Roller Shade Hem Bar Assembly With Wedge Retention
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Solution Overview
Problem
Existing roller shade hem bar attachment methods, which often require welding, can damage the shade material, cause puckering, and limit the use of certain fabric types, and are complicated for textured fabrics, especially when trying to insert a metal rod or spline through a pocketed construction.
Innovation Solution
A hem bar assembly with longitudinal hem bar portions featuring channels and tubular splines that wedge and retain the shade material, along with a retaining clip system using hooked arms and alignment projections to secure the hem bar portions together without welding, allowing for different styles and accommodating various fabric widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to attach the shade material to the hem bar, then the attachment strength is improved, but the shade material may appear wavy or puckered, or shrink
Solution Approach 1:
The patent introduces a longitudinal spline as an intermediary component between the shade material and hem bar. The spline receives the shade material through a pocket construction and transmits it through the hem bar without direct welding contact, thereby maintaining attachment strength while preventing thermal damage and distortion to the fabric
Solution Approach 2:
The patent replaces the welding process (thermal/mechanical system) with a mechanical insertion system using a longitudinal spline and pocket construction. This substitution eliminates heat-related damage while maintaining secure attachment through mechanical friction and geometric constraints
2Strength
If welding is used to attach the shade material to the hem bar, then the attachment strength is improved, but it does not work for shade material that do not weld well, resulting in the appearance of puckering
Solution Approach 1:
The patent creates a universal attachment system using the longitudinal spline and pocket construction that works with all fabric types regardless of weldability. The mechanical insertion method through the spline channel provides consistent attachment strength across diverse materials including multi-ply and delaminate fabrics that cannot be welded
3Object-affected harmful factors
If the folded end of the shade material is inserted through the longitudinal opening in the hem bar to form a pocket, then welding is avoided, but the process is complicated and may cause the shade material to pucker
Solution Approach 1:
The longitudinal spline acts as a mediator that simplifies the pocket formation process. Instead of directly inserting folded fabric through a long channel (which causes puckering), the spline provides a guided pathway with tapered surfaces that gradually receive and smooth the fabric, reducing complexity and preventing damage
Solution Approach 2:
The patent incorporates preliminary action by providing alignment projections and tapered surfaces on the spline that guide the shade material into proper position before full insertion. This pre-alignment prevents misalignment and puckering during the insertion process, making the overall process simpler and more reliable
4Object-affected harmful factors
If a metal rod or spline is inserted through the shade material pocket, then welding is avoided, but textured fabrics may catch on the rod or spline causing pucker and damage
Solution Approach 1:
The patent applies curvature by providing a rounded or tapered leading edge on the longitudinal spline. This curved surface smoothly guides the spline into the fabric pocket without sharp edges that would catch on textured fabrics, thereby preventing pucker and damage while maintaining ease of insertion
Solution Approach 2:
The longitudinal spline with its specially designed surface characteristics acts as an intermediary that is compatible with textured fabrics. The spline's surface properties mediate between the insertion requirement and the fabric's texture, allowing smooth passage without direct harmful contact between the insertion tool and fabric surface
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 solution simplifies the attachment process, prevents damage to the shade material, enables the use of a broader range of fabric types, and allows for easy customization and replacement of hem bars, while avoiding the issues of puckering and material shrinkage associated with welding.
Implementation Method 1
at least one tubular spline adapted to wedge and retain the shade material within one of the first channel and the second channel
Implementation Method 2
at least one tubular spline adapted to wedge and retain the shade material within one of the first channel and the second channel
Data Source
AI summary
A hem bar assembly that secures to a shade material of a roller shade comprising first and second hem bar portions each including an inner face having a first channel, a second channel, and third channel located between the first and second channels. The hem bar assembly further comprises at least one tubular spline that wedges and retains the shade material within one of the first channel and the second channel of one of the first and second hem bar portions. The hem bar assembly further comprises a longitudinal retaining clip having at least a pair of oppositely disposed hooked arms outwardly extending therefrom, wherein each hooked arm is adapted to enter and clip to one of the third channels in a respective first and second hem bar portions to attach the first hem bar portion to the second hem bar portion.