Moving follower rest design using vibration absorbers for ball screw grinding

A novel design of follower rest used in ball screw grinding machine is proposed. Installed on the grinding wheel holder and moving along the ball screw, the follower rest is designed to be a vibration absorber with its driving point attached on the ball screw close to the grinding zone. It is used not only to suppress the ball screw vibration at the position close to the grinding zone but also to avoid the occurrence of chatter. It provides an auxiliary in counteracting the ball screw vibration during a grinding process besides the traditional steady rest fixed on the machine bed. The mechanisms in ball screw vibration reduction as well as in avoiding the chatter using the absorber are formulated and studied using the impedance method. Influences of design parameters of the absorber, i.e. the absorber mass and the absorber damping, on the chatter and the transient response of the ball screw are examined in detail. Results show that increasing the mass of the absorber is the most effective way with respect to vibration reduction at the grinding position as well as avoiding the chatter. On the other hand, the absorber damping has a negative effect both on the vibration reduction of ball screw and avoiding the chatter because it reduces the driving point impedance of absorber at resonance, which is contrary to the structural damping of the ball screw that has a positive effect in avoiding the chatter. Moreover the absorber damping has little influence on the frequency bandwidth in which the ball screw vibration is suppressed by the absorber.