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Title:
SYSTEMS AND METHODS FOR THERMAL CYCLE CONTROL IN ADDITIVE MANUFACTURING ENVIRONMENTS
Document Type and Number:
WIPO Patent Application WO/2017/044833
Kind Code:
A1
Abstract:
Systems and methods for thermal cycle control in additive manufacturing environments is provided. Some embodiments described herein relate to the use of customized containers for holding build material and objects as they are manufactured during additive manufacture.

Inventors:
VAN DEN ECKER PIET (BE)
CRAEGHS TOM (BE)
Application Number:
PCT/US2016/051081
Publication Date:
March 16, 2017
Filing Date:
September 09, 2016
Export Citation:
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Assignee:
MAT NV (BE)
MAT USA LLC (US)
International Classes:
B29C67/00
Domestic Patent References:
WO2015108547A22015-07-23
Foreign References:
US6153142A2000-11-28
US20110252618A12011-10-20
Other References:
None
Attorney, Agent or Firm:
GARG, Ankur et al. (US)
Download PDF:
Claims:
WHAT IS CLAIMED IS:

1. A system for controlling the thermal cycle of building material in an additive manufacturing environment, comprising:

a temperature actuator configured to at least one of heat or cool the building material;

a temperature sensor configured to measure a temperature distribution of the building material;

a computer control system comprising one or more computers having a memory and a processor, the computer control system configured to:

determine a desired temperature distribution of the building material at one or more points in time over a time period;

measure a current temperature distribution of the building material during each of the one or more points in time over the time period using the temperature sensor;

cause the temperature actuator to at least one of heat or cool the building material based on a difference between the desired temperature distribution and the current temperature distribution at each of the one or more points in time during the time period.

2. The system of claim 1, further comprising a container having a size based on a size of an object to be manufactured, the container being configured to hold the building material.

3. The system of claim 2, wherein the temperature sensor is at least one of attached to, positioned above, positioned adjacent to, or positioned below the container.

4. The system of claim 2, wherein the temperature actuator is at least one of attached to, positioned within, positioned above, positioned below, or positioned on the side of the container.

5. The system of claim 2, further comprising a container processing apparatus configured to hold a plurality of containers including the container, wherein the temperature sensor and temperature actuator are attached to the container processing apparatus.

6. The system of claim 1, wherein the time period is a cooling period after an object is built using the building material.

7. The system of claim 1, wherein the time period is a heating period before an object is built using the building material.

8. The system of claim 1, wherein the time period is a build period during which an object is built using the building material.

9. The system of claim 1, wherein the desired temperature distribution of the building material is based on a feature of an object to be manufactured from the building material.

10. The system of claim 9, wherein the feature comprises one or more of a thickness of at least a portion of the object, a quality specification of the object, and a geometric feature of at least a portion of the object.

11. A method of controlling the thermal cycle of building material in an additive manufacturing environment, the method comprising:

determining a desired temperature distribution of the building material at one or more points in time over a time period;

measuring a current temperature distribution of the building material during each of the one or more points in time over the time period using the temperature sensor;

modifying the temperature of the building material in a first location based on a difference between the desired temperature distribution at the first location and the current temperature distribution at the first location at one of the one or more points in time during the time period; and modifying the temperature of the building material in a second location based on a difference between the desired temperature distribution at the first location and the current temperature distribution at the second location at one of the one or more points in time during the time period.

12. The method of claim 11, wherein the additive manufacturing environment comprises a container having a size based on a size of an object to be manufactured, and wherein the container is configured to hold the building material.

13. The method of claim 12, wherein the measuring of the current temperature distribution is performed by a temperature sensor, and wherein the temperature sensor is at least one of attached to, positioned above, positioned adjacent to, or positioned below the container.

14. The method of claim 13, wherein modifying the temperature in the first location is performed by a first temperature actuator, and wherein modifying the temperature in the second location is performed by a second temperature actuator, and wherein each of the first temperature actuator and the second temperature actuator is at least one of attached to, positioned within, positioned above, positioned below, or positioned on the side of the container.

15. The method of claim 14, wherein the additive manufacturing environment further includes a container processing apparatus, and wherein the method further comprises:

holding a plurality of containers in the container processing apparatus, wherein the plurality of containers includes the container, wherein the temperature sensor and temperature actuator are attached to the container processing apparatus.

16. The method of claim 11, wherein the time period is a cooling period after an object is built using the building material.

17. The method of claim 11, wherein the time period is a heating period before an object is built using the building material.

18. The method of claim 11, wherein the time period is a build period during which an object is built using the building material.

19. The method of claim 11, wherein the desired temperature distribution of the building material is based on a feature of an object to be manufactured from the building material.

20. The method of claim 19, wherein the feature comprises one or more of a thickness of at least a portion of the object, a quality specification of the object, and a geometric feature of at least a portion of the object.

Description:
SYSTEMS AND METHODS FOR THERMAL CYCLE CONTROL IN ADDITIVE

MANUFACTURING ENVIRONMENTS

CROSS REFERENCE(S) TO RELATED APPLICATION(S)

Field of the Invention

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 62/216,787, filed September 10, 2105, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] This application relates to the control of the thermal cycle of building material and objects in an additive manufacturing environment. More particularly, this application relates to systems and methods for controlling the thermal cycle through the use of individual build containers for different parts, temperature sensors, heating elements, and cooling elements.

Description of the Related Technology

[0003] Laser scanning systems are used in many different applications. One of these applications is the field of additive manufacturing, in which three dimensional solid objects are formed based on a digital model. Because the manufactured objects are three dimensional, additive manufacturing is commonly referred to as three dimensional ("3D") printing. The use of laser scanning systems in additive manufacturing is especially prevalent in stereolithography, selective laser sintering ("LS"), and laser melting manufacturing techniques. These techniques use laser scanning systems to direct a laser beam to a specified location in order to polymerize or solidify layers of build materials which are used to create the desired three dimensional ("3D") object.

[0004] In processes that produce plastic parts such as laser sintering, the laser beam from the laser scanning provides only a portion of the energy needed to polymerize or solidify layers of the building material. The remaining necessary energy is instead provided by preheating the building material to a temperature near, but under, the melting point of the building material prior to scanning. [0005] After the object is created, the object and the building material may need to cool down, such as by passively cooling. Once cooled below a certain temperature, the printed object is considered complete, although in some cases post-processing of the object may be necessary to finish the part (e.g., sand blasting to decrease surface roughness). Although existing additive manufacturing devices allow for cooling processes, they do not provide sufficient information about and temperature control over the entire additive manufacturing process. Accordingly, techniques for controlling the thermal cycles across the entire additive manufacturing process are needed.

SUMMARY

[0006] A system for controlling the thermal cycle of building material in an additive manufacturing environment. The system may include a temperature actuator configured to at least one of heat or cool the building material and a temperature sensor configured to measure a temperature distribution of the building material. The apparatus may further include a computer control system comprising one or more computers having a memory and a processor. The computer control system may be configured to determine a desired temperature distribution of the building material at one or more points in time over a time period and measure a current temperature distribution of the building material during each of the one or more points in time over the time period using the temperature sensor. The computer control system may further be configured to cause the temperature actuator to at least one of heat or cool the building material based on a difference between the desired temperature distribution and the current temperature distribution at each of the one or more points in time during the time period.

[0007] In another embodiment, a method of controlling the thermal cycle of building material in an additive manufacturing environment is provided. The method may include determining a desired temperature distribution of the building material at one or more points in time over a time period and measuring a current temperature distribution of the building material during each of the one or more points in time over the time period using the temperature sensor. The method may further include modifying the temperature of the building material in a first location based on a difference between the desired temperature distribution at the first location and the current temperature distribution at the first location at one of the one or more points in time during the time period. The temperature of the building material may also be modified in a second location based on a difference between the desired temperature distribution at the first location and the current temperature distribution at the second location at one of the one or more points in time during the time period.

BRIEF DESCRIPTION OF THE DRAWINGS

[0001] Figure 1 is an example of a customized container for manufacturing 3D objects.

[0002] Figure 1A is another example of a customized container for manufacturing 3D objects.

[0003] Figure 2 illustrates an example of an additive manufacturing system configured to utilize the customized containers described in Figures 1 and 1 A.

[0004] Figure 2A illustrates an example of a container processing apparatus of the additive manufacturing system of Figure 2.

[0005] Figure 2B illustrates another example of a container processing apparatus of the additive manufacturing system of Figure 2.

[0006] Figure 3 is a flowchart which illustrates one example of a process for determining placement of one or more temperature sensors and/or one or more temperature actuators.

[0007] Figure 4 is a flowchart which illustrates one example of a process for controlling the thermal cycle of build material and objects.

[0008] Figure 5 is graphical illustration of a thermal cycle of build material in a build process.

[0009] Figure 6 is an example of a system for designing and manufacturing 3D objects.

[0010] Figure 7 illustrates a functional block diagram of one example of the computer shown in FIG. 6.

[0011] Figure 8 shows a high level process for manufacturing a 3D object using an additive manufacturing system.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

[0012] The following description and the accompanying figures are directed to certain specific embodiments. The embodiments described in any particular context are not intended to limit this disclosure to the specified embodiment or to any particular usage. Those of skill in the art will recognize that the disclosed embodiments, aspects, and/or features are not limited to any particular embodiments.

[0013] Additive manufacturing processes generally include three phases: preheating, building, and cooling. The inventors have recognized that during these three phases, the various thermal cycles can impact significantly the quality of the object. For example, the thermal cycles can impact and lead to deformation of the object during the build process. The thermal cycles may also adversely affect the density and uniformity of the final object. In laser sintering applications, the cooling speed is a factor in the crystallinity of the material. Parts which are cooled faster have a lower degree of crystallinity. A lower degree of crystallinity can lead to a lower stiffness of the material in the final product.

[0014] The systems and methods disclosed herein provide the ability to control the thermal cycle throughout all three stages of the additive manufacturing process: preheating, build, and cooling. Thus, the thermal cycle is controllable both for the build material and also those objects formed from the build material during additive manufacture. Some embodiments described herein relate to the use of customized containers for holding build material and objects as they are manufactured during additive manufacture. These customized containers may have customized sizes. In some embodiments, the dimensions of the customized container may be based on the dimensions of the part to be built. For example, the dimensions of the container may be selected to minimize the amount of base material that will not be transformed into a solid material.

[0015] Other design criteria may be used to maximize the thermal control of the part. For example, in situations where there is less material surrounding the part, the temperature response in warm up or cool down of the part when heating or cooling from the sides will be faster. Further, some embodiments described herein relate to the use of temperature sensors and temperature actuators (e.g., heaters, coolers, etc.) to control the thermal cycle of build material and objects in the custom sized containers.

[0016] The systems and methods described herein may be performed using various additive manufacturing and/or three-dimensional (3D) printing systems and techniques. Typically, additive manufacturing techniques start from a digital representation of the 3D object to be formed. Generally, the digital representation is divided into a series of cross-sectional layers, or "slices," which are overlaid to form the object as a whole. The layers represent the 3D object, and may be generated using additive manufacturing modeling software executed by a computing device. For example, the software may include computer aided design and manufacturing (CAD/CAM) software. Information about the cross-sectional layers of the 3D object may be stored as cross-sectional data. An additive manufacturing (e.g., 3D printing) machine or system utilizes the cross-sectional data for the purpose of building the 3D object on a layer by layer basis. Accordingly, additive manufacturing allows for fabrication of 3D objects directly from computer generated data of the objects, such as computer aided design (CAD) files and in particular STL files. Additive manufacturing provides the ability to quickly manufacture both simple and complex parts without tooling and without the need for assembly of different parts.

[0017] Selective laser sintering (LS) is an additive manufacturing technique used for 3D printing objects. LS apparatuses often use a high-powered laser (e.g. a carbon dioxide laser) to "sinter" (i.e. fuse) small particles of plastic, metal, ceramic, glass powders, or other appropriate materials into a 3D object. The LS apparatus may use a laser to scan cross-sections on the surface of a powder bed in accordance with a CAD design. Also, the LS apparatus may lower a manufacturing platform by one layer thickness after a layer has been completed and add a new layer of material in order that a new layer can be formed. In some embodiments, an LS apparatus may preheat the powder in order to make it easier for the laser to raise the temperature during the sintering process. Though embodiments described herein may be described with respect to LS, the embodiments may also be used with other appropriate additive manufacturing techniques as would be understood by one of ordinary skill in the art.

[0018] The properties of the building material (e.g., polymers, metal, etc.) used for additive manufacturing and the dimensions of an object built from the building material may be affected by the thermal cycles the material experiences during manufacture. The quality of a manufactured object may be evaluated or measured based on certain material properties of the building material (e.g., mechanical properties). The quality of a manufactured object may also be evaluated based on the measured dimensional accuracy of the object as compared to the dimensions described in the object model. Accordingly, the quality of a manufactured object may be directly tied to the thermal cycles (e.g., cycles of heating and cooling over time, temperature curves experienced, etc.) experienced by the materials. The thermal cycle may be a historic temperature distribution of the object (e.g., the building material used to build the object) over time, such as a series of temperatures of the build material in different spatial sections of the build material at different points in time. Therefore, embodiments described herein may measure and control the thermal cycles experienced by the materials during additive manufacturing.

[0019] Traditional additive manufacturing equipment may be designed to use a single large build area, which has a fixed volume, for manufacture of any object or objects. The size of these build areas may be quite large, and therefore the amount of build material in the volume may also be quite large. Accordingly, there is a large thermal mass of material, so control of the thermal cycle of the build material and objects built may not be feasible in certain circumstances. For example, in a single large build area, it may be difficult to obtain an equal temperature distribution over the whole cooling period within a certain amount of time. Because of these challenges, parts built in a single large build area are often left to passively cool. But passive cooling has certain disadvantages. Among them is the fact that passive cooling is often a slow and time consuming process. Passive cooling also can result in inhomogeneous temperatures in the material throughout the build area. This inhomogeneity may frustrate attempts to determine (or control based on certain specifications) the thermal history of the build material and/or the manufactured object.

[0020] Accordingly, systems and methods described herein may utilize customized containers that act as the build area for objects to be manufactured. The containers may be sized so as to be approximately the same length, width, and height of the maximum dimensions of the object to be built. Because they are sized to fit the manufactured object, the customized containers may be much smaller than the single large build area used in conventional systems. The thermal mass of the building material in these customized smaller containers may be significantly less than the thermal mass of the building material present in a larger build area. As a result, the smaller container can be more homogeneously heated and/or cooled, and the thermal cycles accurately controlled. Using these types of customized smaller containers, it becomes feasible to ensure the building material closely tracks a desired thermal cycle throughout the build process of an object.

[0021] The desired thermal cycle for building material may be a set of desired temperature distributions of the building material at different time points. The temperature distribution of build material may be the set of temperatures of the building material at different spatial points in the container. [0022] In some embodiments, a desired thermal cycle for the build material may need to have a slow cooling process (e.g., the temperature of the building material at any point decreases at a certain rate). For example, where the building material comprises a polymer, a slow cooling process may lead to high degrees of crystallinity in the built object. The high degree of crystallinity may result in increased stiffness. Further, by ensuring all the build material for the object cools around the same rate, there may be fewer deformations due to the higher spatial homogeneity in the cooling process.

[0023] In some embodiments, the desired thermal cycle for the build material may be to keep the material at a relatively high temperature for a certain period of time, and then quickly cool the build material. In other embodiments, the desired thermal cycle may be to keep the building material at a certain temperature between room temperature and the melting point of the material to achieve maximal crystallization.

[0024] In some embodiments, the desired thermal cycle for the build material may be based on features (e.g., geometric features) of the object built from the build material. For example, the desired thermal cycle for portions of an object may be based on a thickness of the portions of the object. In one example, an object or portions of the object that are thicker (e.g., thicker walls) may be heated or cooled differently than an object or portions of the object that are thinner (e.g., thinner walls). For example, a thicker wall may be heated and cooled more quickly than a thin wall. There may be other examples of how thickness may be used to adjust heating and cooling.

[0025] In some embodiments, the desired thermal cycle may be based on other features of the object built from the build material, such as quality specification of the object to be built. For example, if an object has a quality specification of a prototype (e.g., quality specification is lower), then the cooling cycle of the desired thermal cycle may be different than if the object has a quality specification of an end-series object (e.g., finished product, quality specification is higher). In one example, an object with a quality specification of a prototype may be cooled more quickly than a product with a quality specification of an end-series object, for example, to build the object faster and/or at less cost for controlling the cooling process. There may be other examples of how quality specification may be used to adjust heating and cooling.

[0026] In addition, the use of customized containers may also provide other advantages to the additive manufacturing process. For example, the customized containers may be designed to be separate and removable from the additive manufacturing machine, so they can be preheated and cooled in a separate area, allowing for the additive manufacturing machine to continue being used, such as with a different customized container. This may allow for increased efficiency in use of the additive manufacturing device. Further, multiple customized containers may be capable of being placed on the additive manufacturing device at the same time, and therefore multiple objects may be built in multiple containers at the same time.

[0027] Figure 1 illustrates an example of a customized container 100. As shown, the customized container is sized as approximately the same size as the maximum dimensions of a part 105 (not shown in Figure 1, but shown in Figure 1A) to be built in the customized container 100. In some embodiments, customized containers 100 may be pre-designed in a number of different sizes so that an appropriate size container can be chosen for a particular part or object to be built.

[0028] The customized container 100 may be generally shaped as a rectangular box (or other appropriate geometric shape). The customized container 100 may include walls 110 and a build plate 115. In some embodiments, the build plate 115 may be moveable (e.g., removable) with respect to the walls 110. The customized container 100, in some embodiments, may further include a cover plate 120 that also may be removable. The build plate 115 may be moveable to allow for access to objects built in the container 100, for new build plates to be used with the remaining portion of the customized container 100, etc. The cover plate 120 may be removable to allow access to the interior of the customized container 100 as needed, but also to seal off the customized container 100 as needed.

[0029] In some embodiments, such as shown in Figure 1A, the customized container 100 may also include one or more temperature sensors 125 and/or one or more temperature actuators 130 attached to (e.g., integrated into the walls 110, or on the exterior of the walls 110 of the container 100) the customized container 100. These temperature sensors 125 and/or temperature actuators may be configured to sense temperature via direct physical contact or in a non-contact way. For example, the customized containers may use a radiant heater to actuate in combination with a thermal camera or pyrometer to measure temperature. Accordingly, the walls 110 of the customized container 100 may include electrical wiring. The wiring may be integrated into the walls 110, or on the exterior of the walls 110 of the container 100. The electrical wiring may connect to the one or more temperature sensors 125 and/or one or more temperature actuators 130. Further, the electrical wiring (or the temperature sensors 125 and/or one or more temperature actuators 130 directly) may connect to one or more connectors 140. The one or more connectors 140 may be configured to interface with a controller that controls the function of the temperature sensors 125 and/or the temperature actuators 130. For example, the one or more connectors 140 may be positioned on the container 100 such that when the container 100 is placed in an additive manufacturing device, the connectors 140 interface with complimentary connectors on the additive manufacturing device that interface with a controller. The controller may be attached or located in the containers 100, the additive manufacturing device, a container processing apparatus as described herein, or other suitable components of an additive manufacturing system.

[0030] In some embodiments, the container 100 may be equipped with a memory that stores information regarding the container. This information may include, for example, size information, properties of the container, or other container-related information. The stored information may be accessible via the connector 140 by a controller that may utilize the information to determine how to handle the particular container. For example, the controller may be configured to manage the preheating process in the container. It may also be configured to control various aspects of the build process, including for example, the preheating process in the container, the amount of building material to add or use, the cooling process, or some other aspect of the build process. In addition, the controller may be configured to control other functionality of the machine such as, for example, a robotic arm which may be used to grip and maneuver the container within the additive manufacturing device. In some embodiments, the memory may be part of an RFID (radio-frequency identification) tag, NFC (near field communication) tag, or some other type of device that can be read by a controller with the appropriate hardware.

[0031] Figure 2 illustrates an example of an additive manufacturing system configured to utilize the customized containers 100 described in Figures 1 and 1A. As shown, the system 200 includes at least an additive manufacturing device 210 configured to receive containers 100 (which are shown as the small rectangular-shaped objects in the system. The containers may be moved onto the additive manufacturing device 210 manually or automatically. For example, a robot 220 (e.g., moveable robotic arm) may be configured to place the containers 100 onto the additive manufacturing device 210 to build the object, and remove the containers 100 from the additive manufacturing device 210 after the object is built. Additionally or alternatively, the system 200 may have conveyor belts 230 that are configured to move containers as needed through the system 200.

[0032] The system 200 may also include a container processing apparatus 240. In some embodiments, the container processing apparatus 240 may be configured to preheat and/or cool the building material in the containers 100. In some embodiments, there may be container processing apparatuses 240 for preheating and cooling the building material. The robot 220 and/or conveyor belts 230 may be configured to facilitate the containers 100 being placed on and removed from the container processing apparatus 240.

[0033] In embodiments where the customized container 100 does not include temperature sensors 125 and/or temperature actuators 130, temperature sensors 125 and/or temperature actuators 130 may be included in the container processing apparatuses 240. Further, in some embodiments, irrespective of whether the customized container 100 includes temperature sensors 125 and/or temperature actuators 130, the container processing apparatuses 240 may include one or more complimentary connectors to interface with connectors 140 on the containers 100. The connectors on the container processing apparatuses 240 may interface with a controller. As discussed above, such an interface may be used to allow the controller to determine properties of the container to properly control the build of objects and thermal cycles and/or control temperature sensors 125 and/or temperature actuators 130 to manage the thermal cycle of the building material.

[0034] As shown in Figure 2A, in some embodiments, the container processing apparatuses 240 may have the shape of a shelving wall, having a number of slots 245 configured to receive containers 100. Accordingly, multiple containers 100 can be processed (e.g., thermal cycles monitored and controlled) by the container processing apparatuses 240 at a time.

[0035] Figure 2B illustrates another example of a container processing apparatus 240 of Figure 2. In this embodiment, the container processing apparatus 240 comprises a conveyor belt system 280. Further, as shown, the container processing apparatus 240 comprises one or more temperature sensors 125 and/or temperature actuators 130 placed alongside a conveyor belt 280. The temperature sensors 125 and/or temperature actuators 130 may be positioned so as to monitor and control the thermal cycle of containers 100 that move along the conveyor belt 280. [0036] As shown in system 200, the system 200 may comprise a first container processing apparatus 240 for receiving containers 100 and preheating the containers 100. The containers 100 may be preheated with the build material inside the containers 100. Additionally or alternatively, the system 200 may have a separate build material conditioning apparatus 290 that is configured to store/receive build material and preheat it according to the desired thermal cycle, and place the build material in the container 100 on a layer by layer basis during the build process of an object.

[0037] The container 100 may then be moved to the additive manufacturing apparatus 210, and the desired object built in the container 100. After the object is built, the container 100 may be moved to a second container processing apparatus 240 for receiving the containers 100 and cooling the containers 100 according to the desired thermal cycle.

[0038] The system 200 may further have a finalization apparatus 295, which removes the object from the container 100 and separates unused build material from the part (such as for reuse of the build material). In some embodiments, the unused build material may be placed back in another container 100 or in the build material conditioning apparatus 200.

[0039] Figure 3 illustrates an example of a process 300 for determining placement of one or more temperature sensors 125 and/or one or more temperature actuators 130 on the containers 100 and/or the container processing apparatus 240. The process begins at block 305, where an object to be built using additive manufacturing techniques is selected. The process then moves to block 310, where a container 100 is selected based on the size of the object to be built. Next, at block 315, a computer simulation of a build of the selected object using an additive manufacturing device and the selected container is performed. The simulation may be performed in various ways. In some embodiments, finite element analysis (FEA) or computational fluid dynamics analysis (CFD) may be used. These various analytical techniques may be performed by or assisted by computer software packages. For example, simulation software packages such as COMSOL® (http://www.comsol.com/comsol-multiphysics) or ANSYS may be used to simulate an entire thermal history for a build.

[0040] During the simulation, the projected thermal cycle (e.g., temperature distribution of building material) over time in the container is computed and stored. The projected thermal cycle may be simulated based on a simulated preheat period, a simulated build period, and/or a simulated passive cool down period. Based on the simulation, it may be determined where spatially in the container the temperature is too hot or too cold at a given time period. The determination may be based on a desired thermal cycle for the building material (e.g., desired temperature distribution over time). In some embodiments, the determination may be based on features (e.g., quality specification, geometrical features, thickness, etc.) of the object to be built. As discussed, such features may also be used to determine the desired thermal cycle. Based on these locations, the placement of temperature sensors 125 and/or temperature actuators 130 may be selected so as to be able to monitor and/or affect the temperature in these locations. Accordingly, at block 320, it may be determined, based on the temperature distribution calculated over time, the positon to place temperature sensors 125 and/or temperature actuators 130 in the container 100 or on the container processing apparatus 240.

[0041] Figure 4 illustrates an example of a process 400 for controlling the thermal cycle of build material and objects. The process begins at block 405, where the temperature distribution of building material in the container 100 may be measured using one or more temperature sensors 125 at a given time point. The process then moves to block 410, where the measured temperature distribution may be compared to a desired temperature distribution at the given time point. At decision block 415, it is determined if the measured temperature distribution of the building material differs from the desired temperature distribution (e.g., differs by a threshold temperature difference). If at decision block 415 it is determined the measured temperature distribution of the building material does not differ from the desired temperature distribution, the process continues to block 425. If at decision block 415 it is determined the measured temperature distribution of the building material does differ from the desired temperature distribution, the process continues to block 420.

[0042] At block 420, temperature actuators 130 are used to heat/cool the building material in the appropriate areas of the container to try and achieve the desired temperature distribution. For example, the amount of heating/cooling applied to a particular area of the container may be based on a temperature difference between a desired temperature and measured temperature of the build material in the area at that time. The process then continues to block 425.

[0043] At block 425, it is determined if the object has been built and cooled (e.g., based on time and/or temperature of the object as may be measured by temperature sensors 125). If at block 420 it is determined the object has not been built and cooled, the process returns to block 405, else the process ends.

[0044] Figure 5 is a graphical illustration of the measured thermal cycles that may be generated using the process described above in connection with Figure 4. In this particular example, a graph 500 is shown which provides measurements from a build volume on a plastic laser sintering device. The graph illustrates the cooling down of different points in the build over time. The x-axis 502 on the graph shows the time in hours. The y-axis 504 shows temperature. The temperature readings shown in the graph 500 may be measured with thermocouples attached to pins and/or probes inserted into the build material at various identified locations, and measured over time. The locations 506 are described in Figure 5 as their position within the container in three dimensions. In this particular example, the locations in the container are described according to the following key:

[0045] From bottom to top: B= bottom M = middle U = Upper

[0046] From front to back: F = Front C = center B = back

[0047] From left to right: 1-2-3-4

[0048] Thus, the point BC3 represents a point at the bottom, in the center (in between the front and the back) and in the center/right. As can be seen in the graph, there is a significant measured difference in the cooling period of the point BC3 (top curve 508) or the point UF3 (the bottom curve 510). Thus, based on these measurements, the temperature actuators 130 may be used to influence the temperature in the various locations so that they conform to a desired temperature at various measured times.

[0049] Embodiments of the invention may be practiced within a system for designing and manufacturing 3D objects. Turning to Figure 6, an example of a computer environment suitable for the implementation of 3D object design and manufacturing is shown. The environment includes a system 600. The system 600 includes one or more computers 602a-602d, which can be, for example, any workstation, server, or other computing device capable of processing information. In some aspects, each of the computers 602a-602d can be connected, by any suitable communications technology (e.g., an internet protocol), to a network 605 (e.g., the Internet). Accordingly, the computers 602a-602d may transmit and receive information (e.g., software, digital representations of 3-D objects, commands or instructions to operate an additive manufacturing device, etc.) between each other via the network 605. [0050] The system 600 further includes one or more additive manufacturing devices (e.g., 3-D printers) 606a-606b. As shown the additive manufacturing device 606a is directly connected to a computer 602d (and through computer 602d connected to computers 602a-602c via the network 605) and additive manufacturing device 606b is connected to the computers 602a-602d via the network 605. Accordingly, one of skill in the art will understand that an additive manufacturing device 606 may be directly connected to a computer 602, connected to a computer 602 via a network 605, and/or connected to a computer 602 via another computer 602 and the network 605.

[0051] It should be noted that though the system 600 is described with respect to a network and one or more computers, the techniques described herein also apply to a single computer 602, which may be directly connected to an additive manufacturing device 606. Any of the computers 602a-602d may be configured to function as the controller described with respect to FIGs. 1-4. Further, any of the computers 602a-602d may be configured to perform the processes described herein, including the processes 300 and 400 described with respect to FIGs. 3 and 4.

[0052] FIG. 7 illustrates a functional block diagram of one example of a computer of FIG. 1. The computer 502a includes a processor 710 in data communication with a memory 720, an input device 730, and an output device 740. In some embodiments, the processor is further in data communication with an optional network interface card 770. Although described separately, it is to be appreciated that functional blocks described with respect to the computer 502a need not be separate structural elements. For example, the processor 710 and memory 720 may be embodied in a single chip.

[0053] The processor 710 can be a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any suitable combination thereof designed to perform the functions described herein. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0054] The processor 710 can be coupled, via one or more buses, to read information from or write information to memory 720. The processor may additionally, or in the alternative, contain memory, such as processor registers. The memory 720 can include processor cache, including a multi-level hierarchical cache in which different levels have different capacities and access speeds. The memory 720 can also include random access memory (RAM), other volatile storage devices, or non-volatile storage devices. The storage can include hard drives, optical discs, such as compact discs (CDs) or digital video discs (DVDs), flash memory, floppy discs, magnetic tape, and Zip drives.

[0055] The processor 710 also may be coupled to an input device 730 and an output device 740 for, respectively, receiving input from and providing output to a user of the computer 602a. Suitable input devices include, but are not limited to, a keyboard, buttons, keys, switches, a pointing device, a mouse, a joystick, a remote control, an infrared detector, a bar code reader, a scanner, a video camera (possibly coupled with video processing software to, e.g., detect hand gestures or facial gestures), a motion detector, or a microphone (possibly coupled to audio processing software to, e.g., detect voice commands). Suitable output devices include, but are not limited to, visual output devices, including displays and printers, audio output devices, including speakers, headphones, earphones, and alarms, additive manufacturing devices, and haptic output devices.

[0056] The processor 710 further may be coupled to a network interface card 770. The network interface card 770 prepares data generated by the processor 710 for transmission via a network according to one or more data transmission protocols. The network interface card 770 also decodes data received via a network according to one or more data transmission protocols. The network interface card 770 can include a transmitter, receiver, or both. In other embodiments, the transmitter and receiver can be two separate components. The network interface card 770, can be embodied as a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any suitable combination thereof designed to perform the functions described herein.

[0057] FIG. 8 illustrates a process 800 for manufacturing a 3-D object or device. As shown, at a step 805, a digital representation of the object is designed using a computer, such as the computer 602a. For example, 2-D or 3-D data may be input to the computer 602a for aiding in designing the digital representation of the 3-D object. Continuing at a step 810, information is sent from the computer 602a to an additive manufacturing device, such as additive manufacturing device 606, and the device 606 commences the manufacturing process in accordance with the received information. At a step 815, the additive manufacturing device 606 continues manufacturing the 3-D object using suitable materials, such as a liquid resin. At a step 820, the object is finally built.

[0058] These suitable materials may include, but are not limited to a photopolymer resin, polyurethane, methyl methacrylate-acrylonitrile-butadiene-styrene copolymer, resorbable materials such as polymer-ceramic composites, etc. Examples of commercially available materials are: DSM Somos® series of materials 7100, 8100, 9100, 9420, 10100, 11100, 12110, 14120 and 15100 from DSM Somos; ABSplus-P430, ABSi, ABS-ESD7, ABS-M30, ABS-M30i, PC-ABS, PC ISO, PC, ULTEM 9085, PPSF and PPSU materials from Stratasys; Accura Plastic, DuraForm, CastForm, Laserform and VisiJet line of materials from 3-Systems; the PA line of materials, PrimeCast and PrimePart materials and Alumide and CarbonMide from EOS GmbH. The VisiJet line of materials from 3-Systems may include Visijet Flex, Visijet Tough, Visijet Clear, Visijet HiTemp, Visijet e-stone, Visijet Black, Visijet Jewel, Visijet FTI, etc. Examples of other materials may include Objet materials, such as Objet Fullcure, Objet Veroclear, Objet Digital Materials, Objet Duruswhite, Objet Tangoblack, Objet Tangoplus, Objet Tangoblackplus, etc. Another example of materials may include materials from the Renshape 5000 and 7800 series. Further, at a step 820, the 3-D object is generated.

[0059] Various embodiments disclosed herein provide for the use of a controller or computer control system. A skilled artisan will readily appreciate that these embodiments may be implemented using numerous different types of computing devices, including both general purpose and/or special purpose computing system environments or configurations. Examples of well-known computing systems, environments, and/or configurations that may be suitable for use in connection with the embodiments set forth above may include, but are not limited to, personal computers, server computers, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like. These devices may include stored instructions, which, when executed by a microprocessor in the computing device, cause the computer device to perform specified actions to carry out the instructions. As used herein, instructions refer to computer-implemented steps for processing information in the system. Instructions can be implemented in software, firmware or hardware and include any type of programmed step undertaken by components of the system.

[0060] A microprocessor may be any conventional general purpose single- or multi-chip microprocessor such as a Pentium® processor, a Pentium® Pro processor, a 8051 processor, a MIPS® processor, a Power PC® processor, or an Alpha® processor. In addition, the microprocessor may be any conventional special purpose microprocessor such as a digital signal processor or a graphics processor. The microprocessor typically has conventional address lines, conventional data lines, and one or more conventional control lines.

[0061] Aspects and embodiments of the inventions disclosed herein may be implemented as a method, apparatus or article of manufacture using standard programming or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term "article of manufacture" as used herein refers to code or logic implemented in hardware or non- transitory computer readable media such as optical storage devices, and volatile or non-volatile memory devices or transitory computer readable media such as signals, carrier waves, etc. Such hardware may include, but is not limited to, field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), complex programmable logic devices (CPLDs), programmable logic arrays (PLAs), microprocessors, or other similar processing devices.