Differential pressure casting mold filling monitoring and solidification parameter testing system and control method

Abstract

The present invention discloses a system for monitoring mold filling and testing solidification parameters during differential pressure casting, belonging to the field of differential pressure casting technology. The system comprises a lower tank body; an upper tank body; a middle partition; at least one gas source; a riser pipe; a thermal sensor that transmits temperature information to a PLC system to control pressure changes; a temperature testing system comprising thermocouples arranged at different heights within the upper tank body and a multi-channel thermometer connected to the thermocouples. The multi-channel thermometer detects and records the temperature changes at different locations within the tank body over time and transmits the temperature information to the PLC system to form a temperature curve; and a pressure-sensitive sensing system that transmits pressure information from the lower tank body cavity to the PLC system to monitor and control pressure changes during the differential pressure casting process. Applicable to light alloy differential pressure casting, the present invention ensures smooth mold filling, effectively controls differential pressure parameters, and prevents equipment failures caused by sparks.

Description

Technical Field

[0001] The present invention belongs to the technical field of differential pressure casting, and in particular relates to a differential pressure casting mold filling monitoring and solidification parameter testing system and control method. Background Art

[0002] With the development of aviation, aerospace, and equipment manufacturing, cast aluminum alloys, as traditional metal materials, are widely used in various industries, including aviation, aerospace, automotive, and machinery, due to their low density and high specific strength. They hold immense promise. Consequently, research on cast aluminum alloys encompasses many aspects, including the role of alloying elements in the alloy, optimization of alloy composition and research into new alloys, alloy smelting, alloy refining, alloy grain refinement, and modification of aluminum-silicon alloys. Traditional casting methods struggle to meet the demands for larger, thinner, more complex, and more integrated aluminum alloy castings. Consequently, new casting methods and process monitoring remain essential to further improve alloy performance and ensure the production of qualified castings. However, in the actual production of aluminum alloy castings, defects such as porosity, pinholes, cracks, shrinkage, porosity, deformation, cold shuts, undercasting, sand inclusions, and flashover can occur. Due to the diverse structure of parts and materials used, the various defects can vary from casting to casting.

[0003] Differential pressure casting, a counter-gravity casting method, completes shell solidification under high pressure. This effectively eliminates pinhole defects in aluminum alloys and reduces the occurrence of other defects, while also enhancing the shrinkage feeding capacity of the molten metal. It is widely used in large-scale cabin casting. To better ensure casting quality and yield, the differential pressure casting mold must maintain stable pressure and temperature conditions, and the interfacial heat transfer coefficient must be calculated.

[0004] Chinese patent CN114226690A discloses a control method and casting device for aluminum alloy differential pressure casting, comprising a casting furnace, a casting upper tank, a crucible, a sealing mechanism, and a monitoring mechanism. The casting furnace and the casting upper tank are connected to form a sealed tank body by a detachable mechanism. The control method and casting device for aluminum alloy differential pressure casting can monitor the air pressure in the casting upper tank and the casting furnace in real time through the monitoring mechanism. The upper tank pressure control mechanism and the pressure measuring mechanism cooperate to achieve constant pressure control for the casting upper tank, and the lower tank pressure control mechanism and the pressure measuring mechanism cooperate to achieve constant pressure control for the casting furnace. This ensures stable control of the solidification pressure of the differential pressure casting upper tank, ensuring that the required pressure for differential pressure casting can be set according to demand and maintained stable, improving the solidification conditions of the casting under different pressures, and being able to be set according to demand, thereby improving the casting accuracy.

[0005] However, the above-mentioned control method and casting device for aluminum alloy differential pressure casting only monitor and feedback the air pressure in the tank body. It cannot effectively monitor the temperature field of the molten metal at different positions and times during the casting process, nor can it obtain the interface heat transfer coefficient of different heights and different thicknesses of the casting, and cannot regulate the overall solidification sequence of the casting. Summary of the Invention

[0006] The details of one or more embodiments of the invention are set forth in the following drawings and description to make other features, objects, and advantages of the application more readily apparent.

[0007] The present invention proposes a differential pressure casting casting filling monitoring and solidification parameter testing system, which solves the above-mentioned problems existing in the prior art. It can monitor the temperature field of the molten metal at different positions and times during the sand core casting process, and calculate the interface heat transfer coefficient of the casting at different height positions, structural thick positions, etc., to ensure smooth filling and reduce the probability of defects in the casting. It can effectively monitor the pressure changes in the differential pressure process. When the pressure slope is greater than a set value, it will release the pressure through rapid exhaust to minimize the risk of equipment failure caused by mold fire.

[0008] On the one hand, the present invention discloses a differential pressure casting casting filling monitoring and solidification parameter testing system, comprising a lower tank body, installed on a pit cement foundation, the lower tank body being used to install a crucible insulation furnace filled with molten metal; an upper tank body, installed above the lower tank body, the upper tank body being used to place a casting mold; a middle partition, installed between the lower tank body and the upper tank body, the middle partition dividing the upper tank body and the lower tank body into two independent sealed spaces by a rotary seal; at least one gas source, connected to the upper tank body and the lower tank body respectively through an air flow pipe; a liquid riser, passing through the middle partition to introduce the molten metal in the crucible insulation furnace into the casting mold; a temperature testing system, comprising a temperature measuring device arranged on the upper tank body, Thermocouples at different heights in the tank body and a multi-channel thermometer connected to the thermocouples, the multi-channel thermometer detects and records the temperature signals of different positions in the upper tank body that change with time and transmits them to the PLC system to form a temperature curve; a pressure-sensitive sensing system is connected to the inner cavity of the lower tank body, the pressure-sensitive sensing system transmits the pressure information of the inner cavity of the lower tank body to the PLC system to determine the slope of the pressure change in the inner cavity and control the pressure change during the filling process of the differential pressure casting; thermistors are evenly distributed on the bottom of the upper tank body and the circumference of the sealing surface of the middle partition, the thermistors transmit temperature information to the PLC system to control the pressure relief when the temperature in the upper tank body is abnormal.

[0009] In some embodiments, the thermocouples are respectively arranged at the interface between the resin sand shape, the contact interface between the external chiller and the molten metal, and the interface between different heights and thick parts of the casting and the molten metal position.

[0010] In some embodiments, the crucible insulation furnace further includes refractory bricks laid on the bottom of the lower tank body; a main body support frame arranged on the refractory bricks, and the main body support frame and the refractory bricks form a furnace cavity; a crucible arranged on the furnace cavity, and the molten metal is placed inside the crucible; and an insulation cover arranged on the top of the crucible.

[0011] In some embodiments, the casting mold further includes a sand box, which is arranged on the middle partition and filled with resin sand and a cooling system; a sand core, which is arranged in the sand box according to the tooling and the chiller.

[0012] In some embodiments, the temperature testing system further comprises a thermocouple protection sleeve, which is inserted into the molten metal through the insulation cover.

[0013] In some embodiments, the differential pressure casting casting filling monitoring and solidification parameter testing system also includes a plurality of valve bodies, the valve bodies are connected to the inner cavity of the tank body, and the valve bodies further include an air inlet valve, which is respectively connected to the inner cavity of the lower tank body and the upper tank body; an exhaust valve, which is respectively connected to the inner cavity of the lower tank body and the upper tank body, and the exhaust valve exhausts and releases pressure after the pressure maintaining is completed; a gas intercommunication valve, which is respectively connected to the lower tank body and the upper tank body, and the gas intercommunication valve ensures pressure balance between the two tank bodies during the inflation process; a safety valve, which is arranged on the top of the upper tank body and is connected to the interior of the upper tank body, and the safety valve is used to ensure that the pressure in the upper tank does not exceed the safety threshold.

[0014] Another aspect of the present invention discloses a control method for the differential pressure casting mold filling monitoring and solidification parameter testing system, comprising the following steps:

[0015] Differential pressure casting mold filling monitoring: During the differential pressure casting filling process, when the molten metal fills the mold from the bottom of the mold cavity along the pouring system from bottom to top, the molten metal contacts multiple thermocouples from bottom to top over time. The multi-channel temperature measuring instrument transmits the temperature signals of the thermocouples at different positions in the tank body to the PLC system to generate a temperature curve.

[0016] Differential pressure casting parameter design: Based on the temperature curve, the height difference ΔH of the different thermocouple settings is divided by the time difference ΔT of the thermocouple temperature change at different times to calculate the filling rate of the molten metal at different height interfaces. The pressure increase and exhaust rate of the differential pressure equipment are adjusted through the PLC system to make the filling rates of different height interfaces as close as possible;

[0017] Solidification parameter monitoring: Based on the temperature curve, determine whether different positions of the casting can solidify as simultaneously as possible or solidify from top to bottom. If the above conditions cannot be met, adjust the cooling system to make different heights or thicker parts of the casting solidify as simultaneously as possible or solidify from top to bottom.

[0018] In some embodiments, a pressure monitoring step is further included: the pressure-sensitive sensing system transmits the pressure information of the inner cavity of the tank to the PLC system. When the pressure in the tank is momentarily greater than the process set value, the PLC system receives the signal and feeds it back to the exhaust valve, causing the exhaust valve to open and quickly release the pressure;

[0019] In some embodiments, a fire monitoring step is also included: when a fire occurs, the molten metal touches the thermistor and the temperature is greater than 200°C, the thermistor transmits the temperature information to the PLC system and then feeds it back to the exhaust valve, causing the exhaust valve to open and quickly release pressure.

[0020] In some embodiments, the differential casting casting also includes the following steps before filling the mold: placing the riser tube into the preset center hole position of the middle partition, inserting it into the crucible to form the molten metal channel, moving the upper tank body to the middle partition to form a sealed tank body, opening the air inlet valve to inflate until the air pressure of the upper tank body and the lower tank body is balanced, opening the exhaust valve connected to the upper tank body to exhaust and reduce pressure, and under the action of the pressure of the lower tank body, the molten metal inside the crucible rises along the riser tube and enters the casting cavity.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a differential pressure casting filling monitoring and solidification parameter testing system. The multi-channel temperature measuring instrument transmits the temperature signals of thermocouples at different positions in the tank body that change with time to the PLC system, generates a temperature curve, and adjusts the cooling system to make different heights or thicker parts of the casting solidify as simultaneously as possible or solidify from top to bottom, thereby ensuring smooth filling. The pressure sensitive sensing system transmits the inner cavity pressure information to the terminal PLC system to determine the slope of the inner cavity pressure change and control the pressure change during the differential pressure casting filling process, thereby preventing equipment failure caused by sparking. When sparking occurs and the molten metal touches the thermistor, the thermistor transmits the temperature information to the terminal PLC system and then feeds it back to the exhaust valve for exhaust and pressure relief, thereby preventing equipment failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1A schematic diagram of the structure of a differential pressure casting mold filling monitoring and solidification parameter testing system provided by an embodiment of the present invention;

[0025] Description of the drawings: 1. Lower tank body, 2. Bottom refractory bricks, 3. Main body support frame, 4. Crucible, 5. Molten metal, 6. Gas interconnecting valve, 7. Riser, 8. Middle partition, 9. Sand box, 10. Mold, 11. Sand core, 12. Upper tank body, 13. Safety valve, 14. Insulation cover, 15. Exhaust valve, 16. Multi-channel thermometer, 17. Thermocouple, 18. Thermocouple protection cover, 19. Inlet valve, 20. Pressure sensitive sensor system, 21. Thermistor, 22. Alarm. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0027] Obviously, the drawings described below are merely examples or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar scenarios based on these drawings without inventive effort. Furthermore, it is understood that while the effort involved in such a development process may be complex and lengthy, for those skilled in the art related to the disclosure of the present invention, any design, manufacturing, or production changes based on the technical content disclosed in the present invention are merely conventional technical means and should not be construed as an inadequacy of the disclosure of the present invention.

[0028] References to "embodiments" in this disclosure mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this disclosure may be combined with other embodiments, unless there is a conflict.

[0029] Unless otherwise defined, technical or scientific terms used in the present invention shall have the ordinary meaning understood by persons of ordinary skill in the art to which the invention pertains. The terms "a," "an," "a kind," "the," and the like as used in the present invention do not limit the number and may refer to the singular or the plural. The terms "include," "comprises," "has," and any variations thereof as used in the present invention are intended to cover non-exclusive inclusions; for example, a process, method, system, product, or device comprising a series of steps or modules (units) is not limited to the listed steps or units but may also include steps or units not listed, or may also include other steps or units inherent to such process, method, product, or device. The terms "connected," "connected," and the like as used in the present invention are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. The term "plurality" as used in the present invention refers to two or more. "And / or" describes the association relationship between associated objects, indicating that three relationships may exist. For example, "A and / or B" may represent: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", etc. involved in the present invention are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0030] The embodiment of the present invention provides a system for monitoring the filling process and testing the solidification parameters of differential pressure castings, and in particular relates to monitoring the filling process and determining and testing the solidification parameters of light alloy differential pressure castings. Figure 1 Schematic diagram of the structure of the differential pressure casting filling monitoring and solidification parameter testing system according to an embodiment of the present invention. Figure 1As shown, the differential pressure casting casting filling monitoring and solidification parameter testing system includes: a tank body, the tank body includes a lower tank body 1 and an upper tank body 12, wherein the lower tank body 1 is installed on the pit cement foundation, and the lower tank 1 is used to install a crucible insulation furnace filled with molten metal; the crucible insulation furnace further includes a bottom refractory brick 2, which is laid on the bottom of the lower tank body 1; a main body support frame 3, which is arranged on the bottom refractory brick 2 and is used to fix the furnace wire, and the main body support frame 3 and the bottom refractory brick 2 form a furnace cavity; a crucible 4, which is arranged on the top steel plate of the furnace cavity and is used to smelt the alloy, and the crucible 4 is filled with molten metal 5; an insulation cover 14, which is arranged on the top of the crucible 4 and is used to isolate excess heat from dissipation; an upper tank body 12, which is installed above the lower tank body 1, and the upper tank body 12 has a movable function through a gantry structure. When the upper tank body 12 is working, it is locked on the middle partition 8 to form an independent sealed space, and a casting mold 10 is placed in the upper tank body 12. A middle partition 8 is installed between the lower tank body 1 and the upper tank body 12. The middle partition 8 is sealed by rotation, so that the two tank bodies form two independent sealed spaces when the valve body is closed. The riser pipe 7 is installed in the center of the middle partition 8 and penetrates into the molten metal 5 contained in the crucible 4 through the middle partition 8 to ensure that the molten metal 5 can smoothly enter the mold cavity through the back pressure. The riser pipe 7 guides the molten metal 5 in the crucible 4 into the casting mold. The casting mold 10 further includes a sand box 9, which is arranged on the middle partition 8. The sand box 9 is filled with resin sand and a cooling system to form an external structure; a sand core 11, which is arranged in the sand box 9. The sand core 11 forms the inner cavity of the product according to the tooling and the cold iron arrangement. The sand core 11 is combined with the sand box 9 to form the product blank cavity. After the whole box is assembled, it is placed on the middle partition 8.

[0031] The differential pressure casting casting filling monitoring and solidification parameter testing system in the embodiment of the present invention also includes at least one gas source, which is respectively connected to the upper tank body and the lower tank body through an air flow pipe; a plurality of valve bodies, which are connected to the inner cavity of the tank body, and the valve body further includes an air inlet valve 15, which is respectively connected to the inner cavity of the lower tank body 1 and the upper tank body 12; an exhaust valve 15, which is respectively connected to the inner cavity of the lower tank body 1 and the upper tank body 12, and is used to exhaust and release pressure after the pressure maintenance is completed; a gas interconnecting valve 6, which is respectively connected to the lower tank body 1 and the upper tank body 12, and ensures pressure balance between the two tank bodies during the inflation process; a safety valve 13, which is arranged at the top of the upper tank body 12 and is connected to the interior of the upper tank body 12, to ensure that the pressure in the upper tank body 12 does not exceed the safety threshold.

[0032] In the embodiment of the present invention, the differential pressure casting casting filling monitoring and solidification parameter testing system also includes a temperature testing system, including thermocouples 17 arranged at different heights in the tank body and a multi-channel temperature measuring instrument 16 connected to the thermocouple 17, the thermocouple 17 is a plurality of K-type thermocouples, and a high-temperature resistant ceramic thermocouple protective cover 18 is arranged outside the K-type thermocouple, and the thermocouple protective cover 18 passes through the reserved hole set on the top of the insulation cover 14 and penetrates into the molten metal 5; the K-type thermocouple respectively fixes the resin sand outer surface interface, the contact interface between the external cold iron and the molten metal, the interface between the thick and large parts at different heights and the molten metal position, etc. The multi-channel temperature measuring instrument 16 is connected to the K-type thermocouple, and the temperature detected and recorded by the K-type thermocouple at different positions in the tank body that changes with time is transmitted to the terminal PLC system to form a temperature curve. The pressure-sensitive sensing system 20 is connected to the interior of the upper tank 12 and / or the interior of the lower tank 1. The pressure-sensitive sensing system 20 transmits the internal pressure information to the terminal PLC system. The PLC system and computer monitor and control the pressure changes during the differential pressure process by determining the slope of the internal pressure change. When the pressure momentarily exceeds the safety factor required by the process design, the PLC system feeds back a signal to the exhaust valve 15, causing it to open and quickly release pressure to prevent equipment failure caused by fire. Thermal sensors 21 are evenly distributed and installed on the sealing surface between the bottom of the upper tank 12 and the middle partition 8. The thermal sensors 21 are connected to the terminal PLC system and transmit temperature information within the upper tank 12 to the terminal PLC system. Generally, the temperature around the sand box 9 does not exceed 100°C during pouring, and the regional temperature is between 300 and 500°C during fire. When fire occurs and the molten metal 5 touches the thermistor 21 and the temperature is greater than 200°C, the thermistor 21 transmits the temperature information to the terminal PLC system and then feeds it back to the exhaust valve 15, causing the exhaust valve 15 to open and quickly release the pressure. At the same time, the terminal PLC system feeds back the abnormal signal to the alarm 22, and the alarm 22 flashes to warn, thereby preventing equipment failure caused by fire.

[0033] The differential pressure casting mold filling monitoring and solidification parameter testing system of the present invention can monitor the temperature field of the molten metal at different positions and times during the sand core casting process, and can effectively monitor the pressure changes during the differential pressure process. Since the pressure will suddenly change during a fire, when the pressure slope is greater than a set value, the pressure is released by rapid exhaust to prevent the mold from causing equipment failure to the greatest extent; by monitoring the filling position and solidification temperature curve of the process, the differential pressure pouring parameters are reasonably designed, and the interface heat transfer coefficients of different height positions and thick structure positions of the casting are calculated, so as to provide a basis for subsequent products to use software to simulate the solidification process of the casting and judge its solidification sequence, temperature field and final solidification area, thereby reducing the probability of defects in the casting, and maximizing the guarantee that the equipment is damaged by the fire during the casting process, and better guaranteeing the quality of the casting and the yield rate.

[0034] The present invention also provides a control method for the above-mentioned differential pressure casting casting filling monitoring and solidification parameter testing system, including a differential pressure casting filling position monitoring step, a differential pressure casting parameter design step, a solidification parameter monitoring step, and / or a pressure monitoring step, and / or a fire monitoring step. Specifically, a quick connector is provided at the required position of the mold 10 and the sand core 11, a thermocouple 17 is reserved, and the outside of the sand box 9 is extended. After the casting is molded, the qualified crucible 4 is lifted to the lower tank body 1 and the middle partition 8 is closed. The liquid riser 7 is placed in the center hole position of the middle partition 8 and inserted into the crucible 4. The mold 10 is lifted to the limited position of the middle partition 8, and the thermocouple quick connector reserved on the differential pressure tank is quickly connected. The upper tank body 12 is moved to close the tank body, and the air inlet valve 19 is opened to inflate. When the air pressure of the upper tank body 12 is balanced with that of the lower tank body 1, the exhaust valve 15 connected to the upper tank body 12 is opened to exhaust and reduce pressure, and the pressure difference is used to lift the liquid, fill the mold, increase the pressure, and maintain the pressure.

[0035] When the molten metal is filled from the bottom of the mold 10 along the pouring system from bottom to top, the thermocouple 17 set at the bottom of the mold 10 first contacts the molten metal, and the temperature fluctuation occurs first at the thermocouple 17 at this position. As time changes, the molten metal 5 contacts multiple thermocouples 17 from bottom to top in sequence. The multi-channel temperature measuring instrument 16 transmits the temperature signals of the thermocouples at different positions in the tank body that change with time to the PLC system to generate a temperature curve to determine whether different positions of the casting can solidify as simultaneously as possible or solidify from top to bottom. If the above conditions cannot be met, By adjusting the cooling system, different heights or thick parts of the casting are solidified as much as possible at the same time or from top to bottom, and the interface heat transfer coefficients at different heights and thick parts of the casting are calculated; the height difference ΔH of different thermocouple 17 settings is divided by the time difference ΔT of the temperature change of the thermocouple 17 at different times to calculate the filling rate of the molten metal 5 at different heights. By measuring the filling rate of interfaces at different heights, the boost and exhaust rates of the differential pressure equipment are adjusted to make the filling rates of interfaces at different heights as close as possible to ensure smooth filling;

[0036] The pressure-sensitive sensing system 20 transmits the internal cavity pressure information to the terminal PLC system. When the pressure in the tank is instantly greater than the safety factor required by the process design, the terminal PLC system receives the signal and feeds it back to the exhaust valve 15, causing the exhaust valve 15 to open and quickly release the pressure to prevent fire from causing equipment failure.

[0037] When a fire occurs and the molten metal 5 touches the thermal sensor 21 and the temperature exceeds 200°C, the thermal sensor 21 transmits the temperature information to the terminal PLC system and then feeds it back to the exhaust valve 15, causing the exhaust valve 15 to open and quickly release pressure to prevent equipment failure.

[0038] If no fault occurs, open the exhaust valve to vent the air, then open the upper tank, lift out the mold, and complete the casting.

[0039] In the control method of the present invention, the interface heat transfer coefficients at different height positions and thickest positions of the casting are calculated, and then a three-dimensional pouring system model is established using modeling software such as UG and Solid. The three-dimensional pouring system model includes the pouring system, cooling system, sand core and sand mold. Procast software pre-processing or Ideas is used for grid division. The grid size is adjusted according to the actual operation situation. The mold is preheated before pouring to ensure the stability of the temperature measurement system. After pouring starts, the original temperature data of different positions are recorded. After pouring is completed and completely solidified, the data is processed in Excel and imported. In the file suffixed with Pre-fuxum.dat, set the post-inverse operation in the pre-processing module of the Procast software to generate the Pre-fixid.dat file, then run the inverse operation of the Procast software, input the measured original data into the software readable file, and perform reverse solution. The thermocouple position must be accurately found in the grid, which should be consistent with the actual situation. This will provide a basis for subsequent products to use software to simulate the solidification process of castings, determine their solidification sequence, temperature field and final solidification area, thereby reducing the probability of defects in castings and maximizing the avoidance of equipment damage caused by fire during the casting process.

[0040] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A control method for a differential pressure casting mold filling monitoring and solidification parameter testing system, comprising the following steps: Differential pressure casting mold filling monitoring: During the differential pressure casting filling process, as the molten metal fills the mold from the bottom of the mold cavity along the pouring system from bottom to top, the molten metal contacts multiple thermocouples in sequence from bottom to top over time. The multi-channel temperature measuring instrument transmits the temperature signals of the thermocouples at different positions in the tank over time to the PLC system to generate a temperature curve; Differential pressure casting parameter design: Based on the temperature curve, the height difference ΔH of the different thermocouple settings is divided by the time difference ΔT of the thermocouple temperature change at different times to calculate the filling rate of the molten metal at different height interfaces. The pressure increase and exhaust rate of the differential pressure equipment are adjusted through the PLC system to make the filling rates of different height interfaces as close as possible; Solidification parameter monitoring: Based on the temperature curve, determine whether different positions of the casting can solidify as simultaneously as possible or solidify from top to bottom. If the above conditions cannot be met, adjust the cooling system to make different heights or thicker parts of the casting solidify as simultaneously as possible or solidify from top to bottom.

2. The control method of the differential pressure casting casting filling monitoring and solidification parameter testing system according to claim 1 is characterized in that: Also includes Pressure monitoring step: The pressure information of the inner cavity of the lower tank body is transmitted to the PLC system through the pressure-sensitive sensing system connected to the inner cavity of the lower tank body. When the pressure in the tank is instantaneously greater than the process set value, the PLC system receives the signal and feeds it back to the exhaust valve, causing the exhaust valve to open and quickly release pressure.

3. The control method of the differential pressure casting mold filling monitoring and solidification parameter testing system according to claim 2, characterized in that: Also includes Fire monitoring steps: When a fire occurs, the molten metal touches the thermistors evenly distributed around the bottom of the upper tank and the sealing surface of the middle partition. When the temperature is greater than 200°C, the thermistors transmit the temperature information to the PLC system and then feed it back to the exhaust valve, causing the exhaust valve to open and quickly release pressure.

4. The control method of the differential pressure casting casting filling monitoring and solidification parameter testing system according to claim 3 is characterized in that: The differential casting process also includes the following steps before filling the mold: Place the riser tube into the preset center hole position of the middle partition, insert it into the crucible to form a molten metal channel, move the upper tank body to the middle partition to form a sealed tank body, open the air inlet valve to inflate until the air pressure of the upper tank body and the lower tank body is balanced, open the exhaust valve connected to the upper tank body to exhaust and reduce pressure, and under the action of the pressure of the lower tank body, the molten metal inside the crucible rises along the riser tube and enters the casting cavity.

5. A differential pressure casting mold filling monitoring and solidification parameter testing system, characterized by: Applying the control method described in any one of claims 1 to 4 above, the differential pressure casting mold filling monitoring and solidification parameter testing system comprises: The lower tank body is installed on the cement foundation of the pit, and the lower tank body is used to install the crucible holding furnace filled with molten metal; An upper tank body is installed above the lower tank body, and the upper tank body is used to place the casting mold; A middle partition is installed between the lower tank body and the upper tank body, and the middle partition divides the upper tank body and the lower tank body into two independent sealed spaces through a rotary seal; at least one gas source, connected to the upper tank body and the lower tank body respectively through gas flow pipes; The riser pipe passes through the middle partition to introduce the molten metal in the crucible holding furnace into the casting mold: A temperature testing system includes thermocouples arranged at different heights in the upper tank body and a multi-channel thermometer connected to the thermocouples. The multi-channel thermometer detects and records the temperature signals of different positions in the upper tank body that change over time and transmits them to the PLC system to form a temperature curve. A pressure-sensitive sensing system connected to the inner cavity of the lower tank body, the pressure-sensitive sensing system transmits pressure information of the inner cavity of the lower tank body to the PLC system to determine the slope of the pressure change of the inner cavity to control the pressure change during the filling process of the differential pressure casting; Thermistors are evenly distributed around the bottom of the upper tank and the circumference of the sealing surface of the middle partition. The thermosensitive sensors transmit temperature information to the PLC system to control pressure relief when the temperature inside the upper tank is abnormal.

6. The differential pressure casting mold filling monitoring and solidification parameter testing system according to claim 5, characterized in that: The thermocouples are respectively arranged at the resin sand outer surface interface and the contact interface between the external chiller and the molten metal.

7. The differential pressure casting mold filling monitoring and solidification parameter testing system according to claim 5, characterized in that: The crucible holding furnace further comprises Refractory bricks, laid on the bottom of the lower tank; A main body support frame is arranged on the refractory bricks, and the main body support frame and the refractory bricks form a furnace cavity; A crucible is arranged on the inner cavity of the furnace, and the molten metal is placed inside the crucible; and a heat-insulating cover is arranged on the top of the crucible.

8. The differential pressure casting mold filling monitoring and solidification parameter testing system according to claim 5, characterized in that: The casting mold further comprises A sand box is provided on the middle partition plate, and the sand box is filled with resin sand and a cooling system; The sand core is arranged in the sand box, and the sand core is arranged according to the tooling and the chill.

9. The differential pressure casting mold filling monitoring and solidification parameter testing system according to claim 5, characterized in that: The temperature testing system further comprises A thermocouple protection sleeve is inserted into the molten metal through the heat-insulating cover.

10. The differential pressure casting mold filling monitoring and solidification parameter testing system according to claim 5, characterized in that: The differential pressure casting mold filling monitoring and solidification parameter testing system also includes a plurality of valve bodies, the valve bodies are connected to the inner cavity of the tank, and the valve bodies further include an air inlet valve, connected to the inner cavity of the lower tank body and the inner cavity of the upper tank body respectively; Exhaust valves are connected to the inner cavities of the lower tank body and the upper tank body respectively, and the exhaust valves are used to exhaust and release pressure after the pressure maintenance is completed; The gas intercommunication valve is connected to the lower tank body and the upper tank body respectively. The gas intercommunication valve ensures pressure balance between the two tank bodies during the inflation process: A safety valve is provided on the top of the upper tank body and is connected to the interior of the upper tank body. The safety valve is used to ensure that the pressure in the upper tank body does not exceed a safety threshold.

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