A solder wire continuous drawing diameter closed-loop control method and system

Abstract

The present application relates to the technical field of wire processing automation, and particularly relates to a solder wire continuous drawing diameter closed-loop control method and system. The method comprises the following steps: obtaining the actual diameter of wire at the outlet of each drawing die; determining the diameter deviation of each die stage according to the actual diameter of wire and the pre-stored theoretical outlet diameter; when the diameter deviation of any die stage exceeds the corresponding local deviation threshold, generating a local compensation instruction; issuing the local compensation instruction to the local actuator of the immediately adjacent section downstream of the corresponding drawing die, adjusting the local pulling speed of the section, so that the actual diameter of wire subsequently passing through the drawing die approaches the theoretical outlet diameter. Through distributed die stage detection and local speed closed-loop adjustment, the present application realizes deviation tracing and sectional compensation, avoids tension distortion and wire breakage caused by end-to-end adjustment, and improves the diameter control precision and stability.

Description

Technical Field

[0001] This invention relates to the field of automation technology for wire processing, and in particular to a closed-loop control method and system for continuous wire drawing diameter of solder wire. Background Technology

[0002] On a continuous multi-die solder wire drawing production line, coarse solder rods are progressively reduced in diameter by passing through multiple drawing dies arranged in series, and finally wound into finished wire by a final traction wheel. To control diameter accuracy, existing production lines typically equip a laser diameter gauge after the last die, feeding back the detected diameter deviation to the traction motor to form a single-point closed-loop control. This architecture can be maintained in batch production with stable specifications and constant operating conditions, but in daily scenarios where dies wear progressively, its control accuracy and stability face fundamental limitations.

[0003] Specifically, the dies arranged in series operate under different conditions, causing the actual reduction rate of the wire at different dies to deviate from the theoretical value, resulting in a progressively accumulating diameter deviation. Existing single-point end-point diameter measurement can only obtain the final diameter after the combined effect of all dies, and cannot distinguish the distribution of this accumulated error in the die chain. When the final diameter exceeds the tolerance, the operator can only adjust the end-point traction speed based on experience. This one-size-fits-all compensation method distorts the tension distribution of the entire die chain, causing the wire at the front end to break due to overload. Summary of the Invention

[0004] Therefore, it is necessary for the present invention to provide a closed-loop control method and system for continuous solder wire drawing diameter to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, a closed-loop control method for the continuous wire drawing diameter of solder wire includes the following steps:

[0006] Obtain the measured diameter of the wire at the exit of each drawing die;

[0007] Based on the measured diameter of each wire and the pre-stored theoretical exit diameter, the diameter deviation of each mold stage is determined; when the diameter deviation of any mold stage exceeds the corresponding local deviation threshold, a local compensation instruction is generated.

[0008] The local compensation command is sent to the local actuator in the downstream adjacent section of the corresponding wire drawing die to adjust the local traction speed of that section so that the measured diameter of the wire passing through the wire drawing die is close to the theoretical exit diameter.

[0009] The downstream section of the wire drawing die is equipped with an independent traction drum, and the adjustment of the local traction speed is constrained by the tension overload protection of the adjacent section; the local deviation threshold is preset according to the historical wear record of the corresponding wire drawing die and the calibrated value of the wire drawing liquid film thickness.

[0010] Preferably, the present invention also provides a closed-loop control system for the continuous wire drawing diameter of solder wire, the system comprising:

[0011] Multiple wire drawing dies arranged in series;

[0012] Multiple laser diameter measuring instruments are respectively installed at the exit of each of the wire drawing dies;

[0013] Multiple independent traction drums are respectively configured in the downstream adjacent section of each wire drawing die, serving as local actuators;

[0014] Multiple tension detection devices are respectively installed in the downstream adjacent section of each of the wire drawing dies;

[0015] Multiple wire drawing liquid film thickness detection devices are respectively installed at the entrance of each of the wire drawing dies;

[0016] Multiple drawing fluid supply mechanisms are respectively configured for each of the drawing dies;

[0017] Memory;

[0018] The controller is communicatively connected to the laser diameter measuring instrument, the independent traction drum, the tension detection device, the wire drawing liquid film thickness detection device, the wire drawing liquid supply mechanism, and the memory, respectively, so that the system executes the closed-loop control method for continuous solder wire drawing diameter as described above.

[0019] The beneficial effects of this invention are as follows:

[0020] On the one hand, by obtaining the measured diameter of the wire at the exit of each drawing die and determining the die-level diameter deviation, the single-point detection at the end of the existing technology, which can only sense the comprehensive diameter at the end, is transformed into a distributed traceability identification of the diameter reduction error at each stage in the die chain. This breaks through the limitation that the end diameter measurement cannot distinguish the distribution of the cumulative error in the die chain, and the location of the diameter deviation can be accurately located.

[0021] On the other hand, by issuing local compensation commands only to the local actuators of the corresponding downstream adjacent section of the mold for local traction speed adjustment, the existing technology of mid-to-end end-to-end compensation is transformed into local closed-loop adjustment targeting the deviation source section. This avoids the distortion of the tension distribution of the entire mold chain caused by overall adjustment and fundamentally suppresses the risk of wire breakage due to tension overload at the front end.

[0022] On the other hand, by introducing tension overload protection constraints in adjacent sections to limit the adjustment of local traction speed, while achieving local compensation for die-level deviations, tension coordination and speed synchronization between adjacent sections are ensured, so that local compensation actions and overall tension stability can be taken into account, thereby improving the overall control stability of the continuous wire drawing process. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings:

[0024] Figure 1 A flowchart illustrating the steps of a closed-loop control method for continuous solder wire drawing diameter according to an embodiment is shown.

[0025] Figure 2 The overall hardware layout of a continuous multi-die solder wire drawing production line according to one embodiment is shown. Detailed Implementation

[0026] The technical method of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] Furthermore, the accompanying drawings are merely illustrative of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0028] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] In this case, Figure 2The overall hardware layout of a continuous multi-die solder wire drawing production line is shown. Coarse solder rods pass sequentially through drawing dies 1 to N arranged in series along the wire's travel direction. After being gradually reduced in diameter by each die, the wire is wound into finished wire by an end-rewinding device. A drawing fluid supply mechanism and a liquid film thickness detection device are located upstream of the inlet of each drawing die to supply drawing fluid and monitor the inlet liquid film thickness. A laser diameter gauge is located downstream of the outlet of each drawing die to detect the wire diameter at the die's outlet online. An independent traction drum and a tension detection device are located in the adjacent section downstream of each drawing die, serving as the local actuator and tension monitoring unit for that section, respectively. The controller communicates with the laser diameter gauge, independent traction drum, tension detection device, liquid film thickness detection device, drawing fluid supply mechanism, and end-rewinding device associated with each drawing die via a field communication bus. The controller also communicates with a memory to achieve distributed detection of the outlet diameter of each die, independent adjustment of local traction speed, and real-time monitoring of the overall line tension.

[0030] It should be noted that, Figure 2 For illustrative purposes only, the number of wire drawing dies, the model and installation position of each sensor, the type of communication bus, and the specific connection method between each hardware module and the controller can all be adjusted or replaced according to the actual production line scale, process requirements, and hardware platform, and their functional implementation is covered within the protection scope of this invention.

[0031] To achieve the above objectives, please refer to Figures 1 to 2 This invention provides a closed-loop control method for the continuous wire drawing diameter of solder wire, comprising the following steps:

[0032] S100: Obtain the measured diameter of the wire at the exit of each drawing die;

[0033] S200: Determine the diameter deviation of each mold stage based on the measured diameter of each wire and the pre-stored theoretical exit diameter; when the diameter deviation of any mold stage exceeds the corresponding local deviation threshold, generate a local compensation command;

[0034] S300: The local compensation command is sent to the local actuator in the downstream adjacent section of the corresponding wire drawing die to adjust the local traction speed of the section so that the measured diameter of the wire passing through the wire drawing die is close to the theoretical exit diameter.

[0035] The downstream section of the wire drawing die is equipped with an independent traction drum, and the adjustment of the local traction speed is constrained by the tension overload protection of the adjacent section; the local deviation threshold is preset according to the historical wear record of the corresponding wire drawing die and the calibrated value of the wire drawing liquid film thickness.

[0036] Preferably, the measured diameter of the wire at the exit of each drawing die in S100 includes S101-S102.

[0037] S101: A laser diameter measuring instrument is installed at the exit of each drawing die to obtain the original optical diameter of the wire when the drawing liquid film is attached to the surface of the wire.

[0038] In some embodiments, the laser diameter gauge employs a non-contact laser scanning diameter measurement principle and is arranged at a predetermined distance downstream of the exit of each drawing die along a direction perpendicular to the wire's travel direction. The predetermined distance is determined based on the vibration attenuation characteristics of the wire after exiting the die, and is typically set to 50mm to 200mm to ensure that the wire remains stable as it passes through the measurement area of ​​the laser diameter gauge, thus avoiding measurement errors caused by vibration at the moment of exiting the die.

[0039] For example, for a certain wire drawing die, its theoretical exit diameter is 0.50 mm, and the initial jitter amplitude when the wire exits the die is approximately ±0.3 mm. Considering that the effective measuring spot diameter of a laser diameter gauge is typically 1 mm to 2 mm, if the diameter gauge is placed close to the die exit, the wire jitter will frequently deviate from the center of the measuring spot, causing the diameter measurement signal to be interrupted or jump. Therefore, the laser diameter gauge can be set 150 mm downstream of the die exit along the wire's travel direction. This preset distance of 150 mm is determined based on the free sag attenuation characteristics of the wire in this section. After the wire exits the die, under the combined action of surface tension and air damping, the high-frequency jitter at the moment of exiting the die attenuates to within ±0.05 mm after traveling approximately 100 mm to 150 mm. At this point, the wire is in a stable state when passing through the measurement area of ​​the diameter gauge, which avoids measurement errors caused by jitter and does not introduce additional wire sag interference due to excessive distance, thus ensuring the accurate acquisition of the original optical diameter by the laser diameter gauge.

[0040] In some embodiments, since the solder wire needs to be continuously supplied with drawing fluid to the drawing die inlet via a drawing fluid supply mechanism for lubrication and cooling during the drawing process, a layer of drawing fluid film will adhere to the surface of the wire after it passes through the die. The original optical diameter refers to the diameter value directly measured by a laser diameter gauge through optical scanning of the outer contour of the wire surface when the drawing fluid film is attached. This original optical diameter includes the sum of the wire body diameter and the thickness of the drawing fluid film.

[0041] For example, at the exit of a certain wire drawing die, a laser diameter gauge measures the original optical diameter of the wire to be 0.52 mm. At this time, a wire drawing liquid film is attached to the surface of the wire. This original optical diameter is not the actual metal diameter of the wire, but the superposition value of the diameter of the wire's metal body and the thickness of the surface wire drawing liquid film.

[0042] In some embodiments, the sampling frequency of the laser diameter gauge is adapted to the wire travel speed to ensure that a sufficient density of diameter sampling points is obtained during the continuous travel of the wire. Optionally, when the wire travel speed is 5 m / s, the sampling frequency of the laser diameter gauge is set to no less than 1000 Hz to ensure that at least one effective diameter data is obtained per millimeter of wire length.

[0043] S102: Based on the original optical diameter and the pre-stored drawing liquid film thickness calibration value, the original optical diameter is corrected for liquid film thickness to obtain the actual measured diameter of the wire.

[0044] In some embodiments, the purpose of the liquid film thickness correction is to eliminate the influence of the drawing liquid film on the diameter measurement. Specifically, the measured diameter of the filament is obtained by subtracting the thickness contribution of the drawing liquid film in the diameter direction from the original optical diameter; wherein the thickness contribution of the drawing liquid film in the diameter direction is twice the calibrated value of the drawing liquid film thickness, which refers to the thickness of the drawing liquid film on one side of the filament.

[0045] In some embodiments, the calibrated value of the drawing fluid film thickness is obtained by pre-calibrating the drawing fluid supply pressure and wire travel speed of the corresponding drawing die. During calibration, multiple sets of actual fluid film thickness samples corresponding to different combinations of drawing fluid supply pressure and wire travel speed are collected under steady-state conditions. A correspondence table between the drawing fluid supply pressure, wire travel speed, and the calibrated value of the drawing fluid film thickness is established and stored in the memory. During actual operation, the controller queries the correspondence table based on the real-time drawing fluid supply pressure and real-time wire travel speed of the current drawing die to obtain the calibrated value of the drawing fluid film thickness under the current operating conditions.

[0046] For example, a laser diameter gauge at the exit of a wire drawing die measures the original optical diameter as 0.52 mm. The controller, based on the current wire drawing fluid supply pressure of 0.3 MPa and the wire travel speed of 5 m / s, consults the corresponding relationship table to obtain the calibrated value of the wire drawing fluid film thickness for this die as 0.01 mm. The controller then corrects the original optical diameter for the fluid film thickness, subtracting the total fluid film thickness of 0.02 mm from both sides, resulting in a measured wire diameter of 0.50 mm.

[0047] The thickness calibration value of the drawing fluid film is obtained in advance based on the drawing fluid supply pressure and wire travel speed of the corresponding drawing die.

[0048] In some embodiments, the calibration value of the drawing fluid film thickness is predetermined during the production line commissioning phase or after mold replacement and maintenance using an offline sampling calibration method. Calibration personnel adjust the drawing fluid supply pressure and wire travel speed of the corresponding drawing mold to the target steady-state condition and maintain this for a preset time. After the fluid film adhesion stabilizes, a section of wire passing through the mold outlet is cut as a calibration sample. The diameter of the metal body after removing the surface drawing fluid from the calibration sample is obtained using precision measurement methods, and the original optical diameter measured by a laser diameter gauge under this condition is recorded. Half the difference between the original optical diameter and the metal body diameter is the calibration value of the drawing fluid film thickness under this steady-state condition.

[0049] In some embodiments, to cover the actual production conditions, calibration personnel adjust the drawing fluid supply pressure and the wire travel speed according to a preset pressure gradient and speed gradient matrix combination, repeatedly performing the above-mentioned offline sampling calibration process to obtain multiple sets of drawing fluid film thickness calibration values ​​under different conditions. The controller establishes a correspondence table of each set of operating parameters and their corresponding drawing fluid film thickness calibration values ​​and stores it in the memory; the operating parameters include the drawing fluid supply pressure and the wire travel speed.

[0050] For example, for a certain wire drawing die, the wire drawing fluid supply pressure is set to 0.2MPa, 0.3MPa, and 0.4MPa, and the wire travel speed is set to 3m / s, 5m / s, and 7m / s, forming nine steady-state operating conditions in pairs. Under each operating condition, a wire sample is cut and the surface wire drawing fluid is cleaned. The diameter of the metal body is measured to be 0.498mm using a micrometer, and the original optical diameter is measured to be 0.518mm online using a laser diameter gauge. Therefore, the calibrated value of the wire drawing fluid film thickness under this operating condition is (0.518mm - 0.498mm) / 2, which is 0.01mm.

[0051] Preferably, the generation of local compensation instructions in S200 includes S201-S205.

[0052] S201: Obtain the direction and absolute value of the mold-level diameter deviation;

[0053] In some embodiments, the die-level diameter deviation is the difference between the measured diameter of the wire at the exit of the corresponding wire drawing die and the pre-stored theoretical exit diameter. The direction characterizes the deviation tendency of the measured wire diameter relative to the theoretical exit diameter; specifically, when the measured wire diameter is greater than the theoretical exit diameter, the die-level diameter deviation is positive, indicating that the wire diameter is too large; when the measured wire diameter is less than the theoretical exit diameter, the die-level diameter deviation is negative, indicating that the wire diameter is too small. The absolute value is the numerical magnitude of the die-level diameter deviation, i.e., the absolute value of the difference between the measured wire diameter and the theoretical exit diameter, used to quantify the degree of diameter deviation at the die exit.

[0054] For example, if the theoretical exit diameter of a certain wire drawing die is 0.50 mm, and the currently measured diameter of the wire is 0.52 mm, then the die-level diameter deviation is 0.02 mm, in the positive direction, with an absolute value of 0.02 mm. As another example, when the measured diameter of the wire is 0.48 mm, the die-level diameter deviation is -0.02 mm, in the negative direction, with an absolute value of 0.02 mm.

[0055] S202: When the mold-level diameter deviation indicates that the measured diameter of the wire is greater than the theoretical exit diameter, the adjustment direction of the local traction speed is determined to be an increase in speed;

[0056] In some embodiments, when the die-level diameter deviation is positive, it indicates that the current drawing die is insufficient in reducing the diameter of the wire, and the measured diameter of the wire after exiting the die is greater than the target value. In continuous wire drawing processes, the traction speed in the downstream section of the die directly affects the drawing stress borne by the wire in the die deformation zone; when the traction speed is too low, the drawing stress is small, and the plastic flow of the wire metal is insufficient, resulting in a larger exit diameter. Therefore, the controller determines that the adjustment direction of the local traction speed is to increase the speed, that is, to increase the rotational speed of the independent traction drum in the downstream adjacent section of the drawing die, so as to increase the drawing stress, ensure sufficient diameter reduction of the wire in the die deformation zone, and thus make the measured diameter of the wire passing through the drawing die subsequently approach the theoretical exit diameter.

[0057] For example, the theoretical exit diameter of a certain wire drawing die is 0.50 mm, the current measured diameter of the wire is 0.52 mm, and the die-level diameter deviation is +0.02 mm in the positive direction. Based on this, the controller determines to adjust the local traction speed of the downstream adjacent section of the die, for example, increasing the current traction speed from 5.0 m / s to 5.2 m / s, to enhance the drawing and diameter reduction effect of the die, causing the subsequent measured diameter of the wire to converge towards 0.50 mm.

[0058] S203: When the mold-level diameter deviation indicates that the measured diameter of the wire is less than the theoretical exit diameter, the adjustment direction of the local traction speed is determined to be a reduction.

[0059] In some embodiments, when the die-level diameter deviation is negative, it indicates that the current drawing die is excessively reducing the diameter of the wire, and the measured diameter of the wire after exiting the die is smaller than the theoretical exit diameter. In continuous wire drawing processes, when the traction speed in the downstream section of the die is too high, the drawing stress increases, and the metal plastic flow of the wire in the die deformation zone is excessive, resulting in a smaller exit diameter. Therefore, the controller determines that the adjustment direction of the local traction speed is to reduce the speed, that is, to reduce the rotational speed of the independent traction drum in the downstream adjacent section of the die, so as to reduce the drawing stress, alleviate the excessive diameter reduction of the wire in the die deformation zone, and thus make the measured diameter of the wire passing through the drawing die subsequently approach the theoretical exit diameter.

[0060] For example, the theoretical exit diameter of a certain wire drawing die is 0.50 mm, the current measured diameter of the wire is 0.48 mm, and the die-level diameter deviation is -0.02 mm in the negative direction. Based on this, the controller determines to perform a speed reduction adjustment on the local traction speed of the section immediately downstream of the die, for example, reducing the current traction speed from 5.0 m / s to 4.8 m / s, in order to weaken the drawing diameter reduction effect of the die and cause the subsequent measured diameter of the wire to converge towards 0.50 mm.

[0061] S204: Determine the adjustment range of the local traction speed based on the ratio of the absolute value to the corresponding local deviation threshold;

[0062] In some embodiments, the local deviation threshold is preset based on the historical wear record of the corresponding wire drawing die and the calibrated value of the wire drawing liquid film thickness. The historical wear record includes the cumulative wire drawing length and wear rate of the wire drawing die since the last maintenance. The higher the wear degree, the tighter the local deviation threshold is towards the upper limit of the allowable range, so as to trigger compensation in advance. The controller calculates the ratio of the absolute value to the local deviation threshold, which represents the relative magnitude of the current diameter deviation relative to the allowable range. The adjustment amplitude is positively correlated with the ratio, that is, the larger the ratio, the larger the adjustment amplitude, so as to achieve rapid convergence of larger deviations. At the same time, the adjustment amplitude is constrained by a preset maximum adjustment step size to avoid excessive single adjustment amount causing drastic fluctuations in the tension of the downstream section.

[0063] For example, in the downstream section immediately adjacent to a wire drawing die, the current traction speed is 5.0 m / s, the current wire tension is 120 N, and the preset safety tension threshold is 130 N. Considering that the solder wire is relatively soft and has limited tensile strength, and that the independent traction drum has a mechanical response lag of approximately 200 ms from receiving the command to stabilizing its speed, if the single adjustment step is too large, the dynamic tension during the drum's acceleration process, combined with the steady-state tension, can easily exceed the safety threshold. Therefore, the preset maximum adjustment step can be set to 4% of the current traction speed (i.e., 0.2 m / s). This value is obtained by rounding down to half the theoretical speed increment (approximately 0.42 m / s) corresponding to the difference between the preset safety tension threshold and the current wire tension (10 N). This retains the ability to respond quickly to large deviations while keeping the dynamic tension increment caused by a single speed change within the safety tension margin, thus preventing the downstream section from experiencing tension overload and wire breakage due to drastic fluctuations in traction speed.

[0064] For example, if the local deviation threshold of a certain wire drawing die is 0.03 mm, and the absolute value of the current die-level diameter deviation is 0.045 mm, then the ratio is 1.5. The controller determines the adjustment range of the local traction speed to be 3% of the current reference traction speed, i.e., 0.15 m / s, based on this ratio. If the current reference traction speed is 5.0 m / s and an acceleration adjustment is required, then the target traction speed carried by the local compensation command is 5.15 m / s.

[0065] S205: Generate the local compensation command based on the adjustment direction and the adjustment amplitude, the local compensation command carrying the target traction speed.

[0066] In some embodiments, the local compensation command is a digital control command issued by the controller to the independent traction drum in the adjacent section downstream of the corresponding wire drawing die. The controller calculates the target traction speed based on the adjustment direction (increase or decrease) determined in step S202 or S203 and the adjustment range determined in step S204; the target traction speed is the speed value obtained by adding the adjustment range to the current section traction speed. The local compensation command is encapsulated using a preset communication protocol and includes the target traction speed, the corresponding section identifier, and a command timestamp, so that the independent traction drum can receive, parse, and execute speed adjustment.

[0067] In some embodiments, the local compensation command differs from the uniform traction speed adjustment command applied to the entire production line in the prior art. It only applies to the downstream section of the specific mold that produces the diameter deviation, thus avoiding global disturbance to the tension distribution of the entire production line. The target traction speed, as the core parameter of the local compensation command, directly determines the rotational speed setting value of the independent traction drum in the next control cycle.

[0068] For example, if the current traction speed of the section immediately downstream of a wire drawing die is 5.0 m / s, step S202 determines the adjustment direction to be acceleration, and step S204 determines the adjustment range to be 0.15 m / s, then the controller calculates the target traction speed as 5.15 m / s and generates a local compensation command, which is then sent to the independent traction drum in that section. Upon receiving the command, the independent traction drum adjusts its rotational speed to correspond to the target traction speed of 5.15 m / s, thereby increasing the drawing stress at the die and causing the measured diameter of the subsequent wire to converge towards the theoretical exit diameter.

[0069] In some embodiments, before issuing the local compensation command, the controller first queries the tension safety verification result in steps S211-S213; if the target traction speed has been corrected to the safe traction speed, then the calculated value is replaced by the safe traction speed as the target traction speed carried by the local compensation command.

[0070] Preferably, the adjustment of the local traction speed is constrained by the tension overload protection of adjacent sections, including S401-S403.

[0071] S401: Obtain the current traction speed of the downstream adjacent section of the corresponding wire drawing die, and the current traction speed of the adjacent upstream section;

[0072] In some embodiments, the downstream adjacent section of the corresponding wire drawing die refers to the section immediately following the exit of the corresponding wire drawing die along the wire travel direction, and this section is driven by the independent traction drum disposed therein; the current traction speed is the actual linear speed of the independent traction drum in the current control cycle, which is obtained in real time by the controller through the encoder feedback signal or the frequency converter speed feedback signal of the independent traction drum. The adjacent upstream section refers to the section immediately preceding the entrance of the corresponding wire drawing die along the wire travel direction, and this section is also equipped with an independent traction drum, whose current traction speed is obtained in real time by the controller in the same manner.

[0073] In some embodiments, obtaining the current traction speed of the two sections is intended to provide a reference parameter for subsequent flow rate conservation calculations. Since the drawing dies arranged in series are connected by wire, when the traction speed of the downstream adjacent section is adjusted by a local compensation command, the flow rate of the wire at the corresponding drawing die changes accordingly. The adjacent upstream section must adjust its traction speed accordingly to maintain a flow rate match with the downstream adjacent section; otherwise, the wire tension between the two sections will change drastically, leading to tension overload or relaxation.

[0074] For example, in a production line containing three tandem drawing dies, dies A, B, and C are arranged sequentially along the wire travel direction. When a local compensation command is generated for die B, the controller obtains the current traction speed of the downstream adjacent section of die B (i.e., the section between die B and die C), denoted as 5.0 m / s; simultaneously, it obtains the current traction speed of the adjacent upstream section of die B (i.e., the section between die A and die B), denoted as 4.8 m / s.

[0075] S402: After adjusting the local traction speed of the downstream adjacent section according to the local compensation command and the current traction speed of the downstream adjacent section, calculate the theoretical following speed of the adjacent upstream section based on the second flow conservation, and use it as a reference benchmark for the tension overload protection constraint.

[0076] In some embodiments, the controller first sends the target traction speed carried in the local compensation command to the independent traction drum of the downstream adjacent section, adjusting the local traction speed of that section from its current value to the target traction speed. After completing the local traction speed adjustment of the downstream adjacent section, the controller calculates the theoretical following speed of the adjacent upstream section based on the principle of flow rate conservation per second; the flow rate conservation per second refers to the principle that the volume of metal entering the die per unit time is equal to the volume of metal leaving the die at the wire drawing die. Since the cross-sectional area of ​​the wire decreases after the die reduces its diameter, in order to maintain volume conservation, the traction speed of the downstream adjacent section must be greater than the traction speed of the adjacent upstream section; when the traction speed of the downstream adjacent section is adjusted, the traction speed of the adjacent upstream section should theoretically change synchronously according to the ratio of the cross-sectional areas of the die inlet and outlet.

[0077] In some embodiments, the controller multiplies the adjusted traction speed of the adjacent downstream section by the square of the ratio of the theoretical diameter of the downstream outlet to the theoretical diameter of the upstream inlet, to obtain the theoretical following speed of the adjacent upstream section. This theoretical following speed serves as a reference benchmark for the tension overload protection constraint, and is compared with the current traction speed of the adjacent upstream section to determine whether the upstream section needs adjustment, thereby preventing tension overload or relaxation of the wire at the corresponding drawing die due to mismatch between upstream and downstream speeds.

[0078] For example, if the theoretical upstream inlet diameter of a wire drawing die is 0.70 mm and the theoretical downstream outlet diameter is 0.50 mm, then the ratio of the theoretical downstream outlet diameter to the theoretical upstream inlet diameter is approximately 0.50 / 0.70 ≈ 0.714, and its square is approximately 0.510. Before adjustment, the current traction speed of the downstream adjacent section is 5.0 m / s. According to the conservation of flow rate per second, the current traction speed of the adjacent upstream section should be approximately 5.0 m / s × 0.510 ≈ 2.55 m / s. The local compensation command adjusts the traction speed of the downstream adjacent section from 5.0 m / s to 5.15 m / s, and the controller calculates the theoretical following speed of the adjacent upstream section as approximately 5.15 m / s × 0.510 ≈ 2.63 m / s.

[0079] S403: When the deviation between the theoretical following speed and the current traction speed of the adjacent upstream section exceeds a preset speed synchronization threshold, a following speed adjustment command is sent to the independent traction drum of the adjacent upstream section to make the traction speed of the adjacent upstream section approach the theoretical following speed.

[0080] In some embodiments, the preset speed synchronization threshold is pre-set based on the elastic modulus, cross-sectional area, and maximum allowable tension of the filament in the adjacent upstream section, representing the critical value of upstream-downstream speed mismatch that the filament in the adjacent upstream section can withstand within the tension safety range. The controller calculates the absolute value of the difference between the theoretical following speed and the current traction speed of the adjacent upstream section to obtain the speed deviation. When the speed deviation exceeds the preset speed synchronization threshold, it indicates that the local compensation command has caused upstream-downstream speed mismatch at the corresponding drawing die. If the adjustment is not made in time, the filament in the adjacent upstream section will break due to tension overload or pile up due to tension relaxation. At this time, the controller generates a following speed adjustment command and sends it to the independent traction drum of the adjacent upstream section. The following speed adjustment command carries the theoretical following speed as the target traction speed, causing the independent traction drum of the upstream section to adjust its rotation speed, converging the traction speed of the adjacent upstream section towards the theoretical following speed, so as to restore the flow rate conservation at the corresponding drawing die and ensure that the local compensation action is performed under the overall tension stability constraint.

[0081] Preferably, the method further includes steps S501-S503.

[0082] S501: Obtain the cumulative wire drawing length of the corresponding wire drawing die since the last maintenance;

[0083] In some embodiments, the cumulative wire drawing length refers to the total length of wire traveled through the deformation zone of the corresponding wire drawing die since the last maintenance; the last maintenance includes operations such as die replacement, die repair, or repolishing to restore the die's designed cavity dimensions. The controller calculates the cumulative wire drawing length by reading the encoder pulse accumulation value of the independent traction drum in the downstream adjacent section of the die and combining it with the circumference parameter of the independent traction drum; alternatively, the controller reads the wire travel speed synchronously collected by the laser diameter measuring instrument at the die exit and integrates and accumulates the running time to obtain the cumulative wire drawing length. After each maintenance operation is performed on the wire drawing die, a maintenance completion signal is sent to the controller through the human-machine interface. The controller resets the cumulative wire drawing length to zero and restarts the accumulation, while simultaneously writing the timestamp and maintenance type of this maintenance into the historical wear record in the memory.

[0084] For example, a wire drawing die underwent maintenance and was replaced with a new one on January 1, 2024. From that date, the controller cumulatively recorded the wire length passing through the die via the encoder of the independent traction drum. As of the current moment, the cumulative wire drawing length, converted from the encoder's cumulative pulses, is... Meters. This cumulative wire drawing length serves as an input parameter for determining the die wear trend level in subsequent step S502.

[0085] S502: Determine the die wear trend level based on the cumulative wire drawing length and the wear rate in the historical wear record;

[0086] In some embodiments, the historical wear record is stored in the memory, including the wear rate measured in previous operating cycles of the corresponding wire drawing die; the wear rate refers to the increase in the effective cavity diameter caused by each unit of cumulative wire drawing length of the wire drawing die, reflecting the wear characteristics of the die material under specific wire drawing conditions. The controller multiplies the cumulative wire drawing length by the wear rate to obtain the cumulative wear equivalent; the cumulative wear equivalent characterizes the cumulative change in cavity size caused by wear since the last maintenance. Based on the comparison result of the cumulative wear equivalent and a preset grading threshold, the controller determines the wear trend level of the die.

[0087] In some embodiments, the die wear trend level characterizes the cumulative degree of deviation of the corresponding wire drawing die from the designed cavity size. A higher level indicates more severe die wear, and the wire exit diameter is more likely to deviate from the theoretical exit diameter. The preset grading threshold is pre-set based on the die material, the hardness of the wire being processed, and the lubrication performance of the drawing fluid, and is typically divided into three levels: low, medium, and high. When the cumulative wear equivalent is less than the first grading threshold, the wear trend level is determined to be low; when it is between the first and second grading thresholds, it is determined to be medium; and when it is greater than the second grading threshold, it is determined to be high.

[0088] For example, the wear rate recorded in the historical wear record of a certain wire drawing die is: mm / m. The current cumulative wire drawing length is If m, then the cumulative wear equivalent is 3mm. If the first grading threshold is 1mm and the second grading threshold is 2mm, then the cumulative wear equivalent exceeds the second grading threshold, and the controller determines that the mold wear trend level is high.

[0089] S503: Dynamically adjust the local deviation threshold according to the mold wear trend level;

[0090] In some embodiments, the allowable upper limit is the maximum positive diameter deviation value allowed by the corresponding wire drawing die in the process specification, representing the limit tolerance of the wire exit diameter exceeding the theoretical exit diameter. As the die wear trend level increases, the die cavity systematically expands due to wear, resulting in a continuously larger trend of baseline deviation in the wire exit diameter. If the local deviation threshold remains unchanged at its initial setting, the controller will frequently trigger local compensation for this trend deviation, causing repeated adjustments of the independent traction drum and exacerbating the tension fluctuation of the entire line. Therefore, the controller queries a pre-stored threshold adjustment coefficient table according to the die wear trend level. The higher the wear trend level, the larger the threshold adjustment coefficient. The initial setting value of the local deviation threshold is multiplied by the threshold adjustment coefficient to obtain the dynamically adjusted local deviation threshold. The closer the dynamically adjusted local deviation threshold is to the allowable upper limit, that is, the closer it is to the value of the allowable upper limit, so that the local compensation triggering condition is limited to a sudden large deviation close to the process limit during the severe wear stage, avoiding excessive local compensation for the trend wear deviation. The trend wear deviation is adapted separately by the theoretical exit diameter update mechanism in steps S701-S702.

[0091] For example, the allowable upper limit for a certain wire drawing die is 0.05mm, and the initial setting value of the local deviation threshold is 0.03mm. When the die wear trend level is low, the corresponding threshold adjustment coefficient is 1.0, and the dynamically adjusted local deviation threshold remains at 0.03mm; when the wear trend level is medium, the corresponding threshold adjustment coefficient is 1.17, and the dynamically adjusted local deviation threshold is 0.035mm; when the wear trend level is high, the corresponding threshold adjustment coefficient is 1.33, and the dynamically adjusted local deviation threshold is 0.04mm. The controller uses the adjusted local deviation threshold for the out-of-tolerance judgment in the subsequent step S200, so that the die with severe wear only triggers local compensation when the diameter deviation is close to the allowable upper limit, suppressing frequent malfunctions caused by the trend wear baseline offset.

[0092] The higher the wear trend level, the tighter the local deviation threshold becomes towards the allowable upper limit of the mold-level diameter deviation.

[0093] Preferably, when multiple mold-level diameter deviations simultaneously exceed the corresponding local deviation threshold, the method further includes steps S601-S602.

[0094] S601: Generate multiple local compensation commands in descending order of the absolute value of the diameter deviation of each mold level and issue them sequentially;

[0095] In some embodiments, when the diameter deviation of each of the multiple drawing dies arranged in series simultaneously exceeds the corresponding local deviation threshold, if the controller simultaneously issues local compensation commands to multiple sections, the synchronous adjustment of each independent traction drum will cause multi-point coupling disturbances in the entire tension chain, resulting in mutual restraint of the wire tension at each drawing die and mutual interference of the compensation actions, which in turn causes the diameter deviation of each drawing die to diverge or oscillate. Therefore, after detecting that multiple die-level diameter deviations exceed the tolerance simultaneously, the controller first calculates the absolute value of the die-level diameter deviation corresponding to each drawing die with the excess deviation, and establishes a compensation priority queue in descending order of the absolute value; the larger the absolute value, the more severe the diameter deviation of the drawing die, and the higher its contribution to the final diameter accuracy of the finished wire. The controller generates local compensation commands for each drawing die with the excess deviation in the order of the compensation priority queue and issues them one by one, rather than issuing them in batches simultaneously.

[0096] For example, in a production line containing five tandem drawing dies, the controller detects that the die-level diameter deviations of dies 2, 4, and 5 simultaneously exceed the corresponding local deviation thresholds; where the absolute value of the deviation for die 2 is 0.05 mm, for die 5 it is 0.04 mm, and for die 4 it is 0.03 mm. The controller sorts the dies by absolute value from largest to smallest, establishing a compensation priority queue as follows: die 2, then die 5, and then die 4. The controller first generates a local compensation command for die 2 and sends it to the independent traction drum in its downstream adjacent section; after subsequent steps confirm that the deviation of die 2 has converged to the corresponding deviation threshold range, it then generates and sends a local compensation command for die 5; finally, it performs the same operation for die 4. Through this sequential sending mechanism, multi-point simultaneous compensation is transformed into point-by-point sequential compensation, avoiding multi-point coupling oscillations of the entire line tension chain, and ensuring that each local compensation action takes effect independently under the premise of stable overall line tension.

[0097] S602: In the process of sequentially issuing commands, after each command is issued, the actual measured diameter of the wire at the wire drawing die exit that the current local compensation command is targeting is re-acquired, and it is confirmed that the die-level diameter deviation has converged to the corresponding local deviation threshold range before issuing the next local compensation command.

[0098] In some embodiments, due to the process lag between the adjustment of the traction speed and the change in the die exit diameter, after the local compensation command is issued, the speed of the independent traction drum is adjusted to the target traction speed, and the metal plastic flow of the wire in the die deformation zone re-establishes equilibrium, ultimately bringing the die exit diameter closer to the theoretical value. This process requires a certain response time. Therefore, after issuing a local compensation command for a certain die, the controller waits for a preset response time. The preset response time is pre-set based on the wire material, the length of the die deformation zone, and the wire travel speed, representing the time required for the traction speed adjustment to stabilize the die exit diameter. After the wait is completed, the controller re-acquires the measured diameter of the wire at the die exit measured by the laser diameter gauge and calculates the current die-level diameter deviation. When the absolute value of the die-level diameter deviation is less than or equal to the local deviation threshold corresponding to the current die, it is confirmed that the die-level diameter deviation has converged to the corresponding local deviation threshold range. Only after confirming that the deviation of the current die has converged does the controller issue a local compensation command to the next die according to the compensation priority queue.

[0099] For example, following the S601 example, after the controller issues a local compensation command to mold 2, it waits for a preset response time of 2 seconds (this time is estimated based on the current wire travel speed of 5m / s and the mold deformation zone length of 10m, ensuring that the wire completes at least one complete deformation zone update cycle). After the wait is over, the controller re-acquires the measured wire diameter at the exit of mold 2 as 0.498mm, the theoretical exit diameter as 0.50mm, and the current mold-level diameter deviation as -0.002mm. Its absolute value is less than the local deviation threshold of 0.03mm after dynamic adjustment of the mold, confirming convergence. Only then does the controller generate and issue a local compensation command for the next priority mold 5. If the absolute value of the deviation of mold 2 after re-acquisition is still greater than the local deviation threshold, the controller will not issue a command to mold 5 temporarily, prioritizing the stable convergence of the local compensation effect of mold 2, avoiding the superposition of compensation actions of multiple molds during the process lag period, which could lead to coupled oscillations and wire breakage risks in the entire tension chain.

[0100] Preferably, before adjusting the local traction speed of the section, the method further includes steps S211-S213.

[0101] S211: Obtain the current wire tension in the downstream adjacent section of the mold;

[0102] In some embodiments, the current filament tension refers to the axial tensile force borne by the filament in the downstream adjacent section of the die during the traction process. The tension detection device is positioned between the independent traction drum and the corresponding drawing die outlet in the downstream adjacent section of the die, and senses the filament tension in real time using a piezoelectric tension sensor or a strain gauge tension sensor. The tension detection device converts the sensed tension signal into an electrical signal and transmits it to the controller. The controller converts the electrical signal into the current filament tension according to a preset calibration coefficient of the tension detection device. The current filament tension reflects the tension state of this section before the local compensation command is issued.

[0103] For example, for a section immediately downstream of a drawing die, the electrical signal measured by the tension detection device is converted, and the controller obtains that the current wire tension is 120N.

[0104] S212: Calculate the adjusted predicted wire tension based on the target traction speed carried in the local compensation command;

[0105] In some embodiments, the predicted wire tension refers to the steady-state tensile force that the wire will reach in the downstream adjacent section of the die after the local traction speed adjustment is performed according to the target traction speed carried in the local compensation instruction. In the wire drawing process, wire tension is positively correlated with traction speed; when the traction speed increases, the rate of plastic deformation of the metal in the die deformation zone increases, the drawing resistance increases accordingly, and the wire tension rises accordingly. The controller multiplies the current wire tension by the speed ratio of the target traction speed to the current traction speed of the section to obtain the predicted wire tension. The speed ratio is the ratio of the target traction speed to the current traction speed.

[0106] For example, the current traction speed of the downstream adjacent section of a mold is 5.0 m / s, and the current wire tension is 120 N. The target traction speed carried by the local compensation command is 5.2 m / s, and the speed ratio is 1.04. The controller calculates the predicted wire tension as 120 N × 1.04 = 124.8 N.

[0107] S213: When the predicted filament tension exceeds the preset safe tension threshold, the target traction speed is corrected to the safe traction speed corresponding to the preset safe tension threshold, and the safe traction speed is used as the local traction speed of the section.

[0108] In some embodiments, the preset safety tension threshold is pre-set based on the tensile strength of the filament material, the theoretical cross-sectional area of ​​the filament in that section, and a process safety factor. The process safety factor is typically between 0.6 and 0.8 to ensure that the filament is in the elastic deformation zone during the drawing process, avoiding excessive plastic deformation or breakage. When the predicted filament tension is greater than the preset safety tension threshold, it indicates that adjusting according to the target traction speed will cause the tension in that section to be overloaded, posing a risk of filament breakage. At this time, the controller corrects the target traction speed to the safe traction speed. The safe traction speed is determined based on the ratio between the current filament tension and the preset safety tension threshold. Specifically, the controller multiplies the current traction speed by the ratio of the preset safety tension threshold to the current filament tension to obtain the safe traction speed. The controller replaces the target traction speed with the safe traction speed as the local traction speed for that section and generates a local compensation command carrying the safe traction speed, thereby constraining the filament tension within a safe range while ensuring that the diameter deviation compensation direction remains unchanged.

[0109] For example, the current traction speed of a downstream section of a mold is 5.0 m / s, the current wire tension is 120 N, the target traction speed carried by the local compensation command is 5.5 m / s, and the predicted wire tension is 132 N. The preset safe tension threshold is 130 N, and the predicted wire tension of 132 N exceeds this threshold. The controller calculates the safe traction speed as 5.0 m / s × (130 N / 120 N) = 5.42 m / s. The controller corrects the target traction speed from 5.5 m / s to 5.42 m / s, and uses 5.42 m / s as the local traction speed for this section to generate a local compensation command and send it to the independent traction drum. The measured diameter of the wire in this section still converges towards the theoretical outlet diameter, but the increase in traction speed is limited to ensure that the wire tension does not exceed the safe boundary of 130 N.

[0110] Preferably, the method further includes S701-S702.

[0111] S701: When the die-level diameter deviation of the corresponding wire drawing die is continuously within the corresponding local deviation threshold range within the preset monitoring period, and shows a monotonically increasing or monotonically decreasing trend, the pre-stored theoretical exit diameter is updated according to the statistical mean of the measured diameter of the wire obtained each time within the preset monitoring period.

[0112] In some embodiments, the preset monitoring period is set according to the typical progressive duration of die wear, such as continuous operation for 2 hours or the cumulative wire drawing length reaching a preset length threshold. Within the preset monitoring period, the controller periodically acquires the measured diameter of the wire at the die drawing exit and calculates the die-level diameter deviation. When the absolute value of the die-level diameter deviation calculated in each instance does not exceed the corresponding local deviation threshold, and the deviation values ​​show a monotonically increasing (i.e., the deviation value continuously increases positively) or monotonically decreasing (i.e., the deviation value continuously increases negatively) trend over time, it indicates that the die cavity has undergone systematic dimensional drift due to progressive wear, rather than occasional process disturbances. In this case, if the original pre-stored theoretical exit diameter remains unchanged, the controller will frequently trigger local compensation for this trend of wear deviation, causing the independent traction drum to repeatedly adjust and exacerbate the tension fluctuations of the entire production line.

[0113] Furthermore, the controller calculates the statistical mean of the measured diameter of the wire obtained in each of the preset monitoring cycles, i.e., the arithmetic mean of the measured diameter of the wire in each cycle, and replaces the pre-stored theoretical exit diameter with this statistical mean to complete the update of the theoretical exit diameter. After the update, the calculation benchmark of the mold-level diameter deviation matches the actual wear state of the mold, thereby suppressing frequent compensation actions caused by the mismatch between the theoretical value and the actual cavity size, and focusing the local deviation threshold and local compensation resources on real occasional process fluctuations.

[0114] For example, the pre-stored theoretical exit diameter of a certain wire drawing die is 0.50 mm, and the local deviation threshold is 0.03 mm. During a preset monitoring period of 2 consecutive hours, the controller acquires the measured diameter of the wire every 10 seconds. The calculated die-level diameter deviations are +0.01 mm, +0.012 mm, +0.015 mm…+0.025 mm, all within the local deviation threshold range and showing a monotonically increasing trend. The statistical average of the measured wire diameters during this period is 0.502 mm. Based on this, the controller updates the pre-stored theoretical exit diameter to 0.502 mm.

[0115] S702: Use the updated theoretical exit diameter as the benchmark for subsequent determination of mold-level diameter deviation.

[0116] In some embodiments, the controller writes the statistical mean into the parameter storage area of ​​the corresponding wire drawing die in the memory, replacing the original theoretical exit diameter of the die. From the update time, in subsequent step S200, the controller uses the updated theoretical exit diameter as the reference value for calculating the die-level diameter deviation of the die; that is, the difference between the measured diameter of the wire and the updated theoretical exit diameter is used as the die-level diameter deviation of the die. The updated theoretical exit diameter is stored in association with the historical wear record of the die, and an update timestamp is recorded.

[0117] In some embodiments, the theoretical exit diameter of each drawing die is maintained independently, and updating the theoretical exit diameter of a single die does not affect the reference parameters of other dies. Before each execution of step S200, the controller reads the currently valid theoretical exit diameter of each die from the memory to ensure that the calculation reference for the die-level diameter deviation matches the latest wear state of the corresponding die.

[0118] For example, following the S701 example, the controller writes 0.502mm into the memory, replacing the original 0.50mm. In subsequent operation, when the laser diameter gauge at the mold exit obtains a measured wire diameter of 0.501mm, the controller calculates the mold-level diameter deviation as -0.001mm based on 0.502mm. This deviation is within the local deviation threshold range, and no local compensation needs to be triggered. Thus, the updated theoretical exit diameter enables the controller to adaptively adapt to the trend of progressive mold wear, avoiding misjudging the wear trend as an occasional process deviation and frequently triggering local compensation commands.

[0119] Preferably, the method further includes S001-S003.

[0120] S001: A drawing liquid film thickness detection device is installed at the entrance of the corresponding drawing die to obtain the real-time drawing liquid film thickness.

[0121] In some embodiments, the wire drawing fluid film thickness detection device is disposed upstream of the inlet of the corresponding wire drawing die, located between the supply outlet of the wire drawing fluid supply mechanism and the die inlet, for online sensing of the thickness of the wire drawing fluid film adhering to the surface of the wire before entering the die. The wire drawing fluid film thickness detection device employs the eddy current coating thickness measurement principle, utilizing an eddy current sensor probe to emit an alternating electromagnetic field onto the wire surface. Since the wire drawing fluid is a non-conductive medium, while the wire is a metallic conductor, the effective distance between the eddy current sensor probe and the metal body of the wire includes the wire drawing fluid film thickness. The wire drawing fluid film thickness detection device calculates the equivalent distance between the probe and the metal body of the wire based on the impedance change sensed by the eddy current sensor probe, and after deducting the calibrated fixed geometric distance between the probe and the die inlet reference surface, obtains the real-time wire drawing fluid film thickness on one side of the wire surface. The real-time wire drawing fluid film thickness characterizes the amount of wire drawing fluid adhering to the wire surface under the current operating conditions.

[0122] For example, at the entrance of a drawing die, the fixed geometric distance between the eddy current sensor probe of the drawing fluid film thickness detection device and the die entrance reference surface is 2.00 mm; the currently sensed equivalent distance is 2.03 mm, then the real-time drawing fluid film thickness is 0.03 mm. The controller compares this real-time drawing fluid film thickness with a pre-stored drawing fluid film thickness calibration value to determine whether a drawing fluid supply adjustment command needs to be generated.

[0123] S002: When the deviation between the real-time drawing liquid film thickness and the calibrated value of the drawing liquid film thickness exceeds the liquid film deviation threshold, a drawing liquid supply adjustment command is generated and sent to the drawing liquid supply mechanism of the corresponding drawing die.

[0124] In some embodiments, the liquid film deviation threshold is preset based on the type of drawing fluid, the material of the wire, and the reduction ratio of the corresponding drawing die, representing the maximum allowable deviation of the drawing fluid film thickness from the calibrated value at the inlet of the drawing die. The controller calculates the absolute value of the difference between the real-time drawing fluid film thickness and the calibrated value of the drawing fluid film thickness to obtain the liquid film thickness deviation. When the liquid film thickness deviation exceeds the liquid film deviation threshold, it indicates that the current drawing fluid supply deviates from the steady-state condition. An excessively thick liquid film will lead to excessive lubrication and unstable metal flow in the die inlet area, while an excessively thin liquid film will lead to increased die wear and increased drawing resistance. Both of these will cause the die diameter to deviate from the theoretical value. At this time, the controller generates a drawing fluid supply adjustment command and sends it to the drawing fluid supply mechanism of the corresponding drawing die. The drawing fluid supply mechanism includes a frequency-controlled drawing fluid pump and a supply pipeline. The drawing fluid supply adjustment command carries a target supply pressure or target flow rate value. After receiving the command, the drawing fluid supply mechanism adjusts the speed of the drawing fluid pump to adjust the supply in the direction of compensating for the liquid film thickness deviation.

[0125] For example, the calibrated thickness of the drawing liquid film of a certain drawing die is 0.01 mm, and the liquid film deviation threshold is 0.005 mm. The real-time drawing liquid film thickness obtained in step S001 is 0.016 mm, and the liquid film thickness deviation is 0.006 mm, exceeding the liquid film deviation threshold. The controller generates a drawing liquid supply adjustment command, which carries a target supply pressure that is 10% lower than the current value, and sends it to the drawing liquid supply mechanism of the die. The drawing liquid supply mechanism reduces the speed of the drawing liquid pump, reduces the drawing liquid supply, and causes the real-time drawing liquid film thickness on the surface of the subsequent wire to converge to 0.01 mm, thereby eliminating the drawing process disturbance caused by excessive liquid film thickness.

[0126] S003: After the drawing fluid supply mechanism executes the drawing fluid supply amount adjustment command, the original optical diameter at the drawing die outlet is re-acquired, and the fluid film thickness is corrected according to the pre-stored drawing fluid film thickness calibration value to obtain the actual diameter of the wire material, so as to determine the die-level diameter deviation.

[0127] In some embodiments, since the liquid film thickness at the drawing die inlet requires a certain response time to re-establish a steady state after the drawing fluid supply is adjusted, and there is also a process lag in the drawing deformation of the wire from the drawing die inlet to the outlet, the controller waits for a preset liquid film response time after the drawing fluid supply mechanism executes the drawing fluid supply adjustment command. The preset liquid film response time is preset based on the flow diffusion characteristics of the drawing fluid in the drawing die inlet area and the residence time of the wire in the drawing die deformation area. After the wait is completed, the controller obtains the original optical diameter of the wire surface when the drawing fluid film is attached using the laser diameter measuring instrument at the drawing die outlet, and corrects the liquid film thickness according to the pre-stored drawing fluid film thickness calibration value to obtain the re-obtained measured diameter of the wire. The controller compares the re-obtained measured diameter of the wire with the pre-stored theoretical outlet diameter and calculates the die-level diameter deviation to determine whether the drawing fluid supply adjustment has brought the diameter deviation of the die to within the corresponding local deviation threshold range.

[0128] For example, for a certain wire drawing die, the wire drawing fluid supply mechanism reduces the supply pressure from 0.3 MPa to 0.27 MPa to compensate for excessive fluid film thickness. Since the wire drawing fluid needs to redistribute along the wire surface and establish a stable fluid film in the die inlet area, this stable fluid film establishment process takes approximately 2.5 seconds due to the influence of the wire drawing fluid's dynamic viscosity (approximately 0.05 Pa·s) and the wire surface tension. Simultaneously, the wire travels through the die's deformation and sizing zones (total length approximately 20 mm) at a speed of 5 m / s, with a residence time of approximately 4 milliseconds. The controller sets the preset fluid film response time to 3 seconds, which is the sum of the fluid film stable establishment time and the wire residence time, rounded up to the nearest second. This ensures that the wire drawing fluid film is sufficiently stable in the die inlet area, and that the wire that has undergone drawing deformation has been completely replaced by a new fluid film state as it passes through the die.

[0129] For example, after the drawing fluid supply mechanism executes the adjustment command to reduce the supply pressure, the controller waits for a preset liquid film response time of 3 seconds. The laser diameter gauge measures the original optical diameter at the die exit as 0.512 mm, and the pre-stored drawing fluid film thickness calibration value is 0.01 mm. After liquid film thickness correction, the actual measured diameter of the wire is 0.492 mm. The theoretical exit diameter of the die is 0.50 mm, so the redefined die-level diameter deviation is -0.008 mm. Its absolute value is less than the corresponding local deviation threshold of 0.03 mm, indicating that the adjustment of the drawing fluid supply has brought the diameter deviation to converge, and there is no need to trigger local traction speed compensation again. If the die-level diameter deviation still exceeds the local deviation threshold, the controller enters step S200 and the subsequent local compensation process.

[0130] Preferably, the present invention also provides a closed-loop control system for the continuous wire drawing diameter of solder wire, the system comprising:

[0131] Multiple wire drawing dies arranged in series;

[0132] Multiple laser diameter measuring instruments are respectively installed at the exit of each of the wire drawing dies;

[0133] Multiple independent traction drums are respectively configured in the downstream adjacent section of each wire drawing die, serving as local actuators;

[0134] Multiple tension detection devices are respectively installed in the downstream adjacent section of each of the wire drawing dies;

[0135] Multiple wire drawing liquid film thickness detection devices are respectively installed at the entrance of each of the wire drawing dies;

[0136] Multiple drawing fluid supply mechanisms are respectively configured for each of the drawing dies;

[0137] Memory;

[0138] The controller is communicatively connected to the laser diameter measuring instrument, the independent traction drum, the tension detection device, the wire drawing liquid film thickness detection device, the wire drawing liquid supply mechanism, and the memory, respectively, so that the system executes the closed-loop control method for continuous solder wire drawing diameter as described above.

[0139] The system includes multiple wire drawing dies arranged in series to progressively reduce the diameter of coarse solder bars to form wire; multiple laser diameter gauges, each positioned at the exit of one of the dies, to acquire real-time data on the surface diameter of the wire at each die exit; multiple independent traction drums, each positioned downstream of one of the dies and acting as local actuators, to receive local compensation commands and adjust the local traction speed of the corresponding section; multiple tension detection devices, each positioned downstream of one of the dies, to acquire real-time data on the current wire tension in the corresponding section; and multiple wire drawing liquid film thickness detection devices, each positioned at the entrance of one of the dies. The system includes a real-time acquisition point for the real-time thickness of the drawing fluid film at the corresponding mold inlet; multiple drawing fluid supply mechanisms, each corresponding to one of the drawing dies, for receiving drawing fluid supply adjustment commands and adjusting the drawing fluid supply to the corresponding die; a memory for pre-storing the theoretical outlet diameter, local deviation threshold, historical wear records, and drawing fluid film thickness calibration values ​​for each drawing die; and a controller, communicatively connected to the laser diameter measuring instrument, the independent traction drum, the tension detection device, the drawing fluid film thickness detection device, the drawing fluid supply mechanism, and the memory, for coordinating the execution of the solder wire continuous drawing diameter closed-loop control method as described above.

[0140] Therefore, the embodiments should be considered as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the application are intended to be included within the invention.

[0141] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A closed-loop control method for the continuous wire drawing diameter of solder wire, characterized in that, Includes the following steps: Obtain the measured diameter of the wire at the exit of each drawing die; Based on the measured diameter of each wire and the pre-stored theoretical exit diameter, the diameter deviation of each mold stage is determined; when the diameter deviation of any mold stage exceeds the corresponding local deviation threshold, a local compensation instruction is generated. The local compensation command is sent to the local actuator in the downstream adjacent section of the corresponding wire drawing die to adjust the local traction speed of that section so that the measured diameter of the wire passing through the wire drawing die is close to the theoretical exit diameter. The downstream section of the wire drawing die is equipped with an independent traction drum, and the adjustment of the local traction speed is constrained by the tension overload protection of the adjacent section; the local deviation threshold is preset according to the historical wear record of the corresponding wire drawing die and the calibrated value of the wire drawing liquid film thickness.

2. The closed-loop control method for continuous solder wire drawing diameter according to claim 1, characterized in that, The process of obtaining the measured diameter of the wire at the exit of each drawing die includes: A laser diameter measuring instrument is installed at the exit of each drawing die to obtain the original optical diameter of the wire when the drawing liquid film is attached to the surface of the wire. Based on the original optical diameter and the pre-stored drawing liquid film thickness calibration value, the original optical diameter is corrected for liquid film thickness to obtain the actual measured diameter of the wire. The thickness calibration value of the drawing fluid film is obtained in advance based on the drawing fluid supply pressure and wire travel speed of the corresponding drawing die.

3. The closed-loop control method for continuous solder wire drawing diameter according to claim 1, characterized in that, The generation of local compensation instructions includes: Obtain the direction and absolute value of the mold-level diameter deviation; When the mold-level diameter deviation indicates that the measured diameter of the wire is greater than the theoretical exit diameter, the adjustment direction of the local traction speed is determined to be an increase in speed. When the mold-level diameter deviation indicates that the measured diameter of the wire is less than the theoretical exit diameter, the adjustment direction of the local traction speed is determined to be a reduction. The adjustment range of the local traction speed is determined based on the ratio of the absolute value to the corresponding local deviation threshold. The local compensation command is generated based on the adjustment direction and the adjustment amplitude, and the local compensation command carries the target traction speed.

4. The closed-loop control method for continuous solder wire drawing diameter according to claim 1, characterized in that, The adjustment of the local traction speed is constrained by the tension overload protection of adjacent sections, including: Obtain the current traction speed of the downstream adjacent section of the corresponding wire drawing die, and the current traction speed of the adjacent upstream section; After adjusting the local traction speed of the downstream adjacent section according to the local compensation command and the current traction speed of the downstream adjacent section, the theoretical following speed of the adjacent upstream section is calculated based on the second flow conservation and used as a reference benchmark for the tension overload protection constraint. When the deviation between the theoretical following speed and the current traction speed of the adjacent upstream section exceeds a preset speed synchronization threshold, a following speed adjustment command is issued to the independent traction drum of the adjacent upstream section to make the traction speed of the adjacent upstream section approach the theoretical following speed.

5. The closed-loop control method for continuous solder wire drawing diameter according to claim 1, characterized in that, The method further includes: Get the cumulative wire drawing length of the corresponding wire drawing die since the last maintenance; The wear trend level of the die is determined based on the cumulative wire drawing length and the wear rate in the historical wear record; The local deviation threshold is dynamically adjusted based on the mold wear trend level. The higher the wear trend level, the tighter the local deviation threshold becomes towards the allowable upper limit of the mold-level diameter deviation.

6. The closed-loop control method for continuous solder wire drawing diameter according to claim 1, characterized in that, When multiple mold-level diameter deviations simultaneously exceed the corresponding local deviation threshold, the method further includes: According to the absolute values ​​of the diameter deviations of each mold level in descending order, multiple local compensation commands are generated and issued sequentially; During the sequential issuance process, after each issuance is completed, the measured diameter of the wire at the wire drawing die exit that is targeted by the currently issued local compensation command is re-acquired, and it is confirmed that the diameter deviation of the die level has converged to the corresponding local deviation threshold range before the next local compensation command is issued.

7. The closed-loop control method for continuous solder wire drawing diameter according to claim 3, characterized in that, Before adjusting the local traction speed of the section, the method further includes: Obtain the current wire tension in the downstream adjacent section of the mold; Calculate the adjusted predicted wire tension based on the target traction speed carried in the local compensation command; When the predicted filament tension exceeds the preset safe tension threshold, the target traction speed is corrected to the safe traction speed corresponding to the preset safe tension threshold, and the safe traction speed is used as the local traction speed of the section.

8. The closed-loop control method for continuous solder wire drawing diameter according to claim 1, characterized in that, The method further includes: When the die-level diameter deviation of the corresponding wire drawing die remains within the corresponding local deviation threshold range within the preset monitoring period and shows a monotonically increasing or monotonically decreasing trend, the pre-stored theoretical exit diameter is updated according to the statistical mean of the measured diameter of the wire obtained each time within the preset monitoring period. The updated theoretical exit diameter will be used as the benchmark for determining the mold-level diameter deviation.

9. The closed-loop control method for continuous solder wire drawing diameter according to claim 1, characterized in that, The method further includes: A drawing liquid film thickness detection device is installed at the entrance of the corresponding drawing die to obtain the real-time drawing liquid film thickness. When the deviation between the real-time drawing liquid film thickness and the calibrated value of the drawing liquid film thickness exceeds the liquid film deviation threshold, a drawing liquid supply adjustment command is generated and sent to the drawing liquid supply mechanism of the corresponding drawing die. After the drawing fluid supply mechanism executes the drawing fluid supply amount adjustment command, the original optical diameter at the drawing die outlet is re-acquired, and the fluid film thickness is corrected according to the pre-stored drawing fluid film thickness calibration value to obtain the measured diameter of the wire, so as to determine the die-level diameter deviation.

10. A closed-loop control system for the continuous wire drawing diameter of solder wire, characterized in that, The system includes: Multiple wire drawing dies arranged in series; Multiple laser diameter measuring instruments are respectively installed at the exit of each of the wire drawing dies; Multiple independent traction drums are respectively configured in the downstream adjacent section of each wire drawing die, serving as local actuators; Multiple tension detection devices are respectively installed in the downstream adjacent section of each of the wire drawing dies; Multiple wire drawing liquid film thickness detection devices are respectively installed at the entrance of each of the wire drawing dies; Multiple drawing fluid supply mechanisms are respectively configured for each of the drawing dies; Memory; The controller is communicatively connected to the laser diameter measuring instrument, the independent traction drum, the tension detection device, the wire drawing liquid film thickness detection device, the wire drawing liquid supply mechanism, and the memory, respectively, so that the system executes the closed-loop control method for continuous wire drawing diameter of solder wire as described in any one of claims 1-9.

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