Hanging spraying method, storage medium, electronic equipment and device

Abstract

The invention relates to the technical field of spraying, in particular to a hanging spraying method, a storage medium, electronic equipment and device.According to the hanging spraying method, firstly, magnetic nanoparticles are added into paint, so that the atomized paint can be driven by a magnetic field; then, B particles with large particle sizes are driven to the lower portion of the layering area through cooperation of a magnetic field and the air pressure difference, A particles with small particle sizes are driven to the upper portion of the layering area, an A particle layer and a B particle layer are obtained, and then the workpiece is driven to sequentially pass through the area covered by the B particle layer and the area covered by the B particle layer in the adsorption area in the second direction, the particles B are firstly adsorbed to the workpiece under the action of the electric field, and then the particles A are adsorbed to the workpiece under the action of the electric field, so that the particles with larger particle sizes are firstly adsorbed, local accumulation caused by gravity or airflow disturbance after the particles are mixed with the particles with smaller particle sizes is avoided, the defect that the surface of a coating is uneven is reduced, and the coating quality is improved. And the spraying uniformity is improved.

Description

Technical Field

[0001] The present invention relates to the field of spraying technology, and in particular to a hanging spraying method, a storage medium, an electronic device and a device. Background Art

[0002] In the traditional electrostatic spraying process, the uniformity of the paint film is seriously restricted by the uneven distribution of the particle size of the atomized particles. The centrifugal force generated by the high-speed rotation (30,000-50,000RPM) of the rotary cup atomizer breaks the paint into mixed particle groups (typical particle size range 10-80μm). However, due to the fluctuation of the paint viscosity (±20cP), the unstable air shear force (pressure fluctuation>0.05MPa) and the atomization edge effect, large particles (50-80μm) and small particles (10-20μm) will be formed in the particle group at the same time. Large particles have a large mass (mass is proportional to the cube of the radius, m∝r 3 ) causes the inertial sedimentation velocity to be too fast (Stokes sedimentation velocity vs = 2r 2 (ρ p -ρ f )g / (9η), ρp is the particle density, η is the air viscosity), and small particles are easily disturbed by air turbulence (turbulence is significant when the Reynolds number Re>2000) to form suspended aerosols.

[0003] Effect of particle size on spraying quality

[0004] 1. Uneven coating thickness: Large particles settle prematurely (sedimentation time t1 < 0.2s), resulting in local accumulation (standard deviation of film thickness reaches ± 3μm), while small particles are difficult to be effectively adsorbed due to their long suspension time (t2 > 0.4s), resulting in incomplete surface coverage (porosity > 5%).

[0005] 2. Surface morphology defects: When large particles hit the substrate, the kinetic energy is high (kinetic energy E k =0.5mv 2 The kinetic energy of particles with a diameter of 60 μm is 27 times that of particles with a diameter of 20 μm), which can easily cause splashing or "crater" effects (surface roughness Ra increases to 1.2-1.5 μm); small particles are significantly affected by Brownian motion (diffusion coefficient D = k B T / (6πηr), when r=10μm, D≈1.2×10-11m 2 / s) causes paint mist to float (coating utilization rate <65%).

[0006] 3. Deterioration of optical properties: For coatings containing effect pigments (such as aluminum powder or pearlescent powder), large particles (>50μm) cause color difference (ΔE>1.5) due to the discrete mirror reflection angle, while small particles (<20μm) cause gloss reduction due to multiple scattering (60° gloss value drops from 90GU to 75GU).

[0007] In the existing technology, although the atomization uniformity can be partially improved by adjusting the rotating cup speed, electric field strength (60-80kV / m) or air pressure (0.3-0.5MPa), it cannot fundamentally solve the problem of dynamic separation of mixed particles. For example, simply increasing the electric field strength can enhance the adsorption of small particles, but it will aggravate the electrostatic repulsion of large particles (Coulomb force F e =qE is proportional to the particle surface area, with larger particles having a higher charge q. However, graded atomization technologies (such as dual-cup systems) are difficult to promote in industrial settings due to equipment complexity and cost constraints (increasing energy consumption by 30%-50%). Therefore, a new spraying technology that can actively control the motion trajectory of mixed particles and achieve stratified deposition by particle size is urgently needed. Summary of the Invention

[0008] The present invention provides a hanging spraying method, a storage medium, an electronic device and a device, which are used to solve the technical problem in the prior art of uneven coating thickness caused by particle size differences in electrostatic spraying.

[0009] A first aspect of the present invention provides a hanging spraying method, comprising:

[0010] S1: adding magnetic nanoparticles to the coating to obtain a mixed coating;

[0011] S2: atomizing the mixed coating in the atomization zone of the spraying room through a single rotary cup to obtain mixed particles;

[0012] S3: driving the mixed particles to move in a first direction into a stratification zone of a spraying chamber;

[0013] S4: dividing the mixed particles into an A particle layer and a B particle layer in a stratified region by a magnetic field and an air pressure difference, wherein the particle size range of the A particles in the A particle layer at the upper portion of the stratified region is (a, A), and the particle size range of the B particles in the B particle layer at the lower portion of the stratified region is (b, B), wherein A<B, and the overlapping range of (a, A) and (b, B) is less than or equal to 15% of (a, B);

[0014] S5: driving the A particle layer and the B particle layer to move in a first direction into an adsorption area of the spraying chamber;

[0015] S6: Control the workpiece to move along a second direction through the adsorption area, where the second direction forms an obtuse angle with the first direction.

[0016] In a first possible hanging spraying method of the first aspect, dividing the mixed particles into particle layer A and particle layer B by a magnetic field and air pressure difference in the stratified area includes:

[0017] The gradient magnetic field is used to force the B particles to sink, and the upward airflow is used to lift the A particles into suspension. The gradient magnetic field is from top to bottom and the magnetic field direction is vertically downward. The airflow is generated by the air intake system located at the bottom of the stratification area and the air exhaust system located at the top of the stratification area.

[0018] In combination with the first possible hanging spraying method of the first aspect, in the second possible hanging spraying method of the first aspect, the gradient magnetic field constrains the magnetic flux divergence angle ≤3° and the magnetic field linearity error ≤2% through the wedge-shaped magnetic conductive plate.

[0019] In a third possible hanging spraying method of the first aspect, S6 includes:

[0020] S61: offsetting the gravitational settling of particles A and B by using an anti-gravity air curtain and ultrasonic standing waves;

[0021] S62: Control the workpiece to move along a second direction through the adsorption area, where the second direction forms an obtuse angle with the first direction.

[0022] In the fourth possible hanging spraying method of the first aspect, the motion trajectory formula of the workpiece in the adsorption area is: x (t) = k·v z +W·sin(2πft+φ);

[0023] Where: v x is the instantaneous moving speed of the workpiece in the X direction, which is opposite to the first direction, v z is the main motion velocity in the Z direction, which is perpendicular to the X direction, k is the linear coupling coefficient between the X-direction velocity and the Z-direction velocity, which is dimensionless, k = tanθ, θ is the angle between the second direction and the X direction, W is the amplitude of the periodic disturbance, f is the disturbance frequency, φ is the initial phase angle, and t is the time variable.

[0024] In a fifth possible hanging spraying method of the first aspect, after S6, the method further includes:

[0025] S7: A negative pressure recovery device is set on the side of the adsorption zone away from the stratification zone to recover the unattached A particles and B particles.

[0026] In a sixth possible hanging spraying method of the first aspect, S4 further includes:

[0027] S41: Detecting the particle size distribution of the mixed particles by a laser particle size analyzer;

[0028] S42: adjusting the intensity of the gradient magnetic field and the speed of the upward airflow according to the particle size distribution.

[0029] The second aspect of the present invention provides an electronic device, comprising a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement any possible steps of the hanging spraying method provided in the first aspect.

[0030] A third aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any possible hanging spraying method provided in the first aspect.

[0031] A fourth aspect of the present invention provides a steel scraper defect detection device, comprising:

[0032] spray booths and rigging assemblies;

[0033] The spray chamber includes an atomization zone, a stratification zone, and an adsorption zone sequentially distributed along a first direction;

[0034] The atomization area is equipped with a single rotary cup;

[0035] The stratified area is equipped with a magnetization component, an air intake system, and an air extraction system;

[0036] The adsorption area is provided with an electric field component;

[0037] The hanging assembly is used to drive the workpiece to pass through the adsorption area along the second direction.

[0038] It can be seen from the above technical solutions that the present invention has the following advantages:

[0039] ① This technical solution adds magnetic nanoparticles to the coating so that the atomized coating can be driven by the magnetic field, and then the larger B particles are driven to the lower part of the stratification zone and the smaller A particles are driven to the upper part of the stratification zone through the combination of the magnetic field and the air pressure difference, thereby realizing the stratification of large and small particles, obtaining A particle layer and B particle layer, and then driving the workpiece along the second direction through the area covered by the B particle layer and the area covered by the B particle layer in the adsorption zone in sequence, so that the larger B particles are first adsorbed onto the workpiece under the action of the electric field, and then the smaller A particles are adsorbed onto the workpiece under the action of the electric field. By first adsorbing the larger particles, local accumulation caused by gravity or airflow disturbance after mixing with the smaller particles is avoided, thereby reducing the uneven defects on the coating surface and improving the uniformity of the spraying.

[0040] ② The preferential adsorption of larger particles can reduce their circulation loss in the recovery system, while the extended suspension time of small particles improves the adsorption efficiency. In addition, step-by-step adsorption allows independent optimization of parameters to avoid uneven coating caused by parameter conflicts.

[0041] ③Through step-by-step adsorption, particles with larger particle sizes are first stably deposited on the bottom layer, and particles with smaller particle sizes are then driven by the electric field to fill the gaps, forming a continuous coating and effectively reducing the standard deviation of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A schematic flow chart of a hanging spraying method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] Embodiments of the present invention provide a hanging spraying method, storage medium, electronic equipment, and device, which are used to solve the technical problem of uneven coating thickness caused by particle size differences in electrostatic spraying in the prior art.

[0045] In order to make the purposes, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0046] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0047] In the description of the embodiments of the present application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, replaceable connections, or integral connections. They can also refer to mechanical connections or electrical connections. They can also refer to direct connections or indirect connections through an intermediate medium. They can also refer to internal connections between two components. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0048] In the existing technology, although the atomization uniformity can be partially improved by adjusting the rotating cup speed, electric field strength (60-80kV / m) or air pressure (0.3-0.5MPa), it cannot fundamentally solve the problem of dynamic separation of mixed particles. For example, simply increasing the electric field strength can enhance the adsorption of small particles, but it will aggravate the electrostatic repulsion of large particles (Coulomb force F e =qE is proportional to the particle surface area, with larger particles having a higher charge q). However, graded atomization technologies (such as the double-cup system) are difficult to promote in industrial scenarios due to equipment complexity and cost limitations (increasing energy consumption by 30%-50%).

[0049] Example 1

[0050] See also Figure 1 The hanging spraying method provided by the embodiment of the present invention includes:

[0051] S1: adding magnetic nanoparticles to the coating to obtain a mixed coating;

[0052] Specifically, this step is to achieve magnetic modification of the coating. The introduction of magnetic particles gives the coating magnetic response characteristics, so that the movement of particles can be controlled by a gradient magnetic field to achieve the stratification of particles of different particle sizes. For example, ferroferric oxide magnetic nanoparticles with a particle size of 30-50nm are added to the polyurethane coating and mixed at 2000rpm for 15 minutes using a twin-screw high-speed disperser to form a mixed coating.

[0053] S2: In the atomization area of the spraying room, the mixed coating is atomized by a single rotary cup to obtain mixed particles;

[0054] Specifically, in this step, a single rotary cup (electrostatic rotary cup atomizer) is used to break the mixed paint into mixed particles of the required particle size range under the high voltage electric field and the drop in atomizing air pressure. In addition, the mixed paint needs to be preheated before atomization to reach a certain viscosity before atomization. For example, the paint tank was preheated to 40±2°C 30 minutes before start-up, and the paint viscosity was confirmed to be within the range of 180-220 mPa·s using an online viscometer (Brookfield DV3T). When the viscosity reached the target, the rotary cup motor was started and the speed was controlled according to the following logic: Initial stage: linearly increase from 0 to 30,000 rpm within 10 seconds (anti-splash start); Stabilization stage: maintain 50,000±500 rpm. If the paint flow fluctuation was detected to be greater than 5%, the speed was dynamically adjusted according to Δrpm = 100×(actual flow - set flow); After the single rotary cup reached the target speed, the electrostatic generator was turned on and increased to -90 kV at a rate of 10 kV / s. The charge-to-mass ratio was monitored in real time using an electrostatic probe. If it deviated from 1.2×10 -4 If C / kg exceeds ±10%, an alarm is triggered and feeding is suspended, thereby atomizing the mixed coating to obtain mixed particles.

[0055] S3: driving the mixed particles to move in a first direction into a stratification zone of the spray chamber;

[0056] Specifically, the purpose of this step is to drive the mixed particles to migrate in a directional manner from the atomization zone into the stratification zone, and to set a horizontal magnetic field or electric field in the atomization zone to drive the mixed particles to move in the first direction and enter the stratification zone. For example, by setting parallel electrode plates in the atomization zone to generate a field strength, a horizontal DC electric field in the first direction is formed to drive the mixed particles into the stratification zone.

[0057] S4: dividing the mixed particles into a particle layer A and a particle layer B in the stratified region by a magnetic field and a pressure difference, wherein the particle size range of the A particles in the particle layer A at the upper portion of the stratified region is (a, A), and the particle size range of the B particles in the particle layer B at the lower portion of the stratified region is (b, B), wherein A < B, and the overlapping range of (a, A) and (b, B) is less than or equal to 15% of (a, B);

[0058] Specifically, the different particle sizes determine how the particles respond to magnetic fields and pressure differences. Therefore, different magnetic forces and pressures can be applied to particles of different sizes through the magnetic field and pressure difference, causing the larger B particles to move to the lower part of the stratification zone to form the B particle layer, and the smaller A particles to move to the upper part of the stratification zone to form the A particle layer, thereby achieving upper and lower stratification of particles of different sizes. Because the control accuracy of the magnetic field and pressure difference cannot achieve complete stratification, there is an overlap in the particle size ranges of the A particle layer and the B particle layer. For example, if the particle size range of the mixed particles is (10, 80), the particle size range of the A particle layer is (10, 40), and the particle size range of the B particle layer is (29.5, 80). That is, the particle size overlap range of the A particle layer and the B particle layer is (29.5, 40). It is necessary to ensure that this overlap range is less than or equal to 15% of the particle size range (10, 80), that is, the difference between the maximum and minimum values of the overlap range is less than or equal to 10.5. In theory, the smaller the overlap range, the better. The particle size range of particle layer A and particle layer B is determined by the control accuracy that can be achieved by the magnetic field and air pressure difference and the required spraying quality.

[0059] Optimized, in order to solve the problem of mixing particles of different particle sizes, this step realizes particle size stratification through the synergistic effect of the gradient magnetic field and the airflow, utilizing the physical mechanism that large particles (B particles) are dominated by magnetic force to sink, and small particles (A particles) are suspended by aerodynamic force. The gradient magnetic field forces the B particles to sink, and the upward airflow lifts the A particles to suspend. The gradient magnetic field is from top to bottom and the magnetic field direction is vertically downward. The airflow is generated by the air intake system located at the bottom of the stratification area and the air exhaust system located at the top of the stratification area. More specifically, a permanent magnet array is arranged at the top of the stratification area, and an electromagnetic coil is installed at the bottom to form a gradient field with decreasing magnetic field strength from top to bottom. The N pole of the permanent magnet array faces downward and is superimposed in the same direction as the magnetic field generated by the electromagnetic coil to ensure that the magnetic field direction is strictly vertically downward (magnetic line deflection angle <2°, verified by a Gauss meter). The magnetic field strength is monitored in real time by the Hall sensor. When it is detected that the field strength at a certain point deviates from the set gradient curve by more than ±5%, the PLC controller automatically adjusts the electromagnetic coil current (ΔI = 0.1A / 0.01T deviation). According to the magnetic formula: Where χ is the magnetic susceptibility of the particle, V is the particle volume, represents the spatial gradient of magnetic field energy density, B 2 / (2μ0) is the energy stored in the magnetic field per unit volume (unit: J / m 3 ), where B is the magnetic induction intensity, μ0=4π×10 -7H / m is the magnetic permeability of vacuum. It can be seen that particles B (larger in size) experience a magnetic force F_m 3-5 times greater than particles A due to their significantly greater V value, leading to their preferential downward migration. Intake system: A porous gas distribution plate is installed at the bottom of the stratification zone, connected to a centrifugal fan. A PID controller stabilizes the intake velocity within a certain range. Exhaust system: An annular exhaust hood is installed at the top of the stratification zone, equipped with a variable-frequency induced draft fan. This creates an upward net airflow with the bottom intake, achieving an airflow ratio (extraction / intake) of 1.05:1 to maintain a slight negative pressure. The bottom intake system (centrifugal fan + porous plate) and the top exhaust system (induced draft fan + exhaust hood) form a closed-loop air circuit, creating a "bottom-intake, top-exhaust" structure. According to the aerodynamic balance equation: F_a = 3πμd_p(v_g - v_p) (Stokes' law), where μ is the air viscosity and d_p is the particle diameter. Particle A (small d_p) has a terminal velocity v_p lower than the airflow velocity v_g, thus remaining suspended. Particle B (large d_p) sinks because v_p > v_g. Furthermore, to reduce particle adhesion, a polytetrafluoroethylene coating is applied to the inner wall of the stratification zone. To enable online monitoring, a quartz glass observation window is installed in the middle of the stratification zone for online laser particle size monitoring.

[0060] To further optimize the system and address the blurred stratification boundaries caused by diverging magnetic flux lines, the parameter ranges for airflow velocity, magnetic field intensity, and magnetic field linearity were further restricted based on the previous optimization. Specifically, a frequency converter (accuracy ±0.01Hz) was installed at the front end of the centrifugal blower, and a Pitot tube (accuracy class 0.5) was used to monitor the airflow velocity in the middle of the stratified zone in real time. If the speed deviated beyond a certain setpoint, the frequency converter automatically adjusted the motor speed. Furthermore, to suppress turbulence, a honeycomb rectifier was installed between the air inlet distribution plate and the exhaust hood to reduce the turbulence intensity, thereby stabilizing the speed at the target and ensuring that the A particle suspension height fluctuation was less than ±5mm. The top permanent magnet array employed a Halbach structure (NdFeB N52). A wedge-shaped magnetic plate (pure iron DT4C, wedge angle 15°) was used to reduce the magnetic flux divergence angle from 8° (conventional) to 2.5°. The bottom electromagnetic coil employed a double-layer winding, fed with direct current to generate an adjustable auxiliary magnetic field. Gradient linearization control: Fluxgate sensors (accuracy ±0.5%) are evenly spaced along the height of the delamination zone, providing real-time magnetic field strength feedback to the PLC. When the magnetic field gradient deviates from the target range in a particular segment, the current in the corresponding electromagnetic coil is adjusted to maintain the overall magnetic field linearity error ≤1.8%. Magnetic field calibration process: A three-dimensional gaussmeter (Lakeshore 475) is used to scan the magnetic field along the axis of the delamination zone with no load to generate a B(z) curve. The maximum deviation ΔB_max of the measured curve is compared with the ideal linear curve. If ΔB_max / B_avg is greater than 2%, the spacing between the wedge-shaped magnetic plates is adjusted (adjustment amount Δd = 1mm / 1% deviation).

[0061] In order to ensure the stability of the adsorption efficiency of particles A and B, the following steps are added to step S4:

[0062] S41: Detecting the particle size distribution of the mixed particles by a laser particle size analyzer;

[0063] Specifically, an online laser particle size analyzer is installed in the stratified area, with its optical window at a 45° angle to the airflow direction. The particle size analyzer uses Mie scattering theory to invert the particle size distribution and outputs Dv10, Dv50, Dv90, and Span values (Span = (Dv90-Dv10) / Dv50) in real time. The data is transmitted to the PLC controller via Modbus TCP. Among them, Dv10 (10% cumulative particle size): 10% of the particles in the particle group have a particle size less than or equal to this value (weighted by volume), representing the distribution boundary of the fine particle end and reflecting the proportion of the "minimum particle size segment" in the mixed particles. If Dv10 decreases significantly (for example, from 1.2μm to 0.8μm), it means that the proportion of fine particles has increased, and the airflow velocity needs to be increased to suspend the smaller A particles. Dv50 (median particle size / 50% cumulative particle size): 50% of the particles in the particle group have a particle size less than or equal to this value, and 50% are greater than this value. This reflects the average particle size of the particle group and is the core indicator of distribution. When the Dv50 of B particles increases (such as from 2.5μm to 3.0μm), the magnetic field strength needs to be increased to provide sufficient magnetic adsorption force. When the Dv50 of A particles decreases, the air flow velocity needs to be increased to overcome the van der Waals force. Dv90 (90% cumulative particle size): 90% of the particles in the particle group have a particle size less than or equal to this value. This characterizes the distribution boundary of the coarse particle end and reflects the proportion of the "maximum particle size segment". If Dv90 increases abnormally (such as from 5μm to 7μm), it indicates that large particles are agglomerated and an anti-caking agent needs to be added. Span value (distribution width index): The larger the Span value, the wider the particle size distribution (the larger the difference in particle size); the smaller the Span value, the more concentrated the distribution. Span>2.5: The distribution is too wide, resulting in the failure of the synergy between magnetic adsorption and air suspension, and particle size classification screening (such as airflow screening or centrifugal separation) needs to be started; Span<1.0: The distribution is too narrow, which may reduce the density of the coating structure, and the particle mixing ratio needs to be adjusted.

[0064] S42: Adjusting the intensity of the gradient magnetic field and the speed of the upward airflow according to the particle size distribution.

[0065] Specifically, the electromagnetic array current is dynamically adjusted based on the Dv50 of the B particles, and the centrifugal fan frequency is dynamically adjusted based on the Dv50 of the A particles. For example, when Dv50_B (the median particle size of the B particles) increases from 2.0μm to 3.0μm, the magnetic field strength needs to be increased to maintain a match between the magnetic attraction force and the particle size. If Dv50_A (the median particle size of the A particles) decreases from 1.0μm to 0.7μm, the airflow velocity needs to be increased to ensure effective suspension of small particles.

[0066] The laser particle size analyzer (S41) and the field intensity / airflow adjustment (S42) form a closed-loop control, directly realizing "adjusting the gradient magnetic field and airflow velocity according to the particle size distribution".

[0067] S5: driving the A particle layer and the B particle layer to move in a first direction into an adsorption area of the spraying chamber;

[0068] Specifically, the purpose of this step is to transport the A and B particle layers from the separation zone to the adsorption zone. After obtaining the A and B particle layers, the A and B particle layers are driven by electric or magnetic forces to move in a first direction while preventing them from mixing, thereby allowing them to enter the adsorption zone of the spray chamber. The movement of the A and B particle layers can be controlled uniformly or independently. Independent control can adjust the transport speed of the A and B particles according to different adsorption conditions.

[0069] S6: Control the workpiece to move along a second direction through the adsorption area, where the second direction forms an obtuse angle with the first direction.

[0070] Specifically, after the A particle layer enters the upper portion of the adsorption zone and the B particle layer enters the lower portion of the adsorption zone, the workpiece is controlled to pass through the adsorption zone along a first direction, and a second direction forms an obtuse angle with the first direction, i.e., the workpiece sequentially passes through the lower and upper portions of the adsorption zone. Thus, when the workpiece is located in the lower portion of the adsorption zone, the B particles in the B particle layer are first adsorbed onto the workpiece under the action of the electric field force. After a uniform layer of B particles is adsorbed on all surfaces of the workpiece, the workpiece enters the upper portion of the adsorption zone, and the A particles are adsorbed onto the workpiece under the action of the electric field force, i.e., covering the B particle layer, thereby achieving the first adsorption of larger particles and the last adsorption of smaller particles. For example, if the first direction is the left-right direction, and the spray chamber is sequentially divided from left to right into the atomization zone, the stratification zone, and the adsorption zone, then the workpiece moves from the lower right to the upper left within the adsorption zone, i.e., the movement path forms an obtuse angle with the first direction, preferably 120°-150°. The movement speed of the workpiece in the lower portion of the adsorption zone is less than the movement speed in the upper portion of the adsorption zone.

[0071] Optimized, after entering the adsorption zone, the particles may settle under the action of gravity, thereby causing the mixing of particle layer A and particle layer B. In order to avoid this situation, the particles are made to achieve a zero-gravity suspension state in the adsorption zone through inverse gravity compensation. Specifically, the gravity sedimentation of particles A and B is offset by the inverse gravity air curtain and ultrasonic standing wave, and then the workpiece is controlled to move through the adsorption zone in the second direction, and the second direction forms an obtuse angle with the first direction. Construction of inverse gravity air curtain - an annular slit nozzle is arranged at the bottom of the adsorption zone, and compressed air is introduced to form an upward conical air curtain. The air curtain velocity gradient satisfies: V(z) = V0·e -kzAmong them, V0 is the nozzle outlet velocity, k is the attenuation coefficient, which is 0.02 / mm, and z is the height of the workpiece. Generation of ultrasonic standing wave field - a piezoelectric transducer array is installed on the top of the adsorption area, and a reflector is installed on the bottom. The sound wave is formed into a standing wave through a phase controller to achieve the required sound pressure level. The net gravity of the particles is reduced by the synergistic effect of the dual fields. At the same time, the cross-scale coupling of the air curtain (macroscopic force field) and ultrasound (microscopic force field) solves the problem that a single force field is difficult to take into account both large flow and high precision. The workpiece fixture is then connected to the robotic arm (repeat positioning accuracy ±0.02mm) and moves along the inclined guide rail (angle θ = 135°) at a speed of 0.5-1.2m / s. The second direction (adsorption movement direction) forms an obtuse angle of θ=135°±2° with the first direction (particle injection direction). The oblique movement prolongs the adsorption time compared to the orthogonal path. The Coanda effect generated by the obtuse movement causes the particles to form laminar adhesion on the surface of the workpiece, reducing the Reynolds number. The obtuse movement path breaks through the traditional vertical spraying mindset and achieves double gains by extending the effective action time and improving the flow field distribution. The robot arm motion controller is linked to the paint injection valve. When the workpiece displacement Δs>0.1mm is detected, the injection valve flow compensation is triggered. The injection valve is a fluid control device, usually a solenoid valve or a piezoelectric valve, which is used to accurately control the start and stop timing, pulse frequency and flow of the paint. During spraying, the valve is responsible for responding to electrical signals, instantaneously opening / closing the paint channel, and realizing dynamic adjustment of the spraying parameters. The feeding system of a single rotary cup (such as a gear pump) has a hysteresis when adjusting the flow, while the injection valve can achieve microsecond switching through a piezoelectric crystal, accurately matching the phase disturbance.

[0072] Further optimization is achieved by designing a composite motion trajectory and superimposing high-frequency micro-perturbations on the basis of obtuse angle motion, so that the particles form a self-organized arrangement on the surface of the workpiece and reduce the standard deviation of the coating thickness. Specifically, the motion trajectory formula of the workpiece in the adsorption area is: v x (t) = k·v z +W·sin(2πft+φ); where: v x is the instantaneous moving speed of the workpiece in the X direction, which is opposite to the first direction, v zis the main motion speed in the Z direction, the Z direction is perpendicular to the X direction, k is the linear coupling coefficient of the X direction speed and the Z direction speed, is dimensionless, k = tanθ, θ is the angle between the second direction and the X direction, W is the amplitude of the periodic disturbance, f is the disturbance frequency, φ is the initial phase angle, and t is the time variable. For example, a linkage robot arm (repeat positioning accuracy ± 0.005mm) is used, the X-axis guide rail is antiparallel to the particle injection direction (first direction), and the Z-axis guide rail is orthogonal to the X-axis. A six-dimensional force sensor (range ± 500N, resolution 0.01N) is installed at the end of the robot arm to feedback the force data in real time. Trajectory parameter setting: linear coupling coefficient: k = tan (135°) = -1 (corresponding to the angle θ between the second direction and the X-axis = 135°), disturbance parameter group: W = 15mm (amplitude), f = 50Hz (disturbance frequency), φ = π / 3 (initial phase angle), main motion speed: v z =0.8m / s (uniform motion in the Z direction), the actual motion trajectory of the workpiece is realized by vector synthesis in the XZ plane, and the instantaneous speed satisfies: vx(t)=-vz+15·sin(100πt+π / 3), the opening period of the injection valve is locked with the disturbance phase, when sin(100πt+π / 3)>0.9, the controller sends a pulse signal to the injection valve, and the injection valve opens quickly within 2ms. The high-pressure paint (such as 30MPa) is transported to the single rotary cup through the pipeline, and the single rotary cup receives the paint and rotates at high speed to atomize. A μ-level coating thickness gauge is arranged at the outlet of the adsorption zone to generate a thickness distribution thermogram in real time. Dynamic adjustment parameters based on thickness data:

[0073] k new =k old +0.05·Δh / h avg

[0074] W new =W old ·[1+0.2·sin(2πf adj t)]

[0075] Among them, k new is the new linear coupling coefficient k, k old is the old linear coupling coefficient k, W new is the amplitude of the new periodic disturbance, W old is the amplitude of the old periodic disturbance, Δh is the local thickness deviation, and f adj To adjust the frequency, Δh / h avg Indicates the normalized value of thickness deviation, multiplied by a coefficient of 0.05 to avoid oscillation caused by excessive adjustment.

[0076] When Δh > 0 (locally overthick), particle deposition in this area needs to be reduced. Therefore, the k value is increased (i.e., the X-direction velocity component is increased) to enable faster lateral movement of the workpiece and shorten the particle dwell time in the overthick area. When Δh < 0 (locally thin), deposition needs to be increased. Therefore, the k value is decreased (i.e., the lateral velocity is slowed) to prolong the particle adsorption time in the thin area. By varying the k value, the overall velocity component of the workpiece's motion in the X direction is controlled, thereby adjusting the lateral coverage of the particle surface and compensating for systematic thickness deviations caused by spray distance and uneven flow fields. The W value determines the amplitude of the periodic perturbation and directly influences the diffusion capacity of particles at the microscale: Increasing W enhances perturbation, promoting particle penetration into recessed areas and improving edge coverage. Decreasing W weakens perturbation, suppressing particle splashing, and improving uniformity across planar surfaces. By dynamically varying the W value, the amplitude of the perturbation in the X direction of the workpiece is controlled, thereby optimizing particle distribution uniformity and edge penetration, adapting to varying geometric features of the workpiece surface (such as corners and holes). The thickness gauge monitors the coating thickness in real time and generates Δh data. The controller calculates the new values of k and W based on Δh and updates the motion trajectory equation:

[0077] v x (t) = k new ·v z +W new ·sin(2πft+φ).

[0078] Stability guaranteed: through energy function V = 0.5e 2 +0.5e ·2 , to ensure the convergence of the parameter adjustment process and avoid system oscillation, where e (thickness deviation) is the difference between the actual thickness of the sprayed coating and the target thickness (e = hactual - htarget). · (Deviation change rate): The rate at which the thickness deviation changes over time (e · = de / dt), the thickness deviation (e) and its rate of change (e˙) are weighted and combined to form a virtual energy index, which is used to quantify the "instability" of the system: the larger the V value, the further the system deviates from the target state, and the deviation is still expanding (instability); the smaller the V value, the system is close to or stabilized at the target state (stable). In the adaptive control algorithm, by adjusting the parameters k and W, the energy function satisfies: dV / dt < 0 (energy continuously decays over time). The time derivative of V is calculated as:

[0079] dV / dt=ee · +e · e ··

[0080] By adjusting the control parameters (such as adjusting k and W), when e increases, the control effect makes e · Reverse direction (e.g. increasing k to reduce deposition); when e· When it is too fast, the control action suppresses the acceleration e ·· Finally, dV / dt<0 is ensured, and the system energy continues to decay to a balanced state.

[0081] Further optimization: particles of different particle sizes need to be adsorbed by different electric fields. The control logic of the electric field component of the adsorption area is: when the workpiece moves to the lower part of the adsorption area (the area covered by the B particle layer), the high-voltage pulse electric field is started. The high-voltage pulse electric field overcomes the inertia of the B particles (kinetic energy Ek = 0.5mv) through the instantaneous strong field. 2 ), forcing large particles to be quickly adsorbed to the surface of the workpiece. Exemplarily, the parameters of the high-voltage pulse electric field are: electric field strength: -100kV / m (negative polarity inhibits electrostatic repulsion); pulse frequency: 200Hz (duty cycle 50%); action time: 0.1-0.3 seconds (adaptively adjusted according to the thickness of the B particle layer). When the workpiece enters the upper part of the adsorption area (the area covered by the A particle layer), it switches to a steady-state gradient electric field. The gradient electric field guides the small particles (A particles) to deposit layer by layer along the direction of the electric field lines through a slowly varying field intensity distribution, filling the gaps between the B particles and avoiding dispersion caused by Brownian motion. Exemplarily, the parameters of the steady-state gradient electric field are: electric field strength: -60kV / m (negative polarity); gradient direction: linearly decreasing from top to bottom (gradient value ); action time: 0.5-1.0 seconds (dynamically adjusted according to the suspension density of particle A). In the obtuse angle motion path, the workpiece coordinates are monitored in real time by the position sensor (encoder accuracy ±0.01mm) to trigger the electric field mode switching. When the workpiece enters the B particle area: the electrode plate array is loaded with pulsed high voltage (rise time <1ms); the ultrasonic standing wave field is synchronously turned off (to avoid sound pressure interference). When the workpiece enters the A particle area: the electrode plate switches to gradient voltage output (analog-to-digital converter resolution 16bit); the ultrasonic standing wave field is restarted (frequency 20kHz) to disperse the A particle agglomerates through microscopic vibration. Dynamic parameter optimization: According to the A / B particle density (unit: g / m 3 ), dynamically adjust the electric field parameters: For example: if the B particle density is >50g / m 3 , increase the pulse electric field intensity; if the Span value of particle A is greater than 1.5, increase the gradient electric field span. A closed-loop control algorithm (PID adjustment coefficients Kp = 0.8, Ki = 0.2, Kd = 0.1) ensures real-time matching of electric field parameters and particle distribution.

[0082] In order to further improve the hanging spraying method, the following steps are added after step S6:

[0083] S7: A negative pressure recovery device is set on the side of the adsorption zone away from the stratification zone to recover the unattached A particles and B particles.

[0084] Specifically, in order to recover unadsorbed particles, an inverted cone-shaped recovery chamber (cone angle 60°, material 316L stainless steel) is set at the end of the adsorption zone. The top of the chamber is connected to a high-pressure centrifugal fan, and a dual-channel separator is set at the bottom: Particle recovery channel A: The inner wall is coated with Teflon (friction coefficient <0.05), and the end is connected to a cyclone separator; Particle recovery channel B: Built-in electrostatic adsorption plate, the end is connected to a bag filter (PTFE coated filter material, filtration accuracy 0.3μm). CFD simulation is used to determine the inclination angle (35°) and spacing (120mm) of the guide plate to form a stable velocity gradient in the cavity: the flow rate in the center area is 8m / s (to ensure rapid sinking of particles); the flow rate in the edge area is 0.5m / s (to suppress secondary dust). The difference in particle size between A and B particles is used to achieve centrifugal classification in the cyclone separator to ensure that A particles are completely captured and B particles enter the electrostatic channel. The A particles collected by the cyclone separator are de-agglomerated by the vibrating screen and then returned to the feed tank by pneumatic conveying. The static electrode plate automatically scrapes off the B particles every hour. After ultrasonic dispersion, they are mixed with new materials in a certain proportion and fed into the single rotary cup.

[0085] The beneficial effects of this embodiment include:

[0086] ① This technical solution adds magnetic nanoparticles to the coating so that the atomized coating can be driven by the magnetic field, and then the larger B particles are driven to the lower part of the stratification zone through the gradient magnetic field, and the smaller A particles are driven to the upper part of the stratification zone through the air pressure difference, thereby realizing the stratification of large and small particles, obtaining A particle layer and B particle layer, and then by driving the workpiece along the second direction through the area covered by the B particle layer and the area covered by the B particle layer in the adsorption zone, the larger B particles are first adsorbed onto the workpiece under the action of the electric field, and then the smaller A particles are adsorbed onto the workpiece under the action of the electric field. By first adsorbing the larger particles, local accumulation caused by gravity or airflow disturbance after mixing with the smaller particles is avoided, thereby reducing the uneven defects on the coating surface and improving the uniformity of the spraying.

[0087] ② The preferential adsorption of larger particles can reduce their circulation loss in the recovery system, while the extended suspension time of small particles improves the adsorption efficiency. In addition, step-by-step adsorption allows independent optimization of parameters to avoid uneven coating caused by parameter conflicts.

[0088] ③Through step-by-step adsorption, particles with larger particle sizes are first stably deposited on the bottom layer, and particles with smaller particle sizes are then driven by the electric field to fill the gaps, forming a continuous coating and effectively reducing the standard deviation of the coating.

[0089] ④ The preferentially adsorbed particles with larger particle size can be arranged in a directional manner through the template effect to reduce the discreteness of the mirror reflection angle. The dense layer formed after the particles with smaller particle size are filled can shorten the optical path, inhibit multiple scattering, and improve the gloss.

[0090] ⑤ Through step-by-step adsorption, the contact time can be shortened, thereby reducing the "crater" effect of particles with larger particle sizes. By extending the adsorption time, small particles can fully fill the gaps between particles with larger particle sizes, thereby improving the utilization rate of the coating.

[0091] Example 2

[0092] An embodiment of the present invention provides a hanging spraying device, comprising:

[0093] A spray chamber and a hanging assembly; the spray chamber includes an atomization zone, a stratification zone and an adsorption zone distributed in sequence along a first direction; the atomization zone is provided with a single rotary cup; the stratification zone is provided with a magnetization assembly, an air intake system and an air exhaust system; the adsorption zone is provided with an electric field assembly; the hanging assembly is used to drive the workpiece through the adsorption zone along a second direction.

[0094] Specifically, this device achieves precise particle stratification and directional adsorption through a three-section spatial design of atomization zone, stratification zone, and adsorption zone, combined with the synergistic effect of magnetic, gas, and electric fields. The spray chamber is divided into the atomization zone, stratification zone, and adsorption zone along the first direction (horizontal direction). The functional modules of each zone are as follows:

[0095] Atomization area: Core components: Single-cup atomizer: uses high-speed electrostatic cup (speed range 0-50,000rpm), equipped with anti-splash start logic, built-in temperature sensor and speed feedback system. Preheating system: Paint storage tank with integrated electric heating jacket (temperature control accuracy ±1°C), combined with online viscometer (Brookfield DV3T), real-time monitoring of paint viscosity. Electrostatic generator: high-voltage DC power supply, charge-to-mass ratio monitoring probe (accuracy ±5%), triggering feeding suspension in case of abnormality. The preheating system ensures the fluidity of the paint. The single-cup breaks the mixed paint into uniformly charged atomized particles through the synergistic effect of centrifugal force and high-voltage electric field. The electrostatic generator charges the particles (charge-to-mass ratio 1.2×10 -4 C / kg), enhancing the subsequent adsorption efficiency.

[0096] Layered Zone: Magnetization Assembly: Permanent Magnet Array: Utilizes a Halbach structure (NdFeB N52), with a wedge-shaped magnetic plate (pure iron DT4C, wedge angle 15°) placed on top, creating a linearly decreasing gradient magnetic field from top to bottom (divergence angle <2.5°). Electromagnetic Coil: Double-layer winding design, located at the bottom of the layered zone. Current is regulated by a PLC (ΔI = 0.1A / 0.01T deviation) to correct the magnetic field gradient. Air Path System: Intake System: A porous gas distribution plate (pore diameter 0.5mm) at the bottom is connected to a centrifugal fan (variable frequency control ±0.01Hz), with PID control of the intake speed. Exhaust System: A top annular exhaust hood is equipped with a variable frequency induced draft fan, which forms an upward net airflow with the intake system (airflow ratio 1.05:1). A honeycomb rectifier is used to reduce turbulence intensity (turbulence intensity <3%). Monitoring and feedback: Online laser particle size analyzer: Install a 45° inclined quartz observation window, which outputs Dv10, Dv50, Dv90 and Span values in real time based on Mie scattering. The data is closed-loop controlled by PLC to control the magnetic field and airflow. Gradient magnetic field ) drives large particles (particles B) downward, while upward airflow (Stokes force F_a = 3πμd_p(v_g - v_p)) lifts small particles (particles A) into suspension, achieving particle size stratification (overlap area ≤ 15%). Real-time particle size feedback dynamically adjusts magnetic field strength and airflow velocity to ensure stratification stability.

[0097] Adsorption area: Suspension control: Anti-gravity air curtain: The bottom annular slit nozzle (compressed air pressure 0.5MPa) forms a conical air curtain (V(z)=V0·e -kz ) to offset the gravity sedimentation of particles; Ultrasonic standing wave field: The top piezoelectric transducer array (frequency 20kHz) cooperates with the bottom reflector to generate a standing wave field with a sound pressure level of ≥140dB, inhibiting particle agglomeration. Hanging assembly: Six-axis robotic arm: Repeatability accuracy ±0.005mm, integrated six-dimensional force sensor at the end, moving along a 135° inclined guide rail (speed 0.5-1.2m / s); Compound trajectory control: Motion trajectory formula v x (t) = k·v z +W·sin(2πft+φ), dynamically adjusting the k and W parameters in conjunction with feedback from the coating thickness gauge; Adaptive fixture: A composite structure of vacuum suction cups and mechanical locking to accommodate irregular-shaped workpieces; Motion controller: Linked with the robotic arm, electric field assembly, and injection valve to achieve closed-loop control of "speed-flow-electric field." Electric field assembly: Electrode plate array: Applies a -80kV high-voltage electric field to drive particles to be adsorbed onto the workpiece surface in a targeted manner. Fluxgate sensor array: Equally spaced along the height, monitoring magnetic field linearity (error ≤1.8%). The anti-gravity air curtain and ultrasonic field collaborate to achieve zero-gravity suspension of particles. The robotic arm's obtuse-angle motion extends adsorption time, and the composite trajectory optimizes coating uniformity. The workpiece moves in a second direction (at an obtuse angle of 135° to the first direction), with the robotic arm's motion phase-locked with the particle injection to ensure uniform coating coverage.

[0098] Optimized, a negative pressure recovery component is also provided at the end of the adsorption zone, specifically including an inverted cone recovery chamber and a dual-channel separator. The inverted cone recovery chamber is made of 316L stainless steel (cone angle 60°), with a built-in 35° guide plate (spacing 120mm), and the center flow velocity is greater than the edge flow velocity. Dual-channel separator: A particle channel: Teflon-coated inner wall + cyclone separator (separation efficiency ≥ 99%). B particle channel: electrostatic adsorption plate (voltage -15kV) + PTFE-coated bag filter (precision 0.3μm). The particles are recovered by graded recovery based on particle size differences. Particle A is pneumatically conveyed for reuse, and particle B is ultrasonically dispersed and mixed with new materials to improve the recovery rate.

[0099] The device's workflow is as follows: Atomization: The preheated mixed coating is atomized by a single rotary cup, and the charged particles enter the stratification zone. Stratification: A gradient magnetic field and airflow collaborate to separate the A / B particles by size, with a laser particle size analyzer providing real-time feedback and parameter adjustments. Adsorption: Particles are suspended in a counter-gravity field, while the workpiece moves along an obtuse angle, optimizing the coating structure through a composite trajectory. Recovery: Unadsorbed particles are recovered through negative pressure grading for recycling.

[0100] Through partitioned modular design and intelligent closed-loop control, this device achieves high-precision layered spraying of magnetic nano-coatings, uniform coating thickness, and improved material utilization.

[0101] Example 3

[0102] An embodiment of the present invention further provides a computer-readable storage medium, in which a computer program is stored, and when the computer program is executed by a processor, the hanging spraying method of embodiment one is implemented. The computer-readable storage medium can be any available medium that a computing device can store or a data storage device such as a data center containing one or more available media. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a high-density digital video disc (DVD)), or a semiconductor medium (for example, a solid-state hard disk), etc. The computer-readable storage medium includes instructions that instruct the computing device to execute any one of the hanging spraying methods provided in embodiment one.

[0103] Example 4

[0104] An embodiment of the present invention further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory;

[0105] The processor executes the computer program to implement the hanging spraying method in the first embodiment.

[0106] Those skilled in the art can clearly understand that for the convenience and brevity of description, other working processes of the method described above can refer to the corresponding processes in the aforementioned embodiments and will not be repeated here.

[0107] Through the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course can also be implemented by special hardware including application-specific integrated circuits, special CPUs, special memories, special components, etc. In general, all functions performed by computer programs can be easily implemented with corresponding hardware, and the specific hardware structures used to implement the same function can also be various, such as analog circuits, digital circuits or special circuits, etc. However, for the present application, software program implementation is a better implementation method in most cases. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer's floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk or optical disk, etc., and includes a number of instructions to enable a computer device (which can be a personal computer, training equipment, or network equipment, etc.) to execute the methods of each embodiment of the present application.

[0108] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

[0109] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, computer, training equipment or data center to another website, computer, training equipment or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a training equipment, data center, etc. that includes one or more available media integrations. Available media can be magnetic media, (e.g., floppy disk, hard disk, tape), optical media (e.g., DVD), or semiconductor media (e.g., solid-state drive (SSD)), etc.

[0110] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A hanging spraying method, characterized in that: include: S1: adding magnetic nanoparticles to the coating to obtain a mixed coating; S2: atomizing the mixed coating in the atomization zone of the spraying chamber through a single rotary cup to obtain mixed particles; S3: driving the mixed particles to move in a first direction into a stratification zone of a spraying chamber; S4: dividing the mixed particles into a particle layer A and a particle layer B in a stratified region by a magnetic field and a pressure difference, wherein the particle size range of the A particles in the particle layer A at the upper portion of the stratified region is (a, A), and the particle size range of the B particles in the particle layer B at the lower portion of the stratified region is (b, B), wherein A < B, and the overlapping range of (a, A) and (b, B) is less than or equal to 15% of (a, B); S5: driving the A particle layer and the B particle layer to move in a first direction into an adsorption area of a spraying chamber; S6: Control the workpiece to move along a second direction through the adsorption area, where the second direction forms an obtuse angle with the first direction.

2. A hanging spraying method according to claim 1, characterized in that: The step of dividing the mixed particles into particle layer A and particle layer B by using a magnetic field and air pressure difference in the stratified region comprises: The gradient magnetic field is used to force the B particles to sink, and the upward airflow is used to lift the A particles into suspension. The gradient magnetic field is from top to bottom and the magnetic field direction is vertically downward. The airflow is generated by the air intake system located at the bottom of the stratification area and the air exhaust system located at the top of the stratification area.

3. A hanging spraying method according to claim 2, characterized in that: The gradient magnetic field constrains the divergence angle of the magnetic flux lines to be ≤3° through the wedge-shaped magnetic conductive plate, and the magnetic field linearity error is ≤2%.

4. A hanging spraying method according to claim 1, characterized in that S6 include: S61: offsetting the gravitational settling of particles A and B by counteracting the gravity air curtain and ultrasonic standing waves; S62: Control the workpiece to move along a second direction through the adsorption area, where the second direction forms an obtuse angle with the first direction.

5. The hanging spraying method according to claim 1, characterized in that: The motion trajectory formula of the workpiece in the adsorption area is: x (t)=k⋅v z +W⋅sin(2πft+ϕ); Where: v x is the instantaneous moving speed of the workpiece in the X direction, which is opposite to the first direction, v z is the main motion velocity in the Z direction, which is perpendicular to the X direction. k is the linear coupling coefficient between the X-direction velocity and the Z-direction velocity, which is dimensionless. k = tanθ, θ is the angle between the second direction and the X direction, W is the amplitude of the periodic disturbance, f is the disturbance frequency, ϕ is the initial phase angle, and t is the time variable.

6. A hanging spraying method according to claim 1, characterized in that: S6 and later also include: S7: A negative pressure recovery device is set on the side of the adsorption zone away from the stratification zone to recover the unattached A particles and B particles.

7. A hanging spraying method according to claim 1, characterized in that: The S4 also includes: S41: Detecting the particle size distribution of the mixed particles by a laser particle size analyzer; S42: adjusting the intensity of the gradient magnetic field and the speed of the upward airflow according to the particle size distribution.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory, wherein: The processor executes the computer program to implement the steps of the hanging spraying method according to any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the hanging spraying method according to any one of claims 1 to 7 are implemented.

10. A hanging spraying device for executing the hanging spraying method according to any one of claims 1 to 7, characterized in that: include: spray booths and rigging assemblies; The spray chamber includes an atomization zone, a stratification zone and an adsorption zone sequentially distributed along a first direction; The atomization area is provided with a single rotary cup; The stratified area is provided with a magnetization component, an air intake system and an air extraction system; The adsorption area is provided with an electric field component; The hanging assembly is used to drive the workpiece to pass through the adsorption area along the second direction.

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