Method and device for casting stainless steel impeller

Abstract

The stainless steel impeller casting method comprises the following steps that S1, a core mold is assembled, specifically, a conical base and at least three spiral sand cores are provided, all the spiral sand cores are sequentially hoisted and installed to the conical base, the inner side walls of all the spiral sand cores and the outer conical surface of the conical base are attached and positioned, and the core mold is assembled; then all the spiral sand cores are sequentially assembled and fixed in the circumferential direction of the conical base, so that a forming gap matched with the blade molded line of the impeller is formed between every two adjacent spiral sand cores, and a combined core mold is formed; s2, preparing an outer mold; s3, modeling and pouring are conducted; and S4, box opening and shakeout are conducted. According to the technical scheme, the conical base is arranged as a unified installation reference, and the inner side walls of all the spiral sand cores are attached to the precise outer conical surface of the conical base, so that the consistency of the relative positions of all the sand cores is ensured, and the precise size and the correct molded line of a molding gap formed between the adjacent spiral sand cores are further ensured.

Description

Technical Field

[0002] This invention relates to the field of impeller casting technology, and in particular to a method and apparatus for casting stainless steel impellers. Background Technology

[0004] As a core component of fluid machinery such as pumps and fans, the quality of stainless steel impellers directly affects the overall efficiency and operational stability of the machine. Closed impellers, due to their enclosed flow channels, have high hydraulic efficiency, but are difficult to cast. In traditional casting of closed impellers, the complex internal blade cavities usually require the use of integral cores or modular composite cores.

[0005] In existing technologies, the lack of precise positioning references when using modular core assembly makes the assembly process cumbersome, and the relative positions between the core blocks are not easy to guarantee, which in turn affects the final impeller flow channel dimensional accuracy and easily leads to casting deviations. Summary of the Invention

[0007] Therefore, a method and apparatus for casting stainless steel impellers are needed to solve the technical problem that the lack of precise positioning reference when using modular core assembly leads to a cumbersome assembly process, makes it difficult to guarantee the relative position between the core blocks, and thus affects the final impeller flow channel dimensional accuracy and easily causes casting deviations.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a method for casting a stainless steel impeller, comprising the following steps:

[0009] S1. Core Mold Assembly: Provide a conical base and at least three spiral sand cores. Hoist and install each spiral sand core onto the conical base in sequence, so that the inner sidewall of each spiral sand core fits and is positioned against the outer conical surface of the conical base. Then, assemble and fix all the spiral sand cores in sequence along the circumference of the conical base, so that a forming gap that matches the blade profile of the impeller is formed between two adjacent spiral sand cores, thereby forming a combined core mold composed of all the spiral sand cores.

[0010] S2. Outer mold preparation: The outer mold is made according to the external dimensions of the impeller product;

[0011] S3. Molding and Casting: The outer mold is placed in the sand box to form the outer mold sand pattern. Then, the combined core mold is removed from the conical base and placed into the outer mold sand pattern. After the box is closed, the casting mold is formed. Next, molten stainless steel is injected into the casting mold through the gating system until the casting is completed.

[0012] S4. Unpacking and Sand Removal: After the casting has cooled and solidified, open the sand box, remove the sand, and take out the formed impeller casting.

[0013] Unlike existing technologies, the above-mentioned solution introduces a conical base with an outer conical surface as a unified installation reference for all helical sand cores. The inner walls of all helical sand cores are fitted with the precise outer conical surface of this conical base, thereby obtaining a unified and accurate radial and axial positioning reference. This method simplifies the complex positioning problem of multiple independent helical sand cores in three-dimensional space into a problem of fitting and circumferentially arranging along a defined conical surface, ensuring the consistency of the relative positions of all helical sand cores, and thus ensuring the precise dimensions and correct profile of the molding gaps formed between adjacent helical sand cores. After assembly and fixing, only the lower core of the combined core mold is removed as a whole, and the conical base can be reused, balancing accuracy and efficiency.

[0014] In one embodiment of the present invention, in step S1, one side of the conical base has a lower height, forming an entrance area for the spiral sand core to enter; during installation, each spiral sand core is hoisted to the entrance area in sequence, enters through the area, and then moves to the designated position along the outer conical surface of the conical base.

[0015] Thus, the conical base, with its lower structural design on one side, naturally creates a low entrance without compromising the integrity of the conical surface. This provides an extremely convenient radial channel for the installation of the spiral sand core, allowing it to be easily pushed into the circumference of the conical base, significantly reducing the difficulty of hoisting and positioning and the risk of interference.

[0016] In one embodiment of the present invention, the entrance area is located at the circumferential starting position of the conical base.

[0017] By aligning the lower-side inlet area with the circumferential starting point, the first installed spiral sand core can directly reach its precise starting position upon entry. This ingenious integration of the inlet and positioning reference functions simplifies the structure and ensures a unique and accurate angular reference for assembly.

[0018] In one embodiment of the present invention, the step of moving to the designated position is completed by manual pushing until the inner sidewall of each spiral sand core is completely fitted and positioned with the outer conical surface of the conical base.

[0019] In this way, by utilizing the self-guiding effect of the conical base and conical surface, precise positioning can be achieved by manually pushing the spiral sand core to the designated position.

[0020] In one embodiment of the present invention, in step S1, all the spiral sand cores assembled on the conical base are fixed from the top.

[0021] In this way, by fixing all the spiral sand cores assembled on the conical base at the top, the combined core mold is prevented from shifting due to loosening during subsequent transfer or handling, thus ensuring the integrity and rigidity of the combined core mold structure before and after detaching from the conical base.

[0022] As one embodiment of the present invention, the fixing step specifically includes: first, local fixing at the side joint of two adjacent spiral sand cores; then, fixing all spiral sand cores assembled on the conical base as a whole from the top.

[0023] Thus, a step-by-step fixing strategy of "partial connection first, then overall locking" is adopted. Partial side fixing (such as bonding, snap-fitting, or bolting) first constrains adjacent spiral sand cores, initially forming a stable network structure; the subsequent overall top fixing provides the final strong clamping force. This method greatly enhances the overall deformation resistance of the combined core mold.

[0024] As one embodiment of the present invention, a guide structure is provided on the side of the spiral sand core. When the spiral sand core moves along the outer conical surface of the conical base, the guide structure is used to cooperate with the corresponding structure on the adjacent spiral sand core or the conical base to guide it to slide to the designated position.

[0025] Thus, the guiding structure (such as protrusions and grooves) provides a mechanical guide for the circumferential movement of the spiral sand core, making the sliding process smooth, precise and free of sway, significantly reducing the reliance on manual pushing skills, improving assembly efficiency, and ensuring the fit of the mating surfaces of adjacent spiral sand cores.

[0026] In one embodiment of the present invention, in step S1, positioning marks are provided on the mating surfaces of the spiral sand core and / or the conical base. During assembly, the spiral sand core is aligned with the positioning marks to determine whether it has reached the designated position.

[0027] In this way, positioning marks (such as scale lines and color marks) provide an intuitive visual alignment standard, enabling operators to quickly and objectively judge whether the assembly is in place, thus achieving standardization of the operation process and helping to ensure the consistency of product accuracy under different batches and different personnel operations.

[0028] In one embodiment of the present invention, the number of spiral sand cores is 5-7.

[0029] In this way, 5-7 spiral sand cores can form a uniformly distributed spiral channel inside the casting, effectively avoiding the channel sparseness and insufficient flow caused by too few cores, or the structural complexity and casting difficulties caused by too many cores, thereby ensuring the smooth flow of fluids (such as gas and liquid) and heat exchange efficiency.

[0030] To achieve the above objectives, in a second aspect, the present invention also provides a stainless steel impeller casting apparatus for implementing any of the methods provided by the inventors above, comprising:

[0031] A conical base, the outer surface of which is a conical surface used for positioning;

[0032] At least three spiral sand cores are arranged around a conical base, with their inner walls fitting the outer conical surface of the conical base. A molding gap that matches the blade profile of the impeller is formed between two adjacent spiral sand cores, together forming a combined core mold.

[0033] Fixing components are used to fix all the bonded spiral sand cores together to form a combined core mold.

[0034] Unlike existing technologies, the above-described technical solution provides a device specifically designed for the aforementioned method. This device uses a conical base as its core, with its conical surface providing a unified and precise positioning reference for all helical sand cores. Each helical sand core achieves self-positioning by fitting against the conical surface and is locked into a rigid whole by fixing components. This ingenious device transforms the manufacturing of the combined core mold used to form complex impeller flow channels into an assembly problem around a simple cone, greatly reducing the complexity and operational difficulty of specialized tooling, ensuring high precision and repeatability of the product. Simultaneously, the conical base, as a reusable tooling, reduces the unit cost.

[0035] The above description of the invention is merely an overview of the technical solution of this application. In order to enable those skilled in the art to better understand the technical solution of this application and to implement it based on the description and drawings, and to make the above-mentioned objectives and other objectives, features and advantages of this application easier to understand, the following description is provided in conjunction with the specific embodiments and drawings of this application. Attached Figure Description

[0037] The accompanying drawings are only used to illustrate the principles, implementation methods, applications, features, and effects of specific embodiments of this application and other related content, and should not be considered as limitations on this application.

[0038] In the accompanying drawings of the instruction manual:

[0039] Figure 1 This is a schematic diagram of the structure of a conical base according to an embodiment of this application;

[0040] Figure 2 This is a schematic diagram of a structure in one embodiment of the present application, showing two spiral sand cores assembled on a conical base;

[0041] Figure 3This is a schematic diagram of a structure in which three spiral sand cores are assembled on a conical base according to an embodiment of this application;

[0042] Figure 4 This is a schematic diagram of the structure of assembling a combined core mold on a conical base according to an embodiment of this application;

[0043] Figure 5 This is a structural schematic diagram from another perspective of assembling a combined core mold on a conical base according to an embodiment of this application;

[0044] Figure 6 This is a schematic diagram of the structure of the assembled core mold on the conical base according to an embodiment of this application, to be hoisted.

[0045] The reference numerals used in the above figures are explained as follows:

[0046] 1. Conical base; 11. Entrance area; 2. Spiral sand core; 21. Molding gap; 3. Combined core mold. Detailed Implementation

[0048] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0049] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0050] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0051] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.

[0052] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0053] Without further limitations, the use of terms such as “comprising,” “including,” “having,” or other similar open-ended expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0054] As understood in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0055] In the description of the embodiments of this application, the space-related expressions used, such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "vertical," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or drawings. They are only for the purpose of describing the specific embodiments of this application or for the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0056] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral arrangement; it can be a direct connection or an indirect connection through an intermediate medium; it can be a relationship of two components combined together, an interaction relationship between two components, or a connection within two structures. Those skilled in the art to which this application pertains can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0057] In existing technologies, the lack of precise positioning references when using modular core assembly makes the assembly process cumbersome, and the relative positions between the core blocks are not easy to guarantee, which in turn affects the final impeller flow channel dimensional accuracy and easily leads to casting deviations.

[0058] In view of this, embodiments of this application provide a method for casting a stainless steel impeller, comprising the following steps:

[0059] S1. Core mold assembly: Provide a conical base 1 and at least three spiral sand cores 2. Hoist and install each spiral sand core 2 onto the conical base 1 in sequence, so that the inner sidewall of each spiral sand core 2 fits and is positioned against the outer conical surface of the conical base 1. Then, assemble and fix all the spiral sand cores 2 in sequence along the circumference of the conical base 1, so that a forming gap 21 that matches the blade profile of the impeller is formed between two adjacent spiral sand cores 2, thereby forming a combined core mold 3 composed of all the spiral sand cores 2.

[0060] S2. Outer mold preparation: The outer mold is made according to the external dimensions of the impeller product;

[0061] S3. Molding and casting: The outer mold is placed in the sand box to form the outer mold sand pattern. Then, the combined core mold 3 is removed from the conical base 1 and placed into the outer mold sand pattern. After the box is closed, the casting mold is formed. Next, molten stainless steel is injected into the casting mold through the gating system until the casting is completed.

[0062] S4. Unpacking and Sand Removal: After the casting has cooled and solidified, open the sand box, remove the sand, and take out the formed impeller casting.

[0063] According to some embodiments of this application, please refer to Figures 1 to 6 This embodiment relates to a method for casting a stainless steel impeller, including the following steps:

[0064] S1. Core mold assembly: Provide a conical base 1 and at least three spiral sand cores 2. Hoist and install each spiral sand core 2 onto the conical base 1 in sequence, so that the inner sidewall of each spiral sand core 2 fits and is positioned against the outer conical surface of the conical base 1. Then, assemble and fix all the spiral sand cores 2 in sequence along the circumference of the conical base 1, so that a forming gap 21 that matches the blade profile of the impeller is formed between two adjacent spiral sand cores 2, thereby forming a combined core mold 3 composed of all the spiral sand cores 2.

[0065] S2. Outer mold preparation: The outer mold is made according to the external dimensions of the impeller product;

[0066] S3. Molding and casting: The outer mold is placed in the sand box to form the outer mold sand pattern. Then, the combined core mold 3 is removed from the conical base 1 and placed into the outer mold sand pattern. After the box is closed, the casting mold is formed. Next, molten stainless steel is injected into the casting mold through the gating system until the casting is completed.

[0067] S4. Unpacking and Sand Removal: After the casting has cooled and solidified, open the sand box, remove the sand, and take out the formed impeller casting.

[0068] The conical base 1 can be precision machined from steel or cast iron, with its cone angle matching the taper of the impeller hub, and its surface smooth and wear-resistant. The spiral sand core 2 is made from casting sand such as coated sand through a special core box, and its inner surface is a precisely machined inverted cone surface.

[0069] During assembly, the operator uses lifting equipment (crane or electric hoist mounted on a gantry crane) to lift the first spiral sand core 2 to the side of the conical base 1. The position is adjusted so that the inner conical surface of the first spiral sand core 2 contacts the outer conical surface of the base. Then, under gravity or a slight tangential thrust applied by the operator, the spiral sand core 2 slides along the conical surface until its lower end contacts the base platform or positioning stop, completing the initial positioning. In this manner, the second, third, and all spiral sand cores 2 are placed around the conical base 1 in sequence. Once all spiral sand cores 2 are in place, they can be fastened together using fixing components (such as metal clamps, binding straps, or special clamps) to form a combined core mold 3. The combined core mold 3 is a frustum shape, narrower at the top and wider at the bottom. At this point, the gap between the sides of adjacent spiral sand cores 2 is the forming gap 21, which perfectly matches the shape of the blade. Subsequently, the outer mold sand pattern of the impeller is made according to standard procedures. Next, loosen the constraint between the combined core mold 3 and the conical base 1, and lift the formed combined core mold 3 as a whole (for this purpose, a special lifting tool or fixing structure can be used to lock it before lifting). Transfer and accurately place it in the center of the cavity of the outer mold sand mold (specifically, during the process of lowering the combined core mold 3 into the outer mold sand mold, the axial and radial dual positioning can be achieved by the cooperation of the central positioning pin set at the bottom of the outer mold sand mold and the central hole at the bottom of the combined core mold 3; a laser alignment instrument can also be used to assist in calibration to ensure that the combined core mold 3 is located in the center of the mold). After closing the mold, pour in molten stainless steel (the molten stainless steel can be austenitic stainless steel, martensitic stainless steel or duplex stainless steel, and its pouring temperature is preferably controlled between 1550℃ and 1620℃ to ensure good fluidity and solidification structure). The molten metal fills the space between the outer mold cavity and the outer surface of the combined core mold 3 and flows into each forming gap 21. After solidification, it forms the impeller blades. After cooling, open the mold and destroy and remove the spiral sand core 2 to obtain the impeller casting.

[0070] Unlike existing technologies, the above technical solution introduces a conical base 1 with an outer conical surface as a unified installation reference for all helical sand cores 2. The inner sidewalls of all helical sand cores 2 are fitted with the precise outer conical surface of the conical base 1, thereby obtaining a unified and accurate radial and axial positioning reference. This method simplifies the complex positioning problem of multiple independent helical sand cores 2 in three-dimensional space into a problem of fitting and circumferentially arranging along a defined conical surface, ensuring the consistency of the relative positions of all helical sand cores 2, and thus ensuring the precise dimensions and correct profile of the molding gap 21 formed between adjacent helical sand cores 2. After assembly and fixing, only the combined core mold 3 is removed as a whole, and the conical base 1 can be reused, balancing accuracy and efficiency.

[0071] like Figure 1 As shown, in step S1, one side of the conical base 1 has a lower height, forming an entrance area 11 for the spiral sand core 2 to enter; during installation, each spiral sand core 2 is hoisted to the entrance area 11 in sequence, enters through the area, and then moves to the designated position along the outer conical surface of the conical base 1.

[0072] Specifically, due to its structural design or placement, the conical base 1 has one side of its bottom plane lower to form a lower-height entry area 11, facilitating the entry of the spiral sand core 2 into the circumference of the conical base 1, and then its sliding along the complete conical surface to the working position. This essentially utilizes the structural drop to create an unobstructed passage.

[0073] The width of the entrance area 11 must be at least greater than the maximum radial thickness of a single spiral sand core 2 to ensure that all spiral sand cores 2 can smoothly enter through the entrance area 11. The operation procedure is as follows: After the first spiral sand core 2 enters through the entrance area 11, it is moved to a designated starting position and fixed. The second spiral sand core 2 then enters through the same entrance area 11 and, depending on the position of the first spiral sand core 2, moves clockwise or counterclockwise along the conical base 1 until its side is in close contact with the first spiral sand core 2. All subsequent spiral sand cores 2 follow the same logic, entering through the entrance area 11 in sequence and moving to a designated position close to the previously positioned spiral sand core 2, thus completing the circumferential arrangement of all spiral sand cores 2. Throughout the process, the direction of movement (clockwise or counterclockwise) of all spiral sand cores 2 must remain consistent.

[0074] Thus, the conical base 1, with its lower structural design on one side, naturally forms a low entrance without compromising the integrity of the conical surface. This provides an extremely convenient radial channel for the installation of the spiral sand core 2, allowing the spiral sand core 2 to be easily pushed into the circumference of the conical base 1, significantly reducing the operational difficulty and interference risk of hoisting and positioning.

[0075] According to some embodiments of this application, optionally, the inlet region 11 is located at the circumferential starting position of the conical base 1.

[0076] The width of the inlet area 11 is preferably slightly greater than the sum of the maximum radial thickness of a single helical sand core 2 and the necessary operating clearance; for example, it can be slightly greater than the radial thickness of two helical sand cores 2. This width allows the first helical sand core 2 to slide in and rest against the side, while providing ample space for the entry and passage of subsequent helical sand cores 2. When the conical base 1 is fixed to the assembly platform by the positioning device, its lowest point (i.e., the inlet area 11) is set to point towards the 0° reference direction. During operation, the first helical sand core 2 easily enters from this lower side inlet, and its specific side contacts the pre-set axial positioning stop at the inlet, thus automatically completing precise initial circumferential positioning.

[0077] By aligning the lower-side entrance area 11 with the circumferential starting point, the first installed spiral sand core 2 can directly reach its precise starting position upon entry. This ingenious integration of the entrance and positioning reference functions simplifies the structure and ensures a unique and accurate angular reference for assembly.

[0078] According to some embodiments of this application, optionally, the step of moving to the designated position is completed by manual pushing until the inner sidewall of each spiral sand core 2 is completely fitted and positioned with the outer conical surface of the conical base 1.

[0079] Because of the high smoothness of the conical surface and the precise matching of the inner surface of the spiral sand core 2, the frictional resistance is very small when manually pushing it. The operator usually supports both sides of the sand core with both hands and applies a steady pushing force along the circumferential tangential direction. The spiral sand core 2 can then move smoothly and controllably along the conical surface. The operator can judge whether the fit is complete by feeling and observing the contact gap.

[0080] In this way, by utilizing the self-guiding effect of the conical base 1, precise positioning can be achieved by manually pushing the spiral sand core 2 to the designated position.

[0081] According to some embodiments of this application, optionally, in step S1, all the spiral sand cores 2 assembled on the conical base 1 are fixed from the top.

[0082] In this embodiment, one fixing method involves setting a connecting part at the top of adjacent spiral sand cores 2 and connecting them with bolts, thereby fixing all spiral sand cores 2 together. In other preferred embodiments, a top center pressing method is adopted: an annular flange with an inner hole shape adapted to the outer contour of the top of the combined core mold 3 is used as a pressure plate, which is placed on top of all the spiral sand cores 2 that are already in place; then, several long bolts are used, which pass through the evenly distributed holes on the pressure plate and are screwed downward into the threaded holes fixed to the top center or peripheral platform of the conical base 1; by tightening all the bolts evenly in a cross sequence, the annular pressure plate generates a uniform downward pressure, acting on the upper end face of each spiral sand core 2, thereby firmly pressing all the spiral sand cores 2 onto the conical surface of the conical base 1. This method ensures the uniformity of pressure distribution through the rigid pressure plate, which can effectively prevent the edge damage of the sand core due to excessive local pressure, or the slight tilting of the spiral sand core 2 due to uneven pressure, thereby ensuring the overall geometric accuracy of the combined core mold 3.

[0083] In this way, by fixing all the spiral sand cores 2 assembled on the conical base 1 at the top, the combined core mold 3 is prevented from shifting due to loosening during subsequent transfer or handling, thus ensuring the integrity and rigidity of the structure of the combined core mold 3 before and after detaching from the conical base 1.

[0084] According to some embodiments of this application, optionally, the fixing step specifically includes: first, local fixing at the side joint of two adjacent spiral sand cores 2; then, overall fixing of all spiral sand cores 2 assembled on the conical base 1 from the top.

[0085] Step 1 (Partial Fixation): Apply a special high-temperature casting adhesive to the contact seams on the sides of every two adjacent spiral sand cores 2, or use metal / plastic connecting buckles or hooks pre-embedded on the sides of the spiral sand cores 2 for mechanical interlocking, or connect them with bolts using side connecting columns. The purpose of this step is to establish a preliminary connection between the spiral sand cores 2 that can resist shear forces before the combined core mold 3 bears external loads such as hoisting, forming a stable internal skeleton. Step 2 (Overall Fixation): After the adhesive has initially cured or all side mechanical connections are completed, perform the above-mentioned overall top clamping fixation.

[0086] Thus, a step-by-step fixing strategy of "partial connection first, then overall locking" is adopted. Partial side fixing (such as bonding, snap-fitting, or bolting) first constrains adjacent spiral sand cores 2, initially forming a stable network structure; the subsequent overall top fixing provides the final strong clamping force. This method greatly enhances the overall deformation resistance of the combined core mold 3.

[0087] According to some embodiments of this application, optionally, the spiral sand core 2 is provided with a guide structure on its side. When the spiral sand core 2 moves along the outer conical surface of the conical base 1, the guide structure is used to cooperate with the corresponding structure on the adjacent spiral sand core 2 or the conical base 1 to guide it to slide to the designated position.

[0088] For example, a continuous T-shaped convex rail (guide convex ridge) can be machined along its height direction on one side of each spiral sand core 2; while a matching T-shaped groove (guide groove) can be machined on the side of the adjacent spiral sand core 2. When the spiral sand core 2 moves along the conical surface, the convex rail is embedded in the groove, forming a sliding pair, thereby precisely guiding the spiral sand core 2 to move along a predetermined path and achieving precise circumferential positioning. The guide structure can also be set between the spiral sand core 2 and the conical base 1, such as setting a guide strip on the conical surface or opening a corresponding guide groove on the inner wall of the spiral sand core 2.

[0089] Thus, the guiding structure (such as protrusions and grooves) provides a mechanical guide for the circumferential movement of the spiral sand core 2, making the sliding process smooth, precise and without swaying, significantly reducing the reliance on manual pushing skills, improving assembly efficiency, and ensuring the fit of the mating surfaces of adjacent spiral sand cores 2.

[0090] According to some embodiments of this application, optionally, in step S1, positioning marks are provided on the mating surfaces of the spiral sand core 2 and / or the conical base 1, and during assembly, the spiral sand core 2 is judged to have reached the designated position by aligning with the positioning marks.

[0091] One implementation involves laser-etching helical reference lines or equal-angle graduation lines corresponding to the blade profile distribution of the target impeller onto the smooth outer conical surface of the conical base 1; alignment marks are also provided at corresponding positions on the inner wall of the helical sand core 2. During assembly, the operator only needs to adjust the marks on the helical sand core 2 to coincide with the corresponding reference lines on the conical base 1. In some embodiments, bright, heat-resistant paint lines (such as white or yellow) are applied to specific axial and circumferential positions on the outer conical surface of the conical base 1. Alternatively, numbers, letters, or symbols can be used for numbering, for example, marking "A1, A2, A3…" on the conical surface and marking the corresponding helical sand core 2 with the same symbols. In other embodiments, a miniature proximity switch can be installed at a preset position on the conical base 1, and a metal sensing plate can be installed at a corresponding position on the helical sand core 2. When the helical sand core 2 moves to the correct position, the sensing plate triggers the switch, and an indicator light illuminates or a buzzer sounds.

[0092] In this way, positioning marks (such as scale lines and color marks) provide an intuitive visual alignment standard, enabling operators to quickly and objectively judge whether the assembly is in place, thus achieving standardization of the operation process and helping to ensure the consistency of product accuracy under different batches and different personnel operations.

[0093] According to some embodiments of this application, optionally, the number of spiral sand cores 2 is 5-7.

[0094] Spiral sand cores 2 are evenly distributed on the conical base 1. Preferably, six spiral sand cores 2 are provided, evenly distributed on the conical base 1, with a center angle of 60° between adjacent spiral sand cores 2. The complex outer surface of each spiral sand core 2 accurately replicates the two curved surfaces (pressure surface and suction surface) of a complete blade of the impeller. After the six spiral sand cores 2 are assembled and locked, six evenly distributed, spiral forming gaps 21 are formed between them. After pouring, the molten metal simultaneously fills these six gaps, forming the six blades of the impeller in one step.

[0095] In this way, 5-7 spiral sand cores 2 can form a uniformly distributed spiral channel inside the casting, effectively avoiding the channel sparseness and insufficient flow caused by too few cores, or the structural complexity and casting difficulties caused by too many cores, thereby ensuring the smooth flow of fluids (such as gas and liquid) and heat exchange efficiency.

[0096] According to some embodiments of this application, please refer to Figures 1 to 6 This embodiment also relates to a stainless steel impeller casting device, including a conical base 1, at least three spiral sand cores 2, and a fixing component. The outer surface of the conical base 1 is a conical surface for positioning. Each spiral sand core 2 is arranged around the conical base 1, and its inner sidewall is attached to the outer conical surface of the conical base 1. A forming gap 21 adapted to the blade profile of the impeller is formed between two adjacent spiral sand cores 2, which together constitute a combined core mold 3. This is used to fix all the attached spiral sand cores 2 together to form a combined core mold 3.

[0097] The conical base 1 serves as the foundation and positioning reference of the device, and its core feature is that it has an outer conical surface.

[0098] The inner wall of the spiral sand core 2 is machined to perfectly match the outer conical surface of the conical base 1, ensuring a precise fit between the two. Multiple spiral sand cores 2 are arranged around the conical base 1, and the outer walls of the multiple spiral sand cores 2 together form the complete flow channel shape of the impeller.

[0099] The function of the fixing component is to connect and lock all the positioned spiral sand cores 2 together to form a combined core mold 3 with sufficient rigidity, which can be safely hoisted and used as a whole. The fixing component can be any mechanical or chemical connection component that can fix multiple spiral sand cores 2 into a whole, such as an annular pressure plate, clamp, binding strap, tie rod, side connector, or adhesive. In this embodiment, the fixing component can be a side connector, such as pre-embedded buckles, connecting hooks, or connecting columns on the sides of adjacent spiral sand cores 2, and initial fixing is achieved by fastening or bolting during assembly. In other embodiments, the fixing component is a combination of an annular pressure plate and bolts: the annular pressure plate covers the top of all spiral sand cores 2 and is connected to the conical base 1 or bottom platform by bolts. Tightening the bolts generates uniform downward pressure, firmly pressing all the sand cores together. This method of fixing is reliable, has good overall rigidity, and can effectively prevent the sand cores from shifting during hoisting, making it suitable for occasions with high precision requirements and repetitive production. In other embodiments, the fixing component can also be a high-strength binding strap, which is wrapped around the outer circumference of the combined core mold 3 several times, tightened by a tensioner, and secured with a buckle. This method is simple to operate, low in cost, and adaptable to sand core assemblies of different sizes and shapes, demonstrating the flexibility of the device.

[0100] The stainless steel impeller casting apparatus also includes a standard casting sand box, typically consisting of an upper and lower box, used to manufacture and hold the outer mold sand pattern of the impeller. In practical applications, the combined core mold 3 is first precisely assembled and fixed on the conical base 1. Then, at another station, the outer mold sand pattern is pounded in the sand box using the impeller's outer mold model. Subsequently, the combined core mold 3 is transferred as a whole and lowered into the outer mold sand pattern cavity in the lower box, and then the upper box is closed to complete the mold assembly. The sand box here serves as the final container for supporting the outer mold and completing the pouring process.

[0101] Unlike existing technologies, the above-described technical solution provides a device specifically designed for the aforementioned method. This device uses a conical base 1 as its core, whose conical surface provides a unified and precise positioning reference for all the spiral sand cores 2. Each spiral sand core 2 achieves self-positioning by fitting against the conical surface and is locked into a rigid whole by fixing components. This ingenious device transforms the manufacturing of the combined core mold 3 used to form complex impeller flow channels into an assembly problem around a simple cone, greatly reducing the complexity and operational difficulty of specialized tooling, ensuring high precision and repeatability of the product. Simultaneously, the conical base 1, as a reusable tooling, reduces the unit cost.

[0102] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection of the present invention. Therefore, any changes and modifications made to the embodiments described herein based on the innovative concept of the present invention, or equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, directly or indirectly applying the above technical solutions to other related technical fields, are all included within the scope of patent protection of the present invention.

Claims

1. A method for casting a stainless steel impeller, characterized in that, Includes the following steps: S1. Core Mold Assembly: A conical base and at least three spiral sand cores are provided. The spiral sand cores are hoisted and installed onto the conical base in sequence, so that the inner sidewall of each spiral sand core fits and is positioned against the outer conical surface of the conical base. Then, all the spiral sand cores are assembled and fixed in sequence along the circumference of the conical base, so that a forming gap that matches the blade profile of the impeller is formed between two adjacent spiral sand cores, thereby forming a combined core mold composed of all the spiral sand cores. S2. Outer mold preparation: The outer mold is made according to the external dimensions of the impeller product; S3. Molding and Casting: The outer mold is placed in the sand box to form an outer mold sand pattern. The combined core mold is then removed from the conical base and placed into the outer mold sand pattern. After the box is closed, a casting mold is formed. Next, molten stainless steel is injected into the casting mold through the gating system until the casting is completed. S4. Unpacking and Sand Removal: After the casting has cooled and solidified, open the sand box, remove the sand, and take out the formed impeller casting.

2. The stainless steel impeller casting method according to claim 1, characterized in that, In step S1, one side of the conical base has a lower height, forming an entrance area for the spiral sand core to enter; during installation, each spiral sand core is hoisted to the entrance area in sequence, enters through the area, and then moves to the designated position along the outer conical surface of the conical base.

3. The stainless steel impeller casting method according to claim 2, characterized in that, The entrance area is located at the circumferential starting position of the conical base.

4. The stainless steel impeller casting method according to claim 2, characterized in that, The step of "moving to the designated position" is completed by manually pushing until the inner wall of each spiral sand core is completely fitted and positioned with the outer conical surface of the conical base.

5. The stainless steel impeller casting method according to claim 1, characterized in that, In step S1, all the spiral sand cores assembled on the conical base are secured from the top.

6. The stainless steel impeller casting method according to claim 5, characterized in that, The fixing steps specifically include: first, local fixing at the side joint of two adjacent spiral sand cores; then, overall fixing of all spiral sand cores assembled on the conical base from the top.

7. The stainless steel impeller casting method according to claim 1, characterized in that, The spiral sand core is provided with a guide structure on its side. When the spiral sand core moves along the outer conical surface of the conical base, the guide structure is used to cooperate with the adjacent spiral sand core or the corresponding structure on the conical base to guide it to slide to the designated position.

8. The stainless steel impeller casting method according to claim 1, characterized in that, In step S1, positioning marks are provided on the mating surfaces of the spiral sand core and / or the conical base. During assembly, the spiral sand core is aligned with the positioning marks to determine whether it has reached the designated position.

9. The stainless steel impeller casting method according to claim 1, characterized in that, The number of spiral sand cores is 5-7.

10. A stainless steel impeller casting apparatus for implementing the method according to any one of claims 1 to 9, characterized in that, include: A conical base, wherein the outer surface of the conical base is a conical surface used for positioning; At least three spiral sand cores are arranged around the conical base, and their inner sidewalls are attached to the outer conical surface of the conical base. A molding gap adapted to the blade profile of the impeller is formed between two adjacent spiral sand cores, which together constitute a combined core mold. Fixing components are used to fix all the bonded spiral sand cores together to form a combined core mold.

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