Powder supply device and powder supply method

Abstract

In a rapid load reduction mode for reducing a flow rate of powder to be supplied to the outside of a feed tank to a predetermined rate after a predetermined period of time, a controller sets an internal pressure control valve to an exhaust state and closes a powder discharge valve to a predetermined aperture, and as soon as the powder flow rate becomes smaller than a scheduled powder flow rate that is expected before elapse of the predetermined period of time, the controller controls at least one of the internal pressure control valve and the powder discharge valve so that the powder flow rate becomes the scheduled powder flow rate.

1 . A powder supply device that supplies powder in a feed tank to the outside of the feed tank through a powder delivery pipe connected to the feed tank, the device comprising:
 an internal pressure control valve that is connected to the feed tank and that adjusts pressure in the feed tank;   a powder discharge valve that is connected to the powder delivery pipe; and   a controller that controls the internal pressure control valve and the powder discharge valve, wherein:   in a rapid load reduction mode for reducing a flow rate of powder to be supplied to the outside of the feed tank to a predetermined rate after a predetermined period of time, the controller sets the internal pressure control valve to an exhaust state of reducing the pressure in the feed tank and closes the powder discharge valve to a predetermined aperture so that the powder flow rate becomes smaller than the predetermined rate after the predetermined period of time; and   as soon as the powder flow rate becomes smaller than a scheduled powder flow rate that is expected before elapse of the predetermined period of time for reducing the powder flow rate to the predetermined rate after the predetermined period of time, the controller controls at least one of the internal pressure control valve and the powder discharge valve on the basis of information of the powder flow rate so that the powder flow rate becomes the scheduled powder flow rate.   
     
     
         2 . The powder supply device according to  claim 1 , wherein the scheduled powder flow rate is determined based on the powder flow rate that is just before the rapid load reduction mode is set. 
     
     
         3 . The powder supply device according to  claim 1 , wherein:
 the powder delivery pipe has a powder flowmeter connected thereto; and   as soon as the powder flow rate becomes smaller than the scheduled powder flow rate, the controller controls the internal pressure control valve and the powder discharge valve on the basis of information from the powder flowmeter.   
     
     
         4 . The powder supply device according to  claim 1 , wherein the controller sets the internal pressure control valve to the exhaust state before the powder discharge valve is closed to the predetermined aperture. 
     
     
         5 . A powder supply method for supplying powder in a feed tank to the outside of the feed tank through a powder delivery pipe connected to the feed tank, the method comprising:
 in a rapid load reduction mode for reducing a flow rate of powder to be supplied to the outside of the feed tank to a predetermined rate after a predetermined period of time, setting an internal pressure control valve connected to the feed tank to an exhaust state of reducing pressure in the feed tank and closing a powder discharge valve connected to the powder delivery pipe to a predetermined aperture so that the powder flow rate becomes smaller than the predetermined rate after the predetermined period of time; and   as soon as the powder flow rate becomes smaller than a scheduled powder flow rate that is expected before elapse of the predetermined period of time for reducing the powder flow rate to the predetermined rate after the predetermined period of time, adjusting at least one of the internal pressure control valve and the powder discharge valve on the basis of information of the powder flow rate so that the powder flow rate becomes the scheduled powder flow rate.   
     
     
         6 . The powder supply method according to  claim 5 , wherein the scheduled powder flow rate is determined based on the powder flow rate that is just before the rapid load reduction mode is set. 
     
     
         7 . The powder supply method according to  claim 5 , wherein as soon as the powder flow rate becomes smaller than the scheduled powder flow rate, the internal pressure control valve and the powder discharge valve are adjusted based on information from a powder flowmeter connected to the powder delivery pipe. 
     
     
         8 . The powder supply method according to  claim 5 , wherein the internal pressure control valve is set to the exhaust state before the powder discharge valve is closed to the predetermined aperture.