U.S. patent application number 15/660289 was filed with the patent office on 2017-11-09 for seam concealment for three-dimensional models.
The applicant listed for this patent is Stratasys, Inc.. Invention is credited to Donald J. Holzwarth, Paul E. Hopkins.
Application Number | 20170320254 15/660289 |
Document ID | / |
Family ID | 43756867 |
Filed Date | 2017-11-09 |
United States Patent
Application |
20170320254 |
Kind Code |
A1 |
Hopkins; Paul E. ; et
al. |
November 9, 2017 |
SEAM CONCEALMENT FOR THREE-DIMENSIONAL MODELS
Abstract
A three-dimensional model built with an extrusion-based digital
manufacturing system, and having a perimeter based on a contour
tool path that defines an interior region of a layer of the
three-dimensional model, where at least one of a start point and a
stop point of the contour tool path is located within the interior
region of the layer.
Inventors: |
Hopkins; Paul E.; (Savage,
MN) ; Holzwarth; Donald J.; (Minnetonka, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Stratasys, Inc. |
Eden Prairie |
MN |
US |
|
|
Family ID: |
43756867 |
Appl. No.: |
15/660289 |
Filed: |
July 26, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13707884 |
Dec 7, 2012 |
9724866 |
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15660289 |
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12565397 |
Sep 23, 2009 |
8349239 |
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13707884 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 48/21 20190201;
B33Y 50/02 20141201; Y10T 428/24802 20150115; B29C 64/124 20170801;
B29C 2948/92076 20190201; B29C 64/118 20170801; G05B 19/4099
20130101; B29K 2081/06 20130101; B29K 2055/02 20130101; B29K
2079/085 20130101; B29C 2948/92409 20190201; B29C 48/09 20190201;
B29C 2948/92571 20190201; B29C 64/112 20170801; B29C 2948/92428
20190201; B29K 2025/00 20130101; Y10T 428/24777 20150115; B29K
2069/00 20130101; B29C 64/393 20170801; B33Y 10/00 20141201; B29C
64/171 20170801; B29K 2077/00 20130101; B29C 48/92 20190201; B33Y
50/00 20141201 |
International
Class: |
B29C 47/06 20060101
B29C047/06; G05B 19/4099 20060101 G05B019/4099; B29C 64/112
20060101 B29C064/112; B29C 64/171 20060101 B29C064/171; B33Y 50/02
20060101 B33Y050/02; B29C 47/92 20060101 B29C047/92 |
Claims
1. A three-dimension model built with an extrusion-based digital
manufacturing system, the three-dimension model comprising a
plurality of layers of an extruded material, wherein at least one
of the layers comprises: a perimeter of the extruded material, the
perimeter comprising a start point and a stop point; and an
interior region of the layer defined by the perimeter, wherein at
least one of the start point and the stop point is located within
the interior region of the layer.
2. The three-dimensional model of claim 1, wherein the location of
the at least one of the start point and the stop point is offset
from a centerline of the perimeter of the layer by a distance that
is greater than about 50% of a road width of the perimeter.
3. The three-dimensional model of claim 2, wherein the distance
ranges from greater than about 50% of the road width to about 200%
of the road width.
4. The three-dimensional model of claim 1, wherein the start point
and the stop point are each located within the interior region of
the layer.
5. The three-dimensional model of claim 1, wherein the locations of
the start point and the stop point define an arrangement selected
from the group consisting of an open-square arrangement, a
closed-square arrangement, an overlapped closed-square arrangement,
an open-triangle arrangement, a closed-triangle arrangement, a
converging-point arrangement, an overlapped-cross arrangement, and
combinations thereof.
6. The three-dimensional model of claim 1, wherein the perimeter
comprises at least one step-over arrangement between the start
point and the stop point.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This is a divisional application of U.S. patent application
Ser. No. 12/565,397, filed on Sep. 23, 2009, and entitled "SEAM
CONCEALMENT FOR THREE-DIMENSIONAL MODELS", the contents of which
are incorporated by reference in its entirety.
BACKGROUND
[0002] The present disclosure relates to direct digital
manufacturing systems for building three-dimensional (3D) models.
In particular, the present invention relates to techniques for
building 3D models with extrusion-based digital manufacturing
systems.
[0003] An extrusion-based digital manufacturing system (e.g., fused
deposition modeling systems developed by Stratasys, Inc., Eden
Prairie, Minn.) is used to build a 3D model from a digital
representation of the 3D model in a layer-by-layer manner by
extruding a flowable consumable modeling material. The modeling
material is extruded through an extrusion tip carried by an
extrusion head, and is deposited as a sequence of roads on a
substrate in an x-y plane. The extruded modeling material fuses to
previously deposited modeling material, and solidifies upon a drop
in temperature. The position of the extrusion head relative to the
substrate is then incremented along a z-axis (perpendicular to the
x-y plane), and the process is then repeated to form a 3D model
resembling the digital representation.
[0004] Movement of the extrusion head with respect to the substrate
is performed under computer control, in accordance with build data
that represents the 3D model. The build data is obtained by
initially slicing the digital representation of the 3D model into
multiple horizontally sliced layers. Then, for each sliced layer,
the host computer generates one or more tool paths for depositing
roads of modeling material to form the 3D model.
[0005] In fabricating 3D models by depositing layers of a modeling
material, supporting layers or structures are typically built
underneath overhanging portions or in cavities of objects under
construction, which are not supported by the modeling material
itself. A support structure may be built utilizing the same
deposition techniques by which the modeling material is deposited.
The host computer generates additional geometry acting as a support
structure for the overhanging or free-space segments of the 3D
model being formed. Consumable support material is then deposited
from a second nozzle pursuant to the generated geometry during the
build process. The support material adheres to the modeling
material during fabrication, and is removable from the completed 3D
model when the build process is complete.
SUMMARY
[0006] A first aspect of the present disclosure is directed to a
method for building a 3D model with an extrusion-based digital
manufacturing system. The method includes generating a contour tool
path that defines an interior region of a layer of the 3D model,
where the contour tool path comprises a start point and a stop
point, and where at least one of the start point and the stop point
is located within the interior region of the layer.
[0007] Another aspect of the present disclosure is directed to a
method for building a 3D model with an extrusion-based digital
manufacturing system, where the method includes receiving data
comprising tool paths for building a plurality of layers of the 3D
model. The method also includes extruding a material in a pattern
based on the tool paths to form a perimeter of the extruded
material for one of the layers of the 3D model, where the perimeter
has a start point and a stop point, and defines an interior region
of the layer, and where at least one of the start point and the
stop point is located within the interior region of the layer.
[0008] Another aspect of the present disclosure is directed to a 3D
model built with an extrusion-based digital manufacturing system.
The 3D model includes a plurality of layers of an extruded
material, where at least one of the layers includes a perimeter of
the extruded material, and where the perimeter has a start point
and a stop point. The layer also includes an interior region
defined by the perimeter, where at least one of the start point and
the stop point is located within the interior region of the
layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a front view of an extrusion-based digital
manufacturing system for building 3D models and support
structures.
[0010] FIG. 2 is a top view of a layer of a 3D model being built
with the extrusion-based digital manufacturing system.
[0011] FIG. 3 is an expanded view of section 3 taken in FIG. 2,
illustrating a seam of the layer with an open-square
arrangement.
[0012] FIG. 4 is a flow diagram of a method for generating data and
building a 3D model having concealed seams.
[0013] FIG. 5 is an alternative expanded view of section 3 taken in
FIG. 2, illustrating a seam of a first alternative layer with a
closed-square arrangement.
[0014] FIG. 6 is an alternative expanded view of section 3 taken in
FIG. 2, illustrating a seam of a second alternative layer with an
overlapped closed-square arrangement.
[0015] FIG. 7 is an alternative expanded view of section 3 taken in
FIG. 2, illustrating a seam of a third alternative layer with an
open-triangle arrangement.
[0016] FIG. 8 is an alternative expanded view of section 3 taken in
FIG. 2, illustrating a seam of a fourth alternative layer with a
closed-triangle arrangement.
[0017] FIG. 9 is an alternative expanded view of section 3 taken in
FIG. 2, illustrating a seam of a fifth alternative layer with a
converging-point arrangement.
[0018] FIG. 10 is an alternative expanded view of section 3 taken
in FIG. 2, illustrating a seam of a sixth alternative layer with an
overlapped-cross arrangement.
[0019] FIG. 11 is an alternative expanded view of section 3 taken
in FIG. 2, illustrating a seam of a seventh alternative layer with
a combined perimeter and raster pattern arrangement, where a start
point is located adjacent to the seam and a stop point is located
within an interior region.
[0020] FIG. 12 is an alternative expanded view of section 3 taken
in FIG. 2, illustrating a seam of an eighth alternative layer with
a combined perimeter and raster pattern arrangement, where start
and stop points are each located within an interior region.
[0021] FIG. 13 is an alternative expanded view of section 3 taken
in FIG. 2, illustrating a seam of a ninth alternative layer with an
crimped-square arrangement.
[0022] FIG. 14 is a top view of a tenth alternative layer of the 3D
model being built with the extrusion-based digital manufacturing
system.
[0023] FIG. 15 is an expanded view of section 15 taken in FIG. 14,
illustrating a seam of the tenth alternative layer with a step-over
arrangement.
[0024] FIG. 16 is an alternative expanded view of section 15 taken
in FIG. 14, illustrating a seam of an eleventh alternative layer
with a shortened step-over arrangement.
DETAILED DESCRIPTION
[0025] The present disclosure is directed to a method for building
3D models with deposition patterns that contain concealed seams. As
discussed below, the method involves adjusting the start point
and/or the stop point of a contour tool path of a 3D model layer to
one or more locations that are within an interior region of the
layer. This effectively conceals the seam that is formed at the
intersection of the starting and stop points, which can increase
the aesthetic and functional qualities of the resulting 3D
model.
[0026] The following discussion of 3D models with concealed seams
is made with reference to 3D models built with modeling materials
since consumers are generally more concerned about the aesthetic
and physical qualities of the intended 3D models, and are less
concerned about such qualities of the "support materials" used to
form support structures, which are typically removed and discarded.
However, the techniques for forming concealed seams may also be
used to form support structures having concealed seams. Thus, the
term "three-dimensional model" may apply to a 3D model built with a
modeling material and to a support structure built with a support
material.
[0027] FIG. 1 is a front view of system 10 in use with computer 12,
where system 10 is an extrusion-based digital manufacturing system
that may be used to build 3D models and/or support structures with
concealed seams. As shown, system 10 includes build chamber 14,
platen 16, gantry 18, extrusion head 20, and supply sources 22 and
24. Suitable extrusion-based digital manufacturing systems for
system 10 include fused deposition modeling systems developed by
Stratasys, Inc., Eden Prairie, Minn.
[0028] Build chamber 14 is an enclosed, heatable environment that
contains platen 16, gantry 18, and extrusion head 20 for building a
3D model (referred to as 3D model 26) and a corresponding support
structure (referred to as support structure 28). Platen 16 is a
platform on which 3D model 26 and support structure 28 are built,
and moves along a vertical z-axis based on signals provided from
controller 30. As discussed below, controller 30 directs the motion
of platen 16 and extrusion head 20 based on data supplied by
computer 12.
[0029] Gantry 18 is a guide rail system configured to move
extrusion head 20 in a horizontal x-y plane within build chamber 14
based on signals provided from controller 30. The horizontal x-y
plane is a plane defined by an x-axis and a y-axis (not shown in
FIG. 1), where the x-axis, the y-axis, and the z-axis are
orthogonal to each other. In an alternative embodiment, platen 16
may be configured to move in the horizontal x-y plane within build
chamber 14, and extrusion head 20 may be configured to move along
the z-axis. Other similar arrangements may also be used such that
one or both of platen 16 and extrusion head 20 are moveable
relative to each other.
[0030] Extrusion head 20 is supported by gantry 18 for building 3D
model 26 and support structure 28 on platen 16 in a layer-by-layer
manner, based on signals provided from controller 30. Accordingly,
controller 30 also directs extrusion head 20 to selectively deposit
the modeling and support materials based on data supplied by
computer 12. In the embodiment shown in FIG. 1, extrusion head 20
is a dual-tip extrusion head configured to deposit modeling and
support materials from supply source 22 and supply source 24,
respectively.
[0031] Examples of suitable extrusion heads for extrusion head 20
include those disclosed in LaBossiere, et al., U.S. Patent
Application Publication Nos. 2007/0003656 and 2007/00228590; and
Leavitt, U.S. Patent Application Publication No. 2009/0035405.
Alternatively, system 10 may include one or more two-stage pump
assemblies, such as those disclosed in Batchelder et al., U.S. Pat.
No. 5,764,521; and Skubic et al., U.S. Patent Application
Publication No. 2008/0213419. Furthermore, system 10 may include a
plurality of extrusion heads 18 for depositing modeling and/or
support materials.
[0032] The modeling material may be provided to extrusion head 20
from supply source 22 through pathway 32. Similarly, the support
material may be provided to extrusion head 20 from supply source 24
through pathway 34. System 10 may also include additional drive
mechanisms (not shown) configured to assist in feeding the modeling
and support materials from supply sources 22 and 24 to extrusion
head 20.
[0033] The modeling and support materials may be provided to system
10 in a variety of different media. For example, the modeling and
support materials may be provided as continuous filaments fed
respectively from supply sources 22 and 24, as disclosed in Swanson
et al., U.S. Pat. No. 6,923,634; Comb et al., U.S. Pat. No.
7,122,246; and Taatjes et al, U.S. Patent Application Publication
Nos. 2010/0096489 and 2010/0096485. Examples of suitable average
diameters for the filaments of the modeling and support materials
range from about 1.27 millimeters (about 0.050 inches) to about
2.54 millimeters (about 0.100 inches), with particularly suitable
average diameters ranging from about 1.65 millimeters (about 0.065
inches) to about 1.91 millimeters (about 0.075 inches).
Alternatively, the modeling and support materials may be provided
as other forms of media (e.g., pellets and resins) from other types
of storage and delivery components (e.g., supply hoppers and
vessels).
[0034] Suitable modeling materials for building 3D model 26 include
materials having amorphous properties, such as thermoplastic
materials, amorphous metallic materials, and combinations thereof.
Examples of suitable thermoplastic materials for ribbon filament 34
include acrylonitrile-butadiene-styrene (ABS) copolymers,
polycarbonates, polysulfones, polyethersulfones,
polyphenylsulfones, polyetherimides, amorphous polyamides, modified
variations thereof (e.g., ABS-M30 copolymers), polystyrene, and
blends thereof. Examples of suitable amorphous metallic materials
include those disclosed in U.S. patent application Ser. No.
12/417,740.
[0035] Suitable support materials for building support structure 28
include materials having amorphous properties (e.g., thermoplastic
materials) and that are desirably removable from the corresponding
modeling materials after 3D model 24 and support structure 26 are
built. Examples of suitable support materials for ribbon filament
34 include water-soluble support materials commercially available
under the trade designations "WATERWORKS" and "SOLUBLE SUPPORTS"
from Stratasys, Inc., Eden Prairie, MN; break-away support
materials commercially available under the trade designation "BASS"
from Stratasys, Inc., Eden Prairie, MN, and those disclosed in
Crump et al., U.S. Pat. No. 5,503,785; Lombardi et al., U.S. Pat.
Nos. 6,070,107 and 6,228,923; Priedeman et al., U.S. Pat. No.
6,790,403; and Hopkins et al., U.S. Patent Application Publication
No. 2010/0096072.
[0036] Prior to a build operation, computer 12 may receive a
digital representation of 3D model 26. Computer 12 is one or more
computer-based systems that communicates with system 10 (e.g., with
controller 30), and may be separate from system 10, or
alternatively may be an internal component of system 10. Upon
receipt of the digital representation of 3D model 26, computer 12
may reorient the digital representation and generate one or more
supports for any overhanging regions that require vertical support
(e.g., with support structure 28).
[0037] Computer 12 may then slice the digital representation and
generated supports into multiple layers. For each layer, computer
12 may then generate one or more tool paths for extrusion head 20
to follow for building each layer of 3D model 26 and support
structure 28.
[0038] The generation of the tool path(s) for a layer of 3D model
26 may initially involve generating one or more contour tool paths
that define the perimeter(s) of 3D model 26 for the given layer. As
discussed below, computer 12 also desirably adjusts the start point
and/or the stop point of each contour tool path of the layer to one
or more locations that are within an interior region of the layer
defined by the respective contour tool path. This effectively
conceals the seam that is formed at the intersection of the start
and stop points.
[0039] Based on each generated contour tool path, computer 12 may
then generate one or more additional tool paths (e.g., raster
paths) to fill in the interior region(s) defined by the
perimeter(s), as necessary. As further discussed below, the
generation of the additional tool path(s) (e.g., raster paths)
desirably compensate for the adjustments in the locations of the
start points and/or the stop points of the contour tool
path(s).
[0040] One or more tool paths for the layer of support structure 28
may also be generated in the same manner. This process may then
repeated be for each sliced layer of the digital representation,
and the generated data may be stored on any suitable computer
storage medium (e.g., on a storage device of computer 12). The
generated data may also be transmitted from computer 12 to
controller 30 for building 3D model 26 and support structure
28.
[0041] During a build operation, controller 30 directs one or more
drive mechanisms (not shown) to intermittently feed the modeling
and support materials to extrusion head 20 from supply sources 22
and 24. For each layer, controller 30 then directs gantry 18 to
move extrusion head 20 around in the horizontal x-y plane within
build chamber 14 based on the generated tool paths. The received
modeling and support materials are then deposited onto platen 16 to
build the layer of 3D model 26 and support structure 28 using the
layer-based additive technique.
[0042] The formation of each layer of 3D model 26 and support
structure 28 may be performed in an intermittent manner in which
the modeling material may initially be deposited to form the layer
of 3D model 26. Extrusion head 20 may then be toggled to deposit
the support material to form the layer of support structure 28. The
reciprocating order of modeling and support materials may
alternatively be used. The deposition process may then be performed
for each successive layer to build 3D model 26 and support
structure 28. Support structure 28 is desirably deposited to
provide vertical support along the z-axis for overhanging regions
of the layers of 3D model 26. After the build operation is
complete, the resulting 3D model 26/support structure 28 may be
removed from build chamber 14, and support structure 28 may be
removed from 3D model 26.
[0043] FIGS. 2 and 3 illustrate layer 36, which is a layer of 3D
model 26 formed by depositing a modeling material with system 10.
As shown in FIG. 2, layer 36 includes perimeter path 38, which is a
road of a modeling material that is deposited by extrusion head 20
along contour tool path 40. As discussed above, contour tool path
40 may be generated by computer 12 based on road width 42, which is
a predicted width of a deposited road of the modeling material, and
may depend on a variety of factors, such as modeling material
properties, the type of extrusion-based digital manufacturing
system used, extrusion conditions, extrusion tip dimensions, and
the like. Suitable widths for road width 42 range from about 250
micrometers (about 10 mils) to about 1,020 micrometers (about 40
mils), with particularly suitable widths ranging from about 380
micrometers (about 15 mils) to about 760 micrometers (about 30
mils).
[0044] In the current example, the modeling material is deposited
along contour tool path 40 in a clockwise direction, as represented
by arrows 44, to form perimeter path 38. Alternatively, the
modeling material may be along contour tool path 40 in a
counter-clockwise direction. Perimeter path 38 includes exterior
surface 46 and interior surface 48, which are each offset from
contour tool path 40 by about one-half of road width 42. Exterior
surface 46 is the outward-facing surface of perimeter path 38 and
may be observable when 3D model 26 is completed. Interior surface
48 is the inward-facing surface of perimeter path 38, which defines
interior region 50. Interior region 50 is the region of layer 36
confined within perimeter path 38, and may be filled with
additional modeling material deposited along additionally generated
tool paths (e.g., raster paths, not shown).
[0045] As shown in FIG. 3, contour tool path 40 includes start
point 52 and stop point 54, where start point 52 is a first
location in the x-y plane at which extrusion head 20 is directed to
begin depositing the modeling material, and stop point 54 is a
second location in the x-y plane at which extrusion head 20 is
directed to stop depositing the modeling material. Accordingly,
during the build operation, controller 30 directs extrusion head 20
to begin depositing the modeling material at start point 52, and to
move along contour tool path 40 in the direction of arrow 56 until
reaching point 58. Extrusion head 20 is then directed to follow the
ring-geometry of contour tool path 40, as illustrated by arrows 44,
until reaching point 60. Extrusion head 20 is then directed to move
along contour tool path 40 in the direction of arrow 62 until
reaching stop point 54, where extrusion head 20 stops depositing
the modeling material.
[0046] This process provides a continuous road of the deposited
modeling material at all locations around perimeter path 38 except
at the intersection between points 58 and 60, where the outgoing
and incoming roads meet. This intersection forms a seam for layer
36 (referred to as seam 64). As shown, start point 52 and stop
point 54 are each located at an offset location from seam 64 within
interior region 50. This is in comparison to start and stop points
generated under a conventional data generation technique, in which
the start and stop points would typically be collinear with the
outer ring of contour tool path 40 (i.e., at points 58 and 60,
respectively). Under the conventional technique, a contour tool
path is typically generated to match the geometry of the exterior
perimeter of a 3D model layer, with an offset that accounts for the
road width (e.g., road width 42). Thus, the start and stop points
would necessarily be located at locations that are collinear with
the contour tool path, and the stop point would end up being
located next to the start point (e.g., at points 58 and 60).
[0047] Due to variations in the extrusion process when starting and
stopping the depositions, the modeling material deposited at a stop
point corresponding to point 60 may bump into the modeling material
previously deposited at a start point corresponding to point 58.
This bumping can form a significant bulge of the modeling materials
at the seam, which can be visually observed with the naked eye,
thereby detracting from the aesthetic qualities of the resulting 3D
model. Alternatively, if not enough modeling material is deposited
between points 58 and 60, a gap may be formed at the seam, which
can increase the porosity of the 3D model. The increased porosity
can allow gases and fluids to pass into or through the 3D model,
which may be undesirable for many functional purposes (e.g., for
containing liquids). Accordingly, under the conventional data
generation technique, proper seam sealing may be difficult to
achieve, particularly due to the number of geometric complexities
that may be required for a given 3D model.
[0048] Pursuant to the method of the present disclosure, however,
seam 64 may be properly sealed by adjusting the location of the
start point from point 58 to point 52, and by adjusting the
location of the stop point from point 60 to point 54. This allows
any variations in the extrusion process when starting and stopping
the depositions to occur at a location that is within interior
region 50 rather than adjacent to exterior surface 46. Any
variations (e.g., bulges) that occur within interior region 50 are
masked by the successive layers of 3D model 26, thereby concealing
these effects within the filled body of 3D model 26 when completed.
This allows the dimensions of perimeter path 38 at seam 64 to be
truer to the dimensions of the digital representation of 3D model
26 and increases the consistency of the seams of successive layers
of 3D model 26.
[0049] While shown at particular x-y coordinates within interior
region 50, start point 52 and/or stop point 54 may alternatively be
adjusted to a variety of different coordinate locations within
interior region 50. Additionally, the coordinate locations may vary
depending on the dimensions of the particular layer of the 3D model
being built. In the embodiment shown in FIG. 3, start point 52 and
stop point 54 are adjusted respectively from points 58 and 60 by
vectors that are orthogonal to contour tool path 40 at perimeter
path 38, and which point toward interior region 50. Examples of
suitable distances for adjusting start point 52 from point 58
and/or for adjusting stop point 54 from point 60 (i.e., from a
centerline of perimeter path 38) includes distances that are
greater than 50% of road width 42 (i.e., beyond interior surface
48), with particularly suitable distances ranging from greater than
about 50% of road width 42 to about 200% of road width 42, and with
even more particularly suitable distances ranging from about 75% of
road width 42 to about 150% of road width 42.
[0050] The locations of start point 52 and stop point 54 also allow
the deposited modeling material to form a seal at seam 64 that
extends inward within interior region 50. This reduces the porosity
of 3D model 26 at seam 64, thereby reducing or eliminating the
transmission of gases and/or liquids through seam 64. As a result,
in comparison to the conventional techniques, the process of
adjusting the start and stop points to locations within interior
region 50 effectively eliminates the formation of bulges of
modeling material at seam 64, while also reducing the porosity at
seam 64.
[0051] FIG. 4 is a flow diagram of method 66 for generating data
and building a 3D model based on a digital representation of the 3D
model, where the resulting 3D model includes concealed seams. The
following discussion of method 66 is made with reference to 3D
model 26 (shown in FIG. 1) and layer 36 of 3D model 24 (shown in
FIGS. 2 and 3). However, method 66 is applicable for building 3D
models and corresponding support structures having a variety of
different geometries. As shown in FIG. 4, method 66 includes steps
68-84, and initially involves receiving a digital representation of
3D model 24 (step 68), slicing the digital representation and into
multiple layers (step 70), and generating one or more pre-sliced
support structures with computer 12 (step 72). In an alternative
embodiment, steps 70 and 72 may be reversed such that one or more
support structures are generated and the digital representation and
the generated support structure(s) are then sliced.
[0052] Computer 12 then selects a first layer of the sliced layers
and generates one or more contour tool paths based on the perimeter
of the layer (step 74). For example, computer 12 may generate a
contour tool path that defines the outer ring for perimeter path
38. In alternative examples, a given layer may include multiple
contour tool paths for building multiple and separate parts and/or
may include an exterior and an interior contour tool path for a
single part (e.g., having a hollow interior cavity). At this point,
the start and stop points for each generated contour tool path are
collinear with the perimeter of the layer.
[0053] Computer 12 may then adjust the locations of the start point
and/or the stop point to coordinate locations that are within the
interior region for each generated contour tool path (step 76). For
example, computer 12 may adjust the start point from point 58 to
point 52, and may adjust the stop point from point 60 to point 54.
This places start point 52 and stop point 54 within interior region
50. In an alternative embodiment, steps 74 and 76 of method 66 may
be performed in a single step. In this embodiment, the adjustment
locations of the start and stop points may be generated along with
the generation of the contour tool path(s) (e.g., as predefined
offset locations).
[0054] After the start and stop points are positioned in the
interior region of the layer (e.g., within interior region 50 of
layer 36), computer 12 may then generate additional tool paths
(e.g., raster paths) to bulk fill the interior region (step 78). In
this step, the generated additional tool paths desirably account
for the locations of start point 52 and stop point 54, and the
segments of contour tool path 40 that extend into interior region
50. When the layer is completed, computer 12 may then determine
whether the current layer is the last of the sliced layers (step
80). In the current example, layer 36 is not the last layer. As
such, computer 12 may select the next layer (step 82) and repeat
steps 74-82 until the last layer is completed.
[0055] When the last layer is completed, computer 12 may transmit
the resulting data to system 10 for building 3D model 26 and
support structure 28 (step 84). During the build operation,
extrusion head 20 follows the patterns of the tool paths for each
layer, including the contour tool paths with the adjusted start and
stop points. As such, each layer of 3D model 26 and/or of support
structure 28 may include a concealed seam having start and stop
points located within the interior region of the given layer.
Furthermore, the seams of adjacent layers may be offset from each
other, thereby further obscuring the locations of the seams.
[0056] FIGS. 5-13 are alternative sectional views of section 3
shown in FIG. 2, illustrating layers 136-936, which are
alternatives to layer 36 (shown in FIGS. 2 and 3) having different
start and stop points, and where the references labels are
increased by 100-900, respectively. As shown in FIG. 5, layer 136
includes contour tool path 140 having start point 152 and stop
point 154 in a closed-square arrangement. In this embodiment, start
point 152 is positioned at the same coordinate location within
interior region 150 as start point 52 (shown in FIG. 3). The
location of stop point 154, however, causes contour tool path 140
to turn at corner point 186. As such, contour tool path 140 extends
inward from point 160 in the direction of arrow 162, and turns in
the direction of arrow 188 at corner point 186 toward stop point
154. This arrangement further reduces the porosity of layer 136 by
creating a bend of the deposited roads of build material within
interior region 150.
[0057] As shown in FIG. 6, layer 236 includes contour tool path 240
having start point 252 and stop point 254 in an overlapped
closed-square arrangement. In this embodiment, start point 252 and
stop point 254 are positioned at the same coordinate location
within interior region 250 (i.e., stop point 254 overlaps start
point 252). This arrangement also includes corner point 286, which
bends contour tool path 240 in the same manner as discussed above
for corner point 186 (shown in FIG. 5), which is beneficial for
reducing porosity while also concealing seam 264.
[0058] The embodiment shown in FIG. 6 may be performed by gradually
increasing the volumetric flow rate of the modeling material as
extrusion head 20 travels between start point 252 and point 258,
and also by gradually reducing the reducing the volumetric flow
rate of the modeling material as extrusion head 20 travels between
point 260 and stop point 254. For example, when extrusion head 20
travels along contour tool path 240 between start point 252 and
point 258 in the direction of arrow 256, controller 30 may direct
extrusion head 20 to gradually increase the volumetric flow rate
from zero up to 100% of the standard operational rate. Extrusion
head 20 may then deposit the modeling material at 100% of the
standard operational rate while forming perimeter path 238 along
arrows 244. Then, when extrusion head 20 travels along contour tool
path 240 between point 260 and stop point 254 in the directions of
arrows 262 and 288, controller 30 may direct extrusion head 20 to
gradually reduce the volumetric flow rate from 100% of the standard
operational rate down to zero. This process reduces the amount of
modeling material that is accumulated along the vertical z-axis at
the intersection of start point 252 and stop point 254.
[0059] As shown in FIG. 7, layer 336 includes contour tool path 340
having start point 352 and stop point 354 in an open-triangle
arrangement. In this embodiment, start point 352 and stop point 354
extend at angles relative to the orthogonal directions of start
point 52 and stop point 54 (shown in FIG. 3). In this embodiment,
the corner points that direct contour tool path 340 into and out of
interior region 350 (i.e., points 358 and 360) are desirably offset
from each other by a distance that is about 90% of road width 342
to about 100% of road width 342. This allows seam 364 to be
properly sealed at exterior surface 346 of perimeter path 338.
[0060] As shown, start point 352 is positioned at a coordinate
location within interior region 350 that is offset at angle a from
the orthogonal axis to contour tool path 340 at perimeter path 338
(i.e., taken at point 358). Similarly, stop point 354 is positioned
at a coordinate location within interior region 350 that is offset
at angle .beta. from the orthogonal axis to contour tool path 340
at perimeter path 338 (i.e., taken at point 360). Angles .alpha.
and .beta. may be the same values from their respective orthogonal
axis, or may be different values, which may be affected by the
geometry of layer 336. Examples of suitable angles for each of
angle .alpha. and angle .beta. range from zero degrees (i.e.,
parallel to the orthogonal axis, as shown in FIG. 3) to about 60
degrees, with particularly suitable angles ranging from about 30
degrees to about 45 degrees. The angled locations of start point
352 and stop point 354 reduce the extent that start point 352 and
stop point 354 extend into interior region 350. This is arrangement
suitable for use with 3D models having thin-walled regions.
[0061] As shown in FIG. 8, layer 436 includes contour tool path 440
having start point 452 and stop point 454 in a closed-triangle
arrangement. In this embodiment, start point 452 extends at an
angle relative to the orthogonal direction of start point 52 (shown
in FIG. 3) in a similar manner to that discussed above for start
point 352 (shown in FIG. 7). Furthermore, this arrangement includes
corner point 486, which bends contour tool path 440 in a similar
manner to that discussed above for corner point 186 (shown in FIG.
5). This combination further reduces porosity, and also further
reduces the extent that start point 452 and stop point 454 extend
into interior region 450. As such, this embodiment is also suitable
for use with 3D models having thin-walled regions.
[0062] As shown in FIG. 9, layer 536 includes contour tool path 540
having start point 552 and stop point 554 in a converging-point
arrangement. In this embodiment, start point 352 and stop point 354
are positioned closer to each other compared to points 558 and 560.
The corner points that direct contour tool path 540 into interior
region 550 (i.e., points 558 and 560) are also desirably offset
from each other by a distance about equal to the road width of
perimeter path 538. As such, start point 552 and stop point 554 are
offset from each other by a distance that is less than the road
width.
[0063] This embodiment may be performed by gradually increasing the
volumetric flow rate of the modeling material as extrusion head 20
travels along contour tool path 540 in the direction of arrow 556
between start point 552 and point 558. Similarly, as extrusion head
20 travels along contour tool path 540 in the direction of arrow
562 between point 560 and stop point 554, the volumetric flow rate
may gradually decrease. This allows proper amounts of modeling
material to be deposited at seam 564 and also reduces the amount of
modeling material that is accumulated along the vertical z-axis at
the intersection between start point 552 and stop point 554.
[0064] As shown in FIG. 10, layer 636 includes contour tool path
640 having start point 652 and stop point 654 in an
overlapped-cross arrangement. In this embodiment, the relative
locations of start point 652 and stop point 654 cause contour tool
path 640 to overlap at seam 664. This embodiment may also be
performed by gradually adjusting the volumetric flow rate of the
modeling material as extrusion head 20 travels along contour tool
path 640. For example, the volumetric flow rate may be decreased
from 100% of the standard operational rate at point 660 down to
zero at stop point 654. However, in this embodiment, it is
desirable for the volumetric flow rate of the modeling material to
be substantially decreased at or shortly after point 660 to reduce
the amount of modeling material that is accumulated along the
vertical z-axis a seam 664.
[0065] Accordingly, during a build operation, extrusion head 20 may
initially follow contour tool path 640 from start point 652 to
point 658 in the direction of arrow 656. The volumetric flow rate
of the modeling material may also be gradually increased at this
stage. Extrusion head 20 may then deposit the modeling material at
100% of the standard operational rate while forming perimeter path
638 along arrows 644. Then, extrusion head 20 travels along contour
tool path 640 in the direction of arrow 662 between point 660 and
stop point 654, overlapping the previously deposited modeling
material. As such, as extrusion head 20 travels in the direction of
arrow 662, the volumetric flow rate may be decreased to reduce the
amount of modeling material that is accumulated along the vertical
z-axis at seam 664. The overlapping arrangement shown in FIG. 10
further reduces porosity by effective overlapping the intersection
at seam 664. In additional embodiments, contour tool path 640 may
further bent within interior region 650 to position stop point 654
at or adjacent to start point 652, as discussed above for the
embodiments of layers 136 and 236 (shown in FIGS. 5 and 6,
respectively).
[0066] FIGS. 11 and 12 illustrate additional alternative
embodiments in which the contour tool path also functions as an
interior raster path to fill at least a portion of the interior
region. As shown in FIG. 11, layer 736 includes contour tool path
740 having start point 752 located adjacent to exterior surface
746. As such, in this embodiment, start point 752 is not adjusted
to a location within interior region 750. However, the stop point
of contour tool path 740 (not shown) is adjusted to a location
within interior region 750 and contour tool path 740 is generated
to at least partially fill interior region 750 with a raster
pattern.
[0067] During a build operation, extrusion head 20 initially
follows contour tool path 740 from start point 752 in the direction
of arrow 744 to form perimeter path 738. Upon reaching point 760,
extrusion head 20 then turns and follows contour tool path 740 in
the direction of arrow 762 and continues to deposit the modeling
material in a back-and-forth raster pattern within interior region
750. This embodiment is beneficial for reducing the number of times
that a tip of extrusion head 20 needs to be picked up and moved.
Since this process can be performed with each layer of 3D model 26
and support structure 28, this can provide substantial time savings
when building 3D model 26 and support structure 28 in system
10.
[0068] Additionally, start point 752 and the stop point for contour
tool path 740 may also be positioned at locations in the x-y plane
that will maximize the area of interior region 750 that is filled
with the raster pattern of contour tool path 740. For example,
after generating contour tool path 740, pursuant to step 74 of
method 66 (shown in FIG. 4), the start and stop points may be
repositioned around the perimeter to a point that maximizes the
raster pattern fill within interior region 750 before reaching the
stop point. This further reduces the number of times that a tip of
extrusion head 20 needs to be picked up and moved for building each
layer. Furthermore, the generated raster pattern for contour tool
path 740 may be offset by an angle between each successive layer
(e.g., by 90 degrees). As a result, repositioning the start and
stop points in this manner will cause the seams of each successive
layer to be positioned at different locations in the x-y plane.
This further conceals the seams of a 3D model (e.g., 3D model 26)
by staggering the locations of the seams between successive
layers.
[0069] As shown in FIG. 12, layer 836 includes contour tool path
840 having both start point 852 and the stop point (not shown)
located within interior region 850, where contour tool path is
generated to at least partially fill interior region 850 with a
raster pattern, as discussed above for layer 736 (shown in FIG.
11). In the embodiment shown in FIG. 12, however, start point 852
is also located within interior region 850, desirably at an angle
that substantially follows the raster pattern of contour tool path
840. This combines the process time savings attainable with the
integrated raster pattern along with the reduced porosity that is
achieved by positioning start point 852 within interior region 850.
These benefits are in addition to the concealment of seam 864,
which allows the dimensions of perimeter path 838 at seam 864 to be
truer to the dimensions of the digital representation of 3D model
26 and increases the consistency of the seams of successive layers
of 3D model 26.
[0070] As shown in FIG. 13, layer 936 includes contour tool path
940 having start point 952 and stop point 94 in a crimped-square
arrangement. In this embodiment, start point 952 is positioned
within interior region 950 such that contour tool path 940 turns at
corner points 986a and 986b. During a build operation, extrusion
head 20 initially follows contour tool path 940 from start point
952 in the direction of arrows 956a, 956b, and 956c, until it
reaches point 958. Extrusion head 20 may form perimeter path 938
along arrows 944 until it reaches point 960. Extrusion head 20 may
then turn inward until it reaches stop point 954. In an alternative
embodiment, start point 952 and stop point 954 may be flipped such
that the crimped square geometry is formed around start point 952.
The arrangement depicted in FIG. 13 positions start point 952 and
stop point 954 within interior region 950, while also further
reducing the porosity of layer 936 by crimped square of the
deposited roads of build material within interior region 950.
[0071] FIGS. 14 and 15 illustrate layer 1036, which is an
additional alternative to layer 36 (shown in FIGS. 2 and 3), where
the reference labels are increased by 1000. As shown in FIG. 14,
layer 1036 includes perimeter paths 1038a and 1038b, which are a
pair roads of a modeling material that is deposited by extrusion
head 20 along contour tool path 1040 in two passes, as represented
by arrows 1044 (first pass to form perimeter path 1038a) and arrows
1090 (second pass to form perimeter path 1038b). As further shown,
perimeter path 1038a includes exterior surface 1046 and perimeter
path 1038b includes interior surface 1048. Exterior surface 1046 is
the outward-facing surface of perimeter path 1038a, which may be
observable when 3D model 26 is completed. Interior surface 1048 is
the inward-facing surface of perimeter path 1038b, which defines
interior region 1050. Interior region 1050 is the region of layer
1036 confined within perimeter paths 1038a and 1038b, and may be
filled with additional modeling material deposited along
additionally generated tool paths (e.g., raster paths, not
shown).
[0072] As shown in FIG. 15, contour tool path 1040 includes start
point 1052 and stop point 1054, where stop point 1054 is located
within interior region 1050. Accordingly, during the build
operation, controller 30 directs extrusion head 20 to begin
depositing the modeling material at start point 1052, and to move
along contour tool path 1040 in the direction of arrows 1044 until
reaching point 1092. This substantially forms perimeter path 1038a.
At this point, while continuing to deposit the modeling material,
extrusion head 20 steps over from perimeter path 1038a to begin
forming perimeter path 1038b at point 1094. Extrusion head 20 then
continues to moves along contour tool path 1040 in the direction of
arrows 1090 until reaching stop point 1054. This forms perimeter
path 1038b.
[0073] As shown, stop point 1054 is adjusted to a location within
interior region 1050. As such, seam 1064 also extends inward within
interior region 1050. This effectively eliminates the formation of
bulges of modeling material at seam 1064. Additionally, the
step-over arrangement also reduces the porosity of 3D model 26 at
seam 1064, thereby reducing or eliminating the transmission of
gases and/or liquids through seam 1064.
[0074] In an alternative embodiment, start point 1052 and stop
point 1054 may be flipped such that start point 1052 is located
within interior region 1050. In this embodiment, when extrusion
head 20 reaches stop point 1054 (at the location of start point
1052 in FIG. 15), extrusion head 20 may step back again toward the
location of stop point 1054 in FIG. 15, thereby creating an
X-pattern at seam 1064. The volumetric flow rate of the modeling
material is desirably reduced when stepping back again to reduce
the amount of the modeling material that is accumulated along the
vertical z-axis at seam 1064.
[0075] In additional alternative embodiments, the step-over
arrangement may be continued to form additional perimeter paths
1038, thereby increasing the overall thickness of the perimeter
paths. These embodiments are beneficial for use with thin-walled
regions where the formation of raster patterns may be more time
consuming. Furthermore, the embodiments discussed in FIGS. 14 and
15 may be combined with the raster pattern embodiments shown in
FIGS. 11 and12. In these embodiments, contour tool path 1040 may
step over into the raster pattern to fill at least a portion of
interior region 1050.
[0076] FIG. 16 is an alternative sectional view of section 15 shown
in FIG. 14, illustrating layer 1136, which is an alternative to
layer 1036 (shown in FIGS. 14 and 15) having a different stop
point, and where the references labels are increased by 100. As
shown in FIG. 16, contour tool path 1140 of layer 1136 includes
start point 1152 and stop point 1154, where start point 1152 is
located at the same position as start point 1052 (shown in FIG.
15). Stop point 1154, however, stops the deposition of the modeling
material prior to forming a complete ring for perimeter path 1138b.
While shown at the particular location in FIG. 16, stop point 1054
may be located at any distance from point 1194. This embodiment is
also suitable for extending seam 1164 inward within interior region
1150, thereby effectively eliminating the formation of bulges of
modeling material at seam 1164. Additionally, the step-over
arrangement also reduces the porosity of 3D model 26 at seam 1164
and the shortened length of perimeter path 1138b is beneficial for
use in thin-wall regions.
EXAMPLES
[0077] The present disclosure is more particularly described in the
following examples that are intended as illustrations only, since
numerous modifications and variations within the scope of the
present disclosure will be apparent to those skilled in the art.
Build operations were preformed with the method of the present
disclosure to fabricate 3D models of Examples 1-4, each having
concealed seams. Each 3D model of Examples 1-4 were built from the
same digital representation having a filled cylindrical
geometry.
[0078] For each 3D model of Examples 1-4, the digital
representation was provided to a computer capable of communicating
with an extrusion-based digital manufacturing system. The computer
then sliced the digital representation into multiple layers with a
software program commercially available under the trade designation
"INSIGHT" from Stratasys, Inc., Eden Prairie, Minn. The software
program also generated contour tool paths for each sliced layer. In
addition, the start and stop points of each contour tool path were
adjusted to predefined locations within the interior regions
defined by the respective contour tool paths.
[0079] The start and stop points for Example 1 were adjusted to an
open-square arrangement as depicted in layer 36 (shown in FIG. 3).
The start and stop points for Example 2 were adjusted to an
overlapped closed-square arrangement as depicted in layer 236
(shown in FIG. 6). The start and stop points for Example 3 were
adjusted to an converging-point arrangement as depicted in layer
536 (shown in FIG. 9). The start and stop points for Example 4 were
adjusted to an overlapped-cross arrangement as depicted in layer
536 (shown in FIG. 10). For each modified contour tool path, raster
tool paths were then generated within the interior regions, where
the raster tool paths accommodated the adjustments to the start and
stop locations of the contour tool paths.
[0080] In addition to the 3D models of Examples 1-4, a 3D model of
Comparative Example A was prepare from the same digital
representation and using the same above-discussed steps. However,
for Comparative Example A, the start and stop locations of the
contour tool paths were not adjusted. As such, the start and stop
locations remained collinear with the outer rings of the contour
tool paths.
[0081] For each 3D model of Examples 1-4 and Comparative Example A,
the resulting data was then transmitted to the extrusion-based
digital manufacturing system, which was a fused deposition modeling
system commercially available under the trade designation "FORTUS
400mc" from Stratasys, Inc., Eden Prairie, Minn. Based on the
received data, the system then built each 3D model from an
acrylonitrile-butadiene-styrene (ABS) copolymer modeling
material.
[0082] After the build operations were completed, the perimeter
path seams of each 3D model was visually inspected. For the 3D
model of Comparative Example A, the perimeter path seams exhibited
surface bulges of modeling material that were readily identifiable
by the naked eye. In comparison, however, the perimeter path seams
of the 3D models of each of Examples 1-4 did not exhibit any
surface bulging and were consistent between the successive layers.
As such, the method of the present disclosure is suitable for
effectively concealing the seams of the perimeter paths (created by
the contour tool paths). As discussed above, this may increase the
aesthetic and functional qualities of the resulting 3D models.
[0083] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *