Abstract: In order to improve the inner and outer surface contour accuracy of the bearing parts.Design a new semi rigid grinding tool spindle structure,through the analysis and modal test of main spindle system,study on the spindle system frequency and vibration type.The poor rigidity of the contact surface between the rigid abrasive tool and the main shaft is obtained,leading to the swing of the spindle end bending.That provides a theoretical basis and methods for semi-rigid poly urethane grinder spindle optimization design.Finally,using the device for dressing test,the surface roughnesses is better,and validate the feasibility and effectiveness of the proposed method.

Key words: semi rigid grinding spindle, dynamic analysis, dressing experiment, modal test analysis