Aluminum die-casting spraying steady-state compensation control method based on multi-dimensional perception and production line

Abstract

This invention relates to the field of automated surface treatment technology for metal die castings, and discloses a steady-state compensation control method and production line for aluminum die casting spraying based on multi-dimensional perception. It utilizes a laser contour sensor and an infrared thermal imager to collect the motion vector and local temperature of the workpiece. Based on the motion vector, a swing model is constructed to derive phase prediction; based on the local temperature, a rheological model is constructed to generate rheological parameters; a pneumatic vibration suppression formula is used to calculate air pressure commands, driving a proportional pressure regulating valve to generate pulsed thrust to lock the phase; based on the air pressure commands and local temperature, a thermal-rate coupling formula is used to calculate speed commands, driving the robot to perform speed compensation; and simultaneously, the electrostatic voltage is adjusted based on the rheological parameters. This invention achieves multi-objective collaborative control of workpiece steady-state maintenance and coating quality compensation by constructing dynamic and thermorheological models, effectively suppressing suspension swaying, eliminating the negative impacts of air pressure fluctuations and uneven heat dissipation on the coating, and ensuring a uniform and dense appearance of the finished product.

Description

Technical Field

[0001] This invention relates to the field of automated surface treatment technology for metal die castings, specifically to a steady-state compensation control method and production line for aluminum die casting spraying based on multi-dimensional sensing. Background Technology

[0002] Aluminum alloy die-cast parts are widely used in the manufacture of automotive components and communication equipment housings due to their lightweight and high strength. Electrostatic powder coating is a key process to ensure the corrosion resistance and appearance quality of these workpieces. In industrial mass production, to meet the needs of continuous operation, workpieces are usually suspended on an overhead conveyor chain by hangers for transfer and coating.

[0003] However, this flexible suspended conveying method suffers from process stability issues in actual operation. Because the connection between the workpiece and the conveyor chain is non-rigid, the workpiece is prone to random swaying and shaking under the impact of acceleration / deceleration vibrations or the airflow from the spray gun during transport. This unstable motion causes real-time fluctuations in the spraying distance between the spray gun and the workpiece surface, resulting in uneven coating thickness distribution. Although existing technologies can use mechanical clamps or bottom limiting devices to forcibly fix the workpiece, this not only increases the labor or equipment costs for loading and unloading and reduces the flexibility of the production line, but also easily leaves missed spray points or contact marks on the workpiece surface due to contact obstruction, making it difficult to meet the requirements for high appearance quality.

[0004] Furthermore, existing automated spraying control equipment typically treats motion control and process parameter control separately. When attempting to address the suspension sway problem, simply using the forming air pressure of the spray gun to generate thrust for workpiece stabilization directly alters the atomization fan width and deposition throughput of the coating. Existing control logic lacks a coordinated adjustment mechanism for this multi-variable coupling relationship and cannot compensate for changes in air pressure in real time for the robot's scanning speed. Therefore, fluctuations in air pressure often lead to changes in the shape of the spray fan, inevitably causing localized deviations in coating thickness when the robot scans at a uniform speed, failing to simultaneously achieve steady-state workpiece control and coating deposition quality.

[0005] Furthermore, aluminum die-cast parts typically possess complex geometries and varying wall thicknesses, resulting in uneven heat capacity distribution across the entire workpiece. During natural cooling after die-casting or pre-treatment drying, temperature gradients form across different areas of the workpiece surface. High-temperature areas lead to a decrease in the resistivity of the powder coating, making it prone to back ionization breakdown and affecting coating smoothness; while low-temperature areas tend to result in low powder application rate or insufficient adhesion. Traditional electrostatic spraying processes often employ constant electrostatic voltage parameters for full surface coverage, failing to adaptively adjust to the localized thermorheological characteristics of the workpiece surface. This results in quality defects in the finished product, such as runs, pinholes, or insufficient thickness in certain areas. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a steady-state compensation control method and production line for aluminum die-casting spraying based on multi-dimensional perception. This solves the problems in existing technologies, such as the spraying distance being affected by the random swaying of the workpiece due to flexible suspension, the lack of a collaborative compensation mechanism for dynamic changes in process parameters leading to uneven film thickness, and the inability to adaptively adjust electrostatic parameters based on differences in workpiece surface temperature, resulting in coating quality defects.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The first aspect of this invention provides a steady-state compensation control method for aluminum die-casting spray coating based on multi-dimensional sensing. The method includes:

[0009] A laser profile sensor and an infrared thermal imager are used to collect distance point clouds and thermal radiation signals of aluminum die-cast workpieces, calculate motion vectors, and map them to generate local temperatures.

[0010] Based on the motion vector, an oscillation model is constructed to obtain phase prediction; based on the local temperature, a rheological model is constructed, a temperature threshold determination is performed, and rheological parameters are generated.

[0011] Based on the motion vector and the phase prediction, the swing direction is determined to generate a direction determination. Combined with the preset position stiffness and preset pneumatic damping, the pneumatic vibration suppression formula is used to calculate the air pressure command including pulse pressure changes, so as to generate a pneumatic repulsive force when the workpiece approaches the spray gun.

[0012] The deformation index is determined based on the air pressure command and the temperature factor is determined based on the local temperature. The speed command for real-time scanning is calculated using the thermal-rate coupling formula to offset the fan-shaped deformation and correct the leveling difference.

[0013] The proportional pressure regulating valve is driven by the air pressure command to achieve phase locking, the industrial robot is driven by the speed command to perform speed compensation, and the electrostatic voltage of the spray gun is adjusted according to the rheological parameters.

[0014] Furthermore, the specific steps of acquiring the distance point cloud and thermal radiation signal of the aluminum die-casting workpiece using a laser contour sensor and an infrared thermal imager include:

[0015] A laser profile sensor installed on the inlet side of the spraying bin is used to continuously scan the aluminum die-casting workpiece moving with the suspended conveyor chain to obtain the distance point cloud relative to the suspension vertical line; the distance point cloud is subjected to time-domain differential processing to calculate the swing angle and swing angular velocity at the current timestamp, and the combination is used to form the motion vector;

[0016] The thermal radiation signal of the workpiece surface is collected simultaneously using an infrared thermal imager installed on the inlet side of the spraying chamber; the thermal radiation signal is mapped onto the digital model grid of the workpiece to generate the discretized local temperature.

[0017] Furthermore, the construction model and generation parameters specifically include:

[0018] Introducing the motion vector and substituting it into the Lagrange dynamics equations, a pendulum or compound oscillation model of the workpiece in a suspended state is constructed; based on the oscillation model, the time is extrapolated backward to calculate the phase prediction when the workpiece reaches the working position.

[0019] Simultaneously, by introducing the local temperature and combining it with the specific heat capacity of the aluminum alloy and the viscosity-temperature curve of the powder coating, a rheological model is constructed, and the relationship between temperature and leveling is established. Based on the rheological model, regions where the local temperature is higher than a set leveling threshold are identified as high leveling regions, regions where the local temperature is lower than a set wetting threshold are identified as low wetting regions, and regions where the local temperature is neither higher than nor lower than the set leveling threshold are identified as standard operating regions. Corresponding benchmark process parameters are matched for the high leveling regions, the standard operating regions, and the low wetting regions, respectively, to generate the rheological parameters.

[0020] Furthermore, the calculation of the air pressure command using the aerodynamic vibration suppression formula specifically includes:

[0021] Extract the oscillation angular velocity from the motion vector; calculate the oscillation angular velocity using a sign function to determine whether the workpiece is currently moving away from or towards the spray gun, thereby determining the oscillation direction; combine the oscillation direction with the phase prediction to generate the direction determination.

[0022] Based on this, the swing angle and swing angular velocity in the motion vector are introduced, and the preset position stiffness, pneumatic damping and reference air pressure are combined to calculate and generate the air pressure command; the air pressure command is used to drive the proportional pressure regulating valve to output a pressure higher than the reference air pressure when the direction determination indicates that the workpiece is close to the spray gun.

[0023] Furthermore, the calculation of the real-time scanning speed command using the thermal-rate coupling formula specifically includes: introducing the air pressure command and calculating the deformation index based on the nonlinear relationship between pressure and fan width; introducing the local temperature and calculating the temperature factor based on the temperature-leveling relationship defined in the rheological model.

[0024] Based on this, the air pressure command, the deformation index, and the temperature factor are introduced, and the speed command is generated by combining the preset reference speed and reference air pressure. The speed command is used to instruct the industrial robot to increase the scanning speed when the fan-shaped area contracts due to the increase of the air pressure command.

[0025] Furthermore, the specific execution of the operation includes: applying the air pressure command to the proportional pressure regulating valve in the air circuit of the spray gun to output pulsed pneumatic thrust and achieve phase locking; applying the speed command to the industrial robot to drive the spray gun to scan the workpiece with a variable speed trajectory and achieve speed compensation; and synchronously adjusting the electrostatic voltage of the spray gun according to the local temperature and the rheological parameters, reducing the voltage in the high flow level area, increasing the voltage in the low wetting area, and maintaining the reference voltage in the standard working area to achieve electrostatic adsorption.

[0026] A second aspect of the present invention provides an aluminum die-casting spray coating production line.

[0027] The production line is based on the above-mentioned steady-state compensation control method for aluminum die casting and spraying based on multi-dimensional perception. Its structure includes a melting furnace, a die casting machine, a conveyor belt, a spraying bin, an industrial robot, and an electrical control cabinet.

[0028] The smelting furnace is located on the feeding side of the die-casting machine, the conveyor belt is located in the discharge direction of the die-casting machine, and a cooling fan is installed on the top of the conveyor belt.

[0029] The spraying chamber is located in the unloading direction of the conveyor belt, and a suspended conveyor chain is provided on the top of the spraying chamber. A laser contour sensor and an infrared thermal imager are installed on the entry side of the spraying chamber.

[0030] The industrial robot is installed inside the spraying chamber, and a spray gun is mounted on the end flange of the industrial robot.

[0031] The electrical control cabinet is communicatively connected to the laser contour sensor, the infrared thermal imager, the servo driver of the industrial robot, and the proportional pressure regulating valve in the spray gun air circuit.

[0032] This invention provides a steady-state compensation control method and production line for aluminum die-casting spraying based on multi-dimensional sensing. It has the following beneficial effects:

[0033] 1. This invention calculates the real-time motion vector and phase prediction of the workpiece, controls the output of the spray gun to produce pulse-type pneumatic repulsive force, and uses the airflow reaction force to suppress and lock the phase of the random sway of the flexible suspended workpiece without the need for additional mechanical fixing devices. This achieves non-contact steady-state control of the workpiece based on the aerodynamic momentum effect, ensuring the stability of the workpiece position during the spraying operation.

[0034] 2. This invention addresses the unavoidable air pressure fluctuations and fan-shaped shrinkage issues caused by pneumatic vibration suppression operations. It couples dynamic control with coating quality control, generating speed compensation commands for the industrial robot in real time based on the deformation index and temperature factor. While performing pneumatic vibration suppression, it dynamically adjusts the scanning speed to offset the film thickness deviation caused by fan-shaped deformation, establishing a multi-objective collaborative control mechanism for heat, air pressure, and speed. This ensures the uniformity of coating deposition under complex airflow disturbances, achieving a synergistic unity between vibration suppression control and spraying quality control.

[0035] 3. This invention addresses the surface temperature differences caused by uneven heat dissipation in aluminum die castings by constructing a rheological model to divide the workpiece surface into a high leveling zone, a standard working zone, and a low wetting zone, and adjusts the electrostatic voltage accordingly. This reduces the risk of back ionization in the high-temperature zone, enhances the powder adsorption force in the low-temperature zone, and improves the overall appearance quality and adhesion of the coating on complex die castings. Attached Figure Description

[0036] Figure 1 This is a flowchart of the steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional perception according to the present invention;

[0037] Figure 2 This is a flowchart illustrating the calculation of vibration suppression control quantities based on aerodynamic momentum effects in this invention.

[0038] Figure 3 This is a flowchart illustrating the generation heat, air pressure, and velocity collaborative compensation strategy of the present invention;

[0039] Figure 4 This is a perspective view of the aluminum die-casting and spraying production line of the present invention;

[0040] Figure 5 This is a schematic diagram of the spraying chamber structure of the present invention.

[0041] The components include: 1. Smelting furnace; 2. Die-casting machine; 3. Conveyor belt; 4. Cooling fan; 5. Spraying bin; 6. Overhead conveyor chain; 7. Laser profile sensor; 8. Infrared thermal imager; 9. Industrial robot; 10. Spray gun; and 11. Electrical control cabinet. Detailed Implementation

[0042] The technical solutions in 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.

[0043] Please see the appendix Figure 1 Appendix Figure 4 and attached Figure 5This invention provides a steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional perception. This method is executed by a controller within the electrical control cabinet 11 and mainly includes:

[0044] Step S1: Real-time acquisition and mapping of multi-dimensional spatiotemporal state data. A laser profile sensor 7 installed on the entry side of the spraying chamber 5 continuously scans the aluminum die-casting workpiece moving into the detection area with the suspended conveyor chain 6, acquiring a distance point cloud of the workpiece surface relative to the suspension vertical line. The distance point cloud is then processed using temporal domain differentiation to calculate the workpiece's position at the current timestamp. The swing angle below and angular velocity of oscillation And combine these two parameters to form a motion vector.

[0045] Simultaneously, an infrared thermal imager 8 installed on the inlet side of the spray booth 5 collects thermal radiation signals from the workpiece surface. These signals are then mapped onto a digital model mesh of the workpiece to generate a local temperature reading. Complete the acquisition of initial state data and establish an initial kinematic and thermodynamic state description of the aluminum die-cast workpiece before it enters the working area.

[0046] Step S2: Construct a suspended oscillation and thermorheological state-space model. Introduce the motion vector output from Step S1, substitute it into the Lagrange dynamics equations, and construct a simple pendulum or compound oscillation model of the workpiece in a suspended state, calculating the phase prediction. Introduce the local temperature output from Step S1. A rheological model was constructed by combining the specific heat capacity of aluminum alloy with the viscosity and temperature curves of powder coating. Based on the rheological model, the workpiece surface was divided into a high leveling region and a low wetting region, and rheological parameters containing the reference process parameters of each region were generated.

[0047] Step S3: Calculate the vibration suppression control quantity based on aerodynamic momentum effect. Extract the oscillation angular velocity from the motion vector output in step S1. Through symbolic functions Determine the current swing direction of the workpiece and generate a direction determination, where the direction away from the spray gun is defined as positive and the direction closer to it is negative.

[0048] Introducing motion vectors (including) and And direction determination, combined with preset position stiffness With aerodynamic damping The results were obtained through calculation using aerodynamic vibration suppression formula. Air pressure command at any time When the workpiece swings closer to the spray gun 10, a pressure value capable of generating a repulsive force is generated. The pneumatic vibration suppression formula is as follows:

[0049] ;

[0050] In the formula: for The air pressure command at any time, that is, the target pressure value output by the controller to the proportional pressure regulating valve of the spray gun 10; The reference air pressure is the preset constant air pressure value that meets the standard atomizing fan width requirements; This is a sign function used to determine the swing direction. It is defined as the direction where the workpiece is away from the spray gun by 10, which returns +1; and the direction where the workpiece is closer to the spray gun is negative, which returns -1. for The angular velocity of the workpiece at any given moment is derived from the motion vector; For positional stiffness, a preset proportional constant is used to define the gain weight of angular deviation on aerodynamic thrust; This is the absolute value operator, which takes the non-negative value of the number within the parentheses. for The swing angle of the workpiece at any given moment is derived from the motion vector; For aerodynamic damping, a preset proportional constant is used to define the gain weight of angular velocity on aerodynamic damping force.

[0051] Step S4: Generate a coordinated compensation strategy for heat, air pressure, and velocity. Introduce the air pressure command output from step S3. Based on the nonlinear relationship between pressure and fan width, the deformation index is calculated. Introduce the local temperature output from step S1. Based on the rheological model in step S2, the temperature factor is calculated. .

[0052] Introducing air pressure command Deformation index and temperature factor The speed command for real-time scanning is obtained by calculating using the thermal-rate coupling formula. The optimal compensation speed for the robotic arm is calculated to eliminate the influence of fan-shaped deformation caused by air pressure changes, and corrections are made based on temperature data. The thermal-rate coupling formula is as follows:

[0053] ;

[0054] In the formula: for The speed command at any given moment, that is, the target value of the end-effector movement speed output by the controller to the industrial robot 9; The reference speed is the standard spraying speed set under the reference air pressure. The deformation index is a dimensionless constant that characterizes the nonlinear scaling relationship between the effective width of the spray gun fan and air pressure. This is the temperature factor, a dimensionless coefficient determined based on the current local temperature. This represents the local temperature, indicating the real-time temperature value of the currently coated area on the workpiece surface.

[0055] Step S5: Perform multi-target collaborative spraying operation. The air pressure command output in step S3... The proportional pressure regulating valve acting in the air circuit of the spray gun 10 outputs pulsed pneumatic thrust, which pushes the workpiece back to the equilibrium position when it swings to a specific phase, thus achieving phase locking.

[0056] The speed command output in step S4 This is applied to industrial robot 9, driving spray gun 10 to scan the workpiece with a variable-speed trajectory, achieving speed compensation. Based on local temperature... The rheological parameters output in step S2 are used to synchronously adjust the electrostatic voltage of the spray gun 10 to achieve electrostatic adsorption. Finally, a uniform spraying operation is completed under controlled workpiece oscillation.

[0057] Step S1: In order to accurately reconstruct the initial state of the aluminum die-casting workpiece before the spraying operation, the real-time acquisition and mapping of multi-dimensional spatiotemporal state data can be achieved through the following sub-steps S101 to S104.

[0058] Step S101: The aluminum die-casting workpiece that moves into the detection area with the suspended conveyor chain 6 is continuously scanned using the laser profile sensor 7 installed on the entry side of the spraying chamber 5.

[0059] A laser profile sensor 7 (e.g., a 2D line laser profiler employing the principle of laser triangulation) projects a laser beam onto the workpiece surface at a preset high sampling frequency and receives the reflected light signal. The sampling frequency (e.g., 1 kHz to 5 kHz) is set based on the workpiece's moving speed on the suspended conveyor chain 6 and the required phase capture accuracy. The laser profile sensor 7 converts the received light signal into depth information, generating a distance point cloud of the workpiece surface relative to the suspension vertical line.

[0060] Among them, the suspended plumb line refers to the vertical baseline formed by the traction of gravity on a flexible hanger when it is stationary and without external force. Distance point cloud is a set of spatial coordinates. The dataset reflects the physical distance of each point on the workpiece surface relative to the laser profile sensor 7 at the current moment. The specific signal processing procedures for laser triangulation and point cloud generation are well-known technologies in this field and will not be elaborated here.

[0061] Step S102: Perform temporal domain differentiation on the distance point cloud obtained in step S101 to calculate the workpiece at the current timestamp. The swing angle below and angular velocity of oscillation And combine these two parameters to form a motion vector.

[0062] The controller inside electrical control cabinet 11 first extracts features from the distance point cloud, identifies the geometric center of the workpiece or a specific marker point, and calculates the horizontal displacement of that feature point relative to the suspension plumb line. This is done using inverse trigonometric function relationships (e.g., ,in This is the horizontal displacement. (Equivalent pendulum length of the flexible fixture) is used to calculate the current swing angle of the workpiece. .

[0063] Subsequently, the controller measures the oscillation angle over a continuous time series. Numerical differentiation (e.g., using the finite difference method) is performed to calculate the rate of change of the oscillation angle with time, thereby obtaining the oscillation angular velocity. To eliminate the interference of measurement noise on differential calculations, filtering algorithms (such as Kalman filtering or moving average filtering) are typically introduced to smooth the raw angle data. Finally, the filtered data is... and It is encapsulated as a two-dimensional array or structure, i.e., a motion vector, as the input for subsequent dynamic modeling.

[0064] Step S103: Simultaneously use the infrared thermal imager 8 installed on the entry side of the spraying chamber 5 to collect the thermal radiation signal of the workpiece surface.

[0065] An infrared thermal imager 8 (e.g., an uncooled focal plane array thermal imager) is positioned adjacent to the laser profile sensor 7, with its field of view covering the area through which the workpiece passes. The infrared thermal imager 8 receives the infrared radiation energy emitted from the surface of the aluminum die-cast workpiece and converts it into a corresponding electrical signal, i.e., a thermal radiation signal. During the acquisition process, the controller corrects the thermal radiation signal based on the surface emissivity characteristics of the aluminum alloy material. The surface emissivity (e.g., 0.2 to 0.3) is a parameter that is experimentally determined in advance based on the material composition and surface roughness of the workpiece and stored in the controller.

[0066] Step S104: Map the thermal radiation signal obtained in step S103 onto the digital model mesh of the workpiece to generate a local temperature. .

[0067] The controller pre-stores a standard 3D digital model (e.g., a CAD mesh model) of the aluminum die-cast workpiece. Using image registration technology, the controller employs geometric contour information acquired by the laser contour sensor 7 as constraints to spatially align the 2D thermal image acquired by the infrared thermal imager 8 with the 3D digital model. Through coordinate transformation, the temperature value of each pixel in the thermal image is projected onto the corresponding mesh node on the surface of the digital model.

[0068] The generated local temperature A discretized temperature field dataset describes the temperature distribution of different regions on the workpiece surface (such as thick-walled areas, thin-walled heat sink areas, and deep cavity areas) at the current moment. This dataset contains temperature values ​​and their corresponding spatial location indices, thus providing local physical state data for subsequent coordinated control of heat, pressure, and velocity.

[0069] Step S2, constructing the suspended oscillation and thermorheological state space model, can be specifically implemented through the following sub-steps S201 to S203.

[0070] Step S201: Introduce the motion vector output in step S102, substitute it into the Lagrange dynamics equation, construct a single pendulum or compound oscillation model of the workpiece in the suspended state, and calculate the phase prediction.

[0071] The controller inside electrical control cabinet 11 reads data including the swing angle. and angular velocity of oscillation The motion vector. The controller has a pre-set Lagrange dynamics equation describing the suspended conveyor chain 6 and the flexible fixture. This equation is based on the difference between the equipment's kinetic energy (determined by the oscillation speed) and potential energy (determined by the change in height in the gravitational field), and describes the equipment's motion in a generalized coordinate system.

[0072] The controller uses a numerical integration algorithm (such as the Runge-Kutta method) to solve the differential equation at the current time step. The motion vector is used as the initial condition, and the time is extrapolated backward. When predicting the movement of the workpiece from the detection position of the laser contour sensor 7 to the working position of the industrial robot 9 (i.e., The swing state at a given moment.

[0073] The calculated phase prediction specifically includes the swing angle, angular velocity, and the phase point of the swing cycle at the predicted time (e.g., the point of maximum amplitude in the forward direction, the equilibrium position, or the point of maximum amplitude in the reverse direction). This prediction process compensates for the time lag caused by the spatial distance between the sensor installation location and the actual spraying station.

[0074] Step S202: Introduce the local temperature output from step S104. A rheological model was constructed by combining the specific heat capacity of aluminum alloy with the viscosity and temperature curves of powder coating.

[0075] The controller retrieves a pre-stored material property database, which includes the specific heat capacity parameters of the aluminum alloy substrate and the rheological property curves of the powder coating. The rheological property curves describe the nonlinear relationship between the dynamic viscosity of the powder coating and temperature during the melting process (typically showing a trend of viscosity first decreasing and then increasing with increasing temperature, with the lowest viscosity range corresponding to the optimal leveling properties).

[0076] The controller retrieves a pre-stored material property database, including the specific heat capacity parameters of the aluminum alloy substrate and the rheological property curves of the powder coating. The rheological property curves describe the nonlinear relationship between the dynamic viscosity of the powder coating and temperature during the melting process. A rheological model is established to discretize the local temperature of the workpiece surface. The correspondence between the coating viscosity value and the curing kinetics.

[0077] The determination of the material thermophysical parameters and viscosity curves can be obtained by those skilled in the art through differential scanning calorimetry (DSC) or rotational rheometer testing, which are well-known techniques in the field and will not be elaborated here.

[0078] Step S203: Based on the rheological model established in step S202, the workpiece surface is divided into a high leveling region and a low wetting region, and rheological parameters containing the reference process parameters of each region are generated.

[0079] The controller performs threshold determination on the full-field temperature data in the rheological model.

[0080] Areas with localized temperatures exceeding a set leveling threshold are marked as high leveling zones. The set leveling threshold is based on the lowest melt viscosity temperature of the powder coating (e.g., for typical polyester powder coatings, this threshold can be set to 120°C to 140°C). Within this temperature range, the powder coating has fluidity and is easy to fill microscopic irregularities, but it is also prone to sagging.

[0081] Areas with localized temperatures below a set wetting threshold are marked as low-wetting zones. The set wetting threshold is based on the glass transition temperature or initial melting temperature of the powder coating (e.g., set to 80°C to 90°C). Within this temperature range, powder particles cannot fully melt and wet the substrate, resulting in decreased adhesion or increased coating porosity.

[0082] The standard operating zone is defined as the area where the local temperature falls between the set leveling threshold and the set wetting threshold (i.e., set wetting threshold ≤ local temperature ≤ set leveling threshold). Within this temperature range, the powder coating is in an ideal curing window, enabling the formation of a uniform and stable coating.

[0083] After the region division is completed, the controller matches the corresponding rheological parameters for each region. The rheological parameters are a set of parameters that include a reference voltage correction factor and a reference powder supply correction factor.

[0084] For example, for high flow level regions, a lower reference voltage correction factor is set in the rheological parameters to prevent back ionization breakdown at high temperatures; for low wetting regions, a higher reference voltage correction factor is set in the rheological parameters to enhance electrostatic adsorption; for standard operating regions, the reference voltage correction factor is set to a standard value (e.g., 1.0) in the rheological parameters to maintain the preset normal electrostatic voltage output. These rheological parameters will serve as the basis for electrostatic voltage adjustment in subsequent step S5.

[0085] See attached document Figure 2 Step S3, calculating the vibration suppression control quantity based on the aerodynamic momentum effect, can be specifically implemented through the following sub-steps S301 to S303. This step generates a reverse thrust by adjusting the forming air pressure output by the spray gun 10, thereby suppressing the random swaying of the workpiece.

[0086] Step S301: Extract the oscillation angular velocity from the motion vector output in step S102. Through symbolic functions Determine the current swing direction of the workpiece and generate a direction determination.

[0087] The controller inside electrical control cabinet 11 reads real-time motion vector data from memory. To determine the timing and direction of applying aerodynamic thrust, the controller monitors the oscillation angular velocity. Perform symbol extraction.

[0088] In this embodiment, the direction in which the workpiece moves away from the spray gun 10 is defined as the positive direction. The direction in which the workpiece is closer to the spray gun 10 is the negative direction. ).

[0089] when When the value returns to -1, it indicates that the workpiece is moving towards the spray gun 10. At this time, applying pneumatic thrust can effectively counteract the kinetic energy of the workpiece, thus providing a damping effect; when When the value returns to +1, it indicates that the workpiece is moving away from the spray gun, and at this time, it is usually not necessary to apply additional thrust or maintain the reference pressure.

[0090] Step S302: Introduce the motion vector output from step S102 (including...) and The direction determination output from step S301, combined with the preset position stiffness, is used to determine the direction. With aerodynamic damping The calculation is performed using aerodynamic vibration suppression formulas.

[0091] The controller calculates the additional air pressure required to push the workpiece back to its equilibrium position or dissipate its oscillation energy based on the current oscillation state of the workpiece. This is calculated using the following pneumatic vibration damping formula. Air pressure command at any time :

[0092] ;

[0093] In the formula: for The air pressure command at any time, that is, the target pressure value output by the controller to the proportional pressure regulating valve of the spray gun 10; The reference air pressure is a preset constant air pressure value that meets the standard atomization fan width requirements. The reference air pressure (e.g., 0.2MPa to 0.4MPa) is preset according to the specifications of the spray gun 10 and the atomization characteristics of the powder coating. This is a sign function used to determine the swing direction. It is defined as the direction where the workpiece is away from the spray gun by 10, which returns +1; and the direction where the workpiece is closer to the spray gun is negative, which returns -1. for The angular velocity of the workpiece at any given moment is derived from the motion vector; For position stiffness, a preset proportional constant is used to define the gain weight of angular deviation on aerodynamic thrust. This position stiffness (e.g., 0.5MPa / rad to 1.5MPa / rad) is determined through on-site commissioning based on the workpiece mass, suspension length, and required position recovery speed. This is the absolute value operator, which takes the non-negative value of the number within the parentheses. for The swing angle of the workpiece at any given moment is derived from the motion vector; For aerodynamic damping, a preset proportional constant is used to define the gain weight of angular velocity on aerodynamic damping force. The aerodynamic damping (e.g., 0.1 MPa·s / rad to 0.5 MPa·s / rad) is set according to the requirements for vibration decay rate.

[0094] The physical meaning of this formula is: when the workpiece approaches the spray gun ( (If it is negative), the second term of the formula becomes positive, making the output air pressure... At the reference pressure Based on the above, the increase depends on the current swing amplitude (position term) and swing speed (velocity term), thus generating a pulse thrust that dynamically changes with the swing state;

[0095] When the workpiece moves away from the spray gun ( (Positive), the controller maintains the reference air pressure or adjusts it in the opposite direction (depending on the specific control strategy; usually, to ensure basic atomization, a setting is made). The lower limit is not lower than the minimum pressure required to maintain atomization.

[0096] Step S303: Output the result calculated in step S302. Time pressure command .

[0097] The controller will calculate the digital quantity The pneumatic force is converted into a corresponding analog voltage signal (e.g., 0-10V) or current signal (e.g., 4-20mA) and sent via the I / O interface to a proportional pressure regulating valve connected in series with the forming air pipeline of the spray gun 10. This pneumatic command drives the valve core of the proportional pressure regulating valve to adjust the gas pressure flowing through the forming air outlet of the spray gun 10 in real time, generating the required vibration damping thrust. This process is continuous and real-time, ensuring that the pneumatic thrust changes closely with the phase change of the workpiece's oscillation.

[0098] See attached document Figure 3 Step S4, which generates a coordinated compensation strategy for heat, air pressure, and velocity, can be implemented through the following sub-steps S401 to S404. This step is used to offset the impact of air pressure fluctuations caused by aerodynamic vibration suppression in step S3 on the coating quality, and to integrate the correction of coating leveling properties by thermodynamic state.

[0099] Step S401: Introduce the air pressure command output in step S303. Based on the nonlinear relationship between pressure and fan width, the deformation index is calculated. .

[0100] The controller inside electrical control cabinet 11 receives a pneumatic command for vibration damping. In the spraying process, the main function of the forming air is to control the shape (fan width) of the powder cloud at the spray gun exit. When the forming air pressure is increased to suppress workpiece swaying, the powder cloud will be subjected to stronger lateral compression, resulting in a narrower spray fan width and an increase in the flux density per unit area.

[0101] If the robotic arm maintains its original moving speed, it will inevitably lead to excessively thick coatings in certain areas of the workpiece. The controller stores a pressure-fan width characteristic curve describing this spray gun model. The controller then uses this characteristic curve and the current... The deformation index characterizing the degree of sector compression was calculated. Deformation index It is a dimensionless constant (e.g., 0.5 to 1.2), the magnitude of which depends on the geometry of the nozzle and the design of the airflow guide orifice, and is usually provided by the spray gun manufacturer or determined through offline spraying experiments.

[0102] Step S402: Introduce the local temperature output from step S104. Based on the rheological model in step S202, the temperature factor is calculated. .

[0103] The controller determines the temperature factor of the current spraying area based on the temperature-leveling relationship defined in the rheological model. This factor is used to correct for variations in deposition efficiency caused by temperature differences.

[0104] For example, in high-leveling zones (higher temperatures), the powder melts quickly, making sagging more likely. In this case, it's necessary to appropriately increase the scanning speed to reduce the thickness of a single coat. The value will be set to be greater than 1 (e.g., 1.1); in low-wetting areas (lower temperatures), the powder adhesion rate is low, requiring a reduction in scanning speed to increase powder accumulation. The value will be set to be less than 1 (e.g., 0.9). The specific numerical mapping relationship is stored in the controller's lookup table.

[0105] Step S403: Introduce the air pressure command output in step S303. The deformation index output in step S401 and the temperature factor output in step S402 The calculation is performed using the thermal-rate coupling formula.

[0106] The controller uses the above parameters to calculate in real time the scanning speed that the robotic arm's end effector should execute, ensuring that the final coating thickness remains uniform despite the combined disturbances of fan-shaped deformation and temperature changes. The specific calculation is based on the following thermal-rate coupling formula:

[0107] ;

[0108] In the formula: for The speed command at any given time is the target value of the end-effector movement speed output by the controller to the industrial robot 9, which changes dynamically over time. The reference speed is the standard spraying speed set under the reference air pressure. This reference speed (e.g., 0.5 m / s to 1.2 m / s) is a process constant preset according to the production cycle requirements and the standard film thickness (e.g., 80 micrometers). The deformation index is a dimensionless constant that characterizes the nonlinear scaling relationship between the effective width of the spray gun fan and air pressure. This is the temperature factor, a dimensionless coefficient determined based on the current local temperature. This represents the local temperature, indicating the real-time temperature value of the currently coated area on the workpiece surface.

[0109] The formula expresses the following control logic: when the air pressure... When the fan width narrows due to the increase (for vibration suppression), the ratio term is greater than 1, and the command speed... As the temperature factor increases, the robotic arm accelerates through the region, thus offsetting the increasing film thickness caused by the fan-shaped contraction; simultaneously, the temperature factor... As a gain factor, the speed is fine-tuned to adapt to the leveling requirements of different temperature zones.

[0110] Step S404: Output the real-time scanning speed command calculated in step S403. .

[0111] The controller sends the calculated speed command to the servo drive of the industrial robot 9 via a fieldbus (such as EtherCAT or Profinet). This command has high priority, ensuring that the industrial robot 9 can achieve millisecond-level speed change response, thereby achieving precise synchronization between the spraying trajectory and the pneumatic vibration damping action in space.

[0112] Step S5, performing multi-target collaborative spraying operation, can be implemented through the following sub-steps S501 to S503.

[0113] This step transforms the various control commands calculated by the controller in the electrical control cabinet 11 into the actual actions of the physical equipment, and synchronously completes pneumatic vibration suppression, speed compensation and electrostatic adjustment on the same time axis, thereby realizing multi-objective collaborative control of the spraying process.

[0114] Step S501: The air pressure command output in step S303 The proportional pressure regulating valve acting in the air circuit of the spray gun 10 outputs pulsed pneumatic thrust, which pushes the workpiece back to the equilibrium position when it swings to a specific phase, thus achieving phase locking.

[0115] Electrical control cabinet 11 will send pneumatic commands in digital form. The signal is converted into an analog control signal via a digital-to-analog converter (D / A converter), which drives a proportional pressure regulating valve connected in series in the forming air pipeline. The proportional pressure regulating valve adjusts the opening degree of the valve port in real time according to the signal amplitude, so that the air pressure ejected from the forming air outlet of the spray gun 10 changes in accordance with the command.

[0116] When the workpiece swings closer to the spray gun 10, the air pressure command... Including the increased pressure component, the forming air velocity increases sharply, applying aerodynamic thrust (reverse momentum) to the workpiece surface. This thrust acts as a non-contact damping force, consuming the workpiece's swing kinetic energy and forcing the workpiece to rebound or decelerate before reaching its maximum swing angle, thereby limiting the workpiece's swing amplitude to a preset process allowable range (e.g., swing amplitude less than ±5 degrees), thus locking the workpiece's swing phase.

[0117] Step S502: The speed command output in step S404 is... It is applied to industrial robot 9, driving spray gun 10 to scan workpiece with variable speed trajectory to achieve speed compensation.

[0118] The controller transmits speed commands via a real-time industrial Ethernet bus. The speed command is sent to the servo controller of the industrial robot 9. Based on this speed command, the inverse kinematics module of the industrial robot 9 dynamically plans the angular velocity of each joint axis, driving the end spray gun 10 to move along the preset spraying trajectory.

[0119] Due to speed command The system incorporates the effects of air pressure changes on the spray pattern width and temperature correction for leveling. Therefore, when pneumatic vibration suppression causes the spray pattern to shrink, the industrial robot 9 instantly accelerates through the corresponding area to prevent excessive paint buildup. Conversely, when the air pressure returns to its baseline value, the robot resumes its baseline speed. This variable-speed scanning strategy ensures that the powder deposition amount (film thickness) per unit area remains uniform even under severe airflow disturbances, effectively offsetting process deviations caused by vibration suppression.

[0120] Step S503: Based on local temperature The rheological parameters output in step S203 are used to synchronously adjust the electrostatic voltage of the spray gun 10 to achieve electrostatic adsorption.

[0121] While the robotic arm performs variable-speed scanning, the controller sends a voltage adjustment command to the high-voltage electrostatic generator built into the spray gun 10. The adjustment logic is executed based on the mapping relationship in the rheological parameters:

[0122] For surface areas marked as high leveling zones, the powder resistivity decreases due to the high temperature (e.g., above 120°C), which can easily lead to back ionization and damage the coating appearance. The controller lowers the electrostatic voltage to a low voltage range (e.g., 40kV to 60kV) to suppress back ionization and promote leveling by using thermal melting.

[0123] For surface areas marked as low wetting zones, due to their low temperature (e.g., below 90°C) and poor powder mechanical adhesion, the controller increases the electrostatic voltage to a high-voltage range (e.g., 80kV to 100kV) to increase powder uptake and cohesion by utilizing a strong electrostatic field.

[0124] After the above-mentioned collaborative spraying operation is completed, the aluminum die-cast workpiece with uniform coating thickness and good adhesion continues to run on the suspended conveyor chain 6, leaving the spraying chamber 5 and entering the downstream curing component. In the curing component, the workpiece is heated and kept at a constant temperature, and the powder coating on the surface undergoes melting, leveling, and cross-linking curing reactions, ultimately forming a dense protective film for the finished product.

[0125] Please see the appendix Figure 4 and attached Figure 5 The present invention also provides an aluminum die-casting spraying production line, which mainly consists of a hot forming section, a logistics conveying section, an intelligent spraying section, and a curing post-treatment section. Each section works collaboratively through physical connection and information interaction.

[0126] In the hot forming section, the melting furnace 1 is set as the starting equipment of the production line, used to heat and melt solid aluminum alloy raw materials into liquid metal.

[0127] The die-casting machine 2 is located downstream of the melting furnace 1. Its feed inlet is connected to the melting furnace 1 via a trough or an automatic feeder, and is used to receive molten metal and perform high-pressure injection molding. The die-casting machine 2 typically adopts a horizontal cold chamber die-casting machine structure, with a discharge port located below or on the side.

[0128] The conveyor belt 3 is arranged below the discharge port of the die-casting machine 2 to receive the high-temperature aluminum die-casting workpieces that fall out of the die-casting mold and transport them horizontally to the next process.

[0129] Cooling fans 4 are mounted on the upper or side supports of the conveyor belt 3, with their air outlets directed at the flow of workpieces on the conveyor belt 3. The number and airflow configuration of the cooling fans 4 are set according to the heat dissipation requirements of the workpieces, and are used to force-cool the workpieces during the conveying process, so that the workpieces form a specific residual temperature field before reaching the spraying process.

[0130] The logistics conveying section mainly consists of an overhead conveyor chain 6. The overhead conveyor chain 6 adopts an elevated track structure, running above the pretreatment area, the spraying chamber 5, and the curing components. Flexible hangers are installed at equal intervals below the overhead conveyor chain 6 to suspend the aluminum die-cast workpieces to be sprayed.

[0131] The pretreatment component is located at the front end of the overhead conveyor chain 6, upstream of the spraying chamber 5. It integrates a high-pressure cleaning spray component and a phosphating treatment tank, which are used to remove oil and chemical conversion film from the surface of the passing workpieces.

[0132] The core of the intelligent spraying section is the spraying chamber 5. The spraying chamber 5 is a closed or semi-closed cavity structure designed to provide a clean and stable airflow environment for spraying operations. The overhead conveyor chain 6 passes through the top of the spraying chamber 5, moving the workpiece along the longitudinal axis of the spraying chamber 5.

[0133] Both the laser profile sensor 7 and the infrared thermal imager 8 are installed on the entry side of the spraying chamber 5 (i.e., at the entrance where the workpiece enters the spraying chamber 5). The laser profile sensor 7 is fixed by a rigid bracket, and its scanning plane is perpendicular to the movement trajectory of the workpiece, used to continuously collect the distance change of the workpiece relative to the suspension vertical line.

[0134] The infrared thermal imager 8 and the laser contour sensor 7 are arranged side by side or integrated on the same detection bracket, and their field of view covers the surface of the workpiece to collect the three-dimensional thermal radiation distribution of the workpiece.

[0135] Inside the spraying chamber 5, there is an industrial robot 9. The industrial robot 9 adopts a dual-station staggered arrangement structure, that is, the first robot and the second robot are staggered by a preset distance (e.g., 2 to 4 meters) along the movement direction of the suspended conveyor chain 6, and are located on both sides of the workpiece movement trajectory.

[0136] This staggered layout allows the two robots to work independently on the front and back of the workpiece, respectively, and the aerodynamic damping airflows they apply do not interfere with each other.

[0137] The spray gun 10 is mounted on the end flange of the industrial robot 9, and an electro-proportional pressure regulating valve is connected in series on the forming air input pipeline of the spray gun 10. As a key hardware component for implementing pneumatic vibration damping, the electro-proportional pressure regulating valve can receive electrical signals and linearly adjust its output air pressure at the millisecond level, thereby generating variable pneumatic thrust at the forming air outlet of the spray gun 10.

[0138] The post-curing treatment section is located downstream of the spraying chamber 5. The curing assembly is located on the conveying path after the outlet of the spraying chamber 5, and typically adopts a tunnel-type hot air circulating oven or infrared radiation heating furnace structure. The suspended conveyor chain 6 runs through the interior of the curing assembly, allowing the sprayed workpiece to complete the melting, leveling, and cross-linking curing of the powder as it passes through.

[0139] The electrical control cabinet 11 serves as the control center for the entire production line and is located in an area that facilitates operation and maintenance. The electrical control cabinet 11 houses a controller (such as an industrial PC or high-performance PLC) that integrates a dynamics calculation module, a rheological analysis module, and a multi-objective collaborative control algorithm.

[0140] The electrical control cabinet 11 establishes bidirectional communication connections with the laser profile sensor 7, the infrared thermal imager 8, the servo driver of the industrial robot 9, and the electrical proportional pressure regulating valve in the air circuit of the spray gun 10 via an industrial fieldbus (such as EtherCAT, Profinet, or Modbus TCP).

[0141] Among them, the laser contour sensor 7 and the infrared thermal imager 8 serve as input nodes, transmitting status data to the electrical control cabinet 11 in real time; the industrial robot 9 and the electric proportional pressure regulating valve serve as execution nodes, receiving speed commands and air pressure commands from the electrical control cabinet 11.

[0142] In addition, the electrical control cabinet 11 also interacts with the control units of the die-casting machine 2, the conveyor belt 3, and the curing components.

[0143] The aluminum die-casting spraying steady-state compensation control method and production line based on multi-dimensional perception provided in this invention realizes high-precision spraying of non-rigid suspended workpieces by establishing a coupled control model of dynamics and thermorheology.

[0144] In the production process, after the aluminum alloy is formed by the melting furnace 1 and the die-casting machine 2, it is conveyed by the conveyor belt 3 and cooled by the cooling fan 4 in a controlled manner, forming a workpiece with a specific residual heat field to be sprayed. When the workpiece enters the spraying chamber 5 with the suspended conveyor chain 6, the laser contour sensor 7 and the infrared thermal imager 8 synchronously collect its swing displacement and surface temperature distribution, and transmit the data to the electrical control cabinet 11.

[0145] Based on the real-time calculated state-space model, the controller instructs the proportional pressure regulating valve in the air path of the spray gun 10 to output dynamically changing forming air pressure, and uses the airflow reaction force to apply non-contact damping to the workpiece, locking the random swing in a controllable phase.

[0146] On the other hand, the controller instructs the industrial robot 9 to execute a variable-speed scanning trajectory that matches the changes in air pressure and temperature distribution. It uses a speed compensation mechanism to offset the film thickness deviation caused by the deformation of the fan surface, and simultaneously adjusts the electrostatic voltage to adapt to the leveling characteristics of different areas.

[0147] This equipment effectively solves the problem of spraying distance fluctuation caused by workpiece swaying during suspended conveying without the need for additional mechanical fixing fixtures. At the same time, it overcomes the coating quality differences caused by uneven heat dissipation in complex die-cast parts, ensuring that the cured finished product has a uniform appearance.

Claims

1. A steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional sensing, characterized in that, Includes the following steps: S1. Using a laser profile sensor (7) and an infrared thermal imager (8), the distance point cloud and thermal radiation signal of the aluminum die-cast workpiece are collected, the motion vector is calculated, and the local temperature is generated by mapping. S2. Based on the motion vector, construct an oscillation model to obtain phase prediction; based on the local temperature, construct a rheological model; perform temperature threshold determination and generate rheological parameters. S3. Based on the motion vector and the phase prediction, the swing direction is determined to generate a direction determination. Combined with the preset position stiffness, pneumatic damping and reference air pressure, the air pressure command is calculated using the pneumatic vibration suppression formula to generate a pneumatic repulsive force when the workpiece approaches the spray gun (10). S4. Determine the deformation index based on the air pressure command and the temperature factor based on the local temperature, and calculate the real-time scanning speed command using the thermal-speed coupling formula to offset the fan-shaped deformation and correct the leveling difference. S5. The proportional pressure regulating valve of the spray gun (10) is driven by the air pressure command to achieve phase locking, the industrial robot (9) is driven by the speed command to perform speed compensation, and the electrostatic voltage of the spray gun (10) is adjusted according to the rheological parameters. Specifically, step S1 includes: The distance point cloud relative to the suspension vertical line is obtained by continuously scanning the aluminum die-casting workpiece moving with the suspended conveyor chain (6) using a laser profile sensor (7) installed on the entry side of the spraying chamber (5). The distance point cloud is subjected to temporal differentiation to calculate the swing angle and swing angular velocity at the current timestamp, and combined to form the motion vector. The thermal radiation signal of the workpiece surface is collected simultaneously using an infrared thermal imager (8) installed on the entry side of the spraying chamber (5); The thermal radiation signal is mapped onto the digital model mesh of the workpiece to generate the discretized local temperature.

2. The steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional perception according to claim 1, characterized in that, In step S2, constructing the oscillation model to obtain the phase prediction specifically includes: By introducing the motion vector and substituting it into the Lagrange dynamics equation, a swing model of the workpiece in the suspended state is constructed. Based on the swing model, the time is extrapolated backward to calculate the phase prediction when the workpiece reaches the working position.

3. The steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional perception according to claim 1, characterized in that, In step S2, constructing a rheological model based on the local temperature, performing temperature threshold determination, and generating rheological parameters specifically includes: By introducing the local temperature and combining the specific heat capacity of aluminum alloy with the viscosity and temperature curves of powder coating, the rheological model is constructed, and the relationship between temperature and leveling is established. According to the rheological model, the region where the local temperature is higher than the set leveling threshold is a high leveling region, the region where the local temperature is lower than the set wetting threshold is a low wetting region, and the region where the local temperature is neither higher than the set leveling threshold nor lower than the set wetting threshold is a standard working area. The rheological parameters are generated by matching the corresponding baseline process parameters for the high leveling zone, the standard operating zone, and the low wetting zone, respectively. The set leveling threshold is preset based on the melt viscosity characteristics of the powder coating, the set wetting threshold is preset based on the glass transition temperature of the powder coating, the specific heat capacity of the aluminum alloy is obtained based on a pre-stored material property database, and the viscosity-temperature curve of the powder coating is obtained by differential scanning calorimetry or rotational rheometer testing.

4. The steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional perception according to claim 1, characterized in that, In step S3, the direction determination based on the motion vector and the phase prediction specifically includes: Extract the oscillation angular velocity from the motion vector; The angular velocity of the swing is calculated using a sign function to determine whether the workpiece is moving away from or towards the spray gun (10), thereby determining the swing direction; The direction of the swing is combined with the phase prediction to generate the direction determination.

5. The steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional perception according to claim 1, characterized in that, In step S3, calculating the air pressure command using the pneumatic vibration suppression formula specifically includes: Introduce the swing angle and the swing angular velocity into the motion vector; The air pressure command is generated by combining the preset position stiffness, aerodynamic damping and reference air pressure, using the aerodynamic vibration suppression formula; The air pressure command is used to drive the proportional pressure regulating valve to output a pressure higher than the reference air pressure when the direction determination indicates that the workpiece is close to the spray gun (10); The position stiffness and the pneumatic damping are preset based on the mass and suspension length of the workpiece, and the reference air pressure is preset based on the standard atomizing fan width requirement of the spray gun (10).

6. The steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional perception according to claim 3, characterized in that, In step S4, determining the deformation index based on the air pressure command and determining the temperature factor based on the local temperature specifically includes: By introducing the air pressure command, the deformation index is calculated based on the nonlinear relationship between pressure and fan width; Introducing the local temperature, the temperature factor is calculated based on the temperature-leveling relationship defined in the rheological model.

7. The steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional perception according to claim 1, characterized in that, In step S4, the calculation of the speed command using the thermal-rate coupling formula specifically includes: The air pressure command, the deformation index, and the temperature factor are introduced. The speed command is generated by combining the preset reference speed and the reference air pressure using the thermal-speed coupling formula. The speed command is used to instruct the industrial robot (9) to increase the scanning speed when the increased air pressure command causes the fan to contract; The reference speed is preset based on production cycle requirements and standard film thickness.

8. The steady-state compensation control method for aluminum die-casting spraying based on multi-dimensional perception according to claim 3, characterized in that, In step S5, adjusting the electrostatic voltage of the spray gun (10) according to the rheological parameters specifically includes: The air pressure command is applied to the proportional pressure regulating valve in the air circuit of the spray gun (10) to output pulsed pneumatic thrust and achieve phase locking; The speed command is applied to the industrial robot (9) to drive the spray gun (10) to scan the workpiece with a variable speed trajectory, thereby achieving the speed compensation; According to the local temperature and the rheological parameters, the electrostatic voltage of the spray gun (10) is adjusted synchronously, the voltage is reduced in the high leveling zone, the voltage is increased in the low wetting zone, and the reference voltage is maintained in the standard working zone to achieve electrostatic adsorption.

9. An aluminum die-casting spray coating production line, characterized in that, The method for steady-state compensation control of aluminum die casting spraying based on multi-dimensional perception, as described in any one of claims 1-8, includes a melting furnace (1), a die casting machine (2), a conveyor belt (3), a spraying chamber (5), an industrial robot (9), and an electrical control cabinet (11). The melting furnace (1) is located on the feeding side of the die casting machine (2), the conveyor belt (3) is located in the discharging direction of the die casting machine (2), a cooling fan (4) is installed on the top of the conveyor belt (3), and the spraying chamber (5) is located in the discharging direction of the conveyor belt (3). A suspended conveyor chain (6) is provided on the top of the coating bin (5). A laser profile sensor (7) and an infrared thermal imager (8) are installed on the entry side of the coating bin (5). An industrial robot (9) is located on the side of the coating bin (5). A spray gun (10) is installed on the end flange of the industrial robot (9). The electrical control cabinet (11) is connected to the laser profile sensor (7), the infrared thermal imager (8), the servo driver of the industrial robot (9), and the proportional pressure regulating valve in the air circuit of the spray gun (10).

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