Inventors:
Martin De Vries - Holland MI
Donald L. Bareman - Holland MI
Mervin Dirkse - Holland MI
Niels Alfred Olesen - Zeeland MI
James M. Beebe - Grand Haven MI
Assignee:
Donnelly Corporation - Holland MI
International Classification:
C03B 2303
B28B 732
B21D 3100
Abstract:
A method of and apparatus for bending a sheet of material heated to a formable, state such as glass, resinous polymeric material, viscoelastic material, and thermoplastic material, provides an improved pressing member for pressing the heated sheet against a first rigid mold which reduces the size of the buckles in the bent sheet, eliminates the need for a second rigid mold, reduces the process control steps, reduces the risk of damaging the rigid mold, increases the tolerances for the positioning of the sheet in the apparatus, and increases the range of application. The pressing member includes a flexible diaphragm which rolls the heated sheet against a rigid mold by first applying a pressure to a portion of the heated sheet and then radiating the pressure from that portion to the remaining surface area of the heated sheet in a rolling action. The bending apparatus includes a rigid mold and a flexible diaphragm pressurized into a convex shape for initially pressing on a portion of the heated sheet. A control system moves the pressing member toward the rigid mold and maintains the pressure on the flexible diaphragm so that as the pressing member is moved toward the rigid mold, the flexible member generally conforms to the shape of the rigid mold and rolls the heated sheet onto the rigid mold.