POWDER BED RE-COATER APPARATUS AND METHODS OF USE THEREOF

Abstract

The present disclosure relates to systems, methods, and apparatuses for supplying powder to a powder bed during an additive manufacturing process. A recoater apparatus includes a powder reservoir and a powder distribution system for conveying powder from the powder reservoir to the powder bed. The recoater apparatus further includes at least two sweep strips, wherein at least one exit of the powder distribution system is located between the two sweep strips so as to shield the exit of the powder distribution system.

Claims

1. An apparatus for supplying a powder comprising: a powder reservoir; a first sweep strip; a second sweep strip; and a powder distribution system comprising; an inlet for receiving powder from the reservoir; an outlet for supplying powder received from the inlet, the outlet being located between the first sweep strip and the second sweep strip.

2. The apparatus for supplying a powder of claim 1, wherein the powder distribution system further comprises: a housing portion in fluid communication with the inlet; a roller rotatable around an axis within the housing, the axis extending in a first direction, wherein the roller is configured to convey powder from the inlet.

3. The apparatus for supplying a powder of claim 2, wherein the roller is textured.

4. The apparatus for supplying a powder of claim 2, wherein the roller is a metering roller having a plurality of metering protrusions extending along the first direction.

5. The apparatus for supplying a powder of claim 3, wherein the roller is configured to convey powder to the outlet via a communication path in fluid communication with outlet and the housing portion.

6. The apparatus for supplying a powder of claim 1, further comprising: a first height detector for detecting a height of the apparatus from a powder bed at a first location, wherein the quantity of powder supplied at the outlet is controlled based on an output from the first height detector.

7. The apparatus for supplying a powder of claim 6, further comprising: a second height detector for detecting a height of the apparatus from a powder bed at a second location different from the first location, wherein the quantity of powder supplied at the outlet is controlled based on an output from the first height detector and the second height detector.

8. The apparatus for supplying a powder of claim 4, wherein the powder distribution system further comprises: a powder distribution member having a plurality of openings for supplying powder to the outlet, wherein powder is supplied to the distribution member by the metering roller.

9. The apparatus for supplying a powder of claim 8, wherein the powder distribution member further comprises at least one vibrating member capable of vibrating the powder distribution member.

10. The apparatus for supplying a powder of claim 4, wherein the powder distribution system further includes a fluidizing chamber, wherein powder is supplied to the fluidizing chamber by the metering roller, and the powder is fluidized by a fluidizing gas, wherein the fluidized powder is provided to the outlet between the first and second sweep strips.

11. The apparatus for supplying a powder of claim 10, wherein the fluidizing chamber further comprises: a fluidizing gas inlet; a fluidizing gas outlet; a fluidizing powder device having a plurality of openings and an overflow portion for supplying powder to the outlet, wherein the fluidizing gas is supplied from the fluidizing gas inlet through the plurality of openings, wherein the fluidized powder overflows from the overflow portion to the outlet.

12. The apparatus for supplying a powder of claim 11, wherein the fluidizing powder device further comprises at least one vibrating element, wherein the vibrating element is capable of vibrating the fluidizing powder device.

13. The apparatus of claim 1, wherein the apparatus is configured to provide powder to an additive manufacturing machine during an additive manufacturing process.

14. The apparatus of claim 13, wherein the apparatus provides powder during the additive manufacturing of a component, wherein the apparatus provides powder to at least a portion of component to be solidified, wherein the clearance between at least one of the first sweep strip and the second sweep strip and the component is less than 1 mm.

15. The apparatus of claim 1, wherein the first sweep strip and the second sweep strip extend along a first direction, wherein the first sweep strip further comprises: a top portion connected to the apparatus and a bottom portion further from the apparatus than the top portion, wherein the second sweep strip further comprises: top portion connected to the apparatus and a bottom portion further from the apparatus than the top portion, wherein the bottom portion of one of the first and second sweep strips extends further below the apparatus than the other of the first and second sweep strips.

16. The apparatus of claim 15, wherein the apparatus is configured to travel and supply a layer of powder along at least a first direction, wherein when the first sweep strip is the forward sweep strip in the first direction and the second sweep strip is the aft sweep strip with relation to the first direction, the bottom portion of the first sweep strip extends further below the apparatus than the second sweep strip.

17. The apparatus of claim 15, wherein the apparatus is configured to travel and supply powder along at least a second direction, wherein when the second sweep strip is the forward sweep strip in the second direction and the first sweep strip is the aft sweep strip with relation to the second direction, the bottom portion of the second sweep strip extends further below the apparatus than the first sweep strip.

18. A method for supplying a powder comprising: storing powder in a powder reservoir, conveying the powder from the powder reservoir to a powder outlet located between a first sweep strip and a second sweep strip via a powder distribution system.

19. The method of supplying a powder of claim 18, further comprising: conveying the powder from the powder reservoir to at least one of a powder bed and a fused powder region; setting the sweep strip height of at least one of the sweep strips such that the clearance between the at least one of the powder bed and fused powder region is less than 1 mm.

20. The method of supplying a powder of claim 19, further comprising: conveying the powder from the powder reservoir to supply a layer of powder to the at least one of a powder bed and fused powder region along a first direction; setting the sweep strip height such that the forward most sweep strip along the first direction is offset with respect to the rearward most sweep strip along the first direction, wherein the rearward most sweep strip is offset higher than the forward most sweep strip to compensate for the height of the powder layer provided to the at least one of a powder bed and fused powder region.

21. The method for supplying a powder of claim 20, further comprising: controlling the quantity of powder supplied at the outlet based on a distance between at least one of the first sweep strip and second sweep strip and the at least one of a powder bed and fused region, wherein the distance is determined based on the output from a first height detector.

22. The method for supplying a powder of claim 20, wherein the sweep strip height is adjusted to remove powder from a first portion of the fused region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more example aspects of the present disclosure and, together with the detailed description, serve to explain their principles and implementations.

[0020] FIG. 1 is a conventional additive manufacturing apparatus;

[0021] FIG. 2A is a front view of a conventional, fixed recoater;

[0022] FIG. 2B is a side view of the conventional, fixed recoater shown in FIG. 2A;

[0023] FIG. 2C is a side view of various fixed recoater according to the prior art encounters a hard surface feature.

[0024] FIG. 3A is a cutaway side view of the recoater apparatus in accordance with one aspect of the disclosure;

[0025] FIG. 3B is a perspective view of the metering wheel usable with the recoater apparatus shown in FIG. 3A;

[0026] FIG. 4A is a cutaway side view of the recoater apparatus in accordance with one aspect of the disclosure;

[0027] FIG. 4B is a perspective view of the metering wheel and powder distribution screen usable with the recoater apparatus shown in FIG. 4A;

[0028] FIG. 5A is a cutaway side view of the recoater apparatus in accordance with one aspect of the disclosure;

[0029] FIG. 5B is a perspective view of the metering wheel and powder fluidizing device usable with the recoater apparatus shown in FIG. 5A.

DETAILED DESCRIPTION OF THE INVENTION

[0030] 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.

[0031] In one aspect of the invention, as shown in FIG. 3A, a recoater apparatus 300 is mounted movably mounted to an AM apparatus. The recoater apparatus 300 includes a powder hopper 325 for holding a powder 319 for use in an AM process. The recoater apparatus may be mounted to a track system, and/or rail system, and/or a robotic arm such that the movement of the recoater apparatus 300 can be controlled along the x-axis, y-axis, and/or the z-axis, for example. As shown in FIG. 3A, the recoater apparatus may extend along the y axis and may move across a powder bed 302 in a direction 301 which may be perpendicular to the x-axis. The powder bed 302 may include powder and/or an at least partially fused and/or sintered component being built layer-by-layer as explained in the aforementioned description or any other method known in the art. For example, the present invention may be incorporated or combined with features of any powder bed additive manufacturing methods and systems. The following patent applications are an example of such additive manufacturing methods and systems and their use:

[0032] U.S. patent application Ser. No. 15/406,467, titled Additive Manufacturing Using a Mobile Build Volume, with attorney docket number 037216.00059, and filed Jan. 13, 2017;

[0033] U.S. patent application Ser. No. 15/406,454, titled Additive Manufacturing Using a Mobile Scan Area, with attorney docket number 037216.00060, and filed Jan. 13, 2017;

[0034] U.S. patent application Ser. No. 15/406,444, titled Additive Manufacturing Using a Dynamically Grown Build Envelope, with attorney docket number 037216.00061, and filed Jan. 13, 2017;

[0035] U.S. patent application Ser. No. 15/406,461, titled Additive Manufacturing Using a Selective Recoater, with attorney docket number 037216.00062, and filed Jan. 13, 2017;

[0036] U.S. patent application Ser. No. 15/609,965, titled Apparatus and Method for Continuous Additive Manufacturing, with attorney docket number 037216.00102, and filed May 31, 2017;

[0037] U.S. patent application Ser. No. 15/406,471, titled Large Scale Additive Machine, with attorney docket number 037216.00071, and filed Jan. 13, 2017;

[0038] U.S. patent application Ser. No. 15/406,454, titled Additive Manufacturing Using a Mobile Scan Area, with attorney docket number 037216.00060, and filed Jan. 13, 2017;

[0039] U.S. patent application Ser. No. 15/610,214, titled Method for Real-Time Simultaneous and Calibrated Additive and Subtractive Manufacturing, with attorney docket number 037216.00109, and filed May 31, 2017;

[0040] U.S. patent application Ser. No. 15/609,747, titled Apparatus and Method for Real-Time Simultaneous Additive and Subtractive Manufacturing with Mechanism to Recover Unused Raw Material, with attorney docket number 037216.00110, and filed May 31, 2017.

[0041] The disclosures of the above applications are incorporated herein in their entirety to the extent that they disclose additional aspects of powder bed additive manufacturing methods and systems that can be used in conjunction with those disclosed herein.

[0042] The recoater apparatus 300 shown in FIG. 3A may include a frame 325 extending along the y-axis and having a dimension along the y-axis that is greater than the dimension of the recoater apparatus in the x-axis, for example. The frame may include a hopper 327 for containing a powder 319 to be distributed to the powder bed 302. The frame may further include heaters 308 for preheating the powder 319 in the hopper 327. The frame 325 may also include a powder distribution system 305. The powder distribution system 305 may comprise an axially rotatable textured roller 310, rotatable about an axis 314, and having surface cavities and/or protrusions 312 sized appropriately for the powder 319 being conveyed by the powder distribution system. The frame may include a housing portion 321 which may be cylindrically shaped and correspond with the outer dimensions of the rotatable textured roller 310. Accordingly, the cylindrical housing portion 321 may have a clearance so that an appropriately sized gap exists between the rotatable textured roller 310 and the cylindrical housing portion 321 for conveyance of the powder 319. The rotatable textured roller 310 may be connected to motor (e.g. a stepper motor). Accordingly, powder 319 may be in contact with the roller 310 through passage 322. Thus, when the roller 310 is rotated via the motor, powder is conveyed along the surface of the roller 310 to the powder supply exit 318. Accordingly, powder can be precisely supplied to the powder bed 302 as the recoater apparatus moves in direction 301.

[0043] As mentioned above, the recoater apparatus 300 shown in FIG. 3A may have the advantage compatibility with all traditional powders. Further, the recoater apparatus may be compatible with powders having a larger size distribution than would normally be desired, which has the advantage of decreasing the cost of the powder being used in the apparatus. For example, the roller texture, clearances within the recoater apparatus, and control of the motor may be optimized for compatibility with powders having a greater size distribution. Another advantage of the recoater apparatus configuration is compatibility with very fine powders. The recoater apparatus may be compatible with powders having a very fine size which may not be compatible with traditional recoater systems, which has the advantage of increasing the resolution of the built AM component. For example, the roller texture, clearances within the recoater apparatus, and control of the motor may be optimized for compatibility with fine powders.

[0044] The recoater apparatus may further include an aft sweep strip 306 and a forward sweep strip 307. The sweep strips 306 and 307 may be positioned such that the powder supply exit 318 is located between the sweep strips 306 and 307. Thus, the sweep strips 306 and 307 may function as a shield to block gas flow from interfering with the powder distribution process. The sweep strips may be adjustable along the z-axis either through height (i.e. z-axis) adjustment of the recoater apparatus 300, or the sweep strips may be individually adjustable along the z-axis through an individual adjustment mechanism on each of the forward and aft sweep strips. Further, the height of each of the forward sweep strip 307 and aft sweep strip 306 may be adjustable through tilting of the recoater apparatus in combination with the abovementioned height adjustment of the recoater apparatus 300. As discussed below, the sweep strips may be adjusted using any one of or combination of the aforementioned methods such that the sweep strips do not contact or minimally contact the powder bed while effectively blocking gas flow which may interfere with the powder distribution process. Further, the sweep strip height may be controlled to sweep powder across the powder bed. Each of the sweep strips may be comprised of a soft pliable material (e.g. a foam, silicone, rubber), a rigid or semi rigid material.

[0045] The sweep strips 307 and/or 306 may also be configured to remove a quantity of powder from a build region. For example, while a build process progresses by solidifying powder, a portion of the build may begin to increase in height at a faster rate than another portion of the build. In other words, with reference to FIG. 3A for example, a first portion of the build may extend further in the Z direction than a second portion of the build. Thus, if powder is continuously supplied and fused at the same rate at the first portion and the second portion the dimensions of the completed component may be effected and/or build problems may arise. In order to prevent such problems, as the component is being built, the sweep strips 307 and/or 306 may serve a leveling function by removing and/or limiting the supply of powder to the portion of the build that extends further in the Z direction, by selectively controlling the amount of powder that is supplied to each region (either using the below mentioned methods of supply and/or by removing powder via the sweep strips) a more consistent build may be achieved, and problems such as those discussed in the abovementioned background section may be avoided.

[0046] The recoater apparatus 300 may further include several sensors to assure that powder is precisely metered and distributed along the surface of the powder bed and/or the build component in the powder bed. As an example, the recoater apparatus 300 may include a photo-emitter-receiver pair to sense the consistency and uniformity of powder flow through the passage 322, the powder supply exit 318, and/or within the cylindrical housing portion. It is noted that the abovementioned sensor locations may be used in any combination to determine the amount of powder being supplied to the powder bed. Further, it is noted that a plurality of sensors may be located in each location, for example a plurality of sensors may be located along the y-axis direction to assure detect the amount of powder being supplied along the width of the powder bed along the length of the recoater apparatus 300. The sensors may also include an aft z-height sensor array 316 and a forward z-height sensor array 317 to precisely monitor the height of the recoater apparatus 300 with respect to the powder bed and/or to determine a height difference between the forward z-height sensor 317 and the aft z-height sensor 316 with respect to the powder bed, which may be used to determine the thickness of the layer of powder provided by the recoater apparatus to the powder bed 302. The forward z-height sensor array 317 and the aft z-height sensor array 316 may be capacitive proximity sensors. The forward z-height sensor array 317 and the aft z-height sensor array 316 may also include or be combined with any well-known sensors in the art usable to determine a height in a non-contact manner. The abovementioned forward z-height sensor array 317 and the aft z-height sensor array 316 may be used to adjust the height of the recoater apparatus 300 and/or may be used to adjust the quantity or distribution of powder to be supplied to the powder bed 302 through the powder supply exit 318.

[0047] As discussed above, outputs from the forward z-height sensor array 317, aft z-height sensor array 316, photo-emitter-receiver pair in the passage 322, the photo-emitter-receiver pair in the powder supply exit 318, and/or within the cylindrical housing portion may be processed by a controller to continuously adjust the output to the motor connected to the rotatable textured roller 310. Thus, by controlling the rotation of the textured roller 310 the powder 319 can be precisely distributed along the powder bed 302 and/or build component as the recoater travels in direction 301 across the powder bed 302.

[0048] Based on the output of any of the mentioned sensors, the forward sweep strip 307 and the aft sweep strip 306 may be adjusted such that the a bottom portion of the forward sweep strip 307 that is further from the apparatus than a top portion of the forward sweep strip 307 is offset with relation to the bottom portion of the aft sweep strip 306 (i.e. lower in the z-direction). In other words, because a layer of powder is supplied from the opening to the powder bed and/or component being built in the powder bed, it may be preferable to adjust the aft sweep strip 306 in the z-direction to compensate for the thickness of the layer of powder provided. If the recoater apparatus reverses direction (i.e. causing the aft sweep strip to become the forward sweep strip), it may be necessary to adjust the sweep strip height in a similar manner (i.e. the forward sweep strip lower in the z-direction that the aft sweep strip). Using any of the abovementioned techniques, it may be further preferable to adjust the sweep strip heights such that a clearance in the z-direction between the powder bed and/or build component and the sweep strips is less than 1 mm.

[0049] As shown in FIG. 4A the recoater apparatus 400 may include a frame 426 extending along the y-axis and having a dimension along the y-axis that is greater than the dimension of the recoater apparatus in the x-axis, for example. The frame may include a powder reservoir 427 for containing a powder 419 to be distributed to the powder bed 402. The frame may further include heaters (e.g. similar to heaters 308 shown in FIG. 3A) for preheating the powder 419 in the powder reservoir 427. The reservoir may further include an ultrasonic transducer 326 for controlling the movement of powder within the reservoir 427. Further, the frame 425 may also include a powder distribution system 405. The powder distribution system 405 may comprise an axially rotatable dosing roller 410, rotatable about an axis 414, and having metering blades 412 extending along the axis of the roller and sized appropriately for the powder 419 being conveyed by the powder distribution system. It is noted that as an alternative the metering roller may include channels and/or metering blades that are curved or corkscrew shaped. Further, the metering roller may include surface irregularities and/or cavities and protrusions similar to those shown in FIG. 3B. The frame may include a cylindrical housing portion 421 which corresponds with the outer dimensions of the rotatable metering roller 410. Accordingly, the cylindrical housing portion 421 may have a clearance so that an appropriately sized gap exists between the rotatable metering roller 410 and the cylindrical housing portion 421 for conveyance of the powder 419.

[0050] The rotatable metering roller 410 may be connected to motor (e.g. a stepper motor). Accordingly, powder 419 may be in contact with the roller 310 through passage 422. Thus, when the roller 410 is rotated via the motor, powder is conveyed along the surface of the roller 410 to the powder distribution member 432. As shown in FIG. 4B, the powder distribution member 432 may be trough shaped and include a screen 434 or a series of openings along the bottom surface of the distribution member 432 for allowing powder to fall through. The distribution member 432 may be mounted to the recoater apparatus 400 via rubber mounts 430 or any other mount that allows the screen to be connected to the recoater while still allowing vibration of the distribution member. The distribution member 432 may include a single or a plurality of ultrasonic transducers 436. The single or plurality ultrasonic transducers, along with rotation of the metering wheel can be controlled to precisely supply the powder 419 contained in the powder reservoir 427 to the powder bed 402 as the recoater apparatus moves in direction 401.

[0051] As mentioned above, the recoater apparatus 400 shown in FIG. 4A may have the advantage compatibility with all traditional powders. Further, the recoater apparatus may be compatible with powders having a larger size distribution than would normally be desired, which has the advantage of decreasing the cost of the powder being used in the apparatus. For example, the roller features, clearances within the recoater apparatus, size of the openings in the distribution member, the ultrasonic transducer control, and control of the motor may be optimized for compatibility with powders having a greater size distribution. Another advantage of the recoater apparatus configuration is compatibility with very fine powders. The recoater apparatus may be compatible with powders having a very fine size which may not be compatible with traditional recoater systems, which has the advantage of increasing the resolution of the built AM component. For example, the roller features, clearances within the recoater apparatus, size of the openings in the distribution member, the ultrasonic transducer control, and control of the motor may be optimized for compatibility with fine powders.

[0052] The recoater apparatus may further include an aft sweep strip 406 and a forward sweep strip 407. The sweep strips 406 and 407 may be positioned such that the powder distributed by the distribution member 432 to the powder bed proximal to location 404 is between the sweep strips 406 and 407. Thus, the sweep strips 406 and 407 may function as a shield to block any gas flow from interfering with the powder distribution process. Optionally, the sweep strips may be adjustable along the z-axis either through height (i.e. z-axis) adjustment of the recoater apparatus 400, or the sweep strips may be individually adjustable along the z-axis through an individual adjustment mechanism on each of the forward and aft sweep strips. Further, the height of each of the forward sweep strip 407 and aft sweep strip 406 may be adjustable through tilting of the recoater apparatus 400 in combination with the abovementioned height adjustment of the recoater apparatus 400. As discussed below, the sweep strips may be adjusted using any one of or combination of the aforementioned methods such that the sweep strips do not contact or minimally contact the powder bed while effectively blocking gas flow which may interfere with the powder distribution process. Further, the sweep strip height may be controlled to sweep powder across the powder bed.

[0053] The sweep strips 407 and/or 406 may also be configured to remove a quantity of powder from a build region. For example, while a build process progresses by solidifying powder, a portion of the build may begin to increase in height at a faster rate than another portion of the build. In other words, with reference to FIG. 4A for example, a first portion of the build may extend further in the Z direction than a second portion of the build. Thus, if powder is continuously supplied and fused at the same rate at the first portion and the second portion the dimensions of the completed component may be effected and/or build problems may arise. In order to prevent such problems, as the component is being built, the sweep strips 407 and/or 406 may serve a leveling function by removing and/or limiting the supply of powder to the portion of the build that extends further in the Z direction, by selectively controlling the amount of powder that is supplied to each region (either using the below mentioned methods of supply and/or by removing powder via the sweep strips) a more consistent build may be achieved, and problems such as those discussed in the abovementioned background section may be avoided.

[0054] The recoater apparatus 400 may further include several sensors to assure that powder is precisely metered and distributed along the surface of the powder bed and/or the build component in the powder bed. As an example, the recoater apparatus may include a photo-emitter-receiver pair (not shown) to sense the consistency and uniformity of powder flow through the passage 422, the powder supply exit proximal to location 404, and/or within the cylindrical housing portion 421. It is noted that the abovementioned sensor locations may be used individually or in any combination to determine the amount of powder being supplied to the powder bed. Further, it is noted that a plurality of sensors may be located in each location, for example a plurality of sensors may be located along the y-axis direction to assure detect the amount of powder being supplied along the width of the powder bed along the length of the recoater apparatus 400. The sensors may also include an aft z-height sensor array 416 and a forward z-height sensor array 417 to precisely monitor the height of the recoater apparatus 400 with respect to the powder bed and/or to determine a height difference and/or clearance between the sweep strips 407 and 406 and powder bed at the forward z-height sensor 417 at location 403 and the aft z-height sensor 416 at location 402, which may be used to determine the amount of powder to be provided by the recoater apparatus to the powder bed 402 through control of the metering wheel 410 and the distribution member 432. The forward z-height sensor array 417 and the aft z-height sensor array 416 may be capacitive proximity sensors. The forward z-height sensor array 417 and the aft z-height sensor array 416 may also include or be combined with any well-known sensors in the art usable to determine a height in a non-contact manner. The abovementioned forward z-height sensor array 417 and the aft z-height sensor array 416 may be used to adjust the height of the recoater apparatus 400 and/or may be used to adjust the quantity or distribution of powder to be supplied to the powder bed 402 through the powder supply exit 418.

[0055] As discussed above, outputs from the forward z-height sensor array 417, aft z-height sensor array 416, photo-emitter-receiver pair in the passage 422, the photo-emitter-receiver pair in the powder supply exit 404, and/or within the cylindrical housing portion 421 may be processed by a controller to continuously adjust the output to the motor connected to the rotatable metering roller 410 and/or the ultrasonic transducers on the powder distribution member 432. Thus, by controlling the rotation of the metering roller 410 and/or powder distribution member 432, the powder 419 can be precisely distributed along the powder bed 403 at location 404 and/or at the build component as the recoater travels in direction 401 across the powder bed.

[0056] As shown in FIG. 5A the recoater apparatus 500 may include a frame 526 extending along the y-axis and having a dimension along the y-axis that is greater than the dimension of the recoater apparatus in the x-axis, for example. The frame may include a powder reservoir 527 for containing a powder 519 to be distributed to the powder bed 502. The frame may further include heaters (e.g. similar to heaters 308 shown in FIG. 3A) for preheating the powder 519 in the powder reservoir 527. The frame 525 may also include a powder distribution system 505. The powder distribution system 505 may comprise an axially rotatable dosing roller 510, rotatable about an axis 514, and having metering blades 512 extending along the axis of the roller and sized appropriately for the powder 519 being conveyed by the powder distribution system. It is noted that as an alternative the metering roller may include channels and/or metering blades that are curved or corkscrew shaped. Further, the metering roller may include surface irregularities and/or cavities and protrusions similar to those shown in FIG. 3B. The frame may include a cylindrical housing portion 521 which corresponds with the outer dimensions of the rotatable metering roller 510. Accordingly, the cylindrical housing portion 521 may have a clearance so that an appropriately sized gap exists between the rotatable metering roller 510 and the cylindrical housing portion 521 for conveyance of the powder 519.

[0057] The rotatable metering roller 510 may be connected to motor (e.g. a stepper motor). Accordingly, powder 519 may be in contact with the roller 510 through passage 522. Thus, when the roller 510 is rotated via the motor, powder is conveyed along the surface of the roller 510 to the powder distribution member 538. As shown in FIG. 4B, the powder distribution member 538 may include a fluidizing portion 550. The fluidizing portion 550 may include a fluidized bed portion 534. The fluidized bed portion 534 may be trough shaped and include a bottom portion 545 having a screen and/or mesh portion, for example. As an alternative, or in combination with a screen and/or mesh portion, the bottom portion 545 may have a series or pattern of openings. The fluidizing bed portion may include a guiding angled portion 535 for guiding powder from the metering roller 510 into the fluidizing bed. The fluidizing bed 534 may further include an overflow portion 537 which may be substantially adjacent to an opening 548 for supplying powder to the powder bed 502. The fluidizing portion 550 may include a fluidizing gas inlet 543 and a fluidizing gas outlet 539. A fluidizing gas may be supplied through the fluidizing gas inlet 543 to control the flow of the powder supplied from the rotatable metering roller 510 to the opening 548 by controlling the overflow of powder over the overflow portion 537. The fluidizing gas may exit the fluidizing portion 550 through the fluidizing gas outlet 539. The fluidizing bed and/or the fluidizing member may be mounted to the recoater apparatus 500 via rubber mounts 530 or any other mount that allows the fluidizing bed to be connected to the recoater while still allowing vibration of the distribution member. Further, the fluidizing bed and/or fluidizing portion may include a seal 532 that prevents the fluidizing gas from escaping from the perimeter of the of the fluidizing portion and/or fluidizing bed while allowing vibration of the fluidizing bed. The fluidizing portion 550 and/or the fluidizing bed 534 may include a single or a plurality of ultrasonic transducers 536. The single or plurality ultrasonic transducers 536, along with rotation of the metering roller 510, and the inflow of fluidizing gas through inlet 543 and/or the exit of fluidizing gas through outlet 539 can be controlled to precisely supply the powder 519 contained in the powder reservoir 527 to the powder bed 502 as the recoater apparatus 500 moves across the powder bed.

[0058] As mentioned above, the recoater apparatus 500 shown in FIG. 5A may have the advantage compatibility with all traditional powders. Further, the recoater apparatus may be compatible with powders having a larger size distribution than would normally be desired, which has the advantage of decreasing the cost of the powder being used in the apparatus. For example, the roller features, clearances within the recoater apparatus, the fluidizing portion, the ultrasonic transducer control, and control of the motor may be optimized for compatibility with powders having a greater size distribution. Another advantage of the recoater apparatus configuration is compatibility with very fine powders. The recoater apparatus may be compatible with powders having a very fine size which may not be compatible with traditional recoater systems, which has the advantage of increasing the resolution of the built AM component. For example, the roller features, clearances within the recoater apparatus, size of the openings in the distribution member, the fluidizing portion, the ultrasonic transducer control, and control of the motor may be optimized for compatibility with fine powders.

[0059] The recoater apparatus may further include an aft sweep strip 506 and a forward sweep strip 507. The sweep strips 506 and 507 may be positioned such that the powder distributed by the distribution member 505 to the powder bed proximal to location 540 is between the sweep strips 506 and 507. Thus, the sweep strips 506 and 507 may function as a shield to block gas flow from interfering with the powder distribution process. Optionally, the sweep strips may be adjustable along the z-axis either through height (i.e. z-axis) adjustment of the recoater apparatus 500, or the sweep strips may be individually adjustable along the z-axis through an individual adjustment mechanism on each of the forward and aft sweep strips. Further, the height of each of the forward sweep strip 507 and aft sweep strip 506 may be adjustable through tilting of the recoater apparatus 500 in combination with the abovementioned height adjustment of the recoater apparatus 500. As discussed below, the sweep strips may be adjusted using any one of or combination of the aforementioned methods such that the sweep strips do not contact or minimally contact the powder bed while effectively blocking gas flow which may interfere with the powder distribution process. Further, the sweep strip height may be controlled to sweep powder across the powder bed.

[0060] The recoater apparatus 500 may further include several sensors to assure that powder is precisely metered and distributed along the surface of the powder bed and/or the build component in the powder bed. As an example, the recoater apparatus may include a photo-emitter-receiver pair (not shown) to sense the consistency and uniformity of powder flow through the passage 522, the powder supply exit proximal to location 548, within the fluidizing portion 550, and/or within the cylindrical housing portion 521. It is noted that the abovementioned sensor locations may be used individually or in any combination to determine the amount of powder being supplied to the powder bed. Sensors may also be located at the fluidizing gas inlet and outlet to so that the supply of fluidizing gas may monitored and controlled. Further, it is noted that a plurality of sensors may be located in each of the above-mentioned locations, for example a plurality of sensors may be located along the y-axis direction to assure detect the amount of powder being supplied along the width of the powder bed along the length of the recoater apparatus 500. The sensors may also include an aft z-height sensor array 516 and a forward z-height sensor array 517 to precisely monitor the height of the recoater apparatus 500 with respect to the powder bed and/or to determine a height difference and/or clearance between the sweep strips 507 and 506 and powder bed at the forward z-height sensor 517 at location 503 and the aft z-height sensor 516 at location 502, which may be used to determine the amount of powder to be provided by the recoater apparatus to the powder bed 502 through control of the metering wheel 510 and the distribution member 432. The forward z-height sensor array 517 and the aft z-height sensor array 516 may be capacitive proximity sensors. The forward z-height sensor array 517 and the aft z-height sensor array 516 may also include or be combined with any well-known sensors in the art usable to determine a height in a non-contact manner. The abovementioned forward z-height sensor array 517 and the aft z-height sensor array 516 may be used to adjust the height of the recoater apparatus 500 and/or may be used to adjust the quantity or distribution of powder to be supplied to the powder bed 502 through the powder supply exit 548.

[0061] Based on the output of the abovementioned sensors, the forward sweep strip 507 and the aft sweep strip 506 may be adjusted such that the a bottom portion of the forward sweep strip 507 that is further from the apparatus than a top portion of the forward sweep strip 507 is offset with relation to the bottom portion of the aft sweep strip 506 (i.e. lower in the z-direction). In other words, because a layer of powder is supplied from the opening to the powder bed and/or component being built in the powder bed, it may be preferable to adjust the aft sweep strip 506 in the z-direction to compensate for the thickness of the layer of powder provided. If the recoater apparatus reverses direction (i.e. causing the aft sweep strip to become the forward sweep strip), it may be necessary to adjust the sweep strip height in a similar manner (i.e. the forward sweep strip lower in the z-direction that the aft sweep strip). Using any of the abovementioned techniques, it may be further preferable to adjust the sweep strip heights such that a clearance in the z-direction between the powder bed and/or build component and the sweep strips is less than 1 mm.

[0062] The sweep strips 503 and/or 506 may also be configured to remove a quantity of powder from a build region. For example, while a build process progresses by solidifying powder, a portion of the build may begin to increase in height at a faster rate than another portion of the build. In other words, with reference to FIG. 5B for example, a first portion of the build may extend further in the Z direction than a second portion of the build. Thus, if powder is continuously supplied and fused at the same rate at the first portion and the second portion the dimensions of the completed component may be effected and/or build problems may arise. In order to prevent such problems, as the component is being built, the sweep strips 503 and/or 306 may serve a leveling function by removing and/or limiting the supply of powder to the portion of the build that extends further in the Z direction, by selectively controlling the amount of powder that is supplied to each region (either using the below mentioned methods of supply and/or by removing powder via the sweep strips) a more consistent build may be achieved, and problems such as those discussed in the abovementioned background section may be avoided.

[0063] As discussed above, outputs from the forward z-height sensor array 517, aft z-height sensor array 516, photo-emitter-receiver pair in the passage 522, the photo-emitter-receiver pair in the powder supply exit 504, the fluidizing portion 550, the fluidizing gas inlet 543, the fluidizing gas outlet 539, and/or within the cylindrical housing portion 521 may be processed by a controller to continuously adjust the output to the motor connected to the rotatable metering roller 510, the supply of fluid to the fluidizing gas inlet 543 and/or the fluidizing gas outlet 539, and/or the ultrasonic transducers 536. Thus, by controlling abovementioned variables in powder distribution member 505, the powder 519 can be precisely distributed along the powder bed 502 at location in a vicinity of portion 540 and/or at the build component as the recoater 500 travels across the powder bed 502.

[0064] 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.