Method for eliminating looseness defect of tip shroud at inclination angle

Abstract

The invention relates to a method for eliminating the looseness defect of the shroud position of a turbine blade and a wax mold module, and belongs to the technical field of turbine blade casting. The method comprises the steps that S1, a blade wax mold is prepared, the blade wax mold comprises a crystal selection section, a blade crown, a blade body and a tenon which are integrally formed and sequentially connected, and a groove is formed in the connecting position of the crystal selection section and the blade crown along the contour shape of the blade crown; s2, a plurality of blade wax molds are assembled to form a wax mold module; s3, the wax mold module is adopted for preparing a pouring mold shell, and a blocking protrusion is formed in the position, corresponding to the groove of the blade wax mold, of the inner surface of the pouring mold shell; s4, the pouring mold shell and the inner cavity mold core are assembled to form a pouring module, and a crystal selection growth channel is formed between the pouring mold shell blocking protrusion and the inner cavity mold core; and S5, molten metal is poured into the pouring module, crystal selection growth of the molten metal is started from the tip crown end through directional solidification, and the turbine blade with the tip crown free of the loosening defect is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of turbine blade casting, and in particular to a method for eliminating loose defects of a blade crown at an inclined angle and a wax mold module. Background Art

[0002] As the direct power component of an aircraft, aircraft engines determine the stability and economy of an aircraft. With the development trend of high power and low fuel consumption of large thrust-to-weight ratio aircraft engines, and the continuous increase in the engine turbine inlet temperature, the design of aircraft engines has become more and more complex. As a key component at the hot end of an aircraft engine, the operating temperature of turbine blades is also constantly increasing, and more designs of turbine blades have appeared. Among them, the crown structure of low-pressure turbines and power turbine components is the most common. However, this blade crown structure is prone to loose defects due to insufficient shrinkage compensation during the casting process, resulting in unqualified turbine blades. Summary of the invention

[0003] In view of the above analysis, the embodiments of the present invention aim to provide a method for eliminating the loose defect of the blade crown at an inclined angle and a wax mold module, so as to solve the problem that the blade crown position of the hollow blade is prone to loose defects due to insufficient shrinkage compensation.

[0004] In one aspect, an embodiment of the present invention provides a method for eliminating a loose defect in a turbine blade shroud position, comprising:

[0005] Step S1, preparing a blade wax mold, the blade wax mold comprising a crystal selection section, a blade crown, a blade body, and a tenon which are integrally formed and connected in sequence, and a groove is formed at the connection between the crystal selection section and the blade crown along the contour of the blade crown;

[0006] Step S2, assembling a plurality of blade wax models to form a wax model module, in which a plurality of blade wax models are distributed in a circumferential direction around the center of the wax model module;

[0007] Step S3, using the wax mold assembly to prepare a casting shell, so that a blocking protrusion is formed at a corresponding position between the inner surface of the casting shell and the groove of the blade wax mold;

[0008] Step S4, assembling the casting shell and the inner cavity core to form a casting module, and forming a crystal selection growth channel between the blocking protrusion of the casting shell and the inner cavity core;

[0009] Step S5, pouring molten metal into the casting mold, and making the molten metal start to grow from the blade crown end through directional solidification, so as to prepare a hollow shrouded turbine blade with no loose defects in the blade crown.

[0010] Furthermore, in step S1, when preparing the blade wax mold, the distance between the bottom of the groove and the inner cavity core is controlled to be 0.5-1 mm, so that the width of the selective crystal growth channel is 0.5-1 mm.

[0011] Furthermore, the blade crown is tilted relative to the blade body; in step S2, when assembling the wax mold module, the edge of the highest solidification point of the blade crown is directed toward the center of the wax mold module and forms an angle with the radial direction of the wax mold module, and a shrinkage compensation wax block is set next to the edge of the highest solidification point of the blade crown.

[0012] Furthermore, when assembling the wax mold assembly, the edge of the highest solidification point of the blade crown is oriented toward the center of the wax mold assembly, and the angle between the radial line connecting the edge and the center of the wax mold assembly and the edge itself is 45°.

[0013] Furthermore, in step S1, when preparing the wax mold of the blade, a portion of the edge of the highest solidification point of the blade crown close to the center of the wax mold module is continued to be extended outward along the inclination direction of the blade crown and raised, and the raised edge is continued to be extended outward in the horizontal direction to form a shrinkage-feeding platform of a predetermined width; in step S2, when assembling the wax mold module, the shrinkage-feeding wax block is set on the shrinkage-feeding platform.

[0014] Further, in step S2, when assembling the wax model module, a feeding wax block is bonded on the feeding platform, the feeding wax block is a rectangular parallelepiped, the feeding wax block and the feeding platform are vertically arranged, and the bonding surface of the feeding wax block matches the size of the feeding platform.

[0015] Furthermore, in step S2, when assembling the wax mold module, a heat-insulating wax mold sleeve is arranged in the space formed by the plurality of blade wax molds, so that the heat-insulating wax mold sleeve is located at the center of the wax mold module and is spaced apart from the blade wax molds.

[0016] Furthermore, the distance between the outer surface of the insulating wax mold sleeve and the shrinkage feeding wax block of the blade crown is maintained at 25-30 mm, and the upper surface of the insulating wax mold sleeve is higher than the shrinkage feeding wax block by no less than 20 mm.

[0017] Furthermore, in step S5, the casting mold is placed in a heating device, and when the casting mold reaches a predetermined temperature and is kept warm, the molten metal is poured into the casting mold; the casting mold is pulled out and separated from the heating device so that the molten metal starts to directionally solidify from the blade crown end, and the pulling rate is controlled to be 3 to 5 mm / min.

[0018] On the other hand, an embodiment of the present invention also provides a wax mold module for eliminating the loose defects of blade crowns at inclined angles, which includes: a pouring gate, an upper runner, multiple blade wax molds, an insulating wax mold sleeve, and a base; the pouring gate is connected to the upper runner, the upper runner and the base are spaced apart, and multiple blade wax molds are connected between the upper runner and the base; the insulating wax mold sleeve is connected to the base, and the pouring gate, the upper runner, the insulating wax mold sleeve and the base are concentrically arranged; multiple blade wax molds are evenly arranged around the insulating wax mold sleeve; wherein the blade wax mold includes a crystal selection section, a blade crown, a blade body and a tenon connected in sequence, the crystal selection section is connected to the base, and the tenon is connected to the upper runner; a groove is provided at the connection between the crystal selection section and the blade crown along the contour shape of the blade crown.

[0019] Compared with the prior art, the method of the present invention can achieve at least one of the following beneficial effects:

[0020] 1. The blade of the present invention starts to grow by crystal selection from the blade crown end during the directional solidification process, and when preparing the blade wax mold, a groove is set along the blade crown contour shape at the connection between the crystal selection section and the blade crown, so that the inner surface of the casting shell prepared by the blade wax mold forms a blocking protrusion at the position corresponding to the groove, so as to block the shrinkage of the blade crown body to the crystal selection runner below it when the molten metal in the shell is directional solidified, thereby reducing the degree of looseness of the blade crown. In addition, the blocking protrusion is set at the crystal selection runner, which will not affect or change the structure of the turbine blade itself formed by casting.

[0021] 2. The present invention controls the distance between the bottom of the groove at the connection between the crystal selection section and the blade crown and the inner cavity core to be 0.5-1 mm, so that a crystal selection growth channel with extremely small width is formed between the barrier protrusion on the inner surface of the shell and the inner cavity core, ensuring that the grains can grow smoothly from the crystal selection runner to the blade body to prepare hollow blades; at the same time, the shrinkage of the blade crown body to the crystal selection runner is blocked.

[0022] 3. The present invention directs the highest solidification point edge of the inclined blade crown toward the center of the wax mold module and forms an angle between the edge and the radial direction of the wax mold module, so that the projection of the edge in the radial direction of the wax mold module has a certain distance, so that the radial temperature gradient of the casting module can be utilized during directional solidification to make the edge of the blade crown solidify and shrink sequentially in the radial direction, and a shrinkage compensation block is set at the last solidification position to effectively compensate the shrinkage of the blade crown, thereby further eliminating the looseness defect of the blade crown.

[0023] 4. The present invention arranges an insulating wax mold sleeve at the center of the wax mold module, so that a cylindrical ceramic shell insulation layer is formed in the central area of ​​the casting module. In the subsequent directional solidification process of the molten metal in the shell, the radial heat dissipation is blocked, and the cooling rate of the central area of ​​the casting module is slowed down, thereby increasing the temperature gradient in the radial direction of the casting module, which is beneficial for the blade crown to solidify sequentially in the direction of the radial temperature gradient and complete shrinkage compensation, so as to eliminate the loose defects of the blade crown and improve the casting qualification rate of the turbine blade with the inclined angle blade crown structure.

[0024] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0026] Figure 1 Schematic diagram of the structure of the blade wax mold of some embodiments of the present invention.

[0027] Figure 2 yes Figure 1 A partial enlarged view of the crown of the blade wax model.

[0028] Figure 3 Schematic diagram of the structure of the leaf crown of some embodiments of the present invention.

[0029] Figure 4 It is a schematic diagram of the structure of the wax model module of some embodiments of the present invention.

[0030] Figure 5 yes Figure 4 Schematic diagram of the partial structure of the middle wax model module.

[0031] Figure 6 Schematic diagram of the cross section of a wax mold assembly according to some embodiments of the present invention.

[0032] Figure 7 This is a partial photo of the leaf crown prepared in Example 1 of the present invention.

[0033] Figure 8 This is a partial photo of the leaf crown prepared in Comparative Example 1 of the present invention.

[0034] Description of reference numerals:

[0035] 10. Blade wax mold; 11. Crystal selection section; 12. Blade crown; 13. Blade body; 14. Tenon; 15. Groove; 16. Core positioning hole; 17. Extension section; 18. Shrinkage feeding platform; 20. Shrinkage feeding wax block; 30. Base; 40. Insulation wax mold sleeve; 50. Pouring gate; 60. Upper runner. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0037] The turbine blade includes a tenon, a blade body, and a blade crown connected in sequence, wherein the tenon is used to connect to the turbine, and the blade crown is arranged at the end of the blade body away from the turbine. The blade crown is inclined relative to the blade body. When casting the turbine blade, the blade crown has a certain inclination angle with the horizontal direction. This structure is conducive to the longitudinal shrinkage compensation of the blade crown during directional solidification. However, a certain edge of the blade crown with an inclined angle must be at the highest point in the longitudinal direction, making it easy to have loose defects during directional solidification.

[0038] To this end, an embodiment of the present invention provides a method for eliminating the loose defect at the shroud position of a turbine blade, so as to eliminate the loose defect at the shroud position and improve the casting qualification rate of the turbine blade. The method for eliminating the loose defect at the shroud position of a turbine blade according to an embodiment of the present invention comprises the following steps:

[0039] Step S1, prepare a blade wax model, such as Figure 1 As shown, the blade wax mold 10 includes an integrally formed crystal selection section 11, a blade crown 12, a blade body 13, and a tenon 14 that are sequentially connected. A groove 15 is formed along the contour of the blade crown 12 at the connection between the crystal selection section 11 and the blade crown 12;

[0040] Step S2, assembling a plurality of blade wax models 10 to form a wax model module, in which the plurality of blade wax models 10 are distributed in a circumferential direction around the center of the wax model module;

[0041] Step S3, using the wax mold assembly to prepare a casting shell, so that a blocking protrusion is formed at a corresponding position between the inner surface of the casting shell and the groove of the blade wax mold;

[0042] Step S4, assembling the casting shell and the inner cavity core to form a casting module, and forming a crystal selection growth channel between the blocking protrusion of the casting shell and the inner cavity core;

[0043] Step S5, pouring molten metal into the casting mold, and causing the molten metal to selectively grow from the blade crown end through directional solidification, so as to prepare a hollow shrouded turbine blade with no loose defects in the blade crown.

[0044] Using the method of the embodiment of the present invention, such as Figure 1As shown, when preparing the blade wax mold 10 in step S1, the crystal selection section 11 is set at the end of the blade crown 12 away from the blade body 13, so that the crystal selection runner in the casting shell prepared using the blade wax mold 10 is adjacent to the blade crown structure of the blade itself, so that the blade starts to grow by crystal selection from the blade crown end during the directional solidification process.

[0045] like Figure 1 and Figure 2 As shown, when preparing the blade wax mold 10, the present invention sets a groove 15 along the contour of the blade crown 12 at the connection between the crystal selection section 11 and the blade crown 12, so that the inner surface of the casting shell prepared by the blade wax mold 10 forms a blocking protrusion at the position corresponding to the groove 15, so that the thickness of the crystal selection runner of the shell is reduced at this position, so as to block the shrinkage of the blade crown body to the crystal selection runner below it when the molten metal in the shell is directionally solidified, thereby reducing the degree of looseness of the blade crown. In addition, the blocking protrusion is set at the crystal selection runner, which will not affect or change the structure of the turbine blade itself formed by casting.

[0046] It should be noted that the blade prepared in the present invention is a hollow blade. In order to form the inner cavity of the hollow blade, the casting shell and the inner cavity core are assembled to form a casting module, so that when the molten metal is poured, the molten metal is filled between the casting shell and the inner cavity core, and the blade cavity is formed at the position of the inner cavity core, so as to cast a hollow blade.

[0047] In step S2, a wax mold set is assembled using the blade wax mold 10. Figure 4 and Figure 5 As shown, the wax mold assembly includes a plurality of blade wax molds 10, a pouring gate 50, an upper runner 60 and a base 30. When assembling the wax mold assembly, the plurality of blade wax molds 10 are arranged between the base 30 and the upper runner 60 along the circumferential direction of the base 30 (only one of the blade wax molds 10 is shown in the figure), the crystal selection section 11 of the blade wax mold 10 is connected to the base 30, the tenon 14 is connected to the upper runner 60, the pouring gate 50 is connected to the upper runner 60, and the pouring gate 50, the upper runner 60 and the base 30 are arranged concentrically.

[0048] Furthermore, in step S3, when the wax mold set is used to prepare the casting shell, a cavity consistent with the structure and size of the wax mold set can be formed in the casting shell, and then a turbine blade consistent with the structure of the blade wax mold 10 can be obtained by casting. In addition, the cavity in the casting shell includes, from bottom to top, interconnected crystal selection runners, blade crown cavity, blade body cavity, etc., so that after pouring molten metal, the blade grows from the crystal selection runner to the blade crown, blade body, and tenon in sequence to prepare the blade.

[0049] Furthermore, in order to prepare a hollow turbine blade with a crown, in step S4, a casting mold is assembled with the inner cavity core to form a casting mold group, and a cavity is formed between the casting mold shell and the inner cavity core. Since a groove 15 is formed at the connection between the crystal selection section 11 of the blade wax mold 10 and the blade crown 12, and a blocking protrusion is formed at a corresponding position on the inner surface of the casting mold shell, when the casting mold shell and the inner cavity core are assembled, the top area of ​​the crystal selection runner formed can block the upper blade crown body from compensating for the crystal selection runner during the directional solidification process due to the setting of the blocking protrusion, thereby reducing the looseness defect of the blade crown.

[0050] In some embodiments, in step S1, when preparing the blade wax mold 10, the distance between the bottom of the groove 15 and the inner cavity core is controlled to be 0.5-1 mm, so that the width of the selective crystal growth channel is 0.5-1 mm.

[0051] In order to prevent the blocking protrusion on the inner surface of the casting shell from completely blocking the connection between the crystal selection runner and the blade crown shell above it, the embodiment of the present invention makes a very small gap between the bottom of the groove 15 and the inner cavity core when preparing the blade wax mold 10, that is, a very small gap is made between the blocking protrusion of the casting shell and the inner cavity core to form a crystal selection growth channel, which can not only block the shrinkage of the blade crown body to the crystal selection runner, but also ensure that the grains in the crystal selection runner can smoothly grow to the blade crown and the blade body through the gap. If the distance is too large, it is difficult to block the shrinkage of the blade crown to the crystal selection runner; if the distance is too small, it is difficult for the grains to grow smoothly from the crystal selection runner to the blade crown.

[0052] In addition, for solid blades, when preparing the blade wax mold 10, a groove 15 can also be set at the connection between the crystal selection section 11 and the blade crown 12, and the distance between the bottoms of the grooves 15 on the opposite sides of the crystal selection section is 0.5 to 1 mm, so that a crystal selection growth channel with a thickness of 0.5 to 1 mm is formed at the corresponding position in the casting shell through the opposite blocking protrusions on both sides, which can block the shrinkage of the blade crown to the crystal selection runner, and at the same time ensure that the grains can grow smoothly from the crystal selection runner to the blade body.

[0053] In some embodiments, when preparing the blade wax mold 10, molten paraffin can be injected into the mold and solidified to form the blade wax mold 10. In order to obtain the blade wax mold 10 of the above structure, when designing the mold, a groove cutting portion protruding from the mold surface is designed along the contour shape of the blade crown at the connection between the crystal selection section and the blade crown, and then the blade wax mold 10 with the groove 15 is formed by pressing the groove cutting portion.

[0054] In some embodiments, when preparing the blade wax mold 10, symmetrical positioning protrusions can be set on the inner surface of the mold at positions corresponding to the crystal selection sections, and the inner cavity core can be fixedly clamped inside the mold by the positioning protrusions on both sides. This ensures that the relative position between the blade wax mold 10 and the inner cavity core is maintained when preparing the blade wax mold 10, so as to facilitate positioning of the casting shell and the inner cavity core when preparing the casting shell.

[0055] At the same time, the distance between the bottom of the groove 15 of the blade wax model 10 and the inner cavity core is ensured by controlling the height of the groove cutting line in the mold. For example, by controlling the height of the groove cutting part in the mold to be 0.5 to 1 mm lower than the height of the positioning protrusion, the distance between the bottom of the groove of the blade wax model 10 and the inner cavity core is ensured to be 0.5 to 1 mm.

[0056] Furthermore, if Figure 1 and Figure 2 As shown, since the positioning protrusion is provided in the mold, the crystal selection section of the blade wax mold 10 is formed with a core positioning hole 16, and the core positioning hole 16 is located on the side of the groove 15 away from the blade body 13. The present invention provides the core positioning hole 16, and can form a core positioning protrusion on the inner surface of the casting shell when preparing the casting shell, and the two sides of the inner cavity core are positioned by the core positioning protrusion, so as to avoid the thickness of the hollow blade formed by casting being inconsistent on both sides of the inner cavity core.

[0057] For example, two groups of core positioning holes 16 may be provided, and the two groups of core positioning holes 16 are symmetrically and evenly distributed on both sides of the blade wax mold, and the diameter of the core positioning holes 16 may be 2-3 mm.

[0058] In some embodiments, after the blade wax mold 10 is prepared, the blade wax mold 10 is trimmed, and a paraffin layer of a certain thickness is applied to the bottom of the core positioning hole 16, so that the core positioning protrusion on the inner surface of the casting shell and the inner cavity core have a certain gap. During the heating and cooling process of casting turbine blades, when the casting shell and the inner cavity core change in size inconsistently due to thermal expansion and contraction, there is a certain activity space between the two to avoid contact deformation and fracture. For example, the thickness of the paraffin layer at the bottom of the core positioning hole 16 can be 0.1 to 0.2 mm.

[0059] In some embodiments, Figure 3 As shown, the blade crown 12 is approximately a parallelogram, wherein two opposite edges are serrated.

[0060] Since the blade crown 12 is tilted relative to the blade body 13, one side edge of the blade crown 12 is at the highest solidification point. In step S2, when assembling the wax mold module, the edge of the highest solidification point of the blade crown 12 is oriented toward the center of the wax mold module and forms an angle with the radial direction of the wax mold module, and a feeding wax block is arranged next to the edge of the highest solidification point of the blade crown 12, so that the feeding wax mold is located at a position of the blade crown 12 close to the center of the wax mold module.

[0061] Specifically, Figure 4 and Figure 5 As shown, the edge of the highest solidification point of the leaf crown 12 faces the center of the wax mold module, and a shrinkage wax block 20 is arranged next to the edge; Figure 6 As shown, the edge of the highest solidification point of the blade crown 12 forms an angle with the radial direction of the wax mold module, so that the projection of the edge in the radial direction of the wax mold module has a certain distance.

[0062] The present invention directs the edge of the highest solidification point of the blade crown 12 toward the center of the wax mold module and forms an angle with the radial direction of the wax mold module, so that the edge is not perpendicular to the radial direction of the wax mold module, and the projection of the edge in the radial direction of the wax mold module has a certain distance, so that during directional solidification, the radial temperature gradient of the casting module is used to make the edge of the blade crown solidify in radial sequence, thereby completing the effective sequential shrinkage compensation of the blade crown; at the same time, a shrinkage compensation wax block is arranged at the last solidification position, so that a shrinkage compensation block is formed in the casting module at the last solidification position of the blade crown, so that the shrinkage compensation block is located near the center of the casting module, so as to effectively compensate the edge of the highest solidification point of the blade crown, and at the same time, the vertical design of the rectangular-shaped shrinkage compensation block also exerts the radial heat insulation effect of the shrinkage compensation block, thereby improving the radial temperature gradient of the blade crown structure and ensuring the radial sequential solidification of the blade crown.

[0063] In some embodiments, when assembling the wax mold module, the angle between the radial line connecting the edge of the highest solidification point of the blade crown and the center of the wax mold module and the edge itself is 45°, so that the projection length of the edge on the radial line is longer, thereby increasing the temperature gradient between the end point of the edge of the blade crown far from the center of the module and the end point close to the center of the module during directional solidification, so that the edge solidifies and shrinks sequentially in the direction of the temperature gradient, thereby reducing the looseness defect of the blade crown.

[0064] Specifically, Figure 6 As shown, the angle a between the endpoint of the highest solidification point edge of the leaf crown 12 close to the center of the wax mold module and the edge itself can be 45°; or, the angle b between the endpoint of the highest solidification point edge of the leaf crown 12 away from the center of the wax mold module and the edge itself can be 45°; or, the angle between any point in the middle of the highest solidification point edge of the leaf crown 12 and the edge itself can be 45°.

[0065] In some embodiments, in step S1, when preparing the blade wax mold 10, a portion of the edge of the highest solidification point of the blade crown 12 close to the center of the wax mold module is continued to extend outward along the inclination direction of the blade crown 12 to be raised, and the raised edge is continued to extend outward in the horizontal direction to form a shrinkage-feeding platform of a predetermined width; in step S2, when assembling the wax mold module, the shrinkage-feeding wax block is set on the shrinkage-feeding platform.

[0066] Specifically, Figure 2 and Figure 3 As shown, a portion of the edge of the highest solidification point of the blade crown 12 close to the center of the wax mold module continues to extend along the inclined direction of the blade crown 12 to form an extension section 17, so that the portion of the edge of the blade crown 12 close to the center of the module is raised; after the extension section 17 is formed, the edge of the extension section 17 continues to extend in the horizontal direction away from the blade crown to form a shrinkage platform 18. Figure 2 As shown, the feeding wax block 20 is disposed on the feeding platform 18 .

[0067] The present invention extends and heightens the edge of the blade crown to form an extension section and then sets the feeding platform, so as to avoid the feeding platform directly contacting the edge of the blade crown itself, and to avoid excess molten paraffin flowing to the blade crown when bonding the feeding wax block, thereby affecting the original structure of the blade crown in the blade wax mold, and further affecting the structure of the blade crown in the turbine blade finally obtained. At the same time, the setting of the extension section can also use the feeding runner in the casting shell formed by the extension section to further feed the blade crown, thereby reducing the loose defects of the blade crown.

[0068] In some embodiments, the length of the extension section 17 is 1 / 2 of the length of the edge of the highest solidification point of the blade crown 12, and the width of the extension section 17 along the inclined direction of the blade crown 12 is 2-3 mm. If the width of the extension section 17 is too large, the feeding wax block 20 will not directly feed the blade crown 12 during the subsequent directional solidification; if the width is too small, it is not convenient to fill the molten paraffin when bonding the feeding wax mold 20, and the operation is inconvenient.

[0069] In some embodiments, in step S2, when assembling the wax model module, the feeding wax block 20 is bonded to the feeding platform 18. Figure 1 and Figure 2 As shown, the feeding wax block 20 is a rectangular parallelepiped, the feeding wax block 20 and the feeding platform 18 are vertically arranged, and the bonding surface of the feeding wax block 20 matches the size of the feeding platform 18.

[0070] The embodiment of the present invention adopts a rectangular-shaped feeding wax block, and the feeding wax block is placed close to and along the edge of the highest solidification point of the leaf crown. Compared with feeding blocks of other shapes, the vertically designed rectangular-shaped large-area feeding block plays a radial heat insulation role of the feeding block and has a large volume feeding amount. The highest solidification point edge of the leaf crown can be effectively fed through the feeding block during subsequent directional solidification, thereby improving the feeding effect.

[0071] In some embodiments, the length of the feeding platform 18 is 1 / 2 of the length of the edge of the highest solidification point of the blade crown 12; the width of the feeding platform 18 is 3-4 mm, that is, the thickness of the feeding wax block 20 is 3-4 mm, and the height of the feeding wax block is 15-18 mm. If the thickness or height of the feeding wax block 20 is too small, the feeding effect will be insufficient, and the radial heat insulation effect will be insufficient; if the thickness or height of the feeding wax block 20 is too large, there will be a large stress during the directional solidification shrinkage, causing the blade crown of the turbine blade to deform.

[0072] In some embodiments, when bonding the feeding wax block 20 to the feeding platform 18 and preparing the extension section 17 and the feeding platform 18, molten wax may be used to fill and trim the joints of the adjacent structures after bonding to ensure a smooth transition at the transition position.

[0073] In some embodiments, in step S2, Figure 4 and Figure 5 As shown, when assembling the wax mold module, a heat-insulating wax mold sleeve 40 is arranged in the space formed by a plurality of blade wax molds 10 , so that the heat-insulating wax mold sleeve 40 is located at the center of the wax mold module and is spaced apart from the blade wax mold 10 .

[0074] The present invention arranges an insulating wax mold sleeve 40 in the center of the wax mold module, thereby forming a cylindrical ceramic insulating barrier in the central area of ​​the casting module, blocking radial heat dissipation during directional solidification, slowing down the cooling rate of the central area of ​​the casting module, thereby increasing the temperature gradient in the radial direction of the casting module, which is beneficial to the sequential solidification of the blade crown in the direction of the radial temperature gradient and effective sequential shrinkage compensation.

[0075] It should be noted that the position of the insulating wax mold sleeve 40 in the casting mold forms a cavity after dewaxing, and the cavity and the ceramic mold shell outside it form a ceramic insulating layer, which plays a radial heat insulation role; and because the insulating wax mold sleeve 40 of the present invention is not connected to the upper runner 60 above, the molten metal cannot enter the cavity when pouring the molten metal, thereby avoiding the waste of molten metal.

[0076] In some embodiments, Figure 5As shown, the distance L between the outer surface of the insulating wax mold sleeve 40 and the shrinkage feeding wax block 20 of the blade crown is maintained at 25 to 30 mm, and the upper surface of the insulating wax mold sleeve 40 is higher than the shrinkage feeding wax block 20 by a height H of not less than 20 mm. If the height of the insulating wax mold sleeve 40 is too low or the distance from the shrinkage feeding wax block 20 is too large, the insulating layer will not have a radial heat insulation effect on the shrinkage feeding block during the subsequent directional solidification, resulting in a rapid drop in the temperature of the shrinkage feeding block and a decrease in the radial temperature gradient of the casting module, which is not conducive to the radial sequential solidification and shrinkage feeding of the blade crown along the casting module; if the distance between the insulating wax mold sleeve 40 and the shrinkage feeding wax block 20 is too small, when preparing the casting shell, the shell of the insulating wax mold sleeve 40 and the shrinkage feeding wax block 20 are easy to stick together, affecting the drying of the shell.

[0077] In some embodiments, in step S5, the casting mold is placed in a heating device, and when the casting mold reaches a predetermined temperature and is kept warm, the molten metal is poured into the casting mold; the casting mold is pulled out and separated from the heating device so that the molten metal starts to directionally solidify from the blade crown end, and the pulling rate is controlled to 3 to 5 mm / min.

[0078] The present invention ensures that the inclined blade crown structure can solidify and complete shrinkage compensation in sequence according to the axial and radial temperature gradient directions by selecting a suitable pulling rate. If the pulling rate is too large or too small, it will affect the temperature gradient and solidification sequence of the blade along the axial and radial directions of the casting module during the directional solidification process, and the shrinkage compensation design cannot complete the solidification and shrinkage compensation in sequence according to the axial and radial directions of the casting module.

[0079] The embodiment of the present invention also provides a wax mold module for eliminating the loose defect of the inclined angle blade crown, such as Figure 4 and Figure 5 As shown, the wax mold assembly includes: a pouring port 50, an upper runner 60, a plurality of blade wax molds 10, a heat-insulating wax mold sleeve 40, and a base 30. The pouring port 50 is connected to the upper runner 60, the upper runner 60 and the base 30 are spaced apart, and a plurality of blade wax molds 10 are connected between the upper runner 60 and the base 30; the heat-insulating wax mold sleeve 40 is connected to the base 30, and the pouring port 50, the upper runner 60, the heat-insulating wax mold sleeve 40 and the base 30 are concentrically arranged; a plurality of blade wax molds 10 are evenly arranged around the heat-insulating wax mold sleeve 40; wherein, as shown in FIG. Figure 1 and Figure 2 As shown, the blade wax mold 10 includes a crystal selection section 11, a blade crown 12, a blade body 13 and a tenon 14 which are connected in sequence. The crystal selection section 11 is connected to the base 30, and the tenon 14 is connected to the upper runner 60. A groove 15 extending along the contour shape of the blade crown 12 is provided at the connection between the crystal selection section 11 and the blade crown 12.

[0080] In addition, the structure of the wax mold module is the same as that in the above embodiment and will not be repeated here.

[0081] The method for eliminating the loose defect of the inclined angle blade crown of the present invention is further described below with reference to specific embodiments.

[0082] Example 1

[0083] The method of this embodiment is used to cast turbine working blades with a blade crown structure with an inclined angle. The turbine working blades are hollow blades with crowns. The plane shape of the blade crown is approximately a parallelogram. The sizes of adjacent edges are 30mm and 40mm, and the 40mm long edge is serrated. When the blade crown is placed vertically, the angle between it and the horizontal direction is 40°.

[0084] The method of this embodiment includes:

[0085] S1, prepare a blade wax model 10. Figure 1 As shown, the blade wax mold 10 includes a crystal selection section 11, a blade crown 12, a blade body 13, and a tenon 14 connected in sequence. A groove 15 is formed at the connection between the crystal selection section 11 and the blade crown 12 along the contour of the blade crown 12. The distance between the bottom of the groove 15 and the inner cavity core is 0.5 mm. Two groups of core positioning holes 16 are set on the blade wax mold 10, and their diameters are 2 mm.

[0086] S2, assembling a plurality of blade wax molds 10 to form a Figure 4 Wax model set shown.

[0087] The length of the edge of the highest solidification point of the blade crown 12 of the blade wax model 10 is 30 mm, and the 15 mm length of the edge close to the center of the wax model module is extended and raised to form an extension section 17, and the extension section 17 is 15 mm long and 2 mm wide. The edge of the extension section 17 is further extended in the horizontal direction to form a feeding platform 18, and the width of the feeding platform 18 is 3 mm.

[0088] A rectangular-shaped feeding wax block 20 is pressed, and the size of the wax block is 15 mm×15 mm×3 mm. A feeding wax block 20 of the same size is vertically bonded on the feeding platform 18 .

[0089] A base 30 with a diameter of 300 mm is selected for wax model module assembly. The feeding wax block 20 is assembled toward the center of the wax model module, and the inner end point of the edge of the highest solidification point of the blade crown 12 close to the center of the module and the radial line of the center of the module form an angle of 45° with the edge, and the feeding wax block 20 is located close to the center of the wax model module.

[0090] A heat-insulating wax mold sleeve 40 with a diameter of 90 mm and a thickness of 5 mm is arranged at the center of the wax mold module. Its upper edge is 20 mm higher than the shrinkage-feeding wax block 20 , and its outer surface is kept at a distance of 25 mm from the shrinkage-feeding wax block 20 .

[0091] S3, using the wax mold assembly to prepare a casting shell.

[0092] S4, assembling the casting shell and the inner cavity core to form a casting module.

[0093] S5, pouring molten metal into the casting mold, and making the molten metal start to grow from the blade crown end through directional solidification, so as to prepare a hollow shrouded turbine blade with no loose defects in the blade crown. The pulling rate during directional solidification is 4 mm / min.

[0094] Comparative Example 1

[0095] The turbine working blades are cast by a traditional casting method, and the method of selective crystal growth starting from the tenon section is adopted. No groove 15 is set in the crystal selection section, and no insulating wax mold sleeve 40 is set. The edge of the highest point of the blade crown solidification is perpendicular to the radial direction of the wax mold module, and a cylindrical shrinkage block is set next to the edge to compensate for the shrinkage of the blade crown.

[0096] The blade crowns of the turbine working blades prepared in Example 1 and Comparative Example 1 were observed. Figure 7 and Figure 8 As shown, there is no loose defect at the edge of the leaf crown of Example 1, while there are a large number of loose defects at the edge of the leaf crown of Comparative Example 1.

[0097] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for eliminating the loose defect of the turbine blade shroud position, characterized in that: include: Step S1, preparing a blade wax mold, wherein the blade wax mold includes a crystal selection section, a blade crown, a blade body, and a tenon that are integrally formed and connected in sequence, and a groove is formed at the connection between the crystal selection section and the blade crown along the contour of the blade crown; Step S2, assembling a plurality of the blade wax models to form a wax model module, in which the plurality of blade wax models are distributed in a circumferential direction around the center of the wax model module; Step S3, using the wax mold assembly to prepare a casting shell, so that a blocking protrusion is formed at a corresponding position between the inner surface of the casting shell and the groove of the blade wax mold; Step S4, assembling the casting shell and the inner cavity core to form a casting module, and forming a crystal selection growth channel between the casting shell barrier protrusion and the inner cavity core; Step S5, pouring molten metal into the casting mold, and causing the molten metal to selectively grow from the blade crown end through directional solidification, so as to prepare a hollow shrouded turbine blade with no loose defects in the blade crown.

2. The method according to claim 1, characterized in that In step S1, when preparing the blade wax mold, the distance between the bottom of the groove and the inner cavity core is controlled to be 0.5-1 mm, so that the width of the selective crystal growth channel is 0.5-1 mm.

3. The method according to claim 1, characterized in that The blade crown is arranged obliquely relative to the blade body; In step S2, when assembling the wax mold module, the edge of the highest solidification point of the leaf crown is oriented toward the center of the wax mold module and forms an angle with the radial direction of the wax mold module, and a shrinkage wax block is arranged next to the edge of the highest solidification point of the leaf crown.

4. The method according to claim 3, characterized in that When assembling the wax mold assembly, the edge of the highest solidification point of the blade crown is oriented toward the center of the wax mold assembly, and the angle between the radial line between the edge and the center of the wax mold assembly and the edge itself is 45°.

5. The method according to claim 3, characterized in that: In step S1, when preparing the blade wax model, a portion of the edge of the highest solidification point of the blade crown close to the center of the wax model module is further extended outward along the inclined direction of the blade crown to increase height, and the heightened edge is further extended outward in the horizontal direction to form a feeding platform of a predetermined width; In step S2, when assembling the wax model module, the feeding wax block is placed on the feeding platform.

6. The method according to claim 5, characterized in that In step S2, when assembling the wax model module, the feeding wax block is bonded to the feeding platform, the feeding wax block is a cuboid, the feeding wax block is vertically arranged to the feeding platform, and the bonding surface of the feeding wax block matches the size of the feeding platform.

7. The method according to claim 1, characterized in that In step S2, when assembling the wax mold module set, a heat-insulating wax mold sleeve is arranged in the space formed by the plurality of blade wax molds, so that the heat-insulating wax mold sleeve is located at the center of the wax mold module set and is spaced apart from the blade wax molds.

8. The method according to claim 7, characterized in that The distance between the outer surface of the insulating wax mold sleeve and the shrinkage feeding wax block of the blade crown is maintained at 25-30 mm, and the upper surface of the insulating wax mold sleeve is higher than the shrinkage feeding wax block by no less than 20 mm.

9. The method according to any one of claims 1 to 8, characterized in that: In step S5, the casting mold is placed in a heating device, and when the casting mold reaches a predetermined temperature and is kept warm, the molten metal is poured into the casting mold; The casting mold is pulled out and separated from the heating device, so that the molten metal starts to directionally solidify from the blade crown end, and the pulling rate is controlled to be 3-5 mm / min.

10. A wax mold assembly for eliminating loose defects of inclined blade crowns, characterized in that: include: Pouring gate, upper runner, multiple blade wax molds, insulation wax mold sleeve, base; The pouring port is connected to the upper pouring channel, the upper pouring channel is spaced apart from the base, and the plurality of blade wax molds are connected between the upper pouring channel and the base; The thermal insulation wax mold sleeve is connected to the base, and the pouring port, the upper runner, the thermal insulation wax mold sleeve and the base are concentrically arranged; A plurality of the blade wax models are evenly arranged around the thermal insulation wax model sleeve; Among them, the blade wax mold includes a crystal selection section, a blade crown, a blade body and a tenon connected in sequence, the crystal selection section is connected to the base, and the tenon is connected to the upper runner; a groove is provided at the connection between the crystal selection section and the blade crown along the contour shape of the blade crown.

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