Dual Frame Gravity Bending for Glass Sheet Curvature Control
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Solution Overview
Problem
The existing gravity bending of glass sheets on a single frame often results in counter-bending defects, especially when shaping glass with complex orthogonal curvatures, and higher temperatures lead to optical distortions and enamel coverage issues, which are problematic for reducing the width of the enamel layer on vehicle windshields for aesthetic and visibility reasons.
Innovation Solution
A device with two sets of supports, where the longitudinal edges are initially supported by blank supports and then transition to finishing supports, while the side edges are continuously supported by finishing supports with the desired shape, allowing for precise control of bending and reducing the temperature required for bending, thus minimizing defects and enamel coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If bending is carried out on a single frame, then the device complexity is reduced, but counter-bending defects occur in the corners of the sheet
Solution Approach 1:
The bending process is segmented into multiple stages using different frames. The first frame performs initial bending, and the second frame performs finishing bending. This segmentation allows each frame to have optimized support characteristics for its specific stage, eliminating counter-bending defects while keeping individual frames relatively simple in structure.
Solution Approach 2:
The first frame performs preliminary bending to pre-shape the glass sheet before the second frame performs the final bending. This preliminary action prepares the glass for the subsequent finishing operation, allowing the second frame to achieve precise curvature without having to start from a completely flat state, thereby improving manufacturing precision.
2Productivity
If higher temperature is used for bending, then the bending speed increases, but optical distortions and peripheral marks increase
Solution Approach 1:
The first frame performs preliminary bending at lower temperature, achieving part of the required curvature before the glass is transferred to the second frame. This preliminary action reduces the remaining bending workload, allowing the second frame to complete the shaping at lower temperature and shorter time, thereby minimizing optical distortions and peripheral marks while maintaining overall productivity.
Solution Approach 2:
The bending process uses dynamic temperature control, adjusting the temperature profile according to the bending stage. The first frame operates at lower temperature for preliminary shaping, and the second frame operates at optimized temperature for final shaping. This dynamic approach balances bending speed and optical quality throughout the process.
3Manufacturing precision
If two successive supports are used for bending, then the manufacturing precision improves, but the bending time increases due to waiting time on the first support
Solution Approach 1:
The first frame performs preliminary bending quickly to prepare the glass for the second frame. By performing only the necessary preliminary shaping and not waiting for complete bending, the process minimizes waiting time on the first support while ensuring the glass is properly prepared for the second frame's finishing operation, thus reducing total bending cycle time.
4Shape
If the enamel layer is reduced in width for aesthetics, then the visibility improves, but the coverage of peripheral defects becomes insufficient
Solution Approach 1:
The first frame performs preliminary bending with support configuration optimized for that stage, and the second frame performs finishing bending with support configuration optimized for final quality. This two-stage approach with optimized preliminary action reduces peripheral defects to such an extent that a narrower enamel layer is sufficient to cover remaining imperfections, thereby allowing reduced enamel width while maintaining adequate defect coverage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the time and temperature required for bending, minimizing defects and allowing for a narrower enamel layer along the side edges of windshields, while maintaining the desired curvature, and enabling efficient bending of glass sheets with complex shapes.
Implementation Method 1
Gravity bending of sheets of glass on a gravity bending support
Data Source
Figure 1~3
Figure 4~6b
AI summary
The invention relates to a device for gravity bending a glass sheet, which includes a longitudinal grinder, including two longitudinal grinding mountings, and a finishing frame, including two lateral finishing mountings and two longitudinal finishing mountings. Said mountings form molding tracks. The distance between the centers of the longitudinal finishing mountings is shorter than the distance between the centers of the lateral finishing mountings. The grinder or the finishing frame is vertically movable relative to the other during bending, such as to pass from a rough bending configuration to a final bending configuration. Said device is characterized in that, in the rough bending configuration, the molding tracks of the longitudinal grinding mountings are higher than the molding tracks of the longitudinal finishing mountings. Said device is further characterized in that, in the final bending configuration, the molding tracks of the longitudinal finishing mountings are higher than the molding tracks of the longitudinal grinding mountings and in that the molding tracks of the lateral finishing mountings are the only molding tracks under the side edges of the glass in the rough bending configuration and in the final bending configuration. The invention also relates to the bending method using the device according to the invention. The invention particularly makes it possible to produce a glass panel having an enamel layer that is less wide on the side edges than on the longitudinal edges.