Method for three stage forming a hot glass sheet with transverse curvature

A three stage method for forming a hot glass sheet with transverse curvature comprising:

• initially forming the glass sheet against a downwardly facing first upper mold that has curvature in a first direction and straight line elements in a second direction transverse to the first direction;
• then transferring the glass sheet from the first upper mold onto an upwardly facing lower mold having curvature in the first direction and permitting the glass sheet to sag under gravity to have some curvature in the second direction as well as curvature in the first direction;
• thereafter press forming the glass sheet between the lower mold and a downwardly facing second upper mold that has transverse curvature and is complementary to the lower mold so the glass sheet has transverse curvature corresponding to the shapes of the lower mold and the second upper mold;
• and the method further being performed by:
• conveying the hot glass sheet on a roll conveyor into a heated chamber of a forming station to below the first upper mold at a pickup position thereof within the heated chamber above the conveyor, with the first upper mold having a downwardly facing surface of a convex shape with curvature in the first direction and straight line elements in the second direction transverse to the first direction, with the first upper mold in the pickup position being spaced horizontally from the lower mold, which faces upwardly, and from the second upper mold which is located above the lower mold, and with the second upper mold located within the heated chamber above the elevation of the conveyor and having a downwardly facing surface of a convex shape with its transverse curvature;
• supporting the first upper mold on elongated beams that are supported by rollers for horizontal movement within the heated chamber under the operation of a horizontal actuator for horizontal movement of the first upper mold between the pickup position above the roll conveyor and a delivery position below the second upper mold and above the lower mold, and supporting the rollers on vertical actuators that move the rollers and the elongated beams and the first upper mold supported thereon vertically;
• moving the first upper mold at its pickup position downwardly from an upper position to a lower position adjacent the glass sheet on the roll conveyor and supplying upwardly directed gas lift jets to lift the glass sheet from the conveyor and provide the initial forming of the glass sheet against the downwardly facing surface of the first upper mold, the first upper mold then being moved upwardly to its upper position with the glass sheet supported by the first upper mold, and a vacuum being drawn by a vacuum source at the first upper mold to support the glass sheet thereon;
• then moving the first upper mold at its upper portion and the glass sheet supported thereon by the vacuum horizontally within the heated chamber from the pickup position to the delivery position below the second upper mold and above the lower mold which has an upwardly concave shape complementary to the convex shape of the downwardly facing surface of the second upper mold;
• subsequently terminating the vacuum drawn at the first upper mold in the delivery position to transfer the glass sheet onto the lower mold, moving the first upper mold back to the pickup position, moving the second upper mold from an upper position downwardly to cooperate with the lower mold in the press forming of the glass sheet, and then moving the second upper mold upwardly to its upper position with the press formed glass sheet supported on the second upper mold by vacuum drawn by the vacuum source at its downwardly facing surface;
• then moving a delivery mold to below the press formed glass sheet on the second upper mold in its upper position whereupon the vacuum is terminated to release the glass sheet from the second upper mold onto the delivery mold which is then moved out of the forming station for delivery of the press formed glass sheet;
• and
• operating a controller to control the roll conveyor, the horizontal actuator and the vertical actuators as well as the first upper mold moved that is thereby, the vacuum source, and the delivery mold to perform the press forming of the glass sheet and its delivery.