Honing method and machine tool for contour honing

Abstract

In the case of a honing method for machining the internal face (214) of a bore (210) in a workpiece (200) with the aid of at least one honing operation, during a honing operation a flaring-capable honing tool (150) that is coupled to a spindle is moved back and forth within the bore for generating a reciprocating movement in the axial direction of the bore, and are simultaneously rotated for generating a rotating movement that superimposes the reciprocating movement. A bore shape having an axial contour profile which is rotationally symmetrical in terms of a bore axis (212) and deviates from the circular cylindrical shape is generated herein. For generating an axially variable material removal in at least one stroke modification phase a stroke length and/or a stroke orientation of the reciprocating movement is modified. A honing tool (150) which has an annular cutting group (155) having a plurality of radially actuatable cutting material members (156) that are distributed about the circumference of the tool body (152) is used herein. The honing method is distinguished in that during the stroke modification phase a measurement of the actual diameter of the bore (210) is carried out for determining a diameter measurement signal which represents the actual diameter of the bore in a measurement plane, and the stroke length and/or the stroke orientation of the reciprocating movement is controlled as a function of the diameter measurement signal. Also described is a machine tool that is suitable for carrying out the honing method. The honing method is particularly suitable for honing cylinder running faces in the production of cylinder blocks or cylinder liners for reciprocating piston engines.

1 . A honing method for machining the internal face of a bore in a workpiece with the aid of at least one honing operation, in particular for honing cylinder running faces in the production of cylinder blocks or cylinder liners for reciprocating piston engines, wherein during a honing operation a flaring-capable honing tool that is coupled to a spindle is moved back and forth within the bore for generating a reciprocating movement in the axial direction of the bore, and is simultaneously rotated for generating a rotating movement that superimposes the reciprocating movement;
 a bore shape having an axial contour profile, which is rotationally symmetrical in terms of a bore axis and deviates from the circular cylindrical shape, is generated; and   for generating an axially variable material removal in at least one stroke modification phase a stroke length and/or a stroke orientation of the reciprocating movement is modified;   wherein a honing tool which has an annular cutting group having a plurality of radially actuatable cutting material members that are distributed about the circumference of a tool body is used,   wherein during the stroke modification phase a measurement of the actual diameter of the bore is carried out for determining a diameter measurement signal which represents the actual diameter of the bore in a measurement plane; and   the stroke length and/or the stroke orientation of the reciprocating movement is controlled as a function of the diameter measurement signal.   
     
     
         2 . The honing method as claimed in  claim 1 , wherein the reciprocating movement comprises a multiplicity of successive strokes which run in each case between a lower reversal point and an upper reversal point, and in that the axial position of at least one of the reversal points of a stroke is dynamically modified as a function of a diameter measurement signal that is determined in a preceding stroke;
 wherein the axial position of one of the reversal points is preferably fixed and only the axial position of the other reversal point is dynamically varied as a function of the diameter measurement signal;
 wherein the axial contour profile has in particular a portion in which the nominal diameter continuously increases between a first axial position having a smallest diameter within the portion, and a second axial position having a largest diameter within the portion, wherein the reversal point associated with the second axial position is fixed and the axial position of the other reversal point is dynamically varied as a function of the diameter measurement signal. 
   
     
     
         3 . The honing method as claimed in  claim 1 , wherein prior to the honing operation an axial nominal contour profile which represents a nominal diameter as a function of the axial stroke position is predefined, in that in a stroke the actual diameter measured at a stroke position is compared with the nominal diameter associated with the stroke position, and a diameter deviation for the stroke position is determined from the comparison, and in that the stroke length and/or the stroke orientation of a subsequent stroke in relation to a nominal stroke length and/or a nominal stroke orientation is modified as a function of the diameter deviation;
 wherein the stroke length and/or the stroke orientation of the reciprocating movement is preferably modified as a function of the determined diameter deviation in such a manner that the diameter deviation at the axial position is at least in part compensated for by modifying the number of overlapping honing actions at the axial position.   
     
     
         4 . The honing method as claimed in  claim 3 , wherein a reduction in the number of overlapping honing actions at an axial position is generated by modifying the stroke length and/or the stroke orientation of the reciprocating movement when the diameter deviation results in an actual diameter that is too large in comparison to the nominal diameter, and in that an increase in the number of overlapping honing actions at an axial position is generated by modifying the stroke length and/or the stroke orientation of the reciprocating movement when the diameter deviation results in an actual diameter that is too small in comparison to the nominal diameter. 
     
     
         5 . The honing method as claimed in  claim 1 , wherein in the diameter measurement for determining a diameter measurement signal a measured value detection takes place by way of a floating mean value, in particular by way of an adjustable quantity of measuring points, wherein the floating mean value is determined in a portion of the bore or across the entire currently machined portion of the bore. 
     
     
         6 . The honing method as claimed in  claim 1 , wherein the measurement of the actual diameter is carried out when the honing tool is situated in the region of a reversal point of the reciprocating movement;
 wherein the diameter measurement is preferably carried out such that the honing tool during the diameter measurement rotates in an axially narrow measurement zone in the region of a reversal point, wherein a plurality of diameter measurement values are within the narrow measurement zone detected, and averaging across the plurality of diameter measurement values detected in short succession takes place in order for the diameter measurement value to be determined.   
     
     
         7 . The honing method as claimed in  claim 3 , wherein the diameter measurement signals utilized for the nominal/actual comparison and/or for forming the mean value are detected in an intermediate region between the reversal points, in particular in a central region between the reversal points. 
     
     
         8 . The honing method as claimed in  claim 1 , characterized by a continuous actuation of cutting material members of the honing tool during the stroke modification phase, in particular at a constant or pulsed actuation rate. 
     
     
         9 . The honing method as claimed in  claim 1 , characterized by controlling the contact pressure force of cutting material members of the honing tool that is transmitted to the honing tool in a manner that the contact pressure force remains substantially constant during the stroke modification phase. 
     
     
         10 . The honing method as claimed in  claim 1 , wherein the honing tool has at least one of the following properties:
 (i) the axial length of the cutting material members is less than 50% of the effective external diameter of the cutting group, in particular between 10% and 30% of said external diameter;   (ii) the axial length of the cutting material members is in the range from 5 mm to 90 mm;   (iii) the axial length of the cutting material members is less than 35% of the bore length of the bore;   (iv) the cutting material members are configured as cutting material strips that are narrow in the circumferential direction, the width of said cutting material members measured in the circumferential direction being small in relation to the axial length of the cutting material strips, wherein an aspect ratio between the length and the width is preferably in the range from 4:1 to 20:1;   (v) measuring sensors of a diameter measurement system, in particular measuring nozzles of a pneumatic diameter measurement system, are attached in the axial region of the cutting material members, in particular at half the height of the axial length of the cutting material members.   
     
     
         11 . The honing method as claimed in  claim 1 , wherein a honing tool with double flaring is used, wherein the cutting group has two sub-groups of cutting material members which are actuatable in a mutually separate manner, wherein the cutting material members of the sub-groups preferably have grit sizes of dissimilar fineness or coarseness. 
     
     
         12 . The honing method as claimed in  claim 1 , wherein a honing tool in which the cutting group has a plurality of radially actuatable cutting material member supports which cover in each case one circumferential angle range is used, said circumferential angle range being greater than the axial length of the cutting material members, wherein each of the cutting material member supports preferably supports two, three, four, or more, individual cutting material members in the form of narrow honing strips. 
     
     
         13 . The honing method as claimed in  claim 1 , wherein a honing tool is used which for guiding the honing tool in the bore has non-cutting guide strips, wherein the guide strips are fixedly assembled on the tool body, or are actuatable separately from the cutting material members. 
     
     
         14 . A machine tool for the precision machining of an internal face of a bore in a workpiece with the aid of at least one honing operation, in particular for honing cylinder running faces in the production of cylinder blocks or cylinder liners for reciprocating piston engines, having
 at least one spindle for moving a honing tool coupled to the spindle in such a manner within the bore that machining of the internal face takes place by at least one of the cutting material members attached to the honing tool,   wherein the machine tool is configured for carrying out on the workpiece a honing method as claimed in  claim 1 .   
     
     
         15 . The machine tool as claimed in  claim 15 , wherein a control installation of the machine tool is specified for processing diameter measurement signals of a diameter measurement system and for controlling a reciprocating drive of the spindle as a function of the diameter measurement signals.