Preparation method of wax mold of impeller with spiral curved surface gradient runner

Abstract

The invention relates to the technical field of investment casting, in particular to a wax mold preparation method of an impeller with a spiral curved surface gradient runner, which comprises the following steps: S1, preparing a plurality of runner core blocks by adopting a water-soluble material according to the shape of the runner in the impeller; s2, a plurality of runner core blocks are placed in a forming mold to be positioned and combined; s3, wax is injected into the forming mold, a wax pattern is pressed, and a wax pattern assembly with a runner core block is obtained; and S4, the runner core block in the wax mold assembly is corroded, and the whole wax mold of the impeller is obtained. The method provided by the invention is suitable for preparing the integral wax mold with the spiral curved surface gradient runner impeller.

Description

Technical Field

[0001] The invention relates to the technical field of investment casting, and in particular to a method for preparing a wax mold of an impeller with a spiral curved surface and a gradually changing flow channel. Background Art

[0002] At present, the common impeller structure adopts a design with a flow channel shape of equal cross-section, or a blade design adopts a straight blade design, that is, the flow channel shape and the blade do not have a spiral gradient. For conventional impellers, when making wax models, the flow channel part of the wax model can be formed by core pulling or segmented core pulling.

[0003] However, for Figure 1 , Figure 2 As for the impeller with spiral surface gradual flow channel shown in the figure, the impeller has multiple spiral surface gradual flow channels, A in the figure represents the outer end opening of the flow channel, B represents the inner end opening of the flow channel, the horizontal dimension from the outer end opening A to the inner end opening B gradually decreases, the vertical dimension gradually increases, and the blade shape is a spiral surface. It is impossible to design core pulling and segmented core pulling from the outer end opening A and the inner end opening B. How to prepare the wax mold of the impeller with spiral surface gradual flow channel is an urgent problem to be solved. Summary of the invention

[0004] The main purpose of the present invention is to provide a wax mold preparation method for an impeller with a spiral curved surface and a gradually changing flow channel, aiming to solve the above-mentioned technical problems.

[0005] To achieve the above object, the present invention provides a method for preparing a wax mold of an impeller having a spiral curved surface and a gradually changing flow channel, comprising the following steps:

[0006] S1. According to the shape of the flow channel in the impeller, a plurality of flow channel core blocks are prepared using water-soluble materials;

[0007] S2, placing a plurality of runner core blocks in a molding die for positioning and combining;

[0008] S3, injecting wax into the molding mold, pressing the wax pattern, and obtaining a wax pattern assembly with a runner core block;

[0009] S4. The flow channel core block in the wax model assembly is dissolved to obtain an integral wax model of the impeller.

[0010] Preferably, each of the runner core blocks includes a runner forming part, an axial positioning plate located at the outer end of the runner forming part, and a radial positioning block located at the inner end of the runner forming part and extending downward; when all the runner core blocks are placed in the molding mold for assembly, all the radial positioning blocks are combined to form a splicing positioning column, and a splicing positioning hole is formed in the center of the formed splicing positioning column.

[0011] Preferably, the molding mold includes, from bottom to top, a base plate, a molding plate, an upper template and a cover plate; two positioning blocks are movably installed on the base plate, and the two positioning blocks are symmetrically arranged at 180 degrees; semicircular positioning recesses are respectively arranged on the opposite end faces of the two positioning blocks; a first wedge-shaped groove is arranged on the top surface of the positioning block; a molding hole is arranged at the center position of the molding plate, and two first wedge-shaped blocks are fixedly installed on the lower end surface of the upper template; in the step S2, when multiple flow channel core blocks are positioned and combined, the splicing positioning column formed by the combination of all radial positioning blocks passes through the molding hole in the center of the molding plate and rests on the top surface of the base plate; after the upper template is buckled on the molding plate, the first wedge block is inserted into the first wedge-shaped groove of the positioning block, and pushes the two positioning blocks to move inward, and the positioning recesses of the two positioning blocks embrace the outer peripheral surface of the splicing positioning column.

[0012] Preferably, a positioning core column is provided on the countersunk hole in the center of the top surface of the base plate, and the positioning core column is fastened to the base plate by a first screw, and the first screw passes through the stepped hole in the center of the base plate from bottom to top and is screwed into the threaded hole in the center of the bottom surface of the positioning core column; the upper part of the positioning core column is higher than the top surface of the base plate; the orifice of the splicing positioning hole formed in the center of the splicing positioning column is provided with a chamfer; in the step S2, when positioning and combining multiple flow channel core blocks, the upper part of the positioning core column is inserted into the splicing positioning hole formed in the center of the splicing positioning column.

[0013] Preferably, the molding mold also includes a core rod for molding the central through hole of the impeller wax mold; the core rod is a stepped columnar structure, the diameter of which gradually increases from bottom to top, and comprises a molding section, a plug-in section, an axial limiting section and a pressure-bearing section in sequence; a guiding cone is provided at the edge position of the lower end of the molding section; a core fixing hole is provided at the center of the top surface of the positioning core column; when the molding mold is closed, the lower end of the molding section is inserted into the core fixing hole of the positioning core column; the plug-in section cooperates with the central through hole of the upper mold plate and the cover plate; the lower end surface of the axial limiting section abuts against the top surface of the cover plate.

[0014] Preferably, two pressure blocks are installed on the top surface of the cover plate; when the molding mold is closed, the end surface of the top end of the core rod is flush with the top surface of the pressure block.

[0015] Preferably, two first rectangular sinks are provided on the top surface of the base plate; the two first rectangular sinks are symmetrically arranged at 180 degrees; the positioning block is slidably matched with the first rectangular sink; a T-shaped slide hole is provided on the bottom wall of the first rectangular sink, and a screw sleeve is slidably installed in the T-shaped slide hole; a second screw is passed through the screw sleeve, and the upper end of the second screw is threadedly connected with the positioning block; a rectangular groove is provided on the bottom surface of the forming plate; the positioning block is slidably matched with the rectangular groove; and clearance notches are respectively provided on both side surfaces of the forming plate to make way for the first wedge block.

[0016] Preferably, a first guide column is inlaid at two diagonal positions on the top surface of the base plate, and a first guide sleeve is inlaid at two diagonal positions on the bottom surface of the forming plate, and the upper end of the first guide column is inserted into the first guide sleeve when the mold is closed; a second guide column is inlaid at two diagonal positions on the top surface of the forming plate, and a second guide sleeve is inlaid at two diagonal positions on the bottom surface of the upper template, and the upper end of the second guide column is inserted into the second guide sleeve when the mold is closed; a third guide column is inlaid at two diagonal positions on the top surface of the upper template, and a third guide sleeve is inlaid at two diagonal positions on the bottom surface of the cover plate, and the upper end of the third guide column is inserted into the third guide sleeve when the mold is closed.

[0017] Preferably, two second rectangular sinks are provided on the top surface of the forming plate, and a second movable block is slidably installed in the second rectangular sinks, and a second wedge-shaped groove is provided on the top surface of the second movable block; two second wedge blocks are fixedly installed on the lower end surface of the upper template; when the upper template is buckled on the forming plate, the second wedge block is inserted into the second wedge-shaped groove of the second movable block, and the wedge surface of the second wedge block matches the wedge surface of the second wedge groove.

[0018] Preferably, an annular sink is jointly provided on the top surface of the molding plate and the second movable block for supporting the axial positioning plate of the runner core block; a plurality of circumferential positioning blocks are inlaid on the edge of the annular sink; a circumferential positioning groove is provided on the outer circumferential surface of the axial positioning plate of the runner core block; in the step S2, when the plurality of runner core blocks are positioned and combined, the circumferential positioning blocks cooperate with the circumferential positioning grooves on the runner core blocks for positioning.

[0019] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0020] (1) In the present invention, a plurality of flow channel core blocks are prepared by using a water-soluble material, and the plurality of flow channel core blocks are placed in a molding mold for positioning and combination; wax is injected into the molding mold, and a wax pattern is pressed to obtain a wax pattern assembly with flow channel core blocks; the flow channel core blocks in the wax pattern assembly are dissolved to obtain an integral wax pattern of an impeller. The method provided by the present invention is suitable for preparing an integral wax pattern of an impeller with a spiral curved surface and a gradually changing flow channel.

[0021] (2) In the present invention, through the structural design of the flow channel core block and the molding mold, the molding mold can position multiple flow channel core blocks conveniently and accurately, thereby improving the overall wax film quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the structure of an impeller with a spiral curved surface and a gradually changing flow channel;

[0024] Figure 2 It is a cross-sectional view of an impeller having a spiral curved surface and a gradually changing flow channel;

[0025] Figure 3 It is a schematic diagram of the structural decomposition of the forming mold in the present invention;

[0026] Figure 4 It is a schematic diagram of positioning a plurality of flow channel core blocks by the molding die in the present invention;

[0027] Figure 5 A schematic diagram of the structure of the wax pattern assembly with the flow channel core block prepared by the present invention;

[0028] Figure 6 A top view of the molding die in the present invention;

[0029] Figure 7 for Figure 6 Cross-sectional view along CC;

[0030] Figure 8 for Figure 6 Rotated view after sectioning along BB;

[0031] Fig. 9 It is a structural schematic diagram of the forming plate in the present invention;

[0032] Fig.10 It is a structural schematic diagram of the upper template in the present invention;

[0033] Fig.11 Schematic diagram of the flow channel core block in the present invention Figure 1 ;

[0034] Fig.12 Schematic diagram of the flow channel core block in the present invention Figure 2 ;

[0035] Fig.13 It is a schematic diagram of a plurality of flow channel core blocks being spliced ​​together in the present invention;

[0036] Fig.14 It is a schematic diagram of all the flow channel core blocks in the present invention after being spliced ​​together;

[0037] Fig.15 It is a structural schematic diagram of the core rod in the present invention;

[0038] Fig.16 It is a perspective effect diagram of the forming mold in the present invention.

[0039] Description of the accompanying drawings: 1. flow channel core block; 1a. flow channel forming part; 1b. axial positioning plate; 1c. radial positioning block; 1d. splicing positioning column; 1e. splicing positioning hole; 1f. circumferential positioning groove; 2. bottom plate; 2a. first rectangular sink; 3. forming plate; 3a. rectangular groove; 3b. clearance gap; 3c. second rectangular sink; 4. upper template; 5. cover plate; 6. positioning movable block; 6a. positioning depression; 6b. first wedge groove; 7. first wedge block; 8. positioning core column; 9. first screw; 10. Screw sleeve; 11. Second screw; 12. First guide post; 13. First guide sleeve; 14. Second guide post; 15. Second guide sleeve; 16. Third guide post; 17. Third guide sleeve; 18. Mandrel; 18a. Forming section; 18b. Insertion section; 18c. Pressure section; 18d. Guide cone; 18e. Axial limiting section; 19. Pressure block; 20. Second movable block; 20a. Second wedge-shaped groove; 21. Second wedge-shaped block; 22. Annular sink; 23. Circumferential positioning block; 24. Horizontal wax injection hole. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0042] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0043] Combination Figures 3 to 16 As shown, a wax mold preparation method of an impeller with a spiral curved surface and a gradually changing flow channel comprises the following steps:

[0044] S1. According to the shape of the flow channel in the impeller, a plurality of flow channel core blocks 1 are prepared using water-soluble materials;

[0045] S2, placing a plurality of flow channel core blocks 1 in a molding die for positioning and combining;

[0046] S3, injecting wax into the molding mold, pressing the wax pattern, and obtaining a wax pattern assembly with a runner core block 1;

[0047] S4, dissolving the flow channel core block 1 in the wax model assembly to obtain an integral wax model of the impeller.

[0048] Combination Figures 11 to 14 As shown, each runner core block 1 includes a runner forming part 1a, an axial positioning plate 1b located at the outer end of the runner forming part 1a, and a radial positioning block 1c located at the inner end of the runner forming part 1a and extending downward; when all the runner core blocks 1 are placed in the molding mold for assembly, all the radial positioning blocks 1c are combined to form a splicing positioning column 1d, and a splicing positioning hole 1e is formed in the center of the formed splicing positioning column 1d.

[0049] Combination Figure 3 to Figure 4As shown, the molding die includes, from bottom to top, a bottom plate 2, a molding plate 3, an upper mold plate 4 and a cover plate 5; two positioning blocks 6 are movably mounted on the bottom plate 2, and the two positioning blocks 6 are symmetrically arranged at 180 degrees; semicircular positioning recesses 6a are respectively arranged on the opposite end surfaces of the two positioning blocks 6; a first wedge-shaped groove 6b is arranged on the top surface of the positioning block 6; a molding hole is arranged at the center position of the molding plate 3, and two first wedge-shaped blocks 7 are fixedly mounted on the lower end surface of the upper mold plate 4; in the step S2, a plurality of flow channel cores are When the block 1 is positioned and assembled, the splicing positioning column 1d formed by the combination of all radial positioning blocks 1c passes through the forming hole in the center of the forming plate 3 and abuts against the top surface of the bottom plate 2, thereby forming axial positioning for the splicing positioning column 1d; after the upper template 4 is buckled onto the forming plate 3, the first wedge block 7 is inserted into the first wedge groove 6b of the positioning movable block 6, and the wedge surface of the first wedge block 7 cooperates with the wedge surface of the first wedge groove 6b to push the two positioning movable blocks 6 to move inward, and the positioning recesses 6a of the two positioning movable blocks 6 embrace the outer peripheral surface of the splicing positioning column 1d and are newly positioned.

[0050] Combination Figures 3 to 8 ,as well as Fig.14 As shown, a positioning core column 8 is arranged on the countersunk hole at the center of the top surface of the bottom plate 2, and the positioning core column 8 is fastened to the bottom plate 2 by a first screw 9, and the first screw 9 passes through the stepped hole at the center of the bottom plate 2 from bottom to top and is screwed on the threaded hole at the center of the bottom surface of the positioning core column 8; the upper part of the positioning core column 8 is higher than the top surface of the bottom plate 2; the opening of the splicing positioning hole 1e formed at the center of the splicing positioning column 1d is provided with a chamfer; in the step S2, when positioning and assembling multiple flow channel core blocks 1, the upper part of the positioning core column 8 is inserted into the splicing positioning hole 1e formed at the center of the splicing positioning column 1d, which further plays the role of centering the splicing positioning column 1d. In addition, when the positioning recesses 6a of the two positioning movable blocks 6 embrace the splicing positioning column 1d, a radial inward force will be generated, and at the same time, since the positioning core column 8 plays a limiting role, the radial positioning block 1c can be prevented from being deformed.

[0051] Combination Figure 3 , Figure 7 , Figure 8 as well as Fig.15As shown, the molding die also includes a core rod 18, which is used to mold the central through hole of the impeller wax mold; the core rod 18 is a stepped columnar structure, with a diameter gradually increasing from bottom to top, and includes a molding section 18a, a plug section 18b, an axial limit section 18e and a pressure section 18c in sequence; a guiding cone 18d is provided at the edge position of the lower end of the molding section 18a; a centering hole 8a is provided at the center of the top surface of the positioning core column 8; when the molding die is closed, the lower end of the molding section 18a is inserted into the centering hole 8a of the positioning core column 8 to play a positioning role; the plug section 18b cooperates with the central through hole of the upper mold plate 4 and the cover plate 5; the lower end surface of the axial limit section 18e abuts against the top surface of the cover plate 5. Further, two pressure blocks 19 are installed on the top surface of the cover plate 5; when the molding die is closed, the end surface of the top of the core rod 18 is flush with the top surface of the pressure block 19. The molding die is placed on the platform of the wax injection machine during wax injection, and the wax injection is performed after the upper pressing plate of the wax injection machine is pressed against the pressure block 19 and the top of the mandrel 18. Therefore, the end surface of the top of the mandrel 18 needs to be flush with the top surface of the pressure block 19.

[0052] Combination Figure 3 As shown, two first rectangular sinks 2a are provided on the top surface of the base plate 2; the two first rectangular sinks 2a are symmetrically arranged at 180 degrees; the positioning block 6 is slidably matched with the first rectangular sink 2a; a T-shaped slide hole 2b is provided on the bottom wall of the first rectangular sink 2a, and a screw sleeve 10 is slidably installed in the T-shaped slide hole 2b; a second screw 11 is passed through the screw sleeve 10, and the upper end of the second screw 11 is threadedly connected with the positioning block 6; a rectangular groove 3a is provided on the bottom surface of the forming plate 3; the positioning block 6 is slidably matched with the rectangular groove 3a; and clearance notches 3b are respectively provided on both side surfaces of the forming plate 3 to make way for the first wedge block 7.

[0053] Combination Figure 3 As shown, first guide posts 12 are inlaid at two diagonal positions on the top surface of the bottom plate 2, first guide sleeves 13 are inlaid at two diagonal positions on the bottom surface of the molding plate 3, and the upper end of the first guide post 12 is inserted into the first guide sleeve 13 when the mold is closed; second guide posts 14 are inlaid at two diagonal positions on the top surface of the molding plate 3, and second guide sleeves 15 are inlaid at two diagonal positions on the bottom surface of the upper mold plate 4, and the upper end of the second guide post 14 is inserted into the second guide sleeve 15 when the mold is closed; third guide posts 16 are inlaid at two diagonal positions on the top surface of the upper mold plate 4, and third guide sleeves 17 are inlaid at two diagonal positions on the bottom surface of the cover plate 5, and the upper end of the third guide post 16 is inserted into the third guide sleeve 17 when the mold is closed. Through this structure, the mutual assembly positions between the bottom plate 2, the molding plate 3, the upper mold plate 4, and the cover plate 5 are guaranteed.

[0054] Combination Figure 3 , Figure 8As shown, two second rectangular sinks 3c are arranged on the top surface of the molding plate 3, and a second movable block 20 is slidably installed in the second rectangular sink 3c, and a second wedge-shaped groove 20a is arranged on the top surface of the second movable block 20; two second wedge-shaped blocks 21 are fixedly installed on the lower end surface of the upper template 4; after the upper template 4 is buckled on the molding plate 3, the second wedge-shaped block 21 is inserted into the second wedge-shaped groove 20a of the second movable block 20, and the wedge-shaped surface of the second wedge-shaped block 21 matches the wedge-shaped surface of the second wedge-shaped groove 20a. By setting the second movable block 20, after the wax mold is pressed in step S3 to obtain a wax mold assembly with a flow channel core block 1, when the mold is opened, after the upper template 4 and the cover plate 5 are removed, and then the second movable block 20 is pulled out radially outward, the wax mold assembly with the flow channel core block 1 is conveniently taken out by utilizing the space formed by the second rectangular sink 3c, so after the second movable block 20 is pulled out, the second rectangular sink 3c forms an operating space.

[0055] Combination Figure 3 , Figure 4 As shown, an annular sink 22 is commonly provided on the top surfaces of the forming plate 3 and the second movable block 20 for supporting the axial positioning plate 1b of the runner core block 1; a plurality of circumferential positioning blocks 23 are inlaid on the edge of the annular sink 22; a circumferential positioning groove 1f is provided on the outer peripheral surface of the axial positioning plate 1b of the runner core block 1; in the step S2, when the plurality of runner core blocks 1 are positioned and combined, the circumferential positioning blocks 23 cooperate with the circumferential positioning groove 1f on the runner core block 1 for positioning.

[0056] Combination Figure 7 As shown, the top surface of the upper template 4 and the bottom surface of the cover plate 5 are respectively provided with grooves with semicircular cross-sections. After the mold is closed, the two grooves form a complete horizontal wax injection hole 24. The opening of the horizontal wax injection hole 24 is set as a cone surface to facilitate matching with the wax injection head of the wax injection machine. A semicircular vertical wax injection groove 25 is provided on the side wall of the center hole of the upper template 4. The upper end of the vertical wax injection groove 25 is connected to the horizontal wax injection hole 24, and the lower end of the vertical wax injection groove 25 is connected to the cavity of the entire molding mold.

[0057] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a wax mold of an impeller having a spiral curved surface and a gradually changing flow channel, characterized in that: The steps include: S1. According to the shape of the flow channel in the impeller, a plurality of flow channel core blocks (1) are prepared using a water-soluble material; S2, placing a plurality of flow channel core blocks (1) in a molding die, positioning them, and combining them; S3, injecting wax into the molding mold, pressing the wax pattern, and obtaining a wax pattern assembly with a flow channel core block (1); S4. The flow channel core block (1) in the wax model assembly is dissolved away to obtain an integral wax model of the impeller.

2. The wax pattern preparation method according to claim 1, characterized in that: Each flow channel core block (1) comprises a flow channel forming portion (1a), an axial positioning plate (1b) located at the outer end of the flow channel forming portion (1a), and a radial positioning block (1c) located at the inner end of the flow channel forming portion (1a) and extending downward; when all the flow channel core blocks (1) are placed in a forming mold for assembly, all the radial positioning blocks (1c) are assembled to form a splicing positioning column (1d), and a splicing positioning hole (1e) is formed at the center of the formed splicing positioning column (1d).

3. The wax pattern preparation method according to claim 2, characterized in that: The molding die comprises, from bottom to top, a bottom plate (2), a molding plate (3), an upper mold plate (4) and a cover plate (5); two positioning blocks (6) are movably mounted on the bottom plate (2), and the two positioning blocks (6) are symmetrically arranged at 180 degrees; semicircular positioning recesses (6a) are respectively arranged on opposite end surfaces of the two positioning blocks (6); a first wedge-shaped groove (6b) is arranged on the top surface of the positioning block (6); a molding hole is arranged at the center position of the molding plate (3), and two first wedge-shaped blocks (7) are fixedly mounted on the lower end surface of the upper mold plate (4); In step S2, when positioning and assembling a plurality of flow channel core blocks (1), a spliced ​​positioning column (1d) formed by combining all radial positioning blocks (1c) passes through the molding hole at the center of the molding plate (3) and abuts against the top surface of the bottom plate (2); after the upper mold plate (4) is buckled onto the molding plate (3), the first wedge block (7) is inserted into the first wedge groove (6b) of the positioning movable block (6) and pushes the two positioning movable blocks (6) to move inward, and the positioning recesses (6a) of the two positioning movable blocks (6) embrace the outer peripheral surface of the spliced ​​positioning column (1d).

4. The wax pattern preparation method according to claim 3, characterized in that: A positioning core column (8) is arranged on the countersunk hole at the center of the top surface of the base plate (2); the positioning core column (8) and the base plate (2) are fastened together by a first screw (9); the first screw (9) passes through the stepped hole at the center of the base plate (2) from bottom to top and is screwed into the threaded hole at the center of the bottom surface of the positioning core column (8); the upper part of the positioning core column (8) is higher than the top surface of the base plate (2); the opening of the splicing positioning hole (1e) formed at the center of the splicing positioning column (1d) is provided with a chamfered angle; In the step S2, when positioning and assembling a plurality of flow channel core blocks (1), the upper portion of the positioning core column (8) is inserted into the splicing positioning hole (1e) formed at the center of the splicing positioning column (1d).

5. The wax pattern preparation method according to claim 4, characterized in that: The molding die also includes a core rod (18) for molding the central through hole of the impeller wax mold; the core rod (18) is a stepped columnar structure, the diameter of which gradually increases from bottom to top, and comprises a molding section (18a), a plug-in section (18b), an axial limiting section (18e) and a pressure-bearing section (18c) in sequence; a guiding cone surface (18d) is provided at the edge position of the lower end of the molding section (18a); A core hole (8a) is provided at the center of the top surface of the positioning core column (8); When the molding die is closed, the lower end of the molding section (18a) is inserted into the core hole (8a) of the positioning core column (8); the plug-in section (18b) cooperates with the central through hole of the upper mold plate (4) and the cover plate (5); and the lower end surface of the axial limiting section (18e) abuts against the top surface of the cover plate (5).

6. The wax pattern preparation method according to claim 4, characterized in that: Two pressure blocks (19) are installed on the top surface of the cover plate (5); when the molding die is closed, the end surface of the top end of the core rod (18) is flush with the top surface of the pressure block (19).

7. The wax pattern preparation method according to claim 3, characterized in that: Two first rectangular sinks (2a) are arranged on the top surface of the bottom plate (2); the two first rectangular sinks (2a) are arranged symmetrically at 180 degrees; the positioning block (6) is slidably matched with the first rectangular sinks (2a); a T-shaped slide hole (2b) is arranged on the bottom wall of the first rectangular sink (2a), and a screw sleeve (10) is slidably installed in the T-shaped slide hole (2b); a second screw (11) is inserted into the screw sleeve (10), and the upper end of the second screw (11) is threadedly connected with the positioning block (6); a rectangular groove (3a) is arranged on the bottom surface of the forming plate (3); the positioning block (6) is slidably matched with the rectangular groove (3a); and clearance notches (3b) are respectively opened on both side surfaces of the forming plate (3) for making way for the first wedge block (7).

8. The wax pattern preparation method according to claim 3, characterized in that: First guide pillars (12) are embedded at two diagonal positions on the top surface of the bottom plate (2), and first guide sleeves (13) are embedded at two diagonal positions on the bottom surface of the molding plate (3); when the mold is closed, the upper end of the first guide pillar (12) is inserted into the first guide sleeve (13); Second guide pillars (14) are embedded at two diagonal positions on the top surface of the molding plate (3), and second guide sleeves (15) are embedded at two diagonal positions on the bottom surface of the upper mold plate (4), and the upper ends of the second guide pillars (14) are inserted into the second guide sleeves (15) when the mold is closed; Third guide pillars (16) are embedded at two diagonal positions on the top surface of the upper mold plate (4), and third guide sleeves (17) are embedded at two diagonal positions on the bottom surface of the cover plate (5). When the mold is closed, the upper end of the third guide pillar (16) is inserted into the third guide sleeve (17).

9. The wax pattern preparation method according to claim 3, characterized in that: Two second rectangular sinks (3c) are arranged on the top surface of the forming plate (3), and a second movable block (20) is slidably installed in the second rectangular sinks (3c), and a second wedge-shaped groove (20a) is arranged on the top surface of the second movable block (20); two second wedge-shaped blocks (21) are fixedly installed on the lower end surface of the upper template (4); when the upper template (4) is buckled onto the forming plate (3), the second wedge-shaped block (21) is inserted into the second wedge-shaped groove (20a) of the second movable block (20), and the wedge-shaped surface of the second wedge-shaped block (21) matches the wedge-shaped surface of the second wedge-shaped groove (20a).

10. The wax pattern preparation method according to claim 9, characterized in that: An annular sink (22) is commonly provided on the top surfaces of the forming plate (3) and the second movable block (20) for supporting the axial positioning plate (1b) of the flow channel core block (1); a plurality of circumferential positioning blocks (23) are inlaid on the edge of the annular sink (22); a circumferential positioning groove (1f) is provided on the outer peripheral surface of the axial positioning plate (1b) of the flow channel core block (1); in the step S2, when the plurality of flow channel core blocks (1) are positioned and combined, the circumferential positioning blocks (23) cooperate with the circumferential positioning grooves (1f) on the flow channel core blocks (1) for positioning.

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