A springback compensation calculation and forming method for multi-step composite stamping features

Abstract

The present application provides a kind of multi-step composite stamping feature springback compensation calculation and forming method, it is related to sheet metal stamping forming technical field, include: to the pre-bending forming processing of the stamping material belt to be executed, generate multi-step pre-bending blank;To pre-bending blank executes step-by-step round operation, generates round transition piece;According to static springback numerical value, finishing sizing and corner shaping operation are executed to transition piece.The method also includes dynamic compensation control: obtain adjacent step size correlation parameters and continuous operation batch parameters;According to size correlation parameters, stress coupling coefficient is established;According to batch parameter, compensation attenuation factor is generated;Coefficient, factor and static springback numerical value are fused and calculated, and target springback compensation instruction is generated;According to target instruction, the compensation shaping action of subsequent batch is controlled.The present application can compensate the dynamic error accumulation generated in long-term processing, and improve the size consistency of multi-step finished product forming.

Description

Technical Field

[0001] This invention relates to the field of sheet metal stamping technology, and in particular to a springback compensation calculation and forming method for multi-step composite stamping features. Background Technology

[0002] Multi-step structures with rounded edges are widely used in fluid pipelines and mechanical transmission mechanisms. These parts typically contain stepped regions of varying diameters and wall thicknesses arranged along the axis. In industrial processing, metal strips are often pre-bent and rolled sequentially through stamping processes to achieve the rounded closure of the structure. After the metal material undergoes plastic deformation under stress, its internal elastic recovery tendency causes the physical dimensions of the demolded part to spring back. To control dimensional deviations, the industry often extracts static springback values ​​based on finite element static simulations or single-trial mold measurements during the initial mold design phase. Introducing this springback value as a compensation factor into the control of the mold closing depth ensures that the formed parts basically achieve the target closed state and meet the dimensional design requirements during small-batch production.

[0003] In long-cycle, high-volume stamping production, the individual steps of multi-step parts possess different moments of inertia and bending stiffness. When adjacent steps undergo bending deformation, residual shear stress is transversely transmitted. Simultaneously, as the number of strokes increases with continuous operation of the forming equipment, the heat accumulation generated by friction between the die surface and the metal material causes inward thermal expansion of the closed cavity. Long-term physical friction contact also leads to microscopic spalling and wear on the die's inner wall. The dynamic drift effect of the die's physical boundary dimensions interacts with the stress-deformation interference unique to multi-step structures, resulting in a constantly changing actual springback compensation required to maintain the target product dimensions. Relying on initially set static constant parameters cannot be adjusted according to equipment operating conditions degradation and multi-step local deformation interference, easily affecting the dimensional consistency and forming accuracy of parts in the same batch during continuous, high-volume stamping operations. Summary of the Invention

[0004] The purpose of this invention is to provide a springback compensation calculation and forming method for multi-step composite stamping features, in order to solve the problem pointed out in the background art that it is difficult to cope with the lateral interference of residual stress inside the multi-step and the physical boundary dimension drift caused by the long-term operation of the stamping die, which in turn affects the dimensional consistency of multi-step formed parts in the same batch of continuous processing.

[0005] This invention provides a springback compensation calculation and forming method for multi-step composite stamping features, comprising the following steps:

[0006] The strip to be stamped is pre-bent to form a multi-step pre-bent blank.

[0007] Perform a step-by-step rolling operation on the multi-step pre-bent blank to generate a rounded transition part;

[0008] Based on the static springback value, the rounded transition piece is subjected to finishing and sizing processes as well as corner shaping operations to generate a multi-step rounded finished product.

[0009] The method also includes a dynamic compensation control step:

[0010] Obtain the correlation parameters between adjacent step dimensions and the parameters of continuous operation batches;

[0011] The stress coupling coefficient is established based on the correlation parameters of the adjacent step dimensions;

[0012] A compensation attenuation factor is generated based on the continuous operation batch parameters;

[0013] The stress coupling coefficient, the compensation attenuation factor, and the static rebound value are fused together to generate a target rebound compensation command;

[0014] The compensation and shaping actions of the finishing and sizing process and the corner shaping operation in subsequent batches are controlled according to the target springback compensation command.

[0015] Optionally, the pre-bending forming process of the strip to be stamped to generate a multi-step pre-bent blank includes:

[0016] The raw material is precisely cut to suppress micro-cracks at the material edges, and the strip to be stamped is obtained.

[0017] Calculate the unfolded dimension parameters corresponding to each independent step in the strip to be stamped;

[0018] The strip to be stamped is subjected to segmented bending operation according to the unfolded size parameters to generate the multi-step pre-bent blank in an unfolded state.

[0019] Optionally, the step-by-step rolling operation on the multi-step pre-bent blank to generate a rounded transition part includes:

[0020] The multi-step pre-bending blank is divided into multiple forming stress nodes;

[0021] Rolling forming force is applied to the multiple forming force nodes in a set sequence.

[0022] Set the position of the rounded joint generated in the previous rounding step as the forming starting point of the subsequent rounding step.

[0023] By applying the rolling forming force multiple times to disperse the deformation stress of the material, the risk of cracking of the part caused by excessive local sudden stress is reduced, thus generating the round transition part.

[0024] Optionally, the step of performing finishing and sizing processing and corner shaping operations on the rounding transition piece based on the static springback value to generate a multi-step rounding finished product includes:

[0025] Retrieve the 3D contour mold part model;

[0026] The three-dimensional contour mold is controlled to apply a forced clamping correction operation to all step areas based on the three-dimensional contour mold part model;

[0027] In the forced closing correction operation, the static rebound value is superimposed to close and compress the corner areas corresponding to all steps, mechanically correct the roundness and closing gap, and obtain the multi-step rounded finished product that has reached the target closed state.

[0028] Optionally, obtaining the correlation parameters of adjacent step dimensions and the parameters of continuous operation batches includes:

[0029] Extract the diameter ratio and wall thickness difference of the pairs of adjacent steps;

[0030] The diameter ratio and the wall thickness difference are defined as the adjacent step size correlation parameters;

[0031] Obtain the current cumulative stroke cycle value of the forming equipment, and establish the current cumulative stroke cycle value as the continuous operation batch parameter.

[0032] Optionally, establishing the stress coupling coefficient based on the adjacent step size correlation parameters includes:

[0033] The lateral transmission strength of residual shear stress generated during the multi-step composite encirclement process is evaluated using the correlation parameters of adjacent step dimensions.

[0034] A nonlinear mapping rule is constructed based on the lateral transmission intensity of the residual shear stress;

[0035] The stress coupling coefficient, which characterizes the degree of mutual interference between steps, is calculated using the nonlinear mapping rule.

[0036] Optionally, generating the compensation attenuation factor based on the continuous operation batch parameters includes:

[0037] Extract the estimated values ​​of mold heat accumulation and mechanical wear corresponding to the parameters of the continuous operation batch;

[0038] Substitute the estimated values ​​of mold thermal accumulation and mechanical wear into the preset life decay model;

[0039] The preset lifetime decay model is used to output the compensation decay factor to offset the accumulation of dynamic errors.

[0040] Optionally, the step of fusing the stress coupling coefficient, the compensation attenuation factor, and the static rebound value to generate the target rebound compensation command includes:

[0041] The static rebound value is multiplied by the stress coupling coefficient to obtain the primary compensation parameters;

[0042] The primary compensation parameters are combined with the compensation attenuation factor to perform a correction and reduction operation to obtain the target compensation offset.

[0043] The target compensation offset is encapsulated into the control protocol data stream to generate the target rebound compensation command.

[0044] Optionally, before performing a correction and reduction operation by combining the primary compensation parameters with the compensation attenuation factor to obtain the target compensation offset, the following steps are included:

[0045] Determine whether the primary compensation parameter exceeds the preset material forming limit safety threshold;

[0046] If the primary compensation parameter exceeds the preset material forming limit safety threshold, the primary compensation parameter will be truncated to the preset material forming limit safety threshold, and an over-limit warning action will be triggered.

[0047] Optionally, the compensation shaping action of controlling the finishing and sizing process and the corner shaping operation in subsequent batches according to the target springback compensation command includes:

[0048] Analyze the position offset data and pressure adjustment data carried by the target rebound compensation command;

[0049] The position offset data is sent to the position control terminal to guide the dynamic adjustment of the mold closing depth;

[0050] The pressure adjustment data is sent to the pressure control terminal to realize the dynamic application of the pressure for closing the gap.

[0051] The present invention has achieved the following beneficial effects:

[0052] The method provided by this invention establishes a stress coupling coefficient by extracting the diameter ratio and wall thickness difference between adjacent steps, and evaluates the lateral transmission effect of residual shear stress between different steps in composite rounding processing, taking into account the deformation interference caused by the difference in material bending stiffness. Based on this, the method uses continuous batch parameters to generate a compensation attenuation factor, incorporating the thermal expansion of the die and the tendency of inner wall contact wear caused by long-term stamping operation into the calculation model. By introducing the stress coupling coefficient and the compensation attenuation factor into the fusion calculation process of the initial static springback value, this method generates a target springback compensation command that dynamically evolves with the processing state, and guides the adjustment of the die closing depth and docking pressure in subsequent continuous processing operations. This compensation mechanism, which integrates equipment physical loss and structural deformation interference factors on the original static benchmark, enables the forming equipment to fine-tune control parameters according to the stress transmission characteristics of multi-step parts and the evolution of the die's own boundary dimensions, maintaining the dimensional consistency of multi-step products in long-cycle continuous forming processes.

[0053] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0054] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0055] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0056] Figure 1 This is a structural block diagram of an automated stamping forming system provided in an embodiment of the present invention;

[0057] Figure 2 The flowchart illustrates the springback compensation calculation and forming method for a multi-step composite stamping feature provided in this embodiment of the invention.

[0058] Figure 3 This is a flowchart illustrating the specific steps involved in pre-bending the strip to be stamped, as provided in an embodiment of the present invention.

[0059] Figure 4 This is a flowchart illustrating the specific steps of performing a step-by-step rolling operation on a multi-step pre-bent blank, as provided in an embodiment of the present invention.

[0060] Figure 5 A flowchart illustrating the logic of generating target rebound compensation instructions and determining safety, provided in an embodiment of the present invention.

[0061] Figure 6 A flowchart illustrating the steps of parallel execution of control compensation shaping actions provided in an embodiment of the present invention. Detailed Implementation

[0062] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0063] This application discloses a springback compensation calculation and forming method for multi-step composite stamping features. The method relies on an automated stamping forming system comprising a strip servo feeding mechanism, a progressive forming die assembly, a CNC stamping machine body, a multi-dimensional sensor network, and an industrial main control computer. Its structure is as follows: Figure 1 As shown. The springback compensation calculation and forming method for the multi-step composite stamping feature includes a preliminary forming step and a dynamic compensation control step, and its overall process is as follows. Figure 2 As shown, the specific technical steps include the following:

[0064] Step S100: Perform pre-bending forming on the strip to be stamped to generate a multi-step pre-bent blank.

[0065] In this embodiment, as Figure 3 As shown, step S100 includes: performing precision blanking on the original material to suppress micro-cracks at the material edge, and obtaining the strip to be stamped; calculating the unfolded dimension parameters corresponding to each independent step in the strip to be stamped; performing a segmented bending operation on the strip to be stamped according to the unfolded dimension parameters to generate the multi-step pre-bent blank in an unfolded state.

[0066] Understandably, in multi-stage composite stamping operations, the initial edge morphology generated by the blanking process is related to the forming parameters in the curvature variation region. Conventional wide-gap blanking operations create fracture zones on the separation surface, accompanied by the generation of grain boundary microcracks. When the strip enters the bending and tension stage, these microcracks act as stress concentration sources at the joint. Precision blanking of the original material alters the stress distribution in the blanking area, increasing the proportion of bright bands on the sheared surface.

[0067] Specifically, the precise blanking process of the raw material to suppress micro-cracks at the material edges and obtain the strip to be stamped includes: controlling the servo stepping feeding mechanism of the stamping machine to transport the raw material of a preset thickness specification to the precision blanking die station. Specifically, the thickness parameter of the raw material of the preset thickness specification is set to 0.1 mm to 2.0 mm; the shear strength parameter of the raw material is set to 200 MPa to 600 MPa. Based on the thickness parameter and shear strength parameter of the raw material, the single-sided blanking clearance parameter between the punch and the bottom die is set. Specifically, the formula for determining the single-sided blanking clearance parameter is:

[0068] ;

[0069] in, This refers to the single-sided punching clearance parameter, in millimeters. The thickness parameter is in millimeters. This is the gap proportioning factor, which has no unit and its value is based on the shear strength parameter. Dynamically determined: when ( When the unit is megapascal (MPa), The value ranges from 0.005 to 0.010; when ( When the unit is megapascal (MPa), The value ranges from 0.010 to 0.020. Gap proportionality coefficient. Based on shear strength parameters in each corresponding interval Perform linear mapping solution: when At that time, according to the formula Calculations show that; when At that time, according to the formula The calculation shows that the single-sided punching gap parameter is constrained within a preset numerical range of the original material thickness parameter. Specifically, the preset numerical range is defined as 0.5% to 2.0%.

[0070] Before the punch moves downwards and contacts the raw material, the toothed pressure plate inside the die applies a vertical clamping force to the raw material around the cutting edge, and works in conjunction with the bottom reverse ejector block to apply a back-supporting force. Specifically, the vertical clamping force... The algebraic calculation formula is:

[0071] ;

[0072] The back support force The algebraic calculation formula is:

[0073] ;

[0074] in, This refers to the physical perimeter parameter of the cutting edge, in millimeters; This is a thickness parameter, in millimeters; The shear strength parameter is expressed in megapascals (MPa); in the formula... This is an empirical constant for the clamping force, dimensionless, and fixed at 0.15. The lifting force is an empirical constant, dimensionless, and fixed at 0.08; the resulting force and All units are Newtons. The derivation of the above formulas for calculating the clamping force and the back-lifting force is based on the triaxial hydrostatic stress state theory in metal plastic forming. The product term in the formula... The theoretical physical limit of shear resistance is represented by the boundary of the shear separation surface. Constants of 0.15 and 0.08 are introduced to apply a downward normal force of 15% and an upward reaction force of 8% of the theoretical failure limit shear force to the cutting edge region. This distribution reconstructs a triaxial forced compressive stress field at the microscopic local level of the material grain boundaries, thereby counteracting the tensile stress peaks that accompany shearing and effectively suppressing edge warping and tearing and grain boundary microcracks from a stress state perspective. Under the combined action of the clamping force and the opposing lifting force, the original material forms a triaxial compressive stress state in the cutting edge region. As the punch continues to descend and apply shear force, the triaxial compressive stress state limits the rise of tensile stress, prompting the original material to undergo plastic shear slip. The increase in the depth of plastic shear slip increases the proportion of shear bright bands on the separation surface. The punching closing action is controlled until the original material separates, obtaining the punched strip with eliminated edge microcracks.

[0075] Further, the calculation of the unfolded dimension parameters corresponding to each independent step in the strip to be stamped includes: obtaining a digital three-dimensional contour model of the target multi-step rounded product, and extracting the target inner diameter value, target outer diameter value, and local thickness value corresponding to each independent step from the digital three-dimensional contour model. When the multi-step structure undergoes plastic bending deformation, the neutral layer of the material shifts inward. The yield strength parameter and elastic modulus parameter corresponding to the strip to be stamped are extracted from the material mechanics parameter database. For each independent step, the corresponding target inner diameter value and local thickness value are substituted into the neutral layer shift prediction model, and combined with the yield strength parameter and elastic modulus parameter, the neutral layer displacement coefficient corresponding to each independent step is calculated. Specifically, the core derivation formula of the neutral layer shift prediction model is:

[0076] ;

[0077] in, The displacement coefficient of the neutral layer is unitless. The actual physical radius of the inner side corresponding to the target inner diameter value (i.e., half of the inner diameter value), in millimeters; The local thickness value is in millimeters; The yield strength parameter is expressed in megapascals (MPa). The elastic modulus parameter is given in megapascals (MPA). This is the neutral layer reference constant, which has no unit and is set to 0.5. This is an empirical material strain hardening correction factor, dimensionless, with a value range of 0.05 to 0.12; It is the natural logarithm function. The system will calculate the result. The effective values ​​are forcibly constrained to be between 0.25 and 0.50. The core derivation of the neutral layer offset prediction model is based on the asymmetric distribution of elastoplastic bending strain. There is no unit aspect ratio term. Characterizing the relative geometric depth of plastic deformation, strain term Characterizing the elastic potential of materials; the model utilizes the natural logarithm function. The nonlinear physical trajectory of the gradual inward shift and decay of the neutral layer due to the asymmetry of the yield point between the inner compressive plastic zone and the outer tensile plastic zone of the metal was accurately characterized. The control system incorporates empirical material strain hardening correction factors. The standard elongation after fracture test constant of the target material at the factory. (Expressed as a unitless decimal percentage) Establish analytic mapping: Define the associative equation When the calculated result is greater than 0.12, a boundary truncation of 0.12 is directly performed to ensure a stable mathematical displacement solution loop.

[0078] The absolute value of the neutral layer offset is obtained by multiplying the local thickness value by the neutral layer displacement coefficient. Specifically, the absolute value of the neutral layer offset... The algebraic formula for obtaining it is:

[0079] ;

[0080] in The unit is millimeters. The actual physical radius of the inner side of the target is algebraically calculated using the absolute value of the neutral layer offset to obtain the bending neutral layer diameter value corresponding to each independent step. Specifically, the bending neutral layer diameter value... The geometric mapping formula is:

[0081] ;

[0082] in The unit is millimeters. The perimeter arc length of each independent step under a set condition is calculated by multiplying the diameter of the curved neutral layer by a preset pi constant. Specifically, the perimeter arc length value... The calculation formula is:

[0083] ;

[0084] The preset pi constant The value is fixed in the underlying processor register as a unitless constant of 3.14159; The unit is millimeters.

[0085] The perimeter arc length values ​​are added together with the stretch allowance parameters reserved in the transition area between adjacent steps. Specifically, the stretch allowance parameters... The evaluation formula is:

[0086] ;

[0087] in, and The values ​​are the bending neutral layer diameters of the adjacent anterior and posterior steps, respectively, in millimeters. The elongation constant of the material is calibrated; it is dimensionless and its value range is set to 0.01 to 0.03. The unit is millimeters. The mechanical principle behind the formula for calculating the stretch allowance parameter is that: the moment of inertia and bending stiffness of adjacent steps in a multi-step blank differ significantly. When the die forces the blank to roll it into a circle, the low bending stiffness area will be subjected to parasitic pull-out caused by the high stiffness step, resulting in unexpected axial elongation and thinning; the formula uses... Capture the abrupt change in physical stiffness caused by this diameter drop. For the elongation constant... The acquisition of this data is based on a system-level foundation that is fixed at the nominal local thickness of the board material. The reverse mapping formula: The logic dictates that the greater the material thickness, the stronger its ability to resist lateral tensile distortion. This ultimately generates the unfolded dimension parameters corresponding to each independent step. Specifically, the unfolded dimension parameters... The formula for summation is:

[0088] ;

[0089] in The unit is millimeters.

[0090] Further, the step of performing segmented bending operations on the strip to be stamped based on the unfolded size parameters to generate a multi-step pre-bent blank in an unfolded state includes: sending the unfolded size parameters to the CNC mainboard of the stamping machine, converting them into step feed drive coordinate commands and die bending punch stroke control commands. Inside the die cavity of the pre-bending station, a group of forming punches driven independently by a servo mechanism is arranged along the stamping feed direction. The control system drives the forming punch group to apply downward pressure torque to each independent step area of ​​the strip to be stamped in sequence according to a preset spatial timing. The front forming punch preferentially applies forming bending moment to the first step area, causing the first step area to undergo initial bending deformation; after a preset clock time delay, specifically, the preset clock time delay The solution formula is:

[0091] ;

[0092] in, The delay time is in seconds. The physical center distance between the front forming punch and the rear forming punch is in millimeters. The linear velocity feedback parameter for the servo stepper feed mechanism is expressed in millimeters per second (mm / s). The mechanical dwell time constant for the control system response, in seconds, is set to 0.01 to 0.03. (Time constant) Based on the real-time feed linear speed feedback of the machine tool spindle With the maximum permissible safe linear speed of CNC The dynamic solution equation was established: This allows the system to intelligently extend or shorten the dwell buffer according to the real-time production line speed ratio in the workshop, effectively compensating for acceleration and deceleration disturbances of the feed motor and bus parsing lag. The rear-side forming punch applies a forming bending moment to the tail-end stepped area of ​​the strip to be punched, causing the tail-end stepped area to undergo initial bending deformation.

[0093] The downward stopping point position of each forming punch is independently controlled by the unfolded dimension parameters. Specifically, the downward stopping point position controlled by the independent limits... The formula for establishing is:

[0094] ;

[0095] in, The unit is millimeters; Reference depth coordinate parameters for machine tool calibration, in millimeters; The unfolded dimension parameter is in millimeters; The reference cross-sectional arc length parameter is in millimeters. The lateral physical tilt angle parameter of the forming punch, in degrees; The tangent trigonometric function is used. The segmented loading operation avoids the mechanical interference caused by the difference in deformation rate between different step areas, so that the strip to be stamped is transformed into a multi-step entity with a continuously bent cross-section, generating the multi-step pre-bent blank in an unfolded state.

[0096] Step S200: Perform a step-by-step rolling operation on the multi-step pre-bent blank to generate a rounded transition part.

[0097] In this embodiment, as Figure 4 As shown, step S200 includes: dividing the multi-step pre-bent blank into multiple forming force nodes; applying rolling forming force to the multiple forming force nodes in a set sequence; setting the position of the rounded joint generated in the previous rolling step as the forming starting point of the subsequent rolling step; and dispersing the material deformation stress by applying rolling forming force multiple times to generate the rounded transition piece.

[0098] Understandably, when performing roll forming on structures with abrupt dimensional changes, adjacent independent steps possess different bending stiffness parameters. If simultaneous centripetal extrusion is applied, steps with higher stiffness will push against steps with lower stiffness, inducing axial slip flow in the material. Discretizing the roll forming process into multiple forming force nodes in the spatial dimension and sequentially loading them in stages over time can guide controlled plastic slip in the metal lattice. Using the completion position of the preceding forming action as the spatial starting point for subsequent deformation allows for a smooth transition of deformation energy.

[0099] Specifically, dividing the multi-step pre-bent blank into multiple forming stress nodes includes: calling a digital mechanics analysis module to obtain the surface geometric topology mesh data of the multi-step pre-bent blank; performing region discretization mesh boundary division processing on the lateral extension arc surface of the multi-step pre-bent blank; specifically, the region discretization mesh boundary division processing adopts a hexahedral three-dimensional solid mesh division algorithm, the global basic spacing of the mesh nodes is calibrated to 0.5 mm, and local mesh refinement is performed in the physical connection transition area of ​​steps with different diameters, with the local mesh spacing fixed at 0.1 mm; extracting the discrete distribution curve of the difference between the initial pre-bending curvature parameter and the target wrapping diameter parameter; specifically, the deformation gradient parameter on the curve. Physically defined as the rate of change of the local principal curvature relative to the arc length, its partial derivative formula is:

[0100] ;

[0101] in, The principal curvature parameter of the corresponding mesh node, in millimeters (reciprocal). ); The arc length along the curved surface is a variable, in millimeters; It is a partial derivative operator; The unit is the negative square of millimeters ( The system locks the spatial coordinates where the deformation gradient parameter is greater than a preset gradient threshold. Specifically, the preset gradient threshold for the deformation gradient parameter is set as follows: The analysis module extracts and locks... The grid nodes directly serve as the forming force nodes. On the cross-sectional contour trajectory and axial step arrangement trajectory of the multi-step pre-bent blank, the forming force nodes are distributed in the edge extension area, bottom smooth transition area, and intersection area of ​​steps with different diameters of each independent step.

[0102] Furthermore, applying the rolling forming force to the multiple forming force nodes according to a set sequence includes: within the rolling processing area of ​​the mold, drive-side slider assemblies and forming push assemblies corresponding to the coordinates of each forming force node are arranged in an array. The entry timing of each drive-side slider assembly is controlled by a machine tool spindle synchronous encoder signal generator. Specifically, the underlying control logic of the entry timing is set as follows: real-time reading of the feedback absolute rotation angle of the machine tool spindle synchronous encoder; when the feedback absolute rotation angle reaches the range of 90 degrees to 140 degrees, a high-level pulse is output to trigger the front side slider assembly to enter; when the feedback absolute rotation angle reaches the range of 150 degrees to 210 degrees, a high-level pulse is output to trigger the rear side forming push assembly to enter; the physical misalignment of the angle range of the electrical signals ensures that the rolling load does not interfere or overlap in the time domain. The control module drives the front-side sliding block assembly to apply mechanical thrust along a preset guide rail to the forming force nodes distributed on the outer edge, forcing the open edge of the multi-step pre-bent blank to undergo initial curling plastic deformation towards the central axis. After completing the initial deformation, the feeding system conveys the material to the next processing station. The control module then drives the rear-side forming push assembly to apply subsequent curling forming force to the forming force nodes distributed in the inner geometric transition region, forcing the metal material to bend and slide inward.

[0103] Further, setting the position of the rounding seam generated in the previous rounding step as the forming starting point of the subsequent rounding step includes: after completing the initial rounding transformation, the folded edge of the multi-step pre-bent blank forms an incompletely closed primary rounding seam. A high-precision vision capture lens module acquires the spatial coordinate mapping position data of the primary rounding seam. Specifically, the digital algorithm flow for acquiring the spatial absolute coordinate mapping position data using the high-precision vision capture lens module is as follows: A two-dimensional grayscale image matrix containing the seam area is acquired using an industrial CCD area array camera; the Canny edge detection operator is called to calculate the pixel gradient of the image matrix, extracting the set of pixel coordinates representing the discontinuous features of the seam edge; the offline calibrated camera intrinsic and extrinsic affine transformation matrix is ​​called, and the set of pixel coordinates is multiplied by the extrinsic transformation matrix to inversely map and generate three-dimensional spatial absolute coordinate data in the machine tool mechanical coordinate system. The units for the coordinate components are all in millimeters. During the rolling operation in the subsequent stage, the control program fine-tunes the coordinates of the force-bearing contact surface of the rear forming and pressing assembly, ensuring that the force-bearing contact surface conforms to the metal interface of the initial rounding joint edge generated by the preceding rolling step. Specifically, the servo control program sets the current control reference absolute coordinates of the rear mold pressing assembly... The extracted three-dimensional absolute coordinate data of the joint Perform vector subtraction to calculate the spatial position deviation vector. The units of the deviation vector are all millimeters. This spatial position deviation vector is converted into a position offset compensation pulse output to the servo motor, and the geometric coordinate deviation is offset through closed-loop feedback. The mechanical contact area between the subsequent forming and pressing component and the edge interface of the primary rounding joint is used as the forming starting point for applying bending moment in the new round.

[0104] Furthermore, the method of dispersing material deformation stress by applying multiple rolling forming forces to reduce the risk of part cracking due to excessive local stress, and generating the rounded transition part, includes: through the coordinated stamping actions of multiple consecutive workstations, the total deformation process of the metal material is divided into a preset number of deformation increment processes. In each round of deformation, the applied rolling forming force load is constrained within the envelope of the tensile fracture strength of the metal material. Specifically, the mechanical boundary inequality of the physical fracture failure tensile strength envelope is expressed as:

[0105] ;

[0106] Among them, the rolling forming force load is recorded in real time. The unit is Newton; This is the nominal tensile strength parameter of metallic materials, expressed in megapascals (MPa). This represents the minimum cross-sectional area of ​​the stressed entity corresponding to the current stressed node, expressed in square millimeters. To prevent physical fracture, a constant safety reduction coefficient is used, which is dimensionless and fixed at 0.80 in the control system. After multiple step-by-step curling actions, a metal solid model with a multi-step cylindrical outline is formed, which is defined as the rounded transition component.

[0107] Step S300: Perform finishing and sizing processing and corner shaping on the rounded transition part according to the static springback value to generate a multi-step rounded finished product.

[0108] In this embodiment, step S300 includes: retrieving the three-dimensional contouring mold part model; controlling the three-dimensional contouring mold to apply a forced closing correction operation to all step areas based on the three-dimensional contouring mold part model; superimposing static springback values ​​during the forced closing correction operation to close and compress the corner areas corresponding to all steps, correcting the roundness and closing gaps, and obtaining a multi-step rounded finished product in the target closed state.

[0109] It is understandable that for multi-step circular parts, the asymmetrical distribution of structural mass and the different bending stiffness values ​​of each step can lead to dimensional deformation caused by unloading springback. The springback displacement for a specific metal grade and geometric characteristics can be obtained through static simulation, and the calculated compensation reference constant parameter is defined as the static springback value. Specifically, the static springback value includes the radial springback compensation amount. With angle rebound compensation The radial rebound compensation amount The formula for obtaining the benchmark is:

[0110] ;

[0111] in, The unit is millimeters; The target nominal outer diameter parameter for an independent step, in millimeters; The centripetal bending moment constant is measured by static simulation or calibration, and its unit is Newton-millimeter (N·mm). ); The equivalent arc length of the step in the circumferential direction is a parameter in millimeters. This refers to the elastic modulus of the material, expressed in megapascals (MPA). The radial section bending moment of inertia parameter is expressed in fourth-order millimeters. The angle rebound compensation amount The unit is degrees, derived and calibrated through tensile testing combined with theoretical derivation.

[0112] Specifically, the process of retrieving the 3D contour mold part model includes: extracting a negative digital cavity 3D model that matches the geometric topological parameters of the outer surface of the target multi-step rounded finished product, and defining the negative digital cavity 3D model as the 3D contour mold part model. Specifically, the geometric generation steps of the negative digital cavity 3D model are as follows: the computer-aided manufacturing system performs spatial Boolean subtraction to establish a solid mold reference block whose volume fully encloses the target product; the 3D solid surface model of the target multi-step rounded finished product is used as the subtraction tool; the intersecting volume is subtracted from the solid mold reference block, and the resulting model with an internal 3D cavity is the 3D contour mold part model. A 3D contour solid mold is then manufactured based on this model. The 3D contour solid mold is assembled from multiple movable inserts arranged in a ring, forming a constrained cavity when closed.

[0113] Furthermore, the control of the three-dimensional contouring mold, based on the three-dimensional contouring mold part model, applies a forced closing and correction operation to all stepped areas, including: sending the rounding transition part output from the previous station onto the lower die positioning support column of the finishing and sizing station. The servo-driven pressing main slide of the press machine tool is controlled to drive the upper die module downwards, contacting and triggering the lateral slide rail and thrust drive mechanism. Specifically, the thrust drive mechanism has a built-in transmission wedge block that maps the vertical downward displacement to a horizontal radial closing displacement, with a physical transmission wedge inclination angle... The value range is specified as 10 to 20 degrees. Multiple movable carbide inserts converge towards the central axis along a preset radial trajectory, with their inner walls contacting and enveloping the rounded transition piece. Upon reaching the bottom dead center position, a lateral compressive load and a centripetal closing pressure are applied to all independent step areas, forcing the outer contour of the rounded transition piece to conform to the negative cavity surface.

[0114] Furthermore, the step of superimposing static springback values ​​during the forced closing correction operation to close and compress the corner areas corresponding to all steps, correcting roundness and closing gaps, includes: reading the pre-stored static springback values. During the correction operation, the servo control module dynamically adjusts the closed coordinates of the movable insert, causing the movable carbide insert to continue physically advancing a linear travel distance corresponding to the static springback value towards the central axis. Specifically, the linear travel distance... The geometric trigonometric conversion formula is:

[0115] ;

[0116] in, The unit is millimeters; The radial springback compensation parameter is in millimeters. The inclination angle parameter of the transmission wedge is given in degrees. The value is a tangent trigonometric function. During the advancement process, the mold applies closed compressive stress to the circumferential region, stepped transition surface, and open joint region of the rounded transition piece. After unloading the mechanical constraint force, the rounded transition piece elastically recovers outward. The elastic recovery offsets the inward compression, resulting in the output of the multi-step rounded finished product.

[0117] Step S400: Obtain the correlation parameters of adjacent step dimensions and the parameters of continuous operation batches.

[0118] In this embodiment, step S400 includes: extracting the diameter ratio and wall thickness difference of paired adjacent steps; defining the diameter ratio and wall thickness difference as adjacent step size correlation parameters; obtaining the current cumulative stroke cycle value of the forming equipment, and establishing the current cumulative stroke cycle value as a continuous operation batch parameter.

[0119] Understandably, in multi-step stamping operations, the geometric differences between adjacent steps and the physical state of the equipment evolving over time are variables in dynamic springback calculations. During the operation of the stamping die, the internal state evolves with each stroke. Correlation parameters and batch parameters are obtained to construct the input data for the computational model.

[0120] Specifically, the extraction of the diameter ratio and wall thickness difference between paired adjacent steps includes: the processor extracting the three-dimensional geometric feature information of the target multi-step rounded finished product; separating the target design parameters of the connected front and rear steps from the feature information; and calling the logic operation unit to obtain the quotient obtained by dividing the nominal outer diameter setting value of the front independent step by the nominal outer diameter setting value of the rear independent step, which is defined as the diameter ratio. Specifically, the diameter ratio... The mathematical formula for solving this problem is:

[0121] ;

[0122] in, Set a nominal value for the outer diameter of the independent front step, in millimeters; A nominal value is set for the outer diameter of the rear independent step, in millimeters; This represents a function that takes the maximum value among the parameters. This represents a function that takes the minimum value among the parameters. This is a unitless parameter. The formula uses a combination of maximum and minimum values ​​to ensure that the calculated diameter ratio is always greater than or equal to 1.0. Further, the absolute value of the physical thickness difference obtained by subtracting the average measured actual formed wall thickness of the front independent step from the average measured actual formed wall thickness of the rear independent step is defined as the wall thickness difference. Specifically, the wall thickness difference... The algebraic solution formula is:

[0123] ;

[0124] in, The unit is millimeters; The average measured value of the actual formed wall thickness of the front independent step is in millimeters. The average measured value of the actual formed wall thickness of the rear independent step is in millimeters.

[0125] Furthermore, defining the diameter ratio and wall thickness difference as adjacent step size association parameters includes: the system allocating an address space in memory. Specifically, the operation process is as follows: a contiguous 64-bit physical address space is allocated in the high-speed flash memory inside the main control system; the diameter ratio is written in the lower 32-bit address segment using the IEEE 754 single-precision floating-point standard, and the wall thickness difference is written in the higher 32-bit address segment using the same standard; the two are combined and packaged to form the adjacent step size association parameters in a joint data structure format.

[0126] Next, obtaining the current cumulative stroke cycle value of the forming equipment and establishing it as a continuous operation batch parameter includes: configuring an incremental photoelectric rotary encoder on the output rotating shaft of the forming equipment. When the forming equipment performs a pressing action, the encoder outputs a pulse sequence signal. The accumulator register inside the counter module performs incremental step addition operations. Specifically, the strict hardware logic judgment condition for triggering the incremental step addition operation is: the quadrature pulse count value output by the photoelectric rotary encoder reaches the single-turn physical resolution calibration constant within a single increment cycle, and the system interrupt interface synchronously receives the Z-phase zero-position transition level signal corresponding to the highest mechanical dead point. When the above two conditions are true, it is determined that a complete mechanical pressing cycle action has been completed, and the accumulator register performs an integer increment operation. The integer value recorded in the accumulator register is defined as the current cumulative stroke cycle value. The system establishes the current cumulative stroke cycle value as the continuous operation batch parameter.

[0127] Step S500: Establish the stress coupling coefficient based on the adjacent step size correlation parameters.

[0128] In this embodiment, step S500 includes: evaluating the lateral transmission intensity of residual shear stress generated during the multi-step composite encirclement process using the adjacent step size correlation parameters; constructing a nonlinear mapping rule based on the lateral transmission intensity of residual shear stress; and calculating the stress coupling coefficient characterizing the degree of mutual interference between steps through the nonlinear mapping rule.

[0129] Specifically, the method of evaluating the lateral transmission strength of residual shear stress generated during the multi-step composite encirclement process using the correlation parameters of adjacent step dimensions includes: system call to the stored stress evaluation function logic module. Substituting the diameter ratio and the wall thickness difference into the mechanical equations, a unitless floating-point value characterizing the physical efficiency and interaction strength of interlayer residual stress transmission is calculated. Specifically, the empirical mathematical model equation for solving the unitless floating-point value by the stress evaluation function logic module is as follows:

[0130] ;

[0131] in, This refers to the lateral transmission strength parameter of the residual shear stress, which has no unit. The shear conduction constant between material layers is dimensionless and ranges from 0.85 to 1.15. The diameter ratio parameter is unitless. The wall thickness difference parameter is in millimeters. The average wall thickness measured in a pair of adjacent steps is the smaller value, expressed in millimeters. For the natural constant An exponential function with base π. This relates to the interlaminar shear physical conduction constant. The system calls the nominal Poisson ratio parameter from the material library. Through formula Perform automated assignment (overqualified field truncation).

[0132] Furthermore, the construction of the nonlinear mapping rule based on the lateral transmission intensity of residual shear stress includes: generating a mathematical response function curve in the memory area of ​​the control system based on discrete test data. The system then establishes the conversion processing logic based on the mathematical response function curve as the nonlinear mapping rule. Specifically, the equation of the univariate quadratic polynomial response function curve constructed by the nonlinear mapping rule is:

[0133] ;

[0134] in, The springback interference magnification parameter is used as the output variable on the vertical axis and has no unit. The residual shear stress transverse transmission strength parameter, which is used as the input variable on the horizontal axis, is dimensionless; 1.0 is a dimensionless bias constant. The coefficient of the first-order constant term is dimensionless and ranges from 0.05 to 0.20. This is the coefficient of the second-order constant term, dimensionless, and ranging from 0.01 to 0.05. and The establishment process includes: systematically extracting the ratio of the yield strength to the nominal tensile strength of the processed metal (defined as the yield ratio). ), execute nonlinear correlation formula and (when Automatic interpolation calculation is performed when the value is in the range of 0.5 to 0.9 (boundary locking is triggered when the value exceeds the limit), thereby enhancing the mechanical interpretability and reliability of the prediction model.

[0135] Next, the calculation of the stress coupling coefficient characterizing the degree of interference between steps using nonlinear mapping rules includes: the microprocessor inputting the calculated lateral transmission intensity of the residual shear stress into the calculation core subroutine. The calculation core subroutine outputs the final value of the springback interference amplification factor based on the function equation. The final value of the springback interference amplification factor is defined as the stress coupling coefficient. Specifically, before its establishment, the control logic adjusts the output springback interference amplification factor. The procedure applies numerical boundary constraints: it determines the boundary conditions using Boolean comparison expressions, and if the calculation result... Then, the assignment correction will be performed. If the calculation result Then, the assignment correction will be performed. ; and will be in the security domain The parameter is defined as the stress coupling coefficient.

[0136] Step S600: Generate a compensation attenuation factor based on the continuous operation batch parameters.

[0137] In this embodiment, step S600 includes: extracting the estimated values ​​of mold thermal accumulation and mechanical wear corresponding to the parameters of the continuous operation batch; substituting the estimated values ​​of mold thermal accumulation and mechanical wear into a preset life decay model; and using the preset life decay model to output a compensation decay factor to offset the accumulation of dynamic errors.

[0138] Understandably, during operation, the friction between the mold and the metal surface converts into heat energy. The thermal expansion and contraction of the mold cavity surface reduces the absolute coordinates of the closed cavity. Simultaneously, strip friction causes microscopic abrasive wear on the mold's working surface, leading to outward retraction of the cavity surface and an increase in cavity size. The combined effect of these two factors results in dynamic dimensional drift in the machining system.

[0139] Specifically, the extraction of the estimated values ​​of mold thermal accumulation and mechanical wear corresponding to the parameters of continuous operation batches includes: the control system calling the heat conduction temperature rise model; calculating the estimated physical displacement of the inner wall of the cavity due to thermal expansion inward; and defining the estimated physical displacement as the estimated value of mold thermal accumulation. Specifically, the equivalent body temperature increment estimate output by the three-dimensional temperature rise calculation model based on Fourier's law of heat conduction. The formula is:

[0140] ;

[0141] in, The unit is Celsius (°C) ); The physical heating constant for a single stamping operation is given, and the unit is joules (J). ); The parameters for the continuous operation batch are unitless. This refers to the specific heat capacity of mold steel, expressed in joules per kilogram per degree Celsius. ); The effective heat-receiving mass of the mold, expressed in kilograms (kg). ); This is the convective heat dissipation constant, expressed as the reciprocal of a second. ); The total physical time of operation is expressed in seconds. Based on this, the estimated value of mold heat accumulation is... The displacement transformation formula is:

[0142] ;

[0143] in, The unit is millimeters; The coefficient of linear thermal expansion of the mold material, expressed as the reciprocal of the value in degrees Celsius. ); The effective cavity thickness is expressed in millimeters.

[0144] Simultaneously, the wear condition assessment module is invoked. The average radial depth of volumetric material loss on the die surface under the current cumulative number of stamping operations is calculated, and this average radial depth of volumetric material loss is defined as the estimated mechanical wear value. Specifically, the estimated mechanical wear value is calculated based on Archard's wear theory. The equation is:

[0145] ;

[0146] in, The unit is millimeters; It is a dimensionless wear coefficient constant, with a value of [value missing]. to ; This is the calibration value of the contact normal pressure on the mold surface, in megapascals (MPa). ); The parameters represent the relative sliding friction displacement during a single stamping operation, in millimeters. The parameters for the continuous operation batch are unitless. This refers to the Brinell hardness parameter of the mold, in megapascals (MPa). Wear coefficient. The establishment of this parameter is based on the root mean square parameter of the internal cavity roughness periodically fed back by the central coordinate measuring machine. (Unit: micrometer) Calling a linear algorithm Derivation and generation.

[0147] Furthermore, the step of substituting the estimated values ​​of mold thermal accumulation and mechanical wear into the preset life decay model includes: the system feeding the positive parameter representing the estimated value of mold thermal accumulation and the negative parameter representing the estimated value of mechanical wear into the superposition calculation unit within the preset life decay model. This calculates the actual net displacement of the combined boundary physical drift of the mold cavity under the current continuous operation batch parameters. Specifically, the flow formula for the algebraic summation calculation performed by the vector addition superposition calculation unit is:

[0148] ;

[0149] in, The net displacement of the physical drift at the comprehensive boundary is expressed in millimeters. The formula defines the estimated value of the mold's thermal accumulation, representing inward expansion, as a positive parameter, and the estimated value of the mechanical wear, representing outward retreat, as a negative parameter, and then algebraically adds them together to obtain the result. .

[0150] Next, the step of using a preset lifetime decay model to output a compensation decay factor to offset the accumulation of dynamic errors includes: the system performing a proportional scaling on the displacement. The generated floating-point multiplier scaling factor is defined as the compensation decay factor. Specifically, the compensation decay factor is generated. The dynamic adjustment formula is:

[0151] ;

[0152] in, The compensation attenuation factor is unitless. This is a unitless parameter; The net displacement of the physical drift at the comprehensive boundary is expressed in millimeters. The reference radial rebound constant parameter is extracted from the step at room temperature, in millimeters.

[0153] Step S700: The stress coupling coefficient, the compensation attenuation factor, and the static rebound value are fused and calculated to generate a target rebound compensation command.

[0154] In this embodiment, as Figure 5As shown, step S700 includes: multiplying the static rebound value with the stress coupling coefficient to obtain a primary compensation parameter; determining an interception before performing a correction and reduction operation on the primary compensation parameter combined with the compensation attenuation factor; performing a correction and reduction operation on the primary compensation parameter combined with the compensation attenuation factor to obtain a target compensation offset; and encapsulating the target compensation offset into a data stream to generate a target rebound compensation command.

[0155] Specifically, the step of multiplying the static springback value with the stress coupling coefficient to obtain the primary compensation parameter includes: the processor extracting the static springback value; synchronously sending the static springback value and the stress coupling coefficient to the calculator unit; the system storing the product result in a first-level internal fast calculation register and explicitly defining the product result as the primary compensation parameter. Specifically, obtaining the primary compensation parameter... The expression for algebraic multiplication is established as follows:

[0156] ;

[0157] in, The primary compensation parameter is in millimeters. The radial compensation component data is extracted from the static rebound value, in millimeters; The stress coupling coefficient is substituted in; it has no unit.

[0158] Furthermore, before performing the correction and reduction operation by combining the primary compensation parameters with the compensation attenuation factor, the system defines a set limit value as the preset material forming limit safety threshold. Specifically, the preset material forming limit safety threshold... The formula for assessing physical interventions is:

[0159] ;

[0160] in, The unit is millimeters; The nominal outer radius of the current step is expressed in millimeters. The ultimate failure true strain parameter is obtained by physical conversion based on the gauge length elongation after fracture in the standard tensile test of metals, and has no unit. The safety reduction factor is dimensionless and has a fixed value of 0.85 at the system's underlying level. This formula prevents the arithmetic unit from outputting position command parameters that exceed the critical point for macroscopic fracture of the metallic material. The processor determines whether the primary compensation parameter exceeds a preset material forming limit safety threshold. If the primary compensation parameter is greater than the preset material forming limit safety threshold, the control system performs a data physical truncation operation, directly writing the parameter represented by the preset material forming limit safety threshold into a designated address in a register, replacing the primary compensation parameter. The system log also records the timestamp of the event and the parameter before replacement.

[0161] Next, the step of combining the primary compensation parameters with the compensation attenuation factor to perform a correction and reduction operation to obtain the target compensation offset includes: the processor performing an algebraic correction operation on the secure primary compensation parameters and the compensation attenuation factor. The output correction value is established as the target compensation offset. Specifically, obtaining the target compensation offset... The terminal algebra correction formula is:

[0162] ;

[0163] in, The target compensation offset value is expressed in millimeters. The primary compensation parameters, measured in millimeters, are used to determine whether they are within the safety limits. The compensation attenuation factor parameter is the final fused parameter and has no unit.

[0164] Furthermore, the step of encapsulating the target compensation offset into the control protocol data stream to generate the target bounce compensation instruction includes: a system call protocol stack mapping module. A complete serialized data frame block, encapsulated and processed by the Industrial Ethernet message protocol standard, is defined as the target bounce compensation instruction. Specifically, the Industrial Ethernet fieldbus communication protocol stack data frame block is fixedly generated as a 64-bit data string structure: bits 0 to 7 are encapsulated... The hexadecimal frame start identifier; bits 8 to 15 encapsulate the target slave's physical network address; bits 16 to 23 encapsulate the read / write operation control code; bits 24 to 47 constitute the data payload area, where the first 12 bits are written in binary code as the unsigned value converted from the target compensation offset, and the last 12 bits are written as the pressure adjustment data; bits 48 to 63 are written based on... Standard generated cyclic redundancy check signature.

[0165] Step S800: Control the compensation and shaping actions of finishing and sizing processes and corner shaping operations in subsequent batches according to the target springback compensation command.

[0166] In this embodiment, as Figure 6As shown, step S800 includes: parsing the position offset data and pressure adjustment data carried by the target springback compensation command; sending the position offset data to the position control terminal to guide the dynamic adjustment of the mold closing depth; and sending the pressure adjustment data to the pressure control terminal to realize the dynamic application of the closing gap docking pressure.

[0167] Specifically, the parsing of the target rebound compensation command carrying position offset data and pressure adjustment data includes: the underlying communication protocol decoding firmware program, based on a pre-compiled bit address mapping offset mask register table, dividing and parsing the data payload segment into two independent numerical variable control information blocks. Specifically, the bit address mapping offset mask extraction rule is defined as: using a fixed hexadecimal mask. Perform a bitwise AND operation on the data payload area, then logically shift right by 12 bits to extract the first 12 bits of data and convert them into values ​​in micrometers, establishing this as the position offset data; use a hexadecimal fixed mask. Perform a bitwise AND logic calculation to directly extract the last 12 bits of data and convert them into unsigned integers for the pressure adjustment data.

[0168] Furthermore, the step of sending the position offset data to the position control terminal to guide the dynamic adjustment of the mold closing depth includes: the processor of the position control terminal performing an accumulation calculation with the received position offset data and the machine tool's theoretical absolute coordinate reference to generate the target extreme value bottom dead center absolute pulse coordinates, which include spatiotemporal dynamic compensation physical margins. Specifically, the target extreme value bottom dead center absolute pulse coordinates... The hardware execution formula for the accumulation instruction is:

[0169] ;

[0170] in, The unit is the number of pulses; The theoretical bottom dead center absolute space reference pulse parameters for the machine tool axis zero point, pre-calibrated, in units of pulse count; The target compensation offset parameter is a micrometer-level value after unit conversion, i.e. The unit is micrometer ( ); The pulse equivalent conversion proportional constant for the AC servo drive closed-loop system is assigned a value of 100 pulses per micrometer. During the pressing action, the position comparator scans the actual coordinate feedback value, and when it matches the stated value... When a match is found, stop and reverse signals are sent to the drive motor.

[0171] Next, the step of sending the pressure adjustment data to the pressure control terminal to dynamically apply the closing gap connection pressure includes: the pressure control terminal converting the pressure adjustment data into an analog control voltage signal, dynamically setting and steplessly adjusting the back pressure overflow throttling resistance limit on the hydraulic return oil line of the hydraulic buffer lifting cylinder. Specifically, the digital-to-analog converter core board maps the extracted pressure adjustment data into a 0 to 10 volt DC analog control reference voltage signal via a 12-bit resolution DAC channel. The electro-hydraulic proportional overflow control valve is used to adjust the back pressure overflow throttling resistance limit. The physical mapping model formula is:

[0172] ;

[0173] in, The unit is megapascal; The foundation rigidity maintenance pressure constant for the hydraulic system calibration, in megapascals; This is the physical conversion constant of pressure to voltage in a proportional valve, with units of megapascals per volt (MPa). ); The unit is volt (Volt) Based on dynamic settings. It outputs a set reverse resistance pressure to the extrusion area, causing the material structure to undergo plastic deformation and interlock, thus eliminating the gap between the joints.

[0174] By controlling the contraction action of the position control terminal and the pressure holding action of the pressure control terminal, the forming equipment eliminates multi-step interference and equipment degradation bias, and realizes closed-loop control of stress compensation.

[0175] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for calculating springback compensation and forming of multi-step composite stamping features, comprising the following steps: The strip to be stamped is pre-bent to form a multi-step pre-bent blank. Perform a step-by-step rolling operation on the multi-step pre-bent blank to generate a rounded transition part; Based on the static springback value, the rounded transition piece is subjected to finishing and sizing processes as well as corner shaping operations to generate a multi-step rounded finished product. Its features are, The method also includes a dynamic compensation control step: Obtain the correlation parameters between adjacent step dimensions and the parameters of continuous operation batches; The stress coupling coefficient is established based on the correlation parameters of the adjacent step dimensions; A compensation attenuation factor is generated based on the continuous operation batch parameters; The stress coupling coefficient, the compensation attenuation factor, and the static rebound value are fused together to generate a target rebound compensation command; The compensation and shaping actions of the finishing and sizing process and the corner shaping operation in subsequent batches are controlled according to the target springback compensation command.

2. The springback compensation calculation and forming method for multi-step composite stamping features according to claim 1, characterized in that, The process of pre-bending the strip to be stamped to generate a multi-step pre-bent blank includes: The raw material is precisely cut to suppress micro-cracks at the material edges, and the strip to be stamped is obtained. Calculate the unfolded dimension parameters corresponding to each independent step in the strip to be stamped; The strip to be stamped is subjected to segmented bending operation according to the unfolded size parameters to generate the multi-step pre-bent blank in an unfolded state.

3. The springback compensation calculation and forming method for multi-step composite stamping features according to claim 1, characterized in that, The step-by-step rolling operation on the multi-step pre-bent blank to generate a rounded transition part includes: The multi-step pre-bending blank is divided into multiple forming stress nodes; Rolling forming force is applied to the multiple forming force nodes in a set sequence. Set the position of the rounded joint generated in the previous rounding step as the forming starting point of the subsequent rounding step. By applying the rolling forming force multiple times to disperse the deformation stress of the material, the risk of cracking of the part caused by excessive local sudden stress is reduced, thus generating the round transition part.

4. The springback compensation calculation and forming method for multi-step composite stamping features according to claim 1, characterized in that, The step of performing finishing and sizing processes and corner shaping operations on the rounded transition piece based on static springback values ​​to generate a multi-step rounded finished product includes: Retrieve the 3D contour mold part model; The three-dimensional contour mold is controlled to apply a forced clamping correction operation to all step areas based on the three-dimensional contour mold part model; In the forced closing correction operation, the static rebound value is superimposed to close and compress the corner areas corresponding to all steps, mechanically correct the roundness and closing gap, and obtain the multi-step rounded finished product that has reached the target closed state.

5. The springback compensation calculation and forming method for multi-step composite stamping features according to claim 1, characterized in that, The process of obtaining the correlation parameters of adjacent step dimensions and the parameters of continuous operation batches includes: Extract the diameter ratio and wall thickness difference of the pairs of adjacent steps; The diameter ratio and the wall thickness difference are defined as the adjacent step size correlation parameters; Obtain the current cumulative stroke cycle value of the forming equipment, and establish the current cumulative stroke cycle value as the continuous operation batch parameter.

6. The springback compensation calculation and forming method for multi-step composite stamping features according to claim 1, characterized in that, The stress coupling coefficient established based on the adjacent step size correlation parameters includes: The lateral transmission strength of residual shear stress generated during the multi-step composite encirclement process is evaluated using the correlation parameters of adjacent step dimensions. A nonlinear mapping rule is constructed based on the lateral transmission intensity of the residual shear stress; The stress coupling coefficient, which characterizes the degree of mutual interference between steps, is calculated using the nonlinear mapping rule.

7. The springback compensation calculation and forming method for multi-step composite stamping features according to claim 1, characterized in that, The step of generating the compensation attenuation factor based on the continuous operation batch parameters includes: Extract the estimated values ​​of mold heat accumulation and mechanical wear corresponding to the parameters of the continuous operation batch; Substitute the estimated values ​​of mold thermal accumulation and mechanical wear into the preset life decay model; The preset lifetime decay model is used to output the compensation decay factor to offset the accumulation of dynamic errors.

8. The springback compensation calculation and forming method for multi-step composite stamping features according to claim 1, characterized in that, The step of fusing the stress coupling coefficient, the compensation attenuation factor, and the static rebound value to generate the target rebound compensation command includes: The static rebound value is multiplied by the stress coupling coefficient to obtain the primary compensation parameters; The primary compensation parameters are combined with the compensation attenuation factor to perform a correction and reduction operation to obtain the target compensation offset. The target compensation offset is encapsulated into the control protocol data stream to generate the target rebound compensation command.

9. The springback compensation calculation and forming method for multi-step composite stamping features according to claim 8, characterized in that, Before performing a correction and reduction operation by combining the primary compensation parameters with the compensation attenuation factor to obtain the target compensation offset, the following steps are included: Determine whether the primary compensation parameter exceeds the preset material forming limit safety threshold; If the primary compensation parameter exceeds the preset material forming limit safety threshold, the primary compensation parameter will be truncated to the preset material forming limit safety threshold, and an over-limit warning action will be triggered.

10. The springback compensation calculation and forming method for multi-step composite stamping features according to claim 1, characterized in that, The compensation shaping action, which controls the finishing and sizing process and corner shaping operation in subsequent batches according to the target springback compensation command, includes: Analyze the position offset data and pressure adjustment data carried by the target rebound compensation command; The position offset data is sent to the position control terminal to guide the dynamic adjustment of the mold closing depth; The pressure adjustment data is sent to the pressure control terminal to realize the dynamic application of the pressure for closing the gap.

Images