Patent Description:
Additive manufacturing is a process in which material is built up layer-by-layer to form a component. Stereolithography (SLA) is a type of additive manufacturing process that employs a tank of radiant-energy curable photopolymer "resin" and a curing energy source such as a laser. Similarly, Digital Light Processing (DLP) three-dimensional (3D) printing employs a two-dimensional image projector to build components one layer at a time. For each layer, the energy source draws or flashes a radiation image of the cross section of the component onto the surface of the resin or through a radiotransparent portion of a resin support. Exposure to the radiation cures and solidifies the pattern in the resin and joins it to a previously cured layer.

In some instances, additive manufacturing may be accomplished through a "tape casting" process. In this process, a resin is deposited onto a flexible radiotransparent tape or foil that is fed out from a supply reel to a build zone. Radiant energy is used to cure the resin to a component that is supported by a stage in the build zone. Once the curing of the first layer is complete, the stage and the foil are separated from one another. The foil is then advanced and fresh resin is provided to the build zone. In turn, the first layer of the cured resin is placed onto the fresh resin and cured through the energy device to form an additional layer of the component. Subsequent layers are added to each previous layer until the component is completed.

During the tape casting process, various processes may occur simultaneously within an additive manufacturing apparatus. Accordingly, it may be beneficial for various portions of the foil to move at different speeds and/or for a portion of the foil to move intermittently while other portions generally move continuously. As such, an accumulator device that is capable of creating additional functionality for additive manufacturing would be beneficial.

<CIT> discloses an additive manufacturing apparatus.

The invention is defined by the subject-matter of the appended claims.

According to the present invention, an additive manufacturing apparatus includes a feed module configured to operably couple with a first end portion of a foil. A take-up module is configured to operably couple with a second end portion of a foil. At least one stage is configured to hold one or more cured layers of a resin that form a component. A radiant energy device is positioned opposite to the at least one stage. The radiant energy device is operable to generate and project radiant energy in a predetermined pattern. An actuator is configured to change a relative position of the at least one stage and the foil. An accumulator is positioned between the feed module and the take-up module. The accumulator is configured to retain an intermediate portion of the foil to allow a first portion of the foil upstream of the accumulator to move at a first speed and a second portion of the foil downstream of the accumulator to move at a second speed during a defined time period. It further comprises a material retention assembly within the accumulator; wherein the material retention assembly includes a pneumatic actuation zone that is configured to selectively interact with the foil by producing a force on a first side of the foil, the first side of the foil being opposite the resin.

Acoording to the present invention, a method of operating an additive manufacturing apparatus is provided herein. The method includes moving a first portion of a foil a first distance during a defined time period. The first portion of the foil is positioned upstream of an accumulator. The method also includes moving a second portion of the foil a second distance during the defined time period. The second portion of the foil is positioned downstream of the accumulator. Moreover, the second distance is different from the first distance.

These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following description and appended claims.

A full and enabling disclosure of the present disclosure, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

As used herein, the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to signify a location or importance of the individual components. The terms "upstream" and "downstream" refer to the relative direction with respect to a foil (or resin support) movement along the manufacturing apparatus. For example, "upstream" refers to the direction from which the foil moves, and "downstream" refers to the direction to which the foil moves. As used herein, the term "selectively" refers to a component's ability to operate in various states (e.g., an ON state and an OFF state) based on manual and/or automatic control of the component.

The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

Accordingly, a value modified by a term or terms, such as "about," "approximately," "generally," and "substantially," is not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or apparatus for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a ten percent margin.

Moreover, the technology of the present application will be described in relation to exemplary embodiments.

For example, if a composition or assembly is described as containing components A, B, and/or C, the composition or assembly can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

The present disclosure is generally directed to an additive manufacturing apparatus that implements various manufacturing processes such that successive layers of material(s) are provided on each other to "build-up," layer-by-layer, a three-dimensional component. The successive layers generally cure together to form a monolithic component which may have a variety of integral sub-components. Although additive manufacturing technology is described herein as enabling the fabrication of complex objects by building objects point-by-point, layer-by-layer, typically in a vertical direction, variations of the described additive manufacturing apparatus and technology are possible and within the scope of the present subject matter.

The additive manufacturing apparatus can include a support plate, a window supported by the support plate, and a stage moveable relative to the window. The additive manufacturing apparatus can further include a flexible tape or foil that supports a resin. A radiant energy device is configured to cure a portion of the resin forming a layer of the component, which is translated towards and away from the foil by stage between successive curing operations.

In some instances, a feed module is configured to operably couple with a first end portion of a foil and a take-up module is configured to operably couple with a second end portion of a foil. The build zone may be positioned between the feed module and the take-up module. An accumulator may be positioned between the feed module and the take-up module and configured to alter the relative movement of a first portion of the foil upstream of the accumulator from a second portion of the foil downstream of the accumulator. For example, the first portion of the foil may be translated at a first speed while the second portion is translated at a second speed that is different from the first speed. As used herein, the "speed" of the foil may be a measurement of each portion of a foil (or other component) at a defined time period. The defined time period may be a predefined moment during a build process, such as when the foil is translated through at least one build zone, and/or at any other time during operation of the apparatus. Additionally, the defined time period may be a defined amount of time in which the speed of the foil is averaged over the amount of time. For example, the defined amount of time may be one second or any other amount of time. Further, when the speed of the foil is upstream of the accumulator, the speed may be measured at any point between the feed module and the accumulator. Likewise, when the speed of the foil is downstream of the accumulator, the speed may be measured at any point between the accumulator and the take-up module and/or a subsequent accumulator downstream of the first accumulator. Lastly, it will be appreciated that the speed of the foil within the accumulator may be varied from that of the speed of the foil upstream of the accumulator and/or downstream of the accumulator by altering an amount of foil within the accumulator. In instances in which the amount of foil within the accumulator is varied, the speed of the foil may be measured at any defined position within the accumulator. However, when not defined, the default position at which the speed of the foil within the accumulator is measured is a point at which the foil exits a cavity of the accumulator.

Additionally, or alternatively, one of the first or second portion of the foil may move continuously while the other of the first or second portion of the foil moves intermittently during a predefined time period. In some instances, the predefined time period may be an amount of time between at least two curing steps within a build zone. As various portions of the foil move independently, simultaneous processes may be occurring within the apparatus. For example, a curing process may be occurring on a first portion of the foil while a resin reclamation process is occurring on the second portion of the foil. By moving the first and second portions of the foil independently, at least during various portions of operation, the speed at which a component is printed may be increased, and/or any of the processes may be accomplished more efficiently.

Referring to the drawings wherein identical reference numerals denote the similar elements throughout the various views, <FIG> schematically illustrates an example of one type of suitable apparatus <NUM> for forming a component <NUM> created through one or more layers of cured resin R. The apparatus <NUM> can include one or more of a support plate <NUM>, a window <NUM>, a stage <NUM> that is movable relative to the window <NUM>, and a radiant energy device <NUM>, which, in combination, may be used to form any number (e.g., one or more) of additively manufactured components <NUM>.

In the illustrated example, the apparatus <NUM> includes a feed module <NUM>, which may include a first roller 22A, and a take-up module <NUM>, which may include a second roller 24A, that are spaced-apart and configured to couple with respective end portions of a flexible tape or foil <NUM> or another type of resin support extending therebetween. A portion of the foil <NUM> can be supported from underneath by the support plate <NUM> that defines a support plate upper surface <NUM>. Suitable mechanical supports (frames, brackets, etc.) may be provided for the rollers 22A, 24A and the support plate <NUM>. The first roller 22A and/or the second roller 24A can be configured to control the speed and direction of the foil <NUM> such that the desired tension and speed is maintained in the foil <NUM> through a drive system. By way of example and not limitation, the drive system can be configured as individual motors associated with the first roller 22A and/or the second roller 24A. Moreover, various components, such as motors, actuators, feedback sensors, and/or controls can be provided for driving the rollers 22A, 24A in such a manner so as to move at least a portion of the foil <NUM> between the rollers 22A, 24A.

In various embodiments, the window <NUM> is transparent and can be operably supported by the support plate <NUM>. Further, the window <NUM> and the support plate <NUM> can be integrally formed such that one or more windows <NUM> are integrated within the support plate <NUM>. Likewise, the foil <NUM> is also transparent or includes portions that are transparent. As used herein, the terms "transparent" and "radiotransparent" refer to a material that allows at least a portion of radiant energy of a selected wavelength to pass through. For example, the radiant energy that passes through the window <NUM> and the foil <NUM> can be in the ultraviolet spectrum, the infrared spectrum, the visible spectrum, or any other practicable radiant energy. Non-limiting examples of transparent materials include polymers, glass, and crystalline minerals, such as sapphire or quartz.

The foil <NUM> extends between the feed module <NUM> and the take-up module <NUM> and defines a "build surface" <NUM>, which is shown as being planar, but could alternatively be arcuate (depending on the shape of the support plate <NUM>). In some instances, the build surface <NUM> may be defined by the foil <NUM> and be positioned to face the stage <NUM> with the window <NUM> on an opposing side of the foil <NUM> from the stage <NUM>. For purposes of convenient description, the build surface <NUM> may be considered to be oriented parallel to an X-Y plane of the apparatus <NUM>, and a direction perpendicular to the X-Y plane is denoted as a Z-axis direction (X, Y, and Z being three mutually perpendicular directions). As used herein, the X-axis refers to the machine direction along the length of the foil <NUM>. As used herein, the Y-axis refers to the transverse direction across the width of the foil <NUM> and generally perpendicular to the machine direction. As used herein, the Z-axis refers to the stage direction that can be defined as the direction of movement of the stage <NUM> relative to the window <NUM>.

The build surface <NUM> may be configured to be "non-stick," that is, resistant to adhesion of a cured resin R. The non-stick properties may be embodied by a combination of variables such as the chemistry of the foil <NUM>, its surface finish, and/or applied coatings. For instance, a permanent or semi-permanent non-stick coating may be applied. One non-limiting example of a suitable coating is polytetrafluoroethylene ("PTFE"). In some examples, all or a portion of the build surface <NUM> may incorporate a controlled roughness or surface texture (e.g. protrusions, dimples, grooves, ridges, etc.) with nonstick properties. Additionally, or alternatively, the foil <NUM> may be made in whole or in part from an oxygen-permeable material.

For reference purposes, an area or volume immediately surrounding the location of the foil <NUM> and the window <NUM> or transparent portion defined by the support plate <NUM> may be defined as a "build zone," labeled <NUM>.

In some instances, a material depositor <NUM> may be positioned along the foil <NUM> and can include a reservoir. The material depositor <NUM> may be any device or combination of devices that is operable to apply a layer of resin R on the foil <NUM>. The material depositor <NUM> may optionally include a device or combination of devices to define a height of the resin R on the foil <NUM> and/or to level the resin R on the foil <NUM>. Nonlimiting examples of suitable material deposition devices include chutes, hoppers, pumps, spray nozzles, spray bars, or printheads (e.g. inkjets). In some examples, a doctor blade may be used to control the thickness of resin R applied to the foil <NUM>, as the foil <NUM> passes the material depositor <NUM>.

The resin R includes any radiant-energy curable material, which is capable of adhering or binding together the filler (if used) in the cured state. As used herein, the term "radiant-energy curable" refers to any material which solidifies or partially solidifies in response to the application of radiant energy of a particular frequency and energy level. For example, the resin R may include a photopolymer resin containing photo-initiator compounds functioning to trigger a polymerization reaction, causing the resin R to change from a liquid (or powdered) state to a solid state. Alternatively, the resin R may include a material that contains a solvent that may be evaporated out by the application of radiant energy. The uncured resin R may be provided in solid (e.g. granular) or liquid form, including a paste or slurry.

Furthermore, the resin R can have a relatively high viscosity fluid that will not "slump" or run off during the build process. The composition of the resin R may be selected as desired to suit a particular application. Mixtures of different compositions may be used. The resin R may be selected to have the ability to out-gas or burn off during further processing, such as a sintering process.

The resin R may incorporate a filler. The filler may be pre-mixed with resin R, then loaded into the material depositor <NUM>. The filler includes particles, which are conventionally defined as "a very small bit of matter. " The filler may include any material that is chemically and physically compatible with the selected resin R. The particles may be regular or irregular in shape, may be uniform or non-uniform in size, and may have variable aspect ratios. For example, the particles may take the form of powder, of small spheres or granules, or may be shaped like small rods or fibers.

The composition of the filler, including its chemistry and microstructure, may be selected as desired to suit a particular application. For example, the filler may be metallic, ceramic, polymeric, and/or organic. Other examples of potential fillers include diamond, silicon, and graphite. Mixtures of different compositions may be used. In some examples, the filler composition may be selected for its electrical or electromagnetic properties, e.g. it may specifically be an electrical insulator, a dielectric material, an electrical conductor, and/or magnetic.

The filler may be "fusible," meaning it is capable of consolidation into a mass upon via application of sufficient energy. For example, fusibility is a characteristic of many available powders including but not limited to polymeric, ceramic, glass, and metallic. The proportion of filler to resin R may be selected to suit a particular application. Generally, any amount of filler may be used so long as the combined material is capable of flowing and being leveled, and there is sufficient resin R to hold together the particles of the filler in the cured state.

The stage <NUM> is a structure defining a planar surface <NUM>, which is capable of being oriented parallel to the build surface <NUM> or the X-Y plane. Various devices may be provided for moving the stage <NUM> relative to the window <NUM> parallel to the Z-axis direction. For example, as illustrated in <FIG>, the movement may be provided through a vertical actuator <NUM> connected between the stage <NUM> and a static support <NUM>, with the understanding that devices such as ballscrew electric actuators, linear electric actuators, pneumatic cylinders, hydraulic cylinders, delta drives, or any other practicable device may additionally or alternatively be used for this purpose. In addition to, or as an alternative to, making the stage <NUM> movable, the foil <NUM> could be movable parallel to the Z-axis direction.

The radiant energy device <NUM> may be configured as any device or combination of devices operable to generate and project radiant energy on the resin R in a suitable pattern and with a suitable energy level and other operating characteristics to cure the resin R during the build process. For example, as shown in <FIG>, the radiant energy device <NUM> may include a projector <NUM>, which may generally refer to any device operable to generate a radiant energy patterned image of suitable energy level and other operating characteristics to cure the resin R. As used herein, the term "patterned image" refers to a projection of radiant energy comprising an array of one or more individual pixels. Non-limiting examples of patterned imaged devices include a DLP projector or another digital micromirror device, a two-dimensional array of LEDs, a two-dimensional array of lasers, and/or optically addressed light valves. In the illustrated example, the projector <NUM> includes a radiant energy source <NUM> such as a UV lamp, an image forming apparatus <NUM> operable to receive a source beam <NUM> from the radiant energy source <NUM> and generate a patterned image <NUM> to be projected onto the surface of the resin R, and optionally focusing optics <NUM>, such as one or more lenses.

The image forming apparatus <NUM> may include one or more mirrors, prisms, and/or lenses and is provided with suitable actuators, and arranged so that the source beam <NUM> from the radiant energy source <NUM> can be transformed into a pixelated image in an X-Y plane coincident with the surface of the resin R. In the illustrated example, the image forming apparatus <NUM> may be a digital micro-mirror device.

The projector <NUM> may incorporate additional components, such as actuators, mirrors, etc. configured to selectively move the image forming apparatus <NUM> or other part of the projector <NUM> with the effect of rastering or shifting the location of the patterned image on the build surface <NUM>. Stated another way, the patterned image may be moved away from a nominal or starting location.

In addition to other types of radiant energy devices <NUM>, the radiant energy device <NUM> may include a "scanned beam apparatus" used herein to refer generally to any device operable to generate a radiant energy beam of suitable energy level and other operating characteristics to cure the resin R and to scan the beam over the surface of the resin R in a desired pattern. For example, the scanned beam apparatus can include a radiant energy source <NUM> and a beam steering apparatus. The radiant energy source <NUM> may include any device operable to generate a beam of suitable power and other operating characteristics to cure the resin R. Non-limiting examples of suitable radiant energy sources <NUM> include lasers or electron beam guns.

The apparatus <NUM> may be operably coupled with a computing system <NUM>. The computing system <NUM> in <FIG> is a generalized representation of the hardware and software that may be implemented to control the operation of the apparatus <NUM>, including some or all of the stage <NUM>, the radiant energy device <NUM>, actuators, and the various parts of the apparatus <NUM> described herein. The computing system <NUM> may be embodied, for example, by software running on one or more processors embodied in one or more devices such as a programmable logic controller ("PLC") or a microcomputer. Such processors may be coupled to process sensors and operating components, for example, through wired or wireless connections. The same processor or processors may be used to retrieve and analyze sensor data, for statistical analysis, and for feedback control. Numerous aspects of the apparatus <NUM> may be subject to closed-loop control.

Optionally, the components of the apparatus <NUM> may be surrounded by a housing <NUM>, which may be used to provide a shielding or inert gas (e.g., a "process gas") atmosphere using gas ports <NUM>. Optionally, pressure within the housing could be maintained at a desired level greater than or less than atmospheric. Optionally, the housing could be temperature and/or humidity controlled. Optionally, ventilation of the housing could be controlled based on factors such as a time interval, temperature, humidity, and/or chemical species concentration. In some embodiments, the housing <NUM> can be maintained at a pressure that is different than an atmospheric pressure.

Referring to <FIG> and <FIG>, a schematic drawings of an accumulator that may be positioned within the manufacturing apparatus <NUM> are illustrated. In general, the accumulator may be positioned between two components along the foil path of the apparatus. For example, as illustrated in <FIG>, the accumulator <NUM> may be positioned between a pair of build zones <NUM>. Additionally, or alternatively, as illustrated in <FIG>, the accumulator <NUM> may be positioned between a build zone <NUM> and a resin reclamation system <NUM>. In some embodiments, the reclamation system <NUM> may be configured to remove at least a portion of uncured resin R that remains on the foil <NUM> after the foil <NUM> is removed from a build zone <NUM>. For example, the reclamation system <NUM> may include a wiper assembly, a blade assembly, and/or any other removal assembly and a reservoir for collecting the resin R that is removed from the foil <NUM>.

With further reference to <FIG> and <FIG>, in some embodiments, the accumulator <NUM> may be configured to retain an intermediate portion <NUM> of the foil <NUM>. For instance, a first portion <NUM> of the foil <NUM> upstream of the accumulator <NUM> and a second portion <NUM> of the foil <NUM> downstream of the accumulator <NUM>. By retaining the intermediate portion <NUM> of the foil <NUM>, the first and second portions <NUM>, <NUM> of the foil <NUM> may be moved independently of one another. For example, the first portion <NUM> of the foil <NUM> upstream of the accumulator <NUM> can move at a first speed while the second portion <NUM> of the foil <NUM> downstream of the accumulator <NUM> can move at a second speed. Additionally, or alternatively, the first portion <NUM> of the foil <NUM> upstream of the accumulator <NUM> can move intermittently while the second portion <NUM> of the foil <NUM> downstream of the accumulator <NUM> can move continuously. Additionally, or alternatively, the first portion <NUM> of the foil <NUM> upstream of the accumulator <NUM> can move continuously while the second portion <NUM> of the foil <NUM> downstream of the accumulator <NUM> can move intermittently. Further, the first portion <NUM> and/or the second portion <NUM> of the foil <NUM> may move in any other manner independent of one another without departing from the teachings provided herein.

As illustrated in <FIG> and <FIG>, the accumulator <NUM> may include an accumulator housing <NUM> defining a cavity <NUM> therein. The cavity <NUM> is configured to house the intermediate portion <NUM> of the foil <NUM>. However, it will be appreciated that in other embodiments, the accumulator may be free of a housing and/or a cavity. Further, in some embodiments, the accumulator may be in line with the foil path.

The intermediate portion <NUM> of the foil <NUM> may be of variable length during operation of the apparatus <NUM>. For example, in some instances, a first length of foil <NUM> may be within the cavity <NUM> during a first period of time during operation of the apparatus <NUM> and a second length of foil <NUM> may be within the cavity <NUM> during a second period of time after the first period of time. The second length of foil <NUM> may be equal to, less than, or greater than the first length based on the operations of the apparatus <NUM>.

With further reference to <FIG> and <FIG>, one or more guides <NUM>, <NUM> may be operably coupled with the accumulator housing <NUM> to assist or direct the foil <NUM> from a position upstream of the cavity <NUM> into the cavity <NUM> and/or downstream of the cavity <NUM> out of the cavity <NUM>. For instance, in the embodiments illustrated in <FIG> and <FIG>, the one or more guides <NUM>, <NUM> may be configured as first and second rollers <NUM>, <NUM> positioned on opposing sides of the cavity <NUM>.

The accumulator <NUM> includes a material retention assembly <NUM> to retain the foil <NUM>. For example, the material retention assembly <NUM> may include one or more retaining rollers <NUM> within the cavity <NUM> defined by the accumulator <NUM>. The one or more retaining rollers <NUM> may be configured to maintain the foil <NUM> in a within the cavity <NUM>. For instance, the retaining roller <NUM> may be configured to pull the foil <NUM> towards a bottom portion <NUM> of the cavity <NUM> by providing a force on the first side of the foil <NUM>. The retaining roller <NUM> may be configured to move at least partially within the cavity <NUM> and/or may be stationary within a predefined location within the cavity <NUM>. In some instances, the one or more retaining rollers <NUM> may be configured as a dimpled roller or the like to provide a tension across the width of the foil while minimizing contact with the foil <NUM> and/or any resin R disposed on the foil <NUM>. Additionally or alternatively, the one or more retaining rollers <NUM> may be configured to contact an outer perimeter of the foil <NUM> that is outside of the resin R such that the one or more retaining rollers <NUM> remains free of resin R as the foil <NUM> moves from the feed module <NUM> towards the take-up module <NUM>.

As illustrated, an actuator <NUM> may be operably coupled with the one or more retaining rollers <NUM> and configured to alter a position of the one or more retaining rollers <NUM>. The actuator may also be communicatively coupled with the computing system <NUM>.

As illustrated <FIG>, the material retention assembly <NUM> includes one or more pneumatic actuation zones <NUM> with each pneumatic actuation zone <NUM> configured to selectively interact with the foil <NUM> by producing a force on a surface of the foil <NUM> opposite the resin R.

The one or more pneumatic actuation zones <NUM> may apply a negative pressure on a first surface of the foil <NUM> that is opposite to the resin, or a second side of the foil <NUM>, to produce a suction or vacuum on the foil <NUM>. The negative pressure may retain the foil <NUM> in a desired position within the cavity <NUM>. As used herein, a "negative" pressure is any pressure that is less than an ambient pressure proximate to one or more pneumatic actuation zones <NUM> such that fluid may be drawn into the one or more pneumatic actuation zones <NUM>. Conversely, a "positive" pressure is any pressure that is greater than an ambient pressure proximate to one or more pneumatic actuation zones <NUM> such that fluid may be exhausted from the one or more pneumatic actuation zones <NUM>. Further, a "neutral" pressure is any pressure that is generally equal to an ambient pressure proximate to one or more pneumatic actuation zones <NUM>.

In some examples, the pneumatic actuation zones <NUM> may be fluidly coupled with a pneumatic assembly <NUM> through various hoses and one or more ports. The pneumatic assembly <NUM> may include any device capable of providing a vacuum/suction and/or pushing a fluid, such as air or a process gas (e.g., nitrogen or argon), through the one or more pneumatic actuation zones <NUM>. For instance, the pneumatic assembly <NUM> may include a pressurized fluid source that includes a compressor and/or a blower. The pneumatic assembly <NUM> may additionally or alternatively include any assembly capable of altering a pressure, such as a venturi vacuum pump. In some embodiments, one or more valves and/or switches may be coupled with the pneumatic assembly <NUM> and the one or more pneumatic actuation zones <NUM>. The one or more valves and/or switches are configured to regulate a pressure to each of the one or more pneumatic actuation zones <NUM>.

Referring to <FIG>, an enhanced view of area V of <FIG> illustrates an exemplary pneumatic actuation zone <NUM> that includes one or more apertures <NUM> of any size and shape for interacting with the foil <NUM>. For instance, the apertures <NUM> may be any number and combination of holes, slits, or other geometric shapes defined by any component of the additive manufacturing apparatus <NUM>, such as an inner surface of the housing. Additionally, or alternatively, the apertures <NUM> may be defined by a portion of the housing being formed from a porous material, or through any other assembly in which a fluid may be moved from a first side of the inner surface of the housing to a second side of the inner surface of the housing to interact with the foil <NUM>.

In some examples, the pneumatic actuation zone <NUM> may be defined by a plenum <NUM>. The plenum <NUM> may be of any size and may be similar or varied from the shape of any remaining plenums <NUM>. In some instances, a gasket may be positioned about a rim of the plenum <NUM>. As illustrated in <FIG>, in various embodiments, the one or more pneumatic actuation zones <NUM> of the material retention assembly <NUM> may be configured to interact with a first side of the foil <NUM> while the resin R is provided on a second, opposing side of the foil <NUM>.

Additionally, or alternatively, as illustrated in <FIG> and <FIG>, the accumulator <NUM> may include a support <NUM> that is configured to interact with the first side of the foil <NUM>. In some instances, the support <NUM> may include a pneumatic zone such that the first side of the foil <NUM> may be drawn towards the support <NUM> when a negative pressure is experienced through the support <NUM>.

In various embodiments, the retaining roller <NUM> and/or the support <NUM> of <FIG> and <FIG> may be operably coupled with a track assembly <NUM> that guides movement of the retaining roller <NUM> and/or the support <NUM> along the cavity <NUM>. The track assembly <NUM> may be of any configuration such as a guide and/or a swing arm and may utilize electronic control, mechanical control (spring(s)), pneumatic control, or any other control for directing the retaining roller <NUM> and/or the support <NUM> within the cavity <NUM>. Moreover, it will be appreciated that the track assembly <NUM> may be of any geometric shape and may have generally linear and/or curved portions.

With further reference to <FIG>, in several embodiments, a detection system <NUM> may be positioned within the accumulator <NUM>. The detection system <NUM> may be capable of providing data related to one or more conditions of the accumulator <NUM> and/or the foil <NUM> within the accumulator <NUM>. Based on the received data, the computing system <NUM> may determine a length of the foil <NUM> within the accumulator <NUM>, a distance from a lowermost portion of the foil <NUM> above a bottom portion <NUM> of the cavity <NUM>, an amount of foil <NUM> within the cavity <NUM> of the accumulator <NUM>, a change in the amount of foil <NUM> within the accumulator <NUM>, a speed at which the foil <NUM> enters and/or exits the cavity <NUM>, and/or any other information. Based on the conditions of the accumulator <NUM> and/or the foil <NUM> within the accumulator <NUM>, various portions of the foil <NUM> may be moved at different speeds relative to one another and/or a first portion <NUM> of the foil <NUM> may move intermittently (e.g., stopped for at least a portion of time during a predefined time period) while a second portion <NUM> of the foil <NUM> may be configured to move continuously during the predefined time period.

In some embodiments, the detection system <NUM> may include a sensor <NUM>, which may be positioned within the accumulator <NUM> and/or otherwise configured to detect data related to one or more conditions of the accumulator <NUM> and/or the foil <NUM> within the accumulator <NUM>. The sensor <NUM> may be embodied as one or more imagers or any other vision-based device. The sensor <NUM> may additionally and/or alternatively be configured as any other practicable proximity sensor, such as, but not limited to, an ultrasonic sensor, a radar sensor, a LIDAR sensor, or the like.

Additionally, or alternatively, in various embodiments, the detection system <NUM> may include one or more bypass holes <NUM> defined by the accumulator housing <NUM> along the cavity <NUM> of the accumulator <NUM>. In various embodiments, such as the embodiment illustrated in <FIG>, the bypass holes <NUM> may be defined within a cavity plate <NUM> that extends rearwardly and/or forwardly of the cavity <NUM>. The accumulator <NUM> may include both forwardly and rearwardly cavity plates <NUM> that extend along opposing open ends of the cavity <NUM>. Additionally or alternatively, as illustrated in <FIG>, in some embodiments, the one or more bypass holes <NUM> may be defined by the housing <NUM> and extend along the housing <NUM> within the cavity <NUM>. The bypass holes <NUM> may form a passive valve system in which the position of the foil <NUM> within the cavity <NUM> may be determined by detecting which holes <NUM> have a vacuum pulled thereon and which holes <NUM> do not have a flow. For example, when the foil <NUM> does not extend beyond a respective bypass hole <NUM>, a negative pressure will be provided on the bypass hole <NUM>. Conversely, when the foil <NUM> extends beyond a respective bypass hole <NUM>, the negative pressure detected by the bypass hole <NUM> may be reduce and/or no longer present. As such, based on which bypass holes <NUM> have a negative pressure thereon, the location of the foil <NUM> within the cavity <NUM> may be generally provided to the computing system <NUM> as data.

Referring to <FIG>, the one or more guides <NUM>, <NUM> of the accumulator <NUM> includes a first guide <NUM> on a first side of the cavity <NUM> and/or a second guide <NUM> on a second side of the cavity <NUM> to assist or direct the foil <NUM> from a position upstream of the cavity <NUM> into the cavity <NUM> and/or downstream of the cavity <NUM> out of the cavity <NUM>. Each of the first and second guides <NUM>, <NUM> may be configured to move the foil <NUM> in a predetermined direction and/or retain the foil <NUM> in a predetermined position. The one or more guides <NUM>, <NUM> can be configured to control the speed and direction of the foil <NUM> into and/or out of the accumulator <NUM>. By way of example and not limitation, the one or more guides <NUM>, <NUM> can include motors, actuators, feedback sensors, and/or controls for driving the one or more guides <NUM>, <NUM> in such a manner so as to maintain the foil <NUM> tensioned between the feedback module and the take-up module <NUM>.

In some embodiments, the first guide <NUM> may be configured to drive movement of the foil <NUM> from the feed module <NUM> to the accumulator <NUM> and the feed module <NUM> may be configured to control the tension of the foil <NUM> between the feed module <NUM> and the first guide <NUM>. Further, the take-up module <NUM> may be configured to drive a movement of the foil <NUM> from the accumulator <NUM> to the take-up module <NUM> and the second guide <NUM> may be configured to control the tension of the foil <NUM> between the take-up module <NUM> and the second guide <NUM>.

In various embodiments, such as the embodiment illustrated in <FIG>, the first and second guides <NUM>, <NUM> may each be configured as a pair of rollers 82A, 82B, 84A, 84B positioned on opposing first and second sides of the foil <NUM>. Each respective pair of rollers 82A, 82B, 84A, 84B may contain a first roller 82A, 84A positioned on a first side of the foil <NUM> and a second roller 82B, 84B positioned on a second, opposing side of the foil <NUM>. Each of the first and second rollers 82A, 82B, 84A, 84B contacts the foil <NUM> such that the foil <NUM> may be pinched or otherwise retained between each set of the first and second rollers 82A, 82B, 84A, 84B. In some instances, the first rollers 82A, 84A may be configured as a dimpled roller or the like to provide a tension across the width of the foil while minimizing contact with the foil <NUM> and/or any resin R disposed on the foil <NUM>. Additionally, or alternatively, the first rollers 82A, 84A may be configured to contact an outer perimeter of the foil <NUM> that is outside of the resin R such that the roller 82A, 84A remains free of resin R as the foil <NUM> moves from the feed module <NUM> towards the take-up module <NUM>.

Additionally, or alternatively, as illustrated in <FIG> and <FIG>, the first and/or the second guide <NUM> may include a guide pneumatic device <NUM> that is configured to draw the foil <NUM> towards the guide pneumatic device <NUM> when a negative pressure is provided through the guide pneumatic device <NUM>. In instances in which the first guide <NUM> and/or the second guide <NUM> include the guide pneumatic device <NUM>, the respective first guide <NUM> and/or the second guide <NUM> may include a single roller positioned below the bottom side of the foil <NUM>.

Referring to <FIG> and <FIG>, in several embodiments, the first guide <NUM> and/or the second guide <NUM> may be configured as a pneumatic plate <NUM>. The suction plate may be integrated into the accumulator housing <NUM>, the support plate <NUM>, and/or any other component of the apparatus <NUM>. Like the guide pneumatic device <NUM>, the bottom side of the foil <NUM> may be drawn towards the pneumatic plate <NUM> when a negative pressure is provided through the pneumatic plate <NUM>. Additionally, or alternatively, a positive pressure may be provided through the pneumatic plate <NUM> to blow the bottom side of the foil <NUM> away from the accumulator housing <NUM> or any other component of the apparatus <NUM>.

Referring now to <FIG>, a schematic drawing is provided illustrating a plurality of stages <NUM> in parallel positioned between the material depositor <NUM> and the accumulator <NUM> in accordance with an exemplary embodiment of the present disclosure. Each of the plurality of stages <NUM> may define an independent build zone <NUM>. As provided herein, the accumulator <NUM> may include one or more guides <NUM>, <NUM> that includes a first guide <NUM> on a first side of the cavity <NUM> and a second guide <NUM> on an opposing, second side of the cavity <NUM>. Furthermore, the first guide <NUM> may drive the foil <NUM> from the feed module <NUM> through the plurality of build zones <NUM> and the feed module <NUM> may maintain a tension of the foil <NUM> between the feed module <NUM> and the first guide <NUM>. In addition, the first guide <NUM> may also push the foil <NUM> therethrough and into the cavity <NUM> of the accumulator <NUM>. The take-up module <NUM> may be used to drive the foil <NUM> downstream of the accumulator <NUM> and/or pull foil <NUM> from the accumulator <NUM> while the second guide <NUM> controls a tension of the foil <NUM> downstream of the second guide <NUM>.

Referring to <FIG> and <FIG>, schematic drawings are provided illustrating various exemplary embodiments that include multiple accumulators <NUM>. The multiple accumulators <NUM> may be positioned upstream and downstream of a build zone <NUM>, as exemplarily illustrated in <FIG>. Additionally, or alternatively, as illustrated in <FIG>, the accumulators <NUM> may be respectively positioned such that each of the build zones <NUM> and/or other assemblies are upstream and/or downstream of both of the accumulators <NUM>.

In some embodiments, such as the exemplary embodiment illustrated in <FIG>, the material depositor <NUM> may be positioned between the feed module <NUM> and a first accumulator 64A. In some instances, a first portion <NUM> of the foil <NUM> may be defined between the feed module <NUM> and the first accumulator 64A. One or more build zones <NUM> may be positioned downstream of the first accumulator 64A and upstream of a second accumulator 64B. A second portion <NUM> of the foil <NUM> may be defined between the first and the second accumulators 64A, 64B. In addition, a take-up module <NUM> may be downstream of the second accumulator 64B and a third portion <NUM> of foil <NUM> may be defined between the second accumulator 64B and the take-up module <NUM>. Further, in some instances, a resin reclamation system <NUM> and/or another unit <NUM> may be positioned between the second accumulator 64B and the take-up module <NUM> and/or at any position between the feed module and the take-up module. For example, the unit <NUM> may accomplish any process that interacts with the foil <NUM>, such as quality a process (e.g., image analysis of the foil <NUM>).

In various embodiments, the first portion <NUM> of the foil <NUM> may move between the feed module <NUM> and the first accumulator 64A at a first speed, while the second portion <NUM> of the foil <NUM> may move between the first and second accumulators 64A, 64B at a second speed, and the third portion <NUM> of the foil <NUM> may move between the second accumulator 64B and the take-up module <NUM> at a third speed. In some instances, at least one of the first speed, the second speed, and/or the third speed may be different from any of the remaining speeds. Accordingly, the resin R may be deposited on the foil <NUM> upstream of the first accumulator 64A while the first portion <NUM> of foil <NUM> moves at a first speed. Independently, the second portion <NUM> of the foil <NUM> may be operated through one or more build zones <NUM> at a second speed. Likewise, the third portion <NUM> of the foil <NUM> may have at least a portion of the resin R remaining thereon that is removed through the reclamation system <NUM> with the third portion <NUM> of the foil <NUM> moving at the third speed.

Additionally, or alternatively, the first portion <NUM>, the second portion <NUM>, and/or third portion <NUM> of the foil <NUM> may each independently move in a continuous manner and/or intermittently over various time periods. For example, the first portion <NUM> of the foil <NUM> may move in a generally continuously move while the second portion <NUM> and/or the third portion <NUM> of the foil <NUM> move intermittently. Likewise, the second portion <NUM> of the foil <NUM> may move continuously while the first portion <NUM> and/or the third portion <NUM> of the foil <NUM> move intermittently. Further, the third portion <NUM> of the foil <NUM> may move continuously while the first portion <NUM> and/or the second portion <NUM> of the foil <NUM> move intermittently.

It will be appreciated that in addition to the same or different speeds of the various portions of the foil <NUM> discussed herein, the foil <NUM> within any of the one or more accumulators 64A, 64B may move at a speed that is different or equal to any other to the other portions of the foil <NUM>. Moreover, it will be appreciated that the foil <NUM> in any one or more of the accumulators 64A, 64B may be stationary for various time periods. The intermittent movement of the foil <NUM> may be independent of any of the portions of the foil <NUM> that are external to the one or more accumulators 64A, 64B of the apparatus <NUM>.

Referring to <FIG>, a schematic drawing is provided of an exemplary embodiment in which a pair of accumulators 64A, 64B are each positioned downstream of a plurality of build zones <NUM> and upstream of a post-curing process, such as a resin reclamation process that may be accomplished through the reclamation system <NUM>. As illustrated, one of the first accumulator 64A or the second accumulator 64B may be timed to the cycle while the second of the first accumulator 64A or the second accumulator 64B may function as a buffer in case the first accumulator 64A and/or another portion of the apparatus <NUM> has temporary disturbances. As such, in some embodiments, the foil <NUM> may pass above the cavity <NUM> of the second accumulator 64B and into the cavity <NUM> of the first accumulator 64A when the first accumulator 64A is functioning correctly. Additionally, or alternatively, in instances when the computing system determines that the foil <NUM> is close to the bottom portion <NUM> of the first accumulator 64A, the second accumulator 64B may accept the foil <NUM> into the cavity <NUM> thereof.

Now that the construction and configuration of the additive manufacturing apparatus having one or more accumulators have been described according to various examples of the present subject matter, a method <NUM> for operating an additive manufacturing apparatus is provided. The method <NUM> can be used to operate the additive manufacturing apparatus and the one or more accumulators, or any other suitable additive manufacturing apparatus having any type and configuration of positioning assembly. It should be appreciated that the example method <NUM> is discussed herein only to describe example aspects of the present subject matter and is not intended to be limiting.

Referring now to <FIG>, the method <NUM> includes, at step <NUM>, moving a first portion of a foil a first distance during a defined time period, wherein the first portion of the foil is positioned upstream of an accumulator. As the first portion of the foil is moved the first distance during the defined time period, one or more operations may be performed that incorporate the first portion of the foil. Moreover, at step <NUM>, the method can include continuously translating the first portion of the foil the first distance during the defined time period at a generally constant speed. At step <NUM>, when the first portion of the foil is being translated, the method can include depositing a layer of an uncured resin onto the foil. As provided herein, a material depositor may be positioned along the foil and is operable to apply the layer of uncured resin over the foil.

Additionally or alternatively, the method at step <NUM>, can include intermittently translating the first portion the foil the first distance during the defined time period. At step <NUM>, when the first portion of the foil is generally stationary, either at the end of the defined time period and/or during the time period, the method can include maintaining a position of the first portion of the foil having the resin deposited thereon within a build zone.

At step <NUM>, when the first portion of the foil is generally stationary, the method can include moving the stage to contact the resin on the second side of the foil, and, at step <NUM>, the method can include curing at least a portion of the uncured layer of resin to create a newly cured layer of the component through the use of a radiant energy device.

During the operation of steps <NUM>-<NUM>, the method, at step <NUM>, can include moving a second portion of the foil a second distance during the defined time period, wherein the second portion of the foil is positioned downstream of the accumulator. In various embodiments, the second distance is different from the first distance. At step <NUM>, the method can include interacting with the second portion of the foil during the defined time period. At step <NUM>, interacting with the second portion of the foil during the defined time period comprises translating the second portion of the foil through a reclamation system. Additionally or alternatively, at step <NUM>, interacting with the second portion of the foil during the defined time period comprises performing a quality measurement on the second portion of the foil.

In order to allow for the first portion and the second portion of the foil to be moved different distances and/or for one to be moved while the other portion is stationary, an accumulator is positioned between the first and second portions of the foil. As such, at step <NUM>, the method includes maintaining an intermediate portion of the foil between the first and second portions within the accumulator. As provided herein, the accumulator may define a cavity and the intermediate portion of the foil may be disposed within the cavity. In some instances, the method, at step <NUM>, can include maintaining the intermediate portion of the foil between the first and second portions within the accumulator by producing a negative pressure on a surface of the intermediate portion of the foil.

The method, at step <NUM>, can further include, determining a length of foil within the cavity, which may be accomplished through the use of one or more sensors. In some embodiments, at step <NUM>, the method can further include adjusting the movement of the first portion and/or the second portion of the foil based on the length of the foil within the cavity. For example, in some embodiments, the foil length may be maintained within a predefined range during operation. If the length of the foil within the cavity is below a lower threshold of the range, the first portion of the foil may be translated at an increased speed and/or a quicker interval. Additionally, or alternatively, the second portion of the foil may be translated at a reduced speed and/or a slower interval. Similarly, if the length of the foil within the cavity is above an upper threshold of the range, the first portion of the foil may be translated at a reduced speed and/or a slower interval. Additionally, or alternatively, the second portion of the foil may be translated at an increased speed and/or a quicker interval. In various embodiments, a priority may be determined in which the speed and/or interval at which one of the first or second portion is changed may occur before the other of the first or second portion of the foil is changed. For example, the movement of the second portion of the foil may be altered prior to alteration of the first portion of the foil.

It will be appreciated that both the first distance and/or the second distance may be any length from zero meters to any defined length within the defined time period. In instances in which the first distance and/or the second distance is zero, the first portion of the foil and/or the second portion of the foil is generally stationary during the defined time period.

<FIG> depicts certain components of computing system <NUM> according to example embodiments of the present disclosure. The computing system <NUM> can include one or more computing device(s) 58A which may be used to implement the method <NUM> such as described herein. The computing device(s) 58A can include one or more processor(s) 58B and one or more memory device(s) 58C. The one or more processor(s) 58B can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field-programmable gate array (FPGA), logic device, one or more central processing units (CPUs), graphics processing units (GPUs) (e.g., dedicated to efficiently rendering images), processing units performing other specialized calculations, etc. The memory device(s) 58C can include one or more non-transitory computer-readable storage medium(s), such as RAM, ROM, EEPROM, EPROM, flash memory devices, magnetic disks, etc., and/or combinations thereof.

The memory device(s) 58C can include one or more computer-readable media and can store information accessible by the one or more processor(s) 58B, including instructions 58D that can be executed by the one or more processor(s) 58B. The instructions 58D may include one or more steps of the method <NUM> described above, such as to execute operations of the material retention assembly <NUM> of the additive manufacturing apparatus <NUM> described above. For instance, the memory device(s) 58C can store instructions 58D for running one or more software applications, displaying a user interface, receiving user input, processing user input, etc. In some implementations, the instructions 58D can be executed by the one or more processor(s) 58B to cause the one or more processor(s) 58B to perform operations, e.g., such as one or more portions of methods described herein. The instructions 58D can be software written in any suitable programming language or can be implemented in hardware. Additionally, and/or alternatively, the instructions 58D can be executed in logically and/or virtually separate threads on processor(s) 58B.

The one or more memory device(s) 58C can also store data 58E that can be retrieved, manipulated, created, or stored by the one or more processor(s) 58B. The data 58E can include, for instance, data to facilitate performance of the method <NUM> described herein. The data 58E can be stored in one or more database(s). The one or more database(s) can be connected to computing system <NUM> by a high bandwidth LAN or WAN or can also be connected to the computing system through network(s) (not shown). The one or more database(s) can be split up so that they are located in multiple locales. In some implementations, the data 58E can be received from another device.

The computing device(s) 58A can also include a communication module or interface 58F used to communicate with one or more other component(s) of computing system <NUM> or the additive manufacturing apparatus <NUM> over the network(s). The communication interface 58F can include any suitable components for interfacing with one or more network(s), including, for example, transmitters, receivers, ports, controllers, antennas, or other suitable components.

Claim 1:
An additive manufacturing apparatus (<NUM>) comprising:
a feed module (<NUM>) configured to operably couple with a first end portion of a foil (<NUM>);
a take-up module (<NUM>) configured to operably couple with a second end portion of a foil (<NUM>);
at least one stage (<NUM>) configured to hold one or more cured layers of a resin (R) that form a component (<NUM>);
a radiant energy device (<NUM>) positioned opposite to the at least one stage (<NUM>), the radiant energy device (<NUM>) operable to generate and project radiant energy in a predetermined pattern;
an actuator (<NUM>) configured to change a relative position of the at least one stage (<NUM>) and the foil (<NUM>); and
an accumulator (<NUM>) positioned between the feed module (<NUM>) and the take-up module (<NUM>), the accumulator (<NUM>) configured to retain an intermediate portion of the foil (<NUM>) to allow a first portion of the foil (<NUM>) upstream of the accumulator (<NUM>) to move at a first speed and a second portion of the foil (<NUM>) downstream of the accumulator (<NUM>) to move at a second speed during a defined time period;
characterized in that it further comprises:
a material retention assembly (<NUM>) within the accumulator (<NUM>);
wherein the material retention assembly (<NUM>) includes a pneumatic actuation zone (<NUM>) that is configured to selectively interact with the foil (<NUM>) by producing a force on a first side of the foil (<NUM>), the first side of the foil (<NUM>) being opposite the resin (R).