Selective modification of build strategy parameter(s) for additive manufacturing

A computerized method, system, program product and additive manufacturing (AM) system are disclosed. Embodiments provide for modifying object code representative of an object to be physically generated layer by layer by a computerized AM system using the object code. The computerized method may include providing an interface to allow a user to manually: select a region within the object in the object code, the object code including a plurality of pre-assigned build strategy parameters for the object that control operation of the computerized AM system, and selectively modify a build strategy parameter in the selected region in the object code to change an operation of the computerized AM system from the plurality of pre-assigned build strategy parameters during building of the object by the computerized AM system.

This application is related to co-pending U.S. patent application Ser. Nos. 15/677,406 and 15/677,426 all filed concurrently.

BACKGROUND OF THE INVENTION

The disclosure relates generally to additive manufacturing, and more particularly, to a method of selectively modifying an additive manufacturing build strategy parameter for a region of an object.

The pace of change and improvement in the realms of power generation, aviation, and other fields has accompanied extensive research for manufacturing objects used in these fields. Conventional manufacture of objects, such as metallic, plastic or ceramic composite objects, generally includes milling or cutting away regions from a slab of material before treating and modifying the cut material to yield a part, which may have been simulated using computer models, e.g., in drafting software. Manufactured objects which may be formed from metal can include, e.g., airfoil objects for installation in a turbomachine such as an aircraft engine or power generation system.

Additive manufacturing (AM) includes a wide variety of processes of producing an object through the successive layering of material rather than the removal of material. Additive manufacturing can create complex geometries without the use of any sort of tools, molds or fixtures, and with little or no waste material. Instead of machining objects from solid billets of material, much of which is cut away and discarded, the only material used in additive manufacturing is what is required to shape the object.

Additive manufacturing techniques typically include taking a three-dimensional (3D) computer aided design (CAD) object file of the object to be formed, and electronically slicing the object into layers (e.g., 18-102 micrometers thick) to create a file with a two-dimensional image of each layer (including vectors, images or coordinates) that can be used to manufacture the object. The 3D CAD object file can be created in any known fashion, e.g., computer aided design (CAD) system, a 3D scanner, or digital photography and photogrammetry software. The 3D CAD object file may undergo any necessary repair to address errors (e.g., holes, etc.) therein, and may have any CAD format such as a Standard Tessellation Language (STL) file. The 3D CAD object file may then be processed by a preparation software system (sometimes referred to as a “slicer”) that interprets the 3D CAD object file and electronically slices it such that the object can be built by different types of additive manufacturing systems. The preparation software system may be part of the CAD system, part of the computerized AM system or separate from both. The preparation software system may output an object code file in any format capable of being used by the desired computerized AM system. For example, the object code file may be an STL file or an additive manufacturing file (AMF), the latter of which is an international standard that is an extensible markup-language (XML) based format designed to allow any CAD software to describe the shape and composition of any three-dimensional object to be fabricated on any AM printer. Depending on the type of additive manufacturing used, material layers are selectively dispensed, sintered, formed, deposited, etc., to create the object per the object code file.

One form of powder bed infusion (referred to herein as metal powder additive manufacturing) may include direct metal laser melting (DMLM) (also referred to as selective laser melting (SLM)). In metal powder additive manufacturing, metal powder layers are sequentially melted together to form the object. More specifically, fine metal powder layers are sequentially melted after being uniformly distributed using an applicator on a metal powder bed. Each applicator includes an applicator element in the form of a lip, brush, blade or roller made of metal, plastic, ceramic, carbon fibers or rubber that spreads the metal powder evenly over the build platform. The metal powder bed can be moved in a vertical axis. The process takes place in a processing chamber having a precisely controlled atmosphere. Once each layer is created, each two dimensional slice of the object geometry can be fused by selectively melting the metal powder. The melting may be performed by a high powered irradiation beam, such as a 100 Watt ytterbium laser, to fully weld (melt) the metal powder to form a solid metal. The irradiation beam moves in the X-Y direction, and has an intensity sufficient to fully weld (melt) the metal powder to form a solid metal. The metal powder bed may be lowered for each subsequent two dimensional layer, and the process repeats until the object is completely formed.

Some metal powder AM systems employ two or more irradiation devices, e.g., high powered lasers or electron beams, that work together to form an object. Using two or more irradiation devices may be advantageous to create larger objects faster, to allow use of larger build areas or computerized AM systems, and/or improve the accuracy of a build. Typically, for a multiple irradiation device computerized AM system, each two-dimensional image of each layer includes assignments for different irradiation devices to form different regions of the object. The irradiation device assignment can be provided by any of the AM file systems, i.e., the CAD system that creates the original layout of the object, a preparation software system, or the control system of the multiple irradiation device computerized AM system.

One challenge with current AM techniques is that build strategies that direct how an AM system will create a region of an object within each layer are not readily modifiable. For example, for a multiple irradiation device AM system, how two or more irradiation devices will create the region or interact to create the region is not easily modifiable. Build strategy parameters can take a variety of forms. One example build strategy parameter includes the location of a stitching region in an object in which two or more irradiation devices interact to build the object. Stitching regions can have an increased surface roughness or altered material properties that may not be desired to be located in sensitive areas in certain objects, e.g., within a hole that requires precise dimensions or a smooth bearing surface. Conventionally, the location of stitching regions is automatically determined by one of the aforementioned AM file systems. Consequently, prevention of a stitching region being located in a sensitive area within an object cannot be easily controlled. Any changes require labor intensive revision of the object code representative of the object. This challenge exists regardless of the category of additive manufacturing employed.

BRIEF DESCRIPTION OF THE INVENTION

A first aspect of the disclosure provides a computerized method for modifying object code representative of an object to be physically generated layer by layer by a computerized additive manufacturing (AM) system using the object code, the computerized method comprising: providing an interface to allow a user to manually: select a region within the object in the object code, the object code including a plurality of pre-assigned build strategy parameters for the object that control operation of the computerized AM system; and selectively modify a build strategy parameter in the selected region in the object code to change an operation of the computerized AM system from the plurality of pre-assigned build strategy parameters during building of the object by the computerized AM system.

A second aspect of the disclosure provides a system for modifying object code representative of an object to be physically generated layer by layer by a computerized additive manufacturing (AM) system using the object code, the system comprising: a computing device providing an interface to allow a user to manually: select a region within the object in the object code, the object code including a plurality of pre-assigned build strategy parameters for the object that control operation of the computerized AM system; and selectively modify a build strategy parameter in the selected region in the object code to change an operation of the computerized AM system from the plurality of pre-assigned build strategy parameters during building of the object by the computerized AM system.

A third aspect of the disclosure provides a computerized additive manufacturing (AM) system for physically generating an object layer by layer based on object code representative of the object, the object code including a plurality of pre-assigned build strategy parameters for the object that control operation of the computerized AM system, the computerized AM system comprising: an additive manufacturing printer; and an object code modifier providing an interface to, prior to manufacturing the object, allow a user to manually: select a region within the object in the object code; and selectively modify a build strategy parameter in the selected region in the object code to change an operation of the computerized AM system from the plurality of pre-assigned build strategy parameters during building of the object by the computerized AM system.

A fourth aspect of the disclosure includes a computer program comprising program code embodied in at least one computer-readable medium, which when executed, enables a computer system to implement a computerized method for modifying object code representative of an object to be physically generated layer by layer by a computerized additive manufacturing (AM) system using the object code, the computerized method comprising: providing an interface to allow a user to manually: select a region within the object in the object code, the object code including a plurality of pre-assigned build strategy parameters for the object that control operation of the computerized AM system; and selectively modify a build strategy parameter in the selected region in the object code to change an operation of the computerized AM system from the plurality of pre-assigned build strategy parameters during building of the object by the computerized AM system.

A fifth aspect of the disclosure provides a computerized method for modifying object code representative of an object to be physically generated layer by layer by a computerized additive manufacturing (AM) system using the object code, the computerized method comprising: providing an interface to allow a user to manually: select a region within the object in the object code, the object code including a plurality of pre-assigned build strategy parameters for the object that control operation of the computerized AM system; and selectively add a build strategy parameter in the selected region in the object code to change an operation of the computerized AM system from the plurality of pre-assigned build strategy parameters during building of the object by the computerized AM system.

DETAILED DESCRIPTION OF THE INVENTION

As indicated above, the disclosure provides various methods, systems and program products that allow for selectively modifying a build strategy parameter in a selected region in object code for an object. The object code is used by a computerized additive manufacturing (AM) system to build the object. The selective modification of the build strategy parameter changes an operation of the computerized AM system from a plurality of pre-assigned build strategy parameters during building of the object. In this fashion, individual build strategy parameters can be readily customized to address features of the object that are challenging to build. This process is manual, not automated, which allows a user to selectively modify build strategy parameters rather than relying on automated, pre-assigned build strategies. As will be described, the selectively modified build strategy parameter can include practically any aspect of how the computerized AM system will be used to build an object.

At the outset, several descriptive terms may be used regularly herein, and it should prove helpful to define these terms at the onset of this section. These terms and their definitions, unless stated otherwise, are as follows. As used herein, “build strategy” refers to a plan for a computerized AM system and how one or more printing devices thereof will be used to build an object. Each build strategy may include a number of build strategy parameters that direct how device(s) of a given additive manufacturing (AM) system will be controlled. Each “build strategy parameter” controls one or more aspect(s) of how a particular printing device operates. For purposes of description, the disclosure will be described relative to a direct metal laser melting (DMLM) AM technique using a multiple irradiation device computerized AM system. In this example, and as will be described in greater detail with regard toFIGS. 2-4, build strategy parameters may include but are not limited to: processing chamber temperature, pressure, etc.; irradiation beam width, speed, power; scan vector spacing, length and start/stop positions; irradiation device assignments; scan vector end gap spacing and positioning; and stitching region position, size and shape/path. As will be further described, the selected region upon which changes in a build strategy parameter can be applied can be user defined and can include, for example, an areal region (e.g., within each of at least one layer of the object or for particular scan vector(s), used to build the object) or a volume of the object (e.g., a number of layers). As used herein, “pre-assigned build strategy parameters” are those parameters generated as part of the conversion of a CAD or other format representation of the object into a format capable of use by an AM system to print the object; they may be automatically generated. To “modify” a build strategy parameter may include changing a pre-assigned build strategy parameter or adding a build strategy parameter.

FIG. 1shows a schematic block diagram of an additive manufacturing (AM) environment40including an illustrative computerized additive manufacturing system100(hereinafter ‘AM system100’) according to embodiments of the disclosure. As will be described herein, a region modifier90that implements the teachings of the disclosure can be located in a number of locations within AM environment40. As noted, additive manufacturing techniques typically include taking a three-dimensional (3D) computer aided design (CAD) object file of the object to be formed and preparing it for use by AM system100. CAD object file52can be created in any now known or later developed fashion by using, e.g., a CAD system50to create it, a 3D scanner (not shown) that creates a raw object file54, or digital photography and photogrammetry software that creates raw object file54. Raw object file54, for example, may undergo any necessary repair to address errors (e.g., holes, etc.) therein to arrive at CAD object file52. In any event, CAD object file52that provides the 3D representation of the object may be created (shown, for example, in CAD system52) and may have any CAD format such as a Standard Tessellation Language (STL) file.

CAD object file52may require further preparation for use by an AM printer122of AM system100. To this end, preparation software56for carrying out any necessary preparation of CAD object file52is illustrated. Preparation software56may be located at various locations in AM environment40. Preparation software56can carry out any functions necessary to prepare CAD object file52into object code124O that can be used by AM printer122of AM system100. (AM system100generally includes an additive manufacturing control system120(“control system”) and an AM printer122). For example, preparation software56may include a “slicer” that interprets CAD object file52and electronically slices it to create a file (object code124O) with a two-dimensional image of each layer (including vectors, images or coordinates) that can be used to manufacture the object. Object code124O, as will be described, may also include a variety of additional computer executable instructions, and may undergo additional revisions using, for example, region modifier90according to embodiments of the disclosure. Preparation software56may output object code124O in any format capable of being used by the desired AM system100. For example, the object code may be an STL file or an AMF file.

In some cases, CAD system50includes preparation software56capable of preparing CAD object file52into a format that can be used by AM printer122of AM system100. In one alternative, preparation software56may be provided by a separate additive manufacturing (AM) preparation system60, located between CAD system50and AM printer100. In another alternative, preparation software56is integrated into code124of control system120of AM system100—either as part of preparation software56or as part of control system120functioning. In any event, a build strategy for the object is created that includes a plurality of pre-assigned build strategy parameters92for use by AM printer122to build the object.

As illustrated inFIG. 1, a region modifier90capable of carrying out the teachings of the disclosure can be located at any location at which preparation software56may be located. In addition, when region modifier90is provided as part of AM system100, it may be implemented as part of control system120or at a machine code level within AM printer122. Further, region modifier90may be provided as a separate entity that interacts with AM system100(lower right ofFIG. 1).

For purposes of description, the teachings of the disclosures will be described relative to building object(s)102using a powder bed infusion technique in the form of DMLM, shown inFIGS. 2-4. Consequently, build strategy parameters that will be described for selective modification according to embodiments of the disclosure will be those associated with DMLM, some of which were noted previously. While the description will reference DMLM and its related build strategy parameters, it is understood that the general teachings of the disclosure are equally applicable to many other additive manufacturing techniques including but not limited to: other forms of metal powder additive manufacturing such as direct metal laser sintering (DMLS), selective laser sintering (SLS) or electron beam melting (EBM); binder jetting; polymer printing and vat photopolymerization. Each AM technique will likely have its own particular set of build strategy parameters.

FIG. 2shows a schematic block diagram of an illustrative computerized AM system100for generating an object(s)102using DMLM. (Region modifier90shown as separate entity only for brevity). Object(s)102may include one large object or multiple objects, e.g., two objects102A,102B as shown, of which only a single layer is shown. The example shown uses multiple irradiation devices, e.g., four 100 Watt ytterbium lasers110,112,114,116, but it is emphasized and will be readily recognized that the teachings of the disclosure are equally applicable to an AM system100using any number of irradiation devices, i.e., one or more. The teachings of the disclosures are also applicable to any irradiation device, e.g., an electron beam, laser, etc., and many other techniques of additive manufacture, e.g., binder dispenser, object material dispenser, curing laser, etc. Object(s)102are illustrated as circular elements; however, it is understood that the additive manufacturing process can be readily adapted to manufacture any shaped object, a large variety of objects and a large number of objects on a build platform118. Any number of object(s)102can be built, e.g., one or more.

As noted relative toFIG. 1, AM system100generally includes control system120and an AM printer122. As will be described, control system120executes object code124O to generate object(s)102using AM printer122. A region modifier90according to embodiments of the disclosure is shown as an independent system interacting with control system120, but it could be located in any location described relative toFIG. 1, e.g., as part of code124. As a separate system, region modifier90can be configured to be AM system agnostic. Control system120is shown implemented on computing device126as computer program code. To this extent, computing device126is shown including a memory130and/or storage system132, a processor unit (PU)134, an input/output (110) stitching region136, and a bus138. Further, computing device126is shown in communication with an external110device/resource140and storage system132. In general, processor unit (PU)134executes computer program code124that is stored in memory130and/or storage system132. While executing computer program code124, processor unit (PU)134can read and/or write data to/from memory130, storage system132, I/O device140and/or AM printer122. Bus138provides a communication link between each of the objects in computing device126, and I/O device140can comprise any device that enables a user to interact with computing device126(e.g., keyboard, pointing device, display, etc.). Computing device126is only representative of various possible combinations of hardware and software. For example, processor unit (PU)134may comprise a single processing unit, or be distributed across one or more processing units in one or more locations, e.g., on a client and server. Similarly, memory130and/or storage system132may reside at one or more physical locations. Memory130and/or storage system132can comprise any combination of various types of non-transitory computer readable storage medium including magnetic media, optical media, random access memory (RAM), read only memory (ROM), etc. Computing device126can comprise any type of computing device such as an industrial controller, a network server, a desktop computer, a laptop, a handheld device, etc.

It is recognized that each system in AM environment40inFIG. 1(e.g., CAD system50, AM preparation system60, AM system100, and separate region modifier90) may include their own computer environment similar to that just described for AM system100, and may communicate with other systems of AM environment40using any now known or later developed communication pathways. Any computing device used can comprise any general purpose computing article of manufacture capable of executing computer program code installed by a user (e.g., a personal computer, server, handheld device, etc.). In other embodiments, a computing device can comprise any specific purpose computing article of manufacture comprising hardware and/or computer program code for performing specific functions, any computing article of manufacture that comprises a combination of specific purpose and general purpose hardware/software, or the like. In each case, the program code and hardware can be created using standard programming and engineering techniques, respectively. The computing device(s) employed may take a variety of forms. For example, in one embodiment, the computing device may comprise two or more computing devices (e.g., a server cluster) that communicate over any type of wired and/or wireless communications link, such as a network, a shared memory, or the like, to perform the various process steps of the disclosure. When the communications link comprises a network, the network can comprise any combination of one or more types of networks (e.g., the Internet, a wide area network, a local area network, a virtual private network, etc.). Network adapters may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modem and Ethernet cards are just a few of the currently available types of network adapters. Regardless, communications between the computing devices may utilize any combination of various types of transmission techniques.

Continuing withFIG. 2, as noted, AM system100and, in particular control system120, executes program code124to generate object(s)102. Program code124can include, inter alia, a set of computer-executable instructions (herein referred to as ‘system code124S’) for operating AM printer122or other system parts, and a set of computer-executable instructions (herein referred to as ‘object code124O’) defining object(s)102to be physically generated by AM printer122. As described herein, additive manufacturing processes begin with a non-transitory computer readable storage medium (e.g., memory130, storage system132, etc.) storing program code124. System code124S for operating AM printer122may include any now known or later developed software code capable of operating AM printer122.

Object code124O defining object(s)102may include a precisely defined 3D model of an object. Object code124O also includes a build strategy including plurality of pre-assigned build strategy parameters92(FIG. 1), as will be described in greater detail herein. Object code124O can be generated from any of a large variety of well-known CAD systems50(FIG. 1) (such as AutoCAD®, TurboCAD®, DesignCAD 3D Max, etc.), or any AM preparation system60(FIG. 1). Further, certain AM systems100now provide control systems120capable of creating object code124O, e.g., from a CAD object file52(FIG. 1) or a raw object file54(FIG. 1). In any event, object code124O can include any now known or later developed file format. Furthermore, object code124O representative of object(s)102may be translated between different formats. For example, object code124O may include STL files or AMF files. Object code124O representative of object(s)102may also be converted into a set of data signals and transmitted, received as a set of data signals and converted to code, stored, etc., as necessary. Object code124O may also be an input to AM system100and may come from a part designer, an intellectual property (IP) provider, a design company, the operator or owner of AM system100, or from other devices. In any event, control system120executes system code124S and object code124O, dividing object(s)102into a series of thin slices that assemble using AM printer122in successive layers of material. Region modifier90may modify object code124O per embodiments of the disclosure prior to manufacture by AM printer122.

AM printer122may include a processing chamber142that is sealed to provide a controlled atmosphere for object(s)102printing, e.g., a set pressure and temperature for lasers, a vacuum for electron beam melting, or another atmosphere for other forms of additive manufacture. A build platform118, upon which object(s)102is/are built, is positioned within processing chamber142. For the metal powder AM process example used herein, a number of irradiation devices110,112,114,116are configured to melt layers of metal powder on build platform118to generate object(s)102. While four irradiation devices110,112,114,116will be described herein, it is emphasized that the teachings of the disclosure are applicable to a system employing any number of devices, e.g., 1, 2, 3, or 5 or more.

Build strategy parameters for DMLM may include but are not limited to: irradiation beam width, speed, power; scan vector spacing, length and start/stop positions; and where more than one irradiation device is employed: irradiation device assignments, scan vector end gap (melt pool) spacing and positioning, and stitching region position, size and shape/path. To further explain,FIG. 3andFIG. 4show two examples of scan vectors and fields for a multiple irradiation device AM system.FIG. 3shows a schematic perspective view of irradiation devices of AM system100using two irradiation devices110,112, e.g., lasers. During operation, the irradiation device(s) (dashed lines) are guided, e.g., by scanner mirrors for lasers or electromagnetic field/electric coils for electron beams, along scan vectors (paths), which are indicated by arrows on a top surface of illustrative object102. Internal scan vectors202melt inner regions204of object120that scan linearly across a layer, and a very thin border206is melted with one to three contour scan vectors208that only follow a desired outer edge of the layer. Build strategy parameters for the two irradiation device AM system used here can include, for example, irradiation beam width, speed, power, and scan vector202,208spacing, length and start/stop positions. (Beam width controls a width of the irradiation beam side-to-side.) These build strategy parameters are also applicable to single irradiation device AM systems. InFIG. 3, each laser110,112has its own field (1and2, respectively) upon which it can work. Each irradiation device110,112may work within only a small portion of its respective field at any given time. Each field and the scan vectors are assigned to one or the other device110,112with an interface210(within oval) where fields1,2of pair of devices110,112meet. Thus, build strategy parameters can further include, for example, irradiation device assignments. Where each scan vector202goes, a melt pool is created, and where each scan vector202stops, its melt pool stops. Thus, where two scan vectors, e.g.,202A,202B, stop adjacent one another, a scan vector end gap229exists in which it is expected the melt pools will merge to create a solid object from the metal powder. Scan vector202,208(hereinafter collectively referred to as “scan vector(s)202”) spacing and positioning can also constitute build strategy parameters. Further, as noted, an irradiation device assignment indicating which scan vector is made by which irradiation device is a build strategy parameter. Each irradiation device110,112is calibrated in any now known or later developed manner. Each irradiation device110,112has had its laser or electron beam's anticipated position relative to build platform118correlated with its actual position in order to provide an individual position correction (not shown) to ensure its individual accuracy. Interface210in body222of object120defines a first portion224and a second portion226of body222made by different irradiation devices110,112of multiple irradiation device AM system100during a single build. Here, fields1,2meet at a line, creating a planar interface228in object102.

FIG. 4shows a schematic plan view of irradiation devices of an AM system using four irradiation devices110,112,114,116, e.g., lasers, in which stitching regions are created. Here, each irradiation device110,112,114,116has a field1,2,3or4including a non-overlapping field region230,232,234,236, respectively, in which it can exclusively melt metal powder, and at least one overlapping field region or stitching region240,242,244,246in which two or more devices can melt metal powder. (Herein, boxed numbers of devices110,112,114,116indicate which device creates the shape illustrated thereabout). In this regard, each irradiation device110,112,114,116may generate an irradiation device beam (two shown,160,162, inFIG. 2), respectively, that fuses particles for each slice, as defined by object code124O. For example, inFIG. 2, irradiation device110is shown creating a layer of object102B using irradiation device160in one region, while irradiation device112is shown creating a layer of object102B using irradiation device162in another region. In addition to those build strategy parameters described relative toFIG. 3, stitching region position, size and shape/path may also constitute build strategy parameters. Again, each irradiation device110,112,114,116is calibrated in any now known or later developed manner. That is, each irradiation device110,112,114,116has had its laser or electron beam's anticipated position relative to build platform118correlated with its actual position in order to provide an individual position correction (not shown) to ensure its individual accuracy. In one embodiment, each of plurality irradiation devices110,112,114,116may create an irradiation device beam, e.g.,160,162(FIG. 2), having the same cross-sectional dimensions (e.g., shape and size in operation), power and scan speed; however, such build strategy parameters can be selectively modified according to embodiments of the disclosure. It is recognized that while four devices110,112,114,116have been illustrated to describe a stitching region for overlapping fields, any two devices may create overlapping fields.

Returning toFIG. 2, an applicator164may create a thin layer of raw material166spread out as the blank canvas from which each successive slice of the final object will be created. Applicator164may move under control of a linear transport system168. Linear transport system168may include any now known or later developed arrangement for moving applicator164. In one embodiment, linear transport system168may include a pair of opposing rails170,172extending on opposing sides of build platform118, and a linear actuator174such as an electric motor coupled to applicator164for moving it along rails170,172. Linear actuator174is controlled by control system120to move applicator164. Other forms of linear transport systems may also be employed. Applicator164can take a variety of forms. In one embodiment, applicator164may include a body176configured to move along opposing rails170,172, and an actuator element (not shown inFIG. 2) in the form of a tip, blade or brush configured to spread metal powder evenly over build platform118, i.e., build platform118or a previously formed layer of object(s)102, to create a layer of raw material. The actuator element may be coupled to body176using a holder (not shown) in any number of ways. The process may use different raw materials in the form of metal powder. Raw materials may be provided to applicator164in a number of ways. In one embodiment, shown inFIG. 2, a stock of raw material may be held in a raw material device178in the form of a chamber accessible by applicator164. In other arrangements, raw material may be delivered through applicator164, e.g., through body176in front of its applicator element and over build platform118. In any event, an overflow chamber179may be provided on a far side of applicator164to capture any overflow of raw material not layered on build platform118. InFIG. 2, only one applicator164is shown. In some embodiments, applicator164may be among a plurality of applicators in which applicator164is an active applicator and other replacement applicators (not shown) are stored for use with linear transport system168. Used applicators (not shown) may also be stored after they are no longer usable.

In one embodiment, object(s)102may be made of a metal which may include a pure metal or an alloy. In one example, the metal may include practically any non-reactive metal powder, i.e., non-explosive or non-conductive powder, such as but not limited to: a cobalt chromium molybdenum (CoCrMo) alloy, stainless steel, an austenite nickel-chromium based alloy such as a nickel-chromium-molybdenum-niobium alloy (NiCrMoNb) (e.g., Inconel 625 or Inconel 718), a nickel-chromium-iron-molybdenum alloy (NiCrFeMo) (e.g., Hastelloy® X available from Haynes International, Inc.), or a nickel-chromium-cobalt-molybdenum alloy (NiCrCoMo) (e.g., Haynes 282 available from Haynes International, Inc.), etc. In another example, the metal may include practically any metal such as but not limited to: tool steel (e.g., H13), titanium alloy (e.g., Ti6Al4V), stainless steel (e.g.,316L) cobalt-chrome alloy (e.g., CoCrMo), and aluminum alloy (e.g., AlSi10Mg). In another example, the metal may include practically any reactive metal such as but not limited to those known under their brand names: IN738LC, Rene 108, FSX 414, X-40, X-45, MAR-M509, MAR-M302 or Merl 72/Polymet 972.

The atmosphere within processing chamber142is controlled for the particular type of irradiation device being used. For example, for lasers, processing chamber142may be filled with an inert gas such as argon or nitrogen and controlled to minimize or eliminate oxygen. Here, control system120is configured to control a flow of an inert gas mixture180within processing chamber142from a source of inert gas182. In this case, control system120may control a pump184, and/or a flow valve system186for inert gas to control the content of gas mixture180. Flow valve system186may include one or more computer controllable valves, flow sensors, temperature sensors, pressure sensors, etc., capable of precisely controlling flow of the particular gas. Pump184may be provided with or without valve system186. Where pump184is omitted, inert gas may simply enter a conduit or manifold prior to introduction to processing chamber142. Source of inert gas182may take the form of any conventional source for the material contained therein, e.g. a tank, reservoir or other source. Any sensors (not shown) required to measure gas mixture180may be provided. Gas mixture180may be filtered using a filter188in a conventional manner. Alternatively, for electron beams, processing chamber142may be controlled to maintain a vacuum. Here, control system120may control a pump184to maintain the vacuum, and flow valve system186, source of inert gas182and/or filter188may be omitted. Any sensors (not shown) necessary to maintain the vacuum may be employed. Other appropriate atmospheres may be provided for other AM techniques, e.g., 3D printing.

A vertical adjustment system190may be provided to vertically adjust a position of various parts of AM printer122to accommodate the addition of each new layer, e.g., a build platform118may lower and/or chamber142and/or applicator164may rise after each layer. An extent to which vertical adjustment system190moves may also be a build strategy parameter. Vertical adjustment system190may include any now known or later developed linear actuators to provide such adjustment that are under the control of control system120.

In operation, build platform118with metal powder thereon is provided within processing chamber142, and control system120controls the atmosphere within processing chamber142. Any aspect of atmospheric control within processing chamber142may also constitute a build strategy parameter. Control system120also controls AM printer122, and in particular, applicator164(e.g., linear actuator174) and irradiation device(s)110,112,114,116to sequentially melt layers of metal powder on build platform118to generate object(s)102according to object code124O. As noted, various parts of AM printer122may vertically move via vertical adjustment system190to accommodate the addition of each new layer, e.g., a build platform118may lower and/or chamber142and/or applicator164may rise after each layer.

WhileFIGS. 2-4have been described herein to provide an understanding of build strategy parameters, e.g., relative to the DMLM additive manufacturing technique. It is emphasized that other additive manufacturing techniques may employ different build strategy parameters. For example, in binder jetting, a binder liquid flow rate may constitute a build strategy parameter, or in 3D polymer printing, a temperature of polymer may constitute a build strategy parameter.

With reference toFIGS. 2-4, the flow diagram ofFIG. 5, and non-limiting examples shown inFIGS. 6-14, a computerized method for modifying object code124O representative of object102to be physically generated layer by layer by computerized AM system100using the object code, will now be described. At the outset, object code124O includes plurality of pre-assigned build strategy parameters92for object102that control operation of computerized AM system100. That is, object code124O has undergone some level of preparation for additive manufacture in which a build strategy therefore has been created. For example, irradiation device assignments are made, irradiation device beam width, speed and power are assigned, and scan vector spacing, and start/stops are known. Typically, this process occurs with AM system100through use of some form of AM preparation system. This process may also include any now known or later developed computerized slicing technique of object102into layers for additive manufacture. That is, object code124O may include a layer by layer representation of object102, each layer to be sequentially, physically generated by AM system100.

In a first process S10inFIG. 5, region modifier90provides an interface250(FIGS. 6-7) to allow a user to manually select a region246(FIG. 7) within object102in object code124O. The providing of interface250by region modifier90, as noted herein, may occur at any of a number of locations such as but not limited to: at AM system100(FIGS. 1-2); at CAD system50(FIG. 1); or at AM preparation system60apart from AM system100. Interface250(FIGS. 6-7) may be provided in any manner I/O device140(FIG. 2) can accommodate. Further, region246may be selected using any now known or later developed manner of inputting a two-dimensional or three-dimensional geographic selection into a computing device, e.g., via I/O device140for computing device126(FIG. 2).FIGS. 6 and 7show one embodiment of a two-dimensional selection of region246, andFIG. 9shows one embodiment of a three-dimensional selection of region266.

InFIGS. 6 and 7, a portion of object102, e.g., a layer248(slice) or a portion thereof, can be illustrated in an interface250. Here, region modifier90may provide interface250in the form of a graphical user interface (GUI)252showing layer248of object102to a user to allow the user to select region246as a two-dimensional area of layer248in which build strategy parameters will be selectively modified. As shown inFIG. 6, where possible, GUI252may illustrate pre-assigned build strategy parameters92in any now known or later developed fashion, e.g., color, textual indicators, dimensional indicators, mapping marks, tables, dropdown menus, etc. For example, inFIG. 6, irradiation device110assignment for all of layer248is noted textually (boxed number), and a scan vector spacing (i.e., space between adjacent scan vectors) may be indicated with color, e.g., blue, or cross-hatching. Although not shown, GUI252may include a large variety of textual indications of practically any desired additional pre-assigned build strategy parameters92, e.g., via an interactive table or listing. In the GUI embodiment, region246can be selected using any now known or later developed manner in which a portion of an image can be selected in GUI252. In the example shown inFIG. 7, a square cropping box256is employed; however, any other size or shape selector may be employed. Further, a freehand cropping tool may be employed for more precision. In another embodiment, one or more ranges of coordinates may be numerically input to select region246. While region246has been shown as a square two-dimensional area inFIG. 7, region246can take on practically any form including but not limited to: a line, a dot or particular scan vector(s)202. While a singular region246has been described as selected, it is emphasized that process S10can be repeated as many times as modifications are desired, e.g., for a number of layers of object102, for a number of regions within a layer, for a number of scan vectors within a layer, etc. Where more than one region246is selected in more than one layer, collectively, the selected region may extend vertically within object102, e.g., where the same region of a number of adjacent layers is selected.

In process S12inFIG. 5, region modifier90provides interface260(FIG. 8) to allow a user to manually selectively modify a pre-assigned build strategy parameter in selected region246in object code124O to change an operation of computerized AM system100from plurality of pre-assigned build strategy parameters92during building of the object by the computerized AM system. Interface260may be the same as that provided to select region246, or may be a different interface entirely, e.g., a textual input, a table input. The modification can be of any build strategy parameter applicable to region246. In one example shown, plurality of pre-assigned build strategy parameters92may include at least one pre-assigned irradiation device assignment for each layer of object102(e.g.,110for layer248inFIG. 6), and the selective modification may include changing the at least one pre-assigned irradiation device assignment within region246. In the example shown inFIG. 8, some of internal scan vectors202of region246(FIG. 7) may be re-assigned to be built by irradiation device112(boxed number), rather than irradiation device110. The modification can be made in any now known or later developed fashion of changing parameters in a GUI, e.g., by input into an entry of a table of pre-assigned build strategy parameters92, by selecting a different indicator from a dropdown menu, by drag and drop techniques, etc.

Referring toFIGS. 9 and 10, an embodiment for selecting a three-dimensional region261of object102is illustrated. Here, region modifier90may provide GUI250(FIG. 9) showing a volume262(total or portion) of object102to a user to allow the user to select region266as a three-dimensional area of volume262in which pre-assigned build strategy parameters92will be selectively modified. As shown inFIG. 9, where possible, GUI250may illustrate pre-assigned build strategy parameters92in any now known or later developed fashion, e.g., color, textual indicators, dimensional indicators, mapping marks, tables, dropdown menus, etc. For example, inFIG. 9, irradiation device110assignment for the left half of volume262and irradiation device112assignment for the right half of volume262are noted textually (boxed numbers), and a stitching region264is illustrated with a dashed cube or lines. GUI252may include a large variety of textual indications of practically any desired additional pre-assigned build strategy parameters92, e.g., via an interactive table or listing. In the GUI embodiment, region261can be selected using any now known or later developed manner in which a three-dimensional portion of an image can be selected in GUI252. In the example shown inFIG. 9, an elongated cropping cube268is employed; however, any other size or shape cropping selector may be employed. Further, a freehand cropping tool may be employed for more precision. In another embodiment, one or more ranges of coordinates may be numerically input to define region261. While region261has been shown as an elongated cubical three-dimensional volume inFIG. 9, region261can take on practically any three-dimensional form including preset three-dimensional forms, e.g., a sphere, or a particular portion of object102, e.g., a shroud of an airfoil.

In process S12inFIG. 5, region modifier90provides interface270(FIG. 10) to allow a user to manually selectively modify a build strategy parameter in selected region261(FIG. 9) in object code124O to change an operation of computerized AM system100from plurality of pre-assigned build strategy parameters92during building of the object by the computerized AM system. The providing of interface270by region modifier90, as noted herein, may occur at any of a number of locations such as but not limited to: at AM system100(FIGS. 1-2); at CAD system50(FIG. 1); or at AM preparation system60apart from AM system100. Interface270may be the same as that provided to select region261, or may be a different interface entirely, e.g., a textual input, a table input. In the example shown inFIG. 10, a size and/or shape of stitching region264is modified to avoid opening(s)272in object102. The modification can be made in any now known or later developed fashion of changing parameters in a GUI, e.g., by input into an entry of a table of pre-assigned build strategy parameters92, by selecting a different indicator from a dropdown menu, by drag and drop techniques, by selecting and modifying visually renderable build strategy parameters (e.g., stitching region position), etc.

While singular regions246,261have been described as selected, it is emphasized that process S10can be repeated as many times as modifications are desired, e.g., for a number of regions of object102. For example, selected region246(FIG. 7) may include a plurality of regions, and the layer to which it is addressed may include a plurality of layers, and each region may include a selectively modified build strategy parameter.

In process S14inFIG. 5, object code124O is used to build object102with the selectively modified build strategy parameter using computerized AM system100. The build may proceed in any now known or later developed fashion appropriate for the type of additive manufacturing employed, but using the build strategy parameter(s) as selectively modified according to embodiments of the disclosure.

Referring toFIGS. 11-14, embodiments of some illustrative pre-assigned build strategy parameters92for multiple irradiation device AM systems and related build strategy modifications will now be described. As noted herein, AM system100may include at least two irradiation devices110,112,114,116(FIG. 2). Where two irradiation devices are employed, the selected region (246inFIG. 7 or 261inFIG. 9) may include a stitching region264(FIG. 9) to be created by the at least two irradiation devices, e.g.,110,112inFIG. 9. Here, build strategy parameter(s) control operation of the irradiation devices of the computerized AM system relative to the stitching region.

Referring toFIG. 11, a portion of a first layer284of object102is shown superimposed next to a portion of a second, adjacent layer286of object102to illustrate an example selective modification relative to a stitching region282. Here, a selected region280encompassing stitching region282may extend vertically across a plurality of layers of the object (e.g., like region261inFIG. 9). Selected region280includes stitching region282in which two irradiation devices110,112each may create object102. First layer284may represent, for example, odd numbered layers, and second layer286may represent even numbered layers (or vice versa) of object102.

With reference toFIG. 11along withFIGS. 9 and 10, various embodiments of the disclosure include selectively modifying a position of stitching region282in selected region280of one or more layers284,286of object102from plurality of pre-assigned build strategy parameters92(FIG. 2). For example, conventional pre-assigned build strategy parameters92(FIG. 2) typically indicate a stitching region should be built vertically upon itself in each layer of object102, like stitching region264inFIG. 9. The assignment of the position of a stitching region per conventional pre-assigned build strategy parameters92(FIG. 2) does not consider avoiding object102features in which stitching region existence is not ideal, e.g., openings272inFIG. 9. In one embodiment, shown inFIG. 11, the selective modification according to one embodiment of the disclosure may include assigning a first position288for stitching region282in first layer284of object102, and assigning a second, different position290for stitching region282in a second, different layer286of object102. In this manner, stitching region position switches in each layer and issues arising from stitching region282being built upon itself in the same area in each layer can be avoided. For example, while not necessary in all instances, inFIG. 11, first position288of stitching region282in first layer284does not overlap with second, different position290of stitching region282in second, different layer286. Here, first position288may be on a first lateral side of a centerline C of selected region280, and second, different position290may be on a second, different lateral side of centerline C of selected region280. In this manner, stitching region282position shifts from first position288to second, different position290as object102is built, creating a less rough surface at an outer surface of object102and perhaps creating a stronger object102due to the geographic distribution of stitching region282.

In another embodiment, the build strategy parameter selective modifying may include modifying a size of stitching region264in selected region261of layer(s) of object102from the plurality of pre-assigned build strategy parameters92(FIG. 2). This selective modification can be observed by comparing stitching region264inFIG. 9, having a width W1, to stitching region264inFIG. 10after modification having a different width W2(smaller in example shown).FIG. 10also shows another embodiment including modifying a shape (or path) of stitching region264in selected region261of layer(s) of object102from the plurality of pre-assigned build strategy parameters92(FIG. 2). InFIG. 10, stitching region264curves around openings272in object102, compared to extending linearly through openings272inFIG. 9.FIG. 10also shows another, simpler embodiment of modifying a position of stitching region264in selected region266of layer(s) of object102from plurality of pre-assigned build strategy parameters92(FIG. 2) compared toFIG. 11. That is, inFIG. 10, stitching region264is moved laterally in some spots to avoid openings272in object102, compared to extending through openings272inFIG. 9. The modifications shown can be made, for example, by drag and drop techniques, or textual inputs.

Referring toFIGS. 12 and 13, in another embodiment, build strategy parameter modifying may include modifying a characteristic of one or more scan vector end gaps302among a plurality of spaced scan vector end gaps300created by at least two irradiation devices, e.g.,110,112(FIG. 2). More particularly,FIGS. 12 and 13show scan vectors202A,202B each formed by at least two irradiation devices, e.g., scan vectors202A formed by one irradiation device (e.g.,110inFIG. 2), and scan vectors202B formed by another irradiation device (e.g.,112inFIG. 2). As shown best inFIG. 12, scan vectors202A,202B define a scan vector end gap300in a spaced between melt pool ends310,314of the scan vectors. That is, each scan vector end gap300is defined between a first melt pool end310of a first irradiation device (e.g.,110for scan vectors202A) in stitching region312(FIG. 13) and a second, abutting melt pool end314of a second, different irradiation device (e.g.,112for scan vectors202B) in stitching region312(FIG. 13). Each scan vector end gap300may have a width WG. As noted, conventional pre-assigned build strategy parameters92(FIG. 2) typically indicate a stitching region should be built vertically upon itself in each layer of object102, like stitching region264inFIG. 9. In this case, scan vector end gaps300typically are aligned vertically within a stitching region, creating a planar area in object102in which the gaps are stacked upon one another. In accordance with another embodiment of the disclosure, scan vector end gaps300may be selectively modified by changing their size, e.g., by increasing or decreasing any one or more of them in width. That is, the build strategy parameter modifying may include modifying a size (WG) of at least one of the plurality of spaced, scan vector end gaps300. In this fashion, where it is advantageous, for example, to have scan vector end gaps closer together or farther apart, e.g., to strengthen an area or to avoid some object feature, the change can be selectively made. As will be understood, changing positions of scan vector end gaps also changes the length of certain scan vectors202. The modification can be made, for example, by drag and drop techniques, or textual inputs.

In another embodiment shown inFIG. 13, stitching region312may have a centerline C defining a first half320and a second half322thereof in selected region324. Here, build strategy parameter modifying may include alternatingly positioning the plurality of spaced, scan vector end gaps300in first half320and second half322of stitching region324. That is, each scan vector end gap300is in a different half of stitching region324than adjacent scan vector end gaps. In this fashion, scan vector end gaps300do not overlap within stitching region312. In another embodiment, shown inFIG. 14, the build strategy parameter modifying may include randomly selecting a position of the plurality of spaced scan vector end gaps300between first half320and second half322of stitching region312. That is, positions of scan vector end gaps300are arbitrarily selected. The selected region within which scan vector modifications are made can be an areal region, a volume or even select scan vector(s).

As noted, embodiments of the disclosure may be applicable to AM systems employing any number of irradiation devices110,112,114,116, including one. In this regard, certain build strategy parameters are used for both single and multiple irradiation device AM systems. The following description addresses some examples of those build strategy parameters.

With continuing reference toFIG. 14, in another embodiment, the plurality of pre-assigned build strategy parameters92(FIG. 2) may include a set of preset scan vector parameters for each layer of object102. Each set of preset scan vector parameters may include, for example, scan vector spacing, scan vector width, scan vector length, scan vector path, e.g., linear or curved, interior or boundary, etc. In this case, step S10may include selecting a region including one or more scan vectors202. That is, the selected region is defined by at least one scan vector used to build object102in object code124O. For example, selected region324may be an areal space including a number of scan vectors202A,202B,202X as inFIG. 14, or a single scan vector such as scan vector202X. In step S12, the selective modifying may include changing at least one scan vector parameter from the set of preset scan vector parameters for the region of the layer of the object. For example, the build strategy parameter modifying may include changing a beam size of at least one irradiation device110,112,114,116for the region, e.g., one or more scan vectors202in the region, from the plurality of pre-assigned build strategy parameters. Alternatively, a beam size of a single scan vector202X may be changed (shown wider).FIG. 15shows another example in which spacing between certain scan vectors202(which are selected regions) have been selectively modified, e.g., they are not equally spaced.

Referring toFIG. 16, an illustrative interface250in the form of a GUI252, created by region modifier90, is shown. In this example, a two dimensional representation of selected region246of a layer of an object102with, for example, laser assignments, e.g.,110,112, and stitching region264, is shown. A dropdown window350may provide a list of pre-assigned build strategy parameters92, e.g., laser assignment (assign), spacing, width, etc., allowing selection of one or more pre-assigned build strategy parameters for modification. An input window352may be provided for modifying a selected pre-assigned build strategy parameter92. In addition, a build strategy parameter add window356may be created by region modifier90with a list of build strategy parameters358that can be added. The list of build strategy parameters to be added358may include those not listed in the pre-assigned build strategy parameters92. An appropriate input window360may also be created by region modifier90for inputting an appropriate value for the selected additional build strategy parameter(s)358. A selector362may be provided for GUI-based selecting, dragging, reshaping actions, etc., relative to positions of visually rendered and modifiable build strategy parameters such as the position of stitching region264. It is noted that the example GUI252is just one example of a large variety of well understood techniques for modifying and/or adding build strategy parameters.

The present disclosure is described herein with reference to flow diagram illustrations and/or block diagrams of methods, systems and computer program products according to embodiments of the disclosure. It will be understood that each block of the flow diagram illustrations and/or block diagrams, and combinations of blocks in the flow diagram illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer (e.g., control system120of AM system100, or region modifier90), or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flow diagram and/or block diagram block or blocks. In this regard, each block in the flow diagram or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flow diagram illustration, and combinations of blocks in the block diagrams and/or flow diagram illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

The technical advantage of embodiments of the disclosure is to provide a technique to manually selectively modify a selected region of an object in object code used for additive manufacture. This functionality is in contrast to automated systems that change object code for a specific purpose without user intervention. In one embodiment, the present disclosure allows for multiple irradiation devices to work on a single object or portion of an object where the user can specifically define build strategy parameters for the stitching region between the irradiation devices. The user has manual control of, for example, the stitching region locations, stitching characteristics, and balance of work between the multiple irradiation devices. Embodiments of the disclosure also allow for a customization of selected regions defined on a scan vector by scan vector basis. Embodiments of the disclosure are CAD model driven and allow direct scan path editing techniques. The disclosure is applicable to a wide variety of additive manufacturing techniques.