Automotive Glass Plate Edge Compression and Inner Tension Control
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Solution Overview
Problem
Conventional laminated glass sheets for automobiles in flush-mount structures face challenges with edge compression (E/C) and inner tension (I/T) levels, leading to potential breakage from external factors like flying stones, and existing methods are limited in producing glass sheets with suitable stress distributions for both edge strength and reduced I/T.
Innovation Solution
A glass sheet with a peripheral region of edge compression (10-18 MPa) and an intermediate region of inner tension (up to 2.4 MPa) is developed, along with a production process involving heating, bending, and annealing, where the glass sheet is cooled to below the strain point before lifting, creating a temperature gradient to manage stress distribution effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional glass sheets are used with large E/C to ensure edge strength, then edge strength is improved, but I/T increases leading to peripheral portion fragility
Solution Approach 1:
The patent applies local quality by creating distinct stress distribution zones: a peripheral region (0-50mm from edge) with controlled E/C of 10-18 MPa, an intermediate region (50-150mm from edge) with minimal I/T of 0-2.4 MPa, and a central region with higher stress tolerance. This localized stress control ensures edge strength where needed while protecting the peripheral portion from fragmentation.
2Weight of moving object
If thin glass sheets (1.5-3.2mm) are used to reduce weight, then weight is reduced, but the glass becomes more susceptible to breakage without sufficient E/C and I/T control
Solution Approach 1:
The patent applies parameter changes by precisely controlling stress distribution parameters in thin glass sheets (1.5-3.2mm thickness). By setting E/C in the peripheral region to 10-18 MPa and I/T in the intermediate region to 0-2.4 MPa, the invention optimizes the strength parameters of thin glass to prevent breakage during flush-mount installation while maintaining weight reduction benefits.
3Ease of manufacture
If glass sheets with large I/T are used, then manufacturing is simpler, but the glass tends to fragment when exposed to external factors like flying stones
Solution Approach 1:
The patent applies preliminary action by pre-forming the desired stress distribution (E/C in peripheral region, minimal I/T in intermediate region) during the glass manufacturing process before the glass is installed. This preliminary stress conditioning ensures that when the glass is later exposed to external impacts like flying stones, the peripheral portion is already protected from fragmentation due to the controlled stress state.
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
The solution provides a glass sheet with enhanced edge strength and reduced I/T, suitable for flush-mount structures, effectively preventing breakage and ensuring high edge strength and low I/T, thus improving the durability of laminated glass in automotive applications.
Implementation Method 1
the forming mold is conveyed into a heating furnace, thereby to heat the glass sheet into the vicinity of the glass-softening point in the heating furnace. In this forming method, since the glass sheet is softened to be bent along the bending-forming surface of the forming mold by gravity
Implementation Method 2
the glass sheet is cooled to below the strain point before lifting, creating a temperature gradient to manage stress distribution effectively
Implementation Method 3
a production process involving heating, bending, and annealing, where the glass sheet is cooled to below the strain point before lifting
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3~4
AI summary
A glass sheet for a laminated glass to be fit into a frame of an automobile in a flash-mount structure, that is a glass sheet having a good strength, is provided. In the glass sheet of the present invention, the maximum value of the plane compressive stress on the edge of the glass sheet is at least 10 MPa and at most 18 MPa, and the maximum value of the plane compressive stress inside from the edge of the glass sheet is at most 2.4 MPa.