Method for production of a sintered component

Abstract

The invention relates to a method for production of a sintered component ( 2 ), comprising the steps: making available an iron-based powder having chromium; filling the powder into a powder press; pressing the powder to form a green compact; sintering the green compact to form the sintered component ( 2 ); post-compacting the sintered component ( 2 ); hardening the sintered component ( 2 ). Sintering is carried out in a decarburizing atmosphere, and the sintered component ( 2 ) is moved, for surface-compacting, along an axis ( 3 ), from a first matrix opening ( 6 ) in the direction of a second matrix opening ( 13 ) of a matrix tool ( 1 ), which opening lies opposite the first matrix opening ( 6 ) along the axis ( 3 ), wherein the sintered component ( 2 ) passes through multiple matrix sections ( 7 - 11 ) of the matrix tool ( 1 ) during this movement, and, in this regard, a surface region of the sintered component ( 2 ) is compacted, for which purpose an inside diameter ( 17 ) of the matrix sections ( 7 - 11 ) that follow one another becomes smaller in the pressing direction, and the individual matrix sections ( 7 - 11 ) are disposed in such a manner that a subsequent matrix section ( 7 - 11 ) of the multiple matrix sections ( 7 - 11 ) directly follows the corresponding preceding matrix section ( 7 - 11 ), in each instance, in the pressing direction.

1 : A method for the production of a sintered component ( 2 ), comprising the steps:
 providing an iron-based powder having chromium;   filling the powder into a powder press;   pressing the powder to form a green compact;   removing the green compact from the powder press;   sintering the green compact to form the sintered component ( 2 );   post-compacting the sintered component ( 2 );   hardening the sintered component ( 2 );   
       wherein sintering is carried out in a decarburizing atmosphere, and wherein the sintered component ( 2 ) is moved, for surface-compacting, along an axis ( 3 ), from a first matrix opening ( 6 ) in the direction of a second matrix opening ( 13 ) of a matrix tool ( 1 ), which second opening lies opposite the first matrix opening ( 6 ) along the axis ( 3 ), wherein the sintered component ( 2 ) passes through multiple matrix sections ( 7 - 11 ) of the matrix tool ( 1 ) during this movement, and, in this regard, a surface region of the sintered component ( 2 ) is compacted, for which purpose an inside diameter ( 17 ) of the matrix sections ( 7 - 11 ) that follow one another becomes smaller in the pressing direction, and the individual matrix sections ( 7 - 11 ) are disposed in such a manner that a subsequent matrix section ( 7 - 11 ) of the multiple matrix sections ( 7 - 11 ) directly follows the corresponding preceding matrix section ( 7 - 11 ), in each instance, in the pressing direction. 
     
     
         2 : The method according to  claim 1 , wherein at least one gas from a group consisting of oxygen, carbon dioxide, hydrogen is contained in the decarburizing atmosphere, wherein the proportion of the gas amounts to between 0.1 vol.-% and 10 vol.-% of the atmosphere. 
     
     
         3 : The method according to  claim 1 , wherein the C proportion in the sintering green compact is reduced by maximally 0.6 wt.-%. 
     
     
         4 : The method according to  claim 1 , wherein after surface-compacting in the last matrix section ( 11 ) having a decreasing inside diameter ( 17 ), relaxing of the sintered component ( 2 ) is carried out in a stress-relief section ( 21 ) that directly follows the last matrix section ( 11 ), which stress-relief section ( 21 ) has a greater inside diameter ( 22 ) in comparison with the last matrix section ( 11 ) configured directly ahead of it of the matrix section ( 7 - 11 ) having a decreasing inside diameter ( 17 ), wherein the sintered component ( 2 ) is calibrated in the stress-relief section ( 21 ), for which purpose the inner contour of this stress-relief section ( 21 ) corresponds to the reference contour having a reference dimension of the sintered component ( 2 ). 
     
     
         5 : The method according to  claim 1 , wherein the chromium proportion of the powder amounts to between 0.1 wt.-% and 10 wt.-%. 
     
     
         6 : The method according to  claim 1 , wherein hardening takes place by means of carburizing and subsequent quenching or sinter-hardening and subsequent quenching or inductive hardening. 
     
     
         7 : The method according to  claim 6 , wherein carburizing is carried out by means of low-pressure carburizing. 
     
     
         8 : The method according to  claim 6 , wherein quenching is carried out using a gas.