Method for adjusting ink-jet uniformity of photocuring 3D printing by using cylinder

Abstract

The invention discloses a photocuring 3D printing ink-jet uniformity adjusting method using a cylinder, and relates to the technical field of ink-jet uniformity adjusting, and the method comprises the steps: calculating the curvature according to the geometrical characteristics of the cylinder, calculating the vertex and inflection point of the cylinder according to the curvature, calculating the vertex and inflection point through which a nozzle needs to pass according to a non-planar path planning algorithm, and adjusting the uniformity of the photocuring 3D printing ink-jet uniformity. The method comprises the following steps: generating a UV curing ink printer nozzle motion trail, setting ink jet parameters according to a curing rate, adjusting the nozzle motion speed based on a cylinder curvature, applying an ink jet time sequence to a cylinder edge area to compensate and offset centrifugal offset, and carrying out ink jet on a cylinder based on the nozzle motion trail, the nozzle motion speed and the ink jet parameters. And a K-means clustering algorithm is used to identify a non-uniform ink jet area. According to the method, the technical problem of non-uniform ink jetting in the 3D printing process is solved through a non-planar path planning algorithm, and the quality and production efficiency of a final product are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inkjet uniformity adjustment, and particularly to a method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder. Background Art

[0002] With the rapid development of 3D printing technology, especially the progress of stereolithography (SLA) and continuous liquid interface production (CLIP) technology, the manufacturing industry has obtained unprecedented flexibility in product design and rapid prototyping. These technologies build three-dimensional entities by curing liquid photosensitive resin, which not only reduces the workload of manual inspection but also improves the detection accuracy. Finally, the improvement of the surface consistency and aesthetics of products and the ability to handle complex geometries have made them highly favored.

[0003] Despite the progress, UV-curing inkjet printers still face challenges when dealing with cylinders. Specifically, achieving uniform coating during the inkjet process has become a major problem. Especially in the face of different curvature changes, it is difficult for previous methods to ensure the consistency of the coating. In addition, the influence of temperature changes on the curing rate of UV-curing ink is also a factor that cannot be ignored. It not only affects the printing efficiency but also may lead to unstable quality of the finished product. Summary of the Invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder to solve the problem of difficult uniform coating during the inkjet process.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: In the first aspect, the present invention provides a method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder, which includes importing a three-dimensional model of the target cylinder using CAD software and selecting a photosensitive resin adapted to the 3D printer; Loading the photosensitive resin into the 3D printer and printing and curing according to the three-dimensional model of the cylinder to obtain a cylinder; Calculating the curvature according to the geometric characteristics of the cylinder and generating the movement trajectory of the UV-curing inkjet printer nozzle using a non-planar path planning algorithm; Quantifying the influence of temperature on the curing rate using a curing reaction kinetics mechanism, setting inkjet parameters, and at the same time adjusting the movement speed of the nozzle to apply inkjet timing compensation at the edge area of the cylinder to offset the centrifugal offset; Based on the nozzle movement trajectory, nozzle movement speed, and inkjet parameters, inkjet printing is performed on the cylinder. After completion, a 3D surface topography of the cylinder is obtained using a laser scanner, and the uneven inkjet areas are identified using the K-means clustering algorithm. Local photocuring is used to perform directional correction on the uneven inkjet areas.

[0007] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing of cylinders according to the present invention, wherein: importing the 3D model of the target cylinder using CAD software and selecting a photosensitive resin adapted to the 3D printer, specifically: Import the 3D model of the target cylinder using AutoCAD software and convert the 3D model of the cylinder into STL format; Import the 3D model of the cylinder in STL format into the 3D printer CLIP; Select a photosensitive resin that meets the requirements of the 3D printer CLIP as the printing material.

[0008] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing of cylinders according to the present invention, wherein: loading the photosensitive resin into the 3D printer and printing and curing according to the 3D model of the cylinder to obtain the cylinder, specifically: Load the photosensitive resin into the 3D printer CLIP and perform preliminary calibration; Start the 3D printer CLIP to print the cylinder and perform synchronous printing and curing through the photosensitive resin.

[0009] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing of cylinders according to the present invention, wherein: calculating the curvature according to the geometric characteristics of the cylinder, calculating the vertices and inflection points of the cylinder according to the curvature, calculating the vertices and inflection points that the nozzle needs to pass through according to the non-planar path planning algorithm, and generating the movement trajectory of the UV-curing inkjet printer nozzle, specifically: Calculate the angular change between all adjacent vertices using the vertices in the geometric characteristics of the cylinder and take the average value as the curvature of the cylinder; According to the vertices and inflection points of the cylinder, use the B-spline curve path planning algorithm to calculate the vertices and inflection points that the nozzle needs to pass through, and at the same time connect the vertices and inflection points to form the nozzle movement trajectory, and make the nozzle always perpendicular to the normal direction of the cylinder surface.

[0010] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing of cylinders according to the present invention, wherein: using the curing reaction kinetics mechanism to quantify the influence of temperature on the curing rate, setting the inkjet parameters according to the curing rate, adjusting the nozzle movement speed based on the cylinder curvature, and applying inkjet timing compensation at the edge area of the cylinder to offset the centrifugal offset, specifically: According to the chemical composition of the UV-curable ink and its curing behavior at different temperatures, use the Arrhenius equation to quantify the effect of temperature on the curing rate, and set the inkjet parameters; Adjust the nozzle movement speed based on the curvature of the cylinder, and at the same time, use a compensation algorithm to calculate the inkjet compensation time according to the centrifugal force of the nozzle in the edge area of the cylinder.

[0011] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder according to the present invention, wherein: the inkjetting on the cylinder based on the nozzle movement trajectory, nozzle movement speed and inkjet parameters is specifically as follows: Adjust the distance between the nozzle of the UV-curable ink printer and the surface of the cylinder, and input the nozzle movement trajectory, nozzle movement speed and inkjet parameters into the control software of the UV-curable ink printer for parameter setting; Start the UV-curable ink printer to perform inkjetting on the cylinder, and at the same time, monitor the working state of the nozzle in real time during the inkjetting process; After the inkjetting is completed, place the cylinder under the UV light source for curing.

[0012] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder according to the present invention, wherein: after completion, use a laser scanner to obtain the three-dimensional topography of the cylinder surface and use the K-means clustering algorithm to identify the inkjet non-uniform area, specifically as follows: Fix the cylinder on the rotating platform, and use a laser scanner to perform a comprehensive scan to record the data points of laser reflection in real time; Calculate the height difference of each data point and map it to the corresponding coordinate system, and use the K-means clustering algorithm to calculate the deviation degree of all data points in the coordinate area relative to the average height to identify the inkjet non-uniform area.

[0013] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder according to the present invention, wherein: the local photocuring and retouching is used to perform directional correction on the inkjet non-uniform area, specifically as follows: Modify the original nozzle path based on the coordinates of the inkjet non-uniform area to obtain the retouching path; Readjust the nozzle parameters according to the area size of the retouching area and the required coating thickness; Use the UV-curable ink printer to perform re-spraying in the retouching area, and immediately start the UV light source to irradiate the newly sprayed ink after the spraying of each retouching area is completed, so that the ink cures quickly.

[0014] In a second aspect, the present invention provides a computer device, including a memory and a processor, where the memory stores a computer program, and: when the computer program is executed by the processor, any step of the method for adjusting the inkjet uniformity of stereolithography 3D printing using a cylinder as described in the first aspect of the present invention is implemented.

[0015] In a third aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored, and: when the computer program is executed by the processor, any step of the method for adjusting the inkjet uniformity of stereolithography 3D printing using a cylinder as described in the first aspect of the present invention is implemented.

[0016] The beneficial effects of the present invention are as follows: By adopting a non-planar path planning algorithm to calculate the curvature according to the geometric characteristics of the cylinder and generate the nozzle movement trajectory, the problem of uneven inkjet caused by uneven surface is effectively solved. At the same time, by combining the curing reaction kinetics mechanism to quantify the influence of temperature on the curing rate, the curing efficiency and coating thickness control are optimized, ensuring the stability of the finished product quality. After the preliminary printing is completed, the K-means clustering algorithm is used to identify the uneven inkjet area and perform local stereolithography supplementary coating directional correction, reducing the workload of manual inspection, greatly improving the detection accuracy and production efficiency. The organic combination of these innovative technologies not only solves the problem of uneven inkjet encountered in the traditional 3D printing process, but also greatly improves the surface consistency and aesthetics of the product, reduces resource waste, and improves the overall production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings according to these drawings without creative efforts.

[0018] Figure 1 It is a flowchart of the method for adjusting the inkjet uniformity of stereolithography 3D printing using a cylinder.

[0019] Figure 2 It is a schematic diagram of the parameter adjustment mechanism.

[0020] Figure 3 It is a schematic diagram of the device structure.

[0021] Figure 4 It is a schematic diagram of the detection and correction. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be made in conjunction with the accompanying drawings of the specification.

[0023] In the following description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0024] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or alternative embodiments that exclude each other from other embodiments.

[0025] Referring to Figures 1 to 4 , which is an embodiment of the present invention. This embodiment provides a method for adjusting the inkjet uniformity of light-curing 3D printing using a cylinder, including the following steps: S1. Import the three-dimensional model of the cylinder through CAD software and select the photosensitive resin adapted to the 3D printer CLIP. Specifically: Open the AutoCAD software, click "Import" in the "File" menu, and then select the three-dimensional model file of the target cylinder. Ensure that the imported three-dimensional model of the cylinder is correctly displayed in the view, and measure the height and diameter of the cylinder through the built-in measurement function of the AutoCAD software. When it is found that the measured dimensions of the cylinder are higher or lower than the target and the diameter is inaccurate, correct the three-dimensional model of the cylinder through stretching and scaling of the AutoCAD software.

[0026] Select RPU 70 photosensitive resin as the printing material for the 3D printer CLIP. It is suitable for manufacturing strong and durable functional components, and at the same time can provide high resolution and smooth surface finish for rapid production of high-quality industrial-grade parts, which is particularly important for realizing cylinders with fine structures and complex shapes.

[0027] S2. Load the photosensitive resin into the CLIP printer and print and cure according to the three-dimensional model of the cylinder. Specifically: Prepare according to the determined RPU70 photosensitive resin, and confirm that the storage conditions (temperature, light avoidance) of the RPU70 photosensitive resin meet the requirements to ensure performance.

[0028] Turn on the power of the CLIP printer to start and enter the main interface. On the main interface, select the "Maintenance" option, run the self-test, and check whether all mechanical components, such as the printing platform, projection module, and liquid tank, are working properly. Any abnormalities should be eliminated immediately. After checking for no abnormalities, open the liquid tank cover of the CLIP printer, pour the selected RPU 70 photosensitive resin into the liquid tank, taking care not to exceed the maximum marking line. After installation, close the liquid tank cover to ensure good sealing and prevent leakage during printing.

[0029] Return to the control panel of the CLIP printer and select the "Calibration" function. Complete various calibration operations according to the on-screen prompts, such as Z-axis height adjustment and laser focusing. After calibration, use a standard test piece for test printing to verify whether the printing accuracy and quality meet the expected standards. If there are deviations, further fine-tune the parameters.

[0030] Export the 3D model of the cylinder from the AutoCAD software as an STL format, and in the control software of the CLIP printer, select "Import Model" to find and load the 3D model of the cylinder in STL format.

[0031] In the software interface of the CLIP printer, set the corresponding printing parameters according to the specific characteristics (curing time, exposure intensity) of the used RPU 70 photosensitive resin. For example, for low-viscosity RPU 70 photosensitive resin, a short exposure time and low power may be required, while for high-viscosity RPU 70 photosensitive resin, the exposure time needs to be appropriately extended and the power increased. At the same time, find the "layer thickness" parameter in the control software of the CLIP printer and set the printing layer thickness (usually between 0.05 mm and 0.1 mm).

[0032] To prevent deformation and collapse during printing, select the appropriate support type (linear support, tree-like support) for the 3D model of the cylinder. For a cylinder, if the bottom is flat and directly contacts the building platform, no additional support is required. If there are overhanging parts, support needs to be added.

[0033] After all settings are correct, click "Start Printing". At this time, the CLIP printer will automatically deposit the photosensitive resin layer by layer onto the printing platform and use the continuous liquid interface production technology to achieve instant curing. During the printing process, monitor the working status of the printer to ensure that all components are running smoothly without jamming or abnormal noise. If any issues are found, pause the printing in a timely manner and troubleshoot the cause. When the printing is completed, carefully remove the printed cylinder to avoid damaging the delicate parts, and use an ultrasonic cleaner to clean the remaining uncured photosensitive resin. This continuous liquid interface production technology (CLIP) enables a fast and uniform curing process, greatly shortening the manufacturing cycle, making prototyping and small-batch production more efficient. At the same time, precise parameter settings and calibration ensure the high precision and excellent quality of the final product, meeting the manufacturing requirements of complex geometries and strict dimensional requirements. Meanwhile, by reasonably selecting the support type, it effectively avoids deformation and collapse problems that may occur during printing, ensuring the integrity and aesthetics of the product structure, simplifying the subsequent processing process, improving work efficiency, and providing a good foundation for subsequent surface treatment and applications.

[0034] S3. Calculate the curvature based on the geometric characteristics of the cylinder, calculate the vertices and inflection points of the cylinder according to the curvature, calculate the vertices and inflection points that the nozzle needs to pass through according to the non-planar path planning algorithm, and generate the movement trajectory of the UV-curing ink printer nozzle. Specifically: Based on the geometric characteristics (vertices and inflection points) of the cylinder, for each vertex, determine the neighborhood range. Using the method of a fixed radius, select all vertices within a certain distance from the current vertex as "neighbors". For example, according to the radius of the cylinder, then find other vertices whose distance from the current vertex is less than or equal to the radius. At the same time, calculate the angular change between the current vertex and all neighboring vertices, which can be achieved by calculating the included angle between the direction vectors of adjacent points. For example, vertex A has three neighboring vertices B, C, and D. Calculate the direction vectors of AB, AC, and AD according to the coordinates of A, B, C, and D respectively, and sum the products of the direction vectors of AB, AC, and AD to obtain the dot product of the vectors. The magnitude of the vector is the length and size of the vector, obtained by calculating the square root of the vector. Calculate the included angles between AB, AC, and AD using the dot product and magnitude of the AB, AC, and AD vectors, and take the average of all the calculated angular change values as the curvature of the vertex. And a high-curvature area means a greater average angular change.

[0035] Select the vertices and inflection points where the curvature of the cylinder changes significantly as the key points of the nozzle movement path. For example, place a vertex at regular intervals in the high-curvature area, while in the flat area, the intervals can be farther apart. These vertices and inflection points should be evenly distributed and cover the entire surface of the cylinder to ensure that the nozzle can completely cover all areas of the cylinder surface.

[0036] Use the tools in CAD software to extract the coordinates (x, z, y) of all vertices and inflection points of the cylinder and the normal vectors corresponding to the vertices. The normal vector refers to the vector perpendicular to a certain point on the surface of the cylinder, and for the curved surface of the cylinder, the normal vector changes with the position.

[0037] Input the coordinates (x, z, y) of all determined vertices and inflection points into the B-spline curve algorithm library. Ensure that the coordinates of each vertex and inflection point are accurately entered. Run the B-spline curve algorithm to generate a smooth movement trajectory of the UV-curing inkjet printer nozzle. The movement trajectory should cover the entire surface of the cylinder and maintain continuity and smoothness at the vertices and inflection points. During the movement of the nozzle along the predetermined trajectory, obtain the normal vector of the points passed by the nozzle along the trajectory in real time, which can be achieved by querying the extracted normal vectors. Calculate the angles and directions that the nozzle needs to adjust according to the normal vectors of the passed vertices and inflection points, so that the nozzle is always perpendicular to the surface of the cylinder, that is, the direction vector of the nozzle should be aligned with the normal vector of the current point, ensuring that the UV-curing inkjet printer nozzle can maintain the best posture during the entire printing process.

[0038] S4. Use the curing reaction kinetics mechanism to quantify the influence of temperature on the curing rate, set the inkjet parameters according to the curing rate, adjust the nozzle movement speed based on the curvature of the cylinder, and apply inkjet timing compensation at the edge area of the cylinder to offset the centrifugal offset. Specifically: Obtain the technical data sheet (TDS) of the UV-curing ink from the supplier, especially the activation energy and frequency factor. Based on the Arrhenius equation, use the known activation energy and frequency factor to calculate the curing rates at different temperatures within the expected working temperature range, expressed as: ; where represents the curing rate, represents the frequency factor, represents the activation energy, represents the temperature.

[0039] Create a table listing a series of historical working temperatures and their corresponding curing rates, with the working temperature range from 30°C to 60°C. Based on the historical temperature data of the inkjet environment in the table, use ANSYS simulation software and take the historical temperature data of the inkjet environment as input to predict the temperature change trend during the printing process. At the same time, take the predicted temperature change trend as input to further refine the predicted value of the curing rate. Meanwhile, based on the predicted value of the curing rate, establish a specific value for the target curing rate (such as 95%), and input this value into the control element as a reference standard. According to the predicted curing rate combined with the target curing rate, initially set the ejection frequency of the print head. Specifically, when the predicted curing rate is low (i.e., the curing speed is slow), a low ejection frequency should be selected so that each drop of ink has enough time to cure. On the contrary, the ejection frequency can be increased. Considering the influence of temperature change on the fluidity of the ink, set the inkjet pressure according to the working temperature range of the UV-curable ink printer (30°C to 60°C). Specifically, under high-temperature conditions exceeding 60°C, since the fluidity of the ink increases, the inkjet pressure can be reduced. Under low-temperature conditions below 30°C, increase the inkjet pressure to ensure sufficient ink volume. Combine the predicted curing rate and temperature to initially set the droplet volume output by the print head.

[0040] Under high-temperature conditions, using small-volume droplets helps to cure quickly and reduce sagging. While in a low-temperature environment, using large-volume droplets can help ensure the coating thickness and uniformity.

[0041] Establish a reference speed (such as moving at a speed of 10 millimeters per second), that is, the moving speed of the print head under ideal conditions (flat surface). At the same time, set an adjustment coefficient according to the influence degree of the cylinder curvature on the moving speed of the print head, and when the adjustment coefficient is 0.1, the printing effect and coating uniformity can be obtained.

[0042] Based on the cylinder curvature value, dynamically adjust the moving speed of the print head.

[0043] Specifically, for high-curvature areas, reduce the moving speed of the print head. On the contrary, in low-curvature areas, increase the moving speed of the print head, expressed as: ; Among them, represents the moving speed of the print head after dynamic adjustment, represents the adjustment coefficient, represents the curvature, represents the reference speed; Considering that when the print head of the UV-curable ink printer moves to the edge area of the cylinder (usually the part with large curvature change), due to the action of centrifugal force, effective and uniform spraying cannot be carried out on the edge area. The centrifugal force when the print head moves here for inkjet should be calculated according to the density of the ink, expressed as: ; wherein, represents the centrifugal force, represents the ink density, represents the moving speed of the nozzle, represents the radius of the cylinder; After calculating the centrifugal force, a compensation algorithm is constructed, and the compensation algorithm can automatically calculate the compensation time when the nozzle reaches the edge area. That is, input the position of the nozzle in the edge area, the moving speed of the nozzle, the radius of the cylinder, and the ink density into the compensation algorithm, which is expressed as: ; wherein, represents the compensation time, represents the centrifugal force, represents the ink density, represents the moving speed of the nozzle; Integrate the compensation algorithm into the control software of the UV-curable ink printer to ensure that the UV-curable ink printer can run in real time during inkjetting and adjust the jetting time when necessary.

[0044] S5. Inkjet the cylinder based on the nozzle movement trajectory, the moving speed of the nozzle, and the inkjet parameters. Specifically: Before inkjetting, ensure that the nozzle, the ink supply unit, and the control software of the UV-curable ink printer are in normal working conditions. Check whether the nozzle is blocked or damaged, and clean it. Use a micrometer to adjust the distance between the nozzle and the surface of the cylinder, usually kept between 0.5 mm and 2 mm. The specific value depends on the ink properties and printing requirements. At the same time, ensure that the nozzle is perpendicular to the surface of the cylinder to avoid uneven coating caused by angle deviation.

[0045] Import the optimized nozzle motion trajectory file (B-spline curve) generated by CAD software into the control software to ensure compatible file format and complete and error-free data. According to the pre-calculated jetting frequency, droplet size, and inkjet pressure, open the control software and enter the "Parameter Configuration" option. Locate the "Jetting Frequency" field and enter the jetting frequency value (the unit is usually Hz). For example, if you want to jet 10,000 drops per second, enter 10000. Then continue to find the "Droplet Size" option on the inkjet settings page and enter the appropriate droplet volume (usually in picoliters, pL). Return to find the "Inkjet Pressure" setting item and enter the nozzle pressure value (usually in kPa). The correct pressure is crucial to ensure smooth ink flow. Both too high and too low pressures will affect the printing quality. If you are not sure about the optimal pressure value, you can start from the standard value recommended by the manufacturer and then fine-tune according to the test results. At the same time, check whether the compensation algorithm integrated into the control software is complete. After completing all the necessary parameter settings, click the Apply button to make the changes take effect.

[0046] After completing all the preparations, start the UV-curing ink printer. The nozzles of the UV-curing ink printer move according to the preset motion trajectory and speed. When the nozzle reaches the specified position, release the ink according to the set jetting frequency. At this time, monitor the speed and jetting synchronization of the nozzle to ensure that each jet can accurately land on the surface of the cylinder. After inkjetting, place the cylinder sprayed with ink under the UV light source of the UV-curing ink printer to ensure that the entire area to be cured can receive uniform UV light irradiation. For some cylinders with complex shapes and large volumes, it is necessary to irradiate in segments and rotate the cylinder to ensure that all coatings can be fully cured. After irradiation, turn off the UV light source and wait for a moment for the cylinder to cool to room temperature. Check whether the ink layer is completely cured and perform further local supplementary irradiation if necessary.

[0047] S6. After completion, use a laser scanner to obtain the three-dimensional topography of the cylinder surface and identify the uneven inkjet areas using the K-means clustering algorithm. Specifically: Use a high-precision rotating platform to ensure that the rotating platform can stably support and accurately align the cylinder. Place the ink-jet printed cylinder on the rotating platform and use adjustment screws to align the central axis of the cylinder with the central axis of the rotating platform. Before installing the LMS single-line laser scanner, check whether the LMS single-line laser scanner, accessories, brackets and cables are complete, and confirm that the device has no physical damage. Ensure that the working environment is clean and tidy to avoid dust or other impurities affecting the scanning results. In addition, ensure that there is enough space to place the rotating platform and the scanner so that the scanner can freely adjust its angle and position. According to the size and shape of the cylinder, select a suitable position to install the bracket. Usually, the bracket should be placed on one side of the cylinder so that the laser beam can vertically irradiate the surface of the cylinder. Use the provided screws to firmly fix the bracket on the rotating platform to ensure that the bracket is stable and will not move due to external vibration. Connect the laser scanner to the power adapter and connect it to the computer via an Ethernet cable. Ensure that there is no looseness during the connection process. At the same time, install the laser scanner on the pre-set bracket and manually adjust the angle and height of the LMS single-line laser scanner until the laser beam can cover the entire surface of the cylinder. Use the built-in calibration function to ensure that the scanner is in the optimal position. For the cylinder, special attention should be paid to adjusting the laser beam so that the laser beam is parallel to the axis of the cylinder and maintains a constant distance from the surface of the cylinder (for example, 10 cm). After the adjustment is completed, start the LMS single-line laser scanner and start recording the data reflected from the surface of the cylinder. Pay attention to observing whether the data is normal without omission and abnormal data. Continuously monitor the entire scanning process to ensure that the speed of the rotating platform and the working state of the laser scanner are stable. If any problems are found, stop immediately and check the device settings.

[0048] After collecting the scanning data of the LMS single-line laser scanner, import the scanning data into Python in the computer for processing. Use specific software tools (such as the method based on triangulation) to convert the discrete data points into a continuous three-dimensional surface to generate the surface model of the cylinder. Calculate the average height of the cylinder surface based on all data points and design an ink-jet uniformity threshold (for example, 0.05 mm) according to the average height of the cylinder surface.

[0049] Before executing the K-means clustering algorithm using the computer Python, the elbow method is used to determine the optimal number of clusters (k value). Specifically, using the elbow method involves plotting the total squared error for different k values, finding the "elbow" position as the optimal k value, inputting the k value into the K-means clustering algorithm and setting the number of iterations (50 times). After executing the K-means clustering algorithm, each data point will be assigned to a cluster, and a three-dimensional graphing tool is used to view the position and distribution of each cluster. For each cluster, all the data point heights belonging to the cluster are extracted, the standard deviation of the heights is calculated in Python, and the standard deviation of the heights of each cluster is compared with a pre-set inkjet uniformity threshold to find the clusters where the standard deviation of the heights exceeds the pre-set inkjet uniformity threshold. The clusters represent areas of non-uniform inkjet, and at the same time, the coordinates of the non-uniform inkjet areas are marked. The K-means clustering implementation method can efficiently and accurately identify the specific locations of non-uniform inkjet, providing a detailed report for guiding subsequent repairs and process adjustments. This precise problem positioning not only reduces unnecessary rework but also improves production efficiency.

[0050] S7. Perform directional correction on the non-uniform inkjet area using local light-curing overcoating, specifically: Open the path planning software SolidWorks, import the 3D model of the cylinder and the marked non-uniform inkjet area and measure the area of the non-uniform inkjet area. Use the B-spline curve algorithm again to generate a new overcoating path in combination with the coordinates of the non-uniform inkjet area, ensuring that the new path covers all non-uniform areas and minimizing unnecessary movement to improve efficiency. Import the original nozzle path file, compare and adjust it with the newly generated overcoating path to ensure compatibility, and at the same time save the final overcoating path file. Determine the required coating thickness for each overcoating area according to the product specifications, which is consistent with the previously sprayed standard thickness, and adjust the inkjet parameters again according to the area of the non-uniform inkjet area and the required coating thickness, which can avoid overspraying and underspraying. Import the overcoating path, the area of the non-uniform inkjet area, and the adjusted inkjet parameters into the UV-curing inkjet printer control software.

[0051] Move the UV-curing ink printer nozzle above the area that needs to be retouched. Adjust the distance between the nozzle and the surface of the cylinder to be between (for example, 0.5 mm to 2 mm). Start the UV-curing ink printer for re-spraying, ensuring that the nozzle maintains a stable speed and consistent pressure throughout the process to guarantee the quality of the newly sprayed coating. After spraying each retouched area, immediately start the UV light source to irradiate the newly sprayed ink to quickly cure the ink. After curing is completed, prepare a suitable handheld thickness gauge, which must be a model suitable for measuring the coating thickness on the surface of the cylinder, and ensure that the accuracy of the handheld thickness gauge meets the requirements. To ensure that the measurement results are representative, select multiple evenly distributed points in the uneven inkjet area of the cylinder for measurement. Gently place the handheld thickness gauge on the selected measurement points, ensuring that the measuring head is in perpendicular contact with the surface of the cylinder to avoid errors caused by tilting, and record the thickness values of each measurement point. For each measurement point, the measurement can be repeated several times and the average value can be taken to improve the accuracy of the data. This local light-curing retouching can ensure the seamless docking of the new and old coatings while ensuring the consistency and uniformity of the coating on the entire surface of the cylinder, which is particularly important for products that require high standards of appearance and performance.

[0052] This embodiment also provides a computer device applicable to the situation of using the method for adjusting the inkjet uniformity of the light-curing 3D printing of a cylinder, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the method for adjusting the inkjet uniformity of the light-curing 3D printing of a cylinder as proposed in the above embodiment.

[0053] This computer device can be a terminal. This computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of this computer device is used to provide computing and control capabilities. The memory of this computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of this computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a carrier network, NFC (Near Field Communication), or other technologies. The display screen of this computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of this computer device can be a touch layer covering the display screen, or a button, a trackball, or a touchpad provided on the housing of the computer device, or an external keyboard, a touchpad, or a mouse, etc.

[0054] This embodiment also provides a storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the method for adjusting the inkjet uniformity of stereolithography 3D printing using a cylinder as described in the above embodiment. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM for short), electrically erasable programmable read-only memory (EEPROM for short), erasable programmable read-only memory (EPROM for short), programmable read-only memory (PROM for short), read-only memory (ROM for short), magnetic memory, flash memory, a magnetic disk, or an optical disc.

[0055] In summary, the present invention: uses a non-planar path planning algorithm to calculate the curvature according to the geometric characteristics of the cylinder and generate the nozzle movement trajectory, effectively solving the problem of uneven inkjet caused by uneven surfaces. At the same time, by combining the curing reaction kinetics mechanism to quantify the influence of temperature on the curing rate, the curing efficiency and coating thickness control are optimized, ensuring the stability of the finished product quality. After the initial printing is completed, the K-means clustering algorithm is used to identify the uneven inkjet areas and perform local stereolithography supplementary coating for directional correction, reducing the workload of manual inspection, greatly improving the detection accuracy and production efficiency. The organic combination of these innovative technologies not only solves the problem of uneven inkjet encountered in traditional 3D printing, but also greatly improves the surface consistency and aesthetics of the product, reduces resource waste, and improves the overall production efficiency.

[0056] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for adjusting inkjet uniformity in light-curing 3D printing using a cylinder, characterized in that: include, Use CAD software to import the 3D model of the target cylinder and select a photosensitive resin that is compatible with the 3D printer; Loading the photosensitive resin into the 3D printer, and printing and curing the cylindrical 3D model to obtain a cylindrical body; The curvature is calculated based on the geometric features of the cylinder, the vertices and inflection points of the cylinder are calculated based on the curvature, and the vertices and inflection points that the nozzle needs to pass through are calculated based on the non-planar path planning algorithm to generate the motion trajectory of the UV curing ink printer nozzle; Use the curing reaction kinetics mechanism to quantify the effect of temperature on the curing rate, set the inkjet parameters according to the curing rate, adjust the nozzle movement speed based on the curvature of the cylinder, and apply inkjet timing compensation at the edge of the cylinder to offset the centrifugal deviation; The cylinder is inkjetted based on the nozzle motion trajectory, nozzle motion speed and inkjet parameters. After completion, a laser scanner is used to obtain the three-dimensional morphology of the cylinder surface and the K-means clustering algorithm is used to identify the uneven inkjet area. Local photocuring re-coating is used to perform directional correction on the uneven inkjet area.

2. The method for adjusting inkjet uniformity of light-cured 3D printing using a cylinder as claimed in claim 1, characterized in that: The CAD software is used to import the target cylindrical three-dimensional model, and a photosensitive resin suitable for the 3D printer is selected, specifically: Use AutoCAD software to import the 3D model of the target cylinder and convert the 3D model of the cylinder into STL format; Import the cylindrical 3D model in STL format into the 3D printer CLIP; Select photosensitive resin that meets the CLIP requirements of the 3D printer as the printing material.

3. The method for adjusting inkjet uniformity of light-cured 3D printing using a cylinder as claimed in claim 2, characterized in that: The photosensitive resin is loaded into the 3D printer, and the cylinder is printed and cured according to the three-dimensional model of the cylinder to obtain the cylinder, specifically: Load the photosensitive resin into the 3D printer CLIP and perform preliminary calibration; Start the 3D printer CLIP to print the cylinder and perform simultaneous printing and curing with photosensitive resin.

4. The method for adjusting inkjet uniformity of light-cured 3D printing using a cylinder as claimed in claim 3, characterized in that: The curvature is calculated according to the geometric features of the cylinder, the vertices and inflection points of the cylinder are calculated according to the curvature, and the vertices and inflection points that the nozzle needs to pass through are calculated according to the non-planar path planning algorithm to generate the motion trajectory of the UV curing ink printer nozzle, specifically: Use the vertex in the cylinder geometry to calculate the angle change with all neighboring vertices, and take the average value as the cylinder curvature; According to the vertices and inflection points of the cylinder, the B-spline curve path planning algorithm is used to calculate the vertices and inflection points that the nozzle needs to pass through, and the vertices and inflection points are connected to form the movement trajectory of the nozzle, and the nozzle is always perpendicular to the normal direction of the cylinder surface.

5. The method for adjusting inkjet uniformity of light-cured 3D printing using a cylinder as claimed in claim 4, characterized in that: The curing reaction kinetics mechanism is used to quantify the effect of temperature on the curing rate, the inkjet parameters are set according to the curing rate, the nozzle movement speed is adjusted based on the curvature of the cylinder, and the inkjet timing compensation is applied to the edge area of ​​the cylinder to offset the centrifugal deviation, specifically: Based on the chemical composition of UV curable ink and its curing behavior at different temperatures, the Arrhenius equation is used to quantify the effect of temperature on the curing rate and set the inkjet parameters; The movement speed of the nozzle is adjusted based on the curvature of the cylinder, and the inkjet compensation time is calculated using a compensation algorithm based on the centrifugal force of the nozzle in the edge area of ​​the cylinder.

6. The method for adjusting inkjet uniformity of light-cured 3D printing using a cylinder as claimed in claim 5, characterized in that: The inkjet printing on the cylinder based on the nozzle motion trajectory, nozzle motion speed and inkjet parameters is specifically as follows: Adjust the distance between the nozzle of the UV curing ink printer and the surface of the cylinder, and input the nozzle movement trajectory, nozzle movement speed and inkjet parameters into the control software of the UV curing ink printer and set the parameters; Start the UV curing ink printer to spray ink on the cylinder, and monitor the working status of the nozzle in real time during the ink spraying process; After the inkjet process is complete, the cylinder is placed under a UV light source for curing.

7. The method for adjusting inkjet uniformity of light-cured 3D printing using a cylinder as claimed in claim 6, characterized in that: After the completion, a laser scanner is used to obtain the three-dimensional morphology of the cylinder surface and a K-means clustering algorithm is used to identify the inkjet uneven area, specifically: The cylinder is fixed on a rotating platform and a laser scanner is used to perform a full scan and record the data points of laser reflection in real time; The height difference of each data point is calculated and mapped to the corresponding coordinate system. The K-means clustering algorithm is used to calculate the degree of deviation of all data points in the coordinate area relative to the average height to identify the uneven inkjet area.

8. The method for adjusting inkjet uniformity of light-cured 3D printing using a cylinder as claimed in claim 7, characterized in that: The method of using local photocuring to correct the uneven inkjet area is as follows: The original nozzle path is modified based on the coordinates of the uneven inkjet area to obtain a re-coating path; Readjust the nozzle parameters according to the size of the recoating area and the required coating thickness; Use a UV curing ink printer to re-spray the touch-up area, and after completing the spraying of each touch-up area, immediately start the UV light source to irradiate the newly sprayed ink to quickly cure the ink.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for adjusting inkjet uniformity of photocuring 3D printing using a cylinder as described in any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for adjusting inkjet uniformity of photocuring 3D printing using a cylinder as described in any one of claims 1 to 8 are implemented.

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