Control method for online monitoring and self-correction of spraying quality of automobile plastic part

Abstract

The invention provides a control method for online monitoring and self-correction of the spraying quality of an automobile plastic part, and relates to the technical field of automobile part machining. Comprising the following steps that according to to-be-sprayed information of a to-be-sprayed workpiece, the theoretical clamping groove position of an adaptive column is obtained; judging whether the actual surface has a target section which is not matched with the theoretical cambered surface or not; if yes, a first correction sequence corresponding to each target section is obtained, and the first correction sequence comprises a plurality of horizontal displacement point positions passed by the nozzle in the horizontal movement process in the target section and a first displacement deviation value corresponding to each horizontal displacement point position; and after the adaptive column is clamped into the theoretical clamping groove position, the spray head is controlled to conduct spraying operation along the horizontal moving path, and the corresponding first correction sequence is executed in each target section, so that a preset constant distance is kept between the spray head and the actual surface of the to-be-sprayed area all the time. The surface deviation can be recognized on line, the spraying track can be automatically corrected, and the adaptive bottleneck of a pure mechanical structure to part of special workpieces is broken through.

Description

Technical Field

[0001] The present application relates to the technical field of automobile parts processing, and in particular to a control method for online monitoring and self-correction of the spraying quality of automobile plastic parts. Background Art

[0002] In the field of automotive plastic trim spraying, the existing technology usually adopts a fixed-path translation spraying device. However, for workpieces with arched surfaces (such as rearview mirror bezels), this device will cause uneven spraying due to inconsistent distances between the nozzle and the workpiece surface, affecting the oxidation resistance and aesthetics. Therefore, a patent with application number 202321954968.9 was proposed to achieve the function of synchronizing the distance between the nozzle and various parts of the workpiece surface. A power component is provided to drive the moving component and the nozzle to move horizontally, and the bending degree of the adapter arc plate is adjusted by moving the adapter column in the slot to ensure that it is the same as the sprayed workpiece. The spring is used to apply pressure upward to the telescopic column and roller, so that the adapter arc plate with the same bending degree as the workpiece surface squeezes and limits the roller, driving the connecting column and the nozzle to move up and down synchronously to ensure that the distance between the nozzle and various parts of the workpiece is the same, thereby making the workpiece spray more uniform.

[0003] However, there are key problems in the use of this device: factors such as wear and tear of the injection mold after long-term use and differences in shrinkage rates of material batches will lead to local curvature deviations (local depressions) on the surface to be sprayed of the same model of workpiece. This causes a structural mismatch between the theoretical curved surface of the original adaptive arc plate and the actual surface, resulting in poor adaptability of the device for spraying. The spraying uniformity in the deviated depression area is inconsistent with that in the normal area, affecting the spraying quality of the plastic parts. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, the present application aims to provide a control method for online monitoring and self-correction of the spraying quality of automotive plastic parts. The method is based on a spraying device for automotive plastic trims, which includes a spray box, an adapter component, a moving component, and a spray head. The adapter component matches the workpiece surface by adapting the curvature of the arc plate. The moving component drives the spray head to rise and fall synchronously with the adapting arc plate through a spring and a telescopic column, so as to realize online identification of surface deviations and autonomous correction of the spraying trajectory, thereby breaking through the adaptability bottleneck of a purely mechanical structure. The control method comprises the following steps: According to the information of the workpiece to be sprayed, the theoretical slot position of the adapter column is obtained; the information to be sprayed includes the type of workpiece and the area to be sprayed; the theoretical slot position corresponds to the theoretical arc surface of the adapter arc plate; Determining whether there is a target section on the actual surface, the target section being a section on the actual surface that does not match the theoretical cambered surface; the actual surface being the surface of the area to be sprayed of the workpiece to be sprayed; If yes, then obtaining a first correction sequence corresponding to the target segment, the first correction sequence including a plurality of horizontal displacement points passed by the nozzle during horizontal movement within the target segment, and a first displacement deviation corresponding to each of the horizontal displacement points; After the adapter column is inserted into the theoretical slot position, the nozzle is controlled to perform the spraying operation along the horizontal movement path, and the corresponding first correction sequence is executed within the target section so that the nozzle always maintains a preset constant distance from the actual surface of the area to be sprayed.

[0005] According to the technical solution provided by the present application, determining whether the actual surface has a target section that does not match the theoretical cambered surface includes the following steps: Scanning along a horizontal moving path of the area to be sprayed to obtain a first curvature data set of the actual surface; Using the theoretical arc surface as a reference surface, discretizing the first curvature data set to divide it into a plurality of detection sections; The first deviation value between the actual curvature radius and the theoretical curvature radius in each of the detection segments is calculated. If the first deviation value corresponding to at least one of the detection segments is greater than a preset curvature tolerance threshold, it is determined that there is a target segment on the actual surface that does not match the theoretical curved surface.

[0006] According to the technical solution provided by the present application, after calculating the first deviation value between the actual curvature radius and the theoretical curvature radius in each detection section, the following steps are also included: The detection section where the first deviation value is greater than a preset curvature tolerance threshold is regarded as a primary abnormal section; Performing curvature continuity analysis on adjacent primary abnormal sections and calculating the curvature change rate between adjacent detection points; If the curvature change rate is greater than the first change rate, it is determined that a curvature mutation boundary exists; According to the spatial distribution characteristics of the curvature mutation boundary, more than N consecutive primary abnormal sections with the same-direction curvature deviation are merged into the same target section.

[0007] According to the technical solution provided by the present application, after the adapter column is clamped into the theoretical clamping slot position, before the nozzle is controlled to move along the horizontal path to perform the spraying operation, the following steps are also included: Controlling the no-load horizontal movement of the print head to obtain a calibration arc curve of the path traveled by the print head; wherein, during the no-load horizontal movement of the print head, the corresponding first correction sequence is not executed and the print head does not spray paint liquid; judging whether the theoretical slot position is credible according to the calibration arc curve and the theoretical arc curve corresponding to the theoretical arc surface; The control of the nozzle to perform spraying operation along the horizontal movement path includes the following steps: If so, the nozzle is controlled to perform spraying operation along the horizontal moving path.

[0008] According to the technical solution provided in this application, if the actual surface has a target section that does not match the theoretical curved surface, the following steps are also included: determining a position range of the target section on the horizontal moving path; Determine whether the position range is mapped to the two end areas of the adaptive arc plate, where the two end areas of the adaptive arc plate are the ranges along the length direction thereof that are greater than a preset distance threshold from the center point; The obtaining of the first correction sequence corresponding to the target segment comprises the following steps: If not, a first correction sequence corresponding to the target segment is obtained.

[0009] According to the technical solution provided by the present application, after determining whether the position range is mapped to the two end areas of the adaptive arc plate, the following steps are further included: Acquire all first displacement deviations in the first correction sequence corresponding to the target segment; Determining whether each of the first displacement deviations exceeds a safety displacement threshold, the safety displacement threshold being the maximum allowable compensation displacement of the spring while ensuring reliability and preventing plastic deformation; The step of executing the corresponding first correction sequence in the target segment comprises the following steps: If all the first displacement deviations do not exceed the safety displacement threshold, the corresponding first correction sequence is executed in the target section.

[0010] According to the technical solution provided by the present application, after determining whether each of the first displacement deviations exceeds a preset safety displacement threshold, the following steps are further included: If at least one of the first displacement deviations exceeds the safety displacement threshold, the horizontal displacement point corresponding to the first displacement deviation exceeding the safety displacement threshold is marked as a displacement point to be corrected; Correcting the first displacement deviations corresponding to all the displacement points to be corrected in the first correction sequence to the safety displacement threshold to obtain a second correction sequence corresponding to the target section; After the adapter column is locked into the theoretical slot position, the nozzle is controlled to perform a spraying operation along a horizontal movement path, and the corresponding second correction sequence is executed in the target section.

[0011] According to the technical solution provided by the present application, executing the corresponding first correction sequence in the target segment includes the following steps: A linear actuator installed on the side wall of the accommodating column is controlled to perform a corresponding displacement of the first displacement deviation when the spray head moves to each of the horizontal displacement points.

[0012] According to the technical solution provided by the present application, after determining that the target section exists on the actual surface, the following steps are further included: Determining whether there is a sudden curvature boundary in the target segment; The obtaining of the first correction sequence corresponding to the target segment comprises the following steps: If not, a first correction sequence corresponding to the target segment is obtained.

[0013] According to the technical solution provided by the present application, after determining whether there is a sudden curvature boundary in the target segment, the following steps are further included: If there is a sudden curvature change boundary in the target section, redundant displacement points are added at the sudden curvature change boundary; Calculating a second displacement deviation of the redundant displacement point based on the number of additional redundant displacement points and the first displacement deviations corresponding to the horizontal displacement points before and after the curvature mutation boundary; A third correction sequence corresponding to the target segment is formed in sequence by the first displacement deviations corresponding to the horizontal displacement points and the second displacement deviations of the redundant displacement points.

[0014] Compared with the prior art, the beneficial effects of the present application are as follows: the present application automatically identifies the mismatched sections (target sections) caused by production errors or process improvements (newly added grooves and other features) by comparing the matching degree between the theoretical arc surface and the actual surface, and generates a first correction sequence including the first displacement deviation of multiple horizontal displacement points in the target section. Compared with the fixed mechanical adaptation method, local deformation can be compensated in real time, so that the nozzle can dynamically track surface depressions or grooves, thereby improving the spacing control accuracy; in addition, there is no need to replace the adapter arc plate or adjust the slot position, and the same device can be used to be compatible with multiple batches of error workpieces and improved products. For workpieces to be sprayed with local depressions, this method can reduce the return spray rate and reduce the cost of equipment modification. Through the constant spacing control of the present application, the waste of overspray of paint is reduced, the consumption of spraying materials is reduced, and at the same time, defects such as sagging and dry spraying caused by sudden changes in spacing are avoided, significantly improving the spraying quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flow chart of the method for online monitoring and self-correction of the spray quality of automotive plastic parts provided in this application; Figure 2A schematic diagram of the structure of the automotive plastic trim spraying device provided in this application; Figure 3 A schematic diagram of the structure of the spray box provided for this application; Figure 4 Provided for this application Figure 3 A partial schematic diagram of the part in the middle; Figure 5 This is a schematic diagram of the structure of the spring provided in this application.

[0016] The text annotations in the figure represent: 1. Spray box; 11. Feed port; 12. Discharge port; 13. Adapter block; 14. Placement slot; 2. Transport assembly; 3. Power assembly; 31. Support column; 32. Screw; 33. Slider; 41. Adapter column; 42. Adapter arc plate; 5. Through slot; 6. Card slot; 71. Accommodating column; 72. Telescopic column; 73. Roller; 74. Spring; 75. Connecting column; 8. Spray nozzle. DETAILED DESCRIPTION

[0017] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0018] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] Example 1 As mentioned in the background technology, in order to solve the problems in the prior art, this application proposes a spraying device for automobile plastic trims, such as Figure 2-5 Shown, including: The spray box 1 is provided with a transport assembly 2, a power assembly 3, an adapter assembly, a moving assembly and a spray head 8. A feed port 11 and a discharge port 12 are provided on the left and right sides of the spray box 1, respectively. The front of the spray box 1 is also provided with a placement slot 14, a through slot 5 and a card slot 6 extending to the back. The placement slot 14 is located below the through slot 5 and the card slot 6, and the front and rear ends of the slider 33 are respectively adapted to be engaged with the inside of the placement slot 14. The card slot 6 is provided at the bottom of the through slot 5, and the inner wall of the card slot 6 is inclined. The two ends of the adapter column 41 are respectively adapted to be engaged with the inside of the card slot 6. An adaptor block 13 is also glued to the top of the inner wall of the spray box 1. The bottom of the adaptor block 13 is in press contact with the top of the adaptor arc plate 42. The adaptor block 13 is made of a rubber block. The power assembly 3 is composed of a support column 31, a lead screw 32 and a slider 33. The support column 31 and the lead screw 32 are fixedly mounted on the front and rear sides of the spray box 1 in sequence. The slider 33 is slidably mounted on the outer surfaces of the support column 31 and the lead screw 32. The moving assembly is fixedly mounted on the top of the slider 33 and includes a receiving column 71. A telescopic column 72 is movably coupled to the inner wall of the receiving column 71. A spring 74 is movably coupled to the outer surface of the telescopic column 72. The spring 74 is mounted with its top end fixed to the upper cover or inner flange of the receiving column 71. Its bottom end is fixed to the side lug of the telescopic column 72. A roller 73 is fixedly coupled to the top of the telescopic column 72. A connecting column 75 is fixedly coupled to the bottom of the telescopic column 72. The bottom of the connecting column 75 is fixedly connected to the nozzle 8. The receiving column 71 is fixedly mounted on the top of the slider 33. The top of the roller 73 is in pressurized contact with the bottom of the adapter assembly. The adapter assembly consists of two symmetrically distributed adapter columns 41 on the left and right. The outer surfaces of the two adapter columns 41 are movably sleeved with an adapter arc plate 42. The adapter arc plate 42 is arched and made of stainless steel. The bottom of the adapter arc plate 42 is in squeeze contact with the roller 73, and the adapter column 41 is adapted to be inserted into the inner wall of the spray box 1; the spring 74 is stretched and arranged inside the accommodating column 71, and the rebound force of the roller 73 is equal to the sum of the reaction force of the roller 73 from the adapter arc plate 42 and the gravity of the nozzle 8.

[0020] Accordingly, when the slider 33 moves horizontally, the spray head 8 will rise and fall precisely, and its motion trajectory completely replicates the arched curvature of the bottom of the fixed arc plate 42. This allows the spray head to evenly spray the plastic automotive trim below along the set arc path during movement.

[0021] Example 2 Based on Example 1, this example proposes a method for online monitoring and self-correction of the spraying quality of automobile plastic parts. Figure 1 As shown, the control method includes the following steps: S1. Obtaining the theoretical position of the slot 6 of the adapter column 41 according to the information of the workpiece to be sprayed, wherein the information includes the type of the workpiece and the area to be sprayed; and the theoretical position of the slot 6 corresponds to the theoretical arc surface of the adapter arc plate 42. Specifically, the information to be sprayed includes the type of workpiece, which is different types of automobile plastic trim such as automobile bumpers, interior panels, rearview mirrors, etc. The area to be sprayed refers to the specific part on the plastic part that needs to be sprayed. Based on this information, the operator can obtain the theoretical slot position of the adapter column 41 corresponding to the different workpiece types and the area to be sprayed according to experience (first, a database is established, and the database stores the theoretical slot position information of the adapter column 41 corresponding to different workpiece types and the area to be sprayed. After the workpiece type and the area to be sprayed information of the workpiece to be sprayed are input, the system can obtain the corresponding theoretical slot position of the adapter column 41 by querying the database. For example, for the bumper of a certain model of automobile, the area to be sprayed is the side, and the database has pre-entered the specific slot number or coordinate position and other information of the adapter column 41 that should be inserted in this case), and the theoretical slot position of the adapter column 41 corresponding to the workpiece to be sprayed that is currently being prepared for spraying can be obtained according to this recorded table.

[0022] S2. Determine whether there is a target section on the actual surface, where the target section is a section on the actual surface that does not match the theoretical cambered surface; the actual surface is the surface of the area to be sprayed of the workpiece to be sprayed; Furthermore, the determining whether the actual surface has a target section that does not match the theoretical cambered surface comprises the following steps: Scanning along a horizontal moving path of the area to be sprayed to obtain a first curvature data set of the actual surface; Specifically, a high-precision 3D laser scanner or other device capable of surface profile detection is used to scan the actual surface along a pre-planned horizontal path across the area to be sprayed. During the scanning process, the device collects coordinate information of each point on the actual surface in real time and converts this coordinate information into corresponding curvature data using a specific algorithm, ultimately forming a first curvature dataset.

[0023] Optionally, the specific algorithm is: Collect three-point coordinates: Take three consecutive scanning points in the detection section: point A (x1, y1, z1), point B (x2, y2, z2), point C (x3, y3, z3), and calculate the length of the triangle side: , (the same goes for the other sides BC and AC), calculate the area of the triangle (Heron's formula): , where S represents the area of the triangle and p represents the semiperimeter. The calculation formula is p = (AB + BC + AC) / 2, and the circumscribed circle radius R = (AB × BC × AC) / 4S. The actual curvature is the reciprocal of the circumscribed circle radius R. The above algorithm can be used to convert the coordinates of each point on the actual surface into the corresponding actual curvature data.

[0024] Using the theoretical arc surface as a reference surface, discretizing the first curvature data set to divide it into a plurality of detection sections; For example, taking equal distance intervals as an example, the first curvature data set is divided into 10 mm segments, so that the continuous first curvature data is divided into a plurality of detection segments. Each detection segment contains curvature information corresponding to an actual surface area of 10 mm in length.

[0025] The first deviation value between the actual curvature radius and the theoretical curvature radius in each of the detection segments is calculated. If the first deviation value corresponding to at least one of the detection segments is greater than a preset curvature tolerance threshold, it is determined that there is a target segment on the actual surface that does not match the theoretical curved surface.

[0026] Specifically, for each detection section, the corresponding geometric formula (derived from the curvature data in the detection section, specifically the actual curvature data of points A, B, C, D, E and F in the detection section obtained by the above specific algorithm, is used to calculate the curvature of the points A, B, C, D, E and F in the detection section) Get the actual curvature radius, where R 实际 Indicates the actual curvature radius of the detection section, Q A To Q F The actual curvature radius is calculated using the actual curvature data (representing the actual curvature data for each point within the inspection segment). Simultaneously, the theoretical curvature radius at the corresponding location is calculated based on the mathematical model of the theoretical curved surface. The difference between the two values, known as the first deviation value, is then calculated. A preset curvature tolerance threshold can be set based on actual production requirements and empirical values, such as 0.3mm. If the first deviation value for any inspection segment exceeds 0.3mm, the actual surface is determined to contain a target segment that does not match the theoretical curved surface.

[0027] This implementation method is based on a comparative analysis of the curvature of actual surfaces and theoretical curved surfaces. Curvature data of the actual surface is obtained through scanning and then discretized and compared with the curvature of the theoretical curved surface. Since curvature reflects the degree of curvature of a surface, when the actual curvature radius deviates significantly from the theoretical curvature radius, it indicates that the actual surface and the theoretical curved surface at that location are inconsistent, indicating that there is a mismatched target segment. This curvature comparison method can more accurately detect differences in surface shape and is more sensitive to subtle surface deformations or unevenness than simple distance comparison.

[0028] S3. If yes, obtain a first correction sequence corresponding to the target segment, where the first correction sequence includes a plurality of horizontal displacement points that the nozzle passes through during horizontal movement within the target segment, and a first displacement deviation corresponding to each horizontal displacement point; Specifically, once an area is identified where the deviation between the actual surface and the theoretical camber exceeds the allowable range, it is directly marked as a target section by color marking or setting a special mark. Since the horizontal displacement points are known and set in advance, these preset uniformly distributed horizontal point data are directly called. For each target section, based on these known horizontal displacement points, the displacement adjustment amount required for the nozzle 8 to maintain a preset constant distance from the actual surface at each point is calculated. This position adjustment amount is the first displacement deviation amount corresponding to the horizontal displacement point. Using the three-dimensional scanning data, the actual surface is compared with the theoretical camber. At each horizontal displacement point, the vertical distance difference between the actual surface and the theoretical camber is calculated, that is, the height deviation value. For example, there are 10 horizontal displacement points in a target section. Through comparison, it is calculated that at the first horizontal displacement point, the actual surface is 0.8 mm lower than the theoretical camber, and at the second horizontal displacement point, the actual surface is 0.5 mm lower than the theoretical camber, and so on. For example, a target section has seven evenly distributed horizontal displacement points. When the nozzle 8 is at the first horizontal displacement point, the first displacement deviation corresponding to the first horizontal displacement point is calculated based on the deviation between the actual surface of the target section and the theoretical arc surface, so that the nozzle 8 maintains a preset constant distance from the first horizontal displacement point of the actual surface consistent with other areas; the same treatment is performed at the second horizontal displacement point, and so on, and the corresponding first displacement deviation is determined for each horizontal displacement point, thereby forming a complete first correction sequence for the target section.

[0029] S4. After the adapter column 41 is inserted into the theoretical slot 6 position, the nozzle 8 is controlled to perform the spraying operation along the horizontal movement path, and the corresponding first correction sequence is executed in each target section so that the nozzle 8 always maintains a preset constant distance from the actual surface of the area to be sprayed.

[0030] Specifically, during the actual spraying operation, the adapter post 41 is accurately positioned into the previously determined theoretical slot 6 position, either manually or through an automated mechanism. The spraying device is then activated, and the spray head 8 begins spraying along a preset horizontal movement path. When the spray head 8 moves within the target section, the system automatically invokes the corresponding first correction sequence and adjusts the position of the spray head 8 in real time based on the horizontal displacement points in the first correction sequence and the corresponding first displacement deviation.

[0031] The technical principle is described as follows: This control method is based on feedback control and adaptive adjustment. First, based on known information about the workpiece to be sprayed, the theoretical spray parameters and position (i.e., the theoretical position of the slot 6 of the adapter column 41 and the corresponding theoretical curved surface) are determined. However, due to production errors in the sprayed surface of certain batches of workpieces, or due to process improvements, some areas may not match the curved surface of the original adapter plate 42 (this solution is only applicable to cases with concave surfaces, because the adapter plate interferes with the telescopic column at the upper end, preventing it from compensating for convexities). In such cases, a simple mechanical automotive plastic trim spraying device cannot achieve uniform spraying. In this case, by comparing the actual surface with the theoretical curved surface, the mismatched target sections are identified. Adaptive adjustment is then performed for these target sections using a precalculated first correction sequence. The horizontal displacement points are set to precisely control the position of the nozzle 8 within the target section, enabling targeted correction of deviations at different locations to ensure a constant, preset distance between the nozzle 8 and the workpiece surface, ensuring consistent spray quality.

[0032] In a preferred embodiment, after calculating the first deviation between the actual curvature radius and the theoretical curvature radius in each detection section, the following steps are further included: The detection section where the first deviation value is greater than a preset curvature tolerance threshold is regarded as a primary abnormal section; Specifically, the detection segments whose first deviation values are greater than the preset curvature tolerance threshold are directly screened out and marked as primary abnormal segments. For example, among all the detection segments, if the first deviation values of five detection segments are greater than the preset 0.5mm threshold, then these five detection segments are identified as primary abnormal segments.

[0033] Performing curvature continuity analysis on adjacent primary abnormal sections and calculating the curvature change rate between adjacent detection points; Specifically, for adjacent primary anomaly segments, their adjacent detection points are first determined. Then, the curvature data for these two adjacent detection points is obtained. The curvature change rate is calculated using the formula: Curvature change rate = (curvature of the next detection point - curvature of the previous detection point) / distance between the two points. For example, for adjacent detection points in two adjacent primary anomaly segments, if the curvature of the previous point is 0.02 and the curvature of the next point is 0.08, and the distance between the two points is 5 mm, then the curvature change rate = (0.08 - 0.02) / 5 = 0.012.

[0034] If the curvature change rate is greater than the first change rate, it is determined that a curvature mutation boundary exists; Specifically, the calculated curvature change rate is compared with a pre-set first change rate. The first change rate can be set based on actual production experience and product surface quality requirements, such as 0.01. If the calculated curvature change rate is greater than 0.01, it is determined that a curvature mutation boundary exists between the two adjacent detection points.

[0035] According to the spatial distribution characteristics of the curvature mutation boundary, more than N consecutive primary abnormal sections with the same-direction curvature deviation are merged into the same target section.

[0036] Specifically, all primary anomaly segments are traversed to observe the distribution of curvature mutation boundaries between them. The curvature deviation direction of each primary anomaly segment is also determined (whether it is greater than or less than the theoretical curvature radius). If N or more consecutive primary anomaly segments (N can be set based on actual conditions, such as 3) are found to have the same curvature deviation direction, and there are no curvature mutation boundaries between them or the curvature mutation boundaries are within a reasonable range, these primary anomaly segments are merged into a single target segment. For example, if there are four consecutive primary anomaly segments, their actual curvature radii are all greater than the theoretical curvature radius, and their curvature change rates are all less than the first change rate, then these four primary anomaly segments are merged into a single target segment.

[0037] This implementation is based on an analysis of the curvature continuity and deviation direction of primary anomaly segments. By studying the curvature change rate between adjacent detection points, it is possible to determine whether the surface curvature changes smoothly, thereby identifying the boundaries of sudden curvature changes. Consecutive primary anomaly segments with the same curvature deviation are merged because these areas have similar curvature characteristics and may be mismatched with the theoretical curved surface due to the same reasons (such as mold manufacturing errors). Merging them into a single target segment facilitates more efficient and accurate subsequent correction operations.

[0038] In a preferred embodiment, after the adapter column 41 is inserted into the theoretical slot 6 and before the nozzle 8 is controlled to move along the horizontal path for spraying, the following steps are further included: Controlling the no-load horizontal movement of the nozzle 8 to obtain a calibration arc curve of the path traveled by the nozzle 8; wherein, during the no-load horizontal movement of the nozzle 8, the corresponding first correction sequence is not executed and the nozzle 8 does not spray paint liquid; Specifically, before the actual spraying operation begins, the spraying device's mobile assembly is activated, controlling the spray head 8 to move unloaded along a pre-set horizontal path. During this movement, a position sensor mounted on the spray head 8 or the mobile assembly collects real-time position information about the spray head 8. Based on this position information, a curve representing the path traversed by the spray head 8 is plotted, known as the calibration curve. For example, the position sensor collects the coordinates of the spray head 8 every 0.1 seconds, and these coordinate points are connected to form the calibration curve.

[0039] Judging whether the theoretical position of the card slot 6 is credible according to the calibration arc curve and the theoretical arc curve corresponding to the theoretical arc surface; Specifically, the resulting calibration curve is compared with a theoretical curve pre-calculated based on the theoretical slot 6 position and the theoretical arc surface. A curve fit analysis algorithm can be used to calculate the fit of the two curves. If the fit exceeds a predetermined standard value (e.g., 90%), the theoretical slot 6 position is considered reliable; otherwise, it is considered that there may be a deviation in the theoretical slot 6 position. For example, if the curve fit analysis algorithm calculates that the fit between the calibration curve and the theoretical curve is 92%, since 92% is greater than 90%, the theoretical slot 6 position is considered reliable.

[0040] The control of the nozzle 8 to perform spraying operation along the horizontal moving path includes the following steps: If so, the nozzle 8 is controlled to perform spraying operation along the horizontal moving path.

[0041] Specifically, after it is determined that the theoretical position of the card slot 6 is credible, the paint spraying system of the spraying device is started, and at the same time, the spray head 8 is kept moving along the preset horizontal moving path to start the formal spraying operation.

[0042] This embodiment is based on a comparison of the no-load travel path of the nozzle 8 and the theoretical path. If the theoretical slot 6 is positioned correctly, then the no-load travel path of the nozzle 8 should be close to the theoretical arc curve. By comparing the fit of the two curves, it is possible to indirectly determine whether the theoretical position of the slot 6 is correct. This is because the theoretical position of the slot 6 determines the position of the adapter plate 42, which in turn affects the initial position and travel path of the nozzle 8. If the theoretical position of the slot 6 is incorrect, the actual travel path of the nozzle 8 (the calibration arc curve) will deviate significantly from the theoretical arc curve.

[0043] In a preferred embodiment, if the actual surface has a target section that does not match the theoretical curved surface, the method further includes the following steps: determining a position range of the target section on the horizontal moving path; Determine whether the position range is mapped to the two end regions of the adaptive arc plate 42, where the two end regions of the adaptive arc plate 42 are the ranges along the length direction thereof that are greater than a preset distance threshold from the center point; The obtaining of the first correction sequence corresponding to the target segment comprises the following steps: If not, a first correction sequence corresponding to the target segment is obtained.

[0044] Specifically, obtain the horizontal coordinate boundary and extract the coordinate values of the starting point and the ending point of the target segment in the horizontal moving direction (X axis). For example, if the target segment covers the horizontal path from X=550m to X=580m, the position range is [150, 350]. Mapping to the spraying device coordinate system: Convert the workpiece coordinates to the spray box coordinate system (such as Figure 2-5 As shown), ensure that the physical position of the adaptation arc plate 42 is aligned. Optionally, the preset distance threshold is 1 / 6 of the total length of the adaptation arc plate 42.

[0045] For example, if the length of the adaptive arc plate 42 is 600m, the range of both ends exceeding 100m from the center point belongs to the end region. That is, the area 100m measured from each end head is the end region. If the right end region of the arc plate is X = [500, 600], then the target section covers the horizontal path from X = 550m to X = 580m belongs to the right end region of the adaptive arc plate 42, and it is determined that the position range is mapped to the end region of the adaptive arc plate 42. If the left end region of the arc plate is X = [0, 100], and the target section covers the horizontal path from X = 200m to X = 270m, then it is determined that the position range is not mapped to the end region of the adaptive arc plate 42. In this case, the acquisition process of the first correction sequence can be executed.

[0046] This embodiment takes into account the unique properties of the mechanical structure. When the roller 73 moves to the two ends of the arc plate, the spring 74 is stretched to the maximum deformation state due to the reduction in the arc height. If the first correction sequence is executed in the two end areas, it is very likely that the spring will be stretched again at a certain point. Therefore, active pull-down correction is disabled in the two end areas of the arc plate (high-risk areas for the spring) to avoid overload failure of the spring 74.

[0047] Furthermore, after determining whether the position range is mapped to the two end areas of the adaptation arc plate 42, the following steps are further included: Acquire all first displacement deviations in the first correction sequence corresponding to the target segment; Determining whether each of the first displacement deviations exceeds a safety displacement threshold, the safety displacement threshold being the maximum allowable compensation displacement of the spring while ensuring reliability and preventing plastic deformation; Specifically, each horizontal displacement point has a corresponding safety displacement threshold. For each adapting arc plate 42 and spring 74, each horizontal displacement point has a corresponding deformation of the spring 74, which can be obtained by measuring the displacement of the telescopic column 72 relative to the accommodating column 71 in real time through a laser displacement sensor. The safety displacement threshold corresponding to the point can be obtained by subtracting the corresponding deformation at the point from the maximum elongation of the spring 74. For example, if the current deformation of the spring 74 at a horizontal displacement point is 3 mm, if the maximum elongation of the spring is 10 mm, then the safety displacement threshold corresponding to the horizontal displacement point is 7 mm.

[0048] The step of executing the corresponding first correction sequence in the target segment comprises the following steps: If all the first displacement deviations do not exceed the safety displacement threshold, the corresponding first correction sequence is executed in the target section.

[0049] Specifically, a safety displacement threshold database can be obtained in the above manner before spraying begins. The database includes multiple horizontal displacement points and the safety displacement threshold corresponding to each horizontal displacement point. The safety displacement threshold database is retrieved and traversed, and the first displacement deviation of each horizontal displacement point is compared with the corresponding safety displacement threshold. After comparing one by one, it is determined whether all first displacement deviations do not exceed the safety displacement threshold. If they do not exceed the safety displacement threshold, it means that the corresponding first correction sequence can be pulled down to execute.

[0050] In this embodiment, in areas where there may be a risk of tensile failure at both ends of the arc plate, it is first determined whether additional downward pulling will cause the spring 74 to fail. If it is determined that it will not cause the spring 74 to fail, additional stretching is added to reduce the risk of spring 74 failure.

[0051] Furthermore, after determining whether each of the first displacement deviations exceeds a preset safety displacement threshold, the following steps are further included: If at least one of the first displacement deviations exceeds the safety displacement threshold, the horizontal displacement point corresponding to the first displacement deviation exceeding the safety displacement threshold is marked as a displacement point to be corrected; Correcting the first displacement deviations corresponding to all the displacement points to be corrected in the first correction sequence to the safety displacement threshold to obtain a second correction sequence corresponding to the target section; After the adapter column 41 is locked into the theoretical slot position, the spray head 8 is controlled to perform a spraying operation along a horizontal movement path, and the corresponding second correction sequence is executed in the target section.

[0052] Specifically, if any first displacement deviation exceeds the safe displacement threshold, the point to be corrected is marked and added to the set to be corrected. A second correction sequence is generated: the first displacement deviation of the point to be corrected in the original first correction sequence is replaced with the safe displacement threshold. This ensures that, while ensuring that spring 74 does not fail, the nozzle 8 is pulled down as far as possible to maintain a preset constant distance from the actual surface. This embodiment prioritizes mechanical protection. Exceeding the limit displacement indicates a potential failure of spring 74, and forcibly cutting off the displacement can prevent structural damage.

[0053] In a preferred embodiment, executing the corresponding first correction sequence in the target segment comprises the following steps: The linear actuator installed on the side wall of the accommodating column 71 is controlled to perform a corresponding displacement of the first displacement deviation when the spray head 8 moves to each of the horizontal displacement points.

[0054] Specifically, the linear actuator type is a micro servo cylinder with a built-in displacement sensor, which is installed horizontally on the outer wall of the receiving column 71. The push rod axis of the linear brake is parallel to the telescopic column 72 ( Figure 2-5 The distal end of the linear actuator's push rod (in the Y-axis direction) is connected to the lateral lug of telescopic column 72 via a universal joint (to prevent interference with the axial movement of spring 74). The linear actuator activates auxiliary compensation only when the spring's compensation margin is insufficient, and its output force always aligns with the direction of spring deformation.

[0055] Specifically, as the printhead 8 moves to each horizontal displacement point, the system sends a control signal to the linear actuator mounted on the sidewall of the receiving column 71 based on the first correction sequence calculated in the previous step. Upon receiving the signal, the linear actuator controls its output terminal to drive the connecting column 75 to move the corresponding distance based on the displacement instruction in the signal (corresponding to the first displacement deviation at each horizontal displacement point in the first correction sequence), so that the printhead 8 reaches the target position.

[0056] In this embodiment, the linear actuator is used to precisely control the position of the nozzle 8 to ensure a preset distance between the nozzle 8 and the workpiece surface.

[0057] In a preferred embodiment, after determining that the target section exists on the actual surface, the method further includes the following steps: Determining whether there is a sudden curvature boundary in the target segment; The obtaining of the first correction sequence corresponding to the target segment comprises the following steps: If not, a first correction sequence corresponding to the target segment is obtained.

[0058] Furthermore, after determining whether there is a sudden curvature change boundary in the target section, the method further includes the following steps: If there is a sudden curvature change boundary in the target section, redundant displacement points are added at the sudden curvature change boundary; Calculating a second displacement deviation of the redundant displacement point based on the number of additional redundant displacement points and the first displacement deviations corresponding to the horizontal displacement points before and after the curvature mutation boundary; A third correction sequence corresponding to the target segment is formed in sequence by the first displacement deviations corresponding to the horizontal displacement points and the second displacement deviations of the redundant displacement points.

[0059] Specifically, redundant displacement points are additional horizontal displacement points added at curvature-sharp boundaries within the target section to facilitate smoother transitions in the position adjustment of the nozzle 8. These points are used to more finely adjust the position of the nozzle 8 in areas of sudden curvature to ensure a smooth change in the distance between the nozzle 8 and the workpiece surface. For example, when a curvature mutation boundary is identified at 250 mm, two redundant displacement points are inserted between the adjacent original displacement points before and after the mutation point. Specifically, points 250.33 mm and 250.67 mm are inserted between 250 mm and 251 mm. The redundant point compensation amount is calculated (gradually progressive method) to obtain the compensation amount of the original points on both sides of the mutation boundary: the front point (250 mm) needs to be pressed down by 0.6 mm, and the rear point (251 mm) needs to be pressed down by 1.8 mm. Since there are two redundant points ((1.8-0.6) / 3=0.4, each redundant point increases by 0.4), the second displacement deviation amount of the redundant point close to the front point is 0.6+0.4=1, and the second displacement deviation amount of the redundant point close to the rear point is 0.6+0.4+0.4=1.4.

[0060] Specifically, the first displacement deviations calculated at each horizontal displacement point within the original target segment and the newly calculated second displacement deviations at each redundant displacement point are arranged sequentially in order of horizontal displacement. This is used to refine the position adjustment of the nozzle 8 within the target segment with a sudden change in curvature by adding redundant displacement points. This ensures a smooth transition in the distance between the nozzle 8 and the workpiece surface as it passes through this sudden change in curvature, avoiding spray quality issues caused by this sudden change in distance. This approach is based on refined processing of complex surface shapes (those with sudden changes in curvature) to meet the requirements of high-precision spraying.

[0061] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of the present invention, they can also make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A control method for online monitoring and self-correction of the spraying quality of automobile plastic parts, which is implemented based on an automobile plastic trim spraying device, the device comprising a spray box (1), an adapter component, a moving component and a spray head (8), wherein the adapter component matches the workpiece surface through the curvature of the adapter arc plate (42), and the moving component drives the spray head (8) to rise and fall synchronously with the adapter arc plate (42) through a spring (74) and a telescopic column (72); characterized in that The control method comprises the following steps: According to the to-be-sprayed information of the workpiece to be sprayed, a theoretical slot position of the adapter column (41) is obtained; the to-be-sprayed information includes the type of the workpiece and the area to be sprayed; the theoretical slot position corresponds to a theoretical arc surface of the adapter arc plate (42); Determining whether there is a target section on the actual surface, the target section being a section on the actual surface that does not match the theoretical cambered surface; the actual surface being the surface of the area to be sprayed of the workpiece to be sprayed; If so, a first correction sequence corresponding to the target section is obtained, wherein the first correction sequence includes a plurality of horizontal displacement points that the nozzle (8) passes through during horizontal movement within the target section, and a first displacement deviation corresponding to each of the horizontal displacement points; After the adapter column (41) is locked into the theoretical slot position, the nozzle (8) is controlled to perform a spraying operation along a horizontal movement path, and the corresponding first correction sequence is executed within the target section, so that the nozzle and the actual surface of the area to be sprayed always maintain a preset constant distance.

2. The method for online monitoring and self-correction of spray coating quality of automotive plastic parts according to claim 1, characterized in that: The determining whether the actual surface has a target section that does not match the theoretical cambered surface comprises the following steps: Scanning along a horizontal moving path of the area to be sprayed to obtain a first curvature data set of the actual surface; Using the theoretical arc surface as a reference surface, discretizing the first curvature data set to divide it into a plurality of detection sections; The first deviation value between the actual curvature radius and the theoretical curvature radius in each of the detection segments is calculated. If the first deviation value corresponding to at least one of the detection segments is greater than a preset curvature tolerance threshold, it is determined that there is a target segment on the actual surface that does not match the theoretical curved surface.

3. The method for online monitoring and self-correction of spray coating quality of automotive plastic parts according to claim 2, characterized in that: After calculating the first deviation value between the actual curvature radius and the theoretical curvature radius in each detection section, the method further includes the following steps: The detection section where the first deviation value is greater than a preset curvature tolerance threshold is regarded as a primary abnormal section; Performing curvature continuity analysis on adjacent primary abnormal sections and calculating the curvature change rate between adjacent detection points; If the curvature change rate is greater than the first change rate, it is determined that a curvature mutation boundary exists; According to the spatial distribution characteristics of the curvature mutation boundary, more than N consecutive primary abnormal sections with the same-direction curvature deviation are merged into the same target section.

4. The method for online monitoring and self-correction of spray coating quality of automotive plastic parts according to claim 1, characterized in that: After the adapter column (41) is locked into the theoretical slot position, before the nozzle (8) is controlled to move along the horizontal movement path to perform the spraying operation, the following steps are also included: Controlling the nozzle (8) to move horizontally without load to obtain a calibration arc curve of the path taken by the nozzle (8); wherein, during the horizontal movement of the nozzle (8) without load, the corresponding first correction sequence is not executed and the nozzle does not spray paint liquid; judging whether the theoretical slot position is credible according to the calibration arc curve and the theoretical arc curve corresponding to the theoretical arc surface; The control nozzle (8) performs spraying operation along a horizontal moving path, comprising the following steps: If so, the nozzle (8) is controlled to perform spraying operation along the horizontal moving path.

5. The method for online monitoring and self-correction of spray coating quality of automotive plastic parts according to claim 1, characterized in that: If the actual surface has a target section that does not match the theoretical curved surface, the method further includes the following steps: determining a position range of the target section on the horizontal moving path; Determining whether the position range is mapped to the two end areas of the adaptive arc plate (42), the two end areas of the adaptive arc plate (42) being the range along its length direction and the distance from the center point exceeding a preset distance threshold; The obtaining of the first correction sequence corresponding to the target segment comprises the following steps: If not, a first correction sequence corresponding to the target segment is obtained.

6. The method for online monitoring and self-correction of spray coating quality of automotive plastic parts according to claim 5, characterized in that: After determining whether the position range is mapped to the two end areas of the adaptation arc plate (42), the following steps are also included: Acquire all first displacement deviations in the first correction sequence corresponding to the target segment; Determining whether each of the first displacement deviations exceeds a safety displacement threshold, the safety displacement threshold being the maximum compensation displacement that the spring (74) can allow while ensuring reliability and preventing plastic deformation; The step of executing the corresponding first correction sequence in the target segment comprises the following steps: If all the first displacement deviations do not exceed the safety displacement threshold, the corresponding first correction sequence is executed in the target section.

7. The method for online monitoring and self-correction of spray coating quality of automobile plastic parts according to claim 6, characterized in that: After determining whether each of the first displacement deviations exceeds a preset safety displacement threshold, the following steps are further included: If at least one of the first displacement deviations exceeds the safety displacement threshold, the horizontal displacement point corresponding to the first displacement deviation exceeding the safety displacement threshold is marked as a displacement point to be corrected; Correcting the first displacement deviations corresponding to all the displacement points to be corrected in the first correction sequence to the safety displacement threshold to obtain a second correction sequence corresponding to the target section; After the adapter column (41) is locked into the theoretical slot position, the spray head (8) is controlled to perform a spraying operation along a horizontal movement path, and the corresponding second correction sequence is executed within the target section.

8. The method for controlling the online monitoring and self-correction of the spray coating quality of automobile plastic parts according to claim 1, characterized in that: The step of executing the corresponding first correction sequence in the target segment comprises the following steps: A linear actuator installed on the side wall of the accommodating column (71) is controlled to perform a corresponding displacement of the first displacement deviation when the nozzle (8) moves to each of the horizontal displacement points.

9. The method for controlling the online monitoring and self-correction of the spraying quality of automobile plastic parts according to claim 1, characterized in that: After determining that the target section exists on the actual surface, the method further includes the following steps: Determining whether there is a sudden curvature boundary in the target segment; The obtaining of the first correction sequence corresponding to the target segment comprises the following steps: If not, a first correction sequence corresponding to the target segment is obtained.

10. The method for controlling the online monitoring and self-correction of the spraying quality of automobile plastic parts according to claim 9, characterized in that: After determining whether there is a sudden curvature boundary in the target section, the following steps are further included: If there is a sudden curvature change boundary in the target section, redundant displacement points are added at the sudden curvature change boundary; Calculating a second displacement deviation of the redundant displacement point based on the number of additional redundant displacement points and the first displacement deviations corresponding to the horizontal displacement points before and after the curvature mutation boundary; A third correction sequence corresponding to the target segment is formed in sequence by the first displacement deviations corresponding to the horizontal displacement points and the second displacement deviations of the redundant displacement points.

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