Patent Application
20200108559
The present disclosure generally relates to an additive manufacturing apparatus. More specifically, the present disclosure relates to nozzles for an additive manufacturing apparatus that can be reconfigured, readily exchanged and moved to improve build performance.
Additive manufacturing (AM) encompasses a variety of technologies for producing components in an additive, layer-wise fashion. In powder bed fusion which is one of the most popular AM technologies, a focused energy beam is used to fuse powder particles together on a layer-wise basis. The energy beam may be either an electron beam or laser. Laser powder bed fusion processes are referred to in the industry by many different names, the most common of which being selective laser sintering (SLS) and selective laser melting (SLM), depending on the nature of the powder fusion process. When the powder to be fused is metal, the terms direct metal laser sintering (DMLS) and direct metal laser melting (DMLM) are commonly used.
Referring to
Selected portions 107 of the powder layer are irradiated in each layer using, for example, a laser beam 108. After irradiation, the build plate 102 is lowered by a distance equal to one layer thickness in the object 109 being built. A subsequent layer of powder is then coated over the last layer and the process repeated until the object 109 is complete. The laser beam 108 movement is controlled using galvo scanner 110. The laser source (not shown) may be transported from a laser source (not shown) using a fiber optic cable. The selective irradiation is conducted in a manner to build object 109 an accordance with computer-aided design (CAD) data.
Powder bed technologies have demonstrated the best resolution capabilities of all known metal additive manufacturing technologies. However, since the build needs to take place in the powder bed, the size of object to be built is limited by the size of the machine's powder bed. Increasing the size of the powder bed has limits due to the needed large angle of incidence that can lower scan quality, and weight of the powder bed which can exceed the capabilities of steppers used to lower the build platform. In view of the foregoing, there remains a need for a manufacturing apparatus that can handle production of large objects with improved precision and in a manner that is both time and cost-efficient with a minimal waste of raw materials.
In a first aspect, an additive manufacturing apparatus has at least one build unit with a powder delivery mechanism, a powder recoating mechanism and an irradiation beam directing mechanism. The additive manufacturing apparatus also includes a rotating build platform, a gas inlet nozzle and a gas exhaust nozzle. The gas nozzles direct gas across the build platform or build site or evacuate gas therefrom. A positioning mechanism is connected to the gas inlet nozzle and the gas exhaust nozzle, and the positioning mechanism provides independent movement of the gas inlet nozzle and the gas exhaust nozzle.
In a second aspect, an additive manufacturing apparatus includes at least one build unit having a powder delivery mechanism, a powder recoating mechanism and an irradiation beam directing mechanism. The additive manufacturing apparatus also includes a build platform, a gas inlet nozzle and a gas exhaust nozzle, as well as a positioning mechanism connected to the gas inlet nozzle and the gas exhaust nozzle. The positioning mechanism is configured to provide independent movement of the gas inlet nozzle and the gas exhaust nozzle. The positioning mechanism has a first articulated arm connected to the gas inlet nozzle, and a second articulated arm connected to the gas exhaust nozzle.
The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details.
The present invention provides an apparatus and embodiments of the apparatus that can be used to perform powder-based additive layer manufacturing of a large object. Examples of powder-based additive layer manufacturing include but are not limited to selective laser sintering (SLS), selective laser melting (SLM), direct metal laser sintering (DMLS), direct metal laser melting (DMLM) and electron beam melting (EBM) processes.
An additive manufacturing apparatus provided herein includes a build unit assembly, which is configured to include several components that are essential for additively manufacturing high-precision, large-scale objects. These build components include, for example, a powder recoating mechanism and an irradiation beam directing mechanism. The build unit is advantageously attached to a positioning mechanism that allows two- or three-dimensional movement (along x-, y- and z-axes) throughout the build environment, as well as rotation of the build unit in a way that allows leveling of the powder in any direction desired. The positioning mechanism may be a gantry, a delta robot, a cable robot, a robotic arm, a belt drive, or the like.
Aside from the build unit, an additive manufacturing apparatus of the present invention also includes a rotating build platform, or any kind of additive manufacturing machine where the scan head moves relative to the build plate. For example, this includes an X, Y, Z gantry system where the processing area moves about the build plate. Preferably, this build platform has a substantially circular configuration but is not so limited. Since the build unit of the apparatus is mobile, this eliminates the need to lower the build platform as successive layers of powder are built up, as it is in conventional powder bed systems. Accordingly, the rotating build platform of the present invention is preferably vertically stationary.
The build unit 202 may be configured to include several components for additively manufacturing a high-precision, large-scale object or multiple smaller objects. A mobile build unit 202 includes a powder delivery mechanism, a powder recoating mechanism, a gas-flow mechanism with a gas-flow zone and an irradiation beam directing mechanism.
The build unit positioning mechanism 225 may be an X-Y-Z gantry that has one or more x-crossbeams 225X (one shown in
The rotating build platform 210 may be a rigid, ring-shaped or annular structure (i.e. with an inner central hole) configured to rotate 360° around the center of rotation W, or the build platform may be a disk without a central hole. The rotating build platform 210 may be secured to an end mount of a motor 216 that is operable to selectively rotate the rotating build platform 210 around the center of rotation W such that the build platform 210 moves in a circular path. The motor 216 may be further secured to a stationary support structure 228. The motor may also be located elsewhere near the apparatus and mechanically connected with the build platform via a belt for translating motion of the motor to the build platform.
The gas-flow mechanism comprises a nozzle positioning mechanism 240 having articulated arms 245 attached to a gas inlet nozzle 241 and a gas exhaust nozzle 242. Arm sections are joined by joints 246 that permit each arm section to articulate and move in three dimensions. The gas inlet nozzle 241 and the gas exhaust nozzle 242 are used to direct a flow of inert gas across (e.g., from left to right in
Each of the gas inlet nozzle 241 and the gas exhaust nozzle 242 are configured to be readily replaceable and exchangeable as desired for the specific build or object being built. Each nozzle 241, 242 can be easily and quickly removed from the nozzle positioning mechanism 240 and replaced with another nozzle having a different size and/or shape.
Representative examples of suitable powder materials can include metallic alloy, polymer, or ceramic powders. Exemplary metallic powder materials are stainless steel alloys, cobalt-chrome, aluminum alloys, titanium alloys, nickel based superalloys, and cobalt based superalloys. In addition, suitable alloys may include those that have been engineered to have good oxidation resistance, known “superalloys” which have acceptable strength at the elevated temperatures of operation in a gas turbine engine, e.g. Hastelloy, Inconel alloys (e.g., IN 738, IN 792, IN 939), Rene alloys (e.g., Rene N4, Rene N5, Rene 80, Rene 142, Rene 195), Haynes alloys, Mar M, CM 247, CM 247 LC, C263, 718, X-750, ECY 768, 282, X45, PWA 1483 and CMSX (e.g. CMSX-4) single crystal alloys. The manufactured objects of the present invention may be formed with one or more selected crystalline microstructures, such as directionally solidified (“DS”) or single-crystal (“SX”).
This written description uses examples to disclose the invention, including the preferred embodiments, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspect, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application.
