US-12623287-B2 - Systems and methods for powder bed density measurement and control for additive manufacturing

US12623287B2US 12623287 B2US12623287 B2US 12623287B2US-12623287-B2

Abstract

Systems and methods are disclosed for forming a three-dimensional object using additive manufacturing. One method includes depositing a first amount of powder material onto a powder print bed of a printing system, spreading the first amount of powder material across the powder print bed to form a first layer, measuring a density of powder material within the powder print bed, and adjusting a parameter of the printing system based on the measured density of the powder material within the powder print bed.

Inventors

George Hudelson
Paul Hoisington
Richard Remo Fontana
Emanuel Sachs
Christopher Anthony Craven
Matthew McCAMBRIDGE

Assignees

ARC IMPACT ACQUISITION CORPORATION

Dates

Publication Date: 20260512
Application Date: 20240205

Claims (14)

1 . A method of forming a three-dimensional object using additive manufacturing, the method comprising: depositing a first amount of metal powder material onto a powder print bed of a printing system; spreading the first amount of metal powder material across the powder print bed to form a first layer; measuring a density of the powder material within the powder print bed; and adjusting a parameter of the printing system based on the measured density of the metal powder material within the powder print bed, wherein adjusting the parameter of the printing system includes: determining an amount of binder material to be deposited on a second layer based on the measured density of the metal powder material within the powder print bed; depositing a second amount of metal powder material onto the first layer; depositing the amount of binder material on the second amount of metal powder material.
2 . The method of claim 1 , further comprising: comparing the density of the metal powder material to a predetermined criteria.
3 . The method of claim 1 , wherein adjusting the parameter of the printing system includes: determining a second amount of metal powder material to be deposited onto the powder print bed based on the measured density of the metal powder material within the powder print bed; depositing the second amount of metal powder material onto the powder print; and spreading the second amount of metal powder material across the powder print bed to form a second layer.
4 . The method of claim 1 , wherein adjusting the parameter of the printing system includes: determining an amount of steam to administer to the second layer based on the measured density of the metal powder material within the powder print bed; and applying the determined amount of steam to the second layer.
5 . An additive manufacturing system for forming a three-dimensional object, the system comprising: a hopper configured to deposit powder material onto a powder print bed; a spreader configured to spread the deposited powder material to form a layer; a powder density measuring apparatus configured to measure a density of one or more accumulated powder material layers on the powder print bed; a controller configured to adjust a parameter of the system based on the measured density of the one or more accumulated powder material layers; and a print head configured to deposit an amount of binder material to at least one region of the layer, wherein the controller is configured to control the amount of binder material based on the measured density of the one or more accumulated powder material layers on the powder print bed.
6 . The system of claim 5 , wherein the powder density measuring apparatus includes a sensor configured to determine a height of the deposited powder material, and wherein the controller is configured to control a speed at which to spread the deposited powder material based on the determined height of the deposited amount of powder material.
7 . The system of claim 5 , wherein the print head is further configured to apply an amount of steam to the layer, and wherein the controller is configured to control the amount of steam based on the measured density of the one or more accumulated powder material layers on the powder print bed.
8 . The system of claim 5 , further comprising an acoustic wave generator operably coupled to the controller, wherein the acoustic wave generator is configured to generate one or more acoustic waves based on the measured density of the one or more accumulated powder material layers on the powder print bed.
9 . The system of claim 5 , wherein the powder density measuring apparatus is configured to determine a weight of the one or more accumulated powder material layers on the powder print bed.
10 . The system of claim 9 , wherein the powder density measuring apparatus is further configured to determine a volume of the one or more accumulated powder material layers on the powder print bed.
11 . The system of claim 5 , wherein the powder density measuring apparatus is configured to measure at least one of an inductance or a capacitance of the one or more accumulated powder material layers on the powder print bed.
12 . The system of claim 5 , wherein the powder density measuring apparatus includes: one or more heaters configured to apply heat to the one or more accumulated powder material layers on the powder print bed; and a temperature sensor.
13 . The system of claim 12 , wherein the controller is configured to determine the density of the one or more accumulated powder material layers based on a rate of change in temperature detected by the temperature sensor.
14 . An additive manufacturing system for forming a three-dimensional object, the system comprising: a hopper configured to deposit powder material onto a powder print bed; a spreader configured to spread the deposited powder material to form a layer; a powder density measuring apparatus configured to measure a density of one or more accumulated powder material layers on the powder print bed, wherein the powder density measuring apparatus is further configured to measure at least one of an inductance or a capacitance of the one or more accumulated powder material layers on the powder print bed; and a controller configured to adjust a parameter of the system based on the measured density of the one or more accumulated powder material layers.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a Divisional of U.S. patent application Ser. No. 17/370,845 filed Jul. 8, 2021 and claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 62/872,544 filed Jul. 9, 2020, all of which are herein incorporated by reference in their entirety. TECHNICAL FIELD Various aspects of the present disclosure relate generally to systems and methods for measuring and controlling powder bed density. BACKGROUND OF THE DISCLOSURE Powder bed three-dimensional fabrication is an additive manufacturing technique based on binding particles of a powder to form a three-dimensional object within the powder bed. Binder jetting is one type of powder bed three-dimensional fabrication. Binder jetting includes delivering powder, e.g., metal powder, to a print bed, spreading the powder into a layer, and depositing a binder material, e.g., a binder fluid, on top of the powder to bind the powder together. In some instances, each layer of powder may have a height of about 50-100 μm. The binder material is deposited in a pre-determined pattern (e.g., in a two-dimensional pattern or image that represents a single, cross-sectional shape, or “slice,” of the three-dimensional object) to successive layers of powder in a powder bed such that the powder particles bind to one another where the binder material is located to form a three-dimensional green part. In the context of binder jet printing of three-dimensional metal objects, a three-dimensional green part may be formed by printing as described above, and may then be processed further into a finished three-dimensional metal part. For example, excess, unbound metal powder may be removed from the powder bed. Then, the three-dimensional green part may be heated in a furnace to remove the binder material or to sinter the part to bind the particles together to form the final, three-dimensional part. The three-dimensional green part may be sintered to densify the part to full density (i.e. to remove void spaces within the part) or to lightly bond the particles without substantial removal of void space. For example, during sintering, the part may shrink by 10-30%. It is desirable to have the powder in the powder bed filled to a high density (i.e., tighter packing of the powder particles) as this may facilitate a higher green density of the part, resulting in lower shrinkage of the part during the sintering process as there would be less void space to remove in the green part during densification. Moreover, higher density packing of the powder particles in the print bed may lead to better mechanical interlocking of particles within the green part, which may allow for use of lower sintering temperatures and may reduce slumping (i.e., deformation due to gravity) during the sintering process. There is also a need for the powder bed and green part to have a more uniform density to allow for more uniform part shrinkage and to reduce warping of the part during the sintering process. Variation in density in the green part may result in non-uniform shrinkage during the sintering process, which may cause parts to warp or crack, or may cause variation in the resulting dimensions of parts, leading to dimensional inaccuracy. While the powder density of green parts is critical in sintering-based applications such as binder jetting, the same considerations are typically not as important for melting-based additive manufacturing operations. For example, during Laser Powder Bed Fusion, the powder is melted and solidifies to nearly full density during the process, so the powder density has no or minimal impact on final part density and properties. There are currently a variety of ways to evaluate variability in the powder bed. However, the conventional methods may be either destructive to the powder bed or take longer than desired to obtain a result. For example, one method is to lay down a powder bed and then press a sharp-edged tool such as a thin-walled tube into a column of powder to “cookie-cutter” a volume of powder. The surrounding powder is removed, and the volume of powder contained within the tool is collected and weighed. Density is calculated by dividing the mass of the collected powder by the volume of the captured powder, i.e. the area inside the tube x the powder column height. The captured powder may also be examined by a particle size analyzer to determine if the particle size distribution (PSD) is different in one region of the powder bed from another. A limitation of this method is that it may damage the powder bed and therefore cannot be used as a quality assurance tool when printing. Also, spatial resolution is limited by the size of the coring tool and how closely the cores may be taken, as the act of pressing a coring tool into the powder disturbs the surrounding powder. Another method currently used to evaluate powder bed density is to print parts, cure the binder, and de-powder to obtain the parts in the “brown” s