Dynamic self-adaptive closed-loop control system for injection parameters of die casting machine

Abstract

The application discloses a dynamic self-adaptive closed-loop control system for injection parameters of a die casting machine, which comprises the following steps: dividing a slow injection stroke into a detection interval and an adjustment interval, controlling a punch to run at a reference speed in the detection interval, calculating a flow resistance characteristic value according to average hydraulic pressure of a uniform speed section, hydraulic pressure of a slow injection, and the reference speed, and obtaining a flow resistance deviation; dividing the adjustment interval into a front section and a rear section, and performing sectional correction on a nominal slow injection speed in a direction opposite to the flow resistance deviation; and controlling the punch to run at a corrected speed, and performing online correction on the slow injection speed according to a deviation between actual hydraulic pressure and expected pressure. The application can dynamically adjust injection parameters according to a current metal liquid flow state, consider wave front stability and solidification risk, and improve working condition adaptability of the injection process and stability of casting forming quality.

Description

Technical Field

[0001] This application relates to the field of die casting forming control technology, specifically a dynamic adaptive closed-loop control system for injection parameters of a die casting machine. Background Technology

[0002] High-pressure die casting is characterized by high production efficiency, high forming accuracy, and suitability for mass production of complex thin-walled parts, and has been widely used in the production of automotive aluminum alloy structural components. Existing servo hydraulic die casting machines typically operate according to a pre-calibrated injection speed curve, switching between slow injection, fast injection, and pressurization stages based on the punch position; some equipment can collect punch displacement, speed, and hydraulic pressure for closed-loop tracking of the execution speed. The slow injection stage directly affects the wavefront morphology of the molten metal, air entrainment, and the solidification state before reaching the gate; its parameters are usually determined through trial molding.

[0003] In continuous production, the pouring temperature, pressure chamber wall temperature, molten metal transfer time, and injection waiting time all fluctuate. An unevenly distributed solidified layer may also form within the pressure chamber, causing variations in molten metal viscosity, effective flow cross-section, and propulsion resistance with each die and punch position. For large, thin-walled, or integrated structural components, a fixed slow injection curve is difficult to consistently adapt to actual operating conditions. Existing control methods often rely on nominal curves or data from the previous die for correction, making it difficult to respond promptly to random changes in the current die; single-point temperature measurement also struggles to characterize the non-uniform thermal state within the pressure chamber. Furthermore, applying the same correction direction throughout the slow injection process makes it difficult to simultaneously address the different requirements of suppressing wavefront rollover in the initial stage and reducing solidification risk in the later stage, easily leading to porosity, cold shuts, or improper switching to fast injection. Therefore, it is necessary to identify the actual flow state of the current die online and implement segmented adaptive adjustment and feedback correction within the same injection stroke. Summary of the Invention

[0004] The purpose of this application is to provide a dynamic adaptive closed-loop control system for injection parameters of a die-casting machine to solve the problems mentioned in the background art.

[0005] According to one aspect of this application, a dynamic adaptive closed-loop control method for injection parameters of a die-casting machine is provided, comprising the following steps: The slow injection stroke is divided into detection and adjustment intervals along the direction of punch movement. Within the detection range, the punch moves at a fixed reference speed, and the punch position and hydraulic pressure are collected synchronously. Based on the average hydraulic pressure of the uniform speed section of the detection range, the hydraulic pressure at the reference speed during air injection, and the reference speed, the flow resistance characteristic value is calculated. The flow resistance characteristic value is subtracted from the pre-calibrated reference value to obtain the flow resistance deviation. The adjustment range is divided into a front section and a rear section by a dividing point, and the nominal slow injection speed is corrected according to the flow resistance deviation. The correction direction for the front section is: when the flow resistance deviation is positive, the slow injection speed is reduced, and when it is negative, the slow injection speed is increased. The correction direction for the rear section is the opposite of that for the front section. The punch operates at the corrected slow injection speed within the adjustment range; during operation, the actual hydraulic pressure is continuously collected and compared with the expected pressure calculated based on the flow resistance deviation; if the deviation exceeds the tolerance zone, the slow injection speed is corrected online.

[0006] Preferably, the method for correcting the nominal slow injection speed is as follows: multiply the ratio of the flow resistance deviation to the reference value by the adjustment gain coefficient to obtain the speed correction ratio, and scale the nominal slow injection speed with the speed correction ratio to obtain the corrected slow injection speed; the front section and the rear section correspond to the independently calibrated first adjustment gain coefficient and second adjustment gain coefficient, respectively.

[0007] Preferably, the expected pressure is calculated based on the pressure baseline of each pre-calibrated punch position, the flow resistance deviation, and the execution speed at the current position; in the online correction, when the deviation between the actual hydraulic pressure and the expected pressure exceeds the tolerance band, the speed correction amount is determined based on the ratio of the deviation to the expected pressure, the correction gain coefficient, and the current speed, and the speed correction amount is applied in the correction direction corresponding to the front or rear segment of the current punch position.

[0008] Preferably, the method further includes: adjusting the calibrated switching position from slow injection to fast injection based on the ratio of the flow resistance deviation to the reference value and the switching position correction coefficient to obtain the corrected switching position; and triggering fast injection when the punch reaches the corrected switching position.

[0009] Preferably, the length of the detection interval is 15% to 25% of the total length of the slow injection stroke.

[0010] Preferably, the reference speed is the arithmetic mean of the upper and lower speed limits of the nominal slow injection speed curve within the corresponding position range of the detection interval.

[0011] Preferably, the dividing position is located at 55% to 70% of the distance between the start and end points of the adjustment range, and is determined during the process debugging stage by trial molding under deviation conditions and based on the porosity defect rate and cold shut defect rate of the casting.

[0012] Preferably, the values ​​of the first adjustment gain coefficient and the second adjustment gain coefficient are both in the range of 0.05 to 0.20; the calibration method is to set the temperature deviation condition during the process debugging stage, test the mold and detect the casting defect rate at each deviation level, and select the value that makes the corresponding type of defect rate the lowest.

[0013] Preferably, the modified slow injection speed is constrained by a safety upper limit and a safety lower limit, wherein the safety upper limit is 1.3 times the nominal slow injection speed and the safety lower limit is 0.7 times the nominal slow injection speed.

[0014] In another aspect, this application also provides a dynamic adaptive closed-loop control system for injection parameters of a die-casting machine, comprising: The stroke division module is used to divide the slow injection stroke into detection intervals and adjustment intervals along the direction of the punch movement. The flow resistance deviation calculation module is used to control the punch to run at a fixed reference speed within the detection range, synchronously collect the punch position and hydraulic pressure, calculate the flow resistance characteristic value based on the average hydraulic pressure of the uniform speed section of the detection range, the hydraulic pressure when running at the reference speed during air injection, and the reference speed, and subtract the pre-calibrated reference value from the flow resistance characteristic value to obtain the flow resistance deviation. The segmented speed correction module is used to divide the adjustment range into a front segment and a rear segment at the dividing position, and to correct the nominal slow injection speed according to the flow resistance deviation. In the front segment, the slow injection speed is reduced when the flow resistance deviation is positive and increased when the flow resistance deviation is negative. In the rear segment, the correction direction is opposite to that of the front segment. The injection execution and online correction module is used to control the punch to run within the adjustment range at the corrected slow injection speed. During operation, the actual hydraulic pressure is continuously collected, and the actual hydraulic pressure is compared with the expected pressure calculated based on the flow resistance deviation. When the deviation between the actual hydraulic pressure and the expected pressure exceeds the tolerance zone, the slow injection speed is corrected online.

[0015] This application sets a detection interval in the early stage of a single slow injection stroke. Based on the hydraulic pressure and air injection pressure during the uniform operation of the punch, it calculates the flow resistance deviation of the current die. This allows the controller to identify the combined effects of changes in molten metal temperature, solidification layer in the pressure chamber, and effective flow cross-section on the injection process without adding a pressure chamber temperature measuring device. Based on this, the slow injection parameters are adjusted within the same die, avoiding the adjustment lag caused by using fixed process curves or data from the previous die. During adjustment, based on the process difference that the early stage of slow injection focuses on stabilizing the molten metal wavefront while the later stage focuses on limiting continuous cooling and premature solidification, segmented speed corrections in opposite directions are used. Online correction is implemented through continuous comparison of actual pressure and expected pressure, allowing the injection speed to be dynamically adjusted according to changes in the resistance distribution within the pressure chamber. This improves the matching degree between the slow injection process and the current operating conditions, reduces the probability of molten metal entrapment, cold shuts, and improper switching from fast injection, and enhances the consistency of forming quality and process stability in the continuous production of large thin-walled die-cast parts. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of a dynamic adaptive closed-loop control method for injection parameters of a die-casting machine, provided in an embodiment of this application.

[0018] Figure 2 A flowchart for calculating the flow resistance deviation provided in an embodiment of this application.

[0019] Figure 3 The flowchart illustrates the online calibration process provided in this application.

[0020] Figure 4 This is a schematic diagram of a dynamic adaptive closed-loop control system for injection parameters of a die-casting machine, provided in an embodiment of this application.

[0021] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] This embodiment provides a dynamic adaptive closed-loop control method for injection parameters of a die-casting machine, applied to a horizontal cold chamber die-casting machine equipped with a servo hydraulic injection system. The die-casting machine's injection cylinder is equipped with a hydraulic pressure sensor, and the punch is equipped with a displacement encoder. The sampling frequency of the hydraulic pressure sensor is, for example, not less than 500Hz, and the resolution of the displacement encoder is, for example, not less than 0.1mm. This method is particularly suitable for the die-casting production of aluminum alloy automotive structural parts, such as large, thin-walled parts like integrated die-cast rear floors, shock absorber towers, and battery trays for new energy vehicles. In this type of production, the pressure chamber diameter is typically in the range of 120mm to 220mm, the slow injection stroke is in the range of 300mm to 800mm, and the duration of a single slow injection process is approximately 1 to 3 seconds. This method utilizes the existing pressure sensor and displacement encoder of the die-casting machine to collect data and can be deployed on existing servo hydraulic die-casting machines through control software upgrades.

[0024] The following detailed description, in conjunction with specific embodiments, illustrates the implementation process of the dynamic adaptive closed-loop control method for injection parameters of a die-casting machine described in this application. It should be noted that this embodiment is merely for explaining this application and not for limiting the scope of protection of this application. Any conventional adjustments or substitutions made by those skilled in the art to the steps without departing from the concept of this application should be included within the scope of protection of this application.

[0025] like Figure 1 As shown in the figure, this application discloses a schematic diagram of a dynamic adaptive closed-loop control method for injection parameters of a die-casting machine, including the following method steps: Step S1: Divide the slow injection stroke into a detection zone and an adjustment zone along the direction of the punch movement. Along the direction of the punch movement, the slow injection stroke is divided into two functionally distinct zones: the section near the beginning of the stroke is the detection zone, and the remaining portion is the adjustment zone. The detection zone is used to acquire information on the flow conditions of the molten metal in the current die during the initial stage of slow injection, providing input for subsequent speed correction; the adjustment zone corrects the slow injection speed curve in real time based on the information acquired in the detection zone, and overlays online correction during execution.

[0026] Specifically, let the total length of the slow injection stroke be... The unit is mm, and the length of the detection interval is... . The range of values ​​is The value is 15% to 25%. If the value is too small, the uniform stroke of the punch to establish a stable pressure signal within the detection range is insufficient, resulting in a larger proportion of transient components in the pressure data used for subsequent calculations and a decrease in the reliability of the eigenvalues. If the value is too large, the stroke of the adjustment range is shortened, leaving insufficient space for speed correction. In one example, the total slow injection stroke of a certain integrated die-casting post-floor mold... =600mm, Take 120mm, which accounts for approximately 20% of the total stroke.

[0027] Step S2: Calculate the flow resistance characteristic value and flow resistance deviation within the detection interval. Within the detection interval, the punch operates at a fixed reference speed, and the punch position and hydraulic pressure are simultaneously collected. Based on the average hydraulic pressure during the uniform speed segment of the detection interval, the hydraulic pressure during pneumatic injection at the reference speed, and the reference speed itself, the flow resistance characteristic value is calculated. The flow resistance deviation is obtained by subtracting the pre-calibrated reference value from the flow resistance characteristic value.

[0028] Specifically, such as Figure 2 As shown, Figure 2 The flowchart for calculating the flow resistance deviation provided in this application embodiment shows that in step S201, the punch runs at a fixed reference speed and the punch position and hydraulic pressure are collected synchronously.

[0029] In one embodiment, the punch operates at a fixed reference speed within the detection range. run, The unit is m / s. During the process debugging phase, the upper limit of the nominal slow injection speed curve within the corresponding position range of the detection interval was determined. With speed lower limit Arithmetic mean:

[0030] in and All values ​​are in m / s. In one example, the nominal velocity curve within the detection range is 0.15 m / s to 0.25 m / s. We set the speed to 0.20 m / s. Under uniform velocity conditions, the punch has no acceleration, and the hydraulic pressure does not contain an inertial force component. The pressure signal caused by the resistance of molten metal flow is more clearly defined, which is beneficial for subsequent feature value extraction.

[0031] During the operation of the punch, the system synchronously acquires the position of the punch at a sampling frequency of no less than 500Hz. and hydraulic pressure The punch accelerates from its starting position to... After entering the uniform speed phase, the system records the arithmetic mean of the hydraulic pressure at each sampling point within the uniform speed segment, denoted as . , unit MPa.

[0032] In step S202, the flow resistance characteristic value is calculated based on the average hydraulic pressure of the uniform speed section of the detection interval, the air injection hydraulic pressure, and the reference speed.

[0033] Among them, the characteristic value of flow resistance This refers to the additional flow resistance generated by the molten metal on the punch's movement at a unit punch speed, measured in MPa·s / m. It comprehensively reflects the viscosity state and effective flow cross-section size of the molten metal in the current die's pressure chamber. When the molten metal temperature is low or the solidified layer on the inner wall of the pressure chamber is thick, the flow resistance of the molten metal on the punch increases. The temperature increases accordingly; when the temperature is too high or the solidified layer is too thin. Decrease. The calculation formula is:

[0034] in The average hydraulic pressure, measured in MPa, is measured during the constant-speed section of the test interval. Under air injection conditions (no molten metal in the pressure chamber), the punch operates at a reference speed. Hydraulic pressure during operation, in MPa, is measured during the equipment calibration phase and reflects the inherent resistance caused by the mechanical friction of the injection system itself and the loss of hydraulic pipelines. The reference speed is expressed in m / s.

[0035] The reason for using flow resistance characteristics instead of directly measuring the molten metal temperature by installing a temperature sensor inside the pressure chamber is understandable. This is because the temperature distribution of the molten metal inside the pressure chamber is extremely uneven; the surface temperature is higher than the temperature of the layer in contact with the wall, and a temperature gradient also exists along the length of the pressure chamber. The temperature of the molten metal near the gate is usually higher than that near the punch. Temperature measurements at a single location cannot characterize the overall thermal state. It is calculated from the comprehensive resistance encountered by the punch during the propulsion of molten metal. It is a holistic reflection of the viscosity of molten metal and the effective flow cross section, and is directly related to the physical information required for optimizing slow injection speed.

[0036] In one example, the air injection pressure calibrated on an aluminum alloy ADC12 production line. =1.2MPa, average pressure in the testing range under standard operating conditions Approximately 3.2 MPa =0.20m / s, then =(3.2-1.2) / 0.20=10.0MPa·s / m.

[0037] In step S203, the flow resistance deviation is obtained by subtracting the pre-calibrated reference value from the flow resistance characteristic value.

[0038] In one embodiment, during the process debugging phase, 20 to 30 continuous injection cycles are performed under standard operating conditions, and the values ​​of each cycle are taken. The arithmetic mean is used as the benchmark value. Standard operating conditions refer to the conditions where the pouring temperature, pressure chamber preheating temperature, and post-pouring waiting time are all within the middle values ​​of the process specifications. Taking aluminum alloy ADC12 as an example, the pouring temperature can be configured as 660℃, the pressure chamber preheating temperature as 200℃, and the waiting time as 2 seconds.

[0039] During mass production, each module is calculated. Then, subtract the baseline value from it to obtain the flow resistance deviation for the current module:

[0040] The unit is MPa·s / m. This indicates that the current flow resistance of the molten metal is too high, which corresponds to a low temperature or a thick solidified layer. Conversely, in the aforementioned example, if a certain mold has a longer waiting time after casting, If it rises to 3.5 MPa, then =(3.5-1.2) / 0.20=11.5MPa·s / m, =11.5-10.0=1.5MPa·s / m. This deviation is used in subsequent steps for speed correction, online correction, and position switching correction within the adjustment range.

[0041] The fluctuations in the thermal state of molten metal during die casting production primarily stem from three sources: the chamber wall temperature changes gradually with continuous production; the temperature of the molten metal scooped out each time fluctuates; and the waiting time between pouring and injection start varies due to differences in the operating cycle. The detection interval allows the system to acquire the actual flow conditions of the molten metal in the current die during the early stages of the slow injection stroke, providing real-time data for speed adjustments in subsequent strokes within the same die, rather than relying on historical data from the previous die. This real-time acquisition method within a single die eliminates the inherent lag of traditional inter-die adaptive methods when facing random fluctuations.

[0042] Step S3: Divide the adjustment range into a front section and a rear section at the dividing point, and correct the nominal slow injection speed according to the flow resistance deviation. Specifically, the adjustment range is divided into a front section and a rear section at the dividing point, and the nominal slow injection speed is corrected according to the flow resistance deviation. The correction direction for the front section is: decrease the slow injection speed when the flow resistance deviation is positive, and increase the slow injection speed when it is negative. The correction direction for the rear section is opposite to that of the front section.

[0043] The punch passes the end of the detection interval Then it enters the adjustment range. The controller detects when the punch reaches... Completed within approximately 2 to 5 milliseconds Calculation, The determination and generation of the corrected speed curve are carried out during this transition period, during which the punch still operates at the reference speed. During operation, the corresponding displacement does not exceed 1mm, and its impact on the effective length of the adjustment range is negligible. The speed command update cycle of existing servo hydraulic injection systems is typically 1ms, which meets the above calculation time requirements.

[0044] In one embodiment, a boundary position is set within the adjustment range. The unit is mm, and the adjustment range is divided into the first segment ( to ) and the latter part ( to The segmentation is based on the fact that the main issues affecting casting quality differ at different points in the slow injection stroke. In the first stage of the stroke, the molten metal stays in the pressure chamber for a short time, with ample stroke margin, and the main risk to casting quality is wavefront entrapment of air. In the second stage of the stroke, the molten metal continuously dissipates heat, and the accumulated cooling increases, changing the main risk to insufficient fluidity or premature solidification before reaching the gate.

[0045] in, Located at 55% to 70% of the distance between the start and end points of the adjustment range. Specifically, during the process debugging phase under deviation conditions (e.g., reducing the pouring temperature by 15°C), several candidate boundary positions are set, such as one group each at 55%, 60%, 65%, and 70% of the adjustment range length. Each group undergoes 10 to 15 injection cycles. After X-ray inspection of the casting, the porosity defect rate in the first region and the cold shut defect rate in the second region of each group are statistically analyzed. The two types of defect rates are assigned weights according to the severity classification in the product quality standards (e.g., porosity weight 0.6, cold shut weight 0.4), and a weighted sum is calculated. The position that minimizes the weighted sum is selected as the boundary position. In one example, the starting point of the adjustment interval is 120mm, the ending point is 600mm, and the interval length is 480mm. Pick mm.

[0046] In one embodiment, the front end ( Wavefront stability is the primary constraint. When the molten metal temperature is low and the solidified layer is thick, the effective flow cross-section in the pressure chamber decreases, and the liquid surface depth becomes shallower. Under shallow liquid surface conditions, the same injection speed is more likely to cause wavefront instability and rollover, trapping air into the pressure chamber. Therefore, the correction direction in the first stage is: when the flow resistance deviation is positive, reduce the slow injection speed; when it is negative, increase the slow injection speed.

[0047] The latter part ( Solidification risk becomes the primary concern. When the molten metal temperature is low, if the injection speed is further reduced in the later stages, the time it takes for the molten metal to pass through the later stages increases, further accumulating heat loss and increasing the likelihood of premature solidification at the gating inlet. Therefore, the correction direction in the later stages is opposite to that in the earlier stages: when the flow resistance deviation is positive, increase the slow injection speed; when it is negative, decrease the slow injection speed.

[0048] The physical basis of the above-mentioned rule that the correction directions of the front and rear sections are opposite is that the same temperature deviation causes different types of defects at different positions in the stroke: the reduction of the effective flow cross section in the front section reduces the wavefront stability margin, and the speed needs to be reduced to maintain the wavefront shape; the cumulative cooling in the rear section increases the risk of solidification, and the speed needs to be increased to shorten the residence time of the molten metal in the tail section of the pressure chamber.

[0049] According to embodiments of this disclosure, the ratio of the flow resistance deviation to a reference value is used for correction. Multiplying by the adjustment gain coefficient yields the velocity correction ratio, which is then used to scale the nominal slow injection velocity. The first adjustment gain coefficient is used in the initial stage. The latter part uses a second adjustable gain coefficient. Both are dimensionless parameters and are calibrated independently. The corrected slow injection velocity is:

[0050] The corrected slow injection velocity in the later stage is:

[0051] in and The front and rear positions are respectively. Corrected slow injection velocity, in m / s; The nominal slow injection speed curve calibrated during the process debugging phase is located at... The value at this location is in m / s; when When the value inside the parentheses in the first part of the formula is less than 1, the speed decreases; when the value inside the parentheses in the second part of the formula is greater than 1, the speed increases. The situation is the opposite at other times.

[0052] about and The values ​​range from 0.05 to 0.20. The calibration method involves setting 2 to 3 temperature deviation levels during the process debugging phase. For example, reducing the pouring temperature by 10℃ is the first level, and reducing it by 20℃ is the second level. Several tests are conducted at each level. and Candidate values ​​(e.g., 0.05, 0.10, 0.15, 0.20) were selected, and each group underwent 10 to 15 injection cycles. The castings were then inspected by X-ray. The optimal value is selected based on the porosity of the previous region. The optimal value is selected based on the cold insulation rate of the subsequent region. If there are differences in the optimal values ​​under each level, the arithmetic mean is taken.

[0053] In one example =10.0MPa·s / m, =1.5MPa·s / m, =0.12, =0.15. Nominal speed at a certain position in the preceding segment. =0.22m / s, after correction =0.22×(1-0.12×1.5 / 10.0)=0.22×0.982=0.216m / s, the speed decreases by about 1.8%. At the same nominal speed position in the later section... =0.22×(1+0.15×1.5 / 10.0)=0.22×1.0225=0.225m / s, the speed increases by about 2.3%.

[0054] Optionally, the corrected slow injection velocity is constrained by a safety upper limit and a safety lower limit. The safety upper limit is 1.3 times the nominal slow injection velocity, and the safety lower limit is 0.7 times the nominal slow injection velocity. When the corrected velocity exceeds this range, the corresponding boundary value is used.

[0055] Step S4: The punch operates within the adjustment range at the corrected slow injection speed and undergoes online calibration. Specifically, the punch operates within the adjustment range at the corrected slow injection speed; during operation, the actual hydraulic pressure is continuously collected and compared with the expected pressure calculated based on the flow resistance deviation. If the deviation exceeds the tolerance zone, the slow injection speed is calibrated online.

[0056] According to an embodiment of this disclosure, after the punch enters the adjustment range, it operates according to the corrected speed curve calculated in step S3. The correction in step S3 is based on a single feature value obtained from the detection range. This is a feedforward compensation mechanism. In actual production, the solidified layer in the pressure chamber is unevenly distributed along its length, and the conditions reflected in the detection range may not fully represent the actual situation at each position in the adjustment range. To compensate for this deviation, the system continuously compares the actual hydraulic pressure with the expected pressure during operation, and performs online correction on the slow injection speed when the deviation exceeds the tolerance zone.

[0057] like Figure 3 As shown, Figure 3 The online calibration flowchart provided in this application embodiment shows that in step S301, the expected pressure is calculated based on the pressure baseline, the flow resistance deviation, and the execution speed.

[0058] Under standard operating conditions during the process debugging phase, the system records the average hydraulic pressure at each punch position to form a pressure baseline. The unit is MPa. During mass production, the controller calculates the expected pressure based on the pressure baseline, the flow resistance deviation of the current cycle, and the execution speed at the current position.

[0059] in For position Expected pressure at the location, in MPa; The calibrated pressure baseline value is expressed in MPa. This is the deviation in flow resistance, expressed in MPa·s / m. The execution speed at the current position, in m / s.

[0060] Defined as the additional resistance per unit speed, the additional component under standard operating conditions. Already included In the current module. and After the simultaneous change, the increment of the additional component is approximately: The expected pressure is then superimposed on the baseline.

[0061] In one example, at a certain location =4.0MPa, =1.5MPa·s / m, =0.216m / s, =4.0 + 1.5 × 0.216 = 4.324 MPa.

[0062] In step S302, when the deviation exceeds the tolerance band, a speed correction amount is applied according to the correction direction. Specifically, the system continuously collects the actual hydraulic pressure within the adjustment range. to compare it with expected pressure Comparison. Setting tolerance bands. The width is taken as a certain percentage of the expected pressure, ranging from 8% to 12%. The calibration method involves continuous injection for at least 30 cycles under standard operating conditions, and the standard deviation of the actual pressure from the expected pressure at each location is calculated. ,Pick for to Values ​​between these ranges, when converted to percentages, typically fall between 8% and 12%. In one example, we take 10%, which is... .

[0063] If the deviation between the actual hydraulic pressure and the expected pressure does not exceed the tolerance band, the corrected speed calculated in step S3 remains unchanged. If the deviation exceeds the tolerance band, the system determines the speed correction amount based on the ratio of the deviation to the expected pressure, the correction gain coefficient, and the current speed.

[0064] in The gain coefficient is used for correction, and its value ranges from 0.03 to 0.10. This is a dimensionless relative value of the pressure deviation. The current execution speed is expressed in m / s.

[0065] in The calibration method involves artificially introducing a step disturbance under standard operating conditions, such as suddenly extending the waiting time by 2 seconds in a certain module, and setting the following parameters: Several candidate values ​​(such as 0.03, 0.05, 0.08, and 0.10) were used to observe the pressure and velocity response curves of subsequent modules at each candidate value. The value that resulted in the fastest velocity return to the tolerance band without significant oscillations was selected. value.

[0066] The direction of the speed correction is determined by the correction direction corresponding to the current position of the punch in the front or rear section. Specifically, when the actual hydraulic pressure is higher than expected, it indicates that the actual resistance is greater than the feedforward estimate. If the punch is in the front section, the speed is further reduced, i.e., the current speed is reduced by... If it is in the later stage, the speed will be further increased, that is, the current speed plus... When the actual hydraulic pressure is lower than expected, the correction direction is reversed, and this direction rule is consistent with the correction direction of the preceding and following sections in step S3.

[0067] In one example =4.324MPa, =0.432MPa; Actual pressure =4.82MPa, deviation 4.82-4.324=0.496MPa, exceeding the tolerance zone. Let... =0.06, =0.216m / s, then =0.06×0.496 / 4.324×0.216≈0.0015m / s. If this position is in the earlier stage, the speed correction is 0.216-0.0015=0.2145m / s.

[0068] In this process, the feedforward compensation in step S3 and the online correction in step S4 work together. The feedforward component takes effect immediately when entering the adjustment range based on the prior information of the detection range, while the online correction component continuously corrects the error in the feedforward estimation based on the actual pressure deviation during the execution process, thus compensating for the error caused by factors such as uneven distribution of the solidified layer in the feedforward estimation.

[0069] In some embodiments, the method further includes offset correction for the transition from slow injection to fast injection; specifically, the transition from slow injection to fast injection is triggered when the punch reaches a set position. The switching position under calibration conditions is denoted as... The unit is mm. When the molten metal temperature is low, the solidified layer is thicker, the effective volume of the molten metal is reduced, and the stroke of the punch required for the molten metal front to reach the gate inlet is increased. If the switching position is still taken from the calibration value, the residual air in front of the punch will be pressed into the cavity with the molten metal when fast injection starts. When the temperature is high, the situation is the opposite. The molten metal front reaches the gate earlier. If the switching position is not moved forward, the molten metal may enter the cavity at a slow rate, which may cause filling defects. The system uses the ratio of the flow resistance deviation to the reference value and the switching position correction coefficient. Offset correction for calibration switching position:

[0070] in The corrected switching position is in mm; This is the position switching correction factor, in mm, with a value range of 2 to 15 mm.

[0071] in During the process debugging phase, calibration was performed. Specifically, the switching position offset was gradually adjusted under deviation conditions, using the steepness of the rising edge of the pressure waveform at the moment of rapid switching as the criterion (a steeper rising edge indicates less residual air during switching). The optimal offset was recorded for each deviation level, and the relationship between the deviation level and the offset was linearly regressed using the least squares method to obtain... The punch reaches the corrected switching position. Time-triggered rapid injection.

[0072] In one example =550mm, =8mm, =0.15, =550+8×0.15=551.2mm.

[0073] According to the embodiments of this disclosure, the above method requires parameter calibration before mass production. Specifically, it is performed in the following order during the process debugging stage: First, air injection calibration: no molten metal is injected into the pressure chamber, and the punch operates at a reference speed. Run slow injection and record the average hydraulic pressure as... Optionally, repeat 3 to 5 times and take the average. Then perform standard operating condition calibration: pouring temperature, pressure chamber temperature, and waiting time are all taken as the median values ​​of the process specifications. Perform 20 to 30 consecutive injections and take the average value of each injection. The average value is used as Simultaneously record the average hydraulic pressure at each location to form a pressure baseline. The third step is deviation condition calibration: Two to three deviation levels are manually set (for example, reducing the pouring temperature by 15°C is the first level, and extending the waiting time to 5 seconds is the second level). Each level is subjected to 10 to 15 injection cycles. After X-ray inspection, the castings are calibrated according to the aforementioned method. , , , , and All parameters are written into the die-casting machine controller memory.

[0074] Optionally, during mass production, after accumulating a set number of cycles (e.g., 500 cycles), the percentage of cycles with excessive porosity and the percentage of cycles with excessive cold shut in that batch are calculated, and the first adjustment gain coefficient is adjusted based on the comparison of these two percentages. Second adjustment gain coefficient If the proportion of excessive porosity is higher than the proportion of excessive cold shut, increase... Conversely, increase Each adjustment shall not exceed 10% of the current value.

[0075] Therefore, the above method completes the entire process of detection, correction, execution, and calibration within a single slow injection stroke. The flow resistance characteristic value obtained in the detection interval provides a real-time basis for updating the velocity correction in the adjustment interval on a module-by-module basis; the adjustment rule with opposite correction directions in the first and second stages simultaneously considers both wavefront stability and solidification risk constraints within the stroke, reducing the proportion of defects caused by neglecting one aspect due to adjustment in a single direction; online correction compensates for the error of the feedforward estimation, ensuring that the entire control process matches the actual operating conditions.

[0076] It should be noted that although the operations of the method of this application are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. On the contrary, the steps depicted in the flowchart can be performed in a different order. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0077] Please see Figure 4 , Figure 4 This application provides a dynamic adaptive closed-loop control system for injection parameters of a die-casting machine. The system embodiment is similar to... Figure 1 Corresponding to the method embodiment shown, the system specifically includes: The stroke division module is used to divide the slow injection stroke into detection intervals and adjustment intervals along the direction of the punch movement. The flow resistance deviation calculation module is used to control the punch to run at a fixed reference speed within the detection range, synchronously collect the punch position and hydraulic pressure, calculate the flow resistance characteristic value based on the average hydraulic pressure of the uniform speed section of the detection range, the hydraulic pressure when running at the reference speed during air injection, and the reference speed, and subtract the pre-calibrated reference value from the flow resistance characteristic value to obtain the flow resistance deviation. The segmented speed correction module is used to divide the adjustment range into a front segment and a rear segment at the dividing position, and to correct the nominal slow injection speed according to the flow resistance deviation. In the front segment, the slow injection speed is reduced when the flow resistance deviation is positive and increased when the flow resistance deviation is negative. In the rear segment, the correction direction is opposite to that of the front segment. The injection execution and online correction module is used to control the punch to run within the adjustment range at the corrected slow injection speed. During operation, the actual hydraulic pressure is continuously collected, and the actual hydraulic pressure is compared with the expected pressure calculated based on the flow resistance deviation. When the deviation between the actual hydraulic pressure and the expected pressure exceeds the tolerance zone, the slow injection speed is corrected online.

[0078] like Figure 4 As shown, the dynamic adaptive closed-loop control system for injection parameters of a die-casting machine includes a controller, a displacement encoder, a hydraulic pressure sensor, a servo hydraulic injection actuator, a punch, and an injection cylinder. The controller is equipped with a stroke division module, a flow resistance deviation calculation module, a segmented speed correction module, and an injection execution and online correction module. The displacement encoder and hydraulic pressure sensor respectively collect the punch position and the injection cylinder hydraulic pressure and send the results to the controller. The flow resistance deviation calculation module determines the flow resistance deviation based on the average hydraulic pressure, air injection pressure, reference speed, and reference value within the detection range; the segmented speed correction module corrects the nominal slow injection speed of the first and second segments of the adjustment range accordingly. The injection execution and online correction module outputs speed control commands to the servo hydraulic injection actuator based on the correction results and compares the actual hydraulic pressure with the expected pressure. Online correction is implemented when the pressure deviation exceeds the tolerance zone, thus forming a closed-loop control process of position and pressure acquisition, parameter calculation, speed adjustment, injection execution, and status feedback.

[0079] Each processing unit and / or module in the embodiments of this application can be implemented by an analog circuit that implements the functions described in the embodiments of this application, or by software that executes the functions described in the embodiments of this application.

[0080] Based on the same inventive concept, this application also provides an electronic device, such as... Figure 5 As shown, Figure 5 This is a schematic diagram of an electronic device structure according to an embodiment of the present disclosure. The method corresponding to the electronic device can be the method in the foregoing embodiments, and its problem-solving principle is similar to that method. The electronic device provided in this application includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the methods and / or technical solutions of the foregoing embodiments of the present application.

[0081] Specifically, the methods and / or embodiments in this application can be implemented as computer software programs. For example, the embodiments disclosed in this application include a computer program product comprising a computer program carried on a storage medium, the computer program containing program code for performing the methods shown in the flowchart. When the computer program is executed by a central processing unit, it performs the functions defined in the methods of this application.

[0082] Another embodiment of this application provides a computer-readable storage medium having computer program instructions stored thereon, which can be executed by a processor to implement the methods and / or technical solutions of any one or more embodiments of this application described above.

[0083] The flowcharts or block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of electronic devices, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-specific system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0084] The above description represents the preferred embodiments of the present invention. It should be noted that, for those skilled in the art, various improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A dynamic adaptive closed-loop control method for injection parameters of a die-casting machine, characterized in that, Includes the following steps: The slow injection stroke is divided into detection and adjustment intervals along the direction of punch movement. Within the detection range, the punch moves at a fixed reference speed, and the punch position and hydraulic pressure are collected synchronously. Based on the average hydraulic pressure of the uniform speed section of the detection range, the hydraulic pressure at the reference speed during air injection, and the reference speed, the flow resistance characteristic value is calculated. The flow resistance characteristic value is subtracted from the pre-calibrated reference value to obtain the flow resistance deviation. The adjustment range is divided into a front section and a rear section by a dividing point, and the nominal slow injection speed is corrected according to the flow resistance deviation. The correction direction for the front section is: when the flow resistance deviation is positive, the slow injection speed is reduced, and when it is negative, the slow injection speed is increased. The correction direction for the rear section is the opposite of that for the front section. The punch operates at the corrected slow injection speed within the adjustment range; during operation, the actual hydraulic pressure is continuously collected and compared with the expected pressure calculated based on the flow resistance deviation; if the deviation exceeds the tolerance zone, the slow injection speed is corrected online.

2. The method according to claim 1, characterized in that, The method for correcting the nominal slow injection speed is as follows: multiply the ratio of the flow resistance deviation to the reference value by the adjustment gain coefficient to obtain the speed correction ratio, and scale the nominal slow injection speed with the speed correction ratio to obtain the corrected slow injection speed. The front section and the back section correspond to independently calibrated first and second adjustment gain coefficients, respectively.

3. The method according to claim 1, characterized in that, The expected pressure is calculated based on the pressure baseline of each pre-calibrated punch position, the flow resistance deviation, and the execution speed at the current position. In the online correction, when the deviation between the actual hydraulic pressure and the expected pressure exceeds the tolerance band, the speed correction amount is determined based on the ratio of the deviation to the expected pressure, the correction gain coefficient, and the current speed, and the speed correction amount is applied in the correction direction corresponding to the front or rear segment of the current punch position.

4. The method according to claim 1, characterized in that, Also includes: Based on the ratio of the flow resistance deviation to the reference value and the switching position correction coefficient, the calibrated switching position from slow injection to fast injection is offset and corrected to obtain the corrected switching position; fast injection is triggered when the punch reaches the corrected switching position.

5. The method according to claim 1, characterized in that, The length of the detection interval is 15% to 25% of the total length of the slow injection stroke.

6. The method according to claim 1, characterized in that, The reference speed is the arithmetic mean of the upper and lower speed limits of the nominal slow injection speed curve within the corresponding position range of the detection interval.

7. The method according to claim 1, characterized in that, The dividing point is located at 55% to 70% of the distance between the start and end points of the adjustment range. It is determined during the process debugging stage by using a test mold under deviation conditions and judging based on the porosity defect rate and cold shut defect rate of the casting.

8. The method according to claim 2, characterized in that, The values ​​of the first adjustment gain coefficient and the second adjustment gain coefficient are both in the range of 0.05 to 0.

20. The calibration method is to set the temperature deviation condition during the process debugging stage, test the mold and detect the defect rate of the casting under each deviation level, and select the value that makes the corresponding type of defect rate the lowest.

9. The method according to claim 1, characterized in that, The modified slow injection speed is constrained by a safety upper limit and a safety lower limit, wherein the safety upper limit is 1.3 times the nominal slow injection speed and the safety lower limit is 0.7 times the nominal slow injection speed.

10. A dynamic adaptive closed-loop control system for injection parameters of a die-casting machine, characterized in that, include: The stroke division module is used to divide the slow injection stroke into detection intervals and adjustment intervals along the direction of the punch movement. The flow resistance deviation calculation module is used to control the punch to run at a fixed reference speed within the detection range, synchronously collect the punch position and hydraulic pressure, calculate the flow resistance characteristic value based on the average hydraulic pressure of the uniform speed section of the detection range, the hydraulic pressure when running at the reference speed during air injection, and the reference speed, and subtract the pre-calibrated reference value from the flow resistance characteristic value to obtain the flow resistance deviation. The segmented speed correction module is used to divide the adjustment range into a front segment and a rear segment at the dividing position, and to correct the nominal slow injection speed according to the flow resistance deviation. In the front segment, the slow injection speed is reduced when the flow resistance deviation is positive and increased when the flow resistance deviation is negative. In the rear segment, the correction direction is opposite to that of the front segment. The injection execution and online correction module is used to control the punch to run within the adjustment range at the corrected slow injection speed. During operation, the actual hydraulic pressure is continuously collected, and the actual hydraulic pressure is compared with the expected pressure calculated based on the flow resistance deviation. When the deviation between the actual hydraulic pressure and the expected pressure exceeds the tolerance zone, the slow injection speed is corrected online.

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