WO2016049621A1

WO2016049621A1 - System and method for laser based preheating in additive manufacturing environments

Info

Publication number: WO2016049621A1
Application number: PCT/US2015/052580
Authority: WO
Inventors: Sam Coeck; Piet VAN DEN ECKER
Original assignee: Materialise N.V.; Materialise Usa, Llc
Priority date: 2014-09-26
Filing date: 2015-09-28
Publication date: 2016-03-31

Abstract

A system and method for preheating building material using a laser scanning device in additive manufacturing environments is provided. Various embodiments involve the use of a control computer to determine a desired temperature distribution of the building material for a particular layer of the build process. The control computer further determines the current temperature distribution by means of a heat sensor and/or estimation based on a heat profile of the object being built. The control computer directs the laser scanning device to heat portions of the building material to achieve the desired temperature distribution by adjusting aspects of the laser scanning device for directing a laser beam to the portions of the building material.

Description

SYSTEM AND METHOD FOR LASER BASED PREHEATING IN ADDITIVE

MANUFACTURING ENVIRONMENTS

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] This application relates to the laser based preheating of building material in an additive manufacturing environment. More particularly, this application relates to a system and method for preheating a material, such as a powder bed cake, in a selective laser sintering apparatus by selectively applying a laser to the material based on certain parameters.

Description of the Related Technolo y

[0002] 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 from 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 and selective laser sintering ("LS") 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.

[0003] Typically, the laser beam from the laser scanning only provides a portion of the energy needed to polymerize or solidify layers of the building material. The remaining portion of the energy needed is provided by generally preheating the building material to a temperature near but under the melting point of the building material before the laser scanning is performed.

[0004] Existing techniques for preheating the building material are suboptimal. Properties of a 3D object created using LS, including density and strength of the 3D object, are based at least in part on the temperature of the building material prior to laser scanning. Existing preheating apparatuses, such as infrared (IR) heat lamps suspended above the building material, are not well suited to accurately heating all the various portions of the building material to an appropriate temperature to ensure the properties of the 3D object are of a high quality. In view of these and other problems identified by the inventors, a need for techniques for accurately preheating building material in an additive manufacturing environment are needed. SUMMARY

[0005] In one embodiment, a system for preheating building material using a laser scanning system in an additive manufacturing environment is provided. The system comprises a laser scanner configured to selectively direct a laser beam onto a surface of a building material. The system further comprises a computer control system comprising one or more computers having a memory and a processor. The computer control system is configured to determine a desired temperature distribution of the building material. The computer control system is further configured to determine a current temperature distribution of the building material. The computer control system is further configured to determine one or more portions of the surface of the building material to preheat based at least in part on the desired temperature distribution and the current temperature distribution. The computer control system is further configured to cause the laser scanner to direct the laser beam to the one or more portions.

[0006] In another embodiment, a method for preheating building material using a laser scanning system in an additive manufacturing environment is provided. The method comprises determining a desired temperature distribution of a building material. The method further comprises determining a current temperature distribution of the building material. The method further comprises determining one or more portions of the surface of the building material to preheat based at least in part on the desired temperature distribution and the current temperature distribution. The method further comprises directing a laser beam to the one or more portions.

[0007] In yet another embodiment, a non-transitory computer readable medium that when executed by a computer performs a method for preheating building material using a laser scanning system in an additive manufacturing environment is provided. The method comprises determining a desired temperature distribution of a building material. The method further comprises determining a current temperature distribution of the building material. The method further comprises determining one or more portions of the surface of the building material to preheat based at least in part on the desired temperature distribution and the current temperature distribution. The method further comprises directing a laser beam to the one or more portions. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is an example of a system for designing and manufacturing 3D objects.

[0009] Figure 2 illustrates a functional block diagram of one example of the computer shown in FIG. 1.

[0010] Figure 3 shows a high level process for manufacturing a 3D object using.

[0011] Figure 4A is an example of a laser scanning system which may be used to preheat a building material according to the systems and methods disclosed herein.

[0012] Figure 4B is an example of components of a laser scanning system of Figure 4B which may be used according to the systems and methods disclosed herein.

[0013] Figure 5 is a flowchart which illustrates one example of a process by which a laser scanning system may be used to preheat a building material.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

[0014] Systems and methods disclosed herein provide an accurate way to preheat building material using a laser in an additive manufacturing environment (e.g., a 3D printing application). Though some embodiments described herein are described with respect to selective laser sintering techniques using powder as a building material, the described system and methods may also be used with certain other additive manufacturing techniques that use different building materials as would be understood by one of skill in the art. The temperature distribution of the building material may be measured and/or estimated. For example, the temperature distribution of the building material may be measured using a heat sensor, such as an infrared camera. Additionally or alternatively, the temperature distribution of the building material may be estimated based on the known build process for a 3D object, which can be used to estimate the amount of energy that has been applied at any given time to different portions of the building material. Based on the measured and/or estimated temperature distribution, a laser can be selectively applied to certain portions of the building material to bring those certain portions to a desired temperature, and not applied to other portions of the building material. The energy level and/or duration that the laser is applied to the certain portions may be varied based on the temperature distribution and/or the known build process for the 3D object. Accordingly, the temperature distribution of the building material may be changed based on the laser applied to the certain portions such that the temperature distribution leads to a better build quality of the 3D object. [0015] Embodiments of the invention may be practiced within a system for designing and manufacturing 3D objects. Turning to Figure 1, an example of a computer environment suitable for the implementation of 3D object design and manufacturing is shown. The environment includes a system 100. The system 100 includes one or more computers 102a-102d, which can be, for example, any workstation, server, or other computing device capable of processing information. In some aspects, each of the computers 102a-102d can be connected, by any suitable communications technology (e.g., an internet protocol), to a network 105 (e.g., the Internet). Accordingly, the computers 102a- 102d 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 105.

[0016] The system 100 further includes one or more additive manufacturing devices (e.g., 3-D printers) 106a- 106b. As shown the additive manufacturing device 106a is directly connected to a computer 102d (and through computer 102d connected to computers 102a- 102c via the network 105) and additive manufacturing device 106b is connected to the computers 102a-102d via the network 105. Accordingly, one of skill in the art will understand that an additive manufacturing device 106 may be directly connected to a computer 102, connected to a computer 102 via a network 105, and/or connected to a computer 102 via another computer 102 and the network 105.

[0017] It should be noted that though the system 100 is described with respect to a network and one or more computers, the techniques described herein also apply to a single computer 102, which may be directly connected to an additive manufacturing device 106.

[0018] FIG. 2 illustrates a functional block diagram of one example of a computer of FIG. 1. The computer 102a includes a processor 210 in data communication with a memory 220, an input device 230, and an output device 240. In some embodiments, the processor is further in data communication with an optional network interface card 260. Although described separately, it is to be appreciated that functional blocks described with respect to the computer 102a need not be separate structural elements. For example, the processor 210 and memory 220 may be embodied in a single chip.

[0019] The processor 210 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.

[0020] The processor 210 can be coupled, via one or more buses, to read information from or write information to memory 220. The processor may additionally, or in the alternative, contain memory, such as processor registers. The memory 220 can include processor cache, including a multi-level hierarchical cache in which different levels have different capacities and access speeds. The memory 220 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.

[0021] The processor 210 also may be coupled to an input device 230 and an output device 240 for, respectively, receiving input from and providing output to a user of the computer 102a. 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.

[0022] The processor 210 further may be coupled to a network interface card 260. The network interface card 260 prepares data generated by the processor 210 for transmission via a network according to one or more data transmission protocols. The network interface card 260 also decodes data received via a network according to one or more data transmission protocols. The network interface card 260 can include a transmitter, receiver, or both. In other embodiments, the transmitter and receiver can be two separate components. The network interface card 260, 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.

[0023] FIG. 3 illustrates a process 300 for manufacturing a 3-D object or device. As shown, at a step 305, a digital representation of the object is designed using a computer, such as the computer 102a. For example, 2-D or 3-D data may be input to the computer 102a for aiding in designing the digital representation of the 3-D object. Continuing at a step 310, information is sent from the computer 102a to an additive manufacturing device, such as additive manufacturing device 106, and the device 106 commences the manufacturing process in accordance with the received information. At a step 315, the additive manufacturing device 106 continues manufacturing the 3-D object using suitable materials, such as a liquid resin.

[0024] 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 320, the 3-D object is generated.

[0025] FIG. 4A illustrates an exemplary additive manufacturing apparatus 400 for generating a three-dimensional (3-D) object. In this example, the additive manufacturing apparatus 400 is a laser sintering device. The laser sintering device 400 may be used to generate one or more 3D objects layer by layer. The laser sintering 400, for example, may utilize a powder, such as the powder surface 414, to build an object a layer at a time as part of a build process.

[0026] Successive powder layers are spread on top of each other using, for example, a leveling drum 422. After deposition, a computer-controlled C02 laser beam scans the surface and selectively binds together the powder particles of the corresponding cross section of the product. In some embodiments, the laser scanning device 412 is an X-Y moveable infrared laser source. As such, the laser source can be moved along an X axis and along a Y axis in order to direct its beam to a specific location of the top most layer of powder. Alternatively, in some embodiments, the laser scanning device 412 may comprise a laser scanner which receives a laser beam from a stationary laser source, and deflects it over moveable mirrors to direct the beam to a specified location in the working area of the device. During laser exposure, the powder temperature rises above the glass transition point after which adjacent particles flow together to create the 3D object. The device 400 may also optionally include a radiation heater (e.g., an infrared lamp) and/or atmosphere control device 416. The radiation heater may be used in addition to the laser preheating described herein to preheat the powder between the recoating of a new powder layer and the scanning of that layer. In some embodiments, the radiation heater may be omitted and the preheating may be performed only by the laser preheating described herein. The atmosphere control device may be used throughout the process to avoid undesired scenarios such as, for example, powder oxidation.

[0027] In some embodiments, the powder may be distributed using one or more moveable pistons 418(a) and 418(b) which push powder from a powder container 428(a) and 428(b) into a reservoir 426 which holds the formed object 424. The depth of the reservoir, in turn, is also controlled by a moveable piston 420, which increases the depth of the reservoir 426 via downward movement as additional powder is moved from the powder containers 428(a) and 428(b) in to the reservoir 426.

[0028] As discussed above, the powder may need to be preheated with the recoating of a new powder layer to achieve a particular temperature distribution of the powder, as the temperature distribution of the powder may not be in the desired state. For example, during the build process of an object, the surface temperature of the powder may be unevenly distributed over the surface area of the powder. This may occur for several reasons. For example, where a radiation heater is used to at least partially preheat the powder, the surface temperature may differ in different portions of the surface area of the powder. This can occur as the radiation heater is not able to apply heat in a uniform way to the powder. Additionally or alternatively, portions of the surface area of the powder may have a higher temperature than others at various times in the build process due to the proximity of those portions to areas of the powder that have been exposed to a laser beam directed to form the object as part of the build process. The energy from the laser beam used to raise the powder above the transition point (e.g., melting point) of the powder material also raises the temperature of the surrounding powder, with powder closer to the laser beam being heated more than the powder farther from the laser bean. Accordingly, the surface temperature of the powder may be unevenly distributed for one or more different reasons.

[0029] Accordingly, the additive manufacturing apparatus 400 may be configured to utilize the laser scanning device 412 (or a separate laser scanning device) to apply a laser beam to preheat certain portions of the surface area of the powder to achieve a desired temperature distribution of the surface area of the powder. It should be noted that where the laser beam is applied to preheat the powder but remain below the transition point of the powder material, the directing of the laser beam may be referred to using variations of the phrase "preheating the powder." Further, where the laser beam is applied to heat the powder above the transition point of the powder material, the directing of the laser beam may be referred to using variations of the phrase "building the object." The desired temperature distribution, in some embodiments, may be a substantially even temperature distribution over the entire surface area of the powder. For example, the desired temperature distribution may be to have the entire surface area of the powder be close to but under the transition point of the material of the powder (e.g., 10 degrees centigrade below the transition point). In some embodiments, the desired temperature distribution may be based on information about the object being built as part of the build process. For example, only portions of the surface area of the powder where an object is being built may be desired to have a temperature close to but under the transition point of the material of the powder. This may be desirable as preheating other portions of the powder where an object is not being built may unnecessarily use energy, and further may degrade the powder unnecessarily. The determination of the portions of the surface area of the powder to have at the desired temperature may be done based on the current layer of the object being built and include portions of the powder in the current layer that are to be built by directing the laser beam to those areas to raise the temperature of the powder above the transition point to form the object. In some embodiments, the preheating to achieve the desired temperature distribution is done on a layer by layer basis as the object is being built, where each layer is preheated by the laser scanning device 412. In some embodiments, the preheating of some layers may be skipped, for example, every other layer may be preheated by the laser scanning device 412. [0030] The determination of which areas of the surface area of the powder need to be preheated to achieve the desired temperature distribution may be determined in one or more ways. The determination may be made by a control computer 434 that is connected to the laser scanning device 412 as shown in FIG 4B. The control computer 434 may be the computer 102(a) from Figure 2 or the computer 305 from Figure 3. Alternatively, the control computer 434 may be a separate computer that is designed to drive the preheating process. The control computer 434 may also be configured to control the laser scanning device 412 to direct a laser beam as discussed herein. For example, the control computer 434 may further include software which controls the movement and functionality of the laser scanning device 412. As such, the control computer 434 may be configured to control the moment and activation of the laser scanning device.

[0031] In some embodiments, the control computer 434 may determine which areas of the surface area of the powder need to be preheated to achieve the desired temperature distribution based on information regarding the build process for the object being built in the additive manufacturing apparatus 400. For example, the control computer 434 may calculate a heat profile for the object being built that is used to determine which areas need to be preheated, for example on a per layer basis. The heat profile may include information as to what areas of the powder are to be built for each layer of the object. The heat profile may additionally or alternatively include information as to how the areas of the powder to be built for each layer affect the temperature distribution of the surface area of the powder at that layer and/or subsequent layers. For example, the heat profile may include the expected amount of energy that areas of the powder will absorb per layer based on directing of the laser beam to the powder to build the object and/or information as to how the directing of the laser beam will affect the temperature of those areas of the powder in that given layer and/or for subsequent layers.

[0032] Based on that heat profile information, the control computer 434 may determine or calculate which areas of the powder are below the desired temperature ("cold spots") per the desired temperature distribution and preheat those areas. In particular, the control computer 434 may estimate the current temperature distribution of the surface area of the powder based on the heat profile. The control computer 434 may use the estimate of the current temperature distribution to determine how and where to direct a laser beam to the surface area of the powder to achieve the desired temperature distribution as discussed above. [0033] Additionally or alternatively, in some embodiments, the additive manufacturing apparatus 400 also includes a heat sensor 436 such as an infrared camera. The heat sensor 436 may be utilized to determine (e.g., visualize/measure) the current temperature distribution of the surface area of the powder. The use of the heat sensor 436 may be used to more accurately determine the current temperature distribution. The heat sensor 436 may be connected to the control computer 434 and transfer data regarding the temperature distribution of the powder surface to the control computer 434. The control computer 434 may further process this data and utilize the information to determine the current temperature distribution of the surface area of the powder. The control computer 434 may use this current temperature distribution to determine how and where to direct a laser beam to the surface area of the powder to achieve the desired temperature distribution as discussed above.

[0034] The control computer 434 may be configured to control the laser scanning device 412 to direct a laser beam to the surface area of the powder by controlling one or more aspects, alone or in any combination, of laser scanning device 412 as discussed herein. In some embodiments, the laser scanning device 412 may include machine and optical controls that are controlled by the control computer 434 to control the one or more aspects. In particular, in one aspect, the control computer 434, controls the location that the laser scanning device 412 directs the laser beam on the surface area of the powder. Further, in another aspect, the control computer 434 may control the size of the laser beam (e.g., the surface area over which the laser beam is incident upon the surface area of the powder) output by the laser scanning device 412. In yet another aspect, the control computer 434 may control an energy level of the laser beam output by the laser scanning device 412. In a further aspect, the control computer 434 may control a speed and/or number of times ("scans") that a laser beam output by the laser scanning device 412 is moved over a particular portion of the surface area of the powder.

[0035] The various aspects of the laser scanning device 412 may be controlled by the control computer 434 in such a way as to ensure the proper/desired amount of energy is delivered to the appropriate areas of the surface area of the powder to achieve the desired temperature distribution. For example, the location that control computer 434 controls the laser scanning device 412 to direct the laser beam may be a location where the temperature of the surface area of the powder is lower than desired according to the desired temperature distribution. The control computer 434 may also control the laser scanning device 412 to avoid directing the laser beam to areas where the temperature of the surface area of the powder is at or above the desired temperature according to the desired temperature distribution.

[0036] In addition, the size of the laser beam that control computer 434 controls the laser scanning device 412 to use may be based on the amount of energy required at a particular portion of the surface area of the powder and/or area over which the surface area of the powder needs to be preheated. For example, a larger laser beam size may allow for the energy of the laser beam to be spread across a larger area, meaning that a given portion of the surface area receives a smaller amount of energy from the laser beam at a time. This larger beam size may be used to ensure that the amount of energy delivered to a particular portion of the surface area of the powder at a given time is reduced to ensure more homogenous preheating. Further, a larger laser beam size may preheat a larger surface area of the powder to heat the larger area more quickly. Conversely, a smaller size laser beam may allow for more energy to be directed to a given portion of the surface area of the powder to more quickly preheat the powder at that portion.

[0037] Further, the energy level of the laser beam that control computer 434 controls the laser scanning device 412 to use may be based on an amount of energy required at a particular portion of the surface area of the powder. For example, a higher energy laser beam may preheat a portion of the surface area of the powder to which the laser beam is directed to a greater amount at a time if the temperature of the powder at that portion is significantly below the desired temperature. Conversely, a lower energy laser beam may allow for less energy to be directed to a given portion of the surface area of the powder to more slowly preheat the powder at that portion. This may be used to ensure that the amount of energy delivered to a particular portion of the surface area of the powder at a given time is reduced to ensure more homogenous preheating.

[0038] In addition, the control computer 434 may control a speed and/or number of times ("scans") that a laser beam output by the laser scanning device 412 is moved over a particular portion of the surface area of the powder. For example, a portion of the surface area of the powder may be scanned more times and/or at a lower speed if the energy required to bring it to the desired temperature according to the desired temperature distribution is greater. Conversely, a portion of the surface area of the powder may be scanned less times and/or at a higher speed if the energy required to bring it to the desired temperature according to the desired temperature distribution is less. In some embodiments, more scans may be performed using a lower energy level of the laser beam to gradually add energy to the particular portions of the surface area of the powder to ensure more homogeneous. In some embodiments, it may be desired to utilize less scans and/or a faster scan speed to ensure more homogenous preheating.

[0039] Using the preheating system described above, a laser scanning device may be used to preheat material in an additive manufacturing process in a precise, inexpensive, and relatively simple fashion. Figure 5 is a flowchart which illustrates one example of a process by which a laser scanning device may be used to preheat material in an additive manufacturing process. The process begins at block 502, where the build process for a 3D object begins by coating (e.g., recoating or coating initially) the build area with a layer of the building material, such as a powder, using an additive manufacturing apparatus, such as additive manufacturing apparatus 400. Further, at an optional block 504, the building material is preheated using a radiant heater, such as radiant heater 416 controlled by a control computer, such as control computer 434, or another computer such as the computer 102a or 305. At the block 504, the building material may be preheated to such that no portion of the building material is above the transition point of the building material, however the temperature distribution may not be even as discussed above. For example, where the transition point is, for example 185 degrees C, the radiant heater may preheat the building material to approximately 160 degrees C, or where the transition point is a different temperature, the radiant heater may preheat the building material to approximately 20-25 degrees C below the transition point.

[0040] Continuing, at a block 506, a desired temperature distribution of the surface area of the powder for the current layer of the build process is determined by the control computer. As discussed above, the desired temperature distribution may be an even or homogenous distribution across the entire surface are of the powder, be based on the object to be built, or some other factors.

[0041] Further, at a block 508, the current temperature distribution of the surface area of the powder is determined using the control computer. As discussed above, the current temperature distribution may be determined using a heat sensor and/or estimated based on the build process for the object.

[0042] In addition, at a block 510, a control computer may determine or calculate which areas or portions of the powder are below the desired temperature ("cold spots") and the amount of energy required to bring those portions to the desired temperature based on the determined desired temperature distribution and the determined current temperature distribution. For example, the control computer may compute a difference between the determined desired temperature distribution and the determined current temperature distribution.

[0043] Also, at a block 512, the control computer may control a laser scanning device, such as the laser scanning device 412, to preheat the determined portions of the powder below the desired temperature by directing a laser beam and adjusting one or more aspects of the laser beam discussed above for each portion. It should be noted that since different portions of the powder may be at different temperatures before the laser beam is directed to those portions, the one or more aspects of the laser beam may be adjusted differently for different portions.

[0044] Continuing, at a block 514, the control computer may control the laser scanning device to direct the laser beam on the powder to build the current layer of the object. The control computer may control the position and one or more aspects of the laser beam to ensure the object is built by directing the laser beam to the appropriate areas/portions of the building material requiring building in a way that the building material is heated above the transition point in those areas/portions.

[0045] Further, at a block 516, the control computer or the other computer determines if the object is complete, or if there is at least one additional layer to be built. If the control computer or the other computer determines the object is complete, the process ends. If the control computer or other computer determines there is at least one additional layers to be built, the process returns to the block 502.

[0046] Various embodiments disclosed herein provide for the use of a 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.

[0047] 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.

[0048] 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.

Claims

WHAT IS CLAIMED IS:

1. A system for preheating building material using a laser scanning system in an additive manufacturing environment, comprising:

a laser scanner configured to selectively direct a laser beam onto a surface of a building material; and

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; determine a current temperature distribution of the building material;

determine one or more portions of the surface of the building material to preheat based at least in part on the desired temperature distribution and the current temperature distribution; and

cause the laser scanner to direct the laser beam to the one or more portions.

2. The system of claim 1, further comprising a heat sensor configured to measure temperature distribution of the building material, wherein the computer control system is further configured to determine the current temperature distribution based at least in part on the measured temperature distribution received from the heat sensor.

3. The system of claim 2, wherein the heat sensor comprises an infrared camera.

4. The system of claim 1, wherein the computer control system is further configured to determine the current temperature distribution based at least in part on a heat profile of an object to be built using the building material.

5. The system of claim 1, further comprising a radiant heater configured to preheat the building material to a first temperature below the desired temperature distribution.

6. The system of claim 5, wherein the computer control system is configured to determine the current temperature distribution after the radiant heater preheats the building material.

7. The system of claim 5, wherein the radiant heater comprises an infrared lamp.

8. The system of claim 1, wherein the computer control system is configured to adjust one or more aspects of the laser scanning device, the one or more aspects comprising one or more of the following: a size of the laser beam, a location of the laser beam, an energy level of the laser beam, a number of scans, and a scanning speed.

9. The system of claim 8, wherein the computer control system is configured to adjust the one or more aspects by directing changes in configuration of optics of the laser scanning device.

10. The system of claim 1, wherein the desired temperature distribution is an even temperature distribution over the surface of the building material.

11. The system of claim 1 , wherein the desired temperature distribution is based at least in part on portions of the building material corresponding to areas of an object to be built.

12. A method for preheating building material using a laser scanning system in an additive manufacturing environment, the method comprising:

determining a desired temperature distribution of a building material; and determining a current temperature distribution of the building material;

determining one or more portions of the surface of the building material to preheat based at least in part on the desired temperature distribution and the current temperature distribution; and

directing a laser beam to the one or more portions.

13. The method of claim 12, further comprising measuring the temperature distribution of the building material using a heat sensor, wherein determining the current temperature distribution is based at least in part on the measured temperature distribution.

14. The method of claim 13, wherein the heat sensor comprises an infrared camera.

15. The method of claim 12, wherein determining the current temperature distribution is based at least in part on a heat profile of an object to be built using the building material.

16. The method of claim 12, further comprising preheating the building material to a first temperature below the desired temperature distribution using a radiant heater.

17. The method of claim 16, wherein determining the current temperature distribution is performed after the radiant heater preheats the building material.

18. The method of claim 16, wherein the radiant heater comprises an infrared lamp.

19. The method of claim 12, further comprising adjusting one or more aspects of a laser scanning device configured to direct the laser beam, the one or more aspects comprising one or more of the following: a size of the laser beam, a location of the laser beam, an energy level of the laser beam, a number of scans, and a scanning speed.

20. The method of claim 19, wherein adjusting the one or more aspects is performed by directing changes in configuration of optics of the laser scanning device.

21. The method of claim 12, wherein the desired temperature distribution is an even temperature distribution over the surface of the building material.

22. The method of claim 12, wherein the desired temperature distribution is based at least in part on portions of the building material corresponding to areas of an object to be built.

23. A non-transitory computer readable medium that when executed by a computer performs a method for preheating building material using a laser scanning system in an additive manufacturing environment, the method comprising:

directing a laser beam to the one or more portions.