The present invention relates to the bending of panels particularly panels to be used as skin for covering a cell within the structure of aircraft, rocket space vehicles or the like. The invention refers specifically to a device for bending panels of the type referred to above wherein the skin on one side carries stiffening ribs forming intersections or nodes and the device for obtaining bending and curving includes adjustable elements and deforming tool members which are operated under exertion of adequate force in order to obtain positive action under utilization of the location of adjacent nodes of the work and under consideration of changes in length wherein those ribs which run in the direction of curvature.
Panels of the types to which the invention pertains and particularly the bending of such panels requires working certain material which has a certain elasticity and plastic behaviour. A conventional material used here is aluminum. Parts are worked in this fashion particularly are required not only to have low weight but to provide low drag resistance as far as air flow is concerned which means that the panel outside has to be as smooth as possible and must not have any bumps, corners or the like, but there should be gradual and smooth transitions and curvature wherever needed, to be as streamlined as possible in order to avoid formation of drag resistance points for air-flow. In addition, such parts should be made in an economic fashion. Panels of the type to which the invention pertain may either be provided with integrated ribs etc. or ribs, strings or the like may have been added subsequently e.g. through rivetting or the like.
European patent No. 78 891 B1 suggests a method and equipment for bending panels particularly for covering cells in aerospace vehicles wherein deformation obtains through plastic straight line length changes of the ribs extending in the direction of curving and wherein the deforming forces in the ribs are provided at such a distance from the skin itself so that the tension in the panel results in a neutral line within the skin.
The present invention refers specifically to improvements in methods and practice as per this particular European patent and has as its specific task to improve equipment such that in between two adjacent nodes of the stiffening ribs the panel and transverse ribs be subjected to bending. These latter ribs are subject to length extension following the deforming. After the deformation process over entire extension has been completed, these ribs are provided with a constant or uniform stress distribution.