Patent ID: 6290574
Filing Date: 2001-09-18
Classification: B23F,B24B

Abstract:
A method of centering a dressing tool in a thread of a grinding worm, a thread having opposed first and second flanks, a cylindrical outer surface and a root, the grinding worm being connected to a rotary encoder to measure a rotating angel of the grinding worm, the method comprising the steps of:precentering the dressing tool relative to the thread comprising the steps of:rotating the grinding worm,rotating the dressing tool without axial feed motion of the dressing tool,infeeding the dressing tool radially relative to the grinding worm until a circumference of the dressing tool comes into contact with the cylindrical surface,sensing noise adjacent to an outside diameter of the grinding worm and the dressing tool by an acoustic sensor,detecting if a signal of the acoustic sensor is above or below a preselected fist value in relation to the rotating angle of the grinding worm and storing that information,determining a middle position between the first and second tooth flanks from the relationship between the sensor signal and the rotating angle of the grinding worm,the precentering steps being succeeded by precision centering steps comprising the steps of:feeding the rotating dressing tool into the thread of the rotating grinding worm in the middle position between the first and second tooth flanks to a radial position between a diameter of the cylindrical surface and a diameter of the root and moving the dressing tool in an axial direction of the grinding worm synchronously with the rotating grinding worm to follow the thread,superimposing on the synchronous axial movement of the dressing tool an additional axial movement in both senses until the dressing tool comes into contact with the first and second flanks,sensing a moment of contact between the dressing tool and the respective flank by the sensor and stopping the additional axial movement when the sensor signal exceeds a second preselected value,calculating an accurate center of the thread from measurements achieved of the relative additional axial movement of the dressing tool in the two senses.