Patent Description:
Additive manufacturing systems may be utilized to "build" an object from build material, such as organic or inorganic powders in a layer-wise manner. Conventional additive manufacturing systems include various "recoat" apparatuses that are configured to sequentially distribute layers of build material. Conventional additive manufacturing systems may further include various "print" apparatuses that are configured to deposit binder on the build material and that can be cured to the build material to "build" an object. In some configurations, build material may be fused to "build" the object via the application of energy by a laser or the like.

Document <CIT> discloses an additive manufacturing device including an air mover, such as a fan system, to invoke a gas flow across a surface of build material in a bed during the application of heat to the build material. The gas flow provides predetermined convection conditions across the surface of the build material in the bed and controls a temperature condition across the surface of the build material in the bed.

Document <CIT> discloses methods and systems for selective sintering in 3D fabrication, wherein sintering includes heating at select locations using a hot air heat element.

In some configurations, the application of new layers of build material can apply stresses on the underlying layer of cured build material, which can lead to tearing or damage of the cured build material. Further, voids can be formed in the new layer of build material, which can subsequently lead to defects in the finished object.

To reduce stresses applied to the underlying layer of cured build material and reduce voids, excess build material can initially be applied to the new layer. The excess build material can then be removed, thereby reducing the new layer of build material to a desired thickness. In some conventional configurations, the excess build material may be deposited into a drain or the like for reclamation or disposal.

However, reclamation may be time consuming and costly, and disposal of the excess build material may generally increase manufacturing costs. Embodiments of the present disclosure are directed to recoat assemblies that return excess build material to a build supply, such that the excess build material can be utilized to apply a subsequent layer of new build material. By re-using the excess build material, overall build material usage may be reduced, thereby reducing manufacturing costs.

In some configurations, the build material and/or the binder may be heated by an energy source to warm the build material and/or cure the binder. The energy sources can be attached to the recoat assembly and/or the print assembly, and the energy sources may heat the build material and/or the binder as the print assembly and/or the recoat assembly pass over the build material and/or binder. Because the energy sources move over the build material and/or binder along with the recoat assembly and/or the print assembly, the energy sources may be positioned over a particular portion of the build material and/or binder for a short period of time. Short residence time of the energy sources over particular potions of the build material and/or binder may lead to insufficient energy being applied to the build material and/or the binder. The energy sources can be positioned over particular portions of the build material and/or binder for longer times by slowing the movement of the recoat assembly and/or the print assembly. However, slowing movement of the recoat assembly and/or the print assembly may increase the time to build an object, thereby decreasing productivity and increasing manufacturing costs. In some configurations, the amount of thermal energy emitted by the energy sources can be increased, thereby increasing the amount of energy applied to the build material and/or the binder. However, increased thermal energy can cause build material and/or binder to burn or overheat, which can lead to defects in the object being produced. Accordingly, a need exists for improved systems and methods for applying thermal energy to build material and/or binder in an additive manufacturing system.

According to claim <NUM>, there is provided a method for forming an object includes moving a recoat assembly in a coating direction over a supply receptacle including build material, where the recoat assembly includes a powder spreading member, contacting the build material in the supply receptacle with the powder spreading member, irradiating, with an energy source coupled to the recoat assembly, an initial layer of build material positioned in a build receptacle, and passing a gas over the energy source, thereby heating the initial layer of build material positioned in the build receptacle via forced convection.

According to claim <NUM>, there is provided an additive manufacturing system includes at least one of a print assembly and a recoat assembly, a housing assembly coupled to the at least one of the print assembly and the recoat assembly, the housing assembly including an energy source enclosure an energy source, for irradiating an initial layer of build material positioned in a build receptacle, positioned at least partially within the energy source enclosure, and an air distribution system in communication with the energy source enclosure, wherein the air distribution system comprises a pump structurally configured to pass a gas over the energy source to heat the initial layer of build material positioned in the build receptacle via forced convection.

Additional features and advantages of the additive manufacturing apparatuses described herein, and the components thereof, will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

Reference will now be made in detail to embodiments of additive manufacturing apparatuses, and components thereof, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. Additive manufacturing systems according to the present disclosure include a recoat assembly for spreading build material in a build area. The recoat assembly may move build material from a build supply to the build area in sequential layers. In embodiments, the recoat assembly may move the excess build material back to the build supply such that the excess build material may be utilized in subsequent layers. The recoat assembly or a print assembly includes one or more energy sources that can apply energy to the build material. According to the claimed invention, an air distribution system distributes heat generated by the one or more energy sources by forced convection. These and other embodiments of recoat assemblies and print assemblies for additive manufacturing systems, additive manufacturing systems comprising the recoat and print assemblies, and methods for using the same are described in further detail herein with specific reference to the appended drawings.

Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment.

Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and are not intended to imply absolute orientation unless otherwise expressly stated.

The phrase "communicatively coupled" is used herein to describe the interconnectivity of various components and means that the components are connected either through wires, optical fibers, or wirelessly such that electrical, optical, and/or electromagnetic signals may be exchanged between the components.

Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

As used herein, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components, unless the context clearly indicates otherwise.

Referring now to <FIG>, an additive manufacturing system <NUM> is schematically depicted. The additive manufacturing system <NUM> includes a supply platform <NUM>, a build platform <NUM>, a print assembly <NUM>, a cleaning station <NUM>, and a recoat assembly <NUM>. The supply platform <NUM> is coupled to a supply platform actuator <NUM>. The supply platform actuator <NUM> is movable in the vertical direction (i.e., the +/- Z direction of the coordinate axes depicted in the figure) such that the supply platform <NUM> may be raised or lowered within a supply receptacle <NUM>. The build platform <NUM> is located adjacent to the supply platform <NUM> and, like the supply platform <NUM>, is coupled to a build platform actuator <NUM>. The build platform actuator <NUM> is movable in the vertical direction such that the build platform <NUM> may be raised or lowered (i.e., the +/- Z direction of the coordinate axes depicted in the figure) within a build receptacle <NUM>.

In operation, build material <NUM>, such as organic or inorganic powder, is positioned on the supply platform <NUM>. The supply platform <NUM> is actuated to present a layer of the build material <NUM> in the path of the recoat assembly <NUM>. The recoat assembly <NUM> is then actuated along a working axis <NUM> of the additive manufacturing system <NUM> towards the build platform <NUM>. As the recoat assembly <NUM> traverses the working axis <NUM> over the supply platform <NUM> towards the build platform <NUM>, the recoat assembly <NUM> distributes the layer of build material <NUM> in the path of the recoat assembly <NUM> from the supply platform <NUM> to the build platform <NUM>.

Thereafter, the print assembly <NUM> moves along the working axis <NUM> over the build platform <NUM> and may deposit a layer of binder <NUM> in a predetermined pattern on the layer of build material <NUM> that has been distributed on the build platform <NUM>. After the binder <NUM> is deposited, an energy source may be utilized to cure the deposited binder <NUM>, as described in greater detail herein. The print assembly <NUM> can then move to a home position <NUM> where at least a portion of the print assembly <NUM> is positioned over the cleaning station <NUM>. While the print assembly <NUM> is in the home position <NUM>, the print assembly <NUM> works in conjunction with the cleaning station <NUM> to provide cleaning and maintenance operations on the elements of the print assembly <NUM> to ensure the elements are not fouled or otherwise clogged. This may assist in ensuring that the print assembly <NUM> is capable of depositing the binder <NUM> in the desired pattern during a subsequent deposition pass.

During this maintenance interval, the supply platform <NUM> is actuated in an upward vertical direction (i.e., in the +Z direction of the coordinate axes depicted in the figure) as indicated by arrow <NUM> to present a new layer of build material <NUM> in the path of the recoat assembly <NUM>. The build platform <NUM> is actuated in the downward vertical direction (i.e., in the -Z direction of the coordinate axes depicted in the figure) as indicated by arrow <NUM> to prepare the build platform <NUM> to receive a new layer of build material <NUM> from the supply platform <NUM>. The recoat assembly <NUM> is then actuated along the working axis <NUM> of the additive manufacturing system <NUM> again to add another layer of build material <NUM> and binder <NUM> to the build platform <NUM>. This sequence of steps is repeated multiple times to build an object on the build platform <NUM> in a layer-wise manner.

While the embodiment depicted in <FIG> and described above describes the recoat assembly <NUM> and the print assembly <NUM> as being different components, it should be understood that recoat assembly <NUM> and the print assembly <NUM> may be included in a common assembly that is movable along the working axis <NUM>. Further, while reference is made herein to additive manufacturing systems including a print assembly <NUM> that dispenses a binder <NUM>, it should be understood that this is merely an example. For example, in some embodiments, instead of building objects with a curable binder <NUM> applied to the build material <NUM>, in some embodiments, a laser or other energy source may be applied to the build material <NUM> to fuse the build material <NUM>.

Referring to <FIG>, to form an object, layers of build material 31AA-31DD may be sequentially positioned on top of one another. In the example provided in <FIG>, sequential layers of binder 500AA-500CC are positioned on the layers of build material 31AA-31DD. By curing the layers of binder 50AA-50CC, a finished product may be formed.

Referring to <FIG>, a perspective view of one embodiment of the recoat assembly <NUM> is schematically depicted. The recoat assembly <NUM>, in embodiments, may include a recoat assembly transverse actuator <NUM> that moves the recoat assembly <NUM> in the lateral direction (i.e., in the +/- X-direction as depicted in the figure). In some embodiments, the recoat assembly <NUM> may further include additional actuators that move the recoat assembly in the vertical direction (i.e., in the +/-Z-direction as depicted in the figure), in a longitudinal direction (i.e., in the +/- Y-direction as depicted in the figure), and/or that may rotate the recoat assembly about any or all of the lateral direction, the vertical direction, and the longitudinal direction.

Referring to <FIG>, a section view of the recoat assembly <NUM> is schematically depicted. In embodiments, the recoat assembly <NUM> includes one or more powder distributing members that distribute build material <NUM> (<FIG>). For example, in the embodiment depicted in <FIG>, the recoat assembly <NUM> includes one or more rollers, in particular, a first roller <NUM> and a second roller <NUM>. While in the embodiment depicted in <FIG>, the recoat assembly <NUM> includes the first roller <NUM> and the second roller <NUM>, it should be understood that this is merely an example, and the recoat assembly <NUM> may include more rollers or may include a single roller. Further, while the powder spreading member depicted in <FIG> includes one or more rollers, it should be understood that the powder spreading member may include any suitable structure for spreading build material <NUM> (<FIG>), for example and without limitation, a doctor blade or the like.

In some embodiments, the recoat assembly <NUM> generally includes one or more energy sources that are structurally configured to apply generally emit electromagnetic radiation, such as infrared radiation, ultraviolet radiation, or the like. In some embodiments, the recoat assembly <NUM> may include a first energy source <NUM> and/or a second energy source <NUM> that may emit energy that heats build material <NUM> (<FIG>) and/or cures binder <NUM> (<FIG>) on the build material <NUM>, as described in greater detail herein.

In the embodiment depicted in <FIG>, the first energy source <NUM> is an outer energy source and the second energy source <NUM> is an inner energy source positioned closer to the powder spreading members (e.g., the first roller <NUM> and the second roller <NUM>) than the first energy source <NUM> (i.e., in the -X-direction as depicted in the figure). The first energy source <NUM> and the second energy source <NUM> generally emit energy toward build material <NUM> (<FIG>) positioned beneath the first energy source <NUM> and the second energy source <NUM> (e.g., in the - Z-direction as depicted in the figure). By emitting energy toward the build material <NUM> (<FIG>), the first energy source <NUM> and/or the second energy source <NUM> may heat the build material <NUM> (<FIG>) before binder <NUM> (<FIG>) is applied to the build material <NUM>, and may be used to "pre-heat" the build material <NUM>. In some embodiments, by emitting energy toward the build material <NUM> (<FIG>), the first energy source <NUM> and/or the second energy source <NUM> may assist in curing the binder <NUM> (<FIG>) to the build material <NUM> (<FIG>). While in the embodiment depicted in <FIG>, the recoat assembly <NUM> includes the first energy source <NUM> and the second energy source <NUM>, it should be understood that this is merely an example and recoat assemblies according to the present application may include any suitable number of energy sources and may include a single energy source.

Referring to <FIG>, in embodiments, the first energy source <NUM> and the second energy source <NUM> are positioned at least partially within a housing assembly <NUM>. For example, and referring particularly to <FIG> and <FIG>, in embodiments, the first energy source <NUM> and the second energy source <NUM> are embodied as radiation-emitting bulbs positioned at least partially within the housing assembly <NUM>. In embodiments, the housing assembly <NUM> includes an upper housing <NUM> that at least partially defines a duct <NUM>, and a lower housing <NUM> at least partially defines an energy source enclosure <NUM>. In embodiments, the first energy source <NUM> and/or the second energy source <NUM> are positioned at least partially within the energy source enclosure <NUM>. The duct <NUM> is in communication with an air distribution system <NUM> that is structurally configured to pass a gas, such as air, an inert gas or gases, or the like to the duct <NUM>. In some embodiments, the housing assembly <NUM> may be coupled to the recoat assembly <NUM> through one or more thermally insulating materials (e.g., gaskets and/or the like) that restrict the flow of thermal energy from the housing assembly <NUM> to the recoat assembly <NUM>.

For example and referring particularly to <FIG>, <FIG>, and <FIG>, the air distribution system <NUM> generally includes a pump <NUM> that moves gas to the duct <NUM>. In embodiments, the pump <NUM> may be configured to move gas to the duct <NUM> at rate of at least about <NUM> liters per minute, however, it should be understood that the pump <NUM> may move gas to the duct <NUM> at any suitable rate. In some embodiments, the pump <NUM> may be in communication with a distribution hose <NUM> that is in communication with the duct <NUM>. In some embodiments, the distribution hose <NUM> may include one or more "splits" such that the distribution hose <NUM> may pass gas from the pump <NUM> along the duct <NUM> (e.g., along the duct <NUM> in the +/- Y-direction as depicted in the figure). The duct <NUM> is in communication with the energy source enclosure <NUM>, such that gas passed from pump <NUM> to the duct <NUM> can be passed from the duct <NUM> to the energy source enclosure <NUM>. As gas is passed from the pump <NUM> to the duct <NUM>, the gas may be distributed along a length of the duct <NUM> (e.g., along the duct <NUM> in the +/- Y-direction as depicted in the figure) before being passed to the energy source enclosure <NUM>. Gas can flow from the duct <NUM> to the energy source enclosure <NUM>, for example through one or more apertures <NUM> positioned between the duct <NUM> and the energy source enclosure <NUM>. As shown in <FIG>, the one or more apertures <NUM> may extend along a length of the duct <NUM>, for example in the +/Y-direction as depicted in the figure. In some embodiments, the upper housing <NUM> and/or the lower housing may define one or more vents <NUM> through which gas may also pass.

As the gas passes through the one or more apertures <NUM>, the gas can then flow around the first energy source <NUM> and/or the second energy source <NUM>, as shown in <FIG> and <FIG>. The gas transfers thermal energy through forced convection from the first energy source <NUM> and/or the second energy source <NUM> to the build material <NUM> and/or the binder <NUM> positioned below the first energy source <NUM> and/or the second energy source <NUM>. In this way, the air distribution system <NUM>, the duct <NUM>, and the energy source enclosure <NUM> may assist in transferring and/or distributing thermal energy from the first energy source <NUM> and/or the second energy source <NUM> to the build material <NUM> and/or binder <NUM>.

The build material <NUM> and/or the binder <NUM> receives thermal energy via radiation emitted from the first energy source <NUM> and/or the second energy source <NUM>. The gas passed over the first energy source <NUM> and/or the second energy source <NUM> may supplement the thermal energy applied to the build material <NUM> and/or the binder <NUM> via radiation. In some embodiments, the build material <NUM> and/or the binder <NUM> may be primarily heated via radiation from the first energy source <NUM> and/or the second energy source <NUM>, while the gas passed over the first energy source <NUM> and/or the second energy source <NUM> supplements the energy transferred via radiation. In embodiments, the air distribution system <NUM> may increase the heat density applied to the build material <NUM> and/or the binder <NUM> by the first energy source <NUM> and/or the second energy source <NUM> and/or may increase the area of thermal energy applied by the first energy source <NUM> and/or the second energy source <NUM>. In some embodiments, the air distribution system <NUM> may assist in maintaining a stable boundary layer close to the build material <NUM> and/or binder <NUM>, for example, by more evenly distributing thermal energy applied by the first energy source <NUM> and/or the second energy source <NUM> as compared to systems that do not include an air distribution system <NUM>. Furthermore, by passing gas over the first energy source <NUM> and/or the second energy source <NUM>, heat that would otherwise dissipate and be lost may be utilized to heat the build material <NUM> and/or build material <NUM>, thereby increasing the energy efficiency of the first energy source <NUM> and/or the second energy source <NUM>.

By more efficiently transferring thermal energy from the first energy source <NUM> and/or the second energy source <NUM> to build material <NUM> and/or binder <NUM>, the air distribution system <NUM> may assist in curing the binder <NUM> more quickly than additive manufacturing systems that do not include an air distribution system <NUM>.

For example and referring to <FIG>, <FIG>, and <FIG>, in embodiments in which the first energy source <NUM> and the second energy source <NUM> are coupled to the recoat assembly <NUM>, the first energy source <NUM> and the second energy source <NUM> move over the build material <NUM> and/or the binder <NUM> as the recoat assembly <NUM> moves along the working axis <NUM>. Accordingly, the first energy source <NUM> and the second energy source <NUM> generally apply thermal energy to the build material <NUM> and/or the binder <NUM> while moving along the working axis <NUM>. To minimize the amount of time to build an object, it may be desirable to move the recoat assembly <NUM> along the working axis <NUM> as fast as practicable to adequately move the build material <NUM> to the build receptacle <NUM>. However, as the speed of the recoat assembly <NUM> along the working axis <NUM> increases, the time that the first energy source <NUM> and the second energy source <NUM> are positioned over any particular portion of build material <NUM> and/or binder <NUM> decreases. As the amount of time that the first energy source <NUM> and the second energy source <NUM> are positioned over any particular portion of build material <NUM> and/or binder <NUM> decreases, the amount of thermal energy transferred from the first energy source <NUM> and the second energy source <NUM> to the build material <NUM> and binder <NUM> decreases. Accordingly, while increasing the speed of the recoat assembly <NUM> along the working axis <NUM> may reduce the amount of time to build an object, the build material <NUM> and the binder <NUM> may not be adequately heated by the first energy source <NUM> and the second energy source <NUM>.

However, because the air distribution system <NUM> assists in transferring thermal energy from the first energy source <NUM> and the second energy source <NUM>, sufficient thermal energy may be applied to the build material <NUM> and the binder <NUM> while the recoat assembly <NUM> is moved along the working axis <NUM> at high speeds, as compared to conventional additive manufacturing systems that do not include the air distribution system <NUM>.

Further, in some instances, the air distribution system <NUM> may allow the first energy source <NUM> and/or the second energy source <NUM> to be operated at a reduced power while still providing a similar amount of energy to the build material <NUM> and the binder <NUM> as configurations that do not include the air distribution system <NUM>. By operating the first energy source <NUM> and/or the second energy source <NUM> at reduced power, a usable life of the first energy source <NUM> and/or the second energy source <NUM> may be increased as compared to conventional configurations.

Furthermore, in embodiments, the air distribution system <NUM> may dissipate heat transferred from the first energy source <NUM> and/or the second energy source <NUM> to the lower housing <NUM> and/or the upper housing <NUM>, thereby cooling the lower housing <NUM> and/or the upper housing <NUM>. In some embodiments, components (e.g., sensors and the like) of the recoat assembly <NUM> may be positioned proximate to and/or may be coupled to the lower housing <NUM> and/or the upper housing <NUM>. By cooling the lower housing <NUM> and/or the upper housing <NUM>, the air distribution system <NUM> may reduce the likelihood of overheating and damaging components (e.g., sensors and the like) of the recoat assembly <NUM> coupled to or positioned proximate to the lower housing <NUM> and/or the upper housing <NUM>. In embodiments in which the upper housing <NUM> and/or the lower housing <NUM> define the vents <NUM>, gas may additionally be passed through the vents <NUM>, which may also assist in cooling components (e.g., sensors and the like) of the recoat assembly <NUM> coupled to or positioned proximate to the lower housing <NUM> and/or the upper housing <NUM>.

While in the embodiment described above and depicted in <FIG> the air distribution system <NUM> passes gas around the first energy source <NUM> and the second energy source <NUM> coupled to the recoat assembly <NUM>, it should be understood that this is merely an example. In some embodiments, energy sources may additionally or alternatively be positioned within housing assemblies coupled to the print assembly <NUM>, and the air distribution system <NUM> and/or another air distribution system may pass gas around the energy sources coupled to the print assembly <NUM>.

Referring to <FIG>, in some embodiments, the first energy source <NUM> and the second energy source <NUM> are positioned on opposite sides of the first and second rollers <NUM>, <NUM> (i.e., in the -X-direction as depicted). In these embodiments, the first energy source <NUM> may be at least partially enclosed within a first housing assembly <NUM> including a first duct <NUM> in communication with the air distribution system <NUM> and a first energy source enclosure <NUM>, as described above. However, in the embodiment depicted in <FIG>, the second energy source <NUM> is at least partially enclosed within a second housing assembly <NUM>' that is separate from the first housing assembly <NUM>. The second housing assembly <NUM>' may include a second upper housing <NUM>' that defines a second duct <NUM>', and a second lower housing <NUM>' that defines a second energy source enclosure <NUM>'. In embodiments, the second duct <NUM>' may be in communication with the air distribution system <NUM>, and the second housing assembly <NUM>' operate in a similar manner to the housing assembly <NUM> described above and depicted in <FIG> and <FIG> to transfer and distribute energy from the second energy source <NUM> through forced convection.

Referring to <FIG>, an example control diagram for the additive manufacturing system <NUM>. As illustrated, the additive manufacturing system <NUM> includes a controller <NUM> including a processor <NUM>, a data storage component <NUM>, and/or a memory component <NUM>. The memory component <NUM> may be configured as volatile and/or nonvolatile memory and as such, may include random access memory (including SRAM, DRAM, and/or other types of RAM), flash memory, secure digital (SD) memory, registers, compact discs (CD), digital versatile discs (DVD), and/or other types of non-transitory computer-readable mediums. Depending on the particular embodiment, these non-transitory computer-readable mediums may reside within the controller <NUM> and/or external to the controller <NUM>.

The memory component <NUM> may store operating logic, analysis logic, and communication logic in the form of one or more computer readable and executable instruction sets. The analysis logic and the communication logic may each include a plurality of different pieces of logic, each of which may be embodied as a computer program, firmware, and/or hardware, as an example. A local interface may also be included in the controller <NUM>, and may be implemented as a bus or other communication interface to facilitate communication among the components of the controller <NUM>.

The processor <NUM> may include any processing component operable to receive and execute instructions (such as from a data storage component <NUM> and/or the memory component <NUM>). It should be understood that while the components in <FIG> are illustrated as residing within the controller <NUM>, this is merely an example, and in some embodiments, one or more of the components may reside external to the controller <NUM>. It should also be understood that, while the controller <NUM> is illustrated as a single device, this is also merely an example.

In embodiments, the controller <NUM> is communicatively coupled to one or more components of the additive manufacturing system. For example, in the embodiment depicted in <FIG>, the controller <NUM> is communicatively coupled to the first energy source <NUM>, the second energy source <NUM>, the air distribution system <NUM>, the recoat assembly transverse actuator <NUM>, and one or more roller actuators <NUM>.

The controller <NUM> may send signals to the first energy source <NUM> and/or the second energy source <NUM> that cause the first energy source <NUM> and/or the second energy source <NUM> to emit energy, irradiating build material <NUM> (<FIG>) positioned beneath the first energy source <NUM> and/or the second energy source <NUM>. In some embodiments, the controller <NUM> may further send signals to the first energy source <NUM> and/or the second energy source <NUM> that can change an intensity of the energy emitted by the first energy source <NUM> and/or the second energy source <NUM>.

The controller <NUM> may send signals to the air distribution system <NUM> that causes the air distribution system <NUM> to induce gas flow to the first energy source <NUM> and/or the second energy source <NUM>, as described above. For example, the controller <NUM> may be communicatively coupled to the pump <NUM> or the like that induces the flow of gas through the air distribution system <NUM>. In some embodiments, the controller <NUM> may send signals to the air distribution system <NUM> that changes a volume and/or velocity of the flow of gas through the air distribution system.

In embodiments, the controller <NUM> may send signals to the recoat assembly transverse actuator <NUM> causing the recoat assembly transverse actuator <NUM> to move the recoat assembly <NUM> (<FIG>) along the working axis <NUM> (<FIG>).

In some embodiments, the controller <NUM> may send signals to the one or more roller actuators <NUM> that are coupled to and cause the one or more roller actuators <NUM> to rotate the first roller <NUM> (<FIG>) and/or the second roller <NUM> (<FIG>).

In some embodiments, one or more sensors <NUM> are communicatively coupled to the controller <NUM>. The one or more sensors <NUM> may one or more temperature sensors such as thermocouples, resistance temperature detectors (RTDs), infrared pyrometers, or the like. The one or more sensors <NUM> may send signals to the controller <NUM> indicative of detected temperatures at various locations within the additive manufacturing system <NUM>. In embodiments, the controller <NUM> may direct various components of the additive manufacturing system <NUM> (e.g., the first energy source <NUM>, the second energy source <NUM>, the recoat assembly transverse actuator <NUM>, the air distribution system <NUM>, etc.) in response to temperatures detected via the one or more sensors <NUM>.

Referring to <FIG>, <FIG>, <FIG>, and <FIG>, in some embodiments, the recoat assembly <NUM> may include a powder plow assembly <NUM> that may assist in moving excess build material <NUM> (<FIG>) and/or debris positioned in the path of the recoat assembly <NUM> as the recoat assembly <NUM> moves along the working axis <NUM>. For example, in some circumstances, the recoat assembly <NUM> may move more build material <NUM> (<FIG>) than is necessary to achieve a desired layer thickness, as described in greater detail herein. In some circumstances, debris may be positioned in the path of the recoat assembly <NUM>. The powder plow assembly <NUM> may move this debris or excess build material <NUM> (<FIG>) such that the debris or excess build material <NUM> does not contact or interfere with components of the recoat assembly <NUM>. For example, in some embodiments, the one or more sensors <NUM> may be positioned inward (e.g., in the -x-direction as depicted) of the powder plow assembly <NUM>. As the recoat assembly moves, for example in the +x-direction as depicted, the powder plow assembly <NUM> may contact and move build material <NUM> (<FIG>) and/or debris that would otherwise contact and may damage or interfere with the one or more sensors <NUM>. Although the powder plow <NUM> is shown as only being on one side of the recoat assembly <NUM>, it should be appreciated that, in embodiments, a second powder plow assembly <NUM> may be provided on the opposite side of the recoat assembly (e.g., in the x-direction as depicted).

The powder plow <NUM> may be formed from any suitable material with a wear resistant low coefficient of friction coating. As a non-limiting example, the powder plow <NUM> may be formed from electroless nickel with co-deposited polytetrafluoroethylene (PTFE) or may be electropolished.

Referring now to <FIG>, a perspective view and a side view of the powder plow assembly <NUM> are depicted with a cover of the powder plow assembly <NUM> removed, respectively. In embodiments, the powder plow assembly <NUM> includes at least one actuator <NUM> for moving the powder plow <NUM> between a raised position and a lowered position (e.g., moving the powder plow <NUM> in the +/- Z-direction as depicted in the figure). Any suitable actuators may be used such as, for example, electric actuators, pneumatic actuators, hydraulic actuators, spring actuators, or any other suitable actuating device.

Methods for operating the recoat assembly <NUM> will now be described with reference to the appended drawings. In some embodiments, the controller <NUM> may direct the recoat assembly <NUM> to perform the methods described below.

Referring to <FIG> a side view of the recoat assembly <NUM> is depicted. The recoat assembly <NUM> moves in a coating direction <NUM> over the supply receptacle <NUM> including the build material <NUM>. The recoat assembly <NUM> contacts the build material <NUM> in the supply receptacle <NUM> within the supply receptacle <NUM> with the powder spreading member, which in the embodiment depicted in <FIG> includes the first roller <NUM> and/or the second roller <NUM>. In some embodiments, the first roller <NUM> and/or the second roller <NUM> may be rotated, for example in a counter-rotation direction <NUM> such that a bottom of the first roller <NUM> and/or the second roller <NUM> moves in the coating direction <NUM>. As noted above, in some embodiments, the powder spreading member may include a doctor blade or the like.

The recoat assembly, via the powder spreading member (e.g., the first roller <NUM> and/or the second roller <NUM>), moves build material <NUM> in the coating direction <NUM> from the supply receptacle <NUM> to a build area (e.g., the build receptacle <NUM>) which is spaced apart from the supply receptacle <NUM>. In embodiments, the powder spreading member (e.g., the first roller <NUM> and/or the second roller <NUM>) deposits a second layer of build material <NUM> over an initial layer of build material <NUM> positioned in the build receptacle <NUM>, for example as the result of a previous cycle of the recoat assembly <NUM>.

For example and referring to <FIG>, the powder spreading member (e.g., the first roller <NUM> and/or the second roller <NUM>) may deposit a second layer of build material <NUM> over an initial layer of build material <NUM>I previously deposited by the powder spreading member in the build receptacle <NUM>.

In embodiments, the powder spreading member (e.g., the first roller <NUM> and/or the second roller <NUM>) contacts the second layer of build material <NUM>, and moves at least a portion of the second layer of build material <NUM>S in a return direction <NUM> back to the supply receptacle <NUM>. The powder spreading member (e.g., the first roller <NUM> and/or the second roller <NUM>) then deposits at least a portion of the second layer of build material <NUM>S into the supply receptacle <NUM>. In some embodiments, the at least a portion of the second layer of build material <NUM>S can be deposited directly in the supply receptacle <NUM> by the powder spreading member (e.g., the first roller <NUM> and/or the second roller <NUM>). In some embodiments, the additive manufacturing system <NUM> may include a return chute <NUM> in communication with the supply receptacle <NUM>, and the at least a portion of the second layer of build material <NUM> may be deposited within the return chute <NUM>.

Accordingly, in embodiments an initial thickness of the second layer of build material <NUM>S may be greater than a final thickness of the build material <NUM> that remains after the at least a portion of the second layer of build material <NUM>S is moved back to the supply receptacle <NUM> by the recoat assembly <NUM>. By initially depositing an excess amount of build material <NUM> to form the second layer of build material <NUM>, voids within the second layer of build material <NUM> can be reduced. Further, by initially depositing an excess amount of build material <NUM> to form the second layer of build material <NUM>, forces applied to the initial layer of build material <NUM>I and/or cured binder <NUM> (<FIG>) within the initial layer of build material <NUM>I can be reduced. Additionally, by returning excess build material <NUM> to the supply receptacle <NUM> (either directly or via the return chute <NUM>), the excess build material <NUM> can be readily re-used in subsequent layers of build material <NUM> deposited in the build receptacle <NUM>.

In some embodiments, the first energy source <NUM> and/or the second energy source <NUM> may irradiate the initial layer of build material <NUM>I and/or the second layer of build material <NUM> positioned within the build area (e.g., the build receptacle <NUM>).

Based on the foregoing, it should be understood that embodiments described herein are directed to additive manufacturing systems that generally include a recoat assembly for spreading build material in a build area. The recoat assembly may move build material from a build supply to the build area in sequential layers. In embodiments, the recoat assembly may move the excess build material back to the build supply such that the excess build material may be utilized in subsequent layers. In some embodiments, the recoat assembly and/or print assembly may include one or more energy sources that can apply energy to the build material. According to the claimed invention, an air distribution system distributes heat generated by the one or more energy sources by forced convection.

Claim 1:
A method for forming an object, the method comprising:
moving a recoat assembly (<NUM>) in a coating direction (<NUM>) over a supply receptacle (<NUM>) comprising build material (<NUM>), wherein the recoat assembly (<NUM>) comprises a powder spreading member;
contacting the build material (<NUM>) in the supply receptacle (<NUM>) with the powder spreading member;
irradiating, with an energy source (<NUM>, <NUM>) coupled to the recoat assembly (<NUM>), an initial layer of build material (<NUM>) positioned in a build receptacle (<NUM>); and
passing a gas over the energy source, thereby heating the initial layer of build material (<NUM>) positioned in the build receptacle (<NUM>) via forced convection.