The present invention relates to additive manufacturing of three-dimensional object in general, and, more particularly, to techniques for fabricating objects with non-orthogonal surfaces and internal structures.
Additive manufacturing is a technique for building a three-dimensional object from a mathematical model of the object. In the additive manufacturing technique called fused-deposition modeling, the object is built by feeding a thermoplastic filament into a heated extrusion head. The extrusion head heats and deposits the molten thermoplastic material as one or more runs of material. Typically, a run of material is shaped like a thread or a very thin run of toothpaste. When a run is deposited, it is just slightly above its melting point. After it is deposited, the run quickly solidifies and fuses with the runs that it touches.
Perhaps the greatest advantage of additive manufacturing is that it can build an object of any shape. To accomplish this, however, there are constraints on the sequence in which the runs can be deposited. First, each run must be supported. In other words, a run cannot be deposited on air. Therefore, each run must be deposited on:
There is a general methodology that is used in additive manufacturing that satisfies these constraints and enables the building of an object of any shape. The three-dimensional model of the object is modeled as hundreds or thousands of uniformly-thick horizontal layers. Each layer is modeled as hundreds or thousands of runs and voids. The object is then built, one run at a time, one layer at a time, only in the +Z direction.
There are, however, costs and disadvantages associated with traditional additive manufacturing.
Some embodiments of the present invention are able to manufacture three-dimensional objects without some of the costs and disadvantages for doing so in the prior art. For example, some embodiments of the present invention are able to manufacture an object by depositing a run of material to form layers that are non-planar and monotonic or non-planar and non-monotonic. This is, for example, advantageous for manufacturing objects with smooth non-planar surfaces (e.g., airplane wings, ducts, propellers, axles, etc.), objects whose external “grain” is visible and should be oriented in a particular manner, and objects that require non-planar internal structures to achieve desired mechanical properties.
The illustrative embodiment manufactures an object by depositing a run of material to form N deposition layers DL[1], . . . , DL[n], . . . , DL[N], where N is a positive integer and n is a positive integer in the range n ∈ {1, . . . , N}. Deposition layer DL[1] is deposited first, if necessary. Deposition layer DL[n+1] is deposited after and on deposition layer DL[n], and deposition layer DL[N] is deposited last, if necessary. The aggregate of deposition layers DL[1], . . . , DL[n], . . . , DL[N] constitute the object.
The parameters of deposition layers DL[1], . . . , DL[n], . . . , DL[N] equal the volume intersection of the object and archetype layers AL[1], . . . , AL[n], . . . , AL[N], respectively. Archetype layer AL[n] is a continuous function z=f(n,x,y) that is defined over the domain of the object, where x and y are real numbers in the X-Y plane. Archetype layer AL[n] resides at nominal elevation e(n) relative to the object, and archetype layer AL[n] has thickness t(n,x,y). Therefore, deposition layer DL[n] also resides at nominal elevation e(n) relative to the object and has thickness t(n,x,y) insofar as it intersects the object at coordinate <x,y,e(n)>.
Archetype layers AL[1], . . . , AL[n], . . . , AL[N] can have the same function (i.e., f(1,x,y)=f(n,x,y)=f(n+1,x,y)=f(N,x,y) for all n) or different functions (i.e., f(1,x,y)≠f(n,x,y)≠f(n+1,x,y)≠f(N,x,y)). This is advantageous, for example, when fabricating an object whose top and bottom surfaces are described by different non-planar surfaces (e.g., an airplane wing, etc.). In those cases, the archetype layer corresponding to the bottom surface might conform to the shape of the bottom surface and the archetype layer for the top surface might conform to the top surface. The intermediate archetype layers can either be planar or a family of surfaces that smoothly morph from the bottom surface to the top surface and have varying thicknesses or domains.
In accordance with the illustrative embodiment, at least one of archetype layers AL[1], . . . , AL[n], . . . , AL[N] is non-planar, and one or more of archetype layers AL[1], . . . , AL[n], . . . , AL[N] can be non-monotonic.
For the purposes of this specification, the following terms and their inflected forms are defined as follows:
CAD/CAM system 101 comprises the hardware and software necessary to direct build chamber 102, control robotic arm 121, deposition head 122, deposition nozzle 123, and turntable 110 to manufacture object 151. It will be clear to those skilled in the art, after reading this disclosure, how to make and use CAM controller 101.
Build chamber 102 is a thermally-insulated, temperature-controlled environment in which object 151 is manufactured. It will be clear to those skilled in art how to make and use build chamber 102.
Turntable 110 comprises a stepper motor under the control of CAM controller 101 that is capable of rotating platform 111 (and, consequently object 151) around the Z-axis. In particular, turntable 110 is capable of:
Platform 111 comprises hardware on which object 151 is manufactured. It will be clear to those skilled in the art how to make and use platform 111.
Robotic arm 121 is a seven-axis arm capable of depositing a run of material from any three-dimensional coordinate in the build chamber 102 to any other three-dimensional coordinate in build chamber 102 with deposition nozzle 123 at any approach angle. It will be clear to those skilled in the art how to make and use robotic arm 121.
Deposition head 122 is hardware that heats and deposits filament 131 (which may partially or wholly contain one or more fiber strands) via deposition nozzle 123.
Thermoplastic filament 131 comprises a continuous tow of carbon fiber that is impregnated with a thermoplastic, but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which thermoplastic filament 131 has a different fiber composition as described in U.S. patent application Ser. No. 14/184,010, which is incorporated by reference.
Thermoplastic filament 131 is deposited as a “run of material,” which is not shown in
At task 201, the spatial parameters of object 151 are specified in CAD/CAM system 101. In accordance with the illustrative embodiment, object 151 is described as a triangle mesh in well-known fashion. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which the object is described using a different convention (e.g., voxels, etc.).
As described in detail below and in the accompanying figures, object 151 is manufactured by depositing one or more runs of fiber-reinforced composite material in non-planar layers to form object 151. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that use a different material.
The deposition layers are designated DL[1], . . . , DL[n], . . . , DL[N], where N is a positive integer and n is a positive integer in the range n ∈ {1, . . . , N}. Deposition layer DL[1] is deposited first (if necessary). Deposition layer DL[n+1] is deposited on deposition layer DL[n], and deposition layer DL[N] is deposited last (if necessary).
Object 151 comprises one material—the carbon fiber-reinforced thermoplastic—but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that comprises two or more materials.
Object 151 does not comprise any cavities (i.e., wholly interior volumes that do not comprise material), but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative objects of the present invention that do comprise one or more cavities.
The surfaces of object 151 are either flat or convex, but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that are concave.
Object 151 comprises four vertices: OV[0], OV[1], OV[2], and OV[3], whose coordinates are listed in Table 1.
The coordinates of are specified:
Although the coordinates of object 151 are specified in millimeters, it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that are specified in any (lowercase ‘m’) metric system and any scale.
Although the coordinates of object 151 are specified in a right-hand Cartesian coordinate system, it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that are specified in a different coordinate system.
Although the coordinates of object 151 are specified such that the bottom of object 151 is at the X-Y plane, it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which the bottom of object 151 is not at the X-Y plane.
The triangle mesh of object 151 comprises four triangles OT[0], OT[1], OT[2], and OT[3]. Each triangle is described by an ordered-set of three vertices in right-hand-rule order so that the cross-product vector of the triangle faces into an absence of material (i.e., out of the tetrahedron). (If an object comprises a cavity, the triangles that describe the cavity are described by three vertices in right-hand-rule order so that the cross-product vector of the triangle faces into the cavity.) The four triangles are defined by the ordered set of vertices listed in Table 2.
In accordance with the illustrative embodiment, the description of object 151 is “watertight”—meaning that the description of object 151 includes a surface between every volume that contains material and every volume that does not contain material.
At task 202, CAD/CAM system 101 determines the value of N, which is maximum number of layers that might be needed in order to manufacture object 151.
The thickness of deposition layer DL[n] is given by the layer thickness function t(n,x,y), where x and y are coordinates in the X-Y plane. The layer thickness function t(n,x,y) enables the thickness of each layer to be specified (e.g., all layers can have the same thickness, some layers have different thicknesses, each layer has a different thickness, etc.). Furthermore, the layer thickness function t(n,x,y) enables the thickness of each layer to be specified at each x-y coordinate.
The value of N equals the smallest value of N that satisfies the relation:
Σn=1N tmin(n,x,y)≥H0 (Rel. 1)
where tmin(n,x,y) is the minimum thickness of layer n at coordinates x,y, H0 is the maximum width of object 151 in any dimension. The maximum width H0 of object 151 exists at each edge and equals 22.36 millimeters. In accordance with the illustrative embodiment, the value of t(n,x,y)=0.1 millimeters for all n, x, and y. Therefore, the smallest value of N that satisfies Relation 1 is 224.
At task 203, archetype layers AL[1], . . . , AL[n], AL[N] are specified. In accordance with the illustrative embodiment, archetype layer AL[n] is a continuous function z=f(n,x,y) that is defined over at least the full domain of object 151 (i.e., the footprint of the archetype layer fully covers the footprint of the three-dimensional object).
In accordance with the illustrative embodiment, all of archetype layers AL[1], . . . , AL[n], . . . , AL[N] are non-planar. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which one or more of the archetype layers are planar and one or more of the archetype layers are non-planar.
In accordance with the illustrative embodiment, all of archetype layers AL[1], . . . , AL[n], . . . , AL[N] are non-monotonic. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which one or more of the archetype layers are monotonic.
In accordance with the illustrative embodiment, archetype layers AL[1], AL[n], . . . , AL[N] are described as a triangular mesh that satisfies the following five properties:
In accordance with the illustrative embodiment of the present invention, all N archetype layers AL[1], . . . , AL[n], . . . , AL[N] are the same function (i.e., f(n,x,y)=f(n+1,x,y) for all n). It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which one or more archetype layers are a different function than one or more other archetype layers (e.g., f(1,x,y)≠f(n,x,y)≠f(n+1,x,y)≠f(n,x,y)).
In accordance with the illustrative embodiment, the thickness of archetype layer AL[n] is specified by the continuous function Δz=t(n,x,y). To simplify the discussion of the illustrative embodiment and the figures, the function t(n,x,y)=0.1 millimeters for all n, x, and y. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which t(n,x,y) is any function.
In accordance with the illustrative embodiment of the present invention, archetype layer AL[n] has a nominal elevation e(n) of:
z=e(n)=f(n, 0,0) (Eq. 1)
Therefore, archetype layer AL[1] has the lowest nominal elevation z=e(1)=f(1,0,0)=0.1 millimeters; archetype layer AL[n+1] has a higher nominal elevation than archetype layer AL[n] (i.e., e(n+1)>e(n), and archetype layer AL[N] has the highest nominal elevation z=e(N)=f(N,0,0)=22.4 millimeters.
Although archetype layer AL[100] equals the upper surface of object 151, it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which archetype layer AL[n] has any contour. Furthermore, it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which the contour of archetype layer AL[n] is unrelated to the shape of the object.
Archetype layer AL[n] comprises vertices: ASV[n,1], . . . , ASV[n,v], . . . , ASV[n,V], where:
Archetype layer AL[n] comprises three triangles AST[n,0], AST[n,1], and AST[n,2]. The three triangles are defined by the ordered set of vertices listed in Table 4.
It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that use any archetype layer that satisfies Properties I, II, III, IV, and V regardless of whether the archetype layer bears any similarity to the object to be manufactured.
For the following reasons, archetype layer 400 satisfies the above six properties:
Property I—archetype layer AL[n] is specified in millimeters.
Property II—archetype layer AL[n] is specified in a right-hand Cartesian coordinate system.
Property III—archetype layer AL[n] satisfies Property IV because the archetype layer is continuous and defined for the entire domain of object 151 (from Vertex OV[1] to Vertex OV[2] to Vertex OV[3]).
Property IV—archetype layer AL[n] satisfies Property V because the Z-axis component of the normal vector for each of triangles AST[0], AST[1], and AST[2] is positive, as can be seen in Table 3.
Property V—the angle between the normal vectors for each pair of adjacent triangles in archetype layer AL[n] is shown in Table 5.
In accordance with the illustrative embodiment, the coordinates for archetype layer AL[1] are listed in Table 6 (and depicted in
As another example, the coordinates for archetype layer AL[50] are listed in Table 7 (and depicted in
As another example, the coordinates for archetype layer AL[200] are listed in Table 8 (and depicted in
At task 204, CAD/CAM system 101 determines the domain of deposition layers DL[1], . . . , DL[n], . . . , DL[N]. In particular, deposition layer DL[n] equals the volume intersection of archetype layer AL[n] and object 151. It will be clear to those skilled in the art how to determine the volume intersection of archetype layer AL[n] and object 151.
The domain of deposition layer DL[1] is described by three triangles: DLT[1,0]. DLT[1,1], and DLT[1,2] and four vertices DLV[1,0], DLV[1,1], DLV[1,2], and DLV[1,3]. The coordinates associated with each triangle are listed in Table 8 and depicted in
The values of the coordinates in the triangles in deposition layer DL[1] are listed in Table 9.
The domain of deposition layer DL[2] is described by three triangles: DLT[2,0]. DLT[2,1], and DLT[2,2] and four vertices DLV[2,0], DLV[2,1], DLV[2,2], and DLV[2,3]. The coordinates associated with each triangle are listed in Table 10 and depicted in
The values of the coordinates in the triangles in deposition layer DL[2] are listed in Table 11.
The domain of deposition layer DL[99] is described by three triangles: DLT[99,0]. DLT[99,1], and DLT[99,2] and four vertices DLV[99,0], DLV[99,1], DLV[99,2], and DLV[99,3]. The coordinates associated with each triangle are listed in Table 12 and depicted in
The values of the coordinates in the triangles in deposition layer DL[99] are listed in Table 13.
The domain of deposition layer DL[100] is described by three triangles: DLT[100,0]. DLT[100,1], and DLT[100,2] and four vertices DLV[100,0], DLV[100,1], DLV[100,2], and DLV[100,3]. The coordinates associated with each triangle are listed in Table 14 and depicted in
The values of the coordinates in the triangles in deposition layer DL[100] are listed in Table 15.
The domains of deposition layers DL[101] through DL[224] are empty because the volume intersection of archetype layers AL[ 101] through AL[224] and object 151 is empty.
At task 205, additive manufacturing system 100 deposits one continuous run of material to form layers DL[1], . . . , DL[n], . . . , DL[N]. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which two or more runs of material are used to manufacture object 151. For example, in some embodiments of the present invention, one run of material is deposited to form deposition layer DL[n] and a second run of material is deposited to form deposition layer DL[n+1].
It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.
The following patent applications are incorporated by reference for their description of how to make and use additive manufacturing system 100: U.S. patent application Ser. No. 15/375,832, filing date Dec. 12, 2016;U.S. patent application Ser. No. 15/232,767, filing date Aug. 9, 2016;U.S. patent application Ser. No. 14/574,237, filing date Dec. 17, 2014; andU.S. patent application Ser. No. 14/623,471, filing date Feb. 16, 2015.