Gyro house investment casting method for aviation

Abstract

The application refers to a kind of aviation gyro house investment casting method, comprising: raw material wax is injected into mould to make wax mould;Wax mould is soaked in surface layer slurry to obtain first wax mould;First wax mould is soaked in first transition layer slurry to obtain second wax mould;Second wax mould is soaked in second transition layer slurry and uses moles of sand to hang sand on second wax mould, dry the second wax mould after hanging sand, obtain third wax mould;Third wax mould is soaked in back layer slurry and dried to obtain fourth wax mould;Fourth wax mould is soaked in sealing slurry and dried to obtain fifth wax mould;Fifth wax mould is dewaxed to obtain shell and calcine.The application refers to a kind of aviation gyro house investment casting method, the smelting and casting method is improved by the composition of wax mould and slurry, and the improvement of mould design and wax assembly mode, and the corresponding shell process of wax, improve product quality, shorten production process, reduce production cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engines, and particularly relates to a lost foam casting method for an aero gyroscope house. BACKGROUND

[0002] The aero gyroscope house is a device with an important role in the field of aviation. It provides a stable installation environment for the gyroscope and protects the gyroscope from external environmental influences such as vibration, impact, temperature change, etc. The aero gyroscope house usually needs to meet the requirements of high precision to ensure that the gyroscope can accurately measure the attitude and heading of the aircraft. In addition, since the gyroscope plays a crucial role in flight safety, the aero gyroscope house needs to have high reliability

[0003] Therefore, the surface and internal quality of the aero gyroscope house product are required to be high. During the casting process, the shrinkage of different wall thickness positions is different due to the influence of the metal liquid shrinkage, which is not easy to control, resulting in an increase in product size deviation. In order to ensure the size and shape of the product, three times of sizing are required. The strength of the product is high, the sizing pressure cannot be controlled, and cracking phenomenon occurs at local positions of the product, which needs to be welded and repaired subsequently, the production process is complicated, the production cost is increased, and the production cycle is prolonged. In addition, due to the uneven wall thickness of the casting, shrinkage and porosity defects are easily generated at the position with large wall thickness during the casting process, which reduces the yield of the product. SUMMARY

[0004] (I) Technical problems to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present application provides a lost foam casting method for an aero gyroscope house, which solves the technical problems that the production of the gyroscope house may cause cracking phenomenon at local positions of the product, subsequent welding and repair, and complicated production process.

[0006] (II) Technical solutions

[0007] In order to achieve the above-mentioned purposes, the main technical solutions adopted by the present application include:

[0008] The embodiment of the present application provides a lost foam casting method for an aero gyroscope house, and the method comprises the following steps:

[0009] Step S1: injecting raw material wax into a mold to prepare a wax mold;

[0010] Step S2: dipping the wax mold into the face layer slurry, the face layer slurry is prepared with the following ingredients: silica sol: lubricant: zirconium powder: defoaming agent = 0.9-1.1: 2.3-2.5: 3.5-3.7: 1.9-2.1, the viscosity of the face layer slurry is controlled to be 41-47s, the wax mold is coated with 130-150 mesh zirconium sand, the coated wax mold is dried, the drying time is controlled to be 6-8h, and a first wax mold is obtained;

[0011] Step S3: dipping the first wax mold into the first transition layer slurry, the first transition layer slurry is prepared with the following ingredients: silica sol: zirconium powder = 0.9-1.1: 2.3-2.5, the viscosity of the first transition layer slurry is controlled to be 10-12s, the first wax mold is coated with 25-50 mesh mullite sand, the coated first wax mold is dried, the drying time is controlled to be 10-16h, and a second wax mold is obtained;

[0012] Step S4: dipping the second wax mold into the second transition layer slurry, the second transition layer slurry is prepared with the following ingredients: silica sol: mullite powder: zirconium powder = 0.9-1.1: 0.9-1.1: 1.7-1.9, the viscosity of the second transition layer slurry is controlled to be 11-17s, the second wax mold is coated with 25-50 mesh mullite sand, the coated second wax mold is dried, the drying time is controlled to be 16-24h, and a third wax mold is obtained;

[0013] Step S5: dipping the third wax mold into the back layer slurry, the back layer slurry is prepared with the following ingredients: silica sol: mullite powder = 0.9-1.1: 1.4-16, the viscosity of the back layer slurry is controlled to be 11-17s, the third wax mold is coated with 16-30 mesh mullite sand, the coated third wax mold is dried, the drying time is controlled to be 16-24h, and a fourth wax mold is obtained;

[0014] Step S6: dipping the fourth wax mold into the sealing slurry, the sealing slurry is prepared with the following ingredients: silica sol: mullite powder = 0.9-1.1: 0.9-1.1, the viscosity of the sealing slurry is controlled to be 8-12s, the fourth wax mold is dried, the drying time is controlled to be 16-24h, and a fifth wax mold is obtained;

[0015] Step S7: dewaxing the fifth wax mold to obtain a shell;

[0016] Step S8: firing the shell.

[0017] Preferably, the method further comprises:

[0018] Step S9: casting: pouring a metal liquid into the fired shell, the time from the completion of firing to the start of pouring is controlled to be 10-20s, the pouring temperature is controlled to be 1650-1670℃, and the pouring time is controlled to be 8-12s.

[0019] Preferably, the method further comprises:

[0020] Step S10: After the metal liquid is cast in the shell, insulating agent is scattered at the opening of the shell, and the shell is placed in a closed environment.

[0021] Preferably, the method further comprises:

[0022] Step S11: The cast shell is subjected to shock and shell cleaning, and the shock and shell cleaning time is controlled to be 1-2 min to obtain the casting.

[0023] Preferably, step S1 in the method comprises:

[0024] In the case of injecting raw wax into the mold, the wax injection temperature is controlled to be 54-58℃, the wax injection pressure is controlled to be 2-3 MPa, the wax injection time is controlled to be 25-35 s, and the wax mold is placed for more than or equal to 4 h after the wax mold is completed.

[0025] Preferably, step S1 in the method comprises:

[0026] The wax mold is placed in a cleaning agent for cleaning, and the cleaning agent is neutral.

[0027] Preferably, step S1 in the method comprises:

[0028] A plurality of wax molds are cast, and the plurality of wax molds are fixedly connected with the raw wax as the shaft.

[0029] Preferably, step S7 in the method comprises:

[0030] The dewaxing temperature is controlled to be 175-185℃, the dewaxing pressure is controlled to be 0.75-1.0 MPa, and the dewaxing time is controlled to be 15-20 min.

[0031] Preferably, step S8 in the method comprises:

[0032] The baking temperature of the shell is controlled to be 1080-1120℃, the baking time is controlled to be 40-50 min, and then the heating is stopped, and the shell is completed baking when the temperature drops to 820-830℃.

[0033] Preferably, step S5 is repeated 1-3 times.

[0034] (Three) beneficial effects

[0035] The beneficial effects of the present application are: the present application refers to a gyro house for aviation investment casting method, the method comprises the following steps: injecting raw material wax into the mold to make a wax mold; soaking the wax mold in the surface layer slurry to obtain a first wax mold; soaking the first wax mold in the first transition layer slurry to obtain a second wax mold; soaking the second wax mold in the second transition layer slurry and using moissanite sand to hang sand on the second wax mold, drying the second wax mold after hanging sand to obtain a third wax mold; soaking the third wax mold in the back layer slurry, hanging sand and drying to obtain a fourth wax mold; soaking the fourth wax mold in the sealing slurry and drying to obtain a fifth wax mold; carrying out dewaxing treatment on the fifth wax mold to obtain a shell and baking. The present application refers to a gyro house for aviation investment casting method. The melting and casting method improves the product quality, shortens the production process and reduces the production cost by improving the composition of the wax mold, the first transition layer slurry, the second transition layer slurry, the back layer slurry and the sealing slurry, and improving the mold design and the assembly mode of the wax part, and the corresponding shell preparation process of the wax part. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A schematic flow chart of a gyro house for aviation investment casting method of the present application;

[0037] Figure 2 A nozzle design schematic diagram in example 1 of a gyro house for aviation investment casting method of the present application;

[0038] Figure 3 A wax part assembly mode schematic diagram in example 1 of a gyro house for aviation investment casting method of the present application;

[0039] Figure 4 A nozzle design schematic diagram in example 2 of a gyro house for aviation investment casting method of the present application;

[0040] Figure 5 A wax part assembly mode schematic diagram in example 2 of a gyro house for aviation investment casting method of the present application. DETAILED DESCRIPTION

[0041] In order to better explain the present application, so as to be understood, the present application is described in detail in combination with the drawings through specific embodiments.

[0042] When expressing a range, a concentration, or other value or parameter of an amount, either as a specific number value or as a number value within a range, preferably a range, or a series of upper preferred values and lower preferred values, it is to be understood that the disclosure specifically encompasses all ranges formed from any of the upper or lower values of any of the ranges or preferred values, whether or not the range is expressly disclosed. For example, where a range "1-5" is disclosed, the disclosure is to be interpreted to include ranges such as "1-4," "1-3," "1-2," "1-2 and 4-5," "1-3 and 5," etc. When numerical ranges are disclosed, unless otherwise stated, the range is intended to include both the upper and lower values and all intervening values of the range, as well as the integers within the range.

[0043] In these embodiments, unless otherwise indicated, the parts and percentages are by mass. "Parts by mass" refers to a basic unit of measurement that represents the proportional relationship of the mass of multiple components, 1 part can represent any unit mass, such as 1 g, 3.527 g, etc. If we say that the mass of component A is a parts, and the mass of component B is b parts, it means that the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK, and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike parts by mass, the sum of the parts by mass of all components is not limited to 100 parts. "And / or" is used to indicate that one or both of the described situations can occur, for example, A and / or B includes (A and B) and (A or B).

[0044] For a better understanding of the above technical solutions, exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer, more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0045] Reference Figure 1 In the present technical solution, the above method comprises the following steps:

[0046] Step S1: injecting raw wax into a mold to make a wax mold;

[0047] It should be noted that, with reference to Figures 2 to 5 The above raw wax is injected into a mold as shown in the figure to make a wax mold. Exemplarily, the above wax mold can have the shape shown in Figure 2 and Figure 4 .

[0048] Exemplarily, after the injection of the wax mold is completed, the wax mold is taken out of the mold and can be placed in cooling water or a storage tray for cooling.

[0049] Step S2: dipping the wax mold into the surface layer slurry, the surface layer slurry is prepared according to the following ingredients and proportions: silica sol: lubricant: 350 mesh zirconium powder: defoaming agent = 0.9-1.1: 2.3-2.5: 3.5-3.7: 1.9-2.1, the viscosity of the surface layer slurry is controlled to be 41-47s, 130-150 mesh zirconium sand is used to coat the wax mold, and the coated wax mold is dried for 6-8h to obtain a first wax mold;

[0050] It should be noted that the wax mold is dipped into the surface layer slurry prepared according to the above ingredients and proportions, and the surface layer slurry should be stirred uniformly before coating the surface layer slurry to reduce the precipitation of materials in the surface layer slurry as much as possible, so that the surface layer slurry can well fill and wet the wax mold.

[0051] For example, when coating the surface layer slurry, the wax mold can be soaked in the surface layer slurry and shaken left and right and up and down, so that the surface layer slurry can well wet the wax mold and uniformly cover the surface of the wax mold. After the coating is completed, sanding is performed, 130-150 mesh zirconium sand is used to coat the wax mold, and the coated wax mold is dried for 6-8h to obtain a first wax mold.

[0052] It should be noted that the above-mentioned mullite sand is a refractory sand material, and the above-mentioned first wax mold is dried and hardened under specific temperature and humidity conditions to form a dense refractory coating on the surface of the wax mold.

[0053] Step S3: dipping the first wax mold into the first transition layer slurry, the first transition layer slurry is prepared according to the following ingredients: silica sol: 325 mesh zirconium powder = 0.9-1.1: 2.3-2.5, the viscosity of the first transition layer slurry is controlled to be 10-12s, 25-50 mesh mullite sand is used to coat the first wax mold, and the coated first wax mold is dried for 10-16h to obtain a second wax mold;

[0054] It should be noted that the first wax mold is dipped into the first transition layer slurry prepared according to the above ingredients and proportions, and the first transition layer slurry should be stirred uniformly before coating the first transition layer slurry to reduce the precipitation of materials in the first transition layer slurry as much as possible, so that the first transition layer slurry can well fill and wet the wax mold.

[0055] For example, when coating the first transition layer slurry, the first wax mold can be soaked in the first transition layer slurry and shaken left and right and up and down, so that the first transition layer slurry can well wet the wax mold and uniformly cover the surface of the first wax mold. After the coating is completed, sanding is performed, 25-50 mesh mullite sand is used to coat the first wax mold, and the coated first wax mold is dried for 10-16h to obtain a second wax mold.

[0056] Step S4: Soaking the second wax mold into a second transition layer slurry, the second transition layer slurry is compounded by silica sol: mullite powder: 325 mesh zirconium powder = 0.9-1.1: 0.9-1.1: 1.7-1.9, the viscosity of the second transition layer slurry is controlled to be 11s-17s, the second wax mold is coated with 25-50 mesh mullite sand, and the coated second wax mold is dried, the drying time is controlled to be 16-24 hours, and a third wax mold is obtained;

[0057] Step S5: Soaking the third wax mold into a back layer slurry, the back layer slurry is compounded by silica sol: 200 mesh mullite powder = 0.9-1.1: 1.4-16, the viscosity of the back layer slurry is controlled to be 11s-17s, the third wax mold is coated with 16-30 mesh mullite sand, and the coated third wax mold is dried, the drying time is controlled to be 16-24 hours, and a fourth wax mold is obtained;

[0058] Step S6: Soaking the fourth wax mold into a sealing slurry, the sealing slurry is compounded by silica sol: 200 mesh mullite powder = 0.9-1.1: 0.9-1.1, the viscosity of the sealing slurry is controlled to be 8s-12s, and the fourth wax mold is dried, the drying time is controlled to be 16-24 hours, and a fifth wax mold is obtained;

[0059] Step S7: The fifth wax mold is subjected to a dewaxing treatment, and a shell is obtained.

[0060] It should be noted that the dewaxing treatment of the fifth wax mold is exemplarily heating the fifth wax mold to melt the raw material wax in the fifth wax mold, and then pouring out the wax liquid of the raw material wax.

[0061] Step S8: The shell is fired.

[0062] Exemplarily, referring to Figure 3 or Figure 5 The pouring gate is left, and after the shell is fired at high temperature, pouring can be performed, and a cast part is produced in this way.

[0063] In the technical solution, the method further comprises:

[0064] Step S9: Pouring: pouring a metal liquid into the shell after firing, the time from the completion of firing to the start of pouring is controlled to be 10-20 seconds, the pouring temperature is controlled to be 1650-1670°C, and the pouring time is controlled to be 8-12 seconds.

[0065] It should be noted that in the prior art, in the production Figure 2 or Figure 3The wall thickness of the gyroscope house casting shown in the figure is uneven, and shrinkage defects are easily generated in the wall thickness during the casting process, thereby reducing the yield of the product. By setting the pouring time, the operation time and the temperature range, the shrinkage defects of the wall thickness can be reduced, and the quality and yield of the casting are improved.

[0066] The method further comprises the following steps in the technical solution:

[0067] Step S10: After the metal liquid is poured into the shell, a heat preservation agent is scattered at the opening of the shell, and the shell is placed in a closed environment.

[0068] It should be noted that the opening of the shell is the pouring gate of the metal liquid.

[0069] After the shell is filled with the metal liquid, the heat preservation agent can be scattered at the pouring gate to prevent the temperature of the pouring gate from dropping sharply after the pouring is completed, thereby reducing the fluidity of the liquid in the shell.

[0070] After the pouring is completed, the shell can be placed on the bricks for 8-24 hours to prevent air leakage.

[0071] The method further comprises the following steps in the technical solution:

[0072] Step S11: The shell after pouring is shaken to remove the shell, and the shaking time is controlled to be 1-2 minutes to obtain the casting.

[0073] The shell after pouring is shaken to remove the shell to obtain the casting, and a shell shaking machine can be used to shake the shell, and the shaking time is controlled to be 1-2 minutes. The shaking time can ensure that the shell is completely separated from the casting, and the surface of the casting will not crack and be damaged.

[0074] In the technical solution, step S1 of the method comprises the following steps:

[0075] In the case of injecting raw wax into the mold, the wax injection temperature is controlled to be 54-58℃, the wax injection pressure is controlled to be 2-3MPa, the wax injection time is controlled to be 25-35s, and the placement time after the wax mold is completed is greater than or equal to 4h.

[0076] It should be noted that in the case of using the mold to prepare the wax mold, it can be checked whether the wax injection port of the mold is aligned with the wax injection nozzle of the machine, and whether the opening and closing of the mold is smooth.

[0077] In the technical solution, step S1 of the method comprises the following steps:

[0078] The wax mold is placed in a cleaning agent for cleaning, and the cleaning agent is neutral.

[0079] It should be noted that the wax film cleaner can act on the surface of the wax mold, so that the oil film layer such as the release agent adsorbed on the surface of the wax mold and affecting the hanging slurry is dissolved and removed.

[0080] In the technical solution, the step S1 in the method comprises:

[0081] A plurality of the wax molds are cast, and the plurality of the wax molds are fixedly connected with the raw material wax as the shaft.

[0082] Exemplarily, referring to Figures 2 to 5 A plurality of the wax molds can be cast, and the plurality of the wax molds are fixedly connected with the raw material wax as the shaft according to Figure 2 or Figure 4 The wax molds are grouped in the manner, the plurality of the wax molds are fixedly connected with the raw material wax as the shaft, and the plurality of the wax molds are reserved in the shape according to Figure 3 or Figure 5 at least one opening for pouring and / or discharging.

[0083] Exemplarily, the size of the raw material wax as the shaft can be 40 mm*60 mm*150 mm.

[0084] In the technical solution, the step S7 in the method comprises:

[0085] The dewaxing temperature is controlled to be 175-185℃, the pressure is controlled to be 0.75-1.0 MPa, and the dewaxing time is controlled to be 15-20 min.

[0086] It should be noted that the temperature and the pressure are controlled to be in the above range during the dewaxing process, so that the wax liquid can flow out smoothly and continuously, and the amount of the lost wax mold in the shell is small after the dewaxing is completed.

[0087] In the technical solution, the step S8 in the method comprises:

[0088] The baking temperature of the shell is controlled to be 1080-1120℃, the baking time is controlled to be 40-50 min, then the heating is stopped, and the shell is completed baking when the temperature is reduced to 820-830℃.

[0089] In the technical solution, the step S5 is repeated 1-3 times.

[0090] Example 1:

[0091] First, the wax mold is made, the raw material wax is injected into the mold, the wax injection temperature is controlled to be 56±2℃, the wax injection pressure is controlled to be 2.5±0.5 MPa, the wax injection time is controlled to be 30±5 s, the wax mold is taken out from the mold after the wax mold injection is completed, and the wax mold is cooled, and the wax mold is placed for more than 4 h after the wax mold is made.

[0092] In Example 1, a plurality of the above wax molds were cast, and the wax molds were assembled in the manner of Figure 2 The plurality of the above wax molds were fixedly connected with the above raw wax as the shaft, the wax rod with the raw wax as the shaft could have a size of 40 mm*60 mm*150 mm, and the wax piece assembly manner adopted 4-face assembly. Figure 3 The water inlet of the wax mold was designed, as shown in Figure 3 Two water inlets were designed.

[0093] The assembled wax mold was placed in a cleaning agent for cleaning, the wax mold cleaning agent was neutral,

[0094] The number of shell layers was 6.5 layers.

[0095] The surface layer: the slurry ingredients were silica sol: lubricant: 350-mesh zirconium powder: defoaming agent = 1:2.4:3.6:2, and the viscosity was 44±3 s; the sand coating: 130-mesh zirconium sand; the drying time: 6-8 h.

[0096] The transition layer: the slurry ingredients and the ratio of the transition layer were silica sol: 325-mesh zirconium powder = 1:2.4, the slurry viscosity was 11±1 s; the sand coating treatment: 25-50-mesh mullite sand; the drying time: 10-16 h.

[0097] The third layer: the slurry ingredients were silica sol: mullite powder: 325-mesh zirconium powder = 1:1:1.8, the viscosity was 14±3 s; the sand coating treatment: 25-50-mesh mullite sand; the drying time: 16-24 h.

[0098] The back layer (4th-6th layers): the slurry ingredients of each layer were silica sol: 200-mesh mullite powder = 1:1.5, the viscosity was 14±3 s; the sand coating treatment of each layer: 16-30-mesh mullite sand; each layer was dried for 16-24 h after the sand coating treatment.

[0099] The sealing slurry: the slurry ingredients were silica sol: 200-mesh mullite powder = 1:1, the slurry viscosity was 10±2 s, and the mold was dried for 16-24 h after the slurry coating.

[0100] Dewaxing: after the shell was made, dewaxing treatment was performed, the dewaxing temperature was 175-185°C, the dewaxing pressure was 0.75-1.0 MPa, and the dewaxing time was 15-20 min.

[0101] Casting

[0102] The shell is baked at 1100±20℃ for 45±5min to ensure that the shell is baked thoroughly, and then the heating is stopped and the temperature is maintained until the temperature drops to 820-830℃, and the shell is discharged; the shell is immediately cast after being discharged, and the time from the shell being discharged to the casting being started is controlled within 10-20s to reduce the loss of the temperature of the shell; the casting temperature is 1660℃±10℃, and the casting time is ensured within 10±2s. After the shell is filled with the molten metal, the pouring gate is sprinkled with a heat preservative to prevent the temperature of the pouring gate from dropping suddenly and to reduce the flowability of the liquid in the shell; the shell after casting is placed under a turning handle, and the entire shell is buckled for 8-24h, and the buckling is tight to prevent air leakage.

[0103] Shell cleaning: shell vibrating machine, shell vibrating time 1-2min; the shell vibrating time can ensure that the shell is completely separated from the casting and that the surface of the casting will not crack and be damaged.

[0104] After the shell is cleaned, the casting is subjected to water gate grinding treatment to grind off the excess water gate and runner.

[0105] Example 2

[0106] The water gate design of the wax mold in this scheme is shown in Figure 4 This scheme designs one water gate, and the wax assembly mode of this scheme adopts two-face assembly.

[0107] Wax mold making

[0108] The raw materials for making the wax mold are medium-temperature wax, the wax injection temperature is 56±2℃, the wax injection pressure is 2.5±0.5MPa, the wax injection time is 30±5s, and the wax piece is placed for more than 4h after being made.

[0109] The wax piece is assembled in the manner Figure 5 The size of the wax rod is 40mm*60mm*150mm.

[0110] The assembled wax mold is cleaned in a cleaning agent, and the wax mold cleaning agent is neutral.

[0111] Shell making

[0112] Different from example 1, the number of layers in the shell making process in this scheme is 5.5 layers.

[0113] Surface layer: the slurry ingredients are silica sol: lubricant: 350-mesh zirconium powder: defoaming agent = 1:2.4:3.6:2, and the viscosity is 44±3s; sanding: 130-mesh zirconium sand; drying time: 6-8h.

[0114] Transition layer: the slurry ingredients and the ratio of the transition layer are silica sol: 325-mesh zirconium powder = 1:2.4, and the slurry viscosity is 11±1s; sanding treatment: 25-50-mesh mullite sand; drying time: 10-16h.

[0115] Third layer: slurry ingredients silica sol: mullite powder: 325 mesh zirconium powder = 1:1:1.8, viscosity 14±3s; sand coating treatment: 25-50 mesh mullite sand; drying time 16-24h.

[0116] Back layer (4th-5th layer): slurry ingredients silica sol: 200 mesh mullite powder = 1:1.5, viscosity 14±3s; sand coating treatment: 16-30 mesh mullite sand; drying time 16-24h after sand coating treatment.

[0117] Sealing slurry: slurry ingredients silica sol: 200 mesh mullite powder = 1:1, slurry viscosity 10±2s, drying time 16-24h after slurry coating.

[0118] Dewaxing: dewaxing temperature 175-185℃, dewaxing pressure 0.75-1.0MPa, dewaxing time 15-20min.

[0119] Casting

[0120] Firing: firing temperature 1100±20℃, firing time 45±5min, ensuring complete firing of the shell, then stopping heating and waiting until the temperature drops to 820-830℃, then taking the shell out of the furnace; immediately after taking the shell out of the furnace, casting is performed, the time from taking the shell out of the furnace to starting casting is controlled within 10-20s to reduce temperature loss of the shell; casting temperature 1660℃±10℃, casting time is ensured within 10±2s. After the shell is filled with liquid metal, a heat preservation agent is applied to the sprue to prevent sudden temperature drop and reduce the flowability of the liquid in the shell; the bottom of the shell is padded with bricks after casting, and the entire shell is buckled for 8-24h, ensuring airtight buckling to prevent air leakage and oxidation.

[0121] Shell cleaning: shell cleaning machine, shell shaking time 1-2min; the shell shaking time ensures complete separation of the shell from the casting and prevents cracks on the surface of the casting.

[0122] After shell cleaning, the casting is subjected to water gate grinding to remove excess water gate and sprue.

[0123] Compared with Example 1, Example 2 reduces the number of inner gates and the number of shell layers, which is beneficial for heat dissipation and cooling of the mold, avoids accumulation of materials at the bottom of the shell, and shortens the production cycle of the product and saves costs.

[0124] Compared with Example 1, in the shell making process, the assembly scheme is changed to 2-face assembly of wax pieces, which avoids the problem of uneven shell thickness and accumulation of materials at the bottom due to excessive wax pieces during the slurry control process.

[0125] The mold of the embodiment 1 is modified according to the shrinkage of the castings in the previous test, the outer diameter size of the mold is modified to 44.9 (the required size of the castings is 44.5), the outer contour of the castings only needs to be manually shaped, and the size requirement can be met, without the need for three times of shaping using the mold, reducing the working load of the shaping process, and improving the production efficiency of the product.

[0126] In the description of the present application, each embodiment focuses on the difference from other embodiments, and the same and similar parts between various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the method part.

[0127] In the description of the present application, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or equipment. Without more limitation, the element limited by the sentence "including a…" does not exclude the existence of other same elements in the process, method, article or equipment including the element.

[0128] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature is "on", "above" and "on" the second feature, which can be directly above or obliquely above the first feature, or only indicates that the first feature is higher than the second feature in horizontal height. The first feature is "under", "below" and "below" the second feature, which can be directly below or obliquely below the first feature, or only indicates that the first feature is lower than the second feature in horizontal height.

[0129] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0130] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can modify, modify, replace and modify the above-described embodiments within the scope of the present application.

Claims

1. A method of investment casting a gyro case for an aircraft, characterized by, The method comprises: Step S1: injecting raw material wax into a mold to produce a wax mold; Step S2: soaking the wax mold in a surface layer slurry, the surface layer slurry being compounded and proportioned as follows: silica sol: lubricant: zirconium powder: defoaming agent = 0.9-1.1: 2.3-2.5: 3.5-3.7: 1.9-2.1, the viscosity of the surface layer slurry being controlled to be 41-47s, the wax mold being coated with 130-150 mesh zirconium sand, the wax mold after coating being dried, the drying time being controlled to be 6-8h, to obtain a first wax mold; Step S3: soaking the first wax mold in a first transition layer slurry, the first transition layer slurry being compounded as follows: silica sol: zirconium powder = 0.9-1.1: 2.3-2.5, the viscosity of the first transition layer slurry being controlled to be 10-12s, the first wax mold being coated with 25-50 mesh mullite sand, the first wax mold after coating being dried, the drying time being controlled to be 10-16h, to obtain a second wax mold; Step S4: soaking the second wax mold in a second transition layer slurry, the second transition layer slurry being compounded as follows: silica sol: mullite powder: zirconium powder = 0.9-1.1: 0.9-1.1: 1.7-1.9, the viscosity of the second transition layer slurry being controlled to be 11-17s, the second wax mold being coated with 25-50 mesh mullite sand, the second wax mold after coating being dried, the drying time being controlled to be 16-24h, to obtain a third wax mold; Step S5: soaking the third wax mold in a back layer slurry, the back layer slurry being compounded as follows: silica sol: mullite powder = 0.9-1.1: 1.4-16, the viscosity of the back layer slurry being controlled to be 11-17s, the third wax mold being coated with 16-30 mesh mullite sand, the third wax mold after coating being dried, the drying time being controlled to be 16-24h, to obtain a fourth wax mold; Step S6: soaking the fourth wax mold in a sealing slurry, the sealing slurry being compounded as follows: silica sol: mullite powder = 0.9-1.1: 0.9-1.1, the viscosity of the sealing slurry being controlled to be 8-12s, the fourth wax mold being dried, the drying time being controlled to be 16-24h, to obtain a fifth wax mold; Step S7: performing dewaxing treatment on the fifth wax mold to obtain a shell; Step S8: performing baking on the shell.

2. A method of investment casting a gyro case for an aircraft according to claim 1, wherein, The method further comprises: Step S9: pouring: pouring molten metal into the shell after baking, the time from the completion of baking to the start of pouring being controlled to be 10-20s, the pouring temperature being controlled to be 1650-1670℃, and the pouring time being controlled to be 8-12s.

3. A method of investment casting a gyro case for an aircraft according to claim 2, wherein, The method further comprises: Step S10: after the shell is poured with the molten metal, a heat preservative is sprinkled at the opening of the shell, and the shell is placed in a closed environment.

4. A method of investment casting a gyro case for an aircraft according to claim 3, wherein The method further comprises: Step S11: performing shock cleaning on the shell after pouring to obtain a casting.

5. A method of investment casting a gyro case for an aircraft as defined in claim 1, wherein, In the method, step S1 comprises: In the case of injecting the raw material wax into the mold, the wax injection temperature is controlled to be 54-58℃, the wax injection pressure is controlled to be 2-3MPa, the wax injection time is controlled to be 25-35s, and the wax mold is placed for more than or equal to 4h after the wax mold is completed.

6. A method of investment casting a gyro case for an aircraft as defined in claim 1, wherein, The step S1 in the method comprises: The wax mold is placed in a cleaning agent for cleaning, and the cleaning agent is neutral.

7. A method of investment casting a gyro case for an aircraft as defined in claim 1, wherein The step S1 in the method comprises: A plurality of the wax molds are cast, and the plurality of the wax molds are fixedly connected with the raw material wax as the shaft.

8. A method of investment casting a gyro case for an aircraft as defined in claim 1, wherein, The step S7 in the method comprises: The dewaxing temperature is controlled to be 175-185℃, the dewaxing pressure is controlled to be 0.75-1.0MPa, and the dewaxing time is controlled to be 15-20min.

9. A method of investment casting a gyro case for an aircraft as defined in claim 1, wherein, The step S8 in the method comprises: The baking temperature of the shell is controlled to be 1080-1120℃, the baking time is controlled to be 40-50min, then the heating is stopped, and the shell is completed baking when the temperature is reduced to 820-830℃.

10. The method according to claim 1, wherein the step S5 is repeated 1-3 times. ​

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