Method and apparatus for grinding a workpiece

A grinding method wherein a rotating workpiece and a rotating grinding wheel are relatively moved toward and away from each other and wherein at least first, second and third grinding steps are performed successively at high, medium and low infeed rates respectively for grinding said workpiece, said method comprising the steps of:

• (1) measuring the diameter of said workpiece during said grinding steps;
• (2) detecting the infeed position of said grinding wheel relative to said workpiece during said grinding steps;
• (3) effecting said first grinding step for performing the rough grinding of said workpiece;
• (4) calculating a first amount which is left unground due to the bending of said workpiece, based upon the diameter of said workpiece at the end of said first grinding step and the position of said grinding wheel relative to said workpiece at the end of said first grinding step;
• (5) estimating a second amount which would be left unground at the end of said second grinding step, based upon said first amount and a third amount which has been detected and stored at the end of said third grinding step for a preceding workpiece portion;
• (6) calculating a first back-off position from said first and second amounts at the end of said first grinding step;
• (7) moving said grinding wheel and said workpiece away from each other to locate one of said grinding wheel and said workpiece to said calculated first back-off position;
• (8) effecting said second and third grinding steps in turn;
• and
• (9) calculating said third amount which is left unground due to the bending of said workpiece at the end of said third grinding step, so as to store said calculated third amount for use in estimating said second amount relating to a successive workpiece.

A grinding apparatus wherein a rotating workpiece and a rotating grinding wheel are relatively moved toward and away from each other and wherein at least first and second grinding steps are performed successively at high and low infeed rates respectively for grinding said workpiece, said apparatus comprising:

• measuring means for measuring the diameter of said workpiece during said grinding steps;
• detection means for detecting the infeed position of said grinding wheel relative to said workpiece during said grinding steps;
• feed control means for effecting said first and second grinding steps;
• back-off position calculation means for calculating a back-off position at the end of said first grinding step, based upon relative position of said grinding wheel and said workpiece detected at the end of said first grinding step and the diameter of said workpiece measured at the end of said first grinding step;
• and
• wherein upon completion of said grinding step, said feed control means causes said grinding wheel and said workpiece to move away from each other to locate one of said grinding wheel and said workpiece to said calculated back-off position and then, effects said second grinding step.

A grinding apparatus wherein a rotating workpiece and a rotating grinding wheel are relatively moved toward and away from each other and wherein at least first, second and third grinding steps are performed successively at high, medium and low infeed rates respectively for grinding said workpiece, said apparatus comprising:

• measuring means for measuring the diameter of said workpiece during said grinding steps;
• detection means for detecting the infeed position of said grinding wheel relative to said workpiece during said grinding steps;
• feed control means for effecting said first, second and third grinding steps for performing the grinding of said workpiece;
• first calculation means for calculating a first amount which is left unground due to the bending of said workpiece, based upon the diameter of said workpiece at the end of said first grinding step and the position of said grinding wheel relative to said workpiece at the end of said first grinding step;
• second calculation means for calculating a third amount which is left unground due to the bending of said workpiece at the end of said third grinding step, so as to store said calculated third amount for use in estimating a second amount relating to a successive workpiece;
• prediction means for estimating said second amount which would be left unground at the end of said second grinding step, based upon said first amount and said third amount which has been detected and stored by said second calculation means at the end of said third grinding step for a preceding workpiece portion;
• back-off position calculation means for calculating a first back-off position from said first and second amounts at the end of said first grinding step;
• and
• wherein upon completion of said first grinding step, said feed control means causes said grinding wheel and said workpiece to move away from each other to locate one of said grinding wheel and said workpiece to said calculated first back-off position and then, effects said second and third grinding steps in turn.