Film stretcher

Abstract

A film stretcher utilizes a spring bias to clamp the film. The film stretcher may include a stretch head having one or more clamps positioned about the film in locations necessary to clamp the film for stretching in one or more axes. The clamp may utilize a spring to provide the clamping force. The stretch head may include structures that operate to counter the spring bias to move the clamp to one state and then to allow the spring bias to move the clamp to another state. Thus, the stretch head may effectively clamp and unclamp the film.

1 . A clamp for clamping film within a film stretcher, the clamp comprising:
 a first clamp finger providing a surface to abut the film;   at least one spring having a position fixed in relation to the first clamp finger;   a piston receiving a bias from the at least one spring so as to produce a clamping force against the surface of the first clamp finger; and   a rocker mechanically linked to the piston, the rocker providing a bias to the piston opposite the bias of the at least one spring when moved in a first direction and the rocker releasing the bias to the piston that is opposite the bias of the at least one spring when moved in a second direction.   
     
     
         2 . The clamp of  claim 1 , further comprising a second clamp finger fixed relative to the first clamp finger, and wherein the at least one spring is mounted to the second clamp finger. 
     
     
         3 . The clamp of  claim 1 , further comprising a slider that slides relative to the first clamp finger and engages the rocket to move the rocker the first direction and the second direction. 
     
     
         4 . The clamp of  claim 3 , wherein the slider includes a detent and wherein the rocker includes a roller that engages a surface of the slider and that seats into the detent to hold the rocker in a fixed position where the rocker biases the piston against the bias of the at last one spring. 
     
     
         5 . The clamp of  claim 1 , wherein the at least one spring comprises at least one leaf spring. 
     
     
         6 . The clamp of  claim 1 , wherein the at least one spring comprises a coil spring. 
     
     
         7 . The clamp of  claim 1 , wherein the at least one spring comprises a disc spring. 
     
     
         8 - 20 . (canceled)