Patent ID: 7055346

Claim:
A circular knitting machine for hosiery, with a device for actuating the knockover sinkers, comprising: a needle cylinder, arranged with an axis thereof substantially vertical, said needle cylinder being actuatable so as to rotate about said axis; a sinker ring, rigidly coupled to said needle cylinder in rotation about said axis and arranged coaxially to the needle cylinder proximate to an upper end thereof, said sinker ring being provided with a plurality of knockover sinkers supported thereat, which are radially movable with respect to the needle cylinder and the sinker ring; a sinker cover composed of an upper ring and a lower ring and arranged in an upward region and coaxially with respect to said sinker ring with supporting thereat at least one cam and at least one complementary can, which is arranged outside said at least one cam with respect to the axis of the needle cylinder; said at least one cam and said complementary cam forming portions of a path that runs round the axis of the needle cylinder and is engageable by a heel of the knockover sinkers in order to actuate movement of the knockover sinkers along a radial direction with respect to the needle cylinder when the needle cylinder rotates about said axis with respect to said sinker cover, said at least one cam and said complementary cam, said complementary cam being movable with respect to said sinker cover along a direction that is substantially radial to the axis of the needle cylinder; first actuation means, acting on said sinker cover to turn the sinker cover about said axis of the needle cylinder; second actuation means, adapted to vary a movement extent of said complementary cam along said substantially radial direction with respect to said axis of the needle cylinder; wherein said first actuation means comprises a first electric motor which is supported by a fixed structure and is provided with an output shaft to which a first actuation cam is keyed, said actuation cam being coupled to a pair of cam followers, which are connected to said upper ring of the sinker cover and are arranged so as to provide a bilateral and preloadable coupling with a profile of said first actuation cam.