Dry-mixed mortar anti-segregation transportation and secondary mixing integrated method

Abstract

The invention discloses an anti-segregation transportation and secondary mixing integrated method for dry-mixed mortar. According to the method, vehicle vibration data are collected in the transportation stage, effective segregation energy is calculated, a segregation accumulation index is generated, when stirring is started, a motor signal is collected, cleaning reconstruction is carried out in combination with bus voltage, and normalized torque is output; and in the control stage, frequency domain decoupling is carried out on the normalized torque, a low-frequency component representing consistency and a high-frequency component representing segregation are separated out, and the flow rate of water injection and the rotating speed of feeding are cooperatively adjusted through double loops in combination with the rheological expected factor and the segregation cumulative index. According to the invention, the correlation between the transportation history and the stirring control is established, the coupling conflict between consistency and uniformity control is solved by using the frequency domain decoupling technology, and feed-forward compensation and adaptive control based on the material state are realized.

Description

Technical Field

[0001] This invention relates to the field of building material processing technology, specifically to an integrated method for preventing segregation in dry-mixed mortar transportation and secondary mixing. Background Technology

[0002] Dry-mixed mortar is a widely used pre-mixed material in construction, mainly composed of aggregates, cementitious materials, and various additives. During transportation from the mixing plant to the construction site, the transport vehicles inevitably generate continuous vibrations. This vibrational energy input causes particle migration in the dry powder material within the storage tank; particles with higher density or smaller particle size tend to sink, while coarse aggregates tend to float, resulting in uneven gradation of the material in the vertical direction.

[0003] When dry powder materials exhibiting segregation enter a continuous mixer, their bulk density and water demand dynamically change over time. Existing continuous dry-mix mortar mixers typically employ open-loop control or closed-loop control based on single current feedback. These devices assume the input dry powder materials are homogeneous and constant, or can only adjust the water injection rate based on the current mixing resistance. However, due to the inherent physical delay in the mixing process, control logic based on real-time feedback often exhibits significant lag. The system only begins to operate when it detects abnormal mixing resistance or substandard discharge conditions, by which time some substandard mortar has already been discharged.

[0004] More importantly, traditional single-feedback control logic struggles to differentiate the causes of changes in mixing resistance. Fluctuations in the mixer motor load can stem from changes in consistency due to variations in the water-to-material ratio, or from changes in aggregate friction caused by material segregation. Existing control systems typically equate increased load with excessively dry material, thus simply increasing the water injection rate. This can easily lead to over-watering when dealing with segregated layers rich in coarse aggregate, causing mortar segregation and bleeding. Furthermore, construction sites often have complex power supply environments, and fluctuations in grid voltage can directly cause drift in motor current or torque signals. Existing equipment lacks signal cleaning mechanisms to address electrical interference, easily misinterpreting voltage fluctuations as load changes, further exacerbating control instability. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an integrated method for preventing segregation during transportation and secondary mixing of dry-mixed mortar. This method solves the technical problem that segregation occurs during the transportation of existing dry-mixed mortar, leading to delayed water-to-material ratio control and unstable output quality in subsequent mixing operations.

[0006] The first aspect of this invention provides an integrated method for preventing segregation during transportation and secondary mixing of dry-mixed mortar, comprising the following steps:

[0007] Step S10: Quantification of material segregation state based on transportation vibration history: During the transportation of dry-mixed mortar, triaxial acceleration signals of the transport vehicles are collected in real time. The collected triaxial acceleration signals are frequency-weighted to calculate the equivalent vibration intensity. A segregation excitation threshold is set; only when the equivalent vibration intensity exceeds the segregation excitation threshold is the excess energy integrated over time to obtain the effective segregation energy. After the mixer and control system are connected, the effective segregation energy is mapped to a segregation accumulation index with values ​​between 0 and 1. The formula for calculating the effective segregation energy is:

[0008]

[0009] In the formula, E seg For effective energy separation, T is the total transport time, and A is... eq (t) represents the equivalent vibration intensity at time t, A th The preset segregation excitation threshold is used, and the max(0,·) function indicates that only positive values ​​are accumulated. This step generates a quantitative index to characterize the degree of material inhomogeneity by quantifying the effective vibration energy during transportation.

[0010] Step S20: Dynamic cleaning and reconstruction of the inverter feedback signal:

[0011] After the mixer is powered on, the raw torque signal of the main mixing motor and the DC bus voltage are simultaneously acquired. The deviation ratio of the real-time acquired DC bus voltage relative to the reference voltage is calculated to generate a voltage compensation coefficient. This voltage compensation coefficient is used to correct the amplitude of the raw torque signal, and the corrected signal is low-pass filtered to remove electromagnetic noise, outputting a normalized torque. This step aims to eliminate the interference of grid voltage fluctuations on the torque observation data.

[0012] Step S30: Start-up prediction based on differential rheological characteristics:

[0013] During the dry operation phase before water injection, the feed motor is controlled to deliver dry powder at a constant low speed, and the upward slope of the load on the main agitator motor is monitored. The deviation between this upward slope and the preset reference slope is calculated, and the deviation is corrected using the segregation cumulative index as a weighting coefficient to generate a rheological prediction factor. This step uses the load change rate of the dry powder to predict the water demand trend of the material in advance.

[0014] Step S40, Dual-loop rheological adaptive control:

[0015] The normalized torque is decoupled in the frequency domain, a cutoff frequency is set, and low-frequency components characterizing the overall consistency of the mortar are extracted using a low-pass filter. Dual-loop control is then executed based on the decoupled components.

[0016] In the fast response loop, the low-frequency component is used as the feedback value and the rheological expectation factor is used as the feedforward quantity. The opening of the electric regulating valve is adjusted in real time through the PID algorithm to change the water injection flow rate, thereby achieving a fast response to the mortar consistency.

[0017] In the slow compensation loop, the real-time variance of the high-frequency component is monitored. When the product of the real-time variance and the segregation cumulative index exceeds the preset instability threshold, the frequency of the feed motor inverter is adjusted to change the feed speed, thereby achieving dynamic compensation for the uniformity of the material.

[0018] Step S50, Anomaly Monitoring and Graded Protection:

[0019] During the control process, the confidence level of the signal and the mechanical load status are periodically verified.

[0020] If the rate of change of the calculated normalized torque exceeds the physical reliability range or a communication interruption is detected, it is determined as a signal failure. The system then cuts off the adaptive control loop and maintains an open-loop control state where the water injection flow rate and feed speed are in a fixed ratio until the end of this operation.

[0021] If the normalized torque exceeds the mechanical safety limit, it is determined to be a mechanical overload, and the following operations are executed in sequence: stop the feed motor, open the water injection valve to perform emergency water injection to reduce the yield stress of the material, and stop the main mixing motor.

[0022] A second aspect of the present invention provides an integrated system for anti-segregation transportation and secondary mixing of dry-mixed mortar, used to perform the above-described method, the system comprising:

[0023] The vibration monitoring module is installed on the transport vehicle to collect vibration data during transportation and generate the segregation accumulation index after calculating the effective segregation energy.

[0024] The signal processing module is connected to the main motor inverter of the mixer. It is used to acquire the raw torque signal and DC bus voltage, perform voltage compensation and filtering algorithms, and output normalized torque.

[0025] The prediction module is activated to calculate the rheological expectation factor for feedforward control during the dry operation phase before formal water injection and mixing by monitoring the load slope and combining it with the segregation accumulation index.

[0026] The central control module is equipped with a dual-loop controller for frequency domain decoupling of the normalized torque. This module adjusts the water injection actuator based on the low-frequency component and rheological expectation factor, and adjusts the feed actuator based on the high-frequency component and segregation cumulative index.

[0027] The safety monitoring module is used to monitor the system's operating status in real time, determine the type of abnormality based on the signal change rate and load amplitude, and execute degraded operation or emergency shutdown protection strategies.

[0028] This invention provides an integrated method for preventing segregation during transportation and secondary mixing of dry-mixed mortar.

[0029] It has the following beneficial effects:

[0030] 1. This invention establishes a data correlation between the transportation and mixing stages by quantifying the effective segregation energy during the transportation process and generating a segregation accumulation index. The control system uses this index as a feedforward variable to predict the degree of material segregation before water injection, thereby overcoming the shortcomings of traditional mixers that can only make lag adjustments based on real-time load, and effectively improving the water-to-material ratio control accuracy of the first batch of discharge.

[0031] 2. This invention utilizes frequency domain decoupling technology to separate the main motor torque signal into a low-frequency component characterizing the overall consistency and a high-frequency component characterizing the disturbance intensity of aggregate particles. Based on this, a dual-loop control strategy is constructed, which uses the low-frequency component to adjust the water injection flow rate and the high-frequency component to adjust the feed speed, thereby achieving independent control of mortar consistency and mixing uniformity, avoiding system oscillations caused by frequent adjustments of a single variable in traditional single-loop control.

[0032] 3. This invention introduces a signal cleaning algorithm based on DC bus voltage to eliminate the interference of on-site power grid voltage fluctuations on torque observation values, ensuring the authenticity of the normalized torque. Combined with anomaly monitoring and graded protection mechanisms, the system can automatically switch to open-loop degradation mode or execute an emergency shutdown when sensor signals fail or mechanical overload occurs, ensuring the continuous and stable operation of the equipment in harsh construction environments. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the system architecture of the present invention;

[0034] Figure 2 This is the overall flowchart of the present invention;

[0035] Figure 3 This is a schematic diagram of the process for constructing the vibration spectrum integral and segregation index during the transportation process according to the present invention;

[0036] Figure 4 This is a logical schematic diagram of the load signal bus voltage normalization preprocessing flow of the present invention;

[0037] Figure 5 This is a timing logic diagram of the differential rheological feature extraction and prediction process during the startup phase of the present invention;

[0038] Figure 6 This is a block diagram illustrating the principle of frequency domain separation dual-loop control for the wet mixing process of the present invention.

[0039] Figure 7This is a logic flowchart of the anomaly monitoring and safety circuit breaker mechanism of the present invention. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example:

[0042] See attached document Figure 1 , Figure 1 This is a schematic diagram of the architecture of an integrated system for anti-segregation transportation and secondary mixing of dry-mixed mortar according to an embodiment of the present invention. The present invention provides a dry-mixed mortar treatment system based on transportation vibration spectrum mapping and dry-wet dual-state rheological verification. The hardware architecture includes a transportation terminal system, an on-site mixing subsystem, and a central control subsystem.

[0043] The transport terminal system uses a transport tanker truck as its carrier. Accelerometers are installed at the rigid connection points of the transport tanker truck. The accelerometers collect vibration acceleration signals during vehicle movement, with sampling frequencies covering the characteristic frequency band of particle seepage and stratification in dry-mixed mortar.

[0044] The transport tanker truck is equipped with an on-board terminal. This terminal is electrically connected to an acceleration sensor, receiving and storing vibration acceleration data. The terminal also has a data transmission interface, allowing it to output historical transport data to external devices during the unloading phase.

[0045] The on-site mixing subsystem consists of a continuous mixing mechanism. The continuous mixer employs an independent drive architecture, including a feeding mechanism and a mixing shaft. The feeding mechanism, driven by a feeding motor, delivers the dry-mixed mortar to the mixing chamber. The mixing shaft, located within the mixing chamber, is driven by a mixing motor.

[0046] The feed motor and the mixing motor are each connected to a frequency converter driver. The frequency converter driver is equipped with a communication interface and outputs motor speed, output current, output torque, and DC bus voltage.

[0047] The on-site mixing subsystem includes a water supply line. The water supply line is equipped with a proportional control valve. The proportional control valve adjusts the flow rate of the liquid phase entering the mixing chamber according to a control signal.

[0048] The core of the central control subsystem is the control unit. The control unit is connected to the variable frequency drive and proportional control valve via a bus. The control unit is equipped with a communication module, which establishes a connection with the on-board terminal and reads historical data.

[0049] The control unit has pre-set data processing logic that calculates and outputs control commands to the proportional control valve and feed motor based on transportation vibration data, real-time torque and voltage data. The system consists of a closed-loop control system that includes historical transportation data input, dry-state physical characteristic verification, and wet-state dual-loop feedback.

[0050] See attached document Figure 2 , Figure 2 This is a general flow chart of a dry-mixed mortar treatment method according to an embodiment of the present invention. The present invention provides an integrated method for preventing segregation during transportation and secondary mixing of dry-mixed mortar, comprising the following steps:

[0051] S10, during transportation, collect the tank vibration acceleration signal and calculate the segregation cumulative index, which characterizes the degree of material stratification.

[0052] S20, during the unloading and mixing stage, real-time acquisition of the DC bus voltage and output torque of the frequency converter driver, and calculation of the normalized torque to eliminate voltage fluctuation interference.

[0053] S30, within the verification window when feeding starts and water supply is not turned on, calculate the time differential slope of the normalized torque, and generate the rheological expectation factor by combining it with the segregation cumulative index;

[0054] S40, during the water injection and mixing stage, adjusts the opening of the proportional control valve and the speed of the feed motor synchronously through a frequency domain separation strategy based on the rheological expectation factor and the real-time normalized torque.

[0055] See attached document Figure 3 , Figure 3 This is a schematic diagram illustrating the process of constructing the vibration spectrum integral and segregation index during transportation.

[0056] In the logistics and transportation of dry-mixed mortar, irregular vibrations caused by vehicle movement are the direct physical cause of particle size segregation in the tank. The physical mechanism mainly manifests as percolation (small particles seeping downwards through the gaps in the skeleton constructed by larger particles under vibrational excitation) and convection (similar to the Brazil berry effect) in which large particles migrate upwards under the influence of vibrational energy. This stratification is not triggered by vibrations across all frequency bands, but is highly correlated with the resonant frequency of the material's packing state. To quantify the cumulative effect of this cause, this embodiment employs a frequency-weighted integral algorithm to construct a segregation accumulation index.

[0057] S101, throughout the entire process from the start of the transport vehicle to its arrival at the unloading site, the on-board triaxial accelerometer operates at a preset sampling frequency f. s Vibration acceleration signals at the tank chassis are continuously collected. Sampling frequency f s The frequency was set to 200Hz to 500Hz to meet the Nyquist sampling theorem's requirements for capturing mid-to-high frequency characteristic signals. The acquired raw signal is denoted as a(t) = [ax (t),a y (t),a z [(t)], corresponding to the acceleration components in the vehicle's driving direction, lateral direction, and vertical direction, respectively. Considering that vibration in the gravitational direction contributes the most to the vertical stratification of particles, this embodiment preferentially selects the vertical component a. z (t) can be used as the main analysis data, or the vector magnitude of triaxial acceleration can be selected. As input data.

[0058] S102 performs frequency domain decomposition and filtering on the acquired acceleration signal. The system converts the time-domain signal into a time-varying spectral density using either a Fast Fourier Transform (FFT) or a Short-Time Fourier Transform (STFT). A digital bandpass filter is then applied to extract the effective frequency band data from 10Hz to 100Hz. This frequency band was selected because vibrations below 10Hz are mostly macroscopic displacements of the vehicle body due to road surface undulations, with the material moving as a whole without relative displacement; high-frequency vibrations above 100Hz attenuate rapidly in bulk materials, making it difficult to propagate to the center of the tank and cause deep segregation. The specific code implementation of the Fast Fourier Transform and digital filtering is a well-known technique in the field of digital signal processing and will not be elaborated upon here.

[0059] S103, Construct a frequency weighting coefficient vector. Mortars with different particle size distributions (gradations) exhibit varying sensitivities to vibration frequencies. The method for determining the preset frequency weighting coefficient η(f) is as follows: In a laboratory environment, the dry-mixed mortar of the target formulation is placed on a standard vibration table, and constant-amplitude vibrations are applied at different single frequencies. The sieve separation rate is measured after a specified time. Using the frequency point with the highest separation rate as a benchmark (normalized to 1.0), a mapping curve between frequency and weighting coefficient is established. In this embodiment, the value of η(f) ranges from 0.1 to 1.5. For example, for standard-graded masonry mortar, its resonance-sensitive zone is typically located between 30Hz and 50Hz. In this range, η≈1.0 is set, and in the non-sensitive zone, η≈0.2 is set.

[0060] S104, Calculate the segregation cumulative index I for a single transport cycle. seg This index represents the total vibration energy experienced by a material throughout its transportation process, after frequency sensitivity correction. In engineering implementation, it is typically calculated using a time-discrete accumulation method, and its physical definition formula is as follows:

[0061]

[0062] In the formula:

[0063] T end The total duration of the transportation process is expressed in seconds (s); f kThis represents the k-th discrete frequency point within the effective frequency band; M represents the total number of frequency points within the effective frequency band, which depends on the window length of the FFT analysis. Indicates time t and frequency f k The vibration acceleration amplitude spectral density at the point is expressed in m / s². 2 or g; η(f) k ) represents frequency f k The corresponding preset weighting coefficients are dimensionless scalars.

[0064] Calculated I seg This is a numerical scalar value stored in the non-volatile memory of the vehicle terminal. This value serves as a threshold criterion for various control logics characterizing the "separation risk level." For example, when I... seg Less than the preset safety threshold I safe When the system determines that the transportation conditions are good, there is no need to initiate subsequent complex rheological compensation; when I seg Greater than I safe At this time, the dry-state verification and dual-loop control in subsequent steps are triggered. Among them, I... safe The specific value is determined by the average value measured under standard road conditions and full load transportation of similar vehicle models. After the vehicle arrives at the construction site and establishes an electrical connection with the continuous mixer, the on-board terminal transmits this value to the mixer control system.

[0065] See attached document Figure 4 , Figure 4 This is a logical diagram of the load signal bus voltage normalization preprocessing flow. In the on-site preparation of dry-mixed mortar, the real-time load torque of the continuous mixer is the core input variable of the feedback control system. Given that construction sites often experience frequent start-ups and shutdowns of large equipment (such as tower cranes and welding machines), leading to grid voltage fluctuations, directly read motor current or torque signals are often mixed with electrical environmental noise. To eliminate spurious load fluctuations caused by electrical factors and ensure that the control system only responds to real mechanical resistance changes caused by changes in material rheological properties (such as viscosity and friction), this embodiment introduces a bus voltage normalization preprocessing step to correct the original signal in real time.

[0066] S201, Establish a real-time data acquisition channel. The central control unit establishes periodic communication with the variable frequency drives (VFDs) that drive the feed motor and the main mixing motor via a fieldbus (such as Modbus-RTU or Profibus-DP). Throughout the entire cycle of the mixer's operation, including the no-load start-up phase and the load mixing phase, the control unit synchronously reads two sets of key data from the VFD's internal registers: one is the original value T of the real-time output torque on the motor side. raw (t), this value is usually expressed as a percentage of rated torque or in Newton-meters (N·m); the second is the real-time value of the inverter's DC bus voltage V. bus(t), the unit is volts (V). To prevent signal glitches and interference, the system performs a step-by-step analysis on the acquired V. bus (t) and T raw (t) Perform a moving average filtering process with a length of N (e.g., N = 5 to 10). The configuration of the above data reading protocol and address mapping are standard technical methods in the field of industrial automation communication. Those skilled in the art can configure them according to the inverter's instruction manual, and will not be elaborated upon here.

[0067] S202 performs mechanism analysis and compensation strategy determination for voltage fluctuation interference. In variable frequency speed control systems, the electromagnetic torque of the motor is closely related to the air gap flux and rotor current. When the grid input voltage drops, causing the DC bus voltage V... bus During the descent, if the frequency converter is in open-loop vector control or V / F control mode, in order to maintain constant output power or overcome mechanical load, its internal regulation circuit will often increase the output current or adjust the voltage vector amplitude, thereby causing the feedback torque reading T to change. raw A rise in voltage that is not due to mechanical causes may occur. Conversely, a false decrease in torque readings may occur when voltage increases. This signal drift caused by voltage fluctuations is easily misinterpreted by the control algorithm as a change in material viscosity. To eliminate this component, the system uses a ratio correction method to standardize the original signal based on the motor's electrical characteristics.

[0068] S203, Calculate the normalized torque T norm (t). The internal arithmetic logic module of the control unit utilizes synchronously acquired V... bus (t) for T raw (t) Perform real-time compensation calculations. The normalized calculation model is as follows:

[0069]

[0070] In the formula: T norm (t) represents the normalized torque after voltage correction, which physically represents the equivalent torque required to drive the current mechanical load under the rated standard voltage, and serves as the sole valid input for subsequent dry-state verification and wet-state control. raw (t) represents the raw, unprocessed output torque value read directly from the frequency converter; V bus (t) represents the DC bus voltage value acquired in real time and filtered; V ref This represents the reference voltage. This value is determined during the equipment's power-on initialization phase. Specifically, in the standby state before the feeding and stirring motors are started, the average DC bus voltage is continuously collected for 1 to 3 seconds as V. ref It is locked until the next system power failure and restart; α represents the voltage-torque correction index, which is a dimensionless correction parameter.

[0071] S204, determine the value of the correction index α. This parameter reflects the sensitivity of the control algorithm of a specific type of motor and inverter to voltage fluctuations. For mixing applications with constant torque load characteristics, the value of α is usually positive. In this embodiment, the method for determining and calibrating α is as follows: During the equipment commissioning phase, the mixer is run under no-load conditions, and the input power supply voltage is adjusted (or the natural fluctuation period of the on-site voltage is utilized), and different V values ​​are recorded. bus T below raw Data; through data fitting, select the values ​​that result in the calculated T. norm The α value that best approximates a constant. As a typical empirical value, for variable frequency systems using sensorless vector control (SLVC), α ranges from 0.8 to 1.2; for systems using V / F control, α ranges from 1.0 to 2.0. In the absence of on-site calibration conditions, the default setting is α = 1.0.

[0072] S205, outputs and caches normalized data. The system will calculate T... norm (t) is stored in a circular shift register for subsequent calculation of the time differential slope or moving average. Through the above processing, regardless of fluctuations in the site voltage, as long as the mechanical load of the mixer remains constant, the T sensed by the system will remain constant. norm This will remain constant, thus ensuring the accuracy of subsequent judgments on material rheological properties based on torque changes.

[0073] See attached document Figure 5 , Figure 5 This is a timing logic diagram of the differential rheological feature extraction and prediction process during the startup phase. When a continuous mixer starts a new cycle of operation, accurately identifying the characteristics of the first batch of material entering the mixing chamber is crucial for precise control of the subsequent water-cement ratio. However, in actual operating conditions, the mixing chamber often contains hardened or semi-hardened wet material remaining from the previous shutdown. These uncontrolled boundary conditions severely interfere with the discrimination method based on absolute torque values. To address this issue, this embodiment proposes a differential rheological feature extraction method based on dynamic loading rate.

[0074] S301 defines the time window for dry-state verification. The time interval from when the central control unit issues a start command and the feed motor begins rotating to convey dry powder until the water supply proportional valve opens to inject water is defined as the verification window Δt. check In terms of logic control, the system forcibly sets the start time t of the feed motor. start With the water valve opening time t water There is a fixed time delay (e.g., 2.0 to 4.0 seconds). Within this window, the new material entering the mixing chamber is in a dry powder state before it is mixed with water, and the load increment it applies to the main stirring shaft reflects purely the tribological properties between the dry powder particles.

[0075] S302, collects and calculates the time differential slope of the normalized torque. In Δt check Within the window, the system continuously reads the normalized torque T of the main stirring motor at a high frequency (e.g., 50Hz). norm (t). Given that the absolute torque value includes the static resistance component generated by residual material within the cavity, which can be considered constant over a short period, the system calculates the dynamic rate of change of torque relative to time (i.e., the loading slope k). dry This static bias is eliminated using the finite difference method.

[0076]

[0077] In the formula: t1 is the moment when the material front end physically reaches the area of ​​the mixing shaft blades after the feeding screw starts. This moment depends on the physical length L of the feeding mechanism and the screw propulsion speed v, i.e., t1≈L / v. In actual equipment, it is usually taken as 0.5 seconds to 1.0 seconds after the start command is issued; t2 is the cutoff time before the water valve opens, usually set to 1.5 seconds to 2.5 seconds after start-up, and it is necessary to ensure that t2 <t water To eliminate the interference of rheological abrupt changes after the addition of the liquid phase; T norm (t1) and T norm (t2) represents the normalized instantaneous torque value at the corresponding moment. To reduce random noise, the arithmetic mean of the values ​​within a 0.1-second window before and after the moment is taken in the actual calculation.

[0078] The physical principle behind this step is that dry powder materials with different gradations have significantly different internal friction angles. If the currently input material is rich in coarse aggregate (such as sand particles with a diameter >1mm), its particles have sharp edges and a large internal friction angle. When it enters the mixing zone, it generates intense mechanical engagement with the blades and the cavity wall, causing the motor load to rise sharply, manifested as a large positive slope k. dry Conversely, if the material is rich in fine powder (such as cement or fly ash), its interparticle air permeability is good, exhibiting fluid-like lubricating characteristics. When entering the mixing zone, the load rises slowly, showing a smaller slope k. dry .

[0079] S303 introduces weighted adjustments based on historical transportation data. It moves away from simply relying on k. dry It may be affected by fluctuations in the feed motor speed, therefore it is necessary to combine it with the segregation cumulative index I obtained in step S10. seg Perform joint verification. Its control logic is based on: I seg The higher the value, the more severe the vibration and stratification of the material during transportation. This indicates a very high probability of extreme coarse aggregate or extremely fine powder accumulation at the current discharge port. In this case, k should be assigned... dry Higher discrimination weights; conversely, if I segA smaller value indicates good material homogeneity, and its actual rheological properties should be close to the standard formulation value. In this case, k should be reduced. dry The magnitude of the correction to the control parameters.

[0080] S304 generates a dimensionless rheological expectation factor λ. The system uses a nonlinear mapping function to transform the physical characteristic quantity k... dry and historical characteristic quantity I seg The results are combined into a single normalization factor for subsequent control. The calculation model is as follows:

[0081]

[0082] In the formula: λ is the rheological expectation factor, with a value range of (-1, 1). λ>0 indicates the dominant trend of coarse aggregate, and λ<0 indicates the dominant trend of fine powder; k ref This serves as a reference loading slope. The calibration method for this value is as follows: With the equipment in a clean, empty cavity state, perform a startup test using standard graded mortar, and record the k values ​​obtained from multiple tests. dry Average value and solidify into system parameters; I seg The cumulative segregation index is calculated in the previous steps; μ is the sensitivity adjustment coefficient, used to adjust the weighting of historical data on the decision result. For high-sensitivity systems, μ ranges from 1.0 to 2.0; for systems with high anti-interference requirements, μ ranges from 0.5 to 1.0.

[0083] S305 outputs the prediction result. The calculated λ value is temporarily stored in the controller's holding register as the initial bias for the "fast loop" feedforward control in the subsequent wet mixing stage. This value is updated each time the equipment restarts feeding and dynamically decays or corrects with real-time status feedback during subsequent continuous operation. Through this process, the system generates compensation parameters for the characteristics of the first batch of materials before the liquid phase is even added.

[0084] See attached document Figure 6 , Figure 6 This is a block diagram illustrating the principle of frequency domain separation dual-loop control in wet mixing processes. In continuous dry-mix mortar mixing, there is a significant time-scale difference between the water supply response and the material feeding response: adjusting the water valve can rapidly change the local water-cement ratio, making it a fast-response variable; while adjusting the solid-phase feed rate requires a delay through the screw conveyor to affect the filling rate within the mixing chamber, making it a slow-response variable. Directly applying strong coupling control to these two variables can easily lead to system oscillations. To address this issue, this embodiment employs a frequency domain separation strategy, constructing a "fast loop" for high-frequency interference and a "slow loop" for trend-based deviations.

[0085] S401 constructs a frequency domain separation control architecture. The central control unit will collect the normalized torque T in real time. norm(t) serves as the main feedback signal. To extract features at different time scales, the system uses a first-order digital low-pass filter to decompose the signal. The low-frequency trend component T... low The calculation of (t) uses an iterative formula: T low [k]=α f ·T norm [k]+(1-α f )·T low [k-1];

[0086] Where α f The filter coefficients range from 0.01 to 0.05. The high-frequency fluctuation component T... high (t) then passes through T high (t)=T norm (t)-T low (t) is obtained. In a physical sense, T high (t) reflects the rheological fluctuations caused by instantaneous component heterogeneity of materials (such as agglomerates), and is suitable for rapid compensation by adjusting the water flow; T low (t) reflects the long-term drift of the average viscosity and filling rate of the material in the cavity, and is suitable for macroscopic intervention by adjusting the feed rate.

[0087] S402 executes fast-loop control: liquid phase flow regulation. The goal of this loop is to quickly smooth out instantaneous load fluctuations caused by material segregation, ensuring consistent discharge consistency. The control algorithm employs a "feedforward + feedback" composite structure. The feedback part is based on a proportional-integral (PI) algorithm, and the regulation objective is to adjust T... norm (t) remains at the set value T target Nearby. The feedforward section introduces the rheological expectation factor λ generated in the preceding steps to pre-compare the base flow rate. Real-time water injection flow command Q water The formula for calculating (t) is as follows:

[0088]

[0089] In the formula: Q base This is the base flow rate, measured in liters per minute (L / min). This value is determined by the product of the current feed motor's set speed and the standard water-cement ratio; K p This is the proportional feedback gain, a dimensionless coefficient typically ranging from 0.5 to 1.5. This coefficient determines the system's response strength to real-time load deviations; T targetThe target wet torque is expressed in Newton-meters (N·m). This value is calibrated experimentally: when the mixer is in optimal mixing condition (discharge consistency meets construction requirements), the normalized average torque of the main mixing motor during stable operation is recorded; γ is the feedforward gain coefficient, used to adjust the influence weight of λ, with a value ranging from 0.1 to 0.3; λ is the rheological expectation factor generated during the dry-state verification stage. Its physical function is: when a large amount of fine powder is predicted (λ<0), the -γ·λ term is positive, instructing the system to increase the water injection volume in the initial stage to compensate for the additional water demand caused by the high specific surface area of ​​the fine powder, preventing "shaft seizure" blockage in the initial stage of mixing; τ decay The decay time constant is used to control the exit speed of the feedforward action, and its value ranges from 10s to 30s.

[0090] S403, Slow Loop Control: Solid Feed Throttling. This loop is triggered only when severe segregation is detected and conventional water injection cannot maintain quality. The physical principle is as follows: When severe segregation occurs (e.g., extreme enrichment of fine powder) leading to a sharp increase in mixing viscosity, simply increasing the water volume will cause a decrease in mortar strength. In this case, by reducing the feed rate, while maintaining a constant main mixing shaft speed, the filling rate of the mixing chamber is effectively reduced, and the number of shearing events and residence time per unit volume of material are increased, thereby improving the dispersion effect. Feed motor speed command R feed The formula for calculating (t) is as follows:

[0091] R feed (t)=R base ·[1-β·Ψ(T low ,I seg )];

[0092] In the formula: R base β is the preset standard feed speed, in revolutions per minute (rpm); β is the maximum throttling coefficient, representing the maximum allowable reduction in speed, for example, 0.3 represents a minimum reduction to 70% of the rated speed; Ψ(·) is the overload judgment function, with a value range of [0,1], and its specific logic implementation is as follows:

[0093]

[0094] Where: H(x) is the unit step function: 1 when x>0, and 0 otherwise. This means that only when the dissociation index I... seg Exceeding the warning threshold I warn This function is activated only when the low-frequency load T is at a certain time; Sat(x) is a saturation function: it takes the value 0 when x < 0, 1 when x > 1, and x when 0 ≤ x ≤ 1. This means that as the low-frequency load T... low Exceeding the upper limit threshold T upper And approaching the limit threshold T limitThe feed rate will decrease linearly.

[0095] S404 implements dual-loop coordinated output. The central control unit synchronously outputs the calculated Q value via a digital-to-analog converter (D / A) interface or communication bus. water (t) The command is sent to the electric proportional control valve to adjust R. feed (t) The command is sent to the feed inverter. To ensure system stability and prevent coupled oscillation between the two control loops, the adjustment period T of the slow loop is... slow Set as fast loop adjustment period T fast N times. In this embodiment, T is set to... fast =100ms, N=10, meaning the feed rate is adjusted once per second. Through this dual separation of the frequency and time domains, the system can effectively address the process challenges posed by severe segregation while ensuring rapid response to changes in the consistency of the output material.

[0096] See attached document Figure 7 , Figure 7 This is a flowchart of the anomaly monitoring and graded protection mechanism. In the harsh electromagnetic and mechanical vibration environments of construction sites, sensor data may experience momentary distortion or communication interruptions. To prevent erroneous feedback signals from misleading the control system and causing issues with mortar strength reliability verification due to excessive water injection, a graded protection logic is implemented. This logic, as a low-level monitoring program independent of the aforementioned control loops, has the highest priority control over the actuators.

[0097] S501 performs physical reliability verification of the input signal. The central control unit uses T... scan Monitoring DC bus voltage V (e.g., 10ms to 20ms) bus (t) and the original torque T raw The rate of change of (t). Based on physical principles, a large-capacity electrolytic capacitor is connected in parallel to the DC bus of the frequency converter, and its voltage change is limited by the RC charging and discharging time constant; at the same time, the stirring system has a large moment of inertia, and its load torque cannot undergo a step change within milliseconds. The system uses a first-order differential operator to calculate the instantaneous increment of the signal and compares it with a preset physical limit threshold:

[0098] |ΔV|=|V bus (t)-V bus (tT scan )|;

[0099] Wherein: the physical limit threshold is 30V to 50V (single-cycle increment); the physical limit threshold T limit The setting is based on the motor's maximum dynamic response capability, and is usually set to 10% to 20% of the rated torque (single-cycle increment).

[0100] If |ΔV|>V is detected limit Or |ΔT|>T limit The system determines that the current data frame is an invalid electromagnetic interference pulse. At this point, the control unit discards the current value, retains the valid value from the previous cycle as the current input, and starts the fault counter C. err If C err The threshold N is exceeded cumulatively within a set time window (e.g., 1.0 second). max If the signal fails 50 times, it is determined that the sensor has a hardware failure or the bus communication has been interrupted, and the system will trigger a "signal failure" state.

[0101] S502, implements emergency protection against mechanical overload. Unlike the aforementioned slow throttling adjustment for segregation, this step primarily addresses the risk of "shaft seizure" caused by sudden large aggregate jamming or extreme water shortage. The system is set with an absolute shutdown threshold T. trip This value is typically set to 150% to 180% of the motor's rated torque. When the normalized torque T is detected... norm (t) continues to exceed T trip When the judgment time t is reached, the operation enable signal of the feed inverter is cut off, the dry powder conveying is physically stopped, and the source of load increment is blocked.

[0102] The electric proportional control valve is forcibly set to 100% full opening to perform an "emergency water injection" operation for 3 to 5 seconds. The physical mechanism of this step is to rapidly reduce the yield stress of the high-viscosity material in the chamber using an excess liquid phase, minimizing the stirring resistance before shutdown to prevent the material from hardening rapidly during shutdown, thereby protecting the gearbox gears and reducing the difficulty of subsequent manual cleaning and restart.

[0103] After the emergency water injection is completed, stop the main mixing motor and report the fault code.

[0104] S503, activate the degraded operation mode of the control strategy. This occurs when a "signal failure" is detected in step S501, or when the onboard data terminal is not connected, causing I... seg In the event of a missing condition, the system automatically disconnects the rheological model-based adaptive control loop and reverts to the "open-loop proportioning control" mode. In degraded mode, the injection flow rate Q... water_fallback Instead of relying on torque feedback, it is based on the current feed motor's set frequency f. feed Perform a linear mapping:

[0105] Q water_fallback =k ratio ·f feed +b offset ;

[0106] In the formula: k ratioThis is the slope of the linear mapping. The method for determining this value is as follows: measure the dry powder conveying capacity of the feed screw conveyor at a unit frequency (Kq / min / Hz), multiply it by the water-cement ratio specified in the standard formula, and obtain the theoretical water injection volume required per unit frequency (L / min / Hz); b offset This is the base flow bias, with an initial value of 0.

[0107] The system alerts the operator via an audible and visual alarm that "adaptive system failure" has occurred. At this point, control is partially transferred to manual operation, and the operator can fine-tune step b manually using the knobs on the control panel. offset The system monitors the output status to correct for deviations. This design ensures that the equipment can maintain basic operational capabilities even in extreme situations such as sensor failure or data link interruption.

[0108] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for integrally transporting and remixing a dry-mixed mortar to prevent segregation, characterized in that, The method comprises the following steps: S10, material segregation state quantification based on transportation vibration history: during the transportation of dry-mixed mortar, three-axis acceleration signals of the transportation vehicle are collected, effective segregation energy is calculated and accumulated based on the signals, and a segregation accumulation index representing the unevenness of the material is generated; S20, dynamic cleaning and reconstruction of frequency converter feedback signal: after the mixer is powered on, the original torque signal of the main mixing motor and the DC bus voltage are collected synchronously, voltage fluctuation interference is eliminated, and normalized torque is output; S30, start-up prediction based on differential rheological properties: during the dry running stage before water injection, the feed load change rate is monitored, and the rheological expectation factor is generated in combination with the segregation accumulation index; S40, double-loop rheological adaptive control: the normalized torque is decoupled in the frequency domain to separate into low-frequency components and high-frequency components; The water injection flow rate is adjusted based on the low-frequency components and the rheological expectation factor, and the feed rotational speed is adjusted based on the high-frequency components and the segregation accumulation index; S50, abnormality monitoring and hierarchical protection: the signal confidence and mechanical load state are periodically checked during the control process, and the adaptive control is maintained, switched to a degraded operation mode, or emergency shutdown protection is performed according to the checking result.

2. The method according to claim 1, wherein the method is characterized by, The process of generating the segregation accumulation index in S10 specifically comprises: The collected three-axis acceleration signals are subjected to frequency weighting processing to calculate the equivalent vibration intensity; A segregation excitation threshold is set, and only when the equivalent vibration intensity exceeds the segregation excitation threshold, the energy of the exceeding part is time-integrated to obtain the effective segregation energy; After the mixer and the control system are connected, the effective segregation energy is mapped to the segregation accumulation index with a value between 0 and 1.

3. The method according to claim 1, wherein the method is characterized by, The calculation formula of the effective segregation energy is: wherein E seq is the effective disaggregation energy, T is the total duration of transport, A eq(t) is the equivalent vibration intensity at time t, A th is the preset disaggregation excitation threshold, max(0, ·) indicates that only positive values are accumulated.

4. The method according to claim 1, wherein the method is characterized by, S20 specifically comprises: The deviation ratio of the real-time collected DC bus voltage relative to the reference voltage is calculated to generate a voltage compensation coefficient; The original torque signal is divided by the voltage compensation coefficient for amplitude correction; The corrected signal is subjected to low-pass filtering to filter out electromagnetic noise to obtain the normalized torque.

5. The method according to claim 1, wherein the method is characterized in that, S30 specifically comprises: The feed motor is controlled to deliver dry powder at a constant low speed, and the rising slope of the main mixing motor load is monitored; The deviation of the rising slope from a preset reference slope is calculated; The deviation is corrected with the segregation accumulation index as a weighting coefficient to calculate the rheological expectation factor for feedforward compensation.

6. The method of claim 1, wherein the method further comprises: The specific way of frequency domain decoupling in S40 is: A cutoff frequency is set, and the low-frequency components representing the overall consistency of the mortar are extracted from the normalized torque through a low-pass filter; The high-frequency components representing the disturbance intensity of the aggregate particles are extracted from the normalized torque through a band-pass filter.

7. The method according to claim 1, wherein the method is characterized by, The double-loop rheological adaptive control of S40 specifically comprises: A fast response loop: a consistency target value is set, the difference between the low-frequency components and the consistency target value is calculated, the rheological expectation factor is combined, and the opening of the electric regulating valve is adjusted through a PID algorithm; A slow response loop: a rheological feedback loop is set, the rheological expectation factor is calculated based on the high-frequency components and the segregation accumulation index, and the rheological feedback loop is adjusted through a PID algorithm. Slow compensation loop: calculate real-time variance of the high-frequency component, when the product of the real-time variance and the segregation accumulation index exceeds a preset instability threshold, adjust the frequency converter frequency of the feeding motor to change the feeding rotation speed.

8. The method of claim 1, wherein the method further comprises: adding a water reducing agent to the dry mix to reduce the water content of the dry mix to less than 0.5% by weight. The condition and processing method for switching to the degraded operation mode in S50 are: Calculate the rate of change of the normalized torque in unit time, and if the rate of change exceeds the physically credible interval or communication interruption is detected, determine that the signal is lost; Cut off the adaptive control loop in S40, and keep the open-loop control state of the fixed proportion between the water injection flow and the feeding rotation speed until the end of the current operation.

9. The method of claim 1, wherein the method further comprises: adding a water reducing agent to the dry mix to reduce the water content of the dry mix to less than 0.5% by weight. The condition and processing method for executing emergency shutdown protection in S50 are: If the normalized torque exceeds the mechanical safety limit, determine that the machine is overloaded; In sequence, stop the feeding motor, open the water injection valve to execute emergency water injection to reduce the yield stress of the material, and stop the main stirring motor.

10. A dry-mixed mortar anti-segregation transportation and secondary mixing integrated system, characterized in that, The system for executing the method according to any one of claims 1 to 9 comprises: A vibration monitoring module installed on the transport vehicle for collecting vibration data and calculating a segregation accumulation index; A signal processing module for collecting motor electrical signals and outputting a normalized torque; A start-up prediction module for performing dry running detection before water injection and generating a rheological expectation factor; A central control module configured with a double-loop controller for cooperatively adjusting the water injection execution mechanism and the feeding execution mechanism based on the normalized torque, the segregation accumulation index, and the rheological expectation factor; and A safety monitoring module for real-time checking of system status and execution of a hierarchical protection strategy.

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