Method and apparatus for measuring apparent density of metal powder, method and apparatus for producing mixed powder, and method and apparatus for producing powder compact

Abstract

A method for measuring an apparent density of a metal powder includes holding a metal powder in a vessel, applying an alternating magnetic flux to the metal powder using an exciting coil disposed outside the vessel, detecting the alternating magnetic flux passed through the metal powder using a-search coil disposed outside the vessel, and determining an apparent density of the metal powder from an amplitude of the detected alternating magnetic flux using a calibration curve representing a correlation between the apparent density of the metal powder and the amplitude of an alternating magnetic flux prepared in advance. The method enables to measure the apparent density of a metal powder with a high precision in an on-line and non-contact manner without stopping a process of producing a mixed powder or a process of producing a powder compact.

1 - 10 . (canceled) 
     
     
         11 . A method for producing a mixed powder containing a metal powder using a vessel, the method comprising:
 performing a mixing operation by mixing a metal powder and auxiliary raw materials in a mixer with each other to produce a mixed powder while measuring an apparent density of the mixed powder in the vessel by a method that includes: (i) applying an alternating magnetic flux to the mixed powder using an exciting coil disposed outside the vessel, and (ii) detecting an alternating magnetic flux passed through the mixed powder using a search coil disposed outside the vessel; and   ending the mixing operation when a predetermined apparent density is achieved,   wherein the vessel is disposed outside turns of the exciting coil and turns of the search coil.   
     
     
         12 . A method for producing a powder compact in a powder compact manufacturing line, the method comprising:
 filling a die with a mixed powder containing a metal powder supplied from a vessel; and   compacting the mixed powder,   wherein an apparent density of the mixed powder held in the vessel of the powder compact manufacturing line is measured by a method that includes (i) using the vessel in an on-line manner, (ii) applying an alternating magnetic flux to the mixed powder using an exciting coil disposed outside the vessel, and (iii) detecting an alternating magnetic flux passed through the mixed powder using a search coil disposed outside the vessel,   a filling depth of the mixed powder in the die is adjusted in accordance with the measured apparent density, and   the vessel is disposed outside turns of the exciting coil and turns of the search coil.   
     
     
         13 . The method according to  claim 12 , wherein the vessel includes a feeder box from which the mixed powder is supplied to the die and the apparent density of the mixed powder held in the feeder box is measured by the apparent density of the metal powder or the mixed powder, the method further comprising:
 holding the metal powder or the mixed powder containing a metal powder in a vessel; and   determining an apparent density of the metal powder or the mixed powder from an amplitude of the detected alternating magnetic flux using a calibration curve representing a correlation between the apparent density of the metal powder or the mixed powder and the amplitude of the alternating magnetic flux prepared in advance,   wherein the metal powder or the mixed powder is the mixed powder.   
     
     
         14 . An apparatus for measuring an apparent density of a metal powder or a mixed powder comprising:
 a vessel that holds a metal powder or a mixed powder containing a metal powder;   an exciting coil that applies an alternating magnetic flux to the metal powder or the mixed powder, the exciting coil being disposed outside the vessel;   a search coil that detects the alternating magnetic flux passed through the metal powder or the mixed powder, the search coil being disposed outside the vessel; and   a calculator that calculates an apparent density of the metal powder or the mixed powder from an amplitude of the alternating magnetic flux detected by the search coil using a correlation between the amplitude and the apparent density of the metal powder or the mixed powder derived and stored in advance,   wherein the vessel is disposed outside turns of the exciting coil and turns of the search coil.   
     
     
         15 . The apparatus according to  claim 14 , wherein the metal powder or the mixed powder is the mixed powder. 
     
     
         16 . An apparatus for producing a mixed powder containing a metal powder, the apparatus comprising:
 a mixer;   an exciting coil that applies an alternating magnetic flux to a mixed powder containing a metal powder in the mixer, the exciting coil being disposed outside the mixer;   a search coil that detects the alternating magnetic flux passed through the mixed powder, the search coil being disposed outside the mixer; and   a calculator that calculates an apparent density of the mixed powder by inputting an amplitude of the alternating magnetic flux detected by the search coil,   wherein the mixer is disposed outside turns of the exciting coil and turns of the search coil.   
     
     
         17 . An apparatus for producing a powder compact comprising:
 a die to be filled with a mixed powder containing a metal powder and to compact the mixed powder;   a feeder that supplies the mixed powder to the die;   an exciting coil that applies an alternating magnetic flux to the mixed powder held in the feeder, the exciting coil being disposed outside the feeder;   a search coil that detects the alternating magnetic flux passed through the mixed powder held in the feeder, the search coil being disposed outside the feeder; and   a calculator that calculates an apparent density of the mixed powder by inputting an amplitude of the alternating magnetic flux detected by the search coil,   wherein the feeder is disposed outside turns of the exciting coil and turns of the search coil.   
     
     
         18 . The apparatus according to  claim 17 , wherein:
 the feeder includes a feeder box from which the mixed powder is supplied to the die; and   the exciting coil applies the alternating magnetic flux to the mixed powder held in the feeder box and the search coil detects the alternating magnetic flux passed through the mixed powder held in the feeder box.   
     
     
         19 . A mixed powder manufacturing line comprising:
 a hopper;   a feeder; and   a mixer,   wherein the hopper or the feeder is provided with an apparatus for measuring an apparent density of a metal powder or a mixed powder according to  claim 14 .   
     
     
         20 . A powder compact manufacturing line comprising:
 a hopper;   a feeder;   a mixer; and   a die,   wherein the hopper or the feeder is provided with an apparatus for measuring an apparent density of a metal powder or a mixed powder according to  claim 14 .