Anti-gravity investment casting device suitable for titanium alloy and casting method of anti-gravity investment casting device

Abstract

The invention provides an anti-gravity investment casting device suitable for titanium alloy and a casting method of the anti-gravity investment casting device, belongs to the field of titanium alloy casting, and solves the problems that an existing anti-gravity forming device has a sealing problem and a riser tube cannot be centered with a pouring gate inlet of a mold shell. Wherein the lifting structure can drive the mold assembly to move in the vertical direction, a mold shell in the mold assembly is located in the sand box, the sand box abuts against the top face of the flange sleeve, the flange sleeve is arranged on the mold support in a sliding and penetrating mode, and the upper pressing plate abuts against the upper portion of the sand box and is connected with the mold support. The water-cooled copper crucible is located below the riser tube, a flange structure is arranged at the upper end of the riser tube, the positioning and centering structure is used for enabling a pouring gate inlet of the mold shell and the riser tube to be coaxially arranged, the sealing structure comprises a first sealing ring and a second sealing ring, the first sealing ring is located between the flange sleeve and the flange structure, and the second sealing ring is located between the flange sleeve and the flange structure. The second sealing ring is located between the flange sleeve and the middle partition plate. According to the device, the pouring gate inlet of the mold shell can be centered with the riser tube, and the lower working tank is completely sealed.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloy casting, and particularly relates to an anti-gravity investment casting device applicable to titanium alloy and a casting method thereof. Background Art

[0002] In the prior art, the patent with the authorization announcement number CN103934431B discloses an anti-gravity forming device and forming method for complex thin-walled castings of titanium and titanium alloys, aiming to solve the key problems such as the forming device being unable to achieve high-inertia environment melting required for anti-gravity forming of titanium and titanium alloys. Specifically, it is disclosed that the device includes an upper tank body, a middle partition section, a lower tank body, a hydraulic jack, a power supply, a tilting heating coil, a crucible, a vacuum system, a liquid level adjustment system, a circulating water cooling system, a melting observation mechanism, a ramming mechanism, a feeding mechanism, a temperature measuring mechanism, a riser pipe, a hydraulic drive system, a mold lifting system, a mold and a spare mold. The upper tank body and the lower tank body are separated by the middle partition section. A mold lifting system is provided in the upper tank body, and the mold and the riser pipe are located in the mold lifting system. A tilting heating coil, a crucible and a spare mold are provided in the lower tank body. The top of the riser pipe is provided with a flat flange, which is stuck in the hole at the bottom of the mold. The upper tank body is tightly sealed with the middle partition section, and the middle partition section is tightly sealed with the lower tank body. The patent application with the application publication number CN117961029A discloses a method for vacuum low-pressure investment casting of superalloys, and specifically discloses that: a flange-like structure is provided at the uppermost end of the riser pipe, which is exactly arranged at the hole on the low-pressure casting platform for placing the hole connecting the sand box and the melting device. A high-temperature gasket is also provided between the flange-like structure at the uppermost end of the riser pipe and the flange-like structure at the lower part of the mold shell.

[0003] However, these existing anti-gravity forming devices still have sealing problems. When inflating the lower working tank, gas may leak between the lower working tank and the sand box. Moreover, there is also a problem that the riser pipe and the runner inlet of the mold shell cannot be aligned. The riser pipe and the runner inlet of the mold shell are prone to misalignment, resulting in turbulent flow of the titanium alloy melt at the runner inlet of the mold shell, and causing metallurgical defects such as gas entrapment and inclusion in the casting. Summary of the Invention In view of this, in order to solve the existing sealing problems of the anti-gravity forming device and the problem that the riser pipe and the runner inlet of the mold shell cannot be aligned, the present invention provides an anti-gravity investment casting device applicable to titanium alloy and a casting method thereof.

[0004] To achieve the above object, the present invention adopts the following technical solutions: An anti-gravity investment casting device applicable to titanium alloy, comprising: An upper working tank, with a middle partition plate provided at the bottom of the upper working tank; The mold assembly is located inside the upper working tank. The mold assembly includes an upper pressure plate, a sand box, a mold shell, a flange sleeve, and a mold support. The mold shell is located inside the sand box. The pouring gate inlet of the mold shell penetrates through the bottom through hole at the center of the bottom of the sand box. The top surface of the sand box abuts against the flange sleeve. The flange sleeve is slidably penetrated through the mold support. The upper pressure plate abuts against the upper part of the sand box. The upper pressure plate is detachably connected to the mold support. The bottom surface of the flange sleeve can abut against the middle partition plate; The lifting structure is used to drive the mold assembly to move in the vertical direction; The lower working tank is located below the upper working tank and is connected to the middle partition plate; The water-cooled copper crucible and the induction coil are both located inside the lower working tank. The induction coil is arranged around the water-cooled copper crucible; A riser pipe is provided with a communication hole at the center of the flange sleeve. The riser pipe penetrates through the communication hole. The upper end of the riser pipe is provided with a flange structure. The riser pipe can penetrate through the middle partition plate. The water-cooled copper crucible is located below the riser pipe. The pouring gate inlet of the mold shell is located above the riser pipe; The positioning and centering structure is used to coaxially arrange the pouring gate inlet of the mold shell and the riser pipe; The sealing structure includes a first sealing ring and a second sealing ring. The first sealing ring is located between the flange sleeve and the flange structure. The second sealing ring is located between the flange sleeve and the middle partition plate.

[0005] As a preferred solution of the above anti-gravity investment casting device applicable to titanium alloy, the positioning and centering structure includes a positioning bottom plate, a frustum, a plurality of positioning blocks, a plurality of guiding blocks, and a sink groove provided at the center of the top surface of the flange sleeve and communicating with the communication hole. The frustum is detachably arranged on the positioning bottom plate. A plurality of positioning blocks are fixedly arranged on the positioning bottom plate. The plurality of positioning blocks are arranged at intervals around the frustum. When the sand box is placed on the positioning bottom plate, the plurality of positioning blocks all abut against the outer wall of the sand box. When the mold shell is placed inside the sand box, the frustum penetrates through the pouring gate inlet of the mold shell, and can coaxially arrange the pouring gate inlet of the mold shell and the sand box; The flange structure is embedded in the sink groove, and can coaxially arrange the riser pipe and the flange sleeve; A plurality of guiding blocks are fixedly and spacedly arranged on the mold support. When the flange sleeve is placed on the mold support and the sand box is placed on the flange sleeve, the plurality of guiding blocks all abut against the outer wall of the flange sleeve and all abut against the outer wall of the sand box, and can coaxially arrange the flange sleeve and the sand box.

[0006] As a preferred solution of the above anti-gravity investment casting device applicable to titanium alloy, the guiding block is provided with a guiding surface, and can guide the installation of the flange sleeve on the mold support and can guide the placement of the sand box above the flange sleeve.

[0007] As a preferred solution of the above-mentioned anti-gravity investment casting device suitable for titanium alloy, the bottom surface of the sink is provided with a first sealing groove, the first sealing ring is embedded in the first sealing groove, the middle partition is provided with a second sealing groove, and the second sealing ring is embedded in the second sealing groove.

[0008] As a preferred solution of the above-mentioned anti-gravity investment casting device suitable for titanium alloy, the top surface of the flange structure is provided with a third sealing groove, and a third sealing ring is embedded in the third sealing groove. The third sealing ring can seal the gap between the sand box and the flange structure.

[0009] As a preferred solution of the above-mentioned anti-gravity investment casting device suitable for titanium alloy, the inner diameter of the third sealing ring is smaller than the aperture of the bottom through hole of the sand box.

[0010] As a preferred solution of the above-mentioned anti-gravity investment casting device suitable for titanium alloys, water glass sand is filled between the inner wall of the sand box and the outer wall of the mold shell, and water glass sand is filled between the outer wall of the runner inlet of the mold shell and the inner wall of the bottom through hole of the sand box.

[0011] As a preferred solution of the above-mentioned counter-gravity investment casting device suitable for titanium alloy, the aperture of the bottom through hole of the sand box is 2 to 3 times the aperture of the runner inlet of the mold shell.

[0012] As a preferred solution of the above-mentioned counter-gravity investment casting device suitable for titanium alloy, the hole diameter of the lowermost end of the connecting hole of the flange sleeve is equal to the inner diameter of the middle partition.

[0013] As a preferred solution of the above-mentioned anti-gravity investment casting device suitable for titanium alloys, the lifting structure includes a synchronous motor and a screw transmission structure. The synchronous motor is fixedly arranged on the upper working tank. The input end and the output end of the screw transmission structure are respectively connected to the synchronous motor and the mold support. The synchronous motor drives the mold assembly to move in the vertical direction through the screw transmission structure.

[0014] As a preferred solution of the above-mentioned anti-gravity investment casting device suitable for titanium alloy, the sand box includes a cylindrical box body, an upper cover and a lower plate, the upper cover is connected to the upper end of the cylindrical box body by bolts, and the lower plate is connected to the lower end of the cylindrical box body by bolts.

[0015] The present invention also provides a method for counter-gravity investment casting suitable for titanium alloys, using the above-mentioned counter-gravity investment casting device suitable for titanium alloys, comprising: S1: Connect the mold bracket to the lifting structure, install the flange sleeve on the mold bracket, install the liquid riser on the flange sleeve, and set the liquid riser and the flange sleeve coaxially through the positioning and centering structure; S2: Coaxially set the runner inlet of the mold shell with the sand box through the positioning and centering structure; S3: Fill the sand box with sodium silicate sand to fix the position of the mold shell in the sand box; S4: Perform CO2 blowing hardening operation on the mold shell and sodium silicate sand, and let it stand for a set time; S5: Place the sand box in the preheating furnace to preheat the sand box and the mold shell; S6: Transfer the sand box to the upper working tank, place it above the flange sleeve, and coaxially set the sand box with the flange sleeve through the positioning and centering structure, so that the riser tube is coaxially set with the runner inlet of the mold shell; S7: Place the upper pressure plate above the sand box and connect it to the mold support to fix the position of the sand box; S8: Perform a vacuum pumping operation on the upper working tank and the lower working tank; S9: Heat the riser tube through the riser tube preheating device; S10: Use a water-cooled copper crucible to melt the titanium alloy material; S11: Judge whether the titanium alloy material in the water-cooled copper crucible has been completely melted; If yes, proceed to S12; If not, return to S10; S12: The lifting structure drives the mold assembly to move downward, and the lower end of the riser tube is inserted into the water-cooled copper crucible; S13: Perform a filling operation.

[0016] As a preferred scheme of the above-mentioned counter-gravity investment casting method applicable to titanium alloy, the positioning and centering structure includes a positioning bottom plate, a frustum and a plurality of positioning blocks. The coaxially setting the runner inlet of the mold shell with the sand box in S2 includes: Place the sand box on the positioning bottom plate, and a plurality of positioning blocks are all in contact with the outer wall of the sand box to limit the position of the sand box. At this time, the frustum passes through the bottom through hole of the sand box; Place the mold shell in the sand box, and the frustum passes through the runner inlet of the mold shell to limit the position of the mold shell, so that the runner inlet of the mold shell is coaxially set with the sand box.

[0017] As a preferred scheme of the above-mentioned counter-gravity investment casting method applicable to titanium alloy, the driving of the mold assembly to move downward by the lifting structure in S12 includes: After the bottom surface of the flange sleeve abuts against the middle partition plate, the lifting structure continues to drive the mold support to descend a set distance. At this time, the upper pressure plate, the sand box and the mold support descend together, and the flange sleeve remains stationary, which can squeeze the sealing structure to achieve complete sealing.

[0018] As a preferred solution of the above anti-gravity investment casting method applicable to titanium alloys, filling the water glass sand into the sand box in S3 includes: when the height of the casting is less than the set height, the water glass sand covers the mold shell, and a metal pipe is provided on the mold shell. The metal pipe is communicated with the exhaust hole of the mold shell, and the mold shell exhausts through the metal pipe.

[0019] Compared with the prior art, the beneficial effects of an anti-gravity investment casting device and its casting method applicable to titanium alloys provided by the present invention are as follows: (1) The present invention provides an anti-gravity investment casting device and its casting method applicable to titanium alloys. The anti-gravity investment casting device applicable to titanium alloys is provided with a positioning and centering structure, which can completely align the runner inlet of the mold shell with the riser tube, that is, the runner inlet of the mold shell and the riser tube are coaxially arranged, and the center lines of the runner inlet of the mold shell and the riser tube coincide. Thus, it is avoided that the titanium alloy melt shows a turbulent flow phenomenon at the runner inlet of the mold shell due to misalignment between the riser tube and the runner inlet of the mold shell, resulting in metallurgical defects such as gas entrapment and inclusion in the casting.

[0020] (2) The present invention provides an anti-gravity investment casting device and its casting method applicable to titanium alloys. The anti-gravity investment casting device applicable to titanium alloys is provided with a sealing structure, which can completely seal the lower working tank. When inflating the lower working tank, it is necessary to keep the lower working tank completely sealed so that by increasing the air pressure in the lower working tank, the titanium alloy melt in the water-cooled copper crucible can be pushed to rise along the riser tube. The first sealing ring is located between the flange sleeve and the flange structure to prevent the gas in the lower working tank from escaping along the gaps between the riser tube and the middle partition, between the riser tube and the flange sleeve, between the flange structure and the flange sleeve, and between the flange sleeve and the sand box. The second sealing ring is located between the flange sleeve and the middle partition, which can prevent the gas in the lower working tank from escaping along the gaps between the riser tube and the middle partition and between the middle partition and the flange sleeve, thereby preventing the upper working tank and the lower working tank from having gas cross-flow and causing filling failure when establishing a filling pressure difference by inflating the lower working tank.

[0021] (3) The present invention provides an anti-gravity investment casting device and its casting method applicable to titanium alloys. The anti-gravity investment casting device applicable to titanium alloys uses a water-cooled copper crucible (also called water-cooled copper crucible induction skull melting furnace) to melt titanium alloys. The inner wall of the water-cooled copper crucible is generally 400 - 500 °C, and the molten titanium melt is about 1700 °C. Due to the temperature gradient between the molten titanium melt and the inner wall of the water-cooled copper crucible, a certain thickness of skull is formed on the outer surface of the titanium melt, which can avoid the pollution problem caused to the titanium alloy melt when using other ceramic crucibles to melt titanium alloys, and can greatly guarantee the metallurgical quality of the casting. Description of the Drawings

[0022] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 is a partial structural schematic diagram of an anti-gravity investment casting device applicable to titanium alloy provided by a specific embodiment of the present invention; Figure 2 is Figure 1 an enlarged view of part A in Figure 3 is Figure 1 an enlarged view of part B in Figure 4 is a structural schematic diagram of an anti-gravity investment casting device applicable to titanium alloy provided by a specific embodiment of the present invention; Figure 5 is a partial structural schematic diagram of an alignment structure of an anti-gravity investment casting device applicable to titanium alloy provided by a specific embodiment of the present invention; Figure 6 is an assembly drawing of a mold support, a flange sleeve and a riser tube in an anti-gravity investment casting device applicable to titanium alloy provided by a specific embodiment of the present invention; Figure 7 is an assembly drawing of a mold support, a flange sleeve, a riser tube and a sand box in an anti-gravity investment casting device applicable to titanium alloy provided by a specific embodiment of the present invention; Figure 8 is a structural schematic diagram of a riser tube in an anti-gravity investment casting device applicable to titanium alloy provided by a specific embodiment of the present invention; Figure 9 is a top view of a middle partition plate in an anti-gravity investment casting device applicable to titanium alloy provided by a specific embodiment of the present invention.

[0023] In the figure: 1. Upper working tank; 2. Lower working tank; 3. Mold assembly; 31. Sand box; 32. Mold shell; 33. Flange sleeve; 34. Mold support; 311. Upper cover; 312. Cylindrical box body; 313. Lower plate; 331. Communication hole; 321. Runner inlet; 322. Metal tube; 4. Lifting structure; 5. Riser tube; 51. Flange structure; 6. Water-cooled copper crucible; 7. Middle partition plate; 81. Positioning bottom plate; 82. Circular platform; 83. Positioning stop block; 84. Guide stop block; 841. Guide surface; 91. First sealing ring; 92. Second sealing ring; 10. Third sealing ring; 11. Third sealing groove 12. Liquid-lifting pipe preheating device Detailed implementation mode The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention may be combined with each other. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0024] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected", and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above", and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "below", and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the horizontal height of the first feature is lower than that of the second feature.

[0026] In the description of this embodiment, the orientation or positional relationship such as "above", "below", "right", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and do not have special meanings.

[0027] See Figures 1-9To describe this embodiment, the present invention provides an anti-gravity investment casting device suitable for titanium alloy and its casting method. The anti-gravity investment casting device suitable for titanium alloy includes an upper working tank 1, a mold assembly 3, a lifting structure 4, a lower working tank 2, a water-cooled copper crucible 6, an induction coil, a riser tube 5, a positioning and centering structure, and a sealing structure. A middle partition plate 7 is provided at the bottom of the upper working tank 1. The lower working tank 2 is located below the upper working tank 1 and is connected to the middle partition plate 7. The mold assembly 3 is located in the upper working tank 1. The mold assembly 3 includes an upper pressing plate, a sand box 31, a mold shell 32, a flange sleeve 33, and a mold support 34. The mold shell 32 is located in the sand box 31. The pouring gate inlet 321 of the mold shell 32 penetrates through the bottom through hole at the center of the bottom of the sand box 31. The sand box 31 abuts against the top surface of the flange sleeve 33. The flange sleeve 33 slidably penetrates through the mold support 34. The upper pressing plate abuts against the upper part of the sand box 31. The upper pressing plate is detachably connected to the mold support 34. The bottom surface of the flange sleeve 33 can abut against the middle partition plate 7. The lifting structure 4 is used to drive the mold assembly 3 to move in the vertical direction. Both the water-cooled copper crucible 6 and the induction coil are located in the lower working tank 2. The induction coil is arranged around the water-cooled copper crucible 6. A communication hole 331 is provided at the center of the flange sleeve 33. The riser tube 5 penetrates through the communication hole 331. The riser tube 5 can penetrate through the middle partition plate 7. A flange structure 51 is provided at the upper end of the riser tube 5. The water-cooled copper crucible 6 is located below the riser tube 5. The pouring gate inlet 321 of the mold shell 32 is located above the riser tube 5. The positioning and centering structure is used to make the pouring gate inlet 321 of the mold shell 32 coaxial with the riser tube 5. The sealing structure includes a first sealing ring 91 and a second sealing ring 92. The first sealing ring 91 is located between the flange sleeve 33 and the flange structure 51. The second sealing ring 92 is located between the flange sleeve 33 and the middle partition plate 7.

[0028] In the counter-gravity investment casting device applicable to titanium alloys, the lower working tank 2 serves as the melting chamber. The water-cooled copper crucible 6 in the lower working tank 2 melts the titanium alloy. Before the melting is completed, the lifting structure 4 drives the mold support 34 above the upper working tank 1. First, the riser tube 5 and the mold assembly 3 are installed, and during the installation process, the riser tube 5 and the runner inlet 321 of the mold shell 32 are centered by the positioning and centering structure. After the melting is completed, the lifting structure 4 drives the installed mold assembly 3 to descend. The riser tube 5 passes through the middle partition plate 7 and then enters the water-cooled copper crucible 6. By inflating and pressurizing the lower working tank 2, the continuously increasing air pressure in the lower working tank 2 pushes the titanium alloy melt in the water-cooled copper crucible 6 to rise along the riser tube 5 into the mold shell 32 for the filling operation. When inflating the lower working tank 2, the lower working tank 2 needs to be kept completely sealed to ensure that the increased air pressure in the lower working tank 2 can push the titanium alloy melt in the water-cooled copper crucible 6 to rise along the riser tube 5. The first sealing ring 91 is located between the flange sleeve 33 and the flange structure 51 to prevent the gas in the lower working tank 2 from escaping along the gaps between the riser tube 5 and the middle partition plate 7, between the riser tube 5 and the flange sleeve 33, between the flange structure 51 and the flange sleeve 33, and between the flange sleeve 33 and the sand box 31. The second sealing ring 92 is located between the flange sleeve 33 and the middle partition plate 7, which can prevent the gas in the lower working tank 2 from escaping along the gaps between the riser tube 5 and the middle partition plate 7 and between the middle partition plate 7 and the flange sleeve 33. Thus, the sealing structure can completely seal the lower working tank 2 and prevent gas leakage between the upper working tank 1 and the lower working tank 2 when inflating the lower working tank 2 to establish a filling pressure difference, resulting in filling failure. The positioning and centering structure is used to completely center the runner inlet 321 of the mold shell 32 and the riser tube 5, that is, the runner inlet 321 of the mold shell 32 and the riser tube 5 are coaxially arranged, and the center lines of the runner inlet 321 of the mold shell 32 and the riser tube 5 coincide. This avoids the turbulent flow of the titanium alloy melt at the runner inlet 321 of the mold shell 32 due to misalignment between the riser tube 5 and the runner inlet 321 of the mold shell 32, resulting in metallurgical defects such as gas entrapment and inclusions in the casting. Moreover, the water-cooled copper crucible 6 (also called the water-cooled copper crucible 6 induction skull furnace melting) is used to melt the titanium alloy. The inner wall of the water-cooled copper crucible 6 is generally 400 - 500 °C, and the molten titanium melt is about 1700 °C. Due to the temperature gradient between the molten titanium melt and the inner wall of the water-cooled copper crucible 6, a certain thickness of skull is formed on the outer surface of the titanium melt, which can avoid the pollution problem caused to the titanium alloy melt when using other ceramic crucibles to melt titanium alloys, and can greatly ensure the metallurgical quality of the casting.

[0029] Such as Figures 5-7As shown, optionally, the positioning and centering structure includes a positioning base plate 81, a frustum 82, a plurality of positioning blocks 83, a plurality of guiding blocks 84, and a counterbore provided at the center of the top surface of the flange sleeve 33 and communicating with the communication hole 331. The frustum 82 is detachably arranged on the positioning base plate 81. The plurality of positioning blocks 83 are all fixedly arranged on the positioning base plate 81. The plurality of positioning blocks 83 are arranged at intervals around the frustum 82. When the sand box 31 is placed on the positioning base plate 81, the plurality of positioning blocks 83 are all in contact with the outer wall of the sand box 31. When the mold shell 32 is placed in the sand box 31, the frustum 82 passes through the pouring gate inlet 321 of the mold shell 32, enabling the pouring gate inlet 321 of the mold shell 32 to be coaxially arranged with the sand box 31. The flange structure 51 is embedded in the counterbore, enabling the lifting pipe 5 to be coaxially arranged with the flange sleeve 33. The plurality of guiding blocks 84 are fixedly and spacedly arranged on the mold support 34. When the flange sleeve 33 is placed on the mold support 34 and the sand box 31 is placed on the flange sleeve 33, the plurality of guiding blocks 84 are all in contact with the outer wall of the flange sleeve 33 and are all in contact with the outer wall of the sand box 31, enabling the flange sleeve 33 to be coaxially arranged with the sand box 31.

[0030] By coaxially arranging the pouring gate inlet 321 of the mold shell 32 with the sand box 31, the lifting pipe 5 with the flange sleeve 33, and the flange sleeve 33 with the sand box 31, the positioning purpose of centering the pouring gate inlet 321 of the mold shell 32 with the lifting pipe 5 is achieved, that is, the center line of the pouring gate inlet 321 of the mold shell 32 coincides with the center line of the lifting pipe 5. It can avoid the misalignment of the lifting pipe 5 and the pouring gate inlet 321 of the mold shell 32. Otherwise, it will not only cause the high-temperature titanium alloy melt to scour the mold shell 32, but also cause the titanium alloy melt to have a turbulent flow phenomenon at the pouring gate inlet 321 of the mold shell 32, resulting in metallurgical defects such as gas entrapment and inclusion in the casting.

[0031] The roughness of the outer surface of the die shell 32 is very large. After the die shell 32 is placed in the sand box 31, the bottom surface of the die shell 32 cannot fit with the sand box 31. Therefore, after the die shell 32 is naturally placed in the sand box 31, it is impossible to ensure that the runner inlet 321 of the die shell 32 is centered with the sand box 31, that is, the runner inlet 321 of the die shell 32 coincides with the center line of the sand box 31. In this embodiment, a positioning bottom plate 81, a frustum 82 and a plurality of positioning blocks 83 are used to center the runner inlet 321 of the die shell 32 with the sand box 31. After the sand box 31 is placed on the positioning bottom plate 81, the plurality of positioning blocks 83 are all in contact with the outer wall of the sand box 31, so as to limit the sand box 31, and can also prevent the sand box 31 from shaking and damaging the die shell 32 when it is lifted. It can be understood that the runner inlet 321 of the die shell 32 is a cylindrical structure. Then the die shell 32 is placed in the sand box 31, and the runner inlet 321 of the die shell 32 is sleeved on the frustum 82, which can limit the runner inlet 321 of the die shell 32. It can be understood that the frustum 82 is arranged at the center of the circle formed by the plurality of positioning blocks 83, so that the runner inlet 321 of the die shell 32 is centered with the sand box 31. Among them, the frustum 82 is detachably arranged on the positioning bottom plate 81. As the castings are different, the size of the runner inlet 321 of the die shell 32 will change accordingly. According to the diameter of the runner inlet 321 of the die shell 32, a frustum 82 with a suitable size is selected and installed on the positioning bottom plate 81. Optionally, the diameter of the frustum 82 is 0.5-1 mm smaller than the diameter of the runner inlet 321 of the die shell 32, and the height of the frustum 82 is lower than the height of the runner inlet 321 of the die shell 32.

[0032] The flange structure 51 is embedded in the sunk groove, which can make the lifting pipe 5 and the flange sleeve 33 coaxially arranged. In this embodiment, the outer diameter of the flange structure 51 at the upper end of the lifting pipe 5 is 0.5-1 mm smaller than the inner diameter of the sunk groove of the flange sleeve 33, which can play a role in positioning and centering the lifting pipe 5 and the flange sleeve 33. A plurality of guiding blocks 84 are fixedly and spacedly arranged on the mold support 34. When the flange sleeve 33 is placed on the mold support 34 and the sand box 31 is placed on the flange sleeve 33, the plurality of guiding blocks 84 are all in contact with the outer wall of the flange sleeve 33 and are all in contact with the outer wall of the sand box 31, which can make the flange sleeve 33 and the sand box 31 coaxially arranged. During the test, the flange sleeve 33 is not allowed to deviate, and the flange sleeve 33 needs to be completely positioned and installed. The plurality of guiding blocks 84 are all in contact with the outer wall of the flange sleeve 33, which can play a role in limiting the flange sleeve 33. The plurality of guiding blocks 84 are also all in contact with the outer wall of the sand box 31, which can play a role in limiting the sand box 31, so as to make the flange sleeve 33 and the sand box 31 centered, that is, the center line of the flange sleeve 33 coincides with the center line of the sand box 31. In this embodiment, the outer diameter of the sand box 31 is equal to the outer diameter of the upper end of the flange sleeve 33.

[0033] Optionally, the guiding stop block 84 is provided with a guiding surface 841, which can guide the flange sleeve 33 to be installed on the mold support 34 and can guide the sand box 31 to be placed above the flange sleeve 33. It can be understood that the guiding surface 841 is arranged on the side of the guiding stop block 84 close to the sand box 31.

[0034] As Figures 1-3 shown, optionally, a first sealing groove is provided on the bottom surface of the sunken groove, and a first sealing ring 91 is embedded in the first sealing groove. The middle partition plate 7 is provided with a second sealing groove, and a second sealing ring 92 is embedded in the second sealing groove. The first sealing groove and the second sealing groove respectively limit the positions of the first sealing ring 91 and the second sealing ring 92. After the first sealing ring 91 and the second sealing ring 92 are respectively embedded in the first sealing groove and the second sealing groove, they also exceed the first sealing groove and the second sealing groove by 2-3 mm. Among them, both the first sealing ring 91 and the second sealing ring 92 are graphite sealing rings, and the difference between the outer diameter and the inner diameter is 10-20 mm.

[0035] As Figure 1 、 Figure 2 and Figure 8 shown, optionally, a third sealing groove 11 is provided on the top surface of the flange structure 51, and a third sealing ring 10 is embedded in the third sealing groove 11. The third sealing ring 10 can seal the gap between the sand box 31 and the flange structure 51. The third sealing groove 11 can limit the position of the third sealing ring 10. Since the roughness of the bottom surface of the runner inlet 321 of the mold shell 32 is also very large and cannot be made horizontal, during the liquid-lifting filling stage, when the molten high-temperature titanium alloy melt passes between the liquid-lifting pipe 5 and the runner inlet 321 of the mold shell 32, it may flow towards the gaps on both sides under the action of pressure. The third sealing ring 10 can seal the gap between the sand box 31 and the flange structure 51 to prevent the molten high-temperature titanium alloy melt from passing through. Optionally, the inner diameter of the third sealing ring 10 is smaller than the aperture of the bottom through hole of the sand box 31. It can avoid the molten high-temperature titanium alloy melt from eroding the sand box 31 and even damaging the sand box 31.

[0036] Optionally, the outer diameter of the third sealing groove 11 is smaller than the outer diameter of the flange sleeve 33 to prevent the third sealing ring 10 from warping and deforming when the flange sleeve 33 is pressed down.

[0037] Optionally, water glass sand is filled between the inner wall of the sand box 31 and the outer wall of the mold shell 32, and water glass sand is filled between the outer wall of the runner inlet 321 of the mold shell 32 and the inner wall of the bottom through hole of the sand box 31. The water glass sand not only plays a role in fixing the mold shell 32, but also plays a role in insulating the mold shell 32 and the runner inlet 321 of the mold shell 32, reducing the temperature loss, facilitating the filling of the titanium alloy melt, and greatly improving the yield of the titanium alloy castings produced by counter-gravity casting.

[0038] Optionally, the aperture of the bottom through hole of the sand box 31 is 2 to 3 times the aperture of the runner inlet 321 of the mold shell 32. In order to achieve sequential solidification of the titanium alloy casting, that is, the anti-gravity casting is a top-down solidification sequence, a certain thickness of water glass sand is required at the runner inlet 321 of the mold shell 32 to provide insulation, which can ensure that the runner inlet 321 of the mold shell 32 solidifies last and continuously provides pressure for the casting to compensate for shrinkage, so as to improve the metallurgical quality of the titanium alloy casting.

[0039] The riser 5 has poor impact resistance and is easily damaged. In this embodiment, the diameter of the communication hole 331 gradually increases in the vertical upward direction, which can reduce the collision between the riser 5 and the upper side of the flange sleeve 33 when installing the riser 5, thereby preventing the riser 5 from colliding with the flange sleeve 33. Specifically, the angle α between the inner wall of the communicating hole 331 of the flange sleeve 33 and the bottom surface of the flange sleeve 33 is 10-30°.

[0040] Optionally, the diameter of the lowermost end of the communication hole 331 of the flange sleeve 33 is equal to the inner diameter of the middle partition plate 7. When the flange sleeve 33 is installed, the flange sleeve 33 and the middle partition plate 7 can be completely aligned.

[0041] Optionally, the lifting structure 4 includes a synchronous motor and a screw transmission structure. The synchronous motor is fixedly arranged on the upper working tank 1. The input end and the output end of the screw transmission structure are respectively connected to the synchronous motor and the mold support 34. The synchronous motor drives the mold assembly 3 to move in the vertical direction through the screw transmission structure. Among them, the specific structure of the screw transmission structure belongs to the prior art and will not be repeated here. A flange sleeve 33 is provided in the mold assembly 3 to reduce the length of the screw transmission structure. The length of the screw transmission structure can meet the requirement that the lower end of the flange sleeve 33 abuts against the middle partition 7 and then the mold support 34 is lowered by a set distance.

[0042] Optionally, the sand box 31 includes a cylindrical box body 312, an upper cover 311 and a lower plate 313, wherein the upper cover 311 is connected to the upper end of the cylindrical box body 312 by bolts, and the lower plate 313 is connected to the lower end of the cylindrical box body 312 by bolts. In order to achieve requirements such as sequential solidification and installation, the lower plate 313 of the sand box 31 with a suitable bottom through hole diameter can be replaced according to the size of the runner inlet 321 of the mold shell 32. Considering the adaptability of different castings, the aperture of the bottom through hole on the lower plate 313 of the sand box 31 and the round table 82 in the positioning and centering structure can be determined according to the casting, and the size adjustment is convenient, while greatly reducing the production cost of titanium alloy castings. Optionally, a lifting lug is provided on the upper cover 311.

[0043] The present invention also provides a method for counter-gravity investment casting suitable for titanium alloys, using the above-mentioned counter-gravity investment casting device suitable for titanium alloys, comprising: S1: Connect the mold support 34 to the lifting structure 4. Install the flange sleeve 33 on the mold support 34, and install the lift pipe 5 on the flange sleeve 33. Through the positioning and centering structure, coaxialize the lift pipe 5 with the flange sleeve 33. Specifically, by embedding the flange structure 51 at the upper end of the lift pipe 5 into the sinking groove of the flange sleeve 33, the center line of the flange structure 51 coincides with the center line of the lift pipe 5, and the center line of the sinking groove coincides with the center line of the flange sleeve 33, so that the lift pipe 5 and the flange sleeve 33 are coaxially arranged.

[0044] S2: Through the positioning and centering structure, coaxialize the runner inlet 321 of the mold shell 32 with the sand box 31. Specifically, through the positioning base plate 81, the round platform 82 and multiple positioning blocks 83, the runner inlet 321 of the mold shell 32 can be coaxialized with the sand box 31.

[0045] Specifically, place the sand box 31 on the positioning base plate 81, and multiple positioning blocks 83 are all in contact with the outer wall of the sand box 31 to limit the position of the sand box 31. At this time, the round platform 82 passes through the bottom through hole of the sand box 31; place the mold shell 32 in the sand box 31, and the round platform 82 passes through the runner inlet 321 of the mold shell 32 to limit the position of the mold shell 32, so that the runner inlet 321 of the mold shell 32 and the sand box 31 are coaxially arranged.

[0046] S3: Fill the water glass sand into the sand box 31 to fix the position of the mold shell 32 in the sand box 31. Optionally, when the height of the casting is less than the set height, the water glass sand covers the mold shell 32, and a metal pipe 322 is provided on the mold shell 32, and the metal pipe 322 is communicated with the exhaust hole of the mold shell 32, and the mold shell 32 exhausts through the metal pipe 322. When filling the water glass sand into the sand box 31, it is necessary to cover the exhaust hole of the mold shell 32 to prevent the water glass sand from entering the mold shell 32. The sand used for the water glass sand can be quartz sand or recycled sand, with a particle size of 70 - 140 mesh; the water glass is sodium water glass, the water glass modulus is 2.0 - 2.3 in summer and 2.6 - 2.9 in winter; the density is 1.3 - 1.7 g / cm³; the mass ratio of water glass and quartz sand is about 5% - 8%. After fully mixing the water glass and quartz sand, fill it into the sand box 31, and it should be gradually compacted during filling. The filling height of the water glass sand depends on the height of the casting. When the height of the casting is less than 10 cm and the height of the runner inlet 321 of the mold shell 32 is 2 - 3 cm, the water glass sand needs to completely cover the mold shell 32 to prevent the high-temperature titanium alloy melt from pushing the mold shell 32 at a high filling speed and causing filling failure. At this time, the exhaust hole of the mold shell 32 is surrounded by the metal pipe 322, and the mold shell 32 exhausts through the metal pipe 322; when the height of the casting is greater than 10 cm, the filling height of the water glass sand can be lower than the exhaust hole. At this time, the exhaust hole can be simply covered with aluminum foil, etc., and only a gap needs to be left for exhaust.

[0047] S4: Perform CO2 blowing hardening operation on the mold shell 32 and sodium silicate sand, and let it stand for a set time. After the sodium silicate sand is filled, make blowing channels inside and around the mold shell 32, and then blow CO2 gas. The blowing pressure is 0.1 - 0.3 MPa, the blowing time is 30 - 60 s. After blowing, let it stand for 30 min to allow the CO2 gas to fully diffuse. After performing the CO2 blowing hardening operation and standing, the sodium silicate sand already has a certain strength, which can support the mold shell 32 and keep the position of the mold shell 32 fixed. Moreover, the strength of the mold shell 32 is not high and it is easy to be damaged. By performing the CO2 blowing hardening operation on the mold shell 32 and sodium silicate sand, no external force is applied to the mold shell 32, and the mold shell 32 will not be damaged.

[0048] Since the sodium silicate sand between the mold shell 32 and the sand box 31 has been hardened, the relative position of the mold shell 32 to the sand box 31 no longer changes. Therefore, the sand box 31 is separated from the positioning bottom plate 81, the pouring gate inlet 321 of the mold shell 32 is separated from the frustum 82, and the frustum 82 remains on the positioning bottom plate 81. The relative position of the mold shell 32 to the sand box 31 still does not change. After that, only the sand box 31 and the mold shell 32 are transferred.

[0049] S5: Place the sand box 31 in the preheating furnace to preheat the sand box 31 and the mold shell 32. Specifically, after standing, the sand box 31 is placed in the preheating furnace and dried in the furnace at 200 - 400 °C for 4 h. Subsequently, the furnace temperature is raised to the preheating temperature of the mold shell 32 and then kept warm for 2 h, so that the sand box 31 and the mold shell 32 can reach the preheating temperature.

[0050] S6: Transfer the sand box 31 to the upper working tank 1 and place it above the flange sleeve 33. Through the positioning and centering structure, set the sand box 31 and the flange sleeve 33 coaxially, so that the lifting pipe 5 and the pouring gate inlet 321 of the mold shell 32 are coaxially set. In S1, the lifting pipe 5 and the flange sleeve 33 have been coaxially set. In S2, the pouring gate inlet 321 of the mold shell 32 and the sand box 31 have been coaxially set. Therefore, in S6, by setting the sand box 31 and the flange sleeve 33 coaxially again, the lifting pipe 5 and the pouring gate inlet 321 of the mold shell 32 can be coaxially set.

[0051] S7: Place the upper pressure plate above the sand box 31 and connect it to the mold support 34 to fix the position of the sand box 31. Transfer the preheated sand box 31 to above the flange sleeve 33 through the lifting lug. After that, install the upper pressure plate above the sand box 31 and install and fix the upper pressure plate and the mold support 34 with bolts, and apply a pre-tightening force to the sand box 31 until the upper pressure plate is fully tightened.

[0052] S8: Perform a vacuum pumping operation on the upper working tank 1 and the lower working tank 2. Pump the lower working tank 2 to the required vacuum degree for titanium alloy melting.

[0053] S9: Heat the riser tube 5 through the riser tube preheating device 12. The riser tube preheating device 12 is located in the upper working tank 1. The riser tube preheating device 12 has an open state and a closed state. When it is necessary to heat the riser tube 5, control the riser tube preheating device 12 to be in the closed state. At this time, the riser tube preheating device 12 wraps the riser tube 5 and can heat the riser tube 5. When it is not necessary to heat the riser tube 5, control the riser tube preheating device 12 to be in the open state. At this time, the riser tube 5 is separated from the riser tube preheating device 12.

[0054] S10: The water-cooled copper crucible 6 smelts the titanium alloy material.

[0055] S11: Determine whether the titanium alloy material in the water-cooled copper crucible 6 has completed smelting; If so, proceed to S12; If not, return to S10; S12: The lifting structure 4 drives the mold assembly 3 to move downward, and the lower end of the riser tube 5 is inserted into the water-cooled copper crucible 6. Before the titanium alloy material in the water-cooled copper crucible 6 of the lower working tank 2 melts, the synchronous motor drives the lead screw transmission structure to raise the mold assembly 3 to the highest point. When the titanium alloy material in the water-cooled copper crucible 6 of the lower working tank 2 melts and enters the liquid-risen filling stage, the synchronous motor drives the lead screw transmission structure to lower the mold assembly 3 and the riser tube 5 to the lowest point, and the riser tube 5 is synchronously inserted into the titanium alloy melt in the water-cooled copper crucible 6. At this time, the flange sleeve 33 will press on the middle partition plate 7.

[0056] Optionally, after the bottom surface of the flange sleeve 33 abuts against the middle partition plate 7, the lifting structure 4 continues to drive the mold support 34 to descend a set distance. At this time, the upper pressure plate, the sand box 31 and the mold support 34 descend together, and the flange sleeve 33 remains stationary, which can squeeze the sealing structure to achieve complete sealing. When the flange sleeve 33 presses on the middle partition plate 7, the lifting structure 4 drives the mold assembly 3 and the riser tube 5 to descend a set distance. In this embodiment, the set distance is 5 mm. At this time, the flange sleeve 33 has already abutted against the middle partition plate 7, so the position of the flange sleeve 33 remains unchanged. The upper pressure plate is connected to the mold support 34, and the lifting structure 4 drives the mold support 34 to descend. The mold support 34 slides relative to the flange sleeve 33, so that the upper pressure plate and the sand box 31 descend together with the mold support 34, and will further squeeze the first sealing ring 91, the second sealing ring 92 and the third sealing ring 10 to achieve complete isolation, that is, the sealing is completely in place. The first sealing ring 91 and the second sealing ring 92 can prevent air leakage between the upper working tank 1 and the lower working tank 2 when establishing a filling pressure difference in the lower working tank 2, resulting in filling failure. The third sealing ring 10 can prevent the molten high-temperature titanium alloy melt from passing through the gap between the sand box 31 and the flange structure 51, avoiding erosion of the sand box 31 by the molten high-temperature titanium alloy melt and even damage to the sand box 31.

[0057] S13: Conduct the filling operation. After the filling is completed, the flange sleeve 33 does not need to be removed. Only the riser tube 5 needs to be replaced to carry out the next casting. Moreover, after the sand box 31 is transferred above the flange sleeve 33, the upper pressure plate only needs to be reinstalled to complete the installation of the mold assembly 3. The whole process is convenient to operate, highly efficient, and can achieve a completely sealed state, enabling the filling operation to proceed smoothly.

[0058] Obviously, the embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to only the specific embodiments. According to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. It is not necessary and impossible to enumerate all the embodiments here.

Claims

1. An anti-gravity investment casting device applicable to titanium alloys, characterized in that, Comprising: An upper working tank (1), with a middle partition plate (7) provided at the bottom of the upper working tank (1); A mold assembly (3), the mold assembly (3) is located inside the upper working tank (1), the mold assembly (3) includes an upper pressing plate, a sand box (31), a mold shell (32), a flange sleeve (33) and a mold support (34), the mold shell (32) is located inside the sand box (31), the pouring inlet (321) of the mold shell (32) penetrates through the bottom through hole at the center of the bottom of the sand box (31), the top surface of the sand box (31) abuts against the top surface of the flange sleeve (33), the flange sleeve (33) slidably penetrates through the mold support (34), the upper pressing plate abuts against the upper part of the sand box (31), the upper pressing plate is detachably connected to the mold support (34), and the bottom surface of the flange sleeve (33) can abut against the middle partition plate (7); A lifting structure (4), the lifting structure (4) is used to drive the mold assembly (3) to move in the vertical direction; A lower working tank (2), the lower working tank (2) is located below the upper working tank (1) and is connected to the middle partition plate (7); A water-cooled copper crucible (6) and an induction coil, both the water-cooled copper crucible (6) and the induction coil are located inside the lower working tank (2), and the induction coil is arranged around the water-cooled copper crucible (6); A riser pipe (5), a communication hole (331) is provided at the center of the flange sleeve (33), the riser pipe (5) penetrates through the communication hole (331), a flange structure (51) is provided at the upper end of the riser pipe (5), the riser pipe (5) can penetrate through the middle partition plate (7), the water-cooled copper crucible (6) is located below the riser pipe (5), and the pouring inlet (321) of the mold shell (32) is located above the riser pipe (5); A positioning and centering structure, the positioning and centering structure is used to make the pouring inlet (321) of the mold shell (32) coaxial with the riser pipe (5); A sealing structure, the sealing structure includes a first sealing ring (91) and a second sealing ring (92), the first sealing ring (91) is located between the flange sleeve (33) and the flange structure (51), and the second sealing ring (92) is located between the flange sleeve (33) and the middle partition plate (7).

2. The counter-gravity investment casting device applicable to titanium alloy according to claim 1, wherein: The positioning and centering structure includes a positioning bottom plate (81), a frustum (82), a plurality of positioning blocks (83), a plurality of guiding blocks (84) and a sink provided at the center of the top surface of the flange sleeve (33) and communicating with the communication hole (331). The frustum (82) is detachably arranged on the positioning bottom plate (81), a plurality of positioning blocks (83) are fixedly arranged on the positioning bottom plate (81), the plurality of positioning blocks (83) are arranged at intervals around the frustum (82). When the sand box (31) is placed on the positioning bottom plate (81), the plurality of positioning blocks (83) all abut against the outer wall of the sand box (31). When the mold shell (32) is placed inside the sand box (31), the frustum (82) penetrates through the pouring inlet (321) of the mold shell (32), which can make the pouring inlet (321) of the mold shell (32) coaxial with the sand box (31); The flange structure (51) is embedded in the sink, which can make the riser pipe (5) coaxial with the flange sleeve (33); A plurality of guiding blocks (84) are fixedly and spacedly arranged on the die holder (34). When the flange sleeve (33) is placed on the die holder (34) and the sand box (31) is placed on the flange sleeve (33), the plurality of guiding blocks (84) are all in contact with the outer wall of the flange sleeve (33) and are all in contact with the outer wall of the sand box (31), which can make the flange sleeve (33) and the sand box (31) coaxially arranged.

3. The counter-gravity investment casting device applicable to titanium alloy according to claim 2, wherein: The guiding block (84) is provided with a guiding surface (841), which can guide the flange sleeve (33) to be installed on the die holder (34) and can guide the sand box (31) to be placed above the flange sleeve (33).

4. The counter-gravity investment casting device applicable to titanium alloy according to claim 2, wherein: The bottom surface of the sunken groove is provided with a first sealing groove, the first sealing ring (91) is embedded in the first sealing groove, the middle partition plate (7) is provided with a second sealing groove, and the second sealing ring (92) is embedded in the second sealing groove.

5. The counter-gravity investment casting device applicable to titanium alloy according to claim 1, characterized in that: The top surface of the flange structure (51) is provided with a third sealing groove (11), and a third sealing ring (10) is embedded in the third sealing groove (11). The third sealing ring (10) can seal the gap between the sand box (31) and the flange structure (51).

6. The counter-gravity investment casting device applicable to titanium alloy according to claim 5, wherein: The inner diameter of the third sealing ring (10) is smaller than the aperture of the bottom through hole of the sand box (31).

7. The counter-gravity investment casting device applicable to titanium alloy according to claim 1, characterized in that: Water glass sand is filled between the inner wall of the sand box (31) and the outer wall of the mold shell (32), and water glass sand is filled between the outer wall of the pouring gate inlet (321) of the mold shell (32) and the inner wall of the bottom through hole of the sand box (31).

8. The counter-gravity investment casting device applicable to titanium alloy according to claim 1, characterized in that: The aperture of the bottom through hole of the sand box (31) is 2 to 3 times the aperture of the pouring gate inlet (321) of the mold shell (32).

9. The counter-gravity investment casting device applicable to titanium alloy according to claim 1, characterized in that: The aperture of the lowermost end of the communication hole (331) of the flange sleeve (33) is equal to the inner diameter of the middle partition plate (7).

10. The counter-gravity investment casting device applicable to titanium alloy according to claim 1, characterized in that: The lifting structure (4) includes a synchronous motor and a lead screw drive structure. The synchronous motor is fixedly arranged on the upper working tank (1). The input end and the output end of the lead screw drive structure are respectively in transmission connection with the synchronous motor and the die holder (34). The synchronous motor drives the die assembly (3) to move in the vertical direction through the lead screw drive structure.

11. The counter-gravity investment casting device applicable to titanium alloy according to claim 1, characterized in that: The sand box (31) includes a cylindrical box body (312), an upper cover (311) and a lower plate (313). The upper cover (311) is connected to the upper end of the cylindrical box body (312) by bolts, and the lower plate (313) is connected to the lower end of the cylindrical box body (312) by bolts.

12. An anti-gravity investment casting method applicable to titanium alloys, characterized in that: Using the counter-gravity investment casting device for titanium alloy according to any one of claims 1-11, comprising: S1: Connect the die holder (34) with the lifting structure (4), install the flange sleeve (33) on the die holder (34), install the riser pipe (5) on the flange sleeve (33), and make the riser pipe (5) and the flange sleeve (33) coaxially arranged through the positioning and centering structure; S2: Make the pouring gate inlet (321) of the mold shell (32) and the sand box (31) coaxially arranged through the positioning and centering structure; S3: Fill water glass sand into the sand box (31) to fix the position of the mold shell (32) in the sand box (31); S4: Perform CO2 blowing hardening operation on the mold shell (32) and the water glass sand, and stand for a set time; S5: Place the sand box (31) in the preheating furnace to preheat the sand box (31) and the mold shell (32). S6: Transfer the sand box (31) into the upper working tank (1), place it above the flange sleeve (33), and coaxialize the sand box (31) and the flange sleeve (33) through the positioning and centering structure, so that the lifting pipe (5) and the runner inlet (321) of the mold shell (32) are coaxial. S7: Place the upper pressure plate above the sand box (31) and connect it to the mold support (34) to fix the position of the sand box (31). S8: Perform a vacuum pumping operation on the upper working tank (1) and the lower working tank (2). S9: Heat the lifting pipe (5) through the lifting pipe preheating device (12). S10: The water-cooled copper crucible (6) melts the titanium alloy material. S11: Determine whether the titanium alloy material in the water-cooled copper crucible (6) has been completely melted. If yes, proceed to S12; If no, return to S10; S12: The lifting structure (4) drives the mold assembly (3) to move downward, and the lower end of the lifting pipe (5) is inserted into the water-cooled copper crucible (6). S13: Perform a filling operation.

13. The counter-gravity investment casting method applicable to titanium alloy according to claim 12, wherein: The positioning and centering structure includes a positioning bottom plate (81), a frustum (82) and a plurality of positioning blocks (83). The coaxial setting of the runner inlet (321) of the mold shell (32) and the sand box (31) through the positioning and centering structure in S2 includes: Place the sand box (31) on the positioning bottom plate (81), and all the positioning blocks (83) are in contact with the outer wall of the sand box (31) to limit the position of the sand box (31). At this time, the frustum (82) passes through the bottom through hole of the sand box (31). Place the mold shell (32) in the sand box (31), and the frustum (82) passes through the runner inlet (321) of the mold shell (32) to limit the position of the mold shell (32), so that the runner inlet (321) of the mold shell (32) is coaxial with the sand box (31).

14. The anti-gravity investment casting method applicable to titanium alloy according to claim 12, characterized in that: The driving of the mold assembly (3) downward by the lifting structure (4) in S12 includes: After the bottom surface of the flange sleeve (33) abuts against the middle partition plate (7), the lifting structure (4) continues to drive the mold support (34) to descend a set distance. At this time, the upper pressure plate, the sand box (31) and the mold support (34) descend together, and the flange sleeve (33) remains stationary, and the sealing structure can be squeezed to achieve complete sealing.

15. The anti-gravity investment casting method applicable to titanium alloy according to claim 12, characterized in that: The filling of the sodium silicate sand into the sand box (31) in S3 includes: when the height of the casting is less than the set height, the sodium silicate sand covers the mold shell (32), and a metal pipe (322) is provided on the mold shell (32). The metal pipe (322) is communicated with the exhaust hole of the mold shell (32), and the mold shell (32) exhausts through the metal pipe (322).

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