Patent ID: 12194686

DETAILED DESCRIPTION

The following detailed description and appended drawings describe and illustrate various embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical.

“A” and “an” as used herein indicate “at least one” of the item is present; a plurality of such items may be present, when possible. As used herein, “substantially” means “to a considerable degree,” “largely,” or “proximately” as a person skilled in the art in view of the instant disclosure would understand the term. Spatially relative terms, such as “front,” “back,” “inner,” “outer,” “bottom,” “top,” “horizontal,” “vertical,” “upper,” “lower,” “side,” “up,” “down,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

FIG.1illustrates a filament extrusion process100. The process100includes a hopper102in communication with an inlet of an extruder103. It is understood that the extruder103can be any convention extruder, as desired, such as a single or double screw extruder. An outlet of the extruder103is in communication with a die or discharge component105. The die105is configured to discharge a material101from the extruder103in a desired size and shape. The die105is in communication with a cooling apparatus106. The cooling apparatus106can be any cooling or heat transfer apparatus, as desired, capable of cooling the material101in a desired time and to a desired temperature. A cooling bath108in in communication with the cooling apparatus106in an upstream direction and a filament spool109in a downstream direction with respect to a direction of flow of the material101through the process100. The filament spool109is configured to wind a continuous spool of the material101thereon.

During operation of the process100, the material101is added to the hopper102. The material101may be in the form of pellets or small pieces or have other shapes and configurations as desired. The material101may comprise a polymer or other material having desired properties for use as a filament of a 3D printing process. The extruder103receives the material101, melts the material101by applying heat, and forces the melted material104through the die105. After the melted material104exits the die105, it is cooled by the cooling apparatus106to a desired temperature and solidifies to form a solid filament107. The cooling apparatus106may use air or other fluid as a heat exchange medium, as desired, to remove heat from the melted material104. The cooling apparatus106may provide a volume of a cooling fluid for the melted material104to pass through. The cooling fluid may be constantly added to and removed from the cooling apparatus106in order to maintain a set point temperature for the cooling fluid in the cooling apparatus106. The cooling fluid may be water, an aqueous solution, or other conventional cooling fluids as desired.

FIG.1also shows the cooling bath108. Whereas the cooling apparatus106may rapidly cool the melted material104, the cooling bath108may further cool the solid filament107at a lower temperature reduction rate. The hot, melted material104may be cooled to a temperature below a melting point of the material101forming the solid filament107. For example, the hot, melted material104may be cooled to a temperature between 65° F. and 150° F. The desired, cool temperature may be achieved by the cooling apparatus106alone or by a combination of the cooling apparatus106and the cooling bath108. A residence time that the solid filament107spends in the cooling bath108may be longer than a residence time that the solid filament107spends in the cooling apparatus106. The cooling bath108may comprise a heat exchange fluid or other cooling medium as desired. The heat exchange fluid may be water, an aqueous solution, or other heat exchange fluid, for example.

Warm (heated) or ambient air may be blown across the solid filament107to dry excess heat exchange fluid from the filament107. Alternatively, an infrared (IR) oven may be used to dry excess heat exchange fluid from the filament107. The solid filament107may be wound onto the filament spool109and the filament spool109may then be used in an FFF printer to print a 3D printed object. The filament spool109may be marked with an indicium that is unique to that spool.

A diameter, ovality, and other properties or characteristics of the filament107may be measured by a sensing device, a sensor, or an instrument110. As a non-limiting example, the instrument110may be a laser micrometer. The laser micrometer includes an emitter or emitters that scan a measurement field with a laser or lasers. When an object is present in the measurement field, the object's shadow is cast into a receiver which can use this information to determine the diameter, the ovality, and other properties and dimensions of the filament107. Production data may be received by the instrument110and uploaded and stored, along with a unique indicium of the spool109(such as a barcode, a QR code or an RFID, for example) in a database111stored on a storage device such as a hard drive, the internet, or other conventional storage devices. Optionally, data may be stored on an RFID to eliminate the need for an end user to connect to the internet. Production data may include one or more of the following: filament diameter, filament ovality, filament tolerance, filament extrusion temperature during filament production, filament cooling temperature during filament production, filament cooling rate during production (after being extruded), filament extrusion die size, filament production rate (amount of filament forced through an extrusion die per unit of time), the number of sensors that were used to measure filament diameter and/or ovality, the type and/or model number of the sensor(s) (or instrument) used to measure filament diameter and/or ovality, the geographical location of filament production, and the origin of raw materials that were used to produce a filament. In general, any data that is captured in the manufacturing process may be stored and used to enhance a 3D print. A filament's properties may be cataloged as a function of filament location within a spool of filament. For example, the filament may be segmented by length and each segment may have a stored physical property. A 3D printer could make adjustments to print settings (for example, extrusion ratio or extrusion temperature) based on the properties of the filament segment being printed at a given time. In this case, a 3D printer would know, for example, that the first foot of filament has diameter X (or some other measured property), the second foot of filament has diameter Y, and the third foot of filament has diameter Z. The unit of length could be smaller (for example, every inch of filament could have a corresponding diameter or other property) to provide more granularity and more frequent 3D printer compensations. Conversely, the unit of length could be larger (for example, every 2 feet of filament could have a corresponding diameter or other physical property) to reduce the amount of data that is stored. The database111may be stored on the storage device for data retrieval and/or further processing. Thus, physical properties of the filament107on the spool109are measured and stored for later use.

In the prior art, filament manufacturers have been able to reduce filament diameter tolerances from ±0.07 mm to ±0.05 mm, with present targets of ±0.03 mm and even ±0.02 mm. Without compensating for the tolerances of the filament107for the specific spool being printed, there will always be a deviation in printed dimensions when the tolerance for the diameter of the filament107that is greater than zero.

FIG.2illustrates an additive manufacturing system200. The additive manufacturing system200can be a fused filament fabrication (FFF) system as shown inFIG.2. However, other additive manufacturing systems200can be used without departing from the scope of the invention. The additive manufacturing system includes a filament spool201disposed on a spindle. The filament spool201includes a filament202wound thereon, wherein the filament is fed to a print head203. A nozzle204including a nozzle tip205is formed on the print head203. The additive manufacturing system200further includes a build plate207configured to support a 3D printed object208formed from liquefied or partially liquefied filament.

In operation, the filament spool201of the additive manufacturing system200stores the filament202thereon in a wound manner. The filament202moves from the filament spool201to the print head203via hobs or gears (not shown). The print head203includes a heated section (not shown) that liquefies the filament202being fed thereto so that the filament202is liquefied or partially liquefied when it exits the nozzle204at the nozzle tip205. The liquefied or partially liquefied filament206is initially deposited onto the build plate207. It is understood that multiple spools and filaments may be fed to the print head for depositing on the build plate207if desired. The print head203moves about in the x, y, and z directions the liquefied or partially liquefied filament206is deposited onto the build plate. It is further understood that the build plate can be moved in the x, y, and z directions and the print head203may be stationary without departing from the scope of the invention. Upon cooling, the liquefied or partially liquefied filament206deposited on the build plate207solidifies and becomes part of the 3D printed object208.

Variability in an amount of the liquefied or partially liquefied filament206deposited contributes to irregularities in the 3D printed object208. For a given length of the filament202moving through the print head203that is deposited as the liquefied or partially liquefied filament206, the total volume of the liquefied or partially liquefied filament206deposited is a function of the diameter of the filament202. For example, if the diameter of the filament202is larger than a target diameter, the volume of the liquefied or partially liquefied filament206deposited will be larger than the targeted volume. Conversely, if the diameter of the filament202is smaller than a desired target, the volume of the liquefied or partially liquefied filament206deposited will be less than the targeted volume. The mass and dimensions of the 3D printed object208from these two examples will therefore vary because of the variability in the diameter of the filament202. In order to achieve consistency among the 3D printed objects208, a constant diameter of the filament202is important. One way to achieve the consistent diameter of the filament202is to tightly control the diameter of the filament202during the extrusion process, while discarding any filament that is out of a specified tolerance of the diameter of the filament202. The embodiments disclosed herein correct or compensate for a variation in the diameter of the filament202during the 3D printing process. If the diameter of the filament202being fed to the 3D printer is larger than the target diameter, the 3D printer will change print parameters to account for the larger diameter. For example, a feed rate for the filament202may be reduced for a given speed of the print head203so that the target volume of the liquefied or partially liquefied filament206is deposited for a given length of filament deposition. Conversely, if the diameter of the filament202being fed to the 3D printer is smaller than the target diameter, the 3D printer will increase the feed rate of the filament202for a given print head speed so that the target volume of the liquefied or partially liquefied filament206is deposited for a given length of filament deposition.

As shown inFIG.2, data stored for a given spool of filament202may be retrieved from the database111created during the process100, and used to modify print parameters such as filament feed rate. By way of example, the feed rate of the filament202may be increased or decreased to compensate for the diameter of the filament202being fed. In this way, the deposited volume of the filament202is more consistent and is less dependent on consistency of the filament202during production of the filament202. The physical properties of the filament202of the spool201are measured during production of the filament202and stored on database111, which could be an internet website or a hard drive of a computer, for example. After transferring or purchasing the spool201of the filament202, an end-user scans the barcode, QR code, or RFID on the spool201. The barcode, QR code, or RFID links to the website or hard drive that holds production data for the exact spool201being used. The end-user's 3D printer receives the data and modifies print parameters to make adjustments as necessary. For example, the 3D printer's extrusion ratio or feed rate may be adjusted based on the diameter of the filament202.

The filament spool201may comprise an RFID, QR code, or barcode that can be scanned by the printer to identify the filament spool201and to look up production data for the filament spool201. The production data may comprise minimum diameter and maximum diameter for the filament202of a given filament spool202. However, other production data can be provided and used without departing from the scope of the invention. The 3D printer may use the data to change an extrusion ratio of the print head203. The extrusion ratio is defined here as a ratio of the feed rate of the filament202(length of filament dispensed from the nozzle per unit time) to a speed of the print head203(distance traveled per unit time). If the extrusion rate is set for an assumed filament diameter and the actual filament diameter is less or more than the assumed filament diameter, too little or too much filament will be extruded which results in a 3D printed part that is lacking material (as evidenced by gaps or areas that are too thin, for example) or that has too much material (as evidenced by areas that are too thick or areas that contain excess material, for example). Adjusting the extrusion ratio based on the actual diameter of the filament202that is being fed to the 3D printer optimizes the quality of a 3D printed object and reduces dimensional tolerances, compared to adjusting the extrusion ratio based on the average filament diameter for a batch of multiple spools.

Compensating for variations in the filament2024on a per-spool basis is especially beneficial for filament production processes that produce filament with a consistent offset from the target diameter for a given spool. For example,FIG.3shows a possible scenario where a filament production process is targeting a filament diameter of 1.75 mm with a tolerance of ±0.05 mm. As shown inFIG.3, the actual filament diameter being produced (for one spool) is continuously between 1.70 mm and 1.75 mm (hovers around 1.725 mm). The filament depicted inFIG.3would typically be marketed and sold as a 1.75 mm±0.05 mm filament. However, when the production data for that spool is collected during production, stored in a retrievable location, retrieved by a 3D printer, and used by the 3D printer to make print adjustments to compensate for the actual filament diameter, a better-quality print will result. Effectively, the 3D printed part (printed in a printer that adjusts print properties such as extrusion rate, based on filament production data for a given spool) would have the quality of a 3D printed part that was printed with a ±0.025 mm tolerance filament.

FIG.4depicts an exemplary computing and control system1100for use in association with the herein described systems and methods. The computing and control system1100is capable of executing software such as an operating system (OS) and/or one or more computing applications/algorithms1190such as applications applying the print plan, monitoring, process controls, process monitoring, and process modifications discussed herein, and may execute such applications1190using the data such as materials and process-related data which may be stored in a storage database1115locally or remotely.

More particularly, the operation of an exemplary computing system1100is controlled primarily by computer readable instructions such as instructions stored in a computer readable storage medium, such as a hard disk drive (HDD)1115, an optical disk (not shown) such as a CD or DVD, a solid state drive (not shown) such as a USB “thumb drive,” or the like. Such instructions may be executed within a central processing unit (CPU)1110to cause computing system1100to perform the operations discussed herein. In many known computer servers, workstations, personal computers, and the like, the CPU1110is implemented in an integrated circuit called a processor.

It is appreciated that, although the exemplary computing system1100is shown to comprise a single CPU1110, such description is merely illustrative, as the computing system1100may comprise a plurality of the CPUs1110. Additionally, the computing system1100may exploit the resources of remote CPUs (not shown), for example, through a communications network1470or some other data communications means.

In operation, the CPU1110obtains, decodes, and executes instructions from a computer readable storage medium such as the HDD1115. Such instructions may be included in software such as an operating system (OS), executable programs such as the aforementioned correlation applications, and the like. Information such as computer instructions and other computer readable data is transferred between components of computing system1100via the system's main data-transfer path. The data may include a physical characteristic lookup table for the spool, for example. The main data-transfer path may use a system bus architecture1105, although other computer architectures (not shown) can be used such as architectures using serializers and deserializers and crossbar switches to communicate data between devices over serial communication paths. The system bus1105may include data lines for sending data, address lines for sending addresses, and control lines for sending interrupts and for operating the system bus1105. Some busses provide bus arbitration that regulates access to the bus by extension cards, controllers, and the CPU1110.

Memory devices coupled to the system bus1105may include random access memory (RAM)1125and/or read only memory (ROM)1130. Such memories include circuitry that allows information to be stored and retrieved. The ROMs1130generally contain stored data that cannot be modified. The data stored in RAM1125can be read or changed by the CPU1110or other hardware devices. Access to the RAM1125and/or the ROM1130may be controlled by a memory controller1120. The memory controller1120may provide an address translation function that translates virtual addresses into physical addresses as instructions are executed. The memory controller1120may also provide a memory protection function that isolates processes within the system and isolates system processes from user processes. Thus, a program running in user mode may normally access only memory mapped by its own process virtual address space; in such instances, the program cannot access memory within another process' virtual address space unless memory sharing between the processes has been set up.

In addition, the computing system1100may contain a peripheral communications bus1135, which communicates instructions from the CPU1110to, and/or receiving data from, peripherals, such as peripherals printer1140, keyboard1145, and mouse1150, and may include any combination of printers, keyboards, and/or the sensors discussed herein throughout. An example of a peripheral bus is the Peripheral Component Interconnect (PCI) bus.

A display1160, which is controlled by a display controller1155, may be used to display visual output and/or other presentations generated by or at the request of the computing system1100, such as in the form of a graphical user interface (GUI), responsive to operation of the aforementioned computing program(s). Such visual output may include text, graphics, animated graphics, and/or video, for example. The display1160may be implemented with a CRT-based video display, an LCD or LED-based display, a gas plasma-based flat-panel display, a touch-panel display, or the like. The display controller1155includes electronic components required to generate a video signal that is sent to the display1160.

Further, the computing system1100may contain a network adapter1165which may be used to couple the computing system1100to an external communication network1170, which may include or provide access to the Internet, an intranet, an extranet, or the like. The communications network1470may provide user access for the computing system1100with means of communicating and transferring software and information electronically. Additionally, the communications network1470may provide for distributed processing, which involves several computers and the sharing of workloads or cooperative efforts in performing a task. It is appreciated that the network connections shown are exemplary and other means of establishing communications links between computing system1100and remote users may be used.

A network adaptor1165may communicate to and from the network1170using any available wired or wireless technologies. Such technologies may include, by way of non-limiting example, cellular, Wi-Fi, Bluetooth, infrared, or the like.

It is appreciated that exemplary computing system1100is merely illustrative of a computing environment in which the herein described systems and methods may operate, and does not limit the implementation of the herein described systems and methods in computing environments having differing components and configurations. That is to say, the inventive concepts described herein may be implemented in various computing environments using various components and configurations.

From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.