Method and apparatus for bending thin glass
The present invention provides for a method and apparatus for bending multiple sheet of thin glass at the same time on a single set of molds. Multiple sheets of thin glass are stacked onto a full surface female mold. A partial surface male mold is placed onto the thin glass stack. The male mold serves to hold the edges in place and prevents the formation of wrinkles as the glass is heated and sags to conform to the shape of the female mold. Optionally, the top mold can be enclosed and pressurized to provide a pneumatic pressure assist to form the glass. In addition, the bottom mold can be enclosed to allow for vacuum assist to form the glass.
1. A method for bending automotive thin glass sheets, comprising:
providing a full surface bottom concave mold and a partial surface top mold;
stacking at least one thin glass sheet onto the full surface bottom concave mold such that the periphery area of said at least one thin glass sheet is in contact with the bottom concave mold;
applying the partial surface top mold to said at least one thin glass sheet, said partial surface top mold contacting the periphery area of said at least one thin glass sheet; and
heating said at least one thin glass sheet to its glass transition point such that the at least one thin glass sheet sags under the force of gravity, adopting the shape of the full surface bottom concave mold.
2. The method of claim 1 , wherein the thickness of said at least one thin glass sheet is of less than 1.8 mm.
3. The method of claim 1 , further comprising applying a clamping force to the at least one thin glass sheet to force said at least one thin glass sheet to conform to the full surface bottom concave mold.
4. The method of claim 1 , further comprising aligning said at least one thin glass sheet and molds.
5. The method of claim 1 , wherein the step of providing a full surface bottom concave mold comprises: bending a sheet of glass having a glass transition point that is sufficiently higher than that of said at least one thin glass sheet and having a thickness sufficient for said mold to retain its shape during bending of said at least one thin glass sheet.
6. The method of claim 1 , wherein the step of providing a partial surface top mold comprises: providing a partial surface top mold having a ring type structure.
7. The method of claim 1 , further comprising applying pneumatic pressure to said partial surface top mold constructed such as to enclose a volume of air and serve as a plenum.
8. The method of claim 1 , further comprising applying vacuum to said full surface bottom concave mold constructed such as to enclose a volume of air and serve as a plenum to allow evacuation of air between full surface bottom concave mold and said at least one thin glass sheet.
9. The method of claim 1 , further comprising adding additional weight to the partial surface top mold.
10. The method of claim 1 , further comprising covering the edge of the partial surface top mold that comes in contact with the at least one thin glass sheet with a layer of glass cloth to prevent marking of said at least one thin glass sheet.