Tool Path Data Generation in Additive Manufacturing

Abstract

Generating tool path data for an additive manufacturing apparatus comprises providing object design data in which at least a part of a physical object is represented by a line. A section of the line is then sliced using an intermediate slicing layer that is provided between first and second physical build layers of the additive manufacturing apparatus. The slicing generates an intermediate layer point at the intersection of the section of the line and the intermediate slicing layer, with the intermediate layer point being located between the first and second physical build layers. The intermediate layer point is then projected to a projected build layer point that lies within a physical build layer of the additive manufacturing apparatus. The projected build layer point is used to provide tool path data for that physical build layer. A similar process can be used in which the physical object is represented by a surface.

Claims

1. A computer implemented method of generating tool path data to be followed by an additive manufacturing apparatus when manufacturing a physical object, the method comprising: providing object design data in which at least a part of the physical object is represented by a line or surface; slicing a section of the line or surface using an intermediate slicing layer that is provided between first and second physical build layers of the additive manufacturing apparatus, wherein slicing the section of the line or surface generates an intermediate layer point or line at an intersection of the section of the line or surface and the intermediate slicing layer, wherein the intermediate layer point or line is located between the first and second physical build layers; projecting the intermediate layer point or line to a projected build layer point or line that lies within a physical build layer of the additive manufacturing apparatus; and using the projected build layer point or line to provide tool path data for that physical build layer.

2. A method as claimed in claim 1, wherein slicing the section of the line or surface comprises slicing the section of the line or surface using plural intermediate slicing layers that are provided between the first and second physical build layers, wherein slicing the section of the line or surface comprises generating respective intermediate layer points or lines at intersections of the section of the line or surface and respective intermediate slicing layers, and wherein the intermediate layer points or lines are located between the first and second physical build layers, the method further comprising projecting each intermediate layer point or line to a respective projected build layer point or line that lies within a physical build layer of the additive manufacturing apparatus, and using the projected build layer point or line to provide tool path data for that physical build layer.

3. A method as claimed in claim 1, wherein a number of intermediate slicing layers used when slicing the section of the line or surface is selected based on at least one of: (i) a build angle for that section of the line or surface; (ii) a build layer spacing between the first and second physical build layers of the additive manufacturing apparatus; and (iii) a desired tool path spacing for the additive manufacturing apparatus.

4. A method as claimed in claim 3, wherein the build angle for the section of the line or surface is an angle between a normal to that section of the line or surface and a normal to a physical build layer of the additive manufacturing apparatus.

5. A method as claimed in claim 3, wherein at least one of: (i) a relatively greater number of intermediate slicing layers is used for a section of the line or surface that is closer to being parallel to a physical build layer of the additive manufacturing apparatus, and a relatively smaller number of intermediate slicing layers is used for a section of the line or surface that is closer to being perpendicular to a physical build layer of the additive manufacturing apparatus; (ii) a relatively greater number of intermediate slicing layers is used for a relatively greater build layer spacing, and a relatively smaller number of intermediate slicing layers is used for a relatively smaller build layer spacing; and (iii) a relatively greater number of intermediate slicing layers is used for a relatively smaller desired tool path spacing, and a relatively smaller number of intermediate slicing layers is used for a relatively larger desired tool path spacing.

6-9. (canceled)

10. A method as claimed in claim 1, wherein slicing the section of the line or surface further comprises slicing the section of the line or surface using one or more physical build layers of the additive manufacturing apparatus, wherein slicing the section of the line or surface using one or more physical build layers of the additive manufacturing apparatus comprises directly generating one or more direct build layer points or lines that lie within the one or more physical build layers of the additive manufacturing apparatus.

11. A method as claimed in claim 1, wherein a number of intermediate slicing layers used when slicing one or more other sections of the line or surface is zero.

12. A method as claimed in claim 1, wherein n intermediate slicing layers are used when slicing a section of the line or surface when the build angle θ for the section of the line or surface is in a range θ.sub.n≥θ>θ.sub.n+1, where θ.sub.n and θ.sub.n+1 are selected angles for a or each given n.

13. A method as claimed in claim 1, wherein n intermediate slicing layers are used when slicing the section of the line or surface when a build angle θ for the section of the line or surface is in a range arctan(S.sub.BL/k.sub.θnS.sub.TP)°>θ>arctan(S.sub.BL/k.sub.θn+1S.sub.TP)°, where k.sub.θn and k.sub.θn+1 are selected values for a or each given n, S.sub.BL is a build layer spacing between the first and second physical build layers of the additive manufacturing apparatus, and S.sub.TP is a desired tool path spacing.

14. A method as claimed in claim 1, wherein a spacing of the intermediate slicing layers used when slicing the section of the line or surface is substantially uniform.

15. A method as claimed in claim 1, wherein the line or surface comprises plural line or surface sections, the method further comprising including each line or surface section in one of plural groups of one or more line or surface sections based on a build angle for that line or surface section, and using a same number of intermediate slicing layers when slicing plural line or surface sections of a particular group.

16. A method as claimed in claim 1, wherein the intermediate layer point or line is projected to its closest physical build layer of the additive manufacturing apparatus.

17. A method as claimed in claim 1, wherein one or more build layer points or lines in a relatively upper build layer are also projected downwards to a relatively lower build layer.

18. A method as claimed in claim 1, wherein at least part of the physical object is represented at least one of: (i) abstractly by the line of surface; and (ii) parametrically by the line or surface.

19. A method as claimed in claim 1, wherein the line or surface does not form part of at least one of: (i) a volumetric representation of the physical object; (ii) a filled representation of the physical object; and (iii) a solid representation of the physical object.

20. A method as claimed in claim 1, wherein an elongate structural feature of the physical object is represented by the line.

21. A method as claimed in claim 1, wherein a wall structural feature of the physical object is represented by the surface.

22. A data processing system for generating tool path data for use in additive manufacturing, the system comprising processing circuitry configured to perform a method of generating tool path data to be followed by an additive manufacturing apparatus when manufacturing a physical object, the processing circuitry being configured to: provide object design data in which at least a part of the physical object is represented by a line or surface; slice a section of the line or surface using an intermediate slicing layer that is provided between first and second physical build layers of the additive manufacturing apparatus, wherein slicing the section of the line or surface generates an intermediate layer point or line at an intersection of the section of the line or surface and the intermediate slicing layer, wherein the intermediate layer point or line is located between the first and second physical build layers; project the intermediate layer point or line to a projected build layer point or line that lies within a physical build layer of the additive manufacturing apparatus; and use the projected build layer point or line to provide tool path data for that physical build layer.

23. A non transitory computer readable medium comprising computer software code which when used to operate a data processing system comprising one or more data processors causes, in conjunction with said one or more data processors, said system to carry out a method of generating tool path data to be followed by an additive manufacturing apparatus when manufacturing a physical object, the method comprising: providing object design data in which at least a part of the physical object is represented by a line or surface; slicing a section of the line or surface using an intermediate slicing layer that is provided between first and second physical build layers of the additive manufacturing apparatus, wherein slicing the section of the line or surface generates an intermediate layer point or line at an intersection of the section of the line or surface and the intermediate slicing layer, wherein the intermediate layer point or line is located between the first and second physical build layers; projecting the intermediate layer point or line to a projected build layer point or line that lies within a physical build layer of the additive manufacturing apparatus; and using the projected build layer point or line to provide tool path data for that physical build layer.

24-25. (canceled)

26. A method as claimed in claim 1, further comprising manufacturing the physical object, wherein manufacturing the physical object comprises using the additive manufacturing apparatus to implement tool path data.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Various embodiments will now be described by way of example only and with reference to the accompanying drawings, in which:

[0091] FIG. 1 shows a conventional method of generating and using tool path data;

[0092] FIG. 2 shows a method of generating and using tool path data according to embodiments;

[0093] FIG. 3 illustrates a method of generating tool path data from a line that at least partially represents an object according to an embodiment; and

[0094] FIGS. 4A and 4B illustrate a method of generating tool path data from a surface that at least partially represents an object according to an embodiment.

DETAILED DESCRIPTION

[0095] FIG. 1 shows a conventional method of generating tool path data for use in additive manufacturing and using the tool path data to manufacture a physical object.

[0096] The method 100 begins at step 102. In step 102, object design data is developed from a design concept using conventional CAD (computer aided design) software. The object design data may comprise a volumetric representation of the object that comprises the vertices of polygons that form the object. Then, in step 104, the object design data is modified and orientated for additive manufacture, and supports are added if necessary for the additive manufacture, using software such as conventional CAD software or Materialise Magics (RTM). Then, in step 106, tool path data is generated from closed contours derived from the object design data using generic software or specific software for an additive manufacturing apparatus. The tool path data can be derived using a raster pattern of tool path points. Then, in step 108, a database provides additive manufacturing parameters, such as laser power, specific to a material to be used in the additive manufacturing. Then, in step 110, the additive manufacturing apparatus interprets the tool path data and builds the object using the specified additive manufacturing parameters for the material being used.

[0097] FIG. 2 shows a method of generating tool path data for use in additive manufacturing and using the tool path data to manufacture a physical object according to embodiments.

[0098] The method 200 begins at step 202. In step 202, object design data is again developed from a design concept using conventional CAD software. The object design data may comprise a volumetric representation of the object that comprises the vertices of polygons that form the object. Then, in step 204, the object design data for any filled or solid geometry is modified and orientated for additive manufacture, and supports are added if necessary for the additive manufacture, using software such as conventional CAD software or Materialise Magics (RTM). Then, in step 206, tool path data is generated from closed contours derived from the object design data for any filled geometry using generic software or specific software for an additive manufacturing apparatus. The tool path data can be derived using a raster pattern of tool path points.

[0099] Also in this embodiment, in step 212, the object design data for any non-filled, hollow or “thin” geometry is automatically converted to object design data that comprises a parametric representation using suitable software, such as a plugin for the otherwise conventional CAD software. The parametric representation defines lines and/or surfaces for the non-filled, hollow or “thin” geometry that have specified thicknesses. Then, in step 214, tool path data is automatically generated from the converted object design data for the non-filled, hollow or “thin” geometry using suitable software. This step will be described in more detail below with reference to FIGS. 3, 4A and 4B. Also, in step 216, tool path data may be automatically generated from the closed contours of the object design data for any filled geometry. Then, in step 208, a database provides additive manufacturing parameters, such as laser power, based on the material and/or tool path spacing(s) to be used in the additive manufacturing. Then, in step 218, the various sets of tool path data are merged. Then, in step 210, the additive manufacturing apparatus interprets the merged tool path data and builds the object using the specified additive manufacturing parameters for the material and/or tool path spacing(s) being used.

[0100] FIG. 3 illustrates a method 300 of generating tool path data from a line that at least partially represents an object according to an embodiment.

[0101] In this embodiment, a structural feature of an object is represented in the object design data by a line 302. The line 302 is shown relative to plural physical build layers 304 for the additive manufacturing apparatus that will be used to manufacture the object. In this embodiment, the physical build layer spacing S.sub.BL is 60 μm and the desired tool path spacing S.sub.TP is 30 μm±5 μm. Other build layer spacings S.sub.BL and tool path spacings S.sub.TP can be used as desired.

[0102] In this embodiment, the line 302 comprises a closed hexagonal polyline comprising six straight line sections 306a, 306b, 308a, 308b, 310a, 310b, with each section being defined by a start vertex and an end vertex. However, in other embodiments, other line geometry such as open lines, lines having more or fewer line sections (including only a single line section) and/or one or more curved line sections may be used to represent an object as desired.

[0103] The method 300 begins in stage 1, in which the line sections 306a, 306b, 308a, 308b, 310a, 310b are grouped into “domains” based on a build angle θ for each line section. In this embodiment, the build angle θ for a line section is defined as the angle between a normal to the line section and a normal to the plane of a build layer that intersects that section. Thus, a line section that is closer to being perpendicular to the planes of the build layers 304 would have a higher or “steeper” build angle θ and a line section that is closer to being parallel to the planes of the build layers 304 would have a lower or “shallower” build angle θ. In this embodiment, the relatively more upright line sections 306a and 306b are grouped into a first domain, the relatively shallower line sections 308a and 308b are grouped into a second domain, and the relatively even shallower line sections 310a and 310b are grouped into a third domain.

[0104] Then, in stage 2, the line sections are sliced at the physical build layers to directly generate direct build layer points. The line sections of the respective domains are also sliced using different numbers of intermediate slicing layers depending on the build angles 8 for the line sections within the respective domains.

[0105] In particular, in this embodiment, the relatively more upright line sections 306a and 306b of the first domain are sliced at the physical build layers to directly generate direct build layer points (such as direct build layer point 312). However, these relatively more upright line sections 306a and 306b are not sliced using any intermediate layers between each given pair of first and second physical build layers. This is because these relatively more upright line sections 306a and 306b can be suitably manufactured using only a single build layer point per physical build layer.

[0106] The relatively shallower line sections 308a and 308b of the second domain are also sliced at the physical build layers to directly generate direct build layer points (such as direct build layer point 314). Furthermore, these relatively shallower line sections 308a and 308b are also sliced using a single intermediate slicing layer between each given pair of adjacent first and second physical build layers to generate an intermediate layer point (such as intermediate layer point 316) between each given pair of adjacent first and second physical build layers. This is because these relatively shallower line sections 308a and 308b will benefit from being manufactured using more physical build layer points per physical build layer. Here, the intermediate slicing layer spacing is S.sub.IL=S.sub.BL/(n+1)=60 μm/(1+1)=30 μm.

[0107] Similarly, the relatively even shallower line sections 310a and 310b of the third domain are also sliced at the physical build layers to directly generate direct build layer points (such as direct build layer point 318). Furthermore, these relatively even shallower line sections 310a and 310b are also sliced using six intermediate slicing layers between each given pair of adjacent first and second physical build layers to give six intermediate layer points (such as intermediate layer points 320) between each given pair of adjacent first and second physical build layers. This is because those relatively even shallower line sections 310a and 310b will benefit from being manufactured using relatively even more build layer points. Here, the intermediate slicing layer spacing is S.sub.IL=S.sub.BL/(n+1)=60 μm/(6+1)=8.57 μm.

[0108] Then, in stage 3, the intermediate layer points are projected upwards or downwards to the closest physical build layer. For example, intermediate layer point 316 is projected upwards to projected build layer point 322. Similarly, three of the six intermediate layer points 320 are projected upwards to projected build layer points 324. However, the remaining three of the intermediate layer points 320 are projected downwards to projected build layer points 326. This process of projecting the intermediate layer points to the closest physical build layer allows the resultant physical object to more closely resemble the desired line geometry.

[0109] Then, in optional stage 4, the build layer points for any line sections for which intermediate layer points have been generated are also downwardly projected to a lower build layer. For example, directly generated build layer point 314 and projected build layer point 322 for the line section 308a are projected downwards to generate further build layer points 328 and 330 respectively. This optional process allows the resultant physical object to have improved structural integrity.

[0110] Plural build layer points within a physical build layer may then be connected together to form a tool path for that physical build layer.

[0111] The method 300 of FIG. 3 accordingly provides a way to generate highly representative tool path data by making use of one or more intermediate slicing layers provided between the relatively coarser physical build layers. The resultant tool path data can accordingly make better use of the resolution of the particular additive manufacturing apparatus to be used to make the object. The tool path data can also produce objects having finer detail and/or superior material and/or structural properties, when compared with existing additive manufacturing arrangements. The method 300 of FIG. 3 also provides a way to generate tool path data from lines that represent an object (e.g. in an abstract and/or parametric manner), for example without generating closed contours directly from a volumetric (e.g. STL) representation of the object. This means that the process of generating the tool path data can be less computationally intensive when compared with existing arrangements.

[0112] Although the method 300 of FIG. 3 shows two dimensional lines that provide one dimensional tool path data for a physical build layer, it will be appreciated that the lines would generally be defined and processed in three dimensions and thus the tool path data would generally be defined in the two dimensions for a physical build layer.

[0113] FIGS. 4A and 4B illustrate a method 400 of generating tool path data from a surface that at least partially represents an object according to an embodiment. FIG. 4A shows a perspective view and FIG. 4B shows a corresponding cross-sectional view.

[0114] In this embodiment, a structural feature of an object is represented in the object design data by a surface 402. Again, the surface 402 is shown relative to plural physical build layers 404 for the additive manufacturing apparatus that will be used to manufacture the object. Again, in this embodiment, the physical build layer spacing S.sub.BL is 60 μm and the desired tool path spacing S.sub.TP is 30 μm±5 μm. Again, other build layer spacings S.sub.BL and tool path spacings S.sub.TP can be used as desired.

[0115] In this embodiment, the surface 402 comprises an open mesh comprising 90 polygonal (triangular) surface sections or “faces”, with each surface section or “face” being defined by three vertices. However, in other embodiments, other surface geometry such as closed surfaces, surfaces having more or fewer surface sections (including only a single surface section) and/or one or more curved surface sections may be used to represent an object as desired.

[0116] The method 400 begins in stage 1, in which the surface sections are grouped into domains based on a build angle θ for each surface section. In this embodiment, the build angle θ for a surface section is defined as the angle between a normal to the surface section and a normal to the plane of a build layer that intersects that section. Thus, a surface section or “face” that is closer to being perpendicular to the planes of the build layers 404 would have a higher or “steeper” build angle θ and a surface section or “face” that is closer to being parallel to the planes of the build layers 404 would have a lower or “shallower” build angle θ. In this embodiment, an area of 60 relatively more upright surface sections are grouped into a first domain 406, a strip of 10 relatively shallower surface sections are grouped into a second domain 408, another strip of 10 relatively even shallower surface sections are grouped into a third domain 410, and yet another strip of 10 relatively even shallower surface sections are grouped into a fourth domain 412.

[0117] Then, in stage 2, the surface sections are sliced at the physical build layers to directly generate physical build layer lines. The surface sections of the respective domains are also sliced using different numbers of intermediate slicing layers depending on the build angles 8 for the surface sections within the respective domains.

[0118] In particular, in this embodiment, the relatively more upright surface sections of the first domain 406 are sliced at the physical build layers to directly generate physical build layer lines (such as physical build layer line 414). However, these relatively more upright surface sections are not sliced using any intermediate layers between each given pair of first and second physical build layers. This is because these relatively more upright surface sections can be suitably manufactured using only a single build layer line per physical build layer.

[0119] The relatively shallower surface sections of the second, third and fourth domains are also sliced at the physical build layers to directly generate direct build layer lines (such as direct build layer line 416). Furthermore, these relatively shallower surface sections are also sliced using one or more intermediate slicing layers between each given pair of first and second physical build layers to generate intermediate layer lines (such as intermediate layer lines 418 and 420) between each given pair of first and second physical build layers. In particular, the relatively shallower surface sections of the second domain 408 are sliced using two intermediate slicing layers between non-adjacent physical build layers, the relatively even shallower surface sections of the third domain 410 are sliced using one intermediate slicing layer between adjacent physical build layers, and the relatively even shallower surface sections of the fourth domain 412 are sliced using two intermediate slicing layers between adjacent physical build layers. This is because these progressively relatively shallower surface sections would benefit from being manufactured using progressively more physical build layer lines per physical build layer.

[0120] Then, in stage 3, the intermediate layer lines are projected upwards or downwards to the closest physical build layer. For example, intermediate layer line 418 is projected upwards to projected build layer line 422 and intermediate layer line 420 is projected downwards to projected build layer line 424. This process of projecting the intermediate layer lines to the closest physical build layer allows the resultant physical object to more closely resemble the desired surface geometry.

[0121] Then, in optional stage 4, the build layer lines for any surface sections for which intermediate layer lines have been generated are also downwardly projected to a lower build layer. For example, directly generated layer line 416 and projected layer line 422 are projected downwards to generate further build layer lines 426 and 428 respectively. This optional process allows the resultant physical object to have improved structural integrity.

[0122] A build layer line within a physical build layer may be used as a tool path for that physical build layer. Alternatively, plural build layer lines within a physical build layer may be connected together to form a tool path for that physical build layer.

[0123] The method 400 of FIGS. 4A and 4B accordingly again provides a way to generate highly representative tool path data by making use of one or more intermediate slicing layers provided between relatively coarser resolution physical build layers. The resultant tool path data can accordingly make better use of the resolution of the particular additive manufacturing apparatus to be used to make the object. The tool path data can also produce objects having finer detail and/or superior material and/or structural properties, when compared with existing additive manufacturing arrangements. The method 400 of FIGS. 4A and 4B also provides a way to generate tool path data from surfaces that represent an object (e.g. in an abstract and/or parametric manner), for example without generating closed contours directly from a volumetric (e.g. STL) representation of the object. This means that the process of generating the tool path data can be less computationally intensive when compared with existing arrangements.

[0124] Although the present invention has been described with reference to various embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the accompanying claims.