Device for metering one or more powders, corresponding metering process and 3d printer that includes the device

A device for metering one or more powders in order to produce a flow of the one or more powders and of a carrier gas at a given volume flow rate, the device comprising:

• at least a first source adapted to supply a first flow including a first powder and a first carrier gas at a volume flow rate substantially equal to the given volume flow rate;
• a source of a carrier gas adapted to supply an adjustment carrier gas flow at a volume flow rate substantially equal to the given volume flow rate;
• an outlet junction for sending the flow of the one or more powders and of carrier gas;
• at least a first proportional valve including an inlet connected to the first source to receive the first flow, a first outlet for selectively sending a volume percentage X1 of the first flow to the outlet junction, and a second outlet adapted to send a volume percentage 100−X1 of the first flow, the percentage X1 being between 0% and 100% inclusive and representative of a setting of the first proportional valve;
• an adjustment proportional valve including an inlet connected to the source of the carrier gas by a first connecting line to receive at least a fraction of the adjustment carrier gas flow, a first outlet adapted to send a volume percentage Y of the fraction, and a second outlet adapted to send a volume percentage 100−Y of the fraction, the percentage Y being between 0% and 100% inclusive and representative of a setting of the adjustment proportional valve;
• and
• a control system adapted to control at least the first proportional valve and the adjustment proportional valve and configured so that the flow of the one or more powders and of carrier gas has a volume flow rate substantially equal to the given volume flow rate.

A method of metering one or more powders for producing a flow of one or more powders and a carrier gas at a given volume flow rate, the method including at least the following steps:

• obtaining from a first source a first flow including a first powder and a first carrier gas at a volume flow rate substantially equal to the given volume flow rate;
• obtaining from a source of a carrier gas a flow of adjustment carrier gas at a volume flow rate substantially equal to the given volume flow rate;
• sending the flow of the one or more powders and carrier gas from an outlet junction;
• receiving the first flow via an inlet of a first proportional valve;
• sending a volume percentage X1 of the first flow to an outlet junction via a first outlet of the first proportional valve;
• sending a volume percentage 100−X1 of the first flow via a second outlet of the first proportional valve, the percentage X1 being between 0% and 100% inclusive and obtained by adjusting the first proportional valve;
• receiving at least a fraction of the adjustment carrier gas flow via an inlet of an adjustment proportional valve, the inlet being connected to the source of the carrier gas via a first connecting line;
• sending a percentage Y of the fraction of the adjustment carrier gas via a first outlet of the adjustment proportional valve;
• sending a percentage 100−Y of the fraction via a second outlet of the adjustment proportional valve, the percentage Y being between 0% and 100% inclusive and obtained by adjustment of the adjustment proportional valve;
• and
• controlling at least the first proportional valve and the adjustment proportional valve by means of a control system configured so that the flow of the one or more powders and carrier gas has a volume flow rate substantially equal to the given volume flow rate.