Reusable Push-In Fastener With Nested Pin And Deflectable Legs
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Solution Overview
Problem
Existing push-in fasteners face issues such as the pin not staying in a pre-drive position until the body is firmly seated, leading to improper seating and difficulty in disassembly, making them hard to reuse and potentially damaging when disassembled.
Innovation Solution
A push-in fastener design featuring a grommet with legs that remain in a relaxed state during pre-installation and rotate outwardly to increase diameter upon installation, with a pin that has distinct necks to secure the grommet in place, allowing for easy installation and secure retention, while being removable and reusable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the pin and body are completely separate before installation, then the fastener can be assembled in different configurations, but the pin cannot stay in a pre-drive position until the body is firmly seated
Solution Approach 1:
The pin is nested within the body in a pre-assembled unit, with the pin positioned in a recess of the body. This nesting arrangement allows the pin to be held securely in a pre-drive position relative to the body, preventing the pin from falling out while maintaining the ability to disassemble and reassemble the fastener.
2Reliability
If the drive interference between pin and body is increased to keep pin in pre-drive position, then pin position stability improves, but final connection becomes more difficult
Solution Approach 1:
The pin and body have different diameter sections with varying interference fits. The pin has a first diameter section that fits tightly in the body recess to maintain position, and a second diameter section that allows easier final connection. This local variation in dimensional quality enables both stable positioning and easy assembly.
3Reliability
If the fastener is designed to be securely retained, then reliability improves, but disassembly becomes difficult and may cause damage
Solution Approach 1:
The fastener uses deflectable legs that can dynamically change their state. During normal use, the legs are bowed outward to provide secure retention. During disassembly, the legs can be deflected inward to reduce retention force, allowing easy removal without damage. This dynamic behavior enables both strong retention and easy disassembly.
4Ease of operation
If the body and pin are preassembled, then handling and installation ease improves, but the pin may fall from the body or become locked improperly
Solution Approach 1:
The pin is preliminarily positioned in the body recess at a predetermined location before final installation. This preliminary action ensures the pin and body are correctly aligned and the pin cannot fall out during handling, while still allowing the fastener to be disassembled and reassembled properly.
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 design ensures the pin and grommet remain securely connected in a preassembled state for easy handling and installation, while allowing for easy disassembly and reassembly without damage, providing a secure and reusable fastening solution.
Implementation Method 1
a body inserted into an opening in an article. The body includes a collar larger than the opening in the article and deflectable portions or legs that yield as the body is inserted through the opening and rebound when fully through the opening.
Implementation Method 2
A pin of the fastener is inserted into and retained by the body after the body is seated in place in the articles. The pin wedges against the deflectable portions of the body to secure the body in place.
Data Source
AI summary
A re-usable push-in fastener includes a fastener grommet including a plurality of deflectable legs and a fastener pin which is inserted into the fastener grommet. The grommet and pin have a pre-installation relative position in which the pin is held in the grommet, with the legs of the grommet in relaxed positions. A full installation relative position for the grommet and pin includes the pin urging the legs outwardly against the surface of a hole in an object in which the grommet is installed.