Press Forming Glass Sheets with Segmented Lower Ring
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Solution Overview
Problem
Existing glass sheet press forming technologies face challenges in efficiently forming glass sheets with transverse curvature, particularly in maintaining straight line elements without significant curvature during the forming process, which affects the quality and optical clarity of vehicle windshields.
Innovation Solution
A press station system that includes a lower ring with end and intermediate portions movable vertically, and an upper mold with a downwardly facing convex surface, where the glass sheet is initially formed with upwardly concave shapes and then progressively curved by the ring and mold to achieve transverse curvature, allowing for independent movement of the ring portions to form the glass sheet's straight line elements with precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the glass sheet is formed with transverse curvature using conventional press forming, then the glass sheet achieves the desired curved shape, but the straight line elements develop significant curvature causing distortion and reduced optical clarity
Solution Approach 1:
The lower ring is divided into end portions and intermediate portions that can move vertically independently. This segmentation allows differential movement where end portions are raised first to form straight line elements with curvature while intermediate portions remain stationary, preventing unwanted curvature in regions where straight line elements should be maintained
Solution Approach 2:
The end portions of the lower ring are moved upwardly before the intermediate portions to preliminarily form the straight line elements at the ends of the glass sheet. This preliminary action ensures that curvature is introduced only where needed while preserving straight line elements in intermediate regions during the forming process
2Ease of manufacture
If the entire lower ring is moved upwardly to form the glass sheet, then the forming process is simplified, but it becomes difficult to maintain straight line elements without significant curvature
Solution Approach 1:
The lower ring is segmented into independently movable end portions and intermediate portions, allowing complex differential movement patterns that would be difficult to achieve with a monolithic ring. This segmentation maintains ease of manufacture by using a single ring structure while enabling precise control over which regions of the glass sheet receive curvature
Solution Approach 2:
The lower ring transitions from a static structure to a dynamic one where different segments can move at different times and by different amounts. This dynamic capability allows the system to adapt during the forming process, raising end portions first to create curvature where needed while keeping intermediate portions stationary to maintain straight line elements
3Shape
If glass sheets are formed with transverse curvature, then the desired shape is achieved, but excess glass accumulates at the periphery affecting quality
Solution Approach 1:
The lower ring applies different movements to different regions: end portions are raised to create transverse curvature and reduce peripheral glass excess at the edges, while intermediate portions remain stationary to maintain straight line elements and prevent unwanted curvature. This local differentiation optimizes the forming process by addressing peripheral excess only where necessary
Data Source
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AI summary
A method, press station (12), and system (10) for forming glass sheets that are initially formed with an upwardly concave curved shape with end portions (86) and an intermediate portion (88) having straight line elements that are subsequently formed with curved shapes to provide curvature along transverse directions. The forming is performed by initially providing curvature to the straight line elements of the glass sheet end portions while the intermediate portion (88) still has the straight line elements. The glass sheet intermediate portion is subsequently formed to provide curvature to its straight line elements so the glass sheet has curvature in transverse directions.