Leveling device for 3D printing

Abstract

A leveling device for a three dimensional printing system includes a rotatable roller, a waste collection tank, a blade for removing liquid waste from the roller into the tank, and a plurality of tubular structures, each having an inlet near a base of the tank and an outlet connectable to a pumping device.

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 015,728, filed Apr. 27, 2020, the content of which is incorporated herein by reference in its entirety.

[0002] In some embodiments, the present invention relates to three-dimensional printing, and more particularly, but not limited thereto, to a leveling device for three-dimensional printing.

Background Art

[0003] Additive manufacturing (AM) is a technology that enables the direct manufacture of structures of arbitrary shape from computer data via additional forming steps. The basic operation of any AM system consists of slicing a three-dimensional computer model into thin cross-sectional parts, converting the result into two-dimensional position data, and supplying this data to a control device that creates the three-dimensional structure in layers.

[0004] Additive manufacturing involves many different approaches to manufacturing methods, including three-dimensional (3D) printing such as 3D inkjet printing. 3D inkjet printing is accomplished by depositing a construction material layer by layer via inkjet printing. Thus, the construction material is ejected from a discharge head having a set of nozzles and deposited in layers on a support structure. The layer is then flattened by a leveling device and cured or solidified.

[0005] There are various three-dimensional printing technologies, for example, disclosed in U.S. Pat. Nos. 6,259,962, 6,569,373, 6,658,314, 6,850,334, 7,183,335, 7,209,797, 7,225,045, 7,300,619, 7,479,510, 7,500,846, 7,962,237, 8,784,723, and 9,031,680, all of the same assignee, the content of which is incorporated herein by reference.

Summary of the Invention

[0006] According to one aspect of several embodiments of the present invention, a leveling device for a three-dimensional printing system is provided. The leveling device comprises a rotatable roller, a motor for rotating the roller, a waste collection tank, blades for removing liquid waste from the roller into the tank, and a plurality of tubular structures. Each tubular structure has an inlet near the base of the tank and an outlet that can be connected to a pumping device.

[0007] According to some embodiments of the present invention, the base is composed of a plurality of separate recessed regions, and the entrance for each tubular structure is located in one of these recessed regions.

[0008] According to some embodiments of the present invention, the base is a non-flat surface having a wavy shape, and the recessed regions are the valleys of the wavy shape.

[0009] According to some embodiments of the present invention, the non-flat surface comprises a plurality of inclined portions that form a wavy shape.

[0010] According to some embodiments of the present invention, the leveling device includes a rotation sensor for generating a signal indicating the rotation of a roller.

[0011] According to some embodiments of the present invention, the rotation sensor comprises a magnetic sensor. According to some embodiments of the present invention, the magnetic sensor comprises a Hall effect sensor.

[0012] According to some embodiments of the present invention, the leveling device comprises a housing that can be connected to a three-dimensional printing system, and at least one of the rollers and the waste collection tank is mounted on the housing.

[0013] According to some embodiments of the present invention, the leveling device includes a position sensor for generating a signal indicating the mounting of a tank to a housing. According to some embodiments of the present invention, the position sensor is a mechanical switch. According to some embodiments of the present invention, the position sensor is an optical sensor.

[0014] According to some embodiments of the present invention, at least one of the rollers and the waste collection tank is detachably attached to the housing by a quick release mechanism.

[0015] According to some embodiments of the present invention, the rapid release mechanism is selected from the group consisting of elastic clip connectors and magnetic connectors.

[0016] According to some embodiments of the present invention, at least one of the tubular structures is formed as a siphon.

[0017] According to one aspect of several embodiments of the present invention, a printing system for three-dimensional printing is provided. This printing system comprises an array of nozzles for dispensing construction material, a leveling device as described above and optionally and preferably detailed below, a pump device connected to the outlet of a tubular structure, and a computerized controller configured to operate at least the nozzle array.

[0018] According to some embodiments of the present invention, the pumping system comprises at least two separate pumps, each connected to the outlets of separate tubular structures. The controller is configured to start and stop each of the pumps individually.

[0019] According to some embodiments of the present invention, the printing system comprises a tray for receiving building material ejected from a nozzle. The width of the working area of ​​the tray is greater than the length of the array, and the length of the rollers is at least the width of the working area.

[0020] According to some embodiments of the present invention, the controller is configured to start and stop each of the pumps based on the position of the array relative to the tray.

[0021] According to some embodiments of the present invention, the leveling device includes a position sensor for generating a signal indicating that the tank is positioned below the roller, and the controller is configured to receive the signal from the position sensor and to generate an alarm or stop the nozzle if the tank is not in the correct position.

[0022] According to some embodiments of the present invention, the leveling device includes a rotation sensor for generating a signal indicating the rotation of a roller, and the controller is configured to receive the signal from the rotation sensor and to generate an alarm or stop the nozzle if the rotation speed is zero or below a predetermined threshold.

[0023] According to some embodiments of the present invention, the leveling device comprises a housing connected to a three-dimensional printing system, and the waste collection tank is detachably attached to the housing by a rapid release mechanism.

[0024] According to one aspect of several embodiments of the present invention, a method for performing maintenance on a printing system is provided. This method includes removing a waste collection tank from the housing, performing at least one maintenance operation while the tank is removed, and attaching the waste collection tank to the housing.

[0025] According to one aspect of several embodiments of the present invention, a method for leveling a construction material layer in three-dimensional printing is provided. This method includes engaging a rotating roller of a leveling device, described above and optionally and preferably detailed below, with the outermost surface of the layer during the relative motion of the roller with the layer, thereby collecting excess construction material into a tank, and operating a pumping device to remove at least a portion of the excess construction material from the tank via at least one tubular structure.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, exemplary methods and / or materials are described below. In case of conflict, the specification of the present invention, including definitions, will control. Further, the materials, methods, and examples are illustrative only and not intended to be limiting necessarily.

[0027] The implementation of the methods and / or apparatuses of embodiments of the present invention may include performing or completing a selected task manually, automatically, or a combination thereof. Further, depending on the actual instrumentation and equipment of the methods and / or apparatus embodiments of the present invention, some selected tasks can be implemented by hardware, or by software or firmware using an operating system and / or a combination thereof.

[0028] For example, the hardware for performing a selected task according to an embodiment of the present invention can be implemented as a chip or a circuit. Regarding software, a selected task according to an embodiment of the present invention can be implemented as a plurality of software instructions executed by a computer using any suitable operating system. In an exemplary embodiment of the present invention, one or more tasks according to the exemplary embodiments of the methods and / or apparatuses described herein are executed by a data processor such as a computing platform that executes a plurality of instructions. Optionally, the data processor includes a volatile memory for storing instructions and / or data, and / or a non-volatile storage device for storing instructions and / or data, such as a magnetic hard disk and / or a removable medium. Optionally, a network connection is also provided. A display and / or user input devices such as a keyboard and a mouse are also optionally provided.

[0029] Some embodiments of the present invention will be described herein by way of example only with reference to the accompanying drawings. Here, referring specifically to the drawings in detail, it is emphasized that the details shown are by way of example and for the purpose of an illustrative discussion of embodiments of the present invention. In this regard, from the description taken in conjunction with the drawings, it will be apparent to those skilled in the art how embodiments of the present invention may be practiced.

Brief Description of the Drawings

[0030] [Figure 1A] It is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention. [Figure 1B] It is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention. [Figure 1C] It is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention. [Figure 1D] It is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention. [Figure 2A] It is a schematic diagram of a print head according to some embodiments of the present invention. [Figure 2B] It is a schematic diagram of a print head according to some embodiments of the present invention. [Figure 2C] It is a schematic diagram of a print head according to some embodiments of the present invention. [Figure 3A] It is a schematic diagram showing coordinate transformation according to some embodiments of the present invention. [Figure 3B] It is a schematic diagram showing coordinate transformation according to some embodiments of the present invention. [Figure 4A] It is a schematic diagram of a leveling device according to some embodiments of the present invention. [Figure 4B] It is a schematic diagram of a leveling device according to some embodiments of the present invention. [[ID=P39]] [Figure 4C] It is a schematic diagram of a leveling device according to some embodiments of the present invention. [Figure 4D] It is a schematic diagram of a leveling device according to some embodiments of the present invention. [Figure 4E]This is a schematic diagram of a leveling device according to several embodiments of the present invention. [Figure 4F] This is a schematic diagram of a leveling device according to several embodiments of the present invention. [Figure 4G] This is a schematic diagram of a leveling device according to several embodiments of the present invention. [Figure 4H] This is a schematic diagram of a leveling device according to several embodiments of the present invention. [Figure 5A] This is a schematic exploded view of the housing, tank, and rollers of a leveling device according to several embodiments of the present invention. [Figure 5B] This is a schematic front view perspective of a beam member that facilitates the integration of a leveling device into a three-dimensional printing system, according to some embodiments of the present invention. [Figure 5C] This is a schematic perspective view of the back of a beam material, which facilitates the integration of a leveling device into a three-dimensional printing system according to some embodiments of the present invention. [Figure 6A] This is a schematic diagram showing the waste collection tank and tubular structure in more detail. [Figure 6B] This is a schematic diagram showing the waste collection tank and tubular structure in more detail. [Figure 6C] This is a schematic diagram showing the waste collection tank and tubular structure in more detail. [Figure 6D] This is a schematic diagram showing the waste collection tank and tubular structure in more detail. [Figure 6E] This is a schematic diagram showing the waste collection tank and tubular structure in more detail. [Figure 6F] This is a schematic diagram showing the waste collection tank and tubular structure in more detail. [Modes for carrying out the invention]

[0031] In some embodiments, the present invention relates to three-dimensional printing, and more specifically, to a leveling device for three-dimensional printing, but is not limited thereto.

[0032] Before describing in detail at least one embodiment of the present invention, it should be understood that the application of the present invention is not necessarily limited to the details of the structure, arrangement and / or method of its components presented in the following description and / or shown in the drawings and / or examples. Other embodiments of the present invention are possible and can be carried out or implemented in a variety of ways.

[0033] The method and system of this embodiment manufacture a three-dimensional object layer by layer by forming multiple layers with a configuration pattern corresponding to the shape of the object based on computer object data. The computer object data may be any known format, but is not limited to, the Standard Tessellation Language (STL) or Stereolithography Contour (SLC) format, OBJ file format (OBJ), 3D Manufacturing Format (3MF), Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Exchange Format (DXF), Polygon File Format (PLY), or any other format suitable for computer-aided design (CAD).

[0034] As used herein, the term “object” refers to the whole or a part of an object.

[0035] Each layer is formed by an additive manufacturing apparatus that scans and patterns a two-dimensional surface. During scanning, the apparatus moves to multiple target locations on the two-dimensional layer, i.e., the surface, and for each target location or group of target locations, it determines whether or not each target location or group of target locations should be covered with building material, and what type of building material should be delivered to them. The decision is made according to a computer image of the surface.

[0036] In preferred embodiments of the present invention, AM comprises three-dimensional printing, more preferably three-dimensional inkjet printing. In these embodiments, a build material is ejected from a printhead having one or more nozzle arrays to deposit the build material in layers onto a support structure. The AM apparatus thus ejects the build material to target locations to be covered with it, leaving other target locations empty. The apparatus typically includes multiple nozzle arrays, each of which can be configured to eject a different build material. This is usually achieved by providing a printhead having multiple fluid channels that are separated from each other and not fluidly communicating with one another. Different build materials flow through each channel via separate inlets and are delivered to separate nozzle arrays.

[0037] Therefore, it is possible to occupy different target locations with different construction materials. Construction materials can be broadly classified into two types: molding materials and support materials. Support materials function as a support matrix or structure to support an object or part of an object during the manufacturing process and / or for other purposes, such as providing a hollow or porous object. Support structures may also include additional molding material elements, for example, to increase support strength.

[0038] Modeling materials are generally compounds formulated for use in additive manufacturing, capable of forming three-dimensional objects on their own, that is, without the need for mixing or combining them with any other substances.

[0039] The final three-dimensional object is made from a molding material, a combination of multiple molding materials, a molding material and a support material, or a deformed version thereof (e.g., after curing). All of these operations are well known to those skilled in the field of solid free forming.

[0040] According to some exemplary embodiments of the present invention, an object is manufactured by extruding two or more different molding materials, each material being extruded from a different nozzle array (of the same or different print heads) of the AM device. In some embodiments, two or more such nozzle arrays extruding different molding materials are all located on the same print head of the AM device. In some embodiments, the nozzle arrays extruding different molding materials are located on separate print heads. For example, a first nozzle array extruding a first molding material is located on a first print head, and a second nozzle array extruding a second molding material is located on a second print head.

[0041] In some embodiments, both the nozzle array for ejecting the build material and the nozzle array for ejecting the support material are located on the same print head. In some embodiments, the nozzle array for ejecting the build material and the nozzle array for ejecting the support material are located on separate print heads.

[0042] Figure 1A shows a representative and non-limiting example of a system 110 suitable for AM of an object 112, according to several embodiments of the present invention. The system 110 comprises an additive manufacturing apparatus 114 having an ejection unit 16 with a plurality of print heads. Each head preferably comprises one or more nozzle arrays 122, typically mounted on an orifice plate 121 as shown in Figures 2A to 2C below, through which a liquid building material 124 is ejected.

[0043] Preferably, but not required, the apparatus 114 is a three-dimensional printing apparatus, in which case the print head is a print head and the building material is ejected via inkjet technology. This is not necessarily required, because in some applications, additive manufacturing apparatuses do not need to use three-dimensional printing technology. Typical examples of additive manufacturing apparatuses intended by various exemplary embodiments of the present invention include, but are not limited to, fused deposition modeling apparatuses and fused material deposition apparatuses.

[0044] Each print head is optionally and preferably supplied via one or more build material tanks, which may optionally include a temperature control unit (e.g., a temperature sensor and / or a heating device) and a material level sensor. To eject the build material, a voltage signal is applied to the print head, as in piezoelectric inkjet printing technology, for example, to selectively deposit droplets of the material through the print head nozzles. Another example is a thermal inkjet print head. In this type of head, there is a heater element that is in thermal contact with the build material, and by activating the heater element with a voltage signal, the build material is heated and gas bubbles are formed therein. The gas bubbles generate pressure in the build material, causing droplets of the build material to be ejected through the nozzles. Piezoelectric and thermal print heads are known to those skilled in the art of solid free-form printing. With respect to any type of inkjet print head, the ejection speed of the head depends on the number of nozzles, the type of nozzles, and the applied voltage signal rate (frequency).

[0045] Preferably, but not required, the total number of ejection nozzles or nozzle arrays is selected such that half of the ejection nozzles are for ejecting the support material and the other half are for ejecting the build material. That is, the number of nozzles ejecting the build material is the same as the number of nozzles ejecting the support material. In a typical example, Figure 1A shows four print heads 16a, 16b, 16c, and 16d. Each head 16a, 16b, 16c, and 16d has a nozzle array. In this example, heads 16a and 16b may be for build material, and heads 16c and 16d may be for support material. Thus, head 16a can eject one build material, head 16b can eject another build material, and both heads 16c and 16d can eject support material. In an alternative embodiment, for example, heads 16c and 16d can be combined to form a single head with two nozzle arrays for depositing support material. In a further alternative embodiment, any one or more print heads may have two or more nozzle arrays for depositing two or more materials. For example, two nozzle arrays for two different build materials, or two nozzle arrays for one build material and one support material, where each formulation is deposited through a different array or a different number of nozzles.

[0046] However, it should be understood that this is not intended to limit the scope of the present invention, and that the number of print heads (build heads) for the build material and the number of print heads (support heads) for the support material may differ. Generally, the number of nozzle arrays for ejecting the build material, the number of nozzle arrays for ejecting the support material, and the number of nozzles in each array are selected to give a predetermined ratio a between the maximum ejection speed of the support material and the maximum ejection speed of the build material. The value of the predetermined ratio a is preferably selected such that the height of the build material and the height of the support material are equal in each layer formed. Typical values ​​of a are from about 0.6 to about 1.5.

[0047] As used throughout this specification, the term “approximately” refers to ±10%.

[0048] For example, when a=1, if all nozzle arrays are operating, the total extrusion rate of the support material is approximately equal to the total extrusion rate of the build material.

[0049] In a preferred embodiment, the system may comprise M build heads, each having m arrays of p nozzles, and S support heads, each having s arrays of q nozzles, where M × m × p = S × s × q. Each of the M × m build arrays and S × s support arrays can be manufactured as a separate physical unit and can be assembled and disassembled from a group of arrays. In this embodiment, each of such arrays optionally and preferably includes its own temperature control unit and material level sensor, which receive individually controlled voltages for their operation.

[0050] The apparatus 114 further comprises a solidification apparatus 324. This may include any apparatus configured to emit light, heat, or the like, which can solidify the deposited material. For example, the solidification apparatus 324 may include one or more radiation sources. Depending on the material being molded, these may be, for example, ultraviolet, visible, or infrared lamps, or other electromagnetic radiation sources, or electron sources. In some embodiments of the present invention, the solidification apparatus 324 performs the function of curing or solidifying the material being molded.

[0051] In addition to the coagulation apparatus 324, the apparatus 114 optionally and preferably comprises an additional radiation source 328 for evaporating the solvent. The radiation source 328 optionally and preferably generates infrared radiation. In some embodiments of the present invention, the coagulation apparatus 324 comprises a radiation source that generates ultraviolet radiation, and the radiation source 328 generates infrared radiation.

[0052] In some embodiments of the present invention, the apparatus 114 includes one or more cooling devices 134, such as fans.

[0053] The print head and radiation source are preferably mounted on a frame or block 128. Preferably, the block 128 is mounted above a tray 360 that serves as a work surface. Here, at least one of the block 128 and the tray 360 moves in a reciprocating motion so that the tray 360 and the block 128 establish relative reciprocating motion. In some embodiments of the present invention, the radiation source is mounted on the block and follows the trajectory of the ejection head to at least partially harden or solidify the material just ejected by the print head. The tray 360 is positioned horizontally. Following common practice, an XYZ Cartesian coordinate system is selected such that the XY plane is parallel to the tray 360. The tray 360 is preferably configured to move vertically (along the Z direction), usually downward. In various embodiments of the present invention, the apparatus 114 further comprises a leveling device 32, which may comprise a roller 420 and optionally, and preferably, a blade 434, as will be described in detail below. The leveling device 32 functions to straighten, flatten, and / or define the thickness of a newly formed layer before the next layer is formed on top of it. The leveling device 32 preferably includes a waste collection tank 432 for collecting excess material generated during leveling. The waste collection tank 432 may include a mechanism for delivering the material to a waste tank or waste cartridge, as will be described in further detail later.

[0054] During use, the print heads of unit 16 move in a scanning direction, referred to herein as the X direction, and selectively eject the build material in a predetermined configuration as they pass over the tray 360. The build material typically includes one or more support materials and one or more build materials. Following the passage of the print heads of unit 16, the build material is cured by the radiation source 126. Additional build material may be ejected according to a predetermined configuration during the reverse movement of the heads back to the starting point of the layer that has been deposited. The layers thus formed can be corrected by the leveling device 32 during the forward or reverse movement of the print heads. This is preferably along the path of the print heads during forward and / or reverse movement. When the print heads return to their starting points along the X direction, they can move to another position along the indexing direction, referred herein as the Y direction, and continue building the same layer by reciprocating motion along the X direction. Alternatively, the print heads may move in the Y direction between forward and reverse movements, or after two or more forward-reverse movements. A series of scans performed by the print head to complete a single layer is referred to herein as a single scan cycle.

[0055] Once that layer is complete, the tray 360 is lowered in the Z direction to a predetermined Z level, depending on the desired thickness of the next layer to be printed. This procedure is repeated until the three-dimensional object 112 is formed layer by layer.

[0056] In another embodiment, the tray 360 may be displaced in the Z direction within the layer during the forward and reverse passage of the print head of unit 16. Such Z displacement is performed to bring the leveling device and the surface into contact in one direction and not in the opposite direction.

[0057] System 110 optionally and preferably includes a construction material supply system 330 which includes a construction material container or cartridge and supplies a plurality of construction materials to the manufacturing apparatus 114.

[0058] The computerized controller 20 controls the manufacturing apparatus 114 and optionally, and preferably, also controls the supply system 330. The controller 20 typically includes electronic circuitry configured to perform control operations. The controller 20 preferably communicates with a data processor 24, which transmits digital data relating to manufacturing instructions based on computer object data, such as CAD configurations represented on a computer-readable medium in a format such as Standard Tessellation Language (STL) format. Typically, the controller 20 controls the voltage applied to each print head or each nozzle array, and the temperature of the construction material in each print head or each nozzle array.

[0059] Once manufacturing data is loaded into the controller 20, the controller can operate without user intervention. In some embodiments, the controller 20 receives additional input from the operator, for example, using a data processor 24 or a user interface 116 that communicates with the controller 20. The user interface 116 may be any type known in the art, such as a keyboard or touchscreen, but is not limited to these. For example, the controller 20 may receive as additional input one or more types of construction materials and / or attributes such as, for example, color, characteristic strain and / or transition temperature, viscosity, electrical properties, magnetic properties, etc. Other attributes and attribute groups may also be considered.

[0060] Another representative and non-limiting embodiment of System 10 suitable for AM of objects according to some embodiments of the present invention is shown in Figures 1B to 1D. Figures 1B to 1D show a plan view (Figure 1B), a side view (Figure 1C), and an isometric view (Figure 1D) of System 10.

[0061] In this embodiment, the system 10 comprises a tray 12 and a plurality of inkjet print heads 16, each having one or more nozzle arrays, each having one or more isolated nozzles. The material used for three-dimensional printing is supplied to the heads 16 by a construction material supply system 42. The tray 12 may be disc-shaped or annular. Non-circular shapes are also possible, as long as they are rotatable about a vertical axis.

[0062] The tray 12 and the head 16 are optionally and preferably mounted to allow relative rotational motion between the tray 12 and the head 16. This can be achieved by (i) a configuration in which the tray 12 rotates relative to the head 16 about a vertical axis 14, (ii) a configuration in which the head 16 rotates relative to the tray 12 about a vertical axis 14, or (iii) a configuration in which both the tray 12 and the head 16 rotate about a vertical axis 14, but at different rotational speeds (e.g., in opposite directions). In the following, several embodiments of the system 10 will be described with particular emphasis on configuration (i), which is a rotating tray configured to rotate relative to the head 16 about a vertical axis 14, but it should be understood that this application also intends for configurations (ii) and (iii) with respect to the system 10. Any embodiment of the system 10 described herein can be adapted to be applicable to either configuration (ii) or configuration (iii), and such adaptations will be apparent to those skilled in the art given the details described herein.

[0063] In the following explanation, the direction parallel to tray 12 and outward from axis 14 will be called the radial direction r, the direction parallel to tray 12 and perpendicular to radial direction r will be called the azimuth direction φ, and the direction perpendicular to tray 12 will be called the vertical direction z.

[0064] The radial direction r of system 10 defines the indexing direction y of system 110, and the azimuth direction φ defines the scanning direction x of system 110. Therefore, the radial direction is interchangeably referred to as the indexing direction in this specification, and the azimuth direction is interchangeably referred to as the scanning direction in this specification.

[0065] As used herein, the term "radial position" refers to a position on or above the tray 12 at a specific distance from the axis 14. When used in relation to a print head, the term refers to a position of the head at a specific distance from the axis 14. When used in relation to a point on the tray 12, the term corresponds to any point that belongs to the locus of a circle whose radius is at a specific distance from the axis 14 and whose center is on the axis 14.

[0066] As used herein, the term "azimuth position" refers to a position on or above the tray 12 that is at a specific azimuth angle with respect to a predetermined reference point. Therefore, the radial position refers to any point that belongs to the locus of points that form a straight line making a specific azimuth angle with respect to the reference point.

[0067] As used herein, the term "vertical position" refers to a position on a plane that intersects the vertical axis 14 at a specific point.

[0068] Tray 12 functions as a build platform for three-dimensional printing. The work area on which one or more objects are printed is usually smaller than the total area of ​​tray 12, but not necessarily. In some embodiments of the present invention, the work area is annular. The work area is indicated by reference numeral 26. In some embodiments of the present invention, tray 12 rotates continuously in the same direction during the formation of an object, and in some embodiments of the present invention, the tray reverses its direction of rotation at least once (e.g., to vibrate) during the formation of an object. Tray 12 is optionally and preferably removable. Removal of tray 12 can be done for maintenance of system 10 or, if desired, to replace the tray before printing a new object. In some embodiments of the present invention, system 10 is provided with one or more different replacement trays (e.g., a kit of replacement trays), and two or more trays are selected for different types of objects (e.g., different weights), different operating modes (e.g., different rotation speeds), etc. Replacement of tray 12 can be manual or automatic, as desired. When automatic replacement is used, the system 10 includes a tray changer 36 configured to remove the tray 12 from its position below the head 16 and replace it with a replacement tray (not shown). In the representative figure of Figure 1B, the tray changer 36 is shown as a drive unit 38 having a movable arm 40 configured to pull the tray 12, but other types of tray changers are also possible.

[0069] Exemplary embodiments of the print head 16 are shown in Figures 2A to 2C. These embodiments are not limited to those described above and can be used in any AM system including system 110 and system 10.

[0070] Figures 2A and 2B show a print head 16 having one (Figure 2A) and two (Figure 2B) nozzle arrays 22. The nozzles in the arrays are preferably arranged linearly along a straight line. In embodiments in which a particular print head has two or more linear nozzle arrays, the nozzle arrays may optionally and preferably be parallel to each other. When a print head has two or more nozzle arrays (for example, Figure 2B), all arrays in the head may be supplied with the same building material, or at least two arrays in the same head may be supplied with different building materials.

[0071] When a system similar to system 110 is used, all print heads 16 are optionally and preferably oriented along the indexing direction, and their positions along the scanning direction are offset from one another.

[0072] When a system similar to system 10 is used, all print heads 16 are optionally and preferably oriented radially (parallel to the radial direction), and their azimuth positions are offset from one another. Thus, in these embodiments, the nozzle arrays of different print heads are not parallel to each other, but rather form an angle with each other. This angle is approximately equal to the azimuth offset between the respective heads. For example, one head may be radially oriented and positioned at azimuth position φ1, and another head may be radially oriented and positioned at azimuth position φ2. In this example, the azimuth offset between the two heads is φ1-φ2, and the angle between the linear nozzle arrays of the two heads is also φ1-φ2.

[0073] In some embodiments, it is possible to combine two or more print heads into a single print head block. In this case, the print heads in the block are usually parallel to each other. A block containing several inkjet print heads 16a, 16b, 16c is shown in Figure 2C.

[0074] In some embodiments, the system 10 includes a stabilization structure 30 located below the head 16, with the tray 12 positioned between the tray stabilization structure 30 and the head 16. The stabilization structure 30 can function to prevent or reduce vibrations of the tray 12 that may occur when the inkjet print head 16 is operating.

[0075] The tray 12 and / or print head 16 are optionally and preferably configured to move along the vertical z-direction parallel to the vertical axis 14, thereby changing the vertical distance between the tray 12 and the print head 16. In a configuration where the vertical distance is changed by moving the tray 12 along the vertical direction, the stabilization structure 30 also preferably moves vertically with the tray 12. In a configuration where the vertical distance along the vertical direction is changed by the head 16 while the vertical position of the tray 12 remains fixed, the stabilization structure 30 is also held in a fixed vertical position.

[0076] Vertical movement can be performed by the vertical drive device 28. Once a layer is completed, the vertical distance between the tray 12 and the head 16 can be increased by a predetermined vertical interval depending on the desired thickness of the next layer to be printed (for example, by lowering the tray 12 relative to the head 16). This procedure is repeated to form a three-dimensional object layer by layer.

[0077] The operation of the inkjet print head 16, and optionally, and preferably, the operation of one or more other components of the system 10, such as the movement of the tray 12, are controlled by a computerized controller 20. The controller may have electronic circuits and a non-volatile storage medium readable by the circuits, which stores program instructions that cause the circuits to perform control operations, as further detailed below, when read by the circuits.

[0078] The controller 20 can also communicate with the host computer 24, which transmits digital data regarding manufacturing instructions based on computer object data. Digital data can be, for example, Standard Tessellation Language (STL) or Stereolithography Contour (SLC) format, Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Exchange Format (DXF), Polygon File Format (PLY), or any other format suitable for computer-aided design (CAD). The object data format is typically structured according to the Cartesian coordinate system. In such cases, the computer 24 preferably performs a procedure to convert the coordinates of each slice in the computer object data from the Cartesian coordinate system to the polar coordinate system. The computer 24 optionally, and preferably, transmits the manufacturing command in the converted coordinate system. Alternatively, the computer 24 can transmit the manufacturing command in the original coordinate system provided by the computer object data. In that case, the coordinate transformation is performed by the circuitry of the controller 20. The controller 20 can also communicate with the user interface 116, which was detailed earlier.

[0079] Coordinate transformation enables three-dimensional printing on a rotating tray. In a non-rotating system with a fixed tray, the print head typically reciprocates along a straight line on the fixed tray. In such a system, assuming a uniform ejection speed of the head, the print resolution is the same at every point on the tray. In system 10, unlike the non-rotating system, not all nozzles at the head point cover the same distance on the tray 12 in the same amount of time. The coordinate transformation is performed, optionally and preferably, so that the amount of excess material is equal at different radial positions. Representative examples of coordinate transformations according to some embodiments of the present invention are shown in Figures 3A and 3B. These represent three slices of an object (each slice corresponding to a manufacturing instruction for a different layer of the object), with Figure 3A showing the slices in Cartesian coordinates and Figure 3B showing the same slices after applying the coordinate transformation procedure to each slice.

[0080] Typically, the controller 20 controls the voltage applied to each component of the system 10 based on manufacturing instructions and instructions from the stored program described below.

[0081] Generally, the controller 20 controls the print head 16 while the tray 12 is rotating to eject droplets of construction material in layers, thereby printing a three-dimensional object on the tray 12.

[0082] System 10 optionally and preferably comprises one or more radiation sources 18. Depending on the material used for molding, these may be, for example, ultraviolet, visible light, or infrared lamps, or other electromagnetic radiation sources, or electron beam sources. The radiation sources may include, but are not limited to, any type of radiation emitter, including light-emitting diodes (LEDs), digital photoprocessing (DLP) systems, resistance heating lamps, etc. The radiation sources 18 play a role in curing or solidifying the molding material. In various exemplary embodiments of the present invention, the operation of the radiation sources 18 is controlled by a controller 20, which starts and stops the radiation sources 18 and optionally also controls the amount of radiation emitted by the radiation sources 18.

[0083] In some embodiments of the present invention, the system 10 further comprises a leveling device 32, which may optionally and preferably also comprise a roller having blades, and optionally a waste collection device (not shown, see Figure 1A), as will be detailed below. The leveling device 32 serves to straighten the newly formed layer before forming the next layer on top of it.

[0084] In some optional embodiments, the leveling device 32 has the shape of a cone roller, with its axis of symmetry 34 inclined with respect to the surface of the tray 12 and positioned so that its surface is parallel to the tray surface. This embodiment is shown in a side view of the system 10 (Figure 1C). The cone roller can have the shape of a cone or a frustocone.

[0085] The operation of the leveling device 32 is controlled by a controller 20 which can optionally and preferably start and stop the leveling device 32. In some optional embodiments, the controller 20 controls the position leveling device 32 to be aligned vertically (parallel to the axis 14) and / or radially (parallel to the tray 12 and either toward or away from the axis 14).

[0086] In some embodiments of the present invention, the print head 16 is configured to reciprocate relative to the tray along a radial direction r. These embodiments are useful when the length of the nozzle array 22 of the head 16 is shorter than the radial width of the work area 26 on the tray 12. The radial movement of the head 16 is optionally and preferably controlled by a controller 20.

[0087] Some embodiments envision the production of an object by ejecting different materials from different nozzle arrays (belonging to the same or different print heads). These embodiments, in particular, provide the function of selecting materials from a predetermined number of materials and defining a desired combination of the selected materials and their properties. According to these embodiments, the spatial locations in which each material is deposited in layers are defined by either having different materials occupy different three-dimensional spatial locations, or by placing two or more different materials in substantially the same three-dimensional location or adjacent three-dimensional locations, and then spatially mixing the materials within the layer after deposition to form a composite material at each of the single or multiple locations.

[0088] Any combination or mixture of materials after deposition is possible. For example, after a particular material is extruded, it may retain its original properties. However, if it is extruded simultaneously with another material or other extruded material at the same or nearby location, a composite material may be formed that has one or more properties different from those of the extruded materials.

[0089] In some embodiments of the present invention, the system extrudes a digital material into at least one of multiple layers.

[0090] As used herein and in the art, the term “digital material” refers to a combination of two or more materials at the pixel or voxel level such that pixels or voxels of different materials intersect with each other in a given area. Such digital materials can exhibit novel properties influenced by the choice of material types and / or the ratio and relative spatial distribution of the two or more materials.

[0091] As used herein, a “voxel” of a layer refers to the physical three-dimensional element volume within the layer, corresponding to a single pixel in the bitmap describing the layer. The dimensions of a voxel are approximately equal to the dimensions of the area formed by the construction material after it has been extruded, flattened, and solidified at the locations corresponding to individual pixels.

[0092] Thus, this embodiment enables the deposition of a wide range of material combinations and allows for the creation of objects in which different parts can be composed of combinations of multiple different materials, depending on the characteristics required to characterize each part of the object.

[0093] Further details of the principle and operation of the AM system suitable for this embodiment are described in U.S. Published Patent Application No. 20100191360, the contents of which are incorporated herein by reference.

[0094] Next, refer to Figures 4A to 4H. These are schematic diagrams illustrating in more detail a leveling device 32 according to several embodiments of the present invention. The leveling device 32 is useful for planarizing layers formed during three-dimensional printing and can therefore be incorporated into any three-dimensional printing system, preferably, but not limited to, system 10 or system 110.

[0095] Figures 4A and 4B are perspective views of the upper front (Figure 4A) and lower rear (Figure 4B) of the leveling device 32. Figures 4C to 4F are front (Figure 4C), rear (Figure 4D), top (Figure 4E), and bottom (Figure 4F) views of the leveling device 32. Figure 4G is a cross-sectional view along the cutting line AA in Figures 4C and 4D. Figure 4H is a cross-sectional view along the cutting line BB in Figures 4C and 4D.

[0096] In a preferred embodiment of the present invention, the leveling device 32 comprises a rotatable roller 420 and a motor 422 for the rotatable roller 420. In the schematic diagram of Figure 4A, the motor 422 is an electric motor configured to rotate the roller 420 by a transmission belt 424 connecting the shaft 426 of the roller 420 to the shaft 428 of the motor 422. Preferably, the roller 420 and the motor 422 are mounted in a housing 430 of the leveling device.

[0097] The leveling device 32 also includes a waste collection tank 432, a blade 434 that removes waste from the roller 420 and places it into the tank 432, and a plurality of tubular structures 450. The tank 432 is preferably elongated. The length of the tank 432 is preferably at least the length of the roller 420. The tubular structures 450 act as mechanisms for delivering construction material from the tank 432 to a waste tank or waste cartridge (not shown) by, for example, a pumping device 452. Thus, each tubular structure 450 has an inlet 454 near the base 436 of the tank 432 and an outlet 456 connectable to the pumping device 452, which is optionally and preferably controlled by a controller of the printing system (e.g., controller 20). The pumping device 452 can be implemented as a single pump having a plurality of inlet ports, for example in the form of a manifold, connected to the outlet 456 of the structure 450. Alternatively, the pumping device 452 may be implemented as a plurality of individual pumps, with two or more pumps connected to separate tubular structures 450. The operation of a pump device 452 according to several embodiments of the present invention is described below.

[0098] In the schematic diagrams shown in Figures 4A to 4H, the tank 432 is attached to the housing 430 by screws 402 (see Figure 4G). However, this is not necessarily required, as the tank 432 is usually removed periodically from the leveling device 232 for maintenance. Therefore, from the viewpoint of facilitating maintenance, some embodiments of the present invention, though not limited to these, may also be configured to connect the tank 432 to the housing 430 by a quick release mechanism such as an elastic clip connector or a magnetic connector. Preferably, the tubular structure 450 is positioned such that its inlet 454 is located inside the tank 432 without being fixed to the tank 432. The advantage of these embodiments is that the tank 432 can be easily and quickly removed from the housing 430 because it is not necessary to disconnect the outlet 456 of the tubular structure 450 from the pump device 452.

[0099] Figures 5A to 5C schematically show exemplary methods for assembling the leveling device 32 and integrating it into a three-dimensional printing system (e.g., systems 10 and 110).

[0100] Figure 5A is an exploded view of a housing 430, a tank 432, and a roller 420 according to several embodiments of the present invention, illustrating the assembly method of the leveling device 32. Preferably, the leveling device 32 is assembled so that the tank 430 is mounted on the rear side of the housing 430. The housing 430 consists of a pair of bearing holders 480 for housing the bearings 482 of the roller 420, an opening 490 for receiving the shaft 428 of the motor 422, and a slot 492 for fixing a tubular structure 450 (see Figure 5A) therein. The bearing holders 480 are preferably open on one side (the bottom side in this embodiment), in which case the bearings 482 are introduced through the open side of the holders 480. The bearings 482 can be optionally and preferably secured within the bearing holders 480 by elastic clips 484. An advantage of these embodiments is that the tilt of the shaft 426 can be easily adjusted. Thus, when installed in a printing system, it takes a horizontal orientation. Preferably, the tilt adjustment of the shaft 426 is performed before the housing 430 is installed in the printing system.

[0101] The belt wheel 488 is preferably mounted on the shaft 426 of the roller 420 to provide mechanical connection with the rotating shaft 428 of the motor 422. In the schematic diagram shown in Figure 5, the clip is connected to the housing 430 by a screw 486. However, this is not always the case, as in some embodiments the clip 484 is of the quick-release type to facilitate and quickly remove and replace or install the roller 420 for maintenance.

[0102] Figures 5B and 5C are schematic diagrams showing perspective views of the front (Figure 5B) and rear (Figure 5C) sides of the beam member 500. This can be used according to several embodiments of the present invention to mount the leveling device 32 on the tray of a three-dimensional printing system.

[0103] The waste collection tank 432 and the tubular structure 450 are clearly shown in Figures 6A to 6. The tank 432 comprises a base 436, side walls 438, and optionally, and preferably, a cover 440. The advantage of the cover 440 is that it can be configured to block irradiation from the radiation source of the apparatus 324, thereby preventing solidification of the construction material collected in the tank 432. Figures 6A to 6C show a side view (Figure 6A), a perspective view (Figure 6B), and a cross-sectional view along the cutting line AA of the tank 432 without the cover 440 in Figure 6B (Figure 6C). Figures 6D to 6F show a perspective view (Figure 6D), a cross-sectional view along the cutting line AA of the tank 432 in Figure 6D (Figure 6E), and an exploded view (Figure 6F) of the tank 432 with the cover 440, respectively. In embodiments in which the tank 432 includes the cover 440, the cover 440 is preferably provided with an opening 462 to receive the tubular structure 450.

[0104] Figures 6A-6F show a preferred configuration in which there are three tubular structures 450 along the length of the tank 432, but it should be understood that in some embodiments of the present invention, configurations with four or more or two or fewer tubular structures 450 are also conceivable. One or more tubular structures 450 may optionally and preferably have a siphon shape. The advantage of these embodiments is that such a shape prevents backflow of residual liquid from the upper portion of the tubular structure 450 into the tank 432.

[0105] Referring to the exploded view shown in Figure 6F, the blade 434 is preferably elongated in shape, having a straight blade end 464 extending along its entire length. The length of the blade 434 is at least the length of the roller 420, and optionally and preferably longer than the length of the roller 420 (e.g., about 1 to 5 mm longer). The width of the blade 434 may be about 0.02 mm to about 0.2 mm, for example, about 0.05 mm. The angle between the blade and the normal to the surface of the roller 420 is preferably about 50° to about 80°, for example, about 65°. Preferably, the front side wall 438 of the tank 432 has a pin 466, and the blade has a plurality of holes 468 configured to receive the pin 466. The advantage of such a configuration is that when the tank 432 is mounted to the housing 430, the alignment of the blade 434 is ensured. In some embodiments, the blade 434 is fixed to the front side wall 438 by an elongated blade holder 470. The blade holder 470 can be attached to the wall 438 by any mounting technique such as welding (e.g., ultrasonic welding) or adhesive bonding.

[0106] In various embodiments of the present invention, the base 436 of the tank 432 comprises a plurality of separate recessed regions 442. In these embodiments, for one or more tubular structures 450 (e.g., each tubular structure), the inlet 454 is located in one of the recessed regions 442, as shown in Figure 6E. The recessed regions 442 function as liquid recoverers, allowing liquid building material to flow into those regions 442 by gravity. The recessed regions 442 can be configured in any shape. For example, the base 436 is a non-flat surface with a wavy shape, in which case the recessed regions 442 are the valleys of that wavy shape. The wavy shape does not need to be curved. For example, in the embodiment shown in Figure 6E, the non-flat surface of the base 436 comprises a plurality of inclined portions 444 that form a wavy shape. Other shapes are also possible for the recessed regions 442. For example, the recessed regions 442 may be well-shaped with vertical walls, inclined walls, stepped walls, or curved walls.

[0107] Using tubular structures 450 at multiple different locations on the base 436 is advantageous because it allows for flexibility in how waste is discharged. If the pumping device 452 has a single pump connected to the outlets of all the tubular structures, the suction action of that single pump generates negative pressure in all the tubular structures simultaneously, thereby discharging the waste from the entire area of ​​the base 436. If the pumping device 452 has two or more separate pumps connected to separate tubular structures 450, the separate pumps can be operated collectively or, more preferably, individually. When the pumps are operated collectively, the situation is similar to when using a single pump, except that different pressure levels can be applied to different tubular structures, and negative pressure can be generated in all the tubular structures simultaneously.

[0108] When pumps are operated individually, the controller operates some pumps and stops others according to a predetermined procedure. For example, if the width of a layer formed on the working area of ​​a printing system tray (e.g., tray 12 of system 10 or tray 360 of system 110) is wider than the length of the nozzle array that extrudes the construction material, then two or more extrusion passes are required to complete the layer. Here, the nozzle array is displaced in the indexing direction with each pass. On the other hand, the roller 420 can be made sufficiently long so that its length is at least the width of the working area of ​​the tray (see, for example, working area 26 in Figure 1B). As a result, it is not necessary to move the roller in the indexing direction (r direction in Figure 1B) between extrusion passes. In this case, in each pass, there is a portion of the roller 420 that does not come into contact with the construction material. As a result, there is a portion of the base 436 that does not receive waste.

[0109] According to some embodiments of the present invention, pumps connected to the outlets of tubular structures having inlets at the base portion 436 that do not receive waste are not operated. This can be ensured by synchronizing the operation of multiple pumps of the pumping device 452 with the position of the nozzle array relative to the tray. Thus, according to some embodiments of the present invention, the controller of the printing system (e.g., controller 20) operates one or more pumps connected to tubular structures having inlets at indexing positions within the indexing direction region covered by the nozzle array. The advantages of this operating method are that energy can be saved and maintenance intervals can be extended.

[0110] Referring again to Figures 4A to 4H, in some embodiments of the present invention, the leveling device 32 includes a rotation sensor 446 that generates a signal indicating the rotation of the roller 420 (see Figures 4A and 4D). The sensor 446 is optionally and preferably mounted to the housing 430 by a bracket 448 or any other type of support structure. The signal generated by the sensor 446 is transmitted to the controller of the three-dimensional printing system (e.g., controller 20 of system 10 or system 110). In response to the signal from the sensor 446, the controller starts, stops, or otherwise modifies the operation of one or more components of the printing system. Typically, if the rotation speed of the roller 420 is zero, or not zero but below a predetermined threshold, the controller issues a warning signal, for example using the user interface 116, and optionally and preferably (e.g., by stopping all nozzles in the array and ending the relative motion between the print block and the tray) terminates the print job. A predetermined threshold can be selected based on, for example, the rotational speed of the motor 422 (e.g., the motor's rotational speed, or 90% of the motor's rotational speed).

[0111] In this embodiment, although not limited to this, a rotation sensor composed of a magnetic field sensor such as a Hall effect sensor or a giant magnetoresistance sensor is assumed. In these embodiments, a permanent magnet 427 is optionally and preferably attached to the shaft 426 of the roller 420, and the rotation sensor 446 responds to changes in the magnetic field generated from the magnet 427.

[0112] Alternatively, the rotation sensor may be an optical sensor such as an optical encoder, or an electromechanical sensor such as a conductive encoder, although this is not limited to the above.

[0113] In some embodiments of the present invention, the leveling device 32 includes a placement sensor 460 (see Figures 4A and 4C) for generating a signal indicating the mounting of the tank 432 to the housing 430. The signal generated by the sensor 460 is transmitted to a controller of the three-dimensional printing system (e.g., controller 20 of system 10 or system 110). In response to the signal from the sensor 460, the controller starts, stops, or otherwise modifies the operation of one or more components of the printing system. Typically, if the signal from the sensor 460 indicates that the tank 432 is not placed (e.g., not there or not properly mounted on the housing 430), the controller issues a warning signal, for example using the user interface 116, and optionally, and preferably (e.g., by stopping all nozzles in the array and ending the relative movement between the print block and the tray), terminates the print job.

[0114] The placement sensor 460 is preferably mounted near the compartment 432 of the housing 430, for example, in a recess 494 in the wall configured to house the placement sensor 460 (see Figure 5A), and may be any type, including but not limited to an electromechanical switch or an optical sensor.

[0115] As used herein, the term “approximately” refers to ±10%.

[0116] The term “exemplary” is used herein to mean “example, illustration, or illustrative.” Any embodiment described as “exemplary” should not necessarily be construed as being preferable or advantageous to other embodiments, and / or not preclude the incorporation of features of other embodiments.

[0117] The term “optionally” is used herein to mean “provided in one embodiment and not provided in another embodiment.” Any particular embodiment of the present invention may include several “optionally” features, provided that such features do not conflict with each other.

[0118] The terms "to prepare," "prepared," "include," "included," and "to possess," as well as their conjugations, all mean "to include, but not limited to."

[0119] The term "consisting of" means "including and limited to."

[0120] The term "essentially consisting of" means that the composition, method, or structure may include additional components, steps, and / or parts, but only if such additional components, steps, and / or parts do not substantially alter the basic and novel characteristics of the claimed composition, method, or structure.

[0121] As used herein, the singular forms “a, an” and “the” also include plural references unless the context explicitly states otherwise. For example, the terms “one compound” or “at least one compound” may include multiple compounds, including mixtures thereof.

[0122] Through this application, various embodiments of the present invention may be presented in range form. It should be understood that range form descriptions are merely for convenience and simplification and should not be interpreted as a fixed and immutable limitation of the scope of the present invention. Therefore, range descriptions should be considered to specifically disclose all possible subranges, along with the individual numerical values ​​within that range. For example, a range description such as 1-6 should be considered to have specifically disclosed subranges such as 1-3, 1-4, 1-5, 2-4, 2-6, 3-6, and individual numerical values ​​within that range, such as 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0123] Whenever a numerical range is indicated herein, it is understood to include any cited numerical value (fraction or integer) within that range. The phrases “in the range between” the first and second designations, and “from” the first designation to the second designation, are used interchangeably herein to mean the first and second designations, as well as all fractions and integers between them.

[0124] It is understood that certain features of the present invention, even if described in the context of separate embodiments for clarity, may be provided in combination in a single embodiment. Conversely, various features of the present invention described in the context of a single embodiment for brevity may be provided separately or in any suitable partial combination, or in a manner suitable for any other described embodiment of the present invention. Certain features described in the context of various embodiments should not be considered essential features of those embodiments unless the embodiment would be unable to function without those elements.

[0125] While the present invention has been described in relation to its specific embodiments, it will be obvious to those skilled in the art that many alternatives, modifications, and variations are apparent. Therefore, the spirit of the appended claims and all such alternatives, modifications, and variations within their broad scope are intended to be encompassed.

[0126] All publications, patents, and patent applications referenced herein are incorporated herein by reference in their entirety to the same extent that each individual publication, patent, and patent application is incorporated herein by reference specifically and individually. Furthermore, no citation or specification of any reference within this application should be construed as an admission that such reference is available as prior art to the present invention. Insofar as they are used as section headings, they should not necessarily be construed as restrictive. Furthermore, any priority documents of this application are incorporated herein by reference in their entirety.

Claims

1. A leveling device for a three-dimensional printing system, Rotatable rollers, A motor for rotating the roller, Waste collection tank and A blade for removing liquid waste from the roller into the waste collection tank, Multiple tubular structures, Equipped with, Each tubular structure has an inlet near the base of the waste collection tank and an outlet that can be connected to a pump device, and at least one of the tubular structures is formed as a siphon. The base is a non-flat surface having a wavy shape and is composed of a plurality of separate recessed regions, the recessed regions being valleys of the wavy shape, and the inlet of each tubular structure is located in one of the recessed regions.

2. The apparatus according to claim 1, wherein the non-flat surface comprises a plurality of inclined portions that form the wavy shape.

3. The apparatus according to claim 1 or 2, further comprising a rotation sensor for generating a signal indicating the rotation of the roller.

4. The apparatus according to claim 3, wherein the rotation sensor is equipped with a magnetic sensor.

5. The apparatus according to claim 4, wherein the magnetic sensor comprises a Hall effect sensor.

6. The apparatus according to any one of claims 1 to 5, comprising a housing connectable to the three-dimensional printing system, wherein at least one of the rollers and the waste collection tank is attached to the housing.

7. The system further comprises a placement sensor for generating a signal indicating the attachment of the waste collection tank to the housing. The apparatus according to claim 6.

8. The apparatus according to claim 7, wherein the aforementioned placement sensor is equipped with a mechanical switch.

9. The apparatus according to claim 7, wherein the aforementioned placement sensor is equipped with an optical sensor.

10. The apparatus according to any one of claims 6 to 8, wherein at least one of the roller and the waste collection tank is detachably attached to the housing by a rapid release mechanism.

11. The apparatus according to claim 10, wherein the rapid release mechanism is selected from the group consisting of elastic clip connectors and magnetic connectors.

12. A three-dimensional printing system, An array of nozzles that dispense building materials, A leveling device according to any one of claims 1 to 11, A pump device connected to the outlet of the tubular structure, A computerized controller configured to operate at least the array of nozzles, A system equipped with these features.

13. The system according to claim 12, wherein the pumping device comprises at least two separate pumps, each connected to the outlets of different tubular structures, and the computerized controller is configured to start and stop each of the pumps individually.

14. The system according to claim 13, comprising a tray for receiving building material discharged from the nozzles of the array of nozzles, wherein the width of the working area of ​​the tray is greater than the length of the array of nozzles, and the length of the roller is at least the width of the working area.

15. The system according to claim 14, wherein the computerized controller is configured to start and stop each of the pumps based on the position of the array of nozzles relative to the tray.

16. The system according to any one of claims 12 to 15, wherein the leveling device comprises a position sensor for generating a signal indicating that the waste collection tank is positioned below the roller, and the computerized controller is configured to receive the signal from the position sensor and to generate an alarm or to stop the nozzles of the nozzle array if the waste collection tank is not in the correct position.

17. The system according to any one of claims 12 to 16, wherein the leveling device comprises a rotation sensor for generating a signal indicating the rotation of the roller, and the computerized controller is configured to receive the signal from the rotation sensor and to generate an alarm or stop the nozzles of the nozzle array if the rotation speed is zero or below a predetermined threshold.

18. The leveling device comprises a housing connected to the three-dimensional printing system, and the waste collection tank is detachably attached to the housing by a rapid release mechanism, according to any one of claims 12 to 17.

19. A method for performing maintenance on the system described in any one of claims 12 to 18, The waste collection tank is removed from the housing, Perform at least one maintenance operation when the waste collection tank is removed, The waste collection tank is attached to the housing, A method that includes this.

20. A method for leveling layers of construction material during three-dimensional printing, During the relative motion between the roller and the layer, the outermost surface of the layer is engaged with the rotating roller of the leveling device according to any one of claims 1 to 11, thereby recovering excess construction material into the waste recovery tank. The pump device is operated via at least one of the tubular structures to remove at least a portion of the excess construction material from the waste collection tank, A method that includes this.

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