Adaptive control method for the press mechanism of a press

Abstract

This invention relates to the field of general press technology and discloses an adaptive control method for the pressure mechanism of a press. The method includes: collecting pressure and displacement parameters generated by the material being pressed during the downward stroke of the slide block; calculating the slope of the pressure evolution relative to the displacement to obtain a real-time resistance gradient; determining parameter coordinate points in a reference coordinate system based on the real-time resistance gradient; projecting these points onto a topological reference surface generated by the mold boundary and rheological limit calibration; calculating the normal deviation distance of the parameter coordinate points relative to the topological reference surface to determine the pressure overshoot margin; and triggering a pressure cutoff signal and driving the hydraulic circuit to release pressure when the overshoot margin reaches an action threshold. This invention converts physical overshoot into geometric deviation, achieving real-time feedback adjustment of the downward pressure of the slide block, effectively compensating for the inertial overshoot of the main drive chain, and solving the problem of pressure holding instability in the molding of high-strength materials.

Description

Technical Field

[0001] This invention belongs to the field of general press technology, and particularly relates to an adaptive control method for the pressure mechanism of a press. Background Technology

[0002] In the current metal forming process, presses apply pressure to the blank in the mold by driving a slider, causing it to undergo plastic deformation. With the widespread application of high-strength steel, titanium alloys, and composite materials in manufacturing, the forming process has placed higher demands on load accuracy and pressure holding stability. Existing closed-loop control mechanisms mainly rely on pressure sensors to monitor the real-time load and stop energy output when the actual pressure reaches a preset target threshold. However, the press's drive mechanism has physical inertia that cannot be completely eliminated. This inertia originates from the compressive potential energy of the hydraulic fluid or the rotational kinetic energy of the mechanical transmission system. When the slider contacts the material and builds up pressure, there is an inherent physical time delay between the controller capturing the signal and the actuator completely stopping its action. Since high-strength metals have obvious nonlinear rheological characteristics during the plastic deformation stage, the sudden change in the yield point prevents the redundant energy accumulated in the drive system from being unloaded instantly, inevitably resulting in pressure overshoot. This phenomenon not only causes local thinning of the formed part but also applies periodic alternating impacts to the mold and the equipment frame.

[0003] Existing industry attempts to improve the pressing process primarily involve increasing frame rigidity or reducing pressing speed. Analysis reveals that these solutions fail to eliminate the phase misalignment between physical inertia and material resistance evolution at the source of load application timing, resulting in poor adaptability of pressing accuracy to material thickness tolerances and environmental temperature fluctuations. Besides the physical constraints of the mechanical structure, the control-level algorithm also faces challenges. For example, Chinese invention patent application CN114244230A... A method for suppressing pressure overshoot in a hydraulic system for a permanent magnet synchronous motor used in die casting machines is disclosed. By setting a pressure suppression threshold, the motor speed is linearly proportionally limited. Under complex metal stamping, the rheological resistance of the material fluctuates dynamically and nonlinearly with the amount of reduction. One-dimensional pressure feedback logic cannot capture the sudden change in the slope of the material entering the yield stage in real time. It lacks a mapping relationship between the geometric topological boundary of the mold and the physical forming limit. When faced with hysteresis drift caused by blank thickness tolerance or environmental temperature rise, it is difficult to accurately quantify the energy cutoff geometric allowance, resulting in compensation lag or overshoot. It cannot meet the requirements of real-time adaptive load control for high-precision forming.

[0004] Therefore, how to couple slider displacement with driving load to identify real-time resistance gradient, and combine system physical time delay to achieve adaptive truncation of load application process, has become the technical problem to be solved by this invention. Summary of the Invention

[0005] This invention provides an adaptive control method for the pressure mechanism of a press, comprising the following steps: Step S1: Collect the pressure parameters and displacement parameters generated when the slider presses the material during the downward forming stroke, and calculate the slope of the change of the pressure parameters relative to the displacement parameters to obtain real-time resistance gradient data that characterizes the evolution law of physical resistance. Step S2: Determine the real-time parameter coordinate points in the reference coordinate system based on the real-time resistance gradient data, and project the real-time parameter coordinate points onto a preset topological reference surface. The topological reference surface is generated by the topological boundary of the press mold and the rheological limit calibration of the material. Step S3: Obtain the normal deviation distance of the real-time parameter coordinate point relative to the topological reference surface, and determine the overshoot allowance of the current pressure state relative to the physical forming limit based on the normal deviation distance. Step S4: Determine whether the overshoot margin has reached the preset action threshold, and trigger the pressure cut-off signal when the overshoot margin reaches the action threshold to drive the pressure regulating unit of the press to complete the hydraulic circuit depressurization; the method uses a reference coordinate system to map the physical overshoot to geometric position deviation, and realizes dynamic adjustment of the downward pressure of the slider based on the feedback logic of the normal deviation distance.

[0006] Preferably, the process of determining the real-time parameter coordinate points in step S2 includes: The instantaneous displacement data of the slider and the pressure data of the master cylinder are acquired synchronously through a feedback link that couples the displacement sensor and the pressure sensor. Calculate the first derivative of the master cylinder pressure data with respect to the instantaneous displacement data, and determine it as the real-time resistance gradient data; Real-time resistance gradient data, instantaneous displacement data, and main cylinder pressure data are used as three-dimensional components to generate real-time parameter coordinate points that characterize the real-time physical state of the press.

[0007] Preferably, the logic for calculating the normal deviation distance in step S3 includes: Search for the surface boundary point on the topological reference surface that is geometrically closest to the real-time parameter coordinate point, and determine the surface boundary point as the reference point; Determine the difference vector between the real-time parameter coordinate points and the reference point; Perform vector magnitude operation on the difference vector and determine the result as the normal deviation distance.

[0008] Preferably, after step S4, a fluid transmission parameter correction step is also included: During the return phase of the stamping cycle, the deviation between the actual peak pressure of the stamping cycle and the preset target pressure is obtained. The fluid transmission hysteresis constant of the press is corrected by step superposition based on the deviation value; The modified fluid transmission hysteresis constant is used to adjust the action threshold of the next stamping cycle to compensate for the pressure transmission delay caused by the rise in hydraulic oil temperature.

[0009] Preferably, the calculation logic for the normal deviation distance follows the following mathematical relationship: Where D represents the normal deviation distance; This indicates the position of the real-time parameter coordinate point in the reference coordinate system. 3D coordinate components; This indicates the 1st position of the reference point in the reference coordinate system. 3D coordinate components.

[0010] Preferably, for asymmetric off-center loading conditions, the process of obtaining real-time resistance gradient data in step S1 includes: Independently collect the independent resistance parameters of the left and right drive cylinders of the press; Calculate the left-side resistance gradient of the left-side drive cylinder and the right-side resistance gradient of the right-side drive cylinder respectively; Based on the ratio of the left-side resistance gradient to the right-side resistance gradient, a differentiated pressure overshoot compensation amount is matched.

[0011] Preferably, the process of triggering the pressure cutoff signal in step S4 includes: Determine the direction of the gradient deviation between the left and right resistance gradients; Adjusting the signal trigger advance of the left and right pressure relief valves according to the gradient deviation direction delays the pressure relief on the side bearing a larger resistance gradient and allows the side bearing a smaller resistance gradient to relieve pressure earlier, thus using the timing difference of fluid cutoff to offset the physical off-center load torque.

[0012] Preferably, the process of generating the topological reference surface includes: Obtain the boundary of the three-dimensional geometric model of the press mold; Based on the yield strength parameters of the material, mechanical deformation compensation is superimposed on the boundary of the three-dimensional geometric model to generate a topological reference surface with state arbitration capability.

[0013] Preferably, the process of depressurizing the hydraulic circuit in step S4 includes: Send a pulse cutoff signal to the servo pump control system of the pressure regulating unit; The pulse cutoff signal drives the bypass quick relief valve in the hydraulic circuit to open, so as to limit the overshoot of the master cylinder pressure to within the range of 1% to 3%.

[0014] Preferably, the sampling frequency for acquiring real-time resistance gradient data is 10Hz to 50Hz, and the action threshold is dynamically adjusted in real time based on the overshoot margin acquired in each sampling period at the sampling frequency.

[0015] Compared with existing technologies, the adaptive control method for the pressure mechanism of the press of the present invention has the following advantages: 1. In the adaptive control of the pressure mechanism of the press, by synchronously collecting the downward displacement of the slider and the real-time hydraulic volume of the main cylinder, the dynamic resistance gradient reflecting the current plastic deformation characteristics of the material can be extracted in real time. This dynamic resistance gradient is coupled with the fluid hysteresis constant, which characterizes the inherent physical delay of the drive system, so that the system can predict and quantify the pressure overshoot margin caused by fluid compressibility and mechanical inertia in advance. When the static difference between the real-time pressure and the target pressure converges to the pressure overshoot margin, the system triggers the cut-off command of the main control valve and uses the residual fluid momentum in the pipeline to complete the natural rise of the remaining pressure. This control mechanism transforms the unavoidable physical inertia into a power source that accurately approximates the target value, eliminates the pressure penetration phenomenon caused by the phase difference between the control timing and the physical response, and ensures the thickness accuracy of the molded parts and the operating safety of the mold.

[0016] 2. By utilizing pre-set computer-aided design model parameters, a virtual three-dimensional reference space consisting of displacement, pressure, and rheological gradient is constructed within the controller. The measured state vector is then mapped onto the geometric reference surface within this space. This spatial-dimensional topological arbitration mechanism changes the dependence of traditional control logic on linear extrapolation of the one-dimensional time axis. By calculating the Euclidean distance of the real-time rheological trajectory vector projected onto the geometric limit boundary, the system can identify resistance mutations caused by material thickness tolerances or batch hardness fluctuations within an extremely short physical window when the material undergoes nonlinear yielding. This prediction method based on spatial constraints enables the press to have stronger dynamic adaptability to fluctuations in material properties, avoiding the frequent pressure holding instability problems that occur when traditional static control curves face non-uniform materials.

[0017] 3. By extracting the overshoot error between the actual peak pressure and the target pressure of the previous cycle during the return phase of each stamping cycle, and accordingly performing step-by-step adaptive correction of the fluid hysteresis constant, this closed-loop feedback mechanism can dynamically compensate for the viscosity drift caused by the temperature rise of the hydraulic oil during continuous operation, ensuring a high degree of matching between the fluid transmission delay parameters and the real-time physical state of the equipment. This mechanism eliminates the nonlinear interference of environmental factors and equipment temperature rise on the pressing accuracy through parameter self-evolution, maintaining the consistency of forming pressure under continuous operation in all weather conditions. Attached Figure Description

[0018] Figure 1 This is a flowchart of the adaptive control logic for the press based on geometric deviation mapping, as described in this invention. Figure 2 This is a block diagram showing the component composition and data interaction of the adaptive control system of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] It should be noted that all directional and positional terms used in this invention, such as: up, down, left, right, front, back, vertical, horizontal, inner, outer, top, bottom, transverse, longitudinal, center, etc., are only used to explain the relative positional relationship and connection between components in a specific state (as shown in the accompanying drawings). They are only for the convenience of describing this invention and do not require that this invention be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. In addition, the descriptions of "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0021] In the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0022] In the description of this specification, references to the terms "an embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example, and the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0023] The press of the present invention is preferably a direct-drive hydraulic press or a servo hydraulic press with high-precision control capability. The press includes a frame, a hydraulic drive source (such as a hydraulic cylinder) installed in the frame, and a slider driven by the hydraulic drive source to reciprocate linearly along the guide rail. The slider serves as the end-effector for applying pressure, and its bottom end is used to mount the upper mold. During the stamping process, the slider performs a downward forming stroke under the drive of the hydraulic circuit. Its specific function is to convert the fluid power generated by the hydraulic drive source into a plastic deformation load on the material in the mold. At the same time, the slider serves as the physical carrier of displacement and pressure feedback signals. The displacement sensor connected to it provides real-time feedback of the slider's stroke coordinates, and the pressure sensor detects the resistance evolution characteristics generated by the material.

[0024] An adaptive control method for the pressure mechanism of a press includes the following steps: Step S1, collecting the pressure parameters and displacement parameters generated when the slider punches the material during the downward forming stroke, and calculating the slope of the change of the pressure parameters relative to the displacement parameters, so as to obtain real-time resistance gradient data characterizing the evolution law of physical resistance; Step S2: Determine the real-time parameter coordinate points in the reference coordinate system based on the real-time resistance gradient data, and project the real-time parameter coordinate points onto a preset topological reference surface. The topological reference surface is generated by the topological boundary of the press mold and the rheological limit calibration of the material. Step S3: Obtain the normal deviation distance of the real-time parameter coordinate point relative to the topological reference surface, and determine the overshoot allowance of the current pressure state relative to the physical forming limit based on the normal deviation distance. Step S4: Determine whether the overshoot margin has reached the preset action threshold, and trigger the pressure cut-off signal when the overshoot margin reaches the action threshold to drive the pressure regulating unit of the press to complete the hydraulic circuit depressurization; the method uses a reference coordinate system to map the physical overshoot to geometric position deviation, and realizes dynamic adjustment of the downward pressure of the slider based on the feedback logic of the normal deviation distance.

[0025] Preferably, the process of determining the real-time parameter coordinate points in step S2 includes: synchronously acquiring the instantaneous displacement data of the slider and the main cylinder pressure data through the feedback link coupled with the displacement sensor and the pressure sensor; calculating the first derivative of the main cylinder pressure data with respect to the instantaneous displacement data and determining it as the real-time resistance gradient data; and using the real-time resistance gradient data, instantaneous displacement data, and main cylinder pressure data as three-dimensional components to generate real-time parameter coordinate points characterizing the real-time physical state of the press.

[0026] Preferably, the logic for calculating the normal deviation distance in step S3 includes: searching for the surface boundary point on the topological reference surface that is geometrically closest to the real-time parameter coordinate point, and determining the surface boundary point as the reference point; determining the difference vector between the real-time parameter coordinate point and the reference point; performing vector modulus operation on the difference vector, and determining the operation result as the normal deviation distance.

[0027] Preferably, after step S4, a fluid transmission parameter correction step is included: during the return phase of the stamping cycle, the deviation between the actual peak pressure of the stamping cycle and the preset target pressure is obtained; the fluid transmission hysteresis constant of the press is corrected by step superposition based on the deviation value; the action threshold of the next stamping cycle is adjusted using the corrected fluid transmission hysteresis constant to compensate for the pressure transmission delay caused by the rise in hydraulic oil temperature.

[0028] Preferably, the calculation logic for the normal deviation distance follows the following mathematical relationship: Where D represents the normal deviation distance; This indicates the position of the real-time parameter coordinate point in the reference coordinate system. 3D coordinate components; This indicates the 1st position of the reference point in the reference coordinate system. 3D coordinate components.

[0029] Preferably, for asymmetric off-center loading conditions, the process of obtaining real-time resistance gradient data in step S1 includes: independently collecting the independent resistance parameters of the left and right drive cylinders of the press.

[0030] Calculate the left-side resistance gradient of the left-side drive cylinder and the right-side resistance gradient of the right-side drive cylinder respectively; Based on the ratio of the left-side resistance gradient to the right-side resistance gradient, a differentiated pressure overshoot compensation amount is matched.

[0031] Preferably, the process of triggering the pressure cutoff signal in step S4 includes: determining the gradient deviation direction between the left and right resistance gradients; adjusting the signal trigger advance of the left and right pressure relief valves according to the gradient deviation direction, so that the side bearing the larger resistance gradient is depressurized later and the side bearing the smaller resistance gradient is depressurized earlier, thereby using the timing difference of fluid cutoff to offset the physical off-center load torque.

[0032] Preferably, the process of generating the topological reference surface includes: obtaining the three-dimensional geometric model boundary of the press mold; and superimposing mechanical deformation compensation on the three-dimensional geometric model boundary according to the yield strength parameter of the material to generate a topological reference surface with state arbitration capability.

[0033] Preferably, the process of completing the hydraulic circuit depressurization in step S4 includes: sending a pulse cutoff signal to the servo pump control system of the pressure regulating unit; The pulse cutoff signal drives the bypass quick relief valve in the hydraulic circuit to open, so as to limit the overshoot of the master cylinder pressure to within the range of 1% to 3%.

[0034] Preferably, the sampling frequency for acquiring real-time resistance gradient data is 10Hz to 50Hz, and the action threshold is dynamically adjusted in real time based on the overshoot margin acquired in each sampling period at the sampling frequency.

[0035] Example 1: In the continuous deep drawing and stamping process of high-strength steel structural parts for new energy vehicles, there is a thickness tolerance of 0.15mm in the same batch of blank materials, and the local yield strength fluctuates with the ambient temperature. A phase mismatch occurs between the physical inertia of the main drive chain and the nonlinear rheological resistance of the material. The slide moves down to stamp the material and build up pressure. After the high-strength metal enters the plastic deformation stage, its resistance decreases. However, there is a time delay in the release of the compressive potential energy of the hydraulic oil in the drive system pipeline. This physical time delay causes the actual pressure acting on the mold to exceed the target limit, resulting in local thinning of the formed part and alternating impact of the mold frame.

[0036] The feedback link coupled with the displacement sensor and pressure sensor synchronously acquires the instantaneous displacement data of the slider and the main cylinder pressure data. It calculates the first derivative of the main cylinder pressure data with respect to the instantaneous displacement data, obtaining real-time resistance gradient data characterizing the evolution of physical resistance. Using the real-time resistance gradient data, instantaneous displacement data, and main cylinder pressure data as three-dimensional components, it generates real-time parameter coordinate points characterizing the real-time physical state of the press. It extracts the topological reference surface generated by the topological boundary of the press mold and the rheological limit calibration of the material. Specifically, the displacement value of the mold's three-dimensional model at each 0.5mm step position is defined as... The horizontal component of the reference coordinate system is defined as the theoretical pressure value of the material's yield strength at that location, and the vertical component is defined as the slope of the pressure relative to displacement. Using this 3D data, a 320x320 discrete point cloud mapping table is constructed in the controller's memory space as the geometric boundary for state arbitration. The surface boundary point with the closest geometric distance to the real-time parameter coordinate point is searched on the topological reference surface and designated as the reference point. The difference vector between the real-time parameter coordinate point and the reference point is determined, and its vector magnitude is calculated to derive the mathematical relationship. The normal deviation distance, where D represents the normal deviation distance. This represents the i-th dimension coordinate component of the real-time parameter coordinate point in the reference coordinate system; The normal deviation distance represents the i-th dimension coordinate component of the reference point in the reference coordinate system. The feedback logic converts the physical overshoot of the drive system into the geometric position deviation in the reference coordinate system. The system determines the overshoot margin of the current pressure state relative to the physical forming limit based on the normal deviation distance. When the overshoot margin reaches the preset action threshold, a pressure cutoff signal is triggered, sending a pressure cutoff signal to the pressure regulating unit of the press. This drives the bypass pressure relief valve in the hydraulic circuit to open, completing the pressure relief of the hydraulic circuit. The residual momentum of the pipeline after fluid cutoff is used to complete the natural rise of the remaining pressure. The setting logic of the preset action threshold is based on the inherent physical hysteresis characteristics of the main drive chain of the press. The specific setting process is as follows: Before the formal stamping operation, a pre-calibration action is performed, driving the slider to test the sample with multiple sets of incremental initial pressures, and recording the cutoff pressure value at the moment the pressure cutoff valve opens each time. With respect to the actual peak pressure caused by fluid residual momentum The controller calculates the difference between the two. and using the formula This pressure difference is converted into a spatial safety buffer distance within a reference coordinate system, where, Indicates the action threshold. This represents the pre-calibrated hydraulic stiffness mapping coefficient. In this embodiment, by comparing the molding quality under different gradients, when the action threshold is set to 1.2mm, the actual peak pressure exceeding the limit can be accurately converged to 1.2%, effectively balancing the energy cutoff timing and the molding contour fit.

[0037] During the return stroke of the stamping cycle, the deviation between the actual peak pressure and the preset target pressure of the stamping cycle is obtained. The fluid transmission hysteresis constant of the press is corrected based on this deviation. Specifically, in the controller's underlying algorithm, if the actual peak pressure of the current cycle is higher than the preset target pressure, the pressure relief trigger advance time for the next cycle is reduced by 0.01ms; if the actual peak pressure is lower than the preset target pressure, the pressure relief trigger advance time is increased by 0.01ms. The total increment of each correction step is limited to within 2.0ms to prevent control overshoot caused by viscosity drift due to hydraulic oil temperature rise. The corrected fluid transmission hysteresis constant is used to adjust the action threshold for the next stamping cycle. This closed-loop feedback process compensates for the pressure transmission delay caused by continuous hydraulic oil temperature rise. The press performs the above compensation action at a sampling frequency of 10Hz to 50Hz. The overshoot of the master cylinder pressure is limited to the range of 1% to 3%, and the springback deviation of the stamped part is maintained within a certain range. Below 0.05mm; In the fluid transmission parameter correction step, the specific implementation logic of the step-by-step superposition correction is as follows: During the return phase of each stamping cycle, the industrial controller compares the actual peak pressure of the current cycle with the preset target pressure. If the actual peak pressure of the current cycle is higher than the preset target pressure, it is determined that the system has pressure overshoot due to physical inertia. Then, the pressure relief trigger advance time of the next cycle is reduced by a preset fixed step amount so that the pressure cutoff signal is triggered in advance. If the actual peak pressure is lower than the preset target pressure, it is determined that the system depressurizes too early, resulting in insufficient energy. Then, the pressure relief trigger advance time of the next cycle is increased by the same fixed step amount. In order to prevent the control system from overshooting and oscillation due to large viscosity drift caused by hydraulic oil temperature rise, the total step superposition amount of a single correction is set with a safety upper limit. Through this iterative step correction, the system can dynamically update the fluid transmission hysteresis constant, thereby accurately adjusting the action threshold of the next stamping cycle and compensating for the pressure transmission delay.

[0038] Example 2: This example constructs a direct-drive hydraulic press platform with a nominal pressure of 8000kN, equipped with a grating ruler with a resolution of 0.1μm and a piezoelectric pressure sensor with a sampling frequency upper limit of 10kHz, to test the resistance mutation caused by thickness tolerance and the pressure overshoot induced by fluid hysteresis. The sampling frequency setting is limited by the resolution of transient resistance capture and the load limit of the industrial controller bus bandwidth. According to the Nyquist sampling theorem and the millisecond-level time-domain characteristics of plastic yielding of metallic materials, the yield mutation time window of high-strength materials is between 10ms and 20ms. To obtain non-aliased real-time resistance gradient data, the synchronous sampling frequency of the displacement sensor and the pressure sensor needs to be greater than twice the highest frequency component of the resistance mutation. Therefore, the synchronous sampling frequency of the sensor is determined to be 5kHz. The ambient temperature of the test platform is maintained at 40℃ to simulate the temperature rise during continuous operation. The transmission link of the piezoelectric pressure sensor is injected with... The background electromagnetic white noise with an input signal-to-noise ratio of 15dB and the power frequency interference harmonics at a frequency of 50Hz resulted in unprocessed main cylinder pressure data exhibiting sawtooth fluctuations with periodic ripples and random spikes. The main cylinder pressure fluctuation range reached 150.5kN. Instantaneous displacement data and main cylinder pressure data were extracted, and the first derivative of the main cylinder pressure data with respect to the instantaneous displacement data was calculated and processed by low-pass filtering. The specific sampling and filtering strategy was as follows: at a synchronous sampling frequency of 5000Hz, a ring-shaped FIFO buffer with a length of 50 sampling points was opened, with a sliding window length of 10ms and a window sliding every 2ms. The window overlap rate was 80%. The pressure change rate in the buffer was averaged and smoothed to remove the 50Hz power frequency interference and its harmonic noise, and real-time resistance gradient data was obtained. This real-time resistance gradient data filtered high-frequency interference, and its effective signal-to-noise ratio was improved to 45.2dB.

[0039] A comparative verification system was constructed, comprising a control group and an experimental group. The control group employed proportional-integral-derivative (PID) control logic based on a fixed time window. The experimental group extracted a topological reference surface generated by superimposing the three-dimensional geometric model boundary of the press mold and the yield strength parameters of the material with mechanical deformation compensation. Real-time resistance gradient data, instantaneous displacement data, and main cylinder pressure data were used as three-dimensional components to generate real-time parameter coordinate points. The surface boundary point with the closest geometric distance on the topological reference surface was searched as the reference point, and the normal deviation distance was calculated. Where D represents the normal deviation distance, This represents the i-th dimension of the real-time parameter coordinates in the reference coordinate system. This represents the i-th dimension coordinate component of the reference point in the reference coordinate system, and the overshoot margin is calculated according to the formula. Determined, where: R is the overshoot margin, referring to the predicted overshoot value of the load relative to the physical forming limit under the current pressure state; D is the normal deviation distance, referring to the geometric spatial distance between the real-time parameter coordinate point and the topological reference surface. The overshoot conversion factor characterizes the mapping ratio between geometric displacement deviation and pressure overshoot, with a value ranging from 120 to 155. The numerical values ​​were obtained from offline stepped loading experiments. Under different combinations of downward speed and load gradient, the instantaneous pressure value at which the bypass relief valve opened and the peak pressure caused by the residual momentum of the fluid were recorded. The geometric displacement deviation and the pressure rise amplitude were linearly fitted using the least squares method to determine the... In continuous production, the coefficient is gradually corrected by monitoring the residual momentum contribution of each stamping cycle to compensate for changes in mechanical backlash. Three action thresholds of 0.8mm, 1.2mm, and 1.8mm are set to conduct multiple gradient tests. When the action threshold is set to 1.8mm, the residual momentum in the system pipeline is too large when the pressure cutoff signal is triggered, and the actual peak pressure exceeds the limit by 12.4%, resulting in a bottom thinning rate of the formed part exceeding the set target. When the action threshold is reduced to 0.8mm, the hydraulic circuit is cut off, resulting in insufficient fluid momentum to complete the natural rise of the remaining pressure, and the contour fit of the formed part is lower than the standard limit. Under the condition of an action threshold of 1.2mm, after the bypass relief valve of the pressure regulating unit is opened, the main cylinder pressure approaches the target limit, and the actual peak pressure exceeds the limit by 1.2%.

[0040] The strength gradient correlation response of high-strength steel blanks with thickness tolerances of 0.05mm, 0.10mm, and 0.15mm was verified. In the control group with a 0.15mm thickness tolerance, the pressure overshoot margin exceeded the safety limit because the curing time-domain control could not detect sudden changes in material resistance. The experimental group determined the overshoot margin based on the normal deviation distance and corrected the press's fluid transmission hysteresis constant by combining the deviation between the actual peak pressure and the preset target pressure during the return phase. The control group, lacking the fluid transmission parameter correction step, experienced a hydraulic oil temperature rise after 500 consecutive presses. This leads to increased hysteresis, with the peak pressure exceeding the limit drifting from 1.5% to 4.8%. The test group used the corrected fluid transmission hysteresis constant to adjust the action threshold of the next stamping cycle. Within the above thickness tolerance gradient, the peak pressure exceeding the limit was maintained in the range of 1.1% to 1.4%. The geometric measurement of the normal deviation distance and the time compensation loop of the fluid transmission hysteresis constant work together in the physical and temporal domains to resolve the physical conflict between the sudden change in material rheological resistance and the delayed transmission of hydraulic fluid, and to convert the dynamic overshoot of the main drive train into geometric position deviation control in the reference coordinate system.

[0041] Example 3: This example combines Figures 1 to 2 The adaptive control method for the pressure mechanism of the press is explained, such as... Figure 1As shown, step S1 is to collect the pressure and displacement parameters during the slider stamping, calculate the slope of their change, and obtain real-time resistance gradient data. Step S2 is to determine the real-time parameter coordinate points based on the real-time resistance gradient data and project them onto the topological reference surface generated by the mold boundary and the material rheological limit calibration. Step S3 is to obtain the normal deviation distance of the real-time parameter coordinate points relative to the topological reference surface and determine the overshoot allowance of the current pressure state relative to the physical forming limit. Step S4 is to determine whether the overshoot allowance has reached the action threshold. If it has, a pressure cutoff signal is triggered to drive the pressure regulating unit to complete the hydraulic circuit depressurization.

[0042] like Figure 2 As shown, the press contains a left drive cylinder, a right drive cylinder, a slider, and a mold. The press transmits the physical state of the downward forming stroke to the feedback link. The feedback link is equipped with a displacement sensor and a pressure sensor. The feedback link sends the acquired instantaneous displacement data and main cylinder pressure data to the industrial controller. The industrial controller contains a topological reference surface, real-time parameter coordinate points, and normal deviation distance. Based on the calculation results, the industrial controller sends a pulse cutoff signal to the pressure regulating unit. The pressure regulating unit consists of a servo pump control system and a bypass quick pressure relief valve. The pressure regulating unit performs hydraulic circuit pressure relief action on the press.

[0043] Example 4: In the early-stage data modeling and parameter calibration of high-strength steel deep drawing forming, the system constructs a mapping constraint between the physical actuator and the digital space. The industrial controller reads the three-dimensional geometric model of the press mold and extracts discrete geometric boundary coordinate nodes. The material testing unit obtains the nominal yield strength and standard plate thickness of the current batch of high-strength steel. To eliminate the dimensional differences between the sensor dynamic data and the mold static model, the controller pre-establishes a unified three-dimensional parameter reference coordinate system in its internal algorithm. In this reference coordinate system, the first coordinate axis is defined as the displacement component, the second coordinate axis as the pressure component, and the third coordinate axis as the real-time resistance gradient component. The controller utilizes the finite element elastic-plastic deformation... The shape model calculates the stress deformation compensation corresponding to the nominal yield strength and standard plate thickness. The controller adds the stress deformation compensation to the geometric boundary coordinate nodes in a vector superposition manner. The geometric boundary coordinate nodes after the addition of compensation are transformed to a unified three-dimensional parameter reference coordinate system through a mapping function, thereby generating a topological reference surface composed of a spatial mesh in the reference coordinate system. This construction step combines the static physical dimensions of the mold with the dynamic material rheological properties into a topological reference surface. Since the real-time parameter coordinate points generated in step S2 and the topological reference surface generated in this step are under the same three-dimensional component definition of displacement-pressure gradient, the logical basis for calculating the geometric spatial distance between the two in step S3 is ensured.

[0044] Before starting continuous stamping operations, the controller calibrates preset action thresholds to adapt to the physical hysteresis characteristics of the hydraulic lines. The press drives the slider to test the reference material sample with multiple sets of incrementally set initial pressures. At the instant the pressure shut-off valve opens during each test, the displacement sensor and pressure sensor synchronously record the main cylinder pressure and the instantaneous displacement of the slider at the moment of shut-off. The sensors continuously track the pressure rise trajectory caused by the residual momentum of the fluid after the valve opens until the main cylinder pressure reaches the actual peak value. The controller calculates the difference between the actual peak pressure and the main cylinder pressure at the moment of shut-off to obtain the fluid transmission hysteresis constant. The controller then uses a functional relationship... The fluid transmission hysteresis constant is converted into a spatial safety buffer distance in the reference coordinate system, where, Indicates the safe buffer distance in space. This represents the hydraulic stiffness mapping coefficient. The difference between the actual peak pressure and the instantaneous main cylinder pressure at the cutoff point is represented by the controller, which determines the spatial safety buffer distance as the preset action threshold. The geometric node coordinates of the topological reference surface and the numerical calibration of the action threshold provide input parameters for calculating the normal deviation distance. Based on the above spatial boundary and fluid transmission hysteresis constant, the press control system calculates the overshoot margin of the current pressure state relative to the physical forming limit, and sends a pressure cutoff command to the pressure regulating unit according to the action threshold.

[0045] Example 5: When the system faces the initial deployment condition of introducing a new batch of high-strength steel materials, the test unit applies static loads to multiple sets of samples. The sensors synchronously record the elastic deformation displacement value and load tension value before reaching the yield point. The processor solves the ratio of the elastic deformation displacement value to the load tension value to obtain the reference stiffness coefficient. The reference stiffness coefficient and the extracted mechanical backlash parameters of the main drive chain are input into the nonlinear deformation mapping matrix to calculate the stress deformation compensation amount. The system superimposes the stress deformation compensation amount along the normal of the three-dimensional discrete geometric coordinate points and generates a topological reference surface data table in the reference coordinate system. This calibration process establishes the definite boundary constraints of the projection of physical deformation onto the geometric model.

[0046] Temperature sensors collect baseline temperatures of the mold and hydraulic lines. The processor uses these baseline temperatures to locate and match strength reduction factors in a pre-set temperature-hardness decay data table. The dynamic rheological limit is obtained by multiplying the nominal yield strength by the strength reduction factor. This dynamic rheological limit is then imported into the fluid transmission hysteresis correction loop to update the calibration data. Based on the updated topological boundary, the system calculates the normal deviation distance. Where D represents the normal deviation distance, This represents the i-th dimension of the real-time parameter coordinates in the reference coordinate system. This represents the i-th dimension coordinate component of the reference point in the reference coordinate system. The preliminary measurement and data filling steps keep the transient overshoot of the press within the boundary of the safe space mapping grid.

[0047] Example 6: When the system faces the conditions of introducing new batches of materials and ambient temperature drift, the test unit constructs a benchmark reference model in offline state. The heating device heats the standard specimen to discrete temperature nodes from 20℃ to 80℃. The tensile tester measures the actual yield strength of the specimen at each temperature node. The processor calculates the ratio of the actual yield strength to the nominal yield strength to establish the strength reduction factor. The discrete temperature nodes are associated with the strength reduction factor to construct a temperature hardness decay data table. The controller sends a micro-displacement pulse signal with a step size of 0.01mm to the servo motor. The displacement difference between the motor output driving torque and the moment when the displacement sensor outputs an effective signal is quantified into the mechanical backlash parameter of the main transmission chain. The pre-calibration operation constructs the determined physical boundary constraints.

[0048] The testing unit applies a static load to the material sample and records the elastic deformation displacement and load tension values. The processor calculates the quotient of the two to obtain the reference stiffness coefficient. The controller inputs the reference stiffness coefficient and mechanical backlash parameters into a mapping matrix to calculate the stress deformation compensation. The compensation is then superimposed along the normal of the geometric coordinate points to generate a topological reference surface. A temperature sensor collects the real-time ambient temperature. The processor addresses and matches the strength reduction factor in the data table and multiplies it by the nominal yield strength to obtain the dynamic rheological limit. The system calculates the normal deviation distance based on the updated topological reference surface. Where D represents the normal deviation distance, Represents the real-time parameter coordinate point components. The reference point component is represented by an offline data filling mechanism to eliminate the blind spot in the overshoot detection of the press master cylinder.

[0049] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A method for adaptive control of the press mechanism of a press, characterized in that, Includes the following steps: Step S1: Collect the pressure parameters and displacement parameters generated when the slider presses the material during the downward forming stroke, and calculate the slope of the change of the pressure parameters relative to the displacement parameters to obtain real-time resistance gradient data that characterizes the evolution law of physical resistance. Step S2: Determine the real-time parameter coordinate points in the reference coordinate system based on the real-time resistance gradient data, and project the real-time parameter coordinate points onto a preset topological reference surface. The topological reference surface is generated by the topological boundary of the press mold and the rheological limit calibration of the material. Step S3: Obtain the normal deviation distance of the real-time parameter coordinate point relative to the topological reference surface, and determine the overshoot allowance of the current pressure state relative to the physical forming limit based on the normal deviation distance. Step S4: Determine whether the overshoot margin has reached the preset action threshold, and trigger the pressure cut-off signal when the overshoot margin reaches the action threshold to drive the pressure regulating unit of the press to complete the hydraulic circuit depressurization; the method uses a reference coordinate system to map the physical overshoot to geometric position deviation, and realizes dynamic adjustment of the downward pressure of the slider based on the feedback logic of the normal deviation distance.

2. The press machine adaptive control method of claim 1, wherein, The process of determining the real-time parameter coordinates in step S2 includes: The instantaneous displacement data of the slider and the pressure data of the master cylinder are acquired synchronously through a feedback link that couples the displacement sensor and the pressure sensor. Calculate the first derivative of the master cylinder pressure data with respect to the instantaneous displacement data, and determine it as the real-time resistance gradient data; Real-time resistance gradient data, instantaneous displacement data, and main cylinder pressure data are used as three-dimensional components to generate real-time parameter coordinate points that characterize the real-time physical state of the press.

3. The press machine adaptive control method of claim 1, wherein, The logic for calculating the normal deviation distance in step S3 includes: Search for the surface boundary point on the topological reference surface that is geometrically closest to the real-time parameter coordinate point, and determine the surface boundary point as the reference point; Determine the difference vector between the real-time parameter coordinate points and the reference point; Perform vector magnitude operation on the difference vector and determine the result as the normal deviation distance.

4. The adaptive control method for the pressure mechanism of the press according to claim 1, characterized in that, Step S4 is followed by a fluid transmission parameter correction step: During the return stroke of the stamping cycle, the deviation between the actual peak pressure of the stamping cycle and the preset target pressure is obtained. The fluid transmission hysteresis constant of the press is corrected by step superposition based on the deviation value; The modified fluid transmission hysteresis constant is used to adjust the action threshold of the next stamping cycle to compensate for the pressure transmission delay caused by the rise in hydraulic oil temperature.

5. The press machine adaptive control method of claim 3, wherein, The calculation logic for the normal deviation distance follows the following mathematical relationship: Where D represents the normal deviation distance; This indicates the position of the real-time parameter coordinate point in the reference coordinate system. 3D coordinate components; This indicates the 1st position of the reference point in the reference coordinate system. 3D coordinate components.

6. The press machine adaptive control method of claim 1, wherein, For asymmetric off-center loading conditions, the process of obtaining real-time resistance gradient data in step S1 includes: Independently collect the independent resistance parameters of the left and right drive cylinders of the press; Calculate the left-side resistance gradient of the left-side drive cylinder and the right-side resistance gradient of the right-side drive cylinder respectively; Based on the ratio of the left-side resistance gradient to the right-side resistance gradient, a differentiated pressure overshoot compensation amount is matched.

7. The press machine adaptive control method of claim 6, wherein, The process of triggering the pressure cutoff signal in step S4 includes: Determine the direction of the gradient deviation between the left and right resistance gradients; Adjusting the signal trigger advance of the left and right pressure relief valves according to the gradient deviation direction delays the pressure relief on the side bearing a larger resistance gradient and allows the side bearing a smaller resistance gradient to relieve pressure earlier, thus using the timing difference of fluid cutoff to offset the physical off-center load torque.

8. The press machine adaptive control method of claim 1, wherein, The process of generating the topological reference surface includes: Obtain the boundary of the three-dimensional geometric model of the press mold; Based on the yield strength parameters of the material, mechanical deformation compensation is superimposed on the boundary of the three-dimensional geometric model to generate a topological reference surface with state arbitration capability.

9. The press machine adaptive control method of claim 1, wherein, Step S4, which involves depressurizing the hydraulic circuit, includes: Send a pulse cutoff signal to the servo pump control system of the pressure regulating unit; The pulse cutoff signal drives the bypass quick relief valve in the hydraulic circuit to open, so as to limit the overshoot of the master cylinder pressure to within the range of 1% to 3%.

10. The adaptive control method for the pressure mechanism of the press according to claim 1, characterized in that, The sampling frequency for acquiring real-time resistance gradient data is 10Hz to 50Hz, and the action threshold is dynamically adjusted in real time based on the overshoot margin acquired in each sampling period at the sampling frequency.

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