Patent Grant
11237542
Aspects relate to three dimensional printing.
In Composite Filament Fabrication (“CFF”), toolpaths may be generated, traced and/or followed by an continuous fiber composite reinforced 3D printer, in the form of deposited bonded ranks or composite swaths. Toolpaths may follow contours (e.g., within an offset path parallel to a contour), follow patterns (e.g., boustrophedon rows, or spirals), may form transitions between offsets and printed areas, e.g., form a crossover from one offset to an adjacent offset. A core reinforced fiber toolpath may be cloned into an adjacent layer (e.g., “cloned” meaning identically), or reproduced with changes that avoid stacking seams or stress concentrations. Different core reinforced toolpaths having a different directions of reinforcement may be used in different layers.
Additionally, and/or alternatively, as discussed in the present disclosure, new toolpaths and modifications of these toolpaths may overlap toolpaths of different trajectories in a manner to create complementary toolpaths within, between layers and among layers of matrix and/or fill material.
In one embodiment, or embodiment of the invention, a method for additive manufacturing may include supplying a multi-strand core reinforced filament including a flowable matrix material permeating or embedding substantially continuous reinforcing strands (optionally of a material having a tensile strength of greater than 300 MPa). The substantially continuous reinforcing strands may extend in a direction parallel to a length of the filament. A first consolidated composite swath (optionally of a height less than ½ the width of the filament) may be deposited in a first reinforcement formation including at least one straight path and at least one curved path, by flowing the matrix material and applying an ironing force that spreads the reinforcing strands within the filament against a deposition surface. A second consolidated composite swath (optionally of a height less than ½ the width of the filament) may be deposited in a second reinforcement formation including at least one straight path and at least one curved path, by flowing the matrix material and applying an ironing force to spread the reinforcing strands within the filament against the first consolidated composite swath.
In another embodiment, or embodiment of the invention, a 3D printer for additive manufacturing of a part may include a composite swath deposition head that deposits consolidated composite swaths from a supply of multi-strand core reinforced filament including a flowable matrix material and a plurality of substantially continuous reinforcing strands, the substantially continuous reinforcing strands extending in a direction parallel to a length of the filament. A motorized drive may relatively move at least the composite swath deposition head and a build plate supporting a 3D printed part in at least three degrees of freedom. A controller may be configured to control the motorized drive and the composite swath deposition head (each of which the controller is operatively connected to) to build the 3D printed part by depositing a first consolidated composite swath in a first reinforcement formation including at least one straight path and at least one curved path, by flowing the matrix material and applying, with the composite swath deposition head, an ironing force that spreads the reinforcing strands within the filament against a deposition surface. The controller may further be configured to deposit a second consolidated composite swath in a second reinforcement formation including at least one straight path and at least one curved path, by flowing the matrix material and applying, with the composite swath deposition head, an ironing force to spread the reinforcing strands within the filament against the first consolidated composite swath.
Optionally, at least one cover of fill material or multi-strand core reinforced filament may be deposited in a layer adjacent the location at which the ironing force spreads the reinforcing strands of the second consolidated composite swath against the first consolidated composite swath, the cover having a thickness of less than the height of the layer.
Further optionally, the method may include, or the 3D printer controller may be configured to control the 3D printer components to which it is operatively connected to build a part by, turning the first fused composite swath according to the first reinforcement formation toward a different direction at a first location, and/or turning the second consolidated fibers swath according to the second reinforcement formation toward a different direction at a second location displaced from the first location in at least two orthogonal directions.
Still further optionally, the first consolidated composite swath and the second consolidated composite swath may be deposited as a continuous composite swath within a single shell of an additive manufacturing process. Alternatively or in addition, the second consolidated composite swath may be deposited with less ironing force than the first consolidated composite swath; and/or the second consolidated composite swath may be deposited at a nozzle height from the first consolidated composite swath that is different from a previously deposited layer height; and/or fill material may be deposited horizontally about the common overlap of the first consolidated composite swath and the second consolidated composite swath at a width of 1/10 to 2 times the width of the first consolidated composite swath.
Further optionally, the linear speed at which the second consolidated composite swath is ironed against the first consolidated composite swath is 1/10 to 9/10 a linear speed at which the first consolidated composite swath was deposited; and/or a filament feeding rate at which the filament for the second consolidated composite swath is supplied may be greater than the linear speed at which the second consolidated composite swath is ironed against the first consolidated composite swath by 1 to 20%.
Alternatively or in addition, a tension along the composite swath at which the first consolidated composite swath is deposited may be reduced at a location at which the second consolidated composite swath is ironed against the first consolidated composite swath.
Further optionally, the method may include, or the 3D printer controller may be configured to control the 3D printer components to which it is operatively connected to build a part by, depositing the second consolidated composite swath in a second reinforcement formation that extends substantially parallel to the first reinforcement formation, wherein composite swaths of the second reinforcement formation may be deposited at a second pitch substantially the same as a first pitch of the first reinforcement formation and displaced by a distance of substantially half the first pitch.
Alternatively or in addition, the first consolidated composite swath and second consolidated composite swath may be deposited in a location adjacent to and reinforcing a negative subcontour, and/or the first consolidated composite swath and second consolidated composite swath may be deposited in respective first and second layers in locations adjacent to and reinforcing a negative subcontour extending through each of the respective first and second layers.
Alternatively or in addition, the method may include, or the 3D printer controller may be configured to control the 3D printer components to which it is operatively connected to build a part by, depositing the first consolidated composite swath and the second consolidated composite swath as a continuous composite swath spanning two shells of an additive manufacturing process; and/or depositing the first consolidated composite swath in a first reinforcement formation that has a higher strength in tension between a first negative contour and a second negative contour than the second reinforcement formation.
In a further embodiment, or embodiment of the invention, a method for printing a part with a three dimensional printer may include receiving toolpath instructions having a plurality of single layer toolpaths encoded with first and second degrees of freedom, and/or supplying a strand reinforced composite filament having reinforcing strands embedded in a flowable matrix. Consolidated composite swaths may be deposited by controlling a print head to output the strand reinforced composite filament with the reinforcing strands oriented parallel to a trajectory of the print head, and/or by controlling the print head to iron the strand reinforced composite filament to form consolidated composite swaths having reinforcing strands spread out against a surface. A first consolidated composite swath may be deposited according to a first single layer toolpath within a first layer, and/or a second consolidated composite swath may be deposited according to a second single layer toolpath within the same first layer, the second consolidated composite swath having a crossing point with the first consolidated composite swath within the same first layer. The second consolidated composite swath may be ironed to spread against the first consolidated composite swath.
In another embodiment, or embodiment of the invention, a 3D printer for additive manufacturing of a part may include a composite swath deposition head that deposits consolidated composite swaths from a supply of strand reinforced composite filament having reinforcing strands embedded in a flowable matrix, a motorized drive for relatively moving at least the composite swath deposition head and a build plate supporting a 3D printed part in at least three degrees of freedom, and a controller. The controller may be configured to control the motorized drive and the composite swath deposition head (each of which the controller is operatively connected to) to deposit consolidated composite swaths to build the 3D printed part according to toolpath instructions having a plurality of single layer toolpaths encoded with at least first and second degrees of freedom. The controller may be configured to control the composite swath deposition head to output the strand reinforced composite filament with the reinforcing strands oriented parallel to a trajectory of the composite swath deposition head, and/or control the composite swath deposition head to iron the strand reinforced composite filament to form consolidated composite swaths having reinforcing strands spread out against a surface. The controller may also be configured to deposit a first consolidated composite swath according to a first single layer toolpath within a first layer, and/or deposit a second consolidated composite swath according to a second single layer toolpath within the same first layer, the second consolidated composite swath having a crossing point with the first consolidated composite swath within the same first layer, and/or iron the second consolidated composite swath to spread against the first consolidated composite swath.
Optionally, the first and second single layer toolpaths may form a closed loop from the continuous strand reinforced composite filament, and the first and second consolidated composite swaths may form a crossing turn within the same first layer.
Further optionally, the closed loop and/or the crossing turn may be deposited in a location adjacent to and reinforcing a negative subcontour within an interior of the same first layer. Alternatively or in addition, a third consolidated composite swath may be deposited in a location adjacent to and reinforcing the closed loop and crossing turn in one of the same first layer or an adjacent second layer.
The method may also include, or the 3D printer controller may be configured to control the 3D printer components to which it is operatively connected to build a part by, alternatively or in addition, controlling the print head to iron the strand reinforced composite filament to form consolidated composite swaths having reinforcing strands spread out against a surface by, for example, flowing the matrix material, and/or applying an ironing force that spreads the reinforcing strands, and/or forming consolidated composite swaths of a height less than ½ the width of the strand reinforced composite filament.
In a further embodiment, or embodiment of the invention, a method for additive manufacturing may include supplying a strand reinforced composite filament including a flowable matrix material and a plurality of substantially continuous reinforcing strands of a fiber material having a tensile strength of greater than 300 MPa, the substantially continuous reinforcing strands extending in a direction parallel to a length of the filament. Toolpath instructions may be received having a plurality of single layer toolpaths encoded with first and second degrees of freedom. Composite swaths may be consolidated by, e.g., controlling the print head to iron the strand reinforced composite filament to less than ½ the width of the strand reinforced composite filament to form consolidated composite swaths having reinforcing strands spread out against a surface; and/or depositing a first reinforcement formation including a plurality of interconnected straight segments and curved segment; and/or depositing a second reinforcement formation including a plurality of interconnected straight segments and curved segments, different from the first reinforcement formation. On curved segments which change a direction of a connected straight segment by more than 45 degrees, the printhead may be controlled to deposit consolidated composite swaths in a toolpath that is different from the embedded path of the consolidated composite swath.
In an additional embodiment, or embodiment of the invention, 3D printer for additive manufacturing of a part may include a composite filament deposition head that deposits strand reinforced composite filament from a supply of strand reinforced composite filament including a flowable matrix material and a plurality of substantially continuous reinforcing strands of a fiber material having a tensile strength of greater than 300 MPa, the substantially continuous reinforcing strands extending in a direction parallel to a length of the filament, and a motorized drive for relatively moving at least the composite filament deposition head and a build plate supporting a 3D printed part in at least three degrees of freedom. A controller may be configured to control the motorized drive, the composite swath deposition head and the isotropic solidifying head (each of which to which the controller is operatively connected) to deposit consolidated composite swaths to build the 3D printed part according to toolpath instructions having a plurality of single layer toolpaths encoded with at least first and second degrees of freedom. The controller may further be configured to control the composite filament deposition head to iron the strand reinforced composite filament to less than ½ the width of the strand reinforced composite filament to form consolidated composite swaths having reinforcing strands spread out against a surface. The controller may further be configured to deposit a first reinforcement formation including a plurality of interconnected straight segments and curved segments. The controller may further be configured to deposit a second reinforcement formation including a plurality of interconnected straight segments and curved segments, different from the first reinforcement formation. The controller may further be configured to, on curved segments which change a direction of a connected straight segment by more than 45 degrees, control the composite filament deposition head to deposit consolidated composite swaths in a toolpath that is different from the embedded path of the consolidated composite swath.
Optionally, on curved segments which change a direction of a connected straight segment by more than 45 degrees, the printhead may be controlled to deposit consolidated composite swaths in a toolpath is a longer linear trajectory than the embedded path of the consolidated composite swath. Alternatively, or in addition, on curved segments which change a direction of a connected straight segment by more than 45 degrees, the printhead may be controlled to deposit consolidated composite swath in a toolpath that folds the consolidated composite swath in a curved segment of the consolidated composite swath. Further alternatively or in addition, on curved segments which change a direction of a connected straight segment by more than 45 degrees, the printhead may be controlled to deposit consolidated composite swaths in a toolpath that folds the consolidated composite swath by moving many fibers within the consolidated composite swath from one lateral location to a displaced lateral location along a curved segment of the consolidated composite path.
In another embodiment, or embodiment of the invention, a method for sparse fill in additive manufacturing may include supplying a multi-strand core reinforced filament including a flowable matrix material and a plurality of substantially continuous reinforcing strands (optionally of a material having a tensile strength of greater than 300 MPa), the substantially continuous reinforcing strands extending in a direction parallel to a length of the filament. Within a first layer, a first consolidated composite swath may be deposited (optionally of a height less than ½ the width of the filament) in a first reinforcement formation including a first plurality of parallel lengths each extending in a first direction by flowing the matrix material and applying an ironing force that spreads the reinforcing strands within the filament against a deposition surface. Within the same first layer, a second consolidated composite swath may be deposited (optionally of a height less than ½ the width of the filament) in a second reinforcement formation including a second plurality of parallel lengths each extending a second direction angled from the first direction by sixty degrees, by flowing the matrix material and applying an ironing force to spread the reinforcing strands within the filament against the first plurality of parallel lengths of the first consolidated composite swath. In a second layer above the first layer, a third consolidated composite swath may be deposited (optionally of a height less than ½ the width of the filament) in a third reinforcement formation including a third plurality of parallel lengths each extending a third direction angled from the first and second directions by sixty degrees, by flowing the matrix material and applying an ironing force to spread the reinforcing strands within the filament against the first and second pluralities of parallel lengths of the first and second consolidated composite swaths.
Optionally, the third consolidated composite swath may be deposited with the third plurality of parallel lengths each crossing an intersection of the first and second consolidated composite swaths. Alternatively, or in addition, the third consolidated composite swath may be deposited with the third plurality of parallel lengths each offset from an intersection of the first and second consolidated composite swaths.
In another embodiment, or embodiment of the invention, a method for sparse fill in additive manufacturing may include supplying a filament including a flowable polymer material. Within a first layer, rows of the flowable polymer material may be deposited in a first reinforcement formation including a first plurality of parallel lengths each extending in a first direction by flowing the flowable polymer material against a deposition surface. Within the same first layer, rows of the flowable polymer material may be deposited in a second reinforcement formation including a second plurality of parallel lengths each extending in a second direction angled from the first direction by sixty degrees, by flowing the flowable polymer material against the deposition surface and to thin out when the second plurality of parallel lengths crosses the first plurality of parallel lengths of the rows of the flowable polymer material. Within the same first layer, rows of the flowable polymer material may be deposited in a third reinforcement formation including a third plurality of parallel lengths each extending in a third direction angled from the first and second directions by sixty degrees, by flowing the matrix material against the deposition surface and to thin out when the third plurality of parallel lengths crosses the first and second pluralities of parallel lengths of the first and second rows of the flowable polymer material.
Optionally, supplying a filament may include supplying a multi-strand core reinforced filament including a flowable polymer matrix material and a plurality of substantially continuous reinforcing strands (optionally of a material having a tensile strength of greater than 300 MPa) extending in a direction parallel to a length of the filament. Each row of flowable polymer material may be deposited as a consolidated composite swath (optionally of a height less than ½ the width of the filament) by flowing the polymer matrix material against a previously deposited row and applying an ironing force that spreads the reinforcing strands within the filament against the previously deposited row. The third plurality of parallel lengths may be deposited with each parallel length offset from an intersection of the first and second consolidated parallel lengths.
In another embodiment, or embodiment of the invention, a method for generating three-dimensional toolpath instructions for a three dimensional printer may include receiving a three-dimensional geometry, then slicing the three-dimensional geometry into layers (or shells). Toolpath instructions may be generated to deposit consolidated composite swaths by ironing strand reinforced composite filament to form consolidated composite swaths having reinforcing strands spread out against a surface. Toolpath instructions may be generated to deposit a first consolidated composite swath according to a first single layer toolpath within a first layer of the layers. Toolpath instructions may also be generated to deposit a second consolidated composite swath according to a second single layer toolpath within the same first layer, the second consolidated composite swath having a crossing point with the first consolidated composite swath within the same first layer. Toolpath instructions may further be generated to iron the second consolidated composite swath to spread against the first consolidated composite swath within the same first layer.
This patent application incorporates the following disclosures by reference in their entireties: U.S. patent application Ser. Nos. 61/804,235; 61/815,531; 61/831,600; 61/847,113; 61/878,029; 61/880,129; 61/881,946; 61/883,440; 61/902,256; 61/907,431; 62/080,890, and 62/172,021; 14/222,318; 14/297,437; and 14/333,881, which may be referred to herein as “Composite Filament Fabrication patent applications” or “CFF patent applications”.
Each of
Although
The fiber reinforced composite filament 2, 2a is fed, dragged, and/or pulled through a conduit nozzle 10 heated to a controlled temperature selected for the matrix material to maintain a predetermined viscosity, force of adhesion of bonded ranks, melting properties, and/or surface finish.
After having the matrix material or polymer 4, 4a substantially melted, the continuous core reinforced filament 2 is applied onto a build platen 16 to build successive layers 14 to form a three dimensional structure. The relative position and/or orientation of the build platen 16 and conduit nozzle 10 are controlled by a controller 20 to deposit the continuous core reinforced filament 2 in the desired location and direction.
A cutter 8 controlled by the controller 20 may cut the continuous core reinforced filament during the deposition process in order to (i) form separate features and components on the structure as well as (ii) control the directionality or anisotropy of the deposited material and/or bonded ranks in multiple sections and layers. At least one secondary print head 18 may print fill material 18a to form walls, infill, protective coatings, and/or support material.
The supplied filament includes at least one axial fiber strand 6, 6a extending within a matrix material 4, 4a of the filament, for example a nylon matrix 4a that impregnates hundreds or thousands of continuous carbon, aramid, glass, basalt, or UHMWPE fiber strands 6a. The fiber strand material has an ultimate tensile strength of greater than 300 MPa.
The driven roller set 42, 40 push the unmelted filament 2 along a clearance fit zone that prevents buckling of filament 2. In a threading stage, the melted matrix material 6a and the axial fiber strands 4a of the filament 2 are pressed into the part 14 and/or swaths below 2d, at times with axial compression. As the build platen 16 and print head(s) are translated with respect to one another, the end of the filament 2 contacts the ironing lip 726 and is subsequently continually ironed in a transverse pressure zone 3040 to form bonded ranks or composite swaths in the part 14.
The feed rate (the tangential or linear speed of the drive 42, 40) and/or printing rate (e.g., the relative linear speed of the platen/part and print head) may be monitored or controlled to maintain compression, neutral tension, or positive tension within the unsupported zone as well as primarily via axial compressive or tensile force within fiber strand(s) 6a extending along the filament 2.
As shown in
Unmelted fiber reinforced filament may be cut in a gap 62 between a guide tube 72 (having a clearance fit) and the conduit nozzle 708; or within the conduit nozzle 708, e.g., upstream of the non-contact zone 3030; and/or at the clearance fit zone 3010, 3020 or the ironing lip 725.
After the matrix material 6a is melted by the ironing lip or tip 726, the feed and/or printing rate can be controlled by the controller 20 to maintain neutral to positive tension in the composite filament 2 between the ironing lip 726 and the part 14 primarily via tensile force within the fiber strands 4a extending along the filament 2. A substantially constant cross sectional area of the fiber reinforced composite filament is maintained in the clearance fit zone, the unsupported zone, the transverse pressure zone, and also as a bonded rank is attached to the workpiece or part 14.
With reference to
The companion continuous fiber embedded filament printhead 199, as shown, includes the conduit nozzle 708, the composite ironing tip 728, and the limited contact cavity 714, in this example each within a heating block heated by a heater 715. A cold feed zone 712 is formed within a receiving tube 64, including a capillary-like receiving tube of rigid material and a small diameter (e.g. inner diameter of 32 thou) Teflon/PTFE tube extending into the nozzle 708. The cold feed zone is surrounded in this case by an insulating block 66a and a heat sink 66b, but these are fully optional. In operation, an unattached terminal end of the fiber-embedded filament may be held in the cold feed zone, e.g., at height P1. Distance P1, as well as cutter-to-tip distance R1, are retained in a database for permitting the controller 20 to thread and advance the fiber-embedded filament as discussed herein. Further as shown, the controller 20 is operatively connected to the cutter 8, 8A, and feed rollers 42 facing idle rollers 40.
In addition, as shown essentially proportionately in
The interior strands 6a of the filament 2c both spread and intrude into adjacent bonded ranks 2c or 2d on the same layer and the matrix material 4a and strands 6a are compressed into the underlying shaped filament or bonded rank of material 2d. This pressing, compaction, or diffusion of shaped filaments or bonded ranks 2c, 2d reduces the distance between reinforcing fibers, and increases the strength of the resultant part (and replaces techniques achieved in composite lay-up using post-processing with pressure plates or vacuum bagging). Accordingly, in some embodiments or aspect of the invention discussed herein, the axial compression of the filament 2 and/or especially the physical pressing by the printer head 70, conduit nozzle or ironing lip 726 in zone 3040 may be used to apply a compression/compaction/consolidation pressure directly to the deposited material or bonded ranks or composite swaths 2c to force them to spread or compact or flatten into the ranks beside and/or below. Cross-sectional area is substantially or identically maintained.
Alternatively or in addition, pressure may be applied through a trailing pressure plate behind the print head; a full width pressure plate spanning the entire part that applies compaction pressure to an entire layer at a time; and/or heat, pressure, or vacuum may be applied during printing, after each layer, or to the part as a whole to reflow the resin in the layer and achieve the desired amount of compaction (forcing of walls together and reduction and elimination of voids) within the final part.
Description herein referring to the controller 20 of the printer 1000 performing a machine action should be interpreted as the controller 20 controlling those actuators, heaters, and effectors to which it is operatively connected to perform the recited machine action.
The controller 20 of the printer 1000, may, as described herein, supply a multi-strand core reinforced filament 2 including a flowable matrix material 4a and a plurality of substantially continuous reinforcing strands 6a. The strands are preferably of a material having a ultimate or tensile strength of greater than 300 MPa (e.g., see Materials table). The substantially continuous reinforcing strands 6a extend in a direction parallel to a length of the filament 2. The controller 20 of the printer 1000 controls the actuators and heaters to deposit a first consolidated composite swath 2c of a height less than ½ the width of the filament 2 in a first reinforcement formation, e.g., 99A-99Z, including at least one straight path 991 and at least one curved path 992. Curved paths include both (i) curves in which the corner radius is greater than 2 times the composite swath 2c width—as deposited—as well as, or the alternative (ii) sharp corners, as unfolded or folded corners, having a corner radius from 0 to twice the composite swath 2c width. The controller 20 of the printer 1000 controls the actuators and heaters to flow the matrix material 4a and applying an ironing force that spreads the reinforcing strands 6a within the filament 2a against a deposition surface 16, 14, or 2d (once spread, the material may be considered a bonded rank or consolidated swath 2c).
The controller 20 of the printer 1000 controls the actuators and heaters to deposit a second consolidated composite swath 2c, also of a height less than ½ the width of the filament, in a second reinforcement formation 99A-99Z including at least one straight path 991 and at least one curved path 992, by flowing the matrix material 4a and applying an ironing force to spread the reinforcing strands 6a within the filament 2 and/or second consolidated swath 2c-2 against the first consolidated composite swath 2c.
In some techniques disclosed herein, the controller 20 of the printer 1000 controls the actuators and heaters to deposit a first consolidated composite swath 2c-1 and the second consolidated composite swath 2c-2 as a continuous composite swath 2c within a single shell LAn of an additive manufacturing process. In alternative or additions to these techniques, the controller 20 of the printer 1000 controls the actuators and heaters to deposit the second consolidated composite swath 2c-2 with less ironing force than the first consolidated composite swath 2c-2, and/or deposit the second consolidated composite swath 2c-2 at a nozzle height NHn from the first consolidated composite swath 2c-2 that is different from a previously deposited layer height LHn.
In particular additions or alternative to these techniques, the controller 20 of the printer 1000 controls the actuators and heaters to deposit fill material 18a horizontally about the common overlap PR of the first consolidated composite swath 2c-1 and the second consolidated composite swath 2c-2 at a width of 1/10 to 2 times the width 2c-1w of the first consolidated composite swath 2c-1. The linear speed at which the second consolidated composite swath 2c-2 is ironed against the first consolidated composite swath 2c-2 is optionally 1/10 to 9/10 the linear speed at which the first consolidated composite swath 2c-1 was deposited; and/or the linear filament feeding rate at which the filament 2 for the second consolidated composite swath 2c-2 is supplied is greater than the linear printing speed at which the second consolidated composite swath 2c-2 is ironed against the first consolidated composite swath 2c-1 by 1 to 20%.
In other additions or alternative to these techniques, the controller 20 of the printer 1000 controls the actuators and heaters to maintain a tension along the composite swath 2c at which the first consolidated composite swath 2c-1 is deposited to be reduced at a location at which the second consolidated composite swath 2c-2 is ironed against the first consolidated composite swath 2c-1. In further alternatives or additions, the second consolidated composite swath 2c is deposited by the controller 20/printer 1000 in a second reinforcement formation 99A-99Z, e.g., 99A-2 that extends substantially parallel to the first reinforcement formation 99A-99Z, e.g., 99A-1, wherein composite swaths 2c of the second reinforcement formation 99A-99Z, e.g., 99A-2 are deposited at a second pitch substantially the same as a first pitch of the first reinforcement formation 99A-99Z, e.g., 99A-1, and displaced by a distance of substantially half the first pitch.
Yet further alternative or additionally, the controller 20 of the printer 1000 controls the actuators and heaters such that the first consolidated composite swath 2c and second consolidated composite swath 2c are deposited in a location adjacent to and reinforcing a negative subcontour. In this case, “reinforcing” means following or tracing along a perimeter, wall, load line, stress concentration, or a trajectory drawn between the same. “Adjacent” means immediately adjacent, and also separated by a small number (e.g., 1-5) of coating, smoothing or compliant neat material 18a walls, floors, or ceilings. A negative subcontour may be a hole, or an embedded material or object or set-aside for same, or a second object with surfaces intruding into the layer or a set-aside for the same, or an overmolding, or in some cases a touching loop surrounding a hole, embedded object, or intruding object. In this technique, alternatively or additionally the first consolidated composite swath 2c and second consolidated composite swath 2c may be deposited in respective (adjacent) first and second layers LAn, LAn+1 in locations adjacent to and reinforcing a negative subcontour extending through each of the respective first and second layers LAn, LAn+1.
Still further alternative or additionally, the controller 20 of the printer 1000 may control the actuators and heaters such that depositing the first consolidated composite swath 2c and the second consolidated composite swath 2c as a continuous composite swath 2c spanning (e.g., via inter-layer continuous traverse SP30-A, SP30-B) two shells LAn, LAn+1 of an additive manufacturing process.
Still further alternative or additionally, the controller 20 of the printer 1000 may control the actuators and heaters such that the first consolidated composite swath 2c is deposited in a first reinforcement formation 99A-99Z that has a higher strength in tension between a first negative contour (or hole Ha) and a second negative contour (or hole Hb) than the second reinforcement formation 99A-99Z.
The secondary print head 18 prints fill material to form walls, infill, protective coatings, and/or support material on each layer, and as described herein, to smooth over protrusions into neighboring layers.
As noted above, arrangements are considered within the scope of, and expressly described by, a drive system or drive or motorized drive that may relatively move a print head and a build plate supporting a 3D printed part in at least three degrees of freedom (i.e., in four or more degrees of freedom as well), such as a delta robot or robot arm drive permitting four or higher degrees of freedom among the print head and build plate. Accordingly, as used herein, “layers” and “shells” deposited by the print head(s) or deposition head(s) or solidification head(s) may mean any layer or stratum or shell that may be formed in three degrees of freedom or higher (i.e., in four or more degrees of freedom as well), as appropriate, which may be planar layers in the case of three translation degrees of freedom (although shallowly curved layers may be formed even with three translation degrees of freedom), or curved, cupped, convex, concave, or topologically or topographically complex layers, shells, or layers or shells following two dimensional manifolds. Although the Figures and examples herein often show planar layers or shells, the present description and claims expressly contemplate that a layer or shell may be curved, and the orientation of print head(s), deposition head(s) or solidification head(s) driven such that such head(s) are normal or near-normal to the surface being printed and tracking along such surface in 3D space, or otherwise appropriately oriented to deposit the layer or surface.
An optional or preferred technique for depositing a core-reinforced filament to become a fused composite swath includes compressing a core reinforced filament exiting a conduit nozzle to form a flattened shape (e.g., as discussed in the CFF patent applications).
The flattened shape is of variable height-to-width proportion, e.g., in cross-section from 1:2 through about 1:12 proportion. Preferably, the height of a compressed composite swath 2c substantially corresponds to the fill material layer height in the same layer LA1, so that neighboring composite swaths 2c in the vertical direction can be tightly packed, yet be built up as part of the same or adjacent layers as the surrounding, complementary and/or interstitial fill material 18a.
Inter-layer interaction among composite swaths 2c and fill material 18a may be more involved than interlayer interaction among layers of fill material 18a. In most cases, the only requirement for adjacent layers of fill material 18a is that they are satisfactorily fused in the vertical direction to avoid delamination, and in most cases the fill material 18a is fused (melted, or cured) under ambient or room pressure.
However, in the case of vertically adjacent layers of composite swaths 2c (or even of composite swaths 2c neighboring fill material 18a in a vertical direction), more types and more complex interaction is required and/or enabled. The properties of a composite swath 2c, or especially a group of composite swaths 2c interacting with one another, may improve with significant compression (e.g., flattening to more than 1:4 proportion), and providing this compression in the part 14 may require accommodation of vertical and horizontal effects of the additional compression. In addition, unlike homogenous fill material 18a, the overlapping or crossing of composite swaths 2c may provide advantageous anisotropy or advantageous internal geometry.
With respect to additional compression, overlapping, or crossing, at least the following effects may be addressed:
1) Ironing compression is not necessarily linear, and because embedded fiber remains solidified and incompressible, compressed fiber may extend above or below the layer height of the fill material 18a within the same layers as the composite swaths 2c as set.
2) Overlapping or crossing composite swaths 2c may create humps 2c-3 or ridges 2c-4 that may extend above the current layer LAn height of the fill material 18a as set.
3) Overlapping or crossing composite swaths 2c-2, 2c-1 may cause a current or an underlying composite swath 2c-1 to widen (in which case air volume to receive the widening composite swath 2c-1 may be provided, modeled, marked, or calculated, and later filled with fill material 18a).
Note also that inter-layer effects may be of significantly lesser height than a layer LAn height of the slicing process for the fiber reinforced material and the fill material, for example, an intrusion of ⅔- 1/100 of the layer height. In those cases where the effect or intrusion is particularly small, e.g., ⅓- 1/100 of a layer height, it is not preferable to reslice the solid model at a fraction of the fill material layer height, as this may increase the printing time by a similar proportion. However, the effects may be “buffered” by, e.g., routing composite swaths 2c-1, 2c-2 in a neighboring layer to route around an inter-layer interference, or depositing fill material 18a to level the layer height LAn above or below an inter-layer interference 2c-3.
Accordingly, the present disclosure contemplates different buffering operations of an additive manufacturing 3D printer 100 to permit inter-layer effects of fiber compression, stacking, overlapping, crossing, and runout (e.g., different versions of composite swath 2c avoidance routing; different versions of composite swath 2c overprinting or fill material 18a “topping off”; ameliorating patterns which distribute rather than group discontinuities, gaps, or stress concentrations). In topping off, the controller 20 of the printer 1800 controls the actuators and the heaters to deposit at least one cover of fill material 18a (a material compatible with the matrix material 4a) or multi-strand core reinforced filament s in a layer adjacent the location at which the ironing force spreads the reinforcing strands 6a of the second consolidated composite swath 2c-2 against the first consolidated composite swath 2c-1, the cover having a thickness of less than the height HEIGHTNUM of the layer LAn.
In addition, the present disclosure contemplates that composite swath 2c routing and fill material 18a routing (i.e., toolpath generation) may generate data structures for keeping track of locations of inter-layer effects. One example data structure is an inter-layer interference map stored as a special set of zero-height contours (i.e., a zero-height phantom layer to which a layer above and below may refer during toolpathing operations). Contours may be stored in the interference map indicating the predicted effect in a layer above or below.
In depositing core reinforced filament as described in the CFF set of patent applications, the embedded strands 6a—unmelted carbon fiber, aramid, fiberglass, basalt or the like—are effectively incompressible and solid and cannot be as readily displaced as the heated and highly viscous fluidized thermoplastic 18a of FFF/FDM printing. The present disclosure details inventions, embodiments, and implementations of techniques for intra-layer and inter-layer crossing of core reinforced filament as applied in additive manufacturing in the CFF set of patent applications.
A core-reinforced multi-strand composite filament 2 may be supplied, for example, as a circular to oval cross section, and/or of approximately ⅓ mm in diameter and/or “13 thou” diameter.
As shown in Table 1 below, a circular cross-section filament 2 compressed during deposition becomes a progressively wider composite swath 2c. The table uses an example dimensionless diameter of 3 units for “round numbers”.
As shown in the table, for any size of substantially circular cross section core reinforced filament 2, flattening to about ⅓ of its diameter becomes about 2.2-2.5 times as wide as its original diameter, and if flattened to about ½ its diameter becomes about 1.4-1.7 times its original diameter.
For example, to complement an additive manufacturing layer height of 0.1 mm, a ⅓ mm diameter core reinforced filament 2 may be flattened to a composite swath 2c of roughly rectangular shape of proportion 1:6 through 1:12 (herein “highly compressed”), e.g., about 0.7-1.1 mm wide by about 0.07-0.12 mm high. One preferred ratio is roughly 1:9. Even higher compression may be possible, e.g., 1:12 to 1:20, but may demand significant system stiffness in the printer 100.
In contrast, to complement an additive manufacturing layer height of 0.2 mm, a ⅓ mm diameter core reinforced filament 2 may be flattened to a composite swath 2c of roughly rectangular shape of proportion 1:1.5 to 1:4 (herein “lightly compressed”), e.g., about a roughly rectangular shape of about 0.4-0.6 mm wide by about 0.2 mm high.
However, a fiber-embedded rectangular cross section of 1:1.5 to 1:3 is not as compressed or consolidated as one of 1:6 to 1.12 proportion, and in many cases, an relatively higher amount of consolidation is preferable to reduce voids and improve mingling of fibers in adjacent ranks 2c-2c or 2c-2d.
It should be noted that a supplied fiber reinforced filament 2 may have a constant cross-sectional area as supplied and as deposited (unless coextruded or supplemented); while a supplied FFF filament 18a has both a very different cross-sectional area as supplied and as deposited (having a much larger diameter as supplied), as well as variable cross-sectional area as deposited (having a bead size depending on extrusion rate). Given that a highly compressed composite swath is preferable to a lightly compressed one, combining a larger FFF extrusion rate layer height (e.g., 0.3 mm) with a highly compressed composite swath (e.g., 1:9 ratio) may be challenging. Accordingly, when a fill material height is such that the amount of compression is unacceptably reduced, more than one layer of fiber may be arranged per layer of fill material (e.g., 2 or 3 1:9 sublayers of 0.1 mm composite swath 2c per one respective 0.2 or 0.3 mm layer of fill material 118a). In this case, most or all fill material 18a is deposited after the composite swaths 2c; although in an alternative mode self-collision detection may be used to avoid contacting the nozzles to the part and the order of deposition thereby varied. In addition, in a modification of this process, the fill material height and compression amount may be selected to match stacks of 1:6-1:12 “highly compressed” composite swaths 2c (e.g., for a fiber of ⅓ mm diameter, the matching fill material 18a layer height capped at approximately 0.24 mm, because the highest acceptable “highly compressed” stack of two fibers is 1:6 ratio×2, or 0.12 mm×2).
As shown in
It should be noted that the cross-sectional representation of reinforcing strands 4a within filament 2a and deposited swaths 2c are schematic only. In most cases, the reinforcing strands are in the hundreds to thousands of parallel strands within the filament 2a or swaths 2c.
Disclosed herein are complementary toolpaths, composite swath deposition strategies, or reinforcement formations 99A-99Z—first, second, and other formations—for both composite swaths 2c and fill material 18a within layers and in adjacent layers, was well as overlaps within a layer, such as same-layer crossing turn overlaps and same-layer parallel overlaps. In addition, “smoothing over” and “attenuation” strategies within or adjacent reinforcement formations 99A-99Z avoid accumulation of, in particular, fiber material overlap protrusions over several or many layers. Such strategies can also be used to ameliorate accumulation of tolerance stack among many composite swath layers.
Using different formations may also permit horizontal repositioning of stress concentrations, gaps, or seams arising from fiber routing in the horizontal plane, as they may permit varying of positioning of start position, end positions, runout accumulation or shortfall, and sharp turns in the composite swath 2c. This is especially the case near contour boundaries, holes Ha, Hb, Hc, etc. or negative contours, as well as channels and island contours, as localized reinforcement in many cases means various sharp turns in the surrounding toolpath. Accordingly, a purpose of using different reinforcement formations within a layer and among layers is to distribute gaps, seams, and stress concentrations to positions that are different from locations in adjacent or nearby layers, and/or in distributed positions among layers; as well as to permit different kinds of reinforcements for different stresses to be distributed among layers.
For example, taking
As shown in
Different contour following strategies or reinforcement formations without internal overlaps or composite swath crossings within a layer may be layered among different layers. For example, the following strategy or reinforcement formation 99C of
As noted, individual reinforcement formation s 99A-99Z may be varied to vary distribution of isolated gaps, starting positions, end positions, and/or stress concentrations. Crossing points PR (i.e., crossing composite swaths within a same layer LAn may provide more flexibility in the design of toolpaths of reinforcement formations 99A-99Z, permitting more locations for seams to be distributed, as well as additional forms should seams tend to stack among layers LAn, LAn+1, etc., or. Overlaps PR of composite swaths 2c within a layer LAn may create stress concentrations as relatively sharp turns in the composite swath 2c upward and then downward are made, but with sufficient remelting, reduction in printing speed, feeding at a faster rate than the printing speed to provide, or compression in overprinting, these path changes or turns may permit added horizontal repositioning of stress concentrations arising from path planning in the horizontal plane, as well as avoiding turns in the composite swath leftward and rightward as the composite swath 2c is permitted to continue in a straight path 991. This is especially the case at crossing turns PR about holes and negative contours Ha, Hb, Hc etc., as reinforcement of a hole in most cases has an entrance and exit to the surrounding toolpath of fiber/composite swath 2c or reinforcement formation 99A-99Z, and the use of crossing turns can permit more freedom in locating that entrance/exit. Accordingly, a purpose of such crossing turns is to distribute gaps, starting and stopping positions, and stress concentrations to positions that are different from locations in adjacent or nearby layers LAn−1, LAn+1, and/or in distributed positions among layers LA1 . . . LAm; as well as to permit different reinforcements for different stresses to be distributed among layers. “Location” may mean in 2D or 3D location, along contours, or along stress or load lines or fields.
In an alternative, for a second type of material, the controller 20 of the printer 1000 has uses one or more of higher than straight path printing speed, higher than straight path nozzle tip compression, and/or slower than printing speed filament feed rate.
Continuous carbon fiber composite laminates may be formed up in a “quasi-isotropic” (QI) four-ply or three-ply construction at 0, +/−45 degrees, and 90 degrees. Anisotropically biased layups (e.g., 0, +/−30 degrees, 90 degrees) are also used. The laminae are cut at the row ends. The reinforcement formations discussed herein for 3D printed composite swaths 2c may optionally be used in combination with QI construction.
FDM or FFF layers may be formed in orthogonal layers at +/−45 degrees of alternating raster formation. Generally raster formation is preferred in order to extrude hot, flowing plastic next to still-warm extrudate from the immediately previous row to improve bonding, with only minor consideration for directional strength. The +/−45 degree raster formation gives a multi-directional and satisfactory workable middle range of tensile strength, +/−25% from the best and worst rastering patterns (e.g., 20 MPa UTS for ABS in 45-45 pattern, vs. about +5 MPa for longitudinal raster and about −5 MPa for transverse or diagonal raster). Note also that the better rastering patterns per load direction, which may place the direction of most of the extrudate roads in the same direction as the load, may approach injection molding strength (e.g., about 95% of injection molding).
In 3D printing in a stranded-filament-to-ironed swath 2c technique, both negative and positive contours may be reinforced beyond the matrix or fill material strength with continuous composite swaths looping about the contour without severing the fiber. This in-plane looping is impossible with composite layup, which cannot make turns within the plane without breaking the materials; and of different character and limited effect with extrudate.
In the case of one, two, or more holes, negative contours, embedded contours, or overmolded contours in an actual part, in many cases different kinds of reinforcement will be possible. For example:
(1) Reinforcement of inner walls and hole walls may closely follow the walls, with or without layers of fill material shielding the innermost wall to prevent print-through of fiber, e.g.,
(2) Reinforcement of outer walls may closely follow the walls, with or without layers of fill material shielding the innermost wall to prevent print-through of fiber, e.g.,
(3) Reinforcement may extend along load lines or stress lines, e.g.,
(4) Reinforcement for tension load purposes may include multiple straight composite swaths between the sites at which the tension load is supported, e.g.,
(5) Reinforcement for torsion, torque, or pressure load purposes may include multiple circular composite swaths along directions of hoop stresses, e.g.,
(6) Reinforcement for compression load purposes may include multiple neighboring composite swaths to provide low aspect ratio cross sections and/or squat structures, and/or anchors at ½, ⅓ fractional, e.g. harmonic lengths to guard vs. buckling; and/or e.g., more composite swaths for compression struts than for tension struts.
(7) Reinforcement for twisting may include angular cross bracing in triangle or X shapes, e.g.,
(8) Reinforcement for bending or combination load purposes may include embedded high moment of inertia (cross section) structures such as sandwich panels, tubes, boxes, I-beams, and/or trusses formed from embedded composite swaths. These may be made in layers spaced from the centroid of the part cross section, or in outer toolpaths spaced from the centroid of the part cross section, depending on the load and the orientation of the part during printing.
There are several possible mitigation/exploitation strategies, intra-layer and inter-layer, once toolpaths for composite swaths are overlapped or crossed.
In general, it is preferable to apply strategies in which compression and/or layer height interference of an overlapping or crossing layer (e.g., which may correspond in part to layer height) may be set to deposit two highly compressed layers of composite swaths 2c-2, 2c-1, and to square up corresponding fill material 18a at a height of close to twice the highly compressed composite swath height. It may also be preferable to permit or create crossings of toolpaths of composite swaths 2c-1, 2c-2, and to square up corresponding fill material 18a at a height of close to twice the highly compressed composite swath height. Crossings of highly compressed composite swaths with one another, and/or crossings of highly compressed composite swaths with lightly compressed composite swaths may be used. As shown in the CFF patent applications, toolpaths for deposition of core reinforced fiber may be generated within contours and sub-contours, and in order to maintain parallel paths, and often follow offsets of the contours and sub-contours.
It should be noted that only some toolpaths, composite swaths 2c, and/or multi-swath fiber tracks form “loops”, closed “loops”, or “crossing turns” as continuously deposited in a single layer LA1 of an additive manufacturing process. For example,
In this regard, as an alternative example, no buffer zone BF is shown in
As shown in
As noted, the second, inwardly spiraling reinforcement formation of
In either case, when printed together with the first formation 99I, the second formation 99P provides additional reinforcement for tensile loads between the two holes H1, H2, reinforced wall strength in compression or vs. impact or crushing for the outer walls of the eventual multi-layer (e.g., 100-1000 layer) link arm. Further, the second formation 99P provides additional moment of inertia in cross section, in two bending directions. For example, with respect to an X-Y-Z coordinate system with the XY plane parallel to the layer and the X axis along a lone joining the hole centers, as shown, a part having the second formation 99P printed in substantially top and bottom layers along the Z direction will have a higher moment of inertia vs. bending loads on the X-Y plane as well as bending loads on the ZY plane.
As shown in
In either case, when printed together with the first formation 99Q, the second formation 99R in
Crossing points made in a same layer, which may be one continuous composite swath or different composite swaths, may be referred to as “intra-layer” crossing points. Crossing points made between two layers, which in most cases may be different continuous composite swaths (one exception being the ABBA pattern of
Each of
As one example,
It should be noted that complementary patterns between two layers need not include a crossing point, jump, or crossing turn to have the benefits of the use of complementary patterns, or to maintain the amount of stacking at 2 composite swath thicknesses among 2 layers. The discussion herein of beneficial stacking of complementary patterns applies even to layers which do not cross composite swaths within the layer. For example,
As shown in
Each of
The controller 20 of the printer 1000, may, as described herein, supplying a multi-strand core reinforced filament 2 including a flowable matrix material 4a and a plurality of substantially continuous reinforcing strands 6a of a material having a tensile strength of greater than 300 MPa. The substantially continuous reinforcing strands 6a extend in a direction parallel to a length of the filament. As shown in
Optionally, within the same first layer LAn, the printer 1000 deposits a second consolidated composite swath 2c of a height less than ½ the width of the filament 2 in a second reinforcement formation 99Z2 including a second plurality of parallel lengths each extending a second direction angled from the first direction by sixty degrees, by flowing the matrix material 4a and applying an ironing force to spread the reinforcing strands 6a within the filament 2 against the first plurality of parallel lengths of the first consolidated composite swath 2c of the formation 99Z1. Subsequently, in a second layer LAn+1 above the first layer LAn, the printer 1000 may deposit a third consolidated composite swath 2c of a height less than ½ the width of the filament 2 in a third reinforcement formation 99Z3 including a third plurality of parallel lengths each extending a third direction angled from the first and second directions by sixty degrees, by flowing the matrix material 4a and applying an ironing force to spread the reinforcing strands 6a within the filament 2 against both the first and second pluralities of parallel lengths of the first and second consolidated composite swaths 2c, 2c of the formations 99Z1, 99Z2. The angle from the first formation of the second, third formations may alternatively be 120 degrees, 90 degrees, or other angles which divide evenly into 360 degrees.
Further optionally, as shown in
Alternatively, even in the case of fill material 18a only, the controller 20 of the printer 1000, may, supplying a filament including a flowable polymer material, and within a first layer LAn, deposit rows of the flowable polymer material 18a in a first reinforcement formation 99Z1 including a first plurality of parallel lengths each extending in a first direction by flowing the flowable polymer material 18a against a deposition surface 14, and within the same first layer LAn, deposit rows of the flowable polymer material 18a in a second reinforcement formation 99Z2 including a second plurality of parallel lengths each extending in a second direction angled from the first direction by sixty degrees, by flowing the flowable polymer material 18a against the deposition surface (at least in part the prior bead from formation 99Z1) and to thin out when the second plurality of parallel lengths crosses the first rows of the flowable polymer material. Within the same first layer LAn, the controller 20 may deposit rows of the flowable polymer material 18a in a third reinforcement formation including a third plurality of parallel lengths each extending in a third direction angled from the first and second directions by sixty degrees, by flowing the matrix material against the first rows of the flowable polymer material and to thin out when the third plurality of parallel lengths crosses the first and second pluralities of parallel lengths of the first two rows of the flowable polymer material.
This technique for fill material 18a also applies to composite swaths, e.g., in the case where supplying a filament further comprises supplying a multi-strand core reinforced filament 2 including a flowable polymer matrix material 4a and a plurality of substantially continuous reinforcing strands 6a of a material having a tensile strength of greater than 300 MPa as discussed herein, where each row of flowable polymer material is deposited as a consolidated composite swath 2c as discussed herein, and advantageously as the third plurality of parallel lengths is deposited with each parallel length offset from an intersection of the first and second consolidated parallel lengths.
The interaction of the reinforcement formations may be implemented on the slicer or toolpath planner. In this case, a computer or workstation executes instructions for generating three-dimensional toolpath instructions for a three dimensional printer. The computer receives a three-dimensional geometry such as a solid model, NURBS model, mesh or STL file. The computer slices the three-dimensional geometry into layers LA1 . . . LAm, and generates toolpath instructions to deposit consolidated composite swaths 2c by ironing strand reinforced composite filament 2 to form consolidated composite swaths 2c having reinforcing strands 6a spread out against a surface 14 or 2d. The computer generates toolpath instructions to deposit a first consolidated composite swath 2c according to a first single layer toolpath or reinforcement formation 99Z1 within a first layer of the layers LA1 . . . LAm; (note a layer designated LA1 herein need not be the first layer of the part; LA1 is rather the first layer of the set of layers under discussion, which may begin or end anywhere within the part 14. The computer may generate toolpath instructions to deposit a second consolidated composite swath 2c according to a second single layer toolpath or reinforcement formation 99Z2 within the same first layer, the second consolidated composite swath having a crossing point with the first consolidated composite swath within the same first layer LA1, and
Generate toolpath instructions to iron the second consolidated composite swath 2c to spread against the first consolidated composite swath 2c within the same first layer LA1.
With reference to
Further, with reference to
When toolpaths and composite swaths 2c within a single layer LA1 cross or overlap, the composite swaths 2c maintain a cross-section of substantially constant area. A protrusion PR upwards or sideways will generally be created (in some cases, downward when space permits). For tough continuous fiber materials (e.g., aramid), the overlap may be made at a similar speed/pressure to the current straight line printing speed. For strong but more brittle fiber materials (e.g., glass or carbon fiber), the overlap may be made a slower speed and/or less pressure. For example, the composite swath 2c deposition may be printed at from 0 to 1.0 layer heights above the previously printed layer), and/or with a briefly higher feed rate. The protrusion PR, will generally not be larger than a single swath 2c width or height.
At least the following strategies are available for accommodating the protrusion PR in a part 14 where layers LA1-LAm are nominally of a consistent height—for example, 0.1 mm height. These strategies would in many cases be applied during slicing and toolpath or reinforcement formation planning for the part 14, in part so that inter-layer accommodations may be made. Where the protrusion PR scale (e.g., height and/or width) is modeled/predicted/empirically known and stored as an absolute or relative value or a function of system variables, the overlap PR or a buffer zone BF larger than the overlap PR may be marked or planned in the current layer LAn.
(1) Subsequent path planning in the same layer (layer LAn may:
(a) avoid crossing the overlap within the same layer (e.g., layer LAn by planning toolpaths which do not cross the overlap, although the new toolpaths may form a crossing point, jump, crossed loop or crossing turn forming a new overlap).
(b) plan new toolpaths within the same layer (layer LAn separated by more than the buffer zone.
Subsequent or integrated path planning for a new, adjacent layer (LAn+1) adjacent to the layer in which protrusions are formed (layer LAn may:
(c) increase the previous layer height (of layer LAn in the overall slicing approach, and/or decrease the current layer height (of layer LAn+1). This is most applicable when no composite swaths, or composite swaths which do not cross and create protrusions, will be formed in the current layer.
(d) path plan composite swaths to avoid overlaps and/or buffer zones in the layer below (layer LAn);
(e) path plan a complementary or partner patterns in the current layer (LAn+1) which provide complementary functionality to a pattern in an adjacent or previous layer (layer LAn).
An example is proposed for the case of
In order to accommodate this crossing protrusion horizontally, individual composite swaths 2c may be deposited at a pitch having an increased spacing associated with the overlap, protrusion, or buffer zone.
In order to accommodate this crossing and/or overlapping protrusion PR in the vertical direction, different steps may be taken (separately or together):
For example, the slice height for the layer including the crossing protrusion(s), e.g., layer LAn may be set to twice the composite swath 2c height, e.g., in particular for fill material 18a, and the feed rate of fill material 18a lowered at the location of the crossing protrusions PR. In such a case, per the example above, the maximum height of stacked fiber 2c, 2c within the layer LAn would be roughly 0.17 mm, where much of the fiber 2c is deposited at 0.1 mm high. Accordingly, fill material 18a would be deposited at a height of 0.2 mm, with a possible lowering of fill material 18a feed rate in the location of the fiber stacks 2c, 2c or PR where the additional material should be only 0.03 mm on top of the fiber stack 2c, 2c or PR. In the adjacent layer, the slice height may be returned to the composite swath 2c height of 0.1 mm, and/or continued at 0.2 mm should additional crossing points or protrusions PR or 2c, 2c be anticipated or planned.
In another example, the slice height for the layer including the crossing protrusion, e.g., layer LAn is continued at the composite swath 2c height. In this case, any protrusions into layer LAn+1 may be marked, and layer LAn completed at the 0.1 mm height. Layer LAn+1 is planned such that the protrusions PR are considered already printed, and planning is completed considering the protrusions PR as to be avoided (e.g., as negative contours, or specially coded). In layer LAn+1, composite swaths 2c and fill material 18a may be considered differently. For example, the planning of composite swath 2c toolpaths and/or reinforcement formations may avoid the protrusions PR into the layer LAn+1 (to avoid accumulation of stacks of fiber 2c, 2c or PR), while the planning of fill material 18a toolpaths may fill at the location of protrusions PR. Again, the feed rate of fill material 18a may be lowered at the location of the crossing protrusions PR. In such a case, per the example above, the maximum protrusion of stacked fiber 2c, 2c into layer LAn+1 may be roughly 0.07 mm, where much of the fiber 2c is deposited in lower layer LAn at 0.1 mm high. Accordingly, fill material 18a would be deposited in layer LAn at a height of 0.1 mm, and in layer LAn+1 at a height of 0.1 mm, with a possible lowering of fill material 18a feed rate in the location of the protrusions PR where the additional material should be only 0.03 mm on top of the fiber stack 2c, 2c.
The controller 20 of the printer 1000, may, as described herein, receive toolpath instructions having a plurality of single layer toolpaths encoded with first and second degrees of freedom (e.g., a toolpath for composite swath 2c and/or fill material 18a, or a reinforcement formation 99A-99M). As noted, the printer 1000 may supply a strand reinforced composite filament 2 having reinforcing strands 6a embedded in a flowable matrix 4a. The printer 1000 may deposit consolidated (e.g., highly compressed) composite swaths 2c by both controlling the print head 10 to output the strand reinforced composite filament 2 with the reinforcing strands 6a oriented parallel to a trajectory of the print head 10, and controlling the print head 10 to iron the strand reinforced composite filament 2 to form consolidated composite swaths 2c having reinforcing strands 4a spread out against a surface 14 or 2d.
In order to overlap composite swaths 2c-2, 2c-1 one over another, whether in the same direction (parallel) and or in different directions (crossing), the printer 1000 may deposit a first consolidated composite swath 2c-1 according to a first single layer toolpath or reinforcement formation 99A-99Z within a first layer LAn, and deposit a second consolidated composite swath 2c-2 according to a second single layer toolpath or reinforcement formation 99A-99Z within the same first layer LAn, the second consolidated composite swath 2c-2 having a crossing point PR with the first consolidated composite swath 2c-1 within the same first layer LAn, while ironing the second consolidated composite swath 2c-2 to spread against the first consolidated composite swath 2c-1.
In a further refinement, variation, addition, or alternative to of this technique, the first and second single layer toolpaths or reinforcement formations 99A-99Z form a closed loop from the continuous strand reinforced composite filament 2c, and the first and second consolidated composite swaths 2c-1, 2c-2 form a crossing turn within the same first layer LAn. The closed loop and the crossing turn may be deposited in a location adjacent to and reinforcing a negative subcontour Ha, Hb, etc., within an interior of the same first layer LAn. The printer 1000 may deposit a third consolidated composite swath 2c in a location adjacent to and reinforcing the closed loop and crossing turn in one of the same first layer LAn or an adjacent second layer LAn+1 or LAn−1.
In an additional further refinement, variation, addition, or alternative to of this technique, the printer 1000 may, in order to control the print head 10 to iron the strand reinforced composite filament 2 to form consolidated composite swaths 2c having reinforcing strands spread out against a surface 14 or 2d, further flow the matrix material 4a, and apply an ironing force that spreads the reinforcing strands 6a, in a manner to
form consolidated composite swaths 2c of a height less than ½ the width of the strand reinforced composite filament 2 (e.g., as supplied in a roughly circular, square, or other roughly unitary aspect ratio cross-section).
In general, in the “FFF” or “FDM” extrusion method of additive manufacturing, extrusion beads in adjacent layers LAn, LAn+1 may be arranged to run either parallel or transverse to one another, without crossing while within a layer. A “retract” may be performed in the filament feed path to stop nozzle flow and move from one isolated area to another to restart extrusion, but the active printing beads tend to remain uncrossed. This is reasonable, because continuing to extrude while crossing a previously printed bead may cause extrudate to jet out horizontally and unpredictably as the nozzle is partially blocked. Additionally, any time spent extruding with a blocked nozzle reduces the amount of active deposition of extrusion. Slicing software generally avoids creating extrusion toolpaths which cross one another.
However, in the FFF printer discussed herein, extrusion toolpaths may cross one another in the same manner as described with respect to core reinforced fiber toolpaths, partially enabled by a fast-response clutching in the filament supply for the extrusion head 18, e.g., a low motor current or other slippable drive. In such a case, crossing extrusion toolpaths should cross at a high angle (e.g., from 45-90 degrees) and/or limited to short periods of time or narrow existing beads (e.g., for 1/10 to 1/100 of a second, e.g., for a printing extrusion speed of 300 mm/s, crossing no more than 1 mm of previously solidified extrudate, and preferably ¼ to ½ mm of solidified extrudate). This is particularly advantageous in the case of honeycomb fills of patterned lines (e.g., triangular tessellation, e.g., of 60-60-60 degree crossing straight paths, either with all paths intersecting [triangular honeycomb] or two paths intersecting with one path offset [Star of David network or honeycomb]).
Generally, even the fast-response buffered crossing of a newly extruded bead or road of fill material 18a across a previously printed extrusion bead or toolpath may not change the layer height of the current layer LAn either on top of the solidified bead crossed or in the currently deposited row, i.e., neat plastic does not generally vertically accumulate as beads are crossed. Rather, fluidized fill material 18a tends to find a least resistance direction to escape horizontally or downward when the extrusion nozzle 18 is blocked by a previously deposited bead.
A “fold” may refer to a composite swath 2c or part of a reinforcement formation 99A-99Z which folds, twists, or bunches over itself along a curved segment of composite swath 2c (such as a sharp corner, where a sharp corners is an unfolded or folded corners having a corner radius from 0 to twice the composite swath 2c width). As shown in
The controller 20 of the printer 1000, may, as described herein, supply a strand reinforced composite filament 2 including a flowable matrix material 4a and a plurality of substantially continuous reinforcing strands 6a of a fiber material having a tensile strength of greater than 300 MPa. The substantially continuous reinforcing strands 6a extend in a direction parallel to a length of the filament 2. The controller 20 of the printer 1000 may receive toolpath instructions having a plurality of single layer toolpaths and or a reinforcement formation 99A-99Z encoded with first and second degrees of freedom. The controller 20 of the printer 1000 may consolidate composite swaths 2c by controlling the print head 10 to iron the strand reinforced composite filament 2 to less than ½ the width of the strand reinforced composite filament 2 to form consolidated composite swaths 2c having reinforcing strands 6a spread out against a surface 14 or 2d.
The printer 1000 may deposit a first reinforcement formation 99A-99Z including a plurality of interconnected straight segments 991 and curved segments 992, and/or deposit a second reinforcement formation 99A-99Z including a plurality of interconnected straight segments 991 and curved segments 992, different from the first reinforcement formation 99a-99Z. On curved segments 992 which change a direction of a connected straight segment 991 by more than 45 degrees, the controller 20 of the printer 1000 may control the printhead 10 to deposit consolidated composite swaths 2c in a toolpath or trajectory that is different from the embedded path or trajectory of the consolidated composite swath 2c as it is actually deposited in the part 14.
In forming corners as shown in
In a further refinement, variation, addition, or alternative to of this technique, on curved segments 992 which change a direction of a connected straight segment 991 by more than 45 degrees, controlling the printhead 10 to deposit consolidated composite swaths 2c in a toolpath is a longer linear trajectory than the embedded path of the consolidated composite swath 2c. Optionally, on curved segments 992 which change a direction of a connected straight segment 991 by more than 45 degrees, the controller 20 of the printer may control the printhead 10 to deposit consolidated composite swath 2c in a toolpath (e.g., within a reinforcement formation 99A-99Z) that folds the consolidated composite swath 2c in a curved segment 992 of the consolidated composite swath 2c. Further optionally, alternatively, or in addition, on curved segments 992 which change a direction of a connected straight segment 991 by more than 45 degrees, the controller 20 of the printer 1000 may control the printhead 10 to deposit consolidated composite swaths 2c in a toolpath (e.g., within a reinforcement formation 99A-99Z) that folds the consolidated composite swath 2c by moving many fibers within the consolidated composite swath 2c from one lateral location to a displaced lateral location along a curved segment 992 of the consolidated composite path 2c, e.g., as shown in
Section headings used herein are dependent upon following content which they describe, and can only broaden the content described.
1. A “composite swath” or “composite swath” may refer to a deposited fiber-reinforced composite filament, having been compressed, consolidated and widened by ironing during deposition. Extending within the composite swath are a plurality of individual fibers, from 50-5000, preferably 100-2000, within a matrix material.
2. A “multi-swath track” may refer to a set of parallel swaths that generally follow parallel paths, although individual swaths may deviate to avoid obstacles or achieve reinforcement goals.
2. A “loop” or “crossed loop” may refer to a toolpath, composite swath, or multi-swath track that jumps or crosses over itself.
3. A “crossing turn” may be a “loop” that loops about a contour, to directly surround the contour, or surround the contour at an offset from walls formed of fill material. “Loops” and “crossing turns” are “underhand loops” unless otherwise described.
4. The generally diamond-shaped crossing of two bonded ranks or two composite swaths, including those occurring in a loop or crossing turn, may be described as a “crossing point”.
5. A “bight” or “open loop” may mean a curved section of toolpath or composite swath, generally curved in a manner in which the toolpath or composite swath does not touch itself upon return from the curve (at least locally).
6. A “touching loop” may refer to a curved toolpath or composite swath that loops back to touch itself.
7. A “fold” may refer to a composite swath which folds, twists, or bunches over itself along a curved segment of composite swath (such as a corner). As shown in
8. A “standing end” may refer to a portion of a fiber reinforced filament that remains undeposited, e.g., within the printhead or upstream.
9. A “running end” may refer to a terminal, distal, or cut end of the swath deposited within the part.
10. “Fill material” includes material that may be deposited in substantially homogenous form as extrudate, fluid, or powder material, and is solidified, e.g., by hardening, crystallizing, transition to glass, or curing, as opposed to the core reinforced filament discussed herein that is deposited as embedded and fused composite swaths, which is deposited in a highly anisotropic, continuous form. “Substantially homogenous” includes powders, fluids, blends, dispersions, colloids, suspensions and mixtures, as well as chopped fiber reinforced materials.
11. “Honeycomb” includes any regular or repeatable tessellation for sparse fill of an area (and thereby of a volume as layers are stacked), including three-sided, six-sided, four-sided, complementary shape (e.g., hexagons combined with triangles) interlocking shape, or cellular.
12. A “Negative contour” and “hole” are used herein interchangeably. However, either word may also mean an embedded contour (e.g., an embedded material or object) or a moldover contour (e.g., a second object with surfaces intruding into the layer).
13. “Outwardly spiraling” or “outwardly offsetting” meaning includes that a progressive tracing, outlining, or encircling is determined with reference to an innermost, generally negative or reference contour, not necessarily that the composite swath mush begin next to that contour and be built toward an outer perimeter. Once the toolpath is determined, it may be laid in either direction. Similarly, “inwardly spiraling” or “inwardly offsetting” means that the progressive tracing is determined with reference to an outer, generally positive contour.
14. “3D printer” meaning includes discrete printers and/or toolhead accessories to manufacturing machinery which carry out an additive manufacturing sub-process within a larger process. A 3D printer is controlled by a motion controller 20 which interprets dedicated G-code (toolpath instructions) and drives various actuators of the 3D printer in accordance with the G-code.
15. “Extrusion” may mean a process in which a stock material is pressed through a die to take on a specific shape of a lower cross-sectional area than the stock material. Fused Filament Fabrication (“FFF”), sometimes called Fused Deposition Manufacturing (“FDM”), is an extrusion process. Similarly, “extrusion nozzle” shall mean a device designed to control the direction or characteristics of an extrusion fluid flow, especially to increase velocity and/or restrict cross-sectional area, as the fluid flow exits (or enters) an enclosed chamber.
16. A “conduit nozzle” may mean a terminal printing head, in which unlike a FFF nozzle, there is no significant back pressure, or additional velocity created in the printing material, and the cross sectional area of the printing material, including the matrix and the embedded fiber(s), remains substantially similar throughout the process (even as deposited in bonded ranks to the part).
17. “Deposition head” may include extrusion nozzles, conduit nozzles, and/or hybrid nozzles.
18. “Filament” generally may refer to the entire cross-sectional area of an (e.g., spooled) build material, and “strand” shall mean individual fibers that are, for example, embedded in a matrix, together forming an entire composite “filament”.
19. “Alternating”, with respect to reinforcement regions, generally means in any regular, random, or semi-random strategy, unless the pattern is described, specified, or required by circumstances, for distributing different formations within or among layers. E.g., simple alternation (ABABAB), repeating alternation (AABBAABB), pattern alternation (ABCD-ABCD), randomized repeating groups (ABCD-CBDA-CDAB), true random selection (ACBADBCABDCD), etc.
20. “Shell” and “layer” are used in many cases interchangeably, a “layer” being one or both of a subset of a “shell” (e.g., a layer is an 2.5D limited version of a shell, a lamina extending in any direction in 3D space) or superset of a “shell” (e.g., a shell is a layer wrapped around a 3D surface). Shells or layers are deposited as 2.5D successive surfaces with 3 degrees of freedom (which may be Cartesian, polar, or expressed “delta”); and as 3D successive surfaces with 4-6 or more degrees of freedom. Layer adjacency may be designated using descriptive notations “LA1”, “LA2” or LAn, LAn+1”, etc., without necessarily specifying unique or non-unique layers. “LA1” may indicate the view shows a single layer, “LA2” indicating a second layer, and “LA1, LA2” indicating two layers superimposed or with contents of each layer visible. For example, in a top down view, either of “LA1, LA2, LA3” or “LAn, LAn+1, LAn+2” may indicate that three layers or shells are shown superimposed. “LA1, LA2 . . . LAm” may indicate an arbitrary number of adjacent layers (e.g., m may be 2, 10, 100, 1000, or 10000 layers).
20. Some representative Ultimate/Tensile Strength and Tensile/Young's Modulus values for reinforcing fibers, matrix materials, fill materials, and comparative materials are as follows:
This application claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional application Ser. No. 62/080,890 filed Nov. 17, 2014; and 62/172,021 filed Jun. 5, 2015, the disclosures of which are herein incorporated by reference in their entirety; and is a continuation-in-part of U.S. patent application Ser. No. 14/491,439 filed Sep. 19, 2014, the disclosure of which is herein incorporated by reference in its entirety. U.S. patent application Ser. No. 14/491,439 claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional application Ser. No. 61/880,129, filed Sep. 19, 2013; 61/881,946, filed Sep. 24, 2013; 61/883,440, filed Sep. 27, 2013; 61/902,256, filed Nov. 10, 2013, 61/907,431, filed Nov. 22, 2013; 61/804,235, filed Mar. 22, 2013; 61/815,531, filed Apr. 24, 2014; 61/831,600, filed Jun. 5, 2013; 61/847,113, filed Jul. 17, 2013, and 61/878,029, filed Sep. 15, 2013, the disclosures of which are herein incorporated by reference in their entirety; and is a continuation-in-part of each of U.S. patent application Ser. No. 14/222,318, filed Mar. 21, 2014; U.S. patent application Ser. No. 14/297,437, filed Jun. 5, 2014; and U.S. patent application Ser. No. 14/333,881 [now U.S. Pat. No. 9,149,988], filed Jul. 17, 2014; the disclosures of which are herein incorporated by reference in their entirety. This application also relates to U.S. patent application Ser. No. 14/944,088 entitled MULTILAYER FIBER REINFORCEMENT DESIGN FOR 3D PRINTING, by Abraham Lawrence Parangi, David Steven Benhaim, Benjamin Tsu Sklaroff, Gregory Thomas Mark, and Rick Bryan Woodruff, filed on even date herewith and incorporated herein by reference.
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| Number | Date | Country | |
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| 20160107379 A1 | Apr 2016 | US |
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| Parent | 14491439 | Sep 2014 | US |
| Child | 14944093 | US | |
| Parent | 14333881 | Jul 2014 | US |
| Child | 14491439 | US | |
| Parent | 14297437 | Jun 2014 | US |
| Child | 14333881 | US |
