Screw powder feeders
AssigneeQuantum Laser Corporation
InventorsWilliam M. Steen, Vijitha M. Weerasinghe
Life of this patent
Estimating the term…
Abstract
A screw powder feeder has a rotary screw (12) disposed at the base of a hopper (10). The screw (12) comprises a twist drill bit. Powder is discharged into a chamber (18) and picked-up by a flow of gas. The pressure in chamber (18) is varied relative to the pressure in hopper (10) to control the feed rate for a given screw speed. Ultra-low feed rates are made possible by feeding gas into the hopper (10) through the screw (12) and controlling the relative gas pressures such that the pressure in the chamber (18) exceeds the pressure in hopper (10).
Claims17
A screw powder feeder, comprising:
- (a) a first chamber for receiving a supply of powder and including a first gas inlet and a first gas/powder outlet;
- (b) a second chamber having a second gas inlet, a second gas/powder outlet and a first gas/powder inlet communicating with said first gas/powder outlet;
- (c) screw conveyor means positioned within said first chamber in alignment with said first gas/powder outlet and including a longitudinal body mounted for rotation on a longitudinal axis thereof and having a central longitudinal bore, at least two helical flutes disposed in said body and defining a pair of threads and a plurality of apertures disposed in said threads and longitudinally spaced along said body and communicating with said bore;
- (d) means operably associated with said conveyor means for rotating said body;
- (e) means operably associated with said bore for supplying a first pressurized gas thereto so that the gas exits said apertures and thereby permits powder to be transported by said rotating body through said first gas/powder outlet and into said second chamber;
- (f) second means operably associated with said gas inlets for supplying a second pressurized gas thereto;
- and,
- (g) at least a portion of said flutes being provided with outwarding projecting means for directing powder into said flutes.
A powder feeder for fine cohesive powders, comprising:
- (a) a gravity feed hopper having a first inlet at one end thereof and a first outlet in a sidewall thereof;
- (b) a chamber operably associated with said hopper and having a second inlet at one end thereof, a second outlet at an opposite end thereof and a third inlet in a sidewall thereof in communication with said first outlet;
- (c) gas supply means operably associated with said first and second inlets for supplying a pressurizing gas thereto;
- (d) screw means journaled within said hopper in alignment with said first outlet and third inlet for transporting a powder from said hopper to said chamber so that the powder will exit therefrom through said second outlet;
- (e) at least two helical flutes disposed in said screw means and defining a pair of threads, each thread having a trailing edge and a leading edge and means extending from one of said edges for displacing powder in said chamber into said threads;
- (f) a bore extending longitudinally through said screw means and including means at one end thereof for connection with a source of pressurized gas;
- (g) a plurality of apertures disposed in said threads and communicating with said bore so that pressurizing gas will exit said apertures and permit powder to flow by breaking up static arch formation in the powder above said screw means;
- and,
- (h) means for rotating said screw means.
Dependencies are inferred from the claim text.