Static liquid level equipotential difference casting device and control method

Abstract

The invention provides a static liquid level equipotential difference casting device and a control method, the static liquid level equipotential difference casting device comprises a refining furnace, a standing furnace, a casting furnace, a liquid conveying pipe system, various sensors and a PLC control center, the three furnaces are all provided with thermal insulation layers and are sealed, the standing furnace and the casting furnace are both provided with laser range finers for monitoring the liquid level, and the liquid conveying pipe system is provided with a temperature control device. During working, magnesium liquid refined by a smelting furnace is pressed into a crucible of the standing furnace due to pressure difference, and when a working liquid level probe monitors a liquid level signal and a thermocouple monitors a standard temperature signal, the PLC control system controls and automatically matches the rotating frequency of the liquid transfer pump and the rotating frequency of the casting pump through a fuzzy algorithm, so that the siphon liquid volumes of the two pumps are equal; and after the melt is monitored by the die orifice liquid level probe, the pouring nozzle is lifted and closed for casting. Refining, repurifying and casting of the light alloy are achieved through cooperation of the three furnaces, a remelting process is not needed, and the continuous casting process under direct supply of the light alloy liquid is achieved by maintaining potential difference of the liquid level through differential pressure dynamic liquid supplementing.

Description

Technical field

[0001] The present invention relates to the technical field of light alloy die casting, in particular to control and device in magnesium and magnesium alloy die casting. [Background Technology]

[0002] Currently, the die-casting industry's liquid supply system consists of a smelting furnace and a casting system. The smelting furnace melts and refines the alloy into a qualified magnesium alloy melt. The casting system uses pump power or air pressure to move the molten liquid through the casting system channels into the mold cavity for die-casting into magnesium ingots or products. The liquid level difference in the system channels is the driving force behind the melt flow and guarantees quality. However, with each shot from the casting system, the casting pump extracts a certain amount of magnesium melt. Although the smelting furnace replenishes the magnesium ingots at regular intervals, it is difficult to maintain a relatively constant level of magnesium alloy solution during this process. The potential difference inevitably leads to unequal amounts of magnesium melt extracted by the casting pump each time, which inevitably affects the quality of the die-cast parts. Furthermore, the existing direct supply production method for magnesium liquid cannot meet quality and temperature requirements. The transportation of magnesium liquid under heavy loads poses safety risks and technical support challenges.

[0003] The present invention aims to solve the above technical problems and provide a static liquid level equipotential difference casting device and control method. The process is characterized in that: the magnesium ingot is melted and refined separately in the refining furnace, and there is no need to cast the magnesium liquid into ingots and then melt and die-cast it into products. The refining furnace supplies magnesium liquid centrally. Before the magnesium liquid enters the pressing chamber or mold, it is first pressed into the crucible of the static furnace by air pressure. The magnesium liquid is allowed to stand and undergo secondary precipitation purification in the static furnace. It is then siphoned by a liquid transfer pump to the machine-side casting furnace. It is then pumped into the mold cavity by a casting pump for casting, realizing direct supply of magnesium liquid and direct die-casting into parts. In this casting process, a fuzzy control algorithm and a liquid level monitoring program are used to control the pressure difference between the crucibles during the casting process by maintaining the suction volume of the two pumps equal. The pressure difference between the crucibles continuously replenishes the melt in the refining furnace into the crucible of the static furnace to maintain a constant liquid level equipotential difference casting process. To achieve the above object, the present invention adopts the following technical solutions to solve the defects of the prior art and improve the quality of the castings. [Summary of the invention]

[0004] A static liquid surface equipotential difference casting device and control method, the device comprising: a refining furnace, a static furnace, a casting furnace, and a liquid infusion pipe system connecting the furnace room and the mold, a liquid transfer pump and a casting pump, various sensors and a PLC control center. The refining furnace, the static furnace, and the casting furnace are all provided with an insulation layer and are sealed by a sealing cover. In addition, the static furnace and the casting furnace are both equipped with a laser rangefinder for monitoring the liquid level, and the liquid infusion pipe system is also equipped with a temperature control device.

[0005] The static liquid surface equipotential difference casting device and control method include a liquid infusion pipe system in the static liquid surface equipotential difference casting device, including a differential pressure liquid infusion pipe (6), a liquid transfer pipe (5) and a casting pipe (14), wherein the differential pressure liquid infusion pipe (6) is fixedly installed on the sealing covers of the crucibles of the refining furnace (27) and the static furnace (28), one end of the liquid transfer pipe (6) is inserted into the refining furnace crucible at a distance of 250±10 (mm) from the bottom of the crucible, and the other end is 150±10 (mm) from the lower end face of the static furnace cover, forming a melt channel between the refining furnace and the static furnace; the liquid transfer pipe (5) is installed and fixed on the sealing covers of the static furnace crucible (4) and the casting furnace crucible (15). On the top, one end is inserted into the crucible at a distance of 200±10 (mm) from the bottom of the crucible, and the other end is tightly connected to the water outlet of the liquid transfer pump (8) to form a melt channel between the static furnace and the casting furnace; the casting pipe is fixedly installed on the sealing cover of the crucible of the machine-side casting furnace (25), one end is connected to the water outlet of the casting pump (22), and the other end is communicated with the mold cavity of the mold through the nozzle. The casting pipe is fixed to the sealing cover of the casting furnace through a fixed flange and is supported by a support rod (19) fixed to the furnace body. One end of the casting pipe is tightly connected to the water outlet of the casting pump, and the other end is communicated with the mold cavity through the nozzle to form a casting channel.

[0006] The static liquid surface equipotential difference casting device also includes a liquid transfer pump and a casting pump. The two pumps are respectively fixed on both sides of the casting furnace, and the distance between the two pumps is preferably such that the liquid surface does not interfere with each other. The water outlets of the two pumps are located at a depth of 300±10 (mm) of the crucible of the casting furnace.

[0007] The static liquid surface equipotential difference casting device further comprises a refining furnace (27), a static furnace (26) and a machine-side casting furnace (25). The refining furnace (27) is provided with a partition structure having a porous static partition. The heating method can be electric heating or gas heating. The porous static partition (18) is characterized in that it is 100±10 (mm) away from the bottom of the crucible (30) and its two side surfaces are welded to the inner wall of the crucible. The sealing cover of the refining furnace is also provided with a transparent observation hole (23) and a protective gas path device (20). The protective gas path device (2 0), characterized in that it is connected to the protective gas source through a pressure reducing valve; the static furnace (28) includes an outer furnace body (3), a crucible (4) installed in the furnace body, a furnace cover (2) and a laser rangefinder (1) installed thereon; the machine-side casting furnace (25) includes a casting furnace body (22) and a casting furnace crucible (15) installed therein, and a sealing cover (21); the sealing cover (21) is characterized in that a laser rangefinder (9) and three liquid level probes (10, 11, 12) are installed on the sealing cover, which are respectively placed at the upper, middle and lower positions.

[0008] The static liquid surface equipotential difference casting device also includes various sensors, liquid level gauges and a PLC control center for collecting relevant temperature, liquid level, ventilation volume and other information and issuing relevant control instructions.

[0009] The static liquid level equipotential difference casting device and control method described in the present invention also include the following control method: 1) Set and monitor the melt temperature of the refining furnace and casting furnace, and connect the heating and insulation control components to the PLC to control the temperature of the melt, casting pipe, transfer pipe, mold temperature, etc. 2) Set and monitor the mold cavity position and casting volume, and use the casting furnace and mold cavity liquid level detection control components to communicate with the PLC to collect real-time liquid level information to control the rotation frequency and time of the two pumps during the casting process; 3) Set the gas flow rate and ventilation pressure, and use the communication between the protective gas control module and the PLC to control the liquid replenishment pressure. During the die-casting process, a pressure difference is formed between the crucibles to continuously replenish the melt in the refining furnace into the crucible of the static furnace to maintain its liquid level constant. 4) Collect the liquid level information of the insulation casting furnace and the volume information of the casting, calculate the casting volume and the pumping amount and fuzzify them, and look up the table output to determine the rotation frequency and casting speed of the liquid transfer pump and the casting pump. 5) Set the mold cavity heating temperature, connect the mold cavity heating control element and the mold cavity liquid level probe with the PLC communication to regulate the operation of the die casting machine;

[0010] The control method of the static liquid level equipotential difference casting device and control method comprises the following steps: 1) Start the gas system, set the ventilation pressure and gas flow rate by the gas control module, and press the melt in the refining furnace into the static furnace to reach the working liquid level (17); 2) The heat-insulating casting furnace is heated to a preset temperature range. During the heating process of the melt in the casting furnace, the liquid level, temperature and composition of the melt are monitored in real time, and the heating element is turned on and off and the two pumps are started and stopped according to the temperature information and composition; 3) When the liquid level information of the casting furnace reaches the working liquid level (17), and the melt temperature, mold cavity temperature, and nozzle temperature all reach the preset temperature, and the protective gas ventilation pressure reaches the set value, the relevant position heating system is turned off, and the liquid transfer pump, casting pump and casting device are turned on to perform die casting; 4) During the casting process, the control system employs fuzzy control to monitor the magnesium alloy melt level in real time, including the upper and lower limits, as well as the working level. The casting nozzle of the casting device opens for die casting only when, and only when, the working level probe signals and the transfer pump and casting pump simultaneously activate. When the lower limit probe disengages from the liquid level alarm and signals a signal, only the transfer pump rotates to transfer the liquid; when the upper level probe disengages from the liquid level alarm and signals a signal, only the casting pump rotates to cast. When the working level probe detects a signal from the melt, the transfer pump and casting pump pump liquid at a constant rotational frequency, and the die-casting machine casts at constant parameters. The gas control system utilizes a pressure differential to continuously press magnesium into the static furnace to replenish the magnesium liquid and maintain the casting furnace level at a constant working level. The above process, steps 1) to 4), is repeated to continue the continuous casting operation. Both pumps stop operating until the static furnace's laser rangefinder detects the minimum liquid level and signals the static furnace is empty, indicating the static furnace is empty. 5) Regularly observe the refining liquid level through the observation hole (23), add alloy ingots and refining agents to the refining furnace through the feeding port (26), remove slag through the slag removal port to maintain the refining effect, and after the casting is completed, cool the insulation casting furnace to a preset temperature range and prepare for the next die casting.

[0011] The control method of the static liquid level equipotential difference casting device and control method includes the following steps in step 3): 1) Press the refined alloy melt into a static furnace under protective gas until the liquid level reaches the working liquid level; 2) Start the casting device and cast according to the set casting parameters; 3) Manual operation control system, by setting parameters including the two pump frequencies and rotation time, the die casting machine control system sets the casting parameters including casting volume, casting speed, casting temperature, etc., and establishes a fuzzy control rule table; 4) When the liquid level in the casting furnace is lower than the set value of the working liquid level, the PLC control system fine-tunes and increases the frequency of the liquid transfer pump. When the working liquid level is higher than the set value, the PLC control system fine-tunes and increases the frequency of the casting pump. The fuzzy control rule table is checked to dynamically match the casting speed with the pump speed and the casting volume. 5) During the casting process, until the liquid level probe at the mold cavity detects the melt, the control system automatically closes the casting gate and stops casting. The casting transfer system transfers the mold to the cooling station for cooling and other post-processing of the casting. At the same time, a new mold is transferred to the casting station. 6) When the working liquid level, liquid composition, casting temperature and protective gas pressure of the casting furnace are re-monitored and all reach the set values, the control system automatically opens the casting gate and continues casting;

[0012] The control method described in the static liquid level equipotential difference casting device and control method also includes a control system based on the Siemens S7-200 / 300 system platform, which is designed to be a quantitative casting control system based on fuzzy PID adaptive control. To facilitate PLC programming and system operation calculations, this control system first converts a series of fuzzy control rules into a lookup table offline, which is then stored in the PLC lookup table. During online control, the casting parameters are adjusted by the table lookup method.

[0013] Compared with the existing casting device, the present invention has the following effects:

[0014] 1. Using fuzzy algorithm and siphon principle, the liquid level and delivery volume of magnesium liquid are accurately controlled, which greatly shortens the process compared with conventional magnesium alloy smelting and die-casting.

[0015] 2. During the casting process, a pressure difference is formed between the crucibles to continuously replenish the melt in the refining furnace into the crucible of the static furnace, maintaining its liquid level constant and forming a static liquid level equipotential casting environment.

[0016] 3. After the "direct supply of magnesium liquid", the process of remelting the magnesium liquid ingot is omitted, that is, the process of magnesium alloy to product is shortened to: refining in the magnesium alloy melting furnace - magnesium alloy magnesium liquid is directly sent to the static furnace for secondary purification - double pumps siphon the magnesium liquid to the machine-side furnace for die casting - die-casting product post-processing, which saves energy, shortens the process and improves efficiency.

Brief Description of the Drawings

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Attachment Figure 1 Flowchart of the control method of the present invention.

[0019] Attachment Figure 2 PLC fuzzy control casting quantity program flow chart.

[0020] Attachment Figure 3 Communication connection block diagram of the control elements.

[0021] Attachment Figure 4 Schematic diagram of the casting device of the present invention.

[0022] Attachment Figure 5 Schematic diagram of the isolation static plate structure.

[0023] In the figure: 1. Laser rangefinder 2. Standing furnace cover 3. Standing furnace body 4. Standing furnace crucible 5. Liquid transfer tube 6. Differential pressure liquid replenishing tube 7. Pouring nozzle 8. Liquid transfer pump 9. Casting furnace liquid level laser rangefinder 10. Upper liquid level probe 11. Working liquid level probe 12. Lower liquid level probe 13. Casting pump 14. Casting pipe 15. Casting furnace crucible 16. Mold cavity 17. Working liquid level 18. Multi-porous standing furnace partition 19. Casting pipe support rod 20. Vent pipe 21. Casting furnace sealing cover 22. Casting furnace body 23. Transparent observation hole 24. Refining furnace sealing cover 25. Casting furnace 26. Feeding port 27. Refining furnace 28. Standing furnace 29. Casting conveyor line 30. Refining crucible. [Specific implementation method]

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, the terms "casting," "pouring," "die-casting," and "casting" have the same meanings. All other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] It should also be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "designed," "fixed," and "connected" are to be used in a broad sense, and may include, for example, fixed connection, detachable connection, integral connection, mechanical connection, electrical connection, direct connection, indirect connection via an intermediate medium, and internal communication between components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0026] The static liquid surface equipotential difference casting device and control method are described. The static furnaces preferably have more than two corresponding conveying channels and corresponding devices, which can realize multi-machine die casting and magnesium liquid transportation. The magnesium liquid is kept warm and heated in the crucible of the static furnace. Preferably, the holding temperature is 660°C ± 20°C, the casting temperature is 700±20°C, and the mold heating temperature is 200±50°C.

[0027] See attached Figure 3-5 A static liquid surface equipotential difference casting device and control method, the device includes: a refining furnace, a static furnace, a casting furnace and a liquid infusion pipe system connecting the furnace room and the mold, a liquid transfer pump and a casting pump, various sensors and a PLC control center, the refining furnace, the static furnace and the casting furnace are all provided with an insulation layer and are closed by a sealing cover, and the static furnace and the casting furnace are both provided with a laser rangefinder for monitoring the liquid level, and the liquid infusion pipe system is provided with a temperature control device.

[0028] See also Figure 3-4The static liquid surface equipotential difference casting device and control method include a static liquid surface equipotential difference casting device in which a liquid infusion pipe system includes a differential pressure liquid infusion pipe (6), a liquid transfer pipe (5) and a casting pipe (14), wherein the differential pressure liquid infusion pipe (6) is fixedly installed on the sealing covers of the crucibles of the refining furnace (27) and the static furnace (28), one end of the liquid transfer pipe (6) is inserted into the refining furnace crucible at a distance of 250±10 (mm) from the bottom of the crucible, and the other end is 150±10 (mm) from the lower end face of the static furnace cover, forming a melt channel between the refining furnace and the static furnace; the liquid transfer pipe (5) is fixedly installed on the sealing covers of the static furnace crucible (4) and the casting furnace crucible (15). The cover is provided with one end inserted into the crucible at a distance of 200±10 (mm) from the bottom of the crucible, and the other end is tightly connected to the water outlet of the liquid transfer pump (8), forming a melt channel between the static furnace and the casting furnace; the casting pipe is fixedly installed on the sealing cover of the crucible of the machine-side casting furnace (25), one end is connected to the water outlet of the casting pump (22), and the other end is communicated with the mold cavity of the mold through the pouring nozzle. The casting pipe is fixed to the sealing cover of the casting furnace through a fixed flange and is supported by a support rod (19) fixed to the furnace body. One end of the casting pipe is tightly connected to the water outlet of the casting pump, and the other end is communicated with the mold cavity through the pouring nozzle to form a casting channel.

[0029] Preferably, the liquid transfer tube (5) and the inner tube (14) of the casting tube have the same inner diameter.

[0030] The static liquid surface equipotential difference casting device comprises a liquid transfer pump (8) and a casting pump (13), the two pumps are fixed on both sides of the casting furnace respectively, and the distance between the two pumps is preferably such that the liquid levels do not interfere with each other, the water outlets of the two pumps are inserted into the crucible 300±10 (mm) deep, and a porous static partition is added between the pumps. The porous static partition (18) is 100±10 (mm) away from the bottom of the crucible, and the two sides are welded to the inner wall of the crucible. As shown in the attached figure Figure 5 As shown, the surface with the larger opening of the porous static partition faces the liquid transfer pump side.

[0031] Preferably, the liquid transfer pump (8) and the casting pump (13) have the same structure and specifications.

[0032] The static liquid surface equipotential difference casting device comprises a static furnace (28) and a machine-side casting furnace (25), wherein the static furnace comprises an outer furnace body (3), a crucible (4) installed in the furnace body, a furnace cover (2) and a laser rangefinder (1) installed thereon, and the machine-side casting furnace (25) is characterized in that it comprises a casting furnace body (22) and a casting furnace crucible (15) installed therein, a sealing cover (21) and a porous static partition (18), wherein the sealing cover is provided with a laser rangefinder (9) and three liquid level probes (10, 11, 12) respectively arranged at the upper, middle and lower positions, and a protective gas path device (20) is also provided on the sealing cover, wherein the protective gas path device (20) is connected to a protective gas source through a pressure reducing valve, and a casting pipe support rod (19) is also provided on the furnace body.

[0033] Preferably, the liquid level probe and the laser rangefinder are installed in the middle of the crucible cover to facilitate monitoring of the liquid level in the middle of the liquid surface. Preferably, the magnesium alloy liquid level in the crucible is maintained within the range of ±5 mm of the working liquid level, the working liquid level is 150±5 (mm) away from the lower end surface of the crucible cover, the upper liquid level probe is located 100±5 (mm) away from the lower end surface of the crucible cover, the lower liquid level probe is located 200±5 (mm) away from the lower end surface of the crucible cover, and the limit position of the laser rangefinder is set to 200±5 (mm) away from the bottom of the crucible.

[0034] The static liquid surface equipotential difference casting device comprises a PLC control center for receiving and issuing relevant control instructions.

[0035] A static liquid level equipotential difference casting device and control method, further comprising utilizing the static liquid level equipotential difference casting device disclosed by the present invention and adopting the control method described below: 1) Set and monitor the melt temperature of the casting furnace, and connect the heating and insulation control components to the PLC to control the temperature of the melt, casting pipe, transfer pipe, mold temperature, etc. 2) Set and monitor the mold cavity position, static furnace position, and casting volume. Utilize the casting furnace and mold cavity liquid level detection control components to communicate with the PLC, collect liquid level information in real time, and control the rotation frequency and time of the two pumps during the casting process. 3) Set the gas flow rate and ventilation pressure, and use the communication between the protective gas control module and the PLC to control the liquid replenishment pressure. During the die-casting process, a pressure difference is formed between the crucibles to continuously replenish the melt in the refining furnace into the crucible of the static furnace to maintain its liquid level constant. 4) Refer to the attached Figure 1-2 , collect the liquid level information of the insulation casting furnace and the casting volume information, calculate the casting volume and the pumping volume and fuzzy it, and look up the table output to determine the rotation frequency and casting speed of the liquid transfer pump and the casting pump. 5) Set the cavity heating temperature, cavity heating control element and cavity liquid level probe to communicate with PLC to regulate the operation of the die casting machine.

[0036] The present invention discloses a static liquid surface equipotential difference casting device and a control method, wherein the control method comprises the following steps: 1) Starting the gas system, setting the ventilation pressure and gas flow rate by the gas control module, pressing the melt in the refining furnace into the static furnace to reach the working liquid level (17), and heating the heat-insulating casting furnace to a preset temperature range; 2) During the heating process of the melt in the casting furnace, the liquid level, temperature and composition of the melt are monitored in real time, and the heating element is turned on and off and the two pumps are started and stopped according to the temperature information and composition; 3) Refer to the attached Figure 1 When the liquid level information of the casting furnace reaches the working liquid level, and the melt temperature, mold cavity temperature, and nozzle temperature all reach the preset temperature, and the protective gas ventilation pressure reaches the set value, the heating system of the relevant position is turned off, and the liquid transfer pump, casting pump and casting device are turned on for "die casting"; 4) During the casting process, the control system employs fuzzy control to monitor the magnesium alloy melt level in real time, including the upper and lower limits, as well as the working level. The casting nozzle of the casting device opens for die casting only when, and only when, the working level probe signals, the transfer pump and the casting pump simultaneously activate. When the lower limit probe disengages from the liquid level alarm and signals, only the transfer pump rotates to transfer the liquid; when the upper level probe disengages from the liquid level alarm and signals, only the casting pump rotates to cast. When the working level probe detects a signal from the melt, the transfer pump and the casting pump pump liquid at a constant rotational frequency, and the die-casting machine casts at constant parameters. During the die-casting process, a pressure differential is created between the crucibles, continuously replenishing the melt from the refining furnace into the crucible in the standing furnace to maintain a constant liquid level. The above process, steps 1) to 4), is repeated to continue the continuous casting operation. Both pumps stop operating until the standing furnace's laser rangefinder detects the minimum liquid level and signals that the standing furnace is empty. 5) Regularly observe the refining liquid level through the observation hole (23), add alloy ingots and refining agents to the refining furnace through the feeding port (26), remove slag through the slag removal port to maintain the refining effect, and after the casting is completed, cool the insulation casting furnace to a preset temperature range and prepare for the next die casting.

[0037] The static liquid level equipotential difference casting device and control method, wherein step 3) "die casting" in the control method includes the following steps: 1) Press the refined alloy melt into the static furnace until the liquid level in the static furnace reaches the working position; 2) Start the casting device and cast according to the set casting parameters; 3) Manual operation control system, by setting parameters including the two pump frequencies and rotation time, the die casting machine control system sets the casting parameters including casting volume, casting speed, casting temperature, etc., and establishes a fuzzy control rule table; 4) When the liquid level in the casting furnace is lower than the set value of the working liquid level, the PLC control system fine-tunes and increases the frequency of the liquid transfer pump. When the working liquid level is higher than the set value, the PLC control system fine-tunes and increases the frequency of the casting pump. The fuzzy control rule table is checked to dynamically match the casting speed with the pump speed and the casting volume. 5) During the casting process, until the liquid level probe at the mold cavity detects the melt, the control system automatically closes the casting gate and stops casting. The casting transfer system (29) transfers the casting to the cooling station for cooling and other post-processing. At the same time, a new mold is transferred to the casting station; 6) When the working liquid level, liquid composition, casting temperature and protective gas pressure of the casting furnace are re-monitored and all reach the set values, the control system automatically opens the casting gate and continues casting;

[0038] This invention discloses a static liquid level equipotential difference casting device and control method. The control method includes a fuzzy PID adaptive quantitative casting control system designed based on the Siemens S7-200 / 300 system platform. To facilitate PLC programming and system operation calculations, this control method first converts a series of fuzzy control rules into a lookup table offline, which is then stored in the PLC lookup table. During online control, the casting parameters are adjusted using this table lookup method.

[0039] The working process of the present invention is as follows: the control program is started, the magnesium liquid refined by the smelting furnace is pressed into the crucible of the static furnace by air pressure, and the suction pump sucks the magnesium liquid into the casting furnace until the liquid levels in the crucibles of the static furnace (28) and the casting furnace (25) reach the working liquid level (17). The volume of the die casting is input, and when the working liquid level probe monitors the metal liquid signal and the thermocouples at various locations of the system monitor the temperature signal as the set value, the two pumps are started simultaneously, and the rotation frequency of the liquid transfer pump and the casting pump is automatically matched. The PLC control system monitors the liquid level information in real time and controls the fuzzy algorithm to make the volume of the liquid siphoned by the two pumps equal to the volume injected into the mold cavity. After the die mouth liquid level probe monitors the melt, the pouring nozzle is lifted and closed, and the casting is sent to the post-processing station by the conveying system. The empty mold is in place for die casting to continue. During the die casting process, a pressure difference is formed between the crucibles to continuously replenish the melt in the refining furnace into the crucible of the static furnace to maintain its liquid level constant. The casting is completed until the laser rangefinder detects that the liquid level has dropped to the limit low level alarm and shows that the static furnace is "empty". The double pumps stop.

[0040] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that reasonable changes, modifications, variations and even replacements may be made to the embodiments without departing from the principles and spirit of the invention, and the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A static liquid level equipotential difference casting device and control method, the device comprising: Refining furnace, static furnace, casting furnace and the infusion pipe system connecting the furnace room and mold, liquid transfer pump and casting pump, various sensors and PLC control center, refining furnace, static furnace, casting furnace are all equipped with insulation layer and closed by sealing cover, and the static furnace and casting furnace are equipped with laser rangefinders to monitor the liquid level, and the infusion pipe system is equipped with temperature control device.

2. A static liquid level equipotential difference casting device and control method according to claim 1, characterized in that: The liquid infusion pipe system in the static liquid surface equipotential difference casting device comprises a differential pressure liquid infusion pipe (6), a liquid transfer pipe (5) and a casting pipe (14). The differential pressure liquid infusion pipe (6) is fixedly installed on the sealing covers of the crucibles of the refining furnace (27) and the static furnace (28), one end of which is inserted into the crucible of the refining furnace at a distance of 250±10 (mm) from the bottom of the crucible, and the other end is 150±10 (mm) from the lower end face of the static furnace cover, forming a melt channel between the refining furnace and the static furnace; the liquid transfer pipe (5) is fixedly installed on the sealing cover of the static furnace crucible (4) and the casting furnace crucible (15), one end of which is inserted into the crucible at a distance of 250±10 (mm) from the bottom of the crucible. At 200±10 (mm) from the bottom, the other end is tightly docked with the water outlet of the liquid transfer pump (8) to form a melt channel between the static furnace and the casting furnace; the casting pipe is fixedly installed on the sealing cover of the crucible of the machine-side casting furnace (25), one end is docked with the water outlet of the casting pump (22), and the other end is communicated with the mold cavity of the mold through the nozzle. The casting pipe is characterized in that it is fixed to the sealing cover of the casting furnace through a fixed flange and is supported by a support rod (19) fixed to the furnace body. One end of the casting pipe is tightly docked with the water outlet of the casting pump, and the other end is communicated with the mold cavity through the nozzle to form a casting channel.

3. The static liquid surface equipotential difference casting device and control method according to claim 1, characterized in that: The static liquid surface equipotential difference casting device includes a liquid transfer pump and a casting pump. The two pumps are respectively fixed on both sides of the casting furnace. The distance between the two pumps is preferably such that the liquid surface does not interfere with each other. The water outlets of the two pumps are located at a depth of 300±10 (mm) of the crucible of the casting furnace.

4. The static liquid surface equipotential difference casting device and control method according to claim 1, characterized in that: The static liquid surface equipotential difference casting device comprises a refining furnace (27), a static furnace (26) and a machine-side casting furnace (25). The refining furnace (27) is divided into a structure by adding a porous static partition. The heating method can be electric heating or gas heating. The porous static partition (18) is characterized in that it is 100±10 (mm) away from the bottom of the crucible (30) and the two side surfaces are welded to the inner wall of the crucible. The refining furnace sealing cover is also provided with a transparent observation hole (23) and a protective gas path device (20). The protective gas path device (20) is characterized in that The static furnace (28) is characterized in that it includes an outer furnace body (3), a crucible (4) installed in the furnace body, a furnace cover (2) and a laser rangefinder (1) installed thereon; the machine-side casting furnace (25) is characterized in that it includes a casting furnace body (22) and a casting furnace crucible (15) installed therein, and a sealing cover (21); the sealing cover (21) is characterized in that a laser rangefinder (9) and three liquid level probes (10, 11, 12) are installed on the sealing cover at the upper, middle and lower positions, respectively.

5. The static liquid surface equipotential difference casting device and control method according to claim 1, characterized in that: The casting device includes various sensors, liquid level gauges and a PLC control center for collecting relevant temperature, liquid level, ventilation volume and other information and issuing relevant control instructions.

6. A static liquid level equipotential difference casting device and control method according to claims 1-5, characterized in that: The following control methods are also included: 1) Set and monitor the melt temperature of the refining furnace and casting furnace, and connect the heating and insulation control components to the PLC to control the temperature of the melt, casting pipe, transfer pipe, mold temperature, etc. 2) Set and monitor the mold cavity position and casting volume, and use the casting furnace and mold cavity liquid level detection control components to communicate with the PLC to collect real-time liquid level information to control the rotation frequency and time of the two pumps during the casting process; 3) Set the gas flow rate and ventilation pressure, and use the communication between the protective gas control module and the PLC to control the liquid replenishment pressure. During the die-casting process, a pressure difference is formed between the crucibles to continuously replenish the melt in the refining furnace into the crucible of the static furnace to maintain its liquid level constant. 4) Collect the liquid level information of the insulation casting furnace and the volume information of the casting, calculate the casting volume and the pumping amount and fuzzify them, and look up the table output to determine the rotation frequency and casting speed of the liquid transfer pump and the casting pump. 5) Set the cavity heating temperature, cavity heating control element and cavity liquid level probe to communicate with PLC to regulate the operation of the die casting machine.

7. A static liquid level equipotential difference casting device and control method according to claim 6, characterized in that: The control method comprises the following steps: 1) Start the gas system, set the ventilation pressure and gas flow rate by the gas control module, and press the melt in the refining furnace into the static furnace to reach the working liquid level (17); 2) The heat-insulating casting furnace is heated to a preset temperature range. During the heating process of the melt in the casting furnace, the liquid level, temperature and composition of the melt are monitored in real time, and the heating element is turned on and off and the two pumps are started and stopped according to the temperature information and composition; 3) When the liquid level information of the casting furnace reaches the working liquid level (17), and the melt temperature, mold cavity temperature, and nozzle temperature all reach the preset temperature, and the protective gas ventilation pressure reaches the set value, the relevant position heating system is turned off, and the liquid transfer pump, casting pump and casting device are turned on to perform die casting; 4) During the casting process, the control system adopts fuzzy control to monitor the liquid level information of the magnesium alloy melt in real time, including the upper limit, lower limit and working liquid level information. When and only when the working liquid level probe sends a signal and the transfer pump and casting pump are started at the same time, the casting port of the casting device is opened for die casting. When the lower limit probe is separated from the liquid level alarm and sends a signal, only the transfer pump rotates to transfer the liquid. When the upper liquid level probe is separated from the liquid level alarm and sends a signal, only the casting pump rotates to cast. When the working liquid level probe detects the melt and sends a signal, the transfer pump and casting pump pump liquid at a constant rotation frequency, and the die casting machine casts at constant parameters. The gas circuit control system uses the pressure difference to continuously press the magnesium liquid into the static furnace to replenish the magnesium liquid and keep the casting furnace liquid level at a constant working liquid level. Repeat the above process steps 1) to 4) to continue the continuous casting operation. Until the static furnace laser rangefinder detects the extreme low liquid level and sends a signal indicating that the static furnace is "empty", both pumps stop working; 5) Regularly observe the refining liquid level through the observation hole (23), add alloy ingots and refining agents to the refining furnace through the feeding port (26), remove slag through the slag removal port to maintain the refining effect, and after the casting is completed, cool the insulation casting furnace to a preset temperature range and prepare for the next die casting.

8. A static liquid level equipotential difference casting device and control method according to claim 7, characterized in that: Step 3) in the control method includes the following steps: 1) Press the refined alloy melt into a static furnace under protective gas until the liquid level reaches the working liquid level; 2) Start the casting device and cast according to the set casting parameters; 3) Manual operation control system, by setting parameters including the two pump frequencies and rotation time, the die casting machine control system sets the casting parameters including casting volume, casting speed, casting temperature, etc., and establishes a fuzzy control rule table; 4) When the liquid level in the casting furnace is lower than the set value of the working liquid level, the PLC control system fine-tunes and increases the frequency of the liquid transfer pump. When the working liquid level is higher than the set value, the PLC control system fine-tunes and increases the frequency of the casting pump. The fuzzy control rule table is checked to dynamically match the casting speed with the pump speed and the casting volume. 5) During the casting process, until the liquid level probe at the mold cavity detects the melt, the control system automatically closes the casting gate and stops casting. The casting transfer system transfers the mold to the cooling station for cooling and other post-processing of the casting. At the same time, a new mold is transferred to the casting station. 6) When the working liquid level, liquid composition, casting temperature and protective gas pressure of the casting furnace are re-monitored and all reach the set values, the control system automatically opens the casting gate and continues casting.

9. The static liquid level equipotential difference casting device and control method according to claim 1, characterized in that: The control method, which includes a control system based on the Siemens S7-200 / 300 system platform, uses a fuzzy PID adaptive quantitative casting control system. To facilitate PLC programming and system operation calculations, this control method first converts a series of fuzzy control rules into a lookup table offline, which is then stored in the PLC lookup table. During online control, the casting parameters are adjusted using this table lookup method.

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