Method for trace detection of residual magnesium in spheroidization rate of molten iron of injection molding machine template casting
By monitoring the ratio of plasma signal intensity and energy level distribution parameters, the identification problem of magnesium element detection under high-temperature conditions was solved, and stable detection of the spheroidization rate of molten iron in injection molding machine template castings was achieved, improving the detection accuracy and reproducibility of magnesium element.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUNAN XINQUAN TECH CO LTD
- Filing Date
- 2026-04-13
- Publication Date
- 2026-05-12
AI Technical Summary
During the smelting process of ductile iron for heavy injection molding machine molds, the magnesium content inside the molten iron affects the spheroidization grade and mechanical properties of the casting. Existing technologies are unable to effectively suppress the non-stationary fluctuations of plasma background radiation under high-temperature conditions, resulting in a decrease in the identification of trace magnesium elements.
By monitoring the transient ratio of the first-band signal intensity to the second-band signal intensity during plasma evolution, the transient energy level distribution parameters of the plasma are determined. When the signal-to-noise ratio characteristic threshold is reached, spectral data acquisition is triggered. Combining the energy transition coupling characteristics of rare earth element ion lines and magnesium atom lines, an evaluation logic characterizing the stability of the spherical structure is constructed to identify the occurrence state and distribution characteristics of magnesium in high-temperature melts.
It effectively reduces the masking of trace magnesium signals by random fluctuations in background noise, improves the stability and reproducibility of magnesium detection, and ensures detection accuracy in complex production environments.
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Figure CN122016768A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of spectroscopic analysis technology and relates to a method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings. Background Technology
[0002] Currently, in the smelting process of ductile iron for heavy injection molding machine molds, the magnesium content inside the molten iron directly affects the spheroidization grade and mechanical properties of the casting. Laser-induced breakdown spectroscopy, as a rapid on-site component analysis method, utilizes high-energy laser pulses to ablate the surface of molten iron to generate plasma. By collecting and analyzing the spectral signals emitted by the plasma, real-time monitoring of the metal component content can be achieved. Under high-temperature conditions of 1450℃ to 1550℃, the plasma excitation process is accompanied by extremely strong continuous background radiation. Furthermore, the thermal convection on the surface of the molten iron and the dynamic evolution of the oxide film cause this background radiation to exhibit non-stationary step fluctuations. This randomly changing background signal masks the characteristic spectral lines of trace magnesium elements with a concentration below 0.04%, resulting in a decrease in the identification of target characteristic peaks in the spectral data acquired by the detection system.
[0003] To suppress background interference, conventional methods involve increasing the excitation energy or setting a fixed sampling delay to capture the signal. However, since atomic fluorescence lifetime and continuous background radiation overlap on the time evolution axis, and transient changes in liquid surface emissivity alter the plasma quenching rate, simply increasing the excitation energy level cannot resolve the technical contradiction of the mismatch between the trigger window and the physical evolution stage of the plasma, leading to random deviations in the measurement data. The industry has attempted to introduce multi-state recognition and compensation logic. For example, Chinese invention patent CN114136458B discloses an online detection method and system for multi-state temperature of molten metal fluid. It uses deep neural networks to identify the on-site dust interference state and construct different detection models, which has reference value in terms of environmental optical path compensation. This type of multi-state classification based on image processing focuses on the macroscopic classification of external dust concentration and does not address the transient physical characteristics of plasma evolution. The challenge of trace element detection lies in the deep coupling between atomic radiation signals and blackbody background noise in the spectral domain at the nanosecond scale. Without real-time capture of the physical inflection point of the internal energy level distribution of the plasma, relying solely on external environmental state recognition cannot solve the problem of background radiation step fluctuations masking trace spectral lines.
[0004] Therefore, how to utilize the physical state characteristics during plasma evolution to determine the spectral acquisition time in real time, suppress interference from non-stationary background radiation, and improve the measurement stability of residual magnesium traces has become the technical problem to be solved by this invention. Summary of the Invention
[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings, comprising the following steps: Step 101: Use the excitation pulse radiation unit to ablate the surface of the molten iron in the injection molding machine template casting to generate plasma; Step 102: Simultaneously acquire the first band signal intensity and the second band signal intensity during the plasma evolution process; wherein, the first band corresponds to the atomic spontaneous emission spectrum of magnesium in the molten iron, and the second band corresponds to the continuous background radiation spectrum of the plasma. Step 103: Determine the transient energy level distribution parameters of the plasma based on the transient ratio of the signal intensity of the first band to the signal intensity of the second band, and monitor the time-domain evolution trajectory of the transient energy level distribution parameters as the plasma cools down. Step 104: Compare the time-domain evolution trajectory of the transient energy level distribution parameters with the signal-to-noise ratio characteristic threshold determined based on the background signal attenuation characteristic points, and trigger the opening of the acquisition gate window to extract trace spectral data of magnesium in molten iron when the transient energy level distribution parameters reach the signal-to-noise ratio characteristic threshold. Step 105: Calculate the mass fraction of magnesium in the molten iron based on trace spectral data and a preset elemental mapping model. Step 106: Determine and output the evaluation parameters characterizing the spheroidization quality of the injection molding machine template casting based on the mass fraction of magnesium.
[0006] Preferably, the method includes step 201, synchronously acquiring the reference spectral intensity of the matrix iron element in the plasma; step 202: when executing step 104, identifying the physical transition point of the plasma from thermodynamic equilibrium state to atomic spontaneous emission-dominated state based on the first derivative of the reference spectral intensity, and locking the opening time of the acquisition gate window at the physical transition point.
[0007] Preferably, the center wavelength of the first band is 285.21 nm and the center wavelength of the second band is 286.00 nm; in step 103, the transient energy level distribution parameter is defined as the real-time intensity ratio of the peak intensity at 285.21 nm to the background signal intensity at 286.00 nm.
[0008] Preferably, step 401 involves supplying an inert protective gas with a flow rate of 5 L / min to 15 L / min to the active area of the excitation pulse radiation unit to form a local reducing gas phase interface on the surface of the molten iron. The local reducing gas phase interface is used to suppress the secondary oxidation loss of magnesium atoms.
[0009] Preferably, the method includes step 501, extracting iron element spectral line pairs in the plasma with an excitation energy level difference greater than 2 eV; step 502, establishing a thermodynamic temperature feedback closed loop based on the intensity ratio of the iron element spectral line pairs, and correcting the integral width of the acquisition gate window in step 104 when the temperature of the molten iron surface fluctuates within the range of 1400℃ to 1550℃.
[0010] Preferably, step 105 specifically includes: establishing an energy balance mapping rule between rare earth element ion lines and the signal intensity of the first band; and using the synergistic correlation characteristics between heterogeneous elements to identify the occurrence state of magnesium in high-temperature melt.
[0011] Preferably, the method includes step 701, synchronously monitoring the intensity of the characteristic spectral lines of the inert protective gas delivered in step 401; and step 702, calculating the change coefficient of optical path transmittance based on the attenuation of the intensity of the characteristic spectral lines of the inert protective gas, and performing amplitude gain compensation on the trace spectral data obtained in step 104 based on the change coefficient.
[0012] Preferably, in step 104, the opening delay D of the gated window is collected. gate The following logic must be satisfied: , where D gate To collect the opening delay of the gated window, t opt The sampling time when the transient energy level distribution parameters first reach the signal-to-noise ratio characteristic threshold is δt, and δt is the preset system electrical signal transmission delay compensation amount.
[0013] Preferably, the elemental mapping model in step 105 is established by: collecting the spectral evolution curves of standard samples with known magnesium content in the range of 1450℃ to 1500℃; extracting the real-time ratio characteristics of the signal intensity of the first band and the signal intensity of the second band to construct a quantitative mapping matrix that excludes blackbody radiation interference.
[0014] Preferably, the method includes step 1001, where when the measured evaluation parameter corresponds to a spheroidization rate of less than 90%, a quality feedback signal characterizing the deviation of the molten iron composition is output; and step 1002, where, based on the mass fraction of magnesium, the magnesium content compensation data corresponding to the addition of spheroidizing agent to the molten iron of the injection molding machine template casting is calculated.
[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In the detection of residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings, by monitoring the change gradient of the intensity of the reference spectral line of the matrix iron, a deterministic correlation between the spectral acquisition action and the evolution state of the plasma energy level is established, so that the spectral acquisition window is automatically locked to the physical transition point from the decay of continuous background radiation to the atomic fluorescence dominant state, thereby reducing the masking effect of random fluctuations in background noise caused by the flashing of the oxide film on the surface of the molten iron or violent thermal convection on the trace magnesium signal.
[0016] 2. By combining the energy transition coupling characteristics of rare earth element ion lines and magnesium atom lines, an evaluation logic for characterizing the stability of spheroidized structure is constructed. This synergistic correlation mechanism between heterogeneous elements can identify the occurrence state and distribution characteristics of magnesium in high-temperature melt, thereby enabling physical prediction of the spheroidization degradation risk of thick cross-section castings based on conventional component detection.
[0017] 3. A thermodynamic state feedback loop is established using spectral lines with significant differences in excitation energy levels in the iron matrix. The system corrects the spectral acquisition sequence in real time based on the transient ratio of spectral line intensities, automatically offsetting the changes in spectral physical morphology and Stark broadening caused by fluctuations in molten iron temperature within the range of 1400℃ to 1550℃, ensuring the stability of the detection logic under extreme trace conditions. Simultaneously, characteristic spectral lines of the protective gas in the detection field and residual entropy values of the metal oxide molecular bands are extracted to construct a dual verification mechanism for the detection environment and the excitation interface. The protective gas spectrum is used as a scale for optical path transmittance, supplemented by the molecular band waveform complexity to determine the phase purity of the excitation region, achieving logical stripping of interference from smoke scattering and false signals from surface oxide slag, thus improving the detection reproducibility in complex production environments. Attached Figure Description
[0018] Figure 1 This is a flowchart illustrating the process of the method for detecting the spheroidization rate and residual magnesium traces in molten iron of injection molding machine template castings according to the present invention. Figure 2 This is a schematic diagram illustrating the module interaction and operational logic of the trace detection system of the present invention.
[0019] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0020] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.
[0021] A method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings includes the following steps: Step 101: Use the excitation pulse radiation unit to ablate the surface of the molten iron in the injection molding machine template casting to generate plasma; Step 102: Simultaneously acquire the first band signal intensity and the second band signal intensity during the plasma evolution process; wherein, the first band corresponds to the atomic spontaneous emission spectrum of magnesium in the molten iron, and the second band corresponds to the continuous background radiation spectrum of the plasma. Step 103: Determine the transient energy level distribution parameters of the plasma based on the transient ratio of the signal intensity of the first band to the signal intensity of the second band, and monitor the time-domain evolution trajectory of the transient energy level distribution parameters as the plasma cools down. Step 104: Compare the time-domain evolution trajectory of the transient energy level distribution parameters with the signal-to-noise ratio characteristic threshold determined based on the background signal attenuation characteristic points, and trigger the opening of the acquisition gate window to extract trace spectral data of magnesium in molten iron when the transient energy level distribution parameters reach the signal-to-noise ratio characteristic threshold. Step 105: Calculate the mass fraction of magnesium in the molten iron based on trace spectral data and a preset elemental mapping model. Step 106: Determine and output the evaluation parameters characterizing the spheroidization quality of the injection molding machine template casting based on the mass fraction of magnesium.
[0022] Preferably, the method includes step 201, synchronously acquiring the reference spectral intensity of the matrix iron element in the plasma; step 202, when executing step 104, identifying the physical inflection point of the plasma transitioning from thermodynamic equilibrium to atomic spontaneous emission-dominated state based on the first derivative of the reference spectral intensity, and locking the opening time of the acquisition gate window at the physical inflection point.
[0023] Preferably, the center wavelength of the first band is 285.21 nm and the center wavelength of the second band is 286.00 nm; in step 103, the transient energy level distribution parameter is defined as the real-time intensity ratio of the peak intensity at 285.21 nm to the background signal intensity at 286.00 nm.
[0024] Preferably, step 401 involves supplying an inert protective gas with a flow rate of 5 L / min to 15 L / min to the active area of the excitation pulse radiation unit to form a local reducing gas phase interface on the surface of the molten iron. The local reducing gas phase interface is used to suppress the secondary oxidation loss of magnesium atoms.
[0025] Preferably, the method includes step 501, extracting iron element spectral line pairs in the plasma with an excitation energy level difference greater than 2 eV; step 502, establishing a thermodynamic temperature feedback closed loop based on the intensity ratio of the iron element spectral line pairs, and correcting the integral width of the acquisition gate window in step 104 when the temperature of the molten iron surface fluctuates within the range of 1400℃ to 1550℃.
[0026] Preferably, step 105 specifically includes: establishing an energy balance mapping rule between rare earth element ion lines and the signal intensity of the first band; and using the synergistic correlation characteristics between heterogeneous elements to identify the occurrence state of magnesium in high-temperature melt.
[0027] Preferably, the method includes step 701, synchronously monitoring the intensity of the characteristic spectral lines of the inert protective gas delivered in step 401; and step 702, calculating the change coefficient of optical path transmittance based on the attenuation of the intensity of the characteristic spectral lines of the inert protective gas, and performing amplitude gain compensation on the trace spectral data obtained in step 104 based on the change coefficient.
[0028] Preferably, in step 104, the opening delay D of the gated window is collected. gate The following logic must be satisfied: , where D gate To collect the opening delay of the gated window, t opt The sampling time when the transient energy level distribution parameters first reach the signal-to-noise ratio characteristic threshold is δt, and δt is the preset system electrical signal transmission delay compensation amount.
[0029] Preferably, the elemental mapping model in step 105 is established by: collecting the spectral evolution curves of standard samples with known magnesium content in the range of 1450℃ to 1500℃; extracting the real-time ratio characteristics of the signal intensity of the first band and the signal intensity of the second band to construct a quantitative mapping matrix that excludes blackbody radiation interference.
[0030] Preferably, the method includes step 1001, where when the measured evaluation parameter corresponds to a spheroidization rate of less than 90%, a quality feedback signal characterizing the deviation of the molten iron composition is output; and step 1002, where, based on the mass fraction of magnesium, the magnesium content compensation data corresponding to the addition of spheroidizing agent to the molten iron of the injection molding machine template casting is calculated.
[0031] Example 1: In the production site of heavy injection molding machine templates with a casting weight of tens of tons, the surface of ductile iron molten iron, maintained at a temperature between 1450℃ and 1550℃, exhibits thermal convection and dynamic oxide film formation. This results in continuous background radiation accompanying the plasma generated by the excitation pulse radiation unit melting the molten iron surface, with the background radiation exhibiting step-like fluctuations. These fluctuations mask the atomic spontaneous emission spectrum of trace magnesium elements with a mass fraction of less than 0.04%, reducing the identification of target feature peaks extracted by the fixed-delay spectral acquisition logic. The excitation pulse radiation unit delivers an inert protective gas with a flow rate of 10L / min to the action area to form a local reducing gas phase interface and melt the molten iron surface to generate plasma. The spectral detection system simultaneously acquires the first and second band signal intensities during the plasma evolution process. The first band, with a center wavelength of 285.21nm, corresponds to the atomic spontaneous emission spectrum of magnesium elements in the molten iron, and the second band, with a center wavelength of 286.00nm, corresponds to the continuous background radiation spectrum of the plasma.
[0032] The transient energy level distribution parameters of the plasma are determined based on the transient ratio of the signal intensity of the first band to that of the second band, and the temporal evolution trajectory of the transient energy level distribution parameters during the plasma cooling process is monitored. The system compares the temporal evolution trajectory of the transient energy level distribution parameters with the signal-to-noise ratio (SNR) characteristic threshold determined based on the background signal attenuation feature points. When the transient energy level distribution parameters reach the SNR characteristic threshold, the physical inflection point of the plasma transitioning from thermodynamic equilibrium to atomic spontaneous emission-dominated state is identified based on the first derivative of the reference spectral intensity of the matrix iron element in the plasma acquired simultaneously. The opening time of the acquisition gate is locked at this physical inflection point to extract trace spectral data of magnesium element in the molten iron. The opening delay D of the acquisition gate is... gate The calculation formula is , where D gate To collect the opening delay of the gated window, t opt The sampling time when the transient energy level distribution parameters reach the signal-to-noise ratio characteristic threshold is defined as δt, which is a preset system electrical signal transmission delay compensation amount. The system calculates the mass fraction of magnesium in the molten iron based on trace spectral data and a preset elemental mapping model. The evaluation parameters characterizing the spheroidization quality of the injection molding machine template casting are determined and output based on the mass fraction of magnesium in the molten iron. The opening mechanism of the acquisition gate window sets the time boundary based on the quantitative correlation between the time-domain evolution trajectory of the transient energy level distribution parameters and the background signal attenuation characteristic points, avoiding the timing deviation caused by the background fluctuation of thermal radiation on the surface of the high-temperature melt, and ensuring that the physical action of extracting trace spectral data is within the atomic spontaneous emission dominant state range.
[0033] Example 2: In a medium-frequency induction melting test platform, the test device contained 50 kg of ductile iron molten iron and maintained the overall temperature between 1450℃ and 1550℃. A high-frequency arc generator was placed 500 mm above the surface of the molten iron, continuously injecting Gaussian white noise with a signal-to-noise ratio of 20 dB into the acquisition area. Simultaneously, a directional fan was activated at a wind speed of 3.2 m / s to disturb the oxide film on the surface of the molten iron, causing non-periodic thermal radiation step fluctuations with a frequency of 0.1 Hz to 5.3 Hz to occur on the surface of the molten iron. The test platform was equipped with a grating spectrometer with a resolution of 0.01 nm, simultaneously acquiring wavelengths covering 28... A physical verification environment containing continuous blackbody radiation noise and electromagnetic interference was constructed using a spectral sequence from 0 nm to 290 nm. The system acquired the temporal evolution rate and data throughput load of the plasma cooling process, and determined the sampling period of the spectral detection system based on these two physical indicators. When the sampling period was greater than 1.5 μs, the time interval between adjacent sampling points spanned the physical transition point from the thermodynamic equilibrium state to the atomic spontaneous emission-dominated state of the plasma. When the sampling period was less than 0.5 μs, the spectral detection system accumulated redundant continuous background spectral data. The experimental system applied this association rule to set the sampling period to 1.1 μs and executed the steps. 104. To identify physical inflection points, a 5- to 11-point Savitzky-Golay smoothing filter was applied to the synchronously acquired plasma matrix iron reference spectral intensity sequence to remove high-frequency random noise in the early evolution stage. The first-order time derivative of the filtered intensity data was calculated. The sampling moment when the first-order derivative crossed from a negative value to zero and the absolute value of the change rate remained stable was identified as a physical inflection point. This represents the transient boundary of the plasma transition from a thermodynamic equilibrium state dominated by continuous background radiation to a state dominated by atomic spontaneous emission. The system extracts the intensity ratio of iron spectral lines with an excitation energy level difference greater than 2 eV when the surface temperature of the molten iron fluctuates between 1400℃ and 1550℃. The preset temperature-integral width correction table was consulted. For every 50°C increase in temperature, the integration width of the acquisition gate window was increased by 100ns to 200ns to compensate for the increased atomic fluorescence lifetime caused by the temperature increase. The experiment set up a control sample group that used a fixed 1.5μs delay time to trigger the acquisition action, and the sample group of the present invention that used dynamic triggering based on transient energy level distribution parameters. For the opening delay of the acquisition gate window, the experiment set up three independent boundary test groups with system electrical signal transmission delay compensation amounts of 0 nanoseconds, 50 nanoseconds, and 100 nanoseconds, respectively, and recorded the nonlinear effect data of the delay compensation amount on the extraction intensity of the characteristic peak of trace magnesium.
[0034] An inert protective gas with a flow rate of 10.5 L / min is delivered to the action area by an excitation pulse radiation unit, ablating the surface of the molten iron to generate plasma. A spectral detection system extracts the signal intensity of the first band with a center wavelength of 285.21 nm and the signal intensity of the second band with a center wavelength of 286.00 nm, and calculates the transient ratio to obtain the transient energy level distribution parameters of the plasma. Data from the sample group of this invention shows that these transient energy level distribution parameters remain in the range of 0.11 to 0.18 within 0.6 μs after plasma generation, and reach a signal-to-noise ratio characteristic threshold of 2.5 between 0.9 μs and 1.1 μs. The system extracts the reference spectral line intensity of the matrix iron element in the plasma at 287.40 nm and calculates its first derivative, identifying the zero-crossing point of this derivative, i.e., the physical inflection point, and then follows the formula... With the acquisition gating window open, the trace spectral data extracted by the sample group of this invention achieved a net signal intensity of 4612 counts after background subtraction. In contrast, the comparison sample group, experiencing a thermal radiation step fluctuation, fell into the background radiation surge region with a fixed delay of 1.5 μs, resulting in an extracted net signal intensity of 785 counts, which disappeared within a background baseline of 1250 counts. The spectral characteristics output by the sample group of this invention eliminate the physical interference of thermal radiation step fluctuations. The three independent boundary test groups output differentiated measurement accuracy indicators in 50 consecutive excitation tests. When the system electrical signal transmission delay compensation was set to 0 nanoseconds, the acquisition gating window opened earlier than the atomic spontaneous emission dominant state region, and the relative standard deviation of the magnesium element mass fraction relative to the standard chemical titration value was 15.6%. When the delay compensation was set to 50 nanoseconds... When the relative standard deviation converged to 1.1%, and the time delay compensation was set to 100 nanoseconds, the plasma fluorescence quenching caused the intensity of the characteristic peak of magnesium to decay, and the relative standard deviation increased to 23.4%. The extreme value convergence data output by the system defined the optimal working window for the compensation amount of 50 nanoseconds to match the current hardware transmission characteristics. The above-mentioned spectral acquisition data of the noisy molten iron presents the actual operating state of the system under thermal convection and oxide film disturbance. The system determines the transient energy level distribution parameters based on the transient ratio of the first band signal intensity to the second band signal intensity, and locks the opening time of the acquisition gate window in conjunction with the first derivative of the reference spectral intensity of the matrix iron element, extracts trace spectral data of magnesium element in molten iron, and outputs evaluation parameters characterizing the spheroidization quality of the injection molding machine template casting based on the mass fraction of magnesium element.
[0035] Example 3: Before the heavy-duty injection molding machine template casting molten iron residual magnesium trace detection system is put into continuous operation, the system performs environmental initialization and parameter calibration procedures, emits a reference laser signal with a pulse width of 100ps to the detection area, simultaneously starts the internal high-speed timer and monitors the photoelectric conversion output port of the spectral detection system, obtains the time difference between the emission time of the reference laser signal and the rise time of the response signal generated by the photoelectric conversion output port, and determines it as the system electrical signal transmission delay compensation amount δt. During the system initialization stage, a pure iron sample block is selected and maintained at 1450℃, and the pulse radiation unit is excited to ablate the sample block surface to collect a continuous background radiation intensity sequence of 286.00nm, and calculates the average value of 50 sets of continuous pulse intensity. With strength standard deviation Set the signal-to-noise ratio feature threshold as The coefficient k takes values from 3 to 5. The laser trigger level signal and the response signal of the spectral detection system are synchronously monitored using the 510.55nm spectral line reference of the standard copper sample. The pulse measurement time interval is set as the system electrical signal transmission delay compensation amount δt. Plasma is generated on the surface of the molten iron. The time series data sequence of the second band signal intensity in the early stage of plasma cooling is obtained, and the time second derivative of the second band signal intensity is calculated. The sampling time when the time second derivative reaches zero is extracted as the background signal attenuation feature point. The transient ratio of the first band signal intensity to the second band signal intensity at this sampling time is obtained. The system calculates the product of the transient ratio and the preset baseline fluctuation coefficient, and sets the product result as the signal-to-noise ratio feature threshold.
[0036] When the transient energy level distribution parameters reach the signal-to-noise ratio characteristic threshold, the physical inflection point is identified based on the zero-crossing point of the first derivative of the reference spectral intensity of the iron element in the matrix, triggering the opening of the acquisition gating window. The spectral detection system inputs the first-band signal intensity and the second-band signal intensity acquired within the acquisition gating window into a preset elemental mapping model. The elemental mapping model performs a difference operation, subtracting the second-band signal intensity from the first-band signal intensity to obtain the net radiation characteristic value of magnesium. A linear regression matrix pre-constructed based on multiple sets of standard ductile iron samples with known magnesium mass fractions is retrieved to establish the mapping slope between the standard magnesium mass fraction and the corresponding net radiation characteristic value. The system then converts the extracted net radiation characteristic value into the magnesium mass fraction in the molten iron based on the linear regression matrix. The system outputs evaluation parameters characterizing the spheroidization quality of the injection molding machine template casting. It establishes an energy balance mapping rule between the cerium ion line CeII 280.12nm and the magnesium atomic line MagnesiumI 285.21nm. It uses the cerium spheroidization core to identify the high-temperature melt occurrence state by synergistic excitation of magnesium atoms, thereby solving the concentration analysis deviation caused by the matrix effect. Based on the magnesium mass fraction input into the preset large cross-section casting critical absorption kinetic model, it calculates the deviation of the mass fraction from the nominal spheroidization lower limit threshold of 0.035%. It outputs a structural density expectation index of 0 to 1 to characterize the spheroidization quality of the injection molding machine template casting. This logic relies on time difference measurement and second derivative algorithm to define the trigger boundary. It uses a dual-band difference algorithm to eliminate the interference of continuous blackbody radiation and obtain quantitative analysis data.
[0037] Example 4: When deploying a residual magnesium trace detection system on an injection molding machine template casting production line, in order to eliminate the blackbody radiation baseline shift and spectral transmission attenuation caused by heterogeneous smelting equipment, the system initiates a pre-deployment calibration procedure on-site. The calibration device extracts 5 sets of standard samples with known magnesium mass fractions covering the target sphericity range and heats them to maintain a constant temperature of 1500℃. The pulsed radiation unit is excited to ablate the surface of the standard sample to generate plasma. The spectral detection system collects the continuous time series of the second band signal intensity. The system calculates the ratio of the standard deviation to the mean of the continuous time series to extract the thermal radiation fluctuation characteristic parameter, and multiplies it with the preset dark current variance of the photodetector to calculate the initialized baseline fluctuation coefficient.
[0038] The system sequentially detects the spectra of five sets of standard samples. Based on the first derivative of the reference spectral intensity of the iron element in the plasma matrix, it extracts the first-band and second-band signal intensities of each standard sample at the physical inflection point. The elemental mapping model calculates the net radiation characteristic value of each standard sample by subtracting the second-band signal intensity from the first-band signal intensity and sets it as the independent variable. At the same time, it sets the corresponding known magnesium element mass fraction as the dependent variable. The system runs a partial least squares algorithm based on the independent and dependent variables to solve for the correlation slope parameters, thereby generating a linear regression matrix adapted to the current production line. The system writes the baseline fluctuation coefficient and the linear regression matrix into the storage module of the main control chip. This pre-deployment calibration procedure constructs the internal mapping logic of the elemental mapping model based on the spectral response data of the standard materials, and sets the parameter analysis basis of the system under the current operating conditions.
[0039] Example 5: Addressing the physical boundary state of nonlinear attenuation of optical path transmission efficiency in the spectral detection system caused by the adhesion of smelting fumes and splashes during continuous detection of molten iron in injection molding machine templates, this system employs a dynamic optical path compensation and online fault-tolerant procedure to construct an adaptive operating benchmark under contaminated conditions. The spectral detection system acquires the current count value of the reference spectral line intensity of the matrix iron element with a center wavelength of 287.40 nm within a continuous measurement cycle. The main control chip reads the reference spectral line benchmark value pre-stored in the non-volatile storage module under the initial contamination-free state. The system calculates the difference between the reference spectral line benchmark value and the current count value, divides it by the reference spectral line benchmark value to convert it into a quantization attenuation ratio, and inputs the quantization attenuation ratio into a preset quantization threshold range module to determine the trigger level for hardware maintenance. When the quantization attenuation ratio is within the compensation range of 10% to 30%, the system generates a dynamic gain coefficient K based on the reference spectral line benchmark value and the current count value. gain Dynamic gain coefficient K gain The calculation formula is , where K gain I is the dimensionless dynamic gain coefficient. refo As a reference spectral standard, I ref Given the current count value, the system calculates the dynamic gain coefficient K. gain The product of the net radiation eigenvalues output by the elemental mapping model yields the compensation characteristic parameter. Based on the compensation characteristic parameter and the linear regression matrix, the mass fraction of magnesium in the molten iron is calculated. When the quantization attenuation ratio is greater than the physical limit threshold of 30%, the system locks the trigger logic of the acquisition gate window and outputs a high-level command pulse to the external pneumatic actuator to drive the high-pressure inert gas to purge the optical window. This fault-tolerant procedure transforms the intensity drift data of the reference spectral line into a signal compensation operator and a physical intervention trigger basis, maintaining the consistency of data analysis of the trace analysis model in a continuous heavily polluted environment.
[0040] When the system faces the final working condition of outputting the casting control basis at the front end, the main control chip starts the spheroidization quality mapping procedure based on the measured mass fraction of magnesium in the molten iron. It extracts the critical absorption kinetic model for large-section castings that is preset in the non-volatile storage module. This model defines the nominal lower spheroidization threshold and the nominal upper spheroidization threshold. The system calculates the difference between the mass fraction of magnesium in the molten iron and the nominal lower spheroidization threshold, and divides it by the numerical difference between the nominal upper spheroidization threshold and the nominal lower spheroidization threshold to obtain the structural density expectation index. The system sets the structural density expectation index as the evaluation parameter characterizing the spheroidization quality of the injection molding machine template casting and sends it to the production line interception logic unit via the industrial bus. This procedure transforms the quantitative analysis data of the spectral detection system into the equipment action trigger basis of the metallurgical production line.
[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.
[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings, characterized in that, Includes the following steps: Step 101: Use the excitation pulse radiation unit to ablate the surface of the molten iron in the injection molding machine template casting to generate plasma; Step 102: Simultaneously acquire the first band signal intensity and the second band signal intensity during the plasma evolution process; wherein, the first band corresponds to the atomic spontaneous emission spectrum of magnesium in the molten iron, and the second band corresponds to the continuous background radiation spectrum of the plasma. Step 103: Determine the transient energy level distribution parameters of the plasma based on the transient ratio of the signal intensity of the first band to the signal intensity of the second band, and monitor the time-domain evolution trajectory of the transient energy level distribution parameters as the plasma cools down. Step 104: Compare the time-domain evolution trajectory of the transient energy level distribution parameters with the signal-to-noise ratio characteristic threshold determined based on the background signal attenuation characteristic points, and trigger the opening of the acquisition gate window to extract trace spectral data of magnesium in molten iron when the transient energy level distribution parameters reach the signal-to-noise ratio characteristic threshold. Step 105: Calculate the mass fraction of magnesium in the molten iron based on trace spectral data and a preset elemental mapping model. Step 106: Determine and output the evaluation parameters characterizing the spheroidization quality of the injection molding machine template casting based on the mass fraction of magnesium.
2. The method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings according to claim 1, characterized in that, The process includes step 201, which involves synchronously acquiring the reference spectral intensity of the matrix iron element in the plasma; and step 202, which, while executing step 104, identifies the physical inflection point of the plasma transitioning from a thermodynamic equilibrium state to an atomic spontaneous emission-dominated state based on the first derivative of the reference spectral intensity, and locks the opening time of the acquisition gate window at the physical inflection point.
3. The method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings according to claim 1, characterized in that, The center wavelength of the first band is 285.21 nm, and the center wavelength of the second band is 286.00 nm. In step 103, the transient energy level distribution parameter is defined as the real-time intensity ratio of the peak intensity at 285.21 nm to the background signal intensity at 286.00 nm.
4. The method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings according to claim 1, characterized in that, The process includes step 401, in which an inert protective gas with a flow rate of 5 L / min to 15 L / min is supplied to the active area of the excitation pulse radiation unit to form a local reducing gas phase interface on the surface of the molten iron. The local reducing gas phase interface is used to suppress the secondary oxidation loss of magnesium atoms.
5. The method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings according to claim 2, characterized in that, The process includes step 501, extracting iron element spectral line pairs in the plasma with an excitation energy level difference greater than 2 eV; step 502, establishing a thermodynamic temperature feedback closed loop based on the intensity ratio of the iron element spectral line pairs, and correcting the integral width of the acquisition gate window in step 104 when the temperature of the molten iron surface fluctuates within the range of 1400℃ to 1550℃.
6. The method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings according to claim 1, characterized in that, Step 105 specifically includes: establishing an energy balance mapping rule between rare earth element ion lines and the signal intensity of the first band; and using the cooperative correlation characteristics between heterogeneous elements to identify the occurrence state of magnesium in high-temperature melt.
7. The method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings according to claim 4, characterized in that, The process includes step 701, which involves synchronously monitoring the intensity of the characteristic spectral lines of the inert protective gas delivered in step 401; and step 702, which involves calculating the change coefficient of optical path transmittance based on the attenuation of the intensity of the characteristic spectral lines of the inert protective gas, and performing amplitude gain compensation on the trace spectral data obtained in step 104 based on the change coefficient.
8. The method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings according to claim 1, characterized in that, In step 104, the opening delay D of the gated window is collected. gate The following logic must be satisfied: , where D gate To collect the opening delay of the gated window, t opt The sampling time when the transient energy level distribution parameters first reach the signal-to-noise ratio characteristic threshold is δt, and δt is the preset system electrical signal transmission delay compensation amount.
9. The method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings according to claim 1, characterized in that, The elemental mapping model in step 105 is established by collecting the spectral evolution curves of standard samples with known magnesium content in the range of 1450℃ to 1500℃; extracting the real-time ratio characteristics of the first band signal intensity and the second band signal intensity to construct a quantitative mapping matrix that excludes blackbody radiation interference.
10. The method for detecting residual magnesium traces in the spheroidization rate of molten iron in injection molding machine template castings according to claim 1, characterized in that, The process includes step 1001, where when the measured evaluation parameter corresponds to a spheroidization rate of less than 90%, a quality feedback signal characterizing the deviation of the molten iron composition is output; and step 1002, where, based on the mass fraction of magnesium, the magnesium content compensation data corresponding to the addition of spheroidizing agent to the molten iron in the injection molding machine template casting is calculated.