Method and system for detecting uniformity of thickness of high-wear-resistance bathroom PVD coating layer

Abstract

The embodiment of the specification provides a high-wear-resistance bathroom PVD coating layer thickness uniformity detection method and system, the method comprises the following steps: obtaining a workpiece three-dimensional model and dividing a surface element, combining a PVD source position, a workpiece posture and a clamp rotation information to establish a discrete posture, determining a reachable state of each surface element, and determining a detection partition and a partition boundary according to a difference in a reachable state sequence of adjacent surface elements. According to the detection partition, the partition boundary and the surface curvature, a vortex thickness scanning path is generated and film thickness data is collected, and only the measured data in the same detection partition is used for film thickness interpolation; then, according to the boundary film thickness difference, the film thickness change rate and the unmeasured area, a supplementary scanning path is generated and re-measured, and finally a three-dimensional thickness distribution is generated and an abnormal film thickness area is identified.

Description

Technical Field

[0001] The embodiments described in this specification relate to the field of PVD coating quality testing technology, specifically to a method and system for testing the uniformity of thickness of a high wear-resistant sanitary ware PVD coating layer. Background Technology

[0002] Physical vapor deposition (PVD) can form thin films on metal surfaces that combine decorative, wear-resistant, and corrosion-resistant properties, and has been used for surface treatment of bathroom hardware such as faucets, showerheads, and handles. With increasing demands for product appearance consistency and durability, film thickness uniformity has become a crucial indicator affecting the quality of PVD coatings. Existing film thickness measurement methods include cross-sectional microscopy, ball milling, X-ray fluorescence, and non-destructive thickness measurement based on electromagnetic properties. Destructive methods are mostly used for sampling verification, while non-destructive thickness measurement is more suitable for production testing. Actual bathroom hardware often has complex structures such as curved surfaces, grooves, and steps. During the coating process, the workpiece also undergoes rotation and posture changes. Different surfaces have different orientations and shielding relationships with the PVD source, easily leading to localized film thickness differences.

[0003] Current manual or automated thickness measurement methods typically scan at preset measurement points or fixed intervals, with the detection location primarily determined by geometry. This approach fails to adequately consider the differences in actual accessibility conditions for different surface regions during the coating process. Furthermore, thickness estimation or interpolation is required between limited measurement points on complex curved surfaces. Reconstructing thickness across abrupt changes in thickness can weaken the true thickness step. Fixed scanning densities also struggle to simultaneously cover high-curvature areas, obstructed boundaries, and insufficiently covered regions. Therefore, it remains necessary to improve the targeting of PVD coating uniformity detection on complex curved surfaces and the reliability of thickness distribution reconstruction. Summary of the Invention

[0004] In view of this, this specification provides a method and system for detecting the uniformity of the thickness of a high-wear-resistant PVD coating layer in bathroom fixtures, in order to solve the above-mentioned problems.

[0005] This specification provides a method for detecting the uniformity of the thickness of a high wear-resistant PVD coating layer for bathroom fixtures, comprising: acquiring a three-dimensional model of the workpiece to be tested, dividing the surface of the three-dimensional model into multiple surface elements; and establishing multiple discrete postures of the workpiece during the coating process based on the spatial position of the PVD source, the installation posture of the workpiece, and the rotation information of the fixture. For each surface element under each discrete pose, determine the reachability state of the surface element relative to the PVD source to obtain the reachability state sequence of each surface element; determine the detection partition and partition boundary based on the difference between the reachability state sequences of adjacent surface elements. Based on the detection zone, the zone boundary, and the surface curvature, an eddy current thickness measurement scanning path is generated; the robot arm is controlled to drive the eddy current thickness measurement probe to scan the workpiece surface along the scanning path, and the measurement position coordinates and corresponding film thickness data are collected. The film thickness data is mapped to the corresponding surface element of the three-dimensional model. Film thickness interpolation is performed on the surface element that is not directly measured. The interpolation only uses the measured data that belongs to the same detection zone as the surface element to be interpolated. Based on the film thickness difference on both sides of the partition boundary, the film thickness change rate of adjacent measurement points within the partition, and the range of unmeasured areas, a supplementary scanning path is generated and a retest is performed; a three-dimensional thickness distribution is generated based on the supplemented full-surface film thickness data to identify areas with abnormal film thickness.

[0006] In some implementations, when determining the reachability of a surface element relative to the PVD source, the surface element is marked as reachable only if both of the following conditions are met simultaneously: The angle between the outward normal vector of the surface element in the current discrete pose and the direction from the centroid of the surface element to the PVD source is less than 90 degrees; and the ray emitted from the centroid of the surface element along the direction pointing to the PVD source does not intersect with other surface elements in the three-dimensional model; wherein, the intersection determination of the ray with other surface elements is achieved by performing ray-triangle intersection operation after establishing a hierarchical bounding box acceleration structure for the three-dimensional model.

[0007] In some implementations, determining the detection partition and partition boundary based on the difference between the reachable state sequences of adjacent surface elements includes: The cumulative reachability is calculated for each of the surface elements, where the cumulative reachability is the ratio of the number of reachable states of the surface element in all the discrete states to the total number of discrete states. For topologically adjacent face pairs, the proportion of the number of poses with inconsistent states in their reachable state sequences to the total number of discrete poses is calculated as the difference degree. The difference degree is compared with the partition difference threshold, which is the sum of the average difference degree of all adjacent facet pairs plus the sensitivity coefficient multiplied by the standard deviation of the difference degree. The sensitivity coefficient is obtained by comparing the partition boundary position with the position of the abrupt change in the measured film thickness on the same type of standard sample. When the difference degree is not less than the partition difference threshold, the common edge between the adjacent facet pairs is marked as the partition boundary.

[0008] In some implementations, determining the detection partition further includes: for the set of adjacent face elements not separated by the partition boundary, determining each connected component by breadth-first search, with each connected component constituting a detection partition; each partition boundary records the distribution information of the cumulative reachability difference of face elements on both sides of the boundary along the boundary.

[0009] In some implementations, when performing film thickness interpolation on surface elements that are not directly measured, an inverse distance weighted interpolation method is used. The inverse power of the geodesic distance along the triangular grid between the surface element to be interpolated and each measured surface element in the same detection zone is used as the weight to perform a weighted average of the film thickness values ​​of each measured surface element in the same detection zone, thereby obtaining the estimated film thickness value of the surface element to be interpolated.

[0010] In some implementations, when generating the eddy current thickness measurement scanning path based on the detection partition, the partition boundary, and the surface curvature, the scanning line spacing within each detection partition is determined according to the average curvature of the surface elements within that partition; the larger the average curvature, the smaller the line spacing. The scanning path is arranged in parallel lines along the direction of surface curvature change within the partition.

[0011] In some embodiments, generating the eddy current thickness measurement scanning path further includes generating additional scan lines parallel to the direction of the partition boundary on both sides of the partition boundary; the greater the difference between the reachable state sequences of adjacent surface elements on both sides of the partition boundary, the more additional scan lines are generated.

[0012] In some implementations, generating the supplementary scanning path based on the film thickness difference on both sides of the partition boundary includes: extracting the film thickness values ​​of the nearest row of measured surface cells on both sides of the partition boundary, calculating the average film thickness on both sides of the boundary respectively, and using the absolute value of the difference between the average film thicknesses on both sides as the film thickness difference; comparing the film thickness difference with a boundary thickness difference threshold, the boundary thickness difference threshold being determined based on the target film thickness and product uniformity specifications; and generating supplementary scanning lines on both sides of the partition boundary along a direction parallel to the boundary when the film thickness difference exceeds the boundary thickness difference threshold.

[0013] In some implementations, the supplementary scanning path is generated based on the film thickness change rate of adjacent measurement points within a partition, including: calculating the ratio of the absolute value of the difference in film thickness values ​​between adjacent measurement points within the same detection partition to the distance along the curved surface between the two points, as the film thickness change rate; comparing the film thickness change rate with a gradient threshold, which is obtained by calibrating the statistical distribution of film thickness change rates between adjacent points in a normal coating area on a standard sample; and when the film thickness change rate exceeds the gradient threshold, generating a denser supplementary scanning line along the gradient direction in the corresponding region.

[0014] This specification provides a high wear-resistant sanitary ware PVD coating thickness uniformity detection system, including: a model and posture establishment module, used to acquire a three-dimensional model of the workpiece to be tested, divide the surface of the three-dimensional model into multiple surface elements, and establish multiple discrete postures of the workpiece during the coating process based on the spatial position of the PVD source, the workpiece installation posture and the fixture rotation information. The detection partition determination module is used to determine the reachability state of each surface element relative to the PVD source under each discrete pose, obtain the reachability state sequence of each surface element, and determine the detection partition and partition boundary based on the difference between the reachability state sequences of adjacent surface elements. The scanning measurement module is used to generate an eddy current thickness measurement scanning path based on the detection zone, the zone boundary and the surface curvature, and control the robot to drive the eddy current thickness measurement probe to scan the workpiece surface along the scanning path, and collect the measurement position coordinates and corresponding film thickness data. The film thickness reconstruction module is used to map the film thickness data to the corresponding surface element of the three-dimensional model, and to perform film thickness interpolation on the surface element that is not directly measured. The interpolation only uses the measured data that belongs to the same detection zone as the surface element to be interpolated. The supplementary scanning and anomaly identification module is used to generate a supplementary scanning path and perform a retest based on the film thickness difference on both sides of the partition boundary, the film thickness change rate of adjacent measurement points within the partition, and the range of unmeasured areas. It also generates a three-dimensional thickness distribution based on the supplemented full-surface film thickness data and identifies film thickness anomaly areas.

[0015] In the various embodiments provided in this specification, the reachability of each surface element on the workpiece surface during the coating process is determined based on the spatial location of the PVD source, the workpiece mounting posture, and the fixture rotation information. The differences in the reachability sequence of adjacent surface elements are used to determine the detection zones and their boundaries, ensuring that the division of the detection area reflects the differences in deposition conditions caused by orientation changes and geometric occlusion on complex curved surfaces. An eddy current thickness measurement scanning path is generated based on the detection zones, zone boundaries, and surface curvature. Film thickness interpolation is limited to the same detection zone, preserving possible abrupt changes in film thickness near the zone boundaries under limited measurement data conditions, and reducing thickness distribution distortion caused by cross-region interpolation. Furthermore, a supplementary scanning path is generated based on the film thickness difference on both sides of the boundary, local film thickness changes within the zone, and the unmeasured area. This allows the actual measurement results to correct insufficient initial scan coverage, ultimately obtaining a more complete film thickness distribution corresponding to the spatial location of the workpiece surface, thereby improving the accuracy and reliability of detecting the uniformity of PVD coating thickness in complex curved bathroom fixtures. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the method for detecting the uniformity of the thickness of a high-wear-resistant sanitary ware PVD coating layer provided in the embodiments of this specification. Figure 2 A schematic diagram of a detection partition driven by a PVD source reachable state sequence provided for the embodiments of this specification; Figure 3 A schematic diagram illustrating the partition boundary determination process provided for the embodiments of this specification; Figure 4A schematic diagram of an eddy current thickness measurement scanning path based on detection partitions and surface curvature provided for the implementation of this specification; Figure 5 A schematic diagram of membrane thickness interpolation under detection zone constraints provided for the embodiments of this specification; Figure 6 A schematic diagram of a high wear-resistant sanitary ware PVD coating thickness uniformity detection system provided in the embodiments of this specification. Figure 7 This is a structural diagram of an electronic device according to one embodiment of this application. Detailed Implementation

[0017] To enable those skilled in the art to better understand the solutions described in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification.

[0018] This embodiment provides a method for detecting the uniformity of PVD coating thickness in high-wear-resistant bathroom fixtures, applicable to online inspection scenarios of bathroom products coated using physical vapor deposition (PVD) technology. The workpiece to be inspected is a bathroom hardware component with a complex curved surface structure, such as a faucet body, shower handle, or rotary handle. Its surface has geometric features such as grooves, steps, and arc-shaped transition areas. During the PVD coating process, different areas receive varying fluxes of deposited particles due to geometric obstruction and orientation differences. The inspection system includes an eddy current thickness gauge probe, a 6-DOF robot arm, a workpiece positioning fixture, and a data processing unit. After coating, the workpiece is positioned at the inspection station, and the eddy current thickness gauge probe mounted at the end of the robot arm performs scanning measurements along the workpiece surface.

[0019] This specification provides a method for detecting the uniformity of the thickness of a high-wear-resistant PVD coating layer in bathroom fixtures. Please refer to [link / reference]. Figure 1 , Figure 1 This is a flowchart illustrating a method for detecting the uniformity of PVD coating thickness in high-wear-resistant bathroom fixtures, as provided in this specification. This embodiment provides the operational steps shown in the flowchart, but based on conventional or non-inventive methods, more or fewer operational steps may be included. The order of steps listed in this embodiment is merely one possible execution order among many, and does not represent the only possible execution order. Specifically, as follows... Figure 1 As shown, the method for detecting the uniformity of the thickness of the high wear-resistant sanitary ware PVD coating layer may include the following steps.

[0020] Step S110: Obtain the 3D model and divide it into surface elements to establish multiple discrete poses for the coating process.

[0021] In some embodiments, a three-dimensional model of the workpiece to be inspected is acquired, derived from product CAD design files or actual measurement data from a 3D scanner. The surface of the three-dimensional model is discretized using triangular meshing, dividing the continuous curved surface into multiple triangular elements. The side length of each element can be configured, for example, 2 to 5 mm in flat regions, and reduced to, for example, 0.5 to 2 mm in transition regions with greater curvature. The lower limit of the element size should not be less than the effective sensing area diameter of the eddy current thickness gauge probe. Each element records its centroid three-dimensional coordinates, unit outward normal vector, and area.

[0022] Specifically, multiple discrete orientations are established based on the spatial position of the PVD source, the workpiece mounting posture, and the fixture rotation information. The coordinate position of the PVD source within the coating chamber is determined by the equipment installation parameters, and the workpiece is held by a rotating fixture and rotates uniformly around a fixed axis. A complete rotation cycle is divided into equal parts. Discrete angular positions For example, taking angles from 72 to 360 corresponds to angle steps of 1 to 5 degrees. For each discrete angle... Constructing a rotation around an axis of rotation The rotation matrix is ​​used to calculate the centroid coordinates and normal vectors of each surface element in the coating cavity coordinate system under this posture, thereby establishing multiple discrete postures of the workpiece during the coating process.

[0023] Step S120: Determining the reachability state of each surface element and identifying the detection partition and partition boundary. Specifically, for each surface element in each discrete pose, the reachability state of the surface element relative to the PVD source is determined to obtain the reachability state sequence of each surface element; based on the difference between the reachability state sequences of adjacent surface elements, the detection partition and partition boundary are determined.

[0024] Figure 2The figure illustrates a detection partition driven by a PVD source reachability state sequence, as provided in the embodiments of this specification. Based on the spatial location of the PVD source, the workpiece's 3D model, and fixture rotation information, multiple discrete postures of the workpiece during the coating process are established, including posture 1, posture 2, up to posture N, where N represents the total number of discrete postures. For example surface element p, reachability is determined for each discrete posture: a surface element is considered reachable if it faces the PVD source and is not obstructed by other surface elements; otherwise, it is considered unreachable, with 1 representing reachability and 0 representing unreachability, thus forming a reachability state sequence for surface element p. For surface element q, which is topologically adjacent to surface element p, its reachability state sequence is also obtained, and the proportion of postures with inconsistent states between the two surface elements to the total number of discrete postures is used as the difference degree. The difference degree is compared with a partition difference threshold. When the difference degree is not less than the partition difference threshold, the common edge between surface element p and surface element q is marked as the partition boundary. Adjacent surface elements not separated by partition boundaries are connected to form detection partitions A, B, and C as shown in the figure, separated by the partition boundaries.

[0025] Specifically, Figure 3 This is a schematic diagram of the partition boundary determination process provided in the embodiments of this specification. In step S210, the reachability state of the surface element relative to the PVD source is determined.

[0026] In some embodiments, the reachability state of each surface element relative to the PVD source is determined for each surface element under each discrete orientation, and it is marked as reachable when both the orientation condition and the occlusion condition are satisfied.

[0027] The orientation condition is determined by calculating the angle between the outward normal vector of the surface element in its current discrete attitude and the direction from the centroid of the surface element to the PVD source. The orientation condition is satisfied when this angle is less than 90 degrees. Specifically, let the surface element... In posture The unit external normal vector is The unit direction vector from the centroid of the surface element to the PVD source is: Calculate the dot product of the two: ; in It is a unit vector. For a unit vector, when The orientation condition is met, indicating that the surface element is oriented towards the PVD source. As an example, the normal vector of a certain surface element is... The unit direction pointing to the PVD source is The dot product is 0.97, which is greater than 0, so the orientation condition is met.

[0028] In one possible implementation, the occlusion condition is determined by emitting a ray from the centroid of the face element along the direction pointing to the PVD source, and checking whether the ray intersects with other face elements in the 3D model; if they do not intersect, the occlusion condition is satisfied. The ray-triangle intersection operation can be performed using the Möller-Trumbore algorithm, which calculates the ray parameters by simultaneously solving the ray parameter equations and the triangle centroid coordinate equations. and barycentric coordinates ,when , , and The ray intersects the triangle. To improve the efficiency of determining a large number of face elements, a hierarchical bounding box (BVH) acceleration structure is pre-established for the 3D model, reducing the complexity of ray traversal from linear to logarithmic. BVH recursively divides the set of face elements into two subsets according to the spatial midplane. Each subset is wrapped by an axis-aligned bounding box. During ray traversal, it first checks whether it intersects with the bounding box before delving into the child nodes, thus skipping a large number of irrelevant face elements.

[0029] If both conditions are met, the reachability state of the surface element in the current discrete attitude is assigned a value of 1; otherwise, it is assigned a value of 0. For each surface element, all... After a discrete pose, the reachable state sequence of the surface element is obtained.

[0030] In step S220, the cumulative reachability is calculated and the difference between adjacent facets is calculated.

[0031] In some embodiments, the cumulative reachability is calculated based on the reachability sequence of each surface element, which is the ratio of the number of reachable states of that surface element to the total number of discrete attitudes: ; in For face element The cumulative reachability, with a value ranging from 0 to 1; For face element In posture The reachable state value (0 or 1); The total number of discrete attitudes. This reflects the relative proportion of time a surface element receives deposited particles during the coating rotation process, and is positively correlated with the film thickness at that location. For example, if... And if a certain surface element has 180 poses that are reachable, then .

[0032] In one embodiment, for topologically adjacent face pairs in a triangular mesh (i.e., two face pairs sharing an edge), the proportion of poses with inconsistent states in their reachable state sequences to the total number of discrete poses is calculated as the dissimilarity level: ; in For face element With face element The degree of difference between them, with a value ranging from 0 to 1; and The two elements are in attitude. The reachable state value. This indicates that the reachable states of the two facet elements are completely identical in all orientations. A larger value indicates a greater difference in the timing patterns of the two facet elements being shaded or their orientation changing, and a greater likelihood of a step change in the coating thickness at the boundary.

[0033] Since the PVD film thickness is directly proportional to the time integral of the particle flux received by each surface element during the coating process, and the reachable state sequence directly determines this integral value, the degree of difference in the reachable state sequence is... It is positively correlated with the cumulative film thickness difference between the two facets. When A value significantly higher than the average level of the entire neighborhood indicates a sudden change in deposition conditions, which most likely corresponds to a step change in actual film thickness. As a threshold, it can statistically distinguish between gradually varying boundaries caused by normal curvature changes and abrupt boundaries caused by occlusion.

[0034] In step S230, the partition difference threshold is determined and the detection partition is generated.

[0035] In some embodiments, the difference degree of each adjacent facet pair is compared with a partition difference threshold. If the difference degree is not less than the partition difference threshold, the common edge between the adjacent facet pairs is marked as the partition boundary. The partition difference threshold is determined by statistically analyzing the difference degree values ​​of all adjacent facet pairs of the workpiece and calculating the average difference degree. and standard deviation of variability The partition difference threshold is the sum of the mean difference, the sensitivity coefficient, and the standard deviation of the difference.

[0036] in This is the threshold for partition differences; This is the arithmetic mean of the differences between all adjacent facet pairs; The standard deviation of the variance; This is the sensitivity coefficient, with a value ranging from, for example, 0.5 to 2.0.

[0037] Optionally, sensitivity coefficient The location of the partition boundary on a standard sample of the same type is determined by comparing it with the location of the abrupt change in film thickness measured in the cross-section. The standard sample is the same material and coating process as the workpiece to be tested, and at least three samples are selected. For each sample, at least five measurement sections are taken along a typical cross-section (including features such as grooves and steps), and the location of the film thickness abrupt change is measured using a metallographic microscope. Several samples are selected... Candidate values ​​(e.g., 0.5, 0.8, 1.0, 1.2, 1.5, 2.0) are used to calculate partition boundaries. The partition boundary corresponding to each candidate value is then compared one by one with the film thickness step positions of all cross-sections of the standard sample. The root mean square of the boundary position deviation is calculated, and the value that minimizes this deviation is selected. Value. In one example, after calibrating a certain faucet component. Take 1.2.

[0038] In one possible implementation, for a set of adjacent facets not separated by partition boundaries, a breadth-first search is used to determine each connected component, and each connected component constitutes a detection partition. Specifically, starting from any unlabeled facet, it is added to a queue. Then, facets are removed from the queue, and their topologically adjacent facets are traversed. If adjacent facets are unlabeled and their common edge is not marked as a partition boundary, then the adjacent facets are added to the queue and marked as belonging to the same partition; this process is repeated until the queue is empty. All unlabeled facets are traversed until all facets are assigned to a detection partition.

[0039] Specifically, the boundary record for each partition records the distribution information of the cumulative reachability difference between the two lateral face elements along the boundary. That is, for each common edge on the boundary, the absolute value of the cumulative reachability difference between its two lateral face elements is recorded. This information is used for measurement encryption near the boundary in subsequent scanning paths.

[0040] In step S130, the eddy current thickness measurement scanning path is generated and the film thickness data is acquired. Specifically, based on the detection zone, the zone boundary, and the surface curvature, the eddy current thickness measurement scanning path is generated; the robot arm is controlled to drive the eddy current thickness measurement probe to scan the workpiece surface along the scanning path, and the measurement position coordinates and corresponding film thickness data are acquired.

[0041] Figure 4The schematic diagram of the eddy current thickness measurement scanning path based on detection zones and surface curvature provided in this specification is shown in the figure. The surface of the workpiece to be inspected is divided into zones A, B, and C according to the detection zones and their boundaries. The red solid lines represent the zone boundaries. Within each detection zone, an eddy current thickness measurement scanning path is set according to the average surface curvature. The blue solid lines represent the scanning path and its scanning direction. Larger line spacing is used in areas with smaller average curvature, and smaller line spacing is used in areas with larger average curvature, so that the scanning density adapts to the geometric changes of the workpiece surface. Additional scanning lines are arranged along the zone boundaries on both sides, indicated by green dashed lines in the figure, to increase the measurement density near the boundaries. An eddy current thickness measurement probe is mounted at the end of a robotic arm. The robotic arm drives the eddy current thickness measurement probe along the generated scanning path to scan and measure the workpiece surface in zones A, B, and C, and collect film thickness data at the corresponding locations.

[0042] In some embodiments, an eddy current thickness measurement scanning path is generated based on the detection zones, zone boundaries, and surface curvature. The line spacing within each detection zone is determined based on the average curvature of the surface elements within that zone; the greater the average curvature, the smaller the line spacing. ; in This is the actual line spacing, in mm; The baseline row spacing is in mm, for example, 3 to 8 mm, and should not exceed 4 times the effective sensing diameter of the probe. This represents the absolute value of the average curvature of the surface elements in this region, in mm. ; Reference curvature, unit mm For example, take 0.05 to 0.2 mm. The interpolation reconstruction error was determined by comparing different row spacings on a known curved surface sample. Specifically, the row spacing was gradually increased, and the relationship between the row spacing and curvature was observed when the interpolation error reached 3% of the target film thickness. This process was then used to infer the relationship between the row spacing and curvature. Values.

[0043] In one embodiment, the scan path is generated using parallel lines, arranged along the principal curvature direction of the inner surface of the partition. Additional scan lines parallel to the partition boundary are generated on both sides of the partition boundary, with the spacing between the additional scan lines and the boundary being the line spacing. For example, 0.3 times. The greater the difference between the reachable state sequences of adjacent surface elements on both sides of the partition boundary, the more additional scan lines are added; for example, when the difference is below 0.3, there is 1 additional line on each side, and when the difference exceeds 0.3, the number of additional lines on each side increases to 3. Scan line segments within each partition are connected into a continuous trajectory according to the principle of spatial proximity. When crossing partitions, a probe lifting segment is inserted to prevent collisions. Each path point includes position coordinates and probe orientation. The probe axis direction is aligned with the normal direction of the workpiece surface, with a deviation not exceeding, for example, 5 degrees.

[0044] Specifically, the robot arm is controlled to drive the eddy current thickness gauge probe to scan the workpiece surface along the scanning path, collecting the measurement position coordinates and corresponding film thickness data. The sampling interval can be configured, for example, from 0.5 to 2 mm. The three-dimensional coordinates of the measurement point are calculated by combining the robot arm end pose with the probe installation calibration parameters, and stored in correspondence with the film thickness measurement value.

[0045] In step S140, the film thickness data is mapped to film thickness interpolation within the same detection zone. Specifically, the film thickness data is mapped to the corresponding surface elements of the three-dimensional model, and film thickness interpolation is performed on surface elements that are not directly measured. The interpolation only uses measured data belonging to the same detection zone as the surface element to be interpolated.

[0046] In some embodiments, film thickness data is mapped to corresponding facets of the 3D model. That is, for each measurement point, the nearest facet on the model surface whose projection falls within its 3D coordinates is found, and the measurement point is associated with that facet. When the same facet contains multiple measurement points, the median of all film thickness values ​​is taken as the representative value.

[0047] In this process, film thickness interpolation is performed on surface elements that are not directly measured. The interpolation only uses measured data from the same detection zone as the surface element to be interpolated. During PVD coating, the zone boundary corresponds to the transition position on the workpiece surface from visible to obscured. The cumulative amount of deposited particles received by the surface elements on both sides of the boundary may show a step difference. If interpolation is performed across zones, the film thickness value of the thicker side will be transferred to the thinner side, smoothing out the actual thickness step and making it disappear in the detection results. By limiting the interpolation range to within the same detection zone, the film thickness distribution of each zone is reconstructed independently, preserving the thickness abrupt change information at the boundary.

[0048] Figure 5 This diagram illustrates film thickness interpolation under detection zone constraints, as provided in the embodiments of this specification. The workpiece surface is divided into detection zone A and detection zone B by zone boundaries, with red solid lines representing the zone boundaries. Blue dots represent measured surface elements, and orange dots represent surface elements to be interpolated. For any surface element to be interpolated, only measured surface elements belonging to the same detection zone are selected for film thickness interpolation. The green line represents the geodesic distance between the surface element to be interpolated and the measured surface elements within the same detection zone, determined along a triangular mesh, and the interpolation weight is calculated accordingly. Measured surface elements located on the other side of the zone boundary do not participate in the interpolation of the current surface element to be interpolated. In the diagram, gray dashed lines and crosses crossing the zone boundaries indicate "not participating in interpolation," thus achieving interpolation without crossing zones. By performing interpolation within the same detection zone in both detection zone A and detection zone B, the mutual transfer of film thickness data on both sides of the boundary can be avoided, smoothing out actual film thickness abrupt changes.

[0049] Specifically, an inverse distance weighted interpolation method is used, with the inverse power of the geodesic distance along the triangular grid between the surface element to be interpolated and each measured surface element within the same detection zone as the weight. The film thickness values ​​of each measured surface element within the same detection zone are then weighted and averaged to obtain the estimated film thickness value of the surface element to be interpolated. ; in For the interpolation element The estimated film thickness, in units m; Measured surface elements within the same detection zone The film thickness value, in units m; For face element With face element The geodesic distance between them along the triangular mesh, in mm, is calculated by Dijkstra's shortest path algorithm, which accumulates the edge lengths on the mesh edges. Specifically, this algorithm uses face cells as nodes and the shared edge length between adjacent face cells as edge weights, gradually relaxing the distance estimation of each node from the starting face cell until convergence. This is the distance decay exponent, with a value ranging from 1 to 3, for example, 2; For face element The set of all measured surface elements within the detection zone.

[0050] As an example, suppose there are three measured surfaces within the same detection zone surrounding an unmeasured surface, with geodetic distances of 2mm, 4mm, and 6mm, and film thicknesses of 1.8mm and 1.8mm respectively. m, 2.0 m, 2.2 m, take The weights are respectively , , The weighted average yielded an estimated film thickness of approximately 1.86. m.

[0051] In step S150, a supplementary scanning path is generated and a retest is performed based on the difference in film thickness on both sides of the partition boundary, the film thickness change rate of adjacent measurement points within the partition, and the range of unmeasured areas.

[0052] In some embodiments, for each partition boundary, the film thickness values ​​of the nearest row of measured surface cells on both sides of the boundary are extracted, and the average film thickness on both sides of the boundary is calculated respectively. and The absolute value of the difference between the average film thicknesses on both sides is taken as the film thickness difference value: ; in The difference in film thickness across the boundary of the partition is expressed in units. m; , These are the arithmetic mean of the measured cell film thicknesses near the boundary in zones A and B on both sides of the boundary, respectively, in units of... m.

[0053] Specifically, the film thickness difference is compared with the boundary thickness difference threshold. The comparison is made whereby the boundary thickness difference threshold is determined based on the target film thickness and the product uniformity specification. For example, let the target film thickness of the product be... The product specifications require that the film thickness uniformity deviation does not exceed [a certain value]. For example, 10% to 15%, then Pick For example, the absolute value corresponding to 5% to 8%. In one example, if the target film thickness... If m is taken as a proportion of 6%, then m. When the film thickness difference exceeds the boundary thickness difference threshold, supplementary scan lines are generated on both sides of the boundary of the segment along a direction parallel to the boundary. The line spacing is, for example, 0.3 times the normal row spacing, and 2 to 3 lines are generated on each side of the boundary.

[0054] In one possible implementation, for adjacent measurement points within the same detection zone, the ratio of the absolute value of the difference in film thickness between adjacent measurement points to the distance between the two points along the curved surface is calculated as the film thickness change rate. ; in For adjacent measurement points and The rate of change of film thickness between, in units m / mm; , The film thickness values ​​at two measurement points, in units of... m; The distance between two points along the curved surface is expressed in mm.

[0055] In one embodiment, the film thickness change rate is compared with a gradient threshold. A comparison is made. Among them, the gradient threshold... The thickness variation rate between adjacent points in a normally coated area on a standard sample was measured and calibrated using statistical distribution. The standard sample was a flat plate of the same material as the workpiece under test, coated to the target thickness using the same PVD process, and with an unobstructed surface. At least 200 pairs of adjacent points were measured on the sample surface at the same sampling interval (consistent with the initial scan interval). The thickness variation rate for each pair was calculated, and its distribution was statistically analyzed. Twice the 95th percentile of this distribution was taken as the standard thickness variation rate. .

[0056] In one example Take 0.2 m / mm. When the film thickness change rate exceeds the gradient threshold, a denser supplementary scan line is generated along the gradient direction in the corresponding region, increasing the local measurement density to 2 to 3 times the original density.

[0057] In one embodiment, connected regions formed by facets not covered by measurement data within each detection zone are statistically analyzed. When the area of ​​this connected region exceeds an area ratio threshold relative to the total area of ​​the detection zone, or when the geodesic distance from any facet within this connected region to the nearest measured facet exceeds a distance threshold, a coverage scan path is generated for that connected region. The area ratio threshold is, for example, 20% to 30%, and the distance threshold is, for example, the row spacing. Two to three times that.

[0058] The determination of the area ratio threshold and distance threshold is based on the following: On simulated data with known film thickness distribution, the unmeasured area is gradually expanded, and the area ratio and maximum geodesic distance corresponding to the interpolation error exceeding the allowable value (e.g., 3% of the target film thickness) are observed. This critical value is then used as the threshold. For the unmeasured connected areas to be covered, parallel line scanning paths are generated according to the row spacing determined by the corresponding surface curvature.

[0059] In one embodiment, the robotic arm performs a retest along the generated supplementary scanning path, and the newly acquired film thickness data is assigned to the corresponding detection zone according to the surface area. When there is duplicate data in the same surface area between the initial measurement and the supplementary measurement, the median of the two measurements is taken as the representative film thickness value for that surface area. The supplemented full-surface film thickness data is then used to perform inverse distance weighted interpolation within the same detection zone for all surface areas that were not directly measured.

[0060] In some embodiments, a three-dimensional thickness distribution is generated based on the supplemented full-surface film thickness data, and the film thickness values ​​of each surface element are displayed on the three-dimensional model in a color mapping manner.

[0061] The method for identifying regions with abnormal film thickness is to calculate the global mean and global standard deviation of the film thickness values ​​of all surface elements by weighting them by area. ; in This is the area-weighted global mean, in units of... m; The area-weighted global standard deviation, in units m; For face element Area, in mm ; For face element The film thickness value (measured or interpolated), in units m; This represents the total number of face elements.

[0062] In one embodiment, connected regions with film thickness values ​​lower than the global mean minus the determination coefficient multiplied by the global standard deviation are marked as excessively thin regions, and connected regions with film thickness values ​​higher than the global mean plus the determination coefficient multiplied by the global standard deviation are marked as excessively thick regions. Determination coefficient The value range is, for example, 2 to 3, determined according to the product quality qualification standard. By statistically analyzing the film thickness distribution of qualified products in historical batches, the value is selected to ensure that the false judgment rate (judging qualified products as abnormal) is lower than the allowable value of the product quality specification. Values.

[0063] In one example, if the required false positive rate is less than 5% and the film thickness is approximately normally distributed, then take... Approximately 4.6% of the area falls into the abnormal range. For all identified excessively thin and excessively thick regions, the system outputs their location range, area, and extreme film thickness on the 3D model, generating a detection report.

[0064] This method establishes detection zones based on PVD source reachability analysis, ensuring that the zone boundaries correspond to abrupt changes in film thickness caused by geometric occlusion during the coating process. This restricts cross-zone data participation in subsequent interpolation and reconstruction, preventing the smoothing of true film thickness abrupt changes at the boundaries. Simultaneously, it adaptively generates supplementary scanning paths based on three conditions: film thickness difference across zone boundaries, local gradient anomalies within zones, and unmeasured areas. This allows for more intensive re-measurement of complex curved surface occlusion areas and areas with abrupt film thickness changes, reducing missed detections.

[0065] This specification provides a system for detecting the uniformity of PVD coating thickness in high-wear-resistant bathroom fixtures. Please refer to [link / reference]. Figure 6 The system may include: The model and attitude establishment module 601 is used to acquire a three-dimensional model of the workpiece to be inspected, divide the surface of the three-dimensional model into multiple surface elements, and establish multiple discrete attitudes of the workpiece during the coating process based on the spatial position of the PVD source, the installation attitude of the workpiece, and the rotation information of the fixture. The detection partition determination module 602 is used to determine the reachability state of each surface element relative to the PVD source under each discrete posture, obtain the reachability state sequence of each surface element, and determine the detection partition and partition boundary based on the difference between the reachability state sequences of adjacent surface elements. The scanning measurement module 603 is used to generate an eddy current thickness measurement scanning path based on the detection zone, the zone boundary and the surface curvature, and control the robot arm to drive the eddy current thickness measurement probe to scan the workpiece surface along the scanning path, and collect the measurement position coordinates and corresponding film thickness data. The film thickness reconstruction module 604 is used to map the film thickness data to the corresponding surface element of the three-dimensional model, and to perform film thickness interpolation on the surface element that is not directly measured. The interpolation only uses the measured data that belongs to the same detection zone as the surface element to be interpolated. The supplementary scanning and anomaly identification module 605 is used to generate a supplementary scanning path and perform a retest based on the film thickness difference on both sides of the partition boundary, the film thickness change rate of adjacent measurement points within the partition, and the range of unmeasured areas. It also generates a three-dimensional thickness distribution based on the supplemented full-surface film thickness data and identifies film thickness anomaly areas.

[0066] For details regarding the specific functions and effects of this system, please refer to other implementation methods in this manual for comparison and explanation; further details will not be provided here. Each module in this system can be implemented entirely or partially through software, hardware, or a combination thereof. Each module can be embedded in or independent of the processor in the computer device in hardware form, or it can be stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0067] This specification also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a computer, implements the process formulation adjustment method in any of the above embodiments.

[0068] This specification also provides a computer program product containing instructions that, when executed by a computer, cause the computer to implement the process formula adjustment method in any of the above embodiments.

[0069] This specification also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, which, when executed by the processor, implements the process formula adjustment method in any of the above embodiments.

[0070] In some implementations, please refer to Figure 7 The computer device can be a terminal, and its internal structure diagram can be as follows: Figure 7 As shown, the computer device includes a processor, memory, and a communication interface connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage medium. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a process formulation adjustment method.

[0071] It is understood that the specific examples in this document are only intended to help those skilled in the art better understand the embodiments described herein, and are not intended to limit the scope of the invention.

[0072] It is understood that in the various embodiments described in this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments described in this specification.

[0073] It is understood that the various implementation methods described in this specification can be implemented individually or in combination, and the implementation methods in this specification are not limited in this respect.

[0074] Unless otherwise stated, all technical and scientific terms used in the embodiments of this specification have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this specification. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this specification are also intended to include the plural forms unless the context clearly indicates otherwise.

[0075] It is understood that the processor in the embodiments of this specification can be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method embodiments can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this specification. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this specification can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above methods.

[0076] It is understood that the memory in the embodiments of this specification may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may be random access memory (RAM). It should be noted that the memory in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0077] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this specification.

[0078] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the aforementioned method implementations, and will not be repeated here.

[0079] The above description is merely a specific embodiment of this specification, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this specification should be included within the scope of protection of this specification.

Claims

1. A method for detecting the uniformity of thickness of a high-wear-resistant sanitary ware PVD coating layer, characterized in that, include: A three-dimensional model of the workpiece to be inspected is obtained, and the surface of the three-dimensional model is divided into multiple surface elements. Based on the spatial position of the PVD source, the installation posture of the workpiece, and the rotation information of the fixture, multiple discrete postures of the workpiece during the coating process are established. For each surface element under each discrete pose, determine the reachability state of the surface element relative to the PVD source to obtain the reachability state sequence of each surface element; determine the detection partition and partition boundary based on the difference between the reachability state sequences of adjacent surface elements. Based on the detection zone, the zone boundary, and the surface curvature, an eddy current thickness measurement scanning path is generated; the robot arm is controlled to drive the eddy current thickness measurement probe to scan the workpiece surface along the scanning path, and the measurement position coordinates and corresponding film thickness data are collected. The film thickness data is mapped to the corresponding surface element of the three-dimensional model. Film thickness interpolation is performed on the surface element that is not directly measured. The interpolation only uses the measured data that belongs to the same detection zone as the surface element to be interpolated. Based on the film thickness difference on both sides of the partition boundary, the film thickness change rate of adjacent measurement points within the partition, and the range of unmeasured areas, a supplementary scanning path is generated and a retest is performed; a three-dimensional thickness distribution is generated based on the supplemented full-surface film thickness data to identify areas with abnormal film thickness.

2. The method according to claim 1, characterized in that, When determining the reachability state of a surface element relative to the PVD source, the surface element is marked as reachable only if both of the following conditions are met simultaneously: The angle between the outward normal vector of the surface element in the current discrete pose and the direction from the centroid of the surface element to the PVD source is less than 90 degrees; and the ray emitted from the centroid of the surface element along the direction pointing to the PVD source does not intersect with other surface elements in the three-dimensional model; wherein, the intersection determination of the ray with other surface elements is achieved by performing ray-triangle intersection operation after establishing a hierarchical bounding box acceleration structure for the three-dimensional model.

3. The method according to claim 2, characterized in that, The step of determining the detection partition and partition boundary based on the difference between the reachable state sequences of adjacent surface elements includes: The cumulative reachability is calculated for each of the surface elements, where the cumulative reachability is the ratio of the number of reachable states of the surface element in all the discrete states to the total number of discrete states. For topologically adjacent face pairs, the proportion of the number of poses with inconsistent states in their reachable state sequences to the total number of discrete poses is calculated as the difference degree. The difference degree is compared with the partition difference threshold, which is the sum of the average difference degree of all adjacent facet pairs plus the sensitivity coefficient multiplied by the standard deviation of the difference degree. The sensitivity coefficient is obtained by comparing the partition boundary position with the position of the abrupt change in the measured film thickness on the same type of standard sample. When the difference degree is not less than the partition difference threshold, the common edge between the adjacent facet pairs is marked as the partition boundary.

4. The method according to claim 3, characterized in that, The determination of the detection partition further includes: for the set of adjacent face elements not separated by the partition boundary, determining each connected component by breadth-first search, and each connected component constitutes a detection partition; each partition boundary records the distribution information of the cumulative reachability difference of face elements on both sides of the boundary along the boundary.

5. The method according to claim 1, characterized in that, When performing film thickness interpolation on surface elements that are not directly measured, an inverse distance weighted interpolation method is adopted. The inverse power of the geodesic distance along the triangular grid between the surface element to be interpolated and each measured surface element in the same detection zone is used as the weight to perform a weighted average of the film thickness values ​​of each measured surface element in the same detection zone, so as to obtain the estimated film thickness value of the surface element to be interpolated.

6. The method according to claim 1, characterized in that, When generating the eddy current thickness measurement scanning path based on the detection zone, the zone boundary, and the surface curvature, the scanning line spacing within each detection zone is determined according to the average curvature of the surface elements within that zone. The larger the average curvature, the smaller the line spacing. The scanning path is arranged in parallel lines along the direction of surface curvature change within the zone.

7. The method according to claim 1, characterized in that, The generation of the eddy current thickness measurement scanning path further includes: generating additional scan lines parallel to the direction of the partition boundary on both sides of the partition boundary; the greater the difference between the reachable state sequences of adjacent surface elements on both sides of the partition boundary, the more additional scan lines there are.

8. The method according to claim 1, characterized in that, The supplementary scanning path is generated based on the difference in film thickness on both sides of the partition boundary, including: Extract the film thickness values ​​of the nearest row of measured surface cells on both sides of the partition boundary, calculate the average film thickness on both sides of the boundary, and take the absolute value of the difference between the average film thicknesses on both sides as the film thickness difference value; compare the film thickness difference value with the boundary thickness difference threshold, which is determined according to the target film thickness and product uniformity specifications; when the film thickness difference value exceeds the boundary thickness difference threshold, generate supplementary scan lines on both sides of the partition boundary along the direction parallel to the boundary.

9. The method according to claim 8, characterized in that, The supplementary scanning path is generated based on the film thickness change rate of adjacent measurement points within the partition, including: calculating the ratio of the absolute value of the difference in film thickness values ​​between adjacent measurement points within the same detection partition to the distance along the curved surface between the two points, as the film thickness change rate; comparing the film thickness change rate with a gradient threshold, which is obtained by calibrating the statistical distribution of film thickness change rates between adjacent points in a normal coating area on a standard sample; when the film thickness change rate exceeds the gradient threshold, generating a denser supplementary scanning line along the gradient direction in the corresponding region.

10. A system for detecting the uniformity of PVD coating thickness in high-wear-resistant bathroom fixtures, characterized in that, include: The model and attitude establishment module is used to acquire a three-dimensional model of the workpiece to be inspected, divide the surface of the three-dimensional model into multiple surface elements, and establish multiple discrete attitudes of the workpiece during the coating process based on the spatial position of the PVD source, the workpiece mounting attitude, and the fixture rotation information. The detection partition determination module is used to determine the reachability state of each surface element relative to the PVD source under each discrete pose, obtain the reachability state sequence of each surface element, and determine the detection partition and partition boundary based on the difference between the reachability state sequences of adjacent surface elements. The scanning measurement module is used to generate an eddy current thickness measurement scanning path based on the detection zone, the zone boundary and the surface curvature, and control the robot to drive the eddy current thickness measurement probe to scan the workpiece surface along the scanning path, and collect the measurement position coordinates and corresponding film thickness data. The film thickness reconstruction module is used to map the film thickness data to the corresponding surface element of the three-dimensional model, and to perform film thickness interpolation on the surface element that is not directly measured. The interpolation only uses the measured data that belongs to the same detection zone as the surface element to be interpolated. The supplementary scanning and anomaly identification module is used to generate a supplementary scanning path and perform a retest based on the film thickness difference on both sides of the partition boundary, the film thickness change rate of adjacent measurement points within the partition, and the range of unmeasured areas. It also generates a three-dimensional thickness distribution based on the supplemented full-surface film thickness data and identifies film thickness anomaly areas.

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