A protective gas flow mixing controller for a welding apparatus

Abstract

The present application belongs to the technical field of welding equipment, and particularly relates to a protective gas flow mixing controller for welding equipment, which comprises a gas fusion unit, an audio sensing unit, a droplet transition frequency extraction module, a welding current acquisition unit, a target frequency generation submodule and a mixing ratio optimization controller. The audio sensing unit on the welding torch is used to acquire an audio signal, and a droplet transition frequency is extracted in real time. A target transition frequency is determined according to the welding current. A control direction and an adaptive gain are automatically identified through disturbance exploration. In a non-exploration state, an opening degree adjustment amount is output based on the control direction gain. A second electronic proportional valve is controlled according to the opening degree adjustment amount, and the protective gas mixing ratio is dynamically optimized. The present application can adapt to welding working condition changes, stabilize droplet transition, reduce spatter and improve welding quality.

Description

Technical Field

[0001] This invention belongs to the field of welding equipment technology, and specifically relates to a protective gas flow mixing controller for welding equipment. Background Technology

[0002] In gas shielded welding, the composition ratio of the shielding gas (e.g., the mixture ratio of argon and carbon dioxide) directly affects the arc morphology, droplet transfer frequency, spatter rate, and weld formation quality. Existing technologies mainly employ two methods to adjust the shielding gas mixture ratio: one uses a mechanical proportional valve for open-loop control, resulting in a fixed mixture ratio that cannot be dynamically adjusted according to changes in welding conditions; the other uses a flow sensor-based closed-loop control, aiming to maintain a preset mixture ratio. This control relies on the internal flow rate of the gas path, rather than the state signals of the welding process itself, and therefore cannot directly respond to changes in arc behavior.

[0003] During welding, changes in wire extension, workpiece heat dissipation, or plate gaps can cause the droplet transition frequency to drift, even with a constant mixing ratio, leading to increased spatter. The correlation (i.e., adjustment direction) between changes in the mixing ratio and the droplet transition frequency may differ depending on the welding wire material, welding current range, and shielding gas type. Current technologies for adaptive mixing ratio adjustment typically require prior calibration of this correlation through numerous process experiments, or manual input of the adjustment direction by the operator based on experience. This not only increases the barrier to entry and debugging costs but also fails to adapt to sudden changes in operating conditions during welding.

[0004] Therefore, there is an urgent need for a protective gas flow mixing controller for welding equipment to solve the technical problems of uncertain direction and poor adaptability in the existing technology. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the present invention provides a protective gas flow mixing controller for welding equipment to solve the problems in the background art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A protective gas flow mixing controller for welding equipment includes a gas fusion unit comprising a first electronic proportional valve and a second electronic proportional valve; An audio sensing unit is installed on the welding torch and outputs digital audio signals; The droplet transition frequency extraction module is connected to the audio sensing unit and outputs the real-time droplet transition frequency and corresponding timestamp for each droplet transition cycle. Welding current acquisition unit, outputs welding current; The target frequency generation submodule is connected to the welding current acquisition unit and outputs the target transition frequency corresponding to the welding current. A mixing ratio optimization controller is connected to a droplet transition frequency extraction module and a target frequency generation submodule. The mixing ratio optimization controller includes an encoded perturbation trial submodule and a deviation calculation and control law submodule. The coded perturbation probing submodule includes: a perturbation application unit, which, after receiving a trigger signal, outputs a short pulse to the second electronic proportional valve at a fixed time delay after each droplet transition event occurs within multiple consecutive droplet transition cycles. The period during which the perturbation application unit outputs the short pulse is a probing state. The direction determination unit calculates a baseline average value by averaging the droplet transition frequencies over multiple consecutive droplet transition cycles before the short-time pulse is applied; it then calculates a post-average value by averaging the droplet transition frequencies over multiple consecutive droplet transition cycles after the short-time pulse is applied, and uses the difference between the post-average value and the baseline average value as the average value change; the control direction gain is determined based on the product of the average value change and the current frequency deviation, where the current frequency deviation is the difference between the baseline average value and the target transition frequency. The deviation calculation and control law submodule, in the non-trial state, outputs an opening adjustment amount based on the control direction gain, and controls the second electronic proportional valve according to the opening adjustment amount to optimize the protective gas mixing ratio.

[0007] Furthermore, the duration of the short pulse is less than the duration of a droplet transition cycle, and the sum of the fixed time delay and the duration of the short pulse is less than the duration of a droplet transition cycle.

[0008] Furthermore, the coded perturbation probe submodule also includes a benchmark statistics unit, which, after receiving the trigger signal, collects the real-time droplet transition frequency of multiple droplet transition cycles, calculates the benchmark average value and standard deviation, and when the standard deviation is lower than the stability threshold, the perturbation application unit outputs the short-time pulse.

[0009] Furthermore, the determination of the control direction gain is specifically as follows: if the product of the average value change and the current frequency deviation is negative, then the control direction gain is positive; if the product is positive, then the control direction gain is negative.

[0010] Furthermore, the encoded perturbation probing submodule also includes an adaptive amplitude adjustment unit. When the absolute value of the change in the average value is less than the preset minimum detectable frequency change threshold, the amplitude of the short-time pulse is increased in subsequent probing. If the absolute value of the frequency difference between two consecutive adjacent droplet transition cycles exceeds the preset jump threshold during the application of the short-time pulse, the current probing is terminated and the amplitude of the short-time pulse is reduced to the amplitude used in the previous probing.

[0011] Furthermore, the coded perturbation probe submodule also includes a gain calculation unit, which determines the adaptive proportional gain according to the following formula: in, For adaptive proportional gain, As the reference proportional gain, The average change The reference response amplitude is used; the proportional gain in the deviation calculation and control law submodule adopts an adaptive proportional gain.

[0012] Furthermore, the predetermined control law in the deviation calculation and control law submodule is an incremental PID control law, and the opening adjustment amount conforms to: in, This is the opening adjustment amount. To control the cycle number, This represents the current frequency deviation. , For control parameters, To control directional gain, For the first Frequency deviation per cycle, For the first Frequency deviation per cycle.

[0013] Furthermore, the droplet transition frequency extraction module includes an envelope detection unit and a smoothing filter unit; the smoothing filter unit performs an exponentially weighted moving average on the real-time droplet transition frequency; and the envelope detection unit uses Hilbert transform to extract the instantaneous envelope.

[0014] Furthermore, the audio sensing unit includes a microphone, a preamplifier, an anti-aliasing filter, and an analog-to-digital converter; the welding current acquisition unit includes a current sensor and an analog-to-digital converter.

[0015] Furthermore, the coded disturbance probing submodule also includes a probing trigger judgment unit, which outputs a trigger signal when any of the following conditions are met: when the system is powered on or when the arc is restarted after welding stops, the welding current is detected to jump from below the first threshold to above the second threshold; the change in welding current within the time window exceeds the percentage threshold; or an external manual trigger signal is received.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention applies a synchronous short-time pulse during the droplet transition period through an encoded perturbation probe submodule. The direction determination unit automatically determines the control direction gain based on the sign of the product of the frequency change before and after the pulse and the current frequency deviation. This eliminates the need for pre-calibrating the mapping relationship between the welding wire material and the shielding gas, and also eliminates the need for the operator to manually input the adjustment direction. This solves the technical problem of uncertain direction under different welding wire and current ranges in the prior art. 2. This invention uses the droplet transition frequency as a feedback variable. The target frequency generation module outputs the target frequency corresponding to the welding current in real time. The deviation calculation and control law submodule generates the opening adjustment amount based on the control direction gain and adaptive proportional gain in the non-trial state. It performs closed-loop compensation for frequency drift caused by changes in dry extension and fluctuations in heat dissipation conditions, ensuring that the mixing ratio always matches the actual process requirements and eliminating the deviation between the preset parameters and the actual working conditions. 3. This invention suppresses random fluctuations in droplet transition through multi-pulse cumulative response, significantly improving the signal-to-noise ratio for direction determination; adaptive amplitude adjustment and mode transition protection mechanisms ensure that disturbances do not affect welding quality. The system is applicable to various materials such as carbon steel, stainless steel, and aluminum alloys, and different transition modes such as short circuits and jetting, automatically maintaining an ideal state of low spatter and stable arc under various working conditions. Attached Figure Description

[0017] Figure 1 This is a system architecture diagram of the controller; Detailed Implementation To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0018] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0019] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0020] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Example 1: like Figure 1 As shown, the present invention provides a protective gas flow mixing controller for welding equipment, comprising a gas fusion unit including a first electronic proportional valve and a second electronic proportional valve, used to regulate the flow rates of a first protective gas component (such as argon) and a second protective gas component (such as carbon dioxide), respectively. It also includes a valve drive module, which is connected to a deviation calculation and control law submodule and the second electronic proportional valve.

[0022] The audio sensing unit, mounted on the welding torch, outputs digital audio signals. It is used to acquire audio signals generated by the welding arc and molten droplet transfer, and outputs digital audio signals. Specifically, this unit includes a microphone, a preamplifier, an anti-aliasing filter, and an analog-to-digital converter, all covered by a spatter-proof protective cover.

[0023] The microphone is mounted inside the welding torch handle, with its sensitive side facing the welding arc area and covered by a spatter-proof protective cover. The preamplifier is a low-noise instrumentation amplifier with a gain of 40dB. The anti-aliasing filter is an active low-pass filter with a cutoff frequency of 5kHz. The analog-to-digital converter is a Σ-Δ analog-to-digital converter with a sampling rate of 16kHz, outputting a digital audio signal.

[0024] In actual welding environments, there is mechanical noise from spatter impacting the welding torch, electromagnetic interference, and electrical noise from surrounding equipment. An external spatter shield prevents large spatter particles from directly impacting the microphone diaphragm; an active low-pass filter filters out high-frequency electromagnetic interference above the Nyquist frequency, preventing spectral aliasing after sampling. The digital audio signal, after analog-to-digital conversion, is sent to the droplet transition frequency extraction module. The digital IIR bandpass filter in this module further removes low-frequency noise (<80Hz) generated by mechanical vibration and residual high-frequency interference (>2kHz), ensuring that the signal-to-noise ratio within the characteristic frequency band (80Hz-2kHz) generated by the droplet transition event remains within a detectable range.

[0025] The droplet transition frequency extraction module, connected to the audio sensing unit, outputs the real-time droplet transition frequency and corresponding timestamp for each droplet transition cycle. This module includes an envelope detection unit and a smoothing filter unit. The smoothing filter unit performs an exponentially weighted moving average on the real-time droplet transition frequency. The envelope detection unit uses a Hilbert transform to extract the instantaneous envelope. The module extracts the droplet transition frequency from the digital audio signal in real time and outputs the real-time frequency value and timestamp of the droplet transition event for each droplet transition cycle. This module includes a digital IIR bandpass filter, a Hilbert transform unit, an adaptive threshold comparator (sliding window root mean square), a pulse interval timing unit, and an exponentially weighted moving average smoother.

[0026] Specifically, the digital IIR bandpass filter has a passband of 80Hz-2kHz and a 6th order, filtering out low-frequency arc noise and high-frequency interference. The passband range is selected based on the fact that the typical range of droplet transfer frequency under different welding currents is 80Hz (short-circuit transfer) to 1200Hz (jet transfer), and the cutoff frequency above 2kHz can effectively filter out high-frequency electrical interference while retaining the main frequency energy of the transfer event.

[0027] The envelope detector unit performs a Hilbert transform on the filtered signal to extract the instantaneous envelope. The Hilbert transform is a classic method for obtaining the signal envelope, which is sensitive to transient impact signals and is suitable for detecting droplet transition events.

[0028] The adaptive threshold comparator uses a sliding window to calculate the root mean square of the envelope as a dynamic threshold. The window length covers at least one expected droplet transition cycle. The sampling points are selected to ensure that the window covers at least one expected droplet transition cycle. When the envelope exceeds the dynamic threshold, it is determined as the start time of a droplet transition event. The number of sampling points between two consecutive start times is recorded, and the real-time droplet transition frequency is calculated. An exponentially weighted moving average is used to smooth the real-time frequency with a smoothing factor of 0.15 and a control period of 50ms. The smoothing factor is selected so that the filter's response time to frequency abrupt changes is approximately three control periods, which can effectively filter out random fluctuations in droplet transition and track process changes (such as dry stretching drift) in a timely manner. The above signal processing methods (IIR filtering, Hilbert transform, sliding window root mean square, EWMA) are all conventional techniques in the field of digital signal processing.

[0029] The welding current acquisition unit outputs the welding current; the welding current acquisition unit includes a current sensor and an analog-to-digital converter, with a sampling rate of 1kHz, and outputs the average value for each control cycle.

[0030] Specifically, the current sensor is installed on the output bus of the welding power supply. The output analog voltage is linearly related to the welding current. After low-pass filtering, it is sampled by an analog-to-digital converter with a sampling rate of 1kHz. The arithmetic mean of 50 sampling points is taken in each control cycle (50ms) to obtain the average welding current of that cycle.

[0031] The selection of 50 sampling points is based on the fact that the 50ms time window is synchronized with the control cycle of the droplet transition frequency extraction module, and the 50-point average can effectively smooth out high-frequency noise above 20Hz (the low-pass cutoff frequency is about 10Hz), while retaining the low-frequency trend reflecting process changes. If the window is too short (e.g., 30 points), the smoothing will be insufficient; if it is too long (e.g., 100 points), the response will be lagging. The selection of current sensors and signal conditioning are existing technologies. This invention only provides the sampling rate, window duration, and average number of points required to achieve the purpose of this invention, which can be appropriately adjusted according to the output characteristics of the welding power supply.

[0032] The mixing ratio optimization controller is connected to the droplet transition frequency extraction module and the target frequency generation submodule. The mixing ratio optimization controller includes an encoded perturbation trial submodule and a deviation calculation and control law submodule. The target frequency generation submodule is connected to the welding current acquisition unit and outputs the target transition frequency corresponding to the welding current; it uses piecewise linear mapping for storage.

[0033] Specifically, this submodule uses the target transition frequency corresponding to the current welding current output as the given value for the deviation calculation and control law submodule. The mapping relationship is established and updated as follows: For calibrated operating conditions: For welding wire materials that have been pre-calibrated through process tests (such as carbon steel ER70S-6, stainless steel 308L, etc.), a piecewise linear interpolation method is used to construct the mapping relationship between welding current and target transition frequency. Specifically, several discrete points are calibrated in different current ranges (such as the short-circuit transition region and the droplet transition region). It is stored in non-volatile memory. During runtime, the current target transition frequency is calculated using a linear interpolation formula based on the real-time welding current range. in, Corresponding to the target transition frequency of the welding current, The welding current at the current moment. No. The average welding current collected within each control cycle No. The average welding current collected within each control cycle No. The target transition frequency within each control cycle No. The target transition frequency within each control cycle.

[0034] Uncalibrated operating condition: When the system is used for the first time or after changing the welding wire / shielding gas, there is no pre-calibrated mapping table inside. In this case, a default mapping plus adaptive correction strategy is adopted: An initial linear mapping relationship is set according to the welding process type (short-circuit transfer or droplet transfer): in, , Let be the initial coefficients of the mapping function. For processes where short-circuit transition is dominant, take . , For processes where droplet transfer is dominant, take , The initial values ​​are set based on statistical data of common welding wires to ensure that the system can start stably even without calibration.

[0035] After the system completes at least one micro-disturbance test and enters steady-state closed-loop regulation, the controller continuously collects data within the stable welding current range. The specific judgment criteria are: the welding current change rate is less than 5% and the duration exceeds 3 seconds, while the absolute value of the controller's output opening adjustment is less than 0.5% (i.e., the system is in a quasi-steady state with no significant adjustment). Each time the number of accumulated valid data points reaches... The group, i.e., performs a single least-squares linear fit, updates the coefficients of the mapping function: in, , The coefficients of the mapping function, For the first The real-time droplet transition frequency of the second sample is derived from the droplet transition frequency extraction module. It is the first The real-time welding current value obtained from the second sampling. To determine the number of data points used for least-squares fitting, this embodiment takes... The updated coefficients are stored in non-volatile memory, allowing the mapping relationship to gradually approximate the true characteristics of that specific welding wire / shielding gas.

[0036] If the system detects multiple dispersed clusters in the welding current distribution during long-term operation (e.g., a large number of data points near 80A, 150A, and 220A), it automatically divides the current operating range into multiple sub-intervals and performs the aforementioned linear fitting on each sub-interval, forming a piecewise linear mapping. This mechanism continuously improves the mapping accuracy as the usage frequency increases.

[0037] The coded perturbation probe submodule includes: The trigger judgment unit outputs a trigger signal when any of the following conditions are met: When the system is powered on or when the arc is restarted after welding has stopped, the welding current is detected to jump from below the first threshold (e.g., 20A) to above the second current threshold (e.g., 50A). Within a preset time window (e.g., 1 second), the change in welding current exceeds a preset percentage (e.g., 30%). Receives external manual trigger signals, such as button presses or communication commands.

[0038] The first current threshold (20A) and the second current threshold (50A) given in the above example are used to distinguish between the standby / arc-starting preparation state and the arc-started state of the welding machine. 20A is typically much lower than the minimum current required for stable droplet transfer (stable transfer of carbon steel GMAW generally requires above 80A), which avoids premature triggering during the initial current ramp-up phase of arc ignition; 50A indicates that arc ignition has occurred, but the fully stable operating zone has not yet been reached, allowing time for the system to stabilize. In practical applications, those skilled in the art can routinely adjust these two thresholds according to different welding wire materials (such as aluminum alloys, stainless steel), welding wire diameters (such as 0.8mm, 1.2mm, 1.6mm), and welding power source characteristics.

[0039] The time window is used to determine continuous current changes. A 1-second window can capture trend changes caused by wire feed fluctuations and bevel variations, while avoiding false triggering caused by high-frequency current fluctuations (usually with a period of less than 0.1 seconds) in the droplet transfer process itself. The 30% change threshold is significantly higher than the range of current changes caused by random fluctuations in normal welding (usually 5%-10%). When the current change exceeds 30% within 1 second, it indicates a significant change in operating conditions, such as a large change in wire extension, a sudden change in heat dissipation conditions, or a significant increase or decrease in the gap between plates. In this case, the original control direction gain needs to be redefined. For processes with large current fluctuations, such as short-circuit transfer, the threshold can be relaxed accordingly, such as 50% / 1 second, or combined with other characteristics (such as arc voltage) for comprehensive judgment. For high-speed welding or robotic welding, the time window can be appropriately reduced or the amplitude threshold can be lowered to improve response sensitivity.

[0040] It should be clarified that the specific values ​​mentioned above are merely examples to help understand the technical solution of this invention and are not intended to limit the scope of protection of this invention. In practical applications, those skilled in the art can routinely adjust and optimize the above thresholds based on factors such as different welding wire materials (e.g., aluminum alloy, stainless steel), welding wire diameters (e.g., 0.8mm, 1.2mm, 1.6mm), welding processes (short-circuit transfer, pulse welding, double-pulse welding), and specific welding equipment characteristics (e.g., power supply dynamic response, wire feeding system stability) to adapt to the arc initiation characteristics and condition change detection requirements under specific welding conditions.

[0041] The baseline statistics unit, upon receiving the trigger signal, acquires the real-time droplet transition frequency of multiple droplet transition cycles, calculates the baseline average value and standard deviation, and when the standard deviation is lower than the stability threshold, the disturbance application unit outputs a short-time pulse. The duration of the short-time pulse is less than the duration of one droplet transition cycle, and the sum of the fixed time delay and the duration of the short-time pulse is less than the duration of one droplet transition cycle.

[0042] Specifically, after receiving the trigger signal, continuous data acquisition is performed. indivual( The real-time frequency value of the droplet transition period is used to calculate the baseline average value. and standard deviation Only when the standard deviation The disturbance application unit is only allowed to output a short-time pulse when the frequency is below a preset stability threshold (e.g., 3Hz).

[0043] The droplet transfer frequency itself exhibits random fluctuations of 2-4 Hz. When the standard deviation exceeds 3 Hz, the welding process itself becomes unstable, due to factors such as uneven wire feeding or arc vibration. Applying disturbances at this point may lead to misjudgments, therefore, it is required that... To ensure the effectiveness and repeatability of the trial.

[0044] After receiving the trigger signal, the disturbance application unit outputs a short pulse to the second electronic proportional valve at a fixed time delay after each droplet transition event during multiple consecutive droplet transition cycles. The period during which the disturbance application unit outputs the short pulse is a trial state. Continuous after receiving the trigger signal Within each droplet transition cycle, at a fixed time delay after each droplet transition event, a short pulse is output to the second electronic proportional valve, with a duration of [duration missing]. This causes a small increment in the flow rate of the second protective gas component. Fixed time delay Duration of short pulse The sum of these values ​​is less than the duration of a single droplet transition cycle, ensuring that the entire disturbance window is completely within a single droplet transition cycle.

[0045] Fixed time delay Duration of short pulse The requirement is that within approximately 2-3 ms after the droplet transition event, the new droplet is in its early growth stage, and the arc force does not change drastically. Applying a short pulse during this stage has virtually no impact on the current transition process, but it can have a cumulative effect on the initial conditions of subsequent droplets. This embodiment selects... =1ms, the 1ms pulse width is less than 10% of the transition period, which is easy to implement.

[0046] After the droplet transfer event occurs, the droplet detaches from the welding wire tip and enters the molten pool, the arc is re-established, and the growth of the next droplet begins. This process typically accounts for the first 10%-30% of the entire transfer cycle. This embodiment selects... The significance lies in the fact that, in the initial stage after the droplet transition (within approximately 2 ms), the next droplet is in its early growth stage. At this time, short-term modulation of the arc force or protective gas flow rate has virtually no impact on the current transition process, but it has a cumulative effect on the initial conditions of subsequent transitions. After the accumulation of multiple pulses, this minute modulation can have an observable impact on the average droplet transition frequency. This delay value needs to be adapted within the range of 2-5 ms.

[0047] Droplet transition period If the value is too small, such as less than 5, it will lead to insufficient statistical significance, making it difficult to extract an effective response from random fluctuations; If the value is too large, such as greater than 10, the trial period should be extended, which may cause the optimal time for adjusting process parameters to be missed. With a set droplet transition period of 5-10, the probe can be completed in about 1 second, balancing the reliability of direction determination with the real-time nature of system response.

[0048] The adaptive amplitude adjustment unit adjusts the amplitude when the absolute value of the change in the average value is less than a preset minimum detectable frequency change threshold. This indicates that the current disturbance amplitude is too small and the system response is insufficient, so the pulse amplitude will be increased in the next attempt; this embodiment Based on experimental statistics, the natural fluctuation range of the droplet transition frequency during stable welding is approximately ±1Hz. Only when it exceeds this value is it considered to be an effective response caused by disturbance.

[0049] During the short-time pulse application, the absolute value of the frequency difference between two consecutive adjacent droplet transition cycles exceeds a preset transition threshold. If the disturbance amplitude is too large, indicating an undesirable jump in the transition mode (such as a sudden transition from short-circuit transition to droplet transition), the current probe is immediately terminated, and the pulse amplitude is reduced to the amplitude used in the previous probe. This embodiment... The characteristic frequency differences between different transition modes (short circuit, droplet, jet) are typically greater than 15 Hz. When the frequency abruptly exceeds this value and lasts for two cycles, it can be confirmed that the transition mode has changed, and further probing may result in welding defects.

[0050] When the change in average value The absolute value is less than the preset minimum detectable frequency change threshold. If the response is insufficient, the pulse amplitude for the next probe will be calculated using the following formula: in, The pulse amplitude for the next test, This sets the pulse amplitude used in this test. The minimum pulse amplitude is set. and maximum pulse amplitude When calculated When the value exceeds this range, the boundary value is automatically taken. This prevents the amplitude from increasing indefinitely due to extreme responses, thus avoiding welding quality risks. Ensure that the pulse amplitude can generate an observable fundamental perturbation, and avoid ineffective probes due to excessively small amplitudes; The maximum disturbance amplitude is limited to prevent abrupt transition modes or welding defects. In this embodiment, This corresponds to an increase in CO2 flow rate of 0.2 L / min. The corresponding CO2 flow rate is increased by 1.5 L / min. The actual value can be adjusted according to the welding wire material, shielding gas type and operating conditions.

[0051] If, during the application of a short pulse, the absolute value of the frequency difference between two consecutive adjacent droplet transition cycles exceeds a preset jump threshold, it indicates that the current pulse amplitude is too large, causing an undesirable jump in the transition mode. In this case, the system immediately terminates the current probe and reverts the pulse amplitude to the amplitude used in the previous probe. If the current probe is the first probe, it reverts to the preset minimum pulse amplitude.

[0052] The direction determination unit calculates the average droplet transition frequency over multiple consecutive droplet transition cycles to obtain a reference average value before applying the short-time pulse. The droplet transition frequency within multiple consecutive droplet transition cycles following the application of the short-time pulse is averaged to obtain the post-average value. The difference between the subsequent average and the baseline average is used as the change in average. ,Right now Calculate the product of the change in average value and the current frequency deviation. If the product is negative, the control direction gain is positive; if the product is positive, the control direction gain is negative. Here, the current frequency deviation is the reference average value. Transition frequency with target The difference, i.e. Specifically, the control direction gain is determined based on the sign of the product of the average value change and the current frequency deviation. This indicates that the applied disturbance (increasing the flow rate of the second component) causes the frequency to move closer to the target value, thus the control direction gain is positive. =+1; that is, the subsequent PID adjustment is in the same direction as the frequency deviation: when the frequency is lower than the target, the flow rate of the second component is increased, and vice versa.

[0053] This indicates that the disturbance causes the frequency to deviate further from the target, in which case the control direction gain is negative. The subsequent adjustment is inversely related to the frequency deviation; that is, the flow rate of the second component is decreased when the frequency is low, and increased when the frequency is high. Normalizing to +1 or -1 eliminates the need for subsequent PID control laws to consider direction adaptation; only multiplication by 1 is required. It can automatically correct and adjust the direction.

[0054] The gain calculation unit determines the adaptive proportional gain according to the following formula: in, For adaptive proportional gain, As the reference proportional gain, The average change For reference response amplitude; to avoid oscillation caused by excessive gain, [the following is used]: Apply upper limit limiting (e.g., not exceeding) The proportional gain in the deviation calculation and control law submodule adopts an adaptive proportional gain.

[0055] Reference proportional gain By using conventional PID tuning methods, the initial gain obtained under typical gas path response characteristics enables the closed-loop system to have sufficient regulation speed without oscillation. In this example, we take... Reference response amplitude Based on extensive process experiments, the statistical median of the average frequency change under typical disturbance amplitudes is found. The average frequency change is in the range of 4-6Hz. 5Hz is taken as the reference standard value for normalizing adaptive gain.

[0056] The results , The appropriate pulse amplitude determined in this trial is stored in the parameter area, and the trial state is exited.

[0057] The deviation calculation and control law submodule, in the non-trial state, outputs the opening adjustment amount based on the control direction gain, and controls the second electronic proportional valve according to the opening adjustment amount to optimize the protective gas mixing ratio.

[0058] The predetermined control law in the deviation calculation and control law submodule is an incremental PID control law, and the opening adjustment conforms to: in, This is the opening adjustment amount. To control the cycle number, This represents the current frequency deviation. , For control parameters, To control the directional gain. To prevent system oscillation caused by excessive single adjustment, [the following is done / implemented]. Amplitude limiting is performed (amplitude limiting is an existing technical means in PID control algorithms to prevent integral saturation and overdrive of the actuator. This process can avoid system oscillation or overshoot caused by excessive adjustment in a single adjustment). The adjusted valve opening value = the opening adjustment amount after amplitude limiting + the current valve opening value.

[0059] Current frequency deviation = ,in, For the first The average value of the periodic droplet transition frequency. For the first The periodic current corresponds to the target transition frequency, which is the output of the target frequency generation module.

[0060] Control parameters , The parameters were selected based on classic PID tuning rules and the response time of the pneumatic actuator to eliminate steady-state deviations and suppress rapid disturbances. The results were obtained through simulation and actual welding tests. It can eliminate steady-state error. It can suppress overshoot.

[0061] Specifically, the various preset parameters involved in the embodiments of this invention (including but not limited to current threshold, time window, change amplitude, reference proportional gain, reference response amplitude, time delay, pulse width, amplitude step size, preset minimum detectable frequency change threshold, and preset jump threshold) are all example values ​​obtained through process experiments and control system tuning for specific welding conditions (carbon steel solid welding wire ER70S-6, 1.0mm diameter, 2mm galvanized steel plate, 80%Ar+20%CO2 shielding gas). It should be clarified that all the above preset values ​​are merely examples given to help understand the technical solution of this invention and are not intended to limit the scope of protection of this invention. Those skilled in the art, when implementing this invention, can make conventional adjustments and optimizations to the above parameters according to the specific welding wire material, shielding gas type, welding process method, workpiece conditions, and equipment characteristics to achieve the corresponding control effect.

[0062] The controller's workflow is as follows: After the system passes the power-on self-test, it loads the default control parameters and enters standby mode.

[0063] Step 1: The welding current acquisition unit monitors the current in real time. When the current jumps from below the first threshold to above the second threshold, welding is initiated. The acoustic sensing and droplet transition frequency extraction module is activated, and the process waits for the arc to stabilize.

[0064] Step 2: Triggering a trial after arc stabilization. The benchmark statistical unit collects the real-time frequency of multiple consecutive droplet transition cycles, calculates their arithmetic mean as the benchmark average, and calculates the standard deviation. If the standard deviation is lower than the stability threshold, a trial is executed; otherwise, the statistics are repeated until the condition is met.

[0065] Step 3: Apply a disturbance. Within N consecutive droplet transition cycles, the disturbance application unit outputs a short pulse to the second electronic proportional valve at a fixed time delay after each droplet transition event. The sum of the pulse duration and the delay is less than one droplet transition cycle. After the pulse sequence ends, the average frequency of the subsequent N cycles is collected to obtain the post-average value. The change in average value is calculated as: post-average value - baseline average value.

[0066] If the absolute value of the change in the average value is less than the minimum detectable threshold, the pulse amplitude is increased by a preset step size or proportional formula, and the trial starts again from step two. If the absolute value of the frequency difference between two consecutive adjacent cycles exceeds the preset jump threshold during the pulse application process, the trial is immediately terminated, the pulse amplitude is returned to the previous safe value, and the trial is restarted.

[0067] The direction determination and gain calculation unit determines the control parameters based on the trial results. The current frequency deviation equals the reference average value minus the target transition frequency, where the target transition frequency is obtained by the target frequency generation submodule based on the current welding current. Then, the product of the average value change and the current frequency deviation is calculated. If the product is negative, the control direction gain S is set to +1; if the product is positive, S is set to -1. Simultaneously, adaptive proportional gain... according to Calculation. After a successful trial, the state locking unit saves S, Based on the current pulse amplitude, the system exits the trial state and enters steady-state closed-loop regulation.

[0068] Step 4: In steady-state closed-loop regulation, the real-time droplet transfer frequency and average welding current are acquired in each control cycle, based on... Query the corresponding target transition frequency Calculate real-time frequency deviation The deviation calculation and control law submodule uses an incremental PID control law to calculate the opening adjustment of the second electronic proportional valve according to the formula, where... and These represent the frequency deviations of the previous cycle and the two cycles prior, respectively. After limiting the output opening adjustment, the second electronic proportional valve is adjusted to change the protective gas mixing ratio, affecting the subsequent droplet transition frequency and forming a closed-loop control.

[0069] Step 5: During continuous welding, the process change adaptive unit continuously monitors the welding current. If the change in welding current exceeds a preset percentage within a preset time window, it is determined that the operating conditions have changed significantly. The system then re-triggers steps 2 to 4, updating the control direction gain, adaptive proportional gain, and appropriate pulse amplitude to adapt to the new welding conditions.

[0070] The above are merely embodiments of the present invention. The circuits, electronic components, and modules involved are all prior art, fully achievable by those skilled in the art, and require no further explanation. The content protected by this application does not involve improvements to the software and methods. Commonly known structures and characteristics in the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are able to access all prior art in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A shielding gas flow blending controller for a welding apparatus, characterized by: Includes a gas fusion unit, comprising a first electronic proportional valve and a second electronic proportional valve; An audio sensing unit is installed on the welding torch and outputs digital audio signals; The droplet transition frequency extraction module is connected to the audio sensing unit and outputs the real-time droplet transition frequency and corresponding timestamp for each droplet transition cycle. Welding current acquisition unit, outputs welding current; The target frequency generation submodule is connected to the welding current acquisition unit and outputs the target transition frequency corresponding to the welding current. The mixing ratio optimization controller is connected to the droplet transition frequency extraction module and the target frequency generation submodule. The mixing ratio optimization controller includes an encoded perturbation trial submodule and a deviation calculation and control law submodule. The encoded perturbation probe submodule includes: After receiving the trigger signal, the disturbance application unit outputs a short pulse to the second electronic proportional valve at a fixed time delay after each droplet transition event during multiple consecutive droplet transition cycles. The period during which the disturbance application unit outputs the short pulse is a trial state. The direction determination unit calculates a baseline average value by averaging the droplet transition frequencies over multiple consecutive droplet transition cycles before the short-time pulse is applied; it then calculates a post-average value by averaging the droplet transition frequencies over multiple consecutive droplet transition cycles after the short-time pulse is applied, and uses the difference between the post-average value and the baseline average value as the average value change; the control direction gain is determined based on the product of the average value change and the current frequency deviation, where the current frequency deviation is the difference between the baseline average value and the target transition frequency. The deviation calculation and control law submodule outputs an opening adjustment amount based on the control direction gain in the non-trial state, and controls the second electronic proportional valve according to the opening adjustment amount.

2. The protective gas flow mixing controller for welding equipment as described in claim 1, characterized in that: The duration of the short pulse is less than the duration of one droplet transition cycle, and the sum of the fixed time delay and the duration of the short pulse is less than the duration of one droplet transition cycle.

3. A protective gas flow mixing controller for welding equipment as described in claim 1, characterized in that: The coded perturbation probe submodule also includes a benchmark statistics unit, which, after receiving the trigger signal, collects the real-time droplet transition frequency of multiple droplet transition cycles and calculates the standard deviation. When the standard deviation is lower than the stability threshold, the perturbation application unit outputs the short-time pulse.

4. A protective gas flow mixing controller for welding equipment as described in claim 1, characterized in that: The control direction gain is determined as follows: if the product of the average change and the current frequency deviation is negative, the control direction gain is positive; if the product is positive, the control direction gain is negative.

5. A protective gas flow mixing controller for welding equipment as described in claim 1, characterized in that: The encoded perturbation probing submodule also includes an adaptive amplitude adjustment unit. When the absolute value of the change in the average value is less than the preset minimum detectable frequency change threshold, the amplitude of the short-time pulse is increased in subsequent probing. If the absolute value of the frequency difference between two consecutive adjacent droplet transition cycles exceeds the preset jump threshold during the application of the short-time pulse, the current probing is terminated and the amplitude of the short-time pulse is reduced to the amplitude used in the previous probing.

6. A protective gas flow mixing controller for welding equipment as described in claim 1, characterized in that: The encoded perturbation probing submodule also includes a gain calculation unit, which determines the adaptive proportional gain according to the following formula: in, For adaptive proportional gain, As the reference proportional gain, The average change The reference response amplitude is used; the proportional gain in the deviation calculation and control law submodule adopts an adaptive proportional gain.

7. A protective gas flow mixing controller for welding equipment as described in claim 6, characterized in that: The predetermined control law in the deviation calculation and control law submodule is an incremental PID control law, and the opening adjustment amount conforms to: in, This is the opening adjustment amount. To control the cycle number, This represents the current frequency deviation. , For control parameters, To control directional gain.

8. A protective gas flow mixing controller for welding equipment as described in claim 1, characterized in that: The droplet transition frequency extraction module includes an envelope detection unit and a smoothing filter unit; the smoothing filter unit performs an exponentially weighted moving average on the real-time droplet transition frequency; the envelope detection unit uses Hilbert transform to extract the instantaneous envelope.

9. A protective gas flow mixing controller for welding equipment as described in claim 1, characterized in that: The audio sensing unit includes a microphone, a preamplifier, an anti-aliasing filter, and an analog-to-digital converter. The welding current acquisition unit includes a current sensor and an analog-to-digital converter.

10. A protective gas flow mixing controller for welding equipment as described in claim 1, characterized in that: The encoded perturbation probing submodule further includes a probing trigger judgment unit, which generates and outputs a trigger signal when any of the following conditions are met: When the system is powered on or when the arc is restarted after welding has stopped, the welding current is detected to jump from below the first threshold to above the second threshold. The variation in welding current within the time window exceeds the percentage threshold. Received an external manual trigger signal.

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