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This application claims the benefit of U.S. Provisional Application No. 61/719,874 filed on Oct. 29, 2012, the entire content of which is hereby incorporated by reference.
The invention generally relates to an extruder assembly, and more specifically an extruder assembly including a quick-release extruder for a device and system for three-dimensional fabrication.
Three-dimensional printing is a process for making a three-dimensional solid object of virtually any shape from a digital model. Three-dimensional printing is achieved using an additive process, where successive layers of build material are laid down in different shapes. The build material may be in the form of a filament, and may include, for example, acrylonitrile butadiene styrene (ABS), high-density polyethylene (HDPL), polylactic acid (PLA), or any other suitable plastic, thermoplastic, or other material that can usefully be extruded to form a three-dimensional object. The filament may be extruded using an extruder, which may include a chamber, an opening at an extruder tip, and a motor to push the filament into the chamber and through the opening in the extruder tip.
Access to extruders is typically fairly limited. In most three-dimensional printing systems, a user must remove the entire extruder to perform maintenance. To remove the extruder typically requires specific tools and can be a time-consuming process. Also, loading, unloading, and replacement of the filament are difficult and time-consuming because of the lack of easy access to the components of the extruder assembly.
There is a need for a quick-release extruder that can allow a user access to the components of the extruder assembly for, e.g., maintenance, loading, unloading, and replacement of the filament.
A bearing that provides contact force to engage a filament with a drive gear has a movable axis that can be controllably moved toward and away from the drive gear in order to engage and disengage the filament. A bearing is spring-biased toward the drive gear, and a bistable lever mechanism is provided with a first stable position in which the bearing is engaged with a filament and a second stable position in which the bearing is disengaged from the filament. By providing a mechanism that locks in both positions, loading and unloading of filament can be facilitated.
In one aspect there is disclosed herein an extruder assembly including a drive gear shaped and sized to drive a filament; a bearing having a freely rotating contact surface, the bearing positioned to support the filament against the drive gear with the freely rotating contact surface, where an axis of the bearing is substantially parallel to an axis of the drive gear and where the axis of the bearing is movable toward and away from the axis of the drive gear; a spring configured to bias a position of the axis of the bearing relative to the axis of the drive gear; and a lever positioned to apply a counterforce to the bias of the spring, thereby securing the bearing in a position to apply a constant contact force to the filament by the bearing and the drive gear.
The extruder assembly may include an extruder as described herein, which may include an input opening aligned to a feedpath. The build material, which may be in the form of a filament, may travel through the opening and thus into the feedpath, which continues into a chamber of the extruder that is shaped and sized to pass the filament along the feedpath. The filament may then travel through an orifice of the extruder, which may discharge the build material during an extrusion.
The filament may be driven by a drive gear, which may include a number of teeth. The teeth of the drive gear may be positioned to engage the filament before the input opening in the feedpath. Specifically, the filament may be driven into the teeth of the drive gear with enough force to deform the build material, and thus the teeth of the drive gear may grip the filament in this manner. The spring or biasing member may provide the force required to deform the build material into the teeth of the drive gear. The drive gear may then rotate (or otherwise provide movement) such that the teeth drive the filament along the feed path, into the input opening of the extruder, through the chamber, and out of the orifice. It will be apparent that the drive gear may engage the build material in an alternate manner such that the drive gear is configured to drive the build material through the extruder. The drive gear may include a motor that may be integral with the drive gear or coupled to the drive gear such that the motor rotates (or otherwise drives) the drive gear, which may then drive the filament.
A bearing may be positioned opposite the drive gear, and it may be located along the feedpath. The bearing may be biased by the spring toward the drive gear with a spring force such that the bearing presses the filament against the drive gear. The spring may be coupled to the bearing. The bearing may include a freely rotating contact surface that is able to provide a force against the drive gear and freely rotate with the drive gear without disengaging (when a force maintains the bearing in a position engaged with the drive gear). The spring may maintain a substantially constant contact force of the bearing against a length of the filament between the bearing and the drive gear in the absence of external forces. The bearing may include a smooth surface, and the bearing may be a low friction bearing. The axis of the bearing may be substantially parallel to the axis of the drive gear.
The extruder assembly may further include a lever that may extend from the extruder assembly. The lever may be configured to manually move the bearing (e.g., against the biasing force of the spring) away from the drive gear and/or away from the feedpath. Thus, the lever may be coupled to the bearing. Alternatively, the lever may be coupled to another mechanical element (or series of elements) and then coupled to the bearing, or the lever may be coupled to the drive gear. The lever may move the axis of the bearing away from the axis of the drive gear. The lever may include a pivot (or several pivots), and the spring may be coupled to the lever away from the pivot. The spring may provide a substantially constant force urging the lever into a first position or a second position. The extruder assembly may also include a locking mechanism to secure the lever in a position (which may be the first position, the second position, or another position) with the bearing moved away from and out of the feedpath and/or drive gear. The locking mechanism may also secure the lever in a position with the bearing moved toward and into the feedpath and/or drive gear. The locking mechanism may include a latch, a clamp, an electrical locking mechanism, a clip, a coupling, a dock, a hook, a pin, a snap, or the like.
The spring may include a coil spring, a compression spring, a leaf spring, or the like.
The extruder assembly may further include a heating element to liquefy a length of build material in the chamber of the extruder.
An extruder assembly may include a manual control extending from the extruder assembly to manually move the bearing against the spring force away from the feedpath. The manual control may include a lever, a knob, a slider, a plunger, a push button, a toggle, an actuator, a screw, a piston, and the like.
The lever may also be controlled electronically, and may be activated by a user utilizing a control system, or it may be automatically activated by a control system.
The foregoing and other objects, features and advantages of the invention will be apparent from the following description of particular embodiments thereof, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
FIG. 1 is a block diagram of a three-dimensional printer.
FIG. 2 is an exploded view of an extruder assembly.
FIG. 3 is a perspective view of an extruder assembly.
FIG. 4 is a left side view of an extruder assembly.
FIG. 5 is a front view of an extruder assembly.
FIG. 6 is a right side view of an extruder assembly.
FIG. 7 is a top view of an extruder assembly.
The embodiments will now be described more fully hereinafter with reference to the accompanying figures, in which preferred embodiments are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these illustrated embodiments are provided so that this disclosure will convey the scope of the invention to those skilled in the art.
All documents mentioned herein are hereby incorporated in their entirety by reference. References to items in the singular should be understood to include items in the plural, and vice versa, unless explicitly stated otherwise or clear from the text. Grammatical conjunctions are intended to express any and all disjunctive and conjunctive combinations of conjoined clauses, sentences, words, and the like, unless otherwise stated or clear from the context. Thus, the term “or” should generally be understood to mean “and/or” and so forth.
Recitation of ranges of values herein are not intended to be limiting, referring instead individually to any and all values falling within the range, unless otherwise indicated herein, and each separate value within such a range is incorporated into the specification as if it were individually recited herein. The word “about,” when accompanying a numerical value, is to be construed as indicating a deviation as would be appreciated by one of ordinary skill in the art to operate satisfactorily for an intended purpose. Ranges of values and/or numeric values are provided herein as examples only, and do not constitute a limitation on the scope of the described embodiments. The use of any and all examples, or exemplary language (“e.g.,” “such as,” or the like) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the embodiments. No language in the specification should be construed as indicating any unclaimed element as essential to the practice of the embodiments.
In the following description, it is understood that terms such as “first,” “second,” “above,” “below” and the like, are words of convenience and are not to be construed as limiting terms.
Described herein are devices, systems, and methods for using an extruder assembly including a quick-release extruder for a three-dimensional printer. It will be understood that while the exemplary embodiments herein emphasize an extruder assembly for a three-dimensional printer, the principles of the invention may be adapted to other fabrication processes. All such variations that can be adapted to use an extruder assembly as described herein are intended to fall within the scope of this disclosure.
FIG. 1 is a block diagram of a three-dimensional printer. In general, the printer 100 may include a build platform 102, a conveyor 104, an extruder 106, an x-y-z positioning assembly 108, and a controller 110 that cooperate to fabricate an object 112 within a working volume 114 of the printer 100.
The build platform 102 may include a surface 116 that is rigid and substantially planar. The surface 116 may support the conveyer 104 in order to provide a fixed, dimensionally and positionally stable platform on which to build the object 112.
The build platform 102 may include a thermal element 130 that controls the temperature of the build platform 102 through one or more active devices 132 such as resistive elements that convert electrical current into heat, Peltier effect devices that can create a heating or cooling affect, or any other thermoelectric heating and/or cooling devices. Thus the thermal element 130 may be a heating element that provides active heating to the build platform 102, a cooling element that provides active cooling to the build platform 102, or a combination of these. The heating element 130 may be coupled in a communicating relationship with the controller 110 in order for the controller 110 to controllably impart heat to or remove heat from the surface 116 of the build platform 102. Thus, the thermal element 130 may include an active cooling element positioned within or adjacent to the build platform 102 to controllably cool the build platform 102.
It will be understood that a variety of other techniques may be employed to control a temperature of the build platform 102. For example, the build platform 102 may use a gas cooling or gas heating device such as a vacuum chamber or the like in an interior thereof, which may be quickly pressurized to heat the build platform 102 or vacated to cool the build platform 102 as desired. As another example, a stream of heated or cooled gas may be applied directly to the build platform 102 before, during, and/or after a build process. Any device or combination of devices suitable for controlling a temperature of the build platform 102 may be adapted to use as the thermal element 130 described herein.
The conveyer 104 may be formed of a sheet 118 of material that moves in a path 120 through the working volume 114. Within the working volume 114, the path 120 may pass proximal to the surface 116 of the build platform 102—that is, resting directly on or otherwise supported by the surface 116—in order to provide a rigid, positionally stable working surface for a build. It will be understood that while the path 120 is depicted as a unidirectional arrow, the path 120 may be bidirectional, such that the conveyer 104 can move in either of two opposing directions through the working volume 114. It will also be understood that the path 120 may curve in any of a variety of ways, such as by looping underneath and around the build platform 102, over and/or under rollers, or around delivery and take up spools for the sheet 118 of material. Thus, while the path 120 may be generally (but not necessarily) uniform through the working volume 114, the conveyer 104 may move in any direction suitable for moving completed items from the working volume 114. The conveyor may include a motor or other similar drive mechanism (not shown) coupled to the controller 110 to control movement of the sheet 118 of material along the path 120. Various drive mechanisms are described in further detail below.
In general, the sheet 118 may be formed of a flexible material such as a mesh material, a polyamide, a polyethylene terephthalate (commercially available in bi-axial form as MYLAR), a polyimide film (commercially available as KAPTON), or any other suitably strong polymer or other material. The sheet 118 may have a thickness of about three to about seven thousandths of an inch, or any other thickness that permits the sheet 118 to follow the path 120 of the conveyer 104. For example, with sufficiently strong material, the sheet 118 may have a thickness of about one to about three thousandths of an inch. The sheet 118 may instead be formed of sections of rigid material joined by flexible links.
A working surface of the sheet 118 (e.g., an area on the top surface of the sheet 118 within the working volume 114) may be treated in a variety of manners to assist with adhesion of build material to the surface 118 and/or removal of completed objects from the surface 118. For example, the working surface may be abraded or otherwise textured (e.g., with grooves, protrusions, and the like) to improve adhesion between the working surface and the build material.
A variety of chemical treatments may be used on the working surface of the sheet 118 of material to further facilitate build processes as described herein. For example, the chemical treatment may include a deposition of material that can be chemically removed from the conveyer 104 by use of water, solvents, or the like. This may facilitate separation of a completed object from the conveyer by dissolving the layer of chemical treatment between the object 112 and the conveyor 104. The chemical treatments may include deposition of a material that easily separates from the conveyer such as a wax, mild adhesive, or the like. The chemical treatment may include a detachable surface such as an adhesive that is sprayed on to the conveyer 104 prior to fabrication of the object 112.
In one aspect, the conveyer 104 may be formed of a sheet of disposable, one-use material that is fed from a dispenser and consumed with each successive build.
In one aspect, the conveyer 104 may include a number of different working areas with different surface treatments adapted for different build materials or processes. For example, different areas may have different textures (smooth, abraded, grooved, etc.). Different areas may be formed of different materials. Different areas may also have or receive different chemical treatments. Thus a single conveyer 104 may be used in a variety of different build processes by selecting the various working areas as needed or desired.
The extruder 106 may include a chamber 122 in an interior thereof to receive a build material. The build material may, for example, include acrylonitrile butadiene styrene (“ABS”), high-density polyethylene (“HDPL”), polylactic acid, or any other suitable plastic, thermoplastic, or other material that can usefully be extruded to form a three-dimensional object. The extruder 106 may include an extrusion tip 124 or other opening that includes an exit port with a circular, oval, slotted or other cross-sectional profile that extrudes build material in a desired cross-sectional shape.
The extruder 106 may include a heater 126 to melt thermoplastic or other meltable build materials within the chamber 122 for extrusion through an extrusion tip 124 in liquid form. While illustrated in block form, it will be understood that the heater 124 may include, e.g., coils of resistive wire wrapped about the extruder 106, one or more heating blocks with resistive elements to heat the extruder 106 with applied current, an inductive heater, or any other arrangement of heating elements suitable for creating heat within the chamber 122 to melt the build material for extrusion. The extruder 106 may also or instead include a motor 128 or the like to push the build material into the chamber 122 and/or through the extrusion tip 126.
In general operation (and by way of example rather than limitation), a build material such as ABS plastic in filament form may be fed into the chamber 122 from a spool or the like by the motor 128, melted by the heater 126, and extruded from the extrusion tip 124. By controlling a rate of the motor 128, the temperature of the heater 126, and/or other process parameters, the build material may be extruded at a controlled volumetric rate. It will be understood that a variety of techniques may also or instead be employed to deliver build material at a controlled volumetric rate, which may depend upon the type of build material, the volumetric rate desired, and any other factors. All such techniques that might be suitably adapted to delivery of build material for fabrication of a three-dimensional object are intended to fall within the scope of this disclosure. Other techniques may be employed for three-dimensional printing, including extrusion-based techniques using a build material that is curable and/or a build material of sufficient viscosity to retain shape after extrusion.
The x-y-z positioning assembly 108 may generally be adapted to three-dimensionally position the extruder 106 and the extrusion tip 124 within the working volume 114. Thus by controlling the volumetric rate of delivery for the build material and the x, y, z position of the extrusion tip 124, the object 112 may be fabricated in three dimensions by depositing successive layers of material in two-dimensional patterns derived, for example, from cross-sections of a computer model or other computerized representation of the object 112. A variety of arrangements and techniques are known in the art to achieve controlled linear movement along one or more axes. The x-y-z positioning assembly 108 may, for example, include a number of stepper motors 109 to independently control a position of the extruder within the working volume along each of an x-axis, a y-axis, and a z-axis. More generally, the x-y-z positioning assembly 108 may include without limitation various combinations of stepper motors, encoded DC motors, gears, belts, pulleys, worm gears, threads, and the like. Any such arrangement suitable for controllably positioning the extruder 106 within the working volume 114 may be adapted to use with the printer 100 described herein.
By way of example and not limitation, the conveyor 104 may be affixed to a bed that provides x-y positioning within the plane of the conveyor 104, while the extruder 106 can be independently moved along a z-axis. As another example, the extruder 106 may be stationary while the conveyor 104 is x, y, and z positionable. As another example, the extruder 106 may be x, y, and z positionable while the conveyer 104 remains fixed (relative to the working volume 114). In yet another example, the conveyer 104 may, by movement of the sheet 118 of material, control movement in one axis (e.g., the y-axis), while the extruder 106 moves in the z-axis as well as one axis in the plane of the sheet 118. Thus in one aspect, the conveyor 104 may be attached to and move with at least one of an x-axis stage (that controls movement along the x-axis), a y-axis stage (that controls movement along a y-axis), and a z-axis stage (that controls movement along a z-axis) of the x-y-z positioning assembly 108. More generally, any arrangement of motors and other hardware controllable by the controller 110 may serve as the x-y-z positioning assembly 108 in the printer 100 described herein. Still more generally, while an x, y, z coordinate system serves as a convenient basis for positioning within three dimensions, any other coordinate system or combination of coordinate systems may also or instead be employed, such as a positional controller and assembly that operates according to cylindrical or spherical coordinates.
The controller 110 may be electrically coupled in a communicating relationship with the build platform 102, the conveyer 104, the x-y-z positioning assembly 108, and the other various components of the printer 100. In general, the controller 110 is operable to control the components of the printer 100, such as the build platform 102, the conveyer 104, the x-y-z positioning assembly 108, and any other components of the printer 100 described herein to fabricate the object 112 from the build material. The controller 110 may include any combination of software and/or processing circuitry suitable for controlling the various components of the printer 100 described herein including without limitation microprocessors, microcontrollers, application-specific integrated circuits, programmable gate arrays, and any other digital and/or analog components, as well as combinations of the foregoing, along with inputs and outputs for transceiving control signals, drive signals, power signals, sensor signals, and the like. In one aspect, the controller 110 may include a microprocessor or other processing circuitry with sufficient computational power to provide related functions such as executing an operating system, providing a graphical user interface (e.g., to a display coupled to the controller 110 or printer 100), convert three-dimensional models into tool instructions, and operate a web server or otherwise host remote users and/or activity through the network interface 136 described below.
A variety of additional sensors may be usefully incorporated into the printer 100 described above. These are generically depicted as sensor 134 in FIG. 1, for which the positioning and mechanical/electrical interconnections with other elements of the printer 100 will depend upon the type and purpose of the sensor 134 and will be readily understood and appreciated by one of ordinary skill in the art. The sensor 134 may include a temperature sensor positioned to sense a temperature of the surface of the build platform 102. This may, for example, include a thermistor or the like embedded within or attached below the surface of the build platform 102. This may also or instead include an infrared detector or the like directed at the surface 116 of the build platform 102 or the sheet 118 of material of the conveyer 104. Other sensors that may be usefully incorporated into the printer 100 as the sensor 134 include a heat sensor, a volume flow rate sensor, a weight sensor, a sound sensor, and a light sensor. Certain more specific examples are provided below by way of example and not of limitation.
The sensor 134 may include a sensor to detect a presence (or absence) of the object 112 at a predetermined location on the conveyer 104. This may include an optical detector arranged in a beam-breaking configuration to sense the presence of the object 112 at a location such as an end of the conveyer 104. This may also or instead include an imaging device and image processing circuitry to capture an image of the working volume 114 and analyze the image to evaluate a position of the object 112. This sensor 134 may be used for example to ensure that the object 112 is removed from the conveyor 104 prior to beginning a new build at that location on the working surface such as the surface 116 of the build platform 102. Thus the sensor 134 may be used to determine whether an object is present that should not be, or to detect when an object is absent. The feedback from this sensor 134 may be used by the controller 110 to issue processing interrupts or otherwise control operation of the printer 100.
The sensor 134 may include a sensor that detects a position of the conveyer 104 along the path. This information may be obtained from an encoder in a motor that drives the conveyer 104, or using any other suitable technique such as a visual sensor and corresponding fiducials (e.g., visible patterns, holes, or areas with opaque, specular, transparent, or otherwise detectable marking) on the sheet 118.
The sensor 134 may include a heater (instead of or in addition to the thermal element 130) to heat the working volume 114 such as a radiant heater or forced hot air to maintain the object 112 at a fixed, elevated temperature throughout a build. The sensor 134 may also or instead include a cooling element to maintain the object 112 at a predetermined sub-ambient temperature throughout a build.
The sensor 134 may also or instead include at least one video camera. The video camera may generally capture images of the working volume 114, the object 112, or any other hardware associated with the printer 100. The video camera may provide a remote video feed through the network interface 136, which feed may be available to remote users through a user interface maintained by, e.g., remote hardware, or within a web page provided by a web server hosted by the three-dimensional printer 100. Thus, in one aspect there is a user interface adapted to present a video feed from at least one video camera of a three-dimensional printer to a remote user through a user interface.
The sensor 134 may include may also include more complex sensing and processing systems or subsystems, such as a three-dimensional scanner using optical techniques (e.g., stereoscopic imaging, or shape from motion imaging), structured light techniques, or any other suitable sensing and processing hardware that might extract three-dimensional information from the working volume 114. In another aspect, the sensor 134 may include a machine vision system that captures images and analyzes image content to obtain information about the status of a job, working volume 114, or an object 112 therein. The machine vision system may support a variety of imaging-based automatic inspection, process control, and/or robotic guidance functions for the three-dimensional printer 100 including without limitation pass/fail decisions, error detection (and corresponding audible or visual alerts), shape detection, position detection, orientation detection, collision avoidance, and the like.
Other components, generically depicted as other hardware 135, may also be included, such as input devices including a keyboard, touchpad, mouse, switches, dials, buttons, motion sensors, and the like, as well as output devices such as a display, a speaker or other audio transducer, light emitting diodes, and the like. Other hardware 135 may also or instead include a variety of cable connections and/or hardware adapters for connecting to, e.g., external computers, external hardware, external instrumentation or data acquisition systems, and the like.
The printer 100 may include, or be connected in a communicating relationship with, a network interface 136. The network interface 136 may include any combination of hardware and software suitable for coupling the controller 110 and other components of the printer 100 to a remote computer in a communicating relationship through a data network. By way of example and not limitation, this may include electronics for a wired or wireless Ethernet connection operating according to the IEEE 802.11 standard (or any variation thereof), or any other short or long range wireless networking components or the like. This may include hardware for short range data communications such as BlueTooth or an infrared transceiver, which may be used to couple into a local area network or the like that is in turn coupled to a data network such as the Internet. This may also or instead include hardware/software for a WiMax connection or a cellular network connection (using, e.g., CDMA, GSM, LTE, or any other suitable protocol or combination of protocols). Consistently, the controller 110 may be configured to control participation by the printer 100 in any network to which the network interface 136 is connected, such as by autonomously connecting to the network to retrieve printable content, or responding to a remote request for status or availability.
An extruder assembly including a quick-release extruder will now be described.
The extruder assembly with a quick-release extruder may include any of the features described herein including the features described in U.S. Provisional Application No. 61/719,874, which is hereby incorporated by reference in its entirety.
In a three-dimensional printer, a filament of build material may be supported by and in contact with a drive gear. Also, a filament of build material may be in contact with a drive gear via a bearing, which may be a spring-loaded bearing or the like. The bearing may provide a substantially constant contact force against the filament and toward the drive gear. The bearing may include a quick-release lever or the like to move the bearing away from the drive gear for, e.g., access to and maintenance of an extruder assembly. This arrangement may also permit quick loading, unloading, and replacement of filament of material for a three-dimensional printer.
FIG. 2 is an exploded view of an extruder assembly 200. In general, the extruder assembly 200 may include a drive gear 202 with an arrangement of teeth 210 or other protrusions to grip and advance a filament (not shown) through the extruder assembly 200. The drive gear 202 may be disposed adjacent to a feedpath passing through the extruder assembly 200 along which a filament of build material travels during an extrusion. The feedpath may be defined by the path taken by the filament through the extruder assembly 200, where the filament enters the feedpath through an input opening 212, travels through a chamber 214, engages with a drive gear 202 and a bearing 204, and travels through an opening 216 in a heating block 218. Alternatively, the feedpath may be defined as the path taken by the filament before and after engagement with the drive gear 202. The opening 216 for the feedback may be formed in the heating block 218, which may include a heating element, thermistors, and so forth for heating the heating block and creating a melt chamber within the opening 216. An extrusion tip may be formed into a bottom of the opening 216, or the bottom of the opening 216 may be threaded to removably and replaceably receive a nozzle having on orifice to extrude liquefied material with a desired cross sectional shape. The drive gear 202 may be powered by any suitable electromechanical device such as a stepper motor or the like, and imparts a drive force on a filament by gripping the filament with the teeth 210 and rotating to move the filament along the feedpath.
A bearing 204 may be any free-rolling contact surface that can apply force normal to the drive gear 202 in order for the teeth 210 to engagement the filament without inhibiting motion of the filament along the feedpath. The bearing 204 may have a smooth, substantially cylindrical exterior, and may be positioned on an axis 220 substantially parallel to an axis 222 of the drive gear 202. The bearing 204 may also have a different shape than is shown in FIG. 2, which may be based on the configuration and/or type of the drive gear and/or build material and/or filament used with the extruder assembly 200. Additionally, the bearing 204 may generally include any suitable mechanical components for relatively low-friction rotation about its axis. A variety of rolling and hydrostatic bearings and the like are known in the art, any of which may be used as the bearing 204 described herein.
The bearing 204 may be disposed such that it is at a distance where it may apply a force against the drive gear 202 to a filament of suitable diameter that passes between the drive gear 202 and the bearing 204. A spring 206 may be positioned to apply a substantially constant force to the bearing 204 toward the drive gear 202 so that the drive gear 202 can engage the filament. This arrangement advantageously permits the drive gear 202 and bearing 204 to accommodate defects in a filament and variations in filament diameter while maintaining a consistent gripping force to drive the filament. A coil spring may conveniently be employed as the spring 206, however a variety of springs and biasing members are known in the art that may be adapted to provide a biasing force to maintain a position of the bearing 204 and/or the drive gear 202 relative to one another. Moreover, the force to maintain a position of the bearing and/or the drive gear relative to one another may be provided by an actuator, a piston, or the like.
A lever 208 may be provided as a mechanism to position the bearing 204 relative to the drive gear 202. By operating the lever 208, the bearing 204 may be moved closer to the drive gear 202 (e.g., in order to engage a filament) or farther from the drive gear 202 (e.g., in order to disengage the filament for removal or other maintenance). It will be understood that the lever may be simple lever, e.g., a spring-loaded lever on a pivot. In an embodiment, when the lever is in a first position the bearing is engaged with the drive gear, and when the lever is in a second position the bearing is disengaged from the drive gear. It will also be understood that the lever 208 may be a bistable lever or the like, where the bistable lever may be associated with a second lever 224 (as shown in FIG. 2) that is directly coupled to an axle 225 of the bearing 204. In this configuration, the second lever 224 is urged by the spring 206 toward the drive gear 202 about a pivot 227 in the absence of external forces. The lever 208 can then be operated to contact a beveled surface 229 of the second lever 224 and drive the second lever 224 away from the drive gear 202 against the force of the spring 206. An arm of the lever 208 may extend from the extruder assembly 200 for hand manipulation. Bistable operation of the lever 208 may be achieved, for example, by forming an L near the pivot point (as illustrated below in FIG. 6) that locks the bearing 204 in an open (i.e., away from the drive gear) position when the lever 208 is moved beyond a certain rotation. In this respect, the L cooperates with the beveled surface 229 to create a force that retains the open position when the lever 208 is moved to one side. Thus the assembly has a first stable position (a “closed position) in which the bearing engages a filament with the drive gear and a second stable position (an “open position”) in which the bearing does not engage a filament with the drive gear.
An example of a lever is shown in FIG. 2, but it will be understood that different types of levers and/or mechanical elements may be used to similar affect. For example, the lever may further include additional levers, pivoting links, and the like that cooperate to move the bearing from a first position where it is engaged with the drive gear to a second position where it is disengaged from the drive gear. Similarly, while the bistable lever described above automatically locks in an open or closed position, manual locking mechanism may also or instead be employed, such as with a single spring-loaded lever and an external locking mechanism that can secure the bearing 204 in an open position against the force of a spring.
Further, it will be understood that a variety of mechanical arrangements may be used to similar affect to release the extruder assembly components. The lever may also or instead include a button, a knob, a slider, or any other mechanical arrangement suitable for moving the bearing 204 into and out of engagement with the drive gear 202, or more generally farther from or closer to the drive gear 202, which may include moving the axle 225 of the bearing 204 farther from or closer to the drive gear 202, preferably while maintaining a generally parallel orientation of the axis 222 of the drive gear with the axis 220 of the bearing. It will be appreciated that the two axes 220, 222 need not be perfectly parallel at all times and that, by way of example, the axes 220, 222 may move out of a parallel arrangement when the axis 220 of the bearing is moved away from the axis 222 of the drive gear for loading and unloading of a filament. All such arrangements suitable for tension control and/or quick release may be used with the extruder assemblies described herein, and are intended to fall within the scope of this disclosure.
FIGS. 3-7 show a number of views of an extruder assembly that may be used as any of the extruder assemblies described above.
FIG. 3 shows a perspective view of an extruder assembly 300, where the feedpath 301, drive gear 302, bearing 304, lever 308, and input opening 312 are visible. Also, as shown in FIG. 3, the extruder assembly 300 may generally include a housing 303 for the components of the extruder assembly 300, which may be a two-part housing formed of two portions that can be joined for use as an extruder assembly. While the housing may also be formed as a single integral piece, a two-part construction advantageously facilitates disassembly to service parts within the extruder assembly 300.
FIG. 4 shows a left side view of an extruder assembly 400, where the feedpath 401, drive gear 402, bearing 404, lever 408, and input opening 412 are visible. Also, as shown in FIG. 4, the extruder assembly 400 may generally include a housing 403 for the components of the extruder assembly 400.
FIG. 5 shows a front view of an extruder assembly 500, where the feedpath 501, lever 508, and input opening 512 are visible. Also, as shown in FIG. 5, the extruder assembly 500 may generally include a housing 503 for the components of the extruder assembly 500.
FIG. 6 shows a right side view of an extruder assembly 600, where the feedpath 601, drive gear 602, bearing 604, spring 606, lever 608, input opening 612, and second lever 624 are visible. As shown in FIG. 6, the lever 608 may be disposed in a first position (as shown in FIG. 6, i.e., where the lever 608 rests on the right side of the extruder assembly 600), where the bearing 604 is engaged with the drive gear 602. If the lever 608 is manually moved from the right side of the extruder assembly 600 to the left side of the extruder assembly 600, the second lever 624 can rotate about a pivot (not shown) against a biasing force of the spring 606 so that the bearing 604 moves out of engagement with the drive wheel 602. Although not illustrated, it will be noted that an L 630 on the lever 608 can be shaped so that in this second position, an upward force between the L 630 and the beveled end of the second lever 624 retains the lever 608 and the second lever 624 in the open position to provide a bistable lever. In another aspect, the L may be omitted and the bearing 604 may be urged into engagement with the drive gear 602 whenever an external force is removed from the lever 608.
FIG. 7 shows a top view of an extruder assembly 700, where the lever 708 and input opening 712 are visible. Also, as shown in FIG. 7, the extruder assembly 700 may generally include a housing 703 for the components of the extruder assembly 700.
While particular embodiments have been shown and described, it will be apparent to those skilled in the art that various changes and modifications in form and details may be made therein without departing from the spirit and scope of this disclosure and are intended to form a part of the invention as defined by the following claims, which are to be interpreted in the broadest sense allowable by law.