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WO2021230858A1 - Identification de surfaces intérieures - Google Patents

Identification de surfaces intérieures Download PDF

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Publication number
WO2021230858A1
WO2021230858A1 PCT/US2020/032461 US2020032461W WO2021230858A1 WO 2021230858 A1 WO2021230858 A1 WO 2021230858A1 US 2020032461 W US2020032461 W US 2020032461W WO 2021230858 A1 WO2021230858 A1 WO 2021230858A1
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WO
WIPO (PCT)
Prior art keywords
distance
determining
point
boundary
processing circuitry
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2020/032461
Other languages
English (en)
Inventor
Sergio GONZALEZ MARTIN
Alex CARRUESCO LLORENS
Manuel Freire Garcia
David RAMIREZ MUELA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hewlett Packard Development Co LP
Original Assignee
Hewlett Packard Development Co LP
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hewlett Packard Development Co LP filed Critical Hewlett Packard Development Co LP
Priority to PCT/US2020/032461 priority Critical patent/WO2021230858A1/fr
Publication of WO2021230858A1 publication Critical patent/WO2021230858A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/30—Auxiliary operations or equipment
    • B29C64/386—Data acquisition or data processing for additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/10—Formation of a green body
    • B22F10/14—Formation of a green body by jetting of binder onto a bed of metal powder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/80—Data acquisition or data processing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y50/00—Data acquisition or data processing for additive manufacturing
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/10—Additive manufacturing, e.g. 3D printing
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/17—Mechanical parametric or variational design
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • Additive manufacturing techniques may generate a three-dimensional object through the solidification of a build material, for example on a layer-by-layer basis.
  • build material may be supplied in a layer-wise manner and the solidification method may include heating the layers of build material to cause melting in selected regions.
  • chemical solidification methods may be used.
  • Figure 1 is a flowchart of an example of a method of determining whether a point is on an interior surface of an object model
  • Figure 2 is a flowchart of another example of a method of determining whether a point is on an interior surface of an object model
  • Figures 3A to 3D are example representations of a portion of a plane of a fabrication chamber
  • Figure 4 is a flowchart of an example of a method of determining a geometrical compensation to be applied to a model of a build volume
  • Figure 5 is a simplified schematic drawing of an example apparatus
  • Figure 6 is a simplified schematic drawing of an example apparatus for additive manufacturing.
  • Figure 7 and Figure 8 are simplified schematic drawings of an example machine readable medium associated with a processor.
  • Additive manufacturing techniques may generate a three-dimensional object through the solidification of a build material.
  • the build material is a powder-like granular material, which may for example be a plastic, ceramic or metal powder and the properties of generated objects may depend on the type of build material and the type of solidification mechanism used.
  • the powder may be formed from, or may include, short fibres that may, for example, have been cut into short lengths from long strands or threads of material.
  • Build material may be deposited, for example on a print bed and processed layer by layer, for example within a fabrication chamber.
  • a suitable build material may be PA12 build material commercially referred to as V1 R10A “HP PA12” available from HP Inc.
  • selective solidification is achieved through directional application of energy, for example using a laser or electron beam which results in solidification of build material where the directional energy is applied.
  • at least one print agent may be selectively applied to the build material and may be liquid when applied.
  • a fusing agent also termed a ‘coalescence agent’ or ‘coalescing agent’
  • the fusing agent may have a composition which absorbs energy such that, when energy (for example, heat) is applied to the layer, the build material to which it has been applied heats up, coalesces and solidifies, upon cooling, to form a slice of the three-dimensional object in accordance with the pattern.
  • energy for example, heat
  • coalescence may be achieved in some other manner.
  • a suitable fusing agent may be an ink-type formulation comprising carbon black, such as, for example, the fusing agent formulation commercially referred to as V1Q60A “HP fusing agent” available from HP Inc.
  • a fusing agent may comprise any or any combination of an infra-red light absorber, a near infra-red light absorber, a visible light absorber and a UV light absorber.
  • fusing agents comprising visible light absorption enhancers are dye based colored ink and pigment based colored ink, such as inks commercially referred to as CE039A and CE042A available from HP Inc.
  • a print agent may comprise a coalescence modifier agent, which acts to modify the effects of a fusing agent for example by reducing or increasing coalescence or to assist in producing a particular finish or appearance of an object, and such agents may therefore be termed detailing agents.
  • detailing agent may be used near and outside edge surfaces of an object being printed to reduce coalescence.
  • a suitable detailing agent may be a formulation commercially referred to as V1Q61A “HP detailing agent” available from HP Inc.
  • a coloring agent for example comprising a dye or colorant, may in some examples be used as a fusing agent or a coalescence modifier agent, and/or as a print agent to provide a particular color for the object.
  • additive manufacturing systems may generate objects based on structural design data. This may involve a designer designing a three-dimensional model of an object to be generated, for example using a computer aided design (CAD) application.
  • the model may define the solid portions of the object.
  • the model data may comprise, or can be processed to derive, slices or parallel planes of the model. Each slice may define a portion of a respective layer of build material that is to be solidified or caused to coalesce by the additive manufacturing system.
  • deformations may occur resulting in an object being generated which does not have the expected dimensions.
  • the particular deformations may depend on any or any combination of factors such as the build material used, the type of additive manufacturing, the location of the object within the fabrication chamber of the additive manufacturing apparatus, object volume and the like.
  • fusing agent may be associated with a region of the layer which is intended to fuse.
  • build material of neighbouring regions may become heated and fuse to the outside of the object (in some examples, being fully or partially melted, or adhering to melted build material as powder). Therefore, a dimension of an object may be larger than the region(s) to which fusing agent is applied.
  • the object volume as described in object model data may be reduced.
  • objects may be smaller following object generation than is specified in object model data. For example, some build materials used to generate objects may shrink on cooling. Therefore, an object volume in object model data may be increased to compensate for the anticipated reduction in volume.
  • the particular deformations may depend on the object’s location within the fabrication chamber of the additive manufacturing apparatus. This may be because the thermal characteristics vary throughout the fabrication chamber, for example there may be small differences in temperature in different locations. In some examples, objects which are near the bottom of the chamber may be maintained at a higher temperature for a longer period than those located near the top of the fabrication chamber because objects generated near the bottom of the chamber will be generated near the start of the fabrication process, whereas those near the top will be generated later in the process. This may lead to a difference in cooling rates, which may impact deformations.
  • a particular object may be subject to mechanisms which result in growth and/or shrinkage, and the appropriate transformation to apply may be influenced by the different degrees to which an object may be affected by such processes.
  • Such compensations may be applied using geometrical transformation(s) which may include scaling and/or offsets.
  • a geometrical transformation may comprise at least one scaling factor and/or at least one offset value, and in some examples associate a scaling factor and/or offset value with at least one of three orthogonal axes (e.g. x, y and z, wherein the z-direction is taken herein to be the direction perpendicular to layers of deposited build material and x- and y-directions are in the plane of the deposited layers).
  • a scaling factor may be used to multiply object dimensions in the direction of at least one axis by a value, which may be greater than 1 in order to increase the dimension(s) and less than 1 to reduce the dimension(s), or equal to 1 to have no effect.
  • the scaling factor may be applied to dimensions of an object model, for example being applied to a mesh model of the object.
  • An offset may specify, for example by a specified distance or a number of defined voxels (i.e. 3D pixels), an amount to add or remove from a surface of the object (or a perimeter within a layer).
  • an offset distance in an axis may be specified and the object may be eroded or may be dilated (i.e., inflated or enlarged) by this distance, for example by moving the vertices of a mesh in the case that the object model is a mesh model, or adding/subtracting a number of voxels in a voxelised model although other methods of providing an offset may be used in other examples.
  • a geometrical compensation may be applied to the whole fabrication chamber.
  • the geometrical compensation may comprise a geometrical compensation for each of the x-, y- and z-directions.
  • the geometrical compensation comprises a scaling and an offset for each of the x-, y-, and z- directions, and so is defined by six values.
  • the deformations, and therefore the appropriate compensation may vary with location within the fabrication chamber. Therefore, there may be a plurality of geometrical compensation value sets, each relating to a different location, and/or a value set may be selected or derived based on the intended location of object generation.
  • a model describing the object to be generated, or a model describing the whole contents of a fabrication chamber may be modified before commencing the build process.
  • the modifications may comprise a scaling, whereby the object is ‘stretched’ or ‘compressed’ along an axis or axes and/or a surface offset operation which comprises applying either an erosion or dilation operation to a surface of the object.
  • Figure 1 is an example of a method, which may comprise a computer implemented method for determining whether a point is on an interior surface of an object model to be generated in a build volume.
  • the method comprises, in block 102, obtaining, by processing circuitry, a model of at least part of a fabrication chamber characterising a spatial arrangement of object models, the object models representing objects to be generated in a first additive manufacturing operation.
  • the arrangement of objects may be determined by any suitable method.
  • an arrangement of objects may be determined to reduce object generation time, to reduce the quantity of build material used, to reduce thermal interactions between objects, to increase the quantity of objects which may be generated, user specified or based on any other parameter.
  • the model may be a data model and may for example be obtained from a memory, or over a network, or the like.
  • the proximity of a surface of an object to another surface can affect the thermal behaviour of that portion of the object. For example, if a surface of an object is in close proximity to another surface, it may experience elevated temperatures for a longer time relative to other surfaces of the object. This can cause additional build material to adhere to the surface, increasing the dimensions of that surface relative to their intended dimensions and/or cooling times may be longer, which may affect shrinkage behaviour. In other words, regions with higher packing density can retain more heat. Interior surfaces of an object (i.e. object surfaces which face one another) may be in relatively close proximity. For example, when arranging the objects within the fabrication chamber, the arrangement can take account of their proximity to other objects and arrange them accordingly to reduce such defects.
  • interior surfaces may be fully or partially enclosed by solidified material in a manner which is less often the case for exterior surfaces. Therefore, it may be intended to apply different geometrical compensation to interior surfaces and/or to perform some other modification in determining how to generate the object, such as a modification of an application of print agent. For example, additional detailing agent may be applied next to interior surfaces compared to other surfaces. Flowever, in order to apply different geometrical compensations or other modifications, the relevant surfaces are to be identified.
  • the method comprises, in block 104 identifying, using processing circuitry (which may be the processing circuitry referred to in block 102), a first point on a first object surface of a first object model.
  • the method may determine for this point, and for other points, whether they are points on interior surfaces.
  • the method may be performed for a single point on a surface or may be performed iteratively for each of a plurality of different points to determine for each of the plurality of points whether they are on interior surfaces. For example, points may be selected on the basis that they are separated by a predetermined distance, or may be selected randomly, or in some other way. In some examples, a point may be selected based on other criteria, such as whether it is in a concave portion of a surface.
  • a concave portion of a surface may be identified by computing a convex hull of all points on the surface the points which do not lie on the convex hull are points which are in a concavity. Therefore, in some examples, identifying points comprises calculating the convex hull and selecting points which do not lie on the convex hull. The method may then be performed for each of the selected points.
  • the method comprises, in block 106 determining, using processing circuitry (which may be the processing circuitry referred to in block 102 and/or block 104) a first separation between the first point and an opposing object surface.
  • the opposing object surface may be defined as a surface which has a normal (exterior to the object) within a predetermined range of angles of the normal of the first surface.
  • opposing surfaces may be those having normal vectors having a relative angle which is at least 90 e , or in some examples having normal vectors which are substantially opposed (for example, generally pointed towards one another).
  • opposing surfaces may be those having normal vectors which have a relative angle which is within a predetermined range of 180 e , for example within 5 e , 10 e , 20 e , 30 e of 180 e or the like.
  • the first separation may also be the shortest uninterrupted (i.e. not intersecting any object models) straight line distance between the first point and an opposing object surface.
  • the opposing object surface may be a surface on the first object - in which case the surface may be an interior, or internal, surface- or another object, in which case the surface is not identified as an interior/internal surface.
  • the method comprises, in block 108 determining, using processing circuitry (which may be the processing circuitry referred to in block 102, 104 and/or block 106) a second separation between the first point and a boundary which is equidistant between the first object surface and a surface of a second object model representing a second object.
  • processing circuitry which may be the processing circuitry referred to in block 102, 104 and/or block 106
  • a boundary is determined which surrounds each object model, and each point on a boundary is equidistant between its nearest object models. Examples of how the boundary may be determined are described in more detail in relation to Figures 3A to 3D.
  • the method comprises, in block 110, comparing the first separation to the second separation.
  • the method comprises, in block 112, identifying interior surfaces by determining, using processing circuitry (which may be the processing circuitry referred to in block 102, 104, 106 and/or block 108), that the point is a point on an interior surface.
  • processing circuitry which may be the processing circuitry referred to in block 102, 104, 106 and/or block 108
  • the method comprises determining that the point is a point on an exterior surface.
  • this may also be seen when two interior surfaces are separated by a sufficient distance that they are not closer to each other than they are to the object boundary, for example in relatively wide cavities. The method will not identify such surfaces. However, as they are fairly well spaced, they may in any event be less subject to the conditions which result in different deformations in closely spaced interior surfaces.
  • the point in the surface is in relatively close proximity to another surface, and therefore is identified as a point on an interior surface. Identification of a point as being on an interior surface may be used when determining the geometrical compensation to be applied at that position.
  • the method further comprises, in block 114, determining, by processing circuitry, (which may be the processing circuitry referred to in block 102, 104, 106, 108 and/or block 1010) object generation instructions wherein the determination of object generation instructions differs for identified interior surfaces compared to other surfaces.
  • Determining object generation instructions may comprise, in some examples, modifying the object model data to include a geometrical compensation and/or determination of amounts of print agents to be used in generating the object and/or determination of the location of placement of such print agents.
  • the object generation instructions, or the process of determining the instructions may comprise a modification for interior surface(s).
  • the modification may be a modification to a geometrical compensation and/or any other modification to the determination of object generation instructions such as a modification of an amount of a print agent, for example as mentioned above in relation to block 102.
  • the method may determine object generation instructions without a ‘interior surface’ modification.
  • other object generation instructions such as instructions for the application of energy, may be determined, and may be modified for identified interior surfaces relative to other surfaces.
  • the method may be performed for a plurality of points of a surface of the object model.
  • the plurality of points may be selected to provide a sample of points substantially representing all the surfaces of the object model data, so that the whole of the surfaces object model can be classified as interior or non-interior (or ‘other’).
  • at least a part of the process of determining object generation instruction may be different for identified interior surfaces than for other surfaces.
  • Figure 2 is an example of a method, which may comprise a computer implemented method for determining the first separation and the second separation, and may be an example of blocks 106 and 108 of Figure 1.
  • Figures 3A to 3D provide an illustration of an example of the method described in relation to Figure 2.
  • the method comprises, in block 202 determining a distance to a nearest object surface.
  • the distance is the distance from the first point, described in relation to the method Figure 1 , and the determined distance is the shortest, straight-line distance between the first point and the nearest object surface, which does not intersect any part of any object model in the arrangement of objects.
  • the method comprises, in block 204 determining a midpoint between nearest object surfaces based on points with maxima in the determined distances.
  • the method comprises, in block 206 determining boundaries between regions by identifying the midpoints as points on a boundary.
  • Blocks 202, 204 and 206 may be performed for each of a plurality of points in the plane.
  • the method comprises, in block 208 dividing a plane into regions, wherein the boundary separates regions, and the boundary is equidistant between the nearest objects to be generated.
  • the method comprises, in block 210 determining the first separation, wherein the first separation is a distance between the first point and a second point on the opposing object surface.
  • the opposing object surface faces the first object surface, and the most direct path, or shortest straight path, between the first point and the second point is free from object models.
  • the method comprises, in block 212, determining the second separation as being the distance between the first point and the nearest point on a boundary.
  • the method may then continue, as indicated by arrow 214, to return to block 202, wherein the method is performed for a different point on the surface of the first object. In this way the method is performed for each of a plurality of points on the surface of the first object model to determine whether each surface is an interior surface.
  • the loop can include performing blocks 104 to 112 for each point on a surface of the object, so that each point is categorised as being on an interior surface.
  • the method may also comprise performing the method for each of a plurality of objects to be generated in the additive manufacturing operation.
  • Figure 3A is a representation of a two-dimensional slice, or plane, through a number of objects to be generated in additive manufacturing and may correspond to a portion of a layer of build material to be deposited in an additive manufacturing operation.
  • the objects to be generated are eight treble clef symbols. Areas in the figure which are black represent regions which are to be solidified and regions which are white remain unsolidified.
  • Figure 3B is a representation of the same plane shown in Figure 3A, with darker shading representing points which have a lower distance to a nearest object surface and points with a lighter shading representing points which have a greater distance from the nearest object surface.
  • the distance to the nearest object model has been determined for each point in the plane, and shaded accordingly.
  • the distance to the nearest object may not be determined for every point, and may instead be determined for a sample of points.
  • identifying the midpoints comprises identifying points which do not have a closest object (i.e. are equidistant between objects). This may be achieved by labelling each object, then iteratively propagating the assigned labels as the minimum distance to an object surface is determined for each point in the plane i.e. label the points immediately adjacent the object with the label corresponding to that object, then label the points immediately adjacent to those points with the same label, until a point is reached which is not closest to that object. The points in the plane which remain unlabelled are then identified as midpoints.
  • FIG. 3C is a further illustration of the plane, wherein the lightness of each point represents the distance from the nearest boundary. Darker shading represents smaller distance to a boundary, whereas lighter shading represents larger distance to a boundary. As can be seen the boundaries of the regions are shaded in darker and points near the centre of regions are shaded relatively lightly. In practice the distance may not be determined for each point in the plane as depicted in Figure 3D, and may be determined for a subset of points on the surfaces of object models.
  • the comparison performed in block 110 may comprise comparing the values for the first separation to the distance represented by the shading in Figure 3D.
  • the first point 302 is at the top of an object model to be generated and the first separation will be the distance to the bottom of the object model directly above it.
  • the second distance will be the distance to the nearest boundary, which in this example is smaller than the first distance so the method would classify this point as not being on an interior surface.
  • the first distance is the distance from the second point 304 to a point on the ‘tail’ of the treble clef. It can be seen that this distance is smaller than the distance to the nearest boundary, and so this would be classified as a point on an interior surface.
  • Figure 4 is an example of a method, which may comprise a computer implemented method for use in determining object generation instructions in which a geometrical compensation is to be applied to a model of a build volume, and may be a continuation of the method of Figure 1 or Figure 2 (i.e. performed after block 112 of Figure 1).
  • the method comprises, as described below in relation to blocks 402 to 404, determining a geometrical compensation to be applied to the first object model.
  • Determining the geometrical compensation may comprise adjusting a value of geometrical compensation to be applied to interior surfaces relative to a value of geometrical compensation to be applied to other surfaces (i.e. exterior surfaces or interior surfaces having a relatively significant spacing).
  • the identified interior surfaces may behave differently to other surfaces when generating the objects and when the generated objects are cooling. For example, they may have higher peak temperatures and remain at higher temperatures for longer relative to other surfaces. Higher temperatures can result in increased growth of an object surface relative to its intended dimensions, as more build material adheres to the surface as it is at a higher temperature, and slower cooling may result in different shrinkage behaviour.
  • maintaining an object at a higher temperature for a longer period of time can cause additional growth on an interior surface of the object and/or in some examples, shrinkage of an object when cooling may induce complex and/or irregular surface tensions on an interior surface of an object which may cause warping which could affect the final shape of the object when cooled. Therefore, to improve the dimensional accuracy of an object the geometrical compensation applied to interior surfaces may be different to the geometrical compensation applied to other surfaces.
  • the method comprises, in block 402 determining a first value of geometrical compensation for surfaces of the first object model.
  • the geometrical compensation to be applied to an exterior surface is determined, for example, by determining scaling and/or offsets to be applied to the object model.
  • the method comprises, in block 404 determining an adjusted value of geometrical compensation for points on an identified interior surface.
  • the geometrical compensation to be applied to an identified interior surface is determined from the geometrical compensation to be applied to other surfaces, for example by applying an additional scaling or offset.
  • the adjusted value may correspond to a reduction in a dimension of the object relative to the same dimension when the corresponding first value is applied to that dimension.
  • a negative scaling or erosion i.e. negative offset
  • the dimension which is reduced may be a dimension which decreases when less build material is used in the object, for example the dimension may be a thickness of material.
  • dimensions which measure an absence of material such as gaps, clearances or holes (e.g. diameters, radii, circumferences, or cross sectional areas thereof), may be increased by the geometrical compensation associated with the adjusted value.
  • a modified, or different, offset for example of around 50 microns may be added to identified interior surfaces.
  • a ‘standard’ offset O to be applied may be applied to identified interior surfaces.
  • the constant C may be replaced with a modification parameter which is a function of object model being generated or the conditions during an/or after the object generation process.
  • the modification parameter may be a function of the predicted object temperature, the volume of the object or distance from a surface to another interior surface.
  • the method comprises, in block 406 applying the adjusted value of geometrical compensation to interior surfaces, and in block 408 the method comprises applying the adjusted value of geometrical compensation to other surfaces.
  • the method comprises, in block 410 generating the first object using object generation instructions based on the modified object model data.
  • a plurality of objects are generated within the object generation operation.
  • generating the object(s) may comprise forming a layer of build material, applying print agent(s), for example through use of ‘inkjet’ liquid distribution technologies in locations specified in object model data to which the first and adjusted compensation has been applied for an object model slice corresponding to that layer using at least one print agent applicator, and applying energy, for example heat, to the layer.
  • Determination of the object generation instructions may comprise determination of amount(s) of print agents to be applied to each location.
  • Figure 5 shows an example of apparatus 500 comprising processing circuitry 502, the processing circuitry 502 comprising, a partition module 504, an object distance module 506, a boundary distance module 508, a classification module 510 and an instruction determination module 512.
  • the partition module 504 partitions a plane of a virtual fabrication chamber modelling objects to be generated in an additive manufacturing operation into regions, each region comprising part of an object to be generated in additive manufacturing, wherein each position in a region is closer to the object in that region than objects in other regions.
  • the part of an object in a region may correspond to a slice through the object, which will be generated in a layer of build material.
  • the regions may be determined, for example as described in relation to Figures 1 , 2 and 3A-D.
  • the object distance module 506 determines a first distance between a position on a surface of a first object in a first region and a second surface of an object, wherein the second surface faces the first surface and is a surface next closest to the position.
  • a surface may be considered to face another surface when their exterior normals are within a predetermined angle of each other, or when a straight line may be drawn between them without intersecting an object. Therefore, the object distance module 506 may determine the first distance as described with respect to Figures 1 or 2.
  • the boundary distance module 508 is to determine a second distance between the position on the surface of the first object and a region boundary nearest to the first object. Unlike the first distance, the second distance may be a distance which intersects an object.
  • the classification module 510 is to classify the position as an internal position by comparing the first distance and the second distance.
  • An internal position may be a position on an interior surface, wherein the spacing between surfaces is relatively small.
  • the classification module 510 classifies a position as an internal position when the first distance is less than the second distance, and not otherwise.
  • the instruction determination module 512 is to determine object generation instructions based on the classification of the position. For example when the position is classified as an internal position (or as being on an internal/interior surface), a modification to the process of determining object generation instructions may be applied for that position. For example, positions which are classified as internal positions may have a geometrical compensation applied which differs to any geometrical compensations which may be otherwise applied, and/or which may be applied to other positions/surfaces of the object model. In other examples, a modification may be applied in the determination of print agents which are to be applied in generating an object.
  • Figure 6 shows an example of apparatus 600, which comprises the processing circuitry 602, which comprises the partition module 506, the object distance module 506, the boundary distance module 508 and the classification module 510 of Figure 5.
  • the processing circuitry 602 of apparatus 600 further comprises an instruction determination module 604 which comprises a modification module 606.
  • the instruction determination module 604 may act as instruction determination module 512 of Figure 5.
  • the instruction determination module 604 also comprises modification module 604 which, in use of the apparatus 600, is to apply a first geometrical transformation to positions within the object model which are classified as internal positions and apply a second geometrical transformation, different to the first geometrical transformation, to at least one other position within the object model to obtain modified object model data.
  • the geometrical compensations may be applied by the modification module 606 as described in relation to blocks 406 and 408 of Figure 4.
  • the apparatus 600 further comprises an additive manufacturing apparatus 608 to generate objects based on the modified object model data.
  • the instruction determination module 512 in use of the additive manufacturing apparatus, determines object generation instructions for generating the objects using the object model to which geometrical transformation(s) has/have been applied.
  • the object generation instructions may, in use thereof, control the additive manufacturing apparatus 608 to generate each of a plurality of layers of the object. This may for example comprise specifying area coverage(s) for print agents such as fusing agents, colorants, detailing agents and the like.
  • object generation parameters are associated with object model sub-volumes (voxels or pixels), and may be based on a modified object model if a geometrical transformation has been applied.
  • the object generation instructions comprise a print agent amount associated with sub-volumes.
  • other parameters such as any, or any combination of heating temperatures, build material choices, an intent of the print mode, and the like, may be specified.
  • halftoning may be applied to determine where to place fusing agent or the like.
  • the additive manufacturing apparatus 608 may, in use thereof, generate an object in a plurality of layers (which may correspond to respective slices of an object model) according to the object generation instructions. For example, this may comprise generating at least one object in a layer-wise manner by selectively solidifying portions of layers of build material. The selective solidification may in some examples be achieved by selectively applying print agents, for example through use of ‘inkjet’ liquid distribution technologies, and applying energy, for example heat, to the layer.
  • the additive manufacturing apparatus 608 may comprise additional components not shown herein, for example any or any combination of a fabrication chamber, a print bed, printhead(s) for distributing print agents, a build material distribution system for providing layers of build material, energy sources such as heat lamps and the like.
  • Figure 7 shows a machine readable medium 702 associated with a processor 704.
  • the machine readable medium 702 comprises instructions 706 which, when executed by the processor 704, cause the processor 704 to carry out tasks.
  • the instructions 706 comprise instructions 708 to cause the processor 704 to, for a representation of an intended fabrication chamber content in additive manufacturing, calculate a minimum first distance between a first object surface of an object model representing a first object and a second object surface, wherein the path between the first object surface and the second object surface does not intersect a representation of material which is intended to be solidified.
  • the instructions 706 further comprise instructions 710 to cause the processor 704 to divide a plane through the object model into regions separated by a boundary equidistant between object surfaces in the plane.
  • Each region may comprise parts of a single object to be generated, and each location within a region may be closer to the object in that region than objects in other regions.
  • the instructions 706 further comprise instructions 712 to cause the processor 704 to calculate a minimum second distance between the first object surface and a boundary separating the regions.
  • the minimum second distance may be the shortest distance between the surface and its nearest boundary. The second distance may be determined, for example as described in relation to block 108 of Figure 1 and blocks 202 to 212 of Figure 2.
  • the instructions 706 further comprise instructions 714 to cause the processor 704 to determine if the surface is an internal surface. When the first distance is less than the second distance, the surface is identified as an internal surface.
  • the instructions are to classify each surface as an internal surface or not. The different categories of surfaces may then be treated differently to account for the different thermal environments which they experience in order to improve dimensional accuracy, for example as described with respect to Figure 4.
  • Figure 8 shows a machine readable medium 802 associated with a processor 704.
  • the machine readable medium 802 comprises instructions which, when executed by the processor 704, cause the processor 704 to carry out instructions 804.
  • the instructions 804 comprise instructions 708 to instruction 714 as described in relation to Figure 7.
  • the instructions 804 further comprise instructions 806 to create modified object model data by applying a first transformation to surfaces not identified as internal surfaces and a second transformation to surfaces identified as internal surfaces, wherein the first transformation and the second transformation are different.
  • the second transformation may be derived from the first transformation.
  • second transformation may comprise applying the first transformation then applying an additional transformation.
  • the instructions 804 further comprise instructions 808 to generate the object based on the modified object model data.
  • the machine-readable medium 702, 802 of Figures 7 or 8, or another machine-readable medium may be provided with instructions to cause a processor 704 to carry out any of the blocks of Figures 1 , 2 or 4.
  • the machine-readable medium 702, 802 of Figures 7 or 8, or another machine-readable medium may comprise instructions to provide the partition module 504, the object distance module 506, the boundary distance module 508, the classification module 510, the instruction determination module 512, 604 and/or the modification module 606.
  • Examples in the present disclosure can be provided as methods, systems or machine readable instructions, such as any combination of software, hardware, firmware or the like. Such machine readable instructions may be included on a computer readable storage medium (including but not limited to disc storage, CD-ROM, optical storage, etc.) having computer readable program codes therein or thereon.
  • a computer readable storage medium including but not limited to disc storage, CD-ROM, optical storage, etc.
  • FIG. 1 The present disclosure is described with reference to flow charts and/or block diagrams of the method, devices and systems according to examples of the present disclosure. Although the flow diagrams described above show a specific order of execution, the order of execution may differ from that which is depicted. Blocks described in relation to one flow chart may be combined with those of another flow chart. It shall be understood that each block in the flow charts and/or block diagrams, as well as combinations of the blocks in the flow charts and/or block diagrams can be realized by machine readable instructions.
  • the machine readable instructions may, for example, be executed by a general purpose computer, a special purpose computer, an embedded processor or processors of other programmable data processing devices to realize the functions described in the description and diagrams.
  • a processor or processing apparatus may execute the machine readable instructions.
  • functional modules of the apparatus for example, any of the partition module 504, the object distance module 506, the boundary distance module 508, the classification module 510, the instruction determination module 512, 604 and/or the modification module 606
  • devices may be implemented by a processor executing machine readable instructions stored in a memory, or a processor operating in accordance with instructions embedded in logic circuitry.
  • the term ‘processor’ is to be interpreted broadly to include a CPU, processing unit, ASIC, logic unit, or programmable gate array etc.
  • the methods and functional modules may all be performed by a single processor or divided amongst several processors.
  • Such machine readable instructions may also be stored in a computer readable storage that can guide the computer or other programmable data processing devices to operate in a specific mode.
  • Such machine readable instructions may also be loaded onto a computer or other programmable data processing devices, so that the computer or other programmable data processing devices perform a series of operations to produce computer-implemented processing, thus the instructions executed on the computer or other programmable devices realize functions specified by block(s) in the flow charts and/or block diagrams.
  • teachings herein may be implemented in the form of a computer software product, the computer software product being stored in a storage medium and comprising a plurality of instructions for making a computer device implement the methods recited in the examples of the present disclosure.

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  • Engineering & Computer Science (AREA)
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  • Mechanical Engineering (AREA)
  • Optics & Photonics (AREA)

Abstract

Procédé consistant à obtenir, par un ensemble circuit de traitement, un modèle d'une chambre de fabrication caractérisant un agencement spatial de modèles d'objet, les modèles d'objet représentant des objets à générer dans une première opération de fabrication additive ; à identifier, à l'aide d'un ensemble circuit de traitement, un premier point sur une première surface d'objet d'un premier modèle d'objet ; à déterminer une première séparation entre le premier point et une surface d'objet opposée ; à déterminer une seconde séparation entre le premier point et une limite qui est équidistante entre la première surface d'objet et une surface d'un second modèle d'objet représentant un second objet ; à identifier des surfaces intérieures par détermination, lorsque la première séparation est inférieure à la seconde séparation, selon laquelle le point est un point sur une surface intérieure et par détermination d'instructions de génération d'objet, la détermination d'instructions de génération d'objet différant pour une surface intérieure identifiée comparativement à une autre surface. La compensation des déformations anticipées est assurée.
PCT/US2020/032461 2020-05-12 2020-05-12 Identification de surfaces intérieures Ceased WO2021230858A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140107823A1 (en) * 2012-10-11 2014-04-17 University Of Southern California 3d printing shrinkage compensation using radial and angular layer perimeter point information
US20170368753A1 (en) * 2016-06-27 2017-12-28 General Electric Company System and method for distortion mitigation and compensation in additive manufacturing proccesses through b-spline hyperpatch field
US20170372480A1 (en) * 2016-06-28 2017-12-28 University Of Cincinnati Systems, Media, and Methods for Pre-Processing and Post-Processing in Additive Manufacturing
US20180169948A1 (en) * 2015-06-12 2018-06-21 Materialise N.V. System and method for ensuring consistency in additive manufacturing using thermal imaging
WO2019078813A1 (fr) * 2017-10-16 2019-04-25 Hewlett-Packard Development Company, L.P. Imprimante 3d

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140107823A1 (en) * 2012-10-11 2014-04-17 University Of Southern California 3d printing shrinkage compensation using radial and angular layer perimeter point information
US20180169948A1 (en) * 2015-06-12 2018-06-21 Materialise N.V. System and method for ensuring consistency in additive manufacturing using thermal imaging
US20170368753A1 (en) * 2016-06-27 2017-12-28 General Electric Company System and method for distortion mitigation and compensation in additive manufacturing proccesses through b-spline hyperpatch field
US20170372480A1 (en) * 2016-06-28 2017-12-28 University Of Cincinnati Systems, Media, and Methods for Pre-Processing and Post-Processing in Additive Manufacturing
WO2019078813A1 (fr) * 2017-10-16 2019-04-25 Hewlett-Packard Development Company, L.P. Imprimante 3d

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