Hemmed Edge Garage Door Section Weight Reduction
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Solution Overview
Problem
Existing overhead garage door sections are heavier and more expensive than necessary, particularly for single-car garage doors, due to the thickness of sheet steel required for strength and stiffness.
Innovation Solution
A hemmed edge overhead garage door section configuration with thicker top and bottom rails and a thinner face, formed integrally from a single material, eliminating the need for rearwardly extending struts and reducing overall weight and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional uniform thickness sheet steel is used for door sections, then sufficient strength and stiffness are achieved, but weight and cost increase significantly
Solution Approach 1:
The door section employs non-uniform thickness distribution: the face is made thinner (24-gauge or less) to reduce weight, while the rails are made thicker (20-gauge or more) through hemming to provide localized strength and stiffness where structurally necessary. This resolves the contradiction by concentrating material only where needed for structural performance.
Solution Approach 2:
The invention transitions from a two-dimensional uniform thickness approach to a three-dimensional variable thickness structure by hemming the edges of the sheet metal to create thicker rails. This adds a dimensional aspect to thickness control, allowing the door section to achieve required strength with less overall material and reduced weight.
2Strength
If thicker sheet steel is used throughout the door section, then strength and stiffness requirements are met, but manufacturing cost increases
Solution Approach 1:
Instead of using expensive thick material throughout the entire door section, the invention applies thick material (via hemming) only to the rails where structural strength is critical, while keeping the face material thin and inexpensive. This localized approach reduces overall material cost while meeting strength requirements.
Solution Approach 2:
The door section is segmented into distinct functional zones: the face (non-structural, thin material) and the rails (structural, thick material via hemming). This segmentation allows differential material specification, reducing total material cost compared to using thick material uniformly across the entire section.
3Ease of manufacture
If uniform thickness sheet steel is used, then manufacturing process is simple, but weight and material usage increase
Solution Approach 1:
The hemming operation is performed during the initial roll-forming process while the sheet metal is being shaped into the door section profile. This preliminary action of hemming the edges integrates the thickness variation into the base manufacturing process without requiring separate operations, maintaining manufacturing simplicity while achieving weight reduction.
Solution Approach 2:
The invention merges two functions into one manufacturing step: the roll-forming process simultaneously creates both the door section profile and the hemmed thicker rails. This consolidation maintains ease of manufacture while enabling the variable thickness design that reduces weight.
Data Source
AI summary
A hemmed edge overhead garage door section having a face, a top rail integral with the face formed longitudinally therealong, the top rail having at least a top rail body extending rearwardly from the face and a top rail leg extending downwardly from the top rail body offset from the face, the top rail body and at least a portion of the top rail leg being thicker than the face, and a bottom rail integral with the face formed longitudinally therealong opposite of the top rail, the bottom rail comprising at least a bottom rail body extending rearwardly from the face and a bottom rail leg extending upwardly from the bottom rail body offset from the face, the bottom rail body and at least a portion of the bottom rail leg being thicker than the face.