A method for FDM customized color printing based on multi-color filament proportioning

Abstract

The application relates to a FDM customized color printing method based on multi-color filament proportioning, which comprises the following steps: establishing a color 3D model of a color workpiece to be printed; automatically planning a printing strategy and generating a continuous color conversion filament model matched with the printing strategy; determining a plurality of color segments based on the continuous color conversion filament model and extracting color requirements and length parameters of each color segment; calculating the number proportion of N single-color filaments in each color segment according to the color requirements of each color segment by using a multi-color filament proportioning calculation method to prepare a color core filament; and using transparent strips to spiral wrap, bind and fix the color core filament to prepare a customized color printing consumable, printing is completed according to the printing strategy, and a color workpiece is obtained. The application prepares a customized color printing consumable by pre-proportioning multi-color single-color filaments, full-color printing can be realized only by using a single-nozzle FDM printer, and the equipment threshold and cost of color FDM printing are greatly reduced.

Description

Technical Field

[0001] This application relates to the field of fused deposition modeling 3D printing, and more specifically, to a customized color printing method for FDM based on multicolor filament ratios. Background Technology

[0002] Fused Deposition Modeling (FDM) technology, as one of the mainstream technologies in the 3D printing field, has been widely used in amateur creation, education, product design, industrial parts manufacturing, and cultural and creative industries due to its advantages of low equipment cost, simple operation, and diverse material selection. With the upgrading of application needs in various fields, the requirements for the refinement and personalization of FDM color printing are increasing. Color printing can not only intuitively display the appearance of products and realize personalized designs, but also distinguish the functions of parts through color markings.

[0003] Current methods for achieving FDM color printing still have many shortcomings. Traditional FDM printing consumables are mostly monochrome filaments. Achieving color printing mainly relies on solutions such as multi-head filament changing printing, single-head automatic filament changing printing, real-time nozzle color mixing, and post-printing inkjet coloring. Multi-head filament changing printing equipment has a complex structure, high risk of nozzle interference, high purchase and maintenance costs, and a cumbersome filament changing process that is prone to clogging, filament pulling, and printing interruption. It is also difficult to achieve continuous and smooth color transitions. Single-head filament changing printing requires frequent filament unloading, feeding, and wiping operations, resulting in large amounts of waste, low printing efficiency, and slow color switching response, which cannot meet the requirements of high-precision and high-efficiency color printing. Although real-time nozzle color mixing can achieve gradient effects, the color mixing uniformity is poor, the color control precision is low, and it is prone to color bleeding, color deviation, and blurred transitions, making it difficult to stably reproduce the true colors of the model. Post-printing inkjet coloring is a post-processing technology with weak color adhesion, easy wear and peeling, and inability to achieve coloring inside the model and between layers. The color reproduction of fine textures and complex structures is extremely poor.

[0004] Existing color composite 3D printing consumables either suffer from uneven melting and mixing due to unreasonable structural design, resulting in low color reproduction; or they focus only on color realization while neglecting the functional composite of materials, failing to endow printed workpieces with differentiated mechanical, temperature resistance, and other properties; at the same time, some color composite consumables have limited color control dimensions, making it difficult to achieve precise segmented color changes and stable molding of gradient colors, thus limiting the application scenarios and development space of FDM color printing. Summary of the Invention

[0005] To overcome at least one deficiency in the prior art, this application provides a customized FDM color printing method based on the ratio of multi-color filaments.

[0006] Firstly, a customized FDM color printing method based on multi-color filament ratios is provided, including: Create a color 3D model of the workpiece to be printed, divide the color 3D model into continuous two-dimensional slices, and obtain the slice information, including the slice size, position, outline boundary and outer outline color. Based on the slice information, the printing strategy is automatically planned, and a continuous color-changing filament model matching the printing strategy is generated. Based on the continuous color change filament model, multiple color segments are determined, and the color requirements and length parameters of each color segment are extracted. According to the color requirements of each color segment, a multi-color filament ratio calculation method is used to calculate the ratio of the number of N single-color filaments in each color segment. Based on the ratio of the number of N monochrome filaments in each color segment and the length parameters of the corresponding color segment, colored core filaments are prepared; transparent strips are used to spirally wrap and bind the colored core filaments to prepare customized color printing consumables. Set the printing parameters of the FDM printer, feed the customized color printing consumables into the printhead of the FDM printer, and complete the printing according to the printing strategy to obtain a color workpiece.

[0007] In one embodiment, the printing path in the printing strategy is a composite scanning path biased from the outside to the inside. The outer contour area of ​​the scanning path is printed with precise color separation, which corresponds one-to-one with the color segments of the continuous color change filament model. The inner filling area of ​​the scanning path is filled with any color.

[0008] In one embodiment, multiple color segments are all formal color segments, and a transition color segment is added at each color switching node of the continuous color transformation filament model.

[0009] In one embodiment, the length of the transition color segment is calculated using the following formula:

[0010]

[0011] in, The length of the transition color segment, This refers to the evacuation volume of the molten chamber in the FDM printer nozzle. To customize the cross-sectional area of ​​color printing consumables, For color contrast safety factor, The inner diameter of the nozzle's thermal break zone. The length of the thermal break zone, The length of the nozzle conical cavity. This refers to the nozzle outlet orifice diameter.

[0012] In one embodiment, the color arrangement of the continuous color-changing filament model is synchronously matched with the outer contour printing sequence, printing speed, and layer thickness parameters of the printing strategy.

[0013] In one embodiment, a multi-color filament ratio calculation method is used to calculate the ratio of the number of N single-color filaments within each color segment, based on the color requirements of each color segment, including: Calculate the total number of monochromatic filaments (m) that can be accommodated within the cross-section of a single customized consumable; The RGB values ​​of the base colors of the N monochrome filaments are converted to CMYK values ​​to obtain the base color CMYK matrix; the RGB color values ​​of the target color segments are converted to CMYK values ​​to obtain the target color CMYK vector; based on the base color CMYK matrix and the target color CMYK vector, the initial weights of the N monochrome filaments are obtained using the least squares method. The initial weights of N monochromatic filaments are non-negatively truncated and normalized to obtain the theoretical weights of the N monochromatic filaments. Based on the theoretical weights and the total number of filaments m, the ratio of the number of N different monochromatic filaments is determined using the maximum remainder method.

[0014] In one embodiment, the initial weights of the N monochromatic filaments are non-negatively truncated and normalized to obtain the theoretical weights of the N monochromatic filaments, including: If the base colors of N monochrome filaments include colored base colors and white base colors, then: The initial weights of the colored base colors are truncated to non-negative values, and negative weights are removed. If the sum of the initial weights of the colored base colors after non-negative truncation is greater than 1, then the initial weights of all colored base colors are normalized to obtain the theoretical weights of all colored base colors, and the theoretical weight of the white base color is 0. If the sum of the initial weights of the colored base colors after non-negative truncation is less than or equal to 1, then the initial weights of the colored base colors are the theoretical weights. The theoretical weight of the white base color is 1 minus the sum of the theoretical weights of all the colored base colors. If the base color of N monochrome filaments is a colored base color, then: The initial weights of the colored base colors are truncated to non-negative values, and negative weights are removed. If the sum of the initial weights of the colored base colors after non-negative truncation is less than 1, then the initial weights of the colored base colors are the theoretical weights, and the base color closest to the target color segment is selected to supplement it. The theoretical weight of the supplemented base color is 1 minus the sum of the theoretical weights of all colored base colors. If the sum of the initial weights of the non-negative truncated base colors is greater than or equal to 1, then the initial weights of all base colors are normalized to obtain the theoretical weights of all base colors.

[0015] In one embodiment, the spiral wrapping and binding angle of the transparent strip is 30°~60°, the material of the transparent strip is thermoplastic transparent material, and the roundness tolerance of the customized color printing consumables after wrapping is controlled within ±0.05mm.

[0016] Secondly, a customized FDM color printing system based on multi-color filament ratios is provided, including: The color 3D model building unit is used to create a color 3D model of the color workpiece to be printed, divide the color 3D model into continuous two-dimensional slices, and obtain slice information, including the slice size, position, outline boundary and outer outline color. The printing strategy generation unit is used to automatically plan the printing strategy based on the slice information and generate a continuous color change filament model that matches the printing strategy. The yarn count ratio calculation unit is used to determine multiple color segments based on the continuous color change filament model, and extract the color requirements and length parameters of each color segment; according to the color requirements of each color segment, the multi-color filament ratio calculation method is used to calculate the yarn count ratio of N single-color filaments in each color segment; The color printing consumables preparation unit is used to prepare colored core filaments according to the ratio of the number of N monochrome filaments in each color segment and the length parameters of the corresponding color segment; the colored core filaments are spirally wrapped and bound with transparent strips to prepare customized color printing consumables. The printing unit is used to set the printing parameters of the FDM printer, feed customized color printing consumables into the printhead of the FDM printer, and complete the printing according to the printing strategy to obtain a color workpiece.

[0017] Thirdly, a colored workpiece is provided, which is obtained by the above-mentioned FDM customized color printing method based on the ratio of multi-color filaments.

[0018] Compared with the prior art, this application has the following beneficial effects: 1. By pre-mixing multi-color and single-color filaments, customized color printing consumables can be prepared. Full-color printing can be achieved with only a single-nozzle FDM printer, without the need for complex multi-nozzle or online color mixing structures. This significantly reduces the equipment threshold and cost of color FDM printing, while avoiding the lag and color mixing problems of online color mixing. Color switching is accurate and color reproduction is high.

[0019] 2. By synchronously matching the color 3D model and printing strategy with the software, a pre-transition color segment is added at the filament color change node. The length of the transition color segment is determined adaptively based on the nozzle melt cavity evacuation volume formula and the color contrast safety factor. The color change and color mixing process is transferred to the inside of the model or the support structure, realizing the precise correspondence between the filament color segment and the workpiece outer contour color node. Only the external color accuracy of the workpiece needs to be guaranteed, and the internal filling color can be set arbitrarily. While ensuring the appearance effect, the problem of color bleeding and color deviation on the outer contour is completely avoided, which greatly improves printing efficiency and reduces material waste.

[0020] 3. Transparent thermoplastic strips are used to synchronously spirally wrap and bind multi-colored filament cores, ensuring the stability of the core structure and the roundness accuracy of the filaments, avoiding problems such as filament scattering and poor filament feeding during printing. At the same time, the transparent strips and cores are made of the same thermoplastic material, which can melt synchronously in the nozzle without affecting the color mixing effect. Furthermore, by changing the materials of the core filaments and wrapping strips, 3D printing consumables with composite functions such as flexibility, high strength, and temperature resistance can be prepared, expanding the application scenarios.

[0021] 4. The diameter of the customized consumables prepared in this application can be adjusted according to needs, and it is compatible with most mainstream FDM printers on the market without the need to modify the equipment, making it highly versatile. The printed color workpieces have uniform color, high detail reproduction, are not easy to fade, and can be preserved for a long time. They are suitable for multiple fields such as product design, medical models, cultural creativity, and education. Attached Figure Description

[0022] This application can be better understood by referring to the description given below in conjunction with the accompanying drawings, which, together with the detailed description below, are incorporated in and form part of this specification. In the drawings: Figure 1 A flowchart of a customized FDM color printing method based on multicolor filament ratios is shown. Figure 2 A schematic diagram of the customized color printing consumables preparation process is shown. Detailed Implementation

[0023] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of the actual embodiments are described in the specification. However, it should be understood that many embodiment-specific decisions can be made in the development of any such actual embodiment to achieve the developer’s specific objectives, and these decisions may vary as the embodiments differ.

[0024] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the device structure closely related to the solution of this application is shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0025] It should be understood that this application is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, embodiments may be combined with each other, features may be substituted or borrowed between different embodiments, and one or more features may be omitted in one embodiment, where feasible.

[0026] This application provides a customized FDM color printing method based on multi-color filament ratios. Figure 1 A flowchart illustrating a customized FDM color printing method based on multi-color filament ratios is shown. See [link / reference]. Figure 1 The method mainly includes the following steps: Step S1: Create a color 3D model of the color workpiece to be printed, divide the color 3D model into continuous two-dimensional slices, and obtain the slice information, including the slice size, position, outline boundary and outer outline color.

[0027] Here, the color 3D model can be a red, white and blue cube 3D model. Extract the geometric dimensions of the model and the color data of the three adjacent faces (red bottom, white top, and blue sides). Input the color 3D model into slicing software and divide it into continuous two-dimensional slices with a standard layer thickness of 0.2mm to obtain the slicing information.

[0028] Step S2: Based on the slice information, automatically plan the printing strategy and generate a continuous color-changing filament model that matches the printing strategy.

[0029] Here, existing computer software is used to automatically plan the printing strategy and generate a continuous color-changing filament model. For example, PrusaSlicer can be used.

[0030] The printing strategy uses a composite scanning path that is biased from the outside in. The outer contour area of ​​the scanning path is printed with precise color separation, which corresponds one-to-one with the color segments of the continuous color-changing filament model. The inner filling area of ​​the scanning path is filled with any color.

[0031] Multiple color segments are all formal color segments. At each color switching node in the continuous color transformation filament model, a transition color segment is added. For example, at the color switching nodes from red to blue and from blue to white, a transition length is added before the next color segment. The color arrangement of the continuous color-changing filament model is synchronized with the printing strategy's outer contour printing sequence, printing speed (e.g., 50mm / s), and layer thickness parameters (e.g., 0.2mm). This ensures that the transition color segments are used preferentially for filling or supporting the printing inside the model, and are sufficient to empty the residual color in the nozzle, so that the color is uniform and pure when the formal color segments are extruded.

[0032] The official color segments precisely correspond to the color partitions of the three faces of the cube, ensuring that the external color accuracy of the three-color cube after printing meets the preset requirements, while there are no mandatory limitations on the internal colors.

[0033] Step S3: Based on the continuous color change filament model, determine multiple color segments. For the red, white and blue three-color cube 3D model, determine three color segments: red, white and blue. Extract the color requirements and length parameters of each color segment. According to the color requirements of each color segment, use the multi-color filament ratio calculation method to calculate the ratio of the number of N single-color filaments in each color segment.

[0034] Step S4: Based on the ratio of the number of N monochrome filaments in each color segment and the length parameters of the corresponding color segment, colored core filaments are prepared; the colored core filaments are spirally wrapped and bound with transparent strips to prepare customized color printing consumables. Figure 2 A schematic diagram of the customized color printing consumables preparation process is shown.

[0035] Step S5: Set the printing parameters of the FDM printer, feed the customized color printing consumables into the printhead of the FDM printer, and complete the printing according to the printing strategy to obtain a color workpiece.

[0036] In this embodiment, customized color printing consumables are prepared by pre-mixing multi-color and single-color filaments. Full-color printing can be achieved with only a single-nozzle FDM printer, without the need for complex multi-nozzle or online color mixing structures. This significantly reduces the equipment threshold and cost of color FDM printing, while avoiding the lag and color mixing problems of online color mixing. Color switching is accurate and color reproduction is high.

[0037] In one embodiment, the transition length is adaptively calculated based on the formula for the evacuation volume of the nozzle's melting chamber:

[0038]

[0039] in, The length of the transition color segment, This refers to the evacuation volume of the molten chamber in the FDM printer nozzle. To customize the cross-sectional area of ​​color printing consumables, To ensure color contrast safety, when transitioning from light to light or dark to dark colors... Take 1.5, any color to black Take 2.0, when changing from dark to light colors Choose 3.0~4.0. The inner diameter of the nozzle's thermal break zone. The length of the thermal break zone, The length of the nozzle conical cavity. This refers to the nozzle outlet orifice diameter.

[0040] In one embodiment, step S3 involves calculating the ratio of the number of N single-color filaments within each color segment using a multi-color filament ratio calculation method based on the color requirements of each color segment, including: First, calculate the total number m of monochromatic filaments that can be accommodated within the cross-section of a single customized consumable, including: Determine the outer diameter D of the finished consumable, the diameter d of a single monochrome filament, and the thickness t of the transparent coating strip on one side; Calculate the effective inner diameter of the layout: D usable = D - 2t; Calculate the diameter ratio: ratio = D usable / d; Based on the optimal density lookup table for circles with equal inner diameters, reverse the search to find the maximum integer number of filaments (m) that can be accommodated under the current diameter ratio.

[0041] Here, you can choose from five basic colors: cyan (C), magenta (M), yellow (Y), black (K), and white (W). The diameter of the single-color filament is 0.4mm, which is 1 / 4.375 of the diameter of the finished consumable material (1.75mm).

[0042] Then, the RGB values ​​of the base colors of the N monochrome filaments are converted to CMYK values ​​to obtain the base color CMYK matrix B; the RGB color values ​​of the target color segment are converted to CMYK values ​​to obtain the target color CMYK vector t; based on the base color CMYK matrix and the target color CMYK vector, the initial weights of the N monochrome filaments are obtained using the least squares method. Specifically, with the weight w of the base colors of the N monochrome filaments as unknowns, based on the base color CMYK matrix and the target color CMYK vector, the system of equations B·w ≈ t is constructed, and the solution is used to obtain the sum of squared residuals. The minimum weight vector w yields the initial weights for N monochromatic filaments.

[0043] Then, the initial weights of the N monochromatic filaments are non-negatively truncated and normalized to obtain the theoretical weights of the N monochromatic filaments.

[0044] The specific process is as follows: If the base colors of N monochrome filaments include colored base colors and white base colors, then: The initial weights of the colored base colors are truncated to non-negative values, and negative weights are removed. If the sum of the initial weights of the colored base colors after non-negative truncation is greater than 1, then the initial weights of all colored base colors are normalized to obtain the theoretical weights of all colored base colors, and the theoretical weight of the white base color is 0. If the sum of the initial weights of the colored base colors after non-negative truncation is less than or equal to 1, then the initial weights of the colored base colors are the theoretical weights. The theoretical weight of the white base color is 1 minus the sum of the theoretical weights of all the colored base colors. If the base color of N monochrome filaments is a colored base color, then: The initial weights of the colored base colors are truncated to non-negative values, and negative weights are removed. If the sum of the initial weights of the colored base colors after non-negative truncation is less than 1, then the initial weights of the colored base colors are the theoretical weights, and the base color closest to the target color segment is selected to supplement it. The theoretical weight of the supplemented base color is 1 minus the sum of the theoretical weights of all colored base colors. If the sum of the initial weights of the non-negative truncated base colors is greater than or equal to 1, then the initial weights of all base colors are normalized to obtain the theoretical weights of all base colors.

[0045] Then, based on the theoretical weights and the total number of filaments m, the ratio of the number of N different monochromatic filaments is determined using the maximum remainder method. This includes: The theoretical weights of the N basic colors are normalized to obtain the normalized proportions of the N basic colors. Calculate the theoretical floating-point roots of each basic color: ideal i = p i × m, where p i Let i be the normalized ratio of the i-th basic color, ideal i Let be the theoretical floating-point radical of the i-th basic color; Round each theoretical floating-point radical down to obtain the fundamental radical floor. i ; Calculate the remaining number of roots to be assigned: m - Σfloor i ; Sort the fractional parts of each theoretical floating-point root number from largest to smallest, and add 1 to each of the basic root numbers in turn to obtain the final integer root number ratio.

[0046] Specifically, the diameter of the monochrome filament is 1 / 150 to 1 / 3 of the diameter of the finished customized color printing consumable; the larger the number N of monochrome filaments and the smaller the diameter of the single filament, the wider the color gamut range that the customized color printing consumable can output.

[0047] Specifically, the spiral wrapping and binding angle of the transparent strip is 30°~60°, the material of the transparent strip is thermoplastic transparent material, and the roundness tolerance of the customized color printing consumables after wrapping is controlled within ±0.05mm.

[0048] Specifically, the materials of the monochrome filaments include any one or more of the same type of thermoplastic materials such as PLA, ABS, PETG, PA, TPU, PC, PPS, PEEK, PEKK, TPV, TPE, bio-based PLA, carbon fiber reinforced composite materials, glass fiber reinforced composite materials, conductive thermoplastic materials, high-temperature resistant engineering plastics, and flame-retardant thermoplastic materials; the materials of the transparent strips are thermoplastic materials of the same system as the monochrome filaments, with a melting temperature difference of ≤20℃.

[0049] Specifically, by replacing the monochrome filaments or transparent strips of different materials, composite functional 3D printing consumables can be prepared. The composite functions include, but are not limited to, one or more of the following: flexibility, high strength, temperature resistance, and flame retardancy.

[0050] Specifically, the printing parameters for the FDM printer are set as follows: layer height 0.05mm~0.4mm, nozzle temperature 180℃~260℃, printing speed 20mm / s~120mm / s, and heated bed temperature 30℃~110℃.

[0051] In one embodiment, the outer diameter of the finished consumable is set to D = 1.75 mm, the diameter of the monochrome filament is set to d = 0.4 mm, and the thickness of the transparent PLA strip is set to t = 0.1 mm; the effective inner diameter D is calculated. usable =1.75 - 2 × 0.1 = 1.55 mm; Diameter ratio D usable / d = 1.55 / 0.4 = 3.875; The interpolation algorithm of the inner diameter circle with dense arrangement table is called to find the maximum total number of filaments that the current cross-section can accommodate, m = 10. White top surface RGB (255,255,255): C=0.000, M=0.000, Y=0.000, K=0.000 Red background RGB (255,0,0): C=0.000, M=1.000, Y=1.000, K=0.000 Blue side RGB (0,0,255): C=1.000, M=1.000, Y=0.000, K=0.000 The five basic RGB colors of the silk fabric are cyan (0, 255, 255), magenta (255, 0, 255), yellow (255, 255, 0), black (0, 0, 0), and white (255, 255, 255). After converting them to their corresponding CMYK components, a system of linear equations is constructed and solved for each target color: White top face: Directly solve for 100% white and 0% for other colors.

[0052] Red background: The normalized theoretical ratio is 50% magenta and 50% yellow.

[0053] Blue side: The theoretical ratio after normalization is 50% cyan and 50% magenta.

[0054] Integer allocation optimization: With a total number of roots m=10, the maximum remainder method is used to distribute the roots, resulting in the actual quantity ratio for each segment: White top surface: 10 white threads, 0 threads of other colors Red background: 5 magenta sticks, 5 yellow sticks, 0 other colors.

[0055] Blue side: 5 cyan, 5 magenta, 0 other colors.

[0056] Taking the E3DV6 nozzle as an example, the inner diameter of the thermal break zone... =2.0mm, thermal break length =12.0mm, nozzle outlet orifice diameter =0.4mm, nozzle conical cavity length =5.0mm, the calculated volume of the molten cavity evacuation is: =π×(1.0)²×12+(π / 3)×5×[1.0²+0.2²+1.0×0.2]≈44.2mm³; cross-sectional area of ​​consumables =π×(0.875)²≈2.41mm²; Red to blue color segment (dark to dark): take k=1.5, =44.2 / 2.41×1.5≈28mm; Blue→White color segment (dark→light): take k=3, =44.2 / 2.41×3≈55mm; The calculated transition length is added to the front end of each color segment, and the transition color segment is used first for filling and printing inside the model.

[0057] Based on the calculated proportions of each segment, the strands are arranged and twisted according to the color requirements of the corresponding color segments to prepare continuous multicolor core yarns: White section: All sections are made of white PLA filaments twisted together.

[0058] Red section: Arrange magenta and yellow PLA filaments in a 1:1 ratio.

[0059] Blue section: Arrange cyan and magenta PLA filaments in a 1:1 ratio.

[0060] During the synchronous preparation of multi-colored core filaments, five filament feeders are set up according to five basic colors (CMYKW), with each feeder corresponding to one basic color. Each feeder is equipped with a magnetically damped tension controller, with a uniform tension setting of 2N and a deviation controlled within ±0.2N. Each feeder feeds out the corresponding color filaments as needed according to the S304 ratio. For example, the red segment is fed out by the magenta feeder with 5 magenta filaments, the yellow feeder with 5 yellow filaments, and the other feeders do not feed out any filaments. The filaments fed out by each feeder are laid out side by side in a flat manner. The multi-color filament bundle is gathered into a circular cross-section by a converging and rolling mechanism, which is a tapered tapered channel with a circular exit end. After the filament bundle is compressed to the target cross-section by a compression and sizing mold, it is spirally wrapped and bound with transparent PLA strips at a 45° helix angle and 50% overlap. The wrapping tension is set to 5N and the pitch is approximately 3.89mm. The entire arrangement and wrapping process is carried out at room temperature (25℃). After sizing, a customized color printing consumable with an outer diameter of 1.75mm and a roundness tolerance controlled within ±0.05mm is obtained.

[0061] Set the printing parameters: layer height 0.2mm, nozzle temperature 210℃, printing speed 50mm / s, heated bed temperature 60℃; feed the prepared customized color printing consumables into the single nozzle filament feeding mechanism of the FDM printer. After the consumables are heated and melted by the nozzle, the internal multi-color filaments and the transparent coating layer melt and mix synchronously to generate the target color of the corresponding color segment. Then, according to the preset printing strategy, the FDM forming printing is completed layer by layer, and finally a red, white and blue three-color cube workpiece with pure colors on three sides, clear boundary lines and no color bleeding or color deviation is obtained.

[0062] Employing the same inventive concept as the FDM customized color printing method based on multi-color filament ratio, this embodiment also provides a corresponding FDM customized color printing apparatus based on multi-color filament ratio, comprising: The color 3D model building unit is used to create a color 3D model of the color workpiece to be printed, divide the color 3D model into continuous two-dimensional slices, and obtain slice information, including the slice size, position, outline boundary and outer outline color. The printing strategy generation unit is used to automatically plan the printing strategy based on the slice information and generate a continuous color change filament model that matches the printing strategy. The yarn count ratio calculation unit is used to determine multiple color segments based on the continuous color change filament model, and extract the color requirements and length parameters of each color segment; according to the color requirements of each color segment, the multi-color filament ratio calculation method is used to calculate the yarn count ratio of N single-color filaments in each color segment; The color printing consumables preparation unit is used to prepare colored core filaments according to the ratio of the number of N monochrome filaments in each color segment and the length parameters of the corresponding color segment; the colored core filaments are spirally wrapped and bound with transparent strips to prepare customized color printing consumables. The printing unit is used to set the printing parameters of the FDM printer, feed customized color printing consumables into the printhead of the FDM printer, and complete the printing according to the printing strategy to obtain a color workpiece.

[0063] The FDM customized color printing system based on multi-color filament ratio in this embodiment has the same inventive concept as the FDM customized color printing method based on multi-color filament ratio described above. Therefore, the specific implementation of this system can be found in the embodiment section of the FDM customized color printing method based on multi-color filament ratio described above, and its technical effects correspond to the technical effects of the above method, so they will not be repeated here.

[0064] This application also provides a colored workpiece, which is obtained by the FDM customized color printing method based on the multi-color filament ratio of the aforementioned embodiments.

[0065] The above descriptions are merely various embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A customized FDM color printing method based on multi-color filament ratio, characterized in that, include: A color 3D model of the workpiece to be printed is created, the color 3D model is divided into continuous two-dimensional slices, and the slice information is obtained, including the slice size, position, outline boundary and outer outline color. Based on the slice information, a printing strategy is automatically planned, and a continuous color-changing filament model matching the printing strategy is generated. Based on the continuous color change filament model, multiple color segments are determined, and the color requirements and length parameters of each color segment are extracted. According to the color requirements of each color segment, a multi-color filament ratio calculation method is used to calculate the ratio of the number of N single-color filaments in each color segment. Based on the ratio of the number of N monochrome filaments in each color segment and the length parameters of the corresponding color segment, colored core filaments are prepared; transparent strips are used to spirally wrap and bind the colored core filaments to prepare customized color printing consumables. Set the printing parameters of the FDM printer, feed the customized color printing consumables into the printhead of the FDM printer, and complete the printing according to the printing strategy to obtain a color workpiece.

2. The method as described in claim 1, characterized in that, The printing strategy uses a composite scanning path that is biased from the outside in. The outer contour area of ​​the scanning path is printed with precise color separation, which corresponds one-to-one with the color segments of the continuous color-changing filament model. The inner filling area of ​​the scanning path is filled with any color.

3. The method as described in claim 1, characterized in that, All of the color segments are formal color segments, and a transition color segment is added at each color switching node of the continuous color transformation filament model.

4. The method as described in claim 3, characterized in that, The length of the transition color segment is calculated using the following formula: in, The length of the transition color segment, This refers to the evacuation volume of the molten chamber in the FDM printer nozzle. To customize the cross-sectional area of ​​color printing consumables, For color contrast safety factor, The inner diameter of the nozzle's thermal break zone. The length of the thermal break zone, The length of the nozzle conical cavity. This refers to the nozzle outlet orifice diameter.

5. The method as described in claim 1, characterized in that, The color arrangement of the continuous color-changing filament model is synchronously matched with the outer contour printing sequence, printing speed, and layer thickness parameters of the printing strategy.

6. The method as described in claim 1, characterized in that, Based on the color requirements of each color segment, a multi-color filament ratio calculation method is used to calculate the ratio of the number of N single-color filaments within each color segment, including: Calculate the total number of monochromatic filaments (m) that can be accommodated within the cross-section of a single customized consumable; The RGB values ​​of the base colors of the N monochrome filaments are converted to CMYK values ​​to obtain the base color CMYK matrix; the RGB color values ​​of the target color segments are converted to CMYK values ​​to obtain the target color CMYK vector; based on the base color CMYK matrix and the target color CMYK vector, the initial weights of the N monochrome filaments are obtained using the least squares method. The initial weights of N monochromatic filaments are non-negatively truncated and normalized to obtain the theoretical weights of the N monochromatic filaments. Based on the theoretical weights and the total number of filaments m, the ratio of the number of N different monochromatic filaments is determined using the maximum remainder method.

7. The method as described in claim 6, characterized in that, The initial weights of the N monochromatic filaments are non-negatively truncated and normalized to obtain the theoretical weights of the N monochromatic filaments, including: If the base colors of N monochrome filaments include colored base colors and white base colors, then: The initial weights of the colored base colors are truncated to non-negative values, and negative weights are removed. If the sum of the initial weights of the colored base colors after non-negative truncation is greater than 1, then the initial weights of all colored base colors are normalized to obtain the theoretical weights of all colored base colors, and the theoretical weight of the white base color is 0. If the sum of the initial weights of the colored base colors after non-negative truncation is less than or equal to 1, then the initial weights of the colored base colors are the theoretical weights. The theoretical weight of the white base color is 1 minus the sum of the theoretical weights of all the colored base colors. If the base color of N monochrome filaments is a colored base color, then: The initial weights of the colored base colors are truncated to non-negative values, and negative weights are removed. If the sum of the initial weights of the colored base colors after non-negative truncation is less than 1, then the initial weights of the colored base colors are the theoretical weights, and the base color closest to the target color segment is selected to supplement it. The theoretical weight of the supplemented base color is 1 minus the sum of the theoretical weights of all colored base colors. If the sum of the initial weights of the non-negative truncated base colors is greater than or equal to 1, then the initial weights of all base colors are normalized to obtain the theoretical weights of all base colors.

8. The method as described in claim 1, characterized in that, The spiral wrapping and binding angle of the transparent strip is 30°~60°. The transparent strip is made of thermoplastic transparent material. After wrapping, the roundness tolerance of the customized color printing consumables is controlled within ±0.05mm.

9. A customized FDM color printing system based on multi-color filament ratio, characterized in that, include: A color 3D model building unit is used to create a color 3D model of a color workpiece to be printed, divide the color 3D model into continuous two-dimensional slices, and obtain slice information, including the slice size, position, outline boundary and outer outline color. A printing strategy generation unit is used to automatically plan a printing strategy based on the slice information and generate a continuous color-changing filament model that matches the printing strategy. The thread count ratio calculation unit is used to determine multiple color segments based on the continuous color change filament model, and extract the color requirements and length parameters of each color segment; according to the color requirements of each color segment, the multi-color filament ratio calculation method is used to calculate the thread count ratio of N single-color filaments in each color segment; The color printing consumables preparation unit is used to prepare colored core filaments according to the ratio of the number of N monochrome filaments in each color segment and the length parameters of the corresponding color segment; the colored core filaments are spirally wrapped and bound with transparent strips to prepare customized color printing consumables. The printing unit is used to set the printing parameters of the FDM printer, feed customized color printing consumables into the printhead of the FDM printer, and complete the printing according to the printing strategy to obtain a color workpiece.

10. A colored workpiece, characterized in that, The result is obtained using the FDM customized color printing method based on the multicolor filament ratio as described in any one of claims 1-8.

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