WO2020222781A1 - Compensations géométriques - Google Patents

Compensations géométriques Download PDF

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Publication number
WO2020222781A1
WO2020222781A1 PCT/US2019/029826 US2019029826W WO2020222781A1 WO 2020222781 A1 WO2020222781 A1 WO 2020222781A1 US 2019029826 W US2019029826 W US 2019029826W WO 2020222781 A1 WO2020222781 A1 WO 2020222781A1
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WIPO (PCT)
Prior art keywords
objects
compensation
dimensions
geometrical
generated
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PCT/US2019/029826
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English (en)
Inventor
Enrique GURDIEL GONZALEZ
Jordi SANROMA GARRIT
Quim MUNTAL DIAZ
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Hewlett-Packard Development Company, L.P.
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Application filed by Hewlett-Packard Development Company, L.P. filed Critical Hewlett-Packard Development Company, L.P.
Priority to PCT/US2019/029826 priority Critical patent/WO2020222781A1/fr
Publication of WO2020222781A1 publication Critical patent/WO2020222781A1/fr

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Classifications

    • 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
    • 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
    • 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
    • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • 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
    • B33Y50/02—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T19/00—Manipulating 3D models or images for computer graphics
    • G06T19/20—Editing of 3D images, e.g. changing shapes or colours, aligning objects or positioning parts
    • 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
    • B22F10/20—Direct sintering or melting
    • B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2219/00—Indexing scheme for manipulating 3D models or images for computer graphics
    • G06T2219/20—Indexing scheme for editing of 3D models
    • G06T2219/2021—Shape modification
    • 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 method of determining a geometrical compensation for additive manufacturing
  • Figure 2A shows an example of a particular object oriented in an object generation orientation
  • Figures 2B-2D show examples of data for use determining a geometrical compensation for additive manufacturing for multiple instances of the object shown in Figure 2A;
  • Figure 3 is a flowchart of another example method of determining a geometrical compensation
  • Figures 4 and 5 are simplified schematic drawings of example apparatus for additive manufacturing.
  • Figure 6 is a simplified schematic drawing 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’
  • a fusing agent may be selectively distributed onto portions of a layer of build material in a pattern derived from data representing a slice of a three-dimensional object to be generated (which may for example be generated from structural design data).
  • 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 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 V1 Q60A“HP fusing agent” available from HP Inc.
  • a fusing agent may comprise at least one of an infra-red light absorber, a near infra-red light absorber, a visible light absorber and a UV light absorber.
  • print agents comprising visible light 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 to an object, and such agents may therefore be termed detailing agents.
  • detailing agent may be used near edge surfaces of an object being printed, for example to reduce or prevent fusing from occurring in that region through‘thermal bleeding’.
  • a suitable detailing agent may be a formulation commercially referred to as V1 Q61A“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 generating 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 can be processed to derive slices of 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.
  • Figure 1 is an example of a method, which may comprise a computer implemented method for determining a geometrical compensation for use in modifying object model data. For example, such a compensation may be used to modify of object model data in order to compensate for anticipated departures from intended dimensions when generating an object.
  • 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 to compensate for such growth.
  • objects may be smaller following object generation than is specified in object model data.
  • a geometrical compensation/transformation model may specify at least one geometrical compensation parameter to in turn specify how an object volume in object model data should be increased to compensate for the anticipated reduction in size.
  • a particular object may be subject to mechanisms which result in growth and/or shrinkage, and the actual compensation applied may be influenced by the different degrees to which an object may be affected by such processes.
  • the method may make use of data gathered from a set of objects generated using an additive manufacturing process.
  • these objects may be generated using the same class of additive manufacturing process (for example, all the objects may be generated using selective laser sintering, or all the objects may be generated using a fusing agent printed onto a layer of build material, or all the objects may be generated using some other additive manufacturing process).
  • all the objects may be generated using a particular class of apparatus (for example, a powder and fusing agent based 3D printing system).
  • all the objects may be generated using the same instance of an additive manufacturing apparatus (i.e. a particular 3D printer).
  • the method comprises, in block 102, acquiring, by at least one processor, an indication of measured dimensions of at least one object generated in at least one additive manufacturing build operation. This may comprise acquiring an indication of the measurements themselves, in some examples along with the intended or ‘nominal’ measurements. In some examples, the indications may comprise indications of how measurements depart from the expected (or nominal) measurement. For example, these dimensions may be measured by a 3D scanner, manually, optically, automatically or in some other way.
  • the method may comprise measuring objects generated using additive manufacturing in order to acquire the measurements.
  • the objects may be measured separately, and the data provided for example from a memory or over a communications link or the like.
  • the method may comprise generating the objects themselves using an additive manufacturing process.
  • Block 104 comprises acquiring, by at least one processor (which may be the same processor(s) as referred to in relation to block 102), an indication of the orientation of the measured dimensions during the additive manufacturing build operation.
  • the indication of the orientation may be derived from object model data, or from data indicating an object generation location or orientation.
  • a fabrication chamber may be characterised as having X, Y and Z axes. By convention, an object may be formed in XY layers, increasing in height along the Z axis.
  • a ‘virtual’ fabrication chamber i.e. a model of the intended content of a fabrication chamber
  • specifying intended locations for object(s) in object generation may be devised prior to generating the object(s).
  • the location of the object vertices of‘virtual objects’ arranged in the virtual fabrication chamber may be specified as XYZ coordinates, and the coordinates may provide an indication of the orientation of a particular object dimension.
  • the orientations may be specified directly.
  • the object is rotated such that a measurement which may be associated with the height of the object is non-vertical during object generation.
  • a measurement which may be associated with the height of the object is non-vertical during object generation.
  • an object may be generated 20° off vertical, with X, Y and/or Z components of the rotation being specified.
  • the dimensions under consideration in the object model may be‘projected’ onto the different axes (using, for example a cosine decomposition), and the ratio for the lengths of the projections may be used to determine an orientation.
  • the indication of the orientation may be provided directly, or may be derived from or implicit in data such as data describing how the object may be oriented in object generation.
  • Block 106 comprises determining, by at least one processor (which may be the same processor(s) as referred to in relation to blocks 102 and/or 104), a vector decomposition based (at least in part) on the indication of orientation.
  • Vector decomposition is the process of describing a single vector as at least two‘component’ vectors which may be summed to the original vector.
  • determining the vector decomposition may comprise determining the vector components of a measured dimension.
  • Block 108 comprises determining, by at least one processor, (which may be the same processor(s) as referred to in relation to blocks 102, 104 and/or 106), a geometrical compensation for use in modifying object model data based (at least in part) on the measured dimensions and the vector decomposition (of the vector components).
  • the components of the vector decomposition may be used in determining the geometrical compensation.
  • measured dimensions which are not aligned to a given axis may be used to determine a compensation value to be applied in a particular axis.
  • Figure 2A shows an example of an object 200 showing its object generation orientation in a fabrication chamber.
  • Three dimensions which may be measured to provide the measured dimensions of block 102 are marked as A, B and C.
  • B is aligned with the Y axis, whereas A and C extend in the XZ plane, with A having a greater horizontal component and C having a greater vertical component. Therefore, both A and C are non-parallel to at least one axis.
  • the measurements may be decomposed down as follows:
  • the magnitude of the vector components of the nominal measurements may be determined using the orientation where it is provided, or the vector components may be determined by projecting the object model data onto the axes, and used to determine the orientation.
  • Measured data as described in relation to block 102 may be acquired for a set of objects- for example hundreds of such objects.
  • Figure 2B-D show examples of measurement distributions of the measurements A, B and C for a plurality of objects having the form shown in Figure 2A, and printed in the same orientation. In this particular example, the objects were printed in a single build operation, which comprised objects of this form, and no other types of object.
  • Figures 2B, 2C and 2D show the number of measured dimensions falling into 0.01 mm resolution bins. It may be noted that, if more measurements were acquired (from this object or another object, or indeed from the same object in a different orientation, which measurements may be treated separately as the processes resulting in deformation are not isotropic), this may result in additional error distributions.
  • Deviations from intended dimensions may be characterised as :
  • the A and C dimensions are generally larger than intended, the B dimension is generally smaller than is intended. It may be noted that the C population is relatively spread. This is an attribute of some additive manufacturing apparatus, where the greatest inaccuracy may be seen in the Z dimension, noting that the Z component of C is relatively large.
  • the Figures also show lines marking a 0.2mm tolerance band.
  • the compensation derived in this example is intended to centre the measurement distributions on the nominal, or expected, dimensions.
  • an‘optimisation problem’ may be solved.
  • the optimisation is carried out to determine the parameters (i.e. geometrical compensation values) of a compensation that reduce the bias of the measured error distributions (i.e. the parameters which provide an error distribution having a mean equal to 0, or a measurement distribution having a mean equal to the nominal for the measurements).
  • the geometrical compensation values may comprise scaling and/or offset factors in each of the X, Y and Z axes.
  • a scaling factor may be used to multiply all specified dimensions in the direction of an axis by a value, which may be greater than 1 in order to increase the dimensions and less than 1 to reduce the dimensions.
  • An offset factor may specify, for example by a specified distance (which may be specified in predefined units, for example in millimetres, or in addressable units such as pixels or‘voxels’), an amount to add or remove from a surface of the object (or a perimeter within a layer). For example, a distance as measured in the direction of a normal from the object surface may be specified and the object may be eroded or dilated (i.e., inflated or enlarged) by this distance.
  • the scaling factor in relation to that dimension may be set to 1 , and if no offset is indicated in a given dimension, the offset factor in relation to that dimension may be set to 0.
  • a scale correction may be represented as a factor of s and an offset correction with a length of o as follows:
  • M is the acquired measurement (i.e., the measured dimension) and M’ the value with the transformations simulated.
  • the components of the vector decomposition may be multiplied with measured dimensions to determine the magnitude of a measurement along an axis. When generalised to three dimensions, this can be expressed as:
  • orientation of the nominal measurements and provides the magnitudes of the vector component of the measured dimensions.
  • this relationship may be solved to find s and o such that M’ is, at least on average, the nominal, or expected, dimension.
  • the equation may be solved to determine geometrical compensation values of sx, sy, sz, ox, oy and oz which minimize the mean, with respect to the identified dimensions, of the squared differences between the nominal measurement and the mean value of the predicted measurement distribution, giving, in the example of the Figures:
  • Such scaling factors and offset factors may be used in a subsequent build operation to generate a further set of objects which may be closer to the intended dimensions.
  • bounds may be set.
  • the maximum permissible change in scale is 0.1 (i.e. the scale may be at most 1.1000 or 0.9000) and the maximum permissible change in offset is ⁇ 0.1500mm.
  • Other bounds may be set in other examples.
  • scale could be set to 1 for at least one axis and/or the offset could be set to 0. This may decrease the processing resources utilised.
  • offset factor is specified herein as a distance in millimetres, it may be specified in some other way, for example in terms of voxels.
  • Offset and/or scale parameters may be used to derive offset and/or scale parameters, for example including those which seek to minimise the distribution of the measurements, solutions which penalise measurement sets having a high number of anomalous measurements (e.g. those outside of a threshold range of the nominal), solutions which favour a predetermined data spread, for example, those which are within a predetermined tolerance of the mean (even if this shifts the mean away from resulting in the nominal measurement), or some other factor, based on a particular intended outcome.
  • Other methods may use data fitting methods such as linear regression or the like.
  • Figure 3 is an example of a method which may be used in conjunction with the methods discussed above.
  • a build operation is to generate a predetermined set of objects and the geometrical compensation is for use in modifying object model data for a further instance of the build operation.
  • the build operations are intended to generate a plurality of instances of a particular object (referred to as the‘first object’ herein), and all the instances are to be generated in a common orientation. This may simplify data gathering and analysis, and the robustness of the compensation derived, although the method may be used with a range of objects.
  • objects (and/or the orientation thereof) may be relatively similar in applications of the method as this enhances its effectiveness.
  • the volume of objects may be similar, and/or they may have relatively similar forms and relatively similar measured dimensions.
  • Block 302 comprises acquiring object model data representing the first object.
  • the object model data may comprise data representing at least a portion (in some examples, a slice) of an object to be generated by an additive manufacturing apparatus by fusing a build material.
  • the object model data may for example comprise a Computer Aided Design (CAD) model, and/or may for example be a STereoLithographic (STL) data file.
  • CAD Computer Aided Design
  • STL STereoLithographic
  • the object model data may represent the object or object portion as a plurality of sub-volumes, wherein each sub-volume represents a region of the object which is individually addressable in object generation.
  • the sub-volumes may be referred to as voxels, i.e. three-dimensional pixels.
  • the data may be acquired from a memory, or over a network, or the like.
  • Block 304 comprises determining, using at least one processor, at least one dimensional compensation value to apply to the object model data representing the first object.
  • this is not the geometrical transformation derived as described in Figure 1 , but is a different compensation value.
  • the dimensional compensation values may describe a parametrical transformation, for example a geometrical transformation such as at least one of an offset and a scaling factor, for example up to three scaling factors (one for each of the three orthogonal dimensions) and up to three offset factors (one for each of the three orthogonal dimensions).
  • the dimension compensation value may be taken from a geometrical compensation model. In examples, such models may map object generation parameters to compensations to apply.
  • a geometrical compensation model may take account of an intended location of an object in a fabrication chamber. It has been noted that dimensional deformation has a relationship to the location of object generation, and therefore different compensation parameters may be applied for different object locations to improve accuracy. Such geometrical compensation models may therefore comprise or provide compensation parameters which may be mapped to the intended location of an object (which may for example be a single identifiable point such as the location of the centre of mass of the object, or may include a consideration of the volumetric extent of the object). [0050] For example, if an object is to be generated at a first location within the fabrication chamber, the location may be mapped to a geometrical compensation comprising one or more offset and/or scaling value.
  • this second location may be mapped to a different geometrical compensation comprising one or more different offset and/or scaling value.
  • the particular geometrical compensation applied may vary between different locations based on predetermined mappings or the like.
  • At least one geometrical compensation model may comprise a plurality of defined geometrical compensation values (or value sets), each associated with different locations within the fabrication chamber.
  • a particular geometrical compensation value may be selected based (at least in part) on the intended object generation location.
  • defined locations may be associated with geometrical compensation value(s), and the geometrical compensation value(s) to apply at locations intermediate to such defined locations may be generated for example by interpolation, or by selection of the closest defined location, or the like.
  • characteristics of the object such as consideration of the object volume and/or surface area, may be used as input parameters in a geometrical compensation model.
  • a first compensation model may comprise a compensation value associated with object volume while in other examples there may be no such compensation value, or a different compensation value may be used.
  • the surface area may be used to determine how‘solid’ an object is.
  • the amount of solid material in an object may be used to predict how the object may deform. For example, a more solid object may tend to accumulate more heat than a less solid object in a thermal fusing additive manufacturing operation and may cool differently. Such object generation parameters may therefore be mapped to different geometrical compensation parameters within a geometrical compensation model.
  • Other geometrical compensation models may for example include a consideration of how many objects are to be generated in a fabrication chamber and/or the proximity of the objects (for example in terms of‘packing density’).
  • object generation parameter values (which may be object generation parameter values which are configurable or selectable by a user or operator) may be considered.
  • the object generation parameter(s) may be any parameter which may have an impact on dimensional inaccuracy.
  • the object generation parameter(s) may comprise any, or any combination of, environmental conditions, object generation apparatus, object generation material composition (which may comprise selection of the type or composition of build material and/or print agents), object cooling profile, print mode, or the like. These may be specified, for example, by input to at least one processor.
  • object generation material composition which may comprise selection of the type or composition of build material and/or print agents
  • object cooling profile print mode
  • print mode print mode
  • different geometrical compensation models and/or different parameters may be provided for different apparatus, different print modes, different cooling profiles or the like.
  • the geometrical compensation parameter(s) and/or geometrical compensation model(s) specifying such parameters may for example be stored in a memory, for example embodied as a mapping resource(s) such as lookup tables and the like, or may be embodied as one or more algorithm, for example relating object generation parameter(s) (e.g. any or any combination of object generation location, volume, surface area, packing density, environmental conditions, object generation apparatus, object generation material composition, object cooling profile or print mode) to a compensation to be applied to object model data.
  • object generation parameter(s) e.g. any or any combination of object generation location, volume, surface area, packing density, environmental conditions, object generation apparatus, object generation material composition, object cooling profile or print mode
  • Block 306 comprises modifying the object model data with the determined compensation.
  • different modifications may be carried out with respect to different intended instances of the first object, for example based on an object generation parameter as set out above.
  • Block 308 comprises determining object generation instructions (or‘print instructions’) based on (at least in part) the modified object model data.
  • the object generation instructions in some examples may specify an amount of print agent to be applied to each of a plurality of locations on a layer of build material.
  • generating object generation instructions may comprise determining‘slices’ of a virtual fabrication chamber (or build volume) comprising virtual object(s) (to which a modification may have been applied) and rasterising these slices into pixels (or voxels, i.e. three- dimensional pixels).
  • An amount of print agent (or no print agent) may be associated with each of the pixels/voxels.
  • the object generation instructions may be determined to specify that fusing agent should be applied to a corresponding region of build material in object generation. If however a pixel relates to a region of the fabrication chamber which is intended to remain unsolidified, then object generation instructions may be determined to specify that no agent, or a coalescence modifying agent such as a detailing agent, may be applied thereto, for example to cool the build material.
  • the amounts of such agents may be specified in the determined instructions and these amounts may be determined based on, for example, thermal considerations and the like.
  • object generation instruction may specify how to direct directed energy, or how to place a curing or binding agent or the like.
  • Block 310 comprises generating the set of instances of the first object in a common build operation.
  • Generating the objects may comprise generating the objects based on object generation instructions (or‘print instructions’).
  • the objects may be generated layer by layer.
  • this may comprise forming a layer of build material, applying print agents, for example through use of ‘inkjet’ liquid distribution technologies in locations specified in the object generation instructions 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.
  • Some techniques allow for accurate placement of print agent on a build material, for example by using print heads operated according to inkjet principles of two-dimensional printing to apply print agents, which in some examples may be controlled to apply print agents with a resolution of around 600dpi, or 1200dpi.
  • a further layer of build material may then be formed and the process repeated, for example with the object generation instructions for the next slice.
  • objects may be generated using directed energy, or through use of chemical binding or curing, or in some other way.
  • Block 312 comprises measuring predetermined object dimensions. For example, these dimensions may be measured by a 3D scanner, manually, optically, automatically or in some other way.
  • Block 314 comprises determining a geometrical compensation for use in modifying object model data based on measured dimensions and the vector decomposition, for example as described above with respect to Figure 1 and 2A-D.
  • Block 316 comprises combining the geometrical compensation determined in block 314 with the dimension modification determined in block 304, and to use this combination to modify object model data representing the first object for a subsequent build operation.
  • the determined geometrical compensation is used to correct a geometrical compensation used to generate the measured objects.
  • multiple batches of the first object are to be generated.
  • the method may therefore comprise using the object model data to determine a further set of object generation instructions and generating a further set of objects. By using the methods set out herein, subsequent batches may conform better to intended dimensions.
  • a single or common defined modification may be applied.
  • a geometrical compensation model used to generate the objects in block 310 may result in different modifications being made to object model data, the change to that model may be consistent for all objects.
  • a location dependent model may specify a scale and offset factor in a given axis of s, and o, for location i and of s and o for location j, but both of these may be modified by the same ‘correction’ to result in Si * s new and Oi+o new for location i and S j * s new and O j +o new for location j. This may compensate well for ‘shifts’ in object dimension accuracy, in which a particular apparatus and/or object may result in a consistent offset compared to an expectation given a general compensation model.
  • Modelling the complex thermal relationships experienced during object generation is both intellectually and computationally difficult. However, by tailoring a modification based on decomposition of measurements, the range of measurements which may contribute to a compensation model may be increased. Moreover, by tailoring a modification/compensation model to a particular object in a particular orientation, accuracy may be increased.
  • FIG. 4 shows an apparatus 400 comprising processing circuitry 402.
  • the processing circuitry 402 comprises a data acquisition module 404, a vector decomposition module 406 and a geometrical compensation module 408.
  • the data acquisition module 404 acquires data indicative of measured object dimensions for objects generated by an additive manufacturing apparatus. This may for example comprise the measurements themselves, as has been described above, or an indication of the deviation from the expected measurements.
  • the objects may be a set of objects generated in a common operation and/or the objects may be based on the same underlying object model data (albeit possibly modified in different ways).
  • the vector decomposition module 404 decomposes object dimensions into orthogonal axis components. The decomposed object dimensions may be based on the direction of nominal dimensions as oriented in an object generation orientation (e.g.
  • the geometrical compensation module 408 derives a geometrical compensation describing at least one geometrical transformation to be applied to object model data representing objects in the direction of at least one of the orthogonal axes based on the orthogonal axis components.
  • the geometrical compensation specifies at least one of a scaling factor and an offset factor.
  • the geometrical compensation comprises three scaling factors and three offset factors, wherein each of the scaling factors and each of the offset factors is associated with one of three orthogonal axes and wherein the orthogonal axis components are aligned with the orthogonal axes.
  • Figure 5 shows additive manufacturing apparatus 500 to generate an object comprising processing circuitry 502 comprising, in addition to the data acquisition module 404, vector decomposition module 406 and geometrical compensation module 408 of Figure 4, a print instructions module 504 for determining print instructions for generating the object from data representing the modified virtual object.
  • processing circuitry 502 comprising, in addition to the data acquisition module 404, vector decomposition module 406 and geometrical compensation module 408 of Figure 4, a print instructions module 504 for determining print instructions for generating the object from data representing the modified virtual object.
  • the additive manufacturing apparatus may, in some examples, comprise a model modification module to modify object model data representing at least one objects using the determined geometrical compensation(s) to generate at least one object in a subsequent additive manufacturing build operation.
  • common underlying object model data is modified to create modified object model data to generate each of a plurality of instances of a particular object.
  • the subsequent additive manufacturing build operation is to generate multiple instances of the particular object, and no other object.
  • subsequent additive manufacturing build operation is to generate multiple instances of the same object as that from which the measured dimensions were obtained).
  • the multiple instances of the particular object be generated to have a common orientation (which may be the same as the orientation of the objects from which the measured dimensions were obtained).
  • the content of the subsequent build operation may be substantially the same (i.e. comprising of objects generated in the same position, orientation, number and/or having the same form) as the build operation from which the measurements are acquired (albeit in some cases with different modifications made to the underlying object model data).
  • the print instructions module 504 determines print instructions for generating the object from data representing the modified virtual object.
  • the print instructions may, in use thereof, control the additive manufacturing apparatus 500 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).
  • the print 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 500 in use thereof, generates the object in a plurality of layers (which may correspond to respective slices of an object model) according to the print instructions.
  • the additive manufacturing apparatus 500 may for example generate an 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 500 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.
  • the processing circuitry 402, 502 or the modules thereof may carry out any or any combination of the blocks of Figure 1 , and/or any of blocks 302 to 308, 314 or 316 of Figure 3.
  • Figure 6 shows a tangible machine-readable medium 600 associated with a processor 602.
  • the machine-readable medium 600 comprises instructions 604 which, when executed by the processor 602, cause the processor 602 to carry out tasks.
  • the instructions 604 comprise instructions 606 to cause the processor 602 to decompose object dimensions in a first set of 3D printed objects into orthogonal vectors and instructions 608 to determine at least one compensation parameter to apply in the direction of each of the vectors, wherein the compensation parameter is to compensate for deformations in subsequent 3D printing of the set of objects.
  • the at least one compensation parameter may be determined using data indicative of measurements of the dimensions in 3D printed objects.
  • the vector decomposition may be derived from the orientation of the measurements, which may in turn be derived from or provided with object model data.
  • the machine-readable medium 600 may store instructions to carry out any or any combination of the blocks of Figure 1 , and/or any of blocks 302 to 308, 314 or 316 of Figure 3.
  • 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.
  • 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 such as the data acquisition module 404, the vector decomposition module 406 the geometrical compensation module 408 and/or the print instructions module 504
  • 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.
  • 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 in the 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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Abstract

Dans un exemple, le procédé selon l'invention comprend les étapes suivantes : au moins un processeur acquiert une indication de dimensions mesurées d'objets générés dans au moins une opération de construction par fabrication additive, et une indication de l'orientation des dimensions mesurées ; déterminer une décomposition vectorielle sur la base de l'indication de l'orientation ; déterminer une compensation géométrique destinée à être utilisée pour modifier des données de modèle d'objet sur la base des dimensions mesurées et de la décomposition vectorielle.
PCT/US2019/029826 2019-04-30 2019-04-30 Compensations géométriques WO2020222781A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023113823A1 (fr) * 2021-12-17 2023-06-22 Hewlett-Packard Development Company, L.P. Génération d'une représentation tridimensionnelle d'un objet

Citations (3)

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Publication number Priority date Publication date Assignee Title
US20170190124A1 (en) * 2015-12-30 2017-07-06 Airbus Group Sas Device and method for correction of geometrical differences of the surfaces of parts to be assembled at the assembly interface
WO2018194630A1 (fr) * 2017-04-21 2018-10-25 Hewlett-Packard Development Company, L.P. Compensation du rétrécissement d'objets dans une impression en trois dimensions (3d)
WO2018203029A1 (fr) * 2017-05-05 2018-11-08 Sony Interactive Entertainment Inc. Système et procédé de modélisation d'impression 3d

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170190124A1 (en) * 2015-12-30 2017-07-06 Airbus Group Sas Device and method for correction of geometrical differences of the surfaces of parts to be assembled at the assembly interface
WO2018194630A1 (fr) * 2017-04-21 2018-10-25 Hewlett-Packard Development Company, L.P. Compensation du rétrécissement d'objets dans une impression en trois dimensions (3d)
WO2018203029A1 (fr) * 2017-05-05 2018-11-08 Sony Interactive Entertainment Inc. Système et procédé de modélisation d'impression 3d

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023113823A1 (fr) * 2021-12-17 2023-06-22 Hewlett-Packard Development Company, L.P. Génération d'une représentation tridimensionnelle d'un objet

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