Additive manufacturing system and additive manufacturing method

Abstract

Disclosed in the present application is a three-dimensional printing method for manufacturing a target object. The three-dimensional printing method comprises: providing a first material container having a first printing region, and irradiating the first printing region to solidify the first material and form a first portion of a first layer, the first portion of the first layer having a first thickness; and providing a second material container having a second printing region, and irradiating the second printing region to solidify the second material and form a second portion of the first layer, the second portion of the first layer having a second thickness. During irradiation, the liquid levels of the first material container and the second material container are maintained at 40 μm-950 μm, and are at least 1.2 times the second thickness. This at least facilitates reducing the risk of color mixing of materials in the containers.

Description

Additive manufacturing systems and additive manufacturing methods

[0001] This application claims priority to Chinese Patent Application No. 2024115531577, filed on November 1, 2024, entitled "3D Printing Method and System for Manufacturing Target Objects," the entire contents of which are incorporated herein by reference; and to Chinese Patent Application No. 2024118433580, filed on December 13, 2024, entitled "Additive Manufacturing System and Additive Manufacturing Method," the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of additive manufacturing, and more specifically, to an additive manufacturing system and an additive manufacturing method. Background Technology

[0003] Additive manufacturing (or 3D printing) technology creates three-dimensional entities by layering data from a three-dimensional model of an object. Additive manufacturing includes technologies such as FDM, SLS, SLA, DLP, and LCD. Photopolymerization technologies, represented by DLP and LCD, can manufacture products with high precision.

[0004] Currently, there is an increasing demand for products that require multiple materials; for example, the outer edges of a product may require a softer material, while the interior may require a harder material. Constructing a target object using multiple different materials is challenging; for instance, when using various materials, the materials in different containers holding different materials can gradually become contaminated by other materials. Therefore, an improved additive manufacturing system is needed. Summary of the Invention

[0005] This application provides a 3D printing method for manufacturing a target object. The 3D printing method includes: providing a first material container having a first printing area; irradiating the first printing area to cure a first material and form a first portion of a first layer, the first portion of the first layer having a first thickness; providing a second material container having a second printing area; irradiating the second printing area to cure a second material and form a second portion of the first layer, the second portion of the first layer having a second thickness; wherein, during irradiation, the liquid level in the first and second material containers is maintained at 40 μm to 950 μm, and is at least 1.2 times the second thickness. This at least helps to reduce the risk of material color mixing in the containers.

[0006] In some embodiments, the liquid level in the first material container and the second material container is 1.5 to 20 times the second thickness, preferably 2 to 8 times, more preferably 3 to 7 times, and even more preferably 4 to 6 times. For example, 1.8 to 8 times, for example 2 to 6 times, for example 3 to 5 times.

[0007] In some embodiments, the liquid levels in the first and second material containers are 100 μm to 800 μm, for example 120 μm to 700 μm, preferably 150 μm to 600 μm, more preferably 180 μm to 500 μm, and even more preferably 200 μm to 400 μm. This at least helps to reduce the number of air bubbles in the solidified object.

[0008] In some embodiments, a second portion of the first layer is formed on a first portion of the first layer.

[0009] In some embodiments, along the construction direction of the target object or the Z-axis direction, the first portion of the first layer at least partially overlaps with the second portion of the first layer.

[0010] In some embodiments, the first thickness of the first portion of the first layer is equal to the second thickness of the second portion of the first layer.

[0011] In some embodiments, the second thickness of the second portion of the first layer is greater than the first thickness of the first portion of the first layer.

[0012] In some embodiments, the three-dimensional printing method further includes: radiating a first printing area to cure a first material to form a first portion of a second layer on a first portion of a first layer, such that the total thickness of the first portion of the first material is greater than the total thickness of the second portion of the second material; and then radiating a second printing area to cure a second material to form a second portion of the second layer on a second portion of the first layer, such that the total thickness of the second portion of the second material is greater than the total thickness of the first portion of the first material.

[0013] In some embodiments, the 3D printing method further includes cleaning the cured portion of the target object.

[0014] In some embodiments, cleaning includes at least one of the following: rotating the target object, wiping the target object, applying an airflow to the target object, or surrounding the target object with an adsorption element.

[0015] In some embodiments, after the first portion of the first layer is formed, the cured portion of the target object is cleaned; and / or, after the second portion of the first layer is formed, the cured portion of the target object is cleaned.

[0016] In some embodiments, the cured portion of the target object includes: a base portion; and at least one of a first portion or a second portion of a first layer adhered to the base portion.

[0017] This application also provides a three-dimensional printing system for manufacturing a target object. The three-dimensional printing system includes: a first material container that includes a first printing area and contains a first material; a second material container that includes a second printing area and contains a second material different from the first material; an optical unit configured to project light onto the first printing area or the second printing area; and a processor configured to determine the thickness of the portion to be cured; wherein, during the projection of light, the liquid level of the first material container and the second material container is maintained at 40 μm to 950 μm, and is more than 1.2 times the thickness of the portion to be cured.

[0018] This application provides an additive manufacturing system comprising: a first carrier device configured to carry a first material; a forming platform configured to move along a first direction to approach or move away from the first carrier device; a first actuator for the first carrier device movable between a first height level and a second height level, wherein, at the first height level, the first actuator is configured to move along a second direction perpendicular to the first direction to allow at least a portion of the first material carried by the first carrier device to be held at a first predetermined height; at the second height level, different from the first height level, the first actuator is movable along a second direction; and an optical unit configured to project light onto the first material at the first predetermined height to allow the first material to cure based on a preset pattern. The first actuator allows for a variety of uses.

[0019] In some embodiments, the first support device is formed as a plate-shaped element or a box-shaped element.

[0020] In some embodiments, when the first support device is formed as a plate-shaped element, the first actuator is configured to move in a second direction so that all the first material carried by the first support device is held at a first predetermined height.

[0021] In some embodiments, the first carrier includes at least one collection container configured to collect the first material propelled by the first actuator.

[0022] In some embodiments, the additive manufacturing system includes at least one collection container configured to be spaced apart from the first carrier and to collect first material propelled by the first actuator.

[0023] In some embodiments, when the first support device is formed as a box-shaped element, the first actuator is configured to move in a second direction such that a portion of the first material carried by the first support device is held at a first predetermined height, and the remainder of the first material carried by the support device is above the first predetermined height.

[0024] In some embodiments, the first actuator includes a lower portion configured to prevent the flow of first material through the lower portion.

[0025] In some embodiments, the additive manufacturing system further includes a first feeding mechanism configured to supply a first material to a first support device.

[0026] In some embodiments, the first feeding mechanism is configured to be stationary or movable relative to the first carrying device.

[0027] In some embodiments, the second altitude level is higher than the first altitude level; or the second altitude level is lower than the first altitude level.

[0028] In some embodiments, the first actuator is configured to move between a first height level, a second height level, and a third height level, wherein the first height level is between the second height level and the third height level.

[0029] In some embodiments, the first predetermined height is 50μm to 1000μm, for example 100μm to 800μm, for example 200μm to 500μm, for example 300μm to 400μm.

[0030] In some embodiments, the additive manufacturing system further includes a cleaning unit configured to separate uncured first material adhering to a cured object on a molding platform from the cured object.

[0031] In some embodiments, the cleaning unit includes at least one of an airflow assembly, a wiping assembly, an adsorption assembly, a cleaning container, a spraying assembly, or a heating assembly.

[0032] In some embodiments, the additive manufacturing system further includes a second support device configured to carry a second material, wherein the second material is different from the first material.

[0033] In some embodiments, the additive manufacturing system further includes a second actuator for a second support device, the second actuator being movable to different height levels along a first direction.

[0034] This application also provides an additive manufacturing method, comprising: moving a molding platform along a first direction to approach or move away from a first support device; maintaining a first actuator at a first height level; when the first actuator is at the first height level, driving the first actuator to move along a second direction perpendicular to the first direction, so that at least a portion of the first material carried by the first support device is maintained at a first predetermined height; using an optical unit to project light onto the first material at the first predetermined height, so as to allow the first material to solidify based on a preset pattern; and driving the first actuator to move along the first direction to a second height level different from the first height level.

[0035] In some embodiments, the additive manufacturing method further includes: driving the first actuator to move along a second direction when the first actuator is at a second height level, so that at least a portion of the first material carried by the first carrier is maintained at a second predetermined height, the second predetermined height being lower than the first predetermined height; driving the first actuator to move along a first direction from the second height level to the first height level; and using an optical unit to project light onto the first material at the first predetermined height, so as to allow the first material to cure based on a new preset pattern.

[0036] In some embodiments, the additive manufacturing method further includes: driving the first actuator to move in a second direction when the first actuator is at a second height level, so that at least a portion of the first material carried by the first carrier is held at a third predetermined height, the third predetermined height being higher than the first predetermined height; and using an optical unit to project light onto the first material at the third predetermined height to allow the first material to cure based on a new preset pattern.

[0037] In some embodiments, the additive manufacturing method further includes: after curing the first material, moving at least one of a molding platform and a second carrier device carrying the second material to align the molding platform with the second carrier device; and using an optical unit, projecting light onto the second material carried by the second carrier device to cure the second material based on a new preset pattern.

[0038] The additive manufacturing system provided in this application is advantageous for obtaining high-quality objects using multi-material photopolymerization printing. The first actuator, capable of operating at multiple heights, helps maintain different liquid levels, thereby achieving the desired printing effect.

[0039] This application also provides an additive manufacturing system comprising: a molding platform movable along a first direction; a first carrier configured to carry a first material; a second carrier configured to carry a second material different from the first material; an optical unit configured to project light to allow the first material or the second material to cure based on a preset pattern; and a cleaning unit configured to separate uncured material adhering to a cured object on the molding platform from the cured object.

[0040] In some embodiments, the cleaning unit includes at least one of an airflow assembly, a wiping assembly, an adsorption assembly, a cleaning container, a spraying assembly, or a heating assembly.

[0041] In some embodiments, the airflow assembly is configured to apply a positive or negative pressure airflow to the solidified object.

[0042] In some embodiments, the adsorption component includes a sponge or a fabric.

[0043] In some embodiments, the cleaning container is configured to contain cleaning agent.

[0044] In some embodiments, the absorbent layer is made of a soft, porous material.

[0045] This application also provides an additive manufacturing system comprising: a molding platform movable along a first direction; a first carrier configured to carry a first material; a second carrier configured to carry a second material different from the first material; an optical unit configured to project light to allow the first material or the second material to cure based on a preset pattern; and a cleaning unit configured to separate uncured material adhering to a cured object on the molding platform from the cured object, wherein the cleaning unit includes at least one absorbent layer configured to allow uncured material to flow into pores in the absorbent layer.

[0046] In some embodiments, at least one absorbent layer includes a first absorbent layer and a second absorbent layer, the first absorbent layer and the second absorbent layer being composed of different porous materials, such as a soft porous material.

[0047] In some embodiments, the additive manufacturing system further includes a heating element configured to raise the temperature of at least one absorption layer.

[0048] In some embodiments, the additive manufacturing system further includes a pressure assembly configured to apply an airflow to blow away uncured material from a cured object and configured to facilitate the flow of uncured material in the pores of the absorbent layer.

[0049] In some embodiments, the additive manufacturing system further includes a negative pressure assembly configured to force airflow and uncured material to flow through at least one absorbent layer.

[0050] In some embodiments, the positive or negative pressure assembly is equipped with a collection container configured to collect material flowing through at least one absorbent layer.

[0051] In some embodiments, the absorbent layer is removable or replaceable.

[0052] In some embodiments, the additive manufacturing system further includes a conveying mechanism for conveying the absorbent layer.

[0053] This application also provides an additive manufacturing method, which includes: projecting light to solidify and adhere a first material carried by a first carrier device to a molding platform; using a cleaning unit to separate uncured material on a cured object adhered to the molding platform from the cured object; and projecting light to solidify and adhere a second material carried by a second carrier device to the molding platform.

[0054] The additive manufacturing system provided in this application is advantageous for obtaining high-quality objects using multi-material photopolymerization printing. The cleaning unit enables the separation of uncured material adhering to the cured object on the forming platform from the cured object, thereby reducing the risk of mixing of the uncured first type of material with the second type of material carried by the carrier device in subsequent steps. Attached Figure Description

[0055] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and therefore should not be regarded as a limitation on the scope of protection.

[0056] Figures 1A-1C show a target printed object according to a certain embodiment;

[0057] Figure 2 shows a slice diagram of the target object in the first height section;

[0058] Figure 3 shows a slice diagram of the target object in the second height section;

[0059] Figure 4 shows a schematic diagram of a portion of the additive manufacturing system;

[0060] Figures 5A-5G show schematic diagrams of sections involving three materials for manufacturing a target object according to an embodiment;

[0061] Figures 6A-6I show schematic diagrams of sections involving three materials for manufacturing a target object according to another embodiment;

[0062] Figure 7 illustrates an embodiment for forming an object comprising two materials;

[0063] Figure 8 shows a schematic diagram of a portion of another additive manufacturing system;

[0064] Figure 9A shows a schematic diagram of an object obtained by solidifying material in a container with a first liquid level.

[0065] Figure 9B shows a schematic diagram of an object obtained by curing material in a container with a second liquid level, which is greater than the first liquid level in Figure 8A.

[0066] Figure 10 shows a schematic diagram of a printout containing two printing materials;

[0067] Figure 11 shows a schematic diagram of a printout containing two printing materials;

[0068] Figure 12 shows the support device of the additive manufacturing system;

[0069] Figure 13 shows the cleaning unit of the additive manufacturing system;

[0070] Figure 14 shows a schematic diagram of a portion of the additive manufacturing system;

[0071] Figure 15 shows a schematic diagram of a portion of the additive manufacturing system;

[0072] Figure 16 shows a schematic diagram of a portion of the additive manufacturing system;

[0073] Figure 17 illustrates some embodiments for maintaining the printing liquid level;

[0074] Figure 18 illustrates some embodiments for maintaining the printing liquid level;

[0075] Figure 19 illustrates some embodiments of maintaining the printing liquid level;

[0076] Figure 20 illustrates some embodiments for maintaining the printing liquid level;

[0077] Figure 21 illustrates some embodiments for maintaining the printing liquid level;

[0078] Figure 22 illustrates some embodiments for maintaining the printing liquid level;

[0079] Figures 23A-23C illustrate some embodiments of maintaining the printing liquid level;

[0080] Figures 24A-24D illustrate some embodiments of the cleaning unit;

[0081] Figures 25A-25D illustrate a portion of an additive manufacturing system according to some embodiments; and

[0082] Figure 26 shows some embodiments of the cleaning unit.

[0083] In the accompanying drawings, some of the same or similar reference numerals represent some of the same or similar elements or components, and the scale of each part in the drawings is not necessarily true, but rather schematic. Detailed Implementation

[0084] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all of them. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application. The various elements, parts, and components in the embodiments provided in the present application can be combined with each other to form new embodiments when they do not contradict each other, and these should fall within the scope of protection of the present application.

[0085] The terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, or system, product, or apparatus that comprises a series of steps is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0086] Figures 1A-1C illustrate a target printed object according to one embodiment. As shown in Figures 1A-1B, the printed object 100 to be formed includes three parts 120, 140, and 160 made of "different types" of materials. The first part 120 is made of a first type of material A, the second part 140 is made of a second type of material B, and the third part 160 is made of a third type of material C.

[0087] In this paper, "different types of materials" refers to any two types of materials having at least one different property. For example, objects formed by curing materials A and B under light radiation have different optical properties, such as their ability to absorb light and their light transmittance. Another example is that objects formed by curing materials A and B under light radiation have different physical properties, such as their color, elasticity, and yield strength. Yet another example is that materials A and B have different chemical properties, such as having different compositions.

[0088] In Figure 1C, the target object 100 is further divided into three height segments Z1, Z2, and Z3. For example, when manufacturing the target object 100 using photopolymerization technology, such as DLP, material B is first cured in the first height segment Z1, then materials A, B, and C are cured in the second height segment Z2, and finally materials A and C are cured in the third height segment Z3.

[0089] In the first height segment Z1, the target object 100 comprises only a portion made of material B. In the second height segment Z2, the target object 100 has a portion made of material A, a portion made of material B, and a portion made of material C, wherein the portion made of material B is located between the portions made of material A and material C, and contacts them in the horizontal direction (or perpendicular to the height). In the third height segment Z3, the target object 100 has a portion made of material A and a portion made of material C, and they are spaced apart from each other in the horizontal direction.

[0090] Figure 2 shows a schematic diagram of a slice of the target object in the first height segment Z1. The target object in the first height segment Z1 consists of only a single material B, and a portion 240 of the target object can be obtained by continuously curing to form multiple layers 241.

[0091] A portion 240 of the target object 100 is divided into multiple layers 241, for example, 200 layers. Each layer 241 has the same thickness, for example, 30 μm; or, it may have different thicknesses, for example, some of the multiple layers 241 have a thickness of 30 μm and some have a thickness of 50 μm. A larger thickness is beneficial for speeding up the printing of the target object, while a smaller thickness is beneficial for obtaining an object with better surface quality.

[0092] Figure 3 shows a schematic cross-section of the target object in the second height segment. The target object in the second height segment Z2 comprises a first segment made of material A, a second segment made of material B, and a third segment made of material C. To manufacture the target object in the second height segment (which is formed on the portion of the target object in the first height segment), the target object is layered to facilitate subsequent manufacturing.

[0093] Although not shown, the target object in the third height segment Z3 comprises a first segment made of material A and a second segment made of material C. To manufacture the target object in the third height segment (which is formed on the portion of the target object in the second height segment), the target object is layered to facilitate subsequent manufacturing.

[0094] Figure 4 shows a schematic diagram of a portion of an additive manufacturing system. The additive manufacturing system 480 or 3D printing apparatus 480 includes a forming platform 481 for adhering a target object (as shown in Figures 1A-1C). Figure 4 shows a portion 442 of the target object (made of material B) that has been cured and adhered to the forming platform 481. In the embodiment shown in Figure 4, a plurality of supports 448, also made of material B, are formed to support this portion 442. The 3D printing apparatus 480 also includes a carrier device 483 for carrying or containing material B and an optical unit or radiation device 485 for projecting light onto the carrier device 483. For example, the optical unit 485 emits ultraviolet light of a predetermined wavelength (e.g., 385 nm or 405 nm) that penetrates at least a partially transparent bottom of the carrier device 483, causing the printing material (e.g., photosensitive resin) carried by the carrier device 483 to cure. The carrier device 483 is provided with a film, for example, a film with a light transmittance of 80% to 95%. In Figure 4, the solidified target object 442 leaves the support device 483 containing material B.

[0095] Figure 5A shows a schematic diagram of a portion of an additive manufacturing system. For simplicity, optical units and some support devices are omitted. A portion 540 of a cured target object, made of material B, is adhered to a forming platform 581 of the additive manufacturing system. The additive manufacturing system drives at least one of the forming platform 581 or the support device 586 via a drive mechanism (not shown) to align the forming platform 581 with the support device 586, thereby allowing material C carried by the support device 586 to be cured and adhered to the forming platform 581 or the cured material thereon. Figure 5A shows a first portion 561 made of material C adhered to the portion 540 of the target object.

[0096] Figure 5B shows a schematic diagram of a portion of an additive manufacturing system. A molding platform 581 of the additive manufacturing system has portions 540, 561 of a cured target object adhered to it. The additive manufacturing system drives at least one of the molding platform 581 or the carrier device 584 via a drive mechanism (not shown) to align the molding platform 581 with the carrier device 584, thereby allowing material B carried by the carrier device 584 to be cured. Figure 5B shows a second portion 541 made of material B, which is adhered to a portion 540 of the target object and contacts a first portion 561 made of material C. In the embodiment shown in Figure 5B, the first portion 561 and the second portion 541 have the same thickness and the same top or bottom surface. In other words, the first portion 561 and the second portion 541 completely overlap along the build direction or Z-axis direction of the target object or the stacking direction of the layers of the target object. The first portion 561 and the second portion 541 can be understood as two portions of the same layer of the target object. Those skilled in the art will understand that both the first portion 561 and the second portion 541 are formed based on the surface exposure of the pattern, and therefore each of the first portion 561 and the second portion 541 of the first layer of the entity is understood to have a top surface and a bottom surface with equal areas and a side surface extending perpendicular to the top surface and the bottom surface.

[0097] Figure 5C shows a schematic diagram of a portion of an additive manufacturing system. A molding platform 581 of the additive manufacturing system has several portions 540, 561, 541 of a cured target object adhered to it. The additive manufacturing system drives the molding platform 581 and / or the carrier device 582 via a drive mechanism (not shown) to align the molding platform 581 with the carrier device 582, thereby allowing material A carried by the carrier device 582 to be cured. Figure 5C shows a third portion 521 made of material A, which is adhered to a portion 540 of the target object and contacts the first portion 541 made of material B. In the embodiment shown in Figure 5C, the first portion 561, the second portion 541, and the third portion 521 have the same thickness and the same top or bottom surface. In other words, the first portion 561, the second portion 541, and the third portion 521 completely overlap along the build direction or Z-axis direction of the target object or the stacking direction of the layers of the target object. Part 1, Part 2, and Part 3, 561, can be interpreted as three parts of a layer 51 of the target object.

[0098] Figures 5D-5F illustrate some states for manufacturing the target object. The target object includes a second layer 52 adhered to a first layer 51, the second layer 52 comprising a first portion 562 made of material C (preferably as shown in Figure 5D), a second portion 542 made of material B (preferably as shown in Figure 5E), and a third portion 522 made of material A (preferably as shown in Figure 5F).

[0099] Figures 5D-5F illustrate three states cured in a specified order. Specifically, material C is first cured to form the first portion 562, then material B is cured to form the second portion 542, and finally material A is cured to form the third portion 542. In other embodiments, these three portions are formed in a different order. For example, material C is first cured to form the first portion 562, then material A is cured to form the third portion 542, and finally material B is cured to form the second portion 542. The order in which these three portions in the same layer are formed can be arbitrary.

[0100] Figure 5G shows the second height segment of the formed target object. In Figure 5G, the second height segment Z2 includes multiple layers 51, 52, ..., 58, each layer comprising three parts made of three different materials. For example, the last layer 58 includes a first part 568 made of material C, a second part 548 made of material B, and a third part 528 made of material A.

[0101] The embodiments shown in Figures 5A-5G demonstrate the manufacture of objects having different portions composed of different materials within the same layer. It is understood that the multiple layers of the second height segment Z2 may have the same or different thicknesses. For example, the thickness of the first layer 51 is 50 μm, the thickness of the second layer 52 is 50 μm, and the thickness of the third layer 53 is 60 μm. The thickness of each layer in the second height segment can be, for example, 20 μm–300 μm, 30 μm–200 μm, 40 μm–150 μm, 50 μm–100 μm, 60 μm, 70 μm, 80 μm, 80 μm, 82 μm, 83 μm, 85 μm, or 90 μm.

[0102] To manufacture a second height segment of the target object, this disclosure also provides an alternative, as shown in Figures 6A-6I. Figure 6A shows a schematic diagram of a portion of an additive manufacturing system. For simplification, optical units and some support devices are omitted. A portion 640 of the target object, made of material B, is adhered to a forming platform 681 of the additive manufacturing system 600. The additive manufacturing system drives at least one of the forming platform 681 or the support device 686 via a drive mechanism (not shown) to align the forming platform 681 with the support device 686, thereby allowing the material C carried by the support device 686 to be cured. Figure 6A shows a first portion 661 made of material C, which is adhered to the portion 640 of the target object and has a first thickness t1.

[0103] Figure 6B shows a schematic diagram of a portion of an additive manufacturing system. A molding platform 681 of the additive manufacturing system has portions 640, 661 of a cured target object adhered to it. The additive manufacturing system drives at least one of the molding platform 681 or the carrier device 684 via a drive mechanism (not shown) to align the molding platform 681 with the carrier device 684, thereby allowing the material B carried by the carrier device 684 to be cured. Figure 6B shows a second portion 641 made of material B, which is adhered to a portion 640 of the target object and in contact with a first portion 661 made of material C. The second portion 641 has a second thickness t2. Specifically, the first portion 661 and the second portion 641 have top surfaces of the same height (i.e., the surfaces in contact with the cured portion 640), but bottom surfaces of different heights opposite to the top surfaces.

[0104] As shown in Figure 6B, the second thickness t2 of the second portion 641 is greater than the first thickness t1 of the first portion 661. In other words, the second portion 641 partially overlaps with the first portion 661 along the construction direction, Z-axis direction, or stacking direction of the target object's layers. For example, the first portion 661 and the second portion 641 have top surfaces of the same height, the first thickness t1 is 40 μm, and the second thickness t2 is 100 μm. Therefore, along the construction direction, Z-axis direction, or stacking direction of the target object's layers, the overlap length between the second portion 641 and the first portion 661 is 40 μm, and the non-overlap length is 60 μm. Those skilled in the art will understand that the forming platform of an additive manufacturing system can be driven to move along a vertical direction (or the stacking direction of the sliced ​​layers), but errors in the accuracy of the movement are unavoidable. For example, the positioning accuracy of the drive device used to drive the forming platform or carrier device to move along a vertical direction is 25 μm / 300 mm.

[0105] In one example, the material C carried by the support device 686 is cured to form a first portion 661 with a thickness of 50 μm. The molding platform 681 carrying the first portion 661 is raised 300 mm and then moved horizontally (e.g., translated or rotated) from a position aligned with the support device 686 to a position aligned with the support device 684. The molding platform 681 then descends 300 mm to prepare for curing a second portion 641 with a thickness of 50 μm. Due to the positioning accuracy (25 μm / 300 mm) of the drive device used to drive the molding platform to move vertically, the descended molding platform 681 may actually descend 20 μm more than the ideal value of 300 mm. This would cause the cured first portion 661 to contact the flexible film of the support device 684 and move downwards by 20 μm. Alternatively or additionally, there is an installation error (e.g., 0–50 μm, e.g., 20 μm) in the height direction between the support device 686 and the support device 684. The lowered molding platform 681 normally descends the ideal value of 300 mm; however, the cured first portion 661 contacts the flexible film of the support device 684 and moves downwards by 20 μm. This movement occurs repeatedly during the manufacturing of the second height section of the target object, increasing the risk of the cured portion being damaged by the downward pressure on the flexible film of the support device. On the other hand, the flexible film of the support device 684 is repeatedly pressed down by the cured portion and pulled upwards when a new cured portion is peeled off, which reduces the film's lifespan.

[0106] The aforementioned risk is mitigated when the second thickness t2 of the second portion 641 is greater than the first thickness t1 of the first portion 661. For example, the material C carried by the support device 686 is cured to form a first portion 661 with a thickness of 50 μm. The molding platform 681 carrying the first portion 661 is raised 300 mm and then moved horizontally (e.g., translated or rotated) from a position aligned with the support device 686 to a position aligned with the support device 684. The molding platform 681 then descends 299.9 mm to prepare for curing the second portion 641 with a thickness of 100 μm. Due to the positioning error (e.g., 25 μm / 300 mm) of the drive device that drives the molding platform to move in the vertical direction, the descending molding platform 681 may actually descend 20 μm more than the ideal value of 299.9 mm. This will result in the cured first portion 661 descending 20 μm more, at which point the first portion 661 is 30 μm away from the flexible film of the support device 684, but will not contact the flexible film of the support device. Alternatively or additionally, due to the installation error (e.g., 20 μm) in the height direction between the support device 686 and the support device 684, after the forming platform 681 descends by the ideal value of 299.9 mm, the first part 661 is 30 μm (not 50 μm) away from the flexible membrane of the support device 684, but will not contact the flexible membrane of the support device.

[0107] Figure 6C shows a schematic diagram of a portion of an additive manufacturing system. A molding platform 681 of the additive manufacturing system has portions 640, 661, and 641 of a solidified target object adhered to it. The additive manufacturing system drives at least one of the molding platform 681 or the carrier device 682 via a drive mechanism (not shown) to align the molding platform 681 with the carrier device 682, thereby allowing material A carried by the carrier device 682 to solidify. Figure 6C shows a third portion 621 made of material A, which is adhered to a portion 640 of the target object and in contact with a second portion 641 made of material B. The third portion 621 has a third thickness t3. Specifically, the first portion 661, the second portion 641, and the third portion 621 have top surfaces of the same height (i.e., the surfaces in contact with the solidified portion 640) but bottom surfaces of different heights opposite to the top surfaces. Similarly, the third thickness t3 of the third portion 621 is greater than the second thickness t2 of the second portion 641.

[0108] Those skilled in the art will understand that the first part 661, the second part 641 and the third part 621 are all formed based on patterned surface exposure. Therefore, any one of the first part 661, the second part 641 and the third part 621 of the first layer 61 of the target object can be understood as having a top surface and a bottom surface with equal areas, and having a side surface extending perpendicular to the top surface and the bottom surface.

[0109] The first part 661, the second part 641, and the third part 621 can be interpreted as three portions of a layer 61 of the target object. This layer 61 is a layer that includes the solidified product. The first part 661, the second part 641, and the third part 621 of the first layer 61 of the target object have different thicknesses. According to the formation order, the thickness of the later formed portion is greater than the thickness of the earlier formed portion, which can reduce various risks caused by positioning accuracy, such as vertical movement. In other embodiments, curing or printing can be performed in the following order: first, curing material C to form the first part 661 with a first thickness t1', then curing material A to form the third part 621 with a third thickness t3' (t3' > t1'), and finally curing material B to form the second part 641 with a second thickness t2' (t2' > t3').

[0110] Figures 6D-6F illustrate some states used in manufacturing the target object. The target object includes a second layer 62 adhered to the first layer 61. Similar to the first layer, the second layer 62 has three regions of different thicknesses. The second layer 62 includes a first portion 662 made of material C (ideally as shown in Figure 6D), a second portion 642 made of material B (ideally as shown in Figure 6E), and a third portion 622 made of material A (ideally as shown in Figure 6F).

[0111] As shown in Figure 6D, the first portion 662 of the second layer 62 has a predetermined thickness t4, such that the total thickness of the first portion composed of material C (i.e., the sum of the first portions 661 of the first layer 61 and the first portions 662 of the second layer 62) is greater than the total thickness of the third portion composed of material A. Of course, the total thickness t3 of the third portion 621 composed of material A is greater than the total thickness t2 of the second portion 641 composed of material B. In some embodiments, the predetermined thickness t4 is equal to the third thickness t3. In some embodiments, the predetermined thickness t4 is not equal to the third thickness t3, but t1 + t4 > t3.

[0112] As shown in Figure 6E, the second portion 642 of the second layer 62 has a predetermined thickness t5, such that the total thickness of the second portion composed of material B (i.e., the sum of the second portions 641 of the first layer 61 and the second portions 642 of the second layer 62) is greater than the total thickness of the first portion composed of material C (i.e., the sum of the first portions 661 of the first layer 61 and the first portions 662 of the second layer 62). In some embodiments, the predetermined thickness t5 of the second portion 642 is equal to the predetermined thickness t4 of the first portion 662, which is beneficial for the design of process parameters during the slicing process in 3D printing. In some embodiments, the predetermined thickness t5 of the second portion 642 is not equal to the predetermined thickness t4 of the first portion 662, but t2+t5>t1+t4.

[0113] As shown in Figure 6F, the third portion 622 of the second layer 62 has a predetermined thickness t6, such that the total thickness of the third portion composed of material A (i.e., the sum of the third portion 621 of the first layer 61 and the third portion 622 of the second layer 62) is greater than the total thickness of the second portion composed of material B (i.e., the sum of the second portion 641 of the first layer 61 and the second portion 642 of the second layer 62). In some embodiments, the predetermined thickness t6 of the third portion 622 is equal to the predetermined thickness t4 of the first portion 662, which is beneficial for the design of process parameters during the slicing process in 3D printing. In some embodiments, the predetermined thickness t6 of the third portion 622 is not equal to the predetermined thickness t4 of the first portion 662, but t3 + t6 > t2 + t5.

[0114] In the embodiments shown in Figures 6A-6F, the thicknesses of these portions of the first and second layers can be configured with various parameters. For example, the first thickness t1 of the first portion 661 of the first layer 61 is 1%-90% of the third thickness t3 of the third portion 621 of the first layer 61, preferably 30%-70%, more preferably 40%-60%; the second thickness t2 (t2 > t1) of the second portion 641 of the first layer 61 is 10%-90% of the third thickness t3 of the third portion 621 of the first layer 61, preferably 30%-70%, more preferably 40%-66%.

[0115] As an example, the first thickness t1 of the first part 661 of the first layer 61 is one-third of the third thickness t3 of the third part 621 of the first layer 61, and the second thickness t2 of the second part 641 of the first layer 61 is two-thirds of the third thickness t3 of the third part 621 of the first layer 61.

[0116] As an example, the thickness t4 of the first part 662 of the second layer 62 is equal to the thickness t5 of the second part 642 of the second layer 62, and the thickness t5 of the second part 642 of the second layer 62 is equal to the thickness t6 of the third part 622 of the second layer 62. This is beneficial for the design of process parameters in the slicing process in 3D printing.

[0117] As an example, the thickness t4 of the first part 662 of the second layer 62 is equal to the third thickness t3 of the third part 621 of the first layer 61, and t4 = t5 = t6, which makes the total thickness (t3 + t6) of the third part composed of material A twice the third thickness (t3).

[0118] Figure 6G illustrates a third layer for manufacturing the second height segment of the target object. The third layer 63 is adhered to the second layer 62. Similar to the second layer 62, the third layer 63 has three regions of different thicknesses. The third layer 63 includes a first portion 663 made of material C, a second portion 643 made of material B, and a third portion 623 made of material A. The second height segment Z2 of the target object is defined by an initial axis L1 and an end axis L2. In the embodiment shown in Figure 6G, the third layer 63 has reached the end axis L2, meaning that printing cannot continue in the manner in which the second layer 62 and the third layer 63 are formed because the thickness of the portion to be cured in the second height segment is insufficient.

[0119] During the formation of the remaining unformed portion in the second height section, there is a risk that the third portion 623 of the third layer 63 may press down on the membrane of the bearing device. However, since the unformed portion in the second height section shown in FIG. 6G is only a small part of the second height section, this risk is tolerable to those skilled in the art.

[0120] Figures 6H-6I illustrate the end compensation layer for the second height segment of the target object. The end compensation layer, or fourth layer 64, is adhered to the third layer 63. Similar to the third layer 63, the end compensation layer, or fourth layer 64, has two regions of different thicknesses. Specifically, the fourth layer 64 comprises a second portion 644 made of material B and a first portion 664 made of material C, the first portion 664 being thicker than the second portion 644.

[0121] Although Figures 6H-6I show the formation of the second portion 644 of the fourth layer 64 first, followed by the formation of the first portion 664 of the fourth layer 64, in other embodiments, the first portion 664 of the fourth layer 64 may be formed first, followed by the formation of the second portion 644 of the fourth layer 64.

[0122] Figures 6A-6I illustrate the steps for manufacturing the second height segment of the target object. Those skilled in the art will understand that, depending on the total thickness of the second height segment of the target object, the target object may have multiple second or third layers. For example, after forming the first layer (or “initial compensation layer”), 100 layers (or “intermediate layers”) are formed consecutively in a manner that forms the second or third layer, and finally, the end compensation layer of the second height segment is formed in a manner that forms the fourth layer.

[0123] The embodiments shown in Figures 6A-6I demonstrate the manufacture of objects having different portions composed of different materials within the same layer. It is understood that the multiple intermediate layers of the second height segment Z2 may have the same or different thicknesses. For example, each portion 662, 642, 622 of the second layer (i.e., the first of the multiple intermediate layers) 62 has a thickness of 50 μm, and each portion 663, 643, 623 of the third layer (i.e., the second of the multiple intermediate layers) 63 has a thickness of either 70 μm or 50 μm.

[0124] The formation of each portion of each layer in the second height segment of the target object is associated with the corresponding slicing parameters. The slicing of the target object may include an initial slicing layer, multiple intermediate slicing layers, and an end slicing layer. For example, a 3D object data model has 500 slice layers, each slice layer being 50 μm thick. An alternating curing strategy can be used from layer 100 to layer 300. For instance, first, a 50 μm thick material C is cured to form the first part of the first layer of the second height segment; then, a 100 μm thick material B (i.e., twice the slice layer thickness) is cured to form the second part of the first layer of the second height segment; next, a 150 μm thick material A (i.e., three times the slice layer thickness) is cured to form the third part of the first layer of the second height segment; then, a 150 μm thick material C (i.e., three times the slice layer thickness) is cured to form the first part of the second layer of the second height segment; then, a 150 μm thick material B is cured to form the second part of the second layer of the second height segment; then, a 150 μm thick material A is cured to form the third part of the second layer of the second height segment; ...; the steps shown in Figures 6A-6I are executed continuously until the end compensation layer of the second height segment is formed.

[0125] The initial slice layer of the target object can be used to form the initial compensation layer of the second height segment, the intermediate slice layer of the target object can be used to form the intermediate layer of the second height segment, and the final slice layer of the target object can be used to form the final compensation layer of the second height segment. The thickness of the slice of the target object (or a portion thereof) can be designed, for example, 2μm to 200μm, 5μm to 150μm, 10μm to 100μm, 20μm to 80μm, 25μm to 75μm, 30μm to 60μm, 40μm, or 50μm.

[0126] Those skilled in the art will understand that the drive device used to drive the forming platform to move vertically has two parameters: positioning accuracy and repeatability, with repeatability being higher than positioning accuracy. Positioning accuracy is the error between a specified movement and the actual movement, while repeatability is the error in each reciprocating motion under ideal positioning accuracy. For example, a ball screw has a positioning accuracy of 25 μm / 300 mm and a repeatability of 2 μm / 300 mm. Therefore, the solutions shown in Figures 6A-6I reduce or avoid the risks caused by positioning accuracy while still achieving high printing accuracy, at least due to repeatability.

[0127] Figure 7 illustrates an embodiment for forming an object comprising two materials. As shown in Figure 7, the object 700 comprises multiple layers. Material A is exposed and cured to form a first portion 711 of a first layer 71 of the object 700, which contains only material A. Material B is exposed and cured to form a second portion 712 of the first layer 71 of the object 700, which contains only material B and is formed on the first portion 711. Material A is exposed and cured to form a first portion 721 of a second layer 72 of the object 700, which contains only material A. Material B is exposed and cured to form a second portion 722 of the second layer 72 of the object 700, which contains only material B and is formed on the first portion 721. Material A is exposed and cured to form a first portion 731 of a third layer 73 of the object 700, which contains only material A. Material B is exposed and cured to form a second portion 732 of the third layer 73 of the object 700, which contains only material B and is formed on the first portion 731. Exposure and curing material A is used to form a fourth layer 741 of object 700, which consists of only a single material A.

[0128] It is understood that there is a horizontal difference between two adjacent target layers composed of different materials (here, "different materials" refers to materials from different material regions, not necessarily materials with different physical and / or chemical properties). The term "horizontal difference" can be interpreted as the height difference between the lower surfaces of the two adjacent target layers, or the height difference between the upper surfaces of the two adjacent target layers, or the height difference between the virtual mid-surfaces of the two adjacent target layers, or similarly.

[0129] In this document, unless otherwise specified, the terms "first material" and "second material" refer to different types of materials. It is understood that the terms "first material" or "second material" can refer to a material having a single component or a mixture of multiple components.

[0130] The terms "tray" or "carrying device" as used herein can be configured in a variety of ways. In some embodiments, the tray includes multiple boxes in which liquid or paste-like material is contained. In some embodiments, the tray includes multiple plate-like elements on which liquid or paste-like material is applied. In some embodiments, the tray includes at least one box and at least one plate-like element. The forming platform is sized to allow it to fall into the printing area of ​​the respective tray (e.g., box or plate-like element).

[0131] The terms “forming platform” and “tray” used herein should be understood as horizontal. In the event that a forming platform or tray is not horizontal due to manufacturing or layout errors, it also falls within the scope of protection of this application.

[0132] In some embodiments, the molding platform is moved to a cleaning area to clean the three-dimensional object being molded on the platform before moving it from a support for the first material to a support for the second material. This cleaning step helps prevent mixing between the first and second materials.

[0133] In some embodiments, cleaning is performed after at least two first portions or at least two second portions have been formed. The frequency of cleaning can be controlled, for example, cleaning is performed after five slice layers have been cured.

[0134] In some embodiments, cleaning includes at least one of the following: a rotational forming platform, wiping the three-dimensional object, applying airflow to the three-dimensional object, and surrounding the three-dimensional object with an absorbent to remove excess printing material. For example, a rotational forming platform can be used to remove material adhering to the cured portion. Alternatively, an absorbent, such as a sponge or lint-free cloth, can be used to absorb material from the cured portion. These cleaning methods can be used individually or in any combination of methods in any order. For example, material adhering to the cured portion can be removed first by a rotational forming platform, followed by the absorption of a sponge to absorb any remaining material. Another example is applying airflow (e.g., a nozzle) to the three-dimensional object to blow away or absorb material adhering to the cured portion, followed by the absorption of a non-woven cloth to absorb any remaining material.

[0135] In some embodiments, excess material in the first material region is cleaned during or after moving the molding platform from the first material region to the second material region. Alternatively or additionally, excess material in the second material region is cleaned during or after moving the molding platform from the second material region to the first material region.

[0136] In some embodiments, a scraper is used to clean excess material in the first material area.

[0137] In some embodiments, the first material in the first material region is different from the second material in the second material region. The properties of the first material and the second material may differ; for example, the first material may have a higher viscosity, while the second material may have a lower viscosity.

[0138] In some embodiments, the color of the first material is different from the color of the second material. This allows materials of different colors to be cured in the same slice layer or multiple adjacent slice layers.

[0139] In some embodiments, the first material is a mixture or composite material. Alternatively, it may comprise multiple materials or a mixture of multiple materials. For example, a printing material composed of at least one of cyan, magenta, yellow, and black (CMYK). For example, the first material may include cyan and yellow materials. For example, the first material may include a mixture of cyan and yellow materials.

[0140] In some embodiments, the first material is an additive. For example, the additive includes at least one of the following: pigment, dye, defoamer, leveling agent, wetting agent, dispersant, matting agent.

[0141] In some embodiments, the first material and / or the second material are liquid photocurable materials arranged in a tray of a 3D printing device.

[0142] In some embodiments, the first material and / or the second material are applied to the material region via a nozzle. For example, materials within a predetermined viscosity range are applied via the nozzle. The predetermined viscosity threshold corresponding to the available viscosity printing materials at room temperature (e.g., 10–40°C, preferably 20–30°C, e.g., 25°C) is between 50 centipoise and 500,000 centipoise, preferably between 500 centipoise and 200,000 centipoise, more preferably between 100 and 500 centipoise, and particularly preferably between 200 and 300 centipoise.

[0143] When performing photopolymer printing based on a pattern (e.g., using DLP or LCD printing equipment), the printed layer thickness is, for example, 5 μm to 200 μm, and the material container of the 3D printing equipment can hold photosensitive resin with a height or depth of 500 μm to 2000 μm. When the object to be printed is composed of at least two materials, the forming platform of the 3D printing equipment needs to switch between at least two containers. It is understood that when the forming platform (on which a portion of the cured object is adhered) switches from a first container containing material A to a second container containing material B, some material A will adhere to the surface (bottom and side surfaces) of the object leaving the first container. If the forming platform is directly immersed in material B in the second container, there is a greater risk that the material A adhering to the object's surface will mix with material B. Similarly, when the molding platform (on which a partially cured object is adhered) switches from a second container containing material B to a first container containing material A, some material B will adhere to the surface (bottom and side surfaces) of the object leaving the first container. If the molding platform is directly immersed in material A in the first container, there is a greater risk that the material B adhering to the object's surface will mix with the material A in the first container. If multiple switches are required between the first and second containers, the risk of material A mixing with material B in either the first or second container is even greater.

[0144] In some embodiments, after the forming platform (on which a portion of the solidified object is adhered) leaves the first container containing material A, the object adhering to the forming platform can be cleaned, and then the forming platform, carrying the cleaned object, can be immersed in a second container containing material B. It is understood that the bottom and side surfaces of the object adhering to the forming platform need to be cleaned. The area of ​​the bottom surface to be cleaned depends on the size of the object to be printed, and the area of ​​the side surfaces to be cleaned depends on the size of the contact area between the object adhering to the forming platform and the container. When the liquid level in the container is high, the area of ​​the side surface of the object adhering to the forming platform in contact with the material is large, resulting in a large area of ​​the side surface to be cleaned, which increases the difficulty of cleaning. For example, when the slice layer thickness is 50 μm, a liquid level of 1000 μm to 2000 μm (the liquid level at the bottom of the container is 0, and the liquid level at the surface of the first container is 1000 μm to 2000 μm) is advantageous for performing multiple prints and then replenishing material A, but the side surface of the object adhering to the forming platform has material A adhering to it at a liquid level of 995 μm to 1995 μm. If the liquid level in the first container is adjusted to 50μm to 1000μm, the area to be cleaned will shrink. To meet the requirement of constructing objects in layers, the liquid level in the first container must be greater than or equal to the thickness of the current layer to be cured. For example, if the thickness of the current layer to be cured is 100μm, then the liquid level in the first container must be at least 100μm.

[0145] Considering the potential error in the molding platform along the Z-axis (or the construction direction of the object, or the stacking direction of the slice layers), the liquid level in the first container should be greater than the sum of the current layer thickness to be cured and the allowable error. For example, if the allowable error is 20 μm, then the liquid level in the first container should be at least 120 μm.

[0146] It is understandable that the thickness of the current layer to be cured may not be equal to the slice layer thickness. For example, when the slice layer thickness is 50 μm, the thickness of the current layer to be cured could be, for example, 50 μm, 100 μm, 120 μm, or 150 μm. The thickness of the current layer to be cured can be determined based on the pattern of the slice image according to different curing depths.

[0147] Figure 8 shows a schematic diagram of a portion of the additive manufacturing system. For simplicity, optical units and some support devices are omitted. The target object 800 comprises three parts 820, 840, and 860; this view is a cross-sectional view of the target object 800. The first part 820 of the target object 800 is made of a first type of material A, the second part 840 is made of a second type of material B, and the third part 860 is made of a third type of material C. A portion 840 of the cured target object 800, made of material B, is adhered to the molding platform 881 of the additive manufacturing system. The additive manufacturing system drives at least one of the molding platform 881 or the support device 883 via a drive mechanism (not shown) to align the molding platform 881 with the support device 883, thereby allowing the material carried by the support device 883 to be cured and adhered to the molding platform 881. The bottom and side surfaces of the target object 800 adhered to the molding platform 881 need to be cleaned. The side surfaces of the target object 800 include outer wall side surfaces 8220 and 8660 and inner wall side surfaces 8221 and 8661. As can be seen from the cross-sectional view of the target object 800, the inner wall side surfaces define holes. During printing, the surface portions associated with these holes carry resin. For example, when using centrifugation to remove the resin, cleaning these hole portions is more difficult than cleaning the outer wall side surfaces 8220 and 8660. In this case, adjusting the liquid level in the carrier device 883 to a certain height helps reduce the area of ​​material adhering to the inner wall side surfaces of the holes, making the inner wall side surfaces easier to clean.

[0148] The inventors also discovered that when the liquid level of the material in the container is high, the probability of air bubbles appearing in the cured layer at the bottom of the container is low; conversely, when the liquid level of the material in the container is low, the probability of air bubbles appearing in the cured layer at the bottom of the container is high. The liquid level of the material in the container directly affects the immersion travel of the molding platform (and the object adhered to it), and thus affects the number of air bubbles in the cured layer. Despite other factors related to air bubbles, the inventors found that, all other things being equal, a higher liquid level is beneficial in suppressing the number and / or size of air bubbles in the cured layer.

[0149] The following are some printing test results.

[0150] Example 1: The liquid level is set to 1000 μm, and the thickness of the layer to be cured is 100 μm. After curing the 100 μm thick layer, the cured object on the molding platform is cleaned by bringing the cured object into contact with a cleaning mechanism (including cloth or sponge) to remove the printing material from the surface of the cured object. The cleaning effect is found to be poor (the sides are difficult to clean). After switching between a container containing white material A and a container containing red material B 20 times, abnormal portions caused by the mixing of materials A and B (i.e., the cured object includes completely red portions, completely white portions, and mixed portions) are formed in the cured object, and multiple identifiable bubbles (e.g., number S) are formed. Mixed portions appear in both containers (i.e., white material A is contaminated by red material B, and red material B is contaminated by white material A).

[0151] Example 2: The liquid level is set to 400 μm, and the thickness of the layer to be cured is 100 μm. After curing the 100 μm thick layer, the cured object on the molding platform is cleaned by bringing the cured object into contact with a cleaning mechanism (including cloth or sponge) to remove the printing material from the surface of the cured object. The cleaning effect was found to be poor (the sides were difficult to clean). After switching between a container containing white material A and a container containing red material B 20 times, no abnormal parts were formed in the cured object (i.e., the cured object did not contain mixed colors), but several identifiable bubbles (e.g., number S) were formed, as shown in Figure 9A. No mixed colors appeared in either container (i.e., white material A was not contaminated by red material B, and red material B was not contaminated by white material A).

[0152] Example 3: The liquid level is set to 200 μm, and the thickness of the layer to be cured is 100 μm. After curing the 100 μm thick layer, the cured object on the molding platform is cleaned by bringing the cured object into contact with a cleaning mechanism (including cloth or sponge) to remove the printing material from the surface of the cured object. The cleaning effect was found to be good (sides were easy to clean). After switching between a container containing white material A and a container containing red material B 20 times, no abnormal parts were formed in the cured object (i.e., the cured object included completely red and completely white parts), but several identifiable bubbles were formed (the number was, for example, S*130%), as shown in Figure 9B. There were no mixed color parts in either container (i.e., white material A was not contaminated by red material B, and red material B was not contaminated by white material A).

[0153] Different materials are used to form different objects in different scenarios, thus requiring different levels of control over, for example, the presence of air bubbles. For instance, with transparent or translucent materials (e.g., pink materials used to create gingival models or white materials used to create dental crown models), air bubbles in the cured object are more easily visible to the human eye, making it particularly important to control the number of air bubbles in the cured object. Therefore, the liquid level for transparent or translucent materials is typically 200 μm to 500 μm, such as 400 μm, to obtain an object with a certain air bubble distribution density. Conversely, with opaque materials, air bubbles in the cured object may be located inside the object and are therefore less easily visible to the human eye, resulting in less stringent requirements or restrictions on air bubbles. Therefore, the liquid level for opaque materials is typically 50 μm to 300 μm, such as 100 μm, to facilitate related cleaning operations.

[0154] Those skilled in the art will understand that the probability of air bubbles appearing in certain types of printing materials is low, and in such cases, the design of the liquid level can disregard the risk of air bubbles. In some embodiments, defoamers or similar agents may be applied to the printing material to reduce the risk of a large number of air bubbles.

[0155] Too low a liquid level will produce bubbles and it is difficult to control the precision, while too high a liquid level will increase the difficulty of cleaning.

[0156] To avoid color mixing of materials in multiple containers, the liquid level of the material in each container should be 20μm to 1000μm, for example, 40μm to 950μm, for example, 50μm to 800μm, for example, 60μm to 700μm, for example, 70μm to 600μm, for example, 80μm to 500μm, for example, 90μm to 480μm, for example, 40μm, for example, 80μm, for example, 90μm, for example, 100μm, for example, 110μm, for example, 120μm, for example, 150μm, for example, 200μm, for example, 250μm, for example, 300μm, for example, 320μm, for example, 350μm, for example, 380μm, for example, 400μm, for example, 450μm.

[0157] For at least the construction of a single layer (or a single part) of the target object, the liquid level of the material in each container should be greater than the thickness of the layer to be cured. Considering that the thickness of the slice layer or the layer to be cured is 20 μm to 200 μm, the liquid level of the material in each container should be, for example, 20 μm to 1000 μm, 30 μm to 800 μm, 40 μm to 700 μm, 50 μm to 600 μm, 60 μm to 500 μm, 70 μm to 480 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 150 μm, 200 μm, 250 μm, 300 μm, 320 μm, 350 μm, 380 μm, 400 μm, or 450 μm. Taking a layer thickness of 50μm as an example, the liquid level can be 50μm to 1000μm, 60μm to 950μm, 75μm to 700μm, 100μm to 600μm, 200μm to 500μm, or 300μm to 400μm. The liquid level can be 1 to 20 times the thickness of the layer to be cured, for example, 1.5 to 18 times, 2 to 8 times, 3 to 7 times, 4 to 6 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, 3.0 times, 3.1 times, etc. 3.2 times, for example 3.3 times, for example 3.4 times, for example 3.5 times, for example 3.6 times, for example 3.7 times, for example 3.8 times, for example 3.9 times, for example 4.0 times, for example 4.1 times, for example 4.2 times, for example 4.3 times, for example 4.4 times, for example 4.5 times, for example 4.6 times, for example 4.7 times, for example 4.8 times, for example 4.9 times, for example 5.0 times, for example 5.1 times, for example 5.2 times, for example 5.3 times, for example 5.4 times, for example 5.5 times, for example 5.6 times, for example 5.7 times, for example 5.8 times, for example 5.9 times.

[0158] To at least reduce the number of bubbles, the liquid level of the material in each container should be 100μm to 2000μm, for example 120μm to 1000μm, for example 150μm to 900μm, for example 160μm to 800μm, for example 180μm to 700μm, for example 190μm to 600μm, for example 200μm, for example 250μm, for example 300μm, for example 350μm, for example 400μm, for example 450μm, for example 500μm, for example 550μm.

[0159] This application provides a three-dimensional printing method for manufacturing a target object. The three-dimensional printing method includes: providing a first material container having a first printing area, irradiating the first printing area to solidify a first material and form a first portion of a first layer, the first portion of the first layer having a first thickness; providing a second material container having a second printing area, irradiating the second printing area to solidify a second material and form a second portion of the first layer, the second portion of the first layer having a second thickness, wherein, during irradiation, the liquid level of the first material container and the second material container is maintained at 40 μm to 950 μm, and is more than 1.2 times the second thickness.

[0160] In some embodiments, the liquid level in the first and second material containers is 1.5 to 20 times the second thickness, preferably 2 to 8 times, more preferably 3 to 7 times, and even more preferably 4 to 6 times. For example, 1.8 to 8 times, 2 to 6 times, or 3 to 5 times.

[0161] In some embodiments, the liquid level in the first material container and the second material container is 100μm to 800μm, for example 120μm to 700μm, preferably 150μm to 600μm, preferably 180μm to 500μm, and preferably 200μm to 400μm.

[0162] Taking into account at least the number of bubbles and color mixing, the liquid level in each material container is 150μm to 600μm, preferably 180μm to 500μm, and more preferably 200μm to 400μm.

[0163] Figure 10 shows a schematic diagram of a printed part comprising two printing materials. The 3D printing equipment or additive manufacturing system 1000 includes a forming platform 1010 on which the printed part is adhered. A first layer 1031 of the printed part is adhered to the forming platform 1010, a second layer 1032 of the printed part is adhered to the first layer 1031, and a third layer 1033 of the printed part is adhered to the second layer 1032. Layers 1031, 1032, and 1033 of the printed part are entirely composed of material A.

[0164] A fourth layer of the printed material is adhered to the third layer 1033. The fourth layer comprises a first portion 10341 made of material A and a second portion 10342 made of material B, which is different from material A. The first portion 10341 and the second portion 10342 are spaced apart from each other. The first portion 10341 and the second portion 10342 have the same thickness, for example, 80 μm.

[0165] A fifth layer of the printed material is adhered to the fourth layer. The fifth layer comprises a first portion 10351 made of material A and a second portion 10352 made of material B. The first portion 10351 of the fifth layer is adhered to the first portion 10341 of the fourth layer, and the second portion 10352 of the fifth layer is adhered to the second portion 10342 of the fourth layer. The first portion 10351 and the second portion 10352 have the same thickness, for example, 100 μm.

[0166] A sixth layer of the printed material is adhered to the fifth layer. The sixth layer comprises a first portion 10361 made of material A and a second portion 10362 made of material B. The first portion 10361 of the sixth layer is adhered to the first portion 10351 of the fifth layer, and the second portion 10362 of the sixth layer is adhered to the second portion 10352 of the fifth layer. The first portion 10361 and the second portion 10362 have the same thickness, for example, 90 μm.

[0167] In the embodiment shown in Figure 10, a first layer 1031, a second layer 1032, and a third layer 1033 are formed first, followed by a fourth, fifth, and sixth layer. The first portion 10341 of the fourth layer is formed first, followed by the second portion 10342. The first portion 10351 of the fifth layer is formed first, followed by the second portion 10352. The second portion 10362 of the sixth layer is formed first, followed by the first portion 10361. In some variations, the order in which the first and second portions are formed in any of the fourth, fifth, or sixth layers is arbitrary.

[0168] Figure 11 shows a schematic diagram of a printed part comprising two printing materials. The 3D printing equipment or additive manufacturing system 1100 includes a forming platform 1110 on which the printed part is adhered. A first layer 1131 of the printed part is adhered to the forming platform 1110, a second layer 1132 of the printed part is adhered to the first layer 1131, and a third layer 1133 of the printed part is adhered to the second layer 1132. Layers 1131, 1132, and 1133 of the printed part are entirely composed of material A.

[0169] A fourth layer of the printed material is adhered to the third layer 1133. The fourth layer comprises a first portion 11341 made of material A and a second portion 11342 made of material B, which is different from material A. The first portion 11341 and the second portion 11342 are spaced apart from each other. The first portion 11341 and the second portion 11342 have different thicknesses. For example, the thickness of the first portion 11341 is 50 μm, and the thickness of the second portion 11342 is 100 μm.

[0170] A fifth layer of the printed material is adhered to the fourth layer. The fifth layer comprises a first portion 11351 made of material A and a second portion 11352 made of material B. The first portion 11351 of the fifth layer is adhered to the first portion 11341 of the fourth layer, and the second portion 11352 of the fifth layer is adhered to the second portion 11342 of the fourth layer. The first portion 11351 and the second portion 11352 have different thicknesses. For example, the thickness of the first portion 11351 is 100 μm, and the thickness of the second portion 11352 is 50 μm.

[0171] In the embodiment shown in Figure 11, a first layer 1131, a second layer 1132, and a third layer 1133 are first formed, followed by a fourth and a fifth layer. A first portion 11341 of the fourth layer is first formed, followed by a second portion 11342. A first portion 11351 of the fifth layer is first formed, followed by a second portion 11352.

[0172] Figure 12 illustrates the carrier device of an additive manufacturing system. The additive manufacturing system 1200 includes a forming platform 1210, an optical unit 1260, and carrier devices 1280 and 1290. Carrier device 1280 carries material A, and carrier device 1290 carries material B, which is different from material A. Therefore, the additive manufacturing system 1200 can form an object comprising material A and / or material B. For example, carrier device 1280 moves to align with the forming platform 1210 and optical unit 1260, and then optical unit 1260 projects light (e.g., UV light) through at least a partially transparent bottom of carrier device 1280, causing the material A carried by carrier device 1280 to solidify. The solidified material A adheres to the forming platform 1210 and forms a portion 1231 of the object. Then, the carrier 1290 is moved to align with the molding platform 1210 and the optical unit 1260, and then the optical unit 1260 projects light so that the light passes through at least the partially transparent bottom of the carrier 1290 and solidifies the material B carried by the carrier 1290. The solidified material B adheres to the molding platform 1210 and forms part 1232 of the object.

[0173] In some variations, the support devices 1280 and 1290 are immovable or stationary, while the forming platform 1210 is movable. For example, the forming platform 1210 may be moved to align itself with either the support device 1280 or the support device 1290. In some variations, light projected by a single optical unit 1260 can simultaneously radiate to both the support device 1280 and the support device 1290. In some variations, each support device is assigned one or more optical units 1260. It is understood that the support devices, optical units, and forming platform are configured to accommodate the formation of two (or more) materials.

[0174] The type of support device can be designed. For example, an additive manufacturing system includes a support device for supporting material A, a support device for supporting material B, a support device for supporting material C, and a support device for supporting material D. The number of support devices can be designed. For example, an additive manufacturing system includes a support device for a single material A, two support devices for supporting material B, two support devices for supporting material C, and three support devices for supporting material D.

[0175] Figure 13 illustrates the cleaning unit of the additive manufacturing system. The additive manufacturing system 1300 includes a molding platform 1310, an optical unit 1360, and carrier devices 1380 and 1390. The carrier devices 1380 and 1390 are located between the molding platform 1310 and the optical unit 1360. The molding platform 1310 is movable along the Z-axis or in the stacking direction of multiple layers. For example, the molding platform 1310 moves along the Z-axis such that the distance between the molding platform 1310 and at least a partially transparent film of the carrier device 1380 is 60 μm. Then, the optical unit 1360 projects light onto the liquid or paste material A contained in the carrier device 1380 according to a predetermined pattern, causing the material A between the molding platform 1310 and the film of the carrier device 1380 to solidify and form a first portion 1331. The cross-sectional profile of the first portion 1331 conforms to the predetermined pattern, such as a rectangular, circular, or curved closed profile.

[0176] After forming layer 1331, the forming platform 1310 carrying the first portion 1331 leaves the carrier device 1380. It is understood that the first portion 1331 leaving the carrier device 1380 has uncured liquid or paste material A attached to it. If the first portion 1331 leaving the carrier device 1380 directly enters the liquid or paste material B carried by the carrier device 1390, there is a risk that the attached material A will contaminate material B (due to the mixing of material A and material B). To at least mitigate this risk, the additive manufacturing system 1300 also includes a cleaning unit 1370, which is used at least to remove uncured material attached to the cured object (e.g., the first portion 1331).

[0177] The cleaning unit 1370 includes, for example, an airflow assembly. In some embodiments, the airflow assembly applies a positive pressure airflow to the cured object to blow off uncured material adhering to the cured object. In some embodiments, the airflow assembly applies a negative pressure airflow to the cured object to adsorb uncured material adhering to the cured object.

[0178] The cleaning unit 1370 includes, for example, a wiping assembly. In some embodiments, the wiping assembly includes, for example, a brush or cloth that wipes away uncured material adhering to a cured object. For example, the molding platform 1310 remains stationary, and the brush or cloth moves to wipe away uncured material on a first portion 1331 carried by the molding platform 1310.

[0179] The cleaning unit 1370 includes, for example, an adsorption component. In some embodiments, the adsorption component includes, for example, a sponge or cloth that adsorbs uncured material adhering to a cured object. For example, the cleaning unit 1370 remains stationary while a first portion 1331 carried by the molding platform 1310 moves to contact the sponge or cloth, causing uncured material on the first portion 1331 to penetrate the sponge or cloth.

[0180] The cleaning unit 1370 includes, for example, a cleaning container containing a cleaning agent. In some embodiments, the cleaning agent is water, alcohol, or isopropanol, and the first portion 1331 carried by the molding platform 1310 is immersed in the cleaning agent in the cleaning container. In some embodiments, the cleaning agent is a resin material to be cured. For example, the first portion 1331 carried by the molding platform 1310 is composed of resin material A, and resin material B is to be cured next. In this case, the first portion 1331 is first moved and immersed in the resin material B contained in the cleaning container, so that the resin material A attached to the first portion 1331 mixes with the resin material B in the cleaning container. Then, the first portion 1331 leaves the cleaning container and moves to the carrier device 1390 to prepare for the formation of a new portion.

[0181] The cleaning unit 1370 includes, for example, a spraying assembly. The spraying assembly sprays a liquid to wash away uncured material adhering to a cured object. For example, the spraying assembly sprays water, alcohol, or isopropyl alcohol.

[0182] The cleaning unit 1370 includes, for example, a heating component. The heating component is used to transfer heat to uncured material attached to a cured object. The viscosity of the uncured material changes with temperature, and when the temperature of the uncured material rises to a predetermined value or range, the uncured material easily detaches from the cured object. In some embodiments, the heating component includes a heat-generating component (e.g., a PTC heater) and a heat-conducting component (e.g., a cloth).

[0183] In some embodiments, the cleaning unit 1370 includes at least one of an airflow assembly, a wiping assembly, an adsorption assembly, a cleaning container, a spraying assembly, or a heating assembly.

[0184] The molding platform 1310 is rotatable so that the uncured material adhering to the cured object is thrown off. The molding platform 1310 rotates so that the resin on the first part 1331 it carries is thrown off.

[0185] After being cleaned by the cleaning unit 1370, the molding platform 1310 carrying the first part 1331 moves and contacts the material B in the support device 1390, and solidifies the material B to form the second part 1332. Similarly, the molding platform 1310, having left the support device 1390, moves to a cleaning position for cleaning by the cleaning unit 1370. Then, the molding platform 1310 carrying the first part 1331 and the second part 1332 moves and contacts the material A in the support device 1380, and solidifies the material A to form the third part 1333.

[0186] Understandably, the cleaning frequency is settable. In some embodiments, before the molding platform 1310 leaves the support device 1380 and approaches the support device 1390, the molding platform 1310 moves to a cleaning position to allow the cleaning unit 1370 to clean the uncured material; before the molding platform 1310 leaves the support device 1390 and approaches the support device 1380, the molding platform 1310 moves to a cleaning position to allow the cleaning unit 1370 to clean the uncured material. In some embodiments, the molding platform 1310 leaves the support device 1380 and approaches the support device 1390 to form a second portion 1332, then the molding platform 1310 leaves the support device 1390 and approaches the support device 1380 to form a third portion 1333, and then, before the molding platform 1310 leaves the support device 1380 and approaches the support device 1390, the molding platform 1310 moves to a cleaning position to allow the cleaning unit 1370 to clean the uncured material.

[0187] Understandably, it is necessary to clean the bottom and side surfaces of objects adhering to the forming platform (e.g., the first part 1331, the second part 1332, and the third part 1333). The area of ​​the bottom surface to be cleaned depends on the size of the object to be printed, and the area of ​​the side surface to be cleaned depends on the size of the contact area between the object adhering to the forming platform and the container. When the liquid level in the container is high, the contact area between the side surface of the object adhering to the forming platform and the material is large, resulting in a larger area of ​​the side surface to be cleaned, which increases the difficulty of cleaning. For example, when the slice layer thickness is 50 μm, a liquid level of 1000 μm to 2000 μm (the liquid level at the bottom of container 1380 is 0, and the liquid level at the surface of container 1380 is 1000 μm to 2000 μm) is beneficial for performing multiple prints and then replenishing material A, but material A is attached to the side surface of the object adhering to the forming platform at a liquid level of 995 μm to 1995 μm. If the liquid level in container 1380 is adjusted to 50μm to 1000μm, the area to be cleaned will shrink. To meet the requirement of constructing objects in layers, the liquid level in the container must be greater than or equal to the thickness of the current layer to be cured. For example, if the thickness of the current layer to be cured is 100μm, then the liquid level in the first container must be at least 100μm.

[0188] Figure 14 shows a schematic diagram of a portion of an additive manufacturing system. For simplicity, optical units and some support devices are omitted. The additive manufacturing system includes a forming platform 1410 on which multiple support elements 1420 are adhered, and a target object is formed on the support elements 1420. The target object comprises three parts 1430, 1440, and 1450. The first part 1430 is made of a first type of material A, the second part 1440 is made of a first type of material A, and the third part 1450 is made of a second type of material B. The first part 1430 is adhered to the multiple support elements 1420, and the second part 1440 and the third part 1450 are formed on the first part 1430. A support device 1460 of the additive manufacturing system contains the first type of material A. The second part 1440 and the third part 1450 shown in Figure 14 are partially immersed in the material contained in the support device 1460 to prepare for curing of material A to a predetermined thickness.

[0189] In the embodiment shown in Figure 14, the bottom surface and a portion of the side surfaces of the target object contact material A, which subsequently needs to be cleaned. For material A to cure and form a new cured layer, the entire bottom surface of the target object in Figure 14 (i.e., the bottom surfaces of the second portion 1440 and the third portion 1450) must be in contact with material A, while only a portion of the side surfaces of the target object are in contact with material A. The area of ​​the side surfaces of the target object in contact with material A is related to the liquid level in the support device 1460. An increased liquid level leads to an expansion of the area of ​​the side surfaces of the target object in contact with material A, which increases the difficulty of cleaning the target object in many scenarios. For example, the aforementioned expanded area requires the cleaning unit to have a larger working range. Alternatively or additionally, the aforementioned expanded area means that more material adheres to the side surfaces of the target object, thus increasing the amount of material to be removed or separated.

[0190] The second portion 1440 and the third portion 1450 shown in Figure 14 are partially immersed in the material A contained in the carrier 1460. The second portion 1440 has a first side portion 14410 (e.g., having a flat surface) that is away from the third portion 1450 and in contact with the material A, and a second side portion 14420 (e.g., having a flat surface) that is close to the third portion 1450 and in contact with the material A. The third portion 1450 has a first side portion 14510 (e.g., having a flat surface) that is close to the second portion 1440 and in contact with the material A, and a second side portion 14520 (e.g., having a flat surface) that is away from the second portion 1440 and in contact with the material A. The second side 14420 of the second portion 1440 and the first side 14510 of the third portion 1450 define a slit, the width of which is the distance between the second side 14420 of the second portion 1440 and the first side 14510 of the third portion 1450, for example, 100 μm, 300 μm, or 500 μm. It is understood that the width and depth (or “height”) of the slit affect the removal of material adhering to the sides 14410, 14420, 14510, and 14520; however, the width of the slit is constant (constrained by the dimensions of the target object itself), and the depth or height of the slit depends at least on the liquid level of the material carried by the carrier device.

[0191] In some examples, when using centrifugal rotation to remove material adhering to the sides, the material adhering to sides 14420 and 14510 is not easily removed due to the small width of the slit (e.g., within 2 mm), especially when the depth or height of the slit is large. Lowering the liquid level of the material carried by the carrier device helps to reduce or decrease the depth or height of the slit, thereby facilitating the removal of material adhering to the sides. It is understood that the aforementioned cleaning unit (which can be of various forms) can be used to clean the material on the sides defining the slit, and a lower liquid level facilitates the cleaning process. The liquid level is, for example, 100 μm to 1000 μm.

[0192] In some embodiments, the slit shown in FIG14 is replaced by a hole with a diameter of, for example, 100 μm to 5000 μm.

[0193] The inventors also discovered that when the liquid level of the material carried by the support device (e.g., a container) is high, the probability of air bubbles appearing in the layer cured at the bottom of the container is low; however, when the liquid level of the material in the container is low, the probability of air bubbles appearing in the layer cured at the bottom of the container is high. The liquid level of the material in the container directly affects the immersion travel of the molding platform (and the object adhered to it), and thus affects the number of air bubbles in the layer to be cured. Despite other factors related to air bubbles, the inventors found that, all other things being equal, a higher liquid level is beneficial in suppressing the number and / or size of air bubbles in the layer to be cured. Figures 9A-9B provide schematic diagrams of products with different numbers of pores / depressions (due to air bubbles).

[0194] Figure 15 shows a schematic diagram of a portion of an additive manufacturing system. The additive manufacturing system 1500 includes a molding platform 1510, a first container 1580, and a second container 1590. Both the first container 1580 and the second container 1590 are box-shaped. The first container 1580 contains material A, and the second container 1590 contains material B, which is different from material A. To ensure that the liquid level of the material in the containers is maintained at a predetermined value or a predetermined range (e.g., 100 μm to 2000 μm, 100 μm to 8000 μm), a material supply unit is provided. The material supply unit 1530 supplies material A to the first container 1580, for example, through a channel or pipe 1540. In some embodiments, the channel or pipe 1540 is omitted. The material supply unit 1550 supplies material B to the second container 1590, for example, through a channel or pipe 1560. In some embodiments, the channel or pipe 1560 is omitted. In some embodiments, the first container 1580 and the second container 1590 are each equipped with a sensor for detecting the liquid level.

[0195] Figure 16 shows a schematic diagram of a portion of an additive manufacturing system. The additive manufacturing system 1600 includes a forming platform, a first container 1680, and a second container 1690. Both the first container 1680 and the second container 1690 are box-shaped. The first container 1680 contains material A, and the second container 1690 contains material B, which is different from material A. A material supply unit 1630 supplies material A to the first container 1680, and a leveling unit 1610 is movable on a horizontal plane to make the liquid level in the first container 1680 uniform. A material supply unit 1650 supplies material B to the second container 1690, and a leveling unit 1620 is movable on a horizontal plane to make the liquid level in the second container 1690 uniform.

[0196] Leveling unit 1610 and leveling unit 1620 move on the same or different horizontal planes. For example, leveling unit 1610 moves such that the liquid level of the material in the first container 1680 is maintained at approximately 1800 μm, while leveling unit 1620 moves such that the liquid level of the material in the second container 1690 is maintained at approximately 1800 μm or 2200 μm. The term "horizontal plane" here refers to a plane perpendicular to the Z-axis direction. The movement of leveling unit 1610 and leveling unit 1620 includes any of the following: translation, rotation, or pivoting. For example, the arrows in Figure 16 indicate the direction of translation.

[0197] In the embodiment shown in Figure 16, leveling unit 1610 is used to ensure a uniform liquid surface 1682, the liquid level of which is, for example, 2000 μm. Leveling unit 1620 is used to ensure a uniform liquid surface 1692, the liquid level of which is, for example, 500 μm.

[0198] Figure 17 illustrates an embodiment of maintaining a printing liquid level. As shown in Figure 17, a material supply device 1720 supplies material to a container 1750 at a supply position designed close to the sidewall of the container 1750. Continuous or intermittent material application results in a high liquid level in the container 1750 at the supply position. A liquid level holding device 1710 undergoes planar movement (e.g., translation or rotation) between a first position 1742 and a second position 1744, resulting in a uniform liquid surface in the region of the container 1750 between the first position 1742 and the second position 1744. The bottom surface of the liquid level holding device 1710 is configured to maintain a predetermined distance from the bottom (e.g., membrane) of the container 1750, and the liquid level holding device 1710, for example, has no through-holes allowing material to pass through. Through the planar movement of the liquid level holding device 1710, the liquid level in a portion of the container 1750 (e.g., the area between the first position 1742 and the second position 1744) is equal to the aforementioned predetermined distance, while the liquid level in the container 1750 at the supply position is higher than the aforementioned predetermined distance. For example, the liquid level 1752 in the area between the first position 1742 and the second position 1744 of the container 1750 is 300 μm, and the liquid level 1751 in the container 1750 at the supply position is 700 μm.

[0199] A material supply device 1730 may also be provided to supply material to container 1750 from another supply location. Material supply devices 1720 and 1730 supply material to container 1750, and a liquid level holding device 1710 translates between a first position 1742 and a second position 1744, such that the liquid level 1751 at the first supply position and the liquid level 1753 at the second supply position are higher than the liquid level 1752 of the target area. The target area is, for example, the area between the first position 1742 and the second position 1744. During printing, the cured material is located in the target area.

[0200] Figure 18 illustrates an embodiment of maintaining a printing liquid level. As shown in Figure 18, the additive manufacturing system includes a container 1850 and a liquid level maintaining device 1810. The liquid level maintaining device 1810 is provided with a material channel 1812 and at least one opening 1814 in fluid communication with the material channel 1812. The material channel 1812 of the liquid level maintaining device 1810 is connected to a material supply device (not shown) such that the material supply device supplies material to the container 1850 via the material channel 1812 and at least one opening 1814. The liquid level maintaining device 1810 is movable in a horizontal plane and is capable of delivering material to the container during movement to maintain the liquid level in the container 1850 substantially at a predetermined value or within a predetermined range.

[0201] The material channel 1812 shown in Figure 18 is formed by machining or molding. In other embodiments, the material channel is in the form of a pipe and is located outside the liquid level holding device.

[0202] Figure 19 illustrates some embodiments of maintaining printing liquid levels. As shown in Figure 19, the additive manufacturing system includes a plate-shaped carrier 1950 and a liquid level holding device 1910. Compared to a box-type carrier (or container), the plate-shaped carrier does not have sidewalls for containing material. The plate-shaped carrier 1950 shown in Figure 19 includes a transparent membrane and a clamping assembly for holding the membrane.

[0203] The level holding device 1910 is provided with a material channel 1912 and at least one opening 1914 in fluid communication with the material channel 1912. The material channel 1912 of the level holding device 1910 is connected to a material supply device (not shown), such that the material supply device supplies material to the plate-shaped support device 1950 via the material channel 1912 and at least one opening 1914. The level holding device 1910 moves on a horizontal plane and is capable of conveying material to the container during movement to maintain the liquid level 1952 on the plate-shaped support device 1950 substantially at a predetermined value or within a predetermined range. It is understood that the material applied to the membrane by the level holding device 1910 does not have a uniform liquid level over the entire area of ​​the membrane, but only a uniform liquid level in a portion of the membrane (e.g., the central region). The amount of material applied by the level holding device 1910, the properties of the material, and the associated process parameters do not allow material to leave the plate-shaped support device 1950 (which could lead to contamination of the equipment).

[0204] Figure 20 illustrates some embodiments of maintaining a printing liquid level. As shown in Figure 20, the additive manufacturing system includes a plate-shaped carrier 2050, a material supply device 2030, and a liquid level holding device 2010. The material supply device 2030 is, for example, in the form of a nozzle. The material supply device 2030 and the plate-shaped carrier 2050 are movable relative to each other, such that the material supply device 2030 can supply material to any position on the plate-shaped carrier 2050. After the material supply device 2030 supplies material to the plate-shaped carrier 2050, the liquid level holding device 2010 can move in a horizontal plane to flatten and hold the material on the carrier 2050 at a predetermined height (or “predetermined liquid level” 2052). In some embodiments, the material supply device 2030 is movable relative to the plate-shaped carrier 2050, such that the material supply device 2030 allows material to be supplied to a desired position on the carrier 2050, and then the liquid level holding device 2010 moves to flatten the material and hold it at the predetermined height. In some embodiments, the liquid level holding device is omitted, and the material supply device 2030 is movable relative to the plate-shaped support device 2050. The material supply device 2030 supplies material to multiple locations on the support device 2050, and the supplied material flows naturally and leveles. The liquid level holding device helps to accelerate the leveling of the material and prevents the liquid on the support device from sinking (which could lead to an incomplete cured layer).

[0205] Figure 21 illustrates an embodiment of maintaining a printing liquid level. As shown in Figure 21, the additive manufacturing system includes a carrier 2150, a material supply device 2130, and a liquid level holding device 2110. At least one material supply device 2130 supplies material to the carrier 2150, and then the liquid level holding device 2110 moves on a horizontal plane to level the material and hold it at a predetermined height. The carrier 2150 shown in Figure 21 includes a collection container 2154 into which excess material pushed by the liquid level holding device 2110 falls at position K1. The carrier 2150 shown in Figure 21 may also include a collection container 2156 into which excess material pushed by the liquid level holding device 2110 falls at position K2. The carrier 2150 shown in Figure 21 is a single unit.

[0206] Figure 22 illustrates an embodiment of maintaining the printing liquid level. As shown in Figure 22, the additive manufacturing system includes a carrier 2250, a material supply device 2230, a liquid level holding device 2210, and at least one collection container 2270, 2280. At least one material supply device 2230 supplies material to the plate-shaped carrier 2250, and then the liquid level holding device 2210 moves horizontally to level the material and hold it at a predetermined height. Excess material pushed by the liquid level holding device 2210 falls into the collection container 2270 at position K1, and excess material pushed by the liquid level holding device 2210 falls into the collection container 2280 at position K2. It is understood that the carrier 2250 shown in Figure 22 is separate from the collection containers 2270, 2280.

[0207] Figures 23A-23C illustrate embodiments of maintaining printing liquid levels. As shown in Figure 23A, the additive manufacturing system includes a box-shaped carrier 2350, a material supply device 2330, and a liquid level holding device 2310, with some components of the additive manufacturing system (e.g., optical units and forming platforms) concealed. The liquid level holding device 2310 is movable toward or away from the carrier 2350, for example, along the Z-direction. The liquid level holding device 2310 is movable in a horizontal plane perpendicular to the Z-direction, for example, translating along the X-direction perpendicular to the Z-direction, or rotating in a direction perpendicular to the Z-direction. For example, through the material supply from the material supply device 2330 and the translation of the liquid level holding device 2310 along the X-direction, the liquid level of the material in the carrier 2350 is h1 (referring to the liquid level of the material in the subsequently exposed area). h1 is, for example, 200 μm to 1000 μm, for example, 300 μm to 700 μm. When two or more materials are used to solidify an object, the liquid level h1 at least helps to reduce the difficulty of cleaning (for example, see the example shown in Figure 14).

[0208] Figure 23B shows the liquid level holding device 2310 at another height. The additive manufacturing system also includes a drive mechanism (not shown) for driving the liquid level holding device 2310 to move in the Z direction. The drive mechanism drives the liquid level holding device 2310 to move in the Z direction closer to the carrier device 2350, and then the liquid level holding device 2310 translates in the X direction to make the liquid level of the material in the carrier device 2350 h2 (referring to the liquid level of the material in the area to be subsequently exposed). h2 is, for example, 50 μm to 500 μm, for example, 100 μm to 200 μm. It is understood that when it is necessary to cure the material at a liquid level h1, the liquid level holding device 2310 is first used to maintain the liquid level h2 (less than h1), and then the liquid level holding device 2310 is raised and the liquid level h1 is maintained in preparation for curing. A liquid level h2 lower than the liquid level h1 is at least beneficial to reducing the number of air bubbles in the material, and therefore beneficial to ensuring the quality of the object formed at the liquid level h1.

[0209] Figure 23C shows the liquid level holding device 2310 at another height. A drive mechanism moves the liquid level holding device 2310 away from the carrier device 2350 along the Z direction, and then the liquid level holding device 2310 translates along the X direction to bring the liquid level of the material in the carrier device 2350 to h3 (referring to the liquid level of the material in the area to be subsequently exposed). h3 is, for example, 800 μm to 3000 μm, or, for example, 1000 μm to 2000 μm. It is understood that some layers of some objects involve at least two materials, while the remaining layers of these objects involve only a single material (e.g., refer to layers 1031, 1032, 1033 in Figure 10). When multiple layers are formed continuously with a single material, the cleaning step of the formed object can be omitted, and the liquid level can be increased. Curing at a liquid level h3 above the liquid level h1 is at least beneficial in reducing the number of air bubbles in the material, and therefore beneficial in ensuring the quality of the formed object.

[0210] The liquid level holding device 2310 shown in Figures 23A-23C can remain at any distance from the membrane of the carrier device 2350, for example, 0 to 8000 μm. To ensure accuracy, for example, along the Z-direction, the liquid level holding device can be equipped with a detection element such as a height sensor. The liquid level holding device 2310 can contact the membrane of the carrier device 2350, which at least facilitates the calibration of the height positioning of the liquid level holding device 2310 based on a force sensor. The liquid level holding device 2310 can even press down on the membrane of the carrier device 2350 along the Z-direction (e.g., causing a portion of the horizontal membrane to be recessed by 20 μm) and move horizontally along the X-direction, which at least facilitates cleaning, collecting, or gathering material on the membrane of the carrier device 2350.

[0211] Figures 17-22 and 23A-23C show the configuration of only a single carrier device, but at least two carrier devices for an additive manufacturing system can be configured in the same or similar manner.

[0212] Figures 24A-24D illustrate some embodiments of the cleaning unit. The additive manufacturing system includes a molding platform 2410 on which an object 2430 composed of two materials is adhered. Before the next material curing, the molding platform 2410 moves to a cleaning position to clean the formed object 2430.

[0213] The cleaning unit shown in Figure 24A includes a base 2478 and an absorbent layer 2472, which is in the form of, for example, cloth or sponge, and is capable of at least partially absorbing liquid or paste-like material adhering to the object 2430 when it comes into contact with the absorbent layer 2472. For example, a molding platform 2410 carrying the object 2430 moves along the direction of the arrow shown in Figure 24A to approach and contact (or even press down) the absorbent layer 2472, and the liquid material on the object 2430 enters into the micropores of the absorbent layer 2472 (i.e., is absorbed). It is understood that the absorbent layer 2472 can be held or secured to the base 2478 in a variety of ways, such as by tethers, screws, tape, etc. In some embodiments, the absorbent layer 2472 is removable and / or replaceable.

[0214] The cleaning unit shown in Figure 24B includes a base 2478, a first absorbent layer 2472, and a second absorbent layer 2474. The first absorbent layer 2472 and the second absorbent layer 2474 are made of different materials, for example. For instance, the first absorbent layer 2472 may consist of fabric, and the second absorbent layer 2474 may consist of a sponge. When the forming platform 2410 carrying the object 2430 moves along the direction of the arrow shown in Figure 24B and approaches and contacts (or even presses down on) the first absorbent layer 2472, liquid material on the object 2430 enters the micropores of the absorbent layer 2472 (i.e., is absorbed). In some embodiments, the cleaning unit includes at least one first absorbent layer 2472 and / or at least one second absorbent layer 2474.

[0215] The cleaning unit shown in Figure 24C includes a base 2478, a first absorption layer 2472, a second absorption layer 2474, and a heating element 2476. The heating element 2476 is used to raise the temperature of the first absorption layer 2472 and / or the second absorption layer 2474, at least causing a change in the viscosity of the liquid material absorbed by the first absorption layer 2472 and / or the second absorption layer 2474, thereby facilitating absorption by the absorption layers. It can be understood that in some scenarios, a portion of the heat generated by the heating element 2476 is transferred to the uncured liquid material on the object 2430; the increased temperature causes a decrease in the viscosity of the liquid material, thereby facilitating absorption by the absorption layers. The heating element 2476 allows the absorption layers to be heated to a specified temperature or a specified temperature range. The aforementioned specified temperature or specified temperature range is related to the viscosity-temperature relationship of the liquid material. The heating element 2476 is, for example, a PTC heating element.

[0216] The cleaning unit shown in Figure 24D includes a base 2478, a first absorbent layer 2472, a second absorbent layer 2474, and a negative pressure assembly 2476. The negative pressure assembly 2476 provides negative pressure to the first absorbent layer 2472 and / or the second absorbent layer 2474, allowing air to pass through the first and second absorbent layers 2472 and enter the negative pressure assembly 2476. It is understood that the negative pressure assembly 2476 facilitates the flow of liquid material from the object 2430 within the first and second absorbent layers 2472 and 2474 (i.e., improving cleaning efficiency). In some embodiments, the negative pressure assembly 2476 also collects the liquid material flowing through the first and second absorbent layers 2472 and 2474. The negative pressure assembly 2476 is mounted, for example, such that the absorbent layers 2472 and 2474 are arranged between the object 2430 and the negative pressure assembly 2476.

[0217] In a variant of the embodiment shown in Figure 24D, the negative pressure component is replaced by a positive pressure component (with a different installation location). For example, at least one positive pressure component applies airflow to the object 2430 to blow off any uncured liquid material thereon, and this at least one positive pressure component also applies airflow to the absorbent layers to facilitate the flow of liquid material from the object 2430 through the first absorbent layer 2472 and the second absorbent layer 2474 (i.e., improving cleaning efficiency). Additionally, a separate container may be provided to collect the liquid material flowing through the first absorbent layer 2472 and the second absorbent layer 2474.

[0218] It is understood that the cleaning unit may include at least one of the aforementioned absorbent layer, negative pressure assembly, heating element, or positive pressure assembly. These components or assemblies work on liquid materials or absorbent layers on objects.

[0219] Figures 25A-25D illustrate a portion of an additive manufacturing system according to some embodiments. As shown in Figure 25A, the additive manufacturing system includes a liquid level holding device (or actuator) 2510 and a carrier unit 2530. Schematably, the carrier unit 2530 includes three carrier devices 2531, 2532, and 2533, each carrying a different material. For example, the first carrier device 2531 is used to hold a gray resin material M1, the second carrier device 2532 is used to hold a blue resin material M2, and the third carrier device 2533 is used to hold a transparent resin material M3. Correspondingly, the actuator 2510 includes three leveling members 2514, 2516, and 2518. The first leveling member 2514 is capable of maintaining at least a portion of the material M1 carried by the first carrier device 2531 at a predetermined liquid level, for example, 200 μm. The second leveling member 2516 is capable of maintaining at least a portion of the material M2 carried by the second carrier device 2532 at the same predetermined liquid level, for example, 200 μm. The third leveling component 2516 enables at least a portion of the material M3 carried by the third bearing device 1733 to be kept at the same predetermined liquid level, for example, 200 μm.

[0220] In the embodiments shown in Figures 25A-25D, the actuator 2510 further includes a connector 2512 to which three leveling components 2514, 2516, and 2518 are connected or fixed, allowing the three leveling components to move synchronously (e.g., synchronously raise or synchronously translate). It will be understood that in other embodiments, the three leveling components move independently, for example, via a connecting rod for each leveling component, which is driven by a drive mechanism. For example, upon receiving a signal, only a single leveling component is controlled to raise or translate.

[0221] Both the actuator 2510 and the carrier unit 2530 are located on the support assembly 2550 and can move together with the support assembly 2550 (e.g., translate along the direction in which the three carriers are arranged). For example, after material M1 carried by the first carrier 2531 has been cured, material M3 carried by the third carrier 2533 will be cured. At this time, a first drive mechanism (e.g., an electric motor, not shown) drives the support assembly 2550 and the actuator 2510 and carrier unit 2530 thereon to translate together, so as to align the optical unit, the third carrier 2533 and the forming platform of the additive manufacturing system. After alignment, a second drive mechanism drives the forming platform to move in preparation for the subsequent curing step.

[0222] Figures 25A and 25B illustrate actuators in different positions. For example, if the direction in which the three support devices are arranged is defined as a first direction, then actuator 2510 can move from the position shown in Figure 25A to the position shown in Figure 25B along a second direction perpendicular to the first direction. Figures 25A and 25B show three leveling components moving synchronously with the actuator. In other embodiments, at least one of the three leveling components is independently driven and capable of movement along the aforementioned second direction. In other embodiments, one of the three leveling components is independently driven and capable of movement along the aforementioned first direction (this requires changing the arrangement orientation of the leveling components, for example, arranging a single leveling component to extend along the second direction).

[0223] Figure 25C illustrates a lifting mechanism for the actuator. The lifting mechanism 2520 is capable of driving the actuator 2510 to move along a third direction (Z direction), which is perpendicular to the first and second directions. The lifting mechanism 2520 allows the actuator 2510 to remain at different horizontal heights, and the different heights of the actuator 2510 (or leveling member) allow the material carried by the support device to maintain different liquid levels or heights. For example, the first leveling member 2514 of the actuator 2510 translates along the second direction, causing at least a portion of the material M1 carried by the first support device 2531 to be maintained at a predetermined liquid level, such as 200 μm. Then, the lifting mechanism 2520 drives the actuator 2510 to rise, and the second leveling member 2516 translates along the second direction, causing at least a portion of the material M2 carried by the second support device 2532 to be maintained at another predetermined liquid level, such as 400 μm. Then, the third leveling component 2516 translates along the second direction, so that at least a portion of the material M3 carried by the third bearing device 2533 is maintained at another predetermined liquid level, for example, 1000 μm.

[0224] In Figure 25C, the lifting mechanism 2520 includes a drive mechanism (e.g., an electric motor or cylinder) 2522 and an optional flange element 2524. The lifting mechanism 2520 is connected to at least one support rod 2511, 2513 of the actuator 2510, which is raised or lowered as the drive mechanism 2522 operates. Figure 25C shows only a portion of the lifting mechanism 2520 and the actuator 2510.

[0225] Figure 25D illustrates a single leveling component. The leveling component 2514 includes a connecting portion 25142 for connection with a connector 25142, and a body portion 25144 for at least maintaining a predetermined liquid level. In some embodiments, the connecting portion 25142 is omitted, and the body portion 25144 is integrally formed with the connector 2512. In some embodiments, the leveling component 2514 also includes a mating hole 25143, for example, in the form of a threaded hole, which facilitates further reinforcement of the connection between the leveling component 2514 and the connector 2512 by conventional fasteners (e.g., screws).

[0226] In some embodiments, the leveling member 2514 includes at least one through-hole 25146, which is disposed in the upper portion of the leveling member 2514, for example, within 20% to 95% of the height of the leveling member, for example, within 30% to 80% of the height of the leveling member, for example, within 40% to 75% of the height of the leveling member. This allows excess material applied to the support device to overflow from one side of the leveling member 2514 to the opposite side via the through-hole 25146. Correspondingly, the lower portion of the leveling member does not allow material to flow through it.

[0227] It is understandable that the function of the leveling component is at least to maintain a preset liquid level, but the specific implementation is influenced by other factors. In some scenarios, a predetermined amount of material is supplied in a box-type support device. After the material naturally levels, the average liquid level of the entire material area is 600 μm. To achieve the desired liquid level of 400 μm, the leveling component is driven to move to a height of 400 μm from the support device, and then moves (translation or rotation, e.g., reciprocating) on ​​a horizontal plane so that the liquid level in a portion of the material area (e.g., the middle portion) is essentially maintained at 400 μm, while the liquid level in the remaining portion of the material area (e.g., the two sides surrounding the middle portion) is higher than 600 μm. During this process, no material flows through the leveling component (regardless of whether the leveling component has through holes 17146), and material above 400 μm is pushed and temporarily accumulated in the undesirable area (e.g., the two sides). Due to the natural leveling of the material, the temporarily accumulated higher material (above 600 μm) tends to flow towards the lower material region (400 μm), but the higher material only flows to the desired region after a predetermined time period (e.g., 5 s to 30 s, depending at least on the material viscosity and the size of the support device). While the higher material has not flowed to the desired region, a portion of the material in the desired region is exposed and cured according to a predetermined pattern.

[0228] In other scenarios, a predetermined amount of material is supplied to a box-type support device. After the material naturally levels, the average liquid level across the entire material area is approximately 400 μm (e.g., 410 μm). To achieve the desired liquid level of 400 μm, a leveling component is driven to move to a height of 400 μm from the support device and then moves (translation or rotation, e.g., reciprocating) on ​​a horizontal plane so that the liquid level in a portion of the material area (e.g., the middle portion) is substantially maintained at 400 μm, while the liquid level in the remaining portion of the material area (e.g., the portions surrounding the middle portion) is slightly higher than 400 μm. During this process, no material flows through the leveling component (regardless of whether the leveling component has through-holes 25146).

[0229] In other scenarios, a predetermined amount of material is supplied within a box-type support device. Without waiting for the material to level naturally, a leveling component is directly driven to a height of 400 μm from the support device, and then moves (translated or rotated, e.g., reciprocating) on ​​a horizontal plane to maintain the liquid level at approximately 400 μm in a portion of the material area (e.g., the middle section), while the liquid level in the remaining portion of the material area (e.g., the two sides surrounding the middle section) is above 400 μm. During this process, if the leveling component has through-holes 17146, the material will flow through these through-holes and overflow to the opposite side where there is no material. This facilitates replenishing material in the material-free area to subsequently maintain the predetermined liquid level.

[0230] In some embodiments, the location of the through-hole of the leveling component is designed. If the through-hole of the leveling component is located in the lower portion, for example within 5% to 20% of the height of the leveling component, the leveling component moving on the horizontal plane will allow material to move from the through-hole in the lower portion to the other side, which is not conducive to maintaining the predetermined liquid level because the pushed material cannot accumulate in the undesired area.

[0231] It is understood that the leveling component in the foregoing embodiments is capable of reciprocating motion to achieve a predetermined liquid level. The amount of material supplied to the support device, as well as the construction and movement of the leveling component, are adjustable, and these configurations work together to achieve a predetermined liquid level in the desired material region.

[0232] Figure 26 illustrates some embodiments of the cleaning unit. The cleaning unit includes a fabric source 2610 with fabric rolled up and a conveying mechanism for the fabric. The conveying mechanism includes, for example, multiple rollers 2631, 2632, 2633, 2634, 2635 (at least one of which is an active roller) for continuously conveying the fabric to a base 2650 (or a cleaning position). The direction of fabric conveying is indicated by arrows in Figure 26. In some examples, a forming platform 2671 carries the object to be cleaned toward the base 2650 and cleans it at the cleaning position (e.g., uncured material on the object to be cleaned is at least adsorbed or absorbed by the fabric). After at least one (e.g., one, two, ten, twenty) cleanings, a new fabric is needed to maintain the cleaning effect. At this time, the conveying mechanism removes the used fabric from the cleaning position and conveys a new fabric to the cleaning position for subsequent cleaning. In some embodiments, a sponge or other absorbent material is also provided on the base 2650. In some embodiments, other cleaning components are available, such as the examples shown in Figures 24A-24D.

[0233] In this document, unless otherwise specified, the terms "first material" and "second material" refer to different types of materials. It is understood that the terms "first material" or "second material" can refer to a material having a single component or a mixture of multiple components.

[0234] The terms "tray" or "carrying device" as used herein can be configured in a variety of ways. In some embodiments, the tray includes multiple boxes in which liquid or paste-like material is contained. In some embodiments, the tray includes multiple plate-like elements on which liquid or paste-like material is applied. In some embodiments, the tray includes at least one box and at least one plate-like element. The forming platform is sized to allow it to fall into the printing area of ​​the respective tray (e.g., box or plate-like element).

[0235] The terms “forming platform” and “tray” used herein should be understood as horizontal. In the event that a forming platform or tray is not horizontal due to manufacturing or layout errors, it also falls within the scope of protection of this application.

[0236] The terms “leveling unit” and “liquid leveling device” used herein are interchangeable in some embodiments.

[0237] The various components or elements in the embodiments shown herein can be combined with each other without causing contradiction. Embodiments obtained through such combinations also fall within the scope of this document.

[0238] The description in this application is merely exemplary in nature, and therefore, variations intended without departing from the essence of this application are within its scope. Such variations should not be considered as departing from the spirit and scope of this application.

Claims

1. A three-dimensional printing method for manufacturing a target object, characterized in that, The 3D printing method includes: A first material container having a first printing area is provided, and a first portion of a first layer is formed by radiating the first printing area to cure a first material and form a first layer having a first thickness. A second material container with a second printing area is provided, and radiation is applied to the second printing area to cure a second material and form a second portion of a first layer, the second portion of the first layer having a second thickness. During the radiation, the liquid levels in the first and second material containers are maintained at 40 μm to 950 μm, and are more than 1.2 times the second thickness.

2. The three-dimensional printing method according to any one of the preceding claims, wherein, The liquid level in the first material container and the second material container is 1.5 to 20 times the second thickness, preferably 1.8 to 8 times, more preferably 2 to 6 times, and even more preferably 3 to 5 times.

3. The three-dimensional printing method according to any one of the preceding claims, wherein, The liquid levels in the first and second material containers are 100 μm to 800 μm.

4. The three-dimensional printing method according to any one of the preceding claims, wherein, The liquid level in the first and second material containers is 120μm to 700μm, preferably 150μm to 600μm, more preferably 180μm to 500μm, and even more preferably 200μm to 400μm.

5. The three-dimensional printing method according to any one of the preceding claims, wherein, The second part of the first layer is formed on the first part of the first layer.

6. The three-dimensional printing method according to any one of the preceding claims, wherein, Along the construction direction or Z-axis direction of the target object, the first part of the first layer and the second part of the first layer at least partially overlap.

7. The three-dimensional printing method according to any one of the preceding claims, wherein, The first thickness of the first portion of the first layer is equal to the second thickness of the second portion of the first layer.

8. The three-dimensional printing method according to any one of the preceding claims, wherein, The second thickness of the second part of the first layer is greater than the first thickness of the first part of the first layer.

9. The three-dimensional printing method according to any one of the preceding claims further includes: Radiation is directed toward the first printing area to solidify the first material, thereby forming a first portion of the second layer on a first portion of the first layer, such that the total thickness of the first portion composed of the first material is greater than the total thickness of the second portion composed of the second material. Then, The second material is radiated to the second printing area to cure the second material, thereby forming a second portion of the second layer on the second portion of the first layer, such that the total thickness of the second portion composed of the second material is greater than the total thickness of the first portion composed of the first material.

10. The three-dimensional printing method according to any one of the preceding claims further includes: Clean the solidified parts of the target object.

11. The three-dimensional printing method according to any one of the preceding claims, wherein the cleaning includes at least one of the following: rotating the target object, wiping the target object, applying an airflow to the target object, and surrounding the target object with an adsorption element.

12. The three-dimensional printing method according to any one of the preceding claims, wherein, After forming the first part of the first layer, clean the solidified part of the target object; and / or After the second part of the first layer is formed, the solidified part of the target object is cleaned.

13. The three-dimensional printing method according to any one of the preceding claims, wherein, The solidified portion of the target object includes: -Basic parts; and - Adhere to at least one of the first or second parts of the first layer of the base portion.

14. A three-dimensional printing system for manufacturing a target object, characterized in that, The 3D printing system includes: A first material container, which includes a first printing area and contains a first material; A second material container, which includes a second printing area and contains a second material different from the first material; An optical unit configured to project light onto a first printing area or a second printing area; A processor configured to determine the thickness of the portion to be cured; During the projection of the light, the liquid level in the first and second material containers is maintained at 40 μm to 950 μm, which is more than 1.2 times the thickness of the part to be cured.

15. An additive manufacturing system comprising: The first supporting device is configured to support the first material; A forming platform configured to move along a first direction to approach or move away from a first support device; A first actuator for a first bearing device is movable between a first height level and a second height level, wherein... - At the first height level, the first actuator is configured to move in a second direction perpendicular to the first direction to allow at least a portion of the first material carried by the first bearing device to remain at the first predetermined height; - At a second height level, different from the first height level, the first actuator can move in a second direction; and An optical unit configured to project light onto a first material at a first predetermined height to allow the first material to cure based on a preset pattern.

16. The additive manufacturing system according to any one of the preceding claims, wherein the first support device is formed as a plate-shaped element or a box-shaped element.

17. The additive manufacturing system according to any one of the preceding claims, wherein, When the first support device is formed as a plate-shaped element, the first actuator is configured to move in a second direction so that all the first material carried by the first support device is kept at a first predetermined height.

18. The additive manufacturing system according to any one of the preceding claims, wherein, The first carrier includes at least one collection container configured to collect a first material propelled by a first actuator.

19. The additive manufacturing system according to any one of the preceding claims, wherein, The additive manufacturing system includes at least one collection container configured to be spaced apart from the first support device and to collect first material propelled by the first actuator.

20. The additive manufacturing system according to any one of the preceding claims, wherein, When the first support device is formed as a box-shaped element, the first actuator is configured to move in a second direction so that a portion of the first material carried by the first support device is held at a first predetermined height, and the remaining portion of the first material carried by the support device is above the first predetermined height.

21. The additive manufacturing system according to any one of the preceding claims, wherein, The first actuator includes a lower portion configured to prevent the flow of the first material through the lower portion.

22. The additive manufacturing system according to any one of the preceding claims further includes a first feeding mechanism configured to supply the first material to the first support device.

23. The additive manufacturing system according to any one of the preceding claims, wherein, The first feeding mechanism is configured to be stationary or movable relative to the first supporting device.

24. The additive manufacturing system according to any one of the preceding claims, wherein, - The second altitude level is higher than the first altitude level; or - The second altitude level is lower than the first altitude level.

25. The additive manufacturing system according to any one of the preceding claims, wherein, The first actuator is configured to move between a first altitude level, a second altitude level, and a third altitude level, wherein the first altitude level is between the second altitude level and the third altitude level.

26. The additive manufacturing system according to any one of the preceding claims, wherein, The first predetermined height is 50μm to 1000μm, for example 100μm to 800μm, for example 200μm to 500μm, for example 300μm to 400μm.

27. The additive manufacturing system according to any one of the preceding claims further includes a cleaning unit configured to separate an uncured first material adhering to a cured object on a molding platform from the cured object.

28. The additive manufacturing system according to any one of the preceding claims, wherein the cleaning unit comprises at least one of an airflow assembly, a wiping assembly, an adsorption assembly, a cleaning container, a spraying assembly, or a heating assembly.

29. The additive manufacturing system according to any one of the preceding claims further includes a second support device configured to support a second material, wherein the second material is different from the first material.

30. The additive manufacturing system according to any one of the preceding claims further includes a second actuator for the second support device, the second actuator being movable to different height levels along the first direction.

31. An additive manufacturing method, comprising: The molding platform is moved along the first direction to move closer to or further away from the first support device; Keep the first executive body at the first altitude level; When the first actuator is at the first height level, it is driven to move in a second direction perpendicular to the first direction, so that at least a portion of the first material carried by the first bearing device is kept at the first predetermined height; Using an optical unit, light is projected onto a first material at a first predetermined height to allow the first material to cure based on a preset pattern; and Drive the first actuator to move along the first direction to a second height level different from the first height level.

32. The additive manufacturing method according to any one of the preceding claims further comprises: When the first actuator is at the second height level, the first actuator is driven to move in the second direction so that at least a portion of the first material carried by the first bearing device is kept at the second predetermined height, the second predetermined height being lower than the first predetermined height; Drive the first actuator to move along a first direction from a second height level to a first height level; and Using an optical unit, light is projected onto a first material at a first predetermined height to allow the first material to cure based on a new preset pattern.

33. The additive manufacturing method according to any one of the preceding claims further comprises: When the first actuator is at the second height level, it is driven to move in the second direction so that at least a portion of the first material carried by the first bearing device is maintained at a third predetermined height, which is higher than the first predetermined height. and Using an optical unit, light is projected onto the first material at a third predetermined height to allow the first material to cure based on a new preset pattern.

34. The additive manufacturing method according to any one of the preceding claims further comprises: After the first material is cured, at least one of the molding platform and the second support device that carries the second material is moved to align the molding platform with the second support device. and Using an optical unit, the second material carried by the second carrier device projects light to cause the second material to solidify based on a new preset pattern.

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