Systems and methods for powder bed density measurement and control for additive manufacturing

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.

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; and   measuring a density of the powder material within the powder print bed.   
     
     
         2 . The method of  claim 1 , further comprising:
 adjusting a parameter of the printing system based on the measured density of the metal powder material within the powder print bed.   
     
     
         3 . The method of  claim 1 , further comprising:
 comparing the density of the metal powder material to a predetermined criteria.   
     
     
         4 . The method of  claim 2 , 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.   
     
     
         5 . The method of  claim 2 , 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; and   depositing the amount of binder material on the second amount of metal powder material.   
     
     
         6 . The method of  claim 2 , 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.   
     
     
         7 . The method of  claim 1 , wherein measuring the density of the metal powder material within the powder print bed includes determining a weight of the metal powder material within the powder print bed. 
     
     
         8 . The method of  claim 7 , wherein measuring the density of the metal powder material within the powder print bed further includes determining a volume of the metal powder material within the powder print bed. 
     
     
         9 . The method of  claim 1 , wherein measuring the density of the metal powder material within the powder print bed includes:
 measuring at least one of a capacitance or an inductance of the metal powder material within the powder print bed.   
     
     
         10 . The method of  claim 9  wherein the step of measuring at least one of a capacitance or an inductance includes traversing a linear array of sensors over the powder print bed. 
     
     
         11 . The method of  claim 9  wherein during the step of measuring at least one of a capacitance or an inductance, measuring a permeability of the metal powder and a lift-off of a sensor from the metal powder within the powder print bed. 
     
     
         12 . The method of  claim 1 , wherein measuring the density of the metal powder material within the powder print bed includes:
 applying heat to the metal powder material within the powder print bed; and   determining a rate of temperature change of the metal powder material within the powder print bed.   
     
     
         13 . The method of  claim 2 , wherein adjusting the parameter of the printing system includes:
 depositing a second amount of metal powder material onto the first layer;   determining a rotational speed for a spreading roller based on the density of metal powder in the first layer; and   controlling the roller to spread the second amount of metal powder material across the powder print bed to form a second layer.   
     
     
         14 . The method of  claim 1  further comprising comparing the measured density of the metal powder material to at least one predetermined criteria; and
 based on the comparison, identifying a part as non-conforming. 
 
     
     
         15 . The method of  claim 1  further comprising comparing the measured density of the metal powder material to at least one predetermined criteria; and
 based on the comparison, stopping the printing process. 
 
     
     
         16 . 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; 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.   
     
     
         17 . The system of  claim 16 , 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. 
     
     
         18 . The system of  claim 16 , further comprising:
 a print head configured to deposit an amount of binder material to at least one region of the layer; and   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.   
     
     
         19 . The system of  claim 18 , 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.   
     
     
         20 . The system of  claim 16 , 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. 
     
     
         21 . The system of  claim 16 , 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. 
     
     
         22 . The system of  claim 21 , 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. 
     
     
         23 . The system of  claim 16 , 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. 
     
     
         24 . The system of  claim 16 , 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.   
     
     
         25 . The system of  claim 24 , 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.