A method for avoiding equiaxed crystal blade transition R porosity

Abstract

The present invention provides a method for avoiding shrinkage porosity at the fillet R of equiaxed crystal blades, belonging to the technical field of casting preparation. When performing the first back layer sanding and the second back layer sanding in the present invention, the sand material at the fillet R is 20-80 mesh chilled iron sand, and the sand material at the remaining parts is 20-80 mesh white fused alumina sand; when performing the third back layer sanding, the fourth back layer sanding, and the fifth back layer sanding, the sand material at the fillet R is 20 mesh chilled iron sand, and the sand material at the remaining parts is 20 mesh white fused alumina sand. By changing the material of the mold shell, the present invention replaces white fused alumina sand with chilled iron sand at the fillet R, accelerates the heat dissipation of the fillet R, changes the local heat dissipation condition at the fillet R, enables it to solidify prior to the flange, avoids the shrinkage porosity defect at the fillet R, and thereby improves the qualified rate of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of casting preparation, and particularly relates to a method for avoiding shrinkage porosity at the fillet R of equiaxed crystal blades. Background Art

[0002] The power turbine part of a gas turbine engine blade consists of working blades (rotor blades) and guide vanes (stator blades). The guide vane is composed of an outer edge plate, a blade body, and an inner edge plate. As a typical casting in the hot end part, it generally adopts a complex thin-walled multi-blade joint structure and is manufactured by the equiaxed crystal process. However, due to the structural design of the guide vane itself, the thickness and heat dissipation of the mold shell are uneven, and shrinkage porosity defects are likely to occur in the casting. In particular, the fillet R position at the connection between the blade body and the edge plate is the last part of the casting to solidify. When solidifying, the molten metal at this place cannot be replenished from other places, resulting in shrinkage porosity defects at the fillet R.

[0003] Generally, a chill is often placed at the fillet R to accelerate the heat dissipation of the fillet R, so that the solidification speed of the molten metal at the fillet R is accelerated, achieving the effect of solidifying simultaneously with other parts. However, shrinkage porosity defects still exist at the fillet R. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for avoiding shrinkage porosity at the fillet R of equiaxed crystal blades. The method of the present invention can avoid shrinkage porosity defects at the fillet R of equiaxed crystal blades.

[0005] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a method for avoiding shrinkage porosity at the fillet R of equiaxed crystal blades, including the following steps:

[0007] Perform pretreatment on the wax pattern to obtain a pretreated wax pattern;

[0008] Apply the first surface layer slurry, sprinkle sand on the first surface layer, harden, apply the second surface layer slurry, and sprinkle sand on the second surface layer to the pretreated wax pattern in sequence to obtain a mold shell with a surface layer formed. The first surface layer slurry and the second surface layer slurry independently include the following components in parts by mass: 1 part of silica sol, 2 - 4 parts of mullite powder;

[0009] The shell for forming the facing layer is successively coated with the first back layer slurry, the first back layer sanding, hardened, coated with the second back layer slurry, the second back layer sanding, hardened, the third back layer slurry, the third back layer sanding, hardened, coated with the fourth back layer slurry, the fourth back layer sanding, hardened, the fifth back layer slurry, the fifth back layer sanding and hardened to obtain a shell for forming the back layer; the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry independently include the following components in parts by mass: 1 part of silica sol and 2 - 3.5 parts of white fused alumina powder; when performing the first back layer sanding and the second back layer sanding, the sand material at the transition R is 20 - 80 mesh chilled iron sand, and the sand material at the remaining parts is 20 - 80 mesh white fused alumina sand; when performing the third back layer sanding, the fourth back layer sanding and the fifth back layer sanding, the sand material at the transition R is 20 mesh chilled iron sand, and the sand material at the remaining parts is 20 mesh white fused alumina sand;

[0010] The shell for forming the back layer is sealed with slurry and then hardened.

[0011] Preferably, the particle sizes of the mullite powder and the white fused alumina powder are both 320 mesh.

[0012] Preferably, the first facing layer slurry and the second facing layer slurry independently further include a penetrant and / or an antifoaming agent.

[0013] Preferably, the viscosity is measured with a No. 4 coating cup, and the viscosities of the first facing layer slurry and the second facing layer slurry are independently 70 - 100 s.

[0014] Preferably, the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry independently further include a penetrant and / or an antifoaming agent.

[0015] Preferably, the viscosity is measured with a No. 4 coating cup, and the viscosities of the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry are independently 30 - 50 s.

[0016] Preferably, the 20 - 80 mesh chilled iron sand and the 20 mesh chilled iron sand are independently made of a metallic material or a non-metallic material. The metallic materials include cast iron and / or stainless steel, and the non-metallic materials include one or more of iron trioxide, silica sand and chromite sand.

[0017] Preferably, the sand materials for the first facing layer sanding and the second facing layer sanding are both 80 mesh white fused alumina sand.

[0018] Preferably, the slurry for sealing includes the following components in parts by mass: 1 part of silica sol and 2 - 3.5 parts of white fused alumina powder.

[0019] The present invention provides a method for avoiding shrinkage porosity at the transition R of equiaxed crystal blades, comprising the following steps: pretreating a wax film to obtain a pretreated wax film; successively applying a first surface layer slurry, sanding the first surface layer, hardening, applying a second surface layer slurry, and sanding the second surface layer to obtain a shell with a surface layer formed; the first surface layer slurry and the second surface layer slurry independently comprise the following components in parts by mass: 1 part of silica sol, 2 - 4 parts of mullite powder; successively applying a first back layer slurry, sanding the first back layer, hardening, applying a second back layer slurry, sanding the second back layer, hardening, applying a third back layer slurry, sanding the third back layer, hardening, applying a fourth back layer slurry, sanding the fourth back layer, hardening, applying a fifth back layer slurry, sanding the fifth back layer, and hardening to obtain a shell with a back layer formed; the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry, and the fifth back layer slurry independently comprise the following components in parts by mass: 1 part of silica sol, 2 - 3.5 parts of white fused alumina powder; when sanding the first back layer and the second back layer, the sand material at the transition R is 20 - 80 mesh chilled iron sand, and the sand material at the remaining parts is 20 - 80 mesh white fused alumina sand; when sanding the third back layer, the fourth back layer, and the fifth back layer, the sand material at the transition R is 20 mesh chilled iron sand, and the sand material at the remaining parts is 20 mesh white fused alumina sand; subjecting the shell with the back layer formed to seal slurry and then hardening it.

[0020] By changing the material of the shell, replacing the chilled iron with chilled iron sand at the transition R, accelerating the heat dissipation of the transition R, changing the local heat dissipation condition at the transition R, making it solidify prior to the flange, avoiding the shrinkage porosity defect at the transition R, and thereby improving the qualified rate of the product. Brief Description of the Drawings

[0021] Figure 1 is a flowchart of the method for avoiding shrinkage porosity at the transition R of equiaxed crystal blades according to the present invention;

[0022] Figure 2 is a physical diagram of the transition R of the shell prepared in Comparative Example 1;

[0023] Figure 3 is a physical diagram of the transition R of the shell prepared in Comparative Example 2;

[0024] Figure 4 is a physical diagram of the transition R of the shell prepared in Comparative Example 3;

[0025] Figure 5 is a physical diagram of the transition R of the shell prepared in Comparative Example 4;

[0026] Figure 6 is a physical diagram of the transition R of the shell prepared in Example 1. Detailed Description of the Embodiments

[0027] The present invention provides a method for avoiding shrinkage porosity at the fillet R of equiaxed crystal blades, comprising the following steps:

[0028] Perform pretreatment on the wax pattern to obtain a pretreated wax pattern;

[0029] Apply the first surface layer slurry, sprinkle sand on the first surface layer, harden, apply the second surface layer slurry, and sprinkle sand on the second surface layer to the pretreated wax pattern in sequence to obtain a shell mold with a formed surface layer; the first surface layer slurry and the second surface layer slurry independently comprise the following components in parts by mass: 1 part of silica sol, 2 - 4 parts of mullite powder;

[0030] Apply the first back layer slurry, sprinkle sand on the first back layer, harden, apply the second back layer slurry, sprinkle sand on the second back layer, harden, apply the third back layer slurry, sprinkle sand on the third back layer, harden, apply the fourth back layer slurry, sprinkle sand on the fourth back layer, harden, apply the fifth back layer slurry, sprinkle sand on the fifth back layer, and harden to the shell mold with the formed surface layer in sequence to obtain a shell mold with a formed back layer; the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry, and the fifth back layer slurry independently comprise the following components in parts by mass: 1 part of silica sol, 2 - 3.5 parts of white fused alumina powder; when sprinkling sand on the first back layer and the second back layer, the sand material at the fillet R is 20 - 80 mesh chills sand, and the sand material at the remaining parts is 20 - 80 mesh white fused alumina sand; when sprinkling sand on the third back layer, the fourth back layer, and the fifth back layer, the sand material at the fillet R is 20 mesh chills sand, and the sand material at the remaining parts is 20 mesh white fused alumina sand;

[0031] Seal the shell mold with the formed back layer and then harden it.

[0032] In the present invention, unless otherwise specified, the raw materials used are commercially available products in the art.

[0033] Figure 1 It is a flow chart of the method for avoiding shrinkage porosity at the fillet R of equiaxed crystal blades according to the present invention.

[0034] The present invention performs pretreatment on the wax pattern to obtain a pretreated wax pattern.

[0035] In the present invention, the pretreatment is preferably to remove the oil stain on the surface of the wax pattern using a wax mold cleaning agent to improve the ability of the coating to wet the surface of the wax pattern.

[0036] After obtaining the pretreated wax pattern, the present invention applies the first surface layer slurry, sprinkles sand on the first surface layer, hardens, applies the second surface layer slurry, and sprinkles sand on the second surface layer to the pretreated wax pattern in sequence to obtain a shell mold with a formed surface layer; the first surface layer slurry and the second surface layer slurry independently comprise the following components in parts by mass: 1 part of silica sol, 2 - 4 parts of mullite powder.

[0037] In the present invention, the mullite powder is preferably 320 mesh.

[0038] In the present invention, the viscosity is measured with a No. 4 coating cup, and the viscosities of the first surface layer slurry and the second surface layer slurry are independently preferably 70 to 100 s.

[0039] In the present invention, the first surface layer slurry and the second surface layer slurry preferably independently further comprise a penetrant and / or an antifoaming agent.

[0040] Based on the mass parts of the silica sol, the mass parts of the penetrant in the first surface layer slurry and the second surface layer slurry are independently preferably 0 to 0.005 parts, more preferably 0.002 to 0.004 parts.

[0041] In the present invention, the penetrant is preferably fatty alcohol polyoxyethylene ether.

[0042] Based on the mass parts of the silica sol, the mass parts of the antifoaming agent in the first surface layer slurry and the second surface layer slurry are independently preferably 0 to 0.005 parts, more preferably 0.002 to 0.004 parts.

[0043] In the present invention, the antifoaming agent is preferably n-octanol.

[0044] In the present invention, the compositions of the first surface layer slurry and the second surface layer slurry are preferably the same.

[0045] In the present invention, the pre-treatment wax film is completely immersed in the first surface layer slurry, and then the wax mold is taken out of the first surface layer slurry and slowly rotated so that the entire surface of the wax mold is evenly coated with the surface layer slurry. After no surface layer slurry flows, the first surface layer sanding is uniformly carried out, and then similar subsequent steps are carried out.

[0046] In the present invention, the sand materials for the first surface layer sanding and the second surface layer sanding are preferably both 80-mesh white fused alumina sand to ensure the surface quality and strength of the shell surface layer.

[0047] After obtaining the shell mold for forming the surface layer, the shell mold for forming the surface layer of the present invention is successively coated with the first back layer slurry, the first back layer sand sprinkling, hardened, coated with the second back layer slurry, the second back layer sand sprinkling, hardened, the third back layer slurry, the third back layer sand sprinkling, hardened, coated with the fourth back layer slurry, the fourth back layer sand sprinkling, hardened, the fifth back layer slurry, the fifth back layer sand sprinkling and hardened to obtain the shell mold for forming the back layer; the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry independently comprise the following components in parts by mass: 1 part of silica sol and 2 - 3.5 parts of white fused alumina powder; when performing the first back layer sand sprinkling and the second back layer sand sprinkling, the sand material at the transition R is 20 - 80 mesh chillsand, and the sand material at the remaining parts is 20 - 80 mesh white fused alumina sand; when performing the third back layer sand sprinkling, the fourth back layer sand sprinkling and the fifth back layer sand sprinkling, the sand material at the transition R is 20 mesh chillsand, and the sand material at the remaining parts is 20 mesh white fused alumina sand.

[0048] In the present invention, the particle size of the chillsand in the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry is preferably 46 - 60 mesh, and the particle size of the white fused alumina sand is preferably 46 - 60 mesh.

[0049] In the present invention, the white fused alumina powder is preferably 320 mesh.

[0050] In the present invention, the viscosity is measured with a No. 4 coating cup, and the viscosities of the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry are independently preferably 30 - 50 s.

[0051] In the present invention, the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry independently preferably further comprise a penetrant and / or an antifoaming agent.

[0052] Based on the mass part of the silica sol, the mass part of the penetrant in the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry is independently preferably 0 - 0.005 part, and more preferably 0.002 - 0.004 part.

[0053] In the present invention, the penetrant is preferably fatty alcohol polyoxyethylene ether.

[0054] Based on the mass part of the silica sol, the mass part of the antifoaming agent in the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry is independently preferably 0 - 0.005 part, and more preferably 0.002 - 0.004 part.

[0055] In the present invention, the antifoaming agent is preferably n - octanol.

[0056] In the present invention, the compositions of the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry are preferably the same.

[0057] In the present invention, the shell for forming the surface layer is completely immersed in the first back layer slurry, then the shell is taken out from the first back layer slurry and slowly rotated, then a layer of cotton is placed at the transition R. After no back layer slurry flows, white fused alumina sand with a mesh size of 20 - 80 is evenly scattered, the cotton at the transition R is removed, and cold iron sand with a mesh size of 20 - 80 is evenly scattered here, and then similar subsequent steps are carried out.

[0058] In the present invention, the thickness of the cotton is preferably 5 - 20 mm.

[0059] In the present invention, the materials of the 20 - 80 mesh cold iron sand and the 20 mesh cold iron sand are preferably independently a metal material or a non - metal material. The metal material preferably includes cast iron and / or stainless steel, and the non - metal material preferably includes one or more of iron oxide, silica sand and chromite sand.

[0060] In the present invention, the function of the cold iron sand is to accelerate heat dissipation, and it has the characteristics of high temperature resistance and good thermal conductivity. In the present invention, by changing the material of the shell transition R and setting different mesh numbers, while ensuring the strength of the shell, the purpose of accelerating heat dissipation of the transition R is achieved.

[0061] After obtaining the shell for forming the back layer, the present invention seals and hardens the shell for forming the back layer.

[0062] In the present invention, the slurry for sealing is preferably the same as the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry in composition, which will not be elaborated here.

[0063] In the present invention, the hardening is preferably drying and hardening for more than 4 h in a constant temperature and humidity environment, and the time is more preferably 6 - 8 h. The temperature of the constant temperature and humidity environment is preferably 18 - 25 °C, and the humidity is preferably 30 - 70%.

[0064] To further illustrate the present invention, the following examples are used to describe in detail the method for avoiding porosity at the transition R of equiaxed crystal blades provided by the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0065] Example 1

[0066] Surface layer slurry: By weight, 1 part of silica sol, 3 parts of 320 - mesh mullite powder, 0.005 part of penetrant fatty alcohol polyoxyethylene ether, 0.005 part of defoamer n - octanol. Its viscosity is measured with a No. 4 coating cup, and the viscosity is 80 s. Surface layer sand: 80 - mesh white fused alumina sand

[0067] Backing layer slurry: By weight, 1 part of silica sol, 3.5 parts of white fused alumina powder of 320 mesh, 0.005 part of penetrant fatty alcohol polyoxyethylene ether, 0.005 part of defoamer n-octanol. Its viscosity is measured with a No. 4 coating cup and the viscosity is 30 s.

[0068] Backing layer sand: White fused alumina sand of 46 mesh, white fused alumina sand of 20 mesh, chills sand of 46 mesh, chills sand of 20 mesh. In particular, the chills sand is magnetite.

[0069] (1) Pretreatment

[0070] Use a wax mold cleaning agent to remove the oil stain on the surface of the wax mold.

[0071] (2) Coating the shell surface layer

[0072] Completely immerse the wax mold group in step (1) in the surface layer slurry, then take out the wax mold group from the slurry and slowly rotate it so that the entire surface of the wax mold group is evenly coated with the surface layer slurry. After there is no surface layer slurry flowing, evenly sprinkle sand, and then place it in a constant temperature and humidity environment for drying and hardening for 4 h. Repeat this process twice to obtain a shell with two surface layers.

[0073] (3) Coating the shell backing layer

[0074] Completely immerse the shell in step (2) in the backing layer slurry, then take out the shell from the slurry and slowly rotate it so that the entire surface of the shell is evenly coated with the backing layer slurry. Then place cotton (thickness 5 mm) at the transition R. After there is no backing layer slurry flowing, evenly sprinkle sand, remove the cotton at the transition R, evenly sprinkle chills sand here, and then place it in a constant temperature and humidity environment for drying and hardening for 6 h. Repeat this process five times to obtain a shell with five backing layers.

[0075] For the first two backing layer sands, white fused alumina sand of 46 mesh is used, and chills sand of 46 mesh is used at the transition R; for the last three backing layer sands, white fused alumina sand of 20 mesh is used, and chills sand of 20 mesh is used at the transition R.

[0076] (4) Sealing slurry

[0077] Completely immerse the shell in step (3) in the backing layer slurry, then take out the shell from the slurry and slowly rotate it so that the entire surface of the wax mold group is evenly coated with the backing layer slurry, and then place it in a constant temperature and humidity environment for drying and hardening for 8 h.

[0078] Figure 6 It is a physical picture of the transition R of the shell obtained in Example 1.

[0079] Comparative Example 1

[0080] The preparation method of the shell is the same as that of Example 1, and the differences are shown in Table 1.

[0081] Figure 2 It is a physical diagram of the R transition of the shell prepared in Comparative Example 1.

[0082] Comparative Example 2

[0083] The preparation method of the shell is the same as that in Example 1, and the differences are shown in Table 1.

[0084] Figure 3 It is a physical diagram of the R transition of the shell prepared in Comparative Example 2.

[0085] Comparative Example 3

[0086] The preparation method of the shell is the same as that in Example 1, and the differences are shown in Table 1.

[0087] Figure 4 It is a physical diagram of the R transition of the shell prepared in Comparative Example 3.

[0088] Comparative Example 1

[0089] The preparation method of the shell is the same as that in Example 1, and the differences are shown in Table 1

[0090] Figure 5 It is a physical diagram of the R transition of the shell prepared in Comparative Example 4.

[0091] Table 1 Comparison between Examples and Comparative Examples

[0092]

[0093] As can be seen from Table 1, by changing the local heat dissipation condition of the shell, the present invention accelerates the solidification of the R transition part, avoids the looseness of the casting at the R transition, solves the problem of looseness defects at the hot spot of the casting, and improves the qualified rate of the product.

[0094] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for avoiding equiaxed crystal blade transition R porosity, characterized in that, It includes the following steps: Perform pretreatment on the wax film to obtain a pretreated wax film; Successively apply the first surface layer slurry, first surface layer sanding, hardening, apply the second surface layer slurry and second surface layer sanding to the pretreated wax film to obtain a shell mold with a surface layer formed; the first surface layer slurry and the second surface layer slurry independently include the following components in parts by mass: 1 part of silica sol, 2-4 parts of mullite powder; Successively apply the first back layer slurry, first back layer sanding, hardening, apply the second back layer slurry, second back layer sanding, hardening, third back layer slurry, third back layer sanding, hardening, apply the fourth back layer slurry, fourth back layer sanding, hardening, fifth back layer slurry, fifth back layer sanding and hardening to the shell mold with the surface layer formed to obtain a shell mold with a back layer formed; the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry independently include the following components in parts by mass: 1 part of silica sol, 2-3.5 parts of white corundum powder; when performing the first back layer sanding and the second back layer sanding, the sand material at the transition R is 46-mesh chilled iron sand, and the sand material at the remaining parts is 46-mesh white corundum sand; when performing the third back layer sanding, the fourth back layer sanding and the fifth back layer sanding, the sand material at the transition R is 20-mesh chilled iron sand, and the sand material at the remaining parts is 20-mesh white corundum sand; Perform post-curing after sealing the shell mold with the back layer formed.

2. The method according to claim 1, characterized in that, The particle sizes of both the mullite powder and the white corundum powder are 320 mesh.

3. The method according to claim 1, wherein The first surface layer slurry and the second surface layer slurry independently further include a penetrant and / or an antifoaming agent.

4. The method according to claim 1 or 3, characterized in that Measure the viscosity with a No. 4 coating cup, and the viscosities of the first surface layer slurry and the second surface layer slurry are independently 70-100 s.

5. The method according to claim 1, wherein The first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry independently further include a penetrant and / or an antifoaming agent.

6. The method according to claim 1 or 5, characterized in that Measure the viscosity with a No. 4 coating cup, and the viscosities of the first back layer slurry, the second back layer slurry, the third back layer slurry, the fourth back layer slurry and the fifth back layer slurry are independently 30-50 s.

7. The method according to claim 1, characterized in that, The materials of the 46-mesh chilled iron sand and the 20-mesh chilled iron sand are independently a metal material or a non-metal material. The metal material includes cast iron and / or stainless steel, and the non-metal material includes one or more of ferric oxide, silica sand and chromite sand.

8. The method according to claim 1, characterized in that, The sand materials for the first surface layer sanding and the second surface layer sanding are both 80-mesh white corundum sand.

9. The method according to claim 1, wherein The slurry for sealing includes the following components in parts by mass: 1 part of silica sol, 2-3.5 parts of white corundum powder.

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