Engine throttle gradient cooling die casting method and system

Abstract

The present application belongs to the technical field of die casting process optimization, and relates to an engine throttle gradient cooling die casting method and system, which comprises: generating a comprehensive sensing data set; intelligently dividing a cooling area into a high-strength cooling zone, a transition compensation zone and a thermal maintenance zone according to the structure of the workpiece, and simultaneously generating a three-dimensional zoning atlas; applying air mist cooling to the high-strength cooling zone, injecting low-temperature medium into the transition compensation zone, adjusting the heat conduction assembly in the thermal maintenance zone, and generating cooling control parameters; detecting the deformation offset of the workpiece surface during the cooling process, combining a preset deformation threshold to generate a deformation correction instruction; simultaneously generating a deformation compensation feedback signal; verifying the internal density of the workpiece based on the solidification shrinkage pressure echo characteristics to generate a feeding judgment result; when the feeding judgment result fails, the molten metal self-feeding in the defect area is realized by directional regulation of the thermal field distribution. The present application solves the problem of lacking a cooperative analysis mechanism of pressure fluctuation and temperature gradient.

Description

Technical Field

[0001] This invention belongs to the technical field of die casting process optimization, and relates to a gradient cooling die casting method and system for engine throttle valves. Background Technology

[0002] In metal die casting, the cooling control of the die casting mold directly affects the workpiece forming quality and production efficiency. Traditional methods are insufficient to accurately address the differentiated cooling requirements of composite structures with thin and thick walls. In thin-walled areas, excessive heat dissipation can easily lead to premature solidification of the melt, resulting in insufficient filling; while in thick-walled areas, heat accumulation can cause internal defects such as shrinkage cavities and porosity. Especially in the production of complex structural parts, uneven temperature distribution in the cavity can exacerbate workpiece deformation, increasing manufacturing costs in subsequent finishing processes.

[0003] Existing technologies often employ a zoned cooling strategy, applying a fixed intensity of cooling medium to different areas of the mold through pre-set cooling channels. For example, increasing the flow rate of water cooling pipes in thin-walled areas and extending the holding time in thick-walled areas. This type of method relies on manual experience to set static parameters, and cannot respond in real time to the dynamic changes in melt flow and temperature field. Furthermore, the matching degree between the cooling medium's effective range and the cavity geometry is low, which can easily lead to localized overcooling or heat retention.

[0004] Based on the above problems, traditional cooling methods have significant limitations. They lack a collaborative analysis mechanism for pressure fluctuations and temperature gradients, resulting in insufficient accuracy in predicting internal defects, long process optimization cycles, and high costs. Summary of the Invention

[0005] In a first aspect, the present invention provides a gradient cooling die-casting method for engine throttle valves, employing the following technical solution:

[0006] The gradient cooling die-casting method for engine throttle valve includes the following steps:

[0007] S1. Obtain the temperature gradient change signal and pressure fluctuation characteristics at the end of the pouring channel, the cavity junction, and the transition zone between thin and thick structures in the die-casting mold, and generate a comprehensive sensor dataset.

[0008] S2. Based on the matching relationship between the temperature gradient change signal and the pressure fluctuation characteristics in the comprehensive sensor dataset, the cooling area of ​​the workpiece structure is intelligently divided into a high-intensity cooling zone, a transition compensation zone, and a heat maintenance zone, generating a three-dimensional partition map.

[0009] S3. Based on the three-dimensional partition map, the high-intensity cooling zone is subjected to mist cooling, the transition compensation zone is injected with low-temperature medium, and the heat maintenance zone is adjusted to adjust the heat conduction components to generate cooling control parameters.

[0010] S4. Detect the deformation offset of the workpiece surface during the cooling process, and generate a deformation correction command based on the preset deformation threshold.

[0011] S5. Trigger the compensation mechanism in the corresponding area according to the deformation correction command, and generate a deformation compensation feedback signal by adjusting the local thermal expansion of the die-casting mold and the thermal conductivity of the surface coating.

[0012] S6. Verify the internal density of the workpiece based on the solidification shrinkage pressure echo characteristics, and generate the shrinkage compensation judgment result;

[0013] S7. When the feeding determination result is not passed, the molten metal in the defect area is self-fed by directional control of the thermal field distribution.

[0014] A further aspect of this invention involves generating a comprehensive sensing dataset, comprising the following steps:

[0015] A first type of sensing device is arranged at the end of the pouring channel of the die casting mold, a second type of sensing device is arranged at the cavity junction of the die casting mold, and a third type of sensing device is arranged in the thin-thickness transition area of ​​the die casting mold.

[0016] When molten metal is injected into the die-casting mold, the first type of sensor monitors the temperature change at the flow front of the molten metal, the second type of sensor captures the temperature difference at different locations inside the cavity, and the third type of sensor simultaneously records the heat distribution in the transition zone between thin and thick structures.

[0017] The pressure wave characteristics generated when the flow of molten metal is obstructed are sensed through a pressure wave transmitter;

[0018] Pressure fluctuation characteristics refer to the shape of pressure peaks generated by changes in resistance during the filling process of molten metal;

[0019] A comprehensive sensor dataset is generated, which includes temperature gradient change signals and pressure fluctuation characteristics with spatial location coordinates.

[0020] A further aspect of the present invention generates a three-dimensional partition map, comprising the following steps:

[0021] The temperature gradient change signal is matched with the temperature difference curve of adjacent regions and the peak shape of pressure fluctuation characteristics; if the temperature drop rate of a specific thin-walled region is detected to rise synchronously with the pressure peak frequency, the region is determined to be a high-intensity cooling zone.

[0022] If the temperature maintenance time of the thick-walled region exceeds a multiple set for the adjacent region and is accompanied by a decrease in the amplitude of the pressure wave peak, the region is determined to be a heat maintenance zone.

[0023] The transition region located at the junction of thin and thick walls exhibits both asymmetric temperature distribution and intermittent pressure peak abrupt changes, and this region is determined to be a transition compensation zone.

[0024] The partitioning results are output as a 3D partition map through a visualization interface.

[0025] A further aspect of the present invention generates a three-dimensional partition map, comprising the following steps:

[0026] The temperature gradient change signal is matched with the temperature difference curve of adjacent regions and the peak shape of pressure fluctuation characteristics; if the temperature drop rate of a specific thin-walled region is detected to rise synchronously with the pressure peak frequency, the region is determined to be a high-intensity cooling zone.

[0027] If the temperature maintenance time of the thick-walled region exceeds a multiple set for the adjacent region and is accompanied by a decrease in the amplitude of the pressure wave peak, the region is determined to be a heat maintenance zone.

[0028] The transition region located at the junction of thin and thick walls exhibits both asymmetric temperature distribution and intermittent pressure peak abrupt changes, and this region is determined to be a transition compensation zone.

[0029] The partitioning results are output as a 3D partition map through a visualization interface.

[0030] A further aspect of the present invention involves generating a deformation correction instruction based on a preset deformation threshold, comprising the following steps:

[0031] The die-casting mold cavity surface is provided with multiple sets of laser ranging arrays. Each array contains laser emitters and receivers arranged in a cross shape. By calculating the change in optical path difference between the emitter and receiver, the three-dimensional offset of each measurement point on the workpiece surface is obtained.

[0032] Correlate the characteristics of pressure fluctuations and establish a correlation model between deformation offset and internal stress distribution;

[0033] The condition for generating a deformation correction command is that the cumulative offset value exceeds the allowable value of the material's thermal expansion coefficient. When this condition is met, a deformation correction command containing the coordinates of the deformation point, the offset direction, and the amount of compensation required is generated.

[0034] A further aspect of this invention involves establishing an association model, including the following steps:

[0035] By multiplying the peak attenuation rate of the pressure wave transmitter with the offset growth rate at the corresponding position, it can be determined whether the deformation is caused by internal shrinkage or surface stress.

[0036] The threshold Q is determined by comparing destructive and non-destructive testing experiments. If the product value is greater than the threshold Q, it corresponds to internal shrinkage cavity; if the product value is less than the threshold Q, it corresponds to surface stress concentration.

[0037] A further aspect of the present invention generates a deformation compensation feedback signal, comprising the following steps:

[0038] When the position coordinates contained in the deformation correction command are identified as a high-intensity cooling zone or a transition compensation zone, the control terminal sends a current pulse signal to the aluminum alloy insert in the corresponding area. The local temperature of the aluminum alloy insert is increased by resistance heating, and the volume of the contact surface of the die-casting mold is increased by utilizing the thermal expansion property of the metal material.

[0039] A high-voltage electric field is applied to the surface of the die-casting mold corresponding to the heat maintenance zone, and the thermal conductivity is adjusted by changing the arrangement direction of alumina crystals in the nano-coating.

[0040] The expansion of the aluminum alloy insert is adjusted according to the direction and magnitude of the deformation offset, while the change in the thermal conductivity of the nano-coating is dynamically matched with the temperature stress distribution.

[0041] A further aspect of the present invention generates a compensation determination result, comprising the following steps:

[0042] At the end of the pressure holding stage of the die casting mold, the pressure wave transmitters are used to collect the pressure wave signal generated by solidification shrinkage. By analyzing the attenuation rate and frequency characteristics of the pressure wave signal, the distribution of internal shrinkage defects is determined.

[0043] If the ratio of the peak attenuation amplitude of the pressure fluctuation signal to that of the standard sample is lower than the set critical value, it is determined that the area needs to be replenished with molten metal to eliminate shrinkage cavities; otherwise, the workpiece is confirmed to have reached the predetermined density standard and mold opening is allowed.

[0044] A further aspect of the present invention achieves self-feeding of molten metal in defect areas by directional control of the thermal field distribution, comprising the following steps:

[0045] After the area where the peak attenuation of the pressure fluctuation signal is lower than the set critical value is marked as a defect area, the control terminal reactivates the heat maintenance control device corresponding to the area, so that a local high temperature zone is formed at its front end to soften the solidified shell.

[0046] Increase the pressure of the hydraulic system on the back of the die-casting mold to force the residual molten metal to flow along the heat flow direction guided by the heat-conducting rod to fill the shrinkage cavity; at the same time, adjust the thermal conductivity of the nano-coating to the minimum value to slow down the heat loss on the feeding path.

[0047] Secondly, this invention provides an engine throttle valve gradient cooling die-casting system, which adopts the following technical solution:

[0048] The engine throttle valve gradient cooling die-casting system includes the following modules:

[0049] The data acquisition module is used to acquire temperature gradient change signals and pressure fluctuation characteristics at the end of the pouring channel, the cavity junction and the transition zone between thin and thick structures in the die-casting mold, so as to generate a comprehensive sensor dataset.

[0050] The region division module divides the region into high-intensity cooling zone, transition compensation zone, and heat maintenance zone based on the matching relationship between temperature gradient change signal and pressure fluctuation characteristics in the comprehensive sensor dataset, and generates a three-dimensional partition map.

[0051] The cooling control module is used to apply aerosol cooling in the high-intensity cooling zone, inject low-temperature medium in the transition compensation zone, and adjust the heat conduction components in the heat maintenance zone.

[0052] The deformation detection module is used to detect the deformation offset of the workpiece surface during the cooling process and generate deformation correction instructions in combination with the preset deformation threshold.

[0053] The compensation execution module triggers the compensation mechanism in the corresponding area according to the deformation correction command, and generates a deformation compensation feedback signal by adjusting the local thermal expansion of the die-casting mold and the thermal conductivity of the surface coating.

[0054] The density verification module verifies the internal density of the workpiece based on the solidification shrinkage pressure echo characteristics and generates a shrinkage judgment result.

[0055] The feeding control module, when the feeding determination result is not passed, achieves self-feeding of molten metal in the defect area by directional control of the thermal field distribution.

[0056] In summary, the present invention has the following beneficial technical effects:

[0057] 1. Through the deep integration of multi-dimensional sensing and dynamic control technologies, the quality control level of the die-casting process has been significantly improved. Based on the collaborative analysis mechanism of temperature gradient and pressure fluctuation, intelligent division and precise matching of mold cooling zones have been achieved, enabling simultaneous optimization of the rapid solidification of thin-walled structures and the heat retention problem in thick-walled areas;

[0058] 2. The phased closed-loop control system significantly enhances process stability. From dynamic monitoring during the melt filling stage to directional control during the solidification and feeding stage, a full-process adaptive control chain is formed, especially with the synergistic effect of pulse cooling and gradient heat conduction in the transition compensation zone and the heat maintenance zone.

[0059] 3. The intelligent decision-making system based on multiphysics coupling enables dynamic optimization of process parameters. By performing deep learning on the thermodynamic properties of materials, equipment response parameters, and real-time sensor data, the system can autonomously adjust the cooling intensity and the timing of feed compensation. Attached Figure Description

[0060] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings are used to provide a further understanding of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 A flowchart illustrating the gradient cooling die-casting method for engine throttle valves is disclosed.

[0062] Figure 2 A schematic diagram of the engine throttle body gradient cooling die-casting system is disclosed. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] The following is in conjunction with the appendix Figures 1-2 A preferred description of the present invention is provided below.

[0065] See attached document Figure 1 This invention proposes a gradient cooling die-casting method for engine throttle valves, comprising the following steps:

[0066] S1. Obtain the temperature gradient change signal and pressure fluctuation characteristics at the end of the pouring channel, the cavity junction, and the transition zone between thin and thick structures in the die-casting mold, and generate a comprehensive sensor dataset.

[0067] S2. Based on the matching relationship between the temperature gradient change signal and the pressure fluctuation characteristics in the comprehensive sensor dataset, the cooling area of ​​the workpiece structure is intelligently divided into a high-intensity cooling zone, a transition compensation zone, and a heat maintenance zone, generating a three-dimensional partition map.

[0068] S3. Based on the three-dimensional partition map, the high-intensity cooling zone is subjected to mist cooling, the transition compensation zone is injected with low-temperature medium, and the heat maintenance zone is adjusted to adjust the heat conduction components to generate cooling control parameters.

[0069] S4. Detect the deformation offset of the workpiece surface during the cooling process, and generate a deformation correction command based on the preset deformation threshold.

[0070] S5. Trigger the compensation mechanism in the corresponding area according to the deformation correction command, and generate a deformation compensation feedback signal by adjusting the local thermal expansion of the die-casting mold and the thermal conductivity of the surface coating.

[0071] S6. Verify the internal density of the workpiece based on the solidification shrinkage pressure echo characteristics, and generate the shrinkage compensation judgment result;

[0072] S7. When the feeding determination result is not passed, the molten metal in the defect area is self-fed by directional control of the thermal field distribution.

[0073] In one embodiment of the present invention, step S1 includes the following steps:

[0074] Multiple sets of sensors deployed at the end of the pouring channel, the junction of the cavity, and the transition zone between thin and thick structures of the die-casting mold are used to collect temperature gradient change signals and pressure fluctuation characteristics in real time. The pressure fluctuation characteristics refer to the shape of the pressure wave peak generated by the change of resistance during the filling process of molten metal.

[0075] Specifically, a first-type sensing device is arranged at the end of the pouring channel of the die-casting mold, a second-type sensing device is arranged at the cavity interface of the die-casting mold, and a third-type sensing device is arranged in the transition zone between thin and thick structures of the die-casting mold. When molten metal is injected into the die-casting mold, the first-type sensing device is an infrared temperature sensor used to monitor the temperature change at the molten metal flow front; the second-type sensing device is a thermocouple array used to capture the temperature difference at different locations inside the cavity; and the third-type sensing device is a heat flux density sensor used to simultaneously record the heat distribution in the transition zone between thin and thick structures. A pressure wave transmitter is embedded at a specific depth in the wall of the die-casting mold, with its detection end face in direct contact with the molten metal, used to sense the pressure fluctuation characteristics generated when the molten metal flow is obstructed. The output signals of multiple sets of sensing devices are transmitted to a signal processing terminal through shielded cables to form a comprehensive sensing dataset containing temperature gradient change signals and pressure fluctuation characteristics, including spatial location coordinates.

[0076] Among them, the temperature gradient change signal refers to the temperature difference change curve of adjacent areas continuously recorded over time. The heat accumulation trend is determined by comparing the differences in the rate of temperature change at different locations. Multiple sensing devices refer to a combination device containing at least three sets of sensors with different functions. Each set of sensors performs a specific parameter acquisition task based on its installation location. Pressure fluctuation characteristics refer to the shape of pressure peaks generated during the flow of molten metal due to obstruction. Specifically, it is manifested by a combination of peak number, amplitude, and interval time, used to characterize the density of the molten metal filling.

[0077] For example, a first type of sensing device is arranged at the end of the gating channel of the die-casting mold, including a ring-shaped distribution of temperature probes that collect temperature values ​​at eight equally divided points along the circumference. A second type of sensing device is arranged at the cavity interface of the die-casting mold, with the probe tip of the second type of sensing device approximately 1.5 mm from the cavity surface to avoid flow erosion as much as possible. A third type of sensing device is arranged at a 45-degree angle in the thin-thickness transition zone of the die-casting mold, so that the detection direction of the third type of sensing device intersects with the molten metal flow path.

[0078] The pressure wave transducer is embedded at a specific depth in the wall of the die-casting mold. The detection end face of the pressure wave transducer is connected to the cavity of the die-casting mold through a 2mm diameter pressure guide hole. Multiple sensor devices are designed for high temperature resistance; for example, the surface of the sensor device is covered with a 0.5mm silicon nitride coating. The pressure guide hole employs a self-cleaning mechanism; for example, the detection surface of the pressure wave transducer is covered with a 0.3mm thick zirconia ceramic layer, and the pressure guide hole is backflushed with a 0.2MPa nitrogen pulse every 5 seconds.

[0079] When molten metal is injected into the die-casting mold, the first type of sensing device, the second type of sensing device, and the third type of sensing device collect data at a frequency of 5 times per second. The signal processing terminal performs correlation analysis on the temperature drop rate at the end of the pouring channel, the extreme temperature difference at the cavity interface, the heat flow direction in the transition zone between thin and thick structures, and the peak frequency of the pressure wave conductor to generate a dynamic temperature gradient map and pressure fluctuation characteristic spectrum.

[0080] In one embodiment of the present invention, step S2 includes the following steps:

[0081] Based on the correspondence between temperature gradient change signals and pressure fluctuation characteristics, the cooling zones of the workpiece structure are intelligently divided into three areas: a high-intensity cooling zone, a transition compensation zone, and a heat maintenance zone. The high-intensity cooling zone corresponds to the thin-walled structural portion, the transition compensation zone corresponds to the transition area located at the junction of the thin and thick walls, and the heat maintenance zone corresponds to the thick-walled boss portion.

[0082] Specifically, the temperature difference curves of adjacent regions in the temperature gradient change signal are matched with the peak shapes in the pressure fluctuation characteristics. Based on extensive experimental data verifying the matching relationship between temperature and pressure signals, it can be determined that: if the temperature decrease rate of a specific thin-walled region increases synchronously with the pressure peak frequency, that region is identified as a high-intensity cooling zone. If the temperature maintenance duration of a thick-walled region exceeds 1.5 times that of adjacent regions and is accompanied by a pressure peak amplitude attenuation characteristic, that region is identified as a heat-maintaining zone. The transition region located at the junction of thin and thick walls, exhibiting both asymmetric temperature distribution and intermittent pressure peak abrupt changes, is identified as a transition compensation zone. The partitioning results are output as a three-dimensional partition map through a visualization interface, with the partition boundaries dynamically determined based on the product of the temperature fluctuation amplitude and the pressure signal characteristic intensity.

[0083] Intelligent cooling zone partitioning refers to the process of automatically generating partition boundaries based on physical signal characteristics. Its core lies in identifying the difference in heat dissipation patterns between thin-walled areas and thick-walled areas, satisfying the following formula:

[0084]

[0085] in, This is the coefficient for determining the cooling zone. The rate of temperature decrease is obtained through differential calculation using a temperature sensor. The initial temperature of the molten metal is set through process parameters. The peak frequency of the pressure wave is obtained from FFT analysis of the pressure wave transmitter. The maximum allowable frequency is set based on the structural strength of the die-casting mold.

[0086] Based on experimental data and expert experience, the threshold value for the hot zone, determined by the cooling zone judgment coefficient, is set as follows: The threshold value for the cold zone in the cooling zone determination coefficient is: ; It was determined to be a high-intensity cooling zone at that time. When it is determined to be a transition compensation zone, When it is determined to be a heat maintenance zone.

[0087] A three-dimensional zoning map is a dynamic distribution map that uses the coordinate system of the die-casting mold cavity as a reference and marks three types of regions with different colors, red, blue and yellow, respectively. You can view the corresponding signal characteristic parameters by clicking on the coordinate points.

[0088] For example, the temperature gradient change signal generated in step S1 is superimposed on the three-dimensional model of the die-casting mold. It is observed that the temperature curve of a thin-walled region drops by 200°C within 0.8 seconds (corresponding to a pressure peak frequency of 12 times / second), and this region is highlighted in red as a high-intensity cooling zone. It is detected that the temperature maintenance curve of the thick-walled boss region is flat (fluctuation less than 20°C within 5 seconds) and the pressure peak amplitude decays to 30% of the initial value, and this region is highlighted in blue as a heat maintenance zone. The band-shaped region between the two is highlighted in yellow as a transition compensation zone because the temperature change rate is between the two and the pressure peaks show a pulse characteristic with an interval of 0.5 seconds.

[0089] In one embodiment of the present invention, step S3 includes the following steps:

[0090] Each zone is divided into different cooling control zones. The high-intensity cooling zone applies aerosol cooling (gas + trace amount of coolant) to form a rapid cooling layer. The transition compensation zone is intermittently injected with a low-temperature medium (such as ethylene glycol solution) to generate a pulse cooling effect. The heat maintenance zone actively adjusts the cooling rate through heat conduction components.

[0091] Specifically, the high-intensity cooling zone features a ring-shaped array of atomizing nozzles installed on the outer surface of the die-casting mold. High-pressure gas decomposes a small amount of coolant into micron-sized droplets, covering the area and forming a uniform, rapidly cooling layer. The transition compensation zone has a cryogenic medium channel internally embedded with a solenoid valve, intermittently spraying cryogenic medium onto the cavity surface through periodic opening and closing, creating alternating thermal shock effects. The heat maintenance zone has an adjustable heat-conducting rod assembly made of highly thermally conductive material mounted on the back of the die-casting mold. The heat transfer rate of the heat-conducting rods is dynamically adjusted through the coordination of electric heating elements and circulating cooling pipes. The cooling operation is synchronized and coordinated by a central controller to ensure that the cooling rate of the three zones matches the heat capacity of the workpiece structure.

[0092] The atomizing nozzle assembly refers to a gas-liquid mixing and spraying device arranged in a ring array, with a gradually narrowing outlet cross-section to enhance the atomization effect. The rapid cooling layer refers to the transient high-heat exchange area formed on the surface of the die-casting mold through atomized water cooling; its coverage area completely overlaps with the three-dimensional zoning map of the high-intensity cooling zone. The cryogenic medium channel is a double-cavity pipe with an internal insulation layer. The outer cavity of the cryogenic medium channel is filled with coolant, while the inner cavity's spray interval is controlled by a solenoid valve.

[0093] The pulse cooling effect is manifested as the alternating effect of rapid heat absorption during medium injection and natural temperature recovery when injection stops, similar to applying hot and cold towels alternately to relieve stress concentration.

[0094] The adjustable heat-conducting rod assembly contains axially stacked heat-conducting units, each of which adjusts its heat conduction direction and rate through an independent temperature control module;

[0095] The heat conduction rate of the heat-conducting rod is dynamically adjusted, and the electric heating power is adjusted according to real-time temperature feedback.

[0096] For example, based on the three-dimensional zoning map generated in step S2, eight sets of atomizing nozzles are installed on the outer ring of the high-intensity cooling zone. Each set of nozzles is spaced 15mm apart and tilted at a 30-degree angle. When the controller receives a signal indicating that the temperature in this area exceeds the limit, it initiates the mixed spraying of compressed air and a small amount of coolant, with the atomized droplet diameter controlled within the range of 50-80μm. The die-casting mold sidewall in the transition compensation zone has 12 low-temperature medium channels, each opening once every 5 seconds, with each spray lasting 0.3 seconds. This causes the die-casting mold surface temperature to fluctuate periodically within a range of ±25℃, determined based on the material test data of the die-casting mold. The heat-conducting rod group in the heat maintenance zone consists of 36 copper-tungsten alloy rods. The electric heating coils inside the copper-tungsten alloy rods are activated, dynamically adjusting the heat conduction rate of the heat-conducting rods. Simultaneously, circulating water cooling is initiated in adjacent areas to dissipate redundant heat.

[0097] In one embodiment of the present invention, step S4 includes the following steps:

[0098] The deformation offset of the workpiece surface during the cooling process is detected, and local deformations exceeding the allowable range are dynamically corrected, generating deformation correction instructions that include position coordinates and compensation amounts.

[0099] Specifically, multiple laser ranging arrays are arranged on the surface of the die-casting mold cavity. Each array contains laser emitters and receivers arranged in a cross shape. When the workpiece deforms during the cooling process, the reflection angle of the laser beam on the workpiece surface changes accordingly. By calculating the change in the optical path difference between the emitter and receiver, the three-dimensional offset of each measurement point on the workpiece surface is obtained.

[0100] Based on the solidification and shrinkage characteristics of molten metal recorded by the pressure wave transmitter in step S1, a correlation model between deformation offset and internal stress distribution is established. When the cumulative offset value of a certain region exceeds the allowable value of the thermal expansion coefficient of the material in that region, a deformation correction command containing the coordinates of the deformation point, the offset direction, and the compensation requirement is generated.

[0101] The three-dimensional offset includes displacement components along the X, Y, and Z axes, and the direction of their composite vector reflects the deformation trend. The change in optical path difference refers to the difference in the round-trip path length of the laser beam caused by the workpiece deformation, which is calculated using the phase interferometry method.

[0102] A laser ranging array is a measurement network consisting of at least four sets of laser transceivers, whose installation positions are aligned with the boundaries of the cooling area defined in step S2.

[0103] The correlation model maps deformed surface data to internal pressure characteristics. By multiplying the peak attenuation rate of the pressure wave conductor with the corresponding offset growth rate, it determines whether the deformation originates from internal shrinkage or surface stress. A threshold Q is determined by comparing destructive and non-destructive testing experiments. If the product value is greater than the threshold Q, it corresponds to internal shrinkage; if the product value is less than the threshold Q, it corresponds to surface stress concentration.

[0104] The allowable value of the material's coefficient of thermal expansion is calculated by multiplying the material's coefficient of thermal expansion by the workpiece size.

[0105] For example, during the implementation of the transition compensation zone in a die-casting mold, the laser ranging array detects that the Z-axis offset at a certain interface measurement point increases by 0.05mm cumulatively within 3 seconds. Simultaneously, the pressure wave transmitter records a 40% decrease in the peak amplitude of the pressure wave at that location. Based on the correlation model, the product of these two values ​​is less than a threshold, indicating that the deformation is caused by the transmission of shrinkage stress in the thick-walled area. A deformation correction command is then generated: a heating command is sent to the aluminum alloy inserts within a 10mm radius around the point coordinate, causing their expansion to offset the workpiece deformation. During the correction process, the laser ranging array continuously feeds back the offset attenuation curve until the value returns to the allowable range.

[0106] In one embodiment of the present invention, step S5 includes the following steps:

[0107] The compensation mechanism in the corresponding area is triggered according to the deformation correction command. The workpiece deformation is offset in real time by changing the thermal expansion of the die-casting mold contact surface. At the same time, the thermal conductivity of the die-casting mold surface coating is adjusted to balance the thermal stress. Changing the thermal expansion of the die-casting mold contact surface means using the thermal expansion characteristics of metal materials to accurately control the local volume change of the die-casting mold.

[0108] Specifically, when the position coordinates included in the deformation correction command are identified as a high-intensity cooling zone or a transition compensation zone, the control terminal sends a current pulse signal to the aluminum alloy insert in the corresponding area. This raises the local temperature of the aluminum alloy insert through resistance heating, utilizing the thermal expansion property of metal materials to increase the volume of the die-casting mold contact surface. A high-voltage electric field is applied to the surface of the die-casting mold corresponding to the heat maintenance zone, adjusting its thermal conductivity by changing the alignment direction of the alumina crystals in the nano-coating. The expansion amount of the aluminum alloy insert is proportionally adjusted according to the direction and magnitude of the deformation offset. The change in the thermal conductivity of the nano-coating is dynamically matched to the temperature stress distribution.

[0109] The compensation mechanism is a composite device consisting of an aluminum alloy insert, a resistance heating element, and a high-voltage electric field generator. Its function is to counteract workpiece deformation through changes in physical properties. The current pulse signal is a square wave electrical signal with adjustable width, and its amplitude and duration are calculated from the compensation requirement in the deformation correction command.

[0110] Resistance heating utilizes the Joule heating effect generated when an electric current flows through a tungsten wire coil embedded within an aluminum alloy insert. The heating power is proportional to the product of the tungsten wire coil's resistance and the square of the current. The high-voltage electric field is the potential difference created by a DC voltage applied between two electrodes, used to drive the alumina crystals in the nano-coating to align oriented along the direction of the electric field. Adjusting the thermal conductivity refers to the physical process of controlling the heat transfer rate by changing the crystal arrangement density.

[0111] In one embodiment of the present invention, step S6 includes the following steps:

[0112] Before mold opening, verify whether the internal density of the workpiece meets the predetermined standard, and determine whether the secondary feeding conditions are met based on the pressure echo characteristics generated by solidification shrinkage.

[0113] Specifically, at the end of the pressure holding stage of the die-casting mold, the pressure wave transmitter arranged in step S1 is used to collect the pressure fluctuation signal generated by solidification shrinkage. By analyzing the attenuation rate and frequency characteristics of the pressure fluctuation signal, the distribution of internal shrinkage defects is determined. If the ratio of the peak attenuation amplitude of the pressure fluctuation signal to that of the standard sample is lower than the set critical value, it is determined that the area needs to be replenished with molten metal to eliminate shrinkage cavities; otherwise, the workpiece is confirmed to have reached the predetermined density standard and mold opening is allowed. The above determination process, combined with the temperature field distribution formed by gradient cooling in step S3, prioritizes the verification of the boundary between the thick-walled area and the transition area.

[0114] The pressure fluctuation signal refers to the pressure fluctuation characteristics generated within a closed cavity during the solidification and shrinkage of molten metal. Its attenuation rate is inversely proportional to the internal porosity. The peak attenuation amplitude is the percentage difference between the maximum peak amplitude recorded by the pressure wave transmitter and the reference amplitude during the initial filling stage. The standard sample refers to the set of pressure echo characteristic data corresponding to a workpiece that has been pre-confirmed to be defect-free through X-ray inspection. The critical value is set based on the relationship curve between the material shrinkage rate and the cooling rate. Replenishing molten metal refers to the process of allowing residual molten metal to reflow and fill the pores through localized heating.

[0115] For example, during the verification of the thick-walled boss area, the pressure wave transmitter recorded that the pressure echo peak value decreased from 12MPa in the initial filling stage to 3.6MPa, with an attenuation of 70%. The critical value set for this area is that the attenuation does not exceed 65%, indicating that there is a risk of shrinkage cavities. The adjustable heat-conducting rod group in the heat maintenance zone is activated to raise the temperature of the die-casting mold in the corresponding area to the semi-solid range of the material. After the qualified standard is met, the pressure holding state is released.

[0116] In one embodiment of the present invention, step S7 includes the following steps:

[0117] When step S6 determines that the internal density of the workpiece does not meet the standard, the molten metal in the defect area is self-compensated by directional control of the thermal field distribution.

[0118] Specifically, after a region where the peak attenuation of the pressure fluctuation signal is below the critical value is marked as a defect area, the control terminal reactivates the corresponding heat maintenance control device in that region. This increases the heating power of the adjustable heat-conducting rod assembly to the preset feeding mode, creating a localized high-temperature zone at its front end to soften the solidified shell. The hydraulic system pressure on the back of the die-casting mold is increased, forcing residual molten metal to flow along the heat flow direction guided by the heat-conducting rods to fill the shrinkage cavity. Simultaneously, the thermal conductivity of the nano-coating is adjusted to its minimum value to slow heat loss along the feeding path. The feeding amount is adjusted proportionally based on the difference between the pressure echo attenuation amplitude in the defect area and the critical value until the pressure transmission signal recovers to the acceptable range.

[0119] The heat maintenance control device is an integrated system comprising an adjustable heat-conducting rod assembly, a hydraulic booster unit, and a coating control module. Its function is to reconstruct local thermodynamic conditions to drive the flow of molten metal. The local high-temperature zone is a temperature gradient field formed by resistance heating at the front end of the heat-conducting rods, with its temperature value between the solidus and liquidus lines of the material. The softening of the solidified shell is the physical process by which heat from the high-temperature zone is conducted to the workpiece surface, allowing the surface solidified metal to regain its plastic deformation capacity.

[0120] The direction of heat flow is determined by the temperature gradient distribution of the heat-conducting rod assembly, with the path from the high-temperature end to the defect area forming the driving force for molten metal flow. The compensation amount is the product of the pressure applied by the hydraulic system and the duration of compensation, dynamically adjusted based on the recovery rate of the pressure fluctuation signal.

[0121] For example, when the pressure echo attenuation at the interface of the thick-walled boss is 72% (the critical value is 65%), the feeding process is initiated:

[0122] The heating power of the corresponding heat-conducting rod assembly was increased to 8kW, creating a 420℃ high-temperature zone with a diameter of 5mm at its front end. Simultaneously, the hydraulic pressure was increased from 80MPa to 110MPa, and after 3 seconds, the pressure echo peak rose back to 4.8MPa, with the attenuation rate decreasing to 60%. The thermal conductivity of the nano-coating was locked at 70% of its initial value to reduce heat loss and ensure that the molten metal flow lasted for 5 seconds. Self-compensation of the molten metal in the defect area was achieved by directional control of the thermal field distribution.

[0123] See appendix Figure 2 The present invention also proposes an engine throttle valve gradient cooling die-casting system, comprising the following modules:

[0124] The data acquisition module is used to acquire temperature gradient change signals and pressure fluctuation characteristics at the end of the pouring channel, the cavity junction and the transition zone between thin and thick structures in the die-casting mold, so as to generate a comprehensive sensor dataset.

[0125] The region division module divides the region into high-intensity cooling zone, transition compensation zone, and heat maintenance zone based on the matching relationship between temperature gradient change signal and pressure fluctuation characteristics in the comprehensive sensor dataset, and generates a three-dimensional partition map.

[0126] The cooling control module is used to apply aerosol cooling in the high-intensity cooling zone, inject low-temperature medium in the transition compensation zone, and adjust the heat conduction components in the heat maintenance zone.

[0127] The deformation detection module is used to detect the deformation offset of the workpiece surface during the cooling process and generate deformation correction instructions in combination with the preset deformation threshold.

[0128] The compensation execution module triggers the compensation mechanism in the corresponding area according to the deformation correction command, and generates a deformation compensation feedback signal by adjusting the local thermal expansion of the die-casting mold and the thermal conductivity of the surface coating.

[0129] The density verification module verifies the internal density of the workpiece based on the solidification shrinkage pressure echo characteristics and generates a shrinkage judgment result.

[0130] The feeding control module, when the feeding determination result is not passed, achieves self-feeding of molten metal in the defect area by directional control of the thermal field distribution.

[0131] It should be noted that the formulas described above, through the principle of dimensional consistency and mathematical standardization methods (such as normalization, dimensionless parameter conversion, or unit system unification), can translate physical quantities with different properties into unitless standard values ​​or superimposed parameters of the same dimension. This eliminates the interference of different dimensions on the computational logic, allowing the formulas to retain the original data distribution characteristics while possessing mathematical rationality and adaptability to objective laws. The descriptions are merely exemplary embodiments of the present invention and should not be construed as limiting the scope of the invention.

[0132] Each of the modules can be implemented in whole or in part through software, hardware, or a combination thereof. It supports hardware embedded in or independent of the processor in the computer device, and also supports software stored in the memory of the computer device, so that the processor can call and execute the operations corresponding to each of the above modules.

[0133] It should be noted that the human information (including but not limited to human device information and personal information) and data (including but not limited to data used for analysis, data stored and data displayed) involved in this invention are all information and data authorized by the human body or fully authorized by all parties. The collection, use and processing of related data require relevant legal standards.

[0134] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A gradient cooling die-casting method for engine throttle valve, characterized in that, Includes the following steps: S1. Obtain the temperature gradient change signal and pressure fluctuation characteristics at the end of the pouring channel, the cavity junction, and the transition zone between thin and thick structures in the die-casting mold, and generate a comprehensive sensor dataset. S2. Based on the matching relationship between the temperature gradient change signal and the pressure fluctuation characteristics in the comprehensive sensor dataset, the cooling area of ​​the workpiece structure is intelligently divided into a high-intensity cooling zone, a transition compensation zone, and a heat maintenance zone, generating a three-dimensional partition map. The temperature gradient change signal is matched with the temperature difference curve of adjacent regions and the peak shape of pressure fluctuation characteristics; if the temperature drop rate of a specific thin-walled region is detected to rise synchronously with the pressure peak frequency, the region is determined to be a high-intensity cooling zone. If the temperature maintenance time of the thick-walled region exceeds a multiple set for the adjacent region and is accompanied by a decrease in the amplitude of the pressure wave peak, the region is determined to be a heat maintenance zone. The transition region located at the junction of thin and thick walls exhibits both asymmetric temperature distribution and intermittent pressure peak abrupt changes, and this region is determined to be a transition compensation zone. The partitioning results are output as a 3D partition map through a visualization interface; S3. Based on the three-dimensional partition map, the high-intensity cooling zone is subjected to mist cooling, the transition compensation zone is injected with low-temperature medium, and the heat maintenance zone is adjusted to adjust the heat conduction components to generate cooling control parameters. S4. Detect the deformation offset of the workpiece surface during the cooling process, and generate a deformation correction command based on the preset deformation threshold. S5. Trigger the compensation mechanism in the corresponding area according to the deformation correction command, and generate a deformation compensation feedback signal by adjusting the local thermal expansion of the die-casting mold and the thermal conductivity of the surface coating. S6. Verify the internal density of the workpiece based on the solidification shrinkage pressure echo characteristics, and generate the shrinkage compensation judgment result; S7. When the feeding determination result is not passed, the molten metal in the defect area is self-fed by directional control of the thermal field distribution.

2. The engine throttle valve gradient cooling die-casting method according to claim 1, characterized in that, Generating a comprehensive sensor dataset includes the following steps: A first type of sensing device is arranged at the end of the pouring channel of the die casting mold, a second type of sensing device is arranged at the cavity junction of the die casting mold, and a third type of sensing device is arranged in the thin-thickness transition area of ​​the die casting mold. When molten metal is injected into the die-casting mold, the first type of sensor monitors the temperature change at the flow front of the molten metal, the second type of sensor captures the temperature difference at different locations inside the cavity, and the third type of sensor simultaneously records the heat distribution in the transition zone between thin and thick structures. The pressure wave characteristics generated when the flow of molten metal is obstructed are sensed through a pressure wave transmitter; Pressure fluctuation characteristics refer to the shape of pressure peaks generated by changes in resistance during the filling process of molten metal; A comprehensive sensor dataset is generated, which includes temperature gradient change signals and pressure fluctuation characteristics with spatial location coordinates.

3. The engine throttle valve gradient cooling die-casting method according to claim 1, characterized in that, Generating cooling control parameters includes the following steps: The high-intensity cooling zone uses high-pressure gas to decompose a small amount of coolant into micron-sized droplets and cover the area, forming a uniform and rapid cooling layer; the die-casting mold in the transition compensation zone is equipped with a low-temperature medium channel controlled by an electromagnetic valve, which intermittently sprays the low-temperature medium onto the surface of the cavity in a periodic opening and closing manner. The heat maintenance zone is assembled on the back of the die-casting mold, and consists of an adjustable heat-conducting rod assembly made of a high thermal conductivity material. The heat conduction rate of the heat-conducting rod is dynamically adjusted through the cooperation of an electric heating element and a circulating cooling pipeline.

4. The engine throttle valve gradient cooling die-casting method according to claim 3, characterized in that, The deformation correction instruction is generated by combining a preset deformation threshold, including the following steps: The die-casting mold cavity surface is provided with multiple sets of laser ranging arrays. Each array contains laser emitters and receivers arranged in a cross shape. By calculating the change in optical path difference between the emitter and receiver, the three-dimensional offset of each measurement point on the workpiece surface is obtained. Correlate the characteristics of pressure fluctuations and establish a correlation model between deformation offset and internal stress distribution; The condition for generating a deformation correction command is that the cumulative offset value exceeds the allowable value of the material's thermal expansion coefficient. When this condition is met, a deformation correction command containing the coordinates of the deformation point, the offset direction, and the amount of compensation required is generated.

5. The engine throttle valve gradient cooling die-casting method according to claim 4, characterized in that, Establishing a correlation model between deformation offset and internal stress distribution includes the following steps: By multiplying the peak attenuation rate of the pressure wave transmitter with the offset growth rate at the corresponding position, it can be determined whether the deformation is caused by internal shrinkage or surface stress. The threshold Q is determined by comparing destructive and non-destructive testing experiments. If the product value is greater than the threshold Q, it corresponds to internal shrinkage cavity; if the product value is less than the threshold Q, it corresponds to surface stress concentration.

6. The engine throttle valve gradient cooling die-casting method according to claim 4, characterized in that, Generating a deformation compensation feedback signal includes the following steps: When the position coordinates contained in the deformation correction command are identified as a high-intensity cooling zone or a transition compensation zone, the control terminal sends a current pulse signal to the aluminum alloy insert in the corresponding area. The local temperature of the aluminum alloy insert is increased by resistance heating, and the volume of the contact surface of the die-casting mold is increased by utilizing the thermal expansion property of the metal material. A high-voltage electric field is applied to the surface of the die-casting mold corresponding to the heat maintenance zone, and the thermal conductivity is adjusted by changing the arrangement direction of alumina crystals in the nano-coating. The expansion of the aluminum alloy insert is adjusted according to the direction and magnitude of the deformation offset, while the change in the thermal conductivity of the nano-coating is dynamically matched with the temperature stress distribution.

7. The engine throttle valve gradient cooling die-casting method according to claim 6, characterized in that, Generating the compensation determination result includes the following steps: At the end of the pressure holding stage of the die casting mold, the pressure wave transmitters are used to collect the pressure wave signal generated by solidification shrinkage. By analyzing the attenuation rate and frequency characteristics of the pressure wave signal, the distribution of internal shrinkage defects is determined. If the ratio of the peak attenuation amplitude of the pressure fluctuation signal to that of the standard sample is lower than the set critical value, it is determined that the area needs to be replenished with molten metal to eliminate shrinkage cavities; otherwise, the workpiece is confirmed to have reached the predetermined density standard and mold opening is allowed.

8. The engine throttle valve gradient cooling die-casting method according to claim 7, characterized in that, Achieving self-feeding of molten metal in defect areas by directional control of thermal field distribution includes the following steps: After the area where the peak attenuation of the pressure fluctuation signal is lower than the set critical value is marked as a defect area, the control terminal reactivates the heat maintenance control device corresponding to the area, so that a local high temperature zone is formed at its front end to soften the solidified shell. Increase the pressure of the hydraulic system on the back of the die-casting mold to force the residual molten metal to flow along the heat flow direction guided by the heat-conducting rod to fill the shrinkage cavity; at the same time, adjust the thermal conductivity of the nano-coating to the minimum value to slow down the heat loss on the feeding path.

9. An engine throttle valve gradient cooling die-casting system, characterized in that, Includes the following modules: The data acquisition module is used to acquire temperature gradient change signals and pressure fluctuation characteristics at the end of the pouring channel, the cavity junction and the transition zone between thin and thick structures in the die-casting mold, so as to generate a comprehensive sensor dataset. The region division module divides the region into high-intensity cooling zone, transition compensation zone, and heat maintenance zone based on the matching relationship between temperature gradient change signal and pressure fluctuation characteristics in the comprehensive sensor dataset, and generates a three-dimensional partition map. The temperature gradient change signal is matched with the temperature difference curve of adjacent regions and the peak shape of pressure fluctuation characteristics; if the temperature drop rate of a specific thin-walled region is detected to rise synchronously with the pressure peak frequency, the region is determined to be a high-intensity cooling zone. If the temperature maintenance time of the thick-walled region exceeds a multiple set for the adjacent region and is accompanied by a decrease in the amplitude of the pressure wave peak, the region is determined to be a heat maintenance zone. The transition region located at the junction of thin and thick walls exhibits both asymmetric temperature distribution and intermittent pressure peak abrupt changes, and this region is determined to be a transition compensation zone. The partitioning results are output as a 3D partition map through a visualization interface; The cooling control module is used to apply aerosol cooling in the high-intensity cooling zone, inject low-temperature medium in the transition compensation zone, and adjust the heat conduction components in the heat maintenance zone. The deformation detection module is used to detect the deformation offset of the workpiece surface during the cooling process and generate deformation correction instructions in combination with the preset deformation threshold. The compensation execution module triggers the compensation mechanism in the corresponding area according to the deformation correction command, and generates a deformation compensation feedback signal by adjusting the local thermal expansion of the die-casting mold and the thermal conductivity of the surface coating. The density verification module verifies the internal density of the workpiece based on the solidification shrinkage pressure echo characteristics and generates a shrinkage judgment result. The feeding control module, when the feeding determination result is not passed, achieves self-feeding of molten metal in the defect area by directional control of the thermal field distribution.

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