Split sand box, precision casting process of impeller rotor and impeller rotor

Abstract

The application discloses a split sand box, a precision casting process of an impeller rotor and the impeller rotor. The sand box comprises a box body, a bottom of which is provided with a molding hole; a base having a concave cavity, a positioning groove for positioning and placing a mold shell is arranged on the base, and the base is used for matching connection with the bottom of the box body, so that the connection position of the mold shell and the pouring gate is matched with the position of the molding hole; a movable assembly used for controlling opening of the molding hole and also used for controlling closing of the molding hole and radial positioning of a connecting part on the pouring gate for connecting the mold shell; and a supporting assembly used for supporting the box body to keep the box body standing on a working plane after the base is removed. Molding sand is filled into the box body, so that the molding sand falls into the concave cavity of the base through the molding hole until covering the mold shell. The movable assembly is used for closing the molding hole and ensuring accurate positioning of the mold shell in the sand box, so that the mold shell is located at the central position of the sand box, and then uniform filling sand amount of each batch of products and consistency of temperature field and heat dissipation boundary conditions in the pouring process and stability of the casting process are ensured.

Description

Technical Field

[0001] This invention relates to the field of investment casting technology for impeller rotors, and in particular, to a split-type sand box, a precision casting process for impeller rotors, and an impeller rotor. Background Technology

[0002] Precision castings of aero-engine impeller rotors mainly consist of hubs and blades. The exhaust edge of the blades is relatively thin (about 0.4 mm) and the overall dimensional accuracy of the blade body is high, so it is impossible to add risers and gating gates. Therefore, the structure of the precision casting gating system for this type of casting is basically the same, with a large frustum-shaped gating gate set on the upper hub column.

[0003] To reduce heat loss during the melting and casting process, ensure the integrity of the blade filling, and maintain the stability of the mold shell, one of the mainstream solutions currently in use is to use integral sand filling molding, which involves placing the entire mold shell into a sand box and then filling the entire sand box with refractory and heat-insulating molding sand.

[0004] The existing casting method has many shortcomings, including at least the following problems:

[0005] (1) The positioning accuracy of the mold shell is low. During the molding operation, the center of gravity of the mold is biased upwards and the hub column is small, which makes it easy to wobble. The mold shell is placed in the sand box with poor consistency and uneven sand filling, resulting in large differences in temperature field and heat dissipation boundary conditions. Ultimately, this leads to poor casting process stability and large fluctuations in product quality.

[0006] (2) The entire runner and part are covered by molding sand, which is conducive to filling during the casting process, but heat dissipation is difficult and temperature control is poor after casting. The flow channel surface and blade body of the part are prone to shallow looseness. Summary of the Invention

[0007] This invention provides a split-type sand box, a precision casting process for impeller rotors, and an impeller rotor to solve the technical problems of poor process stability and shallow porosity in impeller rotor castings.

[0008] The technical solution adopted in this invention is as follows:

[0009] A split-type sand box, used for precision casting molds of impeller rotors, the sand box comprising:

[0010] A box body is used to hold ceramic pouring cups, sprues, and molding sand. A molding hole is provided at the bottom of the box body.

[0011] The base has a cavity for accommodating the mold shell and molding sand. The cavity has a positioning groove for positioning the mold shell. The base is used to match and connect with the bottom of the box body so that the connection position of the mold shell and the gating system matches the position of the molding hole.

[0012] An active component, disposed in the housing, is used to control the opening of the bottom molding hole of the housing, and also to control the closing of the bottom molding hole of the housing while radially positioning the connecting part on the gating system for connection with the mold shell;

[0013] A support assembly is provided on the housing to support the housing and, after the base is removed, to keep the housing upright on the working plane.

[0014] As a further improvement to the above technical solution, the box body is provided with a force-applying structure, which is used to lift the box body after an external force is applied, thereby causing the shell to detach from the base.

[0015] As a further improvement to the above technical solution, the movable component includes two symmetrically arranged movable inserts. The bottom of the box body is provided with a movable groove communicating with the molding hole for installing the movable inserts. The movable insert is provided with a positioning groove at one end facing the gating, which matches the half-circumference outer diameter of the connection part of the gating, so that when the two movable inserts are inserted into the movable groove and abut against each other, the positioning groove surrounds the connection part of the gating.

[0016] As a further improvement to the above technical solution, a limiting protrusion is provided in the movable groove, and a guide groove is provided in the movable insert plate along the insertion direction. The limiting protrusion is used to insert into the guide groove to restrict the movement direction of the movable protrusion.

[0017] As a further improvement to the above technical solution, a handle is provided at the end of the movable insert plate facing outward from the gating channel.

[0018] As a further improvement to the above technical solution, the support component includes a support column disposed at the bottom of the box, the height of the support column being matched with the height of the base, and the base having through holes or support grooves at corresponding positions of the support column that match the outer diameter of the support column; the support columns are evenly distributed at the bottom of the box and located outside the movement path of the movable component.

[0019] As a further improvement to the above technical solution, the diameter of the molding hole is larger than the outer diameter of the opening of the pouring cup.

[0020] According to another aspect of the present invention, a precision casting process for an impeller rotor is also provided, which utilizes any of the split sand boxes described above, the casting process comprising the following steps:

[0021] S1. Place the mold shell into the recessed cavity of the base, and insert the lower hub column part of the mold shell into the positioning groove;

[0022] S2. The active component controls the opening of the molding hole, placing the box on the base so that the pouring cup and runner are located inside the box;

[0023] S3. Fill the base with molding sand;

[0024] S4. The active component closes the shaping hole channel;

[0025] S5. Fill the molded sand into the box;

[0026] S6. Melting and casting;

[0027] S7. Lift the box body until the shell is detached from the chassis, and place the box body on the working surface supported by the support components;

[0028] S8. Preset time for heat dissipation when the shell part is suspended.

[0029] As a further improvement to the above technical solution, in step S3, molding sand is filled until it is flush with the upper surface of the base; in step S5, molding sand is filled until it is flush with the upper surface of the box.

[0030] According to another aspect of the present invention, an impeller rotor is also provided, which applies the precision casting process for impeller rotors described above.

[0031] This invention has the following beneficial effects: In use, the mold shell is placed in the recessed cavity of the base and positioned vertically by the positioning groove. A movable component opens the molding hole of the box, placing the box on the base. The gating system connects to the upper hub column of the mold shell, and the pouring cup connects to the gating system. Molding sand is filled into the box, falling through the molding hole into the recessed cavity of the base until it covers the mold shell. The movable component closes the molding hole while ensuring precise positioning of the mold shell within the sand box, placing it in the center of the box. This ensures uniform sand filling for each batch of products and optimal temperature field and heat dissipation boundary conditions during casting. Consistency and casting process stability significantly reduce product quality fluctuations; molding sand is filled into the box and base for investment casting. During the casting process, the shell and gating system are fully encased in molding sand, ensuring the filling of the thin-walled blade portion; after casting, the box is lifted to detach the shell from the base, and the base is placed on the working plane and supported by the support components to maintain its upright position. The gating system is still encased in molding sand for heat preservation, while the workpiece portion of the shell is suspended to dissipate heat, thus forming a temperature gradient and enhancing the feeding effect of the gating system on the thicker parts of the impeller hub. This solves the problem of looseness on the workpiece flow channel surface and the shallow surface of the blade, ensuring that there are no defects of excessive looseness in the hub area.

[0032] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0033] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 This is a bottom view of the preferred embodiment of the present invention with the shaped hole in the open state;

[0035] Figure 2 This is a front view of the preferred embodiment of the present invention with the shaped hole in the open state;

[0036] Figure 3 This is a schematic diagram of the internal structure of the shaped hole in the open state according to a preferred embodiment of the present invention;

[0037] Figure 4 This is a cross-sectional view of the shaped hole in the closed state according to a preferred embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of the box structure with the shaped hole closed, according to a preferred embodiment of the present invention. Figure 1 ;

[0039] Figure 6 This is a schematic diagram of the box structure with the shaped hole closed, according to a preferred embodiment of the present invention. Figure 2 ;

[0040] Figure 7 This is a schematic diagram of the bottom structure of the preferred embodiment of the present invention with the shaping hole closed;

[0041] 1. Box body 11. Molding hole 12. Lug 13. Movable groove 14. Limiting protrusion 2. Base 21. Cavity 22. Positioning groove 3. Movable insert plate 31. Positioning groove 32. Guide groove 33. Handle 4. Support component 5. Sprue cup 6. Sprue 7. Mold shell 71. Upper wheel hub column part 72. Lower wheel hub column part. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] Reference Figures 1 to 7 A preferred embodiment of the present invention provides a split-type sand box for precision casting of impeller rotors, the sand box comprising:

[0044] Box 1 is used to hold ceramic pouring cup 5, pouring channel 6 and molding sand. Molding hole 11 is provided at the bottom of box 1.

[0045] The base 2 is used to be set at the bottom of the box body 1. The base 2 has a cavity 21 for accommodating the shell 7 and molding sand. The cavity 21 has a positioning groove 22 for positioning the shell 7. The base 2 is used to match and connect with the bottom of the box body 1 so that the connection position of the shell 7 and the sprue 6 matches the position of the molding hole 11.

[0046] An active component, located in the housing 1, is used to control the opening of the bottom molding hole 11 of the housing 1, and also to control the closing of the bottom molding hole 11 of the housing 1 while radially positioning the connecting part on the gating 6 for connection with the mold shell 7.

[0047] Support component 4 is provided on the housing 1 to support the housing 1, thereby supporting the housing 1 so that the housing 1 remains upright on the working plane after the base 2 is removed.

[0048] Among them, the mold shell 7 is used to form the workpiece mold, and its shape and structure match the impeller rotor. The impeller rotor includes an upper hub column, a hub, blades, and a lower hub column; the pouring cup 5 and the gating channel 6 form the gating system.

[0049] Understandably, when using this split-type sand box, the mold shell 7 is placed in the recessed cavity of the base 2, and positioned by the positioning groove 22 to keep the mold shell 7 upright. The molding hole 11 of the box body 1 is opened by the movable component, and the box body 1 is placed on the base 2. The sprue 6 is connected to the upper hub column part 71 of the mold shell 7, and the pouring cup 5 is connected to the sprue 6. Molding sand is filled into the box body 1 and falls into the recessed cavity of the base 2 through the molding hole 11 until it covers the mold shell 7. The molding hole 11 is closed by the movable component, which at the same time ensures that the mold shell 7 is accurately positioned in the sand box, so that the mold shell 7 is in the center of the sand box. This ensures that the amount of sand filled in each batch of products is uniform and that the temperature field and dispersion are controlled during the pouring process. Consistent thermal boundary conditions and stable casting process significantly reduce product quality fluctuations. Molding sand is filled into the housing 1 and base 2, and investment casting can then be performed. During the casting process, the shell 7 and the gating system are fully wrapped by the molding sand, ensuring that the thin-walled blade portion is filled. After casting, the housing 1 is lifted to detach the shell 7 from the base 2. The base 2 is placed on the working plane and supported by the support component 4 to maintain its upright position. The gating system is still wrapped by the molding sand for heat preservation, while the workpiece portion of the shell 7 is suspended to dissipate heat, thus forming a temperature gradient and enhancing the feeding effect of the sprue 6 on the thicker parts of the impeller hub. This solves the problem of looseness on the workpiece flow channel surface and the shallow surface of the blade, ensuring that there are no defects of excessive looseness in the hub area.

[0050] In this embodiment, the box body 1 is provided with a force-applying structure, which is used to lift the box body 1 after an external force is applied, thereby causing the shell 7 to detach from the base 2; specifically, the force-applying structure is a lug 12 formed on the upper end of the box body 1 in a symmetrical distribution, and the box body 1 is lifted by hooking the two lugs 12 respectively through the hook of the lifting equipment.

[0051] In this embodiment, the movable component includes two symmetrically arranged movable insert plates 3. The bottom of the housing 1 is provided with a movable groove 13 that communicates with the molding hole 11 for installing the movable insert plates 3. The end of the movable insert plate 3 facing the gating 6 is provided with a positioning groove 31 that matches the semi-circular outer diameter of the connecting part of the gating 6. So when the two movable insert plates 3 are inserted into the movable groove 13 and abut against each other, the positioning groove 31 surrounds the connecting part of the gating 6. The connecting part of the gating 6 is cylindrical, that is, the two positioning grooves 31 are semi-circular, and when combined, they are circular, matching the connecting part.

[0052] In this embodiment, a limiting protrusion 14 is provided in the movable groove 13, and a guide groove 32 is provided in the movable insert plate 3 along the insertion direction. The limiting protrusion 14 is used to insert into the guide groove 32 to limit the movement direction of the movable protrusion, preventing the movable insert plate 3 from being directly pulled out of the movable groove 13. At the same time, it ensures that when the movable insert plate 3 is inserted to the end position, the positioning groove 31 and the positioning groove 22 are coaxial, and the end positions of the two movable insert plates 3 in the insertion direction are in a matching abutment position, thereby ensuring the consistency and accuracy of the radial positioning of the shell 7. In conjunction with the positioning groove 22, the upper and lower ends of the shell 7 are radially positioned respectively to prevent swaying, ensure that each batch of workpieces is accurately positioned, and ensure the stability of the casting process.

[0053] In this embodiment, a handle 33 is provided at the end of the movable insert plate 3 facing outward from the gating channel 6, so as to control the movement of the movable insert plate 3 within the movable groove 13.

[0054] In this embodiment, the support component 4 includes a support column disposed at the bottom of the housing 1. The height of the support column matches the height of the base 2. The base 2 has through holes or support grooves at the corresponding positions of the support column that match the outer diameter of the support column. In this embodiment, a through hole is used as an example. The support columns are evenly distributed at the bottom of the housing 1 and are located outside the movement path of the movable component. When the housing 1 is placed on the base 2, the support columns and through holes are used for positioning. When the housing 1 is detached from the base 2, the support columns support the housing 1 so that the shell 7 is suspended to dissipate heat.

[0055] In this embodiment, the diameter of the molding hole 11 is larger than the outer diameter of the opening of the pouring cup 5. The outer diameter of the opening of the pouring cup is usually larger than the outer diameter of the runner. After matching and connecting the runner 6 with the shell 7 and installing the pouring cup 5, the diameter of the molding hole 11 is larger than the outer diameter of the opening of the pouring cup 5. Then the box 1 can be installed so that the pouring cup 5 and the runner 6 pass through the molding hole 11 in sequence and the box 1 abuts against the base 2.

[0056] On the other hand, this embodiment also provides a precision casting process for an impeller rotor, which uses the above-mentioned split sand box and includes the following steps:

[0057] S1. Place the housing 7 in the recess of the base 2, and insert the lower hub column portion 72 of the housing 7 into the positioning groove 22 to initially position the housing 7 and keep the housing 7 upright.

[0058] S2. Place the box 1 on the base 2, open the molding hole 11 controlled by the movable component, place the box 1 on the base 2, so that the pouring cup 5 and the runner 6 are located inside the box 1;

[0059] Specifically, after the sprue 6 and the pouring cup 5 are installed, the two movable insert plates 3 are pulled outward to make the molding hole 11 fully open. The box body 1 is lifted above the base 2 by the lifting equipment through the lug 12, so that the radial positions of the molding hole 11 and the shell 7 are roughly matched. The box body 1 is lowered so that the pouring cup 5 and the sprue 6 pass through the molding hole 11 into the box body 1 in sequence, so that the support column and the through hole are aligned, and the box body 1 and the base 2 are coaxial. After the box body 1 is completely lowered, the box body 1 abuts against the base 2 and the support column is inserted into the through hole.

[0060] In some embodiments, the box 1 may be positioned on the base 2 before the gating channel 6 and the pouring cup 5 are matched and installed.

[0061] S3. Fill the base 2 with molding sand;

[0062] Specifically, molding sand is filled into the box 1 and then passes through the molding hole 11 into the base 2. It can be understood that the molding sand is filled until it is flush with the upper surface of the base 2 to cover the shell 7 and ensure the casting effect.

[0063] S4. Close the shaping hole 11 channel of the active component;

[0064] Specifically, insert two movable insert plates 3 until they abut against each other, and simultaneously position the shell 7 radially to prevent swaying and keep the shell 7 on the axis of the sand box. It should be noted that during the process of filling the molding sand in step S3, the movable component is inserted and opened at least once to position the shell 7 radially before the molding sand is filled, so as to prevent the positioning of the shell 7 from being obstructed and the operation from being inconvenient after the sand is filled.

[0065] S5. Fill the molding sand into box 1;

[0066] Similarly, fill the molding sand until it is flush with the upper surface of the box 1, and the opening end of the pouring cup 5 is above the upper surface of the box 1.

[0067] S6. Melting and casting;

[0068] S7. Lift the box body 1 to the shell 7 to detach it from the chassis, and place the box body 1 on the working plane to be supported by the support assembly 4;

[0069] Specifically, after the box body 1 is lifted by hooking the hoisting equipment onto the lug 12, the shell 7 is separated from the molding sand in the base 2. The sand box is placed on a flat ground and supported by the support column, so that the workpiece part of the shell 7 is suspended to dissipate heat, while the casting system part is still kept warm in the molding sand in the sand box.

[0070] S8. Preset time for suspended heat dissipation of part 7 of the shell.

[0071] Specifically, the heat dissipation time is set according to the material and size specifications of the workpiece.

[0072] This casting process ensures that the thin blade portion is filled during the pouring process, and at the same time, the workpiece is partially suspended to dissipate heat after pouring, forming a temperature gradient. This solves the problem of looseness on the flow channel surface and shallow surface of the blade, and enhances the feeding effect of the sprue 6 on the thick part of the impeller hub. The resulting impeller rotor hub has no defects of excessive looseness.

[0073] On the other hand, this embodiment also provides an impeller rotor that uses the above-mentioned precision casting process for impeller rotors.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A split-type sand box, characterized in that, The sand box is used for the precision casting mold of the impeller rotor, and the sand box includes: The box (1) is used to hold the ceramic pouring cup (5), the pouring channel (6) and the molding sand. The bottom of the box (1) is provided with molding holes (11). The base (2) has a cavity (21) for accommodating the shell (7) and molding sand. The cavity (21) has a positioning groove (22) for positioning the shell (7). The base (2) is used to match and connect with the bottom of the box (1) so that the connection position of the shell (7) and the gating (6) matches the position of the molding hole (11). An active component is provided on the box (1) for controlling the opening of the bottom molding hole (11) of the box (1) and for controlling the closing of the bottom molding hole (11) of the box (1) while radially positioning the connecting part on the gating (6) for connecting with the shell (7). A support component (4) is provided on the housing (1) to support the housing (1) and thus support the housing (1) so that the housing (1) remains upright on the working plane after the base (2) is removed.

2. The split-type sand box according to claim 1, characterized in that, The box (1) is provided with a force-applying structure, which is used to lift the box (1) after an external force is applied, thereby causing the shell (7) to detach from the base (2).

3. The split-type sand box according to claim 1, characterized in that, The movable component includes two symmetrically arranged movable inserts (3). The bottom of the box (1) is provided with a movable groove (13) communicating with the molding hole (11) for installing the movable inserts (3). The movable inserts (3) are provided with a positioning groove (31) at one end facing the gating (6) that matches the half-circumferential outer diameter of the connection part of the gating (6), so that when the two movable inserts (3) are inserted into the movable groove (13) and abut against each other, the positioning groove (31) surrounds the connection part of the gating (6).

4. The split-type sand box according to claim 3, characterized in that, The movable groove (13) is provided with a limiting protrusion (14), and the movable insert plate (3) is provided with a guide groove (32) along the insertion direction. The limiting protrusion (14) is used to insert into the guide groove (32) to restrict the movement direction of the limiting protrusion (14).

5. The split-type sand box according to claim 3, characterized in that, The movable insert plate (3) is provided with a handle (33) at one end facing outward from the gating channel (6).

6. The split-type sand box according to claim 1, characterized in that, The support component (4) includes a support column disposed at the bottom of the box (1). The height of the support column matches the height of the base (2). The base (2) has through holes or support grooves that match the outer diameter of the support column at the respective positions corresponding to the support column. The support columns are evenly distributed at the bottom of the box (1) and located outside the movement path of the movable component.

7. The split-type sand box according to claim 1, characterized in that, The diameter of the shaping hole (11) is larger than the outer diameter of the opening of the pouring cup (5).

8. A precision casting process for an impeller rotor, characterized in that, The casting process using the split sand box according to any one of claims 1-7 includes the following steps: S1. Place the mold shell into the recessed cavity of the base, and insert the lower hub column part of the mold shell into the positioning groove; S2. The active component controls the opening of the molding hole, placing the box on the base so that the pouring cup and runner are located inside the box; S3. Fill the base with molding sand; S4. The active component closes the shaping hole channel; S5. Fill the molded sand into the box; S6. Melting and casting; S7. Lift the box body until the shell is detached from the chassis, and place the box body on the working surface supported by the support components; S8. Preset time for heat dissipation when the shell part is suspended.

9. The precision casting process for the impeller rotor according to claim 8, characterized in that, In step S3, fill with molding sand until the molding sand is flush with the upper surface of the base; in step S5, fill with molding sand until the molding sand is flush with the upper surface of the box.

10. An impeller rotor, characterized in that, The impeller rotor precision casting process described in any one of claims 8-9 is applied.

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