CN107008857B - Ceramic mould shell capable of eliminating casting hot cracking defect of variable cross-section part and forming method thereof - Google Patents

Ceramic mould shell capable of eliminating casting hot cracking defect of variable cross-section part and forming method thereof Download PDF

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Publication number
CN107008857B
CN107008857B CN201710250276.9A CN201710250276A CN107008857B CN 107008857 B CN107008857 B CN 107008857B CN 201710250276 A CN201710250276 A CN 201710250276A CN 107008857 B CN107008857 B CN 107008857B
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ceramic
shell
casting
wax
variable
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CN107008857A (en
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王海伟
张琼元
杨啊涛
张建平
巩秀芳
杨功显
王海洋
张松泉
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DEC Dongfang Turbine Co Ltd
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DEC Dongfang Turbine Co Ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22CFOUNDRY MOULDING
    • B22C9/00Moulds or cores; Moulding processes
    • B22C9/02Sand moulds or like moulds for shaped castings
    • B22C9/04Use of lost patterns
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22CFOUNDRY MOULDING
    • B22C9/00Moulds or cores; Moulding processes
    • B22C9/22Moulds for peculiarly-shaped castings

Abstract

The invention discloses a ceramic mould shell capable of eliminating casting heat cracking defects of variable cross-section parts and a forming method thereof. The ceramic formwork is provided with a casting cavity matched with a design structure of a variable cross-section part, a corresponding hot spot area is arranged in the casting cavity according to the solidification characteristic of molten steel in the casting cavity in the casting process, an inner concave groove is arranged on the outer surface of the ceramic formwork corresponding to the hot spot area, and the width and the length of the inner concave groove correspond to the hot spot area in the casting cavity. The ceramic mould shell ensures the structural strength and simultaneously realizes effective and reliable differential control on the thickness of the ceramic mould shell, namely the ceramic mould shell well eliminates the shrinkage stress at the position of a thermal joint and avoids the generation of the defect of thermal cracking.

Description

Ceramic mould shell capable of eliminating casting hot cracking defect of variable cross-section part and forming method thereof
Technical Field
The invention relates to a fired mold technology of a precision casting process, in particular to a ceramic mold shell capable of eliminating casting heat cracking defects of variable-section parts in the precision casting process and a forming method of the ceramic mold shell.
Background
The non-allowance investment precision casting process is the most common technology for forming high-temperature alloy parts (such as blades of aero-engines or blades of industrial gas turbines and the like), and the formed high-temperature alloy parts have good high-temperature mechanical properties and are widely applied to industrial equipment (such as aero-engines or industrial gas turbines and the like) with harsh service conditions.
However, the allowance-free investment precision casting process often causes some casting defects on a casting blank during the forming process of a high-temperature alloy part, which is most prominent in precision casting particularly for parts with variable sections of designed structures.
In the non-allowance investment precision casting process of the variable-section part, the most common casting defect is a hot cracking defect. The main causes of this casting defect are: the alloy in the ceramic mould shell can not be fully condensed when being solidified and can produce stress due to solidification shrinkage. Specifically, a casting cavity of the ceramic mould shell matched with the design structure of the variable cross-section part is provided with a corresponding heat section area, and the heat section area in the casting cavity corresponds to the cross-section mutation part of the variable cross-section part, so that a solidified casting in the ceramic mould shell is blocked by the ceramic mould shell to generate thermal stress when being solidified and shrunk, and the solidified casting is easy to compensate for insufficient shrinkage, so that a hot cracking defect is easily generated at the heat section area; for example, in the case of a superalloy blade, the most common occurrence of hot cracking defects in casting is the connecting section between the tip shroud (or platform) and the blade body or between the dovetail and the blade body.
The hot cracking defect of the variable cross-section part generated in the precision casting process not only seriously affects the forming quality of the variable cross-section part, but also reduces the qualification rate of the variable cross-section part blank and even brings potential safety hazard. Therefore, the hot cracking defect is a technical problem which needs to be solved in the precision casting process of the variable cross-section part for a long time.
In view of the above, the industry is actively searching for how to effectively and reliably eliminate the hot cracking defect of the variable cross-section part in the precision casting process. At present, regarding the elimination of the hot cracking defect of the variable cross-section part in the precision casting process in the industry, the general research focuses on the technical aspects of the selection of alloy components of precision casting, the pouring process of alloy melt and the like, and the research on the influence of the ceramic formwork structure and the forming process on the hot cracking defect is not considered.
Disclosure of Invention
The technical purpose of the invention is as follows: aiming at the particularity of the variable cross-section part and the current situation and the defects of the prior art, the ceramic formwork and the forming method of the ceramic formwork are provided, wherein the structural strength is ensured, and meanwhile, the thickness of the precision casting ceramic formwork of the variable cross-section part can be controlled in a differentiated mode, so that the casting heat cracking defect of the variable cross-section part can be reliably and effectively eliminated.
The technical scheme adopted by the invention for realizing the technical purpose is that the ceramic formwork can eliminate the casting heat crack defect of the variable cross-section part, the ceramic formwork is provided with a casting cavity matched with the design structure of the variable cross-section part, a corresponding hot spot area is arranged in the casting cavity according to the solidification characteristic of molten steel in the casting cavity in the casting process, an inner concave groove is arranged at the position of the outer surface of the ceramic formwork, which corresponds to the hot spot area, and the width and the length of the inner concave groove correspond to the hot spot area in the casting cavity.
As a preferred scheme, the width of an inner concave groove on the outer surface of the ceramic formwork is 1-10 mm, the depth of the inner concave groove is 1-10 mm, and the thickness of the wall of the ceramic formwork at the position of the inner concave groove is 4-20 mm. Furthermore, the ceramic mould shell is used for casting and forming the high-temperature alloy blade.
A method for forming a ceramic mould shell capable of eliminating casting heat cracking defects of variable cross-section parts comprises the following steps:
step 1, manufacturing a wax mould and dipping mortar and pouring sand to prepare a primary ceramic shell product according to a variable cross-section part with a designed structure;
step 2, fixing wax strips corresponding to the areas of the hot joint regions on the outer surfaces of the primary ceramic shell products, wherein the hot joint regions correspond to the areas of the wax strips;
step 3, continuously dipping the outer surface of the primary ceramic shell product with the wax strips into slurry and spraying sand to perform subsequent shell making until the required thickness is reached, and ensuring that the outer surface of the wax strips is exposed and visible on the outer surface of the ceramic shell;
and 4, dewaxing and roasting the ceramic mould shell obtained in the step 3 to obtain a ceramic mould shell finished product with an inner concave groove on the outer surface.
Preferably, the thickness of the wall of the primary ceramic shell in the step 1 is 4-20 mm, and the width of the wax strip in the step 2 is 1-10 mm and the thickness of the wax strip is 1-10 mm.
Furthermore, the ceramic mould shell is used for casting and forming the high-temperature alloy blade.
Preferably, the ceramic shell primary product in the step 2 is fixed by a wax strip after floating sand on the outer surface is removed. Furthermore, floating sand on the outer surface of the primary ceramic shell product is removed in an air drying mode, and the air drying time is 0.5-2 hours.
The beneficial technical effects of the invention are as follows:
1. the ceramic mould shell of the invention ensures the structural strength and simultaneously forms an inner concave groove structure on the outer surface of the ceramic mould shell corresponding to the thermal-junction area, thereby realizing effective and reliable differential control of the thickness of the ceramic mould shell for precision casting of variable-section parts, namely, the invention carries out effective and reliable balancing treatment on the structural strength of the ceramic mould shell and the elimination of contraction thermal stress which are mutually contradictory, not only improves the structural strength of the ceramic mould shell by increasing the layer number of the ceramic mould shell and avoids the technical problems of steel leakage, bulging deformation and the like possibly occurring in the precision casting process of the ceramic mould shell, but also effectively and reliably reduces the resistance suffered by the variable-section parts during the solidification contraction in the precision casting process and effectively and reliably eliminates the stress and heat by designing the inner concave groove on the outer surface of the ceramic mould shell corresponding to the thermal-junction area, the technical purpose of eliminating the casting hot cracking defect of the variable cross-section part is achieved;
2. the inner concave groove structure on the ceramic mould shell is designed aiming at the precision casting of a variable cross-section part, namely a high-temperature alloy blade, and has the characteristics of strong pertinence, reliable forming, good stability, high qualification rate and the like on the casting forming of the high-temperature alloy blade in the precision casting forming process of the high-temperature alloy blade;
3. the forming method of the invention is designed aiming at the ceramic mould shell structure of the invention, which can easily, conveniently, efficiently, accurately, reliably, stably and economically form the ceramic mould shell for casting the variable cross-section part with the concave groove on the outer surface corresponding to the thermal joint area, and effectively and reliably control the thickness of the ceramic mould shell in a differentiation way, thereby realizing effective and reliable balance treatment by improving the structural strength of the ceramic mould shell and eliminating the shrinkage thermal stress which are mutually contradictory, improving the structural strength of the ceramic mould shell by increasing the layer number of the ceramic mould shell, avoiding the technical problems of steel leakage, bulging deformation and the like which are possibly generated in the precision casting process of the ceramic mould shell, and effectively and reliably reducing the resistance of the variable cross-section part during the solidification shrinkage in the precision casting process by designing the concave groove structure on the outer surface of the ceramic mould shell corresponding to the thermal joint area, effectively and reliably eliminating thermal stress, and finally achieving the technical purpose of eliminating the casting hot crack defect of the variable cross-section part;
4. the wax strip structural design is designed for forming the inner concave groove of the ceramic mould shell for precision casting of the variable cross-section part, namely the high-temperature alloy blade, and the formed inner concave groove can effectively meet the technical requirement of eliminating the casting heat cracking defect of the high-temperature alloy blade in the precision casting forming process.
Drawings
FIG. 1 is a schematic view of a ceramic form of the present invention.
FIG. 2 is a schematic view showing a state of the molding method of the present invention (i.e., a state in which a wax strip is fixed to a ceramic shell preform).
Fig. 3 is a schematic view showing another state of the molding method of the present invention (i.e., the state of the finally molded ceramic shell).
The reference numbers in the figures mean: 1-ceramic mould shell; 2-casting a cavity; 3-an inner concave groove; 4-wax strip.
Detailed Description
The invention relates to a ceramic mould shell for a precision casting process, in particular to a ceramic mould shell capable of eliminating casting heat cracking defects of variable-section parts and a forming method of the ceramic mould shell. The technical content of the present invention will be described in detail below with reference to a plurality of examples. The embodiment 1 is described in detail and specifically with reference to fig. 1 to 3, and the main structure of other embodiments can refer to the drawings of the embodiment 1, although not separately depicted.
Example 1
Referring to fig. 1, the invention is a ceramic mould shell for precision casting of a variable cross-section part, namely a heavy duty gas turbine guide vane, wherein the ceramic mould shell 1 is provided with a casting cavity 2 matched with the design structure of the turbine guide vane.
The casting cavity 2 has an inner edge plate portion, a blade body portion and an outer edge plate portion according to the turbine guide blade, and a section abrupt structure is formed at a connection transition portion of the inner edge plate portion and the blade body portion and a connection transition portion of the outer edge plate portion and the blade body portion, that is, the section areas of the inner edge plate portion and the outer edge plate portion are larger than the section area of the blade body portion. When molten steel is cast in the casting cavity 2 with the structure to carry out precision casting, the section abrupt change part generates a thermal throttling effect, namely, the solidification process of the section abrupt change part is slower than that of the periphery, so that the thermal cracking defects including looseness exist. That is, according to the solidification characteristics of molten steel in the casting cavity 2 during casting, the casting cavity 2 has two corresponding hot spot regions, one is located at the connecting transition between the inner edge plate portion and the blade body portion, and the other is located at the connecting transition between the outer edge plate portion and the blade body portion.
In view of this, two inner concave grooves 3 are arranged at the outer surface of the ceramic mould shell 1 corresponding to the thermal joint area, that is, one inner concave groove 3 is arranged at the outer surface of the connecting transition part of the inner edge plate part and the blade body part, and the other inner concave groove 3 is arranged at the outer surface of the connecting transition part of the outer edge plate part and the blade body part. The width and the length of each inner concave groove 3 correspond to the corresponding hot spot area in the casting cavity 2, the width of each inner concave groove 3 is about 3mm, the depth is about 5mm, and the length is the circumferential length of the corresponding part of the ceramic mould shell 1. The thickness of the wall of the ceramic mould shell 1 at each concave groove 3 is about 10 mm.
Referring to fig. 2 and 3, the method for forming a ceramic form of the present invention comprises the steps of:
step 1, manufacturing corresponding wax molds and other auxiliary wax molds (including a pouring channel wax mold, a crystal-opening wax mold and the like) according to the turbine guide blade with the designed structure; forming the wax pattern into a wax tree;
manufacturing a wax strip 4 according to a hot spot area of a turbine guide blade with a designed structure in the precision casting forming process, wherein the width of the wax strip 4 is about 3mm, the thickness of the wax strip 4 is about 5mm, and the length of the wax strip is matched with the perimeter of a corresponding part of a primary ceramic shell product; the wax strip 4 is used for standby;
dipping slurry and sand-spraying on a wax tree, preparing a ceramic shell, and carrying out multi-layer slurry dipping and sand-spraying treatment to obtain a primary ceramic shell product on a wax mould of the turbine guide blade, wherein the thickness of the wall of the primary ceramic shell product is about 10 mm;
step 2, removing floating sand on the outer surface of the primary ceramic shell product in an air drying mode, wherein the air drying time is about 1.5 hours, so that the floating sand on the outer surface of the primary ceramic shell product is basically removed;
fixing the wax strips 4 to be used at the corresponding positions of the outer surface of the primary ceramic shell product at the corresponding hot spot areas of the outer surface of the primary ceramic shell product after the floating sand is removed, so that the wax strips 4 correspond to the hot spot areas on the ceramic mould shell and the areas of the wax strips 4;
step 3, continuously dipping slurry and spraying sand on the outer surface of the primary ceramic shell product with the wax strips 4 to prepare a subsequent ceramic shell, and then carrying out multilayer slurry dipping and sand spraying treatment to obtain a ceramic shell with the required thickness on a wax mould of the turbine guide blade, wherein the outer surface of the ceramic shell is basically flush with the outer surface of the wax strips 4, but the outer surface of the wax strips 4 is required to be exposed and visible on the outer surface of the ceramic shell;
and 4, dewaxing and roasting the ceramic mould shell obtained in the step 3 to obtain a ceramic mould shell finished product with the inner concave groove 3 on the outer surface.
Example 2
The invention relates to a ceramic mould shell for precision casting of variable cross-section parts and turbine blades, which is provided with a casting cavity matched with the design structure of the turbine blades.
The casting cavity is provided with a blade crown part, a blade body part and a tenon root part according to the turbine blade, and the connection transition positions of the blade crown part, the tenon root part and the blade body part respectively form a section abrupt change structure, namely the section areas of the blade crown part and the tenon root part are larger than the section area of the blade body part. When molten steel is cast in the casting cavity with the structure for precision casting, the section abrupt change part generates a thermal-section effect, namely, the solidification process of the section abrupt change part is slower than that of the periphery, so that the defect of thermal cracking including looseness exists. That is, according to the solidification characteristics of molten steel in the casting cavity during casting, the casting cavity has two corresponding hot spot regions, one at the junction transition between the blade crown portion and the blade body portion, and the other at the junction transition between the tenon root portion and the blade body portion.
In view of this, two inner concave grooves are arranged at the outer surface of the ceramic mould shell corresponding to the hot spot area, namely, one inner concave groove is arranged at the outer surface of the connecting transition part of the blade crown part and the blade body part, and the other inner concave groove is arranged at the outer surface of the connecting transition part of the tenon root part and the blade body part. The width and the length of each inner concave groove correspond to the corresponding hot spot area in the casting cavity, the width of each inner concave groove is about 6mm, the depth of each inner concave groove is about 8mm, and the length of each inner concave groove is the circumferential length of the corresponding part of the ceramic mould shell. The thickness of the wall of the ceramic mould shell at each concave groove is about 15 mm.
The invention relates to a method for forming a ceramic mould shell, which comprises the following steps:
step 1, manufacturing corresponding wax molds and other auxiliary wax molds (including a pouring channel wax mold, a crystal opening wax mold and the like) according to the turbine blade with the designed structure; forming the wax pattern into a wax tree;
manufacturing a wax strip according to a hot spot area of the turbine blade with a designed structure in the precision casting forming process, wherein the width of the wax strip is about 6mm, the thickness of the wax strip is about 8mm, and the length of the wax strip is matched with the perimeter of the corresponding part of the primary ceramic shell; the wax strips are used for later use;
dipping slurry and sand-spraying on a wax tree, preparing a ceramic shell, and carrying out multi-layer dipping and sand-spraying treatment to obtain a primary ceramic shell product on a wax mold of the turbine blade, wherein the thickness of the wall of the primary ceramic shell product is about 15 mm;
step 2, removing floating sand on the outer surface of the primary ceramic shell product in an air drying mode, wherein the air drying time is about 2 hours, so that the floating sand on the outer surface of the primary ceramic shell product is basically removed;
fixing the wax strips to be used at the corresponding positions of the outer surface of the primary ceramic shell product at the corresponding hot spot areas of the outer surface of the primary ceramic shell product after the floating sand is removed, so that the wax strips correspond to the hot spot areas on the ceramic shell and the areas of the wax strips are also corresponding to the hot spot areas;
step 3, continuously dipping slurry and spraying sand on the outer surface of the primary ceramic shell product with the wax strips, preparing a subsequent ceramic shell, and performing multi-layer slurry dipping and sand spraying treatment to obtain a ceramic shell with required thickness on a wax mould of the turbine blade, wherein the outer surface of the ceramic shell is basically flush with the outer surface of the wax strips, but the outer surface of the wax strips is required to be exposed and visible on the outer surface of the ceramic shell;
and 4, dewaxing and roasting the ceramic mould shell obtained in the step 3 to obtain a ceramic mould shell finished product with an inner concave groove on the outer surface.
Example 3
The invention relates to a ceramic mould shell for precision casting of variable cross-section parts, namely small T-shaped high-temperature alloy parts, which is provided with a casting cavity matched with the design structure of the T-shaped high-temperature alloy parts.
The casting cavity is provided with a crown part and a body part according to the T-shaped high-temperature alloy part, and a section abrupt change structure is formed at the connecting transition position of the crown part and the body part, namely the section area of the crown part is larger than that of the body part. When molten steel is cast in the casting cavity with the structure for precision casting, the section abrupt change part generates a thermal-section effect, namely, the solidification process of the section abrupt change part is slower than that of the periphery, so that the defect of thermal cracking including looseness exists. That is, depending on the solidification behavior of the molten steel in the casting cavity during casting, the casting cavity has a hot spot region at the transition between the crown and the body.
In view of this, an inner concave groove is arranged at the position of the outer surface of the ceramic mould shell corresponding to the hot spot area, namely, the inner concave groove is arranged at the outer surface of the connecting transition position of the crown part and the body part. The width and the length of the inner concave groove correspond to the corresponding hot spot area in the casting cavity, the width of the inner concave groove is about 1mm, the depth of the inner concave groove is about 2mm, and the length of the inner concave groove is the circumferential length of the corresponding part of the ceramic mould shell. The thickness of the wall of the ceramic mould shell at the position of the inner concave groove is about 5 mm.
The invention relates to a method for forming a ceramic mould shell, which comprises the following steps:
step 1, manufacturing corresponding wax molds and other auxiliary wax molds (including a pouring channel wax mold, a crystal-opening wax mold and the like) according to the T-shaped high-temperature alloy part with the designed structure; forming the wax pattern into a wax tree;
manufacturing a wax strip according to a hot spot area of a T-shaped high-temperature alloy part with a designed structure in the precision casting forming process, wherein the width of the wax strip is about 1mm, the thickness of the wax strip is about 2mm, and the length of the wax strip is matched with the perimeter of a corresponding part of a primary ceramic shell product; the wax strips are used for later use;
dipping slurry and sand-spraying on a wax tree, preparing a ceramic shell, and carrying out multi-layer slurry dipping and sand-spraying treatment to obtain a primary ceramic shell product on a wax mould of the T-shaped high-temperature alloy part, wherein the thickness of the wall of the primary ceramic shell product is about 5 mm;
step 2, removing floating sand on the outer surface of the primary ceramic shell product in an air drying mode, wherein the air drying time is about 0.5 hour, so that the floating sand on the outer surface of the primary ceramic shell product is basically removed;
fixing the wax strips to be used at the corresponding positions of the outer surface of the primary ceramic shell product at the corresponding hot spot areas of the outer surface of the primary ceramic shell product after the floating sand is removed, so that the wax strips correspond to the hot spot areas on the ceramic shell and the areas of the wax strips are also corresponding to the hot spot areas;
step 3, continuously dipping slurry and spraying sand on the outer surface of the primary ceramic shell product with the wax strips, preparing a subsequent ceramic shell, and performing multi-layer slurry dipping and sand spraying treatment to obtain a ceramic shell with a required thickness on a wax mould of the T-shaped high-temperature alloy part, wherein the outer surface of the ceramic shell is basically flush with the outer surface of the wax strips, but the outer surface of the wax strips is required to be exposed and visible on the outer surface of the ceramic shell;
and 4, dewaxing and roasting the ceramic mould shell obtained in the step 3 to obtain a ceramic mould shell finished product with an inner concave groove on the outer surface.
Example 4
The invention relates to a ceramic mould shell for precision casting of variable cross-section parts and large-scale T-shaped high-temperature alloy parts, which is provided with a casting cavity matched with the design structure of the T-shaped high-temperature alloy parts.
The casting cavity is provided with a crown part and a body part according to the T-shaped high-temperature alloy part, and a section abrupt change structure is formed at the connecting transition position of the crown part and the body part, namely the section area of the crown part is larger than that of the body part. When molten steel is cast in the casting cavity with the structure for precision casting, the section abrupt change part generates a thermal-section effect, namely, the solidification process of the section abrupt change part is slower than that of the periphery, so that the defect of thermal cracking including looseness exists. That is, depending on the solidification behavior of the molten steel in the casting cavity during casting, the casting cavity has a hot spot region at the transition between the crown and the body.
In view of this, an inner concave groove is arranged at the position of the outer surface of the ceramic mould shell corresponding to the hot spot area, namely, the inner concave groove is arranged at the outer surface of the connecting transition position of the crown part and the body part. The width and the length of the inner concave groove correspond to the corresponding hot spot area in the casting cavity, the width of the inner concave groove is about 10mm, the depth of the inner concave groove is about 10mm, and the length of the inner concave groove is the circumferential length of the corresponding part of the ceramic mould shell. The thickness of the wall of the ceramic mould shell at the position of the inner concave groove is about 20 mm.
The invention relates to a method for forming a ceramic mould shell, which comprises the following steps:
step 1, manufacturing corresponding wax molds and other auxiliary wax molds (including a pouring channel wax mold, a crystal-opening wax mold and the like) according to the T-shaped high-temperature alloy part with the designed structure; forming the wax pattern into a wax tree;
manufacturing a wax strip according to a hot spot area of a T-shaped high-temperature alloy part with a designed structure in the precision casting forming process, wherein the width of the wax strip is about 10mm, the thickness of the wax strip is about 10mm, and the length of the wax strip is matched with the perimeter of a corresponding part of a primary ceramic shell product; the wax strips are used for later use;
dipping slurry and sand-spraying on a wax tree, preparing a ceramic shell, and carrying out multi-layer slurry dipping and sand-spraying treatment to obtain a primary ceramic shell product on a wax mould of the T-shaped high-temperature alloy part, wherein the thickness of the wall of the primary ceramic shell product is about 20 mm;
step 2, removing floating sand on the outer surface of the primary ceramic shell product in an air drying mode, wherein the air drying time is about 1 hour, so that the floating sand on the outer surface of the primary ceramic shell product is basically removed;
fixing the wax strips to be used at the corresponding positions of the outer surface of the primary ceramic shell product at the corresponding hot spot areas of the outer surface of the primary ceramic shell product after the floating sand is removed, so that the wax strips correspond to the hot spot areas on the ceramic shell and the areas of the wax strips are also corresponding to the hot spot areas;
step 3, continuously dipping slurry and spraying sand on the outer surface of the primary ceramic shell product with the wax strips, preparing a subsequent ceramic shell, and performing multi-layer slurry dipping and sand spraying treatment to obtain a ceramic shell with a required thickness on a wax mould of the T-shaped high-temperature alloy part, wherein the outer surface of the ceramic shell is basically flush with the outer surface of the wax strips, but the outer surface of the wax strips is required to be exposed and visible on the outer surface of the ceramic shell;
and 4, dewaxing and roasting the ceramic mould shell obtained in the step 3 to obtain a ceramic mould shell finished product with an inner concave groove on the outer surface.
Example 5
The other contents of this embodiment are the same as those of embodiment 1 or 2, except that: the variable cross-section part is a hollow blade; a ceramic core is arranged in a casting cavity of the ceramic mould shell; the wax mould is also provided with a corresponding ceramic core during the manufacture.
The above examples are intended to illustrate the invention, but not to limit it; although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: the present invention may be modified from the embodiments described above or substituted for some of the technical features, and such modifications or substitutions do not depart from the spirit and scope of the present invention.

Claims (5)

1. A ceramic shuttering capable of eliminating casting heat crack defects of variable cross-section parts, wherein the variable cross-section parts are high-temperature alloy blades, the high-temperature alloy blades are provided with cross-section mutation parts with cross-section areas larger than the cross-section areas of blade bodies, the ceramic shuttering (1) is provided with a casting cavity (2) matched with the design structure of the high-temperature alloy blades, and hot spot areas corresponding to the connection transition positions of the blade bodies and the cross-section mutation parts are arranged in the casting cavity (2) according to the solidification characteristics of molten steel in the casting cavity (2) in the casting process, and the ceramic shuttering is characterized in that: the ceramic formwork (1) is prepared by slurry dipping and sand spraying, an inner concave groove (3) is formed in the position, corresponding to a heat joint area, of the outer surface of the ceramic formwork (1), the width of the inner concave groove (3) in the outer surface of the ceramic formwork (1) is 1-10 mm, the depth of the inner concave groove (3) is 1-10 mm, the wall thickness of the ceramic formwork (1) in the position of the inner concave groove (3) is 4-20 mm, and the width and the length of the inner concave groove (3) correspond to the heat joint area in the casting cavity (2).
2. A method of forming a ceramic form in accordance with claim 1 to eliminate casting hot defects in a variable cross-section part, comprising the steps of:
step 1, manufacturing a wax mould and dipping mortar and pouring sand to prepare a primary ceramic shell product according to a variable cross-section part with a designed structure;
step 2, fixing wax strips corresponding to the areas of the hot joint regions on the outer surfaces of the primary ceramic shell products, wherein the hot joint regions correspond to the areas of the wax strips;
step 3, continuously dipping the outer surface of the primary ceramic shell product with the wax strips into slurry and spraying sand to perform subsequent shell making until the required thickness is reached, and ensuring that the outer surface of the wax strips is exposed and visible on the outer surface of the ceramic shell;
and 4, dewaxing and roasting the ceramic mould shell obtained in the step 3 to obtain a ceramic mould shell finished product with an inner concave groove on the outer surface.
3. The method of claim 2, further comprising the step of forming a ceramic form with the capability of eliminating casting hot cracks in the variable cross-section part: the thickness of the wall of the primary ceramic shell in the step 1 is 4-20 mm, and the width of the wax strip in the step 2 is 1-10 mm and the thickness of the wax strip is 1-10 mm.
4. The method of claim 2, further comprising the step of forming a ceramic form with the capability of eliminating casting hot cracks in the variable cross-section part: and (3) removing floating sand on the outer surface of the primary ceramic shell in the step (2) and then fixing the wax strips.
5. The method of claim 4, wherein the step of forming the ceramic form includes the steps of: and removing floating sand on the outer surface of the primary ceramic shell in an air drying mode, wherein the air drying time is 0.5-2 hours.
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