Apparatus and method for making paraboloidal surfaces

Apparatus for dishing a circular flat sheet of deformable material comprising:

• (a) a base frame;
• (b) a circular sheet-receiving table supported by the base frame;
• (c) a plurality of clamping means supported by the base frame and spaced equally about the periphery of the table, the clamping means each having a clamping surface, each said clamping surface of each clamping means when in clamping position being oriented to direct clamping force downwardly towards the table surface;
• (d) a rigid annular clamping ring having an upper surface to receive each of the clamping surfaces of the clamping means when in clamping position and a lower, clamping surface to bear against the upper surface of the sheet when in position on the table to evenly distribute the clamping forces from the clamping means about the lower clamping surface;
• (e) an upstanding swaging means supported on the surface of the table to uniformly engage and upwardly turn the edge of the sheet when under clamping pressure from the clamping ring;
• (f) fluid supply means communicating with the surface of the table to supply fluid between the sheet and table surface for deforming and thereby shaping the sheet;
• (g) control means associated with the fluid supply means for providing appropriate fluid for deforming and shaping the sheet;
• and
• (h) gasket means on the table surface to extend between the table surface and the sheet to prevent fluid leaking during deformation of the sheet when the clamping means are in clamping position,
• the clamping means to provide sufficient force on the clamping ring to hold the sheet in position, upwardly turn the edge of the sheet against the upstanding swaging means, prevent escape of fluid from between the sheet and table surface during the deforming operation and prevent inward slippage of the sheet.