Automatic grinding method and system for drum-shaped rotary filter screen of nuclear power station

Abstract

The invention discloses an automatic grinding method and system for a drum-shaped rotary filter screen of a nuclear power station, and relates to the technical field of nuclear power equipment maintenance. Comprising a base and a mechanical arm arranged on the base. The polishing head is arranged at the front end of the mechanical arm; the detection part is arranged on the mechanical arm, and the detection part replaces a grinding head based on an algorithm and parameters preset by the system; after the mechanical arm moves to the to-be-polished area A, a specific relative position relation is formed between the front end of the mechanical arm and the to-be-polished area A. According to the device, the polishing head can reach the position where traditional polishing cannot be achieved through the mechanical arm, polishing process parameters are adjusted through the control system, the polishing head is attached to the surface of the filter screen spoke, surface cleaning is conducted on the to-be-polished area of the filter screen spoke, corrosion products, marine organisms and the like attached to the surface are removed, and it is ensured that the polished surface is dry. And after polishing is completed, the polishing effect is checked through an infrared scanning system, and it is ensured that the surfaces of the filter screen spokes meet the expected polishing quality requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power equipment maintenance, and in particular to an automatic grinding method and system for a drum-shaped rotary filter screen of a nuclear power plant. Background Art

[0002] Drum-type rotary screens are essential water filtration equipment in the water supply systems of large thermal power plants and nuclear power plants. They effectively remove vegetation, fish, shrimp, and other debris larger than the mesh size. Developed from plate-and-frame rotary screens, drum screens are mechanical filtration devices specifically suited for circulating cooling water in large thermal and nuclear power plants. They offer stable operation, reliable sealing, high water flow rates, and minimal wear parts, making them widely used in my country. In nuclear power cooling systems, drum-type rotary screens are crucial for ensuring safe unit operation, and their functional integrity directly determines the filtration efficiency and heat exchange performance of the cooling water system. However, over long-term service, scale deposits on the filter surface, caused by seawater impurities, biofouling, and electrochemical corrosion, can significantly increase flow resistance and can also cause problems such as filter blockage and drive mechanism overload, seriously threatening nuclear power plant operation.

[0003] At present, nuclear power plants at home and abroad generally use manual grinding to remove filter scale, but this mode has the following problems: 1) Manual grinding is inefficient (a single maintenance cycle is as long as more than 72 hours), which cannot meet the high-density maintenance needs of nuclear power plants; 2) Due to the influence of the internal and external corners and complex curved surfaces of steel profiles, it is difficult to fully cover the surface, and there are blind spots in grinding; 3) The quality of grinding is greatly affected by factors such as operator skills and on-site environment, and the surface roughness deviation is >15%; 4) There is a risk of radioactive contamination in the working environment, and the safety hazards of manual operation are prominent. Summary of the Invention

[0004] In view of the problems existing in the above-mentioned automatic grinding method of the existing nuclear power plant drum rotary filter, the present invention is proposed.

[0005] Therefore, the present invention provides an automatic grinding method for a nuclear power plant drum-shaped rotary filter, the purpose of which is to solve the problems existing in the manual grinding of the existing nuclear power drum-shaped rotary filter.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: a method for automatically polishing a drum-shaped rotary filter screen for a nuclear power plant, comprising scanning and collecting point cloud data of the filter screen spokes, meshing the point cloud data, and extracting key feature points;

[0007] Based on point cloud data, a multi-node quintic polynomial equation is used to describe the tracking trajectory;

[0008] Establish a fitness function, calculate the fitness value of each particle, introduce constraints, update the individual optimum and the global optimum, and after the iteration, take the path corresponding to the individual optimum as the final polishing trajectory.

[0009] As a preferred solution of the automatic grinding method of the nuclear power plant drum rotary filter described in the present invention, the key feature points include three-dimensional scanning of the area to be ground, obtaining point cloud data, mapping the point cloud data to a grid coordinate system, and identifying the position and morphological features of the area to be ground.

[0010] As a preferred solution of the automatic grinding method of the nuclear power plant drum rotary filter of the present invention, the fitness function is expressed as:

[0011] F=α·1 / L+β·C+γ·1 / F u

[0012] where α, β, and γ are weight coefficients, L is the path length, C is the coverage, and F is the degree of fluctuation of the force applied by the grinding head during the grinding process.

[0013] As a preferred solution of the automatic grinding method for the drum-shaped rotary filter screen of a nuclear power plant according to the present invention, the introduced constraint conditions include that the path must be continuous and the distance between adjacent points must be less than or equal to the single-step movement threshold of the robot arm;

[0014] Output the optimal path. After the iteration is completed, take the path corresponding to gbest as the final polishing trajectory.

[0015] As an optimal solution for the automatic grinding method of the nuclear power plant drum rotating filter described in the present invention, a multi-node fifth-order polynomial equation is used to describe the motion trajectory of the robotic arm, constraints and function mechanisms are introduced, trajectory parameters are optimized, and the trajectory compliance is verified by solving the equation to generate the optimal motion trajectory.

[0016] As a preferred solution of the automatic grinding method of the nuclear power plant drum rotary filter of the present invention, the particle group is initialized and the initial particle size is randomly generated to cover all areas to be ground.

[0017] As a preferred solution of the nuclear power plant drum rotating filter path optimization system described in the present invention, it introduces constraints and function mechanisms, optimizes trajectory parameters, verifies trajectory compliance by solving equations, and generates the optimal motion trajectory.

[0018] As a preferred solution of the nuclear power plant drum rotating screen path optimization system of the present invention, the PSO speed formula is expressed as:

[0019]

[0020] in, and The speed of particle i at the kth iteration and the speed at the k+1th iteration. The speed determines the direction and step size of the particle movement and is a multidimensional vector; w: controls the influence of the previous moment's speed on the current speed. When w is large, the particle tends to explore globally, and when w is small, the particle tends to develop locally. c1 and c 2： They are cognitive coefficient and social coefficient respectively. c1 represents the tendency of particles to move to their own historical optimal position, and c2 represents the tendency of particles to move to the historical optimal position of the group. The typical value is c1=c2=2, but it needs to be adjusted according to the problem. r1 and r 2： Random numbers are uniformly distributed in the interval (0, 1). Randomness is introduced to prevent the algorithm from falling into local optimality and are regenerated in each iteration.

[0021] As a preferred solution of the nuclear power plant drum rotating filter path optimization system of the present invention, wherein: a scanning module collects three-dimensional point cloud data of the filter surface; a data processing module pre-processes, meshes and extracts features of the collected point cloud data;

[0022] The communication module transmits the processed data to the control system for path planning and grinding execution.

[0023] As a computer-readable storage medium of the present invention, a computer program is stored thereon, characterized in that when the computer program is executed by a processor, the steps of the automatic grinding method of the nuclear power plant drum rotary filter as described in any one of claims 1 to 8 are implemented.

[0024] The beneficial effects of this invention include: a robotic arm enables the grinding head to reach locations inaccessible by traditional grinding methods. A control system adjusts grinding process parameters to ensure that the grinding head conforms to the surface of the filter spokes. This cleans the surface of the filter spokes to be polished, removing corrosion products and marine growth, ensuring a dry polished surface. Upon completion, an infrared scanning system checks the polishing results to ensure that the surface of the filter spokes meets the desired polishing quality requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0026] Figure 1 It is a schematic diagram of the overall structure of the automatic grinding method of the nuclear power plant drum rotary filter of the present invention.

[0027] Figure 2 The present invention is a flowchart of the automatic grinding method for a nuclear power plant drum rotary filter.

[0028] Figure 3 This is an operational flow chart of the path optimization system of the present invention. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it individually or selectively refer to an embodiment that is mutually exclusive of other embodiments.

[0032] Furthermore, the present invention is described in detail with reference to schematic diagrams. For ease of illustration, when describing the embodiments of the present invention, cross-sectional views illustrating device structures may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of protection of the present invention. Furthermore, in actual production, the three-dimensional dimensions of length, width, and depth should be included.

[0033] Example 1

[0034] Reference Figure 1 - Figure 2 , which is the first embodiment of the present invention, provides a method for automatically grinding a drum-shaped rotary filter screen in a nuclear power plant, wherein the robot arm 2 includes a large arm 21 and a small arm 22, the small arm 22 is rotatably arranged on the base 1, the small arm 22 is rotatably arranged at the end of the large arm 21, and the end of the small arm 22 is connected to the grinding head 3 through a flange, the detection part 4 includes a controller 41 and a scanner 42, the controller 41 processes the data collected by the scanner 42, and drives the grinding head 3 to grind

[0035] The grinding device is fixed to the drum-shaped rotating filter of the nuclear power plant through a magnetic bottom and a fixed buckle. The upper arm 21 is responsible for rotation. The upper arm 21 is connected to the base 1 through a connecting mechanism. It mainly undertakes the rotation function and adjusts the overall angle and position of the grinding device so as to move the grinding head 3 to the area that needs to be polished. The small arm 22 is responsible for extension and retraction. The small arm 22 is connected to the upper arm 21 through a connecting mechanism, and the front end is connected to the grinding head 3 through a flange. The extension function of the small arm 22 is used to adjust the distance between the grinding head 3 and the grinding area to ensure that the grinding head 3 can accurately contact and polish the target area.

[0036] Furthermore, after the robot arm 2 moves to the area to be polished A, a specific relative position relationship is formed between the front end of its small arm 22 and the polishing area A. Then, the infrared laser scanner 42 on the small arm 22 is used to scan the area to be polished. Based on the preset algorithm and parameters, the robot arm 2 automatically matches and selects the appropriate polishing head 3. A flat polishing head 3 is used for large flat areas, and a cylindrical or conical polishing head 3 is used for angular areas.

[0037] Among them, the grinding head 3 is connected to the flange through adsorption, and the rear end spring controls the pressure with the contact surface, and the pressure parameters are adjusted in real time during the grinding process.

[0038] Furthermore, an infrared laser scanner 42 is used to collect the position information of the filter spokes, and the collected data is divided into a network. The polishing path is planned based on the point cloud data, and the optimal polishing rotation route is formulated using the logical process of path generation. The fitness function of the tracking trajectory and the polishing path is established for the trajectory planning model based on the particle swarm algorithm. Constraints are established and a penalty function mechanism is introduced. A multi-node fifth-order polynomial equation is used to describe the tracking trajectory. The equation is solved to determine whether the motion parameters meet the constraints. The tracking trajectory is optimized to obtain the optimal solution. An exit mechanism is introduced in combination with the particle swarm algorithm to sort the path points to obtain the time-optimal polishing path.

[0039] After the controller 41 processes the data, a driving command is issued to the robot arm 2, which adopts a zigzag route. The grinding speed of the repeated area is fast and the contact pressure is small.

[0040] Example 2

[0041] For grinding of flat areas, there are large flat areas on the surface of the arc-shaped rotating filter in the nuclear power plant that need to be ground.

[0042] The infrared laser scanner 42 scans the plane area and generates point cloud data. The system divides the grid according to the point cloud data, plans a zigzag grinding path, selects the plane grinding head 3, connects it through an adsorption flange, and adjusts the spring pressure to adapt to the plane contact. The upper arm 21 rotates to move the grinding device to the target area; the lower arm 22 extends and retracts to adjust the distance between the grinding head 3 and the surface. The controller 41 drives the grinding head 3 to grind according to the planned path. During the grinding process, the system monitors the pressure parameters in real time to ensure uniform grinding.

[0043] The rotation angle of the upper arm 21 is optimized by a fifth-order polynomial equation, and the extension and retraction distance of the lower arm 22 is dynamically adjusted according to the surface height to avoid excessive pressure.

[0044] Example 3

[0045] Grinding of the corner areas: The edges or corner areas of the curved rotating filter in the nuclear power plant need to be finely ground.

[0046] The infrared laser scanner 42 scans the angular area to identify the position and shape of the angular area. The system selects a cylindrical or conical grinding head 3 based on the scanning data, plans a grinding path for the angular area, and adopts a segmented grinding strategy. The upper arm 21 rotates to position the grinding device to the angular area; the lower arm 22 extends and retracts to ensure that the grinding head 3 is in full contact with the angular area. The controller 41 controls the grinding head 3 to perform grinding according to the planned path, and adjusts the spring pressure in real time to avoid excessive grinding or damage to the angular area.

[0047] The rotation angle of the upper arm 21 and the extension and retraction distance of the lower arm 22 are optimized by the particle swarm algorithm to ensure efficient positioning. A jump-out mechanism is introduced to optimize the sorting of path points and reduce the time for polishing edges and corners.

[0048] Example 4

[0049] For complex curved surface grinding, the surface of the nuclear power plant drum-shaped rotating filter has complex curved surfaces and requires high-precision grinding.

[0050] The infrared laser scanner 42 performs an all-round scan of the complex surface to generate high-density point cloud data. The system divides the point cloud data into fine grids, plans the three-dimensional grinding path, and dynamically selects the grinding head 3 (plane, cylindrical or conical) according to the shape of the surface. The upper arm 21 rotates to position the grinding device to the curved surface area; the lower arm 22 extends and retracts to adjust the distance between the grinding head 3 and the curved surface, and the controller 41 drives the grinding head 3 to grind according to the three-dimensional path.

[0051] During the grinding process, the pressure and movement speed of the grinding head 3 are adjusted in real time to ensure that the curved surface is evenly ground. The remaining structures are the same as those of Examples 2 and 3.

[0052] Example 5, with reference to Figure 3 , which is the third embodiment of the present invention. This embodiment is different from the second embodiment in that it is based on particle swarm algorithm tracking trajectory optimization.

[0053] The filter surface is discretized into a grid (e.g., 100×100 lattice), each grid point represents a possible polishing point, and each particle represents a possible polishing path. The path consists of a grid point sequence, such as [P1, P2, Pn], where Pi is the grid point coordinate.

[0054] Fitness function: used to evaluate the quality of the path, taking into account the path length, coverage and grinding force stability: Fitness function:

[0055] L: Path length, which represents the total distance the grinding head moves during the entire grinding process. The shorter the path, the greater the 1 / L ratio, indicating a better path.

[0056] C: Coverage rate, which indicates the proportion of the area to be polished covered by the grinding head. The higher the coverage rate, the larger C is, indicating that no area is missed in the grinding.

[0057] F: Force fluctuation variance, which indicates the degree of fluctuation in the force applied by the grinding head during the grinding process. The smaller the force fluctuation, the larger the 1 / F, indicating a more stable grinding process.

[0058] α, β, γ: weight coefficients used to balance the importance of path length, coverage, and force fluctuation variance.

[0059] For example, α = 0.5, β = 0.3, and γ = 0.2 indicate that path length is of the highest importance, coverage is second, and force fluctuation variance is the lowest.

[0060] Algorithm execution process

[0061] The initial path is randomly generated to ensure that all the areas to be polished are covered. The initial position and speed of each particle are randomly generated.

[0062] Calculate the fitness value of each particle and update the individual best (pbest) and global best (gbest).

[0063] The PSO speed formula is expressed as:

[0064]

[0065] and The velocity of particle i at the kth iteration and the k+1th iteration. The velocity determines the direction and step size of the particle's movement and is a multidimensional vector.

[0066] w: controls the influence of the previous moment's speed on the current speed. When w is large, particles tend to explore globally, and when w is small, particles tend to develop locally.

[0067] c1 and c 2： They are the cognitive coefficient and the social coefficient, c1 represents the tendency of the particle to move to its own historical optimal position, and c2 represents the tendency of the particle to move to the historical optimal position of the group. The typical value is c1=c2=2, but it needs to be adjusted according to the problem.

[0068] r1 and r 2： Random numbers are uniformly distributed in the interval (0, 1). Randomness is introduced to prevent the algorithm from falling into local optimality and are regenerated in each iteration.

[0069] Introduce constraints: the path must be continuous and the distance between adjacent points must be ≤ the single-step movement threshold of robot arm 2 to ensure the feasibility of the path.

[0070] After the iteration is completed, the path corresponding to gbest is taken as the final polishing trajectory. The rest of the structure is the same as that of Example 2.

[0071] Finally, the algorithm dynamically controls the polished filter screen by taking photos and inspecting them through infrared laser scanning, monitoring the polishing effect in real time, and adjusting the polishing process parameters (such as polishing speed and pressure) in real time through the PLC based on the inspection results. The position of the robot arm 2 is also dynamically adjusted to ensure the polishing speed and the contact pressure of the polishing head 3, thereby improving the polishing efficiency and quality. After the polishing of the current area is completed, the above action is repeated to polish the next area until the entire filter surface is polished.

[0072] The advantages of this algorithm are: by optimizing the path length, the idle travel time of the robot arm 2 is reduced, and the grinding efficiency is improved; it ensures that the dirt areas on the filter surface are not missed and avoids duplication or omission; it adapts to the protrusions or structural mutation areas on the filter surface to avoid collisions between the robot arm 2 and the filter.

[0073] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for automatically polishing a drum-shaped rotary filter screen in a nuclear power plant, characterized by: include, Scan and collect point cloud data of the filter spokes, mesh the point cloud data, and extract key feature points; Based on point cloud data, a multi-node quintic polynomial equation is used to describe the tracking trajectory; Establish a fitness function, calculate the fitness value of each particle, introduce constraints, update the individual optimum and the global optimum, and after the iteration, take the path corresponding to the individual optimum as the final polishing trajectory.

2. The automatic grinding method for a nuclear power plant drum-shaped rotary filter according to claim 1, characterized in that: The key feature points include performing a three-dimensional scan of the area to be polished, obtaining point cloud data, mapping the point cloud data to a grid coordinate system, and identifying the position and topographic features of the area to be polished.

3. The automatic grinding method for a nuclear power plant drum-shaped rotary filter according to claim 1, characterized in that: The fitness function is expressed as: F=α·1L+β·C+γ·1F u where α, β, and γ are weight coefficients, L is the path length, C is the coverage, and F is the degree of fluctuation of the force applied by the grinding head during the grinding process.

4. The automatic grinding method for a nuclear power plant drum-shaped rotary filter according to claim 3, characterized in that: The introduced constraint conditions include that the path must be continuous and the distance between adjacent points must be less than or equal to the single-step movement threshold of the robot arm; Output the optimal path. After the iteration is completed, take the path corresponding to gbest as the final polishing trajectory.

5. The automatic grinding method for a nuclear power plant drum-shaped rotary filter according to claim 4, characterized in that: A multi-node quintic polynomial equation is used to describe the motion trajectory of the robotic arm. Constraints and function mechanisms are introduced to optimize the trajectory parameters. The trajectory compliance is verified by solving the equations to generate the optimal motion trajectory.

6. The automatic grinding method for a nuclear power plant drum-shaped rotary filter according to claim 5, characterized in that: Initialize the particle swarm and randomly generate the initial particle size to cover all areas to be polished.

7. The automatic grinding method for a nuclear power plant drum-shaped rotary filter according to claim 5, characterized in that: Constraints and function mechanisms are introduced to optimize trajectory parameters, and trajectory compliance is verified by solving equations to generate the optimal motion trajectory.

8. The automatic grinding method for a nuclear power plant drum-shaped rotary filter according to claim 7, characterized in that: The PSO speed formula is expressed as: in, and The velocity of particle i at the kth iteration and the k+1th iteration. The velocity determines the direction and step size of the particle's movement and is a multidimensional vector. w : Controls the influence of the previous moment's speed on the current speed. When w is large, particles tend to explore globally, and when w is small, particles tend to develop locally. c1 and c2: cognitive coefficient and social coefficient respectively, c1 represents the tendency of particles to move towards their own historical optimal position, and c2 represents the tendency of particles to move towards the historical optimal position of the group; r1 and r2: Random numbers uniformly distributed in the interval (0,1). Randomness is introduced to prevent the algorithm from falling into local optimality. They are regenerated in each iteration.

9. An automatic grinding system for a nuclear power plant drum-shaped rotating filter screen, using the automatic grinding method for a nuclear power plant drum-shaped rotating filter screen according to any one of claims 1 to 8, characterized in that: include: Scanning module, collecting 3D point cloud data of the filter surface; Data processing module, which performs pre-processing, meshing and feature extraction on the collected point cloud data; The communication module transmits the processed data to the control system for path planning and grinding execution.

10. 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 method for automatically grinding a drum-shaped rotary filter screen in a nuclear power plant as described in any one of claims 1 to 8 are implemented.

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