An optimization control method for a wheel hub liquid die forging forming process

Abstract

This invention relates to the field of process control technology in metal material forming, and discloses an optimized control method for a wheel hub liquid forging process. A punch displacement sensor and a liquid forging pressure sensor are set up to synchronously collect and calibrate displacement and pressure signals, and perform zero-point correction to obtain a displacement and pressure sampling sequence. The displacement change rate, pressure change rate, and effective compensation displacement increment are calculated, and the filling end and compensation evaluation termination intervals are obtained according to statistical thresholds. The effective compensation displacement is accumulated within the evaluation interval, and the pressure area is obtained by integrating the pressure to construct a smoothness index. The start time of secondary pressurization, platform pressure, and duration are discretized into a candidate set to generate a target pressure trajectory that meets the pressure change rate constraint and calculates the smoothness. Optimal parameters are screened and corrected, and the pressure command sequence is output and solidified for distribution to the hydraulic system, achieving quantifiable optimization and stable execution of parameters.

Description

Technical Field

[0001] This invention relates to the field of process control technology in metal material forming, specifically to an optimized control method for a wheel hub liquid forging process. Background Technology

[0002] Liquid forging of wheel hubs falls under the technical field of metal material pressure processing and casting-forging composite forming. Existing liquid forging processes for wheel hubs typically employ a basic process path of "filling—holding pressure—feeding compensation." Equipment often has the capability for one or more pressurization cycles, but the setting of the pressurization curve largely relies on the experience of process engineers, using preset fixed holding pressures, holding times, or simple stepped pressure curves for control. While punch displacement and chamber pressure signals can be acquired by sensors, they are often only used for process monitoring and simple alarms at the process control level, lacking a quantitative evaluation index system that can directly guide the setting of the secondary pressurization curve. In existing liquid forging wheel hub processes, the determination of the filling end time and the critical feeding stage usually relies on estimated time windows, punch stroke thresholds, or empirical critical values ​​of pressure changes for rough division. This fails to dynamically determine the effective working range of the feeding channel based on the actual changes in metal filling and solidification shrinkage behavior in each heat, leading to a deviation between the start and stop times of secondary pressurization and the actual feeding requirements, easily resulting in insufficient or excessive feeding. Meanwhile, existing technologies generally lack a quantitative description of the "unobstructed state of the feeding channel," and can only make indirect judgments through post-event quality indicators such as macroscopic defects, flaw detection results, or scrap rates. They cannot systematically evaluate the effective feeding displacement capacity formed by a unit pressure input through an indicator that is synergistically related to displacement, pressure, and time during the process design stage. Current methods for setting secondary pressure curves typically involve conservative designs based solely on "high enough pressure" and "long enough time," without establishing a calculable relationship between the equipment's allowable pressure limits, pressure change rate constraints, and the feeding requirements of the casting. As a result, on the one hand, to avoid shrinkage cavities and porosity, the platform pressure is blindly increased or the holding time is extended, leading to increased energy consumption, increased equipment load, and decreased mold life. On the other hand, under certain operating conditions, due to the secondary pressure starting too late, rising too slowly, or the effective range deviating from the actual feeding sensitive stage, the feeding channel fails to maintain good metal supply unobstructedness during critical stages, resulting in insufficient internal density and fluctuations in dimensional stability and fatigue performance. Furthermore, existing technologies lack a unified evaluation standard based on collected data across multiple batches and products, making it impossible to use the same indicator to horizontally compare the compensation efficiency of different secondary pressurization curves, and also making it inconvenient to systematically correlate historical process parameters with quality results.

[0003] Therefore, this case aims to propose an optimized control method for the liquid forging process of wheel hubs. First, through sensor calibration and zero-point correction, comparable discrete sequences of displacement and pressure are obtained. Then, displacement velocity, pressure change rate, and effective displacement increments (retaining only the "metal feeding into the cavity") are calculated. These quantitative indicators characterize the metal flow and the smoothness of the feeding channel during the feeding stage. Based on this, statistical thresholds are used to automatically identify the end of filling and the termination of feeding evaluation, constructing an evaluation time interval that focuses only on feeding behavior. Within this interval, the total effective feeding displacement is combined with the pressure area to form a feeding channel smoothness index. Around three types of process parameters—secondary pressurization start time, platform pressure, and duration—the scheme constructs a set of candidate parameters, generating target pressure trajectories for secondary pressurization that satisfy the pressure change rate constraint one by one. The smoothness under each candidate parameter is calculated, and through sorting and constraint correction, the optimal secondary pressurization parameters that satisfy equipment capacity and process boundaries are obtained. Finally, a pressure setting command sequence that can be directly issued to the hydraulic system is formed. Summary of the Invention

[0004] This invention provides an optimized control method for the liquid forging process of wheel hubs, which helps to solve the problems mentioned in the background art.

[0005] This invention provides the following technical solution: an optimized control method for a wheel hub liquid forging process, comprising:

[0006] Set up a punch displacement sensor and a liquid forging pressure sensor, synchronously collect displacement voltage signals and pressure voltage signals according to the sampling period, complete calibration and zero point correction, and generate punch displacement sampling sequence and liquid forging pressure sampling sequence;

[0007] The displacement change rate sequence and pressure change rate sequence are calculated based on the punch displacement sampling sequence and the liquid forging pressure sampling sequence, and an effective compensation displacement increment sequence is constructed according to the displacement increment.

[0008] Based on the statistical thresholds of the displacement change rate sequence and the pressure change rate sequence, the filling end sampling interval and the shrinkage evaluation termination sampling interval are obtained, forming the shrinkage evaluation time interval;

[0009] The total effective shrinkage displacement is obtained by accumulating the effective shrinkage displacement increment within the shrinkage assessment time interval. The pressure area is obtained by integrating the liquid forging pressure over time. A smoothness index is constructed based on the total effective shrinkage displacement and the pressure area.

[0010] Set the start time of secondary boost, the pressure of the secondary boost platform, and the duration of secondary boost as decision variables for secondary boost, and generate a set of candidate parameters for secondary boost discretization within the allowable range;

[0011] For each set of parameters in the secondary boost candidate parameter set, construct a secondary boost target pressure trajectory that satisfies the pressure change rate constraint, form a pressure target sequence, and calculate the corresponding smoothness index based on the pressure target sequence within the compensation evaluation time interval;

[0012] Select the parameter group with the highest smoothness index from the set of secondary boosting candidate parameters, obtain the optimal secondary boosting start time, optimal secondary boosting platform pressure, and optimal secondary boosting duration, and form the optimal secondary boosting parameters. Perform pressure change rate constraint correction and boundary correction on the optimal secondary boosting parameters.

[0013] The pressure setting command sequence is generated based on the corrected optimal secondary boosting parameters and sent to the hydraulic system for execution. At the same time, the pressure setting command sequence is stored.

[0014] Optionally, the step of setting a punch displacement sensor and a liquid forging pressure sensor to synchronously acquire displacement voltage signals and pressure voltage signals according to a sampling period, completing calibration and zero-point correction, and generating a punch displacement sampling sequence and a liquid forging pressure sampling sequence specifically includes:

[0015] A displacement sensor is set in the direction of the punch movement in the liquid forging equipment to collect the original voltage signal corresponding to the punch displacement. The voltage discrete sequence of the displacement sensor is formed by sequentially collecting the data at a fixed sampling period through a data acquisition device, and each sampling point is assigned an index number that increases in time sequence.

[0016] A pressure sensor is set in the liquid forging pressure channel to collect the original voltage signal corresponding to the liquid forging pressure. The voltage discrete sequence of the pressure sensor is synchronously collected by the data acquisition device at the same sampling period as the displacement sampling, and each sampling point is assigned a consistent index number corresponding to the displacement sampling.

[0017] Select the first and second sets of standard displacement values ​​for displacement calibration, obtain the voltage readings output by the displacement sensor under the two sets of standard displacement values, obtain the proportional coefficient of displacement to voltage by the ratio of the difference between the two sets of standard displacement values ​​to the difference between the two sets of voltage readings, and obtain the displacement calibration intercept by subtracting the product of the proportional coefficient and the first set of voltage readings from the first set of standard displacement values.

[0018] For each sampling point of the displacement sensor, the voltage reading of each sampling point is multiplied by the displacement-voltage ratio coefficient, and the displacement calibration intercept is added to obtain the punch displacement value corresponding to each sampling point, forming a discrete sequence of punch displacement.

[0019] Select the first and second sets of standard pressure values ​​for pressure calibration, obtain the voltage readings output by the pressure sensor under the two sets of standard pressure values, obtain the pressure-voltage proportionality coefficient by the ratio of the difference between the two sets of standard pressure values ​​to the difference between the two sets of voltage readings, and obtain the pressure calibration intercept by subtracting the product of the proportionality coefficient and the first set of voltage readings from the first set of standard pressure values.

[0020] For each sampling point of the pressure sensor, the voltage reading of each sampling point is multiplied by the pressure-voltage ratio coefficient, and then the pressure calibration intercept is added to obtain the liquid forging pressure value corresponding to each sampling point, forming a discrete sequence of liquid forging pressure.

[0021] Before the injection begins, a synchronous sampling is performed to obtain the punch displacement value and liquid forging pressure value at the initial sampling point;

[0022] For all sampling points, subtract the initial sampling point's punch displacement value from the punch displacement value of each sampling point and update it with the corrected punch displacement value. At the same time, subtract the initial sampling point's liquid forging pressure value from the liquid forging pressure value of each sampling point and update it with the corrected liquid forging pressure value.

[0023] Optionally, the step of calculating the displacement change rate sequence and pressure change rate sequence based on the punch displacement sampling sequence and the liquid forging pressure sampling sequence, and constructing an effective compensation displacement increment sequence according to the displacement increment, specifically includes:

[0024] Based on the discrete sequence of punch displacement obtained at a fixed sampling period, for each sampling interval except the initial sampling point, the punch displacement value of the next sampling point in each sampling interval is obtained by subtracting the punch displacement value of the previous sampling point, and the difference between the punch displacement value of the next sampling point and the punch displacement value of the previous sampling point is divided by the sampling period to obtain the average displacement change rate in each sampling interval, thus forming a displacement change rate sequence.

[0025] Based on the discrete sequence of liquid forging pressure obtained at a fixed sampling period, for each sampling interval except the initial sampling point, the liquid forging pressure value of the next sampling point in each sampling interval is obtained by subtracting the liquid forging pressure value of the previous sampling point, and the difference between the liquid forging pressure value of the next sampling point and the liquid forging pressure value of the previous sampling point is divided by the sampling period to obtain the average pressure change rate in each sampling interval, thus forming a pressure change rate sequence.

[0026] For each sampling interval, when the punch displacement value of the next sampling point in each sampling interval is greater than the punch displacement value of the previous sampling point, the difference between the punch displacement value of the next sampling point and the punch displacement value of the previous sampling point is taken as the effective compensation displacement increment of the current sampling interval. When the punch displacement value of the next sampling point in each sampling interval is not greater than the punch displacement value of the previous sampling point, the effective compensation displacement increment of the current sampling interval is recorded as zero, forming an effective compensation displacement increment sequence.

[0027] Optionally, the step of obtaining the filling end sampling interval and the shrinkage evaluation termination sampling interval based on the statistical thresholds of the displacement change rate sequence and the pressure change rate sequence to form the shrinkage evaluation time interval specifically includes:

[0028] The displacement change velocity sequences of all sampling intervals are statistically analyzed, and the displacement change velocity sequences are sorted from smallest to largest. The value at which the cumulative probability is 95% is used as the 95th percentile threshold of the displacement change velocity.

[0029] In all sampling intervals except the last one, select a set of sampling interval indices that satisfy the condition that the displacement change rate of the current sampling interval is not greater than the 95th percentile threshold of the displacement change rate and the displacement change rate of the next sampling interval is not greater than the 95th percentile threshold of the displacement change rate. When the index set is not empty, select the sampling interval with the smallest index from the index set as the filling end sampling interval. When the index set is empty, select the second to last sampling interval as the filling end sampling interval.

[0030] The continuous time corresponding to the end of filling is obtained by multiplying the index of the sampling interval at the end of filling with the sampling period.

[0031] The absolute values ​​of the pressure change rate sequence in all sampling intervals are statistically analyzed. The absolute values ​​of the pressure change rate sequence are sorted from smallest to largest. The value at the point with a cumulative probability of 5% is used as the 5% quantile threshold of the absolute value of the pressure change rate.

[0032] After the filling end sampling interval and in all sampling intervals except the last sampling interval, select the sampling interval index set that satisfies the condition that the absolute value of the pressure change rate of this sampling interval is not greater than the 5th percentile threshold of the absolute value of the pressure change rate and the absolute value of the pressure change rate of the subsequent sampling interval is not greater than the 5th percentile threshold of the absolute value of the pressure change rate. When the index set is not empty, select the sampling interval with the smallest index from the index set as the termination sampling interval for the compensation evaluation. When the index set is empty, use the last sampling interval as the termination sampling interval for the compensation evaluation.

[0033] Based on the product of the index of the termination sampling interval of the compensation assessment and the sampling period, the continuous time corresponding to the termination time of the compensation assessment is obtained, and the time interval between the end sampling interval of the filling end and the termination sampling interval of the compensation assessment is taken as the compensation assessment time interval.

[0034] Optionally, the step of accumulating the effective shrinkage displacement increments within the shrinkage assessment time interval to obtain the total effective shrinkage displacement, integrating the liquid forging pressure over time to obtain the pressure area, and constructing a smoothness index based on the total effective shrinkage displacement and the pressure area specifically includes:

[0035] Within the time interval of the compensation assessment, the effective compensation displacement increments of each sampling interval are added one by one to obtain the total effective compensation displacement within the time interval of the compensation assessment.

[0036] Within the shrinkage assessment time interval, the product of the liquid forging pressure value and the sampling period for each sampling interval is added one by one to obtain the pressure area within the shrinkage assessment time interval, which is the integral result of the liquid forging pressure over time within the shrinkage assessment time interval.

[0037] When the pressure area during the compensation assessment time interval is greater than zero, the total effective compensation displacement is divided by the pressure area to obtain the baseline smoothness index of the wheel hub compensation channel without secondary pressurization. When the pressure area is not greater than zero, the baseline smoothness index is set to zero.

[0038] Optionally, the setting of the secondary boost start time, secondary boost platform pressure, and secondary boost duration as secondary boost decision variables, and the discrete generation of a secondary boost candidate parameter set within an allowable range, specifically includes:

[0039] The secondary boosting start time, secondary boosting platform pressure, and secondary boosting duration are set as secondary boosting decision variables. The lower limit and upper limit of the secondary boosting start time are set for the secondary boosting start time, the lower limit and upper limit of the secondary boosting platform pressure are set for the secondary boosting platform pressure, and the lower limit and upper limit of the secondary boosting duration are set for the secondary boosting duration.

[0040] Based on the end time of filling, the start time of secondary boosting is discretized after the end time of filling by an integer multiple of the sampling period to obtain a set of possible candidate values ​​for the start time of secondary boosting, which are limited to the lower limit and the upper limit of the start time of secondary boosting.

[0041] Using the sampling period as the unit, the duration of secondary boost is expressed as a positive integer multiple of the sampling period, resulting in a set of possible candidate values ​​for the duration of secondary boost, which are limited to the lower limit and the upper limit of the duration of secondary boost.

[0042] Using a preset pressure setting resolution as the step size, starting from the lower limit of the secondary pressurization platform pressure allowed by the process, gradually increase to obtain a set of candidate pressure values ​​for the secondary pressurization platform, and limit them between the lower limit and the upper limit of the secondary pressurization platform pressure allowed by the process.

[0043] By combining candidate values ​​for the start time of secondary boosting, candidate values ​​for the pressure of the secondary boosting platform, and candidate values ​​for the duration of secondary boosting, a triplet of secondary boosting parameters that simultaneously satisfies the constraints of the range of values ​​for the start time of secondary boosting, the range of values ​​for the pressure of the secondary boosting platform, and the range of values ​​for the duration of secondary boosting is selected, thus forming a set of candidate secondary boosting parameters.

[0044] When the set of secondary boosting candidate parameters is empty, the lower limit of the secondary boosting start time and the upper limit of the secondary boosting start time are added together and divided by two to obtain the intermediate value as the secondary boosting start time. The lower limit of the secondary boosting platform pressure allowed by the process and the upper limit of the secondary boosting platform pressure allowed by the process are added together and divided by two to obtain the intermediate value as the secondary boosting platform pressure. The lower limit of the secondary boosting duration and the upper limit of the secondary boosting duration are added together and divided by two to obtain the intermediate value as the secondary boosting duration. The secondary boosting parameter triple consisting of the three sets of intermediate values ​​is added to the secondary boosting candidate parameter set as the unique element.

[0045] Optionally, the step of constructing a secondary boost target pressure trajectory that satisfies the pressure change rate constraint for each set of parameters in the secondary boost candidate parameter set, forming a pressure target sequence, and calculating the corresponding smoothness index based on the pressure target sequence within the compensation evaluation time interval, specifically includes:

[0046] For each triplet of secondary boost parameters in the candidate set of secondary boost parameters, the sampling point that is closest to the start time of secondary boost and is within the allowed index range is selected as the start sampling point of secondary boost based on the ratio of the start time of secondary boost to the sampling period in the triplet of secondary boost parameters.

[0047] Obtain the original liquid forging pressure value instant before the start of secondary pressurization, calculate the difference between the secondary pressurization platform pressure and the original liquid forging pressure value, and divide the absolute value of the pressure difference between the secondary pressurization platform pressure and the original liquid forging pressure value by the maximum pressure change rate allowed by the equipment to obtain the candidate pressure rise time required to transition from the original liquid forging pressure value to the secondary pressurization platform pressure under the upper limit constraint of the pressure change rate.

[0048] When the duration of the secondary boost is not less than the candidate pressure rise time, the candidate pressure rise time is taken as the actual pressure rise time. When the duration of the secondary boost is less than the candidate pressure rise time, the duration of the secondary boost is taken as the actual pressure rise time. The end time of the secondary boost rise segment is obtained by summing the start time of the secondary boost and the actual pressure rise time. The end time of the secondary boost platform holding segment is obtained by summing the start time of the secondary boost and the duration of the secondary boost.

[0049] When the actual pressure rise time is greater than zero, the original liquid forging pressure curve is maintained for all moments before the start of the secondary pressurization. From the start of the secondary pressurization to the end of the secondary pressurization rise segment, a linear interpolation is performed between the original liquid forging pressure value and the secondary pressurization platform pressure instantaneously before the start of the secondary pressurization. From the end of the secondary pressurization rise segment to the end of the secondary pressurization platform holding segment, the secondary pressurization platform pressure is maintained. After the end of the secondary pressurization platform holding segment, the original liquid forging pressure curve is restored. When the actual pressure rise time is equal to zero, the original liquid forging pressure curve is maintained before the start of the secondary pressurization. From the start of the secondary pressurization to the end of the secondary pressurization platform holding segment, the secondary pressurization platform pressure is maintained. After the end of the secondary pressurization platform holding segment, the original liquid forging pressure curve is restored. This yields the secondary pressurization target pressure trajectory over the entire time axis.

[0050] At all sampling times, the secondary pressurization target pressure trajectory corresponding to each sampling time is sampled to obtain the liquid forging pressure target sequence under the condition of applying secondary pressurization control.

[0051] Within the compensation assessment time interval, for each sampling interval, the secondary boosting pressure target value of each sampling interval is obtained by subtracting the original liquid forging pressure value and multiplying by the sampling period to obtain the additional pressure area increment of each sampling interval.

[0052] When the pressure area within the compensation assessment time interval is greater than zero without secondary pressurization, the total effective compensation displacement within the compensation assessment time interval is divided by the pressure area to obtain the effective compensation displacement per unit pressure area. The additional pressure area increment of each sampling interval is multiplied by the effective compensation displacement per unit pressure area to obtain the alternative effective compensation displacement converted from the additional pressure input for each sampling interval. This alternative effective compensation displacement increment is then added to the original effective compensation displacement increment of each sampling interval to obtain the alternative effective compensation displacement increment for each sampling interval. When the pressure area within the compensation assessment time interval is not greater than zero without secondary pressurization, the alternative effective compensation displacement increment for each sampling interval is recorded as the original effective compensation displacement increment for each sampling interval.

[0053] Within the compensation evaluation time interval, the parts of the alternative effective compensation displacement increments in all sampling intervals that are less than zero are treated as zero and then summed to obtain the total alternative effective compensation displacement corresponding to each secondary boosting parameter triplet.

[0054] Within the compensation assessment time interval, the product of the secondary boost pressure target value and the sampling period for all sampling intervals is added one by one to obtain the pressure input area corresponding to each secondary boost parameter triplet. When the pressure input area is greater than zero, the total effective compensation displacement is divided by the pressure input area to obtain the compensation channel smoothness index corresponding to each secondary boost parameter triplet. When the pressure input area is not greater than zero, the compensation smoothness index corresponding to each secondary boost parameter triplet is set to zero.

[0055] Optionally, the step of selecting the parameter group with the largest smoothness index from the secondary boost candidate parameter set, obtaining the optimal secondary boost start time, optimal secondary boost platform pressure, and optimal secondary boost duration, and forming the optimal secondary boost parameters, and performing pressure change rate constraint correction and boundary correction on the optimal secondary boost parameters, specifically includes:

[0056] In the set of secondary boosting candidate parameters, the secondary boosting pressure curve and alternative smoothness calculation steps are called for each secondary boosting parameter triplet to obtain the corresponding compensation channel smoothness index, and the smoothness value with the largest smoothness index is selected as the maximum smoothness value among all candidates.

[0057] In the set of candidate secondary boost parameters, all triplet parameters of secondary boost parameters whose compensation channel smoothness index is equal to the maximum smoothness value are selected to form the maximum smoothness parameter set.

[0058] In the maximum smoothness parameter set, the parameter triplet with the smallest secondary boost start time is selected first. When there are multiple parameter triplets with the same secondary boost start time, the parameter triplet with the smaller secondary boost platform pressure is selected from these parameter triplets. When there are still multiple parameter triplets, the parameter triplet with the smaller secondary boost duration is selected from these parameter triplets to obtain the optimal secondary boost start time, optimal secondary boost platform pressure, and optimal secondary boost duration.

[0059] By substituting the optimal secondary boost parameters into the secondary boost pressure curve and the secondary boost target pressure trajectory construction process in the alternative smoothness calculation, the optimal secondary boost pressure target sequence over the entire sampling time axis is obtained.

[0060] In the optimal secondary boost pressure target sequence, for each sampling interval except the initial sampling point, the optimal secondary boost pressure target value of the next sampling point in each sampling interval is calculated by subtracting the optimal secondary boost pressure target value of the previous sampling point from the optimal secondary boost pressure target value of the next sampling point. The difference between the optimal secondary boost pressure target value of the next sampling point and the optimal secondary boost pressure target value of the previous sampling point is divided by the sampling period to obtain the discrete pressure change rate of each sampling interval. The maximum discrete pressure change rate is selected from all sampling intervals as the maximum discrete pressure change rate in the optimal secondary boost pressure target sequence.

[0061] When the maximum discrete pressure change rate on the optimal secondary boosting pressure target sequence is not greater than the maximum pressure change rate allowed by the equipment, the optimal secondary boosting platform pressure is kept constant and used as the corrected optimal secondary boosting platform pressure. When the maximum discrete pressure change rate on the optimal secondary boosting pressure target sequence is greater than the maximum pressure change rate allowed by the equipment, the original liquid forging pressure value is obtained instantaneously before the start of the optimal secondary boosting. The product of the maximum pressure change rate allowed by the equipment and the duration of the optimal secondary boosting is used as the maximum allowable pressure increment. When the optimal secondary boosting platform pressure is higher than the original liquid forging pressure value, the maximum allowable pressure increment is added to the original liquid forging pressure value to obtain the corrected optimal secondary boosting platform pressure. When the optimal secondary boosting platform pressure is lower than the original liquid forging pressure value, the maximum allowable pressure increment is subtracted from the original liquid forging pressure value to obtain the corrected optimal secondary boosting platform pressure. When the optimal secondary boosting platform pressure is equal to the original liquid forging pressure value, the original liquid forging pressure value is used as the corrected optimal secondary boosting platform pressure.

[0062] The optimal secondary boost start time is used as the corrected optimal secondary boost start time. When the corrected optimal secondary boost start time is less than the lower limit of the secondary boost start time, the corrected optimal secondary boost start time is set as the lower limit of the secondary boost start time. When the corrected optimal secondary boost start time is greater than the upper limit of the secondary boost start time, the corrected optimal secondary boost start time is set as the upper limit of the secondary boost start time.

[0063] When the corrected optimal secondary booster platform pressure is less than the lower limit of the secondary booster platform pressure allowed by the process, the corrected optimal secondary booster platform pressure is set to the lower limit of the secondary booster platform pressure allowed by the process. When the corrected optimal secondary booster platform pressure is greater than the upper limit of the secondary booster platform pressure allowed by the process, the corrected optimal secondary booster platform pressure is set to the upper limit of the secondary booster platform pressure allowed by the process.

[0064] The optimal secondary boost duration is used as the corrected optimal secondary boost duration. When the corrected optimal secondary boost duration is less than the lower limit of the secondary boost duration, the corrected optimal secondary boost duration is set as the lower limit of the secondary boost duration. When the corrected optimal secondary boost duration is greater than the upper limit of the secondary boost duration, the corrected optimal secondary boost duration is set as the upper limit of the secondary boost duration.

[0065] Optionally, the step of generating a pressure setting command sequence based on the corrected optimal secondary boosting parameters and sending it to the hydraulic system for execution, while storing the pressure setting command sequence, specifically includes: forming an optimal secondary boosting parameter set by combining the corrected optimal secondary boosting start time, the corrected optimal secondary boosting platform pressure, and the corrected optimal secondary boosting duration.

[0066] Substituting the optimal set of secondary boosting parameters into the secondary boosting pressure curve and the secondary boosting target pressure trajectory construction process in the alternative smoothness calculation, the optimal secondary boosting target pressure trajectory covering the entire liquid forging process is generated under the condition of satisfying the pressure change rate constraint.

[0067] At all sampling times, the optimal secondary pressurization target pressure trajectory is sampled, and the pressure setpoint corresponding to each sampling time is obtained. The pressure setpoint is then arranged in the order of the sampling times to form a pressure setpoint instruction sequence.

[0068] Based on the optimal set of secondary boost parameters, the actual pressure rise time under the optimal set of secondary boost parameters is calculated according to the actual pressure rise time calculation method in the secondary boost pressure curve and the substitution smoothness calculation. The sum of the corrected optimal secondary boost start time and the actual pressure rise time is divided by the sampling period to obtain the sampling index corresponding to the end time of the secondary boost rise segment. When the calculated sampling index is greater than the last sampling index, the calculated sampling index is set as the last sampling index.

[0069] Based on the optimal secondary boost parameter set, calculate the sum of the corrected optimal secondary boost start time and the corrected optimal secondary boost duration, divide by the sampling period, and obtain the sampling index corresponding to the end time of the secondary boost platform holding segment. When the calculated sampling index is greater than the last sampling index, set the calculated sampling index as the last sampling index.

[0070] The pressure setting command sequence is sent to the hydraulic system in the sampling order to perform secondary pressure boosting control, and the pressure setting command sequence is stored and solidified.

[0071] The present invention has the following beneficial effects:

[0072] 1. By uniformly deploying punch displacement sensors and liquid forging pressure sensors, and synchronously acquiring displacement and pressure voltage signals according to a fixed sampling period, combined with dual-point calibration and zero-point correction, the raw voltage signals are converted into time-aligned discrete sequences of displacement and pressure. Unlike existing technologies that commonly monitor only pressure or only displacement, or where two sensors record independently and are roughly aligned later, this method ensures a one-to-one correspondence between the displacement and pressure sequences on the time axis from the data source, avoiding information distortion caused by manual interpolation and alignment in the post-processing stage. By performing synchronous sampling and zero-point correction before injection, the influence of equipment installation errors, initial gaps, and sensor zero drift on subsequent analysis is eliminated, ensuring that the displacement increment and pressure change rate calculated later are all based on the injection start point as a unified reference.

[0073] 2. After obtaining the time-aligned displacement and pressure sequences, instead of directly using the original curves, the displacement change rate and pressure change rate are calculated based on adjacent sampling points. An effective compensation displacement increment sequence is constructed by retaining only the increased displacement. This scheme introduces derivative thinking: displacement velocity reflects the instantaneous intensity of the punch propulsion and metal flow, while the pressure change rate reflects the rate of change of force within the liquid metal. Combining these two factors can distinguish between normal filling, stable compensation, and possible springback or stagnation. By checking for displacement increases in each sampling interval and setting non-positive displacement changes to zero, the scheme retains only the displacement increments that truly contribute to the metal's replenishment of the cavity's contraction channel, thus eliminating interference factors such as mechanical vibration and springback. The innovation of this approach lies in using discrete increments to characterize the compensation behavior, making the subsequent calculation of the total effective compensation displacement closer to the actual metal compensation, rather than simply accumulating displacement differences.

[0074] 3. By statistically analyzing the displacement rate change sequence and pressure rate change sequence, the system automatically identifies the sampling interval for the end of filling and the sampling interval for the termination of shrinkage assessment using high and low quantile thresholds, thus constructing an assessment time interval specifically for shrinkage behavior. Compared to traditional methods that rely on empirical time, fixed punch stroke position, or manual observation of pressure inflection points to determine the end of filling, this solution introduces a statistically driven adaptive judgment mechanism: when the overall displacement velocity drops below the preset high quantile threshold and continuously meets the conditions, filling is considered basically complete; when the absolute value of the pressure rate change during the shrinkage stage drops to the low quantile threshold and remains there for a relatively long time, the shrinkage behavior is considered to have entered a stable state, and the shrinkage assessment can be terminated. This processing can automatically adapt to the filling and shrinkage rhythms of different molds, different alloys, and different pouring temperatures, eliminating the need for operators to re-estimate the end time each time.

[0075] 4. Within the feeding assessment time interval, the effective feeding displacement increments are accumulated to obtain the total effective feeding displacement. Simultaneously, the pressure is integrated over time to obtain the pressure area, and a feeding channel unobstructedness index is constructed based on the relationship between the two. Traditional liquid forging processes often evaluate feeding effectiveness using endpoint defect inspections, one-time trial results, or isolated pressure peak indicators. It is difficult to use a comprehensive quantity to reflect the metal feeding capacity corresponding to a unit pressure input throughout the entire feeding stage. By quantifying the metal feeding effect through the total effective feeding displacement and the pressure resource input through the pressure area, and then using the ratio of the two to characterize the unobstructedness of the feeding channel, a unified standard for comparing different process conditions is obtained. In real-world problems, simply increasing the pressure may lead to excessive mold stress and excessive equipment load, while the feeding effect may not necessarily improve linearly. The unobstructedness index can identify process windows with better feeding effects under relatively reasonable pressure input.

[0076] 5. The secondary boosting start time, secondary boosting platform pressure, and secondary boosting duration are explicitly defined as decision variables. These variables are discretized under constraints of equipment capacity and process boundaries, forming a set of candidate parameters for secondary boosting. This scheme treats the secondary boosting process as a three-dimensional parameter space, systematically meshing feasible secondary boosting schemes to form a finite number of candidate triples. By setting the ranges for the start time, platform pressure, and duration, different mold structures and wheel hub geometries can be flexibly adapted, while avoiding dangerous parameters that violate the equipment's maximum pressure or maximum stroke speed. First, the previously fuzzy process parameter adjustments are transformed into a systematic search basis covering the entire feasible space, providing a search domain for subsequent optimal algorithms. Second, by automatically generating candidate triples with centered parameters when the candidate set is empty, the algorithm ensures that it can still provide reasonable secondary boosting schemes under extreme constraints, enhancing its practicality and robustness. Third, this discretization design reserves a structured interface for future introduction of more constraints or scoring dimensions (such as energy consumption and cycle time), facilitating expansion.

[0077] 6. For each set of secondary pressurization parameters in the candidate set, a target pressure trajectory that satisfies the equipment's allowable pressure change rate constraint is constructed, generating a corresponding pressure target sequence. Within the compensation evaluation time interval, the substitution contribution of additional pressure input to the effective compensation displacement is calculated, thus obtaining the compensation smoothness under each candidate scheme. This scheme limits the pressure rise rate, allowing the pressure to smoothly transition from the original level to the platform pressure. Simultaneously, the original pressure curve is restored after the platform holding period, ensuring that the target trajectory is more friendly to the equipment and mold throughout the entire cycle. More importantly, the algorithm not only considers the original effective compensation displacement but also converts the additional pressure input into an equivalent compensation displacement increment, which is then superimposed on the original compensation displacement to obtain a more comprehensive substitution of the effective compensation displacement. This allows for a direct observation of whether the compensation effect is significantly improved under a certain additional pressure area input, thus avoiding excessive equipment burden and energy consumption for minor improvements. Furthermore, by truncating negative substitution displacements, the excessive influence of abnormal pressure trajectories on the evaluation results is avoided, making the evaluation more stable and reliable.

[0078] 7. In the set of candidate parameters for secondary pressurization, the candidate scheme with the highest smoothness is selected based on the smoothness of the compensation channel corresponding to each set of parameters. A unique optimal secondary pressurization start time, platform pressure, and duration are determined through a set of ordered sorting rules. Then, the optimal secondary pressurization parameters are substituted into the pressure trajectory construction process to calculate the actual discrete pressure change rate. For cases where the pressure change rate is too large, platform pressure correction is performed, and further boundary projection corrections are applied to the start time, platform pressure, and duration. Compared to selecting a seemingly reasonable set of secondary pressurization parameters based solely on engineering experience, this scheme introduces clear optimization objectives and decision rules: prioritizing maximum smoothness, followed by an earlier start time, then a lower platform pressure, and finally a shorter duration. This ensures both compensation effect and process efficiency and equipment load. Based on this, pressure change rate checks and corrections are performed to ensure that the optimal scheme will not cause excessive impact on the hydraulic system and mold during actual execution. Boundary projection ensures that the final parameters strictly fall within the preset safety range.

[0079] 8. Utilizing the corrected optimal secondary pressurization parameters, an optimal secondary pressurization target pressure trajectory covering the entire liquid forging process is generated within the existing secondary pressurization pressure trajectory construction framework. Pressure setting command sequences are obtained by sampling the trajectory at all sampling moments and sent to the hydraulic system for execution in chronological order. Simultaneously, this sequence is stored and solidified. Unlike existing technologies that commonly rely on manual input of a few key points or the invocation of fixed template curves on the control interface, this solution provides pressure commands that are automatically generated from sensor data, after compensation evaluation and parameter optimization, resulting in customized curves for specific die stages or die states. The command sequence has a time resolution at the sampling period level, allowing for fine-grained description of the secondary pressurization rise phase, the plateau holding phase, and the entire process of restoring the original pressure. This facilitates comparison with actual sampled data and allows for subsequent offline analysis using historical samples. Attached Figure Description

[0080] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0081] 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, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0082] Example, refer to Figure 1 An optimized control method for a wheel hub liquid forging process includes:

[0083] Set up a punch displacement sensor and a liquid forging pressure sensor, synchronously collect displacement voltage signals and pressure voltage signals according to the sampling period, complete calibration and zero point correction, and generate punch displacement sampling sequence and liquid forging pressure sampling sequence;

[0084] The displacement change rate sequence and pressure change rate sequence are calculated based on the punch displacement sampling sequence and the liquid forging pressure sampling sequence, and an effective compensation displacement increment sequence is constructed according to the displacement increment.

[0085] Based on the statistical thresholds of the displacement change rate sequence and the pressure change rate sequence, the filling end sampling interval and the shrinkage evaluation termination sampling interval are obtained, forming the shrinkage evaluation time interval;

[0086] The total effective shrinkage displacement is obtained by accumulating the effective shrinkage displacement increment within the shrinkage assessment time interval. The pressure area is obtained by integrating the liquid forging pressure over time. A smoothness index is constructed based on the total effective shrinkage displacement and the pressure area.

[0087] Set the start time of secondary boost, the pressure of the secondary boost platform, and the duration of secondary boost as decision variables for secondary boost, and generate a set of candidate parameters for secondary boost discretization within the allowable range;

[0088] For each set of parameters in the secondary boost candidate parameter set, construct a secondary boost target pressure trajectory that satisfies the pressure change rate constraint, form a pressure target sequence, and calculate the corresponding smoothness index based on the pressure target sequence within the compensation evaluation time interval;

[0089] Select the parameter group with the highest smoothness index from the set of secondary boosting candidate parameters, obtain the optimal secondary boosting start time, optimal secondary boosting platform pressure, and optimal secondary boosting duration, and form the optimal secondary boosting parameters. Perform pressure change rate constraint correction and boundary correction on the optimal secondary boosting parameters.

[0090] The pressure setting command sequence is generated based on the corrected optimal secondary boosting parameters and sent to the hydraulic system for execution. At the same time, the pressure setting command sequence is stored.

[0091] By setting up a punch displacement sensor and a liquid forging pressure sensor, displacement and pressure signals are synchronously collected at a unified sampling period, and calibration and zero-point correction are performed. This solves the problems of inconsistent displacement and pressure data sources, misaligned time axes, and inconsistent dimensions in existing technologies, providing a reliable data foundation for subsequent calculations. By calculating the displacement change rate, pressure change rate, and effective compensation displacement increment based on unified data, the problem of not being able to accurately identify the actual metal compensation behavior by only looking at the original curve is solved. By automatically identifying the end of filling and the termination interval of compensation evaluation using statistical thresholds, the problem of relying on manual experience to select time periods and inconsistent judgments among different operators is solved. By calculating the total effective compensation displacement and pressure area within the compensation evaluation time and constructing a smoothness index, the problem of not being able to evaluate the smoothness of the compensation channel with a single quantitative parameter is solved. Furthermore, by constructing a candidate set using the start time of secondary pressurization, platform pressure, and duration as decision variables, and generating target pressure trajectories that meet the pressure change rate constraint one by one, calculating the smoothness corresponding to each candidate, and selecting the optimal parameters, the problem of relying on experience to adjust secondary pressurization parameters and lacking system optimization and evaluation mechanisms is solved. Finally, by generating a pressure setting command sequence based on the optimal parameters and directly issuing it to the hydraulic system, the problem of the optimization results being difficult to stably implement was solved.

[0092] The process involves setting up a punch displacement sensor and a liquid forging pressure sensor to synchronously acquire displacement voltage signals and pressure voltage signals according to a sampling period, completing calibration and zero-point correction, and generating punch displacement sampling sequences and liquid forging pressure sampling sequences. Specifically, this includes:

[0093] A displacement sensor is set in the direction of the punch movement in the liquid forging equipment to collect the original voltage signal corresponding to the punch displacement. The voltage discrete sequence of the displacement sensor is formed by sequentially collecting the data at a fixed sampling period through a data acquisition device, and each sampling point is assigned an index number that increases in time sequence.

[0094] A pressure sensor is set in the liquid forging pressure channel to collect the original voltage signal corresponding to the liquid forging pressure. The voltage discrete sequence of the pressure sensor is synchronously collected by the data acquisition device at the same sampling period as the displacement sampling, and each sampling point is assigned a consistent index number corresponding to the displacement sampling.

[0095] Select the first and second sets of standard displacement values ​​for displacement calibration, obtain the voltage readings output by the displacement sensor under the two sets of standard displacement values, obtain the proportional coefficient of displacement to voltage by the ratio of the difference between the two sets of standard displacement values ​​to the difference between the two sets of voltage readings, and obtain the displacement calibration intercept by subtracting the product of the proportional coefficient and the first set of voltage readings from the first set of standard displacement values.

[0096] For each sampling point of the displacement sensor, the voltage reading of each sampling point is multiplied by the displacement-voltage ratio coefficient, and the displacement calibration intercept is added to obtain the punch displacement value corresponding to each sampling point, forming a discrete sequence of punch displacement.

[0097] Select the first and second sets of standard pressure values ​​for pressure calibration, obtain the voltage readings output by the pressure sensor under the two sets of standard pressure values, obtain the pressure-voltage proportionality coefficient by the ratio of the difference between the two sets of standard pressure values ​​to the difference between the two sets of voltage readings, and obtain the pressure calibration intercept by subtracting the product of the proportionality coefficient and the first set of voltage readings from the first set of standard pressure values.

[0098] For each sampling point of the pressure sensor, the voltage reading of each sampling point is multiplied by the pressure-voltage ratio coefficient, and then the pressure calibration intercept is added to obtain the liquid forging pressure value corresponding to each sampling point, forming a discrete sequence of liquid forging pressure.

[0099] Before the injection begins, a synchronous sampling is performed to obtain the punch displacement value and liquid forging pressure value at the initial sampling point;

[0100] For all sampling points, subtract the initial sampling point's punch displacement value from the punch displacement value of each sampling point and update it with the corrected punch displacement value. At the same time, subtract the initial sampling point's liquid forging pressure value from the liquid forging pressure value of each sampling point and update it with the corrected liquid forging pressure value.

[0101] A displacement sensor is installed in the direction of the punch movement in the liquid forging equipment to output the original voltage signal. ;in, For continuous time variables; For continuous time intervals The original voltage signal output by the punch displacement sensor;

[0102] Using data acquisition equipment at sampling period right Perform synchronous sampling to obtain a discrete sequence. ;in, For the first Each sampling time; The index number of the sampling point; This is the maximum sampling index collected during this liquid forging process; In the first The voltage value of the punch displacement sensor measured at each sampling time;

[0103] A pressure sensor is installed in the liquid forging pressure channel to output the original voltage signal. ;in, For continuous time intervals The original voltage signal output by the pressure sensor;

[0104] By sampling the data acquisition device at the sampling period right Perform synchronous sampling to obtain a discrete sequence. ;in, In the first The pressure value of the pressure sensor was measured at each sampling time.

[0105] Select two points to mark and move. , The corresponding sensor voltage reading is , ,and ;in, , These are the first set of standard displacement values ​​and the second set of displacement values ​​used for displacement calibration, respectively. , They are respectively at the first group of displacement calibration points Second set of displacement calibration points The displacement sensor voltage value measured below;

[0106] The displacement calibration coefficients are constructed as follows: , ;in, This is the displacement-to-voltage proportionality coefficient of the displacement sensor; The calibration intercept of the displacement sensor;

[0107] At any sampling time The displacement value is calculated as follows: ;in, In the first Each sampling time The corresponding punch displacement value;

[0108] Select two points to calibrate pressure , The corresponding sensor voltage reading is , ;in, , These are the first set of standard pressure values ​​and the second set of standard pressure values ​​used for pressure calibration, respectively. , They are respectively at the first group of pressure calibration points Second group of pressure calibration points The voltage value of the pressure sensor measured below;

[0109] The pressure calibration coefficient is: , ;in, This is the pressure-voltage proportionality coefficient of the pressure sensor. The calibration intercept of the pressure sensor;

[0110] At any sampling time The pressure value is calculated as follows: ;in, In the first Each sampling time The corresponding liquid forging pressure value;

[0111] A sample is taken before the injection begins, and the sampling index is set to [index value]. ,Record , ;in, To the initial sampling point Displacement value at; To the initial sampling point Pressure value at the location;

[0112] Zero-point correction is performed on all sampling points, specifically as follows:

[0113] , , ;in, This is the assignment operator.

[0114] The calculation of the displacement change rate sequence and pressure change rate sequence based on the punch displacement sampling sequence and the liquid forging pressure sampling sequence, and the construction of an effective compensation displacement increment sequence according to the displacement increment, specifically includes:

[0115] Based on the discrete sequence of punch displacement obtained at a fixed sampling period, for each sampling interval except the initial sampling point, the punch displacement value of the next sampling point in each sampling interval is obtained by subtracting the punch displacement value of the previous sampling point, and the difference between the punch displacement value of the next sampling point and the punch displacement value of the previous sampling point is divided by the sampling period to obtain the average displacement change rate in each sampling interval, thus forming a displacement change rate sequence.

[0116] Based on the discrete sequence of liquid forging pressure obtained at a fixed sampling period, for each sampling interval except the initial sampling point, the liquid forging pressure value of the next sampling point in each sampling interval is obtained by subtracting the liquid forging pressure value of the previous sampling point, and the difference between the liquid forging pressure value of the next sampling point and the liquid forging pressure value of the previous sampling point is divided by the sampling period to obtain the average pressure change rate in each sampling interval, thus forming a pressure change rate sequence.

[0117] For each sampling interval, when the punch displacement value of the next sampling point in each sampling interval is greater than the punch displacement value of the previous sampling point, the difference between the punch displacement value of the next sampling point and the punch displacement value of the previous sampling point is taken as the effective compensation displacement increment of the current sampling interval. When the punch displacement value of the next sampling point in each sampling interval is not greater than the punch displacement value of the previous sampling point, the effective compensation displacement increment of the current sampling interval is recorded as zero, forming an effective compensation displacement increment sequence.

[0118] for The displacement velocity is calculated as follows: ;in, In the first The average displacement rate within each sampling interval;

[0119] for The rate of change of pressure is calculated as follows: ;in, In the first Average pressure change rate within each sampling interval;

[0120] for The single-step effective compensation displacement increment is constructed as follows:

[0121] ;in, For the first Effective compensation displacement increment within each sampling interval.

[0122] The method of obtaining the filling end sampling interval and the shrinkage evaluation termination sampling interval based on the statistical thresholds of the displacement change rate sequence and the pressure change rate sequence, forming the shrinkage evaluation time interval, specifically includes:

[0123] The displacement change velocity sequences of all sampling intervals are statistically analyzed, and the displacement change velocity sequences are sorted from smallest to largest. The value at which the cumulative probability is 95% is used as the 95th percentile threshold of the displacement change velocity.

[0124] In all sampling intervals except the last one, select a set of sampling interval indices that satisfy the condition that the displacement change rate of the current sampling interval is not greater than the 95th percentile threshold of the displacement change rate and the displacement change rate of the next sampling interval is not greater than the 95th percentile threshold of the displacement change rate. When the index set is not empty, select the sampling interval with the smallest index from the index set as the filling end sampling interval. When the index set is empty, select the second to last sampling interval as the filling end sampling interval.

[0125] The continuous time corresponding to the end of filling is obtained by multiplying the index of the sampling interval at the end of filling with the sampling period.

[0126] The absolute values ​​of the pressure change rate sequence in all sampling intervals are statistically analyzed. The absolute values ​​of the pressure change rate sequence are sorted from smallest to largest. The value at the point with a cumulative probability of 5% is used as the 5% quantile threshold of the absolute value of the pressure change rate.

[0127] After the filling end sampling interval and in all sampling intervals except the last sampling interval, select the sampling interval index set that satisfies the condition that the absolute value of the pressure change rate of this sampling interval is not greater than the 5th percentile threshold of the absolute value of the pressure change rate and the absolute value of the pressure change rate of the subsequent sampling interval is not greater than the 5th percentile threshold of the absolute value of the pressure change rate. When the index set is not empty, select the sampling interval with the smallest index from the index set as the termination sampling interval for the compensation evaluation. When the index set is empty, use the last sampling interval as the termination sampling interval for the compensation evaluation.

[0128] Based on the product of the index of the termination sampling interval of the compensation assessment and the sampling period, the continuous time corresponding to the termination time of the compensation assessment is obtained, and the time interval between the end sampling interval of the filling end and the termination sampling interval of the compensation assessment is taken as the compensation assessment time interval.

[0129] Calculate sequence of Quantiles are: ;in, To compute on the input real number sequence quantiles; For displacement velocity sequence quantiles;

[0130] Construct a candidate filling end sampling index set Specifically:

[0131] ;

[0132] like If not empty, then let: ;in, The sampling index at the end of the filling process;

[0133] like To control, then: ;

[0134] The continuous time at which the filling process ends is calculated as follows: ;

[0135] Calculate sequence of Quantiles are: ;in, To compute on the input sequence quantiles; For the absolute value sequence of pressure change rate quantiles;

[0136] Construct a candidate set of termination sampling indices for the compensation evaluation Specifically:

[0137] ;

[0138] like If not empty, then let: ;in, The sampling index is used to terminate the compensation assessment;

[0139] like If it is empty, then let: ;

[0140] The continuous time at which the compensation assessment terminates is calculated is: .

[0141] The process involves accumulating the effective shrinkage displacement increments within the shrinkage assessment time interval to obtain the total effective shrinkage displacement, integrating the liquid forging pressure over time to obtain the pressure area, and constructing a smoothness index based on the total effective shrinkage displacement and the pressure area. Specifically, this includes:

[0142] Within the time interval of the compensation assessment, the effective compensation displacement increments of each sampling interval are added one by one to obtain the total effective compensation displacement within the time interval of the compensation assessment.

[0143] Within the shrinkage assessment time interval, the product of the liquid forging pressure value and the sampling period for each sampling interval is added one by one to obtain the pressure area within the shrinkage assessment time interval, which is the integral result of the liquid forging pressure over time within the shrinkage assessment time interval.

[0144] When the pressure area during the compensation assessment time interval is greater than zero, the total effective compensation displacement is divided by the pressure area to obtain the baseline smoothness index of the wheel hub compensation channel without secondary pressurization. When the pressure area is not greater than zero, the baseline smoothness index is set to zero.

[0145] The effective compensation displacement is calculated as follows: ;in, This represents the total effective shrinkage displacement within the shrinkage assessment interval.

[0146] The pressure area during the feeding stage is calculated as follows: ;in, The pressure area is obtained by integrating the pressure over time within the compensation assessment time interval.

[0147] like The baseline smoothness of the compensation channel is then defined as follows: ;in, This serves as the baseline unobstructedness index for the wheel hub compression channel when no secondary pressurization is performed.

[0148] like Then let: .

[0149] The process of setting the start time of secondary boosting, the pressure of the secondary boosting platform, and the duration of secondary boosting as decision variables for secondary boosting, and discretizing and generating a set of candidate parameters for secondary boosting within an allowable range, specifically includes:

[0150] The secondary boosting start time, secondary boosting platform pressure, and secondary boosting duration are set as secondary boosting decision variables. The lower limit and upper limit of the secondary boosting start time are set for the secondary boosting start time, the lower limit and upper limit of the secondary boosting platform pressure are set for the secondary boosting platform pressure, and the lower limit and upper limit of the secondary boosting duration are set for the secondary boosting duration.

[0151] Based on the end time of filling, the start time of secondary boosting is discretized after the end time of filling by an integer multiple of the sampling period to obtain a set of possible candidate values ​​for the start time of secondary boosting, which are limited to the lower limit and the upper limit of the start time of secondary boosting.

[0152] Using the sampling period as the unit, the duration of secondary boost is expressed as a positive integer multiple of the sampling period, resulting in a set of possible candidate values ​​for the duration of secondary boost, which are limited to the lower limit and the upper limit of the duration of secondary boost.

[0153] Using a preset pressure setting resolution as the step size, starting from the lower limit of the secondary pressurization platform pressure allowed by the process, gradually increase to obtain a set of candidate pressure values ​​for the secondary pressurization platform, and limit them between the lower limit and the upper limit of the secondary pressurization platform pressure allowed by the process.

[0154] By combining candidate values ​​for the start time of secondary boosting, candidate values ​​for the pressure of the secondary boosting platform, and candidate values ​​for the duration of secondary boosting, a triplet of secondary boosting parameters that simultaneously satisfies the constraints of the range of values ​​for the start time of secondary boosting, the range of values ​​for the pressure of the secondary boosting platform, and the range of values ​​for the duration of secondary boosting is selected, thus forming a set of candidate secondary boosting parameters.

[0155] When the set of secondary boosting candidate parameters is empty, the lower limit of the secondary boosting start time and the upper limit of the secondary boosting start time are added together and divided by two to obtain the intermediate value as the secondary boosting start time. The lower limit of the secondary boosting platform pressure allowed by the process and the upper limit of the secondary boosting platform pressure allowed by the process are added together and divided by two to obtain the intermediate value as the secondary boosting platform pressure. The lower limit of the secondary boosting duration and the upper limit of the secondary boosting duration are added together and divided by two to obtain the intermediate value as the secondary boosting duration. The secondary boosting parameter triple consisting of the three sets of intermediate values ​​is added to the secondary boosting candidate parameter set as the unique element.

[0156] Construct the secondary boost decision vector as follows ;in, This marks the start of the second boost. The pressure setting value for the secondary booster platform; This refers to the total duration of the secondary boost.

[0157] S501. Setting the range of values ​​for decision variables:

[0158] , , ;in, , These are the lower and upper limits for the start of the secondary boost, respectively; , These are the lower and upper limits of the pressure allowed by the process, respectively. , These are the lower and upper limits of the duration of the secondary boost, respectively.

[0159] S502, Construction of Discrete Candidate Sets for Decision Variables:

[0160] Discretize the start time of the secondary boost as follows: , ;in, This is the integer offset used to discretize the start time of the secondary boost; It is a set of integers;

[0161] The duration of the secondary boost is discretized as follows: , ;in, A positive integer multiple of the discretization duration;

[0162] The pressure of the secondary booster platform is discretized as follows: , ;in, The integer number of steps used to discretize the pressure level; Set the resolution for pressure;

[0163] Construct the set of triplets for all alternative secondary boost parameters as follows: ,and To satisfy the combination of S501 and S502;

[0164] If set If it is empty, then let:

[0165] , , And add the triple as the unique element to the set. .

[0166] The process involves constructing a target pressure trajectory for each set of parameters in the secondary boost candidate parameter set that satisfies the pressure change rate constraint, forming a pressure target sequence, and calculating the corresponding smoothness index based on the pressure target sequence within the compensation evaluation time interval. Specifically, this includes:

[0167] For each triplet of secondary boost parameters in the candidate set of secondary boost parameters, the sampling point that is closest to the start time of secondary boost and is within the allowed index range is selected as the start sampling point of secondary boost based on the ratio of the start time of secondary boost to the sampling period in the triplet of secondary boost parameters.

[0168] Obtain the original liquid forging pressure value instant before the start of secondary pressurization, calculate the difference between the secondary pressurization platform pressure and the original liquid forging pressure value, and divide the absolute value of the pressure difference between the secondary pressurization platform pressure and the original liquid forging pressure value by the maximum pressure change rate allowed by the equipment to obtain the candidate pressure rise time required to transition from the original liquid forging pressure value to the secondary pressurization platform pressure under the upper limit constraint of the pressure change rate.

[0169] When the duration of the secondary boost is not less than the candidate pressure rise time, the candidate pressure rise time is taken as the actual pressure rise time. When the duration of the secondary boost is less than the candidate pressure rise time, the duration of the secondary boost is taken as the actual pressure rise time. The end time of the secondary boost rise segment is obtained by summing the start time of the secondary boost and the actual pressure rise time. The end time of the secondary boost platform holding segment is obtained by summing the start time of the secondary boost and the duration of the secondary boost.

[0170] When the actual pressure rise time is greater than zero, the original liquid forging pressure curve is maintained for all moments before the start of the secondary pressurization. From the start of the secondary pressurization to the end of the secondary pressurization rise segment, a linear interpolation is performed between the original liquid forging pressure value and the secondary pressurization platform pressure instantaneously before the start of the secondary pressurization. From the end of the secondary pressurization rise segment to the end of the secondary pressurization platform holding segment, the secondary pressurization platform pressure is maintained. After the end of the secondary pressurization platform holding segment, the original liquid forging pressure curve is restored. When the actual pressure rise time is equal to zero, the original liquid forging pressure curve is maintained before the start of the secondary pressurization. From the start of the secondary pressurization to the end of the secondary pressurization platform holding segment, the secondary pressurization platform pressure is maintained. After the end of the secondary pressurization platform holding segment, the original liquid forging pressure curve is restored. This yields the secondary pressurization target pressure trajectory over the entire time axis.

[0171] At all sampling times, the secondary pressurization target pressure trajectory corresponding to each sampling time is sampled to obtain the liquid forging pressure target sequence under the condition of applying secondary pressurization control.

[0172] Within the compensation assessment time interval, for each sampling interval, the secondary boosting pressure target value of each sampling interval is obtained by subtracting the original liquid forging pressure value and multiplying by the sampling period to obtain the additional pressure area increment of each sampling interval.

[0173] When the pressure area within the compensation assessment time interval is greater than zero without secondary pressurization, the total effective compensation displacement within the compensation assessment time interval is divided by the pressure area to obtain the effective compensation displacement per unit pressure area. The additional pressure area increment of each sampling interval is multiplied by the effective compensation displacement per unit pressure area to obtain the alternative effective compensation displacement converted from the additional pressure input for each sampling interval. This alternative effective compensation displacement increment is then added to the original effective compensation displacement increment of each sampling interval to obtain the alternative effective compensation displacement increment for each sampling interval. When the pressure area within the compensation assessment time interval is not greater than zero without secondary pressurization, the alternative effective compensation displacement increment for each sampling interval is recorded as the original effective compensation displacement increment for each sampling interval.

[0174] Within the compensation evaluation time interval, the parts of the alternative effective compensation displacement increments in all sampling intervals that are less than zero are treated as zero and then summed to obtain the total alternative effective compensation displacement corresponding to each secondary boosting parameter triplet.

[0175] Within the compensation assessment time interval, the product of the secondary boost pressure target value and the sampling period for all sampling intervals is added one by one to obtain the pressure input area corresponding to each secondary boost parameter triplet. When the pressure input area is greater than zero, the total effective compensation displacement is divided by the pressure input area to obtain the compensation channel smoothness index corresponding to each secondary boost parameter triplet. When the pressure input area is not greater than zero, the compensation smoothness index corresponding to each secondary boost parameter triplet is set to zero.

[0176] For a given candidate triple The index for calculating the start of secondary boost is:

[0177] ;in, This is the sampling index corresponding to the start of the second boost.

[0178] Calculate the candidate pressure rise time under the upper limit constraint of pressure change rate. Specifically: ;in, This refers to the initial pressure value just before the second pressurization begins; For sampling index The original pressure value at the location; This is the upper limit of the allowable pressure change rate for the equipment;

[0179] Construct the secondary boost rise time of actual sampling Specifically:

[0180] ;

[0181] Set the end time of the secondary boost phase as... ;

[0182] Set the end time of the secondary booster platform holding section as... ;

[0183] like The secondary boost pressure trajectory is then constructed as follows:

[0184] ;in, The target pressure trajectory under secondary pressurization control; The original pressure over time without the application of secondary pressurization control;

[0185] like Then let the secondary boost pressure trajectory be:

[0186] ;

[0187] for The secondary boost pressure sequence is constructed as follows: ;in, In the first Each sampling time The corresponding target secondary boost pressure value;

[0188] for The additional pressure area increment is calculated as follows:

[0189] ;in, In the first The additional pressure area increase caused by secondary pressurization within each sampling interval;

[0190] like For The alternative to the single-step effective displacement increment is constructed as follows: ;in, After taking into account the impact of additional pressure input, the first The effective compensation displacement increment for each sampling interval;

[0191] like Then let: ;

[0192] The effective replacement compensation displacement is calculated as follows:

[0193] ;in, To achieve a given secondary boosting parameter Below, the total effective compensation displacement within the compensation assessment interval;

[0194] The calculation of the secondary booster pressure input is as follows:

[0195] ;in, To calculate the target pressure area within the evaluation interval under given secondary boosting parameters;

[0196] like Then the secondary boosting smoothness is:

[0197] ;in, This refers to the smoothness index of the compensation channel under given secondary boosting parameters;

[0198] like Then let: .

[0199] The process of selecting the parameter group with the highest smoothness index from the candidate parameter set for secondary boosting, obtaining the optimal secondary boosting start time, optimal secondary boosting platform pressure, and optimal secondary boosting duration, and forming the optimal secondary boosting parameters, and performing pressure change rate constraint correction and boundary correction on the optimal secondary boosting parameters, specifically includes:

[0200] In the set of secondary boosting candidate parameters, the secondary boosting pressure curve and alternative smoothness calculation steps are called for each secondary boosting parameter triplet to obtain the corresponding compensation channel smoothness index, and the smoothness value with the largest smoothness index is selected as the maximum smoothness value among all candidates.

[0201] In the set of candidate secondary boost parameters, all triplet parameters of secondary boost parameters whose compensation channel smoothness index is equal to the maximum smoothness value are selected to form the maximum smoothness parameter set.

[0202] In the maximum smoothness parameter set, the parameter triplet with the smallest secondary boost start time is selected first. When there are multiple parameter triplets with the same secondary boost start time, the parameter triplet with the smaller secondary boost platform pressure is selected from these parameter triplets. When there are still multiple parameter triplets, the parameter triplet with the smaller secondary boost duration is selected from these parameter triplets to obtain the optimal secondary boost start time, optimal secondary boost platform pressure, and optimal secondary boost duration.

[0203] By substituting the optimal secondary boost parameters into the secondary boost pressure curve and the secondary boost target pressure trajectory construction process in the alternative smoothness calculation, the optimal secondary boost pressure target sequence over the entire sampling time axis is obtained.

[0204] In the optimal secondary boost pressure target sequence, for each sampling interval except the initial sampling point, the optimal secondary boost pressure target value of the next sampling point in each sampling interval is calculated by subtracting the optimal secondary boost pressure target value of the previous sampling point from the optimal secondary boost pressure target value of the next sampling point. The difference between the optimal secondary boost pressure target value of the next sampling point and the optimal secondary boost pressure target value of the previous sampling point is divided by the sampling period to obtain the discrete pressure change rate of each sampling interval. The maximum discrete pressure change rate is selected from all sampling intervals as the maximum discrete pressure change rate in the optimal secondary boost pressure target sequence.

[0205] When the maximum discrete pressure change rate on the optimal secondary boosting pressure target sequence is not greater than the maximum pressure change rate allowed by the equipment, the optimal secondary boosting platform pressure is kept constant and used as the corrected optimal secondary boosting platform pressure. When the maximum discrete pressure change rate on the optimal secondary boosting pressure target sequence is greater than the maximum pressure change rate allowed by the equipment, the original liquid forging pressure value is obtained instantaneously before the start of the optimal secondary boosting. The product of the maximum pressure change rate allowed by the equipment and the duration of the optimal secondary boosting is used as the maximum allowable pressure increment. When the optimal secondary boosting platform pressure is higher than the original liquid forging pressure value, the maximum allowable pressure increment is added to the original liquid forging pressure value to obtain the corrected optimal secondary boosting platform pressure. When the optimal secondary boosting platform pressure is lower than the original liquid forging pressure value, the maximum allowable pressure increment is subtracted from the original liquid forging pressure value to obtain the corrected optimal secondary boosting platform pressure. When the optimal secondary boosting platform pressure is equal to the original liquid forging pressure value, the original liquid forging pressure value is used as the corrected optimal secondary boosting platform pressure.

[0206] The optimal secondary boost start time is used as the corrected optimal secondary boost start time. When the corrected optimal secondary boost start time is less than the lower limit of the secondary boost start time, the corrected optimal secondary boost start time is set as the lower limit of the secondary boost start time. When the corrected optimal secondary boost start time is greater than the upper limit of the secondary boost start time, the corrected optimal secondary boost start time is set as the upper limit of the secondary boost start time.

[0207] When the corrected optimal secondary booster platform pressure is less than the lower limit of the secondary booster platform pressure allowed by the process, the corrected optimal secondary booster platform pressure is set to the lower limit of the secondary booster platform pressure allowed by the process. When the corrected optimal secondary booster platform pressure is greater than the upper limit of the secondary booster platform pressure allowed by the process, the corrected optimal secondary booster platform pressure is set to the upper limit of the secondary booster platform pressure allowed by the process.

[0208] The optimal secondary boost duration is used as the corrected optimal secondary boost duration. When the corrected optimal secondary boost duration is less than the lower limit of the secondary boost duration, the corrected optimal secondary boost duration is set as the lower limit of the secondary boost duration. When the corrected optimal secondary boost duration is greater than the upper limit of the secondary boost duration, the corrected optimal secondary boost duration is set as the upper limit of the secondary boost duration.

[0209] In the candidate set The corresponding smoothness is calculated above. ;

[0210] To find the maximum smoothness, we need to: ;in, In the candidate set The maximum achievable smoothness value;

[0211] Build smoothness to the maximum Set of all candidate secondary boost parameters triplet Specifically:

[0212] ;

[0213] From the set Select the optimal triplet Specifically:

[0214] S701, Select from all candidates the smallest;

[0215] S702, If multiple candidates have the same Choose from the smallest;

[0216] S703. If there are still multiple candidates, then select from them. the smallest;

[0217] in, This is the final selected optimal start time for secondary boosting; The optimal pressure for the secondary booster platform; The optimal duration for secondary boosting;

[0218] Using the optimal triplet Substitute the secondary boost pressure trajectory Calculate the secondary boost pressure sequence ;

[0219] The maximum rate of change of pressure is calculated as follows:

[0220] ;in, To achieve the target pressure sequence of secondary boosting The maximum discrete pressure change rate calculated above;

[0221] like Then keep constant;

[0222] like The corrected pressure platform calculated based on the optimal triplet is as follows: ;in, This is a sign function that returns 1 when the value inside the parentheses is greater than 0, 0 when the value inside the parentheses is equal to 0, and -1 when the value inside the parentheses is less than 0. The optimal time to start secondary boost The initial pressure value at the moment before; To match the optimal start time The corresponding secondary boost begins sampling index;

[0223] The boundary projection is performed at the optimal starting time, specifically as follows:

[0224] ;

[0225] The optimal pressure platform is projected onto its boundary as follows:

[0226] ;

[0227] The boundary projection of the optimal duration is as follows:

[0228] .

[0229] The process of generating a pressure setting command sequence based on the corrected optimal secondary boosting parameters and sending it to the hydraulic system for execution, while simultaneously storing the pressure setting command sequence, specifically includes:

[0230] The corrected optimal secondary boost start time, the corrected optimal secondary boost platform pressure, and the corrected optimal secondary boost duration are combined to form the optimal secondary boost parameter set;

[0231] Substituting the optimal set of secondary boosting parameters into the secondary boosting pressure curve and the secondary boosting target pressure trajectory construction process in the alternative smoothness calculation, the optimal secondary boosting target pressure trajectory covering the entire liquid forging process is generated under the condition of satisfying the pressure change rate constraint.

[0232] At all sampling times, the optimal secondary pressurization target pressure trajectory is sampled, and the pressure setpoint corresponding to each sampling time is obtained. The pressure setpoint is then arranged in the order of the sampling times to form a pressure setpoint instruction sequence.

[0233] Based on the optimal set of secondary boost parameters, the actual pressure rise time under the optimal set of secondary boost parameters is calculated according to the actual pressure rise time calculation method in the secondary boost pressure curve and the substitution smoothness calculation. The sum of the corrected optimal secondary boost start time and the actual pressure rise time is divided by the sampling period to obtain the sampling index corresponding to the end time of the secondary boost rise segment. When the calculated sampling index is greater than the last sampling index, the calculated sampling index is set as the last sampling index.

[0234] Based on the optimal secondary boost parameter set, calculate the sum of the corrected optimal secondary boost start time and the corrected optimal secondary boost duration, divide by the sampling period, and obtain the sampling index corresponding to the end time of the secondary boost platform holding segment. When the calculated sampling index is greater than the last sampling index, set the calculated sampling index as the last sampling index.

[0235] The pressure setting command sequence is sent to the hydraulic system in the sampling order to perform secondary pressure boosting control, and the pressure setting command sequence is stored and solidified.

[0236] The final optimal quadratic boost decision vector is constructed as follows: ;

[0237] use Substitute the secondary boost pressure trajectory The corresponding pressure trajectory is calculated in the segmented definition;

[0238] for The generated pressure setting sequence is as follows: ;in, In the first Each sampling time The pressure setting command value should be sent to the hydraulic system.

[0239] Calculate the sampling index corresponding to the end time of the optimal secondary boost ramp-up phase. Specifically:

[0240] ;in, The rise time is calculated under the optimal secondary boost parameters;

[0241] Calculate the sampling index corresponding to the end time of the optimal secondary boost holding period. Specifically:

[0242] .

[0243] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0244] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An optimized control method for a wheel hub liquid forging process, characterized in that, include: Set up a punch displacement sensor and a liquid forging pressure sensor, synchronously collect displacement voltage signals and pressure voltage signals according to the sampling period, complete calibration and zero point correction, and generate punch displacement sampling sequence and liquid forging pressure sampling sequence; The displacement change rate sequence and pressure change rate sequence are calculated based on the punch displacement sampling sequence and the liquid forging pressure sampling sequence, and an effective compensation displacement increment sequence is constructed according to the displacement increment. Based on the statistical thresholds of the displacement change rate sequence and the pressure change rate sequence, the filling end sampling interval and the shrinkage assessment termination sampling interval are obtained, forming the shrinkage assessment time interval; The total effective shrinkage displacement is obtained by accumulating the effective shrinkage displacement increment within the shrinkage assessment time interval. The pressure area is obtained by integrating the liquid forging pressure over time. A smoothness index is constructed based on the total effective shrinkage displacement and the pressure area. Set the start time of secondary boost, the pressure of the secondary boost platform, and the duration of secondary boost as decision variables for secondary boost, and generate a set of candidate parameters for secondary boost discretization within the allowable range; For each set of parameters in the secondary boost candidate parameter set, construct a secondary boost target pressure trajectory that satisfies the pressure change rate constraint, form a pressure target sequence, and calculate the corresponding smoothness index based on the pressure target sequence within the compensation evaluation time interval; Select the parameter group with the highest smoothness index from the set of secondary boosting candidate parameters, obtain the optimal secondary boosting start time, optimal secondary boosting platform pressure, and optimal secondary boosting duration, and form the optimal secondary boosting parameters. Perform pressure change rate constraint correction and boundary correction on the optimal secondary boosting parameters. The pressure setting command sequence is generated based on the corrected optimal secondary boosting parameters and sent to the hydraulic system for execution. At the same time, the pressure setting command sequence is stored.

2. The optimized control method for a wheel hub liquid forging process according to claim 1, characterized in that, The process involves setting up a punch displacement sensor and a liquid forging pressure sensor to synchronously acquire displacement voltage signals and pressure voltage signals according to a sampling period, completing calibration and zero-point correction, and generating punch displacement sampling sequences and liquid forging pressure sampling sequences. Specifically, this includes: A displacement sensor is set in the direction of the punch movement in the liquid forging equipment to collect the original voltage signal corresponding to the punch displacement. The voltage discrete sequence of the displacement sensor is formed by sequentially collecting the data at a fixed sampling period through a data acquisition device, and each sampling point is assigned an index number that increases in time sequence. A pressure sensor is set in the liquid forging pressure channel to collect the original voltage signal corresponding to the liquid forging pressure. The voltage discrete sequence of the pressure sensor is synchronously collected by the data acquisition device at the same sampling period as the displacement sampling, and each sampling point is assigned a consistent index number corresponding to the displacement sampling. Select the first and second sets of standard displacement values ​​for displacement calibration, obtain the voltage readings output by the displacement sensor under the two sets of standard displacement values, obtain the proportional coefficient of displacement to voltage by the ratio of the difference between the two sets of standard displacement values ​​to the difference between the two sets of voltage readings, and obtain the displacement calibration intercept by subtracting the product of the proportional coefficient and the first set of voltage readings from the first set of standard displacement values. For each sampling point of the displacement sensor, the voltage reading of each sampling point is multiplied by the displacement-voltage ratio coefficient, and the displacement calibration intercept is added to obtain the punch displacement value corresponding to each sampling point, forming a discrete sequence of punch displacement. Select the first and second sets of standard pressure values ​​for pressure calibration, obtain the voltage readings output by the pressure sensor under the two sets of standard pressure values, obtain the pressure-voltage proportionality coefficient by the ratio of the difference between the two sets of standard pressure values ​​to the difference between the two sets of voltage readings, and obtain the pressure calibration intercept by subtracting the product of the proportionality coefficient and the first set of voltage readings from the first set of standard pressure values. For each sampling point of the pressure sensor, the voltage reading of each sampling point is multiplied by the pressure-voltage ratio coefficient, and then the pressure calibration intercept is added to obtain the liquid forging pressure value corresponding to each sampling point, forming a discrete sequence of liquid forging pressure. Before the injection begins, a synchronous sampling is performed to obtain the punch displacement value and liquid forging pressure value at the initial sampling point; For all sampling points, subtract the initial sampling point's punch displacement value from the punch displacement value of each sampling point and update it with the corrected punch displacement value. At the same time, subtract the initial sampling point's liquid forging pressure value from the liquid forging pressure value of each sampling point and update it with the corrected liquid forging pressure value.

3. The optimized control method for a wheel hub liquid forging process according to claim 2, characterized in that, The calculation of the displacement change rate sequence and pressure change rate sequence based on the punch displacement sampling sequence and the liquid forging pressure sampling sequence, and the construction of an effective compensation displacement increment sequence according to the displacement increment, specifically includes: Based on the discrete sequence of punch displacement obtained at a fixed sampling period, for each sampling interval except the initial sampling point, the punch displacement value of the next sampling point in each sampling interval is obtained by subtracting the punch displacement value of the previous sampling point, and the difference between the punch displacement value of the next sampling point and the punch displacement value of the previous sampling point is divided by the sampling period to obtain the average displacement change rate in each sampling interval, thus forming a displacement change rate sequence. Based on the discrete sequence of liquid forging pressure obtained at a fixed sampling period, for each sampling interval except the initial sampling point, the liquid forging pressure value of the next sampling point in each sampling interval is obtained by subtracting the liquid forging pressure value of the previous sampling point, and the difference between the liquid forging pressure value of the next sampling point and the liquid forging pressure value of the previous sampling point is divided by the sampling period to obtain the average pressure change rate in each sampling interval, thus forming a pressure change rate sequence. For each sampling interval, when the punch displacement value of the next sampling point in each sampling interval is greater than the punch displacement value of the previous sampling point, the difference between the punch displacement value of the next sampling point and the punch displacement value of the previous sampling point is taken as the effective compensation displacement increment of the current sampling interval. When the punch displacement value of the next sampling point in each sampling interval is not greater than the punch displacement value of the previous sampling point, the effective compensation displacement increment of the current sampling interval is recorded as zero, forming an effective compensation displacement increment sequence.

4. The optimized control method for a wheel hub liquid forging process according to claim 3, characterized in that, The method of obtaining the filling end sampling interval and the shrinkage evaluation termination sampling interval based on the statistical thresholds of the displacement change rate sequence and the pressure change rate sequence, forming the shrinkage evaluation time interval, specifically includes: The displacement change velocity sequences of all sampling intervals are statistically analyzed, and the displacement change velocity sequences are sorted from smallest to largest. The value at which the cumulative probability is 95% is used as the 95th percentile threshold of the displacement change velocity. In all sampling intervals except the last one, select a set of sampling interval indices that satisfy the condition that the displacement change rate of the current sampling interval is not greater than the 95th percentile threshold of the displacement change rate and the displacement change rate of the next sampling interval is not greater than the 95th percentile threshold of the displacement change rate. When the index set is not empty, select the sampling interval with the smallest index from the index set as the filling end sampling interval. When the index set is empty, select the second to last sampling interval as the filling end sampling interval. The continuous time corresponding to the end of filling is obtained by multiplying the index of the sampling interval at the end of filling with the sampling period. The absolute values ​​of the pressure change rate sequence in all sampling intervals are statistically analyzed. The absolute values ​​of the pressure change rate sequence are sorted from smallest to largest. The value at the point with a cumulative probability of 5% is used as the 5% quantile threshold of the absolute value of the pressure change rate. After the filling end sampling interval and in all sampling intervals except the last sampling interval, select the sampling interval index set that satisfies the condition that the absolute value of the pressure change rate of this sampling interval is not greater than the 5th percentile threshold of the absolute value of the pressure change rate and the absolute value of the pressure change rate of the subsequent sampling interval is not greater than the 5th percentile threshold of the absolute value of the pressure change rate. When the index set is not empty, select the sampling interval with the smallest index from the index set as the termination sampling interval for the compensation evaluation. When the index set is empty, use the last sampling interval as the termination sampling interval for the compensation evaluation. Based on the product of the index of the termination sampling interval of the compensation assessment and the sampling period, the continuous time corresponding to the termination time of the compensation assessment is obtained, and the time interval between the end sampling interval of the filling end and the termination sampling interval of the compensation assessment is taken as the compensation assessment time interval.

5. The optimized control method for a wheel hub liquid forging process according to claim 4, characterized in that, The process involves accumulating the effective shrinkage displacement increments within the shrinkage assessment time interval to obtain the total effective shrinkage displacement, integrating the liquid forging pressure over time to obtain the pressure area, and constructing a smoothness index based on the total effective shrinkage displacement and the pressure area. Specifically, this includes: Within the time interval of the compensation assessment, the effective compensation displacement increments of each sampling interval are added one by one to obtain the total effective compensation displacement within the time interval of the compensation assessment. Within the shrinkage assessment time interval, the product of the liquid forging pressure value and the sampling period for each sampling interval is added one by one to obtain the pressure area within the shrinkage assessment time interval, which is the integral result of the liquid forging pressure over time within the shrinkage assessment time interval. When the pressure area during the compensation assessment time interval is greater than zero, the total effective compensation displacement is divided by the pressure area to obtain the baseline smoothness index of the wheel hub compensation channel without secondary pressurization. When the pressure area is not greater than zero, the baseline smoothness index is set to zero.

6. The optimized control method for a wheel hub liquid forging process according to claim 5, characterized in that, The process of setting the start time of secondary boosting, the pressure of the secondary boosting platform, and the duration of secondary boosting as decision variables for secondary boosting, and discretizing and generating a set of candidate parameters for secondary boosting within an allowable range, specifically includes: The secondary boosting start time, secondary boosting platform pressure, and secondary boosting duration are set as secondary boosting decision variables. The lower limit and upper limit of the secondary boosting start time are set for the secondary boosting start time, the lower limit and upper limit of the secondary boosting platform pressure are set for the secondary boosting platform pressure, and the lower limit and upper limit of the secondary boosting duration are set for the secondary boosting duration. Based on the end time of filling, the start time of secondary boosting is discretized after the end time of filling by an integer multiple of the sampling period to obtain a set of possible candidate values ​​for the start time of secondary boosting, which are limited to the lower limit and the upper limit of the start time of secondary boosting. Using the sampling period as the unit, the duration of secondary boost is expressed as a positive integer multiple of the sampling period, resulting in a set of possible candidate values ​​for the duration of secondary boost, which are limited to the lower limit and the upper limit of the duration of secondary boost. Using a preset pressure setting resolution as the step size, starting from the lower limit of the secondary pressurization platform pressure allowed by the process, gradually increase to obtain a set of candidate pressure values ​​for the secondary pressurization platform, and limit them between the lower limit and the upper limit of the secondary pressurization platform pressure allowed by the process. By combining candidate values ​​for the start time of secondary boosting, candidate values ​​for the pressure of the secondary boosting platform, and candidate values ​​for the duration of secondary boosting, a triplet of secondary boosting parameters that simultaneously satisfies the constraints of the range of values ​​for the start time of secondary boosting, the range of values ​​for the pressure of the secondary boosting platform, and the range of values ​​for the duration of secondary boosting is selected, thus forming a set of candidate secondary boosting parameters. When the set of secondary boosting candidate parameters is empty, the lower limit of the secondary boosting start time and the upper limit of the secondary boosting start time are added together and divided by two to obtain the intermediate value as the secondary boosting start time. The lower limit of the secondary boosting platform pressure allowed by the process and the upper limit of the secondary boosting platform pressure allowed by the process are added together and divided by two to obtain the intermediate value as the secondary boosting platform pressure. The lower limit of the secondary boosting duration and the upper limit of the secondary boosting duration are added together and divided by two to obtain the intermediate value as the secondary boosting duration. The secondary boosting parameter triple consisting of the three sets of intermediate values ​​is added to the secondary boosting candidate parameter set as the unique element.

7. The optimized control method for a wheel hub liquid forging process according to claim 6, characterized in that, The process involves constructing a target pressure trajectory for each set of parameters in the secondary boost candidate parameter set that satisfies the pressure change rate constraint, forming a pressure target sequence, and calculating the corresponding smoothness index based on the pressure target sequence within the compensation evaluation time interval. Specifically, this includes: For each triplet of secondary boost parameters in the candidate set of secondary boost parameters, the sampling point that is closest to the start time of secondary boost and is within the allowed index range is selected as the start sampling point of secondary boost based on the ratio of the start time of secondary boost to the sampling period in the triplet of secondary boost parameters. Obtain the original liquid forging pressure value instant before the start of secondary pressurization, calculate the difference between the secondary pressurization platform pressure and the original liquid forging pressure value, and divide the absolute value of the pressure difference between the secondary pressurization platform pressure and the original liquid forging pressure value by the maximum pressure change rate allowed by the equipment to obtain the candidate pressure rise time required to transition from the original liquid forging pressure value to the secondary pressurization platform pressure under the upper limit constraint of the pressure change rate. When the duration of the secondary boost is not less than the candidate pressure rise time, the candidate pressure rise time is taken as the actual pressure rise time. When the duration of the secondary boost is less than the candidate pressure rise time, the duration of the secondary boost is taken as the actual pressure rise time. The end time of the secondary boost rise segment is obtained by summing the start time of the secondary boost and the actual pressure rise time. The end time of the secondary boost platform holding segment is obtained by summing the start time of the secondary boost and the duration of the secondary boost. When the actual pressure rise time is greater than zero, the original liquid forging pressure curve is maintained for all moments before the start of the secondary pressurization. From the start of the secondary pressurization to the end of the secondary pressurization rise segment, a linear interpolation is performed between the original liquid forging pressure value and the secondary pressurization platform pressure instantaneously before the start of the secondary pressurization. From the end of the secondary pressurization rise segment to the end of the secondary pressurization platform holding segment, the secondary pressurization platform pressure is maintained. After the end of the secondary pressurization platform holding segment, the original liquid forging pressure curve is restored. When the actual pressure rise time is equal to zero, the original liquid forging pressure curve is maintained before the start of the secondary pressurization. From the start of the secondary pressurization to the end of the secondary pressurization platform holding segment, the secondary pressurization platform pressure is maintained. After the end of the secondary pressurization platform holding segment, the original liquid forging pressure curve is restored. This yields the secondary pressurization target pressure trajectory over the entire time axis. At all sampling times, the secondary pressurization target pressure trajectory corresponding to each sampling time is sampled to obtain the liquid forging pressure target sequence under the condition of applying secondary pressurization control. Within the compensation assessment time interval, for each sampling interval, the secondary boosting pressure target value of each sampling interval is obtained by subtracting the original liquid forging pressure value and multiplying by the sampling period to obtain the additional pressure area increment of each sampling interval. When the pressure area within the compensation assessment time interval is greater than zero without secondary pressurization, the total effective compensation displacement within the compensation assessment time interval is divided by the pressure area to obtain the effective compensation displacement per unit pressure area. The additional pressure area increment of each sampling interval is multiplied by the effective compensation displacement per unit pressure area to obtain the alternative effective compensation displacement converted from the additional pressure input for each sampling interval. This alternative effective compensation displacement increment is then added to the original effective compensation displacement increment of each sampling interval to obtain the alternative effective compensation displacement increment for each sampling interval. When the pressure area within the compensation assessment time interval is not greater than zero without secondary pressurization, the alternative effective compensation displacement increment for each sampling interval is recorded as the original effective compensation displacement increment for each sampling interval. Within the compensation evaluation time interval, the parts of the alternative effective compensation displacement increments in all sampling intervals that are less than zero are treated as zero and then summed to obtain the total alternative effective compensation displacement corresponding to each secondary boosting parameter triplet. Within the compensation assessment time interval, the product of the secondary boost pressure target value and the sampling period for all sampling intervals is added one by one to obtain the pressure input area corresponding to each secondary boost parameter triplet. When the pressure input area is greater than zero, the total effective compensation displacement is divided by the pressure input area to obtain the compensation channel smoothness index corresponding to each secondary boost parameter triplet. When the pressure input area is not greater than zero, the compensation smoothness index corresponding to each secondary boost parameter triplet is set to zero.

8. The optimized control method for a wheel hub liquid forging process according to claim 7, characterized in that, The process of selecting the parameter group with the highest smoothness index from the candidate parameter set for secondary boosting, obtaining the optimal secondary boosting start time, optimal secondary boosting platform pressure, and optimal secondary boosting duration, and forming the optimal secondary boosting parameters, and performing pressure change rate constraint correction and boundary correction on the optimal secondary boosting parameters, specifically includes: In the set of secondary boosting candidate parameters, the secondary boosting pressure curve and alternative smoothness calculation steps are called for each secondary boosting parameter triplet to obtain the corresponding compensation channel smoothness index, and the smoothness value with the largest smoothness index is selected as the maximum smoothness value among all candidates. In the set of candidate secondary boost parameters, all triplet parameters of secondary boost parameters whose compensation channel smoothness index is equal to the maximum smoothness value are selected to form the maximum smoothness parameter set. In the maximum smoothness parameter set, the parameter triplet with the smallest secondary boost start time is selected first. When there are multiple parameter triplets with the same secondary boost start time, the parameter triplet with the smaller secondary boost platform pressure is selected from these parameter triplets. When there are still multiple parameter triplets, the parameter triplet with the smaller secondary boost duration is selected from these parameter triplets to obtain the optimal secondary boost start time, optimal secondary boost platform pressure, and optimal secondary boost duration. By substituting the optimal secondary boost parameters into the secondary boost pressure curve and the secondary boost target pressure trajectory construction process in the alternative smoothness calculation, the optimal secondary boost pressure target sequence over the entire sampling time axis is obtained. In the optimal secondary boost pressure target sequence, for each sampling interval except the initial sampling point, the optimal secondary boost pressure target value of the next sampling point in each sampling interval is calculated by subtracting the optimal secondary boost pressure target value of the previous sampling point from the optimal secondary boost pressure target value of the next sampling point. The difference between the optimal secondary boost pressure target value of the next sampling point and the optimal secondary boost pressure target value of the previous sampling point is divided by the sampling period to obtain the discrete pressure change rate of each sampling interval. The maximum discrete pressure change rate is selected from all sampling intervals as the maximum discrete pressure change rate in the optimal secondary boost pressure target sequence. When the maximum discrete pressure change rate on the optimal secondary boosting pressure target sequence is not greater than the maximum pressure change rate allowed by the equipment, the optimal secondary boosting platform pressure is kept constant and used as the corrected optimal secondary boosting platform pressure. When the maximum discrete pressure change rate on the optimal secondary boosting pressure target sequence is greater than the maximum pressure change rate allowed by the equipment, the original liquid forging pressure value is obtained instantaneously before the start of the optimal secondary boosting. The product of the maximum pressure change rate allowed by the equipment and the duration of the optimal secondary boosting is used as the maximum allowable pressure increment. When the optimal secondary boosting platform pressure is higher than the original liquid forging pressure value, the maximum allowable pressure increment is added to the original liquid forging pressure value to obtain the corrected optimal secondary boosting platform pressure. When the optimal secondary boosting platform pressure is lower than the original liquid forging pressure value, the maximum allowable pressure increment is subtracted from the original liquid forging pressure value to obtain the corrected optimal secondary boosting platform pressure. When the optimal secondary boosting platform pressure is equal to the original liquid forging pressure value, the original liquid forging pressure value is used as the corrected optimal secondary boosting platform pressure. The optimal secondary boost start time is used as the corrected optimal secondary boost start time. When the corrected optimal secondary boost start time is less than the lower limit of the secondary boost start time, the corrected optimal secondary boost start time is set as the lower limit of the secondary boost start time. When the corrected optimal secondary boost start time is greater than the upper limit of the secondary boost start time, the corrected optimal secondary boost start time is set as the upper limit of the secondary boost start time. When the corrected optimal secondary booster platform pressure is less than the lower limit of the secondary booster platform pressure allowed by the process, the corrected optimal secondary booster platform pressure is set to the lower limit of the secondary booster platform pressure allowed by the process. When the corrected optimal secondary booster platform pressure is greater than the upper limit of the secondary booster platform pressure allowed by the process, the corrected optimal secondary booster platform pressure is set to the upper limit of the secondary booster platform pressure allowed by the process. The optimal secondary boost duration is used as the corrected optimal secondary boost duration. When the corrected optimal secondary boost duration is less than the lower limit of the secondary boost duration, the corrected optimal secondary boost duration is set as the lower limit of the secondary boost duration. When the corrected optimal secondary boost duration is greater than the upper limit of the secondary boost duration, the corrected optimal secondary boost duration is set as the upper limit of the secondary boost duration.

9. The optimized control method for a wheel hub liquid forging process according to claim 8, characterized in that, The process of generating a pressure setting command sequence based on the corrected optimal secondary boosting parameters and sending it to the hydraulic system for execution, while simultaneously storing the pressure setting command sequence, specifically includes: The corrected optimal secondary boost start time, the corrected optimal secondary boost platform pressure, and the corrected optimal secondary boost duration are combined to form the optimal secondary boost parameter set; Substituting the optimal set of secondary boosting parameters into the secondary boosting pressure curve and the secondary boosting target pressure trajectory construction process in the alternative smoothness calculation, the optimal secondary boosting target pressure trajectory covering the entire liquid forging process is generated under the condition of satisfying the pressure change rate constraint. At all sampling times, the optimal secondary pressurization target pressure trajectory is sampled, and the pressure set value corresponding to each sampling time is obtained. The pressure set command sequence is formed by arranging the sampling times in order. Based on the optimal set of secondary boost parameters, the actual pressure rise time under the optimal set of secondary boost parameters is calculated according to the actual pressure rise time calculation method in the secondary boost pressure curve and the substitution smoothness calculation. The sum of the corrected optimal secondary boost start time and the actual pressure rise time is divided by the sampling period to obtain the sampling index corresponding to the end time of the secondary boost rise segment. When the calculated sampling index is greater than the last sampling index, the calculated sampling index is set as the last sampling index. Based on the optimal secondary boost parameter set, calculate the sum of the corrected optimal secondary boost start time and the corrected optimal secondary boost duration, divide by the sampling period, and obtain the sampling index corresponding to the end time of the secondary boost platform holding segment. When the calculated sampling index is greater than the last sampling index, set the calculated sampling index as the last sampling index. The pressure setting command sequence is sent to the hydraulic system in the sampling order to perform secondary pressure boosting control, and the pressure setting command sequence is stored and solidified.

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