Integrally Formed Wedge End Stops for Reclosable Fastener Slider Containment
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Solution Overview
Problem
Conventional reclosable fasteners for thermoplastic bags lack sufficient seal strength and flexibility, and often require additional components or processing steps, such as end termination clips or ultrasonic shaping, which increase costs and complexity.
Innovation Solution
A reclosable fastener assembly featuring interlocking plastic tracks with integrally formed wedge-shaped end stops that prevent the slider from moving beyond the ends, reducing material usage and allowing for easier opening and closing, and formed through methods like ultrasonic welding or injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional end termination clips are used to prevent slider from going past ends, then slider containment is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The end stop structure is merged with the fastener tracks themselves, forming an integral part of the fastener assembly. The tracks are shaped to protrude beyond the slider's path, eliminating the need for separate end termination clips while maintaining slider containment functionality
Solution Approach 2:
The end stop function is extracted from the track material itself through shaping or forming processes, creating protruding portions that serve as built-in end stops without requiring additional components
2Ease of manufacture
If ultrasonic shaping is used to form end stops, then end stop structures are created, but manufacturing time and energy increase
Solution Approach 1:
The end stop structures are formed during the initial track formation process through injection molding or extrusion, rather than requiring subsequent ultrasonic shaping operations. This preliminary formation eliminates additional processing steps and reduces manufacturing time
Solution Approach 2:
The mechanical ultrasonic shaping process is replaced with a molding process that forms the end stop structures directly during track fabrication, substituting a more efficient forming method that reduces processing time and energy consumption
3Strength
If conventional fastener profiles are used, then manufacturing simplicity is maintained, but seal strength and flexibility are insufficient
Solution Approach 1:
The track profile incorporates localized variations in geometry, with specific regions having enhanced thickness or reinforcement to improve seal strength where needed, while other regions maintain simpler geometries to preserve manufacturing efficiency
Solution Approach 2:
The fastener assembly uses composite construction with tracks and end stops formed from thermoplastic materials that provide both structural integrity and sealing capability, combining multiple material properties in a single integrated component
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 enhances seal strength and flexibility while reducing material usage and eliminating the need for additional components, improving manufacturing efficiency and cost-effectiveness.
Implementation Method 1
U.S. Pat. Nos. 7,267,856 and 7,669,307, each of which is incorporated by reference in its entirety, describe one technique to shape end stop structures by ultrasonically smashing the opposite ends of the male and female profiles of the fastener to form the protruding end stop structures.
Implementation Method 2
formed through methods like ultrasonic welding or injection molding
Data Source
AI summary
Reclosable fastener assembly includes a fastener comprising a pair of interlocking tracks including a first track having a male profile and a second track having a female profile, the fastener having a height and a width when the tracks are interlocked, a slider slidably mounted to the tracks for movement between a closed position and an open position, and at least one end stop located at an end of the fastener, the end stop formed integrally from at least one of the first and second tracks, the end stop having a wedge shape with a first end, a second end, and a lateral extent, the first end being proximate the fastener and having a height no greater than the height of the fastener, the end stop having a decreasing height from the first end to the second end, and the lateral extent extending beyond the width of the fastener.