Grinding machine for bearing rings and method for setting tangency conditions in such a machine

Abstract

A grinding machine for bearing rings includes a frame, a rotating grinding wheel rotationally movable around a first rotation axis, a working station where a bearing ring stands during a surface grinding operation, a chuck for holding a bearing ring, the chuck being rotationally movable around a second rotation axis. The machine includes a first automatic mechanism to set the position of a shaping tool with respect to an outer peripheral edge of the grinding wheel, these first automatic mechanism includes an electric motor, an encoder coupled to the electric motor to detect a rotation of an output shaft of the motor, a sensor of the position of the shaping tool along a translation axis and a comparator to compare output signals from each of the encoder and the sensor. The machine also includes second automatic mechanism to set the axial position of the chuck along the second rotation axis.

1 . A grinding machine for bearing rings, the grinding machine including:
 a frame;   a rotating grinding wheel movable in rotation around a first rotation axis;   a working station where a bearing ring stands during a grinding operation of one of its surfaces;   a chuck for holding a bearing ring in the working station, this chuck being movable in rotation around a second rotation axis;   a first automatic mechanism to set a position of a shaping tool with respect to an outer peripheral edge of the grinding wheel, the first automatic mechanism includes an electric motor, an encoder coupled to the electric motor to detect a rotation of an output shaft of the motor, a sensor of the position of the shaping tool along a translation axis and a comparator to compare an output signal of the encoder and an output signal of the sensor; and   a second automatic mechanism to set the axial position of the chuck along the second rotation axis, these second automatic mechanism including an electric motor for driving the chuck in translation along the second rotation axis and a sensor to detect a rotation of the chuck around the second rotation axis.   
     
     
         2 . The machine according to  claim 1 , wherein the sensor of the first automatic mechanism is an optical scale sensor. 
     
     
         3 . The machine according to  claim 1 , further comprising a movement mechanism for moving the grinding wheel from a first position offset with respect to the second rotation axis to a second position where a lateral face of the grinding wheel intersects the second rotation axis. 
     
     
         4 . A method for setting the tangency conditions between a grinding wheel and its environment in a grinding machine for bearing rings, the machine including:
 in addition to the grinding wheel which rotates around a first rotation axis;   a frame;   a working station where a bearing ring stands during a grinding operation of one of its surfaces;   a chuck for holding a bearing ring in the working station, this chuck being movable in rotation along a second rotation axis;   the method comprising steps of:   a) moving a shaping tool, to be used for shaping an outer peripheral edge of the grinding machine, in translation along a transverse axis, towards the first rotation axis by actuation of a first electric motor,   b) detecting a rotation of an output shaft of the electric motor via an encoder coupled to the electric motor,   c) detecting a position of the shaping tool along the transverse axis via a dedicated sensor,
 d) comparing a first output signal of the encoder with a second output signal of the dedicated sensor, 
   e) assessing that the shaping tool is tangent with the outer peripheral edge of the grinding wheel when the first output signal is representative of a rotation of the output shaft and the second output signal is representative of a stop of the shaping tool along the transverse axis,   f) moving the grinding wheel to a position where a lateral surface of the grinding wheel intersects the second rotation axis,   g) moving the grinding wheel in rotation around the first rotation axis,   h) moving the chuck in translation along the second rotation axis, towards the lateral surface of the grinding wheel, by actuation of a second electric motor,   i) detecting a rotation of a shaft integral in rotation with the chuck via a dedicated rotation sensor, and   j) assessing that the chuck is tangent with the lateral surface of the grinding wheel as soon as the dedicated rotation sensor detects a rotation of the shaft.   
     
     
         5 . The method according to  claim 4 , wherein when assessed in step e) that the shaping tool is tangent with the outer peripheral edge of the grinding wheel, the first electric motor is stopped. 
     
     
         6 . The method according to  claim 4 , wherein when assessed in step j) that the clutch is tangent with the lateral surface of the grinding wheel, the second electric motor is stopped. 
     
     
         7 . A method for shaping an outer peripheral edge of a grinding wheel of a grinding machine, the grinding machine comprising:
 a frame;   a rotating grinding wheel movable in rotation around a first rotation axis;   a working station where a bearing ring stands during a grinding operation of one of its surfaces;   a chuck for holding a bearing ring in the working station, this chuck being movable in rotation around a second rotation axis;   a first automatic mechanism to set a position of a shaping tool with respect to an outer peripheral edge of the grinding wheel, the first automatic mechanism includes an electric motor, an encoder coupled to the electric motor to detect a rotation of an output shaft of the motor, a sensor of the position of the shaping tool along a translation axis and a comparator to compare an output signal of the encoder and an output signal of the sensor, a second automatic mechanism to set the axial position of the chuck along the second rotation axis, these second automatic mechanism including an electric motor for driving the chuck in translation along the second rotation axis and a sensor to detect a rotation of the chuck around the second rotation axis;   the method comprising steps of:
 a) moving a shaping tool, to be used for shaping an outer peripheral edge of the grinding machine, in translation along a transverse axis, towards the first rotation axis by actuation of a first electric motor, 
 b) detecting a rotation of an output shaft of the electric motor via an encoder coupled to the electric motor, 
 c) detecting a position of the shaping tool along the transverse axis via a dedicated sensor, 
 d) comparing a first output signal of the encoder with a second output signal of the dedicated sensor, 
 e) assessing that the shaping tool is tangent with the outer peripheral edge of the grinding wheel when the first output signal is representative of a rotation of the output shaft and the second output signal is representative of a stop of the shaping tool along the transverse axis, 
 f) moving the grinding wheel to a position where a lateral surface of the grinding wheel intersects the second rotation axis, 
 g) moving the grinding wheel in rotation around the first rotation axis, 
 h) moving the chuck in translation along the second rotation axis, towards the lateral surface of the grinding wheel, by actuation of a second electric motor, 
 i) detecting a rotation of a shaft integral in rotation with the chuck via a dedicated rotation sensor, and 
 j) assessing that the chuck is tangent with the lateral surface of the grinding wheel as soon as the dedicated rotation sensor detects a rotation of the shaft. 
 k) moving the shaping tool in translation along the transverse axis, towards the first rotation axis, over a given stroke, wherein step k is implemented after at least one of:
 step e) when it is assessed that the shaping tool is tangent with the outer peripheral edge, and 
 step j) when it is assessed that the chuck is tangent with the lateral surface of the grinding wheel.