A device to enhance the safety of three-dimensional printing

Abstract

A safety system for a rotary tray of a three dimensional printing system is provided, the safety system comprising a latch including a locking member operable to assume a locked state in which the latch prevents closure of a door of the printing system when the locking member prevents rotation of the tray, and an unlocked state in which the latch allows closure of the door when the locking member allows rotation of the tray.

Description

[Technical Field]

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 015,699, filed April 27, 2020, the contents of which are incorporated herein by reference in their entirety.

[0002] The present invention, in some embodiments thereof, relates to three-dimensional printing, and more particularly, but not exclusively, to an apparatus for enhancing the safety of three-dimensional printing. [Background technology]

[0003] Additive manufacturing (AM) is generally a process for producing three-dimensional (3D) objects using a computer model of the object. Such processes are used in a variety of fields, including design-related areas for visualization, demonstration, and mechanical prototyping, as well as rapid manufacturing.

[0004] The basic operation of any additive manufacturing system consists of slicing a three-dimensional computer model into thin cross-sectional sections, converting the results into two-dimensional positional data, and feeding that data to a controller that fabricates the three-dimensional structure layer by layer.

[0005] Additive manufacturing involves many different approaches to manufacturing, including three-dimensional printing, such as three-dimensional inkjet printing, thin film deposition modeling, fused deposition modeling, and the like.

[0006] In a three-dimensional printing process, for example, a build material is ejected from a dispensing head having a set of nozzles to deposit layers of the build material onto a support structure. Depending on the build material, the layers may then be cured or solidified using appropriate equipment. The build material may include a modeling material that forms the object and a support material that supports the object during construction. Various three-dimensional printing techniques exist, such as those disclosed in commonly assigned U.S. Patents 6,113,999, 6,149,172, 6,153,176, 6,163,177, 6,173,178, 6,181,179, 6,192,185, 6,196,187, 6,197,196, 6,198,197, 6,19 ...

[0007] For example, U.S. Patent No. 10,611,136 discloses a three-dimensional printing system having a rotating tray configured to rotate about a vertical axis, a print head having a plurality of separated nozzles, and a controller configured to control the inkjet print head to eject droplets of build material in layers as the tray rotates. The system also includes a leveling device that levels a newly formed layer before a subsequent layer is formed thereon. Summary of the Invention

[0008] According to an aspect of some embodiments of the present invention, there is provided a safety system for a carousel tray of a three dimensional printing system comprising a print head, a controller, and a print chamber having an access opening. The safety system includes a latch having a locking member operable to assume a locked state in which the latch prevents closing of the door when the locking member prevents rotation of the tray, and an unlocked state in which the latch allows closing of the door when the locking member allows rotation of the tray. The safety system optionally and preferably includes a door status sensor configured to send a signal to the controller indicative of whether the door at the access opening is open or closed.

[0009] According to some embodiments of the present invention, the safety system includes a sprocket wheel connected to and rotating with the tray, with a locking member engaging the sprocket wheel in the locked state and disengaging from the sprocket wheel in the unlocked state.

[0010] According to some embodiments of the present invention, the latch is reciprocally slidable radially relative to the tray, and when the latch is pulled outward the latch assumes a locked state, and when the latch is pulled inward the latch assumes an unlocked state.

[0011] According to some embodiments of the present invention, the latch projects out of the access opening when pulled outward, thereby preventing the door from closing.

[0012] According to some embodiments of the present invention, a spring configured to bias the latch to maintain the latch in a locked state upon actuation of the latch is provided.

[0013] According to some embodiments of the invention, the safety system comprises a resilient lever connected to the latch such that when the lever is in a relaxed state, the lever impacts against a stop element to prevent the latch from assuming the unlocked state, and when the lever is in a tensioned state, the lever bypasses the stop element to allow the latch to assume the unlocked state.

[0014] According to some embodiments of the invention, the height of the locking member is selected to support the tray in the locked state. According to some embodiments of the invention, the height of the locking member is selected to support the tray in the locked state and not in the unlocked state.

[0015] According to some embodiments of the present invention, the latch is a push-push latch.

[0016] In accordance with an aspect of some embodiments of the present invention, there is provided a three dimensional printing system comprising a print head, a carousel, a controller, a print chamber having an access opening, and a safety system as described above and optionally and preferably in more detail below.

[0017] According to an aspect of some embodiments of the present invention, there is provided a method of printing a three-dimensional object, the method including receiving three dimensional printing data corresponding to a shape of the object, providing the data to a three dimensional printing system, operating the three dimensional printing system to print the object, opening a print chamber door, actuating a latch to lock a tray, and removing the object from the tray.

[0018] According to an aspect of some embodiments of the present invention there is provided a system for three-dimensional printing comprising: a rotating tray configured to rotate horizontally about a vertical axis, a print head configured to dispense a build material, a leveling device for leveling the build material dispensed by the print head, support rollers positioned below the tray below the leveling device for absorbing forces applied by the leveling device, and a controller configured to control the print head to print a three-dimensional object on the tray.

[0019] According to some embodiments of the present invention, a three dimensional printing system includes a latch having a locking member operable to assume a locked state in which the locking member prevents rotation of the tray and an unlocked state in which the locking member allows rotation of the tray.

[0020] According to some embodiments of the present invention, the height and shape of the locking member are selected to at least partially absorb normal forces exerted on the tray.

[0021] According to some embodiments of the present invention, the latch is a push-push latch.

[0022] According to some embodiments of the present invention, the latch comprises a lever and a stop element.

[0023] According to some embodiments of the invention, the lever comprises a metal sheet and the stop element comprises a screw head.

[0024] 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 present specification, including definitions, will control. Furthermore, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

[0025] Implementation of the method and / or apparatus of embodiments of the present invention may involve performing or completing selected tasks manually, automatically, or a combination thereof. Furthermore, depending on the actual instrumentation and installation of the method and / or apparatus embodiments of the present invention, some selected tasks may be performed by hardware, or by software or firmware using an operating system, and / or a combination thereof.

[0026] For example, hardware for performing selected tasks according to embodiments of the present invention may be implemented as a chip or circuit. With respect to software, selected tasks according to embodiments of the present invention may be implemented as a plurality of software instructions executed by a computer using any suitable operating system. In exemplary embodiments of the present invention, one or more tasks according to exemplary embodiments of the methods and / or apparatus described herein are performed by a data processor, such as a computing platform, executing a plurality of instructions. Optionally, the data processor includes volatile memory for storing instructions and / or data, and / or non-volatile storage, such as a magnetic hard disk and / or removable media, for storing instructions and / or data. Optionally, a network connection is also provided. A display and / or user input device, such as a keyboard or mouse, are also optionally provided.

[0027] Certain embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. Referring now specifically to the drawings in detail, it is emphasized that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken together with the drawings will make apparent to those skilled in the art how embodiments of the invention may be carried out. [Brief explanation of the drawings]

[0028] [Figure 1A]FIG. 1 is a schematic diagram of an additive manufacturing system, according to some embodiments of the present invention. [Figure 1B] FIG. 1 is a schematic diagram of an additive manufacturing system, according to some embodiments of the present invention. [Figure 1C] FIG. 1 is a schematic diagram of an additive manufacturing system, according to some embodiments of the present invention. [Figure 2A] FIG. 1 is a schematic diagram of a print head according to some embodiments of the present invention. [Figure 2B] FIG. 1 is a schematic diagram of a print head according to some embodiments of the present invention. [Figure 2C] FIG. 1 is a schematic diagram of a print head according to some embodiments of the present invention. [Figure 3A] FIG. 1 is a schematic diagram illustrating coordinate transformation according to some embodiments of the present invention. [Figure 3B] FIG. 1 is a schematic diagram illustrating coordinate transformation according to some embodiments of the present invention. [Figure 4A] 4A and 4B are schematic diagrams showing top (FIGS. 4A and 4B) and side (FIGS. 4C and 4D) views of a print chamber, carousel, and latch according to some embodiments of the present invention. [Figure 4B] 4A and 4B are schematic diagrams showing top (FIGS. 4A and 4B) and side (FIGS. 4C and 4D) views of a print chamber, carousel, and latch according to some embodiments of the present invention. [Figure 4C] 4A and 4B are schematic diagrams showing top (FIGS. 4A and 4B) and side (FIGS. 4C and 4D) views of a print chamber, carousel, and latch according to some embodiments of the present invention. [Figure 4D] 4A and 4B are schematic diagrams showing top (FIGS. 4A and 4B) and side (FIGS. 4C and 4D) views of a print chamber, carousel, and latch according to some embodiments of the present invention. [Figure 5A] 1 is a schematic perspective view of a latch for locking and unlocking a carousel, according to some embodiments of the present invention. [Figure 5B] 1 is a schematic perspective view of a latch for locking and unlocking a carousel, according to some embodiments of the present invention. [Figure 5C]1 is a schematic perspective view of a latch for locking and unlocking a carousel, according to some embodiments of the present invention. [Figure 6A] 6A and 6B are schematic perspective views showing the bottom (FIG. 6A) and side (FIGS. 6B, 6C) views of a latch for locking and unlocking a carousel, according to some embodiments of the present invention. [Figure 6B] 6A and 6B are schematic perspective views showing the bottom (FIG. 6A) and side (FIGS. 6B, 6C) views of a latch for locking and unlocking a carousel, according to some embodiments of the present invention. [Figure 6C] 6A and 6B are schematic perspective views showing the bottom (FIG. 6A) and side (FIGS. 6B, 6C) views of a latch for locking and unlocking a carousel, according to some embodiments of the present invention. [Figure 7] FIG. 2 is a schematic exploded view of a platter on a vertical axis, according to some embodiments of the present invention. [Figure 8A] 1 is a schematic diagram illustrating a locking member supporting a platter according to some embodiments of the present invention. [Figure 8B] 1 is a schematic diagram illustrating a locking member supporting a platter according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention, in some embodiments thereof, relates to three-dimensional printing, and more particularly, but not exclusively, to an apparatus for enhancing the safety of three-dimensional printing.

[0030] Before describing at least one embodiment of the present invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of components and / or methods set forth in the following description and / or illustrated in the drawings and / or examples. The invention is capable of other embodiments and of being practiced or carried out in various ways.

[0031] The present method and system fabricates a three-dimensional object layer-by-layer by forming multiple layers in a construction pattern that corresponds to the shape of the object based on computer object data, which may be in any known format, including but not limited to Standard Tessellation Language (STL) or Stereolithography Contour (SLC) format, Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Interchange Format (DXF), Polygon File Format (PLY), or any other format suitable for computer-aided design (CAD).

[0032] As used herein, the term "object" refers to the entire object or a portion thereof.

[0033] Each layer is formed by an additive manufacturing device that scans a two-dimensional surface to pattern it. During scanning, the device visits multiple target locations on the two-dimensional layer or surface and determines for each target location or group of target locations whether or not that target location or group of target locations should be covered with a build material formulation, and what type of build material formulation should be delivered there. The determination is made according to a computer image of the surface.

[0034] In preferred embodiments of the present invention, AM comprises three-dimensional printing, more preferably three-dimensional inkjet printing. In these embodiments, a build material formulation is dispensed from a printhead having one or more nozzle arrays to deposit the build material formulation layer by layer onto a support structure. The AM device thus dispenses the build material formulation at target locations to be covered, leaving other target locations empty. The device typically includes multiple nozzle arrays, each of which can be configured to dispense a different build material formulation. Thus, different target locations can be occupied by different build material formulations. Types of build material formulations are broadly divided into two categories: build material formulations and support material formulations. Support material formulations act as a support matrix or structure to support an object or portion of an object during the manufacturing process and / or for other purposes, for example, to provide a hollow or porous object. The support structure may also include additional build material formulation elements, for example, to provide additional support strength.

[0035] Build material formulations are generally compounds formulated for use in additive manufacturing that are capable of forming three-dimensional objects by themselves, i.e., without the need for mixing or combining with any other substances.

[0036] The final three-dimensional object may be made from a build material formulation, or a combination of build material formulations, or a build material and support material formulation, or variations thereof (e.g., after solidification, e.g., curing), all of which are well known to those skilled in the art of solid free-form molding.

[0037] In some exemplary embodiments of the invention, an object is fabricated by dispensing two or more different build material formulations, each material formulation being dispensed through a different nozzle array (on the same or different print head) of the AM device. In some embodiments, two or more such nozzle arrays dispensing different build material formulations are all located on the same print head of the AM device. In some embodiments, the nozzle arrays dispensing different build material formulations are located on separate print heads. For example, a first nozzle array dispensing a first build material formulation is located on a first print head, and a second nozzle array dispensing a second build material formulation is located on a second print head.

[0038] In some embodiments, both the nozzle array that dispenses the build material formulation and the nozzle array that dispenses the support material formulation are located on the same print head, while in some embodiments, the nozzle array that dispenses the build material formulation and the nozzle array that dispenses the support material formulation are located on separate print heads.

[0039] Another representative, non-limiting example of a system 10 suitable for AM of objects according to some embodiments of the present invention is shown in Figures 1A-1C, which show a top view (Figure 1A), a side view (Figure 1B), and an isometric view (Figure 1C) of the system 10. Preferably, the system 10 is a three-dimensional inkjet printing system.

[0040] In this embodiment, system 10 includes a tray 12 and a plurality of inkjet print heads 16, each having one or more nozzle arrays with one or more separated nozzles. Material used for three-dimensional printing is supplied to heads 16 by a build material supply system 42.

[0041] Each print head is optionally and preferably supplied via one or more build material formulation tanks, which may optionally include a temperature control unit (e.g., a temperature sensor and / or a heating device) and a material formulation level sensor.

[0042] To eject the build material formulation, a voltage signal is applied to the print head, as in piezoelectric inkjet printing technology, to selectively deposit droplets of the material formulation through the print head nozzles. The ejection speed of each head depends on the number of nozzles, the type of nozzle, and the applied voltage signal rate (frequency). Such print heads are known to those skilled in the art of solid free-form molding.

[0043] The tray 12 may be disk-shaped or may be annular, although non-circular shapes are also envisioned.

[0044] The tray 12 and head 16 are optionally and preferably mounted to allow relative rotational movement between the tray 12 and 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). Below, several embodiments of the system 10 are described with particular emphasis on configuration (i), in which the tray is a rotating tray configured to rotate relative to the head 16 about a vertical axis 14, but it should be understood that the present application also contemplates configurations (ii) and (iii) for the system 10. Any of the embodiments of the system 10 described herein can be adapted to apply to either configuration (ii) or configuration (iii), and one of ordinary skill in the art would know how to make such adjustments given the details provided herein. Additionally, while some embodiments of system 10 described below place particular emphasis on rotary AM systems, the present disclosure also contemplates embodiments in which the AM system is non-rotary and the relative motion between the head and tray is translational, e.g., along a straight line. A representative example of such an AM system suitable for some embodiments is described in U.S. Patent No. 10,611,136, the contents of which are incorporated herein by reference.

[0045] In the following description, the direction parallel to the tray 12 and outward from the axis 14 will be referred to as the radial direction r, the direction parallel to the tray 12 and perpendicular to the radial direction r will be referred to herein as the azimuthal direction φ, and the direction perpendicular to the tray 12 will be referred to herein as the vertical direction z.

[0046] As described below, rotational motion between the tray and print head of the system typically allows the head to scan azimuthally over the tray while dispensing build material. Accordingly, the azimuth direction is referred to interchangeably herein as the "scan direction." Typically, the print head has an array of nozzles at an angle (typically perpendicular) to the scan direction. A particular print head can thus dispense several rows of build material, each extending in the scan direction. Accordingly, the radial direction is referred to interchangeably herein as the "index direction," indicating that the rows are indexed in this direction.

[0047] It is understood that when an AM system is non-rotating, there are no radial or azimuthal directions. However, even in a non-rotating system, a print head with an array of nozzles can scan across a tray to form a row of build material. Therefore, similar terminology is used for non-rotating systems, with the direction in which the head scans across the tray being referred to as the "scan direction" and the horizontal direction perpendicular to the scan direction being referred to as the "index direction." The literature often refers to the scan direction as the X direction and the index direction as the Y direction.

[0048] As used herein, the term "radial position" refers to a position on or above tray 12 that is a particular distance from axis 14. When the term is used in reference to a print head, the term refers to a position of the head that is a particular distance from axis 14. When the term is used in reference to a point on tray 12, the term corresponds to any point belonging to a locus of points that is a circle whose radius is a particular distance from axis 14 and whose center is on axis 14.

[0049] As used herein, the term "azimuthal position" refers to a position on or above tray 12 that is at a particular azimuthal angle relative to a given reference point. A radial position, therefore, refers to any point belonging to a linear locus of points that is at a particular azimuthal angle relative to a reference point.

[0050] As used herein, the term "vertical position" refers to a position on a plane that intersects the vertical axis 14 at a particular point.

[0051] Tray 12 serves as a build platform for three-dimensional printing. The work area, on which one or more objects are printed, is typically, but not necessarily, smaller than the total area of ​​tray 12. In some embodiments of the present invention, the work area is annular. The work area is indicated by the reference numeral 26. In some embodiments of the present invention, tray 12 rotates continuously in the same direction during the formation of an object; in some embodiments of the present invention, the tray reverses its direction of rotation (e.g., oscillates) at least once during the formation of an object. Tray 12 is optionally and preferably removable. Removal of tray 12 can be performed 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), with two or more trays selected for different types of objects (e.g., different weights), different modes of operation (e.g., different rotational speeds), etc. Tray 12 replacement can be manual or automatic, as desired. When automatic exchange is used, system 10 includes a tray exchanger 36 configured to remove tray 12 from a position beneath head 16 and replace it with a replacement tray (not shown). In the representative view of Figure 1A, tray exchanger 36 is shown as a drive unit 38 having a movable arm 40 configured to pull tray 12, although other types of tray exchangers are contemplated.

[0052] Exemplary embodiments of print head 16 are shown in Figures 2A-2C. These embodiments can be used with any of the AM systems described above, including but not limited to rotating system 10 and non-rotating systems.

[0053] 2A-2B show print heads 16 having one (FIG. 2A) and two (FIG. 2B) nozzle arrays 22. The nozzles in the arrays are preferably arranged linearly along a straight line. In embodiments where a particular print head has two or more linear nozzle arrays, the nozzle arrays may optionally and preferably be parallel to one another. When a print head has two or more nozzle arrays (e.g., FIG. 2B), all arrays on that head may be supplied with the same build material formulation, or at least two arrays on the same head may be supplied with different build material formulations.

[0054] When a non-rotating system with multiple print heads is used, all print heads are optionally and preferably oriented along an index direction and their positions along the scan direction are offset relative to one another.

[0055] 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 are azimuthal offset from one another. Thus, in these embodiments, the nozzle arrays of different print heads are not parallel to one another, but rather are at an angle to one another, the angle being approximately equal to the azimuthal offset between the respective heads. For example, one head can be oriented radially and positioned at an azimuthal position φ1, and another head can be oriented radially and positioned at an azimuthal position φ2. In this example, the azimuthal offset between the two heads is φ1-φ2, and the angle between the linear nozzle arrays of the two heads is also φ1-φ2.

[0056] In some embodiments, two or more printheads can be combined into a printhead block, where the printheads in the block are generally parallel to one another. A block containing several inkjet printheads 16a, 16b, 16c is shown in Figure 2C.

[0057] In some embodiments, system 10 includes a stabilizing structure 30 positioned below head 16, with tray 12 between tray stabilizing structure 30 and head 16. Stabilizing structure 30 can function to prevent or reduce vibrations of tray 12 that may occur when inkjet print head 16 is operated. In configurations in which print head 16 rotates about axis 14, stabilizing structure 30 preferably also rotates so that stabilizing structure 30 is always directly below head 16 (with tray 12 between head 16 and tray 12).

[0058] Tray 12 and / or print head 16 are optionally and preferably configured to move parallel to vertical axis 14 along vertical direction z, allowing the vertical distance between tray 12 and print head 16 to be changed. In configurations in which the vertical distance is changed by moving tray 12 along the vertical direction, stabilizing structure 30 also preferably moves vertically with tray 12. In configurations in which the vertical position of tray 12 remains fixed and the vertical distance along the vertical direction is changed by head 16, stabilizing structure 30 is also held in a fixed vertical position.

[0059] Vertical movement can be achieved by vertical drive 28. Once a layer is completed, the vertical distance between tray 12 and head 16 can be increased (e.g., tray 12 can be lowered relative to head 16) by a predetermined vertical distance depending on the desired thickness of the next layer to be printed. This procedure is repeated to build the three-dimensional object layer by layer.

[0060] The operation of inkjet print head 16, and optionally and preferably the operation of one or more other components of system 10, such as movement of tray 12, is controlled by a controller 20. The controller may include electronic circuitry and a non-volatile storage medium readable by the circuitry that stores program instructions that, when read by the circuitry, cause the circuitry to perform control operations as described in further detail below.

[0061] The controller 20 can also communicate with a host computer 24 that transmits digital data regarding fabrication instructions based on the computer object data. The digital data may 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 organized according to a Cartesian coordinate system. In such cases, computer 24 preferably performs a procedure for converting the coordinates of each slice in the computer object data from the Cartesian coordinate system to a polar coordinate system. Computer 24 optionally and preferably transmits fabrication instructions in the transformed coordinate system. Alternatively, computer 24 can transmit fabrication instructions in the original coordinate system provided by the computer object data. In that case, the coordinate conversion is performed by circuitry in controller 20.

[0062] Coordinate transformation enables three-dimensional printing on a rotating tray. In non-rotating systems with a fixed tray, the print head typically moves back and forth along a straight line above the fixed tray. In such systems, if the head's ejection speed is uniform, the print resolution is the same at any point on the tray. Unlike non-rotating systems, in system 10, not all nozzles at the head point cover the same distance on tray 12 in the same amount of time. Coordinate transformation is optionally and preferably performed to ensure equal amounts of excess material mix at different radial locations. A representative example of coordinate transformation according to some embodiments of the present invention is shown in Figures 3A-3B, which represent three slices of an object (each slice corresponding to a fabrication command for a different layer of the object), where Figure 3A shows the slice in a Cartesian coordinate system and Figure 3B shows the same slice after applying the coordinate transformation procedure to each slice.

[0063] Generally, controller 20 controls the voltages applied to each component of system 10 based on manufacturing instructions and based on stored program instructions described below.

[0064] Generally, controller 20 controls print head 16 to eject droplets of build material formulation in layers to print a three-dimensional object onto tray 12 while tray 12 rotates.

[0065] Inkjet printheads dispense layers of build material using inkjet technology. Each printhead can be configured to dispense a different build material. If a particular printhead includes more than one nozzle array, each nozzle array can be configured to dispense a different build material. Thus, different target locations can be populated with different build materials.

[0066] The type of material delivered to each nozzle array of each print head for ejection is optionally and preferably controlled by controller 20. For example, controller 20 can signal build material supply system 42 to supply a first build material to one nozzle array of a first head and a support material to another nozzle array of the first head. Controller 20 can also signal system 42 to supply the first build material to one nozzle array of the first head, the support material to another nozzle array of the first head, and the second build material to one nozzle array of a second head. Alternatively, controller 20 can signal system 42 to supply the support material to a nozzle array of another head. The controller 20 can also send signals to the system 42 to supply a first build material to one nozzle array of the first head, a support material to another nozzle array of the first head, a second build material to one nozzle array of the second head, a third build material to another nozzle array of the second head, and so on.

[0067] System 10 optionally and preferably includes a solidification device 18 for solidifying (e.g., curing) the build material formulation. Solidification device 18 includes one or more radiation sources 18, which may be, for example, ultraviolet, visible, or infrared lamps, or other electromagnetic radiation sources, or electron beam sources, depending on the build material formulation used. Radiation sources may include any type of radiation-emitting device, including, but not limited to, light-emitting diodes (LEDs), digital light processing (DLP) systems, resistive heat lamps, etc. In various exemplary embodiments of the invention, operation of solidification device 18 is controlled by a controller 20, which can start and stop solidification device 18. If the solidification device includes a radiation source, controller 20 optionally also controls the amount of radiation produced by the radiation source.

[0068] In some embodiments of the present invention, the radiation source 18 is configured to reciprocate relative to the tray along a radial direction r. These embodiments are useful when the length of the radiation source 18 is shorter than the radial width of the working area 26 on the tray 12. The movement of the radiation source 18 in the radial direction is optionally and preferably controlled by the controller 20. Accordingly, in this embodiment, it is envisioned that the radiation source and the print head are each independently controllable and move radially along separate motion stages. This differs from conventional three-dimensional printing systems in which the print head and the radiation source are attached to the same print block and therefore move simultaneously. In some embodiments of the present invention, the controller 20 is configured to move the radiation source 18 and the head 16 asynchronously in the radial direction during operation of the system 10. In some embodiments of the present invention, the controller 20 is configured to move the radiation source 18 and the head 16 asynchronously and independently in the radial direction during operation of the system 10. These embodiments are particularly useful when it is desired to select the start time of solidification (e.g., hardening), for example, to delay solidification.

[0069] In some embodiments of the present invention, system 10 further comprises one or more leveling devices 32, which may be manufactured as rollers or blades. Leveling devices 32 serve to straighten a newly formed layer before forming the next layer thereon. In some embodiments, leveling devices 32 have the shape of a conical roller, positioned so that its axis of symmetry 34 is inclined relative to the surface of tray 12 and its surface is parallel to the surface of the tray. This embodiment is shown in a side view of system 10 (FIG. 1B). The conical roller may have the shape of a cone or a truncated cone.

[0070] The operation of leveling device 32 is optionally and preferably controlled by controller 20. The controller may start and stop leveling device 32 and optionally also control its position along the vertical direction (parallel to axis 14) and / or radial direction (parallel to tray 12, toward or away from axis 14).

[0071] The print head 6, the solidification device 18, and optionally and preferably also the leveling device 32, comprise a printing block of the system 10 and are typically mounted on a structure such as a frame 128.

[0072] In some embodiments of the invention, print head 16 is configured to move reciprocally relative to the tray along a radial direction r. These embodiments are useful when the length of nozzle array 22 of head 16 is less than the radial width of working area 26 on tray 12. Movement of head 16 in the radial direction is optionally and preferably controlled by controller 20.

[0073] Some embodiments contemplate creating an object by ejecting different material formulations from different nozzle arrays (belonging to the same or different printheads). These embodiments provide, among other things, the ability to select material formulations from a predetermined number of material formulations and define the desired combination of selected material formulations and their properties. According to these embodiments, the spatial locations at which each material formulation is deposited in a layer are defined either by having different material formulations occupy different three-dimensional spatial locations, or by placing two or more different material formulations at substantially the same three-dimensional location or adjacent three-dimensional locations and spatially mixing the material formulations within the layer after deposition, thereby forming a composite material formulation at each single or multiple locations.

[0074] Any combination or blend of subsequently deposited build material formulations is contemplated. For example, after a particular material formulation is dispensed, it may maintain its original properties. However, if it is dispensed simultaneously with another build material formulation or other dispensed material formulations at the same or nearby locations, a composite material formulation may be formed that has one or more properties different from the dispensed material formulation.

[0075] In some embodiments of the present invention, the system dispenses digital material for at least one of the layers.

[0076] As used herein and in the art, the term "digital material" refers to the combination of two or more materials at the pixel or voxel level, such that pixels or voxels of different materials intersect with one another in a region. Such digital materials can exhibit novel properties that are influenced by the choice of material type and / or the ratio and relative spatial distribution of two or more materials.

[0077] As used herein, a "voxel" of a layer refers to a physical three-dimensional elemental volume within the layer and corresponds to a single pixel in a bitmap describing the layer. The dimensions of a voxel are approximately equal to the dimensions of the area formed by the build material after it has been dispensed, flattened, and solidified at the location corresponding to the individual pixel.

[0078] This embodiment thus allows for the deposition of a wide range of material formulation combinations and enables the creation of objects where different portions may be composed of multiple different material formulation combinations depending on the properties required to characterize each portion of the object.

[0079] It is anticipated that many related AM systems will be developed during the life of this application and the maturing patent, and the scope of the term AM system is intended to include such new technologies a priori.

[0080] After the printing process is complete, the printed object is removed from the tray. Because the bottom layer of the object is typically attached to the tray, removing the printed object typically involves the use of a scraper or similar tool. In three-dimensional printing systems with rotating trays (e.g., system 10), the scraping action causes the tray to move, making it difficult to remove the object while the tray is free to rotate. Therefore, it is desirable to have a locking mechanism to prevent the tray from moving during object removal. It is also desirable to have a locking mechanism to prevent the tray from moving during maintenance of other components of the system.

[0081] The inventors have found that while locking mechanisms are advantageous for the reasons described above, their use is prone to human error (e.g., forgetting to unlock the tray before starting a new print job) that should be avoided. Accordingly, the inventors have devised a security system for a carousel of a three dimensional printing system, such as, but not limited to, carousel 12 of system 10.

[0082] 4A and 4B are schematic diagrams showing the top view of a print chamber 400 having an access opening 402 and a door 404 for the access opening 402. The print chamber 400 is dimensionally designed to accommodate the carousel 12 and, optionally and preferably, other components of the printing system, such as the print block and frame 128 (not shown in FIGS. 4A and 4B; see FIG. 1C), as described in detail above. The door 404 is preferably a rotating door, as shown in FIGS. 4A and 4B, although in some embodiments of the present invention, the door may be a sliding door. A safety system 410 is incorporated into the chamber 400. The safety system 410 includes a door status sensor 412 that indicates whether the door 404 is open or closed, and a latch 414 that is configured to assume a locked state (FIG. 4B) that prevents the door 404 from closing and the tray 12 from rotating, and an unlocked state (FIG. 4A) that allows the door 404 to close and the tray to rotate. Side views of the print chamber 400 with the door 404 closed and open are shown in Figures 4C and 4D, respectively.

[0083] The latch 414 is preferably a manually operated latch. In a preferred configuration shown in FIGS. 4A and 4B, the latch 414 slides back and forth radially relative to the tray 12. When the latch 414 is retracted inward, the latch 414 assumes an unlocked state, and when the latch 414 is pulled outward, the latch 414 assumes a locked state. For example, as shown in FIG. 4B, when the latch 414 is pulled outward, it can protrude outside the access opening 402, thereby preventing the door 404 from closing. In other embodiments, the latch 414 can be configured to pivot rather than slide radially. The latch 414 can also be configured to indirectly prevent the door from closing by activating a mechanism (not shown) that locks the door hinges.

[0084] The door status sensor 412 can be of any type, including, but not limited to, a magnetic sensor, an optical sensor, or an electromechanical switch. The signal generated by the sensor 412 is preferably transmitted to a printing system controller (not shown, see, for example, controller 20 in FIG. 1A ). In response to this signal, the controller activates or deactivates various components of the three-dimensional printing system. For example, if the signal from the sensor 412 indicates that the door is open, the controller can stop all printing operations, including deactivating the nozzle array 16, the leveling device 32, and the solidification device 18.

[0085] Thus, the combined action of sensor 412 and latch 414 of safety system 410 provides an additional measure of safety for printing system 10, as latch 414 holds door 404 open when tray 12 is locked, ensuring that the signal generated by sensor 412 when the door is open will not cause the controller to resume or start a print job.

[0086] 5A-5C are schematic perspective views of latch 414, showing the unlocked state (FIGS. 5A, 5C) and the locked state (FIG. 5B), according to some embodiments of the present invention. FIGS. 5A and 5B also show a platter 452 supporting a tray 12 (not shown), along with a nut 406 securing the center of the platter 452 to the rotation axis 14. FIG. 5C shows a perspective view of a platform 450 supporting the platter 452 and having a drive board 451 supporting the latch 414. The platform 450 rotates the platter 452, which in turn rotates the tray 12 mounted thereon, and is also configured for vertical movement, as described in detail above.

[0087] The latch 414 includes two or more sliding slots 422 that slide over respective fixed pins 424 to facilitate reciprocating movement of the latch 414 along the radial direction. The pins 424 can be fixed, for example, to a drive board 451 (see FIG. 5C) of the platform 450. The latch 414 optionally and preferably includes a locking member 416 that can engage and disengage with the platter 452. The locking member has a post shape and can be embodied, for example, as a pin or a screw. In the unlocked state (FIG. 5A), the locking member 416 disengages from the platter 452, thereby allowing the platter 452 and tray 12 to rotate. In the locked state (FIG. 5B), the locking member 416 engages with the platter 452 in a manner that prevents the platter 452 and tray 12 from rotating. A sprocket wheel 418 is preferably connected to the tray and rotates therewith. In these embodiments, the locking member 416 engages the sprocket wheel 418 in the locked state and disengages from the sprocket wheel 416 in the unlocked state.

[0088] The platform 450 preferably includes one or more support rollers 454 for supporting the tray 12 during rotation. The inventors have found it advantageous to have at least one support roller 454 below the tray and below the leveling device (not shown in FIGS. 1A-1C) to absorb forces applied by the leveling device. The additional support roller 454 is optionally and preferably attached to the latch 414.

[0089] In some embodiments of the present invention, the safety system 410 includes one or more springs 420 that bias the latch 414 to maintain the locked state when the latch 414 is activated. Preferably, the latch 414 is a push-push latch, such that when the latch 414 is in the unlocked state, moving the latch 414 slightly inward (pushing it further) releases the spring 420, thereby moving the latch 414 outward, eliminating the need for manual application of an outward force. To return the latch 414 from its locked state to its unlocked state, a force opposing the spring 420 is applied to the latch 414 over the entire length of movement of the latch 414 from the extended position to the retracted position.

[0090] The advantage of using spring 420 to bias latch 414 and maintain the locked state when latch 414 is activated is that the outward force of spring 420 prevents door 404 from closing, indirectly preventing a print job from starting or resuming when the tray is locked. Testing conducted by the inventors has revealed that, unexpectedly, during some operations, application of a strong force to the door can cause the tray to remain locked even after the door is closed. In such a situation, a controller receiving a signal indicating the door is closed may start or resume a print job before the tray has rotated. Even if the controller receives an indication that the tray has not rotated (e.g., from another sensor in the printing system), the controller may generate a warning message and request the user to perform safe maintenance. This situation should be avoided.

[0091] To overcome this problem, the inventors have devised a double lock safety principle that prevents the door from being closed when the latch 414 is in its extended position. The double lock safety principle will now be described with reference to Figures 6A-6C.

[0092] 6A-6C are bottom perspective views (FIG. 6A) and side schematic views (FIGS. 6B, 6C) of latch 414, according to some embodiments of the present invention. Shown are latch 414 in an extended position (FIGS. 6A, 6B) and a retracted position (FIG. 6C).

[0093] In the illustrated embodiment, a resilient lever 430 is connected to the latch 414 (at its bottom side in this example). The lever 430 can be embodied as a plate material, for example, but not limited to, a metal plate. A stop element 432, such as a screw, can be attached, for example, on the drive board 451 ( FIG. 5C ) of the platform 450, at a fixed radial distance from the vertical axis 14. In some embodiments of the invention, the stop element 432 passes through the sliding slot 422 or one or more additional sliding slots 434 formed in the latch 414. Thus, the stop element 430 remains fixed when the latch 414 slides. When the lever 430 is in a relaxed state ( FIGS. 6A and 6B ), an inward force on the latch 414 results in a collision between the lever 430 and the stop element 432, preventing the latch 414 from retracting and assuming its unlocked state. FIG. 6C shows the lever 430 in a tensioned state after an upward force 436 is applied to its distal end. In this state, lever 430 bypasses stop element 432, allowing latch 414 to retract and assume the unlocked state.

[0094] 7 is a schematic exploded view of a platter 452 on a vertical shaft 14, according to some embodiments of the present invention. The shaft 14 is optionally and preferably formed with a central shoulder 440 that supports the platter 452. Typically, the platter 452 is secured to the shoulder 440 by a horseshoe spring 442. The inventors have discovered that stresses on the platter 452 when removing a printed object from the platter 452 cause the horseshoe spring 442 to flex. The inventors have unexpectedly discovered that this occasional flexing can eventually become permanent, and that such permanent flexing can affect the center of rotation and / or flatness of the tray, thereby reducing print quality.

[0095] The inventors have found that the latch 414 can also be used to reduce stress on the horseshoe spring 442, thereby improving print quality of the system 10. This embodiment is shown schematically in FIGS. 8A and 8B, which show the latch 414 in an unlocked state (FIG. 8A) and a locked state (FIG. 8B). In these embodiments, the locking member 416 is provided with an enlarged head 447, such as a screw head, and the height 446 of the locking member 416 and its head 447 is selected to support the platter 452 in the locked state. This reduces stress on the axle 14 and, consequently, the horseshoe spring 442 when the platter 452 is locked, because the normal force applied by a user, for example when removing an object from the tray, is distributed between the horseshoe spring 442 and the locking member 416. The inventors have found that this significantly increases the life of the spring 442. Preferably, the height 446 of the locking member is selected to support the platter 452 in the locked state but not in the unlocked state. This can be achieved, for example, by providing a platter with a non-flat profile on its bottom side. Specifically, in these embodiments, platter 452 has a greater thickness at its periphery than at or near its center, such that when latch 414 is extended, locking member 416 bears against the thicker periphery of platter 452, and when latch 414 is retracted, there is an air gap between head 447 and the thinner non-peripheral portion of platter 452.

[0096] As used herein, the terms "about" or "approximately" refer to ±10%.

[0097] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features of other embodiments.

[0098] The term "optionally" is used herein to mean "provided in some embodiments and not provided in other embodiments." Any particular embodiment of the present invention may include multiple "optional" features unless such features are contradictory.

[0099] The terms "comprises," "comprising," "includes," "including," "having," and their conjugations mean "including but not limited to."

[0100] The term "consisting of" means "including and limited to."

[0101] The term "consisting essentially of" means that a composition, method, or structure may include additional ingredients, steps, and / or components, but only if the additional ingredients, steps, and / or components do not materially alter the basic and novel characteristics of the claimed composition, method, or structure.

[0102] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" can encompass multiple compounds, including mixtures thereof.

[0103] Throughout this application, various embodiments of the present invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as a fixed limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all possible subranges along with individual numerical values ​​within that range. For example, a description of a range such as 1 to 6 should be considered to have specifically disclosed subranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., as well as individual numerical values ​​within that range, e.g., 1, 2, 3, 4, 5, and 6. This applies regardless of the broadness of the range.

[0104] Whenever a range of numerical values ​​is given herein, it is meant to include any recited number (fractional or integer) within the stated range. The phrases "ranging between" a first specified number and a second specified number and "ranging from" a first specified number "to" a second specified number are used interchangeably herein and are meant to include the first specified number and the second specified number, and all fractional and integer numbers therebetween.

[0105] It is understood that certain features of the invention, which are for clarity described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention that are for brevity described in the context of a single embodiment may also be provided separately or in any suitable subcombination, or as appropriate to any other described embodiment of the invention. Certain features described in the context of various embodiments should not be considered essential features of those embodiments, unless the embodiment is inoperable without those elements.

[0106] While the present invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims.

[0107] All publications, patents, and patent applications mentioned in this specification are incorporated herein by reference in their entirety to the same extent as if each individual publication, patent, and patent application was specifically and individually indicated to be incorporated herein by reference. Furthermore, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent used as section headings, they shall not necessarily be construed as limiting. Additionally, any priority documents of this application are incorporated herein by reference in their entirety.

Claims

1. 1. A safety system for a carousel of a three dimensional printing system having a print head, a controller, and a print chamber having an access opening, comprising: a door status sensor configured to send a signal to the controller indicating whether a door at the access opening is open or closed; a latch including a locking member operable to assume a locked state in which the latch prevents closing of the door when the locking member prevents rotation of the tray, and an unlocked state in which the latch allows closing of the door when the locking member allows rotation of the tray; A safety system comprising:

2. 2. The safety system of claim 1, further comprising a sprocket wheel connected to the tray for rotation therewith, the locking member engaging the sprocket wheel in the locked state and disengaging from the sprocket wheel in the unlocked state.

3. 3. The safety system of claim 1, wherein the latch is reciprocally slidable inward and outward relative to the tray, and when the latch is pulled outward, the latch assumes the locked state, and when the latch is pulled inward, the latch assumes the unlocked state.

4. 4. The safety system of claim 3, wherein the latch projects out of the access opening when pulled outward to prevent the door from closing.

5. The safety system of any one of claims 1 to 4, further comprising a spring configured to bias the latch to maintain the locked state upon actuation of the latch.

6. The locking mechanism further includes a resilient lever connected to the latch, and when the lever is in a relaxed state, the lever strikes a stopper element to prevent the latch from assuming the unlocked state.

6. A safety system according to claim 1, wherein when the lever is in a tensioned state, the lever bypasses the stop element to cause the latch to assume the unlocked state.

7. A safety system according to any preceding claim, wherein the height of the locking member is selected to support the tray in the locked state of the latch.

8. 7. The safety system of claim 1, wherein the rotating tray is carried by a platter, and the height of the locking member is selected so that the locking member supports the platter in the locked state and does not support the platter in the unlocked state.

9. A safety system according to any preceding claim, wherein the latch is a push-push latch.

10. A print head; A rotating tray and A controller; a print chamber having an access opening; A safety system according to any one of claims 1 to 9; A three-dimensional printing system comprising:

11. 1. A method for printing a three-dimensional object, comprising: a computer supplies three-dimensional printing data corresponding to the shape of an object to the three-dimensional printing system of claim 10; operating a controller of the three dimensional printing system to print the object based on the three dimensional printing data; Opening the door of the print chamber; activating the latch to lock the tray; removing the object from the tray; The method includes:

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