Researchers Submit Patent Application, "Pneumatic Jetting of Metal for Additive Manufacturing", for Approval (USPTO 20170252808)

Robotics & Machine Learning |

By a News Reporter-Staff News Editor at Robotics & Machine Learning -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Myerberg, Jonah Samuel (Lexington, MA); Natchurivalapil Rappai James, Toshana Krishna (Somerville, MA); Sachs, Emanuel Michael (Newton, MA); Hoisington, Paul A. (Hanover, NH); Li, Kevin Michael (Brighton, MA), filed on , was made available online on .

No assignee for this patent application has been made.

News editors obtained the following quote from the background information supplied by the inventors: "Pneumatic jetting can be used to drive droplets of metal with pressurized air or gas. Such droplets can be accumulated to form an object. While pneumatic jetting can impart forces to liquid metal to form a metallic object, considerations related to speed, accuracy, control, and material properties present challenges for the use of pneumatic forces for object formation on a large scale. Accordingly, there remains a need for commercially viable techniques for additive manufacturing of metal using pneumatic forces."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "Devices, systems, and methods are directed to the pneumatic ejection of liquid metal from a nozzle moving along a controlled three-dimensional pattern to fabricate a three-dimensional object through additive manufacturing. The metal is movable into the nozzle as a valve is actuated to control movement of pressurized gas into the nozzle. Such movement of metal into the valve as pressurized gas is being moved into the nozzle to create an ejection force on liquid metal in the nozzle can reduce or eliminate the need to replenish a supply of the metal in the nozzle and, therefore can facilitate continuous or substantially continuous liquid metal ejection for the fabrication of parts.

"An additive manufacturing system may include a nozzle defining a volume and a discharge orifice in fluid communication with one another, a source of a pressurized gas, a valve actuatable to control fluid communication between the source of pressurized gas and the volume of the nozzle, and a media supply in fluid communication with the volume of the nozzle. Metal from the media supply may be movable into the volume of the nozzle as the valve is actuated to eject, under pneumatic force of the pressurized gas in the nozzle, a liquid form of the metal from the discharge orifice along a controlled three-dimensional pattern associated with fabrication of a three-dimensional object.

"Implementations may include one or more of the following features. Metal from the media supply may be movable into the volume while the valve is positioned to interrupt fluid communication between the discharge orifice of the nozzle and the source of the pressurized gas. The nozzle may further define a first port and a second port, the first port and the second port spaced apart from one another along the volume of the nozzle, the actuation of the valve controlling movement of the pressurized gas into the volume of the nozzle through the first port. The first port and the second port may be substantially axially aligned with one another along the volume of the nozzle. The media supply may be in fluid communication with the volume of the nozzle through the second port. The second port may be vented to the atmosphere. The second port may be vented to a vacuum. The system may further include a media drain in fluid communication with the volume of the nozzle, where the metal from the media supply is movable from the volume of the nozzle to the media drain. The discharge orifice and the first port may be positioned relative to one another such that metal moving from the media supply to the media drain moves between the discharge orifice and the first port. The system may further include a heater arranged to heat at least a portion of the nozzle adjacent to the discharge orifice. The heater may be one or more of a resistance heater and an induction heater. The metal supply may be movable into a portion of the volume adjacent to the discharge orifice. The system may further include an inert gas curtain disposed at least partially around the discharge orifice.

"A method of additive manufacturing may include directing a metal into a volume defined by a nozzle, and moving a discharge orifice and a build plate relative to one another along a controlled three-dimensional pattern, where the discharge orifice is defined by the nozzle and in fluid communication with the volume. The method may also include, based at least in part on a position of the discharge orifice along the controlled three-dimensional pattern, selectively delivering pulses of pressurized gas into the volume to eject a liquid form of the metal from the discharge orifice to form a three-dimensional object on the build plate, where the metal is directed into the volume defined by the nozzle as the pulses of pressurized gas are selectively delivered into the volume.

"Implementations may include one or more of the following features. Selectively delivering pulses of pressurized gas into the volume to eject the liquid form of the metal may include ejecting the liquid form of the metal from the discharge orifice in a direction having a vertical component opposite a direction of gravity. The method may further include heating the nozzle at least along a portion of the nozzle defining the discharge orifice. Directing the metal into the volume defined by the nozzle may include directing a solid form of the metal into the nozzle. The method may further include venting the pressurized gas from the volume of the nozzle through a port defined by the nozzle and in fluid communication with the atmosphere or a vacuum. Directing the metal into the volume may include moving the metal into the volume through the port. The pressurized gas may be inert with respect to the metal. The method may further include draining the liquid metal from the volume of the nozzle as the pulses of pressurized gas are selectively delivered into the volume. The liquid form of the metal may be ejected into one or more of an inert atmosphere and a vacuum housed within a build chamber during fabrication of the three-dimensional object. The method may further include adjusting the discharge orifice to control a meniscus of the liquid form of the metal at the discharge orifice.

"Devices, systems, and methods are directed to adjusting a pneumatic circuit associated with pneumatic ejection of liquid metal from a nozzle as the nozzle moves along a controlled three-dimensional pattern to fabricate a three-dimensional object. The adjustment of the pneumatic circuit can facilitate adjusting a pressure profile within the nozzle as pressurized gas moves through the nozzle to eject, through pneumatic force, liquid metal from the nozzle. Through adjustment of the pneumatic circuit, characteristics of the liquid metal (e.g., size, shape, and flow rate) can be controlled to facilitate control over fabrication of the three-dimensional object.

"An additive manufacturing system may include a nozzle defining a volume and a discharge orifice in fluid communication with one another, the nozzle including an exhaust passage in fluid communication with the volume. The system may also include a source of a pressurized gas in selective fluid communication with the volume of the nozzle, and a media supply in fluid communication with the volume of the nozzle such that metal from the media supply is movable into the volume, where the exhaust passage has an adjustable back pressure to control a pressure profile in the volume of the nozzle as the pressurized gas moves through the volume to eject a liquid form of the metal from the discharge orifice along a controlled three-dimensional pattern for fabrication of a three-dimensional object.

"Implementations may include one or more of the following features. The exhaust passage may include a hydraulic inductance, the hydraulic inductance having a dissipating resistance to flow in response to force exerted, over a period of time, on the hydraulic inductance by venting pressurized gas in the exhaust passage. The hydraulic inductance may include a paddle wheel rotatable in response to force exerted on the paddle wheel by venting pressurized gas in the exhaust passage. The paddle wheel may be rotatable in response to force exerted on the paddle wheel by venting pressurized gas in the exhaust passage. A time-varying profile of the resistance of the hydraulic inductance may be adjustable. The exhaust passage may include a variable hydraulic resistance. The variable hydraulic resistance may include a variable length of the exhaust passage. The variable hydraulic resistance may include a flow restriction having a variable size. The system may further include a valve in fluid communication with the source of the pressurized gas and the volume, where the valve is actuatable to deliver pulses of the pressurized gas to the volume.

"A method of additive manufacturing may include directing a metal into a volume defined by a nozzle, the volume in fluid communication with an exhaust passage defined by the nozzle. The method may also include moving a discharge orifice and a build plate relative to one another along a controlled three-dimensional pattern, the discharge orifice defined by the nozzle and in fluid communication with the volume. The method may also include delivering pulses of pressurized gas into the volume of the nozzle, and adjusting a back pressure of the exhaust passage through which the pressurized gas is vented from the volume of the nozzle, where, in response to the adjustment of the back pressure, the pressurized gas in the volume exerts a force on a liquid form of the metal in the nozzle to eject the liquid metal from the discharge orifice as the discharge orifice and the build plate are moved relative to one another along the controlled three-dimensional pattern to form a three-dimensional object on the build plate.

"Implementations may include one or more of the following features. Adjusting the back pressure of the exhaust passage may include venting the pressurized gas through a hydraulic inductance having a dissipating resistance to flow in response to force exerted, over a period of time, on the hydraulic inductance by the venting pressurized gas in the exhaust passage. Dissipating resistance may dissipate to a substantially constant hydraulic resistance over the period of time. The period of time may be less than a period of the pulses of pressurized gas delivered into the volume of the nozzle. The hydraulic inductance may include a paddle wheel rotatable in response to force exerted on the paddle wheel by the venting pressurized gas in the exhaust passage. Adjusting the back pressure of the exhaust passage may include venting the pressurized gas through a variable hydraulic resistance and adjusting the variable hydraulic resistance based at least in part on a position of the discharge orifice with respect to the controlled three-dimensional pattern. The variable hydraulic resistance may include a flow restriction having a variable size and varying the variable hydraulic resistance may include changing the size of the flow restriction. The variable hydraulic resistance may include a variable length of the exhaust passage and varying the variable hydraulic resistance may include changing the length of the exhaust passage. Adjusting the back pressure of the exhaust passage may be based on a volume of the liquid form of the metal in the volume of the nozzle. The exhaust passage may be vented to at least one of atmospheric pressure and a vacuum. The metal may be directed into the volume through the exhaust passage. The method may also include tuning the pulses of pressurized gas in a multiple of a natural harmonic of the volume of the nozzle.

"Devices, systems, and methods are directed to separating sediment from liquid metal ejected, through pneumatic force, from a nozzle moving along a controlled three-dimensional pattern to fabricate a three-dimensional object. The separation of the sediment from the liquid metal can reduce the likelihood that the nozzle will become clogged or otherwise degraded during fabrication of the three-dimensional object or over the course of fabrication of multiple objects. Accordingly, the separation of the sediment from the liquid metal can facilitate, for example, the use of pneumatic ejection of liquid metal for high volume production of parts.

"An additive manufacturing system may include a nozzle defining a volume, a first port, a second port, and a discharge orifice in fluid communication with one another. The system may also include a source of a pressurized gas in selective fluid communication with the volume of the nozzle through the first port, a media supply in fluid communication with the volume of the nozzle through the second port, and one or more baffles disposed in the volume of the nozzle such that an axis defined by the discharge orifice and the second port intersects the one or more baffles, the one or more baffles oriented to direct sediment of a liquid form of a metal in the volume to a reservoir portion of the volume, the reservoir portion away from the discharge orifice.

"Implementations may include one or more of the following features. The one or more baffles may define a non-linear path between the discharge orifice and the reservoir portion of the volume. The non-linear path between the discharge orifice and the reservoir portion of the volume may include an increase in height, along an axis perpendicular to the discharge orifice, along the non-linear path from the reservoir portion to the discharge orifice. The one or more baffles may span a dimension of the volume. The one or more baffles may include a plurality of baffles substantially parallel to one another. The one or more baffles may be angled with respect to an axis perpendicular to the discharge orifice. The media supply may be configured to move a solid form of metal into the volume through the second port. The second port may be vented to atmosphere such that pressurized gas exits the volume through the second port. A flow of pressurized gas through the first port may be substantially unimpeded by the one or more baffles. The system may also include a heater arranged to heat at least portions of the nozzle defining the discharge orifice and along which the one or more baffles are disposed. The heater may include one or more of a resistance heater, an induction heater, a convection heater, and a radiation heater.

"A method of additive manufacturing may include directing a metal into a volume defined by a nozzle, and moving a discharge orifice and a build plate relative to one another along a controlled three-dimensional pattern, where the discharge orifice is defined by the nozzle and in fluid communication with the volume. The method may also include separating, in the volume, a liquid form of the metal from a sediment. Based at least in part on a position of the discharge orifice along the controlled three-dimensional pattern, the method may also include delivering pressurized gas into the volume to eject the liquid form of the metal from the discharge orifice to form a three-dimensional object on the build plate.

"Implementations may include one or more of the following features. Separating the liquid form of the metal from the sediment may include moving the liquid form of the metal along a non-linear path from a sediment reservoir in the volume to the discharge orifice. Separating the liquid form of the metal from the sediment may further include increasing, in the volume, a height of the liquid form of the metal relative to the discharge orifice. The non-linear path may be at least partially defined by one or more baffles disposed in the volume. The liquid form of the metal may be separated from the sediment as the pressurized gas is delivered into the volume.

"Devices, systems, and methods are directed to switching between pneumatically actuated ejection and electrically actuated ejection of liquid metal from a nozzle moving along a controlled three-dimensional pattern to fabricate a three-dimensional object. Electrically actuated ejection can be useful, for example, for delivering discrete droplets in areas of the object requiring a high degree of accuracy. Pneumatic ejection can be useful, for example, for delivering a stream of liquid metal from the nozzle to provide liquid metal rapidly to areas of the object that require less accuracy (e.g., an inner portion of the object). Accordingly, switching between pneumatically actuated ejection and electrically actuated ejection can facilitate accurate and rapid production of parts through additive manufacturing.

"A method of additive manufacturing may include directing a metal into a volume defined by a nozzle, and moving a discharge orifice and a build plate relative to one another along a controlled three-dimensional pattern, the discharge orifice defined by the nozzle and in fluid communication with the volume. The method may also include, based at least in part on a position of the discharge orifice along the controlled three-dimensional pattern, selectively switching between pneumatically actuated ejection and electrically actuated ejection of a liquid form of the metal from the discharge orifice. The method may also include ejecting the liquid form of the metal from the discharge orifice according to the selected one of the pneumatically actuated ejection and the electrically actuated ejection to form at least a portion of a three-dimensional object.

"Implementations may include one or more of the following features. Upon selection of the pneumatically actuated ejection, ejecting the liquid form of the metal from the discharge orifice may include ejecting a substantially constant stream of the liquid form of the metal from the discharge orifice. Upon selection of the electrically actuated ejection, ejecting the liquid form of the metal from the discharge orifice may include controlling a pulsed electrical current. Droplets of the liquid form of the metal may be ejected from the discharge orifice in response to the pulsed electrical current. Selectively switching between pneumatically actuated ejection and electrically actuated ejection may include selecting the electrically actuated ejection along a border of the controlled three-dimensional pattern and selecting the pneumatically actuated ejection along an excursion away from the border of the controlled three-dimensional pattern. Ejecting liquid metal from the discharge orifice according to pneumatically actuated ejection may include delivering pressurized air to the volume. The method may further include venting the pressurized air to one or more of the atmosphere and a vacuum as the liquid form of the metal is ejected through the discharge orifice. Ejecting liquid metal from the discharge orifice according to the electrically actuated ejection may include delivering an electric current into the liquid form of the metal. The electric current may result in a magnetohydrodynamic force exerted on the liquid form of the metal. The electric current may result in an electrohydrodynamic force exerted on the liquid form of the metal. Ejecting liquid metal from the discharge orifice according to the electrically actuated ejection may include delivering an electric current to an actuator in mechanical communication with the liquid form of the metal and movable in response to the electric current to exert a mechanical force on the liquid form of the metal to eject the liquid form of the metal from the discharge orifice. The actuator may include a piezoelectric element. The method may further include heating the metal in the volume at least along a portion of the volume defining the discharge orifice. Directing the metal into the volume may include moving the metal into the volume as the liquid form of the metal is discharged from the orifice. The method may further include draining the liquid form of the metal from the volume, through a media drain separate from the discharge orifice, as the liquid form of the metal is discharged from the orifice.

"An additive manufacturing system may include a nozzle defining a volume and a discharge orifice in fluid communication with one another, a build plate spaced apart from the discharge orifice of the nozzle, a source of a pressurized gas, an electrical power source, a valve actuatable to control fluid communication between the source of the pressurized gas and the volume of the nozzle, and a robotic system mechanically coupled to the nozzle, where the robotic system is movable to move the discharge orifice and the build plate relative to one another in three-dimensions. The system may also include a controller in electrical communication with the valve, the electrical power source, and the robotic system, the controller configured to actuate the robotic system to move the discharge orifice and the build plate relative to one another along a controlled three-dimensional pattern, and the controller further configured to activate the valve and the power source, based at least in part on a position of the discharge orifice along the controlled three-dimensional pattern, to selectively switch between pneumatically actuated ejection and electrically actuated ejection of a liquid form of a metal from the discharge orifice to form a three-dimensional object on the build plate.

"Implementations may include one or more of the following features. Selectively switching between pneumatically actuated ejection and electrically actuated ejection may include selecting the electrically actuated ejection along a border of the controlled three-dimensional pattern and selecting the pneumatically actuated ejection along an excursion away from the border of the controlled three-dimensional pattern. Upon selection of the pneumatically actuated ejection, the controller may actuate the valve to establish fluid communication between the source of the pressurized gas and the volume. Upon selection of the electrically actuated ejection, the controller may actuate the power source to deliver electric current to the volume. The controller may actuate the power source to deliver a pulsed electric current to the volume."

For additional information on this patent application, see: Myerberg, Jonah Samuel; Natchurivalapil Rappai James, Toshana Krishna; Sachs, Emanuel Michael; Hoisington, Paul A.; Li, Kevin Michael. Pneumatic Jetting of Metal for Additive Manufacturing. Filed and posted . Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220170252808%22.PGNR.&OS=DN/20170252808&RS=DN/20170252808

Keywords for this news article include: Patents, Robotics, Machine Learning, Emerging Technologies.

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