Precision casting equipment and method for a nickel-based alloy ball valve
Patent Information
- Application Number
- CN202611123129.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-28
- Publication Date
- 2026-09-15
Smart Images
Figure CN122746431A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of investment casting technology, specifically to a precision casting equipment and method for a nickel-based alloy ball valve. Background Technology
[0002] With the increasing application of intelligent casting islands in the field of high-end equipment manufacturing, nickel-based alloy ball valves, as key fluid control components, directly determine the yield rate and delivery efficiency of the entire production line through their casting quality.
[0003] In the precision casting process, the complexity of the valve body structure, especially the uneven distribution of heat points at the junction of the flange thick wall and the flow channel, places extremely high demands on solidification control. In the precision casting of nickel-based alloy ball valves, existing molds typically use independent cylindrical risers. These risers are point-like and can only compensate for local areas of the valve body flange. However, the valve body flange is an annular thick-walled structure, and these point-like cylindrical risers cannot cover the entire circumference of the flange, resulting in a very limited compensation range. Moreover, the neck of the cylindrical riser connecting to the casting is relatively thin. When the molten metal solidifies, this thin neck often cools faster than the thick wall of the flange, causing the compensation channel to solidify and block prematurely. As a result, the thick wall area of the flange cannot receive molten metal replenishment in the later stages of solidification, which will eventually produce shrinkage cavities and porosity defects inside the flange, seriously affecting the quality of the casting. Summary of the Invention
[0004] To achieve the above objectives, the present invention provides the following technical solution: On one hand, the present invention provides a precision casting device for a nickel-based alloy ball valve, including an upper mold, a lower mold, and a core. Both the upper mold and the lower mold have forming chambers inside. After the upper mold and the lower mold are closed, they form a complete ball valve body wax mold forming cavity. The core is fixed and limited in the forming cavity of the lower mold. A riser insert is detachably assembled inside the upper mold. The end of the riser insert facing the core has an inwardly recessed annular groove. The side of the annular groove facing the core is completely open for forming an annular conformal feeding riser that fits the top surface of the valve body flange. A positioning groove is formed in the forming cavity of the lower mold. A chill is embedded in the positioning groove. The upper end of the chill is a curved surface adapted to the wall thickness of the valve body and is flush with the inner wall of the lower mold cavity. The curved end of the chill matches and fits the side wall of the flow channel of the formed ball valve body wax mold to achieve directional cooling and feeding of the hot spot.
[0005] Furthermore, the upper mold has two symmetrically opened mounting slots, which are located at both ends of the upper mold forming chamber and are connected to the forming chamber at the bottom to allow the two ends of the core to enter. Each mounting slot has a fixed clamping block and a movable clamping block at the bottom. The fixed clamping block is fixedly installed at the bottom of the mounting slot, and the movable clamping block has a slider at the upper end. The slider is slidably engaged with a sliding groove opened in the inner wall of the mounting slot. The upper mold side wall has a threaded hole, and a locking screw passes through the threaded hole and is rotatably connected to one side of the movable clamping block. The upper end of the riser insert is fixedly provided with a protrusion, which is clamped and fixed between the fixed clamping block and the movable clamping block.
[0006] Furthermore, both sides of the lower mold are provided with downward grooves. The two downward grooves are located on both sides of the lower mold forming chamber and are connected to the forming chamber at the top. A positioning plate is slidably arranged in each downward groove. The two positioning plates are located at both ends of the core. An arc groove is provided on one side of the positioning plate, and the end of the core is embedded in the arc groove.
[0007] Furthermore, the bottom of the lower mold is symmetrically provided with vertical bottom grooves, which are located directly below the lower groove and are not connected. Each bottom groove is provided with a first elastic element, the upper end of which penetrates the bottom of the lower groove and is fixedly connected to the lower side of the positioning plate.
[0008] Furthermore, the riser insert is located directly above the positioning plate. During the process of the upper mold descending and closing, the riser insert contacts the positioning plate and pushes it downward, thereby replacing the position of the positioning plate and fitting with the core.
[0009] Furthermore, the upper and lower molds have a limiting groove connected to one side of their forming cavities. One end of the core is located in the limiting groove, and a threaded hole two is provided on the side wall of the lower mold. A fixing screw is internally threaded into the threaded hole two, and one end of the fixing screw is threadedly connected to a threaded hole three at the end of the core.
[0010] Furthermore, the lower mold has symmetrically arranged movable grooves in the region near the bottom of the molding chamber. One end of the movable groove is connected to the downward groove, and the other end is connected to the positioning groove. A locking rod is slidably arranged in the movable groove. A roller is rotatably installed at one end of the locking rod near the downward groove, and the other end passes through the baffle fixedly arranged in the movable groove and is inserted into the locking hole at the bottom of the chill. A second elastic element is sleeved on the locking rod. One end of the second elastic element abuts against one side of the baffle, and the other end abuts against one side of the step on the locking rod body.
[0011] Furthermore, the positioning plate has a groove on the side facing the core, and a wedge-shaped surface is provided in the groove, which makes rolling contact with the roller.
[0012] Furthermore, sliding holes are provided on both sides of the lower mold. The end of the sliding hole away from the downward groove is open, and the end facing the downward groove is connected to a slender hole. The other end of the slender hole is connected to the downward groove. A support rod is slidably arranged in the sliding hole. One end of the support rod passes through the slender hole and extends to the lower side of the positioning plate, which is used to support the positioning plate when the positioning plate restricts the core.
[0013] Furthermore, on the other hand, the present invention also provides a precision casting method for a nickel-based alloy ball valve, comprising the following steps: S1. Insert the chill into the positioning groove in the lower mold forming cavity, insert the riser insert into the symmetrically opened mounting groove in the upper mold, and rotate the locking screw to make the locking screw drive the moving clamping block to slide, clamping and fixing the protrusion at the upper end of the riser insert between the fixed clamping block and the moving clamping block. Place the core in the lower mold, so that one end of the core is embedded in the limiting groove, and use the positioning plates located in the downward grooves on both sides of the lower mold and the support rod at the bottom to support and initially limit the other two ends of the core. S2. Screw the fixing screw from the threaded hole two on the side wall of the lower mold into the threaded hole three on the end of the core to rigidly fix the core to the lower mold; S3. Control the upper mold to move downward and the lower mold to close. During the mold closing process, the riser insert in the upper mold moves downward and contacts the positioning plate, pushing the positioning plate to overcome the resistance of the first elastic element and move downward, so that the riser insert replaces the position of the positioning plate and fits against the end face of the core. At the same time, the annular groove that is recessed inward on the end face of the riser insert towards the core cooperates with the core to form an annular conformal feeding riser cavity that fits against the top surface of the valve body flange. As the positioning plate is pushed downward, the wedge surface on it presses down synchronously and slides relative to the roller, forcing the locking rod to slide laterally along the movable groove, and finally inserting the locking rod into the locking hole at the bottom of the chill, thereby realizing the automatic locking of the chill. S4. Inject wax material into the cavity formed by the upper and lower molds. The wax material is cooled and shaped under the directional cooling effect of the chiller and the feeding effect of the riser insert, forming a ball valve body wax mold that includes the valve body flow channel and the flange top surface feeding structure. S5. Open the mold and remove the wax model of the ball valve body. Assemble the wax model, coat it with refractory material and sprinkle it with sand. After drying and hardening, remove the wax material to prepare a precision casting shell. S6. After melting the nickel-based alloy, pour it into the preheated mold shell, use chills to directionally cool the thick parts of the valve body wall, and after solidification, break the shell and clean it to obtain the nickel-based alloy ball valve casting.
[0014] Beneficial effects 1. This invention, by setting a riser insert with an annular groove in the upper mold, integrally forms an annular conformal feeding riser that closely adheres to the top surface of the flange on the valve body flange end face. This annular riser can completely cover the entire annular thick-walled hot spot of the flange, constructing a continuous and uninterrupted feeding channel. When the nickel-based alloy solidifies and shrinks, the liquid metal stored in the riser can continuously and evenly flow along the annular channel to fill the thick wall of the flange. This structural design effectively solves the problems of limited feeding range and easy breakage of traditional columnar risers, ensuring that the thick-walled area of the flange receives sufficient molten metal supply throughout the solidification process, eliminating shrinkage cavities and porosity defects caused by insufficient feeding at the flange, and improving the density of the casting.
[0015] 2. This invention features a positioning groove within the lower mold forming chamber, into which a high thermal conductivity chill is embedded. The curved end of the chill fits tightly against the thick-walled hot spot of the valve body's flow channel, directionally cooling the formed flow channel area. The chill's rapid heat conduction causes preferential cooling and solidification of the thick-walled portion of the flow channel. Combined with the continuous feeding effect of the annular riser at the flange, a temperature gradient extending from the flow channel towards the flange is established within the casting, achieving strictly ordered sequential solidification. This synergistic combination of cooling and feeding effectively solves the casting defects caused by delayed flow channel cooling and chaotic solidification rhythm in traditional processes, ensuring the uniformity and integrity of the valve body's internal structure and meeting the precision casting requirements of high-end nickel-based alloy ball valves.
[0016] 3. This invention uses a positioning plate to temporarily limit the core, achieving precise and rapid assembly of the core. During the mold closing stage, the positioning plate is driven downward by the downward pressure of the riser insert. Its side wedge-shaped surface guides the locking rod to slide laterally and insert into the chill locking hole, thereby completing the automatic locking of the chill. When the mold opens, the elastic element rebounds to achieve automatic unlocking. This structure eliminates the tedious process of manually pasting the chills separately in traditional processes, realizing the automation and standardization of chill installation. Combined with the rigid locking design of the core, it effectively ensures the positional accuracy of each component during wax injection, improving production efficiency and molding quality. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a three-dimensional schematic diagram of the mold-closed state of the present invention; Figure 3This is a three-dimensional schematic diagram of the mold opening state of the present invention; Figure 4 This is a schematic diagram of the riser insert structure of the present invention; Figure 5 This is a cross-sectional view of the lower mold structure of the present invention; Figure 6 This is a cross-sectional view of the mold-closed state of the present invention; Figure 7 This is a cross-sectional view of the positioning plate structure of the present invention; Figure 8 This is a cross-sectional view of the mounting groove structure of the present invention; Figure 9 This is a schematic diagram showing the disassembly of the core and lower mold of the present invention; Figure 10 This is a cross-sectional view of the lower mold structure of the present invention.
[0019] Reference numerals: 1. Upper mold; 11. Riser insert; 12. Annular groove; 13. Protrusion; 14. Mounting groove; 15. Fixing clamp; 16. Moving clamp; 17. Locking screw; 18. Limiting groove; 2. Lower mold; 21. Downward groove; 22. Bottom groove; 23. Positioning plate; 231. Arc groove; 232. Wedge-shaped surface; 24. First elastic element; 25. Positioning groove; 26. Movable groove; 27. Locking rod; 271. Roller; 272. Second elastic element; 28. Sliding hole; 29. Support rod; 3. Core; 4. Chill; 5. Fixing screw. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0021] The present invention will be further described below with reference to embodiments.
[0022] See attached document Figure 1-10 A precision casting device for nickel-based alloy ball valves is used for integrated wax molding of the valve body, solving the key problems of insufficient feeding of the thick-walled hot joint of the flange and uneven cooling of the hot joint of the valve body flow channel in nickel-based alloy ball valves.
[0023] The equipment consists of an upper mold 1, a lower mold 2, and a core 3. Both the upper mold 1 and the lower mold 2 have molding cavities inside. After the upper mold 1 and the lower mold 2 are closed, they form a complete wax mold molding cavity for the ball valve body. The core 3 is fixed and limited within the molding cavity of the lower mold 2.
[0024] See Figure 4 The upper mold 1 is detachably equipped with a riser insert 11. The side of the riser insert 11 facing the core 3 has an inwardly carved annular groove 12. The side of the annular groove 12 facing the core 3 is completely open. After the mold is injected with wax, the annular groove 12 can be used to make an annular feeding riser that is close to the top surface of the flange on the end face of the valve body flange corresponding to the core 3. The annular groove 12 can completely cover the thickened part of the ball valve flange. The formed annular riser can form an uninterrupted feeding path along the flange. That is, when the metal cools and shrinks and there is a shortage of material, the liquid metal left in the riser can flow continuously to the thick wall of the flange to fill the gap along this channel. When the nickel-based alloy cools and solidifies, the shrinkage is large. With the help of the annular riser to continuously supply the alloy liquid, it can effectively avoid the appearance of casting defects such as holes and porosity in the thick wall of the flange.
[0025] See Figure 9 and Figure 10 The lower mold 2 has a positioning groove 25 in its molding cavity, and a chill 4 is embedded in the positioning groove 25. The chill 4 is a metal block with a fast heat conduction speed. The upper end of the chill 4 is made into a curved surface that adapts to the wall thickness of the valve body and is flush with the inner wall of the lower mold 2 cavity. This can avoid gaps in the wax injection and unevenness in the wax model. The curved end of the chill 4 fits tightly with the side wall of the flow channel of the formed ball valve body wax model. The chill 4 can perform directional quenching of the thick-walled hot spots in the flow channel of the formed valve body. It relies on the rapid heat conduction of the chill 4 to allow the thick-walled part of the flow channel to cool and solidify first. It cooperates with the annular conformal riser at the flange. The flow channel is rapidly cooled by the chill 4, and the flange relies on the annular riser to retain the molten metal and continuously feed, forming a sequential solidification gradient, which further eliminates casting defects inside the valve body. The positioning groove 25 forms a circumferential limit on the chill 4 to prevent the chill 4 from shifting due to the impact of wax material during the wax injection process, ensuring a stable and uniform quenching effect.
[0026] refer to Figure 8 The upper mold 1 has two symmetrical mounting slots 14, which are located at both ends of the molding cavity of the upper mold 1 and are connected to the molding cavity at the bottom to allow the two ends of the core 3 to enter. Each mounting slot 14 has a fixed clamping block 15 and a movable clamping block 16 at the bottom. The fixed clamping block 15 is fixedly installed at the bottom of the mounting slot 14, and the movable clamping block 16 has a slider at the upper end. The slider slides in cooperation with the sliding groove opened in the inner wall of the mounting slot 14. The upper mold 1 has a threaded hole 1 on the side wall. The locking screw 17 passes through the threaded hole 1 and is rotatably connected to one side of the movable clamping block 16. The upper end of the riser insert 11 is fixedly provided with a protrusion 13, which is clamped and fixed between the fixed clamping block 15 and the movable clamping block 16.
[0027] During actual assembly, rotating the locking screw 17 can push the moving clamp 16 to move along the sliding groove, and cooperate with the fixed clamp 15 to clamp or loosen the protrusion 13, so as to realize the quick disassembly and replacement of the riser insert 11. The riser insert 11 can be replaced, and one mold is compatible with the production of multiple valve body models, which improves the flexible production capacity of the intelligent casting island. After the riser insert 11 is fixed, the riser insert 11 will not be displaced under the high pressure of wax injection.
[0028] See Figure 5 and Figure 10 The lower mold 2 has two downward grooves 21 on both sides. The two downward grooves 21 are located on both sides of the forming cavity of the lower mold 2 and are connected to the forming cavity at the top. A positioning plate 23 is slidably installed in each downward groove 21. The two positioning plates 23 are located at both ends of the core 3. An arc groove 231 is opened on one side of the positioning plate 23. The end of the core 3 is embedded in the arc groove 231. Under normal conditions, the positioning plate 23 extends upward into the forming cavity. The arc grooves 231 on both sides can support and limit the two ends of the core 3, realize the temporary positioning of the core 3 in the air, and ensure that the position of the core 3 does not shift, which is convenient for the subsequent fixing of the core 3. The arc groove 231 is relatively shallow and does not affect the fit between the riser insert 11 and the end face of the core 3 when the positioning plate 23 is removed from the core 3.
[0029] See Figure 5 and Figure 10 A vertical bottom groove 22 is symmetrically provided at the bottom of the lower mold 2. The bottom groove 22 is located directly below the lower groove 21 and the two are not connected. Each bottom groove 22 is provided with a first elastic member 24. The upper end of the first elastic member 24 passes through the bottom of the lower groove 21 and is fixedly connected to the lower side of the positioning plate 23. When there is no external force, the first elastic member 24 continuously lifts the positioning plate 23 upward, so that the positioning plate 23 is kept in the lifting limit position.
[0030] See Figure 5 and Figure 10Sliding holes 28 are provided on both sides of the lower mold 2. The end of the sliding hole 28 away from the downward groove 21 is open, and the end facing the downward groove 21 is connected to a narrow hole. The other end of the narrow hole is connected to the downward groove 21. A support rod 29 is slidably disposed in the sliding hole 28. The support rod 29 is equipped with an elastic plunger. When the support rod 29 is pushed inward to the support position, the elastic plunger enters the sliding hole 28 and presses against the sliding hole 28. The hole wall, relying on contact tension to form an expansion friction limit, prevents the support rod 29 from accidentally sliding outward due to vibration. One end of the support rod 29 passes through the slender hole and extends to the lower side of the positioning plate 23. Before the mold is closed, the first elastic element 24 pushes the positioning plate 23 upward and pushes the support rod 29 inward along the sliding hole 28, so that the top of the support rod 29 abuts against the bottom surface of the positioning plate 23. The support rod 29 can withstand the downward pressure of the core 3, avoiding excessive contraction of the first elastic element 24 under pressure, which would cause the positioning plate 23 to sink. Before the mold is closed and pressed down, the support rod 29 can be pulled outward by force to release the support on the positioning plate 23 without interfering with the subsequent downward retraction of the positioning plate 23.
[0031] refer to Figure 4 and Figure 9 A limiting groove 18 is connected to one side of the forming cavity of the upper mold 1 and the lower mold 2. One end of the core 3 is located in the limiting groove 18. With the help of the positioning plate 23 to restrict the core 3, the core 3 can be temporarily positioned. In addition, a threaded hole 2 is provided on the side wall of the lower mold 2. A fixing screw 5 is threadedly connected to the threaded hole 3 at the end of the core 3. After assembly, the fixing screw 5 is threadedly locked to the end of the core 3. With the help of the limiting groove 18 to limit the axial movement of the end of the core, it can prevent the core 3 from moving axially due to the impact of the high pressure wax material during wax injection. It can also prevent the core 3 from moving when the positioning plate 23 moves downward, thus ensuring the forming dimensional accuracy of the valve body flow channel.
[0032] See Figure 6 The riser insert 11 is located directly above the positioning plate 23. When the mold is closed, the upper mold 1 moves downward, and the bottom end of the riser insert 11 touches the top end of the positioning plate 23 first. The upper mold 1 continues to press down, and the riser insert 11 pushes the positioning plate 23 downward to squeeze the first elastic element 24. The positioning plate 23 slides down along the downward groove 21 and moves away, completely freeing up the middle cavity. After the upper mold 1 is closed in place, the riser insert 11 fits against the end face of the core 3. The end face of the core 3 corresponds to the position of the subsequent valve body flange forming. The recessed annular groove 12 on the riser insert 11 covers the area of the thick wall of the core 3 corresponding to the flange. The groove and the cavity inside the mold are combined to form a sealed space. Wax is then injected into it, and an annular shrinkage riser can be integrally formed at the flange position of the wax mold.
[0033] See Figure 6 and Figure 10In the lower mold 2, symmetrically transverse movable grooves 26 are provided in the area near the bottom of the molding chamber. One end of the movable groove 26 is connected to the descending groove 21, and the other end is connected to the positioning groove 25. A locking rod 27 is slidably arranged in the movable groove 26. A roller 271 is rotatably installed on one end of the locking rod 27 near the descending groove 21, and the other end passes through a baffle fixed in the movable groove 26 and is inserted into a locking hole at the bottom of the chill 4. A second elastic element 272 is sleeved on the locking rod 27. One end of the second elastic element 272 abuts against one side of the baffle, and the other end abuts against... A step is attached to the locking rod 27. A slider is provided at both the top and bottom of the step. The slider slides into the long grooves on both sides of the inner wall of the movable groove 26. The slider and the long groove form a radial guiding constraint on the locking rod 27. The locking rod 27 can only move laterally along the movable groove 26. It will not shift up or down, nor will it disengage from the movable groove 26. At the same time, when the roller 271 is not pushed, under the elastic action of the second elastic element 272, the slider is in contact with the inner wall of the long groove near the downward groove 21, so that the roller 271 is always in contact with the wedge surface 232.
[0034] In addition, see Figure 7 A groove is provided on the side of the positioning plate 23 facing the core 3. A wedge-shaped surface 232 is provided in the groove. The wedge-shaped surface 232 rolls in contact with the roller 271, and the roller 271 always stays in contact with the wedge-shaped surface 232. When the positioning plate 23 descends to its extreme, its bottom is in contact with the bottom of the descending groove 21. At this time, the roller 271 rolls to the lower end of the wedge-shaped surface 232.
[0035] In summary, during the mold closing and pressing stage, the riser insert 11 pushes the positioning plate 23 to slide downward along the descending groove 21. Simultaneously, the positioning plate 23 drives the wedge surface 232 to move downward. The wedge surface 232 presses down on the roller 271, driving the locking rod 27 to slide laterally along the movable groove 26 towards the positioning groove 25. The end of the locking rod 27 is inserted into the bottom locking hole of the chill 4, completing the automatic locking of the chill 4. During this process, the locking rod 27 translates and compresses the second elastic element 272. The second elastic element 272 continuously provides reverse elastic force to ensure that the end of the locking rod 27 always presses against the chill 4, preventing the chill 4 from loosening and shifting during the wax injection process.
[0036] During the mold opening and part removal stage, after the upper mold 1 is raised, the first elastic element 24 pushes the positioning plate 23 upward to reset, and the wedge surface 232 is raised upward simultaneously, releasing the downward pressure constraint on the roller 271. The second elastic element 272 rebounds and pushes the locking rod 27 to slide in the opposite direction. The end of the locking rod 27 comes out from the locking hole of the chill 4, releasing the locking of the chill 4. At this time, the chill 4 is tightly attached to the side wall of the hot joint of the solidified ball valve body wax mold. After unlocking, the chill 4 has no structural constraint and can be directly demolded and removed synchronously with the valve body wax mold, eliminating the need for the manual separate pasting of the chill 4 after the wax mold is formed in the traditional process.
[0037] It is worth noting that the first elastic element 24 can be an elastic telescopic rod or a compression spring, and the second elastic element 272 can be a wave spring or a butterfly spring.
[0038] On the other hand, the present invention also provides a precision casting method for a nickel-based alloy ball valve, comprising the following steps: S1. Mold pre-assembly and positioning process: The chill 4 is embedded into the pre-set positioning groove 25 inside the forming cavity of the lower mold 2. Then, the riser insert 11 is installed into the symmetrically arranged mounting groove 14 of the upper mold 1. The locking screw 17 is rotated, and the locking screw 17 drives the moving clamp 16 to slide horizontally. The fixed clamp 15 and the moving clamp 16 cooperate to clamp the protrusion 13 set on the upper end of the riser insert 11, thus completing the detachable fixing of the riser insert 11 in the upper mold 1. Then, the core 3 is placed inside the forming cavity of the lower mold 2, so that one end of the core 3 is embedded into the corresponding limiting groove 18 of the lower mold 2 to complete the single-sided limiting. At the same time, the positioning plates 23 assembled inside the downward grooves 21 on both sides of the lower mold 2 and the support rods 29 arranged at the bottom of the lower mold 2 are used to support and pre-position the remaining two ends of the core 3 to prevent the core 3 from tilting or shifting during placement.
[0039] In this step, the chill 4 is made of a high thermal conductivity metal. The upper curved surface of the chill 4 is flush with the inner wall of the molding cavity. After pre-assembly, there is no need for manual pasting of the chill 4. The riser insert 11 adopts a clamping block locking structure, which is convenient for disassembly and assembly. The combination of positioning plate 23 and support rod 29 is only used for temporary support to prevent the core 3 from swaying in the air during assembly.
[0040] S2. Rigid locking process of core 3: Based on the above S1 step, the fixing screw 5 is screwed inward from the second threaded hole opened on the side wall of the lower mold 2, and the end of the screw is screwed into the third threaded hole pre-machined at the end of the core 3. The core 3 is completely rigidly fixed in the molding cavity of the lower mold 2 through the threaded locking structure. After locking, the core 3 has no displacement or shaking and remains fixed throughout the process, eliminating the risk of core 3 displacement and deformation during subsequent mold closing and wax injection, and ensuring the dimensional accuracy of the valve body wax mold.
[0041] S3. Mold Closing Process: The upper mold 1 is driven vertically downward by the drive cylinder of the wax injection equipment to complete the precise mold closing with the lower mold 2. During the downward mold closing stage, the riser insert 11 assembled inside the upper mold 1 first contacts the top surface of the positioning plate 23. The continuous downward pressure of the upper mold 1 pushes the positioning plate 23 to slide downward, compressing the first elastic element 24 installed inside the downward groove 21. The positioning plate 23 retracts downward as a whole, completely freeing up the end face space of the core 3. At this time, the riser insert 11 continues to fall and directly adheres to the end face of the core 3 corresponding to the valve body flange forming position. The riser insert 11 is recessed inward on the side facing the core 3 to form an annular groove 12. The annular groove 12 and the end face of the core 3 surround each other to form a complete annular conformal shrinkage riser forming cavity. After wax injection, the annular shrinkage riser that is tightly attached to the top surface of the flange can be integrally formed.
[0042] During the downward sliding of the positioning plate 23, the wedge-shaped surface 232 on the side of the positioning plate 23 simultaneously presses the roller 271 downward. The wedge-shaped surface 232 and the roller 271 slide relative to each other at an angle, converting the vertical downward pressure into a horizontal thrust, which pushes the locking rod 27 to slide laterally along the movable groove 26 inside the lower mold. The end of the locking rod 27 is finally inserted into the locking hole reserved at the bottom of the chill 4. The chill 4 is automatically locked and fixed by the mold closing action, without the need for manual locking of the chill 4. After the mold is opened, the second elastic element 272 rebounds and automatically releases the locking of the chill 4.
[0043] S4. Wax Injection Molding Process: Molten wax is injected into the complete sealed cavity formed by the closing of the upper mold 1 and the lower mold 2. During the filling and flow process, the wax directly and tightly fits the curved surface of the pre-locked chill 4. The chill relies on its high thermal conductivity to perform directional quenching on the hot spot area of the thick wall of the flow channel, controlling the flow channel to cool and solidify preferentially. At the same time, the annular riser structure formed by the core 3 and the annular groove 12 can store a sufficient amount of wax. After the corresponding casting is formed, the stored molten metal is used for the flange thick wall feeding. Under the dual action of directional quenching of the chill 4 and synergistic feeding of the annular riser, the wax gradually and uniformly cools and solidifies, forming a complete ball valve body wax model with valve body flow channel structure and flange top annular feeding structure.
[0044] S5. Shell preparation process: After the mold is opened, the wax model is taken out together with the chill 4. The chill 4 is tightly attached to the outside of the thick wall of the flow channel of the valve body wax model. Multiple valve body wax models are welded and assembled onto the pouring channel to complete the assembly operation. Then, the whole module is repeatedly coated with multiple layers of refractory slurry and evenly sprinkled with refractory sand. After each layer is coated, it is dried and hardened at low temperature. Multiple layers of refractory material are stacked to wrap the entire wax model and the chill 4 attached to the wax model, so that the chill 4 is completely embedded and fixed inside the refractory coating. After all coating and drying are completed, a high-temperature dewaxing process is used to completely melt out and discharge the wax material inside the module, finally forming a precision casting shell with a hollow interior and the chill 4 fixedly embedded in the inner wall of the flow channel.
[0045] S6. Melting and Casting Process: The nickel-based alloy raw material is melted at high temperature in a melting furnace, and impurities are removed by thorough stirring. The prepared mold shell is preheated in an oven to eliminate internal moisture and raise the temperature of the cavity wall. The molten nickel-based alloy is then smoothly poured into the preheated hollow cavity of the mold shell. Simultaneously, the integrally formed annular riser wax on the wax pattern is removed, forming an annular riser cavity connecting the mold shell flange. During casting, the molten metal simultaneously fills both the valve body cavity and the annular riser cavity. During the casting stage, the casting is firmly embedded... The chill 4 on the inner wall of the mold shell continuously provides directional quenching to the thick-walled area of the valve body flow channel, rapidly dissipating heat from the thick-walled area and allowing the thick-walled area of the valve body flow channel to solidify preferentially. The flange area relies on the sufficient amount of liquid nickel-based alloy stored in the cavity of the annular riser to continuously replenish the gaps generated by the solidification shrinkage of the alloy, forming a uniform and orderly sequential solidification gradient, completing the overall solidification and molding of the valve body. After the casting is completely cooled, the outer refractory mold shell is broken, and the casting is shot-blasted, ground, and inspected to remove the gating riser, flash, and burrs, ultimately obtaining a high-precision nickel-based alloy ball valve casting without shrinkage cavities or porosity defects.
[0046] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.
Claims
1. A precision casting device for a nickel-based alloy ball valve, comprising an upper mold (1), a lower mold (2), and a core (3), wherein both the upper mold (1) and the lower mold (2) have forming chambers inside, and the upper mold (1) and the lower mold (2) are closed to form a complete ball valve body wax mold forming cavity, and the core (3) is fixed and limited within the forming cavity of the lower mold (2), characterized in that, The upper mold (1) is detachably fitted with a riser insert (11). The riser insert (11) has an annular groove (12) recessed inward on the end facing the core (3). The annular groove (12) is fully open on the side facing the core (3) for forming an annular conformal shrinkage riser that fits the top surface of the valve body flange. The lower mold (2) has a positioning groove (25) in the forming cavity. A chill (4) is embedded in the positioning groove (25). The upper end face of the chill (4) is a curved surface that adapts to the wall thickness of the valve body and is flush with the inner wall of the lower mold (2) cavity. The curved end of the chill (4) matches and fits the side wall of the flow channel of the formed ball valve body wax mold to achieve directional cooling and shrinkage of the hot spot.
2. The precision casting apparatus for a nickel-based alloy ball valve according to claim 1, wherein The upper mold (1) has two symmetrical mounting slots (14). The two mounting slots (14) are located at both ends of the molding chamber of the upper mold (1) and are connected to the molding chamber at the bottom so that the two ends of the core (3) can enter. Each mounting slot (14) has a fixed clamping block (15) and a movable clamping block (16) at the bottom. The fixed clamping block (15) is fixedly installed at the bottom of the mounting slot (14). The movable clamping block (16) has a slider at the top. The slider slides in cooperation with the sliding groove opened on the inner wall of the mounting slot (14). The upper mold (1) has a threaded hole. The locking screw (17) passes through the threaded hole and is rotatably connected to one side of the movable clamping block (16). The upper end of the riser insert (11) is fixedly provided with a protrusion (13). The protrusion (13) is clamped and fixed between the fixed clamping block (15) and the movable clamping block (16).
3. The precision casting apparatus for a nickel-based alloy ball valve according to claim 1, wherein The lower mold (2) has two downward grooves (21) on both sides. The two downward grooves (21) are located on both sides of the forming cavity of the lower mold (2) and are connected to the forming cavity at the top. Each downward groove (21) has a slidable positioning plate (23). The two positioning plates (23) are located at both ends of the core (3). An arc groove (231) is opened on one side of the positioning plate (23), and the end of the core (3) is embedded in the arc groove (231).
4. The precision casting apparatus for a nickel-based alloy ball valve according to claim 3, characterized by, The bottom of the lower mold (2) is symmetrically provided with vertical bottom grooves (22). The bottom grooves (22) are located directly below the down groove (21) and the two are not connected. Each bottom groove (22) is provided with a first elastic element (24). The upper end of the first elastic element (24) penetrates the bottom of the down groove (21) and is fixedly connected to the lower side of the positioning plate (23).
5. The precision casting apparatus for a nickel-based alloy ball valve according to claim 4, wherein The riser insert (11) is located directly above the positioning plate (23). During the process of the upper mold (1) descending and closing, the riser insert (11) contacts the positioning plate (23) and pushes it downward, thereby replacing the position of the positioning plate (23) and fitting with the core (3).
6. The precision casting apparatus for a nickel-based alloy ball valve according to claim 5, wherein The upper mold (1) and the lower mold (2) have a limiting groove (18) connected to one side of their forming cavity. One end of the core (3) is located in the limiting groove (18) and a threaded hole is provided on the side wall of the lower mold (2). A fixing screw (5) is threadedly connected to the threaded hole. One end of the fixing screw (5) is threadedly connected to the threaded hole three at the end of the core (3).
7. The precision casting apparatus for a nickel-based alloy ball valve according to claim 6, wherein The lower mold (2) has a symmetrically arranged movable groove (26) in the area near the bottom of the molding chamber. One end of the movable groove (26) is connected to the downward groove (21), and the other end is connected to the positioning groove (25). A locking rod (27) is slidably arranged in the movable groove (26). A roller (271) is rotatably installed at one end of the locking rod (27) near the downward groove (21), and the other end passes through the baffle fixed in the movable groove (26) and is inserted into the locking hole at the bottom of the chill (4). A second elastic element (272) is sleeved on the locking rod (27). One end of the second elastic element (272) abuts against one side of the baffle, and the other end abuts against one side of the step on the locking rod (27).
8. The precision casting equipment for a nickel-based alloy ball valve according to claim 7, characterized in that, The positioning plate (23) has a groove on the side facing the core (3), and a wedge-shaped surface (232) is provided in the groove. The wedge-shaped surface (232) rolls in contact with the roller (271).
9. The precision casting equipment for a nickel-based alloy ball valve according to claim 8, characterized in that, The lower mold (2) has sliding holes (28) on both sides. The end of the sliding hole (28) away from the downward groove (21) is open, and the end facing the downward groove (21) is connected to a slender hole. The other end of the slender hole is connected to the downward groove (21). A support rod (29) is slidably arranged in the sliding hole (28). One end of the support rod (29) passes through the slender hole and extends to the lower side of the positioning plate (23) to support the positioning plate (23) when the positioning plate (23) restricts the core (3).
10. A precision casting method for a nickel-based alloy ball valve, characterized in that, Includes the following steps: S1. Insert the chill (4) into the positioning groove (25) in the forming cavity of the lower mold (2), insert the riser insert (11) into the mounting groove (14) symmetrically opened in the upper mold (1), and rotate the locking screw (17) so that the locking screw (17) drives the moving clamp (16) to slide, clamp and fix the protrusion (13) at the upper end of the riser insert (11) between the fixed clamp (15) and the moving clamp (16), place the core (3) in the lower mold (2), so that one end of the core (3) is embedded in the limiting groove (18), and use the positioning plate (23) in the downward groove (21) on both sides of the lower mold (2) and the support rod (29) at the bottom to support and initially limit the other two ends of the core (3); S2. Screw the fixing screw (5) into the threaded hole 2 opened on the side wall of the lower mold (2) and into the threaded hole 3 opened at the end of the core (3) to rigidly fix the core (3) on the lower mold (2); S3. Control the upper mold (1) to move downward and close the lower mold (2). During the mold closing process, the riser insert (11) in the upper mold (1) moves downward and contacts the positioning plate (23), pushing the positioning plate (23) to overcome the resistance of the first elastic element (24) and move downward, so that the riser insert (11) replaces the position of the positioning plate (23) and fits against the end face of the core (3). At the same time, the annular groove (12) of the riser insert (11) facing the end face of the core (3) is recessed inward and cooperates with the core (3) to form an annular conformal feeding riser cavity that fits against the top surface of the valve body flange. During the process of the positioning plate (23) being pushed downward, the wedge surface (232) on it is pressed down synchronously and slides relative to the roller (271), forcing the locking rod (27) to slide laterally along the movable groove (26), and finally the locking rod (27) is inserted into the locking hole at the bottom of the chill (4) to realize the automatic locking of the chill (4). S4. Wax material is injected into the cavity formed by the upper mold (1) and the lower mold (2). The wax material is cooled and shaped under the directional cooling effect of the chiller (4) and the feeding effect of the riser insert (11), forming a ball valve body wax mold containing the valve body flow channel and the flange top surface feeding structure. S5. Open the mold and remove the wax model of the ball valve body. Assemble the wax model, coat it with refractory material and sprinkle it with sand. After drying and hardening, remove the wax material to prepare a precision casting shell. S6. After melting the nickel-based alloy, pour it into the preheated mold shell, use chills (4) to directionally cool the thick part of the valve body wall, and clean it after solidification to obtain the nickel-based alloy ball valve casting.