Sintered body production method, degreased body production method, and heating furnace

Abstract

A sintered body production method includes a first step in which temperature elevation is started based on a first temperature elevation program in a firing furnace in a state where a molded body containing a metal powder and an organic binder is placed in the firing furnace, a second step in which a vacuum degree or a dew point in the firing furnace is measured in the course of elevating the temperature, and a third step in which temperature elevation is performed by applying a second temperature elevation program in place of the first temperature elevation program when the vacuum degree or the dew point measured in the second step does not satisfy a predetermined condition, and temperature elevation is performed by applying the first temperature elevation program when the vacuum degree or the dew point measured in the second step satisfies the predetermined condition.

What is claimed is: 
     
         1 . A sintered body production method, which is a method for producing a sintered body by firing a molded body containing a metal powder and an organic binder, comprising:
 a first step in which temperature elevation is started based on a first temperature elevation program in a firing furnace in a state where the molded body is placed in the firing furnace;   a second step in which a vacuum degree or a dew point in the firing furnace is measured in the course of elevating the temperature; and   a third step in which temperature elevation is performed by applying a second temperature elevation program in place of the first temperature elevation program when the vacuum degree or the dew point measured in the second step does not satisfy a predetermined condition, and temperature elevation is performed by applying the first temperature elevation program when the vacuum degree or the dew point measured in the second step satisfies the predetermined condition.   
     
     
         2 . The sintered body production method according to  claim 1 , wherein the second temperature elevation program is a program in which a temperature elevation rate is increased among the factors constituting the first temperature elevation program. 
     
     
         3 . The sintered body production method according to  claim 2 , wherein the second step is performed again after the third step. 
     
     
         4 . The sintered body production method according to  claim 1 , wherein
 in the second step, the time integral of the vacuum degree or the time integral of the dew point in the firing furnace is calculated, and   the predetermined condition in the third step is a condition associated with the time integral of the vacuum degree or a condition associated with the time integral of the dew point.   
     
     
         5 . A degreased body production method, which is a method for producing a degreased body by degreasing a molded body containing a metal powder and an organic binder, comprising:
 a first step in which temperature elevation is started based on a first temperature elevation program in a degreasing furnace in a state where the molded body is placed in the degreasing furnace;   a second step in which the concentration of a decomposed gas of the organic binder in the degreasing furnace is measured in the course of elevating the temperature; and   a third step in which temperature elevation is performed by applying a second temperature elevation program when the concentration of the decomposed gas measured is within a predetermined range, and temperature elevation is performed by applying the first temperature elevation program when the concentration of the decomposed gas measured is outside the predetermined range.   
     
     
         6 . A heating furnace, comprising:
 a furnace main body;   a heating unit which heats the inside of the furnace main body;   an output adjustment unit which adjusts the output of the heating unit;   a measurement unit which measures a vacuum degree or a dew point in the furnace main body; and   a control unit which has a function of controlling the operation of the output adjustment unit based on a temperature elevation program and a function of rewriting the temperature elevation program based on the measurement result of the measurement unit.   
     
     
         7 . A heating furnace, comprising:
 a furnace main body;   a heating unit which heats the inside of the furnace main body;   an output adjustment unit which adjusts the output of the heating unit;   a measurement unit which measures the concentration of a decomposed gas of an organic binder in the furnace main body; and   a control unit which has a function of controlling the operation of the output adjustment unit based on a temperature elevation program and a function of rewriting the temperature elevation program based on the measurement result of the measurement unit.