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WO2020204911A1 - Melt temperature determination for 3d object generation - Google Patents

Melt temperature determination for 3d object generation Download PDF

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Publication number
WO2020204911A1
WO2020204911A1 PCT/US2019/025353 US2019025353W WO2020204911A1 WO 2020204911 A1 WO2020204911 A1 WO 2020204911A1 US 2019025353 W US2019025353 W US 2019025353W WO 2020204911 A1 WO2020204911 A1 WO 2020204911A1
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WIPO (PCT)
Prior art keywords
temperature
build material
meit
melt
melt temperature
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Ceased
Application number
PCT/US2019/025353
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French (fr)
Inventor
Pol FORNOS MARTINEZ
Ismael FERNANDEZ AYMERICH
Mercedes BLANCO ROLLAN
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Hewlett Packard Development Co LP
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Hewlett Packard Development Co LP
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Priority to PCT/US2019/025353 priority Critical patent/WO2020204911A1/en
Publication of WO2020204911A1 publication Critical patent/WO2020204911A1/en
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
    • B29C64/393—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
    • 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
    • B22F10/30—Process control
    • B22F10/36—Process control of energy beam parameters
    • B22F10/368—Temperature or temperature gradient, e.g. temperature of the melt pool
    • 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
    • B22F10/85—Data acquisition or data processing for controlling or regulating additive manufacturing processes
    • 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
    • B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
    • B22F12/90—Means for process control, e.g. cameras or sensors
    • 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
    • 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
    • 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
    • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • B29C64/255—Enclosures for the building material, e.g. powder containers
    • 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

  • Three-dimensional (3D) objects may be generated by depositing and melting successive layers of a build material; a layer of build material is deposited and then melted before another layer is deposited and melted such that it fuses to the previous layer. This continues layer-by-layer until a complete 3D object has been generated.
  • the quality of 3D objects generated using such methods may vary widely depending on the nature of the build material and the temperature at which it is melted during printing.
  • Figure 1 is an example Differential Scanning Calorimetry (DSC) curve for a build material with a narrow melt temperature range and a sharp melting point.
  • DSC Differential Scanning Calorimetry
  • Figure 2 is an example DSC curve for a build material with a wide melt temperature range that does not have a sharp melting point.
  • Figure 3 is an example plot of temperature increase over time that may be used to determine melt temperature.
  • Figure 4 is a schematic representation of a method for optimising an apparatus for generating a 3D object, wherein the apparatus comprises at least one thermal detector and a processing unit, according to an example.
  • Figure 5 is an example of a method for optimising an apparatus for generating a 3D object.
  • a given build material will have a predicted melt temperature, but the exact melt temperature may vary from batch to batch of build material.
  • some build materials have a narrow melt temperature range and a sharp melting point (see Figure 1 ), whilst others do not (see Figure 2).
  • Melt temperature is a key parameter when printing 3D objects and using an inaccurate melt temperature when processing layers of a build material to generate 3D objects can lead to poor quality products, introduce high variability among different print jobs or even result in print job failure. Therefore, relying on a predicted melt temperature may not be not sufficient to ensure the generation of a good quality product, especially when the build material being used has a wide melt temperature range.
  • the melt temperature of a batch of build material may be determined by fusing a small area of build material whilst using a thermal camera to measure temperature increase over time (see Figure 3), and using the plot of temperature increase over time to determine the melt temperature.
  • this process is time consuming, uses build material that could otherwise be used to generate a 3D object, relies on thermal cameras that may themselves be inaccurate, and is not suited for use with build materials that have a wide melt temperature range.
  • DSC Differential Scanning Calorimetry
  • Melting is an endothermic process in which the material being melted absorbs heat as it undergoes a phase transition from solid to liquid. Therefore, using DSC to measure melt temperature results in melt curves such as the ones in Figures 1 and 2.
  • the DSC curve of a batch of build material may be generated during the quality control testing carried out at the end of the manufacturing process used to prepare a batch of build material.
  • a method of optimising an apparatus for generating a 3D object may comprise obtaining a previously determined DSC melt temperature for a build material (TDsc-meit).
  • the previously determined DSC melt temperature for a build material (TDsc-meit) may be obtained from a storage medium on a build material container, obtained from a network, obtained from user input, or obtained in another secure manner.
  • the previously determined DSC melt temperature (T Dsc-meit) may be derived from the DSC curve generated at the end of the manufacturing process used to prepare a batch of build material.
  • the previously determined DSC melt temperature (TDsc-meit) can be stored on a storage medium on the build material container when the build material is loaded into the container.
  • the storage medium on a build material container may, in one example, be a memory on a build material container.
  • An operational melt temperature (Top-meit) may be calculated using the previously determined DSC melt temperature for the build material (TDsc-meit) and a known temperature variation of at least one thermal detector (Tvar), wherein“temperature variation” refers to the temperature difference between the detected temperature and the actual temperature arising from inaccuracies in the at least one thermal detector.
  • a temperature variation of +3 °C means that a thermal detector is detecting a temperature that is 3 °C higher than the actual temperature.
  • Suitable thermal detectors for use in apparatuses for generating 3D objects include thermal cameras.
  • thermal detectors may be inaccurate, for example the temperature variation readings obtained from the thermal cameras commonly used in apparatuses for generating 3D objects can have a magnitude of 2 °C or more.
  • the known temperature variation of the at least one thermal detector may be based on the temperature variation of the at least one thermal detector as tested during assembly of thermal detectors. Such testing may be carried out using thermal patches.
  • the operation of the apparatus may be adjusted to use the calculated operational melt temperature (Top-meit) so that the apparatus can accurately melt layers of the build material and thereby generate a satisfactory 3D object.
  • An example of such a method is shown in Figure 5.
  • this method allows the optimisation of an apparatus on the basis of the batch of build material being melted and on the basis of the at least one thermal detector being used by the apparatus since the calculated operational melt temperature (Top-meit) is derived from both the previously determined DSC melt temperature for the build material (TDsc-meit) and the known temperature variation of the at least one thermal detector (Tvar).
  • Topic-meit the calculated operational melt temperature
  • Tvar the known temperature variation of the at least one thermal detector
  • This method of optimising an apparatus for generating a 3D object may be a computer- implemented method.
  • Figure 4 is a schematic representation of a method for optimising an apparatus for generating a 3D object in which“batch 1”,“batch 2” and“batch 3” of a build material are manufactured and their DSC curves calculated to result in previously determined DSC melt temperatures for each batch (TDsc-mem ), (TDSC- meit 2) and (T D sc- meit 3).
  • the known temperature variations of the at least one thermal detectors in Apparatus A and Apparatus B are then used with the previously determined DSC melt temperatures for each batch (TDsc-mem ), (T D sc- meit 2) and (Tosc- meit s) to calculate the operational melt temperatures for each batch when used in each printer (T 0p -meitiA), (T 0p -meit2A), (T 0p -meit3A), (T 0p-m eiti B), (T 0p -meit2B) and (T 0p -meit3B).
  • the apparatuses may be printers.
  • One means for calculating an operational melt temperature may comprise adding the previously determined DSC melt temperature for the build material (TDsc-meit) and the known temperature variation of the at least one thermal detector (Tvar) to obtain the operational melt temperature (Top-meit): (TDSC-melt) + (Tvar) — (Top-melt) ⁇
  • a previously determined DSC melt temperature for a build material (T Dsc-meit) of 78 °C and a known temperature variation of a thermal detector (Tvar) of +3 °C will result in an operational melt temperature (Top-meit) of 81 °C.
  • T Dsc-meit a build material
  • Tvar thermal detector
  • Top-meit operational melt temperature
  • a previously determined DSC melt temperature for a build material (TDsc-meit) of 155 °C and a known temperature variation of a thermal detector (Tvar) of -2 °C will result in an operational melt temperature (Top-meit) of 153 °C.
  • Tvar thermal detector
  • Top-meit operational melt temperature
  • Another means for calculating an operational melt temperature may comprise subtracting the previously determined DSC melt temperature for the build material (TDsc-meit) from a predicted melt temperature for the build material (Tmeit) to obtain a first temperature difference (TDsc-ditf); subtracting the first temperature difference (T D sc- ditf ) from the known temperature variation of the at least one thermal detector (Tvar) to obtain a second temperature difference (T var-diff); then adding the second temperature difference (Tvar-dm) to the predicted melt temperature for the build material (Tmeit) to obtain the operational melt temperature (T 0p -meit):
  • the first temperature difference (Tosc- d m) will be positive and vice versa.
  • the operational melt temperature (Top-meit) will be greater than the predicted melt temperature for the build material (T me it) and vice versa.
  • a previously determined DSC melt temperature (Tosc-meit) of 78° C for a build material with a predicted melt temperature (Tmeit) of 80° C will result in a first temperature difference (T D sc- dift ) of +2° C; and a known temperature variation of a thermal detector (Tvar) of +3° C will result in a second temperature difference (Tvar-dift) of +1 ° C, which when added to the predicted melt temperature (Tmeit) of 80° C results in an operational melt temperature (Top-meit) of 81 ° C.
  • a previously determined DSC melt temperature (Tosc-meit) of 155° C for a build material with a predicted melt temperature (Tmeit) of 150° C will result in a first temperature difference (Tosc-ditt) of -5° C; and a known temperature variation of a thermal detector (Tvar) of -2 °C will result in a second temperature difference (Tvar- diff) of +3 °C, which when added to the predicted melt temperature (Tmeit) of 150° C results in an operational melt temperature (Top-meit) of 153° C.
  • Another related means for calculating an operational melt temperature may be adjusted such that it comprises subtracting a predicted melt temperature for the build material (Tmeit) from the previously determined DSC melt temperature for the build material (Tosc-meit) to obtain a first temperature difference (Tosc-ditt); adding the first temperature difference (Tosc-ditt) to the known temperature variation of the at least one thermal detector (Tvar) to obtain a second temperature difference (Tvar-diff); then adding the second temperature difference (T var-diff) to the predicted melt temperature for the build material (Tmeit) to obtain the operational melt temperature (Top-meit):
  • the previously determined DSC melt temperature for the build material (TDsc-meit) may not vary significantly from the predicted melt temperature for the build material (T meit ) and result in a relatively small first temperature difference (TDsc-cn ff ).
  • Tmeit predicted melt temperature for the build material
  • Tmeit when generating a 3D object without optimisation might not be sufficient to ensure the generation of a good quality product due to variability in temperature readings by different thermal detectors (as described above).
  • the second temperature difference (Tvar-dift) may be relatively large even if the first temperature difference (Tosc- diff ) is relatively small.
  • T op-meit All of the above means for calculating an operational melt temperature (T op-meit) will give the same result (for the same previously determined DSC melt temperature (TDsc-meit) and the same known temperature variation (Tvar)) and any other suitable means for calculating an operational melt temperature (Top-meit) will also give the same result.
  • Adjusting the operation of the apparatus to use the calculated operational melt temperature (Top-meit) may comprise instructing the apparatus to apply the calculated operational melt temperature (Top-meit) when melting the build material to generate a 3D object.
  • the apparatus is instructed to apply a temperature of 81 ° C when melting the build material to generate a 3D object
  • the apparatus is instructed to apply a temperature of 153° C when melting the build material to generate a 3D object.
  • the method may further comprise evaluating a melt temperature for the build material (T evai ) by depositing the build material, fusing the deposited build material by applying energy, and measuring an increase in the temperature of the build material using the at least one thermal detector to evaluate the melt temperature for the build material (T evai ); and subsequently comparing the evaluated melt temperature for the build material (T evai ) to the previously determined differential scanning calorimetry melt temperature for a build material (T Dsc-meit) to obtain a known temperature variation for the at least one thermal detector (Tvar).
  • This feature may be included in the method after a previously determined DSC melt temperature for a build material (TDsc-meit) has been obtained but prior to determining an operational melt temperature (Top-meit). This feature enables the use of an up-to-date temperature variation for the at least one thermal detector (Tvar), which can be useful if the temperature variation of a thermal detector changes over time.
  • the method may be adapted for use with multiple build materials within a single build material container or multiple build materials within multiple build material containers.
  • An apparatus for generating a 3D object may comprise at least one thermal detector, which may be used to monitor the temperature of the build material during melting.
  • the apparatus may also comprise a processing unit to obtain a previously determined DSC melt temperature (T D sc-meit) from a storage medium on a build material container; calculate an operational melt temperature (Top-meit) using the previously determined DSC melt temperature (TDsc-meit) for a build material and a known temperature variation of at least one thermal detector (Tvar); and adjust the operation of the apparatus to use the calculated operational melt temperature (T 0p -meit).
  • the apparatus may further comprise an interface circuit to connect to an interconnect circuit on the build material container.
  • the interface circuit enables the apparatus to obtain the previously determined DSC melt temperature from the storage medium on the build material container.
  • a non-transitory machine-readable storage medium for use in generating a 3D object may be encoded with instructions executable by a processor, the machine-readable storage medium comprises instructions to calculate an operational melt temperature (Top-meit) using a previously determined DSC melt temperature from a build material container and a known temperature variation of at least one thermal detector (Tvar); and adjust the operation of the apparatus to use the calculated operational melt temperature (Top-meit).
  • Topic-meit an operational melt temperature
  • Tvar thermal detector

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  • Manufacturing & Machinery (AREA)
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Abstract

A method of optimising an apparatus for generating a three-dimensional (3D) object is described in which a previously determined differential scanning calorimetry (DSC) melt temperature for a build material (TDSC-melt) is obtained from a storage medium on a build material container; an operational melt temperature (TOp-melt) is determined using the previously determined DSC melt temperature for the build material (TDSC-melt) and a known temperature variation of the at least one thermal detector (TVar); and the operation of the apparatus is regulated by using the calculated operational melt temperature (TOp-melt).

Description

MELT TEMPERATURE DETERMINATION FOR 3D OBJECT GENERATION
BACKGROUND
[0001] Three-dimensional (3D) objects may be generated by depositing and melting successive layers of a build material; a layer of build material is deposited and then melted before another layer is deposited and melted such that it fuses to the previous layer. This continues layer-by-layer until a complete 3D object has been generated. The quality of 3D objects generated using such methods may vary widely depending on the nature of the build material and the temperature at which it is melted during printing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0002] Figure 1 is an example Differential Scanning Calorimetry (DSC) curve for a build material with a narrow melt temperature range and a sharp melting point.
[0003] Figure 2 is an example DSC curve for a build material with a wide melt temperature range that does not have a sharp melting point.
[0004] Figure 3 is an example plot of temperature increase over time that may be used to determine melt temperature.
[0005] Figure 4 is a schematic representation of a method for optimising an apparatus for generating a 3D object, wherein the apparatus comprises at least one thermal detector and a processing unit, according to an example.
[0006] Figure 5 is an example of a method for optimising an apparatus for generating a 3D object. DETAILED DESCRIPTION
[0007] A given build material will have a predicted melt temperature, but the exact melt temperature may vary from batch to batch of build material. In addition, some build materials have a narrow melt temperature range and a sharp melting point (see Figure 1 ), whilst others do not (see Figure 2). Melt temperature is a key parameter when printing 3D objects and using an inaccurate melt temperature when processing layers of a build material to generate 3D objects can lead to poor quality products, introduce high variability among different print jobs or even result in print job failure. Therefore, relying on a predicted melt temperature may not be not sufficient to ensure the generation of a good quality product, especially when the build material being used has a wide melt temperature range.
[0008] The melt temperature of a batch of build material may be determined by fusing a small area of build material whilst using a thermal camera to measure temperature increase over time (see Figure 3), and using the plot of temperature increase over time to determine the melt temperature. However, this process is time consuming, uses build material that could otherwise be used to generate a 3D object, relies on thermal cameras that may themselves be inaccurate, and is not suited for use with build materials that have a wide melt temperature range.
[0009] An accurate technique for measuring melt temperature is Differential Scanning Calorimetry, known as DSC, in which the amount of heat needed to increase the temperature of a sample is compared to the amount of heat needed to increase the temperature of a reference material. Melting is an endothermic process in which the material being melted absorbs heat as it undergoes a phase transition from solid to liquid. Therefore, using DSC to measure melt temperature results in melt curves such as the ones in Figures 1 and 2. The DSC curve of a batch of build material may be generated during the quality control testing carried out at the end of the manufacturing process used to prepare a batch of build material. [0010] A method of optimising an apparatus for generating a 3D object may comprise obtaining a previously determined DSC melt temperature for a build material (TDsc-meit). The previously determined DSC melt temperature for a build material (TDsc-meit) may be obtained from a storage medium on a build material container, obtained from a network, obtained from user input, or obtained in another secure manner. The previously determined DSC melt temperature (T Dsc-meit) may be derived from the DSC curve generated at the end of the manufacturing process used to prepare a batch of build material. The previously determined DSC melt temperature (TDsc-meit) can be stored on a storage medium on the build material container when the build material is loaded into the container. The storage medium on a build material container may, in one example, be a memory on a build material container. An operational melt temperature (Top-meit) may be calculated using the previously determined DSC melt temperature for the build material (TDsc-meit) and a known temperature variation of at least one thermal detector (Tvar), wherein“temperature variation” refers to the temperature difference between the detected temperature and the actual temperature arising from inaccuracies in the at least one thermal detector. For example, a temperature variation of +3 °C means that a thermal detector is detecting a temperature that is 3 °C higher than the actual temperature. Suitable thermal detectors for use in apparatuses for generating 3D objects include thermal cameras. As indicated above, thermal detectors may be inaccurate, for example the temperature variation readings obtained from the thermal cameras commonly used in apparatuses for generating 3D objects can have a magnitude of 2 °C or more. The known temperature variation of the at least one thermal detector (Tvar) may be based on the temperature variation of the at least one thermal detector as tested during assembly of thermal detectors. Such testing may be carried out using thermal patches. The operation of the apparatus may be adjusted to use the calculated operational melt temperature (Top-meit) so that the apparatus can accurately melt layers of the build material and thereby generate a satisfactory 3D object. An example of such a method is shown in Figure 5. [001 1 ] In combination, this method allows the optimisation of an apparatus on the basis of the batch of build material being melted and on the basis of the at least one thermal detector being used by the apparatus since the calculated operational melt temperature (Top-meit) is derived from both the previously determined DSC melt temperature for the build material (TDsc-meit) and the known temperature variation of the at least one thermal detector (Tvar). This enables the production of high quality 3D objects and results in less variability in the quality of 3D objects between print jobs. In turn, reduced variability between print jobs should result in fewer re-prints being required, enabling an increase in efficiency and a reduction in waste. In addition, since this method does not rely on the melting of a small disc of build material to determine the melt temperature at the start of a job, printable area can be increased and printing time can be reduced. All of this results in a lower total cost of ownership (TCO). This method of optimising an apparatus for generating a 3D object may be a computer- implemented method.
[0012] Figure 4 is a schematic representation of a method for optimising an apparatus for generating a 3D object in which“batch 1”,“batch 2” and“batch 3” of a build material are manufactured and their DSC curves calculated to result in previously determined DSC melt temperatures for each batch (TDsc-mem ), (TDSC- meit2) and (T Dsc-meit3). The known temperature variations of the at least one thermal detectors in Apparatus A and Apparatus B (TvarA and TvarB) are then used with the previously determined DSC melt temperatures for each batch (TDsc-mem ), (T Dsc-meit2) and (Tosc-meits) to calculate the operational melt temperatures for each batch when used in each printer (T0p-meitiA), (T0p-meit2A), (T0p-meit3A), (T0p-meiti B), (T0p-meit2B) and (T0p-meit3B). The apparatuses may be printers.
[0013] One means for calculating an operational melt temperature (Top-meit) may comprise adding the previously determined DSC melt temperature for the build material (TDsc-meit) and the known temperature variation of the at least one thermal detector (Tvar) to obtain the operational melt temperature (Top-meit): (TDSC-melt) + (Tvar) — (Top-melt)·
For example, a previously determined DSC melt temperature for a build material (T Dsc-meit) of 78 °C and a known temperature variation of a thermal detector (Tvar) of +3 °C will result in an operational melt temperature (Top-meit) of 81 °C. Thus, if a build material is heated to a temperature that the thermal detector reads as 81 °C, the build material will actually reach a temperature of 78 °C, which should enable the optimal melting of a batch of build material with a previously determined DSC melt temperature (TDsc-meit) of 78 °C. In an alternative example, a previously determined DSC melt temperature for a build material (TDsc-meit) of 155 °C and a known temperature variation of a thermal detector (Tvar) of -2 °C will result in an operational melt temperature (Top-meit) of 153 °C. Thus, if a build material is heated to a temperature that the thermal detector reads as 153 °C, the build material will actually reach a temperature of 155 °C, which should enable the optimal melting of a batch of build material with a previously determined DSC melt temperature (TDsc-meit) of 155 °C.
[0014] Another means for calculating an operational melt temperature (T0 -meit) may comprise subtracting the previously determined DSC melt temperature for the build material (TDsc-meit) from a predicted melt temperature for the build material (Tmeit) to obtain a first temperature difference (TDsc-ditf); subtracting the first temperature difference (TDsc-ditf) from the known temperature variation of the at least one thermal detector (Tvar) to obtain a second temperature difference (T var-diff); then adding the second temperature difference (Tvar-dm) to the predicted melt temperature for the build material (Tmeit) to obtain the operational melt temperature (T0p-meit):
T melt - T DSC-melt = T DSC-diff Tvar - T DSC-diff = T Var-diff T Var-diff + T melt = T Op-melt-
If the previously determined DSC melt temperature for the build material (T Dsc-meit) is lowerthan the predicted melt temperature for the build material (Tmeit) the first temperature difference (Tosc-dm) will be positive and vice versa. Furthermore, if the known temperature variation of the at least one thermal detector (Tvar) is greater than the first temperature difference (Tosc-ditt), the operational melt temperature (Top-meit) will be greater than the predicted melt temperature for the build material (Tmeit) and vice versa.
[0015] Using the first example given above, a previously determined DSC melt temperature (Tosc-meit) of 78° C for a build material with a predicted melt temperature (Tmeit) of 80° C will result in a first temperature difference (TDsc-dift) of +2° C; and a known temperature variation of a thermal detector (Tvar) of +3° C will result in a second temperature difference (Tvar-dift) of +1 ° C, which when added to the predicted melt temperature (Tmeit) of 80° C results in an operational melt temperature (Top-meit) of 81 ° C. Using the alternative example given above, a previously determined DSC melt temperature (Tosc-meit) of 155° C for a build material with a predicted melt temperature (Tmeit) of 150° C will result in a first temperature difference (Tosc-ditt) of -5° C; and a known temperature variation of a thermal detector (Tvar) of -2 °C will result in a second temperature difference (Tvar- diff) of +3 °C, which when added to the predicted melt temperature (Tmeit) of 150° C results in an operational melt temperature (Top-meit) of 153° C.
[0016] Another related means for calculating an operational melt temperature (T op-meit) may be adjusted such that it comprises subtracting a predicted melt temperature for the build material (Tmeit) from the previously determined DSC melt temperature for the build material (Tosc-meit) to obtain a first temperature difference (Tosc-ditt); adding the first temperature difference (Tosc-ditt) to the known temperature variation of the at least one thermal detector (Tvar) to obtain a second temperature difference (Tvar-diff); then adding the second temperature difference (T var-diff) to the predicted melt temperature for the build material (Tmeit) to obtain the operational melt temperature (Top-meit):
T DSC-melt - T melt = T DSC-diff T DSC-diff + Tvar = T Var-diff T Var-diff + T melt = T Op-melt- [0017] For build materials with a narrow melt temperature range and a sharp melting point (see Figure 1 ) the previously determined DSC melt temperature for the build material (TDsc-meit) may not vary significantly from the predicted melt temperature for the build material (Tmeit) and result in a relatively small first temperature difference (TDsc-cnff). However, using the predicted melt temperature for the build material (Tmeit) when generating a 3D object without optimisation might not be sufficient to ensure the generation of a good quality product due to variability in temperature readings by different thermal detectors (as described above). Hence, the second temperature difference (Tvar-dift) may be relatively large even if the first temperature difference (Tosc-diff) is relatively small.
[0018] All of the above means for calculating an operational melt temperature (T op-meit) will give the same result (for the same previously determined DSC melt temperature (TDsc-meit) and the same known temperature variation (Tvar)) and any other suitable means for calculating an operational melt temperature (Top-meit) will also give the same result.
[0019] Adjusting the operation of the apparatus to use the calculated operational melt temperature (Top-meit) may comprise instructing the apparatus to apply the calculated operational melt temperature (Top-meit) when melting the build material to generate a 3D object. Hence in the first example given above, the apparatus is instructed to apply a temperature of 81 ° C when melting the build material to generate a 3D object, and in the alternative example given above, the apparatus is instructed to apply a temperature of 153° C when melting the build material to generate a 3D object.
[0020] The method may further comprise evaluating a melt temperature for the build material (Tevai) by depositing the build material, fusing the deposited build material by applying energy, and measuring an increase in the temperature of the build material using the at least one thermal detector to evaluate the melt temperature for the build material (Tevai); and subsequently comparing the evaluated melt temperature for the build material (Tevai) to the previously determined differential scanning calorimetry melt temperature for a build material (T Dsc-meit) to obtain a known temperature variation for the at least one thermal detector (Tvar). This feature may be included in the method after a previously determined DSC melt temperature for a build material (TDsc-meit) has been obtained but prior to determining an operational melt temperature (Top-meit). This feature enables the use of an up-to-date temperature variation for the at least one thermal detector (Tvar), which can be useful if the temperature variation of a thermal detector changes over time.
[0021 ] The method may be adapted for use with multiple build materials within a single build material container or multiple build materials within multiple build material containers.
[0022] An apparatus for generating a 3D object may comprise at least one thermal detector, which may be used to monitor the temperature of the build material during melting. The apparatus may also comprise a processing unit to obtain a previously determined DSC melt temperature (TDsc-meit) from a storage medium on a build material container; calculate an operational melt temperature (Top-meit) using the previously determined DSC melt temperature (TDsc-meit) for a build material and a known temperature variation of at least one thermal detector (Tvar); and adjust the operation of the apparatus to use the calculated operational melt temperature (T0p-meit).
[0023] The apparatus may further comprise an interface circuit to connect to an interconnect circuit on the build material container. The interface circuit enables the apparatus to obtain the previously determined DSC melt temperature from the storage medium on the build material container.
[0024] A non-transitory machine-readable storage medium for use in generating a 3D object may be encoded with instructions executable by a processor, the machine-readable storage medium comprises instructions to calculate an operational melt temperature (Top-meit) using a previously determined DSC melt temperature from a build material container and a known temperature variation of at least one thermal detector (Tvar); and adjust the operation of the apparatus to use the calculated operational melt temperature (Top-meit).

Claims

1. A method of optimising an apparatus for generating a three-dimensional (3D) object, the method comprising:
- obtaining a previously determined differential scanning calorimetry (DSC) melt temperature for a build material (TDsc-meit) from a storage medium on a build material container;
- determining an operational melt temperature (Top-meit) using the previously determined DSC melt temperature for the build material (TDsc-meit) and a known temperature variation of at least one thermal detector (Tvar); and
- regulating the operation of the apparatus by using the calculated operational melt temperature (Top-meit).
2. The method of claim 1 , wherein the storage medium on a build material container is a memory on a build material container.
3. The method of claim 1 , wherein the at least one thermal detector is an at least one thermal camera.
4. The method of claim 1 , wherein determining an operational melt temperature (Top-meit) comprises:
- adding the previously determined DSC melt temperature for the build material (TDsc-meit) and the known temperature variation of the at least one thermal detector (Tvar) to obtain the operational melt temperature (T0p-meit)
(TDSC-melt) + (Tvar) = (Top-melt)·
5. The method of claim 1 , wherein determining an operational melt temperature (T0p-meit) comprises:
- subtracting the previously determined DSC melt temperature for the build material (TDsc-meit) from a predicted melt temperature for the build material (Tmeit) to obtain a first temperature difference (Tosc-dm) T melt - T DSC-melt - T diff!
- subtracting the first temperature difference (Tosc-ditt) from the known temperature variation of the at least one thermal detector (Tvar) to obtain a second temperature difference (Tvar-ditt)
Tvar - T DSC-diff = Tvar-dift;
and
- adding the second temperature difference (Tvar-dift) to the predicted melt temperature for the build material (Tmeit) to obtain the operational melt temperature (Top-meit)
Tvar-diff + Tmeit = Top-melt-
6. The method of claim 1 , wherein determining an operational melt temperature (Top-meit) comprises:
- subtracting a predicted melt temperature for the build material (Tmeit) from the previously determined DSC melt temperature for the build material (Tosc-meit) to obtain a first temperature difference (Tosc-ditt)
T DSC-melt - T melt - T diff!
- adding the first temperature difference (Tosc-ditt) from the known temperature variation of the at least one thermal detector (Tvar) to obtain a second temperature difference (Tvar-ditt)
T DSC-diff + Tvar = Tvar-dift;
and
- adding the second temperature difference (Tvar-ditt) to the predicted melt temperature for the build material (Tmeit) to obtain the operational melt temperature (Top-meit)
Tvar-dift + Tmeit = Top-melt-
7. The method of claim 1 , wherein, after obtaining a previously determined DSC melt temperature for a build material (TDsc-meit) but prior to determining an operational melt temperature (Top-meit), the method further comprises:
- evaluating a melt temperature for the build material (Tevai) by depositing the build material, fusing the deposited build material, and measuring an increase in the temperature of the build material using the at least one thermal detector to evaluate the melt temperature for the build material (Tevai); and
- comparing the evaluated melt temperature for the build material (Tevai) to the previously determined differential scanning calorimetry melt temperature for a build material (TDsc-meit) to obtain a known temperature variation for the at least one thermal detector (Tvar).
[0008] The melt temperature of a batch of build material may be determined by fusing a small area of build material whilst using a thermal camera to measure temperature increase over time (see Figure 3), and using the plot of
temperature increase over time to determine the melt temperature.
8. An apparatus for generating a 3D object, the apparatus comprising:
- at least one thermal detector; and
- a processing unit to:
acquire a previously determined DSC melt temperature for a build material (TDsc-meit) from a storage medium on a build material container; calculate an operational melt temperature (Top-meit) using the previously determined DSC melt temperature for the build material (TDSC- meit) and a known temperature variation of at least one thermal detector (Tvar); and
adjust the operation of the apparatus to use the calculated operational melt temperature (Top-meit).
9. The apparatus of claim 8, wherein the storage medium on a build material container is a memory on a build material container.
10. The apparatus of claim 8, wherein the at least one thermal detector is an at least one thermal camera.
1 1. The apparatus of claim 8, wherein the operational melt temperature (ToP- meit) is calculated by:
- adding the previously determined DSC melt temperature for the build material (TDsc-meit) and the known temperature variation of the at least one thermal detector (Tvar) to obtain the operational melt temperature (T0p-meit)
(TDSC-melt) + (Tvar) = (ToP-melt)·
12. The apparatus of claim 8, wherein the operational melt temperature (ToP- meit) is calculated by:
- subtracting the previously determined DSC melt temperature for the build material (TDsc-meit) from a predicted melt temperature for the build material (Tmeit) to obtain a first temperature difference (Tosc-ditt)
T melt - T DSC-melt - T diff!
- subtracting the first temperature difference (Tosc-ditt) from the known temperature variation of the at least one thermal detector (Tvar) to obtain a second temperature difference (Tvar-ditt)
Tvar - T DSC-diff = Tvar-dift;
and
- adding the second temperature difference (Tvar-ditt) to the predicted melt temperature for the build material (Tmeit) to obtain the operational melt temperature (ToP-meit)
Tvar-diff + Tmeit = ToP-melt·
13. The apparatus of claim 8, wherein determining an operational melt temperature (Top-meit) comprises:
- subtracting a predicted melt temperature for the build material (Tmeit) from the previously determined DSC melt temperature for the build material (TDsc-meit) to obtain a first temperature difference (Tosc-ditt)
T DSC-melt - T melt - T diff!
- adding the first temperature difference (Tosc-dm) from the known temperature variation of the at least one thermal detector (Tvar) to obtain a second temperature difference (Tvar-dm)
T DSC-diff + Tvar = Tvar-dift;
and
- adding the second temperature difference (Tvar-dift) to the predicted melt temperature for the build material (Tmeit) to obtain the operational melt temperature (Top-meit)
Tvar-diff + Tmeit = Top-melt-
14. The apparatus of claim 8 further comprising an interface circuit to connect to an interconnect circuit on the build material container, to enable the apparatus to obtain the previously determined DSC melt temperature (TDsc-meit) from the storage medium on the build material container.
15. A non-transitory machine-readable storage medium encoded with instructions executable by a processor, the machine-readable storage medium comprising instructions to:
- calculate an operational melt temperature (Top-meit) using a previously determined DSC melt temperature (TDsc-meit) from a build material container and a known temperature variation of at least one thermal detector (Tvar); and
- adjust the operation of the apparatus to use the calculated operational melt temperature (Top-meit).
PCT/US2019/025353 2019-04-02 2019-04-02 Melt temperature determination for 3d object generation Ceased WO2020204911A1 (en)

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