Method for finely processing a cylindrical inner surface

Abstract

The invention relates to a process for precision-machining a cylindrical inner surface, in particular a cylinder bearing surface, which has material of different hardnesses in the axial direction. The cylindrical inner surface is subjected to a precision-turning step, a preliminary honing step and a precision-honing step. The process is distinguished by the fact that the preliminary honing step produces a cone ( 11 ) in the cylindrical inner surface, in such a way that the cone ( 11 ) widens out from a harder region ( 4 ) toward a softer region ( 6 ). In the subsequent precision-honing step, the cone ( 11 ) is compensated for again in the harder region ( 4 ) to produce a cylindrical inner surface, whereas the cone ( 11 ) is retained in the softer region ( 6 ). This prevents the fine abrasive particles on the precision-honing stone from becoming clogged as a result of contact with the softer region.

1 . A process for precision-machining a cylindrical inner surface, in particular a cylinder bearing surface, comprising: 
 subjecting the cylindrical inner surface to at least one preliminary honing step and a precision-honing step, wherein    the cylinder bearing surface has material of different hardnesses in the axial direction,    the preliminary honing step produces a cone ( 11 ) in the cylindrical inner surface, in such a way in that cone ( 11 ) widens out from a harder region ( 4 ) toward a softer region ( 6 ), and    in the subsequent precision-honing step, the cone ( 11 ) is compensated for again in the harder region ( 4 ) to produce a cylindrical inner surface, while the cone ( 11 ) is retained in the softer region ( 6 ).    
   
   
       2 . The process as claimed in  claim 1 , wherein the cone ( 11 ) of the cylindrical inner surface is produced by a honing stone ( 8 ) which runs conically with respect to the said inner surface.  
   
   
       3 . The process as claimed in  claim 1 , wherein the cone ( 11 ) is produced by adjusting the honing parameters.  
   
   
       4 . The process as claimed in  claim 3 , wherein the cone ( 11 ) is produced by adjusting the advance (V) of a honing tool ( 7 ′) in the axial direction ( 9 ) and/or by adjusting the contact pressure (P) of the honing tool ( 7 ′) against the cylindrical inner surface.  
   
   
       5 . The process as claimed in  claim 1 , wherein a honing tool ( 18 ) is used with different types of honing stones ( 20 ,  22 ) which are deployed selectively for the preliminary honing step or precision-honing step or which are deployed selectively for different regions ( 4 ,  6 ) of the cylindrical inner surface.  
   
   
       6 . The process as claimed in  claim 1 , wherein the cone ( 11 ) is introduced over a length ( 10 ) of from 20 mm to 200 mm in the axial direction ( 9 ), and a change ( 12 ) in the radius of the cylindrical inner surface of from 10 μm to 100 μm is established over this region.  
   
   
       7 . The process as claimed in  claim 1 , wherein a second, opposite cone ( 30 ) is introduced into the softer region ( 6 ), so that a convex shape ( 28 ) is established in the softer region ( 6 ).