Casting method for improving looseness defect of large-size thin-wall thick support plate blade

Abstract

The invention provides a casting method for improving the looseness defect of a large-size thin-wall thick support plate blade, and relates to the technical field of blade casting, the casting method comprises the following steps: S1, preparing surface layer slurry; s2, preparing transition layer slurry; s3, preparing reinforcing layer slurry; s4, mixing to obtain a composite pasty slurry; s5, pasting the composite paste slurry; s6, roasting the mold shell; s7, filling refractory ceramic heat preservation cotton; according to the support plate blade casting produced by using the shell preparation process for improving the heat dissipation condition of the local position of the shell and the shell wrapping process capable of specifically adjusting the solidification sequence of the blade body, the internal loose defect proportion is reduced to 20% from 70%, and the casting percent of pass is greatly improved. In addition, due to the existence of the heat preservation cotton, the solidification speed of the molten metal within the 1 / 3 range of the blade body and the 1 / 3 range of the lower portion of the blade body is reduced, sequential solidification from the middle of the blade body to the upper portion and the lower portion of the blade body is formed, the feeding effect is enhanced, and the loose defect of the blade body is overcome.

Description

Technical Field

[0001] The invention relates to the technical field of blade casting, and in particular to a casting method for improving the looseness defect of large-sized thin-walled and thick-bracket blades. Background Art

[0002] In the structure of aircraft engines, support blades play a key role in turbine outlet straightening and engine support. The blade body wall thickness of a certain type of engine support blade casting is thin, with the thinnest part being only 1mm. The upper and lower mounting plates have a large span, with a length of 240mm in the leading and trailing edge directions. The wall thickness varies greatly, with the thinnest part of the mounting plate being only 2.5mm thick and the thickest part being 15mm thick. The overall structure of the support blade determines that the support blade body cannot be effectively compensated for shrinkage, and heat concentration is easily generated at the transition radius between the blade body and the edge plate during the solidification process, and loose defects are easily generated at the transition radius and on the blade body, resulting in a low casting qualification rate for the casting. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a casting method for improving the porosity defects of large-sized thin-walled thick support plate blades, thereby solving the problem of low casting qualification rate due to the easy occurrence of porosity defects in existing castings.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A casting method for improving the loose defects of large-sized thin-walled thick support plate blades comprises the following steps:

[0006] S1. Prepare surface layer slurry for supporting plate blade shell making, and make surface layer shell;

[0007] S2, preparing transition layer slurry for supporting plate blade shell making, the components of transition layer slurry include binder and refractory powder, and making transition layer shell;

[0008] S3, preparing reinforcement layer slurry for supporting plate blade shell making, the components of the reinforcement layer slurry include binder and refractory powder, and making the third to fourth reinforcement layer shell;

[0009] S4, mixing and stirring the fiber material, silica sol and bauxite powder to form a composite paste slurry consisting of a refractory material, a binder and a fiber material;

[0010] S5. When preparing the fifth layer of shell, the composite paste slurry is pasted at the transition position where loose defects are likely to occur, and the sixth to eighth layers of shell are continuously prepared after drying;

[0011] S6. After the shell is made, the shell is baked according to the general blade casting process. The fiber material burns during the shell baking process, and a cavity is generated at the transition radius. The shell thickness at the cavity is 1 to 2 mm thinner than other positions, and the heat dissipation speed is faster, which can accelerate the solidification speed of the metal liquid at the transition radius, thereby improving the loose defect at the transition radius.

[0012] S7. After the shell is baked, the shell is wrapped by the following process: refractory ceramic insulation cotton is inserted into the inner cavity 4 of the blade shell near the opening of the upper mounting plate 2 to the upper 1 / 3 of the blade body height; refractory ceramic insulation cotton is inserted into the inner cavity 4 of the blade shell near the outlet of the lower mounting plate 3 to the lower 1 / 3 of the blade body height. The insulation cotton is used to slow down the solidification rate of the molten metal within the 1 / 3 range of the blade body and the lower 1 / 3 range of the blade body, forming a sequential solidification from the middle of the blade body to the upper and lower parts of the blade body, thereby enhancing the shrinkage compensation effect and reducing the loose defects of the blade body.

[0013] Preferably, the components of the surface layer slurry in step 1 include a binder, refractory ceramic material powder, a grain refiner, a defoamer and a wetting agent, the powder-liquid ratio of the surface layer slurry ranges from 2.5:1 to 3.5:1, and the slurry viscosity ranges from 25s to 35s.

[0014] Preferably, the powder-liquid ratio of the transition layer slurry in step 2 is in the range of 1.5:1 to 2.5:1, and the slurry viscosity is in the range of 10 to 15s.

[0015] Preferably, the powder-liquid ratio of the reinforcement layer slurry in step 3 is in the range of 1:1 to 2:1, and the slurry viscosity is in the range of 8 to 12s.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The proportion of internal loose defects of the support blade castings produced by the shell preparation process for improving the heat dissipation conditions of the local position of the shell and the shell wrapping process for adjusting the solidification sequence of the blade and blade body according to the present invention has been reduced from 70% to 20%, greatly improving the qualified rate of castings. The delivery of the support blade castings of this type of engine is guaranteed.

[0018] (2) The present application slows down the solidification rate of the molten metal within the upper 1 / 3 of the blade body and the lower 1 / 3 of the blade body through the presence of the thermal insulation cotton, forming a sequential solidification from the middle of the blade body to the upper and lower parts of the blade body, thereby enhancing the shrinkage compensation effect and reducing the loose defects of the blade body. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the three-dimensional structure of the support plate blade from the first perspective;

[0020] Figure 2It is a schematic diagram of the three-dimensional structure of the support plate blade from a second perspective;

[0021] Figure 3 It is a schematic diagram of the three-dimensional structure of the support plate blade from the third perspective;

[0022] Figure 4 It is a schematic diagram of the side view structure of the support plate blade.

[0023] In the figure: 1. Blade body; 2. Upper mounting plate; 3. Lower mounting plate; 4. Inner cavity of blade shell; 5. Cotton placement; 6. Transition radius. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] like Figures 1 to 4 A casting method for improving the looseness defect of large-sized thin-walled thick support plate blades is shown, comprising the following steps:

[0026] S1. Prepare the surface layer slurry for the support plate blade shell, the binder used is silica sol with SiO2 content of 28% to 30%, the refractory powder used is zircon powder with a particle size of 320#, the defoamer used is silicone oil defoamer, the wetting agent used is JFC, the powder-liquid ratio of zircon powder to silica sol is 2.5:1 to 3.5:1, the slurry viscosity range is 25s to 35s, and the addition ratio of silicone oil defoamer and JFC wetting agent is 0.2% to 0.6%;

[0027] The assembled support plate blade wax mold is immersed in the surface layer slurry. After the wax mold is evenly covered with the slurry, the sanding operation is performed. After drying, the surface layer shell preparation is completed;

[0028] S2. Prepare transition layer slurry for supporting plate blade shell making, the binder used is silica sol with SiO2 content of 28% to 30%, the refractory powder used is corundum powder with particle size of 320#, the powder-liquid ratio of corundum powder to silica sol is 1.5:1 to 2.5:1, and the slurry viscosity ranges from 10 to 15s;

[0029] The rear support plate blade module that has completed the surface layer operation is immersed in the transition layer slurry. After the slurry is evenly adhered to the surface of the module, the sanding operation is performed. After drying, the transition layer shell preparation is completed;

[0030] S3. Prepare reinforcement layer slurry for supporting plate blade shell making, the binder used is silica sol with SiO2 content of 28% to 30%, the refractory powder used is 320# bauxite powder, the powder-liquid ratio of bauxite powder to silica sol is in the range of 1:1 to 2:1, and the slurry viscosity is in the range of 8 to 12s;

[0031] The rear support plate blade module that has completed the transition layer operation is immersed in the reinforcement layer slurry. After the slurry is evenly adhered to the surface of the module, the sand spraying operation is carried out. After drying, the third layer of shell preparation is completed. Repeat the above operation to complete the fourth layer of shell preparation.

[0032] S4, mixing and stirring the fiber material, silica sol and bauxite powder to form a composite paste slurry composed of a refractory material, a binder and a fiber material, wherein the fiber material used is a mixture of a non-woven fabric and paper scraps, firstly preparing a reinforcement layer slurry according to the reinforcement layer slurry preparation method described in step 3, and then adding the fiber material mixture thereto until the slurry is in a paste state, thereby completing the preparation of the composite paste slurry;

[0033] S5, when preparing the fifth layer of shell, paste the composite paste slurry at the transition R position where loose defects are likely to occur, and continue to prepare the sixth to eighth layers of shells in the manner described in step three after drying;

[0034] S6. After the shell is made, the support plate blade module is baked in a natural gas trolley furnace. The fiber material burns during the shell baking process, and a cavity is generated at the transition radius. The shell thickness at the cavity is 1 to 2 mm thinner than other positions, and the heat dissipation speed is faster, which can accelerate the solidification speed of the molten metal at the transition radius, thereby improving the loose defects at the transition radius.

[0035] S7. After the shell is fired, the shell is wrapped by the following process: refractory ceramic insulation cotton is inserted into the inner cavity of the blade shell near the opening of the upper mounting plate to the upper 1 / 3 of the height of the blade body 1, and refractory ceramic insulation cotton is inserted into the inner cavity of the blade shell near the outlet of the lower mounting plate to the lower 1 / 3 of the height of the blade body 1. The ceramic insulation cotton used is zirconium-containing insulation cotton, and its specification is 3mm to 20mm in thickness;

[0036] The presence of the insulation cotton slows down the solidification speed of the molten metal within the upper 1 / 3 range and the lower 1 / 3 range of the blade body 1, forming a sequential solidification from the middle of the blade body 1 to the upper and lower parts of the blade body 1, thereby enhancing the shrinkage compensation effect and reducing the loose defects of the blade body 1.

[0037] The proportion of internal loose defects of the support plate blade casting produced by the shell preparation process for improving the heat dissipation conditions of the local position of the shell and the shell wrapping process for adjusting the solidification sequence of the blade body 1 in a targeted manner according to the present invention is reduced from 70% to 20%, which greatly improves the qualified rate of the casting and ensures the delivery of the support plate blade casting of this type of engine.

[0038] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A casting method for improving the loose defects of large-sized thin-walled thick support plate blades, characterized in that: The steps include: S1. Prepare surface layer slurry for supporting plate blade shell making, and make surface layer shell; S2, preparing transition layer slurry for supporting plate blade shell making, the components of transition layer slurry include binder and refractory powder, and making transition layer shell; S3, preparing reinforcement layer slurry for supporting plate blade shell making, the components of the reinforcement layer slurry include binder and refractory powder, and making the third to fourth reinforcement layer shell; S4, mixing and stirring the fiber material, silica sol and bauxite powder to form a composite paste slurry consisting of a refractory material, a binder and a fiber material; S5, when preparing the fifth layer of shell, the composite paste slurry is pasted at the transition position where loose defects are likely to occur, and the sixth to eighth layers of shell are continuously prepared after drying; S6. After the shell is made, the shell is baked according to the general blade casting process. The fiber material burns during the shell baking process, and a cavity is generated at the transition radius. The shell thickness at the cavity is 1 to 2 mm thinner than other positions, and the heat dissipation speed is faster, which can accelerate the solidification speed of the metal liquid at the transition radius, thereby improving the loose defect at the transition radius. S7. After the shell is fired, the shell is wrapped by the following process: refractory ceramic insulation cotton is inserted into the cotton position (5) from the opening of the upper mounting plate (2) to the upper 1 / 3 of the height of the blade body (1) in the inner cavity (4) of the blade shell, and refractory ceramic insulation cotton is inserted into the cotton position (5) from the outlet of the lower mounting plate (3) to the lower 1 / 3 of the height of the blade body (1) in the inner cavity (4) of the blade shell. The insulation cotton is used to slow down the solidification rate of the molten metal within the upper 1 / 3 range and the lower 1 / 3 range of the blade body (1), thereby forming a sequential solidification from the middle of the blade body (1) to the upper and lower parts of the blade body (1), thereby enhancing the shrinkage compensation effect and reducing the loose defects of the blade body (1).

2. A casting method for improving the looseness defect of large-sized thin-walled thick support plate blades according to claim 1, characterized in that: The components of the surface layer slurry in step 1 include a binder, refractory ceramic material powder, a grain refiner, a defoamer and a wetting agent. The powder-liquid ratio of the surface layer slurry is in the range of 2.5:1 to 3.5:1, and the slurry viscosity is in the range of 25s to 35s.

3. A casting method for improving the looseness defect of large-sized thin-walled thick support plate blades according to claim 1, characterized in that: The powder-to-liquid ratio of the transition layer slurry in step 2 is in the range of 1.5:1 to 2.5:1, and the slurry viscosity is in the range of 10 to 15s.

4. A casting method for improving the looseness defect of large-sized thin-walled thick support plate blades according to claim 1, characterized in that: The powder-to-liquid ratio of the reinforcement layer slurry in step 3 is in the range of 1:1 to 2:1, and the slurry viscosity is in the range of 8 to 12s.

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