Investment casting method for gyroscope chamber for aviation

Abstract

The invention relates to an investment casting method for an aviation gyro chamber. The investment casting method comprises the following steps: injecting raw material wax into a mold to prepare a wax mold; a wax mold is immersed in the surface layer slurry to be soaked, and a first wax mold is obtained; the first wax mold is immersed in the first transition layer slurry to be soaked, and a second wax mold is obtained; a second wax mold is soaked in second transition layer slurry, sand hanging is conducted on the second wax mold through mullite sand, the second wax mold subjected to sand hanging is dried, and a third wax mold is obtained; the third wax mold is immersed in the back layer slurry to be soaked, coated with sand and dried, and a fourth wax mold is obtained; the fourth wax mold is immersed in the sealing slurry to be soaked and dried, and a fifth wax mold is obtained; and dewaxing treatment is conducted on the fifth wax mold, and a mold shell is obtained and roasted. According to the smelting and casting method, the product quality is improved, the production process is shortened, and the production cost is reduced by improving the components of a wax mold and slurry, improving the mold design and the assembling mode of a wax piece and adopting a corresponding shell manufacturing process of the wax piece.

Description

Technical Field

[0001] The invention relates to the technical field of aviation engines, and in particular to an investment casting method for an aviation gyroscope house. Background Art

[0002] The aviation gyro room is an important device in the aviation field. It provides a stable installation environment for the gyro and protects the gyro from external environmental influences such as vibration, shock, temperature changes, etc. Aviation gyro rooms usually need to meet high precision requirements to ensure that the gyro can accurately measure the attitude and heading of the aircraft. In addition, since the gyro plays a vital role in flight safety, aviation gyro rooms need to have high reliability.

[0003] Therefore, the surface and internal quality requirements of aviation gyroscope housing products are relatively high. During the casting process, affected by the shrinkage rate of the molten metal, the shrinkage at different wall thickness positions is different and difficult to control, resulting in increased product size deviation. In order to ensure the size and shape requirements of the product, three shaping operations are required. The strength of this material product is relatively high, and the shaping pressure cannot be controlled. Cracks appear in local parts of the product, which require subsequent welding repairs. The production process is cumbersome, which increases production costs and prolongs the production cycle. In addition, due to the uneven wall thickness of the casting, shrinkage cavities and shrinkage defects are very likely to occur in areas with larger wall thickness during the casting process, which reduces the product yield. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method for investment casting of a gyroscope house for aviation, which solves the technical problems in the prior art that the production of gyroscope houses may cause cracks in local parts of the product, require subsequent welding repairs, and have complicated production processes.

[0006] (II) Technical solution

[0007] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0008] An embodiment of the present invention provides an investment casting method for a gyroscope room for aviation, the method comprising:

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

[0010] Step S2: immersing the wax model in the surface slurry, the ingredients and proportions of the surface slurry are: silica sol: lubricant: zircon powder: defoamer = 0.9-1.1: 2.3-2.5: 3.5-3.7: 1.9-2.1, the viscosity of the surface slurry is controlled to be 41s-47s, 130-150 mesh zircon sand is used to sand the wax model, and the sanded wax model is dried, and the drying time is controlled to be 6h-8h to obtain the first wax model;

[0011] Step S3: immersing the first wax mold in the first transition layer slurry, the first transition layer slurry ingredients are: silica sol: zircon powder = 0.9-1.1: 2.3-2.5, the first transition layer slurry viscosity is controlled to be 10s-12s, 25-50 mesh mullite sand is used to sand the first wax mold, and the first wax mold after sanding is dried, and the drying time is controlled to be 10h-16h to obtain the second wax mold;

[0012] Step S4: immersing the second wax mold in the second transition layer slurry, the second transition layer slurry ingredients are: silica sol: mullite powder: zircon 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, 25-50 mesh mullite sand is used to sand the second wax mold, and the sanded second wax mold is dried, and the drying time is controlled to be 16h-24h to obtain the third wax mold;

[0013] Step S5: immersing the third wax mold in the backing layer slurry, the backing layer slurry ingredients are: silica sol: mullite = 0.9-1.1: 1.4-16, the viscosity of the backing layer slurry is controlled to be 11s-17s, and the third wax mold is sanded with 16-30 mesh mullite sand, and the sanded third wax mold is dried, and the drying time is controlled to be 16h-24h to obtain a fourth wax mold;

[0014] Step S6: immersing the fourth wax model in a sealing slurry, wherein the sealing slurry is prepared as follows: silica sol: mullite powder = 0.9-1.1: 0.9-1.1, and the viscosity of the sealing slurry is controlled to be 8s-12s, and the fourth wax model is dried, and the drying time is controlled to be 16h-24h, to obtain a fifth wax model;

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

[0016] Step S8: calcining the shell.

[0017] Preferably, the method further comprises:

[0018] Step S9: Casting: Casting the molten metal into the calcined shell, the time from the shell being taken out of the furnace after calcination to the start of casting is controlled within 10s to 20s, the casting temperature is controlled at 1650°C to 1670°C, and the casting time is controlled at 8s to 12s.

[0019] Preferably, the method further comprises:

[0020] Step S10: After pouring the molten metal into the mold shell, a heat-insulating agent is sprinkled on the opening of the mold shell, and the mold shell is placed in a closed environment.

[0021] Preferably, the method further comprises:

[0022] Step S11: the mold shell after casting is vibrated and cleaned, and the vibrating and cleaning time is controlled to be 1 to 2 minutes to obtain a casting.

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

[0024] When the raw wax is injected into the mold, the wax injection temperature is controlled to be 54°C ~ 58°C, the wax injection pressure is controlled to be 2MPa ~ 3MPa, the wax injection time is controlled to be 25s ~ 35s, and the placement time after the wax mold is completed is greater than or equal to 4h.

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

[0026] Place the wax model in a neutral cleaning agent for cleaning.

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

[0028] Cast multiple wax models, and fix the multiple wax models together using the raw wax as an axis.

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

[0030] The dewaxing temperature is controlled at 175-185°C, the dewaxing pressure is controlled at 0.75-1.0MPa, and the dewaxing time is controlled at 15-20min.

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

[0032] The baking temperature of the shell is controlled to be 1080°C to 1120°C, and the baking time is controlled to be 40min to 50min. Then the heating is stopped. When the temperature drops to 820°C to 830°C, the shell is baked.

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

[0034] (III) Beneficial effects

[0035] The beneficial effects of the present invention are as follows: the present application mentions a method for investment casting of a gyroscope room for aviation, the method comprising: injecting raw wax into a mold to make a wax mold; immersing the wax mold in a surface layer slurry to obtain a first wax mold; immersing the first wax mold in a first transition layer slurry to obtain a second wax mold; immersing the second wax mold in a second transition layer slurry and using mullite sand to sand the second wax mold, drying the sanded second wax mold to obtain a third wax mold; immersing the third wax mold in a back layer slurry to sand and dry to obtain a fourth wax mold; immersing the fourth wax mold in a sealing slurry to obtain a fifth wax mold; dewaxing the fifth wax mold to obtain a shell and bake it. The present application mentions a method for investment casting of a gyroscope house for aviation. The melting and casting method improves product quality, shortens the production process and reduces production costs 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, as well as the mold design and the assembly method of the wax parts, and the corresponding shell making process of the wax parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic flow chart of an investment casting method for a gyroscope room for aviation of the present invention;

[0037] Figure 2 It is a schematic diagram of the nozzle design in Example 1 of the investment casting method for a gyroscope room for aviation of the present invention;

[0038] Figure 3 It is a schematic diagram of the wax parts assembly method in Example 1 of the investment casting method of an aviation gyroscope room of the present invention;

[0039] Figure 4 It is a schematic diagram of the nozzle design in Example 2 of the investment casting method for a gyroscope room for aviation of the present invention;

[0040] Figure 5 This is a schematic diagram of the wax parts assembly method in Example 2 of the investment casting method for an aviation gyroscope room of the present invention. DETAILED DESCRIPTION

[0041] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0042] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0043] In these embodiments, unless otherwise specified, the parts and percentages are all measured by mass. "Parts by mass" refers to the basic unit of measurement representing the mass ratio relationship of multiple components. 1 part can represent any unit mass, such as 1g, 3.527g, etc. If we say that the mass parts of component A are a parts and the mass parts of component B are b parts, it means 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 the mass parts, the sum of the mass parts of all components is not limited to 100 parts. "And / or" is used to indicate that one or both of the situations described may occur, for example, A and / or B include (A and B) and (A or B).

[0044] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention 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 and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0045] refer to Figure 1 In this technical solution, the above method includes the following steps:

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

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

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

[0049] Step S2: immersing the wax model into the surface slurry for hanging, the ingredients and proportions of the surface slurry are: silica sol: lubricant: 350 mesh zircon powder: defoamer = 0.9-1.1: 2.3-2.5: 3.5-3.7: 1.9-2.1, the viscosity of the surface slurry is controlled to be 41s-47s, 130-150 mesh zircon sand is used to hang sand on the wax model, and the wax model after hanging sand is dried, and the drying time is controlled to be 6h-8h to obtain the first wax model;

[0050] It should be noted that the above-mentioned wax model is immersed in the surface layer slurry made according to the above-mentioned ingredients and proportions. Before applying the surface layer slurry, the surface layer slurry should be stirred evenly to reduce the precipitation of materials in the surface layer slurry as much as possible so that the surface layer slurry can fill and wet the molten mold well.

[0051] For example, when the surface slurry is applied, the wax model can be immersed in the surface slurry and shaken left and right and up and down so that the surface slurry can wet the wax model well and evenly cover the surface of the wax model. After the coating is applied, sanding can be performed, and the wax model can be sanded with 130-150 mesh zirconium sand, and the wax model after sanding is dried, and the drying time is controlled to be 6h-8h to obtain the first wax model.

[0052] It should be noted that the mullite sand is a refractory sand material, and a dense refractory coating can be formed on the surface of the wax mold by controlling the first wax mold to dry and harden under a specific temperature and humidity.

[0053] Step S3: immersing the first wax mold in a first transition layer slurry, wherein the first transition layer slurry is formulated as follows: silica sol: 325 mesh zircon powder = 0.9-1.1: 2.3-2.5, and the viscosity of the first transition layer slurry is controlled to be 10s-12s. The first wax mold is sanded with 25-50 mesh mullite sand, and the sanded first wax mold is dried, and the drying time is controlled to be 10h-16h to obtain a second wax mold.

[0054] It should be noted that the first wax model is immersed in the first transition layer slurry made according to the above ingredients and proportions. Before applying the first transition layer slurry, the first transition layer slurry should be stirred evenly to reduce the precipitation of the material in the first transition layer slurry as much as possible so that the first transition layer slurry can fill and wet the molten mold well.

[0055] For example, when the first transition layer slurry is applied, the first wax model can be immersed in the first transition layer slurry and shaken left and right and up and down so that the first transition layer slurry can wet the wax model well and evenly cover the surface of the first wax model. After the coating is applied, sanding can be performed, and 25-50 mesh mullite sand can be used to sand the first wax model, and the first wax model after sanding is dried, and the drying time is controlled to be 10h to 16h to obtain the second wax model.

[0056] Step S4: immersing the second wax mold in a second transition layer slurry, wherein the second transition layer slurry is formulated as follows: silica sol: mullite powder: 325 mesh zircon powder = 0.9-1.1: 0.9-1.1: 1.7-1.9, and the viscosity of the second transition layer slurry is controlled to be 11s-17s, and 25-50 mesh mullite sand is used to sand the second wax mold, and the sanded second wax mold is dried, and the drying time is controlled to be 16h-24h to obtain a third wax mold;

[0057] Step S5: immersing the third wax mold in a backing layer slurry, wherein the backing layer slurry is prepared as follows: silica sol: 200 mesh mullite powder = 0.9-1.1: 1.4-16, and the viscosity of the backing layer slurry is controlled to be 11s-17s, and the third wax mold is sanded with 16-30 mesh mullite sand, and the sanded third wax mold is dried, and the drying time is controlled to be 16h-24h, to obtain a fourth wax mold;

[0058] Step S6: immersing the fourth wax model in a sealing slurry, wherein the sealing slurry is prepared as follows: silica sol: 200 mesh mullite powder = 0.9-1.1: 0.9-1.1, and the viscosity of the sealing slurry is controlled to be 8s-12s, and the fourth wax model is dried, and the drying time is controlled to be 16h-24h, to obtain a fifth wax model;

[0059] Step S7: dewaxing the fifth wax pattern to obtain a shell;

[0060] It should be noted that the dewaxing treatment is performed on the fifth wax mold. For example, the fifth wax mold can be heated to melt the raw wax in the fifth wax mold, and then the wax liquid of the raw wax can be poured out.

[0061] Step S8: calcining the shell.

[0062] For example, reference Figure 3 or Figure 5 A pouring port is left, and after the mold shell is roasted at high temperature, casting can be carried out to produce castings.

[0063] In this technical solution, the above method also includes:

[0064] Step S9: Casting: Casting liquid metal on the above-mentioned shell after roasting, the time from the shell being taken out of the furnace after roasting to the start of casting is controlled to be 10s to 20s, the casting temperature is controlled to be 1650℃ to 1670℃, and the casting time is controlled to be 8s to 12s.

[0065] It should be noted that in the prior art, in the production Figure 2 or Figure 3When casting the gyroscope house shown in the figure, due to the uneven wall thickness of the casting, shrinkage cavities and shrinkage defects are easily generated at the thicker wall during the casting process, which reduces the yield of the product. By setting the above-mentioned casting time, operation time and temperature range, the shrinkage cavities and shrinkage defects of the wall thickness can be reduced, thereby improving the quality and yield of the casting.

[0066] In this technical solution, the above method also includes:

[0067] Step S10: After the above-mentioned molten metal is cast into the above-mentioned mold shell, a heat-insulating agent is sprinkled on the opening of the above-mentioned mold shell, and the above-mentioned mold shell is placed in a closed environment.

[0068] It should be noted that the opening of the above-mentioned shell is the pouring gate for pouring molten metal.

[0069] For example, after the shell is filled with liquid metal, a heat-insulating agent may be sprinkled at the pouring gate to prevent a sudden drop in temperature at the pouring gate after the casting is completed, thereby reducing the fluidity of the liquid in the shell.

[0070] For example, bricks are placed underneath the mold shell after casting, and the entire mold shell can be placed in a barrel for 8 to 24 hours to prevent air leakage.

[0071] In this technical solution, the above method also includes:

[0072] Step S11: the mold shell after casting is vibrated and cleaned, and the vibrating and cleaning time is controlled to be 1 to 2 minutes to obtain a casting.

[0073] Illustratively, the shell mold after casting is vibrated to obtain a casting. A shell vibrator can be used to vibrate the shell, and the shell vibration time is controlled to be 1 to 2 minutes. The shell vibration time can ensure that the shell mold is completely detached from the casting and that the surface of the casting will not be cracked or damaged.

[0074] In the technical solution, step S1 in the above method includes:

[0075] When the raw wax is injected into the mold, the wax injection temperature is controlled to be 54°C ~ 58°C, the wax injection pressure is controlled to be 2MPa ~ 3MPa, the wax injection time is controlled to be 25s ~ 35s, and the placement time after the above wax mold is completed is greater than or equal to 4h.

[0076] It should be noted that when using a mold to prepare a wax model, you can check whether the wax injection port of the mold is aligned with the wax injection nozzle of the machine, and at the same time check whether the opening and closing of the mold is smooth.

[0077] In the technical solution, step S1 in the above method includes:

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

[0079] It should be noted that the wax film cleaning agent can act on the surface of the wax mold to dissolve and remove the oil film layer such as the release agent adsorbed on the surface of the wax mold and affecting the slurry hanging.

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

[0081] Cast a plurality of the wax molds, and fix the plurality of wax molds together using the raw wax as an axis.

[0082] For example, reference Figures 2 to 5 , multiple wax models can be cast, and according to Figure 2 or Figure 4 The wax model is assembled in a tree manner, and a plurality of the above wax models are fixedly connected with the above raw wax as the axis, and Figure 3 or Figure 5 The shape shown provides for a tree configuration with at least one opening for pouring and / or discharge.

[0083] Exemplarily, the size of the wax rod with the raw wax as the axis can be 40mm*60mm*150mm.

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

[0085] The dewaxing temperature is controlled at 175-185°C, the pressure is controlled at 0.75-1.0MPa, and the dewaxing time is controlled at 15-20min.

[0086] It should be noted that controlling the temperature and pressure within the above range during the dewaxing process can allow the wax liquid to flow out smoothly and uninterruptedly, and less investment mold remains in the shell after dewaxing is completed.

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

[0088] The baking temperature of the shell is controlled to be 1080° C. to 1120° C., and the baking time is controlled to be 40 min to 50 min. Then the heating is stopped. When the temperature drops to 820° C. to 830° C., the shell is baked.

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

[0090] Embodiment 1:

[0091] First, make a wax model. Inject the raw wax into the mold, control the wax injection temperature to 56±2℃, control the wax injection pressure to 2.5±0.5MPa, and control the wax injection time to 30±5s. After the wax model is injected, take it out of the mold and cool it. After the wax model is made, it should be placed for more than 4 hours.

[0092] In Example 1, a plurality of the above wax models are cast and Figure 2 The wax model is assembled in a tree-like manner, and multiple wax models are fixedly connected with the raw wax as the axis. The size of the wax rod with the raw wax as the axis can be 40mm*60mm*150mm, and the wax parts are assembled in a 4-sided manner. Figure 3 Design the water injection port of the wax model, such as Figure 3 As shown, there are two water inlets in the design.

[0093] Place the assembled wax model in a neutral cleaning agent for cleaning.

[0094] The shell has 6.5 layers.

[0095] Surface layer: The slurry ingredients are silica sol: lubricant: 350 mesh zircon powder: defoaming agent = 1:2.4:3.6:2, and the viscosity is 44±3s; sand hanging: 130 mesh zircon sand; drying time: 6-8h.

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

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

[0098] Back layer (4th to 6th layers): each layer of slurry ingredients silica sol: 200 mesh mullite = 1:1.5, viscosity 14±3s; each layer of sand treatment: 16-30 mesh mullite sand; each layer is dried for 16-24 hours after sand treatment.

[0099] Sealing slurry: slurry ingredients: silica sol: 200 mesh mullite = 1:1, slurry viscosity is 10±2s, and the shell is dried for 16-24 hours after the slurry is applied.

[0100] Dewaxing: After the shell is made, dewaxing treatment is carried out, the dewaxing temperature is 175-185°C, the dewaxing pressure is 0.75-1.0MPa, and the dewaxing time is 15-20min.

[0101] casting

[0102] The shell is baked at 1100±20℃ for 45±5min. The shell must be baked thoroughly. Then stop the heat preservation and heating. When the temperature drops to 820-830℃, the shell is taken out of the furnace. Casting is carried out immediately after the shell is taken out of the furnace. The time from the shell being taken out of the furnace to the start of casting is controlled within 10-20s to reduce the temperature loss of the shell. The casting temperature is 1660℃±10℃, and the casting time is guaranteed to be within 10±2s. After the shell is filled with liquid metal, the gate should be sprinkled with heat preservation agent to prevent the temperature at the gate from dropping suddenly and reduce the fluidity of the liquid in the shell. The bottom of the cast shell should be padded and the entire shell should be buckled for 8-24h, and the buckle should be tightly buckled to prevent air leakage.

[0103] Shell cleaning: Shell vibrating machine, shell vibrating time is 1 to 2 minutes; this shell vibrating time can not only ensure that the shell is completely detached from the casting, but also ensure that there will be no cracks or damage on the surface of the casting.

[0104] After the shell is cleaned, the casting is ground to remove the excess sprue and runner.

[0105] Example 2

[0106] The wax mold nozzle design in this scheme is shown in Figure 4 This scheme designs 1 sprue, and the wax parts assembly method of this scheme adopts 2-side assembly.

[0107] Wax model making

[0108] The raw material for wax model making is medium-temperature wax, the wax injection temperature is 56±2℃, the wax injection pressure is 2.5±0.5MPa, and the wax injection time is 30±5s. After the wax parts are completed, they must be placed for more than 4 hours.

[0109] according to Figure 5 The wax parts are assembled in this way, and the wax rod size is 40mm*60mm*150mm.

[0110] Place the assembled wax model in a neutral cleaning agent for cleaning.

[0111] Shell Making

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

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

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

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

[0116] Back layer (4th to 5th layers): each layer of slurry ingredients silica sol: 200 mesh mullite = 1:1.5, viscosity 14±3s; each layer of sand treatment: 16-30 mesh mullite sand; each layer is dried for 16-24 hours after sand treatment.

[0117] Sealing slurry: slurry ingredients: silica sol: 200 mesh mullite = 1:1, slurry viscosity is 10±2s, and the shell is dried for 16-24 hours after the slurry is applied.

[0118] Dewaxing: After the shell is made, dewaxing treatment is carried out, the dewaxing temperature is 175-185°C, the dewaxing pressure is 0.75-1.0MPa, and the dewaxing time is 15-20min.

[0119] casting

[0120] The shell is baked at 1100±20℃ for 45±5min. The shell must be baked thoroughly. Then stop the heat preservation and heating. When the temperature drops to 820-830℃, the shell is taken out of the furnace. Casting is carried out immediately after the shell is taken out of the furnace. The time from the shell being taken out of the furnace to the start of casting is controlled within 10-20s to reduce the temperature loss of the shell. The casting temperature is 1660℃±10℃, and the casting time is guaranteed to be within 10±2s. After the shell is filled with liquid metal, the gate should be sprinkled with heat preservation agent to prevent the temperature at the gate from dropping suddenly and reduce the fluidity of the liquid in the shell. The bottom of the cast shell should be padded with bricks, and the entire shell should be buckled for 8-24h, and the buckling should be tight to prevent leakage and oxidation.

[0121] Shell cleaning: Shell vibrating machine, shell vibrating time is 1 to 2 minutes; this shell vibrating time can not only ensure that the shell is completely detached from the casting, but also ensure that there will be no cracks or damage on the surface of the casting.

[0122] After the shell is cleaned, the casting is ground to remove the excess sprue and runner.

[0123] Compared with Example 1, Example 2 reduces the number of inner gates and the number of shell layers, which is beneficial to the heat dissipation cooling of the mold and avoids material accumulation at the bottom of the shell that is not conducive to heat dissipation; on the other hand, it shortens the production cycle of the product and saves costs.

[0124] Compared with Example 1, in the shell making process, since the assembly scheme is changed to assembling wax parts on two sides, it is avoided that too many wax parts are bonded together, which is not conducive to the retention of slurry in the slurry control process, and uneven wall thickness of the shell and material accumulation at the bottom are avoided.

[0125] In Example 1, the mold is modified according to the shrinkage rate of the casting in the previous test. The outer circle size of the mold is modified to φ44.9 (the required size of the casting is φ44.5). The outer contour of the casting only needs to be manually shaped to meet the size requirements. There is no need to use the mold for shaping three times, which reduces the workload of the shaping process and improves the production efficiency of the product.

[0126] In the description of the present invention, each embodiment focuses on the differences from other embodiments, and the same or similar parts between the 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 parts can be referred to the method part description.

[0127] In the description of the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically limited. Moreover, the term "includes", "comprising" or any other variant thereof is 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 clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the sentence "comprising one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements.

[0128] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0129] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0130] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for investment casting of a gyroscope room for aviation, characterized in that: The method comprises: Step S1: injecting raw wax into a mold to make a wax mold; Step S2: immersing the wax model in a surface slurry, wherein the ingredients and proportions of the surface slurry are as follows: silica sol: lubricant: zircon powder: defoaming agent = 0.9-1.1: 2.3-2.5: 3.5-3.7: 1.9-2.1, the viscosity of the surface slurry is controlled to be 41s-47s, 130-150 mesh zircon sand is used to sand the wax model, and the sanded wax model is dried, and the drying time is controlled to be 6h-8h to obtain a first wax model; Step S3: immersing the first wax mold in a first transition layer slurry, wherein the first transition layer slurry is formulated as follows: silica sol: zircon powder = 0.9-1.1: 2.3-2.5, the viscosity of the first transition layer slurry is controlled to be 10s-12s, 25-50 mesh mullite sand is used to sand the first wax mold, and the first wax mold after sanding is dried, and the drying time is controlled to be 10h-16h to obtain a second wax mold; Step S4: immersing the second wax mold in a second transition layer slurry, wherein the second transition layer slurry is formulated as follows: silica sol: mullite powder: zircon powder = 0.9-1.1: 0.9-1.1: 1.7-1.9, and the viscosity of the second transition layer slurry is controlled to be 11s-17s. The second wax mold is sanded with 25-50 mesh mullite sand, and the sanded second wax mold is dried, and the drying time is controlled to be 16h-24h to obtain a third wax mold; Step S5: immersing the third wax model in a backing layer slurry, wherein the backing layer slurry is prepared as follows: silica sol: mullite powder = 0.9-1.1: 1.4-16, and the viscosity of the backing layer slurry is controlled to be 11s-17s, and the third wax model is sanded with 16-30 mesh mullite sand, and the sanded third wax model is dried, and the drying time is controlled to be 16h-24h, to obtain a fourth wax model; Step S6: immersing the fourth wax model in a sealing slurry, wherein the sealing slurry is prepared as follows: silica sol: mullite powder = 0.9-1.1: 0.9-1.1, and the viscosity of the sealing slurry is controlled to be 8s-12s, and the fourth wax model is dried, and the drying time is controlled to be 16h-24h, to obtain a fifth wax model; Step S7: dewaxing the fifth wax pattern to obtain a shell; Step S8: calcining the shell.

2. The method for investment casting of a gyroscope room for aviation according to claim 1, characterized in that: The method further comprises: Step S9: Casting: Casting liquid metal on the shell after roasting, the time from the shell being taken out of the furnace after roasting to the start of casting is controlled to be 10s to 20s, the casting temperature is controlled to be 1650°C to 1670°C, and the casting time is controlled to be 8s to 12s.

3. The method for investment casting of a gyroscope room for aviation according to claim 2, characterized in that: The method further comprises: Step S10: After the metal liquid is cast in the mold shell, a heat-insulating agent is sprinkled at the opening of the mold shell, and the mold shell is placed in a closed environment.

4. The method for investment casting of a gyroscope room for aviation according to claim 3, characterized in that: The method further comprises: Step S11: the mold shell after casting is vibrated and cleaned, and the vibrating and cleaning time is controlled to be 1 to 2 minutes to obtain a casting.

5. The method for investment casting of a gyroscope room for aviation according to claim 1, characterized in that: Step S1 in the method comprises: When the raw wax is injected into the mold, the wax injection temperature is controlled to be 54°C to 58°C, the wax injection pressure is controlled to be 2MPa to 3MPa, the wax injection time is controlled to be 25s to 35s, and the placement time after the wax mold is completed is greater than or equal to 4h.

6. The method for investment casting of a gyroscope room for aviation according to claim 1, characterized in that: Step S1 in the method comprises: The wax model is placed in a cleaning agent for cleaning, and the cleaning agent is neutral.

7. The method for investment casting of a gyroscope room for aviation according to claim 1, characterized in that: Step S1 in the method comprises: Cast a plurality of the wax molds, and fix the plurality of wax molds together using the raw wax as an axis.

8. The method for investment casting of a gyroscope room for aviation according to claim 1, characterized in that: Step S7 in the method comprises: The dewaxing temperature is controlled at 175-185°C, the dewaxing pressure is controlled at 0.75-1.0MPa, and the dewaxing time is controlled at 15-20min.

9. The method for investment casting of a gyroscope room for aviation according to claim 1, characterized in that: Step S8 in the method comprises: The baking temperature of the shell is controlled to be 1080° C. to 1120° C., and the baking time is controlled to be 40 min to 50 min. Then the heating is stopped. When the temperature drops to 820° C. to 830° C., the shell is baked.

10. The method for investment casting of a gyroscope room for aviation according to claim 1, characterized in that: The step S5 is repeated 1 to 3 times.

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