Patent Application
20210178472
The present specification generally relates to additive manufacturing apparatuses and, more specifically, to additive manufacturing apparatuses with powder storage vessels and methods for using the same.
Additive manufacturing apparatuses may be utilized to “build” an object from build material, such as organic or inorganic powders, in a layer-wise manner. Early iterations of additive manufacturing apparatuses were used for prototyping three-dimensional objects. While there is an increased interest in utilizing additive manufacturing apparatuses for large-scale commercial production of objects, there continues to be a need for smaller additive manufacturing apparatuses for prototyping.
Powder material is typically supplied to the additive manufacturing apparatuses using a hopper or other powder storage vessel. The hopper may store the powder material and also control release of the powder material from the hopper. A need exists for powder storage vessels that provide increased control of release of the powder material within the additive manufacturing apparatuses.
In a first embodiment, an additive manufacturing apparatus for forming a three-dimensional article through successive fusion of parts of layers of a powder material, which parts correspond to successive cross-sections of the three-dimensional article is provided. The additive manufacturing apparatus includes a process chamber housing with a process chamber. An energy beam source is arranged for at least one of heating or fusing a powder material located on a build platform within the process chamber in a predetermined pattern layer-by-layer to form the three-dimensional article. A powder storage vessel is in the process chamber. The powder storage vessel includes a vessel body including a powder storage volume, a floor including a powder delivery opening extending therethrough and a bottom cap including a powder delivery opening extending therethrough. In an open configuration, the powder delivery opening of the bottom cap is aligned with the powder delivery opening of the floor to allow powder material to flow from the powder storage vessel through the powder delivery openings. In a closed configuration, one or both of the vessel body and the bottom cap is rotated relative to the other to misalign the powder delivery openings and inhibit powder material from flowing from the powder storage vessel through the powder delivery openings.
In another embodiment, a powder storage vessel for an additive manufacturing apparatus includes a vessel body including a powder storage volume, a floor having a powder delivery opening extending therethrough and a bottom cap having a powder delivery opening extending therethrough. In an open configuration, the powder delivery opening of the bottom cap is aligned with the powder delivery opening of the floor to allow powder material from the powder storage volume to flow through the powder delivery openings. In a closed configuration, one or both of the vessel body and the bottom cap is rotated relative to the other to misalign the powder delivery openings and inhibit powder material from flowing from the powder storage volume through the powder delivery openings.
In another embodiment, a method of delivering powder material to a build platform of an additive manufacturing apparatus is provided. The method includes placing a powder storage vessel into a process chamber of the additive manufacturing apparatus. The powder storage vessel includes a vessel body including a powder storage volume, a floor having a powder delivery opening extending therethrough and a bottom cap having a powder delivery opening extending therethrough. In an open configuration, the powder delivery opening of the bottom cap is aligned with the powder delivery opening of the floor to allow powder material to flow from the powder storage volume through the powder delivery openings. In a closed configuration, one or both of the vessel body and the bottom cap is rotated relative to the other to misalign the powder delivery openings and inhibit powder material from flowing from the powder storage volume through the powder delivery openings. One or both of the vessel body and the bottom cap is rotated relative to the other thereby moving the powder storage vessel from the closed configuration to the open configuration.
Additional features and advantages of the additive manufacturing apparatuses described herein, and the components thereof, will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.
Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. One embodiment of an additive manufacturing apparatus includes separable process chamber housing portions in order to provide greater access to within the process chambers for cleaning and other operations where access to within the process chamber is needed. Another embodiment of an additive manufacturing apparatus includes a powder storage vessel having a closed configuration where metal powder is inhibited from leaving the powder storage vessel and an open configuration where metal powder is allowed to leave the powder storage vessel. Various embodiments of additive manufacturing apparatuses, additive manufacturing apparatuses including the separable process chambers and/or the powder storage vessels, and methods for using the same are described in further detail herein with specific reference to the appended drawings.
Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
Directional terms as used herein—for example up, down, right, left, front, back, top, bottom, upper, lower,—are made only with reference to the figures as drawn and are not intended to imply absolute orientation unless otherwise expressly stated.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.
As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.
Reference will now be made in detail to embodiments of additive manufacturing apparatuses, and components thereof, examples of which are illustrated in the accompanying drawings. The additive manufacturing apparatuses may include a process chamber housing that houses a build platform onto which a powder material is delivered and an electron beam source that is used to fuse powder together layer-by-layer. A powder storage vessel is provided in the process chamber that can be delivered to the build platform to dispense the powder material thereon. A rotatable support conveyor may be used to both hold the powder storage vessel and also to move the powder storage vessel toward and away from the build platform as layers of fused powder material are being formed.
As can be appreciated, powder material may build up in and may need to be cleaned from the process chamber from time-to-time. To facilitate access to the process chamber for cleaning or any other reason, the process chamber housing is divided into process chamber housing portions including a first process chamber housing portion and a second process chamber housing portion, where the first and second process chamber housing portions are separable from one another to provide increased access to within the process chamber.
As used herein, the term “three-dimensional structures” and the like refer generally to intended or actually fabricated three-dimensional configurations (e.g., of structural material or materials) that are intended to be used for a particular purpose. Such structures may be, for example, designed with the aid of a computer aided design (CAD) program.
As used herein, the term “two-dimensional structures” and the like refer generally to layers of the three-dimensional structure that when built, one over the other, form the three-dimensional structures. While referred to as “two-dimensional structures,” it should be understood that each layer includes an accompanying thickness in a third dimension, albeit the structures have a relatively planar configuration compared to a fused stack of the two-dimensional structures that form the three-dimensional structures.
As used herein, the term “electron beam” refers to any charged particle beam. The sources of a charged particle beam can include an electron gun, a linear actuator, etc.
Various embodiments of the additive manufacturing apparatuses relate to methods for producing three-dimensional objects by layering two-dimensional structures one on the other by powder additive manufacturing, such as using electron beam melting (EBM), selective laser sintering (SLS) and/or selective laser melting (SLM).
Referring to
An electron beam gun 22 generates an electron beam that is used for melting or fusing together powder material provided on a build platform 24. A control unit 26 is provided for controlling and managing the electron beam gun 22 and the electron beam that is emitted. The control unit 26 may include a processor and memory for storing a CAD program and CAD design that can be executed by the processor. A focusing coil, deflection coil, astigmatic coil and an electron beam power supply (all represented by element 28) may be electrically connected to the control unit 26. In some embodiments, the electron beam gun 22 generates a focusable electron beam with an accelerating voltage of between about 15 kV and 120 kV and with a beam power of between about three Kw and about 10 kW. The pressure in the process chamber may be about 1×10−3 mbar or lower when building the three-dimensional structure by fusing the powder layer-by-layer with the electron beam.
In another embodiment, a laser beam may be used for melting or fusing the powder material. In such a case, tiltable mirrors may be used in the beam path in order to deflect the laser beam to a predetermined position. As used herein, a laser beam, electron beam or any other energy suitable in building a three-dimensional structure as discussed herein may be referred to as an energy beam.
A powder storage vessel 30 houses the powder material to be provided on the build platform 24. The powder material may be, for example, pure metals or metal alloys, such as titanium, titanium alloys, aluminum, aluminum alloys, stainless steel, Co—Cr alloys, nickel based super alloys, etc. Additional details of the powder storage vessel are described below.
A powder distributor 29 is arranged to rake a thin layer of powder material that falls from the powder storage vessel 30 onto the build platform 24. During a work cycle, the build platform 24 is lowered successively in relation to a fixed point in the process chamber 14. In order to make this movement possible, the build platform 24 can translate in a vertical direction, i.e., in the direction indicated by arrow P. This means that the build platform 24 starts in an initial position, in which a first powder material layer of necessary thickness is laid down. An actuation system 32 is provided that lowers and then raises the build platform 24. The actuation system 32 may, for example, include any suitable linear actuator.
The energy beam may be directed over the build platform 24 causing a first powder layer to fuse in selected locations to form a first cross-section of the three-dimensional structure. The energy beam is directed over the build platform 24 in accordance with instructions given by the control unit 26. In the control unit 26, instructions for how to control the electron beam for each layer of the three-dimensional structure is stored in memory.
After a first layer is finished, i.e., the fusion of powder material for making a first layer of the three-dimensional structure, a second powder layer is provided on the build platform 24. The second powder layer is distributed according to the same manner as the previous layer in some embodiments. However, there may be other methods in the same additive manufacturing machine for distributing powder onto the build platform 24.
After having distributed the second powder layer on the build platform 24, the energy beam is directed over the build platform 24 causing the second powder layer to fuse in selected locations to form a second cross section of the three-dimensional article. Fused portions in the second layer may be bonded to fused portions of the first layer. The fused portions in the first and second layer may be melted together by melting not only the powder in the uppermost layer but also re-melting at least a fraction of a thickness of a layer directly below the uppermost layer.
In some embodiments, a shield 36 (e.g., formed of stainless steel) may be provided between the build platform 24 and the powder storage vessel 30. The shield 36 may inhibit heated metal powders from sputtering into the process chamber 14.
A rotatable support conveyor 40 may be used to both hold the powder storage vessel 30 and also to move the powder storage vessel 30 toward and away from the build platform 24 as layers of fused powder material are being formed. A motor 42 may be provided that is used to rotate the rotatable support conveyor 40 based on instructions from the control unit 26. After each layer of material is formed, the control unit 26 instructs the motor 42 to rotate the rotatable support conveyor 40, which moves both the powder storage vessel 30 and the powder distributor 29 that is underneath the powder storage vessel 30 toward the build platform 24. At onset of an additive manufacturing process, the build platform 24 may be below a floor 44 of the process chamber housing 12 a predetermined amount (e.g., about 20-100 μm per layer). This allows a layer of powder material of a predetermined thickness to be raked over the build platform 24. The rotatable support conveyor 40 then returns the powder storage vessel 30 to its initial position while the electron beam gun 22 fuses the powder material in a predetermined pattern.
The layer of powder material provided on the build platform 24 may have a working diameter of about 100 mm or less. The build platform 24 may move down in the direction P a total distance of about 100 mm or less thereby capable of building a 100 mm×100 mm×100 mm three-dimensional structure. In this regard, the additive manufacturing apparatus 10 may be referred to as compact. As used herein, the term “compact additive manufacturing apparatus” refers to additive manufacturing apparatuses having a working area (i.e., area of the build platform 24) of no greater than about 785 cm2 for a working area having a diameter of 100 mm. While the work area is shown as circular herein, the work area may be any suitable shape, such as rectangular, irregular, or any other suitable shape. In some embodiments, the compact additive manufacturing apparatuses may be defined by the size of the process chamber, which may be no greater than about 31400 cm3.
Because the size of additive manufacturing apparatus 10 may be relatively small, the additive manufacturing apparatus may be provided with separable process chamber housing portions, such as a first separable process chamber housing portion 52 and a second separable process chamber housing portion 54. The process chamber housing 12 may be separable so that an operated does not have to rely on presence of an openable door of limited area to enter into the process chamber 14, for example, for a cleaning operation or to exchange components, such as the powder storage vessel 30. An actuation device 56 is connected to one or both of the first and second separable process chamber housing portions 52 and 54. The actuation device 56 may include a first linear actuator 58 and a second linear actuator 60 on a side of the process chamber housing 12 that is opposite the first linear actuator 58. The first linear actuator 58 includes a first housing connection 62 that is connected to the first process chamber housing portion 52 and a second housing connection 64 that is connected to the second process chamber housing portion 54. Likewise, the second linear actuator 60 includes a first housing connection 66 that is connected to the first process chamber housing portion 52 and a second housing connection 68 that is connected to the second process chamber housing portion 54. Additional details of the separable process chamber housing portions 52 and 54 are described in greater detail below.
Referring to
The floor 74 has a pair of powder delivery openings 90 and 92 (see
The bottom cap 80 can rotate relative to the vessel body 70 to place the powder storage vessel 30 in the open configuration or the closed configuration. Referring particularly to
Referring again to
Referring now to
As shown most clearly by
The cavity structure 110 further includes tab receiving recesses 144 and 146. The tab receiving recesses 144 and 146 are located on opposite sides of the cavity structure 110 and are oriented about 90 degrees offset from the clip portions 136. As can be seen in
Referring briefly to
Referring to
As noted above, the size of the process chamber housing 12 may be relatively small. Because of this, it may be difficult to access all areas of the process chamber 14 through an access opening 160 provided at a front of the process chamber housing 12. For example, the access opening 160 may have a height/width/diameter that is less than about 500 mm, such as less than about 250 mm, such as less than about 200 mm, such as less than about 175 mm, such as less than about 150 mm. A door 162 may be provided that closes the access opening 160. The door 162 may include a latch 164 that allows for latching and unlatching the door 162 to the process chamber housing 12. An average human hand breadth where the fingers meet the palm may be about 80 mm for illustrative purposes. It can be appreciated that reaching into the process chamber 14 through the access opening 160 may be somewhat cumbersome.
The process chamber housing 12 includes the first separable process chamber housing portion 52 and the second separable process chamber housing portion 54. The first separable process chamber housing portion 52 includes a top 164 of the process chamber housing 12 and at least a portion of a side 166 of the process chamber housing 12. The second separable process chamber housing portion 54 includes a bottom 168 of the process chamber housing 12 and may include a portion of the side 166 of the process chamber housing 12. The first separable process chamber housing portion 52 meets the second separable process chamber housing portion 54 at a junction 170. The junction 170 is formed between a first flange 172 at a terminal end of the first separable process chamber housing portion 52 and a second flange 174 at a terminal end of the second separable process chamber housing portion 54. A seal 176 (e.g., an O-ring seal) may be provided within a recess 178 between the first and second flanges 172 and 174. The seal 176 may be provided to help maintain an air-tight environment within the process chamber 14 through the junction 170 with the process chamber housing 12 in a closed configuration, as shown by
Referring to
In some embodiments, the first linear actuator 58 and the second linear actuator 60 may be gas springs. A gas spring is a type of spring that uses compressed gas contained within an enclosed cylinder sealed by a sliding piston to pneumatically store potential energy. For example, a pull-type gas spring may be used that holds the process chamber housing 12 in the closed configuration. When a tension above a predetermined level is applied to the first linear actuator 58 and the second linear actuator 60, the rods 184, 186, 196, 198 are forced to move relative to the cylinders 180, 182, 192, 194, and the gas spring assists the operator in placing the process chamber housing 12 in the open configuration. Further, the gas springs can hold the process chamber housing 12 in the open configuration until a compressive force of a predetermined amount is applied to the first linear actuator 58 and the second linear actuator 60.
It can be appreciated that providing a separable process chamber housing 12 with the first separable process chamber housing portion 52 and the second separable process chamber housing portion 54 increases access area with the process chamber housing 12 in the open configuration compared to the closed configuration. Further, because many of the components discussed above, such as the powder storage vessel 30, rotatable support conveyor 40, build platform 24 and shield 36 travel with the second separable process chamber housing portion 54 and out of the first separable process chamber housing portion 52, added access is provided to those components. In some embodiments, the first and second linear actuators 58 and 60 may be operated automatically, e.g., using the control unit 26. For example, the first and second linear actuator 58 and 60 may be pneumatic cylinders or be motor-operated. In some embodiments, the linear actuators 58 and 60 may be sized to separate the first and second separable process chamber housing portions a distance D of at least about 80 mm, such as a distance of at least about 100 mm, such as a distance of at least about 150 mm, such as a distance of at least about 200 mm, such as a distance of at least about 250 mm, such as a distance of at least about 300 mm. In some embodiments, the distance D may be about a height of the process chamber 14 or more.
Referring to
After a three-dimensional structure is built, as described above, it may be desirable to clean or otherwise access the process chamber 14. At step 220, an operator may grasp one or both of the first and second separable process chamber housing portions 52 and 54 and pull one away from the other providing a tensioning force to the first linear actuator 58 and the second linear actuator 60. The tensioning force may cause the process chamber housing 12 to move into the open configuration at step 222. The first and second separable process chamber housing portions 52 and 54 may then be held in the open configuration until a compressive force is applied to the first linear actuator 58 and the second linear actuator 60 thereby causing the process chamber housing to move into the closed configuration.
The above-described additive manufacturing apparatuses include powder storage vessels that can be used to control egress of the powder material stored therein from their powder storage volumes. The powder storage vessels have a closed configuration where powder is inhibited from leaving the powder storage vessels and an open configuration where powder is allowed to leave the powder storage vessels.
Further aspects of the invention are provided by the subject matter of the following clauses:
1. An additive manufacturing apparatus for forming a three-dimensional article through successive fusion of parts of layers of a powder material, which parts correspond to successive cross-sections of the three-dimensional article, the additive manufacturing apparatus comprising: a process chamber housing with a process chamber; an energy beam source arranged for at least one of heating or fusing a powder material located on a build platform within the process chamber in a predetermined pattern layer-by-layer to form the three-dimensional article; and a powder storage vessel in the process chamber, the powder storage vessel comprising: a vessel body comprising a powder storage volume; a floor comprising a powder delivery opening extending therethrough; and a bottom cap comprising a powder delivery opening extending therethrough; wherein, in an open configuration, the powder delivery opening of the bottom cap is aligned with the powder delivery opening of the floor to allow powder material to flow from the powder storage vessel through the powder delivery openings; and wherein, in a closed configuration, one or both of the vessel body and the bottom cap is rotated relative to the other to misalign the powder delivery openings and inhibit powder material from flowing from the powder storage vessel through the powder delivery openings.
2. The additive manufacturing apparatus of any preceding clause, wherein the bottom cap further comprises a guide pin received within a guide opening formed through the floor of the vessel body.
3. The additive manufacturing apparatus of any preceding clause, wherein the vessel body comprises a sidewall having an access opening extending therethrough, the access opening providing access to the guide pin from outside the vessel body.
4. The additive manufacturing apparatus of any preceding clause, wherein the guide pin is threaded to receive a lock member.
5. The additive manufacturing apparatus of any preceding clause, wherein the vessel body comprises a sidewall and a pair of guide walls that extend downward toward the floor adjacent to opposite sides of the powder delivery opening.
6. The additive manufacturing apparatus of any preceding clause, wherein the powder delivery opening of the floor is a first powder delivery opening of the floor, the floor further comprising a second powder delivery opening.
7. The additive manufacturing apparatus of any preceding clause, wherein the powder delivery opening of the bottom cap is a first powder delivery opening of the bottom cap, the bottom cap further comprising a second powder delivery opening.
8. The additive manufacturing apparatus of any preceding clause, wherein, in the open configuration, the first and second powder delivery openings of the bottom cap are aligned with the respective first and second powder delivery openings of the floor to allow powder material to flow from the powder storage vessel through the first and second powder delivery openings of the bottom cap, wherein, in the closed configuration, one or both of the vessel body and the bottom cap is rotated relative to the other to misalign the first and second powder delivery openings of the bottom cap and the floor and inhibit powder material from flowing from the powder storage vessel through the first and second powder delivery openings of the bottom cap.
9. The additive manufacturing apparatus of any preceding clause, wherein the vessel body comprises a dowel rod extending therethrough, wherein ends of the dowel rod are received by clips on opposite sides of the vessel body located within the process chamber.
10. The additive manufacturing apparatus of any preceding clause, wherein the bottom cap comprises a tab that is received within a tab receiving recess thereby inhibiting rotation of the bottom cap as the vessel body rotates while locating the ends of the dowel rod in the clips.
11. A powder storage vessel for an additive manufacturing apparatus, the powder storage vessel comprising: a vessel body comprising a powder storage volume; a floor having a powder delivery opening extending therethrough; and a bottom cap having a powder delivery opening extending therethrough; wherein, in an open configuration, the powder delivery opening of the bottom cap is aligned with the powder delivery opening of the floor to allow powder material from the powder storage volume to flow through the powder delivery openings, wherein, in a closed configuration, one or both of the vessel body and the bottom cap is rotated relative to the other to misalign the powder delivery openings and inhibit powder material from flowing from the powder storage volume through the powder delivery openings.
12. The powder storage vessel of any preceding clause, wherein the bottom cap further comprises a guide pin received within a guide opening formed through the floor of the vessel body.
13. The powder storage vessel of any preceding clause, wherein the vessel body comprises a sidewall having an access opening extending therethrough, the access opening providing access to the guide pin from outside the vessel body.
14. The powder storage vessel of any preceding clause, wherein the guide pin is threaded to receive a lock member.
15. The powder storage vessel of any preceding clause, wherein the vessel body comprises a sidewall and a pair of guide walls that extend downward toward the floor adjacent to opposite sides of the powder delivery opening.
16. The powder storage vessel of any preceding clause, wherein the powder delivery opening of the floor is a first powder delivery opening of the floor, the floor further comprising a second powder delivery opening.
17. The powder storage vessel of any preceding clause, wherein the powder delivery opening of the bottom cap is a first powder delivery opening of the bottom cap, the bottom cap further comprising a second powder delivery opening.
18. The powder storage vessel of any preceding clause, wherein, in the open configuration, the first and second powder delivery openings of the bottom cap are aligned with the respective first and second powder delivery openings of the floor to allow powder material to flow from the powder storage vessel through the first and second powder delivery openings of the bottom cap, wherein, in the closed configuration, one or both of the vessel body and the bottom cap is rotated relative to the other to misalign the first and second powder delivery openings of the bottom cap and the floor and inhibit powder material from flowing from the powder storage vessel through the first and second powder delivery openings of the bottom cap.
19. A method of delivering powder material to a build platform of an additive manufacturing apparatus, the method comprising: placing a powder storage vessel into a process chamber of the additive manufacturing apparatus, the powder storage vessel comprising: a vessel body comprising a powder storage volume; a floor having a powder delivery opening extending therethrough; and a bottom cap having a powder delivery opening extending therethrough; wherein, in an open configuration, the powder delivery opening of the bottom cap is aligned with the powder delivery opening of the floor to allow powder material to flow from the powder storage volume through the powder delivery openings, wherein, in a closed configuration, one or both of the vessel body and the bottom cap is rotated relative to the other to misalign the powder delivery openings and inhibit powder material from flowing from the powder storage volume through the powder delivery openings; and rotating one or both of the vessel body and the bottom cap relative to the other thereby moving the powder storage vessel from the closed configuration to the open configuration.
20. The method of any preceding clause, wherein the step of rotating includes rotating the vessel body until ends of a dowel rod are received by clips on opposite sides of the vessel body located within the process chamber.
It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.
