Press the chassis, spiral crystal selector, crystal cone, single crystal hollow blade, inclined sprue, pouring cup, vertical support column, first horizontal support column, second horizontal support column and grid wax sheet using the wax pressing method according to the design requirements;

[0064] Step 2: Assemble the base, spiral crystal selector, crystal puller, single-crystal hollow blade, inclined sprue, pouring cup, and vertical support column according to the designed wax model structure; the blade body of the single-crystal hollow blade has curved surfaces on both sides, so a curved grid wax sheet is suspended on each side of the blade body, and the distance between the grid wax sheet on both sides and the corresponding blade body is equal. Then, the grid wax sheets on both sides are fixed to the adjacent vertical support column through the first and second transverse support columns respectively.

[0065] Step 3: After the wax model assembly is completed, the ceramic shell is prepared using the investment casting method;

[0066] Step 4: After the ceramic shell is prepared, place the ceramic shell into a directional solidification furnace and cast it using the directional solidification method to obtain a single crystal high-temperature alloy hollow blade casting with high-precision external dimensions.

[0067] The wax pressing method, investment casting method, and directional solidification method used in this embodiment are traditional methods, and no special limitations are made on the specific process parameters.

[0068] Figure 5 This is a schematic diagram of the structure of the single-crystal high-temperature alloy hollow blade casting prepared in this embodiment. The casting has a relatively large overall size, with a height of 140mm, a width of 56mm, and a thickness of 36mm. The blade body includes the blade base and the blade back, both of which are curved surfaces. The profile measurement is a curve, that is, the intersection line of the cross section with the blade base and the blade back. Three cross sections are made on the blade body of the casting, from bottom to top: section 2-2, section 5-5, and section 8-8. The distance from section 2-2 to the bottom blade tip is 21mm, section 5-5 is 65mm, and section 8-8 is 86mm. The surface dimensions of the casting are tested using industrial CT inspection equipment. The six positions where sections 2-2, 5-5, and 8-8 intersect with the blade base and blade back are used as surface dimension test points. The measured surface dimension deviation data are shown in Table 3.

[0069] Comparative test: In the wax model, no grid wax sheet is set, nor are vertical and horizontal support columns for supporting the grid wax sheet. Other structures are the same as in this embodiment. The process steps, process parameters, dimensions of the prepared single crystal high temperature alloy hollow blade casting, test points, test conditions, etc. are all the same as in this embodiment. The measured surface dimension deviation data are shown in Table 4.

[0070] Table 3. Dimensional deviation data of the single-crystal high-temperature alloy hollow blade casting prepared in this embodiment.

[0071]

[0072] Table 4 shows the dimensional deviation data of the single-crystal high-temperature alloy hollow blade castings prepared by comparative experiments.

[0073]

[0074] This embodiment describes a wax model and method for improving the dimensional accuracy of single-crystal superalloy castings. A grid of wax sheets is suspended on both sides of the single-crystal casting, maintaining a constant distance without contact with the casting. After coating, the wax sheet shell connects to the single-crystal casting shell, increasing its strength and reducing deformation during high-temperature casting and directional solidification. This improves the dimensional accuracy and yield of the single-crystal superalloy casting. Furthermore, this embodiment forms reinforcing ribs on the surface of the single-crystal casting shell. Without significantly increasing the overall thickness, it maintains the surface condition and roughness of the casting, improving wall thickness control accuracy and reducing subsequent polishing and wall thickness testing. It also retains the advantage of not altering current automated coating processes and can be widely applied to the fabrication of larger single-crystal superalloy castings.

[0075] Example 3:

[0076] Another preferred embodiment of the wax model and method for improving the dimensional accuracy of single-crystal high-temperature alloy castings according to the present invention is basically the same as that of Embodiment 2 in terms of wax model structure, connection relationship between various components, process steps, equipment used, technical principle and beneficial effects, except that:

[0077] The blade body and tenon extension of the single-crystal hollow blade are connected to the crystal taper and the sprue, respectively. A grid wax sheet is suspended on each side of the blade body. The shape of the grid wax sheet matches the shape of the corresponding blade body, and the distance between the grid wax sheet and the corresponding blade body is equal at 5mm. The vertical and horizontal grid bars of the grid wax sheet are both 3mm thick and 10mm wide. The grid on the grid wax sheet is square, and the side length of its inner wall is 20mm.

[0078] The angle β between the first horizontal support column and the vertical support column is 88°, and the angle γ between the second horizontal support column and the vertical support column is 85°. The vertical support column is cylindrical with a diameter of 8mm; both the first and second horizontal support columns are cylindrical with a diameter of 4mm.

[0079] The base is disc-shaped with a diameter of 250 mm; the cone angle α of the crystal-leading cone is 60°; the sprue is cylindrical with a diameter of 20 mm and a length of 130 mm, and the angle between the sprue and the top plane of the single crystal casting is 60°; the pouring cup is frustum-shaped.

[0080] Special Note: The technical solution of this invention involves numerous parameters, and the synergistic effects between these parameters must be comprehensively considered to achieve the beneficial effects and significant progress of this invention. Furthermore, the value ranges of each parameter in the technical solution were obtained through extensive experimentation. For each parameter and the combinations thereof, the inventors have recorded a large amount of experimental data; however, due to space limitations, the specific experimental data is not disclosed here.

[0081] Those skilled in the art will readily understand that the wax model and method for improving the dimensional accuracy of single-crystal high-temperature alloy castings of the present invention include any combination of the inventive description and specific embodiments described in the above specification and the parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wax model for improving the dimensional accuracy of single-crystal superalloy castings, characterized in that: The system includes a chassis, spiral crystal selectors, a crystal puller, a single crystal casting, a sprue, and a pouring cup. Four spiral crystal selectors are evenly arranged circumferentially near the edge of the chassis. Each spiral crystal selector is sequentially connected to the crystal puller, the single crystal casting, and the sprue. The top of each of the four sprues is connected to a pouring cup. A vertical support column is positioned between two adjacent single crystal castings, and the four vertical support columns are vertically fixed to the chassis. A grid wax sheet is suspended on each side of each single crystal casting. Each grid wax sheet is fixedly connected to its adjacent vertical support column via a first and a second horizontal support column. The shape of each grid wax sheet matches the shape of its corresponding single crystal casting, and the distance between each grid wax sheet and its corresponding single crystal casting is equal. One end of the first horizontal support column is connected to the center of the uppermost horizontal mesh rod of the grid wax sheet, and the other end is connected to the vertical support column; one end of the second horizontal support column is connected to the center of the lowermost horizontal mesh rod of the grid wax sheet, and the other end is connected to the vertical support column. The angle between the first horizontal support column and the vertical support column is 85-88°, and the angle between the second horizontal support column and the vertical support column is 75-85°.

2. The wax model for improving the dimensional accuracy of single-crystal high-temperature alloy castings according to claim 1, characterized in that: The single-crystal casting is a single-crystal thin-walled sample or a single-crystal hollow blade.

3. The wax model for improving the dimensional accuracy of single-crystal high-temperature alloy castings according to claim 2, characterized in that: The two clamping sections of the single-crystal thin-walled sample are respectively connected to the crystal puller and the inclined sprue. A grid wax sheet is suspended on each side of the thin-walled section of the single-crystal thin-walled sample. The shape of the grid wax sheet matches the shape of its corresponding thin-walled section, and the distance between the grid wax sheet and its corresponding thin-walled section is equal. The blade body and tenon extension section of the single-crystal hollow blade are respectively connected to the crystal puller and the inclined sprue. A grid wax sheet is suspended on each side of the blade body. The shape of the grid wax sheet matches the shape of its corresponding blade body, and the distance between the grid wax sheet and its corresponding blade body is equal.

4. The wax model for improving the dimensional accuracy of single-crystal high-temperature alloy castings according to claim 3, characterized in that: The grid wax sheet is composed of several grid-shaped structures combined together and is integrally formed; the thickness of the vertical and horizontal grid bars of the grid wax sheet is 1-3mm and the width is 8-10mm; the grid on the grid wax sheet is square and the side length of its inner wall is 20mm.

5. The wax model for improving the dimensional accuracy of single-crystal high-temperature alloy castings according to claim 4, characterized in that: The distance between the grid wax sheet and its corresponding single crystal casting is 3-5 mm.

6. The wax model for improving the dimensional accuracy of single-crystal high-temperature alloy castings according to claim 5, characterized in that: The vertical support column is cylindrical with a diameter of 5-8mm; the first horizontal support column and the second horizontal support column are both cylindrical with a diameter of 2-4mm.

7. The wax model for improving the dimensional accuracy of single-crystal high-temperature alloy castings according to claim 6, characterized in that: The base, spiral crystal selector, crystal guide cone, single crystal casting, sprue, pouring cup, vertical support column, first horizontal support column, second horizontal support column, and grid wax sheet are all made of wax. The base is disc-shaped with a diameter of 200-250mm. The crystal guide cone has a cone angle of 30-60°. The sprue is cylindrical with a diameter of 10-20mm and a length of 100-130mm. The angle between the sprue and the top plane of the single crystal casting is 40-60°. The pouring cup is frustum-shaped.

8. A method for improving the dimensional accuracy of single-crystal superalloy castings, characterized in that: The wax model used to improve the dimensional accuracy of single-crystal high-temperature alloy castings according to any one of claims 1-7 includes the following steps in sequence. Step 1: Press the chassis, spiral crystal selector, crystal cone, single crystal casting, sprue, pouring cup, vertical support column, first horizontal support column, second horizontal support column, and grid wax sheet using the wax pressing method according to the design requirements; Step 2: Assemble the base, spiral crystal selector, crystal guide cone, single crystal casting, sprue, pouring cup, and vertical support column according to the designed wax model structure; If the single crystal casting is a single crystal thin-walled sample, and both sides of its thin-walled section are flat, then a flat grid wax sheet is suspended on each side of the thin-walled section, and the distance between the grid wax sheet on both sides and its corresponding thin-walled section is equal. Then, the grid wax sheets on both sides are fixed to the adjacent vertical support column by the first transverse support column and the second transverse support column respectively. If the single crystal casting is a single crystal hollow blade, and both sides of the blade body are curved, then a curved grid wax sheet is suspended on each side of the blade body, and the distance between the grid wax sheet on both sides and the corresponding blade body is equal. Then, the grid wax sheets on both sides are fixed to the adjacent vertical support column by the first horizontal support column and the second horizontal support column respectively. Step 3: After the wax model assembly is completed, the ceramic shell is prepared using the investment casting method; Step 4: After the ceramic shell is prepared, place the ceramic shell into a directional solidification furnace and cast it using the directional solidification method to obtain a single crystal high-temperature alloy casting with high-precision external dimensions.

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