Flexible fixture for directional energy deposition and build station assembly including same

Abstract

A build table assembly (104) for supporting a component (102), the build table assembly (104) comprising: a base (202) having an upper surface (302); a frame (110) extending from an upper surface (302) of the base (202), the frame (110) defining an upper wall (310); a rim (112) formed on an upper wall (310) of the frame (110); and a plurality of fixture segments (114) positioned on the rim (112) opposite the upper wall (310) of the frame (110), the plurality of fixture segments (114) defining an arcuate build surface (116) on which the component (102) is built, the plurality of fixture segments (114) being spaced apart from each other.

Description

Technical Field

[0001] The present disclosure relates generally to directed energy deposition ("DED") additive manufacturing systems and methods, and more particularly, to DED systems and methods for reducing stress on a part during material deposition. Background Art

[0002] Additive manufacturing is an emerging set of technologies for manufacturing three-dimensional objects directly from a digital model through additive processes, typically by depositing material layer by layer and joining successive layers into place. DED is an additive manufacturing process used to make new parts and / or repair existing parts or add additional material to existing parts. Using DED, parts can be manufactured layer by layer using a directed stream of feedstock from a deposition nozzle. DED equipment uses a focused energy source, such as a laser or electron beam, to melt the feedstock and simultaneously deposit the molten material on a specified surface, where this molten material solidifies and fuses with other deposited material to form the part layer by layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The embodiments presented in the drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments may be understood when read in conjunction with the following drawings, in which like structures are represented by like reference numerals, and in which:

[0004] Figure 1 schematically depicts a perspective view of an additive manufacturing system according to one or more embodiments shown and described herein;

[0005] Figure 2 Schematically depicts a schematic diagram of a device according to one or more embodiments shown and described herein. Figure 1 A perspective view of a build table assembly of an additive manufacturing system;

[0006] Figure 3 Schematically depicts a schematic diagram of a device according to one or more embodiments shown and described herein. Figure 2 a perspective view of a fixture segment of a build table assembly; and

[0007] Figure 4 Schematically depicts a schematic diagram of a device according to one or more embodiments shown and described herein. Figure 2 A partial cross-sectional view of the build platform assembly. DETAILED DESCRIPTION

[0008] Reference will now be made in detail to the present embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter references to refer to features in the drawings. Like or similar reference numbers in the drawings and description have been used to refer to like or similar parts of the present disclosure.

[0009] The terms "coupled," "fixed," "attached to," and the like refer to both direct coupling, fixing, or attachment as well as indirect coupling, fixing, or attachment through one or more intermediate components or features, unless otherwise specified herein.

[0010] As used herein, the term "residual stress" refers to the magnitude and direction of stresses remaining in a part after an additive manufacturing process, such as a combination of thermal stresses resulting from cooling after deposition and mechanical stresses resulting from applied compressive forces.

[0011] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0012] In a context such as “at least one of A, B, and C,” the term “at least one of” means only A, only B, only C, or any combination of A, B, and C.

[0013] As used in this application, describing any part (e.g., layer, film, region, area or panel) as being on (e.g., positioned on, located on, disposed on or formed on, etc.) another part in any manner indicates that the referenced part is in contact with the other part, or that the referenced part is above the other part with one or more intermediate parts located therebetween.

[0014] As used herein, connection references (e.g., attachment, coupling, connection, and engagement) may include intermediate members between the elements to which the connection reference refers and / or relative movement between these elements, unless otherwise specified. Thus, a connection reference does not necessarily mean that two elements are directly connected and / or have a fixed relationship to each other. As used herein, a statement that any part is "in contact with" another part means that there is no intermediate part between the two parts.

[0015] Unless otherwise specifically stated, descriptors such as "first," "second," "third," etc., are used herein without implying or otherwise indicating any meaning of priority, physical order, arrangement in a list, and / or ordering in any manner, but are merely used as labels and / or arbitrary names to distinguish elements to facilitate understanding of the disclosed examples. In some examples, the descriptor "first" may be used to refer to an element in the detailed description, while the same element may be referred to by a different descriptor (e.g., "second" or "third") in the claims. In this case, it should be understood that such descriptors are only used to clearly identify those elements that may share the same name in other ways, for example.

[0016] As used herein throughout the specification and claims, approximating language is used to modify any quantitative representation that can be permissibly varied without resulting in a change in the basic function to which it is related. Thus, a value modified by one or more terms (e.g., "approximately," "approximately," and "substantially") is not limited to the precise value specified. In at least some cases, approximate language may correspond to the precision of an instrument used to measure a value, or the precision of a method or machine used to construct or manufacture a component and / or system. For example, approximate language may refer to within a 10% margin.

[0017] Here and throughout the specification and claims, range limitations are combined and interchanged, and unless context or language indicates otherwise, these ranges are identified and include all sub-ranges contained therein. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0018] Conventional additive manufacturing processes, such as DED systems, use a solid platform, plate, or fixture that is attached to the machine by bolted joints or other suitable means on which the part is built. When manufacturing large parts, such as those greater than 0.5 meters in diameter, isostatic fixtures that are movable in at least one axis are employed to reduce residual stresses on the fixture and the part during manufacturing. These fixtures may include a plate with one or more (in some cases three) slots through which bolts extend and secure the fixture to the machine. The slots allow the bolts to move within the slots to allow the fixture to expand and contract in at least one axis as the fixture and the part are heated and subsequently cooled during the manufacturing process.

[0019] However, the cost of these plates for large parts can be high relative to the total cost of producing the part, even considering that the fixture may be reused for other parts. In addition, part unloading operations to remove the part from the fixture, such as removing bolts, can result in a sudden release of residual stresses that can cause part cracking or failure.

[0020] Therefore, it is desirable to provide a flexible fixture that includes a plurality of sectors placed together to form a base on which the first layer of the formed part will be deposited. In the embodiment described herein, the plurality of sectors form a ring on which the cylindrical part is built. As described in detail herein, the sectors are not physically connected to each other, thereby allowing the layers of the part to expand and contract in a direction during the manufacturing process. This movement allows for the reduction of excessive residual stresses formed in the fixture and part to comply with thermal cycles during the manufacturing process.

[0021] The inventors of the present disclosure have developed an architecture for a fixture for a part (e.g., a cylindrical part). In particular, the inventors proceeded in a manner to design a fixture with given dimensions and material properties based on the dimensions and material properties of the part to be manufactured. In the course of studying / evaluating various fixture properties that are considered feasible for optimally reducing residual stresses formed in the part, the inventors unexpectedly discovered that there is a certain relationship between the tendency of part failure and the stress ratio between the part and the fixture. In particular, the inventors discovered that when the stress ratio between the part and the fixture is less than 1.0, part failures such as deformation and cracking are less likely to occur. By performing the calculations described in the following expression, it is possible to eliminate unfeasible designs and use appropriate materials for the fixture segment 114 based on the specific part 102 to be built, which materials were previously unknown without the following expression. Such an unfeasible design of the fixture segment 114 will result in excessive stress accumulation in the part 102 and / or part failure during the manufacturing process. In addition, the inventors discovered that a specific ratio indicates the extent to which the fixture is utilized. For example, a smaller ratio indicates that the quality of the material forming the fixture may be too high and a lower quality, such as a weaker material, can be used while still avoiding part failure. On the other hand, a larger ratio indicates that the part is more likely to fail and a stronger material should be used to form the fixture. Thus, given the cumulative stress level in the component 102, the ratio identifies the optimal design of the fixture segment 114.

[0022] Reference now Figure 1 , a DED additive manufacturing system 100 (hereinafter, system 100) according to one or more embodiments of the present disclosure is shown. The system 100 is configured to construct or build a part 102 from a raw material. The part 102 has an inner surface 102a, an opposite outer surface 102b, and a layer or surface 102c being built. In the example shown, the part 102 is a cylindrical part, but in other examples, the part 102 can have different geometric shapes.

[0023] As shown, system 100 includes a build table assembly 104. In an embodiment, at least a portion of build table assembly 104 is configured to rotate about a build table axis B of build table assembly 104, which extends parallel to the Z axis of the coordinate axis, thereby rotating a component 102 supported on build table assembly 104. Therefore, build table assembly 104 is a rotating build table assembly 104. However, it should be understood that in other embodiments, build table assembly 104 is fixed, so that when component 102 is being built, build table assembly 104 does not rotate.

[0024] In particular, as described in greater detail herein, build table assembly 104 includes base 106 supported on platform 108, frame 110 extending from base 106 in a direction opposite platform 108, and rim 112 disposed on frame 110 opposite base 106. Build table assembly 104 also includes a plurality of fixture segments 114 disposed on rim 112 of frame 110 and surrounding rim 112. Each fixture segment 114 defines an arcuate build surface 116 on which part 102 is built and supported.

[0025] As described herein, any number of fixture segments 114 may be used, with the total number of fixture segments 114 depending on the length of each fixture segment 114 relative to a given length of the build surface 116. For example, in embodiments where each fixture segment 114 has a reduced length, a greater number of fixture segments 114 are used. Alternatively, in embodiments where each fixture segment 114 has an increased length, a smaller number of fixture segments 114 are used. As described in more detail herein, each fixture segment 114 is fixed to the edge 112 of the build table assembly 104. However, the fixture segments 114 are not fixed to each other. Therefore, the fixture segments 114 are allowed to move radially during the manufacturing process to allow the component 102 to expand and contract. However, it should be understood that the fixture segments 114 may also or alternatively move in any direction during expansion and contraction. As shown, the frame 110 and therefore the edge 112 have a cylindrical geometry, and the component 102 is built thereon. Therefore, the component 102 similarly has a cylindrical cross-section. The manner in which fixture segments 114 are secured to edge 112 of build table assembly 104 is described in greater detail herein.

[0026] In the illustrated embodiment, the base 106 of the build table assembly 104 rotates relative to the platform 108. Therefore, the actuator 118 can be disposed in the platform 108 or the base 106 for rotating the build table assembly 104 in a clockwise or counterclockwise rotational direction about the build table axis B. In the illustrated embodiment, the actuator 118 rotates the build table assembly 104 in a counterclockwise direction R about the build table axis B. In addition, as described below, the actuator 118 rotates the build table assembly 104 at a variable rotational speed. In some examples, the base 106 is also configured to translate the build table assembly 104 vertically along the build table axis B.

[0027] The system 100 also includes a deposition assembly 120. The deposition assembly 120 has a deposition head 122 through which a molten feedstock stream can be deposited to produce the part 102. As described herein, the molten feedstock is deposited or output from the deposition head 122 at a deposition rate. The deposition assembly 120 includes a structure that adjustably and movably supports the deposition head 122. In the example shown, the deposition assembly 120 includes a robotic arm 124, which includes a plurality of links 126 that can be articulated relative to each other to adjust the position of the deposition head 122. In the embodiment shown, the deposition head 122 is supported on the most distal link 128 of the plurality of links 126. Therefore, it should be understood that the deposition head 122 and the build table assembly 104 can move relative to each other. For example, the robotic arm 124 may include one or more actuators that rotate the links 126, 128 of the robotic arm 124 relative to each other, thereby moving the robotic arm 124 and the deposition head 122 supported thereon relative to the build table assembly 104. It will be appreciated that the robotic arm 124 may have various other configurations for moving and adjusting the position of the deposition head 122 in multiple degrees of freedom without departing from the present disclosure.

[0028] The deposition assembly 120 includes an energy source 130 and a material source 132. The material source 132 is configured to deliver a feedstock (e.g., a metal or polymer-based wire) to the deposition head 122, where the feedstock is deposited on the build table assembly 104. In the illustrated embodiment, the material source 132 is a material reel and feeder system configured to deliver a wire 134 to the deposition head 122. Thus, the material source 132 can accommodate the wire 134 that is fed to the deposition head 122. For example, the wire 134 can be delivered to the deposition head 122 outside the robot 124, or delivered through an inner cavity of the robot 124 connected to the deposition head 122. In an embodiment, the wire 134 can be a metal or polymer-based wire. In other embodiments, the material source 132 can include a pressurized powder source that delivers a pressurized powder feedstock stream to one or more material delivery devices (e.g., nozzles, valves, etc.) of the deposition head 122, rather than a material reel and feeder system configured to deliver the wire 134. In accordance with the present disclosure, any suitable feedstock that can be used in a DED process may be used.

[0029] Depending on the implementation, energy source 130 can take various forms. In the example shown, energy source 130 is a plasma transferred arc heat source. In other examples, energy source 130 can include a laser source and an optical device configured to direct a laser beam having a desired energy density to a build surface 116 of fixture segment 114. In some examples, energy source 130 can include an electron emitter connected to a power source and at least one focusing coil configured to direct the electron beam to component 102 being constructed on build surface 116 of fixture segment 114. In such an embodiment, build table assembly 104 can be placed in a build chamber (not shown) under vacuum or with an oxygen reduced environment. However, energy source 130 can take various other forms, such as a plasma source, an electron beam source, a resistive heater, etc.

[0030] According to the present disclosure, the system 100 may include any number of energy sources and material sources. In addition, the raw materials from the material source 132 can be delivered to the deposition head 122 in various ways for discharge onto the build table assembly 104. For example, in an embodiment, the line 134 from the material source 132 can be divided into two or more material feeds, which are delivered to the deposition head 122 by the robot 124. Each material feed can leave the deposition head 122 at a separate delivery nozzle. In addition, multiple energy sources can be used to form the same molten pool, such as arc heat sources and lasers.

[0031] In operation, one or more feedstock streams are fed into the path of the energy beam from energy source 130 and emitted by deposition head 122 as a stream of molten feedstock. In particular, at the overlap point between the energy beam and the feedstock stream, where the energy beam has the necessary energy density, the energy can heat the feedstock to a sufficient degree to form a molten pool on build surface 116. The molten feedstock can be continuously fed through and deposited from deposition head 122 so that the molten pool forms a pattern corresponding to the movement pattern of deposition head 122 and build table assembly 104. The movement of deposition head 122 and build table assembly 104 can be determined based on the desired shape of part 102 being built so that when the molten pool cools, the feedstock solidifies to form a portion of part 102. For example, rotation of build table assembly 104 about build table axis B as deposition head 122 deposits the molten pool results in a circular stream of molten feedstock that will layer upon itself and build a cylindrical part, such as part 102, as build table assembly 104 continues to rotate over time. Additionally, as shown, robotic arm 124 can position deposition head 122 radially toward or away from build table axis B to produce non-circular parts of varying sizes and diameters.

[0032] The system 100 also includes a compression device 140. The compression device 140 is positioned proximate to the deposition assembly 120 and is operable to continuously apply a compressive load to the deposited feedstock that forms the component 102. As described herein, the compression device 140 is configured to apply a compressive load to the component 102 during or while in a deposition phase (e.g., a compression phase) in which the deposition assembly 120 deposits a molten feedstock stream to build the component 102. In the illustrated embodiment, the compression device 140 includes at least one actuator and a load source 144, as further described below.

[0033] Typically, at least one actuator is configured to move and manipulate the orientation of the load source 144 relative to the portion of the component 102 to which the compressive load is to be applied. The load source 144 applies a force to the deposited material to induce a desired level of strain in the deposited layer and / or improve the mechanical properties of the component 102.

[0034] As described herein, in embodiments, the robotic arm 124 is operable to position the deposition head 122 near the load source 144, and / or the compression device 140 is operable to position the load source 144 near the deposition head 122. If cold rolling is intended, the distance between the load source 144 and the deposition head 122 may be increased, for example, by rotating the build table assembly 104 in the opposite clockwise direction. In this manner, the deposition head 122 may be operated to deposit molten feedstock in a molten pool while the load source 144 applies a compressive load to the part 102, wherein the load source 144 trails the deposition head 122, such that the load source 144 applies a load to the previously deposited material a short time thereafter, depending on the rotation speed of the build table assembly 104. Thus, the compression device 140 may apply a compressive load to the part 102, at least near the molten pool of the part 102, while the deposition head 122 forms the molten pool. This not only reduces machine cycle time, but also allows the compressive load to be applied to the part 102 at a constant temperature and at a temperature suitable for providing a forged-like quality to the part 102. However, as discussed herein, build table assembly 104 may be used independently of robotic arm 124 and compression device 140 .

[0035] In an embodiment, the system 100 may further include a controller 150. The controller 150 may be communicatively coupled to the build table assembly 104, the deposition assembly 120, and / or the compression device 140. Thus, the controller 150 may communicate with the base 106, the robotic arm 124, and / or the compression device 140 to control their operation. For example, the controller 150 may include a processor and a memory storing computer-readable instructions that dynamically control the rotation direction and / or rotation speed of the build table assembly 104 around the build table axis B, the vertical translation of the build table assembly 104 along the build table axis B, the position and orientation of the deposition head 122 in space via the robotic arm 124, the position and orientation of the load source 144 in space, and / or the magnitude of the compressive load applied by the load source 144. The controller 150 may also be configured to control the feed rate of the raw material being fed to the deposition head 122 and / or the deposition rate of the molten raw material stream output from the deposition head 122.

[0036] In an embodiment, system 100 may have various sensors configured to communicate with controller 150, and controller 150 may utilize data from the various sensors to control the operation of build table assembly 104, deposition assembly 120, and / or compression device 140 as needed to manufacture a particular part 102.

[0037] In the example shown, deposition head 122 deposits feedstock to fabricate component 102 on build table assembly 104 while build table assembly 104 rotates in a counterclockwise direction R about build table axis B. As build table assembly 104 continues to rotate component 102 in the counterclockwise direction R, feedstock previously deposited by deposition head 122 will encounter load source 144 after being deposited from deposition head 122. Thus, in the illustrated embodiment, deposition head 122 acts on a particular portion of component 102 before load source 144 acts on the particular portion of component 102, and similarly, load source 144 also acts on the particular portion of component 102 after deposition head 122 has acted on the particular portion of component 102. In other words, because in the illustrated embodiment, build table assembly 104 rotates in the counterclockwise direction R, deposition head 122 is positioned before load source 144, and load source 144 is positioned after deposition head 122.

[0038] In an embodiment, the compression device 140 may include a slidable support structure 210 configured to slide laterally in the Y-axis direction relative to the base 202. In an embodiment, the compression device 140 may include a slidable positioning structure 220 configured to slide vertically in the Z-axis direction relative to the slidable support structure 210. In an embodiment, the compression device 140 includes an adjustable support member 230 that supports a compression head 246 that includes a load source 144. The adjustable support member 230 is coupled to the slidable positioning structure 220 and is configured to allow relative rotation of the compression head 246.

[0039] In an embodiment, the load source 144 is provided with a plurality of rollers arranged to apply a compressive load to the component 102 at various portions of the component 102. The compression head 246 is configured to rotatably hold the plurality of rollers in various orientations so as to roll over certain portions of the component 102.

[0040] Reference now Figure 2 , build platform assembly 104 is shown in more detail with Figure 1 108 and part 102 are separated. As described herein and more particularly, construction platform assembly 104 includes base 106 having upper surface 302 and an opposing lower surface 304. It should be understood that lower surface 304 of base 106 can be disposed on platform 108 ( Figure 1 ) and, in an embodiment, is rotatably and translationally fixed thereto via actuator 118 so that base 106 and therefore other components of build table assembly 104 coupled to base 106 can be rotated and vertically translated relative to platform 108. Figure 2 As shown, the base 106 has a circular geometry. However, it should be understood that the base 106 may have any suitable geometry other than that described herein.

[0041] The build table assembly 104 also includes a frame 110 that extends from the upper surface 302 of the base 106 to the platform 108 ( Figure 1 ) in a direction opposite to the inner surface 306. The frame 110 includes an inner surface 306 and an outer surface 308 opposite to the inner surface 306. The frame 110 also includes an upper wall 310 disposed opposite to the upper surface 302 of the base 106. The distance between the inner surface 306 and the outer surface 308 of the frame 110 defines a frame thickness. A plurality of recesses 312 are formed in the outer surface 308 of the frame 110 and extend radially toward the inner surface 306 of the frame 110. The recesses 312 define fins 314 extending between the upper wall 310 of the frame 110 and the base 106. In an embodiment, the recesses 312 each have the same width such that the fins 314 are equally spaced apart from one another along the entire circumference of the outer surface 308 of the frame 110. Figure 2As shown, the frame 110 has a generally circular geometry, although the recess 312 is formed in the outer surface 308 of the frame 110. However, it should be understood that the frame 110 may have any suitable geometry other than that described herein.

[0042] Build table assembly 104 also includes rim 112, which is disposed on upper wall 310 of frame 110 and completely surrounds upper wall 310 of frame 110. Rim 112 includes inner surface 316 and outer surface 318 opposite inner surface 316. Rim 112 also includes upper surface 320 opposite upper wall 310 of frame 110, which extends between outer surface 318 and inner surface 316 of rim 112. The distance between inner surface 316 and outer surface 318 of rim 112 defines the thickness of the rim. Figure 2 As shown, the thickness of the edge is less than the thickness of the frame. In an embodiment, the edge 112 and the upper wall 310 of the frame 110 are formed as an integral, unitary structure. In other embodiments, the edge 112 is removably fixed to the upper wall 310 of the frame 110. Figure 2 As shown, the rim 112 has a circular geometry. However, it should be understood that the rim 112 may have any suitable geometry other than that described herein.

[0043] The build table assembly 104 also includes a plurality of fixture segments 114 disposed on the edge 112. Figure 2 As shown, build table assembly 104 includes four fixture segments 114 that are formed around edge 112. However, it should be understood that build table assembly 104 may include any suitable number of fixture segments 114 based on the circumference of edge 112. Figure 2 As shown in FIG. 1 and discussed in greater detail herein, each fixture segment 114 is secured to the edge 112 by a plurality of fasteners 322. Specifically, as shown in FIG. Figure 2 As shown, each fixture segment 114 includes two or more fasteners 322, such as four fasteners 322 received within the corresponding fixture segment 114. However, it should be understood that any suitable number of fasteners 322 may be used to secure each fixture segment 114 to the rim 112 and frame 110, such as three fasteners 322, five fasteners 322, and more than five fasteners 322.

[0044] like Figure 31, a single fixture segment 114 is depicted. It should be understood that each fixture segment 114 may include the same structure. Therefore, similar parts of each fixture segment 114 will be represented by similar reference numerals. Each fixture segment 114 has an arcuate shape and includes an inner surface 324 and an outer surface 326 opposite the inner surface 324, and the inner surface 324 and the outer surface 326 define a fixture thickness. The fixture thickness of each fixture segment 114 can also be defined by the difference between the inner radius of the fixture segment 114 and the outer radius of the fixture segment 114, the inner radius of the fixture segment 114 being the inner radius of the fixture segment 114 at the build table axis B ( Figure 2 ) and the inner surface 324 of the fixture segment 114, the outer radius of the fixture segment 114 being measured between the build table axis B ( Figure 2 ) and the outer surface 326 of the fixture segment 114. The fixture segment 114 also includes an upper surface 328 and a lower surface 330 opposite the upper surface 328. The upper surface 328 and the lower surface 330 extend between the inner surface 324 and the outer surface 326.

[0045] The fixture segment 114 includes a plurality of cavities 332 formed therein. As shown, the fixture segment 114 has four cavities 332 formed therein. However, it should be understood that any suitable number of cavities 332 may be formed in the fixture segment 114, such as, for example, three cavities 332, five cavities 332, and more than five cavities 332. Specifically, the number of cavities 332 formed in the fixture segment 114 corresponds to the number of fasteners 322 ( Figure 2 ). In an embodiment, each cavity 332 has a rounded shape and defines a sill 338. As shown, a hole 339 is formed in each cavity 332 of the fixture segment 114, the hole 339 extending from the sill 338 through the lower surface 330 of the fixture segment 114 to allow a corresponding fastener 322 to extend therethrough.

[0046] Reference now Figure 4 , depicts a cross-sectional view of a fixture segment 114 disposed on a rim 112. As shown, the fixture thickness of the fixture segment 114 is substantially equal to the rim thickness. Figure 4As shown, an upper nut 340 is disposed within each cavity 332 formed in the fixture segment 114. The upper nut 340 can be positioned within the cavity 332 through the outer surface 326 of the fixture segment 114. A hole 348 is formed in the upper nut 340 to allow the fastener 322 to extend therethrough. An internal thread 349 is formed within the hole 348 of the upper nut 340. In an embodiment, the upper nut 340 has a spherical lower surface 341 that provides an increased thickness at the center of the upper nut 340. In such an embodiment, an upper washer 343 is disposed between the upper nut 340 and the sill 338 of the cavity 332. The upper washer 343 has a spherical upper surface 345 that provides a reduced thickness at the center of the upper washer 343 corresponding to the taper of the spherical lower surface 341 of the upper nut 340. Thus, the spherical upper surface 345 of the upper washer 343 mates with the spherical lower surface 341 of the upper nut 340. The presence of the upper washer 343 having the spherical upper surface 345 that mates with the spherical lower surface 341 of the upper nut 340 reduces the shear load on the fastener 322 itself during tension and / or compression. However, in embodiments, it should be understood that either or both of the lower surface 341 of the upper nut 340 and the upper surface 345 of the upper washer 343 may have any suitable geometry, such as, for example, a conical shape or a frustoconical shape as opposed to a spherical shape.

[0047] Still reference Figure 4 , the fastener 322 includes a shaft 350 having a first end portion 352, a second end portion 354 opposite to the first end portion 352, and a body 356 extending between the first end portion 352 and the second end portion 354. The body 356 of the shaft 350 has a shaft diameter. The shaft 350 has an external thread 358 disposed at the first end portion 352 for engaging the internal thread 349 of the upper nut 340. Therefore, the first end portion 352 of the shaft 350 is received in and engaged with the internal thread 349 of the upper nut 340 to fix the first end portion 352 of the shaft 350 to the fixture segment 114. The shaft 350 of the fastener 322 extends through a channel 360 formed in the rim 112 and a channel 362 formed in the upper wall 310 of the frame 110. Therefore, the channel 360 formed in the rim 112 is coaxial with the channel 362 formed in the upper wall 310 of the frame 110. The channel 360 formed in the rim 112 and the channel 362 formed in the upper wall 310 of the frame 110 have a channel diameter that is greater than the shaft diameter.

[0048] The second end portion 354 of the fastener 322 defines a head 355 having a diameter greater than the diameter of the shaft. The second end portion 354 terminates in a corresponding recess 312 formed in the outer surface 308 of the frame 110. In an embodiment, a lower planar washer 366 is disposed between the head 355 of the fastener 322 and the upper wall 310 of the frame 110. In addition, in an embodiment, a lower washer 357 is disposed between the head 355 of the fastener 322 and the lower planar washer 366. The lower washer 357 may include a first lower washer portion 359 and a second lower washer portion 361. The first lower washer portion 359 includes a planar upper surface 363 and a spherical lower surface 365 opposite to the planar upper surface 363. The spherical lower surface 365 of the first lower washer portion 359 provides a reduced thickness at the center of the first lower washer portion 359. The second lower washer portion 361 includes a planar lower surface 367 and a spherical upper surface 369 opposite to the planar lower surface 367. The spherical upper surface 369 of the second lower gasket portion 361 provides an increased thickness at the center of the second lower gasket portion 361. Thus, the spherical lower surface 365 of the first lower gasket portion 359 mates with the spherical upper surface 369 of the second lower gasket portion 363. The presence of the first lower gasket portion 361 having a spherical lower surface 365 that mates with the spherical upper surface 369 of the second lower gasket portion 363 reduces the shear load on the fastener 322 itself during tension and / or compression. However, in embodiments, it should be understood that either or both of the lower surface 365 of the first lower gasket portion 358 and the upper surface 369 of the second lower gasket portion 361 can have any suitable geometry, such as, for example, a conical shape as opposed to a spherical shape or a frusto-conical shape.

[0049] like Figure 4As shown and discussed herein, the shaft diameter is smaller than the passage diameter. Therefore, since the fastener 322 remains fixed to the fixture segment 114 at the first end portion 352 of the shaft 350 received in the upper nut 340, the fastener 322 is allowed to move radially relative to the rim 112 and the frame 110 throughout the manufacturing process of the component 102. As described herein, during the manufacturing process, the component 102 will expand radially. Therefore, the fixture segment 114 is configured to move radially relative to the rim 112 to accommodate the expansion of the component 102. To ensure that the fixture segment 114 remains fixed to the rim 112 and the frame 110, the first end portion 352 of the shaft 350 is retained in the cavity 332 formed in the corresponding fixture segment 112, while the shaft 350 remains movable in the radial direction within the passage 360 ​​of the rim 112 and the passage 362 of the frame 110. The amount of radial movement allowed for the fixture segments 114 relative to the rim 112 is limited by the difference between the shaft diameter and the channel diameter and the friction between the components caused by the locking force and the coefficient of friction. In other words, the greater the difference between the channel diameter and the shaft diameter, the greater the amount of radial movement of the fixture segments 114 relative to the rim 112.

[0050] As previously described, the inventors unexpectedly discovered that there is a relationship between the relative stress ratios between the component 102 and the fixture segment 114. Specifically, the inventors discovered that the stress ratio between the component 102 and the fixture segment 114 indicates whether a component failure is likely to occur. In particular, the inventors discovered that when the ratio is less than 1.0, a component failure is unlikely to occur. In addition, the inventors discovered that the stress ratio between the component 102 and the fixture segment 114 indicates whether the material forming the fixture segment 114 is underutilized, such that it is beneficial from a cost perspective to use a lower quality material to form a particular component 102. As a result, improvements in component quality and material efficiency are achieved.

[0051] More specifically, the specific ratio between component 102 stress and fixture segment 114 stress is determined according to expression (1):

[0052]

[0053] In the above expression (1), R s represents the stress ratio between the component 102 and the fixture segment 114, S_p represents the stress accumulated in the tangential portion of the component 102, and YS fixture represents the yield stress of the fixture segment 114, YS fastener represents the yield stress of the fastener 322, and YS upper_nut represents the yield stress of the upper nut 340. In the above expression (1), represents the integrated force (F), and N represents the number of fasteners 322 and upper nuts 340.

[0054] Initially, the component sector area (A) is determined according to expression (2) component_sector ):

[0055]

[0056] In the above expression (2), R out represents the outer radius of the fixture segment 114, R in represents the inner radius of the fixture segment 114, N fixtures represents the total number of fixture segments 114. As described herein, the outer radius and inner radius of the fixture segments 114 are measured from the build table axis B of the build table assembly 104.

[0057] The component stress S_p is determined by finite element method (FEM) analysis. Integrated force in kilonewtons (kN) According to expression (3), we can determine:

[0058]

[0059] It should be understood that the division by "1000" in the above and following expressions is only for consistency of units.

[0060] Fixture yield stress YS fixture represents a known value based on the properties of the material forming the fixture segment 114. In addition, min(YS fixture ) represents the minimum fixture yield stress, specifically the minimum yield stress of any portion of the fixture segment 114. It represents the minimum yield stress (min(YS) of any part of the fixture segment 114. fixture The integral of )) is determined according to expression (3):

[0061]

[0062] The sum of the yield stress of the fasteners∑ N (YS fastener ) is determined according to expression (5):

[0063]

[0064] Fastener yield stress (YS fastener ) represents a known value based on the properties of the material forming the fastener. In addition, the radius of the fastener 322 (Radius fastener ) is equal to half the diameter of the shaft 350 of the fastener 322. N fastenersThe total number of fasteners 322 associated with each fixture segment 114 is represented.

[0065] In addition, the sum of the yield stress of the upper nut ∑ N (YS upper_nut ) is determined according to expression (6):

[0066]

[0067] In an embodiment, the upper nut 340 and the fastener 322 may be formed of the same material. In this embodiment, the fastener yield stress (YS upper_nut ) is equal to the upper nut yield stress.

[0068] Therefore, the solution of expression (1) is equal to the solution of expression (4) plus the sum of the solutions of expression (4), expression (5), and expression (6). In other words, the stress ratio (R) between component 102 and fixture segment 114 is s ) is obtained by integrating the stress of the component Divided by the minimum fixture segment yield stress The sum of the yield stress of the fasteners∑ N (YS fastener ) and the sum of the yield stress of the upper nut∑ N (YS upper_nut ), where each result is in kN.

[0069] As described herein, the inventors have found that solutions to expression (1), such as the stress ratio (R s ), less than 1.0, ensures that component failure is unlikely to occur. This was determined based on multiple tests with different parameters, in which part failure (e.g., part rupture) occurred when the above expression was not satisfied, and part failure did not occur when the above expression was satisfied. More specifically, the inventors found that the stress ratio (R s ) to ensure full utilization of the material forming the fixture segment 114. Specifically, the inventors have found that a ratio (R s ) is sufficient to cover all possible designs of the component 102. More specifically, the inventors have found that, given the parameters of the component 102, applying a ratio (R s ) ensures that the material forming the fixture segment 114 is not over-utilized or under-utilized.

[0070] Although specific features of various embodiments may be shown in some drawings and not in other drawings, this is only for convenience. According to the principles of the present disclosure, any feature of a drawing may be referenced and / or claimed in combination with any feature of any other drawing.

[0071] This written description uses examples to disclose the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the present disclosure, including making and using any device or system and performing any combined method. The patentable scope of the present disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. These other examples are intended to fall within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ substantially from the literal language of the claims.

[0072] Further aspects are provided by the subject matter of the following clauses:

[0073] A building table assembly for supporting a component, the building table assembly comprising: a base, the base having an upper surface; a frame, the frame extending from the upper surface of the base, the frame defining an upper wall; a rim, the rim formed on the upper wall of the frame; and a plurality of fixture segments, the plurality of fixture segments being positioned on the rim, opposite to the upper wall of the frame, the plurality of fixture segments defining an arcuate building surface, the component being built on the arcuate building surface, the plurality of fixture segments being spaced apart from each other.

[0074] A construction table assembly according to the preceding clause, wherein each of the plurality of fixture segments comprises: an inner surface; an outer surface opposite the inner surface; an upper surface; a lower surface opposite the upper surface; and a plurality of cavities spaced apart from each other, the plurality of cavities extending through the outer surface and the lower surface.

[0075] A build table assembly according to any of the preceding clauses, wherein the plurality of fixture segments comprises four fixture segments.

[0076] The building table assembly according to any of the preceding clauses further comprises: a plurality of upper nuts, each of which is received in a corresponding cavity among the plurality of cavities; and a plurality of fasteners, the plurality of fasteners fixing each of the plurality of fixture segments to the edge, each of the plurality of fasteners being threadedly engaged with a corresponding upper nut to retain the plurality of fasteners in the corresponding cavity.

[0077] A build table assembly according to any of the preceding clauses, wherein each cavity has a rounded shape.

[0078] A build table assembly according to any of the preceding clauses, wherein each of the plurality of fasteners extends through a corresponding channel formed in the frame, the channel having a diameter greater than a diameter of the fastener to allow the plurality of fixture segments to move radially outward relative to the frame.

[0079] A build table assembly according to any of the preceding clauses, wherein a plurality of recesses are formed in an outer surface of the frame and define a plurality of fins, each fastener of the plurality of fasteners terminating within a corresponding recess of the plurality of recesses.

[0080] The build table assembly of claim 1, wherein a stress ratio between the component and the plurality of fixture segments is less than 1.0 and is defined by:

[0081]

[0082] Where S_p represents the stress accumulated in the tangential part of the component, YS fixture represents the yield stress of the fixture segment, YS fastener represents the yield stress of the plurality of fasteners, and YS upper_nut represents the yield stress of the upper nut.

[0083] A build table assembly according to any of the preceding clauses, wherein the stress ratio between the component and the plurality of fixture segments is equal to or greater than 0.2 and equal to or less than 0.8.

[0084] A build table assembly according to any of the preceding clauses, wherein the stress ratio between the component and the plurality of fixture segments is equal to or greater than 0.3 and equal to or less than 0.5.

[0085] An additive manufacturing system for producing parts, the additive manufacturing system comprising: a platform; a build table assembly, the build table assembly is arranged on the platform and can rotate relative to the platform around the vertical axis of the build table assembly, the build table assembly comprising: a base, the base having an upper surface; a frame, the frame extending from the upper surface of the base, the frame defining an upper wall; an edge, the edge being formed on the upper wall of the frame; and a plurality of fixture segments, the plurality of fixture segments being positioned on the edge, opposite to the upper wall of the frame, the plurality of fixture segments defining an arcuate build surface, the part being built on the arcuate build surface, the plurality of fixture segments being spaced apart from each other; and a deposition assembly, the deposition assembly having a deposition head, through which molten raw material is deposited onto the plurality of fixture segments.

[0086] An additive manufacturing system according to any of the preceding clauses, wherein each of the plurality of fixture segments comprises: an inner surface; an outer surface opposite the inner surface; an upper surface; a lower surface opposite the upper surface; and a plurality of cavities spaced apart from each other, the plurality of cavities extending through the outer surface and the lower surface.

[0087] A build table assembly according to any of the preceding clauses, wherein the plurality of fixture segments comprises four fixture segments.

[0088] The building table assembly according to any of the preceding clauses further comprises: a plurality of upper nuts, each of which is received in a corresponding cavity among the plurality of cavities; and a plurality of fasteners, the plurality of fasteners fixing each of the plurality of fixture segments to the edge, each of the plurality of fasteners being threadedly engaged with a corresponding upper nut to retain the plurality of fasteners in the corresponding cavity.

[0089] An additive manufacturing system as described in any of the preceding clauses, wherein each cavity has a rounded shape.

[0090] The additive manufacturing system of any of the preceding clauses, wherein each fastener of the plurality of fasteners extends through a corresponding channel formed in the frame, the channel having a diameter greater than a diameter of the fastener to allow the plurality of fixture segments to move radially outward relative to the frame.

[0091] The additive manufacturing system of any of the preceding clauses, wherein a plurality of recesses are formed in the outer surface of the frame and define a plurality of fins, each fastener of the plurality of fasteners terminating within a corresponding recess of the plurality of recesses.

[0092] The additive manufacturing system of any of the preceding clauses, wherein a stress ratio between the component and the plurality of fixture segments is less than 1.0, and is defined by:

[0093]

[0094] Where S_p represents the stress accumulated in the tangential part of the component, YS fixture represents the yield stress of the fixture segment, YS fastener represents the yield stress of the plurality of fasteners, and YS upper_nut represents the yield stress of the upper nut.

[0095] The additive manufacturing system of any of the preceding clauses, wherein the stress ratio between the component and the plurality of fixture segments is equal to or greater than 0.2 and equal to or less than 0.8.

[0096] The additive manufacturing system of any of the preceding clauses, wherein the stress ratio between the component and the plurality of fixture segments is equal to or greater than 0.3 and equal to or less than 0.5.

[0097] A build table assembly for supporting a part, the build table assembly comprising: a frame; and a plurality of fixture segments disposed on the frame, the plurality of fixture segments defining an arcuate build surface on which the part is built, the plurality of fixture segments being spaced apart from one another, wherein a stress ratio between the part and the plurality of fixture segments is less than 1.0, and is defined by:

[0098]

[0099] Where S_p represents the stress accumulated in the tangential part of the component, YS fixture represents the yield stress of the fixture segment, YS fastener represents the yield stress of the plurality of fasteners, and YS upper_nut Represents the yield stress of the upper nut.

[0100] A build table assembly according to any of the preceding clauses, wherein the stress ratio between the component and the plurality of fixture segments is equal to or greater than 0.2 and equal to or less than 0.8.

[0101] A build table assembly according to any of the preceding clauses, wherein the stress ratio between the component and the plurality of fixture segments is equal to or greater than 0.3 and equal to or less than 0.5.

Claims

1. A building table assembly for supporting a component, characterized in that: The construction platform assembly includes: a base having an upper surface; a frame extending from the upper surface of the base, the frame defining an upper wall; a rim formed on the upper wall of the frame; and A plurality of fixture segments are positioned on the rim opposite the upper wall of the frame, the plurality of fixture segments defining an arcuate building surface on which the component is built, the plurality of fixture segments being spaced apart from one another.

2. The construction platform assembly according to claim 1, characterized in that: wherein each fixture segment of the plurality of fixture segments comprises: Inner surface; an outer surface opposite the inner surface; upper surface; a lower surface opposite to the upper surface; and A plurality of cavities are spaced apart from one another and extend through the outer surface and the lower surface.

3. The construction platform assembly according to claim 2, characterized in that: Wherein the plurality of fixture segments comprises four fixture segments.

4. The construction platform assembly according to claim 2, wherein: Further including: a plurality of upper nuts, each upper nut of the plurality of upper nuts being received in a corresponding cavity of the plurality of cavities; and A plurality of fasteners secure each of the plurality of fixture segments to the rim, each of the plurality of fasteners threadingly engaging a corresponding upper nut to retain the plurality of fasteners within the corresponding cavity.

5. The construction platform assembly according to claim 3, characterized in that: Each of the cavities has a rounded shape.

6. The construction platform assembly according to claim 3, characterized in that: Each fastener of the plurality of fasteners extends through a corresponding channel formed in the frame, the channel having a diameter greater than a diameter of the fastener to allow the plurality of fixture segments to move radially outward relative to the frame.

7. The construction platform assembly according to claim 6, wherein: A plurality of recesses are formed in the outer surface of the frame and define a plurality of fins, each of the plurality of fasteners terminating within a corresponding recess of the plurality of recesses.

8. The construction platform assembly according to claim 1, wherein: wherein a stress ratio between the component and the plurality of fixture segments is less than 1.0 and is defined by: Where S_p represents the stress accumulated in the tangential part of the component, YS fixture represents the yield stress of the fixture segment, YS fastener represents the yield stress of the plurality of fasteners, and YS upper_nut represents the yield stress of the upper nut.

9. The construction platform assembly according to claim 8, characterized in that: wherein the stress ratio between the component and the plurality of fixture segments is equal to or greater than 0.2 and equal to or less than 0.

8.

10. The construction platform assembly according to claim 8, wherein: wherein the stress ratio between the component and the plurality of fixture segments is equal to or greater than 0.3 and equal to or less than 0.5.

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