Tool chuck for use with a rotating machine

A tool chuck for use with a rotating machine, comprising:

• a central component having an axis and comprising a rear part designed to be fixed to a drive shaft of the rotating machine and a front part to which are connected a number of jaws each having a central longitudinal plane;
• and
• means for moving the jaws between a tool clamping position and a release position;
• which chuck comprises
• a seat formed on the inward side of each jaw, said seat comprising an opening turned towards the axis of the central component, a back behind the opening, and, approximately parallel to the axis of the central component, first and second lateral faces;
• and
• at least one roller mounted in and approximately against the back of each seat with the aid of a rigid retaining member separated from the retaining member of each of the other jaws, the roller being rotatable about its axis which is approximately parallel to the axis of the central component, and movable translationally between the two lateral faces of the seat, the distance between which faces is greater than the diameter of the roller, and the roller being capable of acting on the jaw and on the tool;
• the back of which seat has two bearing portions, a first and a second, extending from the first lateral face and second lateral face, respectively, to the central longitudinal plane of the jaw, each bearing portion being curved or inclined transversely in such a way that the distance between the axis of the central component and said bearing portion increases with proximity to the central longitudinal plane, said bearing portions being adjacent and symmetrical about the central longitudinal plane and, where they meet, forming a roller positioning cavity so that when the tool is placed between the jaws the roller positions itself in contact with the back of the seat, essentially in the positioning cavity.