Pressure-regulating mold-filling pressurized solidification device

Abstract

The invention discloses a pressure-regulating mold-filling pressurization solidification device which comprises a pressure tank, a lifting mechanism, an electric furnace, a pneumatic control system, an electric control system and a bracket, wherein the pressure tank is divided into a pressure tank upper tank, a pressure tank lower tank and a middle partition plate; the pressure tank adopts a vertical structure; the pressure-bearing range of the pressure-bearing material is 0.5-2 MPa; the pressure-regulating mold-filling pressurized solidification method using the pressure-regulating mold-filling pressurized solidification device can be applied to processes such as low-pressure casting, counter-pressure casting, pressurized solidification after vacuum-pumping mold-filling, pressurized solidification after vacuum-pumping mold-filling of an upper tank of a pressure tank and the like. According to the method, the alloy mold filling capacity is improved, mold filling of a large-plane thin-wall complex structure is achieved, mold core exhaust is effectively enhanced, and the air hole defect and the chocking problem of a casting are greatly reduced. And the compactness of the alloy structure is improved, the shrinkage porosity defect of the casting is reduced, and the mechanical property of the casting is remarkably improved. And the comprehensive technical effect is excellent.

Description

Technical Field

[0001] The present invention relates to the field of design of pressure regulating filling and pressurized solidification methods, design of special devices and application technologies, and particularly relates to a pressure regulating filling and pressurized solidification device. Background Art

[0002] In the field of casting technology, low-pressure casting, as a common casting method, applies a low pressure to the surface of molten metal, enabling the metal liquid to smoothly fill the mold from bottom to top along the riser tube and solidify under the action of pressure. However, this process has obvious limitations. On the one hand, its production efficiency is low, the equipment cost is high, and there are many restrictions in the production of large castings. On the other hand, due to the relatively complex control of pressure and temperature during the casting process, the deformation of the casting is difficult to accurately predict and control, the alloy microstructure may not be dense enough, and even internal defects such as microcracks may occur, resulting in an increase in the brittleness of the casting.

[0003] In order to overcome the deficiencies of low-pressure casting, differential pressure casting technology has emerged. Based on low-pressure casting, differential pressure casting adds a sealing cover outside the mold and uses the pressure difference to allow liquid metal to crystallize and solidify under a higher pressure, thereby effectively improving the density and mechanical properties of the casting. However, differential pressure casting also faces a series of challenges. The equipment complexity is high, the requirements for high-temperature sealing are extremely strict, and it is difficult to control the size and shape of the casting. Moreover, the properties of the alloy structure are easily affected by defects such as gas holes, shrinkage cavities, and slag inclusions, and the generation of these defects may be due to excessive gas content in the alloy, improper casting process, or poor mold ventilation, etc.

[0004] In addition to the above problems, thin-walled castings also face unique difficulties during the casting process. Due to the thin walls and complex structures of thin-walled castings, the molten metal is significantly affected by surface tension during filling. Surface tension is the result of unbalanced intermolecular forces in the liquid surface layer, which hinders the free flow of the molten metal. Especially when encountering small or complex structures, the molten metal often cannot overcome the resistance of surface tension and is difficult to completely fill the cavity. This problem is particularly prominent in the manufacture of thin-walled castings because the thin-walled structure has higher requirements for the fluidity and filling ability of the molten metal. When the molten metal is hindered by surface tension, it will not only cause incomplete filling of the casting but also trigger a series of defects such as cold shut and misrun, seriously affecting the quality and performance of the casting.

[0005] To solve the filling problem of thin-walled castings, vacuum filling technology is widely used. This technology effectively reduces the influence of surface tension on the filling of molten metal by introducing a vacuum environment during the casting process. Under vacuum conditions, the intermolecular forces on the surface of the molten metal weaken, and the surface tension decreases accordingly, making the molten metal easier to flow and fill the cavity. At the same time, the vacuum environment can also reduce the oxidation and gas entrainment of the molten metal during the filling process, further improving the quality and performance of the casting.

[0006] In summary, the existing casting processes have certain limitations when facing the production of large and complex-structured castings and thin-walled castings. Developing a pressure-regulating filling and pressurized solidification device and its method is of great significance for meeting the requirements of complete forming and quality control of large and complex-structured castings and improving the overall efficiency and product quality of the casting process.

[0007] People urgently hope to obtain a pressure-regulating filling and pressurized solidification device with better technical effects. Summary of the Invention

[0008] The pressure-regulating filling and pressurized solidification device provided by the present invention, in terms of the device structure, the pressure tank adopts a vertical structure, and its sealing surface is uniformly stressed in the vertical direction. With a wedge-shaped locking mechanism, it effectively avoids the problem of local deformation of the sealing ring caused by lateral stress. The selected O-ring fluororubber sealing ring can exhibit better sealing performance in the vertical compression mode, which provides a solid guarantee for the sealing performance of the device. The design of the lifting mechanism relies on an accurate hydraulic and motor drive system. This system can ensure that the canning accuracy of the pressure tank and the middle partition plate reaches an extremely high standard, effectively avoiding the problem of sealing failure caused by inaccurate canning, thereby ensuring the stability and reliability of the operation of the entire device. The design of the pneumatic control system is based on a high-precision digital valve group system, which enables the pneumatic control system to achieve fast and accurate pressure control. During the filling and solidification process of the molten metal, the pneumatic control system can ensure that the pressure always remains stable, providing a good pressure environment for the casting process. The device has two control modes: single-tank control and double-tank control. In the double-tank control mode, the upper and lower tanks (i.e., the upper tank and the lower tank of the pressure tank) each have independent control functions such as pressurization, exhaust, and vacuum pumping. Through the combination of these functions, the device can achieve 4 casting control methods: low-pressure casting, differential-pressure casting, pressurized solidification after vacuum filling of the upper and lower tanks, and pressurized solidification after vacuum filling of the upper tank, greatly expanding the application range of the device and the diversity of the casting process.

[0009] The technical solution of the present invention is as follows:

[0010] The present invention mainly relates to a pressure-regulating filling and pressurized solidification device, and the technical key lies in the scientific design and coordinated operation of each component. The device includes a pressure tank, a lifting mechanism, an electric furnace, a pneumatic control system, an electric control system, and a bracket.

[0011] The pressure tank is divided into the upper pressure tank, the lower pressure tank and the middle partition plate. The pressure tank adopts a vertical structure, and the sealing ring is an O-shaped fluororubber sealing ring, which is equipped with a wedge-shaped locking structure to ensure good airtightness. Based on the pressure range required by the molten metal during the filling and solidification processes, through simulation analysis and experimental verification, its pressure-bearing range is determined to be 0.5 - 2 MPa. This range can not only effectively ensure the filling speed and solidification quality of the molten metal, but also avoid equipment damage caused by excessive pressure or incomplete filling caused by too low pressure. The upper pressure tank, the middle partition plate and the lower pressure tank are arranged in the internal space of the bracket with a frame structure, and the upper pressure tank is installed on the bracket through a lifting mechanism.

[0012] The lifting mechanism has a hoisting unit and a translation unit, and uses a gantry lifting and translation vehicle with a hydraulic system, which includes a hydraulic lifting mechanism and a motor drive mechanism. The use of motor control can achieve accurate positioning of the combined tank. It not only has the functions of hoisting and translating the upper pressure tank, the middle partition plate and the low-pressure gasket, but also the lifting of the upper pressure tank and the middle partition plate adopts hydraulic lifting, and the translation also has multi-stage speed control to achieve accurate positioning of the combined tank, and has multiple protection and anti-falling functions, including synchronization, back pressure, anti-retreat, electrical and other aspects.

[0013] The electric furnace is located in the lower pressure tank. The upper pressure tank and the lower pressure tank are fixedly connected into one body through the middle partition plate. The upper pressure tank is arranged above the middle partition plate, and the middle partition plate is arranged above the lower pressure tank. The three are connected to form a complete pressure vessel. The electric furnace is used to melt the alloy liquid, including a smelting electric furnace, a crucible, a riser pipe, a furnace shell and a sealing groove. The electric furnace is heated by a three-phase power supply, the heating element is a heating resistance belt, the furnace wire is a high-temperature heating belt, and the furnace chamber in the furnace shell is an integrated ceramic fiber furnace chamber. Considering the melting heat and heat conduction characteristics of the molten metal, after experimental verification, the heating power of the electric furnace is set to 50 - 80 kW. This power can heat the molten metal to 1000 - 1500 °C within a reasonable time and maintain the temperature uniformity ≤ ±10 °C, ensuring that the molten metal has good fluidity and filling ability. In addition, the electric furnace for melting aluminum liquid is equipped with a safety operation protection frame to ensure the safety of operators, and at the same time has built-in temperature measurement points, and has the function of measuring the temperature of the alloy melt during the smelting and vacuum casting processes.

[0014] The pneumatic control system is connected to the upper pressure tank and the lower pressure tank in the pressure tank. Its inlet and exhaust pipe orifices are located between the tank body of the pressure tank and the furnace body of the electric furnace. The furnace shell of the electric furnace is separately manufactured from the tank body of the pressure tank. Since the molten metal is sensitive to pressure during the filling process, the pressure control accuracy of the pneumatic control system is designed to be ≤

[0015] ±5 KPa, which can effectively avoid the fluctuation of the molten metal during the filling process and ensure the smoothness of filling and the quality of the casting.

[0016] The electronic control system is respectively connected to the pressure tank, the lifting mechanism, the electric furnace, the pneumatic control system, and the support, and is responsible for the intelligent control and coordination of the operation of the entire device. The upper tank of the pressure tank is hoisted and transported by the lifting mechanism. Before pouring, it is hoisted by the lifting mechanism to directly above the electric furnace and lowered above the sand mold, and the sand mold is placed above the middle partition inside the upper tank of the pressure tank.

[0017] To verify the feasibility and effectiveness of the present invention, the following simulations and experiments were carried out:

[0018] 1. Simulation of the pressure-bearing performance of the pressure tank:

[0019] A three-dimensional model of the pressure tank was established using finite element analysis software, the model was meshed, and high-strength alloy steel was set as the material. A pressure load of 0.5MP - 2MPa was applied to the model to simulate the pressure inside the pressure tank under actual working conditions. At the same time, sealing boundary conditions were set for the contact area between the pressure tank and the sealing components to simulate the actual sealing situation.

[0020] Through simulation analysis, at a pressure of 2MPa, the maximum stress of the pressure tank is concentrated at the connection between the bottom and the side, with a value of 450MPa, which is less than the yield strength of the material of 600MPa, indicating that the structural strength of the pressure tank meets the requirements ( Figure 11 ). The maximum deformation is 0.5mm, mainly concentrated at the top of the pressure tank, and this deformation will not affect the overall structure and sealing performance of the pressure tank ( Figure 12 ).

[0021] 2. Heating performance experiment of the electric furnace:

[0022] The electric furnace was installed in a laboratory with good heat insulation, equipped with a high-precision temperature sensor (accuracy of ±1°C) to measure the temperature of the molten aluminum, and a power adjustment device was used to control the heating power of the electric furnace. At the beginning of the experiment, a certain amount of aluminum ingots were placed in the crucible of the electric furnace, and heating experiments were carried out with heating powers of 50kW, 65kW, and 80kW respectively.

[0023] Heating power (kW) Time required to heat to 1000 °C (min) Temperature uniformity (°C) 50 15 ±8 65 12 ±7 80 10 ±6

[0024] It can be seen from the experimental data that within the heating power range of 50 - 80kW, the electric furnace can heat the molten aluminum to 1000°C within a reasonable time and maintain the temperature uniformity ≤ ±10°C, meeting the melting requirements of the molten metal.

[0025] The pressure regulating, filling, pressurizing and solidifying device described in the present invention preferably claims the following technical content:

[0026] The pressure regulating, filling, pressurizing and solidifying device meets the following requirements:

[0027] The electric furnace is installed inside the lower tank of the pressure tank, flush with the ground; the maximum heating temperature of the electric furnace is 1000 - 1500 °C, the temperature uniformity is ≤ ±10 °C, and the heating power is 50 - 80 kW;

[0028] Temperature measurement points are installed inside the electric furnace, and the surface temperature of the furnace shell is ≤ the ambient temperature + 30 °C;

[0029] The inlet and exhaust pipe ports in the gas control system are located between the tank body and the furnace body, and the furnace body is separated from the tank body.

[0030] The pressure control accuracy of the gas control system during the alloy filling stage is ≤ ±5 KPa, the maximum liquid rising speed during the alloy filling stage is 20 - 200 mm / s in terms of aluminum, the pressure holding and control accuracy is ≤ ±1 KPa, the pressure holding time for the casting to crystallize and solidify is 0 - 60 min, during the solidification pressurization process, the pressure rising speed is ≥ 100 KPa / min, and the deviation between the "pressure difference - time" curve and the set curve is ≤ ±5 KPa.

[0031] Under the condition of the empty furnace in cold state, the internal vacuum degree requirements for the upper tank and the lower tank of the pressure tank are 0.1 Pa - 20 KPa; under working conditions, it can maintain the internal vacuum degree of the upper and lower tanks to reach 0.1 KPa - 50 KPa (absolute vacuum degree), and the vacuum pumping and pressure building time for the inner cavities of the upper tank and the lower tank of the pressure tank is 0.5 - 5 min;

[0032] The pressure regulating, filling, pressurizing and solidifying device adopts a vacuum pump group combined with a rotary vane vacuum pump + vacuum butterfly valve, equipped with a filter, and the ultimate vacuum degree reaches -100 KPa (empty furnace in cold state); for the upper tank of the pressure tank, synchronous gas filling, pressure difference building and exhaust after work all adopt a digital valve group system, ensuring fast synchronous gas filling speed, accurate pressure difference building, and no pollution to the controller circuit during exhaust after work, and is equipped with an exhaust and air supplement system. The pressurizing system adopts a dual - system cooperation for pressure control to achieve speed tracking and accuracy tracking; the pressurizing system for the lower tank of the pressure tank also adopts a digital system for pressure control to achieve speed tracking and accuracy tracking; synchronous gas filling, low - pressure filling and exhaust after work adopt a digital valve group system, equipped with air supplement and exhaust functions, and the pressurizing system adopts a dual - system cooperation for pressure control to achieve speed tracking and accuracy tracking;

[0033] Gas protection is provided. The gas flow of the protection circuit can be digitally set, and the gas flow of other circuits can be manually set. Then they enter the gas mixing system, and the mixed gas is stored in the gas storage tank; at least 4 gas interfaces are provided, and different gases can be designed with different flow rates; the mixed gas has a pressurizing function, and the pressure after pressurization can be set; at least a 2 - cubic gas storage tank for the mixed protection gas is configured; at least a 0.3 - cubic melting protection gas storage tank is configured; the system has dual functions of gas mixing for pouring protection gas and melting protection gas; the pouring protection gas has a self - circulation stirring function after being stored for a certain time to prevent the sedimentation of gas components with high density. There is a monitoring and alarm function for the gas sources used in each circuit and the air pressure in the gas storage tank.

[0034] A cold drying and filtering system is also configured in the pressure regulating, filling and pressurized solidification device, and the cold drying and filtering system adopts three-stage filtering;

[0035] The temperature control accuracy of the electric control system is ±5°C, and it has a timing heating control function, and can automatically turn on heating according to the setting;

[0036] The control part of the electric control system adopts PLC + industrial computer control, and the control part includes a combination of the following functional units: electric furnace working control unit, pressurization control unit, gas control unit, lifting mechanism control unit.

[0037] In the pressure regulating, filling and pressurized solidification device, the control system adopts the IEC standard, selects electrical components and measuring components, and is simple and intuitive to operate. It has a protection and alarm system. Adopt the combined control mode of Siemens PLC + Siemens industrial computer; the locking adopts the hydraulic method, and the opening and closing of the hydraulic valve are controlled by the PLC of the host; the temperature control of the electric furnace adopts the temperature controller + thyristor power regulation + transformer control, the maximum output power is 90kW, and the temperature controller and the upper computer system communicate through the current signal to realize the full record of temperature setting and acquisition; the pressure control system realizes double-layer control of pressure boosting for filling and solidification. The filling process adopts the set process tracking curve control, and the solidification pressure boosting control adopts the independent combined control of the upper and lower tanks. The combined control differential pressure is used to independently control the respective pressure curves of the upper and lower tanks that need to boost pressure after filling.

[0038] The system is set with a full-automatic production mode. When the process is mature, the process parameters can be set and stored to realize the automatic control of different processes for different workpieces; realize the full record of data and the actual production process for product quality control and cause tracing; the system has a shutdown record function, and according to the shutdown time, it prompts the user to do the preparatory work before use, especially baking the furnace and detecting airtightness. The user can use it only after confirming that the preparatory work is done, which greatly ensures the user's use safety.

[0039] The pressure regulating, filling and pressurized solidification device is an aluminum liquid filling, pressurizing and solidifying device, and it has the following 4 groups of feedback signal contact functions: bottom of the mold, intermediate liquid level, top of the mold;

[0040] The bracket includes: a gantry frame, sliding wheels; the bottom sliding wheels are arranged at the bottom of the gantry frame.

[0041] The aforementioned pressure regulating, filling and pressurized solidification device can be used in the pressure regulating, filling and pressurized solidification method. In the process of method application, the technical key is: the pressure regulating, filling and pressurized solidification method can be applied to the low-pressure casting field, and it successively includes the following steps and contents in the process of implementation and application in the low-pressure casting field:

[0042] Step 1, low-pressure filling: The lower tank of the pressure tank intakes air, adjusts the pressure, and the alloy liquid enters the cavity at a set speed and fills the cavity;

[0043] Step 2, shell building and pressure increasing: The lower tank of the pressure tank continues to intake air, and the air pressure is adjusted. According to the set shell building pressure increase and shell building pressure increase time, the shell building and pressure increasing are completed.

[0044] Step 3, crystallization and pressure increasing: The lower tank of the pressure tank continues to intake air, and the air pressure is adjusted. According to the crystallization pressure increase and shell building pressure increase time, until the crystallization and pressure increasing are completed.

[0045] Step 4, pressure holding and solidification: Pressure is held for a set time until the casting solidifies under pressure.

[0046] Step 5, pressure relief: After the pressure holding ends, the lower tank of the pressure tank is depressurized to atmospheric pressure, and the mold is taken out.

[0047] The said pressure regulating filling and pressure applying solidification method is alternatively applied to the differential pressure casting process. Its specific process sequentially includes the following steps and contents:

[0048] Step 1, overall pressure applying: The upper tank and the lower tank of the pressure tank intake air simultaneously and increase pressure synchronously.

[0049] Step 2, filling: Select the mode of the lower tank of the pressure tank intake air or the upper tank of the pressure tank pressure relief, so that a pressure difference is formed between the upper tank and the lower tank of the pressure tank, and the alloy liquid enters the cavity at a set speed and fills the cavity.

[0050] Step 3, shell building and pressure increasing: Select the mode of the lower tank of the pressure tank continuing to intake air or the upper tank of the pressure tank continuing to relieve pressure, adjust the air pressure, and according to the shell building pressure increase and shell building pressure increase time, until the shell building and pressure increasing are completed.

[0051] Step 4, crystallization and pressure increasing: The lower tank of the pressure tank continues to intake air or the upper tank of the pressure tank continues to relieve pressure, adjust the air pressure, and according to the crystallization pressure increase and shell building pressure increase time, until the crystallization and pressure increasing are completed.

[0052] Step 5, pressure holding and solidification: Pressure is held for a set time until the casting solidifies under a higher pressure.

[0053] Step 6, pressure relief: After the pressure holding ends, the upper tank and the lower tank of the pressure tank exhaust air and relieve pressure to atmospheric pressure simultaneously, and the mold is taken out.

[0054] The said pressure regulating filling and pressure applying solidification method is alternatively applied to the process of pressurized solidification after vacuum filling.

[0055] In the process of pressurized solidification after vacuum filling in the upper tank and the lower tank of the pressure tank, the specific process sequentially includes the following steps and contents:

[0056] Step 1, overall vacuum pumping: The upper tank and the lower tank of the pressure tank pump vacuum synchronously.

[0057] Step 2, Overall vacuum filling: The lower tank of the pressure tank intakes air separately, adjusts the vacuum degree, so that a pressure difference is formed between the upper tank and the lower tank of the pressure tank, and the alloy liquid enters the cavity at a set speed and fills the cavity;

[0058] Step 3, Crust formation and pressure increase: The lower tank of the pressure tank intakes air, adjusts the air pressure, and changes according to the crust formation and pressure increase pressure and the crust formation and pressure increase time until the crust formation and pressure increase are completed;

[0059] Step 4, Overall pressure increase: The upper tank and the lower tank of the pressure tank intake air simultaneously, so that the upper tank and the lower tank of the pressure tank increase pressure synchronously to the set pressure;

[0060] Step 5, Crystallization pressure increase: The lower tank of the pressure tank continues to intake air, adjusts the air pressure, and changes according to the crystallization pressure increase pressure and the crust formation and pressure increase time until the crystallization pressure increase is completed;

[0061] Step 6, Pressure holding and solidification: Hold the pressure for a set time until the casting solidifies under a higher pressure;

[0062] Step 7, Pressure relief: After the pressure holding ends, the upper tank and the lower tank of the pressure tank exhaust air and relieve pressure simultaneously to normal pressure, and take out the mold.

[0063] The described pressure regulating filling and pressure increasing solidification method is alternatively applied to the pressure increasing solidification process after vacuum filling of the upper tank of the pressure tank, and its specific process sequentially includes the following steps and contents:

[0064] Step 1, Vacuum filling of the upper tank of the pressure tank: The lower tank of the pressure tank maintains normal pressure, and the upper tank of the pressure tank is separately evacuated to form a pressure difference between the upper tank and the lower tank of the pressure tank. The alloy liquid is sucked into the cavity at a set speed until the alloy fills the mold and the filling is completed;

[0065] Step 2, Crust formation and pressure increase: The upper tank of the pressure tank continues to intake air, adjusts the air pressure, and changes according to the crust formation and pressure increase pressure and the crust formation and pressure increase time to complete the crust formation and pressure increase;

[0066] Step 3, Overall pressure increase: The upper tank and the lower tank of the pressure tank intake air simultaneously, so that the upper tank and the lower tank of the pressure tank increase pressure synchronously to the set pressure;

[0067] Step 4, Crystallization pressure increase: The upper tank of the pressure tank continues to intake air, adjusts the air pressure, and changes according to the crystallization pressure increase pressure and the crust formation and pressure increase time until the crystallization pressure increase is completed;

[0068] Step 5, Pressure holding and solidification: Hold the pressure for a set time until the casting solidifies under a higher pressure;

[0069] Step 6, Pressure relief: After the pressure holding ends, the upper tank and the lower tank of the pressure tank exhaust air and relieve pressure simultaneously to normal pressure, and take out the mold.

[0070] The present invention integrates a pressure tank, a lifting mechanism, an electric furnace, a pneumatic control system, an electric control system, and a bracket. This device supports two control modes: single-tank and double-tank. In the double-tank mode (the upper pressure tank and the lower pressure tank), the upper and lower pressure tanks can independently perform operations such as pressurization, exhaust, and vacuum pumping, and can achieve functions such as synchronous vacuum filling and rapid pressure solidification of the upper and lower pressure tanks, and independent vacuum filling and rapid pressure solidification of the upper tank. The mold and the alloy liquid are respectively placed in the upper and lower pressure tanks. In the initial state, the pressures of the upper and lower pressure tanks are balanced, and both are in a vacuum / negative pressure / atmospheric pressure state. During the casting process of the casting, differential pressure is formed by means of air intake in the lower pressure tank or air extraction in the upper pressure tank according to the process plan, and real-time adjustment is carried out according to the preset process route to ensure smooth filling of the alloy liquid in the cavity. During the solidification stage of the casting, the pressures of the upper and lower pressure tanks will be precisely adjusted according to the process requirements to ensure the smooth solidification of the alloy liquid under pressure. This device and its method significantly improve the filling ability of the alloy, successfully achieve the filling of large-plane thin-wall complex structures, effectively enhance the exhaust of the core, thereby greatly reducing the porosity defects of the casting and solving the problem of backfire. At the same time, the pressure solidification technology further improves the density of the alloy structure, effectively reduces the shrinkage porosity defects of the casting, and significantly improves the mechanical properties of the casting. In addition, this device and method can also meet the process requirements of low-pressure casting, differential-pressure casting, and pressure-regulating casting.

[0071] The beneficial effects of the present invention are reflected in: the alloy is prepared in a controllable environment, reducing the contact between the alloy liquid and the atmosphere, reducing the oxidation inclusions in the alloy, ensuring the purity of the alloy. During the casting process of the casting, the mold and the alloy liquid are respectively placed in the upper and lower pressure tanks, and the environmental pressure in the pressure tank can be adjusted in real time according to the established process route, eliminating the influence of the environmental pressure on the flow of the alloy liquid to the greatest extent, ensuring smooth filling of the alloy liquid in the cavity. During the solidification stage of the casting, the environmental pressure of the upper tank is adjusted in real time according to the process requirements to ensure the solidification of the alloy liquid under pressure, improving the metallurgical quality and density of the casting.

[0072] The innovation of the technical route of the present invention is mainly reflected in the following aspects:

[0073] 1. Double-tank independent control: Compared with traditional low-pressure casting and differential-pressure casting, the present invention adopts a double-tank independent control design, which can independently perform pressurization, exhaust, and vacuum pumping operations on the upper and lower pressure tanks, significantly improving the flexibility and controllability of the filling and solidification processes.

[0074] 2. Combination of Vacuum Filling and Pressure Solidification: The present invention innovatively combines vacuum filling and pressure solidification technologies. By introducing a vacuum environment during the filling stage, the surface tension of the molten metal is reduced, enhancing the filling ability; during the solidification stage, pressure is applied to improve the density and mechanical properties of the casting.

[0075] 3. High-precision Pneumatic Control System: The present invention adopts a high-precision digital valve group system, which can achieve fast and accurate pressure control, ensuring the pressure stability of the molten metal during filling and solidification, and avoiding defects caused by inaccurate pressure control in traditional casting processes. Description of the Drawings

[0076] Figure 1 Schematic diagram of the position of the pressure-regulating filling and pressure-solidifying device in Embodiment 1;

[0077] Figure 2 Front view of the upper tank of the pressure tank;

[0078] Figure 3 Left view of the upper tank of the pressure tank;

[0079] Figure 4 Top view of the upper tank of the pressure tank;

[0080] Figure 5 Stereo reference view of the upper tank of the pressure tank;

[0081] Figure 6 Front view of the middle partition diagram;

[0082] Figure 7 Top view of the middle partition diagram;

[0083] Figure 8 Schematic diagram of the overall structure of the electric furnace;

[0084] Figure 9 Cross-sectional view of the electric furnace;

[0085] Figure 10 Schematic diagram of the lifting mechanism structure;

[0086] Figure 11 Stress distribution diagram of the pressure tank;

[0087] Figure 12 Deformation amount distribution diagram of the pressure tank;

[0088] The meanings of the reference numerals in the drawings are as follows: pressure tank 1, upper tank of the pressure tank 1.1, lower tank of the pressure tank 1.2, middle partition 1.3;

[0089] Lifting mechanism 2, electric furnace 3, melting electric furnace 3.1, crucible 3.2, riser pipe 3.3, furnace shell 3.4, sealing groove 3.5; pneumatic control system 4, electric control system 5, support 6, gantry frame 6.1, sliding wheel 6.2;

[0090] Figure 3 The protruding structures on the left and right sides in the middle are hoisting and positioning structures. Specific implementation manners

[0091] The present invention will be further described below in conjunction with embodiments and the accompanying drawings of the specification, but is not limited thereto.

[0092] Embodiment 1

[0093] A pressure regulating, filling and pressurizing solidifying device, which includes a pressure tank 1, a lifting mechanism 2, an electric furnace 3, a pneumatic control system 4, an electric control system 5, and a bracket 6; wherein: the pressure tank 1 is divided into two parts: an upper pressure tank 1.1, a lower pressure tank 1.2, and a middle partition 1.3; the electric furnace 3 is located in the lower pressure tank 1.2, and the upper pressure tank 1.1 and the lower pressure tank 1.2 are fixedly connected into one body through the middle partition 1.3; the upper pressure tank 1.1 is arranged above the middle partition 1.3; the middle partition 1.3 is arranged above the lower pressure tank 1.2; the upper pressure tank 1.1, the lower pressure tank 1.2, and the middle partition 1.3 are connected into a complete pressure vessel, the sealing ring adopts an O-shaped fluororubber sealing ring, and the locking structure adopts a wedge-shaped lock to ensure airtightness; the structure of the pressure tank 1 adopts a vertical structure; and its pressure bearing range is 0.5 - 2 MPa;

[0094] The upper pressure tank 1.1, the middle partition 1.3, and the lower pressure tank 1.2 are arranged in the internal space of the bracket 6 with a frame structure; the upper pressure tank 1.1 is arranged on the bracket 6 through the lifting mechanism 2; the lifting mechanism 2 has a hoisting unit and a translation unit; the lifting mechanism 2 is a gantry lifting and translating vehicle + hydraulic system; the lifting mechanism 2 includes a hydraulic lifting mechanism or / and a motor driving mechanism, and it can achieve precise positioning of the tank combination by motor control; it has the functions of hoisting and translating the upper pressure tank 1.1, the middle partition 1.3, and the low-pressure gasket; the lifting of the upper pressure tank 1.1 and the middle partition 1.3 adopts hydraulic lifting; the translation has multi-stage speed control to achieve precise positioning of the tank combination; it has multiple protection functions against falling, such as synchronization, back pressure, anti-retreat, and electricity.

[0095] The pneumatic control system 4 is connected to the upper pressure tank 1.1 and the lower pressure tank 1.2 in the pressure tank 1; the electric control system 5 is respectively connected to the pressure tank 1, the lifting mechanism 2, the electric furnace 3, the pneumatic control system 4, and the bracket 6;

[0096] The electric furnace 3 is used to melt alloy liquid. The electric furnace 3 includes: a smelting electric furnace 3.1, a crucible 3.2, a riser pipe 3.3, a furnace shell 3.4, and a sealing groove 3.5; The electric furnace 3 is heated by a three-phase power supply, the heating component is a heating resistance belt, and the furnace wire is selected as a high-temperature heating belt. The furnace chamber inside the furnace shell 3.4 is an integrated ceramic fiber furnace chamber; The electric furnace 3 for melting aluminum liquid has a safety operation protection frame to protect the safety of operators. The electric furnace 3 is internally provided with temperature measurement points and has the function of measuring the temperature of the alloy melt during the smelting and vacuum casting processes. The inlet and exhaust pipe ports of the pneumatic control system 4 are located between the tank body of the pressure tank 1 and the furnace body of the electric furnace 3. The furnace shell 3.4 of the electric furnace 3 is separately manufactured from the tank body of the pressure tank 1;

[0097] The upper tank 1.1 of the pressure tank is hoisted and transported by the lifting mechanism 2. Before pouring, it is hoisted by the lifting mechanism 2 directly above the electric furnace 3 and lowered onto the sand mold; The sand mold is placed above the middle partition 1.3 inside the upper tank 1.1 of the pressure tank.

[0098] The pressure regulating, filling, pressurizing and solidifying device meets the following requirements:

[0099] The electric furnace 3 is installed inside the lower tank 1.2 of the pressure tank and is flush with the ground; The maximum heating temperature of the electric furnace 3 is 1000 - 1500 °C, the temperature uniformity is ≤ ±10 °C, and the heating power is: 50 - 80 kW;

[0100] The electric furnace 3 is internally provided with temperature measurement points, and the surface temperature of the furnace shell is ≤ ambient temperature + 30 °C;

[0101] The inlet and exhaust pipe ports in the pneumatic control system 4 are located between the tank body and the furnace body, and the furnace body is separated from the tank body.

[0102] The pressure control accuracy of the pneumatic control system 4 during the alloy filling stage is ≤ ±5 KPa. The maximum liquid rising speed during the alloy filling stage is 20 - 200 mm / s in terms of aluminum. The pressure holding and control accuracy is ≤ ±1 KPa. The pressure holding time for the casting to crystallize and solidify is: 0 - 60 min. During the solidification pressurization process, the pressure rising speed is ≥ 100 KPa / min, and the deviation between the "pressure difference - time" curve and the set curve is ≤ ±5 KPa.

[0103] Under the condition of an empty furnace in cold state, the internal vacuum degree requirements for the upper tank 1.1 and the lower tank 1.2 of the pressure tank are 0.1 Pa - 20 KPa; Under working conditions, it can maintain the internal vacuum degree of the upper and lower tanks to reach 0.1 KPa - 50 KPa (absolute vacuum degree). The vacuum pumping and pressure building time for the inner cavities of the upper tank 1.1 and the lower tank 1.2 of the pressure tank is 0.5 - 5 min;

[0104] The pressure regulating, mold filling and pressure solidifying device adopts a vacuum pump group combined with a rotary vane vacuum pump + vacuum butterfly valve, is equipped with a filter, and the ultimate vacuum degree reaches -100 KPa (cold state of the empty furnace); for the upper tank 1.1 of the pressure tank, the digital valve group system is used for synchronous gas charging, building differential pressure and exhausting after work, ensuring fast synchronous gas charging speed, accurate building of differential pressure, and no pollution to the controller circuit during exhausting after work. An exhaust and air supplement system is provided. The pressurizing system adopts a dual-system cooperative pressure control to achieve speed tracking and precision tracking; for the lower tank 1.2 of the pressure tank, the pressurizing system also adopts a digital system cooperative pressure control to achieve speed tracking and precision tracking; for synchronous gas charging, low-pressure mold filling and exhausting after work, the digital valve group system is used, and an air supplement and exhaust function is provided. The pressurizing system adopts a dual-system cooperative pressure control to achieve speed tracking and precision tracking.

[0105] Gas protection is provided to ensure that the gas flow of 2 circuits can be digitally set, and the gas flow of other circuits can be manually set. At the same time, they enter the gas mixing system, and the mixed gas is stored in the gas storage tank; at least 4 gas interfaces are provided, and different gases can be designed with different flow rates; the mixed gas has a pressurizing function, and the pressure after pressurization can be set; at least 2 cubic meters of gas storage tank for the mixed protective gas is configured; at least 0.3 cubic meters of melting protective gas storage tank is configured; the system has dual functions of gas mixing for pouring protection gas and gas mixing for melting protection; the pouring protection gas has a self-circulation stirring function after being stored for a certain time to prevent the settlement of gas components with high density. There is a monitoring and alarm function for the gas sources used in each circuit and the air pressure of the gas storage tank.

[0106] A cold drying and filtering system is also configured in the pressure regulating, mold filling and pressure solidifying device, and the cold drying and filtering system adopts three-stage filtering.

[0107] The temperature control accuracy of the electric control system 5 is ±5 °C, and it has a timing heating control function and can automatically turn on heating according to the setting.

[0108] The control part of the electric control system 5 adopts PLC + industrial computer control, and the control part includes a combination of the following functional units: electric furnace working control unit, pressurizing control unit, gas control unit, lifting mechanism control unit.

[0109] In the pressure regulating, mold filling and pressurized solidification device, the control system adopts the IEC standard, selects electrical components and measuring components, and is simple and intuitive to operate. It has a protection and alarm system. It adopts the combined control mode of Siemens PLC + Siemens industrial computer; the locking adopts the hydraulic method, and the opening and closing of the hydraulic valve are controlled by the PLC of the main machine; the temperature control of the electric furnace adopts the temperature controller + thyristor power regulation + transformer control, and the maximum output power is 90kW. The temperature controller and the upper computer system communicate through the current signal to realize the full recording of temperature setting and acquisition; the pressure control system realizes double-layer control of pressure boosting for mold filling and solidification. The mold filling process adopts the set process tracking curve control, and the solidification pressure boosting control adopts the independent combined control of the upper and lower tanks. The differential pressure is jointly controlled, and the respective pressure curves of the upper and lower tanks that need to boost pressure after mold filling are independently controlled;

[0110] The system is set with a full-automatic production mode. When the process is mature, the process parameters can be set and stored to realize the automatic control of different processes for different workpieces; the full recording of data and the actual production process is realized for product quality control and cause tracing; the system has a shutdown recording function, which prompts the user to do the preparatory work before use according to the shutdown time, especially baking the furnace and detecting the airtightness. The system can only be used after the user confirms that the preparatory work is done, which greatly ensures the user's use safety.

[0111] The pressure regulating, mold filling and pressurized solidification device is an aluminum liquid mold filling and pressurized solidification device, which has the following 4 groups of feedback signal contact functions: bottom of the mold, intermediate liquid level, top of the mold;

[0112] The bracket 6 includes: a gantry frame 6.1 and sliding wheels 6.2; the bottom sliding wheels 6.2 are arranged at the bottom of the gantry frame 6.1.

[0113] The pressure regulating, mold filling and pressurized solidification method using the pressure regulating, mold filling and pressurized solidification device can be applied to the field of low-pressure casting. The following steps and contents are included in turn during its implementation in the field of low-pressure casting:

[0114] Step 1, low-pressure mold filling: The lower tank 1.2 of the pressure tank intakes air, adjusts the pressure, and the alloy liquid enters the cavity at a set speed and fills the cavity;

[0115] Step 2, shell-forming pressure boosting: The lower tank 1.2 of the pressure tank continues to intake air, adjusts the air pressure, and changes according to the set shell-forming pressure boosting pressure and shell-forming pressure boosting time to complete the shell-forming pressure boosting;

[0116] Step 3, crystallization pressure boosting: The lower tank 1.2 of the pressure tank continues to intake air, adjusts the air pressure, and changes according to the crystallization pressure boosting pressure and shell-forming pressure boosting time until the crystallization pressure boosting is completed;

[0117] Step 4, pressure holding and solidification: Hold the pressure for a set time until the casting solidifies under pressure;

[0118] Step 5, pressure relief: After the pressure holding is completed, the lower tank 1.2 of the pressure tank is depressurized to atmospheric pressure, and the mold is taken out.

[0119] The pressure regulating, filling and pressurizing solidification method of the pressure regulating, filling and pressurizing solidification device can also be alternatively applied to the differential pressure casting process. The specific process sequentially includes the following steps and contents:

[0120] Step 1, overall pressurization: The upper tank 1.1 and the lower tank 1.2 of the pressure tank are simultaneously filled with gas and pressurized synchronously.

[0121] Step 2, filling: Select the mode of filling the lower tank 1.2 of the pressure tank with gas or relieving the pressure of the upper tank 1.1 of the pressure tank, so that a pressure difference is formed between the upper tank 1.1 and the lower tank 1.2 of the pressure tank, and the alloy liquid enters the cavity at a set speed and fills the cavity.

[0122] Step 3, shell-forming pressurization: Select the mode of continuing to fill the lower tank 1.2 of the pressure tank with gas or continuing to relieve the pressure of the upper tank 1.1 of the pressure tank, adjust the air pressure, and change according to the shell-forming pressurization pressure and the shell-forming pressurization time until the shell-forming pressurization is completed.

[0123] Step 4, crystallization pressurization: The lower tank 1.2 of the pressure tank continues to be filled with gas or the upper tank 1.1 of the pressure tank continues to relieve the pressure, adjust the air pressure, and change according to the crystallization pressurization pressure and the shell-forming pressurization time until the crystallization pressurization is completed.

[0124] Step 5, pressure holding and solidification: Hold the pressure for a set time until the casting solidifies under a higher pressure.

[0125] Step 6, pressure relief: After the pressure holding is completed, the upper tank 1.1 and the lower tank 1.2 of the pressure tank are simultaneously exhausted and depressurized to atmospheric pressure, and the mold is taken out.

[0126] The pressure regulating, filling and pressurizing solidification method of the aforementioned pressure regulating, filling and pressurizing solidification device can also be alternatively applied to the process of pressurizing solidification after vacuum filling.

[0127] In the process of pressurizing solidification after vacuum filling of the upper tank 1.1 and the lower tank 1.2 of the pressure tank, the specific process sequentially includes the following steps and contents:

[0128] Step 1, overall vacuum pumping: The upper tank 1.1 and the lower tank 1.2 of the pressure tank are pumped to vacuum synchronously.

[0129] Step 2, overall vacuum filling: The lower tank 1.2 of the pressure tank is filled with gas alone, and the vacuum degree is adjusted to form a pressure difference between the upper tank 1.1 and the lower tank 1.2 of the pressure tank, and the alloy liquid enters the cavity at a set speed and fills the cavity.

[0130] Step 3, shell-forming pressurization: The lower tank 1.2 of the pressure tank is filled with gas, and the air pressure is adjusted and changed according to the shell-forming pressurization pressure and the shell-forming pressurization time until the shell-forming pressurization is completed.

[0131] Step 4, overall pressurization: The upper tank 1.1 and the lower tank 1.2 of the pressure tank are simultaneously filled with gas, so that the upper tank 1.1 and the lower tank 1.2 of the pressure tank are synchronously pressurized to the set pressure;

[0132] Step 5, crystallization pressurization: The lower tank 1.2 of the pressure tank continues to be filled with gas, and the air pressure is adjusted. It changes according to the crystallization pressurization pressure and the crusting pressurization time until the crystallization pressurization is completed;

[0133] Step 6, pressure holding and solidification: Pressure is held for a set time until the casting solidifies under a higher pressure;

[0134] Step 7, pressure relief: After the pressure holding is completed, the upper tank 1.1 and the lower tank 1.2 of the pressure tank are simultaneously exhausted and depressurized to atmospheric pressure, and the mold is taken out.

[0135] The pressure regulating, filling, pressurizing and solidifying method of the aforementioned pressure regulating, filling, pressurizing and solidifying device can also be alternatively applied to the process of vacuum filling and pressurizing solidification of the upper tank 1.1 of the pressure tank. Its specific process sequentially includes the following steps and contents:

[0136] Step 1, vacuum filling of the upper tank 1.1 of the pressure tank: The lower tank 1.2 of the pressure tank maintains atmospheric pressure, and the upper tank 1.1 of the pressure tank is separately evacuated to form a pressure difference between the upper tank 1.1 and the lower tank 1.2 of the pressure tank. The alloy liquid is sucked into the cavity at a set speed until the alloy fills the mold and the filling is completed;

[0137] Step 2, crusting pressurization: The upper tank 1.1 of the pressure tank continues to be filled with gas, and the air pressure is adjusted. It changes according to the crusting pressurization pressure and the crusting pressurization time to complete the crusting pressurization;

[0138] Step 3, overall pressurization: The upper tank 1.1 and the lower tank 1.2 of the pressure tank are simultaneously filled with gas, so that the upper tank 1.1 and the lower tank 1.2 of the pressure tank are synchronously pressurized to the set pressure;

[0139] Step 4, crystallization pressurization: The upper tank 1.1 of the pressure tank continues to be filled with gas, and the air pressure is adjusted. It changes according to the crystallization pressurization pressure and the crusting time until the crystallization pressurization is completed;

[0140] Step 5, pressure holding and solidification: Pressure is held for a set time until the casting solidifies under a higher pressure;

[0141] Step 6, pressure relief: After the pressure holding is completed, the upper tank 1.1 and the lower tank 1.2 of the pressure tank are simultaneously exhausted and depressurized to atmospheric pressure, and the mold is taken out.

[0142] The low-pressure casting process of a certain aviation-class main engine case casting. The specific process is as follows:

[0143] (1) Low-pressure filling: There is no need for the upper tank 1.1 of the pressure tank; the lower tank 1.2 of the pressure tank intakes air separately, adjusts the pressure of the lower tank 1.2 of the pressure tank, and makes the alloy liquid enter the mold cavity from the melting furnace at a set speed of 75 mm / s until the alloy fills the mold to complete the filling;

[0144] (2) Crust-forming pressurization: The lower tank 1.2 of the pressure tank continues to intake air, adjusts the air pressure separately, sets the crust-forming pressurization pressure to 3 KPa and the crust-forming pressurization time to 30 S to complete the crust-forming pressurization;

[0145] (3) Crystallization pressurization: The lower tank 1.2 of the pressure tank continues to intake air, adjusts the air pressure separately, and the crystallization pressurization pressure is 5 KPa until the crystallization pressurization is completed;

[0146] (4) Pressure holding and solidification: Pressure holding is carried out according to the set time of 600 S until the casting solidifies under pressure;

[0147] (5) Pressure relief: After the pressure holding is over, the lower tank 1.2 of the pressure tank exhausts air to relieve pressure to atmospheric pressure, and the mold is taken out.

[0148] The differential pressure casting process of a certain aluminum alloy shell. The specific process is as follows:

[0149] (1) Overall pressurization: The upper tank 1.1 and the lower tank 1.2 of the pressure tank intake air simultaneously, so that the two tanks of the upper tank 1.1 and the lower tank 1.2 of the pressure tank are synchronously pressurized to 700 KPa. During the pressurization process, it is necessary to ensure that the pressure difference is basically constant (deviation ≤ ±2 KPa) to avoid too large a fluctuation amplitude of the alloy liquid in the riser tube in the furnace;

[0150] (2) Filling: The operator independently selects the air intake mode of the lower tank 1.2 of the pressure tank to make the pressure difference △P between the upper tank 1.1 and the lower tank 1.2 of the pressure tank equal to 30 KPa, and makes the alloy liquid enter the mold cavity from the melting furnace at a set speed of 30 mm / s until the alloy fills the mold to complete the filling. During the filling process, △P between the upper tank 1.1 and the lower tank 1.2 of the pressure tank ≤ ±0.5 KPa;

[0151] (3) Crust-forming pressurization: The lower tank 1.2 of the pressure tank continues to intake air, adjusts the air pressure, makes the pressure difference between the upper tank 1.1 and the lower tank 1.2 of the pressure tank 2 KPa for crust-forming, the crust-forming pressurization time is 10 S, the pressure rising speed during the pressurization process is 1 KPa / s, and the control accuracy of △P between the upper tank 1.1 and the lower tank 1.2 of the pressure tank ≤ ±0.5 KPa until the crust-forming pressurization is completed;

[0152] (4) Crystallization pressurization: The lower tank 1.2 of the pressure tank continues to intake air, adjusts the air pressure, makes the pressure difference between the upper tank 1.1 and the lower tank 1.2 of the pressure tank 15 KPa for crystallization pressurization, the pressure rising speed during the pressurization process is 1 KPa / s, and the control accuracy of △P between the upper tank 1.1 and the lower tank 1.2 of the pressure tank ≤ ±0.5 KPa until the crystallization pressurization is completed;

[0153] (5) Pressure holding and solidification: Hold the pressure for the set time of 540 s until the casting solidifies under a relatively high pressure.

[0154] (6) Pressure relief: After the pressure holding is completed, the upper tank 1.1 and the lower tank 1.2 of the pressure tank exhaust air and relieve pressure simultaneously until the normal pressure is reached. Then open the upper tank 1.1 of the pressure tank and take out the mold.

[0155] The differential pressure casting process of a certain aluminum alloy housing. The high-precision air control system of the present invention can achieve fast and accurate pressure control, ensuring the pressure stability of the molten metal during the filling process. For the castings produced by the present invention, the dimensional accuracy is improved by 15%.

[0156] The process of evacuating, filling, pressurizing and solidifying the upper and lower tanks of a certain thin-walled and complex aluminum alloy casing. The specific process is as follows:

[0157] (1) Overall vacuum pumping: The upper tank 1.1 and the lower tank 1.2 of the pressure tank are evacuated synchronously to reach the working vacuum degree P0 ≤ -80 KPa.

[0158] (2) Overall vacuum filling: The lower tank 1.2 of the pressure tank intakes air alone, adjusts the vacuum degree of the lower tank, so that a pressure difference of 50 KPa is formed between the upper tank 1.1 and the lower tank 1.2 of the pressure tank. The alloy liquid enters the mold cavity from the melting furnace at the set speed of 50 mm / s until the alloy fills the mold and the filling is completed. During the filling process, the pressure difference △P between the upper tank 1.1 and the lower tank 1.2 of the pressure tank is controlled with an accuracy of ≤ ±0.5 KPa.

[0159] (3) Crust forming and pressure boosting: The lower tank 1.2 of the pressure tank intakes air and adjusts the air pressure alone, so that the pressure difference △P between the upper tank 1.1 and the lower tank 1.2 of the pressure tank changes according to the crust forming and pressure boosting pressure of 2 KPa and the crust forming and pressure boosting time of 5 s. During the pressure boosting process, the pressure rising speed is 1 KPa / s, and the control accuracy of the pressure difference △P between the upper tank 1.1 and the lower tank 1.2 of the pressure tank is ≤ ±0.5 KPa until the crust forming and pressure boosting is completed.

[0160] (4) Overall pressure boosting: The upper tank 1.1 and the lower tank 1.2 of the pressure tank intake air simultaneously, so that the two tanks of the upper tank 1.1 and the lower tank 1.2 of the pressure tank are synchronously boosted from negative pressure to above 600 KPa within 70 s. During the pressure boosting process, it is necessary to ensure that the pressure difference is basically constant (deviation ≤ ±2 KPa) to avoid large fluctuations of the alloy liquid up and down in the mold cavity.

[0161] (5) Crystallization pressure boosting: The lower tank 1.2 of the pressure tank continues to intake air and adjusts the air pressure alone, so that the pressure difference △P between the upper tank 1.1 and the lower tank 1.2 of the pressure tank changes according to the crystallization pressure boosting pressure of 5 KPa. During the pressure boosting process, the pressure rising speed is 1 KPa / s, and the control accuracy of the pressure difference △P between the upper tank 1.1 and the lower tank 1.2 of the pressure tank is ≤ ±0.5 KPa until the crystallization pressure boosting is completed.

[0162] (6) Pressure holding and solidification: Hold the pressure for 600 s according to the set time until the casting solidifies under a relatively high pressure.

[0163] (7) Pressure relief: After the pressure holding ends, the upper tank 1.1 and the lower tank 1.2 of the pressure tank exhaust air simultaneously to relieve the pressure to atmospheric pressure, open the upper tank 1.1 of the pressure tank, and take out the mold.

[0164] The casting process of a thin-walled and complex aluminum alloy casing with vacuum filling in the upper and lower tanks and pressure-assisted solidification. Compared with traditional low-pressure casting, the present invention significantly improves the filling efficiency and casting quality through double-tank independent control and vacuum filling technology. The results show that for the castings produced by the present invention, the porosity defects are reduced by 30%, the shrinkage porosity defects are reduced by 25%, and the mechanical properties are improved by 20%.

[0165] The casting process of a thin-walled and complex magnesium alloy casing with vacuum filling in the upper tank and pressure-assisted solidification. The specific process is as follows:

[0166] (1) Vacuum filling in the upper tank: The lower tank 1.2 of the pressure tank maintains atmospheric pressure, and the upper tank is evacuated alone to form a pressure difference between the upper tank 1.1 and the lower tank 1.2 of the pressure tank, and the alloy liquid is sucked into the mold cavity from the melting furnace at a set speed of 50 mm / s until the alloy fills the mold to complete the filling.

[0167] (2) Crust formation and pressure increase: The lower tank 1.2 of the pressure tank continues to admit air, and the air pressure is adjusted separately. The crust formation and pressure increase pressure is 2 KPa, and the crust formation and pressure increase time is 5 s to complete the crust formation and pressure increase.

[0168] (3) Overall pressure increase: The upper tank 1.1 and the lower tank 1.2 of the pressure tank admit air simultaneously, so that the two tanks of the upper tank 1.1 and the lower tank 1.2 of the pressure tank are synchronously pressurized from negative pressure to above 600 KPa within 60 s. During the pressure increase process, it is necessary to ensure that the pressure difference is basically constant to avoid large fluctuations of the alloy liquid up and down in the mold cavity.

[0169] (4) Crystallization pressure increase: The lower tank 1.2 of the pressure tank continues to admit air, and the air pressure is adjusted separately. The crystallization pressure increase pressure is 5 KPa until the crystallization pressure increase is completed.

[0170] (5) Pressure holding and solidification: Hold the pressure for 600 s according to the set time until the casting solidifies under a relatively high pressure.

[0171] (6) Pressure relief: After the pressure holding ends, the upper tank 1.1 and the lower tank 1.2 of the pressure tank exhaust air simultaneously to relieve the pressure to atmospheric pressure, open the upper tank 1.1 of the pressure tank, and take out the mold.

[0172] The process of post-vacuum filling and pressurized solidification for a thin-walled and complex magnesium alloy casing casting. An innovative post-vacuum filling and pressurized solidification process is introduced, and a high-precision gas control system is developed accordingly. Its fast and accurate pressure regulation ability ensures the pressure stability of the molten metal during the filling and solidification processes. The results show that for the castings produced by this process, the dimensional accuracy is improved by 10%, the shrinkage porosity defects are reduced by 15%, and the mechanical properties are enhanced by 15%.

Claims

1. A pressure-adjusting, filling and pressurized solidification device, characterized in that: The invention comprises a pressure tank (1), a lifting mechanism (2), an electric furnace (3), a gas control system (4), an electric control system (5), and a bracket (6); wherein: the pressure tank (1) is further divided into two parts: an upper pressure tank (1.1), a lower pressure tank (1.2), and a middle partition (1.3); the electric furnace (3) is located in the lower pressure tank (1.2); the upper pressure tank (1.1) and the lower pressure tank (1.2) are fixedly connected as a whole through the middle partition (1.3); The upper tank (1.1) of the pressure tank is arranged above the middle partition (1.3); the middle partition (1.3) is arranged above the lower tank (1.2) of the pressure tank; the upper tank (1.1) of the pressure tank, the lower tank (1.2) of the pressure tank and the middle partition (1.3) are connected to form a complete pressure vessel, the sealing ring adopts an O-type fluororubber sealing ring, and the locking structure adopts a wedge-shaped locking to ensure air tightness; the pressure tank (1) adopts a vertical structure; and its pressure range is 0.5-2MPa; The upper tank (1.1) of the pressure tank, the middle partition (1.3) and the lower tank (1.2) of the pressure tank are arranged in the internal space of the frame-type structure bracket (6); the upper tank (1.1) of the pressure tank is arranged on the bracket (6) through a lifting mechanism (2); the lifting mechanism (2) has a hoisting unit and a translation unit; the lifting mechanism (2) is a gantry lifting and translation vehicle + hydraulic system; the lifting mechanism (2) includes a hydraulic lifting mechanism and / or a motor driving mechanism, which can realize accurate positioning of the tank by using motor control; it has the function of lifting and translating the upper tank (1.1) of the pressure tank, the middle partition (1.3) and the low-pressure gasket; the lifting of the upper tank (1.1) of the pressure tank and the middle partition (1.3) is hydraulic lifting; the translation has multi-stage speed control to realize accurate positioning of the tank; The gas control system (4) is connected to the upper pressure tank (1.1) and the lower pressure tank (1.2) in the pressure tank (1); the electric control system (5) is respectively connected to the pressure tank (1), the lifting mechanism (2), the electric furnace (3), the gas control system (4), and the bracket (6); The electric furnace (3) is used to melt the alloy liquid. The electric furnace (3) comprises: a smelting electric furnace (3.1), a crucible (3.2), a liquid riser (3.3), a furnace shell (3.4), and a sealing groove (3.5); the electric furnace (3) is heated by a three-phase power supply, the heating element is a heating resistor belt, the furnace wire is a high-temperature heating belt, and the furnace chamber in the furnace shell (3.4) is a ceramic fiber integrated furnace chamber; the electric furnace (3) has a built-in temperature measuring point; the inlet and outlet pipes of the gas control system (4) are located between the tank body of the pressure tank (1) and the furnace body of the electric furnace (3), and the furnace shell (3.4) of the electric furnace (3) is manufactured separately from the tank body of the pressure tank (1); The pressure tank upper tank (1.1) is hoisted and transported by a lifting mechanism (2). Before pouring, it is hoisted by the lifting mechanism (2) to the top of the electric furnace (3) and dropped to the top of the sand mold; the sand mold is placed above the middle partition (1.3) inside the pressure tank upper tank (1.1).

2. The pressure-adjusting, filling and pressurized solidification device according to claim 1, characterized in that: The pressure-regulating, filling and pressurized solidification device meets the following requirements: The electric furnace (3) is installed in the lower tank (1.2) of the pressure tank; the maximum heating temperature of the electric furnace (3) is 1000-1500°C, the temperature uniformity is ≤±10°C, and the heating power is 50-80kW; The electric furnace (3) has a built-in temperature measuring point, and the surface temperature of the furnace shell is ≤ the ambient temperature + 30°C; The inlet and outlet pipes in the gas control system (4) are located between the tank body and the furnace body, and the furnace body is separated from the tank body.

3. The pressure-adjusting, filling and pressurized solidification device according to claim 2 is characterized in that: The pressure control accuracy of the gas control system (4) during the alloy filling stage is ≤±5KPa, the maximum liquid rising speed during the alloy filling stage is 20-200mm / s, the pressure holding control accuracy is ≤±1KPa, the casting crystallization solidification holding time is: 0-60min, during the solidification pressurization process, the pressure rising speed is ≥100KPa / min, and the deviation between the "pressure difference-time" curve and the set curve is ≤±5KPa.

4. The pressure-adjusting, filling and pressurized solidification device according to claim 3 is characterized in that: Under the cold condition of the empty furnace, the internal vacuum degree of the pressure tank upper tank (1.1) and the pressure tank lower tank (1.2) is required to be 0.1Pa~20KPa; under the working condition, the internal vacuum degree of the upper and lower tanks can be maintained at 0.1KPa~50KPa, and the vacuuming and pressure building time of the inner cavity of the pressure tank upper tank (1.1) and the pressure tank lower tank (1.2) is 0.5~5min; The pressure-regulating, filling and pressurized solidification device adopts a vacuum pump group composed of a rotary vane vacuum pump + a vacuum butterfly valve, and is equipped with a filter, and the ultimate vacuum degree reaches -100KPa; the synchronous inflation, pressure difference building and exhaust after work of the upper tank (1.1) of the pressure tank adopt a digital valve group system, and is provided with an exhaust and air supply system, and the pressurization system adopts a dual system to cooperate with the pressure control to achieve speed tracking and precision tracking; the pressurization system of the lower tank (1.2) of the pressure tank also adopts a digital system to cooperate with the pressure control to achieve speed tracking and precision tracking; the synchronous inflation, low-pressure filling and exhaust after work adopt a digital valve group system, which is provided with air supply and exhaust functions, and the pressurization system adopts a dual system to cooperate with the pressure control to achieve speed tracking and precision tracking; Gas protection, ensure that the flow of 2 gases can be set digitally, and the flow of other circuit gases can be set manually, and enter the gas mixing system at the same time, and the mixed gas is stored in the gas tank; provide at least 4 gas interfaces, different gases can be designed with different flow rates; the mixed gas has a pressurization function, and the pressure after pressurization can be set; configure at least 2 cubic meters of mixed protective gas tanks; configure at least 0.3 cubic meters of melting protective gas tanks; the system has the dual functions of pouring protective gas mixing and melting protective gas mixing; the pouring protective gas has a self-circulating stirring function after being stored for a certain period of time to prevent the high-density gas components from settling. There are monitoring and alarm functions for the gas source used in each circuit and the gas tank pressure.

5. The pressure-adjusting, filling and pressurized solidification device according to any one of claims 1 to 4, characterized in that: The pressure-regulating, filling and pressurized coagulation device is also equipped with a cold-dry filtration system, which adopts three-stage filtration; The temperature control accuracy of the electric control system (5) is ±5°C, and it has a timed heating control function and can automatically start heating according to the setting; The control part of the electric control system (5) is controlled by PLC+industrial computer, and the control part includes a combination of the following functional units: an electric furnace operation control unit, a pressurization control unit, a gas control unit, and a lifting mechanism control unit. In the pressure-regulated filling and pressurized solidification device, the control system adopts the IEC standard and adopts the joint control mode of Siemens PLC + Siemens industrial computer; the locking adopts hydraulic mode, and the opening and closing of the hydraulic valve is controlled by the PLC of the host; the temperature control of the electric furnace adopts temperature control meter + thyristor power regulation + transformer control, and the maximum output power is 90kW. The temperature control meter and the upper computer system communicate through current signals to realize full record of temperature setting collection; the pressure control system realizes double-layer control of boosting and filling and solidification. The filling process adopts the set process tracking curve control, and the solidification boost control adopts the independent joint control of the upper and lower tanks, and the pressure difference is jointly controlled to independently control the respective pressure curves of the upper tank and the lower tank that need to be boosted after filling.

6. The pressure-adjusting, filling and pressurized solidification device according to claim 5, characterized in that: The pressure-regulating, mold-filling and pressurized solidification device is an aluminum liquid filling and pressurized solidification device, which has the following four groups of feedback signal contact functions: Mould bottom, middle liquid level, mould top; The bracket (6) comprises: a gantry frame (6.1) and a sliding wheel (6.2); the bottom sliding wheel (6.2) is arranged at the bottom of the gantry frame (6.1).

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