Patent ID: 8141855

Claim:
A stretch head, comprising: at least one clamp; a first body upon which the at least one clamp is mounted; a first drive mechanism mechanically coupled to the first body to move the first body in two opposing directions; a second drive mechanism mechanically coupled to the first drive mechanism so as to be moved in the two opposing directions by the first drive mechanism; a second body mechanically coupled to the second drive mechanism so as to be moved in the two opposing directions by the first drive mechanism and so as to be moved in two opposing directions by the second drive mechanism, the second body engaging the at least one clamp so as to transition the clamp to an unclamped state upon the second body being moved in one direction by the second drive mechanism and so as to transition the clamp to a clamped state upon the second body being moved in another direction opposite the one direction by the second drive mechanism, wherein the clamp comprises a first clamp finger providing a surface upon which a film to be stretched rests, a piston biased toward the surface of the first clamp finger by at least one spring, and a rocker that is mechanically coupled to the piston so as to apply a counter force to the piston to bias the piston away from the surface first clamp finger when the rocker is moved in a first direction and to reduce the counter force to allow the piston to abut the film and the surface of the first clamp finger when the rocker is moved in a second direction, and wherein the movement of the rocker occurs in relation to movement of the second body.