A stretch-forming machine of the type wherein a pair of opposed curving jaw assemblies grip opposite end edge portions of a metal sheet for initially stretching the metal sheet into a yield state and forming the metal sheet into a predetermined curved configuration. Each jaw assembly includes a jaw having an array of adjacent grippers or groups of grippers moveable relative to each other to define a part of the curve of the jaw and adapted to extend along one side edge of the metal sheet from adjacent a first corner to adjacent a second corner of the sheet, a moveable yoke connected to the jaw, a pivot connecting the yoke to a beam way, and at least one actuator connected to the yoke for pivoting the jaw about the pivot to urge the grippers at opposing ends of the gripper array away from the pivot while the grippers adjacent a centerline of the gripper array remain approximately stationary. The pivot and the actuator cooperate to stretch the outer corners of the metal sheet while substantially minimizing elongation along the centerline of the metal sheet.