Abstract: An active piezoelectric spindle bearing preload adjustment mechanism includes a preload adjustment assembly located between an inner ring and an outer ring of two bearings, and an internal generator mounted at a selected location in a spindle. The preload adjustment assembly includes a spacer ring set and a piezoelectric actuator located in the spacer ring set. The rotation speed of the spindle is changeable to enable the internal generator generating selected amount of power and voltage for controlling extension or contraction length of the piezoelectric actuator whereby to change slide distance between the inner and outer ring for controlling bearing preload value.

Abstract: An active piezoelectric spindle bearing preload adjustment mechanism includes a preload adjustment assembly located between an inner ring and an outer ring of two bearings, and an internal generator mounted at a selected location in a spindle. The preload adjustment assembly includes a spacer ring set and a piezoelectric actuator located in the spacer ring set. The rotation speed of the spindle is changeable to enable the internal generator generating selected amount of power and voltage for controlling extension or contraction length of the piezoelectric actuator whereby to change slide distance between the inner and outer ring for controlling bearing preload value.

Abstract: An automatic pallet changer is composed of a pallet lifting mechanism and a revolving mechanism. The pallet lifting mechanism has a pallet platform and a lifting rod which is fastened with the bottom of the pallet platform. The pallet platform and the lifting rod are driven by oil pressure to move up and down in a linear manner. The body of the lifting rod is provided with a vertically-oriented first position confining portion. The revolving mechanism has a gear and a rack gear member. The gear is pivoted to the bottom of the pallet lifting mechanism at a fixed height and provided axially with a slide channel in which the lifting rod is slidably disposed. The slide channel is provided in the inside thereof with a vertically-oriented second position confining portion, which is complementary in shape to the first position confining portion of the lifting rod for enabling the lifting rod and the pallet platform to turn synchronously.