Self-demolding metal mold for titanium alloy deep cylindrical castings

Abstract

The present invention provides a self-demoulding metal mold for a titanium alloy deep cylindrical casting, belonging to the technical field of titanium alloy casting molds. It includes a water tank, an outer mold cover plate arranged in the water tank, a plurality of outer mold cores fixedly arranged below the outer mold cover plate, and an inner mold cover plate covering the top of the water tank; a plurality of inner mold cores are fixedly arranged at the lower part of the inner mold cover plate, and the inner mold cores are inserted into the outer mold cores after passing through the outer mold cover plate; a pouring gate for injecting titanium liquid into the casting cavity through a runner is arranged on the inner mold cover plate; the outer mold cover plate is hermetically connected with the water tank; a plurality of cylinders are fixedly arranged on the water tank, and the cylinders are communicated with the inside of the water tank; piston rods that are in one-to-one cooperation with the cylinders are fixedly arranged on the inner mold cover plate. The present invention uses a steel mold core or a ceramic mold core to replace the traditional graphite mold core, and can complete the automatic demoulding of the core, and can realize the reuse of most mold parts, thereby saving mold costs and improving production efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloy casting molds, and particularly relates to a self-demolding metal mold for deep cylindrical titanium alloy castings. Background Art

[0002] Titanium alloy has excellent properties such as high strength, strong corrosion resistance, low density, and good heat resistance, which makes titanium alloy castings widely used in the fields of aviation, aerospace, shipbuilding, metallurgy, and chemical industry. However, titanium alloy is prone to react with air at high temperatures, so titanium alloy casting needs to be carried out in a vacuum environment. Currently, the entire process of titanium ingot melting and casting is mostly completed in a closed vacuum space, and the casting difficulty is high.

[0003] Titanium alloy will also react with most refractory materials at high temperatures. Only metal molds, graphite molds, investment shells, and some ceramic materials can be used as titanium alloy mold materials. Currently, most single-piece, small-batch, and large and complex titanium alloy castings are produced by the graphite mold process, which uses artificial graphite to make the mold. However, graphite is brittle and is extremely prone to damage during pouring and transportation. Moreover, when casting deep cylindrical castings, the inner core of the graphite mold cannot be recycled, and the common treatment method is to destructively remove the inner core, resulting in a very large consumption of molds during mass production.

[0004] Metal molds are considered to be one of the most potential processes in the production of titanium alloy castings due to their characteristics such as little processing pollution, multiple reuse, high production efficiency, and low cost of castings during mass production. However, when using metal molds to cast deep cylindrical castings, the metal inner core will be held tightly by the castings after cooling and solidification, making it difficult to pull out the metal inner core and causing difficulties in demolding. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a self-demolding metal mold for deep cylindrical titanium alloy castings in view of the deficiencies of the prior art.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is:

[0007] A self-demolding metal mold for deep cylindrical titanium alloy castings includes a water tank, an outer mold cover plate disposed in the water tank, a plurality of outer mold cores fixedly disposed below the outer mold cover plate, and an inner mold cover plate covering the top of the water tank;

[0008] A plurality of inner mold cores are fixedly disposed at the lower part of the inner mold cover plate. The inner mold cores are inserted into the outer mold cores after passing through the third mold core openings on the outer mold cover plate, and a casting cavity is formed between the inner mold cores and the outer mold cores; a pouring gate for injecting titanium liquid into the casting cavity through a runner is disposed on the inner mold cover plate;

[0009] The outer mold cover plate is hermetically connected to the water tank; a plurality of cylinders are fixedly arranged on the water tank, and the cylinders communicate with the interior of the water tank; a piston rod that is in one-to-one cooperation with the cylinders is fixedly arranged on the inner mold cover plate.

[0010] Furthermore, a graphite runner plate is also arranged between the outer mold cover plate and the inner mold cover plate. A first mold core opening is arranged at a position corresponding to the inner mold core on the graphite runner plate. A plurality of runners are arranged in a groove above the graphite runner plate. The runners are arranged in one-to-one correspondence with the first mold core openings, with one end connected to the first mold core opening and the other end located below the gate.

[0011] Furthermore, a second mold core opening is arranged at a position corresponding to the gate on the graphite runner plate. A detachable graphite mold core is arranged in the second mold core opening. The size of the graphite mold core is the same as that of the inner mold core; an outer mold core is arranged at a position corresponding to the graphite mold core below the outer mold cover plate, and a third mold core opening is arranged at a position corresponding to the graphite mold core on the outer mold cover plate.

[0012] Furthermore, the outer mold cover plate is in clearance fit with the water tank. The outer mold cover plate is provided with a connecting plate extending upward along the four peripheries. The graphite runner plate is clamped in the frame formed by the connecting plates; the connecting plates are fixedly connected to the water tank by fastening bolts.

[0013] Furthermore, a gasket or a sealing ring is arranged between the outer mold cover plate and the water tank.

[0014] Furthermore, a baffle is fixedly arranged on the inner mold cover plate along the outer wall of the water tank. A long hole extending in the vertical direction is arranged on the baffle. The position of the long hole corresponds to the position of the fastening bolt at the baffle, and the nut of the fastening bolt is located in the long hole.

[0015] Furthermore, the length of the long hole is less than the maximum depth of the piston rod inserted into the cylinder.

[0016] Furthermore, both the inner mold core and the graphite mold core are provided with a draft angle of 0.5 degrees.

[0017] Furthermore, the top surface of the connecting plate and the top surface of the graphite runner plate are flush with the top surface of the water tank.

[0018] Furthermore, the gate is located at the center of the inner mold cover plate.

[0019] Furthermore, a water level gauge and a thermometer are arranged on the water tank.

[0020] Furthermore, the inner mold core is a metal core or a ceramic core.

[0021] Due to its excellent comprehensive properties, such as low density, high specific strength, high temperature resistance, and corrosion resistance, titanium alloy has become an indispensable advanced structural material in modern industry. Especially in recent decades, the usage and application level of titanium alloy have been qualitatively improved. However, with the continuous innovation and development of aviation and aerospace technologies, the service environment of key components has become increasingly harsh, which poses higher requirements for the casting quality of titanium alloy.

[0022] As a common titanium alloy casting, the commonly used core types in current casting for deep cylindrical castings include graphite cores, ceramic cores, and metal cores.

[0023] Graphite material is the earliest and most stable molding material applied to titanium alloy, and it is also the most common core type in the casting of current deep cylindrical castings. The most widely used molding method for graphite cores is machining graphite molds. Graphite itself has a low hardness and is easy to process. Not only is the preparation of graphite cores easy, but also in the core removal (demolding) of deep cylindrical castings, the core can be directly damaged for removal, which has significant advantages in terms of the convenience of core removal.

[0024] The common molding method for ceramic cores is hot pressing forming. Although the surface forming quality of ceramic cores is relatively high, the preparation of ceramic cores is difficult, the cost of making molds is high, and for deep cylindrical castings, the shrinkage after solidification and cooling is relatively large, while the shrinkage rate of the ceramic core itself is small. After the casting solidifies, it will hold the ceramic core tightly, making demolding difficult. The commonly used method is still to use destructive core removal means, but due to the significant increase in strength and hardness after high-temperature sintering of ceramics, the difficulty of destruction and cleaning is higher than that of graphite cores.

[0025] Common materials for metal cores include cast iron, cast steel, cast copper, etc. Its main characteristics are that it can be formed by machining combined with welding and can be reused. However, when casting deep cylindrical castings with metal cores, the same situation of difficult demolding after the casting cools occurs, and the metal core cannot be demolded by destruction like graphite cores or ceramic cores. At the same time, the temperature of titanium liquid is up to more than 1700 degrees Celsius, and the metal core often suffers from overburn damage during use.

[0026] For the mass casting of deep cylindrical castings, a mold that can solve the problem of difficult demolding and has a relatively low cost needs to be found. Through the comparison of the three core types, it can be found that under normal circumstances, graphite cores and ceramic cores must be destructively demolded and cannot be reused, so the cost of the mold is high, which also affects the production cost and production efficiency during mass production. Although metal cores can be reused multiple times, the problems of difficult demolding and easy overheating damage during the casting of deep cylindrical castings must be solved.

[0027] Regarding the problem of demolding a metal core, in the prior art, there is a method of chemically corroding the metal core to complete demolding. However, this method has a long demolding time, is not suitable for mass production, and also has environmental pollution problems. Moreover, since the casting surface will be contaminated by long-term immersion in the corrosive liquid, the surface quality of the metal core will also be damaged after multiple chemical corrosions, affecting the reuse of the metal core. In the prior art, there has also appeared a soluble metal core applicable to titanium-aluminum alloy. This core is prepared from a low-melting-point metal or its alloy. When the molten metal fills the mold, it solidifies on the surface of the core. When it has a certain supporting strength, the low-melting-point core softens or even liquefies and flows out, solving the problem of the lack of collapsibility of the metal core. However, this type of metal core cannot be reused and is still not suitable for mass production. Therefore, the prior art has not solved the problem of difficult demolding during mass production of metal cores.

[0028] The reason why the mold core of a deep cylindrical casting is difficult to demold is that the titanium liquid shrinks and clamps the mold core after solidification and cooling. The applicant considered that when the titanium liquid has just solidified, since it has not completely cooled, its shrinkage rate is still relatively small. At this time, the mold core can be withdrawn without affecting the forming quality of the casting. However, titanium alloy is prone to react with air at high temperatures, and titanium alloy casting needs to be carried out in a vacuum environment. Currently, the entire process of melting and casting titanium ingots is mostly completed in a closed furnace body. On the one hand, it is impossible to directly observe the casting situation of the casting in the furnace body and grasp the timing of withdrawing the mold core. On the other hand, it is relatively difficult to complete the action of withdrawing the mold core in a closed space.

[0029] In view of the above situation, the applicant proposes a mold that can self-demold, which can utilize the high temperature of the titanium liquid to generate steam pressure and use the steam pressure to automatically withdraw the mold core at the moment when the casting is solidified. In this case, the mold core can also be made of a ceramic core to achieve the reuse of the ceramic core; at the same time, since the steam pressure is generated by water, the evaporation of water during this period can accelerate the cooling time of the titanium liquid, and water cooling can also protect the mold. In addition, withdrawing the mold core in advance reduces the contact time between the mold core and the casting. Therefore, the mold will not have an overheating situation, making it an ideal choice to use a low-cost metal mold and also greatly increasing the reuse times of the metal mold.

[0030] However, it is difficult to grasp the best timing for self-demolding. It must be at the moment when the titanium liquid has just solidified, that is, at the completion of solidification, when the casting has not completely locked the mold core. If the demolding is too early, since the titanium liquid has not completely solidified, it will affect the quality of the casting; if the demolding is too late, the casting has already locked the mold core, making demolding difficult. Moreover, due to different casting conditions each time, under the influence of factors such as mold temperature and titanium liquid temperature, the moment when the titanium liquid solidifies will also be different. For traditional timed mechanical demolding or manual control demolding methods, it is impossible to accurately grasp the timing of self-demolding. For the steam self-demolding adopted in this application, taking advantage of the fact that the boiling point of water is constant at the same geographical location, it is possible to control the temperature of the boiling steam pressure of water by artificially controlling the amount of water, thereby controlling the temperature of the casting, achieving solidification control, and finally achieving demolding control. Therefore, the present invention can accurately grasp the demolding timing and complete self-demolding.

[0031] The present invention adopts a new mold core structure, introducing a steel mold core or a ceramic mold core to replace the traditional graphite mold. First of all, the present invention adopts a self-demolding structure, which can realize the automatic demolding of the core. Even when using a steel mold, it is not necessary to use chemical corrosion demolding as in the traditional method, and even when using a ceramic mold, it is not necessary to perform destructive demolding. Therefore, the self-demolding structure can ensure the integrity of the steel core or ceramic core, can realize the reuse of most mold parts, and can also greatly reduce the usage amount of graphite molds, thus saving the cost of molds and reducing the processing workload related to graphite molds. Secondly, both steel molds and ceramic molds have high wear resistance and high temperature resistance, can be better reused, can improve the service life of the mold, and thus improve the overall production efficiency. The present invention is simple and practical. There are nine outer mold cores in the mold, and nine deep cylindrical castings can be cast at one time, with higher production efficiency.

[0032] The outer mold cover plate of the present invention is hermetically connected to the water tank, forming a closed space inside the water tank. At the same time, a cylinder is fixedly arranged on the outside of the water tank, and the cylinder is communicated with the inside of the water tank. A piston rod cooperating with the cylinder is also fixedly arranged on the inner mold cover plate. When casting in the present invention, the titanium liquid in the outer mold core exchanges heat with the water in the water tank, which can cause the water to boil into steam. Since the water tank is closed, the steam pressure will push the piston rod to move through the cylinder, and finally push the inner mold cover plate to move upward. Since the titanium liquid has just solidified at this time, the steam pressure can drive the inner mold cover plate to pull out the inner mold core from the outer mold core, thus realizing self-demolding.

[0033] The outer mold cover plate of the present invention is provided with upwardly extending connecting plates along the four edges, and the four connecting plates are connected to form a frame. Each connecting plate is provided with a plurality of fastening screw holes, and bolt through holes are provided on the side walls of the water tank at positions corresponding to these fastening screw holes. The fastening bolts are connected with the fastening screw holes after passing through the bolt through holes, thereby achieving fastening between the connecting plate and the water tank. At the same time, the outer mold cover plate and the water tank have a clearance fit and the fitting clearance is close to zero, or the outer mold cover plate and the water tank have a clearance fit and a sealing gasket or sealing ring is provided between the two, so that the outer mold cover plate and the water tank have good sealing performance. The inner mold cover plate of the present invention is fixedly provided with baffles on both the front and rear sides, and the baffles are tightly attached to the front and rear side walls of the water tank. A plurality of long strip holes are provided on the baffle in the vertical direction, and the long strip holes are all provided at the bolt through holes, and the width of the long strip hole is greater than the width of the fastening bolt nut, and the length is less than the maximum depth of the piston rod inserted into the cylinder, and the top is located between the bolt through hole and the inner mold cover plate. Therefore, the fastening bolts can complete the fastening of the water tank and the connecting plate in the long hole. At the same time, when the inner mold cover plate is driven upward by steam pressure, the piston rod will not be completely disengaged from the cylinder due to the obstruction of the fastening bolts and nuts in the long hole, thereby avoiding steam discharge into the vacuum environment of titanium alloy casting and affecting the quality of the casting.

[0034] The water tank of the present invention is provided with graduated lines or a water level gauge to ensure that the water in the water tank is added in a fixed amount and that the vapor pressure generated by the evaporation of water as the titanium liquid solidifies can achieve self-demolding. The water tank of the present invention can also be provided with a thermometer, a pressure gauge, and a safety valve. The thermometer can measure the temperature of the water and the mold, the pressure gauge can measure the steam pressure inside the water tank, and the safety valve can automatically discharge excessively high pressure gas inside the water tank to avoid accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be described in further detail below with reference to the accompanying drawings.

[0036] Figure 1 : A schematic structural diagram of the present invention;

[0037] Figure 2 : Assembly diagram of the present invention;

[0038] Figure 3 : A schematic structural diagram of the inner mold cover plate of the present invention;

[0039] Figure 4 : A schematic structural diagram of a graphite runner plate and a graphite mold core of the present invention;

[0040] Figure 5 : A schematic structural diagram of the outer mold cover and outer mold core of the present invention;

[0041] Figure 6 : A partial cross-sectional view of the present invention;

[0042] Wherein: 1 - water tank, 11 - cylinder, 12 - bolt through-hole, 2 - inner mold cover plate, 21 - inner mold core, 22 - piston rod, 23 - gate, 24 - baffle, 25 - long hole, 3 - graphite runner plate, 31 - first mold core opening, 32 - runner, 33 - second mold core opening, 34 - clamping groove, 4 - graphite mold core, 41 - clamping block, 5 - outer mold cover plate, 51 - third mold core opening, 52 - connecting plate, 53 - fastening bolt, 54 - fastening screw hole, 6 - outer mold core. Detailed implementation manner

[0043] To better understand the present invention, the content of the present invention will be further clearly described below in conjunction with embodiments and drawings. However, the protected content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0044] Refer to Figures 1-6 , the purpose of this embodiment is to provide a self-demolding metal mold for titanium alloy deep cylindrical castings, including a water tank 1, an inner mold cover plate 2, a graphite runner plate 3, a graphite mold core 4, an outer mold cover plate 5 and an outer mold core 6.

[0045] As Figure 1 , Figure 2 shown, the water tank 1 is a horizontally arranged square box, and the inner mold cover plate 2 is horizontally covered on the top of the water tank 1 as the cover of the water tank 1.

[0046] As Figure 3 shown, the inner mold cover plate 2 is square as a whole, and a gate 23 that penetrates up and down is arranged at the central position. A plurality of inner mold cores 21 are arranged around the gate 23. The inner mold cores 21 are all cylindrical, arranged below the inner mold cover plate 2, and the central axis is vertical.

[0047] As Figure 4 shown, the graphite runner plate 3 is horizontally arranged directly below the inner mold cover plate 2. A second mold core opening 33 that penetrates up and down is arranged at the position corresponding to the gate 23 on the graphite runner plate 3; a plurality of first mold core openings 31 that penetrate up and down are arranged one-to-one at the positions coaxial with the inner mold cores 21 on the graphite runner plate 3. The inner diameter of the first mold core opening 31 is slightly larger than the outer diameter of the inner mold core 21, so that there is a gap for titanium liquid to flow between the first mold core opening 31 and the inner mold core 21. A runner 32 is arranged between each second mold core opening 33 and each first mold core opening 31. The runner 32 is grooved on the upper surface of the graphite runner plate 3 for titanium liquid to flow through.

[0048] Meanwhile, a detachable graphite mold core 4 is coaxially arranged in the second mold core opening 33. The diameter of the graphite mold core 4 is the same as that of the inner mold core 21, and the inner diameter of the second mold core opening 33 is the same as that of the first mold core opening 31. Therefore, there is a gap for the titanium liquid to flow through between the graphite mold core 4 and the second mold core opening 33. The graphite mold core 4 and the graphite runner plate 3 are of a split structure, and a plurality of protruding clamping blocks 41 are arranged along the circumference at the top of the graphite mold core 4. A plurality of clamping grooves 34 arranged in one-to-one correspondence with the clamping blocks 41 are arranged along the circumference at the top of the second mold core opening 33. The clamping blocks 41 can be inserted into the clamping grooves 34 so that the graphite mold core 4 will not easily fall off the graphite runner plate 3, and can also ensure the coaxial state of the graphite mold core 4 and the second mold core opening 33.

[0049] In a possible implementation manner, there are 8 first mold core openings 31, which are respectively distributed at the four vertices and the midpoints of the four sides of a square.

[0050] As Figure 5 shown, the outer mold cover plate 5 is horizontally arranged directly below the graphite runner plate 3. The outer mold cover plate 5 is a square plate-like structure, horizontally arranged, and its size matches the internal size of the water tank 1. Third mold core openings 51 that penetrate up and down are arranged at positions on the outer mold cover plate 5 that are coaxial with the second mold core opening 33 and the first mold core opening 31. The inner diameter of the third mold core opening 51 is the same as that of the first mold core opening 31. An outer mold core 6 is coaxially arranged with the third mold core opening 51 in a one-to-one correspondence. The outer mold core 6 is a hollow cylindrical structure, having a bottom but no cover, and the top is fixedly connected to the outer mold cover plate 5 by means of flange connection.

[0051] In the present invention, the outer mold cover plate 5 and the water tank 1 are hermetically connected to prevent steam from escaping from the gap between the outer mold cover plate 5 and the water tank 1. Specifically, connecting plates 52 extending upward are arranged along the four peripheral edges of the outer mold cover plate 5, and the four connecting plates 52 are connected into a frame. A plurality of fastening screw holes 54 are arranged on each connecting plate 52. Bolt through holes 12 are arranged at positions on the side wall of the water tank 1 corresponding to these fastening screw holes 54. After the fastening bolts 53 pass through the bolt through holes 12, they are connected to the fastening screw holes 54 to realize the fastening between the connecting plates 52 and the water tank 1. At the same time, the outer mold cover plate 5 and the water tank 1 are in clearance fit and the fit clearance is close to zero, so that the outer mold cover plate 5 and the water tank 1 have good sealing performance.

[0052] In a possible implementation manner, the outer mold cover plate 5 and the water tank 1 are in clearance fit, and a gasket or sealing ring is arranged between them, so that the outer mold cover plate 5 and the water tank 1 have good sealing performance.

[0053] In a possible implementation manner, grooves for avoiding the fastening screw holes 54 are arranged at positions on the graphite runner plate 3 corresponding to the fastening screw holes 54 to prevent damage to the graphite runner plate 3 when the fastening screw holes 54 are too long.

[0054] After the outer mold cover plate 5 and the water tank 1 are assembled, the top surface of the connecting plate 52 is flush with the top surface of the water tank 1. At the same time, the size of the square space surrounded by the four connecting plates 52 is the same as the size of the graphite runner plate 3, so that the graphite runner plate 3 can be clamped between the connecting plates 52 and cannot move, and after assembly, the top surface of the graphite runner plate 3 is flush with the top surface of the side wall of the water tank 1. After the inner mold cover plate 2 is assembled, the bottom surface of the inner mold cover plate 2 will fit on the top surface of the water tank 1, the top surface of the connecting plate 52 and the top surface of the graphite runner plate 3.

[0055] After the inner mold core 21 and the graphite mold core 4 are fitted with the outer mold core 6, a cylindrical casting cavity is formed. During casting, the titanium liquid flows in from the gate 23 and is injected into the outer mold core 6 through the runner 32. After the titanium liquid solidifies, it forms a deep cylindrical casting. To realize the automatic extraction of the inner mold core 21, the present invention also fixedly arranges a plurality of cylinders 11 on both the left and right sides of the water tank 1, and the lower part of the cylinder 11 is communicated with the inside of the water tank 1. At the same time, at the coaxial position of the lower parts on both the left and right sides of the inner mold cover plate 2, piston rods 22 are fixedly arranged. The piston rods 22 are in clearance fit with the cylinders 11 and the clearance is close to zero, or there is a sealing ring arranged in the clearance between the two to prevent steam from escaping between the cylinder 11 and the piston rod 22.

[0056] On both the front and rear sides of the inner mold cover plate 2, baffles 24 are fixedly arranged. The baffles 24 are closely attached to the front and rear side walls of the water tank 1. At the same time, a plurality of long strip holes 25 are arranged vertically on the baffles 24. The long strip holes 25 are all arranged at the bolt through holes 12. The width of the long strip holes 25 is greater than the width of the nut of the fastening bolt 53, the length is less than the maximum depth of the piston rod 22 inserted into the cylinder 11, and the top is located between the bolt through hole 12 and the inner mold cover plate 2. Therefore, the fastening bolt 53 can complete the fastening of the water tank 1 and the connecting plate 52 in the long strip holes 25. At the same time, when the inner mold cover plate 2 moves upward under the drive of the steam pressure, blocked by the nut of the fastening bolt 53 in the long strip holes 25, the piston rod 22 will not completely come out of the cylinder 11, so that the water vapor can be sealed in the water tank 1, avoiding the water vapor from being discharged into the vacuum casting environment of the titanium alloy through the cylinder 11 and affecting the casting quality.

[0057] When the present invention is working, a certain amount of water is filled in the water tank 1. After the outer mold core 6 and the outer mold cover plate 5 are assembled, the water surface submerges the lower part of the outer mold core 6 but does not exceed the bottom of the cylinder 11 to prevent water from flowing into the cylinder 11. After pouring the titanium liquid, the water in the water tank 1 exchanges heat with the titanium liquid in the outer mold core 6, and the water will heat up and boil to generate steam. The steam pressure pushes the piston rod 22 to move upward through the cylinder 11, and finally drives the inner mold cover plate 2 to move upward as a whole, realizing the automatic extraction of the inner mold core 21. At the same time, the bottom of the outer mold core 6 does not contact the bottom of the water tank 1, avoiding the loss of heat of the titanium liquid through the water tank 1 and affecting the accurate control of the steam pressure.

[0058] The water injected into the water tank 1 needs to be quantified to ensure that the steam pressure can extract the inner mold core 21 when the titanium liquid just solidifies, and the water should not evaporate in advance to avoid extracting the inner mold core 21 when the titanium liquid has not solidified. Therefore, in a possible implementation, scale lines are provided in the water tank 1 to facilitate obtaining the accurate water filling volume.

[0059] In another possible implementation, one or more of a water level gauge, a thermometer, and a pressure gauge are provided on the water tank 1. The thermometer can obtain the water temperature and the mold temperature to calculate and determine the accurate water filling volume; the water level gauge can obtain the water volume to ensure that the water volume meets the requirements; the pressure gauge can obtain the internal steam pressure of the water tank 1.

[0060] In another possible implementation, a safety valve is also provided on the water tank 1. When the internal pressure of the water tank 1 is too high and exceeds the threshold value, the safety valve can automatically discharge the high-pressure gas to avoid danger.

[0061] In a possible implementation, both the inner mold core 21 and the graphite mold core 4 are provided with a draft angle of 0.5 degrees.

[0062] In the present invention, the water tank 1, the inner mold cover plate 2, the inner mold core 21, the outer mold cover plate 5, and the outer mold core 6 are all made of steel. These steel components can be reused, which can save the mold cost. The inner mold core 21 and the outer mold core 6 can specifically select cast steel as the casting material, and the specific material is 4Cr5MoV1Si die steel.

[0063] In another possible implementation, the inner mold core 21 is made of ceramic material.

[0064] Combined Figures 1-6 The assembly process and the use process of the present invention are introduced:

[0065] First, a quantified amount of water is injected into the water tank 1. Subsequently, the outer mold cover plate 5 with the outer mold core 6 assembled is placed into the water tank 1, and is initially fastened with some fastening bolts 53 (the fastening bolts 53 at the connecting plate 52 are not installed temporarily); next, the graphite runner plate 3 is placed above the outer mold cover plate 5, and then the graphite mold core 4 is placed into the second mold core opening 33; finally, the inner mold cover plate 2 is placed on the water tank 1, and all the fastening bolts 53 are fastened. When the inner mold cover plate 2 is assembled, the inner mold core 21 sequentially passes through the first mold core opening 31 and the third mold core opening 51 and then is inserted into the outer mold core 6.

[0066] During casting, pour the titanium liquid from the pouring gate 23. The titanium liquid will be injected into the outer mold core 6 through the runner 32. After the water in the water tank 1 exchanges heat with the titanium liquid, it boils to generate steam pressure. When the titanium liquid is just solidified, the steam pressure pushes the piston rod 22 upward, and finally drives the inner mold cover plate 2 to move upward to extract the inner mold core 21. When the titanium liquid is completely cooled, disassemble the inner mold cover plate 2 and destroy the graphite runner plate 3 and the graphite mold core 4, then the deep cylindrical titanium alloy casting formed by casting can be obtained.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. A self-demolding metal mold for a titanium alloy deep cylindrical casting, characterized in that: It includes a water tank, an outer mold cover plate arranged inside the water tank, a plurality of outer mold cores fixedly arranged below the outer mold cover plate, and an inner mold cover plate covering the top of the water tank; A plurality of inner mold cores are fixedly arranged at the lower part of the inner mold cover plate. The inner mold cores are inserted into the outer mold cores after passing through the third mold core openings on the outer mold cover plate, and a casting cavity is formed between the inner mold cores and the outer mold cores. A gate for injecting titanium liquid into the casting cavity through a runner is arranged on the inner mold cover plate; The outer mold cover plate is hermetically connected to the water tank. A plurality of cylinders are fixedly arranged on the water tank, and the cylinders are communicated with the inside of the water tank. A piston rod that is in one-to-one cooperation with the cylinders is fixedly arranged on the inner mold cover plate; A graphite runner plate is further arranged between the outer mold cover plate and the inner mold cover plate. First mold core openings are arranged at positions corresponding to the inner mold cores on the graphite runner plate. A plurality of runners are arranged in grooves above the graphite runner plate. The runners are arranged in one-to-one correspondence with the first mold core openings, with one end connected to the first mold core openings and the other end located below the gate.

2. The self-demolding metal mold for titanium alloy deep cylindrical castings according to claim 1, wherein: Second mold core openings are arranged at positions corresponding to the gate on the graphite runner plate. Removable graphite mold cores are arranged in the second mold core openings. The size of the graphite mold cores is the same as that of the inner mold cores. Outer mold cores are arranged at positions corresponding to the graphite mold cores below the outer mold cover plate, and third mold core openings are arranged at positions corresponding to the graphite mold cores on the outer mold cover plate.

3. The self-demolding metal mold for titanium alloy deep cylindrical castings according to claim 2, characterized in that: The outer mold cover plate is in clearance fit with the water tank. Connecting plates extending upward are arranged along the four peripheral edges of the outer mold cover plate. The graphite runner plate is clamped in the frame formed by the connecting plates; the connecting plates are fixedly connected to the water tank by fastening bolts.

4. The self-demolding metal mold for titanium alloy deep cylindrical castings according to claim 3, characterized in that: A gasket or sealing ring is arranged between the outer mold cover plate and the water tank.

5. The self-demolding metal mold for titanium alloy deep cylindrical castings according to claim 4, wherein: A baffle is fixedly arranged on the inner mold cover plate along the outer wall of the water tank. Long strip holes extending in the vertical direction are arranged on the baffle. The positions of the long strip holes correspond to the positions of the fastening bolts at the baffle, and the nuts of the fastening bolts are located in the long strip holes.

6. The self-demolding metal mold for titanium alloy deep cylindrical castings according to claim 5, wherein: The length of the long strip holes is less than the maximum depth of the piston rod inserted into the cylinder.

7. The self-demolding metal mold for titanium alloy deep cylindrical castings according to claim 6, wherein: The top surfaces of the connecting plates and the top surface of the graphite runner plate are flush with the top surface of the water tank.

8. The self-demolding metal mold for titanium alloy deep cylindrical castings according to claim 7, characterized in that: The gate is located at the center of the inner mold cover plate.

9. The self-demolding metal mold for titanium alloy deep cylindrical castings according to claim 8, wherein: Both the inner mold cores and the graphite mold cores are provided with a draft angle of 0.5 degrees.

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