Liquid level pressurization control system and method for low-pressure casting equipment

Abstract

The invention discloses a liquid level pressurization control system and method for low-pressure casting equipment. The device comprises an air inlet branch, an exhaust branch and a heat preservation furnace, the air inlet branch is connected into the heat preservation furnace through an air inlet and exhaust pipe, the head portion of the air inlet and exhaust pipe is arranged in the heat preservation furnace, the tail portion of the air inlet and exhaust pipe is connected with the air inlet branch, and the tail portion of the air inlet and exhaust pipe is further connected with the exhaust branch. According to the invention, the problem that the height of the metal liquid level in the low-pressure casting holding furnace cannot be controlled and compensated in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid level control, and in particular to a liquid level pressurization control system and method for low-pressure casting equipment. Background Art

[0002] Low-pressure casting is a special casting process between gravity casting and high-pressure casting. It is suitable for aluminum alloy castings with complex production processes and high quality requirements. The core of the process is the pressure and temperature control of the metal liquid rising, filling, and solidification process, in order to obtain a good metallographic structure for the casting. In the entire production process, the liquid surface pressure required for each stage from liquid rising, filling, shrinkage compensation, solidification, etc. is different, and factors such as gas source pressure fluctuations and poor sealing of the insulation furnace will cause the actual liquid surface pressure to change; as production progresses, the consumption of molten metal in the insulation furnace causes the liquid level to drop, gradually increasing the liquid riser height, resulting in a decrease in the internal pressure of the model. Therefore, a system that can control the liquid surface pressure in real time is required to ensure that the liquid surface pressure meets the process requirements during the entire production process.

[0003] At present, most domestic low-pressure casting machines are pressure controlled based on pressure data, but there is no good control and compensation measures for the impact of changes in the metal liquid level in the holding furnace. The following related patent documents introduce various pressure control methods, but none of them can achieve precise control.

[0004] In response to the above problems, invention patent CN101786152B introduces a low-pressure casting machine and its liquid level pressurization control system. The system focuses on the design of the gas circuit system, fails to provide detailed description of pressure detection, and does not analyze and control the impact of changes in the metal liquid level.

[0005] In response to the above problems, invention patent CN104384479A introduces a low-pressure liquid level pressurization control system, which also focuses on the design of the gas circuit system, fails to provide a detailed description of the functions of the four pressure sensors mentioned, and does not analyze and control the impact of changes in the metal liquid level.

[0006] In view of the above problems, the invention patent CN111570763B introduces a low-pressure casting liquid level pressurization system, method and equipment, which mainly targets the potential safety hazards caused by the failure of the pressure sensor. In addition, the heat exchange between the intake and exhaust is used to reduce the impact of pressurized air on the temperature of the aluminum liquid and reduce the exhaust temperature. Its pressure control mode only controls the exhaust action and mold opening action through the data of the pressure relay and the pressure sensor, without pressure control from the intake end, making it difficult to obtain a stable pressurization pressure.

[0007] In view of the above problems, the invention patent CN118404034A introduces a low-pressure casting system and a pressure relief method for low-pressure casting, which detects the liquid level in the riser and the riser basin through a pressure sensor to adjust the opening degree of the exhaust proportional valve, thereby controlling the liquid level drop speed. In this method, the pressure detected by the pressure sensor reflects the height difference between the liquid level in the riser or the riser basin and the liquid level in the insulation furnace, but does not take into account the change in liquid level caused by the consumption of molten metal in the insulation furnace during the production process, resulting in the actual liquid level in the riser or the riser basin not being maintained at the same height under the same pressure value.

[0008] In the related art, there is no effective solution to the problem that the height of the molten metal level in the low-pressure casting holding furnace cannot be controlled and compensated. Summary of the invention

[0009] The purpose of the present invention is to provide a liquid level pressurization control system and method for low-pressure casting equipment to solve the problem that the metal liquid level in the low-pressure casting holding furnace cannot be controlled and compensated in the related art.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] A liquid level pressurization control system for low-pressure casting equipment includes: an air intake branch, an exhaust branch and a holding furnace, wherein the air intake branch is connected to the holding furnace through an air intake and exhaust pipe, the head of the air intake and exhaust pipe is in the holding furnace, the tail of the air intake and exhaust pipe is connected to the air intake branch, and the tail of the air intake and exhaust pipe is also connected to the exhaust branch;

[0012] It is further configured as follows: the air intake branch is provided with an air storage tank, a stop valve, a primary filter, a primary pressure reducing valve, a pressure gauge, a secondary filter, a proportional pressure valve, an electronically controlled stop valve and a one-way valve in sequence from the air intake.

[0013] It is further configured as follows: a pressure gauge is connected to the first-stage pressure reducing valve.

[0014] It is further configured as follows: the exhaust branch is connected to an exhaust filter, a digital proportional valve and a muffler in sequence from the intake and exhaust pipes.

[0015] The further configuration is as follows: a pressure sensor, a high-pressure relay and a low-pressure relay are arranged inside the insulation furnace; a liquid level detection device is arranged on the top of the insulation furnace; a liquid riser is inserted into the insulation furnace, the liquid riser is connected to the model, and the liquid riser is perpendicular to the liquid level in the insulation furnace.

[0016] A method for controlling liquid level pressurization of low-pressure casting equipment comprises: controlling compressed air to enter a holding furnace from an air intake branch; controlling the pressure in the holding furnace so that the detection data in the holding furnace is close to a preset process parameter, and maintaining the pressure, wherein the preset process parameter includes pressure and time; after the pressure maintenance is completed, controlling the liquid level of a liquid riser in the holding furnace to be stable at a preset height; when it is necessary to add molten metal or shut down for a long time, disconnecting the electric control stop valve and opening the digital proportional valve for complete exhaust;

[0017] Furthermore, the compressed air passes through the air storage tank and the stop valve and is roughly filtered through the first-level filter, and then outputs a stable pressure through the first-level pressure reducing valve; the compressed air is finely filtered through the second-level filter, enters the proportional pressure valve, and outputs the set pressure; when the electronically controlled stop valve is opened, the digital proportional valve on the exhaust branch remains closed, and the compressed air enters the holding furnace through the stop valve and the one-way valve.

[0018] Furthermore, the proportional pressure valve is controlled to output pressure so that the molten metal enters the mold from the riser pipe and fills the mold completely.

[0019] Furthermore, the detection data of the pressure sensor is read and compared with the preset process parameters, and the output pressure of the proportional pressure valve is adjusted when a deviation occurs.

[0020] Furthermore, after the pressure holding is completed, the electronically controlled stop valve is closed, and the digital proportional valve is opened for exhaust. At the same time, the pressure data is monitored in real time through the pressure sensor until the pressure drops to the mold opening pressure value, and the digital proportional valve is adjusted to ensure that the liquid level in the riser tube drops steadily to the preset height of the riser tube; the output pressure of the proportional pressure valve is adjusted to the mold opening pressure value, and the digital proportional valve is closed at the same time, and the electronically controlled stop valve is opened, and the gas leakage of the holding furnace is compensated by the output compressed air of the proportional pressure valve, so that the liquid level in the riser tube is stabilized at the preset height.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are:

[0022] 1. Use the gas tank to filter the pressure fluctuations of the workshop power pipeline.

[0023] 2. The pressure sensor in the holding furnace can detect the liquid surface pressure in real time. The change of liquid surface pressure caused by gas leakage due to poor sealing of the holding furnace can be compensated by dynamically adjusting the output pressure of the proportional pressure valve.

[0024] 3. The liquid level detection device in the holding furnace can detect the height of the metal liquid level in real time. As the liquid level in the holding furnace decreases with the consumption of the metal liquid, resulting in an increase in the liquid rise height, compensation can be made by dynamically adjusting the output pressure of the proportional pressure valve.

[0025] 4. During the exhaust process, a digital proportional valve is used to control the exhaust flow rate, which works together with the proportional pressure reducing valve of the air intake branch to reduce the pressure in the holding furnace to the set value. The liquid level in the riser drops to a certain distance from the casting gate to facilitate mold opening and part removal. At the same time, complete pressure relief can be avoided, which will cause the liquid level in the riser to rise and fall sharply, resulting in slag inclusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 A flow chart of a method for controlling liquid surface pressurization of low-pressure casting equipment provided in an embodiment of the present application.

[0029] Figure numerals: 1. gas source; 2. gas storage tank; 3. stop valve; 4. primary filter; 5. primary pressure reducing valve; 6. pressure gauge; 7. secondary filter; 8. proportional pressure valve; 9. electric stop valve; 10. check valve; 11. exhaust filter; 12. digital proportional valve; 13. muffler; 14. insulation furnace; 15. liquid riser; 16. inlet and exhaust pipes; 17. model; 18. liquid level detection device; 19. pressure sensor; 20. high-pressure pressure relay; 21. low-pressure pressure relay. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] Example

[0034] Reference Figure 1 , a liquid level pressurization control system and method for low-pressure casting equipment disclosed in the present invention, the invention comprises: an air intake branch, an exhaust branch and a holding furnace 14, the air intake branch is connected to the holding furnace 14 through an air intake and exhaust pipe 16, the head of the air intake and exhaust pipe 16 is in the holding furnace 14, the tail of the air intake and exhaust pipe 16 is connected to the air intake branch, and the tail of the air intake and exhaust pipe 16 is also connected to the exhaust branch;

[0035] Specifically, the compressed air first enters the gas storage tank 2, and then enters the heat preservation furnace 14 to pressurize the metal liquid surface after being filtered and reduced in pressure in two stages in sequence; a pressure sensor 19 is provided in the heat preservation furnace 14 to measure the liquid surface pressurization pressure data in real time, and a liquid surface detection device 18 is provided to measure the actual liquid surface height data in real time; the detected pressure and height data are transmitted to the control system, which is used as a basis to correct the output pressure of the second-stage pressure reducing valve to ensure that the actual pressure in the model 17 always meets the preset parameter value. When the pressure holding is completed and the mold is opened to take the casting, the pressure of the second-stage pressure reducing valve is first adjusted to the set mold opening pressure value, and then the digital proportional valve 12 of the exhaust branch is opened, and the compressed air in the heat preservation furnace 14 is discharged through the filter and the digital proportional valve 12. When the pressure sensor 19 detects that the liquid surface pressurization pressure is reduced to the set mold opening pressure value, the exhaust is stopped. At this time, the metal liquid level in the riser 15 is reduced to below the gate of the model 17, and is separated from the solidified casting.

[0036] It is further configured as follows: the air intake branch is provided with an air storage tank 2, a stop valve 3, a primary filter 4, a primary pressure reducing valve 5, a pressure gauge 6, a secondary filter 7, a proportional pressure valve 8, an electric control stop valve 9 and a check valve 10 in sequence from the air intake. The primary pressure reducing valve 5 is connected to a pressure gauge 6. The exhaust branch is connected to an exhaust filter 11, a digital proportional valve 12 and a muffler 13 in sequence from the air intake and exhaust pipes 16.

[0037] Specifically, the air intake branch: the air storage tank 2 is used to filter the pressure fluctuation of the workshop power pipeline; the stop valve 3 is used to cut off the connection with the main air circuit when maintaining the equipment. The primary filter 4 is used for coarse filtering, the primary pressure reducing valve 5 is used to obtain a relatively stable pressure of the air source 1, and a pressure gauge 6 is set here to intuitively display the primary pressure value; the secondary filter 7 is used for fine filtering, and the proportional pressure reducing valve is used for secondary pressure reduction, which is used to obtain a stable and accurate air source 1, and the output pressure can be dynamically adjusted by the control system according to the feedback pressure and liquid level data. The electric control stop valve 9 is used to control the on and off of the air circuit; the one-way valve 10 ensures that the air flow can only flow from left to right in one direction. Exhaust branch: the exhaust filter 11 is used to filter the smoke generated in the insulation furnace 14. The digital proportional valve 12 is used to control the exhaust flow rate, and the control system dynamically adjusts the exhaust flow rate according to the feedback pressure and liquid level data, so that the liquid level in the riser 15 can accurately stay at the set position. The muffler 13 is used to reduce the exhaust noise.

[0038] It is further configured as follows: a pressure sensor 19, a high-pressure pressure relay 20 and a low-pressure pressure relay 21 are arranged inside the insulation furnace 14; a liquid level detection device 18 is arranged on the top of the insulation furnace 14; a liquid riser 15 is inserted into the insulation furnace 14, the liquid riser 15 is connected to the model 17, and the liquid riser 15 is perpendicular to the liquid level in the insulation furnace 14.

[0039] Specifically, the in-furnace detection part: during the production process, as the molten metal is consumed, the liquid level will gradually decrease, thereby causing the pressure required for the molten metal to enter the mold 17 to gradually increase; a liquid level detection device 18 is provided in the insulation furnace 14 for real-time detection of the liquid level height. The control system can calculate the height difference from the actual liquid level to the top of the riser 15 based on the liquid level height data, thereby determining the required liquid level pressurization pressure.

[0040] Reference Figure 2 , which is a method for controlling liquid level pressurization of low-pressure casting equipment disclosed in the present invention, and the invention comprises: step S101, controlling compressed air to enter the holding furnace 14 from the air intake branch; step S102, controlling the pressure in the holding furnace 14, making the detection data in the holding furnace 14 close to the preset process parameters, and maintaining the pressure, wherein the preset process parameters include pressure and time; step S103, after the pressure maintenance is completed, controlling the liquid level of the liquid riser 15 in the holding furnace 14 to be stable at a preset height; step S104, when it is necessary to add molten metal or shut down for a long time, disconnecting the electric control stop valve 9, and opening the digital proportional valve 12 for complete exhaust;

[0041] Specifically, in the actual production process, since it is difficult to completely seal the insulation furnace 14, gas leakage will cause the pressure in the insulation furnace 14 to decrease. Therefore, a pressure sensor 19 is provided in the insulation furnace 14 for real-time detection of the pressure in the furnace. When the pressure decreases due to leakage, the control system dynamically adjusts the proportional pressure valve 8 so that the detection data of the pressure sensor 19 is close to the set process parameters. The present invention provides a pressure sensor 19 and two pressure relays in the insulation furnace 14:

[0042] The high-pressure pressure relay 20 is used to detect the upper pressure limit. When the signal is triggered, the control system will sound an alarm, stop the air intake, and start the exhaust function.

[0043] The low-pressure pressure relay 21 is used to detect the lower limit of pressure. When the signal is triggered, it indicates that the pressure in the holding furnace 14 is the same as the atmospheric pressure, and the liquid level in the riser pipe 15 is flush with the metal liquid level in the furnace.

[0044] The pressure sensor 19 is used to detect the real-time pressure data of the whole process; for the detection of the upper and lower pressure limits, it can be used with two pressure relays as a backup. One upper pressure limit signal can trigger the alarm and exhaust; for the lower pressure limit signal, both should be present to judge that the gas pressure in the furnace has dropped to atmospheric pressure. If the two signals are inconsistent, it can be judged as a sensor failure.

[0045] In an optional embodiment, the compressed air passes through the air storage tank 2 and the stop valve 3 and then is roughly filtered through the primary filter 4, and then a stable pressure is output through the primary pressure reducing valve 5; the compressed air is finely filtered through the secondary filter 7, enters the proportional pressure valve 8, and outputs the set pressure; when the electronically controlled stop valve 9 is opened, the digital proportional valve 12 on the exhaust branch remains closed, and the compressed air passes through the stop valve 3 and the one-way valve 10 and enters the insulation furnace 14.

[0046] Specifically, the air storage tank 2 can store a certain amount of compressed air and provide a buffer when demand fluctuates to ensure the stability of the system pressure. The primary pressure reducing valve 5 and the primary filter 4 can reduce and stabilize the pressure of the compressed air while removing large particles of impurities. The secondary filter 7 performs more precise filtering to ensure that the air entering the insulation furnace 14 is clean and free of impurities to avoid contamination of the casting process. The electrically controlled stop valve 9 can accurately control the flow of compressed air. When it is necessary to supply air to the insulation furnace 14, it opens quickly; when it is not needed, it closes to ensure the reliability and safety of the system.

[0047] The proportional pressure valve 8 can accurately adjust the output pressure according to the instructions of the control system to meet the pressure requirements of the molten metal in the holding furnace 14 during the hydraulic lifting and filling process. During the exhaust process, the digital proportional valve 12 can remain closed to prevent compressed air from leaking from the exhaust branch and ensure the stability of the pressure in the holding furnace 14. When exhaust is required, the digital proportional valve 12 can accurately adjust the exhaust volume to achieve a steady drop in pressure. By accurately controlling the pressure and flow of compressed air, the system can avoid unnecessary energy consumption and improve energy efficiency. Stable pressure and clean air can reduce equipment wear and failure rate and extend the service life of the equipment.

[0048] The compressed air after two-stage filtration can ensure that the air entering the holding furnace 14 is clean and free of impurities, avoiding pollution to the casting process. The precise control of the electric control stop valve 9 and the digital proportional valve 12 can prevent the compressed air from leaking when it is not needed, ensuring the safety of the system.

[0049] In an optional embodiment, the proportional pressure valve 8 is controlled to output pressure so that the molten metal flows from the riser pipe 15 into the mold 17 and fills the mold 17 completely.

[0050] In an optional embodiment, the detection data of the pressure sensor 19 is read and compared with the preset process parameters, and when a deviation occurs, the output pressure of the proportional pressure valve 8 is adjusted.

[0051] Specifically, by reading the data of the pressure sensor 19 in real time, the system can quickly capture the current pressure state and compare it with the preset process parameters. Once a deviation is found, the system immediately corrects it by adjusting the proportional pressure valve 8 to ensure that the actual pressure value always remains within the preset range. This instant feedback and adjustment mechanism can significantly reduce the fluctuation of the pressure value and improve the stability of the system. At the same time, since the adjustment is based on accurate measurement data, it can minimize errors and improve the overall control accuracy.

[0052] Different processes may have different pressure requirements. By presetting different process parameters, the system can flexibly respond to various process requirements and ensure that each step is carried out according to the predetermined conditions. Accurate pressure control helps optimize the process and reduce unnecessary energy consumption and waste. For example, in the metal casting process, accurate pressure control can ensure uniform filling of molten metal and improve the quality of castings and production efficiency.

[0053] In an optional embodiment, after the pressure holding is completed, the electronically controlled stop valve 9 is closed, and the digital proportional valve 12 is opened for exhaust. At the same time, the pressure data is monitored in real time through the pressure sensor 19 until the pressure drops to the mold opening pressure value, and the digital proportional valve 12 is adjusted to ensure that the liquid level in the riser pipe 15 drops steadily to the preset height of the riser pipe 15; the output pressure of the proportional pressure valve 8 is adjusted to the mold opening pressure value, and the digital proportional valve 12 is closed at the same time, and the electronically controlled stop valve 9 is opened, and the gas leakage of the holding furnace 14 is compensated by the output compressed air of the proportional pressure valve 8, so that the liquid level of the riser pipe 15 is stabilized at the preset height.

[0054] Specifically, the process of low-pressure casting is to press the molten metal in the holding furnace 14 into the cavity of the upper mold through the liquid riser 15, and form a casting after cooling. After the mold is opened, the casting is taken away, and then the next one is produced. Each time a casting is produced, the molten metal in the holding furnace 14 will be reduced. As the production progresses, the molten metal in the holding furnace 14 will become less and less, and the liquid level will gradually decrease.

[0055] The pressure measured by the pressure sensor 19 in the reference document reflects the height difference between the liquid level in the liquid riser 15 or the liquid riser basin and the liquid level in the holding furnace 14. If the liquid level in the holding furnace 14 remains unchanged, this method can measure the actual height of the liquid level in the liquid riser 15 or the liquid riser basin. However, in the actual production process, the liquid level in the holding furnace 14 gradually decreases, so the error of the measurement result will become larger and larger.

[0056] This solution measures the actual height of the liquid level in the holding furnace 14 through the liquid level detection device 18, and then calculates the pressure difference required to control the liquid level in the riser pipe 15 at a certain height, thereby adjusting the output pressure of the proportional pressure valve 8. As the liquid level gradually decreases, the height difference between the liquid level in the riser pipe 15 and the liquid level in the holding furnace 14 gradually increases, and the output pressure of the proportional pressure valve 8 also gradually increases, which can ensure that the liquid level in the riser pipe 15 is always maintained at the same height.

[0057] The working principle and beneficial effects of the present invention are as follows: compressed air first enters the gas storage tank 2, and then enters the heat preservation furnace 14 to pressurize the metal liquid surface after being filtered and reduced in pressure in two stages in sequence; a pressure sensor 19 is provided in the heat preservation furnace 14 to measure the liquid surface pressurization pressure data in real time, and a liquid surface detection device 18 is provided to measure the actual liquid surface height data in real time; the detected pressure and height data are transmitted to the control system, which is used as a basis to correct the output pressure of the second-stage pressure reducing valve to ensure that the actual pressure in the model 17 always meets the preset parameter value. When the pressure is finished and the mold is opened to take the casting, the pressure of the second-stage pressure reducing valve is first adjusted to the set mold opening pressure value, and then the digital proportional valve 12 of the exhaust branch is opened, and the compressed air in the heat preservation furnace 14 is discharged through the filter and the digital proportional valve 12. When the pressure sensor 19 detects that the liquid surface pressurization pressure is reduced to the set mold opening pressure value, the exhaust is stopped. At this time, the metal liquid level in the riser 15 is reduced to below the gate of the model 17, and is separated from the solidified casting.

[0058] The advantages of this solution are:

[0059] 1. Use gas tank 2 to filter the pressure fluctuation of the workshop power pipeline.

[0060] 2. The pressure sensor 19 in the holding furnace 14 can detect the liquid surface pressure in real time. The change of liquid surface pressure caused by gas leakage due to poor sealing of the holding furnace 14 can be compensated by dynamically adjusting the output pressure of the proportional pressure valve 8.

[0061] 3. The liquid level detection device 18 in the holding furnace 14 can detect the height of the metal liquid level in real time. As the liquid level in the holding furnace 14 decreases with the consumption of the metal liquid, resulting in an increase in the liquid rise height, the output pressure of the proportional pressure valve 8 can be dynamically adjusted to compensate.

[0062] 4. During the exhaust process, a digital proportional valve 12 is used to control the exhaust flow rate, which works together with the proportional pressure reducing valve of the air intake branch to reduce the pressure in the holding furnace 14 to a set value. The liquid level in the riser pipe 15 drops to a certain distance away from the casting gate to facilitate mold opening and part removal. At the same time, complete pressure relief is avoided, which causes the liquid level in the riser pipe 15 to rise and fall sharply, resulting in slag inclusion.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid level pressurization control system for low-pressure casting equipment, characterized in that: include: An air intake branch, an exhaust branch and a heat preservation furnace (14), wherein the air intake branch is connected to the heat preservation furnace (14) via an air intake and exhaust pipe (16), the head of the air intake and exhaust pipe (16) is inside the heat preservation furnace (14), the tail of the air intake and exhaust pipe (16) is connected to the air intake branch, and the tail of the air intake and exhaust pipe (16) is also connected to the exhaust branch.

2. A liquid level pressurization control system for low-pressure casting equipment according to claim 1, characterized in that: include: The air intake branch is provided with an air storage tank (2), a stop valve (3), a primary filter (4), a primary pressure reducing valve (5), a pressure gauge (6), a secondary filter (7), a proportional pressure valve (8), an electric control stop valve (9) and a one-way valve (10) in sequence from the air intake.

3. A liquid level pressurization control system for low-pressure casting equipment according to claim 2, characterized in that: include: The first-stage pressure reducing valve (5) is connected to a pressure gauge (6).

4. A liquid level pressurization control system for low-pressure casting equipment according to claim 1, characterized in that: include: The exhaust branch is connected to an exhaust filter (11), a digital proportional valve (12) and a muffler (13) in sequence from the inlet and exhaust pipes (16).

5. A liquid level pressurization control system for low-pressure casting equipment according to claim 1, characterized in that: include: The insulation furnace (14) is provided with a pressure sensor (19), a high-pressure pressure relay (20) and a low-pressure pressure relay (21); A liquid level detection device (18) is provided on the top of the heat preservation furnace (14); A liquid riser (15) is inserted into the heat-insulating furnace (14), the liquid riser (15) is connected to the model (17), and the liquid riser (15) is perpendicular to the liquid surface in the heat-insulating furnace (14).

6. A method for controlling liquid level pressurization of low-pressure casting equipment, applied to a liquid level pressurization control system of low-pressure casting equipment as described in any one of claims 1 to 5, characterized in that: include: Controlling compressed air to enter the holding furnace (14) from the air inlet branch; Controlling the pressure in the holding furnace (14) so ​​that the detection data in the holding furnace (14) is close to the preset process parameters, and maintaining the pressure, wherein the preset process parameters include pressure and time; After the pressure maintenance is completed, the liquid level of the liquid riser (15) in the heat preservation furnace (14) is controlled to be stable at a preset height; When it is necessary to add molten metal or shut down for a long time, the electric control stop valve (9) is disconnected and the digital proportional valve (12) is opened to completely exhaust the gas.

7. A method for controlling liquid level pressurization of low-pressure casting equipment according to claim 6, characterized in that: include: The compressed air passes through the air storage tank (2) and the stop valve (3), and then passes through the primary filter (4) for coarse filtration, and then outputs a stable pressure through the primary pressure reducing valve (5); The compressed air is finely filtered by a secondary filter (7) and enters a proportional pressure valve (8) to output a set pressure. When the electric control stop valve (9) is opened, the digital proportional valve (12) on the exhaust branch line remains closed, and the compressed air enters the holding furnace (14) through the stop valve (3) and the one-way valve (10).

8. A method for controlling liquid level pressurization of low-pressure casting equipment according to claim 6, characterized in that: include: The output pressure of the proportional pressure valve (8) is controlled so that the molten metal flows from the riser pipe (15) into the mold (17) and fills the mold (17).

9. A method for controlling liquid level pressurization of low-pressure casting equipment according to claim 8, characterized in that: include: The detection data of the pressure sensor (19) is read and compared with the preset process parameters, and when a deviation occurs, the output pressure of the proportional pressure valve (8) is adjusted.

10. A method for controlling liquid level pressurization of low-pressure casting equipment according to claim 6, characterized in that: include: After the pressure maintenance is completed, the electric control stop valve (9) is closed, and the digital proportional valve (12) is opened to exhaust gas, and at the same time, the pressure data is monitored in real time through the pressure sensor (19) until the pressure drops to the mold opening pressure value, and the digital proportional valve (12) is adjusted to ensure that the liquid level in the liquid riser (15) drops steadily to the preset height of the liquid riser (15); The output pressure of the proportional pressure valve (8) is adjusted to the mold opening pressure value, and at the same time, the digital proportional valve (12) is closed and the electric control stop valve (9) is opened. The compressed air output by the proportional pressure valve (8) is used to compensate for the gas leakage of the insulation furnace (14), so that the liquid level of the riser pipe (15) is stabilized at a preset height.

Images