Patent ID: 12202210

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings and pictures, which show the exemplary embodiment by way of illustration and its best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that logical and mechanical changes may be made without departing from the spirit and scope of the invention. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not limited to the order presented. Moreover, any of the functions or steps may be outsourced to or performed by one or more third parties. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component may include a singular embodiment.

In general, the present disclosure relates to a system and method for providing 3D object manufacturing. The disclosed embodiments each involve the application of a new layer of material, such as a photopolymer, a powder or any other type of material that is capable of changing phase or solidifying under irradiation. To better understand the present invention,FIGS.1A-1Cshow side, front and perspective views of a centrifugal additive manufacturing system100attached to a mobile cart that allows for system100to be transported to various locations. It should be appreciated that centrifugal manufacturing system100can instead be attached to a fixed location. A fixed location can be more beneficial in situations where increased stability is desired and/or the system is scaled up in size to a point where easy relocation is no longer feasible.

FIG.1Ashows a first side view of system100. System100includes a drum102within which system100creates new parts. Motor104is located beneath drum102and configured to rotate drum102. Motor104can be a direct drive motor attached directly to a base of drum102. In some embodiments, drum102and motor104can be attached to cart106by a motor mounting plate108and a suspension system110that allows for a limited amount of lateral movement of drum102and motor104during operation of system100. Allowance of a small amount of lateral movement can be helpful in preventing unwanted vibrational excursions when rotating drum102at high rotational velocities. Suspension system110includes a series of springs and rails that biases a position of drum102and motor104toward a central location but as mentioned above also allows for up to 5 mm of lateral movement to help dissipate undesired vibrational excursions of drum102resulting from addition, subtraction or movement of materials within drum102.

A material deliver channel112extends through and along a longitudinal axis of motor104and into a base of drum102. A series of bushings further extend a length of material delivery channel112below motor104and to a rotary union114, which includes one or more ports for supplying material into material delivery channel112. Rotary union114includes a stationary lower assembly for attachment to one or more hoses for supplying material into material delivery channel112and an upper assembly coupled to the lower assembly by a bearing that allows for rotation of the upper assembly relative to the lower assembly. This configuration allows material delivery channel112to rotate with drum102so that material being supplied to drum102through material delivery channel112shares the same inertial reference frame as drum102prior to arriving and being deposited within drum102. This helps to improve an evenness of the distribution of material being added into the base of drum102.

FIG.1Aalso shows a location of a light source module116elevated above drum102. As depicted, light source module116is affixed to cart106by a vertical movement assembly118that includes a motor responsible for moving light source module116vertically into and out of a light source module opening in drum102during operation of system100. An electrical panel120is attached to a rear side of cart106and configured to power the various components of system100.FIG.1Aalso shows a location of tank122, which is responsible for holding material that is introduced into drum102and in some embodiments also responsible for regulating a temperature of the material so that when used its properties are as expected. In some embodiments, the material held by tank122can be a photopolymer material that solidifies when irradiated by a light source. Also depicted is a filter124that can optionally be utilized to remove any impurities in the material held within tank122prior to the material being introduced into drum102.

FIG.1Bshows a front view of system100that illustrates a location of pumping mechanism126relative to other components of system100. In particular, pumping mechanism126is linked by one or more conduits128to other components and designed to utilize those conduits to move material from tank122, through filter124and into rotary union114and ultimately up material delivery channel112, through motor104and into drum102. Pumping mechanism126can be designed to periodically deliver precise amounts of material into drum102to avoid instances of a waste of material or an overly thick or thin layer of material that negatively affects accuracy or stability of a resulting part. Exemplary layer thicknesses generally vary from between 10 microns to 50 microns but can also vary more widely between a range of 5 microns and 250 microns depending on the intended purpose of the work to be done by the system. In some embodiments, pumping mechanism126can take the form of a motorized syringe style delivery mechanism allowing a precise cylindrical displacement of working material to be added to provide material into drum102in a precise amount and at a precise rate. In other embodiments, other types of pumping mechanisms can be used such as metering pumps, plunger pumps or diaphragm pumps. In some embodiments, system100can include multiple pumping mechanisms to inject different types of fluids into and out of drum102. For example, cleaning and/or curing fluids can also be routed through material delivery channel112.

FIG.1Cshows a perspective view of system100and a view of suspension system110, which includes orthogonal bearings130and132that accommodate small movements in the X and Y directions. Motor mounting plate108is also shown fastened in multiple locations to suspension system110in a manner such that motor mounting plate is prevented from rotating during operation of system100, thereby allowing motor104to drive operation apply rotation to drum102.

FIG.2shows a perspective view of a select group of components of system100that illustrates a cross-section of portions of drum102, motor104, rotary union114and material delivery channel112. In particular, rotary union114is shown with lower assembly202and upper assembly204that is configured to rotate with respect to lower assembly202. Lower assembly202is shown with two ports for attaching conduits configured to deliver material stored in tank122or cleaning or curing solution stored in other containers of system100into material delivery channel112. Once the liquid passes through rotary union114it enters the portion of material delivery channel formed by bushing elements206that connect rotary union114to motor112.

FIG.2also shows how drum102includes a sloped interior-facing bottom surface leading up to a curved sidewall210. An angle of the interior facing bottom surface could be sloped at an angle of between 10 and 25 degrees. In one particular embodiment, a sloped angle of 18 degrees can be used. The sloped bottom surface reduces the speed material hits sidewall210and thereby prevents the material from splashing and thereby spreading more turbulently when hitting sidewall210at higher speeds. In some embodiments, a conformal sleeve can be arranged along curved sidewall210allowing for parts formed against sidewall210to be easily removed from drum102following part formation. Furthermore, the conformal sleeve can be formed of flexible material such as sheet metal that when flattened pulls away from the curved rearward geometry of formed parts to easily separate the parts without doing unintentional damage.

FIG.2also shows how drum102can be formed of a main body212and a lid214. Lid214includes an opening216sized to receive light source module116. Opening216can be sized slightly larger than a diameter of light source module116such that drum102is able to shift laterally, as allowed by suspension110, without resulting in any collisions between light source module116and drum102.FIG.2also shows pump mechanism126mounted on multiple springs218that help prevent any vibrations generated by operation of pump mechanism126from disrupting consistent rotation of drum102during operation of system100.

FIG.3Ashows a cross-sectional side view of drum102, motor104and light source module116inserted within drum102. Light source module116is inserted within drum102during normal operation of system100. Light source module includes a lens assembly302and a light source assembly304. Lens assembly302is configured to move closer to or farther away from light source assembly304in order to focus light306generated by laser diodes308arranged along light source assembly304on curved sidewall210. While only a single laser diode is shown emitting light308it should be appreciated that all 20 laser diodes depicted inFIG.3could be concurrently activated in the event a particularly large part is being built within drum102. Since light source module116does not rotate with drum102, laser light emitted by light source module116scans across curved surface at the speed of the rotation of drum102. While a light source module116is shown that includes 20 laser diodes306, it should be appreciate that a fewer or larger number of laser diodes and associated lenses is also possible. In some embodiments, light source module116can translate vertically in order to allow the light generated by the laser diodes to solidify portions of material arranged on sidewall210that is located vertically between laser diodes308. In some embodiments, laser diodes and lenses can be packed together at an interval allowing coverage of an entirety of material arranged on sidewall210during operation of system100. In the present embodiment, each laser diode can be responsible for covering a vertical length of about 10-15 mm.

In addition to carrying laser diodes, light source module can also include LEDs designed to apply a curing process to the finished parts within drum102. In some specific embodiment, the LEDs can be incorporated into a first side of light source assembly304opposite from a second side of light source assembly304that carries laser diodes. By placing optical windows on opposing sides of light source module116, light source module116can assist with both solidification of the working material and with curing of the solidified working material.

Timing of the actuation of light source module116is important to the proper formation of parts within drum102. Furthermore at the speeds that drum102travels, conventional methods of determining with high precision a rotational position of drum102is quite challenging. The presently disclosed system100incorporates a sensor known as a laser encoder to determine a current rotational position of drum102. However due to the rapid rotational speeds commonly reached by drum102(e.g. greater than 1500 rpm), utilizing a standard, off the shelf laser encoder would lack the accuracy needed to fire the various laser diodes that drive light source module at precisely the right times to get a desired level of part accuracy. This is a result of a standard laser encoder not being capable of including a large enough number of tic marks it relies upon to tell current rotational position. For this reason, a processor being utilized to fire the light generating components of light source module116at the proper times can interpolate a current rotational position of drum102by estimating a rotational position of drum102utilizing instantaneous drum rotational speeds. In this way, instead of reporting the final tic mark detected by the laser encoder a position of drum102between tic marks can be determined and used to help determine a more precise time at which light source module116is set to operate each of its light generating components or laser diodes in the present exemplary embodiment.

FIG.3Aalso shows a flow of material310delivered through material delivery channel112up sloped bottom surface208of drum102as it approaches sidewall210. In some embodiments, solidification operations are paused as the material for forming the next layer in drum102begins flowing up side wall210. In some embodiments, it can take between 0.5 and 2 seconds for the material to travel from pump mechanism126to a base portion of sidewall210and then about 0.2 to 0.5 seconds to make its way up the sidewall of drum102. Time taken will depend on the height of the walls of drum102, the amount of material supplied and the speed at which the material is pumped into drum102. Thickness of the layers of material arranged on curved side wall210can be driven by a speed of rotation of drum102. Generally, by varying the rotational speed and resulting amount of centrifugal forces applied to the liquid material on sidewall210, the designers have the benefit of specifying specific layer thicknesses when needed to achieve a specific part accuracy. This is achievable with the disclosed configurations since higher g-forces tend to compress the liquid material against sidewall210by a greater amount than lower g-forces.

FIG.3Aalso shows how a portion of material delivery channel112running through motor104is defined by tubing312, which keeps any of the material from getting lodged within mechanical components of motor104as it moves from bushing elements206to drum102. While tubing is used in this particular configuration it should be appreciated that a motor could also be used with a liquid resistance channel instead of the tubing shown inFIG.3A. As depicted, tubing312connects one end of bushing elements206to a base portion of drum102.FIG.3Bshows how material310moves up bottom wall208. During this time and as depicted illumination from laser diodes308is ceased. This offers a large benefit over previously designed systems that generally require use of a material deposition arm or module taking up space within the working space, resulting in high complexities and limitations that can slow operation of the system.

FIG.3Cshows a final resting position for material310prior to it stabilizing in place to form a flat layer on curved sidewall210due to the influence of centrifugal force caused by rotation of drum102.FIG.3Calso shows how multiple laser diodes308can be active at once. Furthermore, as additional layers of material get built up on sidewall210a position of lens assembly302shifts position to keep a focus of laser diodes308on the latest layer of material added. In some embodiments, light source module116can be calibrated without fixing any minor positioning anomalies with the multiple laser diodes and associated optics. Instead a location of the light can be observed and then operation of the system can be adjusted so that lasers that are out of alignment adjust their timing so that the right material is solidified at the right time. In some embodiments, light source assembly can be tested at the beginning of each operation so that proper calibration can be confirmed and/or updated to get optimal results. The calibration causes the plans for creating the part to be adjusted for any lasers that are determined to be out of alignment so that the lasers activate at the proper time.

FIG.3D-3Eshow exploded and cross-sectional views of a specific implementation of rotary union114. In particular, lower assembly202can be referred to as a rotary union body and upper assembly204can be referred to as a rotary union spindle. Upper assembly204is able to spin relative to lower assembly202without generating much friction on account of ball bearings352. This is much more efficient than most current solutions that rely on two rubbing rings/surfaces, which would generate a much larger amount of heat than desired. In some embodiments, the surfaces in contact with the ball bearings can be polished to further reduce the amount of heat/wear generated during part operation. A seal354is positioned near a base of upper assembly204and prevents the ingress of liquids into the portion of rotary union114in which ball bearings352resides. A retaining ring356can be used to keep ball bearings352seated between upper assembly204and lower assembly202. When rotary union is being used to add material into material delivery channel112, the material enters rotary union114at the location indicated by arrow358and exits rotary union114at the location indicated by arrow360.

FIG.4Ashows a top down cross-sectional view of multiple parts402being prepared in a drum404of a centrifugal additive manufacturing system in accordance with the described embodiments. Parts402are formed by solidifying the material added into drum404over the course of part formation.FIG.4Ashows how drum404looks before spinning down so that unsolidified material406remains affixed to sidewalls of drum404. In addition to parts402, flow stoppers408can be formed between parts. Flow stoppers408are configured to prevent waves of unsolidified material from being formed during rotation of drum404and causing undesirable rotational motion likely to negatively affect production of parts and/or diminish the lifespan of the machine. In some embodiments, instead of using the additive manufacturing system for forming the flow stoppers408, pre-made flow stoppers or fins can be attached to drum404by either slotting into a main body of drum404or by attaching to a lid of drum404and then being lowered into an interior volume defined by drum404. It should be noted that by scaling up the size of drum404can result in a less severe curvature and fewer issues creating parts with flat surfaces. In some embodiments an orientation of the part within drum404can be established to minimize issues in which many surfaces require multiple layers to form.

FIG.4Aalso demonstrates how the curvature of the powder layers can differ from the geometry of parts402that have linear surfaces. One result is that unlike slower conventional flat additive manufacturing system a flat surface facing the longitudinal axis of drum404is constructed using more than one layer due to the mismatch between the layer geometry and the part geometry. In these instances there can be some amount of surface discontinuity as a result when layers have a larger thickness. One advantage to the fixed laser configuration described herein is that power output of the laser can be modulated to produce a smoother surfaces in situation where a single surface needs to be produced over the course of multiple layers. For example, a processor can be configured to modulate the output power of each laser diode of the light source module between at least three different power states (e.g., off, full power and partial power). In some embodiments, previously mentioned fine tuning of determination of rotational positioning allows partial power passes to be applied with high accuracy to smooth areas that might otherwise show obvious scan lines between layers. Conventional additive manufacturing systems utilize a fixed power laser and so must just accept any rough part surfaces resulting from these mismatches in part and material layer geometry.

FIG.4Bshows an alternative embodiment in which fins410are attached to an interior-facing surface of lid412. Fins410can be attached via one or more fasteners that extend through openings in lid412and into adapters414configured to secure fins410to lid412. In this way fins410act as flow stoppers or flow inhibitors removing the need to have the additive manufacturing system create flow stoppers.

Once parts are formed the system can be further configured to evacuate unsolidified material406through openings410that allow the unsolidified material406to exit through material delivery channel112(seeFIGS.2-3C). Following evacuation of unsolidified material406, alcohol can be pumped into and back out of drum404again using the material delivery channel112in order to clean parts402of any excess unsolidified material406. Following the cleaning step material delivery channel112can again be utilized to introduce curing agent into drum404. In addition to carrying a set of laser diodes for solidifying the working material within the drum, the light source module can also include a set of LEDs having an output suited for curing finished parts following the washing process. Manufacturers can save substantial time and expense since the described embodiments do not require the finished parts to be taken to a variety of different locations to undergo the washing and curing steps.

FIG.5shows an alternative embodiment in which a drum502is rotated at high speeds while metal powder mixed with a gas such as nitrogen is blown into drum502at a 30 to 60 degree angle depending on the dimensions of drum502using a gas blower504. By angling the gas-borne metal powder into drum502the metal powder imbued gas forms a vortex within drum502and then centrifugal force exerted on the metal powder keeps the metal powder affixed to interior facing curved walls of drum502while a light source assembly504is lowered into drum502in a similar way as to how it is placed in the previously described drum and light source assemblies. Metal powder generally takes a more powerful type of laser such as, e.g., a YAG laser. In this embodiment, a YAG laser can be positioned outside drum502and its light channeled into light source assembly504using multiple fiber optic cables such that the output of the single powerful YAG laser can be divided to have a similar but more powerful configuration that the light source module described with regards to system100. Each fiber optic cable can be incorporated into cable bundle508and attached to an optical pathway that can include focusing elements within light source assembly504. An acousto-optical modulator can be arranged along each of the fiber optic cables and configured to turn off and on the laser output being split into each of the fiber-optic cables, to correspond to requirements for building parts within drum502.

FIG.6shows an exemplary plot600showing the importance of various parameters to the success of operation of the present additive manufacturing embodiments. In particular, it shows how laser power must be modulated in order to get a desired depth of part material solidification. Solidifying too deep or too shallowly can result in part inaccuracies. This graph also demonstrates how a partial power laser could be configured to perform the type of layer blending operation described above as it allows for a different depth of solidification to be achieved thereby creating a blending layer in places.

FIG.7shows an exemplary electronic device700usable with the described embodiments. In particular, processor700represents one or more processors responsible for operation of a system such as system100. Processor700can be responsible for collecting information from multiple sensors, such as sensors702and704. In some embodiments, sensor702can take the form of a laser indexer utilized to measure a rotational position of a drum of a system. As discussed previously, processor700can be configured to use the position information provided by the laser indexer, calculate a speed and/or acceleration of the drum at any point in time to accurately estimate with high accuracy a position of the drum at any point in time. Processor700can then take the position, speed and/or acceleration information and use it to adjust operation of motor706utilized to spin the drum and/or modulate output of light source module708. In some embodiments, processor700may want to avoid requiring too strict an operating speed as additions of materials into the drum can result in changes in to the drum inertia and rotational energy that can make maintaining a strict band of rotational velocity overly difficult. As long as the rotational position sensor accurately tracks speed, processor700can command changes to operation of light source module704in order to achieve highly accurate part accuracies.

FIG.8shows a timeline illustrating operation of an exemplary additive manufacturing device compatible with the embodiments depicted inFIGS.1A-4B. At802and at time t=0, an array of lasers of a light source module begins scanning a material layer arranged upon a sidewall of a drum in accordance with the previously described embodiments. At804and also at time t=0, a fixed amount of temperature controlled working material is prepared for injecting into a material delivery channel of the additive manufacturing system. In embodiments where the pump mechanism takes the form of a syringe style delivery system, the syringe begins to be filled at time t=0 with the fixed amount of working material in preparation for injecting. Other pump mechanisms can include a small holding tank where the fixed amount of working material is stored while waiting for injection into the system. At806, the pump mechanism filling completes while the laser array continues scanning the working material previously added to the drum.

At808, the pump mechanism begins moving the fixed amount of working material into the material delivery channel where it begins making its way toward the drum. At808and time t=D, the working material after entering the drum reaches a base of an interior-facing curved surface of the drum. At814and also at time t=D the light source module ends the scanning operation and the working material starts to climb up the curved interior sidewall. At816and time t=D+propagation, the new layer of working material evenly coats the interior-facing surface of the drum and the process returns to802and804where laser scanning and pump filling begin again

It should be appreciated that while some specific examples of working materials have been given, such as photopolymers that other types of materials are also possible. For example, in some embodiments, the working material can take the form of a slurry incorporating metal powder that allows for the formation of a metal part using the embodiments shown inFIGS.1A-4B.

The previous description of the disclosed examples is provided to enable any person of ordinary skill in the art to make or use the disclosed methods and apparatus. Various modifications to these examples will be readily apparent to those skilled in the art, and the principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosed method and apparatus. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosed apparatus and methods. The steps of the method or algorithm may also be performed in an alternate order from those provided in the examples.