Adaptive slicing compatible pre-curing type three-dimensional color printing technology

Abstract

The invention discloses a self-adaptive slicing compatible pre-curing type three-dimensional color printing technology, and belongs to the technical field of machinery-photoelectricity. Depending on an ink-jet printing head and diversified color ink, the purpose of three-dimensional color printing is achieved in a transfer curing mode of a transparent substrate. According to the printing technology, self-adaptive slice adaptation, pre-curing treatment and sub-slice insertion glue spraying are organically carried out, and a common area light source and a laser scanning or LCD or DLP area array light source are used; repeating the printing and layer cutting process, the self-adaptive slice pre-curing and aligning process and the transfer curing process in cycles; and the formed object can be heightened and grown on the lifting table again and again, printing of the whole object is finally completed, and a single-color or colorful high-precision three-dimensional printing product is finally generated.

Description

[0001] [Area of ​​expertise]

[0002] This invention belongs to the field of mechanical-optoelectronic technology. To be precise, it is a new rapid prototyping process (MJP: Multi-jet modeling (pringting): multi-nozzle jetting process) using inkjet printheads, which is a full-color 3D printing method that uses 3DP (three-dimensional printing) to spray and solidify the colored shell layers. [Background Technology]

[0003] Multi-jet modeling (MJP) is a new rapid prototyping process that uses direct inkjet deposition to produce smooth, high-resolution plastic parts with complex geometries. The entire process requires only a UV lamp and photosensitive material. This technology originated from 3D printing technology based on 3D printing techniques (3DP). It was developed by Emanuel Sachs and others at MIT.

[0004] EMSachs applied for a 3DP (Three-Dimensional Printing) patent in 1989, which is one of the core patents in the field of non-formable material micro-droplet jetting. Later, the American brand 3DSystems changed the above-mentioned "non-formable material micro-droplet jetting" to "micro-droplet jetting of photosensitive resin-based forming materials, combined with photocuring for layer-by-layer printing-like forming," thus creating another type of color printing technology and commercial models: such as the 3DSystems ProJet 3600 model.

[0005] A general overview of the historical development of 3D printing:

[0006] In 1986, American PhD Charles W. Hull proposed the concept of using lasers to irradiate and solidify photosensitive resin surfaces to create three-dimensional objects in a paper. Subsequently, Charles W. Hull applied for related patents. Charles Hull developed the first commercial 3D printer. SLA was the first molding technology proposed and commercially applied; in 1988, 3D Systems manufactured the world's first SLA-3D printer.

[0007] In 2017, German sportswear brand Adidas launched the world's first athletic shoe with a 3D-printed sole using SLA technology, planning to begin mass production in 2018 to meet the demands of rapidly changing fashion trends and produce more customized products. While SLA technology offers fast molding speeds and high precision, shrinkage during resin curing inevitably leads to stress or deformation. Therefore, developing photosensitive materials with low shrinkage, fast curing, and high strength is a key trend in its development.

[0008] There are many different technologies involved in 3D printing. They differ in the way they use available materials and how they build parts by constructing different layers. Commonly used materials for 3D printing include nylon fiberglass, polylactic acid, ABS resin, durable nylon materials, plaster materials, aluminum materials, titanium alloys, stainless steel, silver plating, gold plating, and rubber-like materials.

[0009] Technical principles and overview of photopolymer 3D:

[0010] The basic printing process: The design process for 3D printing of unmanned aerial vehicles by British engineers involves first creating a model using computer modeling software, then dividing the completed 3D model into layer-by-layer sections, or slices, to guide the printer in printing layer by layer. The standard file format for collaboration between the design software and the printer is the STL file format. An STL file uses triangular faces to approximate the surface of an object. The smaller the triangular faces, the higher the surface resolution of the generated surface. PLY is a scanner that generates 3D files through scanning; its generated VRML or WRL files are often used as input files for full-color printing.

[0011] Slicing: The printer reads the cross-sectional (slicing) information from the file, prints these slices layer by layer using a liquid material, and then glues the layers together in various ways to create a printed object. The advantage of this technology is that it can create objects of almost any shape.

[0012] 3D printers using direct deposition printing with inkjet heads typically produce slices with thicknesses (vertical, Z-axis) and planar (XY-axis) resolutions measured in dpi (pixels per inch) or micrometers. Typical thicknesses are 20-100 micrometers (0.1 millimeters), although some printers, such as the Objet Connex series and 3D Systems' ProJet series, can print layers as thin as 16 micrometers. Planar resolutions are comparable to laser printers. The diameter of the printed "ink droplets" is typically 50 to 100 micrometers. Creating a model using traditional methods usually takes hours to days, depending on the model's size and complexity. 3D printing technology can reduce this time to a few hours, though this depends on printer performance and the model's size and complexity.

[0013] Traditional manufacturing techniques such as injection molding can mass-produce polymer products at a relatively low cost, while 3D printing technology can produce relatively small quantities of products faster, more flexibly, and at a lower cost. A desktop-sized 3D printer can meet the needs of designers or concept development teams to create models.

[0014] In summary, the completion of 3D printing: First, the resolution of 3D printers is sufficient for most applications (it may be relatively rough on curved surfaces, like jagged edges in an image). To obtain higher resolution items, the following method can be used: first print a slightly larger object with the current 3D printer, and then slightly polish the surface to obtain a smooth "high resolution" item.

[0015] Some technologies can use multiple materials for printing simultaneously. Some technologies also use supports during the printing process; for example, when printing objects that are upside down, easily removable materials (such as soluble materials) are needed as supports.

[0016] For each layer of coating, the 2D planar motion of the inkjet head is achieved by independent orthogonal X and Y guide rails. The two guide rails are placed horizontally and orthogonally, or the planar displacement of the inkjet head can be achieved through a dual-axis hinge structure where a fixed vertical axis drives a vertical moving axis. Generally, the inkjet head synchronously drives two nozzles, and the distance between the nozzles and the forming surface of the printed slice is within 1 mm.

[0017] Since multi-nozzle spraying is selective spraying based on object slices, the irradiation position of the curing light source does not need to be selected. A large area of ​​ultraviolet light illuminates the entire surface of the slice, ensuring that the areas sprayed with the material to be cured are cured. This eliminates the need for area-selective light valve light sources such as laser scanning or DLP / LCD. The structure is simplified. Finally, after this process is completed, the object is cleaned. This results in a clean object. After the prototype is removed from the resin, final curing is performed. Of course, secondary processing is still required. Typically, we first separate or remove the support points, i.e., the additional structures attached to the printed object, using tools or solvents. Then, polishing, electroplating, painting, or coloring treatments are applied to obtain the desired product. [Summary of the Invention]

[0018] The purpose of this invention is to overcome the shortcomings of current up-pull (also known as resin tank type, inverted photopolymer 3D printer) photopolymer 3D printing technology, which cannot print high-resolution colors. By using a transparent substrate to inkjet print the current slice, the surface color ink layer of the printed object is established on the mechanism of inward expansion, surface pre-curing and hardening, and redundant space of internal honeycomb cavities. This ensures the accuracy of the object's appearance while taking into account the coordination mechanism of surface coloring. It can also be matched with a simplified open-loop control mechanism.

[0019] The invention features a unique adaptive slicing physical structure, selectively combining curing, semi-curing, and interspersed adhesive spraying modes to improve the accuracy and color resolution of printed objects.

[0020] Adaptive slicing overcomes the obstacles posed by the preset slice thickness and open-loop stacking in current technologies. When performing 3D stacking in an open-loop manner, since the preset layer thickness of each slice is the same, ideally, the increase in thickness of each layer of the printed object is uniform, meaning the increase in the total layer thickness is linear. However, in reality, due to factors such as material elasticity and curing deformation, the increase in the total layer thickness of the printed object deviates from linearity, causing the "curing gap" to gradually increase or decrease. In reality, the thickness of each inkjet slice (ink jet volume from the inkjet head), object deformation, and curing shrinkage all exist. Any tiny deviation in layer-by-layer parameters will lead to a cumulative deviation in the total stacked thickness, causing the "printing layer gap" to gradually become too large or too small (or too loose or too tight), deviating from the preset layer thickness. This results in poor print quality or printing failure. Even without monitoring the stacked thickness, the reserved layer thickness for each slice is the same. Therefore, adaptive slicing is needed to fully adapt to the technical form of this invention, as detailed below.

[0021] *Background of the conventional structures and processes upon which this invention is based:

[0022] The inkjet printhead components required to achieve this full-color printing method include: preform ink printheads, support ink printheads, and color ink printheads. Preform ink printheads are used for the main material of the inkjet object, producing multiple colors with a large ink volume from the nozzle. Support ink printheads are used to create the support structure for the inkjet-generated printed object, and can be dissolved by water or organic solvents after printing. Color ink printheads are used to generate the surface color of the printed object, producing fine color mixing and good color compatibility. Each type of printhead has at least one nozzle. In some cases, when only printing multi-color objects, the preform ink printhead alone can be used.

[0023] The necessary mechanical and electronic components for realizing the present invention also include: a mechanical device for driving the inkjet printhead, a height-adjustable printing platform (a platform for carrying the printed object), a transparent substrate (a substrate for carrying the current slice), an electronic control system, a support housing, and a curing light source (the light source includes: a common surface light source laser scanning or an LCD or DLP surface array light source). The specific connection relationship is as follows: the mechanical system maintains the relative movement of the printing platform device and the transparent substrate by changing the distance (or the transparent substrate can move up and down), the mechanical system maintains the controllable two-dimensional relative movement between the inkjet printhead and the transparent substrate, and the liquid infusion tubes connecting each printhead and the color ink reservoir (including the molded ink and the color ink reservoir) and the support reservoir are installed in a compact structure with separate or integrated installation.

[0024] The basic operation process for implementing this invention is as follows:

[0025] First, the printer's components undergo a general initialization procedure, including the printing platform rising and resetting to maintain its distance from the transparent substrate. The printing process involves the electronic control system instructing the mechanical system to move the inkjet printhead assembly and spray a pre-edited slice of the object's content onto the transparent substrate. If pre-curing is required, a pre-curing process is then performed on the slice on the transparent substrate: after pre-curing the slice, the electronic and mechanical systems drive the printing platform to descend closer to the transparent substrate and stop at a distance maintaining a preset layer thickness, thus aligning the slice with the printing platform or the cross-section of the printed object. Final curing then occurs. After final curing, the slice is cured and bonded to the cut surface of the printed object, increasing its thickness by one slice. This process is repeated continuously: slice preparation – slice pre-curing (pre-curing is optional) and alignment – ​​transfer curing. The printed object is gradually increased in height on the printing platform, ultimately completing the printing of the entire object.

[0026] Inkjet slicing process: An electronic control system drives the inkjet printhead to move and spray pre-edited slices of an object onto a transparent substrate. These slices include both molding and support ink. The surface of the transparent substrate is non-stick, facilitating subsequent curing and transfer. The slices may include both molding and support ink, or only molding ink, or only support ink. Because the transparent substrate is a continuous, planar structure, any complex pattern can easily be formed into a thin film.

[0027] Slice alignment process:

[0028] The printing platform is driven and brought close to the transparent substrate, maintaining a distance of one slice. Simultaneously, the outline of the printed object, cured on the printing platform, is aligned precisely with the slice on the platform, meaning the outline of the printed object is in contact with the slice. Due to the viscosity and surface tension of the photosensitive ink, the slice adheres to the printed object. This process continues until the distance between the cured section of the printed object and the transparent substrate equals the thickness of the current slice. At this point, the cured section of the printed object will contact the current slice, completing the slice alignment process.

[0029] Transfer and curing process:

[0030] The curing process after alignment is called the transfer curing process. Next, the current slice is irradiated with light (usually ultraviolet light curing) from the back (bottom) of the transparent substrate. After irradiation, the ink in the slice is cured and firmly adhered (transferred) to the current slice of the printed object. The printed object is increased by the thickness of a slice, thus completing the construction process of a slice.

[0031] *Background of the "colored shell" slice upon which this invention is based:

[0032] The outermost layer of the "colored shell" of the slice corresponds to the surface of the printed object, and only surface coloring is required for color printing. From the surface inwards, the layers are: transparent shell, color mixing layer, base color layer, and structural layer. Each of these layers is formed by inkjet printing from the ink reservoir (including the pre-formed ink and the ink cartridge). The characteristics are: transparent shell: color mixing layer: base color layer: structural layer: (The supporting structure of the ink reservoir is formed by inkjet printing and removed after printing. It is unrelated to color and will not be repeated).

[0033] Transparent shell: Transparent UV material (Transparent surface: requires high hardness)

[0034] Color layer: Multi-color ink mixture (Inner layer: Emphasizes color saturation, can have lower hardness)

[0035] Base layer: to highlight the colored layer (secondary inner layer: to enhance color temperature and saturation)

[0036] Internal structure: Supporting main body (solid or hollow: supporting structure, which can be a honeycomb-like porous structure)

[0037] Construction order of colored shell layers: The recommended order for better results is to first lay the transparent shell layer and the base color layer, and then lay the colored layer. This is more beneficial for the color effect because the ink of the colored layer with excellent color has good fluidity and mixing properties. If it is sprayed first, there is a possibility of it flowing, which needs to be restrained by the groove between the transparent shell layer and the base color layer.

[0038] The various "colorful shell" structures include the following six combinations:

[0039] A combination of a transparent shell layer, a colored layer, and a base color layer (3 layers) is used for top-quality color printing.

[0040] A combination of color layer and base layer (2 layers, without a transparent shell) is used for fine color printing.

[0041] A combination of a transparent shell and a colored layer (2 layers, without using a base color layer) is used to simplify color printing.

[0042] A combination of a transparent shell layer and a base color layer (2 layers, without using a color layer) is used to simplify multicolor printing.

[0043] A single base color layer combination (1 layer, without using a transparent shell layer + color layer) is used for monochrome and multicolor printing.

[0044] A single color layer combination (1 layer, without using a transparent shell layer + base color layer) is used to simplify color printing.

[0045] *The three proprietary core technologies of this invention:

[0046] Adaptive slicing compatible pre-cured printing processes include the following 3 sub-processes:

[0047] The adaptive slicing process, the pre-curing process, and the sub-slice insertion (adhesive spraying) process.

[0048] *Adaptive slicing process:

[0049] The adaptive slice structure: The thickness of the adaptive slice is 1%-50% greater than the "preset layer thickness". The surface layer of the slice retains a solid structure of 0.2mm-50mm. Under the solid structure of the surface layer of the slice, a honeycomb structure is designed. The honeycomb structure is a collection of numerous cavities surrounded by conventional crisscrossing grid walls. The ratio of the total area of ​​the grid walls and cavities determines the fill rate of the printed object.

[0050] The necessity of adaptive slicing: Adaptive principle: When the printing platform moves down to adhere to the current slice layer, the platform or the printed object will apply pressure to the current slice layer. If the thickness of the adaptive slice is greater than the "preset layer thickness", the pressure of the printed object can cause the current slice layer to expand and deform. If the current slice layer is completely solid, it will be severely squeezed and expanded, deviating greatly from the predetermined shape. However, the honeycomb-like porous structure of the adaptive slice has a certain redundant space for storing material, which reserves inward space for the current slice to expand and deform under pressure, thereby offsetting and suppressing the expansion of the slice under pressure and maintaining the basic shape unchanged. At the same time, it can also absorb the deviation of the thickness of the current slice layer. There is no need for closed-loop control of the printing thickness or the thickness of the current slice layer.

[0051] *Pre-curing process:

[0052] The necessity of pre-curing: In the implementation of the adaptive slicing principle, the deformation caused by the printing platform applying pressure to the current slice layer expands in all directions. Since a portion of the expansion component will inevitably move towards the surface of the printed object, it will inevitably affect the appearance and size of the printed object. Therefore, it is necessary to adopt the pre-curing principle for the current color shell layer or the part of the current color shell layer with lower viscosity.

[0053] Pre-curing methods: Selective pre-curing or full pre-curing: In selective pre-curing, before the printing platform comes into contact with the object, laser scanning or LCD / DLP array light sources are used to selectively cure the surface areas of the object (within a depth of 0.2mm-50mm from the surface). This increases the strength of the surrounding material of the current slice layer. When the printing platform then brings the object into contact with the current slice layer, the increased hardness of the surrounding material significantly hinders the expansion of uncured material towards the surface, forcing the uncured material to expand into the internal honeycomb pore structure, thus achieving a stable appearance. Alternatively, uniform pre-curing can be used to cure the entire slice, with a higher exposure dose on the surface. Pre-curing methods are classified as semi-cured or fully cured in terms of the degree of curing. Semi-curing refers to a relatively low exposure dose without complete curing, allowing the current slice layer to retain a certain degree of softness and fluidity.

[0054] *Sub-slice insertion process (adhesive spraying):

[0055] To ensure a strong bond between the current slice layer and the printed object, selective adhesive spraying is performed. After the pre-cured, semi-hardened current slice, selective or full-section adhesive spraying is applied to the surface of the current slice. Alternatively, selective adhesive spraying can be applied to the cut surface of the already formed printed object or to the surface of the current slice. The adhesive can be UV-curable glue or the corresponding color ink used in the current slice (a thin layer of ink is sprayed again for curing and bonding). The sprayed content is either a layer of transparent glue or a layer of printed content in the same color as the current slice. The thickness of the adhesive layer is 1%-80% of the thickness of the current slice. The purpose of adhesive spraying is to strengthen the bond while increasing printing efficiency and preventing excessive deformation of the printed slice.

[0056] *The operational procedures of this invention include three categories:

[0057] The first type of process combination consists of: inkjet generation of adaptive slicing process, adaptive slicing pre-curing process and selective insertion of sub-slices (or adhesive spraying process), and finally slicing transfer and curing process; adaptive slicing is completed in 3D drawing or generated in slicing software workflow.

[0058] The second type of process combination consists of, in order: conventional inkjet (the conventional non-adaptive slicing method of this invention, which is the existing slicing method in the industry) slicing process, slicing pre-curing process and selective insertion of sub-slices (or adhesive spraying) process, and finally, the pre-cured slicing transfer and curing process.

[0059] The third type of process combination consists of: inkjet printing to generate adaptive slicing process, followed by direct adaptive slicing transfer and curing process.

[0060] The beneficial effects of this invention are:

[0061] Compared to similar technologies: adaptive slicing eliminates the contradiction of error accumulation between open-loop control and the current slice layer thickness, simplifying the entire control system; the use of the "color shell" concept makes color expression more perfect; the organic combination of pre-curing and adaptive slicing achieves accurate object shape and the potential to improve printing speed. [Image Description]

[0062] Figure 1 A schematic diagram illustrating the principle of generating ordinary color slices on a transparent substrate.

[0063] Figure 2 Schematic diagram of inkjet transfer photopolymerization 3D color printing technology.

[0064] Figure 3 Schematic diagram of the adaptive slice structure and colored shell structure of this invention.

[0065] Label Explanation:

[0066] (1) Inkjet printhead (can be integrated, without the need for separate ink supply tubes and ink reservoirs)

[0067] (2) Lead screw

[0068] (3) Guide column

[0069] (4) Z-axis motor

[0070] (6) Color ink cartridge

[0071] (7) Support the ink cartridge

[0072] (8) Plain section

[0073] (9) Rocker arm

[0074] (10) Printing platform

[0075] (11) Direction of lifting and lowering motion

[0076] (12) Printed objects

[0077] (13) Motion rotating shaft

[0078] (14) Fix the rotating shaft

[0079] (15)Transparent substrate

[0080] (16) Printing platform bracket

[0081] (17) UV curing light

[0082] (18) Structural shell

[0083] (20) UV curing lamp

[0084] (21) Arrow

[0085] (22) Fixed column

[0086] (23) Inkjet printhead assembly

[0087] (24) Colored shell

[0088] (24-1) Transparent layer

[0089] (24-2) Color ink layer

[0090] (24-3) Base layer

[0091] (24-4) Structural (inner) layer

[0092] (25) Adaptive slicing

[0093] (25-1) Porosity of structural layers

[0094] (25-2) Pore walls of structural layers

[0095] (25-3) Colored shell region

[0096] (26) Adaptive slice local magnification

[0097] (27) The current slice is complete.

[0098] (28) Rotating arm

[0099] (29) Shell

[0100] [Best Implementation]

[0101] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments:

[0102] like Figure 1 , Figure 2 As shown:

[0103] To better understand this invention, let’s first familiarize ourselves with the prior art’s process of using inkjet components to spray (current) ordinary cross-sections (8):

[0104] The color ink reservoir (6) and the support ink reservoir (7) installed in the housing (29) are connected to the inkjet printhead (1) via the infusion tube (9). The support ink printhead, color ink printhead and molding ink printhead of the printhead module respectively print the current slice (8). The color ink reservoir (6) contains both color ink and molding ink. The color ink and molding ink printhead and ink reservoir are not drawn separately in the figure. In some cases, the color ink and molding ink are the same type. The color ink has at least 3 colors and more than 6 colors to mix and produce rich colors.

[0105] The horizontal displacement of the inkjet printhead (1) is achieved by the fixed rotating shaft (14) driving the rotating arm (28) to drive the moving rotating shaft (13) to make a circular motion; the inkjet printhead (1) is fixedly mounted on the rocker arm (9), and the rocker arm (9) is rigidly connected to the moving rotating shaft (13); each rotating shaft is driven by a conventional motor (not shown).

[0106] Arrow (21) points to the transparent substrate (15) after it has been lowered (avoiding obstruction), and the current ordinary slice (8) can be clearly seen. UV ink (ultraviolet curing) is ejected by the inkjet head. The thickness of the ink layer can be selected, ranging from a few micrometers to tens of micrometers.

[0107] Since the transparent substrate (15) is a continuous planar structure, any complex pattern can easily generate a thin layer of ink film.

[0108] especially Figure 2As shown: The equipment of this type of technology generally includes: a printing platform support (16) supporting a Z-axis motor (4), a lead screw (2), and a guide column (3), which constrains the vertical movement of the printing platform (10). Other basic structures are: the Z-axis motor (4) drives the lead screw (2) to make the printing platform (10) vertically displaced under the constraint of the guide column (3), as shown in the lifting direction (11); when the current slice 1 (8) is sprayed during the current slicing process, the printing platform (10) is raised to a sufficient thickness so that the 2D moving printhead of the inkjet printhead assembly (23) runs between the printing platform (10) and the transparent substrate (15); the fixing column (22) is used to fix the transparent substrate (15) and keep it stationary. The completed slice is shown in the figure below indicated by the arrow: the completed current slice (27).

[0109] Figure 2 The diagram shows that after the current slicing process is completed, the inkjet assembly (23) is retracted, and each printhead is moved out of the area between the printing platform (10) and the transparent substrate (15) by the fixed rotating shaft (14) driving the rotating arm to move the rotating shaft (13), in preparation for the subsequent slicing alignment process and transfer curing process.

[0110] Traditional techniques do not have a pre-curing process. If a pre-curing process is required, it should be performed first, followed by the slicing alignment process described below.

[0111] During the subsequent slice alignment process, the printing platform (10) (whose surface is easy to adhere to the ink, so that the slice can easily be bonded during the printing and curing process) is inverted and carries the printed object (12) down until the distance between the cured section of the printed object (12) and the transparent substrate (15) is equal to the thickness of the current slice (8). At this point, the cured section of the printed object (12) will contact the current slice (8), and the slice alignment process is completed.

[0112] Next is the transfer curing process: the UV curing lamp (20) emits UV curing light (17) which shines through the transparent substrate (15) from below to irradiate the slice and perform photocuring.

[0113] A scraper can be selected to clean the surface of the transparent substrate, and the cleaning can be performed once during each curing interval to remove residual ink. The structural housing (18) and other components, such as mechanical systems and control systems, are well-known technologies and will not be described again.

[0114] like Figure 3 As shown:

[0115] The concept of color shell and adaptive slicing is one of the core technologies of this invention. From the enlarged view of the adaptive slice on the right (26), it can be seen from the cut layered structure that the complete color shell (24) is composed of the outermost transparent layer (24-1), the high-resolution color ink layer (24-2), the base color layer (24-3), and the attached structural layer (24-4).

[0116] The current adaptive slice (25) on the transparent substrate (15) is constructed except for the colored shell layer (25-3); it is composed of a large number of structural layer pores (25-1) and structural layer pore walls (25-2); since the honeycomb structure of the structural layer (24-4) in the left figure is too small, it is not easy to show the details of the structural layer (24-4), and it is only expressed by dots. The real details are shown in the enlarged part (26).

[0117] In addition, pre-curing and selective curing are also core technologies of this invention: before the current adaptive slice (25) is aligned with the printed object on the printing platform, a laser scanning light source can be used to selectively cure the area of ​​the colored shell layer (24) of the current adaptive slice (25), or to cure it to a depth of 0.2-50 mm into the structural layer (24-4), while most areas of the structural layer (24-4) do not need to be exposed for curing. The light source dosage for pre-curing can be controlled appropriately, and insufficient curing exposure is called "semi-curing" exposure. In this way, the curing hardness of the resin and other inks in the curing area can be controlled, and the material can retain a little compressibility.

[0118] The tolerance of the adaptive slice to its own thickness (the thickness of the compressed adaptive slice) is obvious. When the adaptive slice (25) is aligned and in contact with the printed object, the pressure will cause the ink in the structural layer (24-4) to expand. Most of the expanded ink will be absorbed and contained by the pores (25-1) of the structural layer, which will result in a smaller area of ​​the pores. Since the ink in the pre-cured color shell layer becomes harder, it restricts the expansion of the ink in the structural layer (24-4) towards the surface of the printed object, thus ensuring the accuracy of the shape of the printed object.

[0119] Choosing to spray an adhesive layer onto the upper surface of the adaptive slice (25) has two implications: First, it is laid in the cured or semi-cured area of ​​the current slice to improve the adhesion between the current slice and the printed object; second, it also provides a way to increase the printing speed: it supports the option to select a thicker current slice (not necessarily an adaptive slice), and semi-curing or fully curing in advance is beneficial for stacking thicker slices, because before it is aligned and in contact with the printed object, there is space to cure the current slice from the upper and lower surfaces of the transparent substrate at the same time, resulting in good exposure; the choice of the adhesive layer material is also more flexible, as long as it meets the requirement of good adhesion strength, so that the adhesive layer is thinner, and the adhesive properties can be heat-sensitive or pressure-sensitive curing.

Claims

1. An adaptive slicing compatible pre-cured 3D color printing technology, wherein the inkjet printhead components required to realize this full-color printing technology include: A compact structure with separate or integrated installation of the molding material print head, the support material print head, the color ink print head, and the infusion tubes connecting each print head to the molding ink, color ink cartridge, and support storage box. The necessary mechanical and electronic components for realizing the present invention also include: a mechanical device for driving the inkjet printhead, a height-adjustable printing platform, a transparent substrate, an electronic control system, a support housing, and a curing light source including: a common surface light source, a laser scanning or LCD / DLP surface array light source; the specific connection relationship of each component includes: a mechanical system for maintaining the relative movement of the printing platform device and the transparent substrate by changing the distance, or the transparent substrate by lifting and lowering, and a mechanical system for maintaining the controllable two-dimensional relative movement between the inkjet printhead and the transparent substrate; The conventional operating procedure followed by this invention is as follows: First, the printer's components undergo a general initialization procedure, including the printing platform rising and resetting to maintain its distance from the transparent substrate. The printing process involves the electronic control system instructing the mechanical system to move the inkjet printhead assembly and spray a pre-edited slice of the object's content onto the transparent substrate. If pre-curing is required, a pre-curing process is performed on the slice on the transparent substrate: after pre-curing the slice, the electronic and mechanical systems drive the printing platform to descend closer to the transparent substrate and stop at a distance maintaining a preset layer thickness, thus aligning the slice with the printing platform or the cross-section of the printed object. Final curing then occurs. After final curing, the slice is cured and bonded to the cut surface of the printed object, increasing its thickness by one slice. This process is repeated continuously: slice preparation – slice pre-curing and alignment – ​​transfer curing. The printed object is gradually increased in height on the printing platform, ultimately completing the printing of the entire object. Its characteristics are: This printing technology requires a combination of at least one of the following three processes: adaptive slicing adaptation, pre-curing treatment, and sub-slice insertion adhesive spraying: *Adaptive slicing process: The adaptive slice structure: The thickness of the adaptive slice is 1%-50% greater than the preset layer thickness, and the surface of the slice retains a solid structure of 0.2mm-50mm; under the solid structure of the above-mentioned surface layer of the slice, a honeycomb pore structure is designed. The honeycomb pore structure is a collection of numerous cavities surrounded by conventional crisscrossing grid walls. The ratio of the total area of ​​the grid walls and cavities determines the filling rate of the printed object, and includes the color shell structure of the adaptive slice. *Pre-curing process: Necessity of Pre-curing: During the implementation of the adaptive slicing principle, the deformation caused by the printing platform applying pressure to the current slice layer expands in all directions. Since some of this expansion inevitably points towards the surface of the printed object, it will inevitably affect the dimensional appearance of the printed object. Therefore, a pre-curing principle is needed for the current color shell layer or the portion of the current color shell layer with lower viscosity. Pre-curing methods: Selective pre-curing or full pre-curing: When performing selective pre-curing, before the printing platform has driven into contact with the printed object, laser scanning or LCD / DLP array light sources are used to selectively pre-cur the surface of the printed object, within a depth range of 0.2mm-50mm from the surface. Curing within the surrounding area increases the strength of the material around the current slice layer. When the printing platform drives the printed object to contact the current slice layer, the increased hardness of the surrounding material greatly prevents the uncured material from expanding towards the surface, forcing the uncured material in the current slice layer to expand into the cavities of the internal honeycomb structure, thus achieving the goal of stabilizing the appearance shape. Alternatively, a uniform pre-curing method can be used to cure the entire slice, with a higher curing exposure dose on the surface. The degree of pre-curing is divided into semi-curing or full curing. Semi-curing refers to a relatively small exposure dose without complete curing, allowing the current slice layer to retain a certain degree of softness and fluidity. *Sub-slice insertion and adhesive spraying process: To achieve a strong bond between the current slice layer and the printed object, selective adhesive spraying is performed. After the pre-cured, semi-hardened current slice, selective or full-section adhesive spraying is applied to the surface of the current slice. Alternatively, selective adhesive spraying can be applied to the cut surface of the already formed printed object or to the surface of the current slice. The adhesive can be a UV-curable adhesive or the corresponding color ink used in the current slice, applied in a thin layer to cure the bond. The sprayed content is either a layer of transparent adhesive or a layer of printed content in the same color as the current slice. The thickness of the adhesive layer is 1%-80% of the thickness of the current slice. The purpose of adhesive spraying is to strengthen the bond while increasing printing efficiency and preventing excessive deformation of the printed slice.

2. The process configuration according to claim 1, characterized in that: Includes three types of process combinations: The first type of process combination consists of, in order: inkjet generation of adaptive slicing process, adaptive slicing pre-curing process, selective insertion of sub-slices adhesive spraying process; and finally, slicing transfer and curing process. Adaptive tiling is performed during 3D modeling or generated within the tiling software workflow; The second type of process combination consists of: conventional inkjet wafer process, wafer pre-curing process, selective insertion of sub-wafer adhesive spraying process; and finally, pre-cured wafer transfer and curing process. The third type of process combination consists of, in order: inkjet printing to generate adaptive slicing process, and finally adaptive slicing transfer and curing process.

3. The adaptive slicing color shell structure according to claim 1, characterized in that: The outermost layer of the colored shell corresponds to the surface of the printed object, and the printed object only needs surface coloring. From the surface inwards, there are: a transparent shell, a color mixing layer, a base color layer, and a structural layer. Each of these layers is formed by inkjet printing of molding ink and color ink cartridges. The characteristics are a transparent shell, a color mixing layer, a base color layer, and a structural layer. In addition, the colored shell structure includes the following 6 combinations: a 3-layer combination of transparent shell + colored layer + base color layer; a 2-layer combination of colored layer + base color layer; a 2-layer combination of transparent shell + colored layer; a 2-layer combination of transparent shell + base color layer; a 1-layer combination of a single base color layer; and a 1-layer combination of a single colored layer.

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