Electrical steel winding method for winding tension profile control and edge crack suppression

Abstract

The invention relates to an electrical steel winding method for winding tension profile control and edge crack suppression, which comprises the following steps of: at the initial winding stage, loading tension by adopting a tension response initial displacement method according to the previous process state of an electrical steel strip, so that a tension establishment path is coordinated with a residual stress release trend, and an edge buffer state is formed; in the middle winding section, an edge drift tolerance area of a tension section is constructed, and unsteady-state elastic tolerance is set through tension fluctuation of a + / -10 mm area on the edge of the steel belt, so that the edge has limited micro-expansion capacity to release local stress concentration; in the whole winding process, controllable disturbance is allowed to happen to the edge of the steel belt, a disturbance collapse area is set, and micro-slippage and local tension disturbance are attenuated and dissipated on the edge through structural path adjustment of an edge area; and at the winding tail end, a section tension compression closing mechanism is adopted, tension difference in the edge is converged, and a tension closing belt is constructed at the edge, so that the edge crack risk caused by critical tension disturbance when the winding diameter is reduced is restrained.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrical steel winding method, in particular to an electrical steel winding method for winding tension profile control and edge crack suppression. BACKGROUND

[0002] In the current electrical steel winding method for winding tension profile control and edge crack suppression, such as the cold-rolled strip winding tension control method described in patent CN116673344A, although a relatively systematic three-stage tension segmentation strategy is proposed in terms of winding tension control, and corresponding specific tension values and additional tension coefficients can be set according to steel strength, thickness, width and other parameters to improve the problem of single and non-adjustable tension in traditional methods, there are still several key deficiencies and limitations, which are difficult to fully meet the technical requirements of edge crack suppression and fine tension profile regulation in the winding process of high-end electrical steel. Firstly, this method only adjusts from the perspective of overall tension control, lacks a deep control mechanism for the transverse tension distribution, i.e., the tension profile, and cannot identify and respond to the difference in stress state between the edge and the center of the winding material during the winding process in real time. High-magnetic-property materials such as electrical steel are extremely sensitive to edge strain, and edge cracks are easily induced by sudden changes in edge tension, especially when the winding diameter increases and the material rebound increases, making it more difficult to control such edge cracks.

[0003] Secondly, the existing method mainly relies on controlling the winding specific tension, additional tension, and transition rate of the tension stabilization zone to achieve overall tension stabilization. Its control logic is too macroscopic and mainly focuses on axial tension changes, ignoring the dynamic evolution process of local plastic fatigue accumulation and early crack initiation window period at the edge of the coil. Therefore, it lacks a systematic deployment of edge stress release and edge crack compression closure mechanisms, and does not have the ability to actively intervene in the winding tension profile to close the crack source before the edge crack initiates. Thirdly, the tension transition control in this method mainly uses a linear tension decline method based on the winding height as the criterion, lacks tension gradient closed-loop feedback and real-time stress field modeling support, and is prone to control lag or tension mismatch. In the winding process of high-strength steel or ultra-thin electrical steel, it is easy to form internal loose coils and external scratches due to untimely or excessive tension decline. Fourthly, the technology described in the patent does not combine temperature control means to adjust the plastic state of the edge. In practical winding applications of electrical steel, the plasticity of the edge has a decisive influence on the deformation capacity of the steel in the tension peak area. If the ductility of the edge region is not enhanced by heating, it is difficult to avoid crack initiation during tension peak loading. Therefore, the lack of temperature control measures makes it impossible to move the process window forward in the tension convergence area.

[0004] This method lacks the prediction of tension convergence time constant and the construction of dynamic triggering logic, and lacks a predictive management mechanism for edge stress fields. Therefore, it cannot achieve early or delayed triggering of edge locking actions based on regional stress response. Consequently, in complex winding rhythms, edge state adjustment remains passively lagging, failing to accurately capture and intervene in crack initiation. Sixth, during the formation of the coiled structure, this scheme uses a homogeneous tension advancement method for convolution, ignoring the edge-to-center tension compression closure logic. That is, it fails to establish a time-division and zone-division tension closure path, thus failing to prioritize early edge closure to a stable state. After the core is completed, the tension recoil from the core causes edge tension redistribution, leading to repeated crack opening and closing, resulting in macroscopic cracking or even severe defects such as edge layer peeling. Furthermore, although this method considers the influence of strength and thickness factors of different steel grades on tension, its tension setting is still based on a fixed empirical table rather than an adaptive control model, making it difficult to adapt to the dynamic winding requirements of multiple working conditions in real time. Summary of the Invention

[0005] The purpose of this invention is to provide a method for winding electrical steel with controlled winding tension profile and suppressed edge cracks, thereby solving some of the drawbacks and shortcomings pointed out in the background art.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a method for controlling the winding tension profile and suppressing edge cracks in electrical steel winding, comprising: in the initial stage of winding, according to the previous process state of the electrical steel strip, applying tension using the tension response initial displacement method, so that the tension establishment path and the residual stress release trend are coordinated to form an edge buffer state; in the middle section of winding, constructing an edge drift tolerance zone of the tension profile, and setting an unsteady elastic tolerance for tension fluctuations in the ±10 mm area of ​​the steel strip edge, so that the edge has limited micro-expansion and contraction capabilities to release local stress concentration; Throughout the winding process, controllable disturbances are allowed at the edge of the steel strip, and a disturbance trapping zone is set. By adjusting the structural path of the edge region, micro-slippage and local tension disturbances are attenuated and dissipated at the edge. At the winding end, a cross-sectional tension compression closure mechanism is adopted. By converging the tension difference between the edges and the center, a tension closure band is constructed at the edge to suppress the risk of edge cracking caused by critical tension disturbance when the roll diameter shrinks.

[0007] Furthermore, in the tension response initial displacement method, the initial tension loading rate is 0.2-0.6 times that of the conventional rate, and the residual stress at the edge is gradually released through micro-amplitude alternating tightening and loosening operations during the loading process; in the initial stage, the edge is laterally guided by a preset micro-amplitude auxiliary roller to form a nonlinear buffer zone for tension establishment.

[0008] Furthermore, the threshold for adjusting the initial tension increase based on the grain orientation distribution of the steel strip in the initial stage is used to synchronize the residual stress release process with the winding tension establishment process; the width of the edge drift tolerance zone is adjusted to ±5 to ±15 mm based on the steel strip thickness, and the tolerance zone width is dynamically corrected when the thickness fluctuation exceeds the set value.

[0009] Furthermore, during the entire winding process, the position of the disturbance and sinking area is corrected by the difference in the transverse tension of the steel strip, so that it always corresponds to the high-risk area of ​​edge cracks; the profile tension compression closure mechanism adopts a step-by-step convergence strategy at the end of the winding stage, first reducing the edge tension, then increasing the center tension, and finally converging to the mean value.

[0010] Furthermore, by adjusting the diameter ratio and contact angle of the take-up roller at the winding end, the formation speed of the cross-sectional tension compression closure zone is increased to shorten the window period for edge crack initiation; the tension compression closure mechanism is combined with edge zone temperature control measures, which enhance the edge plasticity by slightly raising the temperature before tension convergence.

[0011] Furthermore, during the winding diameter ratio adjustment process, the edges are first gradually reduced at a low speed, then the center is gradually reduced at a high speed, and finally both sides converge synchronously to form a gradient winding diameter closure method with a time difference to shorten the edge tear window period; at the winding end, the winding diameter ratio adjustment adopts the method of dividing the winding length into three segments, each segment having a different winding diameter ratio decay rate, with the edge area rate always leading the middle area, to form a protective zone that closes in advance.

[0012] Furthermore, the contact angle adjustment involves continuously scanning the take-up roller angle at the winding end in small amplitudes, so that the edge of the tension profile gradually converges under multiple micro-angle states, reducing stress concentration at a single angle; in the contact angle adjustment, it is first adjusted to be 2–5° larger than the target angle, and then reversed back to the target angle to generate edge plastic micro-flow and eliminate stress peaks in advance.

[0013] Furthermore, during the contact angle adjustment process, a dynamic step table for angle is calculated in real time according to the roll diameter, and the angle adjustment rate is switched at each roll diameter threshold to maintain the angle change gradient throughout the tension compression closure process; the dynamic step table for angle is a graded control table that pre-sets the contact angle and corresponding adjustment rate according to different roll diameter thresholds, and is used to switch the contact angle adjustment rate when the roll diameter changes to maintain the angle change gradient during the tension compression closure process. During the contact angle adjustment process at the end of winding, based on the real-time change of the coil diameter D, an angle dynamic step function table containing multiple angle-rate coupling relationships is constructed to adaptively control the contact angle adjustment rate, so that the tension profile maintains the continuity of angle change and the stability of stress migration during the compression and closure process. The dynamic step table of angles is established based on a function.

[0014] in: The winding contact angle adjustment rate is a function of the winding diameter D; D is the current winding diameter. This is the maximum contact angle rate limit coefficient, used to limit the range of adjustment rate; The angle adjustment hysteresis attenuation coefficient controls the response sensitivity of the function in the initial stage; This is the periodic disturbance adjustment coefficient, used to simulate the disturbance component of edge tension fluctuation during angle adjustment; It is a nonlinear roll diameter response index, used to reflect the nonlinear effect of roll diameter changes on the rate at different stages; This is a constructed disturbance attenuation function used to simulate disturbance absorption and amplification behavior in different roll diameters.

[0015] Furthermore, the temperature control heating process is carried out in stages according to the stress distribution of the edge micro-regions. First, the high-stress micro-regions are locally heated, and then the temperature is extended to the low-stress micro-regions. The tension convergence time constant is calculated in advance between the edge heating and the tension convergence, and the plastic state is obtained by delaying or advancing the temperature control trigger.

[0016] Furthermore, after the temperature control is completed, the edge is cooled for a short time to harden the surface layer and keep the inner layer plastic, so as to form a double-layer edge structure; the tension compression closure process adopts the sequence of closing the edge first and then the center closing later, first completing the small-range tension closure at the edge, and then completing the full-width closure in the middle, so that the edge is locked in a stress state first.

[0017] The beneficial effects of this invention are as follows: By refining the design of multiple key stages throughout the winding process, including tension establishment path, edge stress release, local disturbance tolerance, and end tension compression closure, the stress adaptability and fracture suppression capability of the steel strip edge during winding are significantly improved. Unlike traditional constant tension or overall control methods, this invention introduces a tension response initial displacement method and an edge drift tolerance zone, preventing instantaneous stress impacts during the tension establishment stage and enabling the edge to have micro-expansion and contraction capabilities, thus suppressing crack initiation from the source.

[0018] Furthermore, at the end of the winding process, this invention employs a profile tension compression closure mechanism combined with a coordinated adjustment strategy of the winding diameter ratio and contact angle. By introducing step-by-step convergence and a dynamic angle step table, rapid compression and continuous convergence of the tension profile are achieved. Simultaneously, an edge heating-cooling control logic based on micro-region stress distribution is introduced, enabling directional plastic strengthening of the edge material before closure, constructing a double-layer structure for stress guidance and crack shielding. This synergistic mechanism of thermo-mechanical coupling and gradual control significantly shortens the crack initiation window period, improves the stability and edge yield of high-strength electrical steel under high-speed winding conditions, and has significant engineering application value and promising prospects for widespread application. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the tension profile control and edge crack suppression of electrical steel winding according to the present invention.

[0020] Figure 2 This is a diagram showing the relationship between the flexible tension of the electrical steel winding and the intelligent profile control function of the present invention.

[0021] Figure 3 This is a flowchart of the three-stage diameter and angle control process at the end of the electrical steel winding of the present invention.

[0022] Figure 4 This is a cross-sectional view of the intelligent tension of non-oriented silicon steel winding and an edge crack suppression diagram in Embodiment 1 of the present invention.

[0023] Figure 5 This is a schematic diagram of the dynamic adjustment of the three sections of the electrical steel winding end diameter and contact angle, and the graded temperature control closure, as shown in Embodiment 2 of the present invention. Detailed Implementation

[0024] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0025] Combined with appendix Figure 1This invention relates to a method for controlling the winding tension profile and suppressing edge cracks in electrical steel winding. In the initial winding stage, based on the residual stress distribution resulting from heat treatment, straightening, leveling, pickling, and their combinations in the preceding processes, the stress sensitivity of the steel strip's edge region is pre-identified, and tension loading is applied using a tension response initiation displacement method. The initiation displacement method involves controlling the winding force to exhibit a non-linear, gradual increase path when the steel strip initially enters the winding system, and configuring micro-displacement intervention units in the edge region to form a dynamic stress buffer during the tension build-up process. This control strategy aims to coordinate the tension build-up path with the original residual stress release trend of the electrical steel strip, thereby avoiding the instantaneous crack initiation caused by the superposition of tension and residual stress, and achieving a gradual balance of the edge state, forming an edge buffer state with good plastic response. Subsequently, in the middle winding stage, an edge drift tolerance zone of the tension profile is constructed in the transverse width direction of the steel strip. This tolerance zone is located within ±10 mm inside the strip edge, and by setting an unsteady elastic tolerance for local tension fluctuations, the tension in this area can be periodically disturbed within a certain range without triggering concentrated stress transmission. This non-steady-state elastic tolerance setting, by adjusting the edge zone feedback gain coefficient, tension response delay time, and micro-displacement compensation amplitude in the winding tension control system, enables the steel strip edge to possess limited micro-expansion capability. The introduction of edge micro-expansion capability can alleviate the stress concentration trend caused by slight fluctuations in steel strip thickness, uneven edge guidance, or local deformation, promoting stress transfer or dissipation within the edge region.

[0026] During the winding process, due to factors such as guidance, tension fluctuations, steel strip edge defects, thickness non-uniformity, and differences in edge microstructure, the steel strip edge often inevitably exhibits unstable behaviors such as micro-slippage, local undulations, and tension disturbances. Traditional tension control systems usually adopt a forced steady-state control method to eliminate these disturbances, but this may instead cause the disturbances to spread to the center region of the steel strip, leading to problems such as central strip shape imbalance, poor tension reconstruction, and edge crack stress accumulation. Therefore, instead of the traditional strategy of suppressing disturbances, a three-stage disturbance management mechanism of guidance, containment, and dissipation is adopted. This allows for disturbances with limited amplitude and controllable frequency at the edge of the steel strip under set conditions, including lateral micro-slippage, longitudinal micro-stretching fluctuations, and surface floating disturbances. Subsequently, a disturbance trapping zone is set in the edge region of the steel strip. This trapping zone is achieved through edge structural path adjustment. The specific construction methods include, but are not limited to, flexible distribution of edge tension profile, local variation of elastic modulus of edge material, and contact compliance design of edge guide rollers. Through the coupling of the above structural paths, the disturbance undergoes energy transfer and gradient attenuation when it reaches the trapping zone. It is dissipated rather than reflected within the trapping zone, thereby preventing the disturbance from spreading to the middle of the steel strip or other areas. The disturbance trap region has adaptive convergence characteristics. When the disturbance amplitude is small, it only decays at the edge. However, when the disturbance amplitude exceeds the set threshold, the trap region response mechanism is activated, which guides the edge tension micro-disturbance to a dissipable path to complete rapid unloading. At the same time, the residual tension in the trap region is dynamically corrected through a micro-displacement tension compensation device to maintain the balance of the overall tension field.

[0027] At the winding end, as the coil diameter continues to decrease, the linear tension per unit length of the steel strip changes rapidly. Combined with factors such as slight thickness differences, accumulated residual stress, and multiple tension fluctuations in the edge region, the edge region becomes the most stress-sensitive area, highly susceptible to sudden edge cracking at the winding end. To address this issue, a profile tension compression closure mechanism is introduced. By controlling the convergence path of the tension difference between the edge and center, the tension profile is gradually compressed from a non-uniform distribution to a uniform closed state, thereby establishing a tension closure band with stress-resisting capabilities at the edge. The control system monitors the changing trends of edge and center tension in real time during winding, identifying deviation areas in the tension profile. Then, based on the coil diameter change, a pre-compression target curve is set, actively adjusting the rate of decrease in edge tension and the rate of increase in center tension to achieve synchronous convergence at the winding end region, completing the profile compression closure action. The compression closure process can be divided into three stages: edge pre-drop, middle strip reinforcement, and full-width balancing. In the edge pre-drop stage, some redundant stress in the boundary area is released first. Then, the middle strip gradually increases its tension to achieve a transition to the average tension of the entire winding process. Finally, by dynamically and synchronously adjusting the tension on both sides, a stable closure across the entire profile is achieved, avoiding localized tension jumps. The tension closure band forms a mechanical buffer zone between the edge and the center, providing a flexible unloading platform when the stress at the end of the steel strip no longer continues to be transmitted, absorbing end disturbances, and preventing crack initiation and propagation at the edge through stable tension transition characteristics. Furthermore, when used in conjunction with an edge area temperature control device, this tension closure band can further enhance the crack resistance of the edge material in a plastic state, thus forming a dual-protective edge crack suppression barrier before final winding.

[0028] Combined with appendix Figure 2The tension response initial displacement method differs from the traditional linear constant tension loading method. The initial tension loading rate is set between 20% and 60% of the conventional tension rise rate. A low-speed gradual increase strategy is adopted to reduce the impact intensity during the tension introduction process. During this gradual increase, micro-amplitude alternating loosening and tightening operations are simultaneously superimposed. That is, through a precision control system, small-amplitude loosening and tightening actions are applied alternately in a periodic high-frequency manner, so that the stress response at the edge of the steel strip is in a dynamic process of micro-perturbation oscillation. Through this process, the original tensile stress field in the edge area can be loosened and induced to be slowly released, thereby reducing the risk of residual stress superposition and forming a stable and controllable tension transition zone. Furthermore, to further enhance the proactiveness of edge stress control, a micro-amplitude auxiliary roller is installed in the initial path of the steel strip entering the winding system. This auxiliary roller has a lateral disturbance function, and its working mode is to apply a very small amplitude lateral vibration displacement at the edge access point of the steel strip. The direction of this micro-amplitude disturbance can be dynamically adjusted with time or tension changes, thereby enabling the steel strip edge to obtain micro-scale mobility under rigid constraints, avoiding concentrated stress peaks caused by abrupt changes in guidance at the edge. This structure physically provides a nonlinear buffer path for the steel strip, changing the tension establishment process from initial linear loading to nonlinear flexible growth, which is conducive to the steel strip edge obtaining a stress adaptation window on a time scale and improving the edge deformation coordination capability.

[0029] In the initial stage, the grain orientation distribution of the current electrical steel strip is obtained through online or pre-set grain orientation identification methods, including grain size, orientation deviation, texture density, and their variation in the width direction. This is used as a priori reference parameter for the material deformation capacity of the edge region. Combined with known edge residual stress characteristics, a tension threshold control model is established. This model is used to determine the tension initiation threshold value at the initial stage of winding tension rise. If the grain orientation shows a significant edge agglomeration trend or the texture density increases, the tension rise initiation threshold is lowered, allowing the edge region to enter the stress release process earlier under lower tension conditions. This avoids a sharp increase in stress in the edge region under high tension, thereby achieving dynamic synchronization between the residual stress release process and the tension establishment process in the time dimension. Through this synchronization strategy, local elastoplastic abrupt changes caused by mismatch in grain alignment direction can be effectively prevented, laying a microscopic foundation for tension profile stability. In the winding section, an edge drift tolerance zone is further constructed that adjusts with the thickness of the steel strip. This tolerance zone is located within ±5 to 15 millimeters of the edge in the width direction of the steel strip. The specific value is calculated based on a threshold function set according to the steel strip thickness. When the thickness is within the upper and lower limits of the design value, the tolerance zone remains fixed. However, when the steel strip thickness fluctuates beyond the set tolerance, the tolerance zone width correction logic is triggered by the control system to dynamically adjust its range. This allows the high-thickness area to obtain a larger edge disturbance absorption zone, while the thin strip area obtains a smaller disturbance release range. This ensures that the energy of edge micro-slippage or stress disturbance under different thickness conditions is reasonably contained and does not form a reverse stress peak.

[0030] During the steel strip winding process, the steel strip often exhibits varying degrees of tension differences in the transverse direction due to the combined effects of material properties, thickness distribution in the width direction, transverse guiding errors, and changes in winding parameters. These tension differences are particularly pronounced in the edge regions. If not corrected in time, the location of the disturbance trap zone can easily deviate from the high-risk area, thereby weakening the suppression effect on critical crack initiation points. This invention establishes a real-time tension profile analysis system. Based on an online tension sensor array, it acquires the tension values ​​at various points in the transverse direction of the steel strip, calculates the instantaneous tension difference distribution map, and combines it with historical tension change trends to predict the spatiotemporal location of high-risk edge crack points. Subsequently, the originally set disturbance trap zone is corrected and adjusted, including slight positional shifts, width resets, and changes in the response intensity of the absorption mechanism, ensuring that the trap zone is always anchored in the actual crack-prone area, thereby enhancing the disturbance dissipation capacity and residual energy attenuation efficiency. Near the end of the winding process, the steel strip tension tends to concentrate and stabilize. Based on this, a profile tension compression closure mechanism is implemented, and a step-by-step convergence strategy is adopted to prevent the risk of edge cracks caused by sudden tension changes at the winding endpoint. This strategy comprises three stages. First, tension reduction control is actively applied to the edge region to release some residual edge stress by reducing edge tension, while preventing stress accumulation and the formation of spikes at the boundary during winding and tightening. Second, the tension level is moderately increased in the central region to construct a gradually increasing tension band to balance the overall tension profile. Finally, the tension value is synchronously converged across the entire profile, causing the edge and center tensions to become consistent, forming a continuous closed tension band in the transverse profile. Through this progressive compression mode—first at the edge, then at the center, and finally overall—the tension jump period is effectively delayed and shortened, allowing the edge material to have an earlier stress adaptation window.

[0031] At the end of the winding process, a linkage control method between the coil diameter ratio and the contact angle is adopted. By actively adjusting the contact state between the winding roll and the steel coil, the tension transmission path is changed, thereby optimizing the convergence speed of the tension profile. The control system calculates the diameter ratio between the inner and outer coil layers in real time based on the current coil diameter and sets a target coil diameter ratio. When the steel coil approaches the final winding stage, the core diameter is appropriately reduced while maintaining the outer ring expansion rate, thereby creating a gradient return effect of tension from the edge to the center. At the same time, a small offset adjustment is made to the contact angle between the winding roll and the steel strip. By precisely controlling the roll surface cutting angle and the contact state with the steel strip line, the edge tension compression rate is gradually increased, allowing the tension compression closure zone to form quickly in a short time. The above adjustment process aims to transform the traditional passive tension natural balance path into an active compression guiding mechanism, enabling the edge area to complete tension closure in advance at the final winding stage, compressing the time window for potential edge cracks, thereby improving the stability and structural integrity of the steel coil edge. In addition, to enhance the plastic adaptability of the edge to local stress disturbances during compression, a slight heating treatment is applied to the edge of the steel strip during tension compression, using a non-contact directional heating device for local heating. This heating process ensures that the temperature of the edge micro-region is slightly higher than that of the central region but does not exceed the material's critical annealing temperature. This induces increased dislocation activity and enhanced slip capability within the material, improving the plastic behavior and deformation coordination of the steel strip edge. Under thermal activation, it is easier to complete the stress redistribution during the tension convergence process, making the tension compression closure process smoother and more energy-efficient. Ultimately, while maintaining the compactness of the coil, the risk of edge cracking at the endpoint is effectively avoided.

[0032] Combined with appendix Figure 3The coil diameter ratio adjustment process employs a gradual reduction strategy driven by both spatial location and temporal progression. Key steps include three-stage coil diameter adjustment sequence control and three-segment length interval division. In the first stage, low-speed gradual reduction control is applied to the edge region of the steel coil. This control process calculates the target reduction rate based on the real-time coil diameter and limits it to a low-level, gradually changing range, allowing the edge to gradually reduce its diameter within a limited time. This establishes early tension release and stress buffering conditions for the edge, preventing crack initiation caused by sudden tension changes at the winding end. In the second stage, high-speed gradual reduction control is applied to the central region, causing the central tension to quickly converge with the compression zone formed at the edge, thereby reducing the lateral tension pull of the central region on the edge region and further stabilizing the edge tension profile. In the third stage, a dual-sided synchronous convergence operation is performed. The control system gradually unifies the coil diameter ratio of the edge and center sections, ultimately forming a tension-balanced compression closed zone across the entire width. In the final winding stage, the total winding length of the steel coil is divided into three segments: the initial slow-shrinking segment, the middle rapid-shrinking segment, and the final synchronous segment. Different coil diameter ratio decay rates are set within each segment. The shrinkage rate in the edge region is consistently higher than that in the middle region. The system dynamically adjusts the difference in shrinkage rates between the edge and the middle region through a curve decay function, forming a time-difference gradient path where the edge closes first and the middle region responds later throughout the final winding process. This path allows the edge to complete structural closure and tension locking before the large-scale tension contraction in the middle region, thus constructing a pre-closing zone around the edge. This protective zone plays a buffering and transfer role during the subsequent tension convergence in the middle region, reducing the probability of edge crack tip formation and the risk of tension superposition.

[0033] Near the end of the winding process, a contact angle scanning adjustment mechanism is activated. This mechanism controls the geometric angle of the contact point between the take-up roller and the steel strip. A high-precision drive unit sets the take-up roller angle to continuously change in small increments within a set range, thereby achieving gradual convergence of the tension profile edge under multiple micro-angle states. This angle perturbation allows edge stress to diffuse along multiple paths, avoiding linear stress concentration bands formed by a single contact angle. Simultaneously, during multi-angle iteration, it induces plastic slippage in the edge region, enhancing the local fluidity of the material and improving the structural coupling effect of the tension transition zone. The adjustment sequence employs an angle reversal strategy of first increasing and then decreasing. First, the contact angle is adjusted to 2–5° above the target angle to create a tension advance response zone. In this state, the local material at the steel strip edge enters a controllable micro-plastic state. Subsequently, the system slowly reverses the angle back to the target angle at a set rate. This reversal process induces plastic micro-flow behavior in the edge region, causing the previously accumulated local tension peak to attenuate and relax, ultimately forming a tension equilibrium closed state at the target angle.

[0034] A dynamic angle gradient table is constructed, and a response model between the angle adjustment rate and the real-time coil diameter is established by introducing a constructed nonlinear function. This ensures that the contact angle change has a stable gradient property during tension compression closure, thereby avoiding stress concentration and edge crack risk propagation caused by abrupt angle adjustment. During the contact angle adjustment process at the end of winding, the control system adjusts the contact angle based on the currently measured real-time coil diameter. The preset function is invoked to calculate the appropriate contact angle adjustment rate. This ensures a continuous and smooth change trend within each roll diameter threshold range, and switches rates according to different roll diameter segments, thus constructing an angle adjustment strategy with multi-level response ranges. The dynamic angle step function is based on the following nonlinear coupling expression:

[0035] in, The function representing the contact angle adjustment rate as a function of roll diameter. The current real-time volume diameter, The maximum contact angle rate limit coefficient is used to determine the upper limit of the rate boundary throughout the entire adjustment process; The angle adjustment hysteresis decay coefficient is used to control the sensitivity of the function to changes in roll diameter in the initial stage. The larger the value, the faster the early adjustment. The periodic disturbance adjustment coefficient is used to simulate the repeated fluctuations and interference effects of tension disturbance in the edge region during the angle adjustment process. This is a nonlinear coil diameter response index, describing the nonlinear impact of coil diameter increase on the angle adjustment rate. It is used to fit the dynamic demand for angle changes at the end stage of steel coils of different specifications; the disturbance term within it... This constitutes the disturbance attenuation composite factor of the function, which is used to construct the disturbance absorption mechanism in the regulation path at each convolution diameter segment. When the convolution diameter is small, this term enhances the disturbance expression to eliminate the tension peak in advance, while when the convolution diameter increases, the disturbance amplitude is naturally reduced through exponential attenuation to maintain regulation stability.

[0036] After entering the final winding stage, the system, based on the online tension monitoring and stress evolution model from the preceding process, acquires the stress distribution map of the edge micro-regions and divides them into high-stress and low-stress areas. Then, it implements temperature control in descending order of stress intensity. First, a small-scale localized temperature increase is performed on the micro-regions with the highest stress concentration at the edge. This process typically uses a mid-to-far infrared fast-response heating unit to ensure that the high-stress material locally enters a thermal softening state without affecting the overall thermal field stability, thereby enhancing its strain compatibility. Subsequently, the temperature increase range is expanded to the low-stress micro-regions, allowing a gradient plastic band to form in the overall edge region before tension convergence, providing a structural buffer for subsequent cross-sectional tension compression. Furthermore, to achieve precise coordination between the temperature increase timing and the tension convergence process, a pre-calculation mechanism for the tension convergence time constant is introduced. This time constant is derived from process parameters such as roll diameter, tension change rate, and steel strip elastic-plastic modulus, and the trigger sequence of the temperature control system is set accordingly. When the constant value is small and the system determines that the edge region does not have sufficient plastic buffer, a delayed trigger temperature control method is used to avoid incomplete closure caused by premature release of plasticity; conversely, if the constant value is large, an early trigger heating strategy is used to enable the edge material to complete plastic transformation before the tension enters the closure stage, thereby achieving active reduction of the edge stress peak.

[0037] At the final stage of winding, after the temperature control system completes the directional heating of the micro-regions at the edge of the steel strip, it immediately activates the rapid cooling module to perform a short-term cooling operation on the edge area. This cooling process uses directional airflow or a high thermal conductivity cooling medium to control the cooling rate and range, enabling the edge material to transform from a thermally softened state to a structurally delaminated state. Through this short-time cooling process, the steel strip edge forms a double-layer structure with a gradient in mechanical properties. The surface layer undergoes relative hardening after rapid cooling, possessing higher yield strength and crack resistance, while the inner layer retains a certain degree of plasticity because the heat has not been completely dissipated. This allows the edge to possess a composite strain coordination capability of external rigid support and internal flexible buffer when subjected to tensile compressive disturbances, providing a structural foundation for the subsequent tension closure process. Based on this structure, the tension compression closure mechanism is controlled in a time-sequence manner, that is, the strategy of closing the edges first and then the center is adopted. By controlling the rate of change of the roll diameter and the rate of tension adjustment, the tension is first gradually closed in a small area at the edge. The high rigidity of the outer surface layer achieves rapid stress locking, while the extensibility of the inner layer completes the tension fine adjustment, so that a stable closure zone is formed at the edge. Then the tension is extended to the central area to complete the tension balance closure of the entire profile.

[0038] Example 1: Combined with appendix Figure 4In this embodiment, during the winding process of a certain type of non-oriented silicon steel product, an electrical steel manufacturing company typically uses an initial tension loading rate of 1.2 Newtons per second. Following the tension response initial displacement method, when a batch of steel strips with a thickness of 0.35 mm and a width of 980 mm begins winding, the system reduces the initial tension loading rate to 0.36 Newtons per second, approximately 0.3 times the conventional rate. During this low-speed loading process, alternating tensioning disturbances within a range of ±1.5 Newtons are introduced through the tension control system, completing a full tensioning cycle every 8 seconds. This allows residual stress in the steel strip edge area to be gradually released, preventing abrupt stress accumulation during the initial stage and improving edge stability. Simultaneously, a micro-amplitude auxiliary roller is installed at the beginning of the winding process. This roller generates a lateral disturbance of 5 Hz per minute with an amplitude of 0.4 mm, guiding slight movement of the steel strip edge and creating a non-linear tension buffer zone. This effectively prevents the tension establishment path from being too concentrated at the edge, thus preventing sudden stress sources.

[0039] During operation, the grain structure of this batch of steel strip was analyzed using an online orientation identification instrument. It was found that the edge grains were arranged in a banded, tilted pattern with an average deflection angle of 22 degrees, while the central grains exhibited a typical equiaxed distribution. The control system delayed the initial tension increase threshold from the standard tension of 15 Newtons to 20 Newtons. This meant that the loading rate was gradually increased only when the winding tension approached 20 Newtons, thus synchronizing the tension build-up process with the release of residual stress from the edge grain structure, achieving synchronous coordination between tension and stress release.

[0040] Meanwhile, an edge drift tolerance zone is set in the middle section of the winding, with a width of ±10 mm determined based on the 0.35 mm steel strip thickness. The system is designed to allow slight expansion and contraction in this zone as long as the tension fluctuation does not exceed ±2.5 Newtons, thereby releasing local stress concentration caused by tension micro-disturbances. When the thickness monitor detects that the edge thickness of the steel strip in a certain section has locally increased to 0.38 mm, exceeding the set tolerance threshold of 0.02 mm, the system expands the width of the edge tolerance zone for that section to ±13 mm and simultaneously adjusts the tension feedback parameters to reduce its response coefficient to edge disturbances by 0.15, thereby avoiding the formation of microcracks caused by stress amplification effects.

[0041] The system uses a transverse tension distribution monitoring device positioned above the winding line to collect tension data from 20 equidistant points on the steel strip, from the left edge to the right edge, once per second. After calculating the average of the data over five consecutive seconds, the system identifies the area of ​​maximum tension deviation. During a single winding process, this area is located approximately 7 mm inward from the right edge, highly coinciding with the location of frequent microcracks in the early stages. Based on this identification, the control system dynamically adjusts the control center coordinates of the disturbance trap area, changing it from the original design of a symmetrical distribution within ±10 mm to a range of +7 mm to +17 mm to the right, ensuring that the microslip dissipation area is always synchronized with the potentially high-risk area.

[0042] During the winding process, in the final 50 meters, the tension control system activates the profile compression closure mechanism. First, in the first 20 meters, the target tension in the edge region is gradually reduced from the originally set 60 Newtons to 45 Newtons, decreasing by 3 Newtons every 5 meters. Then, in the middle 20 meters, the tension in the central region is increased from 50 Newtons to 55 Newtons, increasing by 2.5 Newtons every 5 meters, forming a reverse tension gradient structure with decreasing tension at the edges and increasing tension in the center. In the final 10 meters, the tension across the entire width simultaneously converges to the target value of 52 Newtons, completing the synchronous closure of the edge and center tensions. This ensures a uniform stress field is formed in the profile compression area, preventing breakage caused by sudden changes in edge tension when the roll diameter decreases.

[0043] To further accelerate the formation of the end tension closure zone and shorten the edge crack initiation window, the system activates a linkage adjustment program for the winding roll's diameter ratio and contact angle in the final 20 meters. The diameter ratio is set to a gradual change from 1.00 to 1.05 from the edge to the center, achieving a structure of slow winding at the edge and slightly fast winding at the center through differential speed control of the winding roll. Simultaneously, the winding roll contact angle is increased from the initial 28 degrees to 31 degrees, with an increase rate set at 0.3 degrees every 2 meters, achieving the target angle in the final 10 meters and maintaining it constant. This adjustment method significantly improves the formation rate of the edge tension compression zone, reducing the duration of the highly sensitive edge crack stage from the original 18 seconds to 9.5 seconds.

[0044] Building upon this, edge temperature control is further implemented to enhance the plastic response of the steel strip edge. An infrared radiation heating module is set to uniformly heat the area within ±15 mm of the edge from a distance of 8 cm from the steel strip surface, with a target temperature rise of 30 degrees Celsius. The system calculates a time constant of 6.5 seconds based on the tension closure response curve, initiating temperature control 8 seconds before tension convergence to ensure that the heating is completed before final tension convergence. After heating, the yield strength of the steel strip edge decreases by 7.3%, improving plastic deformation capacity, effectively absorbing the fluctuation energy during tension convergence, and preventing stress peak formation.

[0045] Example 2: Combined with appendix Figure 5Based on Example 1, the system divides the final 80-meter section of the winding into three segments: the first segment, the edge tapering segment; the second segment, the center tapering segment; and the third segment, the synchronous convergence segment. In the first segment (0-30 meters), the edge roll diameter ratio is set to decrease from 1.00 to 0.985 at a rate of 0.005 decreases per 10 meters, while the center remains constant. The edge winding roller speed is set to 240 meters per minute, forming a pre-closed edge band through slow, gradual contraction. In the second segment (30-60 meters), center contraction control is activated, rapidly reducing the center roll diameter ratio from 1.00 to 0.980 at a rate of 0.0065 decreases per 10 meters, creating a tension-counteracting band with the edge. In the third segment (60-80 meters), the edge and center simultaneously converge to a uniform roll diameter ratio of 0.975, with both sides synchronously adjusted and merged into a closed profile structure. This strategy ensures that the edges first contract to form a stress release buffer zone, and then the tension difference of the roll is gradually balanced by the central compensating tension, ultimately achieving uniform convergence of the entire roll profile and effectively shortening the window for edge crack initiation.

[0046] During this process, the contact angle adjustment employed a micro-angle scanning and pullback mechanism, gradually initiated during the remaining 20-meter winding section. Within the initial 80-70 meter range, the contact angle was increased from the standard 28 degrees to 33 degrees, in increments of 0.5 degrees every 2 meters. Subsequently, in the 70-60 meter range, the contact angle was pulled back to the target value of 28 degrees at the same pace. During the pullback, each adjustment was maintained for 2 seconds to allow for the completion of edge tension fluctuation responses. This angle adjustment logic is based on the micro-angle plasticity driving principle, which uses minute angle changes to stimulate edge plastic displacement, creating micro-flow of edge stress and allowing the potential peak stress at the edge to be released earlier. Comparative analysis of post-winding tension monitoring data showed that the peak edge tension fluctuation in the dynamic contact angle adjustment section decreased from ±7.5 Newtons to ±3.2 Newtons, indicating a significant reduction in stress concentration effects.

[0047] Further analysis of the data differences before and after adopting the strategy of linking the roll diameter ratio and contact angle revealed that the probability of edge cracking at the roll tail section decreased from 13.7% in the early stage to 1.2%, almost eliminating the formation of edge cracks. In addition, thermal imaging analysis showed that the edge temperature rise during the contact angle adjustment process was stable at 37.4 degrees Celsius, which effectively stimulated the plastic enhancement effect of the edge material.

[0048] The system establishes a dynamic contact angle adjustment rate control table that is linked to the roll diameter in real time for the last 30 meters of the winding section. The core of this table is the dynamic step function of the angle, and its mathematical model is as follows:

[0049] in, This refers to the contact angle adjustment rate, measured in degrees per second. This is the current roll diameter, in millimeters. The maximum angle adjustment rate limit coefficient is set to 0.12. The angle adjustment hysteresis attenuation coefficient is set to 0.025. This is the periodic disturbance adjustment coefficient, with a value of 0.8. The nonlinear response exponent has a value of 1.3.

[0050] During operation, the roll diameter at the take-up end gradually decreases from an initial 680 mm to 580 mm. Throughout the process, the system calculates the contact angle rate adjustment value every 10 mm decrease. (Based on roll diameter...) Taking millimeters as an example, substituting it into the formula yields:

[0051] The calculation first processes the exponential term:

[0052] Then calculate the power function term:

[0053] Then perform trigonometric function operations:

[0054] Substitute the above values ​​into the original formula:

[0055] This results in an angle adjustment rate of approximately 0.12 degrees per second when the roll diameter is 600 mm, close to the maximum set rate. Since the exponential decay term rapidly approaches zero in the later stages, the overall function tends towards a stable upper limit. Based on this, the system maintains a high-frequency, small-amplitude angle adjustment in this segment to dissipate edge disturbances. On the other hand, in stages with larger roll diameters, for example… When the angle is 680 mm, since the attenuation term has not yet weakened, the disturbance factor in the function plays a significant role in weakening the adjustment rate. The calculated angle adjustment rate is about 0.086 degrees per second. Feedback shows that the tension fluctuation amplitude is controlled within ±2.8 Newtons in this stage, which is more than 40% lower than the traditional monotonic angle contraction strategy.

[0056] During a night shift commissioning of the B35A250 electrical steel winding line, a graded temperature control and edge-locking closure scheme was introduced to improve edge crack control, addressing the issue of minor cracks appearing at the edge of the previous batch of products at the end of the winding. This batch of electrical steel strips was 0.27 mm thick and 1020 mm wide. Surface stress assessment data showed a significant stress gradient from 0 to 8 mm from the edge, with a peak edge stress of approximately 185 MPa and a middle region stress of 126 MPa. To address this, an infrared heater was used to implement micro-area temperature control at the steel strip edge, and the temperature was graded according to the edge stress distribution gradient. Specifically, the high-stress area (0-5 mm from the edge) was heated to 70 degrees Celsius, the medium-stress area (5-10 mm from the edge) was heated to 60 degrees Celsius, and the remaining area was kept at room temperature. The heating duration was controlled to 45 seconds. Simultaneously, the temperature control system activated a stress field prediction model to pre-calculate the time constant of tension convergence during the current tension compression stage. The value is 12.6 seconds. The system uses this as a benchmark to set the temperature control trigger time to be early trigger, that is, to complete the preheating process 6 seconds before the tension convergence starts, so as to ensure that the edge of the steel strip is in a state of temperature rise and enters the plastic stress release stage.

[0057] After heating is complete, a short-term cooling device is activated to rapidly cool the steel strip edge for 3 seconds, reducing the surface temperature to 35 degrees Celsius while the interior temperature remains at approximately 52 degrees Celsius due to heat retention. This creates a double-layer edge structure with a slightly hardened surface and a ductile inner layer. This structure prevents abrupt yielding at the edge during subsequent tension loading, instead allowing tension migration to be gradually absorbed through an elastoplastic synergy. Upon entering the tension compression closure process, the system initiates an edge-first closure strategy, initially controlling the tension within a 30mm radius of the edge to converge from 110 Newtons to 75 Newtons over approximately 3.5 seconds. During this process, the tension in the center remains stable. Subsequently, the system switches to the center tension closure stage, gradually reducing the center tension from 115 Newtons to 75 Newtons, and finally achieving cross-sectional mean closure synchronously with the edge at 7.8 seconds.

[0058] According to tension sensor data, no sudden tension changes occurred during the edge closure process, and the peak tension fluctuation was controlled within ±1.1 Newtons, which is far superior to the ±3.8 Newtons of the uncontrolled group. After the test paper was completed, a cross-section inspection of the steel strip revealed no microcracks, crazing, or metal gap expansion at the edge. The plastic band remained stable within a thickness range of 6 to 15 micrometers at the edge, and the hardened layer depth remained below 4 micrometers. The overall edge structure exhibited good crack resistance and ductility synergy.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for controlling winding tension profile and suppressing edge cracks in electrical steel winding, characterized in that... include: At the beginning of the winding stage, tension is applied using the tension response initial displacement method based on the previous process conditions of the electrical steel strip. This ensures that the tension establishment path and the residual stress release trend are coordinated, forming an edge buffer state. In the middle of the winding, an edge drift tolerance zone of the tension profile is constructed. By setting an unsteady elastic tolerance for tension fluctuations in the ±10 mm area of ​​the steel strip edge, the edge has limited micro-expansion and contraction capabilities to release local stress concentration. Throughout the winding process, controllable disturbances are allowed at the edge of the steel strip, and a disturbance trapping zone is set. By adjusting the structural path of the edge region, micro-slippage and local tension disturbances are attenuated and dissipated at the edge. At the winding end, a cross-sectional tension compression closure mechanism is adopted. By converging the tension difference between the edges and the center, a tension closure band is constructed at the edge to suppress the risk of edge cracking caused by critical tension disturbance when the roll diameter shrinks.

2. The method for controlling winding tension profile and suppressing edge cracks in electrical steel winding according to claim 1, characterized in that... In the tension response initial displacement method, the initial tension loading rate is 0.2-0.6 times that of the conventional rate, and the residual stress at the edge is gradually released through micro-amplitude alternating tightening and loosening operations during the loading process; in the initial stage, the edge is laterally guided by a preset micro-amplitude auxiliary roller to form a nonlinear buffer zone for tension establishment.

3. The method for controlling winding tension profile and suppressing edge cracks in electrical steel winding according to claim 1, characterized in that... The threshold for initial tension increase is adjusted according to the grain orientation distribution of the steel strip in the initial stage, so that the residual stress release process is synchronized with the winding tension establishment process; the width of the edge drift tolerance zone is adjusted to ±5 to ±15 mm according to the thickness of the steel strip, and the width of the tolerance zone is dynamically corrected when the thickness fluctuation exceeds the set value.

4. The method for controlling winding tension profile and suppressing edge cracks in electrical steel winding according to claim 1, characterized in that... Throughout the winding process, the position of the disturbance and sinking area is corrected by the difference in lateral tension of the steel strip, so that it always corresponds to the high-risk area of ​​edge cracks; the profile tension compression closure mechanism adopts a step-by-step convergence strategy at the end of the winding stage, first reducing the edge tension, then increasing the center tension, and finally converging to the mean value.

5. The method for controlling winding tension profile and suppressing edge cracks in electrical steel winding according to claim 1, characterized in that... The formation speed of the profile tension compression closure zone is increased by adjusting the winding diameter ratio and contact angle of the take-up roller at the winding end, so as to shorten the window period for edge crack initiation; the tension compression closure mechanism is combined with edge zone temperature control, which enhances the edge plasticity by slightly raising the temperature before tension convergence.

6. The method for controlling winding tension profile and suppressing edge cracks in electrical steel winding according to claim 5, characterized in that... During the winding diameter ratio adjustment process, the edges are first gradually reduced at a low speed, then the center is gradually reduced at a high speed, and finally both sides converge synchronously to form a gradient winding diameter closure method with a time difference to shorten the edge tear window period; at the winding end, the winding diameter ratio adjustment adopts the method of dividing the winding length into three segments, each segment with a different winding diameter ratio decay rate, and the edge area rate always leads the middle area to form a protective zone that closes in advance.

7. The method for controlling winding tension profile and suppressing edge cracks in electrical steel winding according to claim 5, characterized in that... The contact angle adjustment involves continuously scanning the take-up roller angle at the winding end in small amplitudes, so that the edge of the tension profile gradually converges under multiple micro-angle states, reducing stress concentration at a single angle. In the contact angle adjustment, it is first adjusted to be 2–5° larger than the target angle, and then reversed back to the target angle to generate edge plastic micro-flow and eliminate stress peaks in advance.

8. The method for controlling winding tension profile and suppressing edge cracks in electrical steel winding according to claim 5, characterized in that... During the contact angle adjustment process, a dynamic step table for angle is calculated in real time according to the roll diameter. The angle adjustment rate is switched at each roll diameter threshold to maintain the angle change gradient throughout the tension compression closure process. The dynamic step table for angle is a graded control table that pre-sets the contact angle and corresponding adjustment rate according to different roll diameter thresholds. It is used to switch the contact angle adjustment rate when the roll diameter changes to maintain the angle change gradient during the tension compression closure process.

9. The method for controlling winding tension profile and suppressing edge cracks in electrical steel winding according to claim 5, characterized in that... The temperature control process is based on the stress distribution in the edge micro-regions, with the high-stress micro-regions being heated locally first, and then extended to the low-stress micro-regions. The tension convergence time constant is calculated in advance between the edge heating and the tension convergence, and the plastic state is obtained by delaying or advancing the temperature control trigger.

10. The method for controlling winding tension profile and suppressing edge cracks in electrical steel winding according to claim 5, characterized in that... After the temperature control is completed, the edge is cooled for a short time to harden the surface layer and keep the inner layer plastic, so as to form a double-layer edge structure. The tension compression closure process adopts the sequence of closing the edge first and then the center. First, a small-range tension closure is completed at the edge, and then the full-width closure is completed in the middle, so that the edge is locked in a stress state first.

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