A method for adjusting the inkjet uniformity of stereolithography 3D printing using a cylinder

Abstract

The present invention discloses a method for adjusting the inkjet uniformity of light-curing 3D printing using a cylinder, which relates to the technical field of inkjet uniformity adjustment. The method includes 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, generating the movement trajectory of the UV-curing inkjet printer nozzle, setting the inkjet parameters according to the curing rate, adjusting the nozzle movement speed based on the cylinder curvature, applying inkjet timing compensation in the edge area of the cylinder to offset the centrifugal offset, performing inkjet on the cylinder based on the nozzle movement trajectory, nozzle movement speed and inkjet parameters, and identifying the uneven inkjet area using the K-means clustering algorithm. The present invention solves the technical problem of uneven inkjet encountered in the 3D printing process through the non-planar path planning algorithm, and improves the quality and production efficiency of the final product.

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. Ultimately, the improvement of product surface consistency and aesthetics 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 change on the curing rate of UV-curing ink 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:

[0007] In a 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 compatible with the 3D printer;

[0008] 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;

[0009] 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;

[0010] Using the curing reaction kinetics mechanism to quantify the influence of temperature on the curing rate, setting the inkjet parameters, and at the same time adjusting the nozzle movement speed to apply inkjet timing compensation at the edge area of the cylinder to offset the centrifugal offset;

[0011] Based on the nozzle movement trajectory, nozzle movement speed, and inkjet parameters, inkjet printing is performed on the cylinder. After completion, a 3D scanner is used to obtain the three-dimensional surface topography of the cylinder, and the K-means clustering algorithm is used to identify the uneven inkjet areas. Local photocuring is used to perform directional correction on the uneven inkjet areas.

[0012] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing of cylinders according to the present invention, specifically: The 3D model of the target cylinder is imported using CAD software, and a photosensitive resin compatible with the 3D printer is selected, specifically:

[0013] The 3D model of the target cylinder is imported using AutoCAD software, and the 3D model of the cylinder is converted into the STL format;

[0014] The 3D model of the cylinder in the STL format is imported into the 3D printer CLIP;

[0015] A photosensitive resin meeting the requirements of the 3D printer CLIP is selected as the printing material.

[0016] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing of cylinders according to the present invention, specifically: The photosensitive resin is loaded into the 3D printer, and the cylinder is printed and cured according to the 3D model of the cylinder, specifically:

[0017] The photosensitive resin is loaded into the 3D printer CLIP and preliminary calibration is performed;

[0018] The 3D printer CLIP is started to print the cylinder, and synchronous printing and curing are performed using the photosensitive resin.

[0019] As a preferred embodiment of the method for adjusting the inkjet uniformity of photocuring 3D printing of cylinders according to the present invention, specifically: 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 according to the non-planar path planning algorithm, and the movement trajectory of the UV-curing inkjet printer nozzle is generated, specifically:

[0020] The angle change between all adjacent vertices is calculated using the vertices in the geometric features of the cylinder, and the average value is taken as the curvature of the cylinder;

[0021] Based on 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. At the same time, the vertices and inflection points are connected to form the nozzle movement trajectory, and the nozzle is always perpendicular to the normal direction of the cylinder surface.

[0022] As a preferred embodiment of the method for adjusting the inkjet uniformity in the photocuring 3D printing using a cylinder according to the present invention, the following steps are included: quantifying the influence of temperature on the curing rate using the curing reaction kinetics mechanism, setting the inkjet parameters according to the curing rate, adjusting the nozzle movement speed based on the curvature of the cylinder, and applying an inkjet timing compensation in the edge area of the cylinder to offset the centrifugal deviation. Specifically:

[0023] According to the chemical composition of the UV-curable ink and its curing behavior at different temperatures, use the Arrhenius equation to quantify the influence of temperature on the curing rate and set the inkjet parameters;

[0024] 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.

[0025] As a preferred embodiment of the method for adjusting the inkjet uniformity in the photocuring 3D printing using a cylinder according to the present invention, the following steps are included: inkjetting on the cylinder based on the nozzle movement trajectory, nozzle movement speed, and inkjet parameters. Specifically:

[0026] 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;

[0027] Start the UV-curable ink printer for inkjetting on the cylinder, and at the same time, monitor the working state of the nozzle in real time during the inkjetting process;

[0028] After the inkjetting is completed, place the cylinder under the UV light source for curing.

[0029] As a preferred embodiment of the method for adjusting the inkjet uniformity in the photocuring 3D printing using a cylinder according to the present invention, the following steps are included: after completion, use a laser scanner to obtain the three-dimensional topography of the cylinder surface and identify the non-uniform inkjet areas using the K-means clustering algorithm. Specifically:

[0030] Fix the cylinder on a rotating platform, and use a laser scanner to perform a comprehensive scan to record the laser reflection data points in real time;

[0031] 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 non-uniform inkjet areas.

[0032] As a preferred embodiment of the method for adjusting the inkjet uniformity in the photocuring 3D printing using a cylinder according to the present invention, the following steps are included: using local photocuring repainting for directional correction of the non-uniform inkjet areas. Specifically:

[0033] Modify the original nozzle path based on the coordinates of the non-uniform inkjet area to obtain a supplementary coating path;

[0034] Readjust the nozzle parameters according to the area size of the supplementary coating area and the required coating thickness;

[0035] Use a UV-curing ink printer to re-spray within the supplementary coating area, and immediately start the UV light source to irradiate the newly sprayed ink after completing the spraying of each supplementary coating area, so that the ink cures quickly.

[0036] 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 light-curing 3D printing using a cylinder as described in the first aspect of the present invention is implemented.

[0037] 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 light-curing 3D printing using a cylinder as described in the first aspect of the present invention is implemented.

[0038] 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 surface unevenness 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 non-uniform inkjet area is identified by the K-means clustering algorithm, and local light-curing supplementary coating is carried out 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 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. Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for description in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 It is a flowchart of the method for adjusting the inkjet uniformity of light-curing 3D printing using a cylinder.

[0041] Figure 2 It is a schematic diagram of the parameter adjustment mechanism.

[0042] Figure 3 It is a schematic diagram of the device structure.

[0043] Figure 4 It is a schematic diagram for detection and correction. Specific Embodiments

[0044] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings of the specification.

[0045] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0046] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that mutually excludes other embodiments.

[0047] Refer to Figures 1 to 4 , which is an embodiment of the present invention. This embodiment provides a method for adjusting the uniformity of inkjet printing in light-curing 3D printing using a cylinder, including the following steps:

[0048] S1. Import the three-dimensional model of the cylinder through CAD software and select the photosensitive resin suitable for the 3D printer CLIP. Specifically:

[0049] 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, such as the height exceeding and being lower than the target, and the inaccurate diameter, correct the three-dimensional model of the cylinder through stretching and scaling in the AutoCAD software.

[0050] 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.

[0051] S2. Load the photosensitive resin into the CLIP printer and print and cure according to the three-dimensional model of the cylinder to obtain the cylinder. Specifically:

[0052] Prepare the determined RPU70 photosensitive resin and confirm that the storage conditions (temperature, light protection) of the RPU70 photosensitive resin meet the requirements to ensure performance.

[0053] Turn on the power of the CLIP printer to start and enter the main interface. Select the "Maintenance" option on the main interface, run the self-check, and check whether all mechanical components, the printing platform, the projection module, and the 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.

[0054] 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 trial printing to verify whether the printing accuracy and quality meet the expected standards. If there are deviations, further fine-tune the parameters.

[0055] Export the 3D model of the cylinder from the AutoCAD software to the 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 the STL format.

[0056] 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 0.05mm and 0.1mm).

[0057] To prevent deformation and collapse during printing, select the appropriate support type (linear support, tree 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.

[0058] 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 causes. 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. Also, by reasonably selecting the support type, it effectively avoids possible deformation and collapse problems 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.

[0059] 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:

[0060] 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 dot products of AB, AC, and AD vectors after multiplication. The modulus of a vector refers to the length and magnitude of the vector, which is obtained by calculating the square root of the vector. Calculate the included angles between AB, AC, and AD using the dot product and modulus 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 region means a greater average angular change.

[0061] Select the vertices and inflection points with obvious curvature changes on the cylinder as the key points of the nozzle movement path. For example, place a vertex at regular intervals in the high-curvature region, while in the flat region, 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.

[0062] 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 vector 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 cylinder surface, the normal vector changes with the position.

[0063] 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 ink 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 ink printer nozzle can maintain the best posture during the entire printing process.

[0064] 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 cylinder curvature, and apply inkjet timing compensation at the edge area of the cylinder to offset the centrifugal offset, specifically:

[0065] 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:

[0066] ;

[0067] where represents the curing rate, represents the frequency factor, represents the activation energy, represents the temperature.

[0068] 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. Also, 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 nozzle. 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 nozzle.

[0069] 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.

[0070] Establish a reference speed (such as moving at a speed of 10 millimeters per second), that is, the movement speed of the nozzle under ideal conditions (flat surface). At the same time, set an adjustment coefficient according to the influence degree of the cylinder curvature on the nozzle movement speed, and when the adjustment coefficient is 0.1, the printing effect and coating uniformity can be obtained.

[0071] Based on the cylinder curvature value, dynamically adjust the movement speed of the nozzle.

[0072] Specifically, for high-curvature areas, reduce the movement speed of the nozzle. On the contrary, in low-curvature areas, increase the movement speed of the nozzle, expressed as:

[0073] ;

[0074] Where, represents the movement speed of the nozzle after dynamic adjustment, represents the adjustment coefficient, represents the curvature, represents the reference speed;

[0075] When the print head of a UV-curable inkjet printer moves to the edge area of a cylinder (usually the part with a 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 inkjetting should be calculated according to the density of the ink, which is expressed as:

[0076] ;

[0077] Among them, represents the centrifugal force, represents the ink density, represents the movement speed of the print head, represents the radius of the cylinder;

[0078] After calculating the centrifugal force, a compensation algorithm is constructed. The compensation algorithm can calculate the compensation time by itself when the print head reaches the edge area. That is, the position of the edge area where the print head is located, the movement speed of the print head, the radius of the cylinder and the ink density are input into the compensation algorithm, which is expressed as:

[0079] ;

[0080] Among them, represents the compensation time, represents the centrifugal force, represents the ink density, represents the movement speed of the print head;

[0081] Integrate the compensation algorithm into the control software of the UV-curable inkjet printer to ensure that the UV-curable inkjet printer can run in real time during inkjetting and adjust the spraying time when necessary.

[0082] S5. Inkjet the cylinder based on the movement trajectory of the print head, the movement speed of the print head and the inkjet parameters. Specifically:

[0083] Before inkjetting, ensure that the print head, ink supply unit and control software of the UV-curable inkjet printer are in normal working condition. Check whether the print head is blocked or damaged, and clean it. Use a micrometer to adjust the distance between the print head and the surface of the cylinder, usually keeping it between 0.5 mm and 2 mm. The specific value depends on the ink characteristics and printing requirements. At the same time, ensure that the print head is perpendicular to the surface of the cylinder to avoid uneven coating caused by angle deviation.

[0084] Import the optimized nozzle motion trajectory file (B-spline curve) generated by CAD software into the control software, ensuring that the file format is compatible and the data is complete and error-free. 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 (usually in Hz). For example, if you want to jet 10,000 drops per second, enter 10000. Continue to find the "Droplet Size" option on the inkjet settings page and enter the appropriate droplet volume (usually in picoliters, pL). Then, return to find the "Inkjet Pressure" setting item and enter the nozzle pressure value (usually in kPa). The correct pressure is crucial for ensuring 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 with 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 effective.

[0085] After completing all the preparations, start the UV-curing ink printer. The nozzles of the UV-curing ink printer move along the preset motion trajectory and speed. When the nozzle reaches the specified position, it releases ink according to the set jetting frequency. At this time, monitor the speed and jetting synchronization of the nozzle to ensure that each jetting can accurately land on the surface of the cylinder. After inkjetting, place the cylinder coated with ink under the UV light source of the UV-curing ink printer to ensure that the entire area to be cured can be evenly irradiated by the UV light source. 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, if necessary, perform further local supplementary irradiation.

[0086] S6. 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 uneven inkjet areas. Specifically:

[0087] Use a high-precision rotating platform to ensure that the rotating platform can stably support and accurately align the cylinder. Place the cylinder that has been inkjet-printed on the rotating platform, and use the 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 and its 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, 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.

[0088] 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 the data points, and design an inkjet uniformity threshold (for example, 0.05 mm) according to the average height of the cylinder surface.

[0089] Before executing the K-means clustering algorithm using the Python programming language, the elbow method is used to determine the optimal number of clusters (the value of k). Specifically, using the elbow method involves plotting the total squared error for different values of k, finding the "elbow" position as the optimal value of k, inputting the value of k 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. A three-dimensional graphing tool is used to view the position and distribution of each cluster. For each cluster, the heights of all data points belonging to the cluster are extracted, and the standard deviation of the heights is calculated in Python. The standard deviation of the heights for each cluster is compared with a pre-set inkjet uniformity threshold, and clusters with a standard deviation of heights exceeding the pre-set inkjet uniformity threshold are identified. These clusters represent areas of non-uniform inkjetting, and at the same time, the coordinates of the areas of non-uniform inkjetting are marked. The implementation method of the K-means clustering can efficiently and accurately identify the specific locations of non-uniform inkjetting, 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.

[0090] S7. Locally cure and recoat the non-uniform inkjetting areas for directional correction, specifically:

[0091] Open the path planning software SolidWorks, import the three-dimensional model of the cylinder and the marked non-uniform inkjetting areas, and measure the area of the non-uniform inkjetting areas. Use the B-spline curve algorithm again to generate a new recoating path in combination with the coordinates of the non-uniform inkjetting areas, 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 recoating path to ensure compatibility, and at the same time save the final recoating path file. Determine the required coating thickness for each recoating area according to the product specification requirements, keeping it consistent with the previously sprayed standard thickness. Adjust the inkjet parameters again based on the area of the non-uniform inkjetting areas and the required coating thickness, which can avoid overspraying and underspraying. Import the recoating path, the area of the non-uniform inkjetting areas, and the adjusted inkjet parameters into the UV-curing inkjet printer control software.

[0092] Move the UV-curing ink printer nozzle above the area that needs to be re-coated. 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 re-coated 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 re-coating 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-standard appearance and performance.

[0093] 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.

[0094] The computer device can be a terminal. The 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 the computer device is used to provide computing and control capabilities. The memory of the 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 the 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 the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the 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.

[0095] 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.

[0096] In summary, in the present invention: the non-planar path planning algorithm is adopted 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, the influence of temperature on the curing rate is quantified in combination with the curing reaction kinetics mechanism, optimizing the curing efficiency and coating thickness control, 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 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 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.

[0097] 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 by the scope of the claims of the present invention.

Claims

1. A method for adjusting the inkjet uniformity of stereolithography 3D printing using a cylinder, characterized in that: including Import the 3D model of the target cylinder using CAD software and select the photosensitive resin compatible with the 3D printer; Load the photosensitive resin into the 3D printer and print and cure it according to the 3D model of the cylinder to obtain a cylinder; Calculate the angle change between the vertex in the geometric features of the cylinder and all adjacent vertices 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; 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 cylinder curvature, 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; Perform inkjet on the cylinder based on the nozzle movement trajectory, nozzle movement speed and inkjet parameters. After completion, use a laser scanner to obtain the three-dimensional surface topography of the cylinder and use the K-means clustering algorithm to identify the uneven inkjet area, and use local light curing and coating to perform directional correction on the uneven inkjet area.

2. The method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder according to claim 1, wherein: The step of importing the 3D model of the target cylinder using CAD software and selecting the photosensitive resin compatible with the 3D printer is specifically as follows: 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 3D model of the cylinder in STL format into the 3D printer CLIP; Select the photosensitive resin that meets the requirements of the 3D printer CLIP as the printing material.

3. The method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder according to claim 2, characterized in that: The step of loading the photosensitive resin into the 3D printer and printing and curing it according to the 3D model of the cylinder is specifically as follows: 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.

4. The method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder according to claim 3, characterized in that: The step of performing inkjet 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 cylinder surface, and input the nozzle movement trajectory, nozzle movement speed and inkjet parameters into the control software of the UV-curable ink printer and perform parameter settings; Start the UV-curable ink printer to perform inkjet on the cylinder, and at the same time monitor the working state of the nozzle in real time during the inkjet process; After the inkjet is completed, place the cylinder under the UV light source for curing.

5. The method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder according to claim 4, characterized in that: The step of using a laser scanner to obtain the three-dimensional surface topography of the cylinder and using the K-means clustering algorithm to identify the uneven inkjet area after completion is specifically as follows: Fix the cylinder on the rotating platform and use a laser scanner to perform a comprehensive scan to record the laser reflection data points 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 uneven inkjet area.

6. The method for adjusting the inkjet uniformity of photocuring 3D printing using a cylinder according to claim 5, characterized in that: The step of using local light curing and coating to perform directional correction on the uneven inkjet area is specifically as follows: Modify the original nozzle path based on the coordinates of the non-uniform inkjet area to obtain a supplementary coating path; Readjust the nozzle parameters according to the area size of the supplementary coating area and the required coating thickness; Use a UV-curing ink printer to spray again within the supplementary coating area, and immediately start the UV light source to irradiate the newly sprayed ink after completing the spraying of each supplementary coating area, so that the ink cures quickly.

7. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that: When the processor executes the computer program, the steps of the method for adjusting the inkjet uniformity of the light-curing 3D printing using a cylinder according to any one of claims 1 to 6 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, the steps of the method for adjusting the inkjet uniformity of the light-curing 3D printing using a cylinder according to any one of claims 1 to 6 are implemented.

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